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At least 253 records · Page 14Linked to original sources
PubMed1992

[Intraluminal transport of vitamin B12].

Since the existence of vitamin B12 was suggested by Castle in the first few decades of this century, vitamin B12 has been the subject of many studies which have proved the high complexity of it assimilation by the organism. Over the last few years the marked progress in functional digestive exploration methods and the physical and the chemical characteristics of biological molecules have revived the established idea of the vitamin's intraluminal transit. Our recent studies have been concentrated on the bilioduodenopancreatic stage of the vitamin B12 transport. In nature, vitamin B12 is only exceptionally met in its free form it is always associated with a binder. Like a ball being tossed from one player to another, it moves between binders. Alimentary vitamin B12 released from its protein complexes by culinary preparation and gastric secretions, is combined with haptocorrin. Around the duodenum the transfer of B12 on intrinsic factor is due to partial degradation of haptocorrin by pancreatic enzymes and intraluminal pH balance. This combined with intrinsic factor the vitamin can be caught by the ileal receptor. The partial degradation haptocorrin joins vitamin B12 analogs from excreted bile or synthesized by the intestinal microorganisms.

Biological Transport↗
PubMed2006

Natural antibodies to endotoxin in experimental and clinical oncology.

The studies on natural endotoxin immunity, carried out at Preventive Immunology Laboratory of Institute of Oncology of Vilnius University have shown that the natural immune functions of both immunostimulated and immunosuppressed organisms are closely related to IgM class natural antibodies (IgMNA) to the enterobacterial common antigen (ECA) from membranes of intestinal microorganisms, i.e. endogenous or spontaneous antibodies to endotoxin. With aging, when cellular immunity functions deteriorate, the level of these NA to endotoxin (NAE) in blood serum increases. The population level of NAE is enhanced by carcinogens and chemotherapeutic drugs in dependence from their doses and downregulated by tobacco smoking, alcohol consumption, exposure to environmental pollution, professional exposure to harmful agents, and chronic diseases. IgMNAE reflects enhancement of the natural immune functions of the organism on the background of the suppressed functions of classic cellular immunity and suits well to our new conception of elucidating the natural compensatory responses of immune homeostasis related to immune response to endotoxin.

Alcohol Drinking↗
PubMedDate not supplied

Diastereoisomeric glucuronides of oxazepam. Isolation and stereoselective enzymic hydrolysis.

Oxazepam glucuronide isolated from swine urine by previously published methods was separated into its diastereoisomers by ion-exchange chromatography on a preparative scale. Quantitative high-performance liquid chromatography was used to monitor the separation. The two isomers were obtained in analytically pure form and then characterized by elemental analysis, oxazepam content, mass spectrometry, ultraviolet spectroscopy, optical rotation and optical rotatory dispersion-circular dichroism. The latter permitted the assignment of the dextrorotatory and the levorotatory isomers to the (S)- and (R)- configurations, respectively. Rates of enzymic hydrolysis depend on the configuration of the substrate as well as on the enzyme preparation used. Rate of cleavage was highest with the (S)-(+)-glucuronide and beta-glucuronidase from Escherichia coli. This enzyme possesses the highest degree of stereoselectivity; it hydrolyzes the (S)-(+)-isomer more than 400 times faster than the (R)-(-)-form. Bovine liver glucuronidase is less stereoselective, whereas glucuronidase preparations of molluscan origin exhibit little stereoselectivity. The ready hydrolysis of one of the glucuronides by an enzyme from an intestinal microorganism may play a role in the enterohepatic circulation of oxazepam.

Animals↗
PubMed1981

Gallstone formation in guinea pigs under different dietary conditions. Effect of vitamin C on bile acid pattern.

Guinea pigs formed gallstones when fed chow supplemented with cholesterol and cholic acid. Although the stones contained little or no cholesterol the changes in biliary bile acid and lipid composition were similar to those observed in other rodents under conditions of cholesterol gallstone formation. Addition of cholestyramine to chow had a midly lithogenic effect. Hypovitaminosis C in animals given cholesterol and cholic acid resulted in an increase of the cholesterol content of the gallstones. The composition of biliary bile acids was markedly changed. Reductive formation of deoxycholic acid decreased and oxidative formation of ketonic bile acid increased. The results show that vitamin C may influence the redox state of the intestinal microorganisms microorganisms responsible for these conversions.

Animals↗
PubMed1996

15 alpha-hydroxylation of a bile acid analogue, sodium 3 alpha,7 alpha-dihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate in the hamster.

