804 research outputs found
Temporal Effects of Cyclic Stretching on Distribution and Gene Expression of Integrin and Cytoskeleton by Ligament Fibroblasts In Vitro
Cyclic stretching is pivotal to maintenance of the ligaments. However, it is still not clear when ligament fibroblasts switch on expression of genes related to the mechanotransduction pathway in response to cyclic stretching. This in vitro study investigated, using ligament fibroblasts, the time-dependent changes in distribution and gene expression of β1 integrin, the cytoskeleton, and collagens after the application of 6% cyclic stretching at a frequency of 0.1 Hz for 3 hr on silicon membranes. We carried out confocal laser scanning microscopy to demonstrate changes in distribution of these components as well as quantitative real-time RT-PCR to quantify levels of these gene expression both during application of cyclic stretching and at 0, 2, 6, 12, and 18 hr after the termination of stretching. Control (unstretched) cells were used at each time point. Within 1 hr of the application of stretching, the fibroblasts and their actin stress fibers became aligned in a direction perpendicular to the major axis of stretch, whereas control (unstretched) cells were randomly distributed. In response to cyclic stretching, upregulation of actin at the mRNA level was first observed within 1 hr after the onset of stretching, while upregulation of β1 integrin and type I and type III collagens was observed between 2 and 12 hr after the termination of stretching. These results indicate that the fibroblasts quickly modify their morphology in response to cyclic stretching, and subsequently they upregulate the expression of genes related to the mechanotransduction pathway mainly during the resting period after the termination of stretching
An archaeology of borders: qualitative political theory as a tool in addressing moral distance
Interviews, field observations and other qualitative methods increasingly are being used to inform the construction of arguments in normative political theory. This article works to demonstrate the strong salience of some kinds of qualitative material for cosmopolitan arguments to extend distributive boundaries. The incorporation of interviews and related qualitative material can make the moral claims of excluded others more vivid and possibly more difficult to dismiss by advocates of strong priority to compatriots in distributions. Further, it may help to promote the kind of perspective taking that has been associated with actually motivating a willingness to aid by individuals. Illustrative findings are presented from field work conducted for a normative project on global citizenship, including interviews with unauthorized immigrants and the analysis of artifacts left behind on heavily used migrant trails
Early onset torsion dystonia (Oppenheim's dystonia)
Early onset torsion dystonia (EOTD) is a rare movement disorder characterized by involuntary, repetitive, sustained muscle contractions or postures involving one or more sites of the body. A US study estimated the prevalence at approximately 1 in 30,000. The estimated prevalence in the general population of Europe seems to be lower, ranging from 1 in 330,000 to 1 in 200,000, although precise numbers are currently not available. The estimated prevalence in the Ashkenazi Jewish population is approximately five to ten times higher, due to a founder mutation. Symptoms of EOTD typically develop first in an arm or leg in middle to late childhood and progress in approximately 30% of patients to other body regions (generalized dystonia) within about five years. Distribution and severity of symptoms vary widely between affected individuals. The majority of cases from various ethnic groups are caused by an autosomal dominantly inherited deletion of 3 bp (GAG) in the DYT1 gene on chromosome 9q34. This gene encodes a protein named torsinA, which is presumed to act as a chaperone protein associated with the endoplasmic reticulum and the nuclear envelope. It may interact with the dopamine transporter and participate in intracellular trafficking, although its precise function within the cell remains to be determined. Molecular genetic diagnostic and genetic counseling is recommended for individuals with age of onset below 26 years, and may also be considered in those with onset after 26 years having a relative with typical early onset dystonia. Treatment options include botulinum toxin injections for focal symptoms, pharmacological therapy such as anticholinergics (most commonly trihexiphenydil) for generalized dystonia and surgical approaches such as deep brain stimulation of the internal globus pallidus or intrathecal baclofen application in severe cases. All patients have normal cognitive function, and despite a high rate of generalization of dystonia, 75% of those patients are able to maintain ambulation and independence, and therefore a comparatively good quality of life, with modern treatment modalities
Atomistic modelling of large-scale metal film growth fronts
We present simulations of metallization morphologies under ionized sputter
deposition conditions, obtained by a new theoretical approach. By means of
molecular dynamics simulations using a carefully designed interaction
potential, we analyze the surface adsorption, reflection, and etching reactions
taking place during Al physical vapor deposition, and calculate their relative
probability. These probabilities are then employed in a feature-scale
cellular-automaton simulator, which produces calculated film morphologies in
excellent agreement with scanning-electron-microscopy data on ionized sputter
deposition.Comment: RevTeX 4 pages, 2 figure
Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations
In this work, we present the first AMBER observations, of the Wolf-Rayet and
O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the
telescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered
spectrally dispersed visibilities, as well as differential and closure phases,
with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret
these data in the context of a binary system with unresolved components,
neglecting in a first approximation the wind-wind collision zone flux
contribution. We show that the AMBER observables result primarily from the
contribution of the individual components of the WR+O binary system. We discuss
several interpretations of the residuals, and speculate on the detection of an
additional continuum component, originating from the free-free emission
associated with the wind-wind collision zone (WWCZ), and contributing at most
to the observed K-band flux at the 5% level. The expected absolute separation
and position angle at the time of observations were 5.1±0.9mas and
66±15° respectively. However, we infer a separation of
3.62+0.11-0.30 mas and a position angle of 73+9-11°. Our analysis thus
implies that the binary system lies at a distance of 368+38-13 pc, in agreement
with recent spectrophotometric estimates, but significantly larger than the
Hipparcos value of 258+41-31 pc
A thermal‐gradient approach to variable‐temperature measurements resolved in space
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155923/1/jcr2te5056.pd
Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
We present the first NIR spectro-interferometry of the LBV Eta Carinae. The K
band observations were performed with the AMBER instrument of the ESO Very
Large Telescope Interferometer using three 8.2m Unit Telescopes with baselines
from 42 to 89m. The aim of this work is to study the wavelength dependence of
Eta Car's optically thick wind region with a high spatial resolution of 5 mas
(11 AU) and high spectral resolution. The medium spectral resolution
observations (R=1,500) were performed in the wavelength range around both the
HeI 2.059 micron and the Br gamma 2.166 micron emission lines, the high
spectral resolution observations (R=12,000) only in the Br gamma line region.
