97 research outputs found
Migraine and brain lesions. Data from the population-based CAMERA Study
The objective of this thesis was to elucidate whether migraine is a true and independent risk factor for brain lesions. We summarized migraine symptoms, diagnostic criteria, epidemiologic data, and assumed pathophysiology. We described the existing literature on the relationship between migraine and ischemic stroke and cerebral white matter lesions (WML). The findings of the population-based CAMERA MRI-study are reported. Posterior circulation (cerebellar) infarcts occurred in 8% of migraineurs with aura (adjusted-OR 13.7). Female migraineurs were at increased risk of high-deep-WML-load (OR 2.0). Risks increased with attack frequency, suggestive of a causal relationship. We detailed on the infarcts and other infratentorial lesions. Findings of higher iron-concentration in deep brain nuclei in younger migraineurs suggest that repeated migraine attacks are associated with changes in regions known to be involved in central pain processing and migraine pathophysiology. In addition, we showed that migraineurs had more syncope-related autonomic-nervous-system symptoms, and we identified frequent syncope and orthostatic insufficiency as independent risk factors for high-DWML-load. With these data, there is now strong evidence that migraine is indeed an independent risk factor for silent brain lesions. The real extent of brain injury in migraine patients in the general population is likely underestimated.Netherlands Hearth Foundation (NHF-1997B108).
Nederlandse Hoofdpijn Vereniging.
Foundation Imago, Oegstgeest
Migraine and vascular disease biomarkers: A population-based case-control study.
Background The underpinnings of the migraine-stroke association remain uncertain, but endothelial activation is a potential mechanism. We evaluated the association of migraine and vascular disease biomarkers in a community-based population. Methods Participants (300 women, 117 men) were recruited as a part of the Dutch CAMERA 1 (Cerebral Abnormalities in Migraine, an Epidemiologic Risk Analysis) study. Participants were aged 30-60 (mean 48) years, 155 migraine had with aura (MA), 128 migraine without aura (MO), and 134 were controls with no severe headaches. Plasma concentrations of fibrinogen, Factor II, D-dimer, high sensitivity C-reactive protein (hs-CRP), and von Willebrand factor antigen were compared between groups, also stratifying by sex. Results Fibrinogen and hs-CRP were elevated in migraineurs compared to controls. In logistic regression analyses, MO and MA had increased likelihood of elevated fibrinogen, and MA had increased likelihood of elevated Factor II and hs-CRP. Fibrinogen and Factor II were associated with MA in women but not men. In the migraine subgroup, the total number of years of aura, but not headache, predicted elevated hs-CRP, and the average number of aura, but not headache, attacks predicted all biomarkers but Factor II. Conclusions Elevated vascular biomarkers were associated with migraine, particularly MA, as well as with years of aura and number of aura attacks
No Evidence for Evolution in the Far-Infrared-Radio Correlation out to z ~ 2 in the eCDFS
We investigate the 70 um Far-Infrared Radio Correlation (FRC) of star-forming
galaxies in the Extended Chandra Deep Field South (ECDFS) out to z > 2. We use
70 um data from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL),
which comprises the most sensitive (~0.8 mJy rms) and extensive far-infrared
deep field observations using MIPS on the Spitzer Space Telescope, and 1.4 GHz
radio data (~8 uJy/beam rms) from the VLA. In order to quantify the evolution
of the FRC we use both survival analysis and stacking techniques which we find
give similar results. We also calculate the FRC using total infrared luminosity
and rest-frame radio luminosity, qTIR, and find that qTIR is constant (within
0.22) over the redshift range 0 - 2. We see no evidence for evolution in the
FRC at 70 um which is surprising given the many factors that are expected to
change this ratio at high redshifts.Comment: 18 pages, 13 figures. Accepted for publication in Ap
Large-Scale Gravitational Instability and Star Formation in the Large Magellanic Cloud
Large-scale star formation in disk galaxies is hypothesized to be driven by
global gravitational instability. The observed gas surface density is commonly
used to compute the strength of gravitational instability, but according to
this criterion star formation often appears to occur in gravitationally stable
regions. One possible reason is that the stellar contribution to the
instability has been neglected. We have examined the gravitational instability
of the Large Magellanic Cloud (LMC) considering the gas alone, and considering
the combination of collisional gas and collisionless stars. We compare the
gravitationally unstable regions with the on-going star formation revealed by
Spitzer observations of young stellar objects. Although only 62% of the massive
young stellar object candidates are in regions where the gas alone is unstable,
some 85% lie in regions unstable due to the combination of gas and stars. The
combined stability analysis better describes where star formation occurs. In
agreement with other observations and numerical models, a small fraction of the
star formation occurs in regions with gravitational stability parameter Q > 1.
