-
Scientific Reports Sep 2020Whether central apnoea or hypopnoea can be induced by organophosphorus poisoning remains unknown to date. By using the acute brainstem slice method and multi-electrode...
Whether central apnoea or hypopnoea can be induced by organophosphorus poisoning remains unknown to date. By using the acute brainstem slice method and multi-electrode array system, we established a paraoxon (a typical acetylcholinesterase inhibitor) poisoning model to investigate the time-dependent changes in respiratory burst amplitudes of the pre-Bötzinger complex (respiratory rhythm generator). We then determined whether pralidoxime or atropine, which are antidotes of paraoxon, could counteract the effects of paraoxon. Herein, we showed that paraoxon significantly decreased the respiratory burst amplitude of the pre-Bötzinger complex (p < 0.05). Moreover, pralidoxime and atropine could suppress the decrease in amplitude by paraoxon (p < 0.05). Paraoxon directly impaired the pre-Bötzinger complex, and the findings implied that this impairment caused central apnoea or hypopnoea. Pralidoxime and atropine could therapeutically attenuate the impairment. This study is the first to prove the usefulness of the multi-electrode array method for electrophysiological and toxicological studies in the mammalian brainstem.
Topics: Animals; Atropine; Brain; Organophosphate Poisoning; Paraoxon; Pralidoxime Compounds; Rats; Respiratory Burst; Sleep Apnea, Central
PubMed: 32985607
DOI: 10.1038/s41598-020-73003-5 -
Chemico-biological Interactions Nov 2016Paraoxonase-1 (PON1), an esterase/lactonase primarily associated with plasma high-density lipoprotein (HDL), was the first member of this family of enzymes to be...
Paraoxonase-1 (PON1), an esterase/lactonase primarily associated with plasma high-density lipoprotein (HDL), was the first member of this family of enzymes to be characterized. Its name was derived from its ability to hydrolyze paraoxon, the toxic metabolite of the insecticide parathion. Related enzymes PON2 and PON3 were named from their evolutionary relationship with PON1. Mice with each PON gene knocked out were generated at UCLA and have been key for elucidating their roles in organophosphorus (OP) metabolism, cardiovascular disease, innate immunity, obesity, and cancer. PON1 status, determined with two-substrate analyses, reveals an individual's functional Q192R genotype and activity levels. The three-dimensional structure for a chimeric PON1 has been useful for understanding the structural properties of PON1 and for engineering PON1 as a catalytic scavenger of OP compounds. All three PONs hydrolyze microbial N-acyl homoserine lactone quorum sensing factors, quenching Pseudomonas aeruginosa's pathogenesis. All three PONs modulate oxidative stress and inflammation. PON2 is localized in the mitochondria and endoplasmic reticulum. PON2 has potent antioxidant properties and is found at 3- to 4-fold higher levels in females than males, providing increased protection against oxidative stress, as observed in primary cultures of neurons and astrocytes from female mice compared with male mice. The higher levels of PON2 in females may explain the lower frequency of neurological and cardiovascular diseases in females and the ability to identify males but not females with Parkinson's disease using a special PON1 status assay. Less is known about PON3; however, recent experiments with PON3 knockout mice show them to be susceptible to obesity, gallstone formation and atherosclerosis. Like PONs 1 and 2, PON3 also appears to modulate oxidative stress. It is localized in the endoplasmic reticulum, mitochondria and on HDL. Both PON2 and PON3 are upregulated in cancer, favoring tumor progression through mitochondrial protection against oxidative stress and apoptosis.
Topics: Animals; Aryldialkylphosphatase; Astrocytes; Carotid Artery Diseases; Cells, Cultured; Clopidogrel; Endoplasmic Reticulum; Female; Genotype; Homocysteine; Humans; Inflammation; Lipid Metabolism; Lipoproteins, HDL; Male; Mice; Mice, Knockout; Mitochondria; Neurons; Organophosphorus Compounds; Oxidative Stress; Platelet Aggregation Inhibitors; Quorum Sensing; Ticlopidine
PubMed: 27238723
DOI: 10.1016/j.cbi.2016.05.036 -
Journal of Alzheimer's Disease : JAD 2021Identification of modifiable risk factors that affect cognitive decline is important for the development of preventive and treatment strategies. Status of paraoxonase 1... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Identification of modifiable risk factors that affect cognitive decline is important for the development of preventive and treatment strategies. Status of paraoxonase 1 (PON1), a high-density lipoprotein-associated enzyme, may play a role in the development of neurological diseases, including Alzheimer's disease.
