Simey de Souza Leão Pereira Magnata

Bio: Simey de Souza Leão Pereira Magnata is an academic researcher from Federal University of Pernambuco. The author has contributed to research in topics: Blood proteins & Erythrocyte fragility. The author has an hindex of 3, co-authored 8 publications receiving 19 citations.

Biokinetics and dosimetric studies about 99mTc(V)-DMSA distribution.

Abstract: Research for radiodiagnostic agents should considerate biological critical parameters which will give own contribution on the absorbed dose. The dimercaptosuccinic acid (DMSA) labeled with (99m)Tc(V) is a radiopharmaceutical which has well established role in medullar thyroid carcinoma and has been proposed in evaluation of bone metastasis. This work studied the biokinetics and dosimetry of (99m)Tc(V)-DMSA by animal model. The (99m)Tc(V)-DMSA was prepared from a (III)DMSA kit alkalized. Mice (n=5) received (99m)Tc(V)DMSA i.v., they were sacrificed (30 min, 1h, 5h and 12h), the organs excised and the activities measured by a gamma counter. The results were evaluated based on %activity/g and the absorbed dose was estimated (MIRDOSE 3.0 program) by extrapolation of data from animal to human scale. The results showed the majority of organs reached the top uptake at 30 min, the greatest kidney uptake was (4.81 +/- 1.38)% activity/g, while the bone presented its highest uptake at 1h (5.49+/- 0.47)% activity/g, after 1h all the organs had activity exponential decrease. The biokinetic profile of (99m)Tc(V)-DMSA was well established, allowing quantifying of residence time, and the radiation dose estimates were made for this agent. About the absorbed dose, the preliminary results showed higher value to bone, being the soft tissue dose relatively low.

Effect of the extract of Ricinus communis L. on the osmotic fragility, labeling of red blood cells with Technetium-99m and morphology of the cells

Abstract: The aim of this study was to evaluate the influence of the proteic extract of R. communis on the cell physiology by the osmotic fragility, labeling of the blood elements with the 99mTc and cell morphology. To evaluate the osmotic fragility, the blood samples of the Wistar rats were incubated with the concentrations of R. communis and with the solutions of NaCl (0.4; 0.7; 0.9%). In the labeling of the blood elements procedure, the rat blood was treated with a solution of Tc-99m and TCA at 5%, determining the rate of radioactivity (%ATI) in the plasma (P) and in the red blood cells (RBC). The soluble and insoluble fractions of the plasma were also evaluated. The cells morphology submitted to the extract was evaluated by the optical microscopy (x40). The results indicated that the rate of the hemolysis increased in the presence of 0.125 mg/mL of the extract. There was a decay of 49.69% in the rate of ATI in the insoluble fraction of the cells, with the morphological alterations in the red blood cells. These results suggested that the extract changed the capability of binding of the red blood cells due to the stannous ion oxidation, modifying the cells structure.

Avaliação do controle radioquímico do Ricinus communis L. e Tc-99m na marcação de hemácias

Abstract: O Ricinus communis L. pertence a familia das Euforbiaceas, possui frutos tipicos de onde e extraido o oleo de ricino, altamente toxico. Neste estudo foi analisado o efeito do extrato de Ricinus communis L na marcacao de hemacias com Tc-99m atraves do controle radioquimico. Os resultados mostraram que no controle radioquimico por meio da cromatografia, foi observado que o extrato marcado com Tc-99m mostrou duas fracoes com 130.007 e 494.592 cpm, e na marcacao de hemacias, com %ATI de 61.88 e 41.32% nas fracoes 1 e 2. Foi concluido que o extrato de R. communis L. altera a captacao do Tc-99m in vitro, competindo com o material radioativo em possiveis sitios de ligacao nas celulas vermelhas do sangue, como a capacidade de oxidacao do ion estanoso ou por competicao com o ion pertecnetato.

Unstable chromosome aberrations in peripheral blood lymphocytes from patients with cervical uterine cancer following radiotherapy.

