Further improvements on the factors affecting bone mineral density measured by quantitative micro-computed tomography

The effects of imaging parameters and special configuration of objects within the reconstruction space on the micro computed tomography (μCT) based mineral density have been explored, and a series of density correction curves have been presented. A manufacturer-provided calibration phantom (0, 100, 200, 400, 800 mg HA/cm(3)) was imaged at all possible imaging conditions (n=216) based on energy, resolution, vial diameter, beam hardening correction factor and averaging. For each imaging condition, a linear regression model was fitted to the observed versus expected densities, and the intercepts (β(0)) and slopes (β(1)) of the regression lines and each density level were modeled using multiple regression modeling. Additionally, a custom made phantom (0, 50, 150, 500, 800, 1000 and 1500 mg HA/cm(3)) was scanned in order to study the effects of location and orientation of an object within the reconstruction space and presence of surrounding objects on μCT based mineral density. The energy, vial diameter and beam hardening correction factor were significant predictors of cumineral density (P values<0.001), while averaging and resolution did not have a significant effect on the observed density values (P values>0.1) except for 0.0 density (P values<0.04). Varying the location of an object within the reconstruction space from the center to the periphery resulted in a drop in observed mineral density up to 10% (P values<0.005). The presence of surrounding densities resulted in decreased observed mineral density up to 17% at the center and up to 14% at the periphery of the reconstruction space (P values<0.001 for all densities). Changing the orientation of the sample also had a significant effect on the observed mineral density, resulting in up to 16% lower observed mineral density for vertical vs. horizontal orientation at the center of the reconstruction space (P value<0.001). We conclude that energy, resolution and post processing correction factor are significant predictors of the observed mineral density in μCT.     

The relationship between preoperative cervical alignment and postoperative spinal cord drift after decompressive laminectomy and arthrodesis for cervical spondylotic myelopathy

BackgroundCervical spondylotic myelopathy represents a debilitating disorder, often resulting in significant neurological impairment over time. Cervical laminectomy has enjoyed a successful track record in the surgical management of these patients. Little is understood regarding the significance of postdecompressive migration of the spinal cord in relation to patient outcome.MethodsPreoperative and postoperative cervical spine MRIs of 28 patients who underwent cervical laminectomy and fusion for the treatment of CSM were reviewed. Radiographic parameters including preoperative cervical alignment, LDI, space available at the level cepahlad/caudad to the decompression, percent spinal cord expansion at the radiographically most compressed level, and spinal cord drift to the midpoint of the spinal cord were measured and subsequently analyzed for statistical correlation. The recovery rate based on the mJOA score was calculated for each patient and analyzed for correlation with spinal cord drift.ResultsThe Cobb angle C2-7, cervical spinal angle, and CCI represented tightly correlated measures of cervical alignment. The preoperative cervical alignment did not statistically correlate with postoperative spinal cord drift. No statistical correlation was revealed between postdecompressive spinal cord drift and recovery rate.ConclusionsPreoperative cervical alignment does not statistically correlate with postoperative spinal cord drift in patients undergoing multisegmental decompressive laminectomy and fusion for CSM. The observation of significant posterior shifting of the spinal cord in the context of straight or kyphotic preoperative alignment suggests that posterior decompression and arthrodesis represent a viable option in the surgical management of patients with CSM with nonlordotic preoperative alignment.     

Speaking under pressure: Low linguistic complexity is linked to high physiological and emotional stress reactivity

What can a speech reveal about someone's state? We tested the idea that greater stress reactivity would relate to lower linguistic cognitive complexity while speaking. In Study 1, we tested whether heart rate and emotional stress reactivity to a stressful discussion would relate to lower linguistic complexity. In Studies 2 and 3, we tested whether a greater cortisol response to a standardized stressful task including a speech (Trier Social Stress Test) would be linked to speaking with less linguistic complexity during the task. We found evidence that measures of stress responsivity (emotional and physiological) and chronic stress are tied to variability in the cognitive complexity of speech. Taken together, these results provide evidence that our individual experiences of stress or “stress signatures”—how our body and mind react to stress both in the moment and over the longer term—are linked to how complex our speech under stress.     

Anti-angiogenic effects of resveratrol mediated by decreased VEGF and increased TSP1 expression in melanoma-endothelial cell co-culture

Resveratrol, a naturally occurring polyphenol, has been reported to be an anti-tumor and chemopreventive agent. Recent data show that it may also exert anti-angiogenic effects. We hypothesized that the anti-angiogenic activity of resveratrol may be caused by modulation of tumor cell release of thrombospondin-1 (TSP1) and vascular endothelial growth factor (VEGF) into the extracellular matrix, leading to vascular endothelial cell (VEC) apoptosis. We therefore evaluated the effects of resveratrol on melanoma cell lines co-cultured with vascular endothelial cells in monolayer and in three dimensional spheroids. We found that resveratrol stimulated isolated VEC proliferation, while it caused growth inhibition of VECs grown with melanoma cells in three-dimensional co-culture. This effect was associated with increased melanoma cell expression of tumor suppressor protein 53 and matrix protein TSP1, as well as decreased hypoxia-driven expression of hypoxia inducible factor-1α and inhibition of VEGF production.