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Biomedical subjects

A Pastor

Publications and source records attributed to A Pastor.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effect of cyclosporin on lung diffusing capacity in renal transplant patients.

A prospective lung function study pre- and postrenal transplantation was performed on 21 patients in order to evaluate whether cyclosporin decreased the lung diffusing capacity due to lung toxicity. Initial inclusion criteria were absence of respiratory symptoms and normal findings in both chest X-ray and pulmonary function tests. Participants had to be nonsmokers. We determined spirometry including lung volumes, arterial blood gases, carbon monoxide diffusing capacity by the single breath method (DLCOSB), and rate of CO uptake per unit of lung volume (KCO) before and 3, 6, and 12 months after transplantation. Immunosuppression consisted of prednisone and cyclosporin, maintaining total blood levels between 100 and 250 ng/ml. Spirometric and blood gases data remained within reference levels during the follow-up. Hemoglobin (Hb) pretransplant concentrations remained low, returning to their normal levels post-transplantation. Pretransplant DLCOSB levels were slightly decreased but fell within the therapeutic range after correction for Hb concentration, unlike the mean KCO levels which remained slightly diminished despite their correction. In post-transplant controls, the values obtained for both DLCOSB and KCO were significantly higher at the different post-transplant intervals (P < 0.005) than pretransplantation but only when compared without Hb correction. No significant differences for DLCOSB were found when corrected values were compared, and an improvement in the KCO appeared to be significant at 12 months posttransplantation. Based on these findings, we feel that when serum levels are within the therapeutic range, cyclosporin fails to alter the respiratory function or the pulmonary diffusing capacity of the lung.

Adult↗
PubMed1994

In-vitro postantibiotic effect of sparfloxacin and ciprofloxacin against Pseudomonas aeruginosa and Enterococcus faecalis.

The effect of concentration and exposure time on the postantibiotic effect (PAE) of sparfloxacin and ciprofloxacin against Pseudomonas aeruginosa Psa-1 and Enterococcus faecalis SD-63 was evaluated by the colony counting method using centrifugation to remove the antibiotic. The microorganisms were exposed for 15, 30 and 60 min to drug concentrations ranging from 1 x MIC to 31 x MIC. The PAE was calculated as the difference in time required by test and control cultures to increase 1 log10 after the drug was removed. The MICs of sparfloxacin for P. aeruginosa and E. faecalis were 0.50 mg/L and 0.25 mg/L, respectively, whereas the MICs of ciprofloxacin were 0.25 mg/L for P. aeruginosa and 0.50 mg/L for E. faecalis. PAEs increased as a function of concentration and exposure time. Against E. faecalis no point of maximal response was reached. On the contrary, against P. aeruginosa this point was reached at 8 x MIC of ciprofloxacin and 16 x MIC of sparfloxacin PAE values of sparfloxacin for P. aeruginosa and E. faecalis ranged from 7 to 96 min and from 0 to 112 min, respectively, and those of ciprofloxacin from 8.5 to 82.33 min and from 0 to > 136 min, respectively. Significant PAEs for P. aeruginosa were obtained after 60 min exposure at 4 x MIC (62.6 min) and 2 x MIC (52.6 min) of ciprofloxacin and sparfloxacin, respectively, and at 8 x MIC (81.5 min) and 16 x MIC (81.6 min) for E. faecalis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Infective Agents↗
PubMed1994

Identification of concealed posteroseptal Kent pathways by comparison of ventriculoatrial intervals from apical and posterobasal right ventricular sites.

BACKGROUND: The differential diagnosis of supraventricular tachycardia with concentric atrial activation usually requires the inducibility of sustained tachycardia and needs a complex and time-consuming electrophysiological evaluation. To develop a simple test to establish if ventriculoatrial conduction uses a posteroseptal accessory pathway or the normal conduction system, we compared the ventriculoatrial intervals during right ventricular pacing from apical and posterobasal sites. METHODS AND RESULTS: Continuous pacing was performed from an apical and a posterobasal right ventricular site in 34 patients with retrograde conduction over the normal conduction system (group A) and in 22 patients with conduction over a posteroseptal accessory pathway (group B). During apical pacing, ventriculoatrial intervals in group A (176 +/- 40 milliseconds) were not significantly different than those in group B (197 +/- 47 milliseconds, P = NS). During posterobasal pacing, group B patients had significantly shorter ventriculoatrial intervals than group A patients (158 +/- 46 versus 197 +/- 39 milliseconds, P < .01). The difference between the ventriculoatrial interval obtained during apical pacing and that obtained during posterobasal pacing (ventriculoatrial index) discriminated between the two groups without overlapping: It was positive in all group B patients (39 +/- 19; range, +10 to +70 milliseconds) and negative in all except two group A patients (-21 +/- 13; range, -50 to +5 milliseconds; P < .001). CONCLUSIONS: This ventriculoatrial index can identify accurately and in the absence of tachycardia whether concentric retrograde conduction is proceeding over a posteroseptal accessory pathway or over the normal conduction system.

