Biomedical subjects

M Barrios

Publications and source records attributed to M Barrios.

At least 37 records · Page 2Linked to original sources

PubMed1999

Modulatory effect of nitric oxide on acetylcholine-induced activation of cat petrosal ganglion neurons in vitro.

The inhibitory effect of nitric oxide (NO) on carotid chemosensory responses to hypoxia has been attributed in part to an antidromic inhibition of chemoreceptor cells activity. However, NO may also modulate the activity of the primary sensory neurons because NO is produced in the soma of these neurons located in the petrosal ganglion. Since a population of petrosal neurons is selectively activated by acetylcholine (ACh), we studied the effects of NO-donor, sodium nitroprusside (SNP), and the NO-synthase inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME), on the responses evoked in the carotid sinus nerve (CSN) by ACh applied to the petrosal ganglion in vitro. ACh (1 microgram-1 mg) increased the frequency of action potentials recorded from the CSN in a dose-dependent manner. SNP (10-50 microM) reduced the sensibility and amplitude of the CSN response to ACh, although the maximal response appears less affected. The withdrawal of SNP from the superfusion medium increased the sensibility of the responses to ACh. l-NAME (1-2 mM) slightly increased the sensibility of the ACh-induced responses, effect that persisted after l-NAME withdrawal. These results suggest that NO may play a role as modulator in this autonomic primary sensory ganglion.

Acetylcholine↗

PubMed1999

Neuropsychological functioning in a subclinical obsessive-compulsive sample.

BACKGROUND: Previous neuropsychological research has suggested that the study of psychometrically defined subclinical samples might be a valid approach to understand the underlying pathophysiology of obsessive-compulsive disorder (OCD). This approach has the potential benefit of overcoming some of the methodological problems linked to the use of clinical samples. METHODS: A group of subclinical obsessive-compulsive (OC) subjects (n = 35), selected on the basis of their scores on the Padua Inventory, and a control group were assessed on executive functioning tasks and other neuropsychological tests which have been demonstrated to be impaired in clinical OCD patients and/or in those with several basal ganglia disorders. RESULTS: Subclinical OC subjects needed significantly more moves than controls to reach the solution criteria on the Tower of Hanoi puzzle, and performance on this test was positively correlated with total score and the Checking factor of the Padua Inventory. There were no between-group differences on the other frontal lobe tests. CONCLUSIONS: The results suggest that deficits in manipulating spatial information might be basic in OCD, and are congruent with the involvement of the frontostriatal circuits in the disorder.

Adult↗

PubMed1999

Reduced design fluency in subclinical obsessive-compulsive subjects.

This study examined the verbal and design fluency abilities of 25 subclinical obsessive-compulsive (OC) subjects and 27 noncompulsive control subjects. As hypothesized, the OC group showed reduced design fluency, and design fluency was also negatively correlated with obsessionality. These results provide further evidence for the involvement of the right corticostriatal systems in the mediation of OC behaviors, extending the findings to individuals with subclinical symptoms.

Adult↗

PubMed1999

[Neutralization of the hemorrhagic effect induced by Bothrops asper (Serpentes: Viperidae) venom with tropical plant extracts].

Organic extracts representing 48 species included in 30 families of Costa Rican tropical plants were evaluated for their ability to neutralize hemorrhagic activity induced by the venom of the snake Bothrops asper. A bioassay in mice was used, based on intradermal injection of either venom or venom-extract mixtures followed by the measurement of hemorrhagic areas. Total inhibition of hemorrhage was observed with the ethanolic, ethyl acetate and aqueous extracts of Bursera simaruba, Clusia torresii, C. palmana, Croton draco, Persea americana, Phoebe brenesii, Pimenta dioica, Sapindus saponaria, Smilax cuculmeca and Virola koschnyi. Chemical analysis of these extracts identified catequines, flavones, anthocyanines and condensated tannins, which may be responsible for the inhibitory effect observed, probably owing to the chelation of the zinc required for the catalytic activity of venom's hemorrhagic metalloproteinases.

Animals↗

PubMed1998

Infection of rabbits with R29 strain of bovine immunodeficiency virus: virulence, immunosuppression, and progressive mesenteric lymphadenopathy.

