Effects of some poorly digestible carbohydrates on bile acid bacterial transformations in the rat.

The effects of ingestion of poorly digestible carbohydrates on bacterial transformations of cholic acid and beta-muricholic acid were studied in rats fed on increasing levels of lactose, lactulose, amylomaize or potato starches. Each level was given for 3 weeks and, at the end of each dietary treatment, bile acid faecal composition was analysed and a group of six rats was killed every 4 h during 24 h to determine the amounts of fermented carbohydrate and fermentation characteristics (caecal pH, volatile fatty acids (VFA) and lactic acid concentrations). Fermentation of carbohydrates decreased caecal pH and enhanced caecal VFA and lactic acid concentrations.

Effective glucuronidation of 6 alpha-hydroxylated bile acids by human hepatic and renal microsomes.

The glucuronidation of bile acids is an established metabolic pathway in different human organs. The hepatic and renal UDP-glucuronyltransferase activities vary according to the bile acids concerned. Thus, hyodeoxycholic acid is clearly differentiated from other bile acids by its high rate of glucuronidation and elevated urinary excretion in man.

beta-Muricholic acid; potentiometric and cholesterol-dissolving properties.

Some physicochemical properties of beta-muricholic acid (3 alpha,6 beta,7 beta-trihydroxy-5 beta-cholanic acid), a major bile acid biosynthesized by rat liver, were determined and compared to those of ursodeoxycholic and chenodeoxycholic acids. From potentiometric studies, the following characteristics of beta-muricholic acid were shown: a low monomer solubility (13 microM), a high equilibrium precipitation pH (7.92 for 30 mM solution), an apparent critical micellar concentration of 4 mM, and a very low micellar capacity of the bile salt to dissolve the protonated bile acid.

Effects of amylomaize starch on mineral metabolism in the adult rat: role of the microflora.

The effects of amylomaize starch on rat mineral metabolism were studied. To elucidate the role of bacterial fermentation, the effects of amylomaize starch were compared in germfree (GF) and conventional (CV) rats. A purified diet, sterilized by irradiation and containing either maize starch (M) or amylomaize starch (A), was fed to the rats.

Glucuronidation of bile acids in human liver, intestine and kidney. An in vitro study on hyodeoxycholic acid.

The activities of UDP-glucuronyl transferase(s) in homogenates and microsomal preparations of human liver, kidney and intestine were tested with hyodeoxycholic acid (HDC). The various kinetic parameters of the UDC-glucuronidation were determined from time course experiments. In both liver and kidney preparations, HDC underwent a very active metabolic transformation: liver Km = 78 microM, Vmax = 3.

Metabolism of beta-muricholic acid in man.

Labeled beta-muricholic acid was obtained from germfree rats given [24-14C]-chenodeoxycholic acid. It was crystallized with the same unlabeled bile acid extracted from germfree rat pooled biles. Five patients fitted with a T-tube after cholecystectomy were given orally 100 mg of the bile acid.

Increase in the ileal absorption rate of sodium taurocholate in germ-free or conventional rats given an amylomaize-starch diet.

Twenty germ-free and twenty conventional male Fischer 344 rats, 3 months old, were fed ad lib. diets based either on normal or on amylomaize starch for 1 month. The absorption rate of sodium taurocholate, 25 mmol/l, was determined in vivo in jejunal or ileal segments.

beta-Glucuronidase activities of intestinal bacteria determined both in vitro and in vivo in gnotobiotic rats.

The beta-glucuronidase activities of bacterial strains isolated from the rat intestinal tract were studied both in vitro in culture media and in vivo in the intestinal contents of gnotobiotic rats. Only 50 of 407 strains tested were found to be positive in vitro. They belonged to the three genera Clostridium, Peptostreptococcus, and Staphylococcus.

Dietary fiber and cholesterol and bile acid metabolism in axenic (germfree) and holoxenic (conventional) rats. III. Effect of non-sterilized pectin.

Axenic (germfree) and holoxenic (conventional) rats were given a pectin-containing diet (5%) or a pectin-free diet. The diet was not sterilized and the axenic state was maintained by the addition of antibiotics. Pectin modified little or not at all the quantity of bile acids in the small intestine, fecal bile acid excretion and fecal elimination of the sum of cholesterol and bile acids.

Absence of transformation of beta-muricholic acid by human microflora implanted in the digestive tracts of germfree male rats.

Germfree rats biosynthetize cholic and beta-muricholic acids. The latter does not exist in humans. Germfree rats were given human fecal suspensions.

Effects of microflora on the dimensions of enterocyte microvilli in the rat.

The length and diameter of enterocyte microvilli at mid-villus position were measured on electron-micrographs. The duodenum, jejunum and ileum of axenic (germfree) and holoxenic (conventional) inbred rats fed the same diet have been studied. The microvilli were significantly shorter in all these intestinal regions when the microflora was present.

Effects of Maillard's reaction products on apparent mineral absorption in different parts of the digestive tract. The role of microflora.

1.5 and 3% of Maillard's reaction products (MRP), prepared by heating glycine and glucose, were incorporated ino a semi-synthetic diet. The diet was sterilized by irradiation.

