Alpha thalassemia has not been systematically investigated in Brazil. In this study, 493 unrelated individuals from the southernmost Brazilian state of Rio Grande do Sul were screened for deletional forms of α-thalassemia. One hundred and one individuals had microcytic anemia (MCV < 80 fL) and a normal hemoglobin pattern (Hb A 2 < 3.5% and Hb F < 1%). The subjects were screened for - α3.7 , - α4.2 , - α20.5 , — SEA and — MED deletions but only the - α3.7 allele was detected. The - α3.7 allele frequency in Brazilians of European and African ancestry was 0.02 and 0.12, respectively, whereas in individuals with microcytosis the frequency was 0.20. The prevalence of α-thalassemia was significantly higher in individuals with microcytosis than in healthy individuals (p = 0.001), regardless of their ethnic origin. There were also significant differences in the hematological parameters of individuals with - α3.7 / αα, - α3.7 /- α3.7 and β-thalassemia trait compared to healthy subjects. These data suggest that α-thalassemia is an important cause of microcytosis and mild anemia in Brazilians.
Comparing these results with those obtained in other Brazilian regions, we observe a highly heterogeneous distribution. This knowledge is useful in healthcare planning and allocation of resources, as well as identifying at-risk couples, which will assist with disease prevention.
The increasing number of multidrug-resistant Mycobacterium tuberculosis strains has stimulated the interest of investigators in finding a rapid method for susceptibility testing. We used commercially available rRNA DNA-bioluminescence-labelled probes (Accu-Probe, Gen Probe, Inc. San Diego, Calif.) for this purpose. The study was performed in three chronological steps. (i) We studied the correlation between the photometric light units (PLUs) given by the hybridization method, the numbers of CFU per milliliter, and turbidity as nephelometric units for six different inocula of an M. tuberculosis strain over 14 days. A good correlation (c > 0.9; P < 0.05) was found from the third day for all concentrations used. (ii) Over a period of 14 days we studied the evolution of the PLUs for 20 strains growing in medium with 0.2 l of isoniazid (H) per ml and 18 strains in medium with 1 l of rifampin (R) per ml to standardize the method. Susceptible and resistant strains were used according to the reference proportions method in Middlebrook 7H10, and the MICs were determined in solid and liquid media. The final inoculum of a 10 ؊2 dilution from a McFarland no. 1 standard and reading at 3 and 5 days provided the best results. A quotient was established to find a cutoff point between resistant and susceptible strains. (iii) We used the standardized parameters in 117 tests with H and R. On day 3, the sensitivity, specificity, positive predictive value, and negative predictive value for detecting resistant strains were 86.8, 100, 100, and 90.1%, respectively, and on day 5 they were 96.2, 100, 100, and 94%, respectively. We concluded that the method is readily available, is easy to perform, and could be useful for screening resistant M. tuberculosis strains.
P-glycoprotein (Pgp), the ABCB1 gene product, acts as an efflux pump that transports a large variety of substrates and is a mechanism of cell protection against xenobiotics. An increasing number of studies have shown that some ABCB1 polymorphisms may affect Pgp expression and activity, as well as affecting the development and susceptibility to diseases and pharmacological response. High activity of Pgp has been detected in systemic lupus erythematosus (SLE) patients. The C1236T, G2677T/A, and C3435T are the most commonly studied single nucleotide polymorphisms in the ABCB1 gene. Therefore, their frequencies were determined in Brazilian individuals with European ancestry (N = 143) and in SLE patients (N = 137). Genotyping was performed by PCR-RFLP analysis using specific primers followed by incubation with the appropriate restriction enzymes. The resulting DNA fragments were visualized on agarose or polyacrylamide gels. No statistically significant differences were observed in allelic and genotypic frequencies between SLE and healthy subjects (Fisher exact test). Nevertheless, the 2677A allelic frequency was lower in SLE patients with malar rash (0.007) compared with patients without this feature (0.04; P = 0.0054), while the frequency of this variant was higher in SLE patients with pleuritis (0.07) compared with patients without this feature (0.01; P = 0.0156). We suggest that although the ABCB1 polymorphisms do not directly interfere in SLE susceptibility, their evaluation, especially the 2677A allele, in other immunological processes may be interesting since they can interfere in clinical features of this disease.
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