343 research outputs found
Multidimensional protein fractionation using ProteomeLab PF 2D™ for profiling amyotrophic lateral sclerosis immunity: A preliminary report
Background: The ProteomeLab™ PF 2D platform is a relatively new approach to global protein profiling. Herein, it was used for investigation of plasma proteome changes in amyotrophic lateral sclerosis (ALS) patients before and during immunization with glatiramer acetate (GA) in a clinical trial. Results: The experimental design included immunoaffinity depletion of 12 most abundant proteins from plasma samples with the ProteomeLab™ IgY-12 LC10 column kit as first dimension separation, also referred to as immuno-partitioning. Second and third dimension separations of the enriched proteome were performed on the PF 2D platform utilizing 2D isoelectric focusing and RP-HPLC with the resulting fractions collected for analysis. 1D gel electrophoresis was added as a fourth dimension when sufficient protein was available. Protein identification from collected fractions was performed using nano-LC-MS/MS approach. Analysis of differences in the resulting two-dimensional maps of fractions obtained from the PF 2D and the ability to identify proteins from these fractions allowed sensitivity threshold measurements. Masked proteins in the PF 2D fractions are discussed. Conclusion: We offer some insight into the strengths and limitations of this emerging proteomic platform
Multiple genome-wide analyses of smoking behavior in the Framingham Heart Study
BACKGROUND: Cigarette smoking behavior may have a genetic basis. We assessed evidence for quantitative trait loci (QTLs) affecting the maximum number of cigarettes smoked per day, a trait meant to quantify this behavior, using data collected over 40 years as part of the Framingham Heart Study's original and offspring cohorts. RESULTS: Heritability was estimated to be approximately 21% using variance components (VC) methods (SOLAR), while oligogenic linkage and segregation analysis based on Bayesian Markov chain Monte Carlo (MCMC) methods (LOKI) estimated a mean of two large QTLs contributing approximately 28% and 20%, respectively, to the trait's variance. Genome-wide parametric (FASTLINK) and VC linkage analyses (SOLAR) revealed several LOD scores greater than 1.0, with peak LOD scores using both methods on chromosomes 2, 17, and 20; multi-point MCMC methods followed up on these chromosomes. The most robust linkage results were for a QTL between 65 and 84 cM on chromosome 20 with signals from multiple sex- and age-adjusted analyses including two-point LOD scores of 1.30 (parametric) and 1.07 (heritability = 0.17, VC) at 70.51 cM, a multi-point LOD score of 1.50 (heritability = 0.20, VC) at 84 cM, and an intensity ratio of 12.0 (MCMC) at 65 cM. CONCLUSION: Familial aggregation of the maximum number of cigarettes smoked per day was consistent with a genetic component to this behavior, and oligogenic segregation analyses using MCMC suggested two important QTLs. Linkage signals on chromosome 20 between 65 and 84 cM were seen using multiple analytical methods. No linkage result, however, met genome-wide statistical significance criteria, and the true relationship between these regions and smoking behavior remains unclear
General thoughts to the Kaon pair production in the threshold region
Simple--minded thoughts about the cross sections for the reactions
pp-->ppK+K- and pp-->ppK0K0 are presented, which certainly do not account for
the complex coupled channel problem but rather provide some ideas into the
mutual reaction dynamics.Comment: Talk given at 9th International Workshop on Meson Production,
Properties and Interaction, Cracow, Poland, 9-13 June 2006. 3 pages, 2
figure
Eta and eta' mesons production at COSY-11
The low emittance and small momentum spread of the proton and deuteron beams
of the Cooler Synchrotron COSY combined with the high mass resolution of the
COSY-11 detection system permit to study the creation of mesons in the
nucleon-nucleon interaction down to the fraction of MeV with respect to the
kinematical threshold. At such small excess energies, the ejectiles possess low
relative momenta and are predominantly produced with the relative angular
momentum equal to zero. Taking advantage of these conditions we have performed
investigations aiming to determine the mechanism of the production of eta and
eta' mesons in the collision of hadrons as well as the hadronic interaction of
these mesons with nucleons and nuclei. In this proceedings we address the
ongoing studies of the spin and isospin dependence for the production of the
eta and eta' mesons in free and quasi-free nucleon-nucleon collisions. New
results on the spin observables for the vec(p)p --> pp eta reaction, combined
with the previously determined total cross section isospin dependence, reveal a
statistically significant indication that the excitation of the nucleon to the
S11(1535) resonance, the process which intermediates the production of the eta
meson in the nucleon-nucleon interactions, is predominantly due to the exchange
of the pi meson between the colliding nucleons.Comment: Invited talk at MESON 2006: 9th International Workshop on Meson
Production, Properties and Interactions, Cracow, Poland, 9-13 Jun 200
Hadronic interaction of eta and eta-prime mesons with nucleons
Due to their short life-time, flavour-neutral mesons cannot be utilized as
free secondary beams or targets, and therefore a study of their interaction
with nucleons is not possible via direct scattering experiments.
