Protective effect of nicotinamide against nephropathy in diabetic rats

Nicotinamide was given for 6 months to rats with streptozotocin induced diabetes. Presence of glomerular depositions (mesangial distribution) of IgG was evaluated with immunofluorescence technique. The immunofluorescence staining of the nicotinamide-treated diabetic rats was significantly less pronounced than that of the untreated diabetic rats. Normal age matched controls showed no such staining. The results indicate that nicotinamide retarded the development of the diabetic nephropathy. The findings might be explained by a normalizing effect of nicotinamide on a disturbed tryptophan and/or nicotinamide adenine dinucleotide metabolism. A metabolic hypothesis is formulated, which is consistent with the "glucose overutilization" theory.

Synthesis of a Combined Fragment of Interferon, AcHuIFN αA(30-43)-(123-137)-NH2. Interferon May not be a Sychnological Peptide

AeHuIFN αA(30-43)-( 123-137)-NH2, Ac-Leu-Lys-Asp-Arg-His-Asp-Phe-Gly-Phe-Pro-Gln-Glu-Glu-Phe-Phe-Gln-Arg-Ile-Thr-Leu-Tyr-Leu-Lys-Glu-Lys-Lys-Tyr-Ser-Pro-NH2 was synthesized toward encompassing the “active site” of the interferons. The design of this 29-amino acid peptide was based on considerations of homology between the different interferons and on combining two regions of interferons, and on known and predicted structural features. The peptide was characterized by amino acid analysis, thin layer chromatography in several systems, and by HPLC. As tested, the peptide neither showed antiviral activity nor blocked antiviral activity of interferon, indicating that the active site was not encompassed or that interferon may not be a sychnological peptide.

The prophylactic effect of dipyridamole on the size of myocardial infarction following coronary artery occlusion

Experimental myocardial infarction was induced in adult female Sprague-Dawley rats by ligation of the left coronary artery. During four weeks preceding the operation the animals were given dipyridamole (3 mg/kg initial body weight) i.p. twice a day 5 days per week. Control animals were given saline. Ten days after the operation the rats were killed and the hearts serially sectioned and stained. The volumes of necrotic and non-necrotic myocardial tissue were determined by morphometry on the histological sections. In the dipyridamole-treated animals the volume of non-necrotic myocardium was larger and the necrotic tissue volume smaller than in the control animals.

The effect of increased cardiac pressure load and volume load on the size of myocardial infarction following coronary artery occlusion

The size of the myocardial infarction following standardized coronary artery occlusion was studied in rats with myocardial hypertrophy due to increased pressure load (aortic stenosis) and increased volume load (swimming exercise). The infarction was significantly smaller in the latter than in the former group. In normal control rats the infarction was larger than in the swimming-exercised rats and smaller than in the rats with aortic stenosis, but these differences were not statistically significant. The observations support the idea that the myocardial capillary neoformation previously shown to be induced by physical exercise may limit the infarction following coronary artery occlusion, whereas the absence of such a capillary reaction in pressure-induced cardiac hypertrophy renders the myocardium more vulnerable, to damage by a coronary occlusion. The size and distribution of the infarction was highly variable as was the configuration of the infarction in the individual heart. For an accurate determination of the size of the infarction, serial sectioning of the whole heart is necessary, with a distance between the sections examined not exceeding 0.5 mm.

The effect of antifibrinolysis on renal stone formation

The influence of decreased urinary fibrinolysis on renal stone formation was studied in rats fed on a calculus producing diet. The alteration in the isolated glomerular fibrinolytic activity indicating the amount of urokinase produced has also been investigated using a histochemical fibrin slide technique. The glomerular fibrinolytic activity was significantly enhanced by both tranexamic acid and the dietary treatment. The induced antifibrinolysis resulted in a significantly higher incidence of grossly visible calculi in the renal pelvis and in calcified deposits along the cortico-medullary border of the kidney. The results support the concept that a decline in urinary fibrinolytic activity can lead to the formation of renal stones.

Capillary increase in the skeletal muscle of trained young and adult rats

1. Capillaries in skeletal muscle were studied before and after physical training by prolonged swimming, in young and adult rats. 2. The mean area of striated muscle fibres was unchanged in both young and adult rats after training. 3. Training increased the capillary vasculature of skeletal muscle in both young and adult rats, but proportionally less in the adults.

Long-term results after repair of coarctation of the aorta by patch grafting

Six patients who had been operated upon for coarctation of the aorta with patch grafting between 1958 and 1960 were followed for a minimum of 17 years. One of these patients received an aortic homograft patch for an abdominal coarctation and was in excellent health 21 years later. An aortogram showed no aneurysm formation. One other patient was reoperated upon 1 month after the primary operation because of a pseudoaneurysm. The remaining four patients received either a Dacron graft (three patients) or an Orlon graft (one patient), and they all developed an aneurysm in the aortic wall opposite the patch graft. Three of these patients successfully reoperated upon, but the fourth patient died 17 years after patch grafting because of rupture of the aneurysm. Microscopy (in three patients) showed varying degrees of degenerative changes in the aortic wall opposite the patch. There was no evidence of infection or foreign body reaction in these parts of the aortic walls. The reason aneurysms develop after patch grafting probably is that part of the circumference is replaced by a material with tensile characteristics differing from those of the aorta itself. Repair of aortic coarctations with synthetic patches therefore cannot be recommended.