Adult↗
PubMed1993

Comparison of electrophysiologic effects of quinidine and amiodarone in sustained ventricular tachyarrhythmias associated with coronary artery disease.

Fifteen patients with spontaneous ventricular tachyarrhythmias underwent electrophysiologic studies at baseline and during therapy with quinidine and amiodarone. In 9, ventricular tachycardia (VT) with a similar QRS morphology was induced with quinidine, amiodarone and under the control state. Both quinidine and amiodarone significantly increased QRS duration and the VT cycle length. Amiodarone increased the VT cycle length more than quinidine (85 vs 121 ms, p < 0.05). Amiodarone increased the percent QRS duration (during sinus rhythm, ventricular pacing and VT) significantly less than percent VT cycle length, whereas quinidine did so only at slow rates (at faster rates the percent increase in QRS duration is not different from the percent increase in VT cycle length). The percent increase in QRS duration produced by quinidine correlated significantly with the percent increase in VT cycle length (the best correlation was observed during pacing, r = 0.78). In contrast, no such significant correlations were obtained for amiodarone. Thus, amiodarone prolongs VT cycle length more than quinidine (at the doses used). The effects of quinidine on conduction in tissue mostly unrelated to tachycardia origin predict effects in the tachycardia cycle length. In contrast, the effects of amiodarone on the latter are more intense but not predicted by those on tissue unrelated to the tachycardia origin.

Adult↗
PubMed1993

Patch-clamp recording from Müller (glial) cell endfeet in the intact isolated retina and acutely isolated Müller cells of mouse and guinea-pig.

Müller cells span through the entire retina and terminate with the formation of endfeet at the vitreous body. These endfeet are thought to be specialized for maintaining the K+ homeostasis in the retina based on the assumption that voltage signals can passively spread from the cell body to the endfeet. We employed the patch-clamp technique to study the physiological properties of these endfeet in a retinal wholemount preparation from guinea-pig or mouse. After assessing one endfoot with the patch pipette and establishing the whole cell recording configuration, a membrane area which approximately matched the size of one endfoot and proximal process could be voltage-clamped. This morphological correlation could be established by filling the cytoplasm with the fluorescent dye Lucifer Yellow via the patch-pipette. The morphological, immunocytochemical and ultrastructural inspection of the recorded cells revealed that mouse Müller cell endfeet were connected by only a thin stalk to the proximal process. In contrast, guinea-pig endfeet were connected by thick stalks. The endfoot current in the mouse was dominated by a voltage and time-independent K+ conductance. In contrast, in some of the recordings from guinea-pig, delayed and inwardly rectifying K+ currents were observed. These voltage-gated currents were more frequently observed or were facilitated when the membrane area under voltage clamp was increased, blocking the passive K+ currents by Ba2+ in both, mouse and guinea-pig. We thus assume that the voltage-gated currents were not in the endfeet membrane, but rather in the proximal process and could thus be better activated in the guinea-pig with its thicker stalk or after increasing the membrane area under voltage clamp control. Similar results were obtained in freshly isolated Müller cells; in contrast to the cells from the wholemount the voltage-gated currents were more frequently observed. These studies demonstrate that the Müller cell endfoot of the mouse with its vascularized retina is an electrically isolated unit and that voltage signals do not spread to the proximal process. Such a property would, however, be required for the redistribution of K+ via spatial buffer currents. In contrast, guinea-pig Müller glial cells with their stout morphological connection between endfoot and proximal process are better suited to fulfil this task.

Animals↗
PubMed1993

The importance of antitachycardia pacing for patients presenting with ventricular tachycardia.

The initial experience from electrophysiological studies showed that pacing induced termination of ventricular tachycardias is usually possible but requires a critical pacing sequence. Studies on the resetting phenomenon showed, in most instances of failure of termination, that the "limiting factor" to produce ventricular tachycardia termination is usually failure to produce block within the circuit rather than failure to access or interact with the ventricular tachycardia origin. The resetting response is related to tachycardia termination in a number of ways. Of note is that a steeply increasing resetting pattern usually predicts tachycardia termination. Between 50% and 90% of induced ventricular tachycardias will be terminated by trains of rapid ventricular pacing. The analysis of the pacing rate necessary for termination shows that it varies widely. Paced cycle lengths of < 80% of tachycardia cycle length are necessary in at least 20% of tachycardias. In contrast, the incidence of acceleration is closely related to the paced cycle length: it is negligible with paced cycle lengths over 80% of tachycardia cycle length and increases to 36% with paced cycle lengths below 76% of tachycardia cycle length. Present information about efficacy of antitachycardia pacing in spontaneous tachycardias suggests that it is extremely effective, with over 90% success. However, it is likely that these data correspond to a selected group of tachycardias.

