Visual behavior of racing bike cyclists in multi-tasking situations

Distracted biking can have serious repercussions for the rider such as accidents. The purpose of the present experiment was to determine the effect of visually monitoring two parameters, the cadence, and the heart rate on a bike computer fixed on a racing bike, and simultaneously detect hazardous traffic situations. Individuals (n = 20) were instructed to ride a racing bike that was fitted onto a roller trainer. After conducting a bicycle step test to assess the maximal heart rate (HFmax), participants were assigned to a within subject-design on a separate day. They were instructed to perform the riding task in two single-task conditions (only watching the traffic at the video with occluded or without occluded bike computer), two multi-tasking conditions (monitoring the cadence of 70 RPM or 90 RPM, monitoring the heart rate, and observing the traffic) and one control condition (no instructions). Percentage dwell time of the eye movements, the constant error from the target cadence, keeping the heart rate in an interval of 50% - 70% of the HFmax, and percentage of the recognized hazard traffic situations were analyzed. The analysis indicated that monitoring the parameters on the bike computer induced no significant decline in perceived hazardous traffic situations.

Inter-limb differences in upper quarter mobility/stability are not associated with performance in competitive swimmers

Background

The Y Balance Test-Upper Quarter (YBT-UQ) is a cost-effective, well-established, closed kinetic chain test to assess inter-limb asymmetries in the upper quarter that could negatively affect swimming performance. Thus, the aim of the present study was to determine YBT-UQ performances and inter-limb differences as well as its association with swimming performance in athletes with diverging levels of expertise.

Methods

Forty female and male competitive swimmers (age range: 10-22 years) with different expertise levels (A-squad: n = 9, B-squad: n = 12, C-squad: n = 19) were tested (reach distances for the YBT-UQ) and swimming performance was calculated using the ratio of individual to world best time.

Results

YBT-UQ performances (i.e., inferolateral reach direction for the dominant arm: p = .027, ηp2 = .12 and the non-dominant arm: p = .031, ηp2 = .17) but not YBT-UQ inter-limb differences significantly differed between groups and were largest in swimmers with the lowest expertise level (i.e., C-squad). Further, YBT-UQ performances (i.e., inferolateral reach direction [r = -.68 to -.70, both p < .05] and composite score [r = -.65 to -.67, both p < .05] for both arms and medial reach direction for the non-dominant arm [r = -.64, p < .05]) but not inter-limb differences were significantly and negatively correlated with swimming performance among B-squad swimmers.

Conclusions

Our results suggest that inter-limb differences in upper quarter mobility/stability are not influenced by the level of expertise and have no significant associations with swimming performance. However, greater reach distances were correlated with lower swimming performance for the B-squad swimmers indicating that a training-related increase in upper quarter mobility/stability could worsen swimming performance in those athletes.

Across-task binding: The development of a representation in learning a continuous movement sequence

Across-task binding is defined as the stimulus/response of one task being linked to the response of another task. The purpose of the present experiment was to determine across-task binding in a continuous movement sequence task with an auditory task of high and low pitch tones and the development of a movement sequence representation. According to the two systems theory of sequence learning, we expected that the developed representation in the across-task binding context relies on the multi-dimensional system rather than on the unidimensional system which is restricted to a set of modules where each module processed information along one task/dimension. An inter-manual transfer design was used to disentangle the sequence representations. The mirror transfer test required the same pattern of muscle activation and joint angles (motor coordinates) in the contralateral limb as experienced during the acquisition phase, while in the non-mirror transfer test, the visual-spatial locations (spatial coordinates) of the target waveform were reinstated. The main finding was that consistently combining visual-spatial positions in a sequence and auditory dimensions such as the tone pitch does not rely on a multidimensional system as predicted by the two-systems theory.

Dyad motor learning in a wrist-robotic environment: Learning together is better than learning alone

OBJECTIVE

Dyad motor practice is characterized by two learners alternating between physical and observational practice, which can lead to better motor outcomes and reduce practice time compared to physical practice alone. Robot-assisted therapy has become an established neurorehabilitation tool but is limited by high therapy cost and access. Implementing dyad practice in robot-assisted rehabilitation has the potential to improve therapeutic outcomes and/or to achieve them faster. This study aims to determine the effects of dyad practice on motor performance in a wrist-robotic environment to evaluate its potential use in robotic rehabilitation settings.

METHODS

Forty-two healthy participants (18-35 years) were randomized into three groups (n = 14): Dyad practice, physical practice with rest and physical practice without rest. Participants practiced a 2 degree-of-freedom gamified wrist movement task for 20 trials using a custom-made wrist robotic device. A motor performance score (MPS) that captured temporal and spatial time-series kinematics was computed at baseline, the end of training and 24 h later to assess retention.

RESULTS

MPS did not differ between groups at baseline. All groups revealed significant performance gains by the end of training. However, dyads outperformed the other groups at the end of training (p < 0.001) and showed higher retention after 24-h (p = 0.02). Median MPS improved by 46.5% in dyads, 25.3% in physical practice-rest, and 33.6% in physical practice-no rest at the end of training compared to baseline.

