Symbol vs. Digit Substitution Task Performance In Diverse Cultural and Linguistic Groups

In spite of limited empirical data to guide their use, nonverbal neuropsychological measures are frequently utilized in the assessment of non-native English speakers in an effort to minimize cultural and linguistic factors that may influence performance. In this study, three groups of participants from different cultural and linguistic backgrounds were compared on two brief, nonverbal substitution tasks sensitive to cerebral dysfunction: WAIS-R Digit Symbol and the Symbol Digit Modalities Test. Within each group, participants exhibited a similar pattern of performance, earning higher scores on Digit Symbol. However, when dominant Spanish speakers were further subdivided into higher and lower education groups, less educated Spanish speakers achieved lower scores compared to all other groups on both tasks, and failed to show the performance advantage for Digit Symbol. In spite of differences in the respective countries of educational experience, the more highly educated dominant Spanish speakers performed as well as monolingual nonHispanic and Hispanic bilingual participants on both tasks. Years of formal education appears to be the most relevant variable in explaining performance differences across cultural and linguistic groups on these tasks.     

Mineral trioxide aggregate: present and future developments

Portland cement is used in the building industry to make concrete. It is hydraulic and thus it develops its properties well in the presence of moisture. The oral environment is inherently wet, however, all dental materials need a dry field for optimal performance. A mixture of Portland cement and bismuth oxide was developed and marketed as mineral trioxide aggregate (MTA). The first formulation was gray in color followed by a white version and eventually by various similar materials, which are all composed of a tricalcium silicate-based cement and radiopacifier. The MTA was originally suggested for particular clinical uses, such as root-end filling and perforation repair, where maintenance of a dry field is difficult. The suggested uses were extended to apexification and dressing over pulpotomies, pulp capping and also as a sealer cement. The multipurpose use of MTA necessitated the development of improved formulations where material additives were included to the original cement/radiopacifier formulation. These additives supposedly enhance the material's properties and improve its function. Furthermore, the original Portland cement formulation was replaced with tricalcium silicate to avoid the inclusion of an aluminum phase and eliminate the inclusion of trace elements. The bismuth oxide was also replaced with alternative radiopacifiers. The multifaceted use of MTA allows the material to come into contact with different oral environmental conditions, including blood, saliva, tissue fluids, dental restorative materials, tooth structure and even air. These different conditions affect the properties and setting of the material. Future developments should further investigate the material's interactions and strive to create materials which are suited to a specific use.     

Real-time quantitative PCR for assessment of antiviral drug effects against Epstein-Barr virus replication and EBV late mRNA expression

This study assesses the ability of quantitative real-time PCR to measure the effects of virus DNA polymerase inhibitors on EBV DNA and late mRNAs syntheses in EBV-producing cell lines. In-house real-time quantitative PCRs were used to measure EBV DNA (thymidine kinase) and mRNAs (BLLF1 gene/gp350/220, BVRF2 gene/protease) in P3HR-1 and B95-8 cells induced for EBV production by PMA and exposed to ganciclovir, cidofovir and foscarnet. The calculated 50% effective concentrations (EC(50)) for viral DNA replication inhibition in P3HR-1 cells after 7 days of drug exposure were 0.28+/-0.06, 0.29+/-0.01 and 13.6+/-0.17 microg/mL for ganciclovir, cidofovir and foscarnet, respectively. The EC(50) for B95-8 cells were 0.44+/-0.02, 0.70+/-0.06 and 46.8+/-0.5 microg/mL, respectively. The quantitation of the late viral mRNAs showed a decrease of 79-89% in the mRNA amount after 4 days of antiviral treatment. Nevertheless, a substantial amount of mRNA still remained detectable after drug exposure. The real-time PCR is an improvement in the attempt to simplify EBV DNA-quantitation for antiviral assays. The quantitation of late mRNA does not appear as more informative than DNA quantitation for the assessment of the DNA polymerase inhibitor activity, but it may be useful to assess the antiviral activity of drugs acting by another mechanism.     

Rectal peptic ulceration—A rare cause of rectal bleeding

Analysis of the 27 cases of heterotopic gastric mucosa reported in the literature and a new case described here elucidates the main features of this disease: 1) all but one asymptomatic case were diagnosed in infants or in adults under 26 years old; 2) although rectal bleeding occurred in 24 patients, rectal peptic ulceration was found in only 13; 3) six of the patients also had rectal duplication; and 4) 19 times the limited extension of the heterotopic gastric mucosa was compatible with a complete excision by a transanal approach.     

Hydration characteristics of Biodentine and Theracal used as pulp capping materials

Objectives

Investigation of the hydration and characterization of Theracal and Biodentine used for pulp capping.

Methods

The setting mechanism and characterization of set Biodentine and Theracal after immersion in Hank's balanced salt solution (HBSS) for 28 days was investigated by scanning electron microscopy (SEM) of polished specimens and X-ray diffraction (XRD) analysis. The bioactivity and surface microstructure of cements immersed in HBSS or water was also assessed by similar techniques together with leaching in solution investigated by ion chromatography (IC).

Results

Biodentine hydration resulted in the formation of calcium hydroxide which was present in the material matrix and also on the material surface. Theracal was composed of large cement particles which showed some evidence of reaction rims on hydration. The material matrix included a barium zirconate phase as radiopacifier and also a glass phase composed of strontium, silicon and aluminum. This phase could not be detected in XRD analysis. Formation of a calcium phosphate phase was demonstrated on Theracal immersed in HBSS. Both materials leached calcium ions in solution.

Conclusions

The presence of a resin matrix modifies the setting mechanism and calcium ion leaching of Theracal. The clinical implications of these findings need to be investigated.