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At least 37 records · Page 2Linked to original sources
PubMed1992

Poisoning from oral ingestion of carbofuran (Furadan 4F), a cholinesterase-inhibiting carbamate insecticide, and its effects on cholinesterase activity in various biological fluids.

A case is presented of a fatal ingestion of Furadan (carbofuran), a cholinesterase-inhibiting carbamate insecticide. A 26-year-old white male was found dead with a partially filled 1-gal (3.8-L) container of Furadan 4F insecticide-nematocide (44.9% carbofuran). The individual had ingested approximately 345 mL of the mixture. Analysis of cholinesterase activity in various biological fluids was performed spectrophotometrically using propionylthiocholine and 5,5'-dithiobis-2-nitrobenzoic acid [Sigma Diagnostics, cholinesterase procedure No. 422 (PTC)] which was measured at 405 nm and 30 degrees C in a Gilford Stasar III Spectrophotometer. The cholinesterase activities were as follows: plasma, 245 units (U)/L (93% inhibition/7% normal activity); serum, 208 U/L (95.3% inhibition/4.7% normal activity); whole blood, 297 U/L (92.8% inhibition/7.2% normal activity); erythrocytes, 58 U/L (99% inhibition/1% normal activity); vitreous humor, 7 U/L; and bile, 148 U/L. Carbofuran was detected in the blood and gastric contents by thin-layer chromatography. No alcohol or other drugs were detected in the blood, urine, or gastric contents. Ingestion of the carbofuran produced acute visceral congestion and pulmonary edema. Death was caused by anoxia due to respiratory paralysis produced by cholinesterase inhibition from Furadan (carbofuran) ingestion.

Adult↗
PubMedDate not supplied

Detection of cholinesterase inhibition. The significance of cholinesterase measurements.

Human cholinesterase exists in two forms--acetylcholinesterase located in tissue microsomes and red blood cells and serum cholinesterase found in serum or plasma. The two enzymes display marked differences in structure, substrate specificity, biological function, and origin. Contemporary methods employ acylthiocholine as substrate for serum cholinesterase and a second coupled reaction of thiocholine and chromogenic disulfide agents. Clinical applications are primarily centered on subnormal levels of enzyme activity. The decreased activity levels can be caused by inhibitors, reduced biosynthesis, or dysfunctional genetic variants. Changes in enzyme activity should be related to baseline levels because there is wide individual variation as well as methodological variation. Once baseline levels have been established, cholinesterase activity becomes a sensitive indicator of pesticide intoxication and hepatic biosynthetic capacity. A more sophisticated assay, performed in the presence of an inhibitor, is required to detect the atypical genetic variants of serum or plasma cholinesterase.

Acetylcholinesterase↗
PubMed1974

Cholinesterases from plant tissue: v. Cholinesterase is not pectin esterase.

Several properties of the cholinesterase from Phaseolus aureus Roxb. and of pectin (methyl) esterases from both Phaseolus aureus and Lycopersicon esculentum (L.) Mill. are contrasted. Cholinesterase activity is inhibited by all of the concentrations of NaCl tested, from 0.05 m to 0.9 m, a property which differs sharply from published data pertaining to pectin esterase. Although crude preparations of cholinesterase contain pectin esterase activity, further purification by gel filtration of the cholinesterase results in a nearly complete elimination of the pectin esterase activity. The activity of neither the pectin esterase from Lycopersicon esculentum nor that from Phaseolus aureus is affected by 25 mum neostigmine, a potent inhibitor of the cholinesterase activity extracted from Phaseolus aureus.

Journal Article↗
PubMed1989

Serum cholinesterase isoenzymes and the WHHL rabbit: the relationship between the activity of cholinesterase not bound to low-density-lipoprotein and lipoprotein titer.

Serum cholinesterase has been previously shown to complex with beta-lipoprotein in the plasma. Since serum cholinesterase exists as isoenzymes in plasma, the relationship between the activity of these isoenzymes (unbound to beta-lipoprotein) and lipoprotein titer was investigated. The results indicated that the total of C2, C3, and C4 isoenzyme activities were expressed within a narrow range and independent of low density lipoprotein titer. These findings may indicate that unbound plasma cholinesterase may undergo autoregulation independent of cholinesterase bound to beta-lipoprotein.

Animals↗
PubMed1989

Additional electrophoretic components of cholinesterase in plasma: a phenomenon of no importance to the total plasma cholinesterase activity.

Total plasma cholinesterase and cholinesterase isozyme components were studied in 193 healthy subjects without occupational exposure to known cholinesterase inhibitors. The study showed that the four additional isozyme components, C5, C1', C6, and C7 occurred in plasma independently of each other, and that the total plasma cholinesterase activity was completely uninfluenced by the presence of any of the four components.

