Biomedical subjects

D De Clercq

Publications and source records attributed to D De Clercq.

At least 19 recordsLinked to original sources

PubMed2006

Kinematics of the transition between walking and running when gradually changing speed.

The purpose of this study was to examine kinematics of the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered with a constant acceleration of 0.1 m s(-2), respectively -0.1 m s(-2). Thirteen women (height: 168.9+/-3.36 cm) performed gait transitions on a motor-driven treadmill. WRT-speed was 2.16+/-0.12 m s(-1), RWT-speed 2.19+/-0.12 m s(-1). Kinematics were examined in the range from eight steps before to eight steps after transition in order to identify the possible occurrence of a transition process to facilitate the actual realization of transition. A transition step in which the main changes from one gait to another are realized is present in WRT and RWT. Despite this clear discontinuity, a transition process also appeared in both transitions. In the WRT, transition was prepared and kinematic adaptations were found in the last swing before transition leading to altered landing conditions. During RWT posttransition changes were observed and RWT was only completed after reorientation of the trunk in the first walking stride after transition. A noteworthy finding was that spatiotemporal (presence of a flight phase), kinematic (knee flexion) and energetic (kinetic and gravitational potential energy fluctuating in-phase versus out-of-phase) criteria to define transition stride correspond to each other. Furthermore, a functional interlimb asymmetry was recognized as a unique characteristic of the transition stride, offering a fourth way of identifying the transition stride.

Acceleration↗

PubMed2006

Influence of M. tibialis anterior fatigue on the walk-to-run and run-to-walk transition in non-steady state locomotion.

The purpose of this study was to examine the influence of muscular fatigue of tibialis anterior (TA) on the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered at different constant accelerations (a=0.01, 0.07 and 0.05 ms(-2)). Twenty women (height: 168.9+/-3.36 cm) performed WRTs and RWTs on a motor-driven treadmill, before and after a protocol inducing muscular fatigue of the TA. WRT-speed decreased after TA fatigue whereas RWT-speed did not change except during the intermediate deceleration. Integrated EMG (iEMG) of the activity burst of TA around heel contact was examined in the last steps before transition, the transition step and the first steps after transition. iEMG increased before WRT, then decreased after transition to running. In the RWT the opposite was observed: iEMG increased after RWT, then decreased with decreasing walking speed. After inducing fatigue in the TA, there was a decrease in iEMG in the WRT whereas no influence of fatigue was found on iEMG in the RWT. As a result of TA fatigue, WRT occurred at a lower speed, probably to avoid over-exertion of the TA. This indicates that the TA is a likely determinant of WRT as previously reported. The RWT, on the other hand, was not altered following TA fatigue, which would indicate that WRT and RWT are determined by different factors.

Acceleration↗

PubMed2006

Determination of amiodarone and desethylamiodarone in horse plasma and urine by high-performance liquid chromatography combined with UV detection and electrospray ionization mass spectrometry.

A rapid method for the quantification of amiodarone and desethylamiodarone in animal plasma using high-performance liquid chromatography combined with UV detection (HPLC-UV) is presented. The sample preparation includes a simple deproteinisation step with acetonitrile. In addition, a sensitive method for the quantification of amiodarone and desethylamiodarone in horse plasma and urine using high-performance liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is described. The sample preparation includes a solid-phase extraction (SPE) with a SCX column. Tamoxifen is used as an internal standard for both chromatographic methods. Chromatographic separation is achieved on an ODS Hypersil column using isocratic elution with 0.01% diethylamine and acetonitrile as mobile phase for the HPLC-UV method and with 0.1% formic acid and acetonitrile as mobile phase for the LC-MS/MS method. For the HPLC-UV method, good linearity was observed in the range 0-5 microg ml(-1), and in the range 0-1 microg ml(-1) for the LC-MS/MS method. The limit of quantification (LOQ) was set at 50 and 5 ng ml(-1) for the HPLC-UV method and the LC-MS/MS method, respectively. For the UV method, the limit of detection (LOD) was 15 and 10 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs of the LC-MS/MS method in plasma were much lower, i.e. 0.10 and 0.04 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs obtained for the urine samples were 0.16 and 0.09 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The methods were shown to be of use in horses. The rapid HPLC-UV method was used for therapeutic drug monitoring after amiodarone treatment, while the LC-MS/MS method showed its applicability for single dose pharmacokinetic studies.

