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Biomedical subjects

J Duarte

Publications and source records attributed to J Duarte.

At least 55 records · Page 3Linked to original sources
PubMed1996

Incidence of transient ischemic attacks and minor ischemic strokes in Segovia, Spain.

BACKGROUND AND PURPOSE: The aim of this study was to determine the incidence of transient ischemic attacks (TIAs) and minor ischemic strokes (MISs) in Segovia, Spain. METHODS: A 2-year prospective community-based register of TIAs and MISs established in Segovia from February 16, 1992, to February 15, 1994. Every patient underwent underwent a complete clinical evaluation and cranial CT scan. Sex- and age-specific incidence rates with 95% confidence intervals (CIs) were calculated for all ages. RESULTS: The total series included 235 patients; 103 suffered TIAs and 132 suffered MISs. Mean age was 70.8 years (range, 29 to 96 years); 92 were women and 143 were men. The crude annual incidence was 0.80/1000 (95% CI, 0.70 to 0.90): 0.35/1000 (95% CI, 0.28 to 0.42) for TIAs and 0.45/1000 (95% CI, 0.37 to 0.53) for MISs. The incidence of TIAs and MISs increased with age. Approximately 78 of TIAs and MISs were in the carotid distribution, 19% were vertebrobasilar, and 3% were considered of uncertain vascular distribution. Cranial CT scan was performed in all patients. CT showed cerebral infarcts in 30.1% (31/103; 95% CI, 21% to 39%) of TIAs and 70% (92/132; 95% CI, 62% to 78%) of MISs (P<.00001). CONCLUSIONS: Our study is the first community-based register that provides sex-and age-specific rates for MISs and in which a CT scan was obtained in all patients. The incidence of TIAs in Segovia is comparable to that in other previous similar studies.

Adolescent↗
PubMed1996

[Cerebral infarct as a presentation of a hereditary defect of type II C protein].

The case of a 50 year-old patient with a cerebral infarct related to a deficit in type II C protein is described. The patient showed no other vascular risk factor and the cardiological study, which included a transthoracic and a transoesophagic echogram ruled out the presence of embologenic cardiopathy. A family study detected the presence of a deficit of C protein in 6 of the 8 sons and in the patient's sister who had a deep vein thrombosis at the age of 54. A hereditary deficiency in C protein was confirmed. We consider it necessary to perform hypercoagulability studies which include the determination of C protein in patients under 55 years of age with cerebral infarcts of unknown cause, especially when there is a family history of thrombosis.

Brain↗
PubMed1995

Vasodilator effects of visnagin in isolated rat vascular smooth muscle.

Visnagin (4-methoxy-7-methyl-5H-furo [3,2-g][1]-benzopyran-5-one) is an active principle of the fruit of Ammi visnaga, a plant traditionally used in cardiovascular disorders. We have studied its vasodilator effects in rat vascular smooth muscle. The results demonstrated that visnagin inhibited the contractile responses induced in rat aortic rings by: (a) KCl or increases of extracellullar Ca2+ in KCl depolarized aortic rings, its effects being more potent against low (20 mM) than high (80 mM) KCl-induced contractions, (b) noradrenaline in Ca(2+)-containing solution and less effectively those in Ca(2+)-free solution and (c) phorbol 12-myristate 13-acetate (PMA) in a Ca(2+)-containing and with a lower potency in Ca(2+)-free medium. The relaxation induced by visnagin in aorta precontracted with noradrenaline was not affected by endothelium removal. Additionally, visnagin inhibited the spontaneous myogenic contractions of portal veins. The results showed that visnagin inhibited vascular smooth muscle contractility by acting at multiple sites. In the range of 10(-6) M to 5 x 10(-5) M visnagin appears to inhibit only the contractions mediated by Ca2+ entry through pathways with low sensitivity to classical Ca(2+)-entry blockers, i.e. agonist-, PMA- or mild depolarization-induced Ca2+ entry. Therefore, the vasodilator profile of visnagin, is not that of typical Ca(2+)-entry blockers which preferentially inhibit the contractions induced by strong depolarizations. At higher concentrations (> 5 x 10(-5) M) visnagin causes non-specific inhibition of vascular smooth muscle contractility.

Animals↗
PubMed1995

Screening Parkinson's disease: a validated questionnaire of high specificity and sensitivity.

A questionnaire designed to screen Parkinson's disease (PD) in literate populations has been developed. It consists of nine questions, self-administered at medical facilities or by mail, and a scale of weights for ascribing scores to specific questions when the answer is positive. The questions were chosen to be symptom specific for PD and the weights were determined from answers provided by 37 PD patients in a neurological outpatient clinic. The questionnaire sensitivity was tested on a different PD population from the same outpatient clinic--50 individuals--and the specificity on a group of 100 ophthalmological patients. The sensitivity was 100% and the specificity was 100%. Three individuals who screened positive among the 100 ophthalmological patients were assessed and given a new diagnosis of PD. This questionnaire therefore constitutes an instrument that should prove valuable as the first stage of a door-to-door survey. It has high sensitivity and specificity.

Adult↗
PubMed1995

Association between the oxidative polymorphism and early onset of Parkinson's disease.

