Biomedical subjects

T Fernandes

Publications and source records attributed to T Fernandes.

6 recordsLinked to original sources

PubMed1999

[Radiation therapy and cardiac pacemakers].

The number of patients with cardiac pacemakers submitted annually to radiation therapy is increasing. Radiation therapy causes interference in the normal functioning processes, directly by chemical changes in the structure of the device and also by electromagnetic disturbances generated in the process of treatment. The changes in the technology used in the manufacture of cardiac pacemakers after the 70's, with the introduction of complementary metal-oxide semi-conductors (CMOS) in the circuits, drastically increased the chance of dangerous interference in the normal function of cardiac pacemakers occurring when in contact with an ionizing radiation source. The authors briefly describe the mechanisms underlying the radio-induced damage usually observed. A review of the literature on this issue is made and solutions are pointed out to perform safe radiation therapy and minimize the risk of device malfunction.

Equipment Failure↗

PubMed1998

[The role of external radiotherapy in the treatment of medullary carcinoma of the thyroid].

Medullary carcinoma of the thyroid represents 3 to 10% of all thyroid cancers. Surgery is the main treatment. External beam radiotherapy has a fundamental role in the treatment of residual disease following surgery, in cases of cervical node involvement, and in unresectable tumors. Between 1975 and 1993, 12 patients with medullary carcinoma of the thyroid were treated at the Department of Radiotherapy of the Portuguese Institute of Oncology in Oporto. Nine of these patients (75%) were male and 3 (25%) female, ranging from 24 to 80 years of age (mean = 43). All of them had residual tumor after surgery and underwent treatment with external beam radiotherapy. The follow-up period ranged from 36 to 180 months, with a median of 78 months; 8 patients (66.7%) are alive, 5 of them show no evidence of disease. Average survival was 70 months, and 4 patients (33%) died with metastatic disease. The aim of this paper is to analyse the role of external beam radiotherapy in local control of these tumors, with a brief review of the literature.

Adult↗

PubMed1998

[Giant-cell tumor of bone].

Giant-cell bone tumors are a rare entity. Only 7.5 to 15% are malignant tumors and correspond to 0.5% of all primary malignant bone tumors. This case report has an unusual localization (ischium) for this kind of tumor (+/- 0.6%). The patient was treated with radiotherapy alone, because local extension of the disease would require very aggressive surgery with functional implications. Ten years after treatment, the patient is alive without clinical evidence of disease, and without functional impairments.

Bone Neoplasms↗

PubMed1998

[Gliosarcomas].

Gliosarcomas are rare tumors of the central nervous system with a poor prognosis. Histologically these tumors are characterized by an admixture of neoplastic glial cells and sarcomatous elements. Due to the scarcity of data in literature, the diagnosis is often missed and treatment is difficult. The authors report three cases of cerebral gliosarcomas and review the literature on this subject.

Adult↗

PubMed1995

Blood monocytes in rheumatoid arthritis are highly adherent to cultured endothelium.

Monocytes from 17 patients with rheumatoid arthritis (RA) were more adherent than monocytes from 17 control patients to monolayers of pig aortic endothelium irrespective of whether sera was included (median 27-34% increase; p = 0.002) or omitted (median 27% increase; p = 0.022) from the culture media. When human umbilical vein endothelial cells were used as the adherence substrate, rheumatoid monocytes from an additional 21 patients demonstrated a median 31% (p = 0.004) and 20% increase (p = 0.004) in adhesion when compared with monocytes from 21 normal healthy subjects in the absence and presence of autologous sera, respectively. Activation of control monocytes with muramyl dipeptide or treatment with RA sera increased their attachment to endothelium (mean 34 +/- 14% increase; p < 0.001). The expression of the adhesion molecules CD11b (p < 0.005), CD18 (p < 0.005), CD62L (p = 0.01) was enhanced on rheumatoid monocytes, but antibody-blocking studies suggested that CD18 and CD62L were not responsible for the augmented binding of the rheumatoid cells. A subpopulation of rheumatoid monocytes possessed a very low net negative surface charge, a property that favours binding to vessel walls. We propose that many rheumatoid monocytes are predisposed for sheer-resistant adhesion to vascular endothelium.

Adult↗

PubMed1994

A role for osmotic stress-induced proteins in the osmotolerance of a nitrogen-fixing cyanobacterium, Anabaena sp. strain L-31.

The molecular basis of tolerance to osmotic stress was investigated with a cyanobacterium, Anabaena sp. strain L-31. The inherent osmotolerance of this strain (50% growth inhibition at 350 mM sucrose) was enhanced by adaptation with 100 mM sucrose for 30 min. Addition of 10 mM KNO3 during growth also conferred significant osmoprotection, but addition of 3 mM NH4Cl did not. Exposure of cells to 350 mM sucrose induced the expression of at least 12 osmotic-stress-induced proteins (OSPs) within 30 min, in the molecular mass range of 11.5 to 84 kDa. Exposure of cells to 100 mM sucrose or to 10 mM nitrate also induced all the OSPs, but addition of ammonium did not. The observed correspondence between the presence of OSPs and osmotolerance strongly suggests a role for OSPs in osmotolerance of Anabaena sp. strain L-31.

Anabaena↗