Bisphosphonate inhibits the expression of cyclin A2 at the transcriptional level in normal human oral keratinocytes.

Nitrogen-containing bisphosphonates (N-BPs) are the most widely used anti-resorptive agents in the treatment of bone-related diseases. N-BPs inhibit bone resorption by specifically targeting osteoclasts, bone-resorbing cells. However, soft tissue toxicity, such as oral or gastrointestinal (GI) ulcerations has frequently been reported in N-BP users, suggesting that N-BPs may also directly target cells other than osteoclasts. Previously, we reported that BPs inhibit proliferation without inducing the apoptosis of normal human oral keratinocytes (NHOKs). However, the molecular mechanisms through which N-BPs inhibit the proliferation of NHOKs are not yet fully understood. In this study, we performed gene expression profiling in N-BP-treated NHOKs and identified cyclin A2 as one of the most commonly downregulated genes. When the NHOKs were treated with N-BPs, we found that the level of cyclin A2 was suppressed in a dose- and time-dependent manner. In addition, the protein level of cyclin A2 was also significantly lower in oral epithelial cells in N-BP-treated oral mucosal tissue constructs. Cyclin A2 promoter reporter assay revealed that N-BPs inhibited the luciferase activity, indicating that the inhibition of cyclin A2 expression occurs at the transcriptional level. Furthermore, N-BPs did not alter the expression of cyclin A2 in normal human oral fibroblasts (NHOFs), suggesting that the effect of N-BPs on cyclin A2 expression may be cell-type specific. Thus, the findings of our study demonstrate that the inhibition of NHOK proliferation by N-BPs is mediated, at least in part, by the suppression of cyclin A2 expression at the transcriptional level, which may explain the underlying mechanisms of soft tissue toxicity by N-BPs

20-Year Risks of Breast-Cancer Recurrence after Stopping Endocrine Therapy at 5 Years

The administration of endocrine therapy for 5 years substantially reduces recurrence rates during and after treatment in women with early-stage, estrogen-receptor (ER)-positive breast cancer. Extending such therapy beyond 5 years offers further protection but has additional side effects. Obtaining data on the absolute risk of subsequent distant recurrence if therapy stops at 5 years could help determine whether to extend treatment

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Various conditioning methods for root canals influencing the tensile strength of titanium posts

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, Manufacturers’ instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute_ Aplicap, Flexi-Flow cemTM, Panavia_ 21 EX, Twinlook_) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer’s recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 _C for 24 h and then thermocycled (5000 cycles, 5–55 _C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0Æ5 mm min-1. The data were analysed statistically using ANOVA and corrected with Scheffe´ test due to the significance levels (P < 0Æ05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 % 78 N) followed in descending order by Panavia 21 EX (442 % 97 N), Twinlook (430 % 78 N) and Compolute Aplicap (352 % 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 % 77 N) (P < 0Æ001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 % 102 N) were not significantly different (P < 0Æ05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested

Single Molecule Mechanical Measurement of Inter-Nucleosome Interaction

Histone proteins assemble on DNAs to form arrays of nucleosomes and control the accessibility of the bound regions to transcription machineries. Thus, understanding how the nucleosome wrapping/positioning and the compaction of nucleosome arrays are controlled is the key to understanding epigenetic gene regulation. Each histone protein has unstructured tail region, which are active and multiplexed targets of various types of epigenetic chemical modifications. We still lack understanding of the mechanical control of DNA conformation by the modification of these histone tails. To measure the mechanical properties and dynamics of chromatin fibers modulated by histone tails, we developed single molecule magnetic tweezers combined with single molecule fluorescence imaging. We engineered the tail regions of histone proteins, either by deleting the tail regions or by chemically modifying specific residues, in order to assess their roles in controlling chromatin structure and dynamics. We present preliminary results from the measurement of the chromatin compaction and nucleosome unwrapping dynamics at the single molecule level

Effect of surface treatment of titanium posts on the tensile bond strength

Objectives. Retention of composite resins to metal can be improved when metal surfaces are conditioned. The purpose of this investigation was to investigate the effect of two conditioning treatments on the tensile bond strength of four resin-based luting cements and zinc phosphate cement to titanium posts. Methods. The effect on tensile bond strength of (1) air-particle abrasion (50 pm Al(2)O(3)) and (2) silica coating (30 mu m SiO(x)) and silanization of tapered titanium posts prior to luting with any of the four resin composite luting cements (Compolute Aplicap, Flexi-Flow cemTM, Panavia((R)) 21 EX, TwinLook) were evaluated. The posts luted with zinc phosphate cement (Tenet) were considered as the control group. Following endodontic preparation of 100 intact anterior human teeth with hand instruments, the post spaces were prepared using the opening drills of the corresponding size of the posts. All posts were cemented into the roots according to the manufacturer's instructions of each cement. The specimens were first stored in water at 37 degrees C for 24 h and then subjected to thermocycling (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured on a universal testing machine at a cross-head speed of 0.5 mm/min. Data were analyzed statistically using ANOVA and corrected with Scheffe-test due to the significance levels (P 0.05) were found between the tensile strength of the posts luted with zinc phosphate (414 +/- 102 N) and the resin composite cements. Silica coating and silanization revealed the highest tensile bond strength in posts luted with Compolute((R)) Aplicap but it was not effective for the other experimental groups. Zinc phosphate cement exhibited tensile bond strength as good as resin composite cements. (c) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved

Various conditioning methods for root canals influencing the tensile strength of titanium posts

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, Manufacturers’ instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute_ Aplicap, Flexi-Flow cemTM, Panavia_ 21 EX, Twinlook_) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer’s recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 _C for 24 h and then thermocycled (5000 cycles, 5–55 _C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0Æ5 mm min-1. The data were analysed statistically using ANOVA and corrected with Scheffe´ test due to the significance levels (P < 0Æ05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 % 78 N) followed in descending order by Panavia 21 EX (442 % 97 N), Twinlook (430 % 78 N) and Compolute Aplicap (352 % 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 % 77 N) (P < 0Æ001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 % 102 N) were not significantly different (P < 0Æ05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested

Initial Catalyst−Substrate Association Step in Enyne Metathesis Catalyzed by Grubbs Ruthenium Complex Probed by Time-Dependent Fluorescence Quenching

This communication introduces an FRET-based simple and efficient method for monitoring kinetics and thermodynamics of organic reactions and describes its application to studies on the initial catalyst-substrate association step in the enyne metathesis catalyzed by a Grubbs Ru complex to probe the reaction initiation on the alkyne versus the alkene. The kinetic and thermodynamic parameters of alkene and alkyne with the first generation Grubbs Ru complex, determined by the time-dependent fluorescence quenching of the dye-conjugated substrate by the Ru catalyst, strongly support the dominance of the reaction initiation on alkene over alkyne in the reaction both kinetically and thermodynamically.1122sciescopu