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Biomedical subjects

A A Lopes

Publications and source records attributed to A A Lopes.

At least 37 records · Page 2Linked to original sources
PubMed2000

Prognostic factors of rheumatic mitral stenosis during pregnancy and puerperium.

OBJECTIVE: To identify characteristics associated with complications during pregnancy and puerperium in patients with rheumatic mitral stenosis. METHODS: Forty-one pregnant women (forty-five pregnancies) with mitral stenosis, followed-up from 1991 to 1999 were retrospectively evaluated. PREDICTOR VARIABLES: the mitral valve area (MVA), measured by echocardiogram, and functional class (FC) before pregnancy (NYHA criteria). Maternal events: progression of heart failure, need for cardiac surgery or balloon mitral valvulotomy, death, and thromboembolism. Fetal/neonatal events: abortion, fetal or neonatal death, prematurity or low birth weight (<2,500 g), and extended stay in the nursery or hospitalization in newborn ICU. RESULTS: The mean +/- SD of age of the patients was 28.8+/-4.6 years. The eventful and uneventful patients were similar in age and percentage of first pregnancies. As compared with the level 1 MVA, the relative risk (RR) of maternal events was 5.5 (95% confidence interval (CI) =0.8-39.7) for level 2 MVA and 11.4 (95% CI=1.7-74.5) for level 3 MVA. The prepregnancy FC (FC > or = II and III versus I) was also associated with risk for maternal events (RR=2.7; 95% CI=1.4-5.3).MVA and FC were not importantly associated with these events, although a smaller frequency of fetal/neonatal events was observed in patients who had undergone balloon valvulotomy. CONCLUSION: In pregnant women with mitral stenosis, the MVA and the FC are strongly associated with maternal complications but are not associated with fetal/neonatal events. Balloon mitral valvulotomy could have contributed to reducing the risks of fetal/neonatal events in the more symptomatic patients who had to undergo this procedure during pregnancy.

Adult↗
PubMed2000

Histoplasmosis presenting as acute respiratory distress syndrome after exposure to bat feces in a home basement.

This report describes the clinical and epidemiological findings of an outbreak of histoplasmosis in Brazil involving four persons of the same family, one adult and three children. Contamination by fecal material of bats in the basement of the house was found to be the most likely cause of this outbreak. None of the patients had evidence of immune deficiency. The adult died of acute respiratory distress syndrome. A more severe presentation of the disease in this patient may be partly explained by a heavier exposure to the feces of bats.

Adult↗
PubMed2000

Decreased sialic acid content of plasma von Willebrand factor in precapillary pulmonary hypertension.

In pulmonary hypertension, defective von Willebrand factor protein (vWF) lacking large multimers is present in circulation. This is associated with evidence of chronic endogenous platelet activation. Since asialo vWF has been shown to promote platelet activation and aggregation, we decided to investigate possible changes in the sialic acid content of plasma vWF in patients with precapillary pulmonary hypertension. vWF-associated sialic acid was measured indirectly as a wheat germ agglutinin-reactive substance (WGA-RS, Western blotting), and directly, as a thiobarbituric acid-reactive substance (TBA-RS, spectrophotometric reading). In the sixteen patients we studied (ages 8-45 yr), circulating vWF concentration was 2.18 times normal (p <0.001). However, patient vWF subunit contained 19% (WGA-RS) to 24% (TBA-RS) less sialic acid than the normal protein (p <0.05 for both determinations). In five patients, vWF-associated sialic acid was below 50% normal. We conclude that circulating vWF is hyposialylated in precapillary pulmonary hypertension and speculate that this might influence its interaction with platelets in vivo in these patients.

Adolescent↗
PubMed1999

Cytoskeletal organization and incorporation of beta 3 integrin in thrombin-stimulated platelets: effect of acetylsalicylic acid.

