Effects of gamma radiation on the vector competence of Aedes aegypti (diptera: Culicidae) to transmit Zika virus.

One of the limitations of the Sterile Insect Technique (SIT), conventionally performed by ionizing radiation, regards separating males from females, which is not 100% effective. Some irradiated females may be released together with males in the field at SIT. The present study aimed to evaluate the influence of ionizing radiation on the ability of Aedes aegypti mosquitoes to transmit the Zika virus after exposing female pupae to a 40 Gy of gamma radiation. The results suggest that the genetic damage induced by exposure of females to this dose level promotes their total sterility, but it does not influence their vector competence. However, our data point out that ionizing radiation may decrease the proportion of infective mosquitoes.

Effects of gamma radiation on the reproductive viability of Aedes aegypti and its descendants (Diptera: Culicidae).

This work evaluated the genetic damage in descendants of male pupae of Aedes (Stegomyia) aegypti (Diptera: Culicidae) separately exposed to 20, 30, and 40 Gy of gamma radiation in the context of Sterile Insect Technique (SIT). Despite the transmission of the dominant lethal mutation, the employed dose levels did not promote a marked reduction in adult mosquito emergence and fertility. This study emphasized that semi-sterilizing doses < 50 Gy for SIT of Aedes aegypti are not recommended.

Micronucleus assay for predicting side effects of radiotherapy for cervical cancer.

Radiotherapy (RT) is an important treatment for cervical cancer. The quality of life of patients undergoing RT may be compromised during and following treatment by nausea, diarrhea, vomiting, burns, erythema and fistula. Cytokinesis-block micronucleus (CBMN) assays may be useful for predicting adverse effects of RT for cancer. The CBMN test is easy to perform and is reproducible for screening subjects exposed to ionizing radiation. We investigated the use of the frequency of micronuclei (MN) from peripheral blood samples, irradiated in vitro, as a possible biomarker to predict the side effects of RT in patients with cervical cancer. We used 10 patients with cervical cancer receiving RT and chemotherapy. We found a strong relation between the frequency of MN and the appearance of acute side effects of RT for cervical cancer. We suggest that the methodology presented here may be useful for predicting side effects of RT for patients affected by cervical cancer and who have undergone chemotherapy.

Antibacterial activity of irradiated extracts of Anacardium occidentale L. on multiresistant strains of Staphylococcus aureus.

This study evaluated the antibacterial activity of crude and fractionated leaf extracts of Anacardium occidentale, after receiving 10 kGy from 60Co, against multiresistant strains of Staphylococcus aureus in vitro. Minimum Inhibitory Concentrations-MIC and Minimum Bacteriostatic Concentrations-MBC were respectively assessed by serial microdilution technique in multiwall plates and Petri dishes, against standard strains and clinical isolates of multiresistant S. aureus. The results pointed out a significantly increase of the antibacterial activity of the such extracts after irradiation, emphasizing the role of gamma radiation on leaf extracts of A. occidentale to improve bioactive substances, offering new raw material for antibacterial drugs.

Evaluation of Pb-210 in urine and frequency of micronuclei in exfoliated cells as indicators of exposure to cigarettes.

This study aimed at analyzing the frequency of micronuclei (MN) in exfoliated cells as well as the levels of Pb-210 in urine samples to evaluate the association between the smoking habit and toxic stress of transitional epithelial cells. The frequency of MN was scored from Giemsa-stained slides while exchange resin and beta counting techniques were employed to measure the concentrations of this radioisotope. Urine samples of smokers had levels of Pb-210 up to 158.65 mBq L-1. For nonsmokers, the median was below the detection limit (45 mBq L-1). The analyses of mononucleated cells showed a significant increase of the frequency of MN in smokers when compared to nonsmokers. Statistical tests showed a tight relation between the cigarette consumption and the increase of the frequency of MN, rather than with the levels of Pb-210 present in smoke particles. The results indicate the usefulness of the methodology for the evaluation of human health risks related to chronic contamination with Pb-210.

Active caspase-3 expression levels as bioindicator of individual radiosensitivity.

