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PubMed1987

Levamisole and inorganic pyrophosphate inhibit beta-glycerophosphate induced mineralization of bone formed in vitro.

The addition of the organic phosphate, beta-glycerophosphate, to the culture media of osteoid forming cells or tissues will induce formation of mineralized bone. The mechanisms behind this phenomenon are not clearly understood. In order to gain new understanding of organic phosphate induced mineralization of bone it was decided to attempt to inhibit this process in two fundamentally different ways. Firstly, the reversible inhibitor of alkaline phosphatase, Levamisole, was used to help define the role of alkaline phosphatase in mineralization in vitro. Secondly, inorganic pyrophosphate, a known inhibitor of hydroxyapatite (HA) formation was also used. It was hypothesized that inorganic pyrophosphate, in addition to its ability to block HA formation, might also interfere with organic phosphate access to alkaline phosphatase and thereby prevent mineralization. The data show that mineralization is blocked when alkaline phosphatase activity is inhibited by Levamisole prior to but not after osteoid maturation. Inorganic pyrophosphate blocks organic phosphate induced mineralization whether added before or after osteoid formation. Organic phosphate effects on alkaline phosphatase activity are reversed by the addition of inorganic pyrophosphate either before or after osteoid formation. These findings suggest a role for alkaline phosphatase in organic phosphate induced mineralization. The data show further that inorganic pyrophosphate may effect mineralization of bone not only by blocking apatite formation but possibly by modulating organic phosphate metabolism.

Animals↗
PubMed1986

The exchange of Fe3+ between pyrophosphate and transferrin. Probing the nature of an intermediate complex with stopped flow kinetics, rapid multimixing, and electron paramagnetic resonance spectroscopy.

A detailed study of the exchange of Fe3+ between pyrophosphate and human serum transferrin was undertaken to test the hypothesis of a generalized reaction route for exchange of Fe3+ between transferrin and chelators. The initial rate of Fe3+ transfer from pyrophosphate to apotransferrin-CO2-3 is highly sensitive to the pyrophosphate to iron ratio with a maximal rate being observed at a ratio of 3:1, consistent with the presence of slowly reactive polymeric species at ratios less than 3:1 as revealed by EPR and kinetic measurements. At a ratio of 4:1 the reaction is distinctly biphasic. The rapid first phase results in the formation of an intermediate postulated as a mixedligand complex of the type PPi-Fe3+-transferrin-CO2-3. The intermediate has a distinct EPR spectrum and an absorption spectrum similar to that of Fe3+-transferrin-CO2-3, but with a spectral maximum at 450 nm rather than 465 nm. The second phase principally arises from the slow reaction of polymeric iron-pyrophosphate with the apoprotein and has contributions from the breakdown of the intermediate formed in the first phase. The rate of formation of the intermediate shows a hyperbolic dependence on NaHCO3 and apotransferrin concentrations, the latter suggesting a rate-limiting labilization of Fe3+(PPi)3, perhaps to form species of the type Fe3+(PPi)2, prior to attack by apotransferrin-CO2-3. Multimixing stopped flow spectrophotometry was employed to test the chemical reactivity of the Fe3+ to reduction at various times during the first phase. Surprisingly, a diminution of reactivity of 1000-fold was noted after only 2% of the first phase was completed, indicating a fast initial reaction which is not observed by normal rapid flow spectrophotometry. This initial reaction may involve the binding of iron-pyrophosphate to allosteric sites on the protein. The kinetics of iron removal from Fe3+-transferrin-CO2-3 by PPi are consistent with a rate-limiting conformational change in the protein as proposed earlier.

Apoproteins↗
PubMed1984

Brain dolichyl pyrophosphate phosphatase. Solubilization, characterization, and differentiation from dolichyl monophosphate phosphatase activity.