Platelet stimulation by agonists is followed by changes in cytoskeletal organization that includes actin polymerization and association of the membrane skeleton (which is connected with the integrin alpha IIb beta 3) with the underlying cytoplasmic actin filaments. The effect of orally administered acetylsalicylic acid to healthy volunteers on incorporation of contractile protein and beta 3 integrin into the cytoskeletal core of thrombin-stimulated platelets was studied. Stimulation was followed by increased contractile protein and beta 3 incorporation into the cytoskeleton. Acetylsalicylic acid intake resulted in decreased incorporation of myosin and actin (32% and 20%, respectively), and a decrease (36%) in the association of beta 3 integrin with the cytoskeletal elements was evident. In conclusion, we have shown that acetylsalicylic acid, besides the known inhibitory effect on thromboxane synthesis, promotes changes in the cytoskeletal organization of thrombin-stimulated platelets that could limit thrombus formation.

Actinin↗
PubMed1999

Difference in the in-hospital mortality of unstable angina pectoris between men and women.

PURPOSE: To assess differences in the in-hospital mortality (HM) rate between men and women with unstable angina pectoris (UA) according to age, depression of the ST segment, history of previous acute myocardial infarction (AMI), and risk factors for coronary heart disease. METHODS: From October 96 to March 98, 261 patients with UA were selected. Logistic regression models were developed to adjust the association between sex and HM for possible influence of covariables, such as hypertension, diabetes mellitus, dyslipidemia, sedentary lifestyle, smoking, and familial history of early coronary heart disease. RESULTS: HM due to UA was approximately three times higher in women (9.3%; 12/129) than in men (3.0%; 4/132) accounting for a relative risk of 3.07; 95% confidence interval (CI) = 1.02-9.27. In logistic regression models, the association between sex and death was not significantly altered when the following parameters were considered: age, depression of the ST segment, history of previous AMI and risk factors for coronary heart disease. The nonadjusted and adjusted odds ratio (OR) for the distinct covariables were 3.28 (CI 95% = 1.03-10.45) and 3.14 (CI = 95% = 0.88-11.20), respectively. CONCLUSION: Similarly to AMI, HM in UA is higher in women than in men. Age, risk factors for coronary heart disease, and depression of the ST segment in the electrocardiogram on patients' admission to the hospital did not significantly influence the association between sex and death.

Angina Pectoris↗
PubMed1998

Severe cat flea infestation of dairy calves in Brazil.

An investigation was conducted into a severe flea infestation on dairy calves. Inspection of the dairy revealed a high infestation of Ctenocephalides felis felis on four calves and thousands of fleas in the stable where cows and calves were brought in for milking. A 3-month-old female calf was highly infested with fleas. The animal showed an evident lethargy, weight loss, as well as pale mucous membranes and dehydration. Hematological analysis revealed anemia, with 10% packed cell volume and a 1.72 x 10(6) microl(-1) erythrocyte count. Blood transfusions were performed and the flea infestation was controlled with 1% fipronil pour-on (1 ml/10 kg). The farmer was advised to treat the other calves with fipronil, remove the manure from the stable and spread 1% propoxur powder (100 g/m2) onto the floor of the stable.

Animal Husbandry↗
PubMed1998

Abnormalities in circulating von Willebrand factor and survival in pulmonary hypertension.

