Determination of fermentable carbohydrate from the upper gastrointestinal tract by using colectomized rats.

The primary aim of this study was to characterize the carbohydrate that would be supplied to the colon for fermentation under physiological conditions. Colectomized rats were fed fiber-free diets or diets containing 5% (wt/wt) gum arabic. Four (fucose, galactose, glucosamine, and galactosamine) of 11 analyzed sugars accounted for 77% of the total sugar in ileal excreta from colectomized rats fed fiber-free diets. The three sugars in gum arabic, rhamnose, arabinose, and galactose, accounted for 84% of the total sugars in gum arabic ileal excreta. Comparisons of the sugar compositions of the ileal excreta, the water-soluble fractions of the excreta, and three gel filtration fractions of the water-soluble material with those of the water-soluble fraction of rat mucosa, the acetone-soluble fraction of pancreas, and pancreatin suggested that the major source of endogenous carbohydrate is mucin. Gum arabic increased the daily excretion of the four mucin-derived sugars (fucose, galactose, glucosamine, and galactosamine) by the colectomized rats from 473 mumol per day to 634 mumol per day. We conclude that mucin is the major endogenous carbohydrate excreted from the upper gut and that gum arabic increases the amount of this endogenous carbohydrate.     

Absorption of 249Bk from the gastrointestinal tract of rats

In experiments with albino mongrel female rats a study was made of the absorption of 249Bk from the gastrointestinal tract after a single per os administration. The bulk of 249Bk (96 per cent) administered either intravenously or per os was mainly deposited in the skeleton and liver. The value of 249Bk absorption from the gastrointestinal tract by days 4 and 8 following administration was 0.05 per cent.     

Gastrointestinal complications of renal transplantation. 1. The upper gastrointestinal tract.

In 95 consecutive cases of cavaderic renal transplantation followed up for 1 to 83 months (mean 23.1 months) 17 complications developed in the upper gastrointestinal tract of 15 patients; these included duodenal ulcer in 12 and gastric ulcer, esophagitis, hemorrhagic gastritis, small-bowel obstruction and small-bowel perforation in 1 each. The occurrence of a complication was not related to the patient''s age, sex, blood group or use of cigarettes or alcohol, the duration of hemodialysis before transplantation, the tissue match or the number of infusions of immunosuppressive medication. One patient died of the complication. The peptic ulcers that developed after transplantation were successfully managed conservatively in 69% of cases. Since surgical treatment in patients whose immune response has been suppressed is associated with an increased frequency of complications such as disruption of suture lines, it is preferable to reserve it for those in whom complications develop that are unresponsive to conservative measures.     

Clinical findings,early endoscopy,and multivariate analysis in patients bleeding from the upper gastrointestinal tract.

A simple system has been developed to identify patients with upper gastrointestinal tract haemorrhage who run a high risk of continued bleeding or rebleeding. The system is based on six items of patient data available at or soon after arrival in hospital. It was evaluated in a prospective study of 66 patients with upper gastrointestinal tract haemorrhage. Over half of the patients classified by the system into a high-risk category either continued bleeding or rebled after apparent cessation (as against one out of 33 patients in the low-risk category). The high-rish group also had a higher mortality (21%) than those in the low-risk group (nil). The addition or subtraction of early endoscopic findings made little difference to the accuracy of prognosis.     

Colonization of the porcine gastrointestinal tract by lactobacilli.

Eight strains of lactobacillus isolated from the porcine gastrointestinal tract were tested for their ability to adhere in vitro to cells collected from stratified squamous epithelium in the digestive tracts of newborn piglets. Piglets were inoculated with individual strains, and their digestive tracts were sampled at intervals to determine the colonizing ability of the lactobacilli. The results of the in vitro test did not predict whether a lactobacillus strain would associate with stratified squamous epithelium in the piglet digestive tract, but epithelial association in vivo appeared to be an important factor in the maintenance of lactobacillus populations in the tract. None of the lactobacillus strains used as inocula was numerically dominant in the tract 7 days after inoculation of the piglets with a single dose of the bacteria.     

Cytologic features of premalignant glandular lesions in the upper gastrointestinal tract

The cytologic findings in 13 endoscopic brushing specimens from biopsy-proven premalignant glandular lesions (PGLs) of the upper gastrointestinal tract were reviewed retrospectively. The specimens were from ten patients: three with dysplasia in Barrett's esophagus, four with gastric adenomas and three with duodenal adenomas. One dysplasia in Barrett's esophagus and four adenomas (two gastric and two duodenal) had coexisting adenocarcinomas. Most pure PGLs were characterized cytologically by cohesive three-dimensional clusters of cells with more-or-less uniformly enlarged nuclei and an increased nuclear/cytoplasmic ratio. Crowding and molding were present within these clusters; however, the cells were arranged in a somewhat orderly or palisading fashion, instead of entirely haphazardly. In cases of carcinoma coexisting with adenoma or dysplasia, the atypical cells tended to be more pleomorphic and dyshesive. In one specimen from an adenocarcinoma arising in an adenoma, the adenomatous and carcinomatous components could be distinguished cytologically.     

