807 research outputs found
Sequestration of Muscarinic Cholinergic Receptors in Permeabilized Neuroblastoma Cells
The feasibility of using a permeabilized preparation of human SH-SY-5Y neuroblastoma cells for studies of muscarinic acetylcholine receptor (mAChR) sequestration has been evaluated. Exposure of cells permeabilized with digitonin, streptolysin-O, or the Α-toxin from Staphylococcus aureus to oxotremorine-M (Oxo-M) for 30 min resulted in a 25–30% reduction in the number of cell surface mAChRs, as monitored by the loss of N [ 3 H]methyl- scopolamine ([ 3 H]NMS) binding sites. The corresponding value for intact cells was 40%. For cells permeabilized with 20 Μ M digitonin, the Oxo-M-mediated reduction in [ 3 H]NMS binding was time ( t 1/2 ∼ 5 min) and concentration (EC 50 ∼ 10 Μ M ) dependent and was agonist specific (Oxo M > bethanechol = arecoline = pilocarpine). In contrast, no reduction in total mAChR number, as monitored by the binding of [ 3 H]quinuclidinyl benzilate, occurred following Oxo-M treatment. The loss of [ 3 H]NMS sites observed in the presence of Oxo-M was unaffected by omission of either ATP or Ca 2+ , both of which are required for stimulated phosphoinositide hydrolysis, but could be inhibited by the inclusion of guanosine 5′- O -(2-thiodiphosphate). mAChRs sequestered in response to Oxo-M addition were unmasked when the cells were permeabilized in the presence of higher concentrations of digitonin (80 Μ M ). The results indicate (a) that permeabilized SH-SY-5Y cells support an agonist-induced sequestration of mAChRs, the magnitude of which is ∼ 65–70% of that observed for intact cells, (b) that when internalized, mAChRs are located in a cellular compartment to which [ 3 H]NMS has only a limited access despite the removal of the plasma membrane barrier, and (c) that the production of phosphoinositide-derived second messengers is not a prerequisite for mAChR sequestration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65736/1/j.1471-4159.1994.62051795.x.pd
Ground-Water Quality in Kentucky: Fluoride
Fluoride (F-) is an ion of the element fluorine, and is a natural component in most water resources. According to Hem (1989), fluoride concentrations in fresh water are generally less than 1 mg/L (milligrams per liter), and the concentration of fluoride in the world\u27s oceans is about 1.3 mg/L. The source of most fluoride in natural fresh-water resources is various rocks and minerals in bedrock and sediments
Domain Growth in a 1-D Driven Diffusive System
The low-temperature coarsening dynamics of a one-dimensional Ising model,
with conserved magnetisation and subject to a small external driving force, is
studied analytically in the limit where the volume fraction \mu of the minority
phase is small, and numerically for general \mu. The mean domain size L(t)
grows as t^{1/2} in all cases, and the domain-size distribution for domains of
one sign is very well described by the form P_l(l) \propto
(l/L^3)\exp[-\lambda(\mu)(l^2/L^2)], which is exact for small \mu (and possibly
for all \mu). The persistence exponent for the minority phase has the value 3/2
for \mu \to 0.Comment: 8 pages, REVTeX, 7 Postscript figures, uses multicol.sty and
epsf.sty. Submitted to Phys. Rev.
The adaptive immune and immune checkpoint landscape of neoadjuvant treated esophageal adenocarcinoma using digital pathology quantitation
Acknowledgments The samples used in this research were received from the Northern Ireland Biobank, which has ethical approval to use de-identified tissue samples from the Belfast Health and Social Care Tissue Pathology archive (REC:11/NI/0013). The Northern Ireland Molecular Pathology Laboratory, was responsible for construction of tissue microarrays, slide staining, and scanning. We are grateful to the NVIDIA Corporation for supporting our research via the GPU Grant Program for researchers. The research leading to these results has also received funding from Invest Northern Ireland. The authors thank Mr. Ken Arthur for the construction of the original tissue microarrays used in this study. Funding This study was funded by a CRUK Accelerator Grant (A20256) to JJ and MST. CRUK had no role in the study design, collection, analysis, and interpretation of the data or in the writing of the report.Peer reviewedPublisher PD
Coherence in the Quasi-Particle 'Scattering' by the Vortex Lattice in Pure Type-II Superconductors
The effect of quasi-particle (QP) 'scattering' by the vortex lattice on the
de-Haas van-Alphen oscillations in a pure type-II superconductor is
investigated within mean field,asymptotic perturbation theory. Using a 2D
electron gas model it is shown that, due to a strict phase coherence in the
many-particle correlation functions, the 'scattering' effect in the asymptotic
limit () is much weaker than what is predicted
by the random vortex lattice model proposed by Maki and Stephen, which destroys
this coherence . The coherent many particle configuration is a collinear array
of many particle coordinates, localized within a spatial region with size of
the order of the magnetic length. The amplitude of the magnetization
oscillations is sharply damped just below because of strong
out of phase magnetic oscillations in the superconducting
condensation energy ,which tend to cancel the normal electron oscillations.
