Relocalization of neuronal nitric oxide synthase (nNOS) as a marker for complete restoration of the dystrophin associated protein complex in skeletal muscle

A lack of effective treatments for Duchenne muscular dystrophy, a fatal X-linked myopathy, has focused attention on the possibility of gene therapy. The aim of the gene therapy approach is the restoration of the dystrophin associated complex of proteins, one member of which is neuronal nitric oxide synthase, an important enzyme in signal transduction. Transgenic mdx mice and plasmid gene transfer of both human and murine recombinant dystrophins was used to assess whether nNOS could be restored to the sarcolemma following dystrophin gene transfer at a variety of levels of expression. Murine revertant fibres and human patients with different dystrophin deletions were used to assess the relationship between exon deletion and loss of neuronal nitric oxide synthase localization to the sarcolemma. We demonstrate that the domain encoded by exons 45-48 is required for localization of neuronal nitric oxide synthase to the sarcolemma. On the basis of these observations we suggest that neuronal nitric oxide synthase is a useful marker for complete restoration of the dystrophin associated complex and should be used as one of the criteria for selecting the recombinant molecule to be used for gene therapy in Duchenne muscular dystrophy.     

Emergency/Adjunct services and attrition prevention for randomized clinical trials in children: the MTA manual-based solution

Treatment studies in child and adolescent psychiatry are increasingly characterized by long-term, multisite, randomized clinical trials (RCTs). During the course of these RCTs it is common for clinical exigencies to emerge that require rapid, direct intervention. The challenge is to provide clinically appropriate responses that do not contaminate the delivery, distinctness, and interpretation of the treatments under investigation. In multisite studies, the problem is compounded by the need to minimize cross-site differences in the delivery of adjunct treatments. Such minimization requires fully operationalized and manual-based procedures for clinically mandated intervention. The NIMH Collaborative Multisite Multimodal Treatment Study of Children With Attention-Deficit/Hyperactivity Disorder (ADHD)--"the MTA"--is a long-term multisite collaborative study in which children with ADHD were randomly assigned to either medication management, behavioral treatment, the combination, or community-comparison assessment and referral. In designing its study, the MTA developed a manual-based set of procedures (the MTA Adjunct Services and Attrition Prevention [ASAP] Manual) for situations not covered by the protocol treatments. The majority of cases requiring adjunct services fell into two major categories: (1) crisis/emergent situations and (2) imminent risk of attrition. This report describes the ASAP guidelines for dealing with cases that required adjunct services that the MTA Steering Committee adopted before initiating the trial. Although the manual-based guidelines are especially applicable to multisite RCTs, many of the procedures in the ASAP Manual can apply to any treatment study in children.     

The uptake of technologies designed to influence medication safety in Canadian hospitals

Background There are many technologies designed to improve medication safety. Although limited evidence supports their use, there are pressures to implement them. Objective To determine the uptake of technologies designed to improve medication safety, plans for adopting technologies, attitudes towards technology use, and perceptions of medication error. Methods We performed a cross‐sectional survey of pharmacy directors at Canada’s 100 largest acute‐care hospitals. Results Seventy‐eight per cent of surveyed hospitals responded. Responding hospitals averaged 499 beds and 29% were teaching facilities. Hospital frequently used clinical pharmacy services (97% of hospitals), pharmacy‐based intravenous admixture services (81%), computerized decision support modules for pharmacy order entry systems (77%), unit‐dose drug distribution systems (75%) and computerized medication administration records (67%). Hospitals infrequently used bar‐coding (9% of hospitals) and computerized physician order entry (9%). A majority of respondents and hospitals favoured expanded use of new technologies and planned for increased uptake. Respondents chose as their hospital’s next investment: automated dispensing (33%), bar‐coding (25%) and computerized physician order entry (12%). Conclusion Canadian hospitals appear poised to make sizeable investments in poorly evaluated technologies that address medication safety.     

A unified framework for clustering and quantitative analysis of white matter fiber tracts

We present a novel approach for joint clustering and point-by-point mapping of white matter fiber pathways. Knowledge of the point correspondence along the fiber pathways is not only necessary for accurate clustering of the trajectories into fiber bundles, but also crucial for any tract-oriented quantitative analysis. We employ an expectation-maximization (EM) algorithm to cluster the trajectories in a gamma mixture model context. The result of clustering is the probabilistic assignment of the fiber trajectories to each cluster, an estimate of the cluster parameters, i.e. spatial mean and variance, and point correspondences. The fiber bundles are modeled by the mean trajectory and its spatial variation. Point-by-point correspondence of the trajectories within a bundle is obtained by constructing a distance map and a label map from each cluster center at every iteration of the EM algorithm. This offers a time-efficient alternative to pairwise curve matching of all trajectories with respect to each cluster center. The proposed method has the potential to benefit from an anatomical atlas of fiber tracts by incorporating it as prior information in the EM algorithm. The algorithm is also capable of handling outliers in a principled way. The presented results confirm the efficiency and effectiveness of the proposed framework for quantitative analysis of diffusion tensor MRI.     

Skeletal muscle metabolic dysfunction in obesity and metabolic syndrome

Obesity and the related metabolic syndrome have become a worldwide epidemic. Inactivity appears to be a primary causative factor in the pathogenesis of this obesity and metabolic syndrome. There are two possible, perhaps not mutually exclusive, events that may lead to intramyocellular lipid accumulation and mitochondrial dysfunction in patients with obesity. First, obesity, with high intake-associated lipid accumulation in muscle may interfere with cellular mitochondrial function through generation of reactive oxygen species leading to lipid membrane peroxidative injury and disruption of mitochondrial membrane-dependent enzymes. This in turn leads to impaired oxidative metabolism. Secondly, a primary defect in mitochondrial oxidative metabolism may be responsible for a reduction in fatty acid oxidation leading to intramyocellular lipid accumulation as a secondary event. Non-invasive techniques such as proton (1H) and phosphorus (31P) magnetic resonance spectroscopy, coupled with specific magnetic resonance imaging techniques, may facilitate the investigation of the effects of various ergometric interventions on the pathophysiology of obesity and the metabolic syndrome. Exercise has positive effects on glucose metabolism, aerobic metabolism, mitochondrial density, and respiratory chain proteins in patients with metabolic syndrome, and we propose that this may be due to the exercise effects on AMP kinase, and a prospective physiological mechanism for this benefit is presented. A physiological model of the effect of intramyocellular lipid accumulation on oxidative metabolism and insulin mediated glucose uptake is proposed.