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PubMed2002

Variation of esterase electromorphs associated with bloodmeal digestion in phlebotomine sand flies (Diptera: Psychodidae).

Esterases are often used to measure genetic variation, yet they may be influenced by external factors. Isoelectrofocusing was used to investigate the effects of bloodmeal on the esterase variation in wild populations of Phlebotomus (Larroussius) ariasi Tonnoir and P. (L.) perniciosus Newstead and in a colonized population of P. (Phlebotomus) duboscqi Neveu-Lemaire. Modified electrophoretic profiles were demonstrated to be associated with blood digestion. The bloodmeal-induced esterase electromorphs were only found in the abdomen homogenates of the sand flies. These changes in esterase phenotype were probably due to a proteolysis phenomenon and disappeared at the end of bloodmeal digestion. The effect was eliminated by adding trypsin inhibitors.

Animals↗
PubMed1984

Hydrolysis of cholesterol ester in artificial lipid mixtures by cholesterol esterase released from particulate fractions of rat arterial wall.

Acid and neutral cholesterol esterase activities in rat arterial wall were released from the lysosomal fraction and microsomal fraction respectively into the 105,000 X g supernatant fraction by treatment with Triton X-100, heparin and dextran sulfate. The percentage releases of acid cholesterol esterase by Triton X-100 (0.1%), heparin (50 micrograms/ml) and dextran sulfate (1 mg/ml) were 21%, 18% and 4%, respectively, while those of neutral cholesterol esterase were 66%, 56% and 39%, respectively. The cholesterol esterase released by dextran sulfate, especially that from the microsomal fraction, hydrolyzed cholesterol ester in artificial lipid mixtures with similar lipid compositions to those of the deposits in fatty streaks and fibrous plaques of atheromatous lesions.

Animals↗
PubMedDate not supplied

Alpha-naphthyl acetate esterase-1 (ANAE-1) secreted by epithelioid cells from induced rabbit lung granuloma showed MIF activity.

The function of alpha-naphthyl acetate esterase-1, whose isoelectric point values range from 5.15 to 5.45, was examined. A higher value of alpha-naphthyl acetate esterase-1 was detected in the extracts of epithelioid cells isolated from rabbit lung granuloma at 4 weeks after injection of Freund's complete adjuvant, compared to those values of alveolar macrophages isolated from the same lungs described above and of the normal lungs. Additionally, this enzyme activity was observed to be prominent in the culture supernatants of epithelioid cells. alpha-Naphthyl acetate esterase-1 was purified from lung granuloma as a single 62-kDa band by SDS-PAGE analysis. The purified enzyme showed a macrophage migration inhibition activity at concentrations over 20 nM, and its activity was dose-dependent. Moreover, when various amounts of the purified enzyme were added to lymphocyte-derived macrophage migration inhibitory factor, macrophage migration inhibition was significantly enhanced with a dose-dependent manner. The results suggest that alpha-naphthyl acetate esterase-1 secreted by granuloma macrophages, particularly by epithelioid cells, contributes to granuloma formation.

Animals↗
PubMed2000

Biology of monocyte-specific esterase.

The monocyte-specific (carboxyl)esterase (MSE) is a marker enzyme which is well-known to hematologists as its detection is part of the traditional cytochemical stainings of leukemia cells. There are a variety of synonyms for MSE among hematologists and biochemists. Biochemically, MSE is well-characterized, but should be discerned from other esterases with similar or identical substrate specificities and other features. Intensive analysis of normal and malignant hematopoietic cells and leukemia-lymphoma cell lines using isoelectric focusing established the specificity of this enzyme for monocytes and related cells, hence its designation as monocyte-specific esterase. Cloning of the gene led to its molecular characterization and provided new opportunities to examine MSE expression also at the RNA level which confirmed the monocyte/macrophage specificity. The availability of the gene sequences of various serine esterases and lipases which also hydrolyze ester bonds allowed for the identification of identical isolates from different tissues and the construction of an unrooted dendrogram based on sequence homologies of 22 enzymes. The detailed regulation of the gene and the functional role of MSE have remained largely unknown as of yet. However, DNA binding sites for various transcription factors have already been detected. Some evidence suggests involvement in physiological detoxification processes and in the immune defense against tumor cells. A more thorough understanding of the in vivo function of this truly unique enzyme should be helped by characterizing the signals and signal transduction mechanisms which lead to MSE expression.

