The Trypanosoma cruzi Genome Project: Nuclear Karyotype and Gene Mapping of Clone CL Brener

By using improved pulsed field gel electrophoresis conditions, the molecular karyotype of the reference clone CL Brener selected for Trypanosoma cruzi genome project was established. A total of 20 uniform chromosomal bands ranging in size from 0.45 to 3.5 Megabase pairs (Mbp) were resolved in a single run. The weighted sum of the chromosomal bands was approximately 87 Mbp. Chromoblots were hybridized with 39 different homologous probes, 13 of which identified single chromosomes. Several markers showed linkage and four different linkage groups were identified, each comprising two markers. Densitometric analysis suggests that most of the chromosomal bands contain two or more chromosomes representing either homologous chromosomes and/or heterologous chromosomes with similar sizes

Anopheline Species Complexes in Brazil. Current Knowledge of Those Related to Malaria Transmission

A summary of the problems related to the systematics of primary and secondary Brazilian anophelines vectors of malaria is presented.

Evolution of the clinical and epidemiological knowledge about Chagas disease 90 years after its discovery

Three different periods may be considered in the evolution of knowledge about the clinical and epidemiological aspects of Chagas disease since its discovery: (a) early period concerning the studies carried out by Carlos Chagas in Lassance with the collaboration of other investigators of the Manguinhos School. At that time the disease was described and the parasite, transmitters and reservoirs were studied. The coexistence of endemic goiter in the same region generated some confusion about the clinical forms of the disease; (b) second period involving uncertainty and the description of isolated cases, which lasted until the 1940 decade. Many acute cases were described during this period and the disease was recognized in many Latin American countries. Particularly important were the studies of the Argentine Mission of Regional Pathology Studies, which culminated with the description of the Romaña sign in the 1930 decade, facilitating the diagnosis of the early phase of the disease. However, the chronic phase, which was the most important, continued to be difficult to recognize; (c) period of consolidation of knowledge and recognition of the importance of Chagas disease. Studies conducted by Laranja, Dias and Nóbrega in Bambuí updated the description of Chagas heart disease made by Carlos Chagas and Eurico Villela. From then on, the disease was more easily recognized, especially with the emphasis on the use of a serologic diagnosis; (d) period of enlargement of knowledges on the disease. The studies on denervation conducted in Ribeirão Preto by Fritz Köberle starting in the 1950 decade led to a better understanding of the relations between Chagas disease and megaesophagus and other visceral megas detected in endemic areas.

Epidemiology of leishmaniasis in Ecuador: current status of knowledge - A review

Although leishmaniasis is regarded as a significant health problem in Ecuador by the Ministry of Health, and the incidence has increased over the last years, an official map on the geographic distribution of disease and sand fly vectors or a control strategy do not exist yet. This article reviews the current situation based on published information to improve our knowledge and understand the epidemiological situation of leishmaniasis in Ecuador in order to help future research and to develop a national control strategy. The disease is endemic in most provinces throughout Pacific coastal region, Amazonian lowlands, and some inter-Andean valleys with a total 21,805 cases reported during 1990-2003. Whereas cutaneous leishmaniasis (CL) is found throughout Ecuador, mucocutaneous leishmaniasis (MCL) appears to be restricted to the Amazon region; one, parasitologically unconfirmed case of visceral form was reported in 1949. Most human infections are caused by Leishmania (Viannia) spp., which is distributed in the subtropical and tropical lowlands; infections due to L. (Leishmania) spp. are found in the Andean highlands and in the Pacific lowlands as well. The proven vectors are Lutzomyia trapidoi and Lu. ayacuchensis. Canis familiaris, Sciurus vulgaris, Potos flavus, and Tamandua tetradactyla have been found infected with Leishmania spp. It is estimated that around 3000-4500 people may be infected every year, and that 3.1 to 4.5 millions people are estimated to be at risk of contracting leishmaniasis.

The impact of two education methods on knowledge of schistosomiasis transmission and prevention among schoolchildren in a rural community in northern Minas Gerais, Brazil

The objective of this study was to analyse the effect of using two health education approaches on knowledge of transmission and prevention of schistosomiasis of school children living in a rural endemic area in the state of Minas Gerais, Brazil. The 87 children participating in the study were divided into three groups based on gender, age and presence or absence of Schistosoma mansoni infection. In the first group the social representation model and illness experience was used. In the second group, we used the cognitive model based on the transmission of information. The third group, the control group, did not receive any information related to schistosomiasis. Ten meetings were held with all three groups that received a pre-test prior to the beginning of the educational intervention and a post-test after the completion of the program. The results showed that knowledge levels in Group 1 increased significantly during the program in regard to transmission (p = 0.038) and prevention (p = 0.001) of schistosomiasis. Groups 2 and 3 did not show significant increase in knowledge between the two tests. These results indicate that health education models need to consider social representation and illness experience besides scientific knowledge in order to increase knowledge of schistosomiasis transmission and prevention.

