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O Fernandes

Publications and source records attributed to O Fernandes.

At least 37 records · Page 2Linked to original sources
PubMed1999

Leishmania (Viannia) braziliensis is the predominant species infecting patients with American cutaneous leishmaniasis in the State of Minas Gerais, Southeast Brazil.

Skin biopsies from 53 patients with American cutaneous leishmaniasis (ACL) from the State of Minas Gerais, Brazil, were used for a characterization of the Leishmania parasites. A pair of primers flanking the conserved region of the Leishmania minicircle kDNA was used to obtain amplified DNA via the polymerase chain reaction. The amplified products were subsequently hybridized with Leishmania subgenus-specific radiolabeled probes. Parasites from 49 out of 53 samples (92.5%) were characterized as belonging to the subgenus Viannia and four (7.5%) as belonging to the subgenus Leishmania. Clinical, epidemiological and molecular evidence allow us to conclude that Leishmania (V.) braziliensis and Leishmania (L.) amazonensis are the species present in the patients studied and that L. (V.) braziliensis is the predominant species in the State of Minas Gerais, Brazil.

Adolescent↗
PubMed1999

The complexity of the sylvatic cycle of Trypanosoma cruzi in Rio de Janeiro state (Brazil) revealed by the non-transcribed spacer of the mini-exon gene.

American trypanosamiasis occurs in nature as a sylvatic cycle, where Trypanosoma cruzi interacts with wild triatomines and mammalian reservoirs, such as marsupials, rodents, armadillos and other animals. Due to difficulties in trying to isolate T. cruzi stocks from the sylvatic cycle, very few studies have been performed in order to understand the parasite infection in natural environments. Traditionally T. cruzi has been considered to be composed of a highly heterogeneous population of parasites. In contrast, the mini-exon and the 24S alpha rRNA gene loci have shown that T. cruzi stocks can be clustered in 2 major phylogenetic groups: lineage 1 and lineage 2. In this report, 68 recently isolated T. cruzi samples from the sylvatic cycle belonging to different geographical areas in Rio de Janeiro, Brazil, have been typed based on a variable spot in the non-transcribed spacer of the mini-exon gene. Eight isolates were from triatomines, 26 stocks were from golden-lion tamarins, 31 from opossums, 2 from rodents and 1 from a three-toed sloth. Thirty (44%-30/68) isolates were typed as lineage 1, while 36 (53%-36/68) isolates were typed as lineage 2. Two opossums presented mixed infection. Therefore, 3% (2/68) of the isolates were typed as lineage 1 + lineage 2. Using these geographical regions as models of sylvatic environments, it was observed that 96% of the Didelphis marsupialis were infected by lineage 2 isolates, while all 26 golden-lion tamarins were infected by lineage 1. The results show preferential association of the 2 lineages of T. cruzi with different hosts, composing the complexity of the sylvatic cycle.

Animals↗
PubMed1999

Use of PCR in diagnosis of human american tegumentary leishmaniasis in Rio de Janeiro, Brazil.

In Brazil, the most common etiological agent of American tegumentary leishmaniasis is Leishmania (Viannia) braziliensis. In general, diagnostic techniques envisage the visualization of the parasite, but that technique has a low sensitivity. The main purpose of the present work was to evaluate the PCR as a routine tool for the diagnosis of leishmaniasis. Biopsy specimens from cutaneous or mucosal lesions were taken from 230 individuals from areas where Leishmania is endemic: 216 patients who had a clinical picture suggestive of leishmaniasis and 14 individuals with cutaneous lesions due to other causes. Each specimen was processed for histopathologic examination, culture, touch preparation, and DNA isolation. Oligonucleotides that amplify the conserved region of the minicircle molecules of Leishmania were used in a hot-start PCR. While at least one conventional technique was positive for Leishmania for 62% (134 of 216) of the patients, PCR coupled to hybridization was positive for 94% (203 of 216) of the patients. The 14 patients whose clinical picture was not suggestive of leishmaniasis had negative results by all techniques. The impact of the PCR was striking in mucosal disease. While the disease in only 17% (4 of 24) of the patients could be diagnosed by conventional techniques, PCR was positive for 71% (17 of 24) of the patients. Hybridization showed that all cases of disease were caused by parasites belonging to the Viannia subgenus. Altogether, the results indicate that PCR is a valuable tool for the diagnosis of leishmaniasis on a routine basis and is likely to provide valuable epidemiological information about the disease in countries where it is endemic.

Animals↗
PubMed1999

Chagas disease: from bush to huts and houses. Is it the case of the Brazilian Amazon?