BACKGROUND: Changes in circulating von Willebrand factor (vWF) have been widely used for evaluating the severity of endothelial dysfunction in vascular disorders. In pulmonary hypertension, quantitative and structural abnormalities in circulating von Willebrand factor have been identified. We therefore hypothesized that these abnormalities could have prognostic implications. PATIENTS AND METHODS: We studied 30 consecutive medically treated patients with primary (n = 11) or secondary precapillary pulmonary hypertension associated with congenital heart disease (n = 16) or schistosomiasis (n = 3). Plasma antigenic activity of vWF (vWF:Ag) was measured by electroimmunodiffusion. The relative concentration of low molecular weight vWF multimers (vWF:LMW/Total) was determined by Western immunoblotting. Results of initial evaluation were analyzed at the end of the first and third years of follow-up. RESULTS: Baseline vWF:Ag activity (P <0.0002) and the vWF: LMW/Total ratio (P <0.005) were higher in patients who died during the first year than in survivors. All patients with vWF:Ag activity >250% or a vWF:LMW/Total ratio >70% died in the first year. All 7 patients with vWF:Ag activity <100% were alive at the end of 3 years of follow-up. A vWF:LMW/Total ratio >68% was 67% sensitive and 95% specific for 1-year mortality, with an overall predictive value of 80%. Both vWF:Ag levels and mortality were greater in the patients with primary pulmonary hypertension than in patients with secondary pulmonary hypertension. CONCLUSION: Patients with pulmonary hypertension who have abnormalities in circulating vWF have reduced 1-year survival. This might affect decisions such as patient assignment to lung transplantation.

Adolescent↗
PubMed1998

Stimulation of human smooth muscle cell proliferation by thrombin involves increased synthesis of platelet-derived growth factor.

OBJECTIVES: Thrombin generated at sites of vascular injury not only participates in the coagulation cascade but can also signal other events related to cell mitogenesis and migration. In this report, we investigated the effects of thrombin on the proliferation of human arterial smooth muscle cells (SMCs) in culture and its interaction with platelet-derived growth factor (PDGF). MATERIAL AND METHODS: Human arterial SMCs originated from a renal artery were grown in cell culture. The effect of thrombin on DNA synthesis was evaluated by 3H-thymidine incorporation. The effect of thrombin on inositol-phosphate formation by SMCs was also analyzed as well as the binding of PDGF AA and BB to these cells. PDGF secretion was analyzed by radioimmunoassay (RIA). RESULTS: Exposure of cultured human SMCs to thrombin caused an increased rate of DNA synthesis in a dose-response manner, with a maximal stimulatory effect at a concentration of 2.0 U/mL. Thrombin was found to increase the accumulation of inositol phosphates and to increase the production of PDGF as measured by RIA. Exposure of cells to 2.0 U/mL thrombin resulted in a strong decrease in PDGF AA binding to PDGF receptors and did not change PDGF BB binding, probably indicating that PDGF alpha-receptors could be occupied by endogenously produced PDGF A. CONCLUSION: Thrombin stimulates human vascular SMC proliferation in a dose-response way, in part by the formation of inositol phosphates. The mechanism responsible for this effect involves, at least in part, an increased endogenous synthesis of PDGF.

Anticoagulants↗
PubMed1998

Circulating von Willebrand factor antigen as a predictor of short-term prognosis in pulmonary hypertension.

STUDY OBJECTIVE: To determine the potential value of plasma von Willebrand factor antigenic activity (vWF:Ag) and other commonly measured clinical variables for predicting which patients with precapillary pulmonary hypertension would be unlikely to survive 1 year. DESIGN: Prospective clinical study. The data obtained at the beginning of the study were analyzed at the end of the first year of follow-up. PATIENTS AND METHODS: Forty patients aged 1.2 to 45 years (median, 24 years) entered the study. Eleven patients had primary pulmonary hypertension, and in the remaining ones, pulmonary vascular disease was associated with antiphospholipid syndrome (n = 1), collagen vascular disease (n = 1), schistosomiasis (n = 3), or congenital heart defects (Eisenmenger's syndrome) (n = 24). Plasma vWF:Ag was determined by electroimmunodiffusion, and the results were expressed as the percentage of activity. RESULTS: Seven of 11 patients with primary pulmonary hypertension but only 4 of 29 patients with secondary pulmonary hypertension died during the follow-up period (p < 0.005). Initial vWF:Ag values were significantly higher in the nonsurvivor group in comparison with the survivors (256.6+/-85.3% and 132.0+/-59.3% activity, respectively; p < 0.0001). The likelihood of fatal outcome as a function of plasma vWF:Ag levels was estimated for primary and secondary pulmonary hypertensive patients using logistic regression analysis. Decreased life expectancy was significantly related to high vWF:Ag levels and an established diagnosis of primary pulmonary hypertension. A plasma vWF:Ag of >240% (p = 0.003) was 54% sensitive and 93% specific for identifying patients who were unlikely to survive 1 year, with an overall predictive value of 75%. No other variables correlated significantly with survival. CONCLUSION: Plasma vWF:Ag seems to be a useful biochemical index for predicting short-term prognosis in patients with pulmonary hypertension. In contrast to hemodynamic and histopathological predictors of survival, vWF:Ag does not require invasive techniques to be determined. In light of the possibility of false-negative results, serial measurements should be performed over time in patients with vWF:Ag of <240%. This observation proved helpful in two patients in this study.

