Time-to-contact and multiscale entropy identify differences in postural control in adolescent idiopathic scoliosis

Previous reports on changes in postural control in adolescent idiopathic scoliosis (AIS) compared to healthy controls have been inconsistent. This may suggest center of pressure (COP) sway parameters are not sufficient for determining the ability to maintain quiet upright stance indicating more complex measures may be needed to examine postural control in AIS. The purpose of this investigation was to compare postural control between AIS of different severity levels and healthy controls using time-to-contact (TtC), the complexity index of multiscale entropy (C_r), and COP sway parameters. Thirty-six AIS patients were classified as pre-bracing or pre-operative and compared to 10 healthy control subjects. Overall, the AIS patients showed significantly greater COP sway in mediolateral direction, but deficits with respect to the anteroposterior direction were only systematically identified with the time-to-contact and entropy measures. The multiscale entropy (C_r) results indicate that those with AIS utilize a different control strategy from healthy controls in the mediolateral direction that is more constrained, less complex and less adaptable. AIS severity further reduced this adaptability in the anteroposterior direction. These results indicate it is necessary to examine both planes of motion when investigating postural control in AIS. Additionally, the application of the measures used to assess the nature of the postural control changes in AIS should also be considered.     

Sequence analysis of the protein kinase gene family in human testicular germ-cell tumors of adolescents and adults

The protein kinase gene family is the most frequently mutated in human cancer. Previous work has documented activating mutations in the KIT receptor tyrosine kinase in testicular germ-cell tumors (TGCT). To investigate further the potential role of mutated protein kinases in the development of TGCT and to characterize the prevalence and patterns of point mutations in these tumors, we have sequenced the coding exons and splice junctions of the annotated protein kinase family of 518 genes in a series of seven seminomas and six nonseminomas. Our results show a remarkably low mutation frequency, with only a single somatic point mutation, a K277E mutation in the STK10 gene, being identified in a total of more than 15 megabases of sequence analyzed. Sequencing of STK10 in an additional 40 TGCTs revealed no further mutations. Comparative genomic hybridization and LOH analysis using SNP arrays demonstrated that the 13 TGCTs mutationally screened through the 518 protein kinase genes were uniformly aneuploid with consistent chromosomal gains on 12p, 8q, 7, and X and losses on 13q, 18q, 11q, and 4q. Our results do not provide evidence for a mutated protein kinase implicated in the development of TGCT other than KIT. Moreover, they demonstrate that the general prevalence of point mutations in TGCT is low, in contrast to the high frequency of copy number changes.     

Postoperative gait velocity and mean knee flexion in stance of ambulatory children with spastic diplegia four years or more after multilevel surgery

Factors associated with longer-term outcomes of multilevel orthopaedic surgery in ambulatory children with cerebral palsy using a multivariate approach were evaluated using a retrospective pretest-posttest design. The population included 20 ambulatory children with spastic diplegia who had undergone multilevel orthopaedic surgery with a minimum of 4-year interval between a preoperative and a postoperative gait assessment. Multiple regression analysis was used to identify factors associated with postoperative velocity and mean knee flexion in stance. Independent variables included in the regression models were velocity, mean knee flexion in stance, age at preoperative evaluation, Gross Motor Function Classification System level, use of ankle-foot orthoses, leg length, age-adjusted body mass index, number of surgical procedures, and range of motion of hip and knee. Children who demonstrated faster postoperative gait velocity 4 years or more after surgery were younger at the time of initial evaluation, had undergone fewer surgical procedures, had faster preoperative gait velocity, used ankle-foot orthoses postoperatively, and had increased hip extension range of motion postoperatively (R = 0.55). Children who demonstrated greater knee flexion in stance 4 years or more after surgery had undergone more surgical procedures, greater postoperative popliteal angle, and less knee extension range of motion (R = 0.73). This study demonstrates the usefulness of a multivariate approach toward understanding and predicting outcomes. The results of this study will provide clinicians and researchers more information about those factors associated with maintained improvements in the longer term and may be useful for treatment planning.