Seroepizootiology of Helicobacter pylori gastric infection in nonhuman primates housed in social environments.

We determined the seroepizootiology of Helicobacter pylori infection in rhesus monkeys. Plasma was obtained from 196 animals (age range, 1 to 22 years) that were housed in social environments, either in indoor gang cages, in outdoor corrals, or in free-ranging forested conditions. Plasma immunoglobulin G levels were determined with a specific enzyme-linked immunosorbent assay, and the cutoff immunoglobulin G value for H. pylori seropositivity was determined from a study of 25 monkeys whose infection status was assessed by light microscopy and culture. One-year-old animals of both genders in all housing conditions had the lowest rate of positivity (60% in monkeys 1 year old versus 81% in monkeys 2 to 10 years old, P = 0.026). In addition, females tended to have higher rates of positivity than males. Seroconversion during a 1-year observation period occurred in 7 (28%) of 25 seronegative animals. Seroreversion occurred in 3 (4%) of the 78 positive animals; all 3 of these animals had received antimicrobial agents during the year. These observations demonstrate that the epizootiology of H. pylori infection in rhesus monkeys may serve as a model for human infection.

Effects of cage beddings on microsomal oxidative enzymes in rat liver.

The purpose of the present studies was to evaluate the effects of some commercially available cage beddings on rat liver microsomal cytochrome P-450-dependent drug-metabolizing enzyme, ethylmorphine N-demethylase, and the carcinogen-metabolizing enzyme, benzo(a)pyrene hydroxylase. Sprague-Dawley rats were housed in cages containing cedar chip, corncob or heat-treated pinewood bedding for 3 weeks. Control rats were housed in cages on wire bottom floors containing no bedding material. Rats housed in cages containing cedar chip showed 18, 46 and 49% increases in liver cytochrome P-450 content, ethylmorphine N-demethylase and benzo(a)pyrene hydroxylase activities, respectively. The liver enzyme activities of rats housed in cages containing corncob bedding were similar to those obtained with control rats. In contrast, the pinewood-bedded rats showed a 21% decrease in ethylmorphine N-demethylase activity without affecting cytochrome P-450 content and benzo(a)pyrene hydroxylase activity. Hexobarbital-induced sleep times of the variously bedded rats were similar to those of control animals. These data suggest that the commercial bedding materials differ in their abilities to affect liver microsomal enzymes. Thus, interlaboratory variability in basal enzyme activities reported in the literature may be partly due to bedding materials used in the animal's cages.

Use of vascularized abdominal wall pedicle flaps to grow small bowel neomucosa.

Growing new mucosa from remnants of small bowel remaining in patients with short-bowel syndrome might offer a strategy for solving this clinical problem. We have performed a series of experiments investigating the possibility of growing rabbit ileal mucosa on vascularized pedicle flaps of abdominal wall musculature based on the inferior epigastric artery. By patching a defect of distal ileum with a skeletal muscle flap, we were able to demonstrate bowel augmentation by neomucosal ingrowth. Light and scanning electron microscopy confirmed the presence of essentially normal mucosa with well-developed villi atop the skeletal muscle pedicle flap. The mucosa was stripped from the skeletal muscle and compared with stripped mucosa from adjacent ileum in the Ussing chamber in 11 rabbits. The electrophysiologic studies showed no significant difference between normal mucosa and neomucosa in short-circuit current (Isc), potential difference or tissue conductance. The addition of 10 mM glucose resulted in similar unidirectional glucose flux and increase in Isc in both tissues. Bile salt absorption was also similar in both tissues. We conclude that neomucosa can be grown on flaps of skeletal muscle and is similar to normal mucosa by microscopic and electrophysiologic evaluation.