Dolichyl [beta-32P]pyrophosphate ([beta-32P]Dol-P-P) has been prepared chemically to study Dol-P-P phosphatase in calf brain. Calf brain microsomes catalyze the enzymatic release of 32Pi from exogenous [beta-32P]Dol-P-P by a bacitracin-sensitive reaction. [32P]Pyrophosphate was not detected with the water-soluble product even when 1 mM sodium pyrophosphate was added to impede pyrophosphatase activity. A substantial fraction of the Dol-P-P phosphatase activity can be solubilized by treating brain microsomes with 3% Triton X-100. The detergent extracts catalyze the enzymatic release of 32Pi from [beta-32P]Dol-P-P and the conversion of [14C]undecaprenyl pyrophosphate to [14C]undecaprenyl monophosphate. The solubilized Dol-P-P phosphatase activity: 1) is optimal at neutral pH; 2) is inhibited by Mn2+ and stimulated by EDTA; 3) exhibits an apparent Km = 20 microM for Dol-P-P; 4) is competitively inhibited by undecaprenyl pyrophosphate, and 5) is blocked by bacitracin. Solubilized Dol-P-P phosphatase activity differs from Dol-P phosphatase activity present in the same detergent extracts with respect to: 1) thermolability at 50 degrees C, 2) effect of 20 mM EDTA, and 3) sensitivity to phosphate and fluoride ions. These studies describe the chemical synthesis of [beta-32P]Dol-P-P for use in a convenient assay of Dol-P-P phosphatase activity. A procedure for the solubilization of Dol-P-P phosphatase activity from microsomes is presented, and an enzymological comparison indicates that Dol-P-P and Dol-P phosphatase are separate enzymes in calf brain.

Animals↗
PubMedDate not supplied

[Pyrophosphate analogs in the pyrophosphorolysis reaction catalyzed by Escherichia coli RNA polymerase].

Processive pyrophosphorolysis of RNA from ternary RNA polymerase-nascent RNA-delta D111 T7 DNA complex has been followed in the absence of nucleoside triphosphates. Series of inorganic pyrophosphate analogs were investigated for their ability to sustain the reaction and to compete with inorganic pyrophosphate for the reaction. Methylenediphosphonic, imidodiphosphonic, phosphonacetic acids, inorganic triphosphate, methylenediphosphonic and phosphate were found to be capable of substituting the inorganic pyrophosphate in RNA degradation reaction with tantamount efficiency. They give rise to nucleoside monophosphates for phosphonoacetic acid, nucleoside triphosphates for inorganic pyrophosphate and inorganic triphosphate, nucleoside triphosphates analogs for methylenediphosphonic, imidodiphosphonic acids and methylenediphosphonic acid phosphate as the low molecular weight product of the reaction. The problem of specific interaction of RNA polymerase with nucleoside triphosphates and inorganic pyrophosphate is discussed in the terms of structural requirements for the compounds to be a potent substrate for RNA polymerase.

Binding Sites↗
PubMed1977

Dissociation of prelycopersene pyrophosphate synthetase from phytoene synthetase complex of tomato fruit plastids.

The partially purified phytoene synthetase enzyme complex obtained from tomato fruit plastids dissociates into two or more subunit species on chromatography in low ionic strength buffer on DEAE-cellulose. One of these subunits prelycopersene pyrophosphate synthetase, has a molecular weight of approximately 40,000, whereas the phytoene synthetase complex has a molecular weight of 200,000. The prelycopersene pyrophosphate synthetase catalyzes the conversion of isopentenyl pyrophosphate to geranylgeranyl and prelycopersene pyrophosphates. The identities of these substances were established by thin layer chromatography in several solvent systems. The formation of both geranylgeranyl and prelycopersene pyrophosphates by this enzyme supports earlier results with cruder enzyme systems which suggested that these compounds are intermediates in the synthesis of phytoene.

Carotenoids↗
PubMed1996

Quanticalc assessment of the clinical scaling benefits provided by pyrophosphate dentifrices with and without triclosan.

