DNA Methylation-Mediated Mfn2 Gene Regulation in the Brain: A Role in Brain Trauma-Induced Mitochondrial Dysfunction and Memory Deficits.

Repeated mild traumatic brain injuries (rMTBI) affect mitochondrial homeostasis in the brain. However, mechanisms of long-lasting neurobehavioral effects of rMTBI are largely unknown. Mitofusin 2 (Mfn2) is a critical component of tethering complexes in mitochondria-associated membranes (MAMs) and thereby plays a pivotal role in mitochondrial functions. Herein, we investigated the implications of DNA methylation in the Mfn2 gene regulation, and its consequences on mitochondrial dysfunction in the hippocampus after rMTBI. rMTBI dramatically reduced the mitochondrial mass, which was concomitant with decrease in Mfn2 mRNA and protein levels. DNA hypermethylation at the Mfn2 gene promoter was observed post 30 days of rMTBI. The treatment of 5-Azacytidine, a pan DNA methyltransferase inhibitor, normalized DNA methylation levels at Mfn2 promoter, which further resulted into restoration of Mfn2 function. The normalization of Mfn2 function was well correlated with recovery in memory deficits in rMTBI-exposed rats. Since, glutamate excitotoxicity serves as a primary insult after TBI, we employed in vitro model of glutamate excitotoxicity in human neuronal cell line SH-SY5Y to investigate the causal epigenetic mechanisms of Mfn2 gene regulation. The glutamate excitotoxicity reduced Mfn2 levels via DNA hypermethylation at Mfn2 promoter. Loss of Mfn2 caused significant surge in cellular and mitochondrial ROS levels with lowered mitochondrial membrane potential in cultured SH-SY5Y cells. Like rMTBI, these consequences of glutamate excitotoxicity were also prevented by 5-AzaC pre-treatment. Therefore, DNA methylation serves as a vital epigenetic mechanism involved in Mfn2 expression in the brain; and this Mfn2 gene regulation may play a pivotal role in rMTBI-induced persistent cognitive deficits. Closed head weight drop injury method was employed to induce repeated mild traumatic brain (rMTBI) in jury in adult, male Wistar rats. rMTBI causes hyper DNA methylation at the Mfn2 promoter and lowers the Mfn2 expression triggering mitochondrial dysfunction. However, the treatment of 5-azacytidine normalizes DNA methylation at the Mfn2 promoter and restores mitochondrial function.

Association of Diet-dependent Systemic Acid Load, Renal Function, and Serum Albumin Concentration.

OBJECTIVE: Inflammation may be present with chronic kidney disease CKD and diet composition high in protein intake and fats may affect inflammation thereby impacting kidney health. We investigated whether acid load estimated from urine measures is associated with kidney function decline and whether the effect of acid load on an inflammatory marker, serum albumin, is a pathway to this association. METHODS: We studied 188 postmenopausal women in a randomized clinical trial of potassium bicarbonate treatment for up to 36 months. Twenty-four-hour urine and arterialized blood collections were done at baseline and at subsequent follow-up visits at 3 months interval. Acid load was estimated from potential renal acid load calculated using urinary measures of chloride, phosphate, sodium, potassium, calcium, and magnesium (UPRAL). Mixed effects model with random-intercept and slope was used to estimate subjects' annual decline rate in creatinine clearance (CrCl), and the association between (i) UPRAL and serum albumin and (ii) serum albumin and CrCl, adjusting for age, body mass index, systolic BP, and glucose. A Cox proportional regression model was used to study the relative hazard (RH) for rapid progression of kidney function decline (defined as loss of ≥5 mL/min CrCl/yr based on the last CrCl in the rolling window) with UPRAL, adjusting for the potential covariates and baseline CrCl. RESULTS: A 25 mEq/day increase in UPRAL was inversely associated with serum albumin (Adjusted ß[95% CI]: -0.02[-0.09;-0.001). During a mean follow-up of 28 months, 19 women (10%) had a rapid decline in kidney function. For each 25 mEq/day increase in UPRAL, the risk of a rapid decline in CrCl increased by 17% (95% CI: 1.06-1.28). On adjustment for potential confounders, the risk attenuated to 5% (1.02-1.14). Mediation analysis indicated that of the total effect of the association between UPRAL and CrCl, the proportion mediated by serum albumin increased to 0.346 (i.e. 34.6%). CONCLUSION: Higher UPRAL was associated with lower serum albumin as well as greater kidney function decline in postmenopausal women. Our findings suggest inflammatory response may exert a modulatory effect on the association of UPRAL and kidney function and might be a potential pathway explaining the effects of systemic acid load on progression of kidney failure.

