#236 - Co-sponsored Sessions

ACS National Meeting
Fall, 2008
Philadelphia, PA



COMP - Targeting Protein Kinases in Drug Design
1:30 46 Designing kinase inhibitor prototypes
Vikki M. Tsefrikas, vikki.tsefrikas@astrazeneca.com, Les Dakin, les.dakin@astrazeneca.com, Tony Cheung, Geri Bebernitz, Joseph Gozgit, and Claudio Chuaqui, Claudio.Chuaqui@astrazeneca.com. AstraZeneca R&D Boston, Waltham, MA 02451

Irreversible inhibition of protein kinases is emerging as an important strategy to achieve non-ATP competitive blockade of kinase mediated signaling. Because of their mode of action, irreversible inhibitors also offer distinct advantages to standard non-covalent ATP-site binders. Inhibitor potency is dependent on two factors: initial molecular recognition followed by a slow alkylation step where a covalent bond is formed to a free Cys in proximity to the inhibitor. Consequently, only kinases with available Cys residues in a suitable binding site can be targeted, thus affording greater control over the selectivity profile of the inhibitor. In addition to enhanced selectivity, irreversible inhibitors have emerged as a strategy to circumvent acquired resistance arising from mutations that reduce drug binding. We have applied a general strategy for the structure based design of irreversible kinase inhibitors that involves a structural bioinformatics analysis to identify kinases with accessible Cys residues in the ATP binding, ligand docking of suitable kinase specific scaffolds, and the incorporation of an alkylating group to target specific Cys residues. The design, characterization and properties for several example kinases will be discussed.

2:05 47 The DFG motif as a central conformational switch controlling drug binding
Yibing Shan, shan@deshaw.com1, Markus A. Seeliger2, Michael P. Eastwood1, Filipp Frank2, Huafeng Xu1, Morten Ø. Jensen1, Ron O. Dror1, John Kuriyan2, and David E. Shaw1. (1) D. E. Shaw Research, 120 West 45th Street, New York, NY 10036, (2) University of California, Berkeley, CA 94720

In many protein kinases, a characteristic conformational change (the “DFG flip”) connects catalytically active and inactive conformations. Many kinase inhibitors—including the cancer drug imatinib—selectively target a specific DFG conformation, but the function and mechanism of the flip remain unclear. Using long molecular dynamics simulations of the Abl kinase, we visualized the DFG flip in atomic-level detail and formulated an energetic model predicting that the local electrostatics in the ATP-binding site controls the flip. Our model was experimentally validated using the imatinib binding to the kinase domain of c-Abl as a conformational probe of the DFG-out conformation. Our model suggests that the DFG motif may be conserved in part because the DFG flip allows the kinase to access flexible conformations facilitating nucleotide binding and release, thus facilitating the process of protein kinase catalysis. The set of intermediate conformations observed in our simulations of the DFG flip may present new opportunities for kinase inhibitor design.

2:40 Intermission
2:55 48 Surveying ligand- and target-based similarities within the Kinome
Stephan C. Schurer, Kevin Hambly, Joseph Danzer, and Steven M Muskal, smuskal@eidogen-sertanty.com. Eidogen-Sertanty, Inc, 3460 Marron St #103-475, Oceanside, CA 92056

Several investigators have studied similarities and differences within the protein kinase complement of the human genome (the "kinome") from both sequence and ligand-based perspectives. We present a novel analysis of the human kinome using receptor-site similarity. Having clustered kinase domains by ATP binding-site similarity, we can identify kinases that may be selectively targetable as well as those that can be readily grouped and targeted together. We believe the same approach can be applied to the entire structure-resolvable/modelable proteome, allowing receptor-site information from entire target families to be used in the rational design of compounds with desirable selectivity profiles.

3:30 49 Structure based design of irreversible kinase inhibitors
Vikki M. Tsefrikas, vikki.tsefrikas@astrazeneca.com, Les Dakin, les.dakin@astrazeneca.com, Tony Cheung, Geri Bebernitz, Joseph Gozgit, and Claudio Chuaqui, Claudio.Chuaqui@astrazeneca.com. AstraZeneca R&D Boston, Waltham, MA 02451

Irreversible inhibition of protein kinases is emerging as an important strategy to achieve non-ATP competitive blockade of kinase mediated signaling. Because of their mode of action, irreversible inhibitors also offer distinct advantages to standard non-covalent ATP-site binders. Inhibitor potency is dependent on two factors: initial molecular recognition followed by a slow alkylation step where a covalent bond is formed to a free Cys in proximity to the inhibitor. Consequently, only kinases with available Cys residues in a suitable binding site can be targeted, thus affording greater control over the selectivity profile of the inhibitor. In addition to enhanced selectivity, irreversible inhibitors have emerged as a strategy to circumvent acquired resistance arising from mutations that reduce drug binding. We have applied a general strategy for the structure based design of irreversible kinase inhibitors that involves a structural bioinformatics analysis to identify kinases with accessible Cys residues in the ATP binding, ligand docking of suitable kinase specific scaffolds, and the incorporation of an alkylating group to target specific Cys residues. The design, characterization and properties for several example kinases will be discussed.

SUNDAY MORNING

COMP - Pharmacology: The Forgotten Art of Drug Discovery
Sofitel Hotel Versailles
Tudor I. Oprea, Organizer
8:00 27 Estrogen receptors as therapeutic targets in breast cancer
Eric A. Ariazi, Eric.Ariazi@fccc.edu and V. Craig Jordan, V.Craig.Jordan@fccc.edu. Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19422

The estrogen receptor α (ERα) has proven to be the single most important target in breast cancer. The use of the selective ER modulator (SERM) tamoxifen for the treatment and prevention of breast cancer has changed therapeutics. The study of tamoxifen metabolism has provided insights to aid structure function analysis, to understand tamoxifen-mediated rat liver carcinogenesis, and to identify tamoxifen's active metabolites. The SERM raloxifene, approved for treating osteoporosis, lacks tamoxifen's increased risk for endometrial cancer and is now used for the prevention of breast cancer in postmenopausal women. The antagonistic properties of tamoxifen and raloxifene are a result of their antiestrogenic side chains protruding from the ligand binding pocket, thereby preventing the receptor's helix 12 in the major transcriptional activation region AF-2 from sealing the pocket, and instead it occupies the coactivator recognition groove preventing coactivator recruitment. The agonist properties of these SERMs are likely due in part to their protruding antiestrogenic side chains recognizing Asp-351 on the surface of the receptor, which then participates in an occult transactivation function region AF-2b that allosterically interacts with ER's minor transactivation function region AF-1. Other SERMs include clomiphene, toremifene, idoxifene, droloxifene, ospemifene, GW5638, GW7604, lasofoxifene, levormeloxifene, CHF 4227, EM-800, acolbifene, arzoxifene, bazedoxifene, and HMR 3339. The pure antiestrogen fulvestrant is effective as a second line therapy following tamoxifen failure. The pure antiestrogen ICI 164,384 takes on an inverted conformation allowing the 7α-substituted side chain to exit the ligand binding pocket similarly to SERMs. The pure antiestrogen's side chain bends back towards the receptor's surface interacting at the coactivator recognition site and preventing helix 12 from doing so. Thus, pure antiestrogens induce an abnormal receptor structure that is in turn hyperubiquinated and shuttled to the proteasome for degradation. Additional pure antiestrogens under development include ZK-703, ZK-253, RU 58668, and TAS-108.

8:30 28 Localization, distribution, and pharmacology of G protein-coupled estrogen receptor GPR30
Eugen Brailoiu, ebrailou@temple.edu1, G. Cristina Brailoiu, gbrailou@temple.edu1, Siok Le Dun, sldun@temple.edu1, Elena Deliu, elenadeliu@gmail.com1, Eric A. Ariazi, Eric.Ariazi@fccc.edu2, Jeffrey B. Arterburn, jarterbu@nmsu.edu3, Eric R. Prossnitz, eprossnitz@salud.unm.edu4, Tudor I. Oprea, toprea@salud.unm.edu5, V. Craig Jordan, V.Craig.Jordan@fccc.edu2, and Nae J. Dun, ndun@temple.edu1. (1) Department of Pharmacology, Temple University School of Medicine, 3420 N. Broad Street, Philadelphia, PA 19140, (2) Fox Chase Cancer Center, Philadelphia, PA 19422, (3) Department of Chemistry and Biochemistry MSC 3C, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, (4) Department of Cell Biology and Physiology, University of New Mexico, 915 Camino de Salud, N.E, Albuquerque, NM 87131-5041, (5) Health Sciences Center, University of New Mexico, University of New Mexico, Albuquerque, NM 87131-0001

GPR30 has been identified as a G protein-coupled estrogen receptor distinct from the nuclear estrogen receptors ERa and ERb. Using intracellular injection vs. extracellular administration, and imaging techniques, we studied the effect of GPR30 ligands on rat central neurons, SKBR3 breast cancer cells, and human aortic endothelial cells (HAEC) in vitro. G-1, a selective GPR30 agonist, increased cytosolic Ca2+ concentrations [Ca2+]i in rat central neurons. Intracellular injection of 17-b-estradiol (E2) or G-1 into SKBR3 cells evoked a rapid and robust increase of [Ca2+]i, which was attenuated by siRNA knock down of GPR30 expression. Extracellular administration of E2 or G-1 caused a small increase of [Ca2+]i. These observations demonstrated that functional GPR30 was primarily localized to the cytoplasm of SKBR3 cells. In HAEC, which express GPR30, G-1 and E2 mobilized calcium and hyperpolarized the membrane. G-1 was about 15-fold more effective than E2. Using an animal model of depression, G-1 or E2 administered to mice reduced the immobility time in the tail suspension test. Our result indicates that G-1 is a GPR30 selective agonist and supports a role of GPR30 in estrogen-mediated cellular and behavioral responses.

9:00 29 Opioid agonist-selective signaling
Ping Y. Law, lawxx001@umn.edu, Department of Pharmacology, School of Medicine, University of Minnesota, 6-120 Jackson Hall, 321 Church St. S.E, Minneapolis, MN 55455

In the drug discovery process, the cellular location of the drug targets such as receptor is critical for the eventual efficacy of the drugs. Using opioid receptor and agonist activation of ERK phosphorylation as a model, we could demonstrate agonist-selective signaling. Such agonist-dependent signaling arises from the ability of various opioid agonists to induce the receptor to translocate from the lipid raft domains on plasma membrane, where the signaling molecules are clustered. The translocation of the receptor from the microdomains also affected the signals that the receptor could transduce, and also the consequence of the signal transduction, i.e., genes transcriptions. Thus, the ability of individual agonist to promote the drug target translocation will dictate the signals being transduced and subsequently the eventual cellular responses.

9:30 30 HTS and pharmacology of multiplexed small GTPase targets by flow cytometry
Larry A Sklar, lsklar@salud.unm.edu1, Zurab Surviladze, ZSurviladze@salud.unm.edu1, Gary M. Bokoch, bokoch@scripps.edu2, Cristian G. Bologa1, Bruce Edwards, BEdwards@salud.unm.edu1, Tudor I. Oprea, toprea@salud.unm.edu1, Oleg Ursu, OUrsu@salud.unm.edu1, Anna Waller, AWaller@salud.unm.edu1, Hui Zhang2, and Angela Wandinger-Ness, AWandinger@salud.unm.edu1. (1) Health Sciences Center, University of New Mexico, 1 University of New Mexico, Cancer Research Facility 200A, Albuquerque, NM 87131, (2) The Scripps Research Institute, La Jolla, CA 92037

We are multiplexing targets for HTS using the multi-parameter optical capabilities of the flow cytometer. Multiplexing is achieved with families of targets that are color-coded as suspension arrays. Several multiplexes have been screened against the NIH small molecule repository, a compound library of over 200,000 small molecules. We have screened a sixplex comprising small GTPases and a fluorescent GTP analog. One of the major advantages of multiplexing is that selectivity can be observed in the primary screen. The GTPase family screens reveal both activators and inhibitors. Among both classes of molecules are molecules with intracellular activities. Molecular insight into the mechanisms of action has been provided in a variety of novel assays including direct measures of GTPase activation, nucleotide exchange, and regulation of intracellular pathways in cell models of inflammatory response. Future opportunities for small molecule discovery include the development of HTS multiplexes that probe protein-protein interactions, such as those involving small GTPases and their regulatory partners.

10:00   Intermission
10:10 31 Mechanisms of allostery and membrane attachment in Ras GTPases
Alemayehu A. Gorfe, abebe@mccammon.ucsd.edu, Department of Chemistry and Biochemistry and Center for Theoretical Biological Physics, University of California,San Diego, 9500 Gilman Drive, La Jolla, CA 92093, Barry J. Grant, bgrant@mccammon.ucsd.edu, Chemistry and Biochemistry and Center for Theoretical Biological Physics, University of California at San Diego, 9500 Gilman Drive, La jolla, CA 92093-0365, and J Andrew McCammon, jmccammon@ucsd.edu, Howard Hughes Medical Institute, Department of Chemistry and Biochemistry and Department of Pharmacology, Center for Theoretical Biological Physics, University of California at San Diego, 9500 Gilman Drive, Mail Code 0365, La Jolla, CA 92093-0365

Ras GTPases are membrane anchored signaling mediators that control cell division and development. Despite their prominent role in many forms of cancer, the mechanism and thermodynamics of membrane insertion, the structure of the membrane bound Ras, and the allosteric modulation of lateral segregation by the catalytic domain remained elusive. Here, we establish the structural and dynamic link between the conserved active site switch regions and the membrane interacting C-terminal hypervariable region. We employed a variety of computational techniques, including classical and accelerated molecular dynamics simulations, structural bioinformatics, potential of mean force calculations, and other methods for the estimation of membrane insertion free energies. We will show that, upon GDP/GTP exchange, a coordinated network of interactions communicates information from switches I and II through a newly identified switch III to the membrane surface. The resulting differential interaction of the catalytic domain and/or the linker with membrane surfaces causes variations in the insertion depth and localized structural perturbation to the host lipid bilayer. We will discuss these findings in connection with previous and new collaborative experimental results.

