Treatment of Organophosphorus Poisoning with 6-Alkoxypyridin-3-ol Quinone Methide Precursors: Resurrection of Methylphosphonate-Aged Acetylcholinesterase

Organophosphorus (OP) nerve agents inhibit acetylcholinesterase (AChE), creating a cholinergic crisis in which death can occur. The phosphylated serine residue spontaneously dealkylates to the OP-aged form, which current therapeutics cannot reverse. Soman's aging half-life is 4.2 min, so immediate recovery (resurrection) of OP-aged AChE is needed. In 2018, we showed pyridin-3-ol-based quinone methide precursors (QMPs) can resurrect OP-aged electric eel AChE in vitro, achieving 2% resurrection after 24 h of incubation (pH 7, 4 mM). We prepared 50 unique 6-alkoxypyridin-3-ol QMPs with 10 alkoxy groups and five amine leaving groups to improve AChE resurrection. These compounds are predicted in silico to cross the blood-brain barrier and treat AChE in the central nervous system. This library resurrected 7.9% activity of OP-aged recombinant human AChE after 24 h at 250 μM, a 4-fold increase from our 2018 report. The best QMP (1b), with a 6-methoxypyridin-3-ol core and a diethylamine leaving group, recovered 20.8% (1 mM), 34% (4 mM), and 42.5% (predicted maximum) of methylphosphonate-aged AChE activity over 24 h. Seven QMPs recovered activity from AChE aged with Soman and a VX degradation product (EA-2192). We hypothesize that QMPs form the quinone methide (QM) to realkylate the phosphylated serine residue as the first step of resurrection. We calculated thermodynamic energetics for QM formation, but there was no trend with the experimental biochemical data. Molecular docking studies revealed that QMP binding to OP-aged AChE is not the determining factor for the observed biochemical trends; thus, QM formation may be enzyme-mediated.

Does organophosphorus poisoning increase the risk of staphylococcal ventilator associated pneumonia? - a retrospective study

INTRODUCTION

The aim of this study was to determine the clinical predictors of staphylococcal ventilator-associated pneumonia (VAP) and to compare the outcomes of staphylococcal VAP with non-staphylococcal VAP.

METHODOLOGY

A retrospective observational study was conducted among adult patients admitted to the medical intensive care unit (MICU) in a tertiary care hospital in India from January 2017 to December 2019. The patients were grouped based on their diagnosis into staphylococcal and non-staphylococcal VAP, and the baseline characteristics, clinical parameters, co-morbidities, and outcome parameters were compared.

RESULTS

Out of 2129 MICU admissions, 456 patients with microbiologically confirmed VAP were included, of which 69 (15.1%) had staphylococcal VAP, and the remaining 387 (84.9%) had non-staphylococcal VAP. Organophosphorus (OP) poisoning was identified as an independent predictor of staphylococcal VAP (odds ratio: 2.57; 95% CI: 1.4 to 4.73). The median duration of mechanical ventilation before VAP diagnosis was less in the staphylococcal VAP group (4 vs. 5 days; p = 0.004). The staphylococcal group also showed a better in-hospital outcome.

CONCLUSIONS

OP poisoning was an independent predictor of staphylococcal VAP. Staphylococcal VAP was diagnosed earlier in patients than non-staphylococcal VAP. Screening for nasal carriage for Staphylococcus, especially in patients with OP poisoning at the time of MICU admission, may help guide antibiotic therapy.

Protective Activity of Novel Hydrophilic Synthetic Neurosteroids on Organophosphate Status Epilepticus-induced Chronic Epileptic Seizures, Non-Convulsive Discharges, High-Frequency Oscillations, and Electrographic Ictal Biomarkers

Nerve agents and organophosphates (OP) are neurotoxic chemicals that induce acute seizures, status epilepticus (SE), and mortality. Long-term neurologic and neurodegenerative effects manifest months to years after OP exposure. Current benzodiazepine anticonvulsants are ineffective in preventing such long-term neurobehavioral and neuropathological changes. New and effective anticonvulsants are needed for OP intoxication, especially for mitigating the long-term sequelae after acute exposure. We developed neurosteroids as novel anticonvulsants and neuroprotectants in OP exposure models. In this study, we evaluated the long-term efficacy of novel synthetic neurosteroids in preventing the development of chronic epilepsy and hyperexcitable ictal events in a rat OP model of SE. Rats were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP), and the experimental groups were treated with the synthetic neurosteroid valaxanolone (VX) or lysaxanolone (LX) 40 minutes post-exposure in conjunction with midazolam. Video-electroencephalography was monitored for two months to assess spontaneous recurrent seizures (SRS), epileptiform discharges, interictal spikes, and high-frequency oscillations (HFOs). Within 60 days of DFP exposure, rats developed chronic epilepsy characterized by frequent SRS, epileptiform discharges, and HFOs. LX treatment was associated with a dose-dependent reduction of epilepsy occurrence and overall seizure burden with a significant decrease in SRS and epileptiform discharges. It also significantly reduced the occurrence of epileptic biomarkers of HFOs and interictal spikes, indicating potential disease-modifying activity. Similarly, the neurosteroid analog VX also significantly attenuated SRS, discharges, HFOs, and ictal events. These results demonstrate the long-term protective effects of synthetic neurosteroids in the OP-exposed post-SE model, indicating their disease-modifying potential to prevent epilepsy and ictal abnormalities. SIGNIFICANCE STATEMENT: The effects of nerve agents and organophosphate (OP) exposure are persistent, and survivors suffer from a number of devastating, chronic neurological dysfunctions. Currently, there is no specific therapy for preventing this disastrous impact of OP exposure. We propose synthetic neurosteroids that activate tonic inhibition provide viable options for preventing the long-term neurological effects of OP intoxication. The results from this study reveal the disease-modifying potential of two novel synthetic neurosteroids in preventing epileptogenesis and chronic epileptic seizures after OP-induced SE.

