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Biomedical subjects

X F Shi

Publications and source records attributed to X F Shi.

7 recordsLinked to original sources
PubMed2005

Transforming growth factor beta1-modified donor cell transfusion induced allo-heart tolerance.

The therapeutic value of the transforming growth factor beta 1 (TGF-beta1) in transplantation has been reported; however, cell-mediated gene therapy using TGF-beta1 is not a widespread application in organ transplantation. This study was performed to evaluate whether TGF-beta1-modified donor spleen cell-specific transfusion could induce tolerogenicity and prolong allograft survival in rat heterotopic heart transplantation. Stable TGF-beta1-transduced spleen cells were established. Wistar rat splenic T-cell responses to donor spleen cells that received TGF-beta1-transduced were severely impaired. Survival of Sprague-Dawley cardiac allografts in Wistar rats given TGF-beta1-modified donor spleen cells (5 x 10(6), 7 days before transplantation), was extended modestly but significantly. Liposome transduction of donor spleen cells to overexpress TGF-beta1 is associated with marked impairment of their T-cell allostimulatory activity but only modest prolongation of allo-heart survival.

Animals↗
PubMed2001

[Analysis of writing age of ballpoint pen ink by thin-layer chromatography].

A method based on using a thin-layer chromatographic method (TLC) for determining changes in dye of ballpoint pen ink developed with writing age. An ink drawn line of 1 cm in length was cut and placed in Eppendorf tube. Extraction was performed with 20 microL ethanol at room temperature for 15 min, and heated in steambath for 10 min. The ethanol solution(4 microL) containing the extracted dyes was then spotted on TLC plate by syringe after cooling. The ballpoint pen ink spots were eluted in a solvent of isopropyl alcohol. Using TLC scanner, the spots on TLC plate were scanned at 580 nm. The relations between ratio of peak heights and writing age were attained. Thus, the information on relative writing age can be obtained. And, the powerful evidence for identifying the age of ballpoint pen ink is provided by this method in the field of forensic science.

Chromatography, Thin Layer↗
PubMed2000

NH-S hydrogen bonding in zinc enzyme model complex with S2N2 binding set studied by normal coordinate analysis of vibrational spectra.

In order to provide theoretical evidence for the existence and effect of NH-S hydrogen bonding in the zinc enzyme model complex [Zn(S-2-C6H4NHCOC6H5)2(1-MeIm)2] (1-MeIm = 1-methylimidazole) in addition to the spectroscopic and crystallographic investigations, normal coordinate analysis (NCA) was carried out using a modified Urey-Bradley force field. The vibrational frequencies of the complex with and without the NH-S hydrogen bonding as well as the corresponding internal coordinates were obtained. The good agreement found between the calculated and observed frequencies in the presence of the NH-S hydrogen bond, supports the reliability of the analysis. The stretching force constant of the NH-S hydrogen bond obtained from the calculation is 0.18 mdyne per A. The calculation shows that the N-H bond is weakened by formation of the NH-S hydrogen bond. The results are indicative of the existence of the NH-S hydrogen bond in the complex.

Hydrogen Bonding↗
PubMed1997

Comparative studies on parallel and antiparallel duplex and triplex DNA.

Parallel strand models for base sequences d(A)10.d(T)10,d(AT)5.d(TA)5, d(G5C5).d(C5G5), d(GC)5.d(CG)5 and d(CTATAGGGAT).d(GATATCCCTA), where reverse Watson-Crick A-T pairing with two H-bonds and reverse Watson-Crick G-C pairing with one H-bond or with two H-bonds were adopted, and three models of d(T)14.d(A)14.d(T)14 triple helix with different strand orientations were built up by molecular architecture and energy minimization. Comparisons of parallel duplex models with their corresponding B-DNA models and comparisons among the three triple helices showed: (i) conformational energies of parallel AT duplex models were a little lower, while for GC duplex models they were about 8% higher than that of their corresponding B-DNA models; (ii) the energy differences between parallel and B-type duplex models and among the three triple helices arose mainly from base stacking energies, especially for GC base pairing; (iii) the parallel duplexes with one H-bond G-C pairs were less stable than those with two H-bonds G-C pairs. The present paper includes a brief discussion about the effect of base stacking and base sequences on DNA conformations.

Animals↗
PubMed1993

[Studies on the antitumor effect of Clerodendrum bungei Steud or C. foetidum Bge].

Clerodendrum B(I) at dosage of 100g/kg ip or sc for 7 days was shown to have antitumor effect on hepatic carcinoma and sarcoma 180 in mice. In the mean time, 100g/kg sc of (I) interrupted 3H-TdR incorporation into DNA of sarcoma 180 cells in mice, 100, 10g/kg sc of (I) could suppress the phagocytic activity of the peritoneal macrophage against the CRBC (chicken red blood cells) in mice, 100g/kg sc of (I) also made the production of serum hemolysin less than one half of that of the control in mice immunized with SRBC. Clerodendrum C at 100g/kg could inhibit the growth of hepatic carcinoma in mice.

Animals↗
PubMed1991

The protective effect of hyperbaric oxygen on hearing during chronic noise exposure.

A series of experiments were conducted on guinea pigs to study the protective effect of hyperbaric oxygen (HBO) on hearing during chronic repeated noise exposure. A 1/3 octave band of noise centered at 1000 Hz was used (126 dB SPL, 1 h daily for 5 d; or 108 dB SPL, 1 h daily, 5 d/week for 4 weeks). Some groups of animals were treated with HBO (2-3 ATA, 1 h duration) before noise exposure. The results indicate that inhalation of HBO (every other day) can markedly reduce noise-induced threshold shift and relieve cochlear damage. The mechanism responsible for HBO protection against noise-induced hearing damage is discussed.

Animals↗