Amputation, phantom pain and subjective well-being: a qualitative study

The purpose of this qualitative study was to explore the impact of an amputation and of phantom pain on the subjective well-being of amputees. Sixteen lower-limb amputees were interviewed. A semi-structured interview and two Visual Analogue Scales were used. To interpret the results, a new socio-medical model joining two models, 'The Disablement Process model' and the 'Social Production Function theory', was used. Questions were asked concerning the factors influencing patients' subjective well-being prior to, at the time of and after an amputation. These factors were patients' medical history, their phantom sensations and phantom pain, their daily activities, the social support they received, and the influence of an amputation and phantom pain on long-term behaviour and on their subjective well-being. All factors were found to have an influence on the individual's subjective well-being. All these factors, however, seemed to reinforce each other. Therefore, the greatest influence of factors on subjective well-being occurred when more than one factor was involved. Substituting certain activities by others then becomes less and less effective in inducing a sense of subjective well-being.     

Elucidation of the spatial ventricular gradient and its link with dispersion of repolarization.

The ventricular gradient, a notion conceived by Wilson et al during the 1930s, has contributed considerably to a better understanding of the ECG manifestations of the cardiac repolarization process. The power of the ventricular gradient is its ability to assess the primary factors that contribute to the T wave (i.e., heterogeneity of action potential morphology throughout the ventricles) in the presence of secondary factors contributing to the T wave (i.e., heterogeneity in ventricular depolarization instants). Where T-wave morphology is an ECG expression of heterogeneity of the repolarization, the ventricular gradient discriminates between primary or secondary causes of such heterogeneity. Besides the spatial ventricular gradient (Burger's three-dimensional elaboration of Wilson's two-dimensional concept), body surface mapping of local components of the ventricular gradient has emerged as a technique for assessing local ventricular action potential duration heterogeneity. The latter is believed to contribute to localization of arrhythmogenic areas in the heart. The spatial ventricular gradient, which can be computed on the basis of a regular routine ECG and does not require body surface mapping, aims to assess the overall heterogeneity of ventricular action potential morphology. This review addresses the nature and diagnostic potential of the spatial ventricular gradient. The main focus is the role of the spatial ventricular gradient in ECG assessment of dispersion of repolarization, a key factor in arrhythmogeneity.     

Severe hepatic side effects of ezetimibe.

BACKGROUND AND AIMS: Ezetimibe was introduced recently as a new class of cholesterol-lowering drugs. Until now only limited increases of transaminase levels were reported. METHODS: We studied 2 patients with severe hepatic side effects of ezetimibe in a general community hospital. RESULTS: Ezetimibe may lead to 2 distinct types of severe hepatic side effects. CONCLUSIONS: Ezetimibe may rarely cause hepatotoxicity, severe cholestatic hepatitis, or acute autoimmune hepatitis.     

Theoretical perspectives and applications of group learning in PBL

An essential part of problem-based learning (PBL) is group learning. Thus, an in depth understanding of the theoretical underpinnings of group learning in PBL allows educators to bridge theory and practice more effectively thus providing ideas and tools to enhance PBL practices and research. The theory-driven applications examined in this article establish grounds for future research in PBL. The purpose of this article is to describe and examine two theoretical perspectives of group learning in PBL and their potential applications to improve educational practice. They include: (1) social interdependence theory and the meaning of positive interdependence, (2) socio cognitive theory of networked expertise and the concept of knowledge creation in innovative knowledge communities (IKC). Potential applications include the following: development of instructional material to foster positive interdependency using concept maps; formal and structured use of peer feedback throughout PBL courses to promote individual and group accountability; creation and sharing of new knowledge about different topics within and across IKC; and use of rotating students with hybrid abilities across PBL groups to foster distributed cognition.     

Power analysis in randomized clinical trials based on item response theory

Patient relevant outcomes, measured using questionnaires, are becoming increasingly popular endpoints in randomized clinical trials (RCTs). Recently, interest in the use of item response theory (IRT) to analyze the responses to such questionnaires has increased. In this paper, we used a simulation study to examine the small sample behavior of a test statistic designed to examine the difference in average latent trait level between two groups when the two-parameter logistic IRT model for binary data is used. The simulation study was extended to examine the relationship between the number of patients required in each arm of an RCT, the number of items used to assess them, and the power to detect minimal, moderate, and substantial treatment effects. The results show that the number of patients required in each arm of an RCT varies with the number of items used to assess the patients. However, as long as at least 20 items are used, the number of items barely affects the number of patients required in each arm of an RCT to detect effect sizes of 0.5 and 0.8 with a power of 80%. In addition, the number of items used has more effect on the number of patients required to detect an effect size of 0.2 with a power of 80%. For instance, if only five randomly selected items are used, it is necessary to include 950 patients in each arm, but if 50 items are used, only 450 are required in each arm. These results indicate that if an RCT is to be designed to detect small effects, it is inadvisable to use very short instruments analyzed using IRT. Finally, the SF-36, SF-12, and SF-8 instruments were considered in the same framework. Since these instruments consist of items scored in more than two categories, slightly different results were obtained.     

Evoked phase synchronization between adjacent high-density electrodes in human scalp EEG: duration and time course related to behavior.

OBJECTIVE: Data from a previous event-related potential (ERP) study in visual-perceptual grouping [Nikolaev AR, van Leeuwen C. Flexibility in spatial and non-spatial feature grouping: an event-related potentials study. Brain Res Cogn Brain Res 2004;22:13-25] were re-analyzed to identify event-related dynamics of phase-synchronization. METHODS: In 20 Hz activity, uniform spreading of phase synchronization in closely spaced (approximately 2 cm) scalp electrodes appears and disappears spontaneously. The lengths of synchronized activity intervals and how they vary as a function of stimulus presentation were compared between task and control conditions. RESULTS: Synchronization reached a maximum in the task condition about 180 ms post-stimulus onset, coinciding with the peak N180 ERP marking the deployment of task-specific attention. Synchronized intervals were longer in the task than in the control condition. Long (above 80 ms) intervals occurred at a stable rate before and just after stimulus onset, but steeply decreased 200-400 ms afterwards. CONCLUSIONS: Perceptual tasks lead to longer synchronized intervals in early visual areas. Attention deployment resets the ongoing synchronization. Event-related activity, besides low-frequency ERP, consists of high-frequency short and long synchronized intervals corresponding to evoked bursts and ongoing oscillations, respectively. SIGNIFICANCE: High-density scalp recorded EEG revealed synchronization dynamics in a local, early visual area of cortex that can be interpreted as modulation of spontaneous ongoing task-related processes by attention.