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Rheumatoid arthritis (RA) is the prototype of the rheumatic diseases worldwide. Methotrexate (MTX) is the drug of first choice in the treatment of this disease due to its immunosuppressant effect. However, side events are present in 30% of the patients. The C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are involved in the metabolism of MTX. Earlier studies reported an association between these polymorphisms and elevation of hepatic enzymes. We analyzed the frequencies of both polymorphisms and the presence of transaminasemia in 70 Mexican patients with rheumatic arthritis treated with MTX. The 19% (13/70) of patients had an increase in the serum level of transaminases. The A1298C polymorphism was associated with elevation of transaminases (P=0.024). The identification of MTHFR genotypes for C677T and A1298C polymorphisms could lead clinicians to identify patients in risk of elevation of transaminases, and give them an individualized treatment, as is a goal of pharmacogenetics. [ABSTRACT FROM AUTHOR]

We applied the free-energy perturbation method together with the averaged solvent electrostatic potential from molecular dynamics (ASEP/MD) method to study the anomeric equilibrium of d-xylose in aqueous solution. The level of calculation, 6-311G++(2d,2p) basis set and density functional theory, permits one to explain the main characteristics of the anomeric equilibrium of d-xylopyranose: in vacuo, the anomeric effect predominates and the α form is the stabler. In water, solvation leads to the β form being the stabler. A comparison between the performances of the ASEP/MD and polarizable continuum models is also presented. [ABSTRACT FROM AUTHOR]