Primary photodamage sites and mitochondrial events after Foscan photosensitization of MCF-7 human breast cancer cells

To determine the initial photodamage sites of Foscan-mediated photodynamic treatment, we evaluated the enzymatic activities in selected organelles immediately after light exposure of MCF-7 cells. The measurements indicated that the enzymes located in the Golgi apparatus (uridine 5'-diphosphate galactosyl transferase) and in the endoplasmic reticulum (ER) (nicotinamide adenine dinucleotide [reduced] [NADH] cytochrome c [cyt c] reductase) are inactivated by the treatment, whereas mitochondrial marker enzymes (cyt c oxidase and dehydrogenases) were unaffected. This indicates that the ER and the Golgi apparatus are the primary intracellular sites damaged by Foscan-mediated PDT in MCF-7 cells. We further investigated whether the specific mitochondria events could be associated with Foscan photoinduced cell death. The dose response profiles of mitochondrial depolarization and cytochrome c release immediately after Foscan-based PDT were very different from that of overall cell death. By 24 h post-PDT the fluence dependency was strikingly similar for both mitochondrial alterations and cell death. Therefore, although mitochondria are not directly affected by the treatment, they can be strongly implicated in Foscan-mediated MCF-7 cell death by late and indirect mechanism.     

On pathwise behavior of multiserver queues

In this paper, by exploiting recent results on the pathwise behavior of the workload process in single server, work conserving queues of theG/G/1/ type, we show that the workload of multiserver, work conserving queues ofG/G/m/ (m<) (andG/G/) queues satisfies an o(t) growth condition, provided that the time average of the work brought into the system is less thanm form < (and finite form=).     

Photochemical cycloaddition reactions of cyanoacetylene and dicyanoacetylene.

Photolysis of cyanoacetylene with 185- or 206-nm light yields 1,3,5-tricyanobenzene while 254-nm radiation yields a mixture of tetracyanocyclooctatetraenes, 1,2,4- and 1,3,5-tricyanobenzene. A polymer of cyanoacetylene is the major photoproduct. 1,3,5-Tricarbomethoxybenzene was the only photoproduct identified from the irradiation of methyl propiolate at 254 nm. Mono-, di-, and tricyanobenzenes are formed by irradiation of mixtures of acetylene and cyanoacetylene at 185, 206, and 254 nm along with trace amounts of cyclooctatetraenes. No photoadducts were detected on photolysis of mixtures of cyanoacetylene and CO or HCN. The tetracyanocyclooctatetraene structures were established by UV, MS, and NMR analyses. The 1H NMR of the product mixture exhibited a singlet at delta 7.028 consistent with either 1 or 2 and two singlets at delta 6.85 and 6.91 assigned to 3. Photolysis of mixtures of dicyanoacetylene and acetylene with either 185- or 206-nm light yielded 1,2-dicyanobenzene and (E,Z)-1-buten-3-yne-1,4-dicarbonitrile. These products were also obtained using 254-nm light along with a mixture of tetracyanocyclooctatetraenes. The same three singlets were observed in this product mixture as were observed in the tetracyanocyclooctatetraenes obtained from cyanoacetylene. From this observation it was concluded that the delta 7.02 signal is due to 2 and not 1. The photolysis of cyanoacetylene and dicyanoacetylene in the presence of ethylene with 185-nm light yields 1-cyanocylobutene and 1,2-dicyanocyclobutene, respectively. 2-Cyanobutadiene and 2,3-dicyanobutadiene are the photoproducts with 254-nm light. Reaction pathways are proposed to explain these findings.     

Photoelectron spectra of vinyl- and 1-alkynylgermanes and stannanes

Primary vinylic and acetylenic germanes and stannanes, synthesized by a chemoselective reduction of the corresponding trichloro derivatives, were investigated by ab initio quantum chemical methods and photoelectron spectroscopy. In particular, the PE spectra display very well-resolved bands which show the increasing destabilizing effect of 14 group heteroatom α-substitution of double or triple carbon–carbon bonds.     

