912 research outputs found
Evaluating Search Systems through Field Codes and Classifications: The Case of the First Published Swedish Nursing Study
The aim of the study was to assess and compare established search systems and
approaches by using the search goal of identifying the first (as in oldest)
nursing-related document, with reference to the first Swedish-affiliated
document, in Scopus, Web of Science, and PubMed (Medline). In doing so, the
objective was to provide concrete examples and illustrate how search systems
and field code searches versus classification-based searches differ. The Scopus
database, Web of Science database aggregator, and the PubMed (Medline) search
engine were used for evaluations. Two different search strategies were compared
in each database: one guided by field codes (i.e., text-based), and one guided
by pre-existing categorizations within database infrastructures. Findings
highlight several factors that are important to consider when formulating and
executing a search strategy. The findings illustrate important aspects of
search systems and search approaches, namely the publication year,
delimitations related to a country or region, and features related to a subject
or research area. The findings also highlight the importance of prioritizing
between different ideals in retrieval. For example, is it more important to
reach the oldest records (publication year), to identify as many records as
possible (exhaustiveness), or to make sure they are as subject-relevant as
possible (e.g., in terms of authors belonging to the same field)? Secondly,
researchers using bibliometric methods to analyze research literature should be
more transparent when reporting searches, as different search systems and
search approaches yield varied numbers and quality of records. While most
bibliometric researchers strive to combine different approaches, this is not
always made clear in reporting.Comment: 12 pages in total (including first page and pages containing
bibliography). 4 table
The secretome of myofibroblasts and its significance in gastric cancer
The microenvironment is important in regulating the behaviour of cancer cells.
Myofibroblasts are a key stromal cell type with important roles in defining
microenvironments in both health and disease by secreting proteins including growth
factors, proteases andextracellular matrix (ECM) components. In the case of gastric
cancer, the myofibroblast population is significantly expanded compared with the
adjacent non-cancer tissue, and with healthy gastric tissue. It has been shown in other
cancers that cancer-associated myofibroblasts (CAMs) can promote tumour
development and progression via secreted proteins such as hepatocyte growth factor
(HGF) and stromal cell-derived factor 1 (SDF-I). In the stomach it has been shown
that changes in the signalling between myofibroblasts and the adjacent epithelial cells
are important in mediating the effects of the gastric pathogen Helicobacter pylori.
Proteomic studies showed that increased secretion of matrix metalloproteinase 7
(MMP7) by the epithelial cells during H pylori infection causes cleavage of insulinlike
growth factor binding protein-5 (IGFBP-5) in the myofibroblast secretome,
resulting in increased bioavailability of IGF-II. This thesis is the first comprehensive
study of gastric myofibroblast secretomes. The aim of this thesis was to define the
differences between gastric CAMs and their adjacent non-cancer tissue myofibroblast
(ANM) counterparts.
This study made use of the unique availability in the group of cultures of
myofibroblasts derived from human gastric carcinoma samples and adjacent noncancer
tissue. In vitro assays revealed that CAMs were more migratory than ANMs,
both in response to IGF-II and when unstimulated. Comparison of CAM and ANM
transcriptomes by gene expression array revealed significant differences, particularly
in genes related to transforming growth factor beta (TGF~) signalling. Myofibroblast conditioned media was used to stimulate AGS cells, a gastric cancer cell line. This
revealed that CAM conditioned media induced greater AGS migration and invasion
than ANM conditioned media. Gene expression array analysis of the stimulated AGS
cells showed that these phenotypic differences were accompanied by significant
changes in gene expression. Again, many of the differences were in genes involved in
TGFp signalling. These experiments suggested that the most important differences
between CAMs and ANMs were in their secretomes.
