Search PubMed⌕ Search

Biomedical subjects

G Rossi

Publications and source records attributed to G Rossi.

At least 541 records · Page 30Linked to original sources
PubMed1990

Regulation of the expression of the low-affinity IgE receptor (Fc epsilon RII) in the human monocyte-like cell line U-937 by phorbol esters and IgE.

The expression of the low-affinity receptor for IgE Fc epsilon RII) in the human monocyte-like U-937 cell line can be upregulated by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and by IgE. TPA induces terminal differentiation of U-937 cells and causes a four- to fivefold increase in the number of Fc epsilon RII. TPA also modulates the expression of several other membrane markers of U-937 cells. IgE alone has a modest effect on the expression of Fc epsilon RII (about a 10% increase), while simultaneous treatment of U-937 cells with TPA and IgE has a cooperative effect, causing an eightfold increase in the number of Fc epsilon RII. Cycloheximide strongly suppresses the expression of Fc epsilon RII, both in TPA-stimulated and unstimulated cells; this effect can be partly reversed by culturing the cells in the presence of IgE. These results suggest that TPA induces the expression of newly synthesized receptors, while IgE causes an accumulation of preformed receptors.

Antigens, CD↗
PubMed1990

A reevaluation of the hemodynamics of pheochromocytoma.

We examined the hemodynamic features of 24 untreated patients with surgically proven pheochromocytoma during steady-state periods and compared them with 24 untreated essential hypertensive patients individually matched for sex, age, body surface area, and arterial blood pressure. We found that, despite having 10-fold higher levels of circulating catecholamines, pheochromocytoma patients have hemodynamic characteristics similar to patients with essential hypertension and that, in individual patients, the ratio of circulating norepinephrine to epinephrine had no relation to the hemodynamic profile. In both groups, increased total peripheral resistance is primarily responsible for maintenance of hypertension. These results suggest that, unlike the acute administration of catecholamines, long-term exposure to high levels of circulating catecholamines does not produce hemodynamic responses characteristic of this group of compounds. This might be due in part to desensitization of the cardiovascular system to catecholamines and might explain the clinical observation that some patients can be completely asymptomatic despite harboring an actively catecholamine-secreting pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1990

Sodium depletion increases calcium-activated left ventricular pressure in the rat.

Left ventricular dP/dt has been reported to be enhanced in the perfused isovolumic paced heart (Langendorff preparation) isolated from sodium-depleted rats. In this study, we tested the hypothesis that this positive inotropic effect is caused by increased responsiveness of the contractile myofilaments to calcium. To address this question, the calcium-left ventricular pressure relation during tetanization of the whole heart at different extracellular calcium concentrations (2.5, 5.0, 7.5, 12.5, and 15.0 mM) was studied in 19 sodium-depleted (low sodium diet plus diuretics) and 18 control (regular sodium intake) Sprague-Dawley normotensive rats. Results showed that the maximum calcium-activated left ventricular pressure (induced by tetanization) was significantly higher in sodium-depleted than in control rats at 12.5 mM calcium concentration (170 +/- 27 [SD] mm Hg in sodium-depleted rats vs. 112 +/- 14 mm Hg in control rats, p = 0.0005). The calcium concentration at which half-maximal left ventricular pressure response was attained, however, was not different between the two groups. We conclude that long-term in vivo sodium depletion increased the maximum calcium-activated left ventricular pressure without altering the sensitivity of the contractile machinery to calcium.

Animals↗
PubMed1990

From the pattern of human vocal muscle fibre innervation to functional remarks.

About 50% of the human vocal muscle fibres possess several endplates. The direct relation between the number of endplates and rate of contraction, which has been postulated in animals, does not apply to the human vocal muscle. However, it may be that this relation is not indispensable to the particular function this muscle is required to perform and undoubtedly justifies a possible pattern of selective muscle contraction, or better still, of a contraction regulated by a particular, independent mechanism. This mechanism is postulated and discussed.

Humans↗
PubMed1990

In vitro vascular reactivity to endothelin: a comparison between young and old normotensive and hypertensive rats.

In this study we have investigated whether the vascular smooth muscle of a large capacitance artery of spontaneously hypertensive rats (SHR) is hyperresponsive to endothelin-1 and whether the arterial responsiveness to endothelin-1 is affected by aging. Isometric contractions of spirally cut aortic strips from SHR of 11, 22, 33 and 44 weeks of age and from age-matched WKY were measured in parallel. The vessels from SHR did not exhibit a greater responsiveness to endothelin-1 than those from WKY. No difference of responsiveness to the peptide was found among the arteries isolated from WKY of different ages. In contrast, a progressive decrease of responsiveness to endothelin-1 with aging was observed in SHR. This finding seems to be specific for endothelin-1, since the responsiveness to norepinephrine was unchanged. The significant decrease of aortic responsiveness in SHR with aging might be due to chronic hypertension and indicate desensitization to endothelin-1. The latter might be related to chronic in vivo hyperproduction of endothelin, either genetically determined or related to the hypertension-induced endothelial damage.