Adult↗
PubMedDate not supplied

[Cholinesterase profile of geriatric patients with reference to pathologically lowered serum cholinesterase].

1. Analysing systematically 416 geriatric patients with a predominance of heart's and circulations's disease and disturbance of mobility we find a pathological lowered cholinesterase in 36% of the cases. This percentage is higher than expected in regard to the hepatological diagnosis. 2. Analysing the histological data of 26 patients with pathological lowered cholinesterase we find with all of them a granular edema of the hepatocyt cytoplasme and intracellular lipofiscin deposit near the central veins. We find also often a diabetic and fat liver. The pathological lowered cholinesterase goes hand in hand with a pathological histology. 3. There is no correlation between the cholinesterase and the other liver enzymes. 4. These results may be interpretated as a sign for a lowered synthesis efficiency of pathological hepatocyts and there are discussed the consequences for the adaptation of the metabolism. A correlation of the years of age corresponding to the theory of deficit in age is not proved.

Adult↗
PubMed1973

Cholinesterases from Plant Tissues: II. Inhibition of Bean Cholinesterase by 2-Isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine Carboxylate Methyl Chloride (AMO-1618).

2-Isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride (AMO-1618) inhibits the activity of a cholinesterase isolated from mung bean (Phaseolus aureus) roots at concentrations comparable to those which retard growth and inhibit development of secondary roots of bean seedlings. Fifty per cent inhibition of the cholinesterase activity occurred at 0.21 mm. Inhibition of the cholinesterase is non-competitive and irreversible. The growth retardant seems to be a specific cholinesterase inhibitor since it has no effect on non-choline esterases.

Journal Article↗
PubMed1981

Brain cholinesterases activity in healthy cattle, swine, and sheep and in cattle and sheep exposed to cholinesterase-inhibiting insecticides.

Cholinesterase activity of the cerebrum, brain stem, and cerebellum was measured in cattle, swine, and sheep. Mean activities of the individual brain parts were expressed as micromoles of acetylthiocholine iodide hydrolyzed per minute per gram of brain. Cerebrum values were 3.01, 3.88, and 3.32; brain stem values were 3.42, 4.48, and 3.93; and cerebellum values were 2.36, 2.89, and 6.77 for cattle, swine, and sheep, respectively. The average activity of the 3 brain portions from cattle, swine, and sheep was 2.93, 3.75, and 4.67, respectively. Cholinesterase activity was stable for several days at 25 C and under refrigeration or freezing conditions for longer periods. Cattle and sheep poisoned with organophosphate or carbamate insecticides had cholinesterase depression ranging from near 50% to 80%.

Animals↗
PubMed1986

Is the peptidase activity of highly purified human plasma cholinesterase due to a specific cholinesterase isoenzyme or a contaminating dipeptidylaminopeptidase?

The peptidase site of human plasma cholinesterase (butyrylcholinesterase) is distinct from its esteratic site. We found that the number of peptidase sites on an enzyme highly purified from pooled plasma is less than 0.1, as compared with 4 esteratic sites, per tetramer. However, the subunits which carry the peptidase sites are electrophoretically indistinguishable from esteratic subunits. The atypical-silent enzyme (Ea1Es1) had a much higher absolute peptidase activity when substance P was used as the substrate, and we found that the number of peptidase and esteratic sites of this enzyme was roughly the same. This suggests that the mutated esteratic site of the silent possesses a peptidase activity. The esteratic site of the usual allozyme (Eu1Eu1) has no peptidase activity towards substance P. However, a small proportion of peptidase subunits are present in all preparations of enzymes purified from the plasmas of homozygote individuals. The peptidase activity of butyrylcholinesterase might therefore correspond to a specific isoenzyme produced by an epigenetic mechanism or produced by a gene distinct from genes E1 and E2 encoding for cholinesterase subunits. However, the possibility that highly purified cholinesterase contains traces of a dipeptidylaminopeptidase cannot be completely ruled out.

Binding Sites↗
PubMed1990

[Cholinesterase in healthy adults. Significance of sex, age, weight and height for activation of P-cholinesterase].

On the basis of an investigation og 193 healthy adults without occupational exposure to known cholinesterase-inhibitors, it was found that in addition to being related to the sex and ChE-fenotype, the cholinesterase activity is correlated to the weight and height of the individual concerned. Compared with the great interindividual variations, the intraindividual variations are of marginal significance for the total variation. Where dissimilar groups are concerned, comparison of the cholinesterase values corrected for variations which may be ascribed to the factors: sex, ChE-fenotype, weight and height is recommended.

