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Os pesticidas são compostos amplamente utilizados na agricultura, por causa do aumento da eficiência produtiva, no entanto esses compostos tóxicos podem exercer efeitos negativos ao meio ambiente e à saúde humana. O objetivo deste trabalho foi analisar a exposição ocupacional de trabalhadores ruraisa agrotóxicos, através de um estudo descritivo-analítico com abordagem transversal e quantitativa. A amostra foi composta de 63 trabalhadores agrícolas. A caracterização do perfil socioeconômico, o manejo de pesticidas e as condições de saúde foram realizados por meio de entrevistas. Após a coleta das amostrasbiológicas, a atividade da enzima acetilcolinesterase eritrocitária foi avaliada em dois momentos: pré e pós-exposição a pesticidas em um ciclo de plantio e colheita. A idade média dos trabalhadores rurais foi de 48,1 ± 7,6 anos. Eles relataram usar equipamentos de proteção individual, embora de forma incompleta ouinadequadamente, e 46% relataram intoxicação por agrotóxicos. Transtornos do humor como ansiedade (50,3%) e estado depressivo (27,0%) também foram relatados pelos trabalhadores. Houve uma diminuição significativa na atividade da enzima acetilcolinesterase eritrocitária de 0,83 ± 0,06 delta pH/hora para0,71 ± 0,11 delta pH/hora (p < 0,05). A comparação individual dos valores da atividade enzimática mostrou que 19,6% dos trabalhadores estavam intoxicados com carbamatos e organofosforados. A contaminação é atribuída ao manejo inadequado de pesticidas. Considera-se urgente a adoção de medidas paraminimizar intoxicações e outros efeitos nocivos à saúde dos trabalhadores rurais. Pesticides are compounds widely used in agriculture, due the productive efficiency increase. However, these toxic compounds can exert negative effects to environment and human health. This work aim was analyzing the occupational exposure of rural workers to pesticides, through a descriptive-analytical study with cross-sectional and quantitative approach. The sample consisted of 63 farmworkers. Socioeconomic profile characterization, pesticide management, andhealth conditions was carried out through interviews. After biological samples collection, erythrocyte acetylcholinesterase enzyme activity was assessed in two moments: pre- and post-exposure to pesticides in one of planting and harvesting cycle. Rural workers age mean was 48.1±7.6 years. They reported using personal protective equipment, although incompletely or inadequately, and 46% reported pesticide poisoning. Mood disorders such as anxiety (50.3%) and depressive state (27.0%) were also reported by workers. There was a significant decrease in the activity of the erythrocyte acetylcholinesterase enzyme from 0.83±0.06delta pH/hour to 0.71±0.11 delta pH/hour (p < 0.05). Individual comparison of enzyme activity values showed that 19.6% of the workers were intoxicated with carbamate and organophosphate. Contamination is attributed to the inadequate management of pesticides. Adopting measures to minimize intoxications and other harmful effects on the health of rural workers is considered urgent.

Cumulative assessment groups of pesticides have been established for five effects on the nervous system: brain and/or erythrocyte acetylcholinesterase inhibition, functional alterations of the motor, sensory and autonomic divisions, and histological neuropathological changes in neural tissue. Sources of uncertainties resulting from the methodological approach and from the limitations in available data and scientific knowledge have been identified and considered. This report supports the publication of a scientific report on cumulative risk assessment to pesticides affecting the nervous system, in which all uncertainties identified for either the exposure assessment or the establishment of the cumulative assessment groups are incorporated into a consolidated risk characterisation., This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1702/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1708/full This publication is linked to the following EFSA Journal articles: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2019.5764/full

O objetivo do presente estudo foi caracterizar indivíduos do meio rural, diagnosticados com câncer, quanto às práticas no uso de agrotóxicos, sintomas físicos, emocionais, de intoxicação e níveis de acetilcolinesterase eritrocitária. Trata-se de pesquisa transversal, quantitativa, descritiva, em hospital geral, com 92 pacientes oncológicos e agricultores. O projeto foi aprovado pelo CEP sob o número 2.626.873. Instrumento de coleta de dados com variáveis sociodemográficas, práticas no manuseio de agrotóxicos e mensuração da acetilcolinesterase eritrocitária. A análise dos dados com programa Statistical Package for Social Science, estatística descritiva e analítica. Os resultados demonstraram que a maioria do sexo masculino, idoso, baixa escolaridade. Predominam pequenas propriedades rurais, cultivo de hortifrutigranjeiros. 63% expostos ocupacionalmente a agrotóxicos; para proteção, 56,8% usam botas, “sempre”. Orientação técnica insuficiente. Baixa frequência de intoxicação. Menor média de acetilcolinesterase eritrocitária no grupo exposto a agrotóxicos ativo, estatisticamente significativa. Evidenciou-se o predomínio de agricultura familiar, com produção de hortifrutigranjeiros e uso de equipamentos que favorecem o contato direto com agrotóxicos, inclusive uso inadequado de EPIs. Lacunas quanto ao uso seguro destes produtos, provavelmente relacionada à escolaridade, os tornam suscetíveis a agravos da exposição direta e indireta. Mensuração da acetilcolinesterase eritrocitária mostrou valores médios normais e requer exames complementares e monitoramento contínuo. Resultados remetem à ações e intervenções educacionais com vistas à prevenção de agravos e redução dos índices crescentes de câncer nesta população.

