233 research outputs found
Increased plasma markers of oxidative stress are associated with coronary heart disease in males with diabetes mellitus and with 10-year risk in a prospective sample of males
Background: Increased oxidative stress is associated with coronary heart disease (CHD). We examined the association between plasma markers of oxidative stress and CHD in a cross-sectional sample of patients with diabetes and prospective CHD risk in a sample of men predominantly without diabetes.
Methods: Plasma total antioxidant status (TAOS) and the ratio of oxidized LDL (Ox-LDL) to LDL-cholesterol (LDL-C) were determined in a cross-section of 761 Caucasian individuals with diabetes (UDACS study). Plasma TAOS was also determined in 310 baseline samples from a 10-year prospective cohort of 3012 healthy males (NPHSII).
Results: Within UDACS, males with CHD had lower mean (SD) plasma TAOS [no CHD, 43.4 (13.2)%; CHD, 40.3 (13.8)%; P = 0.04]. The prevalence of CHD was higher in the lowest compared with the upper quartiles (32.7% vs 19.7%; P = 0.004). We observed a significant association between plasma Ox-LDL:LDL-C and CHD status [no CHD vs CHD, 16.9 (3.1) vs 19.3 (5.0) units/mmol; P = 0.04], with the prevalence of CHD being higher among men in the upper compared with lower quartiles (18.4% vs 35.1%; P = 0.003). No association was observed in females. In NPHSII, TAOS was lower in those who developed CHD [35.1 (8.0)% vs 37.1 (7.9)%; P = 0.04]. The odds ratio for CHD in the lowest compared with the upper quartile was 1.91 (95% confidence interval, 0.99–3.70; P = 0.04). This remained unchanged after adjustment for classic risk factors.
Conclusions: A cross-sectional and prospective association exists between baseline plasma measures of oxidative stress and CHD risk. The association with prospective CHD risk remained after adjustment for "traditional" risk factors, implying an independent role for oxidative stress in CHD risk
Collective T=0 pairing in N=Z nuclei? Pairing vibrations around 56Ni revisited
We present a new analysis of the pairing vibrations around 56Ni, with
emphasis on odd-odd nuclei. This analysis of the experimental excitation
energies is based on the subtraction of average properties that include the
full symmetry energy together with volume, surface and Coulomb terms. The
results clearly indicate a collective behavior of the isovector pairing
vibrations and do not support any appreciable collectivity in the isoscalar
channel.Comment: RevTeX, two-column, 5 pages, 4 figure
Hierarchical Gaussian process mixtures for regression
As a result of their good performance in practice and their desirable analytical properties, Gaussian process regression models are becoming increasingly of interest in statistics, engineering and other fields. However, two major problems arise when the model is applied to a large data-set with repeated measurements. One stems from the systematic heterogeneity among the different replications, and the other is the requirement to invert a covariance matrix which is involved in the implementation of the model. The dimension of this matrix equals the sample size of the training data-set. In this paper, a Gaussian process mixture model for regression is proposed for dealing with the above two problems, and a hybrid Markov chain Monte Carlo (MCMC) algorithm is used for its implementation. Application to a real data-set is reported
Estimation of vortex density after superconducting film quench
This paper addresses the problem of vortex formation during a rapid quench in
a superconducting film. It builds on previous work showing that in a local
gauge theory there are two distinct mechanisms of defect formation, based on
fluctuations of the scalar and gauge fields, respectively. We show how vortex
formation in a thin film differs from the fully two-dimensional case, on which
most theoretical studies have focused. We discuss ways of testing theoretical
predictions in superconductor experiments and analyse the results of recent
experiments in this light.Comment: 7 pages, no figure
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Cannabidivarin is anticonvulsant in mouse and rat in vitro and in seizure models
Summary
Background and purpose: Phytocannabinoids in Cannabis sativa have diverse
pharmacological targets extending beyond cannabinoid receptors and several exert notable
anticonvulsant effects. For the first time, we investigated the anticonvulsant profile of the
phytocannabinoid cannabidivarin (CBDV) in vitro and in in vivo seizure models.
Experimental approach: The effect of CBDV (1-100μM) on epileptiform local field
potentials (LFPs) induced in rat hippocampal brain slices by 4-AP application or Mg2+-free
conditions was assessed by in vitro multi-electrode array recordings. Additionally, the
anticonvulsant profile of CBDV (50-200 mg kg-1) in vivo was investigated in four rodent
seizure models: maximal electroshock (mES) and audiogenic seizures in mice, and
pentylenetetrazole (PTZ) and pilocarpine-induced seizures in rat. CBDV effects in
combination with commonly-used antiepileptic drugs were investigated in rat seizures.
Finally, the motor side effect profile of CBDV was investigated using static beam and gripstrength
assays.
