No abstract

The success of agents that inhibit tumor necrosis factor (TNF), such as infliximab, adalimumab and etanercept, has led to a desire for orally available small molecules that have a better safety profile and are less costly to produce than current agents. One target for anti-TNF therapy that is currently under investigation is TNF-converting enzyme, which promotes the release of soluble TNF from its membrane-bound precursor. Inhibitors of this enzyme with drug-like properties have been made and tested in the clinic. These inhibitors include TMI-005 and BMS-561392, both of which have entered into phase II clinical trials. This article summarizes preclinical and clinical findings regarding the use of inhibitors of TNF-converting enzyme for the treatment of rheumatoid arthritis.

The mechanism by which hypoxia [low partial pressure of O2 (pO2)] elicits signaling to regulate pulmonary arterial pressure is incompletely understood. We considered the possibility that, in addition to its effects on smooth muscle, hypoxia may influence pulmonary vascular tone through an effect on RBCs. We report that exposure of native RBCs to sustained hypoxia is accompanied by a buildup of heme iron-nitrosyl (FeNO) species that are deficient in pO 2-governed intramolecular transfer of NO to cysteine thiol, yielding a deficiency in the vasodilator S-nitrosohemoglobin (SNO-Hb). hemoglobin ͉ red blood cell vasodilation ͉ S-nitrosylation I n the systemic microcirculation, blood flow is regulated by physiological O 2 gradients that couple the O 2 content of blood to regulated vasodilation and vasoconstriction (1-3). Blood flow is thereby matched to tissue O 2 demand. An analogous mechanism operates in the lungs, where O 2 uptake (ventilation) is optimized through regulated vasodilation and vasoconstriction (perfusion). Blood flow is thereby matched to alveolar ventilation (2). Because it is Hb O 2 saturation, not the partial pressure of O 2 (pO 2 ), that is coupled to blood flow in vivo (1, 3) it has been deduced that RBCs may serve as O 2 sensors within the integrated vascular system. In support of this idea, it has been shown recently that RBCs can act as O 2 -responsive transducers of vasodilator and vasoconstrictor activity (4-10), at least partly by modulating the availability of [6][7][8]10,11). According to these studies, RBCs release NO bioactivity under hypoxia and sequester it at hyperoxia. The release of NO bioactivity would facilitate hypoxic vasodilation in peripheral tissues and oppose hypoxic pulmonary vasoconstriction (HPV) in the lungs. S-nitrosothiol (SNO)-deficientThe mechanism by which NO bioactivity escapes from RBCs is incompletely understood. It is generally accepted that the rapid reaction of NO with the hemes of Hb produces a heme-iron nitrosyl adduct (Hb [FeNO]) that exhibits no vasodilator activity (4,7,12). Hb also sustains S-nitrosylation at two cysteine residues conserved in all mammals and birds. Biochemical and mutational analyses (␤93Cys3Ala) indicate that S-nitrosohemoglobin (SNO-Hb) is formed upon oxygenation of Hb [FeNO] by means of heme-to-Cys NO transfer (13-15) and by transnitrosylative transfer from low-mass S-nitrosothiols (SNOs) (16,17). SNO-Hb is very stable in the oxygenated (or R) structure and thus cannot effectively dilate blood vessels (5, 10, 18). However, upon deoxygenation [or with change in the spin state of the hemes (3)], the vasodilator potency of SNO-Hb is markedly potentiated (5,16,18). Crystal structures and molecular models show that the ␤-Cys NO gains solvent access in the deoxygenated (or T) state (3, 19). Solvent-exposed NO can exchange with acceptor thiols within the N-terminal cytoplasmic domain of the RBC membrane anion exchange protein (AE1; band 3) (4, 15). Transnitrosylation of AE1 by SNO-Hb involves a direct protein-protein interaction. The st...

Redox regulation has been perceived as a simple on-off switch in proteins (corresponding to reduced and oxidized states). Using the transcription factor OxyR as a model, we have generated, in vitro, several stable, posttranslational modifications of the single regulatory thiol (SH), including S-NO, S-OH, and S-SG, and shown that each occurs in vivo. These modified forms of OxyR are transcriptionally active but differ in structure, cooperative properties, DNA binding affinity, and promoter activities. OxyR can thus process different redox-related signals into distinct transcriptional responses. More generally, our data suggest a code for redox control through which allosteric proteins can subserve either graded (cooperative) or maximal (noncooperative) responses, and through which differential responsivity to redox-related signals can be achieved.