Evidence Implicating Blood-Brain Barrier Impairment in the Pathogenesis of Acquired Epilepsy following Acute Organophosphate Intoxication

Organophosphate (OP) poisoning can trigger cholinergic crisis, a life-threatening toxidrome that includes seizures and status epilepticus. These acute toxic responses are associated with persistent neuroinflammation and spontaneous recurrent seizures (SRS), also known as acquired epilepsy. Blood-brain barrier (BBB) impairment has recently been proposed as a pathogenic mechanism linking acute OP intoxication to chronic adverse neurologic outcomes. In this review, we briefly describe the cellular and molecular components of the BBB, review evidence of altered BBB integrity following acute OP intoxication, and discuss potential mechanisms by which acute OP intoxication may promote BBB dysfunction. We highlight the complex interplay between neuroinflammation and BBB dysfunction that suggests a positive feedforward interaction. Lastly, we examine research from diverse models and disease states that suggest mechanisms by which loss of BBB integrity may contribute to epileptogenic processes. Collectively, the literature identifies BBB impairment as a convergent mechanism of neurologic disease and justifies further mechanistic research into how acute OP intoxication causes BBB impairment and its role in the pathogenesis of SRS and potentially other long-term neurologic sequelae. Such research is critical for evaluating BBB stabilization as a neuroprotective strategy for mitigating OP-induced epilepsy and possibly seizure disorders of other etiologies. SIGNIFICANCE STATEMENT: Clinical and preclinical studies support a link between blood-brain barrier (BBB) dysfunction and epileptogenesis; however, a causal relationship has been difficult to prove. Mechanistic studies to delineate relationships between BBB dysfunction and epilepsy may provide novel insights into BBB stabilization as a neuroprotective strategy for mitigating epilepsy resulting from acute organophosphate (OP) intoxication and non-OP causes and potentially other adverse neurological conditions associated with acute OP intoxication, such as cognitive impairment.

Acute poisoning by chlorpyrifos differentially impacts survival and cardiorespiratory function in normotensive and hypertensive rats

Hypertension is the most important and well-known risk factor for cardiovascular disease (CVD). Recently, acute organophosphate (OP) poisoning has also been pointed as a CVD risk factor. Despite this evidence, no studies have contrasted the acute toxicosis and cardiovascular (CV) effects of OP poisoning under conditions of normotension and hypertension. In this work, adult male normotensive Wistar and Spontaneously Hypertensive rats (SHR) were intraperitoneally injected with saline or chlorpyrifos (CPF), an OP compound, monitored for acute toxicosis signs and 24-h survival. After poisoning, blood pressure, heart rate and ventilation were recorded, the Bezold-Jarisch Reflex (BJR), the Chemoreflex (CR) were chemically activated, as well as the cardiac autonomic tone (AUT) was assessed. Erythrocyte and brainstem acetylcholinesterase and plasmatic butyrylcholinesterase (BuChE) activities were measured as well as lipid peroxidation, advanced oxidation protein products (AOPP), nitrite/nitrate levels, expression of catalase, TNFα and angiotensin-I converting enzyme (ACE-1) within the brainstem. CPF induced a much more pronounced acute toxicosis and 33 % lethality in SHR. CPF poisoning impaired ventilation in SHR, the BJR reflex responses in Wistar rats, and the chemoreflex tachypneic response in both strains. CPF inhibited activity of cholinesterases in both strains, increased AOPP and nitrite/nitrate levels and expression of TNFα and ACE-1 in the brainstem of Wistar rats. Interestingly, SHR presented a reduced intrinsic BuChE activity, an important bioscavenger. Our findings show that, CPF at sublethal doses in normotensive rats lead to lethality and much more pronounced acute toxicity signs in the SHR. We also showed that cardiorespiratory reflexes were differentially impacted after CPF poisoning in both strains and that the cardiorespiratory disfunction seems to be associated with interference in cholinergic transmission, oxidative stress and inflammation. These results points to an increased susceptibility to acute toxicosis in hypertension, which may impose a significant risk to vulnerable populations.

Pralidoxime-like reactivator with increased lipophilicity - Molecular modeling and in vitro study

Acetylcholinesterase (AChE, EC 3.1.1.7) reactivators (2-PAM, trimedoxime, obidoxime, asoxime) have become an integral part of antidotal treatment in cases of nerve agent and organophosphorus (OP) pesticide poisonings. They are often referred to as specific antidotes due to their ability to restore AChE function when it has been covalently inhibited by an OP compound. Currently available commercial reactivators exhibit limited ability to penetrate the blood-brain barrier, where reactivation of inhibited AChE is crucial. Consequently, there have been numerous efforts to discover more brain-penetrating AChE reactivators. In this study, we examined a derivative of 2-PAM designed to possess increased lipophilicity. This enhanced lipophilicity was achieved through the incorporation of a benzyl group into its molecular structure. Initially, a molecular modeling study was conducted, followed by a comparison of its reactivation efficacy with that of 2-PAM against 10 different AChE inhibitors in vitro. Unfortunately, this relatively significant structural modification of 2-PAM resulted in a decrease in its reactivation potency. Consequently, this derivative cannot be considered as a broad-spectrum AChE reactivator.

Delayed myelopathy in a child following organic phosphate poisoning

We report a rare manifestation of delayed organophosphate (OP) poisoning in a male patient in his early childhood. After initially presenting with a cholinergic crisis after OP exposure, the patient returned 3 weeks later with paraparesis and difficulty with bladder control. The results of the MRI of the spine and brain as well as the nerve conduction studies were normal. Myelopathy induced by OP poisoning should be considered in any patient with a history of OP exposure and a presentation of paraparesis. At most recent follow-up, the patient had full bladder control and could walk without assistance. However, he demonstrated circumduction while walking with upper motor neuron signs. Furthermore, he had mild Achilles tendon contractures on both sides. To enable early detection, neurologists and paediatricians should be aware of this uncommon complication of OP poisoning which may influence neurological outcome.

