Disorders of Acid-Base Balance: New Perspectives

Constructing a prediction model for acute pancreatitis severity based on liquid neural network

Acute pancreatitis (AP) is a common disease, and severe acute pancreatitis (SAP) has a high morbidity and mortality rate. Early recognition of SAP is crucial for prognosis. This study aimed to develop a novel liquid neural network (LNN) model for predicting SAP. This study retrospectively analyzed the data of AP patients admitted to the Second Affiliated Hospital of Guilin Medical University between January 2020 and June 2024. Data imbalance was dealt with by data preprocessing and using the synthetic minority oversampling technique (SMOTE). A new feature selection method was designed to optimize model performance. Logistic regression (LR), decision tree (DCT), random forest (RF), Extreme Gradient Boosting (XGBoost), and LNN models were built. The model's performance was evaluated by calculating the area under the receiver operating characteristic (ROC) curve (AUC) and other statistical metrics. In addition, SHapley Additive exPlanations (SHAP) analysis was used to interpret the prediction results of the LNN model. The LNN model performed best in predicting AP severity, with an AUC value of 0.9659 and accuracy, precision, recall, F1 score, and specificity higher than 0.90. SHAP analysis revealed key predictors, such as calcium level, amylase activity, and percentage of basophils, which were strongly associated with AP severity. As an emerging machine learning tool, the LNN model has demonstrated excellent performance and potential in AP severity prediction. The results of this study support the idea that LNN models can be applied to early severity assessment of AP patients in a clinical setting, which can help optimize treatment plans and improve patient prognosis.

A second act for spironolactone: cognitive benefits in renal dysfunction - a critical review

Renal dysfunction or Chronic kidney disease (CKD) are increasingly associated with cognitive deficit and memory impairment, suggesting a crucial kidney-brain axis. This review examines spironolactone's emerging role as a neuroprotective agent in the context of renal dysfunction-induced cognitive impairment. As a selective mineralocorticoid receptor (MR) antagonist, spironolactone demonstrates multifaceted protective mechanisms beyond its well established renoprotective effects. Evidences also suggests that spironolactone attenuates neuroinflammation, mitigates oxidative stress in brain, preserve blood-brain barrier (BBB) integrity and regulates hormonal imbalances associated with renal dysfunction. This review focuses on the reported beneficial effects of spironolactone in various neurodegenerative diseases (NDDs). These mechanisms collectively protect against the neurodegeneration in memory impairment induced by renal dysfunction. The dual action of spironolactone on both renal and cerebral tissues presents a novel therapeutic advantage in addressing this complex pathophysiology. This study elucidates multiple beneficial mechanisms by which spironolactone addresses cognitive impairment associated with renal dysfunction. Spironolactone enhances BBB protection and restores BBB integrity which is often compromised with renal dysfunction. It promotes neuroplasticity (allowing for improved neural adaptation and cognitive function), additionally mediates cerebral blood flow (CBF) ensuring adequate oxygen and nutrient delivery to brain. Spironolactone's anti-inflammatory effects by inhibiting the nuclear factor-kappa B (NF-κB) pathway and modulation of neuregulin1 (NRG1)/v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ERBB4) signaling effectively reduce neuroinflammation that contributes to memory impairment. It also mitigates oxidative stress by targeting NADPH-oxidase (NOX), a major source of reactive oxygen species (ROS) in the central nervous system (CNS). Spironolactone also maintains hormonal balance, particularly regarding aldosterone levels, which become dysregulated in renal dysfunction and negatively impact brain function. These insights provide new possibilities for developing targeted therapies against renal dysfunction-induced memory impairment.

Multisystem impact of altering acid load of ingested exogenous ketone supplements at rest in young healthy adults

Disruptions to acid-base are observed in extreme environments as well as respiratory and metabolic diseases. Exogenous ketone supplements (EKSs) have been proposed to mitigate these processes and provide therapeutic benefits by altering acid-base balance and metabolism, but direct comparison of various forms of EKS is lacking. Twenty healthy participants (M/F: 10/10; age: 20.6 ± 2.0 yr, height: 1.72 ± 0.08 m, body mass: 67.9 ± 10.2 kg) participated in a single-blind, randomized crossover design comparing ingestion of the (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (R-BD R-βHB) ketone monoester (KME), KME + sodium bicarbonate (KME + BIC), an R-βHB ketone salt (KS), and a flavor-matched placebo. Acid-base balance, blood R-βHB, glucose and lactate concentrations, blood gases, respiratory gas exchange, autonomic function, and cognitive performance were assessed at baseline and various timepoints for up to 120 min after ingestion. Compared with placebo (PLA), blood R-βHB concentrations were elevated in each EKS condition (∼2-4 mM; P < 0.01), and blood glucose concentrations were lower. Blood pH was lower in KME (-0.07 units), and higher in KS and KME + BIC (+0.05 units), compared with PLA (all P < 0.05). Heart rate was elevated, and autonomic function was altered in KME + BIC. There were no differences between conditions for blood gases, respiratory gas exchange, blood pressure, or cognitive performance. Exploratory analyses of between-sex differences demonstrated males and females responded similarly across all outcome measures. Altering the acid load of EKS modulated the response of blood R-βHB and glucose concentrations but had only modest effects on other outcome measures at rest in young healthy adults, with no differences observed between sexes.NEW & NOTEWORTHY Altering the acid load of ingested exogenous ketone supplements altered post-ingestion responses of circulating glucose and R-βHB concentrations, heart rate, and autonomic function, but did not alter blood gases, respiratory gas exchange, blood pressure, or cognitive performance at rest in young healthy adults.

Unveiling the substantial role of rutin in the management of drug-induced nephropathy using network pharmacology and molecular docking

INTRODUCTION

Flavonoids including quercetin, kaempferol, myricetin, rutin etc. have always been a part of traditional Chinese medicine for the treatment of several ailments. Rutin (RT), also known as rutoside, sophorin is one of the flavanol glycoside having structure resemblance with quercetin. It is found to exhibit several biological activities viz. anti-inflammatory, anticancer, antioxidant, cardioprotective, antidepressant, neuroprotective etc. but the mechanisms by which it exhibits these effects is still under research.

AIM

The protective effects of rutin against drug induced nephropathy have already been discovered. Therefore, in this study, the main focus is to explore the mechanism by which rutin provides protection against drug-induced nephropathy using modern method like network pharmacology and molecular docking.

MATERIALS AND METHODS

Genes linked to drug-induced nephropathy and targets connected with rutin were obtained by searching through a number of extensive databases, including David software, Venn plot database, Swiss target prediction database, String database, Gene card & OMIM database, and Pubchem. In order to locate mapping targets, the acquired targets were examined and intersected. A protein-protein interaction (PPI) network was then built to find potential targets.

