Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma samples obtained during a prevalence study of hyperlipemia in a free-living urban population were analyzed for phosphatidylcholine, sphingomyelin and lysophosphatidylcholine content by automated high-temperature gas--liquid chromatographic (GLC) and manual colorimetric phosphorus (thin-layer chromatographic, TLC) methods. The GLC estimates were obtained from a quantitative analysis of the diacylglycerol, ceramide and monoacylglycerol moieties released from the parent phospholipids by digestion with phospholipase C, while the TLC estimates were derived by manual colorimetric phosphorus analyses of the individual phospholipid classes resolved by TLC. On samples analyzed over a two-year period the methods gave excellent correlation for the total phospholipids (r = 0.98), phosphatidylcholine (r = 0.98) and sphingomyelin (r = 0.90), but resulted in a poor agreement for lysophosphatidylcholine (r = 0.69). Comparable results were obtained for estimates of these phospholipids in plasma very low density, low density and high density lipoproteins. The between-method coefficient of variation ranged from 3 to 5% for phosphatidylcholine and from 5 to 10% for sphingomyelin. The relative error for the estimates of lysophosphatidylcholine ranged from 10 to 25%, and was due to the inclusion in the GLC estimates of a variable proportion of plasma free monoacylglycerols. Other differences between the two methods are due to various analytical errors and biases inherent in the two techniques. The within-day, within GLC, relative error averaged 1% for phosphatidylcholine, 3% for sphingomyelin and 5% for lysophosphatidylcholine. The apparent high precision and accuracy of the GLC method recommend it as an alternative to conventional direct methods of phospholipid analyses based on TLC isolation of lipid classes and colorimetric measurements of their phosphorus content. The GLC analyses of the plasma phospholipids are particularly convenient in conjunction with GLC measurements of plasma cholesterol and triacylglycerols, where a smaller throughput of samples is not a limitation and where both total amount and relative proportion of the lipids are of interest.
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PMID:Comparative determination of plasma phospholipids by automated gas--liquid chromatographic and manual colorimetric phosphorus methods. 738 Aug 92

Endogenous phospholipid metabolism in stimulated human platelets was studied by phosphorus assay of major and minor components following separation by two-dimensional thin-layer chromatography. This procedure obviated the use of radioactive labels. Extensive changes were found in quantities of phosphatidylinositol (PI) and phosphatidic acid (PA) as a consequence of thrombin or collagen stimulation. Thrombin addition was followed by rapid alterations in the amount of endogenous PI and PA. The decrease in PI was not precisely reciprocated by an increase in PA when thrombin was the stimulus. This apparent discrepancy could be explained by removal of a transient intermediate in PI metabolism, such as diglyceride, formed by PI-specific phospholipase C (Rittenhouse-Simmons, S., J. Clin. Invest.63: 580-587, 1979). Diglyceride would be unavailable for PA formation by diglyceride kinase, if hydrolyzed by diglyceride lipase (Bell, R. L., D. A. Kennerly, N. Stanford, and P. W. Majerus. Proc. Natl. Acad. Sci. U. S. A.76: 3238-3241, 1979) to yield arachidonate for prostaglandin endoperoxide formation. Thrombin-treated platelets also accumulated lysophospho-glycerides. Specifically, lysophosphatidyl ethanolamines accumulated within 15s following thrombin addition. Fatty acid and aldehyde analysis indicated phospholipase A(2) activity, with an apparent preference for diacyl ethanolamine phosphoglycerides. In the case of collagen, these changes occurred concomitantly with aggregation and consumption of oxygen for prostaglandin endoperoxide formation.THESE STUDIES OF ENDOGENOUS PHOSPHOLIPID METABOLISM PROVIDE INFORMATION SUPPORTING THE EXISTENCE OF TWO PREVIOUSLY POSTULATED PATHWAYS FOR LIBERATION OF ARACHIDONIC ACID FROM PLATELET PHOSPHOLIPIDS: (a) the combined action of PI-specific phospholipase C plus diglyceride lipase yielding arachidonate derived from PI; and (b) a phospholipase A(2) acting primarily on diacyl ethanolamine phosphoglyceride.
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PMID:Phospholipid metabolism in stimulated human platelets. Changes in phosphatidylinositol, phosphatidic acid, and lysophospholipids. 740 Mar 15

