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PubMed1985

Experimental elimination of various intestinal segments by means of devascularization (devitalization).

Segments of the small and large intestine, of varying lengths (10-180 cm), were devascularized by simultaneously ligating the mesenteric arteries and veins. When the circulation had been cut off, the ends of the devascularized segment were both ligated, continuity of intestinal passage was renewed by forming an anastomosis and the isolated segment was left in situ, together with its contents. Contrary to accepted views, no changes leading to death (necrosis and peritonitis) occurred, but the devascularized tissue was progressively destroyed and reconstructed until, after four weeks, all that was left was a minute fibrous residue. None of 41 pigs died as a result of devascularization, including those in which large doses of pathogenic microorganisms were injected into the isolated segment. The possibility of employing this technique in the surgical treatment of inoperable tumours is discussed.

Animals↗
PubMedDate not supplied

[Principal characteristics and diagnosis of the pathogenic groups of Escherichia coli].

Escherichia coli colonizes the human intestinal tract within hours of birth and is considered a non-pathogenic member of the normal intestinal flora. However, there are six pathogenic groups that may produce diarrhea: enterotoxigenic (ETEC), enterohemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC), enteroaggregative (EAEC) and diffusely adherent (DAEC) groups. E. coli can be isolated and classified using traditional methods, by identifying its biochemical or serum characteristics. The pathogenic mechanisms may be studied in cell cultures and animal model assays, as well as more up to date molecular biology methods for study and diagnosis. The latter have proven that genes are involved in pathogenesis. The objective of the present work is to draw attention to the importance of E. coli as a pathogenic organism. This microorganism is an etiologic agent of sporadic cases of diarrhea, hemorrhagic colitis, dysentery, and hemolytic uremic syndromes and outbreaks. Diarrheic E. coli manifestations occur mainly among infants, and deep knowledge and understanding of this microorganism are crucial to better epidemiologic surveillance.

Adult↗
PubMed2005

In vitro availability of lomefloxacin hydrochloride in presence of essential and trace elements.

Lomefloxacin hydrochloride is a third generation fluoroquinolone antibacterial agent having a broad spectrum of action against a wide range of gram-positive and gram-negative organisms. The in vitro availability studies of lomefloxacin were carried out in presence of essential and trace elements such as magnesium, calcium, chromium, ferric, ferrous, cobalt, nickel, copper, zinc and cadmium in simulated gastric juice, simulated intestinal juice and blood pH at 37 degrees C using B.P 2003 dissolution test apparatus. It was observed that availability of lomefloxacin was depressed in presence of nickel and zinc in simulated gastric juice and in presence of Fe2+ in simulated intestinal juice, while many metals like magnesium, chromium, iron (both Fe2+ and Fe3+), cobalt, nickel, copper and cadmium depressed the availability of lomefloxacin at blood pH. Furthermore, the availability of lomefloxacin alone in simulated intestinal juice and at blood pH was reduced as compared to simulated gastric juice. The antibacterial activities of lomefloxacin in presence of these metal ions were observed and compared to control against six different microorganisms i.e., Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Bacillus fragilis and Streptococcus pneumonia by disc diffusion method to measure the inhibitory zone and MIC were determined by tube dilution method.

Anti-Bacterial Agents↗
PubMed1996

[Gastrointestinal mucus].

Gastrointestinal mucus (GIMu) is a viscoelastic gel, which covers the surface of the entire digestive tract. The main component of GIMu is mucin, which is a high molecular weight glycoprotein. Mucin is composed of a central peptide core with polysaccharide chains arranged radially from the core ("bottle brushappearance"). The carbohydrates are very hydrophilic and, therefore, able to bind large amounts of water, which partly accounts for the gel-forming properties of GIMu. GIMu has an important function as a barrier against large particles, H+ ions and pepsin, carcinogens, certain macromolecules and microorganisms. GIMu seems to be involved in the pathogenesis of gastroduodenal ulceration, inflammatory bowel disease, gastrointestinal malignancies, gallbladder stones and infectious diarrhoeal diseases. GIMu is also an important factor in maintaining the normal microbial intestinal homeostasis. In the future, a more detailed knowledge about the molecular structure and function of GIMu may lead to new diagnostic and therapeutic strategies for gastrointestinal diseases.

