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PubMed2004

[The parietal mucin microbial population in different sections of the human gastrointestinal tract].

Microbiological examinations of the human-colon parietal mucin were made in different sections of the human gastrointestinal tract (GIT). Biopsy samples of the human colon mucus tunic were used as the research material. Convincing data were found by research on the importance of the anatomic-and-morphological factor in shaping-up of microbiocenosis of the colon-wall parietal mucin. It was established that, depending on a GIT section, not only the quantitative and qualitative composition of normal microflora but also the nature of inter-microbe interactions are subject to changes. In particular, biopsy materials of the small-intestine parietal mucin are much different from that of the colon. The colon section from the ascending colon to the sigmoid colon has, with some exceptions, an identical microbial composition. At the same time, the rectum is significantly different from other colon sections. The results are suggestive of the below cluster-type pattern of parietal biological material: microorganisms are clustered as small domains with certain specific and quantitative compositions. It was established that, although feces and parietal mucin have a similar species composition of microorganisms, still, there is a number of essential differences between them in as far as the frequency ratio and the microorganism concentration are concerned, which signifies a certain degree of isolation of the above biopsy materials. Finally, a certain isolation degree of the feces biopsy materials and of the parietal ones was established.

Bacteria↗
PubMedDate not supplied

The role of lactoferrin in the nonspecific immune response on the ocular surface.

Lactoferrin is an iron binding glycoprotein which is abundantly present in human tear fluid. It is also present in other secretions and in the specific granules of the polymorphonuclear leucocyte. The main biological properties of lactoferrin can be ascribed to its very strong binding of iron cations. Receptors for lactoferrin have been found in the intestinal brush border, suggesting that it may play a role in iron absorption from the gut. Macrophages also have a receptor for lactoferrin, which are possibly involved in the transfer of iron to ferritin. More important may be the fact that deprivation of iron from the gut or from the ocular surface limits the availability of iron to microorganisms and thus exerts firm control of the bacterial flora at these sites. Sequestration of iron by this protein can also inhibit the iron catalyzed production of hydroxyl radicals thereby protecting mucosal surfaces from oxydative damage. Lactoferrin has furthermore been shown to play a role in myelopoiesis, primary antibody response, lymphocyte proliferation, cytokine production, ADCC, NK cell activity, and regulation of complement activation. The observations described above indicate that lactoferrin, besides control of the bacterial flora, may regulate inflammatory reactions occurring on the ocular surface.

Animals↗
PubMed2005

[Surveillance of commensal flora evolution and infections in neutropenic cancer patients submitted to chemoprophylaxis].

The evolution of the flora and its resistance to different antimicrobials in neutropenic patients submitted to high-dose chemotherapy with autologous blood stem-cell transplantation, and the relation of these findings to the etiology of the infections the patients developed was studied in order to evaluate the suitability of the chemoprophylaxis and the empirical antibiotic therapy used. Forty-one patients were analyzed in a period of 28 months. The chemoprophylaxis used was levofloxacin, fluconazole and acyclovir. The empirical sequential treatment was an initial administration of cefepime, followed by teicoplanin and amikacin. Cultures were done of nasal and pharyngeal smears, Hickman catheter and stools, 1 day before chemoprophylaxis started and then on days 5 and 9. In the case of fever, three sets of blood cultures and urine cultures were done and samples from areas related to the clinical condition were analyzed. Levofloxacin induced the selection of resistant strains or species in the flora and in the infectious agents. Fluconazole also selected resistant species in the flora. Seventeen infections were documented in eleven patients, produced by Gram-positive bacteria in thirteen cases (81.25%) and by Gram-negative bacteria in three (18.75%). The coagulase negative staphylococci and Enterococcus faecalis were the most frequent agents of infection. We identified on nine occasions the same microorganism in the flora and in the pathological product; this suggests its endogenous origin and supports the use of prospective cultures of the flora, monitoring the sensibility of the microorganisms isolated to the antimicrobials used in chemoprophylaxis and empirical treatment.

