Connectivity between surface and interior in catalytic subunits of acetylcholinesterases inferred from their X-ray structures.

Catalytic activity and function of acetylcholinesterase (AChE; EC 3.1.1.7) have been recognized and studied for over a century and its quaternary and primary structures for about half a century, and its tertiary structure has been known for about 33 years. Clear understanding of relationships between the structure and the function is still pending for this enzyme. Hundreds of crystallographic, static snapshots of AChEs from different sources reveal largely one general backbone conformation with narrow entry into the active center gorge, tightly fit to accept one acetylcholine (ACh) molecule, in contrast to its high catalytic turnover. This short review of available X-ray structures of AChEs from electric ray Torpedo californica, mouse and human, finds some limited, yet consistent deviations in conformations of selected secondary structure elements of AChE relevant for its function. The observed conformational diversity of the acyl pocket loop of AChE, unlike the large Ω-loop, appears consistent with structurally dynamic INS data and solution-based SAXS experiments to explain its dominant role in controlling the size of the active center gorge opening, as well as connectivity between the immediate surroundings of the buried active Ser, and catalytically relevant sites on the AChE surface.

Photoelectrochemical Solution Gated Graphene Field-Effect Transistor Functionalized by Enzymatic Cascade Reaction for Organophosphate Detection.

Solution Gated Graphene Field-Effect Transistors (SGGT) are eagerly anticipated as an amplification platform for fabricating advanced ultra-sensitive sensors, allowing significant modulation of the drain current with minimal gate voltage. However, few studies have focused on light-matter interplay gating control for SGGT. Herein, this challenge is addressed by creating an innovative photoelectrochemical solution-gated graphene field-effect transistor (PEC-SGGT) functionalized with enzyme cascade reactions (ECR) for Organophosphorus (OPs) detection. The ECR system, consisting of acetylcholinesterase (AChE) and CuBTC nanomimetic enzymes, selectively recognizes OPs and forms o-phenylenediamine (oPD) oligomers sediment on the PEC electrode, with layer thickness related to the OPs concentration, demonstrating time-integrated amplification. Under light stimulation, the additional photovoltage generated on the PEC gate electrode is influenced by the oPD oligomers sediment layer, creating a differentiated voltage distribution along the gate path. PEC-SGGT, inherently equipped with built-in amplification circuits, sensitively captures gate voltage changes and delivers output with an impressive thousandfold current gain. The seamless integration of these three amplification modes in this advanced sensor allows a good linear range and highly sensitive detection of OPs, with a detection limit as low as 0.05 pm. This work provides a proof-of-concept for the feasibility of light-assisted functionalized gate-controlled PEC-SGGT for small molecule detection.

Efficacy of a combined anti-seizure treatment against cholinergic established status epilepticus following a sarin nerve agent insult in rats.

The development of refractory status epilepticus (SE) following sarin intoxication presents a therapeutic challenge. Here, we evaluated the efficacy of delayed combined double or triple treatment in reducing abnormal epileptiform seizure activity (ESA) and the ensuing long-term neuronal insult. SE was induced in rats by exposure to 1.2 LD50 sarin followed by treatment with atropine and TMB4 (TA) 1 min later. Double treatment with ketamine and midazolam or triple treatment with ketamine, midazolam and levetiracetam was administered 30 min post-exposure, and the results were compared to those of single treatment with midazolam alone or triple treatment with ketamine, midazolam, and valproate, which was previously shown to ameliorate this neurological insult. Toxicity and electrocorticogram activity were monitored during the first week, and behavioral evaluations were performed 2 weeks post-exposure, followed by biochemical and immunohistopathological analyses. Both double and triple treatment reduced mortality and enhanced weight recovery compared to TA-only treatment. Triple treatment and, to a lesser extent, double treatment significantly ameliorated the ESA duration. Compared to the TA-only or the TA+ midazolam treatment, both double and triple treatment reduced the sarin-induced increase in the neuroinflammatory marker PGE2 and the brain damage marker TSPO and decreased gliosis, astrocytosis and neuronal damage. Finally, both double and triple treatment prevented a change in behavior, as measured in the open field test. No significant difference was observed between the efficacies of the two triple treatments, and both triple combinations completely prevented brain injury (no differences from the naïve rats). Delayed double and, to a greater extent, triple treatment may serve as an efficacious delayed therapy, preventing brain insult propagation following sarin-induced refractory SE.

