Changes In Osmolality Research Articles

Role of serum osmolarity as an indicator for neurological morbidity in children with acute central nervous illness

Acute CNS illness comprising of Acute CNS infections along with Traumatic head Injury is an important cause for significant morbidity and mortality in Pediatric Intensive Care units across the world. Osmolar changes in the blood correlate well with CNS status. Acute BM is still a meaningful, host-pathogen interaction responsible for bacterial invasion of the CNS Osmolality in children with CNS illness is a good indicator of assessing neurological Morbidity and Mortality. A complex neuroendocrine system is involved in the maintenance of sodium and water homeostasis. Bacterial Meningitis (BM) is an acute purulent infection of the meninges. It is the most common bacterial infection of the CNS& it’s the medical emergency that still has high mortality and morbidity. Blood-Brain Barrier is relatively impermeable to sodium, but water crosses freely. Variety of result in sodium dysregulation such as Traumatic Brain Injury, pyogenic meningitis, viral encephalitis, which is associated with significant Mortality and Morbidity. The objective of our study is to determine the incidence and outcome of Serum Osmolar change in children presenting with acute neurological illness. A prospective observational study was carried out between Jan 6th2020-March 6 th2020 enrolling children between ages of 1 month to 15 years, admitted to the PICU of SMCH with Acute onset neurological illness. Among 40 children, 20 children with hyponatremia have 50% of neurological deficit, Children with hypernatremia 50% had Neurological deficit, which is not statistically significant at P value0.083. Among the 40 children 40% had low Osmolality, 25% have high Osmolality& 35% had normal range, which is not statistically significant at P value 0.199

Whole-Body Imaging of Neural and Muscle Activity during Behavior in Hydra vulgaris: Effect of Osmolarity on Contraction Bursts.

The neural code relates the activity of the nervous system to the activity of the muscles to the generation of behavior. To decipher it, it would be ideal to comprehensively measure the activity of the entire nervous system and musculature in a behaving animal. As a step in this direction, we used the cnidarian Hydra vulgaris to explore how physiological and environmental conditions alter simple contractile behavior and its accompanying neural and muscle activity. We used whole-body calcium imaging of neurons and muscle cells and studied the effect of temperature, media osmolarity, nutritional state, and body size on contractile behavior. In mounted Hydra preparations, changes in temperature, nutrition state, or body size did not have a major effect on neural or muscle activity, or on contractile behavior. But changes in media osmolarity systematically altered contractile behavior and foot detachments, increasing their frequency in hypo-osmolar media solutions and decreasing it in hyperosmolar media. Similar effects were seen in ectodermal, but not in endodermal muscle. Osmolarity also bidirectionally changed the activity of contraction burst (CB) neurons, but did not affect the network of rhythmic potential (RP) neurons in the ectoderm. These findings show osmolarity-dependent changes in the activity of CB neurons and ectodermal muscle, consistent with the hypothesis that CB neurons respond to media hypo-osmolarity, activating ectodermal muscle to generate CBs. This dedicated reflex could serve as an excretory system to prevent osmotic injury. This work demonstrates the feasibility of studying an entire neuronal and muscle activity in a behaving animal.

Isolation of L-form Bacteria from Urine using Filtration Method.

Transition of bacteria to the L-form state is thought to play a possible role in immune evasion and bacterial persistence during treatment with cell wall-targeting antibiotics. However, isolation and handling of L-form bacteria is challenging, mainly due to their high sensitivity to changes in osmolarity. Here, we describe detailed protocols for the preparation of L-form medium, isolation of L-forms from urine using a filtration method, detection of L-forms in urine samples by phase contrast microscopy and induction of L-forms in vitro. The exact requirements for survival and growth of L-forms may vary from strain to strain. Therefore, the methods presented here are intended to act as basic guidelines for establishing L-form protocols within individual laboratories, rather than as precise instructions. The filtration method can lead to a reduction in the number of L-forms in a sample and should not be used for quantification. However, it is the only method used so far for effective separation of cell wall-deficient variants from their walled counterparts and for identification of bacterial strains, which are capable of L-form switching in patients with urinary tract infections. The filtration method has the potential to be adapted for the isolation of L-forms from patients with other categories of bacterial infections and from environmental samples.

The Role of Tricellulin in Epithelial Jamming and Unjamming via Segmentation of Tricellular Junctions.