Anti-Bacterial Agents↗
PubMed1978

Relation between the faecal concentration of various potentially pathogenic microorganisms and infections in individuals (mice) with severely decreased resistance to infection.

Lethally irradiated conventional mice were killed at daily intervals after irradiation. A high correlation was found between the occurrence of bacterial overgrowth in the digestive tract and invasion into the regional lymph nodes the spleen and the blood. By oral contamination of mice with quite high doses of either an exogenous or an endogenous biotype of an Enterobacteriaceae species at day 4 after irradiation, it was attempted to induced such condition of intestinal overgrowth. In all animals such an abnormal colonization of the contaminant was indeed achieved in this way and the mice died from an infection caused by the biotype used for the contamination. The interval between contamination and death was different when different biotypes were used for contamination and occurred sooner after irradiation when an endogenous biotype was used for (re)contamination. It is concluded that oral contamination with exogenous as well as with endogenous potentially pathogenic bacteria during a period of severely decreased resistance to infections must be avoided. The colonization resistance of the digestive tract of these animals should be maintained as high as possible.

Animals↗
PubMed2001

[Probiotics: Is there a scientific basis for their effects?].

Probiotic microorganisms have been used with increasing frequency in nutrition and for therapeutic purposes during the last years. Their application is generally based upon empirical experiences, since their mode of action has been the topic of investigations only recently. It became apparent that probiotics exert a wide spectrum of different effects ranging from direct antagonism against pathogens to influence upon intestinal epithelium and immune system of the host's organism. In this review, the current knowledge is summarized.

Digestive System↗
PubMed1996

Guinea pig intestinal phospholipase B: protein expression during enterocyte maturation and effects of N-oligosaccharide removal on enzymatic activities and protein stability.

Guinea pig phospholipase B (PLB) is an intestinal brush-border hydrolase displaying a broad substrate specificity towards various dietary lipids. PLB was detected by immunoblotting as a single 140-kDa polypeptide in all cell populations isolated from guinea pig intestinal mucosa, but increased in parallel to its activity from undifferentiated to mature cells, the specific activity of the enzyme remaining constant. Moreover, N-glycosylation, which contributed to 23% of the apparent molecular mass, was identical along the cell differentiation axis. In all cell fractions, N-linked sugar chains were of the complex type, since they were removed by N-glycosidase F, whereas PLB remained insensitive to endoglycosidase H. Moreover, lack of O-glycosylation was demonstrated by the insensitivity of PLB to O-glycosidase and by its failure to interact with Helix pomatia lectin after prior treatment with neuraminidase or alpha-fucosidase. Enzymatic removal of sugar chains reduced phospholipase A2, lysophospholipase and diacylglycerol lipase activities by 27-35%, kinetic analysis indicating a decrease in apparent Vmax values for the three enzymatic activities, whereas the Km remained unchanged. Finally, the carbohydrate-depleted form of PLB did not display gross changes in thermal stability, in contrast to PLB from microorganisms previously investigated. Our data indicate that the high level of PLB N-glycosylation is poorly related to its biological function. Whether carbohydrate chains are involved in proper targeting of the enzyme to the brush-border membrane remains to be established.

Animals↗
PubMed1996

Quantitative determination of H2-utilizing acetogenic and sulfate-reducing bacteria and methanogenic archaea from digestive tract of different mammals.

Total number of bacteria, cellulolytic bacteria, and H2-utilizing microbial populations (methanogenic archaea, acetogenic and sulfate-reducing bacteria) were enumerated in fresh rumen samples from sheep, cattle, buffaloes, deer, llamas, and caecal samples from horses. Methanogens and sulfate reducers were found in all samples, whereas acetogenes were not detected in some samples of each animal. Archaea methanogens were the largest H2-utilizing populations in all animals, and a correlation was observed between the numbers of methanogens and those of cellulolytic microorganisms. Higher counts of acetogens were found in horses and llamas (1 x 10(4) and 4 x 10(4) cells ml-1 respectively).

Acetates↗
PubMed1979

Membrane glycoproteins shed in defence of the cells of the gastrointestinal tract.

