Sepsis is an inflammatory disorder caused by the host’s dysfunctional response to infection. Septic patients present diverse clinical characteristics, and in the recent years it has been the main cause of death in intensive care units (ICU). Aquaporins, membrane proteins with role in water transportation, have been reported to participate in numerous biological processes. Their role in sepsis progression has been studied extensively. This review aims to examine recent literature on aquaporin expression and regulation in clinical sepsis, as well as established experimental models of sepsis. We will present how sepsis affects aquaporin expression at the molecular and protein level. Moreover, we will delve into the importance of aquaporin regulation at the transcriptional, post-transcriptional, translational, and post-translational level in sepsis, by presenting data on aquaporin regulation by non-coding RNAs and selected chemical molecules. Finally, we will focus on the importance of aquaporin single nucleotide polymorphisms in the setting of sepsis.

In flowering plants with dry stigmas, pollen hydration involves water movement, which may be facilitated by aquaporins. To explore the possibility underlying this biological process, we identified and characterized a mutant with a T-DNA insertion in PIP2;5, which encodes an aquaporin with water channel activity in the PIP2 subfamily. We monitored the pollination process (pollen hydration, germination, and pollen tube growth) of wild type pollen on stigmas of the mutant and wild type. Pollen hydration was postponed on the stigmas of the mutant, compared with that on wild type stigmas. However, pollen tube germination and growth was unaffected in the mutant. The PIP2;5 protein was located in the cell plasma membrane and was preferentially expressed in the stigma. Based on our results, we concluded that PIP2;5 might play an important role in water movement during pollen hydration.

There is an urgent need to better understand the mechanisms involved in scar formation in brain. It is well known that astrocytes are critically engaged in this process. Here we analyze in-cipient scar formation one week after a discrete ischemic insult to the cerebral cortex. We show that the infarct border zone is characterized by pronounced changes in the organization and subcellular localization of the major astrocytic protein AQP4. Specifically there is a loss of AQP4 from astrocytic endfoot membranes that anchor astrocytes to pericapillary basal laminae and a disassembly of the supramolecular AQP4 complexes that normally abound in these membranes. This disassembly may be mechanistically coupled to a downregulation of the newly discovered AQP4 isoform AQP4ex. AQP4 has adhesive properties and is assumed to facilitate astrocyte mo-bility by permitting rapid volume changes at the leading edges of migrating astrocytes. Thus, the present findings provide new insight in the molecular basis of incipient scar formation.

The theory of water transport in trees, according to which the main driving force of water movement is the suction created by the evaporation of water by the meniscus (the curved surface of the capillary liquid column) on the evaporating elements, supported from below by root pressure, is flawed. The capillary effect in nature is around one meter. In the case of open-air gaps, the leaf cannot suck in the water against gravity because, in this case, the plant would not be sucking in water, but air through the open-air gap. If not, how do trees transport water? When evaporation occurs, there is no suction towards the canopy, but pressure is due to a reduction in the cross-section of the water pipe caused by heat loss through evaporation. At night, when evaporation stops, a thermal equilibration process is triggered, which restores the original cross-section of the pipe. This generates suction and draws water from the soil. As the hydrostatic pressure in the pipe is high for tall trees, the pipe is cut off. To prove my theory, I have given several examples. Water transport is not based on physical mechanical laws alone. There may be complex physiological, biochemical, and biophysical processes behind the operation of the pipe system.

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a rare immune-mediated relapsing-remitting disease of the central nervous system. The usage of rituximab, to prevent NMOSD relapses, is common in Sweden, but the knowledge on long-term efficacy and risk for severe infections are limited. We performed a retrospective cohort study with medical chart review of rituximab-treated NMOSD patients at the Karolinska University Hospital, Sweden, to assess the occurrence of relapses and severe infectious events (SIE). Furthermore, we collected data on CD19+ lymphocyte, and IgG levels during therapy. A total of 42 NMOSD patients; 24 with aquaporin -4 antibodies (AQP4+), eight with myelin oligodendrocyte glycoprotein antibodies (MOG+) and 10 with absence of antibodies (double-seronegative) were included. During a mean treatment time of 4.4 years, 37% AQP4+, 75% MOG+, and 60% double-seronegative patients experienced 1 relapse. SIEs were common with 46% of AQP4+, 25% of MOG+, and 40% of double-seronegative patients affected. Incomplete CD19+ lymphocyte suppression did not predict a relapse and there was no correlation between IgG levels and SIEs. In conclusion, our data demonstrated a high risk for both relapses and SIEs in rituximab-treated NMOSD patients highlighting the need for close clinical vigilance of disease activity and infections during treatment.

