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Biomedical subjects

H A Carvalho

Publications and source records attributed to H A Carvalho.

5 recordsLinked to original sources
PubMed2002

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays.

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of São Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable.

Clone Cells↗
PubMed1999

Exploring the clastogenic effects of air pollutants in São Paulo (Brazil) using the Tradescantia micronuclei assay.

This study was designed to determine the clastogenicity of particulate matter (aerodynamic diameter smaller than 10 microm) in the urban polluted air in the city of São Paulo. The Tradescantia-micronucleus (Trad-MCN) assay was used throughout this study to evaluate the clastogenicity of the extracts of the particulate matter. Tradescantia pallida (Rose) Hunt. cv. purpurea, an indigenous cultivar, was used in the Trad-MCN assay. The efficacy of this plant material for the Trad-MCN assay was validated with dose-response studies using formaldehyde and beta radiation. Dose-response curves were established with these known mutagens. The extracts of the PM10 particles at concentrations between 5 and 50 ppm induced a dose-related increase in MCN frequencies. The results indicate that T. pallida is equally sensitive to mutagens as the standard Tradescantia clone 4430 or 03 and the particulate matter in the urban air are clastogenic to the chromosomes of this plant. Inhalation of these particles by urban dwellers may affect their health by inducing similar genetic damage.

Air Pollutants↗
PubMed1997

Stereological estimates of the nuclear/cytoplasmic ratio and star volume on fibreoptic biopsies are of prognostic value for survival in a preliminary study of advanced squamous cell carcinoma of the lung.

AIMS: This study evaluated the role of morphometric and clinical parameters in establishing the prognosis of patients submitted to radiotherapy for advanced squamous cell carcinoma of the lung. METHODS AND RESULTS: Morphometric studies were performed by point counting techniques. Forty patients were included in this study. Group 1 patients (n = 22) were those with survival equal to or less than 6 months; group 2 (n = 10) patients had a survival of 7 to 12 months; and group 3 (n = 8) included patients with survival greater than 12 months. To characterize these three groups of patients, models combining categorical and continuous variables were constructed by means of discriminant analysis. Weight loss, histological grade, nuclear/cytoplasmic ratio and star volume of the nuclei were selected during the backward procedure as relevant variables to characterize the three groups of patients. The overall sensitivity of the model was 90%. CONCLUSIONS: Our results indicate that histopathological data may help to predict prognosis in patients with advanced squamous cell lung carcinoma, and encourage the use of morphometric procedures in histopathological analysis of this type of lung tumour.

Adult↗
PubMedDate not supplied

[High dose rate brachytherapy].

The high dose rate brachytherapy uses a single source os 192Ir with 10Ci of nominal activity in a remote afterloading machine. This technique allows an outpatient treatment, without the inconveniences of the conventional low dose rate brachytherapy such as use of general anesthesia, rhachianesthesia, prolonged immobilization, and personal exposition to radiation. The radiotherapy department is now studying 5 basic treatment schemes concerning carcinomas of the uterine cervix, endometrium, lung, esophagus and central nervous system tumors. With the Micro Selectron HDR, 257 treatment sessions were done in 90 patients. Mostly were treated with weekly fractions, receiving a total of three to four treatments each. No complications were observed neither during nor after the procedure. Doses, fraction and ideal associations still have to be studied, so that a higher therapeutic ratio can be reached.

Brachytherapy↗