The cells lining the gastrointestinal tract are exposed to various potentially harmful agents, including plant lectins and microorganisms. It is proposed that glycoproteins within the mucus layer of the gut protect against these agents. A hypothesis is presented that membrane glycoproteins are shed and, within the mucus close to the cell surface, block the binding of lectins or attachment of microorganisms to membrane receptors. A model is presented that demonstrates that such blocking can be achieved by soluble glycoproteins. The implications of this hypothesis in health and disease are discussed.

Bacterial Physiological Phenomena↗
PubMed1984

The intestinal microflora of infants: composition of fecal flora in breast-fed and bottle-fed infants.

The fecal flora of 35 breast-fed and 35 bottle-fed babies was determined. Bifidobacteria were the predominant fecal bacteria in both groups. Conversely, the counts of most of the other bacteria, such as bacteroides, eubacteria, peptococci, veillonella, clostridia, enterobacteria, streptococci, and bacilli in the bottle-fed group were significantly higher than those in the breast-fed group. The frequencies of occurrence of lecithinase positive clostridia, clostridia-others, pseudomonas and bacilli in the bottle-fed group were significantly higher than those in the breast-fed group. Twenty-one genera and 103 species or biovars of microorganisms were isolated from the feces of the breast-fed group and 20 genera and 97 species or biovars from the bottle-fed group. The organism that showed the highest number and the highest frequency of occurrence in both groups was Bifidobacterium breve. Bifidobacterium infantis, which was formerly the most prevalent Bifidobacterium species in baby feces, was never isolated in this study. Further, the counts and incidences of Clostridium paraputrificum, C. perfringens, and Bacillus subtilis, the counts of C. clostridiiforme, Bacteroides vulgatus, Veillonella parvula, Lactobacillus acidophilus, Escherichia coli, Streptococcus bovis, S. faecalis, and S. faecium and the incidences of C. difficile, C. tertium, and Pseudomonas aeruginosa in the bottle-fed infants were significantly higher than those in the breast-fed infants.

Bacteria↗
PubMed1997

Biochemical properties of regulatory peptides derived from milk proteins.

Biologically active peptides derived from milk proteins are inactive within the sequence of the precursor proteins but can be released by enzymatic proteolysis. Based on structure-activity studies, peptides with a defined bioactivity show common structural features. Moreover, many milk protein-derived peptides reveal multifunctional bioactivities. Bioactive peptide fragments originating from milk proteins should be taken into account as potential modulators of various regulatory processes in the body. Opioid peptides are opioid receptor ligands with agonistic or antagonistic activities. Angiotensin converting enzyme (ACE) inhibitory peptides can exert an antihypertensive effect. Immunomodulating casein peptides have been found to stimulate the proliferation of human lymphocytes and the phagocytic activities of macrophages. Antimicrobial peptides have been shown to kill sensitive microorganisms. Antithrombotic peptides inhibit the fibrinogen binding to a specific receptor region on the platelet surface and also inhibit aggregation of platelets. Casein phosphopeptides can form soluble organophosphate salts and may function as carriers for different minerals, especially calcium. In relation to their mode of action, bioactive peptides may reach target sites (e.g., receptors, enzymes) at the luminal side of the intestinal tract or after absorption, in peripheral organs. The physiological significance of bioactive peptides as exogenous regulatory substances is not yet fully understood. Nevertheless, several bioactive peptides derived from milk proteins have been shown to exert beneficial physiological effects. Milk-derived peptides were already produced on an industrial scale and as a consequence these peptides have been considered for application both as dietary supplements in "functional foods" and as drugs.

Adjuvants, Immunologic↗
PubMed1993

Influence of lactoferrin on the entry process of Escherichia coli HB101 (pRI203) in HeLa cells.

