HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs.

Several proteins and RNAs expressed by mammalian viruses have been reported to interfere with RNA interference (RNAi) activity. We investigated the ability of the HIV-1-encoded RNA elements Trans-Activation Response (TAR) and Rev-Response Element (RRE) to alter RNAi. MicroRNA let7-based assays showed that RRE is a potent suppressor of RNAi activity, while TAR displayed moderate RNAi suppression. We demonstrate that RRE binds to TAR-RNA Binding Protein (TRBP), an essential component of the RNA Induced Silencing Complex (RISC). The binding of TAR and RRE to TRBP displaces small interfering (si)RNAs from binding to TRBP. Several stem-deleted RRE mutants lost their ability to suppress RNAi activity, which correlated with a reduced ability to compete with siRNA-TRBP binding. A lentiviral vector expressing TAR and RRE restricted RNAi, but RNAi was restored when Rev or GagPol were coexpressed. Adenoviruses are restricted by RNAi and encode their own suppressors of RNAi, the Virus-Associated (VA) RNA elements. RRE enhanced the replication of wild-type and VA-deficient adenovirus. Our work describes RRE as a novel suppressor of RNAi that acts by competing with siRNAs rather than by disrupting the RISC. This function is masked in lentiviral vectors co-expressed with viral proteins and thus will not affect their use in gene therapy. The potent RNAi suppressive effects of RRE identified in this study could be used to enhance the expression of RNAi restricted viruses used in oncolysis such as adenoviruses.

Effects of a peripheral enamel margin on the long-term bond strength and nanoleakage of composite/dentin interfaces produced by self-adhesive and conventional resin cements.

PURPOSE: This study evaluated the effects of peripheral enamel margins on the long-term bond strength (µTBS) and nanoleakage in resin/dentin interfaces produced by self-adhesive and conventional resin cements. MATERIALS AND METHODS: Five self-adhesive [RelyX-Unicem (UN), RelyX-U100 (UC), GCem (GC), Maxcem (MC), Set (SET)] and 2 conventional resin cements [RelyX-ARC(RX), Panavia F(PF)] were used. An additional group included the use of a two-step self-etching adhesive (SE Bond) with Panavia F (PS). One hundred ninety-two molars were assigned to 8 groups according to luting material. Five-mm-thick composite disks were cemented and assigned to 3 subgroups according to water-exposure condition (n = 6): 24-h peripheral exposure (24h-PE-enamel margins), or 1 year of peripheral (1 yr-PE) or direct exposure (1 yr-DE-dentin margin). Restored teeth were sectioned into beams and tested in tension at 1 mm/min. Data were analyzed by two-way ANOVA and Tukey's test. Two additional specimens in each group were prepared for nanoleakage evaluation. Nanoleakage patterns were observed under SEM/TEM. RESULTS: Except for RX, no significant reduction in µTBS was observed between 24h-PE and 1 yr-PE. 1 yr-DE reduced µTBS for RX, PF, GC, MC, and SET. No significant reduction in µTBS was observed for PS, UC, and UN after 1 year. After 1 yr-DE, RX and PS presented the highest µTBS, and SET and MC the lowest. Nanoleakage was reduced when there was a peripheral enamel margin. SET and MC presented more silver deposition than other groups. CONCLUSION: The presence of a peripheral enamel margin reduced the degradation rate in resin/dentin interfaces for most materials. The µTBS values produced by the multi-step luting agents RX and PS were significantly higher than those observed for self-adhesive cement.

Value of a breast imaging unit in the detection of breast cancer in Mexico.

The screening breast cancer detection rate in Mexico is low. The main objective of this study was to determine the breast cancer detection rate in a Mexican population that attended a breast imaging unit, in which the same radiologist comprehensively evaluated and interpreted breast imaging studies. A total of 5,429 mammograms performed between 2015 and 2016 were evaluated. Rates for biopsy indication, biopsies performed and positive biopsies for cancer were determined. The malignancy detection rate, after a comprehensive imaging evaluation in a breast imaging unit, was 24.3 per 1,000 mammograms. In symptomatic women was 52.9 per 1,000 mammograms, and in screening women was 11.1 per 1,000 mammograms. Breast imaging units in which a comprehensive imaging approach is performed represent an opportunity for low- and middle-income countries without population-based screening programs to achieve a more efficient detection of breast cancer, without generating a higher cost.

