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PubMed1976

Bone scans of the facial bones: normal anatomy.

Some features of facial anatomy have been identified on 99mTc polyphosphate bone scans by a comparison of scans, radiographs, and photographs. 99mTc polyphosphate bone scans are used clinically to show bone injury and increased osteoblastic activity; the primary use is to identify malignancy and other diseases involving bone. A knowledge of normal anatomy is of the utmost importance in the accurate interpretation of bone scans of the face.

Facial Bones↗
PubMed1985

Assay of diadenosine tetraphosphate hydrolytic enzymes by boronate chromatography.

A new procedure was described for assay of diadenosine tetraphosphate (Ap4A) hydrolases based on boronate chromatography. Potential reaction products, AMP, ADP, and ATP, of the hydrolysis of Ap4A were separated from residual substrate by chromatography on a boronate-derivatized cation-exchange resin, Bio-Rex 70. Separation was achieved by changing the concentrations of ethanol and ammonium acetate in the elution buffers. Picomole masses of products were detectable, blank dpm values were less than 0.5% of the total dpm, and auxiliary enzymes were not required. The procedure was specifically described for Ap4A pyrophosphohydrolase from Physarum polycephalum. The assay is generally applicable for dinucleoside polyphosphate hydrolases which hydrolyze other substrates such as Ap3A, Ap5A, Ap6A, and Gp4G. Dinucleotide polyphosphates are readily purified by chromatography on this boronate resin in a volatile buffer. Tes, Tricine, and Tris buffers significantly interfered with the chromatography of ATP.

Acid Anhydride Hydrolases↗
PubMed1987

Enzymatic fluorometric assay for myo-inositol trisphosphate.

The determination of myo-inositol trisphosphate by an enzymatic fluorometric assay is presented. The method involves the acid extraction of water-soluble inositol polyphosphates followed by separation by anion-exchange chromatography. Samples are subsequently neutralized by passage over a Dowex Cl- resin and elution with lithium chloride. Samples are then desalted with ethanol. Following dephosphorylation with alkaline phosphatase, free myo-inositol is measured enzymatically via the NAD-dependent oxidation to scyllo-inosose with myo-inositol dehydrogenase. The efficiency of recovery, assay specificity, and an application to the measurement of inositol polyphosphates in hormone-stimulated tissue are discussed.

Alkaline Phosphatase↗
PubMed1976

The effect of several diphosphonates on acid phosphohydrolases and other lysosomal enzymes.

Diphosphonates are known to inhibit bone resorption in tissue culture and in experimental animals. This effect may be due to their ability to inhibit the dissolution of hydroxyapatite crystals, but other mechanisms may be important. Since lysosomal enzymes have implicated in the process of bone resorption, we have examined the effect of several phosphonates and of a polyphosphate (P20,2) on lysosomal hydrolases derived from rat liver and rat bone. Dichloromethylene diphosphonate strongly inhibited acid beta-glycerophosphatase (EC 3.1.3.2) and acid p-nitrophenyl phosphatase (EC 3.1.3.2) and to a lesser degree (in descending order) acid pyrophosphatase (EC 3.1.3.-), arylsulfatase A (EC 3.1.6.1), deoxyribonuclease II(EC 3.1.4.6) and phosphoprotein phosphatase (EC 3.1.3.16) of rat liver. Inhibition of acid p-nitrophenyl phosphatase and arylsulfatase A was competitive. Ethane-1-hydroxy-1, 1-diphosphonate did not inhibit any of these enzymes, except at high concentrations. Neither dichloromethylene diphosphonate nor ethane-1-hydroxy-1, 1-diphosphonate had any effect on beta-glucuronidase (EC 3.2.1.31), arylesterase (EC 3.1.1.2) and cathepsin D (EC 3.4.23.5). Of several other phosphonates tested only undec-10-ene-1-hydroxy-1, 1-diphosphonic acid inhibited acid p-nitrophenyl phosphatase strongly, the polyphosphate (P20, I) had little effect. Acid p-nitrophenyl phosphatase in rat calvaria extract behaved in the same way as the liver enzyme and was also strongly inhibited by dichloromethylene diphosphonate, but not by ethane-1-hydroxy-1, 1-diphosphonate. It is suggested that the inhibition of bone resorption by dichloromethylene diphosphonate might be due in part to a direct effect of this diphosphonate on lysosomal hydrolases.

