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Biomedical subjects

E Vandenbussche

Publications and source records attributed to E Vandenbussche.

At least 37 records · Page 2Linked to original sources
PubMed2001

Bilateral cataract and high myopia in a child with trichothiodystrophy: a case report.

Trichothiodystrophy refers to a group of autosomal recessive disorders that have in common brittle sulphur-deficient hair (7). The abnormalities are usually obvious at birth and the clinical expression is variable. Ocular abnormalities are common with bilateral cataract being the most frequent one. We report on a four year old boy with trichothiodystrophy (complementation group TTD-A) who presented to us with strabismus, high myopia and bilateral cataract.

Abnormalities, Multiple↗
PubMed2000

Sampling extracellular aspartate, glutamate and gamma-aminobutyric acid in striate cortex of awake cat by in vivo microdialysis: surgical and methodological aspects.

A method which permits repeated microdialysis in the cortical layers of area 17 of the awake cat is described. Under visual control through a surgical microscope and using a stereotactic instrument, four probe guides are permanently implanted in area 17 of one hemisphere of the anesthetized animal and two fixation bars are mounted on the skull to allow fixation of the cat in a stereotactic frame. The implantation of four probe guides in the same hemisphere allows simultaneous sampling from different cortical regions serving different parts of the visual field. A removable transparent cover protects the probe guides. After recovery from surgery the awake cats are trained to adapt to a fixation of 5 h in a stereotaxic apparatus. Once adapted to that situation, the cats are ready for microdialysis experiments without anesthesia. The day of the experiment, the awake animal was fixed in the stereotactic frame and the probes inserted into the guides. To test the validity of the method, the basal efflux and the depolarization efflux, triggered by the addition of 65 mM K(+) to the artificial cerebrospinal fluid, of the amino acids aspartate, glutamate and gamma-aminobutyric acid are measured by two HPLC-electrochemical detection methods. The exact localization of the probes and the reaction of the surrounding tissue is studied using immunocytochemistry for glutamate and glial fibrilary acidic protein. Our neurochemical and morphological results suggest the feasibility of multiple and repeated probe insertions for microdialysis experiments in the cerebral cortex of awake and behaving cat. This method provides a new tool to investigate the cortical plasticity.

Animals↗
PubMed2000

Impairment in motion discrimination tasks is unrelated to amount of damage to superior temporal sulcus motion areas.

The behavioral role of the middle temporal (MT/V5) area and its satellites in motion processing is still unclear, particularly the degree to which MT/V5 proper is critical for different types of motion processing. Therefore, effects of small and large lesions in the caudal part of the superior temporal sulcus of macaque monkeys were compared for two tasks requiring different types of motion processing: a direction and a kinetic orientation discrimination. The small lesion was restricted to the peripheral representation of MT/V5 but included V4t, whereas the large lesion included all of MT/V5 and the medial superior temporal (MST) area as well as substantial parts of the floor of the superior temporal (FST) area. Both lesions resulted in significant and long-lasting impairment of direction discrimination but had a lesser effect on kinetic orientation discrimination. Thus the effects of small STS lesions on motion perception are much stronger than expected.

Animals↗
PubMed2000

Relation between visual perceptual impairment and neonatal ultrasound diagnosis of haemorrhagic-ischaemic brain lesions in 5-year-old children.

Visual-perceptual abilities were assessed in 5-year-old children with the following neonatal neurological conditions: born preterm with normal ultrasound scan (NL, n=17); born preterm with ultrasound diagnosis of intraventricular haemorrhage (IVH, n=17); born preterm with ultrasound diagnosis of periventricular leukomalacia (PVL, n=12); born term with hypoxic-ischaemic encephalopathy (HIE, n=11). Visual-perceptual ability was evaluated with the L94: eight visual-perceptual tasks designed to evaluate different aspects of visual perception at the preschool level in children with multiple disabilities. Impairment was established in comparison to the performance age obtained on non-verbal intelligence subtests, instead of chronological age. Frequency of L94 impairment was highest in children with PVL, while children with IVH did not differ from the NL control group. Impairment rates were increased also in children with transient periventricular echodensities, and in children with HIE. Impairments were only moderately related to the delay of visual acuity maturation in infancy.

Cerebral Hemorrhage↗
PubMed2000

A new cat Fos antibody to localize the immediate early gene c-fos in mammalian visual cortex after sensory stimulation.

