606 research outputs found
Expression, Tissue Distribution and Function of miR-21 in Esophageal Squamous Cell Carcinoma
Objective:MiR-21 is an oncomir expressed by malignant cells and/or tumor microenvironment components. In this study we focused on understanding the effects of stromal miR-21 on esophageal malignant cells.Design:MiR-21 expression was evaluated in formalin-fixed paraffin-embedded samples from patients with esophageal squamous-cell carcinoma (SCC) by quantitative RT-PCR. MiR-21 tissue distribution was visualized with in situ hybridization. A co-culture system of normal fibroblasts and esophageal cancer cells was used to determine the effects of fibroblasts on miR-21 expression levels, and on SCC cell migration and invasion.Results:MiR-21 was overexpressed in SCCs, when compared to the adjacent non-tumor tissues (P = 0.0007), and was mainly localized in the cytoplasm of stromal cells adjacent to malignant cells. Accordingly, miR-21 expression was increased in tumors with high versus low stromal content (P = 0.04). When co-cultured with normal fibroblasts, miR-21 expression was elevated in SCC cells (KYSE-30), while its expression was restricted to fibroblasts when co-cultured with adenocarcinoma cells (OE-33 and FLO-1). MiR-21 was detected in conditioned media of cancer cell lines, illustrating the release of this miRNA into the environment. Co-culturing with normal fibroblasts or addition of fibroblast conditioned media caused a significant increase in cell migration and invasion potency of KYSE-30 cells (P<0.0001). In addition, co-culturing cancer cells with fibroblasts and expression of miR-21 induced the expression of the cancer associated fibroblast (CAF) marker S100A4.Conclusions:MiR-21 expression is mostly confined to the SCC stroma and its release from fibroblasts influences the migration and invasion capacity of SCC cells. Moreover, miR-21 may be an important factor in "activating" fibroblasts to CAFs. These findings provide new insights into the role of CAFs and the extracellular matrix in tumor microenvironment formation and in tumor cell maintenance, and suggest miR-21 may contribute to cellular crosstalk in the tumor microenvironment. © 2013 Nouraee et al
Spin diffusion in doped semiconductors
The behavior of spin diffusion in doped semiconductors is shown to be
qualitatively different than in undoped (intrinsic) ones. Whereas a spin packet
in an intrinsic semiconductor must be a multiple-band disturbance, involving
inhomogeneous distributions of both electrons and holes, in a doped
semiconductor a single-band disturbance is possible. For n-doped nonmagnetic
semiconductors the enhancement of diffusion due to a degenerate electron sea in
the conduction band is much larger for these single-band spin packets than for
charge packets, and can exceed an order of magnitude at low temperatures even
for equilibrium dopings as small as 10^16 cm^-3. In n-doped ferromagnetic and
semimagnetic semiconductors the motion of spin packets polarized antiparallel
to the equilibrium carrier spin polarization is predicted to be an order of
magnitude faster than for parallel polarized spin packets. These results are
reversed for p-doped semiconductors.Comment: 8 pages, 4 figure
Spin transport theory in ferromagnet/semiconductor systems with non-collinear magnetization configurations
We present a comprehensive theory of spin transport in a non-degenerate
semiconductor that is in contact with multiple ferromagnetic terminals. The
spin dynamics in the semiconductor is studied during a perturbation of a
general, non-collinear magnetization configuration and a method is shown to
identify the various configurations from current signals. The conventional
Landauer-B\"{u}ttiker description for spin transport across Schottky contacts
is generalized by the use of a non-linearized I-V relation, and it is extended
by taking into account non-coherent transport mechanisms. The theory is used to
analyze a three terminal lateral structure where a significant difference in
the spin accumulation profile is found when comparing the results of this model
with the conventional model.Comment: 17 pages, 10 figure
beta-decay study of Cu-77
A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator
with the aim to deduce its beta-decay properties and to obtain spectroscopic
information on Zn-77. Neutron-rich copper isotopes were produced by means of
proton- or neutron-induced fission reactions on U-238. After the production,
Cu-77 was selectively laser ionized, mass separated and sent to different
detection systems where beta-gamma and beta-n coincidence data were collected.
