Association of Intermediate-Stage Age-Related Macular Degeneration with Plasma Inflammatory Biomarkers in Persons with AIDS

Purpose

To evaluate associations of plasma levels of inflammatory biomarkers with age-related macular degeneration (AMD) and cataract in persons with AIDS.

Design

Nested case-control study (analysis 1) and nested cohort study (analysis 2).

Participants

Analysis 1: persons with AIDS and incident intermediate-stage AMD (n = 26) and controls without AMD matched for age, race/ethnicity, and gender (n = 49) from The Longitudinal Study of Ocular Complications of AIDS. Analysis 2: 475 persons from LSOCA with baseline plasma biomarker levels followed prospectively for cataract.

Methods

In both analyses, cryopreserved plasma specimens obtained at baseline were assayed for monocyte chemoattractant protein (MCP)-1 (CC motif chemokine ligand [CCL] 2), macrophage inflammatory protein (MIP)-1β (CCL4), soluble tumor necrosis factor receptor (sTNFR) 2, interleukin (IL)-18, and fractalkine (CX3 motif chemokine ligand 1 [CX3CL1]).

Main Outcome Measures

Analysis 1: mean difference (cases - controls) in plasma biomarker levels. Analysis 2: incident cataract.

Results

After adjusting for plasma human immunodeficiency virus RNA level, CD4+ T-cell count, and smoking, elevated baseline plasma levels of sTNFR2 and IL-18 (mean differences [cases - controls] 0.11 log10[pg/mL]; 95% confidence interval [CI], 0.01-0.20; P = 0.024 and 0.13 log10[pg/mL]; 95% CI, 0.01-0.24; P = 0.037, respectively) each were associated with incident AMD. In a competing risk (with mortality) analysis, elevated baseline standardized log10 plasma levels of MCP-1, sTNFR2, IL-18, and fractalkine each were associated with a decreased cataract risk.

Conclusions

When combined with previous data suggesting that AMD is associated with elevated plasma levels of C-reactive protein, soluble CD14, and possibly IL-6, the association of elevated plasma levels of sTNFR2 and IL-18 with incident AMD, but not with incident cataract, suggests that innate immune system activation, and possibly NLRP3 inflammasome activation, may play a role in the pathogenesis of AMD in this population.

Financial Disclosures

The authors have no proprietary or commercial interest in any materials discussed in this article.

Metabolic and inflammatory perturbation of diabetes associated gut dysbiosis in people living with and without HIV infection

BACKGROUND

Gut dysbiosis has been linked with both HIV infection and diabetes, but its interplay with metabolic and inflammatory responses in diabetes, particularly in the context of HIV infection, remains unclear.

METHODS

We first conducted a cross-sectional association analysis to characterize the gut microbial, circulating metabolite, and immune/inflammatory protein features associated with diabetes in up to 493 women (~ 146 with prevalent diabetes with 69.9% HIV +) of the Women's Interagency HIV Study. Prospective analyses were then conducted to determine associations of identified metabolites with incident diabetes over 12 years of follow-up in 694 participants (391 women from WIHS and 303 men from the Multicenter AIDS Cohort Study; 166 incident cases were recorded) with and without HIV infection. Mediation analyses were conducted to explore whether gut bacteria-diabetes associations are explained by altered metabolites and proteins.

RESULTS

Seven gut bacterial genera were identified to be associated with diabetes (FDR-q <  0.1), with positive associations for Shigella, Escherichia, Megasphaera, and Lactobacillus, and inverse associations for Adlercreutzia, Ruminococcus, and Intestinibacter. Importantly, the associations of most species, especially Adlercreutzia and Ruminococcus, were largely independent of antidiabetic medications use. Meanwhile, 18 proteins and 76 metabolites, including 3 microbially derived metabolites (trimethylamine N-oxide, phenylacetylglutamine (PAGln), imidazolepropionic acid (IMP)), 50 lipids (e.g., diradylglycerols (DGs) and triradylglycerols (TGs)) and 23 non-lipid metabolites, were associated with diabetes (FDR-q <  0.1), with the majority showing positive associations and more than half of them (59/76) associated with incident diabetes. In mediation analyses, several proteins, especially interleukin-18 receptor 1 and osteoprotegerin, IMP and PAGln partially mediate the observed bacterial genera-diabetes associations, particularly for those of Adlercreutzia and Escherichia. Many diabetes-associated metabolites and proteins were altered in HIV, but no effect modification on their associations with diabetes was observed by HIV.

CONCLUSION

Among individuals with and without HIV, multiple gut bacterial genera, blood metabolites, and proinflammatory proteins were associated with diabetes. The observed mediated effects by metabolites and proteins in genera-diabetes associations highlighted the potential involvement of inflammatory and metabolic perturbations in the link between gut dysbiosis and diabetes in the context of HIV infection.

Association of Androgen Hormones, Sex Hormone-Binding Globulin, and the Menopausal Transition With Incident Diabetes Mellitus in Women With and Without HIV

BACKGROUND

HIV is associated with alterations in androgen hormone levels and sex hormone-binding globulin (SHBG) in women. Higher SHBG has been associated with a lower risk of diabetes in the general population, but the contribution of HIV, androgen hormones, SHBG, and menopausal phase to diabetes is unclear.

METHODS

From April 2003 through February 2020, 896 women with HIV (WWH) and 343 women without HIV (WWOH) from the Women's Interagency HIV Study with morning total testosterone, dehydroepiandrosterone sulfate (DHEAS), and SHBG levels were followed to assess for incident diabetes. Parametric regression models were used with age as the time scale and relative times (RT) as the measure of association of hormone level and menopausal phase with incident diabetes. Analyses incorporated time-dependent androgen hormone, SHBG levels, and menopausal phase and were adjusted for race/ethnicity, enrollment year, smoking status, BMI, hepatitis C virus status, and HIV-related factors.

RESULTS

In total, 128 (14%) WWH and 47 (14%) WWOH developed diabetes. In WWH, a doubling of SHBG and DHEAS were associated with a 7% (RT = 1.07 [95% CI: 0.82 to 1.40] and 15% (RT = 1.15 [95% CI: 0.95 to 1.39]) longer time to diabetes, respectively; in WWOH, a doubling of SHBG and DHEAS were associated with 84% (RT = 1.84 [95% CI: 0.89 to 3.82]) and 41% (RT= 1.41 [95% CI: 0.82 to 2.44]) longer times to diabetes. Total testosterone was not associated. In WWH, later menopausal phase was associated with shorter times to diabetes.

CONCLUSIONS

Despite alterations in androgen hormone and SHBG levels in HIV, regardless of HIV status, higher SHBG and DHEAS were associated with nonstatistically significant slower progression to diabetes. The menopausal transition may be a better hormonal indicator of diabetes risk in WWH.

Genetic factors associated with age-related macular degeneration modulating plasma inflammatory biomarker levels in patients with AIDS

INTRODUCTION

Patients with the acquired immunodeficiency syndrome (AIDS) have an increased prevalence and incidence of intermediate-stage age-related macular degeneration (AMD). Several elevated plasma inflammatory biomarkers are associated with increased incidence of intermediate-stage AMD in this population. We evaluated the association between AMD risk alleles and plasma inflammatory biomarker levels in persons with AIDS.

MATERIALS AND METHODS

Cryopreserved plasma specimens of 229 non-Hispanic White and 252 non-Hispanic blacks from the Longitudinal Study of the Ocular Complications of AIDS cohort were assayed for plasma levels of soluble tumor necrosis factor receptor (sTNFR) 2, interleukin (IL)-18, C × 3motif chemokine ligand 1 (CX3CL1), C-reactive protein (CRP), and soluble CD14 (sCD14). Genotyping included AMD-associated variants rs10801553 and rs800292 for complement factor H (CFH) rs9332739 and rs547154 for complement factor 2 (C2), rs2230199 for C3, rs2285714 for CFI, and rs3732379 and rs3732378 for C × 3motif chemokine receptor 1 (CX3CR1).

RESULTS

In Whites, AMD low-risk CX3CR1 variants (V249I and T280M) were associated with reduced plasma levels of IL-18. In Blacks, AMD low-risk C3 R102G and low-risk CX3CR1 T280M variants were associated with reduced CRP levels.

CONCLUSIONS

Genetic variants in AMD-associated immune genes may influence AMD-associated systemic plasma inflammatory biomarker levels in patients with AIDS.

Trajectories of Antiretroviral Therapy Adherence and Virologic Failure in Women With HIV in the United States

BACKGROUND

Women with HIV (WHIV) in the United States face many challenges with adherence to antiretroviral therapy (ART), and suboptimal adherence often leads to virologic failure. This study aimed to determine the association between ART adherence trajectories and the risk of virologic failure.

METHODS

We included WHIV (aged 18 years or older) enrolled in the Women's Interagency HIV Study in the United States from April 2014 to September 2019 who had at least 2 consecutive measurements of HIV RNA and ≥3 measurements of self-reported adherence. Group-based trajectory modeling was used to identify adherence trajectories. Cox proportional hazard ratios were used to measure the association.

MAIN OUTCOME MEASURE

Virologic failure was defined as HIV RNA ≥200 copies/mL at 2 consecutive visits.