Alkenyl selenols and selenocyanates: synthesis, spectroscopic characterization by photoelectron spectroscopy, and quantum chemical study

Vinyl, allyl, and homoallyl selenols were easily prepared by a chemoselective reduction of the corresponding selenocyanates with aluminum hydrides. Two stable vinyl and five stable allyl conformers of both series were predicted on the potential-energy surface. The interaction of SeH or SeCN groups with the vinyl group has been investigated with UV photoelectron spectroscopy and quantum chemical calculations, using the MP2/cc-pVTZ and B3LYP/cc-pVTZ levels. In the vinyl derivatives, a surprisingly strong direct conjugation of the selenium lone electron pair and the C=C double bond was observed. On the other hand, in allyl position the selenium lone pair is independent on the C=C double bond, and the hyperconjugation between the Se-C bond and the double bond is the ruling effect. Thus is clarified the type and extent of the interaction between the SeH or SeCN group and the unsaturated moiety.     

Toeplitz operators in n-dimensions

The interplay between the theory of Toeplitz operators on the circle and the theory of pseudodifferential operators on the line (i. e. Wiener-Hopf operators) is by now well-known and well-understood. In this article we show that there is a parallel situation in higher dimensions. To begin with, by using pseudodifferential multipliers, one can simplify the composition rules for Toeplitz operators, (§ 3), and describe precisely how Toeplitz operators of Bergmann type are related to Toeplitz operators of Szegö type (§ 9). Furthermore, it turns out that the ring of pseudodifferential operators on a compact manifold, M, is isomorphic with the ring of Toeplitz operators on an appropriate Grauert tube about M (§ § 4–6), and the ring of Weyl operators on ⁿ is isomorphic with the ring of Toeplitz operators on the complex ball in ⁿ (§ § 7–10).     

Séparation des isoméres de l'hexachlorocyclohexane par chromatographie en phase gaz

Hexachlorocyclohexane isomers can be separated by a glass bead technique with polypropylene glycol Niax 1025 as the stationary phase. The principal isomers separated are the γ-hexachloro-cyclohexane (Lindane isomer), the α, β, ε, and δ isomers and γ-heptachlorocyclohexane. The life of the glass bead column is short — about 20 days in constant use. A longer column life can be obtained by pretreatment of the glass beads.     

A Convenient Method for the Synthesis of α-Functionalized Chlorophosphonic Esters

α-Functionalized chlorophosphonic monoesters were easily prepared by a selective chlorination of the corresponding phosphonic diesters with phosphorus oxychloride.     

Comparison of direct mass spectrometry methods for the on‐line analysis of volatile compounds in foods

For the on‐line monitoring of flavour compound release, atmospheric pressure chemical ionization (APCI) and proton transfer reaction (PTR) combined to mass spectrometry (MS) are the most often used ionization technologies. APCI‐MS was questioned for the quantification of volatiles in complex mixtures, but direct comparisons of APCI and PTR techniques applied on the same samples remain scarce. The aim of this work was to compare the potentialities of both techniques for the study of in vitro and in vivo flavour release. Aroma release from flavoured aqueous solutions (in vitro measurements in Teflon bags and glass vials) or flavoured candies (in vivo measurements on six panellists) was studied using APCI‐ and PTR‐MS. Very similar results were obtained with both techniques. Their sensitivities, expressed as limit of detection of 2,5‐dimethylpyrazine, were found equivalent at 12 ng/l air. Analyses of Teflon bag headspace revealed a poor repeatability and important ionization competitions with both APCI‐ and PTR‐MS, particularly between an ester and a secondary alcohol. These phenomena were attributed to dependency on moisture content, gas/liquid volume ratio, proton affinities and product ion distribution, together with inherent drawbacks of Teflon bags (adsorption, condensation of water and polar molecules). Concerning the analyses of vial headspace and in vivo analyses, similar results were obtained with both techniques, revealing no competition phenomena. This study highlighted the equivalent performances of APCI‐MS and PTR‐MS for in vitro and in vivo flavour release investigations and provided useful data on the problematic use of sample bags for headspace analyses. Copyright © 2013 John Wiley & Sons, Ltd.