Biomarkers, Tumor↗
PubMed1993

Segmental differences in drug permeability, esterase activity and ketone reductase activity in the albino rabbit intestine.

Possible segmental differences in drug permeability as well as esterase and ketone reductase activities in the albino rabbit intestine were investigated. Beta adrenergic antagonists and timolol prodrugs spanning four orders of magnitude in distribution coefficient were used as model drugs. Drug penetration was evaluated in Ussing chambers using isolated segments of the duodenum, jejunum, ileum, ascending colon, descending colon, and rectum. Esterase and ketone reductase activities were determined in homogenates of the above segments using timolol ester prodrugs and levobunolol as substrates, respectively. The results indicate that the hydrophilic beta adrenergic antagonists atenolol and sotalol and moderately lipophilic metoprolol penetrated all intestinal segments equally well, whereas moderately lipophilic timolol and lipophilic propranolol, levobunolol and betaxolol were better absorbed from the large than from the small intestinal segments. Changes in lipophilicity exerted a more pronounced effect on the penetration of beta adrenergic antagonists in the large than the small intestinal segments. A similar pattern existed for timolol prodrugs. In addition to segmental differences in drug permeability, segmental differences in esterase and ketone reductase activities also existed. The level of esterase and ketone reductase activities in the small intestinal segments was, on average, 12 times and 5 times higher, respectively, than in the large intestinal segments. The implication of the above findings is that segmental differences in drug permeability and metabolism must be considered in the design of oral drug delivery systems.

Adrenergic beta-Antagonists↗
PubMed1999

Relationship between amount of esterase and gene copy number in insecticide-resistant Myzus persicae (Sulzer).

Overproduction of the insecticide-degrading esterases, E4 and FE4, in peach-potato aphids, Myzus persicae (Sulzer), depends on both gene amplification and transcriptional control, the latter being associated with changes in DNA methylation. The structure and function of the aphid esterase genes have been studied but the determination of their copy number has proved difficult, a common problem with gene amplification. We have now used a combination of pulsed-field gel electrophoresis and quantitative competitive PCR to determine relative esterase gene copy numbers in aphid clones with different levels of insecticide resistance (R1, R2 and R3). There are approx. 4-fold increases between susceptible, R1, R2 and R3 aphids, reaching a maximum of approx. 80 times more genes in R3; this gives proportionate increases in esterase protein relative to susceptible aphids. Thus there is no overexpression of the amplified genes, in contrast with what was thought previously. For E4 genes, the loss of 5-methylcytosine is correlated with a loss of expression, greatly decreasing the amount of enzyme relative to the copy number.

5-Methylcytosine↗
PubMed1976

[Heat stability of cholinesterase and non-specific esterases during development of hybrids of the sea urchins Stongylocentrotus droebachiensis and S. intermedius].

Acetylcholine esterase (AchE) and non-specific esterases were studied during the development of sea urchins Strongylocentrotus droebachiensis and S. intermedius and their hybrids by means of electrophoresis and measurements of enzyme thermostability. Two AchE fractions were found which differed by thermostability. At the late gastrula stage, the therolabile form predominated and at the mid-pluteus stage the thermostable one. Non-specific esterases in both the species of sea urchins are represented by complex isozyme systems. Their changes during development are accompanied by the changes in thermostability and electrophoretic patterns. The thermostability of esterases at the pluteus stage in the hybrids is higher than in the maternal species, apparently, due to the appearance of the thermostable enzyme which appears in the paternal species provisionally at the prism stage.

Acetylcholinesterase↗
PubMed1976

Histochemical study of distribution of esterases in the pharyngeal bulb of earthworms.

