RESUMO
PURPOSE: After the accidents of nuclear power plants at Chernobyl and at Fukushima, huge amounts of radioactive iodine were released into the atmosphere. METHODS: We reviewed data on the health consequences of these accidents with a focus on thyroid consequences. RESULTS: Among the 2 million children who were living in highly contaminated regions in Belarus, Ukraine and Russia, 7000 cases of thyroid cancer had occurred in 2005. This is the most significant radiation-induced consequence of the Chernobyl accident. The increased incidence of thyroid cancer observed in adult population who lived in these highly contaminated regions is at least in major part related to screening and it is not possible to individualize among these thyroid cancers those that are potentially caused by radiation exposure. For populations who lived outside these regions at the time of the accident, there is no detectable consequence of the radiation exposure on the thyroid gland. Among children who lived nearby the Fukushima power plant in 2011, there is currently no evidence of an increased incidence of thyroid cancer. Ultrasonography screening in these individuals detected a number of thyroid cancers that are probably not related to the accident. Because thyroid cancer is frequent, studies have been carried out to distinguish radiation-induced from their sporadic counterparts, and genomic signatures might be helpful. CONCLUSIONS: The consequences of the Chernobyl accident clearly demonstrate that populations living nearby a nuclear power plant should be protected in case of accident by sheltering, food restrictions and prophylaxis of thyroid irradiation by potassium iodine administration, if the predicted estimated dose to the thyroid gland of children might be >50 mGy. These countermeasures should be applied in priority to children, adolescents and pregnant women; they are safe and effective.
Assuntos
Acidente Nuclear de Chernobyl , Acidente Nuclear de Fukushima , Neoplasias da Glândula Tireoide , Adolescente , Adulto , Criança , Feminino , Humanos , Radioisótopos do Iodo/efeitos adversos , Gravidez , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/etiologia , UcrâniaRESUMO
Cyclin A is a pivotal regulatory protein which, in mammalian cells, is involved in the S phase of the cell cycle. Transcription of the human cyclin A gene is cell cycle regulated through tight control of its promoter. We have previously shown that the ATF/CREB site, present in the cyclin A promoter, mediates transcriptional regulation by cAMP responsive element binding proteins. The main goal of the present study was to investigate whether this site is involved in transcriptional regulation of the gene. We have constructed stable NIH-3T3 cell lines that express the luciferase reporter gene under the control of normal or mutated versions of the cyclin A promoter. We show that the ATF/CREB is required to achieve maximal levels of transcription from the cyclin A promoter starting in late G1. We also show that down-regulation of the cyclin A promoter by p53 does not implicate a direct binding of p53 to its cognate consensus sequence but occurs probably by interference with trans-activating factors. This result suggests that p53 can interfere with transcription of the cyclin A gene, in the absence of a TATA sequence in the promoter.
Assuntos
Proteínas Sanguíneas/fisiologia , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/fisiologia , Ciclinas/genética , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/fisiologia , Ativação Transcricional/genética , Proteína Supressora de Tumor p53/fisiologia , Células 3T3 , Fatores Ativadores da Transcrição , Animais , Sequência de Bases , Sítios de Ligação , Ciclo Celular/fisiologia , Genes Reporter/genética , Humanos , Cinética , Luciferases/biossíntese , Luciferases/genética , Camundongos , Dados de Sequência Molecular , RNA Mensageiro/biossínteseRESUMO
Cytological analysis of microspore embryogenesis during in vitro culture reveals a high mortality in the first week and a latency phase of about one week before the first embryogénic mitosis. Genotypic differences observed during our wheat anther culture do not seem to originate at the induction level but are linked to the different abortion rates.