Langmuir films prepared from bovine erythrocyte membranes (LFBEM) were studied and transferred to alkylated glasses (Langmuir-Blodgett films, LBBEM) in order to assess the effects of membrane molecular packing on Bovine Erythrocyte Acetylcholinesterase (BEA) catalytic activity. Surface pressure (π) vs Area isotherms showed three 2D-transitions at ~7, ~18 and ~44 mN/m and a collapse pressure at πc = .49 mN/m. The 0?12?0 mN/m compression-decompression cycles resulted reversible while those 0?40?0 mN/m exhibited a significant hysteresis. Taken together, EFM, BAM and AFM images and the stability of the film after 3C-D cycles, we can suggest that over the air-water interface as well as over the silanized glass substrate the surface is mostly covered by a monolayer with a few particles dispersed. Acetylthiocholine hydrolysis was assayed with BEA in bovine erythrocyte membrane suspensions (SBEM) and in LBBEM packed at 10 (LBBEM,10) and 35 mN/m (LBBEM,35), which gave the following kinetic parameters: Vmax = .3.41 ± 0.15, 0.021 ± 0.002 and 0.030 ± 0.003 nmol.min− 1·μg prot− 1 and KM = .0.11 ± 0.02, 0.047 ± 0.017 and 0.026 ± 0.017 mM, respectively. Although from SBEM to LBBEM we lost active enzyme, the catalytic efficiency (Vmax/KM) increased ~750 times. Eugenol and 1,8-cineol inhibited BEA catalytic activity in LBBEM,35. Our results demonstrate the transmission of information between the membrane and the environment within the subphase immediately below the membrane, where anchored proteins are hosted. This was reflected by the membrane packing-induced modulation of BEA catalytic activity. Furthermore, LBBEM provides a proof of concept for the development of biosensors to screen new green pesticides acting through BEA interaction. Fil: Felsztyna, Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina Fil: Turina, Anahi del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina Fil: Perillo, Maria Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina Fil: Clop, Eduardo Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina

N-Aroyl-α-aminoacrylic acid 2-(dialkylamino)alkylamides and their quaternary ammonium salts were synthesized and their physicochemical properties were determined. Results obtained from studies of their interactions with human erythrocyte acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE) are presented. IC50 values (concentrations producing 50% inhibition of the rate of cholinesterase hydrolysis of 0.1 mM acetylthiocholine) were determined for all the compounds synthesized. The results show that all the compounds synthesized had anticholinesterase properties, mainly specific in relation to BChE. Data on the antibacterial properties of the synthesized compounds are also presented.

Осуществлен синтез и описаны физико-химические характеристики 2-(диалкиламино)алкиламидов N-ароил-α-аминоакриловой кислоты и их четвертичных аммониевых солей. Приведены результаты изучения их взаимодействия с эритроцитарной ацетилхолинэстеразой (АХЭ) и плазменной бутирилхолинэстеразой (БуХЭ) человека. Для всех синтезированных соединений определены значения ИК50 (ингибирующая концентрация исследуемого соединения, при которой наблюдается 50 % торможение скорости холинэстеразного гидролиза 0,1 мМ ацетилтиохолина). Согласно полученным данным все синтезированные вещества проявляют антихолинэстеразные свойства и, в основном, специфичны по отношению к БуХЭ. Приведены также данные антибактериальных свойств синтезированных соединений.

A series of O-carbamoylated 1,1,1,3,3,3-hexafluoroisopropanols of general formula RNHC(O)OCH(CF3)2, where R = CH3, n-C3H7, tert-C4H9, cyclo-C6H11, C6H5–CH2, C6H5, 4-Cl-C6H4, 3-Cl-C6H4, 3,4-Cl2-C6H3, and naphthylen-2-yl were synthesized. The reaction kinetics of the synthesized carbamates with human erythrocyte acetylcholinesterase (EC 3.1.1.7), horse serum butyrylcholinesterase (EC 3.1.1.8), and porcine liver carboxylesterase (EC 3.1.1.1) were studied. It was shown that the synthesized carbamates did not inhibit acetylcholinesterase, inhibited weakly butyrylcholinesterase, and inhibited selectively the activity of carboxylesterase. A new selective irreversible inhibitor of carboxylesterase, 2,2,2-trifluoro-1-trifluoromethylethyl cyclohexylcarbamate, which had low acute toxicity, was obtained.

