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Biomedical subjects

M Gimeno

Publications and source records attributed to M Gimeno.

At least 55 records · Page 3Linked to original sources
PubMed1994

Role of nitric oxide in eicosanoid synthesis and uterine motility in estrogen-treated rat uteri.

Cholinergic stimulation of vascular endothelin activates NO synthase (NOS), leading to generation of NO from arginine. This NO diffuses to the overlying vascular smooth muscle and causes vasodilatation. NOS has also been found in the central and peripheral nervous systems and it is clear now that NO plays an important role as a neurotransmitter. Here we investigate the role of NO in controlling contraction of uterine smooth muscle. Our previous work showed that NO activates the cyclooxygenase enzyme in the hypothalamus, leading to production of prostaglandin E2 (PGE2). We began by determining whether NO was involved in production of arachidonic acid metabolites in the uterus. Uteri were removed from female rats that had been treated with estrogen (17 beta-estradiol). Control animals were similarly injected with diluent. Tissues were incubated in vitro in the presence of [14C]arachidonic acid for 60 min. Synthesis of PGs and thromboxane B2 (TXB2) was markedly stimulated by sodium nitroprusside (NP), the releaser of NO. The effect was greatest on TXB2; there were no significant differences in increases of different PGs. The response to NP was completely prevented by Hb, a scavenger of NO. The inhibitor of NOS, NG-monomethyl-L-arginine (NMMA), significantly decreased synthesis of PGE2 but not the other prostanoids (6-keto-PGF1 alpha and PGF2 alpha). Addition of Hb to scavenge the spontaneously released NO inhibited synthesis of 6-keto-PGF1 alpha, PGE2, and PGF2 alpha, but not TXB2. There was a much lesser effect on products of lipoxygenase, such that only 5-hydroxy-5,8,11,14-eicosatetraenoic acid (5-HETE) synthesis was increased by NP, an effect that was blocked by Hb; there was no effect of NMMA or Hb on basal production of 5-HETE. Thus, NO stimulates release of the various prostanoids and 5-HETE; blockade of NOS blocked only PGE2 release, whereas Hb to scavenge the NO released also blocked synthesis of 6-keto-PFG1 alpha, PGE2, and PGF2 alpha, indicating that basal NO release is involved in synthesis of all these PGs, especially PGE2. Presumably, NMMA did not block NOS completely, whereas Hb completely removed released NO. This may explain the different responses of the various prostanoids to NMMA and Hb. To determine the role of these prostanoids and NO in control of spontaneous in vitro uterine contractility in the estrogen-treated uterus, the effect of blocking NOS with NMMA and of scavenging NO produced by Hb on the time course of spontaneous uterine contractility was studied. Surprisingly, blockade of NOS or removal of NO by Hb prevented the spontaneous decline in uterine motility that occurs over 40 min of incubation. We interpret this to mean that NO was released in the preparation and activated guanylate cyclase in the smooth muscle, resulting in production of cGMP, which reduces motility and induces relaxation. When the motility had declined to minimal levels, the effect of increased NO provided by NP was evaluated; apparently by stimulating the release of prostanoids, a rapid increase in motility that persisted for 10 min was produced. This effect was completely blocked by Hb. The action of NO was also blocked by indomethacin, indicating that it was acting via release of PGs. Apparently, when motility is low, activation of PG synthesis by NO to activate the cyclooxygenase enzyme causes a rapid induction of contraction, whereas, when motility is declining, NO acts primarily via guanylate cyclase to activate cGMP release; the action of the prostanoids released at this time is in some manner blocked.

Animals↗
PubMed1994

The role of cyclic nucleotides in the action of peripheral-type benzodiazepine receptor ligands in rat aorta.

1. Peripheral-type benzodiazepine ligands (Ro 5-4864, AHN-086, PK 11195 and PK 14105) inhibit, in a concentration-dependent and non-competitive manner, noradrenaline-induced contractions in isolated rat aortic rings (IC50 values: 24 +/- 1.8, 49 +/- 2.5, 15 +/- 1.2, 49 +/- 3.2 microM, respectively). 2. This effect is probably not mediated by peripheral-type benzodiazepine receptors and is not related to the presence of endothelium. 3. All compounds inhibited phosphodiesterase activity in vitro. 4. From the results obtained with nucleotide analogs, calcium antagonists and specific inhibitors of PDE isoenzymes, it can be concluded that the actions of AHN-086 and PK 11195 are related to effects on PDE I, III and IV.