We developed a novel antibody against cat Fos by immunizing rabbits with a 26-amino-acid peptide. Immunocytochemistry on visual cortex of cats undergoing different visual manipulations was applied to test the reliability and the efficacy of this antiserum. One hour of light stimulation after an overnight dark adaptation resulted in strongly induced Fos expression in supra- and infragranular layers of cat primary visual cortex. Short-term monocular deprivation changed the Fos expression profile into a columnar immunostaining related to ocular dominance columns. Fos expression has also been analyzed in cats in which visual input was confined to the right hemisphere by sectioning the left optic tract and the corpus callosum. In the right hemisphere, visual stimulation elicited Fos induction, whereas in the contralateral hemisphere a very low Fos signal was observed. The specificity of this newly synthesized antibody was confirmed by Western blotting. To further establish the applicability of this Fos antiserum, we performed immunostaining on monkey and rat visual cortex. This new cat Fos antibody appears to be excellent for study of Fos expression as a marker for mapping neuronal activity in mammalian brain.

Animals↗
PubMed2000

Visuoperceptual impairment in multiple sclerosis patients diagnosed with neuropsychological tasks.

A comprehensive set of 31 binocular neuropsychological tasks assessing a series of spatial and non-spatial visuoperceptual abilities was used to study visuoperceptual impairment in a representative group of 49 MS-clinic patients exhibiting neither diagnosed ophthalmological afflictions nor major psychiatric diagnoses. Among these patients, true frequency rate of visuoperceptual impairment, i.e. of subjects failing four or more tasks, was estimated at 26%. The pattern of visuoperceptual impairment was non-uniform, non-selective, restricted and idiosyncratic. Only four tasks yielded significant rates of impairment. They concerned colour discrimination, the perception of the Müller-Lyer illusion and object recognition in two separate conditions. Each of the four factors identified by factor analysis had an important representative (with factor loading >0.35) among these four tasks. Failures on these tasks correlated poorly. Together, the four tasks satisfactorily predicted visuoperceptual impairment as defined by the comprehensive set of tasks (sensitivity 86.7%; specificity 81.3%), but with regard to an uncontaminated criterion, their aggregate sensitivity and specificity was only 75 and 56% respectively. Visuoperceptual neuropsychological task performance related significantly but weakly to cognitive status, physical disability and to pyramidal, cerebellar and brain stem neurological signs, and did not correlate with other clinical neurological signs, disease duration, type of MS, a history of optic neuritis, depression or medication status Multiple Sclerosis (2000) 6 241 - 254

Adult↗
PubMed1999

Temporal resolution deficits in the visual fields of MS patients.

We assessed the relationship between temporal resolution and MS-induced neuropathy. A diagnostic strategy comprising assessments of temporal resolution at 16 points in the extra-foveal visual field up to 12 degrees from the fovea was first compared with foveal temporal resolution and with a standard VEP procedure in the same MS patients. At the group level, foveal temporal resolution was less sensitive to demyelination than the 16-point diagnostic strategy, the detection rate of which was comparable to that of the VEP procedure. Cross-sensitivity of the VEP and the 16-point diagnostic procedure was low. Subsequently, the average severity of MS-induced temporal resolution deficits was studied at three retinal loci of the same size but different eccentricities. Foveal deficits were not significantly greater than more peripheral deficits within the central 12 degrees.

Adult↗
PubMed1999

Separating visual perception and non-verbal intelligence in children with early brain injury.

The relationship between impairments of visual perception and of non-verbal intelligence was studied in 28 children who, due to the nature of their neurological pathology, were at risk for visual perceptual impairments (high-risk), and 18 mentally disabled children without such risk (low-risk). Their age range was 3-14 years. A child was considered specifically visual-perceptually impaired (VPI) if performance on the De Vos task, a visual object recognition task, was weaker than expected from the baseline performance level obtained on non-verbal intelligence subtests. Accordingly, 22 high-risk children (79%) were classified VPI, against only four low-risk children (22%). Comparing intelligence data of children with and without VPI revealed a WPPSI non-verbal to verbal intelligence impairment in the former. At the subtest level, comparing five verbal and five non-verbal WPPSI subtests, and five subtests from the Snijders-Oomen non-verbal intelligence scale, revealed a difference only on Animal House. The absence of any systematic effects of specific visual perceptual impairment on intelligence subtest performance leads us to conclude that in these children VPI and selective non-verbal intelligence impairment coexist as two separate and irreducible deficits.

Brain Injuries↗
PubMed1999

[Cadaver study of acetabular cup mobility in the healthy hip and prosthesis by monopodal pressure simulation ].