Amiodarone↗

PubMed2006

Intravenous amiodarone treatment in horses with chronic atrial fibrillation.

Six horses without underlying cardiac disease were presented because of atrial fibrillation of between 5 and 12 months duration. These horses received an intravenous amiodarone treatment of 5mg/kg/h for 1 h followed by 0.83mg/kg/h for 23h and subsequently 1.9mg/kg/h for 30h. During treatment, clinical signs were monitored and a surface ECG and an intra-atrial electrogram were recorded. Infusion was discontinued when sinus rhythm or side effects occurred. Four horses successfully cardioverted, of which one showed symptoms of hind limb weakness and weight shifting. Two horses did not cardiovert and showed similar side effects. In all horses, side effects disappeared within 6h after termination of treatment. Cardiac side effects, such as pro-arrhythmia, were not seen in any of the horses. Total bilirubin slightly increased in three horses and normalised within four days. It was concluded that amiodarone has the potential to treat naturally occurring chronic atrial fibrillation in horses, although further research is needed to refine the infusion protocol.

Amiodarone↗

PubMed2006

Visual contribution to walking in children with Developmental Coordination Disorder.

BACKGROUND: The motor co-ordination problems of children with Developmental Coordination Disorder (DCD) have been frequently associated with poor visuospatial processing. In order to extend these findings mainly based on fine motor experiments, the present study investigates the contribution of vision to the control of walking in children with DCD. METHODS: Children with DCD (n = 12) walked at their preferred speed on a straight, firm and uncluttered walkway in a condition with normal lighting and in a dark condition. Spatiotemporal gait variables were assessed by means of a three-dimensional ProReflex camera system and compared with the gait pattern of matched, typically developing (TD) children (n = 12). RESULTS: In normal lighting, the gait pattern of both groups was similar, with the exception of subtle differences in the temporal phasing, showing a slightly longer support phase in the children with DCD. In the dark, step frequency and step length were decreased in the children with DCD, resulting in a significantly slower walking velocity. In addition, the medio-lateral excursion of the centre of mass tended to increase in this group. In the TD children, adaptations to the spatiotemporal pattern remained absent. CONCLUSIONS: These results suggest that children with DCD are more dependent on global visual flow information than TD children for the maintenance of balance and the control of velocity during walking. This increased dependency on visual control might be associated with a poorly developed internal sensorimotor model.

Child↗

PubMed2005

Spatiotemporal characteristics of the walk-to-run and run-to-walk transition when gradually changing speed.

The purpose of this study was to examine spatiotemporal parameters of the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered with different constant accelerations. Twenty women (height: 168.9+/-3.36cm) performed three accelerations (0.05, 0.07 and 0.1ms(-2)) and three decelerations (-0.05, -0.07 and -0.1ms(-2)) on a motor-driven treadmill. The transition step in the WRT (first step with a flight phase) and RWT (first step with a double stance phase) occurred at the same speed for all accelerations but these did not occur in the same way. The most striking difference was the presence of a transition step with specific spatiotemporal characteristics in the WRT, whereas this was not observed in the RWT. The transition is not a sudden one-step-event. WRT occurred before transition and consisted of a "pre-transition period" and the transition step whereas RWT occurred after transition and consisted of the transition step and a "post-transition period". Both transition periods were characterized by an exponential evolution of step frequency and step length. Step frequency and step length showed a linear evolution before and after transition. The flight phase of the transition step in the WRT reached a minimum with comparable duration of the last flight phase in the RWT. The flight phase could be considered as an intrinsic dynamical factor of transition. Further research in kinematics, the trajectory of the body centre of mass and energy fluctuations will give more insight in these transitions.

Acceleration↗

PubMed2005

A functional foot type classification with cluster analysis based on plantar pressure distribution during jogging.

