Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eosinophil granule major basic protein (MBP) and neutrophils have each been implicated in the inflammatory late phase events of allergic disease. Based on this association and flow cytometric evidence presented in this report for MBP binding to neutrophils, we examined the ability of MBP to activate human neutrophils. Incubation of neutrophils with 0.5 to 3.0 microM MBP at room temperature produced a concentration-dependent chemiluminescence (CL) response that peaked after 50 to 70 min. Reduced-and-alkylated MBP, eosinophil cationic protein, and eosinophil-derived neurotoxin did not induce CL. MBP-induced CL was abrogated in the absence of Ca2+ and was absent in neutrophils isolated from two individuals with chronic granulomatous disease. MBP also stimulated release of superoxide anion (O2-) and lysozyme but not beta-glucuronidase or lactate dehydrogenase. Additionally, 1.5 microM MBP in combination with FMLP or platelet-activating factor stimulated a synergistic increase in O2- release from cytochalasin B-treated neutrophils. The degree of synergism with FMLP or platelet-activating factor was inversely related (p less than 0.005) to the level of MBP-induced O2- release. These results indicate that MBP activates neutrophils in a noncytolytic fashion and provide evidence that eosinophil-neutrophil collaboration may contribute to the pathogenesis observed in allergic late phase reactions.
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PMID:Noncytotoxic activation of neutrophils by eosinophil granule major basic protein. Effect on superoxide anion generation and lysosomal enzyme release. 217 May 21

The role of tyrosine kinases in the responses of human neutrophils to chemotactic factors was examined using the recently described inhibitor erbstatin. Pre-incubation with erbstatin decreased the amount of tyrosine phosphorylation induced by the formylated oligopeptide formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) without effecting the binding of [3H]-fMet-Leu-Phe. Erbstatin also dose-dependently inhibited the production of superoxide anion induced by fMet-Leu-Phe and platelet-activating factor, but did not affect the oxidative burst induced by either the calcium ionophore A23187 or the phorbol ester phorbol 12-myristate 13-acetate. Furthermore, erbstatin diminished the cytosolic acidification elicited by fMet-Leu-Phe, platelet-activating factor, and leukotriene B4. In contrast, erbstatin was without effect on the increase in the levels of cytoplasmic free calcium and polymerized actin elicited by fMet-Leu-Phe, C5a, leukotriene B4 and platelet-activating factor, whereas the increase in cytoplasmic free calcium elicited by platelet-derived growth factor was inhibited by erbstatin. In addition, erbstatin affected neither the release of elastase stimulated by these agonists nor the release of beta-glucosaminidase, lysozyme or vitamin B12-binding protein induced by fMet-Leu-Phe. These results indicate that tyrosine protein kinases are involved in the signaling pathways employed by chemotactic factors in the stimulation of selective functional responses (and superoxide production in particular) in human neutrophils.
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PMID:Selective inhibition of human neutrophil functional responsiveness by erbstatin, an inhibitor of tyrosine protein kinase. 217 35

High activity of proinflammatory, type II phospholipase A2 (PLA2) was found in synovial fluids (SF) in inflammatory arthritis. In search for the sources of this PLA2, we cultured human articular chondrocytes and cartilage explants from healthy, osteoarthritic and rheumatoid joints. All cultures, unstimulated by cytokines, released PLA2 extracellularly. Cultures obtained from the deep layers of the cartilage released more PLA2 than those obtained from the superficial layers. Deep layer explants released 0.38 to 18.16 pmol/min/mg protein PLA2/day, whereas superficial layer explants released 0.39-3.18 pmol/min/mg/day. Chondrocyte cell cultures continuously released PLA2, in the first day 909-46347 pmol/min/(10)6 cells and after 9-26 days of culture 166-2115 pmol/min/10(6) cells. PLA2 released from chondrocytes was calcium dependent and had optimum activity at pH 7.5. Cycloheximide markedly inhibited its release. Chondrocyte cultures also released muramidase (LZM) but there was no correlation between PLA2 and LZM release. It may be concluded that cytokine unstimulated human articular chondrocytes synthesize and release PLA2 extracellularly which is similar to that found in the SF. Thus, chondrocytes may possibly serve as one of the sources of intraarticular PLA2.
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PMID:Synthesis and release of phospholipase A2 by unstimulated human articular chondrocytes. 225 99

