Effect of selective depletion of fibrinogen on the evolution of cholesterol-induced atherosclerosis in rabbits

Atherosclerosis was produced by induced alimentary hyperlipaemia in four groups of rabbits. Animals of groups II and III received cholesterol feeds daily for 2 months while in groups IV and V this was followed by another 3 months of intermittent feeding. Group I comprised normal control rabbits. Selective fibrinogen depletion was produced in groups III and V with Arvin so as to maintain the plasma fibrinogen around 100 mg/dl over the last 2 months of cholesterol feeding. Serum lipids, blood coagulation and euglobulin clot lysis as well as the post mortem histopathology of aorta, heart, kidneys, liver and lungs did not reveal any significant differences between corresponding groups of hyperlipaemic animals treated with (groups III and V) or without (groups II and IV) Arvin. It appears that fibrinogen or fibrin incorporation does not play a significant role in the pathogenesis of atherosclerotic lesions induced in rabbits by cholesterol feeding.

Three-dimensional reconstruction of jejunal biopsy in tropical sprue

There is a lot of diversity in the observations on jejunal histology between light and discretion microscopy in tropical sprue. In order to compare the light and dissection microscopic appearances, a three-dimensional model of the villous pattern was constructed after a study of 350 serial sections of jejunal biopsy from a patient with tropical sprue. There was considerable variation in the morphological appearance of the villi in different sections. The changes seen varied from mild to partial villous atrophy. Broad synechia and bridge formation between adjoining villi due to fusion was frequently observed. It is postulated that the process of fusion of villi may be partly responsible for the development of features of partial villous atrophy seen in jejunal biopsies in tropical sprue. Normal jejunal pattern reported by some workers in patients with tropical sprue could possibly be due to inadequate sampling of the total biopsy piece.

Serum lipid profiles in patients of myocardial infarction in the Chandigarh area (Northern India)

To study the incidence of hyperlipoproteinaemia in patients with myocardial infarction (MI) in the Chandigarh area, estimations of various lipids have been carried out in 83 patients. A serial study has been carried out in 31 patients. Serum lipoproteins and uric acid were also estimated. Results show an incidence of only 18% hypercholesterolaemia in patients with MI and 15% in normal subjects. Age-wise distribution of hypercholesterolaemia was slightly higher in 41-60 years old patients when compared with other age groups. No other abnormality in lipid profile was observed. Hyperuricaemia was not observed. These results, therefore, differ markedly from those of similar studies published from the western world.

Peripheral vascular deficit in leprosy

There is considerable controversy regarding the frequency and significance of vascular lesions in leprosy. Thirty-five patients of leprosy under 40 years of age, without any local and systemic arterial disease, with normal looking hands and feet, were subjected to brachial arteriography. One patient also had posterior tibial arteriography. Diagnosis of leprosy was confirmed by bacteriologic and histopathologic technics. Biopsy material was studied from the area of radiographic abnormality, similar material was obtained from nine matched control subjects at autopsy. Skin thermometry and reflex vasodilatation were studied in eight cases. Various fractions of serum lipids and cholesterol were estimated in all patients and found to be within normal range. Arteriographic abnormalities such as occlusion, narrowing, tortuosity, dilatation, poststenotic dilatation, irregularity and incomplete filling of the lumen by radio-opaque material, were seen in more than two vessels in 50% of the arteriograms in wrist and palm; digital vessels showed abnormality in 75% to 94% of cases. The ulnar artery was more frequently involved (74%) than the radial (50%). Superficial and deep palmar arches were equally affected. Increased vascularity in hypothenar eminence area was seen in three arteriograms. Marked increase in arcuate vessels was noted in 60% of patients. Some arcuate vessels were serving as collaterals. Histologically, all grades of vessels including capilaries showed changes in nearly half of the patients. Reflex vasodilatation was lost in three patients of dimorphous leprosy, and impaired or absent in three of five patients of lepromatous leprosy. There was no predilection for any form of leprosy to show arterial changes more than others. This study clearly demonstrates that the vascular involvement in leprosy is very frequent and must be playing an important role in causing mutilations and deformities of hands and feet.

