VX-induced cell death involves activation of caspase-3 in cultured rat cortical neurons

Exposure of cell cultures to organophosphorous compounds such as VX can result in cell death. However, it is not clear whether VX-induced cell death is necrotic or involves programmed cell death mechanisms. Activation of caspases, a family of cysteine proteases, is often involved in cell death, and in particular, caspase-3 activation appears to be a key event in programmed cell death processes including apoptosis. In this study, we investigated VX-induced neuronal cell death, as well as the underlying mechanism in terms of its effect on caspase-3 activity. Primary cortical neuronal cultures were prepared from gestational days 17 to 19 Sprague Dawley rat fetuses. At maturation, the cells were treated with varying concentrations of VX and cell death was evaluated by lactate dehydrogenase (LDH) release. VX induced an increase in LDH release in a concentration-dependent manner. Morphological VX-induced cell death was also characterized by using nuclear staining with propidium iodide and Hoechst 33342. VX induced a concentration- and time-dependent increase in caspase-3 activation. Caspase-3 activation was also confirmed by the proteolytic cleavage of poly(ADP-ribose)polymerase (PARP), an endogenous caspase-3 substrate. These data suggested that in rat cortical neurons, VX-induced cell death via a programmed cell death pathway that involves changes in caspase-3 protease.     

Electrophysiological correlates of respiratory failure in acute organophosphate poisoning: Evidence for differential roles of muscarinic and nicotinic stimulation

Background. Respiratory failure in acute organophosphate (OP) poisoning can occur early and also relatively late in the clinical course, and the pathophysiology of respiratory failure at these different phases may have important clinical implications. Objective. To compare the electrophysiological findings in patients with early and late respiratory failure following acute OP poisoning. Methods. A prospective observational case series of consenting symptomatic patients with acute OP poisoning were assessed with daily physical examinations and repetitive nerve stimulation (RNS) studies. RNS was done on right and left median and ulnar nerves at 1, 3, 10, 15, 20, and 30 Hz. Outcomes such as need for ventilation and development of intermediate syndrome (IMS) were noted. Early respiratory failure was defined as occurring within 24 hours of ingestion. Results. Seventy-eight patients were recruited for the clinical and electrophysiological study and of those 59 (75.6%) patients had ingested chlorpyrifos. Seven patients developed respiratory failure within 24 hours of ingestion with overt muscarinic signs. They had no electrophysiological abnormalities at median and ulnar nerves before intubation. Three of them later developed “forme fruste” IMS. Five other patients developed late respiratory failure after 24 hours of ingestion, and all of them showed progressive RNS changes indicating severe IMS prior to intubation. Conclusion. The normal RNS in all patients developing early respiratory failure suggests that it is due to a central nervous system (CNS) and muscarinic effect. This emphasizes the need for early rapid atropinisation as a priority, combating the nicotinic effects being less urgent. This is in contrast with the late respiratory failure, which has been shown to be associated with neuromuscular dysfunction. Further studies are needed to quantify CNS and muscarinic dysfunction to assist in the development of better treatments for the severe and early OP poisoning.     

Posterior reversible encephalopathy syndrome in a patient of organophosphate poisoning

A 32-year-old male presented with a history of consuming some organophosphorous compound with suicidal intention. He was treated with atropine, pralidoxime, ventilator support. During stay patient had persistent irritability, tachycardiaand hypertension despite sedation and labetalol infusion. He developed headache, visual blurring hemiparesis and focal seizures. Magnetic resonance imaging of the brain revealed multifocal hyperintensities mainly in subcortical areas of parietal and occipital regions in T2-weighted images, with increased values of Apparent Diffusion Coefficient, suggesting posterior reversible encephalopathy syndrome (PRES). The possibilities of PRES caused by organophosphorous poisoning either due to hypertension caused by autonomic deregulation or direct neurological toxicity has been discussed.     

急性有机磷农药中毒致中间综合征28例临床分析

目的:探讨急性有机磷农药中毒(AOPP)致中间综合征(IMS)的临床表现及诊治方法。方法:对28例IMS患者的临床表现及治疗方法进行回顾性分析。结果:28例患者均先后发生呼吸肌麻痹,均给予气管插管机械通气及足量的复能剂等治疗,10例进行了血液灌流(HP),抢救成功25例,死亡3例。结论:严密观察、早期诊断、及时行机械通气、足量复能剂和血液灌流是抢救成功的关键。     

有机磷中毒的脑CT表现

目的：通过对有机磷杀虫药中毒病人进行颅脑CT检查，观察、分析有机磷杀虫药中毒病人的脑部CT表现。方法：通过对83例有机磷杀虫药中毒病人进行颅脑CT扫描，观察病人的CT表现并对其进行诊断，对脑部异常患者进行随访。结果：83例患者中64％的患者有脑部异常表现，其中10％的病人有基底节及丘脑对称性或不对称性散在的出血，54％的病人急性期表现为脑水肿，随访脑部有脑萎缩、脑软化等CT表现。结论：对有机磷杀虫药中毒病人进行颅脑CT检查，是减少病人后遗症发生及判断预后具有重要的意义。     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

急性有机磷中毒病人气管切开术后排痰的护理

目的研究有机磷农药中毒病人气管切开术后的排痰方法.方法将74例有机磷中毒气管切开病人分为实验组和对照组,实验组加大湿化液剂量,每次滴注为5 ml,每日湿化液量在500ml以上,吸痰管只在气管套管口吸痰,同时配合胸壁加压法.对照组每次湿化液滴注2 ml,每日总量在250 ml.结果实验组并发症发生率,拔管时间,住院天数以及死亡率,与对照组比较差异有显著性意义（P＜0.05）.结论充分湿化气道是气管切开排痰成功的关键.     

重度有机磷农药中毒抢救失败的临床反思

目的：探讨重度有机磷农药中毒抢救失败病例中的误治问题及其产生原因。方法：回顾性分析了7例重度有机磷农药中毒抢救失败病例的病历资料，总结其中存在的误治问题并分析其产生原因。结果：重度有机磷农药中毒抢救中的误治主要表现为清除毒物不彻底；阿托品剂量应用或停药时间不当；胆碱酯酶复能剂使用途径不当；治疗过程中误用了一些抑制胆碱酯酶活性的药物；呼吸衰竭病人机械通气方法不当。其产生的主要原因包括对病人病情的判断错误；医生对某些影响重度有机磷中毒抢救疗效的相关因素缺乏深入了解。结论：正确判断病情是减少重度有机磷中毒抢救中误治发生率的关键。     

气相色谱法同时测定叶菜中16种有机磷农药残留量

目的:建立气相色谱法测定叶类蔬菜中16种有机磷农药残留量的分析方法。方法:蔬菜捣碎用乙腈提取,盐析,用氮吹仪吹干,丙酮溶解定容,采用HP-5毛细管柱分离,FPD检测器测定。结果:16种有机磷类农药能较好地分离,峰面积与其浓度均具有良好线性,低水平加标回收率除了敌敌畏在44.0%～58.8%之间,其余均在62.8%～128.8%之间,高水平加标回收率除了敌敌畏在40.6%～59.2%之间,其余均在69.3%～123.3%之间,相对标准偏差均小于20%。结论:本方法简便、快速、灵敏、准确,可以满足叶类蔬菜中有机磷类农药检测的需要。