The iodoplatinate (IP) reaction, a selective method for visualization of phospholipids, was applied to the predentine and dentine of rat incisors and compared with malachite green aldehyde (MG) fixation/staining. Spot tests indicated (1) that IP specifically stains phospholipids, but not amino acids, displaying as do phospholipids, quaternary ammonium groups; and (2) phosphatidylserine and sphingomyelin were also stained by MGA. Although this reagent is known to interact with phosphorus, phosphoproteins remained unstained. In the rat incisor, an IP-positive network including granules and thin filaments was seen in predentine in the inter-collagen spaces, in many cases closely associated with collagen fibres and their periodic striations. In dentine, positively stained needle-like structures were located along individual collagen fibres, or at the surface of groups of collagen fibres. This staining pattern was unchanged on sections of material pretreated with acetone, whereas the staining was abolished or markedly reduced when the samples were treated either with chloroform/methanol or phospholipase C prior to the IP reaction. Pretreatment of the samples with hyaluronidase promoted subsequent diffusion of the staining. A very similar staining pattern was observed with MGA, in accordance with earlier reports. The present findings validate the histochemical results reported previously on the distribution and potential role(s) of phospholipids in dentine biomineralization.
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PMID:Iodoplatinate visualization of phospholipids in rat incisor predentine and dentine, compared with malachite green aldehyde. 751 28

Development of biological and clinical uses of in vivo 31P magnetic resonance spectroscopy has been hampered by poor anatomic localization of spectra and poor resolution of overlapping signals within phosphomonoester and phosphodiester regions of the spectrum. We applied 1H-decoupling and nuclear Overhauser enhancement to improve resolution of 31P magnetic resonance spectra accurately localized to 21 non-Hodgkin's lymphomas (NHL) by using three-dimensional chemical shift imaging. All 21 spectra had large phosphomonoester signals (26% of total phosphorus) that contained high amounts of phosphoethanolamine relative to phosphocholine. There were no signals from glycerophosphoethanolamine or glycerophosphocholine but only a broad signal from membrane phospholipids in the phosphodiester region (20% of phosphorus). Prominent nucleoside triphosphates (47% of phosphorus) and low inorganic phosphate (7% of phosphorus) indicate well-perfused tissue with viable cells. Mean intracellular pH was 7.23. These characteristics were similar in all grades and stages of NHL. By analogy with recently reported studies in cell lines in vitro, we hypothesize that the pattern of phospholipid metabolites observed in NHL in vivo is partly a manifestation of sustained activation of phospholipase C or D. The techniques we implemented permitted us to obtain more information about in vivo metabolism of NHL than has heretofore been available. This information is important for the establishment of appropriate experimental models and provides a basis from which to examine potential clinical uses of 31P magnetic resonance spectroscopy.
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PMID:Metabolic characterization of human non-Hodgkin's lymphomas in vivo with the use of proton-decoupled phosphorus magnetic resonance spectroscopy. 761 63

Activation of phospholipase C has been implicated as a factor in the development of irreversible tissue damage following injury to the central nervous system. We have used phosphorus magnetic resonance spectroscopy and a battery of postinjury motor function tests to characterize the role that phospholipase C activity may play in determining biochemical and neurologic outcome following traumatic brain injury in rats. Moderate (2.7 atmospheres) fluid percussion induced lateral brain injury caused a decline in free magnesium concentration, phosphorylation potential, and increased mitochondrial rate of oxidative phosphorylation. Neurologic motor score at 24 h and 1 week posttrauma in these animals was consistent with moderate injury. In contrast, treatment with the phospholipase C inhibitor neomycin B (15 mg/kg i.v.) immediately prior to injury significantly improved free magnesium status, bioenergetic state and neurological outcome (P < 0.01) after injury. We propose that phospholipase C activated second messenger pathways affecting magnesium homeostasis are involved in determining outcome after brain injury.
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PMID:Inhibition of phospholipase C with neomycin improves metabolic and neurologic outcome following traumatic brain injury. 770 17

