Validation of a wearable system for 3D ambulatory L5/S1 moment assessment during manual lifting using instrumented shoes and an inertial sensor suit.

This study aimed to evaluate the accuracy of 3D L5/S1 moment estimates from an ambulatory measurement system consisting of a wearable inertial motion capture system (IMC) and instrumented force shoes (FSs), during manual lifting. Reference L5/S1 moments were calculated using an inverse dynamics bottom-up laboratory model (buLABmodel), based on data from a measurement system comprising optical motion capture (OMC) and force plates (FPs). System performance of (1) a bottom-up ambulatory model (buAMBmodel) using lower-body kinematic IMC and FS data, and (2) a top-down ambulatory model (tdAMBmodel) using upper-body kinematic IMC data and hand forces (HFs) were compared. HFs were estimated using full-body kinematic IMC data and FS forces. Eight males and eight females lifted a 10-kg box from different initial vertical/horizontal positions using either a free or an asymmetric lifting style. As a measure of system performance, root-mean-square (RMS) errors were calculated between the reference (buLABmodel) and ambulatory (tdAMBmodel &buAMBmodel) moments. The results showed two times smaller errors for the tdAMBmodel (averaged RMS errors < 20 Nm or 10% of peak extension moment) than for the buAMBmodel (average RMS errors < 40 Nm or 20% of peak extension moment). In conclusion, for ambulatory L5/S1 moment assessment with an IMC + FS system, using a top-down inverse dynamics approach with estimated hand forces is to be preferred over a bottom-up approach.

Correction to: Trunk, head and pelvis interactions in healthy children when performing seated daily arm tasks.

The authors inadvertently submitted a wrong figure part for publication. Figure 8b should be as follows.

Trunk, head and pelvis interactions in healthy children when performing seated daily arm tasks.

Development of trunk and head supportive devices for children with neuromuscular disorders requires detailed information about pelvis, trunk and head movement in interaction with upper extremity movement, as these are crucial for daily activities when seated in a wheelchair. Twenty-five healthy subjects (6-20 years old) were included to obtain insight in the physiological interactions between these segments and to assess maturation effects. Subjects performed a maximum range of trunk and head movement tasks and several daily tasks, including forward and lateral reaching. Movements of the arms, head, pelvis, and sub-sections of the trunk were recorded with an optical motion capture system. The range of motion of each segment was calculated. Contributions of individual trunk segments to the range of trunk motion varied with movement direction and therefore with the task performed. Movement of pelvis and all trunk segments in the sagittal plane increased significantly with reaching height, distance and object weight when reaching forward and lateral. Trunk movement in reaching decreased with age. Head movement was opposite to trunk movement in the sagittal (> 50% of the subjects) and transverse planes (> 75% of the subjects) and was variable in the frontal plane in most tasks. Both trunk and head movement onsets were earlier compared to arm movement onset. These results provide insight in the role of the upper body in arm tasks in young subjects and can be used for the design of trunk and head supportive devices for children with neuromuscular disorders.

Continuous ambulatory hand force monitoring during manual materials handling using instrumented force shoes and an inertial motion capture suit.

Hand forces (HFs) are commonly measured during biomechanical assessment of manual materials handling; however, it is often a challenge to directly measure HFs in field studies. Therefore, in a previous study we proposed a HF estimation method based on ground reaction forces (GRFs) and body segment accelerations and tested it with laboratory equipment: GFRs were measured with force plates (FPs) and segment accelerations were measured using optical motion capture (OMC). In the current study, we evaluated the HF estimation method based on an ambulatory measurement system, consisting of inertial motion capture (IMC) and instrumented force shoes (FSs). Sixteen participants lifted and carried a 10-kg crate from ground level while 3D full-body kinematics were measured using OMC and IMC, and 3D GRFs were measured using FPs and FSs. We estimated 3D hand force vectors based on: (1) FP+OMC, (2) FP+IMC and (3) FS+IMC. We calculated the root-mean-square differences (RMSDs) between the estimated HFs to reference HFs calculated based on crate kinematics and the GRFs of a FP that the crate was lifted from. Averaged over subjects and across 3D force directions, the HF RMSD ranged between 10-15N when using the laboratory equipment (FP + OMC), 11-18N when using the IMC instead of OMC data (FP+IMC), and 17-21N when using the FSs in combination with IMC (FS + IMC). This error is regarded acceptable for the assessment of spinal loading during manual lifting, as it would results in less than 5% error in peak moment estimates.

