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J Contreras

Publications and source records attributed to J Contreras.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Utility of 201Tl washout in syndrome X patients].

INTRODUCTION: The term Syndrome X defines a group of patients who present symptoms of typical angina pectoris, positive exercise test and normal coronaries in the arteriogram. This study aims to compare the results of 201Tl scan images and washout in Syndrome X patients. METHODS: 24 patients with typical angina and normal arteriogram and 30 normal controls were studied with 201Tl SPECT to evaluate uptake and washout. RESULTS: 201Tl perfusion defects were found in 3 out of 24 (12.5%) and washout defects in 22 out of 24 (91.6 %). There is a statistically significant reduction (0 < 0.05) in thallium uptake and washout in patients with syndrome X compared to the control group. In addition, patients with syndrome X had a higher thallium uptake at rest than during exercise compared to the healthy subjects. CONCLUSIONS: Analysis of the 201Tl washout and thallium uptake can provide addition information in the evaluation of patients with syndrome X since the visual assessment of the cardiac scintigraphy with 201Tl is of limited value. Alterations of the myocardial perfusion in patients with chest pain and normal coronaries can be detected non-invasively with a complete scintigraphic study.

Aged↗
PubMed1998

Nitrergic relaxation of the horse corpus cavernosum. Role of cGMP.

The involvement of nitric oxide (NO) and the mechanisms mediating neurogenic relaxation were investigated in the horse corpus cavernosum. NADPH-diaphorase activity was expressed in nerve fibres around arteries and muscular bundles in the horse trabecular tissue. Relaxations in response to electrical field stimulation were tetrodotoxin (10(-6) M)-sensitive, indicating their neurogenic origin. The NO synthase inhibitor, L-NO-arginine (L-NO-Arg, 3 x 10(-5) M), abolished the electrically induced relaxations, which were significantly reversed by L-arginine (3 x 10(-3) M). Exogenous NO (10(-6)-10(-3) M) evoked relaxations which were unaffected by L-NO-Arg. 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 5 x 10(-6) M), an inhibitor of guanylate cyclase activation by NO, reduced the relaxations in response to electrical stimulation and exogenous NO. Iberiotoxin (3 x 10(-8) M) or apamin (5 x 10(-7) M), inhibitors of large and small conductance Ca2+-activated K+ channels, respectively, and glibenclamide (3 x 10(-6) M), a blocker of ATP-sensitive K+ channels, failed to modify the relaxations with NO. It is suggested that NO is present in nerve fibres of the horse corpus cavernosum and relaxes smooth muscle through a guanylate cyclase-dependent mechanism. Neither Ca2+-activated nor ATP-sensitive K+ channels seem to be involved in these relaxations.

Adenosine Triphosphate↗
PubMed1998

DR non-B1 mismatches influence allogeneic MLR-induced TH1- or TH2-like cytokine responses in rhesus monkeys.

Human and nonhuman primates have multiple DR B1 and non-B1 alleles. However, the role of mismatched DR non-B1 alleles in primary alloimmune responses is not well understood. Macaques, which share close DNA homologies with human MHC genes and have a high number of beta-chain genes in the DR subregion, are preeminent preclinical models for immunologic studies of transplant tolerance and immunosuppression. In this study, we examined the effect of allogeneic MHC Class II DRB mismatches in Th1- and Th2-like cytokine responses elicited in one-way MLR cultures in rhesus macaques. An ELISPOT method was used to estimate cytokine secretion at the single cell level. Molecular typing for DRB1 and DR non-B1 alleles was performed by a moderate-high resolution PCR-SSP method using a panel of 55 primer pairs covering 74 DRB alleles and clusters. Of 35 unrelated combinations, 66% had multiple (> or = 2) allelic MM at DRB1 and DR non-B1 with no significant correlation between numbers of DRB1 and DR non-B1 mismatches. Pairs with 1 or 0 MM were assigned to a mono/null MM group to obtain sufficient numbers for statistical analysis. The pairs differing by multiple vs. mono/null DRB1 MM showed no significant difference in cytokine prevalence (P = 0.69). In contrast, high IFN-gamma/ IL4 SFC ratios were noted in pairs with multiple vs. mono/null DR non-B1 MM (p = 0.0009). IFN-gamma/IL-10 spot forming cell (SFC) ratios were consistent with IFN-gamma/IL-4 SFC ratios (r = 0.98). Multiple DR non-B1 mismatches showed a trend towards higher MLR proliferative responses, although the stimulation index did not reflect the dominant cytokine response. These observations suggest a bias towards Th1-like cytokine production under allostimulation with multiple DR non-B1 gene products. Further study of the primary structure of DR non-B1 determinants may be helpful in understanding the fine molecular mechanisms governing the regulation of cytokine profiles during allostimulation in primates.

