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Systemic acid-base status is primarily determined by the interplay of net acid production (NEAP) arising from metabolism of ingested food stuffs, buffering of NEAP in tissues, generation of bicarbonate by the kidney, and capture of any bicarbonate filtered by the kidney. In chronic kidney disease (CKD), acid retention may occur when dietary acid production is not balanced by bicarbonate generation by the diseased kidney. Hormones including aldosterone, angiotensin II, endothelin, PTH, glucocorticoids, insulin, thyroid hormone, and growth hormone can affect acid-base balance in different ways. The levels of some hormones such as aldosterone, angiotensin II and endothelin are increased with acid accumulation and contribute to an adaptive increase in renal acid excretion and bicarbonate generation. However, the persistent elevated levels of these hormones can damage the kidney and accelerate progression of CKD. Measures to slow the progression of CKD have included administration of medications which inhibit the production or action of deleterious hormones. However, since metabolic acidosis accompanying CKD stimulates the secretion of several of these hormones, treatment of CKD should also include administration of base to correct the metabolic acidosis.

Solid tumors such as prostate cancer (PCa) commonly develop an acidic microenvironment with pH 6.5-7.2, owing to heterogeneous perfusion, high metabolic activity, and rapid cell proliferation. In preclinical prostate cancer models, disease progression is associated with a decrease in tumor extracellular pH, suggesting that pH imaging may reflect an imaging biomarker to detect aggressive and high-risk disease. Therefore, we developed a hyperpolarized carbon-13 MRI method to image the tumor extracellular pH (pHe) and prepared it for clinical translation for detection and risk stratification of PCa. This method relies on the rapid breakdown of hyperpolarized (HP) 1,2-glycerol carbonate (carbonyl-13C) via base-catalyzed hydrolysis to produce HP 13CO32-, which is neutralized and converted to HP H13CO3-. After injection, HP H13CO3- equilibrates with HP 13CO2 in vivo and enables the imaging of pHe. Using insights gleaned from mechanistic studies performed in the hyperpolarized state, we solved issues of polarization loss during preparation in a clinical polarizer system. We successfully customized a reaction apparatus suitable for clinical application, developed clinical standard operating procedures, and validated the radiofrequency pulse sequence and imaging data acquisition with a wide range of animal models. The results demonstrated that we can routinely produce a highly polarized and safe HP H13CO3- contrast agent suitable for human injection. Preclinical imaging studies validated the reliability and accuracy of measuring acidification in healthy kidney and prostate tumor tissue. These methods were used to support an Investigational New Drug application to the U.S. Food and Drug Administration. This methodology is now ready to be implemented in human trials, with the ultimate goal of improving the management of PCa.

13C-bicarbonate is a crucial measure of pyruvate oxidation and TCA cycle flux, but is challenging to measure due to its relatively low concentration and thus will greatly benefit from improved signal-to-noise ratio (SNR). To address this, we developed and investigated the feasibility of a 3D stack-of-spirals metabolite-specific balanced steady-state free precession (MS-bSSFP) sequence for improving the SNR and spatial resolution of dynamic 13C-bicarbonate imaging in hyperpolarized [1-13C]pyruvate studies. The bicarbonate MS-bSSFP sequence was evaluated by simulations, phantoms studies, preclinical studies on five rats, brain studies on two healthy volunteers and renal study on one renal cell carcinoma patient. The simulations and phantom results showed that the bicarbonate-specific pulse had minimal perturbation of other metabolites (

BackgroundThe use of sodium bicarbonate to treat metabolic acidosis is intuitive, yet data suggest that not all patients benefit from this therapy.ObjectiveIn this narrative review, we describe the physiology behind commonly encountered nontoxicologic causes of metabolic acidosis, highlight potential harm from the indiscriminate administration of sodium bicarbonate in certain scenarios, and provide evidence-based recommendations to assist emergency physicians in the rational use of sodium bicarbonate.DiscussionSodium bicarbonate can be administered as a hypertonic push, as a resuscitation fluid, or as an infusion. Lactic acidosis and cardiac arrest are two common scenarios where there is limited benefit to routine use of sodium bicarbonate, although certain circumstances, such as patients with concomitant acute kidney injury and lactic acidosis may benefit from sodium bicarbonate. Patients with cardiac arrest secondary to sodium channel blockade or hyperkalemia also benefit from sodium bicarbonate therapy. Recent data suggest that the use of sodium bicarbonate in diabetic ketoacidosis does not confer improved patient outcomes and may cause harm in pediatric patients. Available evidence suggests that alkalinization of urine in rhabdomyolysis does not improve patient-centered outcomes. Finally, patients with a nongap acidosis benefit from sodium bicarbonate supplementation.ConclusionsEmpiric use of sodium bicarbonate in patients with nontoxicologic causes of metabolic acidosis is not warranted and likely does not improve patient-centered outcomes, except in select scenarios. Emergency physicians should reserve use of this medication to conditions with clear benefit to patients.

BackgroundThe heart has metabolic flexibility, which is influenced by fed/fasting states, and pathologies such as myocardial ischemia and hypertrophic cardiomyopathy (HCM). Hyperpolarized (HP) 13C-pyruvate MRI is a promising new tool for non-invasive quantification of myocardial glycolytic and Krebs cycle flux. However, human studies of HP 13C-MRI have yet to demonstrate regional quantification of metabolism, which is important in regional ischemia and HCM patients with asymmetric septal/apical hypertrophy.MethodsWe developed and applied methods for whole-heart imaging of 13C-pyruvate, 13C-lactate and 13C-bicarbonate, following intravenous administration of [1-13C]-pyruvate. The image acquisition used an autonomous scanning method including bolus tracking, real-time magnetic field calibrations and metabolite-specific imaging. For quantification of metabolism, we evaluated 13C metabolite images, ratio metrics, and pharmacokinetic modeling to provide measurements of myocardial lactate dehydrogenase (LDH) and pyruvate dehydrogenase (PDH) mediated metabolic conversion in 5 healthy volunteers (fasting & 30 min following oral glucose load).ResultsWe demonstrate whole heart coverage for dynamic measurement of pyruvate-to-lactate conversion via LDH and pyruvate-to-bicarbonate conversion via PDH at a resolution of 6 × 6 × 21 mm3 (13C-pyruvate) and 12 × 12 × 21 mm3 (13C-lactate, 13C-bicarbonate). 13C-pyruvate and 13C-lactate were detected simultaneously in the RV blood pool, immediately after intravenous injection, reflecting LDH activity in blood. In healthy volunteers, myocardial 13C-pyruvate-SNR, 13C-lactate-SNR, 13C-bicarbonate-SNR, 13C-lactate/pyruvate ratio, 13C-pyruvate-to-lactate conversion rate, kPL, and 13C-pyruvate-to-bicarbonate conversion rate, kPB, all had statistically significant increases following oral glucose challenge. kPB, reflecting PDH activity and pyruvate entering the Krebs Cycle, had the highest correlation with blood glucose levels and was statistically significant.ConclusionsWe demonstrate first-in-human regional quantifications of cardiac metabolism by HP 13C-pyruvate MRI that aims to reflect LDH and PDH activity.

