Biomedical subjects

F L Shinnick

Publications and source records attributed to F L Shinnick.

9 recordsLinked to original sources

PubMed1990

Simultaneous determination of neutral and amino sugars in biological materials.

A method is described for the simultaneous analysis of nine neutral and three amino sugars. Mixtures of standard sugars and biological samples were acid hydrolyzed with a two step Saeman procedure, neutralized with BaCO3, reduced with sodium borohydride, acidified, evaporated and alditol acetates prepared. Baseline resolution was achieved on a glass-capillary SP-2340 column in ca. 52 min. Reproducibility, response factors and hydrolysis losses were determined. Quantitation was linear over the range of 10-20 micrograms/ml to 2000 micrograms/ml. Conditions were defined for the reproducible quantitation of muramic acid.

Amino Sugars↗

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↗

PubMed1990

Neutral sugar composition and gravimetric yield of plant and bacterial fractions of feces.

Separating dietary fiber from other polysaccharides in digesta and feces is necessary to understand its mechanisms of action. A gravimetric method that separates fecal plant and bacterial matter based on size and density was evaluated and modified to determine the plant and bacterial mass of lyophilized whole and blended rat and human feces. Three screen mech combinations (150 and 75 microns, 150 and 35 microns, 35 microns) were used with rat feces. Filtration of a homogenized rat fecal slurry sequentially through 150- and 35-microns-mesh screens versus 150- and 75-microns-mesh screens decreased the gravimetric recovery of bacteria from congruent to 35 to congruent to 25% of fecal dry weight and increased the plant fraction weight. Neutral sugar composition, determined by gas chromatography of alditol acetates, and bacterial counts of the fractions suggested that the decreased yield of bacterial fraction represented removal of plant material and not a loss of bacteria. Rat excreta contained 29.5% (dry weight) total neutral sugar, 88% of which was recovered in the plant material. Human feces containing wheat bran, fractionated with the 150- and 35-microns-mesh screens, was 21% neutral sugar, congruent to 65% of which was in the plant fraction. The plant fractions had more xylose and arabinose and less glucose than the bacterial fractions. Processing samples in a Waring blender had no adverse effect on the rat or human fecal bacterial counts. The use of this gravimetric method in combination with the sugar analysis of the fractions provided a better measure of plant and bacteria than only gravimetric yield.

Animals↗

PubMed1989

Apparent nutrient absorption and upper gastrointestinal transit with fiber-containing enteral feedings.

Upper gastrointestinal tract function in humans was investigated by studying the acute effects of supplementing enteral feedings with dietary fiber. Serum concentrations of folate, zinc, and glucose were determined at timed intervals for 4 h after ingestion of nutritionally complete liquid meals containing test doses of folate and Zn of two and six times the RDA, respectively, with or without addition of 10 or 15 g of soy polysaccharide fiber. Mouth-to-cecum transit time was determined by measuring breath hydrogen produced from lactulose added to the meals. Both levels of fiber significantly lengthened transit time. Serum folate concentrations were significantly lower from 45 to 150 min after one or both fiber-containing meals relative to the fiber-free meal. Only the higher-fiber meal significantly lowered serum Zn concentrations. This study demonstrated that dietary fiber can decrease apparent nutrient absorption and increase transit time in the upper gastrointestinal tract without affecting apparent glucose absorption.

Adult↗

PubMed1988

Soluble oat fiber tends to normalize lipoprotein composition in cholesterol-fed rats.

The effect of oat fiber on VLDL, LDL and HDL composition was investigated by feeding male Sprague-Dawley rats diets containing 1.0% cholesterol and 0.2% cholic acid, and 6% dietary fiber from oat bran, high-fiber oat flour or a processed oat product for 20 d. Compared to cholesterol-fed cellulose controls, all oat fibers altered the response to cholesterol feeding as indicated by 25-45% lower total lipoprotein cholesterol, 40-60% lower VLDL + LDL cholesterol, and 25-40% higher HDL cholesterol contents, P less than 0.01. The effect of the oat fibers on VLDL composition was especially pronounced as demonstrated by 30-65% lower VLDL protein, VLDL apo E and plasma apo B concentrations. The processed oat product which contained 40% more soluble fiber than oat bran or oat flour normalized the lipoprotein profile associated with ingestion of the atherogenic diet significantly more than oat bran or oat flour. Concentration of total lipoprotein cholesterol and distribution of apo E among the VLDL and LDL fractions in the processed oat product group were similar to controls not fed cholesterol. These data indicate that ingestion of oat fiber tends to normalize the lipoprotein profile induced by feeding an atherogenic diet in the rat, and that the hypocholesterolemic effect of oat fiber is associated with its soluble fiber content.

