Genomic cloning and protein expression of a novel rat brain cytochrome P-450 CYP2D18* catalyzing imipramine N-demethylation

We have previously reported the isolation of two cDNA clones, designated 2d-29 and 2d-35, which have identical open reading frames and code for a novel brain cytochrome P-450 (P-450) belonging to the CYP2D subfamily, and noted that the mRNA of clone 2d-35 seems to be expressed in the brain but not in the liver (1). Although the deduced amino acid sequence of these clones differs from that of the liver CYP2D4 by only 5 amino acids distributed in the C-terminal region, this new P-450 cDNA clone contained a unique 5'-extension, and we posit in this report by analysis of a genomic clone that this 5'-untranslated sequence is derived from a gene distinct from that of CYP2D4. Thus, this novel P-450 was named P-450 2D18 according to the recommended nomenclature (2). The expressibility of this cDNA was confirmed by in vitro translation using a reticulocyte system, and protein expression was performed using COS-M6 cells. Immunoblot analysis showed a cross-reacting band of the predicted size range with anti-P-450 2D6 antiserum, which was not seen in control cells. Furthermore, the CYP2D18-expressed COS cell lysate showed N-demethylation activity toward imipramine, whereas another brain P-450 CYP4F6-expressed COS cell lysate showed 10-hydroxylation activity. This is the first report that associates an individual P-450 isozyme in brain with a particular metabolic alteration of the antidepressant imipramine.     

Electrochemical development of hydrogen silsesquioxane by applying an electrical potential

We present a new method for developing hydrogen silsesquioxane (HSQ) by using electrical potentials and deionized water. Nested-L test structures with a pitch as small as 9 nm were developed using this electrochemical technique in saline solution without adding hydroxyl ions. Furthermore, we showed that high-resolution structures can be electrochemically developed in deionized water alone. Electrochemical development is controlled by the applied voltage and may overcome several of the limitations discussed for alkaline developers, such as poor hydroxyl anion diffusion and charge repulsion effects in small trenches.     

Contact angle measurements on oxidized polymer surfaces containing water-soluble species

Advancing and receding contact angle measurements on polymer surfaces can be performed using a number of different methods. Ballistic deposition is a new method for both rapidly and accurately measuring the receding contact angle of water. In the ballistic deposition method, a pulsed stream of 0.15-μL water droplets is impinged upon a surface. The water spreads across the surface and then coalesces into a single 1.8-μL drop. High-speed video imaging shows that, on most surfaces, the water retracts from previously wetted material, thereby forming receding contact angles that agree with the receding angles measured by the Wilhelmy plate technique. The ballistic deposition method measures the receding angle within one second after the water first contacts the surface. This rapid measurement enables the investigation of polymer surface properties that are not easily probed by other wettability measurement methods. For example, meaningful contact angles of water can be obtained on the water-soluble low-molecular-weight oxidized materials (LMWOM) formed by the corona and flame treatment of polypropylene (PP) films. Use of the ballistic deposition method allows for a characterization of the wetting properties and an estimation of the surface energy components of LMWOM itself. Both corona- and flame-generated LMWOM have significant contact angle hysteresis, almost all of which is accounted for by the non-dispersive (polar) component of the surface rather than by the dispersive component. Surface heterogeneity is thus associated primarily with the oxidized functionalities added to the PP by the corona and flame treatments.     

Metal-Free Hydrogen-Bonded Polymers Mimic Noble Metal Electrocatalysts

The most active and efficient catalysts for the electrochemical hydrogen evolution reaction (HER) rely on platinum, a fact that increases the cost of producing hydrogen and thereby limits the widespread adoption of this fuel. Here, a metal-free organic electrocatalyst that mimics the platinum surface by implementing a high work function and incorporating hydrogen-affine hydrogen bonds is introduced. These motifs, inspired from enzymology, are deployed here as selective reaction centres. It is shown that the keto-amine hydrogen-bond motif enhances the rate-determining step in proton reduction to molecular hydrogen. The keto-amine-functionalized polymers reported herein evolve hydrogen at an overpotential of 190 mV. They share certain key properties with platinum: a similar work function and excellent electrochemical stability and chemical robustness. These properties allow the demonstration of one week of continuous HER operation without notable degradation nor delamination from the carrier electrode. Scaled continuous-flow electrolysis is reported and 1 L net molecular hydrogen is produced within less than 9 h using 2.3 mg of polymer electrocatalyst.     

Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection. It is capable of separating and quantifying both C8-isomers of ergocornine, alpha-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61% +/- 10% with limits of detection from 0.2 to 1.1 microg kg(-1). Twenty-four unknown rye flour samples from Danish mills contained on average 46 microg kg(-1) with a maximum content of 234 microg kg(-1). The most common ergot alkaloids were ergotamine and alpha-ergocryptine including their C8-isomers. A total of 54% of the ergot alkaloids were detected as C(8)-S isomers.     

Sub-10 nm structures on silicon by thermal dewetting of platinum

A study of the dewetting behavior of platinum-thin-films on silicon was carried out to determine how variation of dewetting parameters affects the evolution of film morphology and to pinpoint which parameters yielded the smallest, most circular features. Platinum film thickness as well as dewetting time and temperature were varied and the film morphology characterized by means of scanning electron microscopy (SEM) analysis. Two different pathways of dewetting predicted in the literature (Vrij 1966 Discuss. Faraday Soc. 42 23, Becker et al 2003 Nat. Mater. 2 59-63) were observed. Depending on the initial criteria, restructuring of the film occurred via hole or droplet formation. With increased annealing time, a transition from an intermediate network structure to separated islands occurred. In addition, the formation of multilayered films, silicide crystals and nanowires occurred for certain parameters. Nevertheless, the dewetting behavior witnessed could be related to physical processes. Droplets with a mean diameter of 9 nm were formed by using a 1.5 nm thick platinum film annealed at 800?°C for 30 s. To demonstrate the suitability of the annealed films for further processing, we then used the dewetted films as masks for reactive ion etching to transfer the pattern into the silicon substrate, forming tapered nanopillars.     

Crystal growth of Ti n O2n-1 oxides(n=2 to 9)

Crystals of titanium oxides, Ti _n O_2n-1 with n=2 to 9, were grown by chemical vapour transport. Chlorine was found to be the best transporting agent. Apart from Ti₂O₃, for which crystals up to 7 mm long were obtained in 6 days, all phases were obtained in conditions leading to very low growth rates and a shift in composition between the charge and growth zones. It is shown that this shift is governed by the equilibrium oxygen pressure in the transport tubes and can be accurately predicted. Most of the millimetresize samples obtained were twinned.     

Trace concentrations of halothane in human breast milk

Halothane concentrations of 2 p.p.m. have been found in the breast milk of a lactating, practising anaesthetist. This concentration was consistent with the operating theatre environment. The authors fell that, in spite of the limited scope of the study, this is an additional reason for the elimination of waste anaesthetic agents from the operating theatre.