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  • 1
    Electronic Resource
    Electronic Resource
    Room-Temperature Short-Range Ordering in Fe-Si Alloys Observed by Internal Friction (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 137 (Mar. 2008), p. 83-90 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Research performed at Ghent University, regarding new production methods forelectrical steel, has shown that high silicon steel suffers an ageing phenomenon at roomtemperature. Recent studies carried out by the same group using different analysis techniques(Mossbauer spectroscopy, neutron diffraction, etc) brought to light a probable process of orderingtowards the D03-structure, which is responsible for the observed low ductility during cold rollingand makes the processing of steel extremely difficult. In addition, the Si-steels become more brittleas the delay time between hot and cold rolling is increased.Frequency dependent internal friction (FDIF) studies were performed on different Fe - Si alloyswith a Si content varying from 3.73 at. % to 8.7 at. % immediately after several thermal treatmentsand compared with ultra-low carbon steel. The evolution of relaxation peaks during the IFmeasurements, performed at constant room temperature, helps to understand the ageingmechanisms. Three processes have been observed: firstly, as expected, addition of Si reduces thecarbon Snoek peak. Secondly, a peak associated to C - Si is formed. Thirdly, a low frequency peakassociated with Zener relaxation (Si atom pairs) appears for a content of approximately 3.77 wt. %Si. The two latter peaks decrease with ageing time and in the case of the Zener peak there is anotable displacement to higher frequencies with a small increase of the Si content. The reduction ofthe peaks during the ageing after annealing is more noticeable in quenched specimens than in aircooled ones, and in furnace cooled specimens the reduction is even smaller, indicating that theprocess is really an ageing phenomenon.Room temperature short-range ordering might explain both the lowering of the Zener peak andthe observed macroscopic embrittlement
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.137.83.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    P2Y2 nucleotide receptor interaction with αV integrin mediates astrocyte migration (2005)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 95 (2005), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Astrocytes become activated in response to brain injury, as characterized by increased expression of glial fibrillary acidic protein (GFAP) and increased rates of cell migration and proliferation. Damage to brain cells causes the release of cytoplasmic nucleotides, such as ATP and uridine 5′-triphosphate (UTP), ligands for P2 nucleotide receptors. Results in this study with primary rat astrocytes indicate that activation of a G protein-coupled P2Y2 receptor for ATP and UTP increases GFAP expression and both chemotactic and chemokinetic cell migration. UTP-induced astrocyte migration was inhibited by silencing of P2Y2 nucleotide receptor (P2Y2R) expression with siRNA of P2Y2R (P2Y2R siRNA). UTP also increased the expression in astrocytes of αVβ3/5 integrins that are known to interact directly with the P2Y2R to modulate its function. Anti-αV integrin antibodies prevented UTP-stimulated astrocyte migration, suggesting that P2Y2R/αV interactions mediate the activation of astrocytes by UTP. P2Y2R-mediated astrocyte migration required the activation of the phosphatidylinositol-3-kinase (PI3-K)/protein kinase B (Akt) and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) signaling pathways, responses that also were inhibited by anti-αV integrin antibody. These results suggest that P2Y2Rs and their associated signaling pathways may be important factors regulating astrogliosis in brain disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2005.03408.x
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  • 3
    Electronic Resource
    Electronic Resource
    P2X7 nucleotide receptor activation enhances IFNγ-induced type II nitric oxide synthase activity in BV-2 microglial cells (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 87 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Under normal and pathological conditions, brain cells release nucleotides that regulate a wide range of cellular responses due to activation of P2 nucleotide receptors. In this study, the effect of extracellular nucleotides on IFNγ-induced NO release in murine BV-2 microglial cells was investigated. BV-2 cells expressed mRNA for metabotropic P2Y and ionotropic P2X receptors. Among the P2 receptor agonists tested, ATP, ADP, 2′,3′-O-(4-benzoylbenzoyl)-ATP (BzATP), and 2-methylthio-ATP (2-MeSATP), but not UTP, enhanced IFNγ-induced iNOS expression and NO production, suggesting that the uridine nucleotide receptors P2Y2 and P2Y6 are not involved in this response. U0126, an antagonist for MEK1/2, a kinase that phosphorylates the extracellular signal-regulated kinases ERK1/2, decreased IFNγ-induced NO production. BzATP, a potent P2X7 receptor agonist, was more effective than ATP, ADP, or 2-MeSATP at enhancing IFNγ-induced ERK1/2 phosphorylation. Consistent with activation of the P2X7 receptor, periodate-oxidized ATP, a P2X7 receptor antagonist, and suramin, a non-specific P2 receptor antagonist, inhibited the effect of ATP or BzATP on IFNγ-induced NO production, whereas pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), an antagonist of several P2X receptor subtypes, was ineffective. These results suggest that activation of P2X7 receptors may contribute to inflammatory responses in microglial cells seen in neurodegenerative diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.01995.x