RESULTS

We included 1437 WHIV (median age 49 years). Of all women, 173 (12.0%) experienced virologic failure. Four adherence trajectories were identified, namely "consistently high" (26.3%), "moderate increasing" (9.5%), "moderate decreasing" (30.6%), and "consistently low" (33.5%). Women in the consistently low adherence group consumed alcohol and experienced depression more than other groups. Compared with the "consistently high" trajectory, the risk of virologic failure was higher among women with "consistently low" [adjusted hazard ratio (aHR) 2.8; 95% confidence interval (CI): 1.6 to 4.9; P < 0.001] and "moderate decreasing" adherence trajectories (aHR 1.8; 95% CI: 1.0 to 3.2; P = 0.04), but it was similar to those with "moderate increasing" adherence trajectory (aHR 1.0; 95% CI: 0.4 to 2.5; P = 0.94).

CONCLUSIONS

Adherence to ART remains a challenge among WHIV. Multilevel behavioral interventions to address poor adherence, alcohol consumption, and depression are needed.

Dual trajectories of antiretroviral therapy adherence and polypharmacy in women with HIV in the United States

BACKGROUND

Polypharmacy, using five or more medications, may increase the risk of nonadherence to prescribed treatment. We aimed to identify the interrelationship between trajectories of adherence to antiretroviral therapy (ART) and polypharmacy.

METHODS

We included women with HIV (aged ≥ 18) enrolled in the Women's Interagency HIV Study in the United States from 2014 to 2019. We used group-based trajectory modeling (GBTM) to identify trajectories of adherence to ART and polypharmacy and the dual GBTM to identify the interrelationship between adherence and polypharmacy.

RESULTS

Overall, 1,538 were eligible (median age of 49 years). GBTM analysis revealed five latent trajectories of adherence with 42% of women grouped in the consistently moderate trajectory. GBTM identified four polypharmacy trajectories with 45% categorized in the consistently low group.

CONCLUSIONS

The joint model did not reveal any interrelationship between ART adherence and polypharmacy trajectories. Future research should consider examining the interrelationship between both variables using objective measures of adherence.

Longitudinal Relationship Between Anemia and Statural Growth Impairment in Children and Adolescents With Nonglomerular CKD: Findings From the Chronic Kidney Disease in Children (CKiD) Study

RATIONALE & OBJECTIVE

Anemia and statural growth impairment are both prevalent in children with nonglomerular chronic kidney disease (CKD) and are associated with poor quality of life and increased morbidity and mortality. However, to date no longitudinal studies have demonstrated a relationship between anemia and statural growth in this population.

STUDY DESIGN

The CKD in Children (CKiD) study is a multicenter prospective cohort study with over 15 years of follow-up observation.

SETTING & PARTICIPANTS

CKiD participants younger than 22 years with nonglomerular CKD who had not reached final adult height.

EXPOSURE

Age-, sex-, and race-specific hemoglobin z score.

OUTCOME

Age- and sex-specific height z score.

ANALYTICAL APPROACH

The relationship between hemoglobin and height was quantified using (1) multivariable repeated measures paired person-visit analysis, and (2) multivariable repeated measures linear mixed model analysis. Both models were adjusted for age, sex, body mass index, estimated glomerular filtration rate, acidosis, and medication use.

RESULTS

Overall, 67% of the 510 participants studied had declining hemoglobin z score trajectories over the follow-up period, which included 1,763 person-visits. Compared with average hemoglobin z scores of≥0, average hemoglobin z scores of less than -1.0 were independently associated with significant growth impairment at the subsequent study visit, with height z score decline ranging from 0.24 to 0.35. Importantly, in 50% of cases hemoglobin z scores of less than -1.0 corresponded to hemoglobin values higher than those used as cutoffs defining anemia in the KDIGO clinical practice guideline for anemia in CKD. When stratified by age, the magnitude of the association peaked in participants aged 9 years. In line with paired-visit analyses, our mixed model analysis demonstrated that in participants with baseline hemoglobin z score less than -1.0, a hemoglobin z score decline over the follow-up period was associated with a statistically significant concurrent decrease in height z score.

LIMITATIONS

Limited ability to infer causality.

CONCLUSIONS

Hemoglobin decline is associated with growth impairment over time in children with mild to moderate nonglomerular CKD, even before hemoglobin levels reach the cutoffs that are currently used to define anemia in this population.

Associations of body mass index (BMI) and BMI change with progression of chronic kidney disease in children

BACKGROUND

Obesity is prevalent among children with chronic kidney disease (CKD) and is associated with cardiovascular disease and reduced quality of life. Its relationship with pediatric CKD progression has not been described.

METHODS

We evaluated relationships between both body mass index (BMI) category (normal, overweight, obese) and BMI z-score (BMIz) change on CKD progression among participants of the Chronic Kidney Disease in Children study. Kaplan-Meier survival curves and multivariable parametric failure time models depict the association of baseline BMI category on time to kidney replacement therapy (KRT). Additionally, the annualized percentage change in estimated glomerular filtration rate (eGFR) was modeled against concurrent change in BMIz using multivariable linear regression with generalized estimating equations which allowed for quantification of the effect of BMIz change on annualized eGFR change.

RESULTS

Participants had median age of 10.9 years [IQR: 6.5, 14.6], median eGFR of 50 ml/1.73 m2 [IQR: 37, 64] and 63% were male. 160 (27%) of 600 children with non-glomerular and 77 (31%) of 247 children with glomerular CKD progressed to KRT over a median of 5 years [IQR: 2, 8]. Times to KRT were not significantly associated with baseline BMI category. Children with non-glomerular CKD who were obese experienced significant improvement in eGFR (+ 0.62%; 95% CI: + 0.17%, + 1.08%) for every 0.1 standard deviation concurrent decrease in BMI. In participants with glomerular CKD who were obese, BMIz change was not significantly associated with annualized eGFR change.

CONCLUSION

Obesity may represent a target of intervention to improve kidney function in children with non-glomerular CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Longitudinal changes in uric acid concentration and their relationship with chronic kidney disease progression in children and adolescents

BACKGROUND

Elevated serum uric acid concentration is a risk factor for CKD progression. Its change over time and association with CKD etiology and concomitant changes in estimated glomerular filtration rate (eGFR) in children and adolescents are unknown.

METHODS

Longitudinal study of 153 children/adolescents with glomerular (G) and 540 with non-glomerular (NG) etiology from the CKD in Children (CKiD) study. Baseline serum uric acid, change in uric acid and eGFR over time, CKD etiology, and comorbidities were monitored. Adjusted linear mixed-effects regression models quantified the relationship between within-person changes in uric acid and concurrent within-person changes in eGFR.

RESULTS

Participants with stable uric acid over follow-up had CKD progression which became worse for increased baseline uric acid (average annual percentage changes in eGFR were - 1.4%, - 7.7%, and - 14.7% in those with G CKD with baseline uric acid < 5.5 mg/dL, 5.5 - 7.5 mg/dL, and > 7.5 mg/dL, respectively; these changes were - 1.4%, - 4.1%, and - 8.6% in NG CKD). Each 1 mg/dL increase in uric acid over follow-up was independently associated with significant concomitant eGFR decreases of - 5.7% (95%CI - 8.4 to - 3.0%) (G) and - 5.1% (95%CI - 6.3 to - 4.0%) (NG) for those with baseline uric acid < 5.5 mg/dL and - 4.3% (95%CI - 6.8 to - 1.6%) (G) and - 3.3% (95%CI - 4.1 to - 2.6%) (NG) with baseline uric acid between 5.5 and 7.5 mg/dL.

CONCLUSIONS

Higher uric acid levels and increases in uric acid over time are risk factors for more severe progression of CKD in children and adolescents. A higher resolution version of the Graphical abstract is available as Supplementary information.

Dual Trajectories of Antiretroviral Therapy Adherence and Polypharmacy in Women with HIV in the United States

Background Polypharmacy, using five or more medications, may increase the risk of nonadherence to prescribed treatment. We aimed to identify the interrelationship between trajectories of adherence to antiretroviral therapy (ART) and polypharmacy. Methods We included women with HIV (aged ≥ 18) enrolled in the Women's Interagency HIV Study in the United States from 2014 to 2019. We used group-based trajectory modeling (GBTM) to identify trajectories of adherence to ART and polypharmacy and the dual GBTM to identify the interrelationship between adherence and polypharmacy. Results Overall, 1,538 were eligible (median age of 49 years). GBTM analysis revealed five latent trajectories of adherence with 42% of women grouped in the consistently moderate trajectory. GBTM identified four polypharmacy trajectories with 45% categorized in the consistently low group. Conclusions The joint model did not reveal any interrelationship between ART adherence and polypharmacy trajectories. Future research should consider examining the interrelationship between both variables using objective measures of adherence.

Association of elevated plasma inflammatory biomarker levels with age-related macular degeneration but not cataract in persons with AIDS

OBJECTIVE

To evaluate the relationship between plasma biomarkers of systemic inflammation and incident age-related macular degeneration (AMD) in persons with the AIDS.

DESIGN

Case-control study.

