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Biomedical subjects

M Sancho

Publications and source records attributed to M Sancho.

At least 55 records · Page 3Linked to original sources
PubMed1993

Electrostatic interactions in gramicidin channels. Three-dielectric model.

A model based on the solution of the electrostatic potential for a geometry of three dielectric regions associated with a gramicidin A channel (GA) is presented. The model includes a cylindrical dielectric layer to represent the peptide backbone and dipole rings to account for dipolar side chains. Image potential and dipolar contributions for different orientations and positions along the channel are analyzed. The conductance of GA and two analogues obtained by substituting the amino acid at position 1 are studied. The numerical simulation reproduces experimental results (Barrett et al. 1986, Biophys J 49, 673-686) and supports the idea that electrostatic dipole-ion interactions are of primary importance in gramicidin channel function.

Amino Acid Sequence↗
PubMed1993

Amplified fragment length polymorphism analysis of the VNTR locus D1S80 in central Spain.

The polymorphism of the D1S80 locus has been analyzed in a population sample of 203 unrelated individuals living in Madrid (central Spain) by PCR and subsequent semi-dry discontinuous polyacrylamide gel electrophoresis (Tris-chloride/Tris-glycine buffer system) followed by silver staining. The electrophoretic system described in this study offers high resolution in the separation of the different D1S80 alleles allowing the detection of microvariability around the allele T22 in the spanish population. Twenty different alleles containing 17-40 repeats of the basic 16 bp unit were distinguished. The alleles T18 and T24 were found to be relatively common in Spain, as in other populations, with frequencies of 0.224 and 0.372, respectively. No evidence of significant deviations from Hardy-Weinberg equilibrium was found in these preliminary population data.

Alleles↗
PubMed1992

[Prolactinoma as atypical tumor of the nasopharynx].

The paper deals with a Prolactinoma case appearing as a swelling of the rhinopharynx, which developed cephalgia related to the nasal blockade as solitary symptom. Recite of the main clinical characteristics, diagnostic process and therapeutics of this condition. The differential diagnosis with other tumors situated in the sellar space or in the rhinopharynx, is also considered.

Administration, Oral↗
PubMed1991

Identification of human esterase D subunits from the homodimeric and heterodimeric forms of five phenotypes by a new two-dimensional isoelectric focusing method.

A new two-dimensional isoelectric focusing method was developed to identify the human esterase D (EsD) subunits from the homodimeric and heterodimeric forms of five EsD phenotypes. EsD polymorphism was also analyzed by one-dimensional isoelectric focusing under reducing and mild denaturing conditions to study the influence of dithiothreitol and low concentrations of urea on the focusing pattern of the EsD dimers.

Alleles↗
PubMed1991

Genetic polymorphism of alpha-2-HS-glycoprotein in a Spanish population.

The genetic polymorphism of alpha-2-HS-glycoprotein (AHSG) was analyzed in 489 unrelated individuals living in Madrid (central Spain), by isoelectric focusing in miniaturized polyacrylamide gels followed by immunoblotting. The allele frequencies were estimated to be 0.7147 and 0.2771 for AHSG*1 and AHSG*2, respectively. In addition to the common alleles, 3 rare variants (AHSG*3, AHSG*10 and AHSG*11) have been found in this study.

Alleles↗
PubMed1991

[Coronary permeability and left ventricular function following thrombolytic therapy].

We study 40 patients, 55 +/- 7 years old with acute myocardial infarction treated early by thrombolytic therapy (20 STK and 20 rt-PA). All patients were angiographically studied in the following conditions: 1) baseline, before initiating therapy. 2) Three hours after treatment. 3) Twenty four hours later. 4) Before discharge. The infarct related artery was patent 24 hours after treatment in 31 patients (78%); five of them were patent before treatment, and we observed an early reperfusion in 20 patients (57%) and late reperfusion in 6 patients (17%). The number of patients with angiographic evidence of intraluminal thrombus decreased progressively through conditions while the grade TIMI of coronary perfusion increased in the absence of reocclusion. Final regional wall motion of infarct related myocardial zones and their degree of recovery were significantly higher in recanalized patients, as compared with non-reperfused patients. Similarly, left ventricular functional recovery was higher in patients with antegrade of collateral flow to the infarct area, as compared with totally occluded patients.

