Cystic fibrosis in a southern Brazilian population: characteristics of 90% of the alleles

Cystic fibrosis (CF) is a genetic disease that frequently leads to death in infancy among Europeans and their descendants. The goals of the present study were to analyze the molecular aspects of CFTR gene characterizing mutations, their frequencies, and the haplotypes formed by four CFTR gene intragenic markers, IVS8-6(T)n, IVS8CA, IVS17bTA and IVS17bCA, in a southern Brazilian population of Caucasian origin. DNA samples from 56 non-related CF patients were analyzed using scanning techniques (single strand conformation polymorphism and denaturing gradient gel electrophoresis), restriction fragment length polymorphism and direct DNA sequencing to identify the mutations. Our results revealed a total of 25 different CF mutations representing nearly 90% of CF alleles, two being novel mutations. Microsatellite haplotypes were defined for CF and normal alleles. The mutational spectrum and the associated haplotypes described for the first time in this study should prove relevant for genetic counselling and CF population screening in Brazil. Moreover, our results suggest the presence of a major Mediterranean component in the contemporary Brazilian CF patient pool.     

Molecular genetics of HMG-CoA lyase deficiency

3-Hydroxy-3-methylglutaryl-CoA lyase (HL) deficiency is a rare autosomal recessive genetic disorder that affects ketogenesis and l-leucine catabolism, which generally appears during the first year of life. Patients with HL deficiency have a reduced capacity to synthesize ketone bodies. The disease is caused by lethal mutations in the HL gene (HMGCL). To date, up to 30 variant alleles (28 mutations and 2 SNPs) in 93 patients have been reported, with a recognizable population-specific mutational spectrum. This disorder is frequent in Saudi Arabia and the Iberian Peninsula (Portugal and Spain), where two mutations (122G>A and 109G>A) have been identified in 87% and 94% of the cases, respectively. In most countries a few patients have a high level of allelic heterogeneity. The mutations are distributed along the gene sequences, although some clustering was observed in exon 2, conforming a possible hot spot. Recently, the crystal structures of the human and two bacterial HL have been published. These experimentally obtained structures confirmed the overall architecture, previously predicted by our group and others using bioinformatic approaches, which shows the (betaalpha)8-barrel structure of the enzyme. In addition, the crystals confirmed the presence of an additional COOH domain containing important structures and residues for enzyme functionality and oligomerization processes. Here, we review all HMGCL mis-sense mutations identified to date, and their implication in enzyme structure and function is discussed. We found that genotype-phenotype correlations are difficult to establish because the evolution of the disease seems more related to the causes of hypoglycaemia (fasting or acute illness) than to a particular genotype.     

Lipoprotein NMB0928 from Neisseria meningitidis serogroup B as a novel vaccine candidate

Polysaccharide-based vaccines for serogroup B Neisseria meningitidis have failed to induce protective immunity. As a result, efforts to develop vaccines for serogroup B meningococcal disease have mostly focused on outer membrane proteins (OMP). Vaccine candidates based on meningococcal OMP have emerged in the form of outer membrane vesicles (OMVs) or, more recently, purified recombinant proteins, as alternative strategies for serogroup B vaccine development. In our group, the protein composition of the Cuban OMVs-based vaccine VA-MENGOC-BC was elucidated using two-dimensional gel electrophoresis and mass spectrometry. The proteomic map of this product allowed the identification of new putative protective proteins not previously reported as components of an antimeningococcal vaccine. In the present study, we have determined the immunogenicity and protective capacity of NMB0928, one of those proteins present in the OMVs. The antigen was obtained as a recombinant protein in Escherichia coli, purified and used to immunize mice. The antiserum produced against the protein was capable to recognize the natural protein in different meningococcal strains by whole-cell ELISA and Western blotting. After immunization, recombinant NMB0928 induced bactericidal antibodies, and when the protein was administered inserted into liposomes, the elicited antibodies were protective in the infant rat model. These results suggest that NMB0928 is a novel antigen worth to be included in a broadly protective meningococcal vaccine.     

The Influence of the growth hormone in the profile of blood pressure. Results in adult patients with deficiency in this hormone

INTRODUCTION AND OBJECTIVES: There is an increasing interest in the relationship between the growth hormone (GH) and the heart since the GH has an important inotropic effect and its use has been tested in patients with severe systolic dysfunction. However, cardiovascular diseases are the main cause of increased morbimortality observed in patients with acromegaly. Growth hormone deficiency has been related to different clinical findings depending on the age of onset. Recent studies have demonstrated that GH deficiency in adults is associated with alterations in blood pressure. The aim of our study was to assess the influence of GH in blood pressure. PATIENTS AND METHODS: We studied 14 adult patients with GH deficiency and 15 healthy subjects, matched for sex and age. The diagnosis of GH deficiency was based on GH response to intravenous insulin tolerance test < 5 ng/ml and IGF-1 levels lower than the normal limit for each age group. In all the patients 24-hour Holter blood pressure monitorization was performed in addition to a treadmill test and echographic evaluation. RESULTS: All patients showed normal systolic and diastolic function in the echocardiographic study. Only one patient had an increased left ventricular mass. Blood pressure was lower in the patients than in the control subjects (p < 0.05). Moreover, the difference remained significant when analysis was based on the time of day. However, the patients showed normal blood pressure response to the effort test with a mean increase of 60%. The length of the exercise on the treadmill test was shorter in the subgroup of GH deficient patients. CONCLUSIONS: Lower systolic blood pressure was observed in GH deficiency patients. The patients studied did not show structural heart alterations. Blood pressure and chronotrophic response to the effort test were similar in both groups.     

Evaluation of lead selection methods for optimal reconstruction of body surface potentials

In this study, several methods for optimal lead selection from multilead electrocardiographic recordings are analyzed. Two different lead selection methods have been implemented. For their evaluation, a linear transformation that reconstructs nonselected leads from selected leads is computed according to the least squares optimization, and the performance is evaluated in terms of the mean square error of the derived potentials and correlation. The algorithms were tested on a database of 72 body surface potential recordings: 18 controls, 18 bundle-branch block, 18 myocardial infarction, and 18 ventricular hypertrophy. Each data set was divided into a study and test subsets. Two experiments were carried out: (1) The lead selection, transformation matrix, and performance evaluation is carried out over the test data set (ideal case), and (2) the lead selection and transformation matrix is carried out over the study data set, but the performance is evaluated over the test data set (real case).Our results show important reconstruction errors with either lead selection methods, and only increasing the number of leads reduces the error in reconstruction. However, if a reduced number of leads are to be selected outside the standard 12-lead electrocardiogram, the method proposed by Lux has been shown to be the best option.     

Age-related variations of fat tissue fraction in normal human bone marrow depend both on size and number of adipocytes: a stereological study

Studies dealing with the number or size of individual adipose cells in human bone marrow are lacking. To ascertain whether the age-related variations in fat tissue fraction depend on the size of individual adipocytes or their number or both, a stereological study of 20 normal human bone marrow specimens was performed. A total number of 17,039 adipose cell profiles was measured and two stereological parameters were obtained in each specimen: mean diameter and number of cells per mm3 of bone marrow. With increasing age, an increasing fat tissue fraction was observed (r = 0.61; p = 0.004). The fat tissue fraction correlated positively with the size (r = 0.81; p less than 0.001) and the number/volume (r = 0.59; p = 0.006) of adipocytes. The significance of both adipocyte size and adipocyte number/volume was confirmed by stepwise multiple regression, in which the size alone explained 66.2% of fat tissue fraction and both size and number/volume explained 97.2% of fat tissue fraction. These results are discussed from a pathophysiological point of view.