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At least 865 records · Page 48Linked to original sources
PubMed1977

Acid esterase in human lymphoid cells and leukaemic blasts: a marker for T lymphocytes.

A non-specific acid alpha-naphthyl-acetate esterase activity was investigated in human lymphoid cell populations from tonsils, blood, thymus and in different leukaemias. Four patterns have emerged. (i) The vast majority of T lymphocytes (peripheral blood, tonsils) showed a localized, intense reaction product ("T-like"). (ii) A thymocyte subpopulation expressed faint, localized enzyme activity ("Thy-like) but the majority of thymocytes showed no esterase activity. Some cells from acute lymphoblastic leukaemias with thymocyte surface characteristics had a "Thy-like" appearance. (iii) Most B lymphocytes and cells from chronic lymphocytic leukaemias were esterase negative. No activity was seen in mitogen activated peripheral blood T and B lymphoblasts from peripheral blood and in leukaemic blasts from the common form of childhood acute "lymphoblastic" leukaemia. (iv) Myeloid cells, including peripheral blood monocytes, and blast cells from acute myeloblastic and chronic granulocytic leukaemias showed an intense, diffuse reaction product (M-like). It is concluded that the modified esterase technique is a convenient marker for small mature human T lymphocytes in tissue sections and smears. It may also be helpful in the differential diagnosis of acute lymphoblastic leukaemia with T characteristics, the common form of acute "lymphoblastic" leukaemia and acute myeloblastic leukaemia.

Diagnosis, Differential↗
PubMed1995

Methicillin-resistant Staphylococcus aureus subtyping: interest of combined antibiotyping and esterase electrophoretic typing.

Ninety-four methicillin-resistant Staphylococcus aureus isolates (MRSA) were characterized by means of two typing methods, antibiotyping and esterase electrophoretic typing. Antibiotyping, recorded on the basis of susceptibility testing of 13 antimicrobial agents, allowed the description of 18 antibiotypes, four of which comprised 30, 14, 14 and 12 strains respectively. Esterase electrophoretic typing, based on esterase activity against seven synthetic substrates after polyacrylamide-agarose gel electrophoresis, led to the description of 12 electrophoretic types, two of which were predominant with 60 and 20 strains respectively. The combined use of both typing methods yielded 32 combinations, three of which were predominant with 21, 12 and 11 strains respectively. A good differentiation of strains was achieved, particularly when the antibiotype was correlated to the electrophoretic type. Thus, the combination of antibiotyping with esterase electrophoretic typing may be proposed as a well-suited method for the characterization of MRSA strains.

Bacterial Typing Techniques↗
PubMed1976

Isoenzymes of acid phosphatase and non-specific esterases in cultures of neoplastic and normal tobacco tissues.

Axenic cultures of normal, habituated and crown gall teratoma were grown under varying conditions to examine the effects of environment on the expression of neoplastic character. Acid phosphatase patterns on polyacrylamide gels did not vary greatly among tissues although there were differences in acid phosphatase activity between various strains of Agrobacterium tumefaciens, the bacteria which cause crown gall. Certain esterase isoenzymes were found only in tissues grown on specific media, while others were tissue-specific but independent of the nature of the medium. Comparisons of liquid and solid grown cultures revealed that culture conditions also influence esterase expression. Both sunflower and tobacco crown gall tissue contained an esterase not found in habituated or normal tissues, and similar in electrophoretic mobility to an esterase found in extracts of the bacteria that had induced the tumors. The basic difference between the three tissue types studied is the manner in which they respond to a given environment.

Acid Phosphatase↗
PubMed1975

A preliminary genetic interpretation of the esterase isozymes of human tissues.

1. The esterase isozymes of human tissues have been investigated using the technique of starch-gel electrophoresis. Conventional naphthyl-azo dye linked stains and new fluorogenic staining methods were used to detect the isozymes. 2. Multiple isozymes were identified in every tissue and they were characterized in terms of their electrophoretic mobility, tissue distribution, developmental changes in utero, substrate specificity, inhibition properties and molecular weight. On these criteria 13 sets of esterase isozymes were identified, in addition to the esterase isozymes due to cholinesterase and carbonic anhydrase. 3. The data suggest that the 13 sets of isozymes are determined by at least nine different structural gene loci. 4. No electrophoretic variants were identified in a limited population survey of post-mortem tissues from adults and foetuses, except for the previously described esterase D (ESD) phenotypes.

