Biomedical subjects

O Sousa

Publications and source records attributed to O Sousa.

8 recordsLinked to original sources

PubMed1999

Evaluation of recombinant antigens for serodiagnosis of Chagas' disease in South and Central America.

The commercially available diagnostic tests for Chagas' disease employ whole extracts or semipurified fractions of Trypanosoma cruzi epimastigotes. Considerable variation in the reproducibility and reliability of these tests has been reported by different research laboratories, mainly due to cross-reactivity with other pathogens and standardization of the reagents. The use of recombinant antigens for the serodiagnosis of Chagas' disease is recommended to increase the sensitivity and specificity of serological tests. Expressed in Escherichia coli, as fusion products with glutathione S-transferase, six T. cruzi recombinant antigens (H49, JL7, A13, B13, JL8, and 1F8) were evaluated in an enzyme-linked immunosorbent assay for Chagas' disease. The study was carried out with a panel of 541 serum samples of chagasic and nonchagasic patients from nine countries of Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Guatemala, Honduras, and Venezuela). The optimal concentration of each recombinant antigen for coating of plates was determined with the help of 125I-labelled recombinant proteins. While the specificity of the epimastigote antigen was 84% because of false positives from leishmaniasis cases, for the recombinant antigens it varied from 96.2 to 99.6%. Recombinant antigens reacted with 79 to 100% of serum samples from chronic chagasic patients. In this way, it is proposed that a mixture of a few T. cruzi recombinant antigens should be employed in a diagnostic kit to minimize individual variation and promote high sensitivity in the diagnosis of Chagas' disease.

Animals↗

PubMed1998

[Monoclonal antibodies. General approach and radioimmunotherapy].

Two major obstacles to systemic cancer therapy are the lack of specificity of therapeutic modalities and the intrapatient and interpatient heterogeneity of cancer cells. Because of their natural specificity, antibodies directed against tumor specific or tumor associated antigens have been raising interest in oncology. This article makes an overview of the basic principles of monoclonal antibodies, their limitations and perspectives, with particular attention to Immunoradioconjugates. The most important Immunoradiotherapy clinical studies are also reviewed.

Antibodies, Monoclonal↗

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

[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↗

PubMed1994

[Otorhinolaryngologic symptoms caused by the intranasal abuse of cocaine. Report of a case].

Cocaine abuse is associated with medical complications that depends on the route of administration. Intranasal "snorting" is associated with complications secondary to chronic irritation on the nasal mucosa. A case of long-standing intranasal cocaine abuse is presented with unusual complications: septal and palatal necrosis, osteolytic sinusitis and bilateral optic neuropathy. The CT scan demonstrated a soft-tissue mass in etmoid and sphenoidal sinus and orbits. The histopathologic examination revealed a nonspecific pattern of chronic inflammation with no evidence suggestive of infection, neoplasm or lethal midline granuloma. The case had a fatal outcome. Because of the constellation of singular manifestations we discuss the differential diagnosis. Interdisciplinary approach is stressed. Emphasis is made in early diagnosis.

Administration, Intranasal↗

PubMed1993

[The clinical experience in Panama with metronidazole in treating Chagas' disease in the acute and chronic phases].

The authors evaluated the serological response of metronidazole, or 8823 RP-(Hydroxy-2' ethy1)-1-methyl-2 nitro-5 imidazole) in 1307 patients, with Chagas' disease in the acute or chronic stage with age ranging between 6 months to 73 years. 273 patients were in the acute phase: 153 children and 120 adults. Patients in the chronic stage were classified with serological, clinical and cardiological criteria: 1.-POSITIVE SEROLOGY without cardiological signs or symptomatology (EKG, VECTO, ECHO M mode and 2-D, Chest Rx, physiological and pharmacological tests, radiocardiological-HMIBI, MUGA); 2.- POSITIVE SEROLOGY with cardiological signs and symptoms (all cardiological tests were abnormals); 3.- POSITIVE SEROLOGY with cardiomyopathy and cardiac failure. Metronidazole, P.O. or I.V. was utilizing dosages ranging from 15 to 25 mg/Kilo body weight per five days in acute phase and 250 to 500 mg. P.O. in the chronic stage of the disease for 180 days. The drug was well tolerated by all patients in both phases of the disease. Adequate anabolic effect was identified in both stages of the illness. Serological reactions were negative in all patients (100%) without cardiomyopathy. In patients with cardiomyopathy and cardiac failure, the complement fixation test title were similar before and after treatment.

Acute Disease↗

PubMed1991

Evidence that estramustine binds MAP-1A to inhibit type IV collagenase secretion.

Estramustine is a novel anti-microtubule drug shown to bind MAP-1 and MAP-2 (microtubule-associated proteins) in vitro. In this paper we have shown that estramustine specifically binds MAP-1A in Du 145a cells, resulting in disruption of MAP-1A microtubules and inhibition of type IV collagenase secretion. Immunofluorescence studies revealed that at 30 microM levels estramustine blocked type IV collagenase secretion by partial disruption of the MAP-1A microtubule networks. Immunoprecipitation studies with polyclonal antibodies provided quantitative evidence that 30-60 microM estramustine blocked secretion of a 105 x 10(3) Mr type IV collagenase. Pulse-labeling experiments confirmed that the effect was not a result of inhibition of either protein synthesis or altered rates of type IV collagenase turnover. Finally, drug uptake studies with [3H]estramustine, scintillation counting and fluorography demonstrated that the principal target of the drug was MAP-1A. For the first time we have shown that the drug blocks secretion by binding MAP-1A and causing incomplete disruption of the microtubule networks.

Cell Line↗

PubMed1983

Microbiological study of localized juvenile periodontitis in Panama.

The occurrence of subgingival Actinobacillus actinomycetemcomitans and Capnocytophaga in 12 localized juvenile periodontitis and 10 gingivitis patients from Panama was determined using selective culture techniques. A actinomycetemcomitans was present in all localized juvenile periodontitis lesions studied and was, on average, recovered in hundred-fold-higher numbers from localized juvenile periodontitis lesions than from gingivitis lesions. Capnocytophaga was only recovered in approximately threefold-higher numbers from localized juvenile periodontitis than from gingivitis. The study confirms and extends previous data indicating a close relationship between A actinomycetemcomitans and localized juvenile periodontitis. It is proposed that identification of A actinomycetemcomitans may be a valuable adjunct in the diagnosis of localized juvenile periodontitis.

Actinobacillus↗