Collective cellular behavior in confluent monolayers supports physiological and pathological processes of epithelial development, regeneration, and carcinogenesis. Here, the attainment of a mature and static tissue configuration or the local reactivation of cell motility involve a dynamic regulation of the junctions established between neighboring cells. Tricellular junctions (tTJs), established at vertexes where three cells meet, are ideally located to control cellular shape and coordinate multicellular movements. However, their function in epithelial tissue dynamic remains poorly defined. To investigate the role of tTJs establishment and maturation in the jamming and unjamming transitions of epithelial monolayers, a semi‐automatic image‐processing pipeline is developed and validated enabling the unbiased and spatially resolved determination of the tTJ maturity state based on the localization of fluorescent reporters. The software resolves the variation of tTJ maturity accompanying collective transitions during tissue maturation, wound healing, and upon the adaptation to osmolarity changes. Altogether, this work establishes junctional maturity at tricellular contacts as a novel biological descriptor of collective responses in epithelial monolayers.

Ion-regulation, acid/base-balance, kidney function, and effects of hypoxia in coho salmon, Oncorhynchus kisutch, after long-term acclimation to different salinities

Land-based salmon farming in closed containment recirculation aquaculture systems (RAS) is an emerging industry with the potential for reducing disease prevalence, improving production efficiency, and reducing environmental impacts compared with open net-pen aquaculture. Salinity and oxygen levels are environmental factors that have significant impacts on the physiology of fishes and possibly influence the production efficiency of fishes in aquaculture. These parameters are particularly relevant for fish production in RAS, where most water parameters can be manipulated and tightly controlled. While much is known about the specific mechanisms associated with the acute transfer between FW and SW and the reverse, little is known about the effects of long-term acclimation on ion- and acid/base-regulation, especially at intermediate salinities. We measured gas-exchange, ion-regulation, acid/base balance, and renal function in coho salmon (Oncorhynchus kisutch Walbaum, 1792) acclimated to four salinities (2.5, 5.0, 10, and 30 ppt) for over a year in RAS and investigated how animals prioritize these functions when faced with 24 h exposure to hypoxia (PO2 = 63 mmHg = 8.4 kPa = 3.76–4.48 mg l−1). We show that fish that were long-term acclimated to 30 ppt had substantially higher plasma osmolality and [Na+] than fish acclimated to lower salinities. These changes were associated with a marked reduction in blood pH at 30 ppt relative to 2.5 ppt, and we discuss a possible thermodynamic link between salinity acclimation and acid/base regulation. Further, we show that hypoxia exposure results in changes in plasma osmolality by over 80 mOsm kg−1, but only in 30 ppt water, demonstrating a salinity-dependent trade-off between gas exchange and osmoregulation. This study provides insight into the physiological state and hypoxia sensitivity of market sized salmon reared under industry-relevant conditions in RAS.

SO007OVERHYDRATION TREATMENT WITH COMBINED CRYSTALLOID AND COLLOID PD SOLUTION

Abstract Background and Aims Peritoneal dialysis (PD) fluids used colloid or crystalloid solutions to achieve ultrafiltration. Here we presented our clinical experience with the intraperitoneal (IP) use of mixed solutions (MS) (crystalloid plus colloid) to treat overhydration. Method We studied the kinetics of 4-hour single-dwell exchange using 2L MS in 3 different sessions. We analysed IP fluids and IP pressure at 0,30,60,120 and 240 min plus blood samples at 0, 120 and 240 min. MS kinetics were compared with standard 4-hour 3.86 % glucose (GS) exchange. MS composition. We modified a single-dwell exchange of 2L Icodextrin (Extraneal, Baxter®) by adding a continuous 50% glucose infusion (50g Glucose per 100mL) in an aseptic technique through infusion pump (42 ml/h) over 4 hours. Results MS exchange induced a progressive increase in IP pressure with an inverse decrease in IP sodium, without significant changes in IP glucose or osmolarity. MS exchanges were well tolerated without side effects (total 25 sessions). We did not observe any remarkable change in bloods samples during the MS exchange. The combination fluid enhanced net ultrafiltration (mean 1030 ml) compared with GS (650 ml). Although the net glucose dispensed was slightly higher with MS (79 g MS vs 77.2 g GS), similar net glucose absorption was observed (49.8 g MS vs 49.9g GS) and smaller maximum intraperitoneal glucose levels (1739 mg/dL at 120 min with MS vs 2695 mg/dL with GS at 0 min). GS induced a faster initial reduction in dialysate sodium concentration while MS maintained the sodium sieving over 4-hour dwell enhancing net ultrafiltration due to sustained IP glucose concentration. Conclusion The combination fluid could be a new strategy to enhance ultrafiltration in PD patients, leaded by colloid osmosis at the beginning of PD exchange maintained by crystalloid osmosis. Figure (A) Intraperitoneal kinetics of MIXED SOLUTION for IP sodium (Na+ PF), Osmolarity PF and intraperitoneal pressure. (B, C, D) Comparison between MIXED SOLUTIONS (black line) vs Glucose solution 3,86 % (gray line) intraperitoneal kinetcs for sodium (B), intraperitoneal pressure (C) and glucose (D).

