The pyrophoric character of zerovalent iron nanoparticles and cumbersome handling of this material has been a drawback in practical applications, despite the expectation of an enhanced reactivity. We have been interested in how the iron nanoparticles can gain stability in air without significantly sacrificing reactivity. The freshly synthesized iron nanoparticles ignited spontaneously upon exposure to air. However, when exposed slowly to air, an approximately 5 nm coating of iron oxide was formed on the surface of particles. The oxide shell did not thicken for at least two months, indicating no sign of further corrosion of iron particles. The reactivity studies on nitrate reduction showed that the freshly synthesized iron reacted at the fastest rate. After formation of the oxide shell the rate constants decreased by ca. 50% of that of fresh iron, but were still higher than that of commercial grade micro- or milli-sized iron powder. Nitrate (50 ppm/350 mL) can be recharged 6 times into a bottle containing 0.5 g of iron nanoparticles. The reduction rate of the second cycle was the fastest among the six cycles, which can be attributed to the increase of surface area and the fresh iron surfaces that were bared by the dissolution of oxidized iron species on the surface. The oxidized iron was transformed to crystalline magnetite (Fe3O4) in solution.

Given a previous report that Bcl-w is expressed in gastric cancer cells, particularly in those of an infiltrative morphology, we investigated whether Bcl-w expression influences the invasiveness of gastric cancer cells. To accomplish this, Bcl-w was overexpressed in adherent types of gastric adenocarcinoma cell lines, and this was found to result in an increase in their migratory and invasive potentials. These effects were not induced when Bcl-2 was overexpressed in the same cell types. Consistently, Bcl-w, but not Bcl-2, overexpression increased matrix metalloproteinase-2 (MMP-2) expression, and synthetic or natural inhibitors of MMP-2 abolished Bcl-w-induced cell invasion. Bcl-w overexpression also activated phosphoinositide 3-kinase (PI3K), Akt, and Sp1, and the blocking effects of each of these components using pharmacologic inhibitors, dominant-negative mutants, or small interfering RNA abolished the ability of Bcl-w to induce MMP-2 and cell invasion. The inhibition of PI3K/Akt signaling also prevented Sp1 activation. Overall, our data suggest that Bcl-w, which was previously shown to enhance gastric cancer cell survivability, also promotes their invasiveness by inducing MMP-2 expression via the sequential actions of PI3K, Akt, and Sp1. (Cancer Res 2006; 66(10): 4991-5)

Escherichia coli SdiA is a quorum-sensing (QS) receptor that responds to autoinducers produced by other bacterial species to control cell division and virulence. Crystal structures reveal that E. coli SdiA, which is composed of an N-terminal ligand-binding domain and a C-terminal DNA-binding domain (DBD), forms a symmetrical dimer. Although each domain shows structural similarity to other QS receptors, SdiA differs from them in the relative orientation of the two domains, suggesting that its ligand-binding and DNA-binding functions are independent. Consistently, in DNA gel-shift assays the binding affinity of SdiA for the ftsQP2 promoter appeared to be insensitive to the presence of autoinducers. These results suggest that autoinducers increase the functionality of SdiA by enhancing the protein stability rather than by directly affecting the DNA-binding affinity. Structural analyses of the ligand-binding pocket showed that SdiA cannot accommodate ligands with long acyl chains, which was corroborated by isothermal titration calorimetry and thermal stability analyses. The formation of an intersubunit disulfide bond that might be relevant to modulation of the DNA-binding activity was predicted from the proximal position of two Cys residues in the DBDs of dimeric SdiA. It was confirmed that the binding affinity of SdiA for the uvrY promoter was reduced under oxidizing conditions, which suggested the possibility of regulation of SdiA by multiple independent signals such as quorum-sensing inducers and the oxidation state of the cell.

Chronic cerebral hypoperfusion is associated with vascular dementia (VaD).Cerebral hypoperfusion may initiate complex molecular and cellular inflammatory pathways that contribute to long-term cognitive impairment and memory loss. Here we used a bilateral common carotid artery stenosis (BCAS) mouse model of VaD to investigate its effect on the innate immune response -particularly the inflammasome signaling pathway. Comprehensive analyses revealed that chronic cerebral hypoperfusion induces a complex temporal expression and activation of inflammasome components and their downstream products (IL-1β and IL-18) in different brain regions, and promotes activation of apoptotic and pyroptotic cell death pathways. Polarized glial cell activation, white matter lesion formation and hippocampal neuronal loss also occurred in a spatiotemporal manner. Moreover, in AIM2 knockout mice we observed attenuated inflammasome-mediated production of proinflammatory cytokines, apoptosis and pyroptosis, as well as resistance to chronic microglial activation, myelin breakdown, hippocampal neuronal loss, and behavioural and cognitive deficits following BCAS. Hence, we have demonstrated that activation of the AIM2 inflammasome substantially contributes to the pathophysiology of chronic cerebral hypoperfusion-induced brain injury and may therefore represent a promising therapeutic target for attenuating cognitive impairment in VaD. 9 used as a loading control. *P<0.05 compared with Sham. (b), representative 9 immunofluorescence analysis of Iba-1 and GFAP in the cerebral cortex provide 9 supporting evidence of microglial activation following BCAS. Magnification x 100. 9 Scale bar, 20μm. Images were taken under identical exposures and conditions. (c), 9 representative immunoblots and quantification illustrating increased astroglia 9 activation due to increased levels of GFAP in the hippocampus over time following 9 BCAS. Data are represented as mean ± S.E.M. n=6-7 mice in each experimental 9