With the advent of real-time MRI, the motion and passage of cerebrospinal fluid can be visualized without gating and exclusion of low-frequency waves. This imaging modality gives insights into low-volume, rapidly oscillating cardiac-driven movement as well as sustained, high-volume, slowly oscillating inspiration-driven movement.Inspiration means a spontaneous or artificial increase in the intrathoracic dimensions independent of body position. Alterations in thoracic diameter enable the thoracic and spinal epidural venous compartments to be emptied and filled, producing an upward surge of cerebrospinal fluid inside the spine during inspiration; this surge counterbalances the downward pooling of venous blood toward the heart.Real-time MRI, as a macroscale in vivo observation method, could expand our knowledge of neurofluid dynamics, including how astrocytic fluid preloading is adjusted and how brain buoyancy and turgor are maintained in different postures and zero gravity.Along with these macroscale findings, new microscale insights into aquaporin-mediated fluid transfer, its sensing by cilia and its tuning by nitric oxide will be reviewed. By incorporating clinical knowledge spanning several disciplines, certain disorders—congenital hydrocephalus with Chiari malformation, idiopathic intracranial hypertension and adult idiopathic hydrocephalus—are interpreted and reviewed according to current concepts, from the basics of the interrelated systems to their pathology.

New experimental and clinical findings question the historic view of hydrocephalus and its 100-year-old classification. In particular, real-time MRI evaluation of CSF flow and detailed insights into brain water regulation on the molecular scale indicate the existence of at least three main mechanisms that determine the dynamics of neurofluids. (i) Inspiration is a major driving force (ii) Adequate filling of brain ventricles by balanced cerebrospinal fluid upsurge is sensed by cilia (iii) The perivascular glial network connects the ependymal surface to the pericapillary Virchow-Robin spaces. Hitherto, these aspects have not been considered a common physiologic framework improving knowledge and therapy for severe disorders of normal-pressure and post-haemorrhagic hydrocephalus, spontaneous intracranial hypotension and spaceflight disease.

Neuromyelitis optica spectrum disorder (NMOSD), previously known as Devic disease or neuromyelitis optica (NMO), represents inflammatory conditions affecting the central nervous system. These disorders are characterized by severe immune-mediated demyelination and axonal damage, with a predilection for targeting optic nerves and the spinal cord. Key clinical features of NMOSD encompass acute episodes of bilateral or rapid sequential optic neuritis and transverse myelitis, typically exhibiting a relapsing course. These attacks endure for several days, and recovery varies, spanning from weeks to months. In this report, we present the case of a 35-year-old individual who initially complained of urinary retention, followed by decreasing vision in the left eye and subsequently in the right eye. These visual symptoms were succeeded by weakness in the right upper and lower limbs.

Various attempts to amplify an AQP11 cDNA from tissues of the spiny dogfish (Squalus acanthias) were made. Two pairs of deoxy-inosine-containing degenerate primers were designed based on conserved amino acid sequences from an AQP11 alignment. These primers yielded some faint bands from gill cDNA that were sequenced. Blast searches with the sequences showed they were not AQP11. An elasmobranch AQP11 nucleotide sequence alignment was produced to identify conserved regions to make further degenerate primers. One primer pair produced a short 148bp fragment showing particularly strong expression in gill and intestine. It was sequenced and represented a piece of the AQP11 gene. However, as the fragment may have resulted from contaminating genomic DNA (in total RNA used to make cDNA), 5’ and 3’ RACE was performed to amplify the two ends of the putative cDNA. 5’ and 3’ RACE amplifications depend on the presence of a 5’ cap nucleotide and a poly A tail respectively on the putative AQP11 mRNA. Hence successful amplification was only possible from cDNA and not genomic DNA. Nested RACE amplifications were performed using gill and intestinal RACE cDNA but none of the DNA fragments were AQP11. Consequently, the spiny dogfish AQP11 gene may represent a pseudogene.