Gastric Mucosa↗
PubMed2002

[The colon as an organ: habitat of bacterial flora].

The intestinal flora constitutes a complex ecosystem comprising several hundred species of micro-organism, most of them in the genus bacteria. This ecosystem includes some micro-organism considered to be pathogenes for their capacity to invade the host, but they also contain numerous species capable of promoting beneficial effects on health. Bacterial flora begins to be acquired inmmediately after birth. By the age of two years, the flora etablished is practically definitive. There are transiet modifications derived from the use of antibiotics or in connection with changes in diet, but these are normally reversible so that every individual tends to have a relatively stable flora. The composition of bacterial flora varies from one individual to another but it is metabolic functions show less diversity. The flora in the human colon is like an organ with intense metabolic activity due to the action of bacterial enzymes on the substrates present in the intestine. Many authors have considered it more relevant to identify the enzymatic activity of the bacterial flora than the variety of species contained. The main function of the flora are: 1) fermentation of dietary waste and endogenous mucins; 2) energy recovery through the generation of short-chain fatty acids; 3) protection against colonization and invasion by pathogens (barrier effect), and 4) development, stimulation and modulation of the immune system. Special attention has been paid in recent years to the recognition of certain bacterial species that can have such salutary effects on the host. Probiotics are living microorganism that are consumed in order to obtain a beneficial effect regardless of their intrinsic nutritional value. Considerable experimental evidence has been gathered to suggest that probiotics are useful in many health-related spheres. There is good documentation to the effect that the consumption of yoghurt reduces the signs and symptoms of intestinal lactase deficiency. Some probiotics have been shown to be useful in the prevention and treatment of acute diarrhoea due to rotavirus in children and adolescents. The consumption of certain probiotics has also been seen to reinforce certain functions in the human immune system.

Bacterial Physiological Phenomena↗
PubMed1997

Summary of round table conference: gut dysfunction in critical illness.

There is recent evidence that intestinal function is an important determinant in the outcome of critically ill patients. The barrier function is an important characteristic of the gut. Its workings are complex and it consists of epithelial, molecular, and immune components. The pathogenesis of gut dysfunction among critically ill patients is multifactorial, consisting of the quality and quantity of microorganisms, the permeability of the epithelium, and the extent of the vascular perfusion. A practical bedside measure of gut dysfunction is intolerance to enteral feedings. Potential therapies for gut dysfunction include the use of vasoactive drugs to enhance perfusion, selective decontamination to decrease bacteria and endotoxin, and the early and frequent administration of enteral nutrients.

Critical Illness↗
PubMed1991

[Behavior of Clostridium perfringens in the intestine of newborn infants born by cesarean section].

Colonization of the digestive tract by C. perfringens was studied in infants born by cesarean section. Correlations between the level of colonization and the environment, type of feeding, and presence of other anaerobic bacteria were looked for. Colonization by C. perfringens was found as early as the second day of life in one of the maternity wards studied, suggesting presence of the microorganism in the environment. By the 14th day of life, colonization with C. perfringens was demonstrated in all the bottle-fed or breast and bottle-fed infants. In strictly breast-fed infants, findings suggested antagonism between Bifidobacterium and C. perfringens. Bacteroïdes and Clostridium species other than C. perfringens were not found prior to colonization by C. perfringens.

Bifidobacterium↗
PubMed2000

Six intestinal microflora-associated characteristics in sport horses.

The aim of this study was to investigate 6 microflora-associated characteristics (MACs) in faecal samples from horses and to compare the results with baselines previously established in other mammals. A MAC is defined as any anatomical structure, physiological, biochemical or immunological characteristic in a host, which has been acted on by microorganisms. When the active microbes are absent, as in germ-free animals and healthy newborn organisms, the corresponding characteristic is defined as germ-free animal characteristic (GAC). The MACs studied were degradation of mucin, conversion of cholesterol to coprostanol and bilirubin to urobilinogens, inactivation of tryptic activity, degradation of beta-aspartylglycine and excretion of short-chain fatty acids. Five MACs were studied in 19 sport horses and the mucin pattern investigated in 25 other sport horses. Our results show that conversion of cholesterol to coprostanol was present in all horses, irrespective of diet. All horses also demonstrated excretion of urobilinogens; however, the values varied depending on diet. Mucin and beta-aspartylglycine were totally degraded, as occurs similarly in other animal species. Excretion of short-chain fatty acids was lower than values previously found in man, rats and pigs, and the level of faecal tryptic activity was low. Our results show that the MAC/GAC concept is as good in monogastric herbivores as in omnivores for investigations of endogenous and exogenous factors influencing the intestinal ecosystem(s). Therefore, use of the MAC/GAC concept has a potential significance for future studies on functions related to the microflora.

