The pyrolysis of (−)‐(S)‐nicotine: Racemization and decomposition

The pyrolytic behaviour of (?)‐(S)‐nicotine in methanol was investigated using on‐line pyrolysis GC/MS to establish whether racemization to the R(+) antipode occurs and to identify other products of pyrolysis. The conditions used included pyrolysing the sample for 15 seconds in an atmosphere of 9% oxygen in nitrogen (275ml/min total flow) across the temperature range of 200°C–1000°C. A chiral Cyclodex‐B analytical column (30m × 0.25mm i.d. × 0.25 μm film thickness) was used to separate the enantiomers of nicotine, although the two enantiomer peaks were not baseline resolved. The results of the experiment shows that there is no increase in (+)‐(R)‐nicotine levels across a wide temperature range. This suggests that the elevated levels of (+)‐R‐nicotine observed in tobacco smoke (compared to tobacco leaf material) are not due to the pyrolytic auto‐racemization of (?)‐(S)‐nicotine but are a result of more complex interactions between (?)‐(S)‐nicotine and other smoke components. The pyrolysis of isotopically labelled nicotine established that nicotine undergoes thermal decomposition to β‐nicotyrine which in turn may decompose to other products. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

New 4,5‐seco‐20(10→5)‐abeo‐Abietane Diterpenoids with Anti‐Inflammatory Activity from Isodon lophanthoides var. graciliflorus (Benth.) H.Hara

Three new 4,5‐seco‐20(10→5)‐abeo‐abietane diterpenoids, 16‐hydroxysalvilenone ( 1 ), 15‐hydroxysalprionin ( 2 ), and 11β,15‐dihydroxysalprionin‐12‐one ( 3 ), and nine known abietane diterpenoids, 4 – 12 , along with one known sempervirane diterpenoid, hispidanol A ( 13 ), were isolated from the aerial parts of Isodon lophanthoides var. graciliflorus. The structures of compounds 1 – 3 were determined on the basis of spectroscopic methods including extensive analysis of NMR and mass spectroscopic data. All diterpenoids were tested for their TNF‐α inhibitory effects on LPS‐induced RAW264.7 cells. Compound 9 (16‐acetoxyhorminone) was the most potent with an IC₅₀ value of 3.97±0.70 μm .     

Exceptionally Enhanced Electrode Activity of (Pr,Ce)O2−δ‐Based Cathodes for Thin‐Film Solid Oxide Fuel Cells

It is shown that an electrochemically‐driven oxide overcoating substantially improves the performance of metal electrodes in high‐temperature electrochemical applications. As a case study, Pt thin films are overcoated with (Pr,Ce)O_2?δ (PCO) by means of a cathodic electrochemical deposition process that produces nanostructured oxide layers with a high specific surface area and uniform metal coverage and then the coated films are examined as an O₂‐electrode for thin‐film‐based solid oxide fuel cells. The combination of excellent conductivity, reactivity, and durability of PCO dramatically improves the oxygen reduction reaction rate while maintaining the nanoscale architecture of PCO layers and thus the performance of the PCO‐coated Pt thin‐film electrodes at high temperatures. As a result, with an oxide coating step lasting only 5 min, the electrode resistance is successfully reduced by more than 1000 times at 500 °C in air. These observations provide a new direction for the design of high‐performance electrodes for high‐temperature electrochemical cells.     

Review: Biological Effectiveness of Thermal Neutrons and 10B(n,α)7Li Reaction on Cultured Cells

There are only a few reports on the relative biological effectiveness (RBE) of thermal neutrons and ¹⁰B(n,α)⁷Li reactions either in vitro or in vivo. The data in this paper summarize almost all previously published in vitro data. Because only a few reactors are available for biomedical purposes, it is difficult to make a comparison of data from experiments using the same kind of radiation, and also to make a comparison of data from experiments using the different kinds of radiations. However, it is indispensable for boron neutron capture therapy to make a radiobiological analysis. More intensive study, including repair process and oxygen effect, is necessary for establishing the fundamental basis of the clinical application of boron neutron capture therapy.     

α4 phosphoprotein interacts with EDD E3 ubiquitin ligase and poly(A)‐binding protein

Mammalian α4 phosphoprotein, the homolog of yeast Tap42, is a component of the mammalian target‐of‐rapamycin (mTOR) pathway that regulates ribogenesis, the initiation of translation, and cell‐cycle progression. α4 is known to interact with the catalytic subunit of protein phosphatase 2A (PP2Ac) and to regulate PP2A activity. Using α4 as bait in yeast two‐hybrid screening of a human K562 erythroleukemia cDNA library, EDD (E3 isolated by differential display) E3 ubiquitin ligase was identified as a new protein partner of α4. EDD is the mammalian ortholog of Drosophila hyperplastic discs gene (hyd) that controls cell proliferation during development. The EDD protein contains a PABC domain that is present in poly(A)‐binding protein (PABP), suggesting that PABP may also interact with α4. PABP recruits translation factors to the poly(A)‐tails of mRNAs. In the present study, immunoprecipitation/immunoblotting (IP/IB) analyses showed a physical interaction between α4 and EDD in rat Nb2 T‐lymphoma and human MCF‐7 breast cancer cell lines. α4 also interacted with PABP in Nb2, MCF‐7 and the human Jurkat T‐leukemic and K562 myeloma cell lines. COS‐1 cells, transfected with Flag‐tagged‐pSG5‐EDD, gave a (Flag)‐EDD–α4 immunocomplex. Furthermore, deletion mutants of α4 were constructed to determine the binding site for EDD. IP/IB analysis showed that EDD bound to the C‐terminal region of α4, independent of the α4‐PP2Ac binding site. Therefore, in addition to PP2Ac, α4 interacts with EDD and PABP, suggesting its involvement in multiple steps in the mTOR pathway that leads to translation initiation and cell‐cycle progression. J. Cell. Biochem. 110: 1123–1129, 2010. Published 2010 Wiley‐Liss, Inc.