Aging↗
PubMed1990

Characteristics and biological role of steroid hormone receptors in neuroepithelial tumors.

Tissue samples from 57 patients with neuroepithelial tumors (25 glioblastomas, 18 anaplastic astrocytomas, and 14 astrocytomas) were analyzed in order to evaluate the presence of estrogen, progesterone, glucocorticoid, and androgen receptors. Glucocorticoid- and androgen-specific binding proteins were present in 38.6% and 21.6% of the cases, respectively. Only a few tumors showed estrogen or progesterone receptors. A correlation was found between grade of anaplasia, patient's sex and age, and presence of glucocorticoid and androgen receptors. The biological role of these two receptors was investigated in 10 primary cell cultures derived from neuroepithelial tumors. For this purpose, dexamethasone and testosterone were added to culture medium at different concentrations (from 50 to 0.016 micrograms/ml). A significant stimulation of the cell growth was observed in four of five glucocorticoid receptor-positive cultures when dexamethasone in doses ranging from 2 to 0.016 microgram/ml was added to the culture. No modulation of the growth was observed in glucocorticoid receptor-negative cultures at the same doses. Higher dexamethasone doses induced a significant decrease of the growth index independently from the glucocorticoid receptor status. All of the cultures tested for testosterone activity were negative for androgen receptors. This hormone induced an inhibition of the growth index at doses ranging from 50 to 0.4 micrograms/ml. The data suggest that neuroepithelial tumors contain specific glucocorticoid and androgen binding proteins. Glucocorticoid receptors modulate the growth of cultured neuroepithelial tumors in the presence of different concentrations of dexamethasone.

Adult↗
PubMed1990

[Anatomy of lower incisor root canals].

Not to know the endodontic anatomy is one of the reasons of a root canal failure. Numerous researches have demonstrated it. After a revision of the literature, the Authors expose their cases of multiple root canals in mandibular incisors. The 79 extracted teeth are studied by radiographic method in a "natural" projection and in a latero-lateral one. 29% of the examined teeth have multiple root canals. The Authors give some warning and advice to a therapeutic success in endodontic treatment of mandibular incisors.

Dental Pulp Cavity↗
PubMed1990

[High prevalence of obstructive lesions of the extracranial carotid arteries in reno-vascular hypertension].

Ischemic stroke represents a leading cause of death in patients with renovascular hypertension. In the vast majority it is related to obstructive lesions of the extracranial tracts of the carotid arteries. Since no data were previously available on carotid artery lesions in patients (pts) with renovascular hypertension, a prospective case-control study was undertaken to assess the prevalence of carotid artery lesions in renovascular hypertension. Nineteen pts (10 females and 9 males, age: 26-77 yrs) with a diagnosis of renovascular hypertension based on the presence of uni- or bilateral renal artery stenosis and favourable outcome after either percutaneous transluminal renal angioplasty or surgery, and/or renal vein studies, were evaluated. The cause of renal artery stenosis was atherosclerosis in 12 pts and fibrodysplasia in 7. Each pt was matched with a control pt with primary hypertension for sex, race, age, blood pressure levels, smoking habits and serum cholesterol levels. Carotid artery lesions were assessed using a high resolution echo-Doppler (Duplex) system (Biosound 2000, probe 4 cm, 8 mHz). After the matching, the two groups were almost identical in terms of demographic features and risk profile. In the control group the prevalence of carotid artery lesions was similar to that reported in the literature. On the contrary, a highly significant higher prevalence of carotid artery lesions was observed in the pts with renovascular hypertension (92.1 vs 42.1%, respectively; p less than 0.001). Subgroup analysis showed that this difference was found mainly in pts with atherosclerotic renal artery stenoses.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

[Von Hippel syndrome with recurrent pheochromocytoma].

A patient with Von Hippel disease is described. The Von Hippel syndrome is a genetic disease characterized by a retinal angiomatosis and multiple tumors (renal and pancreatic sites are common). The pheochromocytoma is-on the contrary-very uncommon and the association with 2 pheochromocytomas has probably never been reported. In our case, a double pheochromocytoma (the first in 1973, the second in 1986) was present, in conjunction with a thyroid tumor and with an anomalous renal vein (circumaortic ring). The clinical picture was characterized by a severe hypertension and a fourth stage retinopathy. A correct diagnosis was established only 10 years after the clinical exordium. The thyroidectomy and the ablation of both the pheochromocytomas were necessary.

Adrenal Gland Neoplasms↗
PubMed1990

[A critical analysis of the transfusion protocol in lung surgery].

Autotransfusion carried out in 100 patients undergoing chest surgery is discussed. The Authors emphasize the need to determine a protocol in transfusion procedures for thoracic surgery and stress the importance of using haemocomponents in lieu of whole blood, taking into consideration transfusional risks.

Adult↗