Preparation and characterization of p-toluene sulfonyl ester and amino derivatives of tri- and poly(ethylene glycol)

Methods described in the literature are inadequate for the preparation of pure polyethylene glycol (PEG) tosylate. Therefore an improved method is presented. The hydroxyl groups on PEG can be quantitatively converted into the tosylate and isolated from the reaction medium free from impurities with no chain cleavage or reduction in molecular weight. 1,2-Di(N-phenyl 2-aminoethoxy) ethane, α,ω-di(N-phenyl 2-aminoethyl) poly(oxyethylene), and α,ω-di(N-phenyl, N-benzyl 2-aminoethyl) poly(oxyethylene) were prepared from the tosylates of tri- and poly(ethylene glycol)s and the corresponding primary and secondary aromatic amines.     

Immunoassay of P-glycoprotein on single cell by capillary electrophoresis with laser induced fluorescence detection

The cellular mechanism based on P-glycoprotein (PGP) for its drug pump function has become very important in multidrug resistance (MDR) research. A method has been established to characterize PGP on single K562 cell by coupling capillary electrophoresis with laser induced fluorescence detection. A permeable intact cell after the immunoassay binding with fluorescence labeling antibody was injected into the capillary and directly separated without lysis. It was found that once 5-10 optional cells were detected in batch, the PGP amount on this cell line could be outlined and calculated clearly. The PGP amount on K562 MDR cell line is 3.88 times higher than that on K562 sensitive cell line. These two cell lines with immunoassay binding were also analyzed by injection of multi-cells in order to improve the throughput. A resistance factor so called multidrug resistance multiple (MRM) was introduced to evaluate the MDR difference between cell lines. The MRM values of the cell line K562 measured by single cell analysis are well correlated with those by flow cytometry, which also prove the validity of our method in single cell analysis for the possibility of cancer diagnosis, pharmacokinetics and drug screening in future.     

Stereochemistry and dynamic behavior of some synthetic “angular” profisetinidin tetraflavanoid derivatives

The structure and stereochemistry of four synthetic “angular” tetraflavanoid-condensed tannin derivatives are examined by high-resolution variable temperature ¹H NMR. spectroscopy, and hence correlated with their dynamic behavior. Three “angular” oligomers exist as stable rotational isomers at ambient temperatures, thus contrasting with the mobility about their interflavanoid bonds of most natural profisetinidin “trimeric” and “tetrameric” homologs. A “linear” tetraflavanoid analog results from one of these regioselectively controlled condensations.     

Self-assembly via ionic interactions of calix[6]arene-based receptors displaying remarkable host-guest properties toward neutral guests

The association of a C_3v-symmetrical calix[6]tris-amine with different concave tris-carboxylic acids of various degrees of flexibility has been explored by ¹H NMR spectroscopy. In all cases, self-assembled structures directed by the selective inclusion of a neutral guest molecule were obtained, the more preorganized being stable in protic solvents. With a rigid C₃-symmetrical cap, chiral guest recognition in the calixarene cavity resulted. A large tris-acidic partner gave a unique molecular ditopic receptor that is able to simultaneously accommodate two neutral molecules in two distinct hydrophobic cavities with different binding processes.     

Perfluormethyl-Element-Liganden. XXIX. Darstellung und spektroskopische Untersuchungen von M(CO)4L2-Komplexen (M = Cr,Mo, W; L = Me2PSMe,Me2PSeMe, (CF3)2PSMe, (CF3)2PSeMe)

Perfluoromethyl Element Ligands. XXIX. Preparation and Spectroscopic Investigation of M(CO)₄L₂ Complexes (M ? Cr, Mo, W; L ? Me₂PSMe, Me₂PSeMe, (CF₃)₂PSMe, (CF₃)₂PSMe) The complexes M(CO)₄L₂ (see Inhaltsübersicht) have been prepared by the reaction of tetracarbonyl norbornadiene metal compounds M(CO)₄NBD with L at room temperature or 35°C, respectively. The cis-complexes formed in the first step undergo rearrangement to trans-isomers at higher temperatures. New compounds have been characterized by analytical and spectroscopic (IR, NMR, MS) methods.     

The chemistry of fluorine containing phosphaalkenes, arsaalkenes and selenocarbonyls

This review covers our extensive research activities in the area of fluorine containing phospha- and arsaalkenes as well as selenocarbonyls, which differ considerably in their properties and reactivities from their alkyl and aryl counterparts and thus contribute in a gratifying manner to the still growing field of unsaturated element-carbon compounds of 3rd and 4th row main group elements E. Of particular interest is the influence of the fluorine substituents and other small groups (OR, NR₂) with either inductive and/or mesomeric effects on the polarity and reactivity of the EC bond. Addition reactions of proton acidic and hydridic polar HX reactants as well as [2+2], [3+2] and [4+2] cycloadditions have been thoroughly studied. The results obtained allow a classification of the EC systems within five different types, A to E, and prove a change from “normal” to “inverse” heteroalkenes in this sequence. The ligand properties of some derivatives have also been investigated in some detail.     

Polymer-supported nitroxyl radical catalyst for selective aerobic oxidation of primary alcohols to aldehydes

PS-TEMPO, a polymer-supported 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), was successfully applied as a recyclable, active and selective catalyst for the oxidation of primary aliphatic and benzylic alcohols to aldehydes by molecular oxygen in the presence of Co(NO3)2 and Mn(NO3)2 as co-catalysts.     

The influence of different InsP(3) receptor isoforms on Ca(2+) signaling in tracheal smooth muscle cells

In airway myocytes, like in many cells, Ca(2+) signaling is controlled by inositol 1,4,5-trisphosphate (InsP(3)) via InsP(3) receptors (InsP(3)R) located in the sarco-endoplasmic reticulum. Three types of InsP(3)R exist, labeled Types 1, 2, and 3, which differ in their gating kinetics. We analyze a possible impact of the different gating kinetics of Type 1 and Type 3 InsP(3)R on the time course of cytosolic Ca(2+) concentration in tracheal smooth muscle cells upon agonist stimulation. Previous experimental data in rat tracheal myocytes showed that upon gradually increased stimulation with acetylcholine (ACh), a contractile agonist that acts via InsP(3) production, signal spikes, several spikes with declining maxima, and sustained oscillations appear. Our model reproduces the time courses of cytosolic Ca(2+) measured in tracheal myocytes. Moreover, by postulating slight variations in the model parameters which determine the total number of receptors expressed and the ratio between Type 1 and Type 3 InsP(3)R, it offers an explanation to the experimental observation of qualitatively different responses of cells within a presumably homogeneous tissue.