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PubMed1987

Mechanisms of peptide transport.

This review touches on the development of the concept of transmembrane transport of peptides, which originated more than 100 years ago, and discusses present knowledge of the phenomenon, with special reference to intestinal absorption of peptides. It deals with (1) Peptide transport in animal small intestine and its main features--active transport of di- and tripeptides into the absorptive cells, the question of sodium or proton dependence of peptide transport, the independence of peptide and amino acid transport, competition for transport between peptides, the number of transport systems involved, the influence of molecular structure on peptide transport, transport kinetics and relative rates of absorption of peptides and amino acids, nutritional and therapeutic aspects of peptide transport, mechanisms of absorption of small peptides of dietary origin and mechanisms of absorption of biologically active peptides (2) Peptide transport in other animal cells and tissues (3) Peptide transport in microorganisms (4) Peptide transport in higher plants and (5) Physiological advantages of peptide transport. The concluding remarks stress that though most of the salient features of peptide absorption may have been established by 1975, more investigators might usefully be engaged in studying the many remaining questions concerning peptide transport in the animal body, and point out the unfortunate effects of too narrow an approach to problems in the field.

Amino Acids↗
PubMed1974

Surface-surface associations in microbial communities populating epithelial habitats in the murine gastrointestinal ecosystem: scanning electron microscopy.

Scanning electron microscopy has been used to visualize the residents of microbial communities populating habitats on epithelial surfaces in the gastrointestinal tracts of mice. In the stomach, bacteria form a dense layer on the stratified squamous epithelium of the nonsecreting area. Microbes of at least three morphological types can be seen in this layer, including short rods with round ends, rods in chains, and tapering filaments composed of repeating units of rod- or coccal-shaped elements varying in size from large at one end of the filament to small at the other end. These three forms all attach by one end to the epithelium. The latter two forms can be found only so attached; in both cases, the end is inserted into a hole or depression in the keratinized epithelium. In the small intestine, a microbe of morphology similar to that of the tapering filaments found in the stomach can be seen attached end-on to the epithelium. Again each filament has one end inserted into a hole in the epithelium. In this case, however, the repeating elements of each filament are all about the same size. In the cecum and colon, predominantly fusiform- and spiral-shaped microbes can be seen mixed together in layers on the epithelium. At least three types of fusiform-shaped microbes can be distinguished on the basis of surface texture, and one type of spiral-shaped microbe can be found. These microorganisms appear to be attached to each other and to the epithelium by weblike filaments. The numerous microbial types present in the various epithelial habitats associate intimately surface-to-surface with each other and with the epithelium. Such surface-surface association may be an important autogenic factor contributing to the stability of the murine gastrointestinal ecosystem.

Animals↗
PubMed1996

Barriers to application of genetically modified lactic acid bacteria.

To increase the acceptability of food products containing genetically modified microorganisms it is necessary to provide in an early stage to the consumers that the product is safe and that the product provide a clear benefit to the consumer. To comply with the first requirement a systematic approach to analyze the probability that genetically modified lactic acid bacteria will transform other inhabitants of the gastro- intestinal (G/I) tract or that these lactic acid bacteria will pick up genetic information of these inhabitants has been proposed and worked out to some degree. From this analysis it is clear that reliable data are still missing to carry out complete risk assessment. However, on the basis of present knowledge, lactic acid bacteria containing conjugative plasmids should be avoided. Various studies show that consumers in developed countries will accept these products when they offer to them health or taste benefits or a better keepability. For the developing countries the biggest challenge for scientists is most likely to make indigenous fermented food products with strongly improved microbiological stability due to broad spectra bacteriocins produced by lactic acid bacteria. Moreover, these lactic acid bacteria may contribute to health.

Consumer Behavior↗
PubMed2004

Tolerance of probiotics and prebiotics.