Bioremediation and bioscavenging for elimination of organophosphorus threats: An approach using enzymatic advancements.

Organophosphorus compounds (OP) are highly toxic pesticides and nerve agents widely used in agriculture and chemical warfare. The extensive use of these chemicals has severe environmental implications, such as contamination of soil, water bodies, and food chains, thus endangering ecosystems and biodiversity. Plants absorb pesticide residues, which then enter the food chain and accumulate in the body fat of both humans and animals. Numerous human cases of OP poisoning have been linked to both acute and long-term exposure to these toxic OP compounds. These compounds inhibit the action of the acetylcholinesterase enzyme (AChE) by phosphorylation, which prevents the breakdown of acetylcholine (ACh) neurotransmitter into choline and acetate. Thus, it becomes vital to cleanse the environment from these chemicals utilizing various physical, chemical, and biological methods. Biological methods encompassing bioremediation using immobilized microbes and enzymes have emerged as environment-friendly and cost-effective approaches for pesticide removal. Cell/enzyme immobilized systems offer higher stability, reusability, and ease of product recovery, making them ideal tools for OP bioremediation. Interestingly, enzymatic bioscavengers (stoichiometric, pseudo-catalytic, and catalytic) play a vital role in detoxifying pesticides from the human body. Catalytic bioscavenging enzymes such as Organophosphate Hydrolase, Organophosphorus acid anhydrolase, and Paraoxonase 1 show high degradation efficiency within the animal body as well as in the environment. Moreover, these enzymes can also be employed to decontaminate pesticides from food, ensuring food safety and thus minimizing human exposure. This review aims to provide insights to potential collaborators in research organizations, government bodies, and industries to bring advancements in the field of bioremediation and bioscavenging technologies for the mitigation of OP-induced health hazards.

Prenatal and childhood exposure to organophosphate pesticides and functional brain imaging in young adults.

BACKGROUND: Early life exposure to organophosphate (OP) pesticides has been linked with poorer neurodevelopment from infancy to adolescence. In our Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) birth cohort, we previously reported that residential proximity to OP use during pregnancy was associated with altered cortical activation using functional near infrared spectroscopy (fNIRS) in a small subset (n = 95) of participants at age 16 years. METHODS: We administered fNIRS to 291 CHAMACOS young adults at the 18-year visit. Using covariate-adjusted regression models, we estimated associations of prenatal and childhood urinary dialkylphosphates (DAPs), non-specific OP metabolites, with cortical activation in the frontal, temporal, and parietal regions of the brain during tasks of executive function and semantic language. RESULTS: There were some suggestive associations for prenatal DAPs with altered activation patterns in both the inferior frontal and inferior parietal lobes of the left hemisphere during a task of cognitive flexibility (ß per ten-fold increase in DAPs = 3.37; 95% CI: -0.02, 6.77 and ß = 3.43; 95% CI: 0.64, 6.22, respectively) and the inferior and superior frontal pole/dorsolateral prefrontal cortex of the right hemisphere during the letter retrieval working memory task (ß = -3.10; 95% CI: -6.43, 0.22 and ß = -3.67; 95% CI: -7.94, 0.59, respectively). We did not observe alterations in cortical activation with prenatal DAPs during a semantic language task or with childhood DAPs during any task. DISCUSSION: We observed associations of prenatal OP concentrations with mild alterations in cortical activation during tasks of executive function. Associations with childhood exposure were null. This is reasonably consistent with studies of prenatal OPs and neuropsychological measures of attention and executive function found in CHAMACOS and other birth cohorts.

Recombinant Organophosphorus acid anhydrolase (OPAA) enzyme-carbon quantum dot (CQDs)-immobilized thin film biosensors for the specific detection of Ethyl Paraoxon and Methyl Parathion in water resources.

