Biomedical subjects

X D Shi

Publications and source records attributed to X D Shi.

3 recordsLinked to original sources

PubMed2001

Entropy-driven phase transition in binary mixtures.

Based on the principle of entropy maximum, a transparent method to study the phase separation is proposed. The excluded volume effects of binary mixtures of hard spheres with two different diameters are analyzed and the role of entropy is emphasized. As a result of the entropy variation caused by the packing of large spheres, there is a critical volume fraction to denote the phase boundary. It is shown that the variation of free volume fraction is influenced by the ratio alpha=d(L)/d(S) of large to small sphere diameters and the ratio x=eta(L)/(eta(L)+eta(S)) of large-sphere volume fraction to the total volume fraction of large- and small-spheres. We introduce a modification factor beta to describe the overlap degree of two large spheres excluded volumes when they pack together. The critical volume fractions for large-sphere packing with different values of alpha and x are calculated, and the corresponding phase boundaries are determined. Our results are in quite good agreement with previous experimental measurements.

Journal Article↗

PubMed2001

[Regulation of Chinese medicine bailong and hexamethylene bisacetamide on cyclin dependent kinase inhibitor P16 genes in human cancer cell].

OBJECTIVE: To study the regulation of bailong, a Chinese herbal anticancer preparation and hexamethylene bisacetamide (HMBA) on cyclin dependent kinase inhibitor P16 (CKI-P16) genes in human cancer cells. METHODS: The expression of CKI-P16 in different human cancer cells treated by Bailong or HMBA under different condition, was examined using Northern hybridization, Western blotting assay, etc. RESULTS: After being treated by Bailong or HMBA, the P16 expression increased. This effect was closely related to co-regulation of cAMP-PKA and DAC-PKC signal pathway. When PKA pathway was blocked with PKA inhibitor, the P16 expression decreased, while PKC pathway was blocked, it enhanced. CONCLUSION: (1) The low P16 expression in G1 phase of cancer cell, as compared with that in S, G2 and M phases, might be an important factor responsible to the incompetence of P16 in inhibiting effectively the malignant change of cancer cell. (2) Mechanism of Bailong and HMBA on cancer cell proliferation inhibition might be correlated with the enhancement of P16 expression in G1 phase of cancer cells. (3) Regulation and expression of Bailong and HMBA on P16 showed the common character of Chinese and western medicine in regulating cancer cells. (4) This study elucidated that upstream of P16 was related to cAMP/PKC signal pathway closely.

Acetamides↗

PubMed2000

Resistance of helicobacter pylori to metronidazole, tetracycline and amoxycillin.

Resistance to metronidazole, tetracycline and amoxycillin, and beta-lactamase production were determined for 153 clinical isolates of Helicobacter pylori. Of these isolates, 77.8% were resistant to metronidazole (MIC > 8 mg/L), 58.8% to tetracycline (MIC > 16 mg/L) and 71.9% to amoxycillin (MIC > 0.5 mg/L); 39.2% were multiresistant. Resistance to metronidazole was more common in isolates from females than in those from males (P < 0.05). None of the isolates produced beta-lactamase, so the mechanism of amoxycillin resistance was not linked to production of beta-lactamase.

Amoxicillin↗