Lactoferrin (Lf) is an iron-binding protein which plays an important role in the host defense systems of different mucosal surfaces including the intestinal mucosa. In the present research the role of apo-Lf and iron-saturated Lf in the invasion process of enteroinvasive bacteria, grown in iron stress or excess, was investigated. As enteroinvasive bacterium, Escherichia coli HB101 strain harboring a plasmid which contains the chromosomal inv gene from Yersinia pseudotuberculosis was utilized. The product of this gene (invasin) enables this microorganism to invade human epithelial cultured cells (HeLa). The results obtained showed that apo-Lf and iron-saturated Lf added at physiological concentration during the infection exerted a significant inhibition of adhesion (3.2 x 10(5) instead 3.4 x 10(6) adherent bacteria grown in iron excess; 1.6 x 10(3) instead of 2.3 x 10(4) adherent bacteria grown in iron-limited medium) and internalization (4.0 x 10(5) instead of 3.7 x 10(6) internalized bacteria grown in iron excess; 2.1 x 10(3) instead 2.8 x 10(4) internalized bacteria grown in iron-limited medium). It has also been demonstrated that in these experimental conditions Lf binds to HeLa cell membrane as well as to bacterial outer membrane. It is likely that this binding interfere with the early events of interaction between bacteria and eukaryotic cells. This inhibiting effect of Lf on the invasion efficiency of E. coli HB101 (pRI203) could be related to the cationic nature of the molecule, although other mechanisms cannot be ruled out.

Adhesins, Bacterial↗
PubMed2002

Effect of heat-treated proteins on selected parameters of the biotransformation system in the rat.

The intake of heat-damaged proteins from food causes various effects, like the loss of essential amino acids and a reduced protein digestibility. There is also an influence on gastrointestinal microorganisms and different digestion enzymes. Until now, very little is known about the influence of heat-treated proteins on the enzymes of the biotransformation system. In the present study, the influence of protein-bound L-lysino-D,L-alanine, N(epsilon)-fructoselysine, and N(epsilon)-carboxymethyllysine (CML) on selected enzymes of the biotransformation in liver, kidney, and intestinal mucosa of male Wistar rats was examined. The contents of cytochrome P-450 and cytochrome b(5) and the activity of NADPH-cytochrome c reductase served as indicators of phase I biotransformation. The influence on phase II biotransformation was shown by the content of glutathione and the glutathione S-transferase activity. The results showed that treatment with heat-damaged proteins mainly affected phase II biotransformation enzymes with CML, yielding the strongest effect. The activity of glutathione S-transferase in the kidney was 86% higher in animals treated with diets containing 4,930 mg.kg(-1) protein-bound CML than in animals of the control group which received a diet without any detectable CML. In addition, a higher level of glutathione was found in the kidneys of animals fed on diets containing CML. The glutathione S-transferase activity was 64% higher in the intestinal mucosa of animals fed on protein-bound N(epsilon)-fructoselysine (2,700 mg.kg(-1)). The glutathione S-transferase activity was higher (p >0.05) in the intestinal mucosa of animals fed on protein-bound L-lysino-D,L-alanine (2,582 and 12,474 mg.kg(-1)). In conclusion, ingestion of heat-treated proteins led to an activation of the enzymes of phase II biotransformation. Whether or not the released pure compounds or the degradation products of the test proteins are responsible for the altered enzyme activities remains to be evaluated.

Animals↗
PubMed2004

[Bacteria and their role in allergic diseases].

From the beginning of life, human immune system is affected by interactions with different microorganisms. Immediately after the birth bacteria colonize mucous tissues and namely the gastrointestinal tract, which was antenatally sterile. Bacteria are involved in allergic inflammation by two different ways. They can either initiate the allergic response or they can diminish it. To the negative factors, which can trigger the allergic response belong superantigens, namely the bacterial enterotoxins. Positive factors include mycobacterial antigens, intestinal microflora, pathogen-associated molecular patterns and CpG motives that belong to components of the bacterial genome DNA. The effect of lipopolysaccharide from gram-negative bacteria on the development of allergic inflammation is two faced. Lipopolysaccharide has a protective role when the infection precedes the contact with allergen for a long time. Short period between the infection and allergen exposition leads in a sensitized person to the provocation of allergic disease. These and other factors are important in relation to the so-called hygiene hypothesis where the T regulatory lymphocytes seem to play the key role in the balance between Th1 and Th2 lymphocytes.

