Amino acid repletion does not decrease muscle protein catabolism during hemodialysis.

Intradialytic protein catabolism is attributed to loss of amino acids in the dialysate. We investigated the effect of amino acid infusion during hemodialysis (HD) on muscle protein turnover and amino acid transport kinetics by using stable isotopes of phenylalanine, leucine, and lysine in eight patients with end-stage renal disease (ESRD). Subjects were studied at baseline (pre-HD), 2 h of HD without amino acid infusion (HD-O), and 2 h of HD with amino acid infusion (HD+AA). Amino acid depletion during HD-O augmented the outward transport of amino acids from muscle into the vein. Increased delivery of amino acids to the leg during HD+AA facilitated the transport of amino acids from the artery into the intracellular compartment. Increase in muscle protein breakdown was more than the increase in synthesis during HD-O (46.7 vs. 22.3%, P < 0.001). Net balance (nmol.min(-1).100 ml (-1)) was more negative during HD-O compared with pre-HD (-33.7 +/- 1.5 vs. -6.0 +/- 2.3, P < 0.001). Despite an abundant supply of amino acids, the net balance (-16.9 +/- 1.8) did not switch from net release to net uptake. HD+AA induced a proportional increase in muscle protein synthesis and catabolism. Branched chain amino acid catabolism increased significantly from baseline during HD-O and did not decrease during HD+AA. Protein synthesis efficiency, the fraction of amino acid in the intracellular pool that is utilized for muscle protein synthesis decreased from 42.1% pre-HD to 33.7 and 32.6% during HD-O and HD+AA, respectively (P < 0.01). Thus amino acid repletion during HD increased muscle protein synthesis but did not decrease muscle protein breakdown.

Characteristics of end stage renal disease diabetic patients in two countries with different socioeconomic conditions.

PURPOSE: To identify differences that may affect morbidity and mortality of type 2 diabetic patients reaching ESRD between countries with different socioeconomic conditions. METHODS: Comparison of clinical and laboratory features between 21 Nigerian (N) and 57 American patients (A) reaching ESRD over a 30 month period. RESULTS: Differences were noted in age at ESRD (N, 55.5+/-9.8; A, 64.5+/-9.6 years), duration of diabetes (N, 5.2+/-2.8, A: 14.9+/-4.9 years), body mass index (N, 24.5+/-4.1; A; 27.6+/-6.3 kg/m2), prevalence of left ventricular hypertrophy (N; 14%; A, 89%) and ischemic heart disease (N, 26%; A, 67%), blood pressure (N, [166.2+/-26.7]/[98.6+/-16.5] mmHg; A, [146.8+/-23.6]/[72.5+/-13.3] mmHg), creatinine clearance (N, 6.1+/-3.6; A, 14.8+/-3.5 ml/min), urine protein excretion (N, 1.2+/-0.7; A, 6.1+/-4.9 g/24-h), hematocrit (N, 28.0+/-6.0; A, 35.0+/-5.0%), serum glucose (N, 5.6+/-1.6; A, 10.5+/-5.5 mmol/l), and serum cholesterol (N, 5.32+/-2.57; A, 4.19+/-1.16 mmol/l) (all at P < or = 0.05). Differences were also found in the number of antihypertensive medications (N 1.4+/-0.6; A 2.4+/-1.2 per patient), and use of medications for diabetes (N 29%, A 79%), statins (N zero, A 61 %) and erythropoietin (N zero, A 39%). 72% of the A, but none of the N patients had a functional dialysis access prior to ESRD. CONCLUSIONS: Between A and N patients reaching ESRD, there are differences in clinical features and laboratory values that may affect morbidity, mortality and impact on the health care resources. These differences indicate areas where further studies that could assist in the planning for ESRD care in both Nigeria and USA are required.

Protein turnover and amino acid transport kinetics in end-stage renal disease.

Protein and amino acid metabolism is abnormal in end-stage renal disease (ESRD). Protein turnover is influenced by transmembrane amino acid transport. The effect of ESRD and hemodialysis (HD) on intracellular amino acid transport kinetics is unknown. We studied intracellular amino acid transport kinetics and protein turnover by use of stable isotopes of phenylalanine, leucine, lysine, alanine, and glutamine before and during HD in six ESRD patients. Data obtained from amino acid concentrations and enrichment in the artery, vein, and muscle compartments were used to calculate intracellular amino acid transport and muscle protein synthesis and catabolism. Fractional muscle protein synthesis (FSR) was estimated by the precursor product approach. Despite a significant decrease in the plasma concentrations of amino acids in the artery and vein during HD, the intracellular concentrations remained stable. Outward transport of the amino acids was significantly higher than the inward transport during HD. FSR increased during HD (0.0521 +/- 0.0043 vs. 0.0772 +/- 0.0055%/h, P < 0.01). Results derived from compartmental modeling indicated that both protein synthesis (118.3 +/- 20.6 vs. 146.5 +/- 20.6 nmol.min-1.100 ml leg-1, P < 0.01) and catabolism (119.8 +/- 18.0 vs. 174.0 +/- 14.2 nmol.min-1.100 ml leg-1, P < 0.01) increased during HD. However, the intradialytic increase in catabolism exceeded that of synthesis (57.8 +/- 13.8 vs. 28.0 +/- 8.5%, P < 0.05). Thus HD alters amino acid transport kinetics and increases protein turnover, with net increase in protein catabolism.

Relation between access-related Infection and preinfection serum albumin concentration in patients on chronic hemodialysis.

BACKGROUND: Hemodialysis (HD) access-related infection is a major cause of morbidity and mortality in HD patients. We tested whether hypoalbuminemia is a risk factor for HD access infection and whether mortality of HD catheter infection is affected by removal of the infected catheter. METHODS: We analyzed the records of 87 patients on chronic HD who were hospitalized for HD access-related infection. We obtained data on age, sex, preinfection serum albumin level, comorbidities, complications, infecting organism, type of infection, mode of management, and mortality. We compared preinfection serum albumin levels in 79 patients with HD access infection with the serum albumin levels of 198 control patients on chronic HD without HD access infection admitted to the hospital during the same time for other reasons. In the HD catheter infection subgroup, we compared mortalities between patients treated with catheter removal plus antibiotics as the primary mode of management and those treated initially with antibiotics alone. RESULTS: Preadmission serum albumin level was lower in the HD access infection group (2.4 +/- 0.6 g/dL) than in the control group (3.2 +/- 0.6 g/dL, P < 0.0001). Logistic regression identified preadmission serum albumin level as a strong independent predictor of HD access infection. In a logistic regression model, with age, sex, HIV status, diabetes, and type of HD vascular access (excluding arterovenous fistula) as the covariates, the odds ratio of HD access infection was 9.8 (95% confidence interval [CI] 4.9-19.7) for a serum albumin level