Construction and characterization of efficient, stable and safe replication-deficient foamy virus vectors

As serious side effects affected recent virus-mediated gene transfer studies, novel vectors with improved safety profiles are urgently needed. In the present study, replication-deficient retroviral vectors based on feline foamy virus (FFV) were constructed and analyzed. The novel FFV vectors are devoid of almost the complete env gene plus the internal promoter - accessory bel gene cassette including the gene for the viral transcriptional transactivator Bel1/Tas. In these Bel1/Tas-independent vectors, expression of the lacZ (beta-galactosidase) marker gene is directed by the heterologous, constitutively active human ubiquitin C promoter (ubi). Env-transcomplemented vectors have un-concentrated titers of more than 10(5) transducing units/ml. The vectors allow efficient transduction of a broad array of diverse target cells, which can be increased by repeated vector exposure. However, the number of lacZ marker gene expressing cells decreased slightly upon serial passages of the transduced cells. Vectors carrying a self-inactivating (SIN) deletion of the TATA box and most parts of the viral promoter were not rescued by wt FFV whereas those with the intact or a partially deleted promoter were readily reactivated. This finding indicates that the viral promoters are in fact non-functional, pointing to a highly advantageous safety profile of these new FFV-ubi-lacZ-SIN vectors.

Serum concentrations of salicylate and naproxen during concurrent therapy in patients with rheumatoid arthritis

The kinetic interaction between salicylate and naproxen was investigated in 25 rheumatoid arthritis patients. Kinetic interactions were tested in serum after patients had been on each drug regimen for 1 month. Salicylate decreased serum naproxen concentration from 89.5 mg/liter to 65.9 mg/liter (P less than 0.001) and increased serum naproxen clearance by 56%. Naproxen had minimal effect on serum salicylate concentrations.

A strategy for reaching therapeutic salicylate levels in patients with rheumatoid arthritis using standardized dosing regimens

After one to 2 weeks of 45 mg/kg/day choline magnesium trisalicylate (CMT) in 2 divided doses, 51 of 71 patients with rheumatoid arthritis (72%) had observed steady state serum salicylate concentrations between 150 and 300 mg/l (mean salicylate: 213 +/- 10 mg/l), although 17 later required dose adjustment. CMT dosing was changed in 37 cases by using the formula: dosing rate = total clearance X concentration. The expected and observed concentrations were not different (p = 0.31); thus, this formula can help calculate salicylate dosing changes to bring the serum salicylate level to within the therapeutic range.

A controlled study of concurrent therapy with a nonacetylated salicylate and naproxen in rheumatoid arthritis

Previous studies of combinations of nonsteroidal drugs used in the treatment of rheumatoid arthritis (RA) have yielded conflicting results. We used standard methods to measure disease activity and high pressure liquid chromatography to measure plasma drug concentrations. We used doses of choline magnesium trisalicylate, adjusted to achieve therapeutic serum salicylate concentrations, and naproxen in a randomized, double-blind, placebo-controlled cross-over study of full dose trisalicylate (CMT), full dose naproxen (N), full dose of both (CMT-N), and half dose of both (cmt-n) to examine their relative efficacy and toxicity in treating RA. CMT-N was statistically superior to all other treatments in only 1 of 12 efficacy variables, but was equal to N and better than CMT or cmt-n for 7 variables. There were minimal differences among treatments for the other 4 efficacy variables. The mean percentage difference for the efficacy variables between CMT-N and N was 3%, between CMT-N and CMT was 10.6%, and between CMT-N and cmt-n was 10.5%. Thirteen percent of patients manifested toxic reactions during the initial open dose-adjustment salicylate run-in phase. During the double-blind phases of the study, CMT-N was more toxic than N, CMT, or cmt-n (7.5% versus 3.4%, 1.8%, and 3.7%, respectively). Tinnitus was more common when full-dose CMT was used; N (N or CMT-N) was associated with increased skin toxicity. Gastrointestinal complaints were equally common with all regimens. CMT-N, although sometimes statistically superior to CMT, N, or cmt-n, showed no clinically important additive or synergistic effect versus N or CMT alone.