Fluid Regulation Research Articles

Efficacy of Tolvaptan in Older Adults Undergoing Cardiac Surgery: A Single-Center Retrospective Analysis.

Globally, cardiovascular diseases remain a predominant cause of mortality. Effective fluid management is particularly critical in older adults undergoing cardiac surgery, due to their heightened risk of postoperative complications. Tolvaptan, an oral vasopressin V2 receptor antagonist, has emerged as a promising agent for fluid regulation in cardiac patients. However, its efficacy in the elderly undergoing cardiac surgery is not thoroughly evaluated. This single-center retrospective analysis included 146 older adults (≥ 65 years) who underwent cardiac surgery between January 2018 and December 2022. Patients were categorized into two groups: those receiving tolvaptan and a control group receiving traditional diuretics post-surgery. We assessed several outcomes, including hospital length of stay, 30-day mortality, postoperative renal function, and complications. The study found a significantly reduced hospitalization duration in the tolvaptan group (P=0.044), with no escalation in adverse events. The tolvaptan cohort exhibited a considerable increase in urine output on the postoperative day (POD) three (P=0.003), indicating enhanced renal function and fluid management. Serum creatinine levels notably declined by POD3 (P=0.012), and blood urea nitrogen levels were appreciably lower by POD5 (P<0.001) in the tolvaptan group. Furthermore, serum sodium levels significantly escalated on POD3 and POD5 (P<0.01) in this group, while serum potassium levels remained unchanged. Tolvaptan significantly optimizes postoperative fluid management in older adults undergoing cardiac surgery. Its administration is linked to improved renal function and a shortened hospital stay, without amplifying adverse effects. These insights could enhance clinical practices and facilitate the management of fluid overload in this vulnerable demographic.

Impact of Renin-angiotensin system inhibitors on response to PD1/L1 inhibitors in patients with Metastatic Renal Cell Carcinoma

BackgroundThe renin-angiotensin-aldosterone system (RAAS), traditionally associated with blood pressure and fluid regulation, also plays a role in tumorigenesis. Renin-angiotensin-aldosterone system inhibitors (RAASI), including angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARBs), have been shown to improve outcomes in various malignant neoplasms. In metastatic urothelial cancer, the use of RAASI have been associated with higher rates of tumor regression in patients receiving immunotherapy (IO) with PD1/L1 inhibitors. This is thought to be due to RAASI-induced downregulation of TGF-beta, for which increased expression is a known mechanism of PD1/L1 inhibitor resistance. We hypothesized that concurrent RAASI in patients with mRCC receiving IO is associated with increased tumor regression. MethodsWe conducted a retrospective analysis of patients with mRCC receiving IO as a first- or second-line therapy from 2016-2023 at the University of Virginia. A logistic regression model was used to evaluate the impact of concurrent RAASI on tumor regression. The primary endpoint was any regression of tumor on imaging. ResultsData were available for 128 patients with mRCC who received IO as a first- (n=91, 71.0%) or second- (n=37, 28.9%) line treatment. Patients who received RAASI during IO were more likely to have tumor regression compared to patients who were not on concurrent RAASI (OR 3.84 [95% CI 1.81-8.47, p=<0.001). This held true regardless if patients received IO as a first-line (OR 2.83 [95% CI 1.2-6.94], p=0.0173) or second-line (OR 9.5 [95% CI 1.89-73.1], p=0.005) treatment. ConclusionsOur hypothesis generating study suggests that in our mRCC population, concurrent use of RAASI in patients receiving IO was associated with a significantly increased likelihood of tumor regression. These findings highlight the potential therapeutic advantage of RAASI in combination with IO for mRCC patients. Further exploration of this association is warranted in prospective studies to improve treatment outcomes for this patient population. MicroAbstractRenin-angiotensin-aldosterone system inhibitors (RAASI) have been shown to improve outcomes in various malignancies. In this retrospective, single-center study, we found that concurrent use of RAASI in patients with mRCC receiving IO is associated with a significantly increased likelihood of tumor regression. Our findings suggest the potential therapeutic advantage of RAASI in combination with IO for mRCC patients.

