Improvement of the antimicrobial potency, pharmacokinetic and pharmacodynamic properties of albicidin by incorporation of nitrogen atoms.

The worrisome development and spread of multidrug-resistant bacteria demands new antibacterial agents with strong bioactivities particularly against Gram-negative bacteria. Albicidins were recently structurally characterized as highly active antibacterial natural products from the bacterium . Albicidin, which effectively targets the bacterial DNA-gyrase, is a lipophilic hexapeptide mostly consisting of amino benzoic acid units and only one α-amino acid.

Detection of vascular cell adhesion molecule-1 expression with USPIO-enhanced molecular MRI in a mouse model of cerebral ischemia.

Vascular damage plays a critical role after stroke, leading notably to edema, hemorrhages and stroke recurrence. Tools to characterize the vascular lesion are thus a real medical need. In this context, the specific nanoparticular contrast agent P03011, an USPIO (ultrasmall superparamagnetic iron oxide) conjugated to a peptide that targets VCAM-1 (vascular cell adhesion molecule-1), was developed to detect this major component of the vascular inflammatory response.

Peptidomimetic antibiotics target outer-membrane biogenesis in Pseudomonas aeruginosa.

Antibiotics with new mechanisms of action are urgently required to combat the growing health threat posed by resistant pathogenic microorganisms. We synthesized a family of peptidomimetic antibiotics based on the antimicrobial peptide protegrin I. Several rounds of optimization gave a lead compound that was active in the nanomolar range against Gram-negative Pseudomonas spp.

Recent progress in the discovery of macrocyclic compounds as potential anti-infective therapeutics.

Novel therapeutic strategies are urgently needed for the treatment of serious diseases caused by viral, bacterial and parasitic infections, because currently used drugs are facing the problem of rapidly emerging resistance. There is also an urgent need for agents that act on novel pathogen-specific targets, in order to expand the repertoire of possible therapies. The high throughput screening of diverse small molecule compound libraries has provided only a limited number of new lead series, and the number of compounds acting on novel targets is even smaller.

The design, structures and therapeutic potential of protein epitope mimetics.

Using a biologically relevant peptide or protein structure as a starting point for lead identification represents one of the most powerful approaches in modern drug discovery. Here, we focus on the protein epitope mimetic (PEM) approach, where folded 3D structures of peptides and proteins are taken as starting points for the design of synthetic molecules that mimic key epitopes involved in protein-protein and protein-nucleic acid interactions. By transferring the epitope from a recombinant to a synthetic scaffold that can be produced by parallel combinatorial methods, it is possible to optimize target affinity and specificity as well as other drug-like ADMET properties.

Anti-HIV activity and resistance profile of the CXC chemokine receptor 4 antagonist POL3026.

We have studied the mechanism of action of Arg(*)-Arg-Nal(2)-Cys(1x)-Tyr-Gln-Lys-(d-Pro)-Pro-Tyr-Arg-Cit-Cys(1x)-Arg-Gly-(d-Pro)(*) (POL3026), a novel specific beta-hairpin mimetic CXC chemokine receptor (CXCR)4 antagonist. POL3026 specifically blocked the binding of anti-CXCR4 monoclonal antibody 12G5 and the intracellular Ca(2+) signal induced by CXC chemokine ligand 12. POL3026 consistently blocked the replication of human immunodeficiency virus (HIV), including a wide panel of X4 and dualtropic strains and subtypes in several culture models, with 50% effective concentrations (EC(50)) at the subnanomolar range, making POL3026 the most potent CXCR4 antagonist described to date.

Discovery of novel, highly potent and selective beta-hairpin mimetic CXCR4 inhibitors with excellent anti-HIV activity and pharmacokinetic profiles.

Novel highly potent CXCR4 inhibitors with good pharmacokinetic properties were designed and optimized starting from the naturally occurring beta-hairpin peptide polyphemusin II. The design involved incorporating important residues from polyphemusin II into a macrocyclic template-bound beta-hairpin mimetic. Using a parallel synthesis approach, the potency and ADME properties of the mimetics were optimized in iterative cycles, resulting in the CXCR4 inhibitors POL2438 and POL3026.

[Backward flow of blood in the extracorporal circuit pressure transducers of the generator-monitors of hemodialysis].

Transmission of hepatitis C virus between hemodialysis patients occurs mainly between the patients treated simultaneously in the same sector or in the same room. The other mode of viral transmission occurs between two patients treated successively with the same hemodialysis generator-monitor and sharing the same environment. One of the vectors of this last mode of transmission could be the contamination of the system of measurement of pressure of the extracorporal blood circuit.

