REVIEW | doi:10.20944/preprints201907.0286.v1
Subject: Life Sciences, Virology Keywords: HIV-1 Gag; Gag inhibitors; Protease; Protease inhibitors; drug resistance mutations; drug design
Online: 25 July 2019 (10:05:03 CEST)
HIV treatment strategies against viral enzymes are continuously hampered by viral drug resistance. Recent findings show that viral substrate Gag contributes to HIV-1 Protease Inhibitor (PI) resistance, leading to demands for new strategies in HIV treatment where Gag is recognized as a drug target. To successfully target Gag, there is a need of in-depth understanding of the Gag polyprotein and the effects of Gag mutations. Here, we propose new strategies in designing novel Gag inhibitors against existing and novel emerging Gag mutations via a structural understanding of the Gag-Protease relationship in PI resistance. In this review, we discuss the role of both novel and previously reported mutations, revealing insights to how they aid in PI resistance, and how new Gag inhibitors can be designed.
REVIEW | doi:10.20944/preprints202002.0099.v1
Subject: Life Sciences, Virology Keywords: retroviruses; HIV-1; reverse transcriptase; mutation rate; drug resistance, allostery
Online: 7 February 2020 (11:50:11 CET)
The high mutation rate of human immunodeficiency virus type 1 (HIV-1) plays a major role in treatment resistance from the development of vaccines to long-lasting drugs. In addressing the crux of the issue, various attempts to estimate the mutation rate of HIV-1 resulted in a large range of 10-5 - 10-3 errors/bp/cycle due to the use of different types of investigation methods. In this review, we discuss the different assay methods, their findings on the mutation rates of HIV-1 and how the location of these mutations can be further analyzed for their potential allosteric effects to reveal potentially new inhibitors with different pharmacodynamics that can be used to circumvent fast occurring HIV drug resistance. Given that HIV is one of the fastest mutating viruses, it is a good model for comprehensive study of its mutations that can give rise to much horizontal understanding towards overall viral drug resistance as well as emerging viral diseases.
REVIEW | doi:10.20944/preprints201712.0052.v1
Subject: Biology, Other Keywords: cell programming; stress resistance; gene overexpression; radiation; oxidative stress; chemical genotoxins; malignant transformation; diversity of mechanisms
Online: 9 December 2017 (13:26:14 CET)
Different organisms, cell types, and even similar cell lines can dramatically differ in resistance to genotoxic stress. This testifies to the wide opportunities for genetic and epigenetic regulation of stress resistance. These opportunities could be used to increas the effectiveness of cancer therapy, develop new varieties of plants and animals, and search for new pharmacological targets to enhance human radioresistance, for example, for -manned deep space expeditions. Based on the comparison of transcriptomic studies in cancer cells, in this review we propose that there is a high diversity of genetic mechanisms of development of genotoxic stress resistance. This review focused onpossibilities and limitations of the proposed regulation of the resistance of normal cells whole organisms to genotoxic and oxidative stress by overexpressing of stress-response genes. Moreover, the existing experimental data on the effect of such overexpression on the resistance of cells and organisms to various genotoxic agents has been analyzed and systematized. We suggest that the recent advances in the development of multiplex and highly customizable gene overexpression technology that utilizes the mutant Cas9 protein and the wealth of available data on gene functions and their signal networks open new opportunities for research in this field.
REVIEW | doi:10.20944/preprints202209.0454.v1
Subject: Biology, Entomology Keywords: CRISPR-Cas technology; pest management; plant stress resistance; insect resistance
Online: 29 September 2022 (07:08:41 CEST)
Global crop yield and food security are being threatened by phytophagous insects. Innovative methods are required to increase agricultural output while reducing reliance on hazardous synthetic insecticides. It appears to be quite effective at reducing production costs and boosting farm profitability to use the ground-breaking CRISPR-Cas technology to create plants that are insect resistant. In contrast, this new technique can modify an insect's genome to either produce gene drive or get beyond an insect's tolerance to various insecticides. This paper reviews and critically discusses the use of CRISPR-Cas genome editing technology in long-term insect pest management. The emphasis of this review is on the prospective uses of the CRISPR-Cas system for insect stress management in crop production by creating genome-edited crops and insects. The potential and difficulties of using CRISPR-Cas technology to reduce pest stress in crop plants are critically examined and discussed.
Subject: Medicine & Pharmacology, Allergology Keywords: antimicrobial resistance; antimicrobial stewardship; antiviral resistance; antibacterial resistance; antimalarial resistance; antifungal resistance; One Health; Uganda
Online: 14 April 2021 (12:57:40 CEST)
The global burden of antimicrobial resistance is on the rise, resulting in higher morbidity and mortality in our communities. The spread of antimicrobial resistance in the environment and development of resistant microbes is a challenge to the control of antimicrobial resistance. Approaches, such as antimicrobial stewardship programmes, and enhanced surveillance, have been devised to curb its spread. However, particularly in lower- and middle-income countries, the overall extent of antimicrobial resistance, and knowledge on on-going surveillance, stewardship or investigation efforts, re often poorly understood. This study aimed to look at the efforts that have been undertaken to combat antimicrobial resistance in Uganda as a means of establishing an overview of the situation, to help inform future decisions. We conducted a systematic literature review of the PubMed database to assess the efforts that have been done in Uganda to investigate and combat antimicrobial resistance. A search combining keywords associated with antimicrobial resistance were used to look up relevant studies between 1995 and 2020 on surveillance of antimicrobial resistance in Uganda, and susceptibility of microbes to different drugs. The search yielded 430 records, 163 of which met the inclusion criteria for analysis. The studies were categorized according to country and region, the type of antimicrobial resistance, context of the study, study design and outcome of the study. Antibacterial resistance and antimalarial resistance had the most published studies while antiviral and antifungal resistance each were represented by very few studies. Most studies were conducted in humans and hospital settings, with very few in veterinary and One Health contexts. The results from our work can inform public health policy on antimicrobial stewardship as it contributes to understanding the status of antimicrobial resistance surveillance in Uganda, and can also help to guide future research efforts. Notably, a One Health approach needs to be followed with re-spect to surveillance of antimicrobial resistance to better understand the mechanisms of resistance transfer across the human-animal–environment interface, including additional investigation in antiviral and antifungal resistance.
Subject: Biology, Other Keywords: stress granules; G3BP1; G3BP2; Caprin-1; USP10; TIA1; TIAR; cancer prognosis; biomarker; metastasis; resistance; cell death; pro-survival properties
Online: 7 April 2020 (01:56:12 CEST)
Stress Granules formation is a pro-survival mechanism helping cells to cope with environmental challenges. Stress Granules have been studied for two decades in fundamental research, and are now being examined in the context of human pathogenesis. Here, we review studies highlighting stress granules’ involvement in cancer development through translational pattern modification.
REVIEW | doi:10.20944/preprints202007.0393.v1
Subject: Life Sciences, Microbiology Keywords: Enterococcus; antibiotic resistance; vancomycin resistance; public health; nosocomial opportunists
Online: 17 July 2020 (15:32:54 CEST)
Enterococci are gastrointestinal commensals whose hardiness allowed them to colonize very diverse environments, including soils, water, food and feed. This ability to overcome adverse conditions makes enterococci problematic once they colonize hospital niches. Together with the malleability of their genomes, the capacity to acquire and disseminate determinants of antibiotic resistance have contributed to convert what was once just another opportunistic pathogen into a first-class clinical problem. This review discusses the dimension of the emergence of enterococcal resistance to key antimicrobial agents, the dissemination of this resistance and its significance in terms of public health, with the aim of raising the awareness to the need to devise and implement monitoring programmes and effective antibiotic usage guidelines.
ARTICLE | doi:10.20944/preprints201712.0199.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: IBD; intestinal barrier; Lactobacillus reuteri; Lactobacillus acidophilus; Trans Epithelial Electrical Resistance (TEER)
Online: 29 December 2017 (08:36:36 CET)
Maintenance of intestinal barrier integrity is crucial for preventing inflammatory bowel diseases (IBDs) onset and exacerbations. In this work we study the effect of a fixed combination of Lactobacillus reuteri and Lactobacillus acidophilus and herbal extracts in an in vitro inflammation experimental model. Caco-2 cell monolayer was exposed to INF-γ+TNF-α or to LPS; Trans Epithelial Electrical Resistance (TEER) and paracellular permeability were investigated. ZO-1 and occludin tight junctions (TJs) were also investigated by mean of immunofluorescence. The pre-treatment with the fixed combination of probiotics and herbal extracts prevented the inflammation-induced TEER decrease, paracellular permeability increase and TJs translocation. In summary the fixed combination of probiotics and herbal extracts investigated in this research was found to be an interesting candidate for targeting the re-establishment of intestinal barrier function in IBDs conditions.
TECHNICAL NOTE | doi:10.20944/preprints201912.0216.v1
Subject: Life Sciences, Microbiology Keywords: Antimicrobial resistance; intestinal carriage; detection; extended-spectrum beta-lactamase; carbapenem resistance; colistin resistance; ciprofloxacin resistance; vancomcin resistance; Enterobacterales; enterococci
Online: 16 December 2019 (11:34:12 CET)
The i-4-1-Health project is a One Health project on the prevalence and spread of antimicrobial resistance in the human and veterinary domain in the Dutch-Belgian cross-border region. This paper describes the main components of the laboratory protocol that was developed to standardise the microbiological methods used for the detection of intestinal carriage of highly-resistant microorganisms.
ARTICLE | doi:10.20944/preprints201610.0119.v1
Online: 27 October 2016 (11:50:52 CEST)
Rosette caused by rose rosette virus (RRV) is the most devastating malady of rose in the United States. Because of the recent discovery of the virus and the completion of Koch’s postulates all assumptions about the disease are based on visual observations of material that may or may have not been infected by the virus. This study addresses several aspects of virus and disease epidemiology. Twenty rose genotypes were screened for mite and/or virus resistance. Phyllocoptes fructiphilus the only known vector of RRV, was able to establish, lay eggs and develop to nymphs and adults in all genotypes. ‘Stormy Weather’ shows resistance to the virus as assessed by both mite and cleft-grafting transmission experiments. The acquisition/latent and inoculation access periods were studied revealing long acquisition/latent periods but rapid inoculation time frames. The outputs of this study will assist in the better management of the vector and the disease. The resistant genotype identified could be used in areas with high disease pressure to minimize spread and for identification of the mechanisms behind resistance or as breeding material to incorporate virus resistance to new cultivars. The short inoculation access period indicates that chemical control for the vector may be a challenging undertaking.
ARTICLE | doi:10.20944/preprints202203.0350.v1
Subject: Biology, Entomology Keywords: insecticide resistance; resistance monitoring; method validation; WHO tube
Online: 25 March 2022 (15:40:56 CET)
Accurately monitoring insecticide resistance in target mosquito populations is important to combating malaria and other vector-borne diseases, and robust methods are key. The “WHO susceptibility bioassay” has been used for +60 years: mosquitoes of known physiological status are exposed to a discriminating concentration of insecticide. Several changes to the test procedures have been made historically which may seem minor but could impact bioassay results. The published test procedures and literature for this method were reviewed for methodological details. Areas where there was room for interpretation in the test procedures or where the test procedures were not being followed were assessed experimentally for impact on bioassay results: covering or uncovering of the tube end during exposure, number of mosquitoes per test unit, and mosquito age. Many publications do not cite the most recent test procedures, methodological details are reported which contradict the test procedures referenced or methodological details are not fully reported. As a result, the precise methodology is unclear. Experimental testing showed that using fewer than the recommended 15-30 mosquitoes per test unit significantly reduced mortality, covering the exposure tube had no effect, and using mosquitoes older than 2-5 days old increased mortality, particularly in the resistant strain. Recommendations are made for better reporting of experimental parameters.
REVIEW | doi:10.20944/preprints202203.0103.v1
Subject: Biology, Plant Sciences Keywords: plant immune response; reactive oxygen species; salicylic acid; reactive oxygen species-salicylic acid crosstalk; programmed cell death; hypersensitive response-conferred resistance; RBOH NADPH oxidases; chloroplastic redox state; biosensors; precision transcriptomics
Online: 7 March 2022 (14:46:28 CET)
One of the earliest hallmarks of plant immune response is production of reactive oxygen spe-cies (ROS) in different subcellular compartments, which regulate plant immunity. A suitable equilibrium, which is crucial to prevent ROS over-accumulation leading to oxidative stress, is maintained by salicylic acid (SA), a chief regulator of ROS. However, ROS are not only acting downstream of SA signaling, but were also proposed to be a central component of a self-amplifying loop that regulates SA signaling as well as the interaction balance between dif-ferent phytohormones. The exact role of this crosstalk, the position where SA interferes with ROS signaling and ROS interferes with SA signaling and the outcome of this regulation depend on the origin of ROS but also on the pathosystem. The precise spatiotemporal regulation of or-ganelle specific ROS and SA levels determine the effectiveness of pathogen arrest and is there-fore crucial for a successful immune response. However, the regulatory interplay behind still remain poorly understood, as up till now, the role of organelle specific ROS and SA in HR-conferred resistance has mostly been studied by altering the level of a single component. In order to address these aspects, a sophisticated combination of research methods for monitoring the spatiotemporal dynamics of key players and transcriptional activity in plants is needed, and will most probably consist of biosensors and precision transcriptomics.
REVIEW | doi:10.20944/preprints202005.0232.v1
Subject: Life Sciences, Microbiology Keywords: phage resistance; phage therapy; vConTACT 2.0; phage resistance ecology; bacteriophages
Online: 14 May 2020 (08:09:04 CEST)
: As antibiotic resistance undermines efforts to treat bacterial infections, phage therapy is being increasingly considered as an alternative in clinical settings and agriculture. However, a major concern in using phages is that pathogens will develop resistance to the phage. Due to the constant evolutionary pressure by phages, bacteria have evolved numerous mechanisms to block infection. If we determine the most common among them, we could use this knowledge to guide phage therapeutics. Here we compile data from 88 peer-reviewed studies where phage resistance was experimentally observed and linked to a bacterial gene, then assessed these data for patterns. In total, 141 host genes were identified to block infection against one or more of 80 phages (representing five families of the Caudovirales) across 16 microbial host genera. These data suggest that bacterial phage resistance is diverse, but even well-studied systems are understudied, and there are gaping holes in our knowledge of phage resistance across lesser-studied regions of microbial and viral sequence space. Fortunately, scalable approaches are newly available that, if broadly adopted, can provide data to power ecosystem-aware models that will guide harvesting natural variation towards designing effective, broadly applicable phage therapy cocktails as an alternative to antibiotics.
ARTICLE | doi:10.20944/preprints201806.0290.v1
Subject: Life Sciences, Microbiology Keywords: urine; resistance; antibiotic; nitrofurantoin; Mozambique
Online: 19 June 2018 (10:33:14 CEST)
Urinary tract infections are a major cause of morbidity and mortality in Mozambique. They are sometimes treated empirically with nitrofurantoin. However, little is known about this antibiotic’s performance and bacterial resistance in the country. This study analyzed the results of nitrofurantoin sensitivity tests requested in the Central Hospital of Maputo during 2012 and 2013. As result, 181 samples were tested and most cases (66.9%) showed absolute sensitivity but there were considerable cases of resistance (29.8%). Morganella morganii was the only bacteria presenting no absolute or intermediate resistance. The sensitivity was also high in the case of Escherichia coli (90%) and Gram-negative bacteria (66.7%). Serratia marcescens was mostly resistant (64.3%). The remaining bacteria showed inconclusive results. Thus they shall be subjected to a sensitivity test before prescription. Factors such as seasonality, patients’ sex and urine transparency did not seem to be reliable indicators of microbial resistance in the urine. Yet, a longer time span (over 5 years) might be sufficient for the sensitivity profile to change.
ARTICLE | doi:10.20944/preprints202201.0329.v1
Subject: Life Sciences, Other Keywords: metabolic resistance; drought tolerance; threshold FTSW; stomatal closure; EPSPS gene amplification; S-metolachlor resistance; glyphosate resistance
Online: 21 January 2022 (13:37:55 CET)
Drought events are predicted to become more prevalent in the future. Evaluating the performance of herbicide-resistant and susceptible weed ecotypes to progressive drought can provide insights into whether resistance trait(s) increased or reduced the fitness of a resistant population. Two experiments were conducted in the greenhouse between January and May 2021 to evaluate drought tolerance differences between Palmer amaranth accessions resistant to S-metolachlor or glyphosate and their susceptible counterparts. The accessions used were: S-metolachlor-resistant (17TUN-A), a susceptible standard (09CRW-A), and glyphosate-resistant (22 to 165 EPSPS copies) and glyphosate-susceptible (3 to 10 EPSPS copies) plants from accession 16CRW-D. Daily transpiration of each plant was measured. The daily transpiration rate was converted to normalized transpiration ratio (NTR) using a double-normalization procedure. The daily soil water content was expressed as a fraction of transpirable soil water (FTSW). The threshold FTSW (FTSWcr), after which NTR decreases linearly, was estimated using a two-segment linear regression analysis. The data showed differences between S-metolachlor- resistant and -susceptible accessions (P ≤ 0.05). The FTSW remaining in the soil at the breakpoint for the S-metolachlor-susceptible accession (09CRW-A) was 0.17±0.007. The FTSW remaining in the soil at the breakpoint for the S-metolachlor-resistant accession (17TUN-A) was 0.23±0.004. Although the mechanism endowing resistance to S-metolachlor might have contributed to increased drought tolerance, follow-up experiments are needed to verify this finding. Increased EPSPS copy number did not improve drought tolerance of Palmer amaranth.