Detection the severity of organophosphate intoxication using sensitive serum biomarkers S100B and amyloid β (Aβ) in Egyptian subjects

Organophosphate (OP) is a compound considered the main leading cause of morbidity and mortality from poisoning worldwide. Serum pseudocholinesterase was evaluated as a diagnostic indicator; it cannot be used to monitor therapy or severity of the intoxication. The rationale of the current study was to evaluate sensitivity, specificity, and cut-off values of serum S100B and amyloid β for neurological affection severity. This study was carried out on sixty OP-impaired patients; in addition, 20 normal controls were included. Serum liver and kidney function tests, malondialdehyde, pseudocholinesterase, and the levels of S100B and amyloid β (Aβ) were determined. Data showed that Pearson's analysis indicated that the serum level of S100B was positively correlated with Aβ. On the contrary, the activity of pseudocholinesterase was negatively correlated with both of S100B and Aβ. Serum ALT, AST, creatinine, urea, acetylcholine, and MDA levels were elevated while pseudocholinesterase activity was reduced in moderate and severe OP intoxication versus control. A drastic elevation (p<0.001) in the levels of S100B and Aβ was performed in the patient group suffering from OP intoxication versus the normal group. The diagnostic statistical validation of targeted parameters in distinguishing between moderate OP intoxication and control clarifies that S100B displayed the best AUC (0.997) followed by Aβ (AUC=0.992), while the diagnostic veracity of S100B and Aβ in setting apart severe OP-intoxicated and normal subjects stated the symmetric efficacy of potential markers. It was concluded that the significant changes in the levels of S100B and Aβ were directly proportional to the degree of severity of OP intoxication.

Poisoning among Autopsies Conducted in the Department of Forensic Medicine and Toxicology in a Tertiary Care Centre

Introduction

Poisoning is a serious public health issue in developing countries like Nepal. Information about poisoning may be helpful for poisoning prevention and hospital treatment, aiding in the development of measures that lower the morbidity and mortality associated with poisoning. This study aimed to find out the prevalence of poisoning among autopsies conducted in the Department of Forensic Medicine and Toxicology in a tertiary care centre.

Methods

A descriptive cross-sectional study was conducted among autopsied cases in the Department of Forensic Medicine and Toxicology in a tertiary care centre. Data from 1 October 2020 to 1 April 2022 was collected between 22 December 2022 to 30 December 2022 from records after receiving ethical approval from the Institutional Review Committee. All autopsied cases during the study period were included with the exclusion of decomposed bodies. Convenience sampling method was used. The point estimate was calculated at a 95% Confidence Interval.

Results

Among 399 autopsies, 63 (15.79%) (12.21-19.37, 95% Confidence Interval) were found to be cases of poisoning. Among 63 cases, 35 (55.56%) were male and 28 (44.44%) were female. The most common substance causing poisoning was unknown with 31 (49.21%) cases, followed by organophosphates with 24 (38.10%) cases and rodenticide with 8 (12.70%) cases.

Conclusions

The prevalence of poisoning among autopsies was found to be higher than similar studies conducted in similar settings.

Keywords

autopsy; organophosphate poisoning; poisoning; suicide.

An exploratory study; the gap between real reference interval and currently used reference interval of RBC AChE activities in South Korea

The current reference interval (RI) FOR red blood cell acetylcholinesterase (RBC AChE) activity in South Korea was established with data obtained from populations outside the country. The aim of this study was to assess the transferability of current RI of RBC AChE activity for organophosphate (OP) poisoning and determine the biological characteristics, real RI, and interindividual variation in RBC AChE activity in South Korea. Data were retrospectively collected for RBC AChE activity as measured by the modified Ellman's method for 782 patients who presented to our hospital. The clinical course did not differ significantly with the degree of deviation of RBC AChE activity from the currently used RI in 195 patients exposed to OP. RBC AChE activity was associated with gender and smoking status but not age or body mass index (BMI); however, a regression model incorporating age, gender, smoking status and BMI explained only a small portion of the variance in RBC AChE activity in South Korea. The RI of RBC AChE activity was 9,403-16,825 U/L, with 13.9% interindividual variation. The range of RBC AChE activity in South Korea is wider than RI currently used in clinical practice and exhibited a high degree of interindividual variation. In the absence of collecting pre-exposure values, it is recommended to conduct serial measurements, rather than one-point measurements, of RBC AChE activity as evidenced by the RI in OP poisoning.

Lung injury caused by aspiration of organophosphorus insecticide and gastric contents in pigs

INTRODUCTION

Patients who require mechanical ventilation after self-poisoning with ingested organophosphorus (OP) insecticides often die. Aspiration of stomach contents may contribute to lung injury and lethality. This study was designed to assess the severity of direct and indirect pulmonary injury created by pulmonary instillation of mixtures of OP insecticide, solvent (Solv) and porcine gastric juice (GJ) compared to controls.

METHODS

Terminally anaesthetised minipigs (groups n = 5) were exposed to sham bronchoscopy or given mixtures (0.5 mL/kg) of: saline, GJ, OP insecticide and GJ (OP + GJ), or Solv and GJ (Solv + GJ), placed into the right lung, and monitored for 48 h. Lung injury was assessed through analysis of bronchoalveolar lavage fluid (BALF), computed tomography and histopathology.

RESULTS

OP + GJ created a direct lung injury consisting of neutrophil infiltration, oedema and haemorrhage, as well as indirect injury to the other lung. OP + GJ directly-injured lung parenchyma had increased concentrations of BALF protein, albumin, IL-6, IL-8 and C-reactive protein (CRP) at 24 h (p < 0.05), and BALF protein, albumin and CRP at 48 h (p < 0.05), when compared with controls. Aspiration of GJ produced similar direct effects to OP + GJ but less indirect lung injury. Lung injury was less severe after Solv + GJ, for combined lung histopathology scores (vs. OP + GJ, p < 0.05) and for the proportion of directly-injured lung that was poorly/non-aerated at 48 h.

