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15601572 | Caspases: potential targets for regulating cell death. | While in multicellular organisms all cells inexorably die, there are several different ways provided for the realization of cell death. One of them, apoptosis, represents a universal energy-dependent and tightly regulated physiologic process of cell death in both normal and pathologic tissues. The execution of apoptosi... |
15465867 | Cholesterol sensitivity and lipid raft targeting of Kir2.1 channels. | This study investigates how changes in the level of cellular cholesterol affect inwardly rectifying K+ channels belonging to a family of strong rectifiers (Kir2). In an earlier study we showed that an increase in cellular cholesterol suppresses endogenous K+ current in vascular endothelial cells, presumably due to effe... |
15465864 | Kinetics of protein-DNA interaction: facilitated target location in sequence-dependent potential. | Recognition and binding of specific sites on DNA by proteins is central for many cellular functions such as transcription, replication, and recombination. In the process of recognition, a protein rapidly searches for its specific site on a long DNA molecule and then strongly binds this site. Here we aim to find a mecha... |
15465862 | A model membrane protein for binding volatile anesthetics. | Earlier work demonstrated that a water-soluble four-helix bundle protein designed with a cavity in its nonpolar core is capable of binding the volatile anesthetic halothane with near-physiological affinity (0.7 mM Kd). To create a more relevant, model membrane protein receptor for studying the physicochemical specifici... |
15465861 | Aggregation of normal and sickle hemoglobin in high concentration phosphate buffer. | Sickle cell disease is caused by a mutant form of hemoglobin, hemoglobin S, that polymerizes under hypoxic conditions. The extent and mechanism of polymerization are thus the subject of many studies of the pathophysiology of the disease and potential treatment strategies. To facilitate such studies, a model system usin... |
15465859 | Phase diagrams describing fibrillization by polyalanine peptides. | Amyloid fibrils are the structural components underlying the intra- and extracellular protein deposits that are associated with a variety of human diseases, including Alzheimer's, Parkinson's, and the prion diseases. In this work, we examine the thermodynamics of fibril formation using our newly-developed off-lattice i... |
15549598 | pH-dependent multiple morphologies of novel aggregates of carboxyl-terminated polymide in water. | Rigid low-molecular-weight polyimide with two carboxyl ends (CPI) formed pH-dependent multiple morphologies including dimpled-beads, porous aggregates and vesicles via self-assembly in aqueous media. This is a rapid and conventional approach to a series of pH-dependent morphologies of mono-component aggregates based on... |
15543978 | Novel urea-linked cinchona-calixarene hybrid-type receptors for efficient chromatographic enantiomer separation of carbamate-protected cyclic amino acids. | Two novel diastereomeric cinchona-calixarene hybrid-type receptors (SOs) were synthesized by inter-linking 9-amino(9-deoxy)-quinine (AQN)/9-amino(9-deoxy)-epiquinine (eAQN) and a calix[4]arene scaffold via an urea functional unit. Silica-supported chiral stationary phases (CSPs) derived from these SOs revealed, for N-p... |
15537080 | Liquid chromatography analysis of monosubstituted sulfobutyl ether-beta-cyclodextrin isomers on porous graphitic carbon. | The retention behaviour of the three positional isomers of monosubstituted sulfobutyl ether-beta-cyclodextrin was investigated on a porous graphitic carbon (PGC) column. The influence of the mobile phase composition (nature and concentration of organic and electronic modifiers) was studied as well as the effect of colu... |
15535558 | Visual observation of contact-induced intercrystalline migration of aromatic species adsorbed in zeolites by fluorescence microscopy. | Intercrystalline migration and a migration-assisted chemical reaction of adsorbed aromatic species between zeolite particles in physical contact were visualized by fluorescence microscopy coupled with a particle manipulation technique. The luminescence color characteristics of particular zeolite particles originating f... |
15532699 | On the dynamics of water molecules at the protein solute interfaces. | Proteins, with the large variety of chemical groups they present at their molecular surface, are a class of molecules which can be very informative on most of the possible solute-solvent interactions. Hen egg white lysozyme has been used as a probe to investigate the complex solvent dynamics occurring at the protein su... |
15532581 | Enantioselective determination of the novel antidepressant mirtazapine and its active demethylated metabolite in human plasma by means of capillary electrophoresis. | Mirtazapine is a recent noradrenergic and specific serotonergic antidepressant drug. A capillary electrophoretic method has been developed for the enantioseparation and analysis of mirtazapine and its main active metabolite, N-desmethylmirtazapine, in human plasma. For method optimisation several experimental parameter... |
