Biomedical subjects

R González

Publications and source records attributed to R González.

At least 19 recordsLinked to original sources

PubMed1992

Inhibitory and contractile effects of okadaic acid on rat uterine muscle.

The effects of okadaic acid and its interactions with various agents known to increase, by different mechanisms, the intracellular levels of cyclic AMP and/or cyclic GMP were investigated in isolated strips of rat myometrium. Okadaic acid showed inhibitory effects at concentrations between 10(-7) M and 3 x 10(-6) M. At higher concentrations, a biphasic, contractile and then relaxant response was observed. The results obtained suggest that, in rat uterine smooth muscle, the inhibitory effects of okadaic acid are not entirely mediated by the activation of cyclic AMP- and/or cyclic GMP-dependent pathways. The data also point to the existence of a clear interaction between okadaic acid and methylxanthines, although further studies are needed to clarify the mechanisms involved in this interaction.

Animals↗

PubMed1992

Cloning, sequence analysis and yeast expression of the egl1 gene from Trichoderma longibrachiatum.

A gene (egl1) encoding an endoglucanase (EGL1) from Trichoderma longibrachiatum has been cloned and sequenced. This gene, homologous to the T. reesei egl1 gene, differs from it in the length of the introns (particularly the first one) and encoded protein. A cDNA fragment obtained by the rapid amplification of cDNA ends method, which takes advantage of the polymerase chain reaction, has been expressed in yeast under control of the cyc-gal inducible promoter and yeast clones able to secrete active enzyme have been obtained.

Amino Acid Sequence↗

PubMed1992

Hepatoprotective effects of lobenzarit disodium on acetaminophen-induced liver damage in mice.

We have studied the effects of the immunomodulator drug lobenzarit in the model of acute hepatotoxicity induced by a high oral dose (600 mg/kg) of acetaminophen in mice. Lobenzarit at doses of 25, 50 and 100 mg/kg i.p. decreased significantly the activity of alanine aminotransferase in serum, which was increased by acetaminophen alone, and increased the concentration of reduced glutathione in mice liver, which is depleted by acetaminophen. Lobenzarit also reduced liver damage induced by acetaminophen in mice, which was observed by electron microscopy. The hepatoprotective effects of lobenzarit were dose-dependent and they were produced when lobenzarit was administered 30 min before acetaminophen or 2 and 4 h after it. It is concluded that lobenzarit exerts some effects which resemble those of an antidote of acetaminophen such as N-acetylcysteine.

Acetaminophen↗

PubMed1992

Respiratory allergy to Aspergillus-derived enzymes in bakers' asthma.

Baking and food industry workers are exposed to several powdered Aspergillus-derived enzymes with carbohydrate-cleaving activity that are commonly used to enhance baked products. We describe a retrospective study of sensitization to fungal alpha-amylase and cellulase on bakers. Five bakers in whom respiratory allergy symptoms developed when they were exposed to bread "improvers" that contained fungal alpha-amylase and cellulase were investigated by in vivo and in vitro tests. Type I hypersensitivity to these enzymes was demonstrated in the five patients by means of skin testing, histamine release test, positive reverse enzyme-immunoassay for specific IgE antibodies, and bronchial provocation test response to alpha-amylase or cellulase or both. Isolated immediate and dual responses to the bronchial challenge tests with these enzymes were observed. Immunoblot analysis with use of a pooled serum identified IgE-binding components in both enzymes. In the reverse-enzyme immunoassay-inhibition assays cross-reactivity between alpha-amylase and cellulase was not found, but some degree of cross-reactivity between alpha-amylase and A. oryzae, and between cellulase and A. niger was demonstrated. Four of the patients were also sensitized to cereal flour. Aspergillus-derived enzymes used as flour additives can elicit IgE-mediated respiratory allergy, and this fact has to be considered in the diagnosis and clinical management of bakers' asthma.

Adolescent↗

PubMed1992

Morphometric analysis of GH-immunoreactive cells after GH release induced by treatment with estrogen in adult male rats.

