Biomedical subjects

Pengfei Shi

Publications and source records attributed to Pengfei Shi.

10 recordsLinked to original sources

PubMed2006

DNA binding properties of novel cytotoxic gold(III) complexes of terpyridine ligands: the impact of steric and electrostatic effects.

Four gold(III) complexes of terpyridine derivatives 1-4 have been synthesized and characterized by spectroscopic methods. In vitro data demonstrated that all of them showed higher cytotoxicity than cisplatin against the human non-small-cell lung cancer cell line (A-549), the human stomach carcinoma cell line (SGC-7901), the human cervix carcinoma cell line (HELA), the human colon carcinoma cell line (HCT-116), the human liver carcinoma cell line (BEL-7402), the murine leukemia cell line (P-388) and the human acute promyelocytic leukemia cell line (HL-60). Complex 3 exhibits the highest activity, with growth inhibition rates of over 80% at 10(-8) mol L(-1) against the A-549, HCT-116 and HELA tumor cell lines. Interestingly, ligands L1-L4 are also very cytotoxic against the cell lines tested. Complexes 1-4 are stable in aqueous solution for 2 days in the presence of the biological reducing agent glutathione. The inductively coupled plasma mass spectrometry data showed that DNA isolated from cells treated with complexes 1 and 3 contained gold with gold-to-nucleotide ratios of approximately 1:6,400 and 1:4,900, respectively. Fluorescence titration, UV and circular dichroism analyses proved that the steric and electrostatic effects of the ligand remarkably influence the interactions of their gold(III) complexes with DNA. The DNA binding ability of the complexes has been correlated with their cytotoxicity, which could potentially provide a new rationale for the future design of terpyridine-based metal complexes with antitumor potential.

Cell Line, Tumor↗

PubMed2006

A positively charged trinuclear 3N-chelated monofunctional platinum complex with high DNA affinity and potent cytotoxicity.

A trinuclear 3N-chelated monofunctional platinum complex, [Pt3(HPTAB)Cl3](ClO4)3 (HPTAB = N,N,N',N',N'',N''-hexakis(2-pyridylmethyl)-1,3,5-tris(aminomethyl)benzene), has been structurally characterized, which binds to DNA and demonstrates much higher potency against the murine leukemia cell line (P-388) and the human nonsmall-cell lung cancer cell line (A-549) than cisplatin.

Cell Line, Tumor↗

PubMed2006

Gold(III) compounds of 1,4,7-triazacyclononane showing high cytotoxicity against A-549 and HCT-116 tumor cell lines.

Two gold(III) compounds [Au(TACN)Cl(2)]Cl (1) and [Au(TACN)Cl(2)][AuCl(4)] (2) (where TACN=1,4,7-triazacyclononane), have been synthesized and characterized by electrospray ionization mass spectrometry (ESI-MS), (1)H NMR spectroscopy and elemental analyses. The structure of compound 2 was determined by X-ray crystallography, in which TACN coordinates to the gold(III) center in a bidentate mode and the unbound amine group forms a very short intramolecular Au-H(-N) contact (1.91A). Biological activity data showed that compound 1 is more cytotoxic than cisplatin against A-549 and HCT-116 tumor cell lines. The interactions of compound 1 with CT-DNA were studied by UV-Vis, fluorescence and CD spectroscopy, which suggests that compound 1 can induce the distortion of DNA double helix.

Antineoplastic Agents↗

PubMed2006

Ultrasonic liver discrimination using 2-D phase congruency.

In this paper, we present an experiment to extract liver features using two-dimensional phase congruency, which is invariant to changes in intensity or contrast, to try to avoid the influence of machine settings. The effectiveness of our method was tested on three classes of liver images and shows the potential for physicians to quantify liver pathology in clinical diagnosis.

Adult↗

PubMed2004

[Study on the distributed integration of the HIS and PACS based on CORBA].

In medical clinical practice, physicians need to acquire the image and text information of the patient. All the information will be of benefit for physicians to diagnose disease, improve clinical treatment, and do research work. But the information is distributed in different systems, such as medical image information in PACS (Picture Archiving and Communication System) and text records in HIS (Hospital Information System). Today many hospitals are suffering from lack of an integrated system with PACS and HIS. This paper compares PACS with HIS and puts forward a distributed integration method of integrating the PACS and HIS with the prevailing WWW technology. In such a method, the image and the text information are regarded as the common object and the operation whereon as the object operation. Thus the method integrates the PACS with HIS effectively and implements the information resources sharing with the use of web technology.

