Personality in speed skaters with skater's cramp: A preliminary cross-sectional study.

OBJECTIVE: Skater's cramp is a debilitating disorder in expert speedskaters and recent evidence from muscle and movement studies nominate it is a task-specific dystonia (TSD). Building on these studies we investigated clinical features and personality in skater's cramp, hypothesizing that similar to other TSDs, trait emotionality would be higher in affected skaters. METHODS: In a cross-sectional study we employed the HEXACO inventory to examine the personality of a cohort of skaters with skater's cramp (n = 26) compared to age, sex, and experience-matched controls (n = 28). Affected skaters were selected based on relevant clinical features important to the diagnosis of TSD. RESULTS: Sentimentality (a sub-factor of emotionality) was higher in affected skaters, but only in the male population. Extraversion was lower in skaters with skater's cramp. Clinical findings resembled other forms of TSD. DISCUSSION: Higher sentimentality is in line with previous studies in TSD. Lower Extraversion in affected skaters was an unexpected finding that may be a new feature of skater's cramp and TSD. Due to our small sample size and cross-sectional design, these findings are preliminary, but offer tentative evidence of personality differences in skater's cramp in line with TSD.

Inter-muscular coherence in speed skaters with skater's cramp.

INTRODUCTION: Skater's cramp is a career-ending movement disorder in expert speed skaters noted to be a likely task-specific dystonia. In other movement disorders, including task-specific dystonia, studies have found evidence of central dysregulation expressed as higher inter-muscular coherence. We looked at whether inter-muscular coherence was higher in affected skaters as a possible indicator that it is centrally driven, and by extension further evidence it is a task-specific dystonia. METHODS: In 14 affected and 14 control skaters we calculated inter-muscular coherence in the theta-band in a stationary task where tonic muscle activation was measured at 10%, 20% and 50% of maximum voluntary contraction. Additionally, we calculated wavelet coherence while skating at key moments in the stroke cycle. RESULTS: Coherence did not differ in the stationary activation task. While skating, coherence was higher in the impacted leg of affected skaters compared to their non-impacted leg, p = .05, η2 = 0.031, and amplitude of electromyography correlated with coherence in the impacted leg, p = .009, R2adjusted = 0.41. A sub-group of severely affected skaters (n = 6) had higher coherence in the impacted leg compared to the left and right leg of controls, p = .02, Cohen's d = 1.59 and p = .01, Cohen's d = 1.63 respectively. Results were less clear across the entire affected cohort probably due to a diverse case-mix. CONCLUSION: Our results of higher coherence in certain severe cases of skater's cramp is preliminary evidence of a central dysregulation, making the likelihood it is a task-specific dystonia higher.

Foot placement variables of pedestrians in community setting during curve walking.

BACKGROUND: There is no precise description of changes of gait during curve walking. Research in curve walking is exclusively performed in clinical settings. RESEARCH QUESTION: Is there a difference in foot placement variables between the inner- and the outer leg during curve walking in a natural environment? And are these differences correlated with time or the curvature of the path? METHOD: During this observational study, camera footage was shot on a crossing where pedestrians were not aware of being filmed. Participants (n = 21, male, 18-40 yrs) were selected from this video footage. Using the software package "Movieprocessing", the kinematic variables (time, curvature, stride length, step length, step width and relative foot angle (RFA)) were extracted from the collected data. A MANOVA and Pearson correlation test were performed to explore the data. RESULTS: MANOVA showed no significant differences in stride length and step length between inner- and outer leg. In contrast, a significant difference between the inner (M = 0.06, SD = 0.05) and outer leg (M = 0.10, SD = 0.06, F(20,256) = 3.577, p < .001) for the step width, and the inner (M = 11.72, SD = 7.99) and outer leg (M = 11.30, SD = 8.07, F(20,256) = 4.542, p < .001) for RFA was found. Pearson correlation was significant for curvature and step width for both legs pooled (r = .28, p < .01) and the outer leg (r = .64, p < .01), as well for time and RFA in the inner (r= -.25, p < .01) and outer leg (r = .213, p < .01). SIGNIFICANCE: This research funds further research in curve walking in natural conditions, since curve walking is found to be performed non-symmetrically and not determined by geometrics but by choice. Foot placement variables change gradually and differently for both legs during walking a curve.

Passive anterior tibia translation in anterior cruciate ligament-injured, anterior cruciate ligament-reconstructed and healthy knees: a systematic review.

