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PubMed2000

Diadenosine polyphosphates cause contraction and relaxation in isolated rat resistance arteries.

The effects of diadenosine polyphosphates (APnA; n = 3-6) and adenine nucleotides on contractile reactivity of isolated rat mesenteric resistance arteries (MrA) and superior epigastric arteries (SEA), which display a dense and sparse autonomic innervation, respectively, were evaluated. All agonists examined, except adenosine and AMP, induced contractions. The rank order of potency was similar in both arteries: alpha,beta-methylene ATP (alpha,beta-meATP) > AP5A > AP6A > AP4A > ATP > ADP > AP3A. Contractions were stable during several minutes in SEA but highly transient in MrA. They were reduced after exposure to 10 microM alpha,beta-meATP and by 10 microM of the P2X antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid. During phenylephrine (10 microM)-induced contractions, the agonists induced a further contraction in SEA. In MrA, however, further contraction was followed by marked relaxation. The rank order of relaxing potency was comparable to that of the contractile potency of agonists. Also, the relaxing effects of APnA were blunted by 10 microM pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid and after exposure to alpha,beta-meATP. In vitro and in vivo sympathectomy with 6-hydroxydopamine and removal of the endothelium did not modify the effects of APnA in MrA. Thus, the contractile effects of APnA in resistance arteries 1) are due to a P2X purinoceptor-mediated stimulation of the smooth muscle; 2) depend on the length of the phosphate chain; and 3) are followed by endothelium-independent relaxing effects in MrA but not SEA, which may involve receptors that are similar to those mediating contraction. The regional heterogeneity of APnA effects cannot be attributed to a direct neurogenic influence.

Adenine Nucleotides↗
PubMed2001

Contribution of nitric oxide and prostanoids to the cardiac electrophysiological and coronary vasomotor effects of diadenosine polyphosphates.

We investigated the hypothesis that the coronary vasomotor and cardiac electrophysiological effects of diadenosine polyphosphates (Ap(n)A) are mediated via release of nitric oxide and prostanoids. Transmembrane right ventricular action potentials, refractory periods, and coronary perfusion pressure were recorded from isolated, Langendorff-perfused guinea pig hearts studied under constant flow conditions. The effects of threshold (1 nM) and maximal (1 microM) concentrations of diadenosine triphosphate (Ap3A), tetraphosphate (Ap4A), pentaphosphate (Ap5A), and hexaphosphate (Ap6A) were studied in the presence of nitric oxide (NO) synthase inhibitors [L-NG-nitroarginine methyl ester, 300 microM; or L-N5-(1-iminoethyl)ornithine, 30 microM] or cyclooxygenase inhibitors (indomethacin, 100 microM or meclofenamate, 10 microM). Inhibition of cyclooxygenase and NO synthase both prevented the increases in action potential duration and refractory periods seen in response to Ap(n)A. Cyclooxygenase inhibition altered the vasomotor effects of the Ap(n)A in a manner that was related to the structure of the Ap(n)A compound (the effects of Ap3A were attenuated and those of Ap4A and Ap5A were prevented, while those of Ap6A were not abolished.) Inhibition of NO synthase did not abolish the vasomotor responses. These results demonstrate the importance of nitric oxide and prostanoids in the cardiac responses to Ap(n)A and support the hypotheses that the coronary vasomotor responses to Ap(n)A are mediated via release of prostanoids, that this is related to the structure of the compound, and that the cardiac electrophysiological responses to Ap(n)A involve both nitric oxide and prostanoid release.

Action Potentials↗
PubMed1975

[Technetium polyphosphate and technetium diphosphonate. A comparative study].

99mTc-labelled phosphates are the bone seeking agents of choice. The comparison of 99mTc-polyphosphate (Poly-P) and 99mTc-ethane-1-hydroxy-1,1-diphosphonate (EHDP) shows a better in vitro stability of the latter during the first two hours after preparation. The blood clearance of EHDP is superior to Poly-P resulting in reduced background activity at scanning time. Renal excretion over a 4-hour period of urine sampling showed no significant differences between both substances. Blood activity is independent of diuresis.

Adult↗
PubMed1975

Increased 99mTc-polyphosphate muscle uptake in a patient with polymyositis: case report.