10:40 32 Virtual screening provides a mechanism for finding a chemical tool from a biological messenger
Grant Churchill, grant.churchill@pharm.ox.ac.uk, Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom

Historically, a primary means of probing the biological role of any given protein was with small molecules. Currently, this pharmacological approach has been surpassed by genetic techniques (knock-in, knock-out and small inhibitory RNA). Nevertheless, small molecules have the advantage that protein function can be altered in a rapid, selective, reversible and dose-dependent manner. Research into the biological role of the calcium-releasing second messenger NAADP (nicotinic acid adenine dinucleotide phosphate) has been hampered by the lack of chemical tools. An attractive solution is to evaluate millions of molecules with virtual screening. We used a ligand-based virtual screen to progress from NAADP to an antagonist (Ned-14), which is potent at nanomolar concentrations, structurally unrelated to NAADP, cell permeant and fluorescent. Therefore, Ned-14 blocks NAADP signaling and labels NAADP receptors in intact cells. We conclude that virtual screening is now accessible, powerful and a largely untapped source of chemical tools.

11:10 33 Perspectives and learnings on in silico pharmacology and biological fingerprints
Jonathan S. Mason, drugdesign@email.com, Computational Chemistry & Structural Biology, Lundbeck Research, Ottiliavej 9, Valby, DK-2500 Copenhagen, Denmark

Major challenges in the drug discovery process include the identification of new/relevant disease targets, the identification of tool and lead compounds for these targets and the selection of a development candidate that is differentiated from any other compounds with attrition risk minimised, or at least orthogonalized for multiple candidates. Major initiatives to systematically generate (e.g. Cerep BioPrint) and integrate (e.g. WOMBAT/GAUDI project & Pfizer “DrugStore” based on curated published data from Inpharmatica/BioFocusDPI StARLITe, BioPrint & in-house data)bioactivity data have enabled many new learnings and perspectives on drug-drug, drug-target, drug-antitarget, drug-property and target-target relationships and the analysis of concepts of molecular similarity vs biological similarity. These will be discussed, together with the use of relevant in silico chracterizations of ligands and protein targets (e.g. GRID-based FLAP pharmacophore fingerprints).

11:40 34 Using a network pharmacology approach to better understand adverse drug reactions
Josef Scheiber, josef.scheiber@novartis.com, Jeremy L. Jenkins, jeremy.jenkins@novartis.com, Dmitri Mikhailov, dmitri.mikhailov@novartis.com, Sai Chetan K. Sukuru, chetan.sukuru@novartis.com, Steven Whitebread, Jacques Hamon, Laszlo Urban, Kamal Azzaoui, Meir Glick, meir.glick@novartis.com, and John W. Davies. Lead Finding Platform, Novartis Institutes for BioMedical Research, 250 Massachusetts Avenue, Cambridge, MA 02139

Despite regulatory vigilance, unwanted toxicity and other especially adverse drug reactions (ADRs) of widely-used drugs remain a major public health concern. To avoid such cases and thereby improve the quality of life of patients it is without question highly desirable to identify and eliminate molecules with such anticipated problems during early phases of drug discovery.

In some cases the reason for an undesired effect can be found in the interaction of the compound with a certain target. These cases can then be identified by well-established in vitro-methods by determining the affinity to the target. Also, newly developed in silico-methods recognizing similar molecule structures can be used. However, often chemically diverse compounds cause similar problems. In some cases it happens when the compounds modulate two (or more) different targets in the same biological pathway. For this scenario, models solely based on compound-adverse event pairings can be established that predict certain adverse effects irrespective of target considerations. After computing these models a link through chemical space can be made to compute correlations with different target prediction models.2 Thereby it becomes possible to link certain phenotypic effects to the interaction between a molecule and a target.

To gain better pharmacological confidence in the predictions we introduced biological network information to establish firm links between side effects and the interference of a compound with a certain pathway. This way, the predictions can be validated by analyzing the data contained in well-known pathway tools and databases like GeneGo's MetaCore and Ingenuitys' IPA. In addition, new links between pathways and side effects can be established.

To summarize: The presentation will link Systems Chemical Biology approaches to the field of adverse side effects of drugs to better understand them in a pharmacological context..

SUNDAY AFTERNOON

MEDI - New Frontiers in Drug Delivery
Pennsylvania Convention Center 204 A&B
Jeff Zablocki, Organizer
1:30 25 Injectables for prevention of pain and peritoneal adhesions
Daniel S Kohane, daniel.kohane@childrens.harvard.edu, Anesthesiology/Critical Care Medicine, Children's Hospital Boston, Harvard Medical School, Bader 628, 300 Longwood Ave., Boston, MA 02466

Biomaterials and delivery technologies have come to play major roles in the delivery of drugs to a variety of anatomical locations. Here we will address issues in delivery to peripheral nerve and the peritoneum. Due to the broad extent of the research in these topics, we will be restricted to covering themes that are broadly applicable with emphasis on design criteria, major challenges, what has been done, and lessons learned, rather than a detailed review of the field.

2:00 26 Drug eluting stent technology
Josiah N. Wilcox, cy.wilcox@medtronic.com, Dept. Science & Technology, Medtronic CardioVascular, 3576 Unocal Place, Santa Rosa, CA 95403

Drug eluting stents (DES) are widely used in an effort to reduce the incidence of restenosis and target lesion revascularization after coronary artery stenting. There are four components of a DES including the stent, the balloon catheter delivery system, the drug and a polymer that binds the drug to the stent and/or controls its release in a timed fashion. The most important considerations relative to successful development of a DES are the choice of drug, the kinetics of drug release and the polymeric coating. This presentation will discuss the relative advantages of slow and fast release DES drug formulations as well as the importance of polymer biocompatibility on long term safety and efficacy of DES.

2:30 27 Systemic delivery of RNA interference for metabolic and oncology targets
Muthiah Manoharan, mmanoharan@alnylam.com, Department of Drug Discovery, Alnylam Pharmaceuticals Inc, 300 Third Street, Cambridge, MA 02142

RNA interference (RNAi) is a powerful biological process for specific silencing of mRNAs in diversified eukaryotic cells. By introducing chemical modifications into synthetic siRNA (small interfering RNAs) building blocks, desirable "drug-like" properties can be imparted to the siRNAs. siRNAs containing chemical modifications show enhanced resistance towards nuclease degradation, suppression of immune stimulation as well as reduced "off-target" effects. To achieve in vivo delivery, certain chemical conjugates and novel formulations are being investigated. Alnylam is developing a pre-clinical and clinical pipeline of RNAi-based therapeutics to treat numerous diseases. Using the systemic treatment paradigm, we have demonstrated the ability to silence several liver gene targets, including PCSK9, that are important for treating metabolic diseases. PCSK9 has been genetically and experimentally implicated in LDLc regulation. We have shown in several animal models that silencing of PCSK9 in the liver by systemically delivered siRNA lowers both circulating PCSK9 protein levels in blood and plasma cholesterol levels. In the oncology area, we are developing an RNAi therapeutic for liver malignancies comprising liposomally formulated siRNAs targeting VEGF and the mitotic kinesin, KSP (Eg5, Kif11). For each target, potent and specific siRNA duplexes have been identified following extensive screening in cell culture. As expected, silencing of KSP in vitro leads to cell death in multiple tumor cell lines, while silencing of VEGF leads to inhibition of VEGF secretion into cell culture medium. To achieve hepatic delivery, liposomal formulations have been evaluated and shown to achieve silencing of hepatic gene expression with multiple siRNAs directed against distinct targets, including VEGF and KSP. To evaluate the therapeutic potential of this approach, pre-clinical safety and efficacy studies are being conducted.

3:00 28 Topical adenosine A2A receptor agonists for the treatment of poorly healing wounds
Bruce N. Cronstein, Bruce.Cronstein@nyumc.org and Paul R. Esserman. Department of Medicine, Division of Clinical Pharmacology, NYU School of Medicine, 550 First Ave, New York, NY 10016

Adenosine and its receptors play important roles in a number of physiologic and pharmacologic processes. Recent studies indicate that adenosine A2A receptors play central roles in promoting granulation tissue, new blood vessels and matrix, formation in dermal wounds. Making use of this understanding of the role of adenosine A2A receptors new agents have been designed to stimulate wound healing in poorly healing wounds, such as those suffered by patients with Diabetes Mellitus. Topical application of adenosine A2A receptor agonists stimulates new blood vessel formation and new collagen production by multiple mechanisms. These mechanisms will be discussed. In addition, clinical development of topical adenosine A2A receptor agonists for the treatment of diabetic foot ulcers is progressing and these results will be discussed.

3:30 29 Ocular drug delivery: Challenges and opportunities
Ashim K. Mitra, mitraa@umkc.edu, Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri Curator's Professor of Pharmacy and Chairman, 5005 Rockhill Road, Room 108C, Kansas City, MO 64110-2499

Ocular drug delivery has long been a challenging task to pharmaceutical scientists seeking to treat various ocular diseases affecting the anterior and posterior segments. In order to deliver therapeutic agents to target tissues, the unique anatomical barriers of the eye must be circumvented effectively, without causing any patient discomfort or alteration in protective physiological mechanisms. Topical mode of administration is the most preferred and convenient route to deliver drugs to the anterior segment. But the ocular bioavailability is extremely limited due to a highly selective corneal epithelium and various pre-corneal physiological processes resulting in the loss of drug. Drug delivery to the posterior segment is equally difficult due to the presence of blood aqueous barrier (BAB) and blood retinal barrier (BRB). The BRB is mainly comprised of retinal pigment epithelium (RPE) which regulates the diffusion of substances from the blood into the vitreous and retina. Hence the current challenge lies in not simply developing new therapeutic targets, but also finding more effective drug delivery technologies which do not cause alterations in the protective ocular mechanisms. These challenges have been successfully met in our laboratory by novel drug delivery strategies targeting the diseases affecting the anterior and posterior segment of the eye. Examples highlighting one novel delivery mechanism/system developed for anterior and posterior segment will be discussed.

Supported by National Eye Institute Grants R01EY09171-14 and R01EY10659-11

MONDAY MORNING

HIST - Classic Books in Chemistry V: Chemical Engineering
Hilton Garden Inn Salon B
James J. Bohning, Organizer
8:50   Introductory Remarks.
8:55 11 F.H. Thorp's Outlines of Industrial Chemistry
Gary D. Patterson, gp9a@andrew.cmu.edu, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213

Industrial chemistry has existed for millenia. Artisans have discovered specific recipes for the production of chemicals useful to humankind. Mostly, these recipes have either been kept as trade secrets or were merely collated as isolated artifacts. The perspective of Outlines of Industrial Chemistry by Frank Hall Thorp is that there are general principles that help to bring a more global character to the study of the practice of actual chemical manufacture. Thorp was inspired by the work of Lewis Mills Norton of MIT and followed him as Professor of Industrial Chemistry. There are many mechanical and thermal processes that are common to industrial practice. A thorough understanding of the operations of chemical manufacture provides a sound basis for the detailed consideration of specific substances. The total picture is presented from raw materials to primary product and important side products. Inorganic materials, organic materials and metals are treated in the context of actual industrial practice. The synoptic perspective developed in this landmark book became the hallmark of the emerging field of chemical engineering.

9:30 12 George E. Davis: A voice crying in the Midlands
Mary Ellen Bowden, mebowden@chemheritage.org, Chemical Heritage Foundation, 315 Chestnut St, Philadelphia, PA 19106

Englishman George E. Davis is generally credited with initiating the concept of chemical engineering. After at least twenty years in the chemical industry, in 1887 Davis gave a series of twelve lectures at the Manchester School of Technology, which formed the basis of his Handbook of Chemical Engineering (1901)—really a textbook and the first of its kind. There were already industrial chemistry books written for each chemical industry, but Davis organized his text by the basic operations common to many industries––later to be called “unit operations” by the American Arthur D. Little. The context in which Davis operated may help explain why his ideas found a more receptive audience in the United States than in England.

10:05 13 Principles of Chemical Engineering by William H. Walker, Warren K. Lewis, and William H. McAdams
Ron Reynolds, rreynolds@chemheritage.org, Chemical Heritage Foundation, 315 Chestnut Street, Philadelphia, PA 19106

The term Unit Operations was first coined by Arthur D. Little in 1915. The concept rapidly became an organizing principle to teach Chemical Engineering at an expanding number of university departments. The first edition appeared in 1923. Earlier texts had been organized by industry and were heavily oriented towards describing equipment used in the various industries. This text defined general or common physical operations that could then be considered the building blocks to design processes for a wide variety of applications. Each operation was linked to its underlying scientific principles. Later editions in 1927 and particularly 1937 addressed chemical transformations via chapters on reaction equilibria and reaction kinetics. After this landmark text, many authors developed books to address each unit operation in greater detail. The presentation also discusses evolving quantitative methods for equipment design in chemical engineering's early decades..

10:40   Intermission
10:50 14 Transport Phenomena: Success story in perspective
Barry L. Tarmy, bltarmy@comcast.net, 21 Water Lane, Berkeley Heights, NJ 07922

Bird, Stuart and Lightfoot's demonstratively successful Transport Phenomena was considered with some reservation a shift in chemical engineering thought and practice. In hindsight, its introduction in the late 1950's was optimal, having arrived midway between the introduction of the “Unit Operations” approach to chemical processing in the early 1900's and the coupling of chemistry and physics with engineering's technology and practices in the late 1900's and early 2000's. In addition to presenting some background on the authors, this presentation discusses chemical engineering's evolution from its “Unit Operations” processing base to the addition of the transport phenomena emphasis and then to more descriptive modeling and simulation of systems ranging in size from the industrial down to the micro-scale. With these advances has come increasing roles for chemical engineering in handling society's concerns with energy, health and the environment.

