Biomedical subjects

D H Ringler

Publications and source records attributed to D H Ringler.

32 records · Page 2Linked to original sources

PubMed1978

Age-associated pathological changes in male rats.

The selection of rats for aging research and the interpretation of experimental results require knowledge of spontaneous age-associated lesions in specific stocks and strains. We have compared selected age-associated pathological changes, as determined by postmortem examination of 113 outbred Crl:CD(SD)BR male retired breeder rats 12--39 months old, with those reported by others in a group of 122 virgin male 12- to 33-month-old F344 rats, an inbred strain from the same commercial source as the outbred rats. Numerous degenerative, inflammatory, and neoplastic lesions occurred in both groups. The wide prevalence and severity of many of the lesions suggest that they could be the source of significant variability in the results of specific aging studies, by their direct and indirect effect(s) on target organs. The prevalence of spontaneous lesions should be defined for each stock or strain intended for use in aging research by postmortem examination of representative groups of animals at various ages. Antemortem diagnostic screening of old rats may also be useful in culling animals bearing lesions that could add to the variability of experimental results, or in selecting for specific lesions that are of research interest themselves.

Aging↗

PubMed1978

Characterization of Pasteurella multocida isolates from the nares of healthy rabbits with pneumonia.

Pasteurella multocida was isolated from 42 of the 135 (31%) deep nasal swabs from clinically healthy conventional rabbits supplied by two vendors. The prevalences were significantly different among sex, age, and sources. The females and adults had higher prevalences when compared to males and juveniles, respectively. One vendor's rabbits had a prevalence of 41% while the other had 20%. Biochemically, only 24% of the 42 isolates decarboxylated L-ornithine, and 55% produced indol. All isolates were sensitive in vitro to several of the commonly used antibiotics, but most isolates were resistant to lincomycin, streptomycin, and sulfonamides. Typing with a hyaluronidase inhibition test revealed that 28 of the 42 (67%) isolates were type A. Type A was the major type isolate, whether the samples came from healthy rabbits or from rabbits with pyogenic lesions. The acriflavine flocculation test showed that two of the 42 (5%) isolates were type D. Although none of the 42 isolates were positive to both hyalurondase and acriflavine tests, 12 of the 42 (29%) isolates were negative to both tests, indicating that these isolates were not typeable by these two methods. The demonstration of more than one capsular type of Pasteurella multocida in rabbits indicates the need for more extensive studies on this important rabbit pathogen.

Acriflavine↗

PubMed1977

Spontaneous malignant histiocytoma with metastasis in a rhesus monkey [Macaca mulatta].

A malignant histiocytoma was observed on the left arm of a recently imported rhesus monkey. Rapid invasion of deep tissues and tumor growth on the face prompted euthanasia. Necropsy revealed additional neoplastic foci in the lungs, diaphragm, intercostal muscles, pericardium and liver. Microscopically the predominant cell type was histiocytic; some cells had a distinct epithelioid appearance and other were spindle-shaped.

Animals↗

PubMed1976

Failure of commercially prepared isoniazid diet to produce isoniazid serum concentrations in rhesus monkeys.

A comparison was made of serum isoniazid concentrations and the time course of isoniazid elimination in rhesus monkeys given the drug im, orally on sugar cubes, or in a commercially medicated diet. When the drug was administered orally on sugar cubes or im, peak serum concentrations were usually reached within 2 hr. A threefold individual variation in the rate of elimination was noted, and in most animals the serum concentration at 6 hr approached zero. Isoniazid was not detected in the serum of any animal receiving the commercially medicated diet. Others using this medicated food in their tuberculosis prophylaxis programs should be aware that the diet probably does not provide therapeutically effective dosage to the animals.

Administration, Oral↗

PubMed1975

Fever and survival.

The significance of fever in response to a bacterial infection has been investigated using the lizard Dipsosaurus dorsalis as an animal model. These lizards develop a fever of about 2 degrees C after injection with the bacterium Aeromonas hydrophila. To determine whether this elevation in body temperature increases the resistance of the host to this infection, as measured by survival, lizards were infected with the live bacteria and placed in a neutral (38 degrees C), low (34 degrees or 36 degrees C), or high (40 degrees or 42 degrees C) ambient temperature. An elevation in temperature following experimental bacterial infection results in a significant increase in host survival.

Aeromonas↗

PubMed1974