No description available.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This study’s focus is on the determination and quantization of radiation damage on a cellular level due to the decay of the Auger electron-emitting 123I and the replication of this energy deposition using Geant4 Monte Carlo simulations. The relatively short half-life of 123I (13.2 hours) makes it ideal for studies of Auger electrons which induce biological damage similar to that of high linear energy transfer radiations, when permitted to deposit their energy in close proximity to DNA. Due to small cellular dimensions, direct dose measurements are impossible but estimates may be made from Monte Carlo simulations. In this investigation the thymidine analogue 5-[123I]-iodo-2-deoxyuridine (123IUdR) was used to incorporate the 123I into the cellular DNA of T-lymphocytes from two human donors. Radiation induced micronuclei were numerated in binucleated cells using fluorescence microscopy. The energy deposition per decay of 123I was calculated within a spherical geometry, having the same size and density as a human lymphocyte, using the open source Geant4 toolkit. The absorbed energy per disintegration was used to convert the incorporated 123I activity (Bq) into absorbed dose (Gy) values, in order to compare the biological damage caused by the radioactive iodine to 60Co γ-radiation. A linear relationship between micronuclei frequency and 123I activity could be established. The linear dose-response noted for Auger electrons in the study is indicative of the high-LET nature of these particles. Using the linear-quadratic dose-response curve for micronuclei frequencies following exposure to graded doses of 60Co γ-rays, the relative biological effectiveness (RBE) of the DNA incorporated 123I estimated in this work was found to range from 19 ± 10 to 32 ± 7 for lymphocyte donor 1 and 15 ± 6 to 42 ± 11 for donor 2. The dose limiting RBE (RBEM) for lymphocyte donor 1 and 2 are respectively 34 ± 8 and 50 ± 15 and follows the expected shift in terms of the inherent radiosensitivity of the donors. We also considered the inclusion of the S-phase fraction of the lymphocytes in the dosimetry calculations. The resultant RBEs of the dose points of lymphocyte donor 1 ranges from 4 ± 2 to 7 ± 2, and those of donor 2 ranges from 3 ± 1 to 9 ± 2. The RBEM for lymphocyte donor 1 and 2 are respectively 7 ± 2 and 11 ± 3. The inclusion of the S-phase fraction reduces the calculated RBEs significantly and these observed RBE values relate well to those obtained in studies with fibroblasts and 125IUdR. / AFRIKAANSE OPSOMMING: Hierdie studie fokus op die bepaling en kwantisering van stralingskade op 'n sellulêre vlak as gevolg van die verval van 123I wat Auger elektrone afgee, asook die simulering van hierdie energie afsetting met behulp van die Geant4 Monte Carlo program. Die relatiewe kort half-leeftyd van 123I (13.2 uur) maak dit ideaal vir studies van Auger elektrone wat biologiese skade soortgelyk aan dié van 'n hoë lineêre-energie-oordrag uitstraling veroorsaak, indien die energie van die elektrone naby sellulêre DNA geabsorbeer word. As gevolg van die klein sellulêre dimensies is direkte dosis metings egter onmoontlik, maar skattings kan gemaak word met behulp van Monte Carlo simulasies. Die timidien analoog 5-[123I]-jodo-2-deoxyuridien (123IUdR) was in hierdie ondersoek gebruik om die 123I in die DNA van menslike T-limfosiete in te bou. Mikrokerne in dubbel-kernige selle wat vorm as gevolg van die Auger elektrone was getel met behulp van fluoressensie mikroskopie. Die energie afsetting per 123I verval was bereken binne ‘n sferiese geometrie, met dieselfde grootte en digtheid as 'n menslike limfosiet, met behulp van die Geant4 sagteware. Die geabsorbeerde energie per verval was gebruik om die geïnkorporeerde 123I aktiwiteit (Bq) om te skakel na ‘n waarde van geabsorbeerde dosis (Gy), ten einde die biologiese skade wat veroorsaak word deur die radioaktiewe jodium-123 met