The kinetics of inhibition of Na-K-ATPase activity by o, 0-dimethyl o-(2,2-dichlorovinyl) phosphate(DDVP) was investigated with homogenerate of rabbit cerebral cortex. The results were summarized as the follows : 1. Inhibition of Na-K-ATPase activity by DDVP showed a dose-dependent manner with an estimated I5.0 of 3.5x10(-4) M. 2. Altered pH and activity curves for Na-K-ATPase activity demonstrated comparable inhibition by DDVP in buffered acidic, neutral and alkaline pH renges. 3. Kinetic studies of cationic-substrate activation of Na-K-ATPase showed noncompetitive with respect to substrate and K+ and a mixed type inhibition with respect to Na+. These results suggest that DDVP appeared to exert its effects on Na-K-ATPase activity by interfering with the formation of Na-dependent phosphoenzyme.
Cerebral Cortex* ; Dichlorvos* ; Hydrogen-Ion Concentration ; Kinetics

OBJECTIVETo develop a method for determining the concentration of dichlorvos in serum by gas chromatography and to provide a basis for clinical diagnosis and monitoring of dichlorvos poisoning.

METHODSThe serum (0.5 ml)collected from patients with dichlorvos poisoning was mixed with ethyl acetate (2.0 ml) and underwent shaking/extraction; the obtained liquid was subjected to standing (5 min) and centrifuging (4000 rpm); the obtained supernatant was collected and blow-dried with nitrogen and was then dissolved in ethanol (50 µl); 1.0 µl of the obtained liquid was collected and loaded into a glass-packed column; gas chromatography was performed using a nitrogen-phosphorus detector.

RESULTSA linear relationship was found when the concentration of dichlorvos in serum was 5.0 ∼ 50.0 µg/ml, with a regression equation of y = 804.13x-691.8 (r = 0.9992). The minimum detectable concentration was 2.0 µg/ml, the recovery rate was 86.8% ∼ 94.5%, the relative standard deviation (RSD) was 4.6% ∼ 5.5%, with an intra-day RSD of 4.52% ∼ 5.21% and an inter-day RSD of 3.56% ∼ 5.52%.

CONCLUSIONThis determination method is easy to operate, efficient, and accurate, and can be used for quickly diagnosing dichlorvos poisoning and quantitatively evaluating treatment outcome.

Chromatography, Gas ; methods ; Dichlorvos ; blood ; Humans ; Serum

Dichlorvos ; toxicity ; Disseminated Intravascular Coagulation ; complications ; Humans ; Organophosphate Poisoning ; complications

BACKGROUNDOrganophosphate poisoning is an important health problem in developing countries which causes death mainly by inducing acute lung injury. In this study, we examined the effects of penehyclidine hydrochloride (PHC), a selective M-receptor inhibitor, on dichlorvos-induced acute lung injury in swine.

METHODSTwenty-two female swines were randomly divided into control (n = 5), dichlorvos (n = 6), atropine (n = 6), and PHC (n = 5) groups. Hemodynamic data, extravascular lung water index (EVLWI), and pulmonary vascular permeability index (PVPI) were monitored; blood gas analysis and acetylcholinesterase (AchE) levels were measured. PaO2/FiO2, cardiac index (CI), and pulmonary vascular resistance indices (PVRI) were calculated. At termination of the study, pulmonary tissue was collected for ATPase activity determination and wet to dry weight ratio (W/D) testing 6 hours post-poisoning. TUNEL assay, and Bax, Bcl-2, and caspase-3 expression were applied to pulmonary tissue, and histopathology was observed.

RESULTSAfter poisoning, PHC markedly decreased PVRI, increased CI more effectively than atropine. Anticholinergic treatment reduced W/D, apoptosis index (AI), and mitigated injury to the structure of lung; however, PHC reduced AI and caspase-3 expression and improved Bcl-2/Bax more effectively than atropine. Atropine and PHC improved ATPase activities; a significant difference between groups was observed in Ca(2+)-ATPase activity, but not Na(+)-K(+)-ATPase activity.

CONCLUSIONSThe PHC group showed mild impairment in pathology, less apoptotic cells, and little impact on cardiac function compared with the atropine group in dichlorvos-induced acute lung injury.

