Circulating Metabolomic Associations with Neurocognitive Outcomes in Pediatric CKD.

BACKGROUND: Children with CKD are at risk for impaired neurocognitive functioning. We investigated metabolomic associations with neurocognition in children with CKD. METHODS: We leveraged data from the Chronic Kidney Disease in Children (CKiD) study and the Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease (NiCK) study. CKiD is a multi-institutional cohort that enrolled children aged 6 months to 16 years with eGFR 30-90 ml/min per 1.73 m 2 ( n =569). NiCK is a single-center cross-sectional study of participants aged 8-25 years with eGFR<90 ml/min per 1.73 m 2 ( n =60) and matched healthy controls ( n =67). Untargeted metabolomic quantification was performed on plasma (CKiD, 622 metabolites) and serum (NiCK, 825 metabolites) samples. Four neurocognitive domains were assessed: intelligence, attention regulation, working memory, and parent ratings of executive function. Repeat assessments were performed in CKiD at 2-year intervals. Linear regression and linear mixed-effects regression analyses adjusting for age, sex, delivery history, hypertension, proteinuria, CKD duration, and glomerular versus nonglomerular diagnosis were used to identify metabolites associated with neurocognitive z-scores. Analyses were performed with and without adjustment for eGFR. RESULTS: There were multiple metabolite associations with neurocognition observed in at least two of the analytic samples (CKiD baseline, CKiD follow-up, and NiCK CKD). Most of these metabolites were significantly elevated in children with CKD compared with healthy controls in NiCK. Notable signals included associations with parental ratings of executive function: phenylacetylglutamine, indoleacetylglutamine, and trimethylamine N-oxide-and with intelligence: γ -glutamyl amino acids and aconitate. CONCLUSIONS: Several metabolites were associated with neurocognitive dysfunction in pediatric CKD, implicating gut microbiome-derived substances, mitochondrial dysfunction, and altered energy metabolism, circulating toxins, and redox homeostasis.

Using Machine Learning to Identify Metabolomic Signatures of Pediatric Chronic Kidney Disease Etiology.

BACKGROUND: Untargeted plasma metabolomic profiling combined with machine learning (ML) may lead to discovery of metabolic profiles that inform our understanding of pediatric CKD causes. We sought to identify metabolomic signatures in pediatric CKD based on diagnosis: FSGS, obstructive uropathy (OU), aplasia/dysplasia/hypoplasia (A/D/H), and reflux nephropathy (RN). METHODS: Untargeted metabolomic quantification (GC-MS/LC-MS, Metabolon) was performed on plasma from 702 Chronic Kidney Disease in Children study participants (n: FSGS=63, OU=122, A/D/H=109, and RN=86). Lasso regression was used for feature selection, adjusting for clinical covariates. Four methods were then applied to stratify significance: logistic regression, support vector machine, random forest, and extreme gradient boosting. ML training was performed on 80% total cohort subsets and validated on 20% holdout subsets. Important features were selected based on being significant in at least two of the four modeling approaches. We additionally performed pathway enrichment analysis to identify metabolic subpathways associated with CKD cause. RESULTS: ML models were evaluated on holdout subsets with receiver-operator and precision-recall area-under-the-curve, F1 score, and Matthews correlation coefficient. ML models outperformed no-skill prediction. Metabolomic profiles were identified based on cause. FSGS was associated with the sphingomyelin-ceramide axis. FSGS was also associated with individual plasmalogen metabolites and the subpathway. OU was associated with gut microbiome-derived histidine metabolites. CONCLUSION: ML models identified metabolomic signatures based on CKD cause. Using ML techniques in conjunction with traditional biostatistics, we demonstrated that sphingomyelin-ceramide and plasmalogen dysmetabolism are associated with FSGS and that gut microbiome-derived histidine metabolites are associated with OU.

Food Insecurity Is Associated with Prediabetes Risk Among U.S. Adolescents, NHANES 2003-2014.