The purpose of this study was to establish a reference dataset for peak pressures and pressure-time integrals during jogging, to compare this reference dataset with existing walking data and to develop a foot type classification, all based on plantar pressure data obtained from 215 healthy young adults. The subjects ran at 3.3 m s(-1) over a 16.5 m long running track, with a built-in pressure platform mounted on top of a force platform. Peak pressures, regional impulses and relative regional impulses were measured. These variables were found to be reliable (all intra class correlation coefficients above 0.75) and, except for the heel areas, gender and asymmetry effects could be neglected. Highest peak pressures were found under the heel due to large impact forces during initial contact phase (ICP). In the forefoot, the highest peak pressure was found under the second metatarsal (64.2 +/- 21.1 N cm(-2)). Compared to walking data, overall higher peak pressures and impulses and difference in hallux loading were found during barefoot jogging. Four pressure loading patterns were identified using a K-means cluster analysis, based on the relative regional impulses underneath the forefoot: medial M1 pattern, medial M2 pattern, central pattern and central-lateral pattern. These four pressure loading patterns could help in the functional interpretation of the foot behaviour during the stance phase in slow running.

Adolescent↗

PubMed2005

A prospective study of gait related risk factors for exercise-related lower leg pain.

The purpose of this study was to determine prospectively gait related risk factors for exercise-related lower leg pain (ERLLP) in 400 physical education students. Static lower leg alignment was determined, and 3D gait kinematics combined with plantar pressure profiles were collected. After this evaluation, all sports injuries were registered by the same sports physician during the duration of the study. Forty six subjects developed ERLLP and 29 of them developed bilateral symptoms thus giving 75 symptomatic lower legs. Bilateral lower legs of 167 subjects who developed no injuries in the lower extremities served as controls. Cox regression analysis revealed that subjects who developed ERLLP had an altered running pattern before the injury compared to the controls and included (1) a significantly more central heel-strike, (2) a significantly increased pronation, accompanied with more pressure underneath the medial side of the foot, and (3) a significantly more lateral roll-off. These findings suggest that altered biomechanics play a role in the genesis of ERLLP and thus should be considered in prevention and rehabilitation.

Adolescent↗

PubMed2005

Relationship between gait biomechanics and inversion sprains: a prospective study of risk factors.

This prospective study determined gait related risk factors for inversion sprains in 223 physical education students. Static lower leg alignment was determined, and 3D-kinematics combined with plantar pressure profiles were collected. After evaluation, the same sports physician registered all sports injuries during the next 6-18 months. During this period, 21 subjects had an inversion sprain, one of whom had a bilateral sprain. Twenty-two ankles, 12 left and 10 right comprised the inversion sprain group and both feet of 36 non-injured subjects acted as controls. Comparison of the two groups revealed that the gait of subjects who are at risk of sustaining an inversion sprain had a laterally situated centre of pressure at initial contact. These subjects also showed a mobile foot type at first metatarsal contact, forefoot flat and heel off. In this type the foot is more pronated over a prolonged period and accompanied by more pressure underneath the medial side of the foot and a delayed maximal knee flexion. Resupination is delayed and roll off does not occur across the hallux, but more laterally, probably because of the diminished support at the first metatarsophalangeal joint. Total foot contact time was also longer in the inversion sprain group compared with controls. The findings of this study suggest that effective prevention and rehabilitation of inversion sprains should include attention to gait patterns and adjustments of foot biomechanics.

Adolescent↗

PubMed2005

Temporal characteristics of foot roll-over during barefoot jogging: reference data for young adults.

The purpose of this study was to establish a representative reference dataset for temporal characteristics of foot roll-over during barefoot jogging, based on plantar pressure data collected from 220 healthy young adults. The subjects ran at 3.3 ms-1 over a 16.5 m long running track, having a built-in pressure platform mounted on a force platform. The initial contact, final contact, time to peak pressure and the duration of contact at the lateral and medial heel, metatarsal heads I to V and the hallux were measured. Temporal plantar pressure variables were found to be reliable (93% of ICC coefficients above 0.75) and both gender and asymmetry influences could be neglected. Foot roll-over during jogging started with heel contact followed by a latero-medial contact of the metatarsals and finally the hallux. After heel off, the forefoot started to push off at the lateral metatarsals, followed by a more central push off over the second metatarsal and finally over the hallux. Based on the plantar pressure data, the stance phase during running was divided into four distinct phases: initial contact (8.2%), forefoot contact (11.3%), foot flat (25.3%) and forefoot push off (55.1%). These findings provide a reliable and representative reference dataset for temporal characteristics of foot roll-over during jogging of young adults that may also be relevant in the evaluation of running patterns.

Adolescent↗

PubMed2005

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse.

Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.

Animals↗

PubMed2005

Intrinsic risk factors for inversion ankle sprains in females--a prospective study.