RESULTS

From the KEGG pathway, the target pathway responsible for drug-induced nephropathy were found to be XDH, HSD17B2, MET, PRKCB, CD38, ALDH2, CDK1, PTK2, CYP19A1, TNF, F2, PTGS2, ESR1, GSK3B, GLO1, ALOX12, MMP3, PRKCZ, CXCR1, CA4, EGFR, PDE5A, F10, AKR1B1, DRD4, TERT, CA3, PLG, TP53, PRKCH, PIK3R1, PRKACA, CYP1B1, ALOX5, PLK1, CHEK1, KCNH2, PRKCD, MAPT, MPO, NOX4, AVPR2, ACHE, MCL1, KDR, ABCG2, CCR1, PIK3CG, FLT3, ADORA1, IL2, SYK, IGF1R, CA2, SERPINE1, INSR, PRKCA, APP, MMP9. From these identified targets, the 14 selected pathways which have major role in providing protection in drug-induced nephropathy have been discussed.

CONCLUSION

As RT can inhibit various metabolic and proinflammatory pathways involved, it can help in prevention and treatment of drug-induced nephropathy.

FUTURE ASPECTS

The revelation of mode of action of bioactive constituent rutin against drug-induced nephropathy provides a theoretical basis for designing more promising compounds in future for treatment of nephropathy.

Selective Detection of Divalent Cations (Cu2+, Zn2+, Pb2+) and Anions (SO42-, S2-, CO32-) Using a pH-Sensitive Multi-functional Schiff Base in Neutral Medium

A new Schiff base-based multi-cation/anion probe (L) has been synthesized and characterized using HR-MS, FT-IR, 1H, and 13C NMR techniques. The Schiff base motif provides specific binding sites that detect cations and anions by generating distinct optical output signals upon interaction. A noticeable color change of the probe solution was observed from pale yellow to various shades of yellow upon adding cations such as Cu2+, Zn2+, and Pb2+ and anions such as CO32⁻, S2⁻, and SO42⁻. This color change results from forming complexes like M3L2 with metal ions. Whereas origin of color in presence of anion were attributed due to the deprotonation of acidic proton in the ligand. Moreover, the complexes formed by Zn2+, S2/CO32⁻ ion with L are fluorescent, enabling the detection of Cu2+ and SO42⁻ using the Stern-Volmer plot, with a limit of detection (LODs) of 8.48 µM and 10.47 µM, respectively. Additionally, increasing the pH of the probe solution above 8 reveals a significant enhancement of fluorescence intensity due to the deprotonation of phenolic -OH and amide -NH in the presence of hydroxide ions. This emission in the basic medium is quenched by Cu2+ ions and restored when Cu2+ is complexed with EDTA. A logic gate has also been constructed for understanding the TURN-OFF-TURN-ON mechanism involving Cu2+ ions and EDTA. Overall, the versatile performance of a single probe L opens up new possibilities as a multifunctional sensor, making it highly suitable for practical applications.

Independent variables of pH: Ten Knights of the Hydrogen Ion Kingdom-Part I. A prospective observational study

CO2, HCO3, SID, and total weak acids have been defined as pH's independent variables. However, according to Gamble, HCO3 should be equal to the difference between the sum of cations and the sum of anions besides HCO3. Therefore, if this mathematical expression is substituted for HCO3 in the Henderson-Hasselbalch equation, all independent variables of pH can be demonstrated. Our aim is to test this theory in this study. This prospective observational study was conducted between 2019 and 2020. All admitted patients to the intensive care unit who were >18 years old were included. Demographic data, blood gas parameters, albumin, magnesium, and inorganic phosphorus levels, and outcomes were recorded twice (at admission and at the 24th hour). The multivariate linear regression model was used to determine pH's independent variables. In the multivariate linear regression model, pH was significantly increased by each unit increase in Na, K, Ca, and Mg (mmol L-1). In contrast, pH was significantly decreased by each unit increase in CO2, Cl, lactate, albumin (g dL-1), inorganic phosphorus (mg dL-1), and the strong ion gap. Ten independent variables can accurately predict the changes in pH. For this reason, all ten independent variables should be separately evaluated when interpreting the acid-base status. With this understanding, all algorithms regarding acid-base evaluation may become unnecessary.

The study of intercalated cells using ex vivo techniques: primary cell culture, cell lines, kidney slices, and organoids

This review summarizes methods to study kidney intercalated cell (IC) function ex vivo. While important for acid-base homeostasis, IC dysfunction is often not recognized clinically until it becomes severe. The advantage of using ex vivo techniques is that they allow for the differential evaluation of IC function in controlled environments. Although in vitro kidney tubular perfusion is a classical ex vivo technique to study IC, here we concentrate on primary cell cultures, immortalized cell lines, and ex vivo kidney slices. Ex vivo techniques are useful in evaluating IC signaling pathways that allow rapid responses to extracellular changes in pH, CO2, and bicarbonate (HCO3-). However, these methods for IC work can also be challenging, as cell lines that recapitulate IC do not proliferate easily in culture. Moreover, a "pure" IC population in culture does not necessarily replicate its collecting duct (CD) environment, where ICs are surrounded by the more abundant principal cells (PCs). It is reassuring that many findings obtained in ex vivo IC systems signaling have been largely confirmed in vivo. Some of these newly identified signaling pathways reveal that ICs are important for regulating NaCl reabsorption, thus suggesting new frontiers to target antihypertensive treatments. Moreover, recent single-cell characterization studies of kidney epithelial cells revealed a dual developmental origin of IC, as well as the presence of novel CD cell types with certain IC characteristics. These exciting findings present new opportunities for the study of IC ex vivo and will likely rediscover the importance of available tools in this field.NEW & NOTEWORTHY The study of kidney intercalated cells has been limited by current cell culture and kidney tissue isolation techniques. This review is to be used as a reference to select ex vivo techniques to study intercalated cells. We focused on the use of cell lines and kidney slices as potential useful models to study membrane transport proteins. We also review how novel collecting duct organoids may help better elucidate the role of these intriguing cells.

Correlation of serum biochemical parameters and saliva pH in healthy individuals

Saliva has the potential to work alongside needles in standard medical diagnosis. Yet the number of studies aimed at deciphering the biochemical communication between saliva and the rest of the body's systems is still very limited. The aim of this study is to investigate the interfluid interaction between saliva and serum by determining the correlation between saliva pH and serum biochemical parameters under mild conditions. Ultimately, using saliva may provide a stress-free diagnostic tool, but more ambitiously, the pH of saliva could present a genuine cost-effective screening tool that may immensely benefit areas with limited access to health care and diagnostic labs. Saliva and blood samples were collected from 43 randomly selected children (7-12 years), living in Jeddah, free from obesity and chronic or systemic body and mouth diseases. A complete serum biochemical analysis was performed, and the salivary pH of all samples was measured immediately at the time of collection. The correlations between saliva pH and serum biochemical parameters were investigated using Univariate and multiple linear regression models. Our results showed that pH has a weak significant positive correlation with total protein and a negative weak significant correlation with urea. Weak correlations suggest the existence of more serum factors to be investigated for their effect on the pH using a stepwise multiple linear regression. The multiple linear models' calculated saliva pH values were close to the measured values, demonstrating its possible capacity to predict saliva pH using serum parameters. The regression model's successful prediction of saliva pH using serum biochemicals reflects the significant correlations between the body fluids' parameters and invites more research to elucidate these relationships.

