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PubMed1989

[Differential diagnosis in the preliminary evaluation of esterase responses of tongue coating cells].

The tongue coating cells were stained by Alpha-naphthol acetate esterase and naphthol AS-D chloroacetate esterase in 100 patients with different symptom-complex [five groups: dampheat, damp-heat due to blood stasis, Yin deficiency, Yang deficiency and Qi-blood deficiency] in view of TCM, and in 116 healthy persons. The responses of the epithelial cells of the tongue and the leukocytes to the two esterase stainings were observed. The results were: the number of nonspecific esterase was much higher in the patients, especially in the patients with Yin or Qi-blood deficiency, than that in the healthy persons (P less than 0.001); responses to ASDCE suggested that the leukocytes of the patients were different from those of the healthy persons in classification, more granulocytes in the healthy persons, and increased proportion of monocytes and lymphocytes in the patients, the most increased proportion of monocytes in the patients with Qi-blood deficiency and the most increased proportion of lymphocytes in the patients with Yang deficiency. The mechanisms of the different responses to the two esterase stainings in the patients and healthy persons, and the relationship between these mechanisms and the symptom-complexes by TCM were discussed.

Adolescent↗
PubMed1988

Quinidine-induced decrease of intracellular esterase activity in a hepatoma cell line.

Using image-analyzing equipment, we measured the effect of quinidine on the activity of naphthol AS-D chloroacetate esterase, alpha-naphthyl butyrate esterase, alpha-naphthyl acetate esterase, and acid phosphatase in individual cells of a human Hep G2 hepatoma cell line. The impact of the drug on the morphology of the cells was also observed. Depending on the concentration of quinidine applied, various changes occurred, the most extreme being cell death. However, at some drug concentrations that did not appear to affect visible cell structures, the activity of the esterases was decreased. This lessened enzyme activity did not seem to be related to the enzymes leaking from the cells, because the activity of acid phosphatase was unaffected. Inhibition of the esterase activity was related to the interval of exposure to quinidine in the perfusing medium and to the concentration of the drug. We consider the system described here to be a potential replacement for experiments with animals in the study of hepatotoxicity.

Animal Testing Alternatives↗
PubMed1985

Activation of myocardial neutral triglyceride lipase and neutral cholesterol esterase by cAMP-dependent protein kinase.

Lipolysis of intracellular triglycerides in the heart has been shown to be regulated by hormones. However, activation of myocardial triglyceride lipase in a cell-free system has not been directly demonstrated. In the present studies, initial attempts to demonstrate cAMP-dependent activation of triglyceride lipase using the 1,000 X g supernatant fraction (S1) of mouse heart homogenate were unsuccessful, presumably due to the masking effects of high levels of lipoprotein lipase activity even when assayed at pH 7.4 and in the absence of apolipoprotein C-II. Myocardial lipoprotein lipase in the 40,000 X g supernatant fraction was then removed by heparin-Sepharose affinity chromatography. The lipoprotein lipase-free fractions were shown to contain neutral triglyceride lipase and neutral cholesterol esterase of about equal activities. The triglyceride lipase and cholesterol esterase activities fell progressively during preincubation in the presence of 5 mM Mg2+. Additions of cAMP and ATP resulted in 40-70% activation of both triglyceride lipase and cholesterol esterase. The activation was blocked by protein kinase inhibitor and was restored by the addition of exogenous cAMP-dependent protein kinase. Since lipoprotein lipase has no activity toward cholesteryl oleate, activation of cholesterol esterase in untreated S1 was readily demonstrable. Both triglyceride lipase and cholesterol esterase activities were present in homogenates prepared from isolated rat heart myocytes. We conclude that the myocardium contains a hormone-sensitive lipase that is regulated in a fashion similar to that of the adipose tissue enzyme.

Adenosine Triphosphate↗
PubMed1988

The nitrite and leukocyte esterase tests for the evaluation of asymptomatic bacteriuria in obstetric patients.