Eight newly synthesized carbacylamidophosphates with the general formula RC(O)NHP(O)Cl2 with R = pCl-C6H4 1a, pBr-C6H4 2a, C6H5 3a, and pMe-C6H4 4a and RC(O)NHP(O)(NC4H8O)2 R = pCl-C6H4 1b, pBr-C6H4 2b, C6H5 3b, pMe-C6H4 4b, were selected to compare the inhibition kinetic parameters, IC50, Ki, kp and KD, on human erythrocyte acetylcholinesterase (hAChE) and bovine serum butyrylcholinesterase (BuChE), Also, the in vivo inhibition potency of compound 2a, 2b and 3a, were studied. The data demonstrates that compound 2a and compound 2b are the potent sensitive as AChE and BuChE inhibitors respectively, and the inhibition of hAChE is about 10-fold greater than that of BuChE.

The inhibition of erythrocyte acetylcholinesterase activity following intravenous, intraperitoneal, subcutaneous, or percutaneous administration of sublethal doses of soman in guinea-pig has been investigated. The inhibition was found to be almost completed within 1 min., 20 min., 60 min. or 90–120 min. respectively, the inhibition rates were of first order, and half-lives were dose dependent. The possibility of storage of soman after administration of sublethal doses was also examined by the injection of electric eel acetylcholinesterase. It is concluded that there is very little, if any, storage of free soman in the organism after injection of sublethal doses of soman.

Erythrocyte acetylcholinesterase (AChE) is bound to the membrane by a complex glycosylphosphatidylinositol anchor, so the effect of alcohol on AChE activity may reflect direct and/or membrane-mediated effects. The indication of a direct interaction between n-butanol and AChE molecules is the activation/inhibition of AChE by occupation of the enzyme's active and/or regulatory sites by alcohol. The activation of AChE can occur only at low concentrations of alcohols, while at high concentrations AChE is inhibited. In this work the mechanism of inhibition of erythrocyte AChE by n-butanol at high concentrations was studied. The values of activity, calculated assuming parabolic competitive inhibition, which implies that one or two molecules of inhibitor bind to the enzyme, fit well to the experimental values. From the values of the inhibition constants it was concluded that at high n-butanol concentrations two alcohol molecules usually interact with AChE.

The effect of pretreatment with equine butyrylcholinesterase (EqBuChE) on cholinesterase inhibition in the blood and brain of rats following inhalation intoxication with low concentrations (1.25 microg/L for 60 min) of sarin were studied. Animals pretreated with different doses of equine butyrylcholinesterase showed significant increases in plasma butyrylcholinesterase activity. However, erythrocyte acetylcholinesterase activity was unchanged. The decrease in acetylcholinesterase and butyrylcholinesterase activity after inhalation intoxication was dependent on the dose of equine butyrylcholinesterase used for pretreatment and was always greater for erythrocyte acetylcholinesterase. Acetylcholinesterase activity in different brain regions was unchanged following pretreatment with equine butyrylcholinesterase. After inhalation exposure to sarin, acetylcholinesterase activity was diminished markedly in the pontomedullar area (51.5% of normal activity) and frontal cortex (72.0% of normal activity), and slightly in basal ganglia (91.4% of normal activity). Plasma levels of sarin were determined using fluoride-induced reactivation of inhibited enzyme. As expected, the amounts of sarin in plasma were almost identical in rats pretreated with EqBuChE as well as in untreated rats. In pretreated animals, the plasma amount of sarin did not depend on the dose of equine butyrylcholinesterase used for pretreatment. Our results demonstrate that equine butyrylcholinesterase pretreatment can be considered as an effective prophylaxis against nerve agents (at least with sarin) and seems to be an alternative or superior to prophylaxis provided by reversible cholinesterase inhibitors.

Objective: To assess the degree of poisoning in farmers using the erythrocyte acetylcholinesterase (AChE) test before and after the exposure to pesticides in townships in central Benin (Glazoué and Savè) and to identify the associated risk factors. Methods: Using a cross-sectional study design, we recruited 264 farm pesticide sprayers, who have been working for at least 5 years. They completed a questionnaire and underwent the AChE test using the Test-mate Model 400 device (EQM Research Inc.) with a photometric sensor, based on the works of Ellman. Results: Organophosphate/pyrethroids were the most common pesticides used by at least 72.96% of the farmworkers. We observed an inhibition of AChE between pre-exposure and post-exposure ( P = .002) for 60.61% of the farmworkers. Among them, 11.88% displayed more than 20% AChE inhibition. Conclusions: Pesticide poisoning is a reality, and AChE monitoring is urgently needed for farmworker surveillance.