Serum Phosphorus, Serum Bicarbonate, and Renal Function in Relation to Liver CYP1A2 Activity

The liver plays an important role in normal metabolism and physiological functions such as acid-base balance; however, limited epidemiologic studies have investigated how the liver contributes toward acid-base balance using non-invasive biomarkers. We determined associations between serum biomarkers related to acid-base balance and renal function with liver CYP1A2 activity. We used data from 1381 participants of the 2009-2010 National Health and Nutrition Examination Survey (NHANES) with measurements of serum phosphorus, serum bicarbonate, caffeine intake, caffeine metabolites, and estimated glomerular filtration rate (eGFR). Liver CYP1A2 activity was estimated using urine caffeine metabolite indices, which were calculated as the ratio of one of the urine caffeine metabolites (i.e., paraxanthine and 1-methyluric acid) to caffeine intake. We analyzed associations in the whole data set and in different strata of hepatic steatosis index (HSI) based on different cut-points. We found that serum bicarbonate was positively associated with CYP1A2 activity in the whole data set when comparing persons with bicarbonate at Q4 to Q1 (β = 0.18, p = 0.10 for paraxanthine; β = 0.20, p = 0.02 for 1-methyluric acid). Furthermore, serum phosphorus was positively associated with CYP1A2 activity only in the stratum of 30 ≤ HSI < 36. Lastly, low eGFR was significantly associated with lower CYP1A2 activity measured with paraxanthine in the whole dataset and in all the strata with HSI < 42; when comparing eGFR < 60 to eGFR > 90, β estimates ranged from -0.41 to -1.38, p-values ranged from 0.0018 to 0.004. We observed an opposite trend in the highest stratum (HSI ≥ 42). Non-invasive measurements of serum bicarbonate, serum phosphorus, and eGFR have dynamic associations with CYP1A2 activity. These associations depend on the extent of liver damage and the caffeine metabolite used to assess CYP1A2 activity.

Dynamic Modeling of Carbon Dioxide Transport through the Skin Using a Capnometry Wristband

The development of a capnometry wristband is of great interest for monitoring patients at home. We consider a new architecture in which a non-dispersive infrared (NDIR) optical measurement is located close to the skin surface and is combined with an open chamber principle with a continuous circulation of air flow in the collection cell. We propose a model for the temporal dynamics of the carbon dioxide exchange between the blood and the gas channel inside the device. The transport of carbon dioxide is modeled by convection-diffusion equations. We consider four compartments: blood, skin, the measurement cell and the collection cell. We introduce the state-space equations and the associated transition matrix associated with a Markovian model. We define an augmented system by combining a first-order autoregressive model describing the supply of carbon dioxide concentration in the blood compartment and its inertial resistance to change. We propose to use a Kalman filter to estimate the carbon dioxide concentration in the blood vessels recursively over time and thus monitor arterial carbon dioxide blood pressure in real time. Four performance factors with respect to the dynamic quantification of the CO₂ blood concentration are considered, and a simulation is carried out based on data from a previous clinical study. These demonstrate the feasibility of such a technological concept.

The association between albumin corrected anion gap and ICU mortality in acute kidney injury patients requiring continuous renal replacement therapy

The relationship between albumin corrected anion gap (ACAG) and mortality in acute kidney injury (AKI) patients who received continuous renal replacement therapy (CRRT) has not been investigated in any previous studies. This study aimed to investigate the relationship between ACAG at CRRT initiation and all-cause mortality among these patients in the intensive care unit (ICU). Patients diagnosed with AKI and treated with CRRT in the ICU from the Medical Information Mart for Intensive Care-IV version 1.0 (MIMIC IV) database and Huzhou Central Hospital were retrospectively enrolled. Participants were divided into two groups: the normal ACAG group (12-20 mmol/L) and high ACAG group (> 20 mmol/L). The Kaplan-Meier method and log-rank test were used to compare the survival rate between the two groups. Restricted cubic spine (RCS) and Cox proportional-hazards models were utilized to analyze the relationship between ACAG at CRRT initiation and ICU all-cause mortality of these patients. A total of 708 patients met the inclusion criteria in the study. The all-cause mortality of these patients during ICU hospitalization was 41.95%. Patients in the high ACAG group exhibited significantly higher ICU all-cause mortality rate than patients in the normal ACAG group (all P < 0.001). The Kaplan-Meier survival curves showed that the normal ACAG group had a higher ICU cumulative survival rate than the high ACAG group (log-rank test, χ₁²= 13.620, χ₂² = 12.460, both P < 0.001). In the multivariate COX regression analyses, patients with higher ACAG (> 20 mmol/L) levels at the time of CRRT initiation in the MIMIC IV database and Huzhou Central Hospital were significantly correlated with ICU all-cause mortality after adjusting multiple potential confounding factors with hazard ratios of 2.852 (95% CI 1.718-4.734) and 2.637(95% CI 1.584-4.389), respectively. In critically AKI patients who undergo CRRT, higher ACAG (> 20 mmol/L) level at the initiation of CRRT was significantly correlated with ICU all-cause mortality. Therefore, clinicians should pay more attention to those patients with a higher ACAG value.

Early Blood Analysis and Gas Exchange Monitoring in the Canine Neonate: Effect of Dam’s Size and Birth Order

Simple Summary

The complications that are observed during parturition are events that affect the vitality of the newborn and can also compromise their health by predisposing them to fetal hypoxia, increasing newborn mortality. Blood gas analysis to measure the main biomarkers associated with hypoxia evaluates the physiological and metabolic alterations derived from this state, and these could help identify if said markers respond to maternal or neonatal causes. This study aimed to assess the effect of the dam’s size, the birth order, and the presentation of blood gas alterations. Recognizing if these elements are intertwined may enhance newborns’ life expectancy by enabling the planning of a perinatal protocol to avoid serious metabolic consequences that are derived from prolonged hypoxia.

Abstract

In canines, size at birth is determined by the dam’s weight, which would probably affect the newborn’s viability due to litter size and birth order. Fetal hypoxia causes distress and acidemia. Identifying physiological blood alterations in the puppy during the first minute of life through the blood gas exchange of the umbilical cord could determine the puppy’s risk of suffering asphyxiation during labor. This study aimed to evaluate the effect of the birth order and dam’s size during spontaneous labor and the alterations during the first minute of life. The results indicate that the dam’s size and the birth order have considerable physiological and metabolic effects in the puppies, mainly in birth order 1 (BO1) in small-size dogs, while in the medium size, the last puppy presented more alterations, probably because of a prolonged whelping which could have fostered hypoxic processes and death. Likewise, with large-size dogs, intrapartum asphyxiation processes were registered during the first minute of life in any birth order.

Study of Utility of Basic Arterial Blood Gas Parameters and Lactate as Prognostic Markers in Patients With Severe Dengue

Background

The importance of prognostication in critical care cannot be over-emphasized, especially in the context of diseases like dengue, as their presentation may vary from mild fever to critical life-threatening illness. With the help of prognostic markers, it is possible to identify patients at higher risk and thus improve their outcome with timely intervention. Basic arterial blood gas (ABG) parameters, i.e., potential of hydrogen (pH), partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2) and bicarbonate are useful parameters, especially in critical care medicine as they are known to vary with the severity of illness. Hyperlactatemia is often referred to as a “powerful predictor of mortality”. Basic ABG parameters and lactate have been used as an essential prognostic modality in critically ill patients for decades; however, the evidence remains limited for their role as prognostic markers in patients with severe dengue.