Organophosphates pesticide (OP) toxicity through water resources is a large concern globally among all the emerging pollutants. Detection of OPs is a challenge which needs to be addressed considering the hazardous effects on the health of human beings. In the current research thin film biosensors of recombinant, Organophosphorus acid anhydrolase (OPAA) enzyme along with carbon quantum dots (CQDs) immobilized in thin films were developed. OPAA-CQDs thin film biosensors were used for the specific detection of two OPs Ethyl Paraoxon (EP) and Methyl Parathion (MP) in river water and household water supply. Recombinant OPAA enzyme was expressed in E. Coli, purified and immobilized on the CQD containing chitosan thin films. The CQDs used for this purpose were developed by a one-pot hydrothermal method from phthalic acid and Tri ethylene diamine. The properties of CQDs, OPAA and thin films were characterized using techniques like XPS, TEM, XRD, enzyme activity and CLSM measurements. Biosensing studies of EP and MP were performed by taking fluorescence measurements using a fiber optic spectrometer. The analytical parameters of biosensing were compared against an estimation carried out using the HPLC method. The biosensing performance indicates that the OPAA-CQDs thin film-based biosensors were able to detect both EP and MP in a range of 0-100 µM having a detection limit of 0.18 ppm/0.69 ppm for EP/MP, respectively with a response time of 5 min. The accuracy of estimation of EP/MP when spiked in water resources lie in the range of ∼100-102% which clearly indicates the OPAA-CQD based thin film biosensors can function as a point-of-use method for the detection of OP pesticides in complex water resources.

Developing a Multi-Spectral NIR LED-Based Instrument for the Detection of Pesticide Residues Containing Chlorpyrifos-Methyl in Rough, Brown, and Milled Rice.

A recent study showed the potential of the DA Perten 7200 NIR Spectrometer in detecting chlorpyrifos-methyl pesticide residue in rough, brown, and milled rice. However, this instrument is still lab-based and generally suited for point-of-sale testing. To provide a field-deployable version of this technique, an existing light emitting diode (LED)-based instrument that provides discrete NIR wavelength illumination and reflectance spectra over the range of 850-1550 nm was tested. Spectra were collected from rough, brown, and milled rice at different pesticide concentrations and analyzed for quantitative and qualitative measurement using partial least squares regression (PLS) and discriminant analysis (DA). Simulations for two LED-based instruments were also evaluated using corresponding segments of spectra from the DA7200 to represent LED illumination. For the simulation of the existing LED-based instrument (LEDPrototype1) fitted with 850, 910, 940, 970, 1070, 1200, 1300, 1450, and 1550 nm LED wavelengths, resulting R2 ranged from 0.52 to 0.71, and the correct classification was 70.4% to 100%. The simulation of a second LED instrument (LEDPrototype2) fitted with 980, 1050, 1200, 1300, 1450, 1550, 1600, and 1650 nm LED wavelengths showed R2 of 0.59 to 0.82 and correct classifications of 66% to 100%. These LED wavelengths were selected based on the significant wavelength regions from the PLS regression coefficients of DA7200 and the commercial availability of LED wavelengths. Results showed that it is possible to use a multi-spectral LED-based instrument to detect varying levels of chlorpyrifos-methyl pesticide residue in rough, brown, and milled rice.

Gestational Exposure to Common Endocrine Disrupting Chemicals and Their Impact on Neurodevelopment and Behavior.

Endocrine disrupting chemicals are common in our environment and act on hormone systems and signaling pathways to alter physiological homeostasis. Gestational exposure can disrupt developmental programs, permanently altering tissues with impacts lasting into adulthood. The brain is a critical target for developmental endocrine disruption, resulting in altered neuroendocrine control of hormonal signaling, altered neurotransmitter control of nervous system function, and fundamental changes in behaviors such as learning, memory, and social interactions. Human cohort studies reveal correlations between maternal/fetal exposure to endocrine disruptors and incidence of neurodevelopmental disorders. Here, we summarize the major literature findings of endocrine disruption of neurodevelopment and concomitant changes in behavior by four major endocrine disruptor classes:bisphenol A, polychlorinated biphenyls, organophosphates, and polybrominated diphenyl ethers. We specifically review studies of gestational and/or lactational exposure to understand the effects of early life exposure to these compounds and summarize animal studies that help explain human correlative data.

