The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Chunyue Duan - One of the best experts on this subject based on the ideXlab platform.
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3d characterization of morphological changes in the intervertebral disc and endplate during aging a Propagation Phase contrast synchrotron micro tomography study
Scientific Reports, 2017Co-Authors: Yong Cao, Shenghui Liao, Hao Zeng, Francis Tintani, Yongqiang Hao, Lei Wang, Chunyue DuanAbstract:A better understanding of functional changes in the intervertebral disc (IVD) and interaction with endplate is essential to elucidate the pathogenesis of IVD degeneration disease (IDDD). To date, the simultaneous depiction of 3D micro-architectural changes of endplate with aging and interaction with IVD remains a technical challenge. We aim to characterize the 3D morphology changes of endplate and IVD during aging using PPCST. The lumbar vertebral level 4/5 IVDs harvested from 15-day-, 4- and 24-month-old mice were initially evaluated by PPCST with histological sections subsequently analyzed to confirm the imaging efficiency. Quantitative assessments of age-related trends after aging, including mean diameter, volume fraction and connectivity of the canals, and endplate porosity and thickness, reached a peak at 4 months and significantly decreased at 24 months. The IVD volume consistently exhibited same trend of variation with the endplate after aging. In this study, PPCST simultaneously provided comprehensive details of 3D morphological changes of the IVD and canal network in the endplate and the interaction after aging. The results suggest that PPCST has the potential to provide a new platform for attaining a deeper insight into the pathogenesis of IDDD, providing potential therapeutic targets.
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correction corrigendum 3d visualization of the lumbar facet joint after degeneration using Propagation Phase contrast micro tomography
Scientific Reports, 2016Co-Authors: Yong Cao, Yi Zhang, Xianzhen Yin, Chunyue DuanAbstract:Scientific Reports 6: Article number: 21838; Published online: 24 February 2016; updated: 09 May 2016 The original version of this Article contained a typographical error in the spelling of the author Xianzhen Yin, which was incorrectly given as Xianzheng Yin. This has now been corrected in the PDF and HTML versions of the Article.
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3d visualization of the lumbar facet joint after degeneration using Propagation Phase contrast micro tomography
Scientific Reports, 2016Co-Authors: Yong Cao, Yi Zhang, Xianzheng Yin, Chunyue DuanAbstract:Lumbar facet joint (LFJ) degeneration is believed to be an important cause of low back pain (LBP). Identifying the morphological changes of the LFJ in the degeneration process at a high-resolution level could be meaningful for our better understanding of the possible mechanisms underlying this process. In the present study, we determined the 3D morphology of the LFJ using Propagation Phase contrast micro-tomography (PPCT) in rats to assess the subtle changes that occur during the degeneration process. PPCT provides vivid 3D images of micromorphological changes in the LFJ during its degeneration process, and the changes in the subchondral bone occurred earlier than in the cartilage during the early stage of degeneration of the LFJ. The delineation of this alteration was similar to that with the histological method. Our findings demonstrated that PPCT could serve as a valuable tool for 3D visualization of the morphology of the LFJ by providing comprehensive information about the cartilage and the underlying subchondral bone and their changes during degeneration processes. It might also have great potential for providing effective diagnostic tools to track changes in the cartilage and to evaluate the effects of therapeutic interventions for LFJ degeneration in preclinical studies.
Yong Cao - One of the best experts on this subject based on the ideXlab platform.