Riverine connectivity influences the phytoplankton ecology in the open floodplain wetland of the lower river Ganga.

The river Ganga has several floodplain wetlands that support its ecology and ecosystem. Phytoplankton is an important component of the aquatic ecosystem, which plays an important role as a bioindicator for the assessment of aquatic health. The present study was conducted between 2018 and 2019 to understand the seasonal variation in the phytoplankton diversity of the Charaganga wetland and, parallelly, in the river Ganga in Nabadweep, India. The study explains how riverine connectivity affects the structure of the algal community in the wetland ecosystem. In the study, it has been observed that in the wetland, maximum mean phytoplankton density was noticed during pre-monsoon, i.e., 4079 unit l-1 followed by post-monsoon 3812 unit l-1 and monsoon 550 unit l-1, respectively. In the river system, the phytoplankton density varied from 78 unit l-1 to 653 unit l-1 seasonally, i.e., highest during monsoon and lowest during pre-monsoon. In both the ecosystems, i.e., wetland and river, the supreme influential group was Cyanophyceae followed by diatoms. One-way ANOVA showed a significant variation (p > 0.05) of three algal groups of phytoplankton (Bacillariophyceae, Coscinodiscophyceae, Chlorophyceae) in the river, while in the wetland, no significant variation (p > 0.05) was found among the other algal groups. The observed higher Shannon and Margalef's species richness value in the wetland was observed than in the river defines the significance and importance of the wetland ecosystem, which may support the growth and conservation of various aquatic organisms as well. The study highlighted that the influencing abiotic factors like water temperature, dissolved oxygen, pH, and nutrients have affected the phytoplankton community in both the water bodies, i.e., wetland and river. We concluded that river connectivity is required to restore the biotic flora of the wetland ecosystem.

An in silico scientific basis for LL-37 as a therapeutic for Covid-19.

A multi-pronged approach with help in all forms possible is essential to completely overcome the Covid-19 pandemic. There is a requirement to research as many new and different types of approaches as possible to cater to the entire world population, complementing the vaccines with promising results. The need is also because SARS-CoV-2 has several unknown or variable facets which get revealed from time to time. In this work, in silico scientific findings are presented, which are indicative of the potential for the use of the LL-37 human anti-microbial peptide as a therapeutic against SARS-CoV-2. This indication is based on the high structural similarity of LL-37 to the N-terminal helix, with which the virus interacts, of the receptor for SARS-CoV-2, Angiotensin Converting Enzyme 2. Moreover, there is positive prediction of binding of LL-37 to the receptor-binding domain of SARS-CoV-2; this is the first study to have described this interaction. In silico data on the safety of LL-37 are also reported. As Vitamin D is known to upregulate the expression of LL-37, the vitamin is a candidate preventive molecule. This work provides the possible basis for an inverse correlation between Vitamin D levels in the body and the severity of or susceptibility to Covid-19, as widely reported in literature. With the scientific link put forth herein, Vitamin D could be used at an effective, medically prescribed, safe dose as a preventive. The information in this report would be valuable in bolstering the worldwide efforts to eliminate the pandemic as early as possible.

A decoy strategy to activate the immune system.

An approach comprising a novel fusion protein and inactivated virus, as a more efficacious vaccine against invading viruses is presented, using SARS-CoV-2 as a most prominent example. The fusion protein consists of the Hepatitis B surface antigen (HBsAg) conjugated to the N-terminal helix (NTH) of Angiotensin-Converting Enzyme 2 (ACE2), which is the receptor for SARS-CoV-2. For vaccination, this fusion protein is to be administered together with the whole killed virus. The NTH would bind to the Receptor Binding Domain (RBD) of the Spike protein of the killed virus. Due to HBsAg acting as a decoy, immune responses would be mounted. Neutralizing antibodies (NAbs) pre-existing in people already vaccinated with the recombinant Hepatitis B vaccine, fresh production of NAbs, and NAbs produced by memory B cells would bind to the HBsAg. This would lead to "presentation" of the killed virus to elements of the immune system at close range. Also, there would be enhanced opsonization and effective antigen presentation. This two-component vaccine could be a platform strategy, wherein HBsAg could be linked to the part of the cellular receptor that any new intractable virus binds to, and is administered together with whole inactivated virus. Now, the same fusion protein, administered by itself to persons with infection, would have therapeutic action, yet by harnessing elements of the immune system. NAbs would bind to the fusion protein as above, the NTH of which would bind to the RBDs of the infecting virus, which, in effect would be neutralized.