SUN-371 Hyponatremia Correction Normalizes Bone Mineral Density and Bone Fragility in Rats

Multiple epidemiologic studies have associated chronic hyponatremia with both osteoporosis and bone fractures. Studies in experimental animals and cultured cells have demonstrated that reducing the extracellular sodium concentration ([Na+]) causes bone loss primarily by increasing osteoclast formation and bone resorbing activity. In osteoclastic cell cultures, reducing [Na+] activated biochemical and functional changes in osteoclast activity, which appear to occur by direct sodium-sensing mechanisms on osteoclasts that are independent from changes in osmolality. Whether the pathological changes in bones induced by hyponatremia can be reversed by correction of hyponatremia has not been studied. The present studies were initiated to address this question. 22-month-old F344BN F1-hybrid rats were made hyponatremic using a desmopressin continuous infusion while fed a liquid diet. After 3 months of chronic sustained hyponatremia, a cohort of the hyponatremic rats were corrected to a normal [Na+] by removal of the desmopressin minipumps and allowed to recover for 2 months. Both bone density measurements by DXA and biomechanical testing were performed on excised bones from normonatremic control rats (NN, [Na+]=145±5.6 mmol/L, n=9), chronically hyponatremic rats (HN, [Na+]=114±4.7 mmol/L, n =9) and hyponatremic corrected rats (HC, [Na+]=139±1.4 mmol/L, n =9). The results confirm that chronic hyponatremia caused significant decreases in bone mineral density (BMD, g/cm2) in the L4 vertebra (NN=0.166±0.003, HN=0.151±0.002, P=0.002) and femur (NN=0.229±0.004, HN=0.213±0.005, P=0.024). Bone fragility as measured by ultimate load to fracture (UL, Newtons) was also increased in the L5 vertebra (NN=369.8±51.1, HN=262.9±29.4, P=0.0001), but only slightly in the femur (NN=295.4±57.5, HN=286.0±35.4, P=0.682). Following correction of hyponatremia, both BMD and UL recovered after 2 months to levels not significantly different than the normonatremic controls: L4 BMD (NN=0.166±0.003, HC=0.167±0.002, NS); femur bone density (NN=0.229±0.004, HC=0.226±0.003, NS); UL in the L5 vertebra (NN=369.8±51.1, HC=384.1±63.5, NS). These results show that bone fragility parameters are adversely affected by chronic hyponatremia in addition to the previously reported decreases in BMD in rats. Consistent with the BMD results, the trabecular bone in the spine was more severely affected than the cortical bone in the femur. Our results show that much of the bone pathology of hyponatremia-induced osteoporosis can be reversed following correction of the hyponatremia without using specific antiresorptive therapy. Our findings therefore raise the possibility that correction of hyponatremia may be effective as a therapy for treatment of hyponatremia-induced osteoporosis in selected patients.

Ectoine degradation pathway in halotolerant methylotrophs.

