Acute Organophosphate Research Articles

HI-6-Loaded Vehicle of Liposomes Mediated by an Amphiphilic Pillar[5]arene against Paraoxon Poisoning.

Organophosphate (OP) intoxication has become a severe common health matter all over the world. For the treatment of acute OP poisoning, the effective intracerebral delivery of acetylcholinesterase reactivators is crucial. Here, an amphiphilic hydrazide-pillar[5]arene (HP5A-6C), which could be readily integrated into liposomal bilayers' zwitterionic disaturated phosphatidylcholine (DSPC), was synthesized. A T7 peptide-containing guest (G) was attached on the surface via a noncovalent interaction to make mixed liposomes a particularly appealing candidate for brain-targeting delivery. Such coassembly could remain stable at room temperature for up to 6 weeks, and safety evaluations initially verified its fine biological compatibility. The hydrophilic interiors of T7/HP5A-6C@DSPC could further load HI-6 with 89.70% encapsulation efficiency. Support for brain-targeting potency came from imaging results. Notably, intravenous injection of HI-6-loaded vesicles exhibited a remarkable therapeutic effect on paraoxon (POX)-poisoned mice, effectively alleviating seizures and brain damage and significantly increasing the improving survival rate to 60% over the course of 7 days.

Isolated Hypoglossal Nerve Palsy: A Rare Complication of Organophosphate Poisoning

Abstract Purpose: This case report aims to describe a rare manifestation of isolated hypoglossal nerve palsy (HNP) resulting from organophosphate poisoning (OP), specifically organophosphate- induced delayed neuropathy (OPIDN). The primary objective of this case report is to highlight this unusual manifestation and discuss its potential underlying mechanisms, emphasizing the importance of timely diagnosis and appropriate management. Case Report: A 31-year-old male with a history of consuming a commercial chlorpyrifos formulation presented with acute organophosphate poisoning symptoms that improved with appropriate treatment. However, two weeks later, the patient developed neurological deficits (numbness and weakness spreading from the plantar region to the upper limbs) involving the hypoglossal nerve, manifesting as left-sided tongue deviation, fasciculation, and atrophy, resulting in speech and swallowing difficulties. A comprehensive workup ruled out other potential causes of HNP, supporting the link between OPIDN and isolated HNP. Despite regaining limb strength, the patient’s speech and swallowing issues persisted, prompting a follow-up visit to our hospital for further management and rehabilitation. Conclusion: This case report highlights a unique manifestation of OPIDN, resulting in isolated HNP, a rare phenomenon. The correlation between exposure to chlorpyrifos, acute organophosphate poisoning, and delayed onset of HNP suggests a causative relationship. Prompt diagnosis, appropriate treatment, and timely speech and swallowing rehabilitation are vital for optimizing outcomes in such cases. Further research is needed to understand the mechanisms underlying this selective vulnerability of OPIDN and to develop targeted interventions.

Validity of different scoring systems in prediction of intensive care unit admission and mortality in acute organophosphate poisoning.

Organophosphate compounds (OPCs) pose significant health risks, especially in developing countries with limited resources. Predicting outcomes in OPCs poisoning is crucial for guiding clinical management and reducing mortality rates. The aim of this study to evaluate the validity of different scoring systems Rapid Emergency Medicine Score, Multiple Organ Dysfunction Score, Acute Physiology and Chronic Health Evaluation Score, and Poison Severity Score in prediction of intensive care unit (ICU) admission and mortality of acute OPCs poisoning patients. A cross-sectional study was conducted on 103 patients admitted to Xx Poison Control Center between May 2022 and June 2023. Scoring systems were applied at admission, and their performance in predicting the need for ICU admission and mortality was evaluated using receiver operating characteristic (ROC) curve analysis. Most patients survived (92.2%). Only 13.6% of the patients required ICU admission. Significant differences in median scores were observed between survivors and non-survivors and between patients requiring ICU admission and those who did not. Multiple Organ Dysfunction Score exhibited the highest discriminatory power for predicting both ICU admission (AUC=0.983) and mortality (AUC=0.999). The findings highlight the importance of utilizing scoring systems, particularly Multiple organ dysfunction score, for prediction of poor outcomes of acute OPCs poisoning.