We report on the deduced half-live, decay scheme, and possible spin assignment
of 77Cu
Flemish adolescents' perceptions of cigarette plain packaging:a qualitative study with focus group discussions
OBJECTIVES: To find out whether there is a potential impact of the appearance of a plain cigarette package on the smoking perceptions and behavioural intentions of Flemish adolescents. DESIGN: We performed a cross-sectional study using the qualitative method of focus group discussions. SETTING: Flemish adolescents. PARTICIPANTS: We performed eight focus group discussions, in which 55 adolescents took part, 32 female and 23 male. Inclusion criteria were: Flemish male and female 15-year-olds to 16-year-olds and 17-year-olds to 18-year-olds attending regular high-school education or vocational training who were current or had ever been smokers. OUTCOME MEASURE (PLANNED AS WELL AS MEASURED): The opinions and perceptions of young Flemish smokers regarding the impact of cigarette packaging on their smoking behaviour. RESULTS: Plain packages are perceived as less attractive, cheap and unreliable for young people. Because of the unattractiveness of the plain packaging, the health warnings catch the eye much more strongly. CONCLUSIONS: In this first scientific study in Flanders on this topic, it emerged that plain packaging could be a strong policy tool to reduce the number of adolescents starting smoking. Validation of these findings by conducting a quantitative survey in the same target group is recommended
The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results
The highest precision in direct mass measurements is obtained with Penning
trap mass spectrometry. Most experiments use the interconversion of the
magnetron and cyclotron motional modes of the stored ion due to excitation by
external radiofrequency-quadrupole fields. In this work a new excitation
scheme, Ramsey's method of time-separated oscillatory fields, has been
successfully tested. It has been shown to reduce significantly the uncertainty
in the determination of the cyclotron frequency and thus of the ion mass of
interest. The theoretical description of the ion motion excited with Ramsey's
method in a Penning trap and subsequently the calculation of the resonance line
shapes for different excitation times, pulse structures, and detunings of the
quadrupole field has been carried out in a quantum mechanical framework and is
discussed in detail in the preceding article in this journal by M. Kretzschmar.
Here, the new excitation technique has been applied with the ISOLTRAP mass
spectrometer at ISOLDE/CERN for mass measurements on stable as well as
short-lived nuclides. The experimental resonances are in agreement with the
theoretical predictions and a precision gain close to a factor of four was
achieved compared to the use of the conventional excitation technique.Comment: 12 pages, 14 figures, 2 table
Respiratory Health Symptoms among Students Exposed to Different Levels of Air Pollution in a Turkish City
In this study, we aimed to investigate the frequency of respiratory health symptoms among high school students attending schools at industrial, urban and rural areas in a Turkish city. Three schools located in different zones of the city having different pollution characteristics were chosen based on the pollutant distribution maps using Geographical Information Systems (GIS) software. A cross-sectional survey was performed among 667 high school students in the schools. Outdoor and indoor nitrogen dioxide (NO2) and ozone (O3) concentrations were also measured by passive samplers in the same schools to investigate possible routes of exposure. Chronic pulmonary disease (OR = 1.49; 95%CI: 1.11–1.99; p = 0.008), tightness in the chest (OR = 1.57; 95%CI: 1.22–2.02; p = 0.001), morning cough (OR = 1.81 95%CI: 1.19–2.75; p = 0.006) were higher among students in the industrial zone where nitrogen dioxide and ozone levels were also highest. There were no indoor sources of nitrogen dioxide and ozone exists in the schools except for the dining hall. As a conclusion, this study has noticed that air pollution and respiratory health problems among high school students are high in industrial zones and the use of passive samplers combined with GIS is an effective tool that may be used by public health researchers to identify pollutant zones and persons at risk
Magnetic moments of Cu and Cu nuclei measured by in-source laser spectroscopy
We have obtained information on the atomic hyperfine splitting and, hence, on magnetic moments in neutron rich Cu isotopes by scanning the frequency of the narrow-band laser of the first excitation step in the resonance ionization laser ion source. The deduced magnetic moments are Cu, I = 1) = +2.48(2)(7) ; Cu, I=6) = +1.24(4)(6) and Cu, I=1) = +1.86(4)(6) ; Cu, I=6) = +1.50(7)(8). The results of the scans analysis point out on existence of a new isomer in Cu. It's deduced magnetic moment is (-)3.50(7)(11) that is in a good agreement with I=3 assignment. The method of in-source atomic spectroscopy, as well as the analysis of the obtained data, is described. The results are discussed in terms of single-particle configurations coupled to the Ni core
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