We further measure the dependence of the star formation timescale on the
strength of gravitational instability, and quantitatively compare it to the
exponential dependence expected from numerical simulations.Comment: Accepted for publication in ApJ, 10 pages, 5 figure
Scalelength of disc galaxies
We have derived disk scale lengths for 30374 non-interacting disk galaxies in
all five SDSS bands. Virtual Observatory methods and tools were used to define,
retrieve, and analyse the images for this unprecedentedly large sample
classified as disk/spiral galaxies in the LEDA catalogue. Cross correlation of
the SDSS sample with the LEDA catalogue allowed us to investigate the variation
of the scale lengths for different types of disk/spiral galaxies. We further
investigat asymmetry, concentration, and central velocity dispersion as
indicators of morphological type, and are able to assess how the scale length
varies with respect to galaxy type. We note however, that the concentration and
asymmetry parameters have to be used with caution when investigating type
dependence of structural parameters in galaxies. Here, we present the scale
length derivation method and numerous tests that we have carried out to
investigate the reliability of our results. The average r-band disk scale
length is 3.79 kpc, with an RMS dispersion of 2.05 kpc, and this is a typical
value irrespective of passband and galaxy morphology, concentration, and
asymmetry. The derived scale lengths presented here are representative for a
typical galaxy mass of , and the RMS dispersion
is larger for more massive galaxies. Distributions and typical trends of scale
lengths have also been derived in all the other SDSS bands with linear
relations that indicate the relation that connect scale lengths in one passband
to another. Such transformations could be used to test the results of
forthcoming cosmological simulations of galaxy formation and evolution of the
Hubble sequence.Comment: Accepter for publication in MNRAS (15 pages, 15 figures, and 3
tables
Dilating and fracturing side struts of open cell stents frequently used in pediatric cardiac interventions—An in vitro study
Background: Open cell stents are frequently used in interventional therapy of congenital heart disease. Overstenting of vessel branches may necessitate strut dilation. Methods and Results: The strut size achievable in Bard Valeo and Cook Formula stents, and the pressure necessary to fracture struts was assessed. In addition, a self expanding stent (Optimed SinusflexDS) was also tested. With the original balloon at nominal pressure, in Valeo stents side struts could be dilated to approximately 90% of the nominal stent diameter, in Formula stents to approximately 80%. With larger high pressure woven balloons, strut size increased to approximately 125% in Valeo stents, and to approximately 105% in the Formula. Strut fracture can connect two adjoining struts. Pressures were dependent on the balloon utilized. Sidestruts of the Sinusflex could lastingly overdilated with large balloons only. Conclusion: Dilation and overdilation of side struts in open cell stents can be achieved. Dependent on the clinical context, the original balloon used to place the premounted stent can be used to achieve strut dilation, but woven high pressure balloons maybe safer for patients. Should a larger diameter be required, these high pressure woven balloons can achieve bigger diameters and even strut fracture
Star Formation in Isolated Disk Galaxies. II. Schmidt Laws and Efficiency of Gravitational Collapse
(Abridged). We model gravitational instability in a wide range of isolated
disk galaxies, using GADGET, a three-dimensional, smoothed particle
hydrodynamics code. The model galaxies include a dark matter halo and a disk of
stars and isothermal gas. The global Schmidt law observed in disk galaxies is
quantitatively reproduced by our models. We find that the surface density of
star formation rate directly correlates with the strength of local
gravitational instability. The local Schmidt laws of individual galaxies in our
models show clear evidence of star formation thresholds. Our results suggest
that the non-linear development of gravitational instability determines the
local and global Schmidt laws, and the star formation thresholds.Comment: 21 pages, 15 figures, to appear on ApJ March 2006. (Paper I is ApJ
626, 823, 2005, or astro-ph/0501022
Cortical glutamate and gamma-aminobutyric acid over the course of a provoked migraine attack, a 7 Tesla magnetic resonance spectroscopy study
Enhanced activity of the glutamatergic system has been linked to migraine pathophysiology. The present study aimed to assess the involvement of the glutamatergic system in the onset of attacks. We provoked attacks by infusion of glyceryl trinitrate (GTN; 0.5 µg/kg/min over 20 min) in 24 female episodic migraineurs without aura and 13 female age-matched healthy controls. Over the course of a single day participants were scanned three times at fixed time slots (baseline before GTN infusion, 90 min and 270 min after start of GTN infusion). Single-volume proton magnetic resonance spectra (1H–MRS) were acquired at 7 Tesla from a volume of interest (VOI, 2x2x3 cm) in the visual cortex. We assessed the concentrations of glutamate, its major precursor glutamine, and its product gamma-aminobutyric acid (GABA) over the course of a provoked attack. The preictal state was defined as the period after GTN infusion until the migraine-like headache started, independent of possible experienced premonitory symptoms, and the ictal state was defined as the period with provoked migraine-like headache. Data were analyzed using a linear mixed-effect model for repeated measures. Glutamate and glutamine levels did not change from interictal to the preictal and ictal state. GABA levels increased from interictal towards the preictal state for migraine patients compared with healthy controls. We conclude that high resolution 7T MRS is able to show changes in the glutamatergic system towards a triggered migraine attack, by revealing an increased GABA concentration associated with the onset of a migraine attack
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