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PubMed1981

Effects of hycanthone and praziquantel on monoamine oxidase and cholinesterases in Schistosoma mansoni.

The effects of hycanthone and praziquantel on the activities of monoamine oxidases and cholinesterases were studied in the 600-g supernatant from homogenates of Schistosoma mansoni and mouse liver or brain. Hycanthone was shown to be a very potent inhibitor of monoamine oxidases from worms and mouse liver. Hycanthone also inhibited the specific and nonspecific cholinesterases of S. mansoni, but cholinesterase from mouse brain was not affected significantly by this drug. Praziquantel showed no effect on monoamine oxidase from mouse liver or the parasite; however, it was slightly inhibitory to S. mansoni cholinesterases at very high concentrations. Mouse brain cholinesterase required an even higher concentration of praziquantel to observe inhibition. The inhibition of monoamine oxidase in S. mansoni by hycanthone adds a new mode of action to our knowledge of this compound, and suggests another possibility for the development of future anthelminthics.

Animals↗

PubMed1994

Clinical importance of plasma cholinesterase for the anaesthetist.

Plasma cholinesterase is a glycoprotein synthesized in the liver and is found in plasma, liver, intestinal mucosa and other tissues. Six percent to 7% of patients in most surgical populations have an abnormal plasma cholinesterase activity and about 65% of all cases of prolonged neuromuscular blockade following succinylcholine are due to genetic factors. This review focuses on the causes and clinical significance of plasma cholinesterase for the hydrolyses of succinylcholine. Diagnosis and treatment of prolonged response to succinylcholine in phenotypically normal patients, heterozygous abnormal patients and patients homozygous for the atypical gene is mentioned. Also presented is the relationship between plasma cholinesterase and the new relaxant mivacurium, and bambuterol, a prodrug to terbutaline. Additionally, the recent developments in the identification of the plasma cholinesterase genotypes are presented.

Anesthesiology↗

PubMedDate not supplied

[Comparative characterization of the catalytic properties of blood serum cholinesterase in pigeon and hen].

Significant difference in catalytic properties of partially purified cholinesterases from blood serum of pigeon and hen was shown by photometric method using Ellman's reagent. From eight studied thioesters, pigeon cholinesterase hydrolysed with the highest rate butyrylthiocholine but hen cholinesterase--propionylthiocholine. The enzymatic hydrolysis obeyed Michaelis-Menten equation only at low concentration of substrates up to 0.15-0.5 mM. High concentration of substrates activated hen cholinesterase, but inhibited pigeon cholinesterase.

Animals↗

PubMed1997

Variations in serum cholinesterase activity in different age and sex groups.

Measurements of serum cholinesterase activity has been used to assess liver function, predict susceptibility to prolonged apnoea after administration of the muscle relaxant succinylcholine and monitor excessive exposure to the anti-cholinesterase organophosphorus insecticides (1, 2). Serum cholinesterase activity can be affected by many physiological and pathological conditions such as age, pregnancy, puerperium, obesity, some drug therapy, and liver diseases. Additionally, congenital cholinesterase deficiency, which is due to several genetic variants of the enzyme, has also been reported (3, 4). Since the enzyme activity is altered by many factors, we aimed to show the distribution of serum cholinesterase activity levels in different age and sex groups, in order to establish the reference limits in our population.

Adolescent↗

PubMedDate not supplied

[Inhibition of cholinesterases of varying origin by ordinary and betaine vinylphosphates].

The comparative study of irreversible inhibitory action of some substituted vinyl-phosphates (in usual and betaine forms on cholinesterases from different biological sources such as the human blood erythrocytes, the horse and the hen blood serum and optic ganglia of the squid) has been carried out. It is shown that betaines obtain lesser inhibitory activity as compared with the corresponding ordinary vinylphosphates. Some of tested inhibitors display expressed selectivity of action. So, the compound GL-2 reacts with cholinesterase of optic ganglia of the squid 450 000 times faster than with cholinesterase of the hen blood serum. The application of vinylphosphates as inhibitors of cholinesterases allows displaying additional differences in properties of enzymes. It is very important for comparative enzymology. These compounds may be used for detalization of type belonging and to make the classification of cholinesterases more accurate. Moreover, the estimation of anticholinesterase activity of vinylphosphates is important because these compounds may be used both in medicine and agriculture.

Acetylcholinesterase↗

PubMed1998

[Pleural fluid to serum cholinesterase ratio to discriminate between transudates and exudates: reevaluation in 177 patients].

