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PubMed1986

Scanning electron microscopy of isolated epithelium of the murine gastrointestinal tract: morphology of the basal surface and evidence for paracrinelike cells.

By using the method of Bjerknes and Cheng, isolated murine gastrointestinal epithelial sheets were prepared for scanning electron microscopy. Examination of isolated epithelium from fundic stomach revealed numerous branched gastric glands. Parietal cells were easily detected bulging from the basal surface of the glandular epithelium. The basal surface membrane of parietal cells appeared smooth, with only sparse microvilluslike projections, whereas adjacent glandular cells had numerous 1- to 2-micron fingerlike projections which interdigitated laterally with similar processes from adjacent cells. Occasionally, paracrinelike cells having long cytoplasmic processes ranging from 10 to 20 micron in length were observed on the basal epithelial surface of the stomach and the colon, but not the small intestine. In isolated intestinal epithelia, the basal surface of crypt epithelial cells showed extensive cytoplasmic interdigitations, but no distinct morphology permitting recognition of individual cell types. Various stages of intestinal crypt bifurcation were seen. Craterlike spaces in the basal surface of crypt epithelium, presumably due to migrating leukocytes, were also numerous. Examination of the luminal surface of the isolated intestinal epithelium revealed that intimate associations between epithelium and mucosal-associated microorganisms were maintained, thus suggesting that minimal alterations in surface morphology were incurred by epithelial isolation. These observations on epithelial structure suggest that isolated gastrointestinal epithelia may be well suited for physiological studies of epithelial function and interactions with the microbial flora.

Animals↗
PubMed2006

Involvement of dendritic cells in the pathogenesis of inflammatory bowel disease.

In conclusion, during inflammation, DCs are likely activated by inflammatory signals and induced to migrate to T cell zones of organized lymphoid tissues where the cells induce T cell responses. In addition to their established role in T cell priming and the induction of tolerance, DCs may act to enhance (or possibly suppress) T cell responses at sites of mucosal inflammation. Determining the importance of DCs in this regard, as well as establishing a potential role for DCs in continuous activation of naive or central memory cells in lymph nodes draining inflammatory sites, will elucidate the role of DCs as a potential therapeutic target for chronic inflammatory diseases, like IBD. Resident intestinal macrophages are noninflammatory and do not efficiently present antigens to intestinal T cells, yet are avidly phagocytic and able to kill internalized organisms. During intestinal inflammation, monocytes are recruited from the blood, become inflammatory macrophages in the inflamed tissue, and are major contributors to tissue destruction and perpetuation of inflammation via their production of chemokines and pro-inflammatory cytokines. Macrophages may also contribute directly to DC activation and maturation, which would drive DCs to present antigens from the bacterial flora to T cells locally within tissue or to more efficiently traffic to T cell zones of lymphoid tissue. Thus, DCs and macrophages have evolved functional niches that promote cooperation in the prevention of untoward intestinal inflammation in the steady state and in the eradication of invasive microorganisms during infection. The balance between suppressing inflammation and promoting host defense is altered in humans with IBD allowing a persistent inflammatory response to commensal bacteria. Based on studies from animal models, the pathogenesis of IBD likely involves either the lack of appropriate regulation from T cells, or an over-production of effector T cells. The end result of these potential mechanisms is the abnormal induction and/or survival of effector T cells and the production of factors such as cytokines by inflammatory macrophages and neutrophils that result in tissue destruction. The destructive process likely involves normally tolerizing DCs, which in the microenvironment of the inflamed mucosa activate T cell responses to normal flora in both draining lymphoid tissues and at sites of inflammation, with macrophages and neutrophils contributing the bulk of inflammatory and destructive cytokines.

Animals↗
PubMed1989

Urinary excretion of 2,3-butanediol and acetoin by babies on a special care unit.

