Cytogenetic and molecular analysis of MLL rearrangements in acute lymphoblastic leukaemia survivors

The successful treatment of paediatric malignancies by multimodal therapy has improved outcomes for children with cancer, especially those with acute lymphoblastic leukaemia (ALL). Second malignant neoplasms, however, represent a serious complication after treatment. Depending on dosage, 2-12% of patients treated with topoisomerase II inhibitors and/or alkylating agents develop treatment-related acute myeloid leukaemia characterized by translocations at 11q23. Our goal was to study MLL rearrangements in peripheral lymphocytes using cytogenetic and molecular methods in order to evaluate the late effects of cancer therapy in patients previously treated for childhood ALL. Chromosomal rearrangements at 11q23 were analysed in cytogenetic preparations from 49 long-term ALL survivors and 49 control individuals. Patients were subdivided depending on the inclusion or omission of topoisomerase II inhibitors (VP-16 and/or VM-26) in their treatment protocol. The statistical analysis showed significant (P = 0.007) differences between the frequency of translocations observed for the groups of patients and controls. These differences were also significant (P = 0.006) when the groups of patients (independent of the inclusion of topoisomerase II inhibitors) and controls were compared (P = 0.006). The frequencies of extra signals, however, did not differ between groups of patients and controls. Several MLL translocations were detected and identified by inverse polymerase chain reaction, followed by cloning and sequencing. Thirty-five patients (81%) presented putative translocations; among those, 91% corresponded with t(4;11) (q21;q23), while the other 9% corresponded with t(11;X), t(8;11)(q23;q23) and t(11;16). Our results indicate an increase in MLL aberrations in childhood ALL survivors years after completion of therapy. The higher frequency in this cohort might be associated with therapy using anti-tumoural drugs, independent of the inclusion of topoisomerase II inhibitors. Even though the biological significance of these rearrangements needs further investigation, they demonstrate a degree of genome instability, indicating the relevance of cytogenetic and molecular studies during the follow-up of patients in complete clinical remission.

Physical Properties and Interfacial Adaptation of Three Epoxy Resin-based Sealers

Introduction: The aim of the study was to evaluate the radiopacity, solubility, flow, film thickness, setting time, and adaptation to the root canal walls of 3 epoxy resin based sealers: AH Plus, Acroseal, and Adseal. Methods: Physical tests were performed following American National Standards Institute/American Dental Association`s requirements. For interfacial adaptation analysis, 30 maxillary canines were shaped by using Pro Taper instruments. The specimens were divided into 3 groups (n = 10): group 1, AH Plus; group 2, Acroseal; and group 3, Adseal. The sealers were mixed with rhodamine B dye, and the canals were filled by using the lateral compaction technique. The percentage of gaps and voids area was calculated at 2, 4, and 6 mm levels from the apex. Statistical evaluation was performed by using analysis of variance for physical analysis and nonparametric Kruskal-Wallis and Dunn tests for interfacial adaptation (P<.05). Results: No statistical differences were found for adaptation, percentage of voids, solubility, flow, and film thickness among the sealers (P>.05). AH Plus was significantly more radiopaque (P<.05). For the setting time, there were statistical differences among all the studied sealers (P<.05). Conclusions: AH Plus, Acroseal, and Adseal presented similar root canal adaptation, solubility, flow, and film thickness. Statistical differences were found for radiopacity and setting time (P<.05). (J Endod 2011;37:1417-1421)

The efficacy of a highly concentrated fluoride dentifrice on bovine enamel subjected to erosion and abrasion

Background. Researchers have proposed the use of fluoride for the prevention of enamel wear; however, only limited information is available about the impact of fluoridated dentifrices. Because tooth wear is a well-recognized dental problem, the authors conducted an in situ, ex vivo study to assess the efficacy of a highly concentrated fluoride dentifrice on bovine enamel subjected to erosion and abrasion. Methods. The authors conducted a double-blind, crossover in situ study consisting of three phases (seven days each). In each phase, the authors tested one of the dentifrices (5,000 parts per million fluoride [F]; 1,100 ppm F; no F). They performed erosive challenges with the use of cola drink (60 seconds, four times per day) and abrasive challenges via toothbrushing (30 seconds, four times per day). The authors determined the enamel loss via profilometry. Results. The authors tested the data by using two-way analysis of variance (P <.05). For the erosion-plus-abrasion condition, the study results showed that enamel wear was significantly higher than that with erosion alone. The findings showed no significant differences between the dentifrices regarding enamel wear. Conclusions. Within the in situ, ex vivo conditions of this study, the authors concluded that the highly concentrated fluoride dentifrice did not have a protective effect on enamel against erosion and erosion plus toothbrushing abrasion. Clinical Implications. Patients at risk of developing enamel erosion should benefit from preventive measures other than fluoride dentifrice, because even a highly concentrated fluoride dentifrice does not appear to prevent enamel erosion.

Human osteoblastic cell response to a Ca- and P-enriched titanium surface obtained by anodization

The aim of the present study was to evaluate the in vitro osteogenic potential of subcultured human osteoblastic cells derived from alveolar bone on a titanium (Ti) surface produced by an anodized alkali treatment (BSP-AK). Primary osteoblastic cells were subcultured on BSP-AK and machined Ti discs (control) and grown for periods of up to 21 days under osteogenic conditions. Morphologic and biochemical methods were used to assess important parameters of in vitro bone-like tissue formation. Although no major differences were observed between the BSP-AK and the control Ti surface in terms of cell attachment and mineralized matrix formation, a significant increase in cell population, ALP activity, and collagen content was detected in cultures on BSP-AK surface. Our results demonstrate that human osteoblastic cells are sensitive to the BSP-AK-modified Ti surface during the transitional stage between the end of the proliferative phase and the onset of the differentiation /matrix maturation ones. Together with the good mechanical properties exhibited by the Ca- and P- coating, our findings suggest that BSP-AK treatment could be useful for the development of a new surface for dental and orthopedic implants. (c) 2008 Wiley Periodicals, Inc.J Biomed Mater Res 88A: 841-848, 2009