The role of Mg2+ in the inactivation of inwardly rectifying K+ channels in aortic endothelial cells.

We have studied the role of Mg2+ in the inactivation of inwardly rectifying K+ channels in vascular endothelial cells. Inactivation was largely eliminated in Mg(2+)-free external solutions and the extent of inactivation was increased by raising Mg2+o. The dose-response relation for the reduction of channel open probability showed that Mg2+o binds to a site (KD = approximately 25 microM at -160 mV) that senses approximately 38% of the potential drop from the external membrane surface. Analysis of the single-channel kinetics showed that Mg2+ produced a class of long-lived closures that separated bursts of openings. Raising Mg2+o reduced the burst duration, but less than expected for an open-channel blocking mechanism. The effects of Mg2+o are antagonized by K+o in manner which suggests that K+ competes with Mg2+ for the inactivation site. Mg2+o also reduced the amplitude of the single-channel current at millimolar concentrations by a rapid block of the open channel. A mechanism is proposed in which Mg2+ binds to the closed channel during hyperpolarization and prevents it from opening until it is occupied by K+

Undertaking clinical audit, with reference to a Prescribing Observatory for Mental Health audit of lithium monitoring

Audit is an important tool for quality improvement. The collection of data on clinical performance against evidence-based and clinically relevant standards, which are considered by clinicians to be realistic in routine practice, can usefully prompt reflective practice and the implementation of change. Evidence of participation in clinical audit is required to achieve intended learning outcomes for trainees in psychiatry and revalidation for those who are members of the Royal College of Psychiatrists. This article addresses some of the practical steps involved in conducting an audit project, and, to illustrate key points, draws on lessons learnt from a national, audit-based, quality improvement programme of lithium prescribing and monitoring conducted through the Prescribing Observatory for Mental Health

How to Strengthen and Reform Indian Medical Education System: Is Nationalization the Only Answer?

As India marches towards an exciting new future of growth and progress, medical education will play pivotal role in crafting a sustained development agenda. Efforts have to be undertaken to create a medical educational system that nourishes innovation, entrepreneurship and addresses the skill requirement of the growing economy. Last decade has been witness to phenomenal growth in numbers of the medical colleges, nursing colleges and other similar training institutions. This unregulated rapid growth in number of medical colleges has adversely impacted quality of training in India’s medical institutions. The policy of privatization of medical care has seriously undermined health services and further limited the access of the underprivileged. Therefore the only solution is centralization or nationalization or globalization of the entire medical education and health sectors or to join hands with world health organization, So that a uniform health cares facility can be given to each and every human being

Steps in immunosuppression for renal transplantation

The authors provide a historical survey of the immunosuppressive agents that have been used to prevent allograft rejection. Attention is given to the expected effect of cyclosporin in kidney translations

Effect of music-movement synchrony on exercise oxygen consumption

The published full-text article can be accessed at the link below.AIM: Past research indicates that endurance is improved when exercise movements are synchronised with a musical beat, however it is unclear whether such benefits are associated with reduced metabolic cost. We compared oxygen consumption (VO2) and related physiological effects of exercise conducted synchronously and asynchronously with music. METHODS: Three music tracks, each recorded at three different tempi (123, 130, and 137 beats.min-1), accompanied cycle ergometry at 65 pedal revolutions.min-1. Thus three randomly-assigned experimental conditions were administered: slow tempo asynchronous, synchronous, and fast tempo asynchronous. Exercise response of VO2, HR, and ratings of perceived exertion (RPE), to each condition was monitored in 10 untrained male participants aged 21.7±0.8 years (mean±SD) who cycled for 12 min at 70% maximal heart rate (HR). RESULTS: Mean VO2 differed among conditions (P=0.008), being lower in the synchronous (1.80±0.22 L.min-1) compared to the slow tempo asynchronous condition (1.94±0.21 L.min-1; P<0.05). There was no difference in HR or RPE among conditions, although HR showed a similar trend to VO2. CONCLUSION: The present results indicate that exercise is more efficient when performed synchronously with music than when musical tempo is slightly slower than the rate of cyclical movement

Manifold Learning in MR spectroscopy using nonlinear dimensionality reduction and unsupervised clustering

Purpose To investigate whether nonlinear dimensionality reduction improves unsupervised classification of 1H MRS brain tumor data compared with a linear method. Methods In vivo single-voxel 1H magnetic resonance spectroscopy (55 patients) and 1H magnetic resonance spectroscopy imaging (MRSI) (29 patients) data were acquired from histopathologically diagnosed gliomas. Data reduction using Laplacian eigenmaps (LE) or independent component analysis (ICA) was followed by k-means clustering or agglomerative hierarchical clustering (AHC) for unsupervised learning to assess tumor grade and for tissue type segmentation of MRSI data. Results An accuracy of 93% in classification of glioma grade II and grade IV, with 100% accuracy in distinguishing tumor and normal spectra, was obtained by LE with unsupervised clustering, but not with the combination of k-means and ICA. With 1H MRSI data, LE provided a more linear distribution of data for cluster analysis and better cluster stability than ICA. LE combined with k-means or AHC provided 91% accuracy for classifying tumor grade and 100% accuracy for identifying normal tissue voxels. Color-coded visualization of normal brain, tumor core, and infiltration regions was achieved with LE combined with AHC. Conclusion Purpose To investigate whether nonlinear dimensionality reduction improves unsupervised classification of 1H MRS brain tumor data compared with a linear method. Methods In vivo single-voxel 1H magnetic resonance spectroscopy (55 patients) and 1H magnetic resonance spectroscopy imaging (MRSI) (29 patients) data were acquired from histopathologically diagnosed gliomas. Data reduction using Laplacian eigenmaps (LE) or independent component analysis (ICA) was followed by k-means clustering or agglomerative hierarchical clustering (AHC) for unsupervised learning to assess tumor grade and for tissue type segmentation of MRSI data. Results An accuracy of 93% in classification of glioma grade II and grade IV, with 100% accuracy in distinguishing tumor and normal spectra, was obtained by LE with unsupervised clustering, but not with the combination of k-means and ICA. With 1H MRSI data, LE provided a more linear distribution of data for cluster analysis and better cluster stability than ICA. LE combined with k-means or AHC provided 91% accuracy for classifying tumor grade and 100% accuracy for identifying normal tissue voxels. Color-coded visualization of normal brain, tumor core, and infiltration regions was achieved with LE combined with AHC. Conclusion The LE method is promising for unsupervised clustering to separate brain and tumor tissue with automated color-coding for visualization of 1H MRSI data after cluster analysis