3:20 15 Perry's heavyweight handbook for chemical engineers
D. H. Michael Bowen, dhmbowen@yahoo.com, 8609 Ewing Drive, Bethesda, MD 20817

The discipline and profession of chemical engineering had already been going concerns for more than 30 years when the McGraw-Hill Book Co. published in 1934 the first edition of what was to become one of its all-time blockbuster sellers: Chemical Engineers Handbook. Written by a bevy of top engineers, most of them industrial, and edited initially by John H. Perry and later by his son Robert H. Perry and Cecil H. Chilton, the handbook became a “must have” reference tool for chemical and mechanical engineers. Edited by Don W. Green and currently in its 8th edition, it defies the increasing specialization of technology by covering its subject “from soup to nuts.” Who in 2008 wants or needs all this knowledge is another matter. The author will cover this amazing book and its long history from a personal perspective.

MONDAY AFTERNOON

MEDI - Molecular Imaging in Drug Development and Chemistry I
Pennsylvania Convention Center 204 A&B
Gabriela Chiosis, Peter R. Bernstein, Organizers
9:00 212 PET in neuroscience and drug development
Christer Halldin, Department of Clinical Neuroscience, Karolinska Institutet, Psychiatry Section, Karolinska Hospital, Stockholm, Sweden

PET provides a new way to image the function of a target and by elevating the mass, to pharmacologically modify the function of the target. The main applications of PET radioligands in brain research concern human neuropsychopharmacology and the discovery and development of novel drugs to be used in the therapy of psychiatric and neurological disorders. A basic problem in PET brain receptor studies is the lack of useful radioligands with ideal binding characteristics. Prerequisite criteria, such as high affinity and selectivity, need to be satisfied for a radioligand to reveal target binding sites in vivo. During the past decade over a hundred neurotransmitters have been identified in the human brain. Most of the currently used drugs for the treatment of psychiatric and neurological disorders interact with central neurotransmission. Molecular biological techniques have now revealed the existence of hundreds of novel targets for which little or no prior pharmacological or functional data existed. Due to the lack of data on the functional significance of these sites, pharmacologists are now challenged to find the physiological roles of these receptors and identify selective agents and possible therapeutic indications. During the past decade various 11C- and 18F-labeled radioligands have been developed for labeling some of the major central neuroreceptor systems. There is still a need to develop pure selective PET tracers for all the targets of the human brain. This presentation will review recent examples in neuroreceptor radioligand development and the clinical potential of in vivo imaging of neurotransmitter systems. The review will focus on studies with PET radiotracers in neuropsychopharmacological drug development. Drug research now benefits from the fast development of functional imaging techniques such as PET.

9:30 213 Translational applications of molecular imaging with PET
Yu-Shin Ding, yu-shin.ding@yale.edu, Dept. of Diagnostic Radiology, Yale University School of Medicine, 15 York St, New Haven, CT 06510

Modern PET research is enriched and strengthened by the integration of many disciplines, and advances in radiotracer chemistry have played a pivotal role in driving the field in new directions in studies of human physiology. At the heart of this development is the rapid incorporation of simple short-lived positron-emitting building blocks into organic compounds that can be used to map specific biochemical processes and the movement of drugs in living systems. This presentation will describe how we characterize radiotracers in animals, how we apply tracers to study neuroscience, and how we translate a promising radioligand from pre-clinical investigation in non-human primates to clinical research in humans.

10:00 214 Imaging agents for neurodegenerative diseases
H Kung, Department of Radiology and Pharmacology, University of Pennsylvania, 3700 Market St, Philadelphia, PA 19104

Neurodegenerative diseases are increasingly important in providing medical care for aging population. Parkinson's disease (PD) and Alzheimer's disease (AD) are two common neurodegenerative diseases. Advances in developing targeted imaging agents for positron emission tomography (PET) and single photon computed tomography (SPECT) have led to improvements in early diagnosis and monitoring disease progression by imaging methods. The first imaging agent for PD is 18F-6-fluoro-dopa is a false precursor, or substrate, for aromatic amino acid decarboxylase. All of the other dopamine transporter imaging agents are derivatives of tropane, a core structure of cocaine; they include 11C-CFT, 18F- or 123I-FP-CIT, 123I-β-CIP, 123I-altropane and 99mTc-TRODAT. Radiolabeled tetrabenazine derivatives, such as 11C-DTBZ, will target vesicular monoamine transporters inside the dopamine neurons. They may provide an alternative strategy in imaging the integrity of dopamine system as related to PD.

Formation of Abeta plaques in the brain is a hallmark of patients with AD and there is an underlying relationship between accumulation of Abeta in the brain and AD. Recently, radiolabeled tracers for binding Abeta plaques have been developed. Several Abeta specific binding agents which are derivatives of benzothiazole, stilbene or other related heterocyclic derivatives containing an electron-donating group on one of the aromatic rings, have been reported. They are simple, relatively small, neutral and lipophilic molecules displaying high binding affinity to Abeta aggregates (Ki at the range of 0.1-20 nM), they are suitable candidates as Abeta plaque-selective imaging agents. More importantly, they also showed ability to penetrate the intact blood-brain barrier, an essential pre-requisite for a useful plaque-imaging agent. These target-site-specific imaging agents may be useful for early detection and monitoring the progression and effectiveness of treatment of AD.

10:30 215 Synthesis and characterization of glycine transporter (GlyT1) PET ligands
Terence G. Hamill, terence_hamill@merck.com1, Andrew S. R. Jennings2, Richard T. Lewis2, Andrew Pike2, Steven Thomas2, Suzanne Wood2, Leslie Street2, Shil Patel1, David Wisnoski, david_wisnoski@merck.com3, Scott E. Wolkenberg, scott_wolkenberg@merck.com4, Craig Lindsley3, Zhijian Zhao3, Stephen M. Krause1, Christine Ryan1, Maria Michener1, David Williams1, Zhizhen Zeng1, Patricia Miller1, Kerry Riffel1, Waisi Eng1, Raymond E. Gibson1, Cyrille Sur1, Richard Hargreaves1, and H Donald Burns1. (1) Department of Imaging Research, Merck Research Laboratories, WP44D-2, West Point, PA 19486, (2) The Neuroscience Research Centre, Merck, Sharp and Dohme Research Laboratories, Terlings Park, Eastwick Road, Harlow, Essex, CM20 2QR, United Kingdom, (3) Medicinal Chemistry, Merck Research Laboratories, West Point, PA 19486, (4) Department of Medicinal Chemistry, Merck Research Laboratories, PO Box 4, WP14-1, West Point, PA 19486

Glycine transporters, which belong to the Na+/Cl- - dependent family of neurotransmitter transporters, are thought to regulate the synaptic levels of glycine, an amino acid inhibitory neurotransmitter that is a co-agonist for the NMDA receptor complex. Two glycine transporters, GlyT1 and GlyT2, have been identified. GlyT1 is found throughout the mammalian brain and has been shown to co-localize with NMDA receptors. Because hypofunction of the glutamatergic system has been suggested as a factor behind schizophrenia, increasing synaptic glycine levels by inhibiting its uptake by GlyT1 antagonists may be a useful therapy for schizophrenia. Having a PET tracer to determine central GlyT1 occupancy of therapeutic compounds would be an important tool to guide the selection of clinical doses for Phase IIa proof of concept studies. A series of PET tracers based on aryl amide 1 labelled with either carbon-11 or fluorine-18 were synthesized and evaluated as potential GlyT1 PET tracers. [18F]2, a potent, selective GlyT1 inhibitor, has excellent properties as a CNS receptor ligand and has been identified as a potential clinical PET tracer for imaging GlyT1. The in vitro and in vivo preclinical characterization of tracers leading to [18F]2 will be presented.

11:00 216 Quantitative imaging in drug discovery using positron emission tomography
Steven M. Larson, Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021

PET/CT imaging in oncology is rapidly expanding because of the benefits of evaluating the function as well as the structure of human tumors. These clinical benefits have greatly increased availability of PET/CT for patients' studies throughout the United States. In addition high-resolution animal imaging PET scanners have been developed, for experimental imaging including studies of the pharmacology of cancer drugs based on radiotracer methods.

At Memorial Sloan-Kettering cancer center we have applied these techniques to study small molecules, peptides, and radiolabeled antibodies in living animals and humans. We have imaged the pharmacodynamics of these drugs; e.g. the effect of HSP 90 inhibitors and signal transduction targeting drugs on nucleoside phosphorylation, glycolysis and expression of key biomolecules of her2 and AR. In this lecture we will present an overview of applications to cancer pharmacology and immunology in animals and man.

MONDAY AFTERNOON

CHAL - Non-Traditional Careers in Chemistry: CHAL's 25th Anniversary Series
Pennsylvania Convention Center 304
9:00 5 Lead scientist of Nanosystems Group
Carl Picconatto, picconatto@mitre.org, The Mitre Corporation, N2-30, 7515 Colshire Drive, McLean, VA 22102

Dr. Picconatto is presently the lead scientist of the Nanosystems Group of The MITRE Corporation in McLean, VA. His work involves both technical and programmatic support to various government nanotechnology programs as well as fundamental R&D in the area of nanotechnology and molecular electronics. Dr. Picconatto served in the United States Congress as the chief science advisor to Congresswoman Constance A. Morella, a senior member of the House Committee on Science. Dr. Picconatto was National Academy of Sciences Christine Mirzayan Winter 2001 Fellow and worked for the Committee on Science, Engineering, and Public Policy at the National Academy of Sciences. He holds a PhD in Chemistry from Columbia University and a BS from the University of Notre Dame.

9:30 6 Equity research
Michael Tong, michael.tong@wachovia.com, Wachovia Capital Markets, LLC, Equity Research, New York, NY 10001

Dr. Tong is part of Wachovia Capital Markets, LLC. Michael has a PhD in organic chemistry from Cornell University.

10:00 7 Independent consulting
Lisa M Balbes, lisa@balbes.com, Balbes Consultants, 648 Simmons Ave., Kirkwood, MO 63122

Dr. Balbes has been an independent consultant for almost 15 years. She is part of Balbes Consultants, which provides technical writing, editing, and information architecture services for technical companies. She has experience in producing documentation, peer-reviewed and trade journal articles, and workshops on technical writing topics. Additional expertise includes career development for scientists, and especially the use of new technologies (blogs, wikis, social networking, etc.) to increase efficiency and enhance professional development. She also has a PhD in chemistry from the University of North Carolina, Chapel Hill and a BA in Chemistry and Psychology, from Washington University.

10:30 8 Patent law
Monique Cole, mtc@bskb.com, Birch, Stewart, Kolasch & Birch, LLP, Suite 100 East, 8110 Gatehouse Road, Falls Church, VA 22042

Ms.Cole worked as an Examiner in chemical art units for nearly 9 years. She has worked as an associate in a law firm for about two years. Monique has a BS in chemistry from Norfolk State University, an MS in biotechnology from Johns Hopkins University and her JD from American University Washington College of Law.

11:00 9 Art conservation
Jennifer Mass, The Department of Art Conservation, University of Delaware, 303 Old College, Newark, DE 19716-2515

Jennifer Mass received her B.A. in chemistry from Franklin and Marshall College and her MS PhD in inorganic chemistry from Cornell University with a concentration in Materials Engineering. After graduating from Cornell she received a fellowship from the Andrew W. Mellon Foundation to conduct research at the Sherman Fairchild Center for Objects Conservation at the Metropolitan Museum of Art. Dr. Mass spent 1998-2001 as an assistant professor in the Art Conservation Department at The State University of New York College at Buffalo. During this time she continued her research on ancient Roman and Egyptian glassmaking practices, and began her studies in glassmaking in late antiquity Venice. In the fall of 2001 she joined Winterthur's Conservation Department and became an adjunct faculty member for WUDPAC. Dr. Mass is currently a Senior Scientist and Adjunct Assistant Professor in the department of Art Conservation at the University of Delaware.

11:30 Question and Answer

MONDAY AFTERNOON

PROF - The Use of New Technologies in Finding Employment
Loews Congress B
Lisa M Balbes, Organizer
1:30   Introductory Remarks
1:40 1 Employment websites for mid- and late-career scientists and engineers
John K. Borchardt, jkborchardt@aol.com, Southhaven Communications, 8010 Vista del Sol Drive, Houston, TX 77083-5039

There are a growing number of websites focused on helping mid- and late-career scientists and engineers find full-time, part-time and short-term employment. Some are operated by for-profit firms. Others, also for-profit, are operated to provide retirees of member companies employment opportunities. Member companies benefit by hiring highly qualified scientists and engineers from all member companies for specific assignments, usually short-term. Still other websites are non-profit and often are organized from the grassroots - by scientists and engineers hit by layoffs or forced into early retirement. Originally founded as a way to help former employees of a company keep in touch with each other, each of the over 150 websites is restricted to former employees of a particular firm. Still other websites enable chemists and engineers to submit solutions to problems posted by companies. While it may be a long-shot, submitting a winning solution can substantially supplement one's retirement income.

2:10 2 Using Google Tools to target companies, ace the interview, and land the perfect position
Jennifer L. Petoff, University Programs, Google Inc, 1600 Amphitheatre Pkwy, Mountain View, CA 94043

Technology lowers the activation barrier for candidates to apply to positions posted on job boards like Monster.com, ACS Careers, or on company websites. With just a few mouse clicks, a resume is on its way to a potential future employer. The downside is that it is more challenging to distinguish oneself from a flood of applicants. Standing out from the competition is the key to a successful job search. Job seekers can utilize a variety of online tools to differentiate themselves. Google Maps can be used to locate target companies with office, lab, or plant locations within a tolerable commute radius for those that are geographically constrained. Once an interview is secured, Google Search, Google Scholar, Google Patent Search, Google Finance, and Google News Alerts can all be utilized to learn in-depth information about the company and its employees. Google Notebook can be used to access and organize this research. This talk will describe various technology tools and illustrate how to effectively leverage each in a search for employment.

