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Nutrition in CAPD: Serum bicarbonate and the ubiquitin-proteasome system in muscle. Background Metabolic acidosis in chronic renal failure (CRF) induces loss of lean body mass while elimination of acidosis during a one year trial improved anthropometric indices in continuous ambulatory peritoneal dialysis (CAPD) patients. In rats with CRF, the mechanisms causing loss of lean body mass have been linked to acidosis-induced destruction of the essential, branched-chain amino acids (BCAA) and activation of the ubiquitin-proteasome system that degrades muscle protein; the latter response includes increased transcription of the ubiquitin gene. Method Our aim was to determine if increasing the serum bicarbonate (HCO 3 ) concentration of CAPD patients would improve their nutritional status, increase plasma BCAA levels, and reduce ubiquitin mRNA in their muscle as an index of suppressed activity of the ubiquitin-proteasome system. Eight, stable, long-term CAPD patients underwent vastus lateralis muscle biopsy before being randomized to continue 35 mmol/L lactate dialysate or convert to a 40 mmol/L lactate dialysate. After four weeks, measurements were repeated. Results Serum HCO 3 increased in all patients and final values did not differ statistically between the two groups so results for all patients were combined. Weight and body mass index increased significantly as did plasma BCAA. Muscle levels of ubiquitin mRNA decreased significantly; serum tumor necrosis factor-α (TNF-α) also decreased. Conclusion Our results indicate that even a small correction of serum HCO 3 improves nutritional status, and provide evidence for down-regulation of BCAA degradation and muscle proteolysis via the ubiquitin-proteasome system. Whether acidosis and inflammatory cytokines (such as, TNF-α) interact to impair nutrition is unknown.

Short daily hemodialysis rapidly improves nutritional status in hemodialysis patients.BackgroundMalnutrition is a common problem in maintenance hemodialysis patients and is associated with increased mortality and morbidity. Interventions such as oral or intravenous nutritional supplements have often failed to improve nutritional status. We studied the effect of a daily dialysis program on nutritional parameters.MethodsEight patients treated with standard hemodialysis (SHD) 4 to 5 hours three times per week were converted to daily hemodialysis (DHD) 2 to 2.5 hours six times per week. Serum albumin, prealbumin, and total cholesterol were evaluated every three months. Anthropometry and dietary evaluation were performed every six months.ResultsSerum albumin rose from 39.0 ± 2.6 to 42.0 ± 3.1 and 43.0 ± 2.6 g/L, prealbumin from 0.36 ± 0.04 to 0.41 ± 0.05 and 0.42 ± 0.1 g/L, total cholesterol from 1.7 ± 0.4 to 1.9 ± 0.4 and 1.8 ±0.3 g/L at baseline and at 6 and 12 months, respectively, after switching patients to DHD. Daily protein intake increased from 1.29 ± 0.20 g/kg/day to 1.48 ± 0.60 and 1.90 ± 0.70 (P < 0.05). These changes were accompanied by a dry body weight increase of 2.4 ± 1.6kg (P < 0.005) at month 6 and 4.2 ± 2.8kg at one year (P < 0.05). Lean body mass increased from 47.7 ± 4.9kg to 49.1 ± 5.9 (P < 0.05) and 50.5 ± 6.2 (P < 0.05).ConclusionsDaily hemodialysis appears to be a suitable method to improve nutritional status in maintenance dialysis patients.

Nutritional aspects in hemodialysis. The results of cross sectional studies throughout the world indicate that maintenance hemodialysis patients are at risk of malnutrition. Longitudinal studies show that malnutrition is associated with a reduced life expectancy mainly because of cardiovascular and infectious complications. Several factors are responsible for malnutrition of hemodialysis patients. Protein-energy intake is often reduced because of inappropriate dietary restrictions, anorexia, and taste alterations, promoting malnutrition in most patients entering dialysis. Intercurrent illnesses and frequent hospitalizations add to meal disturbances. A state of persistent catabolism may result from acidosis, resistance to anabolic factors such as growth hormone, insulin, and insulin-like growth factor-1, as well as a chronic inflammatory state caused by dialysis membrane and fluid bioincompatibility. In addition, losses of nutrients, including glucose, amino acids, proteins, and vitamins, occur during the dialysis treatment. Careful monitoring of dietary intakes is mandatory even in predialysis patients. In hemodialysis patients, the dose of dialysis should be adapted to correct acidosis and to relieve anorexia caused by accumulation of uremic toxins and hyperleptinemia. When malnutrition is established, active therapeutic interventions should take place, including intradialytic parenteral nutrition if oral supplementation has failed to improve nutritional status. Anabolism has been observed during the administration of recombinant growth hormone and insulin-like growth factor-1. Emerging therapeutic strategies against malnutrition may also involve a short period of daily dialysis.

Effects of an amino acid dialysate on leucine metabolism in continuous ambulatory peritoneal dialysis patients.BackgroundProtein-energy malnutrition is frequent in continuous ambulatory peritoneal dialysis (CAPD) patients. The use of amino acids in the dialysate could improve the protein balance, especially if associated to a concomitant energy intake.MethodsA 1.1% amino acid solution for peritoneal dialysis was administered to CAPD patients over 30 minutes during concomitant absorption of 600 ml water (control study) or of a 600 kcal meal/600 ml. Leucine metabolism was studied using the combination of intravenous [2H3] and intraperitoneal [13C] leucine.ResultsThe rate of leucine appearance was stimulated by 56 and 53% (control and meal) at 45 minutes. The rates of leucine appearance and disappearance were lower from 180 to 300 minutes during the meal versus control study (P < 0.05). Proteolysis was unaffected during the control study and was inhibited by 25% during the meal study (P < 0.05). During the five-hour cycle dialysis with or without a meal, 80% of the leucine administered into the peritoneum was absorbed. Forty-one percent was retained in the splanchnic bed. Forty-three percent was used for protein synthesis, and 16% was oxidized.ConclusionsThis amino acids solution is efficaciously utilized for protein synthesis in CAPD patients with no effect on protein breakdown. The concomitant ingestion of a carbohydrate-lipid meal inhibits protein breakdown and reinforces a positive effect of the amino acids solution on protein balance.