Acid Phosphatase↗
PubMed1988

Evidence that neomycin inhibits plasma membrane Ca2+ inflow in isolated hepatocytes.

The effects of neomycin on Ca2+ fluxes and inositol polyphosphates in hepatocytes were investigated since it has been proposed that this antibiotic inhibits inositol 1,4,5-triphosphate formation in fibroblasts [D. H. Carney, D. L. Scott, E. A. Gordon and E. F. LaBelle, Cell 42, 479 (1985)]. In hepatocytes incubated at 1.3 mM extracellular Ca2+ (Ca2+o) neomycin (2 mM) inhibited 45Ca2+ exchange both in the presence or absence of vasopressin. At 1.3 mM Ca2+o, but not at higher concentrations of Ca2+o, the antibiotic (2 mM) inhibited the increase in glycogen phosphorylase a activity observed at late but not at early times after addition of vasopressin. The antibiotic also inhibited the increase in phosphorylase activity caused by the subsequent addition of 1.3 mM Ca2+o to cells previously incubated in the presence of vasopressin and in the absence of added Ca2+o. The concentration of the antibiotic (2 mM) which gave half-maximal inhibition of phosphorylase activation by vasopressin had no effect on the activation of phosphorylase by glucagon or the release of Ca2+ from intracellular stores induced by vasopressin. At a concentration of 10 mM, neomycin caused a 50% inhibition of the formation of [3H]inositol polyphosphates induced by vasopressin. It is concluded that neomycin, at concentrations which inhibit phosphoinositide-specific phospholipase C in other types of cells inhibits the inflow of Ca2+ across the plasma membrane but does not inhibit inositol trisphosphate formation in hepatocytes.

Animals↗
PubMed1987

Role of a protein regulating guanine nucleotide binding in phosphoinositide breakdown and calcium mobilization by bradykinin in neuroblastoma X glioma hybrid NG108-15 cells: effects of pertussis toxin and cholera toxin on receptor-mediated signal transduction.

The addition of bradykinin to NG108-15 cells resulted in an increase in the intracellular Ca2+ concentration [( Ca2+]i) and the formation of inositol monophosphate, inositol bisphosphate, and inositol trisphosphate in these cells. The bradykinin-stimulated formation of inositol polyphosphates in plasma membrane preparations was dependent on the presence of GTP or guanosine-5'-O-thiotriphosphate (GTP gamma S) but not of GDP. GTP gamma S, unlike GTP, increased the basal formation of inositol polyphosphate in NG108-15 membranes. Iontophoretic injection of GTP gamma S into single cells induced increases in [Ca2+]i. These effects of bradykinin and GTP gamma S on [Ca2+]i and the formation of inositol phosphates in the intact cells and membranes were not affected by treatment of the cells with pertussis toxin or cholera toxin. Data on binding of bradykinin to membrane preparations indicated the presence of two classes of binding sites with Kd values of 0.80 +/- 0.26 and 9.63 +/- 0.13 nM. Approximately 74% of the receptors were in the high affinity state. In the presence of guanyl-5'-yl-imidodiphosphate [Gpp(NH)p], the high affinity sites in the membrane preparations were converted to low affinity sites with no change in the total receptor number. These toxin treatments had no effect on binding of bradykinin to its receptors. Thus, these results indicate that a guanine nucleotide regulatory protein, which is not a substrate of pertussis toxin or cholera toxin, is involved in mediating the effects of bradykinin on membrane-bound phosphoinositide-specific phospholipase C to induce the increase of cytosolic calcium.

Animals↗
PubMed1987

The only inositol tetrakisphosphate detectable in avian erythrocytes is the isomer lacking phosphate at position 3: a NMR study.

