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Biomedical subjects

O Szylit

Publications and source records attributed to O Szylit.

At least 37 records · Page 2Linked to original sources
PubMed1993

Rape-seed meal toxicity in gnotobiotic rats: influence of a whole human faecal flora or single human strains of Escherichia coli and Bacteroides vulgatus.

Gnotobiotic growing rats harbouring either a whole human faecal flora or single human strains of Escherichia coli (EM0) or Bacteroides vulgatus (BV8H1) were fed for 7 weeks on semi-synthetic diets in which the protein source was either soya-bean meal (SM) or rape-seed meal (RM). For each bacterial status the RM-diet group was compared with the control group fed on the SM diet. The association of human faecal flora with the RM diet was responsible for reduced feed intake and reduced weight gain, an enlargement of the liver and thyroid and a decrease in both thyroxine and triiodothyronine plasma levels. The association of the B. vulgatus BV8H1 strain with the RM diet reproduced all these effects, except that triiodothyronine plasma levels were not significantly modified. Rats inoculated with the E. coli EM0 strain and fed on the RM diet exhibited a goitre and lowered thyroxine and triiodothyronine plasma levels. These results show that the human intestinal microflora may be involved in glucosinolate metabolism when cruciferous vegetables are consumed by man. The specificity of the symptoms observed according to the rat bacterial status supports the hypothesis that bacteria yield specific toxic glucosinolate derivatives according to their enzymic potential.

Animals↗
PubMed1993

Alterations of the hepatic xenobiotic-metabolizing enzymes by a glucosinolate-rich diet in germ-free rats: influence of a pre-induction with phenobarbital.

Germ-free growing rats were fed on a glucosinolate-rich diet (rapeseed-meal-based) and compared with counterparts fed on a glucosinolate-free diet (soya-bean-meal-based), both diets being isonitrogenous and isoenergetic. For each diet half the animals received phenobarbital in drinking water as an inducer of xenobiotic-metabolizing enzymes. Some of the usual deleterious glucosinolate-linked effects, i.e. kidney hypertrophy and reduction in growth and feed intake, were followed and three of the major hepatic xenobiotic-metabolizing enzymes were investigated. Growth rate, dietary intake and kidney weight were not altered by glucosinolates in the absence of intestinal microflora, whether the animals were treated with phenobarbital or not. As far as the hepatic xenobiotic-metabolizing enzymes are concerned, the specific level of cytochrome P450 and the specific activities of glutathione-S-transferase (EC 2.5.1.18) and UDPglucuronosyltransferase (EC 2.4.1.17) remained unchanged in rats receiving the glucosinolate-rich diet compared with the control animals. Despite the low dose given, phenobarbital displayed its usual inducing effect on all three enzymes, similar whatever the diet. A previous counterpart experiment performed with conventional animals had shown that glucosinolate feeding led to large alterations of the variables herein studied, some of these modifications being hugely enhanced by a phenobarbital treatment. Therefore, the present results obtained on germ-free animals prove that alterations of the xenobiotic-metabolizing enzymes induced by glucosinolates are somehow mediated by the intestinal microflora. Furthermore, the involvement of those enzymes in glucosinolate toxicity definitely requires the presence of the intestinal microflora.

Animals↗
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↗
PubMed1990

Glucosinolates toxicity in growing rats: interactions with the hepatic detoxification system.

1. Glucosinolate-rich diet (RM) in growing rats increased liver (a), kidneys (b), and thyroid (c) weights and depleted feed intake (d), growth curve (e) and T4 and T3 plasma levels (f). 2. Oral administration of phenobarbital enhanced the toxic effect of RM on (b), (d) and (e) and did not modify the toxic effect of RM on (a), (c) and (f). 3. RM had a depleting effect on hepatic microsomal P-450 specific activity. 4. RM had an enhancing effect on hepatic glutathione S-transferase and UDP-glucuronyltransferase specific activities. 5. These results indicate that some glucosinolate derivatives released by gut microflora metabolism are further metabolized by the hepatic detoxification system, and that they could play the role of co-toxic or co-detoxic molecules.

Animals↗
PubMed1989

Experimental cecitis in gnotobiotic quails monoassociated with Clostridium butyricum strains isolated from patients with neonatal necrotizing enterocolitis and from healthy newborns.

Using axenic quails fed a diet containing lactose, we have investigated the potentially pathogenic roles of six Clostridium butyricum strains of human origin. Three strains (CB155-3, CB1002, and CB203-1) isolated from neonatal necrotizing enterocolitis patients and two of three strains (CB19-1 and CB25-2) isolated from healthy newborns led to cecal or crop lesions or both similar to those observed in human neonatal necrotizing enterocolitis: thickening of the cecal wall with gas cysts, hemorrhagic ulcerations, and necrotic areas. The lactose-negative strain (CB46-1) did not develop any lesions. The neuraminidase-producing strain (CB155-3) caused lesions in all monoassociated quails, whereas the other strains caused lesions in 28 to 85% of animals. Removal of dietary lactose suppressed all pathological incidence. These results show that lactose fermentation is a prerequisite in these pathological changes and stress the roles played by both the strain and the host in the expression of C. butyricum enteropathogenicity.