Acute Lung Injury ; chemically induced ; drug therapy ; Animals ; Dichlorvos ; toxicity ; Female ; Quinuclidines ; therapeutic use ; Swine

This study was carried out to obtain the basic data for the preverition of chronic poisoning by organic phosphate pesticides. 6 sprayers who participated in the summer pest control programs of Jeonju city were chosen as the subjects in this study. Pesticides which were spread in the period of study are DDVP (1.09%), dursban (1.8%) and dibrom (1.9%). And from May 16, 1983 to Aug. 22, 1983, plasma cholinesterase activity, hematological and biochemical parameters were measured with several physical examinations for each sprayers and controls. Majors findings are as following; 1. Before pesticides were sprayed, plasma cholinesterase were 7.32+/-6 microM/20microliter/hr. in sprayers and 7.13+/-1.39 microM/20 microliter/hr. in the control group(p>0.05). 2. At 60th day of spraying, plasma cholinesterase activity of sprayers was 6.78+/-2.01 microM/20 microliter/hr. Which is significantly decreased from the pre-exposed value(p<0.01), but plasma cholinesterase activity in the control group was not changed. 3. The specific findings which suggested to organophosphorous poisoning were not found through the period of study. 4. Hematological and bichemical parameters were not significantly changed in the both groups.
Chlorpyrifos ; Cholinesterases* ; Dichlorvos ; Jeollabuk-do ; Naled ; Occupations* ; Pest Control ; Pesticides* ; Physical Examination ; Plasma* ; Poisoning

OBJECTIVE: To analyze the density, distribution and insecticide resistance of Aedes albopictus in Ningbo City in 2021, so as to provide insights into formulation of dengue fever control strategies. METHODS: Four administrative villages were randomly selected from each county (district) in Ningbo City from April to November, 2021, to investigate the indoor population density of Aedes larvae, and the Breteau index (BI) was calculated. The population density of adult mosquitoes was investigated in residential areas, parks/bamboo forests, waste tire stacking sites/waste stations/construction sites in each county (district). On June 2021, larvae of the natural strain A. albopictus were collected from epidemic sites of dengue fever in Ningbo City in 2018, and raised in laboratory. Then, larvae and female mosquitoes without blood feeding were selected for insecticide resistance bioassays, while insecticide-sensitive strains of A. albopictus served as controls. The resistance of A. albopictus larvae to deltamethrin, beta-cypermethrin, propoxur, temephos and dichlorvos using the impregnation method, and the medium lethal concentration (LC₅₀) and resistance ratio (RR) were calculated. The resistance of adult A. albopictus to beta-cypermethrin, permethrin, deltamethrin, propoxur and malathion was determined using the tube bioassay, and the mosquito mortality was calculated. RESULTS: A total of 10 072 small water containers from 9 935 households were investigated in Ningbo City in 2021, and there were 1 276 containers with Aedes larvae detected, with an average BI of 12.89. Totally 1 422 mosquito nets were allocated and 954 female A. albopictus were captured, with an average net trapping index of 1.34 mosquitoes/(net·hour). Both larval and adult A. albopictus mosquitoes were found from April to November, and the density of larval A. albopictus peaked in September (BI = 21.21), while the density of adult A. albopictus peaked in August, with a net trapping index of 2.38 mosquitoes/(net·hour). The LC₅₀ values of delta-methrin, beta-cypermethrin, propoxur, temephos and dichlorvos were 0.017 4, 0.000 9, 0.364 1, 0.038 1 mg/L and 0.001 6 mg/L against larvae of natural strains of A. albopicchus, with RRs of 49.66, 25.53, 9.65, 2.24 and 6.06, and the mortality rates of adult mosquitoes were 66.00% (66/100), 69.39% (68/98), 25.00% (25/100), 98.97% (96/97) and 100.00% (98/98) 24 hours post-treatment with 0.08% beta-cypermethrin, 0.03% deltamethrin, 0.4% permethrin, 0.05% propoxur, and 0.5% malathion for 24 h, respectively. CONCLUSIONS A. albopictus is widely distributed in Ningbo City, with a high population density and presents high-level resistance to common pyrethroid insecticides. The population density and insecticide resistance of A. albopictus requires to be reinforced.
Animals ; Female ; Malathion ; Temefos ; Aedes ; Propoxur ; Permethrin ; Dichlorvos ; Mosquito Vectors ; Larva ; Dengue/prevention & control*

Animals ; Chromatography, Thin Layer ; Dichlorvos ; blood ; Dimethoate ; blood ; Insecticides ; blood ; Methyl Parathion ; blood ; Mice ; Organothiophosphorus Compounds ; blood

OBJECTIVETo investigate the diversity of acetylcholinesterase (AChE) activity in variety classes and strains of Culex pipiens pallens and provide a basis for the insecticide-resistance detection of mosquito by biochemical method.

METHODSAChE insensitivity of single mosquito was determined, using acetythiocholine iodide (ATch) as the substrate, 5,5'-dithio-bis (2-nitrobenzoic acid) (DTNB) as the developer, and propoxur as the inhibitor.