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3d characterization of morphological changes in the intervertebral disc and endplate during aging a Propagation Phase contrast synchrotron micro tomography study
Scientific Reports, 2017Co-Authors: Yong Cao, Shenghui Liao, Hao Zeng, Francis Tintani, Yongqiang Hao, Lei Wang, Chunyue DuanAbstract:A better understanding of functional changes in the intervertebral disc (IVD) and interaction with endplate is essential to elucidate the pathogenesis of IVD degeneration disease (IDDD). To date, the simultaneous depiction of 3D micro-architectural changes of endplate with aging and interaction with IVD remains a technical challenge. We aim to characterize the 3D morphology changes of endplate and IVD during aging using PPCST. The lumbar vertebral level 4/5 IVDs harvested from 15-day-, 4- and 24-month-old mice were initially evaluated by PPCST with histological sections subsequently analyzed to confirm the imaging efficiency. Quantitative assessments of age-related trends after aging, including mean diameter, volume fraction and connectivity of the canals, and endplate porosity and thickness, reached a peak at 4 months and significantly decreased at 24 months. The IVD volume consistently exhibited same trend of variation with the endplate after aging. In this study, PPCST simultaneously provided comprehensive details of 3D morphological changes of the IVD and canal network in the endplate and the interaction after aging. The results suggest that PPCST has the potential to provide a new platform for attaining a deeper insight into the pathogenesis of IDDD, providing potential therapeutic targets.
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correction corrigendum 3d visualization of the lumbar facet joint after degeneration using Propagation Phase contrast micro tomography
Scientific Reports, 2016Co-Authors: Yong Cao, Yi Zhang, Xianzhen Yin, Chunyue DuanAbstract:Scientific Reports 6: Article number: 21838; Published online: 24 February 2016; updated: 09 May 2016 The original version of this Article contained a typographical error in the spelling of the author Xianzhen Yin, which was incorrectly given as Xianzheng Yin. This has now been corrected in the PDF and HTML versions of the Article.
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3d visualization of the lumbar facet joint after degeneration using Propagation Phase contrast micro tomography
Scientific Reports, 2016Co-Authors: Yong Cao, Yi Zhang, Xianzheng Yin, Chunyue DuanAbstract:Lumbar facet joint (LFJ) degeneration is believed to be an important cause of low back pain (LBP). Identifying the morphological changes of the LFJ in the degeneration process at a high-resolution level could be meaningful for our better understanding of the possible mechanisms underlying this process. In the present study, we determined the 3D morphology of the LFJ using Propagation Phase contrast micro-tomography (PPCT) in rats to assess the subtle changes that occur during the degeneration process. PPCT provides vivid 3D images of micromorphological changes in the LFJ during its degeneration process, and the changes in the subchondral bone occurred earlier than in the cartilage during the early stage of degeneration of the LFJ. The delineation of this alteration was similar to that with the histological method. Our findings demonstrated that PPCT could serve as a valuable tool for 3D visualization of the morphology of the LFJ by providing comprehensive information about the cartilage and the underlying subchondral bone and their changes during degeneration processes. It might also have great potential for providing effective diagnostic tools to track changes in the cartilage and to evaluate the effects of therapeutic interventions for LFJ degeneration in preclinical studies.
Kenneth G Mann - One of the best experts on this subject based on the ideXlab platform.
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what is all that thrombin for
Journal of Thrombosis and Haemostasis, 2003Co-Authors: Kenneth G Mann, Kathleen E Brummel, Saulius ButenasAbstract:Summary. The hemostatic process initiated by the exposure of tissue factor to blood is a threshold limited reaction which occurs in two distinct Phases. During an initiationPhase, small amounts of factor (F)Xa, FIXa and thrombin are generated. The latter activates the procofactors FV and FVIII to the activated cofactors which together with their companion serine proteases form the intrinsic FX activator (FVIIIa-FIXa) and prothrombinase (FVa-FXa) which generate the bulk of FXa and thrombin during a Propagation Phase. The clotting process (fibrin formation) occurs at the inception of the Propagation Phase when only 5-10 nM thrombin has been produced. Consequently, the vast majority (greater than 95%) of thrombin is produced after clotting during the Propagation Phase of thrombin generation. The blood of individuals with either hemophilia A or hemophilia B has no ability to generate the intrinsic FXase, and hence is unable to support the Propagation Phase of the reaction. Since clot based assays conclude before the Propagation Phase they are not sensitive to hemophilia A and B. The inception and magnitude of the Propagation Phase of thrombin generation is influenced by genetic polymorphisms associated with thrombotic and hemorrhagic disease, by the natural abundance of pro- and anticoagulants in healthy individuals and by pharmacologic interventions which influence thrombotic pathology. Therefore, it is our suspicion that the performance of the entire process of thrombin generation from initiation through Propagation and termination Phases of the reaction are relevant with respect to both hemorrhagic and thrombotic pathology.
