Acute Organophosphate Research Articles

Acute pancreatitis, a significant mortality predictor in acute organophosphate poisoning: an observational study in a tertiary care centre in north India

Background: Organophosphate compounds are one of the most common agents used as poison and acts by accumulation of acetylcholine hormone at neuronal synapses resulting in the symptoms like excessive salivation, vomiting, urination, and increased serum amylase and lipase levels. APACHE 2 score along with ultrasound modality can be used to assess the acute pancreatitis. The primary aim of the study is to find correlation of serum amylase and lipase levels with duration of ICU stay and with radio-logical variables like bulky pancreas. Methods: This observational study conducted at GSVM medical college, Kanpur from December 2020 to October 2022 included 58 out of total 94 admitted patients with acute organophosphate intoxicationn on the basis of inclusion and exclusion criteria. Patients were divided in 3 groups as mild, moderate and severe using q SOFA score at the time of admission. Results: Acute organophosphate poisoning was more prevalent among 20-40 years of age group. Mean serum amylase level values in q SOFA category 0, 1, 2, 3 were 65.2, 82.0, 118.4, 329.9 IU/l respectively and that of mean serum lipase levels on day 1 of admission values were 42.0, 44.3, 38.6 and 115.5 IU/l respectively. Serum amylase levels were positively correlated with duration of ICU stay and were better predictor for acute pancreatitis. Conclusions: In this study we concluded that serum amylase is a better predictor of duration of ICU stay and acute pancreatitis in patients admitted with acute organophosphate poisoning.

The role of a combination of N-acetylcysteine and magnesium sulfate as adjuvants to standard therapy in acute organophosphate poisoning: A randomized controlled trial

BackgroundMortality in acute organophosphate (OP) poisoning remains high despite current standard therapy with atropine and oximes. Due to dose-limiting side effects of atropine, novel therapies are targeting other putative mechanisms of injury, including oxidative damage, to reduce atropine dosage. ObjectivesN-acetylcysteine (NAC) and magnesium sulfate (MgSO4) have different mechanisms of actions and should act synergistically in OP poisoning. In this study, we wanted to evaluate whether this novel combination, used as an adjuvant to standard care, could improve clinical outcomes. MethodsThe study was conducted in the Emergency Department and ICU of AIIMS Bhubaneswar (a tertiary care center and government teaching institute) between July 2019 and July 2021. Eighty-eight adult patients with history and clinical features of acute OP poisoning were randomly allocated (1:1) into two groups. The Study group received 600 mg NAC via nasogastric tube thrice daily for 3 days plus a single dose of 4 g Inj. MgSO4 IV on first day and the Control group received suitably matched placebo (double-blinding) – in addition to standard care in both the groups. The primary outcome measure was to compare the total dose of Inj. Atropine required (cumulative over the entire treatment duration) between the control group and the study group receiving NAC and MgSO4. The secondary outcome measures were lengths of ICU and hospital stays, need and duration of mechanical ventilation, the differences in BuChE activity, oxidative stress biomarkers – MDA and GSH levels, the incidences of adverse effects including delayed sequalae like intermediate syndrome and OPIDN, and comparison of mortality between the two groups. ResultsData from 43 patients in Control and 42 patients in Study group was finally analyzed. The baseline parameters were comparable. Total atropine requirements were lower in the Study group [175.33 ± 81.25 mg (150.01–200.65)] compared to the Control [210.63 ± 102.29 mg (179.15–242.11)] [Mean ± SD (95% CI)], but was not statistically significant. No significant differences in any of the other clinical or biochemical parameters were noted. ConclusionThe N-acetylcysteine and MgSO4 combination as adjuvants failed to significantly reduce atropine requirements, ICU/hospital stay, mechanical ventilatory requirements, mortality and did not offer protection against oxidative damage.

ChatGPT in Clinical Toxicology.

ChatGPT has recently been shown to pass the United States Medical Licensing Examination (USMLE). We tested ChatGPT (Feb 13, 2023 release) using a typical clinical toxicology case of acute organophosphate poisoning. ChatGPT fared well in answering all of our queries regarding it.