Peripheral arteriographic studies in leprosy

There is a considerable controversy regarding the frequency and significance of vascular lesions in leprosy. Twenty-six cases of leprosy below the age of 40 years, without any local or systemic arterial disease and normal looking hands were subjected to brachial arteriography. One patient had posterior tibial arteriography also. The diagnosis of leprosy was confirmed by histology or bacteriological staining techniques. Biopsy material was studied from the involved areas and similar material was obtained from nine matched control subjects at autopsy. Skin thermometry and reflex vasodilatation was studied in eight cases. Arteriographic abnormalities such as occlusion, narrowing, tortuosity, dilatation, irregularity and incomplete filling were seen in more than two vessels in the hand in 50%, and in the digits in 75% of the cases. The ulnar artery was more frequently involved than the radial. Superficial and deep palmar arches were equally affected. Marked increase in arcuate vessels was noticed in nearly three-quarters of the patients, and in some, arcuate vessles were serving as collaterals. Histologically all sizes of vessles, including the capillaries, showed changes in nearly half the cases. Reflex vasodilation was lost in three cases of dimorphous leprosy and impaired or absent in three out of five cases of lepromatous leprosy. There was no predilection for any form of leprosy to show arterial changes more than the other. This study clearly demonstrates that the arterial involvement in leprosy is very frequent and must be playing an important role in causing mutilation and deformities of hands and feet.

Effect on the reproductive functions of female rhesus monkeys of feeding irradiated wheat flour and potato diet

We investigated the effects on reproductive functions of feeding adult rhesus monkeys on a diet of irradiated wheat flour and potato. Wheat flour and potatoes were exposed to 75000 and 10000 rad, respectively, of gamma-irradiation and then fed to the animals. Various parameters of reproductive function were compared with those of animals fed on unirradiated food. These were: external changes in the reproductive organs, menstrual cycle, vaginal cytology, assay of urinary hormones (oestrogens and pregnanediol), and post-mortem histopathological examination of the reproductive organs. At the end of 3 months, the experimental and control animals behaved similarly with regard to their reproductive functions.

Systemic stress in the production of cardiac thrombosis in hypercholesterolaemic rats

An experimental study to elucidate the effects of feeding a high fat diet, hypercholesterolaemia and superadded acute and chronic stress on the production of cardiac thrombosis was carried out in rats. The high fat diet contained 25 percent butter rat providing 45 percent calories from fat which produced significant increase of serum cholesterol and other lipids. Acute stress was induced by two injections of adrenaline on a single day which caused a marked transient alteration of haemodynamics. Chronic stress was of two types, physical and metabolic. The physical stress was induced by repeated exposure of the rats to electric shock or roller drum exercise, while metabolic stress was caused by repeated injection of ACTH. Rats of both acute and chronic stress groups showed variable degree of medial degeneration, hyaline and fibrinoid intimal deposits and calcification in coronary arteries. Cardiac thrombi were seen in 30 percent animals subjected to adrenaline shock. Among the chronic stress procedure 17 percent rats exposed to electric shock and only one rat of the ACTH group developed cardiac thrombosis but no thrombus was detected in those exposed to roller drum exercise. The myocardium showed patchy necrosis with or without calcification, Spontaneous mortality was maximum following acute adrenaline shock (25 %) while electric shock caused mortality in 17 percent animals. The other procedures did not lead to spontaneous mortality. This study highlights the significant role of high fat intake, hypercholesterolaemia and systemic stress in the pathogenesis of acute cardiac thrombosis and myocardial necrosis/infarction.

