Browsing by Author "GONZALEZ, R"

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    CHARACTERIZATION OF ACETYLCHOLINESTERASE FROM HUMAN HEART AURICLES - EVIDENCE FOR THE PRESENCE OF A G-FORM SENSITIVE TO PHOSPHATIDYLINOSITOL-SPECIFIC PHOSPHOLIPASE-C
    (1991) GONZALEZ, R; CAMPOS, EO; MORAN, S; INESTROSA, NC
    1. Acetylcholinesterase (AChE) is an important enzyme of the cholinergic system in mammals.
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    EFFECT OF A CALCIUM INHIBITOR, NIFEDIPINE, ON EXERCISE TOLERANCE IN PATIENTS WITH ANGINA-PECTORIS - A DOUBLE-BLIND-STUDY
    (1981) CORBALAN, R; GONZALEZ, R; CHAMORRO, G; MUNOZ, M; RODRIGUEZ, JA; CASANEGRA, P
    The effect of nifedipine on exercise tolerance was studied in 30 patients with stable angina and positive graded exercise testing. Treadmill exercise testing was performed on each of 5 consecutive days. Placebo or nifedipine, 10 mg sublingually, was given 30 min before exercise on the 3rd day. The following day the intervention was reversed in a double-blind manner. Angina was abolished by nifedipine but not by placebo in 12 patients (40%). The time to onset of angina in the remaining patients increased from 4.1 .+-. 0.4 (SEM [standard error of mean]) to 6.7 .+-. 0.6 min (P < 0.001). Time to ST depression .gtoreq. 2 mm increased from 4.0 .+-. 0.3 to 5.4 .+-. 0.5 min, while duration of exercise increased from 6.3 .+-. 0.3 to 8.2 .+-. 0.4 min (P < 0.001). The maximum heart rate was 145 .+-. 3.3 with nifedipine and 122 .+-. 3.8 min-1 with placebo (P < 0.01). Resting systolic blood pressure decreased 30 min after nifedipine administration from 131 .+-. 3.4 to 106 .+-. 2.9 mm Hg (P < 0.01). Maximal systolic blood pressure during exercise was lower with nifedipine (127 .+-. 4.8 mm Hg) than with placebo (155 .+-. 8.6 mm Hg, P < 0.01). Nifedipine significantly improves the exercise tolerance of patients with stable angina pectoris by decreasing peripheral vascular resistance and myocardial O2 demand.
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    EFFECT OF ENDOTHELIN ON TOTAL AND REGIONAL CORONARY RESISTANCE AND ON MYOCARDIAL-CONTRACTILITY
    (1991) DOMENECH, R; MACHO, P; GONZALEZ, R; HUIDOBROTORO, JP
    Endothelin is a 21-amino acid peptide produced by the endothelium and has a potent vasoconstrictor effect. Because of the importance of the endothelium on vasomotor regulation, we studied the effect of endothelin on total and regional coronary vascular resistance and on myocardial contractility in the intact heart of anesthetized dogs. Intracoronary administration of 2 to 80 pmol/kg of endothelin produced a dose-dependent increase in coronary resistance, ischaemic decrease in myocardial contractility and atrium-ventricular blockade. The increase in resistance was greater towards the outer layer of the left ventricular wall. When the coronaries were perfused at a constant rate and vasoconstriction was prevented with adenosine or nitroglycerine, endothelin did not produce inotropic changes. These results show that endothelin is a potent vasoconstrictor of the resistance coronary vessels, producing a redistribution of transmural blood flow and a decrease in myocardial contractility secondary to ischaemia.
