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Biomedical subjects

D Nicolle

Publications and source records attributed to D Nicolle.

11 recordsLinked to original sources
PubMed2001

Synaptic sprouting increases the uptake capacities of motoneurons in amyotrophic lateral sclerosis mice.

Using adenoviruses encoding reporter genes as retrograde tracers, we assessed the capacity of motoneurons to take up and retrogradely transport adenoviral particles injected into the muscles of transgenic mice expressing the G93A human superoxide dismutase mutation, a model of amyotrophic lateral sclerosis. Surprisingly, transgene expression in the motoneurons was significantly higher in symptomatic mice than in control or presymptomatic mice. Using botulinum toxin to induce nerve sprouting at neuromuscular junctions, we showed that the unexpectedly high level of motoneurons retrograde transduction results, at least in part, from newly acquired uptake properties of the sprouts. These findings demonstrate the remarkable uptake properties of amyotrophic lateral sclerosis motoneurons in response to denervation and the rationale of using intramuscular injections of adenoviruses to overexpress therapeutic proteins in motor neuron diseases.

Adenoviridae↗
PubMed2001

Functional MRI as a tool to assess vision in dogs: the optimal anesthetic.

Functional magnetic resonance imaging (fMRI) is a recent advance in neuroimaging that provides a picture of brain activity with excellent spatial resolution. Current methods used to evaluate canine vision are poorly standardized and vulnerable to bias. Functional MRI may represent a valuable method of testing vision in dogs if the impacts of anesthesia on fMRI are understood. Six dogs were scanned during visual stimulation, each under three different anesthetic protocols (isoflurane, propofol, fentanyl/midazolam) to address the questions: (1) Can visually evoked fMR signals be reliably recorded in anesthetized dogs? and (2) Which anesthetic agent permits the least suppression of visually induced fMR signal in dogs? This study confirms that visual stimuli reliably elicit neural activity and fMR signal change in anesthetized dogs. No significant differences in images acquired under the three anesthetics were found, and there was no significant relationship between anesthetic dose and brain activity, within the range of doses used in this study. Images obtained during isoflurane anesthesia were more consistent between dogs than those obtained with the other two agents. This reduced variation may reflect the fact that inhalant anesthesia is more easily controlled than intravenous anesthesia under conditions associated with high field fMRI.

Anesthesia↗
PubMed1998

Using a synoptophore to test Listing's law during vergence in normal subjects and strabismic patients.

The synoptophore was used to measure torsional interocular disparity. This, in turn, was used to compute how much the angle between the Listing's plane (LP) of the two eyes changes as a function of the vergence angle. The ratio of these two angles was defined as G. We measured G in normals and in patients suffering from intermittent horizontal strabismus. Consistent with previous search-coil experiments and with our previous visual test measures, the results using the synoptophore suggest that, for normals, G is less than 1. In the patient group the mean G was similar in magnitude but more variable. The variations in G did not appear to be related to the patient's measurement of ocular deviation. This result suggests that the vergence-related rotation of LP in these patients may be related to other factors besides the effort required to fuse the lines of sight.

Convergence, Ocular↗
PubMed1995

Adapting to monocular vision: grasping with one eye.

The aim of the present study was to determine whether normal subjects with one eye covered and patients in whom one eye had been enucleated generate more head movements than subjects using binocular vision during the performance of a visually guided grasping movement. In experiment 1, 14 right-handed normal subjects were tested binocularly and monocularly in a task in which they were required to reach out and grasp oblong blocks of different sizes at different distances. Although the typical binocular advantage in reaching and grasping was observed, the overall head movement scores did not differ between these testing conditions. In experiment 2, seven right-handed enucleated patients were compared to seven age and sex-matched control subjects (tested under binocular and monocular viewing conditions), on the same task as used in experiment 1. While no differences were found in the kinematics of reaches produced by the enucleated patients and the control subjects, the patients did produce larger and faster resultant head movements, composed mainly of lateral and vertical movements. This suggests that enucleated patients may be generating more head movements in order to better utilize retinal motion cues to aid in manual prehension.

Adaptation, Physiological↗
PubMed1995

Rotation of Listing's plane by horizontal, vertical and oblique prism-induced vergence.

