Biophysical foundations underlying TMS: Setting the stage for an effective use of neurostimulation in the cognitive neurosciences

Transcranial Magnetic Stimulation (TMS) induces electrical currents in the brain to stimulate neural tissue. This article reviews our present understanding of TMS methodology, focusing on its biophysical foundations. We concentrate on how the laws of electromagnetic induction apply to TMS; addressing issues such as the location, area (i.e., focality), depth, and mechanism of TMS. We also present a review of the present limitations and future potential of the technique.     

Use of a geographic information system to track smelter-related lead exposures in children: North Lake Macquarie, Australia, 1991–2002

Background  

To determine patterns of childhood lead exposure in a community living near a lead and zinc smelter in North Lake Macquarie, Australia between 1991 and 2002.     

A Method for Determining Skeletal Lengths from DXA Images

Background  

Skeletal ratios and bone lengths are widely used in anthropology and forensic pathology and hip axis length is a useful predictor of fracture. The aim of this study was to show that skeletal ratios, such as length of femur to height, could be accurately measured from a DXA (dual energy X-ray absorptiometry) image.     

Relaxin down-regulates renal fibroblast function and promotes matrix remodelling in vitro.

BACKGROUND: Renal fibroblasts are important effector cells in tubulointerstitial fibrosis, with experimental antifibrotic strategies focusing on the functional down-regulation of these cells. Several experimental models of fibrosis have provided evidence for the effectiveness of the polypeptide hormone relaxin as a potential antifibrotic agent. This study was conducted to further elucidate the antifibrotic mechanisms of relaxin on renal fibroblasts in vitro. METHODS: Rat cortical fibroblasts were obtained from outgrowth culture of renal tissue isolated from kidneys 3 days post-unilateral ureteric obstruction and constituted 100% of cells studied. A relaxin radio-receptor assay was used to establish binding of relaxin to renal fibroblasts in vitro. Functional studies then examined the effects of H2 relaxin (0, 1, 10 and 100 ng/ml) on fibroblast kinetics, expression of alpha-smooth muscle actin (alpha-SMA), total collagen synthesis, collagenase production and collagen-I lattice contraction. CTGF mRNA expression was also measured by northern analysis. RESULTS: H2 relaxin bound with high affinity to rat renal fibroblasts, but receptor numbers were low. Consistent with its previously reported bimodal effect, transforming growth factor (TGF-beta 1) reduced fibroblast proliferation, an effect abrogated by H2 relaxin. Fibroblasts exposed to H2 relaxin (100 ng/ml) for 24 h demonstrated decreased immunostaining for alpha-SMA and reduced alpha-SMA protein expression compared with controls. There was a trend for a relaxin-mediated reduction in total collagen synthesis and alpha 1(I) mRNA expression with large dose-related increases in collagenase protein expression being observed. TGF-beta 1-stimulated collagen-I lattice contraction was significantly inhibited following co-incubation with 100 ng/ml relaxin. Incremental doses of H2 relaxin had no significant effect on CTGF mRNA expression. CONCLUSIONS: The findings of this study suggest that the antifibrotic effects of relaxin involve down-regulation of fibroblast activity, increase in collagenase synthesis and restructuring of collagen-I lattices, which are consistent with its known physiological role of matrix remodelling. Although there appears to be an interaction between TGF-beta 1 and H2 relaxin, this does not appear to involve a reduction in CTGF mRNA expression.     

Giant dermoid associated with foot duplication

After resection at birth of an accessory left foot, a white male infant was followed up for a slowly enlarging posterior calf mass of the same leg. When the patient was 8 years old, the mass was thought to have enlarged sufficiently to warrant excisional biopsy. Histologic examination of the tumor was consistent with the diagnosis of a dermoid cyst, revealing a lesion lined with stratified squamous epithelium and containing cutaneous adnexal structures represented by eccrine sweat glands. A congenital dermoid in the extremities is unusual. The prognosis following removal is good, and recurrence is rare.     

The Usefulness of Magnetic Resonance Imaging in the Diagnosis of Anterolateral Impingement of the Ankle

The purpose of this study is to assess the sensitivity and specificity of magnetic resonance imaging (MRI) in the diagnosis of anterolateral impingement of the ankle and to assess the most helpful sequence in making the diagnosis. Twenty-four patients who had undergone ankle arthroscopy were chosen. Twelve patients had arthroscopically documented anterolateral impingement, and 12 patients with no impingement on arthroscopy served as controls. Two musculoskeletal radiologists and an orthopedic surgeon, blinded to the operative diagnosis, retrospectively reviewed selective MRI images in the sagittal, axial, and coronal planes. The sensitivities and specificities were calculated for all 3 reviewers. The Kendall coefficient of concordance was calculated for overall agreement among reviewers. Sensitivities varied from 0.75 to 0.83, whereas specificities varied from 0.75 to 1.00. Using the Fisher exact test of contingency, the sensitivities and specificities showed that all reviewers' interpretations were statistically significant with P = .039, .001, and .012, respectively. The axial images were felt to be most helpful in making the diagnosis. The physicians felt that the sagittal images were helpful in 67%, 83%, and 100%, respectively. MRI is a useful tool that can aid the clinician in the diagnosis of anterolateral impingement of the ankle. T1 sagittal images demonstrating displacement of the normal fat signal anterior to the fibula by scar can be useful and help to confirm the diagnosis.