Method

We carried out an observational retrospective cohort study comprising 163 patients with severe dengue, admitted between July 2021 and November 2021 at Medical Intensive Care Unit (MICU) of Shri Ram Murti Smarak Institute of Medical Sciences (SRMS IMS), Bareilly, Uttar Pradesh, India. Basic ABG parameters and lactate levels at the time of admission to MICU were compared between survivor and non-survivor groups of patients with severe dengue in order to evaluate their prognostic utility as predictors of mortality.

Results

pH (p<0.0001), PO2 (p=0.01) and bicarbonate (<0.0001) levels were significantly lower, while PCO2 (p=0.002) and lactate (p<0.0001) levels were significantly higher in non-survivor group as compared to survivor group. Lactate was found to be the best prognostic marker with Area Under the Curve (AUC) of 88.7% on Receiver Operating Characteristics (ROC) analysis.

Conclusion

Basic arterial blood gas parameters and lactate can be used as feasible prognostic markers in patients with severe dengue.

Alkalosis-induced hypoventilation in cystic fibrosis: The importance of efficient renal adaptation

The lungs and kidneys are pivotal organs in the regulation of body acid-base homeostasis. In cystic fibrosis (CF), the impaired renal ability to excrete an excess amount of HCO₃ ^- into the urine leads to metabolic alkalosis [P. Berg et al., J. Am. Soc. Nephrol. 31, 1711-1727 (2020); F. Al-Ghimlas, M. E. Faughnan, E. Tullis, Open Respir. Med. J. 6, 59-62 (2012)]. This is caused by defective HCO₃ ^- secretion in the β-intercalated cells of the collecting duct that requires both the cystic fibrosis transmembrane conductance regulator (CFTR) and pendrin for normal function [P. Berg et al., J. Am. Soc. Nephrol. 31, 1711-1727 (2020)]. We studied the ventilatory consequences of acute oral base loading in normal, pendrin knockout (KO), and CFTR KO mice. In wild-type mice, oral base loading induced a dose-dependent metabolic alkalosis, fast urinary removal of base, and a moderate base load did not perturb ventilation. In contrast, CFTR and pendrin KO mice, which are unable to rapidly excrete excess base into the urine, developed a marked and transient depression of ventilation when subjected to the same base load. Therefore, swift renal base elimination in response to an acute oral base load is a necessary physiological function to avoid ventilatory depression. The transient urinary alkalization in the postprandial state is suggested to have evolved for proactive avoidance of hypoventilation. In CF, metabolic alkalosis may contribute to the commonly reduced lung function via a suppression of ventilatory drive.

Acid-Base Balance, Blood Gases Saturation, and Technical Tactical Skills in Kickboxing Bouts According to K1 Rules

Simple Summary

The aim of our study was to analyze the changes in ABB after a three-round kickboxing fight and the level of technical and tactical skills presented during the fight. Fighting in kickboxing under K1 rules takes place with a high presence of anaerobic metabolism. Kickboxing athletes must have a good tolerance for metabolic acidosis and the ability to conduct an effective duel despite ABB disorders. Properly developed post-workout regeneration also plays an extremely important role.

Abstract

Background: Acid–base balance (ABB) is a major component of homeostasis, which is determined by the efficient functioning of many organs, including the lungs, kidneys, and liver, and the proper water and electrolyte exchange between these components. The efforts made during competitions by combat sports athletes such as kickboxers require a very good anaerobic capacity, which, as research has shown, can be improved by administering sodium bicarbonate. Combat sports are also characterized by an open task structure, which means that cognitive and executive functions must be maintained at an appropriate level during a fight. The aim of our study was to analyze the changes in ABB in capillary blood, measuring levels of H⁺, pCO₂, pO₂, HCO₃⁻, BE and total molar CO₂ concentration (TCO₂), which were recorded 3 and 20 min after a three-round kickboxing bout, and the level of technical and tactical skills presented during the fight. Methods: The study involved 14 kickboxers with the highest skill level (champion level). Statistical comparison of mentioned variables recorded prior to and after a bout was done with the use of Friedman’s ANOVA. Results: 3 min after a bout, H⁺ and pO₂ were higher by 41% and 11.9%, respectively, while pCO₂, HCO₃⁻, BE and TO₂ were lower by 14.5%, 39.4%, 45.4% and 34.4%, respectively. Furthermore, 20 min after the bout all variables tended to normalization and they did not differ significantly compared to the baseline values. Scores in activeness of the attack significantly correlated (r = 0.64) with pre–post changes in TCO₂. Conclusions: The disturbances in ABB and changes in blood oxygen and carbon dioxide saturation observed immediately after a bout indicate that anaerobic metabolism plays a large part in kickboxing fights. Anaerobic training should be included in strength and conditioning programs for kickboxers to prepare the athletes for the physiological requirements of sports combat.

The Alteration of Chloride Homeostasis/GABAergic Signaling in Brain Disorders: Could Oxidative Stress Play a Role?

In neuronal precursors and immature neurons, the depolarizing (excitatory) effect of γ-Aminobutyric acid (GABA) signaling is associated with elevated [Cl⁻]_i; as brain cells mature, a developmental switch occurs, leading to the decrease of [Cl⁻]_i and to the hyperpolarizing (inhibitory) effect of GABAergic signaling. [Cl⁻]_i is controlled by two chloride co-transporters: NKCC1, which causes Cl⁻ to accumulate into the cells, and KCC2, which extrudes it. The ontogenetic upregulation of the latter determines the above-outlined switch; however, many other factors contribute to the correct [Cl⁻]_i in mature neurons. The dysregulation of chloride homeostasis is involved in seizure generation and has been associated with schizophrenia, Down’s Syndrome, Autism Spectrum Disorder, and other neurodevelopmental disorders. Recently, much effort has been put into developing new drugs intended to inhibit NKCC1 activity, while no attention has been paid to the origin of [Cl⁻]_i dysregulation. Our study examines the pathophysiology of Cl⁻ homeostasis and focuses on the impact of oxidative stress (OS) and inflammation on the activity of Cl⁻ co-transporters, highlighting the relevance of OS in numerous brain abnormalities and diseases. This hypothesis supports the importance of primary prevention during pregnancy. It also integrates the therapeutic framework addressed to restore normal GABAergic signaling by counteracting the alteration in chloride homeostasis in central nervous system (CNS) cells, aiming at limiting the use of drugs that potentially pose a health risk.