Calcium and phosphorus metabolism is mainly regulated by PTH through its actions on kidney and bone. PTHrP, which is associated with the hypercalcemia of malignancy syndrome, binds to and activates the same receptor that PTH does. cDNA clones of PTH/PTHrP receptors from rat osteosarcoma (ROS 17/2.8) and opossum kidney (OK) cells are highly homologous and are members of a novel G protein-linked receptor family that includes calcitonin, glucagon, GLP-1, GHRH, VIP, and secretin receptors. Analysis of the protein sequence predicts a receptor with 7 transmembrane domains, a 155 amino acids (aa) extracellular (EC) N-terminal, and 130aa intracellular C-terminal domaina. The extracellular domain has 6 conserved cysteines and 4 potential glycosylation sites. When transfected in COS cells, both receptors are able to bind PTH and PTHrP active fragments with equal affinity. Likewise, agonists activate both adenylate cyclase and phospholipase C efficiently. The N-terminal EC domain and the first EC loop seem to determine the receptor binding capacity with the agonists. Activation of adenylate cyclase and phospholipase C might involve multiple sites between the 3rd helix and the C-terminal tail. Partial characterization of the rat PTH/PTHrP receptor gene demonstrates the existence of at least 15 exons. The first six transmembrane domains are encoded by separated exons. The PTH/PTHrP receptor mRNA is expressed mainly in kidney and bone, and also is widely expressed in many tissues, but not all. A major 2.3-2.5 kb transcript is observed in all these tissues. Nevertheless, 2 larger transcripts are observed in kidney and liver, and multiple smaller mRNA species are observed in kidney, skin, and testis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Mode of action of parathyroid hormone (PTH) and PTH-related peptide (PTHrP) in target organs]. 785 77

The hypothesis that a large, possibly toxic, increase in cellular calcium accompanies photoreceptor cell degeneration in several different Drosophila mutants was tested. The calcium content of wild type and mutant photoreceptors of Drosophila was measured using rapid freezing of the eyes and energy-dispersive x-ray analysis (e.d.x.) of cryosections and semithin sections of cryosubstituted material. Light- and dark-raised mutants of the following strains were studied: retinal degeneration B (rdgB); retinal degeneration C (rdgC); neither inactivation nor afterpotential C (ninaC), and no receptor potential A (norpA). These are light-dependent retinal degeneration mutants in which the affected gene products had been previously shown as myosin-kinase (ninaC), calcium-dependent phosphoprotein phosphatase (rdgC), phosphoinositide transfer protein (rdgB), and phospholipase C (norpA). In light-raised mutants, ommatidia of variable degrees of degeneration were observed. Mass-dense globular bodies of 200-500 nm diameter in relatively large quantities were found in the degenerating photoreceptor of all the mutants tested. These subcellular globules were found to have a very high calcium content, which was not found in wild type or in nondegenerating photoreceptors of the mutants. Nondegenerating photoreceptors were found not only in dark-raised mutants, but in smaller quantities also in light-raised mutants. Usually these globular structures contained high levels of phosphorus, indicating that at least part of the calcium in the mutant photoreceptors is precipitated as calcium phosphate. The results indicate that a large increase in cellular calcium accompanies light-induced photoreceptor degeneration in degenerating Drosophila mutants even when induced by very different mutations, suggesting that the calcium accumulation is a secondary rather than a primary effect in the degeneration process.
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PMID:Accumulation of calcium in degenerating photoreceptors of several Drosophila mutants. 791 26

Labelling with [3H]glucosamine was used to prepare a transforming growth factor-beta 1 (TGF-beta 1)-sensitive glycosylphosphatidylinositol (GPI) from monolayer cultures of rabbit articular chondrocytes (RAC), which may be involved in control of the cell cycle. The polar headgroup of this glycosylphosphatidylinositol was generated by both phosphatidylinositol-specific phospholipase C (PI-PLC) and pronase E digestion. The molecule emerged in only one peak on a Dowex AG1-X8 chromatogram, eluted at 0.1 N ammonium formate. In contrast, similar experiments performed on cellular extract from cultures previously labelled with [3H]glucosamine displayed four radioactive peaks eluting at 0.1, 0.2, 0.5 and 1 N ammonium formate, respectively. Evidence that the eluting position of these peaks was dependent on the number of phosphate residues present in each fraction was demonstrated by both [32P]phosphorus labelling and change in the position of alkaline phosphatase-induced shift in elution volume. We also demonstrated that the GPI-derived inositolphosphate glycan (IPG) could be hyperphosphorylated into the cell under the action of a kinase whose activity was enhanced by TGF-beta 1 itself. We have also shown that all of these IPG forms could mimic the TGF-beta-induced increase of DNA replication rate of RAC, with a higher activity for peaks III and IV than peaks I and II.
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PMID:Different phosphorylated forms of inositolphosphate glycan could be involved in the transforming growth factor-beta 1 (TGF-beta 1) signalling pathway. 808 80

Phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy was used to study the effects of perfluoro-n-octanoic acid (PFOA), perfluoro-n-decanoic acid (PFDA), and clofibrate (CLOF) on liver phosphorus metabolism in rats and guinea pigs in vivo. All three compounds are known to cause peroxisome proliferation in rats but not in guinea pigs. The data indicate that indices related to overall tissue viability (i.e., adenosine triphosphate levels) remain unaffected at the doses and experimental times investigated for all treatments and both species. PFDA-treated rats revealed a marked increase in a liver phosphomonoester resonance compared with corresponding controls (p < or = 0.01); no such effect was observed in guinea pigs. This particular 31P NMR signal was identified as phosphocholine (PCho) and was found to steadily increase in concentration at consecutive days post-PFDA treatment, reaching 6.26 +/- 0.29 mumol/g liver at 5 days. This is fourfold greater than the PCho levels determined in livers from corresponding pair-fed control rats. The elevation in liver PCho is a specific response of PFDA treatment in rats and is not simply related to peroxisome proliferation in general, since neither PFOA nor CLOF produce such an effect. The data suggest a unique effect of PFDA on liver phospholipid metabolism, specifically phosphatidylcholine, which may involve enhanced phospholipid turnover via phosphatidylcholine-specific phospholipase C activity.
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PMID:Effects of perfluoro-n-octanoic acid, perfluoro-n-decanoic acid, and clofibrate on hepatic phosphorus metabolism in rats and guinea pigs in vivo. 812 61

The action of phospholipase C (PLC) from Bacillus cereus on phosphatidylglycerol (PG), derived from egg yolk phosphatidylcholine (PC), was examined in an ether-water mixture. The PLC cleavage of PG and PC followed a Michaelis-Menten kinetics with apparent Vmax values per 1 microgram enzyme of 0.26 and 0.91 mumol.min-1 and Km values of 10 and 12 mM, respectively. When the same enzymic reaction was carried out in minimally buffered aqueous solution of 1% Triton X-100, the decrease in pH with respect to phospholipid cleavage was as expected with PC but much less pronounced with PG. This could be accounted for by the formation of a cyclic glycerophosphate, rather than alpha-glycerophosphate, in the PLC hydrolysis of PG. Examination of the chemical nature of the water-soluble product of PG by phosphorus nuclear magnetic resonance (31P NMR) revealed a single band at 2.31 ppm, while the bands of alpha-glycerophosphate and beta-glycerophosphate appeared at 5.12 and 4.57 ppm, respectively. Basic hydrolysis of the phospholipase cleavage product of PG (0.1 M NaOH for 1 min at 80 degrees C) followed by neutralization shifted its 31P NMR band to 5.18 ppm, which practically coincided with that of alpha-glycerophosphate. Analogous experiments were carried out with PG labeled with 3H at the carbon 2 of the glycerol headgroup ([3H]PG). Autoradiography of thin layer chromatography (TLC) of the [3H]PG enzymic hydrolyzate displayed a single 3H-labeled compound, which could be converted to alpha-glycerophosphate by basic hydrolysis. These results strongly suggest that the phosphate headgroup of PG is cleaved off by PLC as 1,3-cyclic glycerophosphate. A series of PLC experiments with phosphatidyl dihydroxyacetone and phosphatidyl 1,3-propanediol as model substrates supported this assignment. Two-dimensional homonuclear 1H NMR correlated spectra as well as infrared spectra carried out on the isolated sodium salt of this product could further confirm such a structure. The unique structure and chemical nature of 1,3-cyclic glycerophosphate may bear a distinct physiological function.
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PMID:Formation of 1,3-cyclic glycerophosphate by the action of phospholipase C on phosphatidylglycerol. 831 78


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