TWITCHER--A MODEL OF A HUMAN GENETIC NEUROLOGIC DISORDER

抽搐者是最近发现的老鼠的神经突变体。 潜在的遗传缺陷是半乳糖神经酰胺酶缺乏。 的 因此，twitcher是一个遗传和酶的真实模型， 人类球状细胞脑白质营养不良（克拉伯病）。 本 应用程序建议探索这种模式的遗传研究 半乳糖神经酰胺酶缺乏症，绕过罕见和道德 人类疾病的限制。 该研究计划包括三个主要方面 目标. 第一个目标是描述twitcher模型 在成分和代谢上。 详细成分分析 发育大脑，周围神经和肾脏将进行一个 特别强调糖脂的组成， 髓鞘，以及半乳糖基鞘氨醇的可能积累 （精神病）。 突变体也将进行酶法表征。 的 代谢表征将包括半乳糖神经酰胺的合成， 体内和体外，在大脑和肾脏中。 形成和 髓鞘的维持也将用放射性同位素进行研究。 前体 这些基本表征实验的结果将 与人类患者的可用数据进行比较，因为人们不能忽视 潜在的物种差异，即使疾病是由相同的 酶缺乏症 第二个主要目标是净化 正常小鼠半乳糖神经酰胺酶和纯化突变体的尝试 （非活性）酶。 最后一个主要目标是探索几种途径， 通过补充酶来纠正遗传缺陷。 神经移植 实验、正常组织和骨的脑内移植 骨髓移植计划用于体内实验。 此外，本发明还提供了一种方法， 外源性、部分纯化的半乳糖神经酰胺酶和 将在器官型培养物中检查与正常组织的共培养 抽搐的脊髓 酶的科学意义 补充研究，目前，更多的是基本的发展 神经生物学，而不是在不久的将来的临床应用。

The twitcher is a recently discovered neurological mutant of the mouse. The underlying genetic defect is a deficiency of galactosylceramidase. The twitcher therefore is a genetically and enzymatically authentic model of human globoid cell leukodystrophy (Krabbe disease). The present application proposes to explore this model for studies of genetic galactosylceramidase deficiency, bypassing the rarity and the ethical constraints of the human disease. The research plan contains three major goals. The first goal is to characterize the twitcher model compositionally and metabolically. Detailed compositional analysis of developing brain, peripheral nerves and kidney will be carried out with a particular emphasis on the glycolipid composition, the compostion of myelin, and on the possible accumulation of galactosylsphingosine (psychosine). The mutant will also be characterized enzymatically. The metabolic characterization will include synthesis of galactosylceramide in vivo and in vitro, both in the brain and kidney. The formation and maintenance of the myelin sheath will also be studied with radioactive precursors. The results of these basic characterization experiments will be compared with available data on human patients, since one cannot ignore potential species differences even though the disease is caused by the same enzymatic deficiency. The second major goal involves purification of the normal mouse galactosylceramidase and attempts at purifying the mutant (inactive) enzyme. The final major goal is to explore several avenues of correction of the genetic defect by enzyme supplementation. Nerve graft experiments, intracerebral tranplantation of normal tissues, and bone marrow transplantation are planned for in vivo experiments. In addition, effects of exogenous, partially purified galactosylceramidase and of co-culture with normal tissues will be examined in the organotypic cultures of the twitcher spinal cord. The scientific significance of the enzyme supplementation studies is, at present, more of fundamental developmental neurobiology, rather than of clinical applications in the near future.