PubMed Health⌕ Search

Biomedical subjects

S J Barron

Publications and source records attributed to S J Barron.

28 records · Page 2Linked to original sources
PubMed1985

Susceptibility of male white-tailed deer (Odocoileus virginianus) to Brucella ovis infection.

Infection with Brucella ovis was established by conjunctival instillation in 8 male white-tailed deer (Odocoileus virginianus). Infection was transient in young bucks, but persisted in bucks that were mature when inoculated. The deer were euthanatized and necropsied at various intervals after inoculation. Brucella ovis was recovered from a mature buck at necropsy on postinoculation day 429. Four deer had gross lesions and histopathologic changes of the epididymides. A mature noninfected buck confined for 7 months with an infected buck acquired infection and developed epididymal lesions.

Animals↗
PubMed1984

Demonstration of the inclusion appendage of Anaplasma marginale in nymphal Dermacentor andersoni.

Dermacentor andersoni nymphs were placed in stockinettes and allowed to feed on a splenectomized calf with experimentally induced anaplasmosis when the parasitemia was 3%-5%. Nymphs were selected on each of the 6 days of feeding and every 5 days from repletion through molting to the adult stage (25 days postrepletion); they were killed and midgut tissues were processed and examined by light and electron microscopies. No stages of A marginale were seen in tissues of feeding ticks. Visualization of individual components of gut contents was difficult owing to presence of the concentrated, electrondense blood meal containing hemoglobin. Inclusion appendages were observed in midgut tissues of nymphs at 5 and 10 days postrepletion, but not at 20 or 25 days. The morphology of the appendages was similar to that described for inclusion appendages commonly associated with anaplasmal inclusions in bovine erythrocytes. Some appendages were free in the lumen of the midgut and occurred either alone or with clusters of small vesicular particles. Occasionally, initial bodies like those generally found in bovine erythrocytes were seen with the appendage, but most of them were swollen and appeared to be degenerating. Frequently, inclusion appendages were observed attached to the luminal surface of the midgut cell membrane by a blunt, electron-dense attachment complex. The attachment of the appendage appeared to be extracellular, with the pointed end extending into the lumen. Often, small particles were observed immediately across the cell membrane from where the appendages were attached; the small particles appeared to be generated from the appendage itself and to have passed through the membrane of the midgut cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaplasma↗
PubMed1983

Demonstration of Anaplasma marginale in hemolymph of Dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.

Hemolymph was collected from adult Dermacentor andersoni Stiles that had been infected with Anaplasma marginale Theiler as nymphs. Before hemolymph was collected, the adult ticks were either incubated and unfed at 37 C for 2.5 days or fed for 6 days on sheep. Hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. Smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. Hemolymph from incubated ticks caused anaplasmosis in 2 of 4 trials, and hemolymph from feeding ticks caused anaplasmosis in 4 of 4 trials. Moderately fluorescing bodies were demonstrated in some hemocytes from incubated ticks, whereas hemocytes from feeding ticks contained numerous clusters of brightly fluorescing bodies. Fluorescing bodies were not observed in hemocytes from control ticks.

Anaplasma↗
PubMed1983

Influence of parasitemia level at feeding on development of Anaplasma marginale Theiler in Dermacentor andersoni Stiles.

Four splenectomized dairy calves were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source (donor) for laboratory-reared Dermacentor andersoni Stiles nymphs. Two donor calves developed higher parasitemias during tick feeding than did the 2 other donor calves. One month after molting, adult ticks were incubated at 37 C for 2.5 days to stimulate development of colonies of A marginale, and homogenates of gut were made from ticks fed on each donor calf. Eight susceptible, splenectomized dairy calves (2 per donor calf) were each inoculated IV with the gut homogenates collected from 50 adult ticks and were monitored for patent A marginale infection. Gut tissues from these same groups of ticks were processed for histologic studies. Homogenates from ticks infected on donor calves with lower parasitemias caused infections with longer prepatent periods (av, 43.25 days) than did similar homogenates made from ticks infected by feeding on donor calves with higher parasitemias (av, 31.0 days). Also, sections of gut tissues from ticks infected at the lower parasitemias contained fewer (av, 0.65) colonies/0.001 mm2 of tissue examined than did those from ticks infected at higher parasitemias (av, 6.31).

Anaplasma↗
PubMed1982

Hematologic and serum chemical values of adult female Rocky Mountain elk from New Mexico and Oklahoma.

Hematologic and serum chemical values were determined for two groups of adult female Rocky Mountain elk (Cervus elaphus nelsoni) from New Mexico and Oklahoma. Although considerable variation in values was observed between elk from the same group, the mean values from 16 of the 20 blood parameters tested were significantly different between the two groups. Of these, the most significant variations were observed in values which were likely to be influenced by nutritional condition and health status. The results of this study indicate that when evaluating the health status of different herds kept under known conditions, hematologic and serum chemical values are of optimal significance when the mean values of the herds are compared.

Animal Population Groups↗
PubMed1982

Influence of increased temperature on Anaplasma marginale Theiler in the gut of Dermacentor andersoni stiles.

Three splenectomized dairy calves were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source for laboratory-reared Dermacentor andersoni Stiles nymphs. One month after molting, groups of adult ticks were incubated at 37 C for 0, 1.5, 2.5, and 7 days. Gut homogenates were made from ticks representing each incubation period. Twenty-four susceptible, splenectomized dairy calves were each inoculated IV with a gut homogenate extracted from 50 adult ticks and monitored for patent A marginale infection. The prepatent periods were determined and used as a measure of infectivity. Gut homogenates made from ticks that had been incubated for 2.5 days produced infections with the shortest prepatent periods, an average of 28.5 days among 3 trials.

Anaplasma↗