Open Meter Duo: Low-Cost Instrument for Fluorimetric Determination of Cholinesterase Activity.

Environmental screening is essential due to the increased occurrence of harmful substances in the environment. Open Meter Duo (OMD) is an open-source field photo/fluorimeter that uses an RGB diode that imitates a color according to the selected wavelength and uses a UV LED from the security kit diode as an excitation light source. The prepared PCB shield with a 3D-printed aperture was connected to Arduino UNO R4 WiFi. This system was used for the fluorescent detection of cholinesterase activity with the indoxyl acetate method. Carbofuran-a toxic pesticide-and donepezil-a drug used to treat Alzheimer's disease-were tested as model inhibitors of cholinesterase activity. The limit of detection of indoxyl acetate was 11.6 µmol/L, and the IC50 values of the inhibitors were evaluated. This system is optimized for wireless use in field analysis with added cloud support and power source. The time of analysis was 5 min for the fluorimetric assay and 20 min for the optional photometric assay. The time of field operation was approximately 4 h of continuous measurement. This system is ready to be used as a cheap and easy control platform for portable use in drug control and point-of-care testing.

Acetyl-cholinesterase-inhibitors reconsidered. A narrative review of post-marketing studies on Alzheimer's disease.

The real efficacy of Acetyl-cholinesterase-inhibitors (AChEI) has been questioned. In this narrative review we evaluated their effect on cognitive decline, measured by Mini Mental State Examination (MMSE), and on total mortality rates in patients with Alzheimer's disease (AD) recruited into post-marketing open/non-randomized/retrospective studies. In AD patients treated with AChEI, the mean MMSE loss ranged from 0.2 to 1.37 points/years, compared with 1.07-3.4 points/years in non-treated patients. Six studies also reported data about survival; a reduction in total mortality relative risk between 27% and 42% was observed, over a period of 2-8 years. The type of studies and the use of MMSE to assess cognitive decline, may have introduced several biases. However, the clinical effects of AChEI seem to be of the same order of magnitude as the drugs currently used in most common chronic disorders, as regards progression of the disease and total mortality. In the absence of long-term randomized trials on "standard" unselected AD outpatients, open/retrospective studies and health databases represent the best available evidence on the possible effect of AChEI in the real-word setting. Our data support the clinical benefit of AChEI in older patients affected by AD.

Effects of fluoride on oxidative DNA damage, nitric oxide level, lipid peroxidation and cholinesterase enzyme activity in a rotenone-induced experimental Parkinson's model.

OBJECTIVE: Environmental toxins are known to be one of the important factors in the development of Parkinson's disease (PD). This study was designed to investigate the possible contribution of fluoride (F) exposure to oxidative stress and neurodegeneration in rats with PD induced by rotenone (ROT). MATERIALS AND METHODS: A total of 72 Wistar albino male rats were used in the experiment and 9 groups were formed with 8 animals in each group. ROT (2 mg/kg) was administered subcutaneously (sc) for 28 days. Different doses of sodium fluoride (NaF) (25, 50 and 100 ug/mL) were given orally (po) for 4 weeks. Malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO), oxidative DNA damage (8-OHdG) and cholinesterase (AChE/BChE) enzyme activities were evaluated in serum and brain tissue homogenates. RESULTS: Rats treated with ROT and NaF had significant increases in serum and brain MDA, NO content, and decreases in GSH. In addition, the combination of ROT and NaF triggered oxidative DNA damage and resulted in increased AChE/BChE activity. CONCLUSIONS: Findings suggest that NaF and ROT may interact synergistically leading to oxidative damage and neuronal cell loss. As a result, we believe that exposure to pesticides in combination with NaF is one of the environmental factors that should not be ignored in the etiology of neurological diseases such as PD in populations in areas with endemic fluorosis.

Computational design of new tacrine analogs: an in silico prediction of their cholinesterase inhibitory, antioxidant, and hepatotoxic activities.

