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Vergroesen P.-P.A.,VU University Amsterdam | Bochynska A.I.,University of Twente | Bochynska A.I.,Radboud University Nijmegen | Emanuel K.S.,VU University Amsterdam | And 4 more authors.
Spine | Year: 2015

Study Design. A biodegradable glue was biomechanically tested for annulus closure using nondegenerated goat intervertebral discs. Ultimate strength and endurance tests were performed using native and punctured discs as positive and negative controls, respectively. Objective. The aim of this study was to investigate the feasibility and biomechanical properties of a biodegradable glue for annulus closure. Summary of Background Data. There is an unmet clinical need for annulus closure techniques. Isocyanate-terminated tissue glues show potential because they adhere to annulus tissue, have an elastic modulus similar to the annulus, and show limited cytotoxicity to human annulus fibrosus cells. Methods. Three biomechanical tests were performed divided in 2 parts: part 1: ultimate strength tests comparing native, punctured (2.4-mm needle), and glued caprine intervertebral discs (n = 11 per group); part 2: 10 discs per group were subjected to a 10-day ex vivo endurance test of 864,000 load cycles, followed by ultimate strength tests. Outcome parameters include the restoration of strength after puncture, reduction of herniation in the endurance test, and conservation of glue strength after endurance testing. Results. Part 1: The glue partially restored subsidence to failure and yield strength/ultimate strength ratio of intervertebral discs. Part 2: During endurance testing, 40% of punctured discs failed compared with none of the glued discs. Endurance testing did not affect glue strength, and pooling of ultimate strength tests showed that the glue restored ultimate strength, work to failure, and yield strength/ultimate strength to 79%, 75%, and 119% of native values, respectively. Conclusion. A biodegradable isocyanate-terminated glue increases the force at which nucleus protrusion occurs, and it limits herniations during endurance or ultimate strength tests. Biomechanical tests in a bioreactor provide a low-cost assessment for annulus repair strategies; however, the clinical efficacy needs to be further addressed using long-term in vivo studies. © 2015, Wolters Kluwer Health, Inc.

Blaauboer M.E.,VU University Amsterdam | Blaauboer M.E.,TNO | Boeijen F.R.,VU University Amsterdam | Emson C.L.,Kinemed Inc. | And 6 more authors.
Matrix Biology | Year: 2014

Lung fibrosis is characterized by excessive deposition of extracellular matrix. This not only affects tissue architecture and function, but it also influences fibroblast behavior and thus disease progression. Here we describe the expression of elastin, type V collagen and tenascin C during the development of bleomycin-induced lung fibrosis. We further report in vitro experiments clarifying both the effect of myofibroblast differentiation on this expression and the effect of extracellular elastin on myofibroblast differentiation. Lung fibrosis was induced in female C57Bl/6 mice by bleomycin instillation. Animals were sacrificed at zero to five weeks after fibrosis induction. Collagen synthesized during the week prior to sacrifice was labeled with deuterium. After sacrifice, lung tissue was collected for determination of new collagen formation, microarray analysis, and histology. Human lung fibroblasts were grown on tissue culture plastic or BioFlex culture plates coated with type I collagen or elastin, and stimulated to undergo myofibroblast differentiation by 0-10ng/ml transforming growth factor (TGF)β1. mRNA expression was analyzed by quantitative real-time PCR.New collagen formation during bleomycin-induced fibrosis was highly correlated to gene expression of elastin, type V collagen and tenascin C. At the protein level, elastin, type V collagen and tenascin C were highly expressed in fibrotic areas as seen in histological sections of the lung. Type V collagen and tenascin C were transiently increased. Human lung fibroblasts stimulated with TGFβ1 strongly increased gene expression of elastin, type V collagen and tenascin C. The extracellular presence of elastin increased gene expression of the myofibroblastic markers α smooth muscle actin and type I collagen.The extracellular matrix composition changes dramatically during the development of lung fibrosis. The increased levels of elastin, type V collagen and tenascin C are probably the result of increased expression by fibroblastic cells; reversely, elastin influences myofibroblast differentiation. This suggests a reciprocal interaction between fibroblasts and the extracellular matrix composition that could enhance the development of lung fibrosis. © 2013 International Society of Matrix Biology.

Ruiz-Zapata A.M.,VU University Amsterdam | Ruiz-Zapata A.M.,MOVE Research Institute Amsterdam | Kerkhof M.H.,Kennemer Gasthuis Hospital | Zandieh-Doulabi B.,VU University Amsterdam | And 3 more authors.
International Urogynecology Journal and Pelvic Floor Dysfunction | Year: 2013

Introduction and hypothesis Little is known about dynamic cell-matrix interactions in the context of pathophysiology and treatments for pelvic organ prolapse (POP). This study sought to identify differences between fibroblasts from women with varying degrees of prolapse in reaction to mechanical stimuli and matrix substrates in vitro. Methods Fibroblasts from the vaginal wall of three patients with POP Quantification (POP-Q) system stages 0, II, and IV were stretched on artificial polymer substrates either coated or not coated with collagen I. Changes in morphology and anabolic/catabolic compounds that affect matrix remodelling were evaluated at protein-and geneexpression levels. Statistical analysis was performed using one-way analysis of variance (ANOVA), followed by Tukey-Kramer's post hoc test. Results POP fibroblasts show delayed cell alignment and lower responses to extracellular matrix remodelling factors at both enzymatic-and gene-expression levels compared with healthy fibroblasts. Conclusion POP fibroblasts, when compared with healthy cells, show differential mechanoresponses on two artificial polymer substrates. This should be taken into account when designing or improving implants for treating POP. © 2013 The Author(s).