Coronary Angiography↗
PubMed1990

Factors influencing progression of mitral regurgitation after transarterial balloon valvuloplasty for mitral stenosis.

This study analyzes the clinical, echocardiographic and hemodynamic factors affecting progression of mitral regurgitation (MR) after transarterial balloon valvuloplasty in 200 consecutive patients with rheumatic mitral stenosis. After valvuloplasty, the mitral valve area increased in all patients, from 1.03 +/- 0.36 to 2.06 +/- 0.71 cm2 (p less than 0.0001). With regard to the basal stage, the mitral valve was competent in 139 patients and there was mild MR in 61 (grade I in 53, and grade II in 8). Three patients had progression of MR induced by a technical deficiency and they were excluded from analysis. Patients were classified into 2 groups on the basis of the degree of MR before and after valvuloplasty: group A--no progression of MR (n = 167; 85%) when the degree of MR did not change, disappeared after valvuloplasty, or increased from grade 0 to I; group B--progression of MR (n = 30; 15%) when the degree of MR increased to greater than or equal to grade II. Progression of MR was observed more frequently in older patients with presence of chronic atrial fibrillation, larger left atrial size and left ventricular volumes, baseline MR, more severe stenosis and a lower ejection fraction. Multivariate analysis selected age, left ventricular volumes and ejection fraction as independent predictors of progression of MR. All these factors suggest that progression of MR after balloon valvuloplasty could be related to a more advanced degree of disease.

Age Factors↗
PubMed1990

Haptoglobin subtyping by isoelectric focusing in miniaturized polyacrylamide gels rehydrated in presence of 2-mercaptoethanol.

A fast isoelectric focusing method for routine haptoglobin (Hp) subtyping is presented. This method is based on isoelectric focusing, under reducting conditions, of neuraminidase-treated plasma samples by using dry miniaturized (interelectrode distance: 55 mm) polyacrylamide gel, rehydrated in presence of 2-mercaptoethanol and a mixture of pharmalyte carrier ampholytes (pH 4-6.5 and pH 6-8) followed by immunoblotting. The presence of 2-mercaptoethanol in the gel prevented refolding of the Hp alpha and Hp beta chains during focusing, making it possible to obtain a sharp Hp band pattern with a clear separation of the different Hp alpha allelic products (1S, 1F, 2FS, 2SS and 2FF). A population study carried out with 250 unrelated individuals living in Central Spain is also presented.

Acrylic Resins↗
PubMed1990

Characterization of human catalase by isoelectric focusing in presence of urea.

Human catalase from erythrocytes and liver were analyzed by polyacrylamide gel isoelectric focusing in presence and absence of urea using two different pH gradients, namely pH 6-8 and pH 6.7-7.7. In presence of urea, human catalase focused in the pH range 6.75-7.0, slightly anodal to that of hemoglobin A. In narrow pH gradients, human erythrocyte catalase was microheterogeneous. Neuraminidase from different sources and peptide-N-glycosidase F were applied to investigate the presence of sialic acid and/or carbohydrate chains in human catalase. A shift in the focusing pattern of both erythrocyte and liver catalase towards the anode was observed after treatment with one of the commercially available neuroaminidase preparations. This unusual result could be related to a contaminating protease since no effect was observed when the catalases were treated in presence of a serine protease inhibitor. In contrast, bovine liver and Macaca erythrocyte catalase did not display any detectable change in their focusing patterns after treatment with any of the neuraminidase preparations.

Catalase↗
PubMed1990

Balloon valvuloplasty for mitral restenosis after previous surgery: a comparative study.