2:40 3 Application of on-line networking tools to establish a professional network, enhance career growth, and aid in the job search
Kenneth J. Barr, kenny.barr@gmail.com, Pharmaceutical Discovery, Amplyx Pharmaceuticals, Inc, 378 Cambridge Ave., Suite A, Palo Alto, CA 94306

As job security industry-wide continues to wane, each of us must remain vigilant in the management of our own careers. Whether you plan to remain indefinitely in your current field or are considering a transition to a new type of position, establishing and maintaining an effective professional network is a critical component in effective career development and also in the job search. This lecture will explore the utility of online networking tools (e.g. LinkedIn) in establishing, maintaining, and using your professional network.

3:10   Intermission
3:25 4 Catalyzing your job search using personal branding
Charles. J. Timmins, cjt@PersonalMarketingAdvisors.com, PMA, LLC, 5 Great Valley Parkway, Suite 214, Malvern, PA 19355

Job search is challenging. Your competition keeps raising the bar. Traditional approaches are proving less effective in securing interviews.

Personal Branding is a proven technology for attracting more employer interest, achieving traction and building relationships with hiring managers.

Candidates must communicate clear, concise perceptions of their credentials, accomplishments and potential to succeed moving forward.

In a sea awash with clutter and sameness, how will you “standout from the crowd"? It's all about differentiation.

Using proprietary 360° technology, Personal Branding provides data about what motivates you, what makes you “Y-O-U” and, most importantly, what makes you distinct from everyone seeking the same job.

If you offer something that is seen as truly unique, differentiated, valuable or compelling, then hiring managers will come after you; they'll compensate you more highly and treat you as you deserve to be treated.

The consequence of not communicating your personal brand is severe: “Be Distinct…or…Become Extinct”.

3:55 5 Pros and cons of using blogs and video-interviewing in a job search
Daniel J. Eustace, ACS, 5 Doty's Mill Rd., Acushnet, MA 02743

Resumes are great tools for introducing yourself to potential employers and recruiters. But resumes do little to foster the relationship between you and hiring managers.

Blogging gives you the opportunity to consistently authenticate the skills represented in your resume and continue a conversation with the people who need to know who you are and benefit from those insights.

Readers expect to see quality information from a trusted source. Readers also wish to be pointed to resources they are unaware of to provide them a unique advantage or perspective. You want them to feel comfortable with you and the information you present so they keep coming back to your blog.

The best blogs are those that create community for a specific niche. Your candidacy for one industry may not be represented for some positions unless it addresses common elements relevant to positions you seek.

Video interviewing is “quantum leap” difference.

4:25 6 Networking using Second Life
Jean-Claude Bradley, bradlejc@drexel.edu, Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104

Abstract text not available.

4:55 Concluding Remarks

MONDAY AFTERNOON

MEDI - Molecular Imaging in Drug Development and Chemistry II
Pennsylvania Convention Center 204 A&B
Charles S. Elmore, Peter R. Bernstein, Organizers
1:30 223 AZ10419369 a translational tool for 5-HT1B receptors
M. Edward Pierson, edward.pierson@astrazeneca.com1, Jan Andersson2, Svante Nyberg3, J. Söderström3, Dennis J. McCarthy1, Sjoerd J. Finnema2, Katarina Varnäs2, Akihiro Takano2, Per Karlsson2, Balázs Gulyás2, Mark E. Powell1, J. Richard Heys4, William Potts1, Donna Maier1, Amy Medd1, Cynthia D. Sobotka-Briner1, Nicholas Seneca5, Lars Farde2, and Christer Halldin2. (1) AstraZeneca Pharmaceuticals, PO Box 15437, Wilmington, DE 19850, (2) Department of Clinical Neuroscience, Karolinska Institutet, Psychiatry Section, Karolinska University Hospital, S-17176 Stockholm, Sweden, (3) Clinical Neuroscience, AstraZeneca Pharmaceuticals, S-151 85 Södertälje, Sweden, (4) CNS Discovery, AstraZeneca Pharmaceuticals, Wilmington, DE 19850, (5) Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD 20892

The 5-HT1B receptor is a potential pharmacological target in the treatment of depression. We report the use of [11C]AZ10419369 (5-methyl-8-(4-methyl-piperazin-1-yl)-4-oxo-4H-chromene-2-carboxylic acid (4-morpholin-4-yl-phenyl)-amide), a novel high affinity radioligand, for in vivo visualization of 5-HT1B receptors. [11C]AZ10419369 was prepared by N-methylation of the N-H precursor, using carbon-11 methyl triflate in >99% radiochemical purity and specific activity of >6000 Ci/mmol. Regional brain uptake patterns of [11C]AZ10419369 were characterized by PET measurements in primates. After iv injection of [11C]AZ10419369, 3-4% was in brain after 7.5 minutes. The highest uptake of radioactivity was in the occipital cortex and basal ganglia, and lowest in the cerebellum in accord with autoradiographic studies performed using [3H]AZ10419369. In primates and guinea pigs pre-treated with the selective 5-HT1B receptor antagonists, binding of radiolabeled AZ10419369 was reduced in a dose-dependent manner, consistent with specific binding to 5-HT1B receptors. These data support [3H] and [11C]AZ10419369 as a suitable radioligand for imaging 5-HT1B receptors and determining receptor occupancy of test compounds.

2:00 224 Synthesis, characterization and in vivo imaging in nonhuman primates of a series of carbon-11 reboxetine analogs as norepinephrine transporter (NET) PET imaging agents
Fanxing Zeng1, Nachwa Jarkas1, Ronald J. Voll1, John R. Votaw1, Leonard Howell2, Clinton D. Kilts2, Charles B. Nemeroff2, and Mark M. Goodman, mgoodma@emory.edu1. (1) Department of Radiology, Emory University, 1364 Clifton Road NE, Atlanta, GA 30322, (2) Psychiatry, Emory University, Yerkes Primate Center, Atlanta, GA 30322

Objectives: The NET is a molecular target for the treatment of depression, anxiety disorder, and attention-deficit/hyperactivity disorder (ADHD). The development of radioligands to map the NET by positron emission tomography (PET) presents opportunities to define the functional status and pharmacology of the NET in the living human brain. The objective of this study was to investigate the regional uptake, specificity and binding kinetics of a series of carbon-11 labeled reboxetine analogs, (2S,3S)-2-[α-(2-(methyl)phenoxy)benzyl]morpholine (1), (2S,3S)-2-[ α-(2-(methylthio)phenoxy)benzyl]morpholine (2), (2S,3S)-2-[α-(2-(methylthiophenylthio)phenylmethyl]morpholine (3), and (2S,3S)-2-[ α -(2-methoxyphenylthio)phenylmethyl]morpholine (4) using PET imaging.

Methods and results: In vitro binding in cells transfected to express human NET, SERT and DAT gave Ki's (nM) = 1 (1), 2 (2), 0.8 (3), and 0.6 (4) (vs [3H]nisoxetine), 94 (1), 91 (2), 10 (3)and 13 (4) (vs [3H]citalopram) and 328, (1), 6506 (2), 4054 (3), and 1440 (4) (vs [125I]RTI-55). The in vivo regional brain uptake of [11C] (1), (2), (3), and (4) were determined in anesthetized and awake rhesus monkeys after administration of ~15 mCi. [11C] (1), (2), (3), and (4) showed high uptake in NET rich regions (thalamus, locus ceruleus, anterior cingulate and cerebellum) and displayed favorable kinetics with a peak uptake at 22.5-60 min. Blocking studies carried out with the NET ligand desipramine (0.125 & 0.25 mg/kg) 30 min prior to injection of [11C] (1), (2), (3), and (4) showed significant reduction of the radioactivity from the NET rich regions proving NET specificity.

Conclusions: This preliminary studies demonstrate that [11C] (1), (2), (3), and (4) show fast kinetics and in vivo specificity, selectivity for CNS NET and could be useful for assessing alterations in brain NET. Research supported by NIMH and Wyeth Ayerst.

2:30 225 Tools for monitoring therapeutic interventions in neurodegenerative diseases
Jorge R Barrio, jbarrio@mednet.ucla.edu1, Vladimir Kepe1, S-C. Huang1, N Satyamurthy1, and Gary W Small2. (1) Department of Molecular and Medical Pharmacology, UCLA School of Medicine, 10833 Le Conte Ave, Los Angeles, CA 90095, (2) Neuropsychiatric Institute, UCLA School of Medicine, 10833 Le Conte Ave, Los Angeles, CA 90095

Hemispheric cortical surface mapping of 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ([F-18]FDDNP) binding is a powerful tool for assessment and visualization of the rate of brain pathology deposition. With several hundred patients performed to date, including severe and moderate AD subjects, patients with mild cognitive impairment (MCI), presenilin-1 and presenilin-2 patients as well as patients with other forms of dementias (e.g., fronto-temporal dementias, Down syndrome, prion diseases and viral dementias) significantly greater accumulation of [F-18]FDDNP is observed in brain areas expected to have amyloid, NFTs or prion aggregates. In AD the distribution of [F-18]FDDNP accumulation correlates well with behavioral measures (e.g., MMSE scores) and follows known patterns of pathological distribution seen in autopsy in the same patients and in brain specimens by Braak and Braak. The imaging approach permits monitoring of disease progression and also monitoring of therapeutic interventions in the same patient or in groups of patients. Prion deposition in Gerstmann-Sträussler-Scheinker (GSS) disease can be equally monitored. A strong correlation of [F-18]FDDNP binding, cell losses in hippocampus and decreased glucose utilization ([F-18]FDG PET) in several neocortical regions was found in the same AD and MCI subjects. Therefore a battery of molecular imaging probes for the assessment of specific biochemical and cellular events in the living human brain are currently available.

3:00 226 Strategies for developing and labeling radiopharmaceuticals for imaging estrogen receptor presence and function in breast cancer
John A. Katzenellenbogen, jkatzene@uiuc.edu, School of Chemical Sciences, University of Illinois, 600 S. Mathews Ave., Urbana, IL 61801

Elevated levels of steroid receptors are found in certain tumors, and these receptors serve as key targets for endocrine therapies involving hormone antagonists and endogenous hormone depletion treatments that can often be very effective, with minimal side effects. We have designed high affinity steroid receptor ligands, labeled with the positron-emitting radionuclide fluorine-18, for positron emission tomographic imaging of estrogen and progesterone receptors in breast tumors and androgen receptors in prostate cancers. This non-invasive determination of receptor levels in the tumors provides valuable information in selecting both breast and prostate cancer patients most likely to benefit from endocrine therapy. In addition, a hormone challenge test which images hormone-induced changes in tumor metabolism is proving highly predictive of response to endocrine therapies in breast cancer. We have also investigated ways in which steroid receptor ligands might be labeled with the more widely available radionuclide, technetium-99m.

3:30 227 PET Radioligand discovery and development for mGluR5 receptors
Victor W. Pike, pikev@mail.nih.gov, Fabrice G. Siméon, simeonf@mail.nih.gov, Sami S Zoghbi, H. Umesha Shetty, Amira K. Brown, and Robert B. Innis. Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm B3 C346A, 10 Center Drive, Bethesda, MD 20892

Brain mGluR5 receptors have become of interest as a therapeutic target for several neuropsychiatric disorders, including cocaine addiction and Fragile X. An ability to image and quantify mGluR5 receptors in living human brain with positron emission tomgraphy (PET) and a suitable radioligand would permit unique investigations of the role of mGluR5 receptors in these disorders. Furthermore, such a radioligand could be useful for establishing the therapeutic doses of mGluR5-targetted developmental drugs to be used in clinical trials, through receptor occupancy studies. Here we describe the discovery and development of a successful PET radioligand for imaging mGluR5 receptors in human brain.

MONDAY AFTERNOON

TOXI - Chemical Biology of Epigenetics
Loews Regency B
Natalia Tretyakova, Lawrence Sowers, Organizers
1:30 Introductory Remarks
1:40 23 DNA methylation can be monitored by isotope tracers and GC/MS
Lawrence Sowers, lsowers@llu.edu and Jason Herring. Department of Basic Science, Loma Linda University, 11234 Anderson Street, Loma Linda, California, CA 92354

Reactivation of genes silenced by methylation is of great interest to the medical field for cancer treatment and prevention as well as for development of new medical therapeutics. Current research has focused on the area of epigenetic regulation via cytosine methylation. Our studies use stable isotopes to label newly incorporated pyrimidines incorporated into DNA and newly methylated cytosines independently. This technique allowed us to verify the presumption that methylation closely follows DNA replication and led to the discovery of a process where 5-methylcytosine residues on the parental strand are in dynamic flux. Furthermore, our technique opens the door for the monitoring of cellular toxicity via DNA replication and methylation perturbations resulting from methylation inhibitors and other drugs.

1:55 24 Endogenous cytosine methylation influences the formation and repair of DNA adducts at CpG dinucleotides
Natalia Tretyakova, Rebecca Guza, and Brock Matter. Department of Medicinal Chemistry and the Cancer Center, University of Minnesota, 425 East River Road, 790 CCRB, Minneapolis, MN 55455

Lung tumors of smokers typically contain G to T mutations within endogenously methylated MeCG dinucleotides of the p53 tumor suppressor gene, e.g. codons 157, 158, 245, 248, and 273 (MeC = 5-methylcytosine). The presence of MeC at these sites may mediate the reactivity of neighboring guanine base towards tobacco carcinogens, leading to targeted binding of metabolically activated tobacco carcinogens to MeCG sequences. We have employed stable isotope labeling HPLC-ESI+-MS/MS methodology to analyze the formation of guanine lesions of benzo[a]pyrene diolepoxide (BPDE), NNK, acetaldehyde, and reactive oxygen species within DNA duplexes representing p53 mutational "hot spots" and surrounding sequences. We found that all four N2-BPDE-dG diastereomers and oxidative dG lesions were formed preferentially at guanine bases within MeCG dinucleotides, including frequently mutated p53 codons 157, 158, 245, 248, and 273. MeC in the basepaired position was largely responsible for this effect. In contrast, MeC inhibited the formation of NNK-induced O6-Me-dG and O6-POB-dG adducts, leading to poor adduct yields at methylated CG dinucleotides in the p53 gene. The structural basis for these effects was investigated by conducting structure-activity studies with a series of MeC structural analogs.

