Complex relationships among personality traits, job characteristics, and work behaviors

The aim of the study was to investigate the additive, mediating, and moderating effects of personality traits and job characteristics on work behaviors. Job applicants (N = 161) completed personality questionnaires measuring extraversion, neuroticism, achievement motivation, and experience seeking. One and a half years later, supervisors rated the applicants' job performance, and the job incumbents completed questionnaires about skill variety, autonomy, and feedback, work stress, job satisfaction, work self-efficacy, and propensity to leave. LISREL was used to test 15 hypotheses. Perceived feedback mediated the relationship between achievement motivation and job performance. Extraversion predicted work self-efficacy and job satisfaction. Work stress mediated the relationship between neuroticism and job satisfaction. Job satisfaction and experience seeking were related to propensity to leave. Autonomy, skill variety, and feedback were related to job satisfaction

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

Lokomat: Automated electromechanical gait training in neurological patients

Neurological disorders such as stroke and (incomplete) spinal cord injury (SCI) usually lead to difficulties in performing locomotor activities, such as walking or climbing stairs. Therefore, an important part of rehabilitation programs is aimed at restoration of gait function. To improve walking ability it seems important to include task-specific repetitive training with focus on higher intensities of walking practice. These concepts have lead to the development of various automated electromechanical gait-training devices, such as the Lokomat, which assist walking practice. Although it is claimed that such devices may be highly beneficial owing to the intense practice possible in non-ambulatory patients, scientific evidence which could justify their relatively high cost is scarce. Recently, within our research institute in collaboration with the Rehabilitation Centre Amsterdam, we have started a randomized controlled clinical trial investigating the effectiveness of Lokomat-training in patients after stroke and SCI on gait performance, quality of life and neuromuscular and cardiovascular properties. This lecture will give an overview on the existing literature concerning the efficacy of electromechanical assisted training for walking and the concepts which would favor the use of these devices will be discussed. In addition, developments and preliminary results from our study will be presented and discussed

Reliability and validity of the extended wheelchair circuit in persons with spinal cord injury

To evaluate the reliability and validity of the extended Wheelchair Circuit fifteen dependent subjects with Spinal Cord Injuries performed the extended Wheelchair Circuit two times with 9.3 ± 11.3 days between the trials. Test-retest reliability and validity were calculated for the three outcome measures: ability score, the performance time score and the physical strain score. Validity was assessed by analyzing the scores of the Wheelchair Circuit on age, lesion level and completeness of the lesion. The intraclass correlation coefficients of the Wheelchair Circuit were 0.94 for ability score, 0.99 for performance time score and 0.82 for physical strain score at confidence level p<0.05. Validity was good using lesion level on both ability and performance time scores: a significant difference between scores of persons with para- and tetraplegia was found (p<.05). Age did not correlate with any of the scores and also completeness of the lesion was no factor for wheelchair skill performance. Comparing the original Wheelchair Circuit with the ability score of the extended Wheelchair Circuit showed that the variability and discrimination between subjects and groups improved, but floor and ceiling effect remained. The Extended Wheelchair Circuit is a reliable research tool. The ability and performance time score are valid scores. Further research should focus on validity (especially of the physical strain score) and floor and ceiling-effect reducing tasks using a larger and more varied study population

Energy expenditure of stroke patients during upright standing

Purpose: To study the energy expenditure needed for balance control of stroke patients during upright standing, and to determine the relationship between energy expenditure and measures of balance control and muscle activity. Methods: Ten stroke patients and twelve healthy controls performed four upright standing tasks; one without and three with balance perturbations. Energy expenditure was assessed using a pulmonary gas measurement system. Conventional and dynamic balance measures were calculated from center of pressure time series, obtained with a force plate. Muscle activity of the ankle plantar flexors and dorsal flexors was measured using electromyography. Results: On average, energy expenditure during standing was 125% higher in stroke patients. Challenging balance caused a significant increase in energy expenditure (21-52%) for both groups, but no significant interaction (group x condition) was found. Balance control was impaired and muscle activity was higher in stroke patients in all standing conditions. Significant, though moderate to low, correlations were found between energy expenditure and measures of balance control and muscle activity. Conclusion: This study shows that the increased effort for maintaining balance can have a clinically relevant effect on energy expenditure of stroke patients. Besides balance control, other factors responsible for the increased energy expenditure during upright standing in stroke patients should be explored