Tacrine, the first drug approved for the treatment of Alzheimer's disease (AD), is a non-competitive cholinesterase inhibitor withdrawn due to its acute hepatotoxicity. However, new non-hepatotoxic forms of tacrine have been actively researched. Moreover, several recent reports have shown that oxidative stress is the cause of damage and plays a role in the pathogenesis of several neurodegenerative diseases including AD. The aim of the present study is the design of new easily synthesized tacrine analogs with less hepatotoxicity and potent antioxidant activity. In this context, a library of 34 novel tacrine analogs bearing an antioxidant fragment was designed and evaluated for its hepatotoxicity as well as anticholinesterase and antioxidant activities using computational methods. As a result, six new tacrine analogs have been proposed as potential inhibitors of cholinesterase with antioxidant activity and low or no hepatotoxicity. Furthermore, ADME calculations suggest that these compounds are promising oral drug candidates. Communicated by Ramaswamy H. Sarma.

Jatamansinol from Nardostachys jatamansi Ameliorates Tau-Induced Neurotoxicity in Drosophila Alzheimer's Disease Model.

Nardostachys jatamansi has long been used to prepare Medhya Rasayana in traditional Indian Ayurveda medicine to treat neurological disorders and enhance memory. Jatamansinol from the N. jatamansi against Alzheimer's disease (AD) showed that it could be a multitargeted drug against AD. Drosophila is an ideal model organism for studying a progressive age-related neurodegenerative disease such as AD since its neuronal organizations and functioning are highly similar to that of humans. The current study investigates the neuroprotective properties of jatamansinol against Tau-induced neurotoxicity in the AD Drosophila model. Results indicate jatamansinol is not an antifeedant for larva and adult Drosophila. Lifespan, locomotor activity, learning and memory, Tau protein expression level, eye degeneration, oxidative stress level, and cholinesterase activities were analyzed in 10, 20, and 30-day-old control (wild type), and tauopathy flies reared on jatamansinol supplemented food or regular food without jatamansinol supplementation. Jatamansinol treatment significantly extends the lifespan, improves locomotor activity, enhances learning and memory, and reduces Tau protein levels in tauopathy flies. It boosts the antioxidant enzyme activities, prevents Tau-induced oxidative stress, ameliorates eye degeneration, and inhibits cholinesterase activities in Tau-induced AD model. This study provides the first evidence that jatamansinol protects against Tau's neurotoxic effect in the AD Drosophila model, and it can be a potential therapeutic drug candidate for AD.

Cholinesterase Inhibitory Potential of Quercetin towards Alzheimer's Disease - A Promising Natural Molecule or Fashion of the Day? - A Narrowed Review.

Natural substances are known to have strong protective effects against neurodegenerative diseases. Among them, phenolic compounds, especially flavonoids, come to the fore with their neuroprotective effects. Since quercetin, which is found in many medicinal plants and foods, is also taken through diet, its physiological effects on humans are imperative. Many studies have been published up to date on the neuroprotective properties of quercetin, a flavanol derivative. However, there is no review published so far summarizing the effect of quercetin on the cholinesterase (ChE) enzymes related to the cholinergic hypothesis, which is one of the pathological mechanisms of Alzheimer's Disease (AD). However, ChE inhibitors, regardless of natural or synthetic, play a vital role in the treatment of AD. Although the number of studies on the ChE inhibitory effect of quercetin is limited, it deserves to be discussed in a review article. With this sensitivity, the neuroprotective effect of quercetin against AD through ChE inhibition was scrutinized in the current review study. In addition, studies on the bioavailability of quercetin and its capacity to cross the blood-brain barrier and how this capacity and bioavailability can be increased were given. Generally, studies containing data published in recent years were obtained from search engines such as PubMed, Scopus, and Medline and included herein. Consequently, quercetin should not be considered as a fashionable natural compound and should be identified as a promising compound, especially with increased bioavailability, for the treatment of AD.

Dual functional cholinesterase and PDE4D inhibitors for the treatment of Alzheimer's disease: Design, synthesis and evaluation of tacrine-pyrazolo[3,4-b]pyridine hybrids.

A series of tacrine-pyrazolo[3,4-b]pyridine hybrids were synthesised and evaluated as dual cholinesterase (ChE) and phosphodiesterase 4D (PDE4D) inhibitors for the treatment of Alzheimer's disease (AD). Compound 10j, which is tacrine linked with pyrazolo[3,4-b]pyridine moiety by a six-carbon spacer, was the most potent acetylcholinesterase (AChE) with IC50 value of 0.125 µM. Moreover, compound 10j provided a desired balance of AChE and butylcholinesterase (BuChE) and PDE4D inhibition activities, with IC50 value of 0.449 and 0.271 µM, respectively. The above results indicated that this hybrid was a promising dual functional agent for the treatment of AD.

