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Biomedical subjects

G Romero

Publications and source records attributed to G Romero.

At least 19 recordsLinked to original sources
PubMed1992

The generation of inositolglycan mediators from rat liver plasma membranes: the role of guanine nucleotide binding proteins.

The guanine nucleotide dependence for the generation of inositolglycan second messengers from rat liver plasma membranes has been investigated. Plasma membranes, when treated with insulin release a soluble mediator substance which activates pyruvate dehydrogenase (PDH). Guanosine 5'-[3-thio]triphosphate (GTP gamma S) was found to be as potent as insulin in stimulating mediator release. The stimulatory effects of GTP gamma S required the presence of magnesium and following preincubation of membranes with guanosine 5'-[2-thio]diphosphate (GDP beta S) the stimulation of mediator release by either insulin or GTP gamma S was blocked. The activation of PDH by mediator fractions produced in response to either insulin or GTP gamma S was abolished following treatment of the fractions with anti-inositolglycan antibodies. The significance of these observations with respect to the possible involvement of a regulatory guanine-nucleotide binding protein (G-protein) in the generation of insulin mediators is discussed.

Adenosine Triphosphate↗
PubMed1992

Effect of prenatal exposure to tianeptine on different neurotransmitter receptors and 5-HT-stimulated inositol phosphate formation in rat brain.

Tianeptine, an antidepressant drug enhancing 5-HT uptake, was given to pregnant rats in the last 15 days of gestation and different neurotransmitter receptors as well as 5-HT2 receptor-linked inositol phosphate formation were measured in the brains of the offspring. Prenatal exposure to tianeptine significantly decreased the density of 3H-imipramine binding sites in the cerebral cortex of the pups without affecting beta-adrenoceptors, serotonin 5-HT2 and 5-HT1B receptors or inositol phosphate formation after a 5-HT challenge. Striatal dopamine D2 receptors labelled with 3H-spiroperidol were not changed but an apparent increase in the affinity of dopamine was noticed in the pups prenatally exposed to the drug. The results show that the neurochemical profile of tianeptine markedly differs from that of most antidepressants.

Animals↗
PubMed1992

Dextran administration avoids hemodynamic changes following paracentesis in cirrhotic patients. A safe and inexpensive option.

Paracentesis associated with albumin administration has been shown to be a safe and useful procedure in the treatment of patients with cirrhosis and ascites. Given the high cost of albumin, 20 patients with cirrhosis and ascites were treated in an open study, with daily paracentesis using dextran 70, an inexpensive volume expander, instead of albumin. In the first 10 patients, hemodynamic evaluation was performed in basal conditions, after each paracentesis (5 liter), and after dextran infusion. Twelve hours after each paracentesis without expansion, a significant drop in pulmonary capillary wedge pressure from 9.5 +/- 1.0 to 7.1 +/- 1.7 (P less than 0.01) and a reduction in cardiac output from 6.6 +/- 1.0 to 5.0 +/- 1.9 (NS) were observed. Moreover, the hematocrit rose significantly from 36.8 +/- 5.6 to 39.2 +/- 4.8 (P less than 0.01). These parameters returned to baseline values after the administration of 84 +/- 14 ml of dextran 70 for each 1000 ml of ascites removed. The other 10 patients received dextran 70 simultaneously with the paracentesis without hemodynamic control. No significant changes in renal and hepatic functions were observed at the end of the study. The mean volume of ascites removed was 12.3 +/- 4.6 liter. Two patients developed hyponatremia that required no treatment. No patient developed renal failure. One patient died because of gastrointestinal bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Role of the glycosylphosphatidylinositol/inositol phosphoglycan system in human fibroblast proliferation.

The involvement of the glycosylphosphatidylinositol/inositol phosphoglycan (gly-PtdIns/IPG) system in the stimulation of macromolecular syntheses in human fibroblasts has been investigated. The study demonstrates that an insulin sensitive gly-PtdIns/IPG system is present in human fibroblasts, that IPG can significantly stimulate DNA, RNA, and protein synthesis, and that the action of insulin on DNA synthesis as well as that of IPG can be significantly reduced by a specific anti-IPG antibody. These results strongly support the hypothesis that the gly-PtdIns/IPG system is involved in the signal transduction pathway leading to the stimulation of cell proliferation.