Nursing Care for Septic Shock Patients Using Indonesian Nursing Standards: A Case Reports

Aims: This case report aimed to identify gaps in applying the Nursing Standard Guidelines of the Indonesian Association in critical care, specifically focusing on patients with septic shock. Methods: This study used a case report with a nursing care approach that includes an assessment to evaluation. Nursing care was provided to a patient who was experiencing septic shock, was on a ventilator, and had experienced organ failure. Results: A 63-year-old man on mechanical ventilator was diagnosed with septic shock caused by community-acquired pneumonia. The nursing diagnoses for this case included impaired spontaneous ventilation related to respiratory muscle weakness, ineffective airway clearance related to the accumulation of secretions, peripheral tissue perfusion disorders related to changes in fluid regulation, and risk of infection. The study identified inappropriate nursing diagnoses, such as 'impaired spontaneous ventilation for patients on mechanical ventilation. Conclusion: This study concludes that there are still several gaps in diagnosing and managing clinical conditions in critical cases. The nursing problem of impaired spontaneous ventilation should not have been identified as the patient was already on a ventilator. Additionally, there was no actual diagnosis for impaired organ perfusion or infection. This case report recommends further developing the Nursing Standard Guidelines of the Indonesian Nursing Association to optimize coverage of critical care. Recommendations include revising the Indonesian Nursing Diagnosis Standards to align with critical care needs. This enhancement will help nurses and clinicians in critical care not experience confusion when applying the current guidelines.

The GTPase RAB6 is required for stem cell maintenance and cell migration in the gut epithelium.

Intestinal epithelial cells, which are instrumental in nutrient absorption, fluid regulation, and pathogen defense, undergo continuous proliferation and differentiation within the intestinal crypts, migrating towards the luminal surface where they are eventually shed. RAB GTPases are key regulators of intracellular vesicular trafficking and are involved in various cellular processes, including cell migration and polarity. Here, we investigated the role of RAB6 in the development and maintenance of the gut epithelium. We generated conditional knockout mice with RAB6 specifically deleted in the gut epithelium. We found that deletion of the Rab6a gene resulted in embryonic lethality. In adult mice, RAB6 depletion led to altered villus architecture and impaired junction integrity without affecting the segregation of apical and basolateral membrane domains. Further, RAB6 depletion slowed down cell migration and adversely affected both cell proliferation and stem cell maintenance. Notably, the absence of RAB6 resulted in a diminished number of functional stem cells, as evidenced by the rapid death of isolated crypts from Rab6a KO mice when cultured as 3D organoids. Together, these results underscore the essential role of RAB6 in maintaining gut epithelial homeostasis.

NH4Cl-induced metabolic acidosis increases the abundance of HCO3 - transporters in the choroid plexus of mice.

Regulation of cerebrospinal fluid (CSF) pH and brain pH are vital for all brain cells. The acute regulation of CSF pH is dependent on the transport of HCO3 - across the choroid plexus in the brain ventricles. Acute regulation in response to acidosis is dependent on H+ export and HCO3 - import across the plasma membrane. Acute regulation in response to alkalosis is dependent on HCO3 - export across the plasma membrane. The objective of the study was to investigate the contribution of the Na+-dependent HCO3 - transporters, Ncbe, NBCn1, and NBCe2 to CSF pH regulation during chronic metabolic acidosis in mice. To induce metabolic acidosis, mice received 0.28 M ammonium chloride (NH4Cl) in the drinking water for three, five, or seven days. While in vivo, CSF pH measurements did not differ, measurements of CSF [HCO3 -] revealed a significantly lower CSF [HCO3 -] after three days of acid-loading. Immunoblotting of choroid plexus protein samples showed that the abundance of the basolateral Na+/HCO3 - transporter, NBCn1, was significantly increased. This was followed by a significant increase in CSF secretion rate determined by ventriculo-cisternal perfusion. After five days of treatment with NH4Cl, CSF [HCO3 -] levels were normalized. After the normalization of CSF [HCO3 -], CSF secretion was no longer increased but the abundance of the basolateral Na+-dependent HCO3 - transporters Ncbe and NBCn1 increased. The luminal HCO3 - transporter, NBCe2, was unaffected by the treatment. In conclusion, we establish that 1) acidotic conditions increase the abundance of the basolateral Na+-dependent HCO3 - transporters in the choroid plexus, 2) NH4Cl loading in mice lowers CSF [HCO3 -] and 3) leads to increased CSF secretion likely caused by the increased capacity for transepithelial transport of Na+ and HCO3 - in the choroid plexus.