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

Here the hypothesis that linearized esculentin 2EM (E2EM-lin) from Glandirana emeljanovi possesses pH dependent activity is investigated. The peptide showed weak activity against Gram-negative bacteria (MLCs ≥ 75.0 μM) but potent efficacy towards Gram-positive bacteria (MLCs ≤ 6.25 μM). E2EM-lin adopted an α-helical structure in the presence of bacterial membranes that increased as pH was increased from 6 to 8 (↑ 15.5-26.9%), whilst similar increases in pH enhanced the ability of the peptide to penetrate (↑ 2.3-5.1 mN m^-1) and lyse (↑ 15.1-32.5%) these membranes. Theoretical analysis predicted that this membranolytic mechanism involved a tilted segment, that increased along the α-helical long axis of E2EM-lin (1-23) in the N → C direction, with -  < µH > increasing overall from circa - 0.8 to - 0.3. In combination, these data showed that E2EM-lin killed bacteria via novel mechanisms that were enhanced by alkaline conditions and involved the formation of tilted and membranolytic, α-helical structure. The preference of E2EM-lin for Gram-positive bacteria over Gram-negative organisms was primarily driven by the superior ability of phosphatidylglycerol to induce α-helical structure in the peptide as compared to phosphatidylethanolamine. These data were used to generate a novel pore-forming model for the membranolytic activity of E2EM-lin, which would appear to be the first, major reported instance of pH dependent AMPs with alkaline optima using tilted structure to drive a pore-forming process. It is proposed that E2EM-lin has the potential for development to serve purposes ranging from therapeutic usage, such as chronic wound disinfection, to food preservation by killing food spoilage organisms.

Harnessing the physicochemical properties of DNA as a multifunctional biomaterial for biomedical and other applications

The biological purpose of DNA is to store, replicate, and convey genetic information in cells. Progress in molecular genetics have led to its widespread applications in gene editing, gene therapy, and forensic science. However, in addition to its role as a genetic material, DNA has also emerged as a nongenetic, generic material for diverse biomedical applications. DNA is essentially a natural biopolymer that can be precisely programed by simple chemical modifications to construct materials with desired mechanical, biological, and structural properties. This review critically deciphers the chemical tools and strategies that are currently being employed to harness the nongenetic functions of DNA. Here, the primary product of interest has been crosslinked, hydrated polymers, or hydrogels. State-of-the-art applications of macroscopic, DNA-based hydrogels in the fields of environment, electrochemistry, biologics delivery, and regenerative therapy have been extensively reviewed. Additionally, the review encompasses the status of DNA as a clinically and commercially viable material and provides insight into future possibilities.

A novel homozygous nonsense mutation in the CA2 gene (c.368G>A, p.W123X) linked to carbonic anhydrase II deficiency syndrome in a Chinese family

BACKGROUND

Carbonic anhydrase II deficiency syndrome is an autosomal recessive osteopetrosis with renal tubular acidosis and cerebral calcifications. We tried to detect the causative mutation for carbonic anhydrase II deficiency syndrome in a five-generation Chinese family.

MATERIALS AND METHODS

Genomic DNA was extracted from whole blood of the proband, his grandmother, parents, aunt, uncle and sister. The exomes were sequenced by whole exon sequencing followed by genetic analysis and Sanger sequencing validation. Then, physical and chemical properties studies and structure analysis were performed on mutated protein. Finally, Minigene model of vector plasmids for wild type and mutant type was constructed and transfected into human embryonic kidney 293T cells to further explore the expression change of CA2 transcript and protein after mutation.

RESULTS

Sequencing and genetic analysis have revealed the homozygous nonsense mutation of CA2 gene (c.368G > A, p.W123X) in the exon 4 of chromosome 8 of the proband, while it was not found in his grandmother, parents, aunt, uncle and sister. Furthermore, Sanger sequencing in the proband and his parents validated the mutation. Properties and structure of mutated CA2 proteins changed after mutation, especially in change of protein modification and hindrance of zinc ions binding, which may lead to decreased protein expression level of CA2.

CONCLUSIONS

We found a new homozygous nonsense mutation in CA2 gene (c.368G > A, p.W123X), which may be valuable in the early diagnosis and therapy of carbonic anhydrase II deficiency syndrome.

Aqueous Tuber Extracts of Tylosema fassoglense (Kotschy ex Schweinf.) Torre and Hillc. (Fabaceae). Possess Significant In-Vivo Antidiarrheal Activity and Ex-Vivo Spasmolytic Effect Possibly Mediated by Modulation of Nitrous Oxide System, Voltage-Gated Calcium Channels, and Muscarinic Receptors

Tylosema fassoglense (TFG) is used as an antidiarrheal traditional medicine in Western Kenya. This study aimed to investigate the antidiarrheal activity of its aqueous extracts in-vivo and the putative mechanism (s) of action ex-vivo using Sprague-Dawley rats and New Zealand white rabbits respectively. The in-vivo antidiarrheal effects of the extract were evaluated in castor oil-induced diarrhea, the castor oil-induced enteropooling, and phenol red gastric motility tests. On the other hand, isolated rabbit's jejunal segments were used to evaluate the spasmolytic effect of TFG on spontaneous contraction, in acetylcholine-induced contraction, in presence of 80mMK⁺, calcium chloride-induced contraction as well as in presence of the following antagonists: naloxone, methylene blue, L-NAME, prazosin, and propranolol in the ex-vivo studies. The data were express as Mean ± S.E.M and analyzed by one-way ANOVA and Tukey's post hoc test in cases of significance which was set at p < 0.05. The extract was phytochemically characterized using Liquid chromatography Mass spectroscopy (LC-MS).The extract possessed significant inhibitory effect in the in-vivo experiments. The extract exhibited significant spasmolytic effect on both spontaneous contraction and in jejunal segment pre-contracted acetylcholine as well as in presence of 80mMK⁺ solution. It also attenuated the spasmogenic effect of various concentration of calcium chloride. The extract's spasmolytic effect was, however, significantly attenuated in presence of several antagonists (methylene blue and L-NAME) but the adrenergic blockers (prazosin and propranolol) had no significant effect in the ex-vivo studies. LC-MS identified thirty compounds where Proathocyanidin (11.54%), Syringic acid (7.30%), and 4-Hydroxybenzoic acid (6.19%) had the highest percentage abundance. In conclusion, the results obtained in this study partially validate the traditional uses of the tubers of this plant species as an antidiarrheal. These antidiarrheal effects are probably mediated via modulation of nitrous oxide pathway, voltage gated calcium channels, and muscarinic receptors.

Hypochloremia Secondary to Diuretics in Preterm Infants: Should Clinicians Pay Close Attention?

Diuretic therapy, commonly used in the newborn intensive care unit, is associated with a variety of electrolyte abnormalities such as hyponatremia, hypokalemia, and hypochloremia. Hypochloremia, often ignored, is associated with significant morbidities and increased mortality in infants and adults. Clinicians respond in a reflex manner to hyponatremia than to hypochloremia. Hypochloremia is associated with nephrocalcinosis, hypochloremic alkalosis, and poor growth. Besides, the diuretic resistance associated with hypochloremia makes maintaining chloride levels in the physiological range even more logical. Since sodium supplementation counters the renal absorption of calcium and lack of evidence for spironolactone role in diuretic therapy for bronchopulmonary dysplasia (BPD), alternate chloride supplements such as potassium or arginine chloride may need to be considered in the management of hypochloremia due to diuretic therapy. In this review, we have summarized the current literature on hypochloremia secondary to diuretics and suggested a pragmatic approach to hypochloremia in preterm infants.