Anterior tibia translation (ATT) is mainly prevented by the anterior cruciate ligament. Passive ATT tests are commonly used to diagnose an anterior cruciate ligament (ACL) injury, to select patients for an ACL reconstruction (ACLR), and as an outcome measure after an ACLR. The aim of this review was to present an overview of possible factors determining ATT. A second purpose was to give a summary of the ATT measured in the literature in healthy, ACL-injured and ACLR knees and a comparison between those groups. A literature search was conducted with PubMed. Inclusion criteria were full-text primary studies published in English between January 2006 and October 2016. Studies included reported ATT in explicit data in healthy as well as ACL-injured or ACLR knees or in ACL-injured as well as ACLR knees. Sixty-one articles met inclusion criteria. Two articles measured the ATT in healthy as well as ACL-injured knees, 51 in ACL-injured as well as in ACLR knees, three in ACLR as well as in healthy knees and three in healthy, ACL-injured and ACLR knees. A difference in ATT is found between healthy, contralateral, ACLR and ACL-injured knees and between chronic and acute ACL injury. Graft choices and intra-articular injuries are factors which could affect the ATT. The mean ATT was lowest to highest in ACLR knees using a bone-patella tendon-bone autograft, ACLR knees using a hamstring autograft, contralateral healthy knees, healthy knees, ACLR knees with an allograft and ACL-injured knees. Factors which could affect the ATT are graft choice, ACL injury or reconstruction, intra-articular injuries and whether an ACL injury is chronic or acute. Comparison of ATT between studies should be taken with caution as a high number of different measurement methods are used. To be able to compare studies, more consistency in measuring devices used should be introduced to measuring ATT. The clinical relevance is that an autograft ACLR might give better results than an allograft ACLR as knee laxity is greater when using an allograft tendon. LEVEL OF EVIDENCE: III.

Effects of high heeled shoes on gait. A review.

BACKGROUND: Walking in high heels (HH) may alter gait in various ways, which may be of importance to designers and physicians. RESEARCH QUESTION: How does walking in high heels alter gait and how can this be explained from a biomechanical and control point of view. METHODS: Relevant literature has been collected in which high heeled walking was studied, after which the results were bundled and interpreted in a framework of biomechanics and control. RESULTS: Major changes were found in the rollover function of the feet, the ankle and knee joints and the lower back, while step length and balance were compromised. An increase in heel height forces the foot in an increased plantar flexion, which in its turn increases knee flexion and lordosis of the lower back. All changes can be related with each other in a plausible pattern of movement and control.

Boron difluorides with formazanate ligands: redox-switchable fluorescent dyes with large stokes shifts.

The synthesis of a series of (formazanate)boron difluorides and their 1-electron reduction products is described. The neutral compounds are fluorescent with large Stokes shifts. DFT calculations suggest that a large structural reorganization accompanies photoexictation and accounts for the large Stokes shift. Reduction of the neutral boron difluorides occurs at the ligand and generates the corresponding radical anions. These complexes are non-fluorescent, allowing switching of the emission by changing the ligand oxidation state.

Folic acid supplementation influences the distribution of neural tube defect subtypes: A registry-based study.

Periconceptional folic acid (FA) reduces neural tube defect (NTD) risk, but seems to have a varying effect per NTD subtype. We aimed to study the effect of FA supplementation on NTD subtype distribution using data from EUROCAT Northern Netherlands. We included all birth types with non-syndromal NTDs born in 1997-2012. By Fisher's exact test we analyzed possible differences in NTD subtype distribution between a correct FA supplementation group and incorrect FA supplementation group. We found proportionally fewer cervical/thoracic spina bifida cases and more lumbar/sacral spina bifida cases in the correct FA supplementation group, irrespective of the presence of the main NTD risk factors. The effect on NTD subtype distribution was only seen when FA supplementation was started before conception. We conclude that FA not only prevents the occurrence of a significant proportion of NTDs, but might also decrease the severity of NTDs, as long as supplementation is started before conception.

A systematic review of instruments for assessment of capacity in activities of daily living in children with developmental co-ordination disorder.

