Showing papers on "Vanadate published in 2003"
TL;DR: Improved sensitivity to insulin in liver and muscle tissues of Type II diabetic patients following vanadium therapy was observed as well, and the potential usage of vanadium in the future care of diabetes in human depends on manipulations that would elevate the insulinomimetic efficacy ofVanadium without increasing its toxicity.
212 citations
TL;DR: Shewanella oneidensis couples anaerobic oxidation of lactate, formate, and pyruvate to the reduction of vanadium pentoxide to precipitate as a VIV-containing solid.
Abstract: Shewanella oneidensis couples anaerobic oxidation of lactate, formate, and pyruvate to the reduction of vanadium pentoxide (V(V)). The bacterium reduces V(V) (vanadate ion) to V(IV) (vanadyl ion) in an anaerobic atmosphere. The resulting vanadyl ion precipitates as a V(IV)-containing solid.
138 citations
TL;DR: Using the human lung alveolar epithelial cancer cell line A549, the role of reactive oxygen species (ROS), extracellular signal-regulated protein kinases (ERK), and p38 protein kinase in vanadate-induced cell growth arrest is investigated.
137 citations
TL;DR: Despite the complexity of the substrate of this phosphodiesterase, vanadate succeeded in linking human Tdp1, a tyrosine-containing peptide, and a single-stranded DNA oligonucleotide into a quaternary complex that mimics the transition state for the first step of the catalytic reaction.
121 citations
TL;DR: In this paper, the role of the protein environment via supramolecular interactions for both structure and function of the related enzymatic systems is discussed, and the relevance of cis-dioxovanadium(V) complexes with the versatile tridentate N -salicylidenehydrazide ligand system as models is discussed.
95 citations
TL;DR: The higher uptake of the vanadyl complexes and the observed changes of membrane proteins might attribute to their insulin-mimetic mechanisms and toxicities, and the lifetime of vanadium complexes might be prolonged in physiological fluids.
93 citations
TL;DR: It is proposed that in order for the catalytic transition state to form, the two nucleotide-binding domains dimerize to form an integrated single entity containing two bound ATP with just one of the two ATP being hydrolyzed per dimerization event.
90 citations
TL;DR: It is proposed that SSAO activity and vanadate potently mimic insulin effects in adipose cells and exert an anti-diabetic action in an animal model of type 1 diabetes mellitus.
73 citations
TL;DR: In this article, a defect structure derived from combined X-ray and neutron powder diffraction studies was used to accurately predict solid solution limits in divalent-substituted BIMEVOXes.
62 citations
TL;DR: It is proposed that benzylamine/vanadate administration generates peroxovanadium locally in pancreatic islets, which stimulates insulin secretion and also produces peroxovadium in adipose tissue, activating glucose metabolism in adipocytes and in neighboring muscle.
Abstract: In this study we have explored whether the bifunctional protein semicarbazide-sensitive amine oxidase (SSAO)/vascular adhesion protein-1 (VAP-1) represents a novel target for type 2 diabetes. To this end, Goto-Kakizaki (GK) diabetic rats were treated with the SSAO substrate benzylamine and with low ineffective doses of vanadate previously shown to have antidiabetic effects in streptozotocin-induced diabetic rats. The administration of benzylamine in combination with vanadate in type 2 diabetic rats acutely stimulated glucose tolerance, and the chronic treatment normalized hyperglycemia, stimulated glucose transport in adipocytes, and reversed muscle insulin resistance. Acute in vivo administration of benzylamine and vanadate stimulated skeletal muscle glucose transport, an effect that was also observed in incubated muscle preparations coincubated with adipose tissue explants or with human recombinant SSAO. Acute administration of benzylamine/vanadate also ameliorated insulin secretion in diabetic GK rats, and this effect was also observed in incubated pancreatic islets. In keeping with these observations, we also demonstrate that pancreatic islets express SSAO/VAP-1. As far as mechanisms of action, we have found that benzylamine/vanadate causes enhanced tyrosine phosphorylation of proteins and reduced protein tyrosine phosphatase activity in adipocytes. In addition, incubation of human recombinant SSAO, benzylamine, and vanadate generates peroxovanadium compounds in vitro. Based on these data, we propose that benzylamine/vanadate administration generates peroxovanadium locally in pancreatic islets, which stimulates insulin secretion and also produces peroxovanadium in adipose tissue, activating glucose metabolism in adipocytes and in neighboring muscle. This opens the possibility of using the SSAO/VAP-1 activity as a local generator of protein tyrosine phosphatase inhibitors in antidiabetic therapy.
57 citations
TL;DR: Results suggest that release of drug from the transporter during the catalytic cycle precedes formation of the transition state of P-glycoprotein, and the drug binding affinity of the ADP-bound form of the transporter was also comparable to that of the unoccupied transporter.