BackgroundDynamic hyperpolarized (HP)-13C MRI has enabled real-time, non-invasive assessment of Warburg-related metabolic dysregulation in glioma using a [1-13C]pyruvate tracer that undergoes conversion to [1-13C]lactate and [13C]bicarbonate. Using a multi-parametric 1H/HP-13C imaging approach, we investigated dynamic and steady-state metabolism, together with physiological parameters, in high-grade gliomas to characterize active tumor.MethodsMulti-parametric 1H/HP-13C MRI data were acquired from fifteen patients with progressive/treatment-naïve glioblastoma [prog/TN GBM, IDH-wildtype (n = 11)], progressive astrocytoma, IDH-mutant, grade 4 (G4AIDH+, n = 2) and GBM manifesting treatment effects (n = 2). Voxel-wise regional analysis of the cohort with prog/TN GBM assessed imaging heterogeneity across contrast-enhancing/non-enhancing lesions (CEL/NEL) and normal-appearing white matter (NAWM) using a mixed effects model. To enable cross-nucleus parameter association, normalized perfusion, diffusion, and dynamic/steady-state (HP-13C/spectroscopic) metabolic data were collectively examined at the 13C resolution. Prog/TN GBM were similarly compared against progressive G4AIDH+ and treatment effects.ResultsRegional analysis of Prog/TN GBM metabolism revealed statistically significant heterogeneity in 1H choline-to-N-acetylaspartate index (CNI)max, [1-13C]lactate, modified [1-13C]lactate-to-[1-13C]pyruvate ratio (CELval > NELval > NAWMval); [1-13C]lactate-to-[13C]bicarbonate ratio (CELval > NELval/NAWMval); and 1H-lactate (CELval/NELval > NAWMundetected). Significant associations were found between normalized perfusion (cerebral blood volume, nCBV; peak height, nPH) and levels of [1-13C]pyruvate and [1-13C]lactate, as well as between CNImax and levels of [1-13C]pyruvate, [1-13C]lactate and modified ratio. GBM, by comparison to G4AIDH+, displayed lower perfusion %-recovery and modeled rate constants for [1-13C]pyruvate-to-[1-13C]lactate conversion (kPL), and higher 1H-lactate and [1-13C]pyruvate levels, while having higher nCBV, %-recovery, kPL, [1-13C]pyruvate-to-[1-13C]lactate and modified ratios relative to treatment effects.ConclusionsGBM consistently displayed aberrant, Warburg-related metabolism and regional heterogeneity detectable by novel HP-13C/1H imaging techniques.

Natural Mg phyllosilicates are potential sources of divalent cations, which are necessary for the mineralization of CO2 into carbonates. The influence of inorganic () and organic (oxalate and citrate) ligands on the dissolution kinetics of talc and serpentine was studied in experiments in a flow-through reactor at 25°C. The dissolution rates of natural silicates r (mol cm–2 s–1) in solutions of various composition were calculated at the stationary stage of dissolution after a rapid initial stage, which is characterized by the formation of a surface leached layer depleted in magnesium. The presence of ligands increases the dissolution rate of magnesium silicates due to the formation of surface complexes, which leads to magnesium separation from the surface and transfer into solution. The initial incongruent stage may be the most promising for the development of carbonation technologies, because the minimum removal of the network-forming elements prevents the undesirable formation of secondary minerals (for example, clays), which exclude divalent cations from the carbonation process and greatly reduce the permeability of rocks. [ABSTRACT FROM AUTHOR]

End-tidal CO 2 is used to monitor the ventilation status or hemodynamic efficacy during mechanical ventilation or cardiopulmonary resuscitation (CPR), and it may be affected by various factors including sodium bicarbonate administration. This study investigated changes in end-tidal CO2 after sodium bicarbonate administration. This single-center, prospective observational study included adult patients who received sodium bicarbonate during mechanical ventilation or CPR. End-tidal CO 2 elevation was defined as an increase of ≥20% from the baseline end-tidal CO 2 value. The time to initial increase (lag time, T lag), time to peak (T peak), and duration of the end-tidal CO 2 rise (T duration) were compared between the patients with spontaneous circulation (SC group) and those with ongoing resuscitation (CPR group). Thirty-three patients, (SC group, n = 25; CPR group, n = 8), were included. Compared with the baseline value, the median values of peak end-tidal CO 2 after sodium bicarbonate injection increased by 100% (from 21 to 41 mmHg) in all patients, 89.5% (from 21 to 39 mmHg) in the SC group, and 160.2% (from 15 to 41 mmHg) in the CPR group. The median T lag was 17 s (IQR: 12–21) and the median T peak was 35 s (IQR: 27–52). The median T duration was 420 s (IQR: 90–639). The median T lag , T peak , and T duration were not significantly different between the groups. T duration was associated with the amount of sodium bicarbonate for SC group (correlation coefficient: 0.531, p = 0.006). The administration of sodium bicarbonate may lead to a substantial increase in end-tidal CO 2 for several minutes in patients with spontaneous circulation and in patients with ongoing CPR. After intravenous administration of sodium bicarbonate, the use of end-tidal CO 2 pressure as a physiological indicator may be limited. [ABSTRACT FROM AUTHOR]

PurposeWe constructed a 13C/31P surface coil at 3 T for studying cancer metabolism and bioenergetics. In a single scan session, hyperpolarized 13C-pyruvate MRS and 31P MRS was carried out for a healthy rat brain.MethodsAll experiments were carried out at 3 Tesla. The multinuclear surface coil was designed as two coplanar loops each tuned to either the 13C or 31P operating frequency with an LCC trap on the 13C loop. A commercial volume proton coil was used for anatomical localization and B0 shimming. Single tuned coils operating at either the 13C or 31P frequency were built to evaluate the relative performance of the multinuclear coil. Coil performance metrics consisted of measuring Q factor ratio, calculating system input power using a single-pulse acquisition, and acquiring SNR and flip angle maps using 2D CSI sequences. To observe in vivo spectra, a bolus of hyperpolarized [1-13C] pyruvate was administered via tail vein. In vivo13C and endogenous 31P spectra were obtained in a single scan session using 1D slice selective acquisitions.ResultsWhen compared with single tuned surface coils, the multinuclear coil performance showed a decrease in Q factor ratio, SNR, and transmit efficiency. Flip angle maps showed adequate flip angles within the phantom when the transmit voltage was set using an external phantom. Results show good detection of 13C labeled lactate, alanine, and bicarbonate in addition to ATP from 31P MRS.ConclusionsThe coil enables obtaining complementary information within a scan session, thus reducing the number of trials and minimizing biological variability for studies of metabolism and bioenergetics.