OBJECTIVE
We tested a hypothesis that PON1 status predicts cognition in individuals with mild cognitive impairment (MCI).
METHODS
Individuals with MCI (n = 196, 76.8-years-old, 60% women) participating in a randomized, double-blind placebo-controlled trial (VITACOG) were assigned to receive a daily dose of folic acid (0.8 mg), vitamin B12 (0.5 mg) and B6 (20 mg) (n = 95) or placebo (n = 101) for 2 years. Cognition was analyzed by neuropsychological tests. Brain atrophy was quantified in a subset of participants (n = 168) by MRI. PON1 status, including PON1 Q192R genotype, was determined by quantifying enzymatic activity of PON1 using paraoxon and phenyl acetate as substrates.
RESULTS
In the placebo group, baseline phenylacetate hydrolase (PhAcase) activity of PON1 (but not paraoxonase activity or PON1 Q192R genotype) was significantly associated with global cognition (Mini-Mental State Examination, MMSE; Telephone Inventory for Cognitive Status-modified, TICS-m), verbal episodic memory (Hopkins Verbal Learning Test-revised: Total Recall, HVLT-TR; Delayed Recall, HVLT-DR), and attention/processing speed (Trail Making A and Symbol Digits Modalities Test, SDMT) at the end of study. In addition to PhAcase, baseline iron and triglycerides predicted MMSE, baseline fatty acids predicted SDMT, baseline anti-N-Hcy-protein autoantibodies predicted TICS-m, SDMT, Trail Making A, while BDNF V66M genotype predicted HVLT-TR and HVLT-DR scores at the end of study. B-vitamins abrogated associations of PON1 and other variables with cognition.
CONCLUSION
PON1 is a new factor associated with impaired cognition that can be ameliorated by B-vitamins in individuals with MCI.
Topics: Aryldialkylphosphatase; Brain; Cognition; Cognitive Dysfunction; Dietary Supplements; Double-Blind Method; Female; Folic Acid; Humans; Magnetic Resonance Imaging; Male; Mass Spectrometry; Neuropsychological Tests; Vitamin B 12; Vitamin B 6; Vitamin B Complex
PubMed: 33935094
DOI: 10.3233/JAD-210137 -
EFSA Journal. European Food Safety... May 2022The identification of pollutants is crucial to protect water resources and ensure food safety. The available analytical methodologies allow reliable detection of organic...
The identification of pollutants is crucial to protect water resources and ensure food safety. The available analytical methodologies allow reliable detection of organic pollutants such as pesticides; however, there is the need for faster, direct and continuous methodologies for real-time monitoring of pesticides. Fluorescent-based biosensors have been recently proposed as a valid alternative due to their advantage of being easy, cheap and specific. In this context, the aim of the present EU-FORA fellowship programme was to develop and apply a fluorescence-based biosensing device for the detection of organophosphate (OP) pesticides in water samples and drinkable food. The study was addressed using a mutant of the thermostable esterase-2 from (EST2-S35C) as a bioreceptor for OP pesticides. The use of EST2 involves some significant advantages including specificity and affinity towards OPs, and high stability over time in a different range of temperatures and pH. The protein was labelled to the fluorescent probe IAEDANS and fluorescence measurements of quenching in solution and in immobilised form were performed. The results showed good stability and sensitivity, reaching low limits of detection and quantification and a constant signal intensity over time. The addition of paraoxon quenched the fluorescence of the complex, reaching a plateau at 100 pmol paraoxon. The decrease of enzymatic activity of EST2-S35C-IAEDANS in the presence of paraoxon correlated the inhibition of the labelled enzyme with the decrease in fluorescence. The results from the application of the biosensor with real samples showed a decrease in fluorescence in surface water samples, contaminated by OPs. The use of the developed fluorescence-based biosensor demonstrated its applicability for real samples monitoring and could ensure the production of large amounts of data in a short period of time which can be used to address environmental and food safety risk assessment.
PubMed: 35634553
DOI: 10.2903/j.efsa.2022.e200403 -
Toxics Sep 2023The contexts where there are mining and agriculture activities are potential sources of risk to human health due to contamination by chemical mixtures. These contexts...
