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At least 487 records · Page 27Linked to original sources
PubMed2002

Serum cholinesterase activity correlates with serum insulin, C-peptide and free fatty acids levels in patients with type 2 diabetes.

When compared with values recorded in 14 control subjects, the 15 overweight patients with type 2 diabetes displayed significantly increased activities of serum alanineaminotransferase (172% of mean values in controls), gamma-glutamyltransferase (253%) and cholinesterase (139%). A much wider dispersion of individual values for the two firstly mentioned enzymes was however noted so that their correlation with serum triglycerides levels were weaker (r = 0.373; p < 0.05 and r = 0.451; p < 0.05 respectively) than the same correlation obtained for serum cholinesterase (r = 0.760; p < 0.001). In two other studies including 28 controls and 30 diabetic patients serum cholinesterase was found to be significantly correlated with serum levels of insulin (r = 0.622; p < 0.001), C-peptide (r = 0.652; p < 0.001) and free fatty acid (r = 0.821; p < 0.001). Circumstantial evidence is provided that insulin resistance and an increased flux of free fatty acids from adipose tissue to the liver would stimulate the hepatic synthesis of serum cholinesterase.

Adult↗
PubMedDate not supplied

Impact of pretreatment cholinesterase level on survival of inoperable intrahepatic or hepatic-hilar carcinomas treated with three-dimensional conformal radiotherapy.

PURPOSE: Prognostic factors for inoperable hepatocellular carcinomas (HCC), intrahepatic cholangiocellular carcinomas (IHCC), and hepatic-hilar cholangiocellular carcinomas (HHCC) treated with three-dimensional conformal radiotherapy (3DCRT) were evaluated. MATERIALS AND METHODS: Thirty-five consecutive patients were treated with 3DCRT (HCC, 14; IHCC, 11; HHCC, 10). Doses of 3DCRT ranged from 30-70 Gy (mean, 51.5 Gy). The follow-up time of the 12 living patients was 5-39 (median, 11) months. RESULTS: Two-year overall survival rates of HCC, IHCC, and HHCC were 19%, 26%, and 39%, respectively. On univariate analysis, 3DCRT dose (<50 Gy vs. 50-54 Gy vs. > or =60 Gy) (p<0.01) and pre-3DCRT cholinesterase value (p<0.01) were statistically significant factors for survival. Two-year overall survival rates of the patients treated with <50 Gy, 50-54 Gy, and > or =60 Gy were 0%, 50%, and 17%, respectively. The difference in survival between patients given 50-54 Gy and > or =60 Gy was not statistically significant (p=0.13). Two-year overall survival rates of patients with higher and lower cholinesterase values were 43% and 0%, respectively. On multivariate analysis, the independent variable most predictive of survival was pre-3DCRT cholinesterase value (p<0.01). CONCLUSION: Pre-3DCRT cholinesterase value was a significant independent prognostic indicator for survival. Benefit of dose escalation above 60 Gy could not be demonstrated.

Aged↗
PubMedDate not supplied

[A study of the peripheral quaternary ligand binding site of cholinesterase with the use of ethidium bromide].

The peripheral binding site of horse serum cholinesterase (EC 3.1.1.7) for quaternary ligands was investigated by fluorescent probing with the use of ethidium bromide. Spectral evidence for the participation of the tryptophan indole group of the peripheral site of horse serum cholinesterase in the formation of a cholinesterase complex with ethidium bromide is presented. The mechanism of cholinesterase effect on ethidium bromide fluorescence is proposed.

Animals↗
PubMed1990

Identification of a frameshift mutation responsible for the silent phenotype of human serum cholinesterase, Gly 117 (GGT----GGAG).

A frameshift mutation that causes a silent phenotype for human serum cholinesterase was identified in the DNA of seven individuals of two unrelated families. The mutation, identified using the polymerase chain reaction, causes a shift in the reading frame from Gly 117, where GGT (Gly)----GGAG (Gly+ 1 base) to a new stop codon created at position 129. This alteration is upstream of the active site (Ser 198), and, if any protein were made, it would represent only 22% of the mature enzyme found in normal serum. Results of analysis of the enzymatic activities in serum agreed with the genotypes inferred from the nucleotide sequence. Rocket immunoelectrophoresis using alpha-naphthyl acetate to detect enzymatic activity showed an absence of cross-reactive material, as expected. One additional individual with a silent phenotype did not show the same frameshift mutation. This was not unexpected, since there must be considerable molecular heterogeneity involved in causes for the silent cholinesterase phenotype. This is the first report of a molecular mechanism underlying the silent phenotype for serum cholinesterase. The analytical approach used was similar to the one we recently employed to identify the mutation that causes the atypical cholinesterase variant.

