Redox Imbalance and Oxidative DNA Damage During Isoniazid Treatment of HIV-Associated Tuberculosis: A Clinical and Translational Pharmacokinetic Study.

Background: The potential for hepatotoxicity during isoniazid-based tuberculosis (TB) treatment presents a major challenge for TB control programs worldwide. We sought to determine whether pharmacokinetic exposures of isoniazid and its metabolites were related to cellular oxidation/reduction status and downstream markers of oxidative DNA damage.

Methods: We performed intensive pharmacokinetic sampling among isoniazid-treated patients to determine the relative plasma exposures of isoniazid, acetylisoniazid, hydrazine, and acetylhydrazine.

Determination of Rifampin Concentrations by Urine Colorimetry and Mobile Phone Readout for Personalized Dosing in Tuberculosis Treatment.

Background: Individual pharmacokinetic variability is a driver of poor tuberculosis (TB) treatment outcomes. We developed a method for measurement of rifampin concentrations by urine colorimetry and a mobile phone photographic application to predict clinically important serum rifampin pharmacokinetic measurements in children treated for TB.

Methods: Among spiked urine samples, colorimetric assay performance was tested with conventional spectrophotometric and the mobile phone/light box methods under various environmental and biologic conditions.

Attainment of target rifampicin concentrations in cerebrospinal fluid during treatment of tuberculous meningitis.

Objective: There is considerable uncertainty regarding the optimal use of rifampicin for the treatment of tuberculous (TB) meningitis. A pharmacokinetic modeling and simulation study of rifampicin concentrations in cerebrospinal fluid (CSF) during TB meningitis treatment was performed in this study.

Methods: Parameters for rifampicin pharmacokinetics in CSF were estimated using individual-level rifampicin pharmacokinetic data, and the model was externally validated in three separate patient cohorts.

A Pilot Study of Immune Activation and Rifampin Absorption in HIV-Infected Patients without Tuberculosis Infection: A Short Report.

Background: Rifampin malabsorption is frequently observed in tuberculosis patients coinfected with human immunodeficiency virus (HIV) but cannot be predicted by patient factors such as CD4+ T cell count or HIV viral load.

Methods: We sought to describe the relationship between HIV-associated immune activation, measures of gut absorptive capacity and permeability, and rifampin pharmacokinetic parameters in a pilot study of 6 HIV-infected, tuberculosis-uninfected patients who were naïve to antiretroviral therapy.

Results: The median rifampin area under the concentration-versus-time curve during the 8-hour observation period was 42.

Urine colorimetry for therapeutic drug monitoring of pyrazinamide during tuberculosis treatment.

Objectives: Pyrazinamide is a key drug in the first-line treatment regimen for tuberculosis, with a potent sterilizing effect. Although low pyrazinamide peak serum concentrations (C) are associated with poor treatment outcomes, many resource-constrained settings do not have sufficient laboratory capacity to support therapeutic drug monitoring (TDM). The objective of this study was to determine whether a colorimetric test of urine can identify tuberculosis patients with adequate pyrazinamide exposures, as defined by serum C above a target threshold.

IgG Binding Characteristics of Rhesus Macaque FcγR.

Indian rhesus macaques (Macaca mulatta) are routinely used in preclinical studies to evaluate therapeutic Abs and candidate vaccines. The efficacy of these interventions in many cases is known to rely heavily on the ability of Abs to interact with a set of Ab FcγR expressed on innate immune cells. Yet, despite their presumed functional importance, M.

Urine colorimetry to detect Low rifampin exposure during tuberculosis therapy: a proof-of-concept study.

Background: The cost and complexity of current approaches to therapeutic drug monitoring during tuberculosis (TB) therapy limits widespread use in areas of greatest need. We sought to determine whether urine colorimetry could have a novel application as a form of therapeutic drug monitoring during anti-TB therapy.

Methods: Among healthy volunteers, we evaluated 3 dose sizes of rifampin (150 mg, 300 mg, and 600 mg), performed intensive pharmacokinetic sampling, and collected a timed urine void at 4 h post-dosing.