CONCLUSION

Compared to physical practice alone, dyad practice leads to superior motor outcomes in a robot-assisted motor learning task. Dyads still outperformed their counterparts 24-h after practice.

IMPACT STATEMENT

Improving motor function in complex motor tasks without increasing required practice time, dyad practice can optimize therapeutic resources. This is particularly impactful in robot-assisted rehabilitation regimens as it would help to improve patients' outcomes and increase care efficiency.

Motor Transfer and Proactive Interference in Cycling With a Noncircular Chainring

Athletes must transfer their performance when changing equipment due to innovative developments in sports technology. This kind of transfer has received only moderate attention. The aim of this study was to examine whether a mechanical change in sports equipment disturbs an athlete's performance and affects biomechanical and neurophysiological parameters. Therefore, an experiment was conducted in which 36 participants in three groups pedaled at 70 rounds per minute on a cycling ergometer with a circular and a noncircular (NC) chainring. The dependent variables were the total variability of the cadence, torque effectiveness, and muscle cocontraction (electromyographic cocontraction) of four antagonistic acting muscle pairs. Data were recorded during an acquisition phase, a transfer phase, and a retention phase. The results revealed that practice on a circular chainring induces a positive transfer on the NC chainring for total variability without a proactive interference effect. Torque effectiveness did not change within or between groups during the acquisition, transfer, and retention phases. Torque effectiveness and electromyographic cocontraction were not affected when the chainrings were altered from Day 1 to Day 2. During the retention phase, electromyographic cocontraction was higher when using the NC chainring, but the difference was small in absolute terms. The results regarding transfer and proactive interference seem to be strongly dependent on the movement task and the change in sports equipment. Transfer from the circular to NC chainring indicates refined neuromuscular control and improved movement coordination.

Visual behavior and road traffic hazard situations when using a bike computer on a racing bike: An eye movement study

Bike computers are an important equipment, especially on race bikes where athletes can monitor output parameters. The purpose of the present experiment was to determine the effect of visually monitoring the cadence of a bike computer and to perceive hazard traffic situations in a virtual environment. In a within subject-design individuals (N = 21) were instructed to perform the riding task in two single-task conditions (only watching the traffic at the video with occluded or without occluded bike computer), two dual-task conditions (monitoring the cadence of 70 RPM or 90 RPM and observing the traffic) and one control condition (no instructions). Percentage dwell time of the eye movements, the constant error from the target cadence, and percentage of the recognized hazard traffic situations were analyzed. The analysis indicated that the visual behavior to monitor the traffic was not reduced when individuals used a bike computer to control the cadence.

Associations between upper quarter Y-balance test performance and sport-related injuries in adolescent handball players

Handball players are at a high risk of suffering a sport-related injury. Recent studies in various adult populations (e.g., US Army soldiers/warrior athletes, and military members) showed that poor scores in the upper quarter Y-balance test (YBT-UQ) are related to an increased risk of injury. Yet, it is unclear whether this also applies to adolescent handball players. Thus, the present study aims to determine if pre-season YBT-UQ performance is associated with sport-related injuries during the competitive season in adolescent handball players. One hundred and thirty-three adolescent handball players (age: 15.4 ± 1.7 years; m = 99, f = 42) who competed in the second highest league in the Rhine-Ruhr region, Germany, during the 2021/2022 season participated in the study. Before the competitive season, the players performed the YBT-UQ to assess upper extremity mobility and stability of the throwing and non-throwing arm. Over the 8-month competitive season, the coaches monitored the occurrence of sports-related injuries once a week, using an injury report form from the legal accident insurance. Fifty-seven players (43%) incurred a sport-related injury during the competitive season, of which 27 (47%) had upper body injuries, and 30 (53%) were lower body injuries. The YBT-UQ performance of the throwing and non-throwing arm did not significantly differ between injured and non-injured players. Further, Cox proportional hazard survival regression model analyses revealed that only the presence of an inferolateral reach asymmetry score ≥7.75% arm length was associated with a moderate increase in the risk (hazard ratio = 2.18, 95% confidence interval = 1.02–4.68, p = 0.045) of lower but not upper or whole-body injuries. Our findings suggest that the YBT-UQ has limited value as a field-based screening tool to assess the risk of sport-related injuries in adolescent handball players.

Effects of age simulation and age on motor sequence learning: Interaction of age-related cognitive and motor decline

Aging is known to lead to decrements in sensory and cognitive functioning and motor performance. The purpose of the present experiment was twofold: a) We assessed the influence of wearing an age simulation suit on motor sequence learning, cognitive speed tasks and far visual acuity in healthy, younger adults. b) We evaluated the interaction of cognitive aging and declining motor sequence learning in older adults. In a between-subjects design we tested 11 younger adults (M_age = 23.6 years) without the age suit, 12 younger adults wearing the age suit (M_age = 23.2 years), and 23 older adults (M_age = 72.6 years). All participants learned a simple, spatial-temporal movement sequence on two consecutive days, and we assessed perceptual processing speed (Digit Symbol Substitution test and Figural Speed test) and far visual acuity. Wearing an age simulation suit neither affected the learning of the simple motor sequence nor the performance at the cognitive speed tasks in younger adults. However, far visual acuity suffered from wearing the suit. Younger adults with and without the suit showed better motor sequence learning compared to older adults. The significant correlations between the cognitive speed tests and the motor learning performance in older adults indicated that cognitive aging partially explains some of the variance in age-related motor learning deficits.