In the K-band continuum, a diameter of 4.0 +/-0.2 mas (Gaussian FWHM, fit range
28-89m) was measured for Eta Car's optically thick wind region. If we fit
Hillier et al. (2001) model visibilities to the observed AMBER visibilities, we
obtain 50 % encircled-energy diameters of 4.2, 6.5 and 9.6mas in the 2.17
micron continuum, the HeI, and the Br gamma emission lines, respectively. In
the continuum near the Br gamma line, an elongation along a position angle of
120+/-15 degrees was found, consistent with previous VLTI/VINCI measurements by
van Boekel et al. (2003). We compare the measured visibilities with predictions
of the radiative transfer model of Hillier et al. (2001), finding good
agreement. Furthermore, we discuss the detectability of the hypothetical hot
binary companion. For the interpretation of the non-zero differential and
closure phases measured within the Br gamma line, we present a simple geometric
model of an inclined, latitude-dependent wind zone. Our observations support
theoretical models of anisotropic winds from fast-rotating, luminous hot stars
with enhanced high-velocity mass loss near the polar regions.Comment: 22 pages, 14 figures, 2 tables; A&A in pres
GC content of early metazoan genes and its impact on gene expression levels in mammalian cell lines
With the genomes available for many animal clades, including the early-branching metazoans, one can readily study the functional conservation of genes across a diversity of animal lineages. Ectopic expression of an animal protein in, for instance, a mammalian cell line is a generally used strategy in structure–function analysis. However, this might turn out to be problematic in case of distantly related species. Here we analyzed the GC content of the coding sequences of basal animals and show its impact on gene expression levels in human cell lines, and, importantly, how this expression efficiency can be improved. Optimization of the GC3 content in the coding sequences of cadherin, alpha-catenin, and paracaspase of Trichoplax adhaerens dramatically increased the expression of these basal animal genes in human cell lines
Persistent Cellular Motion Control and Trapping Using Mechanotactic Signaling
Chemotactic signaling and the associated directed cell migration have been extensively studied owing to their importance in emergent processes of cellular aggregation. In contrast, mechanotactic signaling has been relatively overlooked despite its potential for unique ways to artificially signal cells with the aim to effectively gain control over their motile behavior. The possibility of mimicking cellular mechanotactic signals offers a fascinating novel strategy to achieve targeted cell delivery for in vitro tissue growth if proven to be effective with mammalian cells. Using (i) optimal level of extracellular calcium ([Ca2[superscript +] ][subscript ext] = 3 mM) we found, (ii) controllable fluid shear stress of low magnitude (σ < 0.5 Pa), and (iii) the ability to swiftly reverse flow direction (within one second), we are able to successfully signal Dictyostelium discoideum amoebae and trigger migratory responses with heretofore unreported control and precision. Specifically, we are able to systematically determine the mechanical input signal required to achieve any predetermined sequences of steps including straightforward motion, reversal and trapping. The mechanotactic cellular trapping is achieved for the first time and is associated with a stalling frequency of 0.06 ~ 0.1 Hz for a reversing direction mechanostimulus, above which the cells are effectively trapped while maintaining a high level of directional sensing. The value of this frequency is very close to the stalling frequency recently reported for chemotactic cell trapping [Meier B, et al. (2011) Proc Natl Acad Sci USA 108:11417–11422], suggesting that the limiting factor may be the slowness of the internal chemically-based motility apparatus.SUTD-MIT International Design Centre (Grant IDG31400104
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