Cell Division↗
PubMed1992

Widespread dermatophytosis due to Microsporum (Trichophyton) gallinae in a patient with AIDS--a case report from Spain.

We report the case of a 25-year-old, HIV-positive patient (group IV, A, C2 clinical stage) with a widespread dermatophyte infection. He was a male gypsy with a known history of intravenous drug abuse. After an episode of cerebral toxoplasmosis for which he was treated with systemic steroids (because of cerebral oedema) he developed, over 16 days, a remarkably extensive ringworm of the trunk due to an unusual zoophilic dermatophyte, Microsporum (Trichophyton) gallinae. Human infection with this dermatophyte species is unusual: there are as few as seven proven reported cases, all of whom had localized lesions. This is the first widespread and severe case reported in man and also the first reported from Spain.

AIDS-Related Opportunistic Infections↗
PubMed1991

Glycosyl-phosphatidylinositol/inositol phosphoglycan: a signaling system for the low-affinity nerve growth factor receptor.

Nerve growth factor (NGF) exerts a variety of actions during embryonic development. At the early stages of inner ear development, NGF stimulates cell proliferation, an effect mediated through low-affinity receptors. We have studied the possibility that the glycosyl-phosphatidylinositol/inositol phosphoglycan (glycosyl-PtdIns/IPG) system is involved in transmitting this NGF signal. Endogenous glycosyl-PtdIns was characterized in extracts of cochleovestibular ganglia (CVGs) that incorporated [3H]glucosamine, [3H]galactose, [3H]myristic acid, and [3H]palmitic acid. Incubation of CVG with NGF produced a rapid and transient hydrolysis of glycosyl-PtdIns. Hydrolysis was complete at 100 ng/ml, and the half-maximal effect occurred at 25 ng/ml, overlapping with the concentration dependence of the mitogenic effect of NGF. An IPG was isolated from embryonic extracts. It had biological effects similar to those reported for the insulin-induced IPG in other tissues. It exerted a powerful mitogenic effect on CVG, comparable to that of NGF. Both the IPG- and NGF-induced cell proliferation were blocked by anti-IPG antibodies that recognized the endogenous IPG on a silica plate immunoassay. These results show that CVG possesses a fully active glycosyl-PtdIns/IPG signal transduction system and that the proliferative effects associated with NGF binding to low-affinity receptors require IPG generation.

Animals↗
PubMed1991

Mechanism of phospholipase C-induced release of EDRF from pulmonary artery endothelium.

The mechanism of phospholipase (PL) C-induced release of endothelium-derived relaxing factor (EDRF) was investigated. Bovine pulmonary artery endothelial cells (BPAEC) were treated with phosphatidylinositol (PI)-selective PLCs, nonselective PLCs, or a nonselective PLD. PI-PLCs elicited PI-glycan anchor hydrolysis but did not alter either intracellular Ca2+ ([Ca2+]i) in fura-2-loaded BPAEC or EDRF production in BPAEC-vascular smooth muscle cocultures. In contrast, non-selective PLCs increased [Ca2+]i, an effect prevented by prior exposure to the PLCs, and EDRF production in a time- and concentration-dependent manner. Antibodies raised against PI-glycan anchors did not alter, while heat denaturation abolished, the PLC-dependent effects. Removal of extracellular Ca2+ with [ethylene-bis(oxyethylenenitrilo)]tetraacetic acid both prevented and reversed PLC-stimulated increases in [Ca2+]i and inhibited EDRF production. Although Mn2+ quenched PLC-induced increases in fura-2 fluorescence, high PLC concentrations elicited significant dye loss from fura-2-loaded BPAEC. We conclude that the effects of exogenous PLC on EDRF production are not dependent on release of a membrane PI-glycan-linked moiety. Rather, the PLC actions are mediated by a graded increase in cell membrane permeability, probably related to pore formation by the hemolytic activity of the enzyme, followed by an influx of extracellular Ca2+.

Animals↗
PubMed1991

Insulin mediators are the signal transduction system responsible for insulin's actions on human placental steroidogenesis.

