Lineage relationship of prostate cancer cell types based on gene expression

Background: Prostate tumor heterogeneity is a major factor in disease management. Heterogeneity could be due to multiple cancer cell types with distinct gene expression. Of clinical importance is the so-called cancer stem cell type. Cell type-specific transcriptomes are used to examine lineage relationship among cancer cell types and their expression similarity to normal cell types including stem/progenitor cells. Methods: Transcriptomes were determined by Affymetrix DNA array analysis for the following cell types. Putative prostate progenitor cell populations were characterized and isolated by expression of the membrane transporter ABCG2. Stem cells were represented by embryonic stem and embryonal carcinoma cells. The cancer cell types were Gleason pattern 3 (glandular histomorphology) and pattern 4 (aglandular) sorted from primary tumors, cultured prostate cancer cell lines originally established from metastatic lesions, xenografts LuCaP 35 (adenocarcinoma phenotype) and LuCaP 49 (neuroendocrine/small cell carcinoma) grown in mice. No detectable gene expression differences were detected among serial passages of the LuCaP xenografts. Results: Based on transcriptomes, the different cancer cell types could be clustered into a luminal-like grouping and a non-luminal-like (also not basal-like) grouping. The non-luminal-like types showed expression more similar to that of stem/progenitor cells than the luminal-like types. However, none showed expression of stem cell genes known to maintain stemness. Conclusions: Non-luminal-like types are all representatives of aggressive disease, and this could be attributed to the similarity in overall gene expression to stem and progenitor cell types.

Comparison of GPX with or without solvent and hand files in removing filling materials from root canals-An ex vivo study

Objective. The aim of this study was to compare GPX instruments and hand files for gutta-percha removal. Study design. Fifty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 5 groups of 10 specimens each, according to the gutta-percha removal techniques: group 1: GPX (21-mm-long teeth); group 2: GPX and xylol as solvent (21-mm-long teeth); group 3: GPX (25-mm-long teeth); group 4: GPX and xylol as solvent (25-mm-long teeth); and group 5: hand files and xylol as solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken, and the teeth were grooved longitudinally and split. The area of residual debris was measured using Sigma Scan software. Results. The time for filling material removal was significantly shorter when GPX was used (P < .05). Overall, hand files and solvent produced fewer remnants of filling materials (P < .05). In the GPX 25 mm-long teeth group, the filling material was not removed in the apical third. Conclusions. Under the experimental conditions, the GPX instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments left a smaller amount of residual filling materials on the canal walls. The GPX instruments did not pull the gutta-percha beyond its tip. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110: 675-680)

Efficacy of Profile .04 taper series 29 in removing filling materials during root canal retreatment-an in vitro study

Objective. The aim of this study was to compare Profile .04 taper series 29 instruments and hand files for gutta-percha removal. Study design. Twenty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 2 groups of 10 specimens each, according to gutta-percha removal techniques: Group 1- Profile series 29 and Group 2- hand files and solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken and the teeth were grooved longitudinally and split. The area of residual debris was measured using computer software. Results. The time for filling material removal was significantly shorter when Profile series 29 was used (P = .00). Regarding cleanliness, there were no statistical differences in the teeth halves evaluations (P = .05). Hand instruments cleaned the canals significantly better than Profiles, in the radiographic analysis considering the whole canal. Overall, the radiographic analysis showed a smaller percentage of residual debris than the teeth halves analysis. Conclusion. The Profile series 29 instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments yielded better root canal cleanliness. Some residual debris was not visualized by radiographs. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: e46-e50)

Effect of blood contamination on the shear bond strength at resin/dentin interface in primary teeth

Purpose: To assess in vitro the shear bond strength at the resin/dentin interface in primary teeth after contamination with fresh human blood. Methods: 75 crowns of primary molars were embedded in acrylic resin and mechanically ground to expose a flat dentin surface. The specimens were randomly assigned to five groups (n=15), according to the surface treatment. Group I (control) had no blood contamination. The other groups were blood-contaminated and subjected to different post-contamination protocols: in Group 2, the surfaces were rinsed with water; in Group 3, the surfaces were air-dried; in Group 4, the surfaces were rinsed and air-dried; and in Group 5, no post-contamination treatment was done. In all groups, a 3-mm dentin bonding site was demarcated, Single Bond adhesive system was applied and resin composite cylinders were bonded. After 24 hours in distilled water, shear bond strength was tested at a crosshead speed of 0.5 mm/minute. Results: Means (in MPa) were: Group 1: 7.1 (+/- 4.2); Group 2: 4.0 (+/- 1.8); Group 3: 0.9 (+/- 0.7); Group 4: 3.9 (+/- 2.2) and Group 5: 1.3 (+/- 1.5). Data were analyzed statistically by the Kruskal-Wallis test at 5% significance level. Groups 2 and 4 were similar to each other (P > 0.05) and both ware similar to Group 1 (P > 0.05). These groups (2, 3 and 4) had statistically significantly higher bond strengths than Groups 3 and 5 (P < 0.05). Blood contamination negatively affected the shear bond strength to primary tooth dentin. Among the blood-contaminated groups, water-rinsed specimens had higher bond strengths than those that were exclusively air-dried or not submitted to any post-contamination protocol before adhesive application.

Engineering of 3D self-directed quantum dot ordering in multilayer InGaAs/GaAs nanostructures by means of flux gas composition

Lateral ordering of InGaAs quantum dots on the GaAs (001) surface has been achieved in earlier reports, resembling an anisotropic pattern. In this work, we present a method of breaking the anisotropy of ordered quantum dots (QDs) by changing the growth environment. We show experimentally that using As(2) molecules instead of As(4) as a background flux is efficient in controlling the diffusion of distant Ga adatoms to make it possible to produce isotropic ordering of InGaAs QDs over GaAs (001). The control of the lateral ordering of QDs under As(2) flux has enabled us to improve their optical properties. Our results are consistent with reported experimental and theoretical data for structure and diffusion on the GaAs surface.