Plasma cholinesterase and erythrocyte acetylcholinesterase activities have a long history of use in monitoring both workers at risk of organophosphorus pesticide (OP) exposure and in investigating accidental exposures to OPs. On account of wide inter-individual variation, the establishment of unexposed, baseline enzyme activities is necessary for accurate interpretation. This paper describes the rate of recovery of the two enzymes' activity after substantial over-exposure of eight subjects to the OP dichlorvos. Plasma cholinesterase activity, immediately after exposure, was substantially more inhibited than erythrocyte acetylcholinesterase activity. The plasma enzyme activity showed an exponential pattern of recovery with a half-life of around 12 days, so recovery was essentially complete after about 50 days. This reported half-life of recovery is consistent with the reported de novo synthesis rate of plasma cholinesterase. The mean recovery of erythrocyte acetylcholinesterase activity appeared linear over time, attaining unexposed activity after about 82 days, which is somewhat shorter than the life-span of erythrocytes. These indicate the sort of time period, after an OP incident, before a valid unexposed level can be established in an individual; and substantiate the guidance given in the Health & Safety Executive's document MS17 on a minimum period of 60 days without exposure in order to establish pre-exposure baseline levels.

Kinetic analysis of the interaction of malathion with camel erythrocyte acetylcholinesterase was investigated in the present study. The Michaelis-Menten constant (K(m)) for the hydrolysis of acetylthiocholine iodide (ASCh) was found to be 53.15 microM and the Vmax was 0.287 mumol/min/mg protein. The Kmapp and Vmaxapp were both decreased by increased malathion concentration. Dixon as well as Lineweaver-Burk plots and their secondary replots indicated that the nature of the inhibition was of the pure uncompetitive type with Ki value estimated as 102.1 ppm. The Kiapp decreased while Vmaxiapp increased by an increased concentration in ASCh.

A rapid and sensitive in vivo method for the evaluation of skin decontaminant efficacy following percutaneous exposure to organophosphonates (OPs) was developed using erythrocyte acetylcholinesterase (AChE; EC 3.1.1.7) inhibition in the rabbit as an end point. The level of AChE inhibition was evaluated for use as a more humane means of assessing skin decontaminant efficacy than lethality-based methods. Groups of anesthetized animals were exposed percutaneously to either of two highly toxic OPs [thickened soman (TGD) or VX], and 2 min later were treated with a known effective skin decontaminant or were untreated (negative control). Blood samples were drawn and assayed for AChE activity 5 min before TGD or VX exposure and at 30, 60, and 120 min after exposure. Percent AChE inhibition relative to preexposure levels was calculated at each postexposure time for each animal in control and treatment groups. Efficacy data based on percent AChE inhibition were compared with results from previous efficacy studies p...

Le dosage de l’acétylcholinestérase dans les érythrocytes est un bon indicateur d’exposition professionnelle aux organophosphorés et aux carbamates. L’étude a porté sur 103 personnes consentantes, dont 91% de sexe masculin avec un âge moyen de 43 ± 16 ans et un poids corporel de 65 ± 17 kg ; et 9% de sexe féminin avec un âge moyen 38 ± 15 ans et un poids corporel de 67 ± 21 kg. Toutes ces personnes sont impliquées dans la campagne 2006 de traitements phytosanitaires dans 4 des régions du Niger où le problème des acridiens se pose avec plus d’acuité. L’analyse clinique somatique et les enquêtes anamnestiques effectuées sur les participants à cette étude, n’ont révélé ni d’antécédents cliniques graves, ni de cas empoisonnements aux pesticides. Le dosage de l’acétylcholinestérase érythrocytaire a été réalisé à la température ambiante de laboratoire (25°C) à l’aide de l’appareil Test Mate® model 400, méthode spectrophotométrique. La cholinestérasémie moyenne de pré-exposition des 103 personnes est de 3,63 ± 0,61 U/ml, celle des sujets masculins est de 3,57 ± 0,53 U/ml et celle des sujets féminins est de 3,48 ± 0,44 U/ml, cette différence n’est pas significative. Après l’exposition aux organophosphorés, une légère baisse de la cholinestérasémie des 103 personnes a été observée par rapport à leur valeur de pré-exposition, elle est de 3,21 ± 0,17 U/ml ; celle des personnes de sexe féminin est de 3,48 ± 0,44 U/ml et celle des personnes de sexe masculin est de 3,57 ± U/ml. Dix sept personnes (16,50%) sur 103 présentent une hypocholinestérasémie, puisque leur taux d’inhibition varie de 31% à 36%. Parmi ces 17 personnes, 9 (53%) ont un taux d’inhibition supérieur à 40% par rapport à leur valeur de référence. Aucun cas de syndrome cholinergique n’a été décelé parmi les 17 personnes dont le taux d’inhibition le seuil de 30% tel que recommandé par l’Organisation mondiale de santé., The amount of the erythrocyte acetylcholinesterase is a good indicator of professional exposure to organophosphorus and carbamates pesticides. The study related to 103 agreeing people, including 91% of men with an age of 43 ± 16 years and a body weight of 65 ± 17 kg; and 9% of women with an age 38 ± 15 years and a body weight of 67 ± 21 kg. All these people are implied in pesticide application in year 2006 in 4 of the countries of Niger where the problem of the acridians arises with more acuity. The clinical examination and the anamnestic investigations carried out into the participants in this study, revealed neither of serious clinical antecedents, nor of case poisonings to the pesticides. The Test-Mate ChE, based on a photometric system, was used to measure the acetylcholinesterase activities in the erythrocytes after an exposure to these pesticides. The average cholinesterasemy of pre-exposure of the 103 people is of 3.63 ± 0.61 U/ml, with 3.57 ± 0.53 U/ml for the men and 3.48 ± 0.44 U/ml for the women, this difference is not significant. After the exposure to organophosphorus, a low reduction of the cholinesterasemy of the 103 people was observed compared to their pre-exposure (baseline) measurements of AChE, it was of 3.21 ± 0.17 U/ml; with 3.48 ± 0.44 U/ml for the women and 3.57 ± 0.53 U/ml for the men. Seventeen people (16.50%) of 103 showed a hypocholinesterasemy, because their inhibition rate varied from 31% to 36%. The reduction of the enzymatic activity in the bodies of some of the applicators (9 people) largely exceeded the biological threshold recommended by the World Health Organization which is 30%, but no cholinergic syndrome was detected.