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  • 4
    Electronic Resource
    Electronic Resource
    P2Y2 receptors activate neuroprotective mechanisms in astrocytic cells (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 91 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mechanical or ischemic trauma to the CNS causes the release of nucleotides and other neurotransmitters into the extracellular space. Nucleotides can activate nucleotide receptors that modulate the expression of genes implicated in cellular adaptive responses. In this investigation, we used human 1321N1 astrocytoma cells expressing a recombinant P2Y2 receptor to assess the role of this receptor in the regulation of anti-apoptotic (bcl-2 and bcl-xl) and pro-apoptotic (bax) gene expression. Acute treatment with the P2Y2 receptor agonist UTP up-regulated bcl-2 and bcl-xl, and down-regulated bax, gene expression. Activation of P2Y2 receptors was also coupled to the phosphorylation of cyclic AMP responsive element binding protein that positively regulates bcl-2 and bcl-xl gene expression. Cyclic AMP responsive element decoy oligonucleotides markedly attenuated the UTP-induced increase in bcl-2 and bcl-xl mRNA levels. Activation of P2Y2 receptors induced the phosphorylation of the pro-apoptotic factor Bad and caused a reduction in bax/bcl-2 mRNA expression ratio. All these signaling pathways are known to be involved in cell survival mechanisms. Using cDNA microarray analysis and RT–PCR, P2Y2 receptors were found to up-regulate the expression of genes for neurotrophins, neuropeptides and growth factors including nerve growth factor 2; neurotrophin 3; glia-derived neurite-promoting factor, as well as extracellular matrix proteins CD44 and fibronectin precursor – genes known to regulate neuroprotection. Consistent with this observation, conditioned media from UTP-treated 1321N1 cells expressing P2Y2 receptors stimulated the outgrowth of neurites in PC-12 cells. Taken together, our results suggest an important novel role for the P2Y2 receptor in survival and neuroprotective mechanisms under pathological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2004.02699.x
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  • 5
    Electronic Resource
    Electronic Resource
    IgG class antibodies from psoriasis patients recognize the 60-KDa heat-shock protein of Streptococcus pyogenes (2004)
    Oxford, UK : Blackwell Science Ltd
    International journal of dermatology 43 (2004), S. 0 
    Details
    ISSN: 1365-4632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  We have previously found that psoriatic patients have IgG autoantibodies that recognize lesions but not autologous normal skin. The reactivity of the autoantibodies can be adsorbed with streptococcal antigens.Methods  IgG antibodies were determined by immunoblot and ELISA to streptococcal antigens and by ELISA to the recombinants HSP60Sp, HSP70Sp, HSP60Ec and HSP60Hu, in plaque (PP) and guttate (GP) psoriasis patients, in healthy subjects (HC) and in individuals with streptococcal throat infections and high ASO titers, but without history of dermatological disease (ISp).Results  We found by immunoblot that the IgG response to 71-, 60-, and 14-kDa protein fractions of Streptococcus pyogenes is important in psoriasis. We also found by ELISA that the response to the rHSP60Sp in PP was higher than in all the other three groups studied (P 〈 0.05) with an odds ratio of 11.11 (CI95% of 4.33–28.49). The PP infected with S. pyogenes had higher titers of the antirHSP60Sp, high ASO, and high PASI. The PP patients did not significantly recognize the HSP60Ec or the HSP60Hu. The GP patients had a higher response to the rHSP60Sp than the healthy controls or ISp patients (P 〈 0.05) but showed no association with the disease. The response of the ISp patients to the HSP60Sp was similar to the healthy controls. The response to the rHSP70Sp was similar in the PP patients and the healthy controls.Conclusion  Results suggest that a high response to the HSP60Sp could be associated with the chronic form of psoriasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-4632.2004.01884.x
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  • 6
    Electronic Resource
    Electronic Resource
    THE USE OF PHOTOIDENTIFICATION TO STUDY THE AMAZON RIVER DOLPHIN, INIA GEOFFRENSIS, IN THE COLOMBIAN AMAZON (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 10 (1994), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1994.tb00489.x
