A mouse thymidine kinase (TK) deficient L cell subline and L cell sublines biochemically transformed by herpes simplex virus TK were cultured in the presence of increasing concentrations of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) which inhibited the growth of all sublines, and resistant sublines were isolated. Their growth properties were dependent on the medium condition used for selection. One subline had lost viral TK activity, while another retained viral TK activity with altered sensitivity of TK to BVDU in comparison with that of the original subline. Growth characteristics and TK activity of sublines are discussed.
Abstract The life-cycle of human immunodeficiency virus (HIV) begins with the binding of the viral envelope glycoprotein (gpl20) to the CD4 receptor of the host cells. Fusion between the viral envelope and the cell membrane follows, whereupon the viral nucleocapsid gains entry into the cell. After entry, uncoating of the nucleocapsid takes place. Once it has been released (at least partially) from its core (group-specific antigen (gag)) proteins, the genomic RNA is converted into double-stranded (proviral) DNA by reverse transcriptase (RT). The pro viral DNA then migrates to the nucleus where it is integrated into the host genome by integrase.
No abstract is provided for this article.
Over 50 ω-carboxyalkyl derivatives of adenine and other purine bases were examined for their inhibitory effects on rat liver S-adenosyl-L-homocysteine hydrolase and their antiviral activity. To be an inhibitor of SAH-hydrolase the analogue must contain an adenine base substituted at the position 9 by an ω-carboxyalkyl (C 3 -C 5 ) chain bearing at least one hydroxyl function. The absolute configuration at the side-chain is decisive for the dihydroxy and trihydroxy compounds, but less important for the monohydroxyalkanoic acids. D-Eritadenine ( 1a ) and 3-(adenin-9-yl)-2-hydroxypropanoic acids ( 12a ) are the most potent SAH-hydrolase inhibitors and the only compounds possessing an antiviral activity (against vesicular stomatitis, parainfluenza type 3, reovirus type 1, and vaccinia virus). All these compounds effect a rapid irreversible inactivation of SAH-hydrolase. The esters of 1a and 12a exhibit little, if any inhibitory activity toward the enzyme; they are, however, much more potent antiviral agents than the parent compounds 1a and 12a , most probably acting as prodrugs of the latter. 2-Amino-D-eritadenine, (2 R ,3 R )-5-(adenin-9-yl)-2,3-dihydroxypentanoic acid, 9-(dicarboxymethyl)adenine, 4-(adenin-9-yl)-2-hydroxybutanoic acid, 3-(8-bromoadenin-9-yl)-2-hydroxypropanoic acid and O-carboxymethyl derivatives of 9-(2,3-dihydroxypropyl)- and 9-(2,3,4-trihydroxybutyl)adenine are described as novel compounds.
No abstract is provided for this article.
Facile synthesis of C-4 aryl pyrimidinone nucleoside analogues from an easily prepared O4-arylsulfonate derivative of thymidine is reported. Two O4-arylsulfonylthymidine precursors, (4-methylphenyl)sulfonyl and (2,4,6-trimethylphenyl)sulfonyl, were prepared and analyzed for their stabilities. Of the two, the latter possessed suitable stability as well as reactivity for Pd-catalyzed C-C bond-forming reactions with a variety of arylboronic acids. These reactions at the C-4 position are nontrivial in comparison with similar reactions at the C-5 position of pyrimidine nucleosides, with hydrolysis of the arylsulfonate precursor being a competing reaction in some cases. There are pronounced solvent influences in these reactions, but successful reactions can be attained by careful control of conditions. Many reactions proceeded efficiently at room temperature, and electron-deficient arylboronic acids can also be cross-coupled under suitable conditions. Desilylation of these products was also nontrivial, and various conditions were tested. Finally, antiviral screening was performed with the C-4 aryl pyrimidinone nucleoside analogues, but none possessed any interesting activity. The study represents the first successful synthesis of C-4 aryl pyrimidinone nucleoside analogues by cross-coupling of arylboronic acids with an arylsulfonate derived from a pyrimidine nucleoside, as well as antiviral testing of this new class of compounds.
Human neuroblastoma SK-N-SH cells strongly express CXC-chemokine receptor 4 (CXCR4), the principal coreceptor for X4 HIV-1 strains, and its natural ligand stromal cell-derived factor 1 (SDF-1, recently renamed CXCL12). We investigated the impact of CXCR4 blockade by the specific CXCR4 antagonist AMD3100 or by X4 HIV-1 virus particles on the growth and survival of neuroblastoma SK-N-SH cells. SK-N-SH cell proliferation was inhibited byAMD3100 and anti-CXCL12 neutralizing antibodies, but enhanced by exogenously added CXCL12. Upon prolongedexposure to AMD3100, SK-N-SH cell death occurred throughdeficit of survival-promoting and growth-stimulatory signals generated by endogenous CXCL12. In analogy with the observations made with the CXCR4 inhibitor AMD3100, the X4 HIV-1 strains IIIB and SF-2, but not the R5 strain BaL, caused a marked cytopathic effect and strongly effected SK-N-SH cell death after at least 10 days of incubation. However, no virus production could be detected in the HIV-1-inoculated SK-N-SH cell cultures. Exogenously added CXCL12 afforded partial protection against X4 HIV-1-induced cytopathicity in SK-N-SH cells. Our data indicate that the endogenous CXCL12/CXCR4 signaling axis is critical for neuroblastoma cell survival and proliferation. Long-term blockade of CXCR4 through physical contact with the X4 HIV-1 envelope can cause neuronal cell death. This mechanism may possibly play a role in X4 HIV-associated neurodegeneration.