To assess the value of bovine immunodeficiency virus (BIV) infection as a model for human immunodeficiency virus (HIV) infection in man, we studied the impairment of certain immunologic functions in New Zealand white rabbits experimentally infected with an uncloned virulent isolate of the virus, BIV R29. Serum samples were tested by Western blot for the presence and persistence of antibody production. The T- and B-lymphocyte function was studied by evaluation of the blastogenic responsiveness to concanavalin A (Con A) and to dextran sulfate (DxS). All infected rabbits seroconverted to BIV antigens within 2 to 4 weeks postinfection (p.i.) The BIV was isolated from the peripheral blood lymphocytes (PBLs) of 13 of 17 rabbits (77%) early in the infection and also from 5 of 17 hyperplastic mesenteric lymph nodes (29%) and 10 of 17 spleens (59%) during the chronic stage of infection. Seven of 17 BIV-infected rabbits (41%) developed marked immunodepression 2 to 5 months p.i., and later, 5 exhibited a rapidly progressive disease with anorexia, weight loss, neurologic impairment, splenomegaly, and mesenteric lymphadenopathy. These data underline the value of the BIV model for studying HIV pathogenesis in vivo and the development of interventional strategies for AIDS.

Animals↗

PubMed1998

An in vivo model to study the anti-malaric capacity of plant extracts.

An in vivo model to study the antimalaric effect of plant extracts is described. White mice (25-30 g body weight) are treated subcutaneously with 0.6 ml of the diluted extract starting seven days before P. berghei infection; treatment continues until death or for 30 days. Simultaneously 0.2 ml of the extract are applied per os starting three days before infection. In a test of the model, treated and non-treated animals differed in body weight, survival time, haematocrite, parasitemia development, and spleen or liver weight of recent dead or killed mice.

Animals↗

PubMed1998

[Memory in multiple sclerosis: review of performance and relationship with clinical variables and neuroimaging].

INTRODUCTION: Neuropsychological studies in multiple sclerosis (MS) mainly have centred on the study of memory disorder. DEVELOPMENT: The prevalence of memory deficits in MS population is around 40-60%. These deficits could be sum up in an impaired immediate memory, a learning capacity lower than normal controls subjects and a worse long term memory. The results of the reviewed studies about the relationship between performance in memory tasks and clinical variables, show that physical disability and depressive symptoms do not influence this performance. Whilst, years of evolution and, mainly, disease course are related to a worse performance in memory tasks. In structural neuroimaging studies (CT and MRI) it is considered that ventricular dilatation and the total lesion load are predictor variables of MS patients performance in different memory tasks. CONCLUSION: This paper reviews several studies relative to amnesic function in subjects suffering from MS, emphasizing the most relevant contributions of the present neuropsychological literature.

Brain↗

PubMed1997

Hemispheric functional imbalance in a sub-clinical obsessive-compulsive sample assessed by the Continuous Performance Test, Identical Pairs version.

Obsessive-compulsive disorder (OCD) sufferers have long been observed to give excessive consideration to normally ignored exogenous and endogenous stimuli. This over-focused attention concerning their symptoms has led researchers to experimentally investigate the attentional mechanisms involved in this disorder and its psychobiological basis. Previous psychometric and neuropsychological research has demonstrated the validity of the sub-clinical analogue in the study of the mechanisms underlying OCD. In this study, 71 introductory university students were recruited from an original pool of 450 people on the basis of their scores on the Spanish version of the Padua Inventory. A high obsessive group (n = 35) was compared with a control group (n = 36) on a standard sustained attention task: the Continuous Performance Test, Identical Pairs version (CPT-IP). The results showed a significant interaction effect between CPT-IP subscales (verbal and spatial) and group membership. This effect was more evident among men. The results were unrelated to general intelligence, depression, anxiety, personality or motivational factors. These findings support the hypothesis that neuropsychological deficits in OCD may be related to a hemispheric functional imbalance rather than to a lateralised dysfunction of a particular hemisphere.

Adolescent↗

PubMed1997

Involvement of calcium in the cardiac depressant actions of a garlic dialysate.

