Biomedical subjects

J Riby

Publications and source records attributed to J Riby.

3 recordsLinked to original sources

PubMed1991

Intestinal absorption of fructose in the rat.

The objective of this study was to investigate the mechanisms involved in intestinal absorption of fructose. The results indicate that adult rats readily absorbed 0.4 g of fructose, an amount equivalent to 1.4-1.6 g fructose/kg body wt. Acute malabsorption of fructose occurred with doses greater than 0.6 g (2.1-2.4 g/kg body wt). Continued exposure to dietary fructose resulted in a decrease in the evidence of colonic fermentation. Glucose or galactose administered with fructose enhanced the absorption of fructose. The greatest absorption was observed when equal amounts of fructose and glucose were given simultaneously. If glucose was ingested as a polymer (starch or dextrin), the stimulatory effect was dependent on the digestibility of the polymer. Sucrose given with the fructose and glucose diminished the absorption of fructose. Acarbazone, a specific inhibitor of alpha-glucosidases, including sucrase, also inhibited the facilitating effect of glucose and galactose in absorption of fructose. These results give evidence for joint absorption of the two monosaccharides, fructose and glucose.

Acarbose↗

PubMed1990

Renal trehalase: function and development.

1. Following injection of trehalose into the bloodstream, no trehalose was found in urine of rabbits until the concentration of trehalose in blood exceeded 0.6 mg/ml. 2. Absence of trehalose in urine of the rabbit when the concentration of the sugar in blood is elevated supports the hypothesis that renal trehalase functions as a digestive enzyme in kidney. 3. The rat does not possess renal trehalase, and excretion of trehalose was in direct relation to the concentration of trehalose in blood. 4. There are differences in expression of the disaccharidases in kidney and intestine although they share many structural and enzymatic characteristics.

Animals↗

PubMed1985

Rat intestinal brush border membrane trehalase: some properties of the purified enzyme.

Rat intestinal brush border trehalase (EC 3.2.1.28) solubilized by Triton X-100 or Emulphogen BC 720 has been purified almost to homogeneity in a five steps procedure including DEAE cellulose, Sephadex G-200, preparative flat bed electrofocusing and hydroxylapatite. The apparent molecular weight was estimated to be about 65,500 daltons by mannitol density gradient ultracentrifugation. The optimum pH of the enzyme was between 5.5 and 5.7 in phosphate, maleate or citrate buffers. The apparent Km for trehalose was found to be 10 mM in maleate buffer pH 6.0. The isoelectric point was 4.9. Tris, P-aminophenylglucoside, sucrose and maltose are fully competitive inhibitors with Kis of 2.2, 1.8, 7.7 and 170 mM, respectively. The inhibition by Phloridzin appeared to be of the mixed type with a Ki of 1.7 mM. Trehalase is heat stable up to 50 degrees C and the activation energy is 10.96 kcal/mol. Schiff's staining on polyacrylamide gel and interaction with Con-A-Sepharose indicate that rat trehalase is a glycoprotein.

Animals↗