Dietary Factors and Prevention: Risk of End-Stage Kidney Disease by Fruit and Vegetable Consumption.

BACKGROUND: The association between fruit and vegetable (FV) intake and the risk of end-stage kidney disease (ESKD) has not been examined in the general population and fully explored in chronic kidney disease (CKD). We prospectively evaluated this relationship in US representative sample of adults and evaluated consistency by the presence or absence, and severity, of CKD. METHODS: We used data from the Third National Health and Nutrition Examination Survey (1988-1994) linked with the US Renal Data System, including 14,725 adults aged ≥20 years and with follow-up for ESKD through 2008. Daily FV intake was ascertained using a food frequency questionnaire. We examined the association between selected categories of FV intake and ESKD using a Fine Gray competing risk model adjusting for sociodemographics, lifestyle, clinical and nutritional factors, estimated glomerular filtration rate, and albuminuria. We evaluated whether risk varied in individuals with severe versus any CKD. RESULTS: 230 participants (1.5%) developed ESKD during follow-up. In the adjusted model, compared to highest intake, those in lowest categories of FV intake had a higher risk of ESKD, for <2 times/day (1.45 [1.24-1.68], 2 to <3 times/day (1.40 [1.18-1.61]), 3 to <4 times/day (1.25 [1.04-1.46]), and 4 to <6 times/day (1.14 [0.97-1.31]). There was suggestion of heterogeneity (p for interaction = 0.03) with possible stronger inverse association in patients with CKD than those without CKD. After stratification, we obtained similar strong inverse association when we examined ESKD incidence across intake of FVs in participants with CKD stages 1-4 (n = 5,346) and specifically in those with CKD stages 3-4 (n = 1,084). CONCLUSIONS: Low intake of FVs was associated with higher risk of ESKD in US adults with and without CKD, supporting an emerging body of literature on the potential benefits of plant-rich diets for prevention of ESKD.

Nanotized curcumin-benzothiophene conjugate: A potential combination for treatment of cerebral malaria.

The declining effectiveness of the available antimalarial drugs due to drug resistance requires a continued effort to develop new therapeutic approaches. In this context, combination therapies hold a great promise for developing effective first-line antimalarial treatments for reducing malaria mortality. The present study explores the antimalarial efficacy of nanotized formulation of curcumin in combination with benzothiophene compound 6 (3-bromo-N-(4-fluorobenzyl)-benzo[b]thiophene-2-carboxamide) with a view to achieve better efficacy at a very low dose in comparison to that accomplished with monotherapy alone. Herein, we formulated nanotized conjugate of curcumin and compound 6 (cur-compound 6) in the size range of 30-90 nm as observed via TEM, AFM and DLS analysis in the study. The nanotized preparation was found to be readily dispersible in water, physically and chemically stable and exhibited sustained release profile of both curcumin and compound 6 till 48 hr. Treatment of P. falciparum parasites with the nanotized conjugate for 24 hr resulted in rapid clearance of the parasites. Furthermore, P. berghei infected mice treated with nanotized conjugate formulation survived till 90 days with complete eradication of the parasites from RBC. This improved efficacy of the nanotized formulation was possible because of the increased absorption of the compounds via oral administration owing to enhanced dispersibility of the formulation in aqueous medium. Moreover, an improved oral bioavailability of the nanotized formulation lowered the dosage at which the pharmacological effect was achieved while avoiding any observable adverse harmful side effects.

CKD Awareness Among US Adults by Future Risk of Kidney Failure.

RATIONALE & OBJECTIVE: Persons with chronic kidney disease (CKD) are often unaware of their disease status. Efforts to improve CKD awareness may be most effective if focused on persons at highest risk for progression to kidney failure. STUDY DESIGN: Serial cross-sectional surveys. SETTING & PARTICIPANTS: Nonpregnant adults (aged≥20 years) with CKD glomerular filtration rate categories 3-4 (G3-G4) who participated in the National Health and Nutrition Examination Survey from 1999 to 2016 (n = 3,713). PREDICTOR: 5-year kidney failure risk, estimated using the Kidney Failure Risk Equation. Predicted risk was categorized as minimal (<2%), low (2%-<5%), intermediate (5%-<15%), or high (≥15%). OUTCOME: CKD awareness, defined by answering "yes" to the question "Have you ever been told by a doctor or other health professional that you had weak or failing kidneys?" ANALYTICAL APPROACH: Prevalence of CKD awareness was estimated within each risk group using complex sample survey methods. Associations between Kidney Failure Risk Equation risk and CKD awareness were assessed using multivariable logistic regression. CKD awareness was compared with awareness of hypertension and diabetes during the same period. RESULTS: In 2011 to 2016, unadjusted CKD awareness was 9.6%, 22.6%, 44.7%, and 49.0% in the minimal-, low-, intermediate-, and high-risk groups, respectively. In adjusted analyses, these proportions did not change over time. Awareness of CKD, including among the highest risk group, remains consistently below that of hypertension and diabetes and awareness of these conditions increased over time. LIMITATIONS: Imperfect sensitivity of the "weak or failing kidneys" question for ascertaining CKD awareness. CONCLUSIONS: Among adults with CKD G3-G4 who have 5-year estimated risks for kidney failure of 5%-<15% and≥15%, approximately half were unaware of their kidney disease, a gap that has persisted nearly 2 decades.

