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S Oliveira

Publications and source records attributed to S Oliveira.

At least 37 records · Page 2Linked to original sources
PubMed2000

Molecular cloning of the gene encoding flavoredoxin, a flavoprotein from Desulfovibrio gigas.

Sulfate-reducing bacteria are rich in unique redox proteins and electron carriers that participate in a variety of essential pathways. Several studies have been carried out to characterize these proteins, but the structure and function of many are poorly understood. Many Desulfovibrio species can grow using hydrogen as the sole energy source, indicating that the oxidation of hydrogen with sulfite as the terminal electron acceptor is an energy-conserving mechanism. Flavoredoxin is an FMN-binding protein isolated from the sulfate-reducing bacteria Desulfovibrio gigas that participates in the reduction of bisulfite from hydrogen. Here we report the cloning and sequencing of the flavoredoxin gene. The derived amino acid sequence exhibits similarity to several flavoproteins which are members of a new family of flavin reductases suggested to bind FMN in a novel mode.

Amino Acid Sequence↗
PubMed2000

Structure of a dioxygen reduction enzyme from Desulfovibrio gigas.

Desulfovibrio gigas is a strict anaerobe that contains a well-characterized metabolic pathway that enables it to survive transient contacts with oxygen. The terminal enzyme in this pathway, rubredoxin:oxygen oxidoreductase (ROO) reduces oxygen to water in a direct and safe way. The 2.5 A resolution crystal structure of ROO shows that each monomer of this homodimeric enzyme consists of a novel combination of two domains, a flavodoxin-like domain and a Zn-beta-lactamase-like domain that contains a di-iron center for dioxygen reduction. This is the first structure of a member of a superfamily of enzymes widespread in strict and facultative anaerobes, indicating its broad physiological significance.

Amino Acid Sequence↗
PubMed2000

A DNA fragment of Desulfovibrio gigas genome containing replication origin related genes.

The nucleotide sequence of a 10,772 base pair (bp) region from Desulfovibrio gigas genome was determined. This sequence, which is adjacent to the region containing the coding units for the metalloproteins rubredoxin-oxygen oxidoreductase (ROO) and rubredoxin, includes the flavodoxin gene. Additionally, it also contains four open reading frames (ORFs) related to genes frequently found in replication origin regions of prokaryotes. These hypothetical encoded polypeptides are: the response regulator proteins (PhoP and PhoR) from the phosphate regulon, a DNA partitioning protein and an asparagine synthetase.

Amino Acid Sequence↗
PubMed1999

Desulfovibrio gigas neelaredoxin. A novel superoxide dismutase integrated in a putative oxygen sensory operon of an anaerobe.

Neelaredoxin, a small non-heme blue iron protein from the sulfate-reducing bacterium Desulfovibrio gigas [Chen, L., Sharma, P., LeGall, J., Mariano, A.M., Teixeira M. and Xavier, A.V. (1994) Eur. J. Biochem. 226, 613-618] is shown to be encoded by a polycistronic unit which contains two additional open reading frames (ORF-1 and ORF-2) coding for chemotaxis-like proteins. ORF-1 has domains highly homologous with those structurally and functionally important in methyl-accepting chemotaxis proteins, including two putative transmembrane helices, potential methylation sites and the interaction domain with CheW proteins. Interestingly, ORF-2 encodes a protein having homologies with CheW proteins. Neelaredoxin is also shown to have significant superoxide dismutase activity (1200 U. mg-1), making it a novel type of iron superoxide dismutase. Analysis of genomic data shows that neelaredoxin-like putative polypeptides are present in strict anaerobic archaea, suggesting that this is a primordial superoxide dismutase. The three proteins encoded in this operon may be involved in the oxygen-sensing mechanisms of this anaerobic bacterium, indicating a possible transcriptional mechanism to sense and respond to potential stress agents.

Amino Acid Sequence↗
PubMed1997

Studies on the redox centers of the terminal oxidase from Desulfovibrio gigas and evidence for its interaction with rubredoxin.