Electrophoresis, Starch Gel↗
PubMed1990

Monoclonal antibodies allow precipitation of esterasic but not peptidasic activities associated with butyrylcholinesterase.

Commercially available and affinity-purified butyrylcholinesterases isolated from human serum were examined for their esterasic activity and their ability to hydrolyze various neuropeptides, including neurotensin, substance P, and leucine-enkephalin. The three pools that displayed the lowest esterasic activities were shown to hydrolyze neurotensin with the same HPLC degradative pattern. By contrast, noticeable qualitative and quantitative discrepancies were observed when hydrolyses of substance P and leucine-enkephalin by these three butyrylcholinesterase pools were studied. The pool that exhibited the highest esterasic activity appeared to be homogeneously constituted by 90- and 180-kDa protein bands by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and was totally unable to hydrolyze these three neuropeptides. This suggested that the three other butyrylcholinesterase preparations could be contaminated by exogenous peptidases. This was confirmed by means of three distinct monoclonal antibodies directed toward human serum butyrylcholinesterase. The three IgG-purified fractions precipitated the esterasic activity, whereas they failed to precipitate the neuropeptide-hydrolyzing activities whatever the substrate examined. Altogether, these results demonstrate that peptidases associated with butyrylcholinesterase are contaminating enzymes that cannot be considered as intrinsic activities of this enzyme.

Amino Acid Sequence↗
PubMed1993

Esterase from the oil-degrading Acinetobacter lwoffii RAG-1: sequence analysis and over-expression in Escherichia coli.

The est gene encoding an esterase from Acinetobacter lwoffii RAG-1 was cloned into E. coli under the control of the PL promoter of the phage lambda. The N-terminal sequence of the first 20 amino acids of the heterologous expressed esterase corresponded to that obtained from the nucleotide sequence. Antibodies prepared against the over-expressed recombinant esterase in E. coli were used to locate the enzyme primarily in the membrane fractions of A. lwoffii RAG-1. Comparison with homologous proteins from both eukaryotic and prokaryotic organisms suggest that the RAG-1 esterase exhibits sequence motifs characteristic of both serine proteases and of lipases.

Acinetobacter↗
PubMed2001

Induction of cutinolytic esterase activity during saprophytic growth of cucurbit pathogens, Fusarium solani f. sp. cucurbitae races one and two (Nectria haematococca MPI and MPV, respectively).

Cutins from fruit of Cucurbita maxima and Cucurbita moschata cultivars, apple and a C(16) alcohol (hexadecanol) were used to induce cutinolytic esterase activity during saprophytic growth of strains of the two cucurbit pathogens, Fusarium solani f. sp. cucurbitae, race 1 (Nectria haematococca mating population (MPI) and F. solani f. sp. cucurbitae, race 2 (MPV). Four strains of MPV and 11 strains of MPI were were included in the study. Although we were primarily interested in the two cucurbit pathogens (MPI and MPV), six strains of the pea pathogen F. solani f. sp. pisi (MPVI) were included to provide a comparison since most of the knowledge on cutinase activity in N. haematococca has come from a study of that group. Cutinolytic esterase was induced in all strains from both MPV and MPVI but was not detected in any of the 11 strains from MPI regardless of the induction conditions. The amount of cutinolytic esterase activity induced in the MPV strains differed according to the strain and both the source and the amount of cutin used in the induction medium. Information on the influence of cutin source and pH on the induction of cutinolytic esterase activity during saprophytic growth of strains from MPV demonstrates that the gene is regulated differently from that in MPVI.

Carboxylesterase↗
PubMed1978

Presence of alpha-naphthyl acetate esterase activity in human haematopoietic cell lines and in fresh biopsy specimens of lymphoma and myeloma.