METHODS

Participants with incident intermediate-stage AMD (N = 26) in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) and controls (N = 60) without AMD. Cryopreserved baseline plasma specimens were assayed for biomarkers of inflammation, including high-sensitivity C-reactive protein (CRP), interleukin (IL)-6, interferon-γ inducible protein (IP)-10, soluble CD14 (sCD14), soluble CD163 (sCD163), and intestinal fatty acid-binding protein (I-FABP).

RESULTS

After adjustment for age, sex, and race/ethnicity, baseline mean ± standard deviation (SD) log10(mg/ml) plasma levels of CRP (0.52 ± 0.60 vs. 0.20 ± 0.43; P = 0.01) and mean ± SD log10(pg/ml) plasma levels of sCD14 (6.31 ± 0.11 vs. 6.23 ± 0.14; P = 0.008) were significantly higher among cases (incident AMD) than among controls (no AMD). There was a suggestion that mean ± SD baseline log10(pg/ml) plasma IL-6 levels (0.24 ± 0.33 vs. 0.11 ± 0.29; P = 0.10) might be higher among cases than controls. In a separate analysis of 548 participants in LSOCA, elevated baseline levels of plasma inflammatory biomarkers were associated with a greater risk of mortality but not with an increased risk of incident cataract.

CONCLUSION

These data suggest that systemic inflammatory biomarkers are associated with incident AMD but not incident cataract in persons with AIDS, and that systemic inflammation may play a role in the pathogenesis of AMD.

Longitudinal outcomes of body mass index in overweight and obese children with chronic kidney disease

BACKGROUND

Longitudinal changes in body mass index (BMI) among overweight and obese children with chronic kidney disease (CKD) are not well characterized. We studied longitudinal trajectories and correlates of these trajectories, as results may identify opportunities to optimize health outcomes.

METHODS

Longitudinal changes in age-sex-specific BMI z-scores over 1851 person-years of follow-up were assessed in 524 participants of the Chronic Kidney Disease in Children Study. A total of 353 participants were categorized as normal (BMI > 5th to < 85th percentile), 56 overweight (BMI ≥ 85th to 95th percentile) and 115 obese (BMI ≥ 95th percentile) based on the average of three BMI measurements during the first year of follow-up. Studied covariates included age, sex, race, CKD etiology, corticosteroid usage, household income, and maternal education.

RESULTS

In unadjusted analysis, BMI z-scores decreased over time in elevated BMI groups (overweight: mean = - 0.06 standard deviations (SD) per year, 95% CI: - 0.11, - 0.01; obese: mean = - 0.04 SD per year, 95% CI: - 0.07, - 0.01). Among obese children, only age was associated with change in BMI z-score; children < 6 years had a mean decrease of 0.19 SD during follow-up (95% CI: - 0.30, - 0.09). Socioeconomic factors were not associated with change in BMI.

CONCLUSION

Overweight and obese children with CKD demonstrated a significant annual decline in BMI, though the absolute change was modest. Among obese children, only age < 6 years was associated with significant decline in BMI. Persistence of elevated BMI in older children and adolescents with CKD underscores the need for early prevention and effective intervention.

Expanding the Finnish Diabetes Risk Score for Predicting Diabetes Incidence in People Living with HIV

This study investigated whether the predictive ability of the Finnish Diabetes Risk Score (FINDRISC) can be improved among people with HIV by adding a marker of insulin resistance. In this longitudinal analysis of the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study, HIV-positive and HIV-negative participants without prevalent diabetes were included. FINDRISC score and the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) were calculated at baseline. Cox proportional hazards models were used to examine associations between baseline risk scores and time to incident diabetes (first self-report of diabetes medication use). Model discrimination (Uno's c-statistic) and calibration (observed vs. cumulative probability of diabetes) were assessed for FINDRISC, HOMA-IR, and combined FINDRISC and HOMA-IR. Overall, 2,527 men (1,299 HIV-positive and 1,228 HIV-negative, median age = 44) and 2,446 women (1,841 HIV-positive and 605 HIV-negative, median age = 41) were included. Over 47,040 person-years of follow-up, diabetes incidence rates per 1,000 person-years were 9.5 in HIV-positive men, 7.1 in HIV-negative men, 14.5 in HIV-positive women, and 15.1 in HIV-negative women. FINDRISC discrimination (HIV-positive men c = 0.64 [0.55, 0.74], HIV-negative men c = 0.74 [0.68, 0.79], HIV-positive women c = 0.68 [0.64, 0.71], and HIV-negative women c = 0.73 [0.66, 0.79]) was significantly better than that of HOMA-IR. FINDRISC was better calibrated than HOMA-IR in each of the four groups. Adding HOMA-IR did not improve FINDRISC discrimination/calibration. Diabetes risk prediction with FINDRISC was suboptimal in men and women with HIV, and its performance was not improved with addition of HOMA-IR. The optimal method for identifying people living with HIV at-risk for diabetes is yet to be identified.

Plasma Lipidomic Profiles and Risk of Diabetes: 2 Prospective Cohorts of HIV-Infected and HIV-Uninfected Individuals

OBJECTIVES

Antiretroviral therapy (ART) use is associated with disrupted lipid and glucose metabolism in people with HIV infection. We aimed to identify plasma lipid species associated with risk of diabetes in the context of HIV infection.

RESEARCH DESIGN AND METHODS

We profiled 211 plasma lipid species in 491 HIV-infected and 203 HIV-uninfected participants aged 35 to 55 years from the Women's Interagency HIV Study and the Multicenter AIDS Cohort Study. Cox proportional hazards model was used to examine associations between baseline lipid species and incident diabetes (166 diabetes cases were identified during a median follow-up of 12.6 years).

RESULTS

We identified 11 lipid species, representing independent signals for 8 lipid classes/subclasses, associated with risk of diabetes (P < 0.05 after FDR correction). After adjustment for multiple covariates, cholesteryl ester (CE) (22:4), lysophosphatidylcholine (LPC) (18:2), phosphatidylcholine (PC) (36:4), phosphatidylcholine plasmalogen (34:3), and phosphatidylethanolamine (PE) (38:2) were associated with decreased risk of diabetes (HRs = 0.70 to 0.82 per SD increment), while diacylglycerol (32:0), LPC (14:0), PC (38:3), PE (36:1), and triacylglycerol (50:1) were associated with increased risk of diabetes (HRs = 1.26 to 1.56 per SD increment). HIV serostatus did not modify any lipid-diabetes associations; however, most of these lipid species were positively associated with HIV and/or ART use, including 3 diabetes-decreased ( CE [22:4], LPC [18:2], PE [38:2]) and all 5 diabetes-increased lipid species.

CONCLUSIONS

This study identified multiple plasma lipid species associated with incident diabetes. Regardless of the directions of their associations with diabetes, most diabetes-associated lipid species were elevated in ART-treated people with HIV infection. This suggests a complex role of lipids in the link between ART and diabetes in HIV infection.

Adiposity, Sex, and Cardiovascular Disease Risk in Children With CKD: A Longitudinal Study of Youth Enrolled in the Chronic Kidney Disease in Children (CKiD) Study

RATIONALE & OBJECTIVE

Traditional and nontraditional cardiovascular disease risk factors are highly prevalent in children with chronic kidney disease (CKD). We examined the longitudinal association of adiposity with cardiac damage among children with CKD and explored whether this association was modified by sex.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Children with mild-to-moderate CKD enrolled in the Chronic Kidney Disease in Children (CKiD) Study at 49 pediatric nephrology centers across North America.

EXPOSURE

Age- and sex-specific body mass index (BMI) z score.

OUTCOME

Age- and sex-specific left ventricular mass index (LVMI) z score and left ventricular hypertrophy (LVH).

ANALYTICAL APPROACH

Longitudinal analyses using mixed-effects models to estimate sex-specific associations of BMI z scores with LVMI z score and with LVH, accounting for repeated measurements over time.

RESULTS

Among 725 children with 2,829 person-years of follow-up, median age was 11.0 years and median estimated glomerular filtration rate was 52.6mL/min/1.73m2. Nearly one-third of both boys and girls were overweight or obese, median LVMI z score was 0.18 (IQR: -0.67, 1.08), and 11% had LVH. Greater BMI z scores were independently associated with greater LVMI z scores and greater odds of LVH. For each 1-unit higher BMI z score, LVMI z score was 0.24 (95% CI, 0.17-0.31) higher in boys and 0.38 (95% CI, 0.29-0.47) higher in girls (Pinteraction = 0.01). For each 1-unit higher BMI z score, the odds of LVH was 1.5-fold (95% CI, 1.1-2.1) higher in boys and 3.1-fold (95% CI, 1.8-4.4) higher in girls (Pinteraction = 0.005).

LIMITATIONS

Not all children had repeated measurements. LVH is a surrogate and not a hard cardiac outcome. The observational design limits causal inference.

CONCLUSIONS

In children, adiposity is independently associated with the markers of cardiac damage, LVMI z score and LVH. This association is stronger among girls than boys. Pediatric overweight and obesity may therefore have a substantial impact on cardiovascular risk among children with CKD.

