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PubMed1962

Urinary calculi in germfree rats.

In a colony of germfree rats 50 per cent of the males had urinary calculi composed of calcium citrate and calcium oxalate. Genetically closely related conventional animals on the same sterilized diet did not present a single case of stone formation. The tendency to calculus formation disappeared when germfree animals were contaminated with the intestinal flora from conventional rats. The calculus formation can readily be explained by the high calcium, high citrate, and high pH of the urine. This pattern was changed to that of conventional rats when the germfree rats were infected with intestinal microorganisms.

Animals↗
PubMed2006

Lactobacillus delbrueckii subsp lactis strain CIDCA 133 inhibits nitrate reductase activity of Escherichia coli.

The aim of the present work was to investigate the effect of strain CIDCA 133 on the nitrate reductase activity of a non-pathogenic Escherichia coli strain. Suspensions containing different ratios of the strains under study were coincubated in MRS or MRS without glucose. In some experiments lactobacilli were killed by UV treatment. The nitrate reductase activity was determined by using a diazotization reaction for nitrite. Presence of live lactobacilli leads to a dose-response diminution in the specific nitrate reductase of E. coli even when no acidification occurred. Killing of lactobacilli by UV treatment completely abolished the anti-nitrate reductase effect. In addition, the effect was only partially observed with filtered spent culture supernatants of lactobacilli. Lactobacillus delbrueckii subsp lactis strain CIDCA 133 is able to antagonize the nitrate reductase activity of E. coli. This effect is neither due to a diminution of the viability of E. coli nor is depending on the acidification of the medium by the lactobacilli. Viability is needed for maximal anti-nitrate reductase activity. Modulation of undesirable enzymatic activities of intestinal microorganisms by means of selected microorganisms constitutes a further insight on the mechanisms by which probiotics lead to beneficial effects. Administration of probiotic strains able to modulate microbial intestinal activities could lead to a protection of the host against harmful effects of some members of the intestinal microflora.

Colony Count, Microbial↗
PubMed1989

[Preliminary study on intestinal microflora in patients with cirrhosis].

Intestinal microflora were studied in 62 patients with cirrhosis, 14 with hepatitis and 30 normal subjects. The fecal anaerobes, total viable organisms, E.coli, enterococcus, bifidobacterium, lactobacillus and clostridium were significantly greater in number in cirrhotic patients than in normal subjects and hepatitis. Significant increase in fecal enterococcus and clostridium was observed in the patients recently recovered from hepatic coma as compared with the patients without hepatic coma. Bifidobacterium was increased in cirrhotic patients between patients with or without LLT (+). These data suggest that there was a tendency of the intestinal microorganisms to be increased in cirrhotic patients and the existence of possible relationship between the severity of liver function impairment and quantity of intestinal flora.

Adult↗
PubMed2005

Isolation and characterization of enteric bacteria from the hindgut of Formosan termite.

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is an aggressive, invasive termite species that has caused billions of dollars of damage across the United States for the past 50 years. Termites depend on intestinal microorganisms for cellulose digestion. Symbiotic microorganisms in the termite gut play key physiological functions such as cellulose and hemicellulose digestion, acetogenesis, hydrogenesis, methanogenesis, sulfate reduction, and nitrogen fixation. Additionally, intestinal microbes create suitable conditions for symbiotic protozoans through the production of nutrients and the maintenance of the pH and the anaerobic conditions in the gut. Although extensive research has been done on the symbiotic relationship of these termites and the microbes found in its gut, there is little information available on the role of facultative anaerobes in the gut. We isolated four enteric bacteria from the hindgut of Formosan subterranean termite, C. formosanus. All isolates were facultative anaerobes and G-. The isolates were identified as Serratia marcescens, Enterobacter aerogens, Enterobacter cloacae, and Citrobacter farmeri by using BIOLOG assay and fatty acid methyl ester analysis (FAME). Each isolate was characterized using sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and biochemical study. This is the first report on the presence of facultative microbes in termite gut. Results of this first study on facultative microbes in the termite gut indicate that the role of facultative organisms in the Formosan termite gut may be to scavenge oxygen and create anaerobic conditions for the anaerobic microorganisms, which are essential for digestion of cellulose consumed by the termite.