The contexts where there are mining and agriculture activities are potential sources of risk to human health due to contamination by chemical mixtures. These contexts are frequent in several Colombian regions. This study explored the potential association between the frequency of micronuclei and pesticides and elements in regions with ferronickel (Montelibano, Córdoba) and gold (Nechí, Antioquia) mining, and a closed native mercury mine (Aranzazu, Caldas), with an emphasis in the potential effect of selenium as a potential chelator. A cross-sectional study was carried out with 247 individuals. Sociodemographic, occupational, and toxicological variables were ascertained. Blood and urine samples were taken for pesticide analysis (5 organophosphates, 4 organochlorines, and 3 carbamates), 68 elements were quantified in hair, and micronuclei were quantified in lymphocytes. The mixtures of elements were grouped through principal component analysis. Prevalence ratios were estimated with robust variance Poisson regressions to explore associations. Interactions of selenium with toxic elements were explored. The highest concentrations of elements were in the active mines. The potentially most toxic chemical mixture was observed in the ferronickel mine. Pesticides were detected in a low proportion of participants (<2.5%), except paraoxon-methyl in blood (27.55%) in Montelibano and paraoxon-ethyl in blood (18.81%) in Aranzazu. The frequency of micronuclei was similar in the three mining contexts, with means between 4 to 7 ( = 0.1298). There was great heterogeneity in the exposure to pesticides and elements. The "hormetic effect" of selenium was described, in which, at low doses, it acts as a chelator in Montelibano and Aranzazu, and at high doses, it can enhance the toxic effects of other elements, maybe as in Nechí. Selenium can serve as a protective agent, but it requires adaptation to the available concentrations in each region to avoid its toxic effects.
PubMed: 37888671
DOI: 10.3390/toxics11100821 -
Association of Paraoxonase-1 Genotype and Phenotype with Angiogram Positive Coronary Artery Disease.Arquivos Brasileiros de Cardiologia Oct 2022It has been shown that increased serum PON1 levels are protective against several disorders. Several single nucleotide polymorphisms (SNPs) of the PON1 gene have been...
BACKGROUND
It has been shown that increased serum PON1 levels are protective against several disorders. Several single nucleotide polymorphisms (SNPs) of the PON1 gene have been reported to be associated with serum enzyme protein levels and activity.
OBJECTIVE
To investigate the association of SNPs of PON1 and serum paraoxonase activity with coronary artery disease (CAD).
METHODS
A total of 601 unrelated patients who underwent coronary angiography including those who had >50% stenosis (N=266) and those with <30% stenosis (N=335) were studied. The Paraoxonase gene rs662 and rs840560 SNPs were determined using the ARMS-PCR method and the rs705379 SNP was genotyped using PCR-RFLP analysis. Serum paraoxonase activity was measured using paraoxon as a substrate. A p value of p<0.05 was considered as significant.
RESULTS
Serum paraoxonase activity was not significantly different between the study groups. After adjustment for age, sex, hypertension, diabetes mellitus and dyslipidemia, the GG genotype and co-dominant model of rs662 was positively associated with a positive angiogram (respectively, OR=2.424, 95%CI [1.123-5.233], p<0.05, OR=1.663, 95%CI [1.086-2.547]). Serum paraoxonase activity was significantly higher in the G allele and GG variant of rs662, A allele and AA variant of rs854560 and C allele and CC variant of rs705379. The haplotype analysis has shown that the ATC haplotype was significantly more prevalent among the angiogram negative group. The analysis between groups indicated that the A allele of rs662 was significantly associated with lower paraoxonase activity in the positive angiogram group (p=0.019).
CONCLUSIONS
The presence of the G allele of the rs662 single nucleotide polymorphism is independently associated to increased risk of CAD.
Topics: Humans; Aryldialkylphosphatase; Coronary Artery Disease; Paraoxon; Constriction, Pathologic; Genotype; Polymorphism, Single Nucleotide; Phenotype; Coronary Angiography
PubMed: 36074479
DOI: 10.36660/abc.20210422 -
Structure (London, England : 1993) Nov 2022Organophosphorus (OP) compounds, including nerve agents and some pesticides, covalently bind to the catalytic serine of human acetylcholinesterase (hAChE), thereby...
Organophosphorus (OP) compounds, including nerve agents and some pesticides, covalently bind to the catalytic serine of human acetylcholinesterase (hAChE), thereby inhibiting acetylcholine hydrolysis necessary for efficient neurotransmission. Oxime antidotes can reactivate the OP-conjugated hAChE, but reactivation efficiency can be low for pesticides, such as paraoxon (POX). Understanding structural and dynamic determinants of OP inhibition and reactivation can provide insights to design improved reactivators. Here, X-ray structures of hAChE with unaged POX, with POX and oximes MMB4 and RS170B, and with MMB4 are reported. A significant conformational distortion of the acyl loop was observed upon POX binding, being partially restored to the native conformation by oximes. Neutron vibrational spectroscopy combined with molecular dynamics simulations showed that picosecond vibrational dynamics of the acyl loop soften in the ∼20-50 cm frequency range. The acyl loop structural perturbations may be correlated with its picosecond vibrational dynamics to yield more comprehensive template for structure-based reactivator design.
