Magnesium homeostasis in deoxygenated sickle erythrocytes is modulated by endothelin-1 via Na+ /Mg2+ exchange.

Painful crises in sickle cell disease (SCD) are associated with increased plasma cytokines levels, including endothelin-1 (ET-1). Reduced red cell magnesium content, mediated in part by increased Na+ /Mg2+ exchanger (NME) activity, contributes to erythrocyte K+ loss, dehydration and sickling in SCD. However, the relationship between ET-1 and the NME in SCD has remained unexamined. We observed increased NME activity in sickle red cells incubated in the presence of 500 nM ET-1. Deoxygenation of sickle red cells, in contrast, led to decreased red cell NME activity and cellular dehydration that was reversed by the NME inhibitor, imipramine. Increased NME activity in sickle red cells was significantly blocked by pre-incubation with 100 nM BQ788, a selective blocker of ET-1 type B receptors. These results suggest an important role for ET-1 and for cellular magnesium homeostasis in SCD. Consistent with these results, we observed increased NME activity in sickle red cells of three mouse models of sickle cell disease greater than that in red cells of C57BL/J6 mice. In vivo treatment of BERK sickle transgenic mice with ET-1 receptor antagonists reduced red cell NME activity. Our results suggest that ET-1 receptor blockade may be a promising therapeutic approach to control erythrocyte volume and magnesium homeostasis in SCD and may thus attenuate or retard the associated chronic inflammatory and vascular complications of SCD.

Reduction in Serum Magnesium Levels and Renal Function Are Associated with Increased Mortality in Obese COVID-19 Patients.

Several studies provide evidence that obesity is a significant risk factor for adverse outcomes in coronavirus disease 2019 (COVID-19). Altered renal function and disturbances in magnesium levels have been reported to play important pathophysiological roles in COVID-19. However, the relationship between obesity, renal function, circulating magnesium levels, and mortality in patients with COVID-19 remains unclear. In this retrospective cohort study, we characterized 390 hospitalized patients with COVID-19 that were categorized according to their body mass index (BMI). Patients were clinically characterized and biochemical parameters, renal function, and electrolyte markers measured upon admission. We found that in patients who died, BMI was associated with reduced estimated glomerular filtration rate (eGFR, Rho: −0.251, p = 0.001) and serum magnesium levels (Rho: −0.308, p < 0.0001). Multiple linear regression analyses showed that death was significantly associated with obesity (p = 0.001). The Cox model for obese patients showed that magnesium levels were associated with increased risk of death (hazard ratio: 0.213, 95% confidence interval: 0.077 to 0.586, p = 0.003). Thus, reduced renal function and lower magnesium levels were associated with increased mortality in obese COVID-19 patients. These results suggest that assessment of kidney function, including magnesium levels, may assist in developing effective treatment strategies to reduce mortality among obese COVID-19 patients.

Disordered Glucose Levels Are Associated with Xanthine Oxidase Activity in Overweight Type 2 Diabetic Women.

Oxidative stress plays an important role in vascular complications observed in patients with obesity and Type 2 Diabetes (T2D). Xanthine oxidase (XO) breaks down purine nucleotides into uric acid and contributes to the production of reactive oxygen species (ROS). However, the relationship between XO activity and glucose homeostasis in T2D subjects with obesity is unclear. We hypothesized that disordered glucose levels are associated with serum XO activity in overweight women and men with T2D and without hyperuricemia. We studied serum XO activity in women and men with and without T2D. Our results show that serum XO activity was greater in T2D patients with body mass index (BMI) ≥ 25 kg/m2 than in those with BMI < 25 kg/m2 (p < 0.0001). Sex-based comparative analyses of overweight T2D patients showed that serum XO activity correlated with homeostasis model assessment of ß-cell function (HOMA-ß), fasting plasma glucose (FPG), and hemoglobin A1C in overweight T2D women but not in overweight T2D men. In addition, as compared to overweight T2D men, women had higher high-sensitivity C-reactive protein (hs-CRP) levels. However, overweight T2D men had higher XO activity and uric acid levels than women. Our results suggest that XO activity is higher in overweight T2D patients, especially in men, but is more sensitive to disordered glucose levels in overweight women with T2D.

The effects of biological sex and cardiovascular disease on COVID-19 mortality.

