Sodium bicarbonate induces alkalosis, but improves high-intensity cycling performance only when participants expect a beneficial effect: a placebo and nocebo study

The study aimed to investigate the effects of sodium bicarbonate (NaHCO3) intake with divergent verbal and visual information on constant load cycling time-to-task failure, conducted within the severe intensity domain. Fifteen recreational cyclists participated in a randomized double-blind, crossover study, ingesting NaHCO3 or placebo (i.e., dextrose), but with divergent information about its likely influence (i.e., likely to induce ergogenic, inert, or harmful effects). Performance was evaluated using constant load cycling time to task failure trial at 115% of peak power output estimated during a ramp incremental exercise test. Data on blood lactate, blood acid-base balance, muscle electrical activity (EMG) through electromyography signal, and the twitch interpolation technique to assess neuromuscular indices were collected. Despite reduced peak force in the isometric maximal voluntary contraction and post-effort peripheral fatigue in all conditions (P < 0.001), neither time to task failure, EMG nor, blood acid-base balance differed between conditions (P > 0.05). Evaluation of effect sizes of all conditions suggested that informing participants that the supplement would be likely to have a positive effect (NaHCO3/Ergogenic: 0.46; 0.15-0.74; Dextrose/Ergogenic: 0.45; 0.04-0.88) resulted in improved performance compared to control. Thus, NaHCO3 ingestion consistently induced alkalosis, indicating that the physiological conditions to improve performance were present. Despite this, NaHCO3 ingestion did not influence performance or indicators of neuromuscular fatigue. In contrast, effect size estimates indicate that participants performed better when informed that they were ingesting an ergogenic supplement. These findings suggest that the apparently ergogenic effect of NaHCO3 may be due, at least in part, to a placebo effect.

Citrate anticoagulation in plasma exchange followed by continuous renal replacement therapy in critically ill children

OBJECTIVE

To investigate the effectiveness and safety of regional citrate-anticoagulated (RCA) plasma exchange (PE) and whether citrate-related metabolic disorders can be improved by sequential RCA continuous renal replacement therapy (CRRT).

METHODS

This retrospective, single-center observational study included 79 critically ill children requiring PE followed by CRRT (June 2018 to June 2021) at the Pediatric Intensive Care Unit of Hunan Children's Hospital, China. Patients were divided into the RCA-PE (n = 30) and systemic heparin anticoagulation (SHA-PE) (n = 49) groups. Filter level comparison post-PE assessed RCA-PE efficacy, and metabolic changes occurring pre- and post-PE and CRRT were used to evaluate the effect of CRRT on RCA-based anticoagulation safety.

RESULTS

The RCA-PE group had a better overall filter performance than the SHA-PE group. Two hours after PE, pH and HCO₃- levels increased more significantly for the RCA-PE than the SHA-PE group. The RCA-PE incidence of metabolic alkalosis was 48.3%, higher by 4.2% (p < 0.001) compared to the SHA-PE group. In the RCA-PE group, pH and HCO₃- decreased significantly 4 h after CRRT; the metabolic alkalosis caused by RCA-PE decreased to 13.8% (p = 0.005). No significant difference in pH, HCO₃-, and metabolic alkalosis incidence was observed between the two groups 4 h after CRRT.

CONCLUSIONS

The overall filtration performance of RCA-PE is superior to that of SHA-PE followed by CRRT. The metabolic complications associated with RCA-PE are mainly metabolic alkalosis that can be improved by using CRRT after RCA-PE and this is a better alternative for anticoagulation during PE in critically ill children.

A pilot study of fecal pH and redox as functional markers in the premature infant gut microbiome

The infant gut microbiome is a crucial factor in health and development. In preterm infants, altered gut microbiome composition and function have been linked to serious neonatal complications such as necrotizing enterocolitis and sepsis, which can lead to long-term disability. Although many studies have described links between microbiome composition and disease risk, there is a need for biomarkers to identify infants at risk of these complications in practice. In this pilot study, we obtained stool samples from preterm infant participants longitudinally during the first postnatal months, and measured pH and redox, as well as SCFA content and microbiome composition by 16S rRNA gene amplicon sequencing. These outcomes were compared to clinical data to better understand the role of pH and redox in infant gut microbiome development and overall health, and to assess the potential utility of pH and redox as biomarkers. We found that infants born earlier or exposed to antibiotics exhibited increased fecal pH, and that redox potential increased with postnatal age. These differences may be linked to changes in SCFA content, which was correlated with pH and increased with age. Microbiome composition was also related to birth weight, age, pH, and redox. Our findings suggest that pH and redox may serve as biomarkers of metabolic state in the preterm infant gut.

Clinical Research on Rett Syndrome: Central Hypoxemia and Hypokalemic Metabolic Alkalosis

Background

Rett syndrome (RTT) is now widely recognized as a profound neurological disorder that predominantly affects females and is closely associated with mutations in the methylated CpG binding protein 2 (MECP2) gene located on the X chromosome. The Characteristic symptoms of RTT include the loss of acquired language and motor skills, repetitive hand movements, irregular breathing, and seizures. Additionally, RTT patients may experience sporadic episodes of gastrointestinal problems, hypoplasia, early-onset osteoporosis, bruxism, and screaming episodes. It is worth noting that males exhibit a unique and variable phenotype, though rare in RTT cases, often accompanied by severe manifestations.

Case Presentation

In this report, we present the case of a young male child with a de novo c.806delG hemizygous mutation, leading to an atypical presentation of RTT that remarkably mirrors the clinical features of Bartter syndrome, a genetic metabolic disorder. The clinical manifestations in this case included the loss of previously acquired language and motor skills, repetitive hand movements, breathing irregularities, seizures, sporadic episodes of gastrointestinal distress, hypoplasia, early-onset osteoporosis, bruxism, and episodes of screaming. This distinctive presentation underscores the complex diagnostic landscape of RTT, particularly in males, and highlights the need for vigilant clinical evaluation.

Conclusions

This case report sheds light on an unusual and atypical presentation of RTT in a young male child with a de novo c.806delG hemizygous mutation. The resemblance of clinical features to Bartter syndrome underscores the diagnostic challenges posed by RTT and highlights the importance of comprehensive clinical assessment and genetic testing, especially in cases deviating from the typical RTT phenotype. Our findings contribute valuable insights into the early diagnosis and management of atypical RTT presentations.