A number of lupinine esters of carboxylic acids and their hydrochlorides and methiodides have been synthesized. It has been shown that these compounds are reversible inhibitors of human blood erythrocyte acetylcholinesterase and horse blood serum butyryl cholinesterase. Noncompetitive inhibitors of these enzymes have been found among the compounds synthesized.

Dose-effect and dose-response relationships in occupational neurotoxicology are rarely studied by means of biochemical methods. In order to investigate the potential neurotoxic effects of lead during occupational exposure to this metal, the activity of erythrocyte acetylcholinesterase (AcChE), as well as blood pressure and pulse, were determined in various artisans in Abeokuta, Nigeria, who have been shown to be occupationally exposed to lead, and these were related to blood lead levels. AcChE activity in the artisans was inhibited to varying extents. While AcChE activity was inhibited to the tune of 39% in the male petrol station attendants, the inhibition amounted to 32% in female petrol station attendants. In other artisans, AcChE inhibition ranged from 31% in the welders to 38% in painters. The lowest inhibition of 15% was obtained in the panel beaters. Correlations, as calculated by Pearson's method, revealed a significant (p0.001) inverse linear relationship between AcChE activity and blood lead levels (r=-0.40; y=-120.38x+13935.59; p0.001). Blood pressure and pulse were not significantly different between control and lead-exposed subjects. Our findings suggest that erythrocyte AcChE activity could be used as a biomarker of lead-induced neurotoxicity in occupationally exposed subjects.

Twelve 1- N -substituted thiocarbamoyl-3-phenyl-5-thienyl-2-pyrazoline derivatives were synthesized and their biological interactions with human plasma and erythrocyte acetylcholinesterase (AChE) and butrylcholinesterase (BuChE) enzymes were assessed. Compounds 3i – 3l of newly synthesized N -substituted pyrazolines, which were presented as selective and irreversible MAO-B inhibitors in our previous report, were found to inhibit human erythrocyte and plasma AChE activities selectively and non-competitively suggesting that these compounds may interact with a region close to the peripheral site of the enzyme molecule which could shift the proper positioning of the catalytic center. Compounds 3e – 3h inhibited both AChE and BuChE activities of human erythrocytes, but the inhibitory potencies of these compounds towards BuChE were found to be higher than that of towards AChE. Inhibition was found to be non-competetive and reversible. These data suggested that newly synthesized N -substituted pyrazoline derivatives can be evaluated as both MAO-B and cholinesterase inhibitors which may have promising features in the treatment of Alzheimer's and Parkinson's diseases.

Until now the efficacy of new antidotes against organophosphorus poisoning has been primarily evaluated in animal models. However, the transmission of these results to humans is hampered by species differences. Besides atropine, oximes are considered as main antidotes. The most important effect of these compounds is the reactivation of inhibited acetylcholinesterase (AChE). The reactivating potency of oximes can be investigated with human material in vitro and was evaluated in the present study with human erythrocyte AChE after inhibition by different nerve agents and pesticides.