The metabolism of 3 alpha,7 alpha-dihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate (bishomoCDC-sul), the sulfonate analogue of bishomochenodeoxycholic acid, and its effect on biliary bile acid composition were studied during chronic administration in the hamster. After oral administration of radiolabeled bishomoCDC-sul, more than 80% of the radioactivity was excreted into the feces within 7 days, both as the unchanged sulfonate (38.5%) and two more polar metabolites (50.0% and 11.5%). The half time of the fecal excretion was 1.6 days. In gallbladder bile, the unchanged sulfonate and its major metabolite accounted for 19.1% and 19.8% of total bile acids, respectively. In another experiment, hamsters were fed bishomoCDC-sul with antibiotics to evaluate the site of biotransformation. Even when the number of intestinal microorganisms was greatly reduced, the same three metabolites were found in the feces: bishomoCDC-sul (44.0%) and the two polar metabolites (30.8% and 25.1%). The major metabolite was isolated from feces of the hamsters fed bishomoCDC-sul without antibiotics. Its chemical structure was identified by mass spectrometry and nuclear magnetic resonance spectroscopy as the 15 alpha-hydroxylated derivative, namely sodium 3 alpha,7 alpha,15 alpha-trihydroxy-25,26-bishomo-5 beta-cholane-26-sulfonate. These results indicate that after oral administration, the sulfonate analogue of bishomochenodeoxycholic acid underwent enterohepatic circulation like a natural bile acid and was transformed, in part, into the 15 alpha-hydroxylated derivative and another more polar metabolite in the liver of hamsters. There was no evidence that bishomoCDC-sul was dehydroxylated to a lithocholic acid analogue during enterohepatic cycling.

Animals↗
PubMed2001

Comparison of translocation of different types of microorganisms from the intestinal tract of burned mice.

The aim of this study was to compare the ability of various microorganisms to translocate from the intestine to the mesenteric lymph nodes (MLNs), liver, and spleen in a burned mouse model. Balb/c mice were gavaged with 1 x 10(9) or 1 x 10(10) of one of 11 different microorganisms. All animals were then given a 20% burn. Survival after 10 days showed no significant difference between any of the groups at the 10(10) dose. At the 10(9) dose, significantly higher survival rates were found in three of the 11 strains. Microbial translocation (gavage of 10(10) 111In-labeled organisms) and host's ability to kill translocated bacteria (viable bacteria in tissues) were measured followed by burn injury and sacrifice four hours later. Translocation and killing of Staphylococcus epidermidis and Escherichia coli was high in the MLNs compared with all other groups but translocation was lower to the liver. Klebsiella, Pseudomonas, and Serratia translocated more evenly to all the tissues. However, these groups showed very high clearance of bacteria in the liver and spleen except for Klebsiella and one strain of Pseudomonas in the spleen. Candida showed poor translocation to all of the tissues and high clearance. It is concluded that various strains of bacteria translocate from the intestine to a similar degree after injury, but the tissues to which they translocate and the rate at which they are killed are somewhat strain dependent.

Animals↗
PubMedDate not supplied

[Characteristics of microorganisms colonizing human intestine].

Introduction of novel methods of microbial diagnostics has considerably broadened our conceptions on the qualitative and quantitative variety of microorganisms inhabiting human gastrointestinal tract. In this review morphological and functional properties of obligate anaerobic bacteria (bifidobacteria, lactobacilli, eubacteria, peptostreptococci, clostridia, bacteroids, fusobacteria) and facultative anaerobic microorganisms (enterobacteria, staphylococci, streptococci, yeast-like fungi of the genus Candida) capable of colonizing human intestine are briefly characterized.

Bacteria, Anaerobic↗
PubMed1997

[The reaction of the lymphoid patches in the small intestine to different microorganism counts in the drinking water].

In the experiment, performed in 3-months-old albino Wistar rats, the response of small intestine lymphoid patches to continuous action of drinking water with different content of opportunistic microorganisms was studied histologically and morphometrically. Changes of lymphoid nodule number and diameter and of correlation of the organ cross section areas occupied by lymphoid nodules and diffuse internodular lymphoid tissue which is dependent on microbe concentration in drinking water was demonstrated.

Animals↗
PubMed1999

Uptake and transport of intestinal macromolecules and microorganisms by M cells in Peyer's patches--a personal and historical perspective.

Dr Kenzaburo Kumagai identified dome epithelium of intestinal lymphoid tissues as a site of uptake for mycobacteria in 1922, but he saw this only as a possible initiation point for intestinal tuberculosis and abandoned even that premise as non-specific, after finding that sheep red blood cells were also taken up. When development of ultrastructural techniques in 1972 permitted identification of M cells with phagocytic capabilities, harboring migrating lymphoid cells in the specialized epithelium over Peyer's patches, these patches remained anatomic curiosities with no recognized physiologic role. These structural observations of M cells and of intestinal lymphoid tissues stimulated functional, structural and molecular biologic investigations which now provide the basis for many of our current concepts of mucosal immunology and the roles of M cells in initiation of defensive immune responses.

Animals↗