Adolescent↗
PubMed1998

[Von Willebrand factor and pulmonary endothelial dysfunction. Prognostic implications].

PURPOSE: To analyze quantitative and structural changes in circulating von Willebrand factor (vWF) in 40 precapillary pulmonary hypertensive patients, as an attempt to identify possible correlations between endothelial cell dysfunction and patient short-term (one year) survival. METHODS: Plasma antigenic activity of vWF (vWF:Ag) was analyzed by immunoelectrophoresis. The relative concentration of vWF low molecular weight multimers (LMWM%) and the composition of vWF subunit were determined by densitometric analysis of Western blots. RESULTS: vWF:Ag was importantly increased in patients in comparison with normals (p < 0.001). Patients also had increased LMWM% (p < 0.001) and increased degradation of vWF main subunit (p < 0.05). At the beginning of the study, nonsurvivors (N = 11) had higher vWF:Ag (p < 0.001) and LMWM% (p < 0.005) values in comparison with survivors. LMWM% was selected by logistic regression analysis as a predictor of death during the first year of follow-up (p < 0.05). CONCLUSION: Marked changes in circulating vWF likely reflect extensive pulmonary vascular endothelial cell dysfunction and are associated with poor short-term prognosis in pulmonary hypertension.

Adolescent↗
PubMed1998

[Why is the in-hospital case-fatality rate of acute myocardial infarction higher in women?].

PURPOSE: To assess the influence of age, disease severity at admission and therapeutic interventions on the higher in-hospital case-fatality rate of acute myocardial infarction (MI) in women. METHODS: A retrospective cohort study involving a total of 388 acute MI patients (50 deaths). The following variables were treated as possible explanatory factors for the association between gender and case-fatality rate of acute MI: age (< 60 vs > or = 60 years), duration of symptoms, Killip class, type of infarction (Q wave vs non-wave), comorbidities, previous history of stroke and specific therapeutic interventions for acute MI (aspirin, beta-blocking drugs, and thrombolytic agents). Logistic regression models were used to assess the influence of potential confounders on the association between gender and in-hospital death. RESULTS: The in-hospital case-fatality rate of acute MI was higher in women (19.5% vs 9.4%) than in men (odds ratio (OR) = 2.34; 95% CI = 1.12-4.47). Although women were significantly older than men (p < 0.01), the association between gender and death was reduced only by 15 percent after adjusting for age (OR = 1.99; 95% CI = 1.07-3.67). This association became weaker after taking into account disease severity at admission (OR = 1.84; 95% CI = 0.90-3.74) and therapeutic interventions for acute MI (OR = 1.50; 95% CI = 0.67-3.38). CONCLUSION: Differences in age cannot fully explain the higher case-fatality rate in women than in men with acute MI. Severity of disease at admission and differences in therapeutic interventions might play an important role in the higher case-fatality rate of acute MI among women.

Age Factors↗
PubMed1998

[Difference of hospital mortality of acute myocardial infarction between men and women treated with primary angioplasty].

