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M R Carvalho

Publications and source records attributed to M R Carvalho.

17 recordsLinked to original sources
PubMed2000

PPB1, a putative spliced leader RNA gene transcription factor in Trypanosoma cruzi.

In trypanosomatids, the spliced leader RNA, or SL RNA, donates its 5' 39 nucleotides to mature nuclear mRNAs in a process termed trans-splicing. We have previously characterized the SL RNA gene from Trypanosoma cruzi and identified its transcription promoter, including a 14 nt proximal sequence element, or PSE, that binds a putative transcription factor and activates transcription of the gene. Herein, we describe establishment of a yeast one-hybrid system using the 14 nt PSE as bait, and use this system to select T. cruzi cDNAs encoding a putative transcription factor that activates transcription of the SL RNA gene. The cDNA was selected from a normalized library and encodes an approximately 45 kDa putative PSE promoter-binding protein, PPB1. PPB1 in vitro translated or overexpressed in and isolated from transformed E. coli, showed PSE-specific binding activity by electrophoretic mobility shift assays. Finally, overexpression of PPB1 in T. cruzi led to increased expression of the SL RNA gene as well as reporter genes in episomal constructs under the control of the SL RNA gene promoter. These observations suggest that PPB1 is a transcription factor that plays an important role in SL RNA gene expression.

Amino Acid Sequence↗
PubMed1998

Relative importance of phytohemagglutinin (lectin) and trypsin-chymotrypsin inhibitor on bean (Phaseolus vulgaris L) protein absorption and utilization by the rat.

The main objective of this work was to perform a comparative study of the antinutritional and/or toxic properties of phytohemagglutinin and trypsin-chymotrypsin inhibitor extracted from the seed of a commercial cultivar of edible bean used in Brazil. Bean proteins were extracted in acidic salt solution and fractionated by dialysis and centrifugation, then freeze-dried. The total freeze-dried bean extract and the globulin or albumin protein fraction were resuspended in distilled water and heated (100 degrees C, 30 min) for inactivation of hemagglutinin. Diets were prepared with unheated bean protein fractions and heated ones (100% trypsin inhibitor activity, but 0% phytohemagglutinin activity). As a result, the inhibition of growth and poor dietary protein utilization were observed in rats fed diets containing unheated bean protein fractions, but not in rats fed diets containing heated fractions. It was thus assumed that phytohemagglutinin is the main antinutritional and toxic factor that in dry bean (Phaseolus) protein and that trypsin inhibitor (Bowman-Birk type) did not interfere with rat growth.

Absorption↗
PubMed1997

The transcription promoter of the spliced leader gene from Trypanosoma cruzi.

A putative promoter element responsible for transcription of the spliced leader (SL) gene of Trypanosoma cruzi was identified by overlapping deletion and linker scanning analyses of the upstream flanking sequences using the bacterial chloramphenicol acetyltransferase (CAT) gene as a reporter in transient transfections of cultured epimastigotes. Deletion or substitution of a proximal sequence element (PSE) between positions -53 and -40 relative to the transcription start point eliminated CAT gene expression. Comparison of SL genes from several strains of T. cruzi revealed two alternative sequence patterns for the putative SL PSE, both composed of a short run of purines followed by a run of pyrimidines. Moreover, an examination of these sequences supports the subdivision of T. cruzi isolates into two divergent groups. Double-stranded oligonucleotides containing the sequence of the PSE exhibited specific gel mobility shifts after incubation with T. cruzi nuclear extracts, suggesting that a transcription factor binds this site. Finally, experiments designed to increase the level of CAT expression from the SL promoter suggest that it is not a strong promoter in cultured T. cruzi epimastigotes.

Animals↗
PubMed1996

A gene (RPGR) with homology to the RCC1 guanine nucleotide exchange factor is mutated in X-linked retinitis pigmentosa (RP3).