Acyltransferases↗
PubMed2003

Commensal bacteria make a difference.

Nowhere is the relationship between microorganisms and eukaryotes as diverse, intimate and clinically relevant as in the gastrointestinal tract. An estimated 500-1000 mostly anaerobic species reside in the intestine, approaching enormous densities of 10(11)-10(12) organisms per gram colon content. The commensal interactions between intestinal microorganisms and animal hosts have been difficult to study in the past because of the diversity of microorganisms involved and because of the lack of culturability that accompanies many microbial consortia. However, recent work has provided new insights into these interactions.

Anaerobiosis↗
PubMed1992

The reduction of azo dyes by the intestinal microflora.

Azo dyes are widely used in the textile, printing, paper manufacturing, pharmaceutical, and food industries and also in research laboratories. When these compounds either inadvertently or by design enter the body through ingestion, they are metabolized to aromatic amines by intestinal microorganisms. Reductive enzymes in the liver can also catalyze the reductive cleavage of the azo linkage to produce aromatic amines. However, evidence indicates that the intestinal microbial azoreductase may be more important than the liver enzymes in azo reduction. In this article, we examine the significance of the capacity of intestinal bacteria to reduce azo dyes and the conditions of azo reduction. Many azo dyes, such as Acid Yellow, Amaranth, Azodisalicylate, Chicago Sky Blue, Congo Red, Direct Black 38, Direct Blue 6, Direct Blue 15, Direct Brown 95, Fast Yellow, Lithol Red, Methyl Orange, Methyl Red, Methyl Yellow, Naphthalene Fast Orange 2G, Neoprontosil, New Coccine, Orange II, Phenylazo-2-naphthol, Ponceau 3R, Ponceau SX, Red 2G, Red 10B, Salicylazosulphapyridine, Sunset Yellow, Tartrazine, and Trypan Blue, are included in this article. A wide variety of anaerobic bacteria isolated from caecal or fecal contents from experimental animals and humans have the ability to cleave the azo linkage(s) to produce aromatic amines. Azoreductase(s) catalyze these reactions and have been found to be oxygen sensitive and to require flavins for optimal activity. The azoreductase activity in a variety of intestinal preparations was affected by various dietary factors such as cellulose, proteins, fibers, antibiotics, or supplementation with live cultures of lactobacilli.

Animals↗
PubMed2000

Difructose anhydrides: their mass-production and physiological functions.

Difructose anhydrides (DFAs) are the smallest cyclic disaccharides consisting of two fructose residues, and are expected to have novel physiological functions from their unique structures and properties. For mass-production of alpha-D-fructofuranose-beta-D-fructofuranose-2',1:2,3'-dianhydride (DFA III) and beta-D-fructofuranose-beta-D-fructofuranose-2',6:2,6'-dianhydride (DFA IV), Arthrobacter sp. H65-7 and A. nicotinovorans GS-9 were selected as the best producers of inulase II, which produced DFA III from inulin and LFTase, which produced DFA IV from levan. The enzymes were purified and their genes were subsequently cloned and expressed in E. coli at higher levels than in the original bacteria. Thus, it became possible to provide a large amount of DFA III and DFA IV for evaluating their physiological properties. DFA III and DFA IV have half the sweetness of sucrose, but cannot be digested by the digestive system of rats. Their use by the intestinal microorganisms was observed in vivo even though their assimilation could not be detected in vitro. This implied that they were degraded by an unknown system in the intestine. It was also found that they affected calcium absorption mainly in the small intestine through mechanisms different from the known stimulants such as fructooligosaccharides and raffinose.

Animals↗
PubMed1999

Dose response models for infectious gastroenteritis.

