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Biomedical subjects

Y Robitaille

Publications and source records attributed to Y Robitaille.

152 records · Page 9Linked to original sources
PubMedDate not supplied

Increased activity of choline acetyltransferase and acetylcholinesterase in actively epileptic human cerebral cortex.

We measured the activities of the cholinergic marker synthetic and catabolic enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in surgical specimens obtained from 38 patients immediately following anterior temporal lobectomy for intractable epilepsy. Samples from patients with actively spiking lateral temporal cortex were compared to non-spiking lateral temporal cortex obtained from patients in whom the epileptic discharges were confined to the hippocampus. Mean activities of ChAT and AChE were increased by 25% (P less than 0.01) and 30% (P less than 0.025) respectively in the spiking vs. non-spiking cortex. We suggest that the above-normal activity of these cholinergic marker enzymes may reflect sprouting of cholinergic nerve terminals in spontaneously spiking cortex of some patients and/or increased acetylcholine metabolism secondary to the stimulatory effect of the ongoing epileptic discharge.

Acetylcholinesterase↗
PubMedDate not supplied

Low-grade myxoid chondrosarcoma of the base of the skull: CT, MR, and histopathology.

A retrospective CT, MR, and histopathologic study was performed in five patients with histologically verified low-grade myxoid chondrosarcoma of the base of the skull. In four patients, the tumor originated off the midline and was associated with bone destruction at the petrous apex near the petrooccipital fissure. Tumor extent included the cerebellopontine angle in three patients and the parasellar area in two patients. The fifth tumor originated on the midline and was associated with destruction at the dorsum sellae. Three tumors contained calcifications, whereas two lesions were mostly isodense with brain on CT scan. All tumors were hypointense on T1-weighted MR images and very intense on T2-weighted images except for areas of signal void consistent with calcifications. Light microscopy revealed islands of mature hyaline cartilage in an abundant myxoid ground substance. Histology and immunocytochemical analysis were consistent with a low-grade myxoid chondrosarcoma. The CT and MR features of low-grade myxoid chondrosarcoma are comparable with those of chordoma. Chordoma usually arises from the midline, but cases with origin from the lateral portion of the clivus or the petrous apex have been described. Low-grade myxoid chondrosarcoma has distinct histologic and immunocytochemical features and includes lesions formerly called "chondroid chordomas."

Adolescent↗
PubMedDate not supplied

Familial Alzheimer's disease and cortical Lewy bodies: is there a genetic susceptibility factor?

The reason for the occurrence of Lewy body disease (LBD) in Alzheimer's disease (AD) patients is unknown. If brains from etiologically different AD groups differ in their tendency to develop cortical Lewy bodies, the concurrence of LBD in AD patients may be a manifestation of the AD process in specific AD subsets. To address this issue, we counted cortical Lewy bodies in AD patients with genetic abnormalities on chromosome 14 (n = 19), and chromosome 21 (n = 3), sporadic AD (n = 27), Down's syndrome (n = 1) and control (n = 26) patients. Cortical Lewy bodies were occasionally present in AD patients with long-duration disease in most of the above AD subgroups, but were not present in any of our age-matched control cases. We suggest that cortical Lewy body formation may be an intrinsic part of the late pathologic changes of AD regardless of etiology and that it is not specific to any of the AD subtypes studied.

Aged↗
PubMedDate not supplied

New patterns of intraneuronal accumulation of the microtubular binding domain of tau in granulovacuolar degeneration.

Sixteen brains from Alzheimer's disease (AD) patients with varying duration of dementia were studied using the monoclonal antibody (mAb) 6.423 raised against the three repeated domains of the tau protein, and named the paired helical filament (PHF) core. In Ammon's horns of the AD cases 6.423 mAb, in addition to immunoreacting with neurofibrillary tangles (NFTs), dystrophic neurites, and plaquelike structures, also recognized a subpopulation of granulovacuolar degeneration elements (GVD). A new immunoreactive structure, a spherical inclusion, was also stained by 6.423. The immunoreactive GVD elements and the spherical inclusion were found in the aged controls (greater than 65 years of age) and in non-AD dementia cases, as well. The staining of the GVD was markedly decreased when the tissue was preincubated with alkaline phosphatase. In contrast, NFTs and the spherical inclusions resisted dephosphorylation. Neurons containing the spherical inclusion frequently lacked immunoreactive intracellular NFTs. Due to the similar immunohistochemical properties between the spherical bodies and immunoreactive NFTs, we named this new inclusion PHF core body. Our results suggest that the PHF core body may represent a successful attempt by hippocampal neurons to restrict the PHF core expression. Thus, the failure of this mechanism may lead to the NFT formation in a range of dementing processes. Alternatively, the PHF core body may be an early stage in the NFT formation.

Adult↗
PubMedDate not supplied

[Preliminary results on the residence distribution at birth of patients with Alzheimer's disease in the Saguenay-Lac-Saint-Jean/Quebec (the IMAGE project)].

The IMAGE Project is pursuing the establishment of a population-based registry of Alzheimer's disease (AD) cases in the Saguenay-Lac-Saint-Jean (SLSJ) (Quebec). The authors report on the spatial distribution at birth of 221 possible, probable and definite cases. A large network of key-informants for screening AD cases has been established over SLSJ. The spatial distribution of cases at birth and at the onset of disease has been computed by calculating the Alzheimer birth rate (ABR) on the basis of three scales: six specific geographical spheres of screening, all municipalities, and the public health departments. The statistical significance of results was determined using the theoretical Poisson and the Chi square distributions. ABR for each of the geographical spheres of screening showed no statistically significant differences considering either residence at the onset of the disease or residence at birth. Furthermore, differences were observed between rural and urban areas with an interesting trend for a higher number of cases than expected in one area of SLSJ. The spatial distribution of cases considered on the basis of residence at birth appears to show a different pattern, but no significant, from that measured on the basis of residence at the onset of disease. Screening of cases is actively being pursued all across SLSJ by the IMAGE network. There is a clear trend towards rural residence at birth of cases. It remains to see whether or not this observation is due to a geographical concentration of familial cases.

Alzheimer Disease↗
PubMedDate not supplied

Does play equipment conform to the Canadian standard?

In the summer of 1991, play equipment in 254 playgrounds located on the island of Montreal were inspected, using a checklist made up of items drawn from the Canadian standard for the safety of children's playspaces and equipment. The results of the study, covering 605 climbers, 522 swings and 181 slides, made it possible to identify the most and least respected aspect of safety. For example, one out of two pieces of play equipment was installed on a protective surface that did not conform to the Canadian standard; seven out of ten swings had seats made of non-impact-absorbing materials; and six out of ten pieces of equipment had head entrapment openings. Knowing the physical shortcomings of play equipment is an important step in reducing injuries sustained on it. However, to be effective, the prevention of injuries related to play equipment requires a concerted effort on the part of several partners.

Child↗