Topics: Humans; Acetylcholinesterase; Paraoxon; Crystallography, X-Ray; Cholinesterase Inhibitors; Oximes; Organophosphorus Compounds; Neutrons; Pesticides
PubMed: 36265484
DOI: 10.1016/j.str.2022.09.006 -
Toxics Aug 2023Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce...
Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce Neurodevelopmental Toxicity (NDT) in animals and humans. The canonical mechanism of OP neurotoxicity involves the inhibition of acetylcholinesterase (AChE), but other mechanisms non-AChE are also involved and not fully understood. We used network toxicology and molecular docking to identify molecular targets and toxicity mechanisms common to OPs. Targets related to diazinon-oxon, chlorpyrifos oxon, and paraoxon OPs were predicted using the Swiss Target Prediction and PharmMapper databases. Targets related to NDT were compiled from GeneCards and OMIM databases. In order to construct the protein-protein interaction (PPI) network, the common targets between OPs and NDT were imported into the STRING. Network topological analyses identified EGFR, MET, HSP90AA1, and SRC as hub nodes common to the three OPs. Using the Reactome pathway and gene ontology, we found that signal transduction, axon guidance, cellular responses to stress, and glutamatergic signaling activation play key roles in OP-induced NDT.
PubMed: 37624215
DOI: 10.3390/toxics11080710 -
Pharmacology Research & Perspectives Feb 2015One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures...
One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures require activation of muscarinic acetylcholine receptors in the central nervous system. Seizures induced by the muscarinic agonist pilocarpine require the M1 receptor and are modulated by cannabinoid CB1 receptors. In this study, we determined whether M1 and CB1 receptors also regulated seizures induced by the organophosphate paraoxon. We found no differences in seizures induced by paraoxon in wild-type (WT) and M1 knockout (KO) mice, indicating that in contrast to pilocarpine seizures, M1 receptors are not required for paraoxon seizures. Furthermore, we found that pilocarpine administration resulted in seizure-independent activation of ERK in the hippocampus in a M1 receptor-dependent manner, while paraoxon did not induce seizure-independent activation of ERK in the mouse hippocampus. This shows that pilocarpine and paraoxon activated M1 receptors in the hippocampus to different extents. There were no differences in seizures induced by paraoxon in WT and CB1 KO mice, and neither CB1 agonist nor antagonist administration had significant effects on paraoxon seizures, indicating that, in contrast to pilocarpine seizures, paraoxon seizures are not modulated by CB1 receptors. These results demonstrate that there are fundamental molecular differences in the regulation of seizures induced by pilocarpine and paraoxon.
PubMed: 25692018
DOI: 10.1002/prp2.100 -
Annals of the New York Academy of... Jun 2016In addition to the global use of organophosphate (OP) pesticides for agriculture, OP nerve agents and pesticides have been employed on battlefields and by terrorists... (Review)
Review
In addition to the global use of organophosphate (OP) pesticides for agriculture, OP nerve agents and pesticides have been employed on battlefields and by terrorists (e.g., a recent sarin attack in Syria). These occurrences highlight the need for an effective countermeasure against OP exposure. Human butyrylcholinesterase (HuBChE) is a leading candidate, but injection of the high doses required for protection present pharmacokinetic challenges. An aerosolized recombinant form (aer-rHuBChE) that can neutralize inhaled OPs at the portal of entry has been assessed for its efficacy in protecting macaques against respiratory toxicity following inhalation exposure to the pesticide paraoxon (aer-Px). While protection in macaques has been demonstrated using the MicroSprayer® delivery device, administration to humans will likely employ a vibrating mesh nebulizer (VMN). Compared to the 50-70% lung deposition achieved in adult humans with a VMN, deposition in macaques is <5%, an initial major obstacle to demonstrating protection. Such problems have been partly overcome by using a more efficient modified VMN and proportionally higher doses, which together generate an effective rHuBChE pulmonary bioshield and protect against high levels of inhaled Px.
Topics: Aerosols; Animals; Drug Delivery Systems; Humans; Inhalation Exposure; Lung; Organophosphorus Compounds; Protective Agents
PubMed: 27371808
DOI: 10.1111/nyas.13106