Stability-dependent behavioural and electro-cortical reorganizations during intentional switching between bimanual tapping modes

This study investigated behavioural and electro-cortical reorganizations accompanying intentional switching between two distinct bimanual coordination tapping modes (In-phase and Anti-phase) that differ in stability when produced at the same movement rate. We expected that switching to a less stable tapping mode (In-to-Anti switching) would lead to larger behavioural perturbations and require supplementary neural resources than switching to a more stable tapping mode (Anti-to-In switching). Behavioural results confirmed that the In-to-Anti switching lasted longer than the Anti-to-In switching. A general increase in attention-related neural activity was found at the moment of switching for both conditions. Additionally, two condition-dependent EEG reorganizations were observed. First, a specific increase in cortico-cortical coherence appeared exclusively during the In-to-Anti switching. This result may reflect a strengthening in inter-regional communication in order to engage in the subsequent, less stable, tapping mode. Second, a decrease in motor-related neural activity (increased beta spectral power) was found for the Anti-to-In switching only. The latter effect may reflect the interruption of the previous, less stable, tapping mode. Given that previous results on spontaneous Anti-to-In switching revealing an inverse pattern of EEG reorganization (decreased beta spectral power), present findings give new insight on the stability-dependent neural correlates of intentional motor switching. © 2010 Elsevier Ireland Ltd. All rights reserved

Importance of polyethylene thickness in total shoulder arthroplasty: a finite element analysis.

BACKGROUND: Articular surfaces reconstruction is essential in total shoulder arthroplasty. Because of the limited glenoid bone support, thin glenoid component could improve anatomical reconstruction, but adverse mechanical effects might appear. METHODS: With a numerical musculoskeletal shoulder model, we analysed and compared three values of thickness of a typical all-polyethylene glenoid component: 2, 4 (reference) and 6mm. A loaded movement of abduction in the scapular plane was simulated. We evaluated the humeral head translation, the muscle moment arms, the joint force, the articular contact pattern, and the polyethylene and cement stress. Findings Decreasing polyethylene thickness from 6 to 2mm slightly increased humeral head translation and muscle moment arms. This induced a small decreased of the joint reaction force, but important increase of stress within the polyethylene and the cement mantel. Interpretation The reference thickness of 4mm seems a good compromise to avoid stress concentration and joint stuffing.

Functional compensation of motor function in pre-symptomatic Huntington's disease.

Involuntary choreiform movements are a clinical hallmark of Huntington's disease. Studies in clinically affected patients suggest a shift of motor activations to parietal cortices in response to progressive neurodegeneration. Here, we studied pre-symptomatic gene carriers to examine the compensatory mechanisms that underlie the phenomenon of retained motor function in the presence of degenerative change. Fifteen pre-symptomatic gene carriers and 12 matched controls performed button presses paced by a metronome at either 0.5 or 2 Hz with four fingers of the right hand whilst being scanned with functional magnetic resonance imaging. Subjects pressed buttons either in the order of a previously learnt 10-item finger sequence, from left to right, or kept still. Error rates ranged from 2% to 7% in the pre-symptomatic gene carriers and from 0.5% to 4% in controls, depending on the condition. No significant difference in task performance was found between groups for any of the conditions. Activations in the supplementary motor area (SMA) and superior parietal lobe differed with gene status. Compared with healthy controls, gene carriers showed greater activations of left caudal SMA with all movement conditions. Activations correlated with increasing speed of movement were greater the closer the gene carriers were to estimated clinical diagnosis, defined by the onset of unequivocal motor signs. Activations associated with increased movement complexity (i.e. with the pre-learnt 10-item sequence) decreased in the rostral SMA with nearing diagnostic onset. The left superior parietal lobe showed reduced activation with increased movement complexity in gene carriers compared with controls, and in the right superior parietal lobe showed greater activations with all but the most demanding movements. We identified a complex pattern of motor compensation in pre-symptomatic gene carriers. The results show that preclinical compensation goes beyond a simple shift of activity from premotor to parietal regions involving multiple compensatory mechanisms in executive and cognitive motor areas. Critically, the pattern of motor compensation is flexible depending on the actual task demands on motor control.

Letter to the Editor : on the value of probability for evaluating results of comparative pattern analyses

This letter to the Editor comments on the article Practical relevance of pattern uniqueness in forensic science by P.T. Jayaprakash (Forensic Science International, in press).