Attentional Demand of a Movement Sequence Guided by Visual-Spatial and by Motor Representations

The objective of the experiment was to assess the change in attentional demands of a movement sequence guided by visual-spatial and motor representations across practice sessions in a dual-task probe paradigm. Participants were randomly assigned to either a 1-day or 2-day practice group. Following acquisition of the motor sequence task, participants first conducted a retention test and then four inter-manual transfer tests under single and dual-task conditions. The probe task was a simple reaction time. The inter-manual transfer tests, consisting of a mirror and non-mirror test, examined the development of the motor and visual-spatial representation, respectively. The results indicated that both representations guided the movement sequence and required attention. The attentional demands did not change with additional practice.

Side differences of upper quarter Y balance test performance in sub-elite young male and female handball players with different ages

Background

Handball is characterised by repetitive passing and shooting actions mainly performed with the throwing arm. This can lead to side differences (inter-limb asymmetry) in upper quarter mobility/stability between the throwing and non-throwing arm, which could even increase with advancing age (i.e., playing experience). However, side differences in upper quarter mobility/stability is associated with an increased musculoskeletal injury risk. Therefore, we assessed side differences in upper quarter mobility/stability in young handball players at different ages using a cross-sectional study design.

Methods

Upper Quarter Y Balance test performance of the throwing and non-throwing arm was assessed in 190 sub-elite young female and male handball players (13–18 years). Per arm, relative maximal reach distances (% arm length) for all three directions (i.e., medial, inferolateral, superolateral) and the composite score (CS) were calculated and used for an age × side analysis of variance. Additionally, partial eta-squared (ηp²) was calculated as an effect size measure.

Results

Irrespective of measure, statistically significant main effects of age (except for the composite score) and side but no statistically significant age × side interaction effects were detected. Further, limb asymmetry in the inferolateral reach direction was above the injury-related cut-off value (i.e., ≥ 7.75% arm length) in 13- and 14-year-olds but not in the older players.

Conclusion

The detection of limb asymmetry above the proposed injury-related cut-off value in younger players (13- and 14-year-olds) but not in older players (15- to 18-year-olds) may be indicative for an increased injury risk for the younger age group. Thus, prevention programs should be implemented in the handball training routine, especially for the younger ones.

Acute effects of a single unilateral balance training session on ipsi- and contralateral balance performance in healthy young adults

Objective

While there is evidence on the short-term effects of unilateral balance training (BT) on bipedal balance performance, less is known on the acute effects of unilateral BT on unilateral (i.e., ipsi- and contralateral) balance performance. Thus, the present study examined the acute effects of a single unilateral BT session conducted with the non-dominant, left leg or the dominant, right leg on ipsilateral (i.e. retention) and contralateral (i.e., inter-limb transfer) balance performance in healthy young adults (N = 28).

Results

Irrespective of practice condition, significant improvements (p < 0.001, d = 1.27) in balance performance following a single session of unilateral BT were observed for both legs. Further, significant performance differences at the pretest (p = 0.002, d = 0.44) to the detriment of the non-dominant, left leg diminished immediately and 30 min after the single unilateral BT session but occurred again 24 h following training (p = 0.030, d = 0.36). These findings indicate that a single session of unilateral BT is effective to reduced side-to-side differences in balance performance, but this impact is only temporary.

Bimanual coordination associated with left- and right-hand dominance: testing the limb assignment and limb dominance hypothesis

In an experiment conducted by Kennedy et al. (Exp Brain Res 233:181–195, 2016), dominant right-handed individuals were required to produce a rhythm of isometric forces in a 2:1 or 1:2 bimanual coordination pattern. In the 2:1 pattern, the left limb performed the faster rhythm, while in the 1:2 pattern, the right limb produced the faster pattern. In the 1:2 pattern, interference occurred in the limb which had to produce the slower rhythm of forces. However, in the 2:1 condition, interference occurred in both limbs. The conclusion was that interference was not only influenced by movement frequency, but also influenced by limb dominance. The present experiment was designed to replicate these findings in dynamic bimanual 1:2 and 2:1 tasks where performers had to move one wrist faster than the other, and to determine the influence of limb dominance. Dominant left-handed (N = 10; LQ = − 89.81) and dominant right-handed (N = 14; LQ = 91.25) participants were required to perform a 2:1 and a 1:2 coordination pattern using Lissajous feedback. The harmonicity value was calculated to quantify the interference in the trial-time series. The analysis demonstrated that regardless of limb dominance, harmonicity was always lower in the slower moving limb than in the faster moving limb. The present results indicated that for dominant left- and dominant right-handers the faster moving limb influenced the slower moving limb. This is in accordance with the assumption that movement frequency has a higher impact on limb control in bimanual 2:1 and 1:2 coordination tasks than handedness.

Cardiac remodeling in ambitious endurance-trained amateur athletes older than 50 years

Background

Data on cardiac remodeling in athletes are conflicting and rarely available in veteran athletes.