Avian red blood cells contain a millimolar amount of inositol polyphosphate which plays a role as an allosteric effector of hemoglobin. We confirmed the structure of this substance by NMR techniques as purely myo-inositol 1,3,4,5,6-pentakisphosphate. Based on present knowledge this effector is synthesized from inositol trisphosphate by successive phosphorylation. In a search for biosynthetic and degradative intermediates of inositol pentakisphosphate we found only one inositol tetrakisphosphate isomer. Its structure was unambiguously assigned by proton, 13C- and 31P-NMR to myo-inositol 1,4,5,6-tetrakisphosphate. As in mammalian cells the major inositol tetrakisphosphate isomer is myo-inositol 1,3,4,5-tetrakisphosphate, there seem to be differences between avian red blood cells and mammalian cells in the routes of inositol polyphosphate formation and/or degradation.

Animals↗
PubMed1996

Involvement of pertussis toxin-sensitive GTP-binding proteins in sphingosine 1-phosphate-induced activation of phospholipase C-Ca2+ system in HL60 leukemia cells.

Exogenous sphingosine 1-phosphate (S1P) induced Ca2+ mobilization, in association with an increase in inositol polyphosphate production reflecting activation of phospholipase C in HL60 leukemia cells. The increase in intracellular Ca2+ concentration ([Ca2+]i) induced by S1P was inhibited by an appropriate treatment of the cells with pertussis toxin (PTX), U73122 (a phospholipase C inhibitor) or phorbol 12-myristate 13-acetate (PMA). In parallel with the Ca2+ response, these agents also inhibited inositol polyphosphate production. The S1P-induced Ca2+ response was also attenuated in the dibutyryl cAMP-induced differentiated cells, where GTP-binding protein-induced Ca2+ response suggested to be enhanced. Lysophosphatidic acid (LPA) also increased [Ca2+]i in the cels, but the maximal response was about half of that of S1P, and furthermore PTX and dibutyryl cAMP treatment hardly affected the LPA-induced Ca2+ mobilization. We conclude that exogenous S1P mobilizes Ca2+ through phospholipase C activation. The S1P-induced enzyme activation is at least partly mediated by PTX-sensitive GTP-binding protein-coupled receptors which may be different from LPA receptors.

Calcium↗
PubMed1985

Occurrence of dinucleosidetriphosphatase in the cytosol and particulate fractions from rat liver.

Dinucleosidetriphosphatase (EC 3.6.1.29) is present in both the 37,000 g rat liver supernatant and precipitate (50 mU/g each fraction). These two activities show matching molecular weights, isoelectric points, substrate specificities, Km values, bivalent cation requirements and inhibition by zinc (II). The particulate triphosphatase and a residual dinucleosidetetraphosphatase (EC 3.6.1.17) are solubilized by freeze-thawing or by Triton X-100. Detergent treatment also extracts an unspecific phosphodiesterase I activity (EC 3.1.4.1) which also splits dinucleoside polyphosphates. The above findings suggest the occurrence of cytosolic and particulate degradative pathways for dinucleoside polyphosphates.

Animals↗
PubMed1980

Computed tomography and bone scintigraphy is polyostotic fibrous dysplasia. Report of a case.

A case of polyostotic fibrous dysplasia is presented in which the extent of bony lesions was defined on the results of the CT scan and bone scan with 99m Tc polyphosphate in addition to conventional radiography. These diagnostic procedures appear to be of considerable value in defining the extent of a variety of oral-maxillofacial bony lesions. This report describes the comparative findings from 99m Tc polyphosphate bone imaging and computed tomography (CT) in one patient with polyostotic fibrous dysplasia.

Adult↗
PubMed1988

Effect of inositol hexakisphosphate on the spectroscopic properties of the nitric oxide derivative of ferrous naturally glycated human hemoglobin HbA1c.

