Resveratrol augments ER stress and the cytotoxic effects of glycolytic inhibition in neuroblastoma by downregulating Akt in a mechanism independent of SIRT1

Cancer cells typically display increased rates of aerobic glycolysis that are correlated with tumor aggressiveness and a poor prognosis. Targeting the glycolytic pathway has emerged as an attractive therapeutic route mainly because it should spare normal cells. Here, we evaluate the effects of combining the inhibition of glycolysis with application of the polyphenolic compound resveratrol (RSV) in neuroblastoma (NB) cancer cell lines. Inhibiting glycolysis with 2-deoxy-D-glucose (2-DG) significantly reduced NB cell viability and was associated with increased endoplasmic reticulum (ER) stress and Akt activity. Administration of 2-DG increased the expression of the ER molecular chaperones GRP78 and GRP94, the prodeath protein C/EBP homology protein (CHOP) and the phosphorylation of Akt at S473, T450 and T308. Combined treatment with both RSV and 2-DG reduced GRP78, GRP94 and Akt phosphorylation but increased CHOP and NB cell death when compared with the administration of 2-DG alone. The selective inhibition of Akt activity also decreased 2-DG-induced GRP78 and GRP94 expression and increased CHOP expression, suggesting that Akt can modulate ER stress. Protein phosphatase 1α (PP1α) was activated by RSV, as indicated by a reduction in PP1α phosphorylation at T320. Pretreatment of cells with tautomycin, a selective PP1α inhibitor, prevented the RSV-mediated decrease in Akt phosphorylation, suggesting that RSV enhances 2-DG-induced cell death by activating PP1 and downregulating Akt. The RSV-mediated inhibition of Akt in the presence of 2-DG was not prevented by the selective inhibition of SIRT1, a known target of RSV, indicating that the effects of RSV on this pathway are independent of SIRT1. We propose that RSV inhibits Akt activity by increasing PP1α activity, thereby potentiating 2-DG-induced ER stress and NB cell death.     

In vitro and in vivo studies of N,N′-bis[2(2-pyridyl)-methyl]pyridine-2,6-dicarboxamide–copper(II) and rheumatoid arthritis

The thermodynamic equilibria of copper(II), zinc(II) and calcium(II) with N,N′-bis[2(2-pyridyl)-methyl]pyridine-2,6-dicarboxamide (L1) have been studied at 25 °C and an ionic strength of 0.15 mol dm⁻³. Spectroscopic studies suggest metal ion complexation promotes deprotonation and coordination of the amide nitrogens resulting in overall tetragonal coordination of Cu²⁺. Blood–plasma modelling predicts that Cu(II) competes effectively against Zn(II) and Ca(II) for L1 in vivo. Octanol–water partition coefficient studies show that Cu(II)–L1 complexes are reasonably lipophilic. However, the CuL1H₋₂ species which predominates at the physiological pH of 7.4 has poor superoxide dismutase activity. Bio-distribution experiments showed activity accumulation and retention in the body of about 50% of the injected dose for the [⁶⁴Cu]Cu(II)–L1 complex after 24 h.     

Thermal stability of artinite, dypingite and brugnatellite—Implications for the geosequestration of green house gases

The approach to remove green house gases by pumping liquefied carbon dioxide several kilometres below the ground implies that many carbonate containing minerals will be formed. Among these minerals the formation of dypingite, artinite and if the ferric iron is present brugnatellite are possible; thus necessitating a study of the thermal stability of such minerals. The thermal stability of two carbonate bearing minerals dypingite and artinite together with brugnatellite with a hydrotalcite related formulae have been characterised by a combination of thermogravimetry and evolved gas mass spectrometry. Artinite is thermally stable up to 352 °C. Two mass loss steps are observed at 219 and 355 °C. Dypingite decomposes at a similar temperature but over a large number of steps. Brugnatellite shows greater stability with decomposition not occurring until after 577 °C. The thermal decomposition of brugnatellite occurs over a number of mass decomposition steps. It is concluded that pumping liquefied green house gases into magnesium bearing mineral deposits is feasible providing a temperature of 350–355 °C is not exceeded to prevent escape of CO₂ towards the surface. In contrast, the water loss occurring at lower temperatures could have a positive effect on the geosequestration of CO₂ as it probably causes a decrease in the molar volume of secondary carbonate minerals and consequently an increase in aquifer porosity.     

Quantitative SERRS for DNA sequence analysis

SERRS is an extremely sensitive and selective technique which when applied to the detection of labelled DNA sequences allows detection limits to be obtained which rival, and in most cases are better than, fluorescence. In this tutorial review the conditions are explored which enable the successful detection of DNA using SERRS. The enhancing surface which is used is crucial and in this case suspensions of nanoparticles were the focus as they allow quantitative behaviour to be achieved in systems analogous to current fluorescence based approaches. The aggregation conditions required to obtain SERRS of DNA affect the sensitivity and the reproducibility and we describe the use of spermine as an effective aggregating agent to achieve excellent reproducibility and sensitivity. The nature of the label which is used, be it fluorescent or non-fluorescent, positively or negatively charged, also affects the SERRS response and these conditions are again discussed. Finally, we show how to detect a specific target DNA sequence in a meaningful diagnostic assay using SERRS and how the approaches described previously in the review are vital to the success of such approaches.     

