48th ASH™ Annual Meeting and Exposition
December 9-12, 2006

Orange County Convention Center
Orlando, Florida

Special Interest Sessions

Training Program Directors Workshop/Business Meeting

Thursday, December 7, 2:00 p.m. – 8:00 p.m.

This year marks ASH's third annual workshop for training program directors, an event where these colleagues can learn from outside experts and from each other.

A plenary session on ACGME and RRC requirements as well as two mini-workshops on developing and maintaining fellow educational portfolios and program improvement tools and measures will provide outstanding opportunities for training program directors to address the most pressing issues facing them and share best practices in critical areas. Additionally, program directors who complete this program will be eligible for AMA PRA Category 1 Credit TM.

To facilitate the workshop, we are asking participants to provide us with examples of their "best practices" for fellows' educational portfolios and program assessment tools and measures. Please e-mail your "best practices" to training@hematology.org. By sharing these different approaches for meeting ACGME and RRC requirements, we hope this session will help everyone achieve their individual educational and regulatory goals most effectively.

Instead of holding a training program directors lunch later in the week, we will conclude the workshop with a reception and directors' dinner during which the annual business meeting will be held. Dinner will be provided. Please note the date and the new combination of the Training Program Directors Workshop and Business Meeting and make your travel plans accordingly.

Trainee Simultaneous Didactic Sessions

During Saturday and Sunday of the annual meeting, two simultaneous didactic sessions will occur.

Saturday, December 9, 11:15 am – 12:15 pm

• How to Write a Paper for Publication in a Journal  
  Sanford Shattil, MD, Editor-in-Chief, Blood, University of California – San Diego, San Diego, CA
  
  
• Applying Evidence (Even If It Is Lacking) to Clinical Practice
  Mark Crowther, MD, MSc, St. Joseph’s Hospital, Hamilton, Ontario Canada
  Richard Lottenberg, MD, University of Florida, Gainesville, FL

Sunday, December 10, 11:15 am – 12:15 pm

• Mentors and Their Messages
  Edward Benz, Jr., MD, Dana-Farber Cancer Institute, Boston, MA
  
  
• How to Land your Perfect Job in Hematology
  Robert F. Todd, III, MD, PhD, University of Michigan Medical School, Ann Arbor, MI
  Mark Ramirez, MD, Montefiore Medical Center, Bronx, NY

Seating is limited; therefore, attendees are strongly encouraged to arrive early. No additional persons will be allowed in the rooms once the sessions are filled.

Please note that this event is open only to ASH Associate members and non-members in training wearing trainee meeting badges.

Practice Forum

Saturday, December 9, 6:00 p.m. – 7:30 p.m.

Title: Pay-for-Performance: Are You Ready?

Chair: Robert Weinstein, MD, Chair, ASH Committee on Practice, University of Massachusetts Medical Center, Worcester, MA 

ASH Representatives:

Ellen Riker, Executive Vice President of MARC Associates and Government Relations Consultant to ASH, Washington, DC

Mila N. Becker, Esq., Director of Government Relations and Practice, American Society of Hematology, Washington, DC
Legislative Update and Report on ASH's Advocacy Efforts

Pamela Ferraro, Practice Advocacy Manager, American Society of Hematology, Washington, DC
Practice Update

The ASH Committee on Practice sponsors this forum to address current topics important to the practicing hematologist. The program will feature presentations on hematology practice issues of interest to state societies. Of particular interest will be updates on the current legislative environment, pay-for-performance, and what these mean for your practice.

A representative from the National Quality Forum (NQF) will discuss quality and reporting and how that relates to the trend towards pay-for-performance. A panel of state society presidents, moderated by Dr. Robert Weinstein, will discuss the impact on practices now and in subsequent years.

ASH representatives Mila Becker, Pamela Ferraro, and Ellen Riker will provide a report about the Society's practice-related advocacy efforts throughout the year and updates on legislation and regulations that will affect reimbursement for hematologists and establish new performance measurement requirements.

A reception sponsored by Genentech BioOncology/Biogen Idec will follow the program.

Promoting Minorities in Hematology

Saturday, December 9, 6:30 p.m. – 9:00 p.m.

