Search PubMed⌕ Search

Biomedical subjects

J A Silva

Publications and source records attributed to J A Silva.

At least 37 records · Page 2Linked to original sources
PubMed2001

Percutaneous profundaplasty in the treatment of lower extremity ischemia: results of long-term surveillance.

PURPOSE: To assess the procedural and long-term clinical outcomes of balloon angioplasty of the profunda femoris artery in patients with severe limb ischemia. METHODS: Thirty-one consecutive patients were evaluated for severe ischemia in 32 limbs: 13 (41%) were categorized Fontaine class 2B, and 19 (59%) were class 3 or 4. The superficial femoral artery was occluded in 20 (62%) limbs; an additional vessel was treated in 22 (69%) limbs. RESULTS: Procedural success was achieved in 91% (31/32) of limbs. The ankle-brachial index increased from 0.5 +/- 0.2 at baseline to 0.7 +/- 0.2 after intervention (p < 0.01). In-hospital limb salvage was 94% (30/32), and in-hospital event-free survival was 90% (28/31). At a mean follow-up of 34 +/- 20 months, no additional amputations were necessary; 3 patients required repeat revascularization, and 5 patients died. Freedom from revascularization was 88% in the 25 survivors. At follow-up, 88% of the patients had Fontaine class 1 or 2A symptoms, and only 12% had Fontaine class 2B or higher (p < 0.001 compared with baseline). CONCLUSIONS: These data suggest that percutaneous profundaplasty is safe, effective, and may be considered as an alternative to surgical therapy in patients with anatomically suitable lesions.

Aged↗
PubMed2001

A classification of psychological factors leading to violent behavior in posttraumatic stress disorder.

Posttraumatic stress disorder has long been linked to violent behavior. However, the exact nature of that association remains poorly characterized due to the limitations of knowledge in the area of phenomenology, contextual factors, the biology, and the nature of the aggression involved in the disorder. A clear understanding of the genesis of violence in posttraumatic stress disorder can be helpful to those involved in assessing psychiatric-legal issues relevant to the disorder and in its therapeutic management. In this article, we review the potential psychological links between posttraumatic stress disorder secondary to combat exposure and violent behavior and suggest a tentative classification of the main psychological causes of violence in that syndrome.

Adult↗
PubMed2001

Delusional misidentification and aggression in Alzheimer's disease.

Alzheimer's disease has been associated with serious behavioral disturbances including aggressive behaviors and agitation. Aggression in dementia of the Alzheimer's type may be associated with psychotic symptoms, particularly delusional misidentification phenomena. These phenomena are complex and varied in Alzheimer's disease and so far have been only rudimentarily described. In this paper, we explore the association of delusional misidentification and aggression in an individual suffering from Alzheimer's disease.

Aged↗
PubMed2001

T wave positivity in resting electrocardiogram predicts preserved systolic thickening in chronic anterior Q wave myocardial infarction: an echocardiographic study.

AIM: After ST elevation myocardial infarction, ST segment and T wave changes generally resolve, but in some patients T waves keep their negative components for a long time. The aim of this study is to evaluate the pathophysiological implications of persistent negative T waves and restored positive T waves in the chronic stage of Q wave myocardial infarction. METHODS: We studied 30 patients with a previous anterior wall ST elevation myocardial infarction (more than one year follow-up) and presenting Q waves in at least three consecutive precordial leads in the standard 12-lead electrocardiogram at rest. Patients were divided into two groups according to the T wave pattern in leads with Q waves: positive T group consisting of patients in whom all T wave components showed an upright configuration; and a negative T group consisting of patients in whom T waves were are least partly inverted. We used echocardiography to measure systolic thickening of the interventricular septum within the infarction area. Systolic thickening was considered significant when end-systolic thickness was greater than end-diastolic thickness by > 25% in proportion and > 1 mm in absolute value. RESULTS: Significant systolic thickening was demonstrated in 14 (74%) of the 19 positive T patients and in one (9%) of the 11 negative T patients (odds ratio 8.1; 95% CI, 1.2 to 53.5; p = 0.002). CONCLUSION: In the chronic stage of a myocardial infarction, restored T wave positivity predicts preserved systolic thickening, suggesting the presence of viable and normally contracting myocytes within the infarction area. Further studies are needed to establish the prognostic value of T wave characteristics in patients with a past history of myocardial infarction.

