Insights into a hotspot in the Brasiliensis subcomplex (Hemiptera, Triatominae) by analysis of D2 domain of the nuclear gene 28S.

The Brasiliensis subcomplex is a monophyletic group formed by the species Triatoma brasiliensis brasiliensis, T. b. macromelasoma, T. juazeirensis, T. melanica, and T. sherlocki. However, using cytogenetic data and experimental hybrid crosses, T. lenti and T. petrochiae were also grouped into this subcomplex. This study aims to analyze the properties of hotspot in the D2 domain of the nuclear gene 28S in all species of the Brasiliensis subcomplex as well as T. lenti and T. petrochiae. These species show two transversions at position 385 (G↔C and T↔G). We suggest that this mutation in haplotype 4 may be an initial molecular tool that supports the relationship of these species with the subcomplex. In addition to the transversion at haplotype 4, these species, aside from T. melanica, also possess a transversion at position 385 (G↔T) in haplotype 1. Thus, we describe the hotspot mutations of the D2 domain of the nuclear gene 28S for species in Brasiliensis subcomplex as follows: three transversions are present at position 385 of haplotypes 1 and 4, which are shared by members of the subcomplex as well as T. lenti and T. petrochiae. These transversions may be considered a synapomorphy between these species. However, we emphasize that new phylogenetic studies should be conducted to evaluate whether T. lenti and T. petrochiae are truly members of the Brasiliensis subcomplex.

Distribution of constitutive heterochromatin in species of triatomines with fragmentation of sex chromosomes X.

Cytogenetic analyses of triatomines are considered to be important taxonomic tools. Thus, we analyzed the pattern of constitutive heterochromatin in 7 species of triatomine with fragmentation of the sex chromosome X, focusing on the cytotaxonomy of these triatomines. The species analyzed included Triatoma vitticeps, Triatoma melanocephala, Triatoma tibiamaculata, Triatoma protracta, Meccus pallidipennis, Panstrongylus megistus, and Panstrongylus lignarius. The seminiferous tubules of the adult males were subjected to C-banding. P. megistus and P. lignarius showed differences in chromosome number and disposition of constitutive heterochromatin, as only P. lignarius showed C-blocks in autosomes. C-banding can differentiate these species, since one of the sex chromosome (X) is heterochromatic in T. vitticeps. T. protracta showed C-blocks in both ends of all autosomes, T. tibiamaculata showed terminal C-dots in some autosomal pairs and M. pallidipennis did not show constitutive heterochromatin in autosomes. Thus, we confirmed the heterochromatic pattern of 7 species of insects and emphasized the importance of cytogenetic techniques for C-banding for taxonomy studies of the triatomines, which are important vectors of Chagas disease.

Genetic variability and phylogenetic aspects in species of the genus Macrobrachium.

The genus Macrobrachium includes prawns, which are widely distributed in lakes, floodplains, and rivers in tropical and subtropical regions of South America. This genus presents nearly 210 known species with great ecological and economic importance. However, few studies are related to the biology of these crustaceans. In this study, we analyzed the genetic variability and phylogenetic relationship between Macrobrachium amazonicum and Macrobrachium jelskii, which are closely related species. Additionally, they are syntopics and their taxonomy poses problems because it is difficult to differentiate between the species. We used the mitochondrial gene sequences COI and 16S rRNA to assess the genetic structure of these species in 3 populations that were collected from Tiete hydrographic basin (São Paulo State, Brazil). The interspecific comparison of samples that were collected at the same and different locations showed a low rate of genetic variability. This similarity was attributed to the recent introduction of these species in the regions that were sampled and the habitat conditions in which they inhabit. In addition, these results may be consistent with the hypothesis that they are a single species, interspecific hybrids, or metapopulation. The dendrogram analyses did not reveal the formation of clusters, confirming the disturbances in the genetic structure of the samples that were analyzed in this study. These data are pioneers to these crustaceans, and they confirm the ecological and evolutionary problems between these Macrobrachium species.

Genetic polymorphism, molecular characterization and relatedness of Macrobrachium species (Palaemonidae) based on RAPD-PCR.

