Biomedical subjects
Publications and source records attributed to Dulce Brito.
Bacteriocin activity can be quantified by a simple parallel line model based on an agar diffusion assay. The quotient between the inhibition zone area and the sensitivity of the indicator bacterium can be used to compare different bacteriocins. Deferred calculations of relative potencies are possible, once purified compounds are obtained.
Hypertrophic cardiomyopathy (HCM) is a relatively common genetic disease, generally with a benign prognosis. However sudden cardiac death may occur, sometimes as the first manifestation of the disease. More than two hundred different mutations have been described in HCM, in 12 different genes encoding sarcomere proteins. This genetic diversity is accompanied by considerable clinical variability and it is likely that phenotype is partially determined by genotype. In recent years it has been suggested that genetic defects could be the major markers of prognosis. Thus, some mutations would carry a good prognosis whereas others, so-called 'malignant' mutations, would be associated with premature sudden death. In a Portuguese population of 35 index patients with HCM the authors found considerable genetic heterogeneity: seven of the 12 mutations identified were de novo, each family having its own 'private' mutation. Moreover, in two unrelated families with the same mutation (I263T--exon 9, missense) in the beta-myosin heavy chain gene (MYH7), penetrance, clinical expression and prognosis were quite different, particularly regarding the occurrence of sudden cardiac death. In two other also unrelated families, in each index patient a different mutation was identified in the troponin I gene (TNNI3): A157V (missense), exon 7 and S199N (missense), exon 8. Phenotypic expression was different but both patients suffered sudden cardiac death (one survived). This suggests that mutations in this gene carry an adverse prognosis. In conclusion, the considerable genetic and clinical variability found in HCM hinders the interpretation of genotype-phenotype correlations, particularly since all the published data is based on small numbers of families.
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BACKGROUND: B-type natriuretic peptide is secreted mainly in the left ventricle in response to elevated wall tension. Plasma levels of the peptide correlate positively with cardiac filling pressures, making it an excellent marker for the presence of left ventricular dysfunction. In hypertrophic cardiomyopathy, enhanced production of B-type natriuretic peptide is observed. However, the relationship of the various structural and functional features present in the disease with the high plasma levels described is not yet fully clarified. In the present study, we prospectively assessed in hypertrophic cardiomyopathy the relationship of plasma NT-proBNP levels with the extent of left ventricular hypertrophy, presence of left ventricular outflow obstruction and echocardiographic parameters of left ventricular diastolic function. METHODS: The study population included 190 individuals: 53 patients with hypertrophic cardiomyopathy and well-preserved left ventricular systolic function (group A), 92 healthy relatives with no disease expression (group B), and an additional group of 46 healthy volunteers (group C) as controls for NT-proBNP levels. Groups A and B were characterized clinically and by echocardiography and compared with each other. Plasma NT-proBNP levels were measured (ECLIA-Elecsys proBNP) and compared in the 3 groups of individuals included in the study. In hypertrophic cardiomyopathy patients, correlation was sought between NT-proBNP levels, NYHA functional class and echocardiographic data. RESULTS: Groups A and B differed (p < 0.001) in septal thickness, maximal wall thickness, left ventricular hypertrophy score, left atrial size, left atrial fractional shortening, derived transmitral filling indices and plasma NT-proBNP levels (group A: 909.9 +/- 1554.2 pg/ml; group B: 40.7 +/- 45.1 pg/ml). Left ventricular diastolic size and pulmonary venous flow velocity-derived indices were similar in the 2 groups. NT-proBNP levels in group B and C (39.4 +/- 34.5 pg/ml) were similar (p = NS). In hypertrophic cardiomyopathy patients, NT-proBNP levels correlate directly with NYHA functional class (r = 0.56, p < 0.001), septal thickness (r = 0.53, p < 0.001), maximal wall thickness (r = 0.59, p < 0.001), left ventricular hypertrophy score (r = 0.63, p < 0.001), left atrial size (r = 0.32, p = 0.023) and mitral deceleration time (r = 0.46, p = 0.001) and inversely with left atrial fractional shortening (r = -0.41, p = 0.005). Functional class also correlates directly with left ventricular hypertrophy score (r = 0.39, p = 0.006), with the most symptomatic patients having the highest scores. CONCLUSIONS: In hypertrophic cardiomyopathy, plasma NT-proBNP levels depend mainly on the severity of left ventricular hypertrophy rather than on the presence of obstruction. Measurement of the peptide may help in the clinical characterization and follow-up of patients with this disease.
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Dilated cardiomyopathy can be idiopathic or be caused by many potentially treatable conditions. We report a complex case of peripartum heart failure associated with hypothyroidism and hypoparathyroidism. Myocardial biopsy suggested that hypothyroidism was the main cause for the dilated pattern, but hypocalcemia played a critical role in acute decompensation of heart failure during hospitalization. After a long and clinically complicated hospital stay, correction of hypothyroidism and hypocalcemia resulted in near-normal cardiac function.
The gene encoding the beta-myosin heavy chain is one of the most frequently implicated in familial hypertrophic cardiomyopathy. Several mutations have been identified and some genotype-phenotype relationships have been assumed, particularly with regard to prognosis. Nevertheless, phenotypic expression is variable even in affected members of the same family carrying the same mutation. We identified the Ile263Thr mutation in several members of two unrelated Portuguese families. Penetrance, clinical behavior and prognosis were quite different between the two families, particularly concerning the occurrence of sudden death. Additional factors probably exist which account for the differences found. The complexity of hypertrophic cardiomyopathy makes it difficult to accurately determine genotype-phenotype relationships, and the screening and comparison of large affected families carrying the same mutation is warranted.
The prevalence of heart failure is increasing all over the world. It is a common and growing public health problem in Portugal as in many other European countries. This article provides a review of health service organization and current heart failure management in Portugal, discusses primary care and ward practices in different hospitals and reports on the use of proven standard therapies for the treatment of heart failure in the community. Despite major advances in diagnosis and treatment, heart failure is only satisfactorily managed. Furthermore efforts are necessary before the beneficial effects observed in trials have a real impact in clinical practice. A broader view and priority for the management of this syndrome on a national level are needed to improve the quality of heart failure care in Portugal.