We report the discovery of a novel, potent, and selective amidosulfonamide nonazapirone 5-HT1A agonist for the treatment of anxiety and depression, which is now in Phase III clinical trials for generalized anxiety disorder (GAD). The discovery of 20m (PRX-00023), N-{3-[4-(4-cyclohexylmethanesulfonylaminobutyl)piperazin-1-yl]phenyl}acetamide, and its backup compounds, followed a new paradigm, driving the entire discovery process with in silico methods and seamlessly integrating computational chemistry with medicinal chemistry, which led to a very rapid discovery timeline. The program reached clinical trials within less than 2 years from initiation, spending less than 6 months in lead optimization with only 31 compounds synthesized. In this paper we detail the entire discovery process, which started with modeling the 3D structure of 5-HT1A using the PREDICT methodology, and then performing in silico screening on that structure leading to the discovery of a 1 nM lead compound (8). The lead compound was optimized following a strategy devised based on in silico 3D models and realized through an in silico-driven optimization process, rapidly overcoming selectivity issues (affinity to 5-HT1A vs alpha1-adrenergic receptor) and potential cardiovascular issues (hERG binding), leading to a clinical compound. Finally we report key in vivo preclinical and Phase I clinical data for 20m tolerability, pharmacokinetics, and pharmacodynamics and show that these favorable results are a direct outcome of the properties that were ascribed to the compound during the rational structure-based discovery process. We believe that this is one of the first examples for a Phase III drug candidate that was discovered and optimized, from start to finish, using in silico model-based methods as the primary tool.

Biomimetic analogues 1 of the microbial siderophore (iron carrier) ferrichrome were labeled via piperazine with various fluorescent markers at a site not interfering with iron binding or receptor recognition (compounds 10-12). These iron carriers were built from a tetrahedral carbon symmetrically extended with three strands, each containing an amino acid (G = glycyl, A = alanyl, L = leucyl and P = phenylalanyl) and terminated by a hydroxamic acid, which together define an octahedral iron-binding domain. A fourth exogenous strand provided the site for connecting various fluorescent markers via a short bifunctional linker. Iron(III) titrations, along with fluorescence spectroscopy, generated quenching of fluorescence emission of some of the probes used. The quenching process fits the Perrin model which reinforces the intramolecular quenching process, postulated previously.1 All tested compounds, regardless of their probe size, polarity, or the linker binding them to the siderophore analogue, promote growth of Pseudomonas putida with the same efficacy as the nonlabeled analogues 1, with the added benefit of signaling microbial activity by fluorescence emission. All G derivatives of compounds 10-12 were found to parallel the behavior of natural ferrichrome, whereas A derivatives mediated only a modest iron(III) uptake by P. putida. Incubation of various Pseudomonas strains with iron(III)-loaded G derivatives resulted in the build-up of the labels' fluorescence in the culture medium to a much larger extent than from the corresponding A derivatives. The fluorescence buildup corresponds to iron utilization by the cells and the release of the fluorescent labeled desferrisiderophore from the cell to the media. The fact that the microbial activity of these compounds is not altered by attachment of various fluorescent markers via a bifunctional linker proposes their application as diagnostic tools for detecting and identifying pathogenic microorganisms.

A new class of polyanhydrides synthesized from nonlinear hydrophobic fatty acid esters, based on ricinoleic, maleic acid, and sebacic acid, possessed desired physico‐chemical and mechanical properties for use as drug carriers. The polymers were synthesized by melt condensation to yield film‐forming polymers with molecular weights exceeding 100,000. Their rate of elimination from rats in the course of about 2 months was faster than that found for similar polyanhydrides previously tested. In vitro studies showed that these polymers underwent rapid degradation in the first 10 days. The drug release followed first‐order kinetics, showing a rapid drug release rate in the first 10 days which correlated with the degradation of the polymers. The fatty acid ester monomers underwent in vitro enzymatic degradation to the natural starting acids. Tests in rats demonstrated their toxicological inertness and biodegradability. © 1995 John Wiley & Sons, Inc.

Aqueous solutions of the calcium and sodium salts of dipicolinic acid (DPA) were shown to have weak fluorescence when excited at wavelengths near 300 nm, but no fluorescence was observed from DPA alone. Upon UV irradiation at 254 nm the fluorescence of all three forms increases dramatically. The emission spectrum of calcium-DPA (CaDPA) has a maximum at 406 nm with full width at half-maximum of 70 nm. Changes in the absorption spectrum of the irradiated solution and the fact that the changes neither in absorption nor in fluorescence reverse after several days in the dark indicate that a photochemical reaction has taken place. The shapes of the emission spectra for all three DPA forms were very close to identical for excitation wavelengths in the range of 270 to 310 nm and for UV irradiation up to three hours, suggesting that one particular photoproduct dominates in producing the enhanced fluorescence.