Metabolism: clinical and experimental
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Mean peak plasma glutamate concentrations and area under the plasma glutamate concentration-time curve are much lower in adult humans ingesting monosodium L-glutamate (MSG) in formula than in water. The present study investigated the effects of individual meal components on portal and vena caval plasma glutamate concentration in young pigs administered MSG. Portal vein catheters and gastrojejunal tubes were placed in four young male pigs, and the animals were allowed to recover. ⋯ Mean peak plasma glutamate concentration and area under the plasma glutamate concentration-time curve were significantly lower (P less than 0.05) in both portal and vena caval blood when MSG was administered with metabolizable carbohydrate than when administered in water. Simultaneous ingestion of MSG with nonmetabolizable carbohydrate (beta-cellobiose) or amino acids had no significant effect on either mean peak portal or vena caval plasma glutamate concentration or area under the plasma glutamate concentration-time curves when compared to values observed when MSG was administered alone. The data suggest that metabolizable carbohydrate is the meal component affecting plasma glutamate concentration.
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Surgical stress with inhalation anesthesia is associated with increased circulating catecholamines, hyperglycemia, and impaired insulin secretion. These changes do not occur during surgical stress with spinal anesthesia, suggesting that they are neurally mediated due to pain initiated afferents from the site of tissue trauma. ⋯ In the postoperative period, however, suppressed insulin secretion was found to be correlated with elevated plasma epinephrine concentrations and may, therefore, be mediated by adrenergic mechanisms. Thus, these findings indicate that impaired insulin secretion during surgical stress may have two etiologies--one related to the type of anesthesia used and the other due to adrenomedullary stimulation due to pain.
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Body fat, fat cell size, and fat cell number were determined in a longitudinal study on 16 normal-weight infants during the age period 1-18 mo. The methods used included whole-body counting of 40K for determination of body fat and adipose tissue biopsies. A new method of calculation of body fat in infants is presented. ⋯ From 1 to 12 mo of age the expansion of body fat was explained by and increase in fat cell size, while in the age period 12-18 mo it was mainly due to an increase in fat cell number. At 18 mo lthe fat cell size was the same as in 8-yr-old girls and 22-yr-old women (normal-weight females previously studied). The fat cell number at 18 mo, however, was far below the number at 8 yr of age, as well as the still higher number of the 22-yr-old women.
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Oleic acid emulsions stabilized with albumin were infused into fasted rats. Blood samples taken before and during infusion were analyzed for free fatty acids (FFA), ketone bodies, glucose, and insulin. Turnover rates of FFA and ketone bodies were also determined using constant infusion of radioactive tracers. ⋯ Insulin injected during infusion had little effect on concentrations of FFA or ketone bodies. It was concluded that infusions of oleic acid inhibit adipose tissue lipolysis and increase blood ketone concentrations in intact fasted rats. The injection of insulin does not inhibit ketogenesis when blood FFA levels are maintained by infusion.