Gitelman syndrome combined with diabetes mellitus: A case report and literature review

RATIONALE

Gitelman syndrome (GS) is an uncommon autosomal recessive tubulopathy resulting from a functional deletion mutation in the SLC12A3 gene. Its onset is typically insidious and challenging to discern, and it is characterized by hypokalemia, metabolic alkalosis, and reduced urinary calcium excretion. There is limited literature on the diagnosis and management of GS in individuals with concomitant diabetes.

PATIENT CONCERNS

A 36-year-old male patient with a longstanding history of diabetes exhibited suboptimal glycemic control. Additionally, he presented with concurrent findings of hypokalemia, hypomagnesemia, hypocalciuria, and metabolic alkalosis.

DIAGNOSIS

Building upon the patient's clinical manifestations and extensive laboratory evaluations, we conducted thorough genetic testing, leading to the identification of a compound heterozygous mutation within the SLC12A3 gene. This definitive finding confirmed the diagnosis of GS.

INTERVENTIONS

We have formulated a detailed medication regimen for patients, encompassing personalized selection of hypoglycemic medications and targeted electrolyte supplementation.

OUTCOMES

Following 1 week of comprehensive therapeutic intervention, the patient's serum potassium level effectively normalized to 3.79 mmol/L, blood glucose parameters stabilized, and there was significant alleviation of clinical symptoms.

LESSONS

GS has a hidden onset and requires early diagnosis and intervention based on patient related symptoms and laboratory indicators in clinical practice, and personalized medication plans need to be provided according to the specific situation of the patient.

Expanding Genotype-Phenotype Correlation of CLCNKA and CLCNKB Variants Linked to Hearing Loss

The ClC-K channels CLCNKA and CLCNKB are crucial for the transepithelial transport processes required for sufficient urinary concentrations and sensory mechanoelectrical transduction in the cochlea. Loss-of-function alleles in these channels are associated with various clinical phenotypes, ranging from hypokalemic alkalosis to sensorineural hearing loss (SNHL) accompanied by severe renal conditions, i.e., Bartter's syndrome. Using a stepwise genetic approach encompassing whole-genome sequencing (WGS), we identified one family with compound heterozygous variants in the ClC-K channels, specifically a truncating variant in CLCNKA in trans with a contiguous deletion of CLCNKA and CLCNKB. Breakpoint PCR and Sanger sequencing elucidated the breakpoint junctions derived from WGS, and allele-specific droplet digital PCR confirmed one copy loss of the CLCNKA_CLCNKB contiguous deletion. The proband that harbors the CLCNKA_CLCNKB variants is characterized by SNHL without hypokalemic alkalosis and renal anomalies, suggesting a distinct phenotype in the ClC-K channels in whom SNHL predominantly occurs. These results expanded genotypes and phenotypes associated with ClC-K channels, including the disease entities associated with non-syndromic hearing loss. Repeated identification of deletions across various extents of CLCNKA_CLCNKB suggests a mutational hotspot allele, highlighting the need for an in-depth analysis of the CLCNKA_CLCNKB intergenic region, especially in undiagnosed SNHL patients with a single hit in CLCNKA.

Sodium Bicarbonate Ingestion in a Fasted State Improves 16.1-km Cycling Time-Trial Performance

PURPOSE

The use of sodium bicarbonate (SB) as a preexercise ergogenic aid has been extensively studied in short-duration high-intensity exercise. Very few studies have considered the effects of SB ingestion before prolonged high-intensity exercise. The aim of the present study was to determine the effects of a 0.3 g·kg -1 body mass dose of SB ingested before the start of a 16.1-km cycling time trial in cyclists.

METHOD

Ten trained male cyclists (age, 31.1 ± 9 yr; height, 1.84 ± 0.05 m; body mass, 82.8 ± 8.5 kg; and V̇O 2peak , 60.4 ± 3.1 mL·kg -1 ·min -1 ) completed this study. Participants ingested 0.3 g·kg -1 in gelatine (SB-G) and enteric capsules (SB-E) 1 wk apart to determine individualized time-to-peak alkalosis for each ingestion form. Using a randomized crossover design, participants then performed simulated 16.1-km time trials after ingestion of SB-G, SB-E, or a placebo.

RESULTS

There were significant differences in performance between the SB and placebo ingestion strategies ( f = 5.50, P = 0.014, p η2 = 0.38). Performance time was significantly improved by SB ingestion (mean improvement: 34.4 ± 42.6 s ( P = 0.031) and 40.4 ± 45.5 s ( P = 0.020) for SB-G and SB-E, respectively) compared with the placebo. Gastrointestinal symptoms were lower after SB-E compared with SB-G (36.3 ± 4.5 vs 5.6 ± 3.1 AU, P < 0.001, g = 7.09).

CONCLUSIONS

This study demonstrates that increased buffering capacity after acute preexercise SB ingestion can improve endurance cycling time-trial performances. The use of SB could be considered for use in 16.1-km cycling time trials, but further work is required to establish these effects after a preexercise meal.

Acetazolamide for metabolic alkalosis complicating respiratory failure with chronic obstructive pulmonary disease or obesity hypoventilation syndrome: a systematic review

BACKGROUND

Metabolic alkalosis may lead to respiratory inhibition and increased need for ventilatory support or prolongation of weaning from ventilation for patients with chronic respiratory disease. Acetazolamide can reduce alkalaemia and may reduce respiratory depression.

METHODS

We searched Medline, EMBASE and CENTRAL from inception to March 2022 for randomised controlled trials comparing acetazolamide to placebo in patients with chronic obstructive pulmonary disease, obesity hypoventilation syndrome or obstructive sleep apnoea, hospitalised with acute respiratory deterioration complicated by metabolic alkalosis. The primary outcome was mortality and we pooled data using random-effects meta-analysis. Risk of bias was assessed using the Cochrane RoB 2 (Risk of Bias 2) tool, heterogeneity was assessed using the I2 value and χ2 test for heterogeneity. Certainty of evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) methodology.