Is the Assessment of 5 Meters of Gait with a Single Body-Fixed-Sensor Enough to Recognize Idiopathic Parkinson's Disease-Associated Gait?

Quantitative assessment of gait in patients with Parkinson's disease (PD) is an important step in addressing motor symptoms and improving clinical management. Based on the assessment of only 5 meters of gait with a single body-fixed-sensor placed on the lower back, this study presents a method for the identification of step-by-step kinematic parameters in 14 healthy controls and in 28 patients at early-to-moderate stages of idiopathic PD. Differences between groups in step-by-step kinematic parameters were evaluated to understand gait impairments in the PD group. Moreover, a discriminant model between groups was built from a subset of significant and independent parameters and based on a 10-fold cross-validated model. The discriminant model correctly classified a total of 89.5% participants with four kinematic parameters. The sensitivity of the model was 95.8% and the specificity 78.6%. The results indicate that the proposed method permitted to reasonably recognize idiopathic PD-associated gait from 5-m walking assessments. This motivates further investigation on the clinical utility of short episodes of gait assessment with body-fixed-sensors.

Estimating 3D L5/S1 moments and ground reaction forces during trunk bending using a full-body ambulatory inertial motion capture system.

Inertial motion capture (IMC) systems have become increasingly popular for ambulatory movement analysis. However, few studies have attempted to use these measurement techniques to estimate kinetic variables, such as joint moments and ground reaction forces (GRFs). Therefore, we investigated the performance of a full-body ambulatory IMC system in estimating 3D L5/S1 moments and GRFs during symmetric, asymmetric and fast trunk bending, performed by nine male participants. Using an ambulatory IMC system (Xsens/MVN), L5/S1 moments were estimated based on the upper-body segment kinematics using a top-down inverse dynamics analysis, and GRFs were estimated based on full-body segment accelerations. As a reference, a laboratory measurement system was utilized: GRFs were measured with Kistler force plates (FPs), and L5/S1 moments were calculated using a bottom-up inverse dynamics model based on FP data and lower-body kinematics measured with an optical motion capture system (OMC). Correspondence between the OMC+FP and IMC systems was quantified by calculating root-mean-square errors (RMSerrors) of moment/force time series and the interclass correlation (ICC) of the absolute peak moments/forces. Averaged over subjects, L5/S1 moment RMSerrors remained below 10Nm (about 5% of the peak extension moment) and 3D GRF RMSerrors remained below 20N (about 2% of the peak vertical force). ICCs were high for the peak L5/S1 extension moment (0.971) and vertical GRF (0.998). Due to lower amplitudes, smaller ICCs were found for the peak asymmetric L5/S1 moments (0.690-0.781) and horizontal GRFs (0.559-0.948). In conclusion, close correspondence was found between the ambulatory IMC-based and laboratory-based estimates of back load.

The effects of guided discontinuation of antipsychotics on neurocognition in first onset psychosis.

OBJECTIVE: To assess the effects of second generation antipsychotics on neurocognitive function in patients with stable remission of first episode psychosis. METHODS: Fifty-three patients with first onset psychosis in the schizophrenia spectrum entered a randomised controlled trial of guided discontinuation (GD) versus maintenance treatment (MT) with second generation antipsychotics. A comprehensive neurocognitive test battery was administered at the time of remission and shortly after dose reduction or discontinuation (GD-group) or at the same time in the MT-group. RESULTS: With the exception of negative symptoms, PANSS scores decreased over time and neurocognition improved significantly on most tests in both groups. The GD-group, however, improved significantly more than the MT-group on three neurocognitive measures in the domain of speed of processing. CONCLUSION: These data suggest that, in first episode patients, dose reduction or discontinuation of second generation antipsychotics after stable remission is achieved, might improve neurocognitive function more than continuing second generation antipsychotics, suggesting a negative role for second generation antipsychotics, specifically in the domain of speed of processing.

[Typical and atypical antipsychotics: Is there a difference in their influence on neurocognition?]. / Typische en atypische antipsychotica bij patiënten met schizofrenie: is er verschil in invloed op neurocognitie?

BACKGROUND: Neurocognitive dysfunction is a core feature of schizophrenia and is related to the functional outcome of the illness. It has been suggested that the so-called atypical antipsychotics may have a more favourable influence on neurocognition than the older, typical antipsychotics and thus also on the functional outcome. AIM: To review the recent scientific literature concerning the effects of antipsychotics on neurocognition. METHOD: The literature was reviewed systematically via the most important databases. RESULTS: Meta-analyses suggest that atypical antipsychotics have moderate, positive effects on neurocognition and in that respect are more beneficial than typical antipsychotics. Recent studies, however, challenge this finding. CONCLUSION: The reported positive, cognitive effects of atypical antipsychotics are slight, particularly compared to the severity of neurocognitive dysfunction found in schizophrenia. In clinical practice there seem to be no convincing reason for attaching much weight to any differential effects that typical or atypical antipsychotics may have on neurocognition.