Grip strength in children with chronic kidney disease

BACKGROUND

The relationship between muscle strength and chronic kidney disease (CKD) in children is unknown. This study aims to quantify the association between grip strength (GS) and kidney function and to explore factors associated with grip strength in children and adolescents with CKD.

METHODS

We included 411 children (699 GS assessments) of the Chronic Kidney Disease in Children (CKiD) study. They were matched by age, sex, and height to a healthy control from the National Health and Nutrition Examination Survey to quantify the relationship between GS and CKD. Linear mixed models were used to identify factors associated with GS among CKD patients.

RESULTS

Median GS z-score was - 0.72 (IQR - 1.39, 0.11) among CKD patients with CKD stages 2 through 5 having significantly lower GS than CKD stage 1. Compared with healthy controls, CKiD participants had a decreased GS z-score (- 0.53 SD lower, 95% CI - 0.67 to - 0.39) independent of race/ethnicity and body mass index. Factors associated with reduced GS included longer duration of CKD, pre-pubertal status, delayed puberty, neuropsychiatric comorbidities, need of feeding support, need for alkali therapy, and hemoglobin level. Decreased GS was also associated with both a lower frequency and intensity of physical activity.

CONCLUSIONS

CKD is associated with impaired muscle strength in children independent of growth retardation and BMI. Exposure to CKD for a prolonged time is associated with impaired muscle strength. Potential mediators of the impact of CKD on muscle strength include growth retardation, acidosis, poor nutritional status, and low physical activity. Additional studies are needed to assess the efficacy of interventions targeted at these risk factors.

Combination of pediatric and adult formulas yield valid glomerular filtration rate estimates in young adults with a history of pediatric chronic kidney disease

As patients with chronic kidney disease (CKD) transition from pediatric nephrology care to adult care, their kidney function is clinically assessed by estimated glomerular filtration rate (eGFR) using both pediatric and adult equations, which may not be congruent. Here we evaluated commonly used eGFR equations and directly measured iohexol GFR (iGFR) among participants between ages 18 and 26 with a diagnosis of pediatric CKD in the Chronic Kidney Disease in Children (CKiD) cohort. The bedside serum creatinine (SCr)-only equation (CKiDSCr), the SCr-only CKD-EPI (CKD-EPISCr), the cystatin C (Cys)-only CKD-EPI (CKD-EPICys) and the combined SCr and Cys CKD-EPI (CKD-EPISCr-Cys) were compared with a) 279 measured iGFRs obtained from 187 participants and b) 548 eGFRs from the SCr and Cys-based CKiD equation (CKiDSCr-Cys) obtained from 219 participants. Among emerging adults with a median iGFR of 49 ml/min/1.73m2, the CKiDSCr-Cys equation had low bias (+1.5 ml/min/1.73m2) and high correlation (0.94), while CKiDSCr underestimated iGFR and CKiDSCr-Cys (-5.6 and -7.4 ml/min/1.73m2, respectively) and CKD-EPISCr had an overestimation bias (+8.2 and +6.1 ml/min/1.73m2, respectively). However, the CKD-EPICys and CKD-EPISCr-Cys exhibited strong agreement with both iGFR and CKiDSCr-Cys. GFR may also be validly estimated in this population by taking the simple average of CKiDSCr and CKD-EPISCr (average bias +1.3 compared to iGFR and -0.6 compared to CKiDSCr-Cys). Clinicians should be aware that individually the pediatric and adult SCr-based estimates of GFR had large discrepancies among emerging adults with pediatric CKD. Thus, when cystatin C is not available, we recommend the average of pediatric and adult SCr-based eGFR as a valid tool for clinical use.

Room for Improvement: The HIV-Diabetes Care Continuum Over 15 Years in the Women's Interagency HIV Study

Background

Gains in life expectancy through optimal control of HIV infection with antiretroviral therapy (ART) may be threatened if other comorbidities, such as diabetes, are not optimally managed.

Methods

We analyzed cross-sectional data of the Women's Interagency HIV Study (WIHS) from 2001, 2006, and 2015. We estimated the proportions of HIV-positive and HIV-negative women with diabetes who were engaged in care and achieved treatment goals (hemoglobin A1c [A1c] <7.0%, blood pressure [BP] <140/90 mmHg, low-density lipoprotein [LDL] cholesterol <100 mg/dL, not smoking) and viral suppression. Repeated-measures models were used to estimate the adjusted prevalence of achieving each diabetes treatment goal at each time point, by HIV status.

Results

We included 486 HIV-positive and 258 HIV-negative women with diabetes. In 2001, 91.8% visited a health care provider, 60.7% achieved the A1c target, 70.5% achieved the BP target, 38.5% achieved the LDL cholesterol target, 49.2% were nonsmokers, 23.3% achieved combined ABC targets (A1c, BP, and cholesterol), and 10.9% met combined ABC targets and did not smoke. There were no differences by HIV status, and patterns were similar in 2006 and 2015. Among HIV-positive women, viral suppression increased from 41% in 2001 to 87% in 2015 compared with 8% and 13% achieving the ABC goals and not smoking. Viral suppression was not associated with achievement of diabetes care goals.

Conclusions

Successful management of HIV is outpacing that of diabetes. Future studies are needed to identify factors associated with gaps in the HIV-diabetes care continuum and design interventions to better integrate effective diabetes management into HIV care.

On the Physical Basis of Biological Signaling by Interface Pulses

Currently, biological signaling is envisaged as a combination of activation and movement, triggered by local molecular interactions and molecular diffusion, respectively. However, here, we suggest that other fundamental physical mechanisms might play an at least equally important role. We have recently shown that lipid interfaces permit the excitation and propagation of sound pulses. Here, we demonstrate that these reversible perturbations can control the activity of membrane-embedded enzymes without a requirement for molecular transport. They can thus facilitate rapid communication between distant biological entities at the speed of sound, which is here on the order of 1 m/s within the membrane. The mechanism described provides a new physical framework for biological signaling that is fundamentally different from the molecular approach that currently dominates the textbooks.

FGF23 and Left Ventricular Hypertrophy in Children with CKD

BACKGROUND AND OBJECTIVES

High plasma concentration of fibroblast growth factor 23 (FGF23) is a risk factor for left ventricular hypertrophy (LVH) in adults with CKD, and induces myocardial hypertrophy in experimental CKD. We hypothesized that high FGF23 levels associate with a higher prevalence of LVH in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed echocardiograms and measured plasma C-terminal FGF23 concentrations in 587 children with mild-to-moderate CKD enrolled in the Chronic Kidney Disease in Children (CKiD) study. We used linear and logistic regression to analyze the association of plasma FGF23 with left ventricular mass index (LVMI) and LVH (LVMI ≥95th percentile), adjusted for demographics, body mass index, eGFR, and CKD-specific factors. We also examined the relationship between FGF23 and LVH by eGFR level.

RESULTS

Median age was 12 years (interquartile range, 8-15) and eGFR was 50 ml/min per 1.73 m2 (interquartile range, 38-64). Overall prevalence of LVH was 11%. After adjustment for demographics and body mass index, the odds of having LVH was higher by 2.53 (95% confidence interval, 1.28 to 4.97; P<0.01) in participants with FGF23 concentrations ≥170 RU/ml compared with those with FGF23<100 RU/ml, but this association was attenuated after full adjustment. Among participants with eGFR≥45 ml/min per 1.73 m2, the prevalence of LVH was 5.4%, 11.2%, and 15.3% for those with FGF23 <100 RU/ml, 100-169 RU/ml, and ≥170 RU/ml, respectively (Ptrend=0.01). When eGFR was ≥45 ml/min per 1.73 m2, higher FGF23 concentrations were independently associated with LVH (fully adjusted odds ratio, 3.08 in the highest versus lowest FGF23 category; 95% confidence interval, 1.02 to 9.24; P<0.05; fully adjusted odds ratio, 2.02 per doubling of FGF23; 95% confidence interval, 1.29 to 3.17; P<0.01). By contrast, in participants with eGFR<45 ml/min per 1.73 m2, FGF23 did not associate with LVH.

CONCLUSIONS

Plasma FGF23 concentration ≥170 RU/ml is an independent predictor of LVH in children with eGFR≥45 ml/min per 1.73 m2.

Albuminuria, Proteinuria, and Renal Disease Progression in Children with CKD

BACKGROUND AND OBJECTIVES

The role of albuminuria as an indicator of progression has not been investigated in children with CKD in the absence of diabetes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Children were enrolled from 49 centers of the CKD in Children study between January of 2005 and March of 2014. Cross-sectional multivariable linear regression (n=647) was used to examine the relationship between urine protein-to-creatinine (UP/C [milligrams per milligram]) and albumin-to-creatinine (ACR [milligrams per gram]) with eGFR (milliliters per minute per 1.73 m2). Parametric time-to-event analysis (n=751) was used to assess the association of UP/C, ACR, and urine nonalbumin-to-creatinine (Unon-alb/cr [milligrams per gram]) on the time to the composite endpoint of initiation of RRT or 50% decline in eGFR.