Quantitative proteomic analysis of the myofibroblast secretomes and proteomes using
the isobaric tagging for relative and absolute quantitation (iTRAQ) system revealed
that a large proportion of the secreted proteins were differentially abundant in CAM
media compared with ANM media. Most of these proteins, including ECM
components and protease inhibitors, were less abundant in the CAM media. Only a
small number of proteins, including proteases, were more abundant in CAM media
than in ANM media. These results suggested a higher level of proteolytic activity in
the CAM secretome. Analysis of the secretome of one CAM and ANM pair by
combined fractional diagonal chromatography (COFRADIC) revealed greater
proteolytic processing of several proteins in CAM media compared with ANM media.
These included proteins with roles in TGFp signalling, ECM components and
proteases.
One protein which was often identified in proteomic experiments as being less
abundant in CAM media than ANM media was TGFp ig-h3. This is a TGFp-induced
extracellular protein with a known role in cellular adhesion. It was shown by Western
blotting that in several cases Pig-h3 was either less abundant or more degraded in
CAM media than ANM media, With proteomic and Western blot data taken together there was evidence for either reduced abundance or increased degradation of ~ig-h3 in
9 out of 11 CAMs compared with their matching ANMs. In vitro assays revealed that
~ig-h3 inhibited AGS cell migration in response to myofibroblast conditioned media.
It was also shown that ~ig-h3 could be cleaved by plasmin, and that inhibiting
urokinase plasminogen activator (uPA), which can convert plasminogen into active
plasmin, also inhibited AGS cell migration in response to myofibroblast conditioned
media.
Together these data show that there are significant differences between gastric CAMs
and ANMs. Many of these differences involve genes and proteins with known roles in
TGF~ signalling, and the key differences are in the secretome. These differences,
including a higher level of proteolytic activity in CAM media, result in a more
migratory response in AGS cells. This suggests that CAMs could be important in
defining a microenvironment in cancer which might promote a more aggressive
cancer phenotype
Weight Status and BMI-Related Traits in Adolescent Friendship Groups and Role of Sociodemographic Factors : The European IDEFICS/I.Family Cohort
Background: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. Methods: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. Results: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. Conclusion: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987).Peer reviewe
The Quantity of Intracluster Light: Comparing Theoretical and Observational Measurement Techniques Using Simulated Clusters
Using a suite of N-body simulations of galaxy clusters specifically tailored
to study the intracluster light (ICL) component, we measure the quantity of ICL
using a number of different methods previously employed in the literature for
both observational and simulation data sets. By measuring the ICL of the
clusters using multiple techniques, we identify systematic differences in how
each detection method identifies the ICL. We find that techniques which define
the ICL solely based on the current position of the cluster luminosity, such as
a surface brightness or local density threshold, tend to find less ICL than
methods utilizing time or velocity information, including stellar particles'
density history or binding energy. The range of ICL fractions (the fraction of
the clusters' total luminosity found in the ICL component) we measure at z=0
across all our clusters using any definition span the range from 9-36%, and
even within a single cluster different methods can change the measured ICL
fraction by up to a factor of two. Separating the cluster's central galaxy from
the surrounding ICL component is a challenge for all ICL techniques, and
because the ICL is centrally concentrated within the cluster, the differences
in the measured ICL quantity between techniques are largely a consequence of
this central galaxy/ICL separation. We thoroughly explore the free parameters
involved with each measurement method, and find that adjusting these parameters
can change the measured ICL fraction by up to a factor of two. While for all
definitions the quantity of ICL tends to increase with time, the ICL fraction
does not grow at a uniform rate, nor even monotonically under some definitions.