Rubredoxin-oxygen oxidoreductase (ROO) is the final component of a soluble electron transfer chain that couples NADH oxidation to oxygen consumption in the anaerobic sulfate reducer Desulfovibrio gigas. It is an 86-kDa homodimeric flavohemeprotein containing two FAD molecules, one mesoheme IX, and one Fe-uroporphyrin I per monomer, capable of fully reducing oxygen to water. EPR studies on the native enzyme reveal two components with g values at approximately 2.46, 2.29, and 1.89, which are assigned to low spin hemes and are similar to the EPR features of P-450 hemes, suggesting that ROO hemes have a cysteinyl axial ligation. At pH 7.6, the flavin redox transitions occur at 0 +/- 15 mV for the quinone/semiquinone couple and at -130 +/- 15 mV for the semiquinone/hydroquinone couple; the hemes reduction potential is -350 +/- 15 mV. Spectroscopic studies provided unequivocal evidence that the flavins are the electron acceptor centers from rubredoxin, and that their reduction proceed through an anionic semiquinone radical. The reaction with oxygen occurs in the flavin moiety. These data are strongly corroborated by the finding that rubredoxin and ROO are located in the same polycistronic unit of D. gigas genome. For the first time, a clear role for a rubredoxin in a sulfate-reducing bacterium is presented.

Amino Acid Sequence↗
PubMed1997

[Quality of quality: a workers' health perspective]

In Brazil, new forms of labor organization based on the so-called Japanese management model are characterized by the implementation of Total Quality Programs, heavily altering relations in the labor force. Pressures brought to bear by modernity, such as demand for quality, affect workers and result in physical and mental disturbances. A case study focusing on a textile industry in Nova Friburgo, Rio de Janeiro State, aimed at elucidating how such programs are formulated in such a way as to increase product quality without changing quality of life for workers. We detected precarious work conditions alongside sophisticated requirements, including abstraction, internalized control, dissemination of the supplier/client concept, etc., running up against a labor force with limited schooling, thus creating a tense atmosphere with a steady speed-up in the work pace, albeit with no real gains for workers.

Journal Article↗
PubMed1996

T lymphocyte mediated protection against facultative intracellular bacteria.

Acquired immunity against intracellular bacteria is T cell dependent. T cells play a major role in protection against intracellular bacteria, but bacterial antigens recognized by T cells have been studied less extensively than bacterial antigens recognized by B cells. Using T lymphocytes from animals immunized against Brucella abortus, we have screened a bacterial genomic library for genes encoding antigens recognized by T cells. Lymphocytes that proliferated to B. abortus proteins were characterized for phenotype and cytokine activity. Bovine and murine lymphocytes recognized common bacterial antigens and possessed similar cytokine profiles, suggesting an analogous immune response in these two animal species. In vivo protection afforded by a particular cell type is dependent on the bacterial antigens presented and mechanisms of antigen presentation. MHC class I and class II gene knockout animals infected with B. abortus have demonstrated that protection to B. abortus is especially dependent on CD8+ T cells. Knowing the cells required for protection, vaccines can be designed to elicit the protective subset of lymphocytes. Currently, we are testing several recombinant B. abortus proteins using different immunization strategies. Finally, bacterial genes activated following intracellular phagocytosis are being examined using a novel, reporter system adapted to B. abortus.

Animals↗
PubMed1995

Replication of transfected plasmid DNA by cells infected with African swine fever virus.