To test the hypothesis that insulin mediators serve as the signal transduction system for insulin's steroidogenic actions in human placental cytotrophoblasts, we examined the effects of two inositolglycan insulin mediators, the insulin pH 2.0 chiro-inositol mediator (IM-pH 2.0) and the insulin pH 1.3 myo-inositol mediator (IM-pH 1.3), on cytotrophoblastic steroidogenesis. When human cytotrophoblasts were incubated in medium supplemented with androstenedione for 24 h, treatment with IM-pH 2.0 or IM-pH 1.3 suppressed aromatase activity by 15% (P less than 0.05) and 49% (P less than 0.05), respectively, compared to insulin, which suppressed aromatase activity by 21% (P less than 0.05). When cytotrophoblasts were incubated in medium supplemented with pregnenolone for 24 h, treatment with IM-pH 2.0 or IM-pH 1.3 stimulated 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity by 145% (P less than 0.05) and 168% (P less than 0.05), respectively, compared to insulin, which stimulated 3 beta HSD activity by 63% (P less than 0.05). Suppression of aromatase activity and stimulation of 3 beta HSD activity by inositolglycan mediators were both concentration dependent. Moreover, preincubation of cytotrophoblasts with the antiinositolglycan antibody alpha IGP completely abolished insulin's ability to either inhibit aromatase or stimulate 3 beta HSD activity. These results indicate that insulin mediators mimic insulin's effects on cytotrophoblastic aromatase and 3 beta HSD activities and suggest that inositolglycan mediators are the signal transduction mechanism responsible for insulin's regulation of human placental steroid hormone biosynthesis.

3-Hydroxysteroid Dehydrogenases↗
PubMed1991

[Primary risk of hemorrhage due to esophageal varices in cirrhotic patients: significance of the associated endoscopic signs and hepatic functional reserve].

Significance of endoscopic findings associated to esophageal varices (Japanese Research Society for Portal Hypertension) and hepatic dysfunction (Child-Pough classification) as predictive factors of variceal bleeding in cirrhotic patients is analyzed. In a cooperative prospective experience 137 cirrhotic patients with esophageal varices were examined in the period May 1987/89: 83 out of them had never bled from their varices (VENS group) while 54 recently had (VES group). A highly significative association was found between variceal size over 3 mm (grade II-III) and bleeding: 96.3% vs. 34.9% in VENS group (p = 0.01); similar association was found with regard to endoscopic detection of "red signs": 92.6% in bleeding group vs. 20.5% in VENS one (p = 0.01). "Red signs" were found on grade II-III varices in 98.5% of cases, and this association were related to variceal bleeding in 75.5%. Hepatic dysfunction was not directly related to bleeding episodes but "red signs" endoscopic detection in VENS group increased with liver function deterioration: 9.1% in Child A class, 27.3% in Child B, and 41.2% in Child C (p = 0.01). The strong association founded between bleeding and both grade II-III variceal size and "red signs" detection, suggest the possibility to identify a high risk group of cirrhotic patients candidate to prophylactic methodologies.

Adult↗
PubMed1990

A pertussis toxin-sensitive G-protein mediates some aspects of insulin action in BC3H-1 murine myocytes.

The involvement of G-proteins in the insulin signal transduction system has been studied in detail using the murine BC3H-1 myocyte system. Pertussis toxin (PT) treatment, previously shown to attenuate some of the metabolic effects of insulin in this cell line (Luttrell, L.M., Hewlett, E.L., Romero, G., and Rogol, A.D. (1988) J. Biol. Chem. 263, 6134-6141), abolished insulin-induced generation of diacylglycerol and inositolglycan mediators with no effects on either the autophosphorylation of the insulin receptor or the phosphorylation of the major endogenous substrates for insulin-stimulated tyrosine kinase activity (pp185 and pp42-45). In vitro ADP-ribosylation and immunoblotting studies suggest that the major PT substrate is a 40-kDa protein of the G alpha family. This protein band did not exhibit detectable tyrosine phosphorylation upon stimulation of either intact cells or cell membranes with insulin. In the presence of low concentrations of GTP, insulin treatment of isolated myocyte plasma membranes resulted in a small (30-40%) but significant stimulation of GTP hydrolysis. This effect was best observed in the presence of small concentrations of sodium dodecyl sulfate. The rate of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) binding to BC3H-1 membranes was also significantly increased in the presence of insulin. The effects of insulin on GTP hydrolysis and GTP gamma S binding were found to be dependent on the concentration of insulin. These effects were not detected in plasma membranes prepared from PT-pretreated BC3H-1 myocytes. In contrast, pretreatment with the B (inactive) subunit of PT did not alter the response of myocyte membranes to insulin. High affinity binding of [125I]iodoinsulin to myocyte plasma membranes was reduced by 60-70% in the presence of guanine nucleotides. Similar effects on insulin binding were produced by PT pretreatment of the cells. In contrast, adenine nucleotides had no effect on insulin binding. Scatchard analysis of the binding data showed that the observed effects of guanine nucleotides and PT on insulin binding resulted either from a reduction in the number of high affinity insulin binding sites or from a significant reduction of the affinity of insulin for its receptor. Low affinity binding sites did not appear to be affected by either guanine nucleotides nor PT pretreatment. These results provide substantial evidence suggestive of a noncovalent interaction between the insulin receptor and a regulatory G-protein system during the process of insulin signaling.