kobalt-60 gamma straling te vergelyk. ‘n Lineêre verwantskap tussen die mikrokerne frekwensies en die 123I aktiwiteit is vasgestel. Hierdie verwantskap vir Auger elektrone is 'n aanduiding van die hoë lineêre-energie-oordrag van hierdie deeltjies. Die lineêr-kwadratiese dosis-effek krommes vir mikrokerne frekwensies na blootstelling aan 60Co γ-strale was gebruik om die relatiewe biologiese doeltreffendheid (RBE) van die DNA geïnkorporeerde 123I te beraam. RBE waardes wissel van 19 ± 10 tot 32 ± 7 vir limfosiete van skenker 1 en 15 ± 6 tot 42 ± 11 vir skenker 2. Die dosis beperkte RBE (RBEM) vir limfosiet skenker 1 en 2 is onderskeidelik 34 ± 8 en 50 ± 15 en volg die verwagte skuif in terme van die inherente radiogevoeligheid van die skenkers. Die fraksie van limfosiete wat in S-fase was tydens die blootstelling aan 125IUdR was ingesluit in verdere dosimetrie berekeninge. Die gevolglike RBEs van die dosispunte van limfosiete van skenker 1 wissel van 4 ± 2 tot 7 ± 2 en dié van skenker 2 wissel van 3 ± 1 tot 9 ± 2. Die RBEM vir limfosiet skenker 1 en 2 is onderskeidelik 7 ± 2 en 11 ± 3. Die insluiting van die S-fase fraksie verminder die berekende RBEs aansienlik en die RBE waardes waargeneem hou goed verband met die wat in studies met fibroblaste en 125IUdR verkry is.

Thesis (MScMedSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Background: The assignment of radiation weighting factors to high energy neutron sources is important as there is reason to believe that neutron relative biological effectiveness (RBE) may be related to the inherent radiosensitivity of different individuals. A study was undertaken to quantify the inherent radiosensitivities of lymphocytes obtained from different donors to 60Co y-rays and p(66)/Be neutrons. For this a novel semi-automated image analysis process has been employed. In addition the responses of lymphocytes with different inherent radiosensitivities have also been tested using Auger electrons emitted by 123I. Methods: The RBE of neutrons was determined from dose-response curves for lymphocytes from different donors. Isolated T-lymphocytes irradiated in vitro were cultured to induce micronuclei in binucleated cells and micronuclei (MN) formations numerated using a semi-automated Metafer microscope system. The accuracy in obtaining dose response curves with this method has been tested by evaluating dispersion parameters of MN formations in the response to the different treatment modalities. Differences in the inherent radiosensitivities of cells from different donors were ascertained using 95 % confidence ellipses. [123I]Iododeoxyuridine was prepared in a formulation that allows incorporation of 123I into the DNA of lymphocytes. Micronucleus formations to this treatment were evaluated in lymphocytes with established differences in inherent radiosensitivities. Results: The image analysis system proved to be consistent in detecting micronuclei frequencies in binucleated lymphocytes. As a result, differences in the inherent radiosensitivities of different individuals were distinctive and could be stated at the 95% confidence level. The inter-individual radiosensitivity variations were considerably smaller for blood cells exposed to high energy neutrons compared to 60Co y-rays. Relative biological effectiveness (RBEM) values between 2 and 13 were determined that are highly correlated with the inherent radioresistance of lymphocytes obtained from different individuals. As such radiation weighting factors for high energy neutrons cannot be based on cytogenetic damage determined in lymphocytes from a single donor. Dispersion parameters for micronuclei formations proved to vary according to ionization density. The variation in RBE with neutron dose changed according to theoretical considerations and automated image analysis detection of MN is thus a suitable method to quantify radiation weighting factors. A clear reduction in the variation in radiosensitivity is noted for lymphocytes exposed