References of "Garraux, Gaëtan"
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See detailEffects of α-synuclein levels on cerebral synaptic function: Validation of a novel PET radioligand for the early diagnosis of Parkinson’s disease
Tarragon Cros, Ernesto ULg; Ferrara, André ULg; Tirelli, Ezio ULg et al

Poster (2015, January 27)

Background In Parkinson’s disease, converging evidence supports a pathogenic role for excessive α–synuclein accumulation in synaptic terminals that may propagate back to the soma of vulnerable nerve cells ... [more ▼]

Background In Parkinson’s disease, converging evidence supports a pathogenic role for excessive α–synuclein accumulation in synaptic terminals that may propagate back to the soma of vulnerable nerve cells such as neurons in the substantia nigra pars compacta. The resulting loss of dopaminergic terminals in the striatum can be demonstrated in vivo using 18F-Dopa-PET (positron emission tomography). However, there’s currently no validated biomarker of the progressive synaptic dysfunction in other vulnerable areas such as the cerebral cortex. Goal In this longitudinal study, we will test the hypothesis that the loss of synaptic terminals in a mouse model of excessive α–synuclein accumulation can be demonstrated in vivo before the occurrence of behavioural disturbances using 18F-UCB-H, a new PET biomarker developed at CRC. We will also test if this new imaging modality is sensitive enough to study the effect of a disease modifying therapy such as chronic physical exercise. Methods We will use microPET for the in vivo quantification of 18F-UCB-H brain uptake in 16 wild type animals and 16 transgenic (Tg) mice overexpressing human α–syn under the mThy1 promotor every 2 months. Data will be validated against post-mortem analyses after the last PET study. Predictions We predict decreased tracer uptake over time in the basal ganglia and cerebral cortex in Tg mice as compared with WT animals. Also, we predict a relationship between 18F-UCB-H uptake levels in basal ganglia and cerebral cortex and progressive alterations in both motor and cognitive functions, respectively. Further, we also expect that chronic exercise will slow down both motor and cognitive disturbances, as well as the rate of 18F-UCB-H brain uptake decreases. Conclusion If 18F-UCB-H PET proves to be a valid biomarker for the early detection of α–synuclein accumulation in the pre-clinical model of PD, the methods will tested on human clinical populations. [less ▲]

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See detailDevelopment and validation of an accelerometer-based method for quantifying gait events
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

in Medical Engineering & Physics (2015)

An original signal processing algorithm is presented to automatically extract, on a stride-by-stride basis, four consecutive fundamental events of walking, heel strike (HS), toe strike (TS), heel-off (HO ... [more ▼]

An original signal processing algorithm is presented to automatically extract, on a stride-by-stride basis, four consecutive fundamental events of walking, heel strike (HS), toe strike (TS), heel-off (HO), and toe-off (TO), from wireless accelerometers applied to the right and left foot. First, the signals recorded from heel and toe three-axis accelerometers are segmented providing heel and toe flat phases. Then, the four gait events are defined from these flat phases. The accelerometer-based event identification was validated in seven healthy volunteers and a total of 247 trials against reference data provided by a force plate, a kinematic 3D analysis system, and video camera. HS, TS, HO, and TO were detected with a temporal accuracy ± precision of 1.3 ms ± 7.2 ms, ‒4.2 ms ± 10.9 ms, ‒3.7 ms ± 14.5 ms, and ‒1.8 ms ± 11.8 ms, respectively, with the associated 95% confidence intervals ranging from ‒6.3 ms to 2.2 ms. It is concluded that the developed accelerometer-based method can accurately and precisely detect HS, TS, HO, and TO, and could thus be used for the ambulatory monitoring of gait features computed from these events when measured concurrently in both feet. [less ▲]

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See detailDevelopment and validation of a 3D kinematic-based method for determining gait events during overground walking
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Denoël, Vincent ULg et al

in IEEE International Conference on 3D Imaging (IC3D) (2014, December 09)

A new signal processing algorithm is developed for quantifying heel strike (HS) and toe-off (TO) event times solely from measured heel and toe coordinates during overground walking. It is based on a rough ... [more ▼]

A new signal processing algorithm is developed for quantifying heel strike (HS) and toe-off (TO) event times solely from measured heel and toe coordinates during overground walking. It is based on a rough estimation of relevant local 3D position signals. An original piecewise linear fitting method is applied to these local signals to accurately identify HS and TO times without the need of using arbitrary experimental coefficients. We validated the proposed method with nine healthy subjects and a total of 322 trials. The extracted temporal gait events were compared to reference data obtained from a force plate. HS and TO times were identified with a temporal accuracy ± precision of 0.3 ms ± 7.1 ms, and –2.8 ms ± 7.2 ms in comparison with reference data defined with a force threshold of 10 N. This algorithm improves the accuracy of the HS and TO detection. Furthermore, it can be used to perform stride-by-stride analysis during overground walking with only recorded heel and toe coordinates. [less ▲]