15532579 | Improved separation of metallothionein isoforms by the presence of cyclodextrin in capillary zone electrophoresis. | Capillary zone electrophoresis (CZE) with cyclodextrin (CD) in the polyacrylamide-coated capillary was used to study metallothionein (MT) forms in the horse kidney preparation produced commercially by Sigma. It is known that CDs form complexes with hydrophobic amino acids. The results show that the presence of CD impro... |
15532578 | Preconditions for reasonable detection sensitivity and for zone symmetry in electrophoretic separations of cluster borane anions. | Single-cage boron cluster anions with at least 11 cluster atoms, free of bonded functional groups that strongly absorb UV light, and their cobalt complexes have been the investigated compounds. Their UV-absorption spectra have absolute maxima between 200 and 215 nm. Corresponding molar extinction coefficients that are ... |
15532560 | Use of the new, single-isomer, hexakis(2,3-diacetyl-6-O-sulfo)-alpha-cyclodextrin in acidic methanol background electrolytes for nonaqueous capillary electrophoretic enantiomer separations. | The new, single-isomer, sulfated alpha-cyclodextrin, the sodium salt of hexakis(2,3-diacetyl-6-O-sulfo)-alpha-cyclodextrin (HxDAS), was used for the first time in acidic methanol background electrolytes (BGEs) to separate the enantiomers of weak base analytes by nonaqueous capillary electrophoresis (NACE). The concentr... |
15527122 | Gradient elution of organic acids on a beta-cyclodextrin column in the polar organic mode and its application to drug discovery. | A high performance liquid chromatographic method was developed that separated organic acids using the polar organic mode. The separation was obtained using a beta-cyclodextrin stationary phase with a mobile phase that was composed of acetonitrile/methanol/triethylamine (TEA)/acetic acid. The compounds were eluted under... |
15527116 | Analytical method for the quantitation of sertraline hydrochloride stereoisomers by electrokinetic chromatography. | Sertraline is a basic compound and of pharmaceutical application for antidepressant treatment. The compound has two chiral centers. Separation of the three enantiomeric impurities from the parent compound is challenging. In this study, we successfully separated all four stereoisomers by electrokinetic chromatography us... |
15526165 | Biological functions of the ING family tumor suppressors. | Early studies of the inhibitor of growth 1 ( ING1) gene, the founding member of the ING tumor suppressor family, demonstrated that this gene plays an important role in apoptosis and cellular senescence. Four other related genes have since been identified and found to be involved in various biological activities, includ... |
15526161 | Targeted polymeric micelles for delivery of poorly soluble drugs. | Polymeric micelles (micelles formed by amphiphilic block copolymers) demonstrate a series of attractive properties as drug carriers, such as high stability both in vitro and in vivo and good biocompatibility, and can be successfully used for the solubilization of various poorly soluble pharmaceuticals. These micelles c... |
15526157 | Biomimetic actuators: where technology and cell biology merge. | The structural and functional analysis of biological macromolecules has reached a level of resolution that allows mechanistic interpretations of molecular action, giving rise to the view of enzymes as molecular machines. This machine analogy is not merely metaphorical, as bio-analogous molecular machines actually are b... |
15524190 | Cyclodextrin-aided determination of iodate and bromate in drinking water by microcolumn ion chromatography with precolumn enrichment. | A selective and simple method for the determination of iodate (IO3-) and bromate (BrO3-) by microcolumn ion chromatography (IC) is presented. In this study, IO3- and BrO3- were determined as IBr2- and tribromide (Br3-), respectively, via a postcolumn reaction with bromide (Br) under acidic conditions with the aid of al... |
15514063 | The gene Sex-lethal of the Sciaridae family (order Diptera, suborder Nematocera) and its phylogeny in dipteran insects. | This article reports the cloning and characterization of the gene homologous to Sex-lethal (Sxl) of Drosophila melanogaster from Sciara coprophila, Rhynchosciara americana, and Trichosia pubescens. This gene plays the key role in controlling sex determination and dosage compensation in D. melanogaster. The Sxl gene of ... |
15509748 | Calcium release from presynaptic ryanodine-sensitive stores is required for long-term depression at hippocampal CA3-CA3 pyramidal neuron synapses. | Although Ca2+ release from internal stores has been proposed to be important for the induction of long-term synaptic plasticity, the importance of Ca2+ stores localized in presynaptic terminals remains unclear. Here, we have selectively applied pharmacological antagonists to either the presynaptic or postsynaptic cell ... |
15490450 | Chemical analysis of raw, dry-roasted, and honey-roasted licorice by capillary electrophoresis. | In herbal medicine, licorice is usually processed using a roasting procedure which might modify the chemical compositions in licorice. To test this hypothesis, licorice root samples were roasted under various conditions (with or without honey) and subsequently extracted by refluxing with 95% ethanol. The analysis of ch... |
15472914 | Diphosphines with expandable bite angles: highly active ethylene dimerisation catalysts based on upper rim, distally diphosphinated calix[4]arenes. | The binding properties of two large diphosphines, cone-5,17-dibromo-11,23-bis(diphenylphosphino)-25,26,27,28-tetrapropoxycalix[4]arene (1) and cone-5,17-bis(diphenylphosphino)-25,26,27,28-tetrapropoxycalix[4]arene (2) toward Ni(II) centres have been investigated. Whatever the starting complex, NiBr2 or [NiCp]BF4, quant... |