RESULTS

Four studies with 504 patients were included. 99% of included patients had chronic obstructive pulmonary disease. No trials recruited patients with obstructive sleep apnoea. 50% of trials recruited patients requiring mechanical ventilation. Risk of bias was overall low to some risk. There was no statistically significant difference with acetazolamide in mortality (relative risk 0.98 (95% CI 0.28 to 3.46); p=0.95; 490 participants; three studies; GRADE low certainty) or duration of ventilatory support (mean difference -0.8 days (95% CI -7.2 to 5.6); p=0.36; 427 participants; two studies; GRADE: low certainty).

CONCLUSION

Acetazolamide may have little impact on respiratory failure with metabolic alkalosis in patients with chronic respiratory diseases. However, clinically significant benefits or harms are unable to be excluded, and larger trials are required.

PROSPERO REGISTRATION NUMBER

CRD42021278757.

Telecoupled urban demand from West African cities causes social-ecological land use transformation in Saharan oases

Little is known about the long-distance telecoupling effects of urban food demands on land use changes (LUCs) in remote oases of the Southern Sahara. Using the example of two typical oasis settlements on Mont Bagzam in the southern Aϊr Mountains of Niger which are linked to regional and global markets by an unpaved road since 2015, this study aimed at analyzing time trajectories of LUCs and related changing agricultural production patterns. LUCs were quantified for 1955 to 2022 using GIS-based mapping of agriculture and natural vegetation based on historical aerial photographs, CORONA and multi-spectral satellite images, and high resolution drone-based surveys. The results show a major increment in actively used agricultural land in the 850 ha watershed of the two oases from 11 ha in 1955 to 13 ha in 2003 and 68 ha in 2022 as well as the addition of 92 irrigation wells to 16 existing ones between 2003 and 2022. LUCs and evapotranspiration calculated from climatic data of a local weather station allowed to estimate changes of irrigation water needs in the selected watershed. While annual precipitation averages only 214 mm, local reference evapotranspiration may reach 1,476 mm year-1. Therefore, the additional annual irrigation water needs for the newly established fields between 2003 and 2022 cultivated to cash crops rose by 696 million l. To detect LUC effects on soil quality, soil samples of onion and garlic fields of different ages were collected employing a false-time-series approach. Results reveal increasing soil pH and salt concentrations and falling ground water tables, which reflects a negative water balance and ground water extraction above recharge levels. Our study provides evidence that the newly established telecoupled production systems on Mont Bagzam threaten the sustainability of existing local agricultural production and related livelihoods of agro-pastoralists.

Dietary anions control potassium excretion: it is more than a poorly absorbable anion effect

The urinary potassium (K+) excretion machinery is upregulated with increasing dietary K+, but the role of accompanying dietary anions remains inadequately characterized. Poorly absorbable anions, including [Formula: see text], are thought to increase K+ secretion through a transepithelial voltage effect. Here, we tested if they also influence the K+ secretion machinery. Wild-type mice, aldosterone synthase (AS) knockout (KO) mice, or pendrin KO mice were randomized to control, high-KCl, or high-KHCO3 diets. The K+ secretory capacity was assessed in balance experiments. Protein abundance, modification, and localization of K+-secretory transporters were evaluated by Western blot analysis and confocal microscopy. Feeding the high-KHCO3 diet increased urinary K+ excretion and the transtubular K+ gradient significantly more than the high-KCl diet, coincident with more pronounced upregulation of epithelial Na+ channels (ENaC) and renal outer medullary K+ (ROMK) channels and apical localization in the distal nephron. Experiments in AS KO mice revealed that the enhanced effects of [Formula: see text] were aldosterone independent. The high-KHCO3 diet also uniquely increased the large-conductance Ca2+-activated K+ (BK) channel β4-subunit, stabilizing BKα on the apical membrane, the Cl-/[Formula: see text] exchanger, pendrin, and the apical KCl cotransporter (KCC3a), all of which are expressed specifically in pendrin-positive intercalated cells. Experiments in pendrin KO mice revealed that pendrin was required to increase K+ excretion with the high-KHCO3 diet. In summary, [Formula: see text] stimulates K+ excretion beyond a poorly absorbable anion effect, upregulating ENaC and ROMK in principal cells and BK, pendrin, and KCC3a in pendrin-positive intercalated cells. The adaptive mechanism prevents hyperkalemia and alkalosis with the consumption of alkaline ash-rich diets but may drive K+ wasting and hypokalemia in alkalosis.NEW & NOTEWORTHY Dietary anions profoundly impact K+ homeostasis. Here, we found that a K+-rich diet, containing [Formula: see text] as the counteranion, enhances the electrogenic K+ excretory machinery, epithelial Na+ channels, and renal outer medullary K+ channels, much more than a high-KCl diet. It also uniquely induces KCC3a and pendrin, in B-intercalated cells, providing an electroneutral KHCO3 secretion pathway. These findings reveal new K+ balance mechanisms that drive adaption to alkaline and K+-rich foods, which should guide new treatment strategies for K+ disorders.

Microbial hydrogen consumption leads to a significant pH increase under high-saline-conditions: implications for hydrogen storage in salt caverns

Salt caverns have been successfully used for natural gas storage globally since the 1940s and are now under consideration for hydrogen (H2) storage, which is needed in large quantities to decarbonize the economy to finally reach a net zero by 2050. Salt caverns are not sterile and H2 is a ubiquitous electron donor for microorganisms. This could entail that the injected H2 will be microbially consumed, leading to a volumetric loss and potential production of toxic H2S. However, the extent and rates of this microbial H2 consumption under high-saline cavern conditions are not yet understood. To investigate microbial consumption rates, we cultured the halophilic sulphate-reducing bacteria Desulfohalobium retbaense and the halophilic methanogen Methanocalculus halotolerans under different H2 partial pressures. Both strains consumed H2, but consumption rates slowed down significantly over time. The activity loss correlated with a significant pH increase (up to pH 9) in the media due to intense proton- and bicarbonate consumption. In the case of sulphate reduction, this pH increase led to dissolution of all produced H2S in the liquid phase. We compared these observations to a brine retrieved from a salt cavern located in Northern Germany, which was then incubated with 100% H2 over several months. We again observed a H2 loss (up to 12%) with a concurrent increase in pH of up to 8.5 especially when additional nutrients were added to the brine. Our results clearly show that sulphate-reducing microbes present in salt caverns consume H2, which will be accompanied by a significant pH increase, resulting in reduced activity over time. This potentially self-limiting process of pH increase during sulphate-reduction will be advantageous for H2 storage in low-buffering environments like salt caverns.