The esterases are studied histochemically in the pharyngeal bulb of local earthworms using tweens, naphthols and indoxyl substrates. Lipase and esterases are located mainly in the pharyngeal epithelial cells and chromophill cells. No activity is seen in the nonchromophill cells. The connective tissue and musculo-vascular tissue contain some esterases activity. Possible role of the esterases in the cellular elements of pharynx has been discussed.

Animals↗
PubMed1999

[A preliminary study of developmental genetics of polymorphic serum esterase in domestic fowls].

Polymorphism of serum esterase was examined in 3 Super-Y 2000 broiler breeding populations differing in developmental stages (i.e. day 120, 180 and 300) using vertical polyacrylamide gel electrophoresis. The results indicated that both Es-1 and Es-2 loci exhibited polymorphism. Two to three polymorphic enzyme bands were detected at zone Es-1, and one band at zone Es-2 after electrophoresis. It was first discovered in this work that obvious developmental difference in products of Es-1 alleles existed with female birds, polymorphic bands of which disappeared after onset of lay. An individual tracing experiment conducted in a Super-Y 380 commercial layer population and an extensive experiment carried out in 2 ISA B380 parent CD stocks supported the previous finding. It could thus be inferred that phenotype "O" (no band at Es-1) discovered in hens was not genetically controlled by the recessive allele Es-1(0), which itself did not exist, but might be an evidence of gene regulation at laying period. For female birds, expression of Es-1 alleles was active before sexual maturity, and depressed after onset of lay, to meet their physiological need of high level of blood esterase for laying. It could also be inferred that this developmental difference in serum esterase polymorphism might be a common phenomenon in all avian species. If this hypothesis were true, the synthesis of esterase inside avian bodies could be a desirable model for investigating expression, and regulation of expression, of genes in avian populations.

Animals↗
PubMed2001

Evaluation of the accuracy of leukocyte esterase testing to detect pyuria in young febrile children: prospective study.

OBJECTIVE: To study the accuracy and clinical application of the dipstick leukocyte esterase test in the detection of pyuria in young febrile children suspected to have urinary tract infection. DESIGN: Prospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: Urine samples were taken from 215 children younger than 2 years who were suspected to have urinary tract infection (fever without an obvious focus of infection). MAIN OUTCOME MEASURES: The accuracy of the dipstick leukocyte esterase test in detecting significant pyuria defined as a leukocyte count >or=10 mm(3) (>or=0.01 x 10(9) /L). RESULTS: Two hundred and fifty-four urine samples collected by bag, midstream clean-catch, suprapubic bladder aspiration, or urethral catheterization were examined. Using urine microscopy results as a reference, the sensitivity and specificity of the leukocyte esterase test in detecting significant pyuria were found to be 72.0% and 85.8%, respectively; the positive and negative predictive values were 55.4% and 92.6%, respectively; and the positive and negative likelihood ratios were 5.1 and 0.3, respectively. CONCLUSIONS: The dipstick leukocyte esterase test cannot accurately detect pyuria in young febrile children. It is also not appropriate as a screening test to exclude pyuria, reduce the need for the microscopic examination of urine, or indicate when a hospital admission for probable urinary tract infection is needed.

Esterases↗
PubMed2002

Toxicity testing using esterase inhibition as a biomarker in three species of the genus Lecane (Rotifera).

We have developed an esterase inhibition test to investigate the effects of 10 toxicants, including six metals (cadmium, chromium, copper, lead, mercuric chloride, and titanium) and four organics (benzene, ethyl acetate, toluene, and vinyl acetate) in three species of the benthic rotifer genus Lecane (L. hamata, L. luna, and L. quadridentata). Metals affect esterase inhibition by an average value of 4,957-fold greater than the four organics tested for the three rotifer species. Most of the EC50 (effect concentration where a 50% reduction in esterase activity is observed) values correspond to environmentally realistic concentrations. Comparisons of acute-to-chronic ratios among these three species showed that in two species, L. luna and L. quadridentata, esterase inhibition is an outstanding biomarker for most of the toxicants tested.

