1,436 research outputs found
Vascular disruption and bloodābrain barrier dysfunction in intracerebral hemorrhage
Abstract
This article reviews current knowledge of the mechanisms underlying the initial hemorrhage and secondary bloodābrain barrier (BBB) dysfunction in primary spontaneous intracerebral hemorrhage (ICH) in adults. Multiple etiologies are associated with ICH, for example, hypertension, Alzheimerās disease, vascular malformations and coagulopathies (genetic or drug-induced). After the initial bleed, there can be continued bleeding over the first 24Ā hours, so-called hematoma expansion, which is associated with adverse outcomes. A number of clinical trials are focused on trying to limit such expansion. Significant progress has been made on the causes of BBB dysfunction after ICH at the molecular and cell signaling level. Blood components (e.g. thrombin, hemoglobin, iron) and the inflammatory response to those components play a large role in ICH-induced BBB dysfunction. There are current clinical trials of minimally invasive hematoma removal and iron chelation which may limit such dysfunction. Understanding the mechanisms underlying the initial hemorrhage and secondary BBB dysfunction in ICH is vital for developing methods to prevent and treat this devastating form of stroke.http://deepblue.lib.umich.edu/bitstream/2027.42/134526/1/12987_2014_Article_103.pd
The global energy balance of Titan
The global energy budget of planets and their moons is a critical factor to influence the climate change on these objects. Here we report the first measurement of the global emitted power of Titan. Long-term (2004ā2010) observations conducted by the Composite Infrared Spectrometer (CIRS) onboard Cassini reveal that the total emitted power by Titan is (2.84 Ā± 0.01) Ć 10^(14) watts. Together with previous measurements of the global absorbed solar power of Titan, the CIRS measurements indicate that the global energy budget of Titan is in equilibrium within measurement error. The uncertainty in the absorbed solar energy places an upper limit on the energy imbalance of 6.0%
Ancestral Hybridization Facilitated Species Diversification in the Lake Malawi Cichlid Fish Adaptive Radiation.
The adaptive radiation of cichlid fishes in East African Lake Malawi encompasses over 500 species that are believed to have evolved within the last 800,000 years from a common founder population. It has been proposed that hybridization between ancestral lineages can provide the genetic raw material to fuel such exceptionally high diversification rates, and evidence for this has recently been presented for the Lake Victoria region cichlid superflock. Here, we report that Lake Malawi cichlid genomes also show evidence of hybridization between two lineages that split 3-4 Ma, today represented by Lake Victoria cichlids and the riverine Astatotilapia sp. "ruaha blue." The two ancestries in Malawi cichlid genomes are present in large blocks of several kilobases, but there is little variation in this pattern between Malawi cichlid species, suggesting that the large-scale mosaic structure of the genomes was largely established prior to the radiation. Nevertheless, tens of thousands of polymorphic variants apparently derived from the hybridization are interspersed in the genomes. These loci show a striking excess of differentiation across ecological subgroups in the Lake Malawi cichlid assemblage, and parental alleles sort differentially into benthic and pelagic Malawi cichlid lineages, consistent with strong differential selection on these loci during species divergence. Furthermore, these loci are enriched for genes involved in immune response and vision, including opsin genes previously identified as important for speciation. Our results reinforce the role of ancestral hybridization in explosive diversification by demonstrating its significance in one of the largest recent vertebrate adaptive radiations.We acknowledge funding from Wellcome Trust grants WT206194 and WT207492 (H.S. and R.D.), the European Research Council, ERC CoG āCICHLID~Xā (617585) and Swiss National Science Foundation, grant nr. 176039 (W.S) and the Royal Society ā Leverhulme Trust Africa Awards AA100023 and AA130107 to MJG, BPN and GFT
Alteration of Differentiation Potentials by Modulating GATA Transcription Factors in Murine Embryonic Stem Cells
Background. Mouse embryonic stem (ES) cells can be differentiated in vitro by aggregation and/or retinoic acid (RA) treatment. The principal differentiation lineage in vitro is extraembryonic primitive endoderm. Dab2, Laminin, GATA4, GATA5, and GATA6 are expressed in embryonic primitive endoderm and play critical roles in its lineage commitment. Results. We found that in the absence of GATA4 or GATA5, RA-induced primitive endoderm differentiation of ES cells was reduced. GATA4 (ā/ā) ES cells express higher level of GATA5, GATA6, and hepatocyte nuclear factor 4 alpha marker of visceral endoderm lineage. GATA5 (ā/ā) ES cells express higher level of alpha fetoprotein marker of early liver development. GATA6 (ā/ā) ES cells express higher level of GATA5 as well as mesoderm and cardiomyocyte markers which are collagen III alpha-1 and tropomyosin1 alpha. Thus, deletion of GATA6 precluded endoderm differentiation but promoted mesoderm lineages. Conclusions. GATA4, GATA5, and GATA6 each convey a unique gene expression pattern and influences ES cell differentiation. We showed that ES cells can be directed to avoid differentiating into primitive endoderm and to adopt unique lineages in vitro by modulating GATA factors. The finding offers a potential approach to produce desirable cell types from ES cells, useful for regenerative cell therapy
