Reference

Guaran effect on rat intestinal absorption

Guaran effect on rat intestinal absorption. A perfusion study. Elsenhans, Bernd; Zenker, Dieter; Caspary, Wolfgang F.; Blume, Roland (Dep. Med., Univ. Goettingen, Goettingen D-3400, Fed. Rep. Ger.). Gastroenterology, 86(4), 645-53 (English) 1984. CODEN: GASTAB. ISSN: 0016-5085. DOCUMENT TYPE: Journal CA Section: 18 (Animal Nutrition) Section cross-reference(s): 4, 13 The direct action of guaran [9000-30-0] on small intestinal absorption was evaluated by a single-pass perfusion technique. Guaran in the perfusate (1-7 g/L) inhibited small intestinal absorption of actively transported compds., such as a-methyl-D-glucoside [97-30-3], cycloleucine [52-52-8], and taurocholate [81-24-3], and also of the passively permeating solutes 2-deoxy-D-glucose [154-17-6] and urea [57-13-6]. Viscosity-related inhibition by guaran depended on the rate of perfusion and was only detectable at perfusion rates <0.4-0.5 mL/min. Higher perfusion rates abolished and even reversed the inhibitory effect. The obsd. alterations of absorption rates caused by guaran were completely reversible after switching to a guaran-free perfusate. The concn.-dependent absorption of D-glucose [50-99-7] and a-methyl-D-glucoside at perfusion rates of 0.4 and 0.2 mL/min, resp., revealed an increase in the transport const. and essentially unaltered maximal transport capacity in the presence of guaran. Addnl., net water absorption changed to secretion upon addn. of guaran. When pectin [9000-69-5] and carrageenan [9000-07-1] were used in solns. of comparable viscosity, their effect was similar to that of guaran. The results suggest a general mechanism by which sol., viscosity-enhancing polysaccharides influence the intestinal absorption of nutrients. The most likely explanation appears to be an increase in the unstirred layer resistance to diffusion. Under the exptl. conditions used, this occurred at low perfusion rates, but was increasingly counteracted by raising the rate of perfusion.

Insulin action on Escherichia coli

Insulin action on Escherichia coli. Regulation of the adenylate cyclase and phosphotransferase enzymes. Abou-Sabe, M.; Reilly, T. (Dep. Microbiol., Rutgers, State Univ., New Brunswick, N. J., USA). Biochim. Biophys. Acta, 542(3), 442-55 (English) 1978. CODEN: BBACAQ. ISSN: 0006-3002. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Insulin [9004-10-8] action on E. coli was studied using wild type E. coli B/r and K12 strains and a no. of phosphoenolpyruvate phosphotransferase [9055-38-3] mutants. In vivo, the effects of insulin on the differential rate of tryptophanase [9024-00-4] synthesis, the rate of a-methylglucoside [97-30-3] uptake and the rate of growth on glucose [50-99-7] were detd. in E. coli B/r. In vitro, the effect of insulin on the adenylate cyclase [9012-42-4] and the phosphotransferase activities was detd. using toluenized cell prepns. of E. coli B/r, E. coli K12 and phosphotransferase mutant strains. The specificity of insulin action on E. coli was detd. using glucagon, vasopressin, and somatotropin as well as insulin antisera. Results showed the specific action of insulin on E. coli, inhibiting tryptophanase induction and adenylate cyclase activity, while stimulating growth on glucose and uptake and phosphorylation of a-methylglucoside.