In order to elucidate the response of somatotropic cells to the influence of gonadal steroids on the regulation of growth hormone secretory patterns, a morphometric analysis was carried out on the GH-immunoreactive cells of adult male rats treated chronically with intramuscular injections of estradiol valerate. The morphometric and morphological results obtained were correlated to the serum levels of GH at the moment of sacrifice. Treatment with a daily dose of 125 micrograms of estradiol vaterate over 15 d was seen to lead to an increase (p less than 0.01) in the serum GH values accompanied by a decrease in the intensity of reaction of the GH-cells and, morphometrically, a reduction in their size (p less than 0.01) due to a decrease in the cytoplasmic area (p less than 0.01), but without significant changes in the nuclear area. Our results suggest that in male rats estrogens enhance the release of the intracellular GH pool but that they do not affect hormone synthesis to a great extent.

Analysis of Variance↗

PubMed1992

Purification and characterization of major inhalant allergens from soybean hulls.

Proteins responsible for respiratory allergy to soybean have been purified from an extract of soybean hulls. The purification procedure combined size exclusion and reverse-phase HPLC. Two pure glycoproteins (S1 and S2) exhibiting IgE-binding ability, as demonstrated by immunoblotting and ELISA techniques, were obtained. Both proteins displayed low molecular weight values on SDS-PAGE (S1, 7.0 kD; S2 7.5 kD). Protein S1 showed charge microheterogeneity, rendering two bands at pH 6.1-6.2 on IEF, whereas S2 showed a single band at pH 6.8. Amino acid composition analyses revealed a strong homology between S1 and S2 and, as a characteristic feature, a high percentage of hydrophobic residues, mainly leucine and isoleucine. Concerning the allergenic activity, both proteins were recognized by the specific IgE from 95% of patients who suffered asthma attacks during the asthma outbreaks of 1987 and 1988 in Cartagena (Spain), caused by soybean dust. Besides, proteins S1 and S2 were able to, separately, inhibit up to 75% the binding of specific IgE to the whole extract. Moreover, purified proteins totally crossreacted, even though protein S2 seemed to be slightly more active in all the immunochemical techniques employed. Results presented allow us to conclude that both proteins are isoallergens and to name them as Gly m IA (protein S2) and Gly m IB (protein S1), according to the IUIS-allergen nomenclature system.

Allergens↗

PubMed1992

Endothelial modulation of the ouabain-induced contraction in human placental vessels.

Ouabain (1 x 10(-7)-3 x 10(-5) M) elicited concentration-dependent vasoconstriction in human placental arteries and veins. These responses, but not those produced by 10(-6) M 5-hydroxytryptamine, were increased after the removal of vascular endothelium. In placental arteries, the respective blockade of cyclooxygenase or lipoxygenase with indomethacin of 5,8,11,15-eicosatetraynoic acid as well as the inactivation of nitric oxide with phenidone or oxyhemoglobin and the inhibition of nitric oxide synthesis with NG-monomethyl L-arginine (all at 10(-5) M) did not mimic the effects of endothelial denudation on ouabain-evoked contractions. Bioassay experiments suggested that the above-mentioned endothelial effects are mediated by diffusible factors. 86Rb+ uptake, a method to measure sodium pump activity, was significantly reduced by the removal of endothelium. These results suggest the existence of an inhibitory modulation by the endothelium of the contractions induced by ouabain, likely mediated by a diffusible factor(s) released from these cells. The nature of this substance is unknown but is not related to prostaglandins or leukotrienes, and neither is it a nitric oxide-related compound. Its mechanism of action could be stimulating the activity of vascular sodium pump and/or antagonizing its inhibition by ouabain.

5,8,11,14-Eicosatetraynoic Acid↗

PubMed1992

[Arrhythmogenic dysplasia of the right ventricle: clinical presentation and long-term course].

The clinical findings and follow up in 10 patients with arrhythmogenic dysplasia of the right ventricle were analyzed. Presentation occurred at a mean age of 35 +/- 12(SD) years and all patients presented with ventricular tachycardia and a left bundle branch block pattern. Physical examination was normal. T waves were inverted in right precordial leads in all and late depolarization were seen in 7. Global or segmental dilatation of the right ventricle was shown by echocardiogram in all patients and by right ventricular angiography in 8. After a mean follow up of 6.6 years (+/- 3), 70% had recurrence of ventricular tachycardia in spite of adequate antiarrhythmic therapy. Mortality was only 10%. Surgery was performed in 4 patients. Two patients had focal right ventricular fibrosis and resection lead to cure of arrhythmia.