Characterization of the TRBP domain required for dicer interaction and function in RNA interference.

BACKGROUND: Dicer, Ago2 and TRBP are the minimum components of the human RNA-induced silencing complex (RISC). While Dicer and Ago2 are RNases, TRBP is the double-stranded RNA binding protein (dsRBP) that loads small interfering RNA into the RISC. TRBP binds directly to Dicer through its C-terminal domain. RESULTS: We show that the TRBP binding site in Dicer is a 165 amino acid (aa) region located between the ATPase and the helicase domains. The binding site in TRBP is a 69 aa domain, called C4, located at the C-terminal end of TRBP. The TRBP1 and TRBP2 isoforms, but not TRBPs lacking the C4 site (TRBPsDeltaC4), co-immunoprecipitated with Dicer. The C4 domain is therefore necessary to bind Dicer, irrespective of the presence of RNA. Immunofluorescence shows that while full-length TRBPs colocalize with Dicer, TRBPsDeltaC4 do not. tarbp2-/- cells, which do not express TRBP, do not support RNA interference (RNAi) mediated by short hairpin or micro RNAs against EGFP. Both TRBPs, but not TRBPsDeltaC4, were able to rescue RNAi function. In human cells with low RNAi activity, addition of TRBP1 or 2, but not TRBPsDeltaC4, rescued RNAi function. CONCLUSION: The mapping of the interaction sites between TRBP and Dicer show unique domains that are required for their binding. Since TRBPsDeltaC4 do not interact or colocalize with Dicer, we suggest that TRBP and Dicer, both dsRBPs, do not interact through bound dsRNA. TRBPs, but not TRBPsDeltaC4, rescue RNAi activity in RNAi-compromised cells, indicating that the binding of Dicer to TRBP is critical for RNAi function.

Microtensile bond strength of new self-adhesive luting agents and conventional multistep systems.

STATEMENT OF PROBLEM: Several self-adhesive luting agents have recently been introduced on the market. It is crucial to know the effectiveness of such luting agents prior to their clinical application. PURPOSE: The purpose of this study was to evaluate the microtensile bond strengths (microTBS) produced by different self-adhesive cements and compare them with conventional luting agents. MATERIAL AND METHODS: Six self-adhesive cements (RelyX Unicem (UN), RelyX U100 (UC), SmartCem 2 (SC), G-Cem (GC), Maxcem (MC), and SeT (SET), and 2 conventional luting agents, one that uses a 2-step etch-and-rinse adhesive (RelyX ARC (RX)), and one that uses a 1-step self-etching adhesive (Panavia F (PF)), were used in this study. An additional group included the use of a 2-step self-etching primer adhesive system (Clearfil SE Bond) prior to the application of Panavia F (PS). Fifty-four human molars were abraded to expose occlusal surfaces and were assigned to 9 groups according to the luting material (n=6). Five composite resin (Filtek Z250) discs (12 mm in diameter, 5 mm thick) were cemented on the teeth according to manufacturers' instructions. After 24 hours of water storage, restored teeth were serially sectioned into beams with a cross-sectional area of approximately 1 mm2 at the bonded interface and were tested in tension with a crosshead speed of 1 mm/min. Failure mode was determined using scanning electron microscopy. Data were statistically analyzed by 1-way ANOVA and Tukey's studentized range HSD test (alpha =.05). RESULTS: Mean bond strengths (SD) in MPa were: RX, 69.6 (16.6)A; PS, 49.2 (9.7)A; PF, 33.7 (13.9)AB; GC, 16.9 (10.3)BC; UC, 15.3 (3.4)BC; UN, 12.5 (2.4)C; MC 11.5 (6.8)CD; SC, 8.5 (4.9)CD; SET, 4.6 (0.5)D. Groups with different uppercase letters were significantly different from each other (P<.05). The predominant failure mode of the self-adhesive cements was adhesive between the resin cement and dentin. CONCLUSIONS: The bond strengths produced by the multistep luting agents were significantly higher than those observed for most self-adhesive cements.

