The effect of plasma removal from apheresis platelet concentrates on platelet function

The effect of plasma removal on platelet function has scarcely been investigated. Plasma removal from apheresis platelet concentrates was achieved by centrifugation at 5000 g for 6 min or 2000 g for 10 min. After resting for 1 h, platelet concentrates were resuspended in 0·9% NaCl. Platelet function was tested before centrifugation and after resuspension by multiple electrode impedance aggregometry (MEA) and light transmission aggregometry (LTA). Plasma removal resulted in 10-14% lower response to TRAP-6 by MEA using both washing procedures, whereas TRAP-6-inducible aggregation by LTA increased slightly (2-5%). Neither plasma removal method affected collagen-induced aggregation. Thus, platelet function did not deteriorate significantly by either method.

The anatomical collection of Giovan Battista Rini (1795-1856): A paleoradiological investigation

Eight anatomical preparations from the collection of Giovan Battista Rini (1795-1856) at the Desenzano Hospital Pathology Division (Brescia, Italy) were examined by computed tomography (CT). The aim of the study was to obtain detailed information on the state of preservation of these "anatomical mummies" and the techniques used to prepare them. Relying on the existing literature, the examined specimens (five heads with necks, two busts and one heart) could be divided into three types of anatomical specimens: "dry preparations," "corrosion preparations," and "organ preparations." CT examination enabled the assessment of the exact features of each specimen, some of the preparation techniques applied, the presence of foreign bodies, and the use of substances to fill the blood vessels. All of the cases demonstrated an extremely good state of preservation. The study sheds new light on important-yet scarcely known-preparation techniques created for different anatomical demonstrations. Results of the CT investigation were consistent with the anatomical preservation methods described in 18th to 20th century literature, particularly those of Italy.

Practice makes transfer of motor skills imperfect

We investigated the practice-effects on motor skill transfer and the associated representational memory changes that occur during the within-practice and between-practice phases. In two experiments, participants produced extension-flexion movements with their dominant right arm for a limited or prolonged practice session arranged in either a single- or multi-session format. We tested the ability of participants to transfer the original pattern (extrinsic transformation) or the mirrored one (intrinsic transformation) to the non-dominant left arm, 10 min and 24 h after the practice sessions. Results showed that practice induces rapid motor skill improvements that are non-transferable irrespective of the amount of acquisition trials. Furthermore, the extrinsic component of the skill develops early and remains the dominant coding system during practice. Conversely, we found distinct between-practice memory changes: a limited practice induces an off-line development of the extrinsic component, whereas a prolonged practice session subserves the off-line development of the intrinsic component (experiment 2). We provided further evidence that the long-term representation of the motor skill also depends on the nature of the practice session itself: the parsing of practice into multiple sessions narrows the effector-transfer capacities in comparison to a single session (experiment 1). These findings yield theoretical and practical implications that are discussed in the context of recent motor skill learning models.

The coding and inter-manual transfer of movement sequences

The manuscript reviews recent experiments that use inter-manual transfer and inter-manual practice paradigms to determine the coordinate system (visual-spatial or motor) used in the coding of movement sequences during physical and observational practice. The results indicated that multi-element movement sequences are more effectively coded in visual-spatial coordinates even following extended practice, while very early in practice movement sequences with only a few movement elements and relatively short durations are coded in motor coordinates. Likewise, inter-manual practice of relatively simple movement sequences show benefits of right and left limb practice that involves the same motor coordinates while the opposite is true for more complex sequences. The results suggest that the coordinate system used to code the sequence information is linked to both the task characteristics and the control processes used to produce the sequence. These findings have the potential to greatly enhance our understanding of why in some conditions participants following practice with one limb or observation of one limb practice can effectively perform the task with the contralateral limb while in other (often similar) conditions cannot.

Methods for testing platelet function for transfusion medicine

BACKGROUND

Currently only indirect measures are required for monitoring the function of platelets in platelet concentrates (PC).

METHODS

This is an overview on currently available commercialized methods that have been used to determine platelet function in donors, concentrates and after transfusion. We show examples for the application of the no/low shear methods light-transmission aggregometry, flow cytometry, multiple electrode aggregometry, thrombelastography and dynamic light scattering, and those applying high shear, the platelet function analyzer-100, and the cone and plate analyzer. Advantages and disadvantages of the various methods to screen donors, evaluate the haemostatic properties maintained in the PC and after transfusion are discussed, based on considerations of platelet physiology, and the feasibility of the various procedures. This survey focuses on reports from the last 10 years, as the technology for the production of PCs has advanced significantly during the last few years.

CONCLUSION

Specific aspects of platelet function can be assessed by the no/low shear methods, while the high shear methods provide more general analysis of platelet haemostatic competence. Yet, there is no strong evidence that the in vitro data correspond with the clinical outcome.