© 1998 – IOS Press. All rights reserved, Sodium fluorescein angiography is a widely used routine ophthalmological diagnostic procedure which enables the study of chorioretinal microcirculation and consists of the injection of sodium fluorescein into the systemic bloodstream. The aim of the present study was to evaluate whether or not fluorescein interferes with erythrocyte properties during the angiographic procedure. In a group of 37 patients, 26 with non-insulin-dependent diabetes mellitus (DM) with and without retinopathy, and 11 without diabetes mellitus (non-DM) although affected by other ophthalmological diseases, all undergoing routine angiography, blood samples were drawn before (T0) and 30 min (T30) after fluorescein injection. The erythrocyte aggregation index (EAI), membrane lipid fluidity and erythrocyte acetylcholinesterase activity were determined in both groups. After fluorescein injection there was no statistical change in EAI and erythrocyte membrane fluidity in either group. Erythrocyte acetylcholinesterase activity, a marker of membrane protein integrity, decreased significantly (p < 0:01) in the DM group. Membrane lipid fluidity did not change with fluorescein injection, however, (i) in the DM group erythrocyte membranes became more rigid than in the non-DM (DPH: p < 0:01); (ii) EAI and membrane lipid fluidity became significantly correlated (r = 0:6263, p < 0:05) in non-DM patients at T30. In conclusion, fluorescein administration for angiographic procedures seems to interact with erythrocyte membrane, namely, in diabetic patients, which may interfere with the blood flow in the microcirculation.

In this study we have examined 532 migrant farm workers engaged mainly in thecultivation of vegetable crops, in both greenhouses and openfarms, and an equalnumber of controls. Erythrocyte acetylcholinesterase activity (AChE) was measuredto determine the degree of toxicity due to exposure to organophosphate andcarbamate pesticides in the farm workers employed either as foremen (41.5%) orfarmers (58.5%). The mean ages of the farm workers and controls were 35.2 ±7.4(mean ± SD) years and 34 6 ± 7.1 years. AChE activity of the farm workers andcontrols was 3.89 ±0.64 Ul/ml (mean±SD) and 4.15 ±0 29 Ul/ml. The haemoglobinadjusted erythrocyte cholinesterase activity (HAChE) was 29.96 ± 4.14(mean ± SD) forfarm workers and 32 10 ±2 26 for controls. AChE activity was very highly significantlylower for the foremen (3 76 ± 0 69) compared to farmers (3 98 ± 0.59) (Student's f-test= 4.13, p = 0.0001). HAChE was also very highly significantly lower for foremen (29.24±4.37) compared to farmers (30.46 ±3.88) (Student's f-test = 3 64, p = 0.0001). Thepoorly controlled use of pesticides in the farms appeared to have caused sub-clinicalintoxication in the farm workers and indicated the need for training and implementationof hygiene practices.Key words: Agricultural workers; carbamates; erythrocyte acetylcholinesterase; farm workers;greenhouses; haemoglobin, haemoglobin adjusted erythrocyte cholinesterase, openfarms,organophosphates; pesticides

Dermal absorption has long been recognized as a major route of exposure to organophosphate pesticides. Measurements after actual usage have been made using patch tests, hand rinses, and fluorescent visualization. Depression of erythrocyte acetylcholinesterase (ACHE) has been reported in relation to oral doses of various pesticides, including ethyland methyl-parathion (Rider and Puletti 1969; Rider et al. 1970; Rider et al. 1971). Dermal doses have also been measured in relation to erythrocyte AChE depression in a few studies (Spear et al. 1977, Hayes et al. 1964, Hussain et al. 1990). One study found an average 10% depression of erythroeyte AChE (although not clinically abnormal) with an average dermal deposition during the workday of 5.5 mg methyl-parathion (Ware et al. 1975).

Previous studies on the spontaneous reactivation of phosphorylated and phosphonylated cholinesterases report bell-shaped curves with reaction rate maxima between pH values of 7 and 9. By way of contrast, we found reactivation rate minima in the same pH region for a phosphinylated bovine erythrocyte acetylcholinesterase and three phosphinylated eel acetylcholinesterases. To further elucidate these observations, eel acetylcholinesterase was inhibited with racemic 4-nitrophenyl ethyl(phenyl) phosphinate. The spontaneous reactivation of the inhibited enzyme over the pH range 6.00 to 9.00 was monitored following 1 . both inhibition and spontaneous reactivation at the same pH, and 2 . inhibition at pH 7.60 followed by spontaneous reactivation at the selected pH. The combined plots of both studies gave overlapping pH curves with minima around pH 7.60. The results indicate that the minima in the rates of the spontaneous reactivation of phosphinylated acetylcholinesterases are not the consequence of a pH-controlled change in the relative inhibition rates of the P(+)- and P(−)-enantiomers participating in the inhibition reaction. Our results suggest that the orientation of the phosphinyl group in the active site of phosphinylated acetylcholinesterase is quite different from that of the inhibitor groups in phosphonylated or phosphorylated enzyme.