Within the ideal 2D model used it is found, however, that because of the
relative smallness of the quartic and higher order terms in the expansion, the
oscillations amplitude at lower fields does not really damp to zero, but only
reverses sign and remains virtually undamped well below . This
conclusion may be changed if disorder in the vortex lattice, or vortex lines
motion will be taken into account. The reduced QP 'scattering' effect may be
responsible for the apparent crossover from a strong damping of the dHvA
oscillations just below to a weaker damping at lower fields observed
experimentally in several 3D superconductors.Comment: 26 pages, Revtex no Figure
Algebraic Self-Similar Renormalization in Theory of Critical Phenomena
We consider the method of self-similar renormalization for calculating
critical temperatures and critical indices. A new optimized variant of the
method for an effective summation of asymptotic series is suggested and
illustrated by several different examples. The advantage of the method is in
combining simplicity with high accuracy.Comment: 1 file, 44 pages, RevTe
The Current-Temperature Phase Diagram of Layered Superconductors
The behavior of clean layered superconductors in the presence of a finite
electric current and in zero-magnetic field behavior is addressed. The
structure of the current temperature phase diagram and the properties of each
of the four regions will be explained. We will discuss the expected current
voltage and resistance characteristics of each region as well as the effects of
finite size and weak disorder on the phase diagram. In addition, the reason for
which a weakly non-ohmic region exists above the transition temperature will be
explained.Comment: 8 pages (RevTeX), 4 encapsulated postscript figure
Differentiation and fiber type-specific activity of a muscle creatine kinase intronic enhancer
Background:
Hundreds of genes, including muscle creatine kinase (MCK), are differentially expressed in fast- and slow-twitch muscle fibers, but the fiber type-specific regulatory mechanisms are not well understood.
Results:
Modulatory region 1 (MR1) is a 1-kb regulatory region within MCK intron 1 that is highly active in terminally differentiating skeletal myocytes in vitro. A MCK small intronic enhancer (MCK-SIE) containing a paired E-box/myocyte enhancer factor 2 (MEF2) regulatory motif resides within MR1. The SIE's transcriptional activity equals that of the extensively characterized 206-bp MCK 5'-enhancer, but the MCK-SIE is flanked by regions that can repress its activity via the individual and combined effects of about 15 different but highly conserved 9- to 24-bp sequences. ChIP and ChIP-Seq analyses indicate that the SIE and the MCK 5'-enhancer are occupied by MyoD, myogenin and MEF2. Many other E-boxes located within or immediately adjacent to intron 1 are not occupied by MyoD or myogenin. Transgenic analysis of a 6.5-kb MCK genomic fragment containing the 5'-enhancer and proximal promoter plus the 3.2-kb intron 1, with and without MR1, indicates that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers (types I and IIa, respectively), but is not required for expression in fast-twitch muscle fibers (types IIb and IId).
Conclusions:
In this study, we discovered that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers and that MR1's positive transcriptional activity depends on a paired E-box MEF2 site motif within a SIE. This is the first study to delineate the DNA controls for MCK expression in different skeletal muscle fiber types
Noisy random resistor networks: renormalized field theory for the multifractal moments of the current distribution
We study the multifractal moments of the current distribution in randomly
diluted resistor networks near the percolation treshold. When an external
current is applied between to terminals and of the network, the
th multifractal moment scales as , where is the correlation length exponent of
the isotropic percolation universality class. By applying our concept of master
operators [Europhys. Lett. {\bf 51}, 539 (2000)] we calculate the family of
multifractal exponents for to two-loop order. We find
that our result is in good agreement with numerical data for three dimensions.Comment: 30 pages, 6 figure
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