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Biomedical subjects

R Garcia

Publications and source records attributed to R Garcia.

At least 451 records · Page 25Linked to original sources
PubMed1983

The subcellular localization of ubiquinone in human neutrophils.

Ubiquinone-10 has recently been proposed as a component of the microbicidal oxidase system of neutrophil leukocytes [Crawford & Schneider (1982) J. Biol. Chem. 257, 6662-6668]. We have determined the subcellular localization of ubiquinone and could detect it only in the mitochondrial fractions. It was not enriched in phagolysosomes which were enriched in O2-. generating activity and cytochrome b-245. It is proposed that ubiquinone is unlikely to play a direct role in the electron transport chain located in the plasma membrane which functions to produce microbicidal oxygen radicals.

Centrifugation, Density Gradient↗
PubMed1983

Purification of three rat atrial natriuretic factors and their amino acid composition.

A natriuretic factor has been described in the specific granules of rat atria. We have purified three factors which seem to be low-Mr peptides. They have been purified by means of acid extraction, octadecyl Sep-Pak cartridges, and chromatography on Bio-Gel P-10, CM Bio-Gel A, Mono S and reverse-phase high-performance liquid chromatography columns. The factors contain 26, 31 and 33 amino acids and may have been partially degraded during isolation. They are all 3 biologically active and the shorter one is the most active with a specific activity of 450 000 units/mg.

Amino Acids↗
PubMed1983

Echo-phonocardiographic features of regurgitant porcine mitral and tricuspid valves presenting with musical murmurs.

Echophonographic findings of three patients with spontaneous degeneration of porcine tricuspid and mitral valves presenting with musical murmurs are reported. Echocardiography in all these patients revealed systolic or diastolic cusp flutter similar in frequency to the musical murmur on simultaneously recorded phonocardiogram. Porcine tricuspid regurgitation is usually well tolerated and can be followed clinically for many years. However, patients with mitral porcine valves usually become symptomatic or present with congestive heart failure and usually require valve surgery soon after clinical or echo-phonocardiographic findings of valve regurgitation appear.

Aged↗
PubMed1983

Broad QRS tachycardia: electrocardiographic diagnosis and management.

The diagnostic difficulties between supraventricular tachyarrhythmias with intraventricular conduction delay and ventricular tachycardia have challenged the physician since the first recording of a ventricular tachycardia by Lewis in 1909. The examples selected emphasize some of the diagnostic and therapeutic dilemmas of "broad QRS tachycardias" and their major differential features from abberrancy. Multiple simultaneous surface ECG leads are valuable in showing the direction of the initial activation forces of the QRS complexes, the frontal QRS axis and the configuration of the QRS in lead V1. Vagal maneuvers and intra-atrial or esophageal leads are very useful in demonstrating the underlying atrial rhythm and atrioventricular dissociation when present. In life-threatening situations, urgent therapy or D.C. cardioversion may be required before a definitive diagnosis has been established. In recent years electrode catheter techniques for the diagnosis, for arrhythmia induction and for the selection and assessment of the effectiveness of the antiarrhythmic drug therapy have been carried out in the management of recurrent broad QRS tachycardia. In view of the inherent risks with the use of this invasive technique, it should be restricted to a carefully selected number of patients with recurrent life-threatening dysrhythmias as suggested by Scheinman.

Adult↗
PubMed1983

Role of the ovary in the regulation of sex hormone binding globulin and its contribution to peripheral levels of androstenedione.

In order to assess the role of the ovary in the regulation of the levels of the sex-hormone-binding-globulin (SHBG) and its contribution to peripheral levels of androstenedione, three subject groups were studied: 10 normally menstruating women, 8 postmenopausic women, and 8 postmenopausic ovariectomized women. A basal venous blood sample was drawn between 8:00 to 9:00 h from all subjects in the latter two groups. The blood samples were drawn from the normally menstruating women on days 7, 14, 21 and 28 of their cycles. The following determinations were made in each sample: oestradiol, progesterone, testosterone, androstenedione SHBG, FSH and LH. It was concluded that: 1) SHBG does not vary during the menstrual cycle, nor there are significant differences between postmenopausic and castrated women, and 2) androstenedione levels in castrated women are significantly different from both postmenopausic and normally menstruating women.

