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PubMed1992

Pesticide exposure and cholinesterase levels among farm workers in the Republic of South Africa.

A preliminary survey was undertaken to establish the extent of pesticide exposure in a farming community. The area under investigation included a coffee plantation in the northern region of South Africa. Cholinesterase levels in red blood cells and plasma were used as markers to monitor the extent of organophosphate and carbamate exposure. Sixty-nine farm workers with specific pesticide exposure were selected for the study, and the frequency of the different symptoms which may be related to pesticide exposure was determined by interview and questionnaire. Of the workers, 77% had their red blood cell cholinesterase levels below the normal reference range, while 27% of the workers had depressed plasma cholinesterase levels.

Agriculture↗
PubMed1987

A trans Golgi-derived exocytic coated vesicle can contain both newly synthesized cholinesterase and internalized transferrin.

We used a cholinesterase-mediated density shift protocol to investigate the movement of internalized transferrin (Tf) through endo- and exocytic coated vesicles (CVs) in the perfused rat liver. Upon internalization, exogenous 125I-Tf was found in endocytic CVs but not in cholinesterase-containing (i.e., exocytic) CVs (0-40 min). Between 1 and 2 hr, 125I-Tf began to appear in exocytic CVs. The origin of the exocytic CV was further investigated. After perfusion of the liver with asialotransferrin, the exocytic CVs were shown to contain resialylated Tf, indicating that the trans Golgi was the origin of this class of CVs. The resialylated Tf accumulated in the extracellular medium with kinetics very similar to the time course for appearance of Tf in cholinesterase-containing, exocytic CVs, suggesting that these CVs are directly involved in the transfer of material from the trans Golgi to the cell surface.

Animals↗
PubMed1992

In vivo gene amplification in non-cancerous cells: cholinesterase genes and oncogenes amplify in thrombocytopenia associated with lupus erythematosus.

The ACHE and BCHE genes, encoding the acetylcholine hydrolysing enzymes acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE), co-amplify with several oncogenes in leukemic patients with platelet deficiency (thrombocytopenia). This and other experiments implicated ACHE and BCHE in the development of bone marrow megakaryocytes, the progenitors of platelets. Therefore, we wished to find out whether cholinesterase gene amplification would also occur in non-cancerous platelet disorders and, if so, whether oncogenes would amplify in such cases as well. The autoimmune disease systemic lupus erythematosus (SLE) presents an appropriate model system for this issue, since patients with SLE may suffer from thrombocytopenia resistant to most treatment modalities. Here, we report a 40-80-fold amplification of genomic sequences from the ACHE and BCHE genes as well as the C-raf, V-sis and C-fes/fps oncogenes in peripheral blood cells from an SLE patient with severe thrombocytopenia. PvuII restriction analysis and DNA blot hybridization of the amplified ACHE and BCHE sequences demonstrated apparent aberrations in both genes, suggesting that malfunctioning of modified, partially amplified cholinesterase genes may be involved in the etiology of thrombocytopenia associated with SLE. These observations imply that cholinergic mechanisms regulate megakaryocytopoiesis, shed new light on the diverse hematologic findings characteristic of SLE, and may become valuable as diagnostic, treatment and prognostic tools in the follow-up of patients suffering from thrombocytopenia associated with SLE. Furthermore, these findings reinforce the notion that cholinesterase gene amplifications are causally related with platelet abnormalities in multiple hemopoietic disorders.

Acetylcholinesterase↗
PubMed1989

A naturally occurring molecular form of human plasma cholinesterase is an albumin conjugate.

Human plasma cholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) consists of four main molecular forms designated as C1, C2, C3 and C4 according to their electrophoretic mobility on gels. The major component, C4, is the tetrameric form; C1 and C3 are the monomeric and dimeric forms, respectively. The C2 form, which has an apparent free electrophoretic mobility higher than that of the three size isomers, and, moreover, a higher isoelectric point, was found to be a covalent conjugate between the cholinesterase monomer and serum albumin. This result is supported by the following arguments: the non-catalytic subunit of C2 was found to be a carbohydrate-free protein of apparent molecular mass 65 kDa that could not be labelled by diisopropylfluorophosphonate in the labelling conditions of esterases. It possesses a high affinity for a long-chain aliphatic ligand (a substituted octadecylamine) and for Cibacron blue F3 GA, and could be adsorbed on an immunoadsorbent for albumin. The two subunits of C2 are disulfide bridge linked; the active center of the cholinesterase subunit is partly masked by the albumin molecule. The conjugation reaction very likely occurs in the hepatic cell and not in plasma.