The Quanticalc (QC) dental scaler permits a quantitative assessment of the work used by professionals in calculus removal through the measurement of force dynamics and scaling strokes applied in calculus debridement. The purpose of this study was to use the QC to compare the clinical effects of two 5% pyrophosphate dentifrices on dental calculus in subjects following six-months' product use. Three-hundred forty-six subjects participated in a six-month, double-blind tartar control clinical trial involving traditional Volpe-Manhold Index (VMI) evaluations. Following the six-month VMI examinations, the subjects had a QC prophylaxis (scaling force measurements). The three dentifrice treatment groups included a control dentifrice (NaF only, Crest); NaF dentifrice containing 5.0% pyrophosphate (Crest Tartar Control); and NaF dentifrice containing 5.0% pyrophosphate plus 0.28% triclosan (antimicrobial). Subjects were balanced by baseline (pretest) VMI scores at the start of the trial. QC examinations revealed statistically significant reductions in total force and stroke number used by the therapist to scale the six anterior VMI teeth for subjects using the pyrophosphate tartar control dentifrices as compared to control dentifrice. The reduction in scaling effort amounted to almost 3 kg per scaling for subjects. QC results paralleled VMI reductions of calculus on the teeth and demonstrated that the use of 5% pyrophosphate dentifrices, with or without triclosan antimicrobial, results in significant reductions in the total (developed) force and strokes required by therapists in regular calculus debridement at a six-month interval. The clinical benefits of tartar control toothpastes may not only include reductions in cosmetically objectionable supragingival calculus, but in reducing professional effort in calculus debridement during regular prophylaxis.

Analysis of Variance↗
PubMed1981

Comparison of phosphohydrolase activities from articular cartilage in calcium pyrophosphate deposition disease and primary osteoarthritis.

One abnormality in calcium pyrophosphate deposition disease (CPDD) which fosters consistently high synovial fluid pyrophosphate ion (PPi) and large accumulations of calcium pyrophosphate dihydrate crystals (Ca pyrophosphate) might be an aberration in chondrocytes involving elaboration of PPi and failure of its hydrolysis within cartilage matrix. Exploration of this hypothesis required further information on the phosphohydrolases in relevant human articular cartilages. Triton X-100 extracts of whole homogenized cartilage from 18 patients with primary osteoarthritis (OA), 10 patients with CPDD and secondary OA, as well as 6 "normal" subjects were partially purified by DE-52 chromatography and eluates studied for phosphohydrolase activity in a variety of substrates, inhibitors, and environmental conditions. Almost all the protein as well as crude alkaline phosphatase and pyrophosphatase activities were clustered in peaks designated I and II. Findings in CPDD cartilage not observed in OA controls were: 1) consistent alkaline phosphatase activity in the void volume of DE-52 columns, 2) high levels of 5'nucleotidase activity, 3) abundant generation of PPi by CPDD cartilage during in vitro incubation of cartilage extract fractions with ATP. This enzymatic behavior is likely to bear a regulatory relationship to PPi production by chondrocytes in CPDD.

Adenosine Triphosphate↗
PubMed1984

Calcium pyrophosphate crystal deposition. An in vitro study using a gelatin matrix model.

Deposition of crystalline triclinic (t) and monoclinic (m) calcium pyrophosphate dihydrate (CPPD) in fibrocartilage and articular cartilage is the hallmark of chondrocalcinosis. Using biologic grade gelatin to model this crystal growth process, t-CPPD, m-CPPD, amorphous calcium pyrophosphate, orthorhombic calcium pyrophosphate tetrahydrate (o-CPPT), and 3 mixed calcium/sodium pyrophosphate salts were grown at physiologic pH. Amorphous and o-CPPT appeared to be kinetic precursor crystals in the formation of t-CPPD and m-CPPD. Optimal concentration ranges for the different crystals were determined.

Calcium↗
PubMed1986

Thallium-201/technetium-99m pyrophosphate overlap in patients with acute myocardial infarction after thrombolysis: prediction of depressed wall motion despite thallium uptake.

