Biomedical subjects

Xiangrong Liu

Publications and source records attributed to Xiangrong Liu.

5 recordsLinked to original sources

PubMed2005

The Hsp90 inhibitor 17-allylamide-17-demethoxygeldanamycin induces apoptosis and differentiation of Kasumi-1 harboring the Asn822Lys KIT mutation and down-regulates KIT protein level.

Heat shock protein 90 (Hsp90) serves as a chaperone for a number of cell signaling proteins, including many tyrosine and serine/threonine kinases, which are involved in proliferation and/or survival. The benzoquinone ansamycin geldanamycin has been shown to bind to Hsp90 and to specifically inhibit this chaperone's function, resulting in client protein destabilization. 17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a chemical derivative of geldanamycin. KIT is the receptor for stem cell factor (SCF) and required for normal hematopoiesis. Mutations in c-Kit result in ligand-independent tyrosine kinase activity and uncontrolled cell proliferation. Kasumi-1 is t(8;21) acute myeloid leukemia (AML) cell line harboring mutated KIT with Asn822Lys substitution. Our present studies demonstrate that 17-AAG inhibits Kasumi-1 cells proliferation and exerts apoptosis- and differentiation-inducing effects in a dose- and time-dependent manner. The growth-inhibitory IC50 value for 17-AAG treatment is 0.62mumol/L. Characteristic apoptotic features were confirmed by morphology, internucleosomal DNA fragmentation, and annexin V staining. 17-AAG also causes the G0/G1 block of Kasumi-1 cells. Significantly, 17-AAG-induced apoptosis of Kasumi-1 cells is associated with a decline in KIT protein level. Our findings strongly suggest that 17-AAG might be an effective therapeutic agent targeting AML cells harboring mutated KIT.

Apoptosis↗

PubMed2004

A new DNA computing model for the NAND gate based on induced hairpin formation.

Hairpin structure of DNA molecules has been widely employed in a variety of biosensors and in nanoscale molecular assembly applications. For example, the well known molecular beacons can report the presence of specific nucleic acids in homogeneous solutions with high accuracy. Recently, Smith et al. proposed the induction of hairpin formation through sequence-specific binding of a small-molecule ligand to a G-G mismatch. Not only did this method offer great flexibility in controlling hairpin formation, more importantly the induced hairpin maintains high degree of sensitivity toward specific hybridization. In this contribution, we present a theoretical model for the logical NAND gate based on induced hairpin formation.

Computer Simulation↗

PubMed2004

[Preparation of chitosan-collagen sponge and its application in wound dressing].

We have prepared a wound dressing made from chitosan and collagen. Its clinical curative effect was detected. Chitosan solution was put into purified collagen solution. Then, the solution became sponge by means of freeze drying, and it was subjected to a series of toxicology tests, including acute toxicity, stimulation test, allergic and hemolysis tests, as well as the clinical test of openning trauma in orthopedics. All of the results of toxicology tests were negative. The chitosan-collagen sponge could not only accelerate the speed of curing but also restrain the extravasate. Therefore, the chitosan-collagen sponge has good biocompatibility and clinical curative effect. It is a prospective security-biomaterial for medical use.

Biocompatible Materials↗

PubMed2002

Biologic characteristics of fibroblast cells cultured from the knee ligaments.

OBJECTIVE: To culture fibroblast cells from the knee ligaments and to study the biological characteristics of these cells. METHODS: Cells of the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL) from New Zealand white rabbit were cultured in vitro. Cellular growth and expression of the collagen were analyzed. Moreover, an in vitro wound closure model was established and the healing of the ACL and the MCL cells was compared. RESULTS: Maximal growth for all these cells were obtained with Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, but RPMI 1640 and Ham's F12 media were not suitable to maintain these cells. Morphology of both ACL and MCL cells from New Zealand white rabbit was alike in vitro, but the MCL cells grew faster than the ACL cells. Both cell types produced similar amount of collagen in culture, but the ratio of collage type I to type III produced by ACL cells was higher than that produced by MCL cells. Wound closure assay showed that at 36 hours after injury, cell-free zones created in the ACL cultures were occupied partially by the ACL cells; in contrast, the wounded zone in the MCL cultures was almost completely covered by the cells. CONCLUSIONS: Although the ACL cells and the MCL cells from New Zealand white rabbit show similar appearance in morphology in culture, the cellular growth and the biochemical synthesis of collagen as well as the healing in vitro were significantly different. These differences in intrinsic properties of the two types of cells in vitro might contribute to the differential healing potentials of these ligaments in vivo.

Animals↗

PubMedDate not supplied

Solving the 3-SAT problem based on DNA computing.

The 3-SAT problem is an NP-complete problem, and many algorithms based on DNA computing have been proposed for solving it since Adleman's pioneering work. This paper presents a new algorithm based on the literal string strategy proposed by Sakamoto et al. Simulation results show that the maximal number of literal strings produced during the computing process is greatly reduced. Moreover, the length of the literal strings is also reduced from m to n at most.

Algorithms↗