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See detailMapping track density changes in nigrostriatal and extranigral pathways in Parkinson's disease
Ziegler, Erik ULg; Rouillard, Maud; André, Elodie et al

in NeuroImage (2014), 99

Highlights First whole-brain probabilistic tractography study in Parkinson's disease High quality diffusion-weighted images (120 gradient directions, b = 2500 s/mm2) Voxel-based group analysis comparing ... [more ▼]

Highlights First whole-brain probabilistic tractography study in Parkinson's disease High quality diffusion-weighted images (120 gradient directions, b = 2500 s/mm2) Voxel-based group analysis comparing early-stage patients and controls Abnormal reconstructed track density in the nigrostriatal pathway and brainstem Track density also increased in limbic and cognitive circuits. [less ▲]

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See detailValidation des paramètres de marche par un système accélérométrique (Locométrix*) à l'aide d'un système opto-électronique 3D (Coda Motion )
GILLAIN, Sophie ULg; Schwartz, Cédric ULg; Boutaayamou, Mohamed ULg et al

in Gériatrie et Psychologie Neuropsychiatrie du Vieillissement (2014), 12(supplément 3),

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See detailQuantitative multi-parameter mapping in parkinson’s disease: preliminary results
Rouillard, Maud ULg; D'Ostilio, Kevin ULg; Albinet, Cedric et al

Poster (2014, May)

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See detailBiased binomial assessment of cross-validated estimation of classification accuracies illustrated in diagnosis predictions
Noirhomme, Quentin ULg; Lesenfants, Damien ULg; Gomez, Francisco et al

in NeuroImage: Clinical (2014), 4

Multivariate classification is used in neuroimaging studies to infer brain activation or in medical applications to infer diagnosis. Their results are often assessed through either a binomial or a ... [more ▼]

Multivariate classification is used in neuroimaging studies to infer brain activation or in medical applications to infer diagnosis. Their results are often assessed through either a binomial or a permutation test. Here, we simulated classification results of generated random data to assess the influence of the cross-validation scheme on the significance of results. Distributions built from classification of random data with crossvalidation did not follow the binomial distribution. The binomial test is therefore not adapted. On the contrary, the permutation test was unaffected by the cross-validation scheme. The influence of the crossvalidation was further illustrated on real-data from a brain–computer interface experiment in patients with disorders of consciousness and from an fMRI study on patients with Parkinson disease. Three out of 16 patients with disorders of consciousness had significant accuracy on binomial testing, but only one showed significant accuracy using permutation testing. In the fMRI experiment, the mental imagery of gait could discriminate significantly between idiopathic Parkinson’s disease patients and healthy subjects according to the permutation test but not according to the binomial test. Hence, binomial testing could lead to biased estimation of significance and false positive or negative results. In our view, permutation testing is thus recommended for clinical application of classification with cross-validation. [less ▲]

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See detailValidation des paramètres de marche par un système accélérométrique (Locométrix) à l’aide d’un système opto-électronique 3D (Coda Motion)
GILLAIN, Sophie ULg; Schwartz, C; Dramé, M et al

in Cahiers de l'Année Gérontologique (Les) (2014), 2(23), 724-73

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See detail3D analysis of gait using accelerometer measurements
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

Scientific conference (2013, November 07)

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See detailEVALUATION OF α-SYNUCLEIN AS BIOMARKER OF PARKINSON'S DISEASE
Napp, Aurore ULg; Garraux, Gaëtan ULg; Servais, Anne-Catherine ULg et al

Conference (2013, October 17)

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See detailStrength improvement after 3months of resistance training among Parkinson's disease patients
Demonceau, Marie ULg; rodriguez de la cruz, carlos; NAVEAU, Florence ULg et al

in Annals of Physical and Rehabilitation Medicine (2013, October), 56(s1), 196

Objectives.– To assess the feasibility and the effects of a strengthening program for people with Parkinson's disease (PD). Methods.– Fourteen patients with Hoehn and Yahr stage [1] < III of PD were ... [more ▼]

Objectives.– To assess the feasibility and the effects of a strengthening program for people with Parkinson's disease (PD). Methods.– Fourteen patients with Hoehn and Yahr stage [1] < III of PD were allocated to either 24 sessions of strength training (ST group; n = 8) or to a control group (C group; n = 6) for 3 months. Concentric knee muscle strength and a maximal cycling incremental test were performed at baseline and after training. Training consisted of progressive resistive exercises on leg press, leg extension, leg curl, between 50 and 80% of 1RM and was completed by non-instrumented exercises for trunk and upper limbs muscles. Anxiety, depression and quality of life were assessed using questionnaires. An Anova for repeated measures was used for statistical analysis. Results.– Six patients of the ST group (75%) fully completed the program. There were significant “group by time” effects for all knee muscles strength measures of less involved side (P < 0.05). A significant “group by time” effect was also found for knee flexors of the most involved side, but only at angular speed of 180°/s (P = 0.03). Patients of ST group also increased maximal aerobic power (+13%) whereas patients of C group decreased their performances (–9%; “group by time” effect, P = 0.04). No changes in anxiety, depression or quality of life could be highlighted. Conclusions.– The increase of some strength measures in ST group showed that progressive strength training counteracts strength decrease among people with Parkinson's disease. Strengthening also had a positive effect on maximal aerobic power. [less ▲]