[Routine Outcome Monitoring for patients with severe mental illness: a consensus document]. / Routine outcome monitoring voor patiënten met ernstige psychiatrische aandoeningen; een consensusdocument.

BACKGROUND: Routine outcome monitoring (ROM) means the assessment of the patient's condition on a routine basis using instruments. So far there is no consensus about which instruments should be used for ROM with severely mentally ill patients (ROM-SMI). AIM: To reach a consensus about instruments for ROM-SMI in the Netherlands and Belgium and to create possibilities for comparison of ROM data. METHOD: This article discusses the consensus document of the National Remission Working Group for ROM in patients with smi and covers the following topics: reasons for ROM-SMI, domains for ROM-SMI and appropriate instruments, logistics and analyses of the data. RESULTS: Patients with SMI have problems in several domains. These can be assessed by collecting information about psychiatric symptoms, addiction, somatic problems, general functioning, needs, quality of life and care satisfaction. Potential instruments for ROM-SMI are short, valid, reliable and assess several domains, taking the patient's perspective into account, and have been used in national and international research. The working group advises institutions to choose from a limited set of instruments. After the scores have been aggregated and standardised, comparisons can be drawn. ROM-SMI data can be interpreted more meaningfully, if outcome data are supplemented with data regarding patient characteristics and the treatment interventions already applied. CONCLUSION: It should be possible to reach a consensus about instruments for ROM-SMI and the way in which they should be used. The use of identical instruments will lead to improvements in mental health care and create possibilities for comparison (benchmarking) and research.

Working height, block mass and one- vs. two-handed block handling: the contribution to low back and shoulder loading during masonry work.

The goal of this study was to compare the effects of the task variables block mass, working height and one- vs. two-handed block handling on low back and shoulder loading during masonry work. In a mock-up of a masonry work site, nine masonry workers performed one- and two-handed block-lifting and block-placing tasks at varying heights (ranging from floor to shoulder level) with blocks of varying mass (ranging from 6 to 16 kg). Kinematics and ground reaction forces were measured and used in a 3-D linked segment model to calculate low back and shoulder loading. Increasing lifting height appeared to be the most effective way to reduce low back loading. However, working at shoulder level resulted in relatively high shoulder loading. Therefore, it was recommended to organise masonry work in such a way that blocks are handled with the hands at about iliac crest height as much as possible.

Effect of block weight on work demands and physical workload during masonry work.

The effect of block weight on work demands and physical workload was determined for masons who laid sandstone building blocks over the course of a full work day. Three groups of five sandstone block masons participated. Each group worked with a different block weight: 11 kg, 14 kg or 16 kg. Productivity and durations of tasks and activities were assessed through real time observations at the work site. Energetic workload was also assessed through monitoring the heart rate and oxygen consumption at the work site. Spinal load of the low back was estimated by calculating the cumulated elastic energy stored in the lumbar spine using durations of activities and previous data on corresponding compression forces. Block weight had no effect on productivity, duration or frequency of tasks and activities, energetic workload or cumulative spinal load. Working with any of the block weights exceeded exposure guidelines for work demands and physical workload. This implies that, regardless of block weight in the range of 11 to 16 kg, mechanical lifting equipment or devices to adjust work height should be implemented to substantially lower the risk of low back injuries.

The effects of ergonomic interventions on low back moments are attenuated by changes in lifting behaviour.

This study investigated the effects of ergonomic interventions involving a reduction of the mass (from 16 to 11 and 6 kg) and an increase in the initial lifting height (from pallet height to 90 cm above the ground) of building blocks in a mock-up of an industrial depalletizing task, investigating lifting behaviour as well as low back moments (calculated using a 3-D linked segment model). Nine experienced construction workers participated in the experiment, in which they removed building blocks from a pallet in the way they normally did during their work. Most of the changes in lifting behaviour that were found would attenuate the effect of the investigated interventions on low back moments. When block mass was reduced from 16 to 6 kg, subjects chose to lift the building block from a 10 (SD 10) cm greater distance from the front edge of the pallet and with a 100 (SD 66) degrees/s(2) higher trunk angular acceleration. When initial lifting height was increased, subjects chose to shift the building blocks less before actually lifting them, resulting in a 10.7 (SD 10) cm increase in horizontal distance of the building blocks relative to the body at the instant of peak net total moment. Despite these changes in lifting behaviour, the investigated ergonomic interventions still reduced the net total low back moment (by 4.9 (SD 2.0) Nm/kg when block mass was reduced and 53.6 (SD 41.0) Nm when initial lifting height was increased).