Abstract P422: Neuropeptide FF and Its Receptor NPFFR2 Decrease Renal Sodium Excretion and Increase Blood Pressure in Mice

The kidney is critical in the overall regulation of fluid and electrolyte balance and blood pressure. Neuropeptide FF (NPFF), a morphine-modulating peptide, regulates cardiovascular function through its interaction with two receptors, NPFFR1 and NPFFR2. We now report that NPFF and its receptors, mainly NPFFR2, are expressed in the kidney. NPFF (9.25 mmol, 0.5 mL/hr, 0.05 nmol/day, 7 days) chronically infused underneath the renal capsule, decreased renal sodium excretion (UNaV) from 0.68±0.07 mEq/day, n=5 to 0.43±0.06 mEq/day (n=6/group) in conscious C57BL/6 mice. This was accompanied by an increase in systolic blood pressure (SBP, 114.5±5.0 mm Hg, n=4); the infusion of vehicle (saline) did not affect the blood pressure (96.4±3.0 mm Hg, n=4). The renal subcapsular injection of a single dose (10 µg in 100 µL) of NPFF also increased SBP within 15-35 min (NPFF: 105.5±3.44 mm Hg, n=6); saline injection did not affect SBP (82.6±5.65 mm Hg, n=4). RF-9 (10 µg in 100 µL), an antagonist of NPFF receptors prevented the NPFF-mediated increase in SBP (NPFF alone: 105.5±3.44 mm Hg, n=6; RF+NPFF: 88.5±5.90 mm Hg, n=5), whereas RF-9, alone, had no effect (Baseline: 97.6±2.70 mmHg; RF-9: 90.9±4.70 mm Hg, n=5). The renal subcapsular injection of scrambled peptide (10 µg in 100 µL) had no effect on SBP (86.1±1.83 mm Hg, n=4). However, SBP was decreased by the renal subcapsular infusion of Npffr2 siRNA (98±4 vs 113±3 mmHg; P &lt; 0.05; n=3-5/group) in C57Bl/6 mice fed with a high salt diet (4% NaCl). Furthermore, the SBP of conventional germline Npffr2 knockout (KO) mice fed a high salt (4% NaCl) diet was lower than the SBP of wild-type (WT) littermates (WT: 105.6±2.9 mm Hg, n=5; KO: 90.5±5.5 mm Hg, n=4, P &lt; 0.05). By contrast, in mice fed normal salt (0.8% NaCl) diet, SBP was not different between Npffr2 KO mice and WT littermates (WT: 96.5±4.5 mm Hg, n=5; KO: 98.7±11.7 mm Hg, n=4, P &gt; 0.05). Taken together, NPFF and its receptor, NPFFR2, in the kidney cause salt-sensitive hypertension in mice. Uncovering the functional relevance of renal NPFF in the dynamic regulation of renal sodium transport will lead to a better understanding of blood pressure homeostasis.

