Effect of plasmochemical treatment of platinum catalyst on dispersity of metal phase and its catalytic activity

We studied how treatment of 0.64 wt % Pt/SiO₂ catalyst with a glow-discharge plasma in O₂ and a high-frequency plasma in H₂ (HF H₂) influences the cyclohexane dehydrogenation reaction. The effect of plasmochemical treatment on the average diameter of platinum particles was established by the method of X-ray diffraction analysis. It was found that oxygen plasma increases the surface area of the metal by ∼15% and diminishes activity by raising the activation energy and reducing the number of active centers per unit surface of the metal. The HF H₂ plasma increases the reaction rate constant many times over, due to the number of active centers per unit surface of the metal rising sharply while the size of the Pt particles remains unchanged.     

Disproportionation rate and products of cyclohexylperoxy radicals

Conclusions The pulse photolysis method was used to measure the rate constant for the disproportionation of cyclohexylperoxy radicals at 12–60°; the practically sole products of this reaction are cyclohexanol and cyclohexanone, which are formed in approximately equal amounts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 631–634, March, 1979.     

Hemichrome Determination by Thermal Lensing with Polyethylene Glycols for Signal Enhancement in Aqueous Solutions

The thermal lens technique is proposed for the determination of total hemoglobin in the form of reversible hemichrome. The conditions were optimized (concentration of sodium dodecyl sulfate, 2?mM) to attain the maximum sensitivity with the use of polyethylene glycols as signal enhancers. For polyethylene glycols with molecular weights 1500–35000 Da in a concentration range of 5–15% w/w (5–25?mM), the influence on thermal lens signal enhancement was estimated. It is shown that the use of 5% w/w polyethylene glycol 2000 provides the maximum increase in the thermal lens enhancement factor (by 40%) in comparison with unmodified aqueous solutions. The detection limit of iron(II) tris(1,10-phenanthrolinate) as a model system is 60?nM. Under these conditions, the thermal lens detection limit of hemichrome is 10?nM, which shows a 15-fold enhancement compared to spectrophotometry. Modification of the medium with polyethylene glycols decreases the limit of detection of hemichrome determination by 15% in comparison with unmodified aqueous solutions due to better reproducibility for the range of concentrations from 0.02 to 0.9?µM.     

In Vitro Evaluation of the Cytotoxic Effect of Streptococcus pyogenes Strains,Protegrin PG-1, Cathelicidin LL-37, Nerve Growth Factor and Chemotherapy on the C6 Glioma Cell Line

Brain cancer treatment, where glioblastoma represents up to 50% of all CNS malignancies, is one of the most challenging calls for neurooncologists. The major driver of this study was a search for new approaches for the treatment of glioblastoma. We tested live S. pyogenes, cathelicidin family peptides and NGF, assessing the oncolytic activity of these compounds as monotherapy or in combination with chemotherapeutics. For cytotoxicity evaluation, we used the MTT assay, trypan blue assay and the xCELLigence system. To evaluate the safety of the studied therapeutic approaches, we performed experiments on normal human fibroblasts. Streptococci and peptides demonstrated high antitumor efficiency against glioma C6 cells in all assays applied, surpassing the effect of chemotherapeutics (doxorubicin, carboplatin, cisplatin, etoposide). A real-time cytotoxicity analysis showed that the cell viability index dropped to 21% 2–5 h after S. pyogenes strain exposure. It was shown that LL-37, PG-1 and NGF also exhibited strong antitumor effects on C6 glioma cells when applied at less than 10⁻⁴ M. Synergistic effects for combinations of PG-1 with carboplatin and LL-37 with etoposide were shown. Combinations of S. pyogenes strain #7 with NGF or LL-37 demonstrated a cytotoxic effect (56.7% and 57.3%, accordingly) on C6 glioma cells after 3 h of exposure.     

Reaction of levoglucosenone with Dane’s diene

Cycloaddition of levoglucosenone to 7-methoxy-4-vinyl-1,2-dihydronaphthalene has been studied under different conditions, including heating under atmospheric pressure, in a sealed ampule, and under high pressure, as well as under microwave irradiation and in the presence of various catalysts. The chiral Diels–Alder adduct thus obtained can be used in the synthesis of estrone and its analogs.     

