Aptamers are double-stranded DNA or single-stranded RNA molecules that bind specific molecular targets. Large randomly generated populations can be enriched in aptamers by in vitro selection and polymerase chain reaction. But so far single-stranded DNA has not been investigated for aptamer properties, nor has a target protein been considered that does not interact physiologically with nucleic acid. Here we describe the isolation of single-stranded DNA aptamers to the protease thrombin of the blood coagulation cascade and report binding affinities in the range 25-200 nM. Sequence data from 32 thrombin aptamers, selected from a pool of DNA containing 60 nucleotides of random sequence, displayed a highly conserved 14-17-base region. Several of these aptamers at nanomolar concentrations inhibited thrombin-catalysed fibrin-clot formation in vitro using either purified fibrinogen or human plasma.

753 patients infected with HIV who were antiretroviral naive were screened and 602 patients entered the study. Intervention Patients were randomized to receive either tenofovir DF (n=299) or stavudine (n=303), with placebo, in combination with lamivudine and efavirenz. Main Outcome Measure Proportion of patients with HIV RNA levels of less than 400 copies/mL at week 48. Results In the primary intent-to-treat analysis in which patients with missing data or who added or switched antiretroviral medications before week 48 were considered as failures, the proportion of patients with HIV RNA of less than 400 copies/mL at week 48 was 239 (80%) of 299 in patients receiving tenofovir DF and 253 (84%) of 301 in patients receiving stavudine (95% confidence interval, −10.4% to 1.5%), exceeding the predefined −10% limit for equivalence. However, equivalence was demonstrated in the secondary analyses (HIV RNA Ͻ50 copies/ mL) at week 48 and through 144 weeks. Virologic failure was associated most frequently with efavirenz and lamivudine resistance. Through 144 weeks, the K65R mutation emerged in 8 and 2 patients in the tenofovir DF and stavudine groups, respectively (P = .06). A more favorable mean change from baseline in fasting lipid profile was noted in the tenofovir DF group at week 144: for triglyceride levels (+1 mg/dL for tenofovir DF [n=170] vs +134 mg/dL for stavudine [n=162], PϽ.001), total cholesterol (+30 mg/dL [n=170] vs +58 mg/dL [n=162], PϽ.001), direct lowdensity lipoprotein cholesterol (+14 mg/dL [n = 169] vs +26 mg/dL [n = 161], PϽ.001), and high-density lipoprotein cholesterol (+9 mg/dL [n=168] vs +6 mg/dL [n = 154], P = .003). Investigator-reported lipodystrophy was less common in the tenofovir DF group compared with the stavudine group (9 [3%] of 299 vs 58 [19%] of 301, PϽ.001). The number of bone fractures and the renal safety profile were similar between the 2 groups. Conclusions Through 144 weeks, the combination of tenofovir DF, lamivudine, and efavirenz was highly effective and comparable with stavudine, lamivudine, and efavirenz in antiretroviral-naive patients. However, tenofovir DF appeared to be associated with better lipid profiles and less lipodystrophy.

Molecules involved in the antigen receptor-dependent regulation of early T cell activation genes were investigated with the use of functional sequences of the T cell activation-specific enhancer of interleukin-2 (IL-2). One of these sequences forms a protein complex, NFAT-1, specifically with nuclear extracts of activated T cells. This complex appeared 10 to 25 minutes before the activation of the IL-2 gene. Studies with inhibitors of protein synthesis indicated that the time of synthesis of the activator of the IL-2 gene in Jurkat T cells corresponds to the time of appearance of NFAT-1. NFAT-1, or a very similar protein, bound functional sequences of the long terminal repeat (LTR) of the human immunodeficiency virus type 1; the LTR of this virus is known to be stimulated during early T cell activation. The binding site for this complex activated a linked promoter after transfection into antigen receptor-activated T cells but not other cell types. These characteristics suggest that NFAT-1 transmits signals initiated at the T cell antigen receptor.

Through week 48, the combination of tenofovir DF and emtricitabine plus efavirenz fulfilled the criteria for noninferiority to a fixed dose of zidovudine and lamivudine plus efavirenz and proved superior in terms of virologic suppression, CD4 response, and adverse events resulting in discontinuation of the study drugs. (ClinicalTrials.gov number, NCT00112047.)