CONCLUSION

Pulmonary instillation of OP + GJ created more lung damage than controls or Solv + GJ. In patients with severe OP insecticide poisoning and reduced consciousness, early airway protection is likely to reduce pulmonary damage.

Comparison between various scoring systems in predicting the need for intensive care unit admission of acute pesticide-poisoned patients

The decision of intensive care unit (ICU) admission in acute pesticide poisoning is often challenging, especially in developing countries with limited resources. This study was conducted to compare the efficacy of the Acute Physiology and Chronic Health Evaluation II (APACHE II), Modified Early Warning Score (MEWS), and Poisoning Severity Score (PSS) in predicting ICU admission and mortality of acute pesticide-poisoned patients. This prospective cohort study included all patients admitted to Tanta University Poison Control Center with acute pesticide poisoning from the start of March 2018 to the end of March 2019. Patient data, including demographic and toxicological data, clinical examination, laboratory investigation, and score values, were collected on admission. Out of 337 acute pesticide-poisoned patients, 30.5% were admitted to the ICU, including those poisoned with aluminum phosphide (ALP) (81.5%) and organophosphates (OP) (18.5%). Most non-survivors (86.6%) were ALP poisoning. The PSS had the best discriminatory power in predicting ICU admission and mortality, followed by APACHE II and MEWS. However, no significant difference in predicting ICU admission of OP-poisoned patients was detected between the scores. Additionally, no significant difference in mortality prediction of ALP-poisoned patients was found between the PSS and APACHE II. The PSS, APACHE II, and MEWS are good discriminators for outcome prediction of acute pesticide poisoning on admission. Although the PSS showed the best performance, MEWS was simpler, more feasible, and practicable in predicting ICU admission of OP-poisoned patients. Moreover, the APACHE II has better sensitivity for mortality prediction of ALP-poisoned patients.

Reducing the risk of death induced by aluminum phosphide poisoning: The new therapies

Numerous people suffer from accidental or deliberate exposure to different pesticides when poisoning with aluminum phosphate (AlP) is increasing in the eastern countries. Aluminum phosphate is a conventional insecticide that quickly reacts with water or the moistures in the atmosphere and produces fatal phosphine gas, which absorbs quickly by the body. Oral consumption or inhalation of AlP leads to excessive reaction of the body such as fatigue, vomiting, fever, palpitation, vasodilatory shock, increasing blood pressure, cardiac dysfunction, pulmonary congestion, shortness of breath, and death. The garlic smell from the patient's mouth or exhale is one of the methods to recognize the positioning. Due to the lack of individual antidotes, several supportive treatments are required. The present study focused on the available and new therapies that help reduce the effect of AlP poisoning and the mortality rate. The therapies are divided into the antioxidant-related agent and the other agents. The impacts of each agent on the experimental cases are reported.

Study of Sick Euthyroid Syndrome in Organophosphate Poisoning

Sick euthyroid syndrome is abnormal findings of thyroid function tests that occur among patients with non thyroid illness with reduced level of hormones like T3 (Triiodothyronine) among acute illness of poisoning and can be detected in blood within 2 hours after acute illness. As the disease progress there is severe manifestation of syndrome associated with hypothyroidism specially with T3 and T4 while, the level of TSH are slightly elevated or are not influenced. The Present study was carried out to assess the incidence of sick euthyroid syndrome in organophosphate poisoning as well to assess the socio demographic and clinical profile of patients with organophosphate poisoning.

MATERIAL

This study was carried out at a tertiary care center for period of one year from January to December 2020 in a sample size of 74 patients(&gt;18 years) admitted in ICU with the history of Organophosphate poisoning. Hemogram and thyroid profile and liver and kidney function of the patients were studied including assessment of gastric aspirates.

OBSERVATION

Out of 74 patients, majority of them were males (62%) in the age group of 21 to 30 years (42%), with organophosphate (64%) followed by carbamates (15%). The incidence of sick euthyroid syndrome with organophosphate poisoning was 53%. The mean serum cholinesterase in poisoning was 913±15.3. The factors which are statistically associated with sick euthyroidism were Male (20 to 40 years), low serum cholinesterase, no prior treatment, ECG changes and miosis.

CONCLUSION

Organophosphate poisoning is more common among young males with incidence of sick euthyroid being quite high among these patients. Pesticide poisoning is more common among young adult males in the age group of 20 to 40 years with the motive of suicidal tendency. The incidence of euthyroidism among organophosphate poisoning is quite high. The biochemical investigations in our study shows an elevation in organophosphate poisoning. This can be used as an indicator to assess the severity of poisoning. The serum cholinesterase and thyroid investigation can also be used as prognostic markers in assessment of severity of organophosphate poisoning. Hence, we conclude that biochemical markers and thyroid investigations helps in assessing mortality and prompt treatment of organophosphate poisoning.

Organophosphorus poisoning in animals and enzymatic antidotes

Organophosphorus compounds (OPs) are neurotoxic molecules developed as pesticides and chemical warfare nerve agents (CWNAs). Most of them are covalent inhibitors of acetylcholinesterase (AChE), a key enzyme in nervous systems, and are therefore responsible for numerous poisonings around the world. Many animal models have been studied over the years in order to decipher the toxicity of OPs and to provide insights for therapeutic and decontamination purposes. Environmental impact on wild animal species has been analyzed to understand the consequences of OP uses in agriculture. In complement, various laboratory models, from invertebrates to aquatic organisms, rodents and primates, have been chosen to study chronic and acute toxicity as well as neurobehavioral impact, immune response, developmental disruption, and other pathological signs. Several decontamination approaches were developed to counteract the poisoning effects of OPs. Among these, enzyme-based strategies are particularly attractive as they allow efficient external decontamination without toxicity or environmental impact and may be of interest for treatment. Approaches using bioscavengers for prophylaxis, treatment, and external decontamination are emphasized and their potential is discussed in the light of toxicological observations from various animal models. The relevance of animal models, regarding their cholinergic system and the abundance of naturally protecting enzymes, is also discussed for better extrapolation of results to human.

