Biomedical subjects
Publications and source records attributed to G E Rodrick.
Vibrio vulnificus was enumerated in seawater and shellfish from two Florida estuaries at selected seasonal intervals. There were significant fluctuations in the presence and numbers of V. vulnificus. Relatively high seawater temperature and salinity favored the presence of V. vulnificus in both seawater and shellfish samples.
Two strains of Vibrio cholerae serotype O1 Inaba were isolated from eastern oysters, Crassostrea virginica, collected from estuarine waters in Florida during April 1980. The oyster meats and waters from which the oysters were collected had low fecal coliform counts, and the area had no prior evidence of sewage contamination.
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The authors have explored the suitability of the Mongolian gerbil as a model in aging research and reviewed data on major factors in gerbil morbidity and mortality. The gerbil is a semi-desert rodent, introduced relatively recently into biomedical research. It is moderately prolific, has a maximum survival of about 208 weeks and is easily maintained. Maternal neglect, fighting and epidemic diseases (Tyzzer's disease, salmonellosis, pneumonia) are potential causes of mortality in gerbil colonies. Obese or breeding gerbils may exhibit hyperadrenocorticism, diabetes, non-lipoid arteriosclerosis and secondary lesions in several organs. There is a high prevalence of spontaneous neoplasms in aged gerbils, especially tumors of the adrenal cortex, ovary and skin. The gerbil is a useful model of experimentally-induced stroke, but has proven unsuitable for studies of cholesterol-induced atherosclerosis. The normal and pathological anatomy of periodontal disease in the gerbil is similar in many respects to that of man.
A lampyrid larva (Coleoptera) was found during snail collecting in Liberia, West Africa to be a natural predator of Biomphalaria pfeifferi and Bulinus globosus.
We studied the sequence of histopathologic changes associated with Brugia pahangi (Nematoda: Filarioidea) infections in lymphatic vessels in the spermatic cord of the Mongolian jird (gerbil), Meriones unguiculatus. Intravascular granulomas caused mainly by disintegrating worms were seen in 67% of jirds necropsied on, or after, 35 days postinoculation, whereas none of 20 jirds examined before this day showed dying larvae. These granulomas usually evolved without vascular occlusion. Other granulomatous foci, often with a thrombuslike core, sometimes harbored microfilariae or microfilarialike materials. The perilymphatic cellular infiltrate consisted mostly of eosinophils, lymphocytes, and plasma cells. Large numbers of eosinophils were seen in the early weeks, but later declined, while lymphocytes increased to become the predominant cell in old infections. Irregular fibrosis of some valves and portions of the lymphatic walls were seen as early as the 2nd wk postinoculation. Lymphatic changes in the jird are similar to those described in other hosts infected with filariae, but remained moderate. Living worms appeared to be the stimulus for many observed changes. Most pathologic alterations were well established by 3 or 4 mo and showed little qualitative change during the remaining 4 mo of the study.
1. The activities of lysozyme, acid and alkaline phosphatases, beta-glucuronidase, amylase, lipase, glutamate-oxalacetate transaminase, and glutamate-pyruvate transaminase in the whole hemolymph and 4000 g pellets and supernatants of Mya arenaria were determined. 2. All of these enzymes, except for amylase, occurred in whole hemolymph as well as in the 4000 g pellet and supernatant. 3. Based on earlier observations, these enzymes are believed to be of cellular origin within hemolymph cells. 4. In the case of amylase, it only occurred in the whole hemolymph and/or serum and is believed to have originated from the crystalline style.
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Both naturally occurring disease processes and experimental models of human disease in the Mongolian gerbil were reviewed. The gerbil was highly susceptible to cerebral infarction following unilateral ligation of one common carotid artery and was useful in studies of the pathogenesis of stroke. Spontaneous epileptiform seizures mimicked those of human idiopathic epilepsy, and both seizure-sensitive and resistant strains have been bred. Perhaps because of its more efficient nephron, the gerbil accumulated four to six times as much renal lead as the rat, and the gerbil has been proposed as an experimental model of lead nephropathy. On standard diets, about 10% of the animals became obese, and some showed decreased glucose tolerance, elevated serum immunoreactive insulin and diabetic changes in the pancreas and other organs. Some breeders exhibited hyperactivity of the adrenal cortex associated with hyperglycemia, hyperlipidemia and degenerative vascular disease. Although dietary supplements of cholesterol were toxic and did not induce atherosclerosis, the gerbil was useful in other studies of cholesterol absorption and metabolism. Spontaneous, insidious periodontal disease became evident after about 6 months on standard diets, and dental caries were induced by cariogenic diets or by pathodontic streptococci. Spontaneous neoplasia occurred in 8.4--24% of gerbils, usually after 2 years of life. Adrenal cortical, ovarian and cutaneous tumors were the most consistently reported neoplasms.
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