Biomedical subjects
Publications and source records attributed to R A Dieterich.
A moose (Alces alces gigas) was inoculated with Brucella suis biovar 4 to better understand the effects of brucellosis in this species. Serum antibody titers increased rapidly and peaked within 21 to 56 days. Fever, leukocytosis, recumbency, anorexia and depression were observed starting 42 days post inoculation. Brucella suis biovar 4 was isolated from blood, lymph nodes, liver and spleen.
Dexamethasone was administered to 2 Dall ewes that had clinically recovered from contagious ecthyma in an attempt to reactivate contagious ecthyma in the sheep. Clinical signs of disease were not detected within 24 days after corticosteroid injection, and virus was not detected in tissues collected at necropsy.
Serologic evidence of contagious ecthyma (CE) was found in domestic sheep (Ovis aries), domestic goats (Capra hircus), Dall sheep (Ovis dalli), and musk-ox (Ovibos moschatus) in Alaska. A moose (Alces alces) calf and a caribou (Rangifer tarandus) fawn were susceptible to experimental infection and both developed antibody titers as a result. CE virus was isolated from lesions of Dall sheep which were involved in a natural outbreak of the disease.
The naturally occurring disease caused by San Miguel sea lion virus in fur seals was characterized by small fluid-filled vesicles 1 to 25 mm in diameter on the nonhaired portions of the flippers. Early epithelial lesions contained multifocal sites of cell lysis. The resultant microvesicles enlarged and coalesced, forming grossly visible macrovesicles. Mature vesicles progressed to involve all layers of the epithelium but did not involve the underlying dermis. Intradermal inoculation of vesicular exanthema of swine virus type A48 or San Miguel sea lion virus type 2 into otarid (fur) seal pups caused plaque-like lesions around inoculated coronary bands. These swellings regressed without rupture by 96 hours postinoculation. One seal inoculated with San Miguel sea lion virus had a linear lingual erosion at ten days postinoculation. Virus was isolated from this site and from two uninoculated sites, the tonsil and testicle. Contact controls showed no evidence of infection. Virus was isolated in low titers from some sites of inoculation and draining lymph nodes from seals infected with vesicular exanthema of swine virus. Virus was recovered more easily, in higher titers, and from more tissues, from seals infected with San Miguel sea lion virus. Inoculated seals tested after four to ten days seroconverted. Feeding swine seal tissues from the inoculation experiments resulted in seroconversion in swine which were fed tissues from seals infected with vesicular exanthema of swine virus but not in those which were fed tissues from seals infected with San Miguel sea lion virus.
In 1976 and 1977, a disease resembling contagious ecthyma was seen in captive musk-oxen (Ovibos moschatus) in Alaska. A similar disease occurred in 1977 in captive Dall sheep (Ovis dalli). Paravaccinia viruses were detected by electron microscopy and isolated in cell cultures from both species. Experimental inoculation in susceptible and immune domestic sheep (Ovis aries) plus fluorescent antibody tests with ecthyma-immune conjugate indicated that the isolate was contagious ecthyma virus.
Six seronegative pregnant reindeer (Rangifer tarandus L) were vaccinated with killed Brucella abortus strain 45/20 with added adjuvant. These were challenge exposed with B suis type 4 after 90 days; at the same time, 4 seronegative, nonvaccinated, pregnant reindeer (controls) were given the challenge inoculum. Humoral antibodies were detected in the vaccinated reindeer by postvaccination day 14. A marked increase in antibody levels also occurred after they were challenge exposed, but did not reach the levels observed in control reindeer which seroconverted within 8 days after they were given the challenge inoculum. One control reindeer aborted at 45 days after challenge exposure (at 165 days of a normal 225-day gestation period), and the fawn of another lived only a few days after delivery. Brucella suis type 4 was isolated from tissues of 3 of 4 control reindeer and of 2 of their fawns. All vaccinated reindeer gave birth to live fawns which were culture negative, although 1 fawn lived only a few days. Brucella suis type 4 was isolated from tissues of 1 vaccinated reindeer. Under the conditions of this experiment, killed B abortus 45/20 vaccine provided increased resistance to brucellosis.