When pathogenic microorganisms enter the human body via ingestion with food or drinking water, they encounter a system of barriers mounted by the host. In order to reach parts of the intestinal tract that are suitable for growth and attachment, each of the barriers must be overcome successfully. The present view on infection states that at least one of the ingested pathogens must survive to start colonization. This is the basis for dose response models, used for quantitative risk assessment. In this paper, the usefulness of the Beta Poisson model for multiple barriers is corroborated. Infection is associated with the presence of elevated numbers of reproducing pathogens in the intestinal tract. This does not necessarily imply illness symptoms: when intestinal microorganisms engage in damaging activities, this may lead to illness symptoms. At the same time, these activities probably elicit defensive measures from the host, promoting the removal of pathogens and terminating infection. The duration of the period of colonization reflects the balance between the colonization potential of pathogens and the strength of host defenses. Starting from the assumption that during infection the host has a certain hazard of becoming ill, a simple dose response relation for acute gastroenteritis is developed. With the use of literature data from volunteer experiments, we show that examples can be found for three possible alternatives: an increase in the probability of illness with increasing dose, a decrease with higher doses, and a probability of illness (given infection) independent of the ingested dose. These alternatives may reflect different modes of interaction between pathogens and host.

Animals↗
PubMedDate not supplied

Hepatic macromolecular covalent binding and intestinal disposition of [14C]dinitrotoluenes.

The covalent binding to hepatic RNA, DNA, and protein of a highly genotoxic dinitrotoluene (DNT) isomer (2,6-DNT) was compared with that of a less genotoxic DNT isomer (2,4-DNT) after oral administration to male Fischer-344 rats. Covalent binding to each macromolecular species was proportional to dose (10 or 35 mg/kg) for each isomer, but that due to 2,6-DNT was always 2-5-fold higher than that due to 2,4-DNT. There was no selectivity of either isomer for any macromolecule. The time course of appearance and disappearance of covalently bound material was similar regardless of isomer or dose administered. Little covalently bound material was present until 8 h after the dose. Covalent binding peaked between 12 and 24 h and then slowly declined. The half-lives of covalently bound material were independent of the isomer administered, ranging from 2.9 to 5.0 d for RNA and protein and from 5.1 to 7.9 d for DNA. Both isomers disappeared from the small intestine rapidly, and covalent binding to hepatic macromolecules became significant only after the isomeric dinitrobenzyl alcohol glucuronides had appeared in the small intestine. The concentration of alcohol glucuronides in the intestine declined prior to peak covalent binding in the liver. The data suggest that covalent binding to hepatic macromolecules qualitatively reflects the differences in genotoxicities between the two isomers. The time course of intestinal disposition of the two isomers supports previous reports that suggest that activation of both isomers requires oxidation to the corresponding benzyl alcohol, glucuronidation, excretion in the bile, deconjugation, and further metabolism by intestinal microorganisms, followed by reabsorption.

Animals↗
PubMed1981

Intestinal synthesis and absorption of vitamin B-12 in channel catfish.

A feeding experiment conducted in a controlled environment and using a vitamin B12-deficient, but otherwise nutritionally complete, purified diet revealed that intestinal microorganisms in channel catfish synthesized approximately 1.4 ng of vitamin B12 per gram of bodyweight per day. Removal of cobalt from the diet or supplementation with an antibiotic (succinylsulfathiazole) significantly reduced the rate of intestinal synthesis and liver stores of vitamin B12. Radiolabeled vitamin B12 in the blood, liver, kidneys, and spleen of fish fed 60Co in the diet indicated that the intestinally synthesized vitamin was absorbed by the fish. The primary route of absorption was directly from the digestive tract into the blood because coprophagy was prevented in the rearing aquariums and the amount of vitamin B12 dissolved in the aquarium water was too low for gill absorption. Dietary supplementation of vitamin B12 was not necessary for normal growth and erythrocyte formation in channel catfish in a 24-week feeding period. A longer period, however, may have caused a vitamin deficiency since liver-stored vitamin B 12 decreased between the 2nd and 24th weeks.

Animals↗
PubMed1989

Pharmacokinetics of acarbose. Part I: Absorption, concentration in plasma, metabolism and excretion after single administration of [14C]acarbose to rats, dogs and man.

