Biology and Life Sciences

Abstract: Background: Due to the difficulty of identifying the window of receptivity, a molecular understanding of endometrial changes after fertilization is essential for improving the effectiveness of in vitro fertilization (IVF). This multi-level study examines the compo-sition of cytokines and extracellular vesicles (EVs) in uterine lavage samples obtainable via a noninvasive procedure in mice. The goal is to offer a new perspective on the tim-ing of embryo transfer. Methods: We performed flow cytometric analyses of inflamma-tory cytokines and EVs in uterine lavage samples collected from CD1 mice at the pre-receptive stage (2.5 days post coitum [dpc]) and the receptive stage (4.5 dpc). We also assessed endometrial progesterone receptor expression via immunohistochemistry and evaluated the expression of adhesion molecules related to implantation by RT-PCR. Re-sults: Significant differences were found in the concentrations of inflammatory cyto-kines (IL-6, IFN-γ, and MCP-1), the EV pattern in uterine lavage fluid, and the expres-sion of some genes related to implantation (CD44, CD81, and CD29). These results re-veal uterine lavage fluid markers associated with endometrial receptivity. Using these noninvasive markers can improve the effectiveness of IVF by enabling more precise timing of embryo transfer.

Abstract: Backround: Musculoskeletal disorders associated with muscular strain on the neck and shoulders affect women in administration more often than men. Ergonomic guidelines have historically been derived from male models, often ignoring biomechanical differences between the sexes. The study aims to quantify the acute biomechanical response of the neck muscles of men and women to a standardized writing task. Methods: The research involved 57 healthy university students (34 women, 23 men; age 19–24 years). Muscle tone (F), stiffness (S), and viscoelastic decrement (D) in sternocleidomastoideus muscle (SCM), trapezius muscle (UT), and semispinalis capitis muscle (SSC) were assessed by the non-invasive MyotonPRO device before and after 20 minutes of continuous writing. Results: The results were statistically quantified and showed significant differences in muscle strategy between the sexes (p < 0.05). While women experienced a fatigue decrease in tone after exercise, the SCM as a superficial neck flexor and the deeper neck extensor SSC recorded a significant compensatory increase in tone, the opposite was true for men. Conslusion: These objective data show that identical office work causes a different physiological burden in women. Prevention of musculoskeletal disorders should therefore abandon a one-size-fits-all approach and move towards gender-specific solutions.

Abstract: Previous studies on rats showed a deterioration of left ventricular (LV) function and myocardial injury characterized by oxidative/nitrosative stress, PARylation, and apoptosis in the heart after three days of hypoxia. In the present study on rats, we investigated whether a three-day recovery period in normoxia can reverse myocardial injury and dysfunction. Further, we studied the effects of norepinephrine (NE) administration as a model of strong sympathetic activation on hypoxia-induced LV dysfunction and myocardial damage, as well as their reversibility. Three days of normobaric hypoxia (10% O2) significantly decreased LV systolic function. Contrary to our expectations, NE infusion even aggravated the depression in LV function. These dysfunctions were completely reversed after three days of normoxic recovery. In contrast, nitrotyrosine as a marker of oxidative/nitrosative stress receded only partially, and poly-ADP-ribose (PAR) increased even further during the recovery period. Apoptosis-inducing factor receded at least partially indicating that PAR-related apoptosis (parthanatos) is not a major cause of hypoxia-induced LV dysfunction. Additional administration of NE mildly aggravated oxidative/nitrosative stress but did not significantly intensify PARylation and consequently, parthanatos. The findings demonstrate that hypoxia-induced LV dysfunction is reversible suggesting that subchronic hypoxia and subsequent reoxygenation has a better prognosis for the LV than classical ischemia/reperfusion injury.