Reasons for under-reporting of paraquat poisoning in India

Background Paraquat is an inexpensive herbicide used in agriculture because it is easily available and the cost of labour for manual clearance of weeds is prohibitive. Paraquat is toxic to human beings and is also used for committing suicide. We studied the reasons for under-reporting of paraquat poisoning including those related to the training of doctors. Methods In this mixed-methods study, we describe a series of patients with paraquat poisoning. We recorded their demographic data, clinical features, treatment and outcome with an intention to explore the reason for an initial misdiagnosis. We also explored whether deficiencies in curricula contributed to the misdiagnosis. Results The patients of paraquat poisoning (n=28) were mostly young illiterate men driven by impulsive behaviour rather than chronic depression. Paraquat was consumed by patients from non-agricultural background as well, implying easy access to the poison. Many patients could not name the agent and so initial treatment was directed at organophosphorus poisoning. The diagnostic signs included paraquat tongue, renal failure and jaundice. Most of the casualty medical officers and residents were unfamiliar with the symptoms and signs of paraquat poisoning as was evident by their answers to the questionnaire. Knowledge of medical students about paraquat poisoning was not assessed in the theory examinations and viva. Conclusion Factors contributing to the limitation in establishing the diagnosis are illiteracy and ignorance of the patients, lack of specific signs and lack of training of medical officers in treating patients with paraquat poisoning.

"That's Not His Regular Formula": A Case of Organophosphate Poisoning in an Infant

INTRODUCTION

Organophosphates (OPs) are the basis of many insecticides and herbicides and are also used as nerve agents. Approximately 1 million unintentional and 2 million suicidal poisonings as well as more than 300,000 fatalities that are reportedly due to OPs are reported each year worldwide. The mortality rate from OP toxicity is reported as approximately 20%. We present a rare pediatric exposure to OPs.

CASE

This is an unintentional OP poisoning in an infant who presented to a pediatric emergency department with obtundation, respiratory distress, and copious secretions. The infant was intubated, treated with atropine and pralidoxime after resuscitation, and eventually recovered with no neurologic sequelae.

DISCUSSION

Symptoms from OP toxicity are secondary to effects on muscarinic and nicotinic cholinergic receptors in the autonomic and central nervous systems. Symptoms include diaphoresis, diarrhea, urination, miosis, bradycardia, bronchospasm, bronchorrhea, emesis, lethargy, lacrimation, and salivation. Treatment starts with titrated doses of atropine and oximes (eg, pralidoxime) after resuscitation and decontamination. Severity of toxicity and recovery can be monitored via plasma and whole blood acetylcholinesterase levels, respectively. Once aging has occurred, oximes will not be able to reverse acetylcholinesterase inhibition. Despite early treatment, rare cases may result in delayed neurologic complications associated with sensory and motor axonal degeneration of the peripheral nerves and spinal cord known as OP-induced delayed neuropathy.

CONCLUSIONS

This case highlights the importance of safety education for families. It also demonstrates how to recognize and treat OP toxicity in an infant. It emphasizes starting treatment early to avoid complications secondary to aging.

Unusual aetiology of a type 2 myocardial infarction: a case-based review

Organophosphate pesticide (OP) poisoning is quite common and can cause cardiovascular complications and even direct myocardial injury. However, no guideline has included an acute poisoning as a potential cause for a type 2 myocardial infarction (MI) so far. Here we present a case of a 61-year-old woman brought by ambulance to emergency department one hour after accidental ingestion of an unknown quantity of a solution she used against flea infestation. The patient presented with dizziness, myosis, excessive sweating, hypersalivation, sphincteric incontinence, muscle fasciculation, tremor of the extremities, pale skin, alcoholic and pesticide breath odour. Even though we had no guidelines to fall back on, we successfully treated the patient with low-molecular-weight heparin, antiplatelets, statin, diltiazem, antidote therapy, and supportive care. Physicians should be aware that OP poisoning can induce type 2 MI as a complication within a few hours since exposure, and emergency management should always include close cardiac monitoring.

A rat model of organophosphate-induced status epilepticus and the beneficial effects of EP2 receptor inhibition

This review describes an adult rat model of status epilepticus (SE) induced by diisopropyl fluorophosphate (DFP), and the beneficial outcomes of transient inhibition of the prostaglandin-E2 receptor EP2 with a small molecule antagonist, delayed by 2-4 h after SE onset. Administration of six doses of the selective EP2 antagonist TG6-10-1 over a 2-3 day period accelerates functional recovery, attenuates hippocampal neurodegeneration, neuroinflammation, gliosis and blood-brain barrier leakage, and prevents long-term cognitive deficits without blocking SE itself or altering acute seizure characteristics. This work has provided important information regarding organophosphate-induced seizure related pathologies in adults and revealed the effectiveness of delayed EP2 inhibition to combat these pathologies.

Novichoks - The A group of organophosphorus chemical warfare agents

Novichok use has become symbol for the chemical substances use to carry out political assassinations. In the last century, poisonous warfare agents were used for the first time on the battlefields, almost all over the world. After the World War II, new types of organophosphorus chemical warfare agents were developed. Novichoks are only ones, but the most important part of them - the 4th generation of chemical warfare agents. Despite the Chemical Weapons Convention, entered into force in 1997, there is still real threat of use of chemical weapons. This weapon can be used by both states, and transnational terrorist organisations. Novichoks, A code-named substances, should be permanently introduced into a number of chemical substances contained in organophosphorus chemical warfare poisonous agents. This article presents a short fourth-generation nerve agents' description. Group A compounds together with G and V groups compounds are organophosphorus chemical warfare agents which are very dangerous ones. Our article is an attempt to provide answer for the question - what are Novichoks? And why they should be introduced into Chemical Weapons Convention.