Abstract: The P-glycoprotein multidrug transporter is a plasma membrane efflux pump for hydrophobic natural products, drugs, and peptides, driven by ATP hydrolysis. Determination of the details of the catalytic cycle of P-glycoprotein is critical if we are to understand the mechanism of drug transport and design ways to inhibit it. It has been proposed that the vanadate-trapped transition state of P-glycoprotein (Pgp·ADP·Vi·M2+, where M2+ is a divalent metal ion) has a very low affinity for drugs compared to resting state protein, thus leading to binding of substrate on the cytoplasmic side of the membrane and release of substrate to the extracellular medium (or the extracellular membrane leaflet). We have used several different fluorescence spectroscopic approaches to show that isolated purified P-glycoprotein, when trapped in a stable transition state with vanadate and either Co2+or Mg2+, binds drugs with high affinity. For vinblastine, colchicine, rhodamine 123, and doxorubicin, the affinity of the vanadate-trap...
TL;DR: Results suggest that TreVO could be a potential candidate for therapeutic treatments, and a new vanadium complex of the vanadyl(IV) cation with the disaccharide trehalose (TreVO), Na6[VO(Tre)2].
Abstract: Vanadium compounds show interesting biological and pharmacological properties. Some of them display insulin-mimetic effects and others produce anti-tumor actions. The bioactivity of vanadium is present in inorganic species like the vanadyl(IV) cation or vanadate(V) anion. Nevertheless, the development of new vanadium derivatives with organic ligands which improve the beneficial actions and decrease the toxic effects is of great interest. On the other hand, the mechanisms involved in vanadium bioactivity are still poorly understood. A new vanadium complex of the vanadyl(IV) cation with the disaccharide trehalose (TreVO), Na6[VO(Tre)2].4H2O, here reported, shows interesting insulin-mimetic properties in two osteoblast cell lines, a normal one (MC3T3E1) and a tumoral one (UMR106). The complex affected the proliferation of both cell lines in a different manner. On tumoral cells, TreVO caused a weak stimulation of growth at 5 μM but it inhibited cell proliferation in a dose-response manner between 50 and 100 μM. TreVO significantly inhibited UMR106 differentiation (15–25% of basal) in the range 5–100 μM. On normal osteoblasts, TreVO behaved as a mitogen at 5–25 μM. Different inhibitors of the MAPK pathway blocked this effect. At higher concentrations (75–100 μM), the complex was a weak inhibitor of the MC3T3E1 proliferation. Besides, TreVO enhanced glucose consumption by a mechanism independent of the PI3-kinase activation. In both cell lines, TreVO stimulated the ERK phosphorylation in a dose- and time-dependent manner. Different inhibitors (PD98059, wortmannin, vitamins C and E) partially decreased this effect, which was totally inhibited by their combination. These results suggest that TreVO could be a potential candidate for therapeutic treatments.
TL;DR: In this paper, a novel organic-inorganic hybrid compound [Cu(phen)]2[VIVV4VAs2VO19]·0.5H2O 1 has been hydrothermally synthesized.
Abstract: A novel organic–inorganic hybrid compound [Cu(phen)]2[VIVV4VAs2VO19]·0.5H2O 1 has been hydrothermally synthesized. Its structure, determined by single crystal X-ray diffraction, exhibits an unusual two-dimensional arsenic vanadate layered network grafted with the [Cu(phen)]2+ complex. The chelating phen ligands project perpendicularly beyond the inorganic layer. Variable temperature magnetic susceptibility studies indicate that both ferro- and antiferro-magnetic interactions exist in 1.
TL;DR: The enzyme was purified 1727-fold to apparent homogeneity from apple leaves with a maximal specific activity of 89.8 μmol min−1 mg−1 protein measured at 2 mM sorbitol-6-phosphate (sorbitol- 6-P).
TL;DR: JNK signaling plays a major role in vanadate-mediated activation of the Fas-FADD-caspase-8 pathway that accounts for vanadATE-induced apoptosis of CGPs.
TL;DR: The structural behavior of oxygen environments of Pb2+ cations in binary lead oxide glasses was studied by X-ray diffraction using high-energy photons from a synchrotron as discussed by the authors.
Abstract: The structural behavior of oxygen environments of Pb2+ cations in binary lead oxide glasses is studied by X-ray diffraction using high-energy photons from a synchrotron. Samples of different PbO content and of different type of network-forming oxide such as SiO2 and V2O5 are used. For comparison, earlier data obtained of Pb phosphate glasses are included. The oxygen environments strongly depend on the type of network-forming oxide but they do not vary with PbO content. Numbers and distances of oxygen atoms at the shortest separations are three, four and five with lengths of 0.230, 0.252 and 0.247 nm for glasses with SiO2, V2O5 and P2O5, respectively. The numbers of further oxygen atoms at distances of ∼0.275 nm are about one, two and three. The excentric positions of Pb2+ cations in the oxygen environments of silicate and vanadate networks are attributed to non-uniform distributions of negative charge on the surrounding oxygen atoms. In case of lead vanadate glasses the Pb2+ cations stabilize VO5 units which is not known of vanadate glasses of other network-modifying oxides MeO.
