Elevated Bicarbonate Research Articles

A four-season exploration of surface water quality and trophic status in the highly dynamic waters of Karun-4 Dam Lake, SW Iran

This study explores seasonal fluctuations in water quality and phytoplankton communities within Karun-4 Dam Lake, the largest double-arch dam in the Middle East situated in Iran. Employing a systematic approach, 26 sampling stations were strategically selected to collect surface water samples at a depth of 50 cm during the midpoints of each season throughout 2019. Significant seasonal variations in water quality parameters and phytoplankton composition were observed. Predominant species included Chrysophyceae (38%) and Bacillariophyceae (32%), indicative of nutrient-rich conditions, particularly during spring and summer, as evidenced by the eutrophic state (Carlson Trophic State Index: 59.43 and 53.96, respectively). Summer exhibited the highest diversity (Shannon–Wiener Index = 2.27) and lowest evenness (Pielou’s Evenness Index = 0.21). PCA and CCA analyses revealed season-specific preferences for nutrients and ions among phytoplankton species. Water temperature emerged as a crucial factor in spring and summer, while environments with elevated bicarbonate and alkalinity levels were less favorable during winter and fall. This study provides essential insights into Karun-4 Lake's dynamic ecological conditions, underscoring the necessity for ongoing monitoring to discern long-term trends and anthropogenic impacts for effective ecosystem management.

Loss of AC10 Impairs Neutrophil Recruitment and Alters Bacterial Colonization in the Lung During Bacterial Pneumonia

Rationale: Pseudomonas aeruginosa is a gram-negative bacterium and a common cause of nosocomial pneumonia that can progress to acute respiratory distress syndrome (ARDS), characterized by hypoxia, pulmonary edema, elevated bicarbonate, and widespread inflammation. Neutrophil recruitment is a critical line of defense against P. aeruginosa; however, excessive, or dysregulated neutrophil infiltration can exacerbate tissue damage and contribute to the severity of ARDS. Recently, AC10 has been implicated in neutrophil transendothelial migration via CD99. Despite the growing recognition and significance of AC10 in various physiological processes, its role in neutrophil recruitment during ARDS remains poorly understood. Thus, herein we hypothesize that loss of AC10 attenuates neutrophil recruitment during pneumonia and increase bacterial colonization in the lung. Methods: Wild-type and AC10 knockout mice were intratracheally inoculated with increasing doses of P. aeruginosa. Twenty fours after infection, bronchoalveolar lavage fluid (BALF) was collected and the percent of PMNs in the BALF determined. In separate experiments, mice were intratracheally inoculated with P. aeruginosa for 6 or 24 hours and organs (lungs, kidney, liver, spleen and brain) harvested, homogenized and the homogenate cultured overnight on Pseudomonas isolation agar for quantification of colony forming units (CFUs). Results: Our data confirmed CD99 expression in rat pulmonary microvascular endothelial cells and whole lung of both wild type and AC10 knockout mice. While there was no difference in the percentage of PMNs in the BALF between male wild type and knockout animals at any of the bacterial doses tested, in the female AC10 knockout mice, there was a decrease in the percentage of cells PMNs in the BALF compared to female wild type litter mates at several doses tested (1x103 up to 1x105, p<0.05). At a higher dose of P. aeruginosa (2.5x106), there was no difference in bacterial clearance between male WT and AC10 knockout mice, but a trend toward an increase in the CFU harvested from lung tissue 6 hours post infection in female KO mice. Conclusion: Thus, CD99 is expressed in the pulmonary endothelium. Further, in female mice, AC10 plays a role in neutrophil recruitment into the airspace. Further studies are required to resolve whether AC10 plays a role in bacterial clearance in female mice in a model of P. aeruginosa pneumonia. HL121513. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Iron transformation and hydroxyl radical production during mixing surface water and groundwater in the riparian zone: Effects of bicarbonate and surface water-groundwater ratio