A case report of Gitelman syndrome in children

RATIONALE

Giltelman syndrome (GS) is an autosomal recessive infectious disease, which is caused by the mutation of SLC12A3 gene encoding thiazide diuretic sensitive sodium chloride cotransporter located in the distal convoluted tubule of the kidney.

PATIENT CONCERNS

A 7-year-old and 3-month-old male patient has poor appetite, slow growth in height and body weight since the age of 3, body weight: 16 kg (-3 standard deviation), height: 110 cm (-3 standard deviation), normal exercise ability and intelligence. One year ago, he was diagnosed with hypokalemia. After potassium supplement treatment, the blood potassium returned to normal. The patient developed abdominal pain, vomiting, limb weakness, and tetany 1 day before admission.

DIAGNOSES

After admission examination, the patient was found to have hypokalemia (2.27-2.88 mmol/L), hypomagnesemia (0.47 mmol/L), hypophosphatemia (1.17 mmol/L), hypocalcemia (1.06 mmol/24 hours), and metabolic alkalosis (PH 7.60). The blood pressure is normal, and the concentration of aldosterone is 791.63 pg/mL. The adrenocorticotropic hormone and cortisol detected at 8 am are 4.95 pmol/L and 275.09 nmol/L, respectively. Twenty-four hours of urine potassium is 32.52 mmol. Gene sequencing results showed 2 pathogenic variants in the GS-related SLC12A3 gene, which are related to the phenotype of the subject.

INTERVENTIONS

After admission, the patients were given potassium and magnesium supplements, as well as oral spironolactone. The symptoms of limb weakness and tetany were significantly relieved. After discharge, the patients continued to maintain treatment to keep the blood potassium at more than 3.0 mmol/L, and the blood magnesium at more than 0.6 mmol/L.

OUTCOMES

Follow-up at 1 month after discharge, in the patient's self-description, he had no symptoms such as limb weakness and tetany, and his height was increased by 1 cm and the body weight increased by 1.5 kg.

LESSONS

For patients with hypokalemia, hypomagnesemia, and metabolic alkalosis, the possibility of GS should be given priority. After the diagnosed by gene sequencing of SLC12A3 gene, potassium and magnesium supplementation could significantly improve symptoms.

Pendrin regulation is prioritized by anion in high-potassium diets

The Cl-/[Formula: see text] exchanger pendrin in the kidney maintains acid-base balance and intravascular volume. Pendrin is upregulated in models associated with high circulating aldosterone concentration, such as dietary NaCl restriction or an aldosterone infusion. However, it has not been established if pendrin is similarly regulated by aldosterone with a high-K+ diet because the effects of accompanying anions have not been considered. Here, we explored how pendrin is modulated by different dietary potassium salts. Wild-type (WT) and aldosterone synthase (AS) knockout (KO) mice were randomized to control, high-KHCO3, or high-KCl diets. Dietary KCl and KHCO3 loading increased aldosterone in WT mice to the same extent but had opposite effects on pendrin abundance. KHCO3 loading increased pendrin protein and transcript abundance. Conversely, high-KCl diet feeding caused pendrin to decrease within 8 h of switching from the high-KHCO3 diet, coincident with an increase in plasma Cl- and a decrease in [Formula: see text]. In contrast, switching the high-KCl diet to the high-KHCO3 diet caused pendrin to increase in WT mice. Experiments in AS KO mice revealed that aldosterone is necessary to optimally upregulate pendrin protein in response to the high-KHCO3 diet but not to increase pendrin mRNA. We conclude that pendrin is differentially regulated by different dietary potassium salts and that its regulation is prioritized by the dietary anion, providing a mechanism to prevent metabolic alkalosis with high-K+ base diets and safeguard against hyperchloremic acidosis with consumption of high-KCl diets.NEW & NOTEWORTHY Regulation of the Cl-/[Formula: see text] exchanger pendrin has been suggested to explain the aldosterone paradox. A high-K+ diet has been proposed to downregulate a pendrin-mediated K+-sparing NaCl reabsorption pathway to maximize urinary K+ excretion. Here, we challenged the hypothesis, revealing that the accompanying anion, not K+, drives pendrin expression. Pendrin is downregulated with a high-KCl diet, preventing acidosis, and upregulated with an alkaline-rich high-K+ diet, preventing metabolic alkalosis. Pendrin regulation is prioritized for acid-base balance.

Diabetic Ketoalkalosis: A Common Yet Easily Overlooked Alkalemic Variant of Diabetic Ketoacidosis Associated with Mixed Acid-Base Disorders

BACKGROUND

Diabetic ketoacidosis (DKA) is commonly complicated by mixed acid-base disorders. Therefore, patients with DKA can present with pH > 7.3 or bicarbonate > 18 mmol/L, which falls outside the values defined by the current traditional DKA criteria (pH ≤ 7.3 or bicarbonate ≤ 18 mmol/L).

OBJECTIVE

We aimed to study the spectrum of acid-base clinical presentations of DKA and the prevalence of diabetic ketoalkalosis.

METHODS

This study included all adult patients at a single institution admitted in 2018-2020 with diabetes, positive beta-hydroxybutyric acid, and increased anion gap ≥ 16 mmol/L. Mixed acid-base disorders were analyzed to determine the spectrum of presentation of DKA.

RESULTS

There were 259 encounters identified under the inclusion criteria. Acid-base analysis was available in 227 cases. Traditional acidemic DKA (pH ≤ 7.3), DKA with mild acidemia (7.3 < pH ≤ 7.4), and diabetic ketoalkalosis (pH > 7.4) account for 48.9% (111/227), 27.8% (63/227), and 23.3% (53/227) of cases, respectively. Of the 53 cases with diabetic ketoalkalosis, increased anion gap metabolic acidosis was present in all, and concurrent metabolic alkalosis, respiratory alkalosis, and respiratory acidosis were present in 47.2% (25/53), 81.1% (43/53), and 11.3% (6/53) encounters, respectively. In addition, 34.0% (18/53) of those with diabetic ketoalkalosis were found to have severe ketoacidosis, defined by beta-hydroxybutyric acid ≥ 3 mmol/L.