ASH invites all interested meeting attendees to this presentation highlighting training and research opportunities for minorities underrepresented in hematology. The event will begin at 6:30 p.m. with a reception and poster presentations by students participating in the NHLBI Minority Research Supplement. The research of the 2006 Minority Medical Student Award Program participants will be featured during a series of oral presentations from 7:15 p.m. to 8:30 p.m. In addition, the new ASH-AMFDP – a partnership between ASH and the Harold Amos Medical Faculty Development Program (AMFDP) of the Robert Wood Johnson Foundation – will be highlighted. Representatives from the NHLBI, NCI, NIDDK, and NIA will also be in attendance to provide information about their various training and research offerings. The event will conclude by 9:00 p.m. with a buffet dinner and networking session.

Please join us to hear the impressive research presentations of program participants and to learn more about these exciting opportunities.

ASH Grassroots Network Breakfast

Sunday, December 10, 7:00 a.m. – 8:00 a.m.

During 2006, ASH launched several advocacy efforts concerning increasing the NIH budget, physician reimbursement, and support for stem cell research and genetic nondiscrimination legislation. The Grassroots Network Breakfast provides a forum for ASH staff to provide an update on major ASH legislative and regulatory efforts during 2006, and all ASH members interested in becoming involved with the Society's advocacy efforts are invited to come and learn about the issues that will top ASH's 2007 advocacy agenda.

Hematology Course Directors Meeting

Sunday, December 10, 7:00 a.m. – 9:00 a.m.

Join us for a breakfast meeting designed especially for second-year hematology course directors. Speakers will discuss the latest tools and techniques available for teaching a second-year hematology course. We welcome you to share your experiences and exchange information on best practices for teaching hematology. If you are interested in making a presentation at this year's meeting please contact training@hematology.org.

Blood and Beyond: Searching the Scientific Literature Online

Sunday, December 10, 6:00 p.m. – 7:00 p.m.

The explosion of information on the Internet has led to powerful new search technologies to help make order out of chaos. Blood has partnered with Stanford University's HighWire Press to provide robust search capabilities within Blood's online journal site. This session will explore how to use the searching and alerting features in Blood Online to mine the scientific literature. Participants will also be introduced to new searching and automatic alerting features available from the HighWire portal, which allow powerful searching and browsing of hundreds of online journals plus Medline, in addition to other ASH publications hosted on the HighWire portal.

ASH Career Development Lunch

Monday, December 11, 12:30 p.m. – 1:30 p.m.

Two simultaneous career development lunch sessions will provide an intimate venue for trainees to meet with leaders in hematology to discuss professional development issues. ASH has invited a diverse group of researchers and physicians representing the wide array of practice areas within hematology. Careers in clinical, translational, and basic research will be discussed, as well as careers in industry settings and private and clinical practice. A box lunch will be provided. Space is available on a first-come, first-served basis for the first 180 trainees. S eating is limited; therefore, attendees are strongly encouraged to arrive early. No additional persons will be allowed in the rooms once the sessions are filled.

Please note that this event is open only to ASH Associate members and non-members in training wearing trainee meeting badges.

Special Session on the Basic Science of Hemostasis and Thrombosis

Tuesday, December 12, 1:30 p.m. – 5:30 p.m.

This special session was designed to expand the opportunity for exchange and communication among basic scientists in the field of hemostasis and thrombosis. It will highlight the most important basic science contributions in 2006 in each of the four major areas of the field: (1) thrombosis; (2) blood coagulation and fibrinolysis; (3) platelet biology; and (4) structural biology.

In addition to the invited speakers listed, this special session will include a number of oral presentations selected from abstracts submitted to ASH for the annual meeting.

