Search

Two-photon absorption spectra and two-photon absorption cross sections of Cl-substituted diphenylacetylenes (ClDPAs) were investigated by optical-probing photoacoustic spectroscopy and quantum chemical calculations for the first time. The two-photon absorption spectra of ClDPAs exhibited intense two-photon absorption bands at around 480 nm, which are forbidden by one-photon absorption. The two-photon absorption cross sections σ(2) of o-, m-, and p-ClDPAs at 476 nm were determined to be 22 ± 1, 23 ± 1, and 38 ± 2 GM, respectively. Compared with diphenylacetylene (DPA) (27 GM at 472 nm), the σ(2) values of o- and m-ClDPAs were lower, while that of p-ClDPA was higher. Simulated two-photon absorption spectra using the TD-B3LYP/6-311+G(d,p) level of calculations within the Tamm-Dancoff approximation, based on the three-state model, well agreed with the experimental results. The difference in the σ(2) values of DPA and ClDPAs was responsible for those in the transition dipole moments between the intermediate and the final states. [ABSTRACT FROM AUTHOR]

Post-ischemic inflammation is an essential step in the progression of brain ischemia-reperfusion injury. However, the mechanism that activates infiltrating macrophages in the ischemic brain remains to be clarified. Here we demonstrate that peroxiredoxin (Prx) family proteins released extracellularly from necrotic brain cells induce expression of inflammatory cytokines including interleukin-23 in macrophages through activation of Toll-like receptor 2 (TLR2) and TLR4, thereby promoting neural cell death, even though intracellular Prxs have been shown to be neuroprotective. The extracellular release of Prxs in the ischemic core occurred 12 h after stroke onset, and neutralization of extracellular Prxs with antibodies suppressed inflammatory cytokine expression and infarct volume growth. In contrast, high mobility group box 1 (HMGB1), a well-known damage-associated molecular pattern molecule, was released before Prx and had a limited role in post-ischemic macrophage activation. We thus propose that extracellular Prxs are previously unknown danger signals in the ischemic brain and that its blocking agents are potent neuroprotective tools., Stroke is one of the major causes of death and disability worldwide. The only globally approved treatment for ischemic stroke is tissue plasminogen activator, a time-dependent therapy that must be [...]

Sugimoto H, Okada K, Shoda J, Warabi E, Ishige K, Ueda T, Taguchi K, Yanagawa T, Nakahara A, Hyodo I, Ishii T, Yamamoto M. Deletion of nuclear factor-E2-related factor-2 leads to rapid onset and progression of nutritional steatohepatitis in mice. Am J Physiol Gastrointest Liver Physiol 298: G283-G294, 2010. First published November 19, 2009; doi: 10.1152/ajpgi.00296.2009.--Oxidative stress is a critical mediator in liver injury of steatohepatitis. The transcription factor Nrf2 serves as a cellular stress sensor and is a key regulator for induction of hepatic detoxification and antioxidarive stress systems. The involvement of Nrf2 in defense against the development of steatohepatitis remains unknown. We aimed to investigate the protective roles of Nrf2 in nutritional steatohepatitis using wild-type (WT) and Nrf2 gene-null (Nrf2-null) mice. WT and Nrf2null mice were fed a methionine- and choline-deficient (MCD) diet for 3 and 6 wk, and the liver tissues were analyzed for pathology and for expression levels of detoxifying enzymes and antioxidative stress genes via the Nrf2 transcriptional pathway. In WT mice fed an MCD diet, Nrf2 was potently activated in the livers, and steatohepatitis did not develop over the observation periods. However, in Nrf2-null mice fed an MCD diet, the pathological state of the steatohepatitis was aggravated in terms of fatty changes, inflammation, fibrosis, and iron accumulation. In the livers of the Nrf2-null mice, oxidative stress was significantly increased compared with that of WT mice based on the increased levels of 4-hydroxy-2-nonenal and malondialdehyde. This change was associated with the decreased levels of glutathione, detoxifying enzymes, catalase, and superoxide dismutase activity. Correlating well with the liver pathology, the mRNA levels of factors involved in fatty acid metabolism, inflammatory cytokines, and fibrogenesis-related genes were significantly increased in the livers of the Nrf2-null mice. These findings demonstrate that Nrf2 deletion in mice leads to rapid onset and progression of nutritional steatohepatitis induced by an MCD diet. Activation of Nrf2 could be a promising target toward developing new options for prevention and treatment of steatohepatitis. Nrf2 gene-knockout mouse; transcription factor; methionine- and choline-deficient diet; oxidative stress; glutathione doi: 10.1152/ajpgi.00296.2009