RESULTThere were significant differences in AChE activity among the four types of IV instar larvae and 3-day-old adult female of sensitive strain mosquito (P<0.01). The AChE activity of the 3-day-old adult female was higher than that of IV instar larvae of the four types of sensitive strain mosquito (P<0.01). The AChE activity of anti-DDVP (Rd) and anti-propoxur (Rp) strains of Culex pipiens pallens was significantly higher than that of sensitive (S) strain (P<0.01), while the AChE activity of anti-cypermethrin (Rc) strain of Culex pipiens pallens was similar to that of S strain (P>0.05). The individual frequency of insensitive AChE of Rd and Rp strains of Culex pipiens pallens was significantly higher than that of sensitive (S) strain (P<0.01), while the individual frequency of insensitive AChE of Rc strain of Culex pipiens pallens was similar to that of S strain(P>0.05).

CONCLUSIONThe AChE activity determination can be used to examine the insecticide-resistance of mosquito.

Acetylcholinesterase ; metabolism ; Animals ; Culex ; classification ; enzymology ; Dichlorvos ; pharmacology ; Female ; Insecticide Resistance ; Propoxur ; pharmacology ; Pyrethrins ; pharmacology ; Species Specificity

PURPOSE: Organophosphorus (OP) pesticides are differentiated into 3 groups according to their toxicity. The differences in chemical composition of each OP pesticide determines its toxicokinetic characteristics. There are few human studies that address the clinical results of poisoning according to the OP pesticide. In this study, we aimed to examine the differences in clinical features among self-poisoning from 4 highly toxic OP pesticides. METHODS: The 4 kinds of OP poisonings included 17 cases of Dichlorvos, 17 cases of EPN, 17 cases of methidathion, and 13 cases of phosphamidon. We set primary outcomes as GCS, atropine dose required, duration of patient need for atropine, proportion who required ventilation, duration on ventilation, and the interval from ingestion to ventilation. Secondary outcomes were the proportion of OP-induced delayed neuropathy, duration of ICU stay, and proportion who required additional infusion of pralidoxime chloride (PAM). RESULTS: The EPN group required the largest amount of atropine, the longest duration of atropine use, the longest duration for support of mechanical ventilation, and the longest ICU stay. Furthermore the proportion who required additional PAM and neuropathy were in the EPN group. However, the EPN group had the longest interval from ingestion to ventilatory support. Meanwhile, the Dichlorvos group exhibited comparatively mild clinical features. CONCLUSION: Throughout this study, we found different clinical features to each OP pesticide poisoning. It can be explained by differences in chemical composition, which determined the speed of aging, the reactivation rate of OPenzyme, the metabolism, the fat solubility, and other characteristics of the pesticides.
Aging ; Atropine ; Dichlorvos ; Eating ; Humans ; Organophosphorus Compounds ; Organothiophosphorus Compounds ; Pesticides ; Phosphamidon ; Pralidoxime Compounds ; Respiration, Artificial ; Solubility ; Ventilation

OBJECTIVETo study the mechanism of dichlorvos leading to hypospadia of rats.

METHODSFrom the 12th to the 17th day of conception, 20 pregnant female rats (the experiment group) were given 10 mg/(kg x d) dichlorvos, while another 10 (the control group) administered 1.5 ml 0.9% NaCl/day. Out of 88 male newborns of the 20 experimental mother rats, 22 had hypospadia, while out of the 33 male newborns of the 10 controls, none had the problem. Five hypospadia newborns from the experiment group and another 5 normal ones from the control group were raised to sexual maturity, and then their testes were excised and embedded in paraffin, and the tissue sections were analyzed by regular HE staining and SP immunohistochemical staining with Calretinin.

RESULTSHE staining showed that the number of Leydig cells in the testis tissues of the hypospadia rats decreased significantly compared with the normal ones, but no change was observed either in the number or in the morphology of the seminiferous tubules. Moreover, the Calretinin positive Leydig cells were reduced dramatically in the testes of the hypospadia rats.

CONCLUSIONPregnant female rats, when exposed to dichlorvos, may cause reduction of testis Leydig cells in their male offsprings. Thus the probable mechanism of rat hypospadia induced by dichlorvos may lie in the decrease of the testosterone level caused by damage to Leydig cells from dichlorvos toxicity.

Animals ; Cell Count ; Dichlorvos ; toxicity ; Female ; Hypospadias ; chemically induced ; pathology ; Leydig Cells ; pathology ; Male ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Testis ; pathology