STUDY OF SERUM AMYLASE LEVELS IN ORGANOPHOSPHATE POISONING

Organophosphate (OP) insecticides are the most probable common cause of acute poisonings in developing countries. OP intoxication often presents as medical emergencies, and its related morbidity and mortality have not decreased despite major advances in critical care.This study aims to determine the impact of serum amylase level for estimation of prognosis in patients with acute OP poisoning. Method: This prospective observational hospital-based study was performed on 100 patients with acute OP poisoning. Demographics data, clinical profile, serum amylase levels, complications,hospital stay and outcome were determined.Data were analyzed in the form of a frequency distributions using SPSS 26.0 version software.Result: Most patients were young adults with mean age of 29yrs ± 11yrs with slightly male predominance. Mean serum amylase level was significantly higher among patients with morbidity and mortality. Conclusion: Among patients with OP poisoning,higher serum amylase than normal was associated with severe clinical course and increased risk for mortality.Determination of serum amylase can be an effective marker of the prognosis and clinical course among OP poisoning patients.

Performance of new Poisoning Mortality Score in comparison with SOFA and APACHE II scores in acute organophosphate poisoning

Introduction: Organophosphate (OP) poisoning is a serious public health problem in underdeveloped nations. Many cases of severe poisoning and more than 220,000 deaths are recorded every year. Early detection and treatment can save lives because OP poisoning has a significant fatality rate. The new Poisoning Mortality Score (PMS) has been developed for clinical decision-making and therapeutic guidance in patients with acute poisoning. Methods: This is a retrospective study that included 236 patients with acute OP poisoning who got admitted to a tertiary care hospital over two years after obtaining permission from the institutional ethical committee. The PMS, Sequential Organ Failure Assessment (SOFA), and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were calculated based on patient details. Results: The results showed that the mean age of patients was 32.8 ± 13.4 years; 50.8% were men and 49.2% were women. Out of 236 patients, 214 got discharged and 22 died. The mean ± SD of PMS, SOFA score, and APACHE II scores among the discharged patients were 51±7, 1 ± 2, and 5 ± 5, respectively, and those among the expired patients were 70 ± 12, 7 ± 3, and 28 ± 9, respectively. The best cut-off points for predicting mortality in acute OP poisoning patients for PMS, SOFA score, and APACHE II scores were >65, >3, and >15 with sensitivities of 77.27%, 95.45%, and 95.45%, specificities of 96.26%, 91.59%, and 95.79%, and areas under the receiver operating characteristic curve of 0.917, 0.970, and 0.984, respectively. Conclusion: The study showed that the new PMS is significantly associated with the prediction of mortality in acute OP poisoning in comparison with SOFA and APACHE II scores.

Novel image analysis tool for rapid screening of cell morphology in preclinical animal models of disease

The field of cell biology has seen major advances in both cellular imaging modalities and the development of automated image analysis platforms that increase rigor, reproducibility, and throughput for large imaging data sets. However, there remains a need for tools that provide accurate morphometric analysis of single cells with complex, dynamic cytoarchitecture in a high-throughput and unbiased manner. We developed a fully automated image-analysis algorithm to rapidly detect and quantify changes in cellular morphology using microglia cells, an innate immune cell within the central nervous system, as representative of cells that exhibit dynamic and complex cytoarchitectural changes. We used two preclinical animal models that exhibit robust changes in microglia morphology: (1) a rat model of acute organophosphate intoxication, which was used to generate fluorescently labeled images for algorithm development; and (2) a rat model of traumatic brain injury, which was used to validate the algorithm using cells labeled using chromogenic detection methods. All ex vivo brain sections were immunolabeled for IBA-1 using fluorescence or diaminobenzidine (DAB) labeling, images were acquired using a high content imaging system and analyzed using a custom-built algorithm. The exploratory data set revealed eight statistically significant and quantitative morphometric parameters that distinguished between phenotypically distinct groups of microglia. Manual validation of single-cell morphology was strongly correlated with the automated analysis and was further supported by a comparison with traditional stereology methods. Existing image analysis pipelines rely on high-resolution images of individual cells, which limits sample size and is subject to selection bias. However, our fully automated method integrates quantification of morphology and fluorescent/chromogenic signals in images from multiple brain regions acquired using high-content imaging. In summary, our free, customizable image analysis tool provides a high-throughput, unbiased method for accurately detecting and quantifying morphological changes in cells with complex morphologies.

