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Biomedical subjects

E B Feldman

Publications and source records attributed to E B Feldman.

At least 55 records · Page 3Linked to original sources
PubMed1986

Nutrition knowledge of senior medical students: a collaborative study of southeastern medical schools.

The Southeastern Regional Medical-Nutrition Education Network (SERMEN) comprises 11 medical schools with varied nutrition training programs. A faculty representative from each school rated 41 topics in nutrition as to their importance for medical practice. From the seven topics unanimously chosen, a 90-item examination was prepared using the University of Alabama School of Medicine's Nutrition Test-Item Bank. Thirteen additional items surveyed student attitudes toward their nutrition training. Twenty-one percent of senior students from 10 SERMEN schools took the examination. Results showed significant variation in knowledge levels among the schools on the overall examination and on the seven topics. Eighty-five percent were dissatisfied with the quantity and 60% with the quality of their medical-nutrition education. Knowledge scores correlated with the students' assessments with r values of 0.28 and 0.35, respectively (p less than 0.001). Findings indicate significant variation in nutrition knowledge of US medical students.

Attitude of Health Personnel↗
PubMed1983

Intestinal lymph lipoproteins in rats fed diets enriched in specific fatty acids.

Four groups of rats were fed test diets with fats providing 75% of fatty acids as palmitate, stearate, oleate or linoleate. Absorption of radiolabeled cholesterol and the specific triglyceride into intestinal lymph lipoproteins and the lipid and protein content and composition of intestinal lymph were compared. Cholesterol and triglyceride absorptions were correlated significantly and were less with the saturated fatty acid diets. The fatty acid patterns of triglyceride-rich lymph lipoproteins mirrored the diet. Exogenous cholesterol was recovered primarily in chylomicrons, except with linoleate. In contrast, radiolabeled saturated fatty acids were recovered primarily in very low density lipoproteins and unsaturated fatty acids were recovered in chylomicrons. Lymph chylomicron size and lipid content were greater with unsaturated fat diets. Triglyceride-rich intestinal lipoproteins of rats fed saturated fats were polygonal by electron microscopy, related to the cooling of lymph samples below body temperature. A-I apolipoproteins were increased in relation to C apoproteins as lipid absorption was greater. Plasma triglycerides in all groups increased compared to rats fed the stock diet. A diet enriched in one specific fatty acid has its unique effects on lymph lipoprotein formation presumably affecting some intestinal subcellular mechanisms. Diet-induced changes in plasma lipids and lipoproteins are not directly related to these as yet unknown mechanisms.

Animals↗
PubMed1983

Dietary saturated fatty acid content affects lymph lipoproteins: studies in the rat.

We examined effects on intestinal absorption of cholesterol and triglycerides and intestinal lipoprotein formation by feeding rats diets in which saturated fatty acids (palmitic plus stearic) comprised 78%, 68%, 48%, or 38% of triglyceride fatty acids. Absorption into lymph of radiolabeled cholesterol was proportional to triglyceride absorption. The rates of absorption of these lipids were related inversely to the % saturated fatty acids fed. The distribution of newly absorbed cholesterol and triglyceride into intestinal lipoproteins differed. With increasing cholesterol absorption more was recovered in very low density lipoproteins in contrast to the appearance preferentially in chylomicrons of larger quantities of fatty acid. Lymph lipid content did not reflect a consistent pattern in relation to the experimental diet fed. The fatty acid composition of triglyceride-rich lymph lipoproteins resembled the diet closely. One-quarter of the intestinal lymph particles from rats fed the highly saturated diets was flattened and polygonal as judged by electron microscopy if cooled to room temperature; whereas with the same diets, particles collected and isolated at 37 degrees C were round. Proportions of A-I and C apolipoproteins in triglyceride-rich intestinal particles varied inversely; apoA-I increased as fat/cholesterol absorption was greater. Diet-induced alterations in plasma lipoproteins and increased circulating triglycerides in this study in rats were unrelated to the variations in intestinal absorption or lymph lipoprotein formation.

Animals↗
PubMed1982

Physical studies of d less than 1.006 g/ml lymph lipoproteins from rats fed palmitate-rich diets.

At body temperature the stable form of triglycerides rich in saturated fatty acids is crystalline. We examined the physical state of triglyceride-rich lymph lipoproteins from rats fed saturated fat, as a function of temperature. When chylomicrons and very low density lipoproteins were collected, isolated, and examined at 37 degrees C, they were liquid as judged by differential scanning calorimetry, x-ray diffraction analysis and proton nuclear magnetic resonance spectroscopy, and they appeared spherical by electron microscopy. At 23-26 degrees C, triglyceride began to crystallize in the alpha form, which transformed to the stable beta form at lower temperatures. On cooling from 23 degrees C to 17 degrees C, considerable crystallization occurred and the particle density was increased significantly. When lipoproteins were held at 0-7 degrees C, about 75% of the triglyceride crystallized, distorting the lipoprotein shape. Reheating from 0 degrees C to 37 degrees C left 25% of the triglyceride unmelted. Heating to 58 degrees C was necessary to melt all the crystallized triglyceride and to restore the spherical lipoprotein shape. After complete melting of cooled lipoproteins, the liquid state was maintained on recooling to 37 degrees C, with formation of a metastable particle similar to the nascent lipoprotein. Isolation of lipoproteins containing highly saturated triglyceride at temperatures below 23-26 degrees C results in partial crystallization, alters their physical properties, and may affect their metabolism.

