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平民的人的重大关切。四亚甲基二磺基四胺（TMDT）构成重大威胁。TMDT是一种有效的神经毒性化学品，在全球范围内用作灭鼠剂，直到相关危害导致其停止使用。虽然其生产、销售和使用已被禁止，但在中华人民共和国广泛使用，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病预防控制中心的高度关注。TMDT具有许多特性，使其成为大规模中毒的理想化学品。作为一种水溶性、无臭、无味的物质，它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， 从容易获得的起始材料廉价且容易地合成。它具有急性毒性，并具有长期影响。目前还没有已知的特异性解毒剂。TMDT是一种结构上与印防己毒素相关的笼状惊厥药，并阻断GABAA受体复合物的Cl-离子载体作为作用机制。我们的初步研究结果表明，TMDT诱导的综合征包括急性发作（阵挛性和强直-阵挛性）和癫痫相关的死亡和迟发性癫痫发作与致命的结果。与GABAA受体增强剂（地西泮）相比，NMDA受体拮抗剂（氯胺酮）可更好地预防致死性结局。我们的假设是TMDT通过与GABAA受体-氯离子载体复合物结合来阻断Cl-内流，从而导致膜超极化的丧失、突触后神经元的超兴奋性和[Ca 2 +]i的持续增加。具体目标待定：目标1：建立并应用脑神经元培养筛选来识别TMDT对策。1A.测量TMDT诱发的原代大脑皮层细胞培养物中[Ca++]I的变化，并建立可靠的、经验证的条件，用于体外评价TMDT作用的候选对策。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，对它们的TMDT拮抗剂活性进行排名。目的2：在体内小鼠模型中检查TMDT的短期和长期效应，并测试针对TMDT作用的潜在对策。2A.在体内从GABAAR激动剂和NMDAR拮抗剂类别中筛选多种药物，对它们的TMDT拮抗剂活性进行排名。2B.检查所选药物对延迟TMDT毒性的保护作用。2C.确定TMDT诱导综合征的再激发。这项研究将导致直接的体外筛选试验，以揭示对TMDT综合征有效的治疗方法。该体外筛选的分级将与体内试验中确定的药物疗效分级相关，以确认有效性。我们的研究结果将确定现成的治疗短期和预防长期毒性的疗法，从FDA批准的药物。这将提高紧急情况下对接触TMDT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.