ISOTRETINOIN-INDUCED CRANIOFACIAL MALFORMATIONS

拟议的研究涉及使用我们已有的一种动物模型 为研究异维甲酸引起的畸形而开发的 (13-顺式维甲酸，Acutane)；畸形，可与 由这种药物在人类身上诱发的那些。自9月份推出以来 1982年，异维甲酸已成为一种广泛使用的非常有效的药物 用于治疗严重的囊性痤疮。与其他人的情况一样 维甲酸(维生素A)，异维甲酸是已知的致畸作用 实验动物。尽管有人警告不要在怀孕期间使用，但 已知的暴露在200到300次之间。在婚前协议中， 已经被允许进入学期，颅面、心脏的发病率很高 胸腺也出现了异常。 我们动物模型中的畸形与人类中看到的非常相似 已经有可能证明对神经的干扰 脊线发育是其发病机制的一个主要特征。此外, 我们有证据表明一种代谢物，4-氧代-异维甲酸(它能达到 血清中母体化合物浓度的3-5倍 接受治疗的患者)也是致畸的。在此应用程序中， 我们建议使用扫描EM完成描述性形态研究， 光学显微镜和透射电子显微镜。一种免疫组织学程序将 被用来协助鉴定神经脊细胞。 异维甲酸和4-氧代异维甲酸的药代动力学研究 已经启动，将完成。对小鼠的维持治疗方案 这两种化合物的血药浓度与人体治疗性药物相似 级别正在开发中。在产妇给药后，水平 胚胎中这些化合物的含量也将得到确定。 关于异维甲酸改变血管紧张素转换酶的机制的进一步研究 在这个模型中，神经脊和其他细胞群的发育 也提出了。其中包括使用~3H-异维甲酸和冰冻切片 放射自显影用于确定化合物是否集中在冠部 其他研究表明处于发育特定阶段的细胞 使用14C-维甲酸(14C-全反式维甲酸)。单元格中的更改 用~3H-胸腺嘧啶核苷放射自显影技术研究细胞增殖。 还将检查纤维连接蛋白和细胞黏附分子的变化。

The proposed studies are concerned with the use of an animal model we have developed for the study of malformations induced by isotretinoin (13-cis-retinoic acid, Accutane); malformations which are comparable to those induced by this drug in humans. Since its introduction in September 1982, isotretinoin has become a widely used drug which is very effective for the treatment of severe cystic acne. As is the case with other retinoids (vitamin A), isotretinoin was known to be teratogenic in experimental animals. Despite warnings against use during pregnancy, there have been between 200 and 300 known exposures. In the prenancies which have been permitted to go to term, high incidences of craniofacial, heart and thymic abnormalities have occurred. Malformations in our animal model are very similar to those seen in human newborns and it has been possible to show that interference with neural crest development is a major feature in their pathogenesis. In addition, we have evidence that a metabolite, 4-oxo-isotretinoin (which reaches concentrations 3-5 times that of the parent compound in the serum of patients undergoing treatment) is also teratogenic. In this application, we propose to complete descriptive morphological studies using scanning EM, light microscopy and transmission EM. An immunohistological procedure will be utilized to assist in the identification of neural crest cells. Pharmacokinetic studies of isotretinoin and 4-oxo-isotretinoin which have been initiated will be completed. Regimens for maintenance in mice of blood levels of both compounds which are similar to human therapeutic levels are being developed. Following maternal administration, the levels of these compounds in the embryos will also be determined. Further studies concerning the mechanisms by which isotretinoin alters the development of neural crest and other cell populations in this model are also proposed. These include the use of 3H-isotretinoin and frozen section autoradiography to determine whether the compound is concentrated in crest cells at certain stages of their development as suggested by other studies using 14C-tretinoin (14C-all-transretinoic acid). Alterations in cell proliferation will be studied using 3H-thymidine autoradiography. Alterations in fibronectin and cell adhesion molecule will also be examined.