Postoperative CT scans after resection of brain metastases: neurosurgical routine or added value?

Journal of Neuro-Oncology - Metastasis is the most common brain tumor in adults. It is the standard of care at most North American centers to obtain an early postoperative imaging after their...     

Alterations in mineral composition observed in osteoarthritic joints of cynomolgus monkeys

Osteoarthritis (OA) is a prevalent joint disease that affects more than 40 million Americans and is characterized by degeneration of the articular cartilage and thickening of the underlying subchondral bone. Although subchondral bone thickening has been implicated in articular cartilage degeneration, very little is known about the composition of subchondral bone in OA. In the present study, infrared microspectroscopy (IRMS) was used to determine the chemical composition of the calcified cartilage-subchondral bone plate in a monkey model of OA. Specifically, the levels of mineralization (mineral/protein ratio), carbonate accumulation (carbonate/protein ratio), crystallinity, and collagen structure were determined as a function of animal age and OA severity. OA severity was assessed using a grading scheme that included scores or measurements for several histomorphometric parameters including articular cartilage fibrillation or clefting, subchondral bone thickness, and numbers of tidemarks and chondrocyte clones. Individual scores and measurements were summarized using principal components (factor) analysis. Results demonstrated that the level of mineralization and carbonate content increased as a function of animal age. In addition, bone mineralization level increased as subchondral bone thickness increased. Dramatic increases in the mineralization level and carbonate accumulation were also observed as a function of the number of tidemarks. The presence of multiple tidemarks indicates the occurrence of one or more additional phases of cartilage calcification, suggesting that the observed compositional changes are due to cartilage mineralization. Our results support a reactivation of endochondral ossification that occurs with age, which is more pronounced in OA. No relationships were observed between mineral crystallinity and collagen cross-linking as a function of age or OA severity. In summary, compositional analysis of the mineralized plate beneath the articular cartilage in OA is characterized by thickened, overmineralized calcified cartilage or subchondral bone, which likely puts added mechanical stress on the joint, contributing to the progression of OA.     

Longitudinal study of depressive symptoms and progression of insulin resistance in youth at risk for adult obesity

OBJECTIVE The purpose of this study was to determine whether having childhood depressive symptoms is a risk factor that prospectively predicts impairment in glucose homeostasis. RESEARCH DESIGN AND METHODS A non-treatment-seeking sample of 115 children (aged 5-13 years), oversampled for being at risk for adult obesity, was assessed at baseline and again ~6 years later. Children self-reported depressive symptoms using the Children's Depression Inventory at baseline. Insulin resistance was assessed at baseline and follow-up with the homeostasis model assessment of insulin resistance index (HOMA-IR). RESULTS Children's depressive symptoms were a significant predictor of follow-up HOMA-IR, fasting insulin, and fasting glucose in models accounting for baseline HOMA-IR, insulin, or glucose values; sex; race; baseline age; baseline BMI; change in BMI at follow-up; family history of type 2 diabetes; and time in the study (P < 0.01). CONCLUSIONS In this study, depressive symptomatology at baseline predicted the progression of insulin resistance during child and adolescent development independent of changes in BMI. Research is needed to determine whether early intervention to decrease elevated depressive symptoms in youth ameliorates later development of insulin resistance and lessens the risk of type 2 diabetes.     

A three-dimensional kinematic and kinetic comparison of overground and treadmill walking in healthy elderly subjects

Background

Instrumented treadmills offer a number of advantages for the biomechanical analysis of elderly gait, yet it is unclear how closely treadmill gait approximates overground gait. Although studies have indicated that the kinematics and kinetics of overground and treadmill gait are very similar in young adults, it still needs to be determined whether data collected in elderly adults during treadmill walking can be generalized to overground gait. The purpose of this study, therefore, was to compare the three-dimensional kinematics and kinetics of treadmill gait to overground gait in a group of healthy elderly subjects.

Methods

Three-dimensional kinematic and kinetic data for 18 healthy, nondisabled elderly subjects, age 65–81 years, were collected for speed-matched overground and treadmill walking conditions.

Findings

Overall, the kinematics and kinetics of gait during treadmill and overground walking in the elderly had very similar patterns. However, during treadmill walking elderly subjects showed greater cadence, smaller stride length and stride time as well as reductions in the majority of joint angles, moments and powers when compared to overground walking.

Interpretation

The large increase in cadence suggests that an effective method of acclimation to treadmill walking still needs to be determined. Because of the differences, we believe that in order for instrumented treadmills to become a suitable tool for research and training purposes in healthy elderly, subjects must be adequately acclimated to the treadmill.     

Systemic delivery of human microdystrophin to regenerating mouse dystrophic muscle by muscle progenitor cells

Cell-based therapy for Duchenne muscular dystrophy patients and mdx mice has proven to be a safe but ineffective form of treatment. Recently, a group of cells called muscle side population (SP) cells have been isolated based on their ability to efflux the DNA-binding dye Hoechst. To understand the potential of skeletal muscle SP cells to serve as precursors for muscle, SP cells from the two mice strains mdx(5cv) and C57BL/6N were isolated, transduced, and transplanted. Under coculture conditions with myogenic cells, some cells within the SP cell population can give rise to early Pax7-positive satellite cells and other later stage myogenic cells. Transduced SP cells were transplanted via the tail vein and were shown to successfully deliver enhanced GFP and human microdystrophin to the skeletal muscle of nonirradiated mdx(5cv) mice, thus demonstrating their ability to travel through the capillaries and enter into damaged muscle. These results demonstrate that i.v. delivery of genes via SP cells is possible and that these SP cells are capable of recapitulating the myogenic lineage. Because this approach shows definitive engraftment by using autologous transplantation of noninjured recipients, our data may have substantial implications for therapy of muscular dystrophy.