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C Andrieux

Publications and source records attributed to C Andrieux.

At least 37 records · Page 2Linked to original sources
PubMed1995

Degradation and fermentation of alpha-gluco-oligosaccharides by bacterial strains from human colon: in vitro and in vivo studies in gnotobiotic rats.

The ability of several human gut bacteria to break down alpha-1,2 and alpha-1,6 glycosidic linkages in alpha-gluco-oligosaccharides (GOS) was investigated in vitro in substrate utilization tests. Bacteroides thetaiotaomicron, Bifidobacterium breve and Clostridium butyricum, which are usually found in the infant gut and have been associated with both beneficial and deleterious effects on health, were studied. Alpha-Gluco-oligosaccharide degradation was compared in vitro and in vivo in gnotobiotic rats associated with these organisms, inoculated alone or in combination. Oligomer breakdown and short chain fatty acid and gas production indicated hydrolysis and fermentation of the substrate. In vitro and in vivo, Cl. butyricum was the least efficient in utilizing GOS, whereas Bact. thetaiotaomicron was the most efficient. Kinetic studies on GOS hydrolysis in pH-regulated fermenters showed that alpha-1,2 glucosidic bonds, which characterize the substrate, were more resistant than alpha-1,6 linkages. Adaptation of gnotobiotic rats to a diet containing 2% (w/w) GOS significantly increased the hydrolysis of alpha-1,2 glucosidic bonds. Combination of bacteria in trixenic rats improved GOS degradation and inhibited Cl. butyricum metabolism. This inhibition was confirmed in pH-regulated fermenters containing GOS as the principal carbon source. The association of beneficial bacteria and GOS may therefore have a potential health-promoting effect in human neonates.

Animals↗
PubMed1994

Evidence for the absence of participation of the microbial flora in the hypocholesterolemic effect of guar gum in gnotobiotic rats.

Germ-free (GF) and heteroxenic (Hx) rats were given a hypocholesterolemic diet (Hyper) with or without 5% guar gum (GG) for 4 weeks. The GF and Hx rats fed GG diets showed a lower hepatic and plasmatic cholesterol level when compared with Hyper groups. This reduction of cholesterolemia was due to a decrease in the chylomicron + very low density lipoprotein (VLDL) fraction. The caecal and portal concentrations of propionate were 30% higher in Hx rats fed the GG diet than in Hx rats fed the Hyper diet. These results exclude the participation of the intestinal microflora in the hypocholesterolemic effect of GG, and show that guar gum nullifies the effect of the hypocholesterolemic diet in the GF rats.

Animals↗
PubMed1994

Heat or gamma irradiation sterilization affects the hypocholesterolemic effect of guar gum in axenic and heteroxenic rats.

1. Twenty-two axenic (germfree) or thirty heteroxenic (axenic colonized with human flora) 2.5-3.5 months old female Fisher rats were fed for four weeks either a hypercholesterolemic (HYPER) diet or a HYPER diet containing 5% guar gum (GG) sterilized by heat or by gamma irradiation. 2. Axenic rats fed the irradiated GG diet had higher cholesterolemia than their counterparts fed an autoclaved diet (4.50 vs 2.29 mmol/l), whereas the method of sterilization had no effect on plasma cholesterol in axenic HYPER or heteroxenic animals (7.35 vs 6.51 mg/dl). 3. The levels of hepatic esterified cholesterol were higher in heteroxenic animals fed the irradiated GG diet than in their counterparts fed the autoclaved GG diet (5.65 vs 3.57 mmol/g tissue). 4. The composition of volatile fatty acids in the cecal content of heteroxenic rats was dependent on the method of sterilization regardless of the presence of fiber: the levels of butyrate were 2.88 and 0.85 mumol/g for rats fed the autoclaved and irradiated diets, respectively. 5. Gamma irradiation abolished the cholesterol-lowering effect of guar gum, whereas sterilization by heat preserved this effect. 6. The hypocholesterolemic effect of guar was reduced by gamma irradiation sterilization and was probably mediated by qualitative changes in the intestinal microflora which interfered with bile acid absorption.

Animals↗
PubMed1993

Effects of galacto-oligosaccharide and bacterial status on mucin distribution in mucosa and on large intestine fermentation in rats.

