Effect Of Sodium Hypochlorite And Peracetic Acid On The Surface Roughness Of Acrylic Resin Polymerized By Heated Water For Short And Long Cycles

Objective: To evaluate the surface roughness of acrylic resin submitted to chemical disinfection via 1% sodium hypochlorite (NaClO) or 1% peracetic acid (C2H4O3). Materials and Methods: The disc-shaped resin specimens (30mm diameter ×4mm height) were polymerized by heated water using two cycles (short cycle: 1h at 74°C and 30min at 100°C; conventional long cycle: 9h at 74°C). The release of substances by these specimens in water solution was also quantified. Specimens were fabricated, divided into four groups (n = 10) depending on the polymerization time and disinfectant. After polishing, the specimens were stored in distilled deionized water. Specimens were immersed in 1% NaClO or 1% C2H4O3 for 30min, and then were immersed in distilled deionized water for 20min. The release of C2H4O3 and NaClO was measured via visual colorimetric analysis. Roughness was measured before and after disinfection. Roughness data were subjected to two-way ANOVA and Tukey's test. Results: There was no interaction between polymerization time and disinfectant in influencing the average surface roughness (Ra, P = 0.957). Considering these factors independently, there were significant differences between short and conventional long cycles (P = 0.012), but no significant difference between the disinfectants hypochlorite and C2H4O3 (P = 0.366). Visual colorimetric analysis did not detect release of substances. Conclusion: It was concluded that there was the difference in surface roughness between short and conventional long cycles, and disinfection at acrylic resins polymerized by heated water using a short cycle modified the properties of roughness.84533537Lai, C.P., Tsai, M.H., Chen, M., Chang, H.S., Tay, H.H., Morphology and properties of denture acrylic resins cured by microwave energy and conventional water bath (2004) Dent Mater, 20, pp. 133-141Austin, A.T., Basker, R.M., Residual monomer levels in denture bases The effects of varying short curing cycles (1982) Br Dent J, 153, pp. 424-426Rahal, J.S., Mesquita, M.F., Henriques, G.E., Nóbilo, M.A., Water sorption and solubility of acrylic resins Influence of chemical and mechanical polishing on water sorption and solubility of denture base acrylic resins (2004) Braz Dent J, 15, pp. 225-230Berger, J.C., Driscoll, C.F., Romberg, E., Luo, Q., Thompson, G., Surface roughness of denture base acrylic resins after processing and after polishing (2006) J Prosthodont, 15, pp. 180-186Kulak-Ozkan, Y., Kazazoglu, E., Arikan, A., Oral hygiene habits, denture cleanliness, presence of yeasts and stomatitis in elderly people (2002) J Oral Rehabil, 29, pp. 300-304Guler, U., Budak, Y., Ruh, E., Ocal, Y., Canay, S., Akyon, Y., Effect of mixing techniques on bacterial attachment and disinfection time of polyether impression material (2013) Eur J Dent, 7, pp. S54-S59Infection control recommendations for the dental office and the dental laboratory (1996) J Am Dent Assoc, 127, pp. 672-680. , Council on Dental Materials, Instrument, and Equipment, Council on Dental Practice, Council on Dental TherapeuticsVerran, J., Maryan, C.J., Retention of Candida albicans on acrylic resin and silicone of different surface topography (1997) J Prosthet Dent, 77, pp. 535-539Mähönen, K., Virtanen, K., Larmas, M., The effect of prosthesis disinfection on salivary microbial levels (1997) J Prosthet Dent, 77, pp. 535-539Elkassas, D.W., Fawzi, E.M., El Zohairy, A., The effect of cavity disinfectants on the micro-shear bond strength of dentin adhesives (2014) Eur J Dent, 8, pp. 184-190Shang, C., Blatchley III, E.R., Chlorination of pure bacterial cultures in aqueous solution (2001) Water Res, 35, pp. 244-254Guiraldo, R.D., Borsato, T.T., Berger, S.B., Lopes, M.B., Gonini-Jr, A., Sinhoreti, M.A., Surface detail reproduction and dimensional accuracy of stone models: Influence of disinfectant solutions and alginate impression materials (2012) Braz Dent J, 23, pp. 417-421Fernandes, F.H., Orsi, I.A., Villabona, C.A., Effects of the peracetic acid and sodium hypochlorite on the colour stability and surface roughness of the denture base acrylic resins polymerised by microwave and water bath methods (2013) Gerodontology, 30, pp. 18-25Chassot, A.L., Poisl, M.I., Samuel, S.M., In vivo and in vitro evaluation of the efficacy of a peracetic acid-based disinfectant for decontamination of acrylic resins (2006) Braz Dent J, 17, pp. 117-121Lottanti, S., Gautschi, H., Sener, B., Zehnder, M., Effects of ethylenediaminetetraacetic, etidronic and peracetic acid irrigation on human root dentine and the smear layer (2009) Int Endod J, 42, pp. 335-343Yap, A.U., Wu, S.S., Chelvan, S., Tan, E.S., Effect of hygiene maintenance procedures on surface roughness of composite restoratives (2005) Oper Dent, 30, pp. 99-104Joniot, S., Salomon, J.P., Dejou, J., Grégoire, G., Use of two surface analyzers to evaluate the surface roughness of four esthetic restorative materials after polishing (2006) Oper Dent, 31, pp. 39-46Barbosa, D.B., de Souza, R.F., Pero, A.C., Marra, J., Compagnoni, M.A., Flexural strength of acrylic resins polymerized by different cycles (2007) J Appl Oral Sci, 15, pp. 424-428Orsi, I.A., Andrade, V.G., Bonato, P.S., Raimundo, L.B., Herzog, D.S., Borie, E., Glutaraldehyde release from heat-polymerized acrylic resins after disinfection and chemical and mechanical polishing (2011) Braz Dent J, 22, pp. 490-496Andrés, M.T., Tejerina, J.M., Fierro, J.F., Reliability of biologic indicators in a mail-return sterilization-monitoring service: A review of 3 years (1995) Quintessence Int, 26, pp. 865-870Koda, T., Tsuchiya, H., Yamauchi, M., Ohtani, S., Takagi, N., Kawano, J., Leachability of denture-base acrylic resins in artificial saliva (1990) Dent Mater, 6, pp. 13-16Angelillo, I.F., Bianco, A., Nobile, C.G., Pavia, M., Evaluation of the efficacy of glutaraldehyde and peroxygen for disinfection of dental instruments (1998) Lett Appl Microbiol, 27, pp. 292-296Orsi, I.A., Andrade, V.G., Effect of chemical disinfectants on the transverse strength of heat-polymerized acrylic resins submitted to mechanical and chemical polishing (2004) J Prosthet Dent, 92, pp. 382-38