Several molecules and events involved in cell response to radiation-induced damage have been investigated towards a personalized radiotherapy. Considering the importance of active caspase-3 in the proteolytic cascade that ensures radiation-induced apoptosis execution, this research was designed to evaluate the expression levels of this protein as a bioindicator of individual radiosensitivity. Peripheral blood samples of 10 healthy individuals were gamma-irradiated (cobalt-60 source) with 1, 2 and 4 Gy (control: non-irradiated samples), and active caspase-3 expression levels were measured in lymphocytes, by flow cytometry, ex vivo and after different times of in vitro incubation (24, 48 and 72 hours). Short-term incubation of 24 h was the most adequate condition to evidence correlations between dose radiation and active caspase-3 expression. For each radiation dose, it was observed a significant inter-individual variation in active caspase-3 expression intensity, suggesting that this parameter may be suitable for evidence individual radiosensitivity. The methodology presented and discussed in this work may help to predict healthy tissues response to radiation exposure toward the better patient outcome.

Active caspase-3 expression levels as bioindicator of individual radiosensitivity

ABSTRACT Several molecules and events involved in cell response to radiation-induced damage have been investigated towards a personalized radiotherapy. Considering the importance of active caspase-3 in the proteolytic cascade that ensures radiation-induced apoptosis execution, this research was designed to evaluate the expression levels of this protein as a bioindicator of individual radiosensitivity. Peripheral blood samples of 10 healthy individuals were gamma-irradiated (cobalt-60 source) with 1, 2 and 4 Gy (control: non-irradiated samples), and active caspase-3 expression levels were measured in lymphocytes, by flow cytometry, ex vivo and after different times of in vitro incubation (24, 48 and 72 hours). Short-term incubation of 24 h was the most adequate condition to evidence correlations between dose radiation and active caspase-3 expression. For each radiation dose, it was observed a significant inter-individual variation in active caspase-3 expression intensity, suggesting that this parameter may be suitable for evidence individual radiosensitivity. The methodology presented and discussed in this work may help to predict healthy tissues response to radiation exposure toward the better patient outcome.

Correlation between radiation dose and p53 protein expression levels in human lymphocytes.

The aim of this research was to evaluate the relationship between p53 protein levels and absorbed doses from in vitro irradiated human lymphocytes. For this, samples of blood from 23 donors were irradiated with 0.5; 1; 2; and 4 Gy from a Cobalt-60 source, and the percentages of lymphocytes expressing p53 were scored using Flow Cytometry. The subjects were divided into 3 groups, in accordance with the p53 levels expressed per radiation dose: low (Group I), high (Group II), and excessive levels (Group III). For all groups, the analyses showed that the p53 expression levels increase with the absorbed dose. Particularly for groups I and II, the correlation between this protein expression and the dose follows the linear-quadratic model, such as for radioinduced chromosomal aberrations. In conclusion, our findings indicate possible applications of this approach in evaluating individual radiosensitivity prior to radiotherapeutical procedures as well as in medical surveillance of occupationally exposed workers. Furthermore, due to the rapidity of flow-cytometric analyses, the methodology here employed would play an important role in emergency responses to a large-scale radiation incident where many people may have been exposed.

Non-linear dynamics of chromosome condensation induced by colcemid

This study investigated the dynamical process of chromosome condensation after colcemid treatment. Two pairs of human chromosomes, #2 and #3, were highlighted for the accurate identification by fluorescence in situ hybridization (FISH). A computerized image analysis system was used to measure the lengths of the two pairs of chromosomes averaged over 50 metaphases of different cultures with colcemid (0.5 µg/mL) added either at 3 or 48 h of a total 72 h culture period. For determining whether the process of chromosome condensation was chaotic or random, the algorithm of Detrended Fluctuation Analysis (DFA) was used. In order to evaluate the power of the method, the data were shuffled and DFA was performed again. It was found that colcemid prolonged treatment induced a significantly greater chromosome condensation (p<0.05), and the dynamics of this process was determined by the DFA and showed to be chaotic, with scaling exponents with range values 0.5< α<1.0. When the data were shuffled, the scaling exponent αreduced around to 0.5, which was characteristic of random events. These findings reinforced the idea that colcemid could interfere in some manner with the structure of chromosomes and the dynamics of chromosome condensation was non-linear.