Chronic Disease↗
PubMed2001

[Constrictive pericarditis: an early diagnosis?].

The authors report a case study of a 73-year-old male, with signs of right-sided heart failure with 6 months of evolution. It was constrictive pericarditis, without radiologic, echocardiographic and magnetic resonance imaging manifestations, diagnosed on the basis of the clinical situation and hemodynamic evaluation during cardiac catheterization. The authors suggest that the lack of imagiologic manifestations might have been the result of an early diagnosis, before the development of the classic picture. Pericardiectomy, performed with success, was followed by resolution of the heart failure. It was not possible, histologically, to draw conclusions about the etiology. The development of mitral regurgitation after pericardiectomy has enriched this case with an unusual, but previously described, complication of this type of surgery.

Aged↗
PubMed2000

Regional metabolic effects of fluoxetine in major depression: serial changes and relationship to clinical response.

BACKGROUND: Treatment of major depression with antidepressants is generally associated with a delay in onset of clinical response. Functional brain correlates of this phenomenon have not been previously characterized. METHODS: Time course of changes in brain glucose metabolism were measured using positron emission tomography in hospitalized unipolar depressed patients treated with fluoxetine. Time-specific and response-specific effects were examined at 1 and 6 weeks of treatment. RESULTS: Changes were seen over time, and characterized by three distinct patterns: 1) common changes at 1 and 6 weeks, 2) reversal of the 1-week pattern at 6 weeks, and 3) unique changes seen only after chronic treatment. Fluoxetine responders and nonresponders, similar at 1 week, were differentiated by their 6-week pattern. Clinical improvement was uniquely associated with limbic and striatal decreases (subgenual cingulate, hippocampus, insula, and pallidum) and brain stem and dorsal cortical increases (prefrontal, parietal, anterior, and posterior cingulate). Failed response was associated with a persistent 1-week pattern and absence of either subgenual cingulate or prefrontal changes. CONCLUSIONS: Chronic treatment and clinical response to fluoxetine was associated with a reciprocal pattern of subcortical and limbic decreases and cortical increases. Reversal in the week-1 pattern at 6 weeks suggests a process of adaptation in specific brain regions over time in response to sustained serotonin reuptake inhibition. The inverse patterns in responders and nonresponders also suggests that failure to induce these adaptive changes may underlie treatment nonresponse.

Brain↗
PubMed2000

Hypoalgesia and altered inflammatory responses in mice lacking kinin B1 receptors.

Kinins are important mediators in cardiovascular homeostasis, inflammation, and nociception. Two kinin receptors have been described, B1 and B2. The B2 receptor is constitutively expressed, and its targeted disruption leads to salt-sensitive hypertension and altered nociception. The B1 receptor is a heptahelical receptor distinct from the B2 receptor in that it is highly inducible by inflammatory mediators such as bacterial lipopolysaccharide and interleukins. To clarify its physiological function, we have generated mice with a targeted deletion of the gene for the B1 receptor. B1 receptor-deficient animals are healthy, fertile, and normotensive. In these mice, bacterial lipopolysaccharide-induced hypotension is blunted, and there is a reduced accumulation of polymorphonuclear leukocytes in inflamed tissue. Moreover, under normal noninflamed conditions, they are analgesic in behavioral tests of chemical and thermal nociception. Using whole-cell patch-clamp recordings, we show that the B1 receptor was not necessary for regulating the noxious heat sensitivity of isolated nociceptors. However, by using an in vitro preparation, we could show that functional B1 receptors are present in the spinal cord, and their activation can facilitate a nociceptive reflex. Furthermore, in B1 receptor-deficient mice, we observed a reduction in the activity-dependent facilitation (wind-up) of a nociceptive spinal reflex. Thus, the kinin B1 receptor plays an essential physiological role in the initiation of inflammatory responses and the modulation of spinal cord plasticity that underlies the central component of pain. The B1 receptor therefore represents a useful pharmacological target especially for the treatment of inflammatory disorders and pain.