Abstract:

Background: The local twitch response (LTR) elicited during ultrasound-guided fascial hydrorelease (FHR) is conventionally attributed to dysfunctional motor endplates. However, in a related observational paper under concurrent submission, 89/89 evaluable archived LTR events were observed within stacking fascia at sites incompatible with direct endplate excitation. Hypothesis: We propose the Fascial Capacitor Model: stacking fascia functions as a multilayer biological capacitor in which collagen sublayers act as electrodes and the interposed densified hyaluronic-acid (HA)-rich loose layer acts as the dielectric, with the LTR reinterpreted as a transient electrophysiological discharge when a needle bridges its layers. This biophysical model is explicitly grounded in the established molecular and histological architecture of human deep fascia. Supporting evidence: Each premise is independently supported by primary literature from at least eight research lines spanning roughly seventy years. Voltage gap: The apparent gap between estimated bulk discharge voltages and motor neuron threshold is resolved by reconsidering needle-tip geometry and stimulation modality, anchored by the ±6 V triboelectric measurements of Ouyang et al. (2022). Implications: The model is the immediate-phase complement to the Fascial Memory Reset Hypothesis (Int J Mol Sci 2026, 27, 3720), explains intra-procedural symptom relief, and yields falsifiable predictions. A direct empirical validation programme using insulating-needle SEA recording is in preparation at the corresponding author’s institution.

Abstract: Time-restricted feeding (TRF) has emerged as a promising intervention to improve metabolic health and promote healthy aging, yet the cellular mechanisms underlying its effects remain incompletely understood. Here, we applied imaging-based and quantitative cellular analyses to investigate how TRF modulates aging-associated and neurodegeneration-related phenotypes in vitro. Human fibroblasts and AC16 cardiomyocytes were used as models of cellular aging, alongside fibroblast-based models of neurodegeneration. TRF was simulated through cyclic nutrient availability, and cellular responses were evaluated using microscopy-based assessment of cellular morphology, senescence-associated features, metabolic state, and circadian rhythm-associated gene expression dynamics. Imaging analyses demonstrated that TRF modulated key hallmarks of cellular senescence, including changes in cell morphology and intracellular organization, consistent with enhanced cellular resilience and altered metabolic adaptation. In AC16 cardiomyocytes, TRF influenced aging-associated cellular phenotypes, indicating that its effects extend beyond proliferative cell systems to cardiac-relevant models. In neurodegeneration-associated fibroblast models, TRF altered disease-related cellular signatures and stress-associated phenotypes, supporting a potential protective role in neurodegenerative conditions. Quantitative analyses further revealed significant TRF-induced changes in circadian rhythm characteristics across all models, including altered oscillatory amplitude, supporting a mechanistic link between nutrient timing and cellular timekeeping. Together, these findings demonstrate that TRF induces measurable changes in cellular architecture and circadian regulation associated with improved aging- and neurodegeneration-related phenotypes. This work highlights the utility of imaging-based approaches for investigating the spatiotemporal cellular effects of metabolic interventions and supports TRF as a potential therapeutic strategy for age-associated diseases.

Abstract: Background: An estimated 28,900 deaths around the world in 2021 were attributed to unintentional CO poisoning. Following inhalation, CO binds to hemoglobin with an affinity 220–240 times greater than that of oxygen to form carboxyhemoglobin (COHb). While the constituents of CO exposure are known to determine CO uptake in the blood, much less is understood regarding individual variability of the response to a given CO stimulus. Thus, the purpose of this paper was to explore the relationship between hemoglobin mass (HbM, a proxy for blood hemoglobin content) and the magnitude of the ensuing carboxyhemoglobinemia. Methods: This is a theoretical work based solely on considerations and published data. Discussion: Currently considered the gold standard for HbM assessment, the CO-rebreathing technique relies on the dilution principle i.e. the lower the HbM values the higher the ΔCOHb following a standardized CO bolus administration or an outdoors exposure. Accordingly, previously published prediction equations with HbM and ΔCOHb as the predictor and outcome variables, respectively, are reviewed with particular reference to the (confounding) factor of pulmonary ventilation. As far as treatment to CO poisoning is concerned, dynamic exercise emerges as a supplement to oxygen therapy to facilitate CO removal from human body. Screening procedures aiming to identify individuals susceptible to CO poisoning should henceforth include HbM assessments.