Butyrylcholinesterase↗
PubMed1975

The use of cholinesterase in severe head injury.

White rats were subjected experimentally to head injury, and also observations were made on them and on 12 patients with head injuries. It was found that injection of cholinesterase brought back to normal function the endogenous cholinesterase system, the adrenal cortex and the properdine--albumin complex system. Stabilization of these indices of homeostatic activity improved the chances of survival of the animals and patients. It was concluded that it would be desirable to administer cholinesterase more frequently in the treatment of head injury.

17-Hydroxycorticosteroids↗
PubMed1992

Effect of hypolipidemic drugs on cholinesterase activity in the rat.

1. The effect of four hypolipidemic agents with different mechanisms of action (fenofibrate, probucol, colestipol and nicotinic acid) on plasma and liver cholinesterase has been studied. 2. Liver weight and liver weight/body weight ratio increased only after treatment with fenofibrate. 3. Plasma and liver cholinesterase activity increased markedly after fenofibrate, a strong peroxisome proliferator, and slightly after nicotinic acid, a weak peroxisome proliferator. 4. The data obtained suggest that increased cholinesterase activity is due to increased rate of fatty acid oxidation caused by peroxisome proliferators.

Animals↗
PubMed1984

Factors influencing the cholinesterases of cerebrospinal fluid in the anaesthetized cat.

Both acetylcholinesterase and non-specific cholinesterase are found in cerebrospinal fluid and blood plasma of the cat; the ratio of activities acetylcholinesterase/non-specific cholinesterase is about 1.5 in cerebrospinal fluid and 0.15 in plasma. A search was made for factors capable of influencing the concentration of the two cholinesterases in cerebrospinal fluid. Either the ventricular system was perfused with artificial cerebrospinal fluid from a lateral ventricle to the aqueduct, or the atlanto-occipital membrane was punctured and cerebrospinal fluid was collected continuously from the cisterna magna. Factors studied included: (a) procedures affecting the composition or formation of cerebrospinal fluid, such as changes in the ionic constituents of the perfusate, the inhibition of cerebrospinal fluid formation by acetazolamide or ouabain, or the rapid intra-carotid infusion of hypertonic urea; (b) arousal (noise or stimulation of the central ends of the sciatic nerves), or deepening of anaesthesia; (c) changes in blood pressure; (d) central stimulants and depressants, pyrogens, prostaglandins, antagonists of acetylcholine. Whereas most procedures or drugs tested increased the concentration of acetylcholinesterase, some central depressants (e.g. chlorpromazine) reduced, while another (ether) increased the appearance of acetylcholinesterase in the cerebrospinal fluid. The effect of ether was, in all probability, due to damage to the blood-brain barrier. A rise in acetylcholinesterase concentration was obtained upon stimulation of the central ends of the sciatic nerves; this was inhibited by atropine but not by N-methylatropine, indicating that the rise was due to increased nervous activity and not to the circulatory effects of the stimulation, since the changes in blood pressure caused by the stimulation remained the same after atropine administration. Amphetamine or leptazol raised the levels of acetylcholinesterase but it was not possible to determine whether this was due only to increased central nervous activity, since there was invariably leakage through the blood-brain barrier which by itself would be sufficient to produce the effect. A rise in the level of acetylcholinesterase was seen after administration of pyrogen; this was apparently not a simple effect of warming the body, but due to the action of the pyrogen on centers concerned with temperature control, since warming the animal by external heat failed to produce a similar change.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1991

Pseudomonas aeruginosa cholinesterase and phosphorylcholine phosphatase: two enzymes contributing to corneal infection.