The absorption, disposition, metabolism, and excretion of acarbose (O-4,6-dideoxy-4-[[(1S, 4R, 5S, 6S)-4,5,6-trihydroxy-3- (hydroxymethyl)-2- cyclohexen-1-yl]amino]-a-D-glucopyranosyl- (1----4)-O-a-D-glucopyranosyl- (1----4) -D-glucopyranose, Bay g 5421) have been studied following a single administration of the 14C-labelled compound to rats and dogs via different routes (intravenous, oral, intraduodenal) in the dose range of 2-200 mg.kg-1 as well as to man in a single oral dose of 200 mg. After intravenous administration [14C]acarbose was eliminated rapidly and completely via the renal route. There was no indication for a systemic metabolization of [14C]acarbose. The (renal) clearance for [14C]acarbose was in the range of the glomerular filtration rate. After oral administration [14C]acarbose was very poorly absorbed (1-2% of dose in rats and man and 4% in dogs). Additionally, up to 35% of the radioactivity of [14C]acarbose were absorbed after degradation by digestive enzymes and/or intestinal microorganisms. The delayed and biphasic absorption of the radioactivity strongly influenced the plasma concentration vs time profiles of total radioactivity. Maximum concentrations dependent on the degree of microbial degradation (dog less than rat, man) and on the intestinal transit time were reached at 1.2 h (dogs), 8 h (rats) and 14-24 h (man). The excretion of the radioactivity absorbed occurred rapidly and completely mostly via the renal route.(ABSTRACT TRUNCATED AT 250 WORDS)

Acarbose↗
PubMed2000

[Basic studies on the utility of ursodeoxycholic acid derivatives for clinical medicine].

The aim of this study was to determine whether the derivatives of ursodeoxycholic acid (UDCA) are useful compounds for clinical medicine. 1-1) A conjugate (5-ASA-UDCA monophosphate) of UDCA monophosphate with 5-aminosalicylic acid (5-ASA) was newly synthesized, and basic studies on this compound were carried out. This compound was efficiently deconjugated by cholylglycine hydrolase (CGH) to release 5-ASA, whereas it was completely resistant to deconjugation by pancreatic and intestinal mucosal enzymes. In animal experiments, the urinary excretion of N-acetyl-5-ASA (Ac-5ASA) was measured for 24 h following the oral administration of 20 mg of 5-ASA-UDCA monophosphate. Control rats excreted 276.3 +/- 89.0 micrograms (mean +/- S.E.) of Ac-5ASA whereas rats with intestinal bacterial overgrowth excreted more (1224.1 +/- 231.5 micrograms; p < 0.01). These basic studies indicate that this compound is likely to offer a simple method for the evaluation of intestinal microorganisms without the use of radioisotopes or expensive, special apparatus. 1-2) The disulphate ester of ursodeoxycholyl-p-aminobenzoic acid (PABA-UDCA) was synthesized and compared with PABA-UDCA for its use in the detection of intestinal bacteria. This compound, PABA-UDCA disulphate, had characters in common with PABA-UDCA in that it was deconjugated by CGH to release free PABA. Further, in rat experiments the urinary excretion of PABA was measured for 6 h after oral administration of 15 mg PABA-UDCA disulphate. Ten control rats excreted 188.2 +/- 13.6 micrograms (mean +/- S.E.) of PABA; 10 rats with an intestinal stagnantloop excreted more (530.1 +/- 30.1 micrograms; p < 0.001): whereas 10 rats in each of three groups pretreated with oral administration of various antibiotics excreted less. PABA-UDCA disulphate is a single pass type substance in the gut and its oral administration test reflects the sum of the activities of bacteria in the small intestine and colon. From the results the obtained PABA-UDCA disulphate was considered a good material to detect intestinal bacteria. 2) A conjugate (Lys-UDCA) of UDCA with L-lysine was newly synthesized. In the incubation experiments with plasma, homogenates of the liver and small intestine, various pancreatic enzymes and CGH, Lys-UDCA was deconjugated by carboxypeptidases B and CGH. In the experiment using rodent everted gut sac, Lys-UDCA was actively absorbed from the terminal ileum. Lys-UDCA was recovered well in the bile after intravenous or intraileal administration of Lys-UDCA in biliary fistula rat. These data suggest that Lys-UDCA is a good prodrug of UDCA for intravenous administration. 3) A novel calcium-chelating agent, N"-ursodeoxycholyl-diethylenetriamine-N,N,N'-triacetic acid (UDCA-DTTA), was synthesized to study its ability to dissolve calcified gallstones. In the presence of the agent, sliced human gallstone with a composition of more than 50% calcium bilirubinate was thoroughly dissolved, indicating that calcium bilirubinate was dissolved from the gallstone. The ability to dissolve calcium was comparable to that of EDTA. However, the laminar structure of the sliced gallstone did not disappear in the presence of EDTA, whereas the structure disappeared in the presence of UDCA-DTTA. These results indicate that UDCA-DTTA is an interesting compound as a parent substance for developing a prodrug for an oral or intravenous agent to dissolve calcium-containing gallstones.