CONCLUSIONS

DKA can present as traditional acidemic DKA, DKA with mild acidemia, and diabetic ketoalkalosis. Diabetic ketoalkalosis is a common yet easily overlooked alkalemic variant of DKA associated with mixed acid-base disorders, and a high proportion of these presentations have severe ketoacidosis and thus, require the same treatment as traditional DKA.

Acid-base and hematological regulation in chicken embryos during internal progressive hypercapnic hypoxia

Development of the capacity to mitigate potential disturbances to blood physiology in bird embryos is incompletely understood. We investigated regulation of acid-base and hematology in day 15 chicken embryos exposed to graded intrinsic hypercapnic hypoxia created by varying degrees of water submersion. Metabolic acidosis with additional respiratory or metabolic acidosis occurred at 2 h according to magnitude of submersion. Acid-base disturbance was partially compensated by metabolic alkalosis at 6 h, but compensatory metabolic alkalosis was absent at 24 h. Following submersion with only air cell exposed to air, both hypercapnic respiratory acidosis and metabolic acidosis occurred within 10 min. Subsequently, both forms of acidosis created lethal levels of [HCO₃^-] at ∼120 min. Blood hematology showed small but significant effects associated with induced acid-base disturbance. Increased Hct occurring during partial egg submersion lasting 24 h was attributed to an increase in MCV. By day 15 of development chicken embryos are able to partially compensate for and withstand all but severe induced internal hypoxic hypercapnia.

An Unusual Case of a Primary Hyperparathyroidism Mimic

A 32-year-old lady with a history of bulimia nervosa was noted to have a raised adjusted calcium of 2.94mmol/L associated with high parathyroid hormone (PTH) 17.2pmol/L. On review, she had an apparent hypercalcaemia for at least three years, and also had a chronic, severe alkalosis with a bicarbonate up to 81.9mEQ/L. Ionised calcium during that time had actually been low, down to 1.03mmol/L. This case highlights the effects of alkalosis on calcium, as more albumin is available for binding to ionised calcium. This results in a low ionised calcium, which triggers PTH release and overall leads to raised adjusted calcium levels. Clinicians may misdiagnose a similar patient with primary hyperparathyroidism and treatment would cause worsening of true hypocalcaemia.

Degradation of hydrogel beads for the detection of serum bicarbonate levels for the diagnosis of metabolic alkalosis at the point of care

In this work, we present a novel point-of-care hydrogel-based diagnostic device for the rapid detection of elevated bicarbonate levels in serum for the diagnosis of mild to severe cases of metabolic alkalosis. Our system consists of hydrogel beads composed of calcium alginate and the nonionic polymer dextran. This assay utilizes the reaction of sodium bicarbonate and citric acid to produce citrate, a metal chelator capable of competitively binding to calcium cations in the gel matrix to trigger hydrogel degradation. This results in successful detection of elevated bicarbonate concentrations in less than one hour. Specifically, critically high bicarbonate concentrations of 50, 45, and 40 mmol L^-1 in human serum were detected in as little as 10, 15, and 20 min, respectively. To demonstrate the assay's feasibility for use in resource-limited settings, we developed a simple electronic device that achieved similar results and could be used by untrained individuals with no lab equipment and minimal power. To our knowledge, this is the first demonstration of the use of nonionic polymers to synthesize and improve the morphology of calcium alginate hydrogel beads using a simple processing method that involves minimal labor and equipment. The simplified bead synthesis protocol combined with the user-friendly device allows for the rapid detection of metabolic alkalosis at the point of care.

Analysis of Electrolyte Abnormalities in Adolescents and Adults and Subsequent Diagnosis of an Eating Disorder

IMPORTANCE

Eating disorders lead to increased mortality and reduced quality of life. While the acute presentations of eating disorders frequently involve electrolyte abnormalities, it remains unknown whether electrolyte abnormalities may precede the future diagnosis of an eating disorder.

OBJECTIVE

To determine whether outpatient electrolyte abnormalities are associated with the future diagnosis of an eating disorder.

DESIGN, SETTING, AND PARTICIPANTS

This population-level case-control study used provincial administrative health data for residents of Ontario, Canada aged 13 years or older from 2008 to 2020. Individuals without an eating disorder (controls) were matched 4:1 to individuals diagnosed with an incident eating disorder (cases) based on age and sex. Both groups had outpatient electrolyte measurements between 3 years and 30 days prior to index. Index was defined as the date of an eating disorder diagnosis in any inpatient or outpatient clinical setting for cases. Controls were assigned a pseudo-index date according to the distribution of index dates in the case population. Individuals with any prior eating disorder diagnosis were excluded. The data analyzed was from January 1, 2008, through June 30, 2020.

EXPOSURES

Any electrolyte abnormality, defined as abnormal test results for a composite of hypokalemia, hyperkalemia, hyponatremia, hypernatremia, hypomagnesemia, hypophosphatemia, metabolic acidosis, or metabolic alkalosis.

OUTCOMES AND MEASURES

Eating disorder diagnosis including anorexia nervosa, bulimia nervosa, and eating disorder not otherwise specified.

RESULTS

A total 6970 eligible Ontario residents with an eating disorder (mean [SD] age, 28 (19) years; 6075 [87.2%] female, 895 [12.8%] male) were matched with 27 878 age- and sex-matched residents without an eating disorder diagnosis (mean [SD] age, 28 [19] years; 24 300 [87.2%] female, 3578 [12.8%] male). Overall, 18.4% of individuals with an eating disorder had a preceding electrolyte abnormality vs 7.5% of individuals without an eating disorder (adjusted odds ratio [aOR], 2.12; [95% CI, 1.86-2.41]). The median (IQR) time from the earliest electrolyte abnormality to eating disorder diagnosis was 386 (157-716) days. Specific electrolyte abnormalities associated with a higher risk of an eating disorder were: hypokalemia (aOR, 1.98; 95% CI, 1.70-2.32), hyperkalemia (aOR, 1.97; 95% CI, 1.48-2.62), hyponatremia (aOR, 5.26; 95% CI, 3.32-8.31), hypernatremia (aOR, 3.09; 95% CI, 1.01-9.51), hypophosphatemia (aOR, 2.83; 95% CI, 1.82-4.40), and metabolic alkalosis (aOR, 2.60; 95% CI, 1.63-4.15).