In order to elucidate a possible role for calcium on the negative cardiotropic effects of a garlic (Allium sativum L., Liliaceae) dialysate in rat atria we studied: (a) the effects of our extract 15 min after preincubation with high and low concentrations of extracellular calcium ([Ca2+]o) on left and right activity of rat atria. The negative inotropism of garlic dialysate increased with calcium 0.75 mM; in contrast, high level of calcium (4.5 mM) induced a significant reduction of this depressant effect. None of these treatments modified the negative chronotropism of garlic; (b) nifedipine (10(-9) to 10(-7) M, verapamil (10(-9) to 10(-7) M) and diltiazem (10(-9) to 10(-7) M) induced a concentration-dependent synergism of the log concentration-effect of garlic dialysate on left atria. Verapamil and diltiazem (10(-7)M), but not nifedipine increased the inhibitory chronotropism of garlic in right atria; (c) negative inotropic and chronotropic effects demonstrated by nifedipine (1 x 10(-10) to 1.1 x 10(-6) M) were antagonized as expected by preincubation with Bay K-8644. Depressant actions of garlic were not modified with this pretreatment. These results suggest that the negative inotropic effect of our garlic dialysate is related to [Ca2+]o availability. It is possible that a restriction of intracellular calcium contributes to this effect. However, the negative chronotropic effect of garlic is scarcely affected by these modifications.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1997

In vitro suppression of HIV-1 replication by ajoene [(e)-(z)-4,5,9-trithiadodeca-1,6,11-triene-9 oxide].

Studies were performed to establish whether synthetic ajoene exhibited differential inhibitory activity against human immunodeficiency virus (HIV)-1 (IIIB) and to clarify the mechanism of its antiviral effects. Our results demonstrate that ajoene protected acutely infected Molt-4 cells against HIV-1 and blocked further destruction of CD4 T-cells in vitro. Ajoene showed dose-dependent inhibition, with 50% cytotoxic concentration (CTC50%) and 50% effective inhibitory concentration (EIC50%) values of 1.88 microM and about 0.35 microM, respectively, when the test compound was added before or after HIV-1 infection and incubation carried out at 37 degrees C for 4 days. Ajoene proved relatively more active than dextran sulfate in blocking HIV-1 virus-cell attachment. The mode of anti-HIV action of ajoene can be ascribed to the inhibition of early events of viral replication, particularly virus adsorption.

Adsorption↗

PubMed1996

Developmental changes in glutamate receptor-activated translocation of protein kinase C in cerebellar granule neurons.

Developmental changes in glutamate receptor agonist-produced enhancement of 4-beta-[3H]phorbol-12,13-dibutyrate binding ([3H]-PDBu binding), indicative of an intracellular translocation of protein kinase C (PKC), were investigated in cerebellar granule cells. Our observations demonstrate that the magnitude of glutamate-, NMDA-, and kainate-produced enhancement of PKC translocation was dramatically decreased between 2 and 12 DIV, whereas there was only a minor reduction in the corresponding response caused by the non-NMDA receptor agonist, AMPA. The maximally enhanced stimulation of PKC translocation caused by glutamate and NMDA was significantly reduced already at 4 DIV, whereas a significant reduction of the kainate-induced enhancement of [3H]PDBu binding was not observed until 8 DIV. Glutamate- and NMDA-induced responses were effectively blocked by the specific NMDA receptor antagonists MK-801 (1 microM) and APV (100 microM) as well as by the addition of Mg2+ into assay media. In contrast, the non-NMDA receptor antagonist, CNQX (10 microM), effectively blocked the kainate-induced enhancement of [3H]PDBu binding, but had no effect on the NMDA- and glutamate-induced stimulation of PKC translocation. The metabotropic glutamate receptor agonist, ACPD (up to 250 microM), had no effect on the translocation of PKC. Taken together, our data support the working hypothesis that the rapidly occurring changes in the glutamate receptor agonist-produced translocation of PKC are most likely due to a differential maturation of glutamate ionotropic receptor subtypes and/or to development-dependent alterations in mechanisms responsible for the coupling between the glutamate receptor subtypes and the activation of PKC translocation in cerebellar granule neurons.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1996

Effects of K+ channel blockers and openers on antinociception induced by agonists of 5-HT1A receptors.

