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E Roy

Publications and source records attributed to E Roy.

At least 37 records · Page 2Linked to original sources
PubMed1998

The narrow band hypothesis: an interesting approach for high-intensity transient signals (HITS) detection.

We propose a new approach to detect microemboli automatically using the narrow band hypothesis. An initial database of 560 peripheral arterial Doppler high-intensity transient signals (HITS) was created to study microemboli and to define the normal limits to be used in our method. When a HITS occurs, our approach consists of modelling the Doppler signal using amplitude and frequency wave modulation. A threshold was defined experimentally using this database and then applied to 38 recordings from 12 patients. Using another database, six expert Doppler users reported 140, 176, 155, 161, 161 and 146 HITS, corresponding to a total of 197 different observed HITS. When an event was detected by 6, 5, 4, 3, 2 and 1 of the observers, the sensitivity of the automatic detection was 94.8%, 75.9%, 55.6%, 42.9%, 30% and 0%, respectively. The sensitivity of our automatic detection thus is highly associated with the likelihood (defined as the ratio of observers in agreement to the total number of observers) of an event: r = 0.99 for p < 0.0001. Although future research would result in improvement of the specificity, the narrow band hypothesis appears to be a promising technique for the detection of HITS.

Blood Flow Velocity↗
PubMed1995

Mesencephalic grafts partially restore normal nigral dynorphin levels in 6-hydroxydopamine-lesioned rats treated chronically with L-dihydroxyphenylalanine.

An increase of dynorphin levels is commonly observed in the substantia nigra of 6-hydroxydopamine-lesioned rats chronically treated with daily injections of L-DOPA. This study investigates the potential of fetal mesencephalic grafts to restore normal levels of dynorphin in such cases. After 19 consecutive days of treatment with L-DOPA, lesioned rats with the most severe nigral cell loss showed increased levels of dynorphin in the substantia nigra ipsilateral to the lesion, as expected. The changes were assessed by standard immunohistochemical techniques combined with the use of an image analysis system. Such changes were not observed in the substantia nigra of rats that received fetal mesencephalic cells in the striatum six months prior to the beginning of the chronic treatment. However, only animals displaying heavy loss of dopaminergic neurons in the substantia nigra pars compacta showed significant changes of dynorphin levels in the substantia nigra following drug treatment. Our results show that fetal nigral cells transplanted into the striatum have the potential to prevent biochemical changes observed in the basal ganglia induced by the lesion of the nigrostriatal pathway and chronic treatment with L-DOPA. It is still hypothesized from studies in rodents that this peptide may play a role in the appearance of DOPA-induced dyskinesia, because dynorphin levels increase in the substantia nigra pars reticulata after L-DOPA treatment. If this happens to be the case, then the use of fetal nigral grafts could therefore be an important step to prevent the induction of dyskinesia after chronic L-DOPA treatment.

Amphetamine↗
PubMed1994

Effectiveness of and compliance to preventive measures against the occupational transmission of human immunodeficiency virus.

To prevent the occupational transmission of human immunodeficiency virus (HIV) and other blood-borne infections in health care settings, guidelines have been issued as universal precautions and body substance isolation. Patient testing has also been advocated. The literature on the compliance to and effectiveness of these measures was reviewed and analyzed to establish the state of knowledge and make appropriate recommendations to improve guidelines. It showed that workers' compliance to recommended measures is relatively poor. The effectiveness and cost-effectiveness of universal precautions and body substance isolation remain to be demonstrated. Testing patients for HIV infection and other bloodborne pathogens does not appear to be a more appropriate solution. Focus should be placed on preventing parenteral exposures and applying risk assessment methods to identify health care settings and procedures at higher risk. These measures would allow safer medical devices to be targeted and would ensure that financial resources would be available to implement appropriate preventive measures.

Guidelines as Topic↗
PubMed1993

Deprenyl increases survival of rat foetal nigral neurones in culture.

To study the potential of L-deprenyl to rescue dopaminergic neurones from natural death in primary cultures, foetal nigral neurones were prepared from the ventral midbrain of 16 day old rat embryos. L-deprenyl, at final concentrations of 0.1, 1 and 10 microM, or vehicle solution was added to the culture medium. The cells were allowed to survive for 1, 5 and 10 days. They were then fixed and stained for tyrosine hydroxylase (TH) immunohistochemistry, with or without histological staining. After 5 and 10 days, deprenyl at 0.1 microM increases the number of TH-positive profiles in treated cultures when compared with controls but the effect was more evident at 1 and 10 microM. This can be interpreted as increased survival of catecholaminergic neurones. We cannot however rule out the possibility that deprenyl stimulates the expression of TH by other neurones.