TL;DR: It is suggested that alteration of the kinase-phosphatase equilibrium during OM and the MAT leads to cytogenetic abnormalities that differ between oocytes and bone marrow cells.
Abstract: Protein tyrosine phosphatases are needed for activating maturation promoting factor, meiotic spindle assembly and spindle checkpoint inactivation. The protein phosphatase inhibitor vanadate was used to upset the kinase-phosphatase equilibrium during oocyte maturation (OM) and the metaphase anaphase transition (MAT) prior to cytogenetic analyses of mouse oocytes and bone marrow cells. ICR females received pregnant mare serum gonadotrophin (PMSG) and 48h later received human chorionic gonadotrophin (hCG). Vanadate doses of 0, 5, 15, and 25mg/kg were administered intraperitoneally immediately after hCG and ovulated oocytes and bone marrow cells were processed for cytogenetic analyses 18h after hCG. Data were analyzed by Chi-square and Fisher's exact tests. Vanadate induced different cytogenetic abnormalities in oocytes and in bone marrow cells. The frequencies of oocytes exhibiting premature anaphase (spontaneous activation) in vanadate exposed mice were significantly (P<0.01) elevated over controls; whereas, in bone marrow cells, the levels of tetraploidy, hyperploidy and premature centromere separation were significantly (P<0.01) increased by vanadate treatment. These results suggest that alteration of the kinase-phosphatase equilibrium during OM and the MAT leads to cytogenetic abnormalities that differ between oocytes and bone marrow cells.
TL;DR: There is single-site turnover occurring in the E552Q and E1197Q mutants and that ADP release from the mutant site, or another catalytic step, is impaired in these mutants, which support a model in which the two NBDs of P-gp are not functionally equivalent.
Abstract: In the nucleotide-binding domains (NBDs) of ABC transporters, such as mouse Mdr3 P-glycoprotein (P-gp), an invariant carboxylate residue (E552 in NBD1; E1197 in NBD2) immediately follows the Walker B motif (hyd4DE/D). Removal of the negative charge in mutants E552Q and E1197Q abolishes drug-stimulated ATPase activity measured by Pi release. Surprisingly, drug-stimulated trapping of 8-azido-[α-32P]ATP is still observed in the mutants in both the presence and absence of the transition-state analogue vanadate (Vi), and ADP can be recovered from the trapped enzymes. The E552Q and E1197Q mutants show characteristics similar to those of the wild-type (WT) enzyme with respect to 8-azido-[α-32P]ATP binding and 8-azido-[α-32P]nucleotide trapping, with the latter being both Mg2+ and temperature dependent. Importantly, drug-stimulated nucleotide trapping in E552Q is stimulated by Vi and resembles the WT enzyme, while it is almost completely Vi insensitive in E1197Q. Similar nucleotide trapping properties are observe...
TL;DR: Vanadate anion catalyses aerobic hydroxylation of hydrocarbons in acetonitrile in the presence of solid ascorbic acid or zinc and with obligatory participation of pyridine, pyrazine-2-carboxylic acid and acetic acid as mediators of proton and electron transfer as mentioned in this paper.
Abstract: Vanadate anion catalyses aerobic hydroxylation of hydrocarbons in acetonitrile in the presence of solid ascorbic acid or zinc and with obligatory participation of pyridine, pyrazine-2-carboxylic acid and acetic acid as mediators of proton and electron transfer. If sufficient amount of water is present in the reaction mixture, ascorbic acid is dissolved in aqueous acetonitrile and no hydroxylation occurs in this case. The dependencies of the product yields on the concentrations of the reactants have been studied and a mechanism of the formation of hydroxyl radicals has been proposed. These systems mimic generation of hydroxyl radicals in certain vanadium-dependent biological processes.
TL;DR: It is demonstrated that preincubation with low vanadate concentrations (25-75 microM) induces a dose-dependent increase in glucose uptake, and inhibition of PI 3-kinase or p38 MAPK by wortmannin and PD-169316, respectively, significantly inhibitedVanadate-mediated glucose uptake in cardiomyocytes.
Abstract: Vanadate, an inhibitor of tyrosine phosphatases, has insulin-mimetic properties. It has been shown that acute vanadate administration enhances glucose uptake independently of phosphatidylinositol (...
TL;DR: It is concluded that the increase in H. didactylus methaemoglobin reductase activity is more pronounced upon exposition to 'metavanadate' than to cadmium and decameric species, suggesting that vanadate speciation is important to evaluate in vivo and in vitro effects on methaenoglobin reduCTase activity.
