MRRead-A Novel Approach to Training Residents in Magnetic Resonance Image Temporomandibular Joint Interpretation.

PURPOSE: The purpose of our study was to create an online, web-based training module that would instruct a group of participants in the interpretation of a magnetic resonance image (MRI) of the temporomandibular joint (TMJ) scan in a logical, step-wise manner to locate and identify all relevant features of internal derangement. The investigator's hypothesis was that implementing the MRRead TMJ training module would improve the participants' competency in the interpretation of MRI TMJ scans. METHODS: The investigators designed and implemented a single-group prospective cohort study. The study population was composed of oral and maxillofacial surgery interns, residents, and staff. Subjects eligible for study inclusion were oral and maxillofacial surgeons of any level, between 18 and 50 years of age, that completed the MRRead training module to completion. The primary outcome variable was the difference between the pretest and post-test scores of the participants, and the frequency of missing internal derangement findings before and after the course. Secondary outcomes of interest were subjective data gathered from the course, including participant feedback as well as subjective evaluation of the training module and perceived benefit, as well as the learner's self-reported confidence level in interpreting MRI TMJ scans on their own before and after completion of the course. Descriptive and bivariate statistics were used. RESULTS: The study sample consisted of 68 subjects, aged 20 to 47 (M = 29.1) years. When comparing the results of the exams precourse and post course, the overall frequency of missed features of internal derangement decreased from 19.7 to 5.9, and the total score overall increased from 8.5 to 68.6%. Regarding secondary outcomes, the majority of participants indicated that they agree or strongly agree with a number of positive subjective questions asked. In addition, there was a statistically significant increase in the participants' comfort levels in the interpretation of MRI TMJ scans. CONCLUSION: The results of this study confirm the hypothesis that completing the MRRead training module (www.MRRead.ca) improves competency and comfort among participants in the interpretation of MRI TMJ scans and their identification of features of internal derangement correctly.

CTRead-A Revolutionary Approach to Training Residents in Computed Tomography Facial Bone Interpretation.

PURPOSE: The purpose of our study was to create an online, web-based training module that would instruct a group of residents in the interpretation of a computed tomography (CT) facial bone scan in a logical, stepwise manner to locate and identify all relevant facial fractures. Our hypothesis was that implementing the CTRead facial bones training module would improve residents' competency in the interpretation of CT facial bone scans. MATERIALS AND METHODS: We designed and implemented a prospective quasi-experimental trial. The population for the present study included medical and dental residents. The primary outcome variable was the difference between the pre- and post-test scores of the participants and the frequency of missing fractures before and after the course. The secondary outcomes of interest were subjective data gathered from the course, including participants' feedback and subjective evaluation of the training module and perceived benefit. Another secondary outcome measured was the residents' self-reported confidence level in interpreting the CT facial bone scans on their own before and after completion of the course. Descriptive and bivariate statistics were used. RESULTS: The population sample included 38 residents from North America, aged 25 to 34 years (mean, 28.2 years). When comparing the results from before and after the course, the overall frequency of missed fractures had decreased from 20.7 to 6.4 (P < .001), and the total score overall had increased from 32.7 to 74.7% (P < .001). Regarding the secondary outcomes, most participants indicated that they agreed or strongly agreed with a number of positive subjective queries. In addition, we found a statistically significant increase in the participants' comfort level in the interpretation of CT facial bone scans. CONCLUSIONS: The results of the present study have confirmed the hypothesis that completing the CTRead training module (available at: www.CTRead.ca) improves competency among residents in the interpretation of CT facial bone scans and their correctly identification of facial fractures.

Fin1-PP1 Helps Clear Spindle Assembly Checkpoint Protein Bub1 from Kinetochores in Anaphase.

The spindle assembly checkpoint (SAC) monitors chromosome attachment defects, and the assembly of SAC proteins at kinetochores is essential for its activation, but the SAC disassembly process remains unknown. We found that deletion of a 14-3-3 protein, Bmh1, or hyperactivation of Cdc14 early anaphase release (FEAR) allows premature SAC silencing in budding yeast, which depends on a kinetochore protein Fin1 that forms a complex with protein phosphatase PP1. Previous works suggest that FEAR-dependent Fin1 dephosphorylation promotes Bmh1-Fin1 dissociation, which enables kinetochore recruitment of Fin1-PP1. We found persistent kinetochore association of SAC protein Bub1 in fin1Δ mutants after anaphase entry. Therefore, we revealed a mechanism that clears SAC proteins from kinetochores. After anaphase entry, FEAR activation promotes kinetochore enrichment of Fin1-PP1, resulting in SAC disassembly at kinetochores. This mechanism is required for efficient SAC silencing after SAC is challenged, and untimely Fin1-kinetochore association causes premature SAC silencing and chromosome missegregation.