Effects and interaction of dietary electrolyte balance and citric acid on growth performance, intestinal histomorphology, digestive enzyme activity and nutrient transporters expression of weaned piglets

Fifty-six piglets were weaned at 21 days and randomly assigned to 1 of 8 dietary treatments with 7 replicate pens for a 14-day experimental period. The eight experimental diets were prepared via a 2 × 4 factorial arrangement with citric acid (CA; 0 and 0.3%) and dietary electrolyte balance (dEB, Na +K - Cl mEq/kg of the diet; -50, 100, 250, and 400 mEq/kg). Varying dEB values were obtained by altering calcium chloride and sodium bicarbonate contents. Dietary CA significantly increased (p < .05) villus height (VH) and villus height:crypt depth (VH:CD) in the jejunum. Piglets fed a 250 mEq/kg diet increased (p < .05) VH and VH:CD values in the duodenum. Jejunal VH and VH:CD increased (quadratic; p < .05), and ileal VH:CD (liner and quadratic; p < .05) decreased as dEB was increased in diets without CA, but no such effect was observed on the diets containing CA (dEB ×CA; p < .05). The CD in jejunum (quadratic; p < .05) increased as dEB was increased in diets containing CA, whereas it was decreased (linear; p < .05) in the diets without CA (dEB ×CA; p < .001). Dietary CA increased maltase activity and reduced the number of Ki67-positive cells (p < .05). Increasing dEB values in diets without CA increased sucrose and lactase activities (quadratic; p < .05), but no such effect was observed in the diets with CA (dEB ×CA; p < .05). An interaction effect between dEB and CA on the number of Ki67-positive cells was observed (p < .001). In conclusion, 250 mEq/kg dEB diet with CA improved piglet intestinal digestion and absorption function by improving intestinal morphology and increasing digestive enzyme activities. However, these improvements were also observed in piglets fed the 100 mEq/kg dEB diet without CA.

Mouse Lung Structure and Function after Long-Term Exposure to an Atmospheric Carbon Dioxide Level Predicted by Climate Change Modeling

BACKGROUND

Climate change models predict that atmospheric carbon dioxide [CO2] levels will be between 700 and 900 ppm within the next 80 y. Despite this, the direct physiological effects of exposure to slightly elevated atmospheric CO2 (as compared with ∼410 ppm experienced today), especially when exposures extend from preconception to adulthood, have not been thoroughly studied.

OBJECTIVES

In this study we aimed to assess the respiratory structure and function effects of long-term exposure to 890 ppm CO2 from preconception to adulthood using a mouse model.

METHODS

We exposed mice to CO2 (∼890 ppm) from prepregnancy, through the in utero and early life periods, until 3 months of age, at which point we assessed respiratory function using the forced oscillation technique, and lung structure.

RESULTS

CO2 exposure resulted in a range of respiratory impairments, particularly in female mice, including higher tissue elastance, longer chord length, and lower lung compliance. Importantly, we also assessed the lung function of the dams that gave birth to our experimental subjects. Even though these mice had been exposed to the same level of increased CO2 for a similar amount of time (∼8wk), we measured no impairments in lung function. This suggests that the early life period, when lungs are undergoing rapid growth and development, is particularly sensitive to CO2.

DISCUSSION

To the best of our knowledge, this study, for the first time, shows that long-term exposure to environmentally relevant levels of CO2 can impact respiratory function in the mouse. https://doi.org/10.1289/EHP7305.

The Biology of Physiological Health

The ability to maintain health, or recover to a healthy state after disease, is an active process involving distinct adaptation mechanisms coordinating interactions between all physiological systems of an organism. Studies over the past several decades have assumed the mechanisms of health and disease are essentially inter-changeable, focusing on the elucidation of the mechanisms of disease pathogenesis to enhance health, treat disease, and increase healthspan. Here, I propose that the evolved mechanisms of health are distinct from disease pathogenesis mechanisms and suggest that we develop an understanding of the biology of physiological health. In this Perspective, I provide a definition of, a conceptual framework for, and proposed mechanisms of physiological health to complement our understanding of disease and its treatment.

Physiological Effects of Low Salinity Exposure on Bottlenose Dolphins (Tursiops truncatus)

Bottlenose dolphins (Tursiops truncatus) have a worldwide distribution in temperate and tropical waters and often inhabit estuarine environments, indicating their ability to maintain homeostasis in low salinity for limited periods of time. Epidermal and biochemical changes associated with low salinity exposure have been documented in stranded bottlenose dolphins; however, these animals are often found severely debilitated or deceased and in poor condition. Dolphins in the U.S. Navy Marine Mammal Program travel globally, navigating varied environments comparable to those in which free-ranging dolphins are observed. A retrospective analysis was performed of medical records from 46 Navy dolphins and blood samples from 43 Navy dolphins exposed to a variety of salinity levels for different durations over 43 years (from 1967–2010). Blood values from samples collected during low salinity environmental exposure (salinity ranging from 0–30 parts per thousand (ppt) were compared to samples collected while those same animals were in a seawater environment (31–35 ppt). Epidermal changes associated with low salinity exposure were also assessed. Significant decreases in serum sodium, chloride, and calculated serum osmolality and significant increases in blood urea nitrogen and aldosterone were observed in blood samples collected during low salinity exposure. Epidermal changes were observed in 35% of the animals that spent time in low salinity waters. The prevalence of epidermal changes was inversely proportional to the level of salinity to which the animals were exposed. Future work is necessary to fully comprehend the impacts of low salinity exposure in bottlenose dolphins, but the physiological changes observed in this study will help improve our understanding of the upper limit of duration and the lower limit of salinity in which a bottlenose dolphin can maintain homeostasis.

Acid-Producing Diet and Depressive Symptoms among Breast Cancer Survivors: A Longitudinal Study

Simple Summary

Depressive symptoms, which are highly prevalent among breast cancer survivors, can significantly influence quality of life and increase total mortality. The aim of our prospective study was to determine whether acid-producing diets have an adverse impact on depression. Our study demonstrated that a higher consumption of acid-producing diets was significantly associated with depressive symptoms among breast cancer survivors, especially among those who were younger than 55 and had a sedentary lifestyle.

Abstract

The incidence of depression is two-to-three times higher in cancer survivors than the general population. Acid-producing diets may play important roles in the development of depression. Cancer survivors are more susceptible to acid-producing diets, yet few prospective studies have investigated the association of acid-producing diets with depression among breast cancer survivors. We leveraged a large cohort of 2975 early stage breast cancer survivors, which collected detailed dietary data via 24-h recalls. Potential renal acid load (PRAL) and net endogenous acid production (NEAP), two commonly used dietary acid load scores, were used to estimate acid-producing diets. Intakes of PRAL and NEAP were assessed at baseline and years one and four. Increased PRAL and NEAP were each independently associated with increased depression in the longitudinal analyses, after adjusting for covariates. The magnitude of the associations was stronger for PRAL than NEAP. Women with the highest quartile intakes of PRAL had 1.34 (95% CI 1.11–1.62) times the risk of depression compared to women with the lowest quartile. Furthermore, we also observed a joint impact of PRAL and younger age on depression, as well as a joint impact of PRAL and physical activity on depression. Decreasing the consumption of acid-producing diets may be a novel and practical strategy for reducing depressive symptoms among breast cancer survivors, especially those who are younger and have a sedentary lifestyle.

