PubMed Health⌕ Search

Biomedical subjects

Frédéric Dubas

Publications and source records attributed to Frédéric Dubas.

9 recordsLinked to original sources
PubMed2006

Myotilinopathy in a family with late onset myopathy.

Mutations in titin are well known cause of late onset autosomal dominant distal myopathy. Mutations in another sarcomeric protein, myotilin, were first identified in two families with dominant limb girdle muscular phenotype. Recently, however, myotilin mutations have been associated with more distal phenotypes in patients with late onset myofibrillar myopathy. We report here a multigenerational French family in which gene sequencing identified a S60F myotilin mutation in all patients with full penetrance despite very late onset. The family was originally reported as a distal myopathy but intrafamilial variability was remarkable with proximal or distal muscle weakness or both. Extended morphological characteristics of muscle biopsy findings in myotilinopathy indicate that immunohistochemistry may be important for selection of molecular genetic approach in myofibrillar myopathy.

Age of Onset↗
PubMed2005

APP locus duplication causes autosomal dominant early-onset Alzheimer disease with cerebral amyloid angiopathy.

We report duplication of the APP locus on chromosome 21 in five families with autosomal dominant early-onset Alzheimer disease (ADEOAD) and cerebral amyloid angiopathy (CAA). Among these families, the duplicated segments had a minimal size ranging from 0.58 to 6.37 Mb. Brains from individuals with APP duplication showed abundant parenchymal and vascular deposits of amyloid-beta peptides. Duplication of the APP locus, resulting in accumulation of amyloid-beta peptides, causes ADEOAD with CAA.

Age of Onset↗
PubMed2005

Arithmetic word-problem-solving in Huntington's disease.

The purpose of this study was to examine executive functioning in patients with Huntington's disease using an arithmetic word-problem-solving task including eight solvable problems of increasing complexity and four aberrant problems. Ten patients with Huntington's disease and 12 normal control subjects matched by age and education were tested. Patients with Huntington's disease performed the solvable problems significantly worse than the normal control subjects, but there was no difference in performance between the two groups in inhibiting aberrant problems. These results suggest that early Huntington's disease patients exhibit a precocious impairment in their ability to plan the resolution of complex arithmetic word problems without deficit in their ability to eliminate aberrant problems. This dissociation of performance fits with what we have found in such patients using script-sequencing tasks (Allain et al., 2004) and with neuropsychological data obtained by Watkins et al. (2000). These results are consistent with what is known about the neuropathological progression of Huntington's disease in which neuronal loss progresses in a dorso-to-ventral direction and with what was shown in patients with circumscribed frontal lobe damage. In these patients, impairments in planning solvable word problems were more frequent when lesions were in the lateral prefrontal regions.

Adult↗
PubMed2005

Executive functioning in normal aging: a study of action planning using the Zoo Map Test.

A particularly important aspect of executive functioning involves the ability to form and carry out complex plans, that is to say planning. This study aimed to investigate planning in 18 older and 16 younger normal participants using an ecological planning subtask derived from the Behavioural Assessment of the Dysexecutive Syndrome test battery, the "Zoo Map Test." There are two trials. The first trial consists of a "high demand" version of the subtask in which the participants must plan in advance the order in which they will visit designated locations in a zoo (formulation level). In the second, or "low demand" version, the participant is simply required to follow a concrete externally imposed strategy to reach the locations to visit (execution level). The two-way ANOVAs mainly showed more difficulties in elderly adults than in younger adults, more difficulties in formulation level than in execution level, and lastly a greater difference between formulation and execution in older participants than in younger adults. These results suggest that elderly participants have some problems developing logical strategies whereas they are able to execute complex predetermined plans.

Adult↗
PubMed2005

Monitoring processes and metamemory experience in patients with dysexecutive syndrome.

The aim of the present study was to determine whether monitoring measures are differentially disturbed in dysexecutive patients after frontal lesions. Twelve dysexecutive patients and 12 healthy controls were administered a paired-associates learning task. Their performances on recall prediction, judgment-of-learning (JOL), and feeling-of-knowing judgment (FOK) were then compared. The results revealed that the two groups differed only on accuracy measures of the FOK paradigm. The study of the overall correlations between the three measures of metamemory revealed a significant relation between recall prediction and accuracy measures of the JOL. We failed to find any significant correlation with the accuracy measures of the FOK. Taken together, our data confirm that metamemory experience is not a unitary construct but rather a group of distinct and quite independent mechanisms.

Adult↗
PubMed2005

[Cerebral microangiopathies].

Cerebral small vessels disease are characterized by lesions of the wall of the small cerebral arteries. They are responsible for 25 to 30% of strokes due to cerebral infarction or hemorrhage and/or cognitive impairment, dementia. Lipohyalinosis and cerebral amyloid angiopathy are the most common etiologies. They are associated with age, arterial hypertension, and diabetes. The localization of the lesions by MRI could help to differentiate both etiologies: deep localisation for lipohyalinosis and lobar (cortical) for cerebral amyloid angiopathy. Physiopathology of these diseases is not presently understood, and no specific treatment is available. Therefore, treatment of vascular risk factors (diabetes, arterial hypertension) is the only therapeutic measure available.

Brain↗
PubMed2003

Selective decrease in axonal nerve growth factor and insulin-like growth factor I immunoreactivity in axonopathies of unknown etiology.

In an attempt to approach the mechanisms underlying axonopathies of unknown etiology, we have studied by immunocytochemistry the fate of several growth factors in eight of such cases that we had previously analyzed by morphometry and which were characterized by a decrease in neurofilaments and an increase in beta tubulin immunostaining. Here we establish that, contrary to beta tubulin, growth-associated protein43 (GAP-43) immunolabeling is not up-regulated in theses cases, correlating well with the failure of regeneration. Neurotrophin-3 (NT-3) and its receptor TrkC were not modified compared to controls (five cases). On the contrary, we observed in all cases a pronounced decrease in the number of fibers labeled for nerve growth factor (NGF) and insulin-like growth factor I (IGF-I), which were both approximately half of control values. This decrease could not be ascribed to the reduction in fiber density since it was also present in cases without fiber loss (isolated large fiber atrophy). The fact that only around 50% of fibers were stained, versus all fibers in controls, probably accounted for this decrease. It contrasted also with the normality of NGF and IGF-I immunolabeling in six cases of chronic inflammatory demyelinating neuropathy that were investigated in parallel. These results differ from those reported in experimental diabetic neuropathy, during which NT-3 is also decreased. A deficient supply of specific growth factors delivered by neuronal targets may be responsible for these neuropathies and their associated axonal cytoskeleton abnormalities.

Adult↗