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Chemosphere Sep 2017Advanced oxidation processes (AOPs) are utilized due to their ability to treat emerging contaminants with the fast reacting and non-selective hydroxyl radical (OH)....
Advanced oxidation processes (AOPs) are utilized due to their ability to treat emerging contaminants with the fast reacting and non-selective hydroxyl radical (OH). Organophosphorous insecticides are common drinking water contaminants, with 12 different compounds of this class being found on the US EPA's most recent Candidate Contaminant List (CCL4). The use of the AOP UV/HO for the treatment of organophosphorous insecticides was explored in this study, by coupling biological and analytical tools to follow the abatement of the target compounds. Four insecticides were explored for advanced oxidation treatment: acephate, dicrotophos, fenamiphos, and methamidophos. All four compounds were fast reacting with OH, all reacting with second order rate constants ≥5.5 × 10 Ms. Three major endpoints of toxicity were studied: estrogenicity, genotoxicity (mutagenicity) and neurotoxicity. None of the target compounds showed any estrogenic activity, while all compounds showed an active genotoxic (mutagenic) response (AMES II assay) and most compounds had some level of neurotoxic activity. AOP treatment did not induce any estrogenic activity, and reduced the compounds' neurotoxicity and genotoxicity in all but one case. Methamidophos degradation by UV/HO resulted in an increase in genotoxicity, likely due to the formation of toxic transformation products. The increase in toxicity gradually decreased with time, possibly due to hydrolysis of the transformation products formed. This study provides insights into parent compound abatement and the changes in toxicity due to transformation products.
Topics: Hydrogen Peroxide; Hydroxyl Radical; Models, Theoretical; Mutagens; Organophosphorus Compounds; Oxidation-Reduction; Pesticides; Toxicity Tests; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification
PubMed: 28521162
DOI: 10.1016/j.chemosphere.2017.04.150 -
Journal of Economic Entomology Apr 2017Application of insecticides for stink bug management through overhead irrigation, also called chemigation, could reduce application costs, soil compaction, and...
Application of insecticides for stink bug management through overhead irrigation, also called chemigation, could reduce application costs, soil compaction, and applicator exposure, while enabling growers to treat multiple fields simultaneously. The objective of these laboratory experiments was to compare knockdown, survival, and efficacy of insecticides when appropriately diluted for ground sprayer and chemigation applications. Treatments included water, bifenthrin [0.11 kg (AI)/ha] and dicrotophos [0.56 kg (AI)/ha] diluted for a ground sprayer (93.5 liters/ha), bifenthrin and dicrotophos diluted for chemigation (25,396 liters/ha), and bifenthrin and dicrotophos plus adjuvants diluted for ground sprayer or chemigation. Two- to 14-day-old adults of Nezara viridula (L.), Euschistus servus (Say), and Halyomorpha halys (Stål) were briefly submerged in appropriately diluted insecticides and then introduced into a disposable petri dish with or without food. Dishes were placed in a growth chamber provisioned with digital video cameras to monitor knockdown and feeding after insecticide exposure. Knockdown was visually assessed at 24 h after treatment followed by mortality and recovery from knockdown at 48 h after treatment. All stink bugs were knocked down within 1 h and never recovered when exposed at ground sprayer dilutions. However, many bugs survived chemigation dilutions. Less than half of the stink bugs were knocked down when exposed to dicrotophos (with or without adjuvants) and survival ranged from 17 to 77%, compared to 7-90% survival when exposed to bifenthrin at chemigation dilutions. These results strongly suggest that chemigation applications for stink bug management need to be closely examined.
Topics: Animals; Heteroptera; Insect Control; Insecticides; Organophosphorus Compounds; Pyrethrins; Species Specificity
PubMed: 28334122
DOI: 10.1093/jee/tow315 -
Food and Chemical Toxicology : An... May 2017Dicrotophos (Dic), an insecticide and acaricide, is used against a variety of sucking, boring and chewing pests. It was proven that Dic induced oxidative DNA damage in...
Dicrotophos (Dic), an insecticide and acaricide, is used against a variety of sucking, boring and chewing pests. It was proven that Dic induced oxidative DNA damage in HepG2 cells. However, the molecular mechanisms of this compound were still unclear. First of all, the cytotoxicity and oxidative DNA damage were confirmed. Next, using RNA-seq for detecting differential expressed genes (DEGs) in cells treated with 50 μM Dic for 24 h, we showed that the dysregulation of these genes, irrespective of up (1298 genes) or down (2125 genes) regulation, could be attributed to some diverse pathways/metabolisms using KEGG analysis, particularly in DNA damage responses (DDRs) such as oxidative phosphorylation, nucleotide excision repair and cell cycle arrest. Validation of some randomly selected DDR genes confirmed RNA-seq results. We further demonstrated that Dic induced ROS overproduction, the loss of mitochondrial depolarization and cell cycle arrest in the G0/G1 phase. In addition, we also definitely clarified the role of CSA, a nucleotide excision repair enzymes in Dic-treated cells. Collectively, our results showed that various mechanisms of Dic-induced toxicity in HepG2 cells including downregulation of some genes related to nucleotide excision repair including CSA and increased oxidative stress.