BackgroundMicroorganisms living in saline environments are forced to regulate turgor via the synthesis of organic osmoprotective compounds. Microbial adaptation to fluctuations in external salinity includes degradation of compatible solutes. Here we have examined the biochemical pathway of degradation of the cyclic imino acid ectoine, the major osmoprotector in halotolerant methane-utilizing bacteria.MethodsThe BLAST search of the genes involved in ectoine degradation in the halotolerant methanotroph Methylotuvimicrobium alcaliphilum 20Z was performed with the reference sequences of Halomonas elongata. The genes for the key enzymes of the pathway were disrupted by insertion mutagenesis and the cellular metabolites in the methanol extracts of mutant cells were analyzed by HPLC. The doeA gene from Mm. alcaliphilum 20Z was heterologously expressed in Escherichia coli to identify the product of ectoine hydrolysis catalyzed by ectoine hydrolase DoeA.ResultsWe have shown that the halotolerant methanotroph Mm. alcaliphilum 20Z possesses the doeBDAC gene cluster coding for putative ectoine hydrolase (DoeA), Nα-acetyl-L-2,4-diaminobutyrate deacetylase (DoeB), diaminobutyrate transaminase (DoeD) and aspartate-semialdehyde dehydrogenase (DoeC). The deletion of the doeA gene resulted in accumulation of the higher level of ectoine compared to the wild type strain. Nγ-acetyl-L-2,4-diaminobutyrate (Nγ-acetyl-DAB), a substrate for ectoine synthase, was found in the cytoplasm of the wild type strain. Nα-acetyl-L-2,4-diaminobutyrate (Nα-acetyl-DAB), a substrate for the DoeB enzyme, appeared in the cells as a result of exposure of the doeB mutant to low osmotic pressure. The genes for the enzymes involved in ectoine degradation were found in all aerobic methylotrophs capable of ectoine biosynthesis. These results provide the first evidence for the in vivo operation of the ectoine degradation pathway in methanotrophs and thus expand our understanding of the regulation mechanisms of bacterial osmoadaptation.ConclusionsDuring adaptation to the changes in external osmolarity, halophilic and halotolerant methylotrophs cleave ectoine, thereby entering the carbon and nitrogen of the compatible solute to the central metabolic pathways. The biochemical route of ectoine degradation in the halotolerant methanotroph Mm. alcaliphilum 20Z is similar to that in heterotrophic halophiles. We have shown that ectoine hydrolase DoeA in this methanotroph hydrolyzes ectoine with the formation of the only isomer: Nα-acetyl-DAB. All aerobic methylotrophs capable of ectoine biosynthesis harbor the genetic determinants for ectoine degradation.

Plasma Hyperosmolality Prolongs QTc Interval and Increases Risk for Atrial Fibrillation in Traumatic Brain Injury Patients.

Introduction: Hyperosmotic therapy with mannitol is frequently used for treatment cerebral edema, and 320 mOsm/kg H2O has been recommended as a high limit for therapeutic plasma osmolality. However, plasma hyperosmolality may impair cardiac function, increasing the risk of cardiac events. The aim of this study was to analyze the relation between changes in plasma osmolality and electrocardiographic variables and cardiac arrhythmia in patients treated for isolated traumatic brain injury (iTBI). Methods: Adult iTBI patients requiring mannitol infusion following cerebral edema, and with a Glasgow Coma Score below 8, were included. Plasma osmolality was measured with Osmometr 800 CLG. Spatial QRS-T angle (spQRS-T), corrected QT interval (QTc) and STJ segment were calculated from digital resting 12-lead ECGs and analyzed in relation to four levels of plasma osmolality: (A) <280 mOsm/kg H2O; (B) 280–295 mOsm/kg H2O; (C) 295–310 mOsm/kg H2O; and (D) >310 mOsm/kg H2O. All parameters were measured during five consecutive days of treatment. Results: 94 patients aged 18-64 were studied. Increased plasma osmolality correlated with prolonged QTc (p < 0.001), intensified disorders in STJ and increased the risk for cardiac arrhythmia. Moreover, plasma osmolality >313 mOms/kg H2O significantly increased the risk of QTc prolongation >500 ms. Conclusion: In patients treated for iTBI, excessively increased plasma osmolality contributes to electrocardiographic disorders including prolonged QTc, while also correlating with increased risk for cardiac arrhythmias.

Impact of Nutrient Intake on Hydration Biomarkers Following Exercise and Rehydration Using a Clustering-Based Approach.