PURPOSE OF THIS STUDY: The purpose of this study was to quantify relative displacement of anterior and posterior horn of the acetabulum lunate surface using Omega strain gauges while increasing loads were applied to the hip joint. Measurement were performed on fresh cadaver bones in unipodal stance using experimental method before and after socket's implantation. MATERIAL AND METHODS: [corrected] Nine skeletons, from fresh non-embalmed cadavers, including pelvis, the three last lumbar vertebrae and both femurs were maintained in unipodal equilibrium using metallic cables for muscle passive simulation. Loads were applied up to 700 N. Specific extensometric Omega strain gauges were created and tested, with 5 mu of sensibility. Measurement of displacement between horns were studied on two sides of each pelvic before and after implantation of conventional and prototype cemented or press fit implants. RESULTS: Among 81 loads on 18 acetabulum healthy and implanted, displacement was significant in 58 cases with a spacing of horn of 7 to 140 mu with average 31.1 mu and non significant in 25 cases. On healthy acetabulum, spacing was variable from 12 to 140 mu (average 43.2 mu) in 18 of 26 loads. On implanted acetabulum by different sockets, spacing was variable from 7 to 100 mu (average 27.4 mu) in 40 of 55 loads. Displacement was function of rotation hip, smaller in internal rotation and larger in external rotation. Spacing of horns was reduced in oversize sockets. DISCUSSION: The data obtains by omega strain gauge suggest acetabular displacement is not univocal under load. There were a widening of the acetabular notch on load. This can be explained by the modification of primary incongruity of the two components of the hip joint because of acetabular deformation. Such results are in agreement with recently published data obtained about length of the transverse acetabular ligament.

Acetabulum↗
PubMed1998

Simultaneous determination of total and extracellular concentrations of the amino acid neurotransmitters in cat visual cortex by microbore liquid chromatography and electrochemical detection.

To investigate the influence of a partial sensory deprivation on the total and extracellular concentration of the amino acid neurotransmitters in cat visual cortex, two microbore HPLC methods were developed for the simultaneous determination of aspartate, glutamate, glycine, taurine and gamma-aminobutyric acid in cat brain extracts or microdialysis samples. For the determination of the total neurotransmitter concentrations in the visual cortex, the brains were quickly frozen and 200-microns cryostat sections were made. From these sections tissue samples of 2 x 2 mm2 containing the six cortical layers were dissected out of the central and peripheral parts of area 17. After homogenisation and centrifugation, the supernatants were used for quantitative amino acid analysis using an o-phthalaldehyde-tert.-butylthiol pre-column derivatisation HPLC gradient elution method on a microbore column (100 x 1 mm I.D.; C8) and single electrochemical detection. Microdialysis samples from area 17 were obtained every 15 min using 2-mm probes perfused with synthetic cerebrospinal fluid at a flow-rate of 1 microliter/min. After o-phthalaldehyde-tert.-butylthiol derivatisation they were analysed on a microbore column by isocratic elution and dual electrochemical detection. The instrumentation and the different separation parameters were optimised and standard curve, recovery, analytical precision and detection limits for each neurotransmitter were determined.

Animals↗
PubMed1998

Temporal and spatial resolution in foveal vision of multiple sclerosis patients.

Deficits of spatial and temporal resolution were compared in a group of 49 definite multiple sclerosis(MS) patients showing no major evidence of previous optic neuritis attack but representative of the population of the Belgian National MS Centre as to age and the most important disease variables. Resolution in the two domains was measured foveally with forced-choice staircase psychophysical procedures using Landoldt C and double flash stimuli, respectively. The two measurements were equally sensitive to MS-induced deficits and did not exhibit cross-sensitivity. Since discrete deficits of either kind were equally prevalent and outnumbered combined deficits, this suggests a nonselective but nonuniform destruction of M and P visual pathway function in these patients.

Adult↗
PubMed1998

Impaired visual perceptual performance on an object recognition task in children with cerebral visual impairment.

Visual perceptual ability and grating acuity were studied in 22 children with cerebral visual impairment (CVI). In most studies indicating visual perceptual impairments in CVI children, the evidence is weakened by the co-presence of reduced nonverbal, relative to verbal, intelligence, which in itself might account for the impaired performance on visual perceptual tasks. Our aim was to show that CVI children's performance on a visual perceptual task is weaker than can be expected from their nonverbal intelligence scores, thus demonstrating an impairment that is specific to visual perception. To this end, we used an object recognition task consisting of 60 line drawings depicting common objects in various aberrant ways. For each drawing, the age was established at which 9 out of 10 normal children could recognise the object depicted. This information was used to select the subset of drawings appropriate for each of the CVI subjects' nonverbal intelligence level, expressed as an age equivalent. Recognition performance on this subset of drawings was impaired in 16 children (72.7%), but was unrelated to visual acuity. We conclude that these children have a specific visual perceptual impairment, which is not reducible to any nonverbal intelligence impairments they might suffer.

