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At least 1,135 records · Page 63Linked to original sources
PubMed1988

Potential impact of colonic irrigation on the indigenous intestinal microflora.

Under normal physiological conditions, the indigenous intestinal microflora is stable. The stability protects the host from colonization of nonindigenous microorganisms, including pathogens. Indigenous microorganisms capable of producing toxins are held in check by competing microflora, but any accidentally absorbed toxins are efficiently detoxified by the liver in the absence of hepatic pathology. Antibiotics are known to disrupt the normal flora leading to increased susceptibility to infection with other members of the normal flora or to toxins produced by them. It is possible that mechanical disruption of the flora by colonic irrigation could have a similar effect. Inadequately disinfected colonic irrigation machines have been the source of documented iatrogenic infection with Entamoeba histolytica. The potential for iatrogenic transmission of AIDS in a similar fashion must be considered.

Colon↗
PubMed1987

Impact of cefaclor on the normal human oropharyngeal and intestinal microflora.

Cefaclor was given orally in doses of 250 mg every 8 h for 7 days to 10 volunteers. Saliva and faecal specimens were taken up to 16 days for cultivation of aerobic and anaerobic microorganisms and for assay of cefaclor. Cefaclor was not detected in saliva or faeces. In the oropharynx only minor changes in the anaerobic part of the microflora were observed. The microflora was normalized within 1 week after the administration of cefaclor had stopped. The aerobic intestinal microflora was unchanged during and after cefaclor administration while a minor impact on the anaerobic intestinal microflora was observed. The anaerobic intestinal flora returned to its normal state within 1 week. No new colonization with cefaclor resistant microorganisms were observed and no side effects were registered during the investigation period.

Adult↗
PubMed2004

Assessing survival of dairy propionibacteria in gastrointestinal conditions and adherence to intestinal epithelia.

The genus Propionibacterium consists of two principal groups, cutaneous and classical or dairy. Cutaneous species are predominant members of the microbial population of human skin and have also been isolated from the feces of humans and other vertebrate animals. They are often considered opportunistic organisms and have been occasionally associated with infections in humans. Dairy propionibacteria are microorganisms extensively used in the industry for manufacture of Swiss-type cheeses and biological production of propionic acid and vitamin B12. They can be isolated from soil, vegetables, silage, raw milk, and dairy products such as kefir and different cheeses with "eyes."In the last decade, several studies have demonstrated probiotic properties for members of the genus Propionibacterium. The effects claimed are based on the production of bacteriocins, vitamins, stimulation of growth of other colonic bacteria like bifidobacteria, beneficial modification of the composition and metabolic activities of the intestinal microflora, immunomodulation, and antimutagenic activity. It is thought that to produce many of these health benefits, the probiotic microorganisms must be able to survive the transit through the hostile conditions of the gastrointestinal tract (GIT) and remain at high levels in the intestine, avoiding removal by peristaltic contractions of the gut. In this sense, microorganisms with a short generation time or the ability to adhere to the intestinal mucosa will survive for prolonged periods in the body of the host. Therefore, two desirable properties for probiotic microorganisms are (1) resistance to gastric acidity, bile, and pancreatic enzymes; and (2) adhesion ability to mucosal surfaces. Dairy bacteria are traditionally not considered to persist as normal inhabitants of the human intestinal tract. Therefore, survival under GIT conditions and adherence are important properties to be considered, and tests to study them would be useful tools. In the present chapter we describe the methods used in our laboratory to assess survival, metabolic activity, and adhesion of dairy propionibacteria to intestinal epithelial cells after gastrointestinal digestion.

Animals↗
PubMed1989

[The effect of enterococci on normalizing the intestinal microflora in experimental dysbacteriosis].

The normal microflora of the intestine produces essential influence on the vital activity of the host. The exposure of the body to the action of different unfavorable factors (roentgen radiation, the administration of antibiotics, Salmonella infection, etc) results in changes in the normal microflora of the gastrointestinal tract. This work was aimed at the study of the influence of Streptococcus faecium YDC-48 on the intestinal microflora of mice in experimental (chemotherapeutic, postirradiation) dysbacteriosis and Salmonella infection. The effect of the oral administration of S. faecium YDC-48 on the correction of the intestinal microflora of mice in cases of dysbacteriosis etiology was studied. The intragastric administration of S. faecium YDC-48 was found to induce an increase in the level of lactobacterin and a decrease in the number of opportunistic microorganisms in chemotherapeutic and postirradiation dysbacteriosis. The oral administration of S. faecium YDC-48 decreased the manifestations of intestinal dysbacteriosis in experimental Salmonella infection. The possibility of developing a preparation on the basis of S. faecium YDC-48, a representative of normal intestinal microflora, is discussed.

