NUCLEAR MAGNETIC RESONANCE AND EMBRYONIC DEVELOPMENT

核磁共振成像是一种强大的诊断工具， 广泛的潜在应用。目前，关于这一问题的文献 核磁共振的生物效应是不完整的，不确定的，主要局限于 成熟的动物。评估核磁共振风险的研究太少了。 在发育过程中暴露。因为发育中的胎儿是最容易受影响的 对致畸剂，并可能对静态和动态的地图头盔反应， 以及在核磁共振期间射频辐射产生的组织加热 曝光。核磁共振相对安全性的系统研究 在发育过程中需要暴露。建议的研究将 确定：1)任何关键的敏感期；2)统计 发生任何结构异常；3)任何功能和行为 发育过程中核磁共振暴露后的异常。此外, 核磁共振对发育中的神经系统的影响，一个器官系统 是否对任何畸形症病原体最敏感，将进行调查。更多 具体地说，核磁共振对三个关键过程的影响使仪式成为 将对高度精确的神经系统进行评估：1)神经的迁移 脊细胞；2)轴突生长的投射模式和时间；3) 特殊的突触形成。 对任何科学研究都至关重要的是实验模型系统。在这 研究表明，鸡胚具有明显的优势。1)OVO中 胚胎不受母体宿主的影响而发生反应 直接用于致畸剂；2)可以使用大样本群体 以提供统计上有意义的结果；3)鸡胚胎已经 在所有阶段中仔细描述 开发，允许识别随后发生的任何更改 核磁共振暴露；4)鹌鹑细胞可作为天然标记用于研究 神经峰迁移。最终，小鸡交感系统被选中。 对于神经发育的研究，因为：1)相比起来没有那么复杂 中枢神经系统；2)广泛的发育研究 已经在我们实验室完成了；3)人的交感系统 雏鸟与哺乳动物的雏鸟相似。 这项研究的具体目标将以非常敏感的方式进行 将对技术和结果进行盲目分析，以避免偏见。 将对形态异常进行显微镜检查和分析 根据既定的发展标准。行为测试将会是 录在录像带上并仔细分析。关于发展中的问题的研究 神经系统将利用我们的常规技术 实验室。因此，神经脊细胞的迁移模式将是 是由一种鹌鹑-雏鸟移植技术决定的。轴突投射 将用辣根过氧化物酶(HRP)轴突追踪技术标记 并将确定特定神经节细胞的神经支配模式 通过细胞内记录技术。这项系统研究的结果 应为核磁共振风险评估提供重要的数据基础 在胚胎发育过程中暴露。

Nuclear magnetic resonance (NMR) imaging is a powerful diagnostic tool with widespread potential applications. Currently, the literature on the bioeffects of NMR is incomplete, inconclusive, and mostly confined to mature animals. Too few studies have been done to evaluate the risks of NMR exposure during development. Since the developing fetus is most susceptible to teratogenic agents, and may react to static and dynamic mapetic helds, and to tissue heating produced by radiofrequency radiation during NMR exposure. a systematic study to investigate the relative safety of NMR exposure during development is required. Tbe proposed research will determine: 1) any critical periods of sensitivity; 2) the statistical occurrence of any structural abnormality; 3) any functional and behavioral abnormalities subsequent to NMR exposure during development. In addition, the effects of NMR on the developing nervous system, an organ system that is most suseeptible to any teratogeztic agenu, will be investigated. More specifically, NMR effects on three critical processes that give rite to the highly precise nervous system will be evaluated: 1) the migration of neural crest cells; 2) the projection pattem and timing of axonal growth; 3) specific synapse formation. Crucial to any scientific study is the experimental model system. In this study, the chick embryo was chosen for obvious advantages. 1) The in ovo embryo is not affected by a matemal host and reacts directly to teratogenic agents; 2) A large sample population can be used to provide statistically meaningful results; 3) The chick embryo has been carefully described throughout all stages of development, allowing for the identification of any changes subsequent to NMR exposure; 4) Quail cells can be used as natural markers to study neural crest migration. Finally, the chick sympathetic system was chosen for studies of neural development because: 1) It is less complex compared to the central nervous system; 2) Extensive devclopmental studies have already been done in our laboratory; 3) The sympathetic system of the chick is similar to that of the mammal. The specific aims of this research will be pursued with very sensitive techniques and the results will be analyzed blindly to avoid bias. Morphological abnormalities will be microscopically examined and analyzed according to established developmental criteria. Behavioral tests will be recorded on videotape and carefully analyzed. Studies on the developing nervous system wifl utilize techniques that are routine in our laboratory. Thus, the migratory pattem of neural crest celis will be determined by a quail-chick transplantation technique. Axonal projections will be labeled by horseradish peroxidase (HRP) axonal tracing techniques and the pattern of specific ganglion cell innervation will be determined by intracellular recording techniques. Results of this systematic study should provide an important data base for the assessment of risks on NMR exposure during embryonic development.