We studied 203 patients with mitral stenosis treated by transarterial valvuloplasty. Forty two (group A) had undergone closed (n = 30) or open n = 12) surgical commissurotomy 15 +/- 5 years before. The remaining 161 had not undergone previous surgery (group B). There were no significant differences between both groups in terms of age, sex, functional class, left atrial size, two-dimensional anatomic features of the valve, incidence of mild basal mitral regurgitation, or ejection fraction. A comparative analysis of both groups showed no significant differences in terms of changes in the mean gradient, mitral valve area, and incidence of severe postvalvuloplasty mitral regurgitation (9.5% versus 5.5%). Echo-Doppler follow-up studies (11 +/- 7 months) showed persistent gradient relief in either group. We conclude that the immediate and short-term results of balloon valvuloplasty in patients who had undergone previous surgery are similar to those observed in patients who had not had commissurotomy.

Catheterization↗
PubMed1990

GC subtyping and HIV infection in a Spanish population: no evidence of an association between GC subtypes and AIDS.

Group-specific component (GC) subtyping was performed by isoelectric focusing in 318 Spanish drug users at risk for infection or infected by HIV (85 HIV seronegatives, 111 HIV seropositives without symptoms, 89 seropositives with symptoms, 33 AIDS patients) and 187 healthy individuals. There was no significant association between GC subtypes and susceptibility to HIV infection and/or progression to AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[Role of percutaneous valvuloplasty in rheumatic mitral valve stenosis. Córdoba-Las Palmas cooperative study].

This article describes our findings on a prospective and cooperative study (Córdoba-Las Palmas) in 203 patients with mitral stenosis who underwent balloon valvuloplasty using a retrograde transarterial technique. We analyzed the immediate and mid-term results, and studied the factors determining an optimal result and those related to the new appearance or worsening of mitral incompetence after the procedure. On the other hand, we analyzed the results of mitral valvuloplasty in patients with previous mitral surgery, mild mitral stenosis and patients dilated while having an acute pulmonary edema. We observed a marked decrease in mean mitral gradient (17 +/- 7 to 6 +/- 3 mmHg; p less than 0.001) as well as a significant increase in mitral valve area (1.02 +/- 0.4 to 2.04 +/- 0.7 cm2; p less than 0.001). Echo-Doppler follow-up did not show significant changes in the residual mitral valve gradient. Multivariate analysis selected, as independent predictors of an optimal result, the presence of a pliable valve and the absence of basal mitral regurgitation. On the other hand, the presence of a lower ejection fraction, an older age and a higher baseline left ventricular endiastolic volume were independent factors determining progression of mitral regurgitation. In patients with previous mitral surgery, the clinical, echo and hemodynamic profiles, as well as the immediate results, were similar to those observed in patients with unoperated mitral stenosis. In the subgroup of mild mitral stenosis, we observed and optimal result in all cases, without major complications. Mitral valvuloplasty was dramatically effective in 8 patients treated during acute pulmonary edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Infarct size determination using enzymatic methods in patients with early coronary recanalization].

To evaluate the usefulness of the infarct size determined by serial creatine kinase (CPK) measurements in patients with early reperfusion, we have studied 189 patients meaning in age 59.2 +/- 8.6 years, with acute myocardial infarction treated with streptokinase (STK); 81 of them by intracoronary route (group A), and 108 by intravenous administration (group B). In the group A we performed serial angiographic studies in the following conditions: baseline, immediately after STK infusion and before hospital discharge. In group B we performed only one angiographic control 5 +/- 3 days after. In patients with reperfusion, the parameters of left ventricular function correlated with cumulative creatine kinase release (MAX-CPKr) by linear regression in both groups. We observed a tendency to closer correlations in patients with left anterior descending or circumflex artery as the infarct related artery, in patients without previous infarction and in those who did not receive electrical shock for ventricular arrhythmias. In patients with unsuccessful reperfusion (n = 11), we also obtain a significant correlation (r = 0.72) between ejection fraction and MAX-CPKr. The slope of the regression line (b = 7.7 X 10(-5) was steeper (p less than 0.05) than that observed in recanalized patients, who were evaluated within the first 3 days (b = 2.2 X 10(-5), after 8 +/- 5 days (b = 2.7 X 10(-5), or before discharge, at 22 +/- 9 days (b = 2.6 X 10(-5).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Abrupt homeostatic responses to transient intracardiac occlusion during balloon valvuloplasty.