Amino Acid Sequence↗
PubMed1986

Contamination of highly purified human serum cholinesterase by dipeptidyl peptidase IV causing hydrolysis of substance P.

The purification and kinetic characterization of cholinesterase from blood plasma (pseudocholinesterase; butyrylcholinesterase: EC 3.1.1.8) is described. The hydrolysis of the artificial peptide substrate Lys-Pro-p-nitroanilide served as a model of the second step in degradation of substance P by dipeptidyl peptidase IV. The substrate is hydrolyzed by a gel-electrophoretic homogeneous cholinesterase preparation with a reaction rate of 5.8 mumol/min X mg and a KM value of 0.12 mmol/l. The proteolytic reaction could not be affected with typical cholinesterase inhibitors NaF and dibucain. On the other hand Lys (pNO2-Z)-Pro and a specific suicide substrate (diacylhydroxylamine derivative) inhibit the activity in a manner analogous to dipeptidyl peptidase IV. Though these active site-directed inhibitors also influenced the benzoylcholine hydrolyzing activity of serum cholinesterase, we conclude from the data that dipeptidyl peptidase IV was the true Lys-Pro-p-nitroanilide cleaving activity. Furthermore, the conclusion can also be drawn that hydrolysis of substance P reported by Lockridge 1982 is caused by the contamination that cannot be completely separated from the esterase during the purification method used.

Cholinesterases↗
PubMed1979

[Effect of LSD-25 on cholinesterases of the rat brain].

The indications for investigation on the LSD-25 "in vivo" activity on brain cholinesterases of the rat, have been considered. Indications of materials and method used have been supplied too. From the results obtained it emerged no clear evidence of a statistically significant inhibition of cholinesterases due to LSD-25. The results have been discussed and it has been evidenced that the lack of action of the psychotomimetic substance on cholinesterases could be only apparent or that the discrepancy between the LSD-25 anticholinesterase "in vivo" and "in vitro" action should be ascribed to the too scarce tissue levels which can be reached with the does utilized. Apart from the hypothesis, tending to explain the results obtained, it has been considered that the LSD-25 behavioural action, is not probably carried out thanks to a cholinesterase activity.

Animals↗
PubMed1987

[Phenotype of plasma cholinesterase in prolonged apnea and sensitivity to succinylcholine].

90% of the injected dose of succinylcholine is hydrolysed by serum cholinesterase (E.C.3.I.I.8) Abnormal variants of serum cholinesterase lead to prolonged apnea. This report presents the results of 62 serum cholinesterase phenotyping including 12 cases of prolonged apneas. One clinical case of prolonged apnea in a patient homozygous for the atypical cholinesterase gene is presented with a study of his genealogy. The phenotypes were established on the basis of dibucaïne, fluorure, chloride and propranolol differential inhibition. The frequency and significance of the various phenotypes is discussed.

Anesthesia, General↗
PubMed1986

Molecular biology of human serum cholinesterase.

More than 90% of the amino acid sequence of purified human serum cholinesterase has been determined in our laboratory. Purified enzyme was digested with several proteolytic enzymes; the resulting polypeptides were then separated, purified, and sequenced. Optimal sequence regions were identified and used as the basis for the synthesis of three 17-mer oligonucleotide probes. In addition, one long peptide of 58 amino acid residues was selected for construction of two unique sequence oligonucleotide probes of 39-mer and 53-mer; the peptide regions corresponding to the latter are six amino acids apart. The probes have been used to screen a human liver cDNA library and a human genomic library. Several positive clones to both types of probes have been identified. These are being characterized, and some of them have been or are now being sequenced. A high degree of homology in the amino acid sequence of the active center of human serum cholinesterase and that of acetylcholinesterase from the Torpedo fish has been noted. It appears that this region of cholinesterases has been conserved during evolution, and there may be an important, still unrecognized role for serum nonspecific cholinesterase in mammalian metabolism.

Amino Acid Sequence↗
PubMed1985

Total cholinesterase in plasma: biological variations and reference limits.