PURPOSE: To compare the in-hospital case-fatality rate of men and women submitted to percutaneous transluminal coronary angioplasty (PTCA) as a strategy of reperfusion in acute myocardial infarction (MI). METHODS: A retrospective cohort study based on information abstracted from medical records of MI patients admitted to a hospital where PTCA is used as the preferred method for early myocardial reperfusion. A total of 83 patients, 35 (42%) women and 48 (58%) men, who met the criteria for early myocardial reperfusion was included in the analysis. RESULTS: The mean age of women was higher than that of men (66 +/- 10 vs 58 +/- 11 years; p < 0.001). The women also had a higher frequency of diabetes mellitus (37.1% vs 6.4%; p < 0.001). Despite these differences in age and in the frequency of diabetes mellitus, the percentage of patients in whom the PTCA was considered successful was similar between men (83.3%) and women (82.3%). The case-fatality rate was also similar between men and women; 14.6% and 14.3%, respectively. CONCLUSION: The possibility that the excess risk of death in women with MI may be reduced and even eliminated with the use of PTCA, supports to the need for the development of a clinical trial to assess this question.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Ratio of proportions and the use of the delta method for confidence intervals in logistic regression].

OBJECTIVE: To present an application of logistic regression modelling to estimate ratios of proportions, such as prevalence ratio or relative risk, and the Delta Method to estimate confidence intervals. METHOD: The Delta Method was used because it is appropriate for the estimation of variance of non-linear functions of random variables. The method is based on Taylor's series expansion and provides a good approximation of variance estimates. A computer program, utilizing the matrix module of SAS, was developed to compute the variance estimates. A practical demonstration is presented with data from a cross-sectional study carried out on a sample of 611 women, to test the hypothesis that the lack of housework sharing is associated with high scores of psychological symptoms as measured by a validated questionnaire. RESULTS: Crude and adjusted prevalence ratio estimated by logistic regression were similar to those estimated by tabular analysis. Also, ranges of the confidence intervals of the prevalence ratio according to the Delta Method were nearly equal to those obtained by the Mantel-Haenszel approach. CONCLUSIONS: The results give support to the use of the Delta Method for the estimation of confidence intervals for ratios of proportions. The method should be seen as an alternative for situations in which the need to control a large number of potential confounders limits the use of stratified analysis.

Confidence Intervals↗
PubMed1997

[Predictors of hospital mortality in the thrombolytic era for acute myocardial infarction in Salvador, State of Bahia, Brazil].

PURPOSE: To determine the cumulative incidence and risk factors of in-hospital death due to acute myocardial infarction (AMI) in the thrombolytic era and to assess the degree of incorporation of new therapeutical interventions to the treatment of AMI in Salvador, Brazil. METHODS: A retrospective study based on medical records of 388 patients hospitalized with an AMI in different hospitals between January 1993 and December 1994. The relative risk (RR) was used as a measure of association for the unadjusted analysis. To control for possible confoundears and to assess interactions, odds ratios (OR) were used to estimate the RR, by logistic regression models. RESULTS: During the hospitalization period 50 (12.9%) patients died. The main predictors of hospital mortality in the unadjusted comparisons were older age (age > 60 years) (RR = 2.76; p < 0.01), female gender (RR = 2.08; p = 0.01), Killip class > 1 (RR = 5.73; p < 0.01), anterior wall AMI (RR = 1.92; p = 0.02), previous stroke (RR = 4.13; p < 0.01) and systemic disease (RR = 2.76; p < 0.01). In the multivariate analysis, older age (OR = 2.42; p = 0.02), Killip class > 1 (OR = 7.14; p < 0.01), anterior wall AMI (RR = 2.37; p = 0.02) and previous stroke (RR = 2.34; p = 0.04) were the main independent predictors of hospital death. Thrombolytic therapy was used in 143 patients (36.8%), aspirin in 322 (83%), beta blockers in 204 (52.6%) and heparin in 248 (63.9%). Cardiogenic shock was responsible for more than half of the death cases. CONCLUSION: Based on the data presented, older age, Killip class and anterior wall infarction are still important predictors of death due to AMI in the thrombolytic era, confirming other studies.

Aged↗