Animals↗
PubMed1998

Synthesis and evaluation of tacrine-huperzine A hybrids as acetylcholinesterase inhibitors of potential interest for the treatment of Alzheimer's disease.

Seventeen polycyclic compounds related to tacrine and huperzine A have been prepared as racemic mixtures and tested as acetylcholinesterase (AChE) inhibitors. The conjunctive pharmacomodulation of huperzine A (carbobicyclic substructure) and tacrine (4-aminoquinoline substructure) led to compound 7jy, 2.5 times less active than tacrine as AChE inhibitor, but much more active than its (Z)-stereoisomer (7iy). Derivatives 7dy and 7ey, lacking the ethylidene substituent, showed to be more active than tacrine. Many other structural modifications of 7jy led to less active compounds. Compounds 7dy and 7ey also showed to be much more active than tacrine in reversing the partial neuromuscular blockade induced by d-tubocurarine.

Acetylcholinesterase↗
PubMed1998

Developmental follow-up of 6-7 year old children of mothers employed during their infancies.

This study followed up 92 children at ages 6-7 first studied as one-year-olds in order to determine differences in the developmental outcome of the offspring of employed as compared to "stay at home" mothers. The developmental domain evaluated in the 6-7 year old children was peer competence, rated by laboratory play and child psychological test instruments. Mothers' reports of children's behavioral pathology at age 6-7 correlated with a higher number of maternal work hours during the infant's first year, but the children did better during overall play situations. Age 1 attachment ratings better predicted free play social competence for the entire sample than did maternal hours of work absence, but girls accounted for statistical significance. Maternal sensitivity from infancy was associated with maternal reports of (low) problem behaviors; however, regression analyses did not support the hypothesis that relations between either work status or attachment and current problem behaviors were mediated by early maternal sensitivity.

Child Care↗
PubMed1998

Involvement of the L-arginine/nitric oxide neural pathway in non-adrenergic, non-cholinergic relaxation of the bovine oesophageal groove.

1. The distribution and localization of nitric oxide synthase (NOS) immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in the bovine oesophageal groove were investigated by immnunohistochemical and histochemical staining techniques. Functional in vitro studies were performed to correlate the presence of NOS-immunoreactivity (IR) and NADPH-d staining with smooth muscle relaxations involving the L-arginine/nitric oxide neural pathway in the bovine oesophageal groove activity. 2. NOS-IR and NADPH-d were expressed in nerve cell bodies of the myenteric, submucosal and intramuscular ganglia, and in nerve fibres distributed around blood vessels and throughout the different muscular layers of the bovine oesophageal groove. 3. In oesophageal groove strips treated with guanethidine (10(-5) M) and atropine (10(-7) M) to block noradrenergic neurotransmission and muscarinic receptors, respectively, electrical field stimulation (EFS, 0.5-32 Hz, 1 ms duration, 20-s trains) induced relaxations which were practically abolished by tetrodotoxin (TTX, 10(-6) M). 4. Incubation with an inhibitor of nitric oxide synthesis, NG-nitro-L-arginine (L-NOARG, 3 x 10(-5) M), significantly inhibited relaxations induced by EFS. This inhibition was partially reversed by L-arginine (L-arg, 5 x 10(-3) M). D-NOARG (3 x 10(-5) M) had no effect on EFS-induced relaxations. 5. NO added as an acidified solution of NaNO2 (10(-6) - 10(-3) M) and S-nitroso-L-cysteine (10(-7) - 10(-4) M) caused concentration-dependent relaxations of the bovine oesophageal groove. These relaxations were unaffected by L-NOARG (3 x 10(-5) M). 6. The presence of NO-synthesizing enzyme in nerves and ganglia, and the pharmacological evidence for NO-mediated smooth muscle relaxation suggested that the L-arg/NO neuronal pathway is involved in the inhibitory neurotransmission of the bovine oesophageal groove.

