Role of circulating immune complexes and platelet aggregation in the development of experimentally induced atherosclerosis in monkeys with normal intact vas deferens and following vasectomy.

The study was undertaken in normal and vasectomized monkeys to elucidate the relationship of circulating immune complexes and platelet aggregability with experimental aortic and coronary atherosclerosis. Four groups of animals, viz. sham-vasectomized stock diet fed, vasectomized stock diet fed, sham-vasectomized atherogenic diet fed, were studied for a period of 1 year. An increased incidence of atherosclerosis was noted with high levels of circulating immune complexes in vasectomized monkeys. Platelets obtained from atherogenic diet fed monkeys had a clear tendency of increased aggregation and agglutination in the presence of ADP, epinephrine and ristocetin respectively. Vasectomy produced a significant enhancement in platelet aggregation response with ADP and epinephrine in atherogenic diet fed animals. The aortic and coronary atherosclerosis was also significantly increased in atherogenic diet fed groups both with and without vasectomy.

Catecholamine-induced experimental cardiomyopathy--a histopathological, histochemical and ultrastructural study.

An experimental model of myocardiopathy was induced in rhesus monkeys following noradrenaline (NA) infusion (20 ug/kg body wt/minute), for a period of 2 hours daily for three consecutive days. The animals were sacrificed after two hours (acute phase), forty-eight hours (sub-acute phase) and twenty-one days (chronic phase). Focal depletion of succinic dehydrogenase, increase in adenosine triphosphatase, acid phosphatase and appearance of large fat droplets in myocardial muscle was noted in the acute phase. Histopathological examination revealed focal edema, opacity and fuchsinorrhagia of the muscle fibres distributed in both the ventricles. Myofibrillar degeneration, myocytolysis and vacuolization with aggregation of lymphomononuclear cells were the significant features in the acute phase. During sub-acute and chronic phases, these features became less prominent and reparative changes with proliferation of fibroblasts became more marked. By the twenty-first day, irregular, focal scars replaced the necrosed myocardium. Ultrastructurally, heart muscle showed myofibrillar disorganisation, distortion of Z and A bands, dilatation of sarcoplasmic reticulum and swelling and rupture of mitochondria. Altered membrane permeability was evidenced by the presence of reaction products of horseradish peroxidase within the cardiac cells. In the reparative phase, however, myocytolytic changes regressed and collagen deposition was the prominent feature. This experimental study has several histological features simulating human cases of myocardial infarction without coronary occlusion.

Renal involvement in Mycobacterium leprae infected mice. Histopathological, bacteriological and immunofluorescence study.

Swiss albino mice were inoculated in the footpads with Mycobacterium leprae obtained from untreated lepromatous patient. The kidneys obtained from the animals sacrificed during different periods were processed for histopathology, presence of AFB and immunofluorescence studies. Renal lesions, AFB and immune complex deposits were seen in the infected animals. Such findings have not been studied in great detail in experimental leprosy earlier.

Primary dapsone resistance in leprosy.

20 carefully selected untreated patients of bacilliferous leprosy were investigated for primary dapsone resistance by foot pad inoculation. Mice were fed on 0.001 g% and 0.01 g% of dapsone during the period of study. Mice in the control group were given normal rodent feed only. Animals were sacrificed from 6 month onwards at 6 week intervals upto 9 months. In two animals the growth of M. leprae was not inhibited by 0.001 g% concentration of dapsone in diet, but was completely inhibited by 0.01 g% of dapsone.

Influence of levamisole on lymphocytes and M. leprae in mice.

Normal uninfected (N) and M. leprae infected mice (NI) were given levamisole in the dose of 2.5 mg/kg body weight. The animals were observed over a period of nine months for bacillary load, T and B cell counts and blast transformation with PHA. Significant increase in B cell counts was observed in the levamisole treated normal (NL) compared to normal control (N) group. T cell counts and blast transformation, however, remained unaffected. However, T-cell counts and blast transformation improved significantly in the infected and levamisole treated (NIL) as compared to the infected group (NI) not given levamisole. Bacillary loads remained unaltered in both, the infected (NI) and levamisole treated (NIL) group.

Trophic changes and extensive dissemination in normal mice infected with human Mycobacterium leprae.

Closely bred Swiss albino normal mice (Lecca Strain) were inoculated in the footpad with M. leprae, at room temperature. The animals were harvested at 3, 6 and 9 months post inoculation, and bacillary counts were made. Trophic changes were observed in the tail-tips, ears, footpads and forepaws 12-14 months post inoculation in a group which was allowed to survive. The histopathological changes and bacillary infiltration was found in many tissues/organs. The possibility of studying this normal strain of mice as an experimental model for human leprosy has been discussed.

Aortal collagen polymorphism in monkey and man.

Aortal collagen typing in monkey and man showed the presence of types Ι, III and V in human aorta and types I and III in monkey aorta. Type III collagen was found to be a predominate type in both species. The molecular weight of type III collagen was similar in these species while type I collagen was different. Both monkey and human collagen types I and III were found to be immunogenic. Type I collagen was significantly increased while type III was decreased in human atherosclerotic plaque. Collagen typing in fatty streak remained unaltered.

Comparative study of fatty acid composition in human and monkey aorta.

The fatty acid composition of thoracic and abdominal aortic intima and media of normal human subjects and rhesus monkeys has been studied. Significantly higher values of unsaturated fatty acids as compared to saturated fatty acids have been noted in the intima of monkey as compared to man. The fatty acid profile of the aortic wall in these two species has provided a probable biochemical basis for the lesser incidence of atherosclerosis in macaques.