Redox-mediated decolorization of synthetic dyes by fungal laccases.

Laccases from the lignin-degrading basidiomycetes Trametes versicolor, Polyporus pinisitus and the ascomycete Myceliophthora thermophila were found to decolorize synthetic dyes to different extents. Differences were attributed to the specific catalytic properties of the individual enzymes and to the structure of the dyes. Due to their higher oxidative capacities, the laccases from the two basidiomycetes decolorized dyes more efficiently than that of the ascomycete. The azo dye Direct Red 28, the indigoid Acid Blue 74 and anthraquinonic dyes were directly enzymatically decolorized within 16 h. The addition of 2 mM of the redox-mediator 1-hydroxybenzotriazole further improved and facilitated the decolorization of all nine dyes investigated. Laccases decolorized dyes both individually and in complex mixtures in the presence of bentonite or immobilized in alginate beads. Our data suggest that laccase/mediator systems are effective biocatalysts for the treatment of effluents from textile, dye or printing industries.

The complexity of external acoustic detection of defects in Björk-Shiley convexoconcave heart valves.

Fractures in Björk-Shiley convexoconcave (BScc) heart valves have raised questions about the feasibility of early diagnosis of technical defects by means of acoustic assessment. Three laboratory tests were conducted. To establish acoustic fingerprints, 66 valves with a defect, such as single-leg fracture (SLF) or single-leg separation (SLS), or without a defect were connected with a contact sensor and excited by dropping a small metal ball onto the outlet strut. In the second test, we simulated the valve sound propagation within the thorax. In the third test, intact, SLF, and SLS valves were placed in a mock heart immersed in a large water tank. We observed a resonance frequency corresponding with valve size and presence of defects. The second test showed that both the chest wall and the lungs created numerous reflections. This led to a substantial overlap of the original pulse frequencies and the frequencies measured. The third test confirmed that submersion of the chest in water can significantly reduce chest wall reflections. Reliable noninvasive assessment of BScc valve clicks for the presence of defects of the outlet strut is hampered by complex sound propagation within the thorax and variability of valve excitation. Acoustic fingerprints to diagnose mechanical defects should be integrated in valve design.

Action potential and contractility changes in [Na(+)](i) overloaded cardiac myocytes: a simulation study.

Sodium overload of cardiac cells can accompany various pathologies and induce fatal cardiac arrhythmias. We investigate effects of elevated intracellular sodium on the cardiac action potential (AP) and on intracellular calcium using the Luo-Rudy model of a mammalian ventricular myocyte. The results are: 1) During rapid pacing, AP duration (APD) shortens in two phases, a rapid phase without Na(+) accumulation and a slower phase that depends on [Na(+)](i). 2) The rapid APD shortening is due to incomplete deactivation (accumulation) of I(Ks). 3) The slow phase is due to increased repolarizing currents I(NaK) and reverse-mode I(NaCa), secondary to elevated [Na(+)](i). 4) Na(+)-overload slows the rate of AP depolarization, allowing time for greater I(Ca(L)) activation; it also enhances reverse-mode I(NaCa). The resulting increased Ca(2+) influx triggers a greater [Ca(2+)](i) transient. 5) Reverse-mode I(NaCa) alone can trigger Ca(2+) release in a voltage and [Na(+)](i)-dependent manner. 6) During I(NaK) block, Na(+) and Ca(2+) accumulate and APD shortens due to enhanced reverse-mode I(NaCa); contribution of I(K(Na)) to APD shortening is negligible. By slowing AP depolarization (hence velocity) and shortening APD, Na(+)-overload acts to enhance inducibility of reentrant arrhythmias. Shortened APD with elevated [Ca(2+)](i) (secondary to Na(+)-overload) also predisposes the myocardium to arrhythmogenic delayed afterdepolarizations.

Incidental detection of acute myocardial infarction during routine performance of three-dimensional dynamic MR angiographic study with dynamic injection of gadolinium.