Animals↗
PubMed1994

Detection of large fragments of the human milk mucin MUC-1 in feces of breast-fed infants.

Evidence is growing that high-molecular-weight glycoproteins (mucins) of human milk bind to certain pathogenic microorganisms and thus could interfere with their colonization of the infant gut. This investigation sought to determine whether one of the two principal milk mucins, MUC-1 (also known as PAS-0 and episialin), persists into the feces. Fecal samples from seven breast-fed and seven formula-fed infants, aged from 20 days to 6 months, were analyzed. Glycoproteins in the specimens, solubilized with sodium dodecylsulfate, mercaptoethanol, and heat, were resolved by gel electrophoresis. The gels were blotted on nitrocellulose sheets that were immunostained with monoclonal antibodies specific for epitopes in the tandem repeat region of MUC-1. Mucin fragments of approximately 200,000 MW were detected in specimens from three of the seven breast-fed subjects; only one of them showed evidence of the intact mucin. Four breast-fed and all seven formula-fed babies were negative for the mucin in their stools. While these results provide evidence of a variable degree of breakdown, we speculate that MUC-1 resists degradation in the gut and thus may help bind host-detrimental microorganisms and inhibit their colonizing and infecting actions.

Animals↗
PubMed1997

Paneth cells and innate immunity in the crypt microenvironment.

Paneth cells release granules into the lumen of the crypts of Lieberkuhn in the small intestine where their component proteins participate in mucosal immunity. The granules contain a number of proteins associated with roles in host defense, including lysozyme, secretory phospholipase A2, and alpha-defensins, termed cryptdins. Mouse cryptdins 1-6 and recombinant human Paneth cell alpha-defensin HD-5 are potent antimicrobial agents against certain microorganisms. As defensins, they kill microbes by disruption of the target cell membrane. The peptides are coded by individual, two-exon genes that map to homologous regions of chromosome 8 in mice and humans, and the differential expression of certain mouse cryptdin genes provides markers for studies of crypt ontogeny and epithelial cell differentiation and lineage determination. Neutrophil alpha-defensin peptides exhibit numerous biological activities in addition to antimicrobial function including regulation of cell volume, chemotaxis, mitogenicity, and inhibition of natural killer cell activity. When administered apically, mouse cryptdins 2 and 3 can reversibly stimulate human T-84 intestinal epithelial cells to secrete chloride ion, suggesting that alpha-defensins from Paneth cells also may be multifunctional. Thus, cryptdins and varied Paneth cell secretory products seem to contribute both to innate immunity of the crypt lumen and to defining the apical environment of neighboring cells.

Animals↗
PubMed1996

Paneth cell defensins: endogenous peptide components of intestinal host defense.

Paneth cells are epithelial granulocytes at the base of the crypts of Lieberkühn in the small intestine of many mammalian species. These secretory cells contribute to mucosal barrier function by the apical release of granules containing a variety of antimicrobial products, including peptides termed cryptdins, for crypt defensins. In mice, six Paneth cell defensins have been characterized at the peptide level that have potent antimicrobial activities equivalent to or greater than that of rabbit neutrophil defensin NP-1. Cryptdin peptides that differ only by single amino acid substitutions have been shown to exhibit a high degree of specificity against certain target microorganisms. Cryptdins are coded by separate, two-exon genes that are located on chromosome 8 in both mice and humans. Human Paneth cells contain high levels of two different defensin mRNAs, but in mice at least 19 cryptdin isoforms are predicted from cDNA sequencing data. The mouse cryptdin-4 gene is expressed with positional specificity along the longitudinal intestinal axis, and cryptdin genes are active in the intestinal epithelium prior to Paneth cell differentiation. Accordingly, Paneth cell defensins are early markers of crypt ontogeny and are therefore useful in studies of lineage determination in the intestinal epithelium. Because cryptdins mediate innate immunity in the hostile environment of the intestinal lumen, it should be of interest to define biochemical and biophysical attributes that adapt these peptides to barrier function of mucosal surfaces.