Evaluating fear of falling among community-dwelling older people: A qualitative pattern model based on the experience of falls

This research was conducted in the context of the project IRIS 8A Health and Society (2002-2008) and financially supported by the University of Lausanne. It was aomed at developping a model based on the elder people's experience and allowed us to develop a "Portrait evaluation" of fear of falling using their examples and words. It is a very simple evaluation, which can be used by professionals, but by the elder people themselves. The "Portrait evaluation" and the user's guide are on free access, but we would very much approciate to know whether other people or scientists have used it and collect their comments. (contact: Chantal.Piot-Ziegler@unil.ch)The purpose of this study is to create a model grounded in the elderly people's experience allowing the development of an original instrument to evaluate FOF.In a previous study, 58 semi-structured interviews were conducted with community-dwelling elderly people. The qualitative thematic analysis showed that fear of falling was defined through the functional, social and psychological long-term consequences of falls (Piot-Ziegler et al., 2007).In order to reveal patterns in the expression of fear of falling, an original qualitative thematic pattern analysis (QUAlitative Pattern Analysis - QUAPA) is developed and applied on these interviews.The results of this analysis show an internal coherence across the three dimensions (functional, social and psychological). Four different patterns are found, corresponding to four degrees of fear of falling. They are formalized in a fear of falling intensity model.This model leads to a portrait-evaluation for fallers and non-fallers. The evaluation must be confronted to large samples of elderly people, living in different environments. It presents an original alternative to the concept of self-efficacy to evaluate fear of falling in older people.The model of FOF presented in this article is grounded on elderly people's experience. It gives an experiential description of the three dimensions constitutive of FOF and of their evolution as fear increases, and defines an evaluation tool using situations and wordings based on the elderly people's discourse.

Pain pattern and left internal mammary artery grafting.

BACKGROUND: This study was designed to determine whether the pain pattern in patients with an internal mammary artery (IMA) harvest differs from that in other cardiac operations and whether these patients present specific characteristics with clinical implications. METHODS: One hundred patients with left IMA grafting (IMA group) were compared prospectively with 100 patients who had a heart operation without IMA harvest (non-IMA group). Pain assessment was performed on postoperative days (POD) 1, 2, 3, and 7, and included pain intensity (10-point scale) and pain localization. RESULTS: In the IMA group, pain intensity was higher on POD 2 (4.2 +/- 2.4 versus 3.2 +/- 2.3, p < 0.01), and there were more patients without pain on POD 7 (32 versus 19, p = 0.03). In the IMA group, more patients had left basal thoracic pain throughout the entire study period and had sternal pain on POD 7, whereas more patients in the non-IMA group complained about back pain during the early postoperative period. CONCLUSIONS: The impact of IMA harvest on pain intensity is moderate, but the pain localization pattern of each group exhibits specific features that could help to better target pain management.

Assessing the epidemiology and pattern of care of colorectal cancer in Valais, Switzerland

Background: The Valais's cancer registry (RVsT) of the Observatoire valaisan de le santé (OVS) and the department of oncology of Valais's Hospital conducted a study on the epidemiology and pattern of care of colorectal cancer in Valais. Colorectal cancer is the third cause of death by cancer in Switzerland with about 1600 deaths per year. It is the third most frequent cancer for males and the second most frequent for females in Valais. The number of new colorectal cancer cases (average per year) increased between 1989 and 2009 for males as well as for females in Valais. The number of colorectal cancer death cases (average per year) slightly increased between 1989 and 2009 for males as well as for females in Valais. Age-standardized rates of incidence were stable for males and females in Valais and in Switzerland between 1989 and 2009, while age-standardized rates of mortality decreased for males and females in Valais and Switzerland. Results: 774 cases were recorded (59% males). Median age at diagnosis was 70 years old. Most of cancers were invasive (79%) and the main localization was the colon (71%). The most frequent mode of detection was a consultation for non emergency symptoms (75%), but almost 10% of patients consulted in emergency. 82% of patients were treated within 30 days from diagnosis. 90% of the patients were treated by surgery alone or with combined treatment. The first treatment was surgery, including endoscopic resection in 86% of the cases. The treatment was different according to the localization and the stage of the cancer. Survival rate was 95% at 30 days and 79% at one year. The survival was dependent on the stage and the age at diagnosis. Cox model shows an association between mortality and age (better survival for young people) and between mortality and stage (better survival for the lower stages). Methods: RVsT collects information on all cancer cases since 1989 for people registered in the communes of Valais. RVsT has an authorization to collect non anonymized data. All new incident cancers are coded according to the International Classification of Diseases for Oncology (ICD-O-3) and the stages are coded according to the TNM classification. We studied all cases of in situ and invasive colorectal cancers diagnosed between 2006 and 2009 and registered routinely at the RVsT. We checked for data completeness and if necessary sent questionnaires to avoid missing data. A distance of 15 cm has been chosen to delimitate the colon (sigmoid) and the rectal cancers. We made an active follow-up for vital status to have a valid survival analysis. We analyzed the characteristics of the tumors according to age, sex, localization and stage with stata 9 software. Kaplan-Meier curves were generated and Cox model were fitted to analyze survival. Conclusion: The characteristics of patients and tumors and the one year survival were similar to those observed in Switzerland and some European countries. Patterns of care were close to those recommended in guidelines. Routine data recorded in a cancer registry can be used, not only to provide general statistics, but also to help clinicians assess local practices.