The interaction between surface water and groundwater in the riparian zone significantly influences iron (Fe) transformation. This study characterized the Fe mineral composition of sediments collected from the riparian zones upstream and downstream of the Xinglong Dam of Han River, China. The coexistence of divalent (Fe–CO3) and Fe(III) minerals in the sediments suggested varying redox conditions of the riparian zone. Furthermore, the transformation processes of dissolved Fe(II) under different bicarbonate concentrations and surface water-groundwater ratios during the interaction between surface water and groundwater were investigated by laboratory batch experiments to understand the formation of Fe–CO3 and Fe(III) minerals in the riparian zone. The results demonstrated that elevated bicarbonate concentrations (0–20 mM) and surface water ratios promoted the transformation rate and amount of dissolved Fe(II) to solids. The predominant minerals of the formed solid were lepidocrocite, goethite, and Fe–CO3, according to the results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The rising bicarbonate concentration facilitated Fe–CO3 synthesis. The Fe(III) mineral (goethite) was more likely to develop when dissolved oxygen (DO) and bicarbonate concentrations were high. The generated hydroxyl radical (•OH) during dissolved Fe(II) oxidation was also increased with elevated HCO3− concentration and surface water ratio, indicating higher oxidative potential in the riparian zone with higher bicarbonate and surface water ratio. These findings offer insights into the Fe transformation in redox-fluctuating zones.

Acetazolamide and Hydrochlorothiazide in Patients With Acute Decompensated Heart Failure: Insights From Recent Trials.

Acetazolamide and thiazide diuretics have been combined with loop diuretics to overcome diuretic resistance in heart failure patients. However, recent studies have assessed the upfront combination of acetazolamide and hydrochlorothiazide with loop diuretics in hospitalized patients with acute decompensated heart failure without loop diuretic resistance. We reviewed two recent randomized controlled trials on the upfront use of acetazolamide and thiazide diuretics in acute decompensated heart failure, respectively. When the two trials on acetazolamide are considered together, adding oral or intravenous acetazolamide to loop diuretics in decompensated heart failure patients resulted in increased diuresis and natriuresis. However, the effects were significantly higher in patients with serum bicarbonate ≥ 27 mmol/L and those with higher baseline glomerular filtration rate (GFR). Similarly, when the two trials on thiazide diuretics are considered together, adding hydrochlorothiazide to loop diuretics in decompensated heart failure patients resulted in increased diuresis and weight loss. However, it increases the risk of impaired renal function. When all the trials are considered together, the upfront use of acetazolamide may be helpful in carefully selected patients, including patients with underlying elevated bicarbonate levels (≥ 27 mmol/L) and those with good renal function (GFR > 50). Conversely, though the upfront use of thiazide diuretic added to intravenous furosemide improved diuretic response in acute decompensated heart failure, it causes an increased risk of worsening renal function and lack of clear evidence of reducing hospital length of stay.

Obstructive sleep apnea as a risk factor for hypertension: a systematic review

Obstructive sleep apnea (OSA) is a progressively sleep-disordered breathing condition marked by bouts of upper airway obstruction during sleep. This systematic review aimed to comprehensively explore the lately available literature on OSA as an independent risk factor for developing hypertension (HTN). PubMed, SCOPUS, Web of Science, Science Direct, and Google Scholar were systematically searched for relevant literature. Rayyan QRCI was employed throughout this comprehensive process. This review included eight studies with a total of 12,473 parents, and 8,974 (71.9%) males. The total frequency of HTN in OSA cases was 5,643 (45.2%). The prevalence of HTN was rather high in OSA patients. Obesity and elevated bicarbonate levels were cofactors in the development of HTN in OSA patients. Children with OSA were three times more likely to develop HTN in the future. A growing number of OSA patients had or required HTN treatment. If treatment is not received, the patient becomes more vulnerable to cardiovascular and cerebrovascular diseases as a result of a self-perpetuating pathophysiological process. Even though there is a lot of research and strategies available for OSA cases who necessitate blood pressure decline, further choices are critically needed.

Effects of sex, age, and body mass index on serum bicarbonate.