ARTICLE | doi:10.20944/preprints201907.0148.v1
Online: 10 July 2019 (11:07:07 CEST)
Tomato is the highest-value fruit/vegetable crop worldwide. However, the quality and yield of tomatoes are severely affected by late blight. MicroRNA482s (miR482s) are involved in plant immune system. In this study, miR482c was transiently and stably overexpressed in tomatoes in transgenic plants to explore its mechanism in tomato resistance against late blight. Tomato in transgenic plants transiently overexpressed miR482c displayed larger lesion area than the control plants upon infection. Furthermore, compared with the WT tomato plants, the transgenic tomato plants stably overexpressing miR482c displayed decreased expression of target genes accompanied by lower POD, SOD, and PAL activity activities and higher MDA content, thereby leading to a decline in the ROS scavenging ability and aggravating the damage of lipid peroxidation product accumulation on the cell membrane, eventually enhancing plant susceptibility. This finding indicates that miR482c may act as a negative regulator in tomato resistance by regulating NBS-LRR expression levels and ROS levels.
REVIEW | doi:10.20944/preprints202010.0217.v1
Online: 12 October 2020 (09:49:33 CEST)
Phytopathogenic oomycetes are known to infect a host plant successfully due to their ability to secrete a set of protein effectors. Of interest to many researchers are effectors with the N-terminal RxLR motif (Arginine-any amino acid-Leucine-Arginine). Owing to the genome sequencing, we can now comprehend the high level of diversity among oomycete effectors, and similarly, their conservation within and among species core RxLR effectors (CREs). Currently, there are a couple of putative CREs that have been identified in oomycetes. The functional characterization of these CREs proposes their virulence role with the potential of targeting central cellular processes that are conserved across diverse plant species. This could be harnessed in engineering plants for broad-spectrum and durable resistance.
REVIEW | doi:10.20944/preprints202301.0386.v1
Subject: Life Sciences, Microbiology Keywords: Antibiotic resistance; bacteria; gene; developing countries
Online: 23 January 2023 (01:54:28 CET)
Antibiotic resistance is a major public health issue that requires a multifaceted approach. One potential source of antibiotic-resistant bacteria is wastewater in developing countries, which often lacks proper treatment infrastructure and can release high levels of antibiotics and antibiotic-resistant bacteria into the environment. This review article summarizes current knowledge on strategies to combat antibiotic resistance in wastewater in developing countries. Our review highlights the importance of improving wastewater treatment infrastructure to effectively remove antibiotics and antibiotic-resistant bacteria, implementing measures to reduce the release of antibiotics into the environment, and monitoring and surveillance to track the presence and spread of antibiotic-resistant bacteria in wastewater. We also discuss the potential challenges and barriers to implementing these strategies and the need for further research to determine their effectiveness in real-world settings. Overall, this review highlights the need for a comprehensive approach to address antibiotic resistance in wastewater in developing countries and underscores the importance of addressing this issue to protect public health.
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: EGFR-mutated non-small cell lung cancer; EGFR-TKI; intrinsic resistance; resistance mechanisms
Online: 22 April 2019 (11:08:42 CEST)
Activating mutations in the Epidermal Growth Factor Receptor gene occur as early cancer-driving clonal events in a subset of patients with non-small cell lung cancer (NSCLC) and result in increased sensitivity to EGFR-tyrosine-kinase-inhibitors (EGFR-TKIs). Despite very frequent and often prolonged clinical response to EGFR-TKIs, virtually all advanced EGFR-mutated (EGFRM+) NSCLCs inevitably acquire resistance mechanisms and progress at some point during treatment. Additionally, 20-30% of patients do not respond or respond for a very short time (< 3 months) because of intrinsic resistance. While several mechanisms of acquired EGFR-TKI-resistance have been determined analyzing tumor specimens obtained at disease progression, the factors causing intrinsic TKI-resistance are less understood. However, recent comprehensive molecular-pathological profiling of advanced EGFRM+ NSCLC at baseline has illustrated the co-existence of multiple genetic, phenotypic, and functional mechanisms that may contribute to tumor progression and cause intrinsic TKI-resistance. Several of these mechanisms have been further corroborated by preclinical experiments. Intrinsic resistance can be caused by mechanisms inherent EGFR or by EGFR-independent processes, including genetic, phenotypic or functional tumor changes. This comprehensive review describes the identified mechanisms connected with intrinsic EGFR-TKI-resistance and differences and similarities with acquired resistance and among clinically implemented EGFR-TKIs of different generations. Additionally, the review highlights the need for extensive pre-treatment molecular profiling of advanced NSCLC for identifying inherently TKI-resistant cases and designing potential combinatorial targeted strategies to treat them.
REVIEW | doi:10.20944/preprints202008.0313.v2
Subject: Biology, Anatomy & Morphology Keywords: drug resistance; natural diversity; C. elegans; anthelmintics
Online: 25 November 2020 (14:47:29 CET)
Anthelmintic drugs are the major line of defense against parasitic nematode infections, but the arsenal is limited and resistance threatens sustained efficacy of the available drugs. Discoveries of the modes of action of these drugs and mechanisms of resistance have predominantly come from studies of a related non-parasitic nematode species, Caenorhabditis elegans, and the parasitic nematode Haemonchus contortus. Here, we discuss how our understanding of anthelmintic resistance and modes of action came from the interplay of results from each of these species. We argue that this “cycle of discovery”, where results from one species inform the design of experiments in the other, can use the complementary strengths of both to understand anthelmintic modes of action and mechanisms of resistance.
ARTICLE | doi:10.20944/preprints201812.0362.v1
Subject: Keywords: Antibiotic resistance, efflux pump inhibitors, Escherichia coli, efflux pumps, multidrug resistance, Staphylococcus aureus
Online: 31 December 2018 (09:55:32 CET)
Bacterial antibiotic resistance has become a major global health concern. One of the main reasons for the development of multi-drug resistance properties in bacteria is due to the bacterial efflux pump systems. They are important transport proteins, mainly involved in the removal of toxic substrates like antibiotics from inner cell environment. These pumps are responsible for the intrinsic ability of bacteria to get resistant to the antibiotic. Various types of efflux pumps are present in the Gram-positive and Gram-negative bacteria. Plant-derived products like Capsaicin, Olympicin A, and Indirubicin were found to be inhibitors of an efflux pump in Staphylococcus aureus similarly Ursolic acid derivatives; Daidzein and Lanatoside C were plant-derived inhibitors of an efflux pump in Escherichia coli. In this review detail information have been provided about efflux pump inhibitors that have been found to be effective in the Gram-positive bacteria and Gram-negative bacteria. The aim of this review is to focus on the role of plant-derived compounds as effective efflux pumps inhibitors with reference to mainly Staphylococcus aureus and Escherichia coli.
REVIEW | doi:10.20944/preprints202301.0081.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Phytocytokines; Induced resistance; Priming; Plant Immunity; Peptides
Online: 4 January 2023 (12:07:11 CET)
The plant immunity system is more and more revisited and new elements and roles are attributed to participate in the response to biotic stress. New terminology is also applied trying to identify different players in the whole scenario of immunity: Phytocytokines are one of those elements that are gaining more attention due the characteristics of processing and perception, and showing they are part of a big family of compounds that can amplify the immune response. This review aims to highlight the last findings about the role of phytocytokines in the whole immune response on biotic stress, including basal and adaptive immunity, and to expose the complexity in their action in plant perception and signaling events.
ARTICLE | doi:10.20944/preprints202208.0302.v1
Subject: Biology, Plant Sciences Keywords: Verticillium wilt; cotton; transmembrane protein; resistance; plant immunity
Online: 17 August 2022 (05:28:04 CEST)
Verticillium wilt (VW) is a soil borne fungal diseases caused by Verticillium dahliae Kleb, and lead to serious damage to cotton production annually in the world. In our previous study, a transmembrane protein 214 protein (TMEM214) gene associated with VW resistance was map-based cloned from Gossypium barbadense (G. barbadense). TMEM214 proteins are a kind of transmembrane protein, but their function in plants is rarely studied. To reveal the function of TMEM214s in VW resistance, all six TMEM214s were cloned from G. barbadense in this study. These genes were named as GbTMEM214-1, GbTMEM214-4 and GbTMEM214-7 according to their location on the chromosomes, and the encoded proteins are all located on cell membrane. TMEM214 genes were all induced by Verticillium dahliae inoculation and showed significant differences between resistant and susceptible varieties, but the expression patterns of GbTMEM214s under different hormone treatments were significantly different. Virus-induced gene silencing analysis showed the resistance to VW of GbTMEM214s-silenced lines decreased significantly, which further proves the important role of GbTMEM214s in the resistance to Verticillium dahliae. Our study provides an insight into the involvement of GbTMEM214s in VW resistance, which was helpful to better understand the disease resistance mechanism of plants.
REVIEW | doi:10.20944/preprints202204.0004.v1
Subject: Life Sciences, Microbiology Keywords: Neisseria gonorrhea; Zoliflodacin; Covid-19; Antibiotic-resistance; Treatment
Online: 1 April 2022 (07:26:28 CEST)
Background: Neisseria gonorrhea is a gram negative diplococci leads to sexually transmitted infection. N.gonorrhoeae is an obligate human pathogen that causes infection to the mucus-secreting epithelial cells both in male and female. In 2017 the centre of disease control and World Health Organization published the list of global priority pathogens-12 with denting therapeutic options, including antibiotic-resistant N. gonorrhoeae. Aim: During the covid-19 pandemic, excessive use of antibiotics is occurring which has lead to its resistance. The infection is widespread and intractable. If this happens, more people will be left with an incurable infection which may cause serious health problems. The possibility of untreatable gonorrhea is emerging larger, and hence, it is the need of an hour to develop new drug for treating it Methods and material: We characterized thoroughly zoliflodacin antibiotic, its clinical trials and effect on human health by using different keywords like “zoliflodacin”, “covid-19”, “clinical trials” from different data sources like Pub-Med, Google-Scholar, and Science-Direct. Result: Zoliflodacin targets antibiotic-resistant gonorrhea. Zoliflodacin shows therapeutic approach against N. gonorrhea. It acts by inhibiting bacterial type 2 topoisomerase with binding site in bacterial gyrase. It shows promising results against N. gonorrhea. Zoliflodacin is effective in treating gonococcal urogenital and rectal infection. Discussion: Antibiotic is the only option to treat N. gonorrhea. There is no vaccine available to treat gonorrhea. The new drug, zoliflodacin, specifically targets antibiotic-resistant gonorrhea. This is giving a hope to researchers. In this study, we elaborate the discovery of zoliflodacin, its mechanism of action, the current clinical trials, and the effectiveness of zoliflodacin.
ARTICLE | doi:10.20944/preprints202010.0428.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Injured tissue; Tissue remodeling; Treatment resistance; Radioisotope; Cancer stroma
Online: 21 October 2020 (10:36:25 CEST)
Background: In treatment-refractory cancers, tumor tissues damaged by therapy initiate the repair response; therefore, tumor tissues must be exposed to an additional burden before successful repair. We hypothesized that an agent recognizing a molecule that responds to anticancer treatment–induced tissue injury could deliver an additional antitumor agent including a radionuclide to damaged cancer tissues during repair. We selected the extracellular matrix glycoprotein tenascin-C (TNC) as such a molecule, and three antibodies recognizing human and murine TNC were employed to evaluate X-irradiation–induced changes in TNC uptake by subcutaneous tumors. Methods: TNC expression was assessed by immunohistochemical staining of BxPC-3 tumors treated with or without X-irradiation (30 Gy) for 7 days. Antibodies against TNC (3-6, 12-2-7, TDEAR) and a control antibody were radiolabeled with 111In and injected into nude mice having BxPC-3 tumors 7 days after X-irradiation, and temporal uptake was monitored for an additional 4 days by biodistribution and single-photon emission computed tomography with computed tomography (SPECT/CT) studies. Intratumoral distribution was analyzed by autoradiography. Results: The immunohistochemical signal for TNC expression was faint in nontreated tumors but increased and expanded with time until day 7 after X-irradiation. Biodistribution studies revealed increased tumor uptake of all three 111In-labeled antibodies and the control antibody. However, a statistically significant increase in uptake was evident only for 111In-labeled 3-6 (35%ID/g for 30 Gy vs. 15%ID/g for 0 Gy at day 1, P < 0.01; ID, injected dose), whereas limited changes in 111In-labeled TDEAR2, 12-2-27, and control antibody were observed (several %ID/g for 0 and 30 Gy). Serial SPECT/CT imaging with 111In-labeled 3-6 or control antibody provided consistent results. Autoradiography revealed noticeably stronger signals in irradiated tumors injected with 111In-labeled 3-6 compared with each of nonirradiated tumors and the control antibody. The signals were observed in TNC-expressing stroma. Conclusion: Markedly increased uptake of 111In-labeled 3-6 in irradiated tumors supports our concept that an agent, such as an antibody, that recognizes a molecule, such as TNC, involved in tissue-injury repair could enhance drug delivery to therapy-experienced tumor tissues. The combination of antibody 3-6 coupled to a tumoricidal drug and conventional therapy has the potential to achieve better outcomes for patients with refractory cancer.
REVIEW | doi:10.20944/preprints202107.0203.v1
Online: 8 July 2021 (13:30:31 CEST)
Clopidogrel is one of the thienopyridine antiplatelet drugs commonly used as a prophylactic medication to prevent coagulation in vessels and cardiovascular events. The molecule of clopidogrel is metabolized in the liver via phase-I and phase-II metabolism pathways. The sulfenic acid clopidogrel metabolite undergoes phase-II metabolism through conjugation with glutathione by the glutathione-s-transferase (GST) to form a glutathione conjugate of clopidogrel (inactive metabolite). A glutaredoxin enzyme removes the glutathione conjugated with clopidogrel to form cis-thiol-clopidogrel. This review focused on the polymorphisms of genes related to phase-II metabolism during the clopidogrel bioactivation process. Overall, no well-controlled studies were done about the relationship between the clopidogrel bioactivation process and genes related to phase-II metabolism’s enzymes. Nevertheless, some polymorphisms of G6PD, GCLC, GCLM, GSS, GST, GSR, HK, and GLRX genes could be responsible for clopidogrel resistance due to low glutathione conjugate or glutaredoxin plasma levels. Studies needed to be concerned with the relationship between clopidogrel resistance and phase-II metabolism issues in the near future.
REVIEW | doi:10.20944/preprints201808.0306.v1
Subject: Biology, Other Keywords: Candida glabrata, drug resistance, tolerance, FKS, MSH2, echinocandin, azole
Online: 17 August 2018 (12:43:43 CEST)
Candida glabrata has thoroughly adapted to successfully colonize human mucosal membranes and survive in vivo pressures prior to and during antifungal treatment. Out of all the medically relevant Candida species, C. glabrata has emerged as a leading cause of azole, echinocandin, and multidrug (MDR: azole + echinocandin) adaptive resistance. Neither mechanism of resistance is intrinsic to C. glabrata, since stable genetic resistance depends on mutation of drug target genes, FKS1 and FKS2 (echinocandin resistance), and a transcription factor, PDR1, which controls expression of major drug transporters, such as CDR1 (azole resistance). However, another hallmark of C. glabrata is the ability to withstand drug pressure both in vitro and in vivo prior to stable ‘genetic escape’. Additionally, these resistance events can arise within individual patients, which underscores the importance of understanding how this fungus is adapting to its environment and to drug exposure in vivo. Here, we explore the evolution of echinocandin resistance as a multistep model that includes general cell stress, drug adaptation (tolerance), and genetic escape. The extensive genetic diversity reported in C. glabrata will be highlighted.