Evaluation of the cholinesterase activity of a potential therapeutic cocaine esterase for cocaine overdose.

BACKGROUND: Cocaine is a commonly abused drug and there is no approved medication specifically to treat its addiction or overdose. Bacterial cocaine esterase (CocE)-derived RBP-8000 is currently under clinical development for cocaine overdose treatment. It is proven to be effective for human use to accelerate cocaine metabolism into physiologically inactive products. Besides cocaine, RBP-8000 may hydrolyze the neurotransmitter acetylcholine (ACh), however, no study has reported its cholinesterase activity. The present study aims to examine RBP-8000's cholinesterase activity and substrate selectivity to address the potential concern that this enzyme therapy might produce cholinergic side-effects. METHODS: Both computational modeling and experimental kinetic analysis were carried out to characterize the potential cholinesterase activity of RBP-8000. Substrates interacting with RBP-8000 were modeled for their enzyme-substrate binding complexes. In vitro enzymatic kinetic parameters were measured using Ellman's colorimetric assay and analyzed by Michaelis-Menten kinetics. RESULTS: It is the first demonstration that RBP-8000 catalyzes the hydrolysis of acetylthiocholine (ATC). However, its catalytic efficiency (kcat/KM) against ATC is 1000-fold and 5000-fold lower than it against cocaine at 25 °C and 37 °C, respectively, suggesting RBP-8000 has the desired substrate selectivity for cocaine over ACh. CONCLUSION: Given the fact that clinically relevant dose of RBP-8000 displays insignificant cholinesterase activity relative to endogenous cholinesterases in human, administration of RBP-8000 is unlikely to produce any significant cholinergic side-effects. This study provides supplemental evidences in support of further development of RBP-8000 towards a clinically used pharmacotherapy for cocaine overdose.

Incidencia de parálisis neuromuscular residual post anestesia general en pacientes de la Unidad de Recuperación de Cirugías programadas del Hospital Nacional Sergio E. Bernales, Abril - Junio 2013 / Incidence of residual neuromuscular paralysis post anesthesia general in patients of Surgical Recovery Unit scheduled at the National Hospital Sergio E. Bernales, April - June 2013

Introducción: El bloqueo neuromuscular residual (BNR) es una de las principales complicaciones relacionadas con el uso de agentes bloqueantes neuromusculares despolarizantes (BNM) durante la anestesia general. El objetivo de nuestro estudio es determinar cuál es la incidencia de pacientes con relajación muscular residual en la unidad de recuperación de cirugías programadas y a que factores se encuentra asociado. Metodología: Estudio observacional, transversal. Se determinara la presencia de relajación muscular residual mediante un monitor de relajación (TOF) en la Unidad de Recuperación (URPA). El análisis de los datos será descriptivo y analítico, los datos se presentaran en tablas y gráficos de dispersión. Resultados: Fueron reclutados 62 pacientes, 22 (35.5 por ciento) presentaron BNR. Resultados con asociación significativa, Neostigmina * BNR: X2=2.93, a=0.08. Horas de exposición * TOF<90 por ciento: R2=0.15, F=3.48, a<0.05. SatO2 * BNR (llegada URPA): Z=-6.50, a<0.05. Presión arterial media * BNR (salida URPA): t=2.28, a<0.05. Ventilación Espontanea * BNR: X2=8.21, a<0.05. Signos y síntomas * BNR: Rho=0.26, a<0.05. Conclusiones: El BNR se presentó en el 35.5 por ciento de los pacientes estudiados, hay una tendencia hacia el uso de neostigmina como factor protector. Las horas de exposición al relajante muscular en pacientes con TOF <90 por ciento se asocia con menores valores de TOF. El BNR influye en la presencia de hipoxia a la llegada a URPA, y de menor presión arterial media a la salida URPA. La ventilación espontánea es de menor calidad en pacientes con BNR. La ausencia de signos y síntomas se correlaciono con pacientes sin BNR, pero los mismos se presentaron en ambos grupos.