Cardiovascular disease (CVD) is a common comorbidity observed in patients with coronavirus disease 2019 (COVID-19), which is associated with increased severity and mortality. However, the effects of biological sex on CVD-associated mortality in patients with COVID-19 are poorly established, particularly among Hispanic/Latin Americans. We examined the association of preexisting CVD with COVID-19 mortality in hospitalized Latin American men and women. This multicenter study included Mexican patients hospitalized with a positive diagnosis of COVID-19. The main outcome was in-hospital mortality. Multivariable regression analyses were used to calculate the adjusted odds ratio with 95% confidence interval for mortality in women and men. Of 81,400 patients with a positive diagnosis for SARS-CoV-2 infection, 28,929 (35.54%) hospitalized patients were evaluated. Of these, 35.41% (10,243) were women. In-hospital death was higher in men than in women. In relation to CVD between the sexes, women had a higher incidence of CVD than men (4.69 vs. 3.93%, P = 0.0023). The adjusted logistic regression analyses showed that CVD was significantly associated with COVID-19 mortality in women but not men. We then stratified by sex according to age <52 and ≥52 yr old. Similar significant association was also found in prespecified analysis in women ≥52 yr old but not in men of similar age. We conclude that CVD's effect on mortality among patients hospitalized with COVID-19 is dependent on biological sex and age in this Latin American cohort. These results suggest that therapeutic strategies for Latin American women with CVD and COVID-19 should include particular attention to their cardiovascular health.NEW & NOTEWORTHY CVD's effect on COVID-19 mortality is dependent on biological sex and age. CVD in women but not men with COVID-19 is associated with significantly unfavorable outcomes.

Disordered glycemic control in women with type 2 diabetes is associated with increased TNF receptor-2 levels.

BACKGROUND: Evidence implicates tumor necrosis factor (TNF) in the pathophysiology of Type 2 Diabetes (T2D) through unclear mechanisms. We hypothesized that disordered glycemic control leads to TNF activation and increases in soluble-TNF (sTNF) and its receptors-1 (sTNFR1) and -2 (sTNFR2). METHODS: We characterized 265 T2D and non-diabetic Latin American subjects and assessed the relationship between the TNF system and fasting plasma glucose (FPG), hemoglobin-A1C (A1C), insulin (FPI), C-peptide and HOMA-Beta. RESULTS: sTNF and sTNFR2 but not sTNFR1 levels were higher in T2D than non-diabetics (P<0.0001). In T2D, sTNFR2 was associated with A1C and C-peptide (R2=0.354, b=0.504, P<0.0001; b=0.167, P=0.049). Also, T2D patients with disordered glycemic control had increased sTNFR2 levels that correlated with FPG (Rho:0.393, P<0.001), A1C (Rho:0.451, P<0.001) and HOMA-Beta (Rho:-0.308, P=0.005); events not observed in T2D patients with adequate glycemic control. Furthermore, sex-based comparative analyses of T2D patients showed that women compared to men had higher sTNFR2 levels (P=0.017) that correlated with FPG, A1C, FPI and HOMA-Beta. CONCLUSIONS: Disordered glycemic control is associated with sTNF and sTNFR2. sTNFR2 levels were higher in T2D women than men. Thus, increased sTNFR2 levels may be an important biomarker for disordered glucose and inflammatory complications in T2D patients and women in particular.

Renal function, serum magnesium levels and mortality in COVID-19 patients with type 2 diabetes.

Patients with type 2 diabetes (T2D) and Latin American subjects in particular are at an increased risk of developing severe COVID-19 and mortality. Altered renal function and lower magnesium levels have been reported to play important roles in the pathophysiology of T2D. The aim of the study was to investigate the relationship between renal function, serum magnesium levels and mortality in T2D patients with COVID-19. In this retrospective study, we characterized 118 T2D and non-diabetic subjects hospitalized with COVID-19. Patients were clinically characterized and electrolyte, renal function and inflammatory markers were evaluated. Patients were grouped according to their estimated glomerular filtration rate (eGFR <60 mL/min per 1.73 m2). T2D patients had lower eGFR and serum magnesium levels when compared to non-diabetics (59.7 ± 32.8 vs. 78.4 ± 33.8 mL/min per 1.73 m2, P = 0.008 and 1.9 ± 0.3 vs. 2.1 ± 0.3 mEq/L, P = 0.012). Survival was worse in T2D patients with eGFR levels less than 60 mL/min per 1.73 m2 as estimated by Kaplan-Meier analyses (log-rank test <0.0001). The Cox model for T2D patients showed that eGFR (HR 0.970, 95% CI 0.949 to 0.991, P = 0.005) and magnesium (HR 8.025, 95% CI 1.226 to 52.512, P = 0.030) were associated with significantly increased risk of death. Reduced eGFR and magnesium levels were associated with increased mortality in our population. These results suggest that early assessment of kidney function, including magnesium levels, may assist in developing effective treatment strategies to reduce morbidity and mortality among Latin American COVID-19 patients with T2D.

C-Peptide Is a Sensitive Indicator for the Diagnosis of Metabolic Syndrome in Subjects from Central Mexico.