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thrombin functions during tissue factor induced blood coagulation
Blood, 2002Co-Authors: Kathleen E Brummel, Saulius Butenas, Sara G Paradis, Kenneth G MannAbstract:Tissue factor–induced blood coagulation was studied in 20 individuals, for varying periods of time during 54 months, in contact pathway–inhibited whole blood at 37°C and evaluated in terms of the activation of various substrates. After quenching over time with inhibitors, the soluble Phases were analyzed for thrombin–antithrombin III (TAT) complex formation, prothrombin fragments, platelet activation (osteonectin release), factor Va generation, fibrinopeptide (FP) A and FPB release, and factor XIII activation. TAT complex formation, for 35 experiments, showed an initiation Phase (up to 4.6 ± 0.6 minutes) in which thrombin was generated at an average rate of 0.93 ± 0.3 nM/min catalyzed by about 1.3 pM prothrombinase yielding approximately 26 nM thrombin. During a subsequent Propagation Phase, thrombin was generated at a rate of 83.9 ± 3.8 nM/min by about 120 pM prothrombinase, reaching ultimate levels of 851 ± 53 nM. Clot time, determined subjectively, occurred at 4.7 ± 0.2 minutes and correlated with the inception of the Propagation Phase. The thrombin concentrations associated with the transitions to rapid product formation are 510 ± 180 pM for platelet activation (1.9 ± 0.2 minutes), 840 ± 280 pM for factor XIII activation and factor Va generation (2.2 ± 0.6 minutes), 1.3 ± 0.4 nM for FPA release (2.5 ± 0.7 minutes), 1.7 ± 0.5 nM for FPB release and prethrombin 2 (2.8 ± 0.8 minutes), 7.0 ± 2.2 nM for thrombin B chain (3.6 ± 0.2 minutes), and 26 ± 6.2 nM for the Propagation Phase of TAT formation (4.6 ± 0.6 minutes). These results illustrate that the initial activation of thrombin substrates occurs during the initiation Phase at less than 2 nM thrombin (0.2%). Most thrombin (96%) is formed well after clotting occurs.
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thrombin functions during tissue factor induced blood coagulation
Blood, 2002Co-Authors: Kathleen E Brummel, Saulius Butenas, Sara G Paradis, Kenneth G MannAbstract:Tissue factor-induced blood coagulation was studied in 20 individuals, for varying periods of time during 54 months, in contact pathway-inhibited whole blood at 37 degrees C and evaluated in terms of the activation of various substrates. After quenching over time with inhibitors, the soluble Phases were analyzed for thrombin-antithrombin III (TAT) complex formation, prothrombin fragments, platelet activation (osteonectin release), factor Va generation, fibrinopeptide (FP) A and FPB release, and factor XIII activation. TAT complex formation, for 35 experiments, showed an initiation Phase (up to 4.6 +/- 0.6 minutes) in which thrombin was generated at an average rate of 0.93 +/- 0.3 nM/min catalyzed by about 1.3 pM prothrombinase yielding approximately 26 nM thrombin. During a subsequent Propagation Phase, thrombin was generated at a rate of 83.9 +/- 3.8 nM/min by about 120 pM prothrombinase, reaching ultimate levels of 851 +/- 53 nM. Clot time, determined subjectively, occurred at 4.7 +/- 0.2 minutes and correlated with the inception of the Propagation Phase. The thrombin concentrations associated with the transitions to rapid product formation are 510 +/- 180 pM for platelet activation (1.9 +/- 0.2 minutes), 840 +/- 280 pM for factor XIII activation and factor Va generation (2.2 +/- 0.6 minutes), 1.3 +/- 0.4 nM for FPA release (2.5 +/- 0.7 minutes), 1.7 +/- 0.5 nM for FPB release and prethrombin 2 (2.8 +/- 0.8 minutes), 7.0 +/- 2.2 nM for thrombin B chain (3.6 +/- 0.2 minutes), and 26 +/- 6.2 nM for the Propagation Phase of TAT formation (4.6 +/- 0.6 minutes). These results illustrate that the initial activation of thrombin substrates occurs during the initiation Phase at less than 2 nM thrombin (0.2%). Most thrombin (96%) is formed well after clotting occurs.