Obesity hypoventilation syndrome (OHS) is often underdiagnosed, with significant morbidity and mortality. Bicarbonate, as a surrogate of arterial carbon dioxide, has been proposed as a screening tool for OHS. Understanding the predictors of serum bicarbonate could provide insights into risk factors for OHS. We hypothesized that the bicarbonate levels would increase with an increase in body mass index (BMI), since the prevalence of OHS increases with obesity. We used the TriNetX Research Network, an electronic health record database with de-identified clinical data from participating healthcare organizations across the United States, to identify 93,320 adults without pulmonary or advanced renal diseases who had serum bicarbonate and BMI measurements within 6 months of each other between 2017 and 2022. We used linear regression analysis to examine the associations between bicarbonate and BMI, age, and their interactions for the entire cohort and stratified by sex. We also applied a non-linear machine learning algorithm (XGBoost) to examine the relative importance of age, BMI, sex, race/ethnicity, and obstructive sleep apnea (OSA) status on bicarbonate. This cohort population was 56% women and 72% white and 80% non-Hispanic individuals, with an average (SD) age of 49.4 (17.9) years and a BMI of 29.1 (6.1) kg/m2. The mean bicarbonate was 24.8 (2.8) mmol/L, with higher levels in men (mean 25.2 mmol/L) than in women (mean 24.4 mmol/L). We found a small negative association between bicarbonate and BMI, with an expected change of -0.03 mmol/L in bicarbonate for each 1 kg/m2 increase in BMI (p < 0.001), in the entire cohort and both sexes. We found sex differences in the bicarbonate trajectory with age, with women exhibiting lower bicarbonate values than men until age 50, after which the bicarbonate levels were modestly higher. The non-linear machine learning algorithm similarly revealed that age and sex played larger roles in determining bicarbonate levels than the BMI or OSA status. Contrary to our hypothesis, BMI is not associated with elevated bicarbonate levels, and age modifies the impact of sex on bicarbonate.

Investigation of Physiologic Effect of Prolonged Consumption of Raphia Hookeri Fruits Pulp Aqueous Extract on Renal Functions of Male Wistar Rats

The aim of this study is to investigate the physiologic effect of prolonged consumption of Raphia Hookeri fruits pulp aqueous extract on renal functions of male wistar rats. A total of 32 male wistar rats of weight ranging from 130gram to 200grams were used. The extract was administered orally for each 4 groups except control (group1) for twenty-eight (28) days. Group 1 rats were given animal feed and water only, group 2 were given 500mg/kg body weight of the extract, group 3 were given 1000mg/kg body weight of the extract, group 4 were given 2000mg/kg body weight of extract. The statistical analysis done using mean and standard deviation, P value at ≤ 0.05 and results showed that the sodium ion levels in all the test groups were marginally raised when compared to group 1, potassium ion levels in all test groups had only non-significant variations when compared to both the control and test groups but in test groups were seen to be slightly reduced with respect to group 1. Groups 2, 3 and 4 indicated elevated bicarbonate ion but of all, it was most and significant in group 4 when compared to group 1. Chloride ion indicated non-uniform and non-significant changes when compared to both the control and test groups. Creatinine all indicates non-significant effects of the extract when compared to group 1. The increase observed in urea and creatinine indicates that kidney function would deteriorate as it prolongs which negatively alter the renal physiology of the male wistar rats.

Obesity Hypoventilation Syndrome and Postsurgical Outcomes in a Bariatric Surgery Cohort

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.Graphical abstract

Factors associated with pyloric hypertrophy severity and post-operative feeding and nutritional recovery in infantile hypertrophic pyloric stenosis