Age-related effects in interlimb practice on coding complex movement sequences

Hikosaka et al. (1999) proposed that sequential movements are acquired in independent visual-spatial and motor coordinate systems with coding initially represented in visual-spatial coordinates, and later after extended practice in motor coordinates. One aspect of sequence learning that has not been systematically studied, however, is the question of whether or not older adults show the same pattern of coding in inter-limb practice as younger learners. In the present experiment an inter-limb practice paradigm was designed to determine the role that visual-spatial (Cartesian) and motor (joint angles, activation patterns) coordinates play in the coding and learning of a complex movement sequence. Younger and older adults practiced a 16-element movement sequence with one limb on Day 1 and the contra-lateral limb on Day 2. Practice involved the same sequence with either the same visual-spatial or motor coordinates on the two days. Retention tests were conducted on Day 3. Results indicated that keeping the visual-spatial coordinates the same during acquisition resulted in superior retention only for younger adults. Results also indicated the overall slowing of sequential movement production for older adults which appears to result from these participants inability to impose a structure on the sequence. This provides strong evidence that the visual-spatial code plays a dominant role in complex movement sequences and this code is represented in an effector-independent manner for younger adults, but not for older adults.

Observation and physical practice: coding of simple motor sequences

An experiment was conducted to determine the coordinate system used in the development of movement codes during observation and utilized on later physical practice performance of a simple spatial-temporal movement sequence. The task was to reproduce a 1.3-s spatial-temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two transfer tests was used: a mirror transfer test where the same pattern of muscle activation and limb joint angles was required and a nonmirror transfer test where the visual-spatial pattern of the sequence was reinstated on the transfer test. The results indicated a strong advantage for participants in the physical practice condition when transferred to the mirror condition in which the motor coordinates (e.g., pattern of muscle activation and joint angles) were reinstated relative to transfer performance when the visual-spatial coordinates were reinstated (visual and spatial location of the target waveform). The observation group, however, demonstrated an advantage when the visual-spatial coordinates were reinstated. These results demonstrate that codes based in motor coordinates can be developed relatively quickly for simple rapid movement sequences when participants are provided physical practice, but observational practice limits the system to the development of codes based in visual-spatial coordinates. Performances of control participants, who were not permitted to practise or observe the task, were quite poor on all tests.

Role of action observation and action in sequence learning and coding

A complex sequence learning task was used to determine if the type of coding acquired through physical practice (PP), observation of the stimulus (Obs-S), or observation of stimulus and action (Obs-SA) differs between conditions and whether the type of observation influences subsequent learning of the task when physical practice was permitted. Participants in the Obs-S group were permitted to watch the sequentially illuminated stimuli on the screen. In the Obs-SA group participants could see both flexion-extension movements of the model's arm performing the sequence and the sequentially illuminated stimuli on the screen. Participants in the PP group actually performed the 16-element sequence with their dominant right arm. Delayed retention tests and two inter-manual transfer tests were completed following each of two acquisition sessions. First, the data indicated that learning the sequence structure, as revealed by response time per element, occurred similarly irrespective of the initial practice condition. Secondly, the movement sequence appeared to be coded in abstract visual-spatial coordinates resulting in effector-independent performance. Finally, observing the model's action and sequential stimuli allows participants to transfer the perceived aspects of the movement sequence into efficient coordination patterns when additional physical practice is permitted.

Inventory management

A critical aspect of blood transfusion is the timely provision of high quality blood products. This task remains a significant challenge for many blood services and blood systems reflecting the difficulty of balancing the recruitment of sufficient donors, the optimal utilization of the donor's gift, the increasing safety related restrictions on blood donation, a growing menu of specialized blood products and an ever-growing imperative to increase the efficiency of blood product provision from a cost perspective. As our industry now faces questions about our standard practices including whether or not the age of blood has a negative impact on recipients, it is timely to take a look at our collective inventory management practices. This International Forum represents an effort to get a snap shot of inventory management practices around the world, and to understand the range of different products provided for patients. In addition to sharing current inventory management practices, this Forum is intended to foster an exchange of ideas around where we see our field moving with respect to various issues including specialty products, new technologies, and reducing recipient risk from blood transfusion products.

[Herniation pits and their renaissance in association with femoroacetabular impingement]

Hernitation pits (HPs) of the femoral neck were first described in 1982. The purpose of this paper is to summarize the information concerning HPs published since then and to show their association with the diagnosis of femoroacetabular impingement (FAI) which has occurred within the last years. HPs are predominantly located at the anterior-superior femoral neck with a typical radiological appearance, which makes it possible to differentiate them from the numerous differential diagnoses mentioned. In the early publications HPs were described as a separate entity, while recent studies increasingly assign them to intra-osseous ganglia. In contrast to the early publications depicting HPs as an incidental finding, they are currently mainly mentioned in association with FAI and at the same time are partly considered to be a radiological indicator of FAI. In summary, HPs should always be recognized and documented because they may contribute to the diagnosis of FAI which is essential for preventing or delaying osteoarthritis of the hip joint in the early stage.