We investigated the impact of nutrient intake on hydration biomarkers in cyclists before and after a 161 km ride, including one hour after a 650 mL water bolus consumed post-ride. To control for multicollinearity, we chose a clustering-based, machine learning statistical approach. Five hydration biomarkers (urine color, urine specific gravity, plasma osmolality, plasma copeptin, and body mass change) were configured as raw- and percent change. Linear regressions were used to test for associations between hydration markers and eight predictor terms derived from 19 nutrients merged into a reduced-dimensionality dataset through serial k-means clustering. Most predictor groups showed significant association with at least one hydration biomarker: (1) Glycemic Load + Carbohydrates + Sodium, (2) Protein + Fat + Zinc, (3) Magnesium + Calcium, (4) Pinitol, (5) Caffeine, (6) Fiber + Betaine, and (7) Water; potassium + three polyols, and mannitol + sorbitol showed no significant associations with any hydration biomarker. All five hydration biomarkers were associated with at least one nutrient predictor in at least one configuration. We conclude that in a real-life scenario, some nutrients may serve as mediators of body water, and urine-specific hydration biomarkers may be more responsive to nutrient intake than measures derived from plasma or body mass.

Importance of Transient Receptor Potential Channels of the Ocular Surface: Insights and Outlook - from Laboratory Research to Clinical Practice

Optimal vision requires an ocular surface with vital epithelial coverage and a stable tear film. A multitude of endogenous and external factors may alter this delicate balance. Studies over the last decade have established that Ca2+ is an important factor in the control of ocular surface epithelial function and has led to the identification of critical components. In particular, transient receptor potential channels (TRPs) have been identified as important components in corneal and conjunctival cells. These channels encompass a group of ion channels of numerous cell types. TRPs are nonselective cation channels which are Ca2+ permeable. Most TRPs serve as thermosensitive molecular sensors (thermo-TRPs). Our Ca2+ imaging and patch-clamp studies indicate that the activity of two TRP isoforms, TRPV1 and TRPM8, can be modulated by changes in external temperature osmolarity and some endogenous substrates. These TRPs are expressed on both non-neuronal and neuronal corneal cells. Furthermore, these interactions affect control of cytokines either promoting or inhibiting inflammation, one of the key findings in dry eye syndrome. Taken together, these results not only lead to a better understanding of the pathophysiology in pain and inflammation reactions on the surface of the eye, but these studies may also offer new avenues to understand the pathophysiology of the disease and support the development of novel therapeutic targets in dry eye syndrome.

Dry Eye and Dry Nose Caused by the Effect of Allergic Rhinitis on Tear and Nasal Secretion Osmolarity.

Allergic rhinitis is a type 1 hypersensitivity reaction of immunoglobulin E in the rhino-ocular mucosa. This study was planned to demonstrate in patients with allergic rhinitis to evaluate changes in tear, nasal secretions, and blood osmolarity compared to healthy individuals. Forty allergic rhinitis patients, 25 patients with acute upper respiratory tract infections, and 26 healthy participants were included in the study. Positive patients with allergic symptoms and skin prick test results were included in the allergic rhinitis group. Tear, nasal secretion, and blood osmolarity values were examined for the 3 groups. In patients with allergic rhinitis, tear and nasal secretion osmolarity values were significantly higher in patients with acute upper respiratory tract infections and those of the healthy participants (P = .001, P = .038). In blood osmolarity measurements, there was no statistical difference between the groups (P = .489). In patients with allergic rhinitis, Schirmer test results were significantly shorter than patients who had acute upper respiratory tract infection and those of the healthy participants (P = .001, P = .001). Patients with allergic rhinitis and acute upper respiratory tract infections had significantly shorter Schirmer test results than in healthy participants (P = .001, P = .001). Tear osmolarity was increased in allergic rhinitis patients, and this was thought to lead to dry eye findings. In the presence of allergic rhinitis, nasal secretions were found more hyperosmolar than tears. Nasal secretion osmolarity was higher in allergic rhinitis patients than in patients with acute upper respiratory tract infections and control group.

Hypernatremia

Hypernatremia is acommon electrolyte disorder in daily clinical practice. In many cases hypernatremia is caused by alack of free water or an increased salt load. Out-of-hospital acquired hypernatremia is often caused by an increased loss of water or adecreased water intake. By contrast, hospital-acquired, nosocomial hypernatremia is often induced by an inadequate fluid balance with saline infusions, saline overload, or due to osmotic diuresis. The consequences are structural changes in the cell morphology such as cell shrinkage. Chronic hypernatremia affects all cell functions predominantly with cerebral symptoms and coma; the main complication is atoo-rapid compensation of an adapted electrolyte imbalance with development of cerebral edema. The overall osmolality should always be considered. Overall changes in osmolality correspond to the effect on the cellular stress situation and have to be taken into account and balanced slowly. In cases of unknown duration, achronic disorder should be assumed.

