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At least 811 records · Page 45Linked to original sources
PubMed1993

Correlation between concentration of cholinesterases and the resistance of animals to organophosphorus compounds.

The molar concentrations of the catalytic sites of serum cholinesterase (ChE--EC 3.1.1.8.) and cholinesterases (ChEs-acetylcholinesterase (AChE)--EC 3.1.1.7. and ChE) from brain and perfused liver of male birds, rats, swine and sheep were determined. A positive correlation between the molar concentrations of the catalytic sites of ChEs and the resistance of the animals to some organophosphorus compounds (OPhCs) was found. In addition, the present study also showed that the difference of the molar concentrations of catalytic sites of ChEs in the brain, blood serum and liver can cause varied resistance to some OPhCs.

Acetylcholinesterase↗
PubMed2006

[Effect of huperzine A on cerebral cholinesterase and acetylcholine in elderly patients during recovery from general anesthesia].

OBJECTIVE: To observe the effect of huperzine A on cerebral cholinergic system in elderly patients during recovery from general anesthesia. METHODS: Thirty elderly patients undergoing elective surgery under general anesthesia were randomized in a double-blind manner into group I (n=15) to receive huperzine A (0.3 mg/2 ml) and group II (n=15) with normal saline (2 ml) given intravenously. Huperzine A or normal saline was administered 30 min before completion of the operation, and acetylcholine (Ach) concentration in the cerebral spinal fluid (CSF) of the patients was determined using high-performance liquid chromatography with electrochemical detector (HPLC-ECD) and the activity of cholinesterase inhibitors (ChE) evaluated with automatic biochemistry analyzer before general anesthesia induction (T1) and 5 h after operation completion (T2). RESULTS: In both the groups, Ach concentration in the CSF were lower at T2 than that at T1 (P<0.01), and at T2, CSF Ach concentration was significantly higher in group I than in group II (P<0.01); in group I, the activity of CSF ChE at T2 was lower than that at T1 (P<0.01), and also lower than at T2 in group II (P<0.01). CONCLUSION: Huperzine A can inhibit cholinesterase to increase Ach, which has a positive effect on cerebral cholinergic system in elderly patients during recovery from general anesthesia.

Acetylcholine↗
PubMedDate not supplied

[Acute poisoning by insecticides with anticholinesterase activity. Evaluation of the efficacy of a cholinesterase reactivator, pralidoxime].

Pralidoxime is the most frequently used antidote in anticholinesterase insecticide poisoning, owing to its cholinesterase reactivating action. The efficiency of Pralidoxime has been retrospectively evaluated by comparing two groups of 31 patients, the first one treated by Pralidoxime in the most commonly used doses (1200mg/24H), the second one untreated. Age, sex and nature of poison were taken in consideration to make a matched distribution in both groups. The clinical and biological initial features were nearly the same in both groups; the other therapeutic measures were the same. There was no statistical difference between the both groups for evolutive criteria such as that mortality, duration of artificial ventilation, intubation, atropine administration, decrease in plasma cholinesterase. The results pleading against the use of Pralidoxime, at least at this dose, in anticholinesterase insecticide poisoning, warrant confirmation by prospective randomized studies. The efficiency of Pralidoxime warrants confirmation firstly in the course of poisonings by some clearly identified insecticides, to which pralidoxime is supposed to be the most effective, cater used in high doses, as recommended by some authors.

Cholinesterase Inhibitors↗
PubMedDate not supplied

[Inhibition of plasma cholinesterase by pancuronium and vecuronium].

Plasma cholinesterase activity was measured in patients following administration of pancuronium and vecuronium at dosages of 0.1 mg/kg. Both agents produced significant reduction in the plasma cholinesterase activity (P less than 0.01). No statistically significant difference between the inhibitory effects of these drugs was observed.

Cholinesterase Inhibitors↗
PubMedDate not supplied

[The cholinesterase properties of Daphnia magna].

It has been demonstrated that cholinesterase of Daphnia magna is capable of the hydrolysis of propionylthiocholine iodide at the highest rate as compared to the other substrates studied, the hydrolysis being inhibited by high concentrations of the substrate. The rate of splitting of acetylthiocholine iodide is similar to that of propionylthiocholine iodide, whereas the hydrolysis of butyrylthiocholine iodide is 3 times slower. Cholinesterase from D. magna is extremely sensitive to an organophosphorus inhibitor, DDVP. The value of bimolecular constant of the inhibition rate (kappa II) is equal to (1.60 +/- 0.20).10(8)1.mol-1.min-1.