Life-Saving Resin: Hemoperfusion's Role in Overcoming Acute Organophosphate and Carbamate Poisoning

Background: Acute poisoning from organophosphates and carbamates is a major public health concern. These poisons inhibit acetylcholinesterase, leading to severe clinical manifestations. Traditional treatments, such as atropine and oximes, often fall short in severe cases, necessitating alternative therapeutic approaches. Hemoperfusion, an extracorporeal blood purification technique, has shown promise in improving outcomes for poisoning cases. This study aimed to estimate the clinical outcomes of resin-based HOD in individuals with acute organophosphate and carbamate poisoning admitted to a South Asian tertiary care hospital. Methods: A prospective observational study was carried out involving 50 patients diagnosed with acute organophosphate (n=30) or carbamate (n=20) poisoning. Patients underwent standard treatment protocols, and eligible individuals received resin-based hemoperfusion. Data on demographic details, clinical outcomes, complications, and biochemical parameters were collected and analysed using SPSS version 25.0. Results: The study found an overall recovery rate of 84%, with 80% recovery in the organophosphate group and 90% in the carbamate group. The complication rate was 12%, and the mortality rate was 4%. Cholinesterase levels significantly increased post-hemoperfusion, with a mean rise of 600 U/L. Time to treatment was a significant predictor of positive outcomes (p=0.011). Conclusion: Resin-based hemoperfusion is effective in treating acute organophosphate and carbamate poisoning, significantly improving recovery rates and reducing mortality. Early intervention is crucial for optimal outcomes. This treatment modality should be considered a valuable component of poisoning management protocols, especially in resource-limited settings. Recommendations: Further research with larger sample sizes and randomized controlled trials is recommended to confirm these findings and explore additional factors influencing treatment outcomes. Implementation of resin-based hemoperfusion in standard treatment protocols for severe poisoning cases is advised to enhance patient care and survival rates. Keywords: Organophosphate poisoning, Carbamate poisoning, Hemoperfusion, Clinical outcomes

Quantification of 11 metabolites in rat urine after exposure to organophosphates

BackgroundThe aim of the study was to develop a technique for quantitative determination of rat urine metabolites by HPLC–MS/MS, which can be used to search for biomarkers of acute intoxication with organophosphates (OPs).ResultsThe content of metabolites in the urine of rats exposed to a single dose of paraoxon (POX1x); interval, twice daily administration of paraoxon (POX2x); exposure to 2-(o-cresyl)-4H-1, 3, 2-benzodioxaphosphorin-2-oxide and paraoxon (CBPOX) was investigated. New data were obtained on the content in the urine of intact rats as well as rats in 3 models of OP poisoning: 3-methylhistidine, threonine, creatine, creatinine, lactic acid, acetylcarnitine, inosine, hypoxanthine, adenine, 3-hydroxymethyl-butyrate and 2-hydroxymethyl-butyrate.ConclusionsThe proposed assay procedure is a simple and reliable tool for urine metabolomic studies. Within 1–3 days after OP exposure in all three models of acute intoxication, the concentration of metabolites in rat urine, with the exception of adenine, changes similarly and symmetrically, regardless of the method of poisoning modeling, in all three models of acute intoxication. Further studies are needed to determine the specificity and reliability of using urinary metabolite concentration changes as potential biomarkers of acute organophosphate intoxication.Graphical

A Study on the Clinical Profile of Cholinergic Insecticide Poisoning in a Tertiary Care Centre in Kerala

Introduction In India, insecticides pose a significant risk of poisoning, particularly in rural households where they are readily accessible and frequently employed for deliberate self-harm. Acute organophosphate (OP) poisoning represents a critical medical emergency and stands as a significant contributor to both mortality and morbidity rates. Among the various insecticides, OP poisoning stands out as the most commonly encountered. Patients afflicted with OP poisoning may experience respiratory failure due to several factors, including the aspiration of gastric contents, excessive secretions, pneumonia, and septicemia, which can further escalate into acute respiratory distress syndrome1 . Objectives To determine the clinical profile of cholinergic insecticide poisoning at the Government Medical College, Alappuzha, in both medical wards and the ICU.