Perifocal Edema in Gliomas. Pathogenesis, Clinical Picture, Treatment

Surgical treatment of malignant glial tumor is a complex task due to the lack of clear boundaries and contours, its high invasiveness in healthy brain tissues and the formation of intense edema, due to low differentiation in color and consistency between tumor and brain tissue. The main symptomatology of glial tumors is due to peritumoral edema, which can lead to severe symptoms, including neurological dysfunction, dislocation of structures and brain hernia. The main task of neurologists, neurosurgeons and resuscitators in the pre- and postoperative periods is to reduce the aggressive mass effect of the perifocal edema zone in gliomas. In recent years, steroid therapy has been the standard treatment for perifocal edema in space-occupying lesions of the brain. In recent years, the study of the role of cerebral lymphatic vessels involved in the regulation of cerebrospinal fluid and the formation of cerebral edema has changed views on the treatment of perifocal edema in gliomas. The aim of this study was to study the pathogenesis, clinical features and treatment of peritumoral edema in gliomas. The known mechanisms causing peritumoral edema in glial tumors of the brain have been studied and summarized. A comparative analysis and discussion of the results of modern methods for treating perifocal cerebral edema in glial tumors have been carried out and prospects for future methods for treating cerebral edema are presented. Further studies of perifocal edema around a glial tumor of the brain are needed to improve the prognosis of the pre- and postoperative periods and increase the effectiveness of edema treatment.

Midregional Proatrial Natriuretic Peptide (MRproANP) is associated with vertebral fractures and low bone density in patients with chronic obstructive pulmonary disease (COPD)

BackgroundPatients with COPD are often affected by loss of bone mineral density (BMD) and osteoporotic fractures. Natriuretic peptides (NP) are known as cardiac markers, but have also been linked to fragility-associated fractures in the elderly. As their functions include regulation of fluid and mineral balance, they also might affect bone metabolism, particularly in systemic disorders such as COPD.Research questionWe investigated the association between NP serum levels, vertebral fractures and BMD assessed by chest computed tomography (CT) in patients with COPD.MethodsParticipants of the COSYCONET cohort with CT scans were included. Mean vertebral bone density on CT (BMD-CT) as a risk factor for osteoporosis was assessed at the level of TH12 (AI-Rad Companion), and vertebral compression fractures were visually quantified by two readers. Their relationship with N-terminal pro-B-type natriuretic peptide (NT-proBNP), Mid-regional pro-atrial natriuretic peptide (MRproANP) and Midregional pro-adrenomedullin (MRproADM) was determined using group comparisons and multivariable analyses.ResultsAmong 418 participants (58% male, median age 64 years, FEV1 59.6% predicted), vertebral fractures in TH12 were found in 76 patients (18.1%). Compared to patients without fractures, these had elevated serum levels (p ≤ 0.005) of MRproANP and MRproADM. Using optimal cut-off values in multiple logistic regression analyses, MRproANP levels ≥ 65 nmol/l (OR 2.34; p = 0.011) and age (p = 0.009) were the only significant predictors of fractures after adjustment for sex, BMI, smoking status, FEV1% predicted, SGRQ Activity score, daily physical activity, oral corticosteroids, the diagnosis of cardiac disease, and renal impairment. Correspondingly, MRproANP (p < 0.001), age (p = 0.055), SGRQ Activity score (p = 0.061) and active smoking (p = 0.025) were associated with TH12 vertebral density.InterpretationMRproANP was a marker for osteoporotic vertebral fractures in our COPD patients from the COSYCONET cohort. Its association with reduced vertebral BMD on CT and its known modulating effects on fluid and ion balance are suggestive of direct effects on bone mineralization.Trial registrationClinicalTrials.gov NCT01245933, Date of registration: 18 November 2010.

TRPV4 Antagonist Treatment of Hydrocephalus Causes Cell and Molecular Changes in Multiple Brain Cell Types