Ampicillin↗
PubMed2004

Establishment of Mycobacterium avium subsp. paratuberculosis infection in the intestine of ruminants.

Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) is the cause of paratuberculosis, which is a chronic enteritis of ruminants characterized by granulomatous inflammation. The transmission of the infection is mainly by faecal contaminated feed. The bacteria are transported from the intestinal lumen into the intestinal wall via M cells, which overlie the domes of Peyer's patches. It is proposed that integrin receptors on the apical surface of M cells bind fibronectin-opsonized bacteria, facilitating phagocytosis by these cells. After crossing the epithelial barrier of the intestine, the bacteria are phagocytosed by macrophages, which are the target cell for this microorganism. Macrophages internalize the bacteria by binding to different receptors, including the complement receptor 3, and phagosomes containing the organisms are formed. Macrophages can destroy M. a. paratuberculosis, but not by way of oxidative compounds. The bacteria manipulate macrophages in order to survive, inhibiting the maturation and acidification of the phagosomes, and modulating macrophage cytokine production and antigen-presentation.

Animals↗
PubMed2001

Evidence for an innate immune response in the immature human intestine: toll-like receptors on fetal enterocytes.

The intestinal epithelium is an active participant in the mucosal immune response against luminal pathogens. Microorganisms and their cell wall products, i.e. lipopolysaccharide (LPS), can stimulate the enterocyte to produce an innate immune response with the increased production of IL-8 via an activation of the transcription factor NFkappaB. The innate response mechanism, however, has not been understood until the recent description of a family of human toll-like receptors (hTLR) on immune cells that interact with LPS and modulate the IL-8 response via an intracellular signal transduction pathway similar to that of the IL-1 receptor family. Accordingly, in this study we have sought to determine the constitutive and regulated expression of hTLR on a nonmalignant human fetal primary small intestinal cell line (H4 cells) and on small intestinal samples of ileum from human fetuses (age 18-21 wk). Specimens were examined by reverse-transcription PCR, Western blot analysis, and immunofluorescence for hTLR2 and hTLR4 mRNA and protein and to determine whether their expression was regulated by LPS or by an endogenous inflammatory stimulus, IL-1beta. hTLR2 and hTLR4 were expressed constitutively on H4 cells and on human fetal small intestinal enterocytes, predominantly on the basolateral surface of crypt enterocytes. Inflammatory stimuli appeared to regulate hTLR transcription (IL-1beta increased both hTLR2 and hTLR4 whereas LPS decreased hTLR4) and possibly translation (qualitative observations). The presence of hTLR on human fetal enterocyte suggests a mechanism for the innate immune response to pathogens and could provide the basis for further study of the accentuated inflammatory response in age-dependent gastrointestinal diseases such as necrotizing enterocolitis.

Base Sequence↗
PubMed2001

Molecular analysis of commensal host-microbial relationships in the intestine.

Human beings contain complex societies of indigenous microbes, yet little is known about how resident bacteria shape our physiology. We colonized germ-free mice with Bacteroides thetaiotaomicron, a prominent component of the normal mouse and human intestinal microflora. Global intestinal transcriptional responses to colonization were observed with DNA microarrays, and the cellular origins of selected responses were established by laser-capture microdissection. The results reveal that this commensal bacterium modulates expression of genes involved in several important intestinal functions, including nutrient absorption, mucosal barrier fortification, xenobiotic metabolism, angiogenesis, and postnatal intestinal maturation. These findings provide perspectives about the essential nature of the interactions between resident microorganisms and their hosts.

Animals↗
PubMed1989

[Micro-ecological aspects of studies on the effect of antibacterial drugs on intestinal microflora].

