Biomedical subjects

Xiao-Gang Wang

Publications and source records attributed to Xiao-Gang Wang.

8 recordsLinked to original sources

PubMed2006

[Immunotherapeutic effects of beta-elemene combined with interleukin-23 gene-modified dendritic cells on murine pancreatic carcinoma].

BACKGROUND & OBJECTIVE: Dendritic cell (DC) vaccine is a kind of treatment vaccine with clinical application potency. Functional cytokines can enhance anti-tumor immune response of dendritic cells. This study was to investigate the protective effects on murine pancreatic carcinoma by beta-elemene combined with bone marrow-derived dendritic cells (BM-DCs) modified with murine interleukin (IL)-23 gene. METHODS: The murine IL-23 cDNA was sub-cloned into dual-expression vector. DCs were pulsed with tumor cell lysate after modified by IL-23 gene. Mice were injected with IL-23-transfected DC vaccine, non-transfected DC vaccine, and sodium, respectively. The immune preventative and immunotherapeutic effects of DC vaccines on mice and the cytokine release in vivo were assessed. Effects of vaccine combined with beta-elemene on tumor growth and survival period of the mice were observed. RESULTS: IL-23 protein apparently increased the antigen-presenting ability of DCs. After the vaccination of DC vaccines, IFN-gamma production in treatment group was significantly more than that of the control group (P<0.01), as well as, IL-4 production was less than that in the normal group (P<0.05). Tumor growth was obviously inhibited and the survival period of the mice was obviously prolonged in beta-elemene combined with DC vaccine group than in DC, beta-elemene, or control group (P<0.01). CONCLUSIONS: IL-23-modified DC vaccines can enhance specific Th1-type and CTL response against pancreatic carcinoma cells, induce not only preventative immunity, but also auto-immunity against pancreatic carcinoma. Moreover, beta-elemene has great collaborative anti-tumor function.

Animals↗

PubMed2005

Improving the calculation of rovibrational spectra of five-atom molecules with three identical atoms by using a C3upsilonG6 symmetry-adapted grid: applied to CH3D and CHD3.

In this paper we report two improvements on the approach we have used to compute rovibrational levels of methane and apply the new ideas to calculate rovibrational levels of two methane isotopomers CH3D and CHD3. Both improvements make the bend calculation better. The first improvement is a G6-invariant (or C3upsilon-invariant) grid which is designed such that each point on the grid is mapped to another point on the grid by any of the G6 operations. The second improvement is the use of fast Fourier transform (FFT) to compute the bend potential matrix-vector products. The FFT matrix-vector product is about three and ten times faster than the previous sequential summation method for the J=0 and J>0 cases, respectively. The calculated J=1 rovibrational levels of CH3D and CHD3 on the Schwenke and Partridge [Spectrochim. Acta, Part A 57, 887 (2001)] ab initio potential are in good agreement (within 6 cm(-1) for the levels up to 3000 cm(-1)) with the experimental data. The agreement is even better (within 0.1 cm(-1) for the levels up to 6000 cm(-1)) if the associated J=0 energies are subtracted.

Journal Article↗

PubMed2005

Si/Cu interface structure and adhesion.

An ab initio investigation of the Si(111)/Cu(111) interfacial atomic structure and adhesion is reported. Misfit dislocations appear naturally, as do hcp interfacial silicide phases that vary with temperature. The silicides form in the interface even at relatively low temperatures. These results are consistent with available experimental data.

Journal Article↗

PubMed2005

Theoretical and experimental studies of the infrared rovibrational spectrum of He2-N2O.

Rovibrational spectra of the He(2)-N(2)O complex in the nu(1) fundamental band of N(2)O (2224 cm(-1)) have been observed using a tunable infrared laser to probe a pulsed supersonic jet expansion, and calculated using five coordinates that specify the positions of the He atoms with respect to the NNO molecule, a product basis, and a Lanczos eigensolver. Vibrational dynamics of the complex are dominated by the torsional motion of the two He atoms on a ring encircling the N(2)O molecule. The resulting torsional states could be readily identified, and they are relatively uncoupled to other He motions up to at least upsilon(t) = 7. Good agreement between experiment and theory was obtained with only one adjustable parameter, the band origin. The calculated results were crucial in assigning many weaker observed transitions because the effective rotational constants depend strongly on the torsional state. The observed spectra had effective temperatures around 0.7 K and involved transitions with J < or =3, with upsilon(t) = 0 and 1, and (with one possible exception) with Deltaupsilon(t)=0. Mixing of the torsion-rotation states is small but significant: some transitions with Deltaupsilon(t) not equal 0 were predicted to have appreciable intensity even assuming that the dipole transition moment coincides perfectly with the NNO axis. One such transition was tentatively assigned in the observed spectra, but confirmation will require further work.