Elevated serum anion gap in adults with moderate chronic kidney disease increases risk for progression to end-stage renal disease.

Acid retention associated with reduced glomerular filtration rate (GFR) exacerbates nephropathy progression in partial nephrectomy models of chronic kidney disease (CKD) and might be reflected in patients with CKD with reduced estimated GFR (eGFR) by increased anion gap (AG). We explored the presence of AG and its association with CKD in 14,924 adults aged ≥20 yr with eGFR ≥ 15 ml·min-1·1.73 m-2 enrolled in the National Health and Nutrition Examination Survey III, 1988-1994, using multivariable regression analysis. The model was adjusted for sociodemographic characteristics, diabetes, and hypertension. We further examined the association between AG and incident end-stage renal disease (ESRD) using frailty models, adjusting for demographics, clinical factors, body mass index, serum albumin, bicarbonate, eGFR, and urinary albumin-to-creatinine ratio by following 558 adults with moderate CKD for 12 yr via the United States Renal Data System. Laboratory measures determined AG using the traditional, albumin-corrected, and full AG definitions. Individuals with moderate CKD (eGFR: 30-59 ml·min-1·1.73 m-2) had a greater AG than those with eGFR ≥ 60 ml·min-1·1.73 m-2 in multivariable regression analysis with adjustment for covariates. We found a graded relationship between the adjusted mean for all three definitions of AG and eGFR categories (P trend < 0.0001). During followup, 9.2% of adults with moderate CKD developed ESRD. Those with AG in the highest tertile had a higher risk of ESRD after adjusting for covariates in a frailty model [relative hazard (95% confidence interval) for traditional AG: 1.76 (1.16-2.32)] compared with those in the middle tertile. The data suggest that high AG, even after adjusting for serum bicarbonate, is a contributing acid-base mechanism to CKD progression in adults with moderate chronic kidney disease.

Poor accordance to a DASH dietary pattern is associated with higher risk of ESRD among adults with moderate chronic kidney disease and hypertension.

The Dietary Approaches to Stop Hypertension (DASH) diet lowers blood pressure, an important risk factor for chronic kidney disease (CKD) and end-stage renal disease (ESRD). However, it is unclear whether adherence to a DASH diet confers protection against future ESRD, especially among those with pre-existing CKD and hypertension. We examined whether a DASH diet is associated with lower risk of ESRD among 1,110 adults aged ≥ 20 years with hypertension and CKD (estimated glomerular filtration rate, eGFR 30-59 ml/min/1.73 m2) enrolled in the National Health and Nutrition Examination Survey (1988-1994). Baseline DASH diet accordance score was assessed using a 24-hour dietary recall questionnaire. ESRD was ascertained by linkage to the U.S. Renal Data System registry. We used the Fine-Gray competing risks method to estimate the relative hazard (RH) for ESRD after adjusting for sociodemographics, clinical and nutritional factors, eGFR, and albuminuria. Over a median follow-up of 7.8 years, 18.4% of subjects developed ESRD. Compared to the highest quintile of DASH diet accordance, there was a greater risk of ESRD among subjects in quintiles 1 (RH=1.7; 95% CI 1.1-2.7) and 2 (RH 2.2; 95% CI 1.1-4.1). Significant interactions were observed with diabetes status and race/ethnicity, with the strongest association between DASH diet adherence and ESRD risk observed in individuals with diabetes and in non-Hispanic blacks. Low accordance to a DASH diet is associated with greater risk of ESRD in adults with moderate CKD and hypertension, particularly in non-Hispanic blacks and persons with diabetes.

Vascular Calcification Markers and Hemodialysis Vascular Access Complications.