AIMS: To determine the effect of TTP399, a hepatoselective glucokinase activator, on the risk of ketoacidosis during insulin withdrawal in individuals with type 1 diabetes (T1D). MATERIALS AND METHODS: Twenty-three participants with T1D using insulin pump therapy were randomized to 800 mg TTP399 (n = 12) or placebo (n = 11) for 7 to 10 days. After the treatment period, an insulin withdrawal test (IWT) was performed, during which insulin pumps were removed to induce ketogenesis. The IWT was stopped after 10 hours or if blood glucose reached >399 mg/dL [22.1 mmol/L], if beta-hydroxybutyrate (BHB) was >3.0 mmol/L, or for patient discomfort. The primary endpoint was the proportion of participants who reached BHB concentrations of 1 mmol/L or greater. RESULTS: During the 7- to 10-day treatment period, mean fasting plasma glucose was significantly reduced ( -27.6 vs. -4.4 mg/dL [-1.5 vs. -0.2 mmol/L]; P = 0.03) and there were fewer adverse events, including hypoglycaemia, in the TTP399-treated arm. During the IWT, no differences were observed between TTP399 and placebo in mean serum BHB concentration, mean duration of IWT, or BHB at termination of IWT. However, serum bicarbonate was numerically higher and urine acetoacetate was quantitatively lower in the TTP399-treated participants. As a result of higher bicarbonate values, none of the TTP399-treated participants met the prespecified criteria for diabetic ketoacidosis (DKA), defined as BHB >3 mmol/L and serum bicarbonate

Bicarbonate-based electrolytes are ubiquitous in aqueous electrochemical CO2 reduction, particularly in heterogenous catalysis, where they demonstrate improved catalytic performance relative to other buffers. In contrast, the presence of bicarbonate in organic electrolytes and its roles in homogeneous electrocatalysis remain underexplored. Here, we investigate the influence of bicarbonate on iron porphyrin-catalyzed electrochemical CO2 reduction. We show that bicarbonate is a viable proton donor in organic electrolyte (pKa = 20.8 in dimethyl sulfoxide) and that urea pendants in the second coordination sphere can be used to template bicarbonate in the vicinity of a molecular iron porphyrin catalyst. The templated binding of bicarbonate increases its acidity, resulting in a 1500-fold enhancement in catalytic rates relative to unmodified parent iron porphyrin. This work emphasizes the importance of bicarbonate speciation in wet organic electrolytes and establishes second-sphere bicarbonate templating as a design strategy to harness this adventitious acid and enhance CO2 reduction catalysis.

PurposePatients with obesity and elevated serum bicarbonate suggesting obesity hypoventilation syndrome (OHS) undergoing bariatric surgery may represent a unique subgroup. Information regarding surgical outcomes in this population remains limited. We sought to test the hypothesis that an elevated bicarbonate would be an important predictor of perioperative complications (i.e., length of hospital stay) and postsurgical outcomes (i.e., weight loss at 1 year).Materials and methodsConsecutive patients undergoing bariatric surgery between January 2015 and December 2018 were included. Patients with a preoperative serum bicarbonate ≥ 27 mEq/L were classified as suspected OHS.ResultsOf 297 patients, the prevalence of suspected OHS based on an elevated bicarbonate was 19.5% (95% CI: 15.3 to 24.6%). Length of hospital stay was similar in the suspected OHS and non-OHS control group (1.50 vs 1.49 days, P = 0.98). The achieved weight loss from peak preoperative weight to 1 year post-surgery was less in the suspected OHS vs the control group (4.2% [95% CI 1.6 to 6.8]; P = 0.002).ConclusionPatients with serum bicarbonate ≥ 27 mEq/L as a surrogate marker for OHS experienced weight loss that was significantly less than their normal serum bicarbonate counterparts, but still achieved weight loss deemed clinically important by current guidelines. We observed no significant difference in length of hospital stay at time of surgery.

BackgroundReal-time metabolic conversion of intravenously-injected hyperpolarized [1-13C]pyruvate to [1-13C]lactate and [13C]bicarbonate in the brain can be measured using dynamic hyperpolarized carbon-13 (HP-13C) MRI. However, voxel-wise evaluation of metabolism in patients with glioma is challenged by the limited signal-to-noise ratio (SNR) of downstream 13C metabolites, especially within lesions. The purpose of this study was to evaluate the ability of higher-order singular value decomposition (HOSVD) denoising methods to enhance dynamic HP [1-13C]pyruvate MRI data acquired from patients with glioma.MethodsDynamic HP-13C MRI were acquired from 14 patients with glioma. The effects of two HOSVD denoising techniques, tensor rank truncation-image enhancement (TRI) and global-local HOSVD (GL-HOSVD), on the SNR and kinetic modeling were analyzed in [1-13C]lactate data with simulated noise that matched the levels of [13C]bicarbonate signals. Both methods were then evaluated in patient data based on their ability to improve [1-13C]pyruvate, [1-13C]lactate and [13C]bicarbonate SNR. The effects of denoising on voxel-wise kinetic modeling of kPL and kPB was also evaluated. The number of voxels with reliable kinetic modeling of pyruvate-to-lactate (kPL) and pyruvate-to-bicarbonate (kPB) conversion rates within regions of interest (ROIs) before and after denoising was then compared.ResultsBoth denoising methods improved metabolite SNR and regional signal coverage. In patient data, the average increase in peak dynamic metabolite SNR was 2-fold using TRI and 4-5 folds using GL-HOSVD denoising compared to acquired data. Denoising reduced kPL modeling errors from a native average of 23% to 16% (TRI) and 15% (GL-HOSVD); and kPB error from 42% to 34% (TRI) and 37% (GL-HOSVD) (values were averaged voxelwise over all datasets). In contrast-enhancing lesions, the average number of voxels demonstrating within-tolerance kPL modeling error relative to the total voxels increased from 48% in the original data to 84% (TRI) and 90% (GL-HOSVD), while the number of voxels showing within-tolerance kPB modeling error increased from 0% to 15% (TRI) and 8% (GL-HOSVD).ConclusionPost-processing denoising methods significantly improved the SNR of dynamic HP-13C imaging data, resulting in a greater number of voxels satisfying minimum SNR criteria and maximum kinetic modeling errors in tumor lesions. This enhancement can aid in the voxel-wise analysis of HP-13C data and thereby improve monitoring of metabolic changes in patients with glioma following treatment.

Background Pyruvate dehydrogenase (PDH) and lactate dehydrogenase are essential for adenosine triphosphate production in skeletal muscle. At the onset of exercise, oxidation of glucose and glycogen is quickly enabled by dephosphorylation of PDH. However, direct measurement of PDH flux in exercising human muscle is daunting, and the net effect of covalent modification and other control mechanisms on PDH flux has not been assessed. Purpose To demonstrate the feasibility of assessing PDH activation and changes in pyruvate metabolism in human skeletal muscle after the onset of exercise using carbon 13 (13C) MRI with hyperpolarized (HP) [1-13C]-pyruvate. Materials and Methods For this prospective study, sedentary adults in good general health (mean age, 42 years ± 18 [standard deviation]; six men) were recruited from August 2019 to September 2020. Subgroups of the participants were injected with HP [1-13C]-pyruvate at resting, during plantar flexion exercise, or 5 minutes after exercise during recovery. In parallel, hydrogen 1 arterial spin labeling MRI was performed to estimate muscle tissue perfusion. An unpaired t test was used for comparing 13C data among the states. Results At rest, HP [1-13C]-lactate and [1-13C]-alanine were detected in calf muscle, but [13C]-bicarbonate was negligible. During moderate flexion-extension exercise, total HP 13C signals (tC) increased 2.8-fold because of increased muscle perfusion (P = .005), and HP [1-13C]-lactate-to-tC ratio increased 1.7-fold (P = .04). HP [13C]-bicarbonate-to-tC ratio increased 8.4-fold (P = .002) and returned to the resting level 5 minutes after exercise, whereas the lactate-to-tC ratio continued to increase to 2.3-fold as compared with resting (P = .008). Conclusion Lactate and bicarbonate production from hyperpolarized (HP) [1-carbon 13 {13C}]-pyruvate in skeletal muscle rapidly reflected the onset and the termination of exercise. These results demonstrate the feasibility of imaging skeletal muscle metabolism using HP [1-13C]-pyruvate MRI and the sensitivity of in vivo pyruvate metabolism to exercise states. © RSNA, 2021 Online supplemental material is available for this article.