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See detailEffects of 3 months of aerobic training on fitness of Parkinson's disease patients
Demonceau, Marie ULg; rodriguez de la Cruz, carlos; kalimira, kinja et al

in Annals of Physical and Rehabilitation Medicine (2013)

Objectives.– To assess the effects of an aerobic training for people with Parkinson's disease (PD). Methods.– Fourteen patients with Hoehn & Yahr stage [1] < III of PD were allocated to either 3 months of ... [more ▼]

Objectives.– To assess the effects of an aerobic training for people with Parkinson's disease (PD). Methods.– Fourteen patients with Hoehn & Yahr stage [1] < III of PD were allocated to either 3 months of twice-weekly aerobic training (AT group; n = 8), or a control group (C group; n = 6). AT consisted in progressive stationary bike training between 50 and 70% of peak work load (PWL). Maximal incremental test on a cycloergometer was performed before and after rehabilitation. Anxiety, depression and quality of life were assessed using questionnaires. An Anova for repeated measures was used for statistical analysis. Results.– There was a significant “group by time” effect for peak work load (+21% for patients of AT group vs –9% for people of C group). Heart rate 2 minutes after test completion was also significantly decreased in AT group (post hoc analysis, P < 0.01). Patients of AT group also increased their ratio of predicted VO2 peak (+17%) but in a non-significant way. No significant changes in anxiety, depression or quality of life could be highlighted. Conclusions.– This study showed significant improvement of PWL and faster recovery in patients with PD of the AT. Significant effect on VO2 peak could need a more intense training program. [less ▲]

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See detailImpaired automatic and unconscious motor processes in Parkinson's disease
D'Ostilio, Kevin ULg; CREMERS, Julien ULg; DELVAUX, Valérie ULg et al

in Scientific Reports (2013)

While it is increasingly recognized that voluntary movements are produced by an interaction between conscious and unconscious processes, the role of the latter in Parkinson’s disease has received little ... [more ▼]

While it is increasingly recognized that voluntary movements are produced by an interaction between conscious and unconscious processes, the role of the latter in Parkinson’s disease has received little attention to date. Here, we administered a subliminal masked prime task to 15 Parkinson’s disease patients and 15 age-matched healthy elderly subjects. Compatibility effects were examined by manipulating the direction of the arrows and the interstimuli interval. Analysis of the positive compatibility effect revealed performance differences between the most and the least affected hand in Parkinson’s disease patients. Additionally, patients did not show the same tendency toward a negative compatibility effect as compared to elderly controls. These novel findings provide evidence supporting the role of basal ganglia circuits in controlling the balance between automatic motor response facilitation and inhibition. [less ▲]

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See detailValidation of an accelerometer-based approach to quantify gait events
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Stamatakis, Julien et al

Poster (2013, June)

Researchers rarely provide solid performance and validation information about their acceleometer-based approaches to human gait analysis. We present here a novel signal processing and analysis algorithm ... [more ▼]

Researchers rarely provide solid performance and validation information about their acceleometer-based approaches to human gait analysis. We present here a novel signal processing and analysis algorithm that automatically extracts four consecutive fundamental events of walking: heel strike (HS), toe strike (TS), heel off (HO), and toe off (TO). In addition, we validate this accelerometer-based technique by comparing these extracted gait events with those obtained by a kinematic 3D analysis system and a force plate, used as gold standards. [less ▲]

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See detailLes troubles du contrôle des impulsions associés au traitement dopaminergique substitutif antiparkinsonien
DEPIERREUX, Frédérique ULg; CREMERS, Julien ULg; SKAWINIAK, Eva ULg et al

in Revue Médicale de Liège (2013), 68(mai-juin), 221-225

Summary : In some patients, impulse control behaviours can be triggered by dopaminergic replacement therapy, particularly dopamine agonist drugs: hobbyism, punding (stereotyped behaviours), compulsive ... [more ▼]

Summary : In some patients, impulse control behaviours can be triggered by dopaminergic replacement therapy, particularly dopamine agonist drugs: hobbyism, punding (stereotyped behaviours), compulsive buying, binge eating disorder, pathological gamgling, hypersexuality, hedonistic homeostatic dysregulation syndrome ... The pathogenesis of these behaviours is not well understood, but likely involves aberrant changes in the dopaminergic pathways that mediate motivation i.e., a dopaminergic “overdose” in meso-cortico-limbic circuits. An early diagnosis is difficult, but mandatory to prevent the occurrence of devastating familial, marital, professional, socio-economic, medical and medico-legal consequences. Their management is not yet well standardized. Patients and caregivers should be warned about impulse control behaviours before starting dopamine agonists and monitoring for such behaviours while on therapy is requested. [less ▲]

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