BackgroundTo examine factors that affect the severity of pyloric hypertrophy, post-operative feeding and nutritional recovery in infantile hypertrophic pyloric stenosis (IHPS). MethodsMedical records of infants diagnosed with IHPS at a single tertiary center between 2009 and 2018 were retrospectively reviewed. Clinical characteristics, biochemistry data and outcome were assessed for their association with the severity of pyloric hypertrophy and post-operative recovery. Nutritional recovery was assessed using weight-for-age status improvement after surgery. ResultsEighty-five patients were recruited in this study. The mean pre-operative weight-for-age percentile was 18.2. Elevated bicarbonate was positively correlated with symptom duration (p = 0.007). Pyloric muscle thickness was significantly correlated with age, weight, and symptom duration (p = 0.004, 0.003, 0.008, respectively). The mean weight-for-age percentile increased to 41.6 by post-operative weeks 6–8. Pyloric muscle thickness was negatively correlated with nutritional recovery by post-operative weeks 6–8 (p = 0.003). In multivariable analysis, pyloric length related to nutritional recovery at week 1–2 postoperatively (OR = 1.42, p = 0.030, 95% CI = 0.03–1.94), and pyloric muscle thickness related to nutritional recovery at week 6–8 postoperatively (OR = 4.08, p = 0.032, 95% CI = 1.13–14.7). ConclusionOur study indicated that favorable nutritional outcome and successful weight gain was observed 6–8 weeks after surgery in children with IHPS. Pyloric muscle thickness positively correlated with age, weight, symptom duration, and favorable nutritional recovery. Serum bicarbonate showed a positive correlation with symptom duration.

Groundwater fluoride across the Punjab plains of Pakistan and India: Distribution and underlying mechanisms

Chronic exposure from drinking well-water with naturally high concentrations of fluoride (F−) has serious health consequences in several regions across the world including South Asia, where the rural population is particularly dependent on untreated groundwater pumped from private wells. An extensive campaign to test 28,648 wells was conducted across the Punjab plains of Pakistan and India by relying primarily on field kits to document the scale of the problem and shed light on the underlying mechanisms. Groundwater samples were collected from a subset of 712 wells for laboratory analysis of F− and other constituents. A handful of sites showing contrasting levels of F− in groundwater were also drilled to determine if the composition of aquifer sediment differed between these sites. The laboratory data show that the field kits correctly classified 91% of the samples relative to the World Health Organization guideline for drinking water of 1.5 mg/L F−. The kit data indicate that 9% of wells across a region extending from the Indus to the Sutlej rivers were elevated in F− relative to this guideline. Field data indicate an association between the proportion of well-water samples with F− > 1.5 mg/L and electric conductivity (EC) > 1.5 mS/cm across six floodplains and six intervening doabs. Low Ca2+ concentrations and elevated bicarbonate (HCO3− > 500 mg/L) and sodium (Na+ > 200 mg/L) in high F− groundwater suggest regulation by fluorite. This could be through either the lack of precipitation or the dissolution of fluorite regulated by the loss of Ca2+ from groundwater due to precipitation of calcite and/or ion exchange with clay minerals. Widespread salinization of Punjab aquifers attributed to irrigation may have contributed to higher F− levels in groundwater of the region. Historical conductivity data suggest salinization has yet to be reversed in spite of changes in water resources management.

Water Quality Threats, Perceptions of Climate Change and Behavioral Responses among Farmers in the Ethiopian Rift Valley

This work aims to assess water quality for irrigated agriculture, alongside perceptions and adaptations of farmers to climate change in the Main Ethiopian Rift (MER). Climate change is expected to cause a rise in temperature and variability in rainfall in the region, reducing surface water availability and raising dependence on groundwater. The study data come from surveys with 147 farmers living in the Ziway–Shala basin and water quality assessments of 162 samples from groundwater wells and surface water. Most groundwater samples were found to be unsuitable for long term agricultural use due to their high salinity and sodium adsorption ratio, which has implications for soil permeability, as well as elevated bicarbonate, boron and residual sodium carbonate concentrations. The survey data indicate that water sufficiency is a major concern for farmers that leads to frequent crop failures, especially due to erratic and insufficient rainfall. An important adaptation mechanism for farmers is the use of improved crop varieties, but major barriers to adaptation include a lack of access to irrigation water, credit or savings, appropriate seeds, and knowledge or information on weather and climate conditions. Local (development) agents are identified as vital to enhancing farmers’ knowledge of risks and solutions, and extension programs must therefore continue to promote resilience and adaptation in the area. Unfortunately, much of the MER groundwater that could be used to cope with declining viability of rainfed agriculture and surface water availability, is poor in quality. The use of saline groundwater could jeopardize the agricultural sector, and most notably commercial horticulture and floriculture activities. This study highlights the complex nexus of water quality and sufficiency challenges facing the agriculture sector in the region, and should help decision-makers to design feasible strategies for enhancing adaptation and food security.