Objective: Food insecurity has been linked to adverse health consequences. We sought to determine if food insecurity was related to obesity and prediabetes risk in U.S. adolescents. We also investigated if Supplemental Nutrition Assistance Program (SNAP) utilization mitigated any observed risks. Materials and Methods: We used linear and logistic regression analysis of cross-sectional data from a nationally representative sample of U.S. adolescents aged 12-19 years participating in the National Health And Nutrition Examination Survey 2003-2014 who had an income:poverty ratio of <5.0 and had complete data regarding metabolic laboratory assessments, food security, and socioeconomic status (n = 2662). Results: Food insecurity was present in 18.40% (95% confidence interval (CI): 16.47-20.37) among U.S. adolescents meeting inclusion criteria. Food insecurity was associated with increased odds of elevated blood pressure (adjusted odds ratio [aOR] = 1.57, 95% CI: 1.11-2.22) and prediabetes (aOR = 1.94, 95% CI: 1.16-3.25). SNAP usage was associated with higher body mass index z-score (e.g., mean: 0.80 vs. 0.59, P = 0.02), increased insulin resistance, and increased prediabetes odds among food-secure adolescents relative to nonusage. Conclusions: Food insecurity is relatively prevalent among U.S. adolescents with an income:poverty ratio of <5.0. Food insecurity is related to laboratory abnormalities and corresponding adverse health outcomes among U.S. adolescents in this relatively large sample. SNAP usage was associated with adverse health observations among food-secure adolescents. Ongoing efforts are still needed toward food assistance as important public health efforts aimed at mitigating the adverse outcomes related to food insecurity.

Food insecurity is associated with prediabetes and dietary differences in U.S. adults aged 20-39.

Food insecurity has been linked with lifestyle and metabolic health differences in varying populations. We sought to assess how food insecurity may have been associated with prediabetes and dietary differences in a relatively young subset of U.S. adults. We examined data from the United States National Health and Nutrition Examination Survey (2003-2014) participants aged 20-39 with complete data regarding food insecurity and metabolic laboratory assessment. We also assessed macronutrient intake and Supplemental Nutrition Assistance Program (SNAP) usage. All logistic regression models controlled for age, sex, and household income. Among 3684 included participants, food insecurity had 19.12% (95% confidence interval [95%CI]: 16.16, 22.08) prevalence. Food-insecure participants had prediabetes/diabetes prevalence of 37.36% (95%CI: 30.47, 44.25) and higher odds of having prediabetes/diabetes (adjusted odds ratio [aOR] = 1.36, 95%CI: 1.00, 1.85). Food-insecure adults has significantly different macronutrient intake: higher carbohydrates (p = 0.02), less protein (p = 0.01), and less total fat (p = 0.04) consumption. Food-insecure adults who used SNAP (compared to food-insecure adults who did not use SNAP) had higher odds of having metabolic syndrome (ATP-III MetS) (aOR = 2.56, 95%CI: 1.27, 5.22). We found that food insecurity was relatively prevalent in this subset of younger U.S. adults. We showed that food-insecure participants had increased prevalence and odds of prediabetes. These associations were also correlated with dietary differences.

Association between kindergarten and first-grade food insecurity and weight status in U.S. children.

OBJECTIVE: The aim of this study was to determine if food insecurity is an independent risk factor for obesity in U.S. children. METHODS: We analyzed data from a nationally representative sample of children participating in the Early Childhood Longitudinal Study-Kindergarten Cohort 2011. Statistical analyses were performed to evaluate longitudinal associations between food security and body mass index (BMI) z-score. All regression models included race/ethnicity, household income, and parental education. Survey and anthropometric data was collected from teachers and parents of 8167 U.S. children entering kindergarten in fall 2010 with regular follow-up through third grade. Complete data regarding food security, socioeconomic assessment, and BMI z-score data were included for statistical analyses. All analyses were weighted to be nationally representative. RESULTS: Children with household food insecurity had increased obesity prevalence from kindergarten through grade 3; for example, at kindergarten, with food insecurity 16.4% (95% confidence interval [CI], 13.7-19) versus food secure 12.4% (95% CI, 11.3-13.6). Adjusted means analysis showed first-grade food insecurity was significantly correlated with increased BMI z-score in first through third grades; for example, at first grade, with food insecurity 0.6 (95% CI, 0.5-0.7) versus food secure 0.4 (95% CI, 0.4-0.5). Logistic regression showed first-grade food insecurity was correlated with increased risk for obesity in that grade (odds ratio 1.4; 95% CI, 1.1-2). CONCLUSION: Obesity is more prevalent among food-insecure children. First-grade food insecurity is an independent risk factor for longitudinal increases in BMI z-score. There are differences in the association between food insecurity and weight status between kindergarten and first grade.

Increases in IGF-1 After Anti-TNF-α Therapy Are Associated With Bone and Muscle Accrual in Pediatric Crohn Disease.