15390140 | The structural influence in the stability of polymer-bound diazonium salts. | Various new diazonium ions on a polymeric support that have a variety of counterions and complexation with crown ethers have been prepared, and the thermal stability of these resins over a larger temperature interval has been investigated. Nonisothermal kinetics applied to DSC data have been used predicting the lifetim... |
15390077 | CO2 in supramolecular chemistry: preparation of switchable supramolecular polymers. | CO2 gas was used to construct novel types of supramolecular polymers. Self-assembling nanostructures 11 and 13 were prepared, which employ both hydrogen bonding and dynamic, thermally reversible carbamate bonds. As precursors, calixarene ureas 1 and 2 were synthesized, which strongly aggregate/dimerize (K(D)>/=10(6) M(... |
15378685 | Synthesis and self-assembly of a rigid exotopic bisphenanthroline macrocycle: surface patterning and a supramolecular nanobasket. | The synthesis and characterisation of a rigid nanoscale macrocycle with two exotopic phenanthroline binding sites is reported. Scanning tunnelling microscopy (STM) at the solid-liquid interface reveals the formation of highly ordered monolayers of macrocycles with dimensions that are in good agreement with the calculat... |
15378684 | Phase-transfer agents as catalysts for a nucleophilic substitution reaction in microemulsions. | The reaction between 4-tert-butylbenzyl bromide and potassium iodide was carried out in microemulsions based on different nonionic surfactants, and the reaction rates were compared with those obtained in two-phase systems with added phase-transfer agent, either a quaternary ammonium salt or a crown ether. The reactions... |
15372661 | The influence of constitutional isomerism and change on molecular recognition processes. | Three constitutionally isomeric bis(naphthylmethyl)ammonium ions, in which the two naphthyl groups are substituted 1) both at their 1-positions, 2) one at its 1-position and the other at its 2-position, and 3) both at their 2-positions, have been investigated separately in solution for their propensities to undergo spo... |
15497969 | Molecular recognition of carbohydrates with acyclic pyridine-based receptors. | The recognition capabilities of acyclic pyridine-based receptors toward monosaccharides were evaluated. Aminopyridine receptors based on the 2,4,6-trimethyl- or 2,4,6-triethylbenzene frame show high beta vs alpha binding selectivity in the recognition of glucopyranosides. Amidopyridine receptors, which are sterically l... |
15497965 | Synthesis and spectroscopy of a series of substituted N-confused tetraphenylporphyrins. | A series of N-confused tetraphenylporphyrins (H(2)NCTPPs) with substituents on either the para- or the 3,5-positions of the meso phenyl rings were prepared using Lindsey conditions. Both electron-withdrawing and electron-donating groups were chosen in order to probe the effects of peripheral substitution on the propert... |
15496076 | Effect of halogenation on edge-face aromatic interactions in a beta-hairpin peptide: enhanced affinity with iodo-substituents. | [reaction: see text] In a model beta-hairpin peptide, we have found that the favorable interaction of cross-strand aromatic rings can be enhanced by up to 1 kcal mol(-1) with halogen substituents. It appears that the polarizability of the halogen atoms accounts for the increase in stability and that there is a direct i... |
15496073 | End-capping of a pseudorotaxane via Diels-Alder reaction for the construction of C60-terminated [2]rotaxanes. | [reaction: see text] The Diels-Alder reaction of various dienophiles such as C(60) with a pseudorotaxane having a sultine moiety afforded corresponding [2]rotaxanes in moderate yields. The introduction of a porphyrin moiety on the wheel component considerably enhanced the efficiency of the end-capping reaction with C(6... |
15496325 | Combined effect of pH and polysorbates with cyclodextrins on solubilization of naringenin. | pH control and inclusion complex formation are commonly used as solubilization techniques in formulating ionizable drugs. Naringenin is a weakly acid compound with a low water solubility. The role of both ionized and unionized species of naringenin in solution by complexation with beta-cyclodextrin, 2-hydroxypropyl-bet... |
15493930 | Calix[4]phyrins. Effect of peripheral substituents on conformational mobility and structure within a series of related systems. | A new, stepwise synthesis of calix[4]phyrins is described. It relies on the condensation of a ketone with pyrrole to form a dipyrromethane containing a quaternary carbon center that is subsequently condensed with an aromatic aldehyde. This methodology, in contrast to the previous rational approach described by this gro... |
15493925 | The helical alanine controversy: an (Ala)6 insertion dramatically increases helicity. | Employing chemical shift melts and hydrogen/deuterium exchange NMR techniques, we have determined the stabilization of the Trp-cage miniprotein due to multiple alanine insertions within the N-terminal alpha-helix. Alanine is shown to be uniquely helix-stabilizing and this stabilization is reflected in the global fold s... |