Physiological Processes Modulated by the Chloride-Sensitive WNK-SPAK/OSR1 Kinase Signaling Pathway and the Cation-Coupled Chloride Cotransporters

The role of Cl- as an intracellular signaling ion has been increasingly recognized in recent years. One of the currently best described roles of Cl- in signaling is the modulation of the With-No-Lysine (K) (WNK) - STE20-Proline Alanine rich Kinase (SPAK)/Oxidative Stress Responsive Kinase 1 (OSR1) - Cation-Coupled Cl- Cotransporters (CCCs) cascade. Binding of a Cl- anion to the active site of WNK kinases directly modulates their activity, promoting their inhibition. WNK activation due to Cl- release from the binding site leads to phosphorylation and activation of SPAK/OSR1, which in turn phosphorylate the CCCs. Phosphorylation by WNKs-SPAK/OSR1 of the Na+-driven CCCs (mediating ions influx) promote their activation, whereas that of the K+-driven CCCs (mediating ions efflux) promote their inhibition. This results in net Cl- influx and feedback inhibition of WNK kinases. A wide variety of alterations to this pathway have been recognized as the cause of several human diseases, with manifestations in different systems. The understanding of WNK kinases as Cl- sensitive proteins has allowed us to better understand the mechanistic details of regulatory processes involved in diverse physiological phenomena that are reviewed here. These include cell volume regulation, potassium sensing and intracellular signaling in the renal distal convoluted tubule, and regulation of the neuronal response to the neurotransmitter GABA.

Urinalysis in dog and cat: A review

Urinalysis is the examination of normal and abnormal constituents of urine. It is an easy, cheap, and vital initial diagnostic test for veterinarians. Complete urinalysis includes the examination of color, odor, turbidity, volume, pH, specific gravity, protein, glucose, ketones, blood, erythrocytes, leukocytes, epithelial cells, casts, crystal, and organisms. Semi-quantitative urine analysis with urine dipsticks, as well as an automatic analyzer, provides multiple biochemical data. Contamination is almost entirely avoided if the protocols for ensuring a proper sample have been followed, as mentioned still consideration must be given to the likelihood of contamination, even if the sample is correctly obtained. Interpretation of urinalysis will be doubtful if the knowledge of the interference is limited. Well-standardized urinalysis, when correlated in the context of history, clinical findings, and other diagnostic test results, can identify both renal and non-renal disease. This paper reviews significance of different components of urinalysis of dog and cat, such as collection, storage, examination, interpretation, and common causes of error in the result.

The Impact of Infection and Inflammation on Drug Metabolism, Active Transport, and Systemic Drug Concentrations in Veterinary Species

Within human medicine, it is recognized that the pharmacokinetics (PK) of many compounds can be altered by the presence of inflammation or infection. Research into the reason for these changes has identified pathways that can influence drug absorption, clearance, and tissue distribution. In contrast, far less is known about these relationships within the framework of veterinary medicine. Rather, most of the PK data generated in veterinary species employs healthy subjects, raising the question of whether these studies are founded on an assumption that healthy animal PK reflect that of the diseased animal population. Accordingly, there is a need to explore the PK changes that might be overlooked in studies that recruit only healthy animals to assesses drug PK. To meet this objective, we surveyed the published literature for studies focusing on the impact of disease on the dose-exposure relationships in food-producing and companion animal species. We found that, consistent with humans and laboratory species, both up- and downregulation of the various cytochrome isoenzymes and/or transporters have occurred in response to an increase in inflammatory mediators. These findings suggest that, as observed in human medicine, the potential for differences in the drug PK in healthy versus animal patients points to a need for acquiring a greater understanding of these changes and how they may influence the dose-exposure-response relationships of veterinary pharmaceuticals. SIGNIFICANCE STATEMENT: This review delivers a much-needed summary of published information that provides insights into how disease and inflammation can influence the appropriateness of extrapolating laboratory-based dose-exposure-response relationships to what will occur in the actual veterinary patient. As part of this review, we also examine some of the method-associated issues to be considered when assessing the reported nature and magnitude of these changes.

Recent advances in nanotechnology-based drug delivery systems for the kidney

The application of nanotechnology in medicine has the potential to make a great impact on human health, ranging from prevention to diagnosis and treatment of disease. The kidneys are the main organ of the human urinary system, responsible for filtering the blood, and concentrating metabolic waste into urine by means of the renal glomerulus. The glomerular filtration apparatus presents a barrier against therapeutic agents based on charge and/or molecular size. Therefore, drug delivery to the kidneys faces significant difficulties resulting in treatment failure in several renal disorders. Accordingly, different strategies have recently being explored for enhancing the delivery of therapeutic agents across the filtration barrier of the glomerulus. Nanosystems with different physicochemical properties, including size, shape, surface, charge, and possessing biological features such as high cellular internalization, low cytotoxicity, controllable pharmacokinetics and biodistribution, have shown promising results for renal therapy. Different types of nanoparticles (NPs) have been used to deliver drugs to the kidney. In this review, we discuss nanotechnology-based drug delivery approaches for acute kidney injury, chronic kidney disease, renal fibrosis, renovascular hypertension and kidney cancer.

Use of lanthanum for water treatment A matter of concern?

Among several other eutrophication management tools, Phoslock®, a lanthanum modified bentonite (LMB) clay, is now frequently used. Concerns have been raised as to whether exposure to Phoslock®-treated water may lead to lanthanum accumulation/toxicity in both animals and humans. In the present experimental study, rats were administered lanthanum orally as either lanthanum carbonate, lanthanum chloride or Phoslock® at doses of either 0.5 or 17 mg/L during 10 weeks. Controls received vehicle. The gastrointestinal absorption and tissue distribution of lanthanum was investigated. Extremely strict measures were implemented to avoid cross-contamination between different tissues or animals. Results showed no differences in gastrointestinal absorption between the different compounds under study as reflected by the serum lanthanum levels and concentrations found in the brain, bone, heart, spleen, lung, kidney and testes. At sacrifice, significant but equally increased lanthanum concentrations versus vehicle were observed in the liver for the highest dose of each compound which however, remained several orders of magnitude below the liver lanthanum concentration previously measured after long-term therapeutic administration of lanthanum carbonate and for which no hepatotoxicity was noticed in humans. In conclusion, (i) the use of LMB does not pose a toxicity risk (ii) gastrointestinal absorption of lanthanum is minimal and independent on the type of the compound, (iii) with exception of the liver, no significant increase in lanthanum levels is observed in the various organs under study, (iv) based on previous studies, the slightly increased liver lanthanum levels observed in a worst case scenario do not hold any risk of hepatotoxicity.

