Nutrition
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Comparative Study
Effects of MCT/LCT and LCT emulsions on plasma lipids and nitrogen retention in streptozotocin-induced diabetic rats receiving total parenteral nutrition.
This study was designed to investigate the effects of emulsions containing medium-chain triacylglycerols (MCT) or long-chain triacylglycerols (LCT) on plasma lipids and nitrogen retention in diabetic rats receiving total parenteral nutrition (TPN). Diabetes was induced in rats by streptozotocin (STZ). Control and diabetic rats were divided into two TPN groups. ⋯ Plasma glucose and TG levels, however, remained higher in diabetic groups than in control groups. No difference in the concentrations of plasma TG, cholesterol, NEFA, beta-hydroxybutyrate or nitrogen retention were observed between the two diabetic groups. These results suggest that MCT/LCT infusion did not lead to hyperketonemia and hypercholesterolemia as compared with LCT infusion, and had no beneficial effect on nitrogen retention in rats with STZ-induced diabetes under the present experimental conditions.
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Sixty male Sprague-Dawley rats were randomized to receive parenteral nutrition (PN) only; PN plus continuous infusion of Escherichia coli 026:B6 lipopolysaccharide (PN + LPS) at 6 mg.kg-1.d-1; or PN plus LPS plus a continuous infusion of the alpha-adrenergic antagonist phentolamine (PN + LPS + PHEN) at 5 mg.kg-1.d-1 or 20 mg.kg-1.d-1 for 48 h. All animals received isocaloric, isonitrogenous PN. LPS significantly lowered nitrogen balance (mmol/48 h) from PN control; however, addition of PHEN substantially worsened nitrogen balance compared with LPS (14.2 +/- 3, 2.4 +/- 5.2, -1.6 +/- 4.5, -0.8 +/- 5.4, for the PN, PN + LPS, PN + LPS + PHEN5 and PN + LPS + PHEN20 groups, respectively; P < 0.0001). ⋯ The high-dose PHEN resulted in 82 +/- 9% blockade. To ascertain if any beneficial effect upon body protein loss is achieved during severe stress, 30 rats were given PN + LPS at 12 mg.kg-1.d-1 or PN + LPS12 + PHEN20. These data showed similar changes in nitrogen balance and 3-methylhistidine/creatinine with the use of PHEN during severe endotoxemia. alpha-adrenergic antagonism with PHEN worsens body protein loss as measured by nitrogen balance and 3-methylhistidine/creatinine in PN-fed endotoxemic rats.
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Review
The route of nutritional support in the critically ill: physiological and economical considerations.
Although it generally is accepted that early enteral nutrition is of benefit to critically ill patients, there is little evidence to support this assertion. Nevertheless, enteral nutrition has many advantages over total parenteral nutrition (TPN), the latter being associated with several complications. Animal studies have shown that injury and infection can lead to gut atrophy and increased mucosal permeability. ⋯ There are few absolute contraindications to early enteral feeding and with motivated staff, the use of prokinetics, and the availability of jejunal feeding tubes, the majority of intensive care patients can be fed enterally. Enteral feeding is more cost effective than TPN, but TPN remains a common therapeutic intervention in the intensive care unit and represents a significant burden on health care budgets. Nutrition support teams have led to savings, particularly by identifying patients who have been inappropriately prescribed TPN and also by preventing excessive enteral feeding.
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Recent findings suggest that many human fetuses have to adapt to a limited supply of nutrients and in doing so they permanently change their physiology and metabolism. These "programmed" changes may be the origins of a number of diseases in later life, including coronary heart disease and the related disorders stroke, diabetes, and hypertension.