Two of the major problems facing the Amazon - human migration from the other areas and uncontrolled deforestation - constitute the greatest risk for the establishment of endemic Chagas disease in this part of Brazil. At least 18 species of triatomines had been found in the Brazilian Amazon, 10 of them infected with Trypanosoma cruzi, associated with numerous wild reservoirs. With wide-range deforestation, wild animals will perforce be driven into other areas, with tendency for triatomines to become adapted to alternative food sources in peri and intradomicilies. Serological surveys and cross-sectional studies for Chagas disease, carried out in rural areas of the Rio Negro, in the Brazilian Amazon, showed a high level of seropositivity for T. cruzi antibodies. A strong correlation of seroreactivity with the contact of gatherers of piaçava fibers with wild triatomines could be evidenced.

Adolescent↗
PubMed1999

Cystic fibrosis: low frequency of DF508 mutation in 2 population samples from Rio de Janeiro, Brazil.

Blood samples from 44 unrelated cystic fibrosis (CF) patients from Rio de Janeiro, Brazil, were analyzed for the 8 European CF mutations. Six homozygous and 15 heterozygous carriers of the DF508 mutation were found, corresponding to 47.7% of CF patients (allele frequency 0.3068). The G542X and G551D mutations were also observed with allele frequencies of 0.0227 and 0.0114, respectively. An analysis of the DF508 mutation in 291 randomly chosen, healthy individuals was performed, and only 3 heterozygous carriers were identified. These results show that the frequency of the DF508 allele in Rio de Janeiro is much lower than the world average; this may be due to the extremely heterogeneous ethnic admixture of the study population. By combining the results of these 2 different samples (CF patients and random population) and admixture data from Rio de Janeiro, we can estimate the CF incidence in this population to be 1:3542 individuals. However, taking into account the Rio de Janeiro ethnic admixture, we can find an estimate of 1:6902 individuals.

Brazil↗
PubMed1999

Minicircle variable region probes for characterization of Leishmania (Viannia) species.

The minicircle molecules present in the kinetoplast DNA (kDNA) network constitute a particularly useful molecular tool because they are a multicopy target and present a variable region that differs among minicircle classes in the same network. Using the polymerase chain reaction (PCR) and a set of primers directed outwardly from the minicircle conserved region, it is possible to prepare molecular probes representing the pool of variable regions from the different minicircle classes in the kDNA. In order to examine the specificity of the minicircle variable region as hybridization probes in Leishmania (Viannia) species, such fragments were amplified from reference strains and from a panel of isolates representing the zymodeme diversity of Leishmania (Viannia) in Colombia. The size of the amplified products was conserved in Leishmania (Viannia) braziliensis, Leishmania (Viannia) guyanensis, and Leishmania (Viannia) panamensis (650 bp) and diverged in Leishmania (Viannia) equatorensis and Leishmania (Viannia) colombiensis (850 bp). The amplified products were further hybridized to variable region pools of Leishmania braziliensis, Leishmania panamensis, Leishmania guyanensis, and Leishmania equatorensis reference strains. The results obtained from the hybridization experiments support this approach as a means of defining relationships among strains. Hybridization allowed homologies to be perceived, whereas restriction fragment length analysis of the amplified products yielded strain-specific profiles. Apparently, L. (V.) equatorensis and L. (V.) colombiensis minicircle variable regions have no or only low homology with those of other Leishmania (Viannia) species, showing the divergence of those species within the subgenus.

Animals↗
PubMed1999

Polymerase chain reaction (PCR) as a laboratory tool for the evaluation of the parasitological cure in Chagas disease after specific treatment.

The evaluation of the treatment for chronic Chagas disease faces the absence of any clear-cut criterion of cure. The low degree of parasitemia and the persistence of positive immunologic reactions represent some of the difficulties involved in addressing therapeutic efficacy. Our aim was to define whether PCR could be used as a laboratory method for evaluating cure in Chagas disease after specific treatment. We tested the utility of PCR amplification of the variable regions of minicircles from Trypanosoma cruzi kinetoplast DNA, in 76 xeno-positive chronic Brazilian patients who have been treated with benznidazole in Mambai (Goias State) and São Felipe (Bahia State). We observed a positive amplification result in only 25 out of 76 treated patients (33%). Therefore, the performance of one single PCR after therapy revealed parasite clearance in 67% of the treated individuals, while xenodiagnosis was negative in 84%. These observations suggest that PCR is the most sensitive technique available for direct detection of T. cruzi in chagasic patients and that it can be a very useful instrument for the follow-up of patients after specific chemotherapy. In this sense, we are now developing a quantitative approach based on the use of fluorogenic probes and real-time measurement of the amplification reaction (TaqMan technology) in order to precisely estimate the parasite load in chronic chagasic patients before and after treatment. This may be the basis for the future establishment of reliable criteria of cure for patients undergoing therapy.