Cardiac Pacing, Artificial↗
PubMed1993

Ventricular fusion during resetting and entrainment of orthodromic supraventricular tachycardia involving septal accessory pathways. Implications for the differential diagnosis with atrioventricular nodal reentry.

BACKGROUND: Ventricular fusion during transient entrainment of orthodromic atrioventricular reciprocating tachycardias (OAVRT) was originally found to be absent and recently observed only with left ventricular stimulation. However, previous studies were restricted to cases with a left free wall accessory pathway. The hypothesis of the present study was that fusion is likely during resetting and entrainment of OAVRT with right ventricular stimulation if the accessory pathway is septally located, since its insertion is relatively close to the stimulation site. This phenomenon can help in the differential diagnosis with atrioventricular nodal reentry (AVNR). METHODS AND RESULTS: We performed programmed right ventricular stimulation during regular inducible supraventricular tachycardia with concentric atrial activation in 44 patients--20 with OAVRT and 24 with AVNR. Fusion in the ECG morphology of extrastimuli producing resetting was observed in 19 of 19 OAVRT but in 0 of 11 AVNR reset (P < .001). Transient entrainment was demonstrated in all 31 cases undergoing rapid ventricular pacing (14 OAVRT and 17 AVNR). Entrainment with fusion occurred in 13 of 14 OAVRT and in 0 of 17 AVNR (P < .001). Fusion was critically dependent on the coupling intervals or pacing rates, sometimes having a narrow window for its observation. CONCLUSIONS: The relative proximity (conduction time) among pacing site, site of entrance to a reentrant circuit, and site of exit from the circuit to the paced chamber are critical for the occurrence of fusion during resetting and/or entrainment. The presence or absence of fusion during these phenomena can help in the differential diagnosis of certain supraventricular tachycardias.

Adolescent↗
PubMed1993

Treatment of ventricular arrhythmias in patients with hypertrophic cardiomyopathy.

In patients with hypertrophic cardiomyopathy, asymptomatic episodes of non-sustained ventricular tachycardia are frequent and of prognostic significance for sudden cardiac death in adults, particularly in those whose consciousness is impaired. Low-dose amiodarone, found to be beneficial in mildly symptomatic non-sustained ventricular tachycardia, but detrimental in a subgroup with prominent non-arrhythmic symptoms, could be an alternative to an electrophysiological approach in patients with syncope but preserved functional capacity. In cardiac arrest survivors, an electrophysiological approach seems preferable to empiric amiodarone, together with implantation of a defibrillator, at least in those in whom inducible arrhythmias cannot be suppressed.

Amiodarone↗
PubMed1991

Contribution of different yeasts isolated from musts of monastrell grapes to the aroma of wine.

Volatile substances of wines obtained by fermentation of musts from 'Monastrell' grapes (Alicante, Spain) was studied for yeast isolated from such musts. The results of the statistical treatment performed show the importance of yeasts of low fermentative power, particularly Kloeckera apiculata, in the production of volatile substances. Saccharomyces cerevisiae var. chevalieri was found to be the most important yeast of high fermentative power.

Chromatography, Gas↗
PubMed1989

[Cerebral cysticercosis. 10 cases].

Ten patients with cerebral cysticercosis seen between 1983 and 1986 were treated with praziquantel and in some cases by a ventriculoperitoneal shunt and/or surgical excision of cysts. Clinical and biological data were of no prognostic value. CT only was useful in orientating therapy and establishing the prognosis. A favorable course was obtained in 7 parenchymatous and meningeal forms, the fatal cases being of the mixed type. Praziquantel was inactive against intraventricular cysts.

Adult↗
PubMed1987

Capillary column gas chromatographic identification of sugars in honey as trimethylsilyl derivatives.

A method for identifying carbohydrates (mono-, di- and trisaccharides) in honey is presented. It is based on the separate preparation of both trimethylsilyl ethers and oxime trimethylsilyl ethers of the sugars followed by their gas chromatographic separation on a fused-silica capillary column coated with OV-101 using temperature programming. From the two chromatograms, the number of peaks given by each derivatized sugar, their relative retention times and peak-area ratios are used for identification. The identities of two unidentified trisaccharide peaks are considered. Quantitative applications to honey sugar analysis are discussed.

Carbohydrates↗