Hydrocephalus is defined by cerebrospinal fluid (CSF) accumulation in the brain’s ventricles causing ventriculomegaly, an imbalance in CSF secretion, flow, and/or absorption. Treatments for hydrocephalus include invasive surgical procedures, which commonly fail throughout a patient’s life. Transient receptor potential vanilloid member 4 (TRPV4) is a mechanosensitive cation channel implicated in osmotic regulation. Our laboratory found that a TRPV4 antagonist, RN1734, ameliorates hydrocephalus in a rat model of congenital hydrocephalus. It was hypothesized that treatment slowed production of CSF by targeting choroid plexus (CP), a contiguous layer of tightly regulated epithelial cells, that is responsible for CSF production. However, hydrocephalus pathology can have various effects on the brain. This study focuses on changes occurring in CP epithelial cells (CPe) and glia, which have roles in brain-barrier maintenance and brain fluid/electrolyte regulation. Interestingly, CPe and glia contain many of the same channels and transporters, including TRPV4, that are important in regulating both CSF and brain interstitial fluid. These cells contain aquaporins (AQP), AQP1 in CPe, and AQP4 in glia. AQPs have been implicated in diseases associated with fluid regulation and may interact with TRPV4. We hypothesize that TRPV4 and AQPs are important in hydrocephalus pathology, and that changes may be attenuated with RN1734 treatment. A point mutation in TMEM67 results in hydrocephalus (hydro). Changes in cell morphology, gene transcription, protein expression, localization of TRPV4, AQP1, and AQP4 were observed. Postnatal day 15 (P15) untreated (unt) and RN1734-treated (RN;2mg/ml DMSO; 4mg/kg intraperitoneal injection daily P7-P14) wildtype and mutant ( Tmem67−/−) rats were utilized in this study. CPe and periventricular (PV) glia were visualized using fluorescent immunohistochemistry (IHC) of GFAP and a plasma membrane marker. Cell volume of CPe’s and process morphology of glia were altered in hydro rats. RN returned these changes to relatively normal in CPe, but not glia. Next, we used IHC to examine localization of TRPV4 and the AQPs. Increased immunoreactivity of TRPV4 and AQP1 was observed in CPe of unt and RN Tmem67−/− rats. AQP4 and TRPV4 immunoreactivity increased in the subventricular zone and PV white matter of hydro rats. TRPV4 immunoreactivity, but not AQP4, was normalized with RN. We then utilized RTqPCR to inspect transcriptional changes. The data showed increased AQP1 and decreased TRPV4 mRNA in PV cortex and CP of unt and RN Tmem67−/− rats. Previous data from our laboratory found no change in TRPV4 protein in unt Tmem67−/− CPe, but we were curious about AQP expression. The amount of AQP1 protein was increased in the CP of unt and RN Tmem67−/− rats. In PV cortex, AQP4, but not TRPV4, protein was increased in hydro rats. With RN, AQP4 protein was not normalized. In summary, TRPV4 changes in the Tmem67−/− rats returned to normal with RN, glial morphology and AQP changes did not. This may indicate residual inflammation in the Tmem67−/− rats, which we aim to address in future studies. To further elucidate TRPV4’s role in hydrocephalus pathology, future studies will explore post-translational and membrane localization changes. Overall, investigating cell and molecular changes that occur in hydrocephalus will help find better pharmacological targets for this disease. Funding: United States Department of Defense Congressionally Directed Medical Research Program Award; Hydrocephalus Association. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

RAPID ENDOGENOUS PRODUCTION OF ENDOTHELIN-1 REVEALED BY AN ENDOTHELIN NEUTRALIZING ANTIBODY IN A SERIES OF EXPERIMENTAL AND MODELING STUDIES

Objective: The endothelin pathway is implicated in driving pathophysiological changes leading to pulmonary and systemic hypertension, chronic kidney disease and heart failure. Small molecule antagonists that selectively blocked endothelin A receptors (ETA) as well as non-selective ETA and endothelin B receptor (ETB) antagonists were successfully developed for the treatment of these vascular diseases. However, the treatment-related adverse events, such as fluid retention and edema, significantly limit the utility of this class of therapeutics, especially in the heart failure patients. Design and method: A monoclonal antibody that selectively neutralizes endothelin-1 (ET-1) may offer an attractive alternative therapeutic approach that remedies ETA-mediated vasoconstriction without impacting desirable ET-3/ETB mediated fluid regulation. A selective ET-1/2 neutralizing antibody, S69glC21 was discovered and optimized through protein engineering to 80 pM and 30 pM binding affinities to ET-1 and ET-2, respectively. Results: When administered into rats exogenously infused with ET-1, S69glC21 prevented blood pressure increase. In a hypoxia-induced pulmonary hypertension rat model, S69glC21 reduced pulmonary pressure. Compared to atrasentan, a selective small molecule ETA antagonist, S69glC21 had a distinct pharmacodynamic (PD) effect characterized by initial complete inhibition followed by a delayed rise of pulmonary pressure as the hypoxia condition persisted. To further dissect these findings, S69glC21 pharmacokinetics (PK) and circulating ET-1 target engagement (TE) analysis were performed. In the S69glC21 treated rats, antibody bound ET-1 was shown to accumulate relative to baseline plasma levels at all dose levels. In the 30 mpk group, the antibody bound ET-1 accumulated nearly 40,000-fold above the baseline plasma level of 2.25 ± 0.87 pg/mL indicating a rapid production rate of ET-1. Conclusions: Thus, PK/PD modeling reveals significant druggability challenges for the development of a highly effective, commercially viable ET-1 selective neutralizing antibody for the treatment of cardiovascular, pulmonary, and/or renal diseases.