CONCLUSIONS AND RELEVANCE

In this case-control study, individuals with an eating disorder were associated with a preceding outpatient electrolyte abnormality compared with matched controls. Otherwise unexplained electrolyte abnormalities may serve to identify individuals who may benefit from screening for an underlying eating disorder.

Alkaline-sensitive two-pore domain potassium channels form functional heteromers in pancreatic β-cells

Two-pore domain K⁺ channels (K_2P channels), active as dimers, produce inhibitory currents regulated by a variety of stimuli. Among them, TWIK1-related alkalinization-activated K⁺ channel 1 (TALK1), TWIK1-related alkalinization-activated K⁺ channel 2 (TALK2), and TWIK1-related acid-sensitive K⁺ channel 2 (TASK2) form a subfamily of structurally related K_2P channels stimulated by extracellular alkalosis. The human genes encoding these proteins are clustered at chromosomal region 6p21 and coexpressed in multiple tissues, including the pancreas. The question whether these channels form functional heteromers remained open. By analyzing single-cell transcriptomic data, we show that these channels are coexpressed in insulin-secreting pancreatic β-cells. Using in situ proximity ligation assay and electrophysiology, we show that they form functional heterodimers both upon heterologous expression and under native conditions in human pancreatic β-cells. We demonstrate that heteromerization of TALK2 with TALK1 or with TASK2 endows TALK2 with sensitivity to extracellular alkalosis in the physiological range. We further show that the association of TASK2 with TALK1 and TALK2 increases their unitary conductance. These results provide a new example of heteromerization in the K_2P channel family expanding the range of the potential physiological and pathophysiological roles of TALK1/TALK2/TASK2 channels, not only in insulin-secreting cells but also in the many other tissues in which they are coexpressed.

Positive Effects of Pre-exercise Metabolic Alkalosis on Perceived Exertion and Post-exercise Squat Jump Performance in World-Class Cyclists

ABSTRACT

Thomas, C, Delfour-Peyrethon, R, Dorel, S, and Hanon, C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. J Strength Cond Res 36(9): 2602-2609, 2022-This study aimed to determine the effects of pre-exercise alkalosis in world-class cyclists on their general (rate of perceived exertion [RPE]) and local (category-ratio scale [CR10]) perceived rates of exertion and acid-base status during 2 types of training sessions. Eight world-class cyclists ingested either sodium bicarbonate (BIC) or a placebo (PLA) in a double-blind and randomized order before performing 4 × 1,000 m constant-power sprints (CP) or 3 × 500 m all-out sprints (AO), with 20 minutes of recovery time between each session. For AO, the performance was assessed through the cycling sprint velocity and a squat jump test during recovery. During both tests, RPE, CR10, and acid-base status were measured. Sodium bicarbonate ingestion was effective in inducing pre-exercise alkalosis, compared with a PLA ( p < 0.05). During CP, performance and RPE were the same for BIC and PLA ( p > 0.05) with no time effect. The CR10 increased for the last sprint in PLA ( p < 0.05) but was attenuated in BIC (BIC: 6 vs. PLA: 8.2; p < 0.05), whereas there was no difference in acid-base status. During AO, RPE and CR10 increased with time, with no BIC effect, whereas blood lactate concentration was different ( p < 0.05). Sodium bicarbonate supplementation had no effect on overall repeated sprints ( p > 0.05). However, world-class athletes responded to BIC with higher squat jump performance than the PLA condition after AO ( p < 0.05). Our results suggest a positive influence of pre-exercise alkalosis in world-class cyclists on local perception of efforts after constant load sprints and an attenuation of muscle power output decline postsprint, as evidenced by improved squat jump performance after all-out cycling effort.

Clinical Course of Patients with Bartter Syndrome

INTRODUCTION

Bartter syndrome (BS) is a salt losing tubulopathy due to impairment of the transport mechanisms at the thick ascending limb of the Henle's loop. The aim of this study was to report the clinical course of patients with BS.

METHODS

Patients with BS were followed from 1996 to 2020 and enrolled to a systematic protocol to confirm primary BS by evaluating the metabolic derangements, nephrolithiasis and nephrocalcinosis. Treatment was based on standard guidelines. Comparisons were made between data at baseline and at the last visit.

RESULTS

A total of 13 patients (7 males) with primary BS were analyzed. Two patients had a mutation of the KCNJ1 gene. Age at diagnosis was 3 ± 4.5 years and the follow-up period was 11.19 ± 6.76 years. Metabolic alkalosis was initially detected in 76.92% and remained stable at the last visit (P > .05). Hypokalemia was present in 61.5% of patients at diagnosis, but sustained in 38.46% at the last visit (P < .05). Urine calcium level was 13.3 ± 9.6 mg/ kg/d at the first visit, and significantly reduced to 3.7 ± 2.0 mg/ kg/d at the last visit (P < .05). Nephrocalcinosis was detected by first kidney ultrasonography in 53.8% of patients. Kidney function was preserved, with a glomerular filtration rate of 120.1 ± 28.7 mL/min/ 1.73m2 at last visit. Growth was completely recovered in 71.42% and partially improved in 14.28% of patients after treatment, respectively. All patients received indomethacin and potassium chloride salts.

CONCLUSIONS

Long-term follow-up of this cohort of BS showed favorable outcomes after treatment resulting in metabolic normalization and growth catch-up in most patients.  DOI: 10.52547/ijkd.6657.

Antenatal Bartter syndrome: a new compound heterozygous mutation in exon 2 of KCNJ1 gene

A 30+6/7-week infant was born by vaginal delivery to a 21-year-old primigravida with pregnancy complicated by polyhydramnios. The infant developed polyuria and significant weight loss in the first 2 weeks of life despite appropriate fluid management. He developed hyponatraemia, hypochloraemia, transient hyperkalaemia and prerenal azotaemia with metabolic acidosis. On further evaluation, he had elevated plasma renin and aldosterone levels. Bartter syndrome was considered in the differential diagnosis. Bartter syndrome gene panel revealed a rare compound heterozygous mutation in exon 2 of the KCNJ1 gene (Lys186Glu/Thr71Met), suggesting antenatal Bartter syndrome (type 2). The infant developed late-onset hypokalaemia and metabolic alkalosis by week 4 of life. He regained birth weight by week 3 of life but failed to thrive (10-20 g/kg/day) despite high caloric intake (140 kcal/kg/day). His electrolyte abnormalities gradually improved, and he was discharged home without the need for electrolyte supplements or medications.