Genome-wide analysis of MicroRNA-messenger RNA interactome in ex-vivo gill filaments, Anguilla japonica

BackgroundGills of euryhaline fishes possess great physiological and structural plasticity to adapt to large changes in external osmolality and to participate in ion uptake/excretion, which is essential for the re-establishment of fluid and electrolyte homeostasis. The osmoregulatory plasticity of gills provides an excellent model to study the role of microRNAs (miRs) in adaptive osmotic responses. The present study is to characterize an ex-vivo gill filament culture and using omics approach, to decipher the interaction between tonicity-responsive miRs and gene targets, in orchestrating the osmotic stress-induced responses.ResultsEx-vivo gill filament culture was exposed to Leibovitz’s L-15 medium (300 mOsmol l− 1) or the medium with an adjusted osmolality of 600 mOsmol l− 1 for 4, 8 and 24 h. Hypertonic responsive genes, including osmotic stress transcriptional factor, Na+/Cl−-taurine transporter, Na+/H+ exchange regulatory cofactor, cystic fibrosis transmembrane regulator, inward rectifying K+ channel, Na+/K+-ATPase, and calcium-transporting ATPase were significantly upregulated, while the hypo-osmotic gene, V-type proton ATPase was downregulated. The data illustrated that the ex-vivo gill filament culture exhibited distinctive responses to hyperosmotic challenge. In the hyperosmotic treatment, four key factors (i.e. drosha RNase III endonuclease, exportin-5, dicer ribonuclease III and argonaute-2) involved in miR biogenesis were dysregulated (P < 0.05). Transcriptome and miR-sequencing of gill filament samples at 4 and 8 h were conducted and two downregulated miRs, miR-29b-3p and miR-200b-3p were identified. An inhibition of miR-29b-3p and miR-200b-3p in primary gill cell culture led to an upregulation of 100 and 93 gene transcripts, respectively. Commonly upregulated gene transcripts from the hyperosmotic experiments and miR-inhibition studies, were overlaid, in which two miR-29b-3p target-genes [Krueppel-like factor 4 (klf4), Homeobox protein Meis2] and one miR-200b-3p target-gene (slc17a5) were identified. Integrated miR-mRNA-omics analysis revealed the specific binding of miR-29b-3p on Klf4 and miR-200b-3p on slc17a5. The target-genes are known to regulate differentiation of gill ionocytes and cellular osmolality.ConclusionsIn this study, we have characterized the hypo-osmoregulatory responses and unraveled the modulation of miR-biogenesis factors/the dysregulation of miRs, using ex-vivo gill filament culture. MicroRNA-messenger RNA interactome analysis of miR-29b-3p and miR-200b-3p revealed the gene targets are essential for osmotic stress responses.

A 12-month Prospective Study of Tear Osmolarity in Contact Lens Wearers Refitted with Daily Disposable Soft Contact Lenses.

Tear osmolarity has been reported as one of the best diagnostic tests for dry eye disease and its management. Contact lens wear is thought to influence tear homeostasis. Understanding how regular wear of contact lenses and their type affect tear osmolarity is important. The purpose of this study was to assess changes in tear osmolarity and ocular symptoms over a period of 12 months following refitting contact lens wearers with daily disposable contact lenses. Fifty subjects aged (mean ± SD) 26 ± 4 years were refitted with either silicone-hydrogel (delefilcon A, SiHy, n = 34) or hydrogel (omafilcon A, Hy, n = 16) daily disposable soft contact lenses. Study included seven visits: baseline measurements without contact lenses; two visits for contact lens fit and selection; follow-up measurements after 3, 6, and 12 months of contact lens wear; and a post-study visit without contact lenses. Lens type selection was based on a set of objective measurements. Subjects were instructed to follow strict wearing rules. Impedance-based osmometer was used to collect samples from the lower tear meniscuses. The Ocular Surface Disease Index (OSDI) and the eight-item Contact Lens Dry Eye Questionnaire were used to assess subject-reported ocular symptoms and contact lens discomfort, respectively. Downward trend of tear osmolarity was noted over the time course of study. Statistically significant differences were noted in tear osmolarity (Friedman test, χ = 21.91 [P < .001], and χ = 13.89 [P = .003]) for the right and left eyes, respectively. A statistically significant decrease in tear osmolarity was apparent only for initially symptomatic subjects (for OSDI ≥13: χ = 26.25, P < .001; for OSDI <13: χ = 5.65, P = .13). Statistically significant differences were not noted in OSDI and the eight-item Contact Lens Dry Eye Questionnaire between the baseline and 12-month visit (χ = 5.92 [P = .12] and R = 0.015 [P = .87], respectively). There was a difference between baseline and post-study visits (P = .002) in OSDI, showing lower score at the latter visit. Refitting with daily disposable contact lenses was demonstrated to lower tear osmolarity.