Ionic liquids in enzymatic catalysis and biochemical methods of analysis: Capabilities and prospects

The first Russian review systematizes and discusses the most important and promising published data on the use of ionic liquids in biocatalysis and, especially, biochemical methods of analysis. Studies on the use of ionic liquids as solvents for enzymes, new reaction media for enzymatic reactions, and components of the biosensitive layers of sensors are analyzed. The physical and chemical properties of ionic liquids used in biocatalysis are discussed. The advantages of ionic liquids over the usual solvents in homogeneous and heterogeneous reactions with the participation of enzymes from various classes are demonstrated, procedures for the coimmobilization of biocatalysts and ionic liquids with cellulose onto polymer supports and electrodes are described, and prospects for the use of enzyme-ionic liquid compositions in biochemical methods of analysis are considered.     

Dzhemilev reaction in the synthesis of five-membered sulfur and selenium heterocycles*

A one-pot methods were developed for the synthesis of five-membered sulfur and selenium heterocycles based on the consecutive cyclometallation of olefins, allenes, and acetylenes using alkyl and haloalkyl derivatives of Al and Mg in the presence of catalytic amounts of titanium and zirconium complexes to give the corresponding alumina- and magnesacarbocycles in situ, which, without further purification, were introduced into reaction with sulfur or selenium, leading to various tetrahydrothiophenes, thiophenes, tetrahydroselenophenes, and selenophenes. * Dedicated to Academician B. A. Trofimov of the Russian Academy of Sciences on the occasion of his seventieth jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 393–403, March, 2009.     

Anticancer Effect of Cathelicidin LL-37, Protegrin PG-1, Nerve Growth Factor NGF,and Temozolomide: Impact on the Mitochondrial Metabolism,Clonogenic Potential,and Migration of Human U251 Glioma Cells

Glioblastoma (GBM) is one of the most aggressive and lethal malignancy of the central nervous system. Temozolomide is the standard of care for gliomas, frequently results in resistance to drug and tumor recurrence. Therefore, further research is required for the development of effective drugs in order to guarantee specific treatments to succeed. The aim of current study was to investigate the effects of nerve growth factor (NGF), human cathelicidin (LL-37), protegrin-1 (PG-1), and temozolomide on bioenergetic function of mitochondria, clonogenicity, and migration of human U251 glioma cells. Colony formation assay was used to test the ability of the glioma cells to form colonies in vitro. The U251 glioma cells migration was evaluated using wound-healing assay. To study the mitochondrial metabolism in glioma cells we measured oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) using a Seahorse XF cell Mito stress test kit and Seahorse XF cell Glycolysis stress kit, respectively. We revealed that LL-37, NGF, and TMZ show strong anti-tumorigenic activity on GMB. LL-37 (4 μM), TMZ (155 μM), and NGF (7.55 × 10⁻³ μM) inhibited 43.9%–60.3%, 73.5%–81.3%, 66.2% the clonogenicity of glioma U251 cells for 1–2 days, respectively. LL-37 (4 μM), and NGF (7.55 × 10⁻³ μM) inhibited the migration of U251 glioma cells on the third and fourth days. TMZ also inhibited the migration of human glioma U251 cells over 1–3 days. In contrast, PG-1 (16 μM) stimulated the migration of U251 glioma cells on the second, fourth, and sixth days. Anti-mitogenic and anti-migration activities of NGF, LL-37, and TMZ maybe are relation to their capacity to reduce the basal OCR, ATP-synthetase, and maximal respiration of mitochondria in human glioma U251 cells. Glycolysis, glycolytic capacity and glycolytic spare in glioma U251 cells haven`t been changed under the effect of NGF, LL-37, PG-1, and TMZ in regard to control level. Thus, LL-37 and NGF inhibit migration and clonogenicity of U251 glioma cells, which may indicate that these compounds have anti-mitogenic and anti-migration effects on human glioma cells. The study of the mechanisms of these effects may contribute in the future to the use of NGF and LL-37 as therapeutic agents for gliomas.