Overexpression of Bax induces apoptosis and enhances drug sensitivity of hepatocellular cancer-9204 cells

AIM: To investigate the role of overexpression of Bax in apoptotic pathways and the response of human hepatocellular cancer (HCC)-9204 cells to cell death induced by adriamycin.METHODS: The whole length of Bax cDNA was transfectrd into human HCC-9204 cells by the method of lipofectamine transfection. An inducible MT-Ⅱ regulatory system was constructed, which allowed controlled expression of protein upon addition of ZnSO4 (100 μmol/L) as an external inducer. Stable transfecting inducible expression vector containing Bax gene was performed. Expression of Bax in protein was analyzed by immunohistochemistry and Western blotting. TUNEL and flow cytometry were used to assess the effect of Bax on apoptosis. Colony assay and tetrazolium blue (MTT) assay were used to evaluate the difference in drug sensitivity of HCC-9204 cells after Bax-transfection.RESULTS: Immunohistochemistry and Western blotting demonstrated that the expression of Bax protein markedly increased in Bax-transfected cells 4 h after the addition cytoplasm and perinuclear region of HCC-9404 cells, and there was ectopic expression in cells with marked condensation of chromatin and cytoplasm (apoptotic cells). Apoptotic index significantly increased in Bax-transfected HCC-9204/Bax cells (3.6 vs 27.2, 4.2 vs 32.3, P＜0.05).Flow cytometry analysis showed a significant sub-G1 peak and apoptosis in 15.4% HCC-9204/Bax cells 24 h after treatment. Furthermore, colony survival rate decreased from 66% (HCC-9204/pMD) to 45% (HCC-9204/Bax) 2 dafter ADR withdrawal. MTT assay result showed that the effects of Bax on cell viability following ADR exposure were significant as compared to the vehicle-transfected HCC-9204/pMD cells (21% vs 44%, P＜0.01).CONCLUSION: Overexpression of Bax not only induces apoptosis, but also sensitizes HCC-9204 cells to cell death induced by adriamycin.

Photodynamics of Methyl-Vinyl Criegee Intermediate:Different Conical Intersections Govern the Fates of Syn/Anti Configurations

Methyl vinyl ketone oxide,an unsaturated four-carbon Criegee intermediate produced from the ozonolysis of isoprene has been recognized to play a key role in determining the tropospheric OH concentration.It exists in four configurations(anti-anti,anti-syn,synanti,and syn-syn)due to two different substituents of saturated methyl and unsaturated vinyl groups.In this study,we have carried out the electronic structure calculation at the multi-configurational CASSCF and multi-state MS-CASPT2 levels,as well as the trajectory surface-hopping nonadiabatic dynamics simulation at the CASSCF level to reveal the different fates of syn/anti configurations in photochemical process.Our results show that the dominant channel for the S1-state decay is a ring closure,isomerization to dioxirane,during which,the syn(C-O)configuration with an intramolecular hydrogen bond shows slower nonadiabatic photoisomerization.More importantly,it has been found for the first time in photochemistry of Criegee intermediate that the cooperation of two heavy groups(methyl and vinyl)leads to an evident pyramidalization of C3 atom in methyl-vinyl Criegee intermediate,which then results in two structurally-independent minimal-energy crossing points(CIs)towards the syn(C-O)and anti(C-O)sides,respectively.The preference of surface hopping for a certain CI is responsible for the different dynamics of each configuration.

Kinetics and FTIR characteristics of the pyrolysis process of poplar wood

The pyrolysis characteristics of residues of poplar （Populus sp.） wood were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared （TG-FTIR） spectrometer. The pyrolysis process was sub- divided into four stages at a rate of 10℃.min-1, varying from 30 to 650℃. Below 180℃, a mass loss occurred for drying and preheating the sample and the onset temperature of pyrolysis ranged between 180-260℃. A significant mass loss 3f 61.4 wt.% occurred between 260-380℃, followed by a slow and continuous mass change with lignin devolatilization. The analysis of kinetic reactions showed that the activation energy （78.29 kJ.mol-1） in the low-temperature section was much larger than that （6.40 kJ-mol-1） in the high-temperature section. The evolved gases formed by thermal degradation 3f poplar wood were simultaneously analyzed by FTIR. It was observed from the main peaks that the emissions evolved during poplar wood pyrolysis were acetic acid, carbon dioxide, carbon monoxide, methane, water, some volatile com- 3ounds of esters, alcohols and aldehydes. The emissions gradually increased with rising temperatures before a strong 3eak around 360℃ and then decreased. Most gaseous products were emitted in the 320-380℃ range, while CO2 was =ontinuously emitted in a wide range from 140-550℃.

Surface Morphology Improvement of Non-Polar a-Plane Ga N Using a Low-Temperature GaN Insertion Layer

We demonstrate that a low-temperature Ga N insertion layer could significantly improve the surface morphology of non-polar a-plane Ga N.The two key factors in improving the surface morphology of non-polar a-plane Ga N are growth temperature and growth time of the Ga N insertion layer.The root-mean-square roughness of a-plane Ga N is reduced by 75%compared to the sample without the Ga N insertion layer.Meanwhile,the Ga N insertion layer is also beneficial for improving crystal quality.This work provides a simple and effective method to improve the surface morphology of non-polar a-plane Ga N.

pH-responsive Polymersome Based on PMCP-b-PDPA as a Drug Delivery System to Enhance Cellular Internalization and Intracellular Drug Release

Choline phosphate （CP） as a novel zwitterion possesses specific and excellent properties compared with phosphorylcholine （PC）, as well as its polymer, such as poly（2-（methacryloyloxy）ethyl choline phosphate） （PMCP）, has been studied extensively due to its unique characteristics of rapid cellular internalization via the special quadrupole interactions with the cell membrane. Recently, we reported a novel PMCP-based drug delivery system to enhance the cellular internalization where the drug was conjugated to the polymer via reversible acylhydrazone bond. Herein, to make full use of this feature of PMCP, we synthesized the diblock copolymer poly（2-（methacryloyloxy）ethyl choline phosphate）-b-poly（2- （diisopropylamino）ethyl methacrylate） （PMCP-b-PDPA）, which could self-assemble into polymersomes with hydrophilic PMCP corona and hydrophobic membrane wall in mild conditions when the pH value is 〉 6.4. It has been found that these polymersomes can be successfully used to load anticancer drug Dox with the loading content of about 11.30 wt%. After the polymersome is rapidly internalized by the cell with the aid of PMCP, the loaded drug can be burst-released in endosomes since PDPA segment is protonated at low pH environment, which renders PDPA to transfer from hydrophobic to hydrophilic, and the subsequent polymersomes collapse thoroughly. Ultimately, the ＂proton sponge＂ effect of PDPA chain can further accelerate the Dox to escape from endosome to cytoplasm to exert cytostatic effects. Meanwhile, the cell viability assays showed that the Dox-loaded polymersomes exhibited significant inhibitory effect on tumor cells, indicating its great potential as a targeted intracellular delivery system with high efficiency.