Key results: CDBV significantly attenuated status epilepticus-like epileptiform LFPs
induced by 4-AP and Mg2+-free conditions. CBDV had significant anticonvulsant effects in
mES (≥100 mg kg-1), audiogenic (≥50 mg kg-1) and PTZ-induced seizures (≥100 mg kg-1).
CBDV alone had no effect against pilocarpine-induced seizures, but significantly attenuated
these seizures when administered with valproate or phenobarbital at 200 mg kg-1 CBDV.
CBDV had no effect on motor function.
Conclusions and Implications: These results indicate that CBDV is an effective
anticonvulsant across a broad range of seizure models, does not significantly affect normal
motor function and therefore merits further investigation in chronic epilepsy models to justify
human trials
Revisiting the critical values of the Lilliefors test: towards the correct agrometeorological use of the Kolmogorov-Smirnov framework
The Chiral Phase Transition in Dissipative Dynamics
Numerical simulations of the chiral phase transition in the (3+1)dimensional
O(4)-model are presented. The evolutions of the chiral field follow purely
dissipative dynamics, starting from random chirally symmetric initial
configurations down to the true vacuum with spontaneously broken symmetry. The
model stabilizes topological textures which are formed together with domains of
disoriented chiral condensate (DCC) during the roll-down phase. The classically
evolving field acts as source for the emission of pions and mesons.
The exponents of power laws for the growth of angular correlations and for
emission rates are extracted. Fluctuations in the abundance ratios for neutral
and charged pions are compared with those for uncorrelated sources as potential
signature for the chiral phase transition after heavy-ion collisions. It is
found that the presence of stabilizing textures (baryons and antibaryons)
prevents sufficiently rapid growth of DCC-domain size, so observability of
anomalous tails in the abundance ratios is unlikely. However, the transient
formation of growing DCC domains causes sizable broadening of the distributions
as compared to the statistical widths of generic sources.Comment: 28 pages, 8 figure
DCC Dynamics in (2+1)D-O(3) model
The dynamics of symmetry-breaking after a quench is numerically simulated on
a lattice for the (2+1)-dimensional O(3) model. In addition to the standard
sigma-model with temperature-dependent Phi^4-potential the energy functional
includes a four-derivative current-current coupling to stabilize the size of
the emerging extended topological textures. The total winding number can be
conserved by constraint. As a model for the chiral phase transition during the
cooling phase after a hadronic collision this allows to investigate the
interference of 'baryon-antibaryon' production with the developing disoriented
aligned domains. The growth of angular correlations, condensate, average
orientation is studied in dependence of texture size, quench rate, symmetry
breaking. The classical dissipative dynamics determines the rate of energy
emitted from the relaxing source for each component of the 3-vector field which
provides a possible signature for domains of Disoriented Chiral Condensate. We
find that the 'pions' are emitted in two distinct pulses; for sufficiently
small lattice size the second one carries the DCC signal, but it is strongly
suppressed as compared to simultaneous 'sigma'-meson emission. We compare the
resulting anomalies in the distributions of DCC pions with probabilities
derived within the commonly used coherent state formalism.Comment: 27 pages, 17 figures; several minor insertions in the text; two
references adde
Auxiliary subunit regulation of high-voltage activated calcium channels expressed in mammalian cells
The effects of auxiliary calcium channel subunits on the expression and functional properties of high-voltage activated (HVA) calcium channels have been studied extensively in the Xenopus oocyte expression system, but are less completely characterized in a mammalian cellular environment. Here, we provide the first systematic analysis of the effects of calcium channel beta and alpha(2)-delta subunits on expression levels and biophysical properties of three different types (Ca(v)1.2, Ca(v)2.1 and Ca(v)2.3) of HVA calcium channels expressed in tsA-201 cells. Our data show that Ca(v)1.2 and Ca(v)2.3 channels yield significant barium current in the absence of any auxiliary subunits. Although calcium channel beta subunits were in principle capable of increasing whole cell conductance, this effect was dependent on the type of calcium channel alpha(1) subunit, and beta(3) subunits altogether failed to enhance current amplitude irrespective of channel subtype. Moreover, the alpha(2)-delta subunit alone is capable of increasing current amplitude of each channel type examined, and at least for members of the Ca(v)2 channel family, appears to act synergistically with beta subunits. In general agreement with previous studies, channel activation and inactivation gating was regulated both by beta and by alpha(2)-delta subunits. However, whereas pronounced regulation of inactivation characteristics was seen with the majority of the auxiliary subunits, effects on voltage dependence of activation were only small (< 5 mV). Overall, through a systematic approach, we have elucidated a previously underestimated role of the alpha(2)-delta(1) subunit with regard to current enhancement and kinetics. Moreover, the effects of each auxiliary subunit on whole cell conductance and channel gating appear to be specifically tailored to subsets of calcium channel subtypes
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