Webb R.,Merri Community Health Services | Cofre Lizama L.E.,MOVE Research Institute Amsterdam | Galea M.P.,Royal Melbourne Hospital
Evidence-based Complementary and Alternative Medicine | Year: 2013

Objective. To investigate the effects of Feldenkrais Method classes on gait, balance, function, and pain in people with osteoarthritis. Design. Prospective study with pre-/postmeasures. Setting. Community. Participants. Convenience sample of 15 community-dwelling adults with osteoarthritis (mean age 67 years) attending Feldenkrais Method classes. Intervention. Series of Feldenkrais Method classes, two classes/week for 30 weeks. Main outcome measures: Western Ontario and McMaster Universities osteoarthritis scale, Human Activity Profile, stair climbing test, 6-minute walk test, timed up-and-go test, Four Square Step Test (4SST), gait analysis, and assessment of quality of life (AQoL). Results. Participants improved on the 4SST and on some gait parameters. They also reported a greater ease of movement. Conclusions. A 30-week series of Feldenkrais classes held twice per week was feasible in the community setting. The lessons led to improvements in performance of the four square step test and changes in gait. © 2013 Robert Webb et al.

PubMed | VU University Amsterdam, MOVE Research Institute Amsterdam and University Childrens Hospital Basle
Type: Journal Article | Journal: PloS one | Year: 2016

To increase knee range of motion and improve gait in children with spastic paresis (SP), the semitendinosus muscle (ST) amongst other hamstring muscles is frequently lengthened by surgery, but with variable success. Little is known about how the pre-surgical mechanical and morphological characteristics of ST muscle differ between children with SP and typically developing children (TD). The aims of this study were to assess (1) how knee moment-angle characteristics and ST morphology in children with SP selected for medial hamstring lengthening differ from TD children, as well as (2) how knee moment-angle characteristics and ST morphology are related. In nine SP and nine TD children, passive knee moment-angle characteristics and morphology of ST (i.e. fascicle length, muscle belly length, tendon length, physiological cross-sectional area, and volume) were assessed by hand-held dynamometry and freehand 3D ultrasound, respectively. At net knee flexion moments above 0.5 Nm, more flexed knee angles were found for SP compared to TD children. The measured knee angle range between 0 and 4 Nm was 30% smaller in children with SP. Muscle volume, physiological cross-sectional area, and fascicle length normalized to femur length were smaller in SP compared to TD children (62%, 48%, and 18%, respectively). Sixty percent of the variation in knee angles at 4 Nm net knee moment was explained by ST fascicle length. Altered knee moment-angle characteristics indicate an increased ST stiffness in SP children. Morphological observations indicate that in SP children planned for medial hamstring lengthening, the longitudinal and cross-sectional growth of ST muscle fibers is reduced. The reduced fascicle length can partly explain the increased ST stiffness and, hence, a more flexed knee joint in these SP children.

Balemans A.C.J.,MOVE Research Institute Amsterdam | Balemans A.C.J.,VU University Amsterdam | Van Wely L.,MOVE Research Institute Amsterdam | Van Wely L.,VU University Amsterdam | And 4 more authors.
Developmental Medicine and Child Neurology | Year: 2015

Aim: The aim of this study was to determine the longitudinal associations among fitness components and between fitness and mobility capacity in children with cerebral palsy (CP). Method: Forty-six children (26 males, 20 females; mean age 9y 7mo [SD 1y 8mo]) with a bilateral (n=24) or a unilateral spastic CP (n=22) participated in aerobic and anaerobic fitness measurements on a cycle ergometer and isometric muscle strength tests (Gross Motor Function Classification System [GMFCS] level I [n=26], level II [n=12], level III [n=8]). Mobility capacity was assessed with the gross motor function measure (GMFM) and a walking capacity test. Associations over longitudinal measurements (three or four measurements over 1y) were determined since longitudinal data allow a more accurate estimation. The associations were determined using a mixed model with fixed effects (mobility capacity as dependent variables and fitness components as independent variables) and a random intercept. Results: In children with bilateral CP, changes in aerobic fitness were associated with changes in anaerobic fitness (p<0.001), and changes in aerobic fitness showed an association with changes in muscle strength (p<0.05). Anaerobic fitness was not associated with muscle strength. No associations between fitness components were found in unilateral CP. Anaerobic fitness and muscle strength were significant determinants for GMFM and walking capacity in bilateral but not in unilateral CP. Interpretation: The longitudinal associations between aerobic and anaerobic fitness and mobility indicate that increasing either aerobic or anaerobic fitness is associated with improvements in mobility in children with bilateral CP. While increasing anaerobic fitness might be beneficial for mobility capacity in children with bilateral CP, this is less likely for children with unilateral CP. © 2015 Mac Keith Press.