Psychomotor retardation in depression: bradykinesia or paucity of movement?

Objectives: Psychomotor retardation is part of Major Depression (MD) diagnosis criteria and has been assimilated to bradykinesia, even though there is a clear lack of objective measurement of motor activity in MD. We conducted a study to evaluate bradykinesia, posture and gait parameters in MD patients with an ambulatory system, allowing continuous motor measurements. Methods: Patients with DSM-IV MD and healthy controls matched for age and sex were asked to carry on with their usual activities while being recorded for 6 hours by a wireless autonomous ambulatory system, containing miniature gyroscopes, data-logger, battery and flash memory. allowing continuous recording of upper limbs movements (speed, amplitude and activity (% of time with movement)), posture (% of time standing, walking, lying or sitting) and gait parameters (speed, cadence, stance, double support, stride). Results: Hands activity was significantly lower in depressed patients, as compared to controls (MD: 40%, controls: 60%; p<0.05). Speed of hand movements (p= 0.13) and their amplitude (p=0.71) were similar to controls. MD patients had a trend to spend more time lying or sitting than controls (p=0.06) but did not differ in terms of any gait parameters. Conclusion: Patients with MD displayed less hand movements than controls and tended to spend more time lying or sitting over 6 hours, but did not differ in terms of speed and amplitude of movement, nor in gait parameters. These results suggest that psychomotor retardation classically described in MD might be the expression of a paucity of movement rather than a bradykinesia as observed in parkinsonism and might involved different (nondopaminergic) mechanisms.

Remorin, a solanaceae protein resident in membrane rafts and plasmodesmata, impairs potato virus X movement.

Remorins (REMs) are proteins of unknown function specific to vascular plants. We have used imaging and biochemical approaches and in situ labeling to demonstrate that REM clusters at plasmodesmata and in approximately 70-nm membrane domains, similar to lipid rafts, in the cytosolic leaflet of the plasma membrane. From a manipulation of REM levels in transgenic tomato (Solanum lycopersicum) plants, we show that Potato virus X (PVX) movement is inversely related to REM accumulation. We show that REM can interact physically with the movement protein TRIPLE GENE BLOCK PROTEIN1 from PVX. Based on the localization of REM and its impact on virus macromolecular trafficking, we discuss the potential for lipid rafts to act as functional components in plasmodesmata and the plasma membrane.

Mouvements anormaux et accident vasculaire cérébral [Movement disorders in stroke]

Dyskinesias are infrequent presentations in acute stroke (1%). They can be found more frequently as delayed presentations after a stroke, but the prevalence is not available from the literature. The full spectrum of hyper- and hypo-akinetic syndromes has been described, but three main pictures are rather specific of an acute stroke: limb shaking, hemichorea-hemiballism and unilateral asterixis. Besides limb shaking, that seems to reflect a transient diffuse ischemia of the frontosubcortical motor pathway, lesions are described at all levels of the frontosubcortical motor circuit including the sensorimotor frontoparietal cortex, the striatum, the pallidum, the thalamic nuclei, the subthalamic nucleus, the substantia nigra, the cerebellum, the brainstem and their interconnecting pathways, as ischemic or hemorrhagic strokes. The preferentially late development of dyskinesia could reflect the return to a more ancestral motor control level, the most functional possible with the remaining configuration of structures, elaborated by brain plasticity after stroke.