The purpose of the present paper was to study the effects of a dietary undigestible carbohydrate and intestinal microflora on mucin distribution (neutral, acid, sulphonated), glycolytic activities: beta-D-galactosidase (EC 3.2.1.23), N-acetyl-beta-D-galactosaminidase (EC 3.2.1.43), N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30), alpha-L-fucosidase (EC 3.2.1.51) and bacterial metabolism (gas production, short-chain fatty acids (SCFA) and lactic acid caecal concentration) in germ-free (GF), conventional (CV) and heteroxenic (HE) rats (GF rats associated with a human flora). Rats were fed on either a control diet or a diet containing 40 g trans-galactosylated oligosaccharide (TOS)/kg. In GF rats fed on the control diet caecal pH was almost neutral and glycolytic activities negligible. The number of mucus-containing cells increased from the caecum to the colon for the three types of mucin. TOS had no effect in the caecum but it modified mucin cell repartition in the colon. In CV and HE rats fed on the control diet caecal pH was similar (6.8), but caecal SCFA and lactic acid concentrations (mumol/g) and gas production (ml/24 h) were higher in CV (70, 5.9 and 2.3 respectively) than in HE rats (32, 4.6 and 0.4 respectively). In CV, as in HE rats, acid-mucin-containing cells increased from the caecum to the colon and glycolytic activities were similar. TOS reduced acid-mucin-containing cells in the caecum of CV rats by twofold but had no effect in either the caecum or the colon of HE rats. TOS strongly increased beta-galactosidase activity and slightly modified the other glycolytic activities. Its effect on bacterial metabolites depended on bacterial status. However, comparison between CV and HE rats showed no evident relationship between the number of mucus-containing cells and measured bacterial metabolites. Differences between CV and HE rats might be due to bacterial microflora specificity. TOS had an intrinsic effect on mucus cell distribution in the colon of GF rats. In CV and HE rats the presence of the flora abolished this effect.

Animals↗
PubMed1992

Intestinal mucosal morphometry and ileal epithelial renewal in conventional and germ-free rats fed an amylomaize starch diet.

Intestinal mucosal morphometry and ileal epithelial renewal were studied in conventional (CV) and germ-free (GF) rats fed either poorly digestible amylomaize or normal maize starch diets. Intestinal morphometry and position of labelled enterocytes were studied at various times after tritiated thymidine injection. With amylomaize starch diet, no difference was observed in the size of crypts (C), villi (V) and C + V between duodenum and jejunum both in CV and GF rats. In the ileum, however, values were significantly lower than those in the duodenum and jejunum. Furthermore, the presence of the microbial flora led to higher values when compared with GF values. Despite the morphological modifications in the ileum, no significant difference was detected in the labelled cell positions and epithelial renewal time between CV and GF values. This suggests that the resistant part of amylomaize starch was responsible for the modification in mucosal morphometry and the longer ileal epithelium renewal time in CV rats which then becomes similar to that in GF rats.

Amylopectin↗
PubMed1992

Contribution of the digestive tract microflora to amylomaize starch degradation in the rat.

To study in vivo the contribution of the bacterial flora to amylomaize starch degradation in the rat, germ-free and conventional rats were fed on a diet containing either a normal maize starch or an amylomaize starch. In germ-free rats maize starch was almost totally digested in the small intestine, whereas 40% of the ingested amylomaize starch reached the caecum and 30% was excreted, despite the very high endogenous amylase activity. Study by transmission electron microscopy of germ-free caecal contents showed an endocorrosion of the starch granule. In conventional rats, as in germ-free rats, digestibility of maize starch reached 98% in the small intestine, whereas that of amylomaize starch was only 60%. In the caecum of these rats amylomaize starch was fermented, and this led to a decrease in caecal pH and to formation of short-chain fatty acids (SCFA), especially propionate. Comparison between conventional rats fed on maize starch or amylomaize starch showed that caecal SCFA concentrations during a circadian cycle varied in the same way whereas total SCFA and lactic acid concentrations were much higher in rats fed on amylomaize starch. Amylase (EC 3.2.1.1) activity was similar in the caecal contents of conventional rats whatever the ingested starch. It was lower in conventional than in germ-free rats, but no starch granule remained in the caecum of conventional rats. These results showed that bacterial amylase was more efficient at degrading resistant amylomaize starch than endogenous amylase.

Amylases↗
PubMed1991

Identification and properties of an alpha-amylase from a strain of Eubacterium sp. isolated from the rat intestinal tract.