Two species of lemmings and two species of voles were fed a high fat, high cholesterol diet for several months. Clethrionomys rutilus had a moderate (2x) rise in serum cholesterol while Microtus oeconomus had a marked increase (5x); Dicrostonyx stevensoni and Dicrostonyx rubricatus had extreme increases (8x and 11x, respectively). Typical lesions of atherosclerosis were observed in all species, but D. rubricatus had significantly more severe lesions. Hepatic fatty infiltration was the principal pathologic lesion found besides atherosclerosis in those test rodents which died spontaneously.
Lesions were noted in 7.0 and 4.4% of mandible pairs collected from the Western Arctic caribou herd of northwestern Alaska in 1959-61 and 1975-77, respectively. The prevalence of mandibular lesions in the 1959-61 collection is believed to be the highest reported in wild caribou herds of North America. The frequency of occurrence of mandibular lesions was highest in caribou 7 years of age and older, and there was a higher prevalence in adult males than in adult females. Trauma, dental abscesses, and periodontal disease were the probably cause of most lesions. Pathogenic bacteria were not isolated from mandibular lesions from an 11 year-old female. Thirty-three of 98 (33.7%) mandibles with lesions were missing one tooth, while ten (10.2%) were missing more than one tooth. The first molar (M1) was the most common tooth lost in association with lesions, although the loss of two or more teeth was more common among premolars than among molars.
No significant lesions of atherosclerosis or other vascular diseases were found in the aorta and coronary arteries of 34 reindeer and 15 caribou (Rangifer tarandus). Serum lipid, phospholipid, cholesterol and triglyceride levels were similar in caribou and reindeer and did not differ greatly from those reported in other ruminants.
Poxvirus infection was diagnosed on the basis of gross and microscopic appearance plus the presence of typical inclusion bodies in a juvenile American green-winged teal (Anas crecca carolinensis) in Alaska. This constitutes the first known report of avian pox in migratory ducks and the first report of poxvirus infection in wild birds in Alaska.
Postnatal changes in the body composition components, namely, body water, fat-free dry solids, and fat, were determined for laboratory-maintained brown lemmings, Lemmus sibiricus. The proportion of body water decreased while the proportion of fat-free dry solids and fat increased from birth to approximately 15 weeks of age. From 20 through 80 weeks of age, the proportions of all body composition components as well as total body weight remained relatively constant. Body composition components were more closely correlated with body weight than with chronologic age. As a function of body weight, body water decreased while fat-free dry solids and fat increased. Body fat was the most variable body composition component as related both to body weight and chronologic age. The von Bertalanffy growth equation and the differential growth equation were used to describe the body composition component data as related to chronologic age and body weight, respectively.
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The collared lemming, Dicrostonyx stevensoni Nelson, possesses special characteristics which make it a useful animal model for the study of hypercholesteremia, atherosclerosis, breast cancer, kidney disease, and other biomedical research problems. Hematologic values for the lemming were similar to those for the laboratory white mouse except for smaller erythrocytes and fewer leukocytes. Organ weights, when compared as a percent of total body parts, differed only slightly from those of white mice. The basal metabolic rate, measured between 25-30 degrees C, was 40% higher than the standard metabolic rate for a mammal of similar size. Litter size at birth averaged 2.8 in captivity. The mean life span of 254 colony-reared lemmings dying from natural causes was 189 da. Growth rate was rapid during the first 2 mo of life, with moderate increases thereafter to an adult weight of approximately 70 g. Husbandry requirements included the use of shavings as litter and facial tissue as nesting material, all of which was changed weekly. Oats, wheat germ, rabbit pellets, carrots, and lettuse were offered as food.