The modulation by K+ channel-acting drugs of the antinociceptive effect of several 5-HT1A receptor agonists was examined with the hot plate test in mice. All the 5-HT1A receptor agonists tested induced dose-dependent antinociception, the order of potency being (+/-)-8-hydroxy-2-(di-n-propyl-amino)tetralin (8-OH-DPAT) > buspirone > or = lesopitron > or = tandospirone. The blockers of ATP-sensitive K+ channels (KATP) gliquidone and glipizide (1-4 and 16-64 micrograms/mouse i.c.v., respectively) reduced the antinociceptive effect of 8-OH-DPAT, whereas cromakalim (32-64 micrograms/mouse i.c.v.), an opener of KATP channels, enhanced the effect. In contrast, 4-aminopyridine (25-250 ng/mouse i.c.v.) and tetraethylammonium (10-20 micrograms/mouse i.c.v.), which antagonize several non-ATP-dependent K+ conductances, were inactive. The same results were found with other agonists of 5-HT1A receptors (lesopitron, buspirone and tandospirone): gliquidone inhibited whereas cromakalim increased their antinociceptive effects. None of the K+ channel-acting drugs modified the binding of [3H]8-OH-DPAT to hippocampal membranes, whereas all the 5-HT1A receptor agonists displaced the ligand. These results suggest that ATP-sensitive K+ conductances are involved in the antinociception induced by agonists of 5-HT1A receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1996

The NMDA receptor antagonist dizocilpine (MK-801) stereoselectively inhibits morphine-induced place preference conditioning in mice.

The effect of the non-competitive NMDA receptor antagonist dizocilpine (MK-801) on conditioned place preference induced by morphine was studied in mice. As expected, morphine (1-8 mg/kg, i.p.) elicited a significant preference for the drug-paired compartment. Pretreatment of mice with (+)-dizocilpine (0.1 and 0.2 mg/kg, i.p.), the more active dizocilpine enantiomer, dose-dependently reversed the conditioned place preference produced by morphine (4 mg/kg, i.p.), whereas (-)-dizocilpine (0.2 mg/kg, i.p.) did not modify morphine-induced effects. In contrast, both enantiomers of dizocilpine (at a dose of 0.2 mg/kg, i.p.) elicited a conditioned place preference. These data suggest that (1) NMDA receptors play a role in morphine-induced place preference, and (2) dizocilpine-reinforcing properties in the place preference paradigm do not seem to be dependent on NMDA receptor blockade.

Animals↗

PubMed1996

Comparative study of propofol versus midazolam in the sedation of critically ill patients: results of a prospective, randomized, multicenter trial.

OBJECTIVES: To compare the effectiveness, characteristics, duration of action, hemodynamic and biochemical effects, and side effects of propofol and midazolam used for continuous intravenous sedation of ventilated critically ill patients. DESIGN: Multicenter, prospective, randomized, nonblinded study. SETTING: Nine Spanish general intensive care units (ICUs). PATIENTS: Ninety-eight patients admitted to the ICU who were mechanically ventilated and required sedation for a minimum of 48 hrs. INTERVENTIONS: Propofol or midazolam was used for induction and maintenance of continuous intravenous sedation for a maximum of 5 days. The effectiveness of those two regimens was assessed according to their effects on ventilatory management and the presence of agitation. MEASUREMENTS AND MAIN RESULTS: In 93% of the patients studied, there was a medical cause necessitating mechanical ventilation. The mean (+/-SD) duration of sedation was 81 +/- 25 hrs and 88 +/- 27 hrs for the propofol and midazolam groups, respectively. The induction dose was 2.24 +/- 0.43 mg/kg over 318 +/- 363 secs for propofol, and 0.22 +/-0.07 mg/kg over 33 +/-29 secs for midazolam. The maintenance dose was 2.8 +/-1.1 mg/kg/hr for propofol and 0.14 +/- 0.10 mg/kg/hr for midazolam. There was no difference regarding the opiate and muscle relaxant requirements between the two groups. Sedation with propofol was more effective in achieving patient-ventilator synchrony than that with midazolam after the first hour of treatment (p < .01). Patients sedated with propofol awoke more rapidly and with less variability that those patients sedated with midazolam (23 +/- 16 mins vs. 137 +/- 185 mins, respectively, p < .05), particularly in those patients requiring deep sedation (27 +/- 16 mins vs. 237 +/- 222 mins, respectively, p < .01). No hemodynamic or biochemical changes were detected in any of the treatment groups. During induction, five patients in the propofol group and two patients in the midazolam group had hypotension. CONCLUSIONS: In this population of critically ill patients, propofol is an effective and safe alternative for sedation, with some advantages, such as short duration of action and high effectiveness over the conventional regimen with benzodiazepines and opiates.

Adolescent↗

PubMed1996

Great toe-to-hand transfer nourished by arterial inflow through the venous system.