Animals↗
PubMed1998

Single dose study of the bioequivalence of two sustained-release theophylline formulations.

The relative bioavailability of theophylline (CAS 58-55-9) was evaluated after a single dose administration of two sustained-release theophylline tablet formulations: Controfilina-200 as test preparation (test) and a commonly used reference preparation (reference). The design of the study was crossover in twelve healthy volunteers, with a series of two experimental sessions. The two sessions were carried out at weekly intervals. Theophylline concentrations were measured by HPLC (high performance liquid chromatography). The bioavailability was compared using the parameters: AUC0-infinity (area under the concentration-time curve), Cmax (maximal theophylline concentration), tmax (time after drug intake at which the maximal concentration is reached) and Cmax/AUC0-infinity. The results of this study indicated that the new generic sustained-release tablet and the reference are bioequivalent when the same dosage is administered.

Adult↗
PubMed1998

[Toxic shock syndrome by group A beta-hemolytic streptococcus. Study of clonal relationship between a case and its contacts].

Group A Streptococcal infections have increased in severity and frequency worldwide. We report a female patient that was admitted by Group A Streptococcal lethal toxic shock syndrome due to pharyngitis as the primary focus and without cutaneous involvement. Streptococcus pyogenes was isolated from blood cultures and case definition fulfilled standard recommendations. Epidemiological studies among family members showed, that two children (aged 5 and 12 years) harbored the same strain in their pharynxes as confirmed by arbitrarily primed PCR (AP-PCR) using primers ERIC and Pn-1. Control strains were included in the analysis. None of three health care workers involved in intubation and laryngoscopic procedures with the patient carried S pyogenes. AP-PCR appears to be a useful and rapid procedure to demonstrate clonal relatedness among S pyogenes strains.

Adult↗
PubMed1997

Allergic reactions to anisakis simplex parasitizing seafood.

BACKGROUND: The ingestion of Anisakidae ssp larvae parasitized fish can cause anisakiasis. Allergic reactions after ingestion of safely cooked but parasitized fish have been reported. METHODS: Twenty-three patients who suffered allergic reactions after seafood ingestion, with negative skin tests were studied. Anisakis simplex sensitization was assessed by skin prick test and/or specific serum Immunoglobulin E (IgE). Total serum IgE and specific IgE against the implicated seafood and Ascaris lumbricoides were also determined. RESULTS: Manifestations of Anisakis simplex allergy were urticaria/angioedema (18/23) patients and anaphylaxis (5/23). Gastric symptoms were also observed (3/23). Sea fish and shellfish were implicated. Raw and cooked seafood ingestion caused reactions. Total serum IgE ranged from 13 to 7200 KU/L. Specific IgE to Anisakis simplex was positive (> 0.35 KU/L) in all patients, and skin tests were positive in 20. Serum-specific IgE and skin tests to the involved seafoods were negative in every patient. Serum-specific IgE to Ascaris lumbricoides was negative in 13 patients. No association between total IgE and the eosinophil count (r < 0.1) was observed, but there was some association between total IgE and specific IgE to Anisakis simplex (r = 0.58). CONCLUSION: Anisakis simplex sensitization is the cause of allergic reactions after seafood ingestion. It is important to pay attention to this new "food allergy" to diagnose correctly the etiology of adverse food reactions.