Adult↗
PubMed1981

Cholinesterase in the parasitic nematode, Stephanurus dentatus. Characterization and sex dependence of a secretory cholinesterase.

An antigenic secretory protein with cholinesterase activity was isolated from the excretory gland cells of Stephanurus dentatus and was purified by gel filtration and ion exchange chromatography. The antigenicity of the cholinesterase was demonstrated by an esterase-active immunoprecipitate formed with S. dentatus antiserum and by the ability of the antiserum to protect the enzyme from heat inactivation. The enzyme was found to be secreted by the adult nematodes during in vitro cultivation. The level of cholinesterase activity and its release from the excretory gland cells of the parasite were 27-fold greater in the male than in the female. Ninety per cent of the enzyme activity was localized in the soluble fraction of the gland cells. The molecular weight of the enzyme, estimated by sucrose density gradient centrifugation, was 100,000. Two molecular forms were separated by isoelectrofocusing, with isoelectric points of 7.0 and 6.9. At optimum substrate concentrations, the rate of hydrolysis of acetylthiocholine was 8 times greater than that of butyrylthiocholine; the Michaelis constants were 560 microM and 81 microM for acetylthiocholine and butyrylthiocholine, respectively. The enzyme exhibited substrate inhibition at substrate concentrations greater than 10 mM and was inhibited by eserine sulfate, 1,5-bis(4-allyldimethylammoniumphenyl)-pentan-3-one dibromide, Tris, and acetone. The enzyme was highly unstable in dilute protein solutions.

Animals↗
PubMedDate not supplied

[Finding cholinesterase in endotheliocytes: cholinesterase inhibition by organophosphorus compounds leads to endotheliocyte deformation].

Toxic action of some organophosphorus cholinesterase inhibitors (including phosphacol) on the state of microvessels was studied in rats. Cholinesterase was found in endotheliocytes and it was established that phosphacol inhibited this enzyme. This was one of the factors responsible for deformation of the luminal relief of the vessels and for violation of the blood microcirculation. The expression of these effects was different for various organophosphorus compounds.

Animals↗
PubMed1989

Age-determined changes in the effects of a newly synthetized cholinesterase inhibitor on exploratory behavior, memory and striatal cholinesterase activity in rats.

The newly synthetized cholinesterase inhibitor C-8 (a structural analogue of physostigmine) at a dose of 4 mg.kg-1 exerted no inhibitory effect on the spontaneous locomotor activity in 2-, 10- and 22-month old male Wistar rats. Upon open field test, C-8 facilitated the process of habituation in the rats of all three groups. In a passive avoidance situation (step-down and step-through) C-8 had a favorable effect on the memory of 22-month old rats mainly. C-8 inhibited the cholinesterase activity in the striatum of 2-month old rats by 29%, in 10-month old rats by 73%, and in 22-month old rats by 30%.

Aging↗
PubMedDate not supplied

RBC cholinesterase inhibition: a useful surrogate marker for cholinesterase inhibitor activity in Alzheimer disease therapy?

Red blood cell (RBC) acetylcholinesterase (AChE) inhibition has been used as a peripheral surrogate marker for the activity of centrally acting AChE inhibitors (AChEIs) in the treatment of Alzheimer disease. As a valid peripheral surrogate marker, RBC AChE inhibition should reflect the central pharmacodynamic activity of the compound and should demonstrate a relation with cognitive or global improvement in patients with Alzheimer disease. As a useful clinical tool, RBC AChE inhibition should also provide an advantage in dose optimization. However, the application of surrogate markers in research and clinical use is controversial (Prentice, 1989; Gotzsche, 1996; Colburn, 1997; De Gruttola et al., 1997). For instance, surrogate markers that have been identified or applied inappropriately can lead to erroneous conclusions, slowing the drug development process (Colburn, 1997). Also, the validation of surrogate markers for the pharmacodynamic activity of central nervous system drugs is not always possible because samples of brain tissue cannot be analyzed in humans. Finally, although validation of peripheral markers for central nervous system drugs has been approached via analysis of cerebrospinal fluid (Cutler et al., 1998a), few markers have been subjected to such rigorous evaluation in clinical studies. The extent to which measures of peripheral AChE inhibition accurately model central drug activity and therapeutic effectiveness of AChEIs, both as individual agents and as a drug class, is the focus of this review. AChEIs comprise a group of structurally diverse compounds with a wide range of relative specificities for the various molecular species of cholinesterase found in plasma, RBCs, and the brain. Studies of RBC AChE inhibition after administration of AChEIs in animals are of limited utility because of the differential sensitivity of AChEIs for human versus animal forms of AChE, the poor correlation between effective doses in animals and humans, and the lack of standardized measurements of effectiveness. Although clinical studies of donepezil, metrifonate, and eptastigmine have suggested the potential use of RBC AChE inhibition as a predictor of clinical response, the degree of inhibition yielding maximum cognitive improvements was highly variable from compound to compound (30-80%). Further, investigators did not prove a relation between central and peripheral pharmacodynamics or demonstrate an advantage over dose in the ability of RBC AChE inhibition to predict clinical response. A study of rivastigmine in patients with Alzheimer disease revealed that cerebrospinal fluid AChE inhibition correlated well with cognitive performance, whereas peripheral inhibition did not. Therefore, RBC cholinesterase inhibition is not a reliable surrogate marker for the activity of AChEIs as a class of drugs, and its usefulness as a dose optimization tool for individual agents has yet to be demonstrated clearly.