Effect and process evaluation of implementing patient monitoring in spinal cord injury rehabilitation

The purpose of this study was to evaluate the implementation of standardized physical and functional tests to individually monitor patients with a spinal cord injury (SCI) in 8 rehabilitation centers and to analyze enablers and barriers of the implementation process. A prospective effect- and process evaluation was performed. Team members responded to mailed questionnaires at the start (n=115) and end (n=82) of the one-year implementation period. Furthermore, a questionnaire was administered to managers (n=8), coordinators (n=8) and 32 persons with SCI in 4 centers. Outcome of the effect evaluation was the phase of implementation of standardized testing in each center. The process evaluation analyzed enablers and barriers of the implementation process. After a year of implementation, half of the centers shifted to higher implementation phases. None of the centers was classified in the highest phase. Enablers were the positive attitude of the team members regarding standardized testing and an encouraging local coordinator. Most important barrier was lack of time to implement standardized testing. It can be concluded that there is a large support for implementing standardized tests to monitor functioning of patients with SCI. During a year a positive shift was visible in the extent of implementation. Successful implementation of patient monitoring requires substantial amounts of time and effort of the rehabilitation centers involved

Relation between shoulder proprioception, kinematics and pain after stroke

Purpose: To identify a possible relationship between chronic Post-Stroke Shoulder Pain (PSSP), scapular resting pose and shoulder proprioception. Methods: A total of 21 inpatients with stroke and 10 healthy control subjects were included and kinematics and proprioception of both shoulders were measured. Results: The contralateral (i.e. paretic) shoulder of patients with PSSP showed more scapular lateral rotation and larger errors on proprioception tests compared to both patients without PSSP and control subjects. Additionally, the contralateral shoulder of patients with deteriorated proprioception showed more scapular lateral rotation compared to control subjects whereas their ipsilateral (i.e. unaffected) shoulder showed more scapular lateral rotation when compared to both control subjects and patients with good proprioception. Conclusions: A clear relation between affected shoulder kinematics, affected proprioception and PSSP was found. In determining the risk of developing PSSP, attention should be paid to a patients shoulder proprioception and kinematics. If both are altered after stroke, this could worsen the initial pathology or cause secondary pathologies and thus initiate a vicious circle of repetitive soft tissue damage leading to chronic PSSP. Additionally, more attention should be paid to the ipsilateralshoulder since it could be used in determining the risk of developing PSSP in the contralateral shoulder

Absence of Direct Delivery for Single Transmembrane Apical Proteins or Their “Secretory” Forms in Polarized Hepatic Cells

The absence of a direct route to the apical plasma membrane (PM) for single transmembrane domain (TMD) proteins in polarized hepatic cells has been inferred but never directly demonstrated. The genes encoding three pairs of apical PM proteins, whose extracellular domains are targeted exclusively to the apical milieu in Madin-Darby canine kidney cells, were packaged into recombinant adenovirus and delivered to WIF-B cells in vitro and liver hepatocytes in vivo. By immunofluorescence and pulse-chase metabolic labeling, we found that the soluble constructs were overwhelmingly secreted into the basolateral milieu, which in vivo is the blood and in vitro is the culture medium. The full-length proteins were first delivered to the basolateral surface but then concentrated in the apical PM. Our results imply that hepatic cells lack trans-Golgi network (TGN)-based machinery for directly sorting single transmembrane domain apical proteins and raise interesting questions about current models of PM protein sorting in polarized and nonpolarized cells