Effect of intravenously administered fat on serum insulin levels

Whole-body protein metabolism in cancer-bearing patients. Effect of total parenteral nutrition and associated serum insulin response

Aggressive nutritional support of the cancer patient undergoing treatment has become widespread standard practice. In order to evaluate the effect of total parenteral nutrition (TPN) on protein metabolism, 11 patients with localized squamous cell carcinoma of the distal esophagus were studied in the postabsorptive state and again after 2 weeks of TPN. After two weeks of TPN, these cancer patients demonstrated a significant increase in body weight associated with positive nitrogen balance and an insignificant increase in total body potassium (determined by whole body 40K scanning), a measure of lean body mass. Serum transferrin, ceruloplasmin, and total protein did not change significantly, whereas serum albumin decreased significantly (3.5 +/- 0.1 to 3.1 +/- 0.1 g dl-1). Evaluation of whole-body protein kinetics by constant infusion of 15N-glycine demonstrated a significant increase in protein flux (2.79 +/- 0.20 to 4.02 +/- 0.33 g protein kg-1 day-1). In the group as a whole, protein synthesis increased and catabolism decreased, but not significantly. Skeletal muscle protein catabolism, as measured by the rate of excretion of urinary 3-methylhistidine (mumol kg-1 day-1) decreased significantly after 2 weeks of TPN (2.5 +/- 0.1 to 1.9 +/- 0.2). A change from basal to stimulated (TPN) serum insulin level of 40 to 120 microU/ml was found to be associated with optimal changes in protein synthesis and skeletal muscle catabolism. Five patients fell within this optimal range of serum insulin, and demonstrated a significant increase in the rate of wholebody protein synthesis (2.13 +/- 0.35 to 3.56 +/- 0.45 g protein kg-1 day-1) with an insignificant increase in whole-body protein catabolism (2.74 +/- 0.42 to 3.16 +/- 0.43), and a significant decrease in urinary 3-methylhistidine excretion (2.50 +/- 0.35 to 1.53 +/- 0.24) after 2 weeks of TPN. It is concluded that optimum nutritional support with TPN is beneficial to the cancer patients' protein economy by stimulating whole body protein synthesis while decreasing skeletal muscle protein catabolism. It is also concluded that there exists a range of serum insulin in which whole-body protein synthesis and catabolism are optimized.

The quantitative transperitoneal absorption of a fat emulsion: implications for intraperitoneal nutrition

Intraperitoneal (IP) administration of nutrients would be an attractive alternative to intravenous nutrition since it eliminates intravascular complications. If glucose alone were used as the nonprotein calorie source, associated fluid shifts might not be well tolerated by the patient. A fat emulsion does not have osmotic properties and thus might be incorporated into a program of IP nutrition as a calorie source. Transperitoneal absorption of a commercial fat emulsion (Liposyn 10%, Abbott Laboratories, N Chicago, IL) was studied in 12 beagle puppies divided into two groups. One group received 2.5 gm/kg of fat and the other group received a similar volume of 3.5% crystalline amino acids and 5% glucose in one IP dose. In the first group, the serum triglyceride (TG) increased three fold from 61 +/- 25 mg% to 185 +/- 61 mg% at 15 minutes and then decreased slowly while remaining significantly elevated (p less than 0.05) at 4 hours. 1.94 +/- 0.20 gm/kg of TG were absorbed from the peritoneal cavity over 4 hours. Concommitant IP administration of amino acids and glucose did not affect that absorption. Radiolabeled amino acids and glucose instilled IP were demonstrated in the blood immediately after administration and their absorption was not affected by the presence of a fat emulsion. Plasma free fatty acids showed a small increase at 4 hours (from 0.32 +/- 0.09 mEq/L to 0.59 +/- 0.22 mEq/L). Animals receiving no IP fat showed no change in serum TG. Serum glucose rose in both groups and serum cholesterol showed no changes in either group. Peritoneal fluid accumulation 4 hours after IP fat administration was minimal at 12.7 +/- 6.4 mL/kg. This study shows that a fat emulsion can be quantitatively absorbed from the peritoneal cavity over four hours and that IP nutrition may be feasible.

Clinical and metabolic consequences of two regimens of total parenteral nutrition in the newborn

The clinical and metabolic effects of two regimens of total parenteral nutrition delivering the same amino-acid (2·8 g/kig per 24 h), fat (4·8 g/kg per 24 h), and glucose (12 g/kg per 24 h) load over 24 hours were studied. The regimens differed in the distribution of the infusate during the 24-hour period. With the continuous regimen (7 infants) all nutrients were infused together at a constant rate, whereas with the sequential regimen (9 infants) the daily doses of Vamin/glucose and Intralipid were infused together, followed by the glucose dose. The infants studied had a mean birthweight of 2·8 kg and mean gestational age of 37·9 weeks. Blood levels of glucose, lactate, pyruvate, 3-hydroxybutyrate, acetoacetate, alanine, glycerol, and insulin were measured longitudinally from day 1 to day 21 of total parenteral nutrition. The 7 infants who received the continuous regimen had blood metabolite levels comparable with those of infants fed enterally, with minor fluctuations. Insulin levels were higher than in enterally-fed infants. The 9 infants who received the sequential regimen had wide fluctuations in alanine, glycerol, insulin, 3-hydroxybutyrate, and acetoacetate levels with high peak levels of ketones at the end of the Vamin/glucose and Intralipid infusion, falling to low levels at the end of the 24-hour cycle. There was a gradual reduction in the peak ketone levels from day 6-8 to day 18-21. Clinically unsuspected hypoglycaemia occurred on 6 occasions in each group of infants. There was no significant difference in the incidence of jaundice or infection between the two groups, and the weight velocity during total parenteral nutrition was similar. Wide fluctuations in the infusion rates of individual substrates should be avoided during total parenteral nutrition in the newborn.

Acute hemodynamic effects of intravenous fat emulsion in dogs

An intravenous infusion of Intralipid-10% was observed to exert a negative inotropic effect on left ventricular performance in a canine isovolumetric left heart preparation. There was no effect on diastolic compliance, however. Intravenous fat emulsion also produced significant decreases in systemic vascular resistance. The mechanism of these actions has not been elucidated, but it is postulated that free fatty acid (FFA) components or their metabolites directly affect the contractile properties of both myocardium and smooth muscle. These results suggest that until suitable clinical studies can be obtained, caution should be exercised in administering intravenous fat emulsions, particularly at maximum rates of infusion or in conjunction with sodium heparin in patients with known cardiac dysfunction.

[Metabolic effect of a parenterally administered fat emulsion with middle-chain triglycerides in healthy men]

Within 3 hours, 10 healthy male volunteers were infused 500 ml of a 5 percent emulsion in which 25 percent of the fat proportion had been replaced by MCT-fats. As expected, the ketone body concentration in the blood rose, while pyruvate remained constant and lactate dropped. The results show that, basically, a MCT-containing fat infusion is suited for parenteral nutrition and, because of their specific properties, medium chain triglycerides may be used as rapid energy donators.