Intracoronary thallium-201/technetium-99m pyrophosphate planar scintigraphy was performed in 60 patients with acute myocardial infarction undergoing intracoronary thrombolysis to predict salvage of myocardium immediately after thrombolysis. In eight patients a significant overlap of new thallium uptake and technetium pyrophosphate accumulation was found after thrombolysis. Intravenous planar thallium scintigraphy revealed thallium uptake in the region of overlap in all patients; circumferential profile analysis showed no difference in the thallium scintigrams before and after technetium injections. Both findings indicate that overlap is not the result of scattering of technetium into the thallium window. Emission computed tomography revealed thallium/technetium pyrophosphate uptake in identical slices and regions. Regional wall motion in the area of overlap remained depressed in all patients, in contrast to patients with similar thallium uptake without overlap. These data suggest that thallium/technetium pyrophosphate overlap reflects the close proximity of viable and necrotic myocardial cells and predicts depressed wall motion after thrombolysis.

Adult↗
PubMed1987

Early estimation of acute myocardial infarct size soon after coronary reperfusion using emission computed tomography with technetium-99m pyrophosphate.

Early appearance of positive findings on a technetium-99m pyrophosphate scan has been shown to be associated with the presence of a reperfused acute myocardial infarction (AMI). Early technetium-99m pyrophosphate imaging was performed by emission computed tomography to evaluate reperfusion and to test the feasibility of estimating infarct size soon after coronary reperfusion based on acute positive tomographic findings. Twenty-seven patients with transmural AMI who were treated with intracoronary urokinase infusion followed by percutaneous transluminal coronary angioplasty underwent pyrophosphate imaging 8.7 +/- 2.1 hours after the onset of AMI. None of the 8 patients in whom reperfusion was unsuccessful had acute positive findings. Of 19 patients in whom reperfusion was successful, 17 had acute positive findings (p less than 0.001). In these 17, tomographic infarct volumes were determined from reconstructed transaxial images. The threshold for areas of increased pyrophosphate uptake within the infarct was set at 60% of peak activity by the computerized edge-detection algorithm. The total number of pixels in all transaxial sections showing increased tracer uptake were added and multiplied by a size factor and 1.05 g/cm3 muscle to determine infarct volume. The correlations of tomographic infarct volumes with peak serum creatine kinase (CK) levels (r = 0.82) and with cumulative release of CK-MB isoenzyme (r = 0.89) were good. Moreover, the time to positive imaging was significantly shorter than that to peak CK level (8.5 +/- 2.3 vs 10.4 +/- 2.2 hours, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1980

Phosphonate analogues of pyruvate. Probes of substrate binding to pyruvate oxidase and other thiamin pyrophosphate-dependent decarboxylases.

A number of enzymes catalyze the removal of carbon dioxide from pyruvate through covalent participation of the coenzyme thiamin pyrophosphate. The conversions of the decarboxylated adduct, hydroxyethyl thiamin pyrophosphate, to subsequent products distinguishes the function of these enzymes. Acetaldehyde is produced by pyruvate decarboxylase, acetic acid by pyruvate oxidase and acetyl coenzyme A by pyruvate dehydrogenase. Differences and details of steps prior to decomposition of hydroxyethyl thiamin pyrophosphate can be evaluated through the use of two substrate analogues, methyl acetylphosphonate and acetylphosphonate. Methyl acetylphosphonate and acetylphosphonate are competitive inhibitors toward pyruvate with Escherichia coli pyruvate oxidase and E. coli pyruvate dehydrogenase but the value of the Ki for the oxidase is more than three orders of magnitude higher than for the dehydrogenase. Yeast pyruvate decarboxylase is not inhibited at all under the same conditions. The binding of methyl acetylphosphonate results in ligand-induced changes in the near ultraviolet circular dichorism spectrum of the oxidase. This spectral perturbation is only seen in the presence of the cofactor, thiamin pyrophosphate, strongly suggesting that the inhibitor is binding at the same site as the substrate, pyruvate, on the enzyme. Kinetic data suggest that lipid activators of pyruvate oxidase increase the affinity of the enzyme for pyruvate and its analogues.

Acetaldehyde↗
PubMed1985

Calcium pyrophosphate and pseudogout.