A patient with well-documented rheumatoid arthritis and polymyositis displayed abnormal muscle uptake of 99mTc-polyphosphate during routine bone scanning for occult malignancy. The regions of increased uptake corresponded to the areas of clinically active inflammatory muscle disease. On serial scans the degree of muscle labeling correlated well with both clinical and laboratory indices of disease activity.

Adult↗
PubMed1976

Relative accretion of 99mTc-polyphosphate by forming and resorbing bone systems in rats: its significance in the pathologic basis of bone scanning.

The relative roles of osteogenesis andd osteolysis in the production of positive radionuclide images of skeletal lesions were investigated. The uptake of 99mTc-polyphosphate (Tc-PP) by each process was measured in an animal model that permitted bone formation and resorption to be studied independently. Ten rats received intramuscular implants of bone-forming demineralized matrix (DM) and resorbing devitalized bone (DV). Radiographs and Tc-PP scintiscans were made each week thereafter. At 6-10 weeks, the implants and normal bone samples were removed, counted for 99mTc, and examined histologically. The uptake of Tc-PP BY DM implants was first detected on images made 3 weeks after implanatation, and by DV implants, 1-2 weeks later. Serial radiography showed progressive calcification of DM an resorption of DV implants. Microscopic examinations of undecalcified sections, stained with a modified Goldner preparation, revealed vital-bone formation in the DM implants and osteoclastic resorption in the DV. Activity counts per gram of DM and DV implants were, respectively, 200% and 90% that of normal bone. Since only the bone-forming system (DM) accumulated Tc-PP at greater than normal concentrations, this study indicates that positive bone images of osteolytic lesions solely reflect compensatory osteogenic responses.

Animals↗
PubMed1976

Rat model for acute myocardial infarction: application to technetium-labeled glucoheptonate, tetracycline, and polyphosphate.

Cauterization of rat myocardium serves as a quick (2 min) inexpensive technique to create an animal model of acute myocardial infarction useful in evaluating radiopharmaceuticals as potential clinical imaging agents. Preliminary evidence indicates that is correlates well with behavior in man. Application of the model led to the discovery, confirmed by later investigators, that chelating agents such as glucoheptonate and polyphosphate show significant uptake in recent myocardial lesions.

Animals↗
PubMed2002

[Feasibility of calcium polyphosphate fiber as scaffold materials for tendon tissue engineering in vitro].

OBJECTIVE: To study the feasibility of calcium polyphosphate fiber (CPPF) as the scaffold material of tendon tissue engineering. METHODS: CPPF (15 microns in diameter) were woven to form pigtail of 3 mm x 2 mm transverse area; and the tensile strength, porous ratio and permeability ratio were evaluated in vitro. Tendon cells (5 x 10(4)/ml) derived from phalangeal flexor tendon of SD rats were co-culture with CPPF scaffold or CPPF scaffold resurfaced with collagen type-I within 1 week. The co-cultured specimens were examined under optical and electric scanning microscope. RESULTS: The tensile strength of CPPF scaffolds was (122.80 +/- 17.34) N; permeability ratio was 61.56% +/- 14.57%; and porous ratio was 50.29% +/- 8.16%. CPPF had no obvious adhesive interaction with tendon cells, while CPPF of surface modified with collagen type-I showed good adhesive interaction with tendon cells. CONCLUSION: The above results show that CPPF has some good physical characteristics as scaffold of tendon tissue engineering, but its surface should be modified with organic substance or even bioactive factors.

Animals↗
PubMed2002

[Experiment of histocompatibility and degradation in vivo of artificial material calcium polyphosphate fiber].

OBJECTIVE: To study the histocompatibility and degradation in vivo of a new artificial material, calcium polyphosphate fiber (CPPF), and to provide some experimental basis for further study in tendon tissue engineering. METHODS: CPPF and carbon fiber (CF) as control material were implanted in symmetry part in subcutaneous layer, muscle and Achilles tendon of 20 SD rats. The day of operation, the 4th, 8th, 12th, 16th, and 20th weeks after operation, X-ray examination was performed to detect the density change of materials. Local tissue and materials were observed grossly, and pathological examination was made with HE staining 4, 8, 12, 16 weeks after operation. RESULTS: CPPF degraded completely within 16 weeks in muscle, and in 20 weeks after implantation in Achilles tendon and subcutaneous layer according to X-ray and pathological examination. No calcium phosphate crystal deposit was observed in local tissue. No obviously degradation of CF was found within 20 weeks. Local infiltration of lymphocytes and macrophagocytes around CPPF were much fewer than that of CF. CPPF combined compactly with surrounding hyperplastic tissue. CONCLUSION: CPPF degrade thoroughly from 16 to 20 weeks without sediment of crystal of calcium phosphate in vivo. CPPF has good histocompatibility and can be used as a scaffold material of tissue engineering.