Severe Organophosphate Poisoning with Acute Cholinergic Crisis, Intermediate Syndrome and Organophosphate Induced Long Term Ptosis

Organophosphate compounds are the organic derivatives of Phosphorous containing acids and their clinical effects are due to action on neuromuscular junction and Autonomic Synapses. After exposure these agents cause acute and sub-acute manifestations depending on the type, severity of the agents and duration of presentation, like Acute Cholinergic Manifestations, Intermediate Syndrome (transient palsy) with Nicotinic features and Delayed Central Nervous System Complications. The patient reported here had severe Organophosphate Poisoning complicated by Intermediate Syndrome and Organophosphate Induced long term Ptosis. Highlighting such cases helps increase awareness of health care workers about these rare complications of a common problem.

Total pancreatic necrosis after organophosphate intoxication

Cases of acute pancreatitis induced by organophosphate intoxication are encountered occasionally in clinics, but very few of them develop into severe pancreas necrosis and irreversible pancreatic function impairment. Here, we report a 47-year-old female organophosphate poisoning case after ingestion of massive insecticides; she was considered to have total necrosis and function failure of the pancreas via serum amylase test, glucose level test, and CT imaging. The patient exhibited no relief under the regular medicine treatment, which included sandostatin, antibiotics, intravenous atropine, and pralidoxime methiodide. She received percutaneous catheterization and drainage of pancreatic zone to expel hazardous necrotic waste, also by which the pathogenic evidence was obtained and the antibiotics were adjusted subsequently. The patient recovered gradually, was discharged after 2 weeks, and was prescribed with oral pancreatin capsules before meals and hypodermic insulin at meals and bedtime to compensate the impaired pancreatic function.

A case of suspected brain death within 24 hours after ingestion of tolfenpyrad and an organophosphorus insecticide

A 55-year-old man attempted suicide by ingesting tolfenpyrad, emulsion formulation insecticide, and organophosphorus pesticide emulsion, each three gulps. He was found lying on the floor and his family called an ambulance an hour later from ingesting. On arrival at our hospital, his Glasgow Coma Scale score was 14 (E3V5M6), his vital signs were stable, and he was able to converse. Activated charcoal and laxatives were injected through a gastric tube, and continuous administration of pralidoxime iodide was started. After hospitalization, he complained of nausea and his consciousness level decreased immediately. Endotracheal intubation was performed, and mechanical ventilation management was started Subsequently, he experienced bradycardia leading to transient cardiopulmonary arrest. Return of spontaneous circulation was achieved after one cycle of cardiopulmonary resuscitation. While blood pressure was stabilized with continuous catecholamine administration, blood gas analysis revealed severe lactic acidosis, which gradually aggravated. Electroencephalography performed 16.5 hours after the suicide attempt showed flat waves, and he wa's suspected brain dead. He died about 37 hours after the suicide attempt.

Increased morbidity and mortality in acute human organophosphate-poisoned patients treated by oximes: a meta-analysis of clinical trials

Organophosphates are one of the most common causes of poisoning, especially in the Third world, with high morbidity and mortality. The treatment of this type of poisoning involves the use of atropine and oximes. Atropine has been used successfully in large doses to counteract the muscarinic effects of organophosphate poisoning, but the efficacy of oximes in the management of this poisoning remains under question. In this study, we undertook a meta-analysis by reviewing all clinical trials to evaluate the efficacy of oximes in the management of organophosphate poisoning. The databases of PUBMED, EMBASE, Cochrane, SCOPUS, and the search engine of Google were searched for all clinical trials on the use of oximes in organophosphate poisoning. The inclusion criteria were death, development of intermediate syndrome, and need for ventilation. Six clinical trials met the inclusion criteria and were included in the metaanalysis. The x2 tests for heterogeneity (P–0.25, 0.16, and 0.33, respectively) indicated that the included studies were not significantly heterogeneous and could be combined. A significant relative risk (P–0.0017) for death among oxime-exposed was 2.17 (95% CI of 1.34 / 3.51). The ‘need for ventilation’ in patients who received oxime was higher (P–0.03) than those who did not receive oxime with a relative risk of 1.53 (1.16 / 2.02). The incidence of ‘intermediate syndrome’ for oximeexposed patients was significantly higher (P–0.01) than oxime non-exposed patients with a relative risk of 1.57 (95% CI 1.11 / 2.11). It can be concluded that oximes are not effective in the management of organophosphate-poisoned patients and, surprisingly, they can be dangerous and worsen the patient's clinical situation.

Predicting outcomes in organophosphate poisoning based on APACHE II and modified APACHE II scores

The aim of this study was to evaluate the scores of the Acute Physiology and Chronic Health Evaluation (APACHE) II and a modified APACHE II system (MAS), without parameters of biochemical tests; and to find prognostic value of individual elements of the APACHE II and MAS in predicting outcomes in organophosphate (OP) poisoning. Data were collected from 131 patients. The median (25th—75th percentiles) of APACHE II score for survivors without intubation were found to be lower than those of non survivors or survivors with intubation and ventilation, [4 (1—7); versus 17.5 (7.8—29), and 13.5 (7.8—16.3)]. Logistic regression analysis identified white blood cell (WBC), potassium, Glasgow coma scale (GCS), age and sodium in APACHE II; GCS and mean arterial pressure in MAS system as prognostically valuable. There was no statistically significance difference between APACHE II and MAS scores in terms of area under Receiver Operating Characteristic Curve [(0.902, 95% confidence interval: (0.837—0.947) for APACHE II), and (0.892, 95% confidence interval: (0.826—0.940) for MAS); P = 0.74) to predict need for intubation. It is concluded usage of MAS facilitates the prognostication of the OP poisoned patients due to simplicity, less time-consuming and effectiveness in an emergency situation. Human & Experimental Toxicology (2007) 26: 573—578.