Introduction: Residual neuromuscular blockade (BNR) is a major complication associated with the use of depolarizing neuromuscular blocking agents (NMB) during general anesthesia. The objective of this study is to determine the incidence of patients with residual muscle relaxation recovery unit as elective surgery is associated with factors. Methodology: Observational, transversal. To be determined the presence of residual muscle relaxation using a relaxation monitor (TOF) in the Recovery Unit (URPA). The data analysis will be descriptive and analytical data are presented in tables and scatter plots. Results: 62 patients were recruited, 22 (35.5 per cent) had BNR. Results with significant association, Neostigmine * BNR: X2=2.93, a=0.08. Hours of exposure * TOF<90 per cent: R2=0.15, F=3.48, a<0.05. Sat02 * BNR (URPA arrival): Z=-6.50, a<0.05. Mean arterial pressure * BNR (output URPA): t=2.28, a<0.05. Spontaneous Ventilation * BNR: X2=8.21, a<0.05. Signs and symptoms * BNR: Rho=O.26, a<0.05. Conclusions: The BNR presented in 35.5 per cent of patients studied, there is a trend towards the use of neostigmine as a protective factor. The hours of exposure in patients with muscle relaxant TOF<90 per cent were associated with lower values TOF. The BNR influence the presence of hypoxia on arrival to URPA, and lower mean arterial pressure at the exit URPA. Spontaneous ventilation is of lower quality in patients with BNR. The absence of signs and symptoms was correlated with patients without BNR, but these occurred in both groups.

Pseudocolinesterasas plasmáticas: a propósito de un caso / Plasmatic pseudocholinesterase: a case report

ntroducción: La presencia de colinesterasa plasmática inhibida, disminuida o genéticamente atípica, produce bloqueo neuromuscular prolongado con el uso de succinilcolina. Objetivos: Presentar la evolución clínica de una paciente portadora de colinesterasa plasmática, con recuperación tardía por uso de succinilcolina. Presentación del caso: Se presenta evolución clínica de paciente femenina de 24 años de edad, con antecedentes de anomalía del raquis en estudio suspendido por gestación con alteraciones sensitivas en mitosis I (MI), internada en Hospital General Provincial Docente de Morón. Por embarazo a término y desproporción céfalo pélvica para operación cesárea. Examen físico y complementarios habituales negativos. En el quirófano se le realizó inducción con kethamina: 125 mg IV; atropina 0,5 mg IV y succinilcolina: 100 mg IV. Laringoscopia gentil, intubación fácil con tubo 7. Se acopló al ventilador SERVO 900D, con fracción inspirada de oxígeno (FiO2) de 0.5. Frecuencia respiratoria (FR) 12 x min y volumen corriente (VT) de 450 ml. El mantenimiento anestésico se realizó con oxígeno, aire comprimido, midazolam 5 mg IV y fentanyl: 150 µg IV, sin necesidad de repetir dosis de relajante muscular. Transcurrida 1 hora se valoró posibilidad de estar en presencia de colinesterasa atípica. Se administró una bolsa de plasma, sin obtener respuesta. Continuó intubada y acoplada al ventilador durante 6 horas a partir de la cual se recuperó y se extubó sin dificultad. Conclusiones: Ante la administración de succinilcolina nunca se debe olvidar la posibilidad de bloqueo neuromuscular prolongado por presencia de pseudocolinesterasa, pues es una complicación a tener en consideración.

Pseudocolinesterasas plasmáticas: a propósito de un caso / Plasmatic pseudocholinesterase: a case report