BACKGROUND AND OBJECTIVES: In a previous study we concluded that the pleural fluid/serum (PF/S) ratio of cholinesterase was the most useful parameter to discriminate between exudates and transudates. The objective of the present study was to confirm these findings in a prospective series of patients with pleural effusion. MATERIAL AND METHODS: A total of 177 patients, consecutively studied at two institutions, with the diagnosis of pleural effusion were included in this study. Thirty-six (20.3%) effusion were transudates and 141 (79.7%) exudates; of these, 73 and 68 were of malignant and benign origin, respectively. Both PF/S cholinesterase and Light's criteria were compared. RESULTS: The PF/S cholinesterase ratio incorrectly classified 12 pleural effusions (6.8%). These included 7 out the 36 transudates (19.4%) and 5 out of the 141 exudates (3.5%), the latter of malignant etiology. Following Light's criteria, four (2.2%) exudates were misclassified, all of them transudates. The higher accuracy of Light's criteria was statistically significant (p = 0.04). CONCLUSIONS: In this series of patients, Light's criteria were more accurate than PF/S cholinesterase ratio to discriminate between transudates and exudates. From these results, the use of the PE/S cholinesterase ratio parameters is no longer recommended.

Adult↗

PubMedDate not supplied

[Effect of nitrogen source on growth of Arthrobacter simplex and its biosynthesis of cholinesterase].

The effect of organic and inorganic forms of nitrogen on biomass accumulation and cholinesterase synthesis was studied with Arthrobacter simplex var. cholinesterasus. The culture assimilates nitrogen of ammonium compounds better than other forms of inorganic nitrogen; the best nitrogen source for biosynthesis of cholinesterase is ammonium phosphate. Nitrogen of nitrates is not assimilated. The amount of biomass is almost twice as high on the medium with peptone, casein or casein hydrolysate as on the medium with mineral nitrogen, while the activity of cholinesterase on these nitrogen sources decreases 1.5--2.0 times. Yeast extract as a nitrogen source increases biomass accumulation by a factor of 2.5 and does not supress synthesis of cholinesterase. The concentration of the enzyme synthesized per unit biomass on the medium with yeast extract is the same as on the medium containing ammonium phosphate. The effect of amino acids and amides, i.e. beta-alanine, proline, amides of aspartic and glutamic acids, and their mixtures, is similar to the action of yeast extract: they stimulate biomass accumulation and do not inhibit synthesis of the enzyme. Other amino acids supress synthesis of cholinesterase. The amount of accumulated biomass in the presence of glutamic acid is twice as high as in the case of any other amino acid, and three times as high as on the medium containing ammonium phosphate. Similar action of glutamic acid is manifested when it is used in mixtures with other amino acids. On the medium containing glutamic acid as a sole source of nitrogen, an increase in biomass production is accompanied with a decrease in biosynthesis of the enzyme by 50%. Repression of the biosynthesis is less if glutamic acid is added in mixtures with proline, beta-alanine and asparagine.

Arthrobacter↗

PubMed2001

Cholinesterase inhibition by aluminium phosphide poisoning in rats and effects of atropine and pralidoxime chloride.

AIM: To investigate the cholinesterase inhibition and effect of atropine and pralidoxime (PAM) treatment on the survival time in the rat model of aluminium phosphide (AlP) poisoning. METHODS: The rats were treated with AlP (10 mg/kg; 5.55 x LD50; ig) and the survival time was noted. The effect of atropine (1 mg/kg, ip) and PAM (5 mg/kg, ip) was noted on the above. Atropine and PAM were administered 5 min after AlP. Plasma cholinesterase levels were measured spectrophotometrically in the control and AlP treated rats 30 min after administration. RESULTS: Treatment with atropine and PAM increased the survival time by 2.5 fold (1.4 h+/-0.3 h vs 3.4 h+/-2.5 h, P < 0.01) in 9 out of 15 animals and resulted in total survival of the 6 remaining animals. Plasma cholinesterase levels were inhibited by 47 %, (438+/-74) U/L in AlP treated rats as compared to control (840+/-90) U/L (P < 0.01). CONCLUSION: This preliminary study concludes that AlP poisoning causes cholinesterase inhibition and responds to treatment with atropine and PAM.

Aluminum Compounds↗

PubMedDate not supplied

[Effect of cholinesterase inhibitors and reactivators on the blocking action of dicarboxylic acid amino esters on neuromuscular conduction].

Inhibition of active cholinesterases in cats with armine or the GT-165 compound (0,0-diethyl-S-/beta-arylmethylamino) ethyl/thiophosphate methylsulphomethylate) potentiases ten- and hundred-fold the blocking action of subecholine and its derivatives on the neuro-muscular condution. The cholinesterase reactivator dipyroxime (2-5 mg/kg) quickly lifts the conduction block, provoked by muscle relaxants of the subecholine type under the cholinesterase inhibition. The subecholine analogue with a single propyl radical at each atom of nitrogen does not display any pressor action and, upon inhibition of cholinesterases, it blocks the neuro-muscular conduction when used in a dose of 0.1-0.2 gamma/kg. The maximal potentiation of the blocking action exerted by subecholine and its analogues is achieved in inhibiting not only pseudocholinesterase but acetylcholinesterase as well.

