Somatosensory-motor cortex interactions measured using dual-site transcranial magnetic stimulation

BackgroundDual-site transcranial magnetic stimulation (ds-TMS) is a neurophysiological technique to measure functional connectivity between cortical areas.Objective/HypothesisTo date, no study has used ds-TMS to investigate short intra-hemispheric interactions between the somatosensory areas and primary motor cortex (M1).MethodsWe examined somatosensory-M1 interactions in the left hemisphere in six experiments using ds-TMS. In Experiment 1 (n = 16), the effects of different conditioning stimulus (CS) intensities on somatosensory-M1 interactions were measured with 1 and 2.5 ms inter-stimulus intervals (ISIs). In Experiment 2 (n = 16), the time-course of somatosensoy-M1 interactions was studied using supra-threshold CS intensity at 6 different ISIs. In Experiment 3 (n = 16), the time-course of short-interval cortical inhibition (SICI) and effects of different CS intensities on SICI were measured similar to Experiments 1 and 2. Experiment 4 (n = 13) examined the effects of active contraction on SICI and somatosensory-M1 inhibition. Experiments 5 and 6 (n = 10) examined the interactions between SAI with either 1 ms SICI or somatosensory-M1 inhibition.ResultsExperiments 1 and 2 revealed reduced MEP amplitudes when applying somatosensory CS 1 ms prior to M1 TS with 140 and 160% CS intensities. Experiment 3 demonstrated that SICI at 1 and 2.5 ms did not correlate with somatosensory-M1 inhibition. Experiment 4 found that SICI but not somatosensory-M1 inhibition was abolished with active contraction. The results of Experiments 5–6 showed SAI was disinhibited in presence of somatosensory-M1 while SAI was increased in presence of SICI.ConclusionCollectively, the results support the notion that the somatosensory areas inhibit the ipsilateral M1 at very short latencies.     

Ricinus communis Intoxications in Human and Veterinary Medicine-A Summary of Real Cases

Accidental and intended Ricinus communis intoxications in humans and animals have been known for centuries but the causative agent remained elusive until 1888 when Stillmark attributed the toxicity to the lectin ricin. Ricinus communis is grown worldwide on an industrial scale for the production of castor oil. As by-product in castor oil production ricin is mass produced above 1 million tons per year. On the basis of its availability, toxicity, ease of preparation and the current lack of medical countermeasures, ricin has gained attention as potential biological warfare agent. The seeds also contain the less toxic, but highly homologous Ricinus communis agglutinin and the alkaloid ricinine, and especially the latter can be used to track intoxications. After oil extraction and detoxification, the defatted press cake is used as organic fertilizer and as low-value feed. In this context there have been sporadic reports from different countries describing animal intoxications after uptake of obviously insufficiently detoxified fertilizer. Observations in Germany over several years, however, have led us to speculate that the detoxification process is not always performed thoroughly and controlled, calling for international regulations which clearly state a ricin threshold in fertilizer. In this review we summarize knowledge on intended and unintended poisoning with ricin or castor seeds both in humans and animals, with a particular emphasis on intoxications due to improperly detoxified castor bean meal and forensic analysis.     

Myelin-reactive antibodies mediate the pathology of MBP-PLP fusion protein MP4-induced EAE

Experimental autoimmune encephalomyelitis (EAE) is frequently used for studies of multiple sclerosis (MS). Because in most EAE models T cells mediate the pathology in the absence of B cells/autoantibodies, the notion has evolved that also MS may be a primarily T cell-mediated disease. We have previously introduced MBP-PLP fusion protein (MP4)-induced EAE in C57BL/6 mice. Here we show that the disease in this model is antibody-dependent. Immunization of B cell-deficient mice did not induce EAE. When such B cell-deficient mice were, however, injected with MBP/PLP-specific antibodies in addition to the immunization with MP4, they developed disease of a severity and course that was similar to the wild-type mice. The deposition of antibodies in demyelinated lesions provided further evidence for the contribution of MBP/PLP-specific antibodies to CNS lesion formation. Based upon these data we suggest a two-stage model for the involvement of MBP/PLP-specific antibodies in autoimmune CNS pathology.     

Critical appraisal of the recent data published on the link between insulin and cancer

Recent publications indicate a possible association between newer analogue insulin Glargine and cancer. However all these data were observational in nature and subject to lot of methodological errors. It is practically impossible to derive at a cause and effect relationship based on these observational studies. There are several confounding factors like hyperinsulinemia, obesity and smoking, which independently can be associated with cancer risk. This review looks into the recently published observational studies from the methodological point of view and whether such a negative association can indeed be drawn as a conclusion. Several methodological defects were identified in the process of scrutiny and we concluded it is not possible to conclude that there is an association between Glargine use and cancer. However long-term prospective data is required to come to definite conclusion.     

Relative effects of CBT and pharmacotherapy in depression versus anxiety: is medication somewhat better for depression,and CBT somewhat better for anxiety?

