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Biomedical subjects

H A Carlson

Publications and source records attributed to H A Carlson.

5 recordsLinked to original sources
PubMed2002

A randomized trial of divalproex sodium extended-release tablets in migraine prophylaxis.

OBJECTIVE: To evaluate the efficacy and safety of extended-release divalproex sodium compared with placebo in prophylactic monotherapy treatment of migraine headache. METHODS: This was a double-blind, randomized, placebo-controlled, parallel-group study. Subjects with more than two migraine headache attacks during a 4-week baseline were randomly assigned in a 1:1 ratio at each center to receive either extended-release divalproex sodium or matching placebo once daily for 12 weeks. Subjects initiated treatment on 500 mg once daily for 1 week, and the dose was then increased to 1,000 mg once daily with an option, if intolerance occurred, to permanently decrease the dose to 500 mg during the second week. Reduction from baseline in 4-week migraine headache rate was the primary efficacy variable. Migraine headaches separated by a < 24-hour headache-free interval were counted as single migraines in calculating migraine headache rates. Tolerance and safety were also evaluated. RESULTS: The mean reductions in 4-week migraine headache rate were 1.2 (from a baseline mean of 4.4) in the extended-release divalproex sodium group and 0.6 (from a baseline mean of 4.2) in the placebo group (p = 0.006); reductions with extended-release divalproex sodium were significantly greater than with placebo in all three 4-week segments of the treatment period. No significant differences were detected between treatment groups in either the overall incidence or in the incidence of any specific treatment-emergent adverse event; 8% of subjects treated with extended-release divalproex sodium and 9% of those treated with placebo discontinued for adverse events. CONCLUSION: Extended-release divalproex sodium is an efficacious, well-tolerated, safe, and easy-to-use once-a-day prophylactic antimigraine medication.

Adolescent↗
PubMed2000

Developing a dynamic pharmacophore model for HIV-1 integrase.

We present the first receptor-based pharmacophore model for HIV-1 integrase. The development of "dynamic" pharmacophore models is a new method that accounts for the inherent flexibility of the active site and aims to reduce the entropic penalties associated with binding a ligand. Furthermore, this new drug discovery method overcomes the limitation of an incomplete crystal structure of the target protein. A molecular dynamics (MD) simulation describes the flexibility of the uncomplexed protein. Many conformational models of the protein are saved from the MD simulations and used in a series of multi-unit search for interacting conformers (MUSIC) simulations. MUSIC is a multiple-copy minimization method, available in the BOSS program; it is used to determine binding regions for probe molecules containing functional groups that complement the active site. All protein conformations from the MD are overlaid, and conserved binding regions for the probe molecules are identified. Those conserved binding regions define the dynamic pharmacophore model. Here, the dynamic model is compared to known inhibitors of the integrase as well as a three-point, ligand-based pharmacophore model from the literature. Also, a "static" pharmacophore model was determined in the standard fashion, using a single crystal structure. Inhibitors thought to bind in the active site of HIV-1 integrase fit the dynamic model but not the static model. Finally, we have identified a set of compounds from the Available Chemicals Directory that fit the dynamic pharmacophore model, and experimental testing of the compounds has confirmed several new inhibitors.

Computer Simulation↗
PubMed1999

Calculation of the pKa values for the ligands and side chains of Escherichia coli D-alanine:D-alanine ligase.

Poisson-Boltzmann electrostatics methods have been used to calculate the pKa shifts for the ligands and titratable side chains of D-alanine:D-alanine ligase of the ddlb gene of Escherichia coli (DdlB). The focus of this study is to determine the ionization state of the second D-alanine (D-Ala2) in the active site of DdlB. The pKa of the amine is shifted over 5 pKa units more alkaline in the protein, clearly implying that D-Ala2 is bound to DdlB in its zwitterionic state and not in the free-base form as had been previously suggested. Comparisons are made to the depsipeptide ligase from the vancomycin-resistance cascade, VanA. It is suggested that VanA has different enzymatic properties due to a change in binding specificity rather than altered catalytic behavior and that the specificity of binding D-lactate over D-Ala2 may arise from the difference in ionization characteristics of the ligands.

Binding Sites↗
PubMed1999

Molecular dynamics studies on the HIV-1 integrase catalytic domain.

The HIV-1 integrase, which is essential for viral replication, catalyzes the insertion of viral DNA into the host chromosome, thereby recruiting host cell machinery into making viral proteins. It represents the third main HIV enzyme target for inhibitor design, the first two being the reverse transcriptase and the protease. Two 1-ns molecular dynamics simulations have been carried out on completely hydrated models of the HIV-1 integrase catalytic domain, one with no metal ions and another with one magnesium ion in the catalytic site. The simulations predict that the region of the active site that is missing in the published crystal structures has (at the time of this work) more secondary structure than previously thought. The flexibility of this region has been discussed with respect to the mechanistic function of the enzyme. The results of these simulations will be used as part of inhibitor design projects directed against the catalytic domain of the enzyme.

Amino Acid Sequence↗