Topics: Apoptosis; Autophagy; Cell Cycle Checkpoints; DNA Damage; DNA Repair; DNA Repair Enzymes; Gene Expression Regulation; Hep G2 Cells; Humans; Membrane Potential, Mitochondrial; Organophosphorus Compounds; Oxidative Stress; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; Sequence Analysis, RNA; Transcription Factors
PubMed: 28302478
DOI: 10.1016/j.fct.2017.03.023 -
Current Pharmaceutical Design 2017Reversible cholinesterase inhibitors, when given prophylactically before exposure to organophosphates, are able to decrease organophosphate-induced mortality. However,...
BACKGROUND
Reversible cholinesterase inhibitors, when given prophylactically before exposure to organophosphates, are able to decrease organophosphate-induced mortality. However, the efficacy of pyridostigmine, the only pre-treatment substance approved by the US Federal Drug Administration, is unsatisfactory.
METHODS
In search of a better prophylactic compound, we determined in vivo the protection conferred by five cholinesterase inhibitors (ranitidine, physostigmine, tacrine, K-27 and pyridostigmine), which were administered in equitoxic dosage (1/4 of LD01) 30 minutes before exposure to the organophosphate dicrotophos. Efficacy was measured in rats by Cox analysis calculating the relative risk of death (RR), RR being 1 for the reference group which received dicrotophos and no prophylaxis.
RESULTS
K-27 (RR=0.06), physostigmine (RR=0.15), pyridostigmine (RR=0.22) and tacrine (RR=0.28) significantly (p ≤ 0.05) reduced dicrotophos-induced mortality in comparison to the reference group (dicrotophos without pre-treatment), whereas ranitidine (RR=0.86) had no significant influence. The experimental oxime K-27, when given before dicrotophos exposure, conferred the best in vivo protection. This was significantly (p ≤ 0.05) more efficacious than pre-treatment with any other tested compound. The differences in efficacy between the second best compound, physostigmine, and the less efficacious substances (tacrine and pyridostigmine) were also statistically significant.
CONCLUSION
These data indicate that K-27 can be considered a very efficacious prophylactic agent for organophosphate exposure.
Topics: Animals; Cholinesterase Inhibitors; Female; Humans; Male; Organophosphates; Organophosphorus Compounds; Oximes; Pre-Exposure Prophylaxis; Pyridinium Compounds; Rats; Rats, Wistar; Survival Rate; Treatment Outcome
PubMed: 27799040
DOI: 10.2174/1381612822666161027154303 -
Analytical Chemistry Jul 2016In this proof of concept study, chemical threat agent (CTA) samples were classified to their sources with accuracies of 87-100% by applying a random forest statistical...
Use of Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometric Detection and Random Forest Pattern Recognition Techniques for Classifying Chemical Threat Agents and Detecting Chemical Attribution Signatures.
In this proof of concept study, chemical threat agent (CTA) samples were classified to their sources with accuracies of 87-100% by applying a random forest statistical pattern recognition technique to analytical data acquired by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC × GC-TOFMS). Three organophosphate pesticides, chlorpyrifos, dichlorvos, and dicrotophos, were used as the model CTAs, with data collected for 4-6 sources per CTA and 7-10 replicate analyses per source. The analytical data were also evaluated to determine tentatively identified chemical attribution signatures for the CTAs by comparing samples from different sources according to either the presence/absence of peaks or the relative responses of peaks. These results demonstrate that GC × GC-TOFMS analysis in combination with a random forest technique can be useful in sample classification and signature identification for pesticides. Furthermore, the results suggest that this combination of analytical chemistry and statistical approaches can be applied to forensic analysis of other chemicals for similar purposes.
Topics: Chlorpyrifos; Chromatography, Gas; Dichlorvos; Gas Chromatography-Mass Spectrometry; Models, Statistical; Organophosphorus Compounds; Pesticides
PubMed: 27295356
DOI: 10.1021/acs.analchem.6b00725 -
Chemosphere Sep 2016Insecticide resistance is usually associated with pests, but may also evolve in natural enemies. In this study, adult beetles of three distinct North American...