We have previously shown that non-proliferating human T- but not B-lymphocytes contain demonstrable amounts of acid alpha-naphthyl acetate esterase (ANAE). The usefulness of this histochemical marker for the diagnosis and classification of malignant lymphoid tumors was investigated by use of a panel of established normal and malignant human haematopoietic cell lines and fresh biopsy cells from malignant lymphomas and myelomas. The results showed that not only the T-cell derived acute leukaemia lines, but also histiocytic lymphoma and myeloma lines and some of the lymphoma (Burkitt and lymphocytic) and non-neoplastic lymphoblastoid cell lines with B-cell surface markers expressed strong ANAE reactivity. Some but not all of the immunoglobulin producing myeloma and lymphocytic lymphoma biopsies were ANAE-positive. Inhibition experiments with sodium fluoride and E-600 demonstrated that although the T-lymphocyte specific esterase is predominantly of 'A'-type, the malignant lines contain also non-specific 'B' esterase and pseudocholinesterase. As the presence of the various esterases did not demonstrate any specific distribution pattern among he haematopoietic cell lines of different origin, we concluded that the ANAE marker is no longer T-specific when malignant lymphoid cells are considered, and that the usefulness of this marker in routine diagnostic work therefore is limited.

B-Lymphocytes↗
PubMed1990

Presence of alpha-naphthyl acetate esterase enzymes in dental and oral epithelium of guinea pig embryos.

This study examines the distribution of alpha-naphthyl acetate esterase enzymes in reduced enamel epithelium, i.e., post secretory ameloblasts (PSA) and external cells of reduced enamel epithelium (ERE) of continuously growing incisor and molar tooth germs and in the covering oral epithelium (OE). Jaws of guinea pig embryos, 25-50 days of gestation age, were pretreated, frozen, serially cut, and incubated with alpha-naphthyl acetate as substrate and hexazotized pararosaniline as capture agent for demonstration of enzyme activity. In addition, sections were preincubated with various inhibitors of enzyme activity. A strong enzyme reaction, essentially unaffected by pretreatment procedures, was demonstrated in all cells of PSA and ERE, and in suprabasal cells of OE. Preliminary characterization of the alpha-naphthyl acetate esterase enzymes by means of inhibitors suggests a prevailing presence of B-esterase enzymes in both oral and dental epithelia. PSA were selectively stained when 2 x 10(-3) M arsanilic acid was used as inhibitor, ERE were selectively inhibited by 10(-5) M eserine, and cells of OE were selectively stained when 2 x 10(-3) M HgCl2 was used as inhibitor. We therefore conclude that the alpha-naphthyl acetate esterase enzymes in combination with inhibitors may serve as histochemical markers for discrimination of dental and oral epithelium in the guinea pig prior to eruption of teeth.

Ameloblasts↗
PubMed1988

Function of granule perforin and esterases in T cell-mediated reactions. Components required for delivery of molecules to target cells.

Cognate T cell-mediated functions require antigen and MHC-restricted recognition of target cells. T-effector functions comprise the delivery of signals for help, for suppression, or for cell death of the target cell. In the case of the delivery of cytotoxicity and of help for B-cell antibody production, it is known that the secretory apparatus of the effector cell participates. Prior to secretion, many components of the effector cell are stored in cytoplasmic granules. Among the important and apparently constant constituents of granules are pore-forming proteins (perforins) and proteinases (granzymes). The putative role of perforin has been thought to mediate direct cytotoxicity. It is postulated here that, in addition, perforin at low concentrations may induce target-cell endocytosis through the formation of Ca channels. Localized endocytosis of the target at the contact site in turn may lead to the uptake of locally secreted effector-cell factors, such as cytotoxic factors (CTL), lymphokines (helper cells), or suppressor factors (suppressor cells). The potential importance of such a mechanism is the delivery and uptake of secreted effector-cell components into the endosomes of target cells, bypassing the need for appropriate target-cell receptors. Perforin thus may subserve two functions depending on its intragranular concentration: one, as a killer molecule, and two, as a delivery system for additional granule factors. One of the roles of esterases in T cell-mediated cognate-effector functions may be to allow recycling of the effector cell. This apparently is achieved by an active process of detachment of the effector T cell from the target cell, possibly by way of the proteolytic cleavage of adhesion molecules. Esterases are secreted, together with perforin and other factors, during granule release at the effector target-contact site, where they can cleave intercellular adhesion molecules and thus allow effector-cell recycling and attachment to new target cells. Other roles of esterases, not discussed here, may include participation directly in the cytotoxic process through uptake into the target cell. The evidence for a common intercellular molecular delivery mechanism of cognate effector T-cell function involving perforin and esterases is summarized. This concept represents a unifying hypothesis for MHC-restricted, contact-requiring, intercellular T cell-signal delivery as well as for the delivery of cytotoxicity by non-MHC-restricted T cells and natural killer cells.