2,3-Butanediol was detected by capillary gas chromatography in 45 urine samples from 20 babies on a special care unit, 17 of whom were premature. The meso form of the diol predominated and in 21 samples was the only diastereoisomer present. Acetoin was found in 20 of the samples. It was never detected in the absence of 2,3-butanediol. 2,3-Butanediol was not detectable in more than trace amounts in urine from 66 other babies on the unit. The most likely origin of these compounds was from bacterial fermentation of pyruvate in the gut. Their presence may be explained by abnormal gut colonisation with acetoin-producing microorganisms, an abundant supply of nutrient lactose in the colon and increased intestinal permeability. It is further evidence of the magnitude of intestinal carbohydrate fermentation in preterm babies. 2,3-Butanediol could prove a useful biochemical marker for abnormal colonisation of neonates on special care units.

Acetoin↗
PubMed2005

Identification and molecular characterization of a peritrophin-like protein from fleshy prawn (Fenneropenaeus chinensis).

Peritrophin, one of the components of the peritrophic matrix, was first isolated from the intestine of insects. It is thought to protect insects from invasion of microorganisms and to stimulate digestion of food. Peritrophin-like proteins have also been found in crustaceans, as a component of the egg layer. In this study, one fragment of the peritrophin-like gene was obtained from fleshy prawn (Chinese shrimp) (Fenneropenaeus chinensis) by panning the T7 phage display library constructed with the shrimp hemocyte cDNA. The total sequence of the peritrophin cDNA was cloned by modified SMART cDNA and LD-PCR methods. The full cDNA is 1048bp and the deduced protein is composed of 274 amino acids, including 21 amino acid signal peptide, and four peritrophin A domains and the latter three forming three chitin-binding domains. Similarity analysis results showed that the peritrophin-like protein from F. chinensis has significant similarities with peritrophin-like and cortical rod proteins from other shrimp. It was inducing expression in hemocytes, heart, stomach, gut, and gills of the infected shrimp, and constitutive expression in the ovaries. No expression signal was detected in the hepatopancreas of either infected or noninfected shrimp. The recombinant peritrophin-like protein has the activity of binding Gram-negative bacteria and strong binding activity to chitin. Therefore, the bacteria and chitin binding activities of the peritrophin-like protein suggest that it may plays a role in immune defense and other physiological resposes.

Amino Acid Sequence↗
PubMed2000

Colonic food: pre- and probiotics.

The colonic mucosa is unable to nourish itself from the blood. Instead, its nutritive demand must be met from the lumen, where different nutrients, short-chain fatty acids, amino acids, polyamines, growth factors, vitamins, and antioxidants are produced by a nonpathogenic (commensal, so-called "protective" probiotic) flora. The substrates for the production of nutrients are usually referred to as prebiotics, which consist mainly of ingested fibers and complex proteins (colonic food), but may also include necrotic mucosal cells, mucus, gastrointestinal (GI) secretions, and bacteria (as well as yeasts broken down by the bacteria). A characteristic common to all foods destined for the colon--colonic foods-is that no enzymes in the small intestine are capable of breaking them down. It is recommended that a minimum of 10% of ingested calories and about 20% of the food volume should be colonic food. The probiotic flora is today often found deficient, especially in industrialized nations. Studies have shown that Lactobacillus plantarum can preserve key nutrients, vitamins, and antioxidants; eliminate toxic components from food; protect food from decay; and eradicate pathogens such as Enterobacteriaceae, S. aureus, and enterococci from fermented food. In addition, it has demonstrated effectiveness over other bacteria in the metabolism of semiresistant oligofructans. L. plantarum-fermented oat given to healthy volunteers significantly reduces the gut content of potentially pathogenic microorganisms (PPMs).

Animals↗
PubMed1989

Influence of diet and monensin on development of anaerobic fungi in the rumen, duodenum, cecum, and feces of cows.