Insecticide resistance is usually associated with pests, but may also evolve in natural enemies. In this study, adult beetles of three distinct North American populations of Hippodamia convergens Guérin-Méneville, and the progeny of reciprocal crosses between the resistant and most susceptible population, were treated topically with varying concentrations of lambda-cyhalothrin and dicrotophos. In addition, the LD50s of both insecticides were applied in combination to resistant individuals. The developmental and reproductive performance of each population was assessed in the absence of insecticide exposure to compare baseline fitness. California and Kansas populations were susceptible to both materials, whereas Georgia (GA) beetles exhibited a resistance ratio (RR50) of 158 to lambda-cyhalothrin and 530 to dicrotophos. Inheritance of lambda-cyhalothrin resistance was X-linked, whereas inheritance of dicrotophos resistance was autosomal. Mortality of resistant beetles treated with a mixture of LD50s of both materials was twice that of those treated with lambda-cyhalothrin alone, but not significantly different from those receiving dicrotophos alone. Life history parameters were largely similar among populations, except that Georgia beetles had higher egg fertility relative to susceptible populations. We conclude that the high levels of resistance to lambda-cyhalothrin and dicrotophos in Georgia beetles reflect heavy loads of these insecticides in local environments, most likely the large acreage under intensive cotton cultivation.
Topics: Animals; California; Coleoptera; Female; Fertility; Georgia; Insecticide Resistance; Insecticides; Kansas; Male; Nitriles; Organophosphorus Compounds; Pyrethrins
PubMed: 27266835
DOI: 10.1016/j.chemosphere.2016.05.075 -
International Journal of Clinical and... 2015Organophosphorus compound poisoning (OPC) is a global issue. The problem is aggravated with the threats of terrorist use, unintentional use and irresponsible practice as...
Organophosphorus compound poisoning (OPC) is a global issue. The problem is aggravated with the threats of terrorist use, unintentional use and irresponsible practice as happened recently in turmoil countries. The purpose of the current study was to investigate the old-generation antihistamine promethazine (PROM), a drug with multi pharmacological actions, as an antidote to extremely and highly toxic (WHO's class IA and IB) OPC poisoning in experimental animal models conducted on adult male wistar rats. Experimental groups were treated intraperitoneal (i.p.) with LD70 of methyl paraoxon (MPOX), class IA and dicrotophos (DCP), class IB alone and a combination of simultaneously i.p. injection of PROM. Mortality was recorded at 30 minutes, 1, 2, 3, 4, 24, 48 hours post injections. RBC-AChE was measured in survivals. MPOX was chosen for further studies with atropine (ATR) and pralidoxime (PAM). In addition to Kaplan-Meir survival analysis, serum lactate dehydrogenase (LDH) and creatinine kinase (CK) from serum were measured in all experimental groups with MPOX. The results revealed significant protection by PROM in both MPOX and DCP intoxicated rats, though the inhibition of RBC-AChE was high. The observed results show that groups treated with a combination of MPOX and PROM or MPOX, PROM, and PAM were protected higher than those treated with MPOX and ATR or MPOX, ATR, and PAM though statistically not significantly different (P ≤ 0.05). No effect was observed on the activity of LDH and CK. The study concludes that PROM may be effectively used in OPC poisoning. However, risk/benefits trials and further studies with different doses and other OPC groups are warranted.
PubMed: 26770383
DOI: No ID Found -
Journal of Separation Science Mar 2016A new mesoporous silica based on the sol-gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS...
A new mesoporous silica based on the sol-gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS in the presence of ammonium solution as catalyst and methanol as solvent. It was used as a solid-phase extraction sorbent for the simultaneous extraction of three organophosphorus pesticides, namely, polar dicrotophos and non-polar diazinon and chlorpyrifos. Analysis was performed using high-performance liquid chromatography with UV detection. CNPrTEOS was characterized by FTIR spectroscopy, field-emission scanning electron microscopy and nitrogen gas adsorption. The surface area and average pore diameter of the optimum sol-gel CNPrTEOS are 379 m(2) /g and 4.7 nm (mesoporous), respectively. The proposed solid-phase extraction based on CNPrTEOS exhibited good linearity in the range of 0.8-100 μg/L, satisfactory precision (1.15-3.82%), high enrichment factor (800) and low limit of detection (0.072-0.091 μg/L). The limits of detection obtained using the proposed solid-phase extraction method are well below the maximum residue limit set by European Union and are also lower (13.6-48.5×) than that obtained by using a commercial CN-SPE cartridge (0.98-4.41 μg/L). The new mesoporous sol-gel CNPrTEOS showed promising alternative as SPE sorbent material for the simultaneous extraction of polar and non-polar organophosphorus pesticides.