The proliferative activity of myocardial capillary wall cells in variously aged swimming-exercised rats

Cellular proliferation was studied by incorporation of 3H-thymidine in the hearts of young, adult and old swimming-exercised rats. The proliferative activity was measured by scintillation counting. The swimming exercise induced a significant proliferation of capillary wall cells in the younger age groups, suggesting a neoformation of myocardial capillaries in these rats, whereas no cell proliferation was recorded in the old rats.

Proliferative activity of myocardial capillary wall cells in dipyridamole--treated rats

The hearts of rats treated with dipyridamole were studied by light microscope autoradiography and measurement of tissue radioactivity after intravenous injection of 3H-thymidine. Total tissue radioactivity was significantly increased in the hearts of the dipyridamole-treated animals. Only capillary wall cells were labelled in the autoradiograms. The observations indicate a proliferation of capillary wall cells, suggesting a neoformation of myocardial capillaries during dipyridamole treatment.

The reaction of the vascular pattern of the hypertrophied myocardium to increased cardiac volume load. A microangiographical study

Myocardial stereo-microangiography was performed on 30 rats after swimming exercise for one or two periods with and without a previous operation for production of aortic stenosis. In 8 rats with aortic stenosis no swimming exercise followed, and 10 more rats served as normal controls. Swimming exercise resulted in a higher degree of cardiac hypertrophy than aortic stenosis. Both types of cardiac hypertrophy resulted in vascular adaptive reactions in the myocardium. The adaptive reaction to swimming exercise was found to be persistent, at least to some extent, and to be of use if the exercise was resumed. The adaptive alterations in aortic stenosis were further modified by a superimposed period of exercise, although the nutritive capillary vasculature only showed a slight and focal increase in density.

The myocardial capillary vasculature in repeated physical exercise. An experimental investigation in the rat

The neoformation of myocardial blood capillaries was investigated on cardiac autoradiograms from 3H-thymidine injected rats that had been swimming-exercised for two weeks, rats that had been resting for three months following the exercise, and rats in which the rest had been followed by a second two-weeks period of exercise. The initial period of exercise induced a signficant capillary neoformation in the hearts. The newly-formed vasculature was found of functional significance still at the end of the resting period and available for the increased demands on the myocardial vasculature when the exercise was resumed.

Capillary proliferative activity in myocardium and skeletal muscle of exercised rats

The capillary proliferative activity in heart and skeletal muscle was studied by autoradiography after in vivo injections of [3H]thymidine in swimming exercised rats. Swimming exercise led to hypertrophy of the myocardium and the muscle fibers of the fore- and hindlimbs. When compared with normal controls a highly significant increase in nuclear incorporation of [3H]thymidine was found in the cells of the myocardial capillary walls. No increased incorporation of [3H]thymidine was found in capillary wall cells of fore- and hindlimb muscles. The findings confirm previous observations of a significant neoformation of myocardial capillary blood vessels in swimming-induced cardiac hypertrophy, whereas any capillary neoformation in the hypertrophying skeletal muscles of this experimental model is insignificant.

The myocardial capillary vasculature in exercising animals with increased cardiac pressure load

The myocardial capillary reaction was studied in normal rats subjected to swimming exercise and in rats in which aortic stenosis had been produced at various time intervals before the swimming exercise was commenced. The data obtained indicated that neoformation of myocardial capillaries during swimming exercise occurred only in rats without aortic stenosis. It is concluded that a heart subjected to an increased pressure load is less able to respond to a superimposed volume load by an increase in its capillary supply than is a normal heart.

The effect of angiotensin infusion, sodium loading and sodium restriction on the renal and cardiac adrenergic nerves

The renal and cardiac adrenergic nerve patterns in rats infused with large and small amounts of angiotensin and in rats given NaCl plus DOCA, NaCl alone, and salt-free diets were examined by the histochemical fluorescence method. Infusion of small amounts of angiotensin led to a persistent blood pressure elevation whereas infusion of large amounts of angiotensin resulted in a transient rise in blood pressure, probably due to the development of tachyphylaxis. Nerve patterns were found to be normal in angiotensin-infused rats and in rats given NaCl. In rats given NaCl plus DOCA and in rats subjected to salt restriction, a partial or complete disappearance of the transmitter of the adrenergic nerve terminals were recorded. The findings suggest that angiotensin in itself is incapable of inducing visible alterations in the transmitter content of the terminals. The findings agree with the view that angiotensin potentiates a norepinephrine depletion of the terminals during sympathetic activity, since it can be assumed that increased plasma angiotensin levels as well as various degrees of increased sympathetic tonus were present in the rats subjected to salt restriction. The similar effect on the nerve terminals produced by the combined NaCl and DOCA administration is consistent with earlier reports of an increased turnover of norepinephrine in animals thus treated.