Abstract: Although athlete monitoring can quantify training exposure and athlete status with increasing detail, conversion into daily training decisions remains inconsistent. This structured narrative review synthesizes evidence on training load, neuromuscular readiness, recovery, fatigue interpretation, measurement reliability, applied decision-making, and proposes the LOAD-R framework: a systems model linking Load, Organism response, Adaptive state, Decision, and Re-evaluation. A transparent non-PRISMA strategy was used because the aim was conceptual integration and framework development rather than effect-size pooling. Evidence was organized around field-applicable monitoring domains and their decision value. LOAD-R extends existing approaches by moving beyond single indicators, fixed thresholds, and dashboard alerts. It classifies athlete state into adaptive, functional-overload, underloaded, uncertain, or maladaptive zones, each linked to progress, maintain, modify, deload, or recover decisions. The framework also provides implementation levels and testable predictions. By shifting monitoring from passive data collection toward adaptive decision support, LOAD-R offers a scalable model that may improve decision consistency, reduce maladaptive training responses, and enhance the practical value of athlete monitoring in applied sport settings.

Abstract: Osteoporosis arises from disrupted bone remodeling, and growing evidence shows that gut microbiota and their metabolites have a major influence on skeletal health through the gut-bone and gut-brain-bone axes. In this systematic review, we synthesize findings from 932 studies to identify key microbial taxa, metabolites, and signaling pathways that modulate osteoblast and osteoclast activities. Short‑chain fatty acids (SCFA), tryptophan‑derived metabolites, and β‑D‑glucuronidase-related estrogen regulation emerge as central microbial mechanisms affecting bone formation and resorption. By integrating these data with the Phylobone extracellular matrix proteins database, we highlight Osteopontin and Cathepsin K as important downstream mediators linking microbial signals to bone matrix turnover. Probiotic strains (particularly Lactobacillus rhamnosus GG and L. reuteri) show potential to improve bone health through metabolic, immune, and endocrine pathways. Together, these findings outline a mechanistic framework connecting gut function to skeletal biology and identify promising microbiome‑based targets for osteoporosis interventions.

Abstract: Background/Objectives: This study aimed to quantify the kinetic demands of multiple hops in series, movement tasks that are commonly used in strength and conditioning and physiotherapeutic practice. Focus was placed on comparing the demands of a quintuple-hop task to a triple-hop task, with particular focus on quantifying the eccentric braking stretch-load demands. Methods: Forty-four male university athletes (age 20.1 ± 1.4 years; body mass 71.2 ± 8.6 kg; stature 171.9 ± 5.1 cm) completed the hopping tasks across track-embedded force platforms, where braking and propulsion kinetics were measured across 54x track-embedded force platforms. Results: Significant (p < 0.001) averaged in-creases in maximal vertical (~32%) and horizontal braking impulses (~56%) for both TH and QH tasks were noted across hops. The last two hops of the QH task were found to have greater averaged vertical (~58%) and horizontal (~180%) stretch-load demands than the two initial hops (p < 0.001). Conclusions: This is the first study in which an extensive summary of kinetic measures for both triple and quintuple hops has been reported. The findings highlight the biomechanical, stretch-load aspects of these exercises, which can help practitioners better prescribe and program hops for injury prevention, rehabilitation, and performance enhancement.

Abstract: Background: Motor precision is a highly innate trait, while ambidexterity in high-precision tasks remains rare and biologically regulated. Few sports necessitate bilateral precision; however, the indigenous sport of picigin uniquely requires symmetrical palm-striking proficiency. Methods: This study investigated bilateral precision and ball velocity in 22 experienced players, divided into competitive (n=11) and recreational (n=11) groups. A specialized bilateral palm-precision test was developed to measure performance across both dominant and non-dominant hands. Key metrics included the asymmetry index for speed and accuracy, and the speed-accuracy trade-off (SAT). Results: Results indicate that competitors significantly outperform recreational players in both precision and velocity. Notably, the SAT analysis suggests that the dominant hand of recreational players performs at a level comparable to the non-dominant hand of competitors. While recreational players exhibited slightly lower asymmetry indices, the inter-manual gap remained stable despite years of experience. Conclusions: Findings suggest that bilateral training induces linear improvements on both sides, maintaining a constant asymmetry ratio rather than diminishing it through long-term practice.