The purpose of this investigation was to compare the reliability of a urine dipstick evaluation for nitrites and leukocyte esterase activity with that of a urine culture in diagnosing asymptomatic bacteriuria in obstetric patients. A clean-catch midstream urine specimen was obtained from 750 consecutive obstetric patients presenting for initial evaluation. One portion of the specimen was tested for nitrites and leukocyte esterase activity with Chemstrip LN dipsticks. A second aliquot of urine was plated on blood and MacConkey agar and incubated aerobically. The cost of the nitrite and leukocyte esterase test was $0.35. The per patient charge for the urine cultures would have been $28. Sixty-two women (8.3%) had urine cultures of 100,000 or more colony-forming units of a uropathogen per milliliter. The sensitivities of the nitrite and leukocyte esterase test in identifying patients with positive cultures were 43 and 77%, respectively, and the specificities were 99 and 96%, respectively. The sensitivity and specificity for the two tests combined (either test abnormal) were 92 and 95%, respectively. Five patients had negative screening tests but positive urine cultures; all five isolates were gram-positive organisms, three group B streptococci and two enterococci. We conclude that neither the nitrite test nor the leukocyte esterase test alone is a sensitive enough screening test to detect asymptomatic bacteriuria in obstetric patients. The combination of the two tests, however, may provide an acceptable cost-effective alternative to screening all asymptomatic obstetric patients with urine cultures.

Bacteriuria↗
PubMed1988

Quinidine-induced inhibition of leukocyte esterases.

We have demonstrated the feasibility of a system based on image processing to measure enzyme activity inside morphologically classified individual cells. When used in this system, quinidine inhibited naphthol AS-D chloroacetate esterase in polymorphonuclear neutrophils and alpha-naphthyl acetate esterase and alpha-naphthyl butyrate esterase in monocytes. These effects were dependent on the duration of exposure and on drug concentration. Dose-effect relationships were established and the concentration at which 50% inhibition (ID-50) occurred was used as a reference point to compare the toxicity of different compounds. Chloroquine, primaquine, and quinine (which, like quinidine, possess a quinoline ring) also affected the esterases, but had no effect on several other enzymes. Neostigmine inhibited the esterases we studied but only at a very high concentration. Various chemicals inhibited the enzymes within the cells, as has been demonstrated for the enzymes in plasma.

Animal Testing Alternatives↗
PubMed1987

Genetic association between highly active esterases and organophosphate resistance in Culex tarsalis.

The genetics of two highly active esterases, A3H and B3H, in a methyl parathion-resistant strain (MP-R) of Culex tarsalis was investigated in relation to organophosphate (OP) resistance. The increased activity of esterase A3 and of esterase B3 is under the control of two distinct and closely linked (approximately 4.4 centimorgans) genes. Each gene possesses two forms, one controlling high activity (A3H or B3H, respectively) and one controlling low activity (A3L or B3L, respectively) of the enzymes. Organophosphate resistance in the MP-R strain is strongly associated with the presence of these highly active esterases. The results are discussed in relation to the present knowledge on the mechanisms responsible for high activity of esterases observed in other OP-resistant mosquitoes of the genus Culex.

Animals↗
PubMedDate not supplied

Detection of leukocyte esterase in urine: a new screening test for nongonococcal urethritis compared with two microscopic methods.

First-catch urine samples of 130 men attending a clinic for genitourinary medicine were screened with the leukocyte esterase dipstick test. Conventional microscopy of centrifuged sediment and inverted microscopy of unspun urine samples were performed 2-4 hr later. The leukocyte esterase test had sensitivities of 100% and 96.6% and specificities of 55% and 52.8%, respectively, when compared with the two microscopic methods. The apparently low predictive value of the positive leukocyte esterase test was probably linked to its ability to detect lysed cells and the limitations of the microscopic methods, which were used as the absolute indicator of nongonococcal urethritis. Of the 42 patients with microscopic pyuria, 45.2% had positive cultures for Chlamydia trachomatis, and the leukocyte esterase test was positive in every case. Twenty-one per cent of the C. trachomatis-positive patients were asymptomatic, and 42% had fewer than five polymorphonuclear leukocytes per high-power field (X1000) of the gram-stained urethral smear. The leukocyte esterase test appears to be a simple, practical, and sensitive test that is useful in screening for nongonococcal urethritis, especially asymptomatic nongonococcal urethritis.

Esterases↗
PubMed1979

Nonspecific esterases in normal human blood cells: characterization of isoenzymes by isoelectric focusing in polyacrylamide gel.

Using the high resolution technique of isoelectric focusing in polyacrylamide gel, isoenzymatic components of nonspecific esterase were resolved in esterase-rich extracts obtained from normal human monocytes, lymphocytes, granulocytes and platelets. In the case of each cell type, different isoenzymatic patterns of nonspecific esterase activity could be visualized. These studies extend the cytochemistry of nonspecific esterases by detection of previously undescribed isoenzymatic components, and suggest that the elaboration of nonspecific esterase isoenzymes may be a function of cellular differentiation.