Bioindicators in radiation protection

Biodosimetry is the evaluation of absorbed dose using bioindicators. Among chromosomal aberrations, scoring of dicentrics from peripheral human blood has been used as gold standard for biodosimetry, although in case of large scale incidents its use presents some drawbacks. Advances in technology have led to new investigations allowing or permitting the use of new methods which not only improve this "classical" biodosimetry but permits the design of other bioindicators making possible faster analyses, particularly in events where many persons may have been exposed. This report presents an overview of some recent studies developed by the "Grupo de Estudos em Radioproteção e Radioecologia - GERAR", Nuclear Energy Department of UFPE - Brazil, involving biodosimetry.

Biodosimetria pode ser definida como a avaliação da dose absorvida individualmente usando bioindicadores. Entre as aberrações cromossômicas, a quantificação de discêntricos em sangue periférico humano tem sido usada como padrão ouro in biodosimetria, embora essa técnica possua várias limitações em casos de incidentes envolvendo um grande número de indivíduos. Os avanços tecnológicos têm proporcionado novas ferramentas de investigações, resultando no desenvolvimento de novos métodos com intuito de otimizar essa dosimetria biológica "clássica", bem como na descoberta de novos bioindicadores, com o objetivo de possibilitar avaliação de exposição individual de forma mais rápida, em particular em situações envolvendo grande número de indivíduos expostos. Este texto apresenta um breve relato de alguns dos estudos desenvolvidos pelo Grupo de Estudos em Radioproteção e Radioecologia - GERAR, do Departamento de Energia Nuclear da UFPE - Brasil, associados ao emprego dos "clássicos" e novos bioindicadores em biodosimetria.

Biodosimetry for dose assessment of partial-body exposure: a methodological improvement

This study has explored the possibility of combining culture times with extending the duration for which Colcemid is present in cell culture in order to obtain better dose estimations following partial-body exposures. Irradiated and unirradiated blood was mixed to simulate a partial-exposure. Dicentric frequencies and resultant dose estimations were compared from 48 and 72 h cultures with Colcemid added at the beginning, after 24 h or for the final 3 h. The frequencies of dicentrics in first division cells increased with the cell culture time, providing better dose estimations. Unwanted excessive contraction of chromosomes caused by prolonged contact with Colcemid was measured and ways to avoid this are discussed. It is suggested that the combination of a lower than usual concentration of this drug combined with its earlier addition and longer culture time may provide metaphases better suited for interpreting partial-body exposures.

Este trabalho avaliou a estimativa da dose de radiação simulando uma exposição parcial do corpo através da irradiação in vitro de amostras de sangue misturadas com amostras não irradiadas. Foi observado que o prolongamento do tempo de cultura permite que a real fração de linfócitos em M1 contendo aberrações cromossômicas seja detectada, propiciando melhores estimativas de dose, sem a necessidade de correções matemáticas.

Flow cytometry protocol to evaluate ionizing radiation effects on P-glycoprotein activity

The aim of this work was to establish a protocol to evaluate ionizing radiation effects on P-glycoprotein (P-gp) activity. For this, human peripheral blood samples were irradiated in vitro with different doses and P-gp activity was analyzed for CD4 and CD8 T lymphocytes through rhodamine123-efflux assay by flow cytometry. By simultaneous employment of percentage and mean fluorescence index parameters, subject-by-subject analysis pointed out changes in P-gp activity for some individuals and irradiated samples. Based on this work, the proposed protocol was considered adequate for evaluating P-gp activity on cells after radioactive stress. Besides, this research suggests that P-gp activity could be an important factor to define patient-specific protocols in combined chemo-and radiotherapy, particularly when radiation exposure precedes chemical treatment.

O objetivo deste trabalho foi estabelecer um protocolo para avaliar o efeito da radiação ionizante na atividade da glicoproteína-P (gp-P). Para isto, amostras de sangue periférico humano foram irradiadas in vitro com diferentes doses, e a atividade da gp-P foi analisada para os linfócitos T CD4 e CD8 através do ensaio do efluxo da rodamina123 por citometria de fluxo. Por emprego simultâneo dos parâmetros de porcentagem e índice médio de fluorescência, a análise indivíduo por indivíduo apontou mudanças na atividade da gp-P para alguns indivíduos e amostras irradiadas. Com base neste trabalho, o protocolo proposto foi considerado adequado para avaliar a atividade da gp-P em células após estresse radioativo. Além disso, esta pesquisa sugere que a atividade da gp-P poderia ser um importante fator para definir protocolos paciente-específicos envolvendo quimio e radioterapia, particularmente quando a exposição à radiação precede o tratamento químico.

p53 protein expression levels as bioindicator of individual exposure to ionizing radiation by flow cytometry.

