Contrast agent nephrotoxicity: comparison of ionic and nonionic contrast agents

The effects on glomerular and proximal tubular function of an ionic contrast agent (sodium meglumine diatrizoate) and a nonionic agent (iopamidol) were compared in 34 patients with normal renal function. The patients received large doses (2.5 ml/kg body weight) of contrast material for IV digital subtraction angiography. Urine samples, collected before, immediately after, and on the first and third days after digital subtraction angiography, were analyzed for albumin, alanil-aminopeptidase, alpha-glucosidase, and beta-2-microglobulin. The changes noted were mild and of short duration with both contrast agents, despite the high dose given. These results suggest that, at least as far as renal toxicity is measured by these tests is concerned, ionic monomers can be safely used instead of more expensive nonionic media in procedures, such as digital subtraction angiography, that require high doses of contrast material.

Muscle biopsy studies in chronically uremic patients: evidence for malnutrition

Evidence for muscle protein wasting and abnormal muscle metabolism is common in uremia. Muscle DNA content is considered a reliable reference standard in normal and undernourished adults. Muscle RNA content rapidly changes during starvation and refeeding. The ratio of noncollagen alkali-soluble proteins (ASP) to DNA is considered to be an estimate of the cytoplasmic volume of a single cell, and the RNA: DNA ratio is an index of the ribosomal capacity for protein synthesis. Muscle DNA, RNA, ASP, water, and fat content were determined in muscle biopsy specimens from chronically uremic patients receiving conservative treatment (CT), maintenance hemodialysis (two centers), or CAPD. Nutrient intake was low and the anthropometric indices were decreased in all groups of patients, except in the hemodialysis patients from one center. Serum proteins and muscle ASP: DNA and RNA: DNA ratios were decreased. The nutritional status was reassessed in some malnourished CAPD patients after about one year of careful nutritional advice and was unchanged. These results suggest that chronically uremic patients on CT are often malnourished, primarily because of an inadequate protein and/or energy intake. Muscle nucleic acid and protein content are useful tools for nutritional assessment at a cellular level in humans with chronic renal failure and can be used to monitor the response to nutritional therapy.

Simple methods for nutritional assessment in hemodialyzed patients

Uremic patients undergoing hemodialysis are often catabolic and malnourished. To treat malnutrition effectively, a preliminary nutritional assessment is needed. Available techniques should enable the clinician to readily detect the presence of malnutrition and to follow the response to nutritional therapy. In a group of chronic uremic patients undergoing maintenance hemodialysis, the authors evaluated the nutritional status with the following indices: 1) assessment of the somatic fat and protein compartments by means of anthropometric measurements (weight/height ratio, triceps and subscapular skinfold thickness, and arm muscle circumference); 2) assessment of the visceral protein compartment (serum total protein, albumin, transferrin, pseudocholinesterase, C3, and immunoglobulin content); 3) assessment of cell-mediated immunity by means of skin tests ("skin window," PPD and phytohemagglutinin) and blood lymphocyte content; and 4) assessment of the dietary intake of nutrients with dietary diaries. Anthropometric indices, serum protein content (except immunoglobulins), and the immune response was generally lower than in normal subjects, suggesting a mixed marasmus-like and kwashiorkor-like pattern of protein-calorie malnutrition. The protein intake was normal, whereas the energy intake tended to be low. Protein intake was significantly correlated with the predialysis serum urea nitrogen. Due to the difficulties in improving oral energy intake and the negative nitrogen balance reported during the days of dialysis therapy, patients were given intravenous supplements of essential or essential and nonessential amino acids for 2 months. The effects of this short-term supplementation were limited.

Response of plasma lipid fractions to the administration of exogenous phospholipids

Plasma lipidic fractions (total lipids, free and total cholesterol, triglycerides, total phospholipids and low density lipoproteins) of 16 hyperlipemic subjects have been followed up over a 4-week period. Intravenous injection of exogenous phospholipids prepared from pig heart resulted in a significant decrease of all the examined lipidic fractions. The possible mechanims of exogenous phospholipids action is discussed.