RESULTS

The median follow-up time was 3.4 years and 202 individuals experienced the event. Participants with a UP/C≥0.2 mg/mg and ACR≥30 mg/g had a mean eGFR that was 16 ml/min per 1.73 m2 lower than those with a UP/C<0.2 mg/mg and ACR<30 mg/g. Individuals with ACR<30 mg/g, but a UP/C≥0.2 mg/mg, had a mean eGFR that was 9.3 ml/min per 1.73 m2 lower than those with a UP/C<0.2 mg/mg and ACR<30 mg/g. When categories of ACR and Unon-alb/cr were created on the basis of clinically meaningful cutoff values of UP/C with the same sample sizes for comparison, the relative times (RTs) to the composite end-point were almost identical when comparing the middle (RT=0.31 for UP/C [0.2-2.0 mg/mg], RT=0.38 for ACR [56-1333 mg/g], RT=0.31 for Unon-alb/cr [118-715 mg/g]) and the highest (RT=0.08 for UP/C [>2.0 mg/mg], RT=0.09 for ACR [>1333 mg/g], RT=0.07 for Unon-alb/cr [>715 mg/g]) levels to the lowest levels. A similar trend was seen when categories were created on the basis of clinically meaningful cutoff values of ACR (<30, 30-300, >300 mg/g).

CONCLUSIONS

In children with CKD without diabetes, the utility of an initial UP/C, ACR, and Unon-alb/cr for characterizing progression is similar.

Cystatin C and Cardiac Measures in Children and Adolescents With CKD

BACKGROUND

Cardiovascular disease (CVD) is highly prevalent among children with chronic kidney disease (CKD). Cystatin C is an established marker of kidney function and an emerging biomarker for CVD events. We quantified the relationship between cystatin C level and cardiac structure and function over time among children with CKD and assessed whether cystatin C level and diastolic function retained an association after accounting for kidney function.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

678 children and adolescents with mild to moderate CKD enrolled in the CKD in Children (CKiD) Study with 1,228 echocardiographically obtained cardiac structure and function measurements.

PREDICTOR

Serum cystatin C (mg/L) measured annually.

OUTCOMES

Cardiac structure (left ventricular mass index [g/m^2.7]) and cardiac function (shortening fraction; E/A, E'/A', E/E' ratios) measured every other year.

MEASUREMENTS

Demographics and anthropometrics, measured glomerular filtration rate (mGFR), heart rate, blood pressure, hemoglobin z score, serum albumin level, and calcium-phosphorus product.

RESULTS

Independent of time, each 1-mg/L increase in cystatin C level was independently associated with a concurrent 7.7% (95% CI, 5.3%-10.0%) increase in left ventricular mass index, a -4.7% (95% CI, -7.0% to -2.4%) change in E/A ratio, a -6.6% (95% CI, -9.0% to -4.2%) change in E'/A' ratio, and a 2.5% (95% CI, 0.3%-4.7%) increase in E/E' ratio. mGFR was also independently associated with E'/A' ratio. When cystatin C level and mGFR were included in the same model, cystatin C level remained independently associated with E'/A' ratio, whereas mGFR was not.

LIMITATIONS

24% of the cohort was missing data for outcomes of interest or measurements; study population includes only children and adolescents with mild to moderate CKD.

CONCLUSIONS

In this study of children and adolescents with mild to moderate CKD, cystatin C level was independently associated with cardiac structure and diastolic function. Cystatin C level remained able to predict diastolic function decline via E'/A' ratio even after adjusting for mGFR, suggesting that cystatin C level may have an independent role in CVD risk stratification among children and adolescents with CKD.

Perceived appetite and clinical outcomes in children with chronic kidney disease

BACKGROUND

Children with chronic kidney disease (CKD) may have impaired caloric intake through a variety of mechanisms, with decreased appetite as a putative contributor. In adult CKD, decreased appetite has been associated with poor clinical outcomes. There is limited information about this relationship in pediatric CKD.

METHODS

A total of 879 participants of the Chronic Kidney Disease in Children (CKiD) study were studied. Self-reported appetite was assessed annually and categorized as very good, good, fair, or poor/very poor. The relationship between appetite and iohexol or estimated glomerular filtration rate (ieGFR), annual changes in anthropometrics z-scores, hospitalizations, emergency room visits, and quality of life were assessed.

RESULTS

An ieGFR < 30 ml/min per 1.73 m(2) was associated with a 4.46 greater odds (95 % confidence interval: 2.80, 7.09) of having a worse appetite than those with ieGFR >90. Appetite did not predict changes in height, weight, or BMI z-scores. Patients not reporting a very good appetite had more hospitalizations over the next year than those with a very good appetite. Worse appetite was significantly associated with lower parental and patient reported quality of life.

CONCLUSIONS

Self-reported appetite in children with CKD worsens with lower ieGFR and is correlated with clinical outcomes, including hospitalizations and quality of life.

Hyperuricemia and Progression of CKD in Children and Adolescents: The Chronic Kidney Disease in Children (CKiD) Cohort Study

BACKGROUND

Hyperuricemia is associated with essential hypertension in children. No previous studies have evaluated the effect of hyperuricemia on progression of chronic kidney disease (CKD) in children.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

Children and adolescents (n=678 cross-sectional; n=627 longitudinal) with a median age of 12.3 (IQR, 8.6-15.6) years enrolled at 52 North American sites of the CKiD (CKD in Children) Study.

PREDICTOR

Serum uric acid level (<5.5, 5.5-7.5, and >7.5mg/dL).

OUTCOMES

Composite end point of either >30% decline in glomerular filtration rate (GFR) or initiation of renal replacement therapy.

MEASUREMENTS

Age, sex, race, blood pressure status, GFR, CKD cause, urine protein-creatinine ratio (<0.5, 0.5-<2.0, and ≥2.0mg/mg), age- and sex-specific body mass index > 95th percentile, use of diuretics, and serum uric acid level.

RESULTS

Older age, male sex, lower GFR, and body mass index > 95th percentile were associated with higher uric acid levels. 162, 294, and 171 participants had initial uric acid levels < 5.5, 5.5 to 7.5, or >7.5 mg/dL, respectively. We observed 225 instances of the composite end point over 5 years. In a multivariable parametric time-to-event analysis, compared with participants with initial uric acid levels < 5.5mg/dL, those with uric acid levels of 5.5 to 7.5 or >7.5mg/dL had 17% shorter (relative time, 0.83; 95% CI, 0.62-1.11) or 38% shorter (relative time, 0.62; 95% CI, 0.45-0.85) times to event, respectively. Hypertension, lower GFR, glomerular CKD cause, and elevated urine protein-creatinine ratio were also associated with faster times to the composite end point.

LIMITATIONS

The study lacked sufficient data to examine how use of specific medications might influence serum uric acid levels and CKD progression.

CONCLUSIONS

Hyperuricemia is a previously undescribed independent risk factor for faster progression of CKD in children and adolescents. It is possible that treatment of children and adolescents with CKD with urate-lowering therapy could slow disease progression.

Medication adherence and growth in children with CKD

BACKGROUND AND OBJECTIVES

Poor growth is a consequence of CKD, but can often be partially or fully prevented or corrected with the use of a number of medications. The extent of nonadherence with medications used to treat or mitigate growth failure in CKD has not been examined prospectively in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The prevalence of both prescription of and nonadherence to recombinant human growth hormone (rhGH), phosphate binders, alkali, active vitamin D, nutritional vitamin D, iron, and erythrocyte-stimulating agents was summarized over the first seven visits of the Chronic Kidney Disease in Children cohort study. The association between self-reported nonadherence to each medication group and the mean annual change in age- and sex-specific height z score was quantified using seven separate linear regression models with generalized estimating equations.

RESULTS

Of 834 participants, 597 reported use of at least one of these medication groups and had adherence data available. Nonadherence ranged from 4% over all visits for erythrocyte-stimulating agents to 22% over all visits for nutritional vitamin D. Of the study participants, 451 contributed data to at least one of the analyses of adherence and changes in height z score. Children nonadherent to rhGH had no change in height z score, whereas those adherent to rhGH had a significant improvement of 0.16 SDs (95% confidence interval, 0.05 to 0.27); the effect size was slightly larger and remained significant after adjustment. Among participants with height≤3rd percentile and after adjustment, adherence to rhGH was associated with a 0.33 SD (95% confidence interval, 0.10 to 0.56) greater change in height z score. Nonadherence with other medication groups was not significantly associated with a change in height z score.

CONCLUSIONS

Self-reported nonadherence to rhGH was associated with poorer growth velocity in children with CKD, suggesting an opportunity for intervention and improved patient outcome.

Changes in Body Mass Index Following HAART Initiation among HIV-Infected Women in the Women's Interagency HIV Study

OBJECTIVE

Examine changes in, and factors associated with changing body mass index (BMI) in women following highly active antiretroviral therapy (HAART) initiation.

METHODS

1177 HIV-infected Women's Interagency HIV Study participants who contributed 10,754 years of follow-up following HAART initiation were studied. Changes in median BMI up to 15 years following HAART initiation, and the highest and lowest BMI reached following HAART initiation were summarized by pre-HAART BMI category (<18.5 [underweight], 18.5-<25.0 [normal weight], 25.0-<30.0 [overweight], 30.0-<40.0 [obese], and ≥ 40.0 [morbidly obese]). Multivariate mixed effects ordinal logistic regression estimated the degree of association of each exposure of interest with post-HAART BMI.