Animals↗
PubMed2000

Synchronism in a metapopulation model.

We consider a spatially explicit meta-population model with interaction among the two nearest neighbors to relate, with a simple mathematical expression, chaos in the local, uncoupled, populations, the degree of interaction among patches, size of the meta-population, and the stability of the synchronized attractor. Since synchronism is strongly correlated with extinction, our results can provide useful information on factors leading to population extinction.

Animals↗
PubMed2000

Purification and characterisation of vanadium haloperoxidases from the brown alga Pelvetia canaliculata.

Two enzymes characterised as iodoperoxidases (PcI and PcII), with vanadium-dependent activity, have been purified from the brown alga Pelvetia canaliculata (L.) Decne et Thur. (Fucaceae, Phaeophyceae), collected in the Northern Portuguese coast, at Viana do Castelo. The relative molecular masses were 166 kDa for PcI and 416 kDa for PcII, as determined by gel filtration. SDS-PAGE shows that PcI has just one band corresponding to a subunit of 66 kDa, while PcII shows four bands (66, 72, 157 and 280 kDa). The following kinetic parameters have been determined from a steady-state analysis of the oxidation of iodide by H2O2: PcI, pHopt = 6.0, KM(I-) = 2.1 mM, KM(H2O2) = 110 microM, Ki(I-) = 127 mM; and PcII, pHopt = 6.5, KM(I-) = 2.4 mM, KM(H2O2) = 20 microM and Ki(I-) = 69 mM. These iodoperoxidases are thermostable, as also observed for vanadium bromo- and chloroperoxidases.

Catalytic Domain↗
PubMed2000

Reduced cardiac hypertrophy and altered blood pressure control in transgenic rats with the human tissue kallikrein gene.

To evaluate the cardiovascular actions of kinins, we established a transgenic rat line harboring the human tissue kallikrein gene, TGR(hKLK1). Under the control of the zinc-inducible metallothionein promoter, the transgene was expressed in most tissues including the heart, kidney, lung, and brain, and human kallikrein was detected in the urine of transgenic animals. Transgenic rats had a lower 24-h mean arterial pressure in comparison with control rats, which was further decreased when their diet was supplemented with zinc. The day/night rhythm of blood pressure was significantly diminished in TGR(hKLK1) animals, whereas the circadian rhythms of heart rate and locomotor activity were unaffected. Induction of cardiac hypertrophy by isoproterenol treatment revealed a marked protective effect of the kallikrein transgene because the cardiac weight of TGR(hKLK1) increased significantly less, and the expression of atrial natriuretic peptide and collagen III as markers for hypertrophy and fibrosis, respectively, were less enhanced. The specific kinin-B2 receptor antagonist, icatibant, abolished this cardioprotective effect. In conclusion, the kallikrein-kinin system is an important determinant in the regulation of blood pressure and its circadian rhythmicity. It also exerts antihypertrophic and antifibrotic actions in the heart.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

The brain renin-angiotensin system modulates angiotensin II-induced hypertension and cardiac hypertrophy.

