Pubmed du 26/05/09

mercredi 27 mai 2009

1. De Felice C, Ciccoli L, Leoncini S, Signorini C, Rossi M, Vannuccini L, Guazzi G, Latini G, Comporti M, Valacchi G, Hayek J. Systemic oxidative stress in classic Rett syndrome. Free Radic Biol Med ;2009 (May 20)

Rett syndrome (RS), a progressive severe neurodevelopmental disorder mainly caused by de novo mutations in the X-chromosomal methyl-CpG-binding protein 2 (MeCP2) gene encoding for the transcriptional regulator methyl CpG binding protein 2 (MeCP2), is a leading cause of mental retardation with autistic features in females. However, its pathogenesis remains incompletely understood, and no effective therapy is available to date. We hypothesized that a systemic oxidative stress may play a key role in the pathogenesis of classic RS. Patients with classic RS (n = 59) and control subjects (n = 43) were evaluated. Oxidative stress markers included intra-erythrocyte non-protein-bound iron (NPBI, i.e., free iron), plasma NPBI, F(2)-isoprostanes (F(2)-IsoPs, as free, esterified and total forms) and protein carbonyls. Lung ventilation/perfusion (V/Q) ratio was assessed using a portable gas analyzer, and RS clinical severity was evaluated using standard scales. Significantly increased intra-erythrocyte NPBI (x 2.73-folds), plasma NPBI (x 6.0), free F(2)-IsoPs (x 1.85), esterified F(2)-IsoPs (x 1.69), total F(2)-IsoPs (x 1.66) and protein carbonyls (x 4.76) concentrations were evidenced in RS subjects, and associated with reduced (-10.53%) arterial oxygen levels as compared to controls. Biochemical evidence of oxidative stress was related to clinical phenotype severity and lower peripheral and arterial oxygen levels. Pulmonary V/Q mismatch was found in the majority of the RS population. These data identify hypoxia-induced oxidative stress as a key factor in the pathogenesis of classic RS, and suggest new therapeutic approaches based on oxidative stress modulation.

2. Fodstad JC, Matson JL, Hess J, Neal D. Social and communication behaviours in infants and toddlers with autism and pervasive developmental disorder-not otherwise specified. Dev Neurorehabil ;2009 (Jun) ;12(3):152-157.

PURPOSE : Autism Spectrum Disorders (ASD) are a group of conditions characterized