4,741 research outputs found
[3,3âČ-DihyÂdroxy-3,3âČ-bisÂ(pyridin-3-yl-ÎșN)-1,1âČ-(pyridine-2,6-diÂyl)dipropan-1-one](nitrato-Îș2 O,OâČ)silver(I)
In the title compound, a new macrocyclic metal complex, [Ag(NO3)(C21H15N3O4)], all non-H atoms are in a close-to-planar geometry (except for the nitrate anion), with a maximum out-of-plane deviation of 0.327â
(6)â
Ă
for a pyridine C atom. The dihedral angle between the least-squares plane through the [3,3âČ-dihyÂdroxy-3,3âČ-bisÂ(pyridin-3-yl)-1,1âČ-(pyridine-2,6-diÂyl)dipropan-1-one]silver(I) fragment and the nitrate anion is 31.29â
(13)°. The molÂecular structure is stabilized by several inter- and intraÂmolecular OâHâŻO and CâHâŻO hydrogen bonds. The AgI atom is coordinated by two pyridine N atoms and two O atoms of the nitrate anion in a geometry intermediate between tetrahedral and square-planar
sscMap: An extensible Java application for connecting small-molecule drugs using gene-expression signatures
Background: Connectivity mapping is a process to recognize novel
pharmacological and toxicological properties in small molecules by comparing
their gene expression signatures with others in a database. A simple and robust
method for connectivity mapping with increased specificity and sensitivity was
recently developed, and its utility demonstrated using experimentally derived
gene signatures.
Results: This paper introduces sscMap (statistically significant connections'
map), a Java application designed to undertake connectivity mapping tasks using
the recently published method. The software is bundled with a default
collection of reference gene-expression profiles based on the publicly
available dataset from the Broad Institute Connectivity Map 02, which includes
data from over 7000 Affymetrix microarrays, for over 1000 small-molecule
compounds, and 6100 treatment instances in 5 human cell lines. In addition, the
application allows users to add their custom collections of reference profiles
and is applicable to a wide range of other 'omics technologies.
Conclusions: The utility of sscMap is two fold. First, it serves to make
statistically significant connections between a user-supplied gene signature
and the 6100 core reference profiles based on the Broad Institute expanded
dataset. Second, it allows users to apply the same improved method to
custom-built reference profiles which can be added to the database for future
referencing. The software can be freely downloaded from
http://purl.oclc.org/NET/sscMapComment: 3 pages, 1 table, 1 eps figur
3-(2-BromoÂbenzÂyl)-1-methyl-1H-imidazol-3-ium bromide
In the title compound, C11H12BrN2
+·Brâ, the imidazole and phenyl rings are nearly perpendicular, making a dihedral angle of 87.71â
(7)°. The crystal structure is stabilized by non-classical interÂmolecular CâHâŻBr hydrogen bonds and inversion-related molÂecules are linked through ÏâÏ interÂactions between the imidazole ring systems [centroidâcentroid distance = 3.472â
(6)â
Ă
]
Electromagnetic form factor of pion from N_f=2+1 dynamical flavor QCD
We present a calculation of the electromagnetic form factor of the pion in
flavor lattice QCD. Calculations are made on the PACS-CS gauge field
configurations generated using Iwasaki gauge action and Wilson-clover quark
action on a lattice volume with the lattice spacing estimated as
fm at the physical point. Measurements of the form factor are
made using the technique of partially twisted boundary condition to reach small
momentum transfer as well as periodic boundary condition with integer momenta.
Additional improvements including random wall source techniques and a judicious
choice of momenta carried by the incoming and outgoing quarks are employed for
error reduction. Analyzing the form factor data for the pion mass at MeV and 296 MeV, we find that the NNLO SU(2) chiral perturbation
theory fit yields for the pion charge radius
at the physical pion mass. Albeit the error is quite large, this is consistent
with the experimental value of . Below MeV, we find that statistical fluctuations in the pion two- and
three-point functions become too large to extract statistically meaningful
averages on a spatial volume. We carry out a sample calculation on a
lattice with the quark masses close to the physical point, which
suggests that form factor calculations at the physical point become feasible by
enlarging lattice sizes to .Comment: 28 pages, 14 figure
A simple and robust method for connecting small-molecule drugs using gene-expression signatures
Interaction of a drug or chemical with a biological system can result in a
gene-expression profile or signature characteristic of the event. Using a
suitably robust algorithm these signatures can potentially be used to connect
molecules with similar pharmacological or toxicological properties. The
Connectivity Map was a novel concept and innovative tool first introduced by
Lamb et al to connect small molecules, genes, and diseases using genomic
signatures [Lamb et al (2006), Science 313, 1929-1935]. However, the
Connectivity Map had some limitations, particularly there was no effective
safeguard against false connections if the observed connections were considered
on an individual-by-individual basis. Further when several connections to the
same small-molecule compound were viewed as a set, the implicit null hypothesis
tested was not the most relevant one for the discovery of real connections.
