Reward and punishment

Minigames capturing the essence of Public Goods experiments show that even in the absence of rationality assumptions, both punishment and reward will fail to bring about prosocial behavior. This result holds in particular for the well-known Ultimatum Game, which emerges as a special case. But reputation can induce fairness and cooperation in populations adapting through learning or imitation. Indeed, the inclusion of reputation effects in the corresponding dynamical models leads to the evolution of economically productive behavior, with agents contributing to the public good and either punishing those who do not or rewarding those who do. Reward and punishment correspond to two types of bifurcation with intriguing complementarity. The analysis suggests that reputation is essential for fostering social behavior among selfish agents, and that it is considerably more effective with punishment than with reward.     

In vitro studies on the effect of delaminated a-C:H film fragments on bone marrow cell cultures

Amorphous hydrogenated carbon (a-C:H) films have many outstanding properties required for a protective coating material on load bearing medical implants. Recently, titanium doped a-C:H films have been evaluated regarding their effects on bone marrow cell cultures. But many materials that are well-tolerated in bulk form are able to induce toxic reaction if present particulate form. In order to further assess biocompatibility aspects of these two coatings, film delamination has been mimicked in exposure to fluids. In the present study, particles from a-C:H, a-C:H/Ti and a-C:H-a-C:H/Ti bilayer films were added to bone marrow cell cultures in vitro. The results showed that plain a-C:H and to a certain extent a-CH/Ti particles were inert. Both kinds of particles did not significantly stimulate the osteoclast-related enzyme tartrate resistant acid phosphatase (TRAP). A slight increase in cell proliferation and total culture TRAP was found in cultures treated by a-C:H-a-C:H/Ti bilayer films. Latter effect can probably be traced back by the relative high percentage of small particles of a size of around 2 microm. However, if corrected by the cell number also no differences between particle-treated and untreated control cultures could be found, indicating the absence of a toxic effect from delaminated a-C:H coatings.     

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.     

Release of vascular plasminogen activator (v-PA) after venous stasis: electrophoretic—zymographic analysis of free and complexed v-PA

To better characterize the plasminogen activators present in the euglobulin fraction (EF) of plasma before and after venous occlusion, euglobulins of 30 healthy volunteers and of 32 patients with idiopathic thromboembolic disease were submitted to SDS-PAGE and zymographic detection. The patterns thus obtained were compared to the fibrinolytic activity (FA) of the EFs measured on fibrin plates. There were significantly more patients with a low fibrinolytic response (FR) to stasis (difference between FA after and before stasis less than or equal to 0.3 TAU/ml) than controls (P less than 0.01). The electrophoretic-zymographic analysis revealed that: (i) in the resting state vascular plasminogen activator (v-PA) is always present in a form exhibiting a mol wt of 110 000 (complex of v-PA with its fast-acting antiactivator); (ii) a high FR to stasis (greater than 1.3 TAU/ml) is always associated with the presence of free v-PA (68 kdalton band); (iii) free v-PA is never detected when the FR is low; and (iv) a poor FR is generally (15 of 17 patients with low FR) associated with apparently complete inhibition of the released v-PA by the fast-acting antiactivator; in the two remaining patients in whom no broadening of the 110 kdalton band is observed, the release mechanism for v-PA is probably impaired.     

Buchbesprechungen

Ohne Zusammenfassung     

Characterization of plasminogen activators from normal human breast and colon and from breast and colon carcinomas

Triton X-100 and NaSCN extracts of 18 normal breast and colon tissues and of 20 breast and colon carcinomas were fractionated by SDS-PAGE and plasminogen activators (PA) revealed by a zymographic method. Four different lysis bands, corresponding to MWs of 54,000, 68,000, 95,000 and 110,000 were observed. Using immunoadsorption with specific antisera against urokinase (UK) and tissue PA (t-PA), we found that all normal tissue extracts contained free t-PA (68 kd). Some of these revealed, in addition, a complex (110 kd) of t-PA with a 40-kd component. The latter presumably represents the fast-acting specific inhibitor of t-PA and UK. Most carcinoma extracts contained, in addition to the two t-PA-related lysis bands, the UK-related 54 kd PA, and some a 95 kd complex of UK with the 40 kd component. For each extractant, mean total fibrinolytic activity of normal and tumor tissue was comparable when measured on conventional fibrin plates, but breast and colon carcinomas contained higher concentrations of UK-related PA. PA activity was higher in normal and carcinoma NaSCN extracts than in the corresponding Triton X-100 extracts. In general, Triton X-100 but not NaSCN extracts of malignant tissue contained a high concentration of fibrinolytic inhibitors. Mixing experiments revealed that the inhibitory activity was mainly directed against UK. It was abolished by acidification of the carcinoma extracts. The anti-UK inhibitory activity was absent in extracts of normal breast or colon and appears to be different from the 40 kd fast-acting PA inhibitor. These studies show that malignant transformation of breast and colon is accompanied by important changes of the production of a UK-related PA and of an inhibitory activity directed against UK.     

