No abstract

A regulator of the protein phosphatase 2A (PP2A), a4, has been implicated in a variety of functions that regulate many cellular processes. To explore the role of a4 in human cell transformation and tumorigenesis, we show that a4 is highly expressed in human cells transformed by chemical carcinogens including benzo(a)pyrene, aflatoxin B 1 , N-methyl-N 0 -nitro-N-nitrosoguanidine, nickel sulfate and in several hepatic and lung cancer cell lines. In addition, overexpression of a4 was detected in 87.5% (74/80) of primary hepatocellular carcinomas, 84.0% (21/25) of primary lung cancers and 81.8% (9/11) of primary breast cancers, indicating that a4 is ubiquitously highly expressed in human cancer. Functional studies revealed that elevated a4 expression results in an increase in cell proliferation, promotion of cell survival and decreased PP2A-attributable activity. Importantly, ectopic expression of a4 permits non-transformed human embryonic kidney cells (HEKTER) and L02R cells to form tumors in immunodeficient mice. Furthermore, we show that the highly expressed a4 in transformed cells or human tumors is not regulated by DNA hypomethylation. A microRNA, miR-34b, that suppresses the expression of a4 through specific binding to the 3 0 -untranslated region of a4 is downregulated in transformed or human lung tumors. Taken together, these observations identify that a4 possesses an oncogenic function. Reduction of PP2A activity due to an enhanced a4-PP2A interaction contributes directly to chemical carcinogen-induced tumorigenesis.

The temperature- and bias-dependent photocurrent spectra of very long wavelength GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations. It is found that the peak response wavelength will shift as the bias and temperature change. Aided by band structure calculations, we propose a model of the double excited states and explain the experimental observations very well. In addition, the working mechanisms of the quasi-bound state confined in the quantum well, including the processes of tunneling and thermionic emission, are also investigated in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. These obtained results provide a full understanding of the bound-to-quasi-bound state and the bound-to-quasi-continuum state transition, and thus allow for a better optimization of QWIPs performance.

No abstract

ABSTRACT. Cinnamon is the main component of Sanyangxuedai, which is one of the effective traditional Chinese medicines for treating malignancies. Leukemia is a prevalent malignant disease that Sanyangxuedai has been used to treat. Although successful in several studies, there is a lack of solid evidence as to why Sanyangxuedai has an effect on leukemia, and little is known about the underlying mechanisms. In this study, the active ingredients of cinnamon were isolated, purified, and identified. The transwell transport pool formed with the Caco-2 cell model was used to filter the active ingredients of cinnamon by simulating the gastrointestinal barrier in vitro. Moreover, the cell morphology, cell cycle status, apoptosis status, and antigenic variation of the cell surface antigens were observed and measured in K562 cells after treatment with the active ingredients of cinnamon. Our results showed that 50-75 µM was a safe concentration of cinnamon extract for treatment of K562 cells for 72 h. The cinnamon extract caused growth inhibition of K562 cells. Cinnamon extract seemed to arrest the cells at the G1 stage and increased the apoptosis rate significantly. Interestingly, cinnamon extract treatment upregulated the expression of erythroid and myeloid differentiation antigens and downregulated that of the megakaryocytic differentiation antigens in a dose-dependent manner. Our findings indicate that cinnamon extract from Sanyangxuedai may be effective for treating leukemia.

(index any site), 37.6% (CI95:36.1-39.1) after second, 21.2% (CI95:18.0-25.0) after third, with the majority of subsequent fractures occurring in the first 2 years post fracture. Risk of subsequent MOF was highest in the first 6 months following index fracture; the adjusted relative risk (RR) of MOF was 2.2 (CI95:2.1-2.2) following any fragility fracture, 4.5 (CI95:4.2-4.9) following a vertebral fracture and 1.9 (CI95:1.8-2.1) following a hip fracture. After a second fracture, these RRs were 2.6 (CI95:2.4-2.8), 3.8 (CI95:2.9-5.2) and 2.0 (CI95:1.9-2.1); and after the third fracture, the RR was 1.5 (CI95:1.5-1.5). ConClusions: Fracture risk significantly increases rapidly within 6 months following a fragility fracture, remains very elevated in the subsequent 2 years and persists over 5 years. The relative risk manifests within 6 months and gradually declines over 5 years following the fracture. A patient who has suffered any fragility fracture requires prompt intervention to minimize that risk and avoid significant personal, economic and societal burden.

No abstract

Micro-photoluminescence (-PL) line scanning across a single V-groove, GaAs/AlGaAs quantum wire (QWR) has been performed at room temperature, revealing a clear spatial-dependence of the PL. After fitting each PL spectrum by multi-Gaussian line shapes, intensity profiles of each PL component from confined structures have been obtained as functions of the scanning position. The PL quenching of a side-wall quantum well (SQWL) has been recognized in a certain area in the vicinity of the QWR and is interpreted by carrier transfer into the QWR within effective transfer length. By simulating the carriertransfer process from SQWL to QWR as a convolution of a step function for carrier distribution and a Gaussian function for exciting laser irradiance, the effective transfer length of about 1.8 Ϯ 0.3 m has, therefore, been concluded.