REVIEW | doi:10.20944/preprints201809.0435.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Acute Myeloid Leukemia; FLT3; Tyrosine kinase inhibitors; resistance
Online: 21 September 2018 (10:28:34 CEST)
Identification of recurrent driver mutations in genes encoding tyrosine kinases has resulted in the development of molecularly targeted strategies designed to improve the outcomes for patients diagnosed with acute myeloid leukemia (AML). The receptor tyrosine kinase FLT3, is the most commonly mutated gene in AML, with internal tandem duplications within the juxtamembrane domain (FLT3-ITD) or missense mutations in the tyrosine kinase domain (FLT3-TKD), present in 30%-35% of AML patients at diagnosis. An established driver mutation and marker of poor prognosis, the FLT3 tyrosine kinase has emerged as an attractive therapeutic target, and thus has encouraged the development of FLT3 tyrosine kinase inhibitors (TKIs). However, the therapeutic benefit of FLT3 inhibition, particularly as monotherapy, frequently results in the development of treatment resistance and disease relapse. Commonly, FLT3 inhibitor resistance is induced by the emergence of secondary lesions in the FLT3 gene, particularly in the second tyrosine kinase domain at residue Asp835 (D835) to form a ‘dual mutation’ (ITD-D835). Individual FLT3-ITD and FLT3-TKD mutations influence independent signaling cascades however, currently little is known which divergent signaling pathways are controlled by each of these FLT3 specific mutations, particularly in the context of patients harboring dual ITD-D835 mutations. This review provides a comprehensive analysis of the known discrete and cooperative signaling pathways regulated by each of the FLT3 specific mutations, as well as the therapeutic approaches that hold the most promise for development of more durable and personalized therapeutic approaches targeting mutant FLT3, to improve the treatment of AML.
ARTICLE | doi:10.20944/preprints201807.0199.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: ALS-inhibitors; horseweed; multiple-resistance; alternative chemical control
Online: 11 July 2018 (11:56:59 CEST)
Conyza canadensis is a species invading large agricultural areas throughout the world, mainly to its ability to evolve herbicide resistance. Specifically, in Hungary, extensive areas have been infested by this species due to the difficulty in controlling it with glyphosate. To corroborate this fact as resistance and not as an incorrect herbicide application, eight suspicious glyphosate-resistant C. canadensis populations from different Hungarian regions were studied. In dose-response assays with glyphosate, the LD50 and GR50 values indicated that populations 1 to 5 were resistant to this herbicide (H-5 population the most resistant). Besides, the shikimic acid accumulation tests corroborated the results observed in the dose-response assays. 11 alternative herbicides from 6 different mode of action (MOA) were applied at field doses as control alternatives on populations H-5 and H-6 (both in the same regions). The H-5 population showed an unexpected resistance to flazasulfuron (ALS-inhibitor). The ALS enzyme activity studies indicated that the I50 for H-5 was 63.3 fold higher compared to its correspondent susceptible population (H-6). Therefore, the H-5 population exhibited multiple-resistance to flazasulfuron and glyphosate, being the first case reported in Europe for this two MOA. For that reason, the other herbicides with different MOA have to be tested here.
ARTICLE | doi:10.20944/preprints202108.0041.v1
Subject: Physical Sciences, Acoustics Keywords: chip-nanocalorimetry; ultrafast nanocalorimetry; interfacial thermal resistance
Online: 2 August 2021 (13:08:06 CEST)
Ultrafast chip nanocalorimetry opens up remarkable possibilities in materials science by allowing samples to be cooled and heated at extremely high rates. Due to heat transfer limitations, controlled ultrafast cooling and heating can only be achieved for tiny samples in calorimeters with a micron-thick membrane. Even if ultrafast heating can be controlled under quasi-adiabatic conditions, ultrafast controlled cooling can be performed if the calorimetric cell is located in a heat-conducting gas. It was found that the maximum possible cooling rate increases as 1/r0 with decreasing radius r0 of the hot zone of the membrane. The possibility of increasing the maximum cooling rate with decreasing r0 was successfully implemented in many experiments. In this regard, it is interesting to answer the question: what is the maximum possible cooling rate in such experiments if r0 tends to zero? Indeed, on submicron scales, the mean free path of gas molecules lmfp becomes comparable to r0, and the temperature jump that exists at the membrane/gas interface becomes significant. Considering the limitation associated with thermal resistance at the membrane/gas interface and considering the transfer of heat through the membrane, we show that the controlled cooling rate can reach billions of K/s, up to 1010 K/s.
REVIEW | doi:10.20944/preprints202212.0453.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: wheat; resistance; leaf rust; genetic loci; genome-wide
Online: 23 December 2022 (08:11:48 CET)
Due to the global warming and dynamic changes in pathogenic virulence, leaf rust caused by Puccinia triticina has greatly expanded its epidermic region and become a severe threat to global wheat production. Genetic bases of wheat resistance to leaf rust mainly relies on the leaf rust resistance (Lr) gene or quantitative trait locus (QLr). Although these genetic loci have been insensitively studied during the last two decades, an updated overview of Lr/QLr in a genome-wide level is urgently needed. This review summarized recent progresses in genetic studies of wheat resistance to leaf rust. Wheat germplasms with great potentials in genetic improvement of resistance to leaf rust were highlighted. Key information about the genetic loci carrying Lr/QLr were summarized. A genome-wide chromosome distribution map for all the Lr/QLr was generated based on the released wheat reference genome. In conclusion, this review has provided valuable sources for both wheat breeders and researchers to understand the genetics of resistance to leaf rust in wheat.
REVIEW | doi:10.20944/preprints202203.0262.v1
Subject: Life Sciences, Microbiology Keywords: Keywords: antifungal; azole; synergy; mycosis; resistance; Candida; dermatophytes; natural products
Online: 18 March 2022 (07:04:16 CET)
Fungal infections impact the lives of at least 12 million people every year, killing over 1.5 million. Wide-spread use of fungicides and prophylactic antifungal therapy have driven resistance in many serious fungal pathogens, and there is an urgent need to expand the current antifungal ar-senal. Recent research has focused on improving azoles, our most successful class of antifungals, by looking for synergistic interactions with secondary compounds. Synergists can co-operate with azoles by targeting steps in related pathways, or they may act on mechanisms related to re-sistance like active efflux or on totally disparate pathways or processes. A variety of sources of potential synergists have been explored, including pre-existing antimicrobials, pharmaceuticals approved for other uses, bioactive natural compounds and phytochemicals, and novel synthetic compounds. Synergy can successfully widen the antifungal spectrum, decrease inhibitory dosag-es, reduce toxicity, and prevent the development of resistance. This review highlights the diversity of mechanisms that have been exploited for the purposes of azole synergy and demonstrates that synergy remains a promising approach for meeting the urgent need for novel antifungal strate-gies.
ARTICLE | doi:10.20944/preprints202109.0095.v1
Subject: Life Sciences, Genetics Keywords: prion; deer; PRNP; selective breeding; resistance; susceptibility; CWD
Online: 6 September 2021 (13:13:47 CEST)
Chronic wasting disease is a fatal transmissible spongiform encephalopathy (TSE) of cervids caused by a misfolded variant of the normal cellular prion protein, and is closely related to sheep scrapie. Variations in a host’s prion gene, PRNP, and its primary protein structure, dramatically affect susceptibility to specific prion disorders, and breeding for PRNP variants that prevent scrapie infection has led to steep declines in the disease in North American and European sheep. While resistant alleles have been identified in cervids, a PRNP variant that completely prevents CWD has not yet been identified. Thus, control of the disease in farmed herds traditionally relies on quarantine and depopulation. In CWD-endemic areas, depopulation of private herds becomes challenging to justify, leading to opportunities to manage the disease in situ. In the present study, we developed a selective breeding program for farmed white-tailed deer in a CWD-endemic area, focused on reducing frequencies of highly susceptible PRNP variants and introducing animals with less-susceptible variants into historically high prevalence areas. We found that breeding followed predictable Mendelian inheritance, and early data support our project’s utility in reducing CWD prevalence. This project represents a novel approach to CWD management, with future efforts building on these findings.
ARTICLE | doi:10.20944/preprints202105.0069.v1
Subject: Life Sciences, Biochemistry Keywords: Antimicrobial Resistance; Biosecurity; Egg; Nigeria; Poultry; Salmonella
Online: 5 May 2021 (15:04:41 CEST)
Salmonella remains one of the notable food-borne bacterial pathogens. It is associated with poultry and poultry products including eggs. This study investigated Salmonella distribution in eggshell and content, their antimicrobial resistance pattern, and the possible risk factors driving contamination in Ogun State, Nigeria. A total of 500 eggs (5 eggs pooled into one sample) were collected and culturally examined for the presence of Salmonella serovars. Isolates were further characterized biochemically using Microbact 20E (Oxoid) and Antimicrobial susceptibility determined by the Kirby-Bauer disk diffusion method. A total of 14 Salmonella isolates spread across 10 serovars were recovered from the 100 pooled egg samples; 10 (10%) from the market and 4 (4%) farms, 13(13%) eggshell, and 1(1%) egg content. All tested serovars were susceptible to ampicillin, chloramphenicol, florfenicol, and kanamycin. Resistance was mostly observed in sulfamethoxazole 8 (80%), followed by ciprofloxacin 5 (50%) and tetracycline 3 (30%). Sales of eggs in the market appears to be a strong factor encouraging contamination in addition to poor biosecurity and unhygienic handling of eggs on the farm.
ARTICLE | doi:10.20944/preprints201701.0098.v1
Online: 23 January 2017 (03:30:01 CET)
HER2/neu positive breast tumors predict a high mortality and comprise 25-30% of breast cancer. We have shown that Flavokawain A (FKA) preferentially reduces the viabilities of HER2 overexpressing breast cancer cell lines (i.e. SKBR3 and MCF7/HER2) versus those with less HER2 expression (i.e. MCF7 and MDA-MB-468). FKA at cytotoxic concentrations to breast cancer cell lines also has minimal effect on the growth of non-malignant breast epithelial MCF10 cells. FKA induces G2M arrest in cell cycle progression of HER2 overexpressing breast cancer cell lines through inhibition of Cdc2 and Cdc25C phosphorylation and down-regulation of Myt1 and Wee1expression leading to increased Cdc2 kinase activities. In addition, FKA induces apoptosis in SKBR3 cells by increasing the protein expression of Bim and BAX and decreasing expression of Bcl2, Bclx/L , XIAP and survivin. FKA also down-regulates the protein expression of HER-2 and inhibits AKT phosphorylation. Herceptin plus FKA treatment leads to enhanced growth inhibitory effect on HER-2 overexpressing breast cancer cell lines through down-regulation of Myt1, Wee1, Skp2, Survivin and XIAP. Our results suggest the promise of FKA as a novel apoptosis inducer and G2 checkpoint abrogating agent in combination with Herceptin for treatment of HER2 overexpressing breast cancer.
Subject: Biology, Anatomy & Morphology Keywords: Bovine respiratory disease; Pasteurella multocida; resistance; tolerance; satP.
Online: 20 July 2021 (14:48:06 CEST)
Under the pressure of fluoroquinolones, Pasteurella multocida (PM) can easily develop resistance to fluoroquinolones mediated by QRDR target mutation. It is imperative to find new drug resistance inhibitor targets to combat the rapid development of drug resistance. In order to overcome these problems, we sequenced the transcriptome of PM with different levels of resistance to ENR(0.03 μg/mL; 8 μg/mL; 32μg/Ml, Enrofloxacin). The results showed that with the increase of resistance to fluoroquinolones, the expression of satP gene was significantly up-regulated. The satP gene deletion strain and replenishment strain were constructed, and their drug resistance and tolerance were determined. The results showed that the deletion of satP gene did not affect the resistance of PM to fluoroquinolones, rather affected the time when PM developed resistance to fluoroquinolones. After 10 generations of drug induction, the MIC (minimum inhibitory concentration) of fluoroquinolones for wild strain was 64 μg/mL, while the MIC for satP gene deletion strain was only 8 μg/mL. The MDK99 test (time to kill 99% bacteria),agar diffusion test and mutation frequency test showed that the tolerance of satP gene deletion strain was significantly lower than that of wild strain. At the same time, the virulence of gene deletion strain and wild strain was tested, and about 400 times decreased virulence was observed for satP gene deletion strain. The mouse infection model confirmed that mice infected with satP gene deletion strains were more likely to be treated with ENR than mice infected with wild-type bovine PM strains. The results show that satP has potential to be a target of fluoroquinolone resistance inhibitors.
Subject: Biology, Entomology Keywords: host plant resistance; pest management; Planococcus ficus; vineyard
Online: 11 September 2019 (02:41:28 CEST)
Mealybugs cause economic loss to vineyards through physical damage, fouling fruit and leaves with honeydew, and the transmission of viruses. Planococcus ficus is one of several mealybug species in vineyards, and one that causes economic damage over a relatively large global range. To develop novel management tools, host resistance to P. ficus, which has not previously been identified for any grape cultivars, was studied. Ten grape lines (species, cultivars, and rootstocks) were evaluated for P. ficus resistance across two separate potted plant assays. Significant differences were detected among cultivars and rootstocks in the recorded number of P. ficus juveniles, adults and egg sacs. Cabernet Sauvignon and Chardonnay were two of the most susceptible grape cultivars for mealybug population growth, whereas rootstocks IAC 572, 10-17A and RS-3 all demonstrated some level of resistance. Southern fire ant (Solenopsis xyloni) was positively associated with mealybug populations, but did not have a negative effect on the observed presence of other arthropod species including potential predators.
ARTICLE | doi:10.20944/preprints201805.0076.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Oral cancer; mTOR pathway; secreted glycoprotein; drug resistance
Online: 3 May 2018 (12:47:14 CEST)
Oral cancer is a major public health burden worldwide. The lack of biomarkers for early diagnosis has increased the difficulty in managing this disease. Recent studies have reported that neutrophil gelatinase-associated lipocalin (NGAL), a secreted glycoprotein, is upregulated in various tumors. In our study we found that NGAL was significantly downregulated in primary malignant and metastatic tissues of oral cancer compared to normal tissues. The downregulation of NGAL was strongly correlated with the degree of differentiation and stage (I-IV), and can serve as a prognostic biomarker for oral cancer. Tobacco carcinogens were also found to be involved in the downregulation of NGAL. Mechanistic studies revealed that knockdown of NGAL increased oral cancer cell proliferation, survival, and migration, and also induced resistance against cisplatin. Silencing of NGAL activated mTOR signaling and reduced autophagy by the LKB1-AMPK-p53-Redd1 signaling axis. Moreover, cyclin-D1, Bcl-2, and MMP-9 were upregulated, and caspase-9 was downregulated, suggesting that silencing of NGAL increases oral cancer cell proliferation, survival, and migration. Thus, from our study it is evident that downregulation of NGAL activates the mTOR pathway and helps in the progression of oral cancer.
REVIEW | doi:10.20944/preprints202210.0066.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: structure-based studies; ABC transporter; multidrug resistance (MDR); cancer therapy
Online: 6 October 2022 (12:28:26 CEST)
The discovery of first ATP-binding cassette (ABC) transporter, whose overexpression in cancer cells is responsible for exporting anticancer drugs out of tumor cells, initiated enormous efforts to overcome tumor cell multidrug resistance (MDR) by inhibition of ABC-transporter. Because of its many physiological functions, diverse studies have been conducted on the mechanism, function and regulation of this important group of transmembrane transport proteins. In this review, we will focus on the structural aspects of this transporter superfamily. Since the resolution revolution of electron microscope, experimentally solved structures increased rapidly. A summary of the structures available and an overview of recent structure-based studies are provided. More specifically, the artificial intelligence (AI)-based predictions from AlphaFold 2 will be discussed.
Subject: Life Sciences, Biochemistry Keywords: Mollusc; selective breeding; gene editing; disease resistance; transgenesis; CRISPR/Cas9
Online: 15 October 2020 (16:06:27 CEST)
Molluscan aquaculture is a major contributor to global seafood production, but is hampered by infectious disease outbreaks which can cause serious economic losses. Selective breeding has been widely used to improve disease resistance in major agricultural and aquaculture species, and has clear potential in molluscs, albeit its commercial application remains at a formative stage. Advances in genomic technologies, especially development of cost-efficient genomic selection, have potential to accelerate genetic improvement. However, tailored approaches are required due to the distinctive reproductive and lifecycle characteristics of molluscan species. Transgenesis and genome editing, in particular CRISPR/Cas systems, have been successfully trialled in molluscs, and may further understanding and improvement of genetic resistance to disease through targeted changes to the host genome. Whole organism genome editing is achievable on a much greater scale compared to other farmed species, making genome-wide CRISPR screening approaches plausible. This review discusses the current state and future potential of selective breeding, genomic tools, and genome editing approaches to understand and improve host resistance to infectious disease in molluscs.