to Auger electrons compared to 60Co y-rays. The effectiveness of Auger electrons from [123I]IUdR to induce biological damage is demonstrated as the number of disintegrations needed to yield micronuclei formations was found to be more than two orders of magnitude less than that of other compounds. An increase in the RBE of Auger electrons with radioresistance can be inferred from these findings and constitutes a basis for therapeutic gain in treating cells compared to using radioisotopes emitting low-LET radiation. / AFRIKAANSE OPSOMMING: Agtergrond: Die bepaling van straling gewigsfaktore vir hoë energie neutron bronne is belangrik, aangesien daar rede is om te glo dat die relatiewe biologiese effektiwiteit (RBE) kan verband hou met die inherente stralings sensitiwiteit van verskillende individue. Hierdie studie is onderneem om die inherente radiosensitiwiteit van limfosiete verkry vanaf verskillende skenkers te kwantifiseer na blootstelling aan 60Co y -strale en p(66)/Be neutrone. Vir hierdie doel is daar van 'n semi-outomatiese beeldontleding metode gebruik gemaak. Daarbenewens is die reaksie van limfosiete met vooraf bepaalde inherente radiosensitiwiteite ook getoets aan die hand van Auger elektrone wat uitgestraal word deur 123I. Metodiek: Die RBE van neutrone was bepaal uit dosis mikrokerne frekwensie verwantskappe verkry vir limfosiete. Geïsoleerde T-limfosiete was in vitro bestraal en gekweek om mikrokerne te vorm in dubbelkernige selle. Die mikrokerne was gekwantifiseer deur die gebruik van 'n semi-outomatiese Metafer mikroskoop stelsel. Die akkuraatheid in die verkryging van dosis-effek krommes met hierdie metode is getoets deur die ontleding van verspreidings parameters van MN vorming in reaksie op behandeling met die verskillende stralings modaliteite. Verskille in die inherente stralingsensitiwiteite van die selle van verskillende skenkers was vasgestel deur die konstruksie van 95 % betroubaarheidsinterval ellipse. [123I]Iododeoxyuridine was ook berei om 123I in die DNA van limfosiete in te bou. Die mikrokerne vorming op die behandeling is beoordeel in limfosiete met gevestigde verskille in inherent radiosensitiwiteite. Resultate: Die beeld analise stelsel bewys om konsekwent te wees in die opsporing van mikrokerne wat vorm in dubbelkernige limfosiete. Verskille in die inherente radiosensitiwiteite van verskillende skenkers kon vasgestel word op die 95 % betroubaarheidsvlak. Die skommeling in inter-individuele stralings sensitiwiteite was kleiner vir bloed selle blootgestel aan hoë-energie neutrone in vergelyking met 60Co y-strale. Relatiewe biologiese effektiwiteit (RBEM) waardes tussen 2 en 13 is bepaal wat sterk verband hou met die inherente radioweerstandbiedendheid van limfosiete verkry vanaf verskillende persone. As sodanig kan straling gewigsfaktore vir hoë energie neutrone nie gebaseer word op sitogenetiese skade in limfosiete van 'n enkele skenker nie. Verspreidings parameters vir mikrokern vorming het gewissel as ‘n funksie van ionisasiedigtheid van die straling. Die verandering in RBE met neutron dosis verloop volgens teoretiese oorwegings en die semi-outomatiese beeldontledings metode om mikrokerne op te spoor is dus geskik om stralings gewigsfaktore te kwantifiseer. 'n Duidelike afname in die verandering in die stralingsensitiwiteite is waargeneem vir limfosiete blootgestel aan Auger elektrone in vergelyking met 60Co y-strale. Die hoë doeltreffendheid van Auger elektrone afkomstig van [123I]IUdR om biologiese skade te veroorsaak, word weerspieël deur die feit dat die getal disintegrasies wat nodig is om mikrokerne te vorm meer as twee ordes grootte minder is as dié van ander verbindings. 'n Toename in die RBE van Auger elektrone in selle wat radioweerstandbiedend is kan afgelei word uit hierdie bevindinge. Dit vorm 'n basis vir terapeutiese wins in die behandeling van selle in vergelyking met die gebruik van radio-isotope wat lae ionisasie digthede tot stand bring.

No description available.