Factors affecting biological variation in total cholinesterase activity in plasma were studied in a population of 3372 apparently healthy subjects at least four years old. Determination of the dibucaine number, after inhibition of the activity by dibucaine, made it possible to specify the contributions of genetic and physiological characteristics to variations in the total activities by using a statistical method of segmentation. The main factors modifying plasma cholinesterase activity in males are genetic status (dibucaine number) and degree of overweight (subscapular skinfold). In females, hormonal status (puberty or menopause), genetic status (dibucaine number), and the use of oral contraceptives are the factors mainly responsible for the variations of plasma cholinesterase activity. These data allow us to propose reference limits for total plasma cholinesterase.

Adolescent↗
PubMed1973

Effect of sample storage on human blood cholinesterase activity after inhibition by carbamates.

During an operational field trial with propoxur it was observed that the inhibition of whole blood cholinesterase was greater when samples were stored before the assay. Since measurement of cholinesterase activity is not always possible immediately after sampling, the effects of different storage conditions were evaluated. Human blood cholinesterases were inhibited in vitro by methylcarbamates and stored at different pH values, temperatures, and sample dilutions. The results showed that the degree of cholinesterase inhibition does not change if samples are diluted 300-fold with buffer at pH 5.0 at 4 degrees C and the enzyme activity measured within 4 hours after dilution. These conditions of storage were equally satisfactory for each of the three methylcarbamates studied and are therefore likely to apply to other carbamates as well.

Carbamates↗
PubMed1971

Comparative aspects of the purification and properties of cholinesterases.

Recent years have seen great progress in the purification and characterization of cholinesterases. Investigation has indicated the existence of two principal groups: a fairly homogeneous group of acetylcholinesterases and a group of enzymes that utilize butyrylcholine, propionycholine, or benzoylcholine as substrates and that differ widely in their properties.This paper reviews the different types of cholinesterase and their sources, the importance of a proper choice of substrate in cholinesterase studies, methods for the purification of cholinesterases, and some of the properties of these enzymes.

Acetates↗
PubMed1978

Comparison of atypical and usual human serum cholinesterase. Purification, number of active sites, substrate affinity, and turnover number.

Atypical and usual human serum cholinesterases were purified and studied with the fluorescent probe, N-methyl-(7-dimethylcarbamoxy)quinolinium iodide. Four active sites per tetramer were found in each enzyme. The turnover numbers of usual and atypical cholinesterases were the same: 15,000 mumol of benzoylcholine hydrolyzed/min/mumol of active site; 48,000 min-1 for o-nitrophenylbutyrate; and 0.0025 min-1 for N-methyl-(7-dimethylcarbamoxy)quinolinium iodide. They had identical rate constants for carbamylation, (5.0 min-1) and for decarbamylation (0.15 h-1). The major difference between the two genetically determined forms of the enzyme was substrate affinity, KD being 0.16 mM for usual and 5.4 mM for atypical cholinesterase, for the fluorescent probe substrate. Km for the uncharged ester, o-nitrophenylbutyrate, was 0.14 mM for both enzymes, whereas Km for benzoylcholine was 0.005 mM for usual and 0.024 mM for atypical cholinesterase. We interpret these data to mean that the two enzymes differ only in the structure of their anionic site.

Binding Sites↗
PubMed1978

The protective effects of ethylestrenol against acute poisoning by organophosphorus cholinesterase inhibitors in rats.

Pretreatment of rats with 10 mg of ethylestrenol (17alpha-ethylestr-4-en-17beta-ol) by force feeding twice daily for three days and once on the fourth day decreased the severity of parathion (0,0-diethyl 0-4-nitrophenyl phosphorothioate) toxicity and caused a 150% increase in the parathion LD50 in male animals. It decreased by 51% cholinesterase inhibition in the brain caused by i.p. injection of 2 mg of parathion/kg body weight but not that of an equitoxic dose (0.5 mg/kg) of its active metabolite, paraoxon (0,0-diethyl 0-4-nitrophenyl phosphate). It decreased by 29% cholinesterase inhibition in plasma following i.p. administration of parathion but caused only a 16% decrease in cholinesterase inhibition following administration of the equitoxic dose of paraoxon. It did not protect against brain cholinesterase inhibition by 4 mg/kg of parathion given i.v.; however, brain parathion levels were 16% lower in rats pretreated with ethylestrenol than in control rats. It increased the rate of inactivation of both parathion and paraoxon by liver microsomal enzyme preparations. Thus enzyme induction seems to account for the protection afforded by ethylestrenol to toxicity following poisoning by organophosphates.

