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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

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.

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.

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.

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.

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.

© 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

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

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 activities of serum pseudocholinesterase and erythrocyte acetylcholinesterase in rabbits were investigated after the induction of hyperlipemia by cobalt chloride treatment.Two types of activity were found for serum pseudocholinesterase when butyrylthiocholine was used as a substrate. Both types decreased markedly under cobalt treatment associated with a marked increase in the levels of plasma triglyceride and cholesterol.Cobalt chloride failed to alter the activity of acetylcholinesterase in erythrocytes, despite higher levels of lipid peroxides which were found in erythrocyte.

Human erythrocyte acetylcholinesterase preparations which vary in lipid content, from lipid-rich to lipid-poor, have been successfully prepared using deoxycholate. It was found that the lipid content of the enzyme decreased gradually as the deoxycholate concentration used in its preparation was increased. The binding of lipid to lipid-poor preparations of the enzyme has been investigated. It was found that the activity of such preparations was highly dependent on their phospholipid contents. Maximum specific activity was associated with a fixed phospholipid content. The lipid-poor enzyme was highly activated by addition of either endogenous(membrane) or exogenous lipid. Based on the data presented, it was concluded that acetylcholinesterase is a phospholipoprotein, and its activity is highly dependent on its phospholipid component.

Four blue fox bitches were used in the experiments. Two foxes were given fenchlorphos in the feed, one 100 mg/kg body weight and the other 200 mg/kg daily for 30 days. The maximum inhibition of plasma Cholinesterase was 65 and 69 %, respectively. The corresponding values of the erythrocyte acetylcholinesterase were 43 and 63 %. For the third bitch given 0.4 mg/kg as a single dose i.v. the effect was only measurable as a small transient decrease of the plasma Cholinesterase level. Eighty % of the plasma Cholinesterase of the fourth fox, given 500 mg/kg as a single oral dose, was inhibited on the third day. The erythrocyte acetylcholinesterase activity level only showed a slight decline. This fox vomited during feeding the day after administration. Symptoms as salivation, tremors, diarrhea, pinpoint pupils and respiratory distress were never seen in any of the foxes. It was concluded that fenchlorphos administration in the feed in doses recommended to dogs is well tolerated by healthy foxes as far as Cholinesterase inhibition is concerned.

Inhibition of serum cholinesterase (ChE) and erythrocyte acetylcholinesterase by diisopropylphosphorofluoridate and amiton did not follow first order kinetics. Curving of the rate plots was concave upward and varied greatly. An equation was derived on the assumption that curving reflected inhibition of a multiple enzyme system. The curves obtained with partially purified horse ChE were then resolved into four linear components at 5° and into three linear components with an indication of a fourth at 25°. Similar results were obtained with human IV-6-3 ChE and bovine erythrocyte acetylcholinesterase. Each resolved component represented the first order rate plot for the inhibition of one form of ChE, indicating that four forms were present in each preparation. The phosphorylation (k2) and binding constants (Ka) of the various forms of horse and human ChE inhibited by amiton at 5° and of horse ChE inhibited by diisopropylphosphorofluoridate at 25° were obtained and were found to vary significantly. For example, the k2 values of horse ChE inhibited by amiton at 5° varied from 48.8 ± 2.2 min-1 to 0.0028 ± 0.0003 min-1 while Ka varied from 7.6 ± 1.2 x 10-6 m to 3.2 ± 1.5 x 10-7 m. Binding increased as k2 decreased with one exception. Since cholinesterases are probably agglomerates of subunits, this indicated that the kinetic properties of the various forms may differ profoundly with the state of agglomeration. However, additional results also indicated that not every inhibitor nor inhibition at every concentration is capable of bringing out these differences. The intercepts at t = 0 of the linear first order plots were independent of the inhibitor used and of its concentration and provided a criterion by which shifts in the relative concentrations of the various forms could be followed. Changes in either temperature or the ChE concentration changed the relative concentrations of the multiple forms, suggesting that they were interconvertible. With the horse ChE preparations the rates of reversibility increased by about 60-fold when the temperature was raised from 5° to 25°.

Anti-acetylcholinesterase activities of physostigmine, physovenine, Na-norphysostigmine, geneserine and eseramine have been investigated in vitro using erythrocyte acetylcholinesterase. The former three bases show comparable activities whereas geneserine and eseramine are inactive under the same experimental conditions. The biologically active form of these bases is discussed in light of these enzyme inhibitory studies.

(+)-Physostigmine and (+)-physovenine have been synthesized. The anti-acetylcholinesterase activities of these two bases, which have been investigated in vitro using erythrocyte acetylcholinesterase, have been found to be much lower than the corresponding activities of the alkaloids (-)-physostigmine and (-)-physovenine. Possible reasons for these activity differences are discussed.