Prediction of acute organophosphate poisoning severity using machine learning techniques

Poisoning with organophosphate compounds is a significant public health risk, especially in developing countries. Considering the importance of early and accurate prediction of organophosphate poisoning prognosis, the aim of this study was to develop a machine learning-based prediction model to predict the severity of organophosphate poisoning. The data of patients with organophosphate poisoning were retrospectively extracted and split into training and test sets in a ratio of 70:30. The feature selection was done by least absolute shrinkage and selection operator method. Selected features were fed into five machine learning techniques, including Histogram Boosting Gradient, eXtreme Gradient Boosting, K-Nearest Neighborhood, Support Vector Machine (SVM) (kernel = linear), and Random Forest. The Scikit-learn library in Python programming language was used to implement the models. Finally, the performance of developed models was measured using ten-fold cross-validation methods and some evaluation criteria with 95 % confidence intervals. A total of 1237 patients were used to train and test the machine learning models. According to the criteria determining severe organophosphate poisoning, 732 patients were assigned to group 1 (patients with mild to moderate poisoning) and 505 patients were assigned to group 2 (patients with severe poisoning). With an AUC value of 0.907 (95 % CI 0.89–0.92), the model developed using XGBoost outperformed other models. Feature importance evaluation found that venous blood gas-pH, white blood cells, and plasma cholinesterase activity were the top three variables that contribute the most to the prediction performance of the prognosis in patients with organophosphate poisoning. XGBoost model yield an accuracy of 90.1 % (95 % CI 0.891–0.918), specificity of 91.4 % (95 % CI 0.90–0.92), a sensitivity of 89.5 % (95 % CI 0.87–0.91), F-measure of 91.2 % (95 % CI 0.90–0.921), and Kappa statistic of 91.2 % (95 % CI 0.90–0.92). The machine learning-based prediction models can accurately predict the severity of organophosphate poisoning. Based on feature selection techniques, the most important predictors of organophosphate poisoning were VBG-pH, white blood cell count, plasma cholinesterase activity, VBG-BE, and age. The best algorithm with the highest predictive performance was the XGBoost classifier.

ECG CHANGES AS A MANIFESTATION OF CARDIAC COMPLICATIONS OF ORGANO PHOSPHORUS COMPOUND POISIONING

To study the extent, frequency and pathogenesis of the cardiac and electrocardiographical manifestations of acute organophosphate poisoning. 37 adult patients admitted over a three-year period with a diagnosis of acute organophosphate was studied prospectively. The clinical features and electrocardiographical nding were recorded.Cardiac complications developed in 23 patients (62.2 percent). These were: noncardiogenic pulmonary oedema in eight cases (21.6 percent), electrocardiographical abnormalities including prolonged Q-Tc interval in 14 cases (37.8 percent), ST-T changes in 11 cases (29.7 percent), and conduction defects in two cases (5.4 percent). Sinus tachycardia occurred in 15 patients (40.5 percent) and sinus bradycardia in seven patients (18.9 percent). Hypertension developed in ve patients (13.5 percent) and hypotension in four patients (10.8 percent). Five patients (13.5 percent) needed respiratory support because of respiratory depression of which two patients developed intermediate syndrome. Out of 14 patients with prolonged Q-Tc interval, only one had polymorphic ventricular tachycardia of the torsade de pointes type. Two patients died from noncardiogenic pulmonary oedema and one from ventricular brillation, giving a hospital mortality of 8.1 percent.Cardiac complications usually occur during the rst hour after exposure. Hypoxemia, electrolyte derangements and acidosis are major predisposing factors for the development of these complications. Intensive supportive treatment, meticulous respiratory care and administration of atropine in adequate doses very early in the course of the illness will reduce the mortality

Clinical characteristics and early prediction of mortality risk in patients with acute organophosphate poisoning-induced shock.