Rhythm evokes action: Early processing of metric deviances in expressive music by experts and laymen revealed by ERP source imaging

To examine how musical expertise tunes the brain to subtle metric anomalies in an ecological musical context, we presented piano compositions ending on standard and deviant cadences (endings) to expert pianists and musical laymen, while high‐density EEG was recorded. Temporal expectancies were manipulated by substituting standard “masculine” cadences at metrically strong positions with deviant, metrically unaccented, “feminine” cadences. Experts detected metrically deviant cadences better than laymen. Analyses of event‐related potentials demonstrated that an early P3a‐like component (～ 150–300 ms), elicited by musical closure, was significantly enhanced at frontal and parietal electrodes in response to deviant endings in experts, whereas a reduced response to deviance occurred in laymen. Putative neuronal sources contributing to the modulation of this component were localized in a network of brain regions including bilateral supplementary motor areas, middle and posterior cingulate cortex, precuneus, associative visual areas, as well as in the right amygdala and insula. In all these regions, experts showed enhanced responses to metric deviance. Later effects demonstrated enhanced activations within the same brain network, as well as higher processing speed for experts. These results suggest that early brain responses to metric deviance in experts may rely on motor representations mediated by the supplementary motor area and motor cingulate regions, in addition to areas involved in self‐referential imagery and relevance detection. Such motor representations could play a role in temporal sensory prediction evolved from musical training and suggests that rhythm evokes action more strongly in highly trained instrumentalists. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.     

Biofeedback Training for Partial Weight Bearing in Patients After Total Hip Arthroplasty

Pataky Z, De León Rodriguez D, Golay A, Assal M, Assal J-P, Hauert C-A. Biofeedback training for partial weight bearing in patients after total hip arthroplasty.

Objective

To evaluate a new biofeedback training method based on visual delivery of information in patients after total hip arthroplasty (THA).

Design

Intervention study with prepost design.

Setting

Hospitalized care in a university referral center.

Participants

Patients (N=11) (age 56.1±9.0y) shortly after THA.

Intervention

A mobile system has been used for biofeedback training with the predefined partial weight bearing (PWB) threshold of 20kg. After the learning period, 4 retention tests, consisting of 3 successive walking cycles without feedback, were recorded for each patient: (1) acquisition test, (2) early retention test (after 30min), (3) the day after, and (4) after 2 days.

Main Outcome Measure

The pressure error and the maximum pressure force at each step before and after biofeedback training.

Results

A significant difference of pressure errors between the beginning and the end of the learning period has been measured (42.5±22.5N vs 3.7±11.4N, P<.001). However, there was no difference between the beginning of the learning period and different retention tests (after 30 minutes, after 1 day, after 2 days). In terms of maximal pressure force, there was a difference between the beginning and the end of learning (251N vs 195N, P<.05). The retention tests did not show significant differences compared with the baseline values.

Conclusions

THA patients were able to use the defined PWB during a short period of time and shortly after stopping the training; both the pressure errors and the maximal pressure force attended the values before training. These results confirm the difficulties to achieve PWB in patients after THA.     

Fibrinolysis in normal subjects--comparison between plasminogen activator inhibitor and other components of the fibrinolytic system

We analyzed fibrinolytic parameters in 20 healthy men and 20 healthy women, aged from 25 to 59, before and after 10 and 20 min venous occlusion. The 10 min post-occlusion fibrinolytic activity measured directly in diluted unfractionated plasma by a highly sensitive 125I-fibrin plate assay correlated well with the activity of euglobulins determined by the classical fibrin plate assay (r = 0.729), but pre-stasis activities determined with these two methods did not correlate (r = 0.084). The enhancement of fibrinolytic activity after venous occlusion was mainly due to an increase of t-PA in the occluded vessels (4-fold increase t-PA antigen after 10 min and 8-fold after 20 min venous occlusion). Plasminogen activator inhibitor (PAI) activity and plasminogen activator inhibitor 1 (PAI-1)1 antigen levels at rest showed considerable dispersion ranging from 1.9 to 12.4 U/ml, respectively 6.9 to 77 ng/ml. A significant increase of PAI-1 antigen levels was observed after 10 and 20 min venous occlusion. At rest no correlation was found between PAI activity or PAI-1 antigen levels and the fibrinolytic activity measured by 125I-FPA. However, a high level of PAI-1 at rest was associated with a high prestasis antigen level of t-PA and a low fibrinolytic response after 10 min of venous stasis. Since the fibrinolytic response inversely correlated with PAI activity at rest, we conclude that its degree depends mainly on the presence of free PAI.