Re-mapping the molecular features of the human immunodeficiency virus type 1 and human T-cell lymphotropic virus type 1 Brazilian sequences using a bioinformatics unit established in Salvador, Bahia, Brazil, to give support to the viral epidemiology studies

The analysis of genetic data for human immunodeficiency virus type 1 (HIV-1) and human T-cell lymphotropic virus type 1 (HTLV-1) is essential to improve treatment and public health strategies as well as to select strains for vaccine programs. However, the analysis of large quantities of genetic data requires collaborative efforts in bioinformatics, computer biology, molecular biology, evolution, and medical science. The objective of this study was to review and improve the molecular epidemiology of HIV-1 and HTLV-1 viruses isolated in Brazil using bioinformatic tools available in the Laboratório Avançado de Sáude Pública (Lasp) bioinformatics unit. The analysis of HIV-1 isolates confirmed a heterogeneous distribution of the viral genotypes circulating in the country. The Brazilian HIV-1 epidemic is characterized by the presence of multiple subtypes (B, F1, C) and B/F1 recombinant virus while, on the other hand, most of the HTLV-1 sequences were classified as Transcontinental subgroup of the Cosmopolitan subtype. Despite the high variation among HIV-1 subtypes, protein glycosylation and phosphorylation domains were conserved in the pol, gag, and env genes of the Brazilian HIV-1 strains suggesting constraints in the HIV-1 evolution process. As expected, the functional protein sites were highly conservative in the HTLV-1 env gene sequences. Furthermore, the presence of these functional sites in HIV-1 and HTLV-1 strains could help in the development of vaccines that pre-empt the viral escape process.

Analysis and chromosomal mapping of Leishmania (Leishmania) amazonensis amastigote expressed sequence tags

The characterization of expressed sequence tags (ESTs) generated from a cDNA library of Leishmania (Leishmania) amazonensis amastigotes is described. The sequencing of 93 clones generated new L. (L.) amazonensis ESTs from which 32% are not related to any other sequences in database and 68% presented significant similarities to known genes. The chromosome localization of some L. (L.) amazonensis ESTs was also determined in L. (L.) amazonensis and L. (L.) major. The characterization of these ESTs is suitable for the genome physical mapping, as well as for the identification of genes encoding cysteine proteinases implicated with protective immune responses in leishmaniasis.

Mapping the molecular characteristics of Brazilian human T-cell lymphotropic virus type 1 Env (gp46) and Pol amino acid sequences for vaccine design

This study was carried out to evaluate the molecular pattern of all available Brazilian human T-cell lymphotropic virus type 1 Env (n = 15) and Pol (n = 43) nucleotide sequences via epitope prediction, physico-chemical analysis, and protein potential sites identification, giving support to the Brazilian AIDS vaccine program. In 12 previously described peptides of the Env sequences we found 12 epitopes, while in 4 peptides of the Pol sequences we found 4 epitopes. The total variation on the amino acid composition was 9 and 17% for human leukocyte antigen (HLA) class I and class II Env epitopes, respectively. After analyzing the Pol sequences, results revealed a total amino acid variation of 0.75% for HLA-I and HLA-II epitopes. In 5 of the 12 Env epitopes the physico-chemical analysis demonstrated that the mutations magnified the antigenicity profile. The potential protein domain analysis of Env sequences showed the loss of a CK-2 phosphorylation site caused by D197N mutation in one epitope, and a N-glycosylation site caused by S246Y and V247I mutations in another epitope. Besides, the analysis of selection pressure have found 8 positive selected sites (w = 9.59) using the codon-based substitution models and maximum-likelihood methods. These studies underscore the importance of this Env region for the virus fitness, for the host immune response and, therefore, for the development of vaccine candidates.

Aedes aegypti, Aedes albopictus, and dengue in Argentina: current knowledge and future directions

Since the reinfestation of South American countries by Ae. aegypti, dengue fever (DF) and dengue hemorrhagic fever (DHF) have become a major public health concern. The aim of this paper was to review the information related with Aedes vectors and dengue in Argentina since the reintroduction of Ae. aegypti in 1986. The geographic distribution of Ae. albopictus is restricted to the Northeast, and that of Ae. aegypti has expanded towards the South and the West in comparison with the records during the eradication campaign in the 1960s. Since 1998, 4,718 DF cases have been reported concentrated in the provinces of Salta, Formosa, Misiones, Jujuy and Corrientes. Despite the circulation of three dengue virus serotypes (DENV-1, -2 and -3) in the North of the country, DHF has not occurred until the present. The information published over the last two decades regarding mosquito abundance, temporal variations, habitat characteristics, competition, and chemical and biological control, was reviewed. Considering the available information, issues pending in Argentina are discussed. The presence of three DENV, the potential spread of Ae. albopictus, and the predicted climate change suggest that dengue situation will get worse in the region. Research efforts should be increased in the Northern provinces, where DHF is currently an actual risk.