Characterisation of a Novel Osmosensitive Pathway from the Supraoptic Nucleus to the Median Preoptic Nucleus

The Supraoptic Nucleus (SON) is well regarded for the neuroendocrine release of vasopressin and oxytocin through the posterior pituitary gland. Evidence also exists for extra-pituitary efferent projections of SON neurons, mainly collaterals to the lateral hypothalamus and central amygdala. The objective of this study was to examine the existence of a central SON projection to the median preoptic nucleus (MnPO) of the hypothalamus. Microinjections of the retrograde tracer Cholera Toxin B Subunit (CTb) into the MnPO of male Wistar rats (n = 3) retrogradely labelled SON neurons. Fluorescence immunohistochemistry revealed equal involvement of vasopressin (AVP) and oxytocin (OXT) — producing SON neurons (n = 107 AVP+/CTb+, n = 110 OXT+/ CTb+, n = 417 total CTb+ neurons). This major collateral projection was also examined in an animal model of Polycystic Kidney Disease, the Lewis Polycystic Kidney (LPK) rat (n = 3 animals; n = 104 AVP+/CTb+, n = 41 OXT+/CTb+, n = 372 total CTb+ neurons) and its healthy Lewis control (n = 3 animals; n = 115 AVP+/CTb+, n = 100 OXT+/CTb+, n = 430 total CTb+ neurons). Although the function of this projection is currently unclear, preliminary data in a subset of LPKs shows these SON neurons with MnPO collateral projections are activated by osmotic stressors (e.g., hypertonic saline). In summary, we report a major collateral projection from the SON to MnPO that is activated by osmotic stress. Given the well-known role of the MnPO in drinking behaviour, we suggest this SON-MnPO circuit may be involved in the coordination of fluid regulation and drinking behaviour. This project was funded by Macquarie University. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Development of Fluorescent Sensors for Biorelevant Anions in Aqueous Media Using Positively Charged Quantum Dots.

Quantum dots (QDs) have captured the attention of the scientific community due to their unique optical and electronic properties, leading to extensive research for different applications. They have also been employed as sensors for ionic species owing to their sensing properties. Detecting anionic species in an aqueous medium is a challenge because the polar nature of water weakens the interactions between sensors and ions. The anions bicarbonate (HCO3-), carbonate (CO32-), sulfate (SO42-), and bisulfate (HSO4-) play a crucial role in various physiological, environmental, and industrial processes, influencing the regulation of biological fluids, ocean acidification, and corrosion processes. Therefore, it is necessary to develop approaches capable of detecting these anions with high sensitivity. This study utilized CdTe QDs stabilized with cysteamine (CdTe-CYA) as a fluorescent sensor for these anions. The QDs exhibited favorable optical properties and high photostability. The results revealed a gradual increase in the QDs' emission intensity with successive anion additions, indicating the sensitivity of CdTe-CYA to the anions. The sensor also exhibited selectivity toward the target ions, with good limits of detection (LODs) and quantification (LOQs). Thus, CdTe-CYA QDs show potential as fluorescent sensors for monitoring the target anions in water sources.

