The steep, high‐relief eastern margin of the Tibetan Plateau has undergone rapid Cenozoic cooling and denudation yet shows little evidence for large‐magnitude shortening or accommodation generation in the foreland basin. We address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin. The Beichuan and Pengguan faults are active, dominantly dextral‐slip structures that can be traced continuously for up to 200 km along the plateau margin. Both faults offset fluvial fill terraces that yield inheritance‐corrected, cosmogenic 10Be exposure ages of <15 kyr, indicating latest Pleistocene activity. The Pengguan fault appears to have been active in the Holocene at two sites along strike. Latest Quaternary apparent throw rates on both faults are variable along strike but are typically <1 mm yr−1. Rates of strike‐slip displacement are likely to be several times higher, probably ∼1–10 mm yr−1 but remain poorly constrained. Late Quaternary folding and dextral strike‐slip has also occurred along the western margin of the Sichuan Basin, particularly associated with the present‐day mountain front. These observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening. They also suggest that activity on the margin‐parallel faults in eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin.

Human rhinoviruses, the most important etiologic agents of the common cold, are messenger-active single-stranded monocistronic RNA viruses that have evolved a highly complex cascade of proteolytic processing events to control viral gene expression and replication. Most maturation cleavages within the precursor polyprotein are mediated by rhinovirus 3C protease (or its immediate precursor, 3CD), a cysteine protease with a trypsin-like polypeptide fold. Highresolution crystal structures of the enzyme from three viral serotypes have been used for the design and elaboration of 3C protease inhibitors representing different structural and chemical classes. Inhibitors having ␣,␤-unsaturated carbonyl groups combined with peptidyl-binding elements specific for 3C protease undergo a Michael reaction mediated by nucleophilic addition of the enzyme's catalytic Cys-147, resulting in covalent-bond formation and irreversible inactivation of the viral protease. Direct inhibition of 3C proteolytic activity in virally infected cells treated with these compounds can be inferred from dose-dependent accumulations of viral precursor polyproteins as determined by SDS͞PAGE analysis of radiolabeled proteins. Cocrystal-structure-assisted optimization of 3C-protease-directed Michael acceptors has yielded molecules having extremely rapid in vitro inactivation of the viral protease, potent antiviral activity against multiple rhinovirus serotypes and low cellular toxicity. Recently, one compound in this series, AG7088, has entered clinical trials.

Experimental autoimmune uveitis (EAU) serves as a model for human autoimmune uveitis and for cell-mediated autoimmunity in general. EAU induced in mice by immunization with the retinal Ag interphotoreceptor retinoid-binding protein in CFA is driven by the Th17 response. Oral calcitriol (1,25-dihydroxyvitamin D3) prevented as well as partly reversed disease and suppressed immunological responses. In vitro, calcitriol directly suppressed IL-17 induction in purified naive CD4+ T cells without inhibiting Th17 lineage commitment, as reflected by unaltered RORγt, STAT3, and FoxP3 expression. In contrast, in vivo treatment with calcitriol of mice challenged for EAU impaired commitment to the Th17 lineage, as judged by reduction of both RORγt and IL-17 in CD4+ T cells. Innate immune response parameters in draining lymph nodes of treated mice were suppressed, as was production of IL-1, IL-6, TNF-α, and IL-12/IL-23p40, but not IL-10, by explanted splenic dendritic cells (DC). Finally, supernatants of calcitriol-conditioned bone marrow-derived DC had reduced ability to support Th17 polarization of naive CD4+ T cells in vitro and in vivo. Thus, calcitriol appears to suppress autoimmunity by inhibiting the Th17 response at several levels, including the ability of DC to support priming of Th17 cells, the ability of CD4+ T cells to commit to the Th17 lineage, and the ability of committed Th17 T cells to produce IL-17.

The structure-based design, chemical synthesis, and biological evaluation of various human rhinovirus (HRV) 3C protease (3CP) inhibitors which incorporate P1 lactam moieties in lieu of an L-glutamine residue are described. These compounds are comprised of a tripeptidyl or peptidomimetic binding determinant and an ethyl propenoate Michael acceptor moiety which forms an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme. The P1-lactam-containing inhibitors display significantly increased 3CP inhibition activity along with improved antirhinoviral properties relative to corresponding L-glutamine-derived molecules. In addition, several lactam-containing compounds exhibit excellent selectivity for HRV 3CP over several other serine and cysteine proteases and are not appreciably degraded by a variety of biological agents. One of the most potent inhibitors (AG7088, mean antirhinoviral EC90 approximately 0.10 microM, n = 46 serotypes) is shown to warrant additional preclinical development to explore its potential for use as an antirhinoviral agent.

The eye attempts to limit local immune and inflammatory responses to preserve vision. This phenomenon, known as ocular immune privilege, is mediated by a combination of local and systemic mechanisms. While immune privilege is believed to protect the eye from day-to-day inflammatory insults, it is not absolute and its mechanisms are still incompletely understood.