Abasic phosphorothioate oligomers inhibit HIV-1 reverse transcription and block virus transmission across polarized ectocervical organ cultures.

In the absence of universally available antiretroviral (ARV) drugs or a vaccine against HIV-1, microbicides may offer the most immediate hope for controlling the AIDS pandemic. The most advanced and clinically effective microbicides are based on ARV agents that interfere with the earliest stages of HIV-1 replication. Our objective was to identify and characterize novel ARV-like inhibitors, as well as demonstrate their efficacy at blocking HIV-1 transmission.

An optimized, synthetic DNA vaccine encoding the toxin A and toxin B receptor binding domains of Clostridium difficile induces protective antibody responses in vivo.

Clostridium difficile-associated disease (CDAD) constitutes a large majority of nosocomial diarrhea cases in industrialized nations and is mediated by the effects of two secreted toxins, toxin A (TcdA) and toxin B (TcdB). Patients who develop strong antitoxin antibody responses can clear C. difficile infection and remain disease free.

Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach.

Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a D-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein-peptide-antibiotic complex.

Identification of a small-molecule inhibitor of HIV-1 assembly that targets the phosphatidylinositol (4,5)-bisphosphate binding site of the HIV-1 matrix protein.

The development of drug resistance remains a critical problem for current HIV-1 antiviral therapies, creating a need for new inhibitors of HIV-1 replication. We previously reported on a novel anti-HIV-1 compound, N(2)-(phenoxyacetyl)-N-[4-(1-piperidinylcarbonyl)benzyl]glycinamide (14), that binds to the highly conserved phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P(2)) binding pocket of the HIV-1 matrix (MA) protein. In this study, we re-evaluate the hits from the virtual screen used to identify compound 14 and test them directly in an HIV-1 replication assay using primary human peripheral blood mononuclear cells.

Discovery of a small-molecule antiviral targeting the HIV-1 matrix protein.

Due to the emergence of drug-resistant strains and the cumulative toxicities associated with current therapies, demand remains for new inhibitors of HIV-1 replication. The HIV-1 matrix (MA) protein is an essential viral component with established roles in the assembly of the virus. Using virtual and surface plasmon resonance (SPR)-based screening, we describe the identification of the first small molecule to bind to the HIV-1 MA protein and to possess broad range anti-HIV properties.

HIV-1 Env gp120 structural determinants for peptide triazole dual receptor site antagonism.

Despite advances in HIV therapy, viral resistance and side-effects with current drug regimens require targeting new components of the virus. Dual antagonist peptide triazoles (PT) are a novel class of HIV-1 inhibitors that specifically target the gp120 component of the viral spike and inhibit its interaction with both of its cell surface protein ligands, namely the initial receptor CD4 and the co-receptor (CCR5/CXCR4), thus preventing viral entry. Following an initial survey of 19 gp120 alanine mutants by ELISA, we screened 11 mutants for their importance in binding to, and inhibition by the PT KR21 using surface plasmon resonance.

Inhibiting early-stage events in HIV-1 replication by small-molecule targeting of the HIV-1 capsid.

The HIV-1 capsid (CA) protein plays essential roles in both early and late stages of virl replication and has emerged as a novel drug target. We report hybrid structure-based virtual screening to identify small molecules with the potential to interact with the N-terminal domain (NTD) of HIV-1 CA and disrupt early, preintegration steps of the HIV-1 replication cycle. The small molecule 4,4'-[dibenzo[b,d]furan-2,8-diylbis(5-phenyl-1H-imidazole-4,2-diyl)]dibenzoic acid (CK026), which had anti-HIV-1 activity in single- and multiple-round infections but failed to inhibit viral replication in peripheral blood mononuclear cells (PBMCs), was identified.

Inhibition of homologous recombination in human cells by targeting RAD51 recombinase.

The homologous recombination (HR) pathway plays a crucial role in the repair of DNA double-strand breaks (DSBs) and interstrand cross-links (ICLs). RAD51, a key protein of HR, possesses a unique activity: DNA strand exchange between homologous DNA sequences. Recently, using a high-throughput screening (HTS), we identified compound 1 (B02), which specifically inhibits the DNA strand exchange activity of human RAD51.