Oxytocin-receptor-expressing neurons in the lateral parabrachial nucleus activate widespread brain regions predominantly involved in fluid satiation

Fluid satiation is an important signal and aspect of body fluid homeostasis. Oxytocin-receptor-expressing neurons (OxtrPBN) in the dorsolateral subdivision of the lateral parabrachial nucleus (dl LPBN) are key neurons which regulate fluid satiation. In the present study, we investigated brain regions activated by stimulation of OxtrPBN neurons in order to better characterise the fluid satiation neurocircuitry in mice. Chemogenetic activation of OxtrPBN neurons increased Fos expression (a proxy marker for neuronal activation) in known fluid-regulating brain nuclei, as well as other regions that have unclear links to fluid regulation and which are likely involved in regulating other functions such as arousal and stress relief. In addition, we analysed and compared Fos expression patterns between chemogenetically-activated fluid satiation and physiological-induced fluid satiation. Both models of fluid satiation activated similar brain regions, suggesting that the chemogenetic model of stimulating OxtrPBN neurons is a relevant model of physiological fluid satiation. A deeper understanding of this neural circuit may lead to novel molecular targets and creation of therapeutic agents to treat fluid-related disorders.

Metabolic Water As a Route for Water Acquisition in Vertebrates Inhabiting Dehydrating Environments.

Vertebrates have expanded their habitats during evolution, which accompanies diversified routes for water acquisition. Water is acquired by oral intake and subsequent absorption by the intestine in terrestrial and marine animals which are subjected to constant dehydration, whereas most water is gained osmotically across body surfaces in freshwater animals. In addition, a significant amount of water, called metabolic water, is produced within the body by the oxidation of hydrogen in organic substrates. The importance of metabolic water production as a strategy for water acquisition has been well documented in desert animals, but its role has attracted little attention in marine animals which also live in a dehydrating environment. In this article, the author has attempted to reevaluate the role of metabolic water production in body fluid regulation in animals inhabiting desiccating environments. Because of the exceptional ability of their kidney, marine mammals are thought to typically gain water by drinking environmental seawater and excreting excess NaCl in the urine. On the other hand, it is established that marine teleosts drink seawater to enable intestinal water and ion absorption, and the excess NaCl is excreted by branchial ionocytes. In addition to the oral route, we suggest through experiments using eels that water production by lipid metabolism is an additional route for water acquisition when they encounter seawater. It seems that metabolic water production contributes to counteract dehydration before mechanisms for water regulation are reversed from excretion in freshwater to acquisition in seawater.

Analysis of Sodium Levels in Different Brands of Edible Salts by Flame Photometer

Sodium is a key element for all living things, mainly animals, some plant species, and humans. In animals, sodium ions are necessary for the regulation of blood and body fluids, the transmission of nerve impulses, heart activity, and certain metabolic functions. Sodium is the chief cation in the extracellular compartment of an animal body. Sodium plays a vital role not only in the human body but also in various food types. Salt, also known as sodium chloride, is about 40% sodium and 60% chloride. It flavors food and is used as a binder and stabilizer. The sodium content in different brands of edible salts can be analyzed using flame photometry. Flame photometry, also called flame atomic emission spectrometry, is a branch of atomic spectroscopy in which the species examined in the spectrometer are in the form of atoms. The samples used for analysis are junk foods, which have become a common trend among all generations. A total of 13 brands were analyzed for iodine content. From that, two commonly used brands were selected and analyzed for estimating the sodium and potassium contents in them by flame photometry. The analysis helps in creating awareness among all generations to reduce the sodium intake in order to prevent problems like hypertension, hyponatremia, hypernatremia, and associated medical complications in the future.

Research on hydrodynamic characteristics and performance improvement of ball valve integrating fluid regulation and energy harvesting

Research on hydrodynamic characteristics and performance improvement of ball valve integrating fluid regulation and energy harvesting

Potential Role of the Skin in Hypertension Risk Through Water Conservation.