Pacing pattern and speed skating performance in competitive long-distance events

The present study was aimed to compare the pacing pattern adopted by women and men in races performed during a complete World Cup series. Elite skaters competed in long-distance races of different length (3,000, 5,000, and 10,000 m) and location (low/high altitude) where distribution of lap times were analyzed. Regardless of athletes' performance level, gender, or rinks' location, similar pacing patterns were observed in each event, which were characterized by an initial acceleration followed by a progressive delay in lap times-"positive pacing strategy". Differences in lap times were significant in each instance for women's 3,000 m (p < 0.001). For the 5,000 m races, laps 5-12 in women and laps 8-12 in men were slower compared with previous laps (p < 0.001, for both sexes). For men's 10,000 m, skaters performed only the first lap faster than the remaining laps (p < 0.001) with laps 2-7 not different from each other but faster than laps 19-24 (p < 0.05), which also did not differ from each other. Top-ranked compared with bottom-ranked skaters (p < 0.001) and male compared with female skaters (p < 0.001) were significantly faster at each lap, suggesting that technical or physiological or both aspects need to be developed in those. The significantly shorter lap times at high- compared with low-altitude races (p < 0.001) suggest that rinks' location appears to be important for performance outcome, at elite level.

Pacing and performance in competitive middle-distance speed skating

Data from speed skating during World Cup 1500-m middle-distance races were analyzed to (a) determine the time/velocity distribution during the race and (b) assess the impact of time spent in several race sectors on performance outcome. Absolute and relative sector times for the first 300 m (S1) and the following three 400-m laps (S2-S4) and their associations with total race time were analyzed for 53 female and 61 male skaters. Simple regression analyses revealed that both a short relative sector time later in the race (women in S3: p < .001; men in S3: p = .001) and a high relative sector time early in the race (women in S1: p < .001; men in S1: p = .08) were associated with a short total race time in the 1500-m middle-distance event. These findings suggest that for the best overall time it is important to be as fast as possible later in the race and not quite as fast during the first part of the race. Therefore, speed skating performance may be improved by maintaining a high velocity or by minimizing the decline from a high velocity during later race segments.

Intermanueller Transfer und Händigkeit

Zusammenfassung. In dem Experiment wurde der intermanuelle Transfer auf eine neue dynamische Anforderung und Händigkeit untersucht. Gegenstand ist das Lernen einer Bewegungssequenz. Die Aufgabe der Lerner bestand in dem Erwerb einer 16-Elementigen Bewegungssequenz. Nach einem anfänglichen Training einer Bewegungssequenz für Rechts- und Linkshänder in Abhängigkeit der Starthand (dominante, nicht-dominante Hand) wurden nach einem Intervall von 24 Stunden ein Behaltenstest und zwei Transfertests appliziert. In dem Behaltenstest musste die gelernte Sequenz mit der trainierten Hand ohne Zusatzlast (0 kg) reproduziert werden. In den beiden ausbalancierten Transfertests sollte sowohl mit der trainierten als auch mit der untrainierten kontralateralen Hand eine zusätzliche Masse von 1 kg bewegt werden. Die Ergebnisse zeigen, dass sowohl Rechts- als auch Linkshänder auf unterschiedliche dynamische Eigenschaften mit ihrer dominanten Hand transferieren können. Rechtshänder können sowohl mit der rechten als auch der linken Hand unabhängig von ihrer Starthand auf neue dynamische Anforderungen transferieren (Symmetrie). Eine Asymmetrie in dem Übertrag zeigt sich bei den Linkshändern, die unabhängig von ihrer trainierten Hand nicht auf ihre rechte Hand und auf eine veränderte dynamische Anforderung transferieren können.

Adenosine diphosphate-inducible platelet reactivity shows a pronounced age dependency in the initial phase of antiplatelet therapy with clopidogrel

BACKGROUND

Until recently, there were hardly any data on the antiplatelet effect of clopidogrel in advanced age. Like other metabolic processes, the conversion of clopidogrel to its active metabolite may be impaired in older patients, leading to high on-treatment residual ADP-inducible platelet reactivity.

OBJECTIVE

To investigate the age dependency of clopidogrel-mediated platelet inhibition.

PATIENTS AND METHODS

This was a prospective observational study. We determined adenosine 5'-diphosphate (ADP)-inducible platelet reactivity using light transmission aggregometry (LTA) and the VerifyNow P2Y12 assay in 191 patients on dual antiplatelet therapy after angioplasty and stenting for cardiovascular disease.

RESULTS

ADP-inducible platelet reactivity increased linearly with age after adjustment for cardiovascular risk factors, type of intervention, medication, C-reactive protein (CRP) and renal function [using LTA 0.36% of maximal aggregation per year, 95% CI 0.08-0.64%, P = 0.013; using the VerifyNow P2Y12 assay 3.2 P2Y12 reaction units (PRU) per year, 95% CI 1.98-4.41 PRU, P < 0.001]. ADP-inducible platelet reactivity was significantly higher in patients aged 75 years or older compared with younger patients (P = 0.003 for LTA and P < 0.001 for the VerifyNow P2Y12 assay). Further, high on-treatment residual ADP-inducible platelet reactivity was significantly more common among patients aged 75 years or older (P = 0.02 for LTA and P < 0.001 for the VerifyNow P2Y12 assay).

CONCLUSION

ADP-inducible platelet reactivity shows a pronounced age dependency in the initial phase of antiplatelet therapy with clopidogrel. The clinical implications of these findings need to be addressed in future trials.