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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute pancreatitis was experimentally produced in dogs to study the effect of the disease on glucose tolerance. The k value (glucose disappearance coefficient measured in percentage decrease of glucose/min) calculated from the high-dose intravenous glucose-tolerance test was used to evaluate the glucose tolerance of each dog. Thirty dogs were allotted to 3 groups of 10 dogs each as follows: group I--nonsurgical control dogs; group II--surgical control dogs; and group III--pancreatitis-affected dogs. To increase their susceptibility to diabetes, 50% partial pancreatectomies and ductal catheterizations were performed on group II and III dogs. Saline solution was infused into the ductal systems of group II dogs, and staphylococcal alphatoxin was infused into the ductal systems of group III dogs to produce pancreatitis. The results indicated that (1) high-dose intravenous glucose-tolerance test was an effective tool for determining decreased glucose tolerance in dogs; (2) glucose tolerance of group III dogs was markedly decreased compared with that of group I and II dogs; (3) staphylococcal alpha-toxin produced signs of moderately severe pancreatitis; and (4) 50% partial pancreatectomy and saline solution infusion produced clinical and clinicopathologic signs of mild pancreatitis. To determine if a simplified k value (calculated using 2 or 3 blood samples) could closely approximate the standard k value (calculated using 6 blood samples), simplified k values were derived from the 5- and 60-minute blood sample values. These values closely approximated the standard k values, indicating the simplified value may be used in the clinical situation. The standard k value, however, is preferred for investigative work.
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PMID:Effect of staphylococcal alpha-toxin pancreatitis on glucose tolerance in the dog. 94 22

The effect of fat feeding on adipocyte insulin binding was examined to expand a study of adaptive changes in plasma membrane functions. Cells from rats fed a high fat (L) diet for five to seven days bound less insulin and showed a decreased response to insulin (glucose oxidation) compared to those from rats fed a high glucose (G) diet. Both high and low affinity sites were influenced; the extent of the binding difference increased as increasing concentrations of insulin were present in the assay medium. Diet did not change hormone degradation on the capacity of phospholipase C to increase binding. Concanavalin A effects on fat cells were also decreased by L diet both in inhibition of insulin binding and its insulin-like effect on glucose oxidation. Spermine, which had no effect on insulin binding, also had a smaller insulin-like effect on glucose oxidation by L cells than by G cells. Serum insulin was significantly lower (30 +/- 3.7 muU/ml) in L than in G (43 +/- 3.1 muU/ml) groups. Dietary fat produces alterations in fat cells that decrease insulin binding as a part of a complex overall adaptation to the diet.
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PMID:Insulin binding and insulin response of adipocytes from rats adapted to fat feeding. 99 70

Plasma or serum [ 0.1-1.0 ml] was digested with phospholipase C and total lipid extracts were prepared and silylated in the presence of tridecanoylglycerol as internal standard. The neutral lipid and free fatty acid profiles were determined by means of an automated GLC system equipped with an unheated on-column inlet, time actuated liquid injector, programmed heating, cooling and equilibration cycles, and an electronic peak area integrator. The separations were accomplished on a 50 cm x 2 mm i.d. steel column packed with 3% OV-1 on100-120 mesh Gas Chrom Q using nitrogen as a carrier gas in the temperature range 175-350 degrees C. The tube number, peak retention time and peak area were recorded on a punched paper tape, which was subsequently read into a computer via a time-share terminal. The composition of the sample was calculated in relation to the internal standard using a modification of a commercially available computer program and the results were expressed as mg or mole % and characteristic molar ratios of lipid classes. In addition to estimates for total cholesterol and triglyceride, the method provides a detailed account of individual or small groups of molecular species of various lipid classes, which is a major advantage over other automated methods of plasma lipid analyses.
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PMID:Determination of plasma lipid profiles by automated gas chromatography and computerized data analysis. 115 32

During complement lysis of antibody-sensitized sheep erythrocytes (EA) there was a larger loss of membrane phospholipids than during lysis elicited by hypotonic buffer. In addition, membranes prepared from complement-lysed EA had a marked reduction in KSCN (2.4 M)-dissociable membrane cholesterol and phospholipids, as compared to membranes from EA lysed hypotonically. Complement lysis caused a mild reduction in the amount of KSCN-dissociable membrane hexose but no change in the amount of dissociable protein. The impairment in dissociation of membrane lipids was related to the action of C8; it did not occur with membranes from EA that were treated with heat-inactivated (56 degrees C for 30 min) human serum, C4-deficient guinea pig serum, C6-deficient rabbit serum, or the first seven human complement components. EA lysed with limited amounts of complement exhibited a partial impairment in KSCN-dissociable lipids. Membranes from erythrocytes lysed with melittin showed a large increase in dissociation by KSCN of lipids, proteins,and hexoses. Membranes from erythocytes lysed with lysolecithin or phospholipase C showed, in addition to a reduction in dissociable lipid, a much larger reduction in dissociable hexose than a membranes from complement-lysed cells. These profiles of reactivity with 2.4 M KSCN inidcate that the membrane pertubations caused caused by complement may be specific. We conclude that complement-lysis is accompanied by a major rearrangement of membrane cholesterol and phospholipid which could be demonstrated in membranes from cells lysed by only one or very few complement lesions. Therefore, it appears that the lesions induce a propragated change in the lipid organization which extends throughout large areas of the membrane. This change might be responsible for the impairment of membrane permeability that follows the action of complement and results in cell destruction.
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PMID:The indiction by complement of a change in KSCN-dissociable red cell membrane lipids. 125 65