2:25 25 Genetics and epigenetics of metal carcinogenesis
Anatoly Zhitkovich, anatoly_zhitkovich@brown.edu, Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Providence, RI 02912

Carcinogenic metals have long thought to act primarily as the indirect inducers of oxidative DNA damage. However, recent discoveries revealed the importance of active stress signaling and nonoxidative processes targeting genome structure. Cellular ascorbate appears to play a central role in epigenetic and genotoxic effects of more than one metal. High ascorbate levels are important for rapid Cr(VI) reduction and efficient removal of histone methyl groups by Fe(II)-dependent demethylases that require ascorbate as a cofactor. Depletion of ascorbate was found to be largely responsible for the ability of Ni2+ and Co2+ ions to activate HIF1alpha transcriptional factor and the subsequent expression of hypoxia-inducible genes. Hypoxic signaling leads to chromatin condensation and low expression of DNA repair genes. Epigenetic inactivation of genome maintenance mechanisms promotes persistence of metal-induced DNA damage and its fixation in the form of mutations and gross chromosomal rearrangements.

2:55 Intermission
3:05 26 Inflammation mediated DNA damage induces epigenetic changes
Lawrence Sowers, lsowers@llu.edu and Victoria Valinluck Lao. Department of Basic Science, Loma Linda University, 11234 Anderson Street, Loma Linda, California, CA 92354

DNA damage, inflammation and alterations in cytosine methylation patterns have all been associated with the development of cancer in humans; however, no mechanistic link has yet been established. Recent studies on inflammation-mediated DNA damage may have provided important new clues. The neutrophil- derived DNA damage product, 5-chlorocytosine, has been shown to mimic 5-methylcytosine in in vitro biochemical studies. In this study, we demonstrate that the random incorporation of 5-chlorocytosine residues into the DNA of dividing vertebrate cells can result in heritable changes in cytosine methylation patterns and result in gene silencing. Gene reactivation studies with the methylase inhibitor 5-aza-2'-deoxycytidine and bisulfite sequencing confirm that the observed effect is epigenetic and not mutagenic. These studies further strengthen a mechanistic link between inflammation-mediated DNA damage, epigenetic changes and the development of human cancer.

3:20 27 Impact of carcinogen-DNA adducts on DNA methylation
Nicholas E. Geacintov, nicholas.geacintov@nyu.edu, Department of Chemistry, New York University, 31 Washington Place, Brown Building, Room 453, New York, NY 10003 and Elizaveta S Gromova, gromova@libro.genebee.msu.ru, Chemistry Department, Moscow M.V. Lomonossov State University, Moscow, 119992, Russia.

The methylation of DNA at CpG dinucleotides by DNA methyltransferases (MTases) is an epigenetic alteration of the genome that plays an important role in the regulation of gene expression in eukaryotes. Abnormalities in the levels of methylation are one of the hallmarks of tumorigenesis. Polycyclic aromatic hydrocarbons such as benzo[a]pyrene are ubiquitous environmental pollutants that are metabolized in vivo to highly genotoxic and tumorigenic diol epoxides. The latter react with cellular DNA to form covalent adducts that can, if not removed by cellular DNA repair mechanisms, cause mutations and the initiation of tumorigenesis in animal models, and probably in humans. The potential impact of such lesions on DNA methylation has received relatively little attention. Utilizing an in vitro biochemical approach, it is shown that BPDE-derived DNA lesions can alter DNA methylation at CpG dinucleotide sites in a manner that depends on the conformational properties of the lesions and their positions within the DNA recognition sequence. The results of these studies suggest that PAH diol epoxides may initiate cancer not only by genotoxic mechanisms, but might also contribute to tumor development by epigenetic effects that involve changes in DNA methylation status.

3:50 28 DNA methylation inhibitors for the treatment of cancer
Allen S. Yang, allenyan@usc.edu, USC / Norris Comprehensive Cancer Center, University of Southern California, 1975 Zonal Avenue, KAM-110, Los Angeles, California, CA 90089-9023

The methylation of cytosine in DNA is an important part in the epigenetic regulation of gene expression. DNA methylation along with histone modifications have also been identified as important targets for cancer therapy and possibly other diseases. Currently there are two nucleosides, azacitidine and decitabine, that are FDA approved for the treatment of myelodysplastic syndrome, a cancer of the blood. These drugs are believed to have their clinical effect through inhibition of DNA methylation that plays a role in control of gene expression. We will examine the mechanism by which these drugs inhibit DNA methylation, explore the mechanism of clinical effect in cancer, and discuss how these drugs may be improved.

TUESDAY MORNING

COMP - Drug Discovery
Sofitel Nice
Irache Visiers, Organizer; Min Wu, Presiding
8:00 144 Characterizing carbohydrate-protein interactions: Protein contact surface mapping employing hydroxyl radicals, mass spectrometry and MD simulations
Olga Charvatova, charvato@uga.edu and Robert J. Woods, rwoods@ccrc.uga.edu. Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602

For a large number of biomolecular complexes, it is not possible to apply traditional methods such as x-ray crystallography, particularly for oligosaccharide-protein interactions. While NMR methods such as STD-NMR can identify protons in the ligand that are close to the protein surface, these methods are not generally applicable to the protein. To address the lack of 3D information pertaining to the regions of the protein directly involved in the interaction with ligand, we are developing a surface mapping technique. Hydroxyl radicals react with the amino acid side chains and so can provide a generic labeling reagent, generated in situ by pulsed laser irradiation. Subsequent quantification of amino acid oxidation levels follows a proteomics approach employing MS/MS sequencing of tryptic peptides. We demonstrate that, for any given residue, the extent of surface modification is proportional to the side chain solvent accessibility. In order to interpret the experimental data, MD simulations of the complex are performed to provide theoretical values for the difference in solvent accessibility for the bound and free forms of the protein.

This experimental approach may be readily combined with theoretical docking methods to provide validation of the computational results, or potentially to guide the docking algorithm.

8:25 145 Geometric protein structure analysis approaches for designing inhibitors of protein-protein interactions
Deepak Bandyopadhyay, Deepak.2.Bandyopadhyay@gsk.com, Computational and Structural Chemistry, GlaxoSmithKline, 1250 S. Collegeville Rd, Mail Code UP12-210, Collegeville, PA 19426

Protein-protein interactions (PPI) were until recently considered difficult targets for small-molecule drug discovery, though with new developments and a new understanding of this field, that view is changing. We apply techniques from computational biology (particularly geometric analysis of protein structure) to describe and probe protein-protein interfaces, and describe how the resulting insights are valuable in a drug discovery setting. We have computed and categorized interfaces for a variety of protein-protein interaction targets, and are using the validated correspondence between deep/persistent parts of the interface surface and hotspot residues for structure-based design of PPI inhibitors. We find that functions computed on the interface give potent descriptors of protein-protein binding affinity, an important step forward in this field. Further, we apply and validate interface surface computation and analysis methods in the context of protein-small-molecule interaction, comparing them with established methods.

8:50 146 QUAPO: Quantitative analysis of pooling in high-throughput drug screening
Raghunandan M. Kainkaryam, raghu@umich.edu, Department of Chemical Engineering, University of Michigan, 3074 H. H. Dow Building, 2300 Hayward, Ann Arbor, MI 48109 and Peter J. Woolf, pwoolf@umich.edu, Department of Chemical Engineering and Bioinformatics Program, University of Michigan, 3074 H. H. Dow Building, 2300 Hayward, Ann Arbor, MI 48109

Pooling in high-throughput drug screening involves testing mixtures of compounds in a biochemical assay to minimize the number of tests required to screen a library for active compounds. In this talk, we will present recent work in our group for designing assay pooling schemes tailored for drug screening highlighting their resource savings, identification guarantees, error-correcting abilities and drug screening-specific modifications. Furthermore, we will present a biophysically relevant error-tolerant pooling strategy called Quantitative Analysis of Pooling (QUAPO). QUAPO utilizes state-of-the-art compression and decoding techniques from the field of compressed sensing, along with simple biochemical models, to obtain quantitative binding information from a primary drug screen while minimizing the number of tests needed and handling experimental error. We will present results from pooled in-silico experiments showcasing QUAPO's ability to acquire robust quantitative binding information using data from a small competitive binding and a large competitive inhibition screen.

9:15 147 A technique for generating 3-D alignments of multiple ligands from 1-D alignments
David J. Diller, ddiller@pharmacop.com, Molecular Modeling, Pharmacopeia, Box 5350, Princeton, NJ 08543-5350

We describe and demonstrate a new method for the simultaneous, fully flexible alignment of multiple molecules with a common biological activity. The key aspect of the algorithm is that the alignment problem is first solved in a lower dimensional space, in this case using the one-dimensional representations of the molecules. The three-dimensional alignment is then guided by constraints derived from the one-dimensional alignment. We demonstrate the technique with a few test cases and compare to other commonly used alignment techniques.

9:40 148 Focused Library Design: An integration of knowledge-based information and multiple modern drug designing approaches
Minghu Song, msong@syntapharma.com1, Weiwen Ying1, Mei Zhang2, Vincent Yu2, Christopher Borella1, Lijun Sun1, and James Barsoum2. (1) Department of Chemistry, Synta Pharmaceuticals, 45 Hartwell Ave., Lexington, MA 02421, (2) Deparment of Biology, Synta Pharmaceuticals, 45 Hartwell Ave., Lexington, MA 19421

In recent years, there has been increasing interest in smaller focused or targeted libraries against specific biological targets or gene families. Such target-family-oriented libraries are usually pursued with a variety of design approaches, including combinatorial libraries of privileged scaffolds, structure-based docking and 2D/3D pharmacophores or fingerprints. In this talk, we will present our recent works on GPCR focused library and how we combine knowledge-based information with multiple traditional/modern designing methodologies to further guide the design.

10:05 Intermission
10:15 149 Molecular dynamics and binding studies on human paraoxonase 1: In silico optimization of activity against chemical nerve agents
Toby T. Sanan, tsanan@chemistry.ohio-state.edu, Peng Tao, tao.21@osu.edu, Sivaramakrishnan Muthukrishnan, muthukrishnan.2@osu.edu, Carrigan J. Hayes, and Christopher M. Hadad, hadad@chemistry.ohio-state.edu. Department of Chemistry, The Ohio State University, Columbus, OH 43210

Human Paraoxonase 1 (huPON1) is an endogenous human protein which has been identified as having the ability to catalytically hydrolyze organophosphorous nerve agents, as well as a number of other substrates including aryl esters and lactones. At present, the mechanism of action of the enzyme is still under debate, and the majority of the available structural information comes from the crystal structure of a gene-shuffled protein with 86% sequence homology with the human enzyme, but with no substrate or inhibitor bound in the active site. Computational models have been prepared for both the human wild-type enzyme, as well as the gene-shuffled variant, and extensive (20 ns) molecular dynamics (MD) simulations were performed for these models. Mutant proteins were prepared in silico to rationalize experimental mutagenesis studies, and these models were also relaxed using MD techniques. Molecular docking simulations have been performed to explore the nature of substrate binding, and critical residues for binding and reactivity have been identified. Hybrid QM/MM simulations were performed to analyze potential reaction mechanisms in conjunction with the binding studies.

10:40 150 Protein loop modeling for structure-based drug design
Karen A. Rossi, karen.rossi@bms.com, Akbar Nayeem, akbar.nayeem@bms.com, and Stanley R. Krystek Jr., stanley.krystek@bms.com. Computer-Assisted Drug Design, Bristol-Myers Squibb Company, P.O. Box 5400, Princeton, NJ 08543-5400

A key issue in protein modeling for structure-based drug design is the accurate modeling of loops, particularly when the loop in question is within interaction distance of the bound ligand. This study takes a critical look at modeled loops, evaluating them in terms of backbone and side-chain conformations with respect to the conformations found in the crystal structure. The computational protocols used for generating the loops include Monte Carlo searching, ab initio and knowledge-based methods. Even those loops that are well modeled with respect to the backbone atoms, however, may be poorly modeled with respect to side-chains and therefore may be unsuitable for ligand docking. With this concern in mind, we are specifically exploring the ability to accurately model the side-chains for those loops that show the best backbone RMSD using a variety of methods.

11:05 151 Subtype selectivity of the serotonin 5-HT2B receptor antagonists: Molecular modeling study
Soo-Kyung Kim, skkim@wag.caltech.edu, Youyong Li, youyong@gmail.com, Ravinder Abrol, and William A. Goddard III, wag@wag.caltech.edu. Materials and Process Simulation Center, California Institute of Technology, 1200 East California Blvd., Beckman Institute (Mail Stop: 139-74) Rm. 054a, Pasadena, CA 91125

Three 5-HT2 receptors (2A, 2B, 2C) are major drug targets such as schizophrenia, feeding disorders, perception, depression, migraines, hypertension, anxiety, hallucinogens, and gastrointestinal dysfunctions. The first 5HT2B/2C indol urea antagonist (SB-206553, pA2, 2B: 8.5, 2C: 8.3) exhibited >100-fold selectivity over the 2A. Conformational restriction within a six membered ring produced a 100-fold selectivity for the 5-HT2B receptors (pA2=7.27) over 2A/2C. To understand the subtype-selectivity, MembStruk and GenMSCDock were used to predict. The docking results show the sub-type selective key residues (2.53, 3.29, 4.60, 6.58). The simulations in a membrane environment reveal that the dissimilarity of water migration into the NPxxY motif (three times more waters in the agonist-bound structure) and the more fluctuation of agonist affect the conformational change upon activation differently. The refined 3D model would help the rational design of novel drugs for the 5-HT2B antagonists with higher subtype selectivity and lesser side effect.