Thus, the ICL can be used as a rough indicator of dynamical age, where more
dynamically advanced clusters will on average have higher ICL fractions.Comment: 18 pages, 11 figues. Accepted for publication in Ap
White Dwarf Kinematics vs Mass
We have investigated the relationship between the kinematics and mass of
young (<3x10^8 years) white dwarfs using proper motions. Our sample is taken
from the colour selected catalogues of SDSS (Eisenstein et al. 2006) and the
Palomar-Green Survey (Liebert, Bergeron & Holberg 2005), both of which have
spectroscopic temperature and gravity determinations. We find that the
dispersion decreases with increasing white dwarf mass. This can be explained as
a result of less scattering by objects in the Galactic disk during the shorter
lifetime of their more massive progenitors. A direct result of this is that
white dwarfs with high mass have a reduced scale height, and hence their local
density is enhanced over their less massive counterparts. In addition, we have
investigated whether the kinematics of the highest mass white dwarfs
(>0.95Msun) are consistent with the expected relative contributions of single
star evolution and mergers. We find that the kinematics are consistent with the
majority of high-mass white dwarfs being formed through single star evolution.Comment: 14 pages, 15 figures. Accepted by MNRA
Mapping proteolytic processing in the secretome of gastric cancer-associated myofibroblasts reveals activation of MMP-1, MMP-2, and MMP-3
Cancer progression involves changes in extracellular proteolysis, but the contribution of stromal cell secretomes to the cancer degradome remains uncertain. We have now defined the secretome of a. specific stromal cell type, the rnyofibroblast, in gastric cancer and its modification by proteolysis. SILAC labeling and COFRADIC isolation of methionine containing peptides allowed us to quantify differences in gastric cancer-derived myofibroblasts compared with myofibroblasts from adjacent tissue, revealing increased abundance of several proteases in cancer myofibroblasts including matrix metalloproteinases (MMP)-1 and -3. Moreover, N-terminal COFRADIC analysis identified cancer-restricted proteolytic cleavages, including liberation of the active forms of MMP-1, -2, and -3 from their inactive precursors. In vivo imaging confirmed increased MMP activity when gastric cancer cells were xenografted in mice together with gastric cancer myofibroblasts. Western blot and enzyme activity assays confirmed increased MMP-1, -2, and -3 activity in cancer myofibroblasts, and cancer cell migration assays indicated stimulation by MMP-1, -2, and -3 in cancer-associated rnyofibroblast media. Thus, cancer-derived myofibroblasts differ from their normal counterparts by increased production and activation of MMP-1, -2, and -3, and this may contribute to the remodelling of the cancer cell microenvironment
UV Star Formation Rates in the Local Universe
We measure star formation rates of ~50,000 optically-selected galaxies in the
local universe (z~0.1), spanning a range from gas-rich dwarfs to massive
ellipticals. We obtain dust-corrected SFRs by fitting the GALEX (UV) and SDSS
(optical) photometry to a library of population synthesis models that include
dust attenuation. For star-forming galaxies, our UV-based SFRs compare
remarkably well with those derived from SDSS H alpha. Deviations from perfect
agreement between these two methods are due to differences in the dust
attenuation estimates. In contrast to H alpha, UV provides reliable SFRs for
galaxies with weak or no H alpha emission, and where H alpha is contaminated
with an emission from an AGN. We use full-SED SFRs to calibrate a simple
prescription that uses GALEX UV magnitudes to produce good SFRs for normal
star-forming galaxies. The specific SFR is considered as a function of stellar
mass for (1) star-forming galaxies with no AGN, (2) those hosting an AGN, and
for (3) galaxies without H alpha emission. We find that the three have distinct
star formation histories, with AGN lying intermediate between the star-forming
and the quiescent galaxies. Normal star forming galaxies (without an AGN) lie
on a relatively narrow linear sequence. Remarkably, galaxies hosting a strong
AGN appear to represent the massive continuation of this sequence. Weak AGN,
while also massive, have lower SFR, sometimes extending to the realm of
quiescent galaxies. We propose an evolutionary sequence for massive galaxies
that smoothly connects normal star-forming galaxies to quiescent (red sequence)
galaxies via strong and weak AGN. We confirm that some galaxies with no H alpha
emission show signs of SF in the UV. We derive a UV-based cosmic SFR density at
z=0.1 with smaller total error than previous measurements (abridged).Comment: Accepted for publication in ApJ (Special GALEX Supplement issue - Dec
2007). v2: Typo in Eq. 2 correcte
Catalogs of Hot White Dwarfs in the Milky Way from GALEX's Ultraviolet Sky Surveys. Constraining Stellar Evolution
We present comprehensive catalogs of hot star candidates in the Milky Way,
selected from GALEX far-UV (FUV, 1344-1786 AA) and near-UV (NUV, 1771-2831 AA)
imaging. The FUV and NUV photometry allows us to extract the hottest stellar
objects, in particular hot white dwarfs (WD), which are elusive at other
wavelengths because of their high temperatures and faint optical luminosities.