The prawn genus Macrobrachium belongs to the family Palaemonidae. Its species are widely distributed in lakes, reservoirs, floodplains, and rivers in tropical and subtropical regions of South America. Globally, the genus Macrobrachium includes nearly 210 known species, many of which have economic and ecological importance. We analyzed three species of this genus (M. jelskii, M. amazonicum and M. brasiliense) using RAPD-PCR to assess their genetic variability, genetic structure and the phylogenetic relationship between them and to look for molecular markers that enable separation of M. jelskii and M. amazonicum, which are closely related syntopic species. Ten different random decamer primers were used for DNA amplification, yielding 182 fragments. Three of these fragments were monomorphic and exclusive to M. amazonicum or M. jelskii and can be used as specific molecular markers to identify and separate these two species. Similarity indices and a phylogenetic tree showed that M. amazonicum and M. jelskii are closest to each other, while M. brasiliense was the most differentiated species among them; this may be attributed to the different habitat conditions to which these species have been submitted. This information will be useful for further studies on these important crustacean species.

Application of PENELOPE code to the efficiency calibration of coaxial germanium detectors.

The code PENELOPE is applied here to the efficiency calibration exercise described in the EUROMET project 428 [Lépy et al., 2001. Appl. Radiat. Isot. 55, 493]. We evaluated the peak efficiencies for a coaxial HPGe detector in the range 60-2000 keV, for point sources located at various distances from the detector and for a cylindrical box containing two different matrixes: a low-density silica and a hydrochloric acid solution. After an optimization of several detector parameters, the results were in good agreement with the experimental values.

Risk factors for Helicobacter pylori infection in children: is education a main determinant?

To investigate potential risk factors associated with Helicobacter pylori (Hp) infection, we performed a case-control study in 167 consecutively selected hospitalized children in Salvador, Brazil. Hp infection was identified by the presence of IgG against Hp in serum samples. Data were gathered using a structured questionnaire, 38.3% children were found to be seropositive and classified as cases, and 61.7% were seronegative controls. After multivariate analysis, independent variables associated with Hp infection included: the educational attainment of the child's provider > or = 11 years (OR 0.1, 95% CI 0.01-0.9), poor garbage disposal service (OR 2.2, 95% CI 1.0-4.9), thumb sucking (OR 4.6, 95% CI 1.1-19.8), brushing teeth more than once a day (OR 5.6, 95% CI 1.8-17.7), having a pet dog (OR 2.5, 95% CI 1.0-6.1), and a history of chronic urticaria (OR 4.0, 95% CI 1.5-10.8). The risk factors identified are consistent with some, but not all, previous studies supporting either oral-oral or faecal-oral transmission of Hp. Our data suggested that a higher educational attainment might play an important role in preventing Hp infection.

[Measles seroprevalence among pediatricians in a teaching hospital]. / Soroprevalência de sarampo entre pediatras de um hospital-escola.

OBJECTIVE: A measles outbreak occurred in S. Paulo state, during 1996 and 1997, resulting in 20,921 cases. Forty seven percent of the cases occurred in people between 20 and 29 years of age, and one of the control strategies of the Department of Health was the vaccination of health care workers. The prevalence of antibodies against measles among the hospital pediatricians was investigated. METHODS: One hundred and fifty samples were taken from volunteer pediatricians to test for measles antibodies using ELISA. A questionnaire about their having had measles and the vaccine was filled out. RESULTS: Of the 150 doctors, 122 (81.4%) were female and 28 (18.6%) male, of between 23 and 46 years of age (mean and median 27 years). The majority (98%-147/150) had protective levels of antibodies against measles (>100 UI/ml); 118 (80.3%-118/147) without and 29 (19.7%-29/147) with a history of measles. Only 3 pediatricians (2%-3/150), had negative serology, 2 without and 1 with a history of measles. Out of the 118 without history of measles, 79 (67%-39/118) in spite of the protective level of antibodies against measles, did not know if they, had been vaccinated. Out of the 79 vaccinated pediatricians, 64 (81%-64/79), had been vaccinated 25 years before, and still maintained protective levels of antibodies. Of the 3 doctors with negative serologies only one declared that he had been vaccinated. CONCLUSIONS: Measles seroprevalence among pediatricians of this hospital is high, especially due to preceding vaccination. On the other hand, the 2% of pediatricians with negative serology, in an epidemic situation could constitute a significant population for the acquisition and dissemination of the disease.

[Subaortic stenosis associated with atrioventricular septal defect. A rarely mentioned condition]. / Estenose subaórtica associada a defeito do septo atrioventricular. Uma condição pouco referida.

White male patient, 14 years old, who developed a severe subaortic stenosis in the late postoperative period of a total correction of atrioventricular septal defect. Clinical diagnosis was confirmed by echocardiography and cardiac catheterization. The patient underwent reoperation for treatment of the new condition, with resection of subaortic stenosis. Atrioventricular septal defects show a narrow and deformed left ventricle outflow tract, susceptible to obstruction before or after operation. It is, therefore, advisable to investigate a possible obstruction before the operation at the operation room and in the late postoperative period.