Animals↗
PubMed1988

In vitro and in vivo effects of dichlorvos on blood cholinesterase activities of cattle.

Studies were conducted to ascertain in vitro effects and effects of percutaneous application (in vivo) of dichlorvos (2,2-dichlorovinyl dimethyl phosphate; DDVP) on cholinesterase activities in bovine erythrocytes and plasma. Treatment in vitro of erythrocytes and plasma with DDVP resulted in concentration- and time-dependent inhibition of erythrocyte acetylcholinesterase (AChE) and plasma cholinesterase (ChE) activities. Mean (+/- SD) DDVP concentrations required to cause 50% enzyme inhibition were 15.7 +/- 3.3 microM and 43.1 +/- 5.7 microM for AChE and ChE, respectively; however, these values required to achieve this inhibition were markedly decreased with increasing incubation time. The inhibited AChE activity failed to be reactivated after incubation of erythrocytes with 2-pyridine aldoxime methiodide (2-PAM); however, limited reactivation of inhibited AChE and ChE activities was observed with excess concentration of 2-PAM. Percutaneous application of a DDVP-containing livestock spray on cattle also caused a marked decrease in the in vivo activities of AChE and ChE; however, the inhibited enzyme activities were reactivated rapidly after incubation with 2-PAM.

Acetylcholinesterase↗
PubMed1985

Clinical observation and comparison of the effectiveness of several oxime cholinesterase reactivators.

After passing toxicity and experimental therapeutic tests, four oxime cholinesterase reactivators [PAM (pyridine aldoxime methiodide), PAC (pralidoxime, pyridine aldoxime methylchloride), TMB4 (trimedoxime), and DMO4 (obidoxime, Toxogonin, LüH6)] were compared in clinical trials. All of them proved capable of restoring erythrocyte cholinesterase activity and relieving symptoms and signs of organophosphate insecticide poisoning. Mildly and moderately poisoned patients can be treated by several injections of any one of these drugs alone, but severe cases need the synergistic action of atropine, as well as treatments for two to three consecutive days. Although response to treatment is stronger with TMB4 and DMO4, they are not recommended for routine treatment because of their dangerous adverse side effects.

Alanine Transaminase↗
PubMed1984

A new succinylcholine-based assay of plasma cholinesterase.

We describe a new method for measuring the in vitro rate of hydrolysis of the muscle relaxant succinylcholine. This substrate is hydrolyzed by plasma cholinesterase (EC 3.1.1.8). The resulting choline is determined by measuring the hydrogen peroxide formed on its oxidation by choline oxidase (EC 1.1.3.17). This is done by use of phenol and aminoantipyrine coupled to peroxidase, and yields an intense chromophore, Amax 500 nm. The assay requires 0.1 mL of plasma, and is precise and specific. The CV was 2.7% within run, 7.3% between run. For the usual (U variant) enzyme the Km is 53 mumol/L. Enzyme activity is removed by anticholinesterase antiserum, and is inhibited by dibucaine with a Ki of 2 mumol/L. Ten samples can be assayed in duplicate in an hour. This method is suited to routine use in any laboratory that has a simple spectrophotometer. The mean activity in 11 individuals with the cholinesterase phenotype UU was 105 U/L, for seven UA heterozygotes 61 U/L, and for three AA homozygotes 4 U/L. To the extent allowed by extrapolation from in vitro to in vivo results, this method should increase diagnostic accuracy and may directly predict duration of succinylcholine-induced apnea.

Alcohol Oxidoreductases↗
PubMed1984

Activity of rat blood cholinesterases following exposure of the animals to increased environmental temperature.

The acetylcholinesterase activity of erythrocytes was investigated and compared with cholinesterase activity of the blood plasma in rats exposed to elevated temperature of the environment. The rats were kept in a thermic chamber with regulated temperature, forced air flow and controlled moisture of 55-19%. The applied temperatures were 21 degrees C (control) and 28 degrees C or 37 degrees C. The rats were exposed once for 3, 6, 12 or 24 hours and repeatedly for six successive days, for six hours each day. Experiments were also performed to find whether previous exposure of the rats to raised temperature "sensities" acetylcholinesterase to the action of typical cholinesterases inhibitor (DFP). Arrhenius plots were determined for erythrocyte acetylcholinesterase of rats subjected for 6 hours to raised temperature. It was found that the activities of both enzymes undergo only slight changes in dependence on the temperature applied and the time of exposure. More pronounced changes in this activity were observed when the rats were subjected to 37 degrees C. This may have been connected with disturbance of the lipoprotein structure and with an increase of osmotic fragility of the erythrocytes. It was also noted that earlier exposure of the animals to raised environmental temperature "sensitises" the acetylcholinesterase of the erythrocytes to the action of the organophosphorus inhibitor in vivo.

