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Biomedical subjects

O Martins

Publications and source records attributed to O Martins.

At least 19 recordsLinked to original sources
PubMed1997

Glu-tRNAGln amidotransferase: a novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation.

The three genes, gatC, gatA, and gatB, which constitute the transcriptional unit of the Bacillus subtilis glutamyl-tRNAGln amidotransferase have been cloned. Expression of this transcriptional unit results in the production of a heterotrimeric protein that has been purified to homogeneity. The enzyme furnishes a means for formation of correctly charged Gln-tRNAGln through the transamidation of misacylated Glu-tRNAGln, functionally replacing the lack of glutaminyl-tRNA synthetase activity in Gram-positive eubacteria, cyanobacteria, Archaea, and organelles. Disruption of this operon is lethal. This demonstrates that transamidation is the only pathway to Gln-tRNAGln in B. subtilis and that glutamyl-tRNAGln amidotransferase is a novel and essential component of the translational apparatus.

Acylation↗
PubMed1997

The effect of LPS on cytokine synthesis and lung neutrophil influx after hepatic ischemia/reperfusion injury in the rat.

OBJECTIVE: To determine if cytokine responses and lung injury induced by intravenous (i.v.) lipopolysaccharide (LPS) at 4 hr were enhanced in rats that had been previously subjected to 30 min of total liver ischemia (Pringle's maneuver) followed by 24 hr or 3 days of reperfusion. BACKGROUND: Many patients with liver trauma require occlusion of hepatic blood flow to control hemorrhage and facilitate repair. A significant number of these patients subsequently develop the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD) characterized by the release of cytokines and tissue neutrophil influx. Macrophages, including Kupffer cells, may be activated by ischemic injury and dysregulation of their response to LPS may contribute to the development of SIRS and acute respiratory distress syndrome. METHODS: Adult male Sprague-Dawley rats were randomly divided into six groups: three groups received total hepatic ischemia for 30 min and three groups had a sham procedure. Twenty-four hours or 3 days after hepatic ischemia/reperfusion injury, rats were treated with LPS (5 mg/kg) or saline and monitored for 4 hr. We collected serum, bronchoalveolar lavage (BAL) fluid, and lung tissue. RESULTS: Serum and BAL cytokine concentrations were significantly increased by i.v. LPS; however, hepatic ischemia/reperfusion injury 24 hr or 3 days before iv LPS ameliorated this cytokine response. The LPS-induced pulmonary neutrophil influx and histopathological changes were similar in sham and hepatic ischemia/reperfusion-injured groups. CONCLUSIONS: Hepatic ischemia/reperfusion injury significantly attenuated the serum and BAL cytokine concentrations, but did not change pulmonary neutrophil influx or histopathological alterations in response to i.v. LPS.

Animals↗
PubMed1997

Relative impact of HLA phenotype and CD4-CD8 ratios on the clinical expression of hemochromatosis.

Hemochromatosis is a hereditary iron-overload disease linked to HLA. The clinical expression of hemochromatosis is influenced by sex and age. However, other factors must account for the notorious heterogeneity of expression of the disease independent of sex, age, and HLA phenotype. The present study attempts to clarify some of these additional factors based on exhaustive statistical analysis of data collected from 43 selected patients with hemochromatosis. The statistical analysis focused on three groups of variables: the first group included variables reflecting the clinical expression of the disease; the second group represented the biochemical and hematological values at the time of diagnosis; and the third group consisted of the independent variables sex, age, HLA phenotype, and T-cell subset profile, i.e., the percentages and total numbers of CD4+ and CD8+ cells and the CD4-CD8 ratios. The results show that the relative expansion of the two main T-cell subsets, in the context of the HLA phenotype, correlates significantly with the clinical expression of hemochromatosis and the severity of iron overload. The present findings substantiate further the postulate that T cells have a role in the regulation of iron metabolism.

Adult↗
PubMed1997

A nuclear genetic lesion affecting Saccharomyces cerevisiae mitochondrial translation is complemented by a homologous Bacillus gene.

A novel Bacillus gene was isolated and characterized. It encodes a homolog of Saccharomyces cerevisiae Pet112p, a protein that has no characterized relative and is dispensable for cell viability but required for mitochondrial translation. Expression of the Bacillus protein in yeast, modified to ensure mitochondrial targeting, partially complemented the phenotype of the pet112-1 mutation, demonstrating a high degree of evolutionary conservation for this as yet unidentified component of translation.

Bacillus subtilis↗
PubMed1994

[The imaging diagnosis of craniocerebral trauma. The general concepts].

The author makes a concise review of the imagiology of acute head trauma. The relative value of the various imaging techniques and the present importance of skull radiography are discussed; the role of computed tomography (CT) is emphasized. The most important aspects of traumatic lesions, as evaluated by CT, are presented.

Acute Disease↗
PubMed1992

Brain Na+ K+ ATPase and cholesterol in acute experimental trypanosomiasis.

Brain Na+ K+ ATPase activity has been found to decrease in experimental trypanosomiasis in rats infected with Trypanosoma congolense. Some physical features that affect membrane fluidity were also observed to be altered. The levels of cholesterol in the brain and free fatty acids in the serum were found to increase in the infected animals. These findings might be relevant to the development of brain lesions.

Animals↗
PubMed1982

Surgical treatment of two squamous-cell carcinomas in the same lip: case report.

We report one patient who developed two squamous-cell carcinomas on different parts of the lower lip. The tumors were excised by the UV technique, a variation of the V-shped excision. We repaired the defect caused by excision of the first lesion by direct closure and that caused by extirpation of the second lesion by use of a transposition flap (Abbe-Estlander technique).

Carcinoma, Squamous Cell↗
PubMed1981

Possible mechanism of action of cholesterol enriched diet on the thyroid.

Groups of male Sprague Dawley rats aged 60 days were fed either a control diet (CD) or the same diet enriched with 1% cholesterol (CHD) for 30 days. In CHD fed animals an increase of 131I uptake by thyroid, PB131I and TSH level in plasma was found, while the level of thyroxine (T4) was unchanged and that of triiodothyronine (T3) was decreased. In the animals treated with T3 (20 micrograms i.p. daily) a decrease of 131I uptake by thyroid and of T4 and TSH level in plasma was found irrespectively of a cholesterol content in the diet. However, PB131I level was decreased in CHD fed and T3 treated animals compared to those fed CD under the same treatment. Finally, in the animals treated with cimetidine (10 mg i.p. daily) no changes of any measure was found after CD feeding as compared to untreated ones, while CHD in such animals resulted in a decreased of T3 level. The site of cholesterol action appears to be at the hypothalamus-pituitary system since TSH suppressed animals (i.e. T3 treated) did not show any thyroid stimulation when fed with a cholesterol excess. Furthermore, thyroidectomized animals showed increased TSH in plasma after cholesterol feeding. In the present study, chronic administration of cimetidine completely abolished thyroid gland stimulation promoted by cholesterol feeding thus suggesting that central histamine may play a considerable role in this process.

Animals↗