Chagas Disease↗
PubMed1998

Molecular epidemiology of American trypanosomiasis in Brazil based on dimorphisms of rRNA and mini-exon gene sequences.

American trypanosomiasis is transmitted in nature via a sylvatic cycle, where Trypanosoma cruzi interacts with wild triatomines and mammalian reservoirs, or via a domestic cycle where the parasite comes into contact with humans through domiciliated triatomines. The pool of T. cruzi isolates consists of sub-populations presenting a broad genetic diversity. In contrast to the heterogeneity suggested by isoenzyme analysis, PCR amplification of sequences from the 24S alpha rRNA gene and from the non-transcribed spacer of the mini-exon gene indicated dimorphism among T. cruzi isolates, which enabled the definition of two major parasite lineages. In the present study, 157 T. cruzi isolates obtained from humans, triatomines and sylvatic mammalian reservoirs from 12 Brazilian states were analysed by the 24S alpha RNA and mini-exon typing approaches. The stocks were classified into the two proposed lineages and according to the domestic or sylvatic cycle of the parasite. Data presented provide evidence for a strong association of T. cruzi lineage 1 with the domestic cycle, while in the sylvatic cycle both lineages circulate equally. Molecular typing of human parasite isolates from three well-characterised endemic regions of Chagas disease (Minas Gerais, Paraiba and Piaui) and from Amazonas State, where T. cruzi is enzootic, suggests that in some endemic areas in Brazil there is a preferential linkage between both cycles mediated by lineage-1 stocks.

Animals↗
PubMed1998

Leishmaniasis recidiva cutis in New World cutaneous leishmaniasis.

BACKGROUND: Leishmaniasis recidiva cutis (LRC) is rare in New World leishmaniasis. Only seven cases have been reported so far. MATERIALS AND METHODS: Four cases are reported here. Parasite diagnosis was performed by classical methods of touch preparations, histopathologic sections, and cultures. In addition, the detection of parasite DNA by the polymerase chain reaction (PCR) was performed in all cases. RESULTS: Parasites were detected by at least one of the classical methods in all primary lesions; however, only the PCR was positive in the recidivant lesions. DISCUSSION: LRC cases most likely represent a reactivation of an initial infection, probably due to the persistence of parasites in scarred tissue. Although lupoid leishmaniasis (LL) has been used as a synonym of LRC, a clear difference between LRC and LL can be defined as LL is the initial clinical presentation while LRC is a recurrent lesion. CONCLUSIONS: The results indicate that it is not appropriate to use these two denominations as synonyms. The designation of LRC should be maintained in order to define recidives occurring at the border of an old scar of cutaneous leishmaniasis, avoiding the confusion with the lupoid form of the disease.

Adult↗
PubMed1998

Detection of Leishmania DNA by polymerase chain reaction in scars of treated human patients.

Leishmaniasis is an endemic disease in developing countries. The efficacy of therapy is usually evaluated through clinical parameters. To define the parasitologic cure, 20 patients were biopsied before and 1 month to 8 years after treatment. Paraffin-embedded tissue was used for DNA isolation. All patients had a positive polymerase chain reaction (PCR) result before therapy, except 1, for whom no histopathologic material was available. The causative agent was identified as belonging to the Leishmania (Viannia) subgenus by hybridization. Despite clinical healing and absence of reactivation or development of mucosal lesions, PCR was positive in scars of 16 patients (80%). The results suggest that parasites persist in the skin for many years despite treatment. Depending on specific pathogenetic features of the parasite and the immune status of the host, this phenomenon might result in mucosal lesions. Alternatively, it could have a role in the maintenance of immunologic memory in patients living in areas in which leishmaniasis is endemic.

Animals↗
PubMed1998

Brazilian isolates of Trypanosoma cruzi from humans and triatomines classified into two lineages using mini-exon and ribosomal RNA sequences.

Traditional molecular and biochemical methods, such as schizodeme analysis, karyotyping, DNA fingerprinting, and enzyme electrophoretic profiles, have shown a large variability among Trypanosoma cruzi isolates. In contrast to those results, polymerase chain reaction (PCR) amplification of sequences from the 24S alpha ribosomal RNA gene and from the mini-exon gene nontranscribed spacer indicated a dimorphism among T. cruzi isolates, which enabled the definition of two major parasite lineages. In the present study, 86 T. cruzi field stocks (68 isolated from humans with defined presentations of Chagas' disease and 18 from triatomines) derived from four Brazilian geographic areas were typed by the PCR assay based on the DNA sequences of the mini-exon and 24S alpha rRNA genes. These stocks were ordered into the two major T. cruzi lineages. Lineage 1 was associated mainly with human isolates and lineage 2 with the sylvatic cycle of the parasite.

Animals↗