15493907 | Supramolecular nanocarrier of siRNA from PEG-based block catiomer carrying diamine side chain with distinctive pKa directed to enhance intracellular gene silencing. | An siRNA nanocarrier formed through self-assembly of PEG-based block catiomer possessing two distinct amino groups with different pKa values in a side chain was developed. This design provided the carrier with a sufficient siRNA complexation and an assumed buffering capacity in the endosomes, allowing it to exhibit rem... |
15493897 | Synthetic multifunctional pores with external and internal active sites for ligand gating and noncompetitive blockage. | Design, synthesis, and multifunctionality of p-octiphenyl beta-barrel pores with external LRL triads and internal HH dyads are described. Molecular recognition of anionic fullerenes > calixarenes > pyrenes by guanidinium arrays at the outer pore surface is shown to result in pore opening, whereas alpha-helix recognitio... |
15493895 | Cyclodextrin-initiated polymerization of cyclic esters in bulk: formation of polyester-tethered cyclodextrins. | Cyclodextrins were found to initiate ring-opening polymerization of some cyclic esters selectively to give a polyester with a CD at the chain end. |
15493892 | Synthesis of a calix[4]arene derivative for isolation of a stable cation radical salt for use as a colorimetric sensor of nitric oxide. | We have designed and synthesized a modified calixarene derivative (1) that allows, for the first time, the isolation of a stable cation radical salt that binds a single molecule of nitric oxide deep within its cavity with remarkable efficiency (KNO >108 M-1), as demonstrated by isolation of a crystalline complex [1, NO... |
15493889 | On the nature of dendrimer cross-linking by ring-closing metathesis. | The ring-closing metathesis (RCM) mediated cross-linking of dendrimer 1 and it subunits was examined. Through the combined use of MALDI-MS-TOF, SEC, NMR, and X-ray crystallographic analysis it was shown that the cross-links are formed with the following order of preference: type d >/= type c > type b > type a. |
15493885 | Synthesis of [1]rotaxane via covalent bond formation and its unique fluorescent response by energy transfer in the presence of lithium ion. | Although there have been a lot of reports on the synthesis and properties of [n]rotaxanes (mainly n = 2), only a few reports on the synthesis of [1]rotaxane has been published by Vögtle's group and others (see ref 5). Generally speaking, [1]rotaxane might be expected to exhibit properties different from other rotaxanes... |
15493884 | Photochemical production of nitric oxide via two-photon excitation with NIR light. | Herein we demonstrate the successful photochemical generation of nitric oxide via two-photon excitation (TPE) from the supramolecular complex PPIX-RSE ({mu-S,mu-S'-protoporphyrin-IX-bis(2-thioethyl)diester]tetranitrosyl-diiron). The TPE fluorescence spectra indicate efficient energy transfer from the PPIX antennae to t... |
15493882 | Mechanism of the Stoddart-Heath bistable rotaxane molecular switch. | We use quantum mechanics to characterize the structure and current-voltage performance of the Stoddart-Heath rotaxane-based programmable electronic switch. We find that the current when the ring is on the DNP is 37-58 times the current when the ring is on the TTF, in agreement with experiment (ratio of 10-100). This es... |
15376299 | Using hydrogen bonds to direct the assembly of crowded aromatics. | This Minireview details the design, synthesis, and self-assembly of a new class of crowded aromatics that form columnar superstructures. The assembly of these subunits produces helical and polar stacks, whose assembly can be directed with electric fields. In concentrated solutions, these self-assembled helical rods exh... |
15491214 | Formation and photoluminescence of silver nanoparticles stabilized by a two-armed polymer with a crown ether core. | Silver nanoparticles were synthesized by the use of a two-armed polymer with a crown ether core [poly(styrene)]-dibenzo-18-crown-6-[poly(styrene)] based on the flexibility of the polymer chains and the complex effect of crown ether with Ag(+) and Ag. The size of silver nanoparticles could be tailored by controlling the... |
15491208 | Influence of surfactants and antibody immobilization strategy on reducing nonspecific protein interactions for molecular recognition force microscopy. | Specific and nonspecific interactions between antibody-modified probes and substrate-immobilized proteins were monitored by atomic force microscopy (AFM). Probes were modified with anti-ovalbumin IgG antibodies immobilized in either an oriented or a random manner. The oriented immobilization of whole IgG was accomplish... |
15491205 | Adsorption of charged macromolecules at a gold electrode. | Using an optical reflectometer with impinging-jet system, the adsorption from aqueous solution onto gold of three charged macromolecules has been studied: the strong linear-chain polyelectrolyte polyvinyl pyridine (PVP(+)), the fifth-generation poly(propylene imine) dendrimer DAB-64, which has a pH-dependent charge and... |
15491196 | A nanoscale view of supramolecular stereochemistry in self-assembled monolayers of enantiomers and racemates. | The effect that molecular chirality has on the formation of monolayer structures by pure enantiomers and their racemates at the liquid/solid interface has been investigated for two chiral compounds (1 and 2) which differ from each other by the presence or absence of an ester function in their respective molecular struc... |