The potential involvement of the brain renin-angiotensin system in the hypertension induced by subpressor doses of angiotensin II was tested by the use of newly developed transgenic rats with permanent inhibition of brain angiotensinogen synthesis [TGR(ASrAOGEN)]. Basal systolic blood pressure monitored by telemetry was significantly lower in TGR(ASrAOGEN) than in Sprague-Dawley rats (parent strain) (122.5+/-1.5 versus 128.9+/-1.9 mm Hg, respectively; P<0.05). The increase in systolic blood pressure induced by 7 days of chronic angiotensin II infusion was significantly attenuated in TGR(ASrAOGEN) in comparison with control rats (29.8+/-4.2 versus 46. 3+/-2.5 mm Hg, respectively; P<0.005). Moreover, an increase in heart/body weight ratio was evident only in Sprague-Dawley (11.1%) but not in TGR(ASrAOGEN) rats (2.8%). In contrast, mRNA levels of atrial natriuretic peptide (ANP) and collagen III in the left ventricle measured by ribonuclease protection assay were similarly increased in both TGR(ASrAOGEN) (ANP, x2.5; collagen III, x1.8) and Sprague-Dawley rats (ANP, x2.4; collagen III, x2) as a consequence of angiotensin II infusion. Thus, the expression of these genes in the left ventricle seems to be directly stimulated by angiotensin II. However, the hypertensive and hypertrophic effects of subpressor angiotensin II are at least in part mediated by the brain renin-angiotensin system.

Angiotensin II↗
PubMed2000

Evaluation of competence to consent to assisted suicide: views of forensic psychiatrists.

OBJECTIVE: Mental health evaluation of competence to consent has been proposed as an important safeguard for patients requesting assisted suicide, yet mental health professionals have not developed guidelines or standards to aid in such evaluations. The authors surveyed a national sample of forensic psychiatrists in the United States regarding the process, thresholds, and standards that should be used to determine competence to consent to assisted suicide. METHOD: An anonymous questionnaire was sent to board-certified forensic psychiatrists between August and October 1997. RESULTS: Of the 456 forensic psychiatrists who were sent the questionnaire, 290 (64%) responded. Sixty-six percent believed that assisted suicide was ethical in at least some circumstances, and 63% thought that it should be legalized for some competent persons. Twenty-four percent indicated that it was unethical for psychiatrists to determine competence; however, 61% thought such an evaluation should be required in some or all cases. Seventy-eight percent recommended a very stringent standard of competence. Seventy-three percent believed that at least two independent examiners were needed to determine competence, and 44% favored requiring judicial review of a decision. Fifty-eight percent believed that the presence of major depressive disorder should result in an automatic finding of incompetence. Psychiatrists with ethical objections to assisted suicide advocated a higher threshold for competence and more extensive review of a decision. CONCLUSIONS: The ethical views of psychiatrists may influence their clinical opinions regarding patient competence to consent to assisted suicide. The extensive evaluation recommended by forensic psychiatrists would likely both minimize this bias and assure that only competent patients have access to assisted suicide, but the process might burden terminally ill patients.

Attitude of Health Personnel↗
PubMed2000

Seasonal variation of nutrients and energy in tambaqui's (Colossoma Macropomum Cuvier, 1818) natural food.

The aim of this study was to evaluate the importance of fruits and seeds as food items in the natural diet of the tambaqui (Colossoma macropomum). During one year, tambaqui's stomach contents were collected, and their nutritional and energetic values were determined. During the flooding period, and while the river water was rising, which coincided with a high availability of fruits and seeds, the protein content of food was low (11%-15% of dry matter basis), whereas in the dry season, when tambaqui fed mainly zooplankton, there was a high protein content (45%-57% of dry matter basis). Lipid, carbohydrate, crude fiber, ash and gross energy contents of the diet varied depending on the river water level and the food items ingested.

Animals↗
PubMed2000

Stalking behavior in delusional jealousy.

Stalking behavior has been associated with several mental disorders, both psychotic and non-psychotic. The most frequently associated condition appears to be an individual with primitive personality psychopathology regardless of co-occurring psychotic symptomatology. Among the psychotic symptoms, erotomanic, and jealousy delusions may be the most clinically and torensically relevant. However, delusional jealousy has not been well appreciated in the psychiatric literature as an important contributor to stalking behavior. In this article, we explore the psychiatric, psychosocial, and forensic aspects of stalking in the context of delusional jealousy. We use a case example to highlight important issues in this area.

Adult↗