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Current treatment of toxoplasmosis targets the parasite’s folate metabolism through inhibition of dihydrofolate reductase (DHFR). The most widely used DHFR antagonist, pyrimethamine, was introduced over 60 years ago and is associated with toxicity that can be largely attributed to a similar affinity for parasite and human DHFR. Computational analysis of biochemical differences between Toxoplasma gondii and human DHFR enabled the design of inhibitors with both improved potency and selectivity. The approach described herein yielded TRC-19, a promising lead with an IC50 of 9 nM and 89-fold selectivity in favor of Toxoplasma gondii DHFR, as well as crystallographic data to substantiate in silico methodology. Overall, 50% of synthesized in silico designs met hit threshold criteria of IC50 2-fold selectivity favoring Toxoplasma gondii, further demonstrating the efficiency of our structure-based drug design approach.

Current treatment of toxoplasmosis targets the parasite's folate metabolism through inhibition of dihydrofolate reductase (DHFR). The most widely used DHFR antagonist, pyrimethamine, was introduced over 60 years ago and is associated with toxicity that can be largely attributed to a similar affinity for parasite and human DHFR. Computational analysis of biochemical differences between

Cholesteryl ester transfer protein (CETP) has been identified as a novel target for increasing HDL cholesterol levels. In this report, we describe the biochemical characterization of anacetrapib, a potent inhibitor of CETP. To better understand the mechanism by which anacetrapib inhibits CETP activity, its biochemical properties were compared with CETP inhibitors from distinct structural classes, including torcetrapib and dalcetrapib. Anacetrapib and torcetrapib inhibited CETP-mediated cholesteryl ester and triglyceride transfer with similar potencies, whereas dalcetrapib was a significantly less potent inhibitor. Inhibition of CETP by both anacetrapib and torcetrapib was not time dependent, whereas the potency of dalcetrapib significantly increased with extended preincubation. Anacetrapib, torcetrapib, and dalcetrapib compete with one another for binding CETP; however anacetrapib binds reversibly and dalcetrapib covalently to CETP. In addition, dalcetrapib was found to covalently label both human and mouse plasma proteins. Each CETP inhibitor induced tight binding of CETP to HDL, indicating that these inhibitors promote the formation of a complex between CETP and HDL, resulting in inhibition of CETP activity.

We have synthesized a series of C7-piperidine- and 4-aminopiperidine-substituted naphthyridinones, quinolinones, and dihydroquinazolinones that are highly potent inhibitors of both p38MAP kinase activity and TNF-alpha release. The 4-aminopentamethylpiperidine naphthyridinone 5, which was designed to block metabolism at major 'hot spots', combined excellent inhibitory potency with good oral bioavailability in the rat.

Experiments were carried out to determine whether complexes between MHC class I molecules and synthetic peptides are representative of those formed under more physiologically relevant conditions, with peptides derived intracellularly from processed antigens. Lysis of cells sensitized with exogenously provided and endogenously generated peptide analogues of the optimal nonameric peptide 58–66 (GILGFVFTL; derived from the influenza virus matrix protein) was compared. Endogenous loading was accomplished by expressing minigene DNA coding for alanine-substituted analogues of peptide 58–66 in HLA-A2-positive cells. Susceptibility to lysis by HLA-A2-restricted, peptide-specific cytotoxic lymphocytes was compared with lysis of cells sensitized with the same synthetic peptides. Although results were quite comparable, differences were observed. The endogenously presented analogues 58–66L60A, G61A, T65A, and L66A were recognized more efficiently than the corresponding exogenously presented analogues. This difference in recognition was most striking for peptide 58–66G61A. These results indicate the need for caution in using synthetic peptides in defining peptide binding motifs. Additional experiments with endogenously expressed analogues of 58–66 with substitutions other than alanine were carried out to define the interaction between this peptide and HLA-A2. Results are compatible with the interpretation that residues 58, 59, and 60 interact with pockets A, B, and D, respectively, in the HLA-A2 binding groove and that these interactions contribute to peptide binding.