Effect of wheat bran upon gastro-intestinal transit in germ-free and conventional rats.

Germ-free and conventional rats were fed a semi-synthetic diet including 10% wheat bran for 1 month. They were compared to similar rats fed the same diet without bran. Transit of polyethylene glycol (PEG) 4000 was studied in giving the marker either in saline or in the diet.

Intestinal absorption, excretion, and biotransformation of hyodeoxycholic acid in man.

Five patients fitted with a biliary T-tube after cholecystectomy were given orally a tracer dose of [14C]hyodeoxycholic acid and 500 mg of the same unlabeled acid. Intestinal absorption and biotransformation, liver metabolism, bile secretion, fecal and urinary excretions of this acid or of its metabolites were studied. Hyodeoxycholic acid was well absorbed by the human intestine.

[Characterization of the antigen in circulating immune complexes and application to the detection of streptococcal antigens in human infectious endocarditis].

Immune complexes from patients with subacute endocarditis were used to develop a methodology for characterization of the antigen involved in human circulating immune complexes. This model was chosen because it permits isolation of the causative agent of the streptococcal infection thought to contain the antigen present in the immune complex. A comparison was made between two methods for characterization of bacterial antigen bound to antibody.

Effect of microflora and lactose on the absorption of calcium, phosphorus and magnesium in the hindgut of the rat.

For 4 weeks, 3-month old germfree (GF) and conventional (CV) rats were given a semi-synthetic diet sterilized by irradiation with or without 10% of lactose. During the 5th week, 0.2% of titanium oxide (TiO2) was added to the diet and the rats were killed at regular intervals throughout the light/dark cycle.

[Biotin deficiency in the germ-free rat and propionic acidemia].

Biotin deficiency was induced in germ-free rats using three experimental protocols. The results showed the important role of biotin during gestation and suckling. The earlier the deprivation, the earlier the deficiency and the severer the symptoms.

Effect of amylomaize starch on cholesterol and bile acid metabolisms in germfree (axenic) and conventional (holoxenic) rats.

Germfree and conventional rats were given a semi-synthetic diet containing either normal cornstarch or an amylomaize starch. The experimental groups thus formed were compared to assess the effects of these two types of starch and to determine if digestive tract microflora was involved in these effects. The presence of amylomaize starch decreased body growth in germfree and conventional rats, increasing food intake in the former and decreasing it in the latter.

Microbial flora in the digestive tract and action of lactose on mineral metabolism.

Germ-free (GF) and conventional (CV) adult rats were given for 4 weeks a semi-synthetic diet containing 10 p. 100 lactose (L) or no lactose (LO). The axenic state had an unfavourable effect on sodium and potassium absorption.

Fat absorption in germ-free and conventional rats artificially deprived of bile secretion.

Bile duct ligation was performed in germ-free and conventional rats in order to study the effects of bile deprivation on the absorption of dietary lipids and the excretion of faecal lipids in the presence or the absence of gastrointestinal flora. The main consequence of bile duct ligation in conventional rats was decrease of about 50% in the apparent absorption of dietary lipids (peanut oil). In germ-free rats, absorption decreased by only about 25%.

Dietary fiber and cholesterol and bile acid metabolisms in axenic (germfree) and holoxenic (conventional) rats. II. Effect of pectin.

Axenic and holoxenic rats were fed with a semi-synthetic diet containing 5 p. 100 pectin as the only fiber. Although the microbial flora of the digestive tract converted most of the bile acids in holoxenic rats, it hardly changed the other characteristics of cholesterol and bile acid metabolisms, except intestinal bile salt pools which were much larger in the axenic rats.

Dietary fiber and cholesterol and bile acid metabolisms in axenic (germfree) and holoxenic (conventional) rats. I. -- Effect of wheat bran.

Axenic (GF) and holoxenic (CV) rats were given a semi-synthetic diet containing no fiber (0) or 10 p. 100 bran (B). The GFO, GFB, CVO and CVB groups were compared to assess the action of the flora and the bran.

Effect of various modifications in the diet on ileal epithelium renewal in germ-free and conventional rats.

Renewal of the ileal epithelium has been studied in germ-free (GF) and conventional (CV) rats fed with a semi-synthetic diet in the following forms: a) pellets sterilized by autoclaving (Pel. Au. diet); b) powder sterilized by gamma irradiation; when given to the rats, its weight in water was added to make a paste (Pa.

Variations of bile salt pool size and secretion rate in rats according to the modes of sterilization and preparation of a semi-synthetic diet.

A semi-synthetic diet was sterilized by irradiation and given to rats as pellets, powder or paste obtained by admixing an equal amount of water. The bile salt pool increased from the first to the third treatment. That effect disappeared when the starch was replaced by sucrose or when the diet was autoclaved instead of irradiated.

Interactions between Maillard's reaction products, the microflora of the digestive tract and mineral metabolism.

3 p. 100 of Maillard's reaction products (MRP), obtained by mild heating of glucose and glycine, were added to a semi-synthetic diet sterilized by irradiation. This resulted in increased dry matter excretion, more marked in axenic than in holoxenic rats, and in reduced apparent absorption of sodium and potassium in holoxenic rats.