Calcium pyrophosphate deposition disease (CPDD) is a condition in which calcium pyrophosphate dihydrate crystals are deposited in joint articular cartilage, menisci, and synovium. The main clinical presentations of CPDD are chondrocalcinosis--calcification of cartilage, pseudogout--acute joint inflammation due to crystal-induced synovitis, and pyrophosphate arthropathy--degenerative joint disease similar to osteoarthritis associated with calcium pyrophosphate crystal deposition. The clinical importance of CPDD for the arthroscopist is the ability to recognize the condition so that appropriate treatment can be instituted. Arthroscopy is valuable for diagnosis as well as lavage and intraarticular debridement or meniscectomy. Tissue removed for microscopic examination should be sent to the laboratory in saline, since formalin dissolves the crystals. Postarthroscopy treatment of CPDD should include oral antiinflammatory medication. Asymptomatic chondrocalcinosis does not require treatment.

Aged↗
PubMed1987

Synthesis and properties of 2-acetylthiamin pyrophosphate: an enzymatic reaction intermediate.

The synthesis of 2-acetylthiamin pyrophosphate (acetyl-TPP) is described. The synthesis of this compound is accomplished at 23 degrees C by the oxidation of 2-(1-hydroxyethyl)thiamin pyrophosphate using aqueous chromic acid as the oxidizing agent under conditions where Cr(III) coordination to the pyrophosphoryl moiety and hydrolysis of both the pyrophosphate and acetyl moieties were prevented. Although the chemical properties exhibited by acetyl-TPP are similar to those of the 2-acetyl-3,4-dimethylthiazolium ion examined by Lienhard [Lienhard, G.E. (1966) J. Am. Chem. Soc. 88, 5642-5649], significant differences exist because of the pyrimidine ring in acetyl-TPP. Characterization of acetyl-TPP by ultraviolet spectroscopy, 1H NMR, 13C NMR, and 31P NMR provided evidence that the compound in aqueous solution exists as an equilibrium mixture of keto, hydrate, and intramolecular carbinolamine forms. The equilibria for the hydration and carbinolamine formation reactions at pD 1.3 as determined by 1H NMR are strongly dependent on the temperature, showing an increase in the hydrate and carbinolamine forms at the expense of the keto form with decreasing temperature. The concentration of keto form also decreases with increasing pH. Acetyl-TPP is stable in aqueous acid but rapidly deacetylates at higher pH to form acetate and thiamin pyrophosphate. Trapping of the acetyl moiety in aqueous solution occurs efficiently with 1.0 M hydroxylamine at pH 5.5-6.5 to form acetohydroxamic acid and to a much smaller extent with 1.0 M 2-mercaptoethanol at pH 4.0 and 5.0 to form thio ester. Transfer of the acetyl group to 0.5 M dihydrolipoic acid at pH 5.0 and 1.0 M phosphate dianion at pH 7.0 is not observed to any significant extent in water. The kinetic and thermodynamic reactivity of acetyl-TPP with water and other nucleophiles is compatible with a hypothetical role for acyl-TPPs as enzymatic acyl-transfer intermediates.

Acetate Kinase↗
PubMed1990

The route of non-enzymic and enzymic breakdown of 5-phosphoribosyl 1-pyrophosphate to ribose 1-phosphate.

Spontaneous decomposition of 5-phosphoribosyl 1-pyrophosphate at pH 5.5 was established to occur as follows: 5-Phosphoribosyl 1-pyrophosphate----5-phosphoribosyl 1,2-(cyclic)phosphate----ribose 1-phosphate----ribose Enzymic degradation of 5-phosphoribosyl 1-pyrophosphate by alkaline phosphatase from calf intestine and by acid phosphatases from potato and Aspergillus niger was found to proceed according to this pathway within the pH range 2.5-7.4 with accumulation of ribose 1-phosphate. In the case of alkaline phosphatase, Mg2+ ions inhibit the pyrophosphorolysis of 5-phosphoribosyl 1-pyrophosphate and stimulate the hydrolysis of ribose 1-phosphate.

Acid Phosphatase↗
PubMed1991

Deposition of calcium pyrophosphate dihydrate crystals in the ligamentum flavum: evaluation with MR imaging and CT.