The present study analyzes the hemodynamics of intracardiac occlusive periods during balloon mitral or aortic valvuloplasty and compares them with immediate plasma levels of atrial natriuretic factor (ANF), vasopressin and renin activity. Forty-nine patients were studied; 33 of them had mitral stenosis and 16 had aortic stenosis. The mean age was 52 +/- 17 years. During dilations pressures were monitored from the ascending aorta and left atrium. Plasma levels of ANF, vasopressin and renin were serially determined at baseline, after diagnostic procedures, within 15 to 30 seconds after the first 2 occlusive dilations, and 1 and 7 hours later. There were no significant changes in plasma renin throughout the study stages. ANF and vasopressin significantly increased after the dilations. These hormonal changes were related to the significant hemodynamic changes observed during intracardiac occlusion. The left atrial pressure correlated directly and significantly (r = 0.54, p less than 0.001) with plasma ANF levels throughout the conditions. On the other hand, the plasma vasopressin also correlated (r = 0.76, p less than 0.001) with systemic pressure in an exponential fashion. These findings show that abrupt releases of ANF and vasopressin occur immediately after intracardiac occlusive periods as a response to the acute and transient hemodynamic changes observed.

Adolescent↗
PubMed1989

Angiographic follow-up after balloon angioplasty for coarctation of the aorta.

Balloon angioplasty for coarctation of the aorta was performed in 45 patients; 17 (Group 1) were infants (mean age 34 +/- 43 days). This study focuses on the remaining 28 patients (Group 2), children and adults ranging in age from 2 to 31 years (mean 13 +/- 8). Two patients had had previous surgery for coarctation; in the remaining 26 the coarctation had not been surgically treated. Twenty patients (71%) had a discrete type of coarctation; the remaining eight had a diffuse or eccentric stenosis. Angiographic studies of the aorta were performed before and immediately after angioplasty in all 28 patients; 16 (57%) of them also underwent angiographic reevaluation 10 +/- 2 months later. The pressure gradient decreased immediately after angioplasty and was unchanged at follow-up. Residual gradient at follow-up ranged from 0 to 40 mm Hg (mean 11 +/- 13). Patients with a discrete type of coarctation had a lesser residual gradient than did patients with other anatomic types of coarctation. Angiographically, the stenosis also decreased after angioplasty (68 +/- 10% versus 24 +/- 17%; p less than 0.01); a new small, but significant decrease was observed at follow-up (9 +/- 18%; p less than 0.05). A quantitative analysis of the aorta at different levels revealed no significant changes proximal and distal to the coarctation segment; however, at the level of coarctation, a significant (p less than 0.01) and homogeneous increment was observed after dilation that was unchanged at follow-up. One (6%) of 16 reevaluated patients had a clear aneurysm at the site of dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Chronic intoxication by heroin; histopathological effects on seminiferous tubules.

Seminiferous tubules from heroin abusers and from rats chronically intoxicated by heroin samples presented a striking reduction in the thickness of the germinal epithelium. Light and electron microscopical studies showed a considerable increase of lipids and phagosomes in Sertoli cells, disorganization of their junction complexes, detachment of immature germ cells which appeared free in the tubular lumen, and formation of giant multinucleate spermatids. These alterations point out that Sertoli cells could be the target element for the toxic effect of heroin samples on the seminiferous epithelium.

Adult↗