RESUMO
BACKGROUND: Few methods are available for transparently combining different evidence streams for chemical risk assessment to reach an integrated conclusion on the probability of causation. Hence, the UK Committees on Toxicity (COT) and on Carcinogenicity (COC) have reviewed current practice and developed guidance on how to achieve this in a transparent manner, using graphical visualisation. METHODS/APPROACH: All lines of evidence, including toxicological, epidemiological, new approach methodologies, and mode of action should be considered, taking account of their strengths/weaknesses in their relative weighting towards a conclusion on the probability of causation. A qualitative estimate of the probability of causation is plotted for each line of evidence and a combined estimate provided. DISCUSSION/CONCLUSIONS: Guidance is provided on integration of multiple lines of evidence for causation, based on current best practice. Qualitative estimates of probability for each line of evidence are plotted graphically. This ensures a deliberative, consensus conclusion on likelihood of causation is reached. It also ensures clear communication of the influence of the different lines of evidence on the overall conclusion on causality. Issues on which advice from the respective Committees is sought varies considerably, hence the guidance is designed to be sufficiently flexible to meet this need.
Assuntos
Probabilidade , Medição de Risco , Humanos , Reino Unido , AnimaisRESUMO
BACKGROUND AND PURPOSE: Due to sensitive neuroimaging techniques, cerebrovascular complications such as cerebral microbleeds (CMB) and cerebral cavernous malformations (CCM) are increasingly recognized as considerable late effects after treatment for pediatric brain tumor. The aim of this study was to analyze CMB in a cohort of patients after cranial irradiation therapy for medulloblastoma or other pediatric brain tumors using susceptibility-weighted magnetic resonance imaging (SWI). MATERIALS AND METHODS: Forty former pediatric brain tumor patients were enrolled in this prospective cross-sectional study and examined by cranial MRI including SWI sequences. Cerebral microbleeds, clinical symptoms and disability were evaluated. RESULTS: Thirty-six (90%) of the examined individuals (mean follow-up age 22.2â¯y; mean follow-up time 13.5â¯y) were affected by CMB. Longer follow-up time and higher craniospinal irradiation doses correlated with higher total lesion count (pâ¯<â¯0.01). Thirteen patients (32.5%) presented with clinical symptoms. Individuals with CMB were more severely disabled than patients without CMB (pâ¯<â¯0.05). CONCLUSIONS: Cerebrovascular sequelae occur frequently after treatment for pediatric brain tumor. In this study, a remarkable part of pediatric brain tumor patients presents with CMB. As a sign of vascular damage, they can cause clinical symptoms and may correspond to neurocognitive decline. Further studies are needed to standardize MRI protocols and to improve quality of long-term follow-up.
Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/radioterapia , Hemorragia Cerebral/diagnóstico por imagem , Irradiação Craniana/efeitos adversos , Lesões por Radiação/diagnóstico por imagem , Adolescente , Adulto , Hemorragia Cerebral/etiologia , Circulação Cerebrovascular/efeitos da radiação , Criança , Pré-Escolar , Irradiação Craniana/métodos , Estudos Transversais , Progressão da Doença , Feminino , Humanos , Lactente , Imageamento por Ressonância Magnética/métodos , Masculino , Neuroimagem/métodos , Estudos Prospectivos , Lesões por Radiação/etiologia , Adulto JovemRESUMO
Azaspiracids (AZAs) are the most recently discovered group of biotoxins and are the cause of azaspiracid shellfish poisoning (AZP) in humans. To date over thirty analogues have been identified. However, toxicological studies of AZAs are limited due to the lack of availability of toxins and toxin standards. Most data available are on acute toxicity and there are no data available on genotoxicity of AZAs. This study presents an integrated approach investigating the genotoxic potential of AZA1-3 in cell culture systems using the Comet assay combined with assays to provide information on possible apoptotic processes, cytotoxicity and changes in cell number. Results demonstrate a time and dose dependent increase in DNA fragmentation in most cell lines, indicating a genotoxic effect of AZA1-3. However, a significant reduction in cell number and a clear shift from early to late apoptosis was observed for all analogues in Jurkat T cells and HepG-2 cells; CaCo-2 cells did not show a clear apoptotic profile. Late apoptotic/necrotic cells correlate well with the percentage of tail DNA for all analogues in all three cell lines. All data taken together indicate that AZA1-3 is not genotoxic per se and demonstrate apoptotic/necrotic processes to be involved to some extent in AZAs toxicity. The sensitivities of cell lines and the different potencies of AZA1-3 are in agreement with the literature available. The order of sensitivity for all three AZAs tested in the present study is, in increasing order, CaCo-2 cells < HepG-2 cells < Jurkat T cells. The order of potency of AZA1-3 varies among the cell lines.
Assuntos
Furanos/toxicidade , Toxinas Marinhas/toxicidade , Mutagênicos/toxicidade , Piranos/toxicidade , Compostos de Espiro/toxicidade , Ensaio Cometa , Células Hep G2 , Humanos , Células JurkatRESUMO
Endocrine disrupting chemicals (EDCs) are introduced into the aquatic environment through industrial and municipal effluents along with urban and agricultural runoffs. Exposure of aquatic organisms to EDCs may lead to hormonal disruption and adverse health effects. The goals of our study were: to collect anchovy and mussel samples from the coastal region of Karachi, to use the yeast estrogen screen (YES) bioassay in estimating xeno-estrogen content in these samples, and to investigate if the bioassay could be used to quantify known amounts of 17ß-estradiol (E2) injected into cod and salmon fillets. Results of the studies showed that mussel estrogenic activity in Karachi decreased in the order of Buleji point 1 (8.91 ± 4.77, mean ± SD) > Paradise point 1 (1.72 ± 0.81) > Paradise point 2 (0.61 ± 0.84) ng E2 equivalents/g wet wt (p < 0.05). By comparison, anchovy estrogenic activity at Korangi/Phitti Creek was much higher than at Manora. Together, these results confirmed previous reports that both Buleji point 1 and Korangi/Phitti Creek were the most contaminated areas of Karachi. The YES bioassay was only a semi-quantitative method in determining the contents of xeno-estrogens in aquatic organisms; it consistently overestimated the amounts of E2 injected into cod and salmon fillets due to additive and/or non-additive interactions between E2 and endogenous estrogens. Nevertheless, the YES bioassay was able to identify the contaminated sites in the coastal region of Karachi.