Effect of wrist position on distal radioulnar joint stability: A biomechanical study

We investigated distal radioulnar joint (DRUJ) stability in different wrist positions and examined the relative contribution of each ligamentous component of the triangular fibrocartilage complex (TFCC) to DRUJ stability. We used nine fresh‐frozen cadavers. The humerus and ulna were fixed at 90° elbow flexion. The radiocarpal unit was translated relative to the ulna in dorsopalmar directions with the wrist in five positions. Displacement of the unit was measured by an electromagnetic tracking device. Magnitudes of displacement were compared between different wrist positions in various sectioning stages: ulnocarpal ligament (UCL) sectioning, radioulnar ligaments (RUL) sectioning, and extensor carpi ulnaris (ECU) floor sectioning. Wrist position and sectioning stage significantly influenced the displacement. In intact wrists, the displacement in wrist extension was significantly lower than that in neutral. However, after UCL sectioning, there were no longer any significant differences. After RUL sectioning, the displacement in radial deviation was significantly lower than that in neutral. Following ECU floor sectioning, there were no longer any significant differences. Thus, in intact wrists, DRUJ stability in wrist extension is likely due to tightening of the UCL. After complete RUL sectioning, DRUJ is stabilized in radial deviation due to tightening of the ECU floor. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1247–1251, 2014.     

Renal distribution of collagen type IV α chains in autosomal-dominant Alport syndrome

Background Autosomal-dominant Alport syndrome is a recognized, but relatively uncommon, form of Alport syndrome. Recently, mutations in theCOL4A3 andCOL4A4 genes, which encode collagen type IV α3 and α4 chains, respectively, have been shown to cause the disease. However, the distribution of α(IV) chains has yet to be determined. Methods To clarify the renal distribution of α(IV) chains, immunohistochemistry of α1(IV) to α6(IV) chains was performed, using chain-specific monoclonal antibodies, raised by us, and an antigen retrieval procedure. Paraffin-embedded renal sections, obtained from 8 patients from 3 families with the disease, were examined. Results The distribution of all 6 α(IV) chains was not significantly different between the 8 patients and the controls. Collagen type IV α1 and α2 chains were ubiquitously expressed, while α3 to α6 chains were detected in the basement membranes of the glomerulus and Bowman's capsule, and/or part of the tubular basement membranes. Conclusions Our findings contrast with those of X-linked and autosomal-recessive Alport syndrome. The distribution pattern of α(IV) chains may provide a useful means of distinguishing the different forms of Alport syndrome.     

Abnormal asymmetry of white matter integrity in schizophrenia revealed by voxelwise diffusion tensor imaging

A number of magnetic resonance imaging (MRI) studies have revealed morphological cortical asymmetry in the normal human brain, and reduction or inversion of such hemispheric asymmetry has been reported in schizophrenia. On the other hand, diffusion tensor imaging (DTI) studies have reported inconsistent findings concerning abnormal asymmetry of white matter integrity in schizophrenia. Our aim was to confirm whether there is reduced or inverted asymmetry of white matter integrity in the whole brain in schizophrenia. For this study, 26 right-handed schizophrenia patients, and 32 matched healthy control subjects were investigated. Voxelwise analysis of DTI data was performed using the tract-based spatial statistics. The fractional anisotropy (FA) images were normalized and projected onto the symmetrical white matter skeleton, and the laterality index (LI) of FA, determined by 2 × (left - right)/(left + right), was calculated. The results reveal that schizophrenia patients and healthy controls showed similar patterns of overall FA asymmetries. In the group comparison, patients showed significant reduction of LI in the external capsule (EC), and posterior limb of the internal capsule (PLIC). The EC cluster revealed increased rightward asymmetry, and the PLIC cluster showed reduced leftward asymmetry. Rightward-shift of FA in the EC cluster correlated with negative symptom severity. Considering that the EC cluster includes the uncinate and inferior occipitofrontal fasciculi, which have connections to the orbitofrontal cortex, abnormal asymmetry of white matter integrity in schizophrenia may play a crucial role in the pathogenesis of schizophrenia, through the altered connectivity to the orbitofrontal cortex.     

Cerebral blood flow in the ventromedial prefrontal cortex correlates with treatment response to low-frequency right prefrontal repetitive transcranial magnetic stimulation in the treatment of depression

Aims: Low‐frequency right prefrontal repetitive transcranial magnetic stimulation (rTMS) is effective in treating depression, and its antidepressant effects have proven to correlate with decreases in cerebral blood flow (CBF) in the orbitofrontal cortex and subgenual cingulate cortex. However, a predictor of treatment response to low‐frequency right prefrontal rTMS in depression has not been identified yet. The aim of this study was to estimate regional CBF in the frontal regions and investigate the correlation with treatment response to low‐frequency right prefrontal rTMS in depression. Methods: We examined 26 depressed patients for the correlation between treatment response to rTMS and regional CBF in the frontal regions, by analyzing their brain scans with ^99mTc‐ethyl cysteinate dimer before rTMS treatment. CBF in 16 brain regions was estimated using fully automated region of interest analysis software. Two principal components were extracted from CBF in 16 brain regions by factor analysis with maximum likelihood method and Promax rotation with Kaiser normalization. Results: Sixteen brain regions were divided into two groups: dorsolateral prefrontal cortex (superior frontal, medial frontal, middle frontal, and inferior frontal regions) and ventromedial prefrontal cortex (anterior cingulate, subcallosal, orbital, and rectal regions). Treatment response to rTMS was not correlated with CBF in the dorsolateral prefrontal cortex, but it was correlated with CBF in the ventromedial prefrontal cortex. Conclusion: These findings suggest that CBF in the ventromedial prefrontal cortex may be a potential predictor of low‐frequency right prefrontal rTMS, and depressed patients with increased CBF in the ventromedial prefrontal cortex may show a better response.     

Auditory gamma oscillations predict global symptomatic outcome in the early stages of psychosis: A longitudinal investigation

Objectives

The gamma-band auditory steady-state response (ASSR) is thought to reflect the function of parvalbumin-positive γ-aminobutyric acid (GABA)-ergic interneurons and may be a candidate biomarker in early psychosis. Although previous cross-sectional studies have shown that gamma-band ASSR is reduced in early psychosis, whether reduced gamma-band ASSR could be a predictor of the long-term prognosis remains unknown.