This interaction is, however, accessible via its influence on the energy
dependence - and on the phase space distributions of the cross sections for
reactions in which these mesons are produced.
In case of the p p --> p p eta reaction the experimentally determined
distributions of the differential cross sections close to the production
threshold cannot be described by taking into account the S-wave proton-proton
and proton-eta interaction only. Here we show that the angular distributions
determined at the COSY-11 facility reveal some evidence for P-wave admixture in
the proton-proton subsystem already at an excess energy as low as Q = 15.5 MeV.
We also present that one can estimate the relative strength of the
eta-nucleon and eta-prime-nucleon interactions by comparison of the eta and
eta-prime production yield.Comment: 4 pages, 3 figures, Talk given at 16th International Conference on
Particles and Nuclei (PANIC 02), Osaka, Japan, 30 Sep - 4 Oct 200
Study of the 3He-eta system in d-p collisions at COSY-11
We present preliminary results from dp --> 3He X (X=pi0,eta) measurements
near the eta production threshold. The data were taken during a slow ramping of
the COSY internal deuteron beam scattered on a proton target. The 3He ejectiles
were registered with the COSY-11 detection setup. The ongoing data analysis
should deliver high precision data for the dp --> 3He eta total and
differential cross sections for the excess energies in the range from threshold
up to 9 MeV. The preliminary excitation function for the reaction dp --> 3He
pi0 does not show any structure which could originate from the decay of 3He-eta
bound state. We present also a threshold excitation curve for the dp --> 3He X
channel. Contrary to corresponding results from SATURNE we see no cusp in the
vicinity of the eta threshold.Comment: 8 pages; 5 figures; Talk at Eta05 Workshop on Production and Decay of
eta and eta-prime Mesons, Cracow, Poland, 15-18 Sep 2005; Acta Phys. Slovaca,
in prin
COSY-11: an experimental facility for studying meson production in free and quasi-free nucleon-nucleon collisions
The COSY-11 experimental setup is an internal facility installed at the
COoler SYnchrotron COSY in Juelich. It allows to investigate meson production
in free and quasi-free nucleon-nucleon collisions, eg. pp --> pp meson and pd
--> p_sp np meson reactions. Drift chambers and scintillators permit to measure
outgoing protons, separated in magnetic field of COSY-11 dipole. Neutrons are
registered in the neutron modular detector installed downstream the beam.
Recently, the experimental setup has been extended with spectator detector,
deuteron drift chamber and polarization monitoring system, and since then meson
production can be investigated also as a function of spin and isospin of
colliding nucleons.Comment: Presented at LEAP05: International conference on Low Energy
Antiproton Physics, Bonn - Juelich, Germany, May 16-22, 200
Isospin dependence of the eta' meson production in nucleon--nucleon collisions
According to the quark model, the masses of eta and eta' mesons should be
almost equal. However, the empirical values of these masses differ by more than
the factor of two. Similarly, though the almost the same quark-antiquark
content, the total cross section for the creation of these mesons close to the
kinematical thresholds in the pp --> ppX reaction differs significantly. Using
the COSY-11 detection setup we intend to determine whether this difference will
also be so significant in the case of the production of these mesons in the
proton-neutron scattering. Additionally, the comparison of the pp --> pp eta'
and pn --> pn eta' total cross sections will allow to learn about the
production of the eta' meson in the channels of isospin I = 0 and I = 1 and to
investigate aspects of the gluonium component of the eta' meson.Comment: Presented at LEAP05: International conference on Low Energy
Antiproton Physics, Bonn - Juelich, Germany, May 16-22, 200
Experimental study of the eta-meson interaction with two-nucleons
By means of the COSY-11 detection system, using a stochastically cooled
proton beam of the cooler synchrotron COSY and a hydrogen cluster target, we
have performed a high statistics measurement of the pp --> pp eta reaction at
an excess energy of Q = 15.5 MeV.
The experiment was based on the four-momentum determination of both outgoing
protons. This permits to identify pp --> pp eta events and to derive the
complete kinematical information of the eta-p-p-system allowing for subsequent
investigations of the eta-p interaction.
The observed spectrum of the invariant mass of the proton-proton system
deviates strongly from the phase-space distribution revealing the influence of
the final-state-interaction among the outgoing particles or nontrivial features
of the primary production mechanism.Comment: 6 pages, 4 figures, Talk presented at Meson 2002, 7th International
Workshop on Meson Production, Properties and Interaction, Cracow, Poland,
24-28 May 200
- …