BACKGROUND: Arteriovenous (AV) access dysfunction is a common complication in hemodialysis patients. Markers of vascular calcification are associated with cardiovascular outcomes and mortality in this population, but their association with vascular access outcomes is unknown. In this study, we aimed to evaluate the association between selected vascular calcification makers and vascular access complications in a cohort of hemodialysis patients. METHOD: Fetuin-A, osteopontin (OPN), osteoprotegerin (OPG), and bone morphogenetic protein-7 (BMP-7) were measured in blood samples from 219 dialysis patients in the Choice for Healthy Outcomes in Caring for end-stage renal disease study; these patients were using a permanent vascular access. Participants were followed for up to 1 year or until the occurrence of a vascular access intervention or replacement. Associations with AV fistula (AVF) and AV graft (AVG) intervention-free survival were assessed in models adjusted for demographic characteristics, comorbidities, and inflammation. RESULTS: A total of 24 out 103 participants with an AVF and 43 out of 116 participants with an AVG had an intervention during follow-up. Lower fetuin-A, higher OPN, and higher BMP-7 were associated with a higher risk of AVF intervention (adjusted hazard ratios [aHR] for highest versus lowest tertile = 0.30 [95% CI 0.10-0.94]) for fetuin-A, 3.84 (95% CI 1.16-12.74) for OPN, and 3.49 (95% CI 1.16-10.52) for BMP-7. OPG was not significantly associated with the risk of AVF intervention. The associations of OPN and BMP-7 with AVF intervention appeared stronger among participants without diabetes (aHR 8.06; 95% CI 1.11-58.57 for OPN and aHR 2.55; 95% CI 1.08-6.08 for BMP-7, respectively) than among their counterparts with diabetes (p interaction = 0.06). None of the markers studied were significantly associated with AVG interventions. CONCLUSION: Lower fetuin-A and higher OPN and BMP-7 are associated with complications in AVF but not in AVG, suggesting a role for calcification in the pathogenesis AVF failure.

Race/Ethnicity, Dietary Acid Load, and Risk of End-Stage Renal Disease among US Adults with Chronic Kidney Disease.

BACKGROUND: Dietary acid load (DAL) contributes to the risk of CKD and CKD progression. We sought to determine the relation of DAL to racial/ethnic differences in the risk of end-stage renal disease (ESRD) among persons with CKD. METHODS: Among 1,123 non-Hispanic black (NHB) and non-Hispanic white (NHW) National Health and Nutrition Examination Survey III participants with estimated glomerular filtration rate 15-59 mL/min/1.73 m2, DAL was estimated using the Remer and Manz net acid excretion (NAEes) formula and 24-h dietary recall. ESRD events were ascertained via linkage with Medicare. A competing risk model (accounting for death) was used to estimate the hazard ratio (HR) for treated ESRD, comparing NHBs with NHWs, adjusting for demographic, clinical and nutritional factors (body surface area, total caloric intake, serum bicarbonate, protein intake), and NAEes. Additionally, whether the relation of NAEes with ESRD risk varied by race/ethnicity was tested. RESULTS: At baseline, NHBs had greater NAEes (50.9 vs. 44.2 mEq/day) than NHWs. It was found that 22% developed ESRD over a median of 7.5 years. The unadjusted HR comparing NHBs to NHWs was 3.35 (95% CI 2.51-4.48) and adjusted HR (for factors above) was 1.68 (95% CI 1.18-2.38). A stronger association of NAE with risk of ESRD was observed among NHBs (adjusted HR per mEq/day increase in NAE 1.21, 95% CI 1.12-1.31) than that among NHWs (HR 1.08, 95% CI 0.96-1.20), p interaction for race/ethnicity × NAEes = 0.004. CONCLUSIONS: Among US adults with CKD, the association of DAL with progression to ESRD is stronger among NHBs than NHWs. DAL is worthy of further investigation for its contribution to kidney outcomes across race/ethnic groups.

Dietary Potential Renal Acid Load and Risk of Albuminuria and Reduced Kidney Function in the Jackson Heart Study.