Acute intoxication with diisopropylfluorophosphate promotes cellular senescence in the adult male rat brain.

Acute intoxication with high levels of organophosphate (OP) cholinesterase inhibitors can cause cholinergic crisis, which is associated with acute, life-threatening parasympathomimetic symptoms, respiratory depression and seizures that can rapidly progress to status epilepticus (SE). Clinical and experimental data demonstrate that individuals who survive these acute neurotoxic effects often develop significant chronic morbidity, including behavioral deficits. The pathogenic mechanism(s) that link acute OP intoxication to chronic neurological deficits remain speculative. Cellular senescence has been linked to behavioral deficits associated with aging and neurodegenerative disease, but whether acute OP intoxication triggers cellular senescence in the brain has not been investigated. Here, we test this hypothesis in a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague-Dawley rats were administered DFP (4mg/kg, s.c.). Control animals were administered an equal volume (300µL) of sterile phosphate-buffered saline (s.c.). Both groups were subsequently injected with atropine sulfate (2mg/kg, i.m.) and 2-pralidoxime (25mg/kg, i.m.). DFP triggered seizure activity within minutes that rapidly progressed to SE, as determined using behavioral seizure criteria. Brains were collected from animals at 1, 3, and 6months post-exposure for immunohistochemical analyses of p16, a biomarker of cellular senescence. While there was no immunohistochemical evidence of cellular senescence at 1-month post-exposure, at 3- and 6-months post-exposure, p16 immunoreactivity was significantly increased in the CA3 and dentate gyrus of the hippocampus, amygdala, piriform cortex and thalamus, but not the CA1 region of the hippocampus or the somatosensory cortex. Co-localization of p16 immunoreactivity with cell-specific biomarkers, specifically, NeuN, GFAP, S100β, IBA1 and CD31, revealed that p16 expression in the brain of DFP animals is neuron-specific. The spatial distribution of p16-immunopositive cells overlapped with expression of senescence associated β-galactosidase and with degenerating neurons identified by FluoroJade-C (FJC) staining. The co-occurrence of p16 and FJC was positively correlated. This study implicates cellular senescence as a novel pathogenic mechanism underlying the chronic neurological deficits observed in individuals who survive OP-induced cholinergic crisis.

Quantitative T2 mapping-based longitudinal assessment of brain injury and therapeutic rescue in the rat following acute organophosphate intoxication

Acute intoxication with organophosphate (OP) cholinesterase inhibitors poses a significant public health risk. While currently approved medical countermeasures can improve survival rates, they often fail to prevent chronic neurological damage. Therefore, there is need to develop effective therapies and quantitative metrics for assessing OP-induced brain injury and its rescue by these therapies. In this study we used a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP), to test the hypothesis that T2 measures obtained from brain magnetic resonance imaging (MRI) scans provide quantitative metrics of brain injury and therapeutic efficacy. Adult male Sprague Dawley rats were imaged on a 7T MRI scanner at 3, 7 and 28 days post-exposure to DFP or vehicle (VEH) with or without treatment with the standard of care antiseizure drug, midazolam (MDZ); a novel antiseizure medication, allopregnanolone (ALLO); or combination therapy with MDZ and ALLO (DUO). Our results show that mean T2 values in DFP-exposed animals were: (1) higher than VEH in all volumes of interest (VOIs) at day 3; (2) decreased with time; and (3) decreased in the thalamus at day 28. Treatment with ALLO or DUO, but not MDZ alone, significantly decreased mean T2 values relative to untreated DFP animals in the piriform cortex at day 3. On day 28, the DUO group showed the most favorable T2 characteristics. This study supports the utility of T2 mapping for longitudinally monitoring brain injury and highlights the therapeutic potential of ALLO as an adjunct therapy to mitigate chronic morbidity associated with acute OP intoxication.

