RESUMO
RNA ligands that bind to the human immunodeficiency virus type-1 (HIV-1) gag polyprotein with 10(-9) M affinity were isolated from a complex pool of RNAs using an in vitro selection method. The ligands bind to two different regions within gag, either to the matrix protein or to the nucleocapsid protein. Binding of a matrix ligand to gag did not interfere with the binding of a nucleocapsid ligand, and binding of a nucleocapsid ligand to gag did not interfere with the binding of a matrix ligand. However, binding of a nucleocapsid ligand to gag did interfere with binding of an RNA containing the HIV-1 RNA packaging element (psi), even though the sequence of the nucleocapsid ligand is not similar topsi. The minimal sequences required for the ligands to bind to matrix or nucleocapsid were determined. Minimal nucleocapsid ligands are predicted to form a stem-loop structure that has a self-complementary sequence at one end. Minimal matrix ligands are predicted to form a different stem-loop structure that has a CAARU loop sequence. The properties of these RNA ligands may provide tools for studying RNA interactions with matrix and nucleocapsid, and a novel method for inhibiting HIV replication.
Assuntos
Proteínas do Capsídeo , Produtos do Gene gag/metabolismo , HIV-1/metabolismo , Proteínas do Nucleocapsídeo , Proteínas/metabolismo , RNA/metabolismo , Proteínas Virais , Sequência de Bases , Sítios de Ligação , Ligação Competitiva , Capsídeo/genética , Capsídeo/metabolismo , Produtos do Gene gag/genética , HIV-1/genética , Humanos , Ligantes , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Nucleocapsídeo/metabolismo , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismo , Proteínas/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Relação Estrutura-Atividade , Produtos do Gene gag do Vírus da Imunodeficiência HumanaRESUMO
Although crossover femorofemoral grafts have had good long-term patency, all patients have not been symptomatically improved. Seventy-one patients underwent 80 femorofemoral bypasses from 1968 to 1978. Hemodynamic assessment included preoperative and postoperative segmental Doppler pressures and femoral artery waveform recordings. Preoperative and selective postoperative arteriography was routinely performed. Twenty-nine failures occurred predominantely in two groups, those with greater than 50% stenosis of the donor iliac artery and those with severe recipient limb outflow occlusive disease. Ten patients with normal outflow beds bilaterally associated with 10% to 50% stenosis of the donor iliac artery underwent successful femorofemoral reconstruction. Progression of donor iliac artery disease was seen in only two patients. Cumulative five-year patency was 74%. Operative mortality totaled three (3.8%). This study supports the use of femorofemoral bypass as a primary procedure when proper guidelines are used.