Bile acid metabolism and fiber.

Studies in experimental animals and in humans have shown a definite interaction of dietary fiber with bile acid metabolism. In experimental animals, some types of fiber have been shown to increase bile acid excretion as well as increase pool size and turnover of bile acids. In man, increases in bile acid excretion have been observed but not consistently.

Fiber, lipids, and atherosclerosis.

The influence of dietary fiber on lipid metabolism and atherosclerosis in animals and on lipid metabolism in man is reviewed. Pectin, guar gum, and lignin lower serum and liver cholesterol in cholesterol-fed rats. Agar increases liver cholesterol in rats.

Spectrodensitometry of nanogram quantities of cholesterol.

In studies of hydrolysis and synthesis of cholesterol esters by aortic enzymes, conventional methods (aside from isotope methodology) are too insensitive to measure reaction products when few aortas are used. High-performance thin-layer chromatography coupled with spectrodensitometry of plates charred after spraying with a cupric acetate-phosphoric acid reagent permitted quantitation of 10-ng amounts of cholesterol, cholesterol oleate oleate, and oleic acid. Linear calibration curves were obtained after spectrodensitometry of chromatograms containing 10-200 ng of lipid.

Fiber, hypercholesteremia, and atherosclerosis.

Epidemiological data suggest that populations subsisting on high fiber diets are free of a number of the diseases of Western civilization, among them coronary heart disease. Studies in animals and man show that each type of fiber exerts its own specific influence. Thus, in man bran has no effect on serum lipids, but pectin lowers cholesterol levels.

An enzymatic assay for determining free and total cholesterol in tissue.

We describe a method for determining free and total cholesterol in extracts of rat-liver lipids by use of a cholesterol esterase/cholesterol oxidase enzymatic kit (Boehringer Mannheim Corp). The lipids are solubilized (as micelles) directly into the aqueous reagent mixture. Results of the enzymatic method correlate well with those obtained by an acid/ferric chloride assay of digitonin precipitates of the extracts.

Human serum hexosaminidase: elevated B form isozyme in cancer patients.

The activity of N-acetyl hexosaminidase (beta-2-acetamido-2-deoxy-D-glucoside:N-acetamido-deoxyglucohydrolase, E.C. 3.

Cholesterol vehicle in experimental atherosclerosis. Part 15. Randomized butter and randomized lard.

Randomized lard and butter oil were conpared with native lard and butter oil for their effects on cholesterol-induced atherosclerosis in rabbits. In each experiment there was also a group fed corn oil. The diets contained 2% cholesterol and 6% fat and were fed for eight weeks.

Modification by fiber of toxic dietary effects.

There is evidence that type of diet may affect the course of chemical carcinogenesis. In experiments with acetylaminofluorene, rats maintained on stock diet exhibit fewer tumors than do rats fed semi-purified diets. Rats fed stock diet augmented with high levels of sodium cyclamate (2.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 7. Interaction of animal or vegetable protein with fiber.

Rabbits were maintained for 10 months on a semipurified, cholesterol-free atherogenic regimen. All diets contained sucrose (40%) and hydrogenated coconut oil (14%). The protein (25%) was either casein or soya protein and the fiber (15%) was either wheat straw, alfalfa, or cellulose.

Dietary essential fatty acids in cystic fibrosis.

Analyses of serum lipids of children with cystic fibrosis (CF) have indicated a deficiency in essential fatty acids (EFA). In view of a report that intravenous administration of soybean oil emulsions normalized sweat sodium values in CF children, we studied the effects of orally administered essential fatty acids (as corn oil) for one year. Some improvement was noted in all patients, but no one consistent factor predominated.

Diet and cholesteremia.

The statistical correlation between elevated serum cholesterol levels and increased risk of coronary heart disease has channeled thinking towards regarding dietary fat and cholesterol as the principal causes of hypercholesteremia. Since 1909 there have been a number of changes in nutrient availability in the United States. Protein availability is unchanged but the ratio of animal to vegetable protein rose from 1.

Linoleic acid amides: effect on cholesteremia and atherosclerosis.

Several of a series of linoleic acid amides have been reported to inhibit cholesterol-induced atherosclerosis in rabbits. The three amides which have been studied to the greatest extent are (in order of increasing activity) N-cyclohexyl linoleamide (AC23), N(alpha methylbenzyl) linoleamide (AC223), and N[aplha-phenyl-beta-(p-tolyl)ethyl] linoeamide (AC 485). We have found AC223 to inhibit cholesterol absorption in rats and to slightly inhibit exogenous but not endogenous cholesteremia in rabbits.

Hupolipidemic activity of (--)-hydroxycitrate.

The influence of (--)-hydroxycitrate, a potent competitive inhibitor of adenosine triphosphate (ATP) citrate lyase, on serum triglyceride and cholesterol levels, and in vitro and in vivo rates of hepatic fatty acid and chloesterol synthesis was investigated in normal and hyperlipidemic rat model systems. (--)-Hydroxycitrate reduced equivalently the biosynthesis of triglycerides, phospholipids, cholesterol, diglycerides, cholesteryl esters, and free fatty acids in isolated liver cells. In vivo hepatic rates of fatty acid and cholesterol synthesis determined in meal-fed normolipidemic rats were suppressed significantly by the oral administration of (--)-hydroxycitrate for 6 hr, when control animals exhibited maximal rates of lipid synthesis; serum triglyceride and cholesterol levels were significantly reduced by (--)-hydroxycitrate.

Binding of sodium taurocholate by cereal products.

The in vitro binding of sodium taurocholate to various cereal products was determined. Maize meal bound significantly more bile salt than maize rice or samp and significantly less than minitmeal or minitsamp.

Comparison of the binding of various bile acids and bile salts in vitro by several types of fiber.

The binding in vitro of the sodium salts of cholic acid, chenodeoxycholic acid, deoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, taurodeoxycholic acid, glycocholic acid, glycochenodeoxycholic acid, and glycodeoxycholic acid by alfalfa, bran, cellulose, lignin, and cholestyramine was measured. Cholestyramine bound an average of 81.3% of all the bile acids and salts tested whereas cellulose bound only negligible amounts (1.