Three cows with fistulated rumens, duodenums, and ceca were fed five different diets: lucerne hay, lucerne hay plus whey (40:60), lucerne hay plus beets (50:50), corn silage plus monensin (40 ppm [40 g/kg] of dry matter intake), and lucerne hay plus monensin (80 ppm of dry matter intake). The fungal population was observed in the rumen, duodenum, cecum, and rectum and varied with diet; it was most abundant with lucerne hay alone and with corn silage plus monensin. The proportion of particles colonized by fungi in the duodenum, the cecum, and feces was measured by microscopic observation and varied from 5 to 50%, depending on the diet. The further sporangia attached to the plant particles were from the rumen, the more likely they were to be devoid of spores. Results confirmed the influence of diet on the development of the ruminal fungal population and showed that monensin does not eliminate these microorganisms. They also confirmed the presence of anaerobic fungi in the ruminant intestine. It is likely that anaerobic fungi leave the rumen attached to plant particles. However, large colonies of nonrhizoidal-type fungi were observed in cecum samples and in feces; at these sites, environmental conditions are perhaps more favorable for this type of fungus than they are in the rumen.

Anaerobiosis↗
PubMed1999

Phylogeny of the defined murine microbiota: altered Schaedler flora.

The "altered Schaedler flora" (ASF) was developed for colonizing germfree rodents with a standardized microbiota. The purpose of this study was to identify each of the eight ASF strains by 16S rRNA sequence analysis. Three strains were previously identified as Lactobacillus acidophilus (strain ASF 360), Lactobacillus salivarius (strain ASF 361), and Bacteroides distasonis (strain ASF 519) based on phenotypic criteria. 16S rRNA analysis indicated that each of the strains differed from its presumptive identity. The 16S rRNA sequence of strain ASF 361 is essentially identical to the 16S rRNA sequences of the type strains of Lactobacillus murinis and Lactobacillus animalis (both isolated from mice), and all of these strains probably belong to a single species. Strain ASF 360 is a novel lactobacillus that clusters with L. acidophilus and Lactobacillus lactis. Strain ASF 519 falls into an unnamed genus containing [Bacteroides] distasonis, [Bacteroides] merdae, [Bacteroides] forsythus, and CDC group DF-3. This unnamed genus is in the Cytophaga-Flavobacterium-Bacteroides phylum and is most closely related to the genus Porphyromonas. The spiral-shaped strain, strain ASF 457, is in the Flexistipes phylum and exhibits sequence identity with rodent isolates of Robertson. The remaining four ASF strains, which are extremely oxygen-sensitive fusiform bacteria, group phylogenetically with the low-G+C-content gram-positive bacteria (Firmicutes, Bacillus-Clostridium group). ASF 356, ASF 492, and ASF 502 fall into Clostridium cluster XIV of Collins et al. Morphologically, ASF 492 resembles members of this cluster, Roseburia cecicola, and Eubacterium plexicaudatum. The 16S rRNA sequence of ASF 492 is identical to that of E. plexicaudatum. Since the type strain and other viable original isolates of E. plexicaudatum have been lost, strain ASF 492 is a candidate for a neotype strain. Strain ASF 500 branches deeply in the low-G+C-content gram-positive phylogenetic tree but is not closely related to any organisms whose 16S rRNA sequences are currently in the GenBank database. The 16S rRNA sequence information determined in the present study should allow rapid identification of ASF strains and should permit detailed analysis of the interactions of ASF organisms during development of intestinal disease in mice that are coinfected with a variety of pathogenic microorganisms.

Animals↗
PubMed1999

Bacterial invasion is not required for activation of NF-kappaB in enterocytes.