Hirschsprung's disease is a relatively prevalent disorder in newborn babies and young children. Acetylcholinesterase (AChE) activity is augmented locally, in the neural plexus of the affected gut segment. It has been suggested that this enzyme will also be increased in red blood cells (RBCs) of affected children. Thus, we studied AChE activity in newborn babies and children, as well as age-adjusted data. This Israeli study consisted of healthy and affected Bedouins as well as Ashkenazi and Sephardic Jews. This study supports the Japanese study in that the RBC AChE is not augmented in Hirschsprung's disease. However, final conclusions cannot yet be drawn, because of the small sample.

The reaction of bovine erythrocyte acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) with a set of structurally related phosphorothiolates was studied in order to investigate the properties of the phosphorylated enzymes and to identify the leaving group. OOS- and OOS-trimethyl phosphorothiolates and their triethyl analogues inhibit acetylcholinesterase reversibly and by progressive inhibition, and the phosphorylated enzymes undergo both spontaneous reactivation and aging. For each compound the enzyme-inhibitor dissociation constant, and the rate constants for inhibition (ka), reactivation and aging have been derived. The OOS-compounds are more potent inhibitors than the OOS-compounds, and the derived inhibited enzymes reactivate and age faster. By comparing reactivation and aging rate constants with those obtained from phosphorylated enzymes of known structure it was concluded that the leaving group of during phosphorylation is the S-alkyl. SSS-trimethyl and -triethyl phosphorothiolates also form reversible complexes and inhibit the enzyme progressively. With these inhibitors the phosphorylated enzymes did not reactivate either spontaneously or in response to oximes under conditions successful for the other inhibitors. The ka values (37 degrees C, pH 7.4) range from 30 M-1 X min-1 (OOS-trimethyl phosphorothiolate) to 6.7 X 10(3) M-1 X min-1 (OOS-triethyl phosphorothiolate) as compared to 1.25 X 10(5) M-1 X min-1 determined for isomalathion (O, S-dimethyl S-(1,2-dicarbethoxyethyl)-phoshporodithioate), which was used as one of the reference compounds. If the inhibitory potency of the trialkyl phosphorothiolates is calculated from measurements made after a fixed preincubation time the results in ka values will be misleading.

A statistical method or analysing the rhythmicity of several short, non‐synchronous time series in biological systems is discussed. As a first step the single series are analysed by techniques based on linear regression and variance methods. As a second step, some test statistics are proposed for combining the results of the single curves. The statistical procedure is demonstrated by two examples: fluorescence intensity of dye‐labelled Drosophila salivary gland cells in vitro and acetylcholinesterase activity in human erythrocyte suspensions.

The fluctuation in erythrocyte cholinesterase levels and a battery of liver function tests (serum Alk. Phos., GOT, GPT, LDH, r-GTP, and Tot. Chol.) were measured over a year in farm workers using pesticide sprays . The relationships between pairs of those values observed in 18 male workers and 12 female workers were them examined and the results are presented as follows. 1) For our investigation we used the subjects who had had samples drawn during the months of May, July, October, and January of the following year, because the number of subjects who had blood samples drawn every month of the study was extremely small . Thus, we examined the blood samples of 12 study subjects who had samples drawn during each of the four seasons: Spring, Summer, Fall, and Winter, respectively. 2) The coefficients of variation for serum GOT, GPT, γ-GTP, and TG, measured during the year for the twelve subjects were high, while the coefficients of variation for Alk. Pho., LAP, and Tot. Chol., as well as erythrocyte cholinesterase were low . 3) A comparision of men and women using the coefficient of variation for each of the indices revealed a significant difference (p

Dermal and respiratory exposure, and erythrocyte and serum acetylcholinesterase activity were monitored on two groups of professional pesticide applicators spraying trees with carbaryl. The mean dermal exposure to the first group was 128 mg hr-1 of carbaryl and the mean respiratory exposure was 0.1 mg hr-1. The maximum percent (%) toxic dose received by the applicators was 0.12% hr-1. The mean exposure to the second group of applicators was 59.4 mg hr-1 dermal and 0.1 mg hr-1 respiratory, for a total of 0.02% toxic dose per hr. It was estimated that 86.9% of the dermal exposure was to the forearms and hands. The rate of exposure to pads placed under the applicators clothing was approximately 1/20 that of pads on the outside of the clothing. Of the body areas monitored, the back received the least rate of exposure. It was determined, in vitro, that 10(-3) M carbaryl would inhibit human serum (pseudocholinesterase) and erythrocyte acetylcholinesterase for at least 72 hr. There was no overall inhibition of acetylcholinesterase activity in the applicators.

