MACROMOLECULAR ADDUCTS DOSIMETRY

我们将讨论化学剂量(暴露)对吸收的影响， 人体膳食的代谢活化和DNA加合动力学 杂环胺。我们的目标是确定类型和意义 在饮食中预期的暴露水平下发生的DNA损伤。我们会 重点研究氨基咪唑氮芳烃(AIA)杂环化合物 烹调过程中在肉类中形成的ppb级的胺。这些 化学品在细菌突变检测中是强有力的诱变剂，并且 在小鼠、大鼠和灵长类动物中最大限度地进行生物检测时会致癌 耐受剂量。因为它们是在肉类中形成的，所以被广泛消费 被美国公众接受，并可能构成重大的健康风险。而这些 最近已证明化合物在最大程度上是致癌的。 耐受性剂量，必须以低得多的水平评估真正的健康意义 接触水平，并推算到人类。为了回答这些问题，我们 将把传统的分子剂量学方法与一种新的超 放射性同位素检测的灵敏技术。这项新技术， 加速器质谱仪(AMS)将被用来定义 实际环境暴露下的毒物动力学和DNA加合物剂量测定 在啮齿动物模型中的水平。我们将比较剂量对新陈代谢的影响 在啮齿类动物和人类组织中的激活。32P-贴标签将 用于验证该方法，并识别和确定 主要DNA加合物与致突变和染色体的关系 损坏。我们还将综合和确定 主要的加合物。最后，将数据用于风险评估模型，以 估计接触这些物质所带来的遗传和癌症风险 化合物。我们已经合成了新陈代谢中间体 AIAS，并建立了体外和体内模型以研究其激活作用 DNA损伤中间体的AIAS。我们已经开发了方法论来 AMS在DNA加合物剂量测定中的应用我们的合作者已经开发出方法 评估细胞遗传学和代谢参数，并发展风险 估计。这些工具将很容易地组合在一起，并适应 这里感兴趣的杂环胺致癌物质。通过以下途径获得的数据 这一建议对于理解两者之间的关系非常重要 暴露、DNA加合物形成、DNA加合物数量和修复，以及 DNA加合物在实际水平上的遗传毒性 曝光。最重要的是，这些数据将用于评估风险 由食用一组杂环胺致癌物质引起的 在美国人的饮食中很普遍。

We will address the effects of chemical dose (exposure) on the absorption, metabolic activation, and DNA adduct kinetics for human dietary heterocyclic amines. Our goal is to determine the types and significance of DNA damage occurring at exposure levels expected from the diet. We will focus our investigations on the amino-imidazoazaarene (AIA) heterocyclic amines which are formed in meat at the ppb level during cooking. These chemicals are potent mutagens in bacterial mutation assays and are carcinogenic in mice, rats, and primates when bioassayed at the maximally tolerated doses. Since these are formed in meat they are widely consumed by the American public and may pose a substantial health risk. While these compounds have recently been shown to be carcinogenic at the maximum tolerated dose, the true health significance must be assessed at much lower exposure levels and extrapolated to humans. To answer these questions we will combine traditional methods of molecular dosimetry with a new ultra- sensitive technique for radioisotope detection. This new technique, accelerator mass spectrometry (AMS), will be used to define the toxicokinetics and DNA adduct dosimetry at actual environmental exposure levels in rodent models. We will compare the effects of dose on metabolic activation in rodents and in human tissue fractions. 32P-postlabeling will be used to validate the methodology and to identify and determine the relationships of the major DNA adducts to mutagenesis and chromosomal damage. We will also synthesize and determine the structural nature of the major adducts. Finally, the data will be used in risk assessment models to estimate the genetic and cancer risk posed from exposure to these compounds. We have already synthesized metabolic intermediates of the AIAs, and developed in vitro and in vivo models to study the activation of the AIAs to DNA damaging intermediates. We have developed methodology to use AMS in DNA adduct dosimetry. Our collaborators have developed methods to assess cytogenetic and metabolic parameters and to develop risk estimates. These tools will be easily combined and adapted to the heterocyclic amine carcinogens of interest here. The data obtained through this proposal will be important to understanding the relationships between exposure, DNA adduct formation, DNA adduct numbers and repair, and the genetic toxicities of DNA adducts at levels caused through actual exposures. Most importantly, this data will be used for assessing the risk posed from consumption of a group of heterocyclic amine carcinogens which are prevalent in the American diet.