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blood coagulation in hemophilia a and hemophilia c
Blood, 1998Co-Authors: Kevin M Cawthern, Cornelis Van T Veer, Jennifer B Lock, Maria E Dilorenzo, Richard F Branda, Kenneth G MannAbstract:Tissue factor (TF)-induced coagulation was compared in contact pathway suppressed human blood from normal, factor VIII-deficient, and factor XI-deficient donors. The progress of the reaction was analyzed in quenched samples by immunoassay and immunoblotting for fibrinopeptide A (FPA), thrombin-antithrombin (TAT), factor V activation, and osteonectin. In hemophilia A blood (factor VIII:C <1%) treated with 25 pmol/L TF, clotting was significantly delayed versus normal, whereas replacement with recombinant factor VIII (1 U/mL) restored the clot time near normal values. Fibrinopeptide A release was slower over the course of the experiment than in normal blood or hemophilic blood with factor VIII replaced, but significant release was observed by the end of the experiment. Factor V activation was significantly impaired, with both the heavy and light chains presenting more slowly than in the normal or replacement cases. Differences in platelet activation (osteonectin release) between normal and factor VIII-deficient blood were small, with the midpoint of the profiles observed within 1 minute of each other. Thrombin generation during the Propagation Phase (subsequent to clotting) was greatly impaired in factor VIII deficiency, being depressed to less than 1/29 (<1.9 nmol TAT/L/min) the rate in normal blood (55 nmol TAT/L/min). Replacement with recombinant factor VIII normalized the rate of TAT generation. Thus, coagulation in hemophilia A blood at 25 pmol/L TF is impaired, with significantly slower thrombin generation than normal during the Propagation Phase; this reduced thrombin appears to affect FPA production and factor V activation more profoundly than platelet activation. At the same level of TF in factor XI-deficient blood (XI:C <2%), only minor differences in clotting or product formation (FPA, osteonectin, and factor Va) were observed. Using reduced levels of initiator (5 pmol/L TF), the reaction was more strongly influenced by factor XI deficiency. Clot formation was delayed from 11.1 to 15.7 minutes, which shortened to 9.7 minutes with factor XI replacement. The maximum thrombin generation rate observed (∼37 nmol TAT/L/min) was approximately one third that for normal (110 nmol/L TAT/min) or with factor XI replacement (119 nmol TAT/L/min). FPA release, factor V activation, and release of platelet osteonectin were slower in factor XI-deficient blood than in normal blood. The data demonstrate that factor XI deficiency results in significantly delayed clot formation only at sufficiently low TF concentrations. However, even at these low TF concentrations, significant thrombin is generated in the Propagation Phase after formation of the initial clot in hemophilia C blood.
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evaluation of the initiation Phase of blood coagulation using ultrasensitive assays for serine proteases
Journal of Biological Chemistry, 1997Co-Authors: Saulius Butenas, C Van T Veer, Kenneth G MannAbstract:Abstract The initiation Phase of enzyme generation in a reconstituted model of the tissue factor (TF) pathway to thrombin was evaluated. At 1.25 pm added TF, no thrombin generation was observed in the absence of factor V. The substitution of factor Va for factor V increased the rate of thrombin generation. Factor X activation during the initiation Phase was not influenced by the absence of factor VIII or thrombin, leading to the conclusion that initially factor Xa is generated exclusively by the factor VIIa-TF complex. When thrombin was eliminated from the system, no contribution of the factor IXa-factor VIIIa complex to factor X activation was observed during the Propagation Phase. Similarly, factor V activation was also not observed in the absence of thrombin, indicating that thrombin is the only enzyme responsible for factor V and factor VIII activation. Only subnanomolar amounts of factor VII were activated when prothrombin activation was almost complete. In the absence of coagulation inhibitors, factor XI did not influence thrombin generation initiated by 1.25 pm factor VIIa-TF complex. The termination of factor XIa generation by added hirudin in the factor XI experiment indicates that factor XI activation occurs exclusively by thrombin.