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↗

PubMed1982

Characteristics of microsomal reduction of benzo[a]pyrene 4,5-oxide.

NADPH-reduction of benzo[a]pyrene 4,5-oxide (BP-4,5-oxide) to BP required four components from rat liver: cytochrome P-450, NADPH cytochrome P-450 reductase, phosphatidylcholine and a soluble, heat-sensitive factor which was present in 105 000 X g supernatant and was also released from microsomes by sonication. The requirement for this factor contrasts with recently reported results from Sugiura et al. (Cancer Res., 40 (1980) 2910). Oxide-reduction was 40 times faster under anaerobic conditions, but oxygen did not affect the stimulation factor. This stimulation was highest (X15) at low concentrations of microsomal protein (less than 0.1 mg/ml) and was almost absent at high concentrations of microsomal protein (greater than 1 mg/ml). Oxide-reduction activity was proportional to microsomal protein concentration in the presence of added 105 000 X g supernatant, but for microsomes alone (greater than 0.1 mg/ml) exhibited a parallel plot with an intercept at 0.08 mg/ml microsomal protein. Stimulation was highest at high concentrations of BP-4,5-oxide and a linear plot of V-1 vs. [BP-4,5-oxide]-1 was only obtained in the presence of 105 000 X g supernatant (Km = 3 microM, Vmax = 3.3 nmol/mg/min). Microsomal hydration of BP-4,5-oxide (inhibited in reductase assays) was unaffected by 105 000 X g supernatant, suggesting that stimulation of oxide-reduction did not derive from solubilization of BP-4,5-oxide. Stimulation was observed in the initial rate of reaction and was independent of incubation time. Inhibition of lipid peroxidation, removal of peroxides and deoxygenation were all excluded as explanations of the stimulatory effect.

Anaerobiosis↗

PubMed1977

Effects of branched-chain amino acid antagonism in the rat on tissue amino acid and keto acid concentrations.

Growth rate, plasma amino acid, and alpha-keto acid concentrations and activities of the branched-chain amino acid degradative enzymes of rats were measured. Effects of ingestion of excessive amounts of branched-chain amino acids on these variables were determined. Excessive intake of a single branched-chain amino acid led rapidly to elevated plasma concentration of both the amino acid administered and its corresponding alpha-keto acid and, if the rats had previously been fed a low protein diet, to an increase in liver branched-chain alpha-keto acid dehydrogenase activity. Only leucine caused, in addition, marked growth and food intake depression and decreased plasma isoleucine, valine, alpha-keto-beta-methylvaleric acid and alpha-keto isovaleric acid concentrations. The growth depression was associated food intake depression and could be moderated by addition of isoleucine and valine to the diet. The decreases in plasma isoleucine, valine, alpha-keto-beta-methylvaleric acid and alpha-keto isovaleric acid were not caused by increased degradation of these metabolites to carbon dioxide as branched-chain amino acid oxidation rates in vivo were unchanged by leucine loading and the degradative enzymes were unchanged in adequately fed rats. The decreased concentrations of these amino and keto acids may be the result of decreased protein degradation or increased protein synthesis, possibly mediated by insulin.

Alanine↗

PubMed1976

Branched-chain amino acid oxidation by isolated rat tissue preparations.

Branched-chain amino acid transaminase activity, branced-chain alpha-keto acid dehydrogenase activity, and leucine oxidation were measured in homogenates and slices of several rat tissues. Transaminase activity was highest in heart, while dehydrogenase activity was highest in liver. Leucine oxidation in isolated tissues may be limited by either transaminase or dehydrogenase activity depending upon the relative activities of these two enzymes in the tissue. The results suggest that, as the load of branched-chain amino acids increases, the liver may become an increasingly important site for the degradation of branched-chain alpha-keto acids.

Animals↗