Choline, acetylcholine and betaine used as the sole carbon, nitrogen or carbon and nitrogen source increase cholinesterase activity in addition to phosphorylcholine phosphatase and phospholipase C activities in Pseudomonas aeruginosa. The cholinesterase activity catalyses the hydrolysis of acetylthiocholine (Km approx. 0.13 mM) and propionylthiocholine (Km approx. 0.26 mM), but not butyrylthiocholine, which is a pure competitive inhibitor (Ki 0.05 mM). Increasing choline concentrations in the assay mixture decreased the affinity of cholinesterase for acetylthiocholine, but in all cases prevented inhibition raised by high substrate concentrations. Considering the properties of these enzymes, and the fact that in the corneal epithelium there exists a high acetylcholine concentration and that Pseudomonas aeruginosa produces corneal infection, it is proposed that these enzymes acting coordinately might contribute to the breakdown of the corneal epithelial membrane.

Acetylcholine↗
PubMed2004

Differential effects of lipid-lowering agents on human cholinesterases.

OBJECTIVES: Epidemiologic reports indicate that lipid-lowering agents (LLAs) protect against dementia. We hypothesized that LLAs might affect cholinergic systems. The effects of LLAs on the activity of cholinesterases were examined. DESIGN AND METHODS: Odds ratios and relative risks were calculated from clinical studies of LLAs and dementia and compared with their impacts on human cholinesterases. Representative LLAs were examined for their effects on the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) using Ellman's assay. RESULTS: Epidemiological studies, but not clinical trials, showed lower odds of dementia in patients taking "statins". Comparison of LLAs indicated that "statins" most consistently produced apparent protection. Individual "statins" showed differential cholinesterase inhibition. Lovastatin and simvastatin significantly inhibited butyrylcholinesterase, while mevastatin, pravastatin and the "non-statins" did not. None of the LLAs inhibited acetylcholinesterase. CONCLUSIONS: Some "statins" inhibit butyrylcholinesterase. This inhibition suggests a possible means whereby "statins" could protect against dementia.

Cholinesterase Inhibitors↗
PubMed2005

Analysis of mutation of the plasma cholinesterase gene in a man who had died following a traffic accident.

We analyzed mutation of the butyrylcholinesterase (BCHE) gene in a 69-year-old man on whom a forensic autopsy had been performed after he had died following a traffic accident. Extremely low plasma cholinesterase activity had been pointed out by the emergency doctor at the hospital prior to his death and based on this, organophosphorus poisoning had been suspected. However, no pesticides, which could have reduced the plasma cholinesterase activity, were detected by toxicological analysis using GC/MS. Subsequently, one base insertion was found in exon 2. The frame shift mutation had occurred because a homozygous extra T had been inserted between nucleotides 1343 and 1344, resulting in the appearance of a stop codon in codon 454 (AGA454TAA, Arg454stop). This heterozygous frame shift mutation at this point was identified in the man's son. It is likely that there may be many such latent patients with abnormal plasma cholinesterase activity, and accordingly we should always bear this fact in mind and should carry out molecular genetic testing for an accurate diagnosis of this deficiency.

Accidents, Traffic↗
PubMed2006

The use of serial measurement of plasma cholinesterase in the management of acute poisoning with organophosphates and carbamates.

OBJECTIVE: To evaluate the benefits of using serial measurements of plasma cholinesterase (butyrylcholinesterase, BuChE) activity in the management of cholinesterase inhibitor insecticidal poisoning. METHOD: After establishing and validating BuChE activity test, and making it available for clinical service in the toxicology laboratory at Jordan University Hospital. Serial measurements of BuChE were performed on samples taken from 10 symptomatic patients presented with the manifestations of poisoning due to acetylcholinesterase inhibitor insecticides during the year 2001. The number of serial repeats of BuChE activity tests ranged from 2 to 4 and from 8 to 11 for patients with carbamates and organophosphates (OPs) poisoning, respectively. The results of serial measurement of BuChE obtained from each patient's samples were used to draw a curve; three different types of curves were obtained from all patients samples. RESULT: The obtained curves were found to follow our three proposed curves, which support our point view regarding the importance of the proposed curves in the differential diagnosis and treatment of cholinesterase inhibitor pesticides poisoning. CONCLUSION: This study pointed out the importance of utilizing serial measurements of BuChE activity in the diagnosis and the management of organophosphates and carbamates poisoning. The BuChE activity results were used to support diagnostic and prognostic criteria that guided patient management and follow up. Applying those curves to large number of patients' samples will enhance its credibility. The study also demonstrated the importance of direct contract between toxicologist and physician in treatment of the pesticides poisoned patients.

Adolescent↗
PubMed2004

Cholinesterase inhibitors: new roles and therapeutic alternatives.