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  • 7
    Electronic Resource
    Electronic Resource
    Differential agonist-induced desensitization of P2Y2 nucleotide receptors by ATP and UTP (2000)
    Springer
    Molecular and cellular biochemistry 206 (2000), S. 75-89 
    Details
    ISSN: 1573-4919
    Keywords: P2 nucleotide receptors ; intracellular calcium mobilization ; receptor desensitization ; individual cell measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The equal potency and efficacy of the agonists, ATP and UTP, pharmacologically distinguish the P2Y2 receptor from other nucleotide receptors. Investigation of the desensitization of the P2Y2 receptors is complicated by the simultaneous expression of different P2 nucleotide receptor subtypes. The co-expression of multiple P2 receptor subtypes in mammalian cells may have led to contradictory reports on the efficacy of the natural agonists of the P2Y2 receptor to induce desensitization. We decided to investigate the desensitization of human and murine isoforms of the P2Y2 receptor, and to rigorously examine their signaling and desensitization properties. For these purposes, we used 1321N1 astrocytoma cells stably transfected with the human or murine P2Y2 receptor cDNA, as well as human A431 cells that endogenously express the receptor. The mobilization of intracellular calcium by extracellular nucleotides was used as a functional assay for the P2Y2 receptors. While ATP and UTP activated the murine and human P2Y2 receptors with similar potencies (EC50 values were 1.5-5.8 μM), ATP was ~ 10-fold less potent (IC50 = 9.1-21.2 μM) than UTP (IC50 = 0.7-2.9 μM) inducing homologous receptor desensitization in the cell systems examined. Individual cell analyses of the rate and dose dependency of agonist-induced desensitization demonstrated that the murine receptor was slightly more resistant to desensitization than its human counterpart. To our knowledge, this is the first individual cell study that has compared the cellular heterogeneity of the desensitized states of recombinant and endogenously expressed receptors. This comparison demonstrated that the recombinant system conserved the cellular regulatory elements needed to attenuate receptor signaling by desensitization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007091127392
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  • 8
    Electronic Resource
    Electronic Resource
    Inhibition of human topoisomerase II by anti-neoplastic benzazolo[3,2-a]quinolinium chlorides (1998)
    Springer
    Molecular and cellular biochemistry 178 (1998), S. 203-212 
    Details
    ISSN: 1573-4919
    Keywords: antitumor ; DNA intercalator ; cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Previously we reported [20] that there is no correlation between the cytotoxic activity of four new structural analogs of the antitumor DNA intercalator 3-nitrobenzothiazolo[3,2-a]quinolinium chloride (NBQ-2) and their interaction with DNA. In the present study, we present evidence suggesting that the molecular basis for the anti-proliferative activity of these drugs is the inhibition of topoisomerase II. The NBQ-2 derivatives inhibited the relaxation of supercoiled DNA plasmid pRYG mediated by purified human topoisomerase II. Inhibition of the decatenation of kinetoplast DNA mediated by partially purified topoisomerase II extracted from the human histiocytic lymphoma U937 (a cell line previously shown to be sensitive to the drugs) was also caused by these drugs. The potency of the benzazolo[3,2-a]quinolinium drugs against topoisomerase II in vitro was the following: 7-(1-propenyl)-3-nitrobenzimidazolo[3,2-a]quinolinium chloride (NBQ-59) 〉 4-chlorobenzothiazolo[3,2-a]quinolinium chloride (NBQ-76) 〉 7-ethyl-3-nitrobenzimidazolo[3,2-a]quinolinium chloride (NBQ-48) 〉 7-benzyl-3-nitrobenzimidazolol[3,2-a]quinolinium chloride (NBQ-38). This rank of potency for topoisomerase II inhibition correlated very well with the cytotoxicity elicited by these drugs. Furthermore, significant levels of topoisomerase II/DNA cleavage complex induced by these drugs in vivo were detected when U937 cells were treated with NBQ-59 and NBQ-76 whereas NBQ-38 and NBQ-38 and NBQ-48 produced negligible amounts of the cleavage complex. Our results strongly suggest that topoisomerase II is the major cellular target of this family of compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006847615575
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanisms of agonist-dependent and -independent desensitization of a recombinant P2Y2 nucleotide receptor (2000)
    Springer
    Molecular and cellular biochemistry 205 (2000), S. 115-123 
    Details
    ISSN: 1573-4919