Proteomic fingerprinting in HIV/HCV co-infection reveals serum biomarkers for the diagnosis of fibrosis staging.

BACKGROUND: Hepatic complications of hepatitis C virus (HCV), including fibrosis and cirrhosis are accelerated in human immunodeficiency virus (HIV)-infected individuals. Although, liver biopsy remains the gold standard for staging HCV-associated liver disease, this test can result in serious complications and is subject to sampling errors. These challenges have prompted a search for non-invasive methods for liver fibrosis staging. To this end, we compared serum proteome profiles at different stages of fibrosis in HIV/HCV co- and HCV mono-infected patients using surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS). METHODS: Sera from 83 HIV/HCV co- and 68 HCV mono-infected subjects in 4 stages of fibrosis were tested. Sera were fractionated, randomly applied to protein chip arrays (IMAC, CM10 and H50) and spectra were generated at low and high laser intensities. RESULTS: Sixteen biomarkers achieved a p value < 0.01 (ROC values > 0.75 or < 0.25) predictive of fibrosis status in co-infected individuals and 14 in mono infected subjects. Five of these candidate biomarkers contributed to both mono- and co-infected subjects. Candidate diagnostic algorithms were created to distinguish between non-fibrotic and fibrotic individuals using a panel of 4 biomarker peaks. CONCLUSION: These data suggest that SELDI MS profiling can identify diagnostic serum biomarkers for fibrosis that are both common and distinct in HIV/HCV co-infected and HCV mono-infected individuals.

Esthetic rehabilitation of anterior conoid teeth: comprehensive approach for improved and predictable results.

The esthetic success of a dental treatment depends on the correct diagnosis, treatment plan and clinical and laboratory procedures. This clinical report describes a diagnostically based protocol for conservative preparations on anterior teeth for adhesively retained composite and porcelain restorations. The diagnostic additive wax-up, periodontal esthetic crown-lengthening, direct acrylic mock-up, conservative preparations for ceramic laminate veneers, luting procedures, direct restorations with composite resin used for the esthetic rehabilitation of a patient presenting conoid lateral incisors, and an unsatisfactory class IV restoration in the left central incisor are presented. An accurate diagnostic and interdisciplinary approach is necessary for obtaining improved, conservative and predictable esthetic results in esthetically compromised areas, such as the anterior maxillary dentition.

TRBP control of PACT-induced phosphorylation of protein kinase R is reversed by stress.

The TAR RNA binding Protein, TRBP, inhibits the activity of the interferon-induced protein kinase R (PKR), whereas the PKR activator, PACT, activates its function. TRBP and PACT also bind to each other through their double-stranded RNA binding domains (dsRBDs) and their Medipal domains, which may influence their activity on PKR. In a human immunodeficiency virus (HIV) long terminal repeat-luciferase assay, PACT unexpectedly reversed PKR-mediated inhibition of gene expression. In a translation inhibition assay in HeLa cells, PACT lacking the 13 C-terminal amino acids (PACTDelta13), but not full-length PACT, activated PKR and enhanced interferon-mediated repression. In contrast, in the astrocytic U251MG cells that express low TRBP levels, both proteins activate PKR, but PACTDelta13 is stronger. Immunoprecipitation assays and yeast two-hybrid assays show that TRBP and PACTDelta13 interact very weakly due to a loss of binding in the Medipal domain. PACT-induced PKR phosphorylation was restored in Tarbp2(-/-) murine tail fibroblasts and in HEK293T or HeLa cells when TRBP expression was reduced by RNA interference. In HEK293T and HeLa cells, arsenite, peroxide, and serum starvation-mediated stresses dissociated the TRBP-PACT interaction and increased PACT-induced PKR activation, demonstrating the relevance of this control in a physiological context. Our results demonstrate that in cells, TRBP controls PACT activation of PKR, an activity that is reversed by stress.

