Search PubMed⌕ Search

Biomedical subjects

J M Bengoa

Publications and source records attributed to J M Bengoa.

At least 37 records · Page 2Linked to original sources
PubMed1985

Urinary C-peptide measurements in patients receiving continuous and cyclic total parenteral nutrition.

Urinary C-peptide excretion has been found to be an accurate index of insulin secretion under a variety of physiologic conditions, such as acute starvation and exercise, and after oral and intravenous glucose administration. We investigated urinary C-peptide responses in a group of patients who were receiving all of their nutrient intake by intravenous administration. In these patients receiving total parenteral nutrition (TPN), we were able to monitor changes in insulin secretion when the same nutrients were infused at different rates, for example, during cyclic vs. continuous TPN administration, and to observe changes in the insulin secretory response as the pattern of nutrient delivery was altered in the same individual. We found that increasing the TPN infusion rate by 50% during cyclic TPN caused a 65% increase in serum insulin levels over levels observed during continuous TPN administration (93 vs. 60 microU/ml), whereas a 100% increase in the cyclic TPN infusion rate above the continuous TPN rate increased insulin levels by 147% (147 vs. 60 microU/ml). The molar ratio of insulin to C-peptide was increased by increasing rates of TPN infusion, from 0.116 during fasting periods to 0.151 during maximum rates of TPN administration. An additional finding of this study is that 24-hour insulin secretion, estimated by urinary C-peptide measurements, was equivalent in all treatments regardless of the pattern of insulin response elicited.

Adult↗
PubMed1984

Hepatic vitamin D 25-hydroxylase inhibition by cimetidine and isoniazid.

Cimetidine interaction with cytochrome P-450 may reduce binding affinity of some drugs, causing reduced metabolism of substrates such as diazepam and warfarin. Isoniazid also inhibits hepatic mixed function oxidase activity and has been reported to depress circulatory levels of hydroxylated vitamin D metabolites. Because hepatic vitamin D 25-hydroxylase is considered to be a cytochrome P-450-dependent enzyme, we examined the effect of cimetidine and isoniazid on hepatic vitamin D 25-hydroxylase activity in vitro in the rat. The assay system employed whole liver homogenates from rats deficient in vitamin D and chromatographic separation of radiolabeled substrate and product. Cimetidine and isoniazid were incubated with liver homogenates prior to the addition of 12 nmol/L final concentration of tritiated vitamin D. In addition, assays were performed in rats deficient in vitamin D given cimetidine or isoniazid 1 hour before sacrifice. Both cimetidine and isoniazid inhibited vitamin D 25-hydroxylase activity in vitro. Vitamin D 25-hydroxylase activity was depressed to 75%, 65%, and 55% of control values by cimetidine at 3, 6, and 10 mmol/L concentrations, respectively, and to 81%, 53%, and 35% by isoniazid at 1, 5, and 10 mmol/L. In vivo intraperitoneal administration of 120 mg/kg cimetidine depressed vitamin D 25-hydroxylase activity by 22%, and the same dose of isoniazid inhibited activity by 26%. The effect of long-term cimetidine therapy on vitamin D metabolism requires further evaluation.

Animals↗
PubMed1983

Amino acid-induced hypercalciuria in patients on total parenteral nutrition.

Ingestion of protein is known to increase urinary calcium excretion. By studying the effect of intravenous amino acid infusion on calcium excretion, the variables of diets and intestinal absorption are avoided. Five patients on total parenteral nutrition with otherwise constant nutrient infusions containing 240 mg of calcium were randomized to two different levels of amino acid infusion. On 1 g/kg ideal body weight amino acid infusion, two patients excreted more than 240 mg of calcium in the urine, while on 2 g/kg ideal body weight amino acid infusion all five patients lost more calcium in urine than was infused. Mean urinary calcium excretion was increased from 287 to 455 mg/day. On the higher amino acid dose, mean glomerular filtration rate increased from 102 to 143 ml/min. There was no effect of amino acid dose on serum calcium, ionized calcium, parathyroid hormone, and 25 (OH) vitamin D. Calcium excretion corrected for the glomerular filtration rate was increased at the higher amino acid dose, indicating a decrease in renal calcium reabsorption. Daily urinary excretion of sulfate, ammonia, and titratable acidity were increased during the high amino acid infusion. Hypercalciuria induced by high levels of amino acid infusion during total parenteral nutrition may contribute to the development of metabolic bone disease.

Adult↗
PubMed1976

Nutritional situation in the world.

The paper describes the international nutrition problem, with references to previous crisis in the world. It is stated that the present situation cannot be compared to the historical famines in the past. The causes and magnitude of the problem are quite different. The information available on the nutritional situation in the world at present is scanty, erratic and contradictory. The criteria used for such evaluation is not uniform, and this is the reason of the differences in the estimation of the magnitude of the problem. According to the analysis of 101 surveys conducted in 59 developing countries during the last 10 years, in which more than 260,000 children below 5 years were examined the percentage of cases of severe forms of malnutrition was of 2.3% and of moderate forms of 18.8%. However there are some areas where severe forms represent 10 or 20% of children examined. Taking only the most representative surveys (25 out of 59) a rough estimation of the total number of malnoursihed children in developing countries gives the figure of 10 millions of severe forms and 90 millions of moderate forms. The paper makes references to mortality trends in developing countries compared with the trends observed in developed countries. It is the view of the author that the recent dramatic decline on mortality in developing countries is due more to public health action, particularly the existence of new drugs, than to any significant improvement in the standard of living, including nutrition. A distinction is made on the differences between the biological needs of nutrients and the social satisfaction produced by food intake. In fact the biological needs are much less than the average consumption of the affluent society. It is suggested that in order to raise the standards of nutrition in developing countries it would perhaps be necessary to moderate the excessive consumption among other things, of proteins of animal origin in developed countries. Finally the author strongly recommend to intensify the action on nutrition at international, national and family level.

Africa↗