To further get insights of clinical characteristics of acute organophosphate poisoning-induced shock, investigate the relationship between shock and prognosis, and screen risk indicators for prognosis. A total of 73 patients with acute organophosphate poisoning admitted to our hospital between January 2014 and December 2021 were enrolled in this retrospective study. Patients were divided into the shock group and the non-shock group. The pH value of blood, arterial blood carbon dioxide partial pressure (PaCO2), arterial partial pressure of oxygen (PaO2), base excess (BE), lactic acid (Lac), serum albumin (ALB), total bilirubin (TBIL), alanine aminotransferase (ALT), serum creatinine (Cr), serum potassium (K), serum calcium (Ca), serum sodium (Na), blood chloride (Cl), serum troponin I (cTNI), brain natriuretic peptide (BNP), white blood cell count (WBC), hemoglobin (HGB), platelet count (PLT), and other clinical indicators of patients were recorded. Incidence of shock, time of shock onset, and outcomes of patients were also recorded. Cox proportional hazards regression models were performed for analysis. The incidence of organophosphate poisoning-induced shock was 30.1% (22/73), and 72.7% of shock patients developed shock blood pressure within 6 h. The levels of blood lactate, ALT, Cr, cTNI, BNP, and Cl in the shock group were significantly higher than those in the non-shock group, while the level of Ca and pH value was significantly lower than that in the non-shock group (all p < 0.05). Moreover, compared with patients without shock (2.0%), the mortality rate was significantly increased in patients with shock (36.4%), which was supported by the results from adjusted Cox proportional hazards regression model. We found that shock and elevated serum creatinine were associated with increased risk of death in patients with organophosphate poisoning (shock: HR, 10.9; 95% CI 1.2-96.3; elevated serum creatinine: HR, 1.0, 95% CI 1.0-1.0). This study indicated the association between elevated serum creatinine and increased mortality rates in patients with organophosphate poisoning, highlighting the importance of the comprehensive management of shock, especially the control of renal function, in these poisoning patients.

Pattern and outcome of acute organophosphate poisoning at health facilities of Harari Region, Eastern Ethiopia

Introduction: Pesticides are frequently used by plant cultivars to control pests that could affect yield. Although many local farmers in Eastern Ethiopia use organophosphate insecticides extensively for the production of khat, the pattern and treatment outcome of acute poisoning of these organophosphates has been poorly quantified and reported in this region. Materials and Method: A cross-sectional study design was employed at two public hospitals found in Harari region, Ethiopia. The data were collected through face-to-face interviews and card review, then analyzed with SPSS version 20. Pearson’s Chi-square test was used to compare independent variables with the treatment outcome. Statistical significance is defined at 95% confidence interval of odds ratio not including 1 or p &lt; 0.05. Results: A total of 135 cases of organophosphate were admitted in the emergency departments of the hospitals during the study period. 42.2% of participants were adolescents (age: 11–20 years) while the mean age of all participants was 18.8 ± 12.9 years with a range of 1–61 years. 73.7% of the study participants were rural residents. The result showed that 47.4% of the cases were exposed to the poison accidentally. Family disharmony was the common reason among cases poisoned intentionally. The mean time elapsed between poisoning and reaching the health facility was 3.1 h. Atropine was administered for 47% of the cases. About 11% of cases expired following the poison. The home remedy given, lag time, and residency were found to be factors significantly related to poor treatment outcomes. Conclusion: Easy availability, low cost, and excessive popularity of organophosphate use as pesticides in Eastern Ethiopia have increased the incidence of ingestion, resulting in increasing intentional and unintentional poisoning. In the present study, accidental exposure accounts for 47.4%.

Factors Affecting Nurses' Role Regarding Care of Patients with Acute Organophosphate Poisoning

Factors Affecting Nurses' Role Regarding Care of Patients with Acute Organophosphate Poisoning

Association of Serum Cholinesterase and Liver Enzymes with Clinical Severity and Outcomes in Organophosphorus Poisoning