Cardiovascular responses of adult male Sprague–Dawley rats following acute organophosphate intoxication and post-exposure treatment with midazolam with or without allopregnanolone

Recent experimental evidence suggests combined treatment with midazolam and allopregnanolone is more effective than midazolam alone in terminating seizures triggered by acute organophosphate (OP) intoxication. However, there are concerns that combined midazolam and allopregnanolone increases risk of adverse cardiovascular events. To address this, we used telemetry devices to record cardiovascular responses in adult male Sprague–Dawley rats acutely intoxicated with diisopropylfluorophosphate (DFP). Animals were administered DFP (4 mg/kg, sc), followed immediately by atropine (2 mg/kg, i.m.) and 2-PAM (25 mg/kg, i.m.). At 40 min post-exposure, a subset of animals received midazolam (0.65 mg/kg, im); at 50 min, these rats received a second dose of midazolam or allopregnanolone (12 mg/kg, im). DFP significantly increased blood pressure by ~ 80 mmHg and pulse pressure by ~ 34 mmHg that peaked within 12 min. DFP also increased core temperature by ~ 3.5 °C and heart rate by ~ 250 bpm that peaked at ~ 2 h. Heart rate variability (HRV), an index of autonomic function, was reduced by ~ 80%. All acute (within 15 min of exposure) and two-thirds of delayed (hours after exposure) mortalities were associated with non-ventricular cardiac events within 10 min of cardiovascular collapse, suggesting that non-ventricular events should be closely monitored in OP-poisoned patients. Compared to rats that survived DFP intoxication without treatment, midazolam significantly improved recovery of cardiovascular parameters and HRV, an effect enhanced by allopregnanolone. These data demonstrate that midazolam improved recovery of cardiovascular and autonomic function and that the combination of midazolam and allopregnanolone may be a better therapeutic strategy than midazolam alone.

Comparative Analysis of Outcomes in Acute Organophosphate Poisoning With and Without N-acetyl Cysteine Intervention.

Organophosphorus poisoning (OPP) stands as a significant health concern in numerous regions, especially in developing nations. Despite the rising complexities and case fatalities associated with exposure, the treatment approach has remained unchanged for many years. Based on clinical insights, certain pharmacologic agents have demonstrated utility in enhancing outcomes and reducing complications arising from this type of exposure. The objective of this study is to compare the outcome of N-acetyl cysteine in the treatment of acute organophosphate poisoning cases. In terms of a) its impact on the requirement of atropine, b) Length of hospital stay, and mortality. The study was conducted in the intensive care unit (ICU) of the General Hospital Lahore. Thirty patients with a history and clinical presentation indicative of acute organophosphorus poisoning were randomly divided into two groups in a 1:1 ratio. The treatment group received parenteral administration of atropine, pralidoxime, and N-acetylcysteine (NAC) as an adjuvant, and the control group received standard treatment for acute organophosphate (OP) toxicity. Throughout the study duration, 30 patients suffering acute organophosphate (OP) toxicity (14 men, 16 women) were examined, with an age mean of (25.83±11.59) years. In the interventional group, only four patients required ICU admission, but in the control group, eight patients were admitted to ICU. The correlation result between the dose of atropine and length of hospital stays was not statistically significant between both study groups (<0.005). Plasma Cholinesterase (PChE) level (KU L-1) and total dose of Pralidoxime (g) were statistically significant in the length of hospital stay. The data was not normally distributed, so the non-parametric tests were applied. The Wilcoxon ranked test showed significant improvement in both the controlled and interventional groups because the p-value was (<0.005). Intergroup comparison analyzed by using the Mann-Whitney U test showed a significant reduction in the severity and other associated symptoms in the interventional group because the p-value was (0.001). The outcome demonstrated that the NAC group had a decreased demand for atropine rather than Pralidoxime. In the NAC group, the length of hospital stay and mortality was decreased. The administration of NAC to the present study procedure for acute organophosphate (OP) poisoning is suggested.