Context: Low levels of insulinlike growth factor 1 (IGF-1) in pediatric and adolescent Crohn disease (CD) likely contribute to bone and muscle deficits. Objective: Assess changes in IGF-1 levels and associations with bone and muscle accrual following initiation of anti-tumor necrosis factor α (TNF-α) therapy in pediatric and adolescent CD. Design and Participants: Participants (n = 75, age 5 to 21 years) with CD were enrolled in a prospective cohort study; 63 completed the 12-month visit. Main Outcome Measures: IGF-1 levels at baseline and 10 weeks, as well as dual-energy x-ray absorptiometry (DXA) and tibia peripheral quantitative computed tomography (pQCT) measures of bone and muscle at baseline and 12 months after initiation of anti-TNF-α therapy. Outcomes were expressed as sex-specific z scores. Results: IGF-1 z scores increased from a median (interquartile range) of -1.0 (-1.58 to -0.17) to -0.36 (-1.04 to 0.36) over 10 weeks (P < 0.001). Lesser disease severity and systemic inflammation, as well as greater estradiol z scores (in girls), was significantly associated with greater IGF-1 z scores over time. DXA whole-body bone mineral content, leg lean mass, and total hip and femoral neck bone mineral density (BMD) z scores were low at baseline (P < 0.0001 vs reference data) and increased significantly (P < 0.001) over 12 months. Greater increases in IGF-1 z scores over 10 weeks predicted improvement in DXA bone and muscle outcomes and pQCT trabecular BMD and cortical area. Adjustment for changes in muscle mass markedly attenuated the associations between IGF-1 levels and bone outcomes. Conclusions: Short-term improvements in IGF-1 z scores predicted recovery of bone and muscle outcomes following initiation of anti-TNF-α therapy in pediatric CD. These data suggest that disease effects on growth hormone metabolism contribute to musculoskeletal deficits in CD.

Serum Alanine Aminotransferase Trends and Their Relationship with Obesity and Metabolic Syndrome in United States Adolescents, 1999-2014.

INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD), characterized by hepatocyte dysfunction, fat accumulation, and fibrosis, is the most common cause of chronic liver disease in children. Elevated levels of serum alanine aminotransferase (ALT) are used clinically to identify potential liver dysfunction. Our goal was to assess for changes in the national prevalence of elevated ALT over time and potential relationship to trends in the metabolic syndrome (MetS) severity and elevated body mass index (BMI). MATERIALS AND METHODS: We studied 5411 non-Hispanic white, non-Hispanic black, and Hispanic adolescents aged 12-19 with complete MetS Z-score and ALT data from the National Health and Nutrition Examination Survey 1999-2014. Elevated ALT levels were defined by two different cutoffs: one for both sexes (30 U/L) and another that was sex specific (22 U/L girls; 25 U/L boys). MetS severity was assessed using a sex- and race-/ethnicity-specific MetS Z-score. RESULTS: We did not find a statistically significant linear increase in either mean ALT or the prevalence of elevated ALT differed over time. As expected, ALT levels were significantly correlated with BMI Z-score and MetS Z-score (P < 0.0001). Over time, BMI Z-scores increased and MetS severity Z-score decreased. CONCLUSION: Prevalence of elevated ALT did not exhibit a linear change between 1999 and 2014 in U.S. adolescents, potentially due to divergent trends regarding BMI and MetS severity. Continued vigilance in monitoring BMI and ALT levels is advised for the U.S. adolescent population. MetS Z-score could act as an additional tool to monitor risk of elevated ALT and subsequent development of NAFLD.

Correlation of metabolic syndrome severity with cardiovascular health markers in adolescents.

BACKGROUND AND OBJECTIVES: The presence of metabolic syndrome (MetS) in childhood is a significant risk factor for later cardiovascular disease (CVD). Recent data showed temporal decreases in a sex- and race/ethnicity-specific MetS severity z-score among U.S. adolescents. Our goal was to characterize the relationship of this MetS z-score with other CVD risk indicators and assess their temporal trends and lifestyle influences. METHODS: We analyzed 4837 participants aged 12-20years from the National Health and Nutrition Examination Survey by 2-year waves from 1999 to 2012. We used linear regression to compare MetS z-score and dietary factors with serum levels of low-density lipoprotein (LDL), apolipoprotein-B (ApoB), high-sensitivity C-reactive protein (hsCRP) and uric acid. RESULTS: MetS severity z-score was positively correlated with LDL, ApoB, hsCRP, and uric acid measurements (p<0.0001 for all). These correlations held true among individual racial/ethnic groups. LDL, ApoB, and hsCRP measurements decreased over time among U.S. adolescents (p=0.002, p<0.0001, and p=0.024, respectively). Saturated fat consumption was positively correlated with LDL (p=0.005) and ApoB (p=0.012) and inversely related to serum uric acid (p=0.001). Total caloric intake was inversely related to LDL (p=0.003) and serum uric acid (p=0.003). Unsaturated fat, carbohydrate, and protein consumption were not related to LDL, ApoB, hsCRP, or serum uric acid. CONCLUSIONS: There is a positive correlation between MetS severity and all four CVD risk indicators studied. LDL, ApoB, and hsCRP showed favorable temporal trends, which could be related to similar trends in MetS z-score. These data support the importance of considering multiple inter-related factors in clinical CVD risk assessment.