The primary aim of this study was to determine the effectiveness of array-based technology for detecting and quantifying the presence of mosaicism. This aim was achieved by studying individuals having mosaicism for Down syndrome. SNP arrays were performed on 13 samples from individuals with mosaicism for trisomy 21, 13 samples from individuals with normal chromosome 21complements (negative controls) and 5 samples from individuals with full or partial trisomy 21 (positive controls). In addition, BAC arrays were processed on 6 samples from individuals with mosaicism for trisomy 21, 3 negative controls and 1 positive control. These studies have shown that array-based technology is effective for detecting mosaicism that is present in 20% or more cells with the results being consistent for both platforms. We also demonstrated the strength of array-based technology to identify previously unrecognized chromosomal mosaicism. A second aim of this study was to gain insight regarding the effect that trisomy 21 has on telomere attrition and the frequency of chromosomal instability. This study provides the first reported measure of both chromosome-specific telomere lengths and the frequency of acquired chromosome abnormalities in trisomic cells and isogenic euploid cells obtained from the same individuals. A chromosome-specific telomere length assay was performed on lymphocytes obtained from 24 young individuals with mosaicism for Down syndrome. While differences in overall telomere signal intensities were observed between the euploid and trisomic cells within a person, strikingly similar profiles for chromosome-specific telomere intensities were observed between the cell types within a person. Analyses were also completed on lymphoblast samples obtained from 8 older individuals with mosaicism for Down syndrome, including 5 individuals without dementia and 3 individuals with dementia. In the older study subjects, a significant inverse correlation was observed between telomere length and the frequency of micronuclei, suggesting that telomeric shortening is leading to an increased frequency of chromosomal instability, possibly through dicentric chromosome formation. However, further studies of more individuals, especially additional analyses of older individuals, are needed. These future studies may help to identify genomic regions of interest and serve to inform investigators of potential candidate genes in the etiology of dementia.

In vitro genetic toxicity tests using cultured bacterial or mammalian cells provide a cost- and time-effective alternative to animal tests. Unfortunately, existing in vitro assays are not always reliable. This is in part due to the limited metabolic capacity of the cells used, which is often critical to accurately assess chemical genotoxicity. This limited metabolic capacity necessitates the use of exogenous sources of mammalian metabolic enzymes that can simulate in vivo mammalian metabolic activation reactions. In response to this, and other limitations, alongside the worldwide trend to reduce animal testing, there is an acute need to consider various strategies to improve in vitro mutagenicity assessment. This thesis first examined the utility of exogenous metabolic activation systems based on human hepatic S9, relative to conventional induced rat liver S9, for routine genetic toxicity assessment. This was accomplished by critically evaluating existing literature, as well as new experimental data. The results revealed the limitations of human liver S9 for assessment of chemical mutagenicity. More specifically, the analyses concluded that, due to the increased risk of false negative results, human liver S9 should not be used as a replacement for induced rat liver S9. To address the limitations of conventional mammalian cell genetic toxicity assays that require exogenous hepatic S9, the thesis next evaluated the utility of an in vitro mutagenicity assay based on metabolically-competent primary hepatocytes (PHs) derived from the transgenic MutaMouse. Cultured MutaMouse PHs were thoroughly characterized, and found to temporarily retain the phenotypic attributes of hepatocytes in vivo; they express hepatocyte-specific proteins, exhibit the karyotype of typical hepatocytes, and maintain metabolic activity for at least the first 24 hours after isolation. Preliminary validation of the in vitro MutaMouse PH gene mutation assay, using a panel of thirteen mutagenic and non-mutagenic chemicals, demonstrated excellent sensitivity and specificity. Moreover, inclusion of substances requiring a diverse array of metabolic activation pathways revealed comprehensive metabolic competence. Finally, the thesis further investigated the applicability domain of the in vitro MutaMouse PH assay by challenging the assay with selected azo compounds. Comparison of these results with those obtained using the in vivo MutaMouse TGR (transgenic rodent) assay revealed that MutaMouse PHs can carry out some forms of reductive metabolism. Overall, this thesis demonstrated that a gene mutation assay based on MutaMouse PHs holds great promise for routine assessments of chemical mutagenicity.

