The prototype HIV-1 maturation inhibitor, bevirimat, binds to the CA-SP1 cleavage site in immature Gag particles

<p>Abstract</p> <p>Background</p> <p>Bevirimat, the prototype Human Immunodeficiency Virus type 1 (HIV-1) maturation inhibitor, is highly potent in cell culture and efficacious in HIV-1 infected patients. In contrast to inhibitors that target the active site of the viral protease, bevirimat specifically inhibits a single cleavage event, the final processing step for the Gag precursor where p25 (CA-SP1) is cleaved to p24 (CA) and SP1.</p> <p>Results</p> <p>In this study, photoaffinity analogs of bevirimat and mass spectrometry were employed to map the binding site of bevirimat to Gag within immature virus-like particles. Bevirimat analogs were found to crosslink to sequences overlapping, or proximal to, the CA-SP1 cleavage site, consistent with previous biochemical data on the effect of bevirimat on Gag processing and with genetic data from resistance mutations, in a region predicted by NMR and mutational studies to have α-helical character. Unexpectedly, a second region of interaction was found within the Major Homology Region (MHR). Extensive prior genetic evidence suggests that the MHR is critical for virus assembly.</p> <p>Conclusions</p> <p>This is the first demonstration of a direct interaction between the maturation inhibitor, bevirimat, and its target, Gag. Information gained from this study sheds light on the mechanisms by which the virus develops resistance to this class of drug and may aid in the design of next-generation maturation inhibitors.</p

Potent Activity of the HIV-1 Maturation Inhibitor Bevirimat in SCID-hu Thy/Liv Mice

The HIV-1 maturation inhibitor, 3-O-(3',3'-dimethylsuccinyl) betulinic acid (bevirimat, PA-457) is a promising drug candidate with 10 nM in vitro antiviral activity against multiple wild-type (WT) and drug-resistant HIV-1 isolates. Bevirimat has a novel mechanism of action, specifically inhibiting cleavage of spacer peptide 1 (SP1) from the C-terminus of capsid which results in defective core condensation.Oral administration of bevirimat to HIV-1-infected SCID-hu Thy/Liv mice reduced viral RNA by >2 log(10) and protected immature and mature T cells from virus-mediated depletion. This activity was observed at plasma concentrations that are achievable in humans after oral dosing, and bevirimat was active up to 3 days after inoculation with both WT HIV-1 and an AZT-resistant HIV-1 clinical isolate. Consistent with its mechanism of action, bevirimat caused a dose-dependent inhibition of capsid-SP1 cleavage in HIV-1-infected human thymocytes obtained from these mice. HIV-1 NL4-3 with an alanine-to-valine substitution at the N-terminus of SP1 (SP1/A1V), which is resistant to bevirimat in vitro, was also resistant to bevirimat treatment in the mice, and SP1/AIV had replication and thymocyte kinetics similar to that of WT NL4-3 with no evidence of fitness impairment in in vivo competition assays. Interestingly, protease inhibitor-resistant HIV-1 with impaired capsid-SP1 cleavage was hypersensitive to bevirimat in vitro with a 50% inhibitory concentration 140 times lower than for WT HIV-1.These results support further clinical development of this first-in-class maturation inhibitor and confirm the usefulness of the SCID-hu Thy/Liv model for evaluation of in vivo antiretroviral efficacy, drug resistance, and viral fitness

The Performance of Primary Dual-Mobility Total Hip Arthroplasty in Patients Aged 55 Years and Younger: A Systematic Review

Background: Dual-mobility (DM) total hip arthroplasty (THA) combines the stabilization advantage provided by large head articulation with the low friction advantage provided by small head articulation. There is momentum for DM to be used in a wider selection of patients, with some advocating for DM to be the routine primary total hip construct. Further investigation is needed to determine whether the use of DM in younger adults is validated by aggregate data. Our objective was to review the literature for the clinical performance of DM THA in patients aged 55 years and younger. Methods: A systematic review of the literature was performed according to the guidelines of Preferred Reporting in Systematic Reviews and Meta-Analyses. Inclusion in the review required clinical outcome reporting for DM primary THA in ambulatory patients aged 55 years or younger. The risk of bias was appraised using the Cochrane risk of bias in nonrandomized studies of interventions and the quality of the evidence was appraised using the Grading of Recommendations Assessment, Development and Evaluation framework. Results: Across a sample of 1048 cases, the frequency weighted term of follow-up was 87.7 months. The pooled rate of revision was 9.5%. The Harris Hip Score significantly improved from 49.1 preoperatively to 93 postoperatively. The Postel-Merle d'Aubigné score significantly improved from 10.5 preoperatively to 17.1 postoperatively. Conclusions: The literature demonstrates satisfactory short-term outcomes with a mitigated risk of dislocation for DM used as primary THA in patients aged 55 years and younger. The current findings suggest that third-generation designs provide reduced rates of intraprosthetic dislocation and improved survivorship

Characterization of viral particles isolated from primary cultures of human breast cancer cells