Five repeated maximal efforts of apneas increase the time to exhaustion in subsequent high-intensity exercise

Ten subjects were tested on a cycle ergometer to exhaustion with intensity corresponding to 150 % of their peak power output (TF150) under three conditions [C: base line measurement; PRE: after five repeated breath hold maneuvers (BH); and POST: after 5BH, preceded by two weeks of BH training]. Respiratory and blood measurements were carried out. Upon cessation of 5BH, subjects compared to C condition started TF150 with reduced arterialized blood pH (C:7.428±0.023, PRE:7.419±0.016, POST:7.398±0.021) and elevated bicarbonate concentration (mmol/l), ventilation (l/min) and oxygen uptake (ml/min) (C:28.4±1.5, PRE:29.9±1.2, POST:30.0±1.8; C:10.4±2.5, PRE:13.3±3.3, POST:15.6±5.6; C:333.0±113.8, PRE:550.1±131.1, POST:585.1±192.8, respectively). After TF150, subjects had significantly reduced pH and elevated ventilation, and oxygen uptake in PRE and POST, in comparison to the C condition. TF150 (sec) significantly improved after 5BH without being further affected by BH training (C:44.8±8.1, PRE:49.2±4.8, POST:49.3±8.2). Priming breath holds prior to middle-distance racing may improve performance.

Predictors of post discharge home oxygen therapy and Bilevel positive airway pressure therapy in stable hypercapnoea

Background: Hospital admission for acute exacerbation of COPD (AE-COPD) accounts for 70% of total costs of COPD treatment, and treatment cost is related to the duration of hospital stay. If post-discharge supportive care is required an extra cost will be added. The objectives of this study are to determine the predictive factors of post-discharge supportive care (Domiciliary oxygen, Bi-level positive airway pressure) in known COPD patients who got admitted with acute exacerbation. This is likely to help the treating physician to prime the family and plan an early discharge of the patient with supportive care instead of waiting for the patient to be off oxygen or BiPAP support. Methods: This is a retrospective study done at the pulmonology department of tertiary care hospital from January 2018-Jan 2019. Data sources were electronic medical records and the hospital discharge minimum data set. This study included 89 known COPD subjects who were not on prior supportive care (Long term oxygen therapy or home BIPAP) and were admitted for the management of acute exacerbation. Clinical parameters like symptoms at onset and the duration of symptoms (cough, fever, breathlessness, sputum production),comorbidities, initial blood investigations(complete blood counts, serum creatinine, arterial blood gas analysis, sputum culture reports)radiological findings, treatment details, pulmonary function test were evaluated with appropriate statistical tests. Parameters associated with post-discharge supportive care were evaluated. Results: A total of 89 patients were included in the study. Four patients were excluded because of the death. Presence of type II respiratory failure related findings like respiratory acidosis PH (P=0.02), elevated bicarbonate HCO3 (P=0.01), elevated carbon dioxide level PCO2 (p=0.007) in the ABG, and the requirement of non-invasive ventilation (P=0.00), Chest X-ray finding of hyperinflation (P=0.03) and treatment-related variables like prolonged duration of hospitalization (P&lt;0.01) were associated with post-discharge supportive care (Home oxygen therapy and BiPAP support) in univariate analysis. In the multivariate analysis hyperinflation (Odds ratio OR-4.73; 95% confidence interval; 1.37-16.33), noninvasive ventilation (OR-4.9; 95% CI: 1.29-18.47), and prolonged duration of hospitalization (OR-1.32; 95% CI: 1.05-1.66) remained significantly associated with post-discharge home oxygen therapy and home BiPAP therapy. Conclusion: This study results conclude that severe disease as marked by hyperinflation on Chest X-ray, presence of type II respiratory failure related changes in the ABG and requirement of non-invasive ventilation, and longer duration of hospitalization predicts the post-discharge supportive care. These findings can help the clinician to prepare for earlier discharge with post-discharge supportive care.