Organophosphates as Versatile Substrates in Organic Synthesis.

This review summarizes the applications of organophosphates in organic synthesis. After a brief introduction, it discusses cross-coupling reactions, including both transition-metal-catalyzed and transition-metal-free substitution reactions. Subsequently, oxidation and reduction reactions are described. In addition, this review highlights the applications of organophosphates in the synthesis of natural compounds, demonstrating their versatility and importance in modern synthetic chemistry.

Assessing the effect of ß-glucan diets on innate immune response of tilapia macrophages against trichlorfon exposure: an in vitro study.

The widespread use of pesticides in some areas where fish species such as tilapia are farmed may cause damage to the environment and affect commercial fish and therefore, human health. Water leaching with the pesticide trichlorfon, during the fumigation season in the field, can affect water quality in fish farms and consequently affect fish health. At the same time, the use of immunomodulatory compounds such as ß-glucan supplied in the diet has become widespread in fish farms as it has been shown that improves the overall immune response. The present research examines the immunomodulatory impacts observed in macrophages of Nile tilapia (Oreochromis niloticus) after being fed a diet supplemented with ß-glucan for 15 days, followed by their in vitro exposure to trichlorfon, an organophosphate pesticide, at concentrations of 100 and 500 µg mL-1 for 24 h. The results showed that ß-glucan diet improved the viability of cells exposed to trichlorfon and their antioxidant capacity. However, ß-glucan did not counteract the effects of the pesticide as for the ability to protect against bacterial infection. From the present results, it can be concluded that ß-glucan feeding exerted a protective role against oxidative damage in cells, but it was not enough to reduce the deleterious effects of trichlorfon on the microbicidal capacity of macrophages exposed to this pesticide.

Effects of organophosphates on precision-cut kidney slices.

Organophosphate (OP) poisoning, both accidental and with suicidal intent, is a global medical challenge. While the primary toxicity of these pesticides is based on the inhibition of acetylcholinesterase (AChE), case reports describe patients developing OP-mediated renal insufficiency. We set out to investigate possible pathomechanisms utilizing rat precision-cut kidney slices (PCKS). Depending on the method of investigation, PCKS were observed for a maximum of 10 days. PCKS exposed to OP compounds (malaoxon, malathion, paraoxon, parathion) showed a dose-dependent loss of viability and a reduction of total protein content over the course of 10 days. A concentration of 500 µM OP showed the most differences between OP compounds. After two days of incubation parathion showed a significantly lower level of viability than malathion. The respective effects of paraoxon and malaoxon were not significantly different from the control. However, effects of OP were only observed in concentrations exceeding those that were needed to achieve significant AChE inhibition in rat kidney tissue. In addition, we observed histological changes, without inducing LDH leakage. Overall, results suggest that OP exert effects in kidney tissue, that exceed those expected from the sole inhibition of AChE and vary between compounds. Without signs of necrosis, findings call for studies that address other possible pathomechanisms, including inflammatory response, oxidative stress or activation of apoptosis to further understand the nephrotoxicity of OP compounds. Monitoring oxon concentration over time, we demonstrated reduced enzyme-inhibiting properties in the presence of PCKS, suggesting interactions between OP compound and kidney tissue.

Organophosphate pesticide-induced toxicity through DNA damage and DNA repair mechanisms.

Organophosphate pesticides (OPs) are widely used in agriculture, healthcare, and other industries due to their ability to kill pests. However, OPs can also have genotoxic effects on humans who are exposed to them. This review summarizes the research on DNA damage caused by OPs, the mechanisms behind this damage, and the resulting cellular effects. Even at low doses, OPs have been shown to damage DNA and cause cellular dysfunction. Common phenomena seen in cells that are exposed to OPs include the formation of DNA adducts and lesions, single-strand and double-strand DNA breaks, and DNA and protein inter and intra-cross-links. The present review will aid in comprehending the extent of genetic damage and the impact on DNA repair pathways caused by acute or chronic exposure to OPs. Additionally, understanding the mechanisms of the effects of OPs will aid in correlating them with various diseases, including cancer, Alzheimer's, and Parkinson's disease. Overall, knowledge of the potential adverse effects of different OPs will help in monitoring the health complications they may cause.