A carrier protein strategy yields the structure of dalbavancin.

Many large natural product antibiotics act by specifically binding and sequestering target molecules found on bacterial cells. We have developed a new strategy to expedite the structural analysis of such antibiotic-target complexes, in which we covalently link the target molecules to carrier proteins, and then crystallize the entire carrier-target-antibiotic complex. Using native chemical ligation, we have linked the Lys-D-Ala-D-Ala binding epitope for glycopeptide antibiotics to three different carrier proteins.

Monoclonal antibody m18 paratope leading to dual receptor antagonism of HIV-1 gp120.

We sought to identify sequences in the monoclonal antibody m18 complementarity determining regions (CDRs) that are responsible for its interaction with HIV-1 gp120 and inhibition of the envelope receptor binding sites. In the accompanying paper (DOI 10.1021/bi101160r), we reported that m18 inhibits CD4 binding through a nonactivating mechanism that, at the same time, induces conformational effects leading to inhibition of the coreceptor site.

Conformational and structural features of HIV-1 gp120 underlying the dual receptor antagonism by cross-reactive neutralizing antibody m18.

We investigated the interaction between cross-reactive HIV-1 neutralizing human monoclonal antibody m18 and HIV-1YU-2 gp120 in an effort to understand how this antibody inhibits the entry of virus into cells. m18 binds to gp120 with high affinity (KD≈5 nM) as measured by surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). SPR analysis further showed that m18 inhibits interactions of gp120 with both soluble CD4 and CD4-induced antibodies that have epitopes overlapping the coreceptor binding site.

The active core in a triazole peptide dual-site antagonist of HIV-1 gp120.

In an effort to identify broadly active inhibitors of HIV-1 entry into host cells, we previously reported a family of dodecamer triazole-peptide conjugates with nanomolar affinity for the viral surface protein gp120. This peptide class exhibits potent antiviral activity and the capacity to simultaneously inhibit interaction of the viral envelope protein with both CD4 and co-receptor. In this investigation, we minimized the structural complexity of the lead triazole inhibitor HNG-156 (peptide 1) to explore the limits of the pharmacophore that enables dual antagonism and to improve opportunities for peptidomimetic design.

Introducing metallocene into a triazole peptide conjugate reduces its off-rate and enhances its affinity and antiviral potency for HIV-1 gp120.

In this work, we identified a high affinity and potency metallocene-containing triazole peptide conjugate that suppresses the interactions of HIV-1 envelope gp120 at both its CD4 and co-receptor binding sites. The ferrocene-peptide conjugate, HNG-156, was formed by an on-resin copper-catalysed [2+3] cycloaddition reaction. Surface plasmon resonance interaction analysis revealed that, compared to a previously reported phenyl-containing triazole conjugate HNG-105 (105), peptide 156 had a higher direct binding affinity for several subtypes of HIV-1 gp120 due mainly to the decreased dissociation rate of the conjugate-gp120 complex.

Structural determinants for affinity enhancement of a dual antagonist peptide entry inhibitor of human immunodeficiency virus type-1.

Structure-activity correlations were investigated for substituted peptide conjugates that function as dual receptor site antagonists of HIV-1 gp120. A series of peptide conjugates were constructed via click reaction of both aryl and alkyl acetylenes with an internally incorporated azidoproline 6 derived from the parent peptide 1 (12p1, RINNIPWSEAMM). Compared to 1, many of these conjugates were found to exhibit several orders of magnitude increase in both affinity for HIV-1 gp120 and inhibition potencies at both the CD4 and coreceptor binding sites of gp120.

Wistar Kyoto and Wistar rats differ in the affective and locomotor effects of nicotine.

Anhedonia is a characteristic of clinical depression and has been associated with dysfunction of the mesolimbic dopaminergic system, a system also involved in mediating nicotine reward. To further examine the relationship between anhedonia, clinical depression and nicotine reward, the present experiment determined if Wistar Kyoto (WKY) rats, an animal model of clinical depression, differed from Wistar rats in nicotine conditioned place preference (CPP). Strain differences in nicotine-induced changes in locomotor activity also were determined simultaneously.