OBJECTIVE: Diets high in sulfur-rich protein and low in fruit and vegetables affect human acid-base balance adversely and may have a harmful effect on progression of chronic kidney disease (CKD). Little is known about the relationship of participant characteristics, dietary acid load (DAL), and kidney injury in African-Americans with high risk of CKD progression. DESIGN AND METHODS: We examined the association of DAL with CKD in 3,257 African-Americans aged >20 years in Jackson Heart Study. DAL was measured with nutrient intakes assessed with a food frequency questionnaire, using a model described by Remer and Manz. We tested associations of participant characteristics with DAL using median regression, and associations of DAL with albuminuria (>17 mg/g for men, >25 mg/g for women), reduced kidney function (eGFR <60 mL/minute/1.73 m2), or CKD defined as albuminuria or reduced kidney function using logistic regression. We further explored whether endothelin and aldosterone production in participants with hypertension mediated risk of albuminuria or reduced kidney function due to the intake of an acid-inducing diet. RESULTS: Younger adults, men, and those with higher body mass index had higher DAL. Higher DAL, compared with lower, was associated with greater odds of reduced kidney function (OR [95% CI]: 2.82 [1.40-4.75]). Higher DAL was also associated with greater risk of CKD, and this persisted after adjustment for confounders. Results were similar in adults with hypertension; the OR [95% CI] for highest, versus lowest, tertile of DAL with albuminuria was 1.66 [1.01-2.59]. Aldosterone and endothelin mediated the association between DAL and albuminuria; the OR [95% CI] in the highest tertile was no longer significant 1.53 [0.97-2.40] after their inclusion. CONCLUSIONS: Higher DAL was associated with higher prevalence of CKD and with reduced kidney function. DAL may be an important target for future interventions in African-Americans at high risk of CKD.

Understanding Trends in Kidney Function 1 Year after Kidney Transplant in the United States.

Lower eGFR 1 year after kidney transplant is associated with shorter allograft and patient survival. We examined how practice changes in the past decade correlated with time trends in average eGFR at 1 year after kidney transplant in the United States in a cohort of 189,944 patients who received a kidney transplant between 2001 and 2013. We calculated the average eGFR at 1 year after transplant for the recipient cohort of each year using the appropriate Modification of Diet in Renal Disease equation depending on the prevailing methodology of creatinine measurement, and used linear regression to model the effects of practice changes on the national post-transplant eGFR trend. Between the 2001-2005 period and the 2011-2013 period, average 1-year post-transplant eGFR remained essentially unchanged, with differences of 1.34 (95% confidence interval, 1.03 to 1.65) ml/min per 1.73 m2 and 0.66 (95% confidence interval, 0.32 to 1.01) ml/min per 1.73 m2 among deceased and living donor kidney transplant recipients, respectively. Over time, the mean age of recipients increased and more marginal organs were used; adjusting for these trends unmasked a larger temporal improvement in post-transplant eGFR. However, changes in immunosuppression practice had a positive effect on average post-transplant eGFR and balanced out the negative effect of recipient/donor characteristics. In conclusion, average 1-year post-transplant eGFR remained stable, despite increasingly unfavorable attributes in recipients and donors. With an aging ESRD population and continued organ shortage, preservation of average post-transplant eGFR will require sustained improvement in immunosuppression and other aspects of post-transplant care.

Trimethylamine N-Oxide and Cardiovascular Events in Hemodialysis Patients.

Cardiovascular disease causes over 50% of the deaths in dialysis patients, and the risk of death is higher in white than in black patients. The underlying mechanisms for these findings are unknown. We determined the association of the proatherogenic metabolite trimethylamine N-oxide (TMAO) with cardiovascular outcomes in hemodialysis patients and assessed whether this association differs by race. We measured TMAO in stored serum samples obtained 3-6 months after randomization from a total of 1232 white and black patients of the Hemodialysis Study, and analyzed the association of TMAO with cardiovascular outcomes using Cox models adjusted for potential confounders (demographics, clinical characteristics, comorbidities, albumin, and residual kidney function). Mean age of the patients was 58 years; 35% of patients were white. TMAO concentration did not differ between whites and blacks. In whites, 2-fold higher TMAO associated with higher risk (hazard ratio [95% confidence interval]) of cardiac death (1.45 [1.24 to 1.69]), sudden cardiac death [1.70 (1.34 to 2.15)], first cardiovascular event (1.15 [1.01 to 1.32]), and any-cause death (1.22 [1.09 to 1.36]). In blacks, the association was nonlinear and significant only for cardiac death among patients with TMAO concentrations below the median (1.58 [1.03 to 2.44]). Compared with blacks in the same quintile, whites in the highest quintile for TMAO (≥135 µM) had a 4-fold higher risk of cardiac or sudden cardiac death and a 2-fold higher risk of any-cause death. We conclude that TMAO concentration associates with cardiovascular events in hemodialysis patients but the effects differ by race.

Results of the HEMO Study suggest that p-cresol sulfate and indoxyl sulfate are not associated with cardiovascular outcomes.