Hyperamylasemia and acute pancreatitis following anticholinesterase poisoning

A prospective study was undertaken to find the incidence of hyperamylasemia and acute pancreatitis in patients with anticholinesterase poisoning. This was done by serial estimation of total serum amylase and pancreatic imaging by ultrasonography and confirmed, if necessary, by computerized tomography. Anticholinesterase poisoning was caused by either ingestion or accidental exposure to organophosphates or carbamates; it was diagnosed when patients presented with features of cholinergic crisis, depressed serum butrylcholinesterase activity of >50% and showed improvement following administration of atropine alone or atropine and 2-PAM. All the patients admitted with anticholinesterase poisoning between July 2001 and June 2005 were prospectively studied for elevated serum amylase. The serum amylase levels were estimated daily up to 10 days in survivors and in nonsurvivors till they survived. Ultrasonography of the abdomen was carried out in all to find swelling of the pancreas. Computerized tomography was undertaken in those who had a swollen pancreas or whose serum amylase levels were elevated significantly (≥800 S.U). Of the 86 patients enrolled, 79 were taken up for analysis as data were incomplete in 7. Of the 79 patients, serum amylase was found to be elevated that is, >200 S.U. in 37 patients (46.95%). In three patients it was 800 S.U. One of them showed swollen pancreas on ultrasonography, which was confirmed by computerized tomography. This patient had ingested propoxyfur. In the other two patients, evidence of acute pancreatitis was not observed (on autopsy in one who died and on imaging in the other who survived). They had ingested chlorpyriphos. There was no significant correlation between the nature of the compounds (organophosphate or carbamates), inhibition of serum BUChE at admission, duration and severity of cholinergic syndrome and increase and time course of increase in serum amylase. Except for fenthion, significant persistent increase in serum amylase was not observed with individual compounds. The other associated abnormalities were polymorphonuclear leukocytosis (TLC >11 000/cumm) in all 37 patients who had elevated amylase, hyperglycemia (6/37) and, elevated transaminases (6/37). Mild elevation of serum amylase is common in patients with anticholinesterase poisoning. However, acute pancreatitis is rare. Human & Experimental Toxicology (2007) 26, 467—471

A simplified acute physiology score in the prediction of acute organophosphate poisoning outcome in an intensive care unit

Organophosphate poisoning (OPP) occurs frequently and accounts for a large number of intoxication cases treated in intensive care units (ICU). Poisoning by these agents is a serious public health problem. Among pesticides, OPs are the main cause of poisoning and death in Loghman-Hakim Poison Center of Tehran, Iran. The aim of this study was to determine the impact of the Simplified Acute Physiology Score (SAPS II) in the prediction of mortality in patients with acute OPP requiring admission to the ICU of Loghman-Hakim Hospital Poison Center over a period of 12 months. This study was a prospective, case-control of records of patients with acute OPP admitted to the ICU between January 2006 and December 2006. The Demographic data were collected and SAPS II score was recorded. During the study period, 24 subjects were admitted to the ICU with acute OPP. All 24 patients (15 male) required endotracheal intubation and mechanical ventilation in addition to gastric decontamination and standard therapy with atropine and oximes and adequate hydration. Of these, 24 patients, eight (five male) died. SAPS II score was significantly higher in the non-survival group than the survival group. Mortality following acute OPP remains high despite adequate intensive care and specific therapy with atropine and oximes. One-third of the subjects needing intensive care die within the hospitalization period. SAPS II scores calculated within the first 24 hours were recognized as good prognostic indicator among patients with acute OPP that required ICU admission. It is concluded that SAPS II score above 11 within the first 24 hours is a predictor of poor outcome in patients with acute OPP requiring ICU admission. Human & Experimental Toxicology (2007) 26, 623—627

Increased Risk of Dementia in Patients With Acute Organophosphate and Carbamate Poisoning: A Nationwide Population-Based Cohort Study

Organophosphate (OP) and carbamate (CM) are the most commonly used pesticides against insects. Little is known regarding the relationship between dementia and acute OP and CM poisoning. A nationwide population-based cohort study was conducted from the National Health Insurance Research Database in Taiwan. The incidence and relative risk of dementia were assessed in patients hospitalized for acute OP and CM poisoning from 2000 to 2011. The comparison cohort was matched with the poisoned cohort at a 4:1 ratio based on age, sex, and the year of hospitalization. During the follow-up period, the incidence of dementia was 29.4 per 10,000 person-years in the poisoned group, and represented a 1.98-fold increased risk of dementia compared with the control cohort (95% confidence interval, 1.59-2.47). This study provides evidence on the association between dementia and acute OP and CM poisoning. Regular follow-up of poisoned patients for dementia is suggested.

[Analyses on relevant factors of the prognosis of patients with acute organophosphate poisoning]

OBJECTIVE

To find out a method which can assess the prognosis of patients with Acute Organophosphate Poisoning objectively and increase the successful ratio of treatment by investigating relevant factors on the prognosis of the patients with Acute Organophosphate Poisoning.

METHODS

We retrospected 116 patients with Acute Organophosphate Poisoning who were treated in our hospital's emergency room from April 2006 to March 2014. According to the outcome of patients, we distributed the patients to death group and survival group, compared the clinic data and using multivariate analysis with Logistic regression to prognosis factors.

RESULTS

116 cases of acute organophosphate poisoning patients died in 23 cases, improved in 93 cases. Death group patients' APACHE-II score are higher than whose in the survival group (P < 0.05). Compared with the survival group, patients' body temperature, blood pressure, pH, GCS index were lower in the death group (P < 0.05) and Cr, WBC, ALT, AST, CK-MB, blood glucose, blood lactic acid, heart rate were higher in the death group (P < 0.05), there were significant difference between two groups with statistical.Low blood pressure, lower GCS score, hyperglycemia and high white blood cell count, were independent risk factors of poor prognosis, and hypotension was maximum value of all the factor (OR = 54.22).