Animals↗
PubMed2003

Immunomodulatory consequences of oral administration of Lactobacillus rhamnosus strain GG in healthy volunteers.

Probiotic microorganisms, especially lactic acid bacteria, are effective in the treatment of infectious diarrhoeal diseases and experimental colitis. Although the mechanisms by which these organisms exert their anti-inflammatory effects are largely unknown, immunomodulating effects are suggested. The objective of this study was to examine the effect of a 5-week oral administration of Lactobacillus rhamnosus subspecies GG (Lb. GG) on the cellular immune response to intestinal microorganisms in ten healthy volunteers. Peripheral blood cells (PB) were stimulated with either 'self' or 'non-self' preparations of faecal samples and isolated Bacteroides fragilis group-organisms (Bfg) or Escherichia coli (Esch. coli), and pro- and anti-inflammatory cytokines (IL-10, IL-4, IL-6, IFN-gamma, TNF-alpha) were measured in the culture supernatant. CD4+ T-lymphocyte activation was determined by measurement of intracellular ATP following lysis of the cells. The activational response of CD4+ T-lymphocytes towards isolated and heat-inactivated intestinal organisms was increased after the probiotic treatment. Additionally, TNF-alpha, IL-6 and in part IFN-gamma cytokine secretion by PB cells following stimulation with whole stool preparations and single members of the flora was significantly decreased, whereas the IL-10 and in part IL-4 cytokine secretion was increased at the end of the study. In contrast, the activational response of CD4+ T-lymphocytes following stimulation with whole 'non-self' intestinal flora was higher than by 'self' intestinal flora, but both responses showed a trend towards a reduction at the end of the study. This study documents a direct effect by Lb. GG on the cellular immune system of healthy volunteers and offers a promising tool to investigate systemic immunomodulation due to oral administration of probiotic microorganisms.

Adult↗
PubMed1996

Resistance of the normal human microflora to mercury and antimicrobials after exposure to mercury from dental amalgam fillings.

The concentrations of mercury in saliva and feces and the resistance pattern of the gastrointestinal microflora were investigated for 20 subjects. Ten patients, with a mean number of 19 amalgam surfaces, had all amalgam fillings removed during one dental session. Ten subjects without amalgam fillings served as a control group. Saliva and fecal samples were collected before amalgam removal and 2, 7, 14, and 60 days afterward. Mercury levels in saliva and feces correlated significantly with the number of amalgam surfaces. No differences in the resistance pattern of the oral microflora were detected between the two groups. In the amalgam group there was an increase in the relative number of intestinal microorganisms resistant to mercury, ampicillin, cefoxitin, erythromycin, and clindamycin on days 7-14. This was not statistically significant in light of the normal variations of the control group. A significant correlation between the prevalence of mercury resistance and multiple antimicrobial resistance in intestinal bacterial strains was observed.

Adolescent↗
PubMed2004

Soyasaponin I and sapongenol B have limited absorption by Caco-2 intestinal cells and limited bioavailability in women.

A human study was conducted to evaluate soyasaponin bioavailability in humans. Eight healthy women ingested a single dose of concentrated soy extract containing 434 micromol of group B soyasaponins, the predominant form of soyasaponins in soybeans. Neither soyasaponins nor their metabolites were detected in a 24-h urine collection. Soyasapogenol B, a major metabolite of group B soyasaponins, was found (36.3 +/- 10.2 micromol) in a 5-d fecal collection but no group B soyasaponins were detected. A human colon cancer Caco-2 cell model was used to evaluate the absorbability of soyasaponins at the mucosal level. The mucosal transfers of soyasaponin I and soyasapogenol B were 0.5-2.9 and 0.2-0.8%, respectively, after 4-h incubation on the Caco-2 monolayer. The apical to basolateral absorptions of soyasaponin I and soyasapogenol B were low with P(app) of 0.9 to 3.6 x 10(-6) and 0.3 to 0.6 x 10(-6) cm/s, respectively. The transport rate and cell uptake of soyasaponin I were saturable and concentration-independent. In contrast, soyasapogenol B was taken up by Caco-2 cells in a concentration-dependent manner. Soyasaponin I had no apparent cytotoxic effect on Caco-2 cells at concentrations up to 3 mmol/L, whereas soyasapogenol B at 1 mmol/L or more significantly reduced cell viability. Therefore, ingested soyasaponins have low absorbability in human intestinal cells and seem to be metabolized to soyasapogenol B by human intestinal microorganisms in vivo and excreted in the feces.