Acute Poisoning Emergencies at Gulu University Teaching Hospitals in Northern Uganda: Prevalence, Outcomes and Clinical Challenges

Acute poisonings, including envenomation as well as toxicological emergencies stemming from accidental or intentional ingestion of poisonous substances or drug overdose, are significant worldwide causes of morbidity and mortality. The study aimed to characterise acute poisoning emergencies admitted to two major hospitals in Northern Uganda. We conducted a retrospective review of charts of all patients admitted with acute poisoning emergencies between January and December 2021, as well as a structured interview of hospital staff working in these hospitals on challenges faced while managing these emergencies. Of the total 40,653 patient admissions, 416 (1%) were due to acute poisonings. The majority were admitted to SMHL (71.4%), 43.3% were between 20 and 40 years of age, and 59.9% were males. The average length of hospital stay was 1 (0-3). The most frequent diagnoses were acute alcohol intoxications (27.2%, n=113), snake bites (26.0%, n=108), and organophosphate poisonings (21.2%, n=88). Only 29.6% (n=123) of patients received antidotes. Peak admissions were observed in February, May, and July. The majority of poisonings were intentional (61.3%), resulting in a Case Fatality Rate of 6.3%. In the qualitative findings, participants highlighted key challenges in managing these conditions, including the lack of antidotes, patients presenting late at the hospital, economic barriers, staff shortages, and limited community awareness. Acute poisoning, especially acute alcoholic intoxication, snake bites and organophosphate poisoning, are common in northern Uganda, with significant numbers dying from it. The lack of antidotes remains a problem in these hospitals. Restriction of alcohol consumption use of agricultural organophosphates, and training of healthcare workers in managing these emergencies are recommended

Prevalence and management outcomes of organophosphorus poisoning in emergency departments: systematic review

Organophosphorus poisoning (OPP) is a significant public health concern in various regions, with its prevalence and outcomes influenced by diverse sociodemographic factors. This systematic review aimed to collate and analyze data from multiple studies to provide a comprehensive understanding of the prevalence, risk factors, and management outcomes of OPP in emergency departments. A systematic search was conducted in October 2023, adhering to the PRISMA guidelines, primarily using PubMed. Studies were selected based on specific inclusion and exclusion criteria, with a focus on those that investigated OPP prevalence and management outcomes in emergency departments. Out of 87 initial studies, 9 met the inclusion criteria, encompassing a total of 1,469 participants from countries like Nepal, India, Korea, China, and Turkey. The studies predominantly included the younger to middle-aged demographic, with a significant male representation indicating that young males. Key findings highlighted the role of pesticides, especially organophosphorus compounds, in intentional poisonings, which can be seen more in young and unmarried females. Additionally, the therapeutic efficacy of treatments like plasma exchange has proven to be another promising tool for management. Finally, the importance of specific prognostic indicators such as D-CRP and the sequential organ failure assessment (SOFA) score, when combined with lactate levels (SOFA-Lac), are superior predictors of mortality in patients with acute organophosphate pesticide poisoning. The insights from this review emphasize the need for targeted interventions, both therapeutic and preventive, to address the challenges posed by OPP, especially in high-risk populations.

Neuroprotectant Activity of Novel Water-Soluble Synthetic Neurosteroids on Organophosphate Intoxication and Status Epilepticus-Induced Long-Term Neurological Dysfunction, Neurodegeneration, and Neuroinflammation.