Activation of soluble AC10 induces cytoskeletal reorganisation

The cellular monolayer of the pulmonary endothelium forms a semi-selective barrier intersecting the vascular space, the underlying interstitium, and adjacent airspace. This endothelial barrier maintains tissue homeostasis critically regulating vessel permeability. Endothelial cAMP signals regulate endothelial permeability; however, cAMP signals are highly compartmentalized, such that cAMP signals generated by transmembrane adenylyl cyclase protect the barrier, while cAMP signals generated by soluble AC disrupt the barrier. Indeed, bicarbonate stimulation of soluble AC10 disrupts the endothelial barrier increasing permeability and is required for LPS-induced lung edema. Yet, how AC10 cAMP signals coordinate endothelial barrier regulation is unclear. The endothelial cytoskeleton alters cell shape which in turn regulates endothelial permeability. Thus, we hypothesized that bicarbonate stimulation of AC10 induces cytoskeletal remodeling. PMVECs were engineered to overexpress AC10 fused to a C-terminus hemagglutinin tag (HA). Gene and protein expression were controlled using a two-tier gene expression approach in which the doxycycline inducible promoter couples with a protein destabilizing variant of FKBP12 fused to the AC10-HA construct rendering the protein unstable in the absence of Shield1. In the presence of doxycycline and Shield1, AC10-HA protein began to appear 4-hours after induction and was absent in control cells. In this system, following addition of doxycycline and Shield1 and in the presence of elevated bicarbonate, whole cell cAMP increased over the same time course as protein expression while control cells showed no additional increase above normal bicarbonate stimulation. As cAMP increases above controls, endothelial cells begin to retract inducing inter-endothelial gaps between adjacent cells. This increase in inter-endothelial gaps was consistent with decreased resistance across the endothelial monolayer. To further address cytoskeletal mediated changes during AC10-induced endothelial barrier disruption, we examined actin cytoskeleton dynamics. Significant loss of the cortical actin rim and formation of actin stress fibers progress to complete actin cytoskeletal disruption by 24 hours. Interestingly, over the same course as the restructuring of the actin cytoskeleton, we detected phosphorylation of actin binding proteins, filamin and VASP, at PKA mediated sites. Thus, it appears that AC10 mediated pulmonary endothelial barrier disruption is coupled to actin remodeling.

There is more to an elevated bicarbonate.

Citation:Hadigal S, Ryals S, Wagner M, Berry R. There is more to an elevated bicarbonate. J Clin Sleep Med. 2021;17(1):111–112.

0675 Nocturnal Oxygen Supplementation With Positive Airway Pressure Therapy For Obesity Hypoventilation Syndrome: Clinical Predictors And Liberation From Oxygen

Abstract Introduction Obesity hypoventilation syndrome (OHS) is associated with a high morbidity and mortality. Many patients require nocturnal supplemental oxygen on top of positive airway pressure (PAP) therapy for hypoxemia independent of apneic events. We need to clinically identify patients likely to require nocturnal oxygen supplementation. Follow up is essential as with adequate control of sleep apnea, hypoxia improves and liberation from nocturnal oxygen supplementation may be achievable. Methods Researchers obtained a list of patients with coding diagnosis of OHS, seen at the Jefferson Sleep Center between November 2016 and September 2019. Patients with BMI of ≥ 30 and evidence of hypoventilation were included. Hypoventilation was defined as an elevated CO2 level of ≥ 45 mmHg on blood gas analysis, elevated serum bicarbonate level of ≥ 27 mmol/L or by evidence of nocturnal hypoventilation by AASM criteria on polysomnography. Patients with pulmonary and neuromuscular disorders were excluded Results Out of 189 patients reviewed, 36 met the inclusion and exclusion criteria. Nineteen patients (53%) required nocturnal oxygen supplementation. A higher serum bicarbonate level of 33 mmol/L against 30 mmol/L (p=0.0078) and a lower resting awake SaO2 of 89% versus 95% (p &amp;lt;0.01) were observed in the oxygen supplementation group. In polysomnographic data, the oxygen supplementation group had lower SaO2 nadir of 67% versus 73% (p=0.026) and had a longer time with SaO2 &amp;lt;88% at 238.2 minutes versus 65.5 minutes (p &amp;lt;0.01). Nine out of the 19 patients (47%) underwent nocturnal oximetry on PAP and room air. Of these, 4 patients (44%) were liberated from oxygen. Conclusion Fifty three percent of patients with OHS required nocturnal oxygen supplementation on top of PAP therapy. Higher serum bicarbonate level and lower resting awake SaO2 are potential clinical predictors of nocturnal oxygen supplementation. After nocturnal oximetry on PAP, 44% were successfully liberated from supplemental oxygen. Support