Four patients had spinal canal stenosis associated with deposition of calcium pyrophosphate dihydrate within the ligamentum flavum. Radiologic evaluation was performed with magnetic resonance imaging or computed tomography, and surgery was performed on all four patients. Pathologic examination of the surgical specimens demonstrated deposits of calcium pyrophosphate crystals within the ligamentum flavum. Focal enlargement of the ligamentum flavum was present in the cervical spine (n = 1), while a more diffuse, bilateral enlargement was identified in the lumbar spine (n = 3). Enlargement of the ligament either caused or was a component of spinal stenosis that caused neurologic signs or symptoms. Three of the patients had evidence of calcium pyrophosphate deposition elsewhere. Deposition of calcium pyrophosphate dihydrate within the ligamentum flavum causing either focal or diffuse enlargement can be associated with significant spinal stenosis.

Aged↗
PubMed1994

Calcium pyrophosphate arthropathy of the spine: case report and review of the literature.

Calcium pyrophosphate deposition disease is a relatively uncommon arthropathy characterized by the clinical features of pseudogout, the radiographic manifestations of chondrocalcinosis, and the pathological deposition of calcium pyrophosphate crystals in both hyaline and fibrocartilage. Symptomatic involvement of the spine by calcium pyrophosphate deposition disease is rare except by nodular deposition in the ligamentum flavum and atlanto-occipital ligament. We report a 50-year-old woman who presented with an acute herniated disc syndrome secondary to an intraspinal inflammatory calcium pyrophosphate deposition disease mass at the level of the L4-L5 interspace. The magnetic resonance image and histopathological features of the case are also discussed.

Calcium Pyrophosphate↗
PubMed1993

Implications of delayed image on simultaneous thallium-201/technetium-99m pyrophosphate dual emission computed tomography early after acute myocardial infarction.

This study aimed investigate whether thallium-201 and technetium-99m pyrophosphate dual rest-redistribution emission computed tomography early after intracoronary thrombolysis may provide supplementary information for the management of patients with acute myocardial infarction. Fifty patients who received intracoronary thrombolysis underwent simultaneous dual emission computed tomography 3 days after first acute myocardial infarction. All patients who had a technetium-99m pyrophosphate accumulation were selected. Thallium-201/technetium-99m pyrophosphate overlap in the initial and delayed images early after intracoronary thrombolysis identified successful recanalization with sensitivities of 68% and 90% (p < 0.05), specificities of 47% 79% (p < 0.05), positive predictive accuracies of 68% and 88%, negative predictive accuracies of 47% and 80% (p < 0.05), and overall accuracy of 60% and 86% (p < 0.01), respectively. The patients were divided into 3 groups according to the change in thallium-201 uptake from the initial image to the delayed image on dual emission computed tomography: 20 patients had no change in thallium-201 uptake (fixed type), 16 had increases in thallium-201 uptake (redistribution type), and 14 had decreases in thallium-201 uptake (reverse redistribution type). The number of patients with successful recanalization was significantly higher in the redistribution type than in the other types (redistribution type vs reverse redistribution type or fixed type; p < 0.01, respectively). In the redistribution type a frequency of reinfarction in the same infarcted area during the hospital course was significantly higher than in the other types (redistribution type vs reverse redistribution type or fixed type; p < 0.05, respectively), which was mainly due to the patients having high grade residual stenosis. Thus, a thallium-201/technetium-99m pyrophosphate overlap in the delayed image early after acute myocardial infarction can be used as an index for predicting successful early recanalization and probably viable myocardium. In addition, the redistribution patterns on thallium-201 emission computed tomography early after intracoronary thrombolysis can be helpful in identifying patients with successful early recanalization and a high risk subset.

Adult↗
PubMed1979

Pyrophosphate arthropathy.

Pyrophosphate arthropathy has a wide spectrum of clinical symptoms and is a common cause of synovitis in the elderly. The acute "pseudogout" attack is the most commonly recognized, but chronic synovitis might be just as prevalent. Familial pyrophosphate arthropathy with a dominant autosomal heredity is a rare form, with an earlier debut and a more severe prognosis. Another rare expression of pyrophosphate arthropathy is severe joint destruction. The cause of pyrophosphate arthropathy is still unknown. Both individual reactivity and crystal properties determine the intensity of the inflammatory response to crystals.

Acute Disease↗