Animals↗
PubMed1994

Liver lipoxygenase arachidonic acid metabolites in streptozotocin-induced diabetes in rats.

We have studied the liver 15-hydroxyeicosatetraenoic acid (15-HETE) and leukotriene B4 (LTB4) levels in streptozotocin- (ST)-induced diabetes in rats using liquid chromatography and radioimmunological techniques. Diabetic rats showed significant alterations of liver lipoxygenase metabolites when compared to controls. These 15-HETE and LTB4 increases were concomitant with raised levels of plasma and tissue thromboxane B2 (TXB2) and also urinary 2,3-dinor-TXB2 in plasma and urine, respectively. These changes confirm an activation of 5- and 15-lipoxygenase in the liver 3 days after i.p. ST administration.

Animals↗
PubMed1994

Blockade by interleukin-1-alpha of nitricoxidergic control of luteinizing hormone-releasing hormone release in vivo and in vitro.

Nitric oxide (NO) synthase (NOS), the enzyme that converts arginine into citrulline plus NO, the latter a highly active free radical, occurs in a large number of neurons in the brain, including certain neurons in the hypothalamus. Our previous experiments have shown that norepinephrine (NE)-induced prostaglandin E2 (PGE2) release from medial basal hypothalamic explants (MBH) is mediated by NO. Because release of luteinizing hormone (LH)-releasing hormone (LHRH) is also driven by NE and PGE2, we hypothesized that NO controls pulsatile release of LHRH in vivo, which in turn induces pulsatile LH release. Indeed, in vivo and in vitro experiments using an inhibitor of NOS (NG-monomethyl-L-arginine; NMMA) demonstrated that pulsatile LH release is mediated by NO; LHRH release in vitro is also mediated by this free radical. Cytokines that are released from cells of the immune system during infection also inhibit LHRH release. We compared the action of one such cytokine, interleukin-1 alpha (IL-1 alpha), on LHRH release with that of substances which inhibit or induce NO release. Microinjection of IL-1 alpha (0.06 pmol in 2 microliters) into the third cerebral ventricle (3V) of conscious, castrated male rats had an action similar to that of 3V microinjection of NMMA (1 mg in 5 microliters): it blocked pulsatile LH, but not follicle-stimulating hormone (FSH) release. The only difference between the responses to NMMA and IL-1 alpha was that the latency to onset was greater with IL-1 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Middle lobe syndrome].

Middle lobe syndrome (MLS) or atelectasis syndrome can affect any pulmonary lobe but occurs more frequently in the right middle lobe. Only 15 per cent of the reported cases are children. We report two cases of MLS in two boys of 4 and 12 years of age who were referred to our institution because they had suffered from recurrent pneumonies of the right middle lobe for ten months and six years respectively. We performed chest radiographs, computed tomography scanning, ventilation-perfusion scintigraphy and flexible bronchoscopy. The evolution in both cases to an atelectasic middle lobe with pulmonary shrinkage and lack of perfusion was the indication to lobectomy. Histological examination showed a bronchial obstructive process in the young patient and a chronic non specific inflammation of the pulmonary parenchyma in both. The resection brought about a cure. The identification of MLS is usually a late diagnosis. Thus, if atelectasis persists after an adequate medical therapy, resection of the lobe is indicated.

Child↗
PubMed1993

Role of nitric oxide in the control of luteinizing hormone-releasing hormone release in vivo and in vitro.