The clinical efficacy of probiotics and prebiotics has been proved in several clinical settings. The authors review their proved or potential side effects. Probiotics as living microorganisms may theoretically be responsible for 4 types of side effects in susceptible individuals: infections, deleterious metabolic activities, excessive immune stimulation, and gene transfer. Very few cases of infection have been observed. These occurred mainly in very sick patients who received probiotic drugs because of severe medical conditions. Prebiotics exert an osmotic effect in the intestinal lumen and are fermented in the colon. They may induce gaseousness and bloating. Abdominal pain and diarrhea only occur with large doses. An increase in gastroesophageal reflux has recently been associated with large daily doses. Tolerance depends on the dose and individual sensitivity factors (probably the presence of irritable bowel syndrome or gastroesophageal reflux), and may be an adaptation to chronic consumption.

Bifidobacterium↗
PubMed1979

Prediction of the protein requirements of farm ruminants and implications of these predictions for diet formulation.

Methods of determining protein requirements are reviewed and recent proposals of the Agricultural Research Council working party on nutrient requirements of ruminants outlined. Needs of the rumen microorganisms for degradable nitrogen to achieve optimum rumen digestion of feed are predicted. The extent to which milk production and live-weight gain can be sustained by microbial protein alone is estimated. Higher milk yields and rates of growth require dietary protein that escapes degradation in the rumen but is digested in the small intestine. Small changes in degradability of dietary protein are predicted to have a large effect on the dietary crude protein requirement. Although there is still inadequate data for precise prediction, the concepts of the metabolic approach have been valuable in understanding those physiological situations where protein is most likely to be limiting, where use of protected proteins and urea might be most appropriate, in the planning of critical experiments and in the design of new methods of feeding or management of ruminants.

Animal Feed↗
PubMed2003

Microecology as a target for therapeutic intervention in inflammatory bowel disease.

The gastrointestinal tract is populated by several hundred grams of bacteria. Recognition of the symbiosis between bacteria and host is drawing particular attention to the implications of bacteria in human health. Probiotics are living microorganisms that upon ingestion in certain numbers exert health benefits. Prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth or activity of a limited number of gut bacteria. In inflammatory bowel disease (IBD), the gut flora is the key factor driving the inflammatory process that leads to intestinal lesions. Interaction of certain commensal bacteria with the gut mucosa triggers mucosal inflammation. However, certain probiotic strains are able to downregulate inflammatory pathways. Restoring the microbial balance with prebiotics and probiotics offers promise for the control of IBD.

Animals↗
PubMed1983

Colonization of gnotobiotic mice by Roseburia cecicola, a motile, obligately anaerobic bacterium from murine ceca.

In scrapings of mouse cecal mucosae, motile bacteria outnumbered nonmotile bacteria by a ratio of 2:1. Obligately anaerobic bacteria were obtained from such scrapings through the use of techniques designed for the selective isolation of motile bacteria. One of the isolates, Roseburia cecicola, was rapidly motile in broth by means of 20 to 35 flagella arranged in a fascicle on each cell. R. cecicola cells colonized germfree mice (3 x 10(9) to 1 x 10(10) CFU/g of cecum) within 11 days after the animals were inoculated intragastrically with 2 x 10(8) CFU per mouse. In such monoassociated gnotobiotes, the bacteria were found primarily in the cecum, dispersed in the lumen among particles of digesta, and in the mucus over the epithelial surface. Between 2 and 3 weeks after birth, offspring of monoassociated adult mice were colonized by the bacterium (2 x 10(9) to 1 x 10(10) CFU/g of cecum). These results indicate that R. cecicola is suitable for studies of the ecology of host-associated microorganisms, particularly for investigation of the role of motility and possibly also chemotaxis in bacterial colonization of the mammalian gastrointestinal tract.

Anaerobiosis↗
PubMedDate not supplied

[The use of a bioprofile of Escherichia for its epidemiological marking].