Here we propose a simple and robust method for constructing the reference
gene-expression profiles and a new connection scoring scheme, which importantly
allows the valuation of statistical significance of all the connections
observed. We tested the new method with the two example gene-signatures (HDAC
inhibitors and Estrogens) used by Lamb et al and also a new gene signature of
immunosuppressive drugs. Our testing with this new method shows that it
achieves a higher level of specificity and sensitivity than the original
method. For example, our method successfully identified raloxifene and
tamoxifen as having significant anti-estrogen effects, while Lamb et al's
Connectivity Map failed to identify these. With these properties our new method
has potential use in drug development for the recognition of pharmacological
and toxicological properties in new drug candidates.Comment: 8 pages, 2 figures, and 2 tables; supplementary data supplied as a
ZIP fil
Controlled interfacial assembly of 2D curved colloidal crystals and jammed shells
Assembly of colloidal particles on fluid interfaces is a promising technique
for synthesizing two-dimensional micro-crystalline materials useful in fields
as diverse as biomedicine1, materials science2, mineral flotation3 and food
processing4. Current approaches rely on bulk emulsification methods, require
further chemical and thermal treatments, and are restrictive with respect to
the materials employed5-9. The development of methods that exploit the great
potential of interfacial assembly for producing tailored materials have been
hampered by the lack of understanding of the assembly process. Here we report a
microfluidic method that allows direct visualization and understanding of the
dynamics of colloidal crystal growth on curved interfaces. The crystals are
periodically ejected to form stable jammed shells, which we refer to as
colloidal armour. We propose that the energetic barriers to interfacial crystal
growth and organization can be overcome by targeted delivery of colloidal
particles through hydrodynamic flows. Our method allows an unprecedented degree
of control over armour composition, size and stability.Comment: 18 pages, 5 figure
Non-linear soil behavior on freight vs passenger lines
Upgrading existing passenger-only railway lines to carry freight traffic is becoming increasingly desirable. This is challenging because freight trains have larger axle loads and thus can have a negative effect on track longevity, particularly on ballasted lines supported by sub-optimal ground conditions. These additional loads can cause large subgrade strains resulting in non-linear behaviour, which should be considered before permitting freight vehicles on passenger routes. To do so requires the modelling of non-linear soil behaviour which is challenging. Therefore, this paper presents a solution in the form of an equivalent non-linear, thin layer element soil model, coupled to an analytical track model. The model has low computational demand and can adjust subgrade stiffness depending upon strain levels. Therefore, it is well suited to computing track response induced by freight trains. This paper validates the model and then uses it to compare the differences between the response of a ballasted line to freight and passenger vehicles
Computational modelling of cancerous mutations in the EGFR/ERK signalling pathway
This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2009 Orton et al.BACKGROUND: The Epidermal Growth Factor Receptor (EGFR) activated Extracellular-signal Regulated Kinase (ERK) pathway is a critical cell signalling pathway that relays the signal for a cell to proliferate from the plasma membrane to the nucleus. Deregulation of the EGFR/ERK pathway due to alterations affecting the expression or function of a number of pathway components has long been associated with numerous forms of cancer. Under normal conditions, Epidermal Growth Factor (EGF) stimulates a rapid but transient activation of ERK as the signal is rapidly shutdown. Whereas, under cancerous mutation conditions the ERK signal cannot be shutdown and is sustained resulting in the constitutive activation of ERK and continual cell proliferation. In this study, we have used computational modelling techniques to investigate what effects various cancerous alterations have on the signalling flow through the ERK pathway. RESULTS: We have generated a new model of the EGFR activated ERK pathway, which was verified by our own experimental data. We then altered our model to represent various cancerous situations such as Ras, B-Raf and EGFR mutations, as well as EGFR overexpression. Analysis of the models showed that different cancerous situations resulted in different signalling patterns through the ERK pathway, especially when compared to the normal EGF signal pattern. Our model predicts that cancerous EGFR mutation and overexpression signals almost exclusively via the Rap1 pathway, predicting that this pathway is the best target for drugs. Furthermore, our model also highlights the importance of receptor degradation in normal and cancerous EGFR signalling, and suggests that receptor degradation is a key difference between the signalling from the EGF and Nerve Growth Factor (NGF) receptors. CONCLUSION: Our results suggest that different routes to ERK activation are being utilised in different cancerous situations which therefore has interesting implications for drug selection strategies. We also conducted a comparison of the critical differences between signalling from different growth factor receptors (namely EGFR, mutated EGFR, NGF, and Insulin) with our results suggesting the difference between the systems are large scale and can be attributed to the presence/absence of entire pathways rather than subtle difference in individual rate constants between the systems.This work was funded by the Department of Trade and Industry (DTI), under their Bioscience Beacon project programme. AG was funded by an industrial PhD studentship from Scottish Enterprise and Cyclacel
Biocompatibility of subretinal parylene-based Ti/Pt microelectrode array in rabbit for further artificial vision studies
To evaluate the biocompatibility of subretinal implanted parylene-based Ti/Pt microelectrode arrays (MEA). Eyes were enucleated 3Â months after MEAs were implanted into the subretinal space of rabbits. Morphological changes of the retinas were investigated by H&E staining. Immunohistochemical staining for glial fibrillary acidic protein and opsin were performed to evaluate changes in Muller cells and photoreceptors in the retinas. Retina tissue around the array remained intact. Photoreceptor degeneration and glial cell activation were observed in the retina overlaying the MEA implant. However, the cells in the inner retinal layers were preserved. Photoreceptor degeneration and glial cell activation at the MEAâretina interface are expected to be a normal reaction to implantation. Material used in this experiment has good biocompatibility within the subretinal environment and is expected to be promising in the further retinal prosthesis studies
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