Coordination of chromatid separation and spindle elongation by antagonistic activities of mitotic and S-phase CDKs.

Because cohesion prevents sister-chromatid separation and spindle elongation, cohesion dissolution may trigger these two events simultaneously. However, the relatively normal spindle elongation kinetics in yeast cohesin mutants indicates an additional mechanism for the temporal control of spindle elongation. Here we show evidence indicating that S-phase CDK (cyclin dependent kinase) negatively regulates spindle elongation. In contrast, mitotic CDK promotes spindle elongation by activating Cdc14 phosphatase, which reverses the protein phosphorylation imposed by S-phase CDK. Our data suggest that S-phase CDK negatively regulates spindle elongation partly through its phosphorylation of a spindle pole body (SPB) protein Spc110. We also show that hyperactive S-phase CDK compromises the microtubule localization of Stu2, a processive microtubule polymerase essential for spindle elongation. Strikingly, we found that hyperactive mitotic CDK induces uncoupled spindle elongation and sister-chromatid separation in securin mutants (pds1Δ), and we speculate that asynchronous chromosome segregation in pds1Δ cells contributes to this phenotype. Therefore, the tight temporal control of spindle elongation and cohesin cleavage assure orchestrated chromosome separation and spindle elongation.

Slk19 clusters kinetochores and facilitates chromosome bipolar attachment.

In all eukaryotic cells, DNA is packaged into multiple chromosomes that are linked to microtubules through a large protein complex called a kinetochore. Previous data show that the kinetochores are clustered together during most of the cell cycle, but the mechanism and the biological significance of kinetochore clustering are unknown. As a kinetochore protein in budding yeast, the role of Slk19 in the stability of the anaphase spindle has been well studied, but its function in chromosome segregation has remained elusive. Here we show that Slk19 is required for kinetochore clustering when yeast cells are treated with the microtubule-depolymerizing agent nocodazole. We further find that slk19Δ mutant cells exhibit delayed kinetochore capture and chromosome bipolar attachment after the disruption of the kinetochore-microtubule interaction by nocodazole, which is likely attributed to defective kinetochore clustering. In addition, we show that Slk19 interacts with itself, suggesting that the dimerization of Slk19 may mediate the interaction between kinetochores for clustering. Therefore Slk19 likely acts as kinetochore glue that clusters kinetochores to facilitate efficient and faithful chromosome segregation.

The multilayer regulation of the metaphase-to-anaphase transition.

The fluctuating activity of the cyclin-dependent kinases (Cdks) is critical for the periodic phosphorylation of a given Cdk substrate. Previous studies have been focus on the positive role of Cdk-dependent protein phosphorylation in cell cycle progression. Recent studies indicate that, in budding yeast, highly active S-phase cyclin-associated Cdk not only promotes DNA synthesis but also inhibits the initiation of chromosome segregation. The FEAR (Cdc14 early anaphase release) pathway alleviates the negative effect of the S-phase cyclin on anaphase by promoting the dephosphorylation of S-phase cyclin-specific substrates, revealing a new layer of regulation in the metaphase-to-anaphase transition.

Pliocene colonization and adaptive radiations in Australia and New Guinea (Sahul): multilocus systematics of the old endemic rodents (Muroidea: Murinae).

The old endemic rodents of Australia and New Guinea (Sahul) represent one or more large adaptive radiations including novel morphological adaptations to aquatic, arboreal, hopping, and arid ecologies. Four tribes recognized among the Sahulian old endemics (Hydromini, Conilurini, Anisomyini, and Uromyini) reflect distinct biogeographic and ecomorphological hypotheses about diversification within the Old Endemics. We present the first character-based phylogeny of the Sahulian Old Endemic rodents with broad sampling, nested within a broader phylogeny of the Murinae. We estimated phylogenies from >2,500 nucleotides of mtDNA sequence and >9,500 nucleotides from six autosomal nuclear loci, for individual genes and for the full concatenated data using parsimony, likelihood, and Bayesian methods. Our results strongly supported monophyly of the group and its sister relationship to the Philippine old endemics of the Chrotomys division. Most striking was the rapid diversification after the Late Miocene or Early Pliocene colonization of New Guinea from the west, consistent with a single colonization of the Sahulian continent. That was followed 2-3 My later by a second adaptive radiation resulting from one or more colonizations of Australia. Monophyly was not supported for the Anisomyini or the Conilurini but was for the Uromyini nested within the Conilurini and for the Hydromyini. Conflict among gene phylogenies was weak, and support for the consensus topology increased with more (even conflicting) data.