REVIEW | doi:10.20944/preprints202006.0174.v1
Subject: Medicine & Pharmacology, Other Keywords: Acinetobacter baumannii; colistin; tigecycline; resistance; in vivo
Online: 14 June 2020 (14:16:40 CEST)
The potential of A. baumannii for acquired resistance to last resort antibiotics (colistin and tigecycline) during treatment has important clinical implications, especially when dealing with patients failing to improve despite treatment with an active antimicrobial. However, the relevant literature remains scattered. Therefore, a systematic search was conducted in PubMed and Scopus. Several studies reported emergence of resistance to colistin or tigecycline during treatment, in most cases (86%) resulting in persistent or recurrent infections, especially in cases of emergent resistance without fitness cost. Lipopolysaccharide modification in the case of colistin and overexpression of efflux pumps in the case of tigecycline were the main mechanisms of resistance. Emergent colistin resistance is often associated with fitness cost resulting in re-emergence of the fitter and more virulent colistin susceptible strain after cessation of antibiotic pressure. Prospective studies are needed to determine the frequency of emergent resistance during treatment and its impact on patient outcomes.
REVIEW | doi:10.20944/preprints202103.0063.v1
Subject: Medicine & Pharmacology, Allergology Keywords: breast cancer, CDK inhibitors, liquid biopsy, resistance mechanisms, therapy
Online: 2 March 2021 (09:53:38 CET)
Breast cancer is the most commonly diagnosed cancer in women worldwide. Approximately, 70 % of breast cancer patients express hormone receptors (HR) (Luminal subtype). Adjuvant endocrine treatments are the standard of care in HR+/HER2- breast cancer. Over time, about 50% of those patients develop endocrine resistance and metastatic breast cancer. Cyclin-dependent kinase inhibitors (CDKi) in combination with an aromatase inhibitor or fulvestrant have demonstrated superior efficacy increasing progression-free survival, with a safe toxicity profile, in HR+/HER2- metastatic breast cancer patients. CDKi blocks kinases 4/6 ATP-binding domain preventing G1/S cell cycle transition. Despite this, not all patients respond to CDKi and those who respond, finally develop resistance to combination therapy. Different studies, in tumour tissue or cell lines, have tried to elucidate the mechanisms underlying this progression, but there are still no conclusive data. In the last few years, liquid biopsy has contributed relevant information to this knowledge. Liquid biopsy can be performed in real-time, non-invasively and be repeated whenever needed. Circulating tumour material are potential prognostic markers in metastatic luminal breast cancer to determine patient prognosis, monitor disease and treatment selection. The objective of this review is to outline the different studies carried out in HR+ metastatic breast cancer patients treated with CDKi plus endocrine therapy using liquid biopsy approaches looking for possible resistance mechanisms.
REVIEW | doi:10.20944/preprints202211.0169.v1
Subject: Life Sciences, Virology Keywords: viroid; resistance; tolerance; RNA silencing; plant hormone; spray-induced gene silencing; genome editing
Online: 9 November 2022 (03:10:00 CET)
Viroids are known the smallest plant pathogens, and although their genome sequences do not encode proteins, they can cause disease in economically important crops. In order to control viroid diseases and mitigate their damage, genetic resources used for breeding of the viroid-resistant crop have been searched, but the practical resistant trait has not been found in almost all viroid-crop combinations, as well as the tolerant trait. Due to the difficulty in exploiting naturally occurring resistance or tolerance, various effective strategies have been devised to control viroid diseases using non-transforming or transforming techniques. Meanwhile, extensive findings related to viroid resistance and tolerance may lead to confer resistance or tolerance to viroid infection by combining with the recently emerged new technologies (e.g., spray-induced gene silencing and genome-editing technologies), which are believed to be more environmentally viable and acceptable to the general public than previously reported approaches. In particular, some genome-modified crops produced by the latter technology are already on the market. In this review, we comprehensively summarize the current status about investigation of naturally occurring genetic traits for viroid resistance and tolerance, accumulating knowledge about host factors involved in viroid pathogenicity, and various basic technologies developed to try to possible viroid disease control strategies. Furthermore, we discuss prospects and challenges for the achievement of more effective, practical, and sustainable disease control of viroid.
ARTICLE | doi:10.20944/preprints202004.0231.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: schizophrenia; neuroimmunomodulation; inflammation; biomarkers; major depression; treatment resistance
Online: 15 April 2020 (08:19:08 CEST)
Objective: About a third of schizophrenia patients are treatment-resistant to antipsychotic therapy. No studies established the fingerprints or pathway-phenotypes of treatment-resistant schizophrenia. The present study aimed to delineate the pathway-phenotypes of non-responders (NRTT) and partial responders (PRTT) to treatment using machine learning. Methods: We recruited 115 schizophrenia patients and 43 healthy controls and measured schizophrenia symptom dimensions, neurocognitive tests, plasma CCL11, interleukin-(IL)-6, IL-10, Dickkopf protein 1 (DKK1), high mobility group box-1 protein (HMGB1), κ- and µ-opioid receptors (KOR and MOR, respectively), endomorphin-2 (EM-2), and β-endorphin. Results: Machine learning showed that the NRTT group is a qualitatively distinct class and is significantly discriminated from PRTT with an accuracy of 100% using a neuro-immune-opioid-cognitive (NIOC) pathway-phenotype with as main determinants list learning, controlled word association, and Tower of London test scores, CCL11, IL-6, and EM2. The top-5 symptom domains separating NRTT from PRTT were in descending order: psychomotor retardation, negative symptoms, psychosis, depression, and mannerism. Moreover, a NIOC pathway also discriminated PRTT from healthy controls with an accuracy of 100% while all PRTT and controls were authenticated as belonging to their respective classes. Conclusion: A non-response to treatment with antipsychotics is determined by increased severity of specific symptom profiles coupled with deficits in executive functions, and episodic and semantic memory, and aberrations in neuro-immune and opioid pathways. No patients showed complete remission after treatment indicating that non-remitting in PRTT is attributable to increased HMGB1 and residual deficits in attention, executive functions, and semantic memory.
REVIEW | doi:10.20944/preprints202104.0733.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Topoisomerase I; irinotecan; camptothecin; ubiquitination; proteasomal degradation; drug resistance
Online: 28 April 2021 (08:44:34 CEST)
Abstract: Targeted ubiquitination and proteasomal degradation regulates various cellular pathways, and the discovery that CPT induced rapid proteasomal degradation of topoI is the primary mechanism of CPT resistance was novel and compelling. CPTs are used extensively to treat various solid tumors like colorectal, gastric, pancreatic, ovarian and small cell lung cancer. The response rate is low and the classical mechanisms of drug resistance are yet to be validated. Remarkably, CPT resistant cells degrade topoI rapidly by UPP and recently we’ve published the molecular determinants of this pathway. To further understand the UPP mediated CPT resistance mechanism we used targeted proteasome prohibition by ixazomib (MLN9708) to stabilize topoI and determine its impact on CPT resistance. CPT resistant and sensitive cancer lines were both treated with ixazomib in combination with CPT. The CPT induced rate of topoI degradation, and its stabilization by ixazomib, was visualized and estimated by immunohistochemistry, immunofluorescence and immunoblotting assays, MTT and subG1 assays provided the drug sensitivity. Our results demonstrate that cells that degrade topoI rapidly are very resistant to CPT, and ixazomib significantly inhibits CPT induced topoI degradation. Notably, inhibition of proteasomal degradation by ixazomib overcomes the drug resistance and sensitizes the cells for CPTs.
ARTICLE | doi:10.20944/preprints202001.0255.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: Cordycepin; Cisplatin-resistance; Resensitization; MDR1; Ets-1; AKT
Online: 22 January 2020 (09:18:20 CET)
Resistance of tumor cells to anticancer drugs is a major obstacle in tumor therapy. In this study, we investigated the mechanism of cordycepin-mediated resensitization to cisplatin inT24R2, a derived T24 cell line. Treatment with cordycepin or cisplatin (2 g/ml) alone could not induce cell death of T24R2, but combination treatment of these drugs significantly induced apoptosis of the cells through mitochondrial pathway including depolarization of mitochondrial membrane, decrease of anti-apoptotic proteins, Bcl-2, Bcl-xL, and Mcl-1, and increase of pro-apoptotic proteins, Bak and Bax. . High expression of MDR1 was the cause of cisplatin resistance in T24R2, and cordycepin significantly reduced MDR1 expression through inhibition of MDR1 promoter activity. MDR1 promoter activity was dependent on a transcription factor, Ets-1, in T24R2 cells. Although there is a correlation between MDR1 and Ets-1 expression in bladder cancer patients, active Ets-1, Thr-38 phosphorylated form (pThr-38), was critical to induce MDR1 expression. Cordycepin decreased pThr-38 Ets-1 level through inhibition of AKT, which reduced MDR1 transcription and induced the resensitization of T24R2 to cisplatin. The results suggest that cordycepin effectively resensitizes cisplatin-resistant bladder cancer cells to cisplatin, thus serving as a potential strategy for treatment of anti-cancer drug resistant patients.
ARTICLE | doi:10.20944/preprints202111.0341.v1
Subject: Engineering, Civil Engineering Keywords: resistance; bending; axial force; reinforced concrete; composite; section models
Online: 19 November 2021 (08:26:27 CET)
The paper presents section models for analysis of the resistance of RC members subjected to bending moment with or without axial force. To determine the section resistance the nonlinear stress-strain relationship for concrete in compression is assumed, taking into account the concrete softening. It adequately describes the behavior of RC members up to failure. For the reinforcing steel linear elastic-ideal plastic model is applied. For the ring cross-section subjected to bending with axial force the normalized resistances are derived in the analytical form by integrating the cross-sectional equilibrium equations. They are presented in the form of interaction diagrams and compared with the results obtained by testing conducted on RC columns under eccentric compression. Furthermore, the ultimate normalized bending moment has been derived for the rectangular cross-section subjected to bending without axial force. It was applied in the cross-sectional analysis of steel and concrete composite beams, named BH beams, consisting of the RC rectangular core placed inside a reversed TT welded profile. The comparisons made indicated good agreements between the proposed section models and experimental results.
Subject: Biology, Anatomy & Morphology Keywords: winter wheat; mycotoxins; Fusarium; resistance; ergosterol; trichothecenes; zearalenone
Online: 17 May 2021 (09:56:21 CEST)
Fusarium head blight (FHB) can cause contamination of cereal grain with mycotoxins. Winter wheat is also infected with FHB. It is more resistant than durum wheat to head infection and less than other small grain cereals. The aim of this study was to identify winter wheat lines that combine low head infection and kernel damage with low toxin contamination. Resistance to FHB of 27 winter wheat lines and cultivars was evaluated over a three-year experiment established in two locations. At the anthesis stage, heads were inoculated with Fusarium culmorum isolates. The FHB index was scored and the percentage of Fusarium-damaged kernels (FDKs) assessed. The grain was analysed for type B trichothecenes (deoxynivalenol and derivatives, nivalenol) and zearalenone content. The average FHB index was 12.9%. The proportion of FDK was 6.9% (weight) and 8.5% (number). An average content of deoxynivalenol amounted to 3.543 mg/kg and nivalenol to 2.115 mg/kg. In total, it was 5.804 m/kg of type B trichothecenes. The zearalenone content in the grain was 0.214 mg/kg. Relationships between FHB index, FDK and mycotoxin contents were highly significant for wheat lines; however, they were stronger for FDK versus mycotoxins. Breeding lines combing all types of FHB resistance were found, and five of them had resistance similar to that of wheat lines with the Fhb1 gene.
ARTICLE | doi:10.20944/preprints202211.0144.v1
Subject: Life Sciences, Microbiology Keywords: Urinary tract infection; Ghana; Antimicrobial resistance (AMR); Multi-drug resistance (MDR); MDS Lancet Laboratories; AWaRE classification; Uropathogens
Online: 8 November 2022 (03:25:41 CET)
Management of urinary tract infection is challenged by increasing antimicrobial re-sistance (AMR) worldwide. In this study we describe the trends in antimicrobial re-sistance of uropathogens isolated from the largest private sector laboratory in Ghana over a five-year period. We reviewed positive urine cultures at the MDS Lancet Laboratories from 2017 to 2021. Proportions of uropathogens with antimicrobial resistance to oral and parenteral antimicrobials recommended by the Ghana standard treatment guidelines were determined. The proportion of multi-drug resistant isolates, ESBL and car-bapenemase-producing phenotypes were determined. Of 94,134 urine specimens submitted for culture, 20,010 (22.1%) were culture positive. Enterobacterales were the commonest group of organisms, E. coli (70.6) being the commonest isolate and Enterococcus spp. the commonest gram positive (1.3%) organisms. Among oral antimicrobials the highest resistance was observed to ciprofloxacin (62.3%) and cefuroxime (60.2) %) and the least resistance to Fosfomycin (1.9%). The least resistance among parenteral antimicrobials was to meropenem ( 0.3%). Highest multi-drug resistance levels were observed among Klebsiella spp. (68.6%) and E. coli (64.0%). ESBL positivity was highest in Klebsiella spp. (58.6%) and E. coli (50.0%). There may be a need to review the Ghana standard treatment guidelines to reflect increased resistance among uropathogens to recom-mended antimicrobials
ARTICLE | doi:10.20944/preprints201909.0247.v2
Subject: Keywords: obesity; obesity paradox; diabetes; insulin resistance (IR); whole body insulin resistance (WBIR); tissue-specific insulin resistance; muscle insulin resistance (MIR); subcutaneous insulin resistance (s-AIR); visceral adipose insulin resistance (v-AIR); hepatic insulin resistance (HIR); lipid-induced insulin resistance (LIIIR); glycation-induced insulin resistance (GIIIR)
Online: 9 October 2019 (04:21:56 CEST)
Even though it has long been known that diabetes develops in distinctive stages over a long span of time, no comprehensive diabetes development model has been developed yet. Insulin resistance (IR) plays a central role in development of diabetes. A widespread belief regarding IR is that it is a global parameter affecting the whole body simultaneously by impairing merely glucose uptake in tissues. However, the analysis by a new methodology that we have named integrated approach suggests that IR not merely impairs glucose uptake in tissues but also produces tissue-specific metabolic disruptions varying widely from tissue to tissue, and that IR would not necessarily develop simultaneously over the whole body but instead develop first preferentially in the muscle tissue with a relatively low cell turnover and then progress in sequence to the subcutaneous adipose tissue to the visceral adipose tissue to the liver with higher cell turnovers. This is the most important rationale for subdividing IR into four distinct tissue-specific IRs: muscle insulin resistance (MIR), subcutaneous adipose insulin resistance (s-AIR), visceral adipose insulin resistance (v-AIR), and hepatic insulin resistance (HIR). Sequential development of tissue-specific IRs, in the order of MIR, s-AIR, v-AIR, and HIR, producing tissue-specific metabolic disruptions, is nothing but the whole body insulin resistance (WBIR) evolving in four distinctively insulin-resistant stages. Four-stage evolution from rapid weight gain to visceral obesity to rapid weight loss to full-blown diabetic state not only complies well with the natural development history of diabetes, but also resolves most of controversies on diabetes or obesity. Development of the four-stage WBIR evolution model, which also refutes the entrenched notion of the lipid-induced insulin resistance (LIIR) but instead supports the glycation-induced insulin resistance (GIIR) proposed in this study, may possibly be considered a breakthrough in study of diabetes as well as obesity.
REVIEW | doi:10.20944/preprints202202.0200.v1
Subject: Life Sciences, Microbiology Keywords: antibiotic resistance genes; antibiotic resistance gene database; annotation of antibiotic resistance genes
Online: 17 February 2022 (04:52:10 CET)
As the prevalence of antimicrobial resistance genes is increasing in microbes, we are facing the return of the preantibiotic era. Consecutively, the number of studies concerning antibiotic resistance and its spread in the environment is rapidly growing. Next generation sequencing technologies are widespread used in many areas of biological research and antibiotic resistance is no exception. For the rapid annotation of whole genome sequencing and metagenomic results considering antibiotic resistance, several tools and data resources were developed. These databases, however can differ fundamentally in the number and type of genes and resistance determinants they comprise. Furthermore, the annotation structure and metadata stored in these resources can also contribute to their differences. Several previous reviews were published on the tools and databases of resistance gene annotation, however, to our knowledge, no previous review focused solely and in depth on the differences in the databases. In this review, we compare the most well-known and widely used antibiotic resistance gene databases based on their structure and content. We believe that this knowledge is fundamental for selecting the most appropriate database for a research question and for the development of new tools and resources of resistance gene annotation.
