Vitamin C supplementation of total parenteral nutrition formulas.

The effect of a wide range of daily vitamin C intake (350-2250 mg, mean 975 mg) on the serum and urine vitamin C levels was studied in 20 adult hospitalized patients receiving total parenteral nutrition for a period greater than 15 days. Serum vitamin C levels increased with vitamin C administration, but remained within the normal range. Urine vitamin C levels were above normal during total parenteral nutrition in all but one patient. A positive vitamin C "balance" was achieved in all patients. The vitamin C intake positively correlated with the vitamin C urine concentration and vitamin C "balance." Maximal vitamin C retention was 800 mg/day. It is concluded that administration of vitamin C in doses greater than 1000 mg/day is unjustified in those patients receiving total parenteral nutrition who are not hypermetabolic.

A new method for long-term intravenous alimentation in unrestrained rats.

Existing equipment for long-term iv alimentation in small laboratory animals is somewhat cumbersome and quite costly. Although a one-time expense, the cost of this equipment may not be economically viable for many researchers. Herein we present a novel method for long-term iv alimentation in unrestrained rats that is practical, inexpensive, and easily assembled from readily available materials. This new "proxy" set was tested and compared with the standard swivel assembly set. Statistical analysis showed no difference in measured parameters in rats infused by either method. However, the cost of the new set (excluding pump) was almost 90 times less than its commercially available counterpart. This self-constructed approach should bring small animal research within the economic means of most investigators.

Comparative study of clearance of 10% and 20% fat emulsion.

The rate of fat emulsion clearance from the blood of 10 healthy adult male volunteers administered 0.1 gram of fat per kilogram body weight as 10% or 20% safflower oil emulsion (Liposyn) was studied. The subjects were hospitalized for 2 days and each was given the predetermined amount of one of the two fat emulsions (10% or 20%) by rapid injection into a peripheral vein and the rate of clearance of the emulsion determined over a 60-minute period, beginning when half of the emulsion had been injected. There was no significant difference in the clearance rate between the two emulsions. It is concluded that 20% fat emulsion is a safe as 10% fat emulsion for use in intravenous nutritional support.

Cholesterol: an antidiarrheal agent in rats with short-bowel syndrome fed elemental diets.

Studies show that bile acids and long-chain fatty acids are responsible for diarrhea in certain malabsorption syndromes. Recent reports indicate that substances such as dietary cholesterol, when moderately consumed, can reduce bile-induced excessive mucosal fluid and electrolyte output. This study explores the antidiarrheal effect and dosage of dietary cholesterol in rats following massive bowel resection, co-fed elemental diet. Thirty-five male Sprague-Dawley rats weighing 248-253 g underwent 75% resection of the small bowel and were fed ad libitum for 21 days with 1 of 5 diets (n = 7) of Vivonex HN, supplemented by 0, 2.5, 5, 10 or 15 mM cholesterol/1,000 g of the powdered elemental diet. Parameters measured included daily food and water consumption, daily changes in weight, volume of excrement and stool consistency graded by the same individual (water, semiformed or formed). It was found that 5 mM dietary cholesterol in 1,000 g of the elemental diet produced the most formed stool and significantly improved weight gain in rats with short-bowel syndrome.

A new method for long-term intravenous alimentation in unrestrained rats.

A new technique for continuous long term intravenous alimentation in unrestrained rats has been developed. The model involves the use of the intravenous tubing set which was constructed from the barrel of a 1 ml syringe-cylinder with flanges sutured to the rat's skin. After inserting the silicone catheter into the jugular vein the free end was exited at the intraauricular area and passed through the intravenous tubing set. The tubing was then connected with a silk suture to the top of the cage. This prohibits twisting of the system and allows unrestrained movement of the rat in the cage with a rotation of 6-8 turns in either direction. The metabolic cage was constructed from an inverted 4-liter glass jug with the base removed. A floor and root were fashioned from coarse wire screen. Urine and feces were easily separated and collected through the neck of the jug. This new "proxy" set was tested and compared with the standard swivel assembly parameters in rats infused by either method. However, the cost of the new set (excluding pump) was almost 90 times less than its commercially available counterpart. This self constructed approach should bring small animal research within the economic means of the most investigators.

Efficacy of enteral diets in the prevention of stress-induced gastric erosions in rats.

This study compares the prophylactic effects of two different diets and routes of feeding on restraint stress-induced gastric erosions in the rat. Thirty male Sprague-Dawley rats were food-deprived and immobilized for 24 hours using a steel wire mesh. A small silicone tube was placed into either the proximal jejunum or the stomach via a laparotomy. There were three groups of ten rats (five jejunum-fed, five stomach-fed), receiving infusions (50 ml/24 h) of: (A) normal saline; (B) free amino acids (Vivonex HN, Norwich Eaton Pharmaceuticals) (60 cal and 0.318 G nitrogen); or (C) a peptide diet, with the nitrogen source as lactalbumin hydrolysate, otherwise identical to B. Gastric acidity was measured every 4 hours. At 24 hours, blood was collected and serum gastrin levels determined. The animals were then sacrificed and the stomachs examined. The results were analyzed using one-way analysis of variance. Fewer gastric erosions and lower serum gastrin levels and gastric acidity were found in animals fed diets B and C, versus animals fed normal saline (p less than 0.05). There was no difference between groups B and C. Our results also show that enteral diets using the jejunal route are better than those using the gastric route in reducing the incidence of stress-induced gastric erosions in rats.