Adult↗

PubMed1992

[DDD dual chamber pacemakers. Initial experience].

Our preliminary experience with dual-chamber DDD pacemakers is reported. Technological innovations of the device, atrio-ventricular electrode stability and sequential stimulation have contributed to improve the conditions of patients previously submitted to VVI pacemaker implantation. Primary indications for DDD pacemaker implantation in our series included 7 patients with complete atrio-ventricular (A-V) block, 3 with Mobitz type II second-degree A-V block and 2 with sick sinus syndrome. In six of the 12 patients (50%) additional indications included: ventricular tachycardia in 4 patients, atrial fibrillation in one and pacemaker syndrome in one. Other cardiac conditions were diagnosed: dilated cardiomyopathy in 3 patients, ischemic heart disease in 2 patients, valvular heart disease in 2 patients, congenital heart disease in 1 patient and hypertrophic cardiomyopathy in one patient. The implanted pacemakers were: 5 Genesis, 4 Ultra CPI and 3 Versatrax. J-shaped atrial electrodes were used in 8 patients and in 4 instances a screw-in electrode was employed. Improvement of hemodynamic function was achieved by frequent follow up and reprogramming of DDD pacemaker in every patient. While 4 patients died with progressive deterioration of cardiac function, eight patients survived with adequate sequential stimulation. We conclude that DDD pacemakers are reliable and afford symptomatic relief in a broad spectrum of patients.

Adult↗

PubMed1992

[Radiofrequency fulguration in patients with reciprocating tachycardias].

The use of radiofrequency for catheter ablation of accessory pathways and dual AV nodal pathways has been recently introduced. In this paper the results obtained in 5 patients are reported. Three patients had accessory pathways and 2 a dual AV nodal pathway. After a complete electrophysiologic study, a 7F Door Knob catheter coupled to a Radionics radiofrequency generator delivering a maximum of 16 watt at 480 KH was used to ablate the abnormal pathway. Success was obtained in every patient at times varying from 30 sec to 3 min, using 3 to 17 energy deliveries. These results include the first successful ablation of a left lateral bundle with radiofrequency using an energy of only 16 Watt.

Adolescent↗

PubMed1992

Morphometric changes in GH-immunoreactive adenohypophyseal cells induced by intraventricular administration of colchicine to adult rats.

In order to elucidate whether the gender differences observed in the somatotropic cells of adult rats are mediated by hypothalamic neuropeptides, a morphometric analysis was made of the GH-immunoreactive cells of adult rats treated intraventricularly with colchicine. The morphometric and morphological findings obtained were correlated to the basal serum levels of GH at the time of sacrifice. Treatment with colchicine was seen to increase serum GH levels; this increase was accompanied by an increase in the intensity of the reaction of the GH-cells and, morphometrically, an increase in their size due to an increase in the nuclear area, but with no significant changes in the cytoplasmic area. The results suggest that in the absence of somatostatin and GRF the basal release of GH is elevated in a similar fashion in both sexes, in turn suggesting that gonadal steroids might act at hypothalamic level on the release of somatostatin and, indirectly, on the intracellular pool of GH and hormonal secretion.

Animals↗

PubMed1992

Beta 2 microglobulin in CAPD.

The peritoneal clearance (Kp) and renal clearance (Kr) of beta 2 microglobulin (beta 2 m) were studied prospectively on 50 ESRD patients treated with CAPD, in order to determine the effect of the number of daily exchanges on Kp and to investigate the factors which influence the serum levels of beta 2m. Kr and Kp of beta 2m and creatinine (Cr) were calculated using standard formulae at the initiation of study and again at 6, 12, 18 and 24 months by collecting 24 hour urinary output and dialysate effluent. Kp of beta 2m of patients on 3 exchanges/day was .94 +/- .08 ml/min at the initiation of study and 1.1 +/- .08 at the end. For patients on 4 exchanges/day it was .99 +/- .14 ml/min and 1.1 +/- .12 respectively. There was no significant difference. Serum levels of beta 2m were lower on patients with significant residual renal function (RRF) (17 +/- .9 mg/L) than on patients without RRF (38 +/- 2 mg/L. p = .001). Serum levels of beta 2m correlated inversely with Kr of Cr and beta 2m at the initiation of study and at the end (r = .67 and .77 respectively, p = .0001). We conclude that serum levels of beta 2m correlate inversely with Kr of Cr and are expected to rise as RRF decreases. The combined peritoneal and renal excretion of beta 2m is less than its daily production. The number of dialysis exchanges does not influence Kp of beta 2m.