X-linked retinitis pigmentosa (xlRP) is a severe progressive retinal degeneration which affects about 1 in 25,000 of the population. The most common form of xlRP, RP3, has been localised to the interval between CYBB and OTC in Xp21.1 by linkage analysis and deletion mapping. Identification of microdeletions within this region has now led to the positional cloning of a gene, RPGR, that spans 60 kg of genomic DNA and is ubiquitously expressed. The predicted 90 kD protein contains in its N-terminal half a tandem repeat structure highly similar to RCC1 (regulator of chromosome condensation), suggesting an interaction with a small GTPase. The C-terminal half contains a domain, rich in acidic residues, and ends in a potential isoprenylation anchorage site. The two intragenic deletions, two nonsense and three missense mutations within conserved domains provide evidence that RPGR (retinitis pigmentosa GTPase regulator) is the RP3 gene.

Amino Acid Sequence↗
PubMed1995

A gene (SRPX) encoding a sushi-repeat-containing protein is deleted in patients with X-linked retinitis pigmentosa.

X-linked retinitis pigmentosa (XLRP) is characterized by retinal degeneration with night blindness and progressive reduction of the visual fields. By linkage and deletion analysis a gene locus (RP3) has been mapped to the short arm of the X chromosome between the genes CYBB and OTC. Analysis of transcript in this region has revealed a gene which is abundantly expressed in human retina and encodes a putative membrane protein with significant homologies to short consensus repeat (SCR/sushi) domains known from selections and complement proteins. The gene termed SRPX (sushi-repeat-containing protein, x chromosome) is deleted in an RP patient who also suffers from chronic granulomatous disease and McLeod syndrome. A 75 kb deletion removing exon 1 of the gene was also found in two brothers of a second XLRP family. However, no further functionally significant mutations were detected by SSCP screening of all 10 exons in 34 unrelated XLRP patients nor by full length RT-PCR sequencing in two RP3 families. The role of this highly conserved retinal gene in the pathogenesis of RP therefore remains to be determined.

Adult↗
PubMed1993

Chagas' disease diagnosis: evaluation of several tests in blood bank screening.

Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease.

Antigens, Protozoan↗
PubMed1993

A study of the importance of the enterotoxigenic E. coli in children with acute diarrhoea in Recife, Brazil.

Even today acute diarrhoea is a major cause of morbidity and mortality in young children. It is a serious public health problem in less-developed countries, primarily in households whose income is low. As such, it is one of the main causes of death, affecting the undernourished in particular. The potential enteropathogenic agents are distributed universally. However, there is a major difference in the prevalence, according to the areas and the characteristics of the population groups which were studied. In Brazil, since the 1970s, our attention has been drawn to the importance of the classic enteropathogenic strains of E. coli (EPEC) in the aetiology of diarrhoeal diseases, primarily those present in weaned infants in inner city neighbourhoods. On the other hand, Guerrant and co-workers, and Queiroz and co-workers found significant percentages of isolated colonies of enterotoxigenic coli (ETEC) in the stool material of children with symptoms of acute diarrhoea. In rural areas of less-developed countries the incidence of episodes of ETEC provoking diarrhoea is estimated to be between five and ten per person/year. Due to the social and medical gravity of acute diarrhoea, and to the lack of studies dealing with the aetiopathogenic role of the strains of ETEC in our area, we decided to analyse the frequency of isolation of ETEC in children with and without diarrhoea who were attending the out-patient department of the Instituto Materno Infantil de Pernambuco/IMIP.

Acute Disease↗
PubMed1992

Leber's hereditary optic neuroretinopathy and the X-chromosomal susceptibility factor: no linkage to DXs7.

Leber's hereditary optic neuroretinopathy (LHON) was the first human disease for which mitochondrial inheritance was demonstrated. Analysis of genealogies, however, suggests the existence of an interacting X-linked factor, and linkage to DXS7 was recently described. We tested this location in four LHON families, with DXS7 and two flanking markers, OTC and DXS426. We found recombinations with DXS7 in two families and with DXS426 in one. The two point lod scores to DXS7 were negative with all the allele frequencies for the X-linked factor tested (q = 0.5; 0.35; 0.05).

Female↗
PubMed1992

Use of recombinant antigens for the accurate immunodiagnosis of Chagas' disease.