Examining trends in prediabetes and its relationship with the metabolic syndrome in US adolescents, 1999-2014.

AIMS: We sought to investigate temporal trends in prediabetes prevalence among US adolescents using two definitions and evaluate relationships with obesity and a MetS-severity score. METHODS: We evaluated data from 5418 non-Hispanic white, non-Hispanic black, and Hispanic adolescents aged 12-19 participating in the National Health and Nutrition Examination Survey 1999-2014 with complete data regarding MetS and hemoglobin A1c (HbA1c). Prediabetes status was defined by American Diabetes Association (ADA) criteria: fasting glucose 100-125 mg/dL or HbA1c 5.7%-6.4%. MetS severity was assessed with a MetS-severity Z-score. RESULTS: Prevalence of prediabetes as defined by HbA1c abnormalities significantly increased from 1999-2014, while prevalence of prediabetes as defined by fasting glucose abnormalities showed no significant temporal trend. There were variations in these trends across different racial/ethnic groups. MetS Z-score was overall more strongly correlated with HbA1c, fasting insulin, and the homeostasis model of insulin resistance than was BMI Z-score. These correlations were true in each racial/ethnic group with the exception that in non-Hispanic white adolescents, in whom the MetS Z-score was not significantly correlated with HbA1c measurements. CONCLUSION: We found conflicting findings of temporal trends of US adolescent prediabetes prevalence based on the ADA's prediabetes criteria. The increasing prevalence of prediabetes by HbA1c assessment is concerning and raises the urgency for increased awareness and appropriate measures of prediabetes status among physicians and patients.

Metabolic risk factors in nondiabetic adolescents with glomerular hyperfiltration.

BACKGROUND: In adults, glomerular hyperfiltration is associated with abnormalities related to metabolic syndrome (MetS). We investigated if glomerular hyperfiltration was associated with metabolic abnormalities in US adolescents without diabetes. METHODS: We analyzed data from the National Health and Nutrition Examination Survey, a nationally representative sample of US adolescents ages 12-17 years. Estimated glomerular filtration rate (eGFR) was determined using the bedside Schwartz equation; adolescents with hyperfiltration (eGFR >120 mL/min/1.73 m 2 ) were compared to those with normal eGFR (90-120 mL/min/1.73 m 2 ). We calculated mean levels of factors related to MetS, insulin resistance and diabetes risk, adjusting for age, race/ethnicity, sex, socioeconomic status, and BMI z -score. RESULTS: Overall, 11.8% of US adolescents had hyperfiltration [95% confidence interval (CI) 10.6-13.0]. Hyperfiltration prevalence varied by race (20.2% in Hispanics versus 9.8% non-Hispanic whites and 7.4% non-Hispanic blacks; P< 0.001). Compared to those with normal eGFR, adolescents with hyperfiltration had higher adjusted mean levels of triglyceride (83 versus 77 mg/dL; P = 0.05), fasting insulin (15.1 versus 12.9; P< 0.001) and homeostatic model assessment of insulin resistance (3.52 versus 3.01; P = 0.001). These differences persisted after adjusting for BMI z- score. Adolescents with hyperfiltration had increased odds for hypertriglyceridemia [odds ratio 1.58 (95% CI 1.11-2.23)]. These relationships varied by racial/ethnic group. CONCLUSIONS: Glomerular hyperfiltration is associated with hypertriglyceridemia and increased insulin resistance independent of BMI z- score in a nationally representative sample of US adolescents. Hispanic adolescents are more likely to have hyperfiltration than other racial/ethnic groups. These findings could have significance in evaluations of renal function and MetS in adolescents to identify related risks and target interventions.

