Bennett J. Cohen

Lead: possible toxicity in urban vs rural rats

The degree of lead poisoning in wild rats from two environments has been studied. Wild rats captured in an urban area had markedly elevated tissue lead compared with values in rural rats. This elevation may have been caused by differences in factors affecting absorption of ingested lead or an elevated respiratory exposure to airborne lead, or both, and lead in precipitated dust. Changes in several biologic indexes (depression of delta-amino levulinic acid dehydratase in kidney and red blood cells, presence of renal intranuclear inclusion bodies, and increased kidney weight) confirmed lead-poisoning in urban rats.

Central and hormonal regulation of renin release by baboon kidneys

Abstract Renin release from renal cortical slices of baboon kidneys was measured. It was found that the basal release rate was directly proportional to the renin content. Release was stimulated in a dose-dependent fashion by isoproterenol and was inhibited both by angiotensin II and vasopressin. Maximum inhibition was approximately 30%. Experiments also were done in which angiotensin II and converting enzyme inhibitor were infused into the lateral ventrical of anesthetized baboons. Angiotensin caused a reduction in plasma renin activity (PRA), and converting enzyme inhibitor an increase in PRA, independent of changes in blood pressure.

Elimination of bacteria from dogs with antibiotics

The effect of oral administration of neomycin cephalothin or kanamycin cephalothin on the aerobic intestinal bacterial flora, was studied in dogs maintained under isolation conditions in a conventional animal room. The dogs were successfully freed of aerobic bacteria with both combinations within two to seven days after the start of antibiotic treatment, and were maintained bacteria free for up to 21 days. Decontamination was attained more rapidly in dogs that were bathed in hexachlorophene surgical soap before and during the first and third days of antibiotic treatment. There was no evidence of toxicity from either of the antibiotic combinations. These results indicate that, as with mice and monkeys, decontamination of dogs with oral antibiotics is feasible. The technique is of potential value in preventing endogenous bacterial infections in canine experimental studies involving use of immunosuppressive agents.

Age-Associated Lesions in Barrier-Reared Male Sprague-Dawley Rats: A Comparison Between Hap: (SD) and Crl:COBS[R]CD[R] (SD)Stocks1,6

Age‐associated lesions were characterized in two outbred stocks of barrier‐reared male Sprague‐Dawley rats. Seventy‐two virgin Hap:(SD) between 6–29 months of age and 113 retired breeder Crl:COBS[R]CD[R](SD) between 12–38 months of age were evaluated for the presence of lesions in all major organ systems. Rats of both stocks developed a spectrum of neoplastic, inflammatory and degenerative diseases with highest prevalence in the oldest age groups. In general, the shorter‐lived Hap:(SD) rats had greater incidences and severity of lesions when compared to Crl:COBS[R]CD[R]SD of similar ages. Many of these differences were not apparent when the two stocks were compared over their respective life spans. The study provides baseline pathology data relevant to the use of these rats in gerontologic research.