The analysis of the penetrating and expressing capacity of the markers of bacterial persistence, adhesive capacity, antibiotic resistance and colicinogenicity in 254 E.coli strains of 7 groups, isolated from different ecotopes, including different environmental objects and bodies of healthy and sick children, revealed the specific character of their population bioprofiles, i.e. complexes of phenotypical signs of microorganisms. The results of the cluster analysis carried out with regard to the totality of data on E.coli bioprofiles made it possible to detect two clusters: the first cluster included pathogenic E.coli isolated from children with pathogenic processes, the second one included non-pathogenic E.coli isolated from healthy children and from aqueous objects. The levels of the information content of individual signs of microorganisms were determined and the use of E.coli bioprofiles for their epidemiological marking was substantiated.

Analysis of Variance↗
PubMed2002

[Extra-intestinal Manifestations of chronic inflammatory Bowel diseases].

Approximately one third of all patients with Crohn's disease and ulcerative colitis suffer from extra-intestinal manifestations of their inflammatory bowel disease. Most commonly those symptoms occur simultaneously with the CED symptoms; they can, however, either precede them or appear later on in the course of the disease. The most frequent extra-intestinal symptoms are arthralgias of peripheral joints and spine, which are usually bland and self-limiting, while ankylosing spondylitis and erosive arthritides are rare. Skin lesion and eye affections can also parallel the bowel condition, but occasionally they precede intestinal manifestations and can be a first diagnostic clue. In addition, different extra-intestinal symptoms tend to simultaneously co-occur more frequently in some patients with CED, while others are not affected at all. Immunogenetic parameters play a role for the manifestations of the pathologic immune response both in the gut and in the musculo-skeletal systems, as indicated by associations with MHC class I alleles. Enteropathic microorganisms are also thought to be involved in the pathogenetic mechanisms.

Arthritis↗
PubMed2005

Distinct gene expression profiles characterize cellular phenotypes of follicle-associated epithelium and M cells.

Follicle-associated epithelium (FAE) covering Peyer's patches contains specialized epithelial M cells that take up ingested macromolecules and microorganisms from the lumen of the gut by transcytosis. Using high-density oligonucleotide microarrays, we analyzed the gene expression profiles of FAE and M cells in order to characterize their cellular phenotypes. The microarray data revealed that, among approximately 14,000 genes, 409 were expressed in FAE at twofold or higher levels compared to the intestinal epithelial cells (IECs) of the villi. These included genes involved in membrane traffic, host defense and transcriptional regulation, as well as uncharacterized genes. Real-time PCR and in situ hybridization analyses identified three molecules, ubiquitin D (Ub-D), tumor necrosis factor receptor superfamily 12a (TNFRsf12a), and transmembrane 4 superfamily 4 (Tm4sf4), which were predominantly distributed throughout FAE, but were expressed little, if at all, in IECs. By contrast, transcripts of secretory granule neuroendocrine protein 1 (Sgne-1) were scattered in FAE, and were co-localized with Ulex europaeus agglutinin-1 (UEA-1)-positive cells. This clearly suggests that expression of Sgne-1 in the gut is specific to M cells. Such a unique pattern of gene expression distinguishes FAE and M cells from IECs, and may reflect their cellular phenotype(s) associated with specific functional features.

Animals↗
PubMed1988

[Influence of the oral administration of indigenous microorganisms on the resistance of mice to Salmonella infection].

The influence of the oral administration of killed bifidobacteria, lactobacteria, bacteroids and fusobacteria on the anti- Salmonella resistance of mice, infected orally with S. dublin, was studied. Bifidobacteria and lactobacteria were shown to produce a dose-dependent immunostimulating effect. The oral administration of killed bifidobacteria and lactobacteria led to the enhanced resistance of mice to Salmonella infection. The oral administration of killed bifidobacteria was conductive to the normalization of the intestinal microflora in dysbacteriosis developing in cases of Salmonella infection. Bacteroids and fusobacteria were found to possess no such effect.

Administration, Oral↗
PubMed2005

Red wine polyphenols influence carcinogenesis, intestinal microflora, oxidative damage and gene expression profiles of colonic mucosa in F344 rats.