We describe an automated kinetic method for erythrocyte acetylcholinesterase (EC 3.1.1.7) and plasma cholinesterase (EC 3.1.1.8) based on Ellman's colorimetric method. Quinidine sulfate is used as an inhibitor of plasma cholinesterase during the measurement of erythrocyte acetylcholinesterase activity, obviating the need for washing the erythrocytes before lysis. Results by this method are compared with those obtained by the electrometric delta pH method of Michel. To emphasize the need for measuring both erythrocyte acetylcholinesterase and plasma cholinesterase activity in workers exposed to organophosphate pesticides, we present a study of serial activities of both enzymes in a person accidentally exposed to demeton-S-methyl.

Oral administration of 0.7 mg/kg/day of quinalphos to mals buffalo calves for 28 consecutive days produced marked inhibition of erythrocyte acetylcholinesterase and elevation in serum levels of aminotransferases and phosphatases without inducing apparent toxicity. The enzymic alterations were more pronounced following 1.4 and 2.1 mg/kg/day doses of quinalphos, which were lethal within 4–17 days.

The kinetic constants, Kd, k2, and ki, were determined for the inhibition by 4-nitro-phenyl methyl(phenyl)phosphinate of three cholinesterases: butyrylcholinesterase, bovine erythrocyte acetylcholinesterase and eel acetylcholinesterase. Stopped-flow kinetic evaluations and automated data acquisition and processing were employed. A broad range in affinity for the phosphinate inhibitor was observed as reflected by the binding constants, Kd. A similar wide range in the k2 values for the unimolecular inhibition step was obtained. The net bimolecular rate constants, ki, indicate equal overall reactivity for butyrylcholinesterase and eel acetylcholinesterase with a smaller inhibition rate constant for bovine erythrocyte acetylcholinesterase.

Erythrocyte acetylcholinesterase (AchE) activity was measured in the blood of 36 alcoholic subjects and 41 healthy volunteers. The mean activity in the alcoholics was significantly lower than that in the control subjects. In vitro experiments showed that ethanol inhibited the AchE activity immediately and in proportion to the concentration of ethanol used. Incubation times up to 6 h did not increase the inhibition significantly. Incubation of normal red cells with ethanol for 15 h, followed by washing, showed also that AchE activity was inhibited by the previous exposure to ethanol and that washing did not reduce the inhibitory effect. The possibility is considered that depressed erythrocyte AchE activity may be an early indication of potential disturbances of the autonomic nervous system. The importance of reporting ethanol intake in patients with organophosphorus poisoning is stressed.

Bovine erythrocyte acetylcholinesterase inhibited by 1,2,2'-trimethylpropyl methylphosphonofluoridate (soman) is reactivated rapidly but incompletely by 1 mM of the bispyridinium mono-oximes HI-6, HS-6, HGG-12 and HGG-42 (pH 7.5, 25°). These oximes, especially HI-6 and HS-6, show a higher reactivating potency than conventional reactivators, like P2S, obidoxime or TMB4. The incomplete reactivation is studied in more detail with HI-6, which is found to be the most potent reactivator. Rapid reactivation and aging take place in the presence of the oxime (10–70 μM). The reactions are not consistent with a minimum scheme involving simultaneous aging of the inhibited enzyme and reactivation and aging of an inhibited enzyme-oxime complex. The formation of aged enzyme can be described as a first-order process. The formation of reactivated enzyme proceeds in a more complicated manner. HI-6 appears to have no effect on aging of the soman-inhibited enzyme. It is concluded that HI-6, being able to compete with the rapid aging of soman-inhibited acetylcholinesterase, has an extremely high reactivating potency, on which the therapeutic effect of the oxime is based.

The purpose of this study was to compare the effects of various regimens of pyridostigmine administration on the contractile strength of skeletal muscle. Rats were exposed to pyridostigmine according to 3 dosing schedules: 2 mg/kg ip daily, 5 mg/kg X d by sc infusion, and 25 mg/kg X d by sc infusion. After 1, 4, 10, and 20 d of exposure, measurements were made of muscle tension during tetanic stimulation, and of muscle mass, erythrocyte acetylcholinesterase activity, and body weight. Pyridostigmine produced a dose-dependent decrement in the contracture generated during tetanic stimulation. Peak effect was observed after 4 d of exposure but remained depressed after 20 d. The magnitude of the decrement correlated with the frequency of the tetanic stimulation (from 20 to 100 Hz). Muscle tension at the end of the tetanic stimulus was affected to a greater extent than the initial tension. The 25-mg/kg infusion of pyridostigmine significantly depressed erythrocyte acetylcholinesterase activity throughout the study and also decreased body weight on d 1-4. No change in muscle mass was observed in any treatment group. These results show that pyridostigmine exposure results in decrements in skeletal muscle contracture that are dose-dependent, frequency-dependent, and time-dependent. The effect is probably not the result of muscle wasting and does not correlate well with erythrocyte acetylcholinesterase inhibition. The results are consistent with effects of pyridostigmine, both presynaptically and postsynaptically, at the neuromuscular junction that affect neurotransmitter release and receptor responsiveness.