Abstract: Dental pain due to dentine hypersensitivity or pulpitis is characterized by short or lasting episodes of pain triggered by normally innocuous stimuli originating from exposed dentine. Both represent the most frequent pain of the orofacial region. Transient receptor potential (TRP) superfamily of ion channels participates in the detection of different modalities of sensibility in the mammalian sensory teeth system, i.e., trigeminal neurons and odontoblasts. In particular, some members of the melastatin family (TRPM) serve as molecular thermal sensors, and temperature is one of the most potent stimuli in triggering dentine hypersensitivity. Here we review and update the information about the distribution of TRPM channels in the trigeminal ganglion and dental pulp cells, especially odontoblast, in humans and animal models. In addition to the well know sensory roles of TRPM, other functions such as in development and mineralization of teeth are considered.

Abstract: To maintain homeostatic conditions and optimal function during stressors, mitochondria initiate nuclear retrograde signaling. The mitochondrial Integrated Stress Response (ISR) and Unfolded Protein Response (UPR^mt) are critical quality control mechanisms activated during instances of mitochondrial perturbations. Restoration of mitochondrial homeostasis is orchestrated by three transcription factors, ATF4, CHOP, and ATF5, which upregulate protective genes to counteract stress. As the health and function of skeletal muscle is heavily dependent on a highly adaptive mitochondrial network, defining how mitochondrial health is maintained across various conditions is essential. Although several studies demonstrate the importance of these responses following instances of stress, the signaling mechanisms required to initiate such pathways remain poorly characterized in skeletal muscle. This review examines how the mitochondrial ISR/UPRmt and related transcription factors respond to organellar stress by emphasizing the molecular events that occur during exercise, aging and muscle disuse. Through consolidating the literature, this work aims to highlight the current understanding of mitochondrial stress response signaling within skeletal muscle and thus emphasize areas for future research and potential therapeutic strategies during divergent metabolic conditions.

Abstract: The teaching of human anatomy has historically relied on cadaveric dissection, atlases, and static imaging. While these approaches remain foundational, they insufficiently reflect the dynamic, bedside-oriented realities of modern clinical practice. Point-of-care ultrasound (POCUS) enables real-time visualization of living anatomy and physiology and is increasingly integral to clinical decision-making across specialties. I argue that sonographic anatomy should be incorporated longitudinally into all undergraduate medical curricula. Such integration enhances spatial understanding, reinforces clinical relevance, and accelerates the development of diagnostic reasoning. I propose a scalable, phased implementation model and address common barriers, including faculty training and resource constraints. The integration of ultrasound into anatomy education represents not an addition, but a necessary evolution.

Abstract: Elucidating the pathophysiological mechanisms of mental disorders remains a critical challenge in psychiatric research. Recent studies have highlighted the potential involvement of cytoskeletal and molecular motor abnormalities in the development of mental disorders such as schizophrenia and autism spectrum disorder (ASD). Although schizophrenia and ASD differ clinically, both disorders are increasingly regarded as neurodevelopmental conditions and share vulnerabilities in synapse formation and neural circuit maturation. This review synthesizes the latest findings on the relationship between cytoskeletal and molecular motor abnormalities and mental disorders. The cytoskeleton, composed of microtubules, actin filaments, and intermediate filaments, along with molecular motors such as kinesins, dyneins, and myosins, plays crucial roles in neurodevelopment, synapse formation, and neurotransmission. In schizophrenia, decreased expression of the microtubule-associated protein MAP2 and abnormalities in the DISC1 gene have been reported, potentially leading to dendritic morphological abnormalities and neurodevelopmental disorders. Additionally, abnormalities in molecular motors such as KIF17 and KIF1A have been implicated in schizophrenia pathophysiology. Myosin Id has been identified as a risk gene for ASD. Furthermore, abnormalities in actin-related proteins such as SHANK3 and CYFIP1 have been shown to cause synaptic dysfunction. These findings suggest that mental disorders arise from complex pathologies involving multiple cytoskeletal and molecular motor-related protein abnormalities. Future research should focus on elucidating the functions of individual proteins and adopting a comprehensive approach that includes glial cells. Advances in this field may deepen our understanding of the pathophysiological mechanisms of mental disorders and potentially lead to the development of novel therapeutic strategies.