Animals↗
PubMed1992

Structural and functional characterization of an inositol polyphosphate receptor from cerebellum.

An inositol polyphosphate receptor has been purified from bovine cerebellum which consists of three different polypeptides with Mr of 111,000, 102,000, and 52,000. Negative staining electron microscopy reveals globular-like structures 10-13 nm in diameter. The receptor has a Stokes radius of 400,000 daltons as determined by molecular sieve high performance liquid chromatography. The receptor preparation binds inositol 1,3,4,5-tetrakisphosphate, inositol hexaphosphate (or phytol), and inositol 1,4,5-trisphosphate (IP4, IP6, and IP3, respectively) with submicromolar affinity (0.19, 0.15, and 0.54 microM, respectively) at conditions approximating physiological ionic strength and pH. The purified receptor preparation, when reconstituted into planar bilayers, displays ion channel activity, preferentially permeable to K+. Permeability ratios of the channel are PK+/PNa+ approximately 5 and PK+/PCl approximately 19. In symmetrical 100 mM KCl, the channel is characterized by long open times (minutes) with a conductance of 7.2 picosiemens. The channel is selectively modulated by IP4. That is, at 1 microM IP4, the mean open time decreased substantially to rapid flicker behavior and the channel is completely closed at 10 microM IP4. IP6 and IP3 did not modulate the channel under similar conditions. Thus, the channel appears to be an IP4-modulated K+ channel.

Animals↗
PubMed1992

Complex inositol polyphosphate response induced by co-cross-linking of CD4 and Fc gamma receptors in the human monocytoid cell line U937.

The cell-surface Ag CD4, which is characteristic for Th lymphocytes, can also be found with a lower density on monocytes/macrophages. Co-cross-linking of CD4 and Fc gamma R by an anti-CD4 mAb (MAX.16H5) and by excess of goat anti-mouse Ig induced a biphasic increase of the free cytosolic Ca(2+)-concentration ([Ca2+]i) in the human monocytoid cell line U937 as measured by FURA-2 fluorescence. A rapid rise from 100 to 150 nM [Ca2+]i to 750 to 900 nM within 1 min was followed by a decline to about 200 to 300 nM within the next 2 to 3 min. This kinetic is characteristic also for blood monocytes and differs significantly from CD4-mediated Ca(2+)-mobilization in T lymphocytes. The rise in [Ca2+]i in U937 cells was not observed when F(ab)2 fragments of MAX.16H5 and F(ab)2 fragments of the cross-linker were used indicating the involvement of Fc gamma R. Time course analysis using HPLC and a recently developed post-column dye system for mass analysis revealed a complex inositol polyphosphate response with rapid increases not only in inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate, but also in D/L-inositol 1,4,5,6-tetrakisphosphate, inositol 1,3,4,5,6-pentakisphosphate, and inositol hexakisphosphate after co-cross-linking of CD4 and Fc gamma R. In conclusion, co-cross-linking of CD4 and Fc gamma R, which may occur in vivo during HIV infection or treatment with therapeutic anti-CD4 antibodies, appears to be a strong activation mechanism for the inositol polyphosphate/Ca2+ signal transduction pathway in U937 cells.

Antigens, Differentiation↗
PubMed2003

A method for screening polyphosphate-accumulating mutants which remove phosphate efficiently from synthetic wastewater.

The biological process for phosphorus removal from wastewater is based on the use of bacteria capable of accumulating inorganic polyphosphate (polyp). We previously showed that a phoU mutation leads to polyp accumulation in Escherichia coli. The phoU mutant could be easily screened on agar plates containing 5-bromo-4-chloro-3-indolyl-phosphate (X-P(i)) after N-methyl-N'-vitro-N-nitrosoguanidine (NTG) mutagenesis. Here, we demonstrate that this method is also useful for screening polyp-accumulating mutants of bacterial strains isolated from soil and activated sludge samples.