15491183 | Colloid stability of lipid/polyelectrolyte decorated latex. | The colloid stability of supramolecular assemblies composed of the synthetic cationic lipid dioctadecyldimethylammonium bromide (DODAB) on carboxymethyl cellulose (CMC) supported on polystyrene amidine (PSA) microspheres was evaluated via turbidimetry kinetics, dynamic light scattering for particle sizing, zeta-potenti... |
15491125 | Understanding nucleic acids using synthetic chemistry. | This Account describes work done in these laboratories that has used synthetic, physical organic, and biological chemistry to understand the roles played by the nucleobases, sugars, and phosphates of DNA in the molecular recognition processes central to genetics. The number of nucleobases has been increased from 4 to 1... |
15488720 | Effect of binary and ternary polyvinylpyrrolidone and/or hydroxypropyl-beta-cyclodextrin complexes on the photochemical and photosensitizing properties of Naproxen. | The effect of the polyvinylpyrrolidone and/or hydroxypropyl-beta-cyclodextrin on the photo-lability of aqueous solutions of the anti-inflammatory drug Naproxen was studied. Kinetic studies revealed that the presence of all of these additives reduced drug photodegradation. In all cases, the presence of the different add... |
15489358 | Diagnosis and assessment of trachoma. | Trachoma is caused by Chlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in... |
15489355 | Antibody therapy in the management of shiga toxin-induced hemolytic uremic syndrome. | Hemolytic uremic syndrome (HUS) is a disease that can lead to acute renal failure and often to other serious sequelae, including death. The majority of cases are attributed to infections with Escherichia coli, serotype O157:H7 strains in particular, which cause bloody diarrhea and liberate one or two toxins known as Sh... |
15489348 | Treatment of infections caused by metronidazole-resistant Trichomonas vaginalis. | Infections with the sexually transmitted protozoan Trichomonas vaginalis are usually treated with metronidazole, a 5-nitroimidazole drug derived from the antibiotic azomycin. Metronidazole treatment is generally efficient in eliminating T. vaginalis infection and has a low risk of serious side effects. However, studies... |
15482639 | An ocular drug delivery system containing zinc diethyldithiocarbamate and HPbetaCD inclusion complex--corneal permeability, anti-cataract effects and mechanism studies. | Our purpose was to study the formulation and anti-cataract effects of aqueous eye drops containing a high concentration of zinc diethyldithiocarbamate (Zn-DDC). A possible mechanism of the anti-cataract effect of Zn-DDC was also studied. Zn-DDC and hydroxypropyl-beta-cyclodextrin (HPbetaCD) inclusion complex (Zn-DDC/HP... |
15481977 | Architecture of P2Y nucleotide receptors: structural comparison based on sequence analysis, mutagenesis, and homology modeling. | Human P2Y receptors encompass at least eight subtypes of Class A G protein-coupled receptors (GPCRs), responding to adenine and/or uracil nucleotides. Using a BLAST search against the Homo sapiens subset of the SWISS-PROT and TrEMBL databases, we identified 68 proteins showing high similarity to P2Y receptors. To addre... |
15482753 | Treatment with piroxicam before embryo transfer increases the pregnancy rate after in vitro fertilization and embryo transfer. | <h4>Objective</h4>To examine the effect of beta-cyclodextrin piroxicam treatment for priming of the uterus on the pregnancy outcome of IVF-embryo transfer (ET) programs.<h4>Design</h4>Prospective, randomized, double-blinded placebo-controlled clinical study.<h4>Setting</h4>Large urban medical center.<h4>Patient(s)</h4>... |
15472968 | Continuous on-line derivatization and selective separation of D-aspartic acid by a capillary electrophoresis system with a continuous sample introduction interface. | A rapid and selective method is described for the separation of D-aspartic acid (D-Asp) using a continuous on-line derivatization system coupled to capillary electrophoresis (CE). D-Asp was derivatized using o-phthaldialdehyde/N-acetyl-L-cysteine (OPA/NAC). By on-line derivatization, amino acid enantiomers were automat... |
15472952 | Modified micellar electrokinetic chromatography in the analysis of catechins and xanthines in chocolate. | Modified micellar electrokinetic chromatography (MEKC) analysis of monomeric flavanols (catechin and epicatechin) and methylxanthines (caffeine and theobromine) in chocolate and cocoa was performed by using sodium dodecyl sulfate (SDS) as a principal component of the running buffer. Because of the reported poor stabili... |
15472950 | Separation of positional isomers by cucurbit[7]uril-mediated capillary electrophoresis. | A novel macrocyclic molecule, cucurbit[7]uril (CB[7]) was for the first time employed as an additive in capillary electrophoresis (CE). In similarity to other macrocyclic molecules, such as crown ethers, cyclodextrins (CDs) and calixarenes, CB[7] can form inclusion complexes with a variety of guest molecules due to its... |
15483414 | In silico experiments of existing and hypothetical cytokine-directed clinical trials using agent-based modeling. | <h4>Objectives</h4>To introduce a form of mathematical modeling, agent-based modeling (ABM), and demonstrate its potential uses in the evaluation of the dynamics of the innate immune response (IIR) and the development of possible treatments for systemic inflammatory response syndrome (SIRS)/multiple organ failure (MOF)... |