1. A bacterial amylase was isolated from the intestinal content of monoxenic rats inoculated with Eubacterium sp. B86. 2. Affinity chromatography on cross-linked starch allowed its separation from rat endogenous amylases. 3. The bacterial enzyme was characterized by its pI, molecular weight and action pattern. It behaves as a typical endo-amylase (alpha-amylase).

Animals↗
PubMed1989

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. Irrespective of the poorly digestible carbohydrate, the variation of bacterial transformation always occurred in the same way: the bacterial transformation of beta-muricholic acid into hyodeoxycholic acid was the first to disappear, while omega-muricholic acid formation increased; second, cholic acid transformation decreased and finally all bile acid transformations were strongly affected. There was a significant correlation between bile acid transfer and the minimal caecal pH in vivo. This effect of pH was similar in vitro. To determine whether the levels of bacteria which transformed bile acids were modified, rats fed on the highest amounts of poorly digestible carbohydrates were introduced into isolators and carbohydrate feeding was stopped. Caecal pH recovered its initial value but bile acid transformations remained changed, suggesting that the intestinal microflora were modified by ingestion of fermentable carbohydrates.

Animals↗
PubMed1986

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. Feed intake was similar in all groups of rats except GF rats fed amylomaize starch ad libitum, whose feed intake was higher. One group of GF rats received amylomaize starch in restricted amounts (pair-fed rats). A balance study of energy, nitrogen and minerals (Ca, P, Mg, Na, K, Fe, Mn, Zn and Cu) was performed. Apparent absorption of Mg, P, Na, K and Zn (expressed as a percentage of the amount ingested) was lower in GF rats fed amylomaize starch than in GF rats fed maize starch. Since feed intake was higher in GF rats fed amylomaize starch ad libitum than in rats fed maize starch, mineral absorption (expressed in milligrams per day) was not reduced in rats fed ad libitum, whereas it was reduced in pair-fed rats. Mineral retention was similar in GF rats fed ad libitum, but was reduced in pair-fed rats. In CV rats fed amylomaize starch, cecal weight and cecal volatile fatty acids concentration were higher than those in CV rats fed maize starch. Apparent absorption of N and P was lower and that of Ca, Mg and Fe was higher in CV rats fed amylomaize starch than in rats fed maize starch.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1985

Inhibitory effect of a copper-dipeptide complex on the establishment of a Clostridium perenne strain in the intestinal tract of gnotobiotic mice.

A semisynthetic diet fed to axenic mice was found to prevent the establishment of a Clostridium perenne strain in their intestinal tract. This inhibitory effect did not occur when axenic mice were preinoculated with a strain of Clostridium difficile. The inhibitory effect was related to the presence in the intestinal contents of axenic mice of both dietary copper and a dipeptide, aspartic-epsilon-lysine. When C. difficile was inoculated into axenic mice, the dipeptide disappeared from the digesta, and C. perenne became established even in the presence of high concentrations of copper.

Animals↗
PubMed1984

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. MRP caused a change in apparent absorption of calcium and magnesium in germfree (GF) and conventional (CV) rats. The absorption of these minerals was reduced in the small intestine of CV and GF, perhaps due to the action of MRP on enterocyte metabolism. This effect was compensated for only in CV rats by increased absorption of these minerals in the cecum and the colon. The presence of microflora and the increase in cecal volume in CV rats suggested that MRP fermentation increased mineral absorption in the cecum and colon. However, although total apparent absorption of magnesium and phosphorus was higher in CV rats ingesting MRP, the urinary excretion of these minerals was also higher and their retention was not better. The effect of MRP in GF rats was not compensated for in the cecum, and mineral retention was significantly reduced in GF rats ingesting MRP.

Animals↗
PubMed1983

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. The patterns of TiO2 and 45Ca excretion were similar, indicating that TiO2 was a good marker of unabsorbed calcium transit. The apparent absorption coefficient of calcium, magnesium and phosphorus was determined in the ileum, caecum, large intestine and faeces by the mineral/TiO2 ratio. The effects of microflora and lactose varied with the mineral and the digestive tract level studied. --In the small intestine, microflora had no effect on the apparent absorption of calcium and magnesium but did have an unfavorable influence on phosphorus absorption. Lactose increased calcium and magnesium absorption, and this increase was similar in GF and CV rats, but lactose had a favorable effect on phosphorus absorption only in CV rats. --In the caecum, microflora had an unfavorable effect on the apparent absorption of calcium and magnesium and a favorable effect on phosphorus absorption. The ingestion of lactose reduced calcium and magnesium absorption in the caecum of GF rats and phosphorus absorption in the caecum of CV animals. --In the colon, mineral absorption was not significant in either CV or GF rats receiving the lactose-free diets. Lactose ingestion caused the absorption of calcium, magnesium and phosphorus to rise significantly only in GF rats. This absorption contributed to the stronger effect of lactose on total calcium and phosphorus absorption in GF rats.