The primary in vivo immune response to Mls-1 (Mtv-7 sag). Route of injection determines the immune response pattern.

Injection of cells expressing the retroviral superantigen Mls-1 (Mtv-7 sag) into adult Mls-1- mice induces a strong immune response including both T- and B-cell activation. This model was used for studying qualitative aspects of the immune response in normal mice with a defined antigen-presenting cell (the B cell) and without the use of adjuvant. BALB/c mice were injected locally or systemically with Mls-1-expressing spleen cells from Mls-1-congenic BALB.D2 mice. Intravenous injection led to an initially strong expansion of Mls-1-reactive V beta 6+ CD4+ cells mainly in the spleen, to a large degree explained by the trapping of reactive cells, and a rapid down-regulation of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production, consistent with the proposed tolerogenic property of B cells as antigen-presenting cells. However, these mice developed a slowly appearing but persistent B-cell response dominated by IgG1-producing cells, suggesting a shift in lymphokines produced rather than complete unresponsiveness. Subcutaneous injection into the hind footpad with the same number of cells led to a strong local response in the draining lymph node, characterized by a dramatic increase of V beta 6+ CD4+ T cells, local production of IL-2 and IFN-gamma and a strong but short-lived antibody response dominated by IgG2a-producing cells, characteristic of a T-helper type 1 (Th1) type of response. Both routes of injection led ultimately to deletion of reactive T cells and anergy, as defined by the inability to produce IL-2 upon in vitro stimulation with Mls-1. It is concluded that Mls-1 presented by B cells induces qualitatively different responses in vivo dependent on the route of injection. We propose that the different responses result from the migration of the injected cells to different micro-anatomical sites in the lymphoid tissue. Furthermore, these results suggest that B cells may function as professional antigen-presenting cells in vivo present in an appropriate environment.

Lake dwellers occupation gap in Lake Geneva (France-Switzerland) possibly explained by an earthquake-mass movement-tsunami event during Early Bronze Age

High-resolution seismic and sediment core data from the 'Grand Lac' basin of Lake Geneva reveal traces of repeated slope instabilities with one main slide-evolved mass-flow (minimum volume 0.13 km3) that originated from the northern lateral slope of the lake near the city of Lausanne. Radiocarbon dating of organic remains sampled from the top of the main deposit gives an age interval of 1865-1608 BC. This date coincides with the age interval for a mass movement event described in the 'Petit Lac' basin of Lake Geneva (1872-1622 BC). Because multiple mass movements took place at the same time in different parts of the lake, we consider the most likely trigger mechanism to be a strong earthquake (Mw 6) that occurred in the period between 1872 and 1608 BC. Based on numerical simulations, we show the major deposit near Lausanne would have generated a tsunami with local wave heights of up to 6 m. The combined effects of the earthquake and the following tsunami provide a possible explanation for a gap in lake dwellers occupation along the shores of Lake Geneva revealed by dendrochronological dating of two palafitte archaeological sites.

Cerebral aneurysm exclusion by CT angiography based on subarachnoid hemorrhage pattern: a retrospective study.

BACKGROUND: To identify patients with spontaneous subarachnoid hemorrhage for whom CT angiography alone can exclude ruptured aneurysms. METHODS: An observational retrospective review was carried out of all consecutive patients with non-traumatic subarachnoid hemorrhage who underwent both CT angiography and catheter angiography to exclude an aneurysm. CT angiography negative cases (no aneurysm) were classified according to their CT hemorrhage pattern as "aneurismal", "perimesencephalic" or as "no-hemorrhage." RESULTS: Two hundred and forty-one patients were included. A CT angiography aneurysm detection sensitivity and specificity of 96.4% and 96.0% were observed. All 35 cases of perimesencephalic or no-hemorrhage out of 78 CT angiography negatives also had negative angiography findings. CONCLUSIONS: CT angiography is self-reliant to exclude ruptured aneurysms when either a perimesencephalic hemorrhage or no-hemorrhage pattern is identified on the CT within a week of symptom onset.