Experimental investigation on bubble coalescence under nonuniform temperature distribution in reduced gravity.

Results on bubble coalescences from the space experiment of thermocapillary bubble migration conducted on board the Chinese 22nd recoverable satellite are presented in this paper. Some coalescences of large spherical bubbles under microgravity are observed through bubbles staying at the upper side of the test cell. The data of bubble coalescence time are recorded and compared with theoretical predictions, which is based on a theory to describe the tendency of coalescence connected to chemical potential difference. It is implied that the theory is applicable for the experimental data of bubble coalescence. Moreover, the angle between the line of two bubble centers and temperature gradient falled mostly in the range 20 degrees -40 degrees .

Establishment of a cell-based drug screening model for identifying down-regulators of Protein Tyrosine Phosphatase 1B expression.

Protein Tyrosine Phosphatase 1B (PTP1B), an important negative regulator of insulin signaling, is thought to be an attractive therapeutic target for insulin resistance and type 2 diabetes. For the aim of screening PTP1B expression down-regulators, we established the drug screening cellular model based on transcriptional regulation of PTP1B. In this study, the promoter sequences of PTP1B were cloned into pGL3B-neo vector containing luciferase gene and neomycin resistance gene. The recombinant reporter gene vector pGL3B-neo /PTP1B was transfected into CV1 cells and therefore stable cell line, namely SPTP1B, was obtained. With the cell-based reporter gene assay, we detected more than one hundred compounds in microtiter wells. In the screening process, the compound CM107 which had extracted from the traditional Chinese medicinal herbs was identified to repress the activity of PTP1B promoter significantly in mode of dose-dependence.

Establishment of a cell-based drug screening system for identifying selective down-regulators of mPGES-1.

OBJECTIVE: To establish a drug screening system based on transcriptional regulation of microsomal PGE(2) synthase 1 (mPGES-1), cyclooxygenase 1 (COX-1) and 2 (COX-2) for discovering selective down-regulators of mPGES-1. METHODS: The upstream regulatory sequences of mPGES-1, COX-1, COX-2 were respectively cloned into pGL3B-neo vector containing luciferase gene and neomycin resistance gene (the pGL3B-neo vector had been previously constructed by cloning the neomycin resistance gene into the Sal I site of the pGL3-Basic vector). After that, the recombinant reporter gene vectors pGL3B-neo/mPGES-1, pGL3B-neo/COX-1, pGL3B-neo/COX-2 were respectively transfected into A549 cells and therefore stable cell lines, namely M 1, M 2 and M 3, were obtained. Samples were detected then by testing luciferase activity of M 1, M 2 and M 3 cells in microtiter wells to identify compounds that can selectively down-regulate mPGES-1 expression. Through luciferase activity testing, the compounds which had more than 40 % inhibition ratio on M 1 and less than 20 % inhibition ratio on M 2 and M 3 cells could be regarded as hits. RESULTS: Using the cell-based reporter gene assay, we screened compounds for selectively down-regulation of mPGES-1 expression and several compounds were discovered. CONCLUSION: A cell-based drug screening system was established to screen selective down-regulators of mPGES-1 expression, and compound CM188 was identified, which might become a lead compound for novel anti-arthritic drugs.

The mass transfer process and the growth rate of protein crystals.

In this paper, protein crystal growth is studied by a Mach-Zehnder interferometer and an image process system. The interference fringe images are recorded during the crystallization of tetragonal hen egg white lysozyme crystal. Concentration distributions of the protein solution are given from the interference fringe images recorded by the Mach-Zehnder interferometer with a real time servo system of a four-step phase shift. The mass transfer flux and the crystal growth rates are obtained from the concentration distribution. The results show that the observed rates are in accordance with those demonstrated by measurements of the experimental images; therefore the method for determining growth rate by the diffusion process is reasonable.