Animals↗
PubMed1979

Effects of tristearin, triolein and safflower oil diets on cholesterol balance in rats.

Diets containing relatively homogeneous triglycerides composed of 18-carbon chain saturated, monounsaturated or polyunsaturated fatty acids were fed to rats. Cholesterol absorption and turnover were studied. Cholesterol absorption was significantly less in rats fed tristearin than in animals fed triolein or safflower oil. Cholesterol removal from plasma was fastest in rats fed tristearin and slowest with safflower oil and triolein. Plasma cholesterol levels were lowest with tristearin and highest with safflower oil. Increased cholesterol in high density lipoproteins was observed with tristearin and triolein. Lymph and hepatic cholesterol, and lymph triglycerides were highest with safflower oil, suggesting endogenous mobilization. Cholesterol production was least with triolein. Sterol synthesis was greatest with tristearin, perhaps attributable to decreased negative feedback analogous to effects of cholestyramine. Differences in lipoprotein composition observed with the various diets are important since effects on particle size and shape may influence removal mechanisms. The mechanisms underlying the different effects of dietary triglycerides on sterol absorption and metabolism remain to be elucidated.

Animals↗
PubMed1979

Effects of diets of homogeneous saturated triglycerides on cholesterol balance in rats.

The effects of a diet of 10% homogeneous triglycerides of 12 to 18-carbon chain saturated fatty acids on cholesterol absorption and turnover were studied in rats. Cholesterol absorption was successively significantly less in rats fed tristearin than in groups fed tripalmitin, trimyristin and trilaurin. Lesser fatty acid absorption may explain the differences in part, since cholesterol absorption was significantly correlated with fat absorption. Cholesterol removal from plasma was fastest in rats fed tristearin. Plasma cholesterol levels were increased with the trilaurin diet although the rate of cholesterol accumulation in lymph after gavage was slower with trilaurin. Lymph triglycerides were highest with trilaurin and trimyristin diets perhaps indicating endogenous mobilization of triglyceride for lipoprotein formation. Lymph triglycerides were, however, decreased with tristearin. Sterol turnover (production, absorption plus synthesis) was increased with tristearin or trilaurin by kinetic or balance methods.

Animals↗
PubMed1977

Conjugated dihydroxy bile salt inhibition of glucose influx in rat jejunum in vitro.

Effects of bile salts on intestinal transfer differ in diverse animal preparations exposed to various bile acids. Radiolabeled glucose influx into rat jejunum in vitro was studied in buffer and compared to taurodeoxycholate, taurochenodeoxycholate, taurocholate, and deoxycholate. Jejunum was obtained from intact, bile-diverted, and colestipol-treated rats and in similar categories after abdominal x-irradiation. Taurodeoxycholate but not taurocholate inhibited glucose influx only in bile-fistula and colestipol-treated rats. Bile diversion increased and colestipol decreased glucose uptake from buffer. Added inhibitory effects of irradiation and bile salts were seen in bile-fistula animals. These data suggest that normal exposure to bile is chronically inhibiting jejunal glucose transport and that dihydroxy bile salts are responsible for this effect. They do not provide an explanation for the role of bile in the intestinal radiation syndrome.

Abdomen↗
PubMed1976

Bile salts and bioelectric properties of rat jejunum.

Addition of conjugated bile salts increased transmural- and transserosal-potential differences of sheets of rat jejunum. Removal of Cl- from buffer solutions minimized the bile-sale induced bioelectric changes. Bile-salt induced doubling of tissue resistance was not explained by an observed increase in net Cl- serosa leads to mucosa flux. Electrical effects were unrelated to concentration and were observed only when bile-salt solutions perfused the jejunal mucosa. The molecular events associated with bile-salt interactions with the plasma membrane affecting ion fluxes may relate to their unique effects on sterol absorption.

Animals↗
PubMed1975

Surfactants and bioelectric properties of rat jejunum.

The effects of surfactants on bioelectric properties of rat jejunum were determined. Tween 80 (nonionic) and sodium dodecylsulfate (anionic) increased transmural potential differences 20-34% over values in Krebs-Ringer bicarbonate buffer. Short-circuit currents increased 66-112% and net tissue resistance decreased 19-30%. The cationic surfactant cetrimide decreased transmural potential 23%; short-circuit current decreased 32%, and resistance increased 22%. When sulfate replaced chloride in buffer, surfactant effects were minimized or reversed suggesting a role of Cl- flux in the bioelectric effects. Cationic surfactant effects on current and resistance were in the same direction as, but of greater and lesser magnitude, respectively, than alterations observed with bile salts. The current increase was of greater magnitude and resistance decrease less marked. Surfactant molecules may interact specifically with membranes in a more complex manner than simple "detergency".

Animals↗