Adolescent↗
PubMed1997

[Massive tumorous pulmonary embolism in hepatocarcinoma].

Tumoral pulmonary embolism is among the causes of acute dyspnea in patients with neoplasia. This phenomenon, different to thrombotic embolism, occurs frequently in patients with lung, gastrointestinal, liver, breast and uterus neoplasia. It is usually asymptomatic and usually constitutes an autopsy finding in these patients. More rarely it manifests as a cor pulmonale which evolves subacutely. Exceptionally large tumoral emboli spread from a primary tumoral mass, and obstruct main pulmonary arterial vessels, causing a clinical picture indistinguishable from massive pulmonary thromboembolism. We present case of massive tumoral pulmonary embolism by an hepatocarcinoma. In spite of an early thrombolytic treatment the patient died from acute pulmonary hypertension.

Autopsy↗
PubMed1996

[Detection of residual ischemia after acute anterior myocardial infarction using Thallium-201 SPECT].

OBJECTIVES: To assess the utility of single photon emission computed tomography (SPECT) with Thallium-201 after anterior myocardial infarction at predischarge time in the detection of; a) the prevalence of isotopic redistribution in the infarct area or at a distance; b) the correlation between peri-infarction ischemia and the angiographic state of the infarct-related artery, and c) the correlation between ischemia at a distance and the presence of multivessel disease. MATERIAL AND METHOD: Seventy-three survivors of an uncomplicated anterior myocardial infarction, 67 men and 7 women, with a mean age of 56 +/- 9 years (34-70 range), underwent T1-SPECT after stress test (62 exercise test and 11 pharmacological Dipyridamole test) as well as coronarographic studies before discharge. Peri-infarction ischemia was defined as redistribution presence in the distribution territory of the left anterior descending artery (LAD) and was assessed in a semi-quantitative way scoring both stress and rest images that allowed the calculation of a redistribution index R (Stress Score-Rest Score/Stress Score). Ischemia at a distance was defined as redistribution presence in the territories of circumflex and right coronary arteries as assessed both by visual analysis (VA) and bull's eye polar maps (BE) or by washout imaging (WO). RESULTS: Peri-infarction ischemia (R > 0) was found in 48 (65.7%) patients; 43 with and 5 without significant residual lesions in the LAD and the absence of peri-infarction ischemia (R = 0) was found in 25 (34.3%) patients, 19 with and 6 without significant residual lesions in the LAD. Sensitivity and specificity for multivessel disease detection by ischemia at a distance was 64% and 85% respectively, for VA; 60% and 77% for BE; and 95% and 65% for WO. Combinations of different analytical methods (multiparametric approach) showed a decrease in sensitivity but improved specificity and positive predictive value: 60%, 90% and 75%, respectively, for BE & WO; 44%, 90% and 69% for VA & BE and 60%, 92% and 79% for VA & WO. CONCLUSIONS: TI-SPECT imaging is a useful diagnostic method to detect both peri-infarction ischemia and ischemia at a distance at predischarge time following anterior myocardial infarction. Redistribution presence in the non infarct-area shows a fair sensitivity and a high positive predictive value to detect residual multivessel disease.

Adult↗
PubMed1996

[Follow-up of left ventricular systolic function in the first year following previous infarction].