Bacteria↗
PubMed1985

Inflammatory bowel disease.

The place of inflammatory bowel disorders in the spondarthritis matrix has been discussed and aetiopathological and clinicoradiological features of their individual arthropathies described. Particular emphasis has been placed on the arthropathies of ulcerative colitis and Crohn's disease, but a comment is also included on the much rarer condition, Whipple's disease. The position of reactive arthritis resulting from enteric infection in relation to the spondarthritis concept is examined in the light of Reiter's-like clinical features and the association with HLA-B27. More 'peripheral' ideas of possible relevance to the spondarthritis idea (drug-induced colitis, intestinal-bypass syndrome) are included, together with a final section on experimental models of inflammatory bowel disease and of their arthropathies. It is concluded that certain inflammatory bowel disorders deserve a continuing place within the spondarthritis complex. Although their aetiopathogenesis is still imperfectly understood, it is likely that a blend of genes of small effect (polygenic inheritance) and environmental factors (e.g. microorganisms and/or their products) trigger disease processes which are enabled to manifest themselves by intermediary immunological processes. The precise way in which this is achieved is not yet known, but there is evidence that microorganisms (presumably in the gut of individuals genetically predisposed and suitably exposed environmentally) generate the formation of immune complexes. It is likely that these not only damage or further damage the mucosal lining of the bowel but also result in arthropathy and features of the disease 'distant' from bowel and joint (e.g. ocular inflammation, oral ulceration and skin manifestations). This concept is summarized in Figure 5.

Adult↗
PubMed2001

Bacterial translocation in clinical intestinal transplantation.

BACKGROUND: Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after small bowel transplantation (SBTx). Bacterial overgrowth, alteration of the mucosal barrier function as a consequence of preservation injury or acute rejection (AR), and potent immunosuppression are all associated with BT. The aim of this study was to evaluate and quantify the correlation of BT with these events. METHODS: Fifty pediatric SBTx recipients on tacrolimus and prednisone immunosuppression were analyzed. Blood, stool, and liver biopsies and peritoneal fluid were cultured (circa 4000 total specimens) when infection was clinically suspected or as part of follow-up. BT episodes were considered when microorganisms were found simultaneously in blood or liver biopsy and stool. RESULTS: BT (average of 2.0 episodes/patient) was evident in 44% of patients and was most frequently caused by Enterococcus, Staphylococcus, Enterobacter, and Klebsiella. The presence of a colon allograft was associated with a higher rate of BT (75% vs. 33.3%). Furthermore, the transplantation procedure (colon vs. no colon) affected the rate of BT: SBTx=40% vs. 25%, combined liver and SBTx=100% vs. 30%, multivisceral transplantation=25% vs. 50%. AR was associated with 39% of BT episodes. BT followed AR in 9.6% of the cases. In 5.2% of the cases, positive blood cultures without stool confirmation of the bacteria were seen. Prolonged cold ischemia time (CIT) affected BT rate significantly (CIT>9 hr 76% vs. CIT<9 hr 20.8%). CONCLUSIONS: This study shows that 1) a substantial percentage of, but not all, BT is associated with AR, 2) the presence of a colon allograft increases the risk for BT, and 3) a long CIT is associated with a high incidence of BT after SBTx.

Acute Disease↗
PubMed1997

CD95 (APO-1/Fas)-mediated apoptosis in colon epithelial cells: a possible role in ulcerative colitis.