Amino Acids, Dicarboxylic↗

PubMedDate not supplied

[Reactivation of phosphorylated cholinesterase immobilized in a gelatin membrane].

The soluble and immobilized cholinesterases (acetyl cholinesterase of human blood erythrocytes (EC 3.1.1.7) and butyryl cholinesterase of equine blood serum, (EC 3.1.1.8] were inactivated by such irreversible inhibitors as diisopropyl fluorophosphate (DFP), O,O-dimethyl-O-(2,2)-dichlorovinyl) phosphate (DDVP), paraoxone, armine. The inactivated enzymes were reactivated under the effect of TMB-4 (1,1'-trimethylene-bis)-4-formyl-pyridine bromide (dioxime). The values of the reactivation rate constants proved to be equal both for the soluble and immobilized cholinesterases inactivated by the same irreversible inhibitor. The immobilized enzyme is simpler and more correct to study the reactivating action than the soluble one.

Acetylcholinesterase↗

PubMed1997

Abnormal cholinesterase activity: understanding and interpretation.

Abnormal acetylcholinesterase and cholinesterase activity may occur due to a) various physiological and pathological conditions, b) genetic factors or c) interaction with drugs and cholinesterase inhibitors. This paper reviews and discusses such conditions in which both cholinesterases show abnormal activity focusing on better understanding and interpretation of laboratory results. In particular, the mechanism of interaction of both cholinesterases with their inhibitors such as organophosphorus and carbamate compounds is discussed. Some practical recommendations concerning sampling and preparation of samples for enzyme assay are given in order to avoid errors that may affect laboratory findings.

Acetylcholinesterase↗

PubMed1986

Separation of endocytic from exocytic coated vesicles using a novel cholinesterase mediated density shift technique.

Coated vesicles isolated from rat liver perfused with diisopropylfluorophosphate (DFP) to inactivate endogenous cholinesterase contained newly synthesized secretory cholinesterase after a 30 min recovery. The cholinesterase is found in coated vesicles of presumed endocytic origin following DFP treatment and perfusion for 3 min with galactosylated cholinesterase, a ligand for the asialoglycoprotein receptor. Highly enriched populations of endocytic and exocytic coated vesicles can be separated by use of a novel cholinesterase mediated density shift technique. The two coated vesicle classes have very similar polypeptide compositions but differ significantly in the ratio of cholesterol to phospholipid.

Acetylcholinesterase↗

PubMed2006

Serum cholinesterase activity helps to distinguish between liver disease and non-liver disease aberration in liver function tests.

The diagnostic usefulness of a single determination of serum cholinesterase activity to distinguish between overt liver disease and non-liver disease clinical problems in which a few of the traditional liver function tests are abnormal was assessed. Using three groups of subjects comprising liver disease, non-liver disease, and healthy controls, we have shown that serum cholinesterase activity helped to distinguish between liver disease and non-liver disease in subjects who had abnormality of a few liver function tests. Serum cholinesterase activity helped also to distinguish between the liver disease subjects and healthy controls. There was no statistically significant difference between the mean serum cholinesterase activities of non-liver disease subjects and healthy controls. We suggest that determination of serum cholinesterase activity is a cost-effective diagnostic means of differentiating between overt liver disease and non-liver diseases where there may be aberration of some liver function tests.

Journal Article↗

PubMed1992

Plasma esterase-1 (ES-1) activity in rats is influenced by the amount and type of dietary fat, and butyryl cholinesterase activity by the type of dietary fat.

In previous work, we studied, under conditions of ad libitum food consumption, the effect of amount and type of dietary fat on plasma esterase-1 (ES-1) and butyryl cholinesterase activity in rats. This was done by the isoenergetic replacement of dietary fat by carbohydrates or by another fat source. The observed change in enzyme activity could theoretically be determined by either the dietary omission or the addition or by the combination. In the present work, we studied under restricted feeding conditions the effect of supplemental energy in various forms to determine the effect of the supplement alone. Supplemental coconut fat, but not isoenergetic amounts of either glucose or casein, raised plasma ES-1 activity. None of these supplements influenced butyryl cholinesterase activity. In a second experiment, we demonstrated that the ES-1 enhancing effect of supplemental coconut fat also occurred with fish oil, whereas the stimulatory effects of olive oil and corn oil were less pronounced. Supplemental fish oil, but not the three other fats, significantly reduced the depression in butyryl cholinesterase activity. Plasma cholesterol concentration was negatively associated with butyryl cholinesterase activity, but was not related to ES-1 activity. The two esterases were not correlated with plasma triglyceride concentration. We conclude that both the amount and type of fat in the diet of rats have specific influences on plasma ES-1 activity and that butyryl cholinesterase activity is affected by the type of fat.