Blood Cells↗
PubMed1981

Nonspecific esterases of the formed elements: zymograms produced by pH 9.5 polyarcrylamide gel electrophoresis.

The formed elements of human blood each contain multiple isoenzymes of nonspecific esterase that hydrolyze short chain alpha naphthyl esters. Zymograms that are characteristic of each type of formed element are obtained by subjecting purified preparations of each to polyacrylamide slab gel electrophoresis at pH 9.5 and subsequent staining of the gels for esterase activity. The most prominent isoenzyme detected is a species of low mobility that is reactive with either acetyl or butyryl esters and is highly sensitive to inhibition by 40 mM sodium fluoride. Also detected are several major acetyl esterases and a single butyryl esterase, all of which are relatively fluoride resistant. The intercellular distribution of isoenzymes varies from element-specific to pancellular. The prominent fluoride-sensitive acetyl, butyryl esterase, is the major isoenzyme of monocyte zymograms, which is consistent with the well known cytochemistry of monocytes. Lesser but significant amount (2%-3% of monocyte levels) of this isoenzyme were also detected in granulocyte zymograms. This system may prove useful in the study of differentiation of blood cells and in the classification of acute leukemias.

B-Lymphocytes↗
PubMed1982

[Esterase polymorphism and heat resistance of the interphalangeal muscle of the common frog].

A study has been made of the electrophoretic esterase spectrum of m. interphalangealis of the grass frog and the heat resistance of this muscle. Vertical electrophoresiss in polyacrilamid gel revealed the enzyme polymorphism in the zone of high electrophoretic mobility. In zone Est.-2, two esterase isoenzymes were detected which was assumed to be the site of genetic control of one locus with two codominant alleles. It is shown that under the standard environmental conditions, there exists a relation between the presence of esterase isoenzymes in m. interphalangealis and the heat resistance of this muscle: the isoenzyme of the slow esterase is present in highly resistant muscles, both isoenzymes are present in muscle with the average resistance level, and the isoenzyme of quick esterase occurs in muscles with different levels of resistance.

Alleles↗
PubMed1981

Optimization and validation of assays to estimate pancreatic esterase activity using well-characterized micellar solutions of cholesteryl oleate and tocopheryl acetate.

Studies have been carried out to determine the maximal solubilization of cholesteryl oleate and tocopheryl acetate within mixed bile salt-fatty acid micelles and to establish reproducible assays for pancreatic esterase activity using these micellar substrates. At pH 8.5, using 30 mM sodium taurocholate and 10 mM oleic acid, reproducible micellar solutions of the esters could be prepared giving micellar concentrations of 0.4 mM and 0.1 mM for tocopheryl acetate and cholesteryl oleate, respectively. Conditions were then optimized to estimate pancreatic esterase activity using these micellar-solubilized substrates. Maximal activity was obtained at pH 8.5 with 2-4 mM oleic acid and 15-30 mM sodium taurocholate, and gave coefficients of variation for the assays of 7.4% and 20.2% using tocopheryl acetate and cholesteryl oleate, respectively, as substrates. Micellar-solubilized cholesteryl oleate and tocopheryl acetate, together with a non-micellar system using p-nitrophenyl acetate, were used to estimate esterase activity in human duodenal aspirates and rat pancreatic homogenates. Esterase activity in children with cystic fibrosis was greatly reduced and paralleled tryptic and pancreatic lipase activity, which suggested that the esterase activity was pancreatic in origin. The results of this study, therefore, provide a basis for future investigations concerned with the hydrolysis and absorption of dietary esters.

Animals↗
PubMedDate not supplied

[Stereospecific action of organothiophosphate amino acid derivatives on nervous system esterase activity in the cockroach].

The effect of optic isomers of Rp- and Sp-CH3(C2H5O)P(O)SCH2C(O)NHCH5-COOC2H5(EH-13), Rc- and Sc-(C2H5O)2P(O)SCH2C(O)NHCH (i-C3-H7)COOC2H5.(SH.-156), RpRc-, SpSc-, and SpRc-CH3(C2H5O)P(O) SCH2C(O)NHCH(i-C3H7)-COOC2H5(Sh.-142) on the fraction composition of esterases from the nervous tissue of American cockroach was investigated. Esterases were separated by polyacrylamide gel disc-electrophoresis. Sp-(EH-13) and Rc-(Sh.-156) were shown to inhibit carboxy esterase to a greater extent than their antipodes. Stereoisomers of the substance (Sh.-142) were found to influence activity of carboxy esterase molecular forms in a different way. It is postulated that the active surface of molecules of certain carboxy esterase isoenzymes may have stereospecific structure.