Animals↗
PubMed1988

Histamine distribution in the gastrointestinal wall of germ free and conventional chicken: evidence of the role of the digestive microflora.

The digestive microflora produces a decrease of the mucosal histamine content in the wall of the chicken colon but has no significant incidence in the upper part of the digestive tract. The anatomical and physiological particularities of the chicken digestive tract permitted to observe that wall histamine concentration depends on different factors. Endogenous factors control the wall histamine content in the proventriculus, independantly of the diet and/or of the presence of a microflora. Diet has a specific incidence upon the gastrointestinal wall of the host in the crop and in the colon. The colon microflora decreases the effect of the diet essentially when the chicken are fed a semi synthetic diet. Interactions between the diet and the microflora could induce physiopathological manifestations.

Animals↗
PubMed1988

Production of volatile fatty acids as a result of bacterial interactions in the cecum of gnotobiotic rats and chickens fed a lactose-containing diet.

Volatile fatty acid (VFA) productions from lactose and lactate by a Clostridium butyricum and a Veillonella alcalescens strain, alone or in combination with a Lactobacillus acidophilus strain, were determined both in vitro in culture media and in vivo in the ceca of gnotobiotic animals. Gnotobiotic rats, which possess intestinal lactase, and chickens, which are devoid of it, were used. Both animal species were fed a diet containing 4% lactose. The in vitro results showed that the C. butyricum strain fermented lactose and D-lactic acid to butyric and acetic acids, whereas L-lactic acid was not fermented. The V. alcalescens strain did not ferment lactose and fermented L better than D-lactic acid. The in vivo results showed that high VFA concentrations were obtained in the ceca of chickens either disassociated with V. alcalescens or C. butyricum and Lactobacillus strains or monoassociated with C. butyricum. VFA concentrations in the ceca of rats were low, whatever strain the rats harbored. In addition, an antagonistic effect of the C. butyricum strain against the Lactobacillus strain was evidenced both in rats and chickens. It is suggested that the absence of a host lactase makes the chick a good model for lactose intolerance studies in human newborns.

Anaerobiosis↗
PubMed1985

Experimental cecitis in gnotoxenic chickens monoassociated with Clostridium butyricum strains isolated from patients with neonatal necrotizing enterocolitis.

An animal model for Clostridium butyricum necrotizing cecitis has been developed in axenic chickens inoculated orally between 2 and 50 days of life. Cecitis was obtained with two C. butyricum strains isolated from neonatal necrotizing enterocolitis and not with a Clostridium beijerinckii strain from dairy products; the rate of colonization of the intestinal tract by this strain was lower than that obtained with C. butyricum strains. The clinical findings showed a slow gain in body weight. The cecitis lesions were well developed 3 and 4 weeks after oral inoculation, including enlargement with an increase of the cecum weight-body weight ratio, a marked hyperplasia, congestion, inflammatory infiltrate and pneumatosis of the cecal wall and mesentery, hemorrhage in the lamina propria and submucosa, and ulcerations and necrotic areas in the mucosa. By immunofluorescence and electron microscopy, the bacterial cells were located in the cecal lumen and in necrotic areas of the mucosa. The presence of 4% lactose in the diet seemed to be a prerequisite for the development of cecitis in chickens. A gradual rise of fluorescent antibodies in the sera was observed.

Animals↗
PubMed1983

Amylase production by three Lactobacillus strains isolated from chicken crop.

Three amylolytic Lactobacillus strains designated LEM 220, LEM 207 and LEM 202 were isolated from the chicken crop. They belonged to the subgenus Thermobacterium. Strain LEM 220 resembled Lact. acidophilus. Amylase production was more abundant in cells grown in media containing amylopectin or starch than in media containing glucose or maltose. Optimum pH and temperature of the amylase were 5.5 and 55 degrees C respectively. Hydrolysis of amylopectin gave maltose, maltotriose and small amounts of glucose. Stain LEM 207 also resembled Lact. acidophilus, but differed from strain 220. It had a lower amylase activity. Optimum pH and temperature of the amylase were 6.4 and 40 degrees C, respectively, and hydrolysis of amylopectin gave maltose, maltotriose and carbohydrates higher than maltopentaose. Strain LEM 202 was similar to Lact. vitelinus. It had the lowest amylase activity which was increased only in presence of maltose. Amylase properties were similar to those of LEM 220.

Amylases↗
PubMed1982

Colonization of tissue surfaces in the gastrointestinal tract of gnotobiotic animals by lactobacillus strains.