Revascularization of tissues through their venous system is currently used in vascularized venous flaps and in replantation of some fingertips. A toe-to-hand transfer that suffered prolonged and unexplainable arterial spasm, unrelenting to the usual therapeutic measures, was revascularized through its venous system. Tissue perfusion in the toe began 24 hours after the vascular repairs were through, because arterial flow was hampered by the venous valves in the toe. Tissue perfusion was poor initially but became stable 72 hours postoperatively, and the toe survived. The only complications were epidermolysis and pseudoarthrosis. We consider this technique for tissue revascularization as a suitable salvage method in cases where all other therapeutic measures fail.

Adult↗

PubMed1996

Cromakalim differentially enhances antinociception induced by agonists of alpha(2)adrenoceptors, gamma-aminobutyric acid(B), mu and kappa opioid receptors.

The influence of the ATP-sensitive K+(KATP) channel opener cromakalim on the antinociception induced by agonists of several receptors coupled to pertussis toxin-sensitive G proteins, clonidine (alpha2 adrenoceptor), baclofen (gamma-aminobutyric acid(B) receptor), morphine (mu opioid receptor) and U50,488H (kappa opioid receptor), was evaluated with a tail-flick test in mice. The subcutaneous administration of clonidine (0.12-2 mg/kg), morphine (0.5-16 mg/kg), baclofen (2-16 mg/kg) and U50,488H (2-16 mg/kg) induced a dose-dependent antinociceptive effect. Cromakalim (8-64 microgram/mouse intracerebroventricularly [i.c.v.]) did not change tail-flick latency in control animals but produced a dose-dependent enhancement of the antinociception induced by clonidine and morphine, and shifted their dose-response curves to the left. These effects of cromakalim were antagonized dose dependently by the K(ATP) channel blocker gliquidone (0.1-8 microgram/mouse i.c.v.). On the other hand, cromakalim (16-64 microgram/mouse i.c.v.) did not significantly enhance the antinociception induced by baclofen and U50,488H and did not shift their dose-response curves. These results suggest that opening of the K(ATP) channels plays an important role in the antinociception mediated by alpha(2) adrenoceptors and mu opioid receptors, but not in that induced by gamma-aminobutyric acid(B) and kappa opioid receptors.

Animals↗

PubMed1996

[Chemical and biological evaluation of the effect of plant extracts against Plasmodium berghei].

Extracts from thirteen species of plants were evaluated by "in vivo" antimalarial test against plasmodium berghei effects. Significant activities were observed in the ethyl acetate and aqueous extracts, elaborated of Cedrela tonduzii leaves, Trichilia havanensis and Trichilia americana barks, Neurolaena lobata and Gliricidia sepium leaves and Duranta repens fruits. Compounds identified include flavanoids, coumarins, mellilotic acid and iridoids which some kind of biodynamic activity has previously been reported. The flavone quercetin 1 purified from C. tonduzii gave strong antimalarial activity, however, its respective glucosides (quercetin 3-glucoside 2 y robinine 7) showed little significant activity.

Animals↗

PubMed1995

Acquired immune dysfunction in rabbits experimentally infected with an infectious molecular clone of the bovine immunodeficiency virus (BIV127).

To investigate the effect of bovine immunodeficiency virus (BIV) infection on the rabbit immune system, we studied the proliferative responses of peripheral blood lymphocytes (PBLs) of rabbits experimentally inoculated with BIV. All BIV127-inoculated rabbits seroconverted after 6 weeks and remained seropositive over a prolonged period of time. Assays for specific lymphocyte reactivity to concanavalin A (Con A) were performed monthly for over 1 year. One-hundred percent of infected rabbits developed abnormally low T cell responses, as measured by Con A stimulation. By 3 months postinoculation, the PBL response to Con A was diminished and remained depressed for 6 months. All animals were clinically asymptomatic within 14 months of BIV inoculation. By 15 and 16 months postinoculation, two of three infected rabbits exhibited recurrent lowering of the T cell responsiveness including a decrease in absolute PBL counts. One of these animals died unexpectedly. Our results further confirmed that a functional impairment of lymphocytes was induced early in the course of BIV infection, prior to clinical disease. These findings suggested that BIV infection may mimic asymptomatic infection of human immunodeficiency virus (HIV) and provided further evidence of the importance of BIV-induced disease in rabbits as a relevant model for the study of AIDS.

Animals↗