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Biomedical subjects

S L Ink

Publications and source records attributed to S L Ink.

6 recordsLinked to original sources
PubMed1990

Dose response to a dietary oat bran fraction in cholesterol-fed rats.

The two objectives of this research were to improve the cholesterol-fed rat as a model for evaluating the hypocholesterolemic potential of foods and to determine the relationship between serum and liver lipid levels in the cholesterol-fed rat and the ingestion of nine levels of a high fiber oat flour (HFOF) derived from oat bran. Ingestion of 0.2% cholic acid, sodium cholate or sodium taurocholate with 1% cholesterol (CH) significantly elevated serum and liver CH, liver triglycerides and liver weight compared to those values in control rats fed diets not containing CH and bile acids; 0.05 and 0.1% cholic acid with 1% CH were also effective. Ingestion of increasing amounts of HFOF, containing 0-10% dietary fiber, by rats made hypercholesterolemic with 1% CH and 0.1% cholic acid in the diet produced a significant inverse relationship between serum and liver cholesterol levels and HFOF intake; r = 0.48, p less than 0.0001 for serum CH and r = 0.55, p less than 0.0001 for liver CH. Because of the similarities in the responses of humans and of the cholesterol-fed rat to oat fiber ingestion, this dose-response relationship in the rat model suggests that larger intakes of soluble oat fiber sources may be accompanied by greater reduction in serum CH levels in humans.

Animals↗
PubMed1988

Oat fiber: composition versus physiological function in rats.

The effect of processing on the ability of oat fiber to lower plasma and liver cholesterol concentrations in rats was studied. Male Sprague-Dawley rats were fed diets containing 6% dietary fiber as cellulose, oat bran, high fiber oat flour or one of four processed high fiber oat flours for 3 wk. All diets also contained 1.0% cholesterol and 0.2% cholic acid. At the conclusion plasma and liver concentrations of cholesterol and triglycerides were measured. All of the oat products significantly lowered plasma and liver cholesterol without depressing food intake or weight gain. As little as 4% dietary fiber in a processed oat flour significantly lowered cholesterol concentrations. Detailed fiber analysis of all of the oat fiber products revealed that processing increased the proportion of the total fiber that was soluble. The proportions recovered as total beta-glucans and total neutral sugars also increased, in part because the proportion recovered as Klason lignin decreased in all of the processed oat flours except the one prepared by a high pressure extrusion process.

Animals↗
PubMed1987

Comparison of pteroylpolyglutamate hydrolase (folate conjugase) from porcine and human intestinal brush border membrane.

1. A comparative study of pteroylpolygluatamte hydrolase (folate conjugase) of brush border membrane vesicles from human and porcine intestine was conducted. 2. The enrichment of conjugase activity during membrane isolation was 5-fold greater for the human than the pig. 3. Porcine and human conjugases exhibited similar Km values and could completely hydrolyze pteroyltriglutamate (PteGlu3) to PteGlu1 via an exohydrolytic process. 4. Pteroic acid, PteGlu1 and anionic polysaccharides did not inhibit human or porcine conjugase. 5. Apparent mol. wts for detergent-enzyme complexes were 237,000 (pig) and greater than 500,000 (human). 6. These results indicate similar kinetic properties and mode of action but differences in physical behavior between the intestinal brush border folate conjugases of human and pig.

Animals↗
PubMed1984

Effect of binding to hemoglobin and albumin on pyridoxal transport and metabolism.

Scatchard plot analysis indicated that pyridoxal binds to hemoglobin more than twice as tightly as it does to serum albumin. Comparison of the formation constants for hemoglobin and albumin, using standard competitive binding equations, indicated that the distribution ratio for pyridoxal between erythrocytes and plasma should be 6.5:1. This distribution was approximately the same as that observed when pyridoxal was incubated with whole human blood, suggesting that these two proteins are the primary determinants of the pyridoxal distribution in whole blood. With in situ perfused rat liver the uptake of [3H] pyridoxal from the perfusate was reduced by the inclusion of erythrocytes in the perfusate. This was reflected in the decreased production of 4-pyridoxic acid by the perfused liver from 3.8% to 1.2% of the dose by the addition of erythrocytes to the perfusate. The major labeled metabolites found in the liver were pyridoxal phosphate, pyridoxamine phosphate, and 4-pyridoxic acid for both types of perfusion. In intact animals, reduction of the erythrocytes concentrations to hematocrits of 30-40% increased the recovery in the urine of 3H from administered [3H] pyridoxal from control values of 27-35% to 40-50% of the dose within 48 h. Half of the label in urinary metabolites was in 4-pyridoxic acid.

Animals↗
PubMed1982

The binding of pyridoxal to hemoglobin.

Concentrative uptake of pyridoxal by human erythrocytes has been investigated using a rapid mixing technique with 3H-labeled pyridoxal. A nonsaturable, initial influx of [3H]pyridoxal into the erythrocyte indicated passive diffusion. Since pyridoxal will form Schiff bases reversibly with amino acids, the possibility of binding to intracellular proteins was examined. Exposure of erythrocytes to pyridoxal followed by NaBH4 reduction, resulted in a stable pyridoxyl-protein complex. The binding site for pyridoxal was found to be on the alpha chain of oxyhemoglobin, as determined by ion exchange chromatography and amino acid analysis. Separation of the tryptic peptides from the [3H]pyridoxyl-alpha chain on Dowex 50 and analysis of the [3H] pyridoxal peptide showed that the binding site of pyridoxal was the NH2-terminal valine. Pyridoxal was also found to bind to the alpha chain of nonoxygenated hemoglobin. The rate of pyridoxyl-hemoglobin formation in a cell-free system provided additional evidence in support of the suggestion that concentrative uptake of pyridoxal by human erythrocytes is due to intracellular binding of pyridoxal to hemoglobin. Pyridoxal phosphate and glucose, which also bind to the NH2-terminal valine, did not reduce the accumulation of pyridoxal in the erythrocyte.

Amino Acids↗