Journal Article↗
PubMed1975

Radioisotopic detection of osseius metastases. Evaluation of 99mTc polyphosphate and 99mTc pyrophosphate.

A total of 146 patients were investigated for the presence of osseous metastases with 99mTc polyphosphate or 99mTc pyrophosphate bone scans. Results of bone imaging were retrospectively compared to roentgenographic results surveying similar anatomic areas in 128 patients. This comparison revealed that roentgenographic interpretations were in error in 19% of the cases. Thirty-three patients had bone scans and roentgenograms that were in agreement and considered abnormal, but in more than one third of these cases the patients had multiple abnormalities that were shown by the bone scan but were not recognized roentgenographically. In consideration of the low toxicity, ready availability, economy, shortened procedure time, and low radiation dose associated with the use of these new bone-seeking agents, it is concluded that they are superior to roentgenograms and previously utilized radionuclides for early detection of osseous metastases.

Bone Neoplasms↗
PubMed2006

[Diadenosine polyphosphate analogue modulates signal transduction in hippocampal slices].

The modulatory effect of endogenous diadenosine polyphosphates on synaptic transmission in the rat hippocampal slices has been re-examined with a non-hydrolysable Ap4A analogue diadenosine-5',5'>>-P1,P4-[beta,gamma-methylene]tetraphosphate (AppCH2ppA). We have shown that AppCH2ppA at low micromolar concentrations induce inhibition of orthodromically evoked population spikes, without affecting of excitatory postsynaptic currents and antidromic spikes recorded in the CA1 zone of hippocampus. Such a spatially selective neuronal inhibition may influence dendritic electrogenesis in pyramidal neurons and consequently mediate control of neuronal network activity in hippocampus.

Action Potentials↗
PubMed2006

[Structure and performance of calcium polyphosphate for bone tissue engineering].

Porous calcium polyphosphate (CPP) has shown promise of tissue engineered implant application because of the biocompatibility and biodegradation. CPP with different polymerization degree were prepared by controlling the calcining time, and its polymerization degree could be calculated by developed method in this paper. Different crystal types CPP were prepared by quenching from the melt and crystallization of amorphous CPP. From the in vitro degradation, carried out in Tris-HCl buffer, the degradation velocity of CPP was controllable. The weight loss of CPP with different polymerization degrees and crystal types were different. With the increasing of polymerization degree, the weight loss during the degradation was decreasing, contrarily the strength of CPP was increasing. The amorphous CPP could degrade completely in 17 days while gamma-CPP do completely in 25 days. The degradation velocity beta-CPP and alpha-CPP was slower than gamma-CPP and the weight loss was about 12% and 5% respectively. The results of this study indicate that CPP have potential applications for bone tissue engineering as inorganic polymeric biomaterials.

Absorbable Implants↗
PubMed1991

Ca(2+)-insensitive modulation of a K+ conductance by inositol polyphosphates.

Macrophages derived from phorbol ester-induced human leukemic (HL-60) cells exhibit a voltage-activated inward rectifying potassium conductance which was modulated by macrophage colony-stimulating factor (Wieland, S. J., Chou, R. H., and Gong, Q. H. (1990) J. Cell. Physiol. 142, 643-651). Roles of intracellular messengers in this regulatory mechanism were investigated. Intracellular dialysis with inositol 1,3,4,5-tetrakisphosphate (IP4) or inositol 1,4,5-trisphosphate during tight-seal whole cell recording produced a rapid increase in the inward rectifying conductance. Changes in intracellular Ca2+ levels alone did not reproduce the stimulatory effect of these modulators. Intracellular dialysis with guanosine 5'-O-(thiotriphosphate) (GTP gamma S) resulted in profound inhibition of this conductance. These data suggest a novel cellular function for inositol polyphosphates, particularly IP4, and show antagonistic modulation with GTP gamma S on a human macrophage inward rectifier.

Calcium↗
PubMed1990

Influence of immobilization on properties of polyphosphate glucokinase.

Polyphosphate glucokinase from Mycobacterium tuberculosis H37Ra was covalently bound to the glutaraldehyde-activated collagen coating silica gel, to the nylon, and to the CNBr-activated Sepharose. After immobilization kinetic properties of the enzyme were altered.