Alternativas quirúrgicas en el tratamiento de la neurocisticercosis / Alternative surgical in the treatment of the neurocysticercosis

La neurocisticercosis ha sido por muchos años una preocupación importante para los neurocirujanos de los países en desarrollo, particularmente de Asia, Africa y América Latina, existiendo una profusa literatura en estas áreas geográficas. La cirugía ha sido siempre considerada como tratamiento sintomático de esta enfermedad parasitaria, sin embargo los más importantes aportes se han dado recién en las dos útimas décadas y así hemos mejorado mucho en el diagnóstico con la aparición de la TAC al final de los años 70 y la RMN al final de los 80; por esta época también fueron introducidas las pruebas de Elisa y Western Blot, técnicas para el diagnóstico inmunológico de gran sensibilidad, que siguen siendo extraordinariamente útiles. Durante las cuatro décadas anteriores, operamos 237 pacientes con neurocisticercosis y realizamos 494 tipos de procedimientos quirúrgicos distintos. Dada la facilidad de diagnóstico (Elisa, Western Blot, CAT y RNM) entre 1994 y 2003 tuvimos solamente 52 casos. Muchos casos fueron tratados por neurólogos o médicos generales. La forma racemosa de cisticercosis estuvo presente en casi la mitad del número total. La hipertensión intracranial fue la forma más común de presentación clínica y por ello 43 de 52 casos requirieron una derivación del LCR y 27 de 43 derivaciones fueron requeridas como único procedimiento quirúrgico posible. Craneotomía fue requerida sólo en 10 casos y 12 casos fueron tratados con neuroendoscopía. confirmamos que la neuroendoscopía es una técnica útil en el tratamiento de la cisticercosis ventricular, con extirpación de quistes y membranas en 9 casos. Fenestración de III Ventrículo fue ralizada en 5 casos. En 3 casos fue necesario también fenestración de septum pellucidum. Dado que la localización ventricular de la cisticercosis es muy frecuente (27 casos) recomendamos la exploración intraventricular con el uso de técnicas neuroendoscópicas.

La iniciación de la educación médica en Santafé y en el Nuevo Reino de Granada / The origins of medical education in Santafe and in the Nuevo Reino de Granada

El comienzo de la enseñnza médica en el Nuevo Reino de Granada tuvo lugar en la naciente Santafé, bajo los auspicios de la comunidad jesuíta. La conferencia inicial se llevó a cabo el primero de Abril de 1636, en el Colegio Seminario de San Bartolomé. El conferencista fué Rodrigo Enríquez de Andrade, médico español, graduado en la Universidad de Alcalá de Henares, quien hizo su exposición en latín ante una numeroso concurrencia. Este ciclo de enseñanza duró poco tiempo y fue siguido por otros intentos durante la colonia y los comienzos de la República. Estos esfuerzos culminaron con la fundación de la Universidad Nacional 1867. En nuestro continente, dos escuelas de Medicina habían comenzado labores con anterioridad : la Pontificia y Real Universidad de México (1578) y la Universidad de San Marcos en Lima (1635). Por el contrario, la primera escuela de Medicina en comenzar tareas en los Estados Unidos fue el Colegio de Filadelfia (1795)

La iniciación de la educación médica en Santafé y en el Nuevo Reino de Granada

El comienzo de la enseñnza médica en el Nuevo Reino de Granada tuvo lugar en la naciente Santafé, bajo los auspicios de la comunidad jesuíta. La conferencia inicial se llevó a cabo el primero de Abril de 1636, en el Colegio Seminario de San Bartolomé. El conferencista fué Rodrigo Enríquez de Andrade, médico español, graduado en la Universidad de Alcalá de Henares, quien hizo su exposición en latín ante una numeroso concurrencia. Este ciclo de enseñanza duró poco tiempo y fue siguido por otros intentos durante la colonia y los comienzos de la República. Estos esfuerzos culminaron con la fundación de la Universidad Nacional 1867. En nuestro continente, dos escuelas de Medicina habían comenzado labores con anterioridad : la Pontificia y Real Universidad de México (1578) y la Universidad de San Marcos en Lima (1635). Por el contrario, la primera escuela de Medicina en comenzar tareas en los Estados Unidos fue el Colegio de Filadelfia (1795).