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Biomedical subjects

G Tripodi

Publications and source records attributed to G Tripodi.

45 records · Page 3Linked to original sources

Genetic and experimental hypertension in the animal model-similarities and dissimilarities to the development of human hypertension.

In this article, we present the results we have obtained from experimental and genetic models of human essential hypertension, in order to investigate those findings relevant to understanding the time course and the mechanisms underlying the human disease. With experiments on the renal artery constriction in the conscious dog, we have shown that a kidney lesion can produce a form of hypertension not different, in the established phase, from the essential one and that the onset of this form follows a phasic pattern during which the initial stages are crucial for understanding the mechanisms leading to hypertension. We also consider a rat model (MHS) that spontaneously develops a form of hypertension very similar to the human disease. In this model, we have demonstrated by a kidney cross-transplantation experiment and functional studies that the kidney is responsible for the rise in blood pressure and that the organ dysfunction is probably due to a primary abnormality in ion handling of the cell membrane. This cellular alteration, detected both in MHS erythrocytes and in their kidney proximal tubular cells, should be the cause for the higher rate of kidney Na+ reabsorption observed in the MHS. Comparing this animal model with, at least, a subgroup of humans prone to develop hypertension or already hypertensive, it is possible to detect a series of similarities in the kidney function, hormonal pattern, and cellular function of the two species that allows us to argue that the MHS is a suitable model from which to draw conclusions relevant to the pathogenesis of essential hypertension in some humans.

Animals↗

Congenital aneurysm of the left atrium.

Left atrial aneurysm is a rare condition. Only 29 cases have been reported, to our knowledge. We report 1 such case in a 24-year-old man who complained of dyspnea and arrhythmias. Diagnosis was suspected on review of chest roentgenogram and confirmed by echocardiography and cardiac catheterization. Surgical repair was achieved without complications, and preoperative symptoms disappeared completely. According to the literature, these patients are almost always asymptomatic. When present, the most common symptoms are arrhythmias, heart failure, emboli, and chest pain. This lesion is seen mainly in young adults (mean age, 23.5 years). The diagnosis should be confirmed by echocardiography, nuclear imaging, and cardiac catheterization. A review of the literature indicates that surgical repair can be accomplished with low mortality and that arrhythmias usually disappear postoperatively.

Adult↗

Calcium ATPase in erythrocytes of spontaneously hypertensive rats of the Milan strain.

Calcium (Ca)-dependent ATPase activity was determined in erythrocyte membrane ghosts from normal and spontaneously hypertensive rats of the Milan strain in order to detect changes in enzyme activity which had previously been shown in the spontaneously hypertensive rat strain. Activity was similar in control and hypertensive rats in the absence of calmodulin. In contrast, activity in the presence of saturating amounts of calmodulin was significantly lower in the hypertensive rats. At the Vmax (free Ca2+ concentration 10 mumol/l) the decrease was about 30% (70.1 +/- 8.94 versus 49.1 +/- 4.75 nmol of ATP split/mg of ghost proteins per min; P less than 0.05). The affinity of the ATP-dependent Ca2+ pump for Ca2+ (Km about 1 mumol/l) was not altered in the hypertensive rats. It is possible that deficient Ca ATPase activity sustains an increase of intracellular free Ca in cells of hypertensive rats concomitant with the intracellular sodium (Na) decrease typical of this strain.

Animals↗

Unusual cell structures in tumor-like formations of Gracilaria (Rhodophyta).

This paper deals with electron microscopic observations on cultivated plants of the marine red alga Gracilaria verrucosa which developed simple galla; also sea collected material, without galls, had been studied. The galls showed unusual but characteristic cell structured, caterpillar-like bodies, containing rows of fusiform bodies. These were found mostly in the cytoplasm near the plastids, in one case connected with the endoplasmic reticulum, occasionally even inside the nucleus, and are described here, as far as we know, for the first time. It does not seem probably that the caterpillar-like bodies represent mitochondria or bacteria, but the hypothesis that fusiform bodies are related to virus-like structures is discussed. The normal tissues as well as the gall tissue of the laboratory plants contained, besides plastids typical for the red algae, another type of plastids characterized by tubular thylakoids.

Cytoplasmic Granules↗