Purpose

Therefore, in this study we aimed to define echocardiographic features of healthy endurance athletes older than 50 years.

Methods

We included probands aged &gt;50 years, who have performed endurance sports at 70% of their maximum heart rate for at least 1 hour 3 times per week over the previous 5 years.

Results

Between November 2018 and May 2019, 69 probands were recruited. Median age was 57 years (IQR 52–64) and 26% were female. Groups were formed according to the median training time of 6 hours per week: (A) 45 probands with ≥6 hours (IQR 6–10) and (B) 24 probands with &lt;6 hours (IQR 3.5–5). Age, sex and body mass index were similar. Group A demonstrated slightly smaller right atrial and left atrial (LA) diameters when compared to probands in B (53mm (IQR 49–55) vs. 53mm (IQR 51–58), p=0.045, and 52mm (IQR 49–55) vs. 53mm (IQR 52–58), p=0.039, respectively) and showed preserved diastolic function (p=0.026) with lower E/E' ratio (7 (IQR 6–9) vs. 9 (IQR 7–10), p=0.039). Interventricular septal thickness and relative wall thickness ratio were similar.

Global right and left ventricular (LV) strain were similar, but LA reservoir strain was higher in group A than in B (27% (IQR 22–34) vs. 20% (IQR 15–29), p=0.016).

Conclusion

Endurance training in healthy athletes older than 50 years does not result in relevant chamber dilatation or LV hypertrophy and a weekly training duration of ≥6 hours seems beneficial to preserve diastolic function associated with an increased LA reservoir function.

Funding Acknowledgement

Type of funding source: None

Dyad training protocols and the development of a motor sequence representation

The purpose of the experiment was to determine the extent to which observation and the inter-trial dialogue in a dyad training protocol enhance the development of a movement sequence representation. The task was to reproduce a 1300ms spatial-temporal pattern of elbow extension/flexion movements. An inter-manual transfer design with a retention test and two effector transfer tests was used. The mirror transfer test required the same motor pattern of homologous muscle activation and a sequence of joint angles as experienced during the acquisition phase, and the non-mirror transfer test required the same visual-spatial pattern as practiced during acquisition. Participants (N=40) were randomly assigned to one of four groups (50 practice acquisition trials): a dyad training group where two participants alternated between physical and observational practice and permitting an inter-trial dialogue, a dyad training group where two participants alternated between physical practice and permitting a dialogue without observation, a dyad training group where two participants alternated between physical and observational practice without a dialogue, and an individual practice control group where one participant learned the movement sequence. The practice duration was for all participants identical. The results indicated that participants involved in the dyad training protocols with either observation and/or the inter-trial dialogue developed a motor representation of the movement sequence.

The Cognitive Status of Older Adults: Do Reduced Time Constraints Enhance Sequence Learning?

Research has indicated that older adults perform movement sequences more slowly than young adults. The purpose of the present experiment was to compare movement sequence learning in young and older adults when the time to perform the sequence was extended, and how the elderly's cognitive status (Montreal Cognitive Assessment [MoCA]) interacted with sequence learning. The task was to minimize the difference between a target sequence pattern and the sequence produced by elbow extension-flexion movements. On Day 1, participants (28 young adults; 28 older adults) practiced the sequence under two time windows: 1300 ms or 2000 ms. On Day 2, retention performance and the cognitive status were assessed. The results demonstrated that young adults performed superior compared to older adults. Additional time to perform the sequence did not improve retention performance for the older adults. The correlation between the error score and the MoCA score of r = -.38 (p < .05) in older adults indicated that a better cognitive status was associated with performance advantages in sequence learning.

More Than Hitting the Correct Key Quickly

Many studies have documented that multitasking reduces Response Time (RT) indicators of implicit sequence learning as well as the expression of acquired sequence knowledge in RT benefits. In these tasks it is only relevant that the correct key is hit quickly, not where it is hit. We explored how variability in response location is influenced by (a) breaking a repeating sequence of target locations, (b) multitasking demands in the current trial, and (c) presence of multitasking in the block. Participants performed a Serial Reaction Time Task (SRTT) on a touchscreen while shutting down a beep tone by pressing the space bar with their non-dominant hand (throughout Experiment 1 and in the second half of Experiment 2). The first-order sequence of four response locations on the screen was broken by off-sequence deviants in 1/6th of the trials. Our results show a dissociation between RT and response location variability. While the effect of breaking the sequence on RT was larger under single- than under multitasking, breaking the sequence only led to an increase in response location variability under multitasking. Experiment 3 suggested that the impact of sequence knowledge on either aspect of performance in the SRTT is limited by interference from an additional task.

