PubMed Health⌕ Search

Biomedical subjects

N F Yang

Publications and source records attributed to N F Yang.

14 recordsLinked to original sources
PubMed1996

Alanyl-glutamine preserves hepatic glutathione stores after 5-FU treatment.

Glutathione (GSH) is a major antioxidant that protects tissues from free radical injury. 5-fluorouracil (5-FU) considered the most active antineoplastic agent in the treatment of advanced gastrointestinal malignancies, causes hepatic GSH depletion. Glutamine (GLN) augments host defenses and may be important in GSH synthesis. We hypothesized that alanyl-glutamine (ALA-GLN) may protect liver cells from oxidant injury, like GLN, by increasing hepatic GSH stores. Two rat groups received standard parenteral nutrition (STD) supplemented with or without ALA-GLN for 7 days. After the antineoplastic agent 5-FU was injected, the concentration measurements were significantly different in ALA-GLN group compared with STD animals for serum GLN (687.3 +/- 49.8 vs. 504.9 +/- 38.6 uMol/L, P < 0.05), serum GSH (14.37 +/- 5.16 vs. 7.08 +/- 3.16 uMol/L, P < 0.01) and in liver GSH content (6.86 +/-2.46 vs. 4.38 +/-1.63 uMol/g liver tissue, P < 0.05). Rats in ALA-GLN group had lower elevations in hepatic enzymes induced by 5-FU. The experiment demonstrated that the supplemented nutrition ALA-GLN, like glutamine, protected the liver function and improved survival during 5-FU treatment by increasing GSH biosynthesis and by preserving the GSH stores of hepatic tissue.

Journal Article↗
PubMed1993

A comparison of medium-chain and long-chain triglycerides in surgical patients.

Available lipid emulsions made from soybean or safflower oil are classified as long-chain triglycerides (LCT). In contrast, medium-chain triglyceride (MCT) emulsions have different physical properties and are metabolized by other biochemical pathways. To compare the differences between these two fat emulsions, the authors studied 12 surgical patients and 6 volunteers. These subjects were randomly assigned to receive parenteral nutrition with MCT or LCT emulsion. Measurement of arterial and venous concentration differences across the forearm demonstrated that muscle utilization was significantly improved with MCT administration. There was also a trend toward improved nitrogen balance in the MCT group, and less weight loss in the postoperative period also was observed in this group. During the fat clearance test, the serum ketone concentrations were significantly higher in the MCT than the LCT group. The improvement in nitrogen retention may be associated with increasing ketone and insulin levels. Fat emulsions containing 50% MCT are safe for use in parenteral nutrition and may provide an alternate fuel that improves protein metabolism.

Drug Combinations↗
PubMed1989

Low-dose growth hormone and hypocaloric nutrition attenuate the protein-catabolic response after major operation.

To determine the effects of low-dose recombinant human growth hormone (GH) and hypocaloric nutrition on postoperative convalescence, we performed a placebo-controlled randomized double-blind trial in 18 patients after elective gastrectomy or colectomy. The subjects received parenteral nutrition containing 20 calories/kg per day and 1 g protein/kg per day. Daily injections of drug or placebo were given during the first postoperative week. The nine control subjects lost 3.3 kg (5.9% of preoperative weight) and had a cumulative nitrogen loss of 32.6 +/- 4.2 g nitrogen at eight days. The patients receiving GH lost significantly less weight (1.3 kg) and nitrogen loss was 7.1 +/- 3.1 g at eight days (p less than 0.001). Kinetic studies demonstrated that the anabolic effects of GH were associated with increased protein synthesis, and amino acid flux studies across the forearm revealed increased uptake of amino acid nitrogen in the GH-treated patients. Body compositional analysis revealed that the patients receiving GH maintained their lean body mass despite the major surgical procedure. Analysis of hand grip force showed a 10% loss of strength in the control subjects; with GH the patients maintained their grip force throughout the postoperative period. We conclude that the postoperative catabolic response can be modified with GH and hypocaloric nutrition. These metabolic and physiologic effects should now be studied in a larger number of patients to determine if this approach can reduce morbidity, mortality, and length of hospital stay for surgical patients.