Animals↗
PubMed1972

Enterochelin system of iron transport in Escherichia coli: mutations affecting ferric-enterochelin esterase.

Three mutant strains of Escherichia coli have been isolated which are lacking ferric-enterochelin esterase activity. This enzyme catalyzes the hydrolysis of the enterochelin moiety of ferric-enterochelin to yield ultimately three molecules of N-2,3-dihydroxybenzoylserine. The mutants (designated fes(-)) were shown to be unaffected in enterochelin biosynthesis, capable of enterochelin-mediated iron uptake, and able to utilize ferric-dihydroxybenzoylserine complexes normally. When grown under iron-deficient conditions, however, they showed an absolute requirement for added iron or citrate, a phenotype characteristic of mutants defective in some part of the enterochelin system of iron uptake. These results support the theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase. The three fes(-) strains were shown to be affected in the B component of enterochelin esterase. The fesB gene which is probably the structural gene coding for component B of the esterase, was shown to be located at about minute 14 on the E. coli chromosome together with seven other genes involved in the enterochelin system of iron transport.

Benzoates↗
PubMed1982

Evaluation of leukocyte esterase activity as a rapid screening technique for bacteriuria.

Microscopy and leukocyte esterase activity, both employed as screening techniques for urine cultures, were evaluated with respect to two distinct populations, male and female. When 424 urine specimens from males were examined, 95% of the Gram-stained smears and 91% of the leukocyte esterase tests correctly correlated with culture results, indicating significant bacteriuria. There were no significant differences between the Gram stain and leukocyte esterase activity in predicting a negative culture: 99% and 98%, respectively. Neither microscopy nor esterase activity proved as sensitive or as efficient in predicting a negative culture with the female population.

Bacteriuria↗
PubMed1996

Serotyping and esterase typing for analysis of Listeria monocytogenes populations recovered from foodstuffs and from human patients with listeriosis in Belgium.

Listeria monocytogenes strains isolated in Belgium from different foodstuffs and in sporadic cases of human listeriosis were analyzed. The distribution of serovars differed in each of these populations. The bacteria isolated from cheeses and from human patients with listeriosis were further studied by esterase typing. The twenty esterase patterns defined were not equally distributed in these two populations. The secretion of the virulence determinant phosphatidylinositol-specific phospholipase C and the pathogenicity level of strains in immunocompromised mice could not explain the unequal distribution of esterase types. The discrimination index of esterase typing (DI = 0.868) was compared with that of serotyping (DI = 0.666) and with that of the two combined methods (DI = 0.899).

Animals↗
PubMed1989

Influenza C virus esterase: analysis of catalytic site, inhibition, and possible function.

The active site serine of the acetylesterase of influenza C virus was localized to amino acid 71 of the hemagglutinin-esterase protein by affinity labeling with 3H-labeled diisopropylfluorophosphate. This serine and the adjacent amino acids (Phe-Gly-Asp-Ser) are part of a consensus sequence motif found in serine hydrolases. Since comparative analysis failed to reveal esterase sequence similarities with other serine hydrolases, we suggest that this viral enzyme is a serine hydrolase constituting a new family of serine esterases. Furthermore, we found that the influenza C virus esterase was inhibited by isocoumarin derivatives, with 3,4-dichloroisocoumarin being the most potent inhibitor. Addition of this compound prevented elution of influenza C virus from erythrocytes and inhibited virus infectivity, possibly through inhibition of virus entry into cells.