Children with developmental co-ordination disorder (DCD) face evident motor difficulties in activities of daily living (ADL). Assessment of their capacity in ADL is essential for diagnosis and intervention, in order to limit the daily consequences of the disorder. The aim of this study is to systematically review potential instruments for standardized and objective assessment of children's capacity in ADL, suited for children with DCD. As a first step, databases of MEDLINE, EMBASE, CINAHL and PsycINFO were searched to identify studies that described instruments with potential for assessment of capacity in ADL. Second, instruments were included for review when two independent reviewers agreed that the instruments (1) are standardized and objective; (2) assess at activity level and comprise items that reflect ADL; and (3) are applicable to school-aged children that can move independently. Out of 1507 publications, 66 publications were selected, describing 39 instruments. Seven of these instruments were found to fulfil the criteria and were included for review: the Bruininks-Oseretsky Test of Motor Performance-2 (BOT2); the Do-Eat (Do-Eat); the Movement Assessment Battery for Children-2 (MABC2); the school-Assessment of Motor and Process Skills (schoolAMPS); the Tuffts Assessment of Motor Performance (TAMP); the Test of Gross Motor Development (TGMD); and the Functional Independence Measure for Children (WeeFIM). As a third step, for the included instruments, suitability for children with DCD was discussed based on the ADL comprised, ecological validity and other psychometric properties. We concluded that current instruments do not provide comprehensive and ecologically valid assessment of capacity in ADL as required for children with DCD.

Application unit for the administration of contrast gases for pulmonary magnetic resonance imaging: optimization of ventilation distribution for (3) He-MRI.

PURPOSE: MRI of lung airspaces using gases with MR-active nuclei ((3) He, (129) Xe, and (19) F) is an important area of research in pulmonary imaging. The volume-controlled administration of gas mixtures is important for obtaining quantitative information from MR images. State-of-the-art gas administration using plastic bags (PBs) does not allow for a precise determination of both the volume and timing of a (3) He bolus. METHODS: A novel application unit (AU) was built according to the requirements of the German medical devices law. Integrated spirometers enable the monitoring of the inhaled gas flow. The device is particularly suited for hyperpolarized (HP) gases (e.g., storage and administration with minimal HP losses). The setup was tested in a clinical trial (n = 10 healthy volunteers) according to the German medicinal products law using static and dynamic ventilation HP-(3) He MRI. RESULTS: The required specifications for the AU were successfully realized. Compared to PB-administration, better reproducibility of gas intrapulmonary distribution was observed when using the AU for both static and dynamic ventilation imaging. CONCLUSION: The new AU meets the special requirements for HP gases, which are storage and administration with minimal losses. Our data suggest that gas AU-administration is superior to manual modes for determining the key parameters of dynamic ventilation measurements.

Altered head orientation patterns in children with idiopathic scoliosis in conditions with sensory conflict.

PURPOSE: Idiopathic scoliosis (IS) is the most common spinal deformity in adolescents. Defective postural equilibrium may be a contributing factor. The information of the three sensory systems combined enables the formation of a central representation of head position and body posture. Comparison of head angles of girls with and without scoliosis may result in a difference in head orientation. METHODS: 25 girls with IS and 16 girls without scoliosis (NS) between the age of 10-16 years stand in a special constructed box on a roll-tilting platform (tilt -14° to +14°). RESULTS: NS and IS subjects behave quite similarly if there is no sensory conflict, but if there is conflict, the differences between the two groups are greater, especially within the 13- to 14-year-old category. CONCLUSIONS: The differences between groups for different age categories suggest that the process of development of sensory integration for estimation of verticality appears to be different for girls with scoliosis.

Effect of fatigue on landing performance assessed with the landing error scoring system (less) in patients after ACL reconstruction. A pilot study.

BACKGROUND: Fatigue has been shown to affect performance of hop tests in patients after anterior cruciate ligament reconstruction (ACLR) compared to uninjured controls (CTRL). This may render the hop test less sensitive in detecting landing errors. The primary purpose of this study was to investigate the effect of lower extremity fatigue on landing performance assessed with the Landing Error Scoring System (LESS) in patients after ACLR compared to a CTRL group. It is plausible that fatigue would have an effect on confidence and risk appraisal in the ACLR group. The secondary purpose was to determine the relationship between psychological responses and LESS scores after fatigue. METHODS: Twelve patients following ACLR (6 males, 6 females) who were tested at 10 ± 2.4 months after surgery participated in the current study and were compared to 10 subjects in the control group (5 males, 5 females). Subjects performed a jump-landing task and the landing was assessed using the Landing Error Scoring System (LESS) both before and after fatigue. Digital video camcorders recorded frontal and sagittal plane views of the subject performing the task. The LESS was scored using video replay. Psychological responses in the ACLR group were assessed with the ACL-RSI questionnaire. RESULTS: Patients after ACLR had a median LESS of 6.5 which reflects a poor result (LESS >6) in the pre-fatigue condition compared to controls who had a LESS of 2.5 which is considered excellent (≤4). In the post-fatigue condition, median LESS in patients after ACLR increased to 7.0 whereas in the control group the LESS increased to 6.0 both of which reflect a poor result. The median increase in LESS was larger in the control (2.0) group compared to patients after ACLR (1.0) but the difference was not significant (p=0.165). CONCLUSIONS: Patients after ACLR have higher LESS scores at baseline compared to a control group. Fatigue resulted in an increase in scores on the LESS in both groups. LEVEL OF EVIDENCE: 3b.