In recent years the erythrocyte membrane has received considerable attention by many investigators. Numerous reviews on the composition [21, 111], immunologic [85, 116] and rheologic [65] properties, permeability [73], active transport [99], and molecular organization [109, 113, 117], attest to this interest. Although many studies relating to membrane enzymes have appeared, systematic reviews of this area are limited. More than a dozen enzymes have been recognized in the membrane of the human erythrocyte, although changes in activity associated with pathologic conditions are found regularly only with acetylcholinesterase (EC. 3.1.1.7). Although the physiologic functions of erythrocyte acetylcholinesterase remain obscure, the location of this enzyme at or near the cell surface gives it special significance in studies of cellular membranes and the activity alterations seen in several hemolytic disorders may be of importance in understanding certain basic disease processes. Present knowledge concerning erythrocyte acetylcholinesterase as related to health and disease, age of the individual, and erythrocyte aging is so diffuse that a review of this subject seems to be warranted.

This paper describes the synthesis of 1, a spin-labeled analog of N,N-dimethyl-2-phenyl-aziridinium chloride 2. The compound is formed in situ from 3b and acts as a poor competitive inhibitor of bovine erythrocyte acetylcholinesterase with a Ki value of M.

ABO hemolytic disease of the the newborn without hyperbilirubinemia is described in 17 full-term infants. The erythrocyte characteristics, such as reticulocytosis, microspherocytosis, and positive indirect antiglobulin (Coombs') test, resembled those in ABO disease with hyperbilirubinemia. Erythrocyte acetylcholinesterase activity was reduced in this group to the same degree as in the more severely affected infants. Negro infants predominated over white, in a 2.5:1 ratio in this mild ABO group.

Plasma cholinesterase (pChE) levels and erythrocyte acetylcholinesterase (eAChE) levels were studied in 6 cows before, during and after parturition (Group I), their calves (Group II), 38 cows suffering from parturient paresis (Group III) and 14 newly delivered non-paretic cows (Group IV). The mean of the pChE level in Group I was 1.5 μkat/1 ± 0.20 before parturition and decreased significantly (P ≦ 0.05) to 1.2 ukat/1 ± 0.16 after parturition. The eAChE level was before parturition ≅ 140 ukat/1 and decreased to ≅ 130 μkat/1 4–5 weeks after parturition. At birth the pChE level was 12.8 ukat/1 ± 5.9 in Group II. After 4 weeks the level had decreased to 2.3 ukat/1 ±0.3. In the bull calves the pChE level started to increase when they were 6 weeks old and reached a level of 5.7 μkat/1 ± 0.6 before slaughter at 6 months of age. The heifers did not show this increase. They had a level of around 2 μkat/1 throughout the investigation. The eAChE level at birth was 119 μkat/1 and increased slowly to a level of 145 μkat/1 at 6 months. No differences between the sexes were found. The cows suffering from parturient paresis had a pChE level of 1.80 μkat/1 ± 0.30 before treatment with calcium (Ca). The level decreased significantly (P ≦ 0.001) after Ca-infusion to a level of 1.67 ukat/1 ±0.29. Group IV had a pChE level of 1.65 μkat/1 ± 0.42 at parturition. Two to 4 months later the cows that had recovered from milk fever had a level of 1.61 μkat/1 ± 0.31 and the control cows 1.66 ukat/1 ± 0.48. No differences between the groups were found for the eAChE level. The findings show that parturition influences the pChE level in cows and that sex influences the pChE level in calves between 6 weeks to at least 6 months of age. Furthermore the elevated pChE level found in the cows suffering from parturient paresis before Ca infusion may be a further sign of a disturbance in the cholinergic system with a special preference to the neuromuscular junctions.

1. A procedure is described for determining the affinity constant K(a) and the phosphorylation constant k(p) for the inhibition by di-isopropyl phosphorofluoridate of erythrocyte acetylcholinesterase and serum cholinesterase. The procedure depends on the use of a specially designed reaction vessel with which incubation times as short as 1.2sec. could be obtained at any convenient temperature. 2. The K(a) of acetylcholinesterase decreased from 1.58 (+/-0.22)x10(-3)m at 5 degrees to 1.17 (+/-0.10)x10(-3)m at 25 degrees and the associated change in enthalpy was 2980 cal. 3. The k(p) of acetylcholinesterase increased from 11.9 (+/-0.7)min.(-1) at 5 degrees to 40.7 (+/-1.4)min.(-1) at 25 degrees , indicating an activational energy of 9600 cal. The change in entropy associated with K(a) was 23.5 cal. degree(-1) at 25 degrees . 4. At 5 degrees , the K(a) and k(p) of serum cholinesterase were 9.95 (+/-1.10)x10(-6)m and 11.2 (+/-0.63)min.(-1) respectively. 5. The 150-fold difference in the inhibitory power of di-isopropyl phosphorofluoridate for the two cholinesterases was attributed entirely to differences in affinity.