    Keywords: cystic fibrosis ; uridine 5′-triphosphate ; 1321N1 astrocytoma ; HT-29 epithelial cells ; protein kinase C isoforms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract UTP activates P2Y2 receptors in both 1321N1 cell transfectants expressing the P2Y2 receptor and human HT-29 epithelial cells expressing endogenous P2Y2 receptors with an EC50 of 0.2- 1.0 μM. Pretreatment of these cells with UTP diminished the effectiveness of a second dose of UTP (the IC50 for UTP-induced receptor desensitization was 0.3 - 1.0 μM for both systems). Desensitization and down-regulation of the P2Y2 nucleotide receptor may limit the effectiveness of UTP as a therapeutic agent. The present studies investigated the phenomenon of P2Y2 receptor desensitization in human 1321N1 astrocytoma cells expressing recombinant wild type and C-terminal truncation mutants of the P2Y,2 receptor. In these cells, potent P2Y2 receptor desensitization was observed after a 5 min exposure to UTP. Full receptor responsiveness returned 5-10 min after removal of UTP. Thapsigargin, an inhibitor of Ca2+-ATPase in the endoplasmic reticulum, induced an increase in the intracellular free calcium concentration, [Ca2+]i, after addition of desensitizing concentrations of UTP, indicating that P2Y2 receptor desensitization is not due to depletion of calcium from intracellular stores. Single cell measurements of increases in [Ca2+]i induced by UTP in 1321N1 cell transfectants expressing the P2Y2 receptor indicate that time- and UTP concentration-dependent desensitization occurred uniformly across a cell population. Other results suggest that P2Y2 receptor phosphorylation/dephosphorylation regulate receptor desensitization/resensitization. A 5 min preincubation of 1321N1 cell transfectants with the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), reduced the subsequent response to UTP by about 50% whereas co-incubation of PMA with UTP caused a greater inhibition in the response. The protein phosphatases - 1 and -2A inhibitor, okadaic acid, partially blocked resensitization of the receptor. Furthermore, C-terminal truncation mutants of the P2Y2 receptor that eliminated several potential phosphorylation sites including two for PKC were resistant to UTP-, but not phorbol ester-induced desensitization. Down regulation of protein kinase C isoforms prevented phorbol ester-induced desensitization but had no effect on agonist-induced desensitization of wild type or truncation mutant receptors. These results suggest that phosphorylation of the C-terminus of the P2Y2 receptor by protein kinases other than protein kinase C mediates agonist-induced receptor desensitization. A better understanding of the molecular mechanisms of P2Y2 nucleotide receptor desensitization may help optimize a promising cystic fibrosis pharmacotherapy based on the activation of anion secretion in airway epithelial cells by P2Y2 receptor agonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007018001735
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  • 10
    Electronic Resource
    Electronic Resource
    Dna binding-independent anti-proliferative action of benzazolo[3,2-α]quinolinium DNA intercalators (1997)
    Springer
    Molecular and cellular biochemistry 177 (1997), S. 69-77 
    Details
    ISSN: 1573-4919
    Keywords: molecular mechanism of drug action ; DNA-drug interaction ; anti-neoplastic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The proposed mechanism of action of the antineoplastic drug 3-nitrobenzothiazolo[3,2-& agr;]quinolinium chloride (NBQ-2) involves its interaction with DNA by intercalation and inhibition of topoisomerase II activity by arresting the enzyme in a covalent cleavage complex. In an attempt to identify some structural determinants for activity and develop a molecular structure/cytotoxicity correlation, four new structural analogs of the antitumor NBQ-2 were prepared and their cytotoxic activity and DNA binding properties were investigated. The cytotoxic activity was evaluated against six different human tumor cell lines: U937, K-562, HL-60, HT-29, HeLa, and A431. The results showed that these new drugs elicit pronounced cytotoxic effects against U937, K-562, HL-60 and A431 while HeLa and HT-29 were less sensitive to the new drugs. This apparent selectivity was different to that of m-AMSA, a drug currently used for cancer treatment. Since the interaction of NBQ-2 to DNA by intercalation has been proposed as the initial step leading to its antineoplastic activity, DNA binding and changes in DNA contour length induced by the new NBQ-2 structural analogs were also investigated using calf thymus and human DNA. The drug, 7-(1-propenyl)-3-nitrobenzimidazolo[3,2-& agr;]quinolinium chloride (NBQ-59) was the most cytotoxic agent of the analog series (IC50 = 16 & mgr;M for HL-60 cells), however, it demonstrated the weakest binding to DNA (Kint = 0.9 × 105 M-1 for calf thymus DNA). NBQ-59 was also found to be a poor intercalator into the DNA double helix. Therefore, our results suggest that DNA binding is not the primary mechanism of drug action for this family of compounds. In addition structural determinants important for cytotoxicity of the benzazolo quinolinium chlorides were suggested by our results. In particular, the nitro group in the 3 position does not seem to be necessary for bioactivity, while substitutions in the benzazolo moiety have striking effects on the biological activity of the drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006857118469
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