Limb Differences in Unipedal Balance Performance in Young Male Soccer Players with Different Ages

In soccer, the dominant leg is frequently used for passing and kicking while standing on the non-dominant leg. Consequently, postural control in the standing leg might be superior compared to the kicking leg and is further enhanced with increasing age (i.e., level of playing experience). Unfortunately, leg differences in postural control are associated with an increased risk of injuries. Thus, we examined differences between limbs in unipedal balance performance in young soccer players at different ages. Performance in the Lower Quarter Y Balance Test (YBT-LQ) of the dominant and non-dominant leg and anthropometry was assessed in 76 young male soccer players (under-13 years [U13]: n = 19, U15: n = 14, U17: n = 21, U19: n = 22). Maximal reach distances (% leg length) and the composite scores were used for further analyses. Statistical analyses yielded no statistically significant main effects of leg or significant Leg × Age interactions, irrespective of the measure investigated. However, limb differences in the anterior reach direction were above the proposed cut-off value of >4 cm, which is indicative of increased injury risk. Further, statistically significant main effects of age were found for all investigated parameters, indicating larger reach distances in older (U19) compared to younger (U13) players (except for U15 players). Although reach differences between legs were non-significant, the value in the anterior reach direction was higher than the cut-off value of >4 cm in all age groups. This is indicative of an increased injury risk, and thus injury prevention programs should be part of the training of young soccer players.

Training Motor Sequences: Effects of Speed and Accuracy Instructions

Participants practiced a fixed 3- and a fixed 6-key press sequence for 144 times each. In the speed group, they were instructed to execute their sequences fast without bothering much about errors while the accurate group was instructed to be careful and prevent errors. In the test phase, participants executed series of 3 and 6 responses (a) when all element-specific stimuli were displayed in the familiar order, (b) in response to just the familiar first stimulus, and (c) by responding to random stimuli. The speed instruction yielded stronger sequencing skill while the accuracy instruction developed stronger reaction skill.

Monitoring anticoagulation of primary haemostasis

This article provides an overview on current commercially available methods to determine primary haemostasis as a target of drug-mediated anticoagulation. It focuses on whole blood methods only, and references the currently major achievements that have been reported with each method in respect to its clinical use. Advantages and disadvantages of the various methods are presented, based on considerations of platelet physiology, and on feasibility of the procedures.

High proportion of patients with bleeding of unknown cause in persons with a mild-to-moderate bleeding tendency: Results from the Vienna Bleeding Biobank (VIBB)

INTRODUCTION

Data on clinical characteristics and the prevalence of underlying coagulopathies in patients with mild-to-moderate bleeding disorders (MBDs) are scarce.

AIM

We established the Vienna Bleeding Biobank (VIBB) to characterize and thoroughly investigate Austrian patients with MBDs.

RESULTS

Four hundred eighteen patients (female = 345, 82.5%) were included. A platelet function defect (PFD) was diagnosed in 26 (6.2%) and a possible PFD in 30 (7.2%) patients. Eight patients (1.9%) were diagnosed with von Willebrand disease (VWD) (type 1 n = 6; type 2 n = 2), and 29 patients had low VWF (30-50 IU/dL). Deficiencies in factor VIII, IX, XI or XIII were found in 11 (2.6%), 3 (0.7%), 3 (0.7%) and 1 patient(s), 2 patients had dysfibrinogenaemia, and further 2 had possible PFD and FXI deficiency. Probable causal mutations were detected in 8 of 11 patients with FVIII deficiency, 2 of 3 patients with FIX deficiency and 2 of 8 patients with VWD. Three hundred three patients (72.5%) had normal results in the coagulation assays and were categorized as patients with bleeding of unknown cause (BUC). The bleeding score did not differ between patients with and without established diagnosis. A diagnosis of a bleeding disorder was more frequently made in men than in women (49.3% vs 22.9%). Male sex (OR 3.55, 95% CI: 2.02-6.22; P < .001) and blood group 0 (OR 1.86, 95% CI: 1.17-2.94; P = .008) were independently associated with diagnosis of a bleeding disorder.

CONCLUSION

The high rate of patients with BUC despite in-depth haemostatic assessment underlines the incompleteness of available routine laboratory tests. Males with MBDs were more likely to be diagnosed with an established bleeding disorder than females.

The influence of eye-movements on the development of a movement sequence representation during observational and physical practice

An experiment was conducted to examine the development of a movement sequence representation and the role of eye-movements during observational and physical practice. The task was to reproduce a 1300ms spatial-temporal pattern of a sequence of elbow flexions and extensions. An inter-manual transfer design with a retention and two effector transfer tests (contralateral limb) was used. The mirror transfer test required the same pattern of homologous muscle activation and a sequence of joint angles as experienced during the acquisition phase, and the non-mirror transfer test required the same visual-spatial pattern as performed or observed during acquisition. Participants were randomly assigned to one of four groups differing in eye-movements (free to use their eyes vs. instruction to fixate) and the practice type (observational practice vs. physical practice). The results indicated that permitting to use eye-movements facilitates sequence learning. This advantage was found on both practice types. The results of the transfer tests indicated that participants of the physical practice group who were permitted to use their eyes demonstrated superior transfer performance in the mirror transfer test, while participants in the observational practice group demonstrated better performance on the non-mirror transfer test. These findings indicated that eye-movements enhanced the development of a visual-spatial representation during observational practice as well as a motor representation during physical practice.

