RESUMO
The HIV-1 regulatory protein Tat and the accessory protein Vpr are thought to stimulate viral replication and contribute to viral pathogenesis as extracellular proteins. Humoral immune responses to these early viral proteins may therefore be beneficial. We examined serum anti-Tat and anti-Vpr IgG by ELISA in the GRIV cohort of HIV-1 seropositive slow/non-progressors (NP) and fast-progressors (FP), and in seronegative controls. Based on information obtained during a brief follow-up period (median = 20 months), NPs were sub-grouped as those maintaining non-progression status and therefore stable (NP-S), and those showing signs of disease progression (NP-P). As the primary comparison, initial serum anti-Tat and anti-Vpr IgG (prior to follow-up) were analyzed in the NP sub-groups and in FPs. Anti-Tat IgG was significantly higher in stable NP-S compared to unstable NP-P (P = 0.047) and FPs (P < 0.0005); the predictive value of higher anti-Tat IgG for maintenance of non-progression status was 92% (P = 0.029). In contrast, no-difference was observed in anti-Vpr IgG between NP-S and NP-P, although both were significantly higher than FPs (P = 0.001). Serum anti-Tat IgG mapped to linear epitopes within the amino-terminus, the basic domain and the carboxy-terminal region of Tat in stable NP-S. Similar epitopes were identified in patients immunized with the Tat-toxoid in a Phase I study in Milan. High titer serum anti-Tat IgG from both GRIV and Milan cohorts cross-reacted in ELISA with Tat from diverse viral isolates, including HIV-1 subtype-E (CMU08) and SIVmac251 Tat; a correlation was observed between anti-Tat IgG titers and cross-reactivity. These results demonstrate that higher levels of serum anti-Tat IgG, but not anti-Vpr IgG, are associated with maintenance of non-progression status in HIV-1 infection. Evidence that vaccination with the Tat toxoid induces humoral immune responses to Tat similar to those observed in stable non-progressors is encouraging for vaccine strategies targeting Tat.
Assuntos
Produtos do Gene tat/imunologia , Produtos do Gene vpr/imunologia , Anticorpos Anti-HIV/sangue , HIV-1/imunologia , Estudos de Coortes , Reações Cruzadas/imunologia , Ensaio de Imunoadsorção Enzimática/métodos , Seguimentos , Sobreviventes de Longo Prazo ao HIV , Soropositividade para HIV/imunologia , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Mapeamento de Peptídeos/métodos , Produtos do Gene tat do Vírus da Imunodeficiência Humana , Produtos do Gene vpr do Vírus da Imunodeficiência HumanaRESUMO
STATEMENT OF PROBLEM: Many different materials and methods have been used to fabricate or repair veneer facings with composites, but only a few of these have been studied. PURPOSE: This study compared the tensile bond strengths of composites to a gold-palladium alloy with the use of several surface treatment methods. MATERIAL AND METHODS: Forty alloy specimens were cast in Eclipse (52% gold and 37.5% palladium) in the form of truncated cones. These specimens were divided equally into 4 groups. In group I, the bonding surfaces of the metal cones were treated with Silicoater MD. Truncated cones of Dentacolor composite were bonded to the metal surfaces and light-polymerized. In group II, the bonding surfaces of the metal cones were air-particle abraded with 50 microm aluminum oxide and coated with C&B Metabond. Truncated cones of Epic-TMPT composite were bonded to the metal surfaces and light-polymerized. In group III, the bonding surfaces of the metal cones were air-particle abraded with CoJet-Sand. Truncated cones of Pertac-Hybrid composite were bonded to the metal surfaces and light-polymerized. In group IV, the bonding surfaces of the metal cones were air-particle abraded with CoJet-Sand. Truncated cones of Visio-Gem were bonded to the metal surfaces and light-polymerized. After 24 hours of water immersion at 37 degrees C and 1000 thermal cycles in water at 5 degrees C and 55 degrees C, tensile forces were applied to all specimens with a universal testing machine. Analysis of variance was applied to the data (P<.05), and differences among means were determined with a Tukey-Kramer interval of 5.4 MPa. RESULTS: Tensile bond strengths in MPa were as follows: Dentacolor, 14 +/- 5; Epic-TMPT, 12 +/- 4; Pertac-Hybrid, 13 +/- 5; and Visio-Gem, 18 +/- 4. The tensile bond strength of Visio-Gem was significantly higher than that of Epic-TMPT, but no differences were found among Dentacolor, Pertac-Hybrid, and Epic-TMPT (P<.05). CONCLUSION: Within the limitations of this study, all 4 bonding systems tested produced high bond strengths between composites and a gold-palladium alloy after thermal cycling.