Effects of mineral waters on acid-base status in healthy adults: results of a randomized trial

Background

The ‘Western diet’ typically consumed in industrialized countries is characterized by high amounts of processed cereal grains and animal products while being low in vegetables, tubers, and fruits. This dietary behavior leads to imbalances of acid–base status in favor of the acids and may cause low-grade metabolic acidosis (LGMA) that is associated with negative effects on health in the long run, including urolithiasis, bone loss, and even cardiometabolic diseases. Therefore, it has become of great interest to find dietary strategies that can be used to neutralize the acid load associated with Western diets.

Objective

The aim of this study was to investigate whether the diet-dependent net acid load can be reduced by the daily consumption of mineral waters with different bicarbonate content and different potential renal acid load (PRAL).

Methods

A single-centered, randomized trial including 129 healthy men and women aged from 18 to 75 years was conducted. Participants consumed 1,500–2,000 mL of one of four mineral waters with different bicarbonate content and different PRAL values daily for 4 weeks: low bicarbonate, high PRAL (LBHP, HCO₃⁻: 403.0 mg/L, PRAL: 10.7); medium-high bicarbonate, medium PRAL (MBMP, HCO₃⁻ : 1816.0 mg/L, PRAL: −10.8); high bicarbonate, low PRAL (HBLP, HCO₃⁻: 2451.0 mg/L, PRAL: −19.3); medium-high bicarbonate, low PRAL (MBLP, HCO₃⁻: 1846.0 mg/L, PRAL: −22.1). Throughout the study, participants were asked to maintain their usual dietary habits. The primary outcome was the net acid excretion (NAE) measured in the 24-h urine output.

Results

Consumption of the three mineral waters: MBMP, HBLP, and MBLP led to a significant decrease in NAE values. Within the MBMP group, the NAE could be reduced by 48% (P = 0.001), while consumption of HBLP led to a reduction of 68% (P < 0.001) and MBLP to a reduction of 53% (P = 0.001). Moreover, a slight increase in serum bicarbonate could also be observed in the groups that drank HBLP (P = 0.057) and MBLP (P = 0.001).

Conclusion

Daily consumption of at least 1,500–2,000 mL of mineral water rich in bicarbonate (>1800.0 mg/L) with medium or low PRAL (<−11 mEq/L) can effectively reduce the NAE level by reducing the dietary acid load under free-living conditions in healthy adults.

Mechanism of Action of Non-Synonymous Single Nucleotide Variations Associated with α-Carbonic Anhydrase II Deficiency

Human carbonic anhydrase II (CA-II) is a Zinc (Zn 2 + ) metalloenzyme responsible for maintenance of acid-base balance within the body through the reversible hydration of CO 2 to produce protons (H + ) and bicarbonate (BCT). Due to its importance, alterations to the amino acid sequence of the protein as a result of single nucleotide variations (nsSNVs) have detrimental effects on homeostasis. Six pathogenic CA-II nsSNVs, K18E, K18Q, H107Y, P236H, P236R and N252D were identified, and variant protein models calculated using homology modeling. The effect of each nsSNV was analyzed using motif analysis, molecular dynamics (MD) simulations, principal component (PCA) and dynamic residue network (DRN) analysis. Motif analysis identified 11 functionally important motifs in CA-II. RMSD data indicated subtle SNV effects, while PCA analysis revealed that the presence of BCT results in greater conformational sampling and free energy in proteins. DRN analysis showed variant allosteric effects, and the average betweenness centrality (BC) calculations identified Glu117 as the most important residue for communication in CA-II. The presence of BCT was associated with a reduction to Glu117 usage in all variants, suggesting implications for Zn 2 + dissociation from the CA-II active site. In addition, reductions to Glu117 usage are associated with increases in the usage of the primary and secondary Zn 2 + ligands; His94, His96, His119 and Asn243 highlighting potential compensatory mechanisms to maintain Zn 2 + within the active site. Compared to traditional MD simulation investigation, DRN analysis provided greater insights into SNV mechanism of action, indicating its importance for the study of missense mutation effects in proteins and, in broader terms, precision medicine related research.

Nucleolus vs Nucleus Count for Identifying Spiral Ganglion in Human Temporal Bone

OBJECTIVES

Spiral ganglion (SG) counting is used in experimental studies conducted on age-, noise-, and drug-induced sensorineural hearing loss, as well as in the assessment of cochlear implant performances. Different methods of counting have been reported, but no definite standardization of such procedure has been published. The aim of our study is to identify the best method to count human spiral ganglions (SGs).

MATERIALS AND METHODS

By identification of nuclei or nucleoli as described by Schucknect, seven researchers with different experience levels counted SGs in 123 human temporal bones (TBs). Data on time of post-mortem bone removal post-mortem, methods of specimen's fixation, decalcification, and coloration were collected to test their possible influence on human tissue. Percentage, two-tailed t-test, Spearman's test, and one-way ANOVA were used to analyze the data.

RESULTS

Nucleoli were identified in 61% of cases, whereas nuclei were recognized in 100% of cases (p<0.005). Nucleoli presence in all four segments in the same temporal bone (TB) was observed in 69 cases (92%), whereas nuclei were identified in all four segments in 103 cases (83.7%) (p<0.001). The junior investigators requested a double check by the seniors in 25 (20.3%) cases for identifying and counting nucleoli, whereas the senior researchers showed no doubts in their identification and count. The only parameter positively affecting nucleoli identification in tissue preparation was bone removal for <12 h with respect to longer post-mortem time (p<0.001).

CONCLUSION

We suggest counting nuclei, rather than nucleoli, for spiral ganglion computation because of easier recognition of nuclei, especially in case of investigator's limited experience.

Adenylyl cyclase 6 in acid-base balance - adding complexity

Systemic acid-base balance is tightly controlled within a narrow range of pH. Disturbances in systemic acid-base homeostasis are associated with diverse detrimental effects. The kidney is a key regulator of acid-base balance, capable of excreting HCO₃^- or H⁺, and chronic kidney disease invariably leads to acidosis. However, the regulatory pathways underlying the fine-tuned acid-base sensing and regulatory mechanisms are still incompletely understood. In the article published recently in Clinical Science (vol 132 (16) 1779-1796), Poulson and colleagues investigated the role of adenylyl cyclase 6 (AC6) in acid-base homeostasis. They uncovered a complex role of AC6, specifically affecting acid-base balance during HCO₃^- load, which causes pronounced alkalosis in AC6-deficient mice. However, the phenotype of AC6-deficient mice appears much more complex, involving systemic effects associated with increased energy expenditure. These observations remind us that there is much to be learned about the intricate signaling pathways involved in renal control of acid-base balance and the complex ramifications of acid-base regulation.

Hypokalemia: a clinical update

Hypokalemia is a common electrolyte disturbance, especially in hospitalized patients. It can have various causes, including endocrine ones. Sometimes, hypokalemia requires urgent medical attention. The aim of this review is to present updated information regarding: (1) the definition and prevalence of hypokalemia, (2) the physiology of potassium homeostasis, (3) the various causes leading to hypokalemia, (4) the diagnostic steps for the assessment of hypokalemia and (5) the appropriate treatment of hypokalemia depending on the cause. Practical algorithms for the optimal diagnostic, treatment and follow-up strategy are presented, while an individualized approach is emphasized.