15372694 | Towards targeted MRI: new MRI contrast agents for sialic acid detection. | The detection of sialic acid in living systems is of importance for the diagnosis of several types of malignancy. We have designed and synthesized two new lanthanide ion ligands (L1 and L2) that are capable of molecular recognition of sialic acid residues. The basic structure of these ligands consists of a DTPA-bisamid... |
15372668 | Polarity effects on the photophysics of dendrimers with an oligophenylenevinylene core and peripheral fullerene units. | Highly soluble dendritic branches with fullerene subunits at the periphery and a carboxylic acid function at the focal point have been prepared by a convergent approach. They have been attached to an oligophenylenevinylene (OPV) core bearing two alcohol functions to yield dendrimers with two, four or eight peripheral C... |
15372586 | The mechanism of formation of amide-based interlocked compounds: prediction of a new rotaxane-forming motif. | Molecular modeling of four different reagent systems shows that the (free) energies of supramolecular interactions in the gas phase and in solution can explain the different reaction products (i.e., various sized macrocycles, catenanes, and linear oligomers) that are formed in classic amide-catenane-forming reactions. ... |
15372580 | Complexing mechanism of the lanthanide cations Eu3+, Gd3+, and Tb3+ with 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (dota)-characterization of three successive complexing phases: study of the thermodynamic and structural properties of the complexes by potentiometry, luminescence spectroscopy, and E... | Complexation of the lanthanides Eu3+, Gd3+, and Tb3+ with 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (dota) has been studied in solution by using potentiometry, luminescence spectrometry, and EXAFS. Three series of successive complexes were characterized by at least two of these methods: the immedi... |
15468180 | Quantifying intermolecular interactions: guidelines for the molecular recognition toolbox. | Molecular recognition events in solution are affected by many different factors that have hampered the development of an understanding of intermolecular interactions at a quantitative level. Our tendency is to partition these effects into discrete phenomenological fields that are classified, named, and divorced: aromat... |
15479107 | Helical folding of alkanes in a self-assembled, cylindrical capsule. | The reversible encapsulation of a series of normal alkane guests in a cylindrical host was studied by NMR methods. For small hydrocarbons such as n-pentane or n-hexane, two guests enter the host, and they move freely within. With n-heptane no encapsulation takes place. For longer alkanes such as n-decane, a single gues... |
15479096 | Self-assembly of biocidal nanotubes from a single-chain diacetylene amine salt. | We describe the facile two-step synthesis of nanotubes that form pure, well-defined, nanostructured materials. We have synthesized a secondary amine HBr salt as the headgroup of a single-chain diacetylenic lipid. This molecule can form a number of different self-assembled nanostructures in aqueous or organic solvents. ... |
15479064 | A new route to supramolecular isomers via molecular templating: nanosized molecular polygons of copper(I) 2-methylimidazolates. | A new facile synthetic strategy successfully leads to the isolation of two polygons of high numbers of sides constructed by simple, bent imidazolate bridging ligands and two-coordinate CuI ions upon templating of circular organic molecules, which were characterized by crystallography. |
15479063 | A polyamidoamine dendrimer-capped mesoporous silica nanosphere-based gene transfection reagent. | We synthesized a MCM-41-type mesoporous silica nanosphere (MSN)-based gene transfection system, where second generation (G2) polyamidoamines (PAMAMs) were covalently attached to the surface of MSN. The G2-PAMAM-capped MSN material (G2-MSN) was used to complex with a plasmid DNA (pEGFP-C1) that encodes for an enhanced g... |
15479061 | Nanopore formation by self-assembly of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15. | The self-assembly characteristics of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15 have been studied in this work. An AFM study of the topology of polymer films deposited from acid and basic solutions on a hydrophobic silicon substrate has been carried out. Under acidic conditions, p... |
15479057 | Fluorescence emission from dendrimers and its pH dependence. | A strong fluorescence emission was observed from different kinds of dendrimers under acidic condition. There was a remarkable difference in fluorescence properties between second and fourth generation NH2-terminated poly(amido amine) dendrimers. It can be assumed that the backbone of the dendrimer played the key role i... |
15479047 | How fluorous is poly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxide-co-tetrafluoroethylene) (Teflon AF)? | We investigated poly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxide-co-tetrafluoroethylene (Teflon AF 2400, Tg = 240 degrees C), a stable and permeable fluorous polymer, as a transport/extraction medium for solutes for the first time. From the study of transport behavior of a series of solutes (in chloroform solutio... |