11:30 152 Hologram QSAR studies on two types of PTP1B inhibitors
Yuanhua Cheng, cheng-yh06@mails.tsinghua.edu.cn1, Mei Zhou, zhou_mei@mails.gscas.ac.cn2, Mingjuan Ji2, and Fushi Zhang1. (1) Department of Chemistry, Tsinghua University, Department of Chemistry, Tsinghua University, Haidian District, Beijing, 100084, (2) College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, 19A Yu Quan Road, P. O. Box 3908, Beijing, 100039, China

In this research, two-dimensional quantitative structure-activity relationship (QSAR) studies for a set of protein tyrosine phosphatase 1B (PTP1B) inhibitors, which include 39 2-(oxalylamino) benzoic acid (OBA) and 60 benzofuran and benzothiophene biphenyls (BBB), were conducted using the hologram QSAR approach. The HQSAR models were systematically optimized by varying the molecular fragment sizes, the fragment sub-structural types, and the molecular hologram lengths to reduce the standard errors. The best HQSAR models were statistically significant in the Leave-One-Out analysis: the correlation coefficient square (q2) are 0.751 and 0.715 for the OBA analogues and the BBB analogues, respectively. In comparison to the comparative molecular field analysis (CoMFA) models, the HQSAR models achieved a much better predictive ability. We believe that the two models are useful in high-throughput screening the promising inhibitors of PTP1B, given their high predictive ability and computational efficiency. The analysis of the key fragments identified by the HQSAR models can guide us to design more potent inhibitors.

TUESDAY MORNING

TOXI - Drug Safety
Loews Regency B
Nicholas A. Meanwell, F. Peter Guengerich, Organizers
8:30 Introductory Remarks
8:40 29 Prediction of cytochrome P450-based drug-drug interactions from in vitro information
R. Scott Obach, Pharmacokinetics, Pharmacodynamics and Drug Metabolism, Pfizer Inc, Groton, CT 06340

A frequent mechanism that underlies pharmacokinetic-based drug-drug interactions (DDI) is through inhibition of cytoxchrome P450 enzymes that are responsible for the metabolic clearance of a majority of drugs. With our understanding of the multiplicity of human P450 enzymes and their substrate and inhibitor specificities, we have been able to use in vitro data to predict the magnitude of DDI for new drugs that inhibit or inactivate these enzymes. Prediction of DDI from in vitro data requires a conceptual picture of drug disposition, with particular emphasis on the liver and intestine, such that in vitro inhibition or inactivation data can be used in equations that model these drug disposition properties for the inhibitor and the drug affected by the inhibitor. The process by which this is done will be reviewed in this presentation and the inherent assumptions and shortcomings will be described. This is important because the vitro tools used to determine which P450 enzymes can be inhibited by a new drug have become commonplace, and such experiments have become an expectation for supporting the development and registration of new drugs.

9:30 30 Grapefruit: A food that potently impairs intestinal drug metabolism and uptake transport clinically
David G. Bailey, Division of Clinical Pharmacology, Department of Medicine, London Health Sciences Centre and Department of Physiology & Pharmaco, University of Western Ontario, 375 South St, London, ON N6A 4G5

The 1991 report that grapefruit juice caused 3-fold higher oral bioavailability of the antihypertensive medication, felodipine, provided the primary important clinical example of food-mediated inactivation of first-pass drug metabolism. Many scientists subsequently significantly contributed to the understanding of this type of interaction. More than 40 medications, some of which are highly prescribed or essential medications, now appear to carry the risk of a grapefruit - induced adverse drug interaction. Recently, grapefruit juice was also shown to lower the oral bioavailability of other drugs through inhibition of a specific intestinal uptake transporter. For each type of interaction, the discovery, mechanism and active ingredient(s) will be reviewed. Clinically relevant issues (volume-effect relationships, individual variability and reproducibility, duration of effect, repeated juice consumption, age and affected drugs) will be discussed. The action of other fruit juices and the potential clinical usefulness of inclusion of the active ingredient(s) into drug formulations will be considered.

10:20 31 Pregnane X receptor: Structure and binding properties of xenobiotics
Michael A. Sinz, Department of Metabolism & Pharmacokinetics, Bristol-Myers Squibb Research & Development, 5 Research Parkway, Wallingford, CT 06492

The pregnane X receptor (PXR) is a nuclear hormone receptor responsible for transcriptional regulation of drug metabolizing enzymes. Most importantly, PXR upregulates the expression of CYP3A4 which significantly increases the metabolic clearance of drugs ultimately resulting in therapeutic failure. PXR is unlike most nuclear hormone receptors in that a wide variety of agonist can bind to the ligand binding domain which is extremely large and hydrophobic with several polar residues distributed throughout. Pharmacophore models and ligand bound crystal structure data indicate that significant agonist binding requires the ligand to contain at least one hydrogen bond acceptor group along with 3-5 hydrophobic interactions. Chemical modifications are being elucidated that disrupt these interactions between agonists and ligand binding domain residues. These alterations in structure allow the medicinal chemist to develop new chemical entities which reduce the liability of PXR activation (as measured by ligand binding or transactivation assays) and drug-drug interaction potential.

11:10 32 Humanized mouse models to predict chemical safety and metabolism
Frank J. Gonzalez, fjgonz@helix.nih.gov1, Xiaochao Ma1, Qian Yang1, and Jeffrey R Idle, jeff@cyp2d6.com2. (1) Laboratory of Metabolism, National Cancer Institute, Bethesda, MA 20892, (2) Institute of Pharmacology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic

Pregnane X receptor (PXR) and peroxisome proliferator-activated receptor alpha (PPARalpha) are members of the nuclear receptor superfamily that heterodimerize with the retinoid X receptor and activate target gene expression; they are widely considered as xenosensors since their ligands include a wide variety of structurally diverse chemicals including drugs and industrial agents. PXR is responsible for regulation of the cytochromes P450 3A (CYP3A) forms that metabolize many drugs while PPARalpha is involved in the hepatocarcinogenicity of the non-genotoxic peroxisome proliferators. Most importantly there are major species differences between the homologs of these receptors, especially between rodents and humans thus making animals inappropriate for accurately testing the safety of PXR and PPARalpha. To this end, mice humanized for PXR and PPARalpha were produced and characterized. Specific examples of the value of these new models, including the role of PXR in drug-drug interactions and PPARalpha in hepatocarcinogenesis, will be discussed.

TUESDAY AFTERNOON

TOXI - Cytochrome P450 Structure, Function, and Mechanism
Loews Regency B
F. Peter Guengerich, Organizer
1:30 33 Recent advances in structural characterization of drug metabolizing P450 monooxygenases
Eric F. Johnson, johnson@scripps.edu1, Stefan Sansen1, and C. David Stout2. (1) Department of Molecular and Experimental Medicine, The Scripps Research Institute, MEM-255, 10550 North Torrey Pines Road, La Jolla, CA 93027-9701, (2) Department of Molecular Biology, The Scripps Research Institute, MEM-255, 10550 North Torrey Pines Road, La Jolla, CA 93027-9701

Crystal structures of the principal human drug metabolizing P450s reveal distinct active site architectures that underlie individual contributions to xenobiotic oxidations. The more conserved and rigid structural features support heme binding and redox partner interactions, whereas flexibility of the substrate-binding site contributes to broad substrate recognition as well as substrate access to the cavity. P450/substrate interactions are predominately hydrophobic leading to substrate selectivity based largely on size and fit. Selective polar interactions further modulate relative selectivity. The binding of two or more substrate molecules can lead to complex kinetic properties. Major challenges for the future are to better define the contributions of protein flexibility in substrate binding and to incorporate protein flexibility into methods for predicting substrate binding. Additionally, there is a need to develop methods to accurately predict the binding of substrate pairs that lead to complex pharmacokinetic properties. Supported by NIH grant GM031001 and Pfizer.

2:20 34 Mechanism-based inactivation of human cytochrome P450s
Paul F. Hollenberg, phollen@umich.edu, Hsia-lien Lin, and Ute M. Kent. Department of Pharmacology, University of Michigan, 1150 W. Medical Center Dr, 1301 MSRB III, Ann Arbor, MI 48109-0632

The cytochrome P450s catalyze the metabolic activation of a wide variety of xenobiotics to reactive intermediates that can react with cellular macromolecules leading to toxicity. These reactive intermediates can also react with moieties in the P450 active sites resulting in covalent adduct formation that leads to irreversible (mechanism-based) inactivation. Experimental approaches for characterizing mechanism-based inactivators, criteria for classification as a mechanism-based inactivator, the kinetic scheme for inactivation and the calculation of the relevant kinetic constants describing inactivation will be presented. Several examples of mechanism-based inactivation of human P450s will be presented where the site of modification, either heme moiety or apoprotein, and the identity of the reactive intermediate are known. Recent advances in trapping procedures and methods for the identification of reactive intermediates will be presented. The clinical significance of inactivating human P450s in drug safety will be discussed.

3:10 35 Structure and function of cytochrome P450 enzymes: Dynamics of catalytic steps in oxidation of drugs and model substrates
F. Peter Guengerich, f.guengerich@vanderbilt.edu, Christal D. Sohl, Emre M. Isin, and Robert L. Eoff, robert.l.eoff@vanderbilt.edu. Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, 2200 Pierce Avenue, 638 Robinson Research Bldg, Nashville, TN 37232-0146

Several cytochrome P450 (P450) enzymes involved in the biotransformation of drugs have been examined in regard to kinetics of individual steps (esp. 1A2, 2A6, 3A4). The results indicate a mixture of rapid events (e.g., binding and release of substrate) and some that are unexpectedly slow (substrate rearrangement). The slower events, when they occur (in the P450s with the larger sites), are sequential as opposed to parallel with other events. The kinetic complexity of the P450substrate interactions is viewed as one contributor to the ligand cooperativity seen with some P450s. Another contribution is structural, in that P450 1A2 does not show cooperativity with one substrate that fills most of the active site (beta-naphthoflavone) but does with smaller ligands. The nature of the ligands is an issue in that polycyclic aromatic hydrocarbons show positive cooperativity, possibly because of the potential to stack, but other small non-aromatic ligands show opposite cooperativity patterns.

4:00 36 What do industrial medicinal chemists need to know about cytochrome P450?
Ronald E. White, ronald.white@spcorp.com, Drug Metabolism, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033-1300

Metabolism by cytochrome P450 enzymes is the single most important type of clearance of drugs from the human body, and several important adverse clinical pharmacokinetic phenomena are corollaries of this fact. These include large individual variability, autoinduction, drug-drug interactions and covalent binding of P450-generated reactive metabolites to proteins and DNA. Therefore, design of practical clinical medicines must take account of these features of P450-mediated metabolism to create molecules for clinical development that are optimized with respect to pharmacokinetics. The chemical, biochemical and biological basis for these phenomena will be discussed and practical approaches to anticipating, detecting and remediating them during drug design presented. Special attention will be given to the generation of reactive intermediates and metabolites, which can be attributed to the rich oxidative reaction manifold of the P450 iron-oxo enzyme intermediate. Finally, the current strategies for avoiding their occurrence in clinical candidates will be critiqued.

WEDNESDAY MORNING

COMP - Drug Discovery
Sofitel Orleans
Irache Visiers, Organizer; Min Wu, Presiding
8:00 300 A comparative study of human beta-2 adrenergic GPCR theoretical models and crystal structure: The applicability for virtual screening
Hao Tang, tangh@email.unc.edu1, Xiang S. Wang, xswang@email.unc.edu1, and Alexander Tropsha, alex_tropsha@unc.edu2. (1) Laboratory for Molecular Modeling, University of North Carolina at Chapel Hill, School of Pharmacy, Chapel Hill, NC 27599, (2) Laboratory for Molecular Modeling, School of Pharmacy, University of North Carolina at Chapel Hill, CB # 7360, Beard Hall, School of Pharmacy, Chapel Hill, NC 27599-7360

The recently determined crystal structures of human beta2-adrenergic receptor (beta2AR) make it possible to conduct a retrospective study on the theoretical modeling of beta2AR, and GPCRs in a broad sense, with the reference to crystal structures. Theoretical models from five group (i.e. Vriend, Sali, Skolnick, Lybrand and Goddard), together with two GPCRs crystal structures (beta2AR and rhodopsin), have been employed to conduct a systematic study on the structural similarity and capacity for virtual screening. As expected, homology models are dissimilar to b2AR crystal structure (TMs backbone RMSD 2.25Ǻ ~ 3.19Ǻ) but proximate to bovine rhodopsin. In comparison, de novo models are more divergent from both b2AR and rhodopsin (TMs backbone RMSD > 3.0Ǻ). In the virtual screening of known b2AR ligands from WDI database using Glide, AutoDock4 and eHiTS, Lybrand's de novo models perform better than crystal structure in recovering 13 agonists and have comparable capacity for 13 antagonists.

8:25 301 Discovery of novel human histamine H4 receptor ligands by large-scale structure-based virtual screening
Róbert Kiss, r.kiss@richter.hu1, Béla Kiss1, Béla Noszál, nosbel@hogyes.sote.hu2, András Falus2, and György M. Keserû, gy.keseru@richter.hu1. (1) Gedeon Richter Plc, Gyömrõi út 19-21, Budapest, H-1103, Hungary, (2) Semmelweis University, Budapest, H-1089, Hungary

A structure-based virtual screening (SBVS) was conducted on a ligand-supported homology model of the human histamine H4 receptor (hH4R). More than 8.7 million 3D structures derived from different vendor databases were investigated by docking to the hH4R binding site using FlexX. A total of 255 selected compounds were tested by radioligand binding assay, and 16 of them possessed significant [3H]histamine displacement. Several novel scaffolds were identified that can be used to develop selective H4 ligands in future. As far as we know, this is the first SBVS reported on H4R representing one of the largest virtual screens validated by the biological evaluation of the virtual hits.