Possible characterization of intestinal microflora as an integral system after exposure to antibacterial drugs was studied. Microflora of the contents and mucosa of the jejunum and large intestine in control rats and in rats exposed to metronidazole was studied and numerical indicators characterizing ratios of dominating and accompanying microbial groups in the intestine biotope++ were developed. With this purpose the proportion of the microbial groups in the total quantity of the microbes of a microbiocenosis was determined by the data on microflora quantitative composition. On the basis of detected wide species variety of microorganisms potentially dominating by their biotope numerical limits of the norm were determined only for the microbial groups of the accompanying microflora. The total proportion of the accompanying microbial populations under the normal conditions and the detected measure of deviation (reverse, partial) from the ratio of the dominating and accompanying microorganisms peculiar of the given biotope++ in separate subjects promoted estimation of microbiocenoses of definite biotope of the intestine as a whole.

Animals↗
PubMed2002

Homeostatic regulation of intestinal villous epithelia by B lymphocytes.

The epithelial cell of the small intestine is one of the most rapidly regenerating cells in the body. However, the cellular mechanism and biological significance underlying this rapid regeneration remain elusive. In this study we examined the intestinal epithelia of mutant mice that lack B and/or T cells and those of normal littermates. The absence of B cells in Ig mu-chain mutant mice or B and T cells in recombination-activating gene (RAG)-2(-/-) as well as SCID mutant mice was associated with a marked acceleration of epithelial cell turnover and an up-regulation of the expression of MHC class II molecules. No such effects were observed in T cell-deficient TCR-delta and -beta double-mutant mice. As far as the goblet cells of villous epithelium are concerned, absolute numbers of them remained the same among these mutant mice that have no B and/or T cells. Alymphoplasia (aly/aly) mutant mice that lacked Peyer's patches and Ig-producing cells in the lamina propria, but harbored a large number of intestinal mucosal T cells, also displayed a significant acceleration of epithelial cell turnover and, to some extent, up-regulated expression of MHC class II molecules. Notably, the accelerated epithelial cell turnover was not observed and returned to normalcy in the Ig mu-chain mutant mice that had been given antibiotic-containing water. These findings indicate that B cells down-regulate the generation and differentiation of intestinal epithelial cells in the normal wild-type condition and suggest that enteric microorganisms are implicated in the accelerated generation of epithelial cells in mice that have no B cells.

Ampicillin↗
PubMed1986

Gastric acidity: an important factor regulating the composition of the bacterial flora in the small intestine.

The role of gastric acidity in regulating the bacterium composition in the small intestine was studied. Gastric acidity was determined with the Kay test. Intestinal juice obtained by a probe was examined for the presence and number of microorganisms. Parallel with the increase in gastric acidity, the number of bacteria in the jejunal juice generally decreased. Their composition also varied: in anacid patients E. coli predominated whereas in those with free hydrochloric acid, Streptococcus alpha haemolyticus and anaerobic Peptostreptococcus formed the bulk of the microflora. These data underline the importance of the role of acidity in the development of bacterial contamination in the jejunum.

Bacteria↗
PubMed2001

Food processing: probiotic microorganisms for beneficial foods.

Human studies have demonstrated that selected probiotic strains can influence the composition of the intestinal microflora and modulate the host immune system. Considerable promise was also demonstrated for the application of probiotics in human disease. However, the extension of probiotic applications demands increasing scientific attention to their functionality and the identification of molecular structures.

Anti-Bacterial Agents↗
PubMed1996

Diversity of Nitrogen Fixation Genes in the Symbiotic Intestinal Microflora of the Termite Reticulitermes speratus.

The diversity of nitrogen-fixing organisms in the symbiotic intestinal microflora of a lower termite, Reticulitermes speratus, was investigated without culturing the resident microorganisms. Fragments of the nifH gene, which encodes the dinitrogenase reductase, were directly amplified from the DNA of the mixed microbial population in the termite gut and were clonally isolated. The phylogenetic analysis of the nifH product amino acid sequences showed that there was a remarkable diversity of nitrogenase genes in the termite gut. A large number of the termite nifH sequences were most closely related to those of a firmicute, Clostridium pasteurianum, with a few being most closely related to either the (gamma) subclass of the proteobacteria or a sequence of Desulfovibrio gigas. Some of the others were distantly related to those of the bacteria and were seemingly derived from the domain Archaea. The phylogenetic positions of these nifH sequences corresponded to those of genera found during a previous determination of rRNA-based phylogeny of the termite intestinal microbial community, of which a majority consisted of new, yet-uncultivated species. The results revealed that we have little knowledge of the organisms responsible for nitrogen fixation in termites.