The simplest acquisition protocol is sometimes the best protocol: performing and learning a 1:2 bimanual coordination task

An experiment was conducted to determine if the performance and learning of a multi-frequency (1:2) coordination pattern between the limbs are enhanced when a model is provided prior to each acquisition trial. Research has indicated very effective performance of a wide variety of bimanual coordination tasks when Lissajous plots with goal templates are provided, but this research has also found that participants become dependent on this information and perform quite poorly when it is withdrawn. The present experiment was designed to test three forms of modeling (Lissajous with template, Lissajous without template, and limb model), but in each situations, the model was presented prior to practice and not available during the performance of the task. This was done to decrease dependency on the model and increase the development of an internal reference of correctness that could be applied on test trials. A control condition was also collected, where a metronome was used to guide the movement. Following less than 7 min of practice, participants in the three modeling conditions performed the first test block very effectively; however, performance of the control condition was quite poor. Note that Test 1 was performed under the same conditions as used during acquisition. Test 2 was conducted with no augmented information provided prior to or during the performance of the task. Only participants in the limb model condition were able to maintain performance on Test 2. The findings suggest that a very simple intuitive display can provide the necessary information to form an effective internal representation of the coordination pattern which can be used guide performance when the augmented display is withdrawn.

Intentional Switching Between Bimanual Coordination Patterns

Previous theoretical and empirical work indicates that intentional changes in a bimanual coordination pattern depends on the stability of the bimanual coordination pattern (Kelso, Schotz, & Schöner, 1988; Scholz & Kelso, 1990). The present experiments retest this notion when online Lissajous displays are provided. Switching to and from in-phase and antiphase and to and from 90° and 270° were tested in Experiment 1. Participants were able to very effectively produce the 180°, 90°, and 270° coordination patterns although performance of the in-phase coordination task was even more stable. The data indicated that switching to in-phase from antiphase was more rapid than vice versa and that switching times between 90° to 270° were similar. Experiment 2 investigated switching between 1:2 and 2:1 bimanual coordination patterns. The results indicated that switching time was similar between the 2:1 and 1:2 coordination tasks and that increases in stability over practice resulted in additional decreases in switching times. This provides additional evidence that the attractor landscape is fundamentally different dependent on the type of information provided the performer. What remains to be done is to reconcile these results with the various theories/perspectives currently used to describe and explain bimanual coordination.

Platelet activation in the presence of neutral protamine Hagedorn insulin: a new feature of antibodies against protamine/heparin complexes

Essentials Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin. The interaction between NPH-insulin, anti-PRT/heparin antibodies and platelets was investigated. Anti-PRT/heparin antibodies activate platelets in presence of NPH-insulin dependent on heparin. Cross-reactivity seems to have no major effect on the clinical outcome of medical patients.

SUMMARY

Background Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin, a commonly used therapeutic agent for diabetes mellitus. Immunization against PRT/heparin complexes is common in diabetic patients. Objectives To investigate the impact of NPH-insulin on the interaction between anti-PRT/heparin antibodies and platelets. Methods The interaction between NPH-insulin and anti-PRT/heparin antibodies was tested using in-house enzyme immunoassays. The ability of anti-PRT/heparin antibodies to activate platelets in the presence of NPH-insulin (and heparin) was investigated using flow cytometry. Results Twenty-one out of 80 sera containing anti-PRT/heparin IgG showed binding to NPH-insulin. Anti-PRT/heparin IgG from immunized patients bound to platelets in the presence of NPH-insulin, but not in the presence of native insulin. Anti-PRT/heparin antibodies induced P-selectin expression in the presence of NPH-insulin in a heparin-dependent way (median mean fluorescence intensity in the presence of NPH-insulin: 55, 95% confidence interval [CI] 18.7-100.5 vs. NPH-insulin and heparin: 204, 95% CI 106.5-372.8). The clinical relevance of platelet-activating anti-PRT/heparin antibodies was assessed by investigating a multicenter study cohort of 332 acutely ill medical patients who received heparin. None of the 21 patients with anti-PRT/heparin IgG developed thrombocytopenia or thromboembolic complications. Conclusions Anti-PRT/heparin antibodies activate platelets in the presence of NPH-insulin in a heparin-dependent way. However, results from our preliminary study indicate no major impact of these antibodies on the clinical outcome in medical patients receiving heparin, particularly on thromboembolic complications.

Hemispheric asymmetries of a motor memory in a recognition test after learning a movement sequence

Two experiments utilizing a spatial-temporal movement sequence were designed to determine if the memory of the sequence is lateralized in the left or right hemisphere. In Experiment 1, dominant right-handers were randomly assigned to one of two acquisition groups: a left-hand starter and a right-hand starter group. After an acquisition phase, reaction time (RT) was measured in a recognition test by providing the learned sequential pattern in the left or right visual half-field for 150ms. In a retention test and two transfer tests the dominant coordinate system for sequence production was evaluated. In Experiment 2 dominant left-handers and dominant right-handers had to acquire the sequence with their dominant limb. The results of Experiment 1 indicated that RT was significantly shorter when the acquired sequence was provided in the right visual field during the recognition test. The same results occurred in Experiment 2 for dominant right-handers and left-handers. These results indicated a right visual field left hemisphere advantage in the recognition test for the practiced stimulus for dominant left and right-handers, when the task was practiced with the dominant limb.