Amino Acid Sequence↗
PubMed1995

Anticarcinogenic, hypocholesterolemic, and antagonistic activities of Lactobacillus acidophilus.

Lactobacillus acidophilus is considered to possess health-promoting attributes. These include anticarcinogenic and hypocholesterolemic properties and antagonistic action against intestinal and food-born pathogens. L. acidophilus can also survive the hostile environment and establish in the complex ecosystem of the gastrointestinal tract. Therefore, the beneficial effects of ingesting L. acidophilus accrue over a longer period than those organisms that cannot colonize the gut. However, the exact mechanisms of these attributes are not known. Presumably, the anticarcinogenic activity may be attributed to production of compounds and/or conditions that inhibit the proliferation of tumor cells, suppression of microorganisms that convert procarcinogens to carcinogens, and degradation of carcinogens formed. They hypocholesterolemic effect is probably exerted by inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, which is a rate-limiting enzyme in endogenous cholesterol biosynthesis in the body and by promoting the excretion of dietary cholesterol in feces as a result of coprecipitation in the presence of deconjugated bile acids in the intestine and/or adsorption by the organisms. The antagonistic effect against pathogens and other organisms is possibly mediated by competition for nutrients and adhesion sites, formation of metabolites such as organic acids, hydrogen peroxide, and production of antibiotic-like compounds and bacteriocins.

Antibiosis↗
PubMed1990

Recent advances in rumen microbial ecology and metabolism: potential impact on nutrient output.

Feedstuffs consumed by ruminants are all initially exposed to fermentative activity in the rumen prior to gastric and intestinal digestion. The extent and type of transformation of feedstuffs thus determines the productive performance of the host. Research on rumen microbial ecology and metabolism is essentially a study of the interactions between the host, microorganisms present, substrates available, and end products of digestion. Furthermore, the interactions of the normal microbial flora with the host can be manipulated to improve the efficiency of nutrient utilization in ruminant animals. Three important areas of ruminal fermentation will be reviewed, N metabolism, fiber degradation, and biotransformation of toxic compounds. The extent of protein degradation and the rate of uptake of resultant peptides and ammonia are extremely important factors in determining the efficiency of N utilization by rumen bacteria and, therefore, the relative amounts of microbial or bypass protein available to the host. Strategies aimed at identifying and characterizing rate-limiting enzymes of cellulolytic bacteria are essential in elucidating mechanisms involved in ruminal fiber degradation. Results obtained with ruminococci will be described. The detoxification of phytotoxins by passage through the gastrointestinal tract of ruminants is a process deserving special attention and several examples will be presented. Opportunities for manipulation of rumen fermentation are good. However, successful manipulation and full exploitation depend on a through understanding of the mechanisms involved.

Animal Feed↗
PubMed1991

[Negative effects of anti-nutritional factors in animal feed on nitrogen burden of the environment and possibilities of its reduction. Nutritional physiology effects].

Antinutritional factors (ANFs) protect the seed against attacks of moulds, bacteria, insects and birds. The defensive effect of ANFs is apparently related to disturbances in digestive processes in insects and microorganisms. When animals consume seeds containing ANFs, the digestive processes and growth may be disturbed in a similar manner. In the present paper, the fact is discussed that all proteins passing undigested through the small intestine will be fermentatively digested in the large intestine. The final products of the protein digested in the large intestine are excreted in the faeces or urine. For investigations into the digestion of protein in pigs and the amounts of N excreted into the environment, it is of importance to measure the ileal digestibility of protein. Studies showed that ANFs such as trypsin inhibitors, lectins and tannins present in legume seeds reduce the ileal digestibility of protein. In the case of Phaseolus beans it was found that more protein passed through the terminal ileum than was ingested with the feed. With peas was shown that ANFs reduce the ileal digestibility of protein. The carbohydrates of peas did not affect the ileal digestibility of protein, although the ileal chyme was more loose. In the case of faba beans, negative correlation of tannins with ileal digestibility of protein was observed. Calculations showed that, when ANFs were removed from peas and faba beans a considerable reduction in excretion of N into the environment can be achieved. These calculations also showed important possibilities of reducing the secretion of N into the environment by elimination of ANFs.