Ionizing radiation (IR) can cause various lesions in DNA, which induce the increase of p53 expression levels in order to repair radiation induced damage. Thus, the correlation between the increase of p53 expression and an irradiation may constitute a fast and powerful method of individual monitoring in cases of accidental or suspected exposures to IR. In this context, the aim of this research was to evaluate changes in lymphocyte p53 expression levels, based on flow cytometry, after in vitro irradiation of peripheral blood samples. For the measurement of such expression levels of p53 protein, an investigation was carried out in order to establish a methodology of analysis based on flow cytometry. Hence, relationships among levels of expression of p53 protein with the absorbed dose have been verified. The results presented in this report emphasized flow cytometry as an important tool for the fast evaluation of p53 protein expression levels as bioindicator of individual exposure to acute ionizing radiation.

Dose absorbed by technologists in positron emission tomography procedures with FDG

The objective of this work was to evaluate radiation doses delivered to technologists engaged in different tasks involving positron emission tomography (PET) studies with FDG (fluorodeoxyglucose). This investigation was performed in two French nuclear medicine departments, which presented significant differences in their arrangements and radiation safety conditions. Both centers administered about 300 MBq per PET/CT study, although only one of them is a dedicated clinical PET center. Dose equivalent Hp(10) and skin dose Hp(0.07) were measured using Siemens electronic personnel dosimeters. For assessment dose absorbed by hands during drawing up of tracer and injection into the patient, a Polimaster wristwatch gamma dosimeter was employed. Absorbed dose and the time spent during each investigated task were recorded for a total of 180 whole-body PET studies. In this report, the methodology employed, the results and their radioprotection issues are presented as well as discussed.

O objetivo deste trabalho foi o de avaliar doses absorvidas por profissionais de saúde em diferentes tarefas relacionadas à tomografia por emissão de pósitrons com [18F]-FDG (fluordesoxiglicose). Esta pesquisa foi realizada em dois centros de medicina nuclear na França, os quais apresentavam diferenças significativas em sua organização e radioproteção. Esses centros aplicavam aproximadamente 300 MBq por exame PET/CT, embora apenas um deles correspondesse a um serviço de medicina nuclear dedicado a exames por PET. A dose equivalente (Hp(10)) e a dose na pele Hp(0,07) foram medidas usando dosímetros eletrônicos (Siemens). Para avaliação da dose nas mãos do tecnologista durante a preparação do radiofármaco e durante injeção no paciente, um dosímetro tipo relógio de pulso (Polimaster) foi empregado. A dose absorvida e o tempo empregado durante cada tarefa foram registrados para um total de 180 exames de corpo inteiro através da PET. Neste trabalho, a metodologia empregada, os resultados e suas conseqüências na dose absorvida para o profissional de saúde são apresentados e discutidos.

Physical and biological dosimetry for risk perception in radioprotection

The increase in ionizing radiation (IR) applications, especially nuclear, has been followed by the growth of public concern for the potential associated risks. The publicÆs perception of such risks is often based on the philosophy that IR is harmful at any exposure level. On the other hand, although radiation workers have knowledge about the nature of IR and its potential health effects, the relationship between absorbed dose and risk is not well understood, principally for low doses. This report presents an overview of physical and biological dosimetry as complementary methodologies, as well as their possible contribution for improving risk perception in radioprotection.

O crescente aumento das aplicações das radiações ionizantes, em particular as radiações de origem nuclear, tem sido acompanhado pelo aumento do interesse público em relação aos riscos associados a essas aplicações. A percepção de tais riscos por parte da população é freqüentemente baseada na filosofia que a radiação ionizante é perigosa independentemente dos níveis de exposição. Por outro lado, apesar dos trabalhadores ocupacionalmente expostos terem conhecimento da natureza da IR e seus possíveis efeitos á saúde, a relação entre dose absorvida e risco não é bem entendida por estes, em particular para baixos valores de dose. Este artigo resume aspectos da dosimetria física e biológica como metodologias complementares na melhoria da percepção dos riscos em radioproteção.