Polyphenols from tea and other beverages such as red wine have been regarded with interest as possible chemopreventive agents against cancer. Here we report that red wine polyphenols (50 mg/kg) administered with the diet to F344 rats for 16 weeks inhibited colon carcinogenesis induced by azoxymethane (AOM, 7.4 mg/kg, total dose 74 mg/kg) or dimethylhydrazine (DMH, 30 mg/kg, total dose, 300 mg/kg). Polyphenol-treated animals had a consistently lower tumour yield compared to controls. In polyphenol-treated rats, the main bacterial strains in the faeces at sacrifice were Bacteroides, Lactobacillus and Bifidobacterium spp., whereas microorganisms predominantly identified in control-fed rats were Bacteroides, Clostridium and Propionibacterium spp. Wine polyphenols (57 mg/kg for 10 days, by gavage), administered to rats not treated with carcinogens, produced a significant decrease in the basal level of DNA oxidative damage of the colon mucosa as measured with the comet assay (average pyrimidine oxidation was reduced by 62% and purine oxidation by 57%, p<0.05). To further explore the molecular effects of wine polyphenols we used the microarray technology to study gene expression profiles: rats were treated with 50 mg/kg wine polyphenols for 14 days, mixed in the diet. Global expression analysis of 5707 genes revealed an extensive down-regulation of genes involved in a wide range of physiological functions, such as metabolism, transport, signal transduction and intercellular signalling. By analysing metabolic pathways with the GenMAPP software program we observed that two major regulatory pathways were down-regulated in the colon mucosa of polyphenols-treated rats: inflammatory response and steroid metabolism. We also found a down-regulation of many genes regulating cell surface antigens, metabolic enzymes and cellular response to oxidative stress. In conclusion, reduction of oxidative damage, modulation of colonic flora and variation in gene expression may all concur in the modulation of intestinal function and carcinogenesis by wine polyphenols.

1,2-Dimethylhydrazine↗
PubMed1979

[Pathogenicity of aerobically sporulating microorganisms: Bacillus cereus].

The pathogenicity of the metabolites of B. cereus was determined by bioassays with white mice, chick embryos, rabbits, and kittens. Cell-free filtrates of the cultures of several strains of B. cereus were used for application; in the mice the application was done i. v., i. p. and p. o., in the chick embryos via the allantoic sac, in the kittens p. o. and i. p., in the rabbits via tied-up sections of the small intestine by the loop-test method. It was revealed that some strains of B. cereus produced substances of exotoxin nature under suitable conditions. White mice and chick embryos were the best materials for their detection.

Animals↗
PubMed2001

[Microbiological contamination of intraoperatively collected erythrocyte concentrate in mechanical autotransfusion in tumor surgery].

Intraoperative autotransfusion is an effective method of the autologous haemotherapy. Gamma irradiation of the salvaged erythrocyte concentrates leads to inactivation of malignant cells and allows retransfusion in oncologic surgery. The risk of microbiological contamination of the autologous blood product has not been systematically studied in this field of surgery. During the evaluation of intraoperative autotransfusion in oncologic surgery at the University Hospital of Leipzig, the salvaged blood of 46 patients who underwent tumour surgery (urology, gynaecology and neurosurgery) was processed to a washed erythrocyte concentrate with a Cell Saver 5 or a Haemolite 2 (Haemonetics). Specimens for microbiological studies were taken from the area of surgery, the reservoir bottle of the autotransfusion system and the salvaged erythrocyte concentrates. The investigation with plate cultures and the identification of microorganisms were performed according to standard procedures of microbiological diagnosis. The ethics committee of the University Hospital of Leipzig approved the study protocol. We found a microbiological contamination in 10 of 46 salvaged erythrocyte concentrates (22%), above all the growth of saprophytes (Streptococcus, Staphylococcus and Neisseria species). We also identified bacteria which have their habitats in the intestinal tract (E. coli and Enterococcus). The highest rate of microbial contaminated erythrocyte concentrates was found in urologic oncosurgery (37%). In neurosurgery (laminectomy and craniotomy including tumour extirpation), there was no bacterial growth in the salvaged erythrocyte concentrate. Intraoperative autotransfusion should be avoided during surgery touching the urinary tract, e.g. prostatectomy and cystectomy. In neurosurgery, it seems to be safe as far as microbiological contamination is concerned. To assess the real risk of microbiological contamination of the salvaged erythrocytes, more investigations are necessary to determine not only the extent and nature of contamination but also the clinical effects.