Nitric oxide (NO) synthase, the enzyme which converts arginine into citrulline plus NO, a highly active free radical, has been found in many neurons in the brain, including neurons in the hypothalamus. Our previous experiments showed that norepinephrine-induced prostaglandin E2 release from hypothalamic explants incubated in vitro is mediated by NO. Since the release of luteinizing hormone-releasing hormone (LHRH) is also driven by norepinephrine and prostaglandin E2, we hypothesized that NO might also control pulsatile release of LHRH in vivo, resulting in turn in pulsatile release of luteinizing hormone (LH). To ascertain the role of NO in control of pulsatile LH release in vivo, an inhibitor of NO synthase, NG-monomethyl-L-arginine (NMMA), was microinjected into the third cerebral ventricle (1 mg/5 microliters) of conscious castrate male rats at time 0 and 60 min later; blood samples were taken every 10 min during this period. NMMA blocked pulsatile LH release within 20 min, and plasma LH concentration declined further without pulses after the injection at 60 min. Pulsatile release of LH was not altered in diluent-injected controls. NMMA did not alter pulsatile release of follicle-stimulating hormone, which suggests that its release does not require NO. Incubation of medial basal hypothalami with norepinephrine (10 microM) induced an increase in LHRH release that was inhibited by NMMA (300 microM). NMMA alone did not alter basal LHRH release, whereas it was augmented by sodium nitroprusside (100 microM), which releases NO spontaneously. This augmentation was prevented by hemoglobin (2 micrograms/ml), which binds the NO released by nitroprusside. Our previous experiments showed that norepinephrine-induced release of prostaglandin E2 is mediated by NO. Nitric oxidergic neurons were visualized in the median eminence adjacent to the LHRH terminals. The combined in vivo and in vitro results indicate that the pulsatile release of LHRH induced by norepinephrine is brought about by alpha 1-adrenergic activation of NO synthase. NO then induces prostaglandin E2 release that activates exocytosis of LHRH secretory granules into the portal vessels to induce pulsatile LH release.

Amino Acid Oxidoreductases↗
PubMed1993

[Alloimmune neonatal neutropenia: flow cytometry study of the 1st patient described in Spain with identification of an anti-NA1].

A strong antibody was found in a mother (first pregnancy) who had a severe neutropenic baby. The father's granulocytes were typed by flow cytometry as NA1+, NA2+, NB1+, ND1+ and the mother as NA1-, NA2+, NB1+ and ND1+. The antibody was identified as anti-NA1 by us, and confirmed later by a reference laboratory. The serum reacted with 54.8% of the 31 donors tested. The same antibody was found in the child's serum 35 days after birth, and the reactivity was stronger than in the mother's serum. The HLA-DR, DQ from the mother was DR3, DR7; DR52, DR53; DQ2. The baby's granulocytes were recovered slowly over a four-month period, but the course was benign without any specific treatment. Five months after birth, with recovery, the child's serum became negative and his granulocytes were confirmed as NA1+. Due to the difficulties in fully diagnosing and working with granulocytes we suspect that there are undetected cases; only one case has been recorded in Spain before.

Female↗
PubMed1993

[Follow-up of the quantitative serological response to the treatment of Helicobacter pylori infection in children].

BACKGROUND: The aim of the present study was to know the usefulness of a enzyme immunoanalysis (EIA) technique for the monitorization of the serologic to treatment of infection by Helicobacter pylori in Spanish children. METHODS: 17 children with digestive symptomatology in whom the diagnosis of infection by Helicobacter pylori was confirmed and eradication was objectified following a month of treatment with amoxycillin, metronidazole and Bismuth subcitrate were studied. In each patient a biopsy of the gastric mucosa was performed and a sample of serum was withdrawn for initial diagnosis and for control of eradication once treatment had finished (mean time between diagnosis and confirmation of eradication was 79.6 +/- 33.5 days). The samples of gastric mucosa were processed by standard methodology (histologic and/or culture). Serologic determinations (IgG and IgA) were carried out using a EIA technique (Pyloriset EIA-G and EIA-A; Orion Diagnostica). RESULTS: In 12 of the 17 patients resolution of the clinical symptomatology was produced. A decrease in the levels of IgG was observed in 15 (88.2%) and of IgA in 14 (82.3%) of all the children studied. A significant difference was found between the mean values of the levels of IgG (p < 0.01) and IgA (p < 0.05) in the 17 patients at the time of diagnosis and following eradication. CONCLUSIONS: In agreement with the present results the series study of the quantitative level of antibodies IgG and IgA versus Helicobacter pylori is shown as an adequate instrument for evaluating the response to treatment in pediatric patients.

Adolescent↗
PubMed1992

Nitric oxide mediates norepinephrine-induced prostaglandin E2 release from the hypothalamus.