Abstract: Post-COVID syndrome has been associated with potentially impaired exercise capacity. Here, we postulate that machine learning models trained on near-infrared spectroscopic (NIRS) signals collected during different physical activity states from four optodes over the quadriceps, using features selected by principal component analysis (PCA), can detect distinct patterns of oxygenation. These patterns differentiate post-COVID syndrome from healthy controls and are not evident from traditional analysis of NIRS signals. 228 time-series NIRS datasets from four optodes over different quadriceps regions were collected across multiple activity states in post-COVID syndrome and healthy participants. PCA was performed to reduce dimensionality and identify data patterns. K-Nearest Neighbour with Dynamic Time Warping, Canonical Interval Forests (CIF) and Convolutional Neural Network (CNN) models were trained on NIRS-derived features to classify post-COVID syndrome -related muscle abnormalities versus healthy responses. PCA revealed that tissue oxygenation index (StiO2) was the most effective parameter separating the populations, whereas the normalised total haemoglobin index (nTHI) was most sensitive to activity states. Learning models incorporating StiO2 and nTHI, exhibited excellent performance in distinguishing between populations, with CIF and CNN exhibiting best performance (Kappa>0.69, F1-score>0.85, Sensitivity>0.85, Precision>0.88, Accuracy>0.85, AUC>0.95). However, local muscle StiO2 heterogeneity and StiO2 on-transient mean response time did not show significant differences between populations. Our findings demonstrate the efficacy of learning models trained on time-series muscle oxygenation data for detecting distinct muscle oxygenation patterns in post-COVID syndrome participants. This provides a novel, non-invasive approach applicable at the individual level for identifying distinctive muscle oxygenation patterns, where traditional analytical methods lack sensitivity.

Abstract: Background: Contextual interference (CI), defined as interleaved practice, improves motor skill learning in powerlifters. However, previous protocols lacked ecological validity. This study evaluated an alternative, highly specific CI exercise (the seal row) to provide a more practical approach for powerlifting routines. Methods: Fifteen powerlifters (10 males and 5 females, age: 23 ± 2 years, 1RM: 78 ± 32 kg) were randomized in high CI group (HCI) and low CI group (LCI) undergoing a 6-week training intervention. Powerlifters were tested on their bench press exercise strength and technical execution. Technical execution was assessed using a 13-item Likert scale. Results: Strength significantly increased in both groups (F (3.42, 46.5) = 9.553, p &lt; 0.05). Global technique analysis showed a group × time interaction (F (4,952) = 2.547, p = 0.038, pes = 0.01). A significant group × time interaction occurred for scapular adduction (F (2.98, 38.76) = 4.118, p = 0.013), with the HCI group showing greater improvement. Conclusions: Alternating a primary task (bench press) with antagonist overloads (seal row) improves technical execution over six weeks without hindering strength gains. These findings support practical CI strategies in resistance training to optimize skill acquisition.

Abstract: Contemporary models of resistance training often treat repetitions within a set as interchangeable, emphasize only those performed near failure, or prescribe controlled tempos that moderate effort across repetitions. These perspectives leave unclear how moment-to-moment intent and movement quality interact to determine where fatigue and adaptation are localized. We introduce the Targeted Intensity Cumulation (TIC) model, a minimal mechanistic framework in which high voluntary intent combined with high purity technique progressively concentrates mechanical and metabolic stress within target musculature across repetitions and sets. In this formulation, the rate of performance decay (e.g., as measurable by decline in concentric velocity) serves as an observable proxy for stimulus localization. The model provides a unifying account for (1) hypertrophy equivalence across repetition ranges, (2) the continuous accumulation of training stimuli, (3) exercise-specific 'performance cliffs,' and (4) cross-load performance transfer. By shifting the focus from external load to the internal state-space of intent and constraint, TIC generates testable predictions for optimizing training execution and monitoring.