Positional alcohol nystagmus and serum osmolality: New insights into dizziness associated with acute alcohol intoxication

Positional alcohol nystagmus (PAN) is characterized by positional direction-changing nystagmus. Although the buoyancy cupulopathy, which implies that the cupula becomes lighter or heavier than the endolymph due to different diffusion rates of alcohol, has been accepted as possible mechanism of PAN, the evidence supporting this hypothesis is weak. The aim of present study is to investigate the possibility of serum osmolality change following alcohol intake as a cause of PAN. Nine healthy adults were recruited voluntarily. Positional nystagmus was examined before and every 1 hr after alcohol intake until 7 hr. Serum osmolality was measured before and 1 and 7 hr after alcohol intake. Before ingesting alcohol, no subject showed positional nystagmus, and mean serum osmolality was 285.9 ± 4.4 mOsm/kg. At 1 hr after drinking, mean serum osmolality increased to 302.9 ± 8.9 mOsm/kg, and all subjects exhibited geotropic positional nystagmus. At 7 hr after drinking, mean serum osmolality decreased to 289.1 ± 9.4 mOsm/kg, and all subjects showed ageotropic positional nystagmus. Change in serum osmolality following alcohol ingestion and subsequent change in specific gravity in the perilymph and endolymph may be a cause of PAN.

Elevated TRPV4 Levels Contribute to Endothelial Damage and Scarring in Experimental Spinal Cord Injury.

Currently, the role of transient receptor potential vanilloid type 4 (TRPV4), a nonselective cation channel in the pathology of spinal cord injury (SCI), is not recognized. Herein, we report the expression and contribution of TRPV4 in the pathology of scarring and endothelial and secondary damage after SCI. TRPV4 expression increased during the inflammatory phase in female rats after SCI and was expressed primarily by cells at endothelial-microglial junctions. Two-photon microscopy of intracellular-free Ca2+ levels revealed a biphasic increase at similar time points after SCI. Expression of TRPV4 at the injury epicenter, but not intracellular-free Ca2+, progressively increases with the severity of the injury. Activation of TRPV4 with specific agonist altered the organization of endothelial cells, affected tight junctions in the hCMEC/D3 BBB cell line in vitro, and increases the scarring in rat spinal cord as well as induced endothelial damage. By contrast, suppression of TRPV4 with a specific antagonist or in female Trpv4 KO mouse attenuated inflammatory cytokines and chemokines, prevented the degradation of tight junction proteins, and preserve blood-spinal cord barrier integrity, thereby attenuate the scarring after SCI. Likewise, secondary damage was reduced, and behavioral outcomes were improved in Trpv4 KO mice after SCI. These results suggest that increased TRPV4 expression disrupts endothelial cell organization during the early inflammatory phase of SCI, resulting in tissue damage, vascular destabilization, blood-spinal cord barrier breakdown, and scarring. Thus, TRPV4 inhibition/knockdown represents a promising therapeutic strategy to stabilize/protect endothelial cells, attenuate nociception and secondary damage, and reduce scarring after SCI.SIGNIFICANCE STATEMENT TRPV4, a calcium-permeable nonselective cation channel, is widely expressed in both excitable and nonexcitable cells. Spinal cord injury (SCI) majorly caused by trauma/accidents is associated with changes in osmolarity, mechanical injury, and shear stress. After SCI, TRPV4 was increased and were found to be linked with the severity of injury at the epicenter at the time points that were reported to be critical for repair/treatment. Activation of TRPV4 was damaging to endothelial cells that form the blood-spinal cord barrier and thus contributes to scarring (glial and fibrotic). Importantly, inhibition/knockdown of TRPV4 prevented these effects. Thus, the manipulation of TRPV4 signaling might lead to new therapeutic strategies or combinatorial therapies to protect endothelial cells and enhance repair after SCI.

