PubMed Health⌕ Search

Biomedical subjects

R A Prentiss

Publications and source records attributed to R A Prentiss.

4 recordsLinked to original sources
PubMed1984

Gastrointestinal transit in thyroid disease.

Diarrhea and malabsorption are common manifestations of hyperthyroidism, whereas constipation or obstipation frequently occur in hypothyroidism. Abnormalities of gastrointestinal motility have been proposed as the primary cause of these complaints, but documentation has been conflicting and largely limited to observations of the transit time of a barium meal. We studied gastrointestinal transit time in fasting patients with thyroid dysfunction using the pulmonary excretion of H2 after the ingestion of a nonabsorbable carbohydrate, lactulose, as an indicator of the rate of transit to the colon. Mean transit time of 10 hyperthyroid patients (29 +/- 4.0 min) was significantly less than that of 42 healthy controls (72 +/- 3.7 min, p less than 0.001), and of 6 hyperthyroid patients when they became hypothyroid after treatment (80 +/- 11.0 min, p less than 0.05). Transit time decreased significantly when hypothyroid patients were given thyroid replacement (p less than 0.01). These findings support the hypothesis that abnormal gut motility may be the primary cause of the diarrhea and malabsorption of hyperthyroidism, and the constipation and obstipation commonly seen in hypothyroidism.

Adult↗
PubMed1982

Metabolism of carbon monoxide by the colonic flora of humans.

The metabolism of carbon monoxide by the colonic flora was investigated using human fecal homogenates. During anaerobic incubation, these homogenates rapidly consumed added carbon monoxide reducing the PCO level to a minimum of about 0.2 ppm. In the presence of glucose, carbon monoxide consumption averaged about 0.7 ml/h . g feces and without glucose about 0.2 ml/h . g feces. This consumption was not observed if the homogenates were autoclaved, passed through a bacterial filter, or cultured aerobically, indicating that the carbon monoxide was removed by the metabolism of fecal anaerobes. Aerobic incubation of fecal homogenates resulted in slow but definite release of carbon monoxide. While bacterial carbon monoxide consumption probably does not play an appreciable role in the turnover of carbon monoxide that is inhaled or exogenously produced, it is possible that carbon monoxide uptake by colonic flora protects other fecal organisms and possibly the host from carbon monoxide liberated in the gut.

Aerobiosis↗
PubMed1980

The effect of anesthesia and laparotomy on blood flow to the stomach, small bowel, and colon of the dog.

The effect of anesthesia and laparotomy on the distribution of blood flow to the different tissue layers of the stomach, small bowel, and colon of the dog was studied using a double-isotope, microsphere technique. In conscious dogs total jejunal flow significantly exceeded both ileal and colonic flow. Mucosal flow comprised about two thirds of total gastric and small bowel flow, but less than half of colonic flow. Fifteen minutes after induction of anesthesia, there was a marked increase in flow to all levels of the alimentary tract, as well as to each tissue layer. This increase was transient, since by 1 hour flow to all gut levels had decreased nearly to baseline levels. Laparotomy per se did not significantly alter blood flow to the full thickness or mucosal layer of either stomach, small bowel, or colon. These findings indicate that future studies of gut function or blood flow should be performed in conscious animals or in anesthetized animals only after complete cardiovascular stabilization. Neither laparotomy nor anesthesia caused a redistrubtion of flow away from the mucosal layers, and hence the observation that patients have often stopped bleeding at the time of operation for uncontrolled hemorrhage is unexplained.

Anesthesia, General↗