Animals↗
PubMed1981

Cholinesterases and postnatal development of the negative chronotropic effects of acetylcholine in albino rats.

The negative chronotropic effects of acetylcholine were studied in the isolated atria of the hearts of albino rats aged 2, 15, 29 and 47 days and adult. In untreated preparations, i.e. with full cholinesterase activity, the strongest effects were observed in newborn animals; with advancing age the reaction grew weaker. If cholinesterase activity was inhibited with physostigmine, the differences between the various age groups were obliterated. It is thus evident that the actual acetylcholine sensitivity of the sinoatrial node tissue does alter during postnatal life, but that growing cholinesterase activity reduces the amount of acetylcholine diffusing from the medium into the acetylcholine receptor zone. The change which takes place in cholinesterase activity in the myocardial tissue during postnatal life is so great that is must be taken into account when considering the development of cholinergic control of cardiac function.

Acetylcholine↗
PubMedDate not supplied

[Effect of exogenous acetyl group acceptors on cholinesterase biosynthesis in Arthrobacter simplex cells].

The presence of active acetyl or butyryl groups and their acceptors in the growth medium was found to be necessary for the high rate of cholinesterase biosynthesis in the cells of Arthrobacter simplex var. cholinesterasus. The active acetyl and butyryl groups are formed upon hydrolysis of acetylcholine and butyrylcholine as well as in the course of glucose metabolism. The following acids were shown to be the acceptors of the acetyl and butyryl groups: butyric, succinic, fumaric, malic acids and, to a less extent, alpha-ketoglutaric acid. The active acetyl and butyryl groups are bound with the acceptors under the control of coenzyme A in the reactions of fatty acid synthesis and the tricarboxylic acid cycle. Presumably, CoA regulates cholinesterase synthesis. The high rate of CoA binding in metabolic reactions provides conditions for the intensive synthesis of cholinesterase; the deceleration of these reactions inhibits the biosynthesis of cholinesterase.

Acetylation↗
PubMed1980

[Histochemical study of the cholinesterase activity in the structures of the rat heart normally and during exposure to a pulsed electromagnetic field].

Histotopography and activity of true and false cholinesterases in the non-inbred white rat hearts, normal and at the effect of pulsed electromagnetic field (80 kA/m) have been demonstrated by Karnovsky-Roots histochemical method. It has been stated that a single 6 hours' application of the pulsed electromagnetic field results in an increased cholinesterase activity in all cardiac structures, besides neurocytes. If the application is continued, cholinesterase activity is progressively decreasing and its minimum is observed on the 10th day of the stimulation. From the 15th day on, increasing enzymatic activities are observed, various for different enzymes: that of acetylcholinesterase even by the 30th day of the stimulation by the magnetic field does not reach the normal level, while that of cholinesterase exceeds this level. Mast cells are noted to appear along the cholinergic neural fibres. A suggestion is made on possible exchange between them by mediator acetylcholine. Electrocardiographic data have demonstrated that certain correlation exists between acetylcholinesterase activity and the cardiac function.

Acetylcholinesterase↗
PubMed1977

Cholinesterase activity in the microfilaria of Wuchereria bancrofti Cobbold.

The distribution of cholinesterase activity in the microfilaria of the nocturnally periodic Wuchereria bancrofti has been described. Using histochemical methods, cholinesterase activity has been demonstrated in the amphids (Mundgebilde), phasmids (Schwanzgebilde), nerve-ring, excretory and anal vesicles of the microfilaria. It has been found that the enzyme activity disappeared completely after treatment with the specific cholinesterase inhibitor eserine. Evidence is presented that the greater amount of the cholinesterase activity detected is related to acetylcholinesterase and the functional significance of the enzyme in the enzyme reactive structures is discussed.

Acetylcholinesterase↗
PubMedDate not supplied

[Behavior of serum and erythrocyte cholinesterase in experimental tetanus in rabbits].

In rabbits injected i.m. with 1 MLD of tetanus toxin, the levels of the serum cholinesterase and of the erythrocytic cholinesterase were determined twice every day, during the course of the intoxication, until the death of the animals. The levels of the serum cholinesterase were decreasing day by day, while these of the erythrocytic cholinesterase did not show any significant variation. These results are strictly comparable to those one may observe in organophosphorus poisoning.

Animals↗