Associations between prenatal organophosphate pesticide exposure and placental gene networks.

BACKGROUND: Exposure to organophosphate (OP) pesticides during pregnancy has been linked to deficiencies of neurobehavioral development in childhood; however, the molecular mechanisms underlying this association remain elusive. The placenta plays a crucial role in protecting the fetus from environmental insults and safeguarding proper fetal development including neurodevelopment. The aim of our study is to evaluate changes in the placental transcriptome associated with prenatal OP exposure. METHODS: Pregnant farm workers from two agricultural districts in northern Thailand were recruited for the Study of Asian Women and Offspring's Development and Environmental Exposures (SAWASDEE) from 2017 to 2019. For 254 participants, we measured maternal urinary concentrations of six nonspecific dialkyl phosphates (DAP) metabolites in early, middle, and late pregnancy. In parallel, we profiled the term placental transcriptome from the same participants using RNA-Sequencing and performed Weighted Gene co-expression Network Analysis (WGCNA). Generalized linear regression modeling was used to examine associations of urinary OP metabolites and placental co-expression module eigenvalues. RESULTS: We identified 21 gene co-expression modules in the placenta. From the six DAP metabolites assayed, diethylphosphate (DEP) and diethylthiophosphate (DETP) were detected in more than 70% of the urine samples. Significant associations between DEP at multiple time points and two specific placental gene modules were observed. The 'black' module, enriched in genes involved in epithelial-to-mesenchymal transition (EMT) and hypoxia, was negatively associated with DEP in early (p = 0.034), and late pregnancies (p = 0.016). The 'lightgreen' module, enriched in genes involved in myogenesis and EMT, was negatively associated with DEP in late pregnancy (p = 0.010). We observed 2 hub genes (CELSR1 and PYCR1) of the 'black' module to be negatively associated with DEP in early and late pregnancies. CONCLUSIONS: Our results suggest that prenatal OP exposure may disrupt placental gene networks in a time-dependent manner. Such transcriptomic effects may lead to down-stream changes in placental function that ultimately affect the developing fetus.

Health consequences of exposure to aircraft contaminated air and fume events: a narrative review and medical protocol for the investigation of exposed aircrew and passengers.

Thermally degraded engine oil and hydraulic fluid fumes contaminating aircraft cabin air conditioning systems have been well documented since the 1950s. Whilst organophosphates have been the main subject of interest, oil and hydraulic fumes in the air supply also contain ultrafine particles, numerous volatile organic hydrocarbons and thermally degraded products. We review the literature on the effects of fume events on aircrew health. Inhalation of these potentially toxic fumes is increasingly recognised to cause acute and long-term neurological, respiratory, cardiological and other symptoms. Cumulative exposure to regular small doses of toxic fumes is potentially damaging to health and may be exacerbated by a single higher-level exposure. Assessment is complex because of the limitations of considering the toxicity of individual substances in complex heated mixtures.There is a need for a systematic and consistent approach to diagnosis and treatment of persons who have been exposed to toxic fumes in aircraft cabins. The medical protocol presented in this paper has been written by internationally recognised experts and presents a consensus approach to the recognition, investigation and management of persons suffering from the toxic effects of inhaling thermally degraded engine oil and other fluids contaminating the air conditioning systems in aircraft, and includes actions and investigations for in-flight, immediately post-flight and late subsequent follow up.

Frequency and polymorphism of acetylcholinesterase gene involved in the organophosphate resistance of Musca domestica in Guizhou Province, China.