We tested two Trypanosoma cruzi recombinant antigens in a diagnostic test for Chagas' disease. These antigens were a cytoplasmic repetitive antigen (CRA) and a flagellar repetitive antigen (FRA). The results indicate that the recombinant antigens give better results when used in combination than when used separately, and that the removal of the beta-galactosidase portion of the recombinant fusion proteins increases the specificity of the diagnostic test for Chagas' disease. In addition, a direct enzyme-linked immunosorbent assay (ELISA), which involves the use of peroxidase-labeled antigens to detect the immune-complexes, was developed and compared with a conventional ELISA. The results indicate that the recombinant (CRA+FRA) ELISA is better than the conventional ELISA in the diagnosis of Chagas' disease, providing 100% specificity and sensitivity in all sera tested to date. The recombinant ELISA was compared with conventional serologic tests (hemagglutination and immunofluorescence) for Chagas' disease diagnosis, and the results show that the recombinant ELISA does not give rise to false-positive results that are observed with the two other tests. The use of the recombinant ELISA should be useful in the prevention of transmission of Chagas' disease by blood transfusions.

Animals↗
PubMed1991

[Post-vaccination tuberculin response using PPD derived from BCG].

The aim of this study was to compare the biological response obtained with two tuberculin tests--PPD-RT 23 and PPD derived from BCG--among children already vaccinated with the Calmette-Guérin bacillus. Results varied widely, and the differences observed were statistically significant. This shows the need for additional studies to assess the sensitivity, specificity and predictive value of both tests.

BCG Vaccine↗
PubMed1989

A double-blind clinical trial with a lotion containing 5% benzoyl peroxide and 2% miconazole in patients with acne vulgaris.

The therapeutic efficacy of a lotion containing 5% benzoyl peroxide and 2% miconazole was compared with 5% benzoyl peroxide alone, in a double-blind, randomized, parallel study. Thirty patients with comedonal or inflammatory acne vulgaris were enrolled. The medications were applied once daily during the first week, and then twice daily for the rest of the trial (45 days). In patients with comedonal acne there was no difference in the effect of the two therapies. In patients with inflammatory acne the percentage reduction of the number of lesions on Day 30 was significantly higher in the benzoyl peroxide plus miconazole group (66%) compared to benzoyl peroxide alone (37%). At Day 45 there was a trend favouring the combined therapy but the difference was not significant. There were no significant differences in the adverse reactions reported by the two groups of patients (erythema, itching or moderate exfoliation).

Acne Vulgaris↗
PubMed1989

[Endomyocardial fibrosis: surgical treatment].

The authors analyse the experience acquired for surgical treatment of endomyocardiofibrosis. Among the 15 patients submitted to the operation, nine had the biventricular form, four had the disease in the right ventricle and two only in the left ventricle. The surgery consisted of endocardioectomy of the ventricles (RV--04,LV--02, bilateral--08) and replacement of the diseased atrioventricular valves (mitral--02, tricuspid--06, mitral and tricuspid--07). In one patient there was severe obstruction of the anterior descending artery and a bypass was done. Three patients had associated rheumatic mitral stenosis. There was one early operative death and three late deaths (respectively 13.34 and 37 months later). Two patients required re-operation. The first one, 33 months later, to replace the mitral valve which had been preserved in the first procedure, and the second, 12 months later, who presented ventricular septal defect secondary to rupture of the weak septum. Of all the patients who underwent surgery, 11 survived and all, except one, have had a good course. The detailed analysis of this series permitted us to conclude that: 1st--the general use of the bidimensional echocardiography in high risk patients, allows early diagnosis in a greater number of them; 2nd, the surgery must be early to avoid cardiac and extracardiac injury due to the disease; 3rd--a low profile valve must be used; 4th--to this moment there have been no signs of recurrence; 5th--surgical treatment appears to improve the course of this terrible disease.

Adolescent↗
PubMed1985

Coarctation of the aorta: a new surgical technique.

We developed a new surgical technique to treat coarctation of the aorta. It consists of an aortoplasty in which the left subclavian artery is transected, opened longitudinally, and sutured to the coarctated segment so as to correct the narrowing and also maintain blood flow through the left upper limb.

Aortic Coarctation↗