Amino Acid Sequence↗
PubMed1985

Leucocyte esterase-nitrite screening method for pyuria and bacteriuria.

The value of the one minute leucocyte esterase-nitrite chemical strips as a screening procedure for detecting appreciable levels of pyuria and bacteriuria was assessed by comparison with microscopy and culture results. The likelihood that a negative leucocyte esterase result indicated less than 10 white cells/cu mm by microscopy (the negative predictive value), was 90.1% and that a negative nitrite result indicated less than 10(5) organisms/ml was 91.3%. There were many false positive results with both tests, however, and the overall predictive value of a positive leucocyte esterase or nitrite test, or both, was low. The leucocyte esterase-nitrite strip was neither sufficiently sensitive nor specific enough to be used as a cost effective method for screening urines in the laboratory.

Bacteriuria↗
PubMed1990

Monocyte esterase deficiency in malignant neoplasia.

A survey of the incidence of monocyte esterase deficiency in 4000 inpatients (including 808 with malignant neoplastic disease) and 474 normal controls was performed using an automated esterase method. A highly significant excess of patients with malignant disease and the deficiency was evident when compared with normal controls or all other patients. Within the group of patients with malignant disease the demonstrable excess occurred in B chronic lymphocytic leukaemia, non-Hodgkin's and Hodgkin's lymphoma, and carcinoma of the gastrointestinal tract. There was also a significant excess of patients with the deficiency attending the renal unit, both among patients who had had renal transplants and those who had not. A familial incidence of monocyte esterase deficiency was found in 19 (35%) of first degree relatives of those patients in whom family studies were done. It is suggested that the reason for the increased prevalence of the anomaly in these disorders might be that the diminution of esterase activity has a role in their development.

Esterases↗
PubMed1976

Comparative zone electrophoresis of esterases of Staphylococcus species isolated from mammalian skin.

The electrophoretic mobilities of non-specific esterases in vertical polyacrylamide slab gels were determined for 184 strains of staphylococci, representing a total of 18 proposed species and subspecies. Markedly uniform esterase patterns were seen within species demonstrating a high degree of human host specificity, while those species demonstrating a wide host range were polytypic and often showed considerable polymorphism. The unique banding patterns found in several species indicate that this technique may serve as a valuable aid to existing taxonomic schemes. Starch gel electrophoresis of representative strains usually produced sharper esterase bands than were found with polyacrylamide electrophoresis. However, the additional molecular-sieving effect produced by the polyacrylamide gels differentiated esterases to a greater extent.

Animals↗
PubMed1991

Cholesterol esterase in preglomerular microvessels from normal and cholesterol-fed rabbits.

Feeding cholesterol to rabbits produces an atherosclerotic model sharing common metabolic features with the disease in humans, including the vascular lipid accumulation. In coronary vascular cells, this lipid accumulation has been associated with decreased prostacyclin (PGI2) biosynthesis and acid cholesterol esterase activity. Unlike the coronary vascular bed, renal microvasculature appears relatively resistant to atherosclerotic injury. This study examined whether renal microvessels from cholesterol-fed rabbits demonstrated similar metabolic changes in coronary vascular cells. Rabbits were fed either a 0% or 2% cholesterol diet for 1 mo. Similar to coronary vascular cells, in renal microvessels from cholesterol-fed rabbits PGI2 biosynthesis decreased and tissue concentrations of cholesterol and cholesteryl esters increased. However, unlike coronary vascular cells, renal microvascular cholesterol esterase activity increased. Light and electron microscopy revealed sporadic lipid deposits in renal microvessels from cholesterol-fed rabbits and no foam cells or occlusive lesions. In vitro addition of prostanoids to normal renal microvessels had no effect on cholesterol esterase activity. It is inviting to speculate that the increased acid cholesterol esterase activity in renal microvessels from cholesterol-fed rabbits protected them from developing extensive microvascular lesions. These biochemical events may explain the relative resistance of human renal microvessels to the development of occlusive atherosclerotic microvascular lesions.

Animals↗