O câncer diferenciado da tireoide (CDT) representa cerca de 90% das malignidades tireoidianas com incidência crescente nas últimas décadas. As modalidades de tratamento incluem tireoidectomia, terapia com 131I (com e sem r-hTSH), radio e quimioterapias. Pouco se sabe sobre os efeitos desses tratamentos em nível celular. O presente trabalho foi proposto com o intuito de avaliar em que extensão a terapia com radioiodo pode causar danos em linfócitos periféricos de pacientes com CDT precedidos ou não com r-hTSH, levando-se em consideração, efeitos agudos, tardios e dosimétricos do 131I (estudo in vivo). Um estudo in vitro também foi realizado em células-alvo de tumores tireoidianos (WRO) por meio de análise de citotoxicidade, genotoxicidade e captação do radioiodo. Para tanto, amostras sanguíneas de pacientes, divididos em 2 grupos (grupo A com r-hTSH + 131I e grupo B somente com 131I) foram coletadas antes, 24h, 1 semana, 1 mês e 1 ano após administração do 131I para análise de aberrações cromossômicas (AC). Curva dose-resposta para 131I in vitro foi elaborada para a estimativa de dose absorvida nos pacientes, comparando as frequências de dicêntricos obtidas in vitro com dados in vivo pelo programa Monte Carlo. A iodoterapia induziu um aumento no número de AC em linfócitos de pacientes com valor máximo 24h após o tratamento, com declínio gradativo ao longo do tempo, com mais danos cromossômicos no grupo B em relação ao grupo A, atingindo níveis similares aos basais 1 anos após a administração do radioido. A frequência de dicêntricos encontrada nos linfócitos de pacientes 24h após o tratamento foi equivalente àquela induzida in vitro (0,354 ± 0,153 MBq/mL para o grupo A e 0,309 ± 0,154 MBq/mL para o grupo B), que corresponde a dose absorvida de 0,8 ± 0,3 Gy e 0,7 ± 0,3 Gy para os grupos A e B, respectivamente, sem significância estatística entre os grupos. As células WRO mostraram um ciclo celular relativamente lento de 96,3h com um cariótipo instável. O ensaio genotóxico mostrou uma radiorresistência relativamente alta (0,07 a 3,70 MBq/mL), sem significância estatística com e sem r-hTSH. No entanto, o ensaio citotóxico, mostrou uma tendência à queda nas concentrações mais altas de 1,85 (p<0,05) e 3,70 MBq/mL (p<0,01) somente na presença de r-hTSH, coincidindo com nível mais alto de captação. Células WRO foram relativamente radiorresitentes também à irradiação externa de 60Co na faixa de dose de 0,2 a 8,3 Gy, com queda gradativa em função do tempo para doses mais altas (10, 20 e 40Gy). Dados obtidos mostraram pouco dano citogenético nos pacientes após a exposição terapêutica com radioiodo, o que sugere um tratamento seguro e eficaz para os pacientes dos dois grupos. Pacientes do grupo A, no entanto, obtiveram uma melhor qualidade de vida com o uso do r-hTSH. Estudos in vitro com irradiação interna (131I) e externa (60Co) com ou sem r-hTSH, apontam a necessidade de uma estratégia terapêutica alternativa para contornar a perda da habilidade das células tireoidianas (WRO) em concentrar o radioiodo, responsável pelo relativo insucesso da iodoterapia em pacientes com CDT. / Differentiated thyroid cancer (DTC) represents about 90% of thyroid malignancies with increasing incidence in the recent decades. Treatment modalities include thyroidectomy, 131I therapy (with or without r-hTSH), radio and chemiotherapy. Little is known about the effects of these treatments at the cellular level. This work was proposed in order to assess to what extent radioiodine therapy can cause damage in peripheral lymphocytes of patients with DTC, preceded or not by r-hTSH, taking into account acute, slow and dosimetric effectsof 131I (in vivo study). An in vitro study was also carried out on thyroid tumor target cells (WRO) by cytotoxicity and genotoxicity analysis and radioiodine uptake. For this, blood samples from patients divided into two groups (group A, r-hTSH + 131I and group B,131I only) were collected before, 24 hours, 1 week, 1 month and 1 year after 131I administration for aberration chromosome