15479040 | Toward mimicking viral geometry with metal-organic systems. | Icosahedral and cuboctahedral arrangements of calixarenes, a nanometer-scale, spheroidal assembly of 12 calixarene molecules, can be manipulated in a highly controlled fashion. Previously, such assemblies were observed to favor placement of the calixarenes at the vertexes of an icosahedron. A supramolecular constraint ... |
15476363 | Chiral recognition and resolution of the enantiomers of supramolecular triangular hosts: synthesis, circular dichroism, NMR, and X-ray molecular structure of [Li subset(R,R,R)-[CpRh(5-chloro-2,3-dioxopyridine)]3][Delta-Trisphat]. | The racemic triangular supramolecular host [CpRh(5-chloro-2,3-dioxopyridine)](3) (1) was prepared in high yield. Treatment with LiCl followed by addition of silver salt AgOTf gave the triflate salt species [Li subset[CpRh(5-chloro-2,3-dioxopyridine)](3)][OTf] (2). Subsequent anion metathesis using the optically pure ch... |
15476358 | Impact of variations in design of flexible bitopic bis(pyrazolyl)methane ligands and counterions on the structures of silver(I) complexes: dominance of cyclic dimeric architecture. | The new ligands 1,1,4,4-tetra(1-pyrazolyl)butane [CH(pz)(2)(CH(2))(2)CH(pz)(2), L2] and 1,1,5,5-tetra(1-pyrazolyl)pentane [CH(pz)(2)(CH(2))(3)CH(pz)(2), L3] have been prepared to determine the structural changes in silver(I) complexes, if any, that accompany the lengthening of the spacer group between two linked bis(py... |
15476354 | Chiral molecular squares based on angular bipyridines: self-assembly, characterization, and photophysical properties. | Chiral molecular squares 1-12 based on [M(dppe)](2+) metallocorners (M = Pd or Pt, and dppe = bis(diphenylphosphino)ethane) and new angular bipyridine bridging ligands derived from the 1,1'-binaphthyl framework were readily assembled and characterized by a variety of techniques including infrared, UV-vis, circular dich... |
15476343 | Interweaving 3D network with double helical tubes filled by 1D coordination polymer chains. | The hydrothermal reaction of mellitic acid, 4,4'-bipydine, and Cu(CH(3)COO)(2).H(2)O gave rise to a novel 3D supramolecular architecture interpenetrated by three types of coordination polymer motifs. Two independent [[Cu(2)(mellitate)(4,4'-bpy)(H(2)O)(2)](2)(-)] 3D polymers incorporating helical substructures were inte... |
15476342 | Rational design and crystal structure determination of a 3-D metal-organic jungle-gym-like open framework. | A new three-dimensional (3-D) jungle-gym-like open metal-organic framework has been synthesized from a two-dimensional (2-D) layer compound using a heterogeneous pillar insertion reaction. Both the starting 2-D layer and the resulting 3-D open compounds have been characterized using X-ray crystallography. |
15473790 | Structural analysis of porphyrin molecular squares using molecular mechanics and density-functional methods. | "Molecular squares" formed from Re(CO)(3)Cl corners and porphyrin sides have potential applications as hosts for catalytic sites and as building blocks for membranes. In these materials, knowledge of the conformations of the squares is important. Molecular-mechanics (MM) and density-functional (DF) calculations have be... |
15474093 | Comparative ultrastructure of collagen fibrils in uterine leiomyomas and normal myometrium. | <h4>Objective</h4>To examine the ultrastructural characteristics of extracellular matrix and mature collagen fibrils in uterine leiomyomas and compare them with those in adjacent normal myometrium.<h4>Design</h4>Analysis of paired leiomyoma-myometrium in surgical specimens.<h4>Setting</h4>Research center and tertiary c... |
15474061 | NMR spectroscopy of inclusion complex of D-(-)-chloramphenicol with beta-cyclodextrin in aqueous solution. | (1)HNMR spectroscopic study in D(2)O of mixtures of D-(-)-chloramphenicol (guest), present in two tautomeric forms in solution, and beta-cyclodextrin (host) revealed the formation of 1:1 inclusion complex in which aromatic ring of the guest is tightly held by the host cavity. There seems no discrimination between the a... |
15474005 | The plasma membrane Ca2+ pump from proximal kidney tubules is exclusively localized and active in caveolae. | Plasma membrane Ca2+-ATPase is involved in the fine-tuned regulation of intracellular Ca2+. In this study, the presence of Ca2+-ATPase in caveolae from kidney basolateral membranes was investigated. With the use of a discontinuous sucrose gradient, we show that Ca2+-ATPase is exclusively located and fully active in cav... |
15471495 | Cross-linking dendrimers with allyl ether end-groups using the ring-closing metathesis reaction. | A third generation Frechet-type dendrimer containing 24 allyl ether end-groups was synthesized, cross-linked using the ring-closing metathesis (RCM) reaction, and the core was removed hydrolytically without significant fragmentation. The results are analogous to those previously reported for homoallyl ether dendrimers ... |
15469363 | Synthesis and metalation of novel fluorescent conjugated macrocycles. | [reaction: see text] Large shape-persistent conjugated macrocycles with tunable pore diameters in the nanometer regime were prepared by a simple, one-pot procedure. These new self-assembled macrocycles contain rings of 48-66 covalently bonded atoms and can bind multiple metal ions, forming soluble luminescent complexes... |
15469336 | Synthesis of cyclic hemiketals and spiroketals from dioxanorbornanes. | [reaction: see text] A new method for the synthesis of substituted pyranone hemiketals from dioxanorbornanes via SmI(2) is described. Also reported is a synthesis of spiro[4.5]ketals from analogous intermediates via acid-promoted deprotection/ketalization. |