Thrombotic Thrombocytopenic Purpura (TTP) is a life-threatening illness characterized by microangiopathic hemolytic anemia, thrombocytopenia, and widespread microvascular platelet thrombi. Von Willebrand Factor (VWF) cleaving protease activity is markedly reduced in the plasma of most TTP patients, either on the basis of constitutional deficiency or acquired autoantibodies inhibiting protease activity. The responsible protease was identified by both genetic and biochemical approaches as a member of the ADAMTS family of zinc metalloproteinases, ADAMTS13. A large number of ADAMTS13 gene mutations have now been characterized, and appear to account for all cases of familial TTP studied to date. These mutations often lead to a misfolded protein that is poorly secreted, whereas other mutations appear to disrupt protease function. Mice deficient in ADAMTS13 are viable and exhibit normal survival, although VWF-mediated platelet-endothelial interactions are significantly prolonged. Introduction of the genetic background CASA/Rk (a mouse strain with elevated plasma VWF) resulted in the appearance of spontaneous thrombocytopenia in a subset of ADAMTS13-deficient mice and significantly decreased survival. Challenge of these mice with shigatoxin (derived from bacterial pathogens associated with hemolytic uremic syndrome) resulted in a striking syndrome closely resembling human TTP. Surprisingly, no correlation is observed between plasma VWF level and severity of TTP, implying the existence of TTP-modifying genes distinct from VWF. These data suggest that microbe-derived toxins (or possibly other sources of endothelial injury), together with additional genetic susceptibility factors, are required to trigger TTP in the setting of ADAMTS13 deficiency.

James A. Huntington, PhD, University of Cambridge, Cambridge, United Kingdom
ATIII-Factor Xa-Heparin Structure and the Allosteric Mechanism of ATIII Activation

Antithrombin (ATIII) is the most important inhibitor of the coagulation proteases. To allow appropriate blood clotting (hemostasis), ATIII circulates in a conformation which is poorly reactive towards its target proteases. The native state of ATIII is thus permissive of coagulation, and its activation shuts coagulation down. The fine balance between these two activities is critical for life, as too much ATIII activity leads to bleeding, and too little activity causes thrombosis. ATIII is activated by binding to a specific heparin pentasaccharide which alters the conformation of the reactive center loop (RCL). The molecular basis of this activation event lies at the heart of the regulation of hemostasis and accounts for the anticoagulant properties of the low molecular weight heparins. Although several structures of ATIII have been solved, the conformation of the RCL in native ATIII has been obscured by an obligate crystal contact between the RCL of native ATIII and its latent counterpart in crystals of the heterodimer. To obtain crystals of monomeric native ATIII, we engineered a disulfide bond, which prevented the latent conversion, and solved the structure of the variant to 2.75Å resolution. The RCL of monomeric ATIII is shifted ~20Å, and a salt-bridge is observed between the P1 residue Arg393 and Glu237. This contact explains the effect of mutations at the P1 position on the affinity of ATIII for heparin, and also the properties of ATIII-Truro (E237K). The relevance of the observed conformation was verified through mutagenesis studies and by solving structures of the same variant in different crystal forms. The poor inhibitory activity of the circulating form of ATIII is significantly due to the intramolecular contacts involving the RCL, which orient the P1 residue away from attacking proteases. To determine the molecular basis of protease recognition by allosterically activated ATIII, we solved the crystallographic structure of the Michaelis complex between pentasaccharide-bound ATIII and S195A factor Xa. The heparin-induced conformational change in ATIII is required to allow simultaneous contacts within the active site and two distinct exosites of factor Xa (36-loop and the autolysis loop). Together, these structures explain the molecular basis of ATIII activation and protease recognition and, thus, the mechanism of action of the important therapeutic low molecular weight heparins.

Sriram Krishnaswamy, PhD, Children's Hospital of Philadelphia and University of Philadelphia, Philadelphia, PA
Regulation of the Extrinsic and IntrinsicPathways of Coagulation