Computational studies with ωB97X-D density functional theory of the mechanisms of the steps in Trauners biomimetic synthesis of preuisolactone A have elaborated and refined mechanisms of several unique processes. An ambimodal transition state has been identified for the cycloaddition between an o-quinone and a hydroxy-o-quinone; this leads to both (5 + 2) (with H shift) and (4 + 2) cycloaddition products, which can in principle interconvert via α-ketol rearrangements. The origins of periselectivity of this ambimodal cycloaddition have been investigated computationally with molecular dynamics simulations and tested further by an experimental study. In the presence of bicarbonate ions, the deprotonated hydroxy-o-quinone leads to only the (5 + 2) cycloaddition adduct. A new mechanism for a benzilic acid rearrangement resulting in ring contraction is proposed.

We tested in six fish species [Pacific lamprey (Lampetra richardsoni), Pacific spiny dogfish (Squalus suckleyi), Asian swamp eel (Monopterus albus), white sturgeon (Acipenser transmontanus), zebrafish (Danio rerio), and starry flounder (Platichthys stellatus)] the hypothesis that elevated extracellular [HCO3-] protects spontaneous heart rate and cardiac force development from the known impairments that severe hypoxia and hypercapnic acidosis can induce. Hearts were exposed in vitro to either severe hypoxia (~ 3% of air saturation), or severe hypercapnic acidosis (either 7.5% CO2 or 15% CO2), which reduced heart rate (in six test species) and net force development (in three test species). During hypoxia, heart rate was restored by [HCO3-] in a dose-dependent fashion in lamprey, dogfish and eel (EC50 = 5, 25 and 30 mM, respectively), but not in sturgeon, zebrafish or flounder. During hypercapnia, elevated [HCO3-] completely restored heart rate in dogfish, eel and sturgeon (EC50 = 5, 25 and 30 mM, respectively), had a partial effect in lamprey and zebrafish, and had no effect in flounder. Elevated [HCO3-], however, had no significant effect on net force of electrically paced ventricular strips from dogfish, eel and flounder during hypoxia and hypercapnia. Only in lamprey hearts did a specific soluble adenylyl cyclase (sAC) inhibitor, KH7, block the HCO3--mediated rescue of heart rate during both hypoxia and hypercapnia, and was the only species where we conclusively demonstrated sAC activity was involved in the protective effects of HCO3- on cardiac function. Our results suggest a common HCO3--dependent, sAC-dependent transduction pathway for heart rate recovery exists in cyclostomes and a HCO3--dependent, sAC-independent pathway exists in other fish species.

BackgroundSerum bicarbonate or total carbon dioxide (CO2) concentrations decline as chronic kidney disease (CKD) progresses and rise after dialysis initiation. While metabolic acidosis accelerates the progression of CKD and is associated with higher mortality among patients with end stage renal disease (ESRD), there are scarce data on the association of CO2 concentrations before ESRD transition with post-ESRD mortality.MethodsA historical cohort from the Transition of Care in CKD (TC-CKD) study includes 85,505 veterans who transitioned to ESRD from October 1, 2007, through March 31, 2014. After 1,958 patients without follow-up data, 3 patients with missing date of birth, and 50,889 patients without CO2 6 months prior to ESRD transition were excluded, the study population includes 32,655 patients. Associations between CO2 concentrations averaged over the last 6 months and its rate of decline during the 12 months prior to ESRD transition and post-ESRD all-cause, cardiovascular (CV), and non-CV mortality were examined by using hierarchical adjustment with Cox regression models.ResultsThe cohort was on average 68 ± 11 years old and included 29% Black veterans. Baseline concentrations of CO2 were 23 ± 4 mEq/L, and median (interquartile range) change in CO2 were -1.8 [-3.4, -0.2] mEq/L/year. High (≥28 mEq/L) and low (4 mEq/L/year.ConclusionBoth high and low pre-ESRD CO2 levels (≥28 and 4 mEq/L/year during 1 year before dialysis initiation were associated with greater post-ESRD all-cause, CV, and non-CV mortality. Further studies are needed to determine the optimal management of CO2 in patients with advanced CKD stages transitioning to ESRD.

Background: Forced vital capacity (FVC) remains difficult to determine for some patients suffering from amyotrophic lateral sclerosis (ALS) due to the rapid progression of the disease. Arterial blood gas (ABG) parameters could represent a valuable alternative. The aim of this study was therefore to evaluate the correlation between ABG parameters and FVC, along with the prognostic ability of ABG parameters, in a large cohort of ALS patients. Methods: ALS patients (n=302) with FVC and ABG parameters available at diagnosis were included. Correlations between ABG parameters and FVC were evaluated. Cox regression was then carried out to determine the association of each parameter (ABG and clinical data) with survival. Finally, receiver operating characteristic (ROC) curves were built to predict the survival of ALS. Results: Bicarbonates (HCO3−), oxygen partial pressure (pO2), carbon dioxide partial pressure (pCO2), base excess (BE), oxygen saturation and oxyhemoglobin were significantly correlated with FVC both in patients with spinal or bulbar onset. Univariate Cox regression showed that HCO3− and BE were associated with survival but only in spinal forms. ABG parameters predicted the survival of ALS with a similar performance to FVC, HCO3− being the parameter with the highest area under the curve. Conclusions: Our results suggest that there is an interest in conducting a longitudinal evaluation throughout disease progression to confirm the equal performances of FVC and ABG. This study highlights the benefits of performing ABG analysis that could be used as an interesting alternative to FVC when spirometry cannot be performed. [ABSTRACT FROM AUTHOR]