Background Current literature suggests that dipeptidyl peptidase IV (DPP-IV; CD26) plays an essential role in T-dependent immune responses, a role that could have important clinical consequences. To rigorously define the role of DPP-IV in the immune system, we evaluated genetic and pharmacological inhibition of the enzyme on T-dependent immune responses in vivo. Results The DPP-IV null animals mounted robust primary and secondary antibody responses to the T dependent antigens, 4-hydroxy-3-nitrophenylacetyl-ovalbumin (NP-Ova) and 4-hydroxy-3-nitrophenylacetyl-chicken gamma globulin (NP-CGG), which were comparable to wild type mice. Serum levels of antigen specific IgM, IgG1, IgG2a, IgG2b and IgG3 were similar between the two groups of animals. DPP-IV null animals mounted an efficient germinal center reaction by day 10 after antigen stimulation that was comparable to wild type mice. Moreover, the antibodies produced by DPP-IV null animals after repeated antigenic challenge were affinity matured. Similar observations were made using wild type animals treated with a highly selective DPP-IV inhibitor during the entire course of the experiments. T cell recall responses to ovalbumin and MOG peptide, evaluated by measuring proliferation and IL-2 release from cells isolated from draining lymph nodes, were equivalent in DPP-IV null and wild type animals. Furthermore, mice treated with DPP-IV inhibitor had intact T-cell recall responses to MOG peptide. In addition, female DPP-IV null and wild type mice treated with DPP-IV inhibitor exhibited normal and robust in vivo cytotoxic T cell responses after challenge with cells expressing the male H-Y minor histocompatibility antigen. Conclusion These data indicate Selective inhibition of DPP-IV does not impair T dependent immune responses to antigenic challenge.

The primary purpose of the paper is to develop an approach to portfolio analysis in the Concept Decision (CD) process, which is an initiative from the 2006 Quadrennial Defense Review to improve the early stages of the defense acquisition process. The paper guides, in a general way, future practitioners in undertaking CD Evaluations of Alternatives (EoAs). The basic structure of such analyses is to identify zero-net-cost changes to the appropriate portfolio that would result in improved capabilities to meet specified challenges. The approach to portfolio analysis presented in this paper is as applicable to the tasks of the Institutional Reform and Governance (IR&G) Capabilities Portfolio Managers (CPMs) as they are to the tasks of the CD Evaluation of Alternatives study directors.

Section 814(c) of the National Defense Authorization Act (NDAA) for Fiscal Year 2007 required a federally funded research and development center (FFRDC) to assess mechanisms that could ensure an independent evaluation of contractor performance supporting award fee determinations. Specifically, the FFRDC was to assess the advantages of (1) using separate award fee pools controlled by the independent fee determination board and (2) allowing contractor assessments across programs in contrast to their being made solely on the basis of the contractor's performance against the criteria set in the award fee plan. IDA performed the assessment with a study group composed of veteran senior defense acquisition officials. The study group developed a tailored alternative scenario it believed was feasible and satisfied the requirements in the NDAA. Compared to the present award fee process, the proposed change would offer little net benefit at great risk of diluting program management's influence over the contractor's behavior, which would erode rather than improve the effectiveness of the award fee process.

Our review focused on the processes and procedures for the long-term acquisition of military equipment and systems essential for properly equipping and supporting the future military force structure. In the phase 2 report the team proposes three major sets of initiatives and one minor initiative action by the USD(AT&L).