We generated catalogs of UV sources from two GALEX's surveys: AIS (All-Sky
Imaging Survey, depth ABmag~19.9/20.8 in FUV/NUV) and MIS (Medium-depth Imaging
Survey, depth ~22.6/22.7mag). The two catalogs (from GALEX fifth data release)
contain 65.3/12.6 million (AIS/MIS) unique UV sources with error(NUV)<0.5mag,
over 21,435/1,579 square degrees. We also constructed subcatalogs of the UV
sources with matched optical photometry from SDSS (7th data release): these
contain 0.6/0.9million (AIS/MIS) sources with errors <0.3mag in both FUV and
NUV, excluding sources with multiple optical counterparts, over an area of
7,325/1,103 square degrees. All catalogs are available online. We then selected
28,319(AIS)/9,028(MIS) matched sources with FUV-NUV<-0.13; this color cut
corresponds to stellar Teff hotter than ~18,000 K. An additional color cut of
NUV-r>0.1 isolates binaries with largely differing Teff's, and some intruding
QSOs. Available spectroscopy for a subsample indicates that hot-star candidates
with NUV-r<0.1 have negligible contamination by non-stellar objects. We discuss
the distribution of sources in the catalogs, and the effects of error and color
cuts on the samples. The density of hot-star candidates increases from high to
low Galactic latitudes, but drops on the MW plane due to dust extinction. Our
hot-star counts at all latitudes are better matched by Milky Way models
computed with an initial-final mass relation that favours lower final masses.
(ABRIDGED)Comment: To appear in MNRAS. Better printed in colou
Exploring the promotion of synthons of choice: halogen bonding in molecular lanthanide complexes characterized via X-ray diffraction, luminescence spectroscopy, and magnetic measurements
Promotion of a synthon of choice for the non-covalent assembly of lanthanide tectons represents both a noteworthy challenge and opportunity within LnIII hybrid materials. We have developed a system, wherein some control can be exercised over supramolecular assembly and, as part of continued efforts to improve this process we have generated a family of ten new lanthanide (Ln = Sm3+ – Lu3+) 2,4,6-trichlorobenzoic acid-1,10-phenanthroline molecular complexes. Delineation of criteria for promoting assembly via halogen based interactions was introduced previously and is refined herein based on the characterization of complexes 1–10 via single-crystal X-ray diffraction. Direct comparison of means of supramolecular assembly for 1–10 with isostructural Ln-p-chlorobenzoic acid-1,10-phenanthroline analogues verifies that increasing the number of halogen atoms at the periphery of a tecton is one route that increases the frequency of halogen bonding interactions. Additionally, solid-state visible and near-IR photoluminescence and luminescent lifetime data were collected for complexes 1 (Sm3+), 2 (Eu3+), 4 (Tb3+), 5 (Dy3+), 6 (Ho3+), 7 (Er3+), and 9 (Yb3+) and characteristic emission was observed for all complexes except 6. Further, direct current magnetic susceptibility measurements were carried out for complexes 5 (Dy3+) and 7 (Er3+), and two slow magnetic relaxation processes were characterized using alternating current magnetic susceptibility measurements for 5
Weight Status and BMI-related traits in adolescent friendship groups and role of sociodemographic factors : the European IDEFICS/I.Family Cohort
Background: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. Methods: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. Results: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. Conclusion: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987)
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