3,074 research outputs found
miR-638 is a new biomarker for outcome prediction of non-small cell lung cancer patients receiving chemotherapy.
MicroRNAs (miRNAs), a class of small non-coding RNAs, mediate gene expression by either cleaving target mRNAs or inhibiting their translation. They have key roles in the tumorigenesis of several cancers, including non-small cell lung cancer (NSCLC). The aim of this study was to investigate the clinical significance of miR-638 in the evaluation of NSCLC patient prognosis in response to chemotherapy. First, we detected miR-638 expression levels in vitro in the culture supernatants of the NSCLC cell line SPC-A1 treated with cisplatin, as well as the apoptosis rates of SPC-A1. Second, serum miR-638 expression levels were detected in vivo by using nude mice xenograft models bearing SPC-A1 with and without cisplatin treatment. In the clinic, the serum miR-638 levels of 200 cases of NSCLC patients before and after chemotherapy were determined by quantitative real-time PCR, and the associations of clinicopathological features with miR-638 expression patterns after chemotherapy were analyzed. Our data helped in demonstrating that cisplatin induced apoptosis of the SPC-A1 cells in a dose- and time-dependent manner accompanied by increased miR-638 expression levels in the culture supernatants. In vivo data further revealed that cisplatin induced miR-638 upregulation in the serum derived from mice xenograft models, and in NSCLC patient sera, miR-638 expression patterns after chemotherapy significantly correlated with lymph node metastasis. Moreover, survival analyses revealed that patients who had increased miR-638 levels after chemotherapy showed significantly longer survival time than those who had decreased miR-638 levels. Our findings suggest that serum miR-638 levels are associated with the survival of NSCLC patients and may be considered a potential independent predictor for NSCLC prognosis
Analysis and Design of a Multi-Frequency Microstrip Antenna Based on a PBG Substrate
Abstract: Based on the C-shaped microstrip slot antenna, a new photonic band gap substrate for multifrequency microstrip slot antenna is designed. The antenna has a groove been dug below the radiation plate, within which the radiation plate is placed, and air triangular prism column gaps with different height are placed in the substrate periodically. Numerical simulation is performed for the antenna with Ansoft HFSS10.0, which is a kind of simulation software based on Finite Element Method. Comparing with the C-shaped microstrip slot antenna, the resonant frequency of the antenna was reduced by 230 MHz, and the low frequency bandwidth was increased from 12.63 % to 18.95 %, both the radiation and multi-frequency characteristics of this proposed antenna are improved. The result demonstrates that the structure is efficient in improving the antenna gain and radiation directivity by suppressing surface wave of the microstrip antenna. Copyright © 2014 IFSA Publishing, S. L
Effect of fitness on mutual selection in network evolution
AbstractWe propose a new mechanism leading to scale-free networks which is based on the presence of an intrinsic character of a vertex called fitness. In our model, at each vertex i a fitness xi, drawn from a given probability distribution function f(x), is assigned. During network evolution, with rate p we add a vertex j and connect to an existing vertex i of selected preferentially to a linking probability function g(xi,xj) which depends on the fitnesses of the two vertices involved and, with rate 1−p we create an edge between two already existed vertices i and j, with a probability also preferential to the connection function g(xi,xj). For the proper choice of g, the resulting networks have power-law distributions of connectivity and small-world properties, irrespective of the fitness distribution of vertices
Energetics of oxygen-octahedra rotations in perovskite oxides from first principles
We use first-principles methods to study oxygen-octahedra rotations in ABO3
perovskite oxides. We focus on the short-period, perfectly antiphase or
in-phase, tilt patterns that characterize most compounds and control their
physical (e.g., conductive, magnetic) properties. Based on an analytical form
of the relevant potential energy surface, we discuss the conditions for the
stability of polymorphs presenting different tilt patterns, and obtain
numerical results for a collection of thirty-five representative materials. Our
results reveal the mechanisms responsible for the frequent occurrence of a
particular structure that combines antiphase and in-phase rotations, i.e., the
orthorhombic Pbnm phase displayed by about half of all perovskite oxides and by
many non-oxidic perovskites. The Pbnm phase benefits from the simultaneous
occurrence of antiphase and in-phase tilt patterns that compete with each
other, but not as strongly as to be mutually exclusive. We also find that
secondary antipolar modes, involving the A cations, contribute to weaken the
competition between different tilts and play a key role in their coexistence.
Our results thus confirm and better explain previous observations for
particular compounds. Interestingly, we also find that strain effects, which
are known to be a major factor governing phase competition in related (e.g.,
ferroelectric) perovskite oxides, play no essential role as regards the
relative stability of different rotational polymorphs. Further, we discuss why
the Pbnm structure stops being the ground state in two opposite limits, for
large and small A cations, showing that very different effects become relevant
in each case. Our work thus provides a comprehensive discussion on these
all-important and abundant materials, which will be useful to better understand
existing compounds as well as to identify new strategies for materials
engineering
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