Cardiovascular disease, the leading cause of mortality in hemodialysis patients, is not fully explained by traditional risk factors. To help define non-traditional risk factors, we determined the association of predialysis total p-cresol sulfate, indoxyl sulfate, phenylacetylglutamine, and hippurate with cardiac death, sudden cardiac death, and first cardiovascular event in the 1,273 participants of the HEMO Study. The results were adjusted for potential demographic, clinical, and laboratory confounders. The mean age of the patients was 58 years, 63% were Black and 42% were male. Overall, there was no association between the solutes and outcomes. However, in sub-group analyses, among patients with lower serum albumin (under 3.6 g/dl), a twofold higher p-cresol sulfate was significantly associated with a 12% higher risk of cardiac death (hazard ratio 1.12; 95% confidence interval, 0.98-1.27) and 22% higher risk of sudden cardiac death (1.22, 1.06-1.41). Similar trends were also noted with indoxyl sulfate. Trial interventions did not modify the association between these solutes and outcomes. Routine clinical and lab data explained less than 22% of the variability in solute levels. Thus, in prevalent hemodialysis patients participating in a large U.S. hemodialysis trial, uremic solutes p-cresol sulfate, indoxyl sulfate, hippurate, and phenylacetylglutamine were not associated with cardiovascular outcomes. However, there were trends of toxicity among patients with lower serum albumin.

Food Insecurity, CKD, and Subsequent ESRD in US Adults.

BACKGROUND: Poor access to food among low-income adults has been recognized as a risk factor for chronic kidney disease (CKD), but there are no data for the impact of food insecurity on progression to end-stage renal disease (ESRD). We hypothesized that food insecurity would be independently associated with risk for ESRD among persons with and without earlier stages of CKD. STUDY DESIGN: Longitudinal cohort study. SETTING & PARTICIPANTS: 2,320 adults (aged ≥ 20 years) with CKD and 10,448 adults with no CKD enrolled in NHANES III (1988-1994) with household income ≤ 400% of the federal poverty level linked to the Medicare ESRD Registry for a median follow-up of 12 years. PREDICTOR: Food insecurity, defined as an affirmative response to the food-insecurity screening question. OUTCOME: Development of ESRD. MEASUREMENTS: Demographics, income, diabetes, hypertension, estimated glomerular filtration rate, and albuminuria. Dietary acid load was estimated from 24-hour dietary recall. We used a Fine-Gray competing-risk model to estimate the relative hazard (RH) for ESRD associated with food insecurity after adjusting for covariates. RESULTS: 4.5% of adults with CKD were food insecure. Food-insecure individuals were more likely to be younger and have diabetes (29.9%), hypertension (73.9%), or albuminuria (90.4%) as compared with their counterparts (P<0.05). Median dietary acid load in the food-secure versus food-insecure group was 51.2 mEq/d versus 55.6 mEq/d, respectively (P=0.05). Food-insecure adults were more likely to develop ESRD (RH, 1.38; 95% CI, 1.08-3.10) compared with food-secure adults after adjustment for demographics, income, diabetes, hypertension, estimated glomerular filtration rate, and albuminuria. In the non-CKD group, 5.7% were food insecure. We did not find a significant association between food insecurity and ESRD (RH, 0.77; 95% CI, 0.40-1.49). LIMITATIONS: Use of single 24-hour diet recall; lack of laboratory follow-up data and measure of changes in food insecurity over time; follow-up of cohort ended 10 years ago. CONCLUSIONS: Among adults with CKD, food insecurity was independently associated with a higher likelihood of developing ESRD. Innovative approaches to address food insecurity should be tested for their impact on CKD outcomes.

Serum Asymmetric and Symmetric Dimethylarginine and Morbidity and Mortality in Hemodialysis Patients.