Synthesis and ligand-based reduction chemistry of boron difluoride complexes with redox-active formazanate ligands.

Mono(formazanate) boron difluoride complexes (LBF2), which show remarkably facile and reversible ligand-based redox-chemistry, were synthesized by transmetallation of bis(formazanate) zinc complexes with boron trifluoride. The one-electron reduction product [LBF2](-)[Cp2Co](+) and a key intermediate for the transmetallation reaction, the six-coordinate zinc complex (L(BF3))2Zn were isolated and fully characterized.

Return of normal gait as an outcome measurement in acl reconstructed patients. A systematic review.

BACKGROUND: Current clinical outcome measurements may overestimate the long term success of anterior cruciate ligament reconstruction (ACLR). There is a need to understand biomechanics of the knee joint during daily activities. This systematic review provides a comprehensive overview of the literature related to gait in patients following ACLR. The purpose of this systematic review was to investigate the available literature and provide a comprehensive overview of kinematic and kinetic variables that present during gait in patients after ACLR. METHODS: A literature search was performed in AMED, CINAHL, EMBASE, Medline and Scopus between January 2000 and October 2012. Inclusion criteria included articles written in English, German or Dutch, and those reporting on gait analysis in patients after ACLR. Kinematic and/or kinetic data of the uninjured and ACLR knee and healthy controls (CTRL) were outcome measurements of interest. Each study's methodological quality was assessed using the Critical Appraisal Skills Programme critical appraisal tool. RESULTS: Twenty two studies fulfilled the inclusion criteria. A total of 479 patients with a mean age of 27.3 were examined. Time between the injury and surgery and ranged from 3 weeks to 5.7 years. Gait analysis was done at a mean of 29.3 months after surgery. Gait was found to be altered in the sagittal, frontal and transverse planes after ACLR and may take months or years to normalize, if normalization occurs at all. CONCLUSION: Patients after ACLR have altered gait patterns that can persist for up to five years after surgery. It is imperative that rehabilitation techniques are examined in order to minimize changes in knee biomechanics during gait, as they have the potential to impact on the development of osteoarthritis. LEVEL OF EVIDENCE: 3a.

Recycling of 3He from lung magnetic resonance imaging.

We have developed the means to recycle (3) He exhaled by patients after imaging the lungs using magnetic resonance of hyperpolarized (3) He. The exhaled gas is collected in a helium leak proof bag and further compressed into a steel bottle. The collected gas contains about 1-2% of (3) He, depending on the amount administered and the number of breaths collected to wash out the (3) He gas from the lungs. (3) He is separated from the exhaled air using zeolite molecular sieve adsorbent at 77 K followed by a cold head at 8 K. Residual gaseous impurities are finally absorbed by a commercial nonevaporative getter. The recycled (3) He gas features high purity, which is required for repolarization by metastability exchange optical pumping. At present, we achieve a collection efficiency of 80-84% for exhaled gas from healthy volunteers and cryogenic separation efficiency of 95%.

Feasibility of photoelectron sources with sharp lines of stable energy between 20 and 80 keV.

Photo-absorption of γ-rays in thin Al, Co, Ti, and Mo convertors was examined with the aim to produce quasi monoenergetic photoelectrons having an energy spread of 0.5-4.7eV about mean kinetic energies at discrete values between 18632 and 80321eV. The photoelectron rates were estimated for commercial photon sources of (241)Am, (119m)Sn, (125m)Te and (109)Cd with activities of 0.55-3.7GBq. Photoelectrons ejected by (241)Am γ- and X-rays from Co convertors were measured with two different electron spectrometers and obtained energy spectra were compared with Monte Carlo predictions.

Recurrent and founder mutations in the Netherlands: mutation p.K217del in troponin T2, causing dilated cardiomyopathy.