Bernhard Elsener - One of the best experts on this subject based on the ideXlab platform.
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corrosion rate of carbon steel in carbonated concrete a critical review
Cement and Concrete Research, 2018Co-Authors: Matteo Stefanoni, Ueli Angst, Bernhard ElsenerAbstract:Abstract Reinforced concrete with lower environmental footprint (lower CO2 emission) can be obtained by reducing the clinker content in the cements. As the carbonation of concrete is faster, corrosion of steel in carbonated concrete during the Propagation Phase is becoming important both for science and practice. The present literature review summarizes the state of the art, reporting corrosion rate data for a broad range of cement types, w/b ratios and environmental conditions. Correlations between corrosion rate and the main influencing parameters are elaborated and discussed. It confirms that the corrosion rate of steel in carbonated concrete is not under ohmic control. More important are the degree of pore saturation and the effective steel area in contact with water filled pores. It also emerges that the new blended cements have to be systematically studied with respect to the corrosion behavior of steel in carbonated concrete in order to make reliable service life prediction.
Keisuke Tanaka - One of the best experts on this subject based on the ideXlab platform.
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crack initiation life in notched steel bars under torsional fatigue synthesis based on the averaged strain energy density approach
International Journal of Fatigue, 2017Co-Authors: Alberto Campagnolo, Giovanni Meneghetti, Filippo Berto, Keisuke TanakaAbstract:Abstract In a recent contribution by Tanaka, the fatigue behaviour of notched bars made of austenitic stainless steel, SUS 316L, and carbon steel, SGV 410, characterized by different values of the notch tip radius was investigated under torsion loading. Tanaka monitored both fatigue crack initiation and Propagation Phases by means of the potential drop technique. The crack initiation life is correlated here to the depth of the initiated fatigue crack by means of calibration curves derived from electrical finite element (FE) analyses. In the present contribution, the approach based on the strain energy density (SED) averaged over a structural volume embracing the notch tip is employed to re-analyse the original experimental results of each material, by taking into account the crack initiation life, in order to exclude all extrinsic mechanisms acting during the crack Propagation Phase, i.e. sliding contact, friction and meshing between crack mating surfaces.
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crack initiation life in notched ti 6al 4v titanium bars under uniaxial and multiaxial fatigue synthesis based on the averaged strain energy density approach
Fracture and Structural Integrity, 2017Co-Authors: Giovanni Meneghetti, Alberto Campagnolo, Filippo Berto, Keisuke TanakaAbstract:The fatigue behaviour of circumferentially notched specimens made of titanium alloy, Ti-6Al-4V, has been analysed. To investigate the notch effect on the fatigue strength, pure bending, pure torsion and multiaxial bending-torsion fatigue tests have been carried out on specimens characterized by two different root radii, namely 0.1 and 4 mm. Crack nucleation and subsequent Propagation have been accurately monitored by using the direct current potential drop (DCPD) technique. Based on the results obtained from the potential drop technique, the crack initiation life has been defined in correspondence of a relative potential drop increase ?V/?V0 equal to 1%, and it has been used as failure criterion. Doing so, the effect of extrinsic mechanisms operating during crack Propagation Phase, such as sliding contact, friction and meshing between fracture surfaces, is expected to be reduced. The experimental fatigue test results have been re-analysed by using the local strain energy density (SED) averaged over a structural volume having radius R0 and surrounding the notch tip. Finally, the use of the local strain energy density parameter allowed us to properly correlate the crack initiation life of Ti-6Al-4V notched specimens, despite the different notch geometries and loading conditions involved in the tests.