Background: Little is known about whether cognitive behavioral therapy (CBT) or pharmacotherapy is relatively more advantageous for depressive versus anxiety disorders. Methods: We conducted a meta‐analysis wherein we searched electronic databases and references to select randomized controlled studies comparing CBT and pharmacotherapy, with or without placebo, in adults with major depressive or anxiety disorders. The primary effect size was calculated from disorder‐specific outcome measures as the difference between CBT and pharmacotherapy outcomes (i.e., positive effect size favors CBT; negative effect size favors pharmacotherapy). Results: Twenty‐one anxiety ( N = 1,266) and twenty‐one depression ( N = 2,027) studies comparing medication to CBT were included. Including all anxiety disorders, the overall effect size was.25 (95% CI: ?0.02, 0.55, P =.07). Effects for panic disorder significantly favored CBT over medications (.50, 95% CI: 0.02, 0.98). Obsessive–compulsive disorder showed similar effects‐sizes, though not statistically significant (.49, 95% CI: ?0.11, 1.09). Medications showed a nonsignificant advantage for social anxiety disorder (?.22, 95% CI: ?0.50, 0.06). The overall effect size for depression studies was.05 (95% CI: ?0.09, 0.19), with no advantage for medications or CBT. Pooling anxiety disorder and depression studies, the omnibus comparison of the relative difference between anxiety and depression in effectiveness for CBT versus pharmacotherapy pointed to a nonsignificant advantage for CBT in anxiety versus depression ( B =.14, 95% CI: ?0.14, 0.43). Conclusions: On balance, the evidence presented here indicates that there are at most very modest differences in effects of CBT versus pharmacotherapy in the treatment of anxiety versus depressive disorders. There seems to be larger differences between the anxiety disorders in terms of their relative responsiveness to pharmacotherapy versus CBT. Depression and Anxiety, 2011. © 2011 Wiley‐Liss, Inc.     

Clinical feasibility of a magnetic resonance tracking system to guide the position of the scan plane during physiologic joint motion

Purpose

Unrestricted physiologic joint motion results in multidirectional displacement of the anatomic structures. When performing real-time magnetic resonance (MR) imaging of such a joint motion, continuous adjustment of the scan plane position may be required. The purpose of this study was to evaluate the clinical feasibility of a method to guide the scan plane position during dynamic-motion MR imaging of freely moving joints.

Materials and methods

The location of a small tracker device (dedicated hardware) placed on the patient’s skin overlying a joint was determined by an ultrashort MR sequence and used to automatically adjust the scan plane position prior to each dynamic-motion MR image. Using a vertically open MR unit, this MR tracking system was applied in ten dynamic-motion MR examinations to evaluate flexion/extension manoeuvres in the weight-bearing knee joint, and in ten dynamic-motion MR examinations of the shoulder joint to evaluate manoeuvres such as internal/external rotation of the humerus, stress testing of the glenohumeral joint and abduction/adduction manoeuvres. Average number of manoeuvre repetitions, total number of images and percentage of useful images per manoeuvre were calculated. Imaging time per scan plane for each manoeuvre was recorded.

Results

Average repetition of manoeuvres varied between 1.6 and 5.8, with an average number of 7 to 18 images per manoeuvre. Average percentage of useful images varied between 61% and 89%. Total imaging time per scan plane ranged between 1 min 10 s and 4 min 51 s.

Conclusions

The MR tracking system to guide the slice position for each consecutive dynamic-motion MR image of the freely but slowly moving shoulder or knee joint was feasible for clinical use, providing a high percentage of useful images for each manoeuvre within a clinically acceptable time frame.     

Optimization of encoding gradients for MR‐ARFI

MR acoustic radiation force imaging provides a promising method to monitor therapeutic ultrasound treatments. By measuring the displacement induced by the acoustic radiation force, MR acoustic radiation force imaging can locate the focal spot, without a significant temperature rise. In this work, the encoding gradient for MR acoustic radiation force imaging is optimized to achieve an enhanced accuracy and precision of the displacement measurement. By analyzing the sources of artifacts, bulk motion and eddy currents are shown to introduce errors to the measurement, and heavy diffusion‐weighting is shown to result in noisy displacement maps. To eliminate these problems, a new encoding scheme is proposed, which utilizes a pair of bipolar gradients. Improved precision is achieved with robustness against bulk motion and background phase distortion, and improved accuracy is achieved with reduced diffusion‐weighting and optimized encoding pulse width. The experiment result shows that the signal‐to‐noise ratio can be enhanced by more than 2‐fold. These significant improvements are obtained at no cost of scan time or encoding sensitivity, enabling the detection of a displacement less than 0.l μm in a gel phantom with MR acoustic radiation force imaging. Magn Reson Med 63:1050–1058, 2010. © 2010 Wiley‐Liss, Inc.     

Single versus double-row repair of the rotator cuff

Purpose

Several techniques for arthroscopic repair of rotator cuff defects have been introduced over the past years. Besides established techniques such as single-row repairs, new techniques such as double-row reconstructions have gained increasing interest. The present article therefore provides an overview of the currently available literature on both repair techniques with respect to several anatomical, biomechanical, clinical and structural endpoints.

Methods

Systematic literature review of biomechanical, clinical and radiographic studies investigating or comparing single- and double-row techniques. These results were evaluated and compared to provide an overview on benefits and drawbacks of the respective repair type.

Results

Reconstructions of the tendon-to-bone unit for full-thickness tears in either single- or double-row technique differ with respect to several endpoints. Double-row repair techniques provide more anatomical reconstructions of the footprint and superior initial biomechanical characteristics when compared to single-row repair. With regard to clinical results, no significant differences were found while radiological data suggest a better structural tendon integrity following double-row fixation.

Conclusion

Presently published clinical studies cannot emphasize a clearly superior technique at this time. Available biomechanical studies are in favour of double-row repair. Radiographic studies suggest a beneficial effect of double-row reconstruction on structural integrity of the reattached tendon or reduced recurrent defect rates, respectively.