Dose assessment by quantification of chromosome aberrations and micronuclei in peripheral blood lymphocytes from patients exposed to gamma radiation

Scoring of unstable chromosome aberrations (dicentrics, rings and fragments) and micronuclei in circulating lymphocytes are the most extensively studied biological means for estimating individual exposure to ionizing radiation (IR), which can be used as complementary methods to physical dosimetry or when the latter cannot be performed. In this work, the quantification of the frequencies of chromosome aberrations and micronuclei were carried out based on cytogenetic analyses of peripheral blood samples from 5 patients with cervical uterine cancer following radiotherapy in order to evaluate the absorbed dose as a result of partial-body exposure to 60Co source. Blood samples were collected from each patient in three phases of the treatment: before irradiation, 24 h after receiving 0.08 Gy and 1.8 Gy, respectively. The results presented in this report emphasize biological dosimetry, employing the quantification of chromosome aberrations and micronuclei in lymphocytes from peripheral blood, as an important methodology of dose assessment for either whole or partial-body exposure to IR.

Estudo morfológico das entero-anastomoses com suturas em pontos separados complementados com adesivo sintético ou biológico em coelho / Morphologic study of enteroanastomosis with sutures in separated stitches supplementeds with synthetical adhesive or biological adhesive

OBJETIVO: Verificar a eficácia dos adesivos de fibrina e cianoacrilato como coadjunvantes nas anastomoses de intestino delgado de coelhos. MÉTODOS: Oitenta coelhos, linhagem Nova Zelândia, machos, adultos, foram submetidos a enterectomia de 3cm e enterorrafia e distribuídos em quatro grupos: Grupo A (dois pontos eqüidistantes); Grupo B (quatro pontos eqüidistantes); Grupo C (seis pontos eqüidistantes); Grupo D (oito pontos eqüidistantes). No 14º dia de observação, os animais foram submetidos a uma laparotomia mediana para estudo macroscópico da cavidade abdominal para identificação e avaliação de aderências, deiscências e/ou fístulas. O segmento intestinal anastomosado foi retirado e feito um molde de alginato para posterior avaliação do índice de estenose. As peças retiradas foram processadas para estudo histológico e avaliação de fibras colágenas, macrófagos, neovascularização e granuloma tipo corpo estranho. RESULTADOS: Não houve diferença significante na avaliação de deiscência e fístulas com os dois adesivos entre os quatros sub-grupos. A aderência ocorreu em maior número nos sub-grupos do adesivo sintético. O índice de estenose foi maior nos animais do adesivo sintético somente nos sub-grupos com dois e oito pontos. A análise histológica mostrou que em todos os parâmetros avaliados (macrófago, neovascularização e granuloma) não houve diferença significante entre os dois tipos de adesivos. Em relação a porcentagem de colágeno verificou-se que houve diferença significante somente no grupo B em que o adesivo sintético foi menor que o biológico. CONCLUSAO: O adesivo biológico de fibrina mostra mais eficácia que o adesivo sintético como complemento de suturas nas anastomoses intestinais.

Trends in biological dosimetry: an overview

Biological dosimetry (biodosimetry) is based on investigations of induced biological effects (biomarkers) in order to correlate them with radiation dose. Among the indicators employed in biodosimetry, scoring of chromosome aberrations is the most reliable method to quantify individual exposure to ionizing radiation. The technique, applied to circulating lymphocytes, has been developed into a routine procedure to evaluate the dose in the case of real or suspected accidental exposure. Considering the radiosensitivity of lymphocytes in vitro and in vivo as being the same, the dose effect relationship obtained after in vitro irradiation of blood has been widely used, with medico-legal value, for evaluating individual radiation exposure. This report presents an overview of strengths, limitations and perspectives on biodosimetry

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

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 60Co 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.

Estudo da resposta de fotodiodos para dosimetria beta / Study of response of photodiode to beta dosimetry

Neste trabalho foram analisadas as respostas dos fotodiodos comerciais SFH-206, BPY-12 e BPW-34 para uso em dosimetria beta. O resultado obtidos mostram que as respostas destes fotodiodos variam linearmente com a dose, apresentando um desvio menor que 1 por cento. O fotodiodo BPY-12 demonstrou ser mais sensível à radiação do que os outros dois fotodiodos estudados.