We examined the changes in Listing's plane resulting from prismatically induced vergence. The three-dimensional angular positions of the two eyes were compared in normal subjects wearing search coils and gazing at targets 1.9 m away with and without prisms. For horizontal base-out prisms each degree of convergence in one eye yielded 0.72 deg of temporal rotation of Listing's plane in that eye. The results from vertical prisms were not what was expected from the horizontal results. A base-up prism on the right eye induced a downward and temporal rotation of Listing's plane. A base-down prism on the right eye induced an upward and nasal rotation of Listing's plane. The effects of oblique prisms were those expected from combining the effects of horizontal and vertical prisms. Thus in addition to producing a horizontal or vertical misalignment of the gaze line, prisms induce an unexpected position-dependent torsional disparity.

Convergence, Ocular↗
PubMed1995

The development of adaptive head movements following enucleation.

Recent work in our laboratory has revealed that enucleated patients produce large lateral and vertical head movements during visually guided grasping. These movements may allow them to maximise the use of retinal motion cues in planning and controlling their grasp. The aim of the present study was to determine whether the tendency to produce these adaptive head movements increases as a function of time since enucleation. We tested a group of 12 enucleated patients in whom the time between surgery and testing varied from 2 weeks to 35 years (mean = 11.2 years). These patients were required to reach out and grasp oblong blocks of different sizes at different distances. Correlational tests revealed an increase in the proportion of self-generated lateral and vertical head movements versus forward head movements as a function of post-enucleation time (r(s)(12) = 0.68, p < 0.025 and r(s)(12) = 0.65, p < 0.025, respectively). This suggests that enucleated patients may be adapting to living with one eye by learning to increase the proportion of their lateral and vertical head movements during the performance of skilled motor acts.

Adaptation, Physiological↗
PubMed1993

The role of colour flow Doppler ultrasonography in the investigation of disease in the eye and orbit.

Colour flow Doppler ultrasonography is a relatively new technique in which colour-encoded representations of flowing blood are imposed over a conventional grey-scale ultrasound image. This allows interrogation of a relatively large volume of tissue to determine the presence and direction of blood flow. The waveform tracings are then evaluated by means of conventional Doppler imaging. We demonstrate examples of normal vascular structures in the orbit and describe the application of this technique in the investigation of vascular disease, such as carotid-cavernous fistula and ischemic disease. The technique can also be used to evaluate ocular membranes and masses. Colour flow Doppler imaging promises to be an important advance in ophthalmic ultrasonography.

Blood Flow Velocity↗
PubMed1989

Polychlorinated biphenyls.

Polychlorinated biphenyls (PCBs) and their contaminants have definite ocular and dermatologic side effects, often directly related to the serum level of these compounds. These are usually the first symptoms and signs to appear. Other side effects are far more variable, and the carcinogenic role of PCBs and their contaminants remains controversial.

Animals↗
PubMed1980

Eccrine sweat gland carcinoma of the eyelid with orbital involvement.

A 70-year-old man had a sweat gland carcinoma in his right upper eyelid that was slowly growing, but it clinically remained confined to the lid tissues for a period of 25 years. The tumor ultimately extended deeper into the orbit and invaded the sclera, the optic nerve sheath, and the ethmoidal sinuses. Histopathologic examination disclosed malignant features with a variety of cellular patterns. The results of electron microscopic studies confirmed the origin of the tumor from the eccrine sweat glands.

Aged↗
PubMed1980

Mucosal cyst of lacrimal gland fossa simulating lacrimal gland neoplasm.

A 28-year-old man presented with an orbital tumour that was localized by computérized tomography to the fossa of the right lacrimal gland. A benign mixed tumour of the lacrimal gland was the clinical diagnosis, but lateral orbitotomy revealed a subperiosteal cystic mass in the lacrimal gland fossa that extended superiorly and medially into the frontal sinus. Light microscopic examination showed a cyst lined by nonkeratinized stratified squamous epithelium with occasional goblet cells; blood products were present in the lumen, and a chronic inflammatory cell infiltrate was noted in the subepithelial tissue. The possible origins of this mucosal tissue are discussed.

Adult↗