Biomedical subjects

A E Avots-Avotins

Publications and source records attributed to A E Avots-Avotins.

5 recordsLinked to original sources

PubMed1990

Day and night esophageal motor function.

Circadian rhythmic variation has been documented in gastric, small bowel and colonic motility. Morning and evening studies of esophageal motility were performed to assess whether similar rhythmicity exists in esophageal function. Fifteen healthy male subjects were studied twice on separate study days. Esophageal manometry was performed either at 10 AM or 10 PM after a standardized meal given 10 h prior to each study. Lower esophageal sphincter pressures, distal esophageal contractile amplitudes, distal esophageal contractile durations, and the velocity of propagation of peristaltic waves in the proximal and distal esophagus were measured. No significant differences were detected in esophageal function between day and night studies. These findings suggest either 1) nocturnal slowing of gastrointestinal motility is not a generalized characteristic of the entire GI tract, or 2) a two time-point study is not adequate to detect a true circadian rhythm in esophageal motor function.

Adult↗

PubMed1982

Evaluation of bacterial attachment to acid treated bladder epithelium.

The technique of rapid (60 seconds) acid treatment of intact rat bladders was used to evaluate bacterial interactions with bladder mucin and mucosal cells. Using the rat model system, SEM indicated that short term acid treatment removed the mucin layer but it also modified the bladder epithelial cell surface. Although the treatment which removed mucin allowed an increase in random bacterial attachment, the increase could also be attributable to acid modification of the mucosa. Examination of acid treated rabbit bladders also showed mucin removal and simultaneously bladder epithelium modification. We conclude that short term acid treatment removes mucin, modifies the epithelial layer, and appears to nonspecifically increase bacterial attachment on the mucosa by modifying the mucosal surface.

Animals↗

PubMed1981

Evidence for a bladder cell glycolipid receptor for Escherichia coli and the effect of neuraminic acid and colominic acid on adherence.

The rat bladder epithelial cell receptors involved in mannose-sensitive adherence of Escherichia coli strains were studied. Sodium metaperiodate and lipase pretreatment of epithelial cells significantly reduced bacterial adherence to cells whereas trypsin and phospholipase C had a marginal or insignificant effect on adherence. Neuraminidase and colominic acid significantly increased adherence, whereas N-acetylneuraminic acid significantly reduced adherence. These data suggest that the rat bladder epithelial cell receptors involved in mannose-sensitive adherence are glycolipids. In addition, the data suggested that sialic acid on bladder epithelial cells acts as a nonspecific inhibitor of adherence, whereas colominic acid, a component of some E. coli K1 capsules, may act as a promoter of adherence.

Animals↗

PubMed1981

Environmental alteration and two distinct mechanisms of E. coli adherence to bladder epithelial cells.

We used an in vitro model to investigate Escherichia coli attachment to transitional epithelial cells obtained from bladders of female rats. Adhesive abilities and sensitivity to mannose inhibition differed among the isolates for both epithelial cells and erythrocytes. Adherence of some strains could be modulated by bacterial washes and growth media. Variations in adhesiveness were related to bacterial piliation as determined by transmission electron microscopy. With two strains, mannose inhibition of adherence to epithelial cells was dose-related; however, with a maximal inhibitory dose, adherence was reduced by approximately 80 per cent even when the bacteria-to-epithelial cell ratio was varied. These studies show that adhesiveness and piliation of certain adhesive E. coli strains are either reduced or enhanced by environmental alterations. We conclude that E. coli strains adhere to epithelial cells by at least two distinct mechanisms and that a single isolate may utilize both mechanisms. The more efficient process is pili-mediated and inhibited by mannose whereas undetermined surface components mediate the less efficient but mannose-resistant mechanism.

Animals↗

PubMed1979

Evidence for pili-mediated adherence of Klebsiella pneumoniae to rat bladder epithelial cells in vitro.

The possible role of pili in the pathogenesis of urinary tract infections caused by Klebsiella pneumoniae was studied in an in vitro mixture of a phosphate-buffered saline suspension of rat bladder epithelial cells and phosphate-buffered saline-washed K. pneumoniae. Nonpiliated and piliated populations derived from a single K. pneumoniae strain were obtained by controlling the total time of growth in broth medium. The piliated phase demonstrated a significant increase in adherence when compared to the nonpiliated phase. Incubation of the bacteria and epithelial cell mixture at 4 and 37 degrees C resulted in no differences in adherence; optimal adherence occurred at pH 5. Pretreatment of the bacteria with enzymes to destroy the pili resulted in a decrease in adherence, as did killing the bacteria by various means before adherence testing. Pretreatment of the epithelial cells with certain saccharides inhibited bacterial adherence. Finally, a 96% decrease in adherence was observed after coincubation of bacteria and epithelial cells with papain-treated antipili antibodies. Thus, it appears that pili on the surface of K. pneumoniae mediate attachment of the bacteria to rat bladder epithelial cells.

Adhesiveness↗