Adult↗
PubMed2002

Inhibition of adhesion of enterotoxigenic Escherichia coli K88 by soya bean tempe.

AIMS: Tempe is a traditional fungal fermented food made from soaked and cooked soya beans. It has been associated with antidiarrhoeal characteristics. This study investigated potential inhibitory effects of tempe on enterotoxigenic Escherichia coli (ETEC) K88. METHODS AND RESULTS: Soya beans were soaked, cooked and subsequently fermented using several Rhizopus spp. Water-soluble filter-sterile extracts were tested for their ability to inhibit growth of E. coli and several indicator microorganisms and to inhibit adhesion of ETEC K88. Antimicrobial activity was found against Bacillus stearothermophilus only. ETEC K88-induced haemagglutination of hamster red blood cells was strongly inhibited by a number of tempe extracts and hardly by the cooked soya bean extract. Furthermore, several tempe extracts were able to inhibit adhesion of ETEC K88 to piglet small intestinal brush-border membranes. CONCLUSIONS: Tempe appeared to interfere with ETEC K88 adhesion rather than showing growth inhibitory properties. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicate that tempe could exert an antagonistic effect against ETEC through inhibition of adhesion and might therefore have a protective effect against ETEC K88 infection in pigs. Hence, tempe could have potential to use as a feed supplement in the diet of weaned piglets.

Animals↗
PubMed1998

Biotransformation of monoterpenes, bile acids, and other isoprenoids in anaerobic ecosystems.

Isoprenoic compounds play a major part in the global carbon cycle. Biosynthesis and mineralization by aerobic bacteria have been intensively studied. This review describes our knowledge on the anaerobic metabolism of isoprenoids, mainly by denitrifying and fermentative bacteria. Nitrate-reducing beta-Proteobacteria were isolated on monoterpenes as sole carbon source and electron donor. Thauera spp. were obtained on the oxygen-containing monoterpenes linalool, menthol, and eucalyptol. Several strains of Alcaligenes defragrans were isolated on unsaturated monoterpenes as growth substrates. A novel denitrifying beta-Proteobacterium, strain 72Chol, mineralizes cholesterol completely to carbon dioxide. Physiological studies showed the presence of several oxidative pathways in these microorganisms. Investigations by organic geochemists indicate possible contributions of anaerobes to early diagenetic processes. One example, the formation of p-cymene from monoterpenes, could indeed be detected in methanogenic enrichment cultures. In man, cholic acid (CA) and chenodeoxycholic acid (CDCA), are synthesized in the liver from cholesterol. During their enterohepatic circulation, bile acids are biotransformed by the intestinal microflora into a variety of metabolites. Known bacterial biotranformations of conjugated bile acids include: deconjugation, oxidation of hydroxy groups at C-3, C-7 and C-12 with formation of oxo bile acids and reduction of these oxo groups to either alpha- or beta-configuration. Quantitatively, the most important bacterial biotransformation is the 7 alpha-dehydroxylation of CA and CDCA yielding deoxycholic acid and lithocholic acid, respectively. The 7 alpha-dehydroxylation of CA occurs via a novel six-step biochemical pathway. The genes encoding several enzymes that either transport bile acids or catalyze various reactions in the 7 alpha-dehydroxylation pathway of Eubacterium sp. strain VPI 12708 have been cloned, expressed in Escherichia coli, purified, and characterized.

Bacteria, Anaerobic↗