Browsing by Author "Wenger, Julia"

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    Fatty acids and other risk factors for sudden cardiac death in patients starting hemodialysis
    (Karger, 2013) Friedman, Allon N.; Yu, Zhangsheng; Denski, Cheryl; Tamez, Hector; Wenger, Julia; Thadhani, Ravi; Li, Yong; Watkins, Bruce; Medicine, School of Medicine
    Background: Little is known about risk factors for sudden cardiac death in hemodialysis patients during the high-risk first year of dialysis. We therefore undertook to identify such risk factors in a nationally representative cohort and were able to include baseline levels of blood fatty acids, some of which influence arrhythmogenicity and sudden cardiac death risk. Design: The study cohort included 100 patients who died of sudden cardiac death during the first year of hemodialysis and 300 frequency-matched controls. Using the elastic net statistical method, numerous demographic and clinical characteristics were included with baseline total serum levels for 11 major fatty acids (model 1) and with serum phospholipid fractions of these same fatty acids (model 2). Final models included only covariates that had a non-zero coefficient. Results: In model 1, serum albumin [odds ratio (95% CI): 0.55 (0.33-0.93); p = 0.03] and total serum long-chain n-3 docosapentaenoic acid [0.70 (0.51-0.97); p = 0.03] were inversely associated with the odds of sudden cardiac death, while the total serum saturated fatty acid level had a direct association [1.01 (1.00-1.02); p = 0.03]. In model 2, serum albumin and docosapentaenoic acid remained inversely associated with sudden cardiac death in a similar manner as in model 1. Pulse pressure also had an inverse association [0.96 (0.93-1.00); p < 0.05]. Conclusions: Several factors, including blood content of docosapentaenoic acid and saturated fatty acids, were associated with the odds of sudden cardiac death during year one of hemodialysis. These results raise the possibility that dietary modification may reduce sudden death risk.
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    Inverse relationship between long chain n-3 fatty acids and risk of sudden cardiac death in patients starting hemodialysis
    (Elsevier, 2013) Friedman, Allon N.; Yu, Zhangsheng; Tabbey, Rebeka; Denski, Cheryl; Tamez, Hector; Wenger, Julia; Thadhani, Ravi; Li, Yong; Watkins, Bruce; Medicine, School of Medicine
    Experimental and clinical evidence suggests that long-chain n-3 fatty acids may protect against sudden cardiac death, the leading cause of mortality in hemodialysis patients. Here we investigated whether long-chain n-3 fatty acids have a protective relationship with sudden cardiac death in 100 patients who died of sudden cardiac death during the first year of starting hemodialysis and 300 patients who survived. Individuals were selected from a nationally representative cohort of over 1000 US hemodialysis units in 2004-2005. The odds of sudden cardiac death were calculated by quartile of long-chain n-3 fatty acid levels over the first year. There was a significant inverse relationship between long-chain n-3 fatty acids and the risk of sudden cardiac death even after adjusting for relevant comorbid conditions, biochemical values, and dietary fats. The odds of sudden cardiac death at 1 year for the second, third, and fourth quartile groups of long-chain n-3 fatty acids were 0.37, 0.22, and 0.20, respectively, compared with the lowest quartile. This significant inverse relationship was maintained even during the highest-risk first few months on hemodialysis. Thus, long-chain n-3 fatty acids are strongly and independently associated with a lower risk of sudden cardiac death in hemodialysis patients throughout the first year of hemodialysis.
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    Low Blood Levels of Long Chain n-3 Polyunsaturated Fatty Acids in U.S. Hemodialysis Patients: Clinical Implications
    (Karger, 2012) Friedman, Allon N.; Yu, Zhangsheng; Tabbey, Rebeka; Denski, Cheryl; Tamez, Hector; Wenger, Julia; Thadhani, Ravi; Li, Yong; Watkins, Bruce A.; Medicine, School of Medicine
    Background: Cardioprotective and other clinical benefits of long-chain n-3 polyunsaturated fatty acids (PUFA) are inversely related to dietary intake and hence blood content. We therefore investigated, in the first study of its kind, the blood content and distribution of these fatty acids in a large representative population of US hemodialysis patients. Methods: Frozen sera were obtained from 400 individuals who were part of a large, contemporary, representative cohort of US incident hemodialysis patients. Long-chain n-3 PUFA were measured in total serum lipids and in the neutral and polar serum fractions using gas chromatography and solid phase extraction techniques. Mean long-chain n-3 PUFA levels were compared to levels in other dialysis and nondialysis populations from published reports. Results: The study population was qualitatively similar to the overall US hemodialysis population in terms of major clinical characteristics. Long-chain n-3 PUFA were present in the serum polar fraction, with essentially none being detected in the neutral fraction (p < 0.0001 for polar vs. neutral fractions for all three long-chain n-3 PUFA). Mean serum long-chain n-3 PUFA levels (weight percent (±SD): total 1.55 ± 0.95, polar 3.99 ± 1.45) were low compared to nondialysis and most other non-US hemodialysis cohorts. Conclusions: While US hemodialysis patients have a blood distribution of long-chain n-3 PUFA that is similar to that in the general population, blood content is among the lowest recorded in the medical literature. This has implications for renal dietary recommendations and makes US patients an ideal group for testing the clinical effects of long-chain n-3 PUFA supplementation.
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    Serum phospholipid fraction of polyunsaturated fatty acids is the preferred indicator for nutrition and health status in hemodialysis patients
    (Elsevier, 2016-12) Watkins, Bruce A.; Kim, Jeffrey; Tamez, Hector; Wenger, Julia; Thadhani, Ravi; Friedman, Allon N.; Department of Medicine, IU School of Medicine
    Long chain (LC) polyunsaturated fatty acids (PUFA) are major components of cell membrane phospholipids (PL) and serve as precursors for numerous bioactive lipid derivatives. Fatty acids (FA) are routinely analyzed in biological samples to assess composition of tissues, cells, and lipid fractions. In human studies, serum or plasma is often used because of their easy procurement. However, the lipid pool in serum and plasma is a mixture of triacylglycerol (TG), PL, cholesterol and its esters, and other components. Herein, we report findings from a serum FA analysis after fractionation of polar and neutral lipids by solid phase extraction in a large cohort of 400 hemodialysis patients. LC PUFA were found concentrated in the polar fraction compared to the total or the neutral lipid fraction. When correlated with clinical markers of disease, a greater number of significant correlations were found for PUFA in polar compared to total or the neutral fraction. We also observed that polar lipids are a reliable reflection of LC PUFA status compared to the total or neutral fractions because the latter are diluted by non-essential FA. The relative amounts of LC PUFA in the total and neutral fractions reflect the contribution of TG in blood that varies with diet, age, and physiologic state. Our data indicate that LC PUFA in the polar fraction are superior indicators of bioactive FA-status than in the total or the neutral fraction and should be used to establish important links between PUFA status, their bioactive substrates in hemodialysis patients.