Pathogenic enteric microorganisms induce the NF-kappaB-dependent expression of proinflammatory genes in intestinal epithelial cells. The purpose of the present study was to clarify the contribution of microbial invasion to the degradation of the regulatory protein Ikappa Balpha and the subsequent activation of NF-kappaB in cultured intestinal epithelial cells. Caco-2BBe cells were incubated with Salmonella dublin, Salmonella typhimurium, or a weakly invasive strain of E. coli. S. dublin and S. typhimurium (10(7) organisms/ml) induced equivalent concentration-dependent gel mobility shifts of an NF-kappaB consensus sequence that was preceded by Ikappa Balpha degradation. E. coli (10(7) organisms/ml) did not induce Ikappa Balpha degradation or NF-kappaB translocation. Pretreatment with cytochalasin D blocked invasion of all three strains but had no effect on Ikappa Balpha degradation or NF-kappaB activation. S. dublin and S. typhimurium adhered to Caco-2BBe cells 3- to 10-fold more than E. coli. NF-kappaB activation was prevented by physical separation of S. dublin from Caco-2BBe cells by a 0. 4-micrometers-pore-size filter. Our results imply that bacterial adhesion, rather than invasion or release of a secreted factor, is sufficient to induce IkappaBalpha degradation and NF-kappaB activation in intestinal epithelial cells. Our data suggest that strategies to reduce enteric inflammation should be directed to the reduction of bacterial enterocyte adhesion.

Caco-2 Cells↗
PubMed1999

Mortality in farmed mink: systematic collection versus arbitrary submissions for diagnostic investigation.

The distribution of diagnoses of mortality in mink submitted to the Danish Veterinary Laboratory (DVL) for diagnostic investigation in the calendar year 1997 was compared with the diagnoses of mortality in all dead mink collected at 4 selected farms (project farms) during the same period. A total of 1,015 submitted mink and 1,149 mink from the 4 project farms were subjected to post mortem investigation. The average size (breeding stock) of the project farms was larger than Danish farms on average. However, the distribution of colour types of the mink was comparable. The seasonal distribution of the material from project farms and that of the submissions were approximately the same. Differences in the distribution of diagnoses as well as recovered microorganisms were found, however, mainly related to the proportion of gastro-intestinal disorders and E. coli respectively. These proportions were negatively correlated. Overall the results showed that extrapolating diagnostic results of laboratory submissions to the population of farmed mink may be problematic, and more reliable methods for disease surveillance must be considered.

Animals↗
PubMed2006

[The bacterial QS-systems and prospects of creation of new metabolic probiotic preparations].

Biological functions of exometabolits of various bacterial species were analyzed from Quorum Sensing position, which showed that the functional activity of microbiocenosis is in many respects determined by the system of metabolic regulation. Possibility of changing the composition of complex microbial communities with low-molecular compounds, products of bacterial cell vital activity, is grounded from theoretical point of view. The authors adduce data on the effects of a synthetic composition on the basis of E. coli metabolites, an ingredient of colibacterin, a probiotic preparation. The preparation demonstrated a high stimulating activity towards a range of microorganisms of normal microflora, and an ability to improve the condition of intestinal epitelial cells. The results may substantiate application of metabolic probiotics for correction of intestinal microflora in man.

Bacterial Physiological Phenomena↗
PubMedDate not supplied

[Possible entry of fragments of a bacterial genome into the trophozoite nucleus of the dysentery amoeba].

The use of Fölgen-like electron microscopy reaction has revealed particles in the cytoplasm and nucleus of the dysentery amoeba trophozoites which in their size and resistance to acidic hydrolysis and in their affinity for uranilacetate are similar to tightly packed elements of the bacterial genome. On this basis a conclusion was drawn that some fragments of genomes of phagocytic bacteria can be preserved in the amoebal cell. The community of microorganisms consisting of trophozoites of the dysentery amoeba and bacteria of the intestinal flora is supposed to be a suitable model for studying the possibility of penetration of transgenetic elements from procaryote to eucaryote.

Animals↗
PubMed1988

Isolation of Clostridium spiroforme from rabbits.

The isolation of Clostridium spiroforme from intestinal contents of rabbits was achieved by sampling the supernatant-pellet interphase of centrifuged specimens processed for routine toxin analysis. High-speed centrifugation at 20,000x for 15 minutes provided a rapid and effective means of separating this anaerobic pathogen from the majority of both indigenous and non-indigenous intestinal microbial flora. The unusual helically-coiled, semicircular shape of the microorganism is considered, at least in part, responsible for this phenomenon.