We report on the MR appearance of acute myocardial infarction in a 61-year-old man with Ehlers-Danlos syndrome using motion-independent, T2-weighted echo train spin echo and immediate post-gadolinium three-dimensional gradient echo imaging performed as an MRI angiographic study of the aortic arch. The region of acute infarction was of high signal intensity on the T2-weighted images and demonstrated greatly diminished enhancement on the immediate post-gadolinium three-dimensional gradient echo images. MRI findings showed good correlation with autopsy specimens obtained within 24 hours of the MRI study.

Rapid identification of bacterially contaminated platelets using reagent strips: glucose and pH analysis as markers of bacterial metabolism.

BACKGROUND: One in every 1000 units of platelets is bacterially contaminated, which puts patients at risk for transfusion-associated sepsis and death. However, there is currently no screening test in place to detect contaminated units. The use of commercially available multiple-reagent urine dipsticks for this purpose was evaluated. STUDY DESIGN AND METHODS: Platelet concentrates were inoculated with either sterile saline or suspensions of Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Klebsiella pneumoniae, or Serratia marcescens to a final concentration of 50 colony-forming units (CFU) per mL. The platelets were analyzed daily by the use of multiple-reagent strips, quantitative culture, and glucometry. RESULTS: B cereus grew rapidly, reaching 10(7) CFU per mL 1 day after inoculation, while S. epidermidis grew slowly, achieving similar concentration 4 to 6 days after inoculation. Two of 10 dipstick reagents, glucose and pH, proved useful in detecting bacteria. Both were lower in bacterially contaminated units than in controls. Glucose data obtained from automated analyzers validated the dipstick data. All organisms were detected at concentrations > or = 10(7) CFU per mL, and S. aureus and K. pneumoniae were detected in the range of 10(3) to 10(5) CFU per mL. CONCLUSION: The multiple-reagent test used had a sensitivity and specificity of 95 percent (> or = 10(7) CFU/mL) and 98 to 100 percent, respectively. These data indicate that urine dipsticks can be used to rapidly and inexpensively detect bacterial contamination in platelet concentrates, which potentially will reduce morbidity and mortality at minimal cost.

[Diagnosis of performance anxiety in educational spelling tests: new results of the psychometric properties and validity of a relevant brief scale]. / Die Diagnose von Leistungsangst vor schulischen Rechtschreibsituationen: Neue Ergebnisse zu den psychometrischen Eigenschaften und zur Validität einer entsprechenden Kurzskala.

In the present study the psychometric properties and the criterion-related validity of a short scale for measuring students' spelling-specific test anxiety were analyzed. This scale consists of 13 self-rating items which reflect students' worry and emotionality reactions in face of spelling requirements at school. Along with some concurrent criterion variables (such as general self-esteem, academic and spelling-related self-concept, and spelling-related attributions, spelling and mathematics achievement, regressive classroom behavior), data were gathered at the beginning (N = 274) and, nearly 11 months later, at the end (N = 257) of the school year. At both measurement times, principal component analyses correspondingly revealed one common test anxiety factor and led to an overall scale format. This final scale solutions appeared to be sufficiently reliable and stable. Furthermore, their relationships to the various criterion variables largely turned out as theoretically expected. Especially, the spelling-specific test anxiety scores could be best predicted by spelling-specific self-concept and by spelling achievement, respectively. Thus, the findings of the present study could replicate the results of a previous pilot study and provided further support for the construct validity of interpretations based upon the spelling-specific test anxiety scale.

Association of pancreatic adenocarcinoma, mild lung disease, and delta F508 mutation in a cystic fibrosis patient.

A case of adenocarcinoma of the pancreas and mild lung disease in a 39-year-old man homozygous for the delta F508 cystic fibrosis mutation is presented. Cystic fibrosis is the most common lethal genetic disease in Caucasians, and is most commonly associated with severe obstructive lung disease. To our knowledge, this is only the fifth case of adenocarcinoma of the pancreas in a CF patient to be reported and the first case for which molecular data are available. The rare incidence of this type of malignancy in the general population suggests a possible association of CF with this malignant disease.

[Regional differences in frequency-corrected QT duration in multi-electrode ECG in ventricular extrasystole]. / Regionale Differenzen der frequenzkorrigierten QT-Dauer im Multi-Elektroden-EKG bei ventrikulärer Extrasystolie.

Issuing from the pathophysiological significance of a prolongation of the QT-time for the diagnostics and therapy of ventricular arrhythmias examinations on 15 patients with ventricular extrasystoles by means of multi-electrode-ECG are demonstrated in comparison to 10 test persons with healthy heart. 2 regions on the thoracic surface with significant prolongation of the QT-time in the group of patients are described: Regio hypochondriaca parasternally left and left posterior axillary line at the level of the 7th and 8th thoracic vertebral body.