Chromatography, Affinity↗
PubMed1990

The synthesis of inositol polyphosphates in rat liver by 5- and 6-kinase activities.

Amongst the array of known inositol phosphates, Ins(1,3,4)P3 is a pivotal intermediate. It can be attacked by two distinct phosphatases, and can also be phosphorylated at the 5- and 6-positions. The kinases that perform the latter reactions co-purified during anion-exchange chromatography; the 5-kinase accounted for 16% of the total kinase activity. The two resultant InsP4 isomers were identified by periodate oxidation, alkaline hydrolysis and specific enzyme assays. The phosphorylation of Ins(1,3,4)P3 to Ins(1,3,4,5)P4 may be important in coordinating calcium signalling. The production of Ins(1,3,4,6)P4 may provide a link between receptor-activated inositol phosphate production and the synthesis of InsP5 and InsP6, because Ins(1,3,4,6)P4 can itself be further phosphorylated. Two peaks of Ins(1,3,4,6)P4 kinase activity were separated by anion-exchange chromatography. One of these was a 5-kinase, and the other appeared to be a mixture of 5-kinase and 2-kinase activities. We investigated how the metabolism of Ins(1,3,4)P3 might be controlled in rat liver supernatant, which contained most of the hepatic Ins(1,3,4)P3 phosphatase and kinase activities. Ins(1,3,4)P3 phosphorylation was subject to kinetic restraints, such that the dephosphorylation pathway was greatly favoured. Moreover Ins(3,4,5,6)P4, which is itself an alternative precursor of InsP5, was a potent inhibitor of Ins(1,3,4)P3 kinase. We do not yet know the concentration of Ins(3,4,5,6)P4 in liver, although indirect evidence supports the idea that it is an endogenous inhibitor of Ins(1,3,4)P3 kinase. Our results illustrate the relationship between receptor-mediated inositol phosphate production and the synthesis of higher polyphosphates in rat liver, whilst also providing some insight into how this metabolic association is controlled.

Animals↗
PubMed1989

Different patterns of inositol polyphosphate production are seen in B lymphocytes after cross-linking of sIg by anti-Ig antibody or by a multivalent anti-Ig antibody dextran conjugate.

Anti-delta antibody conjugated to 2 x 10(6) m.w. dextran (dex) stimulates B lymphocyte proliferation at 10,000-fold lower concentrations than that required by the unconjugated antibody. Dex conjugated antibody also stimulates a greater and more sustained increase in intracellular ionized calcium [( Ca2+]i) than does the unconjugated anti-Ig antibody. Inasmuch as inositol phosphate metabolites have been linked to rises in [Ca2+]i, we analyzed by FPLC the relative amounts of the inositol polyphosphates (IP) in these cells. Anti-Ig-dextran induced a threefold greater increase in total IP than did the unconjugated anti-Ig. Furthermore, in cells stimulated by unconjugated anti-Ig there was a transient induction of I(1,4,5)P3 followed by a rapid accumulation of the I(1,3,4)P3 isomer with little accumulation of I(1,4)P2, whereas in anti-Ig-dex-stimulated cells there was prolonged elevation of I(1,4,5)P3 with more accumulation of I(1,4)P2. In addition, levels of I(1,3,4,5)P4 were maintained over a longer period of time in B cells stimulated by anti-Ig-dex than in those stimulated by unconjugated anti-Ig. The enhanced ratio of I(1,4,5)P3/I(1,3,4)P3 was also seen when suboptimal concentrations of anti-Ig-dex were used which stimulated a level of total inositol phosphate that was similar to that stimulated by the unconjugated anti-Ig. The possibility that the greater stimulation of increased [Ca2+] by anti-Ig-dex than by unconjugated anti-Ig was a predominant factor in influencing the metabolic pathway of I(1,4,5)P3 was excluded. These results show that 1) stimulation of increases in the various IP isomers occurs in anti-Ig stimulated normal B cells as has been shown in B cell lines and 2) that signal transduction and consequent PIP2 hydrolysis that is stimulated by Ag-mediated cross-linking of sIg is strongly influenced by the extent and type of cross-linking that is induced.

Animals↗