Trends in Metabolic Syndrome Severity and Lifestyle Factors Among Adolescents.

BACKGROUND AND OBJECTIVES: Childhood metabolic syndrome (MetS) is a risk factor for adverse outcomes later in life. Our goal was to identify temporal trends among US adolescents in the severity of MetS, its individual components, and factors related to diet and physical activity. METHODS: We analyzed 5117 participants aged 12 to 19 from NHANES. We used regression analysis of individual waves of data, 1999 to 2012. MetS severity was calculated using a gender- and race/ethnicity-specific MetS severity z score. RESULTS: There was a linear trend of decreasing MetS severity in US adolescents from 1999 to 2012 (P = .030). This occurred despite a trend of increasing BMI z score (P = .005); instead, the decrease in MetS severity appeared to be due to trends in increasing high-density lipoprotein (HDL; P < .0001) and decreasing triglyceride (P = .0001) levels. In considering lifestyle factors, there was no change in physical activity over the time period. Regarding dietary patterns, total calorie consumption and carbohydrate consumption were positively associated with triglyceride levels and negatively associated with HDL levels, whereas unsaturated fat consumption exhibited the opposite associations. Consistent with these associations, there was a trend of decreasing total calorie consumption (P < .0001), decreasing carbohydrate consumption (P < .0001), and increasing unsaturated fat consumption (P = .002). CONCLUSIONS: The healthier trend of declining MetS severity in adolescents appeared to be due to favorable increases in HDL and decreases in fasting triglyceride measurements. These were in turn associated with favorable changes in dietary patterns among US adolescents. Future studies should investigate the causality of dietary differences on changes in MetS severity in adolescents.

What should the ideal HIV self-test look like? A usability study of test prototypes in unsupervised HIV self-testing in Kenya, Malawi, and South Africa.

HIV self-testing (HIVST) is increasingly being sought and offered globally, yet there is limited information about the test features that will be required for an HIV self-test to be easy to use, acceptable to users, and feasible for manufacturers to produce. We conducted formative usability research with participants who were naïve to HIVST using five prototypes in Kenya, Malawi, and South Africa. The tests selected ranged from early-stage prototypes to commercially ready products and had a diverse set of features. A total of 150 lay users were video-recorded conducting unsupervised self-testing and interviewed to understand their opinions of the test. Participants did not receive a test result, but interpreted standardized result panels. This study demonstrated that users will refer to the instructions included with the test, but these can be confusing or difficult to follow. Errors were common, with less than 25% of participants conducting all steps correctly and 47.3% of participants performing multiple errors, particularly in sample collection and transfer. Participants also had difficulty interpreting results. To overcome these issues, the ideal HIV self-test requires pictorial instructions that are easy to understand, simple sample collection with integrated test components, fewer steps, and results that are easy to interpret.

The efficiency of dentin sialoprotein-phosphophoryn processing is affected by mutations both flanking and distant from the cleavage site.

Normal dentin mineralization requires two highly acidic proteins, dentin sialoprotein (DSP) and phosphophoryn (PP). DSP and PP are synthesized as part of a single secreted precursor, DSP-PP, which is conserved in marsupial and placental mammals. Using a baculovirus expression system, we previously found that DSP-PP is accurately cleaved into DSP and PP after secretion into medium by an endogenous, secreted, zinc-dependent Sf9 cell activity. Here we report that mutation of conserved residues near and distant from the G(447)↓D(448) cleavage site in DSP-PP(240) had dramatic effects on cleavage efficiency by the endogenous Sf9 cell processing enzyme. We found that: 1) mutation of residues flanking the cleavage site from P(4) to P(4)' blocked, impaired, or enhanced DSP-PP(240) cleavage; 2) certain conserved amino acids distant from the cleavage site were important for precursor cleavage; 3) modification of the C terminus by appending a C-terminal tag altered the pattern of processing; and 4) mutations in DSP-PP(240) had similar effects on cleavage by recombinant human BMP1, a candidate physiological processing enzyme, as was seen with the endogenous Sf9 cell activity. An analysis of a partial TLR1 cDNA from Sf9 cells indicates that residues that line the substrate-binding cleft of Sf9 TLR1 and human BMP1 are nearly perfectly conserved, offering an explanation of why Sf9 cells so accurately process mammalian DSP-PP. The fact that several mutations in DSP-PP(240) significantly modified the amount of PP(240) product generated from DSP-PP(240) precursor protein cleavage suggests that such mutation may affect the mineralization process.