Oocytes segregate chromosomes in the absence of centrosomes. In this situation, the chromosomes direct spindle assembly. It is still unclear in this system which factors are required for homologous chromosome bi-orientation and spindle assembly. The Drosophila kinesin-6 protein Subito, although nonessential for mitotic spindle assembly, is required to organize a bipolar meiotic spindle and chromosome bi-orientation in oocytes. Along with the chromosomal passenger complex (CPC), Subito is an important part of the metaphase I central spindle. In this study we have conducted genetic screens to identify genes that interact with subito or the CPC component Incenp. In addition, the meiotic mutant phenotype for some of the genes identified in these screens were characterized. We show, in part through the use of a heat-shock-inducible system, that the Centralspindlin component RacGAP50C and downstream regulators of cytokinesis Rho1, Sticky, and RhoGEF2 are required for homologous chromosome bi-orientation in metaphase I oocytes. This suggests a novel function for proteins normally involved in mitotic cell division in the regulation of microtubulechromosome interactions. We also show that the kinetochore protein, Polo kinase, is required for maintaining chromosome alignment and spindle organization in metaphase I oocytes. In combination our results support a model where the meiotic central spindle and associated proteins are essential for acentrosomal chromosome segregation. KEYWORDS meiosis; synthetic lethal mutation; homolog bi-orientation; spindle; chromosome segregation; Drosophila C HROMOSOMES are segregated during cell division by the spindle, a bipolar array of microtubules. In somatic cells, spindle assembly is guided by the presence of centrosomes at the poles. In this conventional spindle assembly model, the kinetochores attach to microtubules from opposing centrosomes and tension is established. This satisfies the spindle assembly checkpoint, which then allows the cell to proceed to anaphase (Musacchio and Salmon 2007). Cell division is completed by recruiting proteins to a midzone of antiparallel microtubules that forms between the segregated chromosomes, signaling furrow formation (Fededa and Gerlich 2012;D'Avino et al. 2015). However, spindle morphogenesis in oocytes of many animals occurs in the absence of centrosomes. This may contribute to the high rates of segregation errors that are maternal in origin and are a leading cause of miscarriages, birth defects, and infertility (Herbert et al. 2015). How a robust spindle assembles without guidance from the centrosomes is not well understood. While it is clear that the chromosomes can recruit microtubules and drive spindle assembly (Tseng et al. 2010;Dumont and Desai 2012), how a bipolar spindle is organized and chromosomes make the correct attachments to microtubules is not understood.The Drosophila oocyte provides a genetically tractable system for the identification of genes involved in acentrosomal spindle assembly. Substantial evidence in Drosop...

There is limited information regarding the use of temporary hemiepiphysiodesis for Blount disease. We performed a systematic review of patients treated for Blount disease using either extraperiosteal staples or plates to identify characteristics affecting clinical outcome, including the need for unplanned procedures. A total of 53 patients (63 bone segments) underwent temporary hemiepiphysiodesis at a mean age of 8.8 years (1.8-14.7 years). Overall, 32/63 (51%) segments achieved neutral mechanical axis and 31/63 (49%) underwent unplanned subsequent procedures, with or without a subsequent osteotomy. On the basis of the available heterogeneous data, neither age at index surgery nor the type of implant correlated with the need for unplanned additional surgeries.

No abstract

Introduction:The variability in exposure to various subspecialty rotations during orthopaedic residency across the United States has not been well studied.Methods:Data regarding program size, resident's sex, department leadership, university-based status of the program, outsourcing of subspecialty rotation, and geographic location were collected from websites of 151 US allopathic orthopaedic residency programs. The relationship of these factors with the time allotted for various clinical rotations was analyzed.Results:The number of residents in a program correlated positively with time allocated for elective rotations (r = 0.57, P = 0.0003). Residents in programs where the program director was a general orthopaedic surgeon spent more time on general orthopaedic rotations (22 versus 9.9 months, P = 0.001). Programs where the program director or chairman was an orthopaedic oncologist spent more time on oncology rotations ([3.8 versus 3 months, P = 0.01] and [3.5 versus 2.7 months, P = 0.01], respectively). Residents in community programs spent more time on adult reconstruction than university-based programs (6.6 versus 5.5 months, P = 0.014). Based on multiple linear regression analysis, time allotted for adult reconstruction (t = 2.29, P = 0.02) and elective rotations (t = 2.43, P = 0.017) was positively associated with the number of residents in the program.Conclusions:Substantial variability exists in the time allocated to various clinical rotations during orthopaedic residency. The effect of this variability on clinical competence, trainees' career choices, and quality of patient care needs further study.

In 2013, 1038 applicants, 833 of whom were U.S. graduates, applied for 693 orthopaedic residency spots. Orthopaedic residency program directors thoroughly screen applicant data, selecting those applicants who will be most successful during the residency. Although the most important consideration for program directors is choosing residents who will obtain competence and will pass the orthopaedic board examinations, many applicants are chosen also for their ability to contribute to the field through leadership, research, and teaching.Previous studies have analyzed attitudes of orthopaedic residents toward research and university-based careers 1 . Primary authorship of a publication and past research experience were associated with a greater interest in future research 1 . However, to the best of our knowledge, no study has been done to identify predictors of orthopaedic residents who actually obtain faculty positions in a university-based setting.We hypothesized that predictive factors exist for orthopaedic surgery residents who choose a university-based career. This study looked at both academic and socioeconomic criteria to identify factors that predict residents becoming assistant professors, associate professors, full professors, program directors, or program chairs.