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951.
952.
Two new sorbicillinoids, 1 and 2 , together with a novel benzofuranone derivative named phialofurone ( 3 ), were isolated from a deep‐sea sediment‐derived fungus, Phialocephala sp. Their structures were established on the basis of spectroscopic data. All compounds displayed cytotoxic effects against P388 (IC50 values of 11.5±1.4, 0.1±0.1, and 0.2±0.01 μM , resp.) and K562 (IC50 values of 22.9±0.8, 4.8±0.3 and 22.4±0.9 μM , resp.) cell lines. 相似文献
953.
954.
Junyong Zhang Yonghui Deng Dong Gu Shutao Wang Lan She Renchao Che Zhong‐Sheng Wang Bo Tu Songhai Xie Dongyuan Zhao 《Liver Transplantation》2011,1(2):241-248
A novel ligand‐assisted assembly approach is demonstrated for the synthesis of thermally stable and large‐pore ordered mesoporous titanium dioxide with a highly crystalline framework by using diblock copolymer poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) as a template and titanium isopropoxide (TIPO) as a precursor. Small‐angle X‐ray scattering, X‐ray diffraction (XRD), transmission electron microscopy (TEM), high‐resolution scanning electron microscopy, and N2‐sorption measurements indicate that the obtained TiO2 materials possess an ordered primary cubic mesostructure with large, uniform pore diameters of about 16.0 nm, and high Brunauer–Emmett–Teller surface areas of ~112 m2 g?1, as well as high thermal stability (~700 °C). High resolution TEM and wide‐angle XRD measurements clearly illustrate the high crystallinity of the mesoporous titania with an anatase structure in the pore walls. It is worth mentioning that, in this process, in addition to tetrahydrofuran as a solvent, acetylacetone was employed as a coordination agent to avoid rapid hydrolysis of the titanium precursor. Additionally, stepped evaporation and heating processes were adopted to control the condensation rate and facilitate the assembly of the ordered mesostructure, and ensure the formation of fully polycrystalline anatase titania frameworks without collapse of the mesostructure. By employing the obtained mesoporous and crystallized TiO2 as the photoanode in a dye‐sensitized solar cell, a high power‐conversion efficiency (5.45%) can be achieved in combination with the N719 dye, which shows that this mesoprous titania is a great potential candidate as a catalyst support for photonic‐conversion applications. 相似文献
955.
Despite its potent antitumor effect, clinical use of Doxorubicin is limited because of serious side effects including myocardial
toxicity. Understanding the cellular mechanism involved in this process in a better manner is beneficial for optimizing Doxorubicin
treatment. In the current study, the authors focus on the AMP-activated protein kinase (AMPK) in the said process. In this
study, the authors discovered for the first time that Doxorubicin induces AMPK activation in cultured rat embryonic ventricular
myocardial H9c2 cells. Reactive oxygen species (ROS)-dependent LKB1 activation serves as the upstream signal for AMPK activation
by Doxorubicin. Evidence in support of the activation of AMPK contributing to Doxorubicin-induced H9c2 cell death/apoptosis—probably
by modulating multiple downstream signal targets, including regulating JNK, p53, and inhibiting mTORC1—is provided in this
article. 相似文献
956.
To investigate the expression and biological significance of Leptin, Leptin receptor, Vascular Endothelial Growth Factor (VEGF),
and CD34 protein in colorectal carcinoma tissues. The expression of Leptin, Leptin receptor, VEGF, and CD34 was detected in
68 cases of colorectal carcinoma tissues, paired para-carcinoma tissues and normal colorectal tissues by Immunohistochemical
SP Method. The results and related clinicopathological data were analyzed. The positive rate of Leptin, Leptin receptor, and
VEGF was significantly higher in colorectal carcinoma tissues than that in paired para-carcinoma tissues and normal colorectal
tissues. The expression of Leptin, Leptin receptor, and VEGF was correlated with grade of tumor differentiation, depth of
bowel wall invasion, lymph node metastasis, Dukes stage, distant metastasis, and lympho/vascular tumor embolization. Microvessel
density (MVD) value in colorectal carcinoma was significantly higher than that in para-carcinoma tissues and normal colorectal
tissues, and the density in para-carcinoma tissues was higher than that in normal colorectal tissues. The expression of Leptin,
Leptin receptor, VEGF, and MVD value in colorectal carcinoma was positively correlated. In conclusion, microvessel density
value is an important index of the growth, invasion, and metastasis of colorectal carcinoma. The binding of Leptin and Leptin
receptor promotes the proliferation of colorectal carcinoma cells. The synergy between Leptin and VEGF accelerates the angiogenesis
in colorectal carcinoma and accelerates the invasion and metastasis of the tumor cells. 相似文献
957.
