Developing and Evaluating Countermeasures Against Tetramethylenedisulfotetramine

描述(由申请人提供)：恐怖袭击平民的威胁仍然是民众和负责保护他们的人的重大关切。毒鼠强(TMDT)构成重大威胁。TMDT是一种强有力的神经毒性化学品，在相关危险导致停止使用之前，曾作为灭鼠剂在全球范围内使用。虽然它的生产、销售和使用已被禁止，但在中华人民共和国中国却随处可见，并与许多意外和故意中毒有关。美国发生的一起严重中毒事件引起了疾控中心的高度关注。TMDT具有许多特性，使其成为一种理想的大规模中毒化学品。它是一种水溶性、无臭、无味的物质，非常适合用于食品和水的掺假。它在环境中也是稳定和持久的，并且可以 从容易获得的原料中廉价且容易地合成。它有剧毒，并有长期影响。目前还没有这种药物的特效解毒剂。TMDT是一种笼状惊厥药，在结构上与印防己毒素有关，并作为一种作用机制阻断GABAA受体复合体的氯离子载体。我们的初步结果表明，TMDT可导致由急性发作(阵挛和强直-阵挛)、癫痫相关死亡和延迟癫痫组成的综合征，并导致致命性后果。与GABAA受体增强剂(安定)相比，NMDA受体拮抗剂(氯胺酮)能更好地预防致命后果。我们的假设是，TMDT通过与GABAA受体-氯离子载体复合体结合来阻断Cl-内流，从而导致膜超极化、突触后神经元的超兴奋性和[Ca~(2+)]i的持续增加。具体目标有待确定：目标1：建立和应用大脑神经元培养筛选，以确定TMDT的对策。1A.测量TMDT引起的原代大脑皮层细胞培养中[Ca++]i的变化，并为体外评估TMDT行动的候选对策建立可靠、有效的条件。1B.从FDA批准的镇静、催眠、抗惊厥、麻醉剂和NMDA受体拮抗剂类别中筛选多种药物，根据它们的TMDT拮抗剂活性对它们进行排序。目的2：在活体小鼠模型中检测TMDT的短期和长期效应，并测试针对TMDT行为的可能对策。2a.在体内从GABAAR激动剂和NMDAR拮抗剂类别中筛选多个药物，根据它们的TMDT拮抗剂活性对它们进行排序。2B。检查选定的药物对延迟性TMDT毒性的保护。2C。确定TMDT诱导的综合征中的再挑战。这项研究将导致直接的体外筛选试验，以揭示治疗TMDT综合征的有效性。这一体外筛选的排名将与体内试验中确定的药物有效性的排名相关。我们的研究结果将确定FDA批准的药物中治疗短期和预防长期毒性的现成疗法。这将增强在紧急情况下对TMDT暴露的医疗反应能力。

DESCRIPTION (provided by applicant): The threat of terrorist attacks on civilians remains a significant concern for the populace and for those charged with their protection. Tetramethylenedisulfotetramine (TMDT) constitutes a significant threat. TMDT is a potent neurotoxic chemical that was available worldwide as a rodenticide until associated hazards led to discontinuance of its use. Although its production, sale, and use have been banned, it is widely available in the Peoples' Republic of China, and has been associated with numerous accidental and intentional poisonings. A severe poisoning in the U.S. was a subject of great attention by the CDC. TMDT has many characteristics that make it a desirable chemical for mass poisoning. Being a water soluble, odorless, and tasteless substance, it is ideally suited to use in adulteration of food and water. It is also stable and persistent in the environment, and can be cheaply and easily synthesized from readily available starting materials. It is acutely toxic, and has long-term effects. There is no known specific antidote to this agent. TMDT is a cage convulsant structurally related to picrotoxin and blocks the Cl- ionophore of the GABAA receptor complex as a mechanism of action. Our preliminary results indicate that TMDT induces a syndrome consisting of acute seizures (clonic and tonic- clonic) and seizure-related death and delayed seizures with lethal outcome. NMDA receptor antagonists (ketamine) better prevented lethal outcome compared to GABAA receptor potentiators (diazepam). Our hypothesis is that TMDT by binding to GABAA Receptor-Chloride Ionophore Complex blocks Cl- influx with consequent loss of membrane hyperpolarization, hyperexcitability of post-synaptic neurons, and sustained increases in [Ca2+]i. Specific Aims to be determined: Aim 1: Establish and apply a cerebral neuronal culture screen to identify TMDT countermeasures. 1A. Measure TMDT-evoked changes in [Ca++]I in primary cerebral cortical cell cultures, and establish reliable, validated conditions for in vitro evaluation of candidate countermeasures for TMDT actions. 1B. Screen multiple agents from FDA-approved sedative- hypnotic-anticonvulsant-anesthetic and NMDA receptor antagonist classes, ranking them for their TMDT- antagonist activity. Aim 2: Examine short- and long-term effects of TMDT in an in vivo mouse model and test potential countermeasures against TMDT actions. 2A. Screen multiple agents from GABAAR agonist and NMDAR antagonist classes in vivo, ranking them for their TMDT-antagonist activity. 2B. Examine selected agents for protection against delayed TMDT toxicity. 2C. Determine re-challenge in the TMDT-induced syndrome. This research will result in straightforward in vitro screen test to reveal treatments effective against the TMDT syndrome. Ranking of this in vitro screen will be correlated to the ranking of efficacy of the drugs determined in the in vivo tests t confirm the validity. Results of our research will identify readily available therapies that treat short-term and prevent long-term toxicity, out of FDA-approved drugs. This will enhance medical response capabilities to TMDT exposure during an emergency.