RESULTS

Before HAART, 39% percent of women had normal BMI, 31% were overweight, 23% were obese, and 5% were morbidly obese. Following HAART initiation, median BMI change (per 5 years) was 0.21 kg/m² (90% confidence interval [CI]: -1.33, 0.42) for those with normal pre-HAART BMI, 0.39 kg/m² (90% CI: 0.15,0.66) for overweight, 0.31 kg/m² (90% CI: -1.18,0.67) for obese, and -0.36kg/m² for morbidly obese women. After initiating HAART, 40% with normal pre-HAART BMI became overweight at some point; of those overweight, 46% remained overweight and 47% became obese; 71% of obese women remained obese and 27% became morbidly obese. Each year of nucleoside analog reverse transcriptase inhibitor use was associated with a 3% decreased odds of reaching a higher BMI category (OR 0.97, 95% CI: 0.95, 0.99), while each year of protease inhibitor or non-nucleoside analog reverse transcriptase inhibitor use were associated with a 6% (OR 1.06, 95% CI: 1.04, 1.08) and 5%(OR 1.05, 95% CI: 1.01, 1.08) increased odds of having a higher BMI category, respectively.

CONCLUSIONS

Although overweight and obesity are highly prevalent in this large cohort of HIV-infected, minority women, HAART use was associated with only a modest increase in BMI over time.

Reduced abuse, therapeutic errors, and diversion following reformulation of extended-release oxycodone in 2010

This study evaluated changes in abuse exposures, therapeutic error exposures, and diversion into illegal markets associated with brand extended-release oxycodone (ERO) following introduction of reformulated ERO. Original ERO and reformulated ERO street prices also were compared. Data from the Poison Center and Drug Diversion programs of the Researched Abuse, Diversion and Addiction-Related Surveillance (RADARS) System were used. Quarterly rates 2 years prior to introduction of reformulated ERO (October 2008 through September 2010) were compared to quarterly rates after introduction (October 2010 through March 2012) using negative binomial regression. Street prices were compared using a mixed effects linear regression model. Following reformulated ERO introduction, poison center ERO abuse exposures declined 38% (95% confidence interval [CI]: 31-45) per population and 32% (95% CI: 24-39) per unique recipients of dispensed drug. Therapeutic error exposures declined 24% (95% CI: 15-31) per population and 15% (95% CI: 6-24) per unique recipients of dispensed drug. Diversion reports declined 53% (95% CI: 41-63) per population and 50% (95% CI: 39-59) per unique recipients of dispensed drug. Declines exceeded those observed for other prescription opioids in aggregate. After its introduction, the street price of reformulated ERO was significantly lower than original ERO.

PERSPECTIVE

This article indicates that the abuse, therapeutic errors, and diversion of ERO declined following the introduction of a tamper-resistant reformulation of the product. Reformulating abused prescription opioids to include tamper-resistant properties may be an effective approach to reduce abuse of such products.

Circulating but not immobilized N-deglycosylated von Willebrand factor increases platelet adhesion under flow conditions

The role of von Willebrand factor (VWF) as a shear stress activated platelet adhesive has been related to a coiled-elongated shape conformation. The forces dominating this transition have been suggested to be controlled by the proteins polymeric architecture. However, the fact that 20% of VWF molecular weight originates from glycan moieties has so far been neglected in these calculations. In this study, we present a systematic experimental investigation on the role of N-glycosylation for VWF mediated platelet adhesion under flow. A microfluidic flow chamber with a stenotic compartment that allows one to mimic various physiological flow conditions was designed for the efficient analysis of the adhesion spectrum. Surprisingly, we found an increase in platelet adhesion with elevated shear rate, both qualitatively and quantitatively fully conserved when N-deglycosylated VWF (N-deg-VWF) instead of VWF was immobilized in the microfluidic channel. This has been demonstrated consistently over four orders of magnitude in shear rate. In contrast, when N-deg-VWF was added to the supernatant, an increase in adhesion rate by a factor of two was detected compared to the addition of wild-type VWF. It appears that once immobilized, the role of glycans is at least modified if not-as found here for the case of adhesion-negated. These findings strengthen the physical impact of the circulating polymer on shear dependent platelet adhesion events. At present, there is no theoretical explanation for an increase in platelet adhesion to VWF in the absence of its N-glycans. However, our data indicate that the effective solubility of the protein and hence its shape or conformation may be altered by the degree of glycosylation and is therefore a good candidate for modifying the forces required to uncoil this biopolymer.

Simultaneously propagating voltage and pressure pulses in lipid monolayers of pork brain and synthetic lipids

Hydrated interfaces are ubiquitous in biology and appear on all length scales from ions and individual molecules to membranes and cellular networks. In vivo, they comprise a high degree of self-organization and complex entanglement, which limits their experimental accessibility by smearing out the individual phenomenology. The Langmuir technique, however, allows the examination of defined interfaces, the controllable thermodynamic state of which enables one to explore the proper state diagrams. Here we demonstrate that voltage and pressure pulses simultaneously propagate along monolayers comprised of either native pork brain or synthetic lipids. The excitation of pulses is conducted by the application of small droplets of acetic acid and monitored subsequently employing time-resolved Wilhelmy plate and Kelvin probe measurements. The isothermal state diagrams of the monolayers for both lateral pressure and surface potential are experimentally recorded, enabling us to predict dynamic voltage pulse amplitudes of 0.1-3 mV based on the assumption of static mechanoelectrical coupling. We show that the underlying physics for such propagating pulses is the same for synthetic and natural extracted (pork brain) lipids and that the measured propagation velocities and pulse amplitudes depend on the compressibility of the interface. Given the ubiquitous presence of hydrated interfaces in biology, our experimental findings seem to support a fundamentally new mechanism for the propagation of signals and communication pathways in biology (signaling), which is based neither on protein-protein or receptor-ligand interaction nor diffusion.

Carotid intima-media thickness in children with CKD: results from the CKiD study

BACKGROUND AND OBJECTIVES

In adults, increased carotid intima-media thickness (cIMT) as assessed by ultrasonography is a valid predictor of cardiovascular events. Children with CKD are known to be at increased cardiovascular risk. This study sought to identify cardiovascular risk factors associated with increased cIMT in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a cross-sectional analysis of cIMT obtained after 12 months of follow-up of 101 children aged 2-18 years with mild to moderate CKD (median GFR 42.9 ml/min per 1.73 m(2)) in the Chronic Kidney Disease in Children cohort study enrolled between April 2005 and September 2009 and 97 healthy pediatric controls between January 2003 and December 2008. An average of six standardized B-mode ultrasound measurements constituted the overall cIMT measurement.

RESULTS

The median cIMT was 0.43 mm (interquartile range, 0.38-0.48) compared with 0.41 mm in healthy controls (P=0.03 for difference). After multivariable adjustment, the median cIMT was 0.02 mm (95% confidence interval [CI], 0.01-0.05) larger than that of the healthy controls. In a multivariable linear regression analysis, dyslipidemia and hypertension were associated with 0.05 mm (95% CI, 0.01-0.08) and 0.04 mm (95% CI, 0.003-0.08) greater mean cIMT, respectively. Body mass index, CKD etiology, GFR, birth weight, pubertal status, calcium, phosphorus, sex, and race were not associated with cIMT.

CONCLUSIONS

cIMT is significantly elevated among children with CKD, as is the prevalence of other cardiovascular risk factors. Of these risk factors, hypertension and dyslipidemia are significantly associated with increased cIMT.

Propagation of 2D pressure pulses in lipid monolayers and its possible implications for biology

The existence and propagation of acoustic pressure pulses on lipid monolayers at the air-water interface are directly observed by simple mechanical detection. The pulses are excited by small amounts of solvents added to the monolayer. Controlling the state of the lipid interface, we show that the pulses propagate at velocities c following the lateral compressibility κ. This is manifested by a pronounced minimum in c (∼0.3  m/s) within the transition regime. The role of interface density pulses in biology is discussed, in particular, in the context of communicating localized alterations in protein function (signaling) and nerve pulse propagation.

Prevalence and correlates of multiple cardiovascular risk factors in children with chronic kidney disease

BACKGROUND AND OBJECTIVES

Although prevalence of traditional cardiovascular risk factors (CVRF) has been described in children with CKD, the frequency with which these CVRF occur concomitantly and the clinical characteristics associated with multiple CVRF are unknown. This study determined the prevalence and characteristics of multiple CVRF in children in the Chronic Kidney Disease in Children study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using cross-sectional data from first follow-up visits, we determined the prevalence of four CVRF: hypertension (casual BP >95(th) percentile or self-reported hypertension with concurrent use of anti-hypertensive medication), dyslipidemia (triglycerides >130 mg/dl, HDL <40 mg/dl, non-HDL >160 mg/dl, or use of lipid-lowering medication), obesity (BMI >95(th) percentile), and abnormal glucose metabolism (fasting glucose >110 mg/dl, insulin >20 μIU/ml, or HOMA-IR >2.20, >3.61, or >3.64 for those at Tanner stage 1, 2 to 3, or 4 to 5, respectively) in 250 children (median age 12.2 years, 74% Caucasian, median iohexol-based GFR 45.2 ml/min per 1.73 m(2)).