Animals↗
PubMed1992

[AIDS and adolescence].

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Mesoblastic nephroma presenting as a haemorrhagic cyst.

Two cases of haemorrhagic renal cyst presenting in the neonatal period are described. Ultrasound examination, excretory urogram, and MRI, gave diagnosis in the second case. The remarkable histopathologic pattern of these two cases has led to propose correct diagnosis of pure cystic mesoblastic nephroma, an unusual variety of mesoblastic nephroma.

Diagnostic Imaging↗
PubMed1990

Analysis and perspectives of endoscopic treatment of vesicoureteral reflux in children with a 20-month follow-up.

We report our experience with the endoscopic treatment of vesicoureteral reflux by a submucosal injection of Teflon in children. During a period of 20 months, 291 refluxing ureters were injected by 4 members of our surgical team. A cystography was performed 3 months later. Because 53 children have a follow-up of less than 3 months, we only consider the remaining 201 ureters. The success rate is 92% which is similar to that of surgical treatment. We insist on some precautions and contraindications. Endoscopic treatment is an undeniable progress, but surgical treatment is still required in some cases.

Child, Preschool↗
PubMed1990

[Magnetic resonance imaging of the brain of newborn infants].

The authors report their experience of cerebral magnetic résonance imaging (MRI) in the neonatal period. MRI offers many advantages compared to CT scan or ultrasonography in the study of malformations, tumors, infections and anoxic-ischemic brain injury. However, MRI is limited by the duration of the examination the need for total immobility which is achieved in the neonate via administration of chloral hydrate, and lack of accessibility. MRI is a non invasive method for following in vivo brain development during infancy.

Brain↗
PubMedDate not supplied

The use of reaction time measures to evaluate nonword reading in primary progressive aphasia.

We reported on a subject with nonfluent primary progressive aphasia (PPA), NL, who demonstrated an impaired ability to make rhyme judgments (Dowhaniuk, Dixon, Roy, Black, & Square, in press). Our hypothesis was that these deficits represent a precursor to phonological alexia. However, no definitive evidence supported the existence of a phonological reading impairment as NL made relatively few errors reading nonwords. To further evaluate NL's nonword reading, nonword and real word reaction times were compared. NL's reaction times were significantly longer for only nonwords compared to the slowest control subject. We then assessed the first two stages of processing involved in nonword reading (Coltheart, 1996). NL did not demonstrate deficits with graphemic parsing or phoneme assignment. His continuing problems with auditory rhyme judgments support the presence of a phonological processing deficit not specific to reading. We conclude that reaction time measures allow for the detection of subtle nonword reading deficits.

Aged↗
PubMedDate not supplied

Visual aiming movements in Alzheimer's disease.

This study examined whether AD affects the control of pointing movements. Sixteen older adults with probable AD and 10 age-matched healthy adults pointed at targets varying in size (3 and 7 mm in diameter) and located at three positions (at the midline and 33 degrees to the left and right). Results revealed the patients exhibited longer movement time, lower peak velocity and more time in deceleration, although they exhibited effects of target size and location comparable to the healthy controls. AD, then, would appear to slow down movement without affecting the motor system's ability to respond to task demands.

Aged↗
PubMedDate not supplied

Rett syndrome as a minicolumnopathy.

OBJECTIVE: Rett syndrome is a progressive neurological disorder affecting primarily females. It is characterized by the early regression of acquired language, cognitive functions, social skills, and purposeful hand function. Patients with Rett syndrome are often misdiagnosed as autistic. Recent reports of minicolumnar abnormalities in the brains of autistic and Asperger's syndrome prompted us to search for similar pathology in Rett syndrome. MATERIAL: The patient population consisted of 5 Rett syndrome patients (mean age = 14.4 +/- 4.0 years) and 17 controls (mean age = 14.6 +/- 9.5 years). Tissue was celloidin embedded, sectioned at 35 um and Nissl stained. Images (100x) were taken from Brodmann's areas 9, 21, and 22 from layer III of the left hemisphere. METHOD: Columnar width measurements for these images were obtained with computerized image analysis using previously published algorithms. Each area was analyzed separately with univariate ANOVA, including diagnosis as a fixed factor and age (linear and quadratic terms), and sex as covariates. RESULTS: Diagnosis dependent effects were statistically significant only in area 21 (p = 0.009) even when taking into account a Bonferroni correction for the multiple comparisons. CONCLUSION: Both the regional nature of the changes as well as differences in mean cell spacing differentiates the abnormal minicolumnar morphometry of Rett syndrome from that of autism.

Adolescent↗