Organophosphates (OPs) and nerve agents are potent neurotoxic compounds that cause seizures, status epilepticus (SE), brain injury, or death. There are persistent long-term neurologic and neurodegenerative effects that manifest months to years after the initial exposure. Current antidotes are ineffective in preventing these long-term neurobehavioral and neuropathological changes. Additionally, there are few effective neuroprotectants for mitigating the long-term effects of acute OP intoxication. We have pioneered neurosteroids as novel anticonvulsants and neuroprotectants for OP intoxication and seizures. In this study, we evaluated the efficacy of two novel synthetic, water-soluble neurosteroids, valaxanolone (VX) and lysaxanolone (LX), in combating the long-term behavioral and neuropathological impairments caused by acute OP intoxication and SE. Animals were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP) and were treated with VX or LX in addition to midazolam at 40 minutes postexposure. The extent of neurodegeneration, along with various behavioral and memory deficits, were assessed at 3 months postexposure. VX significantly reduced deficits of aggressive behavior, anxiety, memory, and depressive-like traits in control (DFP-exposed, midazolam-treated) animals; VX also significantly prevented the DFP-induced chronic loss of NeuN(+) principal neurons and PV(+) inhibitory neurons in the hippocampus and other regions. Additionally, VX-treated animals exhibited a reduced inflammatory response with decreased GFAP(+) astrogliosis and IBA1(+) microgliosis in the hippocampus, amygdala, and other regions. Similarly, LX showed significant improvement in behavioral and memory deficits, and reduced neurodegeneration and cellular neuroinflammation. Together, these results demonstrate the neuroprotectant effects of the novel synthetic neurosteroids in mitigating the long-term neurologic dysfunction and neurodegeneration associated with OP exposure. SIGNIFICANCE STATEMENT: Survivors of nerve agents and organophosphate (OP) exposures suffer from long-term neurological deficits. Currently, there is no specific drug therapy for mitigating the impact of OP exposure. However, novel synthetic neurosteroids that activate tonic inhibition provide a viable option for treating OP intoxication. The data from this study indicates the neuroprotective effects of synthetic, water-soluble neurosteroids for attenuation of long-term neurological deficits after OP intoxication. These findings establish valaxanolone and lysaxanolone as potent and efficacious neuroprotectants suitable for injectable dosing.

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.

Long-Term Neuropsychiatric Developmental Defects after Neonatal Organophosphate Exposure: Mitigation by Synthetic Neurosteroids.

Children are much more susceptible to the neurotoxic effects of organophosphate (OP) pesticides and nerve agents than adults. OP poisoning in children leads to acute seizures and neuropsychiatric sequela, including the development of long-term disabilities and cognitive impairments. Despite these risks, there are few chronic rodent models that use pediatric OP exposure for studying neurodevelopmental consequences and interventions. Here, we investigated the protective effect of the neurosteroid ganaxolone (GX) on the long-term developmental impact of neonatal exposure to the OP compound, diisopropyl-fluorophosphate (DFP). Pediatric postnatal day-28 rats were acutely exposed to DFP, and at 3 and 10 months after exposure, they were evaluated using a series of cognitive and behavioral tests with or without the postexposure treatment of GX. Analysis of the neuropathology was performed after 10 months. DFP-exposed animals displayed significant long-term deficits in mood, anxiety, depression, and aggressive traits. In spatial and nonspatial cognitive tests, they displayed striking impairments in learning and memory. Analysis of brain sections showed significant loss of neuronal nuclei antigen(+) principal neurons, parvalbumin(+) inhibitory interneurons, and neurogenesis, along with increased astrogliosis, microglial neuroinflammation, and mossy fiber sprouting. These detrimental neuropathological changes are consistent with behavioral dysfunctions. In the neurosteroid GX-treated cohort, behavioral and cognitive deficits were significantly reduced and were associated with strong protection against long-term neuroinflammation and neurodegeneration. In conclusion, this pediatric model replicates the salient features of children exposed to OPs, and the protective outcomes from neurosteroid intervention support the viability of developing this strategy for mitigating the long-term effects of acute OP exposure in children. SIGNIFICANCE STATEMENT: An estimated 3 million organophosphate exposures occur annually worldwide, with children comprising over 30% of all victims. Our understanding of the neurodevelopmental consequences in children exposed to organophosphates is limited. Here, we investigated the long-term impact of neonatal exposure to diisopropyl-fluorophosphate in pediatric rats. Neurosteroid treatment protected against major deficits in behavior and memory and was well correlated with neuropathological changes. Overall, this pediatric model is helpful to screen novel therapies to mitigate long-term developmental deficits of organophosphate exposure.