BACKGROUND & AIMS: Ligation of CD95 (APO-1/Fas) by antibody or CD95 ligand (CD95L) induces apoptosis and, in some cell lines, growth. Normal colonic epithelial cells constitutively express CD95. The function of CD95 on colonocytes is unknown. The aim of this study was to elucidate the role of epithelial CD95 in the normal colon and in ulcerative colitis. METHODS: Intact colonic crypts were isolated, and the effects of CD95 ligation in vitro were studied. CD95L-expressing cells and apoptotic cells were detected in situ by RNA hybridization, immunohistochemistry, and DNA nick end labeling. RESULTS: On CD95 ligation, isolated colonic crypt cells underwent apoptosis within 4 hours. No growth-promoting effect was observed. In normal colon, CD95L expression was restricted to few mononuclear cells randomly scattered within the lamina propria. Therefore, the CD95-CD95L system is very unlikely to operate in the regeneration of the colonic epithelium. However, in ulcerative colitis, the number of interstitial CD95L+ cells and the frequency of apoptosis in both lamina propria and epithelium were increased considerably. Further, a focal association of subepithelial CD95L+ mononuclear cells and epithelial apoptosis was observed. CONCLUSIONS: In ulcerative colitis, soluble CD95L-mediated epithelial apoptosis may lead to a breakdown of the epithelial barrier function facilitating the invasion of pathogenic microorganisms.

Apoptosis↗
PubMed2006

Effects of a Lactobacillus casei synbiotic on serum lipoprotein, intestinal microflora, and organic acids in rats.

The main aim of this study was to evaluate the effectiveness of 3 synbiotic diets: 1) containing Lactobacillus casei ASCC 292 and fructooligosaccharides (LF diet); 2) containing L. casei ASCC 292 and maltodextrin (LM diet); and 3) containing L. casei ASCC 292, fructooligosaccharide, and maltodextrin (LFM diet) to reduce serum cholesterol in male Wistar rats. The effect of the synbiotic diets on intestinal microflora, concentration of organic acids, and the possibility of translocation of lactobacilli were also investigated. The LFM diet lowered serum total cholesterol and triglyceride levels, whereas the LM diet increased serum high-density lipoprotein cholesterol level. However, synbiotic diets did not contribute to a change in low-density lipoprotein cholesterol level compared with the control diet. There was a decrease in the population of staphylococci, bacteroides, Escherichia coli, and total coliforms in most bowel regions with the LFM diet compared with the control (which did not contain any synbiotic). In general, the LFM diet contributed to a higher concentration of lactic acid that may have contributed to the decrease in the population of pathogenic microorganisms compared with the control. Fructooligosaccharide was the preferred substrate for production of acetic acid. Results from this study showed that the synbiotic diet that contained L. casei ASCC 292, fructooligosaccharide, and maltodextrin beneficially altered cholesterol levels and produced a healthier bowel microbial population without translocation of lactobacilli to other organs.

Acetic Acid↗
PubMed1979

Lipolytic enzymes in bovine thyroid tissue. III. Lysophospholipase activity.

Lysophospholipids are formed during phospholipid breakdown as a result of the action of phospholipases A. At certain concentrations these lysoderivatives destabilise biological membranes. Therefore, their concentration is of critical importance for membrane integrity. Prevention of lysophosphoglycerides accumulation may be the important role for lysophospholipases and is probably the explanation for their widespread occurrence in nature. Lysophospholipase activities were found in molds (Fairbairn, 1948), rice bran (Contardi & Ercoli, 1933), several microorganisms (Brockerhoff & Jensen, 1974), snake and bee venoms (Doery & Pearson, 1964; Mohamed et al., 1969; Shiloah et al., 1973), insects (Khan & Hodgson, 1967; Rao & Subrahmanyam, 1969), fish muscle (Yurkovski & Brockerhoff, 1965; Cohen et al., 1967) and in various animal tissues (Marples & Thompson, 1960). In mammalian tissue the enzyme was first described in beef pancreas (Shapiro, 1953). Relatively high levels were detected in intestine, lung, spleen, liver and pancreas, while lower levels were present in muscle, kidney, testes, brain and blood (Marples & Thompson, 1960). The presence of lysophospholipase activity in both supernatant and sediment of bovine thyroid was reported previously in relation to possible interference of this enzyme with the phospholipase A activity assay (De Wolf et al., 1976). The subcellular localization of bovine thyroid lysophospholipase and some properties of the membrane bound enzyme activity are discussed in this paper.

Animals↗