Animals↗
PubMed1979

Inhibitory activity of alpha 1-antitrypsin in infants with idiopathic respiratory distress syndrome.

In two groups of neonates serum concentrations of alpha-1-antitrypsin (1-AT) were determined by means of radial immunodiffusion, and 1-AT inhibitory capacity determinations were made using benzoyl-1-arginine-p-nitroanilide as a substrate. There were 66 children in the first group of neonates with idiopathic respiratory distress syndrome (IRDS), and 82 healthy children in the second group with birth weight and gestational and post natal ages similar to those of neonates with IRDS. In the latter, 1-AT concentration and inhibitory activity levels were lower than those found in healthy children; these differences were statistically significant. These findings explain both the retardation in the lysis of the hyaline membrane and the fact that a decrease in serum 1-AT levels elicits lung tissue damage by the action of proteolytic enzymes contained in leucocytes.

Birth Weight↗
PubMed1977

[Pharmacodynamics of alcoholic and aqueous extracts from the Casimiroa edulis seed].

The hypnotic properties of leaves and seed of Casimiroa edulis (zapote blanco) a tropical fruit, are well known. In the present investigation, pharmacological studies on aqueous and alcoholic extracts were carried out in dogs, cats, rabbits and guinea pigs, using different experimental models. The action of the extracts upon blood pressure, cardiac activity, respiration rate, muscular tone, electroencephalographic activity, sleep and other parameters were studied too. In addition to, studies upon isolated human, cat, rabbit and guinea pig tissues gave information about the extracts effect on smooth muscle activity. It was found that both aqueous and alcoholic extract of the seed of zapote blanco produced marked hypotension in all animal species, which was followed by a sleep-like stage. Also a definitive oxitocic effect in vivo and in vitro was demonstrated suggesting the presence of a potent uterus constricting substance.

Animals↗
PubMed1976

Ambient temperature of hypoxia: a differential study of liver catalase and cytochrome oxidase in guinea pig.

The activities of liver catalase and cytochrome oxidase have been determined in sea-level and high-altitude native guinea pigs exposed to different ambient temperatures. The activities of both of these enzymatic systems have been found to increase as ambient temperature is reduced, and this occurs in the sea-level and the high-altitude animals. At equal temperatures, cytochrome oxidase activity is identical in the liver of guinea pigs from sea-level and high-altitude. Catalase activity is approximately 50% lower in the high-altitude animals than in the sea-level ones maintained at the same ambient temperature. It is necessary to reassess current data on hypoxia-induced enzymatic and hormonal changes measured under conditions where the ambient temperature was not controlled, especially in those cases involving volunteer human subjects.

Altitude↗
PubMed1976

Human semen ribonuclease. Location, properties and inhibition by sodium dodecyl sulfate, zinc sulfate and EDTA.

Optimal conditions were established for RNase activity measurement. The enzyme was measured in human seminal plasma as well as in spermatozoa. Results suggest that sperm enzyme may come from seminal plasma contamination and that RNase may be used as a marker enzyme for seminal plasma contamination. Sodium dodecylsulfate, a reagent utilized to produce the solubilization of the spermatozoa, produced a very strong inhibition of the RNase at low concentrations (530 muM). Zinc sulfate and EDTA also produced inhibition of the RNase activity. Such inhibition may be very useful in future studies of RNA metabolism in human spermatozoa.

Dithiothreitol↗