Amino Acids↗
PubMedDate not supplied

Body composition in Chinese subjects: comparison with data from North America.

A multiple tracer dilution method measuring total body water, extracellular water, plasma volume, and red cell volume was used to study body composition. Healthy Chinese subjects were compared to a group of Chinese patients with various newly diagnosed gastrointestinal disorders scheduled for elective operation. Compositional data obtained from these groups showed no significant differences in compartmentalization, suggesting absence of major changes during the early stages of certain gastrointestinal diseases. In addition, healthy Chinese subjects were compared to a group of healthy Americans previously evaluated by similar dilutional methods. In males, body weight (kg) differed considerably (Chinese = 62.1 +/- 2.0 versus American = 72.5 +/- 4.1, p less than 0.02) and could be explained by alterations in body fat (Chinese = 12.4 +/- 1.3 versus American = 19.2 +/- 2.2, p less than 0.02) and extracellular water (Chinese = 14.4 +/- 0.5 versus American = 16.8 +/- 0.8, p less than 0.02). Functional tissue ("body cell mass") was similar in the 2 groups which suggested that Chinese have comparable body composition without an additional fat burden. The multiple tracer technique using deuterium oxide, sodium bromide, Evans dye, and Cr51 for body compositional assessment is accurate but expensive and laborious. Therefore, equally precise but more economical bedside methods are needed for routine compositional analysis.

Adult↗
PubMedDate not supplied

Postoperative fall in serum zinc concentrations unaffected by intravenous zinc therapy.

The serum zinc levels and urinary zinc outputs before and after a middle severity operative trauma were investigated. The serum zinc concentration dropped markedly 6 hr after operation in both supplemented and nonsupplemented groups. It gradually returned to near normal without exogenous supplies of zinc. Provision of therapeutic doses of zinc could not prevent the abrupt dip of the serum zinc level. The possible mechanism of such changes are discussed briefly.

Female↗
PubMedDate not supplied

Comparison of parenteral nutrition supplemented with L-glutamine or glutamine dipeptides.

Although glutamine is an important fuel used by the intestinal mucosa and other visceral organs, it is not present in any commercially available parenteral amino acid solution. To compare the effects of L-glutamine with glutamine dipeptides, we studied the effects of each in 8 dogs and 60 Wistar rats. In the dog study, three amino acid solutions were compared: standard commercial amino acid solution (control), alanine-glutamine dipeptide-enriched solution (glutamine 3.4%), and glycine-glutamine dipeptide-enriched solution (glutamine 3.6%). Arterial and venous samples were collected to compare the effects of the three solutions on skeletal muscle amino acid exchange. In the rat study, two studies were undertaken: group 1 rats underwent only central venous catheterization; group 2 rats underwent central venous catheterization and a 50% intestinal resection. Within each group, three different solutions were infused: standard amino acid solution (control), glutamine-enriched (1.5% glutamine) solution, or glutamine dipeptide-enriched (1% glutamine) solution. After 7 days of parenteral nutrition, samples of gut, blood, and muscle were collected for determination of mucosal thickness, villus area, serum amino acid profile, liver and renal function tests, and muscle composition. When glutamine or glutamine-dipeptide solutions were administered, the dogs showed increasing serum glutamine concentrations and enhanced glutamine uptake across the hind leg muscle. Similarly, both groups of rats demonstrated significant differences in serum glutamine levels, nitrogen balance, intestinal mucosa thickness, and villus area. We conclude that both glutamine and glutamine-dipeptide infusions increase serum glutamine concentrations and result in regional tissue effects. Both exerted similar metabolic effects with no apparent complications.

Amino Acids↗