Loss of AC10 impairs neutrophil recruitment into the lung following Pseudomonas aeruginosa infection

Pseudomonas aeruginosa is a gram‐negative, opportunistic bacteria and a common cause of nosocomial pneumonia in critically ill patients that can progress to acute respiratory distress syndrome (ARDS). These patients have impaired gas exchange leading to hypoxia, altered blood pH and elevated bicarbonate. Bicarbonate, delivered into the cell via sodium bicarbonate cotransporters (NBCs), activates adenylyl cyclase 10 (AC10) to increase intracellular cAMP. Indeed, bicarbonate activation of AC10 is required for LPS‐induced lung endothelial permeability. Neutrophil recruitment into the airspaces plays a central role in the progression of ARDS. Recently, AC10 has been implicated in transendothelial emigration of neutrophils from the blood into the underlying tissue via CD99, a transmembrane protein critical for neutrophil recruitment. We sought to determine whether AC10 is necessary for neutrophil recruitment into the airspaces following P. aeruginosa intratracheal inoculation. Increasing doses of bacteria were introduced directly into the lung of wild type and AC10 and NBCn2 knockout mice. Bronchoalveolar lavage fluid (BALF) was recovered 24 hours later and examined for recruitment of polymorphonuclear cells (PMNs) into the airspaces. The number of PMNs recruited into the airspace following Pseudomonas inoculation increased with bacterial number and reached a maximum at a dose of 1E5 bacteria after which 100% of cells in the BALF were PMNs. Thus, doses upto 1E5 bacteria were used to examine the role of AC10 and NBCn2 in PMN recruitment into the airspace between wild type and knockout animals. Our data reveal a decreased number of PMNs in the BALF of both AC10 and NBCn2 knockout female mice; however, no difference in the number of PMNs recruited into the airspace was detected between male wild type and knockout animals. In addition, we confirmed the expression of CD99 in pulmonary microvascular endothelial cells and whole lung from both rat and mouse. Thus, CD99 is expressed in pulmonary endothelial cells and female mice utilize AC10 and NBCn2 to facilitate neutrophil recruitment into the airspace following a model of P. aeruginosa pneumonia.Support or Funding InformationNIH R01HL121513

Application of stable isotopes and dissolved ions for monitoring landfill leachate contamination.

We evaluated groundwater contamination by landfill leachate at a municipal landfill and characterized isotopic and hydrogeochemical evidence of the degradation and natural attenuation of buried organic matter at the study site. Dissolved ion content was generally much higher in the leachate than in the surrounding groundwater. The leachate was characterized by highly elevated bicarbonate and ammonium levels and a lack of nitrate and sulfate, indicating generation under anoxic conditions. Leachate δD and δ13CDIC values were much higher than those of the surrounding groundwater; some groundwater samples near the landfill showed a significant contamination by the leachate plume. Hydrochemical characteristics of the groundwater suggest that aquifer geology in the study area plays a key role in controlling the natural attenuation of leachate plumes in this oxygen-limited environment.

How does aquatic macrophyte Salvinia auriculata respond to nanoceria upon an increased CO2 source? A Fourier transform-infrared photoacoustic spectroscopy and chlorophyll a fluorescence study