Autophagy and Hsp70 activation alleviate oral epithelial cell death induced by food-derived hypertonicity.

Stable intracellular and intercellular osmolarity is vital for all physiological processes. Although it is the first organ that receives food, the osmolarity around the mouth epithelium has never been systematically investigated. We found that oral epithelial cells are a population of ignored cells routinely exposed to hypertonic environments mainly composed of saline, glucose, etc. in vivo after chewing food. By using cultured oral epithelial cells as an in vitro model, we found that the hypotonic environments caused by both high NaCl and high glucose induced cell death in a dose- and time-dependent manner. Transcriptomics revealed similar expression profiles after high NaCl and high glucose stimulation. Most of the common differentially expressed genes were enriched in "mitophagy" and "autophagy" according to KEGG pathway enrichment analysis. Hypertonic stimulation for 1 to 6h resulted in autophagosome formation. The activation of autophagy protected cells from high osmolarity-induced cell death. The activation of Hsp70 by the pharmacological activator handelin significantly improved the cell survival rate after hypertonic stimulation. The protective role of Hsp70 activation was partially dependent on autophagy activation, indicating a crosstalk between Hsp70 and autophagy in hypertonic stress response. The extract of the handelin-containing herb Chrysanthemum indicum significantly protected oral epithelial cells from hypertonic-induced death, providing an inexpensive way to protect against hypertonic-induced oral epithelial damage. In conclusion, the present study emphasized the importance of changes in osmolarity in oral health for the first time. The identification of novel compounds or herbal plant extracts that can activate autophagy or HSPs may contribute to oral health and the food industry.

The Uptake and Release of Amino Acids by Staphylococcus aureus at Mid-Exponential and Stationary Phases and Their Corresponding Responses to Changes in Temperature, pH and Osmolality.

Staphylococcus aureus is an important pathogen that is associated with nosocomial infections, as well as food poisoning. This bacterium is resistant to antimicrobial agents and can survive in a wide range of environmental conditions. The aim of this study was to measure the uptake and release of amino acids by S. aureus at mid-exponential and stationary phases of growth following exposure to a combination of conditions including variations in temperature, pH and NaCl. Bacterial cells were grown up to mid-exponential and stationary phases in tryptic soy broth (TSB), where the supernatants were collected for analyses of amino acids to determine the uptake and release characteristics. The uptake/release of amino acids was estimated by subtracting the initial levels of the free amino acids in the media from those measured at mid-exponential and stationary phases of growth. When cells were grown at ideal conditions, the analyses revealed that significant uptake of amino acids had occurred by stationary phase compared with the mid-exponential phase. A substantial release of valine and tyrosine into the external media was observed by cells at stationary phase. At both phases, the uptake and release patterns were significantly different between cells grown under ideal control conditions, when compared with those grown under various combinations of sub-optimal environmental conditions. The analyses of the supernatants harvested from controls and treatment groups at exponential phase indicated that the total uptake of amino acids was reduced approximately five times by cells grown with addition of 2.5% NaCl or with pH6 at 35°C, and 2-fold by cells grown at pH8 at 35°C. However, the final quantities of amino acids taken up by cells grown to stationary phase did not significantly alter between control and treated samples. Valine was found to be the most abundant amino acid that was significantly released into the media at stationary phase by both control and treated samples. It was evident that diverse environmental conditions resulted in differential patterns of amino acid uptake and release during adaptation to designated conditions.

Structural basis for osmotic regulation of the DNA binding properties of H-NS proteins.

H-NS proteins act as osmotic sensors translating changes in osmolarity into altered DNA binding properties, thus, regulating enterobacterial genome organization and genes transcription. The molecular mechanism underlying the switching process and its conservation among H-NS family members remains elusive. Here, we focus on the H-NS family protein MvaT from Pseudomonas aeruginosa and demonstrate experimentally that its protomer exists in two different conformations, corresponding to two different functional states. In the half-opened state (dominant at low salt) the protein forms filaments along DNA, in the fully opened state (dominant at high salt) the protein bridges DNA. This switching is a direct effect of ionic strength on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of MvaT. The asymmetric charge distribution and intramolecular interactions are conserved among the H-NS family of proteins. Therefore, our study establishes a general paradigm for the molecular mechanistic basis of the osmosensitivity of H-NS proteins.