Journal Article↗

PubMed2005

[Changes of fibronectin and type IV collagen expression in cultured rat mesangial cells transfected with Smad 2 vector].

OBJECTIVE: To study the changes of fibronectin (FN) and type IV collagen (ColIV) expression in cultured rat mesangial cells (MsC) transfected with Smad 2 vector and to investigate the molecular mechanism of glomerular extracellular matrix accumulation in glomerulosclerosis via transforming growth factor-beta (TGF-beta)/Smad signal pathway. METHODS: Smad 2 vector was transfected into MsC by calcium phosphate. Western blot analysis was used to detect Smad 2 protein. The expression of FN and ColIV proteins and their mRNAs was determined by Western blot and reverse transcriptase-polymerase chain reaction respectively. RESULTS: Four MsC clones (T-12, T-31, T-35, T-40) with Smad 2 overexpression were established. The expression of FN and ColIV was significantly increased at mRNA and protein levels in two (T-12, T-31). Compared with controls, the expression of FN proteins and mRNAs in these two clones was 2.4 times (P < 0.05) and 2.7 times (P < 0.05) higher respectively. The expression of ColIV proteins and mRNAs was 2.9 times (P < 0.01) and 3.3 times (P < 0.01) higher respectively. CONCLUSIONS: It is postulated that Smad 2 in TGF-beta/Smad signal pathway is important in promoting the accumulation of FN and ColIV in sclerotic glomeruli of diseased kidneys.

Animals↗

PubMed2004

Contracted basis Lanczos methods for computing numerically exact rovibrational levels of methane.

We present a numerically exact calculation of rovibrational levels of a five-atom molecule. Two contracted basis Lanczos strategies are proposed. The first and preferred strategy is a two-stage contraction. Products of eigenfunctions of a four-dimensional (4D) stretch problem and eigenfunctions of 5D bend-rotation problems, one for each K, are used as basis functions for computing eigenfunctions and eigenvalues (for each K) of the Hamiltonian without the Coriolis coupling term, denoted H0. Finally, energy levels of the full Hamiltonian are calculated in a basis of the eigenfunctions of H0. The second strategy is a one-stage contraction in which energy levels of the full Hamiltonian are computed in the product contracted basis (without first computing eigenfunctions of H0). The two-stage contraction strategy, albeit more complicated, has the crucial advantage that it is trivial to parallelize the calculation so that the CPU and memory costs are independent of J. For the one-stage contraction strategy the CPU and memory costs of the difficult part of the calculation scale linearly with J. We use the polar coordinates associated with orthogonal Radau vectors and spherical harmonic type rovibrational basis functions. A parity-adapted rovibrational basis suitable for a five-atom molecule is proposed and employed to obtain bend-rotation eigenfunctions in the first step of both contraction methods. The effectiveness of the two methods is demonstrated by calculating a large number of converged J = 1 rovibrational levels of methane using a global potential energy surface.

Journal Article↗

PubMed2002

Fundamental influence of C on adhesion of the Al2O3/Al interface.

Our first-principles computations indicate that the clean Al2O3/Al interface is relatively weak-weaker than bulk Al. Fracture experiments reveal that the interface is relatively strong with observed failure in bulk Al, however. This paradox is resolved via doping effects of the common impurity C. We have found that only 1/3 of a monolayer of carbon segregated to the interface can increase the work of separation by a factor of 3. The resulting strong interface is consistent with fracture experiments. It arises due to void formation in the interface, which provides low-strain sites for the carbon to segregate to. The degree of void formation is consistent with the relatively high heat of oxide formation of Al.

Journal Article↗

PubMed2002

A perturbative calculation of the rovibrational energy levels of methane.

The rovibrational energy levels of methane are determined from a quartic ab initio potential energy force field where the expansion coordinates are the Morse coordinates for the stretches and extension coordinates for the bends. Energies are calculated using canonical Van Vleck perturbation theory. Results are obtained for both rotation-vibration Hamiltonians expressed as functions of curvilinear and rectilinear normal coordinates. Second, fourth, and sixth order curvilinear results are compared with experimental results, and fourth order results for the rectilinear and curvilinear Hamiltonian are compared to each other. The calculated rovibrational levels are in good agreement with the experimental values for low J levels. The calculated rotational level splittings are in even better agreement with the experiment. In particular, the ground state tetrahedral splittings, which are as small as 10(-4) cm(-1), are well reproduced by our calculations at sixth order.

Chemical Phenomena↗