ntroducción: La presencia de colinesterasa plasmática inhibida, disminuida o genéticamente atípica, produce bloqueo neuromuscular prolongado con el uso de succinilcolina. Objetivos: Presentar la evolución clínica de una paciente portadora de colinesterasa plasmática, con recuperación tardía por uso de succinilcolina. Presentación del caso: Se presenta evolución clínica de paciente femenina de 24 años de edad, con antecedentes de anomalía del raquis en estudio suspendido por gestación con alteraciones sensitivas en mitosis I (MI), internada en Hospital General Provincial Docente de Morón. Por embarazo a término y desproporción céfalo pélvica para operación cesárea. Examen físico y complementarios habituales negativos. En el quirófano se le realizó inducción con kethamina: 125 mg IV; atropina 0,5 mg IV y succinilcolina: 100 mg IV. Laringoscopia gentil, intubación fácil con tubo 7. Se acopló al ventilador SERVO 900D, con fracción inspirada de oxígeno (FiO2) de 0.5. Frecuencia respiratoria (FR) 12 x min y volumen corriente (VT) de 450 ml. El mantenimiento anestésico se realizó con oxígeno, aire comprimido, midazolam 5 mg IV y fentanyl: 150 µg IV, sin necesidad de repetir dosis de relajante muscular. Transcurrida 1 hora se valoró posibilidad de estar en presencia de colinesterasa atípica. Se administró una bolsa de plasma, sin obtener respuesta. Continuó intubada y acoplada al ventilador durante 6 horas a partir de la cual se recuperó y se extubó sin dificultad. Conclusiones: Ante la administración de succinilcolina nunca se debe olvidar la posibilidad de bloqueo neuromuscular prolongado por presencia de pseudocolinesterasa, pues es una complicación a tener en consideración (AU)

Cholinesterase research at the National Institutes of Health, USA.

Presented below is a brief description of research supported by the National Institutes of Health (NIH) on cholinesterases that was discussed at the IXth International Meeting on Cholinesterases in Suzhou, China. It is a partial description of the research conducted by researchers at academic and other institutions supported by the NIH, and by some of the researchers in NIH intramural laboratories. It does not represent a comprehensive survey of all research supported by the NIH related to cholinesterases, but rather a brief discussion of some of the studies discussed at the IXth International Meeting on Cholinesterases. The article describes exciting basic, translational and clinical research on therapies for neurological and other diseases. In addition, cholinesterases that may treat substance abuse are discussed, and pesticide and chemical warfare agents that inhibit cholinesterases are highlighted as part of the NIH portfolio. It is the intent of this article to share with the international community some of the research being supported by the NIH on cholinesterases that complements many of the studies being conducted elsewhere. The information was obtained only from published articles or from abstracts available to the public within the NIH CRISP database (http://crisp.cit.nih.gov/).

Rationale for diagnosing deficiency of ChEs and for applying exogenous HuChEs to the treatment of diseases.

Recent evidence strongly demonstrates that acetylcholine (ACh) is not only involved in the function of the central and peripheral nervous systems, including the parasympathetic and somatic systems, but also acts as a ubiquitous cell signaling molecule or cytotransmitter, and as a hormone with paracrine, juxtacrine and autocrine properties. This active molecule exerts versatile and potent functions primarily through its specific nicotinic and muscarinic receptors (nAChRs and mAChRs, respectively). These functions modulate numerous biomechanisms, including cell growth, survival, proliferation and differentiation, cell-cell contact, cell cycle, locomotion, electrical activity, immune function, apoptosis, organization of the cytoskeleton, trophic functions, secretion, adhesion, resorption, and stress-response-regulation. By nature, the precise ACh levels and responses from receptors must be controlled and regulated by its degrading enzymes, the cholinesterases (ChEs), namely, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Once ChEs become critically deficient in quality and quantity, ACh signaling will be uncontrollably aberrant and persistent. An in-depth account of the fundamental roles of ChEs, comprising their diverse soluble and membrane-bound forms, in maintaining the functional equilibrium of ACh in the macro and microenvironment has been undertaken. This work also covers ACh receptors, signaling pathways, other interdependent and interrelated substances, functional processes, role of ChEs as first-line gatekeepers and defenses for the architecture of cells, tissues and organisms, physically, chemically, and structurally. The mechanisms of many diseases ranging from the acute cholinergic crisis to the chronic degenerative and hypergenerative disorders such as Alzheimer's disease, cancers, atopic dermatitis, may involve a deficiency of ChEs or imbalance between ACh and ChEs, initially or consequentially. It is therefore essential to ascertain a ChE deficiency, or an imbalance between ACh and ChEs, in tissues and body fluids in order for conducting clinical diagnosis, prevention and treatment. An argument is put forward on the rationale of applying exogenous human ChEs to reverse enzymatic deficiency and correct the imbalance between ACh and ChEs, to repair the affected receptors and protect against their further loss in the body, and consequently to alleviate the signs and symptoms of diseases. Evidence is adduced for the safety and efficacy of ChEs treatment.