TL;DR: In this paper, the authors applied dynamic reaction cell (DRC) technology in the context of the speciation analysis of vanadium at therapeutic levels in serum, which was necessary in order to detect vanadium on-line after size-exclusion chromatography with a buffer at physiological salinity.
Abstract: Dynamic reaction cell (DRC) technology was applied in the context of the speciation analysis of vanadium at therapeutic levels in serum This technology was necessary in order to detect vanadium on-line after size-exclusion chromatography with a buffer at physiological salinity (015 M NaCl) This salinity was compulsory to assure the stability of the vanadium compounds during chromatography, in other words to prevent inter-species conversion In fact, the DRC allowed the detection of vanadium without adapting the conditions of the chromatographic separation to ICP-MS First, the merits of various reaction gases were compared: methane, carbon monoxide, ammonia, oxygen and the combination of argon (collision gas) and hydrogen (reaction gas) In each instance, the reaction cell parameters were optimised in order to obtain the lowest detection limit for 51V (as 51V+or as 51V16O+ with O2 as the reaction gas) in chlorine-rich solution, Cl being the parent element of the 35Cl16O+ interference Ammonia was found to offer the best detection limit (3s criterion, 10 ng L−1 with pneumatic nebulisation as the sample introduction system) The detection limit with size-exclusion chromatography-ICP-DRC-MS for vanadate, expected to be the worst among all vanadium chemical species, was found to be 40 ng L−1 serum (or 4 pg V, 100 µL serum injected) and the repeatability 7% This on-line separation method was used in order to speciate vanadium in serum after incubation with vanadate, at a concentration level that is representative of the pharmacological concentration range of vanadium when used as an insulin-like agent
TL;DR: The finding suggests that ERK activation plays an active role in mediating EGCG plus vanadate-induced apoptosis of U937 cells and functions upstream of caspase activation to initiate the apoptotic signal.
TL;DR: The results support the hypothesis that domain A of the Na+,K+-ATPase is isolated in the E 1 form, but contributes to make up the catalytic site inThe E 2 and E 2P conformations.
TL;DR: In this paper, the authors describe the presence of an external phosphatase activity in intact bloodstream forms of T. brucei, with p-nitrophenyl phosphate (pNPP) as substrate, linearly for up to at least 30 min.
Abstract: Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [(32)P]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. In this work, we describe the presence of an external phosphatase activity in intact bloodstream forms of T. brucei. With p-nitrophenyl phosphate (pNPP) as substrate, these intact cells produced 3-5 nmol pNP min(-1) mg(-1), linearly for up to at least 30 min. The activity was not significantly increased by Mg(2+), Mn(2+), Ca(2+) and Co(2+), but was inhibited by vanadate, NaF, p-chloromercuribenzoate and Zn(2+) and was insensitive to okadaic acid. Membrane-enriched fractions of parasites contained an acid phosphatase activity, with a pH optimum in the range of 4.5-5.5. This activity hydrolyzed phosphotyrosine (40 nmol phosphate min(-1) mg(-1)) better than phosphothreonine or phosphoserine. Partial purification of this phosphatase yielded a single activity band following gel electrophoresis, a K(m) value of 0.29 mM with pNPP and was insensitive to the Fe(2+)/H(2)O(2)/ascorbate system.
TL;DR: In this paper, a synthetic form of the mineral hewettite was prepared via a new route in aqueous medium, starting either from the crystalline compound Li 1.1V3O8, or from its amorphous precursor.
TL;DR: PCALC36, a new molecule with a non-steroidal skeleton, inhibits the Na(+),K(+)-ATPase by a mechanism of action different from the cardiac glycosides and could thus serve as a structural paradigm to develop new inotropic drugs.
TL;DR: Magnesium orthovanadate crystals with a well-defined crystallographic orientation have been grown successfully in a four-mirror optical floating zone furnace as discussed by the authors, and the crystals grow well.
Abstract: Magnesium orthovanadate crystals (< Φ 5 mm × L 55 mm) with a well-defined crystallographic orientation have been grown successfully in a four-mirror optical floating zone furnace. The crystals grow...
TL;DR: In this article, vanadate complexes of α-hydroxycarboxylic acids form readily and reversibly in aqueous solution, and α-Hydroxyisobutyric acid forms three major products with 1:1, 2:2 and 2:3 ligand to vanadium stoichiometries.
TL;DR: A membrane protein in S. mutans is described, with a molecular weight of 100 kDa, which exhibits ATPase activity inhibited by classic inhibitors of P-type ATPases (orthovanadate) and H(+),K(+)-ATPase (lanzoprazole), and undergoes phosphorylation during the catalytic reaction, like that of H( +),ion-ATPases described in yeast and plant plasma membrane.