BACKGROUND: Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) are putative uremic toxins that may exert toxicity by a number of mechanisms, including impaired nitric oxide synthesis and generation of reactive oxygen species. The study goal was to determine the association between these metabolites and cardiovascular outcomes in hemodialysis patients. STUDY DESIGN: Post hoc analysis of the Hemodialysis (HEMO) Study. SETTING & PARTICIPANTS: 1,276 prevalent hemodialysis patients with available samples 3 to 6 months after randomization. PREDICTOR: ADMA and SDMA measured in stored specimens. OUTCOMES: Cardiac death, sudden cardiac death, first cardiovascular event, and any-cause death. Association with predictors analyzed using Cox regression adjusted for potential confounders (including demographics, clinical characteristics, comorbid conditions, albumin level, and residual kidney function). RESULTS: Mean age of patients was 57±14 (SD) years, 63% were black, and 57% were women. Mean ADMA (0.9±0.2µmol/L) and SDMA levels (4.3±1.4µmol/L) were moderately correlated (r=0.418). Higher dialysis dose or longer session length were not associated with lower predialysis ADMA or SDMA concentrations. In fully adjusted models, each doubling of ADMA level was associated with higher risk (HR per 2-fold higher concentration; 95% CI) of cardiac death (1.83; 1.29-2.58), sudden cardiac death (1.79; 1.19-2.69), first cardiovascular event (1.50; 1.20-1.87), and any-cause death (1.44; 1.13-1.83). Compared to the lowest ADMA quintile (<0.745 µmol/L), the highest ADMA quintile (≥1.07µmol/L) was associated with higher risk (HR; 95% CI) of cardiac death (2.10; 1.44-3.05), sudden cardiac death (2.06; 1.46-2.90), first cardiovascular event (1.75; 1.35-2.27), and any-cause death (1.56; 1.21-2.00). SDMA level was associated with higher risk for cardiac death (HR, 1.40; 95% CI, 1.03-1.92), but this was no longer statistically significant after adjusting for ADMA level (HR, 1.20; 95% CI, 0.86-1.68). LIMITATIONS: Single time-point measurement of ADMA and SDMA. CONCLUSIONS: ADMA and, to a lesser extent, SDMA levels are associated with cardiovascular outcomes in hemodialysis patients.

Trends in Prevalence of Chronic Kidney Disease in the United States.

Background: Trends in the prevalence of chronic kidney disease (CKD) are important for health care policy and planning. Objective: To update trends in CKD prevalence. Design: Repeated cross-sectional study. Setting: NHANES (National Health and Nutrition Examination Survey) for 1988 to 1994 and every 2 years from 1999 to 2012. Participants: Adults aged 20 years or older. Measurements: Chronic kidney disease (stages 3 and 4) was defined as an estimated glomerular filtration rate (eGFR) of 15 to 59 mL/min/1.73 m2, estimated with the Chronic Kidney Disease Epidemiology Collaboration equation from calibrated serum creatinine measurements. An expanded definition of CKD also included persons with an eGFR of at least 60 mL/min/1.73 m2 and a 1-time urine albumin-creatinine ratio of at least 30 mg/g. Results: The unadjusted prevalence of stage 3 and 4 CKD increased from the late 1990s to the early 2000s. Since 2003 to 2004, however, the overall prevalence has largely stabilized (for example, 6.9% prevalence in 2003 to 2004 and in 2011 to 2012). There was little difference in adjusted prevalence of stage 3 and 4 CKD overall in 2003 to 2004 versus 2011 to 2012 after age, sex, race/ethnicity, and diabetes mellitus status were controlled for (P = 0.26). Lack of increase in CKD prevalence since the early 2000s was observed in most subgroups and with an expanded definition of CKD that included persons with higher eGFRs and albuminuria. Limitation: Serum creatinine and albuminuria were measured only once in each person. Conclusion: In a reversal of prior trends, there has been no appreciable increase in the prevalence of stage 3 and 4 CKD in the U.S. population overall during the most recent decade. Primary Funding Source: American Society of Nephrology Foundation for Kidney Research Student Scholar Grant Program, Centers for Disease Control and Prevention, and National Institutes of Health.

Kt/Vurea and Nonurea Small Solute Levels in the Hemodialysis Study.

The Hemodialysis (HEMO) Study showed that high-dose hemodialysis providing a single-pool Kt/Vurea of 1.71 provided no benefit over a standard treatment providing a single-pool Kt/Vurea of 1.32. Here, we assessed whether the high-dose treatment used lowered plasma levels of small uremic solutes other than urea. Measurements made ≥3 months after randomization in 1281 patients in the HEMO Study showed a range in the effect of high-dose treatment compared with that of standard treatment: from no reduction in the level of p-cresol sulfate or asymmetric dimethylarginine to significant reductions in the levels of trimethylamine oxide (-9%; 95% confidence interval [95% CI], -2% to -15%), indoxyl sulfate (-11%; 95% CI, -6% to -15%), and methylguanidine (-22%; 95% CI, -18% to -27%). Levels of three other small solutes also decreased slightly; the level of urea decreased 9%. All-cause mortality did not significantly relate to the level of any of the solutes measured. Modeling indicated that the intermittency of treatment along with the presence of nondialytic clearance and/or increased solute production accounted for the limited reduction in solute levels with the higher Kt/Vurea In conclusion, failure to achieve greater reductions in solute levels may explain the failure of high Kt/Vurea treatment to improve outcomes in the HEMO Study. Furthermore, levels of the nonurea solutes varied widely among patients in the HEMO Study, and achieved Kt/Vurea accounted for very little of this variation. These results further suggest that an index only on the basis of urea does not provide a sufficient measure of dialysis adequacy.