543 research outputs found
Rebamipide Does Not Protect Against Naproxen-induced Gastric Damage: A Randomized Double-blind Controlled Trial
Rebamipide is a gastroprotective agent with promising results against gastric damage induced by non-steroidal anti-inflammatory drugs. The present study evaluated if rebamipide protects against naproxen-induced gastric damage in healthy volunteers. Changes in gastric PGE2 tissue concentration were also evaluated. Methods: After a preliminary endoscopy to rule out previous gastric macroscopic damage, twenty-four healthy volunteers of both sexes were divided into 2 groups. One group received sodium naproxen 550 mg b.i.d. plus placebo for 7 days, while the other group received sodium naproxen 550 mg b.i.d. plus rebamipide 100 mg b.i.d. At the end of treatment, a new endoscopy was performed. Gastric macroscopic damage was evaluated by the Cryer score and by the modified Lanza score. The primary outcome measure of the trial was the macroscopic damage observed in each treatment group at the end of treatment. Biopsies were collected at both endoscopies for PGE2 quantification and histopathological analysis (secondary outcomes). Tissue PGE2 was quantified by ELISA. The randomization sequence was generated using 3 blocks of 8 subjects each. Volunteers and endoscopists were blind to whether they were receiving rebamipide or placebo. Results: All recruited volunteers completed the trial. Sodium naproxen induced gastric damage in both groups. At the end of the study, median Cryer score was 4 in both groups (Difference = 0; 95% CI = -1 to 0; p = 0.728). In the placebo group, the mean tissue PGE2 concentration was 1005 +/- 129 pg/mL before treatment and 241 +/- 41 pg/mL after treatment (p < 0.001). In the rebamipide group, the mean tissue PGE2 concentration was 999 +/- 109 pg/mL before treatment, and 168 +/- 13 pg/mL after treatment (p < 0.001). There was no difference in mean tissue PGE2 between the two groups (difference = 5; 95% CI from -334.870 to 345.650; p = 0.975). No significant change was observed at the histopathological evaluation, despite the evident macroscopic damage induced by naproxen. Conclusion: Rebamipide does not protect against naproxen-induced gastric damage in healthy volunteers.16Biolab Industria Farmaceutica Ltd
Charge-density waves in one-dimensional Hubbard superlattices
We study the formation of charge density waves (CDW's) in one-dimensional
Hubbard superlattices, modeled by a repeated pattern of repulsive (U>0) and
free (U=0) sites. By means of Lanczos diagonalizations for the ground state, we
calculate the charge structure factor. Our results show that while the
superlattice structure affects the modulation of the charge density waves, the
periodicity can still be predicted through an effective density. We also show
that, for a fixed repulsive layer thickness, the periodicity of the CDW is an
oscillatory function of the free layer thickness.Comment: 4 pages, 4 figure
Primary Intravascular Synovial Sarcoma of the Femoral Vein in a Male Patient, Case Report
AbstractSynovial Sarcoma (SS) is an aggressive neoplasm commonly affecting deep soft tissues of the extremities. In rare instances SS can arise in large veins of the lower extremities or trunk. We report the first case of intravascular synovial sarcoma (IVSS) occurring in a male patient. A biphasic tumor was diagnosed by histology and immunohistochemistry. Molecular analysis at RNA level confirmed the diagnosis demonstrating the chromosomal translocation t(X;18) (p11.2;q11.2) in the tumor. Although extremely rare, IVSS should be considered in the differential diagnosis of primary intravascular neoplasms and as a potential cause of deep vein thrombosis and thromboembolism
Recursion Method in Quantum Spin Dynamics: The Art of Terminating a Continued Fraction
The results obtained from applications of the recursion method to quantum many‐body dynamics can be greatly improved if an appropriate termination function is employed in the continued‐fraction representation of the corresponding relaxation function. We present a general recipe for the construction and use of such termination functions along with two applications in spin dynamics. The method can be adapted to any other problem in quantum many‐body dynamics