Abstract Background: Organophosphorus (OP) compound poisoning is a medico-toxic emergency that results in multiorgan failure. The primary mechanism of action is by inhibition of acetylcholinesterase, leading to disruption in processes of oxidative stress, apoptosis, and microsomal metabolism resulting in liver toxicity. The present study was conducted to explore the prognostic value of serum cholinesterase in predicting severity of organophosphorous compound poisoning and the need for ventilatory support; and to understand the role of aspartate aminotransaminase (AST), alanine aminotransaminase (ALT) and bilirubin in assessing the severity of acute organophosphate poisoning. Methodology: Hospital-based prospective observational study was conducted among OP poisoning cases at a tertiary hospital in Hubli. Clinical examination was done during the initial resuscitation and treatment of patients. Three milliliter of plain blood was collected on admission before administration of atropine and plasma cholinesterase level, and other biochemical parameters were estimated. Results: Sixty-five percent of poisoning cases had &gt;50% of cholinesterase activity with normal grade poisoning. Moderate and severe grade poisonings were present among 3% and 5% of poisoning cases, respectively. Patients with cholinesterase level activity of ≤50% had significantly higher proportions of respiratory failure (77%) and fatal outcomes (33%). Median levels of AST (Q2: 73.2 IU/mL) and ALT were significantly higher (Q2: 22.7 IU/L) among severe grade poisoning (Che: &lt;10%) compared to other grades of poisoning. Conclusion: The assessment of cholinesterase level activity in OP poisoning would be a useful guide to the physician for planning of intensive care, duration of hospital stay, and clinical prognosis. Serum AST and ALT levels can also contribute as supportive biomarkers to assess the severity, chances of respiratory failure, and clinical outcomes of OP poisoning.

Succinate prodrugs in combination with atropine and pralidoxime protect cerebral mitochondrial function in a rodent model of acute organophosphate poisoning

Pesticides account for hundreds of millions of cases of acute poisoning worldwide each year, with organophosphates (OPs) being responsible for the majority of all pesticide-related deaths. OPs inhibit the enzyme acetylcholinesterase (AChE), which leads to impairment of the central- and peripheral nervous system. Current standard of care (SOC) alleviates acute neurologic-, cardiovascular- and respiratory symptoms and reduces short term mortality. However, survivors often demonstrate significant neurologic sequelae. This highlights the critical need for further development of adjunctive therapies with novel targets. While the inhibition of AChE is thought to be the main mechanism of injury, mitochondrial dysfunction and resulting metabolic crisis may contribute to the overall toxicity of these agents. We hypothesized that the mitochondrially targeted succinate prodrug NV354 would support mitochondrial function and reduce brain injury during acute intoxication with the OP diisopropylfluorophosphate (DFP). To this end, we developed a rat model of acute DFP intoxication and evaluated the efficacy of NV354 as adjunctive therapy to SOC treatment with atropine and pralidoxime. We demonstrate that NV354, in combination with atropine and pralidoxime therapy, significantly improved cerebral mitochondrial complex IV-linked respiration and reduced signs of brain injury in a rodent model of acute DFP exposure.

The reversed De Ritis ratio for predicting in-hospital mortality among intensive care patients with organophosphate poisoning

Introduction The uncontrolled use of pesticides signifies a substantial health hazard. This study was designed to explore the prognostic role of on-admission hepatic aminotransferases [alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and the reversed De Ritis ratio (ALT/AST)] in the prediction of in-hospital mortality among patients with acute organophosphate (OP) poisoning. Patients and methods We conducted a retrospective study based on extracting the required information from the specific medical records for acutely OP-intoxicated patients admitted to the intensive care unit. Results A total of 49 acutely malathion-intoxicated patients were enrolled in the study. The in-hospital mortality rate was 32.7%. Patients were stratified into survivors and non-survivors. Compared to the survivors, the non-survivors had significantly lower Glasgow coma scale scores, mean arterial blood pressure, significantly higher reversed De Ritis ratio (ALT/AST), and ALT and AST activities. The reversed De Ritis ratio (ALT/AST) and ALT demonstrated good discrimination between the survivors and the non-survivors with an area under the curve (AUC) of 0.708 vs 0.781, respectively, however, AST showed satisfactory discrimination, AUC of 0.694. Conclusion Hepatic aminotransferases are useful in predicting in-hospital mortality in acute OP poisoning. ALT is the most specific biomarker. However, the reversed De Ritis ratio (ALT/AST) is the most sensitive one.