Does varying the ingestion period of sodium citrate influence blood alkalosis and gastrointestinal symptoms?

OBJECTIVES

To compare blood alkalosis, gastrointestinal symptoms and indicators of strong ion difference after ingestion of 500 mg.kg-1 BM sodium citrate over four different periods.

METHODS

Sixteen healthy and active participants ingested 500 mg.kg-1 BM sodium citrate in gelatine capsules over a 15, 30, 45 or 60 min period using a randomized cross-over experimental design. Gastrointestinal symptoms questionnaires and venous blood samples were collected before ingestion, immediately post-ingestion, and every 30 min for 480 min post-ingestion. Blood samples were analysed for blood pH, [HCO3-], [Na+], [Cl-] and plasma [citrate]. Linear mixed models were used to estimate the effect of the ingestion protocols.

RESULTS

For all treatments, blood [HCO3-] was significantly elevated above baseline for the entire 480 min post-ingestion period, and peak occurred 180 min post-ingestion. Blood [HCO3-] and pH were significantly elevated above baseline and not significantly below the peak between 150-270 min post-ingestion. Furthermore, blood pH and [HCO3-] were significantly lower for the 60 min ingestion period when compared to the other treatments. Gastrointestinal symptoms were minor for all treatments; the mean total session symptoms ratings (all times summed together) were between 9.8 and 11.6 from a maximum possible rating of 720.

CONCLUSION

Based on the findings of this investigation, sodium citrate should be ingested over a period of less than 60 min (15, 30 or 45 min), and completed 150-270 min before exercise.

Diagnosis and management of Bartter syndrome: executive summary of the consensus and recommendations from the European Rare Kidney Disease Reference Network Working Group for Tubular Disorders

Bartter syndrome is a rare inherited salt-losing renal tubular disorder characterized by secondary hyperaldosteronism with hypokalemic and hypochloremic metabolic alkalosis and low to normal blood pressure. The primary pathogenic mechanism is defective salt reabsorption predominantly in the thick ascending limb of the loop of Henle. There is significant variability in the clinical expression of the disease, which is genetically heterogenous with 5 different genes described to date. Despite considerable phenotypic overlap, correlations of specific clinical characteristics with the underlying molecular defects have been demonstrated, generating gene-specific phenotypes. As with many other rare disease conditions, there is a paucity of clinical studies that could guide diagnosis and therapeutic interventions. In this expert consensus document, the authors have summarized the currently available knowledge and propose clinical indicators to assess and improve quality of care.

A mathematical model of the four cardinal acid-base disorders

Precise maintenance of acid-base homeostasis is fundamental for optimal functioning of physiological and cellular processes. The presence of an acid-base disturbance can affect clinical outcomes and is usually caused by an underlying disease. It is, therefore, important to assess the acid-base status of patients, and the extent to which various therapeutic treatments are effective in controlling these acid-base alterations. In this paper, we develop a dynamic model of the physiological regulation of an HCO₃^-/CO₂ buffering system, an abundant and powerful buffering system, using Henderson-Hasselbalch kinetics. We simulate the normal physiological state and four cardinal acidbase disorders: Metabolic acidosis and alkalosis and respiratory acidosis and alkalosis. We show that the model accurately predicts serum pH over a range of clinical conditions. In addition to qualitative validation, we compare the in silico results with clinical data on acid-base homeostasis and alterations, finding clear relationships between primary acid-base disturbances and the secondary adaptive compensatory responses. We also show that the predicted primary disturbances accurately resemble clinically observed compensatory responses. Furthermore, via sensitivity analysis, key parameters were identified which could be the most effective in regulating systemic pH in healthy individuals, and those with chronic kidney disease and distal and proximal renal tubular acidosis. The model presented here may provide pathophysiologic insights and can serve as a tool to assess the safety and efficacy of different therapeutic interventions to control or correct acid-base disorders.

Acid-base disturbances in dehydrated patients with cystic fibrosis : four case reports with review of literature

Most episodes of vomiting, reduced intake and diarrhoea in children can be evaluated and treated without additional tests. However, when the degree of clinical dehydration is not in line with the patient's medical history, other diagnoses should be suspected. In the presence of a hyponatraemic hypochloraemic metabolic alkalosis, cystic fibrosis (CF) should be included in the differential diagnosis, especially if there is failure to thrive even in the absence of respiratory symptoms. Furthermore, young patients diagnosed with CF have a higher risk for an acute electrolyte decompensation caused by increased salt and fluid losses. We present 4 paediatric cases to raise the awareness of electrolyte disturbances in CF patients.

Antenatal Bartter Syndrome: A Case Report

Bartter syndrome is an autosomal recessive disorder manifested by a defect in sodium-potassium-chloride transport in the thick ascending limb of Henle with different genetic origins and molecular pathophysiology. Bartter syndrome usually a common disease in children and in early infancy presented with persistent polyuria and associated with dehydration, electrolyte imbalance, and failure to thrive. Though prompt diagnosis and proper treatment of Bartter syndrome may improve the outcome, some children will progress to renal failure. We report a case of a 6 days-old male infant who was admitted in Neonatal Intensive Care Unit, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh on 26 April 2018 for prematurity and low birth weight. On subsequent follow up he developed electrolyte imbalance and failure to thrive. Laboratory studies revealed hyponatremia, hypochloremic metabolic alkalosis with severe hypokalemia. When excessive chloride losses appear to be renal in origin and the patient has normal blood pressure and high levels of serum renin and aldosterone were considered as Bartter syndrome. Molecular genetic studies are indicated to identify the primary genetic defect.