Animal Feed↗

PubMedDate not supplied

Weak inhibitors protect cholinesterases from strong inhibitors (paraoxon): in vitro effect of ranitidine.

Metoclopramide (MCP) is a dopamine receptor antagonist and serotonin receptor agonist widely used as an antiemetic and gastric prokinetic drug. In addition MCP is a weak and reversible inhibitor of cholinesterases. We have shown that MCP has a cholinesterase protective effect against inhibition by organophosphates. The putative mode of protective action of MCP is competition for the active site of the enzyme with the more potent organophosphate. In the present paper we present our results using another weak inhibitor of cholinesterases: ranitidine (RAN). The purpose of the study was to quantify in vitro the extent of RAN-conferred protection, using paraoxon (POX) as an inhibitor. Paraoxon is a non-neuropathic organophosphate responsible for a large number of accidental or suicidal exposures. Red blood cell (RBC) acetylcholinesterase (AChE) activities in whole blood and butyrylcholinesterase (BChE) activities in human plasma were measured photometrically in the presence of different POX and RAN concentrations and the IC50 was calculated. Determinations were repeated in the presence of increasing RAN concentrations. The IC50 shift induced by the presence of RAN increases with the RAN concentration in a linear manner. The shift was more pronounced with RBC-AChE. The protective effect of RAN on cholinesterase could be of practical relevance in the treatment of POX poisoning. We conclude that in vivo testing of RAN as an organophosphate protective agent is warranted.

Acetylcholinesterase↗

PubMed2000

Stress does not enable pyridostigmine to inhibit brain cholinesterase after parenteral administration.

The peripherally acting cholinesterase inhibitor pyridostigmine was widely used during the Gulf War as a pretreatment against possible chemical warfare attack. Following consistent reports on long-term illness among Gulf War veterans, pyridostigmine was examined for its possible long-term effects. These effects were suggested to be induced by the combination of pyridostigmine administration and stress exposure that allowed this quaternary compound to enter the brain through stress induced changes in blood-brain barrier (BBB) permeability. Recently, pyridostigmine administration was demonstrated to inhibit brain cholinesterase following acute stress in mice. However, the effect was not replicated under similar conditions in guinea pigs. Because of the significant implication of these findings, we tested brain cholinesterase (ChE) inhibition following the administration of pyridostigmine, or the tertiary carbamate physostigmine, with or without stress in mice. Different experiments were performed to examine the contribution of gender, age (young and adults), stress (type and intensity), or strain (CD-1 and FVB/n) parameters. No inhibition of brain ChE was detected in any of these experiments. At the same time, physostigmine induced the expected decrease in brain ChE in all the experiments. Thus, we could not replicate the findings that suggest pyridostigmine can affect brain cholinesterase following stress.

Animals↗

PubMed1984

Characterization of activities and forms of cholinesterases in human primary brain tumors.

The activities and molecular forms of cholinesterases were studied in a collection of primary brain tumors consisting of primarily gliomas and meningiomas, together with samples of forebrain taken postmortem from patients suffering from diseases unrelated to the nervous system. Both types of tumors, as well as normal forebrain, contained substantial amounts of cholinesterase activity and some gliomas contained exceptionally high levels. In both normal forebrain and meningiomas, acetylcholinesterase (acetylcholine hydrolase; EC 3.1.1.7) accounted for almost all the cholinesterase activity, but in almost all gliomas elevated pseudocholinesterase (acylcholine acylhydrolase; EC 3.1.1.8) could be detected. The cholinesterase activity of both normal forebrain and gliomas migrated on sucrose gradients as a major component of 10-11 S together with a minor component of 4-5 S. In meningiomas a light (4.5 S) form was the principal component.

Acetylcholinesterase↗

PubMed1986

The inhibition of rat and guinea pig cholinesterases by anionic hydrolysis products of methylphosphonic difluoride (difluoro).

Methylphosphonic difluoride (difluoro) and its hydrolysis products, methylphosphonofluoridate (MF) and fluoride, were examined for cholinesterase-inhibiting ability in rats and guinea pigs by both inhalation and intraperitoneal exposure routes. In vivo inhibition was compared to in vitro inhibition. In the whole animal, MF was the active chemical, but in vitro under special conditions, difluoro was more potent than MF and fluoride. Rat and guinea pig blood cholinesterase were equally sensitive to inhibition by MF, but only the guinea pig displayed cholinergic signs leading to death from MF toxicity. Data imply that MF is responsible for the cholinesterase inhibition resulting from exposure to DF vapor. MF may be the first example of a moderately strong acid shown to inhibit cholinesterase and cause death from cholinergic effects.

Animals↗