Adult↗

PubMed1992

Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin.

Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.

Animals↗

PubMed1991

Effect of endothelin on total and regional coronary resistance and on myocardial contractility.

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.

Animals↗

PubMed1991

Estrogenic modulation of met-enkephalin-induced prolactin secretion in rats.

In order to elucidate the possible role of estrogens in the sex-dependent modulation of met-enkephalin-induced prolactin secretion, and the cellular response at adenohypophyseal level, analyses of serum prolactin levels together with a morphometric study of prolactin-immunoreactive cells were carried out following intraventricular administration of the opioid to estrogen-primed male rats. Administration of the opioid led to an increase in the serum levels of the hormone and, morphometrically, a significant increase in the cellular, cytoplasmic and nuclear areas was observed. When naloxone was administered previously, the above, mentioned changes did not appear, and the values found were similar to those observed in the animals treated only with estrogens. The results suggest that the metenkephalin-induced prolactin secretion is modulated by the gonadal steroid environment.

Animals↗

PubMed1991

Drugs effects on superoxide generation and chemiluminescence response of human leukocytes.

Luminol-enhanced chemiluminescence was used to determine the effects of diethyldithiocarbamate, dipyridamole, catechin and verapamil on the generation of reactive oxygen species in human leukocytes, and on superoxide generated by chemiluminescence of the hypoxanthine xanthine-oxidase reaction. These agents reduced the luminol enhanced chemiluminescence response of activated leukocytes, most probably by inhibiting the superoxide generation reaction. On the other hand, citrate and diethylcarbamazine, produced a slight increase of the luminol enhanced chemiluminescence of leukocytes.

Catechin↗

PubMed1991

Prognostic indicators of chronic chagasic cardiopathy.

After 104 patients with positive serology for Chagas' disease had been followed for a decade, a selection of 66 patients was made from this number and a total of 25 variables obtained from clinical and paraclinical findings were analyzed, with the purpose of knowing which of these variables may be of help, in time, in determining prognosis. The information was analyzed using the Cox regression model. The patients were classified into groups according to the results in the invasive and noninvasive studies: those with a normal electrocardiogram without heart disease (14 patients) or with early segmental abnormalities of the left ventricle (9 patients); those with an abnormal electrocardiogram and advanced myocardial damage but without signs of congestive heart failure (26 patients); and those with an abnormal electrocardiogram together with congestive heart failure (17 patients). Of these patients, those with electrocardiographic abnormalities correspond to stages of the disease where advanced myocardial damage is proven. There was a 42% mortality during the follow-up of these patients. According to the regression model, the value of the systolic blood pressure is a good predictor of mortality (P = 0.0380) in those with congestive heart failure. When we analyzed jointly the patients with an abnormal electrocardiogram, we found that several variables (systolic blood pressure, the presence of atrial fibrillation, the radiologic cardiothoracic index, and left ventricular end-diastolic volume obtained by the ventriculogram), were negatively correlated with regard to survival. This last model has a chi-square of 11.36 (P = 0.0228). These models allow us to predict the prognosis in this group of patients with Chagas' disease and advanced myocardial damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Characterization of acetylcholinesterase from human heart auricles: evidence for the presence of a G-form sensitive to phosphatidylinositol-specific phospholipase c.

1. Acetylcholinesterase (AChE) is an important enzyme of the cholinergic system in mammals. 2. We report here the subcellular association of the AChE molecular forms in the normal human heart auricle. 3. Both globular (G) and asymmetric (A) forms were identified using velocity sedimentation and sequential extraction procedures. 4. G forms corresponds to 84% and A forms account for 16% of the total AChE activity. 5. Of G forms 64% of AChE activity correspond to the G1 monomer and of the A forms the class I-A account for 80% of AChE activity. 6. In addition, treatment of the cardiac membranes with the enzyme phosphatidylinositol-specific phospholipase c (PIPLC) results in the solubilization of AChE activity. 7. This means that a G2 AChE dimer with a glycolipid anchoring domain is present in the human heart.

Acetylcholinesterase↗