The effect of inositol hexakisphosphate (IHP) on the spectroscopic (EPR and absorbance) properties of the nitric oxide derivative of ferrous naturally glycated human hemoglobin HbA1c (HbA1cNO) has been investigated quantitatively. The results obtained show that 1) both in the absence and presence of IHP, the EPR and absorbance spectra of HbA1cNO show the same basic characteristics described for the nitrosyl derivative of ferrous HbA0, the nonglycated major component of human hemoglobin (HbA0NO); and 2) HbA1cNO binds IHP with an apparent dissociation equilibrium constant (upsilon = 1.8 x 10(-2) M), which is at least four orders of magnitude higher than that estimated for the polyphosphate interaction with HbA0NO (less than or equal to 3 x 10(-6) M). These data provide further independent evidence that interaction(s) of polyphosphates at the specific cleft between beta-chains along the dyad-axis is sterically hindered in HbA1c by the presence of the two glucose residues covalently bound to the N-termini of beta-chains, this finding being in agreement with the reduced effect of polyanions on HbA1c spectral and ligand-binding properties.

Electron Spin Resonance Spectroscopy↗
PubMed1990

Receptor-regulated calcium entry.

A wide variety of hormones and neurotransmitters activate cellular responses by mobilizing cellular Ca2+. In general, this Ca2+ mobilization response is comprised of a release of Ca2+ from intracellular stores, as well as increased entry of Ca2+ into the cytoplasm from the extracellular space. The mechanism for release of intracellular Ca2+ results from the Ca2(+)-mobilizing actions of a second messenger, D-myo-inositol 1,4,5-trisphosphate. Inositol polyphosphates appear also to be involved in the activation of Ca2+ entry, but the mechanism by which this is accomplished is less clear. According to the capacitative model for Ca2+ entry, the depletion of the agonist-regulated intracellular Ca2+ pool by the action of D-myo-inositol 1,4,5-trisphosphate is somehow coupled to the activation of Ca2+ entry. The evidence for this model comes from the demonstration, by diverse strategies, that the same Ca2+ entry mechanism normally activated by Ca2(+)-mobilizing agonists can be equally well triggered by depletion of the intracellular Ca2+ pool, even in the absence of receptor activation or elevated cellular levels of inositol polyphosphates.

Animals↗
PubMed1993

A new NMR airlift bioreactor used in 31P-NMR studies of itaconic acid producing Aspergillus terreus.

An airlift bioreactor for in-vivo NMR studies of cells is described. The 10-mm diameter airlift reactor was constructed for studies of mycelial/pellet forming organisms, grown in suspension. With this device 161 MHz 31P-NMR spectra of living Aspergillus terreus cells, producing itaconic acid, have been obtained. Signals were observed for intra- and extracellular orthophosphate, glycerol-3-phosphorylethanolamine (GPE), glycerol-3-phosphorylcholine (GPC), sugar phosphates and polyphosphate. The spectra also showed broad overlapping resonances in the shift range of NAD(H) and NADP(H). Polyphosphate disappeared when the respiratory gas was exchanged for pure N2. The intracellular pH was estimated at 6.2. In spectra of cell extracts approx. 60 peaks were observed in the range of 20 to -22 ppm, and they confirmed the appearance of the metabolites observed in living cells.

Aspergillus↗
PubMed1982

Salvage of the modified nucleoside ribothymidine in cultured hamster embryo cells.

RNA turnover in hamster embryo cells results in the release of ribothymidine, a methylated nucleoside formed only on intact RNA. [methyl-3H]Methionine ribothymidine polyphosphates and deoxyribothymidine polyphosphates are found in approximately equivalent amounts in the acid-soluble pool of hamster embryo cells. This observation is consistent with prior unexplained observations, in intact animals, that the methyl group of S-adenosyl methionine can be used for deoxythymidine synthesis, This is the only modified ribonucleoside known to be salvaged through pathways in normal cells. Several possible pathways for salvage were investigated.

Animals↗
PubMed1993

Interaction of inositol hexakisphosphate with liganded ferrous human hemoglobin. Direct evidence for two functionally operative binding sites.

Inositol hexakisphosphate (InsP6) binding to the oxygenated, carbonylated and nitrosylated derivatives of ferrous human hemoglobin (HbO2, HbCO and HbNO, respectively) has been measured at pH 7.0 (0.1 M Bis-Tris buffer, 0.1 M NaCl) and 20 degrees C. The observations indicate the presence of two InsP6 binding sites per tetramer in all the heme liganded hemoglobin derivatives, with different affinities for the polyphosphate. For each binding site, InsP6 interacts with similar affinity constants to HbO2, HbCO and HbNO. Such a finding indicates that different heme ligands do not alter significantly the stereochemistry of the polyphosphate binding cleft. This behaviour seems to indicate that, even though different heme ligands are likely to affect the tertiary conformation of the subunit in a different fashion, the perturbation does not seem to be transmitted to the quaternary arrangement of the whole macromolecule, and, thus, to the InsP6 binding site.