8:50 302 Discovery of novel antagonist chemotypes to the melanin concentrating hormone receptor, a class A GPCR
Claudio N. Cavasotto, Claudio.N.Cavasotto@uth.tmc.edu, School of Health Information Sciences, University of Texas Health Science Center at Houston, 7000 Fannin Ste. 860B, Houston, TX 77030-5400

The advances of the structural genomics initiatives have rendered comparative or homology modeling more important than ever, since it constitutes a bridge between the sequence and the structural realms. The ligand-steered homology modeling method in presented, in which the knowledge of existing ligands is explicitly used to model the binding site through a docking-based stochastic global energy optimization procedure. The structural modeling approach was applied to the Class A GPCR Melanin Concentrating Hormone Receptor 1 (MCH-R1), a protein known to be linked to obesity. The models thus generated were used in a structure-based virtual screening followed by biological evaluation. Top-ranking molecules were experimentally evaluated, and six out of 129 compounds were found to be active with Ki values in the low micromolar range, showing a hit enrichment rate of more than 10-fold compared to high-throughput screening.

9:15 303 Novel scoring metric for enhancing the prediction of ligand binding mode
Matthew E. Tonero, toneroma@msu.edu1, Mária I. Závodszky, zavodszk@msu.edu1, and Leslie A. Kuhn, KuhnL@msu.edu2. (1) Department of Biochemistry & Molecular Biology, Michigan State University, 502C Biochemistry Building, East Lansing, MI 48824-1319, (2) Departments of Biochemistry & Molecular Biology and Computer Science & Engineering, Michigan State University, 502C Biochemistry Building, East Lansing, MI 48824-1319

Our goal is to improve prediction of ligand binding modes in virtual screening, which is essential to accurately define the interactions used to predict binding affinity. For training, a set of poses was generated with known ligand docking RMSD values relative to the crystallographic pose, for a set of diverse complexes. A scoring function was formed by selecting a linear combination of protein-ligand interaction terms, then training the terms' weights to fit -1/RMSD. This metric provides large-magnitude scores for nearly correct poses, while assigning small scores to poses offset by >2 Å RMSD. This creates a funnel-like scoring landscape and new insights into the terms most useful for predicting binding mode. Using this scoring function, SLIDE selected dockings within 2 Å RMSD of the crystallographic position for 61% of the ligands in 100 protein complexes; quick energy minimization resulted in refining 53% of these dockings to ≤ 1 Å RMSD.

9:40 Introductory Remarks
9:50 304 Can quantum mechanical energies be used as scoring for protein docking?
Art E. Cho, artcho@korea.ac.kr, Department of Bioinformatics and Biotechnology, Korea University, Jochiwon-Eup, Yeongi-Gun, Chungnam, South Korea

In protein docking, scoring is one of the fundamental ingredients. Along with search algorithms, it is the other half of the essential parts of docking that generates predictions for binding mode of protein-ligand complexes. Various scoring functions for docking have been developed and implemented in a number of programs over the years. Most of the scoring functions are based on physical/chemical energy functions, but incorporate some empirical/experimental parameters, which are often fine-tuned with “training sets”. Furthermore, some programs adopt motif-based scoring components, which are modeled through elaborate molecular dynamics or quantum mechanical calculations. Although it is generally accepted that quantum level calculations give us the most detailed description of protein-ligand binding, aforementioned scoring schemes were concocted to reduce the computational demand so that the program can be used in fast docking environment. In this talk, we discuss development of a protocol which utilizes quantum mechanical energy as scoring for docking. We then present the test of this idea on a number of examples grouped in several categories. The results suggest that for certain classes of proteins such idea can be useful.

10:15 305 Novel detection strategy for drug discovery using Shape Signatures and the subtype selective engineered nuclear hormone biosensors
Izabela Hartman, ihartman@princeton.edu1, Alison R. Gillies1, Sonia Arora2, Christina Andaya2, Nitya Royapet1, William J. Welsh2, David W. Wood, dwood@princeton.edu1, and Randy J. Zauhar3. (1) Departments of Chemical Engineering and Molecular Biology, Princeton University, Engineering Quadrangle, A-215 Olden St., Princeton, NJ 08544, (2) Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, UMDNJ-RWJMS, Piscataway, NJ 08854, (3) West Center for Computational Chemistry and Drug Design and Department of Chemistry & Biochemistry, University of the Sciences in Philadelphia, 600 S 43rd street, Philadelphia, PA 19104

The superfamily of nuclear receptors (NR) contains a wide variety of proteins which are linked to the development of common diseases including cancer, obesity and neurodegenerative disorders. Their rapid drug-enzyme complex analysis is crucial in development of novel pharmaceuticals. This presentation shows a unique strategy for fast study of large databases of potential therapeutical compounds by joining computer aided drug design methods including Shape Signatures, a ray-tracing based screening method, docking as well as novel nuclear hormone biosensors developed in-house. The subtype selective engineered chimeric enzymes acting essentially as highly sensitive switches were used for detection of agonist's and antagonist's binding including weak van der Waals interactions. The case study will be discussed here including a comparison of the results to mammalian cell-based assays.

10:40 306 Virtual screening strategies toward the design of novel anthrax toxin lethal factor inhibitors
Ting-Lan Chiu, tlchiu@umn.edu1, Elizabeth A. Amin, eamin@umn.edu1, Anastassia Sorkin, sorki005@umn.edu2, Derek Hook, hookx017@umn.edu3, and Michael A. Walters, walte294@umn.edu3. (1) Department of Medicinal Chemistry, University of Minnesota, 717 Delaware St SE, Minneapolis, MN 55414, (2) Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455-0431, (3) Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St SE, Minneapolis, MN 55414-2959

Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. The lethal factor (LF) enzyme is secreted by B. anthracis as part of a tripartite exotoxin and is chiefly responsible for anthrax-related cytotoxicity. As LF can remain in the system for weeks after antibiotics have eradicated B. anthracis from the body, the preferred therapeutic modality is the administration of antibiotics together with an effective LF inhibitor. Such inhibitors must not only bind strongly to the receptor but must also possess excellent ADMET profiles. Published crystal structures of LF with bound inhibitors provide valuable insight into binding modes. In addition, extensive research carried out in academic and industrial laboratories yields many useful rules-of-thumb for ADMET profiling. In this work, all the above resources are applied to create binding filters based on molecular modeling techniques such as docking, pharmacophore mapping and topomeric searching. In addition, common ADMET filters such as reactive group filtering, Lipinski's and Veber's rules, etc., together with modern in silico ADMET-related property prediction techniques, are applied to facilitate compound profiling and prioritization. Together with experimental high-throughput screening of compound libraries at the University of Minnesota's Institute for Therapeutics Discovery and Development (ITDD), the binding and ADMET filters are used to narrow the search space of novel anthrax lethal factor inhibitors from millions of compounds in our databases to dozens of potential leads.

11:05 307 Virtual screening to identify novel Dengue virus inhbitors
Paul C. Sanschagrin, sanschag@schrodinger.com1, Michael Podvinec2, Tobias Schmidt2, Sebastian Sonntag3, Siew Pheng Lim3, Torsten Schwede2, and Peter S. Shenkin, shenkin@schrodinger.com1. (1) Schrödinger Limited Liability Company, 120 West 45th Street, New York, NY 10036, (2) Swiss Institute of Bioinformatics and University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland, (3) Novartis Institute for Tropical Diseases, 10 Biopolis Road, Chromos #05-01, 138670 Singapore, Singapore

Dengue fever, a neglected disease, is a viral infection found in tropical and sub-tropical regions which can cause fever, severe joint pain, hemorrhage and shock, and, in the worst cases, death. Being endemic in more than 100 countries on five continents, Dengue is becoming a major international public health concern. To identify new potential drug leads, a database of 6 million purchasable compounds was screened using the Glide Virtual Screening Workflow on a mixture of cluster and grid computing resources. Further post-processing and selection yielded a list of 200 compounds to assay, of which 24 were active with IC50s ranging from 2 to 25 uM. Prior to this work, very few ligands were known, with none having IC50s better than 50 uM. Details of the workflow and further work involving Phase pharmacophore searching and Canvas similarity-based searching to identify additional potential leads will be presented.

WEDNESDAY MORNING

MEDI - Co-crystals and Crystal Engineering of Pharmaceuticals
Pennsylvania Convention Center 204 C
Nicholas A. Meanwell, Organizer
8:30 Introductory Remarks
8:40 271 The role of co-crystals in pharmaceutical science
Michael J. Zaworotko, xtal@usf.edu, Department of Chemistry, University of South Florida, 4202 E Fowler Ave, CHE 205, Tampa, FL 33620-5250

The emerging field of crystal engineering facilitates the generation of a wide range of new crystal forms of compounds without the need to invoke covalent bond breakage or formation, i.e. it enables discovery of new compositions of matter even for long known molecules that would otherwise be difficult to patent and fine tune in terms of physical properties. This contribution will focus upon the role of cocrystals in pharmaceutical science with emphasis upon the following:

- A historical perspective of this long known but little studied class of compounds;

- How to design co-crystal formers using crystal engineering and prepare them using “green” methodologies;

- Examples of new co-crystals that include some long known natural products and how they fine tune physical properties of clinical relevance;

- The use of cocrystals for synthesis of new molecular species, i.e. cocrystal-controlled solid state synthesis.

9:20 272 Pharmaceutical co-crystals in action
Matthew L. Peterson, TransForm Pharmaceuticals, 29 Hartwell Avenue, Lexington, MA 02421

The composition of a pharmaceutical formulation and the process by which a dosage form is made can dramatically affect the performance of a resulting drug product. Pharmaceutical co-crystals are becoming important materials for the improvement of the physico-chemical and in vivo performance of pharmaceutical compounds. Enhancements in crystal engineering of pharmaceutical substances and characterization capabilities have increased the drive to translate understanding of crystal form into rational formulation design. Two key aspects of innovation in dosage form design are (1) the discovery and selection of the right crystal form of the drug, and (2) the ability to study materials through manufacture, storage and use of a product. The latter includes the study of interactions of formulations with simulated gastrointestinal fluids, especially in the case of oral formulations of water-insoluble compounds. In this presentation, examples will be presented from the development of pharmaceutical co-crystals into orally bioavailable compositions.

10:00 273 Serendipity in drug development: Discovery of and development of stable co-crystals
Narayan Variankaval, Process Research, Merck Research Laboratories, P.O. Box 2000, Rahway, NJ 07065

This presentation will present the serendipitous discoveries of crystal forms in Merck and their implications in drug development. Two cases will be discussed - (a) crystalline HCl salts of an MC4R agonist and (b) co-crystalline complexes of a PDE-IV compound with tartaric acid and other dicarboxylic acids. In each case, emphasis will be placed on the nature of the isolation process and, more importantly, structure-property-function relationships that enabled these forms of the active ingredient to be successfully formulated into drug products. In some of these cases, crystal structures were solved either from single-crystals or from high resolution powder diffraction data using simulated annealing algorithms. The role played by serendipity in a time of high-throughput approaches for crystal form screening will be highlighted throughout.

10:40 274 Synthesis and applications of pharmaceutical co-crystals: A materials science view
Paul A. Meenan, Groton/New London Laboratories, Pfizer Inc, 558 Eastern Point Road, Groton, CT 06340

The field of co-crystals has elicited significant interest in the pharmaceutical industry recently with the potential to utilize this technology as means of enhancing physicochemical properties such as solubility and dissolution; in addition to enhancements to particle properties that could aid drug product development, .e.g. improving both chemical and physical stability and indeed as a method to induce crystallization of materials that traditionally would have been isolated as an oil or an amorphous material. There is also considerable ongoing debate as to the theoretical definition of a co-crystal, how a co-crystal can be reliably synthesized, manufactured and characterized, coupled with the intellectual properties ramifications therein. This presentation will outline some of our recent research efforts (in-house & external) into the synthesis of co-crystals, and will outline different techniques that can be utilized to characterize co-crystals.

11:20 275 Co-(operative?)-crystal structures
Jack Gougoutas1, John DiMarco2, Michael A Galella2, and Mary F. Malley, mary.malley@bms.com3. (1) Department of Crystallography, Bristol-Myers Squibb Company, P.O. Box 4000, Princeton, NJ 08543-4000, (2) Analytical R & D, Bristol-Myers Squibb Research and Development, PO Box 4000, Princeton, NJ 08543-4000, (3) Department of Analytical R & D, Bristol-Myers Squibb, PO Box 4000, Princeton, NJ 08543-4000

Most of the ~390,000 crystal structures described in the latest release of the Cambridge Structural Database (2008, as529be) were assembled/grown in some suitable solvent(s). Nevertheless, about half of these "small-molecule" structures crystallized in "NEAT" arrangements assembled ONLY from the "compound of interest" - sometimes in more than one conformational, tautomeric or stereochemical form within the lattice.

The other half of the known structures in the database contain one or more "extraneous chemical components/impurities" as an INTEGRAL and NECESSARY part of the observed crystal structure of the "compound of interest".

Although water and/or solvent(s) of crystallization are the most common "extraneous lattice components" (hydrates/solvates), many examples demonstrate that stable 3d arrangements/crystal structures can be assembled with the aid of a surprisingly wide variety of "extraneous chemical compounds" (co-crystals). If Nature co-operates in our designs, some choices of "extraneous components" may lead to improved physical and/or biological properties of novel co-crystals.