Glycyl- l -Glutamine Disposition in Rat Choroid Plexus Epithelial Cells in Primary Culture: Role of PEPT2
The purpose of this research was to determine the polarity and directionality of the PEPT2-mediated uptake and transepithelial transport of the neuropeptide glycyl- l -glutamine (GlyGln) in choroid plexus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41508/1/11095_2005_Article_5261.pd
Role of PEPT2 in the Choroid Plexus Uptake of Glycylsarcosine and 5-Aminolevulinic Acid: Studies in Wild-Type and Null Mice
Purpose . To determine the importance of PEPT2 in the uptake of glycylsarcosine (GlySar) and 5-aminolevulinic acid (5-ALA) in mouse choroid plexus whole tissue.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41506/1/11095_2004_Article_492483.pd
Responsivity of the differential-intensity surface plasmon resonance instrument
Surface plasmon resonance is used for the sensitive measurement of minute concentrations of bio-analytes and probing of electrochemical processes. Typical refractive index sensitivity, for the intensity approach, is around 10ā6 refractive index units (RIUs). A better sensitivity has been suggested by developing a differential-intensity detection method. This method relies on the excitation of surface plasmons using a weakly focused beam with the average angle of incidence equal to the resonance angle, while the reflected light is detected using a bi-cell photodiode. The Bi-cell signal is processed by calculating the difference between its two units, normalized to their sum. This ratio estimates the shift in the resonance angle using a model that represents the resonance curve with a quadratic function. However, this model does not explain the effects of parameters such as the angular width of the excitation beam and the specifications of the sensing structure on the systemās response. This paper presents a detailed evaluation of the responsivity using experimental and theoretical approaches, which can predict the effect of the different parameters, paving the way towards the investigation of a better sensitivity and the optimization of the systemās design for different applications
M dwarf Stars - The By-Product of X-Ray Selected AGN Candidates
X-ray loud M dwarfs are a major source of by-product (contamination) in the
X-ray band of the multiwavelength quasar survey (MWQS). As a by-product, the
low dispersion spectra of 22 M dwarfs are obtained in which the spectra of 16
sources are taken for the first time. The spectral types and distance of the
sample are given based on spectral indices CaH2, CaH3, and TiO5. The parameter
{\zeta}TiO/CaH is calculated to make the metallicity class separation among
dwarfs, subdwarfs and extreme subdwarfs. We also discuss the distributions in
the diagrams of Log(Lx/Lbol) versus spectral type and infrared colors.Comment: 10 pages, 26 figures, accepted for publication in Research in
Astronomy and Astrophysics (RAA
Deprojected analysis of Abell 1835 observed with Chandra and compared with XMM-Newton
Using a deprojection technique, we study the X-ray properties of the galaxy
cluster Abell 1835 observed with Chandra, including temperature, abundance,
electron density, gas mass fraction, and total mass. A comparison with the
results without deprojection shows that the properties do not change much. When
we compare the results with those of XMM-Newton, the difference between the
temperature profiles derived from Chandra and XMM-Newton data still exists,
even if the point-spread function effect of XMM-Newton is corrected. To
investigate the reasons for the difference, we used the spectra to
cross-calibrate the temperatures. They show that the Chandra spectra can be
fitted well with XMM-Newton temperatures. Furthermore, we derive the electron
density profile from Chandra data with XMM-Newton temperatures and calculate
the projected mass, which is consistent with the XMM-Newton mass and a little
lower than the weak lensing mass at r_500. Thus, it seems that the temperature
derived from XMM-Newton may be more reliable.Comment: 7 pages, 5 figures, accepted for publication in A&
Impurity states in antiferromagnetic Iron Arsenides
We explore theoretically impurity states in the antiferromagnetic
spin-density wave state of the iron arsenide. Two types of impurity models are
employed: one has only the intraband scattering while the other has both the
intraband and interband scattering with the equal strength. Interestingly, the
impurity bound state is revealed around the impurity site in the energy gap for
both models. However, the impurity state is doubly degenerate with respect to
spin for the first case; while the single impurity state is observed in either
the spin-up or spin-down channel for the second one. The impurity-induced
variations of the local density of states are also examined.Comment: 4 pages, 2 figure
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