Novel pharmacological approaches for the antagonism of neuromuscular blockade.

Gamma cyclodextrin and purified plasma cholinesterase are 2 novel pharmacological agents being investigated as to their suitability for antagonism of neuromuscular blockade. Both of these agents are devoid of cholinergic stimulation and the accompanying side effects because their action is independent of acetylcholinesterase inhibition. Gamma cyclodextrin antagonizes the steroidal neuromuscular blocker rocuronium via the chemical encapsulation of the molecule forming a "host-guest" complex through van der Waals and hydrophobic interactions in the plasma. Encapsulation decreases plasma drug concentrations, shifting the neuromuscular blocking drug molecules from the neuromuscular junction back to the plasma compartment resulting in a rapid recovery of the neuromuscular function. Org 25969, a modified gamma cyclodextrin, will antagonize profound neuromuscular block induced by rocuronium in approximately 2 minutes. A commercial preparation of purified human plasma cholinesterase has been shown to be effective in reversing succinylcholine or mivacurium-induced block. Administration of exogenous plasma cholinesterase also has been shown to be effective in antagonizing mivacurium-induced neuromuscular block, cocaine toxicity, and organophosphate poisoning.

A theoretical expression for the protection associated with stoichiometric and catalytic scavengers in a single compartment model of organophosphorus poisoning.

The ability of certain organophosphorus (OP) compounds to inhibit acetylcholinesterase (AChE) has made them useful for industrial (insecticides) and military (nerve agents) purposes. We have previously published a single compartment mathematical model of the interactions between OP nerve agents and the enzymes affected by these agents. That model, which could be used to predict the LD50 of seven nerve agents in rats, has been extended to include the protective actions of stoichiometric and catalytic OP-scavenger enzymes (delivered as pretreatments) so that protective ratios attributable to the scavengers may be predicted. Prediction of expected human protection from in vitro rate constant and initial enzyme level measurements is the ultimate goal for this work. The enhanced model predicts the LD50 from rate constants of the OP agent's binding reactions with AChE, carboxylesterase (CaE) and a stoichiometric scavenger (S); a first-order OP elimination rate (including a contribution due to a catalytic scavenger); and whole body estimates of AChE, CaE and S. The ratio of the scavenger-treated LD50 estimate to the scavenger-free LD50 estimate provided a theoretical expression describing the scavenger's contributions to the protective ratio. Published in vivo protective ratios for two stoichiometric scavengers (fetal bovine serum AChE and human utyrylcholinesterase) against challenge by several OP agents in mice were compared with ratios predicted by the model. A linear regression analysis of in vivo protective ratios in mice versus the ratios predicted by the model from the in vitro measurements resulted in an R(2) value of 0.902. The catalytic scavenger portion of the theory could not be validated due to a lack of published data. We conclude that the one-compartment model can be used to make reasonable estimates of the protective ratio attributable to stoichiometric scavengers, but can make no conclusions regarding the ability of the model to predict catalytic scavenger protection ratios.

Improvements in scavenger protection against organophosphorus agents by modification of cholinesterases.

The ability of stoichiometric scavengers, such as ChEs, to protect against a variety of OP agents has been demonstrated in several in vivo models. To improve the detoxification of OP agents by ChEs, several approaches have been recently used to increase the stoichiometry, stability, and in vivo effectiveness of ChEs as OP scavengers. For example, the in vitro stoichiometric neutralization of sarin by AChE was increased from 1:1 to 3200:1 by the addition of the oxime HI-6, while the in vivo stoichiometry was increased to 57:1 in mice by HI-6. The aging rate of soman-inhibited mouse AChE was reduced 12-fold in a mutant AChE (E202Q) which resulted in a two-fold increase in oxime-assisted detoxification of soman. To improve the duration of scavenger protection provided by ChEs, the mean residence times of five tissue-derived and two recombinant ChEs injected i.v. in mice were compared with their oligosaccharide profiles. The mean residence times of these ChEs were found to increase with molecular weight and with the levels of oligosaccharide sialylation. The stability of AChE in non-physiological environments was improved by immobilizing it in a polyurethane foam matrix that allowed AChE to retain enzymatic activity at high temperature (75 degrees C) where soluble enzyme denatured. These developments in scavenger technology have improved the in vivo protection provided by OP scavengers and extended their applicability to provide external decontamination of chemical agents and pesticides.