Investigation of acute organophosphate poisoning in humans based on sociodemographic and role of neurotransmitters with survival study in South India

The aim of this study was to investigate the sociodemographic characteristics of patients based on the poison chosen and different types of organophosphorus compounds. The data were collected to explore the sociodemographic characteristics of organophosphate (OP)-poisoned patients based on the source, site, and route of poisoning, education level, occupational status, and the purpose of poisoning. Furthermore, we estimated the serotonin and dopamine levels in the plasma samples of patients, and survival plots were also described. During the study of OP pesticide poisoning in 116 human subjects and 5 healthy volunteers, we observed, based on the survival plot, that75.9% of the patients were discharged, and the remaining patients died (24.1% of the patients) due to respiratory failure followed by cardiac arrest. Our findings suggest that the serotonin levels significantly (p < 0.01 and p < 0.001) decreased from 12 to 36 h, whereas the dopamine levels slightly increased from 12 to 36 h in the group with OP poisoning compared to the control group. Based on these findings, this study may aid in deciphering the precise mechanism by which pesticides cause behavioural changes that influence serotonin and dopamine levels in OP-poisoned patients. The purpose of this work was to serve as a small reminder of the risk to public health associated with organophosphate pesticides.

Organophosphates pesticide poisoning: a peculiar case report

Background: Acute organophosphate (OP) intoxication occurs following the absorption through gastrointestinal or respiratory tract, skin and rarely by intramuscular or intravenous route; in most cases is the result of suicidal attempt. These anticholinesterase compounds cause an acute cholinergic syndrome (with decreased consciousness, respiratory failure), an intermediate syndrome after 2 or 3 days from exposure (that requires prolonged ventilation), and finally a delayed neuropathy. In most cases an acute respiratory failure, by central and peripheral mechanisms, is the primary cause of death.

Clinical Profile of Adult Organophosphorus Compound Poisoning in a Tertiary Care Hospital

Despite the apparent benefits of organophosphate compounds (OPCs) acute organophosphate (OP) pesticide poisoning is an increasing problem worldwide. In a country like Bangladesh, where agriculture is a major component of the economy, these compounds are readily available to the general public. There is paucity of evidence from Bangladesh showing the pattern of organophosphate poisoning (OPP) in healthcare facilities. The aim of this study is to see the clinical profile of organophosphorus compound poisoning in admitted patients of tertiary care hospital.&#x0D; Methods: This observational cross-sectional study was carried out over all admitted patient with OPC poisoning in the department of Medicine, Cumilla Medical college, Cumilla from July 2019 to January 2020. A total of 100 cases were enrolled in the study. Patients having history of poisoning with OPC compound were stabilized by ABC care system and then assessed according to detailed history, physical examination and paradeniya organophosphorus poisoning (POP) scale.&#x0D; Results: The mean age was found 25.0±8.0 years and male to female ratio was 1:1.2, were mostly married (78.0%) and most of them from poor family (86%). The commonest manner of poisoning was suicidal (90.0%) with oral ingestion. More than eighty (84.0%) percent patients came from rural area. Commonest symptoms were abdominal pain (88.0%), vomiting (63.0%), excessive sweating (58.0%), salivation (35.0%), breathlessness (34.0%) and lacrimation (27.0%). Total hospitalization period was more than one week and less than two weeks in majority of cases (73%) and mortality rate was 2.0%.&#x0D; Conclusion: Due to increasing numbers of organophosphorus poisoning cases in younger age groups strict legislature on the availability of organophosphate compounds, preventive measures and appropriate health education should be introduced to decrease the incidence.&#x0D; Central Medical College Journal Vol 5 No 2 Jul 2021 PP 76-83

Molecular Mechanisms of Acute Organophosphate Nephrotoxicity.

Organophosphates (OPs) are toxic chemicals produced by an esterification process and some other routes. They are the main components of herbicides, pesticides, and insecticides and are also widely used in the production of plastics and solvents. Acute or chronic exposure to OPs can manifest in various levels of toxicity to humans, animals, plants, and insects. OPs containing insecticides were widely used in many countries during the 20th century, and some of them continue to be used today. In particular, 36 OPs have been registered in the USA, and all of them have the potential to cause acute and sub-acute toxicity. Renal damage and impairment of kidney function after exposure to OPs, accompanied by the development of clinical manifestations of poisoning back in the early 1990s of the last century, was considered a rare manifestation of their toxicity. However, since the beginning of the 21st century, nephrotoxicity of OPs as a manifestation of delayed toxicity is the subject of greater attention of researchers. In this article, we present a modern view on the molecular pathophysiological mechanisms of acute nephrotoxicity of organophosphate compounds.