Brazilian contribution for a better knowledge on the biology of Toxoplasma gondii

Historically, scientists in Brazil has significantly contributed to the biology, cultivation and structural organization of the pathogenic protozoan Toxoplasma gondiiand its interaction with host cells, starting with the description of the protozoan by Splendore in 1908. The intracellular and extracellular corpuscoli observed in rabbits, corresponded to what we now as tachyzoites. Later on, a pioneering method to grow T. gondii in tissue cultures was developed by Guimarães and Meyer, 1942. They also observed for the first time T. gondii by transmission electron microscopy and made the initial description of the cytoskeleton of T. gondii by observing negatively stained cells. In the 1980's, the relation of the cytoskeleton with the sub-pellicular microtubules was reveled by freeze-fracture. More recently, several Brazilian groups have analyzed in detail basic aspects of the early interaction of the protozoan with the host cell, such as the role of protein phosphorylation, transfer of host cell surface components to the protozoan and genesis and organization of the parasitophorous vacuole. Tachyzoites strategically inhibit nitric oxide production during active invasion of activated macrophages. In vitro studies on the sexual cycle of T. gondii using primary cultures of cat enterocytes and the egress from host cells are being carried out. Perspectives are that the contribution of Brazilian science to the knowledge on T. gondii biology will continue to flourish in years to come.

Schistosomiasis risk mapping in the state of Minas Gerais, Brazil, using a decision tree approach, remote sensing data and sociological indicators

Schistosomiasis mansoni is not just a physical disease, but is related to social and behavioural factors as well. Snails of the Biomphalaria genus are an intermediate host for Schistosoma mansoni and infect humans through water. The objective of this study is to classify the risk of schistosomiasis in the state of Minas Gerais (MG). We focus on socioeconomic and demographic features, basic sanitation features, the presence of accumulated water bodies, dense vegetation in the summer and winter seasons and related terrain characteristics. We draw on the decision tree approach to infection risk modelling and mapping. The model robustness was properly verified. The main variables that were selected by the procedure included the terrain's water accumulation capacity, temperature extremes and the Human Development Index. In addition, the model was used to generate two maps, one that included risk classification for the entire of MG and another that included classification errors. The resulting map was 62.9% accurate.

Relationships and knowledge in the firm internationalization process

Based on the variables relationship and knowledge, this article aimed at analyzing how a multinational enterprise selects an entry mode to operate in a particular international market and how this initial choice evolves over time. We devised a rather new theoretical framework to address it by combining three theoretical approaches that have dealt with the firm internationalization: the Uppsala model, the relational approach, and the subsidiary development literature. We constructed a qualitative backward-looking longitudinal case study of the internationalization process of a North-American multinational enterprise in the Brazilian market. Results show that four types of relationships and three types of knowledge played the role in the events that characterized the internationalization of this firm. Based on these results, five new hypotheses concerning the interplay between relationships and knowledge in the internationalization process of the firm are suggested for future empirical tests.

Knowledge and attitude regarding standard precautions in a Brazilian public emergency service: a cross-sectional study

The purpose of this study was to assess the knowledge and attitude of health care professionals regarding their use of universal precaution measures at a public emergency service. The study also aimed to assess the rates of occupational accidents involving biological substances among those workers. This study was performed with 238 workers, from June to November 2006, using univariate and multivariate analysis. The chance of not adopting precaution measures was 20.7 (95% CI: 5.68 - 75.14) times greater among drivers compared to physicians. No significant association was found between adopting universal precaution measures. The occupational accident rate was 20.6% (40.8% involving sharp-edged objects). The risk of physicians having an occupational accident was 2.7(95% CI: 1.05 - 7.09) times higher than that of drivers. The fact that a staff member had adequate knowledge about universal precaution measures was insufficient to foster compatible attitudes towards reducing the risk of transmitting infectious agents and causing occupational accidents.

Knowledge as a factor in vulnerability to tuberculosis among nursing students and professionals

The objective of this study was to identify vulnerability to tuberculosis (TB) related to knowledge about the disease among 76 nursing students and professionals. A quantitative descriptive study was conducted using a closed questionnaire for the collection of data regarding transmission, preventive and biosafety measures, diagnosis, and prejudice regarding the disease. The SAS software version 9.1.3 was used for data analysis, with the level of significance set at 5% (p < 0.05). Nursing students and professionals showed a vulnerability to TB related to knowledge about transmission, preventive and biosafety measures, and diagnosis of the disease. With respect to transmission, vulnerability was higher among nursing professionals. The results indicate the need for investment by healthcare institutions surrounding this topic in view of the important role of nursing in the establishment of strategies for prevention and control of the disease.