The VIIa/tissue factor complex (VIIa/TF, Extrinsic Xase) and the IXa/VIIIa complex (Intrinsic Xase) provide redundant pathways for the formation of factor Xa in the coagulation cascade. Initiation of coagulation through the tissue factor pathway following vascular damage results in the formation of Xa and IXaβ . It is factor Xa produced in this step, and its subsequent ability to produce thrombin, that is considered to play the primary role in the initiation phase. IXaβ is considered to be produced in minor amounts by VIIa/TF and plays a lesser role. However, the differential inhibition of Xa, IXaβ, and VIIa/TF by antithrombin III (AT) and tissue factor pathway inhibitor (TFPI) enforces an additional level of regulation that is not necessarily obvious from studying the action of VIIa/TF on its individual substrates. Kinetic studies performed at physiological concentrations of X, IX, TFPI, and AT indicate that IXaβ is the principal active product of the VIIa/TF complex while active Xa is produced at lower amounts and is rapidly consumed. This result, quantitatively accounted for by the measured kinetics of the individual reaction steps, largely reflects the rapid inhibition of Xa by AT while active IXaβ is long-lived. Paradoxically, the Xa-dependent action of TFPI on VIIa-TF is the primary regulator of active IXaβ produced while AT is the primary regulator of the levels of active Xa. The presence of physiological concentrations of factor VIII leads to explosive Xa formation and full consumption of factor X even when steps are taken to effectively inhibit any possible traces of thrombin. Products of the VIIa/TF reaction can rapidly activate factor VIII and further amplify Xa production through the intrinsic Xase. Although the binding of factor VIII to von Willebrand factor (vWF) inhibits the cleavage of factor VIII by Xa, physiologic concentrations of vWF affect sustained Xa formation in a minor way. In contrast, the amplified response through the intrinsic Xase can be abrogated by specific inhibition of the cleavage of factor VIII by Xa. Thus, in such limited reconstituted reaction systems, IXaβ and Xa produced by VIIa/TF in the initiation phase of coagulation are also capable of driving an amplified and sustained response of factor Xa formation through the intrinsic pathway. These ideas provide new perspectives in deciphering the regulated and differential contributions of the extrinsic and intrinsic Xase complexes to thrombus formation following vascular damage.

Andrew Weyrich, PhD, University of Utah, Salt Lake City, UT
Pre-mRNA Splicing Modulates the Thrombogenecity of Platelets

Traditionally, platelets are stereotyped as simple, noncomplex cells with primitive hemostatic responsibilities. However, recent work from our group has demonstrated that anucleate platelets contain a functional spliceosome, an mRNA processing unit that consists of more than 100 proteins and specialized nuclear RNAs. The spliceosomal complex is found in the nucleus of all eukaryotic cells. In response to adhesive signals, however, megakaryocytes distribute their spliceosome into proplatelet extensions and as a result, mature human platelets possess a functional spliceosomal unit. During characterization of the platelet spliceosome, we found pre-mRNA for interleukin-1β (IL-1β) in proplatelet extensions and mature platelets. In response to activating signals, platelets remove non-codeable introns from the pre-mRNA to produce mature IL-1β transcripts. Activated platelets subsequently translate the mature message into IL-1β protein that increases the adhesiveness of human endothelial cells for polymorphonuclear leukocytes. This indicates that de novo synthesis of IL-1β protein contributes to critical inflammatory functions of platelets. In addition to IL-1β, we now know that pre-mRNA splicing events control tissue factor (TF) expression in platelets. In situ studies reveal that TF pre-mRNA is present in the cytoplasm of megakaryocytes and their proplatelet extensions. Freshly isolated human platelets exclusively express TF pre-mRNA, a result that has been reproducible in over 50 healthy volunteers. As platelets adhere to immobilized fibrinogen in the presence of thrombin (0.1 U/ml), TF pre-mRNA is spliced into mature message. Splicing is associated with the rapid and sustained accumulation of protein and increased TF-dependent procoagulant activity in the membranes of activated cells. Splicing of TF pre-mRNA is controlled by cdc2-like kinase 1 (Clk1), a signaling intermediate that was not previously known to operate in platelets. Clk1 is mobilized to focal adhesion points in adherent, spread platelets and immune-captured Clk1 phosphorylates splicing factor 2/alternative splicing factor (SF2/ASF), a rate-limiting spliceosomal component. Neutralization of Clk1 blocks SF2/ASF phosphorylation, TF pre-mRNA splicing, and increases in TF-dependent procoagulant activity in stimulated platelets. In addition, inhibition of Clk1 signaling or TF neutralizing antibodies prevent activated platelets from accelerating plasma clot formation. Together, these studies indicate that platelets can accumulate TF protein via intrinsic pre-mRNA splicing pathways in addition to the well-characterized acquisition of monocyte-derived microparticles. Our studies demonstrate that pre-mRNA splicing provides anucleate platelets with a signal-dependent mechanism for the de novo synthesis of proteins that regulate thrombosis and inflammation. Inhibition of pre-mRNA splicing may be a potential therapeutic target in syndromes of disordered coagulation. Indeed, we have found that pre-mRNA splicing becomes dysregulated in platelets isolated from patients with diagnosed sepsis.