The aim was to evaluate the stability of serum bicarbonate at room temperature, depending on time to centrifugation and air exposure. Stability study was conducted in the laboratory of Clinical Hospital Centre Rijeka, Croatia in January-February 2022. Nine samples from 10 volunteers were collected in clot activator gel tubes (Greiner Bio-One). Bicarbonate was measured on Beckman Coulter AU480 (Beckman Coulter, Brea, USA). Three tubes were left at room temperature for 30 min, three tubes for 2 h, three tubes for 4 h until centrifugation. First tube from first group (baseline) was measured immediately after centrifugation. Other measurements were expressed as percentage deviation (PD%) from baseline. First tube was remeasured after 1 and 2 h (OT_0h_1h; OT_0h_2h). Second and third tubes were opened 1 and 2 h after centrifugation (C_0h_1h; C_0h_2h). Second group of tubes was processed the same way with 2-hour centrifugation delay (WB_2h; OT_2h_1h; OT_2h_2h; C_2h_1h; C_2h_2h), and third group with 4-hour delay (WB_4h; OT_4h_1h; OT_4h_2h; C_4h_1h; C_4h_2h). PD% was compared to Maximum Permissible Difference (MPD=5.69%). MedCalc statistical software was used (MedCalc, Ostend, Belgium). Bicarbonate baseline mean value (range) was 27.3 (23.4–29.6) mmol/L. Obtained PD% (95%CI) were: C_0h_1h 0.46 (−1.21, 2.12); C_0h_2h 0.18 (−2.22, 2.57); OT_0h_1h −6.46 (−7.57, −5.36); OT_0h_2h −10.67 (−12.13, −9.21); WB_2h −0.15 (−2.04, 1.74); C_2h_1h 0.01 (−1.52, 1.54); C_2h_2h −0.40 (−2.65, 1.85); OT_2h_1h −5.43 (−7.30, −3.55); OT_2h_2h −11.32 (−13.57, −9.07); WB_4h −0.85 (−3.28, 1.58); C_4h_1h −2.52 (−4.93, 0.11); C_4h_2h −3.02 (−5.62, 0.43); OT_4h_1h −7.34 (−9.64, −5.05); OT_4h_2h −11.85 (−14.38, −9.33). Serum bicarbonate is stable for 4 h in closed uncentrifuged tubes, another 2 h in closed tubes after centrifugation, and is unstable within 1 h in opened tube. [ABSTRACT FROM AUTHOR]

Background/objectivesDiet can affect the acid-base status depending on the balance between the intake of acid-inducing foods and base-inducing foods. The purpose of this study was to estimate the dietary acid load and evaluate its association with serum bicarbonate in patients with stages 3 and 4 chronic kidney disease.Subjects/methodsOne hundred adults (aged ≥ 20 years) with chronic kidney disease (CKD) stages 3 and 4 were enrolled in a cross-sectional study. A food diary was used to estimate the animal and plant protein intakes, which were used in the potential renal acid load (PRAL) formula described by Remer and Manz. PRAL was divided into quartiles. Regression models unadjusted and adjusted for age, gender, body mass index, diabetes, systolic and diastolic blood pressure, creatinine clearance were performed using the stepwise regression method.ResultsThe median level (25th, 75th percentiles) of PRAL was 8.3 mEq/day (1.6, 15.6). The highest quartile of PRAL had a higher consumption of animal protein (77.8 ± 10.9%) and a reduced consumption of plant protein (22.2 ± 10.9%), compared to the lowest quartile (59.5 ± 18.6% animal protein, 40.5 ± 18.6% plant protein), p for trend

Supplementation of standard growth media (cation-adjusted Mueller-Hinton Broth [CAMHB]) with bicarbonate (NaHCO3) increases β-lactam susceptibility of selected methicillin-resistant Staphylococcus aureus (MRSA) strains ("NaHCO3 responsive"). This "sensitization" phenomenon translated to enhanced β-lactam efficacy in a rabbit model of endocarditis. The present study evaluated NaHCO3-mediated β-lactam MRSA sensitization using an ex vivo pharmacodynamic model, featuring simulated endocardial vegetations (SEVs), to more closely mimic the host microenvironment. Four previously described MRSA strains were used: two each exhibiting in vitro NaHCO3-responsive or NaHCO3-nonresponsive phenotypes. Cefazolin (CFZ) and oxacillin (OXA) were evaluated in CAMHB with or without NaHCO3 Intra-SEV MRSA killing was determined over 72-h exposures. In both "responsive" strains, supplementation with 25 mM or 44 mM NaHCO3 significantly reduced β-lactam MICs to below the OXA susceptibility breakpoint (≤4 mg/liter) and resulted in bactericidal activity (≥3-log killing) in the model for both OXA and CFZ. In contrast, neither in vitro-defined nonresponsive MRSA strain showed significant sensitization in the SEV model to either β-lactam. At both NaHCO3 concentrations, the fractional time above MIC was >50% for both CFZ and OXA in the responsive MRSA strains. Also, in media containing RPMI plus 10% Luria-Bertani broth (proposed as a more host-mimicking microenvironment and containing 25 mM NaHCO3), both CFZ and OXA exhibited enhanced bactericidal activity against NaHCO3-responsive strains in the SEV model. Neither CFZ nor OXA exposures selected for emergence of high-level β-lactam-resistant mutants within SEVs. Thus, in this ex vivo model of endocarditis, in the presence of NaHCO3 supplementation, both CFZ and OXA are highly active against MRSA strains that demonstrate similar enhanced susceptibility in NaHCO3-supplemented media in vitro.

Introduction Abnormalities in blood bicarbonates (HCO3–) concentration are a common finding in patients with chronic kidney disease, especially at the end-stage renal failure. Initiating of hemodialysis does not completely solve this problem. The recommendations only formulate the target concentration of ≥22 mmol/L before hemodialysis but do not guide how to achieve it. The aim of the study was to assess the acid–base balance in everyday practice, the effect of hemodialysis session and possible correlations with clinical and biochemical parameters in stable hemodialysis patients.Material and methods We enrolled 75 stable hemodialysis patients (mean age 65.5 years, 34 women), from a single Department of Nephrology. We assessed blood pressure, and acid–base balance parameters before and after mid-week hemodialysis session.Results We found significant differences in pH, HCO3– pCO2, lactate before and after HD session in whole group (p

The municipality of Puka in Albania has rich underground aquifers and results in many sites with natural water resources meeting water needs. According to data available from the General Directorate of Water Supply and Sewerage in 2015, out of 5,724 urban residents Puka Municipality, only 2747 were connected to the water supply network (1,105 connections), while in rural areas, out of about 12,000 inhabitants, only 2,350 were connected to the network (523 connections), the rest of the population use artisanal wells and drilling. The main purpose of this paper was to evaluate the quality of wells and drilling waters based on physico-chemical and microbiological parameters. In terms of physico-chemical results, pH, ammonia, nitrate, nitrite, organic matter, calcium, magnesium, total hardness, chlorides, bicarbonates and silicon have resulted in low levels, within the norms allowed by national and international standards. Water samples from drilling and wells were collected according to European recommendations and WHO legislation. The level of bacterial contamination was higher in summer months compared to other months. Drinking water results higher polluted in the second period of sampling July-August 2019. Bacteriological results show that during the period April-May, there was a lower bacterial loading on the wells in the drinking water from wells and drilling waters with Escherichia coli and Streptococcus faecalis. [ABSTRACT FROM AUTHOR]