ARTICLE | doi:10.20944/preprints202212.0449.v1
Subject: Life Sciences, Microbiology Keywords: redox system; cryptococcal meningitis; oxidative stress; ergosterol; resistance
Online: 23 December 2022 (07:56:36 CET)
Cryptococcus neoformans threaten the health, causing cryptococcal meningitis and pneumonia, especially in immunosuppressed patients, which can be fatal. Recently, our research group evaluated and studied the mechanisms of action of four synthetic peptides (SP) against C. neoformans. Here, in silico and in vitro analyses help deepen understanding of peptides' mechanisms of action. The interaction of the peptides with a membrane receptor was analyzed by docking analysis, in addition to ROS overproduction and the modulation of redox metabolism, inhibition of ergosterol biosynthesis, and release of cytochrome c. Out of four, three peptides interacted with membrane receptor PHO36 altering its structure and function and leading to a higher accumulation of O₂- and H2O2. C. neoformans cells treated with SP presented a reduction in the activity of antioxidant enzymes, corroborating ROS accumulation. However, in the presence of the antioxidant ascorbic acid, some peptides could not induce this oxidative stress and have the activity against C. neoformans affected. Curiously, two of these SPs still maintained the activity against C. neoformans and even induced the membrane pore formation as revealed by propidium iodide uptake assay, revealing their mechanism of action is ROS-independent. Additionally, SPs inhibited the biosynthesis of ergosterol, which corroborates the pore formation on the membrane of C. neoformans cells, inhibited the lactate dehydrogenase activity affecting the cell metabolism, and induced the release of Cyt c from the mitochondria inducing death by apoptosis in the cryptococcal cells. Our findings strongly suggest that SPs act by multiple mechanisms, making it difficult for C. neoformans to acquire resistance highlighting the potential of SPs as alternative molecules in treating infections caused by C. neoformans.
REVIEW | doi:10.20944/preprints202002.0309.v1
Subject: Life Sciences, Microbiology Keywords: antimicrobial resistance; foodborne illness; food safety; food security; sustainable development
Online: 23 February 2020 (02:21:34 CET)
Antimicrobial resistance (AMR) threatens to reverse the essential benefits of antibiotics not only in humans, where decades of advancements in healthcare outcomes are endangered but also in the food production industry. The emergence of AMR in the pre- and post-harvest systems presents a serious risk of contamination or infection directly by antibiotic-resistant bacteria (ARB) and genes (ARGs) for farmers, agricultural practitioners, abattoir workers, food handlers and their associated contacts as well as consumers at the end of the food chain. Any breach in the food safety barrier leading to the emergence and spread of ARB and ARGs has severe multi-sectorial implications and threatens to reverse decades of human and animal health improvements globally. As the world moves towards Sustainable Development Goals (SDGs), food safety is a critical element to improve and strengthen global health, security and ensure sustainable development. This paper presents the challenge of AMR through the lens of food safety, by highlighting its multi-sectoral and multi-dimensional implications not only the SDG on food safety but also on food security, public health, animal health and welfare, the environment and climate and socio-economic development.
ARTICLE | doi:10.20944/preprints202208.0378.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Antibiotic resistance; Colonization; Prevalence; GBS; Resistance phenotype
Online: 22 August 2022 (08:04:16 CEST)
Group B Streptococcus (GBS), a commensal in the body, causes a wide range of infectious diseases. The colonisation levels of GBS and its resistance profile to antibiotics provide important information useful for orienting prevention strategies. There is little data available on the subject with determination of resistance phenotypes in Cameroon. We therefore aimed to determine the prevalence of colonization, antibiotic resistance, including patterns of inducible resistance to clindamycin of GBS in Yaounde. To achieve this goal, a prospective cross-sectional study with an analytical component was carried out from the 28th June to the 29th August 2020 at the BIOSANTE laboratory and the Yaounde Gynaeco-Obstetrics and Paediatrics hospital. Vaginal swabs and urine were collected on 163 women. This samples were analysed using 5% defibrinated sheep blood agar and chocolate plus polyvitex agar. The isolates were identified using the morphology of the colony, Gram staining, haemolysis, catalase test and latex grouping test. Antibiotic susceptibility testing was done by disk diffusion method following the recommendations of the ACFSM 2019. The double disk diffusion method was used to identify isolates with clindamycin inducible resistance. Our data was analysed by the software SPSS version 2.1. The results obtained showed that the global prevalence of colonization by GBS was 37% (57/163), 40.35% in non-pregnant women and 59.65% in pregnant women. Pregnancy (P-value = 0.019) and gestational age (P-value = 0.025) constituted the risk factors of maternal colonization by GBS. In addition, the strains of GBS were resistant to all antibiotics tested. A D test showcased that 64.7% of GBS were resistant in a constitutive manner to clindamycin. We also note the presence of M phenotypes. As a whole, our results demonstrate that the rate of GBS colonization in this study was similar or higher than those in the previous report in Cameroon. All this indicates that attention should be paid to this bacterium in the monitoring of antimicrobial resistance and in the care of pregnant women and newborns.
ARTICLE | doi:10.20944/preprints202103.0522.v1
Subject: Biology, Anatomy & Morphology Keywords: Commensal bacteria; Neisseria; antimicrobial resistance; multidrug resistance
Online: 22 March 2021 (11:37:13 CET)
Pathogenic Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea. N. gonorrhoeae has evolved high levels of antimicrobial resistance (AR) leading to therapeutic failures even in dual-therapy treatment with azithromycin and ceftriaxone. AR mechanisms can be acquired by genetic transfer from closely related species, such as naturally-competent commensal Neisseria species. At present, little is known about the antimicrobial resistance profiles of commensal Neisseria. Here, we characterized the phenotypic resistance profile of four commensal Neisseria species (N. lactamica, N. cinerea, N. mucosa, and N. elongata) against 10 commonly used antibiotics, and compared their profiles to 4 N. gonorrhoeae strains, using disk diffusion and minimal inhibitory concentration assays. Overall, we observed that 3 of the 4 commensals were more resistant to several antibiotics than pathogenic N. gonorrhoeae strains. Next, we compared the penicillin-binding-protein 2 (PBP2) sequences between commensal and N. gonorrhoeae strains. We found mutations in PBP2 known to confer resistance in N. gonorrhoeae also present in commensal Neisseria sequences. Our results suggest that commensal Neisseria have unexplored antibiotic resistance gene pools that may be exchanged with pathogenic N. gonorrhoeae, possibly impairing drug development and clinical treatment.
ARTICLE | doi:10.20944/preprints202211.0507.v1
Subject: Engineering, Civil Engineering Keywords: cementitious materials; concrete; mortar; freeze-thaw resistance; durability; 3D-scan; Python
Online: 28 November 2022 (09:09:08 CET)
Deterioration of concrete subjected to freezing and thawing climatic conditions is one of most important factors affecting the durability of concrete infrastructure in cold climates. The freeze-thaw resistance of cementitious materials like concrete and mortar can be determined by the CDF test (Capillary Suction of De-icing chemicals and Freeze-Thaw Test). Here, concrete specimens are subjected to repeated freeze-thaw cycles with simultaneous addition of de-icing salt and the amount of material weathered near the surface is determined. For concretes with adequate freeze-thaw resistance, this test method works very well. However, specimens with inadequate or unknown performance often experience increased edge weathering, which is caused by the detachment of the lateral isolation tape. The increasing edge influence thus leads to a falsification of the results and consequently to an underestimation of the actual freeze-thaw resistance of the material. In materials research in particular, however, concretes with high levels of weathering are studied in order to be able to investigate various factors of influence on the freeze-thaw resistance of concretes in a targeted manner. This paper presents a novel methodology that delivers new information regarding the weathering of CDF test samples and the associated distribution function of the height decrease using high resolution 3D scan data. The results indicate a correlation between the progression of the distribution function and the sample's maximum aggregate size. The change of the sample volume can be used to support the weathering results of the standard CDF methodology. The increase of the surface area is used to estimate the tortuosity of the sample surface. It indicates an asymptotic curve approaching a specific maximum value, which is dependent on the the weathering depth of the sample.
ARTICLE | doi:10.20944/preprints201807.0065.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: hypothalamus; insulin resistance; inflammation; docosahexaenoic acid; PI3K inhibitor; AKT
Online: 4 July 2018 (09:58:03 CEST)
Saturated fatty acids are implicated in the development of metabolic diseases, including obesity and type 2 diabetes. There is evidence, however, that polyunsaturated fatty acids can counteract the pathogenic effects of saturated fatty acids. To gain insight into the early molecular mechanisms by which fatty acids influence hypothalamic inflammation and insulin resistance, we performed time-course experiments in a hypothalamic cell line, using different durations of treatment with the saturated fatty acid palmitate, and the omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA). Western blot analysis revealed that palmitate elevated the protein levels of phospho(p)AKT in a time-dependent manner. This effect seems involved in the pathogenicity of palmitate, as temporary inhibition of the PI3K/AKT pathway by selective PI3K inhibitors prevented palmitate-induced insulin resistance. Similarly to palmitate, DHA also increased levels of pAKT, but to a weaker extent. Co-administration of DHA with palmitate decreased pAKT close to the basal level after 8 h, and prevented palmitate-induced insulin resistance after 12 h. Measurement of the inflammatory markers pJNK and pNFκB-p65 revealed tonic elevation of both markers in the presence of palmitate alone. DHA alone transiently induced elevation of pJNK, returning to basal levels by 12 h treatment. Co-administration of DHA with palmitate prevented palmitate-induced inflammation after 12 h, but not at earlier time points.
ARTICLE | doi:10.20944/preprints202101.0040.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Antibiotics; antibiotic resistance; rational drug use; community pharmacist
Online: 4 January 2021 (12:58:43 CET)
Antibiotic resistance (ABR) is an emerging global threat to public health. Substantial evidence has indicated that community pharmacists (CPs) can play a critical role in managing the ever-increasing threat of antibiotic resistance. The study aimed to determine the knowledge, attitude, and practices of CPs (n=180) towards antibiotics and antibiotic resistance as well as to improve the rational use of antibiotics. Two phases of mixed methods (quantitative and qualitative) online study were conducted in Pakistan from August 2019 to March 2020 by using validated questionnaires and semi-structured interview data. Different statistical methods were used to tabulate the quantitative data whereas inductive thematic analysis was conducted to categorize themes from the qualitative data and draw conclusions. Approximately 64.4% were male (mean: 29-33 years old). Overall, CPs had good knowledge of and were familiar with superbugs and their roles in ABR (65.6%, Median=1, IQR=1) although they were poor in differentiating some antibiotic groups with their respective ABR patterns (31.1%, Median=1, IQR=1). Most CPs have a positive attitude towards antibiotics with most (90.0%) having identified ABR as a critical issue in public health (Median=1, IQR=0). Overall, CPs' practices towards antibiotics were reasonable where they tend to educate patients about the rational use of antibiotics (52.8%, Median=1, IQR=1). Two main themes (antibiotics and counseling of patients) were related to self-medication with while educational interventions are the sub-theme. ABR is multifactorial where the subthemes related to budget, time constraints incompetent staff, the absence of CPs, the lack of training, enforcement of laws and regulations are the need of the hour in Pakistan. Effective antibiotic stewardship programs, patient education, and awareness campaigns about antibiotics and ABR along with training of the CPs are important factors that have to be addressed in a timely manner.
ARTICLE | doi:10.20944/preprints201911.0128.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: ditches; grain yield; lodging resistance; root traits; wet-seeded rice
Online: 12 November 2019 (10:25:04 CET)
The mechanical hill wet-seeded rice machine is benefits to establish uniform seedling, and ditches were established by using this machine. However, little knowledge is known on the effect of the establishment of ditches on growth, lodging and yield, and their relationship with root traits. In this study, two field experiments were conducted during 2012 and 2013 with using two super rice varieties (i.e. hybrid rice ‘Peizataifeng’ and inbred rice ‘Yuxiangyouzhan’) grown under three ditches establishment treatments (i.e. T1: both water ditches and seed ditches were established by the machine, T2: seed ditches were established by the machine, T3: neither water nor seed ditches were established by the machine). The lodging index and lodging resistance traits, the grain yield and above-ground dry weight and the root traits were measured. The results showed that the lodging index was significantly affected by the treatments with ditches. The strongest lodging resistance was detected in mechanical hill wet-seeded rice with ditches treatment in both 2012 and 2013. The lodging resistance was strongly related to the breaking resistance, the root volume and root superficial area at the heading stage and maturity stage and the total root length at the heading stage. No significant difference was investigated in grain yield or dry weight of mechanical hill wet-seeded rice. Yuxiangyouzhan showed higher grain yield, dry weight and better lodging resistance but unfavorable root growth attributes than Peizataifeng. Therefore, the mechanical hill wet-seeded rice with ditches treatment increased rice lodging resistance is related to root traits.
ARTICLE | doi:10.20944/preprints202009.0473.v1
Subject: Life Sciences, Molecular Biology Keywords: antioxidant enzymes; DNA methylation; epigenetics; plant resistance; root-knot nematodes; ROS; tomato
Online: 20 September 2020 (14:35:29 CEST)
Two wild-type field populations of root-knot nematodes (Mi-Vfield, Mj-TunC2field), and two isolates selected for virulence in laboratory on resistant tomato cultivars (SM2V, SM11C2), were used to induce a resistance reaction in tomato to the soil-borne parasites. Epigenetic and metabolic mechanisms of resistance were detected and compared with those occurring in partially or fully successful infections. The activated epigenetic mechanisms in plant resistance, as opposed to those activated in infected plants, were detected by analysing the methylated status of total DNA, by ELISA methods, and the expression level of key genes involved in the methylation pathway, by qRT-PCR. DNA hypo-methylation and down-regulation of two methyl-transferase genes (CMT2, DRM5), characterized the only true resistant reaction obtained by inoculating the Mi-1.2-carrying resistant tomato cv Rossol with the avirulent field population Mi-Vfield. On the contrary, in the roots into which nematodes were allowed to develop and reproduce, total DNA was generally found to be hyper-methylated and methyl-transferase genes up-loaded. DNA hypo-methylation was considered to be the upstream mechanism that triggers the general gene over-expression observed in plant resistance. Gene silencing induced by nematodes may be obtained through DNA hyper-methylation and methyl-transferase gene activation. Plant resistance is also characterized by an inhibition of the anti-oxidant enzyme system and activation of the defence enzyme chitinase, as opposed to the activation of such a system and inhibition of the defence enzyme glucanase in roots infested by nematodes.
ARTICLE | doi:10.20944/preprints201808.0305.v1
Subject: Life Sciences, Microbiology Keywords: Ostreococcus tauri; Mamiellophyceae; Phycodnaviridae; resistance; karyotype; rearrangement; chromosome; specificity; host range; adsorption
Online: 17 August 2018 (12:26:51 CEST)
Prasinoviruses are large dsDNA viruses commonly found in aquatic systems worldwide, where they can infect and lyse unicellular prasinophyte algae such as Ostreococcus. Host susceptibility is virus strain-specific, but resistance of susceptible Ostreococcus tauri strains to a virulent virus arises frequently. In clonal resistant lines that re-grow, viruses are usually present for many generations, and genes clustered on chromosome 19 show physical rearrangements and differential expression. Here, we investigated changes occurring during the first two weeks after inoculation of viruses. By serial dilutions of cultures at the time of inoculation, we estimated the frequency of resistant cells arising in virus-challenged O. tauri cultures to be 10−3–10−4 of the inoculated population. Re-growing resistant cells were detectable by flow cytometry 3 days post-inoculation (dpi), visible re-greening of cultures occurred by 6 dpi, and karyotypic changes were visually detectable at 8 dpi. Resistant cell lines showed a modified spectrum of host-virus specificities and much lower levels of OtV5 adsorption.
REVIEW | doi:10.20944/preprints202009.0748.v1
Subject: Biology, Anatomy & Morphology Keywords: Verticillium dahliae; plant-pathogen interactions; disease resistance; integrated disease management
Online: 30 September 2020 (14:10:04 CEST)
Tomato (Solanum lycopersicum L.) is a valuable horticultural crop grown and consumed worldwide. Optimum production is hindered by several factors of which Verticillium dahliae, the cause of Verticillium wilt, is one of the major biological constraints in temperate production regions. V. dahliae is difficult to manage because it is a vascular pathogen, has a broad host range and worldwide distribution, and can persist in soil for years. Understanding the pathogen virulence and genetic diversity, host resistance, and plant-pathogen interactions can ultimately inform the development of integrated strategies to manage the disease. In recent years, considerable research has focused on providing new insight into these processes as well as the development and integration of environment-friendly management approaches. In this review, we discuss and summarize the recent findings on the race and population structure of V. dahliae; pathogenicity factors; host genes, proteins, and enzymes involved in defense; the emergent management strategies, and recent approaches to managing Verticillium wilt in tomatoes.
Subject: Keywords: water saving; resistance to change; perceived risk; intentions; Sustainable Development Goal 12
Online: 19 April 2021 (14:25:22 CEST)
Both academic literature and global organizations have emphasized the need for responsible water consumption, as stated in the Sustainable Development Goal 12. However, individuals’ water-saving behaviors in their current state are not enough. This situation entails a resistance to change (RC) in consumer habits and a lack of perceived risk of scarcity. The novelty of this study lies in examining the influence of RC (through its emotional, cognitive, and confidence components) and perceived risk on water-saving intention. Interviews (n = 384) were conducted in the southeast Mediterranean area of Spain by interviewers using a paper-and-pencil questionnaire. The results of the structural equation modeling show that the perceived risk and the components of cognitive rigidity and negative emotions exert a direct influence on water-saving habits and an indirect influence on water-saving intention. None of the components of RC directly influence intention, and a lack of confidence in the outcomes of water saving does not influence water-saving habits or water-saving intention. In addition to the results obtained, the novelty of the work lies in the idea that in order to influence the perception of the risk of water scarcity through awareness campaigns, it is better to use an emotional message rather than showing facts or information, because this does not drive water saving behavior.