15470146 | Distribution and injury-induced plasticity of cadherins in relationship to identified synaptic circuitry in adult rat spinal cord. | Cadherins are synaptically enriched cell adhesion and signaling molecules. In brain, they function in axon targeting and synaptic plasticity. In adult spinal cord, their localization, synaptic affiliation, and role in injury-related plasticity are mostly unexplored. Here, we demonstrate in adult rat dorsal horn that E-... |
15470143 | Molecular, topographic, and functional organization of the cerebellar cortex: a study with combined aldolase C and olivocerebellar labeling. | Aldolase C (zebrin) expression in Purkinje cells reveals stripe-shaped compartments in the cerebellar cortex. However, it is not clear how these compartments are related to cerebellar functional localization. Therefore, we identified olivocerebellar projections to aldolase C compartments by labeling climbing fibers wit... |
15469315 | Free energy, entropy, and induced fit in host-guest recognition: calculations with the second-generation mining minima algorithm. | This study applies a novel computational method to study molecular recognition for three sets of synthetic hosts: molecular clips, molecular tweezers, and a synthetic barbiturate receptor. The computed standard free energies of binding for the 12 binding reactions agree closely with experiment and provide insight into ... |
15469310 | Slow motion, trapping, and sorting of water- and chloroform-soluble porphyrins in nanowells. | A two-step self-assembly procedure on smooth, aminated silica particles established holey monolayers. At first, single, flat-lying porphyrin tetraamides (A) were bound covalently, followed by the build-up of a rigid monolayer made of diamido bolaamphiphiles (bolas) around the porphyrin islands. "Nanowells" around porph... |
15469292 | Synthesis and characterization of dendrimer templated supported bimetallic Pt-Au nanoparticles. | Bimetallic dendrimer-stabilized nanoparticles (DSNs) were used to prepare supported Pt-Au catalysts within the bulk miscibility gap for this binary system. Hydroxy-terminated generation 5 PAMAM dendrimers were used to prepare Cu(0) nanoparticles (NPs). The Cu(0) NPs were subsequently used to reduce K(2)PtCl(4) and HAuC... |
15469288 | Dendrimer interior functional group conversion and dendrimer metamorphosis--new approaches to the synthesis of oligo(dibenzyl sulfone) and oligo(phenylenevinylene) dendrimers. | A series of [G1] to [G3]-oligo(dibenzylsulfide) dendrimers containing up to 21 interior dibenzylsulfide moieties was prepared as starting materials toward the syntheses of two new series of oligo(dibenzyl sulfone) and oligo(phenylenevinylene) dendrimers using two different dendrimer-to-dendrimer conversion strategies. ... |
15469273 | Arylene ethynylene macrocycles prepared by precipitation-driven alkyne metathesis. | A convenient, multigram-scale synthesis of arylene ethynylene macrocycles near room temperature is described. Driven by the precipitation of a diarylacetylene byproduct, alkyne metathesis produces the desired macrocycles in one step from monomers in high yields. |
15469255 | Rendering poly(amidoamine) or poly(propylenimine) dendrimers temperature sensitive. | The poly(amidoamine) dendrimers having terminal isobutyramide (IBAM) groups were prepared by the reaction of isobutyric acid and the amine-terminated poly(amidoamine) dendrimers with generations (G) of 2 to 5 by using a condensing agent, 1,3-dicyclohexylcarbodiimide. 1H and 13C NMR revealed that an IBAM group was attac... |
15469237 | Stimuli-responsive supramolecular nanocapsules from amphiphilic calixarene assembly. | We synthesized tetrameric amphiphilic molecules based on a calixarene building block that self-assembles into a tunable and stable aggregation structure in aqueous solution. The amphiphilic calixarene molecules with a small hydrophilic part were observed to assemble into a vesicular structure that decreases significant... |
15255779 | Substrate specificity of Helicobacter pylori histone-like HU protein is determined by insufficient stabilization of DNA flexure points. | The histone-like HU protein is ubiquitous in the eubacteria. A role for Escherichia coli HU in compaction of the bacterial genome has been reported, along with regulatory roles in DNA replication, transposition, repair and transcription. We show here that HU from the human pathogen Helicobacter pylori, which has been i... |
15245330 | Comparative biochemical analysis of three bacterial prolyl endopeptidases: implications for coeliac sprue. | Prolyl endopeptidases have potential for treating coeliac sprue, a disease of the intestine caused by proteolytically resistant peptides from proline-rich prolamins of wheat, barley and rye. We compared the properties of three similar bacterial prolyl endopeptidases, including the known enzymes from Flavobacterium meni... |
15467253 | [A molecular basis for odorant recognition: olfactory receptor pharmacology]. | Olfactory receptors (ORs) comprise the largest super-family of rhodopsin-like G-protein coupled receptors (GPCR) that involve the recognition and discrimination of thousands of odorants. We recently succeeded in functional reconstitution of mouse ORs in mammalian cell lines and provided molecular evidence that structur... |
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