BACKGROUND: Metabolic Syndrome (MetS) is associated with elevated risk for developing diabetes and cardiovascular disease. A key component of MetS is the development of insulin resistance (IR). The homeostatic model assessment (HOMA) model can determine IR by using insulin or C-peptide concentrations; however, the efficiency of insulin and C-peptide to determine MetS has not been compared. The aim of the study was to compare the efficiency of C-peptide and insulin to determine MetS in Mexicans. METHODS: Anthropometrics, glucose, insulin, C-peptide, triglycerides, and high-density lipoproteins were determined in 156 nonpregnant females and 114 males. Subjects were separated into normal or positive for MetS. IR was determined by the HOMA2 calculator using insulin or C-peptide. Correlations were calculated using the Spearman correlation coefficient (ρ). Differences between correlations were determined by calculating Steiger's Z. The sensitivity was determined by the area under receiver operating characteristics curve (AUC) analysis. RESULTS: Independent of the MetS definition [Adult Treatment Panel III (ATP III), International Diabetes Federation (IDF), or World Health Organization (WHO)], C-peptide and insulin were significantly higher in MetS subjects (P < 0.05). C-peptide and insulin correlated with all components of MetS; however, for waist circumference, waist-to-hip ratio, and fasting plasma glucose, C-peptide correlated better than insulin (P < 0.05). Moreover, C-peptide (AUC = 0.72-0.78) was a better marker than insulin (AUC = 0.62-0.72) for MetS (P < 0.05). Finally, HOMA2-IR calculated with C-peptide (AUC = 0.80-0.84) was more accurate than HOMA2-IR calculated with insulin (AUC = 0.68-0.75, P < 0.05) at determining MetS. CONCLUSION: C-peptide is a strong indicator of MetS. Since C-peptide has recently emerged as a biomolecule with significant importance for inflammatory diseases, monitoring C-peptide levels will aid clinicians in preventing MetS.

Obese first-degree relatives of patients with type 2 diabetes with elevated triglyceride levels exhibit increased ß-cell function.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is characterized as a disease continuum that is marked by metabolic changes that are present for several years, sometimes well before frank diagnosis of T2DM. Genetic predisposition, ethnicity, geography, alterations in BMI, and lipid profile are considered important markers for the pathogenesis of T2DM through mechanisms that remain unresolved and controversial. The aim of this study was to investigate the relationship between triglycerides (TGs) and ß-cell function, insulin resistance (IR), and insulin sensitivity (IS) in obese first-degree relatives of patients with T2DM (FDR-T2DM) among subjects from central Mexico with normal glucose tolerance (NGT). METHODS: We studied 372 FDR-T2DM subjects (ages,18-65) and determined body mass index (BMI), fasting plasma glucose (FPG), oral glucose tolerance test (OGTT), insulin, and TGs levels. Subjects were categorized based on glycemic control [NGT, prediabetes (PT2DM), or T2DM]. NGT subjects were further categorized by BMI [normal weight (Ob-) or obese (Ob+)] and TGs levels (TG-, <150 mg/dL, or TG+, ≥150 mg/dL). ß-cell function, IR, and IS were determined by the homeostasis model assessment of ß-cell function (HOMA2-ß), homeostasis model assessment of insulin resistance (HOMA2-IR), and Quantitative Insulin Sensitivity Check Index (QUICKI) indices, respectively. RESULTS: The obese subjects with elevated TGs levels had 21%-60% increased ß-cell function when compared to all groups (P<0.05). In addition, this group had insulin levels, IS, and IR similar to PT2DM. Furthermore, only in obese subjects did TGs correlate with ß-cell function (ρ=0.502, P<0.001). CONCLUSION: We characterized FDR-T2DM subjects from central Mexico with NGT and revealed a class of obese subjects with elevated TGs and ß-cell function, which may precede PT2DM.

Early decrease of insulin sensitivity in offspring of individuals with type 2 diabetes. The Mexican Diabetes Prevention Study.

BACKGROUND AND AIMS: Defects in insulin sensitivity (IS) and insulin secretion have been recognized as risk factors for type 2 diabetes (T2D) and its complications. We undertook this study to establish the relationship between healthy type 2 diabetic offspring (OFD) from a Mexican population with IS. METHODS: A total of 602 Mexican subjects, 359 first-degree offspring of T2D (OFD+) and 243 first-degree non-offspring of T2D (OFD-) were classified as young adults (age range, 18-44 years) and middle-aged adults (age range, 45-65 years). Groups were clinically and biochemically characterized. Quantitative insulin sensitivity check index (QUICKI) was used to estimate IS and the homeostasis model assessment B (HOMA-B) was used to estimate B cell function. RESULTS: IS decreased significantly (p <0.05) in OFD+ middle-aged (QUICKI 0.330 ± 0.03) compared with OFD- (0. 370 ± 0.03). Middle-aged adults (OFD+) had the highest prevalence of increased fasting insulin levels (FIL) (13.6%) and decreased IS (22.9%) compared with OFD- groups (3.2%). A binary regression analysis showed the association of OFD+ with increased FIL (odds ratio [OR], 3.71; 95% confidence interval [95% CI], 1.68-8.2; p = 0.001), and QUICKI (OR, 10.87; 95% CI, 2.36-44.69; p <0.01) adjusted by gender, age, and obesity. CONCLUSIONS: Our results suggest that decreased IS itself could be recognized as one of the earliest detectable abnormalities in middle-aged adults. Moreover, prevalence increases with age and is associated with type 2 diabetic offspring, regardless of obesity.