analysis (CA). A dose-response curve for 131I in vitro was developed for estmating the absorbed dose in patients, comparing the dicentric frequencies obtained in vitro with in vivo data by Monte Carlo program. Radioiodine therapy induced an increase in the number of CA in lymphocytes of patients peaking 24 hours after treatment, with gradual decline over time and with more chromosomal damage in group B than in group A, reaching baseline levels one year afterradioidine administration. The frequency of dicentric found inpatient lymphocytes, 24h after treatment, was equivalent to that induced in vitro (0.354 ± 0.153 MBq / mL for group A and 0.309 ± 0.154 MBq / mL for group B), which corresponds to absorbed doses of 0.8 ± 0.3 Gy and 0.7 ± 0.3 Gy for groups A and B, respectively, with no significant difference between the groups. WRO cells showed a cell cycle relatively slow: 96,3h with an unstable karyotype. The genotoxic test showed a relatively high radioresistance (0.07 to 3.70 MBq/mL), with no statistical significance, with or without r-hTSH. However, the cytotoxic assay, showed a tendency to decrease at higher concentrations of 1.85 (p <0.05) and 3.70 MBq/ml (p <0.01) only in the presence of r-hTSH, coincident with the highest level of uptake. WRO cells were also relatively radioresistant toexternal irradiation of 60Co in the range of 0.2-8.3 Gy, with a gradual decrease in function of time for higher doses (10,20 and 40Gy).The data obtained showed little cytogenetic damage in patients upon therapeutic exposure, suggesting a safe and effective treatment forboth groups of patients. Patients in group A, however, had a better quality of life by using r-hTSH. In vitro studies with internal (131I) and external (60Co)irradiation, with or without r-hTSH, point to the need for an alternative therapeutic strategy to overcome the loss of ability of thyroid cells (WRO) to concentrate radioiodine, wich is responsible for the failure of radioiodine therapy in patients with DTC.

O mecanismo de formação e origem das alterações nucleares ainda é pouco conhecido, sendo o micronúcleo a mais estudada. As células tumorais geralmente apresentam vários tipos de alterações nucleares que estariam associadas à instabilidade genética. O objetivo deste trabalho foi analisar as possíveis associações entre alterações nucleares e citoesqueleto em células HK2 e A549, derivadas de carcinoma de pulmão humano. Otimizamos a metodologia de uso do MCVL para redefinir as alterações nucleares e caracterizar os principais filamentos do citoesqueleto em preparações coradas por Feulgen ou imunofluorescência. As células da linhagem HK2 apresentaram fibras de actina dispostas concentricamente e em "clusters" e os filamentos de tubulina apareceram de forma radial, enquanto que o padrão de distribuição em A549 foi mais semelhante ao das células normais (BRL3A). Os filamentos de lamina B foram os mais importantes para evidenciar as alterações nucleares, porém essas alterações não puderam ser relacionadas com alterações do citoesqueleto. / The origin and mechanism of formation of the nuclear alterations is largely unknown, with the micronucleus being the most well studied alteration. Tumor cells generally present various types of nuclear alterations witch can be associated with genetic instability. The propose of this study was to analyze the possible association between nuclear alterations and the cytoskeleton in the human lung carcinoma cells HK2 and 549. The method of LSM was optimized to redefine the nuclear alterations and to characterize the principal cytoskeletal filaments in preparations stained with Feulgen’s reagent or submitted to imunofluorescent methods. The HK2 cells presented actin fibres arranged either concentrically or in clusters and tubulin filaments arranged radially, while in the A549 cells the distribution pattern was similar to that of normal cells (BRL3A). The lamin B filaments were the most important to identify nuclear alterations, as these alterations could not be related to cytoskeletal alterations.

