Regulatory mechanism of heat-active retrotransposons by the SET domain protein SUVH2.

New transposon insertions are deleterious to genome stability. The RNA-directed DNA methylation (RdDM) pathway evolved to regulate transposon activity via DNA methylation. However, current studies have not yet clearly described the transposition regulation. ONSEN is a heat-activated retrotransposon that is activated at 37°C. The plant-specific SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG (SUVH) family proteins function downstream of the RdDM pathway. The SUVH protein families are linked to TE silencing by two pathways, one through DNA methylation and the other through chromatin remodeling. In this study, we analyzed the regulation of ONSEN activity by SUVH2. We observed that ONSEN transcripts were increased; however, there was no transpositional activity in Arabidopsis suvh2 mutant. The suvh2 mutant produced siRNAs from the ONSEN locus under heat stress, suggesting that siRNAs are involved in suppressing transposition. These results provide new insights into the regulatory mechanisms of retrotransposons that involve siRNA in the RdDM pathway.

Effects of abatacept in patients with methotrexate-resistant active rheumatoid arthritis: a randomized trial.

BACKGROUND: The selective co-stimulation modulator abatacept demonstrated efficacy for treating rheumatoid arthritis in early clinical studies. OBJECTIVE: To evaluate the effects of abatacept in patients with persistent, active rheumatoid arthritis despite methotrexate treatment. DESIGN: One-year, multicenter, randomized, double-blind, placebo-controlled trial (November 2002 to October 2004). SETTING: 116 centers worldwide. PATIENTS: 652 patients with active rheumatoid arthritis despite methotrexate treatment. INTERVENTION: Once-monthly infusion of a fixed dose of abatacept, approximately 10 mg/kg of body weight, or placebo. MEASUREMENTS: Co-primary end points were a 20% improvement in American College of Rheumatology (ACR) response criteria (ACR 20) at 6 months, clinically meaningful improvements in physical function, and change from baseline in joint erosion score at 1 year. RESULTS: Four hundred thirty-three and 219 patients were randomly assigned to abatacept or placebo, respectively, and 385 (89%) and 162 (74%), respectively, completed 1 year of treatment. In a modified intention-to-treat analysis, 6-month ACR 20, ACR 50, and ACR 70 responses were 67.9% for abatacept versus 39.7% for placebo (difference, 28.2 percentage points [95% CI, 19.8 to 36.7 percentage points]), 39.9% for abatacept versus 16.8% for placebo (difference, 23.0 percentage points [CI, 15.0 to 31.1 percentage points]), and 19.8% for abatacept versus 6.5% for placebo (difference, 13.3 percentage points [CI, 7.0 to 19.5 percentage points]), respectively. At 1 year, the responses increased to 73.1% for abatacept versus 39.7% for placebo (difference, 33.4 percentage points [CI, 25.1 to 41.7 percentage points]), 48.3% for abatacept versus 18.2% for placebo (difference, 30.1 percentage points [CI, 21.8 to 38.5 percentage points]), and 28.8% for abatacept versus 6.1% for placebo (difference, 22.7 percentage points [CI, 15.6 to 29.8 percentage points]), respectively (P < 0.001 for all). Physical function significantly improved in 63.7% versus 39.3% of patients (P < 0.001). At 1 year, abatacept statistically significantly slowed the progression of structural joint damage compared with placebo. Abatacept-treated patients had a similar incidence of adverse events (87.3% vs. 84.0%; difference, 3.3 percentage points [CI, -2.5 to 9.1 percentage points]) and a higher incidence of prespecified serious infections (2.5% vs. 0.9%; difference, 1.6 percentage points [CI, -0.3 to 3.6 percentage points]) and infusion reactions (acute, 8.8% vs. 4.1%; difference, 4.7 percentage points [CI, 0.9 to 8.4 percentage points]; peri-infusional, 24.5% vs. 16.9%; difference, 7.6 percentage points [CI, 1.2 to 14.0 percentage points]) compared with placebo recipients. LIMITATIONS: The study involved only 1 group of patients over 1 year. CONCLUSIONS: Abatacept statistically significantly reduced disease activity in patients with rheumatoid arthritis and an inadequate response to methotrexate. Longer treatment in different patient populations is needed to establish its appropriate role in rheumatoid arthritis.

Effect of a high-fat meal on the pharmacokinetics of the des-F(6)-quinolone BMS-284756.

STUDY OBJECTIVE: To evaluate the effects of a high-fat meal on the systemic exposure of oral BMS-284756. DESIGN: Open-label, randomized, two-way crossover study. SETTING: Clinical research facility. SUBJECTS: Fourteen healthy individuals. INTERVENTIONS: Participants received two single 400-mg doses of BMS-284756, separated by at least 1 week. One dose was given while participants were fasting, and one dose was given within 5 minutes of consumption of a high-fat meal. MEASUREMENTS AND MAIN RESULTS: Serial blood samples were collected, and plasma samples were analyzed for BMS-284756 using a validated liquid chromatography with tandem mass spectrometry detection method. Maximum plasma concentration and area under the plasma concentration-time curve (AUC) after the high-fat meal were 19% and 11% lower, respectively, than those in the fasted state. The 90% confidence intervals for the ratios of means (0.71-0.94 and 0.85-0.93, respectively) satisfied predefined equivalence criteria. Equivalence of the AUC values for BMS-284756 in fed and fasted individuals indicates that the presence of food should not affect the efficacy of this drug. CONCLUSION: Single doses of BMS-284756 were safe and well tolerated and may be taken without regard to meals.