With the continued increase of technological uses of cerium oxide nanoparticles (CeO2 NPs or nanoceria) and their unregulated disposal, the accumulation of nanoceria in the environment is inevitable. Concomitantly, atmospheric carbon dioxide (CO2) levels continue to rise, increasing the concentrations of bicarbonate ions in aquatic ecosystems. This study investigates the influence of CeO2 NPs (from 0 to 100 μgL−1) in the presence and absence of an elevated bicarbonate (HCO3−) ion concentration (1 mM), on vibrational biochemical parameters and photosystem II (PSII) activity in leaf discs of Salvinia auriculata. Fourier transform-infrared photoacoustic spectroscopy (FTIR-PAS) was capable of diagnostic use to understand biochemical and metabolic changes in leaves submitted to the CeO2 NPs and also detected interactive responses between CeO2 NPs and HCO3− exposure at the tissue level. The results showed that the higher CeO2 NPs levels in the presence of HCO3− increased the non-photochemical quenching (NPQ) and coefficient of photochemical quenching in dark (qPd) compared to the absence of HCO3. Moreover, the presence of HCO3− significantly decreased the NPQ at all levels of CeO2 NPs demonstrating that HCO3− exposure may change the non-radiative process involved in the operation of the photosynthetic apparatus. Overall, the results of this study are useful for providing baseline information on the interactive effects of CeO2 NPs and elevated HCO3− ion concentration on photosynthetic systems.

SUN-LB031 An Atypical Case of Diabetic Keto-Alkalosis with Severe Hypernatremic Hyperosmolarity in a Patient with Amphetamine Abuse

Introduction- Acid base disturbances have a complex interplay in Diabetic Ketoacidosis (DKA). Substance abuse in DKA is associated with more severe metabolic acidosis with higher acidosis-ketosis gap. Severe hypernatremia and alkalosis are rare in DKA but were exhibited in our case. Case- A 31-year-old female with Type 1 diabetes and schizophrenia was hospitalized after she was found to be minimally responsive at home. She had abdominal pain and polyuria since few days and wasn’t compliant with her medications. There was no history of vomiting, diarrhea, alkali ingestion, laxative or diuretic use. On admission, she was severely dehydrated, obtunded and only responsive to painful stimuli. Initial biochemical findings: serum glucose 1323 mg/dl (n 70-140 mg/dl), sodium 135 mEq/L (n 136-148 mEq/L, corrected sodium 154, bicarbonate 32 mEq/L (n 22-28 mEq/L), serum osmolality 379 (n 275-295 mOsm/Kg), beta hydroxybutyrate 62.56 mg/dl (n <=4.17 mg/dl), anion gap 30 (n 12-16) and delta gap of 24. Venous blood gas showed: pH-7.40 (n 7.31-7.41), pCO2-62 (n 41-51), HCO3-38.4 (23-27). She was adequately managed and was fully awake and alert with closed anion-gap within 24 hours of admission. Serum sodium initially peaked to 163 but normalized over the next 36-42 hours. She was also admitted with HHS (Hyperglycemic Hyperosmolar State) 3 months before and 1 month after this admission. Urine drug screen was positive for amphetamines in all 3 admissions. Discussion- Our patient exhibited mixed metabolic acidosis (elevated anion gap, ketonemia), metabolic alkalosis (elevated bicarbonate, elevated delta gap) and compensatory respiratory acidosis. Osmotic diuresis due to glycosuria and amphetamine abuse led to severe volume depletion and bicarbonate reabsorption leading to severe contraction alkalosis. Studies have shown that methamphetamine use leads to elevated plasma cortisol and corticosterone levels via hyper-activation of the hypothalamic-pituitary-adrenal axis. Ecstasy use has been shown to cause an acute increase in cortisol levels of around 150% in sedentary humans and 800% in dance clubbers. Excess glucocorticoids promote Hᶧ secretion from kidneys via mineralocorticoid receptors contributing to alkalosis. DKA/HHS patients usually present with eunatremia/hyponatremia. Adult schizophrenics who receive psychostimulants have been shown to develop polydipsia and hyponatremia. Ecstasy intoxication can precipitate both DKA and hyponatremia in Type1 diabetics. Combined DKA/HHS and hypernatremic hyperosmolarity has been reported due to huge intake of sugar-rich carbonated beverages to quench thirst especially in pediatric population. There is frequent association between decompensated diabetes and illicit drug use. Substance abuse should be suspected in young Type 1 diabetics presenting with recurrent hyperglycemic emergencies especially with atypical biochemical features. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.