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Biomedical subjects

S C Whipp

Publications and source records attributed to S C Whipp.

6 recordsLinked to original sources
PubMed1979

Inter-relationship of sodium, chloride, bicarbonate and acetate transport by the colon of the pig.

1. Net transport of Na, Cl, HCO3 and acetate was examined in the temporarily isolated colon of conscious pigs weighing 46 +/- 8 kg. 2. The entire colon absorbs 4.1 ml. H2O, 0.8 m-equiv Na, 1.3 m-equiv acetate and secretes 0.5 m-equiv HCO3/min with a solution comparable to the normal contents. The absorptive capacity of the proximal and distal halves of the colon was comparable per unit dry weight of mucosa when each segment was presented with the same solution. 3. A series of studies using ion replacement solutions showed that net Na absorption and net HCO3 accumulation in the lumen solution were both increased in the presence of acetate. Cl absorption was independent of Na absorption and was accompanied by an equivalent net secretion of HCO3 in the absence of Na. When NaCl in the perfusion solution was replaced with Na2SO4, Na and HCO3 were absorbed at equal rates. 4. Final pCO2 values observed in NaCl and Na2SO4 solutions were greater than those observed in plasma while the pCO2 of the Na acetate solution after perfusion was reduced to values below plasma concentrations. 5. Results are consistent with the hypothesis that hydration of CO2 in the lumen solution or mucosal cell provides a continuous source of H ions for absorption of the more permeable undissociated acid. The evidence also suggests an additional source of H ions may be provided by a Na-H exchange process located in one of the limiting cell membranes.

Acetates↗
PubMed1979

Pathogenic synergism between Treponema hyodysenteriae and other selected anaerobes in gnotobiotic pigs.

Gnotobiotic pigs were orally exposed to various anaerobes at 6 to 9 days of age and similarly inoculated with Treponema hyodysenteriae B204 3 to 6 days later. Watery diarrhea and fecal excretion of large quantities of mucus and some fibrin clots were observed 4 to 20 days after inoculation with B204 if other anaerobes were present. Colonic lesions characteristic of swine dysentery were observed when B204 was present with Fusobacterium necrophorum, three strains of Bacteroides vulgatus, a Clostridium species, and Listeria denitrificans individually and when some of these microbes were present in various combinations, but not when B204 was present alone. These results are consistent with the conclusion that T. hyodysenteriae is the primary pathogen in the etiology of swine dysentery and that the presence of one or more other anaerobes is a prerequisite for expression of pathogenicity of T. hyodysenteriae. This prerequisite can be met by a variety of anaerobes.

Anaerobiosis↗
PubMed1978

Effects of age and ambient temperature on the responses of infant mice to heat-stable enterotoxin of Escherichia coli: assay modifications.

The response of infant mice to heat-stable enterotoxin from Escherichia coli was affected by the age of the mice (2, 4, 6, and 8 days) and by the ambient temperature (25, 30, and 37 degrees C) after exposure to the enterotoxin. The younger mice and/or mice held at lower temperatures tended to accumulate intestinal fluid (high gut weight/body weight ratios), but older mice and/or mice held at higher temperatures tended to respond with diarrhea and low gut weight/body weight ratios. The standard infant mouse assay forheat-stable E. coli enterotoxin can be simplified, without loss of sensitivity or reliability, by holding the mice at 37 degrees C after exposure and using diarrhea as the index of response. Diarrhea can be detected easily by incorporating dye in the inocula and (at the end of the assay) checking for dye mixed with feces on the rear quarters of the mice or on a sheet of white paper placed under them during incubation.

Aging↗
PubMed1977

Enterotoxigenic Escherichia coli and diarrheal disease in Mexican children.

Enterotoxigenic strains of Escherichia coli were isolated from eight (16%) of 50 Mexican children admitted to the hospital with diarrhea and from one of 50 children hospitalized for nonenteric disorders. All of the toxigenic strains tested elaborated a heat-labile enterotoxin, and in seven of nine patients no E. coli capable of concomitant production of heat-stable enterotoxin were found. None of the strains of E. coli with classical enteropathogenic serotypes isolated from nine patients with diarrhea produced either heat-labile or heat-stable enterotoxin. Although the results of this study strongly suggest that enterotoxigenic strains of E. coli are probably responsible for a significant number of cases of diarrhea in an indigenous Mexican pediatric population, further proof will require demonstration of in vivo production of enterotoxin and/or antitoxin.

Bacterial Toxins↗
PubMed1977

Reduction of reactivity of Escherichia coli enterotoxins by intestinal mucosal components.

Incubation studies involving rabbit and piglet small intestinal mucosal components and Escherichia coli and Vibrio cholerae enterotoxins were conducted at 37 and 4 degrees C. Mucosal homogenate cytosol from rabbits did not significantly alter the reactivities of either cholera enterotoxin (CT) or E. coli labile enterotoxin (LT). However, mucosal homogenate cytosol from piglets was capable of neutralizing LT, though it had no effect on E. coli stable enterotoxin. LT became bound to piglet and rabbit microvillous membranes at 4 degrees C in the presence of a protective protein. In rabbits, the binding of LT was not dependent upon an intact glycocalyx or free unbound CT-receptors, although some binding was apparently associated with the glycocalyx and CT-receptors. These results indicated the presence of two different LT-receptors in microvillous membranes one being associated with the membrane proper and the other with the glycocalyx. Stable enterotoxin did not bind to in vitro preparations of piglet mucosal components, which is evidence for a different mechanism for inducing intestinal secretion.

Animals↗