Organophosphate (OP) resistance has been prevalent in Musca domestica populations worldwide since 1960s. Previous studies have demonstrated that point mutations of the acetylcholinesterase gene (Ace) are one of the important molecular mechanisms underlying OP resistance. However, few studies have investigated the molecular mechanisms of OP resistance in the past 10 years in China. In this study, we investigated the status of OP resistance and genetic diversity of Ace in the field populations of houseflies in Guizhou Province of China. The bioassays showed that the houseflies had 142-304-fold resistance to dichlorvos (DDVP) and 122-364-fold resistance to temephos, compared to the susceptible houseflies. Five nonsynonymous mutations (Y226F, V260L, G342A/V, F407Y) in Ace were detected among the 7 field populations, with an average frequency of 5.4%, 55%, 68%, 32%, and 94%, respectively, of which the Y226F mutation had not been reported previously. Eleven combinations of triple mutations (at positions 260, 342, and 407) were observed, of which the combination 260L/V+342A/V+407Y was predominant. The ZY and AS populations showed greatest diversity of allelic combination and the other five populations showed different distributions among different regions. These results indicate that the resistance to OPs is prevalent among the housefly populations and target-site insensitivity is the main cause of resistance in Guizhou Province. The difference in distribution and the allelic diversity of Ace in field populations may be due to the complexity and variability of insecticide application. It is necessary to monitor resistance to insecticides and conduct management of houseflies in Guizhou Province.

Brain-targeted nanoreactors prevent the development of organophosphate-induced delayed neurological damage.

BACKGROUND: Organophosphate (OP)-induced delayed neurological damage is attributed to permanent neuropathological lesions caused by irreversible OP-neurocyte interactions, without potent brain-targeted etiological antidotes to date. The development of alternative therapies to achieve intracerebral OP detoxification is urgently needed. METHODS: We designed a brain-targeted nanoreactor by integrating enzyme immobilization and biomimetic membrane camouflaging protocols with careful characterization, and then examined its blood-brain barrier (BBB) permeability both in vitro and in vivo. Subsequently, the oxidative stress parameters, neuroinflammatory factors, apoptotic proteins and histopathological changes were measured and neurobehavioral tests were performed. RESULTS: The well-characterized nanoreactors exerted favourable BBB penetration capability both in vitro and in vivo, significantly inhibiting OP-induced intracerebral damage. At the cellular and tissue levels, nanoreactors obviously blocked oxidative stress, cellular apoptosis, inflammatory reactions and brain histopathological damage. Furthermore, nanoreactors radically prevented the occurrence of OP-induced delayed cognitive deficits and psychiatric abnormality. CONCLUSION: The nanoreactors significantly prevented the development of OP-induced delayed neurological damage, suggesting a potential brain-targeted etiological strategy to attenuate OP-related delayed neurological and neurobehavioral disorders.

Neurotoxicity evoked by organophosphates and available countermeasures.

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABAAR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.

Differentiated SH-SY5Y neuroblastoma cells as a model for evaluation of nerve agent-associated neurotoxicity.

Organophosphorus compounds (OPs) involving life-threatening nerve agents (NA) have been known for several decades. Despite a clear mechanism of their lethality caused by the irreversible inhibition of acetylcholinesterase (AChE) and manifested via overstimulation of peripheral nicotinic and muscarinic acetylcholine (ACh) receptors, the mechanism for central neurotoxicity responsible for acute or delayed symptoms of the poisoning has not been thoroughly uncovered. One of the reasons is the lack of a suitable model. In our study, we have chosen the SH-SY5Y model in both the differentiated and undifferentiated state to study the effects of NAs (GB, VX and A234). The activity of expressed AChE in cell lysate assessed by Ellman's method showed 7.3-times higher activity in differentiated SH-SY5Y cells in contrast to undifferentiated cells, and with no involvement of BuChE as proved by ethopropazine (20 µM). The activity of AChE was found to be, in comparison to untreated cells, 16-, 9.3-, and 1.9-times lower upon A234, VX, and GB (100 µM) administration respectively. The cytotoxic effect of given OPs expressed as the IC50 values for differentiated and undifferentiated SH-SY5Y, respectively, was found 12 mM and 5.7 mM (A234), 4.8 mM and 1.1 mM (VX) and 2.6 mM and 3.8 mM (GB). In summary, although our results confirm higher AChE expression in the differentiated SH-SY5Y cell model, the such higher expression does not lead to a more pronounced NA cytotoxic effect. On the contrary, higher expression of AChE may attenuate NA-induced cytotoxicity by scavenging the NA. Such finding highlights a protective role for cholinesterases by scavenging Novichoks (A-agents). Second, we confirmed the mechanism of cytotoxicity of NAs, including A-agents, can be ascribed rather to the non-specific effects of OPs than to AChE-mediated effects.