Biotransformation of arsenobetaine by microorganisms from the human gastrointestinal tract

Abstract

The consumption of fish and shellfish is a major route of human exposure to arsenic (As), because they contain relatively large concentrations of organoarsenicals, in particular arsenobetaine (AB). AB is considered non-toxic because of its rapid excretion from the human body. However, previous studies on human metabolism and excretion of AB have used the compound in solution rather than considering the effects that occur during the digestion of food in the gastrointestinal tract. In this preliminary study, we used microcosms inoculated with human faecal matter to investigate the aerobic and anaerobic degradation of AB by microorganisms associated with the large intestine. Samples were recovered over 30 days, centrifuged, filtered and the supernatant analysed for total As content and As speciation, using ICP–MS and HPLC–ICP–MS respectively. After 7 days the total As in the supernatants from the aerobic experiment fell to a minimum of 65% of the total added, recovering to 15% less than added after 30 days. By using anion and cation exchange chromatography coupled to ICP–MS detection, arsenobetaine (AB), dimethylarsinic acid (DMA), dimethylarsinoylacetic acid (DMAA) and trimethylarsine oxide (TMAO) were identified as degradation products. Results from the aerobic system showed that after 7 days incubation the AB had been degraded to DMA, DMAA and TMAO and after 30 days the degraded AB reappeared in the samples. The results for the anaerobic system showed no degradation of AB over the 30 day course of the experiment. These findings demonstrate for the first time that biocatalytic capability for AB degradation exists within the human gastrointestinal tract.     

The release of fermentable carbohydrate from peat by steam explosion and its use in the microbial production of solvents

Steam treatment of peat at 200 degrees C for 3 min, followed by instantaneous decompression (steam explosion), solubilized up to 28% of the dry matter. Seventy-five percent of the solubilized material was carbohydrate, 33% of which was composed of mono- and disaccharides, including galactose, glucose, xylose, mannose, arabinose, and cellobiose, in order of decreasing concentration. The solubilized materials served as the sole source of carbohydrate for growth and solvent production by Clostridium acetobutylicum and C. butylicum which utilized up to 40% of the carbohydrate. Of the saccharides in this mixture, galactose was the least readily utilized. Approximately 30% of the fermentable carbohydrate used was converted to fatty acids and solvents, with the primary fermentation product being butyrate. Clostridium thermohydrosulfuricum was able to utilize ca. 50% of the carbohydrate, and simultaneously produced slightly more than 1 mol ethanol/mol saccharide metabolized. This organism, like other strains tested, used galactose less readily than the other sugars. The residue from the steam explosion process contained 24% cellulose, but it could not serve as a source of carbohydrate for the growth of either Bacteroides succinogenes or Clostridium thermocellum, suggesting that inhibitors were released during the steam treatment.     

Taste receptors in the gastrointestinal tract. V. Acid sensing in the gastrointestinal tract

Luminal acidity is a physiological challenge in the foregut, and acidosis can occur throughout the gastrointestinal tract as a result of inflammation or ischemia. These conditions are surveyed by an elaborate network of acid-governed mechanisms to maintain homeostasis. Deviations from physiological values of extracellular pH are monitored by multiple acid sensors expressed by epithelial cells and sensory neurons. Acid-sensing ion channels are activated by moderate acidification, whereas transient receptor potential ion channels of the vanilloid subtype are gated by severe acidosis. Some ionotropic purinoceptor ion channels and two-pore domain background K(+) channels are also sensitive to alterations of extracellular pH.     

Reduction of nitroaromatic compounds by anaerobic bacteria isolated from the human gastrointestinal tract.

Human intestinal microbial flora were screened for their abilities to reduce nitroaromatic compounds by growing them on brain heart infusion agar plates containing 1-nitropyrene. Bacteria metabolizing 1-nitropyrene, detected by the appearance of clear zones around the colonies, were identified as Clostridium leptum, Clostridium paraputrificum, Clostridium clostridiiforme, another Clostridium sp., and a Eubacterium sp. These bacteria produced aromatic amines from nitroaromatic compounds, as shown by thin-layer chromatography, high-pressure liquid chromatography, and biochemical tests. Incubation of three of these bacteria with 1-nitropyrene, 1,3-dinitropyrene, and 1,6-dinitropyrene inactivated the direct-acting mutagenicity associated with these compounds. Menadione and o-iodosobenzoic acid inhibited nitroreductase activity in all of the isolates, indicating the involvement of sulfhydryl groups in the active site of the enzyme. The optimum pH for nitroreductase activity was 8.0. Only the Clostridium sp. required added flavin adenine dinucleotide for nitroreductase activity. The nitroreductases were constitutive and extracellular. An activity stain for the detection of nitroreductase on anaerobic native polyacrylamide gels was developed. This activity stain revealed only one isozyme in each bacterium but showed that the nitroreductases from different bacteria had distinct electrophoretic mobilities.