189 research outputs found

    Roles of Reactive Oxygen Species in Anticancer Therapy with Salvia miltiorrhiza Bunge

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    Cancer is a leading cause of death worldwide. We aim to provide a systematic review about the roles of reactive oxygen species (ROS) in anticancer therapy with Salvia miltiorrhiza Bunge (Danshen). Danshen, including its lipophilic and hydrophilic constituents, is potentially beneficial for treating various cancers. The mechanisms of ROS-related anticancer effects of Danshen vary depending on the specific type of cancer cells involved. Danshen may enhance TNF-α-induced apoptosis, upregulate caspase-3, caspase-8, caspase-9, endoplasmic reticulum stress, P21, P53, Bax/Bcl-2, DR5, and AMP-activated protein kinase, or activate the p38/JNK, mitogen-activated protein kinase, and FasL signaling pathways. Conversely, Danshen may downregulate human telomerase reverse transcriptase mRNA, telomerase, survivin, vascular endothelial growth factor/vascular endothelial growth factor receptor 2, CD31, NF-κB, Erk1/2, matrix metalloproteinases, microtubule assembly, and receptor tyrosine kinases including epidermal growth factor receptors, HER2, and P-glycoprotein and inhibit the PI3K/Akt/mTOR or estrogen receptor signaling pathways. Therefore, Danshen may inhibit cancer cells proliferation through antioxidation on tumor initiation and induce apoptosis or autophagy through ROS generation on tumor progression, tumor promotion, and tumor metastasis. Based on the available evidence regarding its anticancer properties, this review provides new insights for further anticancer research or clinical trials with Danshen

    Dynamical coupled-channel model of kaon-hyperon interactions

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    The pi N --> KY and KY --> KY reactions are studied using a dynamical coupled-channel model of meson-baryon interactions at energies where the baryon resonances are strongly excited. The channels included are: pi N, K \Lambda, and K\Sigma. The resonances considered are: N^* [S_{11}(1650), P_{11}(1710), P_{13}(1720),D_{13}(1700)]; \Delta^* [S_{31}(1900), P_{31}(1910), P_{33}(1920)]; \Lambda ^* [S_{01}(1670), P_{01}(1810)] \Sigma^* [P_{11}(1660), D_{13}(1670)]; and K^*(892). The basic non-resonant \pi N --> KY and KY --> KY transition potentials are derived from effective Lagrangians using a unitary transformation method. The dynamical coupled-channel equations are simplified by parametrizing the pi N -->pi N amplitudes in terms of empirical pi N partial-wave amplitudes and a phenomenological off-shell function. Two models have been constructed. Model A is built by fixing all coupling constants and resonance parameters using SU(3) symmetry, the Particle Data Group values, and results from a constituent quark model. Model B is obtained by allowing most of the parameters to vary around the values of model A in fitting the data. Good fits to the available data for pi^- p to K^0 \Lambda, K^0 \Sigma^0 have been achieved. The investigated kinematics region in the center-of-mass frame goes from threshold to 2.5 GeV. The constructed models can be imbedded into associated dynamical coupled-channel studies of kaon photo- and electro-production reactions.Comment: 35 pages, 11 Figure

    Unitary model for the γpγπ0p\gamma p \to \gamma \pi^0 p reaction and the magnetic dipole moment of the Δ+(1232)\Delta^+(1232)

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    Radiative pion photoproduction in the Δ(1232)\Delta(1232) resonance region is studied with the aim to access the Δ+(1232)\Delta^+(1232) magnetic dipole moment. We present a unitary model of the γpγπN\gamma p \to \gamma \pi N (πN=π0p,π+n\pi N = \pi^0 p, \pi^+ n) reactions, where the πN\pi N rescattering is included in an on-shell approximation. In this model, the low energy theorem which couples the γpγπN\gamma p \to \gamma \pi N process in the limit of a soft final photon to the γpπN\gamma p \to \pi N process is exactly satisfied. We study the sensitivity of the γpγπ0p\gamma p \to \gamma \pi^0 p process at higher values of the final photon energy to the Δ+(1232)\Delta^+(1232) magnetic dipole moment. We compare our results with existing data and give predictions for forthcoming measurements of angular and energy distributions. It is found that the photon asymmetry and a helicity cross section are particularly sensitive to the Δ+\Delta^+ magnetic dipole moment.Comment: 23 pages, 18 figure

    Threshold J/ψJ/\psi- production in nucleon-nucleon collisions

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    We analyze J/ψJ/\psi- production in nucleon-nucleon collisions near threshold in the framework of a general model independent formalism, which can be applied to any reaction N+NN+N+V0N+N\to N+N+V^0, where V0=ωV^0=\omega, ϕ\phi, or J/ψJ/\psi. Such reactions show large isotopic effects: a large difference for pppp- and pnpn-collisions, which is due to the different spin structure of the corresponding matrix elements. The analysis of the spin structure and of the polarization observables is based on symmetry properties of the strong interaction. Using existing experimental data on the different decays of J/ψJ/\psi-meson, we suggest a model for N+NN+N+J/ψN+N\to N+N+J/\psi, based on tt-channel η+π\eta+\pi-exchanges. We predict polarization phenomena for the n+pn+p+J/ψn+p\to n+p+J/\psi-reaction and the ratio of cross sections for npnp and pppp-collisions. For the processes η(π)+NN+J/ψ\eta(\pi)+N\to N+J/\psi we apply two different approaches: vector meson exchange and local four-particle interaction. In both cases we find larger J/ψJ/\psi-production in npnp-collisions, with respect to pppp-collisions.Comment: 17 pages, 6 figure

    An isobar model for eta photo- and electroproduction on the nucleon

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    An isobar model containing Born terms, vector meson exchange and nucleon resonances is used to analyze recent eta photoproduction data for cross section and beam asymmetry, as well as JLab electroproduction data. Good overall description is achieved up to Q^2 = 4.0 (GeV/c)^2. Besides the dominant S11(1535) resonance, we show that the second S11 resonance, S11(1650), is also necessary to be included in order to extract S11(1535) resonance parameters properly. In addition, the beam asymmetry data allow us to extract very small ( eta N decay branching ratios of D13(1520) and F15(1680) resonances because of the overwhelming s-wave dominance. The model is implemented as a part of the MAID program.Comment: 5 pages, 4 eps figures, uses ws-p8-50x6-00.cls, talk given at NSTAR2001, Workshop on The Physics of Excited Nucleons, Mainz, Germany, March 7-10, 2001, to be published in World Scientifi