Polyethyleneglycol-serine nanoparticles as a novel antidote for organophosphate poisoning: synthesis, characterization, in vitro and in vivo studies

Acute organophosphate pesticide poisoning causes considerable worldwide mortality and morbidity. In this study, serine was attached to the polyethylene glycol-bisaldehyde (PEG) as a novel antidote for diazinon (DZ) poisoning. Serine and PEG were conjugated with a reductive amination reaction. PEG-serine NPs (PEG-NPs) were purified and their structure was analyzed by 1H NMR, 13 C NMR, IR, and particle size was determined via dynamic light scattering. In vitro studies, including hemolysis assay and cytotoxicity on SK-BR-3 and HFFF2 cell lines, were performed. In vivo studies of PEG-NPs were evaluated on DZ-exposed mice. PEG-NPs were administered (i.p.) 20 min after a single dose of DZ (LD50; 166 mg/kg). Atropine (20 mg/kg, i.p.) with pralidoxime (20 mg/kg, i.p.) was used as the standard therapy compared to PEG-NPs. NMR and IR data confirmed that the conjugation of PEG to serine occurred successfully. The average NP size was 22.1 ± 1.8 nm. The hemolysis of the PEG-NPs was calculated at 0.867%, 50% inhibitory concentration (IC50) was calculated 36 ± 4.5, and 41 ± 3.4 mg/mL on SK-BR-3 and HFFF2 cell lines, respectively. Percentage of surviving significantly improved by 12.5, 25, and 25% through the usage of PEG-NPs at doses of 100, 200, and 400 mg/kg, respectively, when compared with the DZ group. Cholinesterase enzyme activity, lipid peroxidation, and mitochondrial function significantly improved through PEG-NPs when compared with the DZ group. PEG conjugated serine is very biocompatible with low toxicity and can reduce the acute toxicity of DZ as a new combination therapy.

Microglia Remodelling and Neuroinflammation Parallel Neuronal Hyperactivation Following Acute Organophosphate Poisoning.

Organophosphate (OP) compounds include highly toxic chemicals widely used both as pesticides and as warfare nerve agents. Existing countermeasures are lifesaving, but do not alleviate all long-term neurological sequelae, making OP poisoning a public health concern worldwide and the search for fully efficient antidotes an urgent need. OPs cause irreversible acetylcholinesterase (AChE) inhibition, inducing the so-called cholinergic syndrome characterized by peripheral manifestations and seizures associated with permanent psychomotor deficits. Besides immediate neurotoxicity, recent data have also identified neuroinflammation and microglia activation as two processes that likely play an important, albeit poorly understood, role in the physiopathology of OP intoxication and its long-term consequences. To gain insight into the response of microglia to OP poisoning, we used a previously described model of diisopropylfluorophosphate (DFP) intoxication of zebrafish larvae. This model reproduces almost all the defects seen in poisoned humans and preclinical models, including AChE inhibition, neuronal epileptiform hyperexcitation, and increased neuronal death. Here, we investigated in vivo the consequences of acute DFP exposure on microglia morphology and behaviour, and on the expression of a set of pro- and anti-inflammatory cytokines. We also used a genetic method of microglial ablation to evaluate the role in the OP-induced neuropathology. We first showed that DFP intoxication rapidly induced deep microglial phenotypic remodelling resembling that seen in M1-type activated macrophages and characterized by an amoeboid morphology, reduced branching, and increased mobility. DFP intoxication also caused massive expression of genes encoding pro-inflammatory cytokines Il1β, Tnfα, Il8, and to a lesser extent, immuno-modulatory cytokine Il4, suggesting complex microglial reprogramming that included neuroinflammatory activities. Finally, microglia-depleted larvae were instrumental in showing that microglia were major actors in DFP-induced neuroinflammation and, more importantly, that OP-induced neuronal hyperactivation was markedly reduced in larvae fully devoid of microglia. DFP poisoning rapidly triggered massive microglia-mediated neuroinflammation, probably as a result of DFP-induced neuronal hyperexcitation, which in turn further exacerbated neuronal activation. Microglia are thus a relevant therapeutic target, and identifying substances reducing microglial activation could add efficacy to existing OP antidote cocktails.