NTP DATABASE SUMMARIZATION AND EVALUATION

除了发布最新的肿瘤率外， 对照Fischer 344大鼠和B6C3F1小鼠，我们比较了 几种化学物质在NTP啮齿动物体内的评价结果 致癌性研究和转基因小鼠。初步 结果表明，转基因小鼠有可能 作为更快速、更便宜的测试系统来识别 致癌物质。确定了NTP数据库中的12种化学物质 导致鼻腔肿瘤。我们发现大部分的鼻腔 致癌物(1)在两性中都会导致肿瘤增加，(2) 在其他部位也产生了肿瘤，(3)显著减少 在致癌剂量下存活，以及(4)遗传毒性。 最后，我们发现了显著的负相关关系 对照人群脑垂体瘤和睾丸腺瘤的发生率 雄性F344大鼠。在皮肤和吸入研究中，对照组 这两种肿瘤的发病率平均约为65%。在……里面 相比之下，在喂养和灌胃研究中，对照组一直 脑下垂体肿瘤的发病率较低(平均 32%)，以及较高的睾丸肿瘤发生率(平均接近 90%)。可以解释这种反转的一个假设 相关性是与个人住房相关的压力，一种方案 用于皮肤和吸入研究，但不用于喂养和 灌胃研究。

In addition to publishing updated tumor rates in control Fischer 344 rats and B6C3F1 mice, we compared the results of a number of chemicals evaluated both in NTP rodent carcinogenicity studies and in genetically altered mice. Preliminary results indicated that genetically altered mice have the potential to serve as more rapid and less expensive test systems to identify carcinogens. Twelve chemicals in the NTP database were identified that produced nasal cavity tumors. We found that most of the nasal carcinogens (1) produced tumor increases in both sexes, (2) produced tumors at other sites as well, (3) had significantly reduced survival at doses that were carcinogenic, and (4) were genotoxic. Finally, we found a striking inverse correlation between the incidences of pituitary gland tumors and testis adenoma in control male F344 rats. In dermal and inhalation studies, the control group incidences of both tumor types average approximately 65%. In contrast, in feeding and gavage studies, control groups consistently have lower incidences of pituitary gland neoplasms (averaging 32%), and higher incidences of testis tumors (averaging nearly 90%). One hypothesis that could account for this inverse correlation is stress associated with individual housing, a protocol that is used in dermal and inhalation studies, but not in feeding and gavage studies.