Animals↗
PubMedDate not supplied

[Hybridization and genetic control of esterase in apricot].

Inheritance of esterase was studied in nine segregating progenies. It was established that fast migrating components are controlled by two loci, Est-1 (monomeric alpha-esterase) and Est-2 (dimeric beta-esterase). Their polymorphism is determined by three active alleles, a, a', b for Est-1 and a, b, c for Est-2, respectively. Allelic frequencies and heterozygosity of loci in ecological-geographical groups and Central Asian subgroups were estimated. Genetic control of esterase in stone fruits was proposed for the first time.

Alleles↗
PubMed1992

Role of serine esterase in hydrogen peroxide-mediated activation of phospholipase A2 in rabbit pulmonary arterial smooth muscle cells.

Exposure of rabbit pulmonary arterial smooth muscle cells to hydrogen peroxide cause dose-dependent stimulation of [14C] arachidonic acid (AA) release and enhancement of the cell membrane-associated phospholipase A2 activity as well as of the cell membrane-bound serine esterase activity tested against synthetic substrate p-tosyl-L-arginine methyl ester. While pretreatment of cells with serine protease inhibitors, viz. phenyl methyl sulphonyl fluoride, diisopropyl fluorophosphate and alpha-1-proteinase inhibitor, and antioxidant vitamin E prevents H2O2 stimulation of AA release and the cell membrane-bound serine esterase and PLA2 activities, that with actinomycin D and cycloheximide is devoid of any effect on H2O2 caused stimulation of AA release and the smooth muscle cell membrane associated serine esterase and PLA2 activities. Treatment of the smooth muscle cell membrane suspension with the serine protease trypsin markedly stimulates PLA2 activity. These results suggest that on exposure to H2O2 the smooth muscle cell membrane-bound serine esterase plays an important role in stimulating the cell membrane associated PLA2 activity thereby resulting in an increase in AA release.

Animals↗
PubMed1992

The effect of methotrexate (MTX) on the small intestine of the mouse. IV. The Golgi apparatus, phosphatases and esterases.

The Golgi apparatus and alkaline and acid phosphatase and nonspecific esterase activities were studied in the jejunal epithelium of adult male albino mice (Mus musculus) under normal conditions and after MTX treatment. In the control, the Golgi apparatus took the form of rods, spheres and crescents occupying the supranuclear region. After MTX, the Golgi apparatus, in most of the cells, was hypertrophied. In the control cells, alkaline and acid phosphatase and nonspecific esterase activities were moderate and localized supranuclearly, but were intense in the brush border and basement membrane. After MTX, all three enzyme activities increased, with a marked reaction in the brush border and basement membrane. The increase in alkaline phosphatase may mean that more phosphate transport is needed in the active phosphorylation process or in the transfer of MTX macromolecules across the cell membrane, or it may be due to MTX-induced disorganization of metabolism. The increase in acid phosphatase activity denotes an increase in catabolic processes resulting from imbalance of lysosomal function, while the rise in nonspecific esterase activity could be related to fatty acid metabolism, or it might be due to the detoxicant function of esterases. In all control and MTX-treated specimens, the supranuclear concentration of these enzymes coincided with the localization of the Golgi apparatus.

Animals↗
PubMedDate not supplied

[Modification of the method of trypsin esterase activity determination].

Determination of esterase activity of trypsin in blood serum using the Erlanger's method leads to overestimation of enzyme activity due to the increased "dimness" of the reaction medium. V. A. Shaternikov suggested a correction, which is based on the use of the two-wavelength registration method. But this correction does not eliminate this secondary factor completely. So for the clearing of the solutions we offer to stop the reaction by putting tubes into ice followed by subsequent centrifugation the investigated samples at 0 degree C for 15 min, at 25,000 g. It gives the possibility to measure an actual increase of an optical density in accordance to the hydrolysis of the substrate. The results of the measuring of an esterase activity of trypsin are represented in a serum and in a peritoneal exudate of dogs with an acute experimental pancreatitis. The serum esterase activity of trypsin in a was not found in intact animals. Three hours after induction of pancreatitis trypsin activity was detected only in blood serum of two of seven animals [approximately 3.6 mmole/(min-l)]. Rats with acute pancreatitis also had very low esterase activity of trypsin in blood [0.38 +/- 0.16 mmole/(min-l)] that insignificantly deferred from the control. These data question applicability of this method for diagnostics of acute pancreatitis. The estarse activity of trypsin detected in blood and peritoneal exudate, does not indicate its proteolytic activity, because it was insensitive to soybean trypsin inhibitor.