Ankle sprains are extremely common. However, very little is known about the variables that predispose individuals to these injuries. The purpose of this study was to examine prospectively intrinsic risk factors for inversion sprains in a young physically active female population. One hundred and fifty-nine female physical education students were evaluated for several possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical and physical characteristics, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control and muscle reaction time during a sudden inversion perturbation. All sports injuries were registered during 1-3 years and exposure to sport was recorded (mean: 15.33+/-4.33 h a week). Thirty-two (20%) of the 159 females sprained their ankle. The number of ankle sprains per 1000 h of sports exposure was 0.75. The Cox regression analysis revealed that females with less accurate passive joint inversion position sense [hazard ratio (HR): 1.08, 95% confidence interval (CI): 1.02-1.14 for absolute error at 15 degrees inversion], a higher extension range of motion at the first metatarsophalangeal joint (HR: 1.03, 95% CI: 1.00-1.06) and less coordination of postural control (HR: 0.96, 95% CI: 0.93-1.00 for endpoint excursion; HR: 0.94, 95% CI: 0.89-0.99 for maximal endpoint excursion) are at greater risk of an ankle sprain. The findings of this study suggest that effective prevention and conservative rehabilitation of ankle inversion sprains should include attention to these variables.

Adolescent↗

PubMed2004

Ultrasound-guided biopsy as a diagnostic aid in three horses with a cranial mediastinal lymphosarcoma.

An ultrasound examination of the thorax of three horses which were performing poorly or had mild signs of colic showed that they had a cranial mediastinal mass and a pleural effusion. A cytological examination of the pleural fluid showed that it did not contain neoplastic cells. A histological examination of an ultrasound-guided core biopsy of the cranial mediastinal mass showed that in each of the three horses it was a lymphosarcoma.

Animals↗

PubMed2004

Locomotion in bonobos (Pan paniscus): differences and similarities between bipedal and quadrupedal terrestrial walking, and a comparison with other locomotor modes.

One of the great ongoing debates in palaeo-anthropology is when, and how, hominids acquired habitual bipedal locomotion. The newly adopted bipedal gait and the ancestral quadrupedal gait are most often considered as very distinct, with each habitual locomotor mode showing corresponding anatomical adaptations. Bonobos (Pan paniscus), along with common chimpanzees (P. troglodytes), are the closest living relatives to humans and their locomotion is valuable for comparison with other primates, and to gain an insight in the acquisition of human bipedalism. Bonobos are habitual quadrupeds, but they also engage in bipedal locomotion, both on terrestrial and in arboreal substrates. In terms of kinematics and dynamics, the contrast between bipedal and quadrupedal walking seems to be more subtle than one might expect. Apart from the trunk being approximately 37 degrees more erect during bipedal locomotion, the leg movements are rather similar. Apart from the heel, plantar pressure distributions show subtle differences between bipedal and quadrupedal locomotion. Regardless, variability is high, and various intermediate forms of locomotion (e.g. tripedal walking) exist both in captivity and in the wild. Moreover, there is overlap between the characteristics of walking and other locomotor modes, as we show with new data of walking on an inclined pole and of vertical squat jumps. We suggest that there is great overlap between the many locomotor modes in bonobos, and that the required polyvalence is reflected in their anatomy. This may hamper the development of one highly specialized gait (i.e. bipedalism), which would constrain performance of the other types of locomotion.

Animals↗

PubMed2003

Percutaneous puncture technique for treating persistent retropharyngeal lymph node infections in seven horses.

Between 1999 and 2001, seven horses with fever, dysphagia and a history of chronic upper respiratory tract infection lasting between three weeks and three months were examined. They had been treated unsuccessfully with a variety of antibiotics for three to four weeks. A deep abscess in a retropharyngeal lymph node was diagnosed in each case by clinical examination, endoscopy and echographic examination of the retropharyngeal region. The infected retropharyngeal lymph node of each horse was punctured with a spinal needle under ultrasound guidance. Pus was aspirated from four of the horses, and their abscesses were then rinsed with 0.9 per cent saline solution, and antibiotics (sodium ceftiofur or penicillin) were injected. In the other three horses the pus was too viscous to be aspirated, and the enlarged lymph node was opened along the tract of the needle and rinsed with chlorhexidine. All the horses were treated with penicillin for two weeks and in six of them the clinical signs gradually disappeared. The other horse continued to show fever and the penicillin treatment was continued for another 10 days, after which the signs gradually disappeared over a period of two months.