ARTICLE | doi:10.20944/preprints202102.0373.v1
Subject: Life Sciences, Biochemistry Keywords: ostracod; biomimetics; transparency; scatch resistance; impact resistance; armory
Online: 17 February 2021 (10:27:26 CET)
In this study we mimic the unique, transparent protective carapace (shell) of myodocopid ostracods, through which their compound eyes see, to demonstrate that the carapace ultrastructure also provides functions of strength and protection for a relatively thin structure. The bulk ultrastructure of the transparent window in the carapace of the relatively large, pelagic cypridinid (Myodocopida) Macrocypridina castanea was mimicked using thin film deposition of dielectric materials to create a transparent, 15 bi-layer material. This biomimetic material was subjected to the natural forces withstood by the ostracod carapace in situ, including scratching by captured prey and strikes by water-borne particles. The biomimetic material was then tested in terms of its extrinsic (hardness value) and intrinsic (elastic modulus) response to indentation along with its scratch resistance. The performance of the biomimetic material was compared with that of a commonly used, anti-scratch resistant lens and polycarbonate that is typically used in the field of transparent armoury. The biomimetic material showed the best scratch resistant performance, and significantly greater hardness and elastic modulus values. The ability of biomimetic material to revert back to its original form (post loading), along with its scratch resistant qualities, offers potential for a biomimetic eye protection coating that could enhance material currently in use.
ARTICLE | doi:10.20944/preprints201807.0103.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: Corrosion Resistance; TIG; Hardness; Wear Resistance; SS 304
Online: 5 July 2018 (16:30:30 CEST)
The aim of this work is evaluation of corrosion behavior of SS 304 coated through TIG process. In this work, Ti tube cored with graphite powder was applied. Experimental processes were shown that the optimum parameters for coating procedure are voltage of 15V, current density of 120A and the speed of 2.1mm/s. Investigations on corrosion resistance of coating are shown that not only this composite coating can improve the tribological behavior of this type of stainless steel, but also there is an improvement in its deteriorative property. Moreover, it is observed that mass reduction in coating is 5 times lower than the base metal.
ARTICLE | doi:10.20944/preprints202201.0464.v1
Online: 31 January 2022 (13:25:38 CET)
The mosaic disease in maize is caused by Sugarcane mosaic virus (SCMV), a member of the Potyviridae family. The best strategy to cope with viral infections is the use of disease-resistant maize lines. To better understand the resistance response to SCMV, we analyzed differentially expressed genes among a resistant line (CI-RL1), a susceptible line (B73), and the F1 progeny from a cross between both lines using RNA-Seq data. We also analyzed transcript expression pattern clustering to allocate previously reported resistance candidate genes. GO enrichment analysis of biological processes highlighted a strong regulation in ROS detoxification in both the susceptible and resistant lines. The enrichment of cellular components led to the identification of an integral component of the plasma membrane in the RL line. Transcript expression patterns provide evidence of the importance of host translation in virus response, showing the diverse and complex behavior of eIF4E homologs and the presence of eleven eEF1α factors in maize. In addition, we identified two genes putatively implied in long-distance movement: ZmPiezo and ZmPVIP1. Finally, we propose an ABC transporter to be associated with viral resistance.
ARTICLE | doi:10.20944/preprints201910.0103.v1
Subject: Life Sciences, Microbiology Keywords: beta-lactamase; cephalosporin; cefotaxime; transconjugation; plasmid-borne resistance
Online: 9 October 2019 (11:03:44 CEST)
Clinical pathogens especially Gram-negative bacteria developing resistance to third-generation cephalosporins are making the clinical outcome more complicated and serious. This study was undertaken to evaluate the distribution of extended-spectrum beta-lactamases in Tamil Nadu regions in India. For this study, clinical samples were collected from five different hospitals located in Tamil Nadu and ESBL producing Gram-negative isolates were characterized. Minimal inhibitory concentration (MIC) was performed using cefotaxime and ceftazidime. The blaESBL producing genes were screened using multiplex PCR for the genes, CTX-M group-1,-2,-8,-9,-26. Conjugation studies were performed using E. coli AB1157 as a recipient for the isolates harbouring plasmid-borne resistance following broth-mating experiment. In total, 1500 samples were collected and 599 Gram-negative bacteria were isolated that included Escherichia coli (n=233), Klebsiella pneumoniae (n=182), Pseudomonas aeruginosa (n=79), Citrobacter spp. (n=30), Proteus mirabilis (n=28), Salmonella spp. (n=21), Acinetobacter baumannii (n=12), Serratia spp. (n=6), Shigella spp. (n=4), Morganella morganii (n=3) and Providencia spp. (n=1). MIC results showed that 358 isolates were resistant to cefotaxime and ceftazidime. Further, ESBL gene amplification results showed that 19 isolates had CTX-M group-1 gene including E. coli (n=16), K. pneumoniae (n=2) and P. aeruginosa (n=1) whereas one M. morganii isolate had CTX-M group-9 gene in their plasmid. Through conjugation studies, 12/20 isolates were found to be involved in the transformation of its plasmid-borne resistance gene. Our study highlighted the role of horizontal gene transfer in the dissemination of plasmid-borne blaCTX-M resistance genes among ESBL producing isolates.
ARTICLE | doi:10.20944/preprints201803.0070.v1
Subject: Biology, Entomology Keywords: Aedes aegypti; insecticide resistance; pyrethroid; permethrin; VGSC gene
Online: 9 March 2018 (05:27:12 CET)
Aedes aegypti mosquito is a vector that could transmit various pathogens, such as viruses, bacteria, and parasites. Several human diseases transmitted by Ae. aegypti mosquito are dengue fever (DHF), Chikungunya, Yellow Fever and Zika. The occurance of resistance to various insecticides, including pyrethroid, is a current problem faced by various countries. In this research, a WHO bioassay test on Palembang and Jakarta Ae. aegypti was conducted using 0.25% permethrin pyrethroid insecticide. VGSC gene fragments associated with pyrethroid resistance (L982, S989, I1011, L1014, V1016 and F1534) of resistant and sensitive strains were amplified and analyzed. The test showed the presence of resistance in Ae. aegypti isolates from Palembang and Jakarta. From the results of VGSC gene fragment analyses, it was known that there were mutations (S989P and/or V1016G) on isolates from Palembang and (S989P and/or V1016G) on resistant isolates from Jakarta.
ARTICLE | doi:10.20944/preprints202210.0286.v1
Subject: Life Sciences, Genetics Keywords: cytokines; haplotypes; immune response; Leishmania; regulatory mechanisms; resistance; susceptibility
Online: 19 October 2022 (11:30:49 CEST)
Background: The Ibizan Hound is a canine breed native to the Mediterranean region, where leishmaniasis is an endemic zoonosis. Several studies indicate a low prevalence of this disease in dogs, whereas other canine breeds present a high prevalence. However, the molecular underlaying mechanisms yet remains unknown. Methods: In this study, we analyze the haplotypes of genes encode cytokines related to immune response of Leishmania infantum infection in twenty-four Boxer and twenty-four Ibizan hound apparently healthy using CanineHD DNA Analysis BeadChip including 165,480 mapped positions. Results: The results show that several haplotypes of genes encoding Interleukin 6 (IL6) and Interferon gamma (IFNG) are related to Interferon gamma (IFN-γ), and Interleukins (IL) 2 and 18 serum levels. Our results indicate that the regulation of immune response is different in the two canine breeds analyzed and are related to the haplotype compositions of the genes encoding these cytokines. Conclusions: Future studies are needed to elucidate whether these differences and haplotypes are related to different phenotypes in immune response and expression gene regulation to L. infantum infection in dogs.
ARTICLE | doi:10.20944/preprints201904.0161.v2
Subject: Life Sciences, Other Keywords: antimicrobial resistance; horizontal gene transfer; mathematical modelling; epidemiology; microbiology
Online: 6 May 2019 (10:59:05 CEST)
Antimicrobial resistance (AMR) is one of the greatest public health challenges we are currently facing. To develop effective interventions against this, it is essential to understand the processes behind the spread of AMR. These are partly dependent on the dynamics of horizontal transfer of resistance genes between bacteria, which can occur by conjugation (direct contact), transformation (uptake from the environment) or transduction (mediated by bacteriophages). Mathematical modelling is a powerful tool to investigate the dynamics of AMR, however its application to study the horizontal transfer of AMR genes is currently unclear. In this systematic review, we searched for mathematical modelling studies which focused on horizontal transfer of AMR genes. We compared their aims and methods using a list of predetermined criteria, and utilized our results to assess the current state of this research field. Of the 43 studies we identified, most focused on the transfer of single genes by conjugation in Escherichia coli in culture, and its impact on the bacterial evolutionary dynamics. Our findings highlight the existence of an important research gap on the dynamics of transformation and transduction, and the overall public health implications of horizontal transfer of AMR genes. To further develop this field and improve our ability to control AMR, it is essential that we clarify the structural complexity required to study the dynamics of horizontal gene transfer, which will require cooperation between microbiologists and modellers.
REVIEW | doi:10.20944/preprints202209.0457.v2
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Anti-angiogenic; HIF-1 α; Normalization-window; research; hypoxia; resistance; SBRT; Immunotherapy
Online: 7 October 2022 (09:45:53 CEST)
Multiple biological pathways manifest and latent, meant for human survival, become a liability in cancer cure. With an increasing understanding of innumerable complex paths, cancer progression and development of resistance is no surprise. For the three “vasculature-immune-phenotypic” fundamental changes, hypoxia is the maestro orchestrating the whole gamut of changes (through the master manipulator - HIF-1 α), simultaneously transactivating hundreds of pro-angiogenic genes. Such a complex molecular bio-network begs the question, “Is our cancer research caught in such a tangled web that we have lost sight of the Spider?”. Hypoxia is this Spider weaving compensatory webs with every intervention/ obstruction. Anti-angiogenic (AAG) research has been conducted mainly in silos – exploring independent paths. This review conceptualizes a convergence of a multitude of research worldwide to a single theme of normalizing vasculature as a primary baseline for overcoming resistance to AAGs or their combinations.
ARTICLE | doi:10.20944/preprints202101.0046.v1
Subject: Medicine & Pharmacology, Other Keywords: health care, innovation, resistance, staff behavior, employment relationship, strategy, organizational climate
Online: 4 January 2021 (13:25:12 CET)
Frequent employee resistance to innovation is one of the main barriers of change failure in a health care organization and one of the negative stimuli of employment relationships. Identifying the reasons of resistance is a topical issue for every organization, as the speed of change can affect their competitiveness. Consequently, it is helpful not only to know the causes of potential resistance but also to be ready to control any implicit opposition. The organizational climate and the attitude of the staff play an important role in understanding and accepting innovation. Purpose of the study is to develop a model, which would facilitate the choice of an appropriate strategy necessary to enable the health care organization to eliminate or at least to reduce resistance to often essential innovative changes. The article analyses the root causes of resistance and identifies strategies that help to mitigate or eliminate staff resistance for innovation. Use of suggested model can make easier reducing staff resistance to change processes and thus speed up the implementation of innovations. This methodology can be used to eliminate the reasons for staff resistance to change in health care institutions of different countries, but it was tested in Lithuania and achieved good enough results.
ARTICLE | doi:10.20944/preprints202302.0072.v1
Subject: Biology, Animal Sciences & Zoology Keywords: Prophage; Endolysin; Staphylococcus aureus; Methicillin-resistant Staphylococcus aureus; Antibiotic-resistance; Bovine mastitis.
Online: 3 February 2023 (10:35:34 CET)
The increasing prevalence of methicillin-resistant S. aureus (MRSA) in the dairy industry has become a fundamental concern. Endolysins are bacteriophage-derived peptidoglycan hydrolases that induce the rapid lysis of host bacteria. We investigated endolysin candidates with lytic activity against MRSA and evaluated the lytic activity of the endolysin candidate against S. aureus and MRSA. To identify endolysins, we used the following bioinformatic strategy: (1) retrieval of genetic information, (2) annotation, (3) selection of MRSA, (4) selection of endolysin candidates, and (5) evaluation of protein solubility. We then characterized the endolysin candidate under various conditions. Approximately 67% of S. aureus was detected as MRSA and a total of 114 putative endolysins were found. The 114 putative endolysins were divided into three groups based on their combination of conserved domains. Considering the protein solubility, we selected putative endolysins 177 and 117. Putative endolysin 117 was successfully overexpressed and renamed LyJH1892. LyJH1892 lysed approximately 85% of S. aureus. LyJH1892 showed more potent lytic activity against MRSA than normal S. aureus (relative lytic activity > 125%). LyJH1892 showed broad lytic activity against coagulase-negative Staphylococci (CNS). In conclusion, These findings provide a rapid and useful strategy for the development of specific endolysins against antibiotic-resistant bacterial strains.
ARTICLE | doi:10.20944/preprints202108.0160.v1
Subject: Biology, Entomology Keywords: Pyrethroid; pyrethroid resistance; insecticide resistance; insecticide resistance management; vector control; malaria; malaria control; mosquito; Anopheles
Online: 6 August 2021 (11:19:25 CEST)
Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays was conducted to answer these questions. Evidence suggests that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work would be needed to examine how this may apply to insecticide resistance management.
ARTICLE | doi:10.20944/preprints202205.0021.v1
Subject: Life Sciences, Biochemistry Keywords: Anopheles gambiae; Cameroon; Malaria; Pyrethroids; Resistance Escalation; Cytochrome P450s
Online: 5 May 2022 (05:07:43 CEST)
(1) Background: Malaria remains a global public health problem. Unfortunately, the resistance of malaria vectors to insecticides commonly used threatens disease control and elimination efforts. Molecular mechanisms helping some malaria vectors to now survive to greater doses of insecticides remains poorly understood. Here, we elucidated the pattern of resistance escalation in the main malaria vector Anopheles gambiae in a pesticide-driven agricultural hotspot in Cameroon and its impact on vector control tools; (2) Methods: Larval stages and indoor blood-fed females (F0) were collected in Mangoum in May and November and forced to lay eggs; the emerging mosquitoes were used for WHO tube, synergist and cone tests. Molecular identification was done using SINE PCR whereas TaqMan-based PCR was used for genotyping of L1014F/S and N1575Y kdr and the G119S-ACE1 resistance markers. Transcription profile of candidate resistance genes was performed using qRT-PCR methods. Characterization of the breeding water and soil from Mangoum was also performed using HPLC technique; (3) Results: An. gambiae s.s. was the only species in Mangoum with 4.10 % infection with Plasmodium. These mosquitoes were resistant to all the four classes of insecticides with mortality rates <7% for pyrethroids and DDT and <54% for carbamates and organophophates. This population also exhibited high resistance intensity to pyrethroids (permethrin, alpha-cypermethrin and deltamethrin) after exposure to 5X and 10X discriminating doses and Synergist assays with PBO revealed only a partial recovery of susceptibility to permethrin, alpha-cypermethrin and deltamethrin. Only PBO-based nets (Olyset plus and permaNet 3.0) and Royal Guard showed an optimal efficacy. A high amount of alpha-cypermethrin was detected in breeding sites (5.16 fold LOD) suggesting ongoing selection from agricultural pesticides. The 1014F-kdr allele was fixed (100%) whereas the 1575Y-kdr (37.5%) and the 119S Ace-1R (51.1%) are moderately present. Elevated expression of P450s respectively in permethrin and deltamethrin resistant mosquitoes [CYP6M2 (10 and 34-fold), CYP6Z1(17 and 29-fold), CYP6Z2 (13 and 65-fold), CYP9K1 (13 and 87-fold)] supports their role in the observed resistance besides other mechanisms including chemosensory genes as SAP1 (28 and 13-fold), SAP2 (5 and 5-fold),SAP3 (24 and 8-fold) and cuticular genes as CYP4G16 (6 and 8-fold) and CYP4G17 (5 and 27-fold). However, these candidate genes were not associated with resistance escalation as expression level did not differ significantly between 1x, 5x and 10x surviving mosquitoes. (4) Conclusions: Intensive and multiple resistance is being selected in malaria vectors from pesticide-based agricultural hotspot of Cameroon leading to loss of efficacy of pyrethroid-only nets. Further studies are needed to decipher the molecular basis underlying such resistance escalation to better assess its impact on control interventions.