PurposeRapid chemical exchange can affect SNR and pH measurement accuracy for hyperpolarized pH imaging with [13 C]bicarbonate. The purpose of this work was to investigate chemical exchange effects on hyperpolarized imaging sequences to identify optimal sequence parameters for high SNR and pH accuracy.MethodsSimulations were performed under varying rates of bicarbonate-CO2 chemical exchange to analyze exchange effects on pH quantification accuracy and SNR under different sampling schemes. Four pulse sequences, including 1 new technique, a multiple-excitation 2D EPI (multi-EPI) sequence, were compared in phantoms using hyperpolarized [13 C]bicarbonate, varying parameters such as tip angles, repetition time, order of metabolite excitation, and refocusing pulse design. In vivo hyperpolarized bicarbonate-CO2 exchange measurements were made in transgenic murine prostate tumors to select in vivo imaging parameters.ResultsModeling of bicarbonate-CO2 exchange identified a multiple-excitation scheme for increasing CO2 SNR by up to a factor of 2.7. When implemented in phantom imaging experiments, these sampling schemes were confirmed to yield high pH accuracy and SNR gains. Based on measured bicarbonate-CO2 exchange in vivo, a 47% CO2 SNR gain is predicted.ConclusionThe novel multi-EPI pulse sequence can boost CO2 imaging signal in hyperpolarized 13 C bicarbonate imaging while introducing minimal pH bias, helping to surmount a major hurdle in hyperpolarized pH imaging.

Endovascular infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major health care concern, especially infective endocarditis (IE). Standard antimicrobial susceptibility testing (AST) defines most MRSA strains as "resistant" to β-lactams, often leading to the use of costly and/or toxic treatment regimens. In this investigation, five prototype MRSA strains, representing the range of genotypes in current clinical circulation, were studied. We identified two distinct MRSA phenotypes upon AST using standard media, with or without sodium bicarbonate (NaHCO3) supplementation: one highly susceptible to the antistaphylococcal β-lactams oxacillin and cefazolin (NaHCO3 responsive) and one resistant to such agents (NaHCO3 nonresponsive). These phenotypes accurately predicted clearance profiles of MRSA from target tissues in experimental MRSA IE treated with each β-lactam. Mechanistically, NaHCO3 reduced the expression of two key genes involved in the MRSA phenotype, mecA and sarA, leading to decreased production of penicillin-binding protein 2a (that mediates methicillin resistance), in NaHCO3-responsive (but not in NaHCO3-nonresponsive) strains. Moreover, both cefazolin and oxacillin synergistically killed NaHCO3-responsive strains in the presence of the host defense antimicrobial peptide (LL-37) in NaHCO3-supplemented media. These findings suggest that AST of MRSA strains in NaHCO3-containing media may potentially identify infections caused by NaHCO3-responsive strains that are appropriate for β-lactam therapy.

Although small airways account for the largest fraction of the total conducting airway surfaces, the epithelial fluid and electrolyte transport in small, native airway epithelia has not been well characterized. Investigations have been limited, no doubt, by the complex tissue architecture as well as by its inaccessibility, small dimensions, and lack of applicable assays, especially in human tissues. To better understand how the critically thin layer of airway surface liquid (ASL) is maintained, we applied a "capillary"-Ussing chamber (area ≈1 mm2) to measure ion transport properties of bronchioles with diameters of ~2 mm isolated from resected specimens of excised human lungs. We found that the small human airway, constitutively and concurrently, secretes and absorbs fluid as observed in porcine small airways (50). We found that the human bronchiolar epithelium is also highly anion selective and constitutively secretes bicarbonate ( HCO3- ), which can be enhanced pharmacologically by cAMP as well as Ca2+-mediated agonists. Concurrent secretion and absorption of surface liquid along with HCO3- secretion help explain how the delicate volume of the fluid lining the human small airway is physiologically buffered and maintained in a steady state that avoids desiccating or flooding the small airway with ASL.

PurposeTo develop and translate a metabolite-specific imaging sequence using a symmetric echo planar readout for clinical hyperpolarized (HP) Carbon-13 (13 C) applications.MethodsInitial data were acquired from patients with prostate cancer (N = 3) and high-grade brain tumors (N = 3) on a 3T scanner. Samples of [1-13 C]pyruvate were polarized for at least 2 h using a 5T SPINlab system operating at 0.8 K. Following injection of the HP substrate, pyruvate, lactate, and bicarbonate (for brain studies) were sequentially excited with a singleband spectral-spatial RF pulse and signal was rapidly encoded with a single-shot echo planar readout on a slice-by-slice basis. Data were acquired dynamically with a temporal resolution of 2 s for prostate studies and 3 s for brain studies.ResultsHigh pyruvate signal was seen throughout the prostate and brain, with conversion to lactate being shown across studies, whereas bicarbonate production was also detected in the brain. No Nyquist ghost artifacts or obvious geometric distortion from the echo planar readout were observed. The average error in center frequency was 1.2 ± 17.0 and 4.5 ± 1.4 Hz for prostate and brain studies, respectively, below the threshold for spatial shift because of bulk off-resonance.ConclusionThis study demonstrated the feasibility of symmetric EPI to acquire HP 13 C metabolite maps in a clinical setting. As an advance over prior single-slice dynamic or single time point volumetric spectroscopic imaging approaches, this metabolite-specific EPI acquisition provided robust whole-organ coverage for brain and prostate studies while retaining high SNR, spatial resolution, and dynamic temporal resolution.

In the United States, end-stage renal disease patients receiving hemodialysis have an exceedingly high risk of sudden cardiac death (SCD), accounting for 29% of death events, likely relating to their uremic milieu, recurring exposure to fluid and electrolyte fluxes, and underlying cardiovascular pathology. Furthermore, epidemiologic studies have shown that SCD events, as well as mortality and hospitalizations, occur most frequently on the first dialysis day after the long interdialytic gap, suggesting that abrupt fluctuations in the accumulation and removal of electrolytes, fluid, and uremic toxins over the dialysis cycle may be contributory. Some population-based observational studies have suggested that lower dialysate potassium concentrations appear to be associated with a heightened risk of postdialysis cardiac arrest in hemodialysis patients, although the optimal serum-to-dialysate potassium gradient remains unclear. Some observational studies have suggested that low dialysate calcium concentrations and high serum-to-dialysate calcium gradients may predispose patients to SCD. There is ongoing controversy about an association between higher dialysate bicarbonate concentrations and higher risk of cardiac arrest, likely owing to confounding by indication. Some observational studies also have shown that large interdialytic weight gains, fluid retention, and high ultrafiltration rates are linked with higher risk of SCD and mortality. However, there remains considerable controversy regarding the pros and cons of designating a specific upper ultrafiltration limit with extended treatment times as a clinical practice measure, and further studies are needed to define the optimal tools, metrics, targets, and implementation measures for volume control in the hemodialysis population. In this review, we highlight the epidemiology and pathophysiology of how specific aspects of the hemodialysis procedure may relate to the risk of SCD, as well as preventative strategies and future research directions that can address this risk.