Adolescent↗
PubMed1997

A metabolic mapping study of orientation discrimination and detection tasks in the cat.

Increasing evidence suggests that a large number of distinct cortical areas and associated subcortical structures participate in the processing of visual information and that different aspects of visual scenes are evaluated in different areas. This necessitates identification of cortical and subcortical regions cooperating in particular visual tasks. Using the 2-deoxyglucose technique, we monitored the differential activation of areas in the cat visual cortex participating in an orientation discrimination and a detection task. Concordant with previous lesion studies, we found increased activity levels in area 17 in the discrimination condition relative to the detection condition. In addition, the 2-deoxyglucose technique revealed discrimination-related increased activations in the claustrum, the putamen and in parts of the anteromedial, anterolateral and posterolateral lateral suprasylvian visual areas. Regions activated differentially with the detection task comprised subdivisions of areas 17, 18, 19 and 21, posterior area 7 (7p), several areas of the posterior part of the middle and posterior suprasylvian sulcus, the pulvinar complex and the superior colliculus. These results show that the 2-deoxyglucose technique is useful to investigate cognitive brain functions, and that different sets of cortical and subcortical regions are activated during two visual tasks with similar visual stimulation.

Animals↗
PubMed1997

[Acetabulum deformations after implantation of a cemented cup with or without metal-back component. An in vitro comparative study of monopodal load].

PURPOSE OF THE STUDY: The purpose of this study was to find a biomechanical explanation for a clinical failure of metal backed acetabular components. Periacetabular deformations were measured on fresh cadaver bones equipped with strain-gauge rosettes. MATERIAL AND METHODS: Two skeletons, including pelvic bone, the two last lumbar vertebrae, and both femurs were maintained in unipodal equilibrium using metallic cables for muscle simulation. Loads were applied up to 700 N the approximating average body weight. A comparative study of periacetabular deformations was performed: right sides of each pelvic bone were implanted with conventional cemented implants, and left sides with metal backed cemented implants of same diameter and size. RESULTS: Significant differences were noted: whereas no modification was brought by implantation of conventional cemented sockets, periacetabular deformations were reduced and smoothed after implantation of cemented metal backed implants. Such results are in agreement with recently published data obtained, using the finite element analysis method. DISCUSSION: A study of pelvic ring and acetabular walls displacement was performed, but the authors couldn't find any clinical relevance to this biomechanical study.

Acetabulum↗
PubMed1997

[Bad clinical results of cemented caps with metal-backed acetabular components. 124 cases with 21 months follow-up].

PURPOSE OF THE STUDY: The authors reviewed with short term follow-up 124 total hip arthroplasties using a cemented metal-backed acetabular component. The purpose of the study was to evaluate clinical and radiological results because of early periacetabular radiolucent lines reported by Ritter. MATERIAL AND METHODS: Surgical procedures were performed in 1988 and 1989 with Saint-Antoine prosthesis (PSA) including cemented titanium metal-backed socket. Functional results were appreciated with Postel-Merle d'Aubigne's score. Radiological results were appreciated using De Lee and Charnley's criterias for radiolucent lines and Yoder's criterias for socket's migrations. We studied correlation between radiolucent line and age, weight, hip disease, associated bone graft, socket size and technical errors. RESULTS: With short term follow-up (21 months), we found 60.4 per cent hips with a maximal PMA score (18) with an average score of 17.5 per cent. We observed 26.4 per cent of complete periacetabular radiolucent lines with 3 sockets loosening with migration. No significant correlation were found between radiolucent lines and age, weight, hip disease, associated bone graft, socket size, and technical errors. DISCUSSION: This periacetabular radiolucent line rate was comparable to the results of the series using such a cemented metal-backed socket. This rate was clearly higher than the results of others series using cemented polyethylene sockets. These bad results were not correlated to those of finite elements analysis. We think that this is due to metal-backed socket excessive rigidity. CONCLUSION: Because of this high periacetabular radiolucent line rate, despite of finite elements analysis results, we no more use cemented metal-backed acetabular socket since 1991.

Adult↗
PubMed1996

Reversible visual hemineglect.

We have identified a limited region in the posterior, but not anterior, half of the cat's middle suprasylvian region which, when cooled and inactivated unilaterally, results in a profound visual neglect of stimuli introduced into the contracooled hemifield. The severity of the deficit matches that induced by unilateral cooling of the superior colliculus. The cortical region is located at the temporo-occipito-parietal junction and is believed to be equivalent to a region centered on or close to the area V5 complex of primates.

Animals↗