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The DNA-dependent activator of IFN-regulatory factors (DAI), also known as DLM-1/ZBP1, initiates an innate immune response by binding to foreign DNAs in the cytosol. For full activation of the immune response, three DNA binding domains at the N terminus are required: two Z-DNA binding domains (ZBDs), Zα and Zβ, and an adjacent putative B-DNA binding domain. The crystal structure of the Zβ domain of human DAI (hZβ DAI ) in complex with Z-DNA revealed structural features distinct from other known Z-DNA binding proteins, and it was classified as a group II ZBD. To gain structural insights into the DNA binding mechanism of hZβ DAI , the solution structure of the free hZβ DAI was solved, and its bindings to B-and Z-DNAs were analyzed by NMR spectroscopy. Compared to the Z-DNA-bound structure, the conformation of free hZβ DAI has notable alterations in the α3 recognition helix, the "wing," and Y145, which are critical in Z-DNA recognition. Unlike some other Zα domains, hZβ DAI appears to have conformational flexibility, and structural adaptation is required for Z-DNA binding. Chemical-shift perturbation experiments revealed that hZβ DAI also binds weakly to B-DNA via a different binding mode. The C-terminal domain of DAI is reported to undergo a conformational change on B-DNA binding; thus, it is possible that these changes are correlated. During the innate immune response, hZβ DAI is likely to play an active role in binding to DNAs in both B and Z conformations in the recognition of foreign DNAs. DNA can activate immune responses in the innate immune system. Nonmethylated CpG sequences are recognized by toll-like receptor 9, and this results in inducing type-I interferon (IFN) (1). Double-stranded DNA, when placed in the cytosol of a cell by invading microbes or left by incomplete clearance of DNA damage, also can evoke immune responses (2-4). A recent study demonstrated that, in addition, the DNA-dependent activator of IFN-regulatory factors (DAI), formerly known as DLM-1 or ZBP1, also detects cytosolic DNAs and activates the innate immune response (5). DAI mediates activation of the innate immune system by facilitating DNA-mediated induction of type-I IFN and the expression of other related genes. DAI contains three DNA binding domains in the N terminus: two Z-DNA binding domains (ZBDs), Zα and Zβ, and an adjacent D3 region, a putative B-DNA binding domain. The D3 region plays pivotal roles in DNA binding, but all three domains are indispensable for the full activation of DAI (6). An intriguing question in innate immunity is how diverse foreign DNAs in the B-or Z-DNA conformations can be efficiently recognized by the DNA binding domains of DAI.For the last decade there have been extensive structural and biochemical studies on ZBDs. The editing enzyme ADAR1 (double-stranded RNA adenosine deaminase) was the first Zα-containing protein to be identified. Zα domains were also found in the vaccinia virus E3L protein (7) and in PKZ (protein kinase containing Z-DNA binding domain). Crystal structures of the Zα domains of A...

Chronic kidney disease (CKD) is a common cause of end-stage renal disease. Antihypertensive agents are used clinically to inhibit the progression of CKD, but cannot prevent eventual renal failure. This study investigated the effect of Tanshinone IIA, an active component of Salvia miltiorrhiza, in rats suffering from CKD induced by 5/6 nephrectomy. After development of renal insufficiency, the rats were treated with Tanshinone IIA (10 mg/kg) for 8 weeks. Serum creatinine, angiotensin II (Ang II), transforming growth factor β1 (TGF-β1) and collagen IV levels were significantly reduced in Tanshinone IIA treated rats compared with a control group. In addition, Tanshinone IIA suppressed increases in urinary protein excretion in CKD rats. These findings suggest that chronic oral administration of Tanshinone IIA can improve renal dysfunction associated with CKD.

Abstract. In the present study, we investigated the neuroprotective effect of Korean red ginseng (KRG) following focal brain ischemia/reperfusion injury, in relation to its antioxidant activities. The middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats was employed. The KRG extract (100 mg/kg, perorally) was administered once daily for 7 days following MCAO/R. The elevated levels of lipid peroxidation in the MCAO/R group were attenuated significantly in the KRG-administered group. The significantly depleted activity of the antioxidant enzymes glutathione peroxidase, superoxide dismutase and catalase was prevented in the KRG-administered group. In the neurobehavioral evaluation expressed as the modified neurological severity score and corner-turn test, the daily intake of KRG showed consistent and significant improvement in the neurological deficits for 7 days following MCAO/R injury. These results indicate that KRG has a neuroprotective effect against ischemia/reperfusion brain injury by reducing the level of lipid peroxidation and increasing the endogenous antioxidant enzymatic activity.