{"created":"2023-05-15T14:44:21.840598+00:00","id":60657,"links":{},"metadata":{"_buckets":{"deposit":"f21ef3c3-65d3-4c9f-b706-47a4b8ae462f"},"_deposit":{"created_by":1,"id":"60657","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"60657"},"status":"published"},"_oai":{"id":"oai:repo.qst.go.jp:00060657","sets":["10:29"]},"author_link":["601525","601526"],"item_10005_date_7":{"attribute_name":"発表年月日","attribute_value_mlt":[{"subitem_date_issued_datetime":"2004-09-10","subitem_date_issued_type":"Issued"}]},"item_10005_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"In order to estimate the genotoxic risk by low dose radiation, it is essential to distinguish the effect of radiation from that of chemicals. In this presentation I will introduce morphological differences of chromosome aberrations caused by these different agents, and the yield of radiation induced aberrations in comparison to that of other mutagenic factors in the normal living circumstances.\nIonizing radiation is an S (synthetic period in a cell cycle) independent clastogen, while chemical mutagens are S dependent. The peripheral lymphocytes are normally in the Go(non-cycling G1) stage of the cell cycle and they replicate DNA only after being stimulated in the cell culture. When they are exposed to either radiation or chemicals in vivo, their resultant chromosome aberrations are different depending on the clastogens, i. e., the former induces chromosome type aberrations involving both chromatids of chromosomes and the latter induces chromatid type aberrations involving only one of the two chromatids. Thus, they show morphologically different features at the metaphase stage in the first cell division cycle after exposure to those clastogens. But they become indistinguishable in the succeeding cell divisions, because the chromatid type rearrangement is copied on both chromatids (=chromosome type). If a cell has a dicentric accompanied by a fragment which is destined to be lost during cell division, the aberration is considered as a chromosome type aberration in the first cell division cycle. Since most of chemical mutagens induce chromatid type aberrations, a dicentric accompanied by a fragment is an excellent marker of radiation exposures. Dicentrics and translocations are induced in the peripheral lymphocytes in about equal frequency by radiation. The former is unstable to be eliminated through cell division, while the latter is stable to be accumulated in the body. A radiation induced translocation is not distinguished from a chemically induced translocation, and therefore translocations are the indicator of total effects of all kinds of clastogenic factors. Induction yield of dicentrics per cSv with X or gamma rays is reported to be 0.3 per 1000 cells in the human lymphocytes. If the average dose of exposure per year in human body is assumed to be 0.24 cSv, 4.68 dicentrics and 4.68 translocations per 1000 cells would be induced by radiation in the body in 65 years. In general, more than 10 translocations per 1000 lymphocytes in healthy individuals whose ages are around 60 are detected. This value indicates that a significant amount of chromosomal mutations caused by clastogens other than radiation are consistently induced in the human body. The background frequency of one per 1000 is equivalent to the frequency to be induced by the radiation at the dose of about 30 cSv, that is, about two times of the radiation to be received at the age of 65 years in the natural living circumstance.","subitem_description_type":"Abstract"}]},"item_10005_description_6":{"attribute_name":"会議概要（会議名, 開催地, 会期, 主催者等）","attribute_value_mlt":[{"subitem_description":"6th International Conference on High Levels of Natural Radiation and Areas","subitem_description_type":"Other"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"metadata only access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_14cb"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Hayata, Isamu"}],"nameIdentifiers":[{"nameIdentifier":"601525","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"早田 勇","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"601526","nameIdentifierScheme":"WEKO"}]}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"conference object","resourceuri":"http://purl.org/coar/resource_type/c_c94f"}]},"item_title":"Chromosomal mutations by low dose radiation vs those by other mutagenic factors","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Chromosomal mutations by low dose radiation vs those by other mutagenic factors"}]},"item_type_id":"10005","owner":"1","path":["29"],"pubdate":{"attribute_name":"公開日","attribute_value":"2004-11-12"},"publish_date":"2004-11-12","publish_status":"0","recid":"60657","relation_version_is_last":true,"title":["Chromosomal mutations by low dose radiation vs those by other mutagenic factors"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-05-15T21:51:16.167614+00:00"}