Administration, Oral↗
PubMed1990

Hydrolysis of pyridoxine-5'-beta-D-glucoside by a broad-specificity beta-glucosidase from mammalian tissues.

Research was conducted to evaluate the ability of a broad-specificity beta-glucosidase in mammalian tissues to catalyze the hydrolytic release of free pyridoxine from pyridoxine-5'-beta-D-glucoside, a naturally occurring form of vitamin B6 in plant-derived foods. Activity was detected in liver and intestinal mucosa using tritiated pyridoxine glucoside as a substrate. In the rat and guinea pig, enzyme activity was greater in intestine than in liver or kidney while even greater activity was detected in human intestinal tissue. Reaction rates were, however, low in all tissues. Hydrolysis of the synthetic substrate 4-methylumbelliferyl-beta-D-glucoside was also greatest in intestinal tissue. The characteristics of the enzymatic hydrolysis of pyridoxine glucoside to pyridoxine included: (i) most activity in the soluble tissue fraction, (ii) a pH optimum of approximately 6.0, and (iii) inhibition caused by the addition of sodium taurocholate. These characteristics are very similar to those of the broad-specificity beta-glucosidase in mammalian tissues with respect to the hydrolysis of a variety of naturally occurring and synthetic substrates. The apparent Km was greater than 2 mM for pyridoxine glucoside hydrolysis by intestinal preparations of each species, which is much greater than expected intestinal concentrations derived from dietary sources. In vivo studies have indicated that the intestine is involved in the metabolic utilization of dietary pyridoxine glucoside. The results observed here suggest that an alternate process, possibly involving intestinal microorganisms, may also be involved in the in vivo hydrolysis of pyridoxine glucoside.

Animals↗
PubMed2001

Impact of bacteria in dairy products and of the intestinal microflora on the genotoxic and carcinogenic effects of heterocyclic aromatic amines.

This article gives a short overview on the present state of knowledge of the effects of the intestinal microflora on the health hazards of heterocyclic aromatic amines (HAs). Results of single cell gel electrophoresis assays with conventional, germ free and human flora associated rats indicate that the presence of intestinal microorganisms strongly enhances the induction of DNA-damage in colon and liver cells by IQ. Furthermore, it was found that supplementation of the feed with Lactobacilli attenuates the induction of colon cancer by this same amine. These recent findings suggest that the intestinal microflora and lactic acid bacilli in dairy products strongly affect the health risks of HAs. Nevertheless, most previous experiments with HAs focused on the involvement of mammalian enzymes in the biotransformation of these compounds and only a few articles are available which concern interactions of bacteria with HAs. Some of these studies suggested that the formation of directly mutagenic hydroxy-metabolites of the amines by fecal bacteria might be an important activation pathway but it turned out that the hydroxy-derivative of IQ is not genotoxic in mammalian cells and does not cause colon cancer in laboratory rodents. There is some evidence that hydrolysis of HA-metabolites by bacterial ss-glucuronidase might play a role in the activation of HAs but experimental data are scarce and no firm conclusions can be drawn at present. The most important detoxification mechanism appears to be the direct binding of the HAs to the cell walls of certain bacterial strains contained in fermented foods. It was shown that these effects do also take place under physiologically relevant conditions. Overall, it seems that intestinal bacteria play a key role in the activation and detoxification of HAs which has been an area of research long ignored. The elucidation of these mechanisms may enable the development of biomarkers for colon cancer risk and nutritional strategies of protection.

Amines↗