The mechanism for binding of human erythrocyte calpain I to human erythrocyte inside-out vesicles was studied by immunoelectrophoretic blot analysis. Binding of calpain I to inside-out vesicles was observed both in the absence and presence of Ca2+. Moreover, in the absence of Ca2+, acidic proteins like casein, ovalbumin and calpastatin suppressed while basic proteins like arginase and lysozyme did not affect the binding of calpain I to inside-out vesicles. Here, we propose a model for the binding of calpain to the membrane.
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PMID:Factors influencing the binding of calpain I to human erythrocyte inside-out vesicles. 228 76

A micro-method for the semi-quantitation of surface-bound horseradish peroxidase (HRP) was developed and was applied to study the competition between ligands of glycosyltransferases and HRP for binding sites on the surface of HeLa cells. Dried coverslip cultures of HeLa cells, fixed in methanol, were placed on 0.3 ml of the incubation medium on parafilm and were incubated for 45 min at 37 degrees C. The incubation medium contained HRP, lysozyme and Ca2+ in HEPES buffer, pH 7.2. After washing, the cells were incubated for 60 min at 37 degrees C in HEPES buffer containing 20 mM Ca2+. After this treatment, the plasma membranes showed a strong cytochemical reaction for HRP. Most of the HRP was released into buffer solution during a 5 h incubation at 37 degrees C in the absence of Ca2+, and was measured by spectrophotometry. The addition of 20 mM Ca2+ to the buffer solution prevented the release of most of the HRP from the plasma membranes thus showing that the binding of HRP required Ca2+. Ligands of glycosyltransferases were added to the incubation medium with HRP. The amount of HRP released from the cells decreased in relation to the competing potency and concentration of these ligands. The method was applied to estimate the concentration of some ligands of galactosyltransferase and sialyltransferase that caused a 50% decrease in the release of previously-bound HRP. CMP-neuraminic acid and gangliosides showed a higher competing potency to the surface binding of HRP than UDP-galactose and chitotriose. The spectrophotometric analysis was correlated (on duplicate samples) with cytochemical observations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Competition between ligands of glycosyltransferases and horseradish peroxidase for binding sites on intracellular and plasma membranes of HeLa cells. Application of a micro-method for the semi-quantitation of surface-bound HRP. 228 14

Human polymorphonuclear leukocytes (PMNs) exhibited a time-dependent (0 to 60 min) increase in the release of lysozyme and lactate dehydrogenase (degranulation) when exposed to a static (direct current) magnetic field of 0.1 Tesla. When 1 X 10(6) PMNs were treated with the calcium channel antagonists diltiazem, nifedipine, and verapamil before exposure to a magnetic field, no significant change in degranulation was detected compared to control and sham-exposed PMNs that were similarly treated. Likewise, magnetic field-induced inhibition of cell migration was prevented with the addition of these antagonists. Such changes in degranulation and cell migration occurred in a dose-dependent manner. These results indicated that these agents protected PMNs exposed to a magnetic field, and the damage to the cells that is mediated by magnetic field-stimulated Ca2+ influx might be preventable. In this regard, pharmaceutical agents might prove useful in protection against injurious electromagnetic field exposure.
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PMID:Use of calcium channel antagonists as magnetoprotective agents. 232 Jul 22