Life span changes: Performing a continuous 1:2 bimanual coordination task

The experiment was conducted to determine the influence of mirror movements in bimanual coordination during life span. Children, young adults, and older adults were instructed to perform a continuous 1:2 bimanual coordination task by performing flexion-extension wrist movements over 30s where symmetrical and non-symmetrical coordination patterns alternate throughout the trial. The vision of the wrists was covered and Lissajous-feedback was provided online. All age groups had to perform 10 trials under three different load conditions (0kg, .5kg, 1.0kg: order counterbalanced). Load was manipulated to determine if increased load increases the likelihood of mirror movements. The data indicated that the performance of the young adults was superior compared to the children and older adults. Children and older adults showed a stronger tendency to develop mirror movements and had particular difficulty in performing the non-symmetrical mode. This type of influence may be attributed to neural crosstalk.

Specificities of Platelet Autoantibodies and Platelet Activation in Lupus Anticoagulant Patients: A Relation to their History of Thromboembolic Disease

Lupus anticoagulants (LA) prolong in vitro phospholipid-dependent coagulation tests, but are associated with thromboembolic disease (TE). However, a subgroup of individuals with LA has no TE, and it is therefore desirable to distinguish those at risk for TE from those without. Whether platelets have a primary role in the development of TE is not clear yet. We determined platelet autoantibodies to identify a specific platelet target which is associated with platelet activation in 97 patients with a long history of detectable LA, 65 patients with TE (LA/TE+), and 32 individuals without TE (LA/TE+). Thrombocytopenia was more common in the LA/TE- than in the LA/TE+ group ( P &lt; 0.05). Both groups had platelet antibodies, but the frequency of antibodies was lower in LA/TE+ than LA/TE- patients ( P &lt; 0.01), who had higher antibody titres against glycoprotein IIb/IIIa and glycoprotein Ib/IX ( P &lt; 0.05). Also, their platelets were more activated, as determined by PAC-1 binding ( P &lt; 0.01). These differences were also noted if patients with arterial thrombosis were evaluated separately. These findings in LA/TE- individuals were similar to those in patients with chronic autoimmune thrombocytopenia. However, there was no autoantibody target identifiable to distinguish between LA/TE- from LA-TE+ individuals. We therefore conclude that the presence of platelet antibodies, even if associated with platelet activation, is not sufficient to dispose LA patients to thromboembolic disease.

PO-63 - Exhausted platelets in cancer patients with high risk of venous thromboembolism and poor prognosis

INTRODUCTION

Platelets play a crucial role in cancer development, progression and metastatic spread of malignancy. In vitro data show that cancer cells have the ability to activate platelets, and clinical studies found increased levels of platelet activation markers in cancer patients. Moreover, platelets are thought to be involved in the development of venous thromboembolism (VTE) in cancer patients, a frequent complication of malignant disease associated with high morbidity and mortality.

AIM

In this study, we aimed to examine the activation status of platelets in cancer patients and investigate the association with risk of future venous thromboembolism (VTE) and mortality.

MATERIALS AND METHODS

In a prospective observational cohort study of cancer patients we measured pre-chemotherapy platelet P-selectin and glycoprotein (GP) IIb/IIIa expression and monocyte-platelet aggregates (MPA) in vivo and in response to ex vivo stimulation of the platelet activation receptors protease-activated receptor (PAR) -1, -4, and GPVI by whole blood flow cytometry. Primary and secondary endpoints of the study were occurrence of objectively confirmed VTE and death during 2-year follow-up, respectively.

RESULTS

Out of 62 patients (median age [interquartile range, IQR]: 63 [54-70] years, 48% female) with cancers of the pancreas (n=19), lung (n=18), brain (n=14), colon (n=8) and stomach (n=3), 9 (14.5%) developed VTE and 32 (51.6%) died. P-selectin, activated GPIIb/IIIa expression and MPA formation did not significantly differ between tumor sites (Kruskal Wallis test). Reduced platelet responsiveness to PAR-1 and GPVI stimulation was associated with a higher risk of VTE (hazard ratio [HR] per decile increase in %P-selectin positive platelets: 0.73 [95% confidence interval: 0.56-0.92, p=0.007] and 0.77 [0.59-0.98, p=0.034], respectively; Table 1). Further, lower platelet P-selectin and activated GPIIb/IIIa expression in vivo and in response to PAR-1, -4 and GPVI stimulation, but not MPA formation, were associated with a higher risk of death (Table 1).

CONCLUSIONS

Cancer patients with a poor prognosis had degranulated platelets, presumably as a consequence of previous activation. Our data suggest that platelets' continuous activation and thus exhaustion is involved in cancer-associated VTE and cancer mortality.