Adult↗
PubMed1983

Role of the pituitary in the effects of tonin on adrenal secretion of the rat.

Chronically catheterized conscious rats were infused intravenously with tonin at 2.4 and 12 micrograms x kg-1 x min-1 for 2 h. Plasma aldosterone concentration (PAC) at the end of the experiment was 11.2 +/- 2.4 ng% in controls, 8.5 +/- 2.8 ng% in rats infused with tonin at the lower rate, and 26.2 +/- 3.6 ng% (p less than 0.01 vs. controls) in rats infused at the higher rate. Plasma corticosterone (PC) was significantly higher (p less than 0.05) in the group infused at the high rate while plasma renin activity (PRA) was significantly reduced in this group of rats. Plasma angiotensin II (AII) concentration was similar in all three groups. PAC was elevated after tonin infusion in the presence of AII blockade. PAC in conscious sodium-depleted rats infused with tonin was not significantly changed, but PRA was significantly reduced (p less than 0.01). In chronically hypophysectomized rats, PAC remained unchanged by tonin infusion. The failure of tonin to stimulate aldosterone in hypophysectomized animals indicates a role of a pituitary hormone (probably ACTH) in the effect of tonin on adrenal secretion.

Adrenal Glands↗
PubMed1983

Kallikrein concentration in submandibular glands of rats chronically treated with isoproterenol.

The effect of chronic beta-adrenergic stimulation with isoproterenol on the kallikrein content of rat submandibular gland was estimated by radioimmunoassay, by immunohistochemistry, and by analytical isoelectric focusing. Radioimmunoassays revealed that the kallikrein content of the submandibular gland was already significantly decreased after 6 days of treatment. After 21 days, the kallikrein content was 40 times lower and by 33 days an almost complete depletion was found. These findings were confirmed by immunohistochemistry. Analytical isoelectric focusing also showed that, after 33 days of treatment, the typical bands corresponding to the kallikrein isoenzymes of the submandibular gland had disappeared. These results indicate that kallikrein secretion is influenced by beta-adrenergic stimulation.

Animals↗
PubMed1983

Effect of a potassium-deficient diet on arterial blood pressure, plasma and tissue cations, and tissue norepinephrine in the hypertensive dog.

Chronic potassium deficiency in one-kidney one-clip hypertensive dogs significantly reduces blood pressure and plasma potassium, with a simultaneous increase in plasma renin activity. Tissue potassium concentration was decreased and tissue sodium concentration was increased in striated muscle and adrenal glands, which may suggest that the sodium-potassium pump was inhibited. In myocardium the sodium concentration was higher but the potassium concentration was not significantly lower than in control hypertensive dogs on normal diets. Arterial cation concentrations in the potassium-deficient group were not significantly different from those in the control group. Tissue norepinephrine concentration was higher in arteries from potassium-deficient animals, significantly so in the mesenteric and femoral arteries. The conclusion is that potassium deficiency may decrease blood pressure in the one-kidney one-clip hypertensive dogs by impairing the release of norepinephrine.

Animals↗
PubMed1983

Release of tonin and of kallikrein by perfused rat submaxillary gland.

The release of tonin and kallikrein was investigated in the venous effluent of the perfused rat submaxillary gland (SMG). The SMG was perfused through the common carotid artery after all branches except the SMG artery had been ligated. The venous outflow was collected from the SMG vein. The contralateral nonperfused gland was used as control. The infusion of isoproterenol increased tonin release without affecting its concentration in the SMG. Theophylline increases both tonin secretion and tonin concentration in the SMG. These results suggest that beta-adrenergic stimulation enhances tonin release by increasing synthesis in the SMG, and that these effects might be mediated by cAMP. The infusion of norepinephrine did not affect either tonin release or tonin concentration in the gland. Kallikrein release was significantly increased by norepinephrine, isoproterenol, and theophylline. However, whereas alpha-stimulation produced a significant decrease in kallikrein concentration in the stimulated SMG, beta-adrenergic and theophylline stimulation produced no significant changes in tissue kallikrein. These results suggest that alpha-adrenergic stimulation increases kallikrein release by depleting the enzyme from the gland, whereas beta-adrenergic stimulation might increase kallikrein release by stimulating its synthesis in the gland.

