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Biomedical subjects

A Porta

Publications and source records attributed to A Porta.

86 records · Page 5Linked to original sources
PubMed1992

Preserved para-arteriolar retinal pigment epithelium retinitis pigmentosa.

In two patients, we studied retinitis pigmentosa with preservation of the retinal pigment epithelium adjacent to and under the retinal arterioles (despite panretinal degeneration). Both patients with preserved para-arteriolar retinal pigment epithelium also exhibited a peculiarly strong hyperopia. In addition to previously reported features, these patients also had sheathing of the major vascular arcades, which suggested a vascular involvement in this uncommon form of retinitis pigmentosa.

Adult↗
PubMed1992

Spectral analysis of sympathetic discharge, R-R interval and systolic arterial pressure in decerebrate cats.

In 19 decerebrate and artificially ventilated cats, we analyzed, with a power spectral methodology, the variability simultaneously present in R-R interval and in thoracic preganglionic sympathetic outflow. R-R interval was characterized, as already described in humans and other experimental preparations, by two rhythmic components occurring at a frequency of about 0.1 Hz (low-frequency, LF) and at one corresponding to respiratory rate (high-frequency, HF) which, in these experiments, was set at 0.32 Hz. Two similar rhythmic components were also present in the sympathetic discharge. Arterial pressure changes were produced by aorta or vena cava flow obstruction in order to produce reflex responses in sympathetic activity. Reflex sympathetic excitations induced an increase in the LF component of both R-R interval and sympathetic discharge variabilities, while the HF components were simultaneously reduced. In contrast, reflex sympathetic inhibitions were accompanied by a decrease in LF components of both variability signals, while the HF components were simultaneously increased. A significant and positive correlation was found between changes in impulse activity and the amplitude of LF component of either R-R interval or sympathetic discharge variabilities. These data support the hypothesis that the low-frequency component of R-R variability can be used as a marker of sympathetic modulation.

Animals↗
PubMed1992

[The proton radiotherapy of melanoma of the uvea. The technic, methodology and first clinical observations].

Since June 1991, a Cyclotron unit with a proton beam of 65 MeV has been working at the Institute Antoine Lacassagne in Nice, France. An international cooperative group has been founded to guarantee the thorough exploitation of the facility through complete cooperation. From June 17 to December 20, 1991, 47 patients with uveal melanoma were treated; 4 of them entered the study by means of the Italian team and were treated in cooperation with the Cyclotron staff. Treatment modalities and preliminary observations are described.

Adolescent↗
PubMedDate not supplied

B-50/GAP-43 phosphorylation in hippocampal slices from aged rats: effects of phosphatidylserine administration.

Phosphorylation of the presynaptic protein B-50/GAP-43, a substrate of protein kinase C (PKC), has been implicated in neuronal mechanisms related to learning and memory. We evaluated both basal (5 mM KCl) and stimulated (30 mM KCl) B-50/GAP-43 phosphorylation in 32P-prelabeled hippocampal slices obtained from adult and senescent male Sprague-Dawley rats. The in situ B-50/GAP-43 phosphorylation was assayed by quantitative immunoprecipitation. There was no age-related difference in B-50/GAP-43 basal phosphorylation. However, B-50/GAP-43 phosphorylation in depolarized slices from aged rats was significantly decreased relative to that of adult animals. Aged rats were treated with either tris buffer or sonicated suspension of phosphatidylserine (PS) in tris buffer (15 mg/kg IP for 7 and 17 days). PS did not affect basal and high K(+)-induced B-50/GAP-43 phosphorylation in the 7-day treatment. However, after 17 days, PS restored the K(+)-induced B-50/GAP-43 phosphorylation. It is proposed that repeated PS administrations might be beneficial to the age-induced deterioration of endogenous B-50/GAP-43 phosphorylation by acting on Ca++ homeostatic mechanisms and/or PKC.

Aging↗
PubMedDate not supplied

Characterization of cancer-related disseminated intravascular coagulation in relation to tumor necrosis factor-alpha blood concentrations: possible therapeutic role of pentoxifylline.

AIMS AND BACKGROUND: Preliminary experimental data suggest the involvement of tumor necrosis factor (TNF) in determining endothelial damage related to disseminated intravascular coagulation (DIC). The present study was performed to investigate TNF secretion in DIC occurring in metastatic solid tumor patients and to evaluate the possible therapeutic role of pentoxifylline, which has been proven to have a TNF-lowering activity. METHODS: The study included 20 metastatic solid tumor patients who showed clinical and laboratory signs of DIC. Pentoxifylline was given orally at a dose of 1200 mg/day for 28 days. RESULTS: Abnormally high levels of TNF were found in 13/20 patients, and mean TNF serum levels observed in patients were significantly higher than those seen in a control group of 50 healthy subjects. Fibrinogen plasma concentrations were low in 11 cases. Patients with low fibrinogen values showed significantly higher mean TNF levels than those with normal or elevated concentrations. Pentoxifylline therapy induced a significant decrease in mean TNF concentrations and a significant increase in mean platelet number, which returned to within the normal range in 11/20 patients. An increase in platelets in response to pentoxifylline was more evident in patients with elevated pretreatment TNF values. CONCLUSIONS: Our results suggest the existence of abnormally high blood levels of TNF in cancer-related DIC, mainly in the presence of low fibrinogen values. Moreover, they indicate that pentoxifylline therapy may determine a decrease in TNF levels in DIC patients, an event associated with an increase in platelet number.

Adult↗