Magnifying visual target information and the role of eye movements in motor sequence learning

An experiment investigated the influence of eye movements on learning a simple motor sequence task when the visual display was magnified. The task was to reproduce a 1300 ms spatial-temporal pattern of elbow flexions and extensions. The spatial-temporal pattern was displayed in front of the participants. Participants were randomly assigned to four groups differing on eye movements (free to use their eyes/instructed to fixate) and the visual display (small/magnified). All participants had to perform a pre-test, an acquisition phase, a delayed retention test, and a transfer test. The results indicated that participants in each practice condition increased their performance during acquisition. The participants who were permitted to use their eyes in the magnified visual display outperformed those who were instructed to fixate on the magnified visual display. When a small visual display was used, the instruction to fixate induced no performance decrements compared to participants who were permitted to use their eyes during acquisition. The findings demonstrated that a spatial-temporal pattern can be learned without eye movements, but being permitting to use eye movements facilitates the response production when the visual angle is increased.

Detection of granulocyte-reactive antibodies: a comparison of different methods

BACKGROUND AND OBJECTIVES

Granulocyte-reactive antibodies can cause autoimmune and neonatal immune neutropenias as well as transfusion-related acute lung injury. The classical antibody-detection methods granulocyte aggregation test (GAT), granulocyte immunofluorescence test (GIFT) and monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) are time-consuming and technically challenging. In recent years, flow cytometric white blood cell immunofluorescence test (Flow-WIFT) and the microbeads assay LabScreen® Multi have emerged and are still subject of evaluation. These serological tests were compared on a screening and specification level.

MATERIALS AND METHODS

For screening, the combination of GAT/GIFT was compared to Flow-WIFT testing 333 samples. Positive samples were further analysed with MAIGA and LabScreen® Multi.

RESULTS

Granulocyte aggregation test/GIFT detected 77 positive samples, Flow-WIFT found 108 granulocyte-reactive samples. Six Samples were only positive in GAT/GIFT, and 37 samples were only positive in Flow-WIFT (κ = 0.682). Antibody specification with MAIGA and the microbeads assay confirmed granulocyte-reactivity in 83 cases with 70 matching results (κ = 0.742). However, out of six detected human neutrophil antigen (HNA) reactivities only two specificities matched in both assays.

CONCLUSION

Flow-WIFT may be a valuable addition to GIFT for granulocyte-reactive antibody screening. MAIGA remains the most reliable laboratory method for antibody specification.

Röntgenstrukturanalyse von zwei Verbindungen des Kupfertyps BaMLn2O5 (M = Zn, Ln = Sm, Tm) und von BaSmAIZn3O7 / X-Ray Analysis of Two Compounds of the Copper Type BaMLn2O5 (M=Zn, Ln=Sm, Tm) and of BaSmAlZn3O7

Kupfertyps BaMLn2O5 (M=Zn, Ln=Sm, Tm) und von BaSmAIZn3O7 X-Ray Analysis of Two Compounds of the Copper Type BaMLn2O5 (M=Zn, Ln=Sm, Tm) and of BaSmAlZn3O7 The barium zinc lanthanoide oxides BaZnSm2O5 (I) and BaZnTm2O5 (II) crystallize in the BaCuLn2O3 copper type with orthorhombic symmetry, space group D16 2h,Pnma, (I)

a = 12.575(2), b = 5.804(1), c = 7.198(1) Å and (II):

a = 12.258(2), b = 5.684(1), c = 7.010(2) Å, Z = 4. Zinc shows square pyramidal oxygen coordina­ tion, but the strong elongation of the CuO5 pyramid in the copper type is missing. BaSmAlZn3O7 crystallizes in the space group C4 6V-P63mc, a = 6.346(1), c = 10.237(3) Å, Z = 2. The metal coordination of oxygen and the shifts of the ratio Al : Zn at the sites (6c) and (2a) depending on the size of the lanthanoid ions are discussed.

Granulocyte-reactive antibodies are associated with red blood cell alloimmunization

Granulocyte-reactive antibodies may cause transfusion-related acute lung injury (TRALI) and immune neutropenias. Risk factors for their acquisition other than previous alloexposition are largely unknown. In addition to the known association between human leucocyte antigen alloantibodies and red blood cell alloimmunization in selected cohorts of transfused patients, this study investigated a possible extension of this association to granulocyte-reactive antibodies in women with a history of pregnancy. The overall prevalence of granulocyte-reactive antibodies in 333 samples from women with a history of pregnancy (143 samples containing red cell alloantibodies) was 23·1%. The prevalence in the red cell-alloimmunized group (32·9%) was significantly higher than in controls (15·8%, P < 0·001). This could suggest that some individuals may be strong immunological responders, forming alloantibodies more readily than others.

Interlimb practice and aging: coding a simple movement sequence

BACKGROUND/STUDY CONTEXT: The purpose was to determine if aging interacts with the coding of a simple spatial-temporal movement sequence.

METHODS

An interlimb practice paradigm (24 participants; 12 young adults [age: 23-29]; 12 old adults [age: 65-78]) was designed to determine the coordinate system (visual-spatial/motor) that is used to code the movement sequence. Practice was scheduled over 2 days involving either the same visual-spatial or the same motor coordinates. On Day 3, two retention tests (Day 1/Day 2) were conducted.

RESULTS

Keeping the motor coordinates the same during acquisition resulted in superior retention only for younger adults.

CONCLUSION

The data provide strong evidence that the motor code plays a dominant role in acquiring simple movement sequences for younger adults, but not for older adults.