268 research outputs found
TRAF3 Negatively Regulates Platelet Activation and Thrombosis
CD40 ligand (CD40L), a member of the tumor necrosis factor (TNF) superfamily, binds to CD40, leading to many effects depending on target cell type. Platelets express CD40L and are a major source of soluble CD40L. CD40L has been shown to potentiate platelet activation and thrombus formation, involving both CD40-dependent and -independent mechanisms. A family of proteins called TNF receptor associated factors (TRAFs) plays key roles in mediating CD40L-CD40 signaling. Platelets express several TRAFs. It has been shown that TRAF2 plays a role in CD40L-mediated platelet activation. Here we show that platelet also express TRAF3, which plays a negative role in regulating platelet activation. Thrombin- or collagen-induced platelet aggregation and secretion are increased in TRAF3 knockout mice. The expression levels of collagen receptor GPVI and integrin αIIbβ3 in platelets were not affected by deletion of TRAF3, suggesting that increased platelet activation in the TRAF3 knockout mice was not due to increased expression platelet receptors. Time to formation of thrombi in a FeCl3-induced thrombosis model was significantly shortened in the TRAF3 knockout mice. However, mouse tail-bleeding times were not affected by deletion of TRAF3. Thus, TRAF3 plays a negative role in platelet activation and in thrombus formation in vivo
High Reversibility of Lattice Oxygen Redox in Na-ion and Li-ion Batteries Quantified by Direct Bulk Probes of both Anionic and Cationic Redox Reactions
The reversibility and cyclability of anionic redox in battery electrodes hold
the key to its practical employments. Here, through mapping of resonant
inelastic X-ray scattering (mRIXS), we have independently quantified the
evolving redox states of both cations and anions in Na2/3Mg1/3Mn2/3O2. The
bulk-Mn redox emerges from initial discharge and is quantified by
inverse-partial fluorescence yield (iPFY) from Mn-L mRIXS. Bulk and surface Mn
activities likely lead to the voltage fade. O-K super-partial fluorescence
yield (sPFY) analysis of mRIXS shows 79% lattice oxygen-redox reversibility
during initial cycle, with 87% capacity sustained after 100 cycles. In
Li1.17Ni0.21Co0.08Mn0.54O2, lattice-oxygen redox is 76% initial-cycle
reversible but with only 44% capacity retention after 500 cycles. These results
unambiguously show the high reversibility of lattice-oxygen redox in both
Li-ion and Na-ion systems. The contrast between Na2/3Mg1/3Mn2/3O2 and
Li1.17Ni0.21Co0.08Mn0.54O2 systems suggests the importance of distinguishing
lattice-oxygen redox from other oxygen activities for clarifying its intrinsic
properties.Comment: 33 pages, 8 Figures. Plus 14 pages of Supplementary Materials with 12
Figure
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