Characterization of phosphopeptide motifs specific for the Src homology 2 domains of signal transducer and activator of transcription 1 (STAT1) and STAT3.

Signal transducers and activators of transcription (STAT) 1 and STAT3 are activated by overlapping but distinct sets of cytokines. STATs are recruited to the different cytokine receptors through their Src homology (SH) 2 domains that make highly specific interactions with phosphotyrosine-docking sites on the receptors. We used a degenerate phosphopeptide library synthesized on 35-microm TentaGel beads and fluorescence-activated bead sorting to determine the sequence specificity of the peptide-binding sites of the SH2 domains of STAT1 and STAT3.

Rapid identification of phosphopeptide ligands for SH2 domains. Screening of peptide libraries by fluorescence-activated bead sorting.

A method for the identification of high-affinity ligands to SH2 domains by fluorescence-activated bead sorting (FABS) was established. Recombinant SH2 domains, expressed as glutathione S-transferase (GST) fusion proteins, were incubated with a phosphotyrosine (Y*)-containing peptide library. 6.

Pentapeptide identified as a monoclonal antibody binding site in the serine-protease domain of t-PA.

The first defined sequential epitope of the tissue plasminogen activator (t-PA) was determined by a monoclonal antibody against a synthetic peptide segment corresponding to peptide sequence 341-354 of t-PA. This segment was selected by computer assisted epitope prediction. Balb/c mice were immunized with catalase-peptide and tripalmitoyl-S-glyceryl-cys-teinyl-seryl-peptide conjugates.

Fine specificity of the B-cell epitopes recognized in HIV-1 NEF by human sera.

We have previously used partially overlapping synthetic nonapeptides to characterize the human natural antibody response against HIV-1 negative regulatory factor (NEF), and identified nine 5 to 13 amino acid long regions that were recognized by sera of HIV-1-infected individuals. In this report we define the minimal size of these epitopes with the use of shorter, from 3 to 8 amino acid long partially overlapping peptides covering the complete sequence of the previously identified reacting regions and the N- and C-terminal flanking sequences. We also introduce a new method for the analysis of the reactivities obtained with peptides of different lengths.

Immunological variation and immunohistochemical localization of HIV-1 Nef demonstrated with monoclonal antibodies.

Objective: To study the immunological and immunohistochemical nature of HIV-1 Nef.

Design: Monoclonal anti-Nef antibodies were generated and used to identify antigenic epitopes in Nef, to study immunological cross-reactivity between Nef from different isolates and to reveal the subcellular localization of Nef.

Methods: Monoclonal antibodies against recombinant HIV-1 Nef protein (BRU isolate) were generated in BALB/c mice.

Characterization of human monoclonal antibodies directed against the pp65-kD matrix antigen of human cytomegalovirus.

Human monoclonal antibodies specific for human cytomegalovirus (CMV) antigens have been established using peripheral blood lymphocytes from a seropositive donor. Immortalization of antigen-specific B cells was achieved by Epstein-Barr virus transformation followed by somatic cell fusion of antigen-specific lymphoblastoid cells. Four clones producing high-affinity antibodies (0.

Synthetic peptide segments from the Escherichia coli porin OmpF constitute leukocyte activators.

After characterization of the porin OmpF and selection of molecular structures responsible for leukocyte activation by using computer-assisted epitope analysis, the analogs OmpF (153-174) (containing amino acids 153 to 174), OmpF (157-174), and OmpF (275-285) were synthesized and tested. Like the native protein, the segments were mitogenic for BALB/c splenocytes and induced B lymphocyte differentiation into antibody-producing plasma cells and tumor cytotoxicity of macrophages against the fibroblast cell line L929. We thus demonstrated that defined peptide segments are responsible for the leukocyte-activating properties of a major bacterial surface protein.

Antigenic epitopes of NEF proteins from different HIV-1 strains as recognized by sera from patients with manifest and latent HIV infection.

Human immunodeficiency virus (HIV) infection that generally causes a strong antibody response toward HIV may sometimes occur in a latent form, characterized by seronegativity in assays based on structural HIV proteins. Latently infected individuals, however, often have an antibody response against the nonstructural regulatory HIV-1 protein NEF, a factor implicated in down-regulation of viral expression. In order to define the specificity of NEF antibodies, we looked for antibody response against more than 600 overlapping nonapeptides representing the total NEF sequence of three different HIV-1 isolates BRU, SF2, and MAL.