This report documents Phase I of a project undertaken by the Institute for Defense Analyses (IDA), in cooperation with The CNA Corporation (CNAC) (the Team). The task was twofold: (1) to review and assess the current status of the many acquisition initiatives that have been recommended and/or attempted in recent years, and (2) to identify and analyze a subset of initiatives that the team finds to have potential for near term management emphasis that could provide visible improvements to the much criticized Defense acquisition system. The first major section identifies those initiatives that are proceeding satisfactorily without high-level attention at this time, or have been overtaken by events or otherwise proven unworthy of further high level attention. Forty-one such initiatives were identified and categorized. They range from initiatives that have been quite successful to those that have proven to be unexpectedly difficult, but worth continuing In the former category are such initiatives as the system for tracking the past performance of contractors, the new system for tracking military customer wait time, and the increase in progress payments to contractors from 75% to 80%. In the unexpectedly difficult category are such initiatives as streamlining the export control process and attracting more nontraditional companies to bid on DoD work. The team's overall judgment is that none of the 41 items listed in Section II rise to the level of importance in terms of either policy implications or potential payoff to warrant specific near-term attention by the Defense Acquisition Executive (DAE). This observation is more important than any detailed assessment of the individual past initiatives.

FTY720 is an immunosuppressive agent that modulates lymphocyte trafficking. It is phosphorylated in vivo to FTY720-phosphate (FTY-P) and binds to a family of G protein-coupled receptors recognizing sphingosine 1-phosphate (S1P) as the natural ligand. It has previously been reported that FTY-P blocks egress of lymphocytes from the thymus and lymph nodes, resulting in peripheral blood lymphopenia. We now report that FTY-P also causes displacement of marginal zone (MZ) B cells to the splenic follicles, an effect that is similar to that observed after in vivo administration of lipopolysaccharide. This effect is specific to B cells in the MZ, as treatment with FTY-P does not cause redistribution of the resident macrophage population. A small but statistically significant decrease in the expression of β1 integrin on MZ B cells was observed with FTY-P treatment. The redistribution of MZ B cells from the MZ sinuses does not abolish the ability of these cells to respond to the T-independent antigen, trinitrophenol-Ficoll. It has been proposed that the displacement of MZ B cells to the follicles is an indication of cell activation. Consistent with this, FTY-P caused an increase in percentage of MZ B cells expressing activation markers CD9, CD1d, and CD24. These results suggest that S1P receptors on MZ B cells are responsible for their mobilization to follicles.

Imidazo[1,2-a]pyridyl N-arylpyridazinones were hybridized from the classic pyridinylimidazoles and the more recent dual hydrogen bond acceptors, resulting in a new structural class of selective p38 MAP kinase inhibitors.

Human leukocyte antigen (HLA)-DM is an unconventional major histocompatibility complex (MHC) class II heterodimer that is important for B-cell-mediated antigen processing and presentation to MHC class II-restricted T cells. HLA-DM is encoded by two genes, DMA and DMB, which map to the MHC class II region, and shares some homology with MHC class I and class II proteins. Here we define the biochemical role of HLA-DM. Recombinant soluble HLA-DM heterodimers have been purified from culture supernatants of insect cell transformants. At pH 5.0, they induce the dissociation of a subset of peptides bound to HLA-DR, including a nested set of class-II-associated invariant chain peptides (CLIP). This process liberates HLA-DR and leads to the enhanced binding of exogenous peptides.

The influenza A virus matrix derived peptide with amino acids 57–68 (Lys-Gly-Ileu-Leu-Gly-Phe-Val-Phe-Thr-Leu-Thr-Val) is recognized by influenza virus HLA-A2 restricted CTL. Because of the large number of hydrophobic residues this peptide is very insoluble. Substitution with a number of polar amino acids resulted in a soluble peptide (Lys-Lys-Ala-Leu-Gly-Phe-Val-Phe-Thr-Leu-Asp-Lys) that was very effective in sensitizing HLA-A2 positive target cells. Further substitution of threonine in position 65 with lysine resulted in a soluble antagonist peptide that inhibited sensitization. Both agonist and antagonist peptides retained 20% of their biological activity when tyrosine was added at the N terminus. Soluble radio-iodinated peptides can now be prepared that will be useful reagents to study the interaction of peptides and class I molecules.