An important aspect of brain cholinesterase function is related to enzymatic differences. The brain of mammals contains two major forms of cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The two forms differ genetically, structurally and for their kinetics. Butyrylcholine is not a physiological substrate in mammalian brain which makes the function of BuChE of difficult interpretation. In human brain, BuChE is found in neurons and glial cells as well as in neuritic plaques and tangles in Alzheimer disease (AD) patients. While AChE activity decreases progressively in the brain of AD patients, BuChE activity shows some increase. In order to study the function of BuChE, we perfused intracortically the rat brain with a selective BuChE inhibitor and found that extracellular acetylcholine increased 15 fold from 5 to 75nM concentrations with little cholinergic side effects in the animal. Based on these data and on clinical data showing a relation between CSF BuChE inhibition and cognitive function in AD patients, we postulated that two pools of cholinesterases may be present in brain, the first mainly neuronal and AChE dependent and the second mainly glial and BuChE dependent. The two pools show different kinetic properties with regard to regulation of ACh concentration in brain and can be separated with selective inhibitors. Within particular conditions, such as in mice nullizygote for AChE or in AD patients at advanced stages of the disease, BuChE may replace AChE in hydrolyzing brain acetylcholine. Based on the changes of ChE activity in the brain of AD patients, a rational indication of selective BuChEI (or of mixed double function inhibitors) is the treatment of advanced cases. A second novel aspect of ChEI therapy is the emerging of new indications which include various forms of dementia such as dementia with Lewy Bodies, Down Syndrome, vascular dementia and Parkinson Dementia. Clinical results demonstrate examples of versatility of cholinergic enhancement.

Acetylcholinesterase↗
PubMed1997

Association of cholinesterases with amyloid in extracellular neurofibrillary tangles.

Double-labeling techniques conclusively demonstrated that extracellular neurofibrillary tangles immunoreactive for beta protein were also positive for cholinesterases. Ultrastructurally, cholinesterases decorated bundles of amyloid-like filaments, which appeared intermingled with straight filaments and cellular processes. A lighter labeling of esterases was also seen over most straight filaments. These observations extend the consistent association of cholinesterases with fibrillary beta-amyloid protein to a new location in neurofibrillary tangles.

Aged↗
PubMed2003

Stress interacts with peripheral cholinesterase inhibitors to cause central nervous system effects.

Pyridostigmine bromide (PB), a peripheral cholinesterase inhibitor, has been shown to have central cholinesterase inhibition properties under certain conditions (such as when ingested with other chemical compounds or following a high level of stress). Here we tested if stressing rats, using an intermittent 1 hr tailshock protocol, affected the degree of brain acetylcholinesterase (AChE) inhibition caused by a subsequent single injection of PB (2.0 mg/kg) or neostigmine bromide (NB, 0.32 mg/kg), another peripheral carbamate cholinesterase inhibitor. Stressed rats treated with PB had lower levels of AChE activity in the basal forebrain/striatum, but not in other brain areas. Stressed rats treated with NB did not show basal forebrain/striatum AChE activity changes but did show minor reductions of AChE activity in the cortex and cerebellum. These results confirm that prior stress can change the characteristic actions of certain peripherally acting drugs, thus possibly leading to unexpected central nervous system effects. Possible causes for these effects are discussed.

Acetylcholinesterase↗
PubMed2002

An evaluation of hemolymph cholinesterase activities in the tropical scallop, Euvola (Pecten) ziczac, for the rapid assessment of pesticide exposure.

The use of sequential measurements of hemolymph cholinesterase activities as a non-invasive biomarker of seasonal organophosphate/carbamate exposure was investigated for the tropical scallop, Euvola (Pecten) ziczac. Overall activities of both acetylcholinesterase and butyrylcholinesterase were relatively high compared to studies with bivalve tissues. Acute in vivo experiments showed inhibition of hemolymph acetylcholinesterase activity at concentrations of the organophosphate insecticide chlorpyrifos of 0.1, 1 and 10 ng l(-1). Monthly sampling of hemolymph from scallops at two sites in Bermuda over a 15 month period showed seasonal acetylcholinesterase and butyrylcholinesterase inhibition. Direct and indirect evidence suggests that this inhibition did not relate to biochemical or physiological changes associated with gonad maturation and spawning, but rather reflected diffuse contamination of the marine environment by cholinesterase inhibitors or increased bioavailability of such inhibitors at these times. Repetitive sampling of scallop hemolymph for cholinesterase activities represents a rapid, sensitive and non-invasive method for assessing seasonal, sublethal pesticide exposure in these commercially important bivalves and suggests a wider use in marine pollution monitoring.