In the United States, end-stage renal disease patients receiving hemodialysis have an exceedingly high risk of sudden cardiac death (SCD), accounting for 29% of death events, likely relating to their uremic milieu, recurring exposure to fluid and electrolyte fluxes, and underlying cardiovascular pathology. Furthermore, epidemiologic studies have shown that SCD events, as well as mortality and hospitalizations, occur most frequently on the first dialysis day after the long interdialytic gap, suggesting that abrupt fluctuations in the accumulation and removal of electrolytes, fluid, and uremic toxins over the dialysis cycle may be contributory. Some population-based observational studies have suggested that lower dialysate potassium concentrations appear to be associated with a heightened risk of postdialysis cardiac arrest in hemodialysis patients, although the optimal serum-to-dialysate potassium gradient remains unclear. Some observational studies have suggested that low dialysate calcium concentrations and high serum-to-dialysate calcium gradients may predispose patients to SCD. There is ongoing controversy about an association between higher dialysate bicarbonate concentrations and higher risk of cardiac arrest, likely owing to confounding by indication. Some observational studies also have shown that large interdialytic weight gains, fluid retention, and high ultrafiltration rates are linked with higher risk of SCD and mortality. However, there remains considerable controversy regarding the pros and cons of designating a specific upper ultrafiltration limit with extended treatment times as a clinical practice measure, and further studies are needed to define the optimal tools, metrics, targets, and implementation measures for volume control in the hemodialysis population. In this review, we highlight the epidemiology and pathophysiology of how specific aspects of the hemodialysis procedure may relate to the risk of SCD, as well as preventative strategies and future research directions that can address this risk.

Abnormalities in blood bicarbonates (HCO3–) concentration are a common finding in patients with chronic kidney disease, especially at the end-stage renal failure. Initiating of hemodialysis does not completely solve this problem. The recommendations only formulate the target concentration of ≥22 mmol/L before hemodialysis but do not guide how to achieve it. The aim of the study was to assess the acid–base balance in everyday practice, the effect of hemodialysis session and possible correlations with clinical and biochemical parameters in stable hemodialysis patients. We enrolled 75 stable hemodialysis patients (mean age 65.5 years, 34 women), from a single Department of Nephrology. We assessed blood pressure, and acid–base balance parameters before and after mid-week hemodialysis session. We found significant differences in pH, HCO3– pCO2, lactate before and after HD session in whole group (p < 0.001; p < 0.001; p < 0.001; p = 0.001, respectively). Buffer bicarbonate concentration had only statistically significant effect on the bicarbonate concentration after dialysis (p < 0.001). Both pre-HD acid–base parameters and post-HD pH were independent from buffer bicarbonate content. We observed significant inverse correlations between change in the serum bicarbonates and only two parameters: pH and HCO3– before hemodialysis (p = 0.013; p < 0.001, respectively). Despite the improvement in hemodialysis techniques, acid–base balance still remains a challenge. The individual selection of bicarbonate in bath, based on previous single tests, does not improve permanently the acid–base balance in the population of hemodialysis patients. New guidelines how to correct acid–base disorders in hemodialysis patients are needed to have less 'acidotic' patients before hemodialysis and less 'alkalotic' patients after the session. [ABSTRACT FROM AUTHOR]

Spirulina platensis is a cyanobacterium well known for its use as a feed and food supplement with recognized nutritional and cosmetic values. Spirulina was cultivated in media containing up to zero g L–1 sodium bicarbonate using sugar cane molasses (SCM) as a source of bicarbonate. The standard culture media used for Spirulina production is Zarrouk medium with a high content of bicarbonate, often supplied as NaHCO3. The present work proposes the use of SCM to supplement the Spirulina culture medium, with the intention that the CO2 derived from bacterial fermentation—from the high concentration of sugars that it contains—will produce a sufficient amount of bicarbonate. The results obtained show there is no significant effect on the protein, chlorophyll a, and phycocyanin when using molasses but significant effect growth biomass. Biomass cultivation was successful by molasses, recommended that this industrial byproduct can be used as cost-effective for Spirulina cultivation. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To compare anion gap estimated through measured and calculated bicarbonate modalities to be used interchangeably in critically ill metabolic acidosis patients. METHODS: This cross-sectional study was conducted at Rehman Medical Institute, Peshawar, Pakistan from September 2019 to March 2020. Out of 390 critically ill patients, 200 cases of metabolic acidosis were selected by non-probability consecutive sampling technique. Measured and calculated bicarbonate values were obtained through Cobas-c 501© (Roche) using enzymatic method and Cobas-b 221© (Roche) blood gas analyzer respectively. Statistical analysis was done by using SPSS-23. RESULTS: Normal anion gap metabolic acidosis (NAG-MA) and high anion gap metabolic acidosis (HAG-MA) based on calculated bicarbonate levels was observed in 57 (28.5%) and 143 (71.5%) cases as compared to 55 (27.5%) and 145 (72.5%) cases based on measured bicarbonate levels respectively (p>0.45). A significant correlation (r=0.888 and 0.656, r2=0.788 and 0.431) (p

Increases in CO2 concentration in plant leaves due to respiration in the dark and the continuing atmospheric [CO2] rise cause closing of stomatal pores, thus affecting plant-water relations globally. However, the underlying CO2/bicarbonate (CO2/HCO3-) sensing mechanisms remain unknown. [CO2] elevation in leaves triggers stomatal closure by anion efflux mediated via the SLAC1 anion channel localized in the plasma membrane of guard cells. Previous reconstitution analysis has suggested that intracellular bicarbonate ions might directly up-regulate SLAC1 channel activity. However, whether such a CO2/HCO3- regulation of SLAC1 is relevant for CO2 control of stomatal movements in planta remains unknown. Here, we computationally probe for candidate bicarbonate-interacting sites within the SLAC1 anion channel via long-timescale Gaussian accelerated molecular dynamics (GaMD) simulations. Mutations of two putative bicarbonate-interacting residues, R256 and R321, impaired the enhancement of the SLAC1 anion channel activity by CO2/HCO3- in Xenopus oocytes. Mutations of the neighboring charged amino acid K255 and residue R432 and the predicted gate residue F450 did not affect HCO3- regulation of SLAC1. Notably, gas-exchange experiments with slac1-transformed plants expressing mutated SLAC1 proteins revealed that the SLAC1 residue R256 is required for CO2 regulation of stomatal movements in planta, but not for abscisic acid (ABA)-induced stomatal closing. Patch clamp analyses of guard cells show that activation of S-type anion channels by CO2/HCO3-, but not by ABA, was impaired, indicating the relevance of R256 for CO2 signal transduction. Together, these analyses suggest that the SLAC1 anion channel is one of the physiologically relevant CO2/HCO3- sensors in guard cells.

Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.