The production of delta-toxin is supposed to be responsible for various pathophysiological effects during infection with Staphylococcus aureus. We compared the effects of delta-toxin with the structurally related bee venom toxin melittin on granulocyte functions and inflammatory mediator release. Delta-toxin and melittin induced a rapid Ca2+ influx, as was shown by fluorescence detection. Furthermore, oxygen radical production, as determined by luminol-enhanced chemiluminescence, was triggered by delta-toxin (0.15 to 15 micrograms/ml), whereas melittin showed only marginal effects. Release of lysozyme and beta-glucuronidase was observed only at high concentrations of 15 micrograms of melittin and delta-toxin per ml. Preincubation (15 min) of neutrophils with both toxins resulted in the formation of 3H-platelet-activating factor (3H-PAF) from 3H-lyso-PAF. After 5 min of incubation, the exogenously added lyso-PAF was converted to PAF (delta-toxin, 80 +/- 2%; melittin, 27 +/- 12% of total radioactivity; n = 3, mean +/- standard error of the mean) and 1-O-alkyl-2-acyl-glycerophosphorylcholine (alkyl-acyl-GPC) (corresponding values, 20 +/- 3% and 51 +/- 14% of total radioactivity). The newly generated PAF was rapidly metabolized to lyso-PAF and alkyl-acyl-GPC during the subsequent incubation period of 60 min. In the absence of any toxin, no formation of PAF from lyso-PAF was observed. Further studies indicated that the metabolism of PAF into lyso-PAF and alkyl-acyl-GPC was inhibited in the presence of delta-toxin. Melittin had no significant effects on PAF metabolism. Neither delta-toxin nor melittin modulated the uptake of PAF and lyso-PAF significantly. Our data provide evidence that delta-toxin has an effect on the activity of neutrophil granulocytes with regard to its proinflammatory capacity.
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PMID:Effect of Staphylococcus aureus delta-toxin on human granulocyte functions and platelet-activating-factor metabolism. 234 Nov 70

Crystals of the calcium-containing lysozyme from horse milk have been grown by precipitation with sodium phosphate. The crystals are orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 53.2, b = 57.1, and c = 38.2 A and contain a single molecule in the asymmetric unit. The crystals are suitable for high resolution x-ray structural analysis.
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PMID:Crystallization of a calcium-binding lysozyme from horse milk. 239 4

The L1 antigen is a highly immunogenic protein of about 36,500 daltons that can be purified from granulocytes with good yield. Immunocytochemistry with a rabbit anti-serum raised against L1 showed it to be present in the cytoplasm of virtually all resting peripheral neutrophils and monocytes. Moreover, immunofluorescence staining demonstrated variable expression of L1 on the plasma membrane of both these cell types, usually along with lysozyme. This indicated that L1 represents a secretory product like lysozyme as their coexpression on the surface of vital cells was contrasted by the absence of lactoferrin. Cytoplasmic L1 was well preserved by both precipitating and cross-linking fixatives, the latter being preferable to avoid leaching out of antigenic material and to obtain good cellular morphology. Thus, fixation for 3 minutes at room temperature in glutaraldehyde (1%)-formaldehyde (3%) afforded excellent immunoperoxidase staining, particularly when a calcium-containing buffer was used. L1 was not found in eosinophilic granulocytes or in resting B- and T-lymphocytes. Neither did blast transformation of lymphocytes seem to induce L1 expression.
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PMID:Distribution of a new myelomonocytic antigen (L1) in human peripheral blood leukocytes. Immunofluorescence and immunoperoxidase staining features in comparison with lysozyme and lactoferrin. 240 91

The ability of thapsigargin and thapsigargicin to activate mast cells and leukocytes has been investigated. The thapsigargin-induced histamine release from rat peritoneal mast cells was found to be dependent on the concentration of thapsigargin, the purity of the mast cell preparations, and the number of mast cells in suspension. Thapsigargin induced histamine release from human basophil leukocytes. Thapsigargin induced beta-glucuronidase and lysozyme release from human neutrophil leukocytes. Thapsigargin caused a release of histamine from mesentery, lung, and heart mast cells of the rat, but only to a minor extent from the corresponding guinea-pig cells. Thapsigargicin induced histamine release from mesentery, lung, and heart mast cells of the rat at concentrations from 0.1 microM but provoked only a release from the corresponding guinea-pig cells in the concentration-range 0.16 to 1.6 microM. Thapsigargin increased the cytoplasmic free calcium level in intact human blood platelets at concentrations from 3.0 nM.
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PMID:The ability of thapsigargin and thapsigargicin to activate cells involved in the inflammatory response. 241 28


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