Animals↗
PubMed1982

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. On the contrary, it increased the absorption and retention of calcium, phosphorus and magnesium. The favourable effect of lactose on magnesium metabolism was not different in GF and CV rats. On the contrary, lactose increased the absorption and retention of phosphorus and calcium more in GF than in CV animals. It augmented the amount of calcium present in a soluble, ultrafiltrable form in the caecum of only the GF rats. These results are discussed and compared to previous data on younger rats. They lead to the hypothesis that the voluminous caecum of the GF rat is the site of a calcium absorption which is accentuated by presence of lactose in the diet.

Animals↗
PubMed1980

Effects of lactose and mode of sterilization of a lactose diet on mineral metabolism in germ-free and conventional rats.

Mineral balances of Ca, P, Mg, K, Na, Zn, Mn, Cu were carried out on 6-week old Fisher rats for 14 consecutive days. Four lots of germfree (GF) and 4 lots of conventional (CV) rats were fed a semi-synthetic diet at weaning containing either 0 or 10 p. 100 of lactose (L). The diet was sterilized either by irradiation (I) or by autoclave (Au). Lactose, when added to the diet, caused very variable modifications of the mineral metabolism, depending on the mineral studied and the mode of sterilization. Thus, retention and apparent absorption of iron were hardly changed by the presence of lactose. On the other hand, those of Mn were strongly enhanced by the lactose. The action of the other minerals was complex; it was modulated either by the mode of diet sterilization, the flora, or by both factors simultaneously. The IL diet increased retention of most of the minerals; in some cases (Na, Zn, P, Ca) it was only evidenced in CV rats; in other cases (Mn, Mg, Cu) its action was visible in both CV and GF animals. Steam-sterilized lactose (AuL) considerably reduced this effect and even reversed it. This change in lactose action under the effect of steam sterilization especially affected absorption, which declined for all the minerals, except Zn and Mn. It was accompanied by a drop in the digestive efficiency ratio which was particularly pronounced in GF rats. The destruction of 1/3 of dietary lactose by steam sterilization could not alone explain the differences between the effects of IL and AuL. Other factors, such as the products of the Maillard reaction formed by steam sterilization of the diet, might be implicated.

Animals↗
PubMed1980

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. The addition of these products caused diarrhoea in axenic animals, thus preventing a good estimation of apparent absorption. It led to a significant decrease in the retention of calcium, phosphorus, magnesium and copper only in the axenic rats. It is shown that MRP affect mineral metabolism and that the microflora plays a protective role in the physiology of digestion.

Animals↗
PubMed1978

[Effects of mode of food sterilization on mineral absorption in germ-free and conventional rats].

Minéral balances of P, Ca, Mg, Na, K, Mn, Fe and Cu were determined for three groups of holoxenic rats (CV) fed a non sterilized (CVN), steamsterilized (CVA) or irradiated (CVI) diet and for two groups of axenic (GF) rats fed a steam-sterilized (GFA) or irradiated (GFI) diet. In the group of CV rats as compared to CVN group of rats, the CVA and CVI rats retained less Cu and more Fe and Mn, their urinary excretion of P and Mg was higher and they retained less Mg. Comparison between CV and GF rats showed that the apparent absorption and retention of Ca, P, Mg, Mn, Cu were higher in GF than in CV rats. On the contrary, the apparent absorption of Na and K was lower in GF than in CV rats. However, the observed differences were modified by the mode of diet sterilization. Thus, with respect to the apparent absorption of Na, K, Mn and urinary excretion of Mg, the differences between CV and GF rats were larger when the diet was irradiated than when it was steam-sterilized. On the contrary, the apparent digestibility and urinary excretion of Mg, the apparent absorption and retention of Fe were more modified when the diet was steam-sterilized than when irradiated. For some parameters of the metabolism of Na, K, Fe, Mn, Mg, and P measured in GF rats, the differences observed between GFA and GFI rats were larger than in CV rats. Accordingly, the mode of sterilization is liable to modify the metabolism of some minerals and the microbial flora of the digestive tract is capable of modifying this action.

Animal Feed↗