Animals↗

PubMed2003

Human water contacts patterns in Schistosoma mansoni epidemic foci in northern Senegal change according to age, sex and place of residence, but are not related to intensity of infection.

In an epidemic focus in northern Senegal, adults had lower intensities of infection than adolescents, a phenomenon that could not be attributed to immunity acquired over the previous 10-15 years of exposure to the parasite because all age groups had had the same number of years' experience of the worm. This article considers whether this pattern could have been because of higher levels of exposure to the parasite in younger age groups. Personal contact with infected water was recorded using a questionnaire in Schistosoma mansoni foci not more than 3 years old and in another, 10-year-old focus. Many aspects of contact (e.g. frequency, duration or time of day of contact) may contribute to the number of encounters with infective cercariae (true exposure), so various assumptions regarding the relationship between water contact and true exposure were tested resulting in a range of exposure indices. People reported a mean of 4.4 separate contacts, and spent a median of 57 min per day in water. Patterns of water contact differed depending on the exposure index used, e.g. considering duration, males spent a longer time in water than females (P < 0.001). But using frequency, females had more contacts with water than males in most villages (P < 0.001). Generally, exposure levels dropped as people become aged (P < 0.001) and residents of the older focus were more exposed than residents of other foci (P < 0.002). Intensity of (re)infection was not related to exposure either alone or in models incorporating age, sex and/or village irrespective of the index used. There is therefore evidence that age, sex and place of residence determine exposure but none to suggest that exposure had an influence on the relationship between these factors and intensity of infection. We propose therefore that in this population other factors have principal importance in determining intensity of infection.

Adolescent↗

PubMed2002

Efficacy of artesunate and praziquantel in Schistosoma haematobium infected schoolchildren.

Praziquantel is the current mainstay for morbidity control of schistosomiasis. Artemisinin and its derivatives, widely used for the treatment of malaria, also display antischistosomal properties. The present study is an effort to assess the therapeutic efficacy of artesunate, an artemisinin derivative, in Schistosoma haematobium infections in a human population. The efficacy of artesunate and praziquantel were comparatively studied in primary schoolchildren from two villages, Lampsar (n=180) and Makhana (n=108), located along the Lampsar river in the delta of the Senegal River Basin in Northern Senegal (West Africa). In each village, half of the infected children were treated with a single oral dose of 40 mg/kg praziquantel and half with artesunate following the recommended malaria monotherapy regimen. For both drugs, cure and egg count reduction rates were, without apparent explanation, higher in Makhana than in Lampsar. In both villages, high and nearly comparable egg count reduction rates were obtained with both drugs at each follow-up after treatment (5, 12 and 24 weeks) in the heavy infected group of children (>50 eggs/10 ml of urine). No major adverse effects were observed. The results demonstrate that artesunate is effective against S. haematobium, but the results obtained with praziquantel were consistently better.

Adolescent↗

PubMed2002

Treadmill exercise negatively affects visual contribution to static postural stability.

This study was undertaken to explore the nature of impaired postural stability following physical exercise. Nine healthy subjects (aged 24 +/- 3 years) were subjected to 30 min of treadmill walking or running on two separate occasions. Walking and running speeds (1.9 to 2.2 m/s) were chosen to induce equal energy expenditure. During treadmill exercise, kinematic analysis of head movement was performed. Prior to and immediately following exercise, postural sway was evaluated as mean velocity of centre of pressure (VCOP), measured on a force plate during 30 s quiet stance with eyes open or eyes closed. The results indicate that exercise increased two-dimensional postural sway by 9 - 19 % in eyes open, but not in the eyes closed condition. The deteriorating effect of exercise was both evident in the sagittal and in the frontal plane, although the effect on the former was slightly more transient. Post-exercise sway values were significantly higher after running than after walking. Kinematic analysis of head movement confirmed larger vertical displacement and acceleration pattern in running compared to walking. It is concluded that exercise of moderate intensity deteriorates visual contribution to postural stability. The effect is evident as an initial destabilisation in the sagittal direction and a less transient loss of latero-lateral stability. Running tends to disturb postural stability more than walking, possibly due to more excessive head movement and disturbance of vestibular and visual information centres.

Adult↗