Previous basic and clinical investigations have identified various pathogenic factors and determinants of risk that contribute to hypertension. Nevertheless, the pathogenesis of hypertension has not been fully elucidated. Moreover, despite the availability of antihypertensive medications for the management of blood pressure, treatments that address the full spectrum of the pathophysiological defects underpinning hypertension remain to be identified. To further investigate the mechanisms of primary hypertension, it is imperative to consider novel potential aspects, such as fluid management by the skin, in addition to the conventional risk factors. There is a close association between body fluid regulation and blood pressure, and the kidney, which, as the principal organ responsible for body fluid homeostasis, is the primary target for research in the field of hypertension. In addition, the skin functions as a biological barrier, potentially contributing to body fluid regulation. In this review, we propose the hypothesis that changes in skin water conservation are associated with hypertension risk based on recent findings. Further studies are required to clarify whether this novel hypothesis is limited to specific hypertension or applies to physiological blood pressure regulation.

Authentication of a lophotrochozoan adipokinetic hormone receptor in a Gastropod, Aplysia californica

Gonadotropin-releasing hormone (GnRH) superfamily comprises multiple families of signaling peptides in both protostomes and deuterostomes. Among this superfamily, vertebrate GnRH stimulates reproduction, but other GnRH superfamily members elicit diverse pleiotropic effects. Within the GnRH superfamily members, adipokinetic hormone (AKH) and its receptor are well described in ecdysozoans but understudied in other lineages. To fill this knowledge gap, we deorphanized a putative receptor for a lophotrochozoan AKH in a gastropod mollusk, Aplysia californica, and named it Aplca-AKHR. Phylogenetic analysis revealed an orthologous relationship of Aplca-AKHR with ecdysozoan AKHRs and other putative lophotrochozoan AKHRs. Aplca-AKHR bound specifically to the previously identified Aplca-AKH with high affinity and activated the inositol phosphate pathway. Aplca-AKHR was expressed widely among central and peripheral tissues, but most prominently in several central ganglia and the heart. The expression of Aplca-AKHR was downregulated by a hyposaline challenge, consistent with a role in volume and fluid regulation previously described for its ligand, Aplca-AKH. In summary, this is the first pairing of a lophotrochozoan AKH with its cognate receptor. Expression data further support diverse central and peripheral roles, including volume and fluid control, of this ligand/receptor pair.

Peritumoral Edema in Gliomas: A Review of Mechanisms and Management.

Treating malignant glioma is challenging owing to its highly invasive potential in healthy brain tissue and the formation of intense surrounding edema. Peritumoral edema in gliomas can lead to severe symptoms including neurological dysfunction and brain herniation. For the past 50 years, the standard treatment for peritumoral edema has been steroid therapy. However, the discovery of cerebral lymphatic vessels a decade ago prompted a re-evaluation of the mechanisms involved in brain fluid regulation and the formation of cerebral edema. This review aimed to describe the clinical features of peritumoral edema in gliomas. The mechanisms currently known to cause glioma-related edema are summarized, the limitations in current cerebral edema therapies are discussed, and the prospects for future cerebral edema therapies are presented. Further research concerning edema surrounding gliomas is needed to enhance patient prognosis and improve treatment efficacy.

Hydrate-based composition separation of R32/R1234yf mixed working fluids applied in composition-adjustable organic Rankine cycle

Precise composition regulation of mixed working fluids is core to high performance composition-adjustable organic Rankine cycle (CA-ORC). However, most composition separation methods couldn't achieve precise regulation, limiting the application of CA-ORC. The hydrate-based composition separation proposed a promising avenue for precise regulation. In order to better apply to the CA-ORC, the separation characteristics of mixed working fluid hydrates should be clearly clarified, which remains to be a challenge. Facing the challenge, this study experimentally investigated hydrate-based composition regulation of R32/R1234yf mixed working fluid that possess both environmental and excellent thermodynamic properties. The separation characteristics of mixed working fluids were clarified, and the optimal separation operating conditions were analyzed covering a broad range of temperature (275.00 K–282.00 K) and pressure (0.30 MPa–0.54 MPa). The results show that hydrate-based composition regulation of R32/R1234yf can achieve excellent regulation performance, with composition change of R32 of 11.14–18.21 mol% in 90 min. Lower temperatures and higher pressures can lead to a better separation performance. Separation factor of R32 reach the maximum of 29.702, which is 4.12 times higher than the minimum. This study may provide a guidance to search energy-saving operating conditions for hydrate-based composition regulation and support its application in CA-ORC.