Journal Article↗
PubMed1991

Striking structural and functional similarities suggest that intestinal sucrase-isomaltase, human lysosomal alpha-glucosidase and Schwanniomyces occidentalis glucoamylase are derived from a common ancestral gene.

Sequence comparison of the primary structure of the yeast Schwanniomyces occidentalis glucoamylase (GAM) with GAMs in different microorganisms did not reveal significant similarities. By contrast, striking similarities were, surprisingly, found with 3 mammalian secretory and integral membrane proteins: the 2 subunits of intestinal brush border sucrase-isomaltase and human lysosomal alpha-glucosidase. The similarities among these proteins are found as clusters of up to 8 amino acids and distributed all over the protein sequences. The major sequence differences are found in the N-terminal regions accounting, probably, for the different cellular locations of these proteins. The high level of similarities between sucrase, isomaltase, Sch. occidentalis GAM and human lysosomal alpha-glucosidase suggest that these proteins are derived from the same ancestral gene. To our knowledge, this is the first report that describes similarities between a yeast secretory protein and mammalian secretory and integral membrane proteins.

Amino Acid Sequence↗
PubMed1983

Mechanisms by which indigenous microorganisms colonize gastrointestinal epithelial surfaces.

Indigenous microorganisms are known to associate with epithelial surfaces in the gastrointestinal tracts of birds and mammals of many species. In general, the mechanisms by which microorganisms associate with the epithelia are poorly understood. In some cases, in associating with epithelial surfaces, the microbial species involved undoubtedly colonize (i. e., multiply on) them. Some examples of such microorganisms are strains of certain Lactobacillus, and Candida (Torulopsis) species that associate with gastric surfaces, and strains of segmented, filamentous and of oxygen-intolerant anaerobic bacteria of numerous species that associate with intestinal surfaces in mice and rats. Several properties of the microbial cells involved may be important for them to be able to colonize epithelial habitats. Some such properties are a capacity for the cells to adhere to structures on the epithelium, or to be motile and able to move into the mucous gel present on most gastrointestinal surfaces. In addition, microorganisms that can colonize surface microhabitats on gastric or intestinal epithelia must be able to thrive in the environments and nutritional circumstances found in such habitats. In this respect, a capacity to multiply well in environments containing high concentrations of hydrogen ion is important for microbial cells to be able to colonize gastric surfaces, while a capacity enzymatically to digest mucinous glycoproteins and use the degradation products as carbon, energy and nitrogen sources may be important for microorganisms to be able to colonize most gastric or epithelial surfaces. These and related issues are examined in this paper.

Animals↗
PubMed1991

Comparative effects of clarithromycin and erythromycin on the normal intestinal microflora.

10 healthy volunteers received 250 mg of clarithromycin orally q 12 h for 7 days and 10 other volunteers 1000 mg of erythromycin ethylsuccinate orally q 12 h for 7 days. Stool specimens were collected before, during and after antibiotic administration. In the clarithromycin group, the numbers of streptococci and enterobacteria decreased among aerobic microorganisms while in the erythromycin group streptococci, enterococci and enterobacteria decreased and staphylococci increased during antibiotic administration. The anaerobic intestinal microflora was also affected. The alterations were more pronounced in the volunteers receiving erythromycin than in those having clarithromycin.

Administration, Oral↗
PubMed1980

Ecological investigation on intestinal bacterial flora of patients nursed in protected environmental units.

The present results of investigations performed on fresh fecal samples from a healthy adult and subjects with acute leukemia cultured bacteriologically using both aerobic and anaerobic techniques have led to the following conclusions. 1) In studies on the intestinal bacterial flora of the subjects examined, obligate anaerobic bacteria rather than facultative anaerobes accounted for more than 99% of the microorganisms. 2) Although some qualitative differences seem to exist between fecal bacterial flora components of the normal individual and leukemia patients examined, further investigations considering various factors controlling and influencing the composition of intestinal bacterial flora are needed to evaluate the results obtained. 3) The results obtained herein indicate that changes in intestinal bacterial flora induced by non-absorbable antibiotics are associated with the host defense mechanisms. 4) The relative predominance of aerobic versus anaerobic bacterial flora in the intestine may reflect the degree of severity of clinical manifestation in leukemia patients. In the data obtained from the present investigations, the predominating fecal anaerobic bacteria may serve as a base line for the evaluation and interpretation of the host defense system by patterns of the components of bowel flora brought about by internal or external environmental changes.

Acute Disease↗