Animals↗
PubMed1989

Fine structural localization of non-specific cholinesterase activity in rat tendon organs.

Electron microscopical localization of non-specific cholinesterase (nChE) activity was studied in tendon organs of the rat hindlimb muscles. The comparison between neurotendinous part (with high nChE activity) and purely collagenous compartment(s) (with very low nChE activity) demonstrated that Schwann cells are the fundamental source of this enzyme in rat tendon organs. Although particles of the nChE reaction product were also found in and around fibroblasts in both neurotendinous and purely collagenous compartments, their contribution to the overall nChE was not significant. nChE activity in rat tendon organs displayed heterogeneity along the Ib sensory axon; the highest activity was related to the Schwann cell investment of the unmyelinated part of Ib axon, lower activity to sensory terminals covered only by basement membrane and negligible activity to the myelinated part of sensory axons. Particles of the non-specific cholinesterase reaction product persisted in the basement membrane of Schwann cells 20 d after degeneration of Ib sensory axons and their terminals. The function of non-specific cholinesterase in sensory receptors is still not clear. It is suggested that this enzyme may be involved in the maintenance of the ionic milieu around sensory axon terminals during or after functional activity.

Animals↗
PubMed2002

Stereoselectivities of enantiomers of huperzine A in protection against beta-amyloid(25-35)-induced injury in PC12 and NG108-15 cells and cholinesterase inhibition in mice.

Recently, the potent cholinesterase inhibitor (-)-huperzine A (HupA) was demonstrated to protect neuronal and glial cells against the cytotoxicity of beta-amyloid (Abeta). Since the unnatural (+)-HupA is a much less potent inhibitor, it was of interest to examine the stereoselectivity of cellular protection by the two isomers. In the present study, effects of (+)- and (-)-HupA on Abeta(25-35)-induced injury were compared in PC12 and NG108-15 neuroblastoma cell lines. Following a 24 h exposure to 1 microM Abeta(25-35), cell survival was markedly reduced, but preincubation with (+)-HupA or (-)-HupA (0.1-10 microM) enhanced survival significantly. The potency of (-)-HupA and (+)-HupA in protecting against Abeta toxicity was similar. This result contrasted with the stereoselectivity of cholinesterase inhibition in vitro and in vivo, in which (-)-HupA is about 50-fold more potent than (+)-HupA. It is concluded that the neuroprotective properties of HupA enantiomers have no relation to anti-cholinesterase activity.

Acetylcholine↗
PubMed2002

Effect of long-term aluminum feeding on kinetics attributes of tissue cholinesterases.

Aluminum (Al) is considered a potential etiological factor in Alzheimer's disease (AD). Neurotoxicity from excess brain exposure to Al is documented from both clinical observations and animal experiments. A key role of the acetylcholine system in memory disturbances that characterize AD has been reported. On this basis, we studied the effect of long-term Al feeding on kinetic properties of cholinesterases employing the rat as experimental model. Animals were given prolonged treatment with soluble salts of Al (100mg AlCl(3)/kg body weight mixed with food for 100-115 days), and the kinetic properties of cholinesterases (acetylcholinesterase, AChE, and butyrylcholinesterase, BChE) were determined in different tissues. Prolonged treatment with Al had no effect on the K(m) values of the soluble and membrane-bound forms of AChE in the brain, but V(max) was instead decreased in all the components of soluble and membrane-bound forms of AChE in the brain. In addition, the Al treatment resulted in complete loss of the component II of erythrocyte membrane AChE. Surprisingly, after prolonged treatment with Al, higher V(max) was observed in all the components of soluble and membrane-bound forms of BChE in the heart and liver. Variable effects of Al exposure were observed on temperature kinetic properties of cholinesterases. Altogether these findings indicate that long-term Al feeding results in inhibition of AChE, while an opposite effect is observed on BChE. Decreased V(max) of the brain AChE could represent the mode of action through which Al may contribute to pathological processes in Al-induced neurotoxicity.

Acetylcholine↗