RESULTS

Forty-six percent had hypertension, 44% had dyslipidemia, 15% were obese, and 21% had abnormal glucose metabolism. Thirty-nine percent, 22%, and 13% had one, two, and three or more CVRF, respectively. In multivariate ordinal logistic regression analysis, glomerular disease and nephrotic-range proteinuria were associated with 1.96 (95% confidence interval, 1.04 to 3.72) and 2.04 (95% confidence interval, 0.94 to 4.43) higher odds of having more CVRF, respectively.

CONCLUSIONS

We found high prevalence of multiple CVRF in children with mild to moderate CKD. Children with glomerular disease may be at higher risk for future cardiovascular events.

Predictive power of hepatitis B 1762T/1764A mutations in plasma for hepatocellular carcinoma risk in Qidong, China

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality with nearly 700,000 deaths occurring annually. Hepatitis B virus (HBV) is a major contributor to HCC and acquired mutations in the HBV genome may accelerate its pathogenesis. In this study, a matched case-control investigation of 345 men who died of HCC and 625 controls were nested within a cohort of male hepatitis B surface antigen (HBsAg) carriers from Qidong, China. Matched preserving odds ratios (ORs) were used as a measure of association and 95% confidence intervals (CIs) as a measure of precision. Real-time polymerase chain reaction allowed for a quantitative comparison of the levels of the HBV 1762(T)/1764(A) mutation in cases and controls. A total of 278 (81%) of the cases were positive for the HBV 1762(T)/1764(A) mutation compared with 250 (40%) of the controls. The matched preserving OR of 6.72 (95% CI: 4.66 to 9.68) strongly indicated that cases were significantly more probably than controls to have the mutation. Plasma levels of DNA harboring the HBV mutation were on average 15-fold higher in cases compared with controls (P < 0.001). Most strikingly, the level of the mutation in the 20 controls who later developed and died of HCC were on average 274-fold higher than controls who did not develop HCC. Thus, within this cohort of HBsAg carriers at high risk of developing HCC, individuals positive for the HBV 1762(T)/1764(A) mutation at enrollment were substantially more probably to subsequently develop HCC, with a higher concentration of the mutation in plasma enhancing predisposition for cancer development.

Sex differences in the clinical and serologic presentation of early Lyme disease: Results from a retrospective review

BACKGROUND

Lyme disease is the most common vector-borne disease in the United States, and the number of reported cases has more than doubled between 1992 and 2008. Few studies have explicitly examined sex-based differences in the clinical presentation of or serologic response to early Lyme disease. It is unknown whether the sex-based variability observed in other infectious diseases is relevant to this clinical setting.

OBJECTIVE

This study retrospectively examined clinical and serologic differences by sex among a community case series of patients with a current or past episode of confirmed early Lyme disease.

METHODS

This was a retrospective, consecutive case series of adult patients in Maryland enrolled from August 2002 to August 2007 meeting criteria for a current or past episode of confirmed early Lyme disease. Clinical variables and patients' self-report surrounding illness onset were abstracted through chart review. All serologic tests drawn within 3 months of illness onset were interpreted using Centers for Disease Control and Prevention criteria.

RESULTS

In a total of 125 patients, there were no significant differences in clinical presentation by sex. The initial self-misdiagnosis rates for men and women were 10% and 18%, respectively (P = NS). Among the 62 patients with a serologic test as part of their clinical evaluation, 50% of men had a positive, 2-tier result compared with 32% of women (P = NS). Among the 41 patients with a positive ELISA, median ELISA values (3.4 vs 2.0; P = 0.03) and median number of immunoglobulin G (IgG) bands (4 vs 2; P = 0.03) were significantly higher among men.

CONCLUSIONS

In this small, retrospective sample, we found evidence for sex-based differences in the magnitude of ELISA and IgG serologic response to early Lyme disease. Such differences could have implications for appropriate diagnosis, treatment, and disease classification. Larger, prospective studies are needed to replicate the results found in this study and to examine their relationship to sex-based immunologic variability.

HIV, HAART, and lipoprotein particle concentrations in the Women's Interagency HIV Study

BACKGROUND

Changes in lipoprotein particle concentrations, especially greater small low-density lipoprotein particle (LDL-p) and lower small high-density lipoprotein particle (HDL-p) may provide information regarding cardiovascular disease (CVD) risk above and beyond that which is provided by standard lipids. We quantified the association HIV and HAART use had with LDL-p and HDL-p.

METHODS

Cross-sectional study of 1077 individuals classified by HIV/HAART status (361 HIV-uninfected, 128 HIV-infected/HAART naive, 588 HIV-infected/on HAART) enrolled in the Women's Interagency HIV Study. Nuclear magnetic resonance spectroscopy estimated total and subclass lipoprotein particle concentrations. Quantile regression models were used to estimate differences in the 10th, 25th, 50th, 75th, and 90th percentiles of the distributions of lipoprotein particle concentrations between the two HIV-infected exposure groups and HIV-uninfected controls after adjustment for demographic, nonlipid metabolic factors, and standard lipids.

RESULTS

Compared with HIV-uninfected women, those on HAART had greater 75th and 90th percentiles of small LDL-p; there was little difference between HIV-infected/HAART naive and HIV-uninfected women. After adjustment for triglycerides, the association of HAART with greater 75th and 90th percentiles of small LDL-p was attenuated and no longer significant. In contrast, after adjustment for triglycerides, HIV infection irrespective of HAART status remained associated with significantly lower 10th, 25th, 50th, 75th, and 90th percentiles of small HDL-p.

CONCLUSION

Our findings suggest that testing for LDL-p confers little additional information beyond triglycerides levels when assessing CVD risk. Further investigation is needed to examine the role of HDL-p in the link between HIV and CVD in women.

The association between abnormal birth history and growth in children with CKD

BACKGROUND AND OBJECTIVES

Poor linear growth is a well described complication of chronic kidney disease (CKD). This study evaluated whether abnormal birth history defined by low birth weight (LBW; <2500 g), prematurity (gestational age <36 weeks), small for gestational age (SGA; birth weight <10th percentile for gestational age), or intensive care unit (ICU) at birth were risk factors for poor growth outcomes in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Growth outcomes were quantified by age-sex-specific height and weight z-scores during 1393 visits from 426 participants of the Chronic Kidney Disease in Children Study, an observational cohort of children with CKD. Median baseline GFR was 42.9 ml/min per 1.73 m(2), 21% had a glomerular diagnosis, and 52% had CKD for ≥ 90% of their lifetime.

RESULTS

A high prevalence of LBW (17%), SGA (14%), prematurity (12%), and ICU after delivery (40%) was observed. Multivariate analyses demonstrated a negative effect of LBW (-0.43 ± 0.14; P < 0.01 for height and -0.37 ± 0.16; P = 0.02 for weight) and of SGA (-0.29 ± 0.16; P = 0.07 for height and -0.41 ± 0.19; P = 0.03 for weight) on current height and weight. In children with glomerular versus nonglomerular diagnoses, the effect of SGA (-1.08 versus -0.18; P = 0.029) on attained weight was more pronounced in children with a glomerular diagnosis.

CONCLUSIONS

LBW and SGA are novel risk factors for short stature and lower weight percentiles in children with mild to moderate CKD independent of kidney function.

Transport, separation, and accumulation of proteins on supported lipid bilayers

Transport, separation, and accumulation of proteins in their natural environment are central goals in protein biotechnology. Miniaturized assays of supported lipid bilayers (SLBs) have been proposed as promising candidates to realize such technology on a chip, but a modular system for the controlled transport of membrane proteins does not exist. In this letter, we demonstrate that standing surface acoustic waves drive the in-plane redistribution of proteins on planar SLBs over macroscopic distances (3.5 mm). Accumulation of proteins in periodic patterns of about 10-fold protein concentration difference is accomplished and shown to relax into the homogeneous state by diffusion. Different proteins separate in individual fractions from a homogeneous distribution and are transported and accumulated into clusters using beats. The modular planar setup has the potential of integrating other lab-on-a-chip tools, for monitoring the membrane-protein integrity or adding microfluidic features for blood screening or DNA analysis.

Thermomechanic-electrical coupling in phospholipid monolayers near the critical point

Lipid monolayers have been shown to represent a powerful tool in studying mechanical and thermodynamic properties of lipid membranes as well as their interaction with proteins. Using Einstein's theory of fluctuations we here demonstrate that an experimentally derived linear relationship both between transition entropy S and area A as well as between transition entropy and charge q implies a linear relationships between compressibility κT, heat capacity cπ, thermal expansion coefficient αT, and electric capacity CT. We demonstrate that these couplings have strong predictive power as they allow calculating electrical and thermal properties from mechanical measurements. The precision of the prediction increases as the critical point TC is approached.

