PubMed Health⌕ Search

Biomedical subjects

S Masia

Publications and source records attributed to S Masia.

8 recordsLinked to original sources
PubMed1990

Evidence for a direct and non-receptor-mediated action of 5HT2 antagonists on transmembrane cation transport systems.

Changes in transmembrane sodium fluxes have been reported in normotensive and in hypertensive subjects after ketanserin administration. In this study, the effects of the serotonergic system on transmembrane sodium transport mechanisms have been investigated in vitro. In erythrocytes drawn from ten healthy subjects, we studied the effects of serotonin (5HT) on the Na/K pump, Na/K cotransport, Na/Li countertransport, and passive permeability of Na. No significant changes were found. A direct, non-receptor-mediated action of ketanserin was then suspected, and the effects of two concentrations of ketanserin (5 x 10(-8) and 5 x 10(-7) M) were evaluated in erythrocytes from 12 normal volunteers. Both concentrations of ketanserin significantly decreased the activity of the Na/K pump and increased the activity of Na/Li countertransport. Na/K cotransport and passive permeability were not affected. Indirect evidence of the action of ketanserin on sodium transmembrane fluxes came from other experiments. In the red blood cells taken from five normal subjects and incubated for 2 hours in a plasma pool, we evaluated the changes in intracellular sodium concentration induced by the presence of 5HT or ketanserin. A significant decrease in intracellular sodium concentration occurred only with ketanserin. This study indicates that ketanserin has a direct influence on transmembrane sodium fluxes. If this action were also present in other cells, it might contribute to the actions of the drug at vascular, nervous, and renal tubular levels.

Adult↗
PubMed1990

[Ventricular afterload and transmitral Doppler flow profile: effects of the diving test].

The influence of loading conditions on mitral flow velocity profile was studies by pulsed wave Doppler echocardiography in 10 normal subjects during diving test (5 min face exposure to iced water). The cold stimulus increased blood pressure (p less than 0.001), peripheral resistances (p less than 0.001), peak-systolic and end-systolic left ventricular (LV) meridional wall stresses (p less than 0.005). No significant change was found in heart rate. LV end-diastolic volume was unchanged, while LV end-systolic volume increased (p less than 0.005). Consequently, LV fractional shortening decreased (p less than 0.001). Thus, in spite of enhanced LV contractility (assessed by a significant increase in LV end-systolic stress to volume ratio, p less than 0.02) LV pump performance fell, because of prevailing afterload as well as lack of acute recruitment of LV preload reserve (afterload-contractility mismatch). Such an increase in LV afterload was associated with remarkable changes in LV diastolic dynamics: isovolumic relaxation time (IRT) was prolonged (p less than 0.001) and ventricular filling was relatively displaced towards late diastole (peak early to peak atrial velocities ratio, pE/pA: 1.5 +/- 0.3 vs 1.9 +/- 0.3 p less than 0.001; peak atrial filling rate: 326 +/- 47 vs 242 +/- 38 ml/s; p less than 0.001; normalized late diastolic velocity: 0.87 +/- 0.10 vs 0.73 +/- 0.06; p less than 0.01). Also, IRT values significantly correlated with pE/pA values (r = -0.75; p less than 0.001). In conclusion, diving test produced important changes in LV hemodynamics which, in turn, influenced LV relaxation and filling pattern. Our results indicate that operative LV loading conditions should be considered when assessing diastolic function by the analysis of transmitral Doppler flow profile.

Adult↗
PubMed1989

[Intraoperative pancreatic echography].

The US intraoperative diagnostic procedure is useful either for the higher sensitivity rate or for the surgical decision making. The Authors' intraoperative diagnostic experience in pancreatic diseases is reported: 23 exocrine and endocrine neoplasms, 3 chronic pancreatitis and 8 acute pancreatitis cases are discussed.

Humans↗
PubMedDate not supplied

Quantitative neuronal c-fos and c-jun expression in Alzheimer's disease.

Apoptosis, or programmed cell death, has been proposed as a mechanism of neuropathology in Alzheimer's disease (AD). Activation of immediate early genes (IEG) c-jun and c-fos appears to be required for the initiation of apoptosis. Furthermore, the expression of c-jun is induced in cultured neurons that undergo beta-amyloid-mediated apoptosis suggesting a direct role for c-jun in the apoptosis of AD neurons. Using immunohistochemical methods, we calculated the average number of neuronal profiles per unit area expressing c-Jun and c-Fos within hippocampal regions CA1, CA2/3, and CA4 in postmortem brain samples from AD patients and age-matched non-AD patients. There was an increase in c-Jun-positive and c-Fos-positive neuronal profile density in nearly all AD hippocampal regions examined. In cerebellum there was no evidence of apoptosis as determined by using TUNEL technique, and negligible c-Jun labeling.

Aged↗