189 research outputs found

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

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-Î±-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-ÎºB, 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

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 $\gamma p \to \gamma \pi^0 p$ reaction and the magnetic dipole moment of the $\Delta^+(1232)$

Radiative pion photoproduction in the $\Delta(1232)$ resonance region is
studied with the aim to access the $\Delta^+(1232)$ magnetic dipole moment. We
present a unitary model of the $\gamma p \to \gamma \pi N$ ($\pi N = \pi^0 p,
\pi^+ n$) reactions, where the $\pi N$ rescattering is included in an on-shell
approximation. In this model, the low energy theorem which couples the $\gamma
p \to \gamma \pi N$ process in the limit of a soft final photon to the $\gamma
p \to \pi N$ process is exactly satisfied. We study the sensitivity of the
$\gamma p \to \gamma \pi^0 p$ process at higher values of the final photon
energy to the $\Delta^+(1232)$ 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 $\Delta^+$ magnetic dipole
moment.Comment: 23 pages, 18 figure

### Threshold $J/\psi-$ production in nucleon-nucleon collisions

We analyze $J/\psi-$ production in nucleon-nucleon collisions near threshold
in the framework of a general model independent formalism, which can be applied
to any reaction $N+N\to N+N+V^0$, where $V^0=\omega$, $\phi$, or $J/\psi$. Such
reactions show large isotopic effects: a large difference for $pp$- and
$pn$-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
$J/\psi-$meson, we suggest a model for $N+N\to N+N+J/\psi$, based on
$t-$channel $\eta+\pi$-exchanges. We predict polarization phenomena for the
$n+p\to n+p+J/\psi$-reaction and the ratio of cross sections for $np$ and
$pp$-collisions. For the processes $\eta(\pi)+N\to N+J/\psi$ we apply two
different approaches: vector meson exchange and local four-particle
interaction. In both cases we find larger $J/\psi$-production in
$np$-collisions, with respect to $pp$-collisions.Comment: 17 pages, 6 figure

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

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

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