Fructose-1,6-diphosphate (FDP) is a physiological product which exhibits pharmacological properties. This study shows that FDP (1-3 mM) inhibits platelet aggregation induced by the agonists thrombin, vasopressin, platelet activating factor, ADP, adrenaline, arachidonate and the stable thromboxane analogue U 44069. Thrombin-promoted ATP secretion and cytosolic Ca2+ rise are also drastically inhibited by FDP, which decreases, although to a lesser extent, the protein kinase C-dependent phosphorylation of the 47 kDa protein. The inhibition on thrombin-induced aggregation is shared, albeit less efficiently, by glucose-1,6-diphosphate and fructose-2,6-diphosphate but not by other phosphorylated monosaccharides (fructose-1:2 cyclic,6-diphosphate, glucose-1- and glucose-6-phosphate, fructose-1- and fructose-6-phosphate, mannose-6-phosphate and 5-phosphoryl ribose-1-pyrophosphate). FDP does not affect platelet activation induced by the protein kinase C activators dioctanoylglycerol or phorbol 12-myristate 13-acetate. No increase of cAMP concentration is observed in FDP-treated platelets. Altogether, these results indicate that FDP inhibits platelet activation at a level preceding phospholipase C. The data are consistent with a general inhibitory action of FDP on signal transmission.
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PMID:Fructose-1,6-diphosphate inhibits platelet activation. 131 5

The addition of ammonium sulfate to starved yeast cells leads to a 3- to 4-fold rapid increase of the second messengers inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), the products of phosphoinositide-specific phospholipase C (PI-PLC). This response is reduced by dissecting the RAS-activating Cdc25 protein, and is completely abolished by the cdc25-1 mutation even at permissive temperature. Starved cdc25-1 mutant cells have a strongly reduced IP3 content, but an at least 10-fold increased DAG level compared to the isogenic wild-type strain. NH4 does not stimulate cAMP synthesis, and glucose does not induce IP3 and DAG. Our data suggest that the Cdc25 protein controls a nitrogen-specific signalling pathway involving the effector PI-PLC, in addition to the glucose-induced activation of adenylyl cyclase (AC).
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PMID:CDC25-dependent induction of inositol 1,4,5-trisphosphate and diacylglycerol in Saccharomyces cerevisiae by nitrogen. 132 32

We investigated the turnover of polyphosphoinositides in bovine retinal microvascular endothelial cells and rat astrocytes cultured in the presence of high ambient concentrations of glucose in order to study the possible involvement of this pathway in the pathogenesis of diabetic retinopathy. a 35-45% decrease in the amount of 32P incorporated into phosphatidylinositol(4)phosphate (PIP) and phosphatidyl-inositol(4,5)biphosphate (PIP2) occurred in rat astrocytes but not bovine retinal endothelial cells grown for 14 +/- 3 days in a medium with an elevated (28 mM) glucose concentration. Incorporation of 32P into phosphatidylinositol, phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine was not altered by these conditions. A 39-45% decrease in 32P incorporated into PIP/PIP2 was also found in rat astrocytes grown in 28 mM glucose which were detergent solubilized and incubated with [32P]ATP. Exposure to elevated concentrations of glucose decreased the amount of PIP/PIP2 cleaved by ionomycin or fluoroaluminate treatment, but did not disturb phospholipase C activity. Thus, the lower level of PIP/PIP2, induced by exposure to elevated concentrations of glucose, appears due to changes in phospholipid substrate levels, or polyphosphoinositide kinase activity, rather than a decrease in ATP levels or phospholipase C activity. These results suggest that high ambient glucose levels alter second-messenger generation by astrocytes. In turn, cellular interactions dependent upon these second messengers and important for maintenance of normal microvessel function in the retina may be disrupted.
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PMID:Effect of elevated ambient glucose upon polyphosphoinositide turnover in bovine retinal endothelial cells and rat astrocytes. 132 21