Animal Feed↗
PubMed2006

The effect of a fructo-oligosaccharide supplemented formula on gut flora of preterm infants.

AIM: The intestinal flora of breast-fed infants is generally dominated by bifidobacteria which have beneficial properties. Their presence is due to various components of breast milk, including prebiotic substances. This prospective double-blind study compared the numbers of bifidobacteria in the stool flora of bottle-fed preterm infants randomized to receive for 14 days either a formula with prebiotic fructo-oligosaccharides at a concentration of 0.4 g/dL or the same formula with maltodextrin as a placebo. METHODS: Within 0-14 days after birth, 56 healthy bottle-fed infants were enrolled to receive either the prebiotic or placebo. Faecal samples were taken at inclusion day and at study day 7. The number of bifidobacteria in the stools, stool characteristics and somatic growth were recorded during the study. RESULTS: In the group fed fructo-oligosaccharides, both the numbers of bifidobacteria in the stools and the proportion of infants colonized with them were significantly higher as compared to the placebo group (p=0.032 and p=0.030 respectively). There was also a higher number of bacteroids in the fructo-oligosaccharide group as compared to the placebo (p=0.029). At the same time, reduction was noted in the numbers of Escherichia coli and enterococci. (p=0.029, and p=0.025, respectively). Supplementation had also significant influence on stool frequency per day (p=0.0080). CONCLUSION: An infant formula containing a small quantity of prebiotic oligosaccharides is well accepted and leads to rapid growth of bifidobacteria in the gut of bottle-fed preterm infants while decreasing the numbers of pathogenic microorganisms.

Bifidobacterium↗
PubMed2004

Oral delivery of pathogens from the intestine to the nervous system.

Most therapeutic agents are delivered orally. Consequently, the major classes of therapeutically useful chemicals are partially lipophilic, small molecular weight compounds. They have reasonable permeability coefficient values across cell membranes, including those of intestinal epithelia and vascular endothelia. In contrast, large molecular weight biotechnology compounds have limited usefulness by non-injected routes as a consequence of their low membrane permeability and variable solubility. However, a wide range of infectious agents have developed strategies or have hijacked physiological routings in order to enter the host by the oral route. Efforts to address such issues have refreshed interest in mechanisms by which different types of payloads (including particulates and microorganisms) translocate across gut epithelia and then distribute to target tissues. Special attention is given to the potential role of the enteric nervous system and its plasticity.

Administration, Oral↗
PubMed2006

Gut-associated bacterial microbiota in paediatric patients with inflammatory bowel disease.

BACKGROUND: Clinical and experimental observations in animal models indicate that intestinal commensal bacteria are involved in the initiation and amplification of inflammatory bowel disease (IBD). No paediatric reports are available on intestinal endogenous microflora in IBD. AIMS: To investigate and characterise the predominant composition of the mucosa-associated intestinal microflora in colonoscopic biopsy specimens of paediatric patients with newly diagnosed IBD. METHODS: Mucosa-associated bacteria were quantified and isolated from biopsy specimens of the ileum, caecum and rectum obtained at colonoscopy in 12 patients with Crohn's disease, 7 with ulcerative colitis, 6 with indeterminate colitis, 10 with lymphonodular hyperplasia of the distal ileum and in 7 controls. Isolation and characterisation were carried out by conventional culture techniques for aerobic and facultative-anaerobic microorganisms, and molecular analysis (16S rRNA-based amplification and real-time polymerase chain reaction assays) for the detection of anaerobic bacterial groups or species. RESULTS: A higher number of mucosa-associated aerobic and facultative-anaerobic bacteria were found in biopsy specimens of children with IBD than in controls. An overall decrease in some bacterial species or groups belonging to the normal anaerobic intestinal flora was suggested by molecular approaches; in particular, occurrence of Bacteroides vulgatus was low in Crohn's disease, ulcerative colitis and indeterminate colitis specimens. CONCLUSION: This is the first paediatric report investigating the intestinal mucosa-associated microflora in patients of the IBD spectrum. These results, although limited by the sample size, allow a better understanding of changes in mucosa-associated bacterial flora in these patients, showing either a predominance of some potentially harmful bacterial groups or a decrease in beneficial bacterial species. These data underline the central role of mucosa-adherent bacteria in IBD.

Adolescent↗