Acetylcholinesterase↗
PubMed1995

Plasma cholinesterase and abnormal reaction to succinylcholine: twenty years' experience with the Danish Cholinesterase Research Unit.

For more than 20 years, the Danish Cholinesterase Research Unit (DCRU) has collected information about patients showing an abnormal response to succinylcholine. The purpose of this study was, on the basis of the 20 years' experiences with the Unit, to evaluate our clinical findings in patients referred because of prolonged response following succinylcholine. Also, we wanted to evaluate the results of our prospective controlled studies of the effect of succinylcholine in patients with normal and abnormal plasma cholinesterase genotypes. An explanation for the apparent abnormal response to succinylcholine was found in 61.1% of the 1,247 patients referred to the Unit. Of the 1,247 patients, 28.5% were genotypically normal and 46.5% had an abnormal genotype. In the remaining 24.9% of the patients, the genotype could not be established. The time to sufficient recovery of neuromuscular function following succinylcholine 1.0-1.5 mg kg-1 was 15-30 min in patients heterozygous for one abnormal gene, 35-45 min in patients heterozygous for two abnormal genes and 90-180 min in patients homozygous for the atypical gene. Patients with two newly discovered genotypes (AK (5 patients) and AH (1 patient) showed slightly prolonged (20 min) and markedly prolonged (90 min) duration of action of succinylcholine, respectively. Our results indicate that it is a problem for many anaesthetists to correctly diagnose a prolonged response to succinylcholine. We therefore urge the anaesthetist always to use a peripheral nerve stimulator when faced with a case of apparent abnormal response to succinylcholine.

Apnea↗
PubMed1981

Cholinesterase Newfoundland: a new succinylcholine-sensitive variant of cholinesterase at locus 1.

A family from Newfoundland was found to have a new rare variant for plasma cholinesterase (E.C.3.1.1.8) recognized by a high-percentage inhibition by dibucaine (DN), particularly when succinyldithiocholine was used as substrate (DNSDTC) but also somewhat high when benzoylcholine was substrate (DNBZCH). The family data demonstrated that the variant is determined by an allele of the usual and atypical alleles at locus 1, and the new allele is designated CHE1*NFLD. The proband who was heterozygous for the Newfoundland and atypical alleles had shown sensitivity to succinylcholine. It is postulated that cholinesterase Newfoundland (NFLD) has a reduced affinity for succinylcholine. Samples selected for high DNs with a benzoylcholine from 200 Canadian Caucasians and 70 Newfoundlanders did not have the variant, and, therefore, it is assumed that the remainder of the samples did not have the variant.

Adult↗
PubMed1996

[Plasma cholinesterase and abnormal reaction to suxamethonium injection. 20-year experience with the Danish Cholinesterase Registry].

For more than 20 years, the Danish Cholinesterase Research Unit (DCRU) has collected information about patients showing an abnormal response to succinylcholine. The purpose of this study was to evaluate our clinical findings in patients referred because of prolonged response following succinylcholine. Also, we wanted to evaluate the results of our prospective controlled studies of the effect of succinylcholine in patients with normal and abnormal plasma cholinesterase genotypes. An explanation for the apparent abnormal response to succinylcholine was only found in roughly 60% of the 1247 patients referred to the Unit. In the remaining nearly 40% of the patients the reason for the abnormal response remained obscure, though our results indicate that the anaesthetic technique, including hyperventilation or central respiratory depression, was most likely to be the reason. The significance of the different genotypes, including two newly discovered genotypes (AK, AH), for the reaction to succinylcholine was evaluated and found to be comparable to previous findings. Our results indicate that it is a problem for many anaesthetists to correctly diagnose a prolonged response to succinylcholine. We therefore urge the anaesthetist to use a peripheral nerve stimulator when faced with a case of apparent abnormal response to succinylcholine.

Cholinesterases↗