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    EFFECT OF EXOGENOUS SEX STEROIDS UPON THE NUMBER OF GERM-CELLS AND THE GROWTH OF FETAL OVARIES GRAFTED UNDER THE KIDNEY CAPSULE OF ADULT OVARIECTOMIZED HAMSTERS
    (1983) ARRAU, J; ROBLERO, L; CURY, M; GONZALEZ, R
    Effect of estradiol (E), progesterone (P) and testosterone propionate (T) upon growth and germ cell population of fetal ovaries transplanted under the kidney capsule of adult ovariectomized hamsters was examined. Fetal ovaries were obtained 15 days postcoitum and the host received daily s.c. injections of E (1 .mu.g/day), P (5 mg/day), T (500 .mu.g/day) or E + P in 0.1 ml oil for 25 days beginning 5 days before grafting. One day after the last injection, the size of the ovary, the germ cell population and plasma steroid levels were assessed. Results of hormone assays indicate that daily steroid administration was able to maintain continuously elevated plasma levels of the corresponding hormone. Interconversions or steroid secretion by the graft, if any, were not reflected in the peripheral circulation. Growth of the graft was stimulated by T and inhibited by P, in comparison with E and oil-treated controls. All germ cells were at the stage of primary-oocyte-forming part of a primordial or growing follicle. Their absolute number was significantly increased by T and E and significantly decreased by P and E + P. The number of oocytes per mm3 of ovary was increased 80, 48 and 40% with E, T and E + P, respectively. In the hamster, exogenous sex steroids given to the host can exert specific effects upon the growth and oocyte population of a grafted fetal ovary. Whether or not the action of steroids upon the graft is a direct one and whether they influenced oogonial mitosis, the evolution of the meiotic prophase or atresia of primary oocytes remains to be determined.
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    ENDOSCOPIC INTRASPHINCTERIC INJECTION OF BOTULINUM TOXIN FOR THE TREATMENT OF ACHALASIA
    (LIPPINCOTT-RAVEN PUBL, 1995) ROLLAN, A; GONZALEZ, R; CARVAJAL, S; CHIANALE, J
    Three patients with achalasia were treated with endoscopic injection of botulinum toxin (BoTx). BoTx (80 U) was injected via a sclerotherapy needle into the lower esophageal sphincter (LES). One patient complained of transient heartburn that resolved after omeprazole treatment. Two patients reported sustained symptomatic improvement. They were able to eat normally 48 h after treatment and have remained symptom free for 5 and 6.5 months, respectively. In these patients, esophageal manometry 4 months after treatment showed a marked reduction of resting LES pressure and the appearance of a previously absent LES relaxation after swallowing. The third patient had only a transient clinical improvement, with occasional dysphagia beginning 3 months after treatment. All patients showed unchanged aperistalsis of the esophageal body. Its less invasive nature compared with other therapeutic alternatives may give BoTX injection a role in the treatment of some patients with achalasia.
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    ISOLATION OF PROTEOGLYCANS SYNTHESIZED BY RAT-HEART - EVIDENCE FOR THE PRESENCE OF SEVERAL DISTINCT FORMS
    (1992) GONZALEZ, R; URREA, R; GONZALEZ, M; INESTROSA, NC; BRANDAN, E
    1. The proteoglycans (Ps) synthesized by auricle and ventricle from adult rat
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    MULTIPLE PATHWAY TACHYCARDIAS - ELECTROPHYSIOLOGICAL PROPERTIES AND FULGURATION OF ACCESSORY PATHWAYS IN 2 PATIENTS
    (1994) GONZALEZ, R; FAJURI, A; NEHGME, R; CAMBON, AM
    We report two patients (male, 35 and female, 28 years old) with recurrent and refractory tachycardias referred for an alectrophysiological study. EKG showed left lateral accessory pathway in both, two tachycardias with identical morphology but with different frequency and activation sequence were detected. One was orthodromic with anterograde conduction by the His-Purkinje budle and retrograde by the accesory pathway and the other with slow nodal anterograde conduction. The accesory pathway was first fulgurated with radiofrequency at the third attempt. Posteriorly, a nodal reentry tachycardia was induced in the first patient and in the second, a double nodal pathway was confirmed. In both, the slow pathway was modified using Jackman's technique, after three and four attempts respectively. After these applications, the induction of tachycardia with programmed atrial or ventricular stimulation, with or without Isoproterenol, was not possible It is concluded that radiofrequency fulguration is a reasonable therapeutic alternative for patients with multiple circuit tachycardias
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    ROLE OF PROGRAMMED ELECTRICAL-STIMULATION OF THE HEART IN RISK STRATIFICATION POST-MYOCARDIAL INFARCTION
    (1988) GONZALEZ, R; ARRIAGADA, D; CORBALAN, R; CHAMORRO, G; FAJURI, A; RODRIGUEZ, JA