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Biomedical subjects

W B Martin

Publications and source records attributed to W B Martin.

16 recordsLinked to original sources

Role of CD4+ (helper) T cells in the pathogenesis of murine cytomegalovirus myocarditis.

Murine cytomegalovirus causes diffuse myocardial lesions in immunologically intact young adult male BALB/cBy mice. The cardiac changes develop in and around the small penetrating blood vessels of the heart where perivascular and interstitial infiltrates of macrophages and lymphocytes accumulate. Focal lesions of the coronary vessels and the endocardium also appear. When infected mice are depleted of CD4+ T lymphocytes, myocardial lesions fail to develop even though virus replication in the heart is enhanced. Contrary wise, when CD4+ cells are adoptively transferred into infected, thymectomized, irradiated, bone marrow-repleted mice, focal perivascular necrotizing lesions of the heart develop. Depletion of CD8+ T lymphocytes fails to influence virus replication and the development of cardiac lesions. Endothelial and endocardial cells appear to be major sites of virus replication in the heart. Delayed hypersensitivity is hypothesized to be the mechanism of cardiac injury in this model system.

Animals

Murine cytomegalovirus myocarditis.

Murine cytomegalovirus infects a variety of organs after inoculation into adult male mice. We have established a model of myocarditis in which focal lesions from adjacent to virus-infected endothelial cells. The development of the myocarditis is mediated by CD4+ helper T cells. The lesions fail to develop when these cells are eliminated from the animal by administration of a specific monoclonal antibody. Alternatively, repletion of thymectomized, irradiated and bone-marrow reconstituted animals with CD4+ cells results in myocarditis. The evidence, although incomplete, suggests that a delayed hypersensitivity response is the pathogenetic mechanism involved.

Animals

Latent infection of cattle with bovid herpesvirus 2.

In a series of experiments, 10 calves were infected by different routes with bovine mammillitis strain of bovid herpesvirus 2 (BHV2). Nine of the calves developed lesions and BHV2 was isolated from 8 calves. At intervals, after clinical recovery, the calves were given a course of corticosteroid by intravenous injection. Subsequently 7 calves developed lesions and from 3 calves BHV2 was reisolated. The shortest interval between initial infection and reisolation of virus was 10 weeks. In one calf virus was recovered on 3 occasions, at intervals of 20, 44 and 74 weeks post-infection. It is probable that BHV2 can occur as a latent infection in calves and that BHV2 should be included among the herpesviruses known to remain latent.

Animals

Reduced mitogenic responses in cultures of lymphocytes from newly calved cows.

The proliferative responses to stimulation with phytohaemagglutinin (PHA) in cultures of lymphocytes from newly calved and non-pregnant cattle were compared. Lymphocyte cultures from newly calved cows were seen to respond less to PHA than cultures from the non-pregnant cows. It is suggested that this depression in responsiveness of lymphocytes in the immediate post-parturient period may be involved in the etiology of disease in cattle during the immediate post-parturient period.

Animals

Regression analysis of the relationship between physical properties and the in vitro inhibition of monoamine oxidase by propynylamines.

Regression analysis of the potency of inhibition of monoamine oxidase by 47 propynylamines revealed that there are three determinants of inhibitory potency: (1) the smallest substituent on the nitrogen must be methyl or hydrogen in order for any activity to be observed; (2) potency is parabolically related to pKa-the optimum pKa is 6.2; and (3) ortho-substituted benzylamine analogs are ten times more potent than predicted on the basis of pKa values. The optimum pKa cannot be explained by differences in fraction ionized but rather in terms of the multistep sequence whereby these compounds inhibit MAO. A very slight positive effect of hydrophobicity on potency was found. The potency of several analogs not included in the original analysis was predicted.

Alkynes

A comparison of the pathogenicity of three strains of bovid herpesvirus 2 in calves.

The isolates of Bovid herpesvirus 2 share common morphological, physical and antigenic features, but differences in their pathogenicity for cattle have been found among the strains. In order to investigate this aspect in more detail a comparative study was made of the skin lesions produced in calves by three strains of the virus: Allerton BA, bovine mammilitis and 69/1L0. The results show that Allerton BA was less pathogenic for calves than the other two strains used in the experiment. This conclusion is supported by the observations that very few inclusion bodies were found in the lesions produced by Alerton BA, and the maximum titre of virus in the lesions was lower than the titres obtained with bovine mammillitis and 69/1L0. Moreover the thickness and diameter of the lesions with Allerton BA were less than those with the other strains. It is speculated that Allerton BA strain, which originated from a buffalo, might behave similarly to bovine mammillitis and 69/1LO following serial passages in cattle.

Animals