Search PubMed⌕ Search

Biomedical subjects

D Mastrangelo

Publications and source records attributed to D Mastrangelo.

31 records · Page 2Linked to original sources
PubMed1983

Postjunctional localization of substance P receptors on the rat portal vein.

A dose-dependent contractile effect of substance P (SP) on the isolated, everted rat portal vein was competitively inhibited by two selective SP antagonists (pro2, phe7, trp9)-SP and (pro4, trp7,9)-SP 4-11. Phentolamine, atropine, methysergide, mepyramine, cimetidine, Sar1, Ile8-angiotensin II, Leu8, des-Arg9-bradykinin and indomethacin did not block the action of SP. However, some of these antagonists differentially reduced SP responses, but such inhibitory effects were shown to be nonspecific. The results suggest that the SP-induced contractions of the rat portal vein were directly mediated by specific receptors localized on the smooth muscle cells. In addition, the response to SP appeared to be independent of prostaglandin biosynthesis.

Adrenergic alpha-Antagonists↗
PubMed1983

[Angiographic diagnosis of mitral valve prolapse: errors and limitations].

In order to assess the reliability of some recently proposed methods for angiographic diagnosis and quantification of mitral valve prolapse (MVP), the left ventricular silhouettes obtained by cineangiography in 48 patients with typical auscultatory and M-mode MVP findings were examined. The following methods were tested in 40 angiographic studies that were found to be of good technical quality: method of Farry et al. (1975), of Smith et al. (1978), of Engel et al. (1978), of Spindola-Franco et al. (1979). In 23 cases a two-dimensional echocardiographic study was also performed and Engel's angiographic criteria were utilized to quantify the MVP. The angiographic and echocardiographic data were correlated in 13 cases in which it was possible to obtain both good quality echocardiographic and adequate angiographic (end-systolic identification of the two mitral valve commissures) studies. The following conclusions can be drawn: a correct angiographic quantification of the extent of bulging requires both end-diastolic and end-systolic identification of both anterolateral and posteromedial commissures; in spite of the good quality of the angiographic studies a correct end-systolic identification of the two commissures is obtainable in less than 50% of cases, which obviously restricts considerably the applicability of any objective method; among the tested angiographic methods only the Engel's method (evaluation of the distance between the plane of the mitral valve and the most protruding point of the prolapsed leaflets) showed a satisfactory diagnostic sensitivity (75% in RAO projection, 89.5% LL projection, 100% utilizing both projections); angiography is not suitable for a quantitative classification of the MVP in mild, moderate and severe forms; such a possibility, on the contrary, seems to be offered by two-dimensional echocardiography provided that Engel's angiographic are adopted.

Adolescent↗
PubMed1978

Electrophysiological properties of intravenous metoprolol in man.

Electrophysiological changes produced by intravenous (0.1 mg/kg) metoprolol, a new selective beta 1-blocking agent devoid of intrinsic activity, were studied in 16 subjects with estimated normal impulse formation and conduction. The most important effects were sinus bradycardia, mild increase of sinoatrial conduction time, depression of intranodal conduction, and prolongation of AV node refractory periods. Sinus node recovery time and atrial refractory periods were unmodified. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle-branches, were unchanged. These effects are compared with those observed after intravenous propranolol, pindolol, and oxprenolol.

Adult↗
PubMedDate not supplied

The polymerase chain reaction (PCR) in the routine genetic characterization of retinoblastoma: a tool for the clinical laboratory.

The Polymerase Chain Reaction (PCR) is a highly innovative technique which allows for the generation of large amounts of DNA starting from minute quantities obtained from the blood or tissue of a patient. With the increasing knowledge concerning the structure of the human genome and the potential to amplify specific segments of DNA by the PCR technique, the molecular genetic characterization of many ocular disorders has been greatly facilitated. This is particularly true of retinoblastoma (RB) where the causative gene, RB1, gene has been identified and characterized. Using PCR technique, specific sequences of the RB1 gene can be amplified and analyzed to precisely define the genetic mutation in an affected individual. In addition, this technique can also be applied in order to characterize the genetic defect within the tumor itself. In this report we illustrate the use of the PCR technique in the genetic characterization of the RB1 gene and its application to the study of RB. These techniques are applicable even in a small clinical laboratory and can be extended to a number of ophthalmic disorders.

Chromosome Mapping↗
PubMedDate not supplied

Binding of gold-protein ligand complexes to neurokinin receptors. visualization with the electron microscope on pig coronary artery and rat portal vein.