Recombinant plasmids containing African swine fever virus (ASFV) DNA fragments covering all the virus genome were transfected into infected cells in order to detect viral origins of DNA replication. Plasmid replication was monitored by sensitivity to MboI, which cleaves only replicated, unmethylated DNA, and resistance to DpnI, which cleaves only the same methylated sequence. All the recombinants replicated to a similar extent, indicating that ASFV does not use a preferred origin for DNA replication. Circular plasmids without viral inserts were also replicated, but linearized plasmids or lambda bacteriophage DNA were not replicated. Replicated plasmid DNA began to accumulate with a time course similar to viral DNA, starting between 6 and 12 hr p.i. and increasing steadily for about 18 hr. This apparent dependence on viral functions was confirmed by the sensitivity of plasmid replication to phosphonoacetic acid and resistance to aphidicolin and by the reduction of replication in cells infected with a mutant defective in DNA replication. Replicated plasmid DNA present as unit length circles and as large dimension forms, probably head-to-tail concatemers. The results of two-dimensional electrophoresis (neutral/alkaline) favor a rolling-circle mechanism for plasmid DNA replication.

African Swine Fever Virus↗
PubMed1991

Wide distribution of the variant form of the human malaria parasite Plasmodium vivax.

We have found polymorphism in the repetitive and nonrepetitive regions of the sporozoite vaccine antigen, the circumsporozoite (CS) protein, in Plasmodium vivax malaria parasites from two geographically distant malaria endemic regions of the world. Like the recently described variant repeat sequence of P. vivax from Thailand, the CS protein repeat sequence of the variant P. vivax parasites from Papua New Guinea and Brazil is ANGA(G/D)(N/D)QPG, which differs from the previously identified CS repeat sequence, GDRA(D/A)GQPA, of P. vivax parasites from South America, Central America, and North Korea. Comparison of the P. vivax CS protein outside the repeat region revealed restricted polymorphism in regions that have exhibited T-cell immune function and sequence heterogeneity in the CS protein of Plasmodium falciparum. Our results show that P. vivax malaria parasites with the variant CS repeat sequences are widespread in nature and that the polymorphism in the CS protein of P. vivax is also present in the nonrepeat region.

Amino Acid Sequence↗
PubMed1991

Clinical experience of emergency coronary artery bypass grafting following failed percutaneous transluminal coronary angioplasty.

From July, 1981 to December, 1988, 2431 percutaneous transluminal coronary angioplasties were performed on 1901 patients at the Heart Institute of São Paulo University Medical School. Seventy-six patients (4.0 per cent) underwent emergency coronary artery bypass grafting for failed angioplasty. The incidence of failed angioplasty was significantly higher in the impending myocardial infarction group (11.5 per cent) than in the angina group (4.8 per cent) and the acute myocardial infarction group (1.3 per cent). The mean age of the seventy-six patients was 54.4 years, and 54 patients were male. The operative mortality was 15.8 per cent, being 9 males and 3 females. Patients who had had a left main trunk dissection during angioplasty and those who were hemodynamically unstable following the failed angioplasty or who had had a cardiac arrest necessitating a cardiac massage during transportation to the operating room, had a higher mortality than patients in whom the failure occurred in other sites and those who were hemodynamically stable. Perioperative myocardial infarction was documented in 50 per cent of the patients. Patients who had had a cardiac arrest during the procedure had a higher rate of perioperative myocardial infarction than those whose preoperative hemodynamic condition was stable.

Angina Pectoris↗
PubMed1990

Genetic diversity of Plasmodium falciparum shows geographical variation.

Sixty Plasmodium falciparum isolates, 20 each from Thailand, Zimbabwe, and Brazil, were characterized for 20 variant genetic markers, including the enzymes glucose phosphate isomerase, adenosine deaminase and peptidase, 11 other proteins detected by 2-dimensional electrophoresis (2D-PAGE), 2 merozoite surface antigens (MSA-1 and MSA-2), one exported antigen (Exp-1), and sensitivity to the drugs chloroquine, pyrimethamine, and mefloquine. The study examines the extent of diversity between individual isolates and the differences in the frequency of certain variants of the markers between the 3 countries. The principal conclusions to be drawn from the study are that there is extensive polymorphism in many of the genetically determined characters of this parasite, multiple infections with greater than 1 genetically distinct parasite are common, and there are geographical variations in the frequencies with which variant forms of certain markers occur.