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.

Time- and region-dependent blood-brain barrier impairment in a rat model of organophosphate-induced status epilepticus

Acute organophosphate (OP) intoxication can trigger seizures that progress to status epilepticus (SE), and survivors often develop chronic morbidities, including spontaneous recurrent seizures (SRS). The pathogenic mechanisms underlying OP-induced SRS are unknown, but increased BBB permeability is hypothesized to be involved. Previous studies reported BBB leakage following OP-induced SE, but key information regarding time and regional distribution of BBB impairment during the epileptogenic period is missing. To address this data gap, we characterized the spatiotemporal progression of BBB impairment during the first week post-exposure in a rat model of diisopropylfluorophosphate-induced SE, using MRI and albumin immunohistochemistry. Increased BBB permeability, which was detected at 6 h and persisted up to 7 d post-exposure, was most severe and persistent in the piriform cortex and amygdala, moderate but persistent in the thalamus, and less severe and transient in the hippocampus and somatosensory cortex. The extent of BBB leakage was positively correlated with behavioral seizure severity, with the strongest association identified in the piriform cortex and amygdala. These findings provide evidence of the duration, magnitude and spatial breakdown of the BBB during the epileptogenic period following OP-induced SE and support BBB regulation as a viable therapeutic target for preventing SRS following acute OP intoxication.

A study of white blood cell counts as a prognostic marker among patients sustaining organophosphate poisoning presenting to the Emergency Department of a Tertiary Care Hospital

Abstract Background: Organophosphate (OP) pesticide poisoning is a primary concern in rural regions of developing nations, posing a significant clinical challenge. The mortality rate from acute OP compound poisoning surpasses any other harmful substance. In the case of stressful events like injuries and poisoning, the observed leucocytosis and neutrophilia can be attributed to neutrophil margination rather than an increase in bone marrow production. Materials and Methods: Between June 2020 and September 2021, a prospective observational study was conducted at a tertiary care institute in Tamil Nadu. The study included 50 patients admitted to the Institute’s Medical Emergency Ward with suspected Organophosphorus poisoning. These patients were categorized into three grades, mild, moderate, and severe, using Dresbach’s classification based on the severity of their manifestations. Results: Among the 50 cases studied, 29 were females, and 21 were males. The predominant agent is responsible for organophosphate (OP) poisoning was chlorpyrifos, affecting 37 patients. Most cases (78%) presented with mild manifestations, 12% presented with moderate presentations, and 10% had severe manifestations. Most (72%) of patients sought medical attention within 4 h of consumption (n = 36). Conclusion: While insufficient to confirm or rule out severe poisoning, leukocyte counts hold some moderate capacity to differentiate between patients with and without significant poisoning. As a result, these counts could have a meaningful impact on decisions regarding patient disposition.

Organophospate-Induced Pathology: Mechanisms of Development, Principles of Therapy and Features of Experimental Studies