Active neurokinin (NK) receptors were visualized with 5-nm colloidal gold-protein-substance P (GPSP) and -senktide (GPSenk) complexes on vascular tissues. Electron micrographs of pig coronary strips incubated with GPSP showed gold particles either bound to the plasmalemma or inside intracytoplasmic vesicles of endothelial cells. Preincubation with SP or the NK1 receptor antagonist L-703606 prevented GPSP marking. No gold particles were seen after incubation with GPSenk. On coronary strips in vitro, which had been precontracted with U46619, GPSP induced relaxations similar to those produced by equimolar concentrations of SP, both relaxations being inhibited by L-703606. Analogous to senktide, GPSenk was totally inactive on arterial strips. Incubation of rat portal veins with GPSenk showed gold particles bound to the plasmalemma or inside intracytoplasmic vesicles of smooth muscle cells. Preincubation with senktide or the NK3 receptor antagonist R-820 prevented GPSenk marking. On portal veins in vitro GPSenk induced contractions similar to those induced by equimolar concentrations of senktide or NKB; these effects were inhibited by R-820. Our results show that colloidal gold-protein complexes present biological activity and selectivity similar to those of their respective native ligand and detect the presence of active receptors; in addition, they suggest the presence of NK-receptor-mediated endocytosis in endothelial cells of coronary artery and in smooth muscle cells of the portal vein.

Animals↗
PubMedDate not supplied

Metachronous tumor development in unilateral retinoblastoma.

PURPOSE: A series of 205 retinoblastoma (RB) patients referred to the Department of Ophthalmology at the University of Siena (Italy) was evaluated in order to assess the proportion of unilateral cases later developing tumors in the companion eye ("metachronous" bilateral retinobastoma) (MBRB). METHODS: The total number of unilaterally affected patients developing tumors in the fellow eye was recorded and the risk factors assessed for the development of asynchronous bilateral retinoblastoma, i.e., family history, tumor multifocality and early age at diagnosis. RESULTS: Only two out of 133 (1.5%) unilateral retinoblastoma patients in our series could be considered affected by MBRB. CONCLUSIONS: The incidence of MBRB in our series was negligible (1.5% of all unilateral cases) compared to other reports. None of the reported risk factors for the development of tumors in the fellow eye was relevant in the present series. Although close follow-up of some unilateral cases is still recommended, thorough examination of the fellow eye, to search for lesions in the peripheral retina, is essential in all cases of unilateral RB. MBRB may be a distinctive clinical entity with specific clinical, genetic and prognostic features. However, all these aspects need to be better investigated in larger series.

Follow-Up Studies↗
PubMedDate not supplied

Phthisis bulbi and buphthalmos as presenting signs of retinoblastoma: a report of two cases and literature review.

PURPOSE: To report two cases of bilateral retinoblastoma (RB) with unusual presentations. METHODS: The medical records of 321 patients from the Retinoblastoma Referral Center in Siena were reviewed. A total of 111 patients had bilateral RB, 2 of them presenting with phthisis bulbi and buphthalmos. Both patients underwent bilateral enucleation. Clinical features, imaging studies, and histopathology were reviewed. RESULTS: These 2 cases represent 0.62% (2/321) in our series. Histopathology did not reveal viable tumor cells in the phthisical eyes; in both buphthalmic eyes the tumor was active, infiltrating the choroid and optic nerve. CONCLUSIONS: Phthisis bulbi and buphthalmos are unusual presenting signs of RB. This very rare combination of these two signs in different eyes of the same patient is probably due to a delay in diagnosis.

Child, Preschool↗
PubMedDate not supplied

Everted portal vein: a sensitive model for studies of vasoactive compounds.

Three preparations of the rat hepatic portal vein, everted, noneverted, and longitudinal strip, were examined for their responsiveness to noradrenaline (NA), substance P (SP), and eledoisin (ED). The longitudinal strips and the everted veins exhibited similar sensitivities to these compounds, whereas the noneverted vein was two to four times less sensitive. The time course to generation of a maximal response was markedly slower for the noneverted vein. The poor reactivity of the noneverted vein is attributed to a reduced accessibility of the compounds to receptor sites. The myogenic responses of the longitudinal strips to NA and ED but not SP were characterized by a tonic-type contracture, whereas everted and noneverted preparations responded to the peptides, at low and intermediate concentrations, with large-amplitude and long-duration contractions. The everted vein is presented as a useful preparation for evaluation of drug-receptor interactions.

Animals↗