Ashwagandha is an Ayurvedic shrub that forms a common ingredient of health supplements, tonics, and Indian home remedies designed to promote health and quality of life. Though sustained through experience and history, there are only a limited laboratory studies and experimental evidence to its effects. In our efforts to characterize Ashwagandha activities and their molecular mechanisms, we initially prepared leaf extract of Ashwagandha (i-Extract) that showed tumor-inhibitory activity. In the present study, we demonstrate that a major component of i-Extract and withanone (i-Factor) protected the normal human fibroblasts against the toxicity caused by withaferin A. It increased the in vitro division potential of normal human cells that appeared to be mediated by decreased accumulation of molecular damage, downregulation of the senescence-specific [beta]-galactosidase activity and the senescence marker protein, [p21.sup.WAF-1], protection against oxidative damage, and induction of proteasomal activity. To the best of our knowledge, we provide the first example of phytochemical(s) (i-Extract and withanone) that have both anticancer and antiaging activities and point to the molecular link between aging and cancer. Key Words: Ashwagandha--Extract--Human fibroblasts--Oxidative damage--Proteasomal activity--Senescence.

The protective action of ursodeoxycholic acid (UDCA) in cholestatic liver diseases may be mediated by choleresis, detoxification, and cytoprotection against oxidative stress. Nrf2, one transcription factor, serves as a cellular stress sensor and is a key regulator for hepatic induction of detoxifying enzymes, antioxidative stress genes, and numerous Mrp family members. We aimed to investigate whether UDCA induces hepatic Mrp expression along with that of detoxifying enzymes and antioxidative stress genes via the Nrf2 transcriptional pathway. The protein level, subcellular localization, and mRNA level of Mrp family members were assessed in livers of Keap1 gene-knockdown (Keap1-kd) mice and those of UDCA-fed wild-type (WT) and Nrf2 gene-null (Nrf2-null) mice. Nuclear levels of Nrf2 in livers of Keap1-kd mice markedly increased, resulting in constitutive activation of Nrf2. Keap1-kd mice have high-level expression of hepatic Mrp2, Mrp3, and Mrp4 relative to WT mice. UDCA potently increased nuclear Nrf2 expression level in livers of WT mice, and the treatment showed maximal hepatic induction of Mrp2, Mrp3, and Mrp4 in association with enhanced membranous localizations in an Nrf2-dependent manner. UDCA similarly increased nuclear Nrf2 expression level in rat hepatocytes. Chromatin immunoprecipitation assays using mouse hepatocytes revealed the binding of Nrf2 to antioxidant response elements in the promoter regions of Mrp2, Mrp3, and Mrp4. These findings demonstrate an important role of Nrf2 in the induction of Mrp family members in livers and suggest that a therapeutic mechanism of UDCA action is, via Nrf2 activation, a stimulation of detoxification and antioxidative stress systems, along with Mrp-mediated efflux transport. multidrug resistance-associated proteins; Keap1 gene-knockdown mouse; Nrf2 gene-knockout mouse; transcription factor; bile acid