ARTICLE | doi:10.20944/preprints201911.0077.v1
Subject: Life Sciences, Microbiology Keywords: antibiotics; antibiotics resistance; antimicrobial resistance; dispensing; pharmacist; prescription; Tanzania
Online: 7 November 2019 (15:03:56 CET)
Background: Inappropriate use of antibiotics has been reported to contribute to the emergence and increase of antimicrobial resistance (AMR) in the world. Antibiotics are prescription-only medicines to be dispensed to a person with a legal prescription inscribed by a qualified medical practitioner. Enforcing the dispensing of antibiotics with prescription is a way to promote the rational use of antibiotics and preventing the development and spread of AMR. It is, therefore, the responsibility of a pharmacist to dispense or supervise the dispensing of antibiotics in pharmacies and ensure its rational use. This study aimed to assess pharmacists’ knowledge, attitude and practice regarding the dispensing of antibiotics without prescription in Tanzania. Methods: An online semi-structured questionnaire was designed, tested and shared with licensed pharmacists in Tanzania through an invitation link sent in their official WhatsApp groups. A list of names, contacts and emails of licensed pharmacists obtained from the Pharmacy Council was used to directly contact and request pharmacist to fill the questionnaire, in case the pharmacist contact was not on WhatsApp, a text SMS invitation was sent. Study data were collected and managed using REDCap electronic data capture tools hosted at Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania. Data were then downloaded and exported into Statistical Package for Social Sciences (SPSS) version 20 for data analysis; Chi-square test was used to test association for categorical data, where a p-value of less than 0.05 was considered statistically significant. Results: More than 75% of pharmacists had excellent knowledge about the legal requirements for dispensing antibiotics and of the AMR challenge. Of the interviewed pharmacists, seventy-four percent admitted to dispensing antibiotics without prescription in their daily practice. The main reasons for administering antibiotics without prescription were the profitability nature of pharmacy business, a failure of the patient to get a prescription and lack of stringent regulatory authorities. Penicillins, macrolides and floroquinolones were the classes of antibiotics mostly dispensed without a prescription. Conclusion: The study shows that the dispensing of antibiotics without prescription is a common practice in Tanzania. The regulatory authorities should make regular inspections in pharmacies to detect this malpractice. The community should be trained on the importance of taking laboratory tests before getting medications for their sickness by a qualified medical practitioner.
REVIEW | doi:10.20944/preprints201808.0090.v1
Subject: Life Sciences, Microbiology Keywords: antimicrobial resistance; infection control practices; antibiotic resistance; pathogens; coevolution
Online: 5 August 2018 (10:18:40 CEST)
The antibiotic or antimicrobial resistance is rapidly spreading in microbes relevant to human health. Two visible major contributory factors have been the indiscriminate overuse of antimicrobials for preventing diseases in human and to enhance the productivity in agriculture sector. To mitigate the potential threat posed by post-antibiotic era, the global health stakeholders have been making extra efforts at a war footing to formulate and implement global and national plans of action. In the current article, an endeavour is made to provide a perspective to look beyond the current focus on just use of the antimicrobials. Attention has been drawn towards various obvious and not-so-obvious self-preservation infection-prevention practices in vogue from the pre-antibiotic era whose usage has been on decline in the antibiotic era for various reasons. Particularly, the practices with a clear potential to effectively decrease the spread of pathogens through contact, curtail the evolution and dissemination of the antimicrobial resistance in local environment and its introduction into the global community, should be Identified and strengthened to make them part of comprehensive hygiene and quarantine practices. Broadly, the suggestions pertaining to the personal and community hygiene including bereavement practices, isolation and quarantine of suspected pathogen carriers, and water and environment security have been made to invoke a constructive debate and discussion among various stakeholders for their evaluation and implementation to effectively delay the development of antimicrobial resistance wherever possible and disrupt its spread to pathogens.
COMMUNICATION | doi:10.20944/preprints202111.0052.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: RNA-based NGS; EGFR mutated NSCLC; acquired resistance; RET-fusion; rebiopsy
Online: 2 November 2021 (22:19:36 CET)
The unavoidable progression of EGFR-mutated NSCLC on EGFR-TKIs forces us to discover solutions for further therapies. Herein, we discuss the necessity of accurate genomic mapping of progressive disease illustrated by a patient case. Tumor rebiopsies at progression are strongly needed to characterize acquired resistance to EGFR-TKI. The necessary data, however, may be reliably obtained only by deep targeted next generation sequencing (NGS) of both DNA and RNA. The reported case is a patient with EGFR-mutant NSCLC, who progressed during second line Osimertinib with subsequent targeted treatment determined by the detection of an acquired intergenic ANK3-RET-fusion with concomitant PTEN-mutation and MDM2-amplification. These three acquired gene alterations represent potential mechanisms of TKI-resistance, not previously reported on second line Osimertinib. Yet, while PTEN-mutations and MDM2-amplification are currently undruggable, the ANK3-RET fusion allowed further personalized treatment by combining continuation of Osimertinib with the RET-TKI Pralsetinib, which resulted in objective partial response, so far for 7 months, and significant clinical improvement. Hence, complementary DNA- and RNA-based targeted NGS may be of importance in clinical routine to better reveal the current molecular state of the disease and contribute to the identification of further targeted therapy strategies. Indeed, further cases with acquired RET-fusions, including ANK3-RET, should be investigated to fully determine the effectiveness of RET-TKI-Osimertinib combinations.
REVIEW | doi:10.20944/preprints202010.0629.v1
Subject: Biology, Anatomy & Morphology Keywords: resistance; cultivar; biopesticide; biological control; chemical control; life cycle; CLM
Online: 30 October 2020 (08:52:51 CET)
The coffee leaf miner (CLM) Leucoptera coffeella moth is a major threat to coffee production. Insect damage is related to the feeding behavior of the larvae on the leaf. During the immature life stages, the insect feeds in the mesophyll, triggering necrosis and causing loss of photosynthetic capacity, defoliation, and significant yield loss to coffee crops. Chemical control is mandatory to sustain the coffee production chain, though market requirements move towards conscious consumption, claiming for more sustainable methods. In this overview, we discuss aspects about the CLM concerning biology, history, geographical distribution, economic impacts, and the most relevant control strategies in progress. Insights to develop an integrate approach for a safer and eco-friendly control of the CLM are discussed, including bio-extracts, nanotechnology, pheromones, and tolerant cultivars.
REVIEW | doi:10.20944/preprints202207.0031.v1
Subject: Life Sciences, Biophysics Keywords: Cell-state transitions; Phenotypic plasticity; Cancer Stem Cells; Intratumoral heterogeneity; Lamarckian Induction; Drug resistance
Online: 4 July 2022 (04:56:00 CEST)
Intratumoral heterogeneity can exist along multiple axes: Cancer Stem Cells (CSCs)/non-CSCs, drug-sensitive/drug-tolerant states and a spectrum of epithelial-hybrid-mesenchymal phenotypes. Further, these diverse cell-states can switch reversibly among one another, thereby posing a major challenge to therapeutic efficacy. Therefore, understanding the origins of phenotypic plasticity and heterogeneity remains an active area of investigation. While genomic components (mutations, chromosomal instability) driving heterogeneity have been well-studied, recent reports highlight the role of non-genetic mechanisms in enabling both phenotypic plasticity and heterogeneity. Here, we discuss various processes underlying phenotypic plasticity such as stochastic gene expression, chromatin reprogramming, asymmetric cell division and the presence of multiple “attractors”. These processes can facilitate a dynamically evolving cell population such that a subpopulation of (drug-tolerant) cells can survive lethal drug exposure and recapitulate population heterogeneity on drug withdrawal, leading to relapse. These drug-tolerant cells can be both pre-existing and also induced by the drug itself through cell-state reprogramming. The dynamics of cell-state transitions both in absence and presence of the drug can be quantified through mathematical models. Such a dynamical systems approach to elucidating patterns of intratumoral heterogeneity by integrating longitudinal experimental data with mathematical models can help design effective combinatorial and/or sequential therapies for better clinical outcomes.
REVIEW | doi:10.20944/preprints201709.0163.v1
Subject: Medicine & Pharmacology, Other Keywords: next-generation sequencing; whole-genome sequencing; hospital-acquired pneumonia; antibiotic resistance; prediction; clinical metagenomics
Online: 30 September 2017 (04:49:23 CEST)
Clinical metagenomics (CMg), referred to as the application of next-generation sequencing (NGS) to clinical samples, is a promising tool for the diagnosis of hospital-acquired pneumonia (HAP). Indeed, CMg allows identifying pathogens and antibiotic resistance genes (ARGs), thereby providing the information required for the optimization of the antibiotic regimen. Hence, provided that CMg would be faster than conventional culture, the probabilistic regimen used in HAP could be tailored faster, which should lead to an expected decrease of mortality and morbidity. While the inference of the antibiotic susceptibility testing from metagenomic or even genomic data is challenging, a limited number of antibiotics are used in the probabilistic regimen of HAP (namely beta-lactams, aminoglycosides, fluoroquinolones, glycopeptides and oxazolidinones). Accordingly in the perspective of applying CMg to the early diagnostic of HAP, we aimed at reviewing the performances of whole genomic sequencing (WGS) of the main HAP-causing bacteria (Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia and Staphylococcus aureus) for the prediction of susceptibility to the antibiotic families advocated in the probabilistic regimen of HAP.
Subject: Life Sciences, Biophysics Keywords: statistical mechanics; resource partitioning; distribution of species; seasonally dry tropical forest; biotic resistance
Online: 3 April 2019 (10:36:47 CEST)
Data on the seasonally dry tropical forests of Mexico have been examined in the light of statistical mechanics. The results suggest a division into two classes of species. There are drifting populations of a cosmopolitan class capable of existing in most dry forest sites; these have a statistical distribution previously only observed (globally) for populations of alien species. A high proportion of species found only at a single site are endemic and these prefer sites comparatively low in species richness.
ARTICLE | doi:10.20944/preprints202112.0452.v1
Subject: Mathematics & Computer Science, Other Keywords: Electrical Resistance Tomography (ERT); Raw Data Processing; Inline Swirl Separator; Geometrical Parameter Extraction
Online: 28 December 2021 (14:42:44 CET)
Electrical Resistance Tomography (ERT) has been used in the literature to monitor the gas-liquid separation. However, the image reconstruction algorithms used in the studies take a considerable amount of time to generate the tomograms, which is far above the time scales of the flow inside the inline separator and, as a consequence, the technique is not fast enough to capture all the rele-vant dynamics of the process, vital for control applications. This article proposes a new strategy based on the physics behind the measurement and simple logics to monitor the separation with a high temporal resolution by minimizing both the amount of data and the calculations required to reconstruct one frame of the flow. To demonstrate its potential, the electronics of an ERT system are used together with a high-speed camera to measure the flow inside an inline swirl separator. For the 16-electrode system used in this study, only 12 measurements are required to reconstruct the whole flow distribution with the proposed algorithm, 10x less than the minimum number of measurements of ERT (120). In terms of computational effort, the technique was shown to be 1000x faster than solving the inverse problem non-iteratively via the Gauss-Newton approach, one of the computationally cheapest techniques available. Therefore, this novel algorithm has the potential to achieve measurement speeds in the order of 104 times the ERT speed in the context of inline swirl separation, pointing to flow measurements at around 10kHz while keeping the aver-age estimation error below 6 mm in the worst case scenario.
ARTICLE | doi:10.20944/preprints202007.0579.v1
Subject: Life Sciences, Microbiology Keywords: Tolerance; Persistence; Cross-resistance; Toxin-antitoxin system; PemK/PemI; Klebsiella pneumoniae.
Online: 24 July 2020 (11:46:37 CEST)
Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that K. pneumoniae ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under CHLX pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemK/PemI. We characterized this PemK/PemI TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).
REVIEW | doi:10.20944/preprints202112.0088.v1
Subject: Medicine & Pharmacology, Obstetrics & Gynaecology Keywords: polycystic ovary syndrome; evolution; insulin resistance; infertility; environment; toxins; endocrine disrupting chemicals; dysbiosis; lifestyle; diet
Online: 6 December 2021 (15:34:25 CET)
Polycystic ovary syndrome (PCOS) is increasingly recognized as a complex metabolic disorder that manifests in genetically susceptible women following a range of negative exposures to nutritional and environmental factors related to contemporary lifestyle. The hypothesis that PCOS phenotypes are derived from a mismatch between ancient genetic survival mechanisms and modern lifestyle practices is supported by a diversity of research findings. The proposed evolutionary model of the pathogenesis of PCOS incorporates evidence related to evolutionary theory, genetic studies, in-utero developmental epigenetic programming, transgenerational inheritance, metabolic features including insulin resistance, obesity and the apparent paradox of lean phenotypes, reproductive effects and subfertility, the impact of the microbiome and dysbiosis, endocrine disrupting chemical exposure, and the influence of lifestyle factors such as poor quality diet and physical inactivity. Based on these premises, the diverse lines of research are synthesized into a composite evolutionary model of the pathogenesis of PCOS. It is hoped that this model will assist clinicians and patients to understand the importance of lifestyle interventions in the prevention and management of PCOS and provide a conceptual framework for future research. It is appreciated that this theory represents a synthesis of the current evidence and that it is expected to evolve and change over time.
ARTICLE | doi:10.20944/preprints201902.0011.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Cancer treatment, resistance to treatment, evolution of resistance, background extinctions
Online: 1 February 2019 (10:29:06 CET)
We propose the traditional goal of cancer therapists to develop a single drug or drug combination that can, by itself, eliminate all cancer cells within a host has neglected potential treatments that may achieve curative outcomes by strategically combining agents that are individually effective but non-curative. We derive basic principles for such an approach from the eco-evolutionary dynamics of background extinctions in which a “first strike” reduces the size and heterogeneity of the initial population and is followed immediately by demographic and ecological “second strikes” that push the population below an extinction threshold. This proposed strategy appears identical to the empirically-derived curative therapy in childhood Acute Lymphocytic Leukemia.
COMMUNICATION | doi:10.20944/preprints202007.0709.v1
Subject: Biology, Other Keywords: intrinsic multi-drug resistance; acquired multi-drug resistance; circulating tumor cells; single cells; cell clusters; cell monolayer; multi-cellular spheroids; cytometry of reaction rate constant; ovarian cancer
Online: 30 July 2020 (09:01:50 CEST)
Does cell clustering influence intrinsic and acquired multi-drug resistance (MDR) differently? To address this question, we studied cultured monolayers (representing individual cells) and cultured spheroids (representing clusters) formed by drug-naïve (intrinsic MDR) and drug-exposed (acquired MDR) lines of ovarian cancer A2780 cells by cytometry of reaction rate constant (CRRC). MDR efflux was characterized by accurate and robust “cell number vs. MDR efflux rate constant (kMDR)” histograms. Both drug-naïve and drug-exposed monolayer cells presented unimodal histograms; the histogram of drug-exposed cells was shifted towards higher kMDR value suggesting greater MDR activity. Spheroids of drug-naïve cells presented a bimodal histogram indicating the presence of two subpopulations with different MDR activity. In contrast, spheroids of drug-exposed cells presented a unimodal histogram qualitatively similar to that of the monolayers of drug-exposed cells but with a moderate shift towards greater MDR activity. The observed greater effect of cell clustering on intrinsic than on acquired MDR can help guide the development of new therapeutic strategies targeting clusters of circulating tumor cells.
ARTICLE | doi:10.20944/preprints202005.0337.v2
Subject: Biology, Plant Sciences Keywords: combined insect-resistance; QTNs; functional prioritization; fall armyworm; maize weevil; stem borers
Online: 1 June 2020 (02:19:01 CEST)
Several herbivores feed on maize in field and storage setups making the development of multiple-insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to FAW (fall armyworm) whilst bulked grains were subjected to MW (maize weevil) bioassay, genotyped with Diversity Array Technologies single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance level of 0.05 and 0.01, respectively, and located within or close to multiple-insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple-traits of which six were associated with resistance to both FAW and MW suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10-30kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of five of the six combined-resistance QTNs, thus, reinforcing the pleiotropy hypothesis. In addition, through In-silico co-functional network inferences, an additional 107 Network-based CGs (NbCGs), biologically connected to the 64 GbCGs, differentially expressed under biotic or abiotic stress were revealed within MIRGRs. The provided multiple-insect resistance physical map should contribute to the development of combined-insect resistance in maize.
REVIEW | doi:10.20944/preprints202009.0405.v1
Subject: Life Sciences, Microbiology Keywords: horizontal gene transfer; bacterial conjugation; phenotypic conversion; drug-resistance dissemination; bacterial biofilms; mobile plasmids; F plasmid
Online: 17 September 2020 (12:00:29 CEST)
Bacterial conjugation, also referred to as bacterial sex, is a major horizontal gene transfer mechanism where the DNA is transferred from a donor to a recipient bacterium by direct contact. Conjugation is universally conserved among bacteria and occurs in a wide range of environments (soil, plant surfaces, water, sewage, biofilms and host-associated bacterial communities). Within these habitats, conjugation drives the rapid evolution and adaptation of bacterial strains by mediating the propagation of various metabolic properties, including symbiotic life-style, virulence, biofilm formation, or resistance to heavy metals and, most importantly, resistance to antibiotics. These properties make of conjugation a fundamentally important process at the center of extensive study. Here, we review the key steps of conjugation by following the life-cycle of the F plasmid during transfer from the donor to the recipient cell. We also discuss our current knowledge of the extent and impact of conjugation within an environmentally and clinically relevant bacterial habitat, bacterial biofilms.