Binding Sites↗
PubMed1987

Rapid formation of inositol 1,4,5-trisphosphate in rat pancreatic acini stimulated by carbamylcholine.

Cholinergic stimulation of inositol phosphate formation was studied in isolated rat pancreatic acini, prelabelled with myo-[2-3H]inositol. Carbamylcholine increased incorporation of radioactivity into Ins(1,4,5)P3 and InsP4 within 5 s. Increases in [3H]Ins(1,3,4)P3 were delayed with marked stimulation occurring between 10 s and 1 min. Inositol polyphosphate formation was less sensitive to carbamylcholine concentration than was stimulation of amylase release. At a low (0.3 microM) carbamylcholine concentration, no increase in inositol polyphosphate formation was detected, whereas stimulation of amylase release, which was not dependent on extracellular calcium, was observed. Ins(1,4,5)P3 was shown to release actively accumulated 45Ca2+ from isolated rough endoplasmic reticulum membranes to a similar extent as that released from rough endoplasmic reticulum following cholinergic stimulation of pancreatic acini (Richardson, A.E. et al. (1984) Biochem. Soc. Trans. 12, 1066-1067). The data is consistent with Ins(1,4,5)P3 being produced rapidly enough to release sufficient calcium from the rough endoplasmic reticulum to cause an observed increases in cytoplasmic free Ca2+.

Amylases↗
PubMed1990

P2-purinergic receptors activate a guanine nucleotide-dependent phospholipase C in membranes from HL-60 cells.

We have previously determined that human neutrophils and monocytes, as well as neutrophil/monocyte progenitor cells, express a subtype of P2-purinergic receptors (for ATP) which activate the inositol phospholipid signalling system. In the present study, membranes prepared from HL-60 promyelocytic leukemia cells were used to examine the mechanism by which these ATP receptors activate phosphatidylinositol-specific phospholipase C (PI-PLC) under defined in vitro conditions. Micromolar concentrations of the receptor agonists ATP, UTP, and ATP gamma S stimulated the GTP-dependent formation of inositol bisphosphate (IP2) and inositol trisphosphate (IP3) in washed membranes prepared from undifferentiated HL-60 cells prelabeled with [3H]inositol. The stimulatory effects of these nucleotides on PI-PLC appeared to be mediated through a GTP binding protein since minimal inositol polyphosphate accumulation was observed in the absence of guanine nucleotides. The increased inositol polyphosphate formation triggered by these nucleotide receptor agonists did not result from inhibition of GTP breakdown. Neither was it a consequence of increased [3H]polyphosphatidylinositol levels resulting from enhanced activity of membrane-associated PI- or PIP-kinases. Instead, the stimulated phospholipase activity was apparently receptor-mediated. The rank order of potency observed in these in vitro membrane assays (ATP = UTP greater than ATP gamma S much greater than TTP greater than CTP much greater than beta, gamma-CH-ATP) was similar to that observed with intact HL-60 cells. This order of potency appears to distinguish the P2-purinergic receptors expressed by human phagocytic leukocytes from the P2 gamma-purinergic receptors which activate PI-PLC in turkey erythrocyte membranes.

Animals↗
PubMed1996

Effect of combined lysozyme and lipase treatment on the survival of Listeria monocytogenes.

The effectiveness of polyphosphates or lipases to increase the lytic activity of lysozyme was evaluated both on Listeria monocytogenes suspended in buffer and on growing cultures incubated at different temperatures. At 5 degrees C and 37 degrees C polyphosphates combined with lysozyme did not result in the decrease of the number of non-growing L. monocytogenes cells. At the same incubation conditions, the addition of lipase to lysozyme significantly enhanced the bactericidal activity of lysozyme to an extent determined by pH, NaCl concentration and temperature.

Culture Media↗