CONCLUSION

APACHE II prognostic scoring system can be accurately response, vital signs, white blood cell count, pH, serum creatinine, GCS score and serum sodium value which in this system may be associated with prognosis. To evaluate the severity and prognosis of illness Blood glucose, ALT, AST, CK-MB's rising also has certain value.

Autonomic function following acute organophosphorus poisoning: a cohort study

Autonomic dysfunction after chronic low level exposure to organophosphorus (OP) pesticides has been consistently reported in the literature, but not following a single acute overdose. In order to study autonomic function after an acute OP overdose, sixty-six overdose patients were compared to 70 matched controls. Assessment of autonomic function was done by heart rate response to standing, deep breathing (HR-DB) and Valsalva manoeuvre; blood pressure (BP) response to standing and sustained hand grip; amplitude and latency of sympathetic skin response (SSR); pupil size and post-void urine volume. The patients were assessed one and six weeks after the exposure. The number of patients who showed abnormal autonomic function compared to standard cut-off values did not show statistically significantly difference from that of controls by Chi-Square test. When compared to the controls at one week the only significant differences consistent with autonomic dysfunction were change of diastolic BP 3 min after standing, HR-DB, SSR-Amplitude, SSR-Latency, post-void urine volume and size of the pupil. At 6 weeks significant recovery of autonomic function was observed and only HR-DB was decreased to a minor degree, −5 beats/min [95%CI 2–8]. This study provides good evidence for the lack of long term autonomic dysfunction following acute exposure to OP pesticides.

Does the nose know? Amitraz poisoning and olfaction

The initial clinical presentation of amitraz and organophosphate poisoning may be similar. Reduced serum pseudocholinesterase supports a diagnosis of organophosphate toxicity, but there is no similar laboratory test for amitraz poisoning. A 'mothball-like' odour associated with poisoned patients may have diagnostic potential. In a blinded controlled trial, 83% (95% confidence interval, 63% to 93%) of 23 healthcare workers were able to distinguish between the odours of amitraz and organophosphate. Awareness of this simple component of bedside examination may allow earlier recognition of this potentially fatal poisoning.

ECG manifestations in acute organophosphorus poisoning

A cross-sectional study was conducted to evaluate the electrocardiographic changes in 107 patients of acute organophosphorus poisoning admitted at casuality ward of MGM Medical College, Kisanganj from June 2007 to June 2010. Electrocardiographic changes were recorded before the administration of atropine. Prolonged Q-Tc interval was the commonest ECG abnormality, found in 67 patients (62.6%), followed by sinus tachycardia in 36 patients (33.6%). Sinus bradycardia was found in 33 patients (30.8%). Elevation of ST segment was seen in 27 patients (25.2%). T wave inversion was seen in 21 patients (19.6%). First-degree heart block (P-R interval >0.20 seconds) occurred in 9 cases (8.4%). Atrial fibrillation was seen in 5 patients (4.6%). Ventricular tachycardia was seen in 6 cases (5.6%) and ventricular premature complexes in 3 patients (2.8%). Of these 6 cases of ventricular tachycardia 1 responded to intravenous lignocaine, and the other 5 developed ventricular fibrillation leading to death despite other resuscitative measures. All the electrocardiographical abnormalities returned to normal before the patients were discharged. Seventeen patients died. The cause of death was ventricular fibrillation in 5 patients and non-cardiogenic pulmonary oedema in others. In conclusion it can be said that ECG should be carefully recorded and analysed in all patients of acute organophosphorus poisoning, and depending upon these changes and other clinical and biochemical parameters, the patients should immediately be shifted to well equipped ICU for better care which will reduce the mortality rate caused by these highly lethal poisons.

New experimental Oximes in the management of organophosphorus pesticides poisoning

Organophosphorus compounds (OPCs) are widely used in agriculture as pesticides and occasionally in industrial settings. They have also been developed as warfare nerve agents. OPCs poisoning from intentional, accidental, and occupational exposure is a major public health problem, especially across the rural developing world. The main toxic mechanism of OPCs is the inhibition of the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), resulting in accumulation of acetylcholine (ACh) at the synapse with cholinergic crisis and possible death. Exposure to even small amounts of an OPC can be fatal and death is usually caused by respiratory failure. Standard treatment involves the administration of intravenous atropine and an oxime to counteract acetylcholinesterase inhibition at the synapse, but the usefulness of oximes is still debated. During more than five decades, pyridinium oximes have been developed as therapeutic agents used in the medical treatment of poisoning with OPCs. They act by reactivation of AChE inhibited by OPCs. However, their activity in poisonings with pesticides and warfare nerve agents is different, and there is still no universal oxime sufficiently effective against all known OPCs. The aim of this article was to review the most recent findings in this field and compare the protection conferred by the new K-oximes and sugar oximes with the effect of the four recommended pyridinium oximes (pralidoxime, obidoxime, trimedoxime, and HI-6), in the search for a broad-spectrum AChE reactivator.

Effectiveness of fresh frozen plasma as supplementary treatment in organophosphate poisoning

With the establishment of the inadequate efficiency of atropines and oximes in reducing morbidity and mortality of patients poisoned by organophosphates, more attention is given to using other methods such as Fresh Frozen Plasma (FFP) as a bioscavenger to mop up organophosphate toxins. This randomized clinical trial was conducted on 56 organophosphate poisoned patients who were randomly assigned to the FFP and control groups in order of admission. The routine treatment in both groups included atropine and, in moderate to severe cases of poisoning, pralidoxime. The FFP group received four packs of FFP as stat dose at the beginning of treatment. No significant difference was seen between the two groups on the atropine and pralidoxime dosage, hospitalization length and mortality. The present study showed that using four packs of FFP as stat dose at the onset of treatment had no significant effect on the clinical course of organophosphate poisoned patients.