(+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl-N- hydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (CMI-392), a potent dual 5-lipoxygenase inhibitor and platelet-activating factor receptor antagonist.

By incorporating an N-hydroxyurea functionality onto diaryltetrahydrofurans, a novel series of compounds was investigated as dual 5-lipoxygenese (5-LO) inhibitor and platelet-activating factor (PAF) receptor antagonist. These dual functional compounds were evaluated in vitro for 5-LO inhibition in RBL cell extracts and human whole blood, and PAF receptor antagonism in a receptor binding assay. PAF-induced hemoconcentration and arachidonic acid- and TPA-induced ear edema in mice were used to determine in vivo activities. The structure-activity relationship analysis to define a preclinical lead is presented. (+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl- N-h ydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (40, CMI-392) was selected for further study. In the arachidonic acid-induced mouse ear edema model, 40 was more potent than either zileuton (a 5-LO inhibitor) or BN 50739 (a PAF receptor antagonist), and it demonstrated the same inhibitory effect as a physical combination of the latter two agents. These results suggest that a single compound which both inhibits leukotriene synthesis and blocks PAF receptor binding may provide therapeutic advantages over single-acting agents. The clinical development of compound 40 is in progress.

Relationship of inappropriate drug prescribing to increased length of hospital stay.

The relationship of inappropriate drug prescribing to increased length of hospital stay was studied. The medical records of 77 cases of pyelonephritis were reviewed retrospectively. Appropriateness of antimicrobial drug therapy was judged by three types of explicit screening criteria: drug-specific, patient-specific, and match of drug to infecting organism. Patients whose therapy passed all the criteria were hospitalized, on the average, two days less than those whose therapy failed one or more of the criteria. This was a significant difference (p less than 0.05). Age, seriousness of the pyelonephritis, or method of payment appeared to have no significant moderating effect on this result. However, the increased length of stay may not have been associated with only inappropriate prescribing, because the inappropriately prescribing physicians kept their patients hospitalized longer beyond the point of symptom remission than did the appropriately prescribing physicians. The study suggest that successful interventions for improving drug therapy could result in large cost savings.

A ligand-reversible dimerization system for controlling protein-protein interactions.

Chemically induced dimerization provides a general way to gain control over intracellular processes. Typically, FK506-binding protein (FKBP) domains are fused to a signaling domain of interest, allowing crosslinking to be initiated by addition of a bivalent FKBP ligand. In the course of protein engineering studies on human FKBP, we discovered that a single point mutation in the ligand-binding site (Phe-36 --> Met) converts the normally monomeric protein into a ligand-reversible dimer. Two-hybrid, gel filtration, analytical ultracentrifugation, and x-ray crystallographic studies show that the mutant (F(M)) forms discrete homodimers with micromolar affinity that can be completely dissociated within minutes by addition of monomeric synthetic ligands. These unexpected properties form the basis for a "reverse dimerization" regulatory system involving F(M) fusion proteins, in which association is the ground state and addition of ligand abolishes interactions. We have used this strategy to rapidly and reversibly aggregate fusion proteins in different cellular compartments, and to provide an off switch for transcription. Reiterated F(M) domains should be generally useful as conditional aggregation domains (CADs) to control intracellular events where rapid, reversible dissolution of interactions is required. Our results also suggest that dimerization is a latent property of the FKBP fold: the crystal structure reveals a remarkably complementary interaction between the monomer binding sites, with only subtle changes in side-chain disposition accounting for the dramatic change in quaternary structure.

Synthesis and activity of bivalent FKBP12 ligands for the regulated dimerization of proteins.

The total synthesis and in vitro activities of a series of chemical inducers of dimerization (CIDs) is described. The use of small-molecule CIDs to control the dimerization of engineered FKBP12-containing fusion proteins has been demonstrated to have broad utility in biological research as well as potential medical applications in gene and cell therapies. The facility and flexibility of preparation make this new class of wholly synthetic compounds exceptionally versatile tools for the study of intracellular signaling events mediated by protein-protein interactions or protein localization. While some congeners possess potency comparable to or better than the first generation natural product-derived CID, FK1012, structure-activity relationships are complex and underscore the need for application-specific compound optimizations.