Decay-accelerating factor (DAF) is a glycosylphosphatidylinositol-anchored membrane protein that protects cells from damage by autologous complement activation. Of the four mAb against DAF prepared in our laboratory, 1C6 completely blocked DAF function, whereas 5B2 partially blocked it. Using these mAb, we investigated whether human monocytes were activated via DAF molecules. When monocytes were incubated with 1C6 alone, glucose was consumed in significant amounts and phagocytosis of latex beads was enhanced, indicating that the monocytes had been activated. However, 1C6 did not enhance the production of monokines, TNF-alpha, and IL-1 alpha and -beta. The F(ab')2 fragment of 1C6 also activated monocytes, whereas 5B2 and the Fab fragment of 1C6 could not. To further examine monocyte activation, these cells were treated with phosphatidylinositol-specific phospholipase C. Increased glucose consumption and enhanced phagocytic activity by 1C6 were considerably reduced in monocytes treated with phosphatidylinositol-specific phospholipase C. In addition, we found that 1C6 stimulated the generation of inositol trisphosphate. These results demonstrate that the signal transmitted via the DAF molecule is capable of stimulating monocytes.
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PMID:Decay-accelerating factor functions as a signal transducing molecule for human monocytes. 138 May 38

Inositol glycans were prepared from reductively radiomethylated human erythrocyte acetylcholinesterase by sequential treatment with Proteinase K, methanolic KOH, and phosphatidylinositol-specific phospholipase C. Four glycans denoted alpha-delta were resolved by anion exchange high performance liquid chromatography (HPLC). Each glycan was subjected to hydrolysis in 4 M trifluoroacetic acid, and their hexose and hexose phosphate compositions were determined by anion exchange HPLC. The predominant glycan alpha showed a relative stoichiometry of 2 mannoses, 1 mannose 6-phosphate, 1 radiomethylated glucosamine, 1 radiomethylated ethanolamine, and 1 inositol. In contrast, the stoichiometry of glycan beta was 1 mannose, 2 mannose 6-phosphates, 1 radiomethylated glucosamine, 2 radiomethylated ethanolamines, and 1 inositol. Glycans alpha and beta were analyzed by electrospray ionization-mass spectrometry, and respective parent ions of m/z 1266 and 1417 were observed. The fragmentation pattern produced by collision-induced dissociation mass spectrometry of these parent ions was consistent with a common linear core glycan sequence prior to radiomethylation of ethanolamine-phosphate-mannose - mannose - mannose - glucosamine - inositol. Glycan alpha contained a single additional radiomethylated phosphoethanolamine branching from the mannose adjacent to glucosamine, whereas glycan beta contained two additional radiomethylated phosphoethanolamines, one branching from each of the mannoses nearest to glucosamine. Trifluoroacetic acid hydrolysis did not cleave within the N,N-dimethylglucosamine-inositol-phosphate moiety in these glycans, and this component was resolved by anion exchange HPLC and structurally confirmed by mass spectrometry. Dephosphorylation of this component by treatment with 50% HF produced N,N-dimethylglucosamine-inositol, and this conjugate was shown to have a characteristic elution time on cation exchange chromatography in an amino acid analyzer. Both of these fragments involving an intact radiomethylated glucosamine-inositol bond are proposed as new diagnostic indicators in the search for minor glycoinositol phospholipids in cells and tissues.
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PMID:Glycan components in the glycoinositol phospholipid anchor of human erythrocyte acetylcholinesterase. Novel fragments produced by trifluoroacetic acid. 138 56

To study surface molecules of Entamoeba histolytica we produced monoclonal antibodies from mice immunized with lysates from the pathogenic amebic strain HM1:IMSS, and screened them for the ability to inhibit E. histolytica adhesion. One monoclonal antibody, CC 8.6, was a potent inhibitor of amebic adhesion to a Chinese hamster ovary cell line, and was capable of inhibiting HM1:IMSS mediated cytotoxicity by 50%. We found that monoclonal antibody CC 8.6 bound to an amebic glycoconjugate. The glycoconjugate is present only in E. histolytica and not in other Entamoeba sp. It migrates as a polydisperse band on SDS-PAGE, and can be metabolically radiolabeled with [14C]glucose, [32P]phosphate, and [3H]palmitate. The glycoconjugate can be purified by hydrophobic interaction chromatography on octyl-Sepharose; enzymatic hydrolysis with phosphatidylinositol-specific phospholipase C alters the hydrophobic properties of the molecule. HPLC analysis of [14C]glucose-labeled glycoconjugate saccharides revealed that approximately 82% of the incorporated label was in glucose and 12% in galactose. Our studies demonstrate that one of the immunogenic surface molecules of E. histolytica is a phosphorylated, lipid-containing, glycoconjugate, and that antibodies to this antigen may have the potential to protect against E. histolytica adhesion and cytotoxicity.
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PMID:Isolation and partial characterization of a surface glycoconjugate of Entamoeba histolytica. 154 7


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