OBJECTIVES: To follow the left ventricular systolic function changes as assessed by global and regional ejection fraction during the first year of evolution after anterior myocardial infarction, as well as to analyse how the most relevant clinical and angio-graphic parameters influence them. MATERIALS AND METHODS: Sixty-six consecutive patients with a first infarction of anterior location, completed 1 year of follow-up with radionuclide ventriculography, T1-SPECT after exercise or dypiridamole and cardiac catheterization before discharge; radionuclide ventriculography was repeated 6 and 12 months later. Twenty-five patients underwent revascularization procedures at the time of predischarge, 16 using successful percutaneous angioplasty of the left anterior descending artery and 9 using aorto-coronary graft surgery. Dilated patients were controlled, from an angiographic point, of view 6 months after PTCA. RESULTS: Predischarge global EF (42.9 +/- 12.6) increased significantly between the 6-month (46.9 +/- 12.8; p < 0.001) and 12-month (47.6 +/- 12; p < 0.001) studies. Differences in these two last studies were minor and had no statistical significance. A significant increase was present in revascularized or medically treated patients; i.e. those who underwent thrombolytic therapy or conventional treatment at admittance as well as mono or multivessel disease patients. No significant differences were detected in the mean ejection fraction in patients without residual stenosis in the infarct-related artery (48.1 +/- 13.3 vs 50 +/- 12.6; NS) or those presenting a pre-discharge ejection fraction > or = 45% (53.5 +/- 7.5 vs 55.1 +/- 3.3; NS). Among different variables tested, predischarge global ejection fraction (negative coefficient) and, to a lesser extent, percutaneous angioplasty were independent predictors of a significant increase of ejection fraction during follow-up. Changes from predischarge to 12 month study were significant in the regional ejection fraction in the anteroseptal (33.1 +/- 14.7 vs 40.1 +/- 13.3; p < 0.001), inferoseptal (34.6 +/- 15.8 vs 42 +/- 16.9; p < 0.001), apical (46.3 +/- 19.1 vs 50.8 +/- 19.7; p < 0.01), antero-medial (50.6 +/- 22.4 vs 56.6 +/- 24.3; p < 0.01) and anteroapical (51.6 +/- 23.5 vs 58 +/- 27.5; p < 0.01) segments. In the anterobasal segment, regional ejection fraction only showed a statistical tendency to increase during follow-up and changes in inferior and lateral segments, distal to the infarcted area, were minor and without statistical significance. The most distinct infarct-related segments, antero- and inferoseptal, showed significant increases in the main group of patients, revascularized or nonrevascularized, undergoing thrombolitic or conventional therapy, with single or multivessel disease. Only patients without residual stenosis of the infarct-related artery (the left descending anterior) disclosed negligible or negative changes without statistical significance. Percutaneously dilated patients showed the highest increase of the infarct-related segments regional ejection fraction. In multivessel disease, the infarct-related segments regional ejection fraction did not increase significantly in surgically treated patients, conversely to those who underwent medical therapy. CONCLUSIONS: Global and regional ejection fraction of the infarcted area increased significantly during the first year after anterior myocardial infarction, mainly prior to six months patients with significant residual stenosis of the artery related to the infarct. Recovery is present both in patients who underwent thrombolysis or conventional treatment at admittance and revascularization or medical treatment before discharge and is inversely correlated to the predischarge global ejection fraction value. This evolution suggests that a significant amount of stunned myocardium is still present before discharge.

Adult↗
PubMed1995

Plasmodium falciparum: characterization of a 0.7-kbp, moderately repetitive sequence.

A 692-bp-long repetitive sequence of Plasmodium falciparum was cloned. Two contiguous repeats were sequenced. The homology between them was 85%, the differences being due only to base replacements. The sequence was found 60 times repeated in the genome and was detected in 11 of 14 chromosomes. When used as a probe, the cloned fragment detected the parasite with the same sensitivity the 21-bp repeat (pRepHind) did. PCR amplification detected 0.02 pg of DNA, equivalent to a single parasite, in strains from America, Asia, and Africa. The restriction patterns were polymorphic and different among the strains. Analysis of lambda EMBL clones that contain the repetitive sequence confirms that it is present in various genomic contexts and is located subtelomerically.