The frequency of five cytochrome P450IID6 allelic variants was studied in deoxyribonucleic acid from 123 patients with Parkinson's disease and 150 healthy volunteers. This was achieved by the use of mutation-specific polymerase chain reaction and restriction fragment length polymorphism. The analyses of the CYP2D6 genotype revealed no evidence for a higher prevalence of poor metabolizers among patients with Parkinson's disease. However, increased frequency of patients with Parkinson's disease with the genotype CYP2D6wt/CYP2D6B was observed. This is attributable exclusively to subjects with early onset of the disease (28 to 49 years), with a relative risk ratio of 4.16 (95% confidence limits, 2.0 to 8.3; p < 0.0005). The subjects who had late-onset Parkinson's disease (> or = 50 years) had genotypes and CYP2D6 allele frequencies similar to the healthy subjects. This indicates that the oxidative polymorphism is related to early-onset but not to late-onset Parkinson's disease. A different influence of CYP2D6 genotype on the risk of development of Parkinson's disease is observed in Spaniards, compared with previous findings in British subjects. These results suggest the combined effect of environmental toxins and CYP2D6 in the cause of Parkinson's disease.

Adult↗
PubMed1995

Aggravation of parkinsonian tremor by cisapride.

Cisapride, a substituted piperidinyl benzamide that is chemically related to metoclopramide, is a prokinetic agent that facilitates motility of the gastrointestinal tract (1). The mechanism by which cisapride exerts its actions is not clear. It enhances acetylcholine release in the myenteric plexus of the gut, and evidence exists that it has an agonistic action on a serotonin receptor, probably the 5-HT4 receptor (2). The drug is well tolerated, and no central nervous system side effects have been reported. We describe two patients with parkinsonism who experienced aggravation of tremor while on therapy with cisapride.

Aged↗
PubMed1995

Changes in cerebral blood flow as monitored by transcranial Doppler during voluntary hyperventilation and their effect on the electroencephalogram.

Hyperventilation results in a fall in carbon dioxide concentration, a fall in cerebral blood flow, and slowing of activity on the electroencephalogram. The temporal relationship and duration of these responses are uncertain, and were investigated using simultaneous monitoring of cerebral blood flow velocity and of the electroencephalograph, with end-tidal carbon dioxide monitoring. Sixteen patients and 9 normal volunteers were studied. Cerebral blood flow velocity in the middle cerebral artery was measured using transcranial Doppler sonography during 3 minutes of hyperventilation and during a 3-minute recovery period. Electroencephalographic recordings were rated by both visual score and measurement of the dominant posterior frequency. End-tidal expired carbon dioxide tension was monitored during the same hyperventilation protocol in the volunteers. Flow velocity fell rapidly during active hyperventilation. Electroencephalographic slowing closely correlated with the decrease in flow velocity (r = 0.86), but lagged behind it. In healthy volunteers capnographic records showed a very tight coupling between end-tidal carbon dioxide concentration and flow velocity (r = 0.94). Three minutes after hyperventilation, carbon dioxide concentration, cerebral blood flow velocity, and electroencephalographic activity were still not back to the resting state. The fall in both cerebral blood flow velocity and carbon dioxide concentration are related to but precede electroencephalographic slowing. The abnormalities persist for at least 3 minutes after hyperventilation and this must be taken into account in clinical electroencephalography. Transcranial Doppler sonography is well suited to monitoring short-term changes in the cerebral circulation.

Adult↗
PubMed1994

Inhibitory effects of quercetin and staurosporine on phasic contractions in rat vascular smooth muscle.

The aim of this work was to analyze the effects of quercetin and staurosporine on the phasic contractile responses in rat aorta induced by noradrenaline, 5-hydroxytryptamine (5-HT, serotonin) and caffeine in Ca(2+)-free media. Both quercetin and staurosporine inhibited the contractions induced by 10(-5) M noradrenaline, 10(-5) M 5-HT and 20 mM caffeine in Ca(2+)-free solution. Phorbol 12-myristate 13-acetate (5 x 10(-8) M) enhanced this transient contraction elicited by noradrenaline, an effect that was abolished by quercetin (5 x 10(-5) M). The relaxant effects of quercetin on 80 mM KCl induced contractions were similar in normal and low Na+ solution, e.g. when Ca2+ efflux through the Na+/Ca2+ exchanger was inhibited. Furthermore, quercetin or staurosporine had no effect on 45Ca2+ efflux under resting conditions or when stimulated by 10(-5) M noradrenaline. These results suggested that the inhibitory effects of quercetin and staurosporine on phasic contractile responses induced by receptor agonists in Ca(2+)-free media do not seem to be related to changes in cellular Ca2+ regulation but to an inhibitory effect on the regulation of contractile proteins, an effect probably related to the decreased sensitivity of contractile elements to Ca2+ that apparently resulted from the inhibitory effects of quercetin and staurosporine on protein kinases.

Alkaloids↗
PubMed1994

Herpes simplex brainstem encephalitis with a relapsing course.

We report a patient with a relapsing form of acute brainstem encephalitis. Pathological examination demonstrated necrotizing encephalitis in the cerebral cortex and, more pronounced, throughout the diencephalon, as well as in the pes pontis. Neurons and glial cells in the cerebral cortex and brainstem contained herpesvirus antigens. The clinical interrelationship of brainstem encephalitis, Miller Fisher syndrome and Landry-Guillain-Barré syndrome is discussed.

Adolescent↗
PubMed1994

Development and clinical assay of the BCM ventricular assist device.

The development of a ventricular assist device is depicted. The seven subprograms that make up the project are described briefly. Results obtained during the clinical assay showed that the new design of the input cannula working as a false auricle provides better efficiency, as well as a certain level of autoregulation for the device.

Aged↗