Inchinkoto (ICKT), a herbal medicine, has been recognized in Japan and China as a 'magic bullet' for jaundice. To explore potent therapeutic agents for cholestasis, the effects of ICKT or its ingredients on multidrug resistance-associated protein 2 (Mrp2/MRP2)-mediated choleretic activity, as well as on antioxidative action, were investigated using rats and chimeric mice with livers that were almost completely repopulated with human hepatocytes. Biliary excretion of Mrp2 substrates and the protein mass, subcellular localization, and mRNA level of Mrp2 were assessed in rats after 1-wk oral administration of ICKT or genipin, a major ingredient of ICKT. Administration of ICKT or genipin to rats for 7 days increased bile flow and biliary excretion of bilirubin conjugates. Mrp2 protein and mRNA levels and Mrp2 membrane densities in the bile canaliculi and renal proximal tubules were significantly increased in ICKT- or genipin-treated rat livers and kidneys. ICKT and genipin, thereby, accelerated the disposal of intravenously infused bilirubin. The treatment also increased hepatic levels of heme oxygenase-1 and GSH by a nuclear factor-E2-related factor (Nrf2)-dependent mechanism. Similar effects of ICKT on MRP2 expression levels were observed in humanized livers of chimeric mice. In conclusion, these findings provide the rationale for therapeutic options of ICKT and its ingredients that should potentiate bilirubin disposal in vivo by enhancing Mrp2/MRP2-mediated secretory capacities in both livers and kidneys as well as Nrf2-mediated antioxidative actions in the treatment of cholestatic liver diseases associated with jaundice. multidrug resistance-associated proteins; bilirubin; gluthatione; heme oxygenase-1; chimeric mice with humanized liver; nuclear factor-E2-related factor doi:10.1152/ajpgi.00302.2006

DNA demethylating agents are used to reverse epigenetic silencing of tumor suppressors in cancer therapeutics. Understanding of the molecular and cellular factors involved in DNA demethylation-induced gene desilencing and senescence is still limited. We have tested the involvement of two stress chaperones, Pexl9p and mortalin, in 5-Aza-2' deoxycytidine (5AZA-dC; DNA demethylating agent)-induced senescence. We found that the cells overexpressing these chaperones were highly sensitive to 5AZA-dC, and their partial silencing eliminated 5AZA-dC-induced senescence in human osteosarcoma cells. We demonstrate that these chaperones modulate the demethylation and chromatin remodeling-dependent (as accessed by p[16.sup.INK4A] expression) and remodeling-independent (such as activation of tumor suppressor p53 pathway) senescence response of cells. Furthermore, we found the direct interactions of 5AZA-dC with these chaperones that may alter their functions. We conclude that both mortalin and Pexl9p are important mediators, prognostic indicators, and tailoring tools for 5AZA-dC-induced senescence in cancer cells.

The c-Abl and Atm are linked in the reaction of cell to DNA-damage and oxidative stress and the molecular system, which systemizes the oxidative stress response, is quite opaque. The manner in which the absence of c-Abl and Atm distinctly modifies the response of the cells to the oxidative stress by introducing the antioxidant protein, which needs the protein kinase C Delta vigorously, is discussed.

Keap1, a newly identified protein, represses nuclear activation of antioxidant-responsive elements by binding to an amino-terminal domain. Transcription factor Nrf2 is required for the antioxidant responsive element (ARE)-mediated induction of phase II oxidative and detoxifying stress enzyme genes. A new protein has been identified as result of deailed analysis of differential Nrf2 activity seen in transfected cell lines. The protein is called Keap1 and it suppresses Nrf2 transcriptional activity by binding specifically to its evolutionarily conserved amino-terminal regulatory domain. The closest homolog is a Drosophila actin-binding protein. Keap1 may be an Nrf2 cytoplasmic effector. Electrophilic agents antagonize Deap1 inhibition of Nrf2 activity in vivo. Nrf2 can go from the cytoplasm to the nucleus to potentiate ARE response. It seems Keap1 and Nrf2 make up a vital cellular sensor for oxidative stress and mediate a vital step in the signaling pathway leading to transcriptional activation.

While the reaction 22Ne(α,n)25Mg is considered an important neutron source for the s process in massive stars, the competing 22Ne(α,γ)26Mg reaction may be of considerable strength and could significantly suppress the neutron production. For a better understanding of this neutron source, the branching ratio of n and γ partial widths (Γn, Γγ) and spectroscopic information such as energies and spins of 26Mg resonance states within the Gamow window (Eα = 400-1000 keV) should be experimentally determined with improved accuracy. In the present work, we propose to use the 6Li(22Ne, 26Mg)d α-transfer reaction to investigate those resonance parameters and have tested the feasibility of the experiment.