Animals↗
PubMed1995

5-hydroxytryptamine inhibits pressor responses to preganglionic sympathetic nerve stimulation in pithed rats.

5-Hydroxytryptamine (5-HT) inhibits contractile responses to adrenergic nerve stimulation in several blood vessels and organs. We have now investigated the potential ability of 5-HT to inhibit the pressor responses caused by preganglionic sympathetic stimulation (T7-T9) in pithed rats. Sympathetic stimulation (0.03, 0.1, 0.3, 1 and 3 Hz) resulted in frequency-dependent increases in diastolic blood pressure; these effects were augmented after i.v. treatment with desipramine (50 micrograms/kg). During continuous infusions of 5-HT (1.8, 3.1, 5.6 and 10 micrograms/kg.min, i.v.), but not of saline, the pressor responses were dose-dependently inhibited in both control and desipramine-pretreated rats; this inhibitory effect of 5-HT was significantly more pronounced at lower frequencies of stimulation. In contrast, the above infusions of 5-HT did not inhibit the pressor responses induced by i.v. bolus injections of exogenous norepinephrine (up to 3 micrograms/kg). Taken together, the above findings suggest an operative 5-HT-induced prejunctional inhibition of sympathetic nerve activity on the systemic vasculature in vivo.

Animals↗
PubMed1995

Characterization of prejunctional 5-HT receptors mediating inhibition of sympathetic vasopressor responses in the pithed rat.

1. It has recently been shown that continuous infusions of 5-hydroxytryptamine (5-HT) are able to inhibit, in a dose-dependent manner, the pressor responses induced by preganglionic (T7-T9) sympathetic stimulation in pithed rats pretreated with desipramine (50 micrograms kg-1, i.v.). This inhibitory effect, besides being significantly more pronounced at lower frequencies of stimulation (0.03-I Hz) and devoid of tachyphylaxis, is reversible after interrupting the infusions of 5-HT (up to 5.6 micrograms kg-1 min-1). In the present study we have characterized the pharmacological profile of the receptors mediating the above inhibitory effect of 5-HT. 2. The inhibition induced by 5.6 micrograms kg-1 min-1 of 5-HT on sympathetically-induced pressor responses was not blocked after i.v. treatment with physiological saline (1 ml kg-1), ritanserin (0.1 mg kg-1), MDL 72222 (0.15 mg kg-1) or tropisetron (3 mg kg-1), which did not modify the sympathetically-induced pressor responses per se, but was significantly antagonized by the 5-HT1-like and 5-HT2 receptor antagonist, methysergide (0.3 mg kg-1), which also produced a slight attenuation of the pressor responses to 0.03 and 0.1 Hz per se. 3. Unexpectedly and contrasting with methysergide, the 5-HT1-like and 5-HT2 receptor antagonists, methiothepin (0.01, 0.03 and 0.1 mg kg-1) and metergoline (1 and 3 mg kg-1), apparently failed to block the above 5-HT-induced inhibition. Nevertheless, it is noteworthy that these antagonists also blocked the electrically-induced pressor responses per se, presumably by blockade of vascular alpha 1-adrenoceptors and, indeed, this property might have masked their potential antagonism at the inhibitory 5-HT1-like receptors. 4. Consistent with the above findings, 5-carboxamidotryptamine (5-CT, a potent 5-HT1-like receptor agonist), metergoline and methysergide mimicked the inhibitory action of 5-HT with the following rank order of agonist potency: 5CT > > 5-HT > metergoline > or = methysergide. 5. Taken together, the above results suggest that the inhibitory action of 5-HT on the electrically-induced pressor responses is primarily mediated by an action on inhibitory prejunctional 5-HT1-like receptors leading to a decrease in the sympathetic nerve discharge. Interestingly, 5-HT-induced excitatory mechanisms could be made manifest once the inhibitory action of 5-HT had been antagonized.

Animals↗