Child and adolescent mortality associated with pesticide toxicity in Cape Town, South Africa, 2010-2019: a retrospective case review.

BACKGROUND: Poisoning of children after exposure to pesticides is a major public health concern, particularly in countries with poorer urban populations, such as South Africa. This may stem from the illegal distribution and domestic use of street pesticides, which are highly hazardous agricultural pesticides. The aim of this study was to profile paediatric deaths due to acute pesticide poisoning in the west-metropole of Cape Town, South Africa; to identify whether the active ingredients were highly hazardous pesticides according to the FAO and WHO; and to inform policy and public health interventions to prevent future exposures and mortality. METHODS: A retrospective and descriptive analysis of forensic post-mortem records (2010 to 2019) was conducted to identify cases of paediatric deaths (< 18 years old) in the west metropole of Cape Town, involving pesticide poisoning admitted to the Salt River mortuary (one out of 16 mortuaries in the Western Cape province). Demographic, circumstantial, autopsy, and toxicological information was captured. Descriptive statistics, together with chi-square tests, Fisher's probability tests, and Mann-Whitney U tests were used to analyse the data. RESULTS: In total, 54 paediatric pesticide deaths were identified, including 22 (40.7%) males and 32 (59.3%) females, out of 5,181 paediatric unnatural deaths admitted over the 10-year period. The median age of the decedents was 8.3 years (range: 1 day to 17.9 years), with the majority under five years (42.6%) or between 15 and 18 years old (40.7%). All incidents occurred in peri-urban areas of Cape Town, with most individuals being admitted to hospital (88.9%) for a median survival time of 4.8 h. Toxicological analysis was requested in 50 cases (92.6%) with the organophosphate pesticides terbufos (n = 29), methamidophos (n = 2) and diazinon (n = 2) detected most frequently. Adolescent (15-18 years) suicides (29.6%) and accidental child deaths (< 4 years) (18.5%) were common. CONCLUSIONS: Terbufos and methamidophos are highly hazardous pesticide (HHP) active ingredients registered in South Africa for agricultural uses, yet commonly sold as street pesticides for domestic use in lower socioeconomic areas. Reducing access and availability of toxic pesticides, especially through the illegal selling of street pesticides, and providing low toxic alternatives to poorer communities, may support mortality reduction initiatives. Mortality and toxicology data provide important, often overlooked, surveillance tools for informing policy and public health interventions to reduce toxic pesticide harm in local communities.

Influence of exposure to pesticides on telomere length and pregnancy outcome: Diethylphosphates but not Dimethylphosphates are associated with accelerated telomere attrition in a Palestinian cohort.

Exposure to environmental pesticides during pregnancy is associated with adverse health outcomes such as low birth weight and impaired neuro-development. In this study, we assessed maternal leukocyte telomere lengths (TL) in Palestinian pregnant women and compared the data with urinary organophosphate concentrations, demographic, lifestyle and dietary factors, birth weight, body length, gestational age, and head circumference. Women with high urine levels of creatinine adjusted diethylphosphate(DE)derived pesticide metabolites DEP, DETP or DEDTP had shorter telomeres (p = 0.05). Women living in proximity to agricultural fields had shorter telomeres compared to women not living in proximity to agricultural fields (p = 0.011). Regular consumption of organic food was associated with shorter telomeres (p = 0.01), whereas the consumption of other vegetables such as artichokes was rather associated with longer telomeres. By contrast, urine levels of dimethylphosphate(DM)-derived pesticide metabolites DMTP and DMDTP were associated with lower birth weight (p = 0.05) but not with shrter telomeres. In conclusion organophosphate pesticides and living in proximity to agriculture are associated with shorter TL, likely due to higher consumption of contaminated fruits and vegetables and/or the transport of pesticides to non-treatment sites. DE and DM substituted pesticides seem to have different effects on telomeres and development.