Amino Acids↗
PubMed1980

Age and blood pressure related changes in cholesterol esterase activity and cholesterol content in aortas of stroke prone spontaneously hypertensive rats, spontaneously hypertensive rats and normotensive Wistar Kyoto rats.

Changes in aortic lipolytic enzyme activities (cholesterol esterase and lipoprotein lipase) and acid phosphatase activity during aging were investigated in three strains of rats with different blood pressures; stroke prone spontaneously hypertensive rats (SHRSP), spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKR). The blood pressures of male, 7 month old animals, was 234 (SHRSP), 173 (SHR) and 128 (WKR) mmHg. The cholesterol esterase activity markedly decreased with age in the aortas of SHRSP, SHR and normotensive WKR rats, while acid phosphatase activity decreased only slightly, if at all, and lipoprotein lipase activity remained unchanged. This effect was enhanced by increasing blood pressure in SHRSP, SHR and WKR. The total aortic cholesterol content increased significantly with hypertension in a inverse relation with cholesterol esterase activity. These results suggest that cholesterol deposition in aged arteries is, at least partialy, ascribable to an age-related decrease in cholesterol esterase, and that hypertension aggravates the deposition of arterial cholesterol by accelerating the age-related decrease in aortic cholesterol esterase activity.

Acid Phosphatase↗
PubMed1993

Biochemical characterization of flestolol esterase.

The blood esterase that mediates the metabolism of flestolol, an ultra short-acting beta blocker, was characterized. Esterase activity occurred in plasma of human, dog, rat, and guinea pig and not in erythrocytes of the same species. The esterase activity was greatest in humans and guinea pigs followed by dogs and rats. Purified human serum cholinesterase was very active against flestolol while human serum albumin was slightly active. Human and bovine erythrocyte membrane acetylcholinesterases, electric eel acetylcholinesterase, human hemoglobin, dog, rat, chicken, and bovine serum albumin were all inactive. Esterase activity with flestolol was inhibited in human, dog, and rat blood by echothiophate, eserine, and sodium fluoride. Guinea pig blood esterase activity was inhibited by echothiophate and sodium fluoride, but not by eserine. Metabolic interaction studies indicated that succinylcholine, procaine, and chloroprocaine interfere with the metabolism of flestolol in human blood. Succinylcholine prolonged the in vitro half-life of flestolol in dog blood, but acetylcholine, procaine, and chloroprocaine had no effect. Flestolol did not affect the metabolism of procaine or chloroprocaine in human and dog blood. The metabolism rate of flestolol decreased in individuals with atypical, fluoride-resistant and silent forms of serum cholinesterase.

Animals↗
PubMed1977

Comparison of the esterase and human plasminogen activator activities of various activated forms of human plasminogen and their equimolar streptokinase complexes.

A comparison was made of the esterase and activator activities of the various activated forms of human plasminogen and their streptokinase complexes with Nalpha-Cbz-L-lysine-p-nitrophenyl ester as the substrate. The steady state kinetic properties of Glu- and Lys-plasmins, and Glu- and Lys-plasminogen-streptokinase complexes were identical, while the Lys-plasmin-streptokinase complex showed a 2-fold increase in Km with the same kcat and a 3-fold increase in Ki for the competitive inhibitor leupeptin. Lys-plasminogen (zymogen with an active site) was prepared which incorporated 0.7 mol of [3H]idisopropyl phosphorofluoridate and 0.43 mol of p-nitrophenyl-p'-guanidinobenzoate/mol of protein. The Km for Lys-plasminogen was 3-fold higher than that of Lys-plasmin, and its maximum velocity 10-fold lower. The steady state kinetic parameters of a plasmin-derived light (B) chain (CmCys)3, and a derived equimolar light (B) chain-streptokinase complex (CmCys)3, isolated from human plasmin and equimolar plasmin-streptokinase, or plasminogen-streptokinase, complexes, respectively, were determined. When the light (B) chain-streptokinase complex is isolated from its parent complexes, there is a complete retention of the original parent's esterase activities, with respect to Km and kcat, and interaction with the competitive inhibitors benzamidine and leupeptin. The plasmin-derived light (B) chain does not retain its parent esterase activities. This chain has very similar kinetic properties to Lys-plasminogen except that streptokinase, in an equal molar amount, does not impart full esterase activity to the light (B) chain whereas the zymogen can be completely activated by streptokinase. The kcat of the plasmin-derived light (B) chain, and its streptokinase complex can be enhanced by 50 and 30%, respectively, in the presence of 10(-4) M leupeptin, a competitive inhibitor of plasmin, attesting to the increased structural flexibility within the active site of this enzyme species. Urokinase hydrolyzes Nalpha-Cbz-L-lysine p-nitrophenyl ester efficiently with a kcat/Km of one-third that of plasmin. The human plasminogen activator activities of various activated forms of human plasminogen and their equimolar streptokinase complexes were compared in a kinetic assay. The Lys-plasmin-streptokinase complex, and streptokinase were the least active of the activator species and were approximately equal in their activator activities. Glu- and Lys-plasminogen-streptokinase complexes had approximately 1.5 times the activity of streptokinase, whereas the equimolar light (B) chain-streptokinase complexes had approximately 2- to 3-times the activator activity of streptokinase. Since the esterase activity remained unchanged, this indicates a greater degree of specificity in the active site of the equimolar light (B) chain-streptokinase activator complex. Urokinase proved to be a poor activator species...