Eight strains of lactobacilli isolated from conventional mice, rats, fowls, and pigs were tested for their ability to colonize squamous epithelia in the gastrointestinal tracts of gnotobiotic animals. Two of the strains isolated from rodents could colonize the nonsecretory epithelium of the stomach of gnotobiotic rodents, and one strain isolated from a fowl could colonize the crop epithelium of gnotobiotic chickens. The specificity of colonization of squamous epithelia by lactobacilli was demonstrated by these in vivo studies; strains of lactobacilli isolated from rodents could only colonize rodent epithelium; the strain from a fowl could only colonize crop epithelium.

Animals↗
PubMed1981

Energy and protein retention in holoxenic, axenic and gnotoxenic chickens monoassociated with Lactobacillus spp.

1. Axenic, holoxenic and monoxenic chickens (strains LEM 220 or LEM 206 of lactobacilli isolated from the crop of the cockerel) were fed ad libitum on semi-purified diets containing 180 or 200 g protein and 30 g long (LCD) or short (SCD) chain dextrins/kg. Energy and protein retentions were determined from 0 to 3 weeks of age by carcass analysis. 2. Energy retained as a proportion of gross energy intake was only influenced by the microflora in birds receiving 180 g protein/kg and nitrogen retention followed a similar pattern, but differences were less marked: total flora always depressed retentions, but in monoxenic birds the action of the microflora varied with changes in the carbohydrate composition of the diet, the lowest retentions occurring when the diet contained carbohydrates (SCD) which allowed rapid lactate production in the crop.

Animal Feed↗
PubMed1981

The influence of microflora on the breakdown of maize starch granules in the digestive tract of chicken.

Influence of the microflora on the extent of degradation of starch in the chicken digestive tract has been studied by scanning electron microscopy. Axenic (germfree), holoxenic (conventional), and monoxenic (only one germ) chickens inoculated with two strains of lactobacillus (strains 220 and 207) isolated from the crop of the cock were used in these experiments. In vitro starch granules were less hydrolyzed by strain 207 than by strain 220. A more extensive degradation was observed when starch was included in feed. This breakdown resulted in formation of cavities and pin holes in the starch granules. In vivo starch granules in the crop of holoxenic and monoxenic chickens were scarcely damaged and erosion was always superficial. In monoxenic 207 chicken as in holoxenic ones, bacteria were fixed on the crop wall. In feces, the pattern of the breakdown was dependent on the type of animal. These results demonstrated the role of the total microflora in the breakdown of starch and the specific intervention of the two strains of lactobacilli.

Animals↗
PubMed1980

[Role of five Lactobacillus strains on carbohydrate degradation in monoxenic chickens].

Five strains of Lactobacillus were isolated in holoxenic roosters; two of these which had an alpha-amylase were inoculated separately into 5 groups of axenic chickens fed the same diet. Some differences among these 5 groups were noted. Lactobacillus proliferation varied between ten and a thousand-fold, depending on the strain, and for the same strain depending on whether the crop, caecum or faeces was examined. Amylolytic lactobacilli in vivo played a role in starch degradation in various ways related to the specific properties of their amylase. Lactic acid production in the crop was higher with the three strains producing the two lactic acid isomers than with the two strains producing only one of the isomers. Finally, monoxenic caecal digestion was different from that of both the axenic and the holoxenic.

Animals↗
PubMed1979

[Role of the digestive microflora and of the crystalline structure of starch in digestion and dietary efficiency in the chicken. Study of tropical tubers].

The influence of microflora in the utilization of starches, the X ray pattern which was of A or B type, was studied by balances and carcasses analysis with growing axenic or holoxenic chickens, put in isolators. Five tropical tubers were used : Manihot utilissima and Dioscorea dumetorum of A-type, Dioscorea cayenensis and alata and Canna edulis of B-type. They were introduced in isoenergetic (4,460 Kcal/g D.M.) and isoproteic (18 p. 100) diets. The A-type starches are entirely digested (95 p. 100) and the B-type are poorly digested (40-60 p. 100). The first ones induced a better growth than the second. The influence of digestive microflora changes with the two types of tubers used. With A-type starches the microflora lowered the feed intake, the growth and the energy and protein efficiency respectively--25 and--10 p. 100. When the diet included tubers with B-type starches, the low digestibility of starch and the low metabolisable energy in the diets induced poor growth and retentions. The results are discussed in relation with the starch breakdown into glucose, lactic acid and volatile fatty acids.

Animals↗
PubMed1976

[Formation of nitrosamines in the digestive tract].

Nitrosamines are carcinogenic compounds synthetized from amines and nitrites or nitrates, if nitrates in the reaction medium may be reduced to nitrites. Nitrosation is determined in the digestive tract of several species of laboratory animals. Two physiochemical factors appear to determine in vitro nitrosamine formation: the type of amine and the medium pH. The property of secondary amines to nitrosate is inversely related to amine basicity (checked in vivo), and it increases with the medium acidity. In vitro studies show that different types of bacteria can, even at neutral pH, catalyze nitroamine formation from their precursors. However, the role of digestive tract microbial flora in nitrosamine synthesis in the gut cannot be affirmed due to lack of in vivo studies.

Amines↗