WEDNESDAY MORNING

TOXI - Environmental and Human Health Impacts of Nanomaterials
Loews Regency B
Agnes B. Kane, Robert Hurt, Organizers
8:30 89 Environmental and human health impacts of nanomaterials
Agnes B. Kane, Agnes_Kane@Brown.edu, Department of Pathology & Laboratory Medicine, Brown University, 70 Ship Street, Box G-E5, Providence, RI 02912

It is now recognized that the recent world-wide investment in new nanomaterials should be accompanied by parallel efforts to explore and understand their potential impacts on human health and the environment. By virtue of their small size, nanomaterials may penetrate biological membranes, enter cells, carry high concentrations of absorbed molecules, or show elevated surface reactivity relative to their macroscopic counterparts. This symposium introduces the emerging field of nanotoxicology from an interdisciplinary perspective. The ultimate goal is to identify the specific material features (size, shape, surface chemistry, purity) that are the underlying causes of toxicity. The long-term promise of this approach is to learn how to modify synthesis or purification procedures to fabricate “green” nanomaterials in order to exploit their unique properties for applications in environmental sensing and remediation and in nanomedicine.

8:45 90 Biological activity of mineral fibers and carbon particulates: Implications for nanoparticle toxicity and the role of surface chemistry
Prabir K. Dutta, Dutta.1@OSU.edu, Department of Chemistry, Ohio State University, 100 W 18th Avenue, Columbus, OH 43210

In this presentation, we will summarize our work on the correlations between biological activity and physicochemical characteristics of minerals and particulates, including the biological response (oxidative burst), mutagenicity and the chemical reactivity (Fenton reaction) of zeolite minerals and oxidative stress and inflammatory responses of carbon particulates. Zeolites, with well defined crystal structures serve as model systems for asbestos and other toxic minerals. For assessment of biological response, phagocytosis as well as the oxidative burst has been studied. For determining chemical reactivity, we have focused on the ability of the iron-exchanged forms of the zeolites to produce hydroxyl radicals from H2O2 (Fenton reaction). Mutagenic potential of erionite and mordenite and how this mutagenic potential is modulated by iron has been examined. The impact of carbon-based particulate physicochemical characteristics upon their ability to induce oxidative stress and inflammatory responses has been studied. Internalization of particulates by freshly isolated and differentiated human monocyte-derived macrophages (MDM) is being examined. To determine the impact of particulate physicochemical characteristics upon their inflammatory potential, inflammatory endothelial adhesion molecule expression by immunofluorescence flow cytometry is being examined. Fenton activity of particulates is being assayed by measurement of their ability to catalyze the decomposition of hydrogen peroxide to hydroxyl radicals by spin trapping with 5,5-dimethylpyroline-N-oxide (DMPO).

9:30 91 Cellular and subcellular interactions with nanoparticles
Galya Orr, Galya.Orr@exchange.pnl.gov, Chemical Structure & Dynamics, Pacific Northwest National Laboratory, PO Box 999, MSIN: K8-88, Richland, WA 99352

Widespread commercial applications of nanotechnology will increase potential human exposure to submicron and nanoscale particles by inhalation into the lungs. The mechanisms driving cellular and subcellular interactions of nanoparticles with target cells in the lung are unknown. We have developed novel imagining techniques to study the internalization pathway of individual amorphous silica particles following one particle at a time. This internalization pathway depends on particle surface charge and integrity of the cytoskeleton of lung alveolar epithelial cells. These studies have identified a novel retrograde transport pathway leading to particle recruitment, internalization, and toxicity in polarized epithelial cells with surface microvilli. This research was supported by a U.S. Environmental Protection Agency STAR grant RD 833338 and the Environmental Biomarkers Initiative at the Pacific Northwest National Laboratory.

10:15 Intermission
10:30 92 Potential adverse human health impacts of nanomaterials
Günter Oberdörster, Günter_Oberdörster@urmc.rochester.edu, Department of Environmental Medicine, University of Rochester School of Medicine & Dentistry, 575 Elmwood Avenue, Box EHSC, Rochester, NY 14642

Numerous epidemiological studies have shown that acute adverse health effects are associated with exposures to ambient airborne particles. These effects occur mostly in sensitive parts of the population such as the elderly with a compromised cardiorespiratory system. We hypothesize that ultrafine particles (particle size below 0.1 µm) are one potential source causing these effects. In addition, a new source of exposure to particles below 100 nm in size engineered nanoparticles has become a cause for concern, giving rise to the emerging field of nanotoxicology. The propensity of nanoparticles of different shapes (e.g., spheres, tubes, rods), different chemistries (e.g., metals, semiconductors, carbon) and different surface characteristics (coating, charge, porosity) to translocate from the site of deposition in the respiratory tract to extrapulmonary organs such as heart, liver, bone marrow and brain is being studied. Examination of the influence of physicochemical properties of nanoparticles on their effects and biokinetics is the ultimate objective of these studies. Effects and underlying mechanisms of translocated nanoparticles (e.g., cellular oxidative stress) are evaluated in a multidisciplinary team approach. This research is supported by a U.S. Department of Defense MURI grant FA9550-04-1-0430 and U.S. Environmental Protection Agency Particulate Matter Center grant RD 83241501.

11:15 93 Designing nanomaterials for environmental health and safety
Robert Hurt, Robert_Hurt@Brown.edu, Division of Engineering, Brown University, 146 Hope Street, Box D, Providence, RI 02912

Nanotechnology has been given a unique “window of opportunity” to develop methods for managing EHS concerns before its products become truly widespread in the marketplace. In contrast to many traditional pollutants, nanomaterials are high-technology products under continual development and evolution. Their synthesis, surface modification, processing, release and environmental transformation, and biological impacts form a cause-effect continuum that offers many opportunities for intelligent intervention on behalf of safety. Short term risks may be reduced through materials and formulation-based strategies that do not require complete quantitative understanding of the relationship between exposure and adverse health impacts. These strategies typically target exposure or bioavailability of known toxicants and are devised through analogy with existing pollutants. Longer term risk management requires parametric and mechanistic studies on material libraries that can guide the development of current and future nanomaterials toward intrinsic safety. This talk uses carbon nanotubes as an example material family to discuss the role of individual material features (hydrophobic graphenic surface, functional groups, amorphous carbon, metals, and aggregate state), our current understanding of environmental transformations and biopersistence, and opportunities for safer formulation. This research was supported by grants from the National Science Foundation (NSF DMI-05066) and the National Institutes of Health (R01 ES016178 and P42 ES 013550).

WEDNESDAY MORNING

MEDI - Structure- and Ligand-Based Drug Design
Pennsylvania Convention Center 204 A&B
Michelle L. Lamb, Adriano D. Andricopulo, Organizers
9:00 265 Efficient lead optimization guided by free-energy calculations
William L Jorgensen, william.jorgensen@yale.edu, Department of Chemistry, Yale University, New Haven, CT 06520-8107

Drug development is being pursued through computer-aided structure-based design. For de novo lead generation, the BOMB program builds combinatorial libraries in a protein binding site using a selected core and substituents, and QikProp is applied to filter all designed molecules to insure that they have drug-like properties. Monte Carlo/free-energy perturbation simulations are then executed to refine the predictions for the best scoring leads including ca. 1000 explicit water molecules and extensive sampling for the protein and ligand. FEP calculations for optimization of substituents on an aromatic ring and for choice of heterocycles is now common. Alternatively, docking with Glide is performed with the ZINC database to provide leads that are then optimized via the FEP-guided route. Successful application has been achieved for HIV reverse transcriptase and macrophage migration inhibitory factor (MIF); micromolar leads have been rapidly advanced to extraordinarily potent inhibitors.

9:35 266 Integrating bioprospection and structure based drug design against tropical infectious diseases
Glaucius Oliva, oliva@ifsc.usp.br1, Rafael V. C. Guido, rvcguido@ifsc.usp.br1, Otavio H. Thiemann1, Adriano D. Andricopulo, aandrico@if.sc.usp.br1, Paulo C. Vieira2, Joao B. Fernandes2, Maria Fatima GF. Silva2, and Arlene G. Correa2. (1) Institute of Physics of Sao Carlos, University of Sao Paulo, Av. Trabalhador Saocarlense, 400, Sao Carlos, 13560-970, Brazil, (2) Department of Chemistry, Federal University of Sao Carlos, Sao Carlos, Brazil

Infectious diseases continue to impede social and economic progress in the developing countries, disproportionately affecting poor and marginalized populations. The available chemotherapy is extremely limited with drugs that were predominantly developed in the first half of last century, presenting significant risk due to side effects. Additionally, the widespread upsurge of parasite strains resistant to the available drugs has been alarming, whereas the development of new alternatives for treatment and prevention has been minimal, therefore representing a challenge for the Medicinal Chemistry of developing countries. In this talk we will present our integrated experimental approach to this goal, which includes cloning and overexpression of parasitic enzymes, their crystallization and X-ray crystallography studies, rational drug design, synthesis and extensive screening and testing of both synthetic and natural products compounds obtained from the Brazilian biodiversity. In the past years, a dozen different proteins from tropical parasites had their structures elucidated in our lab, related to Chagas disease, leishmaniasis, schistosomiasis, sleeping sickness, nagana and malaria. Also, in an on-going program to screen natural products libraries in the search for new potential inhibitors, a series of promising compounds were identified and subsequently improved by structure based drug design, QSAR techniques and conventional and combinatorial chemistry. We will conclude by focusing on the enzyme GAPDH from T.cruzi, of which we have 10 different crystal structures, offering a unique view of the catalytic mechanism and inhibitory pathways of this enzyme.

10:10 267 Virtual screening for drug discovery
Diane Joseph-McCarthy, Computational Science, Infection, AstraZeneca, 35 Gatehouse Drive, Waltham, MA 02451

Ligand-based and target-based virtual screening techniques are commonly used to generate new leads during the drug discovery process. Where possible it is beneficial to employ both approaches to a given target. Case studies involving the use of ligand-based methods, target-based methods, and a combination of the two will be presented. The results in terms of hit rates and the types of hits obtained will be compared. Various docking and scoring methods and their applicability to different types of targets and small molecules will also be discussed.

10:45 Intermission
10:55 268 Ligand recognition by thyroid hormone and estrogen receptors: Structural studies and molecular dynamics simulations
Leandro Martínez1, Milton T. Sonoda2, Munir S. Skaf1, and Igor Polikarpov, ipolikarpov@if.sc.usp.br3. (1) Universidade Estadual de Campinas - UNICAMP, (2) Universidade de São Paulo, (3) Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, SP, 13560-970, Brazil

Nuclear receptors are ligand-inducible transcription factors that share structurally related DNA-binding (DBD) and ligand-binding (LBD) domains. Hormone binding to nuclear receptors is mediated by repositioning of helix 12 and conformational changes in LBDs, which have profound effects on NR interactions with the cognate DNA response elements and co-regulating proteins, hence provoking profound changes in gene transcription activation and repression. Mechanistic details of this complex molecular event continue to be elusive. To shed more light on molecular basis of NR:ligands interactions we undertook studies of structure and dynamics of thyroid hormone (TR) and estrogen (ER) nuclear receptors. Here we will discuss our recent crystallographic results on TR complexes with TRƒ"-selective ligands and molecular dynamics simulations of ligand dissociation from ER and TR.

11:30 269 Comparison of the rhodopsin and beta2 adrenergic receptor structures as templates for GPCR modeling
Andrew J. Tebben, andrew.tebben@bms.com, Percy Carter, Qihong Zhao, and Roy Kimura. Bristol-Myers Squibb Pharmaceutical Research Institute, P.O. Box 4000, Princeton, NJ 08543-4000

Much of the GPCR modeling undertaken in the past several years has been derived from the rhodopsin crystal structure. While this has proven to be a viable template structure, the models often require significant manipulation to accommodate ligands in the binding site and produce results consistent with mutagenesis and SAR studies. Recently a new structure has become available, the ƒ"2 adrenergic receptor crystallized with the inverse agonist carazolol. It is potentially a more relevant template as it has higher homology to many receptors of interest and the size of the co-crystallized ligand is closer to that of many small molecule GPCR agonists and antagonists. To assess the utility of this new structure, models have been built from both it and the rhodopsin template. These models were evaluated in the context of receptor mutagenesis and SAR. Based on these results, the ƒ"2 adrenergic template appears to be superior, particularly for antagonist modeling.

12:05 270 Design, synthesis and evaluation of new antifolates for malaria
Jose Daniel Figueroa-Villar, figueroa@ime.eb.br1, Marta Gonçalves dos Santos, martags@ime.eb.br1, Luzineide Wanderley Tinoco, lwtinoco@nppn.ufrj.br2, Cristiane Diniz Ano Bom1, Tanos Celmar Costa França1, and Leandro Araújo de Lima1. (1) Department of Chemistry, Medicinal Chemistry Group, Military Institute of Engineering, Praça General Tiburcio 80, Rio de Janeiro, 22290-270, Brazil, (2) Núcleo de Pesquisas de Produtos Naturais, Federal University of Rio de Janeiro, Centro de Ciências da Saúde, Bloco H, Rio de Janeiro, 21941-590, Brazil

Malaria is one of the most dangerous parasitic diseases caused by protozoan species, killing about a million people worldwide every year. One of the major problems regarding malaria chemotherapy is resistance development as a consequence of drug pressure on the parasites. Also, effective antimalarial drugs are expensive for treatment of patients in third world countries. In this work we have used molecular modeling methodologies to design and evaluate cheap new 2,4-diaminopyrimidines as inhibitors of mutant Plasmodium falciparum dihydrofolate reductase (PfDHFR). The planned compounds were synthesized and tested as selective ligands for PfDHFR using NMR and enzyme kinetics. The most effective compound was able to kill in vitro 94% of the parasites at a 3,2 nM concentration, thus being 5 times more effective than pyrimethamine on pyrimethamine-resistant P. falciparum.

 

 

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