Tyrosine phosphorylation of mitochondrial pyruvate dehydrogenase kinase 1 is important for cancer metabolism 总被引:1,自引:0,他引:1
Hitosugi T Fan J Chung TW Lythgoe K Wang X Xie J Ge Q Gu TL Polakiewicz RD Roesel JL Chen GZ Boggon TJ Lonial S Fu H Khuri FR Kang S Chen J 《Molecular cell》2011,44(6):864-877
Many tumor cells rely on aerobic glycolysis instead of oxidative phosphorylation for their continued proliferation and survival. Myc and HIF-1 are believed to promote such a metabolic switch by, in part, upregulating gene expression of pyruvate dehydrogenase (PDH) kinase 1 (PDHK1), which phosphorylates and inactivates mitochondrial PDH and consequently pyruvate dehydrogenase complex (PDC). Here we report that tyrosine phosphorylation enhances PDHK1 kinase activity by promoting ATP and PDC binding. Functional PDC can form in mitochondria outside of the matrix in some cancer cells and PDHK1 is commonly tyrosine phosphorylated in human cancers by diverse oncogenic tyrosine kinases localized to different mitochondrial compartments. Expression of phosphorylation-deficient, catalytic hypomorph PDHK1 mutants in cancer cells leads to decreased cell proliferation under hypoxia and increased oxidative phosphorylation with enhanced mitochondrial utilization of pyruvate and reduced tumor growth in xenograft nude mice. Together, tyrosine phosphorylation activates PDHK1 to promote the Warburg effect and tumor growth. 相似文献
958.
Kim SG Jung BW Kim H 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2011,159(2):103-108
Phenoloxidase (PO) activity is a major component of the innate immune response in arthropods. In this study, we characterized PO activity from the hair crab Erimacrus isenbeckii, which inhabits very cold regions (2.4-3.4°C) of the Bering Sea. Hemocyte lysate supernatant (HLS) prepared from E. isenbeckii was inactive HLS until activated by nonspecific agents such as sodium dodecyl sulfate and trypsin, and elicitors such as lipopolysaccharide and lipoteichoic acid from the cell wall constituent of bacteria. The PO activity was maximal at 4°C, decreased slightly at temperatures up to 60°C, and fell rapidly at 80°C. Both L-DOPA and catechol were efficient substrates for the PO (EC 1.10.3.1), with K(m) values of 0.96 and 1.15mM, respectively, whereas tyrosine and hydroquinone were not. We isolated a protein fraction from HLS as a hexamer of 75kDa units with 216.7-fold higher PO activity than that of the HLS. The N-terminal amino acid analysis of an isolated protein revealed 80% sequence identity to hemocyanins from other crabs. These results suggest that cold-adapted hemocyanin-derived PO activity is important to the survival of these crabs. This is the first report of a crab PO activity with broad temperature stability extending into the cold environment. 相似文献
959.
Liang Zhang Zhongyang Ding Peng Xu Yuhong Wang Zhenghua Gu Zhu Qian Guiyang Shi Kechang Zhang 《Biotechnology and Bioprocess Engineering》2011,16(3):457-461
Tyrosinase is a key enzyme in the biosynthesis of melanin, and the use of inhibitors against tyrosinase can prevent hyperpigmentation
by inhibiting enzymatic oxidation. However, the current use of tyrosine inhibitors is limited by their low activities and
high toxicities. The aim of the present research was to develop novel whitening agents, or tyrosinase-targeted medicine, from
a submerged culture of the fungus Ganoderma lucidum. Methyl lucidenate F was isolated from the ethanol-soluble-acidic components (ESACs) of G. lucidum, with the structure of ESACs elucidated via UV, LC-MS, and 13C-NMR spectral analysis. The tyrosinase inhibitory activity was measured using catechol as a substrate. Methyl lucidenate
F displayed uncompetitive inhibition of the potato tyrosinase activity, for which Lineweaver-Burk plots revealed a maximum
reaction rate (V
max) of 0.4367/min, Michaelis constant (K
m) of 6.765 mM and uncompetitive inhibition constant (K
i) of 19.22 μM. Meanwhile, methyl lucidenate F (tetra cyclic triterpenoid) exhibited high tyrosinase inhibitory activity, with
an IC50 of 32.23 μM. These results suggest that methyl lucidenate F may serve as a potential candidate for skin-whitening agents. 相似文献
960.