PubMed Health⌕ Search

Biomedical subjects

A Vince

Publications and source records attributed to A Vince.

11 recordsLinked to original sources
PubMed1986

Whipple's disease with unusual clinical, bacteriologic, and immunologic findings.

A middle-aged man was found to have Whipple's disease after episodes of nephritis and arthralgia. While on antibiotic therapy, and in the absence of worsening of the histologic appearances of the jejunum, aortic valve endocarditis developed, presumably due to Whipple's disease. Observations during the course of his illness included the isolation of Corynebacterium bovis from an inguinal lymph node, and detection of circulating antibodies against material within the characteristic abnormal macrophages present in the gastrointestinal mucosa. This antigen-antibody reaction was specifically blocked by the monosaccharide rhamnose, a component of the polysaccharide surface coat of many bacteria, including C. bovis.

Antibody Formation↗
PubMed1978

Effect of lactulose on ammonia production in a fecal incubation system.

An in vitro fecal incubation system was used to demonstrate how lactulose influences ammonia metabolism in the colon. Lactulose and other fermentable substrates (glucose, mannitol, and sorbitol), pH and organic acid were varied independently so that their different effects could be determined. Fermentable substrate caused a fall in ammonia concentration during the period of fermentation. Acidification to pH 5.0 or less, with hydrochloric acid or a lactic-acetic acid mixture, significantly reduced ammonia generation, but unlike fermentable substrates, did not lower the existing ammonia concentration. The lactic-acetic acid mixture did not reduce ammonia generation significantly below that found with acidification by hydrochloric acid. The effect of lactulose in reducing ammonia concentration is attributed to its role as a bacterial substrate in either increasing bacterial assimilation of ammonia or reducing deamination of nitrogenous compounds. The effect of low pH in reducing generation of ammonia appears to be part of a general reduction in bacterial metabolism.

Ammonia↗
PubMed1976

Generation of ammonia from non-urea sources in a faecal incubation system.

1. A 25% faecal suspension in sodium chloride solution, incubated anaerobically at 37 degrees C for 48 h, showed excellent survival of all the main groups of faecal bacteria. 2. All faecal incubation systems studied generated large amounts of ammonia, particularly those in which bacterial counts fell during incubation. As normal faeces contain negligible amounts of urea this ammonia must have been generated from sources other than urea. 3. Ammonia was also generated by faeces delivered by sodium chloride enema, and by ileostomy fluid, indicating that the phenomenon is not confined to distal colonic contents. 4. Ammonia generation by incubated faeces was inhibited by prior autoclaving of the sample, but not by sterilization with gamma-irradiation. 5. Generation of ammonia by incubated stool was accompanied by release of large amounts of organic anion and a fall in pH. 6. These observations are interpreted as evidence that ammonia generated within the colon in situ is not derived exclusively from urea, but also from bacterial deamination of amino acids, peptides and proteins. Simultaneously bacterial activity generates large amounts of organacid. The presence of living bacteria is not essential for ammonia generation, provided that bacterial enzymes are present. 7. Bacterial generation of organic solute in faeces which have left the body is sufficiently rapid to cast serious doubts on the validity of faecal centrifugation, or other time-consuming techniques involving lengthy handling of faeces, as methods of obtaining extracellular faecal fluid for measurements of organic constituents or ammonia.

Adult↗
PubMed1973

Ammonia production by intestinal bacteria.

Bacterial growth and the production of ammonia from urea and by deamination of peptone has been examined at various pHs in both conventional static bacterial cultures and in a continuous cultivation system. Growth occurred on primary testing of 93 out of 100 strains of aerobic Gram-negative bacteria at pH 5, and 48 out of 50 strains of Esch. coli at pH 4.6. Hydrolysis of urea by Proteus mirabilis decreased steadily from pH 7.2 to pH 5.3; below pH 5.3 little hydrolysis occurred. Ammonia production from peptones by Esch. coli decreased from pH 7.2 to pH 4.6. Considerable variation was noted in the ability of different strains to produce ammonia. Experiments with cultures containing both Esch. coli and Pr. mirabilis showed that more ammonia was produced at low pH than was produced by cultures of single organisms. At low pH reduction in the count of organisms was not found to be an essential prerequisite for reduction of ammonia formation.

Ammonia↗
PubMed1973

The effect of perfusion on the flora of the excluded colon.

The bacterial flora of excluded colonic segments of three patients has been examined in the normal resting state and following perfusion.The flora of the excluded colon was substantial and qualitatively similar to that of faeces. Perfusion for two hours at 10 ml per minute usually reduced counts of organisms present in the issuing effluent by 1 to 1(1/2) logs in two patients, but rises in the counts of some organisms were recorded from the third patient. Prolonged rapid perfusion or the inclusion of antibiotics in the perfusing solution was necessary to obtain a substantial reduction in counts. Rapid perfusion resulted in the appearance of organisms that had not been recovered during slower perfusions.

Bacteroides↗