An in vitro CT Comparison of Gutta-Percha Removal with Two Rotary Systems and Hedstrom Files.

Introduction: To evaluate the efficacy of NiTi mechanical rotary instrumentation and Hedstrom file for gutta-percha/sealer removal computed tomography (CT) was utilized in vitro.

Materials And Methods: Thirty extracted human single rooted teeth, each with a single canal were selected. The samples were decoronated with a double faced diamond disk to have 17-mm root; teeth roots were instrumented with K-files up to master apical file #30 using step back technique.

Protein phosphatase 5 is required for ATR-mediated checkpoint activation.

In response to DNA damage or replication stress, the protein kinase ATR is activated and subsequently transduces genotoxic signals to cell cycle control and DNA repair machinery through phosphorylation of a number of downstream substrates. Very little is known about the molecular mechanism by which ATR is activated in response to genotoxic insults. In this report, we demonstrate that protein phosphatase 5 (PP5) is required for the ATR-mediated checkpoint activation.

Requirement of protein phosphatase 5 in DNA-damage-induced ATM activation.

The checkpoint kinase ATM is centrally involved in the cellular response to DNA double-strand breaks. However, the mechanism of ATM activation during genotoxic stress is only partially understood. Here we report a direct regulatory linkage between the protein serine-threonine phosphatase 5 (PP5) and ATM.