Made available in DSpace on 2016-08-10T10:53:32Z (GMT). No. of bitstreams: 1 FLAVIA RODRIGUES GOMES FIGUEIREDO.pdf: 6674066 bytes, checksum: d05bac26a9bf315338d0abbf618eaf34 (MD5) Previous issue date: 2012-03-13 / Cochlospermum regium is a typical Cerrado medicinal plant, known as Cotton-docerrado, much used by local people as an analgesic, antiinflammatory, and antibacterial antiedematogenic. However, many chemical constituents of medicinal plants can be toxic and harmful to human health. Therefore, it is necessary to evaluate the potential cytotoxic, mutagenic and genotoxic potential of aqueous extract of this species. With this goal in vivo tests were performed in Poecilia reticulata and in vitro human peripheral blood lymphocytes. Was estimated for both the lethal concentration (CL50/96h) of decoction of C. regium also performed a Micronucleus Test (MN) and comet assay (EC). Tests with P. reticulata were conducted in aquaria with standard acute exposure for 96 hours. The CL50/96h was estimated at 0.25 gL -1. For testing the MN and EC concentrations used were 0.25 gL-1, 0.19 gL-1, 0.13 gL -1 and 0.06 gL-1 in addition to the negative control. As the experimental conditions of the decoction C. 2.2) of± 1.5) and micronuclei (5.6 ±regium showed difference (p = 0.0046 and p = 0.0007) between the concentration of 0.25 gL-1 with an average of (5.5 1.6) respectively, thus showing cytotoxic and mutagenic by micronucleus test.± 1.3) and (2.7 ±erythrocytic nuclear changes with the negative control (2.8 Correlation was observed and linear regression between the positive damage observed in erythrocytes of P. reticulata and the concentrations of the decoction evaluated. However, no genotoxic activity was identified by the comet assay (p = 0.6289 and p = 0.7677) concentrations in any of the parameters for the length of DNA in the comet's tail and quantity of DNA in the comet's tail, also showing no correlation, or simple linear regression between the results obtained and the concentrations tested. For the tests in vitro CL50/96h in human lymphocytes was estimated at 1.73 gL-1. The micronucleus test was performed in whole cultures for 72 hours and comet assay for 3 hours at concentrations of 1.73 gL-1, 1.29 gL-1, 0.86 and 0.43 gL-1 gL -1 of the decoction, CN and CP to methyl methane sulfonate at a 12 concentration of 80ìM and 70 mM respectively. The decoction these concentrations did not differ (p = 0.6235) with the negative control, showing no mutagenic activity in binucleated human lymphocytes, however, correlated and significant linear regression between the concentrations of the decoction and the number of micronuclei observed. For the comet assay, considering the parameters of the comet tail length (p <0.0001) and amount of DNA in the comet's tail (p = 0.0037) difference was observed between the means obtained in human lymphocytes at concentrations of 1, 0.013 0.003) decoction C.± ±73g.L-one (0.46 and 3.98 0.0008), thus demonstrating the potential genotoxicity.± 0.003 ±regium with the average negative control (0.13 and 0.69 It was found that there was strong correlation and linear regression between the measured concentrations and the observed damage. In short, the decoction of C. regium concentrations evaluated in P. reticulata and human lymphocytes showed cytotoxic, genotoxic and mutagenic including concentrationdependent. In this context, due to damage DNA, the decoct this species and its products in the customary conditions is contraindicated for use by the general population. / Cochlospermum regium é uma planta medicinal típica do Cerrado, conhecida como algodãozinho-do-cerrado, muito utilizada pela população como analgésico, antiinflamatório, antiedematogênico e antibacteriano. Porém, muitos constituintes químicos de plantas medicinais podem ser tóxicos e nocivos para a saúde humana. Portanto, faz-se necessário avaliar o potencial citotóxico, genotóxico e mutagênico do extrato aquoso desta espécie. Com este objetivo foram realizados testes in vivo em Poecilia reticulata e in vitro com linfócitos humanos do sangue periférico. Para ambos foi estimada a concentração letal (CL50/96h) do decocto de C. regium, além disso, foram realizados o Teste do Micronúcleo (MN) e o Ensaio Cometa (EC). Os testes com P. reticulata foram realizados em aquários padronizados com exposição aguda por 96h. A CL50/96h foi estimada em 0,25g.L-1. Para os testes do MN e EC foram utilizadas as concentrações de 0,25g.L-1, 0,19g.L-1, 0,13g.L-1 e 0,06g.L-1 além do controle negativo. Conforme as condições experimentais o decocto de C. regium apresentou diferença (p=0,0046 e p=0,0007) entre a concentração de 0,25g.L-1 com média de (5,5±1,5) micronúcleos e (5,6±2,2) de alterações eritrocíticas nucleares com o controle negativo (2,8±1,3) e (2,7±1,6) respectivamente, portanto