Background. About 30% of dilated cardiomyopathy (DCM) cases are familial. Mutations are mostly found in the genes encoding lamin A/C, beta-myosin heavy chain and the sarcomeric protein cardiac troponin-T (TNNT2). Mutations in TNNT2 are reported in approximately 3% of DCM patients. The overall phenotype caused by TNNT2 mutations is thought to be a fully penetrant, severe disease. This also seems to be true for a recurrent deletion in the TNNT2 gene; p.K217del (also known as p.K210del). Methods. We compared the phenotype of all Dutch patients identified as carrying the TNNT2 p.K217del mutation with those described in the literature. All index patients underwent cardiological evaluation. Family screening was done in all described families. Results. Six DCM patients carrying the TNNT2 p.K217del mutation were identified from four Dutch families. Mean age of disease manifestation was 33 years. Heart transplantation was required in three of them at ages 12, 18 and 19 years. These outcomes are comparable with those described in the literature. Conclusion. Carriers of the TNNT2 p.K217del mutation in our Dutch families, as well as in families described in the literature before, generally show a severe, early-onset form of DCM. (Neth Heart J 2010;18:478-85.).

Magnetized boxes for housing polarized spins in homogeneous fields.

We present novel types of permanently magnetized as well as current powered boxes built from soft-ferromagnetic materials. They provide shielded magnetic fields which are homogeneous within a large fraction of the enclosed volume, thus minimizing size, weight, and costs. For the permanently magnetized solutions, homogenization is achieved either by an optimized distribution of the permanent field sources or by jacketing the field with a soft-ferromagnetic cylindrical shell which is magnetized in parallel to the enclosed field. The latter principle may be applied up to fields of about 0.1T. With fields of about 1mT, such boxes are being used for shipping spin-polarized (3)He worldwide for MRI purposes. For current powered boxes, we present concepts and realizations of uniaxial and tri-axial shielded magnetic fields which are homogeneous on the level of 10(-4) within the entire shielded volume. This is achieved by inserting tightly fitting solenoids into a box from soft-magnetic material. The flexible tri-axial solution suits in particular laboratory applications, e.g. for establishing a spin quantization axis.

Abnormal landing strategies after ACL reconstruction.

The objective was to analyze muscle activity and movement patterns during landing of a single leg hop for distance after anterior cruciate ligament (ACL) reconstruction. Nine (six males, three females) ACL-reconstructed patients 6 months after surgery and 11 (eight males, three females) healthy control subjects performed the hop task. Electromyographic signals from lower limb muscles were analyzed to determine onset time before landing. Biomechanical data were collected using an Optotrak Motion Analysis System and force plate. Matlab was used to calculate kinetics and joint kinematics. Side-to-side differences in ACL-reconstructed patients and healthy subjects as well as differences between the patients and control group were analyzed. In ACL-reconstructed limbs, significantly earlier onset times were found for all muscles, except vastus medialis, compared with the uninvolved side. The involved limbs had significantly reduced knee flexion during the take-off and increased plantarflexion at initial contact. The knee extension moment was significantly lower in the involved limb. In the control group, significantly earlier onset times were found for the semitendinosus, vastus lateralis and medial gastrocnemius of the non-dominant side compared with the dominant side. Muscle onset times are earlier and movement patterns are altered in the involved limb 6 months after ACL reconstruction.

Uphill and downhill walking in unilateral lower limb amputees.

OBJECTIVE: To study adjustment strategies in unilateral amputees in uphill and downhill walking. DESIGN: Observational cohort study. SUBJECTS: Seven transfemoral, 12 transtibial unilateral amputees and 10 able-bodied subjects. METHODS: In a motion analysis laboratory the subjects walked over a level surface and an uphill and downhill slope. Gait velocity and lower limb joint angles were measured. RESULTS: In uphill walking hip and knee flexion at initial contact and hip flexion in swing were increased in the prosthetic limb of transtibial amputees. In downhill walking transtibial amputees showed more knee flexion on the prosthetic side in late stance and swing. Transfemoral amputees were not able to increase prosthetic knee flexion in uphill and downhill walking. An important adjustment strategy in both amputee groups was a smaller hip extension in late stance in uphill and downhill walking, probably related with a shorter step length. In addition, amputees increased knee flexion in early stance in the non-affected limb in uphill walking to compensate for the shorter prosthetic limb length. In downhill walking fewer adjustments were necessary, since the shorter prosthetic limb already resulted in lowering of the body. CONCLUSION: Uphill and downhill walking can be trained in rehabilitation, which may improve safety and confidence of amputees. Prosthetic design should focus on better control of prosthetic knee flexion abilities without reducing stability.