Acetylcholinesterase↗
PubMed1981

[Effect of carbodiimides on the catalytic properties of cholinesterases].

The specific modifiers of the carboxylic groups - 1.3-dicyclohexylcarbodiimide (DCC) and 1-cyclohexyl-3-(2-morpholinyl-4-ethyl)carbodiimide methyl-p-toluenesulfonate (CMC) cause irreversible inhibition of acetylcholinesterase from human erythrocytes (AChE) and butyrycholinesterase from horse blood serum (BuChE). The rate of hydrolysis of both acetylcholine and non-charged substrates - phenylacetate and indophenylacetate - is thereby decreased. At initial steps of the reaction the irreversible inhibition obeys the kinetics of the pseudo-monomolecular reactions with the following values of bimolecular constants for the rates of DCC and CMC reactions: for AChE - 2.3 +/- 0.19; 5.1 +/- 0.23 M-1 min-1, for BuChE - 1.5 +/- 0.14 and (2.2 +/- 0.21) . 10(2) M-1 min-1 (25 degree, pH 7.5). The morpholinyl carbodiimide with a quaternary nitrogen. a more specific inhibitor of cholinesterases, which is of a mixed (Ki = (3.0 +/- 0.21) . 10(-4) M for AChE) and of competitive (Ki = (3.3 +/- 0.24) . 10(-5) M for BuChE) type. Under AChE modification by CMC at concentrations causing 50 - 70% inhibition, the substrate inhibition constants and the thermal stability of the non-inhibited part of the enzyme are increased. The role of functional groups of the catalytic and regulatory centers of cholinesterases in the chemical modification by carbodiimides is discussed.

Acetylcholinesterase↗
PubMed1978

Trimethaphan camsylate (Arfonad) and human plasma cholinesterase.

These results for the first time document that the brief duration of action of the ganglionic blocker, Arfonad (trimethaphan camsylate), is not due to inactivation by plasma cholinesterase. Inhibition of the enzyme in vitro by Arfonad was not altered by prior incubation of the drug in plasma at 37 degrees C for up to 16 hours nor by treatment with NaOH at 100 degrees C for 10 minutes. Both procedures inactivated succinylcholine. These results in vitro were confirmed in vivo by finding that the toxicity of Arfonad in mice was not significantly altered by these procedures whereas they rendered succinylcholine inocuous. Arfonad is a noncompetitive whereas succinylcholine is a competitive inhibitor of plasma cholinesterase using benzoylcholine as the substrate. The camphorsulfonate moiety of Arfonad was inactive in vitro but caused mild tremors in mice at relatively high doses.

Binding, Competitive↗
PubMed1980

Effect of palmitic acid on regeneration of dichlorovos-inhibited plasma cholinesterase activity in vitro.

Free fatty acids (FFA) in plasma were observed to be significantly increased (p less than 0.001) in high fat diet (HFD) rats and albumin significantly decreased (p less than 0.001) in low protein diet (LPD) rats. Dichlorovos was more toxic to HFD and LPD rats, compared to high protein diet (HPD) and standard diet (SD) rats, but these differences were not statistically significant. The spontaneous regeneration of dichlorovos-inhibited plasma cholinesterase activity in vivo was faster in the HFD rats compared to the other three dietary groups. Adding palmitic acid (PA) in vitro to the plasma system, at PA/albumin molar ratios in the range 0.53:2.83, accelerated spontaneous regeneration of dichlorovos-inhibited plasma cholinesterase activity significantly during 2-24 h periods. PA acceleration of enzyme regeneration rate did not appear to be related to PA interactions with dichlorovos-albumin binding in plasma.

Animals↗
PubMedDate not supplied

[Aminostigmine as a cholinesterase inhibitor and as an agent for treating poisonings by cholinergic blockers].

Experiments on non-inbred albino mice have demonstrated that aminostigmine is an active reversible centrally active cholinesterase inhibitor close to the properties of physostigmine, but greatly superior to it in its action duration. Clinical examinations of healthy volunteers and patients have shown that aminostigmine-induced inhibition of cholinesterase activity persists 6 hours. The agent have been found to be more highly effective in treating cholin blocker-induced intoxications than galanthamine, which manifests itself in its greater stability of the therapeutical effect achieved and in its higher ability to prevent cardiovascular events occurring in intoxication.

