Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The properties of platelet-activating factor (PAF-acether) 42-48ulus of exocytosis in human neutrophils have been re-investigated with particular attention to effects on cells that were not pretreated with cytochalasin B. Release of gelatinase, the most sensitive marker of exocytosis, was determined in addition to that of vitamin B-12-binding protein and beta-glucuronidase. Superoxide production was assayed as a measure of the respiratory burst. The effects of PAF-acether were compared to those of leukotriene B4 and N-formylmethionylleucylphenylalanine (fMet-Leu-Phe). Our results show that PAF-acether elicits marked secretion in untreated human neutrophils, and refute the prevalent view that cytochalasin B treatment is required for responsiveness. PAF-acether induced abundant release of gelatinase, increasing on average from 20% at 10 nM to 35% at 1 microM. This release was very rapid, i.e., almost complete after 2 min. fMet-Leu-Phe induced the same maximum response already at 0.1 microM, but release was considerably slower. Leukotriene B4 was less potent with a maximum release of 20%. Exocytosis of gelatinase was always paralleled by liberation of smaller but significant amounts of vitamin B12-binding protein from the specific granules. In contrast to their effect on exocytosis, PAF-acether and leukotriene B4 were very weak stimuli of the respiratory burst when compared with fMet-Leu-Phe.
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PMID:Platelet-activating factor as a stimulus of exocytosis in human neutrophils. 301 43

Arachidonate (1-300 microM) mobilized Ca2+ ions from an intracellular store and stimulated the entry of Ca2+ ions from the extracellular fluid in undifferentiated HL-60 cells that had been loaded with Fura-2. The integrated response was biphasic in form: arachidonate liberated Ca2+ ions from the intracellular store first, resulting in a transient increase in cytosolic free Ca2+ concentration ([Ca2+]i). Ca2+ entry from the extracellular fluid was not evident for a further 1-2 min. At baseline, [Ca2+]i was 48.1 +/- 14.0 nM (SEM, n = 5). Upon addition of arachidonate (100 microM), [Ca2+]i rose to a transient peak level of 217 +/- 38.6 nM (SEM, n = 5) and a later plateau level of 427 +/- 118 nM (SEM, n = 5). Removal of added Ca2+ ions from the extracellular fluid in the presence of EGTA (1.0 mM) had no effect on the initial transient response but abolished the second phase of the response. In HL-60 cells that had been loaded with BAPTA/AM, the initial transient phase of the response was abolished but the elevation in [Ca2+]i due to Ca2+ entry from the extracellular fluid was unaffected. Undifferentiated HL-60 cells also responded to arachidonate (100 microM) with an increase in the release of the lysosomal enzyme beta-glucuronidase. Arachidonate-induced beta-glucuronidase release from BAPTA-loaded cells or in control cells exposed to Ca(2+)-free solutions was inhibited by about 50%. In BAPTA-loaded cells that were incubated with Ca(2+)-free solutions, arachidonate-induced beta-glucuronidase release was inhibited by about 90%. Leukotriene B4 failed to elevate [Ca2+]i in the concentration range 0.01-1 microM and failed to activate beta-glucuronidase release in concentrations up to 10 microM. Furthermore, the cyclo-oxygenase/lipoxygenase inhibitor ETYA (100 microM) was without effect on secretion. Consistent with this finding, we found that a large number of unsaturated fatty acids could reproduce the effect of arachidonate on [Ca2+]i and beta-glucuronidase release. Fatty acids belonging to the omega-3, omega-6 and omega-7 unsaturated fatty acid families were effective in elevating [Ca2+]i and stimulating beta-glucuronidase release. However, three unsaturated fatty acids, all belonging to the omega-9 fatty acid family, were ineffective.
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PMID:Arachidonate and other fatty acids mobilize Ca2+ ions and stimulate beta-glucuronidase release in a Ca(2+)-dependent fashion from undifferentiated HL-60 cells. 852 54

Leukotriene B4 (LTB4) is a potent chemoattractant for neutrophils and is thought to play a role in a variety of inflammatory responses in humans. The metabolism of LTB4 in vitro is complex with several competing pathways of biotransformation, but metabolism in vivo, especially for normal human subjects, is poorly understood. As part of a Phase I Clinical Trial of human tolerance to LTB4, four human subjects were injected with 150 nmol/kg LTB4 with one additional subject as placebo control. The urine of the subjects was collected in two separate pools (0-6 and 7-24 h), and aliquots from these urine collections were analyzed using high performance liquid chromatography, UV spectroscopy, and negative ion electrospray ionization tandem mass spectrometry for metabolites of LTB4. In the current investigation, 11 different metabolites of LTB4 were identified in the urine from those subjects injected with LTB4, and none were present in the urine from the placebo-injected subject. The unconjugated LTB4 metabolites found in urine were structurally characterized as 18-carboxy-LTB4, 10,11-dihydro-18-carboxy-LTB4, 20-carboxy-LTB4, and 10,11-dihydro-20-carboxy-LTB4. Several glucuronide-conjugated metabolites of LTB4 were characterized including 17-, 18-, 19-, and 20-hydroxy-LTB4, 10-hydroxy-4,6,12-octadecatrienoic acid, LTB4, and 10,11-dihydro-LTB4. The amount of LTB4 glucuronide (16.7-29.4 pmol/ml) and 20-carboxy-LTB4 (18.9-30.6 pmol/ml) present in the urine of subjects injected with LTB4 was determined using an isotope dilution mass spectrometric assay before and after treatment of the urine samples with beta-glucuronidase. The urinary metabolites of LTB4 identified in this investigation were excreted in low amounts, yet it is possible that one or more of these metabolites could be used to assess LTB4 biosynthesis following activation of the 5-lipoxygenase pathway in vivo.
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PMID:Urinary metabolites of leukotriene B4 in the human subject. 1270 26