Animals↗
PubMed1983

Extrarenal angiotensin-forming enzymes.

There are two types of enzymes in tissues leading to angiotensin formation: a) those resulting in the formation of angiotensin I, such as renin and cathepsin D, the presence of which is now well established for brain tissue and b) Those leading to the direct formation of angiotensin II without the angiotensin I step, such as cathepsin G and tonin. Recent findings concerning tonin, a serine protease, are described: a) 80% of its amino acid sequence, b) its different characteristics from other serine proteases, from renin, cathepsin D and the angiotensin I converting enzyme, c) the activation of inactive renin, d) its involvement in the 1K-1C hypertensive rats, e) the demonstration of its presence in the distal tubular cells of the rat kidney, and finally, f) its presence in urine and the influence of age and of sodium intake on its urinary excretion.

Amino Acids↗
PubMed1983

Significance of hydatid immunodiagnostic surveys to health care and estimation of prevalence in the Argentine Province of Chubut.

More hydatidosis cases were detected in an immunodiagnostic survey of rural schoolchildren from an endemic area in Argentina by the arc 5 double diffusion (DD5) test than by indirect hemagglutination (IHA) and latex agglutination (LA) tests. Evidence of infection was obtained by clinical, radiologic, echographic, and/or computerized axial tomography examinations in only one of three DD5-negative individuals, and in 2 of 4 students showing a questionable reaction of identity with arc 5 in DD5, who were positive in LA and/or IHA. In contrast, cysts could be demonstrated in all DD5-positive cases, whether positive or negative in the agglutination procedures. These cysts in DD5-positive cases included the smallest cysts (1-1.2 cm wide) detected in surveys to date. Comparison of data obtained in the immunodiagnostic survey and in a review of hospital records was used to assess the relative contribution of each method in estimating the prevalence of infection. The findings are discussed in terms of the advantages and limitations of carrying out immunodiagnostic surveys of residents of endemic areas for purposes of primary medical care and surveillance.

Adolescent↗
PubMed1983

Tyrosine serum levels during anesthesia with high doses of fentanyl.

Serum tyrosine levels were determined in two groups of women. First group included 30 healthy volunteers and the second group was formed by 83 patients submitted to gynecological surgery under anesthesia with fentanyl (0.05 mg/kg). The results showed that preoperative tyrosine levels were higher than control values and decreased under fentanyl anesthesia. Surgical stimulation did not modify tyrosine levels. When surgery was ended serum tyrosine levels reached control values. Under fentanyl-anesthesia a direct relationship between serum tyrosine levels, cardiovascular parameters and catecholamine changes as reported by other authors is suggested. We think tyrosine serum determination could be an indirect, easy and unexpensive measure of hormonal stress response.

Adult↗
PubMed1982

The association of FAD with the cytochrome b-245 of human neutrophils.

A plasma membrane fraction prepared from human neutrophils had a fluorescence resembling that of a fluorescent flavoprotein, with emission maximum near 520nm and excitation maxima near 380 and 460nm. The fluorescence emission and excitation properties of Triton N-101-solubilized membrane fraction resembled those of FAD. FAD was present in the membranes at a concentration of 417pmol/mg of protein and cytochrome b(-245) at a concentration of 407pmol/mg of protein. In a 110-fold purified preparation of cytochrome b(-245) the ratio of FAD:cytochrome b was 1:1. Analytical gradient centrifugation of neutrophil homogenates shows a coincidence of two cytochrome b peaks and two peaks of fluorescence, corresponding with plasma membrane and specific granule fractions; most of the FAD was non-fluorescent and located in fractions lighter than the plasma membrane. Plasma membrane fractions prepared from neutrophils of patients suffering from the X-linked form of chronic granulomatous disease lacked cytochrome b and contained 194pmol of FAD/mg of protein; plasma membrane fractions prepared from neutrophils of patients with the autosomal recessive form of chronic granulomatous disease contained both cytochrome b(-245) and FAD in the normal range of concentrations in a ratio of 1:1. Phagocytic vesicles were prepared from normal neutrophils and found to contain FAD and cytochrome b in a ratio 2.22:1, suggesting that activation of neutrophils many involve the incorporation of an additional flavin into the membrane. Under anaerobic conditions in the presence of EDTA to act as an electron donor to a flavin, the cytochrome b(-245) of neutrophil membranes was partly (12%) photoreducible, an effect increased to 100% by the addition of FMN. The extent of reduction of cytochrome b in an anaerobic neutrophil homogenate containing NADH increased from 30% to 70% on illumination. We suggest that these results indicate a close association between FAD and cytochrome b(-245) and support a scheme for electron transport thus: [Formula: see text]

Cell Membrane↗
PubMed1982

Immunohistochemical localization of tonin in rat salivary glands and kidney.

