Search results for "choline"

Polymorphic domains in monolayers of isomeric triple-chain phospholipids

1991

Monolayers of two isomeric branched chain phosphatidyl cholines at the air/water interface have been studied by means of fluorescence microscopy. The lipids differ in the position of the branched chain at the glycerol backbone and carry three chains per headgroup of almost equal length. Most qualitative features of the compression isotherms are similar except a difference of 4 A2/molecule in the minimum molecular area at high lateral pressures. This indicates a more condensed solid phase of compound C2 and is also reflected in the shapes of domains observed in the LE/LC phase coexistence range: domains with sharp edges and a mostly hexagonal shape are formed. On the other hand, the compound…

in vitro biological evaluation of folate-functionalized block copolymer micelles for selective anti-cancer drug delivery.

2008

The main objective of this study was to evaluate the ability of folic acid-functionalized diblock copolymer micelles to improve the delivery and uptake of two poorly water-soluble anti-tumor drugs, tamoxifen and paclitaxel, to cancer cells through folate receptor targeting. The diblock copolymer used in this study comprised a hydrophilic poly[2-(methacryloyloxy)ethyl phosphorylcholine] (MPC) block, carrying at the chain end the folate targeting moiety, and a pH-sensitive hydrophobic poly[2-(diisopropylamino)ethyl methacrylate] (DPA) block (FA-MPC-DPA). The drug-loading capacities of tamoxifen- and paclitaxel-loaded micelles were determined by high performance liquid chromatography and the m…

Unusual triskelion patterns and dye-labelled GUVs: consequences of the interaction of cholesterol-containing linear-hyperbranched block copolymers wi…

2015

Cholesterol (Ch) linked to a linear-hyperbranched block copolymer composed of poly(ethylene glycol) (PEG) and poly(glycerol) (hbPG) was investigated for its membrane anchoring properties. Two polyether-based linear-hyperbranched block copolymers with and without a covalently attached rhodamine fluorescence label (Rho) were employed (Ch-PEG30-b-hbPG23 and Ch-PEG30-b-hbPG17-Rho). Compression isotherms of co-spread 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) with the respective polymers were measured on the Langmuir trough and the morphology development of the liquid-condensed (LC) domains was studied by epi-fluorescence microsc…

Coiled-Coil Lipopeptides Mimicking the Prehairpin Intermediate of Glycoprotein gp41

2009

Expression and renaturation of the N-terminal extracellular domain of torpedo nicotinic acetylcholine receptor alpha-subunit.

1998

The N-terminal extracellular region (amino acids 1-209) of the alpha-subunit of the nicotinic acetylcholine receptor (nAChR) from Torpedo marmorata electric tissue was expressed as inclusion bodies in Escherichia coli using the pET 3a vector. Employing a novel protocol of unfolding and refolding, in the absence of detergent, a water-soluble globular protein of 25 kDa was obtained displaying approximately 15% alpha-helical and 45% beta-structure. The fragment bound alpha-[3H]bungarotoxin in 1:1 stoichiometry with a KD value of 0.5 nM as determined from kinetic measurements (4 nM from equilibrium binding). The kinetics of association of toxin and fragment were of second order, with a similar …

The membrane environment modulates self-association of the human GpA TM domain--implications for membrane protein folding and transmembrane signaling.

2010

Abstract The influence of lipid bilayer properties on a defined and sequence-specific transmembrane helix–helix interaction is not well characterized yet. To study the potential impact of changing bilayer properties on a sequence-specific transmembrane helix–helix interaction, we have traced the association of fluorescent-labeled glycophorin A transmembrane peptides by fluorescence spectroscopy in model membranes with varying lipid compositions. The observed changes of the glycophorin A dimerization propensities in different lipid bilayers suggest that the lipid bilayer thickness severely influences the monomer–dimer equilibrium of this transmembrane domain, and dimerization was most effici…

Self-assembly mechanism of nanoparticles of Ni-based Prussian Blue analogues at the air/liquid interface: a synchrotron X-ray reflectivity study.

2015

Prussian Blue analogue (PBA) nanoparticles can be self-assembled at air/liquid interfaces to build novel materials with interesting magnetic features. Herein, we study the influence of the size of PBA Cs0.4 Ni[Cr(CN)6 ]0.9 and K0.25 Ni[Fe(CN)6 ]0.75 nanoparticles on the self-assembly behavior by synchrotron X-ray reflectivity. Both nanoparticles show similar Z-potential values. The phospholipid dipalmitoylphosphatidylcholine and the amino surfactant dimethyldioctadecylammonium have been used as Langmuir monolayers to anchor the PBA nanoparticles and study the interplay of forces directing the self-assembly of the nanoparticles at the surfactant/liquid interface. Whereas Cs0.4 Ni[Cr(CN)6 ]0.…

Pseudocholinesterase Activity in Organophosphate Poisoning after Storage of Unseparated Blood Samples at Room Temperature for 3 Weeks

2005

Suppressed pseudocholinesterase activity is a well-established laboratory finding in patients with serious organophosphate poisoning (1). Recently, a 48-year-old man with suspected ingestion of methyl parathion died, and the postmortem examination was not indicative. After 3 weeks, an overlooked specimen was discovered that had been collected from the patient ∼1 h after the suspected poisoning. The determination of pseudocholinesterase activity was requested. The blood sample, which showed complete hemolysis, was separated by centrifugation, and the pseudocholinesterase activity was determined. The result of 4.21 kU/L indicated the presence of only minor organophosphate poisoning without su…

Maximal degree of airway narrowing induced by methacholine and adenosine monophosphate: relationship with the decrease in forced vital capacity.

2010

Background Changes in forced vital capacity (FVC) may represent an indirect method for the detection of plateau in response to inhaled bronchoconstrictor agents. Objective To determine the relationship between the level of plateau obtained with either methacholine or adenosine monophosphate (AMP) and the decrease in FVC induced by each bronchoconstrictor agent. Methods Airway responsiveness to high concentrations of methacholine and AMP was determined in patients with intermittent asthma (n = 41) or allergic rhinitis (n = 26). Furthermore, allergen-induced changes in the response to each bronchoconstrictor agent were investigated in 18 pollen-sensitive patients. Concentration-response curve…

Effect of cigarette smoking on airway responsiveness to adenosine 5'-monophosphate in subjects with allergic rhinitis.

2003

Study objectives: The objective of this study was to determine differences in airway responsiveness to adenosine 5-monophosphate (AMP) between smokers and nonsmokers with allergic rhinitis. Methods: A total of 41 adults with allergic rhinitis (16 smokers and 25 nonsmokers) were challenged with increasing concentrations of methacholine and AMP. Airflow was assessed after each concentration, and the response to each bronchoconstrictor agent was measured by the provocative concentration required to produce a 20% fall in FEV1 (PC20). Results: The geometric mean PC20 AMP values were significantly lower in smokers than in nonsmokers: 72.4 mg/mL (95% confidence interval [CI], 33.9 to 154.9) vs 204…