Mineralocorticoid receptor antagonist treatment of established pulmonary arterial hypertension improves interventricular dependence in the SU5416-hypoxia rat model.

Treatment with mineralocorticoid receptor (MR) antagonists beginning at the outset of disease, or early thereafter, prevents pulmonary vascular remodeling in preclinical models of pulmonary arterial hypertension (PAH). However, the efficacy of MR blockade in established disease, a more clinically relevant condition, remains unknown. Therefore, we investigated the effectiveness of two MR antagonists, eplerenone (EPL) and spironolactone (SPL), after the development of severe right ventricular (RV) dysfunction in the rat SU5416-hypoxia (SuHx) PAH model.

Role of bacterial motility in differential resistance mechanisms of silver nanoparticles and silver ions.

Unlike conventional antimicrobials, the study of bacterial resistance to silver nanoparticles (AgNPs) remains in its infancy and the mechanism(s) through which it evolves are limited and inconclusive. The central question remains whether bacterial resistance is driven by the AgNPs, released Ag(I) ions or a combination of these and other factors. Here, we show a specific resistance in an Escherichia coli K-12 MG1655 strain to subinhibitory concentrations of AgNPs, and not Ag(I) ions, as indicated by a statistically significant greater-than-twofold increase in the minimum inhibitory concentration occurring after eight repeated passages that was maintained after the AgNPs were removed and reintroduced.

Emerging investigator series: characterization of silver and silver nanoparticle interactions with zinc finger peptides.

In biological systems, chemical and physical transformations of engineered silver nanomaterials (AgENMs) are mediated, in part, by proteins and other biomolecules. Metalloprotein interactions with AgENMs are also central in understanding toxicity and antimicrobial and resistance mechanisms. Despite their readily available thiolate and amine ligands, zinc finger (ZF) peptides have thus far escaped study in reaction with AgENMs and their Ag(I) oxidative dissolution product.

Lysyl oxidase in cancer inhibition and metastasis.

Lysyl oxidase is an extracellular matrix, copper - dependent amine oxidase that catalyzes a key enzymatic step in the crosslinking of collagen and elastin. The enzyme is synthesized as a propeptide that is cleaved by procollagen - C - proteinase into two distinct parts: the mature form and the LOX propeptide. The mature enzyme plays a key role in modifying the extracellular matrix and as a result has been implicated in playing a role in the formation of cancer "niches" where tumors will develop and eventually metastasize.

Efficient Energy Transfer from Near-Infrared Emitting Gold Nanoparticles to Pendant Ytterbium(III).

Here, we demonstrate efficient energy transfer from near-infrared-emitting ortho-mercaptobenzoic acid-capped gold nanoparticles (AuNPs) to pendant ytterbium(III) cations. These functional materials combine the high molar absorptivity (1.21 × 10 M cm) and broad excitation features (throughout the UV and visible regions) of AuNPs with the narrow emissive properties of lanthanides.

Identification of Histidine 303 as the Catalytic Base of Lysyl Oxidase via Site-Directed Mutagenesis.

Lysyl oxidase (LOX) is a copper-dependent amine oxidase enzyme that catalyzes the formation of crosslinkages of collagen and elastin in connective tissues by oxidative deamination of lysine. Using site-directed mutagenesis, Histidine 303 has been shown to be a key residue that acts as the necessary catalytic base for this enzyme to function properly. Histidine 303 was mutated to isoleucine to remove catalytic activity and to aspartate and glutamate, respectively, in order to provide alternate residues that could act as a general base that could maintain catalytic activity.

Ligand density quantification on colloidal inorganic nanoparticles.

Colloidal inorganic nanoparticles are being used in an increasingly large number of applications ranging from biological imaging to television displays. In all cases, nanoparticle surface chemistry can significantly impact particle physical properties, processing, and performance. The first step in leveraging this tunability is to develop analytical approaches to describe surface chemical features.

Impact of As-Synthesized Ligands and Low-Oxygen Conditions on Silver Nanoparticle Surface Functionalization.

Here, we compare the ligand exchange behaviors of silver nanoparticles synthesized in the presence of two different surface capping agents: poly(vinylpyrrolidone) (MW = 10 or 40 kDa) or trisodium citrate, and under either ambient or low-oxygen conditions. In all cases, we find that the polymer capping agent exhibits features of a weakly bound ligand, producing better ligand exchange efficiencies with an incoming thiolated ligand compared to citrate. The polymer capping agent also generates nanoparticles that are more susceptible to reactions with oxygen during both synthesis and ligand exchange.

Overexpression of Soluble Recombinant Human Lysyl Oxidase by Using Solubility Tags: Effects on Activity and Solubility.

Lysyl oxidase is an important extracellular matrix enzyme that has not been fully characterized due to its low solubility. In order to circumvent the low solubility of this enzyme, three solubility tags (Nus-A, Thioredoxin (Trx), and Glutathione-S-Transferase (GST)) were engineered on the N-terminus of mature lysyl oxidase. Total enzyme yields were determined to be 1.

Description and Role of Bimetallic Prenucleation Species in the Formation of Small Nanoparticle Alloys.

We report the identification, description, and role of multinuclear metal-thiolate complexes in aqueous Au-Cu nanoparticle syntheses. The structure of these species was characterized by nuclear magnetic resonance spectroscopy, mass spectrometry, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy techniques. The observed structures were found to be in good agreement with thermodynamic growth trends predicted by first-principles calculations.

Ligand-Mediated "Turn On," High Quantum Yield Near-Infrared Emission in Small Gold Nanoparticles.

Small gold nanoparticles (∼1.4-2.2 nm core diameters) exist at an exciting interface between molecular and metallic electronic structures.

Quantitative analysis of thiolated ligand exchange on gold nanoparticles monitored by 1H NMR spectroscopy.

We use nuclear magnetic resonance spectroscopy methods to quantify the extent of ligand exchange between different types of thiolated molecules on the surface of gold nanoparticles. Specifically, we determine ligand density values for single-moiety ligand shells and then use these data to describe ligand exchange behavior with a second, thiolated molecule. Using these techniques, we identify trends in gold nanoparticle functionalization efficiency with respect to ligand type, concentration, and reaction time as well as distinguish between functionalization pathways where the new ligand may either replace the existing ligand shell (exchange) or add to it ("backfilling").