Determination of mitoxantrone with a fiber-optic device

A major problem in therapeutic use of the cytostatic agent mitoxantrone is the occurrence of side effects. Estimation of the drug concentration in or next to the tumor can lead to a reduction of the toxicity through accurate dose adjustment. In this paper a method for the determination of mitoxantrone by a fibre-optic device is described. The advantage of the system is the possibility of remote sensing at the working site of the cytostatic agent by a method that is simple in handling and sufficient in sensitivity. The measuring principle is based on the blue colour of mitoxantrone. The function of the device was tested byin vitro assays; linear calibration curves in a concentration range between 2 and 10g of mitoxantrone per ml of sample solution were obtained.     

Chiral Diselenides from Benzylamines: Catalysts in the Diethylzinc Addition to Aldehydes

A series of new chiral diselenides with a N-atom in the side chain was prepared by a short synthetic sequence (Scheme 1). Only 1 mol-% of these diselenides catalyzed very effectively the diethylzinc addition to various aromatic and α,β-unsaturated aldehydes yielding the secondary alcohols in up to 98% ee (Scheme 2 and Tables 1 and 2). An asymmetric amplification was observed with these catalysts. Detailed NMR studies were performed to characterize the catalytically active species.     

Identification of gel-separated tumor marker proteins by mass spectrometry

Two-dimensional gel electrophoresis with subsequent analysis by mass spectrometry was applied to study differences in protein expression between benign and malignant solid tumors from human beast, lung and ovary cells. Cells from freshly resected clinical material were lysed and the extracts were subjected to isoelectric focusing with immobilized pH gradients followed by second-dimensional separation on 10-13% sodium dodecyl sulfate (SDS)/polyacrylamide gels. Polypeptides were identified using matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry after in-gel protein digestion. Some of the upregulated polypeptides in malignant cells are of potential importance as markers of tumor proliferation. Twenty such proteins were identified, ten constituting novel identifications and ten sequence verifications of previously gel-matched proteins. The proteins identified span a wide range of functions, but several cases of protein truncation were found. Truncated forms of cytokeratins 6D and 8, and of cathepsin D were identified. Truncated froms of these over-expressed proteins support the presence of proteolytic processing steps in tumor material. The protein processing and the difference between protein and mRNA abundancies in tumors of different malignancy and origin suggest that studies at the protein level are important for an understanding of tumor phenotypes.     

Lipid bilayers on polyacrylamide brushes for inclusion of membrane proteins

The ability of neutral polymer cushions to support neutral lipid bilayers for the incorporation of mobile transmembrane proteins was investigated. Polyacrylamide brush layers were grown on fused silica using atom-transfer radical polymerization to provide polymer layers of 2.5-, 5- and 10-nm thickness. Lipid bilayers composed of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) were formed by vesicle fusion onto bare fused silica and onto each of the polyacrylamide layers. Bilayer fluidity was assessed by the diffusion of a probe, NBD-labeled phosphatidylcholine, using fluorescence recovery after photobleaching. A transmembrane protein, the human delta-opioid receptor, was inserted into each lipid bilayer, and its ability to bind a synthetic ligand, DPDPE, cyclic[2-d-penicillamine, 5-d-penicillamine]enkephalin, was detected using single-molecule fluorescence spectroscopy by labeling this ligand with a rhodamine dye. The transmembrane protein was observed to bind the ligand for all bilayers tested. The protein's electrophoretic mobility was probed by monitoring the fluorescence from the bound ligand. The 5-nm polyacrylamide thickness gave the fastest diffusion for the fluorescent lipid probe (D(1) = 2.0(+/-1.2) x 10(-7) and D(2) = 1.2(+/-0.5) x 10(-6) cm(2)/s) and also the largest electrophoretic mobility for the transmembrane protein (3 x 10(-8) cm(2)/V.s). The optimum in polymer thickness is suggested to be a tradeoff between decoupling from the substrate and increasing roughness of the polymer surface.     

Methyldixanthogenatostibane

Methyldixanthatostibanes Methyldixanthatostibanes CH₃Sb(S₂COR)₂ are obtained either by reacting sodium xanthates with methyldibromostibanes at low temperatures (?78°C) or by insertion of CS₂ in methyldialkoxistibanes. An X-ray analysis of CH₃Sb(S₂COC₂H₅)₂ is given. It shows that in the crystal the Sb atom is chelated fivefold — inter and intramolecular — by sulfur atoms, so that a pentagonal pyramidal or pentagonal bipyramidal, with inclusion the lone pair, geometry is observed.     

Structure and Synthesis of (±)-Caudoxirene,a New Spermatozoid-Releasing and -Attracting Pheromone from the Marine Brown Alga Perithalia caudata (Phaeophyceae,Sporochnales). Part V

Cis-3-(trans-1,2-Epoxybut-3-enyl)-4-vinylcyclopentene ((±)- 4 , caudoxirene) is a new gamete-releasing and gamete-attracting pheromone from the marine brown alga Perithalia caudata (Sporochnales). The key step of its synthesis is the diastereoselective alkylation of the aldehyde 8 with the [(phenylthio)allyl]titanium reagent 9 to yield the erythro-β-hydroxy sulfide 10 which affords 4 on sequential treatment with Me₃O·BF₄ and aq. NaOH. The lowest effective concentration of (±)- 4 for gamete-release is found at 1.4 × 10^?11 mol/l seawater.     

Trennung von Gasen durch Sorptionsvorgänge. II

Zusammenfassung In Fortsetzung einer früheren Arbeit¹, in der Versuche über die Trennung verschiedener binärer Gasgemische an Aktivkohle nach einem dort näher beschriebenen Verfahren durchgeführt worden sind, wird das Verhalten der gleichen Gasmischungen an Silikagel untersucht. Weiters wird noch die Trennung der Systeme N₂–O₂ und C₂H₆–C₂H₄–C₂H₂–CO₂ an Aktivkohle und Silikagel besprochen. Maßnahmen zur Erhöhung der Trennschärfe und die analytische Anwendung des Verfahrens werden erörtert und eine Vakuumapparatur für das Arbeiten mit Gasen wird beschrieben.Mit 7 Abbildungen