Organophosphates (OP) are one of the most common neurotoxic xenobiotics. In acute OP poisoning, as a result of suppression of synaptic acetylcholinesterase (AChE) activity, a cholinergic syndrome develops, which can transform into status epilepticus. Within a few days after acute poisoning, the so-called an intermediate syndrome can develop, which is associated with prolonged inhibition of AChE, desensitization of nicotinic receptors, and functional degradation of synapses and muscle fibers. In 10–20 days after a single acute or repeated subacute poisoning, OP-induced delayed polyneuropathy (OPIDN) can develop – a neurodegenerative disease, the signs of which are ataxia, loss of function of the distal sensory and motor axons of peripheral nerves. The occurrence of a neuropsychiatric disorder (NPD) caused by chronic exposure to relatively low-toxicity organophosphorus compounds is usually not associated with acute poisoning; symptoms include cognitive impairment, chronic fatigue, and extrapyramidal symptoms. The list of possible diseases or pathological conditions (syndromes) that develop as a result of acute, subacute or chronic effects of OP on the human body has expanded in recent years due a number of known neurodegenerative diseases (Alzheimer’s, Parkinson’s, multiple sclerosis, etc.). The aging of the body in general and the aging of the brain in particular are considered in the review from the point of view of the consequences of OP poisoning, which can serve as a nonspecific trigger of aging and related neurodegenerative diseases. Gulf syndrome is not a consequence of OP intoxication, but is also of interest and is considered in the context of OP-induced pathology, since its etiology and pathogenesis are associated with the exposure to cholinesterase inhibitors. The review presents data indicating the important role of the vascular endothelium in the development of OP-induced pathology; The first suggestions were made by clinicians in the late 1980s, and the first experimental data were obtained in the early 2000s. The principles of therapy for acute poisoning are outlined, taking into account experimental data from recent years. Some methods for studying OP in experiments in vitro, ex vivo and in vivo with laboratory animals, including the use of carboxylesterase inhibitors, are presented. The most important part of in vivo investigations has been and remains the search for new biomarkers to assess the effectiveness of adjuvant and regenerative therapies.

Acute exposure to chlorpyrifos differentially impacts survival and cardiovascular function of 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 these evidence, no studies have contrasted the cardiovascular (CV) effects of OP poisoning under conditions of normotension and hypertension. We hypothesized that hypertensive rats would have a greater impairment of CV function after acute exposure to chlorpyrifos (CPF), an OP compound. 12-14 week-old male normotensive Wistar and Spontaneously Hypertensive rats (SHRs) were intraperitoneally (i.p.) injected with saline (NaCl 0.9%) or 20 mg.kg-1 of CPF, a previously shown sublethal dose in normotensive rats. 24-hour survival was recorded and through cannulation of the femoral artery and vein, we assessed blood pressure (BP) and heart rate (HR) recordings and chemically activated the Bezold-Jarisch Reflex (BJR), the Chemoreflex (CR), as well as assessed the cardiac autonomic tone (AUT). BJR was activated by phenylbiguanide (PBG; 1.5; 3; 6; 12; 24 μg/kg; i.v.) and the CR by potassium cyanide (KCN, 10, 20, 40 and 80 μg/ rat; i.v.) injections, while the AUT was assessed by pharmacological blockade with atenolol (4mg.kg-1, i.v) and atropine (2mg.kg-1, i.v). CPF acute exposure induced 33% mortality in SHR without leading to lethality in Wistar rats. CPF poisoning impaired the BJR hypotensive response in Wistar rats for all PBG doses tested (ΔDBP: - 33.83±4.88 vs. -14.16±2.68; -44.58±3.48 vs. -30.58±2.16; -66.16±2.50 vs. -36.16±2.54; -72.66±2.66 vs. -47.91±2.50; -78.66±2.35 vs.-61.58±2.40; p&lt;0.05 Wistar saline vs Wistar CPF) and the bradycardic response at the dose of 6 and 12μg/kg, respectively (ΔHR: -268.66±14.77 vs. -216.66±11.11; -304.58±13.42 vs. -241.66±11.01; p&lt;0.05 Wistar saline vs Wistar CPF), without affecting the SHR strain. No CPF-induced changes were observed for the CR and AUT between strains. Our findings show that, despite being sublethal in normotensive rats, CPF lead to mortality in hypertensive rats. However, contrary to our hypothesis, CPF poisoning did not further impaired CV function in SHR, but significantly worsen BJR function in Wistar rats. Despite not producing greater impairment in CV function, CPF poisoning leads to greater mortality under hypertension, which may impose a significant risk in individuals with this comorbidity. Aitken AV, was recipeint of Fapes Foundation scholarship. Minassa VS, Batista TJ were recipients of Capes Foundation scholarship. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.