Huijing P.A.,VU University Amsterdam | Benard M.R.,VU University Amsterdam | Benard M.R.,Move Research Institute Amsterdam | Harlaar J.,Move Research Institute Amsterdam | And 2 more authors.
BMC Musculoskeletal Disorders | Year: 2013

Background: In spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment. Methods. For a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation. Results: SCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important.Using a new estimate for position at the talocrural joint (the difference between GM muscle-tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths. Conclusions: In SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot. © 2013 Huijing et al.; licensee BioMed Central Ltd.

Maas J.C.,MOVE Research Institute Amsterdam | Huijing P.A.,VU University Amsterdam | Dallmeijer A.J.,MOVE Research Institute Amsterdam | Harlaar J.,VU University Amsterdam | And 2 more authors.
Journal of Electromyography and Kinesiology | Year: 2015

Purpose: To determine the effects of decreased ankle-foot dorsiflexion (A-Fdf) range of motion (ROM) on gait kinematics in children with spastic cerebral palsy (SCP). Methods: All participants were children with spastic cerebral palsy (n= 10) who walked with knee flexion in midstance. Data were collected over 2-5 sessions, at 3-monthly intervals. A-Fdf ROM was quantified using a custom-designed hand-held ankle dynamometer that exerted 4. Nm at the ankle. Ankle-foot and knee angles during gait were quantified on sagittal video recordings. Linear regression (cross-sectional analysis) and General Estimation Equation analysis (longitudinal analysis) were performed to assess relationships between (change in) A-Fdf ROM and (change in) ankle-foot and knee angle during gait. Results: Cross-sectional analysis showed a positive relationship between A-Fdf ROM and both ankle-foot angle in midstance and terminal swing. Longitudinal analysis showed a positive relationship between individual decreases in A-Fdf ROM and increases of knee flexion during gait (lowest knee angle in terminal stance and angle in terminal swing). Conclusion: For this subgroup of SCP children, our results indicate that while changes in ankle angles during gait are unrelated to changes in A-Fdf ROM, changes in knee angles are related to changes in A-Fdf ROM. © 2015.

PubMed | MOVE Research Institute Amsterdam
Type: Journal Article | Journal: Journal of biomechanics | Year: 2016

Previously it has been shown that constraining step width in gait coincides with decreased trunk displacements. Conversely, external stabilization of the upper body in gait coincides with decreased step width, but this may in part be due to changes in passive dynamics of the leg. In the present study, trunk kinematics during gait were constrained without external stabilization by using an orthosis, to investigate whether step width and dynamic gait stability in the ML direction are changed in relation to trunk kinematics. Nine healthy young adults walked on a treadmill at three different speeds with no intervention and while wearing a thoracolumbar orthosis. Based on marker trajectories, trunk COM displacement, body COM displacement and velocity, step width, and margin-of-stability in ML direction were calculated. The results showed that the orthosis significantly reduced trunk and body COM displacements. As hypothesized, the restriction of trunk movement coincided with significantly decreased step width, while the margin-of-stability was not affected. These findings indicate that, when trunk movements are constrained, humans narrow step width, while maintaining a constant margin-of-stability. In conclusion, the present results in combination with previous work imply that in gait a reciprocal coupling between trunk kinematics and foot placement in the frontal plane subserves control of stability in the frontal plane.

PubMed | MOVE Research Institute Amsterdam
Type: | Journal: Gait & posture | Year: 2016

Successful execution of motor tasks requires an integration of the perception of ones physical abilities and the perception of the task itself. Physical and cognitive decline associated with ageing may lead to misjudgments of these perceived and actual abilities and possibly to errors that may lead to balance loss. We aimed to directly quantify the degree to which older adults misjudge their actual gait ability. Twenty-seven older adults participated and were instructed to walk on a narrow path projected on a treadmill. We tested two paradigms to estimate the participants perceived gait ability: a path width manipulation, in which participants had to indicate the smallest path width that they could walk on without stepping outside or losing balance (at given speed), and a treadmill speed manipulation, in which they had to indicate the maximum speed that they could use at a given path width. We determined their actual ability as the probability of stepping inside the path over a range of path widths and speeds. The path width paradigm seemed suitable for evaluating self-perception of actual gait ability and revealed that participants appeared to show a range of misjudgment towards either over- or underestimating their actual abilities. Better abilities appeared not associated with better judgment. Direct quantification of the degree of misjudgment provides insight in the interplay between cognition and physical abilities and can be of added value towards prevention of falls and promotion of healthy ageing.

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