exibindo ação citotóxica e mutagênica pelo teste do micronúcleo. Foram observadas correlação e regressão linear simples positiva entre os danos observados em eritrócitos de P. reticulata e as concentrações do decocto avaliadas. Porém, não foi identificada atividade genotóxica pelo ensaio cometa (p=0,6289 e p=0,7677) em nenhuma das concentrações para os parâmetros comprimento de DNA na cauda do cometa e quantidade de DNA na cauda do cometa, não apresentando também correlação, nem regressão linear simples entre os resultados obtidos e as concentrações avaliadas. Para os ensaios in vitro a CL50/96h em linfócitos humanos foi estimada em 1,73g.L-1. O teste do micronúcleo foi realizado em culturas 10 completas por 72 horas e ensaio cometa por 3 horas nas concentrações de 1,73g.L- 1, 1,29g.L-1, 0,86g.L-1 e 0,43g.L-1 do decocto, CN e CP com Metil Metano Sulfonato na concentração de 80µM e 70 µM respectivamente. O decocto nestas concentrações não apresentou diferença (p=0,6235) com o controle negativo, não exibindo atividade mutagênica em linfócitos humanos binucleados, entretanto, apresentou correlação e regressão linear simples significativas entre as concentrações do decocto e a quantidade de micronúcleos observados. Para o ensaio cometa, considerando os parâmetros comprimento da cauda do cometa (p<0,0001) e quantidade de DNA na cauda do cometa (p=0,0037) foi observada diferença entre as médias obtidas em linfócitos humanos na concentração de 1,73g.L-1(3,98±0,46 e 0,013±0,003) do decocto de C. regium com as médias do controle negativo (0,69±0,13 e 0,003±0,0008), desta forma demonstrando potencial ação genotóxica. Também foi constatado que houve forte correlação e regressão linear simples entre as concentrações avaliadas e os danos observados. Em suma, o decocto de C. regium nas concentrações avaliadas em P. reticulata e linfócitos humanos apresentou atividades citotóxica, genótoxica e mutagênicas inclusive com relação concentração-dependente. Neste contexto, devido aos danos causados no DNA, o decoto desta espécie e seus produtos nas condições costumeiras é contraindicado para uso geral pela população.

Muitos países possuem estações de pesquisa instaladas na Antártica. Hidrocarbonetos de petróleo e os esgotos lançados no mar pelas estações são as fontes potenciais de poluição na Antártica. Peixes da espécie Trematomus newnesi foram utilizados para investigar o potencial genotóxico e os efeitos sobre a morfologia de fígado e brânquias da água diante dos tanques de combustível e da saída de esgoto da Estação Antártica Brasileira ?Comandante Ferraz?, em experimentos in situ e no laboratório. No Ensaio de Mn e ANE, observou-se que a freqüência de R foi, em geral, menor nos controles do que nos grupos expostos, tanto nos bioensaios como nos experimentos in situ, porém não houve diferenças estatisticamente significativas em nenhum dos experimentos. As lesões branquiais mais observadas, nos grupos expostos, foram hipertrofia do epitélio e telangiectasia lamelar. No fígado, as lesões predominantes foram a vacuolização lipídica e a presença de macrófagos, principalmente nos peixes dos experimentos in situ. Não foram verificadas diferenças significativas nos índices de lesões histopatológicas entre os grupos expostos e os controles em nenhum dos experimentos. Contudo, os resultados obtidos sugerem que dos dois locais analisados nas proximidades da Estação Brasileira, a saída de esgoto apresenta maior potencial de risco para T. newnesi. / Many countries have installed research stations in Antarctica. Petroleum hydrocarbons and the sewage disposed into the sea by the stations are potential sources of pollution in Antarctica. Trematomus newnesi specimens were used to assess genotoxic potential and histopathology of the liver and gills of the water surrounding the Brazilian Antarctic Station ?Comandante Ferraz?. Fish were exposed to seawater at the sewage outfall and in front of the fuel tanks, in both in situ and laboratory assays. The Mn and ENA assay showed that the frequency of R was, in general, lower in the control groups than in the exposed ones in both in situ and laboratory assays, however there were no statistically significative differences in any of the experiments. The most frequent branchial lesions observed in the exposed groups were epithelium hipertrophy and lamelar telangiectasis. In the liver, predominant microscopic findings included lipid vacuolization and macrophages, specially in fish from the in situ experiments. Exposed groups did not show significative differences in the histopathological indexes from those of the controls in any of the experiments. Nevertheless, our results suggest that of the places studied the sewage outlet may present a greater potential of risk to T. newnesi nearby the Brazilian Station.