Trimethylammonium methyl esters (DMS) of polyene macrolides are products of the methylation of native polyene antibiotics with dimethyl sulfate. We isolated individual components of the DMS-aureofacin complex and characterized their toxicity and activity to induce permeability changes in cell membranes. The DMS-aureofacin complex contained five components readily separated by thin-layer chroma...

Slowly diffusing water molecules were found by quasi-elastic neutron scattering (QENS) in a sodium dodecyl sulfate (SDS) micellar solution, and both their diffusion coefficient (4.33 x 10(-6) cm2 x s(-1)) and mole fraction (0.057) were determined. After successfully checking the mean slowing down of solvent molecules by the gradient compensated stimulated spin-echo (GCSTE) pulse sequence NMR me...

We report a dramatic increase in foam stability for catanionic mixtures (myristic acid and cetyl trimethylammonium bromide, CTABr) with respect to that of CTABr solutions. This increase was related to the low surface tension, high surface concentration, and high viscoelastic compression moduli, as measured with rising bubble experiments and ellipsometry. Dialysis of the catanionic mixtures has ...

Bioremediation efforts sometimes rely on surfactants to enhance hydrocarbon bioavailability. However, synthetic surfactants are toxic to some degrading microorganisms. In this study we screened a natural surfactant-rich compartment, the sea surface microlayer (SML), for surfactant-resistant bacteria, using enrichment cultures of sodium dodecyl sulfate (SDS) and cetyl trimethylammonium bromide (...

The membrane-bound, 26 000-Mr penicillin-binding protein of Streptomyces K15 has been isolated in the form of an effective, penicillin-sensitive D-alanyl-D-alanine-cleaving peptidase exhibiting high transpeptidase activity (greater than 95%) and very low carboxy-peptidase activity (less than 5%). The penicillin-binding protein/transpeptidase can be extracted directly from the mycelium with N-ce...

Hepatocellular carcinoma (HCC) is one of the most frequent primary malignancies of the liver and is resistant to anticancer drugs. Hypoxia is a master cause of tumor resistance to chemotherapy. Hypoxia-inducible factor-one alpha (HIF-1α) plays a key role in the adaptive responses to hypoxic environments. HIF-1α is constitutively up-regulated in several tumor types might thus be implicated in tu...

Sorbent materials were developed utilizing two morphological structures, comprising either hexagonally packed pores (HX) or a disordered pore arrangement (CF). The sorbents were functionalized with combinations of two types of alkylammonium groups. When capture of perchlorate by the sorbents was compared, widely varying performance was noted as a result of differing morphology and/or functional...

We report the rational design of a chitosan-based drug delivery system. The chitosan derivative N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan chloride (HTCC) was ionically cross-linked by sodium tripolyphosphate (TPP) to form sub-200-nm microgels that are responsive to pH changes. When these microgels were loaded with methotrexate disodium (MTX), a cytotoxic drug for cancer treatment, and c...

Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine followed by glycidyl trimethylammonium chlorid to produce chitosan bearing amine (R1) and chitosan bearing both amine and quaternary ammonium chloride moieties (R2), respectively. The quaternary amine resin (R2) showed a higher ...