Co-Authors:Hansjörg Schwertz, MD, Neal D. Tolley, MA, and Guy A. Zimmerman, MD, University of Utah, Salt Lake City, UT; Nigel Mackman, PhD, The Scripps Research Institute, La Jolla, CA

Mingdong Huang, PhD, Beth Israel Deaconess Medical Center and Harvard University School of Medicine, Boston, MA
Structure of the Urokinase-Urokinase Receptor Complex

Urokinase plasminogen activator (uPA) and its cellular receptor (uPAR) have received extensive study as one of the two primary endogenous systems that mediate plasminogen activation. They are also involved in other general cellular functions and in subsequent diverse pathophysiological processes, such as tissue remodeling and arteriosclerosis. The uPA binds to uPAR at high affinity (K_d of 0.1–1 nM), thus localizing the generation of plasmin from plasminogen to pericellular regions of a variety of cells. Besides uPA, uPAR is also capable of interacting with several other ligands, including vitronectin, uPAR-associated protein, integrins, and G-protein-coupled receptors. The structural basis underlining uPAR's ability to recognize multiple ligands is uncertain. We have identified the structural mechanisms of uPAR binding with two of its ligands: uPA and the SomB domain of vitronectin. We have solved the crystal structures of (1) the soluble urokinase receptor (suPAR) complexed with the urokinase amino terminal fragment (ATF) and an anti-receptor antibody at 1.9 Å; and (2) suPAR complexed with SomB domain of vitronectin. Three consecutive three-finger fold domains of suPAR pack closely to each other, resulting in a cone-shaped cavity surrounded by these three domains. The cavity has a wide opening (25 Å) and significant depth (14 Å). ATF inserts its growth factor domain into the uPAR cavity and contacts with all three uPAR domains. The structure of suPAR in complex with SomB domain of vitronectin shows that SomB binds at the outer side of uPAR surface. The SomB loop 27 containing a pair of tyrosines (residues 27 and 28) is buried in a cleft form by uPAR 89 and 35 loops from D1 domain. On the other hand, uPAR's Arg91 inserts into a cleft in SomB domain defined by Asp22, Phe13, Tyr28 and forms hydrogen bonds with Asp22. This intertwined interaction leads to high binding affinity between SomB domain and uPAR. These structures provide insight into the flexibility of the urokinase receptor that enables its interaction with a wide variety of ligands.

Lawrence Brass, MD, PhD, University of Pennsylvania, Philadelphia, PA
Minding the Gaps to Promote Thrombus Growth and Stability

Although circulating platelets are not normally in stable contact with each other, they develop such contacts in response to vascular injury. The net result is the formation of a multicellular structure that incorporates a network of narrow gaps and close contacts between the platelets. Platelet activation by collagen or thrombin begins with rapid, usually Ca⁺⁺-dependent, signaling events that activate α_IIb β₃ and allow platelets to adhere to each other via bridges formed by adhesive proteins bound to the integrin. Although a considerable effort has been made to understand the steps that lead to integrin activation, there is now growing evidence that stable thrombus formation depends upon post-aggregation events as well. Outside-in signaling through α_IIb β₃ is one well-known example, but other contributions to thrombus stability depend on the accumulation of secreted or shed ligands in the gaps between platelets. Still others involve the binding of a ligand on the surface of one activated platelet to receptors present on the surface of adjacent platelets. Examples from our own work include the binding of ephrins to Eph receptor tyrosine kinases and the binding of the semaphorin family member, sema4D (CD100), to its receptors CD72 and plexin-B1. Each of these interactions promotes thrombus growth and stability, and interruption of any of them produces phenotypes in which platelet aggregation requires greater agonist concentrations or in which premature disaggregation occurs despite the continued presence of an agonist. An additional class of cell surface proteins that can engage in direct interactions between platelets includes the cell adhesion molecules, PECAM and ESAM. Both of these proteins accumulate at sites of contact between platelets where they would be predicted to act as further cellular glue, supplementing the essential role of α_IIb β₃. Paradoxically, however, loss of PECAM has been shown to promote platelet activation, and loss of ESAM appears to do so as well, suggesting that these molecules play more than one role. In summary, our emerging theme is that the gaps and contact points between activated platelets within a thrombus are the sites of activity that is highly relevant to the “life cycle” of the thrombus.