Animals↗
PubMed1994

[Diarrhea due to rare forms of colitis: microscopic (lymphocytic, collagenous) colitis and spirochetosis].

Lymphocytic and collagenous colitis, uncommon entities that are identifiable by histopathologic examination only, and intestinal spirochetosis may cause chronic diarrhea. Data on incidence, histopathology, and diseases associated with these infrequent forms of colitis are reviewed. Etiology and pathogenesis of lymphocytic and collagenous colitis are still unknown, but immuno-inflammatory factors may be involved in both forms as well as, in collagenous colitis, primary disorders of collagen metabolism or drug-induced toxic effects. The significance of intestinal colonization by spirochetes is disputed; however, recent results indicate that these microorganisms are capable of inducing disease.

Adult↗
PubMed1993

[Selective gut decontamination in ventilated intensive therapy patients].

Treatment of long-term artificially ventilated patients is often complicated by nosocomial infections. The infection that occurs with the highest frequency during intensive care treatment is pneumonia (22-63%). Ninety per cent of nosocomial infections of intensive care patients are endogenous infections caused by mainly gram-negative aerobic microorganisms that have colonized in the gastrointestinal tract. Selective decontamination of the intestine provides a method that prevents nosocomial infections. In a prospective study 13 patients whose oropharynx and gastrointestinal tract had been decontaminated (SDD) were compared to 17 patients in a control group. In a third group twelve patients were decontaminated in the gastrointestinal tract (SGD) only, and in a fourth group 16 patients were decontaminated in the oropharynx (SMD) only. Trachea, oropharynx and faeces of the patients belonging to the control group (KG) were colonized to almost 100% with gram-negative bacteria. Only 10% of the patients of the SDD and SMD groups showed gram-negative bacteria located in the trachea and oropharynx after one week of decontamination. No gram-negative aerobic bacteria were present after seven days in the faeces of the patients of the SDD and SGD groups. There was no difference with regard to the trachea and oropharynx between the control group and the SGD group. The gram-negative aerobic intestinal flora was not affected by the selective mouth decontamination. The average rate of pneumonia occurrence within the 15-day observation period was 28.2% for the control group, 14% for the SGD group, and 9.6% for the SDD group, and 4.1% for the SMD group. Decontamination of the oropharynx of patients is essential in order to successfully prevent pneumonia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[Formation of intestinal microflora in children during the first year of their life].

In 525 young children the state of intestinal microbiocenosis was studied every month of the first year their life. The study revealed that the process of the microflora formation lasted throughout the first year of their life and was characterized by dysbiotic disturbances. During this period the aggravation of dysbiotic changes in the intestine of these children on months 3, 6-7 and 11-12 was of particular importance. The formation of stable dysbacteriosis led to a decrease in the immunological status of the child, which was manifested by the increased content of such microorganisms as hemolytic cocci, Proteus and a decrease in the quantitative level of bifidobacteria in the total intestinal microbiocenosis by the end of the first year of child's life.

Bacteria↗
PubMed1999

Plasticity of the gastrointestinal epithelium: the M cell paradigm and opportunism of pathogenic microorganisms.

The maintenance during adult life of a large spectrum of pluripotency by stem cells originating from the endoderm seems to be the grounds for the striking plasticity of the digestive epithelium, which is able to drastically modify its differentiation pattern depending on the microenvironment. As a paradigm, Peyer's patch M cell development appears to be induced by crosstalk between lymphoid cells and/or microorganisms. Examples of pathological transdifferentiation of epithelia, also described as 'metaplasia' and affecting various organs, support the concept of intestinal plasticity. Though, the molecular processes involved in epithelial transdifferentiation have not been identified, histological analyses of these metaplastic tissues and experimental induction of transdifferentiation of normal epithelia provide lines of evidence suggesting that a modification of the local environment, such as occurs during contact of the epithelium with lymphoid cells or microorganisms, plays a key role in this process.

Epithelial Cells↗