PubMed: 26768840
DOI: 10.1002/jssc.201500896 -
Protein and Peptide Letters 2015Organophosphorus (OP) pesticides and nerve agents have been designed to inhibit the hydrolysis of the neurotransmitter acetylcholine by covalently binding to the active...
Organophosphorus (OP) pesticides and nerve agents have been designed to inhibit the hydrolysis of the neurotransmitter acetylcholine by covalently binding to the active site serine of acetylcholinesterase while Alzheimer drugs and prophylactics, such as tacrine, are characterized by reversible binding. Historically, the guinea pig has been believed to be the best non-primate model for OP toxicology and medical countermeasure development because, similarly to humans, guinea pigs have low amounts of circulating OP metabolizing carboxylesterase. To explore the hypothesis that guinea pigs are the appropriate responder species for OP toxicology and medical countermeasure development, guinea pig acetylcholinesterase (gpAChE) was cloned into pENTR/D-TOPO, recombined into pT-Rex-DEST30 and expressed in Human Embryonic Kidney 293 cells. Recombinant gpAChE was purified to a specific activity of 800 U/mg using size exclusion and immobilized nickel affinity chromatography, with purity confirmed by gel electrophoresis. Ellman's assay was used to enzymatically characterize gpAChE, identifying a K(M) of 154±18.7 µmol L(-1) and a k(cat) of 4.79x10(4)±5.26x10(2) /sec. Apparent gpAChE IC50's for diisopropylfluorophosphate, dicrotophos, paraoxon, and an Alzheimer's drug, tacrine, were found to be 10.1±1.98, 337±108, 1.02±0.29 and 0.30±0.01 µmol L(-1), respectively. Apparent gpAChE inhibition constants for diisopropylfluorophosphate, dicrotophos, paraoxon, and tacrine were found to be 8.40±0.60, 4.50±0.30, 0.29±0.01 and 0.42±0.07 µmol L(-1), respectively. Lineweaver-Burk plots confirmed tacrine as a mixed inhibitor and paraoxon, dicrotophos and diisopropylfluorophosphate as irreversible non-competitive inhibitors. gpAChE bimolecular rate constants for diisopropylfluorophosphate, dicrotophos and paraoxon were found to be 1.44±0.33x10(4), 1.56±0.12x10(3) and 4.57± 0.23x10(5) L µmol(-1) min(-1), respectively. Although the blood levels of OP metabolizing carboxylesterases in the guinea pig are similar to the low levels in human blood, the gpAChE is different in its enzymology. Therefore, medical countermeasures against OP intoxication should be tested for efficacy with the recombinant form of gpAChE prior to initiating animal studies.
Topics: Acetylcholinesterase; Animals; Cholinesterase Inhibitors; Guinea Pigs; Humans; Organophosphorus Compounds; Recombinant Proteins
PubMed: 26216268
DOI: 10.2174/0929866522666150728114754 -
Environmental Science and Pollution... Jan 2015Profenofos (PF) is one of the heavily used organophosphorus pesticides (OPPs) of which its contamination is ubiquitous in an agricultural area. This study aims to...
Profenofos (PF) is one of the heavily used organophosphorus pesticides (OPPs) of which its contamination is ubiquitous in an agricultural area. This study aims to acquire and characterize PF-degrading bacterial cultures from contaminated soil. OPP degradation by the novel isolates was then investigated. The experiment was performed at the initial PF concentration of 20 mg/L. The result showed that the enriched consortium comprised three predominant PF-degrading strains designated as PF1, PF2, and PF3. The isolates (PF1, PF2, and PF3) were characterized as Pseudomonas plecoglossicida, Pseudomonas aeruginosa, and P. aeruginosa, respectively. A consortium and all isolates could utilize PF as a sole carbon source with PF removal of more than 90% via a hydrolysis process. The bacterial growth and PF degradation rates followed the first-order kinetic reaction with the rates of 0.4 to 2.7/h and 0.15 to 1.96/h, respectively. Additional carbon supplement deteriorated PF biodegradation. The enriched cultures were also capable for degrading chlorpyrifos and dicrotophos pesticides (33-73% removal). The results indicated that the consortium and isolates are efficient for PF and other OPP degradation and have potential for PF remediation.
Topics: Agriculture; Biodegradation, Environmental; Capsicum; Chlorpyrifos; Insecticides; Microbial Consortia; Organophosphorus Compounds; Organothiophosphates; Pseudomonas; Soil Microbiology; Soil Pollutants
PubMed: 25065481
DOI: 10.1007/s11356-014-3354-1