The association of human breast cancer with sequences similar to the mouse mammary tumor virus (MMTV) has been shown, but convincing evidence for the presence of viral particles in breast tumors has been lacking. We have described the complete proviral structure of a retrovirus in human breast cancer. This provirus, designated as human mammary tumor virus (HMTV), was 95% homologous to MMTV and revealed features of a replication-competent virus. We have therefore investigated the production of viral particles in primary cultures of human breast cancer (MSSM). Cells isolated from ascites or pleural effusions of patients with metastatic breast cancer contained viral sequences in their DNA, expressed Env protein, and showed retroviral particles by electron microscopy. Viral particles from culture media exhibited morphologic features of β-retroviruses sedimenting at buoyant densities of 1.12 to 1.18 g/mL in sucrose gradients and showed reverse transcriptase activity. cDNA sequences from virion RNA were synthesized, amplified, and sequenced and all the virion genes were detected and 70% of the virion RNA was sequenced. The sequence homologies were, respectively, 85% to 95% compared with the MMTV and HMTV proviruses we have previously described. These results clearly show that breast cancer cells in primary cultures produced HMTV viral particles that are similar to the mouse virus and which may play a role in human breast cancer pathogenesis. ©2007 American Association for Cancer Research.Fil: Melana, Stella M.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Nepomnaschy, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Oklahoma Health Sciences Center; Estados UnidosFil: Sakalian, Michael. University of Oklahoma Health Sciences Center; Estados UnidosFil: Abbott, Andrea. University of Oklahoma Health Sciences Center; Estados UnidosFil: Hasa, Jennifer. University of Oklahoma Health Sciences Center; Estados UnidosFil: Holland, James F.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Pogo, Beatriz G.T.. University of Oklahoma Health Sciences Center; Estados Unido

Characterization of viral particles isolated from primary cultures of human breast cancer cells

The association of human breast cancer with sequences similar to the mouse mammary tumor virus (MMTV) has been shown, but convincing evidence for the presence of viral particles in breast tumors has been lacking. We have described the complete proviral structure of a retrovirus in human breast cancer. This provirus, designated as human mammary tumor virus (HMTV), was 95% homologous to MMTV and revealed features of a replication-competent virus. We have therefore investigated the production of viral particles in primary cultures of human breast cancer (MSSM). Cells isolated from ascites or pleural effusions of patients with metastatic breast cancer contained viral sequences in their DNA, expressed Env protein, and showed retroviral particles by electron microscopy. Viral particles from culture media exhibited morphologic features of β-retroviruses sedimenting at buoyant densities of 1.12 to 1.18 g/mL in sucrose gradients and showed reverse transcriptase activity. cDNA sequences from virion RNA were synthesized, amplified, and sequenced and all the virion genes were detected and 70% of the virion RNA was sequenced. The sequence homologies were, respectively, 85% to 95% compared with the MMTV and HMTV proviruses we have previously described. These results clearly show that breast cancer cells in primary cultures produced HMTV viral particles that are similar to the mouse virus and which may play a role in human breast cancer pathogenesis. ©2007 American Association for Cancer Research.Fil: Melana, Stella M.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Nepomnaschy, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Oklahoma Health Sciences Center; Estados UnidosFil: Sakalian, Michael. University of Oklahoma Health Sciences Center; Estados UnidosFil: Abbott, Andrea. University of Oklahoma Health Sciences Center; Estados UnidosFil: Hasa, Jennifer. University of Oklahoma Health Sciences Center; Estados UnidosFil: Holland, James F.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Pogo, Beatriz G.T.. University of Oklahoma Health Sciences Center; Estados Unido

Control de calidad de diferentes silicatos de calcio mediante distintos análisis de viabilidad celular

OBJETIVO: Los silicatos de calcio son biomateriales utilizados para realizar protección pulpar directa y sellado de perforaciones, por lo que es fundamental conocer en profundidad su biocompatibilidad de dos silicatos de calcio sobre fibroblastos gingivales humanos, mediante la utilización de distintos análisis de viabilidad celular. MÉTODO: Se utilizaron fibroblastos gingivales humanos que fueron cultivados en placa de 24 pocillos en una concentración de células/500 µl de medio de cultivo DMEM. Posteriormente las células fueron expuestas, durante 72 horas, a discos de diámetro y de espesor de dos biomateriales, uno a base silicato tricálcico purificado (Biodentine, Septodont, Francia) y otro a base de silicato de calcio modificado con resina (TheraCal LC, Bisco, USA). Para analizar las posibles alteraciones morfológicas, se realizó microscopía óptica; para evaluar la proliferación celular se utilizó la técnica de WST-1 y para el análisis de permeabilidad de membrana plasmática un ensayo de Live (Invitrogen, USA). Los fibroblastos cultivados en medio DMEM (CM) se usaron como control positivo de biocompatibilidad y los fibroblastos incubados en 2.0% tritón X (CT) como controles negativos. Para el análisis estadístico se utilizó Mann Whitney.Fil: Rodríguez, M. A. Universidad Nacional de Córdoba; Argentina.Fil: Ximenes Olivera, Ana Celeste. Universidad Federal de Minas Gerais. Laboratorio de Biomateriales; Brasil.Fil: Rodríguez, Ismael Ángel. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Histología y Embriología B; Argentina.Fil: Gómez de Ferraris, María Elsa. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Histología y Embriología B; Argentina.Fil: Sakalian, María Candela. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Endodoncia A; Argentina.Biotecnología relacionada con la Salu