AG7088 is a potent, irreversible inhibitor of human rhinovirus (HRV) 3C protease {inactivation rate constant (k obs /[I]} ‫؍‬ 1,470,000 ؎ 440,000 M ؊1 s ؊1 for HRV 14) that was discovered by protein structure-based drug design methodologies. In H1-HeLa and MRC-5 cell protection assays, AG7088 inhibited the replication of all HRV serotypes (48 of 48) tested with a mean 50% effective concentration (EC 50 ) of 0.023 M (range, 0.003 to 0.081 M) and a mean EC 90 of 0.082 M (range, 0.018 to 0.261 M) as well as that of related picornaviruses including coxsackieviruses A21 and B3, enterovirus 70, and echovirus 11. No significant reductions in the antiviral activity of AG7088 were observed when assays were performed in the presence of ␣ 1 -acid glycoprotein or mucin, proteins present in nasal secretions. The 50% cytotoxic concentration of AG7088 was >1,000 M, yielding a therapeutic index of >12,346 to >333,333. In a single-cycle, time-of-addition assay, AG7088 demonstrated antiviral activity when added up to 6 h after infection. In contrast, a compound targeting viral attachment and/or uncoating was effective only when added at the initiation of virus infection. Direct inhibition of 3C proteolytic activity in infected cells treated with AG7088 was demonstrated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis analysis of radiolabeled proteins, which showed a dose-dependent accumulation of viral precursor polyproteins and reduction of processed protein products. The broad spectrum of antiviral activity of AG7088, combined with its efficacy even when added late in the virus life cycle, highlights the advantages of 3C protease as a target and suggests that AG7088 will be a promising clinical candidate. MATERIALS AND METHODSCompounds. AG7088 and pleconaril (17) were synthesized at Agouron Pharmaceuticals, Inc. Pirodavir (1) was kindly provided by Janssen Research Foundation (Beerse, Belgium), and WIN 51711 (40) was kindly provided by Sterling Winthrop Research Institute (Collegeville, Pa.). Ganciclovir (Syntex Corp., Palo Alto, Calif.) was obtained from a local pharmacy, and acyclovir was purchased from Sigma (St. Louis, Mo.).Cells and virus strains. All numbered HRV serotypes, echovirus type 11 (EV 11), enterovirus type 70 (ETV 70), coxsackievirus types A21 (CAV 21) and B3 strain Nancy (CVB 3), human cytomegalovirus (HCMV) strain AD169, and herpes simplex virus type 1 (HSV-1) strain McIntyre were purchased from the American Type Culture Collection (ATCC; Manassas, Va.). HRV Hanks and a nasal lavage from a patient challenged with HRV Hanks were kindly provided by Ronald Turner from the Medical University of South Carolina, Charleston, S.C. HRV and coxsackievirus stocks were propagated, and antiviral assays were performed, in H1-HeLa cells (ATCC) incubated at 34 and 37°C, respectively. ETV 70, EV 11, and HCMV stocks were propagated, and antiviral assays were performed, in MRC-5 (ATCC) cells at 37°C. HSV-1 stocks were propagated, and antiviral assays were performed, in Vero (ATCC) cells incubated at 37°C. Vero cells ...

The structure-based design, chemical synthesis, and biological evaluation of peptide-derived human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds incorporate various Michael acceptor moieties and are shown to irreversibly bind to HRV serotype 14 3CP with inhibition activities (kobs/[I]) ranging from 100 to 600 000 M-1 s-1. These inhibitors are also shown to exhibit antiviral activity when tested against HRV-14-infected H1-HeLa cells with EC50's approaching 0.50 microM. Extensive structure-activity relationships developed by Michael acceptor alteration are reported along with the evaluation of several compounds against HRV serotypes other than 14. A 2.0 A crystal structure of a peptide-derived inhibitor complexed with HRV-2 3CP is also detailed.

The structure-based design, chemical synthesis, and biological evaluation of various 2-pyridone-containing human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds are comprised of a peptidomimetic binding determinant and a Michael acceptor moiety, which forms an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme. The 2-pyridone-containing inhibitors typically display improved 3CP inhibition properties relative to related peptide-derived molecules along with more favorable antiviral properties. The cocrystal structure of one pyridone-derived 3CP inhibitor complexed with HRV-2 3CP is also described along with certain ab initio conformation analyses. Optimization of the 2-pyridone-containing compounds is shown to provide several highly active 3CP inhibitors (k(obs)/[I] > 500,00 M(-1) s(-1)) that function as potent antirhinoviral agents (EC(50) = <0.05 microM) against multiple virus serotypes in cell culture. One 2-pyridone-containing 3CP inhibitor is shown to be bioavailable in the dog after oral dosing (F = 48%).