Acute Disease↗
PubMed2004

[Change of lipid, esterase and lipase in mosquito larvae infected with Lagenidium giganteum].

OBJECTIVE: To explore possible physiological and biochemical mechanisms of Lagenidium giganteum infection in killing mosquito larvae. METHODS: The content of lipid and the activities of esterase and lipase between the normal and infected mosquito larvae were observed with histochemical method. The results were photomicrograph and analysed by image analysis using computer. RESULTS: In 24 hrs after infection, the content of lipid in the infected Culex quinquefasciatus larvae was lower while the activities of esterase and lipase in the larvae were higher than the control. In 48 hrs and 78 hrs after infection, the content of lipid in the infected larvae of C. quinquefasciatus and Ae. albopictus were significantly lower while the activities of esterase and lipase were significantly higher than those of control. CONCLUSION: The content of lipid in the mosquito larvae decreased while the activities of esterase and lipase increased after the infection of Lagenidium giganteum. The disorder of lipid metabolism might be part of the killing mechanisms to C. quinquefasciatus and Ae. albopictus larvae.

Aedes↗
PubMedDate not supplied

[Changes in the activity and pattern of hemolymph esterases in the larvae of wax moth Galleria mellonella L. (Lepidoptera, Pyralidae) during mycosis].

The extended pattern of multiple esterase forms has been revealed in the hemolymph of wax moth Galleria mellonella larvae infected by the fungi Metarhizium anisopliae, Beauveria bassiana or Paecilomyces fumoso-roseus. The total esterase activity of the hemolymph also increases during mycosis. Mechanical damage of the cuticle, treatment with deltamethrin, and chilling of the caterpillars induced similar changes in the hemolymph pattern of esterase activity. Presumably, the changed spectrum and activity of the hemolymph esterases during mycosis is due to the damaged cuticle and epidermis cells.

Animals↗
PubMedDate not supplied

Enantioselective hydrolysis of lorazepam 3-acetate by esterases in human and rat liver microsomes and rat brain S9 fraction.

Rates of hydrolysis of racemic and enantiomeric lorazepam 3-acetates (LZA) by esterases in human and rat liver microsomes and rat brain S9 fraction were compared. LZA and its hydrolysis product were analyzed by chiral stationary phase HPLC. When rac-LZA was the substrate, the (R)-LZA was hydrolyzed 2.7-fold and 6.8-fold faster than the (S)-LZA by esterases in rat and human liver microsomes, respectively. In contrast, esterases in rat brain S9 fraction were enantioselective toward the (S)-LZA. The specific activities (nmol of LZA hydrolyzed/mg protein/min) of liver microsomes in the hydrolysis of enantiomerically pure (R)-LZA were approximately 210 (rat) and 1330 (human), and in the hydrolysis of enantiomerically pure (S)-LZA were 25 (rat) and 8 (human). The specific activities of rat brain S9 fraction in the hydrolysis of enantiomerically pure (R)-LZA and (S)-LZA were approximately 3 and 6 nmol/mg protein/min, respectively. Results also indicated an enantiomeric interaction in the hydrolysis of rac-LZA; the presence of (R)-LZA stimulated the hydrolysis of (S)-LZA by all esterase preparations, whereas the presence of (S)-LZA stimulated the hydrolysis of (R)-LZA in rat brain S9 fraction and inhibited the hydrolysis of (R)-LZA in rat and human liver microsomes.

Animals↗