Alleles↗
PubMedDate not supplied

Use of glass beads and CF 11 cellulose for removal of leukocytes from malaria-infected human blood in field settings.

Passage of malaria-infected blood through a two-layered column composed of acid-washed glass beads and CF 11 cellulose removes white cells from parasitized blood. However, because use of glass beads and CF 11 cellulose requires filtration of infected blood separately through these two resins and the addition of ADP, the procedure is time-consuming and may be inappropriate for use in the field, especially when large numbers of blood samples are to be treated. Our modification of this process yields parasitized cells free of contaminating leukocytes, and because of its operational simplicity, large numbers of blood samples can be processed. Our procedure also compares well with those using expensive commercial Sepacell resins in its ability to separate leukocytes from whole blood. As a test of usefulness in molecular biologic investigations, the parasites obtained from the blood of malaria-infected patients using the modified procedure yield genomic DNA whose single copy gene, the circumsporozoite gene, efficiently amplifies by polymerase chain reaction.

Adenosine Diphosphate↗
PubMedDate not supplied

[Favism].

Favism is an acute hemolytic syndrome occurring in glucose-6-phosphate dehydrogenase (G6PD) deficient individuals after the consumption of fava beans. The authors report the clinical case of a 16 year-old boy admitted to hospital with an acute hemolytic episode after the ingestion of fava beans. Complementary studies revealed G6PD deficiency. A study of the family and a short review about favism is presented.

Abdominal Pain↗
PubMedDate not supplied

[A case of epilepsy simulating a pheochromocytoma].

INTRODUCTION: Autonomic epilepsy is a rare entity that results from an epileptogenic focus involving certain structures belonging to the autonomous nervous system; it is characterised by the occurrence of convulsive seizures that consist in autonomic phenomena. CASE REPORT: We report the case of a 28-year-old female patient who suffered paroxysmal episodes similar to those accompanying a pheochromocytoma. Following a thorough examination, both the presence of a tumour and the anomalous production of catecholamines were excluded and, although it was not possible to provide electroencephalographic evidence, the patient was diagnosed as suffering from autonomous epilepsy, which was later confirmed by the clinical efficacy of valproic acid therapy. CONCLUSIONS: Autonomic seizures often show characteristics that are singular or similar to those of other clinical entities. This makes the disorder difficult to diagnose and sometimes requires therapeutic testing with anticonvulsive drugs.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Cyclosporine A in juvenile idiopathic arthritis. Results of the PRCSG/PRINTO phase IV post marketing surveillance study.

OBJECTIVE: To investigate the clinical use patterns, clinical effect and safety of cyclosporine A (CSA) in juvenile idiopathic arthritis (JIA) in the setting of routine clinical care. METHODS: An open-ended, phase IV post marketing surveillance study was conducted among members of the Pediatric Rheumatology Collaborative Study Group (PRCSG) and of the Paediatric Rheumatology International Trials Organisation (PRINTO) to identify patients with polyarticular course JIA who had received CSA during the course of their disease. RESULTS: A total of 329 patients, half of whom had systemic JIA, were collected in 21 countries. Data were collected during 1240 routine clinic visits. CSA was started at a mean of 5.8 years after disease onset and was given at a mean dose of 3.4 mg/kg/day. The drug was administered in combination with MTX in 61% and along with prednisone in 65% of the patients who were still receiving CSA. Among patients who were still receiving CSA therapy at the last reported visit, remission was documented in 9% of the patients, whereas in 61% of the patients the disease activity was rated as moderate or severe. The most frequent reason for discontinuation of CSA was insufficient therapeutic effect (61% of the patients); only 10% of the patients stopped CSA because of remission. In 17% of the patients, side effects of therapy was given as the primary reason for discontinuation. CONCLUSION: This survey suggests that CSA may have a less favourable efficacy profile than MTX and etanercept, whereas the frequency of side effects may be similar. The exact place of CSA in the treatment of JIA can only be established via controlled clinical trial.

Antirheumatic Agents↗