Islet amyloid polypeptide gene variation (IAPP) and the risk of incident type 2 diabetes mellitus: the Women's Genome Health Study.

BACKGROUND: Islet amyloid polypeptide (IAPP) gene variation has recently been implicated in type 2 diabetes mellitus (T2D). However, to date, no prospective epidemiological data are available. METHODS: The association between 10 IAPP tag-single nucleotide polymorphisms (tSNPs) and incident T2D was investigated in 22,715 Caucasian participants of the prospective Women's Genome Health Study. All were free of known cardiovascular disease, cancer, and diabetes at baseline. During a 13-year follow-up period, 1445 participants developed an incident T2D. Multivariable Cox regression analysis was performed to investigate the relationship between genotypes and T2D risk. Haplotype-based analysis was also performed. RESULTS: No evidence for an association of any of the tSNPs tested or haplotypes thereof with T2D risk. CONCLUSIONS: If corroborated in other large, prospective studies, the present findings further suggest that the IAPP gene locus may not be useful predictor for T2D risk assessment.

Clinical forms of Trypanosoma cruzi infected individuals in the chronic phase of Chagas disease in Puebla, Mexico.

In Mexico, despite the relatively high seroprevalence of Trypanosoma cruzi infection in humans in some areas, reported morbidity of Chagas disease is not clear. We determined clinical stage in 71 individuals seropositive to T. cruzi in the state of Puebla, Mexico, an area endemic for Chagas disease with a reported seroprevalence of 7.7%. Diagnosis of Chagas disease was made by two standardized serological tests (ELISA, IHA). Individuals were stratified according to clinical studies. All patients were submitted to EKG, barium swallow, and barium enema. Groups were identified as indeterminate form (IF) asymptomatic individuals without evidence of abnormalities (n = 34 cases); those with gastrointestinal alterations (12 patients) including symptoms of abnormal relaxation of the lower esophageal sphincter and absent peristalsis in the esophageal body, grade I megaesophagus, and/or megacolon; patients with clinical manifestations and documented changes of chronic Chagas heart disease who were subdivided as follows: mild (8 patients)--mild electrocardiographic changes of ventricular repolarization, sinus bradychardia); moderate (6 patients)--left bundle branch block, right bundle branch block associated with left anterior fascicular block); severe (8 patients)--signs of cardiomegaly, dilated cardiomyopathy); and the associated form (3 cases) that included presence of both cardiomyopathy and megaesophagus. These data highlight the importance of accurate evaluation of the prevalence and clinical course of Chagas disease in endemic and non-endemic areas of Mexico.

Clinical forms of Trypanosoma cruzi infected individuals in the chronic phase of Chagas disease in Puebla, Mexico

In Mexico, despite the relatively high seroprevalence of Trypanosoma cruzi infection in humans in some areas, reported morbidity of Chagas disease is not clear. We determined clinical stage in 71 individuals seropositive to T. cruzi in the state of Puebla, Mexico, an area endemic for Chagas disease with a reported seroprevalence of 7.7 percent. Diagnosis of Chagas disease was made by two standardized serological tests (ELISA, IHA). Individuals were stratified according to clinical studies. All patients were submitted to EKG, barium swallow, and barium enema. Groups were identified as indeterminate form (IF) asymptomatic individuals without evidence of abnormalities (n = 34 cases); those with gastrointestinal alterations (12 patients) including symptoms of abnormal relaxation of the lower esophageal sphincter and absent peristalsis in the esophageal body, grade I megaesophagus, and/or megacolon; patients with clinical manifestations and documented changes of chronic Chagas heart disease who were subdivided as follows: mild (8 patients) - mild electrocardiographic changes of ventricular repolarization, sinus bradychardia); moderate (6 patients) - left bundle branch block, right bundle branch block associated with left anterior fascicular block); severe (8 patients) - signs of cardiomegaly, dilated cardiomyopathy); and the associated form (3 cases) that included presence of both cardiomyopathy and megaesophagus. These data highlight the importance of accurate evaluation of the prevalence and clinical course of Chagas disease in endemic and non-endemic areas of Mexico.