Drude Weight of the Two-Dimensional Hubbard Model -- Reexamination of Finite-Size Effect in Exact Diagonalization Study --
The Drude weight of the Hubbard model on the two-dimensional square lattice
is studied by the exact diagonalizations applied to clusters up to 20 sites. We
carefully examine finite-size effects by consideration of the appropriate
shapes of clusters and the appropriate boundary condition beyond the imitation
of employing only the simple periodic boundary condition. We successfully
capture the behavior of the Drude weight that is proportional to the squared
hole doping concentration. Our present result gives a consistent understanding
of the transition between the Mott insulator and doped metals. We also find, in
the frequency dependence of the optical conductivity, that the mid-gap
incoherent part emerges more quickly than the coherent part and rather
insensitive to the doping concentration in accordance with the scaling of the
Drude weight.Comment: 9 pages with 10 figures and 1 table. accepted in J. Phys. Soc. Jp
Charge and spin excitations of insulating lamellar copper oxides
A consistent description of low-energy charge and spin responses of the
insulating Sr_2CuO_2Cl_2 lamellar system is found in the framework of a
one-band Hubbard model which besides includes hoppings up to 3^{rd}
nearest-neighbors. By combining mean-field calculations, exact diagonalization
(ED) results, and Quantum Monte Carlo simulations (QMC), we analyze both charge
and spin degrees of freedom responses as observed by optical conductivity,
ARPES, Raman and inelastic neutron scattering experiments. Within this
effective model, long-range hopping processes flatten the quasiparticle band
around . We calculate also the non-resonant A_{1g} and B_{1g} Raman
profiles and show that the latter is composed by two main features, which are
attributed to 2- and 4-magnon scattering.Comment: 6 pages, 3 figures, To be published in PRB (july
Low-Energy Structure of Heisenberg Ferrimagnetic Spin Chains
Static and dynamic structure factors of Heisenberg ferrimagnetic spin chains
are numerically investigated. There exist two distinct branches of elementary
excitations, which exhibit ferromagnetic and antiferromagnetic aspects. The
ferromagnetic feature is smeared out with the increase of temperature, whereas
the antiferromagnetic one persists up to higher temperatures. The scattering
intensity is remarkably large at lower boundaries of the ferromagnetic and
antiferromagnetic spectra. All these observations are consistent with the
ferromagnetic-to-antiferromagnetic crossover in the thermal behavior which has
recently been reported.Comment: 3 pages, 5 PS figures, to appear in J. Phys. Soc. Jpn. Vol. 67, No.
11 (1998
Parallelization of the exact diagonalization of the t-t'-Hubbard model
We present a new parallel algorithm for the exact diagonalization of the
-Hubbard model with the Lanczos-method. By invoking a new scheme of
labeling the states we were able to obtain a speedup of up to four on 16 nodes
of an IBM SP2 for the calculation of the ground state energy and an almost
linear speedup for the calculation of the correlation functions. Using this
algorithm we performed an extensive study of the influence of the next-nearest
hopping parameter in the -Hubbard model on ground state energy and
the superconducting correlation functions for both attractive and repulsive
interaction.Comment: 18 Pages, 1 table, 8 figures, Latex uses revtex, submitted to Comp.
Phys. Com
Direct Calculation of the Spin Stiffness in the -- Heisenberg Antiferromagnet
We calculate the spin stiffness for the frustrated
spin- Heisenberg antiferromagnet on a square lattice by exact
diagonalizations on finite clusters of up to sites followed by
extrapolations to the thermodynamic limit. For the non-frustrated case, we find
that , in excellent agreement with the best
results obtained by other means. Turning on frustration, the extrapolated
stiffness vanishes for . In this
intermediate region, the finite-size scaling works poorly -- an additional sign
that their is neither N\'eel nor collinear magnetic order. Using a hydrodynamic
relation, and previous results for the transverse susceptibility, we also
estimate the spin-wave velocity in the N\'eel-ordered region.Comment: 4 pages, uuencoded compressed ps-file (made with uufiles
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