Tonin has been localized in salivary glands and kidney by the indirect immunofluorescence technique of Coons and by the unlabeled antibody technique of Sternberger. Both techniques gave identical results. Immunoreactive tonin was localized in the cytoplasm of granular convoluted tubular cells and on the apical surface of striated duct cells and collecting duct cells of the submandibular gland. In the parotid and sublingual glands, which lack granular cells, tonin was only found on the apical surface of striated duct and collecting duct cells. In the kidney, immunoreactive tonin was found only associated with cells of the distal convoluted tubules. After fixation with Bouin fluid or with ethanol, tonin was found not only on the apical surface of the cells but also in the apical and perinuclear cytoplasm. This cytoplasmic staining has been attributed to artefactual diffusion since, after fixation with formol-picric acid, the enzyme could only be localized on the apical surface of the tubular cells.

Aging↗
PubMed1982

Inhibition of dibutyryl cyclic AMP induced steroidogenesis in rat adrenocortical cells by the putative calcium antagonist TMB-8.

A significant proportion of the steroidogenic response of isolated rat adrenocortical cells to dibutyryl cyclic AMP does not require extracellular calcium, and this component is profoundly depressed by low concentrations of the putative calcium antagonist, TMB-8. The inhibition is reversed by either the readdition of calcium or the calcium ionophore A23187. The steroidogenic response to pregnenolone, whose mode of action does not require calcium, was not depressed by TMB-8. Corticotropin (ACTH)-induced steroidogenesis, which requires extracellular calcium, was markedly depressed by TMB-8, although enhanced cyclic AMP formation is only slightly depressed by this drug. Adrenal cortical microsomes possess an ATP-dependent 45calcium (45Ca2+) uptake system which responded to EGTA with a rapid efflux of 45Ca2+; EGTA-induced calcium efflux from this microsomal fraction was markedly reduced by a concentration of TMB-8 that blocked dibutyryl cyclic AMP-evoked steroidogenesis. TMB-8 produced a smaller but significant reduction of EGTA-facilitated 45Ca2+ efflux from a mitochondrial-enriched fraction. We interpret these results to mean that TMB-8 blocks the steroidogenic effect of dibutyryl cyclic AMP by interfering with the mobilization of a cellular pool of calcium that is probably localized to the endoplasmic reticulum. The physiological implications of these findings in relation to the complex interactions between calcium and cyclic AMP in adrenal steroidogenesis are discussed.

Adrenal Cortex↗
PubMed1982

Effect of angiotensin ii and norepinephrine on release of prostaglandins E2 and I2 by the perfused rat mesenteric artery.

Prostaglandin E2 (PGE2) and 6 keto-PGF1 alpha, the stable metabolite of prostacyclin (PGI2), have been measured in the effluent of perfused rat mesenteric arteries by the use of a sensitive and specific radioimmunoassay (RIA) method. The PGE2 and 6 keto-PGF1 alpha were continuously released by the unstimulated mesenteric artery over a period of 145 min. After 100 min of perfusion the release of PGE2 and 6 keto-PGF1 alpha was 45.1 +/- 8.4 pg/min and 254 +/- 75 pg/min respectively, which is in accord with the general belief that PGI2 is the major PG synthesized by arterial tissue. Angiotensin II (AII) (5 ng/ml) induced an increase of PGE2 and 6 keto-PGF1 alpha release without changing the perfusion pressure. The effect of norepinephrine (NE) injections on release of PGs depended on the duration of the stabilization period. The changes of perfusion pressure induced by NE were not related to changes in release of PGs. Thus, it seems that the increase of PG release induced by AII and NE was due to a direct effect of the drugs on the vascular wall. This may represent an important modulating mechanism in the regulation of vascular tone.

6-Ketoprostaglandin F1 alpha↗