Termination of tachycardias by interrupting blood flow to the arrhythmogenic area

The hypothesis that production of ischemia or cooling of an arrhythmogenic area or pathway could interrupt tachycardias was tested by subselective catheterization of the coronary artery supplying the site of origin of ventricular tachycardia (9 patients), the accessory pathway (2 patients) and the site of origin of atrial tachycardia (1 patient). Ventricular tachycardia was reproducibly terminated and reinduction temporarily prevented in 8 of the 9 patients by occlusion of the artery or administration of iced isotonic saline. Block in the accessory pathway was obtained in 1 of the 2 patients with Wolff-Parkinson-White syndrome. Selective cooling through the atrioventricular nodal artery in 1 patient terminated his circus movement tachycardia. Reproducible termination of a continuous atrial tachycardia was obtained by cooling of the atrial branch supplying the site of origin of the arrhythmia. These data demonstrate the feasibility of identification and selective catheterization of the coronary artery branch supplying blood to an arrhythmogenic area or pathway and suggest a new possibility for treatment of tachycardias by permanently blocking the blood supply to the site of origin or pathway of a tachycardia.     

Center or side: biases in selecting grasp points on small bars

Choosing appropriate grasp points is necessary for successfully interacting with objects in our environment. We brought two possible determinants of grasp point selection into conflict: the attempt to grasp an object near its center of mass to minimize torque and ensure stability and the attempt to minimize movement distance. We let our participants grasp two elongated objects of different mass and surface friction that were approached from different distances to both sides of the object. Maximizing stability predicts grasp points close to the object’s center, while minimizing movement costs predicts a bias of the grasp axis toward the side at which the movement started. We found smaller deviations from the center of mass for the smooth and heavy object, presumably because the larger torques and more slippery surface for the heavy object increase the chance of unwanted object rotation. However, our right-handed participants tended to grasp the objects to the right of the center of mass, irrespective of where the movement started. The rightward bias persisted when vision was removed once the hand was half way to the object. It was reduced when the required precision was increased. Starting the movement above the object eliminated the bias. Grasping with the left hand, participants tended to grasp the object to the left of its center. Thus, the selected grasp points seem to reflect a compromise between maximizing stability by grasping near the center of mass and grasping on the side of the acting hand, perhaps to increase visibility of the object.     

The influence of target object shape on maximum grip aperture in human grasping movements

The shape of a target object could influence maximum grip aperture in human grasping movements in several different ways. Maximum grip aperture could be influenced by the required precision of digit placement, by the aim to avoid colliding with the wrong parts of the target objects, by the mass of the target objects, or by (mis)judging the width or the volume of the target objects. To examine the influence of these five factors, we asked subjects to grasp five differently shaped target objects with the same maximal width, height and depth and compared their maximum grip aperture with what one would expect for each of the five factors. The five target objects, a cube, a three-dimensional plus sign, a rectangular block, a cylinder and a sphere, were all grasped with the same final grip aperture. The experimentally observed maximum grip apertures correlated poorly with the maximum grip apertures that were expected on the basis of the required precision, the actual mass, the perceived width and the perceived volume. They correlated much better with the maximum grip apertures that were expected on the basis of avoiding unintended collisions with the target object. We propose that the influence of target object shape on maximum grip aperture might primarily be the result of the need to avoid colliding with the wrong parts of the target object.     

Frontal EEG asymmetry as predictor of physiological responses to aversive memories

Evidence suggests that asymmetry in frontal electrical activity predicts responses to aversive experiences, such that higher left‐sided activity might dampen responses to trauma reminders. We measured frontal asymmetry at rest and during viewing of a trauma film, and assessed startle responses to film‐reminder images. To explore potential moderators, we compared two films (Study 1; N = 64) and modulated reappraisal (Study 2; N = 72). As expected, left frontal activation during film viewing predicted dampened responses in individuals who viewed a staged road accident. However, this effect tended to be reversed when a genocide documentary was used. In Study 2, all participants viewed the genocide film. Left frontal activity at rest again predicted higher startle responses, while reappraisal did not moderate the effects. Thus, the type of trauma film plays a crucial role in the effects of frontal asymmetry, which warrants further critical investigation.     

Current trends and future perspectives of bone substitute materials – From space holders to innovative biomaterials

An autologous bone graft is still the ideal material for the repair of craniofacial defects, but its availability is limited and harvesting can be associated with complications. Bone replacement materials as an alternative have a long history of success. With increasing technological advances the spectrum of grafting materials has broadened to allografts, xenografts, and synthetic materials, providing material specific advantages. A large number of bone-graft substitutes are available including allograft bone preparations such as demineralized bone matrix and calcium-based materials. More and more replacement materials consist of one or more components: an osteoconductive matrix, which supports the ingrowth of new bone; and osteoinductive proteins, which sustain mitogenesis of undifferentiated cells; and osteogenic cells (osteoblasts or osteoblast precursors), which are capable of forming bone in the proper environment. All substitutes can either replace autologous bone or expand an existing amount of autologous bone graft.Because an understanding of the properties of each material enables individual treatment concepts this review presents an overview of the principles of bone replacement, the types of graft materials available, and considers future perspectives. Bone substitutes are undergoing a change from a simple replacement material to an individually created composite biomaterial with osteoinductive properties to enable enhanced defect bridging.     

Epidemiological features and specificities of HCV infection: a hospital-based cohort study in a university medical center of Calabria region

The epidemiological status of HCV in Europe, and in particular in Mediterranean countries, is continuously evolving. The genotype distribution is related to improvement of healthcare conditions, expansion of intravenous drug use and immigration. We review and characterize the epidemiology of the distribution of HCV genotypes within Calabria, an area of Southern Italy. We focus on the pattern of distinct HCV genotype changes over the last 16 years; particularly subtype 1b and genotype 4. We collected data by evaluating a hospital-based cohort of chronic hepatitis C patients; in addition, we report an update including new patients enrolled during last eight months.