Serum and aortic lipid profiles in spontaneous and cholesterol-induced atherosclerosis in Rhesus monkeys

Serum lipids and lipoproteins and various lipid fractions in the aorta were compared in spontaneously-occurring and cholesterol-induced atherosclerosis of rhesus monkeys. A group of 30 normal monkeys were also studied. Serum cholesterol, total phospholipid and triglyceride values in spontaneous atherosclerosis were similar to normal, but were significantly elevated in cholesterol-induced atherosclerosis. Fractionation of the major phospholipids in animals with spontaneous atherosclerosis showed increased PC with decreased LPC and SP + LPE, while PE was elevated and SP + LPE diminished in cholesterol-induced atherosclerosis. Beta-lipoproteins were markedly increased in cholesterol-induced atherosclerosis, but remained normal in spontaneous atherosclerosis. Among the aortic lipid, PC and PE were significantly elevated in spontaneous atherosclerosis, but in cholesterol-induced atherosclerosis all the neutral lipids were raised, together with a specific rise of PC and decrease of SP + LPE. These observations tend to indicate that the mechanism of atherosclerosis production in the two states greatly varies.

Packed cells, platelet-rich plasma, and adenosine diphosphate in the production of occlusive vascular changes in lungs of rabbits

An experimental study to simulate the lesions of primary pulmonary hypertension was under-taken in rabbits. Five groups were made, each having six animals and these were given separately packed cells (3 per cent suspension of homologous erythrocytes in physiologic saline), plasma rich in platelets, plasma without platelets, ADP solution, and normal saline injections biweekly for a period of three months. Clinical, electrocardiographic, and histologic examination of the lungs were made. It was noted that animals given packed cells, plasma rich in platelets, and ADP solution developed electrocardiographic changes and histologic lesions in the lungs suggestive of pulmonary hypertension.

In vivo thrombolysis. An experimental model in rhesus monkeys

An experimental model of diffuse thromboembolism in the intrarenal circulation of the rhesus monkey was produced by intra-arterial injection of homogenised, homologous [125-I]fibrin. A sequential study of thromolysis was carried out using the conventional method of determining the thromboembolic index in the arteries of both kidneys together with radioautography and counting of radioactivity in the renal homogenate. Quantitative estimation of radioactivity in the renal homogenate, as well as radioautography of kidney sections provided more accurate and sensititve indices of the thrombolytic process than the conventional thrombembolic index. Studies on blood coagulation and fibrinolysis revealed only mild changes corresponding to the dynamics of thrombolysis in vivo. It was further noted that the thrombolytic mechanism in rhesus monkeys is very active and can clear thromboemboli from the intrarenal arteries within 8 days of their induction

Spontaneously occurring hypertension in wild Rhesus monkeys

In this study naturally occurring hypertension in wild rhesus monkeys has been noted with a frequency of 13 out of 428 monkeys examined. The maximum systolic/diastolic blood pressure was 242/140 mm of Hg. Clinically there was evidence of grade I retinopathy in one case only, otherwise the animals did not manifest any symptom to suggest illness. Biochemical examination revealed normal plasma angiotensin activity but the level of serum sodium was slightly elevated. The serum potassium, blood urea and serum creatinine values were within normal limits. Serum cholesterol was, however, elevated in two cases. All hypertensive animals were sacrificed by exsanguination and a complete autopsy was performed. It revealed left ventricular hypertrophy in almost all cases, patchy myocardial degeneration with fibrosis in 3 animals and advanced renal disease only in 3 cases. It therefore appears that most of these cases of hypertension belonged to the idiopathic group.

Myocardial lesions induced by prolonged alcohol feeding in rhesus monkeys

To elucidate the effects of chronic alcohol ingestion in monkeys a synthetic, adequately balanced, fluid diet providing 40% of total calories from ethanol was gavaged through a stomach tube daily over a period of three months. Clinical, biochemical, radioisotope, and histopathological studies were performed at the beginning and end of the experiment. It was observed that chronic alcohol feeding at this dose level caused maked accumulation of triglycerides, cholesterol, and phospholipids in the serum and the liver. In the heart triglycerides and cholesterol ester were increased. Incorporation studies showed increased synthesis of triglycerides in the heart muscle and liver. Histologically the heart showed fatty change of the myocardium and evidence of focal myocytolysis, atrophy of muscle bundles, and early fibrosis. The liver showed generalized fatty change but no cirrhosis.