Abstract: Scoring of unstable chromosomes aberrations (dicentrics, rings and fragments) in circulating lymphocytes is the most extensively studied biologic system for estimating individual exposure to ionizing radiation. In this work, blood samples from 5 patients, with cervical uterine cancer, were analyzed by conventional cytogenetic in order to correlate the frequency of chromosome aberrations in lymphocytes with the dose absorbed by the patient, as a result of radiotherapy with 6 0 Co gamma. The samples were collected in three phases of the treatment: before irradiation, 24 hr after receiving 0.08 Gy and 1.8 Gy, respectively. On the basis of the frequencies of unstable aberrations observed, a good agreement was obtained between doses estimated by calibration curve and the doses previously planned to radiotherapy. This report discusses the methodology employed as an important tool for dose assessment as a result of partial-body exposure to ionizing radiation.

Lymph nodes in the irradiated field influence the yield of radiation-induced chromosomal aberrations in lymphocytes from breast cancer patients.

Abstract: Purpose To measure chromosomal aberrations in blood lymphocytes from breast cancer patients treated with radiotherapy after quadrantectomy or tumorectomy. Methods and materials Twenty-two breast cancer patients treated with breast-conserving surgery and radiation were evaluated. Adjuvant chemotherapy was also given to 9 patients. Blood samples were obtained before radiotherapy, after about one-half of the fractions, and at the end of the treatment of the whole breast (50 Gy). Chromosome aberrations in peripheral blood lymphocytes were measured using chemical-induced premature chromosome condensation combined with fluorescence in situ hybridization. Results Radiation treatment produced a significant increase in the yield of chromosomal aberrations. A large interindividual variability was observed. The variability was not related to field size, previous chemotherapy, or treatment morbidity. Chromosome aberrations in lymphocytes at the end of the treatment were significantly higher in the group of patients with no lymph nodes surgically removed before the treatment than in the group of patients with more than 10 lymph nodes removed. Conclusions The number of lymph nodes within the radiation field is an important factor affecting the yield of radiation-induced chromosomal aberrations in breast cancer patients.

Unstable chromosomal aberrations and micronuclei analyses in the biomonitoring of workers occupationally exposed to ionising radiation

Abstract: The quantification of unstable chromosomal aberrations and micronuclei in peripheral blood lymphocytes is a method commonly used in biodosimetry by cytogenetic analysis, especially when physical dosimetry cannot be performed. In this context, the aim of this research was to compare these methods in the biomonitoring of health professionals occupationally exposed to ionising radiation. In parallel, the C-banding technique was applied to confirm the presence of unstable chromosomal aberrations (dicentrics and rings). For this, samples of peripheral blood from health professionals of three hospitals (Recife – Brazil) were collected and lymphocyte cultures were carried out based on classical cytogenetic techniques. The number of cells scored per subject was the same (1000) for each assay. Among the individuals, those who do not usually wear a lead apron had higher frequencies of unstable chromosomal aberrations and micronuclei than the ones who carefully observe the radioprotection rules.

Assessment of the effect of Bacopa monnieri (L.) Wettst. extract on the labeling of blood elements with technetium-99m and on the morphology of red blood cells

Abstract: Bacopa monnieri (L.) Wettst. (BM), a traditional Ayurvedic medicine, used for centuries as a memory enhancing, anti-inflammatory, antipyretic, sedative and antiepileptic agent. BM extract have been extensively investigated by several authors for their neuropharmacological effects. In nuclear medicine, red blood cells (RBC) labeled with technetium-99m (99mTc) have several clinical applications. However, data have demonstrated that synthetic or natural drugs could modify the labeling of RBC with 99mTc. As Bacopa monnieri is extensively used in medicine, we evaluated its influence on the labeling of RBC and plasma proteins using technetium-99m (99mTc). This labeling procedure depends on a reducing agent and usually stannous chloride is used. Blood was incubated with BM extracts. Stannous chloride solution and 99mTc were added. Blood was centrifuged and plasma (P) and blood cells (BC) were isolated. Samples of P or BC were also precipitated, centrifuged and insoluble fraction (IF) and soluble fraction (SF) were separated. The percentage of radioactivity (%ATI) in BC, IF-BC and IF-P were calculated. The %ATI significantly decreased on BC from 95.53±0.45 to 35.41±0.44, on IF-P from 80.20±1.16 to 7.40±0.69 and on IF-BC from 73.31±1.76 to 21.26±1.40. The morphology study of RBC revealed important morphological alterations due to treatment with BM extracts. We suggest that the BM extract effect could be explained by an inhibition of the stannous and pertechnetate ions or oxidation of the stannous ion or by damages induced in the plasma membrane.