ACETYLCHOLINESTERASE (ACHE) activity appears to be located at the outer surface of the human erythrocyte1. We have previously shown that ACHE activity is reduced in newborn children affected with ABO haemolytic disease2. A similar defect has been detected in erythrocytes of patients with paroxysmal nocturnal haemoglobinuria (PNH)3. Watson4 has reported that in contrast to normal erythrocytes, those from patients with PNH do not bind penicillin G. In an attempt to establish further similarities between the erythrocytes of infants with ABO disease and the cells of patients with PNH we tested penicillin-binding capacity. Using the technique described by Watson et al.5 with a highly sensitive strain of β-haemolytic streptococci as indicator, we could confirm the inability of PNH erythrocytes to bind penicillin but could not detect decreased binding by red cells from infants with ABO haemolytic anaemia compared with normal adult erythrocytes. Unexpectedly, when membranes from penicillin-treated red cells were tested for ACHE activity, significant inactivation was noted. This observation prompted an investigation of the effects of this antibiotic on erythrocyte ACHE activity. Additional indications for conducting these studies were the recent demonstrations of antipenicillin antibodies6,7 and of in vivo coating of erythrocytes by penicillin8 in cases of haemolytic anaemia caused by administration of penicillin.

Background: As pesticide use is increasing and proper handling training is lacking, exposure to pesticides and intoxications are an important public health problems among farmers in developing countries. This study describes pesticide use among farmers and compares symptoms of possible acute intoxication and Erythrocyte Acetylcholinesterase(AChE) levels among vegetable farmers with a control group of blood donors in Nepal. Methods: A cross-sectional study was carried out among 90 pesticide-exposed farmers and a control group of 90 blood donors. Participants were randomly selected and data were gathered through questionnaires, observation and blood test. Chi-square test, logistic regression and Student's t-test were used for data analysis to describe pesticide use and compare symptoms and AChE levels between the two groups. This study was approved by Nepal Health Research Council. Results: The majority of pesticides used were WHO class II, classified as moderately hazardous. The mean numbers of personal protective equipment used by farmers were 2.22 (95% CI: 1.89; 2.54). Out of five hygienic practices asked, farmers followed 3.63 (95% CI: 3.40; 3.86) hygienic practices on the average. Farmers reported more symptoms of possible pesticide intoxication in the past month than did controls, mean 5.47 (95% CI: 4.70; 6.25) versus 2.02 (95% CI: 1.63; 2.40) (p Background: As pesticide use is increasing and proper handling training is lacking, exposure to pesticides an intoxications are an important public health problems among farmers in developing countries. This study describe pesticide use among farmers and compares symptoms of possible acute intoxication and Erythrocyt Acetylcholinesterase(AChE) levels among vegetable farmers with a control group of blood donors in Nepal Methods: A cross-sectional study was carried out among 90 pesticide-exposed farmers and a control group of 9 blood donors. Participants were randomly selected and data were gathered through questionnaires, observatio and blood test. Chi-square test, logistic regression and Student's t-Test were used for data analysis to describ pesticide use and compare symptoms and AChE levels between the two groups. This study was approved by Nepa Health Research Council Results: The majority of pesticides used were WHO class II, classified as moderately hazardous. The mean number of personal protective equipment used by farmers were 2.22 (95% CI: 1.89; 2.54). Out of five hygienic practice asked, farmers followed 3.63 (95% CI: 3.40; 3.86) hygienic practices on the average. Farmers reported mor symptoms of possible pesticide intoxication in the past month than did controls, mean 5.47 (95% CI: 4.70; 6.25 versus 2.02 (95% CI: 1.63; 2.40) (p < 0.05). The mean haemoglobin-Adjusted AChE(Q) was significantly lower amon farmers compared to controls, 28.92 (95% CI: 28.28; 29.56) U/g versus 30.05 (95% CI: 29.51; 30.60) U/g, (p = 0.01). Th risk of a farmer having lower Q level was about 3 times (OR = 2.95; 95% CI: 1.16; 7.51) greater than controls Conclusion: Nepalese farmers exposed to pesticides have significantly more symptoms of possible pesticid intoxication than a control group of healthy individuals. A lower mean haemoglobin-adjusted AChE level was see among farmers compared to the controls. The use of highly toxic pesticides, inadequate use of personal protectiv equipment and poor hygienic practices might explain the reason for symptoms of pesticide intoxication and a lowe AChE level among farmers. Education and information of farmers should be undertaken to remediate these problems.

NITROGEN mustard (HN2) is known to inactivate certain enzymes, particularly hexokinases and phosphatases1, in addition to the better-known effects on nucleic acids common to all alkylating agents1–5. In the course of examining the effects of nitrogen mustard on circulating erythrocytes, it became important to assay its effect, if any, on erythrocyte acetylcholinesterase. This enzyme is located on the red cell surface, accessible to trypsin inactivation6.

ERYTHROCYTE acetylcholinesterase (AChE) is strongly bound to the cell membrane1. To isolate and purify this enzyme, it must be removed from the membrane and brought into solution. Methods used for this purpose have included treatment with butanol2, digestion with pancreatin3, or addition of a surface-active material4,5. More recently, we have succeeded in solubilizing the enzyme from bovine erythrocytes by disintegrating the lysed cells by ultrasonic vibration.