Specific Inhibition of MicroRNA Processing Using l‑RNA Aptamers

<i>In vitro</i> selection was used to obtain l-RNA aptamers that bind the distal stem-loop of various precursor microRNAs (pre-miRs). These l-aptamers, termed “aptamiRs”, bind their corresponding pre-miR target through highly specific tertiary interactions rather than Watson–Crick pairing. Formation of a pre-miR–aptamiR complex inhibits Dicer-mediated processing of the pre-miR, which is required to form the mature functional microRNA. One of the aptamiRs, which was selected to bind oncogenic pre-miR-155, inhibits Dicer processing under simulated physiological conditions, with an IC₅₀ of 87 nM. Given that l-RNAs are intrinsically resistant to nuclease degradation, these results suggest that aptamiRs might be pursued as a new class of miR inhibitors

RNA-Catalyzed Cross-Chiral Polymerization of RNA

Biology relies almost exclusively on homochiral building blocks to drive the processes of life. Yet cross-chiral interactions can occur between macromolecules of the opposite handedness, including a previously described polymerase ribozyme that catalyzes the template-directed synthesis of enantio-RNA. The present study sought to optimize and generalize this activity, employing in vitro evolution to select cross-chiral polymerases that use either mono- or trinucleotide substrates that are activated as the 5´-triphosphate. There was only modest improvement of the former activity, but dramatic improvement of the latter, which enables the trinucleotide polymerase to react 10^2–10^3-fold faster than its ancestor and to accept substrates with all possible sequence combinations. The evolved ribozyme can assemble long RNAs from a mixture of trinucleotide building blocks, including a two-fragment form of the ancestral polymerase ribozyme. Further improvement of this activity could enable the generalized cross-chiral replication of RNA, which would establish a new paradigm for the chemical basis of Darwinian evolution

Quantitative and qualitative variables of semen from surubim do Iguaçu, Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae)

Abstract The objective of the present work was to assess the qualitative and quantitative characteristics of semen from the surubim do Iguaçu (Steindachneridion melanodermatum). Induced spermiation was achieved in eleven males with mean weight of 1.76 ± 0.48 kg and average age of two years and semen was collected by stripping. The average volume was 1.34 ± 0.73 mL. The duration of sperm motility was 154.4 ± 72.6 and 149.0 ± 77.5 seconds after activation with hatchery water and distilled water, respectively. The sperm concentration estimated by hemocytometer was 5.423 ± 2.155 x 1010 spermatozoa/mL. The results indicate that S. melanodermatum semen is easily obtained during the spawning season and the seminal characteristics are adequate insemination and subsequent in vitro fertilization