Abstract: Heat stress (HS) has emerged as a major environmental stressor, inducing oxidative stress, hepatic steatosis and impairing production performance and health in laying hens, with limited evidence-based nutritional interventions available. This study investigated the hepatoprotective effects of dietary silymarin (SIL) against chronic HS. In a 10-week trial, 252 43-week-old Hy-Line Brown hens were exposed to daily HS (32 ± 1℃, temperature-humidity index [THI] > 73) and fed either a basal diet or one supplemented with 100 mg/kg SIL. SIL significantly increased laying rate (P < 0.05) and improved albumen height, Haugh units, and shell strength by week 8 (P < 0.05). Histological analysis showed a 48% reduction in non-alcoholic fatty liver disease (NAFLD) activity score, with significantly decreased hepatic triglyceride content (P < 0.05); Oil Red O staining confirmed reduced lipid droplet accumulation. SIL restored redox balance by increasing plasma and hepatic total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) (P < 0.05), increasing hepatic catalase (CAT) and glutathione (GSH) levels while decreasing malondialdehyde (MDA) (P < 0.05). Untargeted plasma metabolomics identified 11 key metabolites related to 2-oxoglutarate and purine metabolism, while hepatic transcriptomics revealed 835 differentially expressed genes primarily in the PPAR signaling and fatty acid biosynthesis pathways. SIL suppressed de novo lipogenesis via downregulation of ACACA and FASN, and enhanced β-oxidation through upregulation of CPT1A and ACSL1 (P < 0.05). Molecular docking and Western blotting confirmed strong SIL binding to these targets and corresponding protein changes. Correlation networks associated ACSL1 and CPT1A with improved performance and antioxidant indices, while FASN, ACACA, and xanthosine showed inverse relationships. These findings emphasize the potential of SIL as a sustainable animal nutrition antioxidant additive, which can alleviate HS induced lipid disorders in the liver of laying hens and provide insights for livestock applications.

Abstract: Model systems that mimic human cardiac structure and function are essential for the development of novel diagnostics and effective treatments for cardiovascular diseases. While non-human vertebrate models, from zebrafish to pig, remain vital to cardiovascular research, the translatability of findings to human patients is often limited. Therefore, animal experiments should be supplemented with human model systems, including human induced pluripotent stem cell-derived cells, 3D engineered constructs, and last but not least, native tissue preparations and isolated primary cardiomyocytes. However, while human myocardium remains the gold standard, human heart tissue – and particularly tissue from control hearts – remains scarce, and its use in research is generally restricted to settings where tissue has been excised from diseased or failing hearts. While it is in principle possible to use tissue from rejected non-failing donor hearts that cannot be transplanted, legal hurdles (for example in Germany) can restrict the use of non-transplanted donor organs in research. Given the challenges associated with accessing and using human tissue in biomedical research, an integrated strategy towards combining non-human vertebrate models, in silico models, and human tissue-derived models is recommended, enhancing the chances of successful research and development, and helping bridge the gap between preclinical and clinical research.

Abstract: Background: DanceSport involves intermittent high-intensity efforts that may differ between styles and partners within a dance couple. However, dance-specific relative oxygen uptake (%VO₂max) in elite Standard and Latin dancers remains insufficiently described. Objective: This study aimed to characterize relative oxygen uptake during simulated competition in elite Slovak national team dancers and to examine (i) differences between Latin and Standard styles, (ii) variability across individual dances, and (iii) sex-specific patterns. Methods: Twenty elite dancers (10 couples) were divided into Latin (n = 10) and Standard (n = 10) groups. VO₂max was determined via an incremental treadmill test. During a simulated final round, breath-by-breath gas exchange was recorded using portable spirometry. Relative oxygen uptake (%VO₂max) was calculated for each dance. Style-level differences were analyzed using a two-way ANOVA (Style × Sex), and dance-specific effects were examined using repeated-measures ANOVAs. Results: No significant differences in mean %VO₂max were observed between styles (p = .269), nor were there main effects of Sex or Style × Sex interaction (p > .05). In the Latin group, %VO₂max differed significantly between dances (p < .001), with Jive highest and Rumba lowest, without sex interaction. In the Standard group, a significant Dance × Sex interaction was observed (p < .001). Male dancers showed higher %VO₂max during Quickstep, whereas females exhibited a more uniform intensity profile. Conclu-sions: Oxygen demand in DanceSport is strongly dance-dependent. Latin dances demonstrate comparable relative intensities between sexes, whereas Standard dances show sex-specific metabolic patterns, likely reflecting distinct biomechanical roles within the partnership. These findings support dance-specific and partner-sensitive approaches to physiological monitoring and training design in elite DanceSport.