Hepatitis C virus (HCV) infection is a serious cause of chronic liver disease worldwide with more than 170 million infected individuals at risk of developing significant morbidity and mortality. Current interferon-based therapies are suboptimal especially in patients infected with HCV genotype 1, and they are poorly tolerated, highlighting the unmet medical need for new therapeutics. The HCV-encoded NS3 protease is essential for viral replication and has long been considered an attractive target for therapeutic intervention in HCV-infected patients. Here we identify a class of specific and potent NS3 protease inhibitors and report the evaluation of BILN 2061, a small molecule inhibitor biologically available through oral ingestion and the first of its class in human trials. Administration of BILN 2061 to patients infected with HCV genotype 1 for 2 days resulted in an impressive reduction of HCV RNA plasma levels, and established proof-of-concept in humans for an HCV NS3 protease inhibitor. Our results further illustrate the potential of the viral-enzyme-targeted drug discovery approach for the development of new HCV therapeutics.

A given chemical may react at different rates with various soil constituents and be involved in several kinds of reactions. A combination of equilibrium and kinetic adsorption models is hypothesized to describe the nature of the overall reaction. An analytical solution to the one-dimensional convectivedispersive transport equation with a combination linear Freundlich isotherm and first-order reversible kinetic adsorption model is developed. The individual and combined effects of the model parameters on the breakthrough curves and retention profiles are examined. The combination equilibrium-kinetic model is shown to be applicable to pesticide, nutrient, and metal transport in soils.

CommunicationsPotent and selective macrocyclic inhibitors of the hepatitis C virus NS3 serine protease based on the conformation of a enzyme-bound substratelike hexapeptide demonstrate many of the desirable properties of a druglike archetype, which could lead to an antiviral agent for the treatment of hepatitis C in man. For more details see the following communication by Tsantrizos et al.

The interactions of the NS3 protease domain with inhibitors that are based on N-terminal cleavage products of peptide substrates were studied by NMR methods. Transferred nuclear Overhauser effect experiments showed that these inhibitors bind the protease in a well defined, extended conformation. Protease-induced linebroadening studies helped identify the segments of inhibitors which come into contact with the protease. A comparison of the NMR data of the free and proteasebound states suggests that these ligands undergo rigidification upon complexation. This work provides the first structure of an inhibitor when bound to NS3 protease and should be valuable for designing more potent inhibitors. Hepatitis C virus (HCV)1 infection is an important cause of chronic hepatitis, cirrhosis, hepatocellular carcinoma, and liver failure worldwide (1). Approved therapies with proven benefit for patients with chronic hepatitis C include various drug regimens of interferon-␣. These therapies have limited efficacy with a low sustained response rate and frequent side effects (1). Therefore, there is an urgent need for the development of new therapies for the treatment of HCV infections.HCV is a small enveloped virus containing a single-stranded RNA genome of positive polarity, which encodes a unique polyprotein of approximately 3000 amino acids (for reviews see Refs. 2 and 3). This polyprotein is the precursor of four structural and six nonstructural (NS) proteins (4 -10). The structural proteins are proteolytically processed by host signal peptidases, whereas two virally encoded proteases within the NS2 and NS3 regions process the remaining nonstructural proteins.The NS3 serine protease domain (20 kDa), located within the N-terminal portion of the NS3 protein, mediates the proteolysis at the NS3/4A, NS4A/4B, NS4B/5A, and NS5A/5B junctions (6 -11). We and others have recently reported that N-terminal cleavage products of peptide substrates are competitive inhibitors of NS3 protease activity (12, 13), which has served as the basis for designing substrate-based inhibitors (14, 15). To date, there have been no reports in the literature on the structure of substrates or inhibitors when bound to NS3 protease, which would certainly be valuable for inhibitor design efforts. However, x-ray crystal structures have been determined for NS3 protease alone (16) and for NS3 protease in the presence of an NS4A peptide cofactor (17,18). These structures show that NS3 protease adopts a chymotrypsin/trypsin-like fold.In this report we applied NMR methods to study the structure of peptides and inhibitors, based on N-terminal cleavage products of peptide substrates when bound to the NS3 protease domain of HCV. Transferred NOESY experiments were used to determine the conformation of ligands when bound to the protease, and differential line-broadening experiments were used to identify which segments of the ligands contact the protease. EXPERIMENTAL PROCEDURESPurification of NS3 Protease-A modification of a previously published procedure (19) was used ...

moisture use by spring wheat. TtLe accumulation of dry matter and N in whezLt (7. aestivum L. cv. Manitou) grown on stubble land in lysimeters at two moistLLre levels and seven rates of N was mt:asured and related to moisture use at five stages of developrnent. In the irrigated lyr;imeters, leaf areas, plant dry matter and N content increasedl with fertilizer N. In thr: dry lysimeters, low rainfall between the stLot blade and anthesis stages produced moisture stress; consequently, dry matter production and leaf area were depressed and plants lost significant amounts ofN at rates of N > 61.5 kg/ha. Rain in the latter part of the growing season permitted the plants to recover and by maturity plant dry matter and N content increased with N. Approximately twic,g as much plant dry matter was produced in the wet treatment as in the dry for all levels of N. Total evapotranspiration (ET) increased with applied N in the wet treatment, and was much higher than in the dry treatment (Fig. 2, top)