Gitelmans Syndrome- A Rare Cause of Recurrent Syncope

Gitelman's syndrome, or congenital hypokalemic hypomagnesemic hypocalciuria with metabolic alkalosis, is widely described as a benign or milder variant of Barter's syndrome. It presents with variable clinical symptoms including tetanic episodes, muscle cramps, muscle paralysis, tingling numbness, perioral tingling sensation, salt craving and nocturia. This milder salt wasting syndrome can rarely cause significant ventricular arrhythmias and even death. Here, we report a case of 59 year old male who presented with history of recurrent syncope. He was found to have recurrent polymorphic VT with persistent hypokalemia and hypomagnesia. After extensive metabolic investigation, he was diagnosed as a case of Gitelman's syndrome. We report this case because of this rare malignant presentation of a seemingly benign syndrome.

[Rapid Resolution of Symptomatic Hypercalcaemia]

Rapid Resolution of Symptomatic Hypercalcaemia Abstract. Milk-alkali syndrome consists of the triad of hypercalcaemia, metabolic alkalosis, and renal insufficiency associated with the ingestion of calcium and absorbable alkali. Older patients, those at risk for volume depletion and those on medications that reduce glomerular filtration rate are at increased risk for the development of this syndrome. Most affected patients are postmenopausal women with chronic kidney disease who take an excessive amount of calcium carbonate. The incidence of milk-alkali syndrome is increasing due to the common supplementation of calcium carbonate. Nowadays, it is the third most common cause of hypercalcaemia. As shown in this case, hypercalcaemia may occur even with small amounts of calcium carbonate in patients with the given risk factors.

Implementation of a model of bodily fluids regulation

The classic model of blood pressure regulation by Guyton et al. (Annu Rev Physiol 34:13–46, 1972a; Ann Biomed Eng 1:254–281, 1972b) set a new standard for quantitative exploration of physiological function and led to important new insights, some of which still remain the focus of debate, such as whether the kidney plays the primary role in the genesis of hypertension (Montani et al. in Exp Physiol 24:41–54, 2009a; Exp Physiol 94:382–388, 2009b; Osborn et al. in Exp Physiol 94:389–396, 2009a; Exp Physiol 94:388–389, 2009b). Key to the success of this model was the fact that the authors made the computer code (in FORTRAN) freely available and eventually provided a convivial user interface for exploration of model behavior on early microcomputers (Montani et al. in Int J Bio-med Comput 24:41–54, 1989). Ikeda et al. (Ann Biomed Eng 7:135–166, 1979) developed an offshoot of the Guyton model targeting especially the regulation of body fluids and acid–base balance; their model provides extended renal and respiratory functions and would be a good basis for further extensions. In the interest of providing a simple, useable version of Ikeda et al.’s model and to facilitate further such extensions, we present a practical implementation of the model of Ikeda et al. (Ann Biomed Eng 7:135–166, 1979), using the ODE solver Berkeley Madonna.

Gitelman's Syndrome Presenting with Hypocalcaemia - A Case Report

Gitelman's syndrome is an autosomal recessive renal tubular disorder characterized by severe hypomagnesaemia, hypokalaemia, metabolic alkalosis and hypocalcaemia. It is caused by defective NaCl transport in the Distal Convoluted Tubule and presents in adolescence or adulthood, with a distinctly more benign course than Bartter's Syndrome. The dominant clinical features are muscle weakness, fatigue, carpopedal spasm, cramps and tetany. We report the case of a 26 year old male who presented with flaccid quadriparesis and carpopedal spasms, hypokalaemia, hypomagnesaemia, hypocalcaemia and severe urinary magnesium wasting. He was treated with potassium and magnesium supplementation and regained full function of all limbs.

[Clinical characteristics of five elderly patients with severe hypokalemia induced by glycyrrhizin derivatives]

Although hypokalemia is a common clinical problem, symptoms generally do not become manifest unless the serum potassium (K) falls rapidly. We encountered five cases with symptomatic severe hypokalemia (K<2.0 mEq/L) hospitalized for the past 15 months at our hospital. We examined the clinical characteristics and treatment of these patients. All five patients were women, and their mean age was 77.8 (73-82)years. They suffered from hypertension. Mean K level at admission was 1.66 (1.4-1.9) mEq/L and HCO3(-) was 48.3 (33.6-56.1) mmol/L. Plasma aldosterone level was low and plasma rennin activity was suppressed. All patients developed progressive muscle weakness with elevated creatinine phosphokinase. Three of the patients had received Chinese medicine which contained licorice, one received glycyrrhizin and the other one had received both. We diagnosed these cases as pseudoaldosteronism induced by glycyrrhizin. With discontinuation of the drugs and intravenous as well as oral K supplementation, serum K were normalized and clinical symptoms improved within 12 days. For one patient who developed cardiac dysfunction, concentrated K solution (230 mEq/L) was infused into the central vein. These findings show that glycyrrhizin ingestion should be kept in mind as a cause of an extreme degree of an hypokalemia, especially in elderly patients.

TRPC4 expression determines sensitivity of the platelet-type capacitative Ca2+entry channel to intracellular alkalosis

The present study was designed to analyze the molecular basis of the intracellular pH-dependent capacitative Ca2+ entry (CCE) of human platelets and megakaryocytic cells, specifically to test the hypothesis that members of the classical transient receptor potential (TRPC) protein family are involved in the CCE pathway that is promoted by intracellular alkalosis. Human platelets as well as the tested megakaryocytic cell lines (CMK cells, MEG-01 cells) and HEK293 cells displayed thapsigargin-induced CCE and responded to monensin with comparable elevation in intracellular pH. Promotion of CCE by monensin-induced intracellular alkalosis, however, was profound in mature platelets, moderate in CMK cells and lacking in MEG-01 cells as well as in HEK293 cells. Analysis of the TRPC expression pattern by immunoblotting revealed that mature platelets and CMK cells express TRPC4 along with TRPC1 and TRPC3, while TRPC4 is lacking in MEG-01 cells. HEK293 cells displayed CCE characteristics as well as lack of TRPC4 expression similar to MEG-01 cells. Over-expression of TRPC4 in HEK293 cells was found to result in a gain of pH-sensitivity of CCE with clearly detectable promotion of CCE in response to monensin. These results suggest that platelet CCE channel complexes contain TRPC4 as a molecular component that determines sensitivity of CCE to intracellular alkalosis.