Acute Disease↗
PubMed1994

Correlation of time course of blood cholinesterase activity and toxic manifestations of acute methylparathion in antidote treated rats.

Study was conducted to find out the correlation between red blood cholinesterase (RBC ChE) and plasma butyryl cholinesterase (BuChE) activities and toxic signs of oral methylparathion (MPT) and their recovery pattern with or without atropine treatment in female rats. Enzyme activity was estimated before and after an oral dose of MPT (7.5 mg/kg-1) at various time intervals upto 120 hr. Antidote groups received atropine (10 mg/kg-1, i.p.), either alone or with diazepam (2.5 mg/kg-1, i.p.), at the onset of toxic signs. Inhibition of enzyme activity served as definite index of acute toxicity of MPT. RBC ChE activity correlated with the intensity of toxic signs in no-antidote rats, while in atropine treated groups, there was no correlation. BuChE levels did not correlate with toxic signs in any of the groups except in the fatal group. The resynthesis of both the enzymes was complete in 120 hr study and did not synchronize with the recovery pattern of animals from toxic signs. Compared to BuChE, RBC ChE activity was found to be a more sensitive indicator for the diagnosis of severity of MPT toxicity.

Administration, Oral↗
PubMedDate not supplied

[The conformational aspects of the interaction of the cholinesterases of Pacific Ocean squid and vertebrates with derivatives of polymethylene bis(trimethylammonium)].

Conformational properties of a series of polymethylenebis (trimethylammonium) derivatives [formula: see text] (n = 4-10), cholinesterase reversible inhibitors, were studied by molecular mechanics method. Conformation-activity relationships between these inhibitors and human erythrocyte acetylcholinesterase, horse plasma butyrylcholinesterase, cholinesterases from the brain of the frog Rana temporaria and from visual ganglia of the squid Todarodes pacificus were investigated by correlational methods. Differences in mechanisms of antienzyme actions were determined.

Acetylcholinesterase↗
PubMed1994

The effect of hepatectomy and plasma cholinesterase inhibition on cocaine metabolism and cardiovascular responses in pigs.

To determine the effects of total hepatectomy and inhibition of plasma cholinesterase activity on cocaine metabolism, we measured plasma concentrations of cocaine and its three major metabolites, benzoylecgonine, ecgonine methyl ester, and norcocaine, by high-performance liquid chromatography in three groups of male pigs. Pigs were anesthetized with sodium thiopental and lungs were ventilated with nitrous oxide in oxygen. A right carotid arterial cannula and an internal jugular venous catheter were then inserted for the administration of cocaine and for blood sampling. A Swan-Ganz catheter was inserted through the right internal jugular vein. Group 1 pigs underwent sham operation; group 2 and 3 pigs underwent hepatectomy and portocaval shunt. In addition, group 3 pigs were treated with tetraisopropyl pyrophosphoramide, a specific plasma cholinesterase inhibitor. After this preparation, pigs were given 4 mg/kg cocaine intravenously over 2 minutes. After cocaine injection, 4 ml blood was collected into heparinized test tubes containing 2.5% sodium fluoride for determination of cocaine and its metabolites at 2, 5, 10, 15, 30, 45, 60, 90, 120, 180, 240, and 300 minutes. We also measured hemodynamic responses after cocaine administration, including heart rate and rhythm, cardiac output, and arterial blood pressure. Data were analyzed by analysis of variance. Blood levels of cocaine and its metabolites were significantly different among the three groups (p < 0.05 by analysis of variance). Our results show that total hepatectomy was associated with a marked slowing of cocaine metabolism, absence of norcocaine, and increased benzoylecgonine levels when compared with the baseline values in the control pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Effects of single and repeated exposures to abate on rat behavior and cholinesterase activity.

Rats were injected i.p. with the organophosphate insecticide ABATE and tested over the next 16 days. Animals given 1000 mg/kg showed impaired performance of a previously conditioned avoidance response 6 days after injection but not 2, 8, 10, or 16 days after injection. No behavioral changes were observed in animals given 316 or 562 mg/kg. A subsequent experiment showed that the avoidance impairment in animals given 1000 mg/kg was accompanied by significant erythrocyte, plasma, and brain cholinesterase activity inhibition and decreased spontaneous motor activity. If administration of the same ABATE dose was distributed over 6 days (167 mg/kg/day), cholinesterase and motor activity depression was still evident but conditioned avoidance performance was unimpaired. The results were interpreted as differential behavioral adaption to repeated injections of ABATE.

Animals↗