Biomedical subjects

P R Barrowman

Publications and source records attributed to P R Barrowman.

7 recordsLinked to original sources

PubMed2003

Bovine spongiform encephalopathy.

Early epidemiological studies identified bovine spongiform encephalopathy as a feed-borne infection associated with infected meat-and-bone meal in animal feed. The infection may have derived from scrapie in sheep, a spontaneous genetic mutation in cattle, or a transmissible spongiform encephalopathy in another mammalian species. Experimental work on the risk of transmission has necessarily tried to identify risk materials and their infectivity levels, the nature and size of species barriers, the infectious dose, the route of infection, the strain of the agent and the genotype of the animals at risk. The identification of levels of infection in cattle tissues has aided the removal of risk materials from the human and animal food chains. Maternally associated transmission is unlikely to maintain an outbreak, but the offspring of clinical cases appear to be at greater risk when the rate of food-borne exposure is high. Studies of embryo transfer have not shown infection to be transmitted by this means. While the control measures appeared to be straightforward, compliance has at times proved difficult to enforce and quantify. This has necessitated more extensive prohibitions, aggressive enforcement and thorough auditing of compliance levels.

Animal Feed↗

PubMed1984

Fleece-rot: the epidemiology and significance of the disease in sheep.

Fleece-rot is a disease of sheep manifested by a superficial dermatitis with seropurulent exudation and matting and, in some cases, pigmentation of wool which occurs following periods of excessive wetness. In Australia it is recognised as the most important predisposing factor to body blowfly strike, and as such represents a major loss to the Australian wool growing industry. This review of the literature suggests that there is no reason for the condition not to be intermittently a significant problem under South African conditions. A long term solution to the problem is achieved by the breeding of resistant sheep. Measurement of fleece wettability is possibly the best method of distinguishing resistant from susceptible sheep.

Animals↗

PubMed1979

Lymph node pathology in Trypanosoma brucei-infected sheep.

The temporal sequence of morphological changes occurring in the prefemoral lymph nodes of sheep experimentally infected with Trypanosoma brucei was studied at weekly intervals during the course of infection. Histopathological changes started with lymphoid stimulation which was soon overtaken and masked by intense proliferation of reticulo-endothelial cells. Reticulo-endothelial proliferation resulted in macrophage accumulation, some vascular damage and lymph stasis, varying from insidious to extensive. Reticulo-endothelial activity subsequently decreased and there was an upsurge of proliferative activity in lymphoid tissue. Lymphoid stimulation resulted in increased numbers of primary follicles with active germinal centres and produced cells primarily lymphoblast/plasmablast in type. The response appeared to involve blast cells of the germinal centres rather than thymus-dependent paracortical areas. Both reticulo-endothelial and lymphoid components exhibited marked cellular necrosis which increased throughout the course of infection. Intense lymphopoiesis was not correlated with lymphocytosis but was associated with lymphopaenia.

Animals↗

PubMed1978

Amicarbalide: a therapeutic agent for anaplasmosis.

When administered subcutaneously in 2 equal daily doses at a total dosage rate of 20 mg/kg, amicarbalide was found to be an effective agent for controlling acute infections of Anaplasma marginale and A. centrale in intact and splenectomized cattle. Attempts to sterilize patent and latent Anaplasma infections, however, were unsuccessful. At total dosage rates of 40 mg/kg and higher, amicarbalide exhibited potent hepato- and nephrotoxic tendencies.

Amidines↗

PubMed1976

Observations on the transmission, immunology, clinical signs and chemotherapy of dourine (Trypanosoma equiperdum infection) in horses, with special reference to cerebro-spinal fluid.

This paper is a record of observations on the transmission and clinical signs of dourine in naturally infected cases of known duration, and of temporal and quantitative aspects of the immune response in blood and cerebro-spinal fluid. Included in the record are observations on the presence of Trypanosoma equiperdum parasites in these body fluids and methods for their detection. There is evidence that the occurrence of nervous symptoms and lesions in infected horses is associated with the presence of Trypanosoma equiperdum parasites in cerebro-spinal fluid. The suitability of cerebro-spinal fluid as an environment for the parasite and its relationship with nervous manifestations of the disease are discussed. Observations support the previously reported lesions of peripheral polyneuritis and suggest a possible correltation between the consitstent position of the nervous lesions and the drainage of cerebro-spinal fluid containing the parasite. Chemotherapy with an experimental drug MSbE was used with varying results in 4 horses at different stages of infection.

Anemia↗

PubMed1976

Experimental intraspinal trypanosoma equiperdum infection in a horse.

To establish the ability of Trypanosoma equiperdum to cross the blood-brain-barrier in the horse, a susceptible stallion was infected via the cerebrospinal fluid of the subarachnoid space by lumbosacral puncture. Cerebrospinal fluid with low detectable levels of trypanosomes removed from a dourine-infected mare by lumbosacral puncture was used for infecting the animal. The parasite was detected in blood smears of the recipient 13 days after infection and the subsequent parasitaemia and clinical course of the disease followed that of naturally infected horses.

Animals↗

PubMed1976

The prevalence of dourine in southern Africa.

The geographical distribution of positive dourine cases found on serological testing at Onderstepoort during the period 1954 to 1975 is recorded, showing major foci of infection occurring in the northern Cape Province, northern Orange Free State, western and north-western Transvaal. Positive cases are also recorded from South West Africa, Botswana, Lesotho, Swaziland and Rhodesia.

Africa, Southern↗