Nitric oxide (NO), formed by conversion of arginine to citrulline and NO by NO synthase, mediates relaxation of vascular smooth muscle. NO synthase has been demonstrated by immunocytochemical methods in neurons in various parts of the central nervous system including the hypothalamus. The latter finding suggested to us that NO might play a role in controlling the release of hypothalamic peptides. We have previously shown that norepinephrine mediates the release of luteinizing hormone-releasing hormone (LHRH) from LHRH terminals in the median eminence into the hypophyseal portal veins, which transport LHRH to the anterior pituitary gland to trigger release of luteinizing hormone from gonadotrophs. LHRH release from these terminals requires increased release of prostaglandin E2 (PGE2). PGE2 activates adenylate cyclase to produce cAMP, and then cAMP induces the exocytosis of LHRH secretory granules. In view of the evidence above and because of the developing evidence for the importance of NO in the central nervous system, it occurred to us that NO might be involved in this process. Consequently, we evaluated the role of NO in the release of PGE2 from medial basal hypothalamic fragments. As previously reported, norepinephrine (10 microM) increased PGE2 release from the hypothalamic fragments. The inhibitor of NO synthase NG-monomethyl-L-arginine (NMMA, 300 microM) blocked the stimulation of PGE2 release induced by norepinephrine but had no effect on the basal release of PGE2. Sodium nitroprusside (100 microM), which liberates NO, also elevated PGE2 release from the hypothalamic fragments. This elevation was not affected by NMMA, presumably because NMMA blocks enzymatic generation of NO but does not alter NO liberated by nitroprusside. When the NO liberated by nitroprusside was inactivated by hemoglobin (2 micrograms/ml), the effect of nitroprusside on PGE2 release was completely inhibited. Neither NMMA nor hemoglobin altered the basal release of PGE2, which indicates that NO is not responsible for basal PGE2 release. Addition of L-arginine (10 microM to 1 mM), the substrate for NO synthase, had no effect on basal PGE2 production. These results indicate that NO synthase is not activated in unstimulated hypothalamic fragments in vitro. The results suggest that norepinephrine activates NO synthase leading to the production of NO, which subsequently activates cyclooxygenase and results in the production of PGE2. PGE2 then activates adenylate cyclase leading to generation of increased cAMP, which induces exocytosis of secretory granules of LHRH and other neuropeptides released by PGE2. The indication that NO is essential to norepinephrine-induced release of PGE2 from hypothalamic fragments provides insight into the mechanism of LHRH release and the results open the possibility that the importance of NO to neuronal functions may be widespread in the nervous system.

Amino Acid Oxidoreductases↗
PubMed1992

Measurement of mechanical forces acting on the area pellucida of the early chick embryo.

We have designed a method for measuring mechanical forces acting on the area pellucida of the chick embryo between stages 1 to 5 of HAMBURGER and HAMILTON (1951). The coordinates of several points on the outline of the area pellucida were used as input, from which a computer program measured the changes in the position of similar points to produce a table of values which, we argue, reflect mechanical forces in the embryo. The results obtained are shown to be reproducible between embryos. The computer program and the measurements obtained were then used to predict the behaviour of surgical incisions made in the area pellucida, using the tables obtained from direct measurements of embryos and the coordinates of various points on the surface of the operated embryos. This procedure was applied to embryos cultured by the method of NEW (1955) and in-ovo. It was found that in those embryos cultured by EWS technique the computer predictions correspond very closely to shape measurements made directly from embryos. However, the correspondence is less close when applied to embryos in-ovo.

Animals↗
PubMed1992

Early in-vitro histological chondral differentiation.

In vitro chondrogenesis is possible in the chick embryo from stage 4 of Hamburger and Hamilton (1951), only 18-19 hours of incubation, before somite formation. In stage 4 of Hamburger and Hamilton (1951) the chondroblasts are placed laterally to the primitive streak and notochord cells are not necessary for cartilage differentiation.

Animals↗
PubMed1989

Hormonal regulation on bioactive aortic substance (BAS) production.

Rat's vessel wall releases a protein named BAS (Bioactive Aortic Substance) whose antiaggregating effect on platelets and inotropy vascular properties have been already described. In this work we have investigated the effects of pregnancy, gonadectomy and gonadectomy with hormonal treatment on the BAS production from rat aortic rings. BAS production in pregnancy and ovariectomized rats was markedly decreased compared to normal rats. Return to normal values was obtained after estradiol treatment in ovariectomized rats. Castration resulted in an increased of BAS production which was suppressed by testosterone treatment.

Animals↗
PubMed1989

[Incrusted alkaline cystitis. Physiopathological basis for treatment with acetohydroxamic acid].

Alkaline incrusting cystitis is an uncommon clinical condition that usually presents in the course of bladder disease. It has characteristic presenting features and is difficult to treat despite currently available therapeutic measures. Three such cases that had been diagnosed and treated at our department is described herein. The literature is reviewed and the pathologic mechanisms of this condition are analyzed.

Aged↗