Directed assembly of single-walled carbon nanotubes via drop-casting onto a UV-patterned photosensitive monolayer

We report the use of a novel UV-sensitive self-assembled monolayer to selectively deposit single-walled carbon nanotubes from solution using heterogeneous surface wettability. This process combines ubiquitous photopatterning techniques with simple solution processing to yield highly selective and densely packed carbon nanotube patterns. The essential concept behind this process is the change in surface chemistry caused by the UV-induced monolayer reaction. Selective deposition of carbon nanotubes was achieved by drop-casting, and the resulting films show local ordering, indicating that further development of this process will lead to simple technique for large-scale integration.     

A high-affinity metal-binding peptide from Escherichia coli HypB

The high-affinity nickel-binding site of the Escherichia coli [NiFe]-hydrogenase accessory protein HypB was localized to residues at the immediate N-terminus of the protein. Modification of a metal-binding fusion protein, site-directed mutagenesis experiments, and DFT calculations were used to identify the N-terminal amine as a ligand as well as the three cysteine residues in the CXXCGCXXX motif. This sequence can be removed from the protein and both a synthesized peptide and a protein fusion bind nickel with a similar affinity and the same structure as the parent metalloprotein, indicating the self-sufficiency of this high-affinity nickel-binding sequence.     

Facile and selective aliphatic C-H bond activation at ambient temperatures initiated by Cp*W(NO)(CH2CMe3)(eta(3)-CH2CHCHMe)

Thermolysis of Cp*W(NO)(CH2CMe3)(eta(3)-CH2CHCHMe) (1) at ambient temperatures leads to the loss of neopentane and the formation of the eta(2)-diene intermediate, Cp*W(NO)(eta(2)-CH2=CHCH=CH2) (A), which has been isolated as its 18e PMe3 adduct. In the presence of linear alkanes, A effects C-H activations of the hydrocarbons exclusively at their terminal carbons and forms 18e Cp*W(NO)(n-alkyl)(eta(3)-CH2CHCHMe) complexes. Similarly, treatments of 1 with methylcyclohexane, chloropentane, diethyl ether, and triethylamine all lead to the corresponding terminal C-H activation products. Furthermore, a judicious choice of solvents permits the C-H activation of gaseous hydrocarbons (i.e., propane, ethane, and methane) at ambient temperatures under moderately elevated pressures. However, reactions between intermediate A and cyclohexene, acetone, 3-pentanone, and 2-butyne lead to coupling between the eta(2)-diene ligand and the site of unsaturation on the organic molecule. For example, Cp*W(NO)(eta(3),eta(1)-CH2CHCHCH2C(CH2CH3)2O) is formed exclusively in 3-pentanone. When the site of unsaturation is sufficiently sterically hindered, as in the case of 2,3-dimethyl-2-butene, C-H activation again becomes dominant, and so the C-H activation product, Cp*W(NO)(eta(1)-CH2CMe=CMe2)(eta(3)-CH2CHCHMe), is formed exclusively from the alkene and 1. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by X-ray crystallographic analyses. Finally, the newly formed alkyl ligands may be liberated from the tungsten centers in the product complexes by treatment with iodine. Thus, exposure of a CDCl3 solution of the n-pentyl allyl complex, Cp*W(NO)(n-C5H11)(eta(3)-CH2CHCHMe), to I2 at -60 degrees C produces n-C5H11I in moderate yields.     

Thermal formation of mixed-metal inorganic complexes at atmospheric pressure

Atmospheric-pressure thermal desorption ionization (APTDI), a new variant on older ionization methods, is employed to generate gas-phase ions from inorganic and organometallic compounds. The method is compared to conventional electrospray ionization (ESI) of these compounds and found in most cases examined to yield simpler mass spectra which are useful in the characterization of the pure compounds. Cluster formation, however, is prominent in these spectra and mixtures of V(IV)O(salen), Ni(II)(salen) and Co(II)(salen) show mixed-metal cluster ions. This makes APTDI a way to prepare gas-phase ions which contain multiple selected metal atoms and ligands. Such mixed-metal complexes can be mass-selected and structurally characterized by tandem mass spectrometry. Strong contrasts are evident in the dissociation behavior of homonuclear and heteronuclear metal clusters, the latter showing accompanying redox processes. The chemical reactivity accompanying collision-induced dissociation (CID) of some of the mixed-metal clusters is typified by the protonated species H+[NiVO(salen)], which undergoes a formal oxidation process (hydrogen atom loss) to give the molecular radical cation of Ni(salen). This ionization method may provide a new route to unique inorganic compounds on surfaces through soft landing of appropriate cluster ions. The contrasting behavior of the ESI and APTDI processes is evident in the salens where ESI shows simple Bronsted acid/base chemistry, no mixed-metal clusters and no redox chemistry.     

Internal energy distributions in desorption electrospray ionization (DESI)

The internal energy distributions of typical ions generated by desorption electrospray ionization (DESI) were measured using the "survival yield" method, and compared with corresponding data for electrospray ionization (ESI) and electrosonic spray ionization (ESSI). The results show that the three ionization methods produce populations of ions having internal energy distributions of similar shapes and mean values (1.7-1.9 eV) suggesting similar phenomena, at least in the later stages of the process leading from solvated droplets to gas-phase ions. These data on energetics are consistent with the view that DESI involves "droplet pick-up" (liquid-liquid extraction) followed by ESI-like desolvation and gas-phase ion formation. The effects of various experimental parameters on the degree of fragmentation of p-methoxy-benzylpyridinium ions were compared between DESI and ESSI. The results show similar trends in the survival yields as a function of the nebulizing gas pressure, solvent flow rate, and distance from the sprayer tip to the MS inlet. These observations are consistent with the mechanism noted above and they also enable the user to exercise control over the energetics of the DESI ionization process, through manipulation of external and internal ion source parameters.