Enzyme Activation↗
PubMed1996

Gender differences in toxicokinetics, liver metabolism, and plasma esterase activity: observations from a chronic (27-week) toxicity study of enalapril/diltiazem combinations in rats.

Diltiazem (DTZ), a calcium channel blocker, and enalapril (EN), an angiotensin-converting enzyme inhibitor, are being developed as combination therapy for cardiovascular disease. A toxicokinetic evaluation of EN and DTZ drug levels during a 27-week toxicity study used an enzyme assay to measure EN and an HPLC assay to measure DTZ, deacetylated DTZ (DAD), and desmethyl DTZ (DMD). EN exposure during drug week 7 was proportional to dose and without dispositional gender differences. However, gender differences in DTZ and metabolite plasma profiles were dramatic. For example, female DTZ Cmax values were roughly 15-20% of males; DAD plasma Cmax values were roughly 3- to 10-fold greater; and the desmethyl metabolite, DMD, was roughly 2- to 10-fold lower. Sodium fluoride added to samples taken during drug week 26 to inhibit plasma esterase activity did not alter DTZ plasma profiles, suggesting that gender differences in DTZ and metabolite plasma levels were not caused by sample degradation. Liver esterase activity in treated rats was significantly greater (p > 0.05) than controls, whereas plasma activity was not affected. Female plasma and liver esterase activities were roughly 3- and 5-fold greater than males (p < 0.002), respectively, which may explain the low DTZ and high DAD plasma levels we measured. These results indicate that liver and plasma esterase activity is much greater in female rats and may be responsible for the differences in drug and metabolite plasma profiles relative to males. In addition, chronic coadministration of EN/DTZ may modestly increase liver esterase activity.

Animals↗
PubMed1998

Hydrophobilization of an esterase by genetic combination with polyproline at the carboxyl terminal

Polyproline, which is an amphiphilic polypeptide, was incorporated into the carboxyl terminal of an esterase by the recombinant DNA technique. The hydrophobicity of the esterase increased with increasing chain length of polyproline without inducing significant conformational changes. The mutant esterase catalyzed the hydrolysis of long-chain carboxylic acid ester more efficiently than the native esterase. It is considered that the alteration of substrate specificity is due to enhanced access of the mutant esterases to hydrophobic substrates. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1997

Purification and characterization of juvenile hormone esterase from hemolymph of the Colorado potato beetle.

In the Colorado potato beetle (Leptinotarsa decemlineata), low juvenile hormone (JH) titers are necessary to initiate metamorphosis and diapause. Low JH titers coincide with high activities of JH esterase, which occur mainly in the hemolymph. The specific activity of JH esterase appeared to be highest in the last larval instar, at day 3 after the molt, and reached a value of 13.5 nmol/min/mg. JH esterase was purified from hemolymph collected at this stage be a sequence of separation systems, including preparative nondenaturing PAGE, isoelectric focusing, and SDS-PAGE. The enzyme had a molecular weight of 120,000 and was composed of two subunits with molecular weights of 57,000, which were not linked by disulphide bridges. Isoelectric focusing revealed two forms of the enzyme with isoelectric points of 5.5 and 5.6. The Km and kcat of the purified enzyme were determined. The major form with pl 5.6 had a Km of 1.4 x 10(-6) M and a kcat of 0.9 s-1 and the minor form with pl 5.5 had a Km of 2.2 x 10(-6) M and a kcat of 1.9 s-1. The quaternary structure of L. decemlineata JH esterases, as differs from JH esterases in other species, which are monomers.

Animals↗