ARTICLE | doi:10.20944/preprints202004.0164.v2
Subject: Biology, Ecology Keywords: drought; climate variability; resilience; resistance; estuary; fish; extreme events; Delta Smelt; Chinook Salmon; Largemouth Bass
Online: 23 July 2020 (10:30:03 CEST)
Many estuarine ecosystems and the fish communities that inhabit them have undergone substantial changes in the past several decades, largely due to multiple interacting stressors that are often of anthropogenic origin. Few are more impactful than droughts, which are predicted to increase in both frequency and severity with climate change. In this study, we examined over five decades of fish monitoring data from the San Francisco Estuary, California, U.S.A, to evaluate the resistance and resilience of fish communities to disturbance from prolonged drought events. High resistance was defined by the lack of decline in species occurrence from a wet to a subsequent drought period, while high resilience was defined by the increase in species occurrence from a drought to a subsequent wet period. We found some unifying themes connecting the multiple drought events over the fifty-year period. Pelagic fishes consistently declined during droughts (low resistance), but exhibit a considerable amount of resiliency and often rebound in the subsequent wet years. However, full recovery does not occur in all wet years following droughts, leading to permanently lower baseline numbers for some pelagic fishes over time. In contrast, littoral fishes seem to be more resistant to drought and may even increase in occurrence during dry years. Based on the consistent detrimental effects of drought on pelagic fishes within the San Francisco Estuary and the inability of these fish populations to recover in some years, we conclude that freshwater flow remains a crucial but not sufficient management tool for the conservation of estuarine biodiversity.
ARTICLE | doi:10.20944/preprints202301.0110.v1
Subject: Life Sciences, Microbiology Keywords: AAC(2′)-Ia; aminoglycoside 2′-N-acetyltransferase type Ia; aminoglycoside; multidrug resistance; metal ions; plazomicin; adjuvant
Online: 6 January 2023 (02:26:45 CET)
Plazomicin is a recently U.S. Food and Drug Administration (FDA)-approved semisynthetic aminoglycoside. Its structure consists of a sisomicin scaffold modified by adding a 2(S)-hydroxy aminobutyryl group at the N1 position and a hydroxyethyl substituent at the 6′ position. These substitutions produced a molecule refractory to most aminoglycoside-modifying enzymes. The main enzyme within this group that recognizes plazomicin as substrate is the aminoglycoside 2′-N-acetyltransferase type Ia [AAC(2′)-Ia], which reduces the antibiotic’s potency. Designing formulations that combine an antimicrobial with an inhibitor of resistance is a recognized strategy to extend the useful life of existing antibiotics. We have recently found that several metal ions inhibit acetylation of numerous aminoglycosides catalyzed by the aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib]. In particular, Ag1+, which also enhances the effect of aminoglycosides by other mechanisms, is very effective in interfering with AAC(6′)-Ib-mediated resistance to amikacin. Here we report that silver acetate is a potent inhibitor of AAC(2′)-Ia-mediated acetylation of plazomicin in vitro, and it reduces resistance levels of Escherichia coli carrying aac(2′)-Ia. The resistance reversion assays produced equivalent results when the structural gene was expressed under the control of the natural or the blaTEM-1 promoters. The antibiotic effect of plazomicin in combination with silver was bactericidal, and the mix did not show significant toxicity to human embryonic kidney 293 (HEK293) cells.
ARTICLE | doi:10.20944/preprints202009.0496.v1
Subject: Social Sciences, Education Studies Keywords: cultural competence; evolution teaching; religious cultural competence in evolution education; action research; resistance to evolution learning
Online: 21 September 2020 (04:33:34 CEST)
Acknowledging the diverse perceptions about science-religion relationships among learners who come from various religious environments may increase learners’ willingness to learn about evolution. This study is based on a zoology course designed for in-service teachers, which aimed to provide basic scientific knowledge about evolution using the Religious Cultural Competence in Evolution Education framework. The study explores whether learners who were resistant to evolution modify their attitudes and willingness to learn about it, and whether they develop respect toward learners who hold contradicting views. Using qualitative methods, the findings indicate that using the Religious Cultural Competence in Evolution Education framework increased some formerly "resistant" learners’ willingness to learn about evolution and include it in their own teaching, albeit in varying degrees and with various reservations. The learners appreciated the freedom to express their challenges concerning evolution learning or teaching and became more willing to respect opposing perspectives, even though not all the religious learners accepted evolution as an explanation for the development of organisms. This study has international implications for bridging the gap between science and religion, thus reducing resistance to learning and teaching about evolution.
ARTICLE | doi:10.20944/preprints201912.0093.v1
Subject: Life Sciences, Genetics Keywords: mixed linear model; genotyping-by-sequencing; functional validation; RT-qPCR; resistance genes; GWAS
Online: 7 December 2019 (12:41:39 CET)
Meloidogyne javanica causing root-knot nematode in soybean is an important problem in soybean areas, leading to several yield losses. Some accessions have been identified carrying resistance loci to this nematode specie. In this study, a set of 317 soybean accessions were characterized for resistance to M. javanica. Genome-wide association study (GWAS) was performed using SNPs from genotyping-by-sequencing (GBS), and a region of 29.2 Kbp on chromosome 13 was identified. The haplotype analysis showed that SNPs were able to discriminate susceptible and resistant accessions, leading to 25 accessions sharing the resistance locus. Furthermore, 5 accessions may be new M. javanica resistance sources. The screening of the SNPs in the USDA soybean germplasm showed that several accessions previous reported as resistance to other nematodes also showed the resistance haplotype on chromosome 13. High levels of concordance among the phenotypes of Brazilian cultivars and the SNPs in chromosome 13 were observed. A in silico analysis of the mapped region on soybean genome revealed a presence of 5 genes with structural similarity with major resistance genes. The expression levels of the candidate genes in the interval demonstrated a potential pseudogene, and other two model genes up-regulated in the resistance source after pathogen infection. The SNPs associated to the region conferring resistance is a important tool for introgression of the resistance by marker-assisted selection in soybean breeding programs.
ARTICLE | doi:10.20944/preprints201809.0077.v1
Subject: Life Sciences, Microbiology Keywords: Garlic, Antibiotics, Lomé, Uropathogenic bacteria, Urinary Tract Infection, Multidrug resistance and alternative therapy.
Online: 5 September 2018 (01:35:46 CEST)
The urinary tract infection (UTI) is the most common bacterial infection, especially in women. The increased incidence of UTIs, at the last decades have paralleled with the growing emergence of antibiotic resistance. The aim is to evaluate aqueous garlic extract (AGE) susceptibility against multidrug-resistant (MDR) bacteria isolated in urine of women. The investigation of antibacterial propriety and time kill effect of AGE was performed by the well method, microdilution method and spectrophotometer assay. Antibiotics susceptibility assay revealed that the nine MDR bacteria had high resistance against Amoxicillin/ clavulanic acid (100%) and Erythromycin (100%), Cefotaxime (83.33%) and Ceftazidime (83.33%). AGE exhibited potent antibacterial activity against the nine MDR bacteria tested. In Gram-negative bacteria, the inhibition diameters ranged from 20 ± 3 to 32 ± 4 mm, with Minimum Inhibitory Concentrations (MICs) ranging from 10% to 12.5% (w/v) and Minimum Bactericidal Concentration (MBCs) was 12.5 % (w/v). Gram-positive bacteria exhibited diameters ranging from 38 ± 2 to 45 ± 1 mm; MIC and MBC values ranged from 05 to 10 % (w/v) and were found more susceptible than Gram-negative bacteria. To conclude, this investigation shown that AGE have high potential antibacterial to use as an alternative to treat women UTIs.
ARTICLE | doi:10.20944/preprints202104.0456.v1
Subject: Life Sciences, Biochemistry Keywords: ethidium; tetraphenylphosphonium; multidrug resistance; outer membrane permeability; efflux inhibitor; phenylalanyl-arginyl-β-naphtylamide, Polymyxin B
Online: 18 April 2021 (10:14:56 CEST)
Bacterial resistance to antibiotics due to an increased efficiency of the efflux is a serious problem in clinics of infectious diseases. Knowledge of the factors affecting the activity of efflux pumps would help to find the solution. For this, fast and trustful methods for the efflux analysis are needed. Here we analyzed how the assay conditions affect the accumulation of efflux indicators ethidium (Et+) and tetraphenylphosphonium in Salmonella enterica ser. Typhimurium cells. An inhibitor phenyl-alanyl-arginyl-β-naphtylamide was applied to evaluate the input of RND family pumps into the total efflux. In parallel to spectrofluorimetric analysis, we used an electrochemical assessment of Et+ concentration. Results of our experiments indicated that Et+ fluorescence increases immediately after the penetration of this indicator into the cells. However, when cells bind a high amount of Et+, intensity of the fluorescence reaches the saturation level and stops reacting to the accumulated amount of this indicator. For this reason, electrochemical measurements provide more trustful information about the efficiency of efflux when cells accumulate high amounts of Et+. Measure-ments of Et+ interaction with the purified DNA demonstrated that affinity of this lipophilic cation to DNA depends on the medium composition. The capacity of DNA to bind Et+ considerably de-creases in presence of Mg2+, Polymyxin B or when DNA is incubated in high ionic strength media.
Subject: Medicine & Pharmacology, Allergology Keywords: VIM; Enterobacteriaceae; mercury; resistance
Online: 14 June 2021 (11:13:01 CEST)
The emergence of carbapenemase-producing Enterobacteriaceae has limited therapeutic options and presents a major public health problem. Resistances against carbapenems in this bacterial family are mostly conveyed by metallo-beta-lactamases (MBL) including VIM, which are often encoded on resistance plasmids. We characterized four VIM-positive isolates that were obtained as part of a routine diagnostic screening from two laboratories in north-eastern Germany be-tween June and August 2020. Whole-genome sequences were generated to address a) their phylo-genetic properties, b) their plasmid content, and c) the underlying mechanisms of resistance and virulence. In addition, we performed phenotypic antibiotic and mercury resistance analyses. The genomic analysis revealed three different bacterial species including C. freundii, E. coli and K. oxytoca with four different sequence types. All isolates were geno- and phenotypically multi-drug-resistant (MDR). Three isolates of four carried identical VIM-1-resistance plasmids, which – in addition – encoded for a mercury resistance operon and showed some similarity to two ex-ternal plasmid sequences. The distribution of virulence features among the genomes was limited. Our results highlight the circulation of an identical VIM-1-resistance plasmid in three of four bacterial isolates of different Enterobacteriaceae in north-eastern Germany.
ARTICLE | doi:10.20944/preprints202106.0349.v1
Online: 14 June 2021 (10:36:45 CEST)
Resistance training increases myofiber hypertrophy, but the morphological adaptations that occur within myofibers remain largely unresolved. Fifteen males with minimal training experience (24±4 years, 17.9±1.4 kg/m2 lean body mass index) performed 10 weeks of conventional, full-body resistance training (2x weekly). Body composition, the radiological density of the vastus lateralis muscle using peripheral quantitative computed tomography (pQCT), and vastus lateralis muscle biopsies were obtained one week prior to and 72 hours following the last training bout. Fiber typing and the quantification of myofibril and mitochondrial areas per fiber were performed using histology/immunohistochemistry (IHC) techniques. Relative myosin heavy chain and actin protein abundances per wet muscle weight as well as citrate synthase (CS) activity assays were also obtained on tissue lysates. Training increased whole-body lean mass, mid-thigh muscle cross-sectional area, various strength metrics, and mean and type II fiber cross sectional areas (fCSA) (p<0.05). Myofibril areas in type I or II fibers were not altered with training, suggesting a proportional expansion with fCSA increases. Relative myosin heavy chain and actin protein abundances also did not change with training. IHC indicated training increased mitochondrial areas in both fiber types (p=0.018). However, CS activity levels remained unaltered with training. Interestingly, although pQCT-derived muscle density increased with training (p=0.036), suggestive of myofibril packing, a positive association existed between training-induced changes in this metric and changes in type I+II myofibril areas (r=0.600, p=0.018). Shorter-term resistance training seemingly involves a proportional expansion of myofibrils and an accelerated expansion of mitochondria in type I and II fibers. Additionally, histological and biochemical techniques should be viewed independently from one another given the lack of agreement between the variables assessed herein. Finally, the pQCT may be a viable tool to non-invasively track morphological changes in muscle tissue.
ARTICLE | doi:10.20944/preprints201912.0215.v1
Online: 16 December 2019 (11:29:09 CET)
Klebsiella pneumoniae, a major cause of both hospital and community-acquired infections, is listed by the World Health Organization as a critical priority antibiotic- resistant bacterial pathogen. With the appearance of sequencing techniques such as Next-generation Sequencing (NGS), there is the possibility to obtain the whole genome of the bacteria, getting to know all antimicrobial resistance determinants. The purpose of this study has been to apply this new technology to clinical microbiology, in order to characterize the resistome present in carbapenem-resistant K.pneumoniae strains isolated in a tertiary hospital in Valencia, Spain. A total of 234 isolates were prepared for whole-genome sequencing with Ilumina MiSeq, and sequences were later studied for antimicrobial resistance genes, sequence-typing and plasmids. Sequence-typing showed four major circulating clones in our hospital settings: ST11, ST307, ST101 and ST147, carrying different plasmids and different resistance determinants such as OXA-48 and NDM-1 carbapenemase. Application of new technologies such as whole-genome sequencing in clinical microbiology gives advantages when it comes to rapid therapy adjustment, consequently improving the patient’s clinical outcomes.
ARTICLE | doi:10.20944/preprints201801.0136.v1
Subject: Materials Science, Nanotechnology Keywords: polymer-drug association; inclusion nano-complex; an amphiphilic polymer; polysoaps; antibiotic resistance; ampicillin trihydrate
Online: 16 January 2018 (07:56:15 CET)
Biocompatible polymeric materials with potential to form functional structures in association with different therapeutic molecules have a high potential for biological, medical and pharmaceutical applications. Therefore, the protective capability of the inclusion nano-Complex formed between the sodium salt of poly(maleic acid-alt-octadecene) and a β-lactam drug (ampicillin trihydrate) on the chemical, enzymatic and biological degradation was evaluated. PAM-18Na was produced and characterized as reported previously. The formation of polymeric hydrophobic aggregates in aqueous solution was determined, using pyrene as a fluorescent probe. Furthermore, the formation of polymer-drug nano-complexes was characterized by Differential Scanning Calorimetry-DSC, viscometric, ultrafiltration/centrifugation assays, zeta potential and size measurements by dynamic light scattering-DLS. The PAM-18Na capacity to avoid the chemical degradation was studied through stress stability tests. The enzymatic degradation was evaluated from a pure β-lactamase, while the biological degradation was determined by different β-lactamase producing Staphylococcus aureus strains. When ampicillin was associated with PAM-18Na, the half-life time in acidic conditions increased, whereas both the enzymatic degradation and the minimum inhibitory concentration decreased to a 90 and 75%, respectively. These results suggest a promissory capability of this polymer to protect the β-lactam drugs against chemical, enzymatic and biological degradation.
ARTICLE | doi:10.20944/preprints201712.0024.v1
Subject: Life Sciences, Virology Keywords: HIV-1; quasispecies; minority resistance mutations; HAART; drug resistance; undetectable viral load
Online: 4 December 2017 (09:34:16 CET)
Increased access to highly active antiretroviral therapy (HAART) by HIV+ individuals has become a reality worldwide. In Brazil, ART currently reaches over half of the HIV-infected subjects. In the context of a remarkable HIV-1 genetic variability, highly related variants, called quasispecies, are generated. HIV quasispecies generated during infection can influence virus persistence and pathogenicity, representing a challenge to treatment. However, the clinical relevance of minority quasispecies is still uncertain. For this study, we have determined the archived proviral sequences, viral subtype and drug resistance mutations from a cohort of HIV+ patients with undetectable viral load undergoing HAART as first-line therapy using next-generation sequencing for near full-length virus genome (NFLG) assembly. HIV-1 consensus sequences representing NFLG were obtained for eleven patients, while for another twelve varying genome coverage rates were obtained. Phylogenetic analysis showed the predominance of subtype B (83%; 19/23). Considering the minority variants, 18 patients carried archived virus harboring at least one mutation conferring antiretroviral resistance; for six patients, the mutations correlated with the current ARVs used. These data highlight the importance of monitoring HIV minority drug resistant variants and their clinical impact, to guide future regimen switches and improve HIV treatment success.