Computer Communication Networks↗

PubMed2002

Studies on the two-photon pumped upconverted fluorescence and superradiance of a new organic dye material in solutions.

The linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-ethyl-N-ethylamino)-styryl]-N-methyl-pyridinium tris(thiocyanato) cadmates (II), are reported in this paper. When pumped with a picosecond laser at the wavelength range of 850-1200 nm, intense upconversion fluorescence can be obtained. The upconversion efficiencies at different pump energies were measured when pumped with a 1064-nm laser beam from a mode-locked Nd:YAG laser. The highest upconversion efficiencies were measured to be 5.8% and 7.6% in dimethyl formamide (DMF) and methanol. The lifetime of the dye in DMF was measured to be 75 ps. The strongest nonlinear absorption was at the wavelength of 940 nm, and the highest upconversion efficiency was at the wavelength of 1030 nm. The difference of the two wavelengths was caused by excited state absorption in the dye at wavelengths shorter than 1000 nm. The dye solution in DMF and methanol show a clear optical power limiting effect.

Journal Article↗

PubMed2002

Photocatalytic decomposition of toluene by TiO2 film as photocatalyst.

This paper reports on the degradation of gaseous toluene by the photocatalytic oxidation process. The photocatalyst, TiO2 film, was prepared by the sol-gel method and was coated on porous nickel. The photocatalytic decomposition of toluene was carried out in a recirculating batch reactor. The factors that affect toluene decomposition were studied, including particle size of the catalyst, initial toluene concentration, flow rate of toluene in the reactor, relative humidity and reactive temperature. In addition, deactivation of the catalyst is also discussed. The experiment results showed that toluene can be decomposed effectively by the photocatalytic oxidation process, and that toluene degradation obeys the first-order reaction.

Air Pollution↗

PubMed2002

[Location of the probe dots in gene chip image with the medialness function].

For acquisition of the gene chip information, how to correctly locate the probe dots in the chip's scanning image is the base of the chip information processing. Here we present a new approach for locating the probe dots in the gene chip image. First, a medialness function, which is good at detection of circle area with radius given in advance, is used for calculating the medialness map in which the center of circle sample area of the gene chip image is disclosed prominently. Then, a method to locate the probe dots center is given based on the medialness map and the 2D space configuration of the probe dots. The experiments show that the new approach correctly locates the probe dots while against noise affection robustly.

Algorithms↗

PubMedDate not supplied

Mesh simplification with hierarchical shape analysis and iterative edge contraction.

This paper presents a novel mesh simplification algorithm. It decouples the simplification process into two phases: shape analysis and edge contraction. In the analysis phase, it imposes a hierarchical structure on a surface mesh by uniform hierarchical partitioning, marks the importance of each vertex in the hierarchical structure, and determines the affected regions of each vertex at the hierarchical levels. In the contraction phase, it also divides the simplification procedure into two steps: half-edge contraction and optimization. In the first step, memoryless quadric metric error and the importance of vertices in the hierarchical structure are combined to determine one operation of half-edge contraction. In the second step, it repositions the vertices in the half-edge simplified mesh by minimizing the multilevel synthesized quadric error on the corresponding affected regions from the immediately local to the more global. The experiments illustrate the competitive results.

Algorithms↗

PubMedDate not supplied

Mesh parameterization by minimizing the synthesized distortion metric with the coefficient-optimizing algorithm.

The parameterization of a 3D mesh into a planar domain requires a distortion metric and a minimizing process. Most previous work has sought to minimize the average area distortion, the average angle distortion, or a combination of these. Typical distortion metrics can reflect the overall performance of parameterizations but discount high local deformations. This affects the performance of postprocessing operations such as uniform remeshing and texture mapping. This paper introduces a new metric that synthesizes the average distortions and the variances of both the area deformations and the angle deformations over an entire mesh. Experiments show that, when compared with previous work, the use of synthesized distortion metric performs satisfactorily in terms of both the average area deformation and the average angle deformation; furthermore, the area and angle deformations are distributed more uniformly. This paper also develops a new iterative process for minimizing the synthesized distortion, the coefficient-optimizing algorithm. At each iteration, rather than updating the positions immediately after the local optimization, the coefficient-optimizing algorithm first update the coefficients for the linear convex combination and then globally updates the positions by solving the Laplace system. The high performance of the coefficient-optimizing algorithm has been demonstrated in many experiments.

Algorithms↗