BACKGROUND AND OBJECTIVES:Patients undergoing hemodialysis with a frequency other than thrice weekly are not included in current clinical performance metrics for dialysis adequacy. The weekly standard Kt/Vurea incorporates treatment frequency, but there are limited data on its association with clinical outcomes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:We used multivariable regression to examine the association of dialysis standard Kt/Vurea with BP and metabolic control (serum potassium, calcium, bicarbonate, and phosphorus) in patients incidental to dialysis treated with home (n=2373) or in-center hemodialysis (n=109,273). We further used Cox survival models to examine the association of dialysis standard Kt/Vurea with mortality, hospitalization, and among patients on home hemodialysis, transfer to in-center hemodialysis. RESULTS:After adjustment for potential confounders, patients with dialysis standard Kt/Vurea

Land degradation is a major threat to environmental sustainability (Mehrabi et al., 2021). About 25% of the earth's surface is alkaline in nature and nutrient deficiencies are common in such lands (López-Bucio et al. 2000). Aromatic grasses are the economically important grasses and essential oil produced by these grasses has tremendous demand worldwide. Present status of essential oil production by these grasses is less than the market demand. Although, these grasses are adapted to various ecological conditions but iron deficiency chlorosis is prominent under alkaline soils. Losses due to iron chlorosis in groundnut, maize and other field crops were studied in past and treatments consisting organic, inorganic salts, Fe-chelates, nanoparticles were suggested to minimize the losses. Fe-chelates such as Fe-eddha are effective but are not economical and much expensive. These grasses not being food crop utilized mainly for secondary metabolites production makes them a potential economical source to farmers’ practicing agriculture on marginal lands. Severe decline in crop yield, quality and physiological parameters due to IDC were studied in palmarosa, lemongrass and citronella; however, sufficient mitigation studies in aromatic grasses is not much explored. Understanding the causes, occurrence and mitigation experiments involving microbial consortia (s) or other resistant varieties for the IDC conditions becomes a necessity to find approaches to minimize the losses in commercially cultivated aromatic grasses.

Objective: In this study, we aimed to compare stage 4 chronic kidney disease patients who received sodium bicarbonate treatment in the form of 500 mg capsules and 1000 mg gastro-resistant tablets. Methods: All patients with stage 4 chronic kidney disease presenting to the nephrology clinic between August 2020 and November 2020 were evaluated retrospectively. The patients were divided into 2 groups: sodium bicarbonate group and gastro-resistant sodium bicarbonate group. Groups were compared in terms of serum bicarbonate and side effects during follow-up. Results: A total of 43 stage 4 chronic kidney disease patients were included in this study. The bicarbonate change in both groups was statistically significant after the first week (P < .001). In the gastro-resistant sodium bicarbonate group bicarbonate level was significantly higher than the sodium bicarbonate group in the first week (P < .001). Conclusions: Gastro-resistant sodium bicarbonate seems to normalize serum sodium bicarbonate earlier than sodium bicarbonate. [ABSTRACT FROM AUTHOR]

Insufficient level of analytical quality of chloride determination in blood serum and plasma using routine ISE methods has been demonstrated by the external quality assessment (EQA), by assessment of bicarbonate interference, and longterm follow-up of patient results in approx. One hundred thirty laboratories in several countries. The principal issues are considerable differences between test kits and instruments of various producers. The cause is insufficient selectivity and signal stability of many commonly used chloride electrodes, leading to low diagnostic effectivity of measurement results. This can be demonstrated by extremely high reference change values (RCV). Paradoxically, for many years there was a functional reference system of chloride measurement and metrological traceability of routine methods calibration. [ABSTRACT FROM AUTHOR]

This study demonstrates the substantial role of bicarbonate within a zero-valent iron (ZVI) system in hydrogen evolution, demonstrating that heightened concentration levels notably enhance hydrogen output. The acetic acid performance production of seven different inocula was examined when exposed to ZVI and CO 2 as the sole carbon source, separately. Along the seven inocula, river and constructed wetland sludges show the highest production rates at 300 mg/L day -1 and 269 mg/L day -1 , respectively. Acetobacterium levels significantly rose in CO 2 -enriched environments, particularly in river and wetland sludges. Moreover, bacteria attached to ZVI showed accelerated hydrogen consumption and acetic acid production compared to their freely suspended or ZVI-detached counterparts when hydrogen was primarily added externally. This study highlighted the positive effect of high concentrations of soluble CO₂, which acted both as a reactant with ZVI for hydrogen production and as a substrate for homoacetogens, leading to high acetic acid generation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Currently, urine output is the leading variable used to tailor fluid resuscitation in patients with large TBSA burns. However, this metric often lags with respect to resuscitation. Our group sought to identify derangements in variables that precede development of oliguria (<30 cc/hr) that we hypothesize will aid in more efficient resuscitation. We performed a retrospective analysis of 146 adult patients admitted within 4 h of a large TBSA (>20%) burn. We then divided them into two cohorts: those who developed oliguria within 6 h of admission and those who did not. Patients who experienced early oliguria had a higher incidence of invasive SBP < 90 (p = 0.02) or DBP < 40 (p = 0.009), lower minimum bicarbonate level (p = 0.04), more full thickness burns (p = 0.004), and higher TBSA (p = 0.01). More female patients were found in the oliguric group (p = 0.003). Multivariate analysis was used to develop a model to predict development of oliguria. When evaluated together, minimum DBP, sex, TBSA (or percent full thickness burn), and maximum base deficit constituted the most parsimonious model that significantly predicted oliguria (AUC = 0.92). Interestingly, the model lost significance when DBP was omitted, highlighting the importance of diastolic pressure in the development of oliguria., Competing Interests: Declaration of Competing Interest The original Burn Resuscitation Decision Support System was developed in collaboration between the U.S. Army Institute of Surgical Research and the University of Texas Medical Branch at Galveston, TX. Following initial development, this technology was licensed to Arcos, Inc. (Missouri City, TX) for commercialization and FDA clearance under the trade name Burn Navigator. An author currently holds a patent related to the device - "Burn Patient Resuscitation System". Patent Number: US8597273B2. The authors report no conflict of interest., (Copyright © 2024 International Society of Burns Injuries. All rights reserved.)

Water chemistry and the utilization of brewing salts such as gypsum, magnesium sulfate and bicarbonates, have been well documented for Saccharomyces cerevisiae, however, there has been limited published research on the impact bicarbonates have on Brettanomyces, especially in a brewing application. The objective of this project was to look at varying levels of added bicarbonates (0, 50, 75 and 100 mg/L) to identify correlations between bicarbonate content and the fermentation activity of Brettanomyces bruxellensis within beer. Two, 58.7 L brews with a target OG of 1.040 were brewed using a recirculating infusion mash system and mixed-together using a mash mixer to create one, 117.4 L batch to reduce variability. The batch was split into three, 37.9 L allotments and treated as triplicates. The beer was hopped to 20 IBUs using Bravo hops. Brettanomyces bruxellensis was propagated prior to being pitched at 1.2 million cells per degree Plato. After inoculation, the triplicates were stored at 21 °C until fermentation was completed. The reduction in gravity caused by the Brettanomyces was followed using a digital airlock and a benchtop densitometer. GC-MS was used for the analysis of the volatile compounds within the experimental beers. Statistical analysis (p < 0.05) showed that there were significant differences between the fermentation activity, including flavor compound production, of the different batches brewed at different bicarbonate levels. The total concentration of volatiles ranged from 69.76 to 83.4 mg/L within the different beers. It was concluded that the varying levels of bicarbonates had an impact not only on the fermentation, but also on the volatile compounds. [ABSTRACT FROM AUTHOR]