MicroRNA-155 suppresses activation-induced cytidine deaminase-mediated Myc-Igh translocation

MicroRNAs (miRNAs) are small noncoding RNAs that regulate vast networks of genes that share miRNA target sequences. To examine the physiologic effects of an individual miRNA-mRNA interaction in vivo, we generated mice that carry a mutation in the putative microRNA-155 (miR-155) binding site in the 3'-untranslated region of activation-induced cytidine deaminase (AID), designated Aicda(155) mice. AID is required for immunoglobulin gene diversification in B lymphocytes, but it also promotes chromosomal translocations. Aicda(155) caused an increase in steady-state Aicda mRNA and protein amounts by increasing the half-life of the mRNA, resulting in a high degree of Myc-Igh translocations. A similar but more pronounced translocation phenotype was also found in miR-155-deficient mice. Our experiments indicate that miR-155 can act as a tumor suppressor by reducing potentially oncogenic translocations generated by AID.     

Intra-oral bone harvesting: two methods compared using histological and histomorphometric assessments

Aim: This study used morphometric analyses to compare two methods for the intra‐oral harvesting of particulate bone: Mectron Piezosurgery® and the Meta Micross®. Materials and methods: Twenty patients requiring bilateral germectomy of the lower third molars for orthodontic reasons were selected and a sample was harvested from each patient from a standardised donor site (the cortical bone in the area of the retromolar triangle). Ten samples were obtained for each method. The particulate collected were subjected to a histological examination and the samples were analysed considering the following parameters: the mean surface area of fragments, the mean surface area considered vital and the mean surface area considered non‐vital, the mean percentage of area considered vital and the mean percentage of area considered non‐vital, the mean number of normal osteocytes and the mean number of osteocytes with morphological changes identified per unit area (600,000 μm²). The results were analysed, calculating the mean and the corresponding standard deviations, and testing their significance using Student's t‐test, and plotted in graphs. Results: Mectron Piezosurgery® produced significantly larger particles (P<0.05) than the Meta Micross®, with a larger mean surface area considered vital and a significantly larger (P<0.05) surface area considered non‐vital. Mectron Piezosurgery® also produced a smaller mean percentage of area considered vital (64.83%) and a larger mean percentage of area considered non‐vital (35.17%) by comparison with the Meta Micross® (75.34% and 24.66%, respectively). The data also showed that the two methods produce a similar quantity of empty lacunae, and that the Mectron Piezosurgery® produces a larger quantity of osteocytes. Conclusions: The analyses conducted demonstrated that the particulate collected with the Meta Micross® had a smaller mean surface area of the fragments and a smaller surface area of bone considered non‐vital than in the particulate collected using Mectron Piezosurgery®. To cite this article:
Bacci C, Lucchiari N, Valente M, Della Barbera M, Frigo AC, Berengo M. Intra‐oral bone harvesting: two methods compared using histological and histomorphometric assessments. Clin. Oral Impl. Res. 22 , 2011; 600–605.
doi: 10.1111/j.1600‐0501.2010.02022.x     

TOPOFF 2 and the inclusion of dental professionals into federal exercise design and execution

This article examines the dental professional's role in emergency management activities, specifically related to design and execution of such federal exercises as the Top Officials (TOPOFF) series. Experiences from the Chicago TOPOFF 2 exercise are used as an example.     

Youth survival: addressing the role of promoting the acquisition of the prosocial triad and other survival skills in youth

This article addresses the issue of teaching youth skills that will help them to maximize opportunities and positive consequences and minimize exposure to negative consequences in their lives. These skills will allow them to mature into mentally healthy, productive members of society. Essential skills that are critical to allow this maturational process include developing prosocial skills; the ability to recognize, discriminate the level of threat, and use strategies to avoid danger; and the ability to adapt to the changing demands of his or her environment.     

Epithelial-mesenchymal transition induced by the stromal cell-derived factor-1/CXCR4 system in oral squamous cell carcinoma cells

Epithelial-mesenchymal transition (EMT) refers to critical events occasionally observed during tumor progression, including invasion and metastasis, by which cancer cells acquire a fibroblast-like phenotype. Since the stromal cell-derived factor-1 (SDF-1)/CXCR4 system can facilitate lymph node metastasis in oral squamous cell carcinoma (SCC), we have explored the possibility that this system might be involved in EMT. Oral SCC cells, B88 and HNt, which have functional CXCR4 and lymph node metastatic potential, were found to lose their epithelial cell morphology due to SDF-1. In this context, the downregulation of epithelial markers, cytokeratin, E-cadherin and beta-catenin, and the upregulation of mesenchymal marker, vimentin and snail were detected. Furthermore, upregulation of vimentin by treatment with SDF-1 was impaired by phosphatidylinositol 3 kinase (PI3K) inhibitor Wortmannin, but not by mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor U0126. In the type I collagen embedding culture, SDF-1-treated B88 cells formed protruding extensions, but the effect was impaired by treatment with Wortmannin. These results suggested that EMT induced by the SDF-1/CXCR4 system might be involved in the lymph node metastasis of oral SCCs via activation of PI3K-Akt/PKB pathway.