Acoustic driven flow and lattice Boltzmann simulations to study cell adhesion in biofunctionalized mu-fluidic channels with complex geometry

Accurately mimicking the complexity of microvascular systems calls for a technology which can accommodate particularly small sample volumes while retaining a large degree of freedom in channel geometry and keeping the price considerably low to allow for high throughput experiments. Here, we demonstrate that the use of surface acoustic wave driven microfluidics systems successfully allows the study of the interrelation between melanoma cell adhesion, the matrix protein collagen type I, the blood clotting factor von Willebrand factor (vWF), and microfluidic channel geometry. The versatility of the tool presented enables us to examine cell adhesion under flow in straight and bifurcated microfluidic channels in the presence of different protein coatings. We show that the addition of vWF tremendously increases (up to tenfold) the adhesion of melanoma cells even under fairly low shear flow conditions. This effect is altered in the presence of bifurcated channels demonstrating the importance of an elaborate hydrodynamic analysis to differentiate between physical and biological effects. Therefore, computer simulations have been performed along with the experiments to reveal the entire flow profile in the channel. We conclude that a combination of theory and experiment will lead to a consistent explanation of cell adhesion, and will optimize the potential of microfluidic experiments to further unravel the relation between blood clotting factors, cell adhesion molecules, cancer cell spreading, and the hydrodynamic conditions in our microcirculatory system.

Sleep and fatigue symptoms in children and adolescents with CKD: a cross-sectional analysis from the chronic kidney disease in children (CKiD) study

BACKGROUND

Although symptoms of sleepiness and fatigue are common in adults with chronic kidney disease (CKD), little is known about the prevalence of these symptoms in children with CKD.

STUDY DESIGN

Cross-sectional analysis within a cohort study.

SETTING & PARTICIPANTS

We describe the frequency and severity of sleep problems and fatigue and assess the extent of their association with measured glomerular filtration rate (mGFR) and health-related quality of life (HRQOL) in 301 participants of the Chronic Kidney Disease in Children cohort.

OUTCOMES & MEASUREMENTS

Sleep and fatigue-related items from the Pediatric Quality of Life Inventory 4.0 Generic Scales and the CKD-related Symptoms List were used.

RESULTS

Median mGFR was 42.0 mL/min/1.73 m(2) (25th-75th percentiles, 31.2-53.2), and median age was 13.9 years (25th-75th percentiles, 10.8-16.2). Children with mGFR of 40-<50, 30-<40, or <30 mL/min/1.73 m(2) had 2.07 (95% CI, 1.05-4.09), 2.35 (95% CI, 1.17-4.72), and 2.59 (95% CI, 1.15-5.85) higher odds of having more severe parent reports of low energy than children with mGFR > or = 50 mL/min/1.73 m(2). Compared with participants with mGFR > or = 50 mL/min/1.73 m(2), those with mGFR < 30 mL/min/1.73 m(2) had 3.92 (95% CI, 1.37-11.17) higher odds of reporting more severe weakness, and those with mGFR of 40-<50 mL/min/1.73 m(2) had 2.95 (95% CI, 1.26-6.88) higher odds of falling asleep during the day. Low energy, trouble sleeping, and weakness were associated with lower HRQOL scores.

LIMITATIONS

Symptoms of sleep and fatigue represent the child's or parent's perception of symptom severity, whereas individual items can lead to imprecise measurements of sleep and fatigue.

CONCLUSIONS

Lower mGFR was associated with increased weakness, low energy, and daytime sleepiness. Furthermore, a strong association between trouble sleeping, low energy, and weakness with decreases in overall HRQOL was observed. Detection and treatment of poor sleep and fatigue may improve the development and HRQOL of children and adolescents with CKD.

Phase-state dependent current fluctuations in pure lipid membranes

Current fluctuations in pure lipid membranes have been shown to occur under the influence of transmembrane electric fields (electroporation) as well as a result from structural rearrangements of the lipid bilayer during phase transition (soft perforation). We demonstrate that the ion permeability during lipid phase transition exhibits the same qualitative temperature dependence as the macroscopic heat capacity of a D15PC/DOPC vesicle suspension. Microscopic current fluctuations show distinct characteristics for each individual phase state. Although current fluctuations in the fluid phase show spikelike behavior of short timescales (approximately 2 ms) with a narrow amplitude distribution, the current fluctuations during lipid phase transition appear in distinct steps with timescales of approximately 20 ms. We propose a theoretical explanation for the origin of timescales and permeability based on a linear relationship between lipid membrane susceptibilities and relaxation times near the phase transition.

Multiple-infection and recombination in HIV-1 within a longitudinal cohort of women

Background

Recombination between strains of HIV-1 only occurs in individuals with multiple infections, and the incidence of recombinant forms implies that multiple infection is common. Most direct studies indicate that multiple infection is rare. We determined the rate of multiple infection in a longitudinal study of 58 HIV-1 positive participants from The Women's Interagency HIV Study with a richer sampling design than previous direct studies, and we investigated the role of recombination and sampling design on estimating the multiple infection rate.

Results

40% of our sample had multiple HIV-1 infections. This rate of multiple infection is statistically consistent with previous studies once differences in sampling design are taken into account. Injection drug use significantly increased the incidence of multiple infections. In general there was rapid elimination of secondary strains to undetectable levels, but in 3 cases a superinfecting strain displaced the initial infecting strain and in two cases the strains coexisted throughout the study. All but one secondary strain was detected as an inter- and/or intra-genic recombinant. Injection drug use significantly increased the rate of observed recombinants.

Conclusion

Our multiple infection rate is consistent with rates estimated from the frequency of recombinant forms of HIV-1. The fact that our results are also consistent with previous direct studies that had reported a much lower rate illustrates the critical role of sampling design in estimating this rate. Multiple infection and recombination significantly add to the genetic diversity of HIV-1 and its evolutionary potential, and injection drug use significantly increases both.

Phase transition induced fission in lipid vesicles

In this work we demonstrate how the first order phase transition in giant unilamellar vesicles (GUVs) can function as a trigger for membrane fission. When driven through their gel-fluid phase transition GUVs exhibit budding or pearl formation. These buds remain connected to the mother vesicle presumably by a small neck. Cooling these vesicles from the fluid phase (T>T(m)) through the phase transition into the gel state (T<T(m)), leads to complete rupture and fission of the neck, while the mother vesicle remains intact. Pearling tubes which formed upon heating break-up and decay into multiple individual vesicles which then diffuse freely. Finally we demonstrate that mimicking the intracellular bulk viscosity by increasing the bulk viscosity to 40 cP does not affect the overall fission process, but leads to a significant decrease in the size of the released vesicles.

Association of child care burden and household composition with adherence to highly active antiretroviral therapy in the Women's Interagency HIV Study

Our objective was to describe the association that childcare burden, household composition, and health care utilization have with adherence to highly active antiretroviral therapy (HAART) among women in the United States. The primary outcome was 95% or more adherence to HAART evaluated at 10,916 semiannual visits between October 1998 and March 2006 among 1419 HIV-infected participants enrolled in the Women's Interagency HIV Study. HAART adherence levels of 95% or more were reported at 76% of the semiannual visits. At only 4% of the person-visits did women report either quite a bit or extreme difficulty in caring for child; at 52% of the person-visits women reported at least one child 18 years of age or older living in the household. We found a one-unit increase in the difficulty in caring for children (childcare burden was assessed on a 5-point scale: not difficult [1] to extremely difficult [5]) was associated with a 6% decreased odds of 95% or more HAART adherence (adjusted odds ratio [OR] = 0.94; p = 0.07). Each additional child 18 years of age or less living in the household was associated with an 8% decreased odds of 95% or more adherence (adjusted OR = 0.92, p = 0.03). Both the number and type of adult living in the household, as well as health care utilization were not associated with HAART adherence. Greater child care burden and number of children 18 years old or younger living in household were both inversely associated with HAART adherence. Assessing patients' difficulties in caring for children and household composition are important factors to consider when addressing adherence to HAART.

New equations to estimate GFR in children with CKD

The Schwartz formula was devised in the mid-1970s to estimate GFR in children. Recent data suggest that this formula currently overestimates GFR as measured by plasma disappearance of iohexol, likely a result of a change in methods used to measure creatinine. Here, we developed equations to estimate GFR using data from the baseline visits of 349 children (aged 1 to 16 yr) in the Chronic Kidney Disease in Children (CKiD) cohort. Median iohexol-GFR (iGFR) was 41.3 ml/min per 1.73 m(2) (interquartile range 32.0 to 51.7), and median serum creatinine was 1.3 mg/dl. We performed linear regression analyses assessing precision, goodness of fit, and accuracy to develop improvements in the GFR estimating formula, which was based on height, serum creatinine, cystatin C, blood urea nitrogen, and gender. The best equation was: GFR(ml/min per 1.73 m(2))=39.1[height (m)/Scr (mg/dl)](0.516) x [1.8/cystatin C (mg/L)](0.294)[30/BUN (mg/dl)](0.169)[1.099](male)[height (m)/1.4](0.188). This formula yielded 87.7% of estimated GFR within 30% of the iGFR, and 45.6% within 10%. In a test set of 168 CKiD patients at 1 yr of follow-up, this formula compared favorably with previously published estimating equations for children. Furthermore, with height measured in cm, a bedside calculation of 0.413*(height/serum creatinine), provides a good approximation to the estimated GFR formula. Additional studies of children with higher GFR are needed to validate these formulas for use in screening all children for CKD.