Важливе історико-географічне дослідження

Рец. на кн. Темушева В.Н. "Гомельская земля в конце XV первой половине XVI в. Территориальные трансформации в пограничном регионе". — М.: "Квадрига", 2009. — 190 с.Review of the book: Temushev V.N. "Gomel Land in the Late 15th — the 1st half of the 16th Centuries. Territorial Transformations in the Frontier Area". — Moscow: "Kvadriga", 2009. — 190 p

Synthetic Analogue of Stilbene Containing an Imidazole Nucleus

Synthesis of trans-1,2-bis(4-nitro-1-p-methoxybenzylimidazol-5-yl)ethene (1) as an imidazole analogue of stilbene has been reported. In order to confirm the trans geometry of the product using an UV spectral comparison, a mixture of both trans (1) and cis isomer (3) was also prepared. The synthesis involved one-step dimerization of the precursor, 4-nitro-1-p-methoxybenzyl-5-methyl-1H-imidazole (2), using N-chlorosuccinimide catalyzed by potassium t-butoxide

Synthesis of 1-(2\u27-Deoxy-ß-D-ribofuranosyl)-1H-imidazo[4,5-d]-pyridazine-4,7(5H,6H)-dione: A Potential Building Block for Antisense Applications

Synthesis of the title compound,1-(2\u27-deoxy-b-D-ribofuranosyl)-1H-imidazo[4,5-d]pyridazine-4,7(5H,6H)-dione (1), is reported. It was synthesized in five steps, commencing with methyl 1-(b-D-ribofuranosyl)imidazo-4,5-dicarboxylate (2). The 3\u27,5\u27-hydroxyl groups of 2 were protected with a bis-silylating agent to form 3, which was then converted into the corresponding 2\u27-thionocarbonate derivative 5. The reduction of the latter with tri-n-butyltin hydride (to form 6), followed by silyl deprotection with tetra-nbutylammonium fluoride, afforded 7. Treatment of the latter with hydrazine hydrate yielded the target nucleoside 1

Synthesis of 1-(2'-O-Methyl-ß-D-ribofuranosyl)-1H-imidazo[4,5-d]pyridazine-4,7(5H,6H)-dione: An Attractive Building Block for Antisense and Triple-helical Applications

Synthesis of the title compound,1-(2'-O-methyl-ß-D-ribofuranosyl)-1H-imidazo-[4,5-d]pyridazine-4,7(5H,6H)-dione (1), is reported. It was synthesized in four steps, starting from methyl 1-(ß-D-ribofuranosyl)imidazo-4,5-dicarboxylate (2). The 3',5'-hydroxyl groups of 2 was protected with a bis-silylating agent to form 3, which was then methylated to form the corresponding 2'-O-methyl derivative 5. The silyl deprotection of the latter (to form 6), followed by treatment with hydrazine afforded the target nucleoside 1. The reported nucleoside has potentially beneficial applications in biomedicine based on antisense and triple-helical nucleic acid technologies

Synthesis of 1-(2\u27-O-Methyl-ß-D-ribofuranosyl)-1H-imidazo[4,5-d]pyridazine-4,7(5H,6H)-dione: An Attractive Building Block for Antisense and Triple-helical Applications

Synthesis of the title compound,1-(2\u27-O-methyl-ß-D-ribofuranosyl)-1H-imidazo-[4,5-d]pyridazine-4,7(5H,6H)-dione (1), is reported. It was synthesized in four steps, starting from methyl 1-(ß-D-ribofuranosyl)imidazo-4,5-dicarboxylate (2). The 3\u27,5\u27-hydroxyl groups of 2 was protected with a bis-silylating agent to form 3, which was then methylated to form the corresponding 2\u27-O-methyl derivative 5. The silyl deprotection of the latter (to form 6), followed by treatment with hydrazine afforded the target nucleoside 1. The reported nucleoside has potentially beneficial applications in biomedicine based on antisense and triple-helical nucleic acid technologies

Identification of Small Molecules That Suppress MicroRNA Function and Reverse Tumorigenesis*

MicroRNAs (miRNAs) act in post-transcriptional gene silencing and are proposed to function in a wide spectrum of pathologies, including cancers and viral diseases. Currently, to our knowledge, no detailed mechanistic characterization of small molecules that interrupt miRNA pathways have been reported. In screening a small chemical library, we identified compounds that suppress RNA interference activity in cultured cells. Two compounds were characterized; one impaired Dicer activity while the other blocked small RNA-loading into an Argonaute 2 (AGO2) complex. We developed a cell-based model of miRNA-dependent tumorigenesis, and using this model, we observed that treatment of cells with either of the two compounds effectively neutralized tumor growth. These findings indicate that miRNA pathway-suppressing small molecules could potentially reverse tumorigenesis

Characterization of Imidazo[4,5-d]Pyridazine Nucleosides as Modulators of Unwinding Reaction Mediated by West Nile Virus Nucleoside Triphosphatase/Helicase: Evidence for Activity on the Level of Substrate and/or Enzyme

Compounds that interact with DNA or RNA generally act as inhibitors of enzymes that unwind DNA or RNA. In the present study we describe the synthesis and properties of some nucleoside analogues that interact with double-stranded DNA but that, in contrast, facilitate the unwinding reaction mediated by West Nile (WN) virus nucleoside triphosphatase (NTPase)/helicase. The nucleoside analogues described, 1-(2′-O-methyl-β-d-ribofuranosyl)imidazo[4,5-d]pyridazine-4,7(5H,6H)-dione (HMC-HO4), 1-(β-d-ribofuranosyl)imidazo[4,5-d]pyridazine-4,7(5H,6H)-dione, and 1-(2′-deoxy-α-d-ribofuranosyl)imidazo[4,5-d]pyridazine-4,7(5H,6H)dione, all contain the imidazo[4,5-d]pyridazine ring system. The extent of the enhancing effect on helicase activity was found to be dependent on the time of exposure of the DNA substrate to the compounds and their concentrations. The nucleoside analogues were nevertheless found to be capable of uncoupling the ATPase and helicase activities of the enzyme by a mechanism operating on the level of the enzyme. Thus, in the case of HMC-HO4, the direct interaction with the enzyme caused inhibition of its helicase activity, with a half-maximal inhibitory concentration of 30 μM. The similar potency of the compound against replication of WN virus in cell culture suggests that inhibition of the helicase activity of the viral enzyme is responsible for the observed antiviral activity of HMC-HO4 and may indeed represent an important mode of action of antiviral drugs in general. Comparative studies performed with the related NTPase/helicase from hepatitis C virus revealed that the extent of the effects mediated by imidazo[4,5-d]pyridazine nucleosides is enzyme specific. The substances described may represent a starting point for the development of a new class of helicase-specific antivirals