Administration of purified human plasma cholinesterase protects against cocaine toxicity in mice.

BACKGROUND: Cocaine is metabolized in part by plasma cholinesterase to form ecgonine methyl ester. Decreased plasma cholinesterase activity is associated with enhanced cocaine toxicity in both humans and animals. This study was designed to determine whether the administration of exogenous plasma cholinesterase is protective against cocaine toxicity. METHODS: Using a blinded protocol, female Swiss albino mice were randomized to receive an intraperitoneal injection of either 13.7 mg/kg of purified human plasma cholinesterase dissolved in phosphate buffered saline, or an equal volume of phosphate buffered saline as a control. One hour later, all animals received an intraperitoneal injection of either 100 or 125 mg/kg of cocaine, and the incidence of seizures and death was recorded. In a similar fashion, another group of animals was randomized to receive a human plasma cholinesterase dose of either 13.7 or 27.4 mg/kg, followed by 150 mg/kg of cocaine. RESULTS: Administration of 13.7 mg/kg of human plasma cholinesterase increased plasma cholinesterase activity by a mean of 63 +/- 13 fold, with a Tmax of 90 minutes and a Vd of 85 +/- 13 mL/kg. Cocaine's effects on seizures and death were attenuated by human plasma cholinesterase. A cocaine dose of 150 mg/kg represents an ED100 for seizures and an LD100. At this dose, lethality was reduced to 30% (p < 0.001) and seizures were reduced to 40% (p < 0.001) by administration of 27.4 mg/kg of human plasma cholinesterase. CONCLUSIONS: Pretreatment with purified human plasma cholinesterase protects mice against the convulsive and lethal effects of cocaine.

Cholinesterases as scavengers for organophosphorus compounds: protection of primate performance against soman toxicity.

The present treatment for poisoning by organophosphates consists of multiple drugs such as carbamates, antimuscarinics, and reactivators in pre- and post-exposure modalities. Recently an anticonvulsant, diazapam, has been included as a post-exposure drug to reduce convulsions and increase survival. Most regimens are effective in preventing lethality from organophosphate exposure but do not prevent toxic effects and incapacitation observed in animals and likely to occur in humans. Use of enzymes such as cholinesterases as pretreatment drugs for sequestration of highly toxic organophosphate anticholinesterases and alleviation of side effects and performance decrements was successful in animals, including non-human primates. Pretreatment of rhesus monkeys with fetal bovine serum acetylcholinesterase protected them against lethal effects of soman (up to 5 LD50) and prevented signs of OP toxicity. Monkeys pretreated with fetal bovine serum acetylcholinesterase were devoid of behavioral incapacitation after soman exposure, as measured by serial probe recognition or primate equilibrium platform performance tasks. Use of acetylcholinesterase as a single pretreatment drug provided greater protection against both lethal and behavioral effects of potent organophosphates than current multicomponent drug treatments that prevent neither signs of toxicity nor behavioral deficits. Although use of cholinesterases as single pretreatment drugs provided complete protection, its use for humans may be limited, since large quantities will be required, due to the approximately 1:1 stoichiometry between organophosphate and enzyme. Bisquaternary oximes, particularly HI-6, have been shown to reactivate organophosphate-inhibited acetylcholinesterase at a rapid rate. We explored the possibility that enzyme could be continually reactivated in animals pretreated with fetal bovine serum acetylcholinesterase, followed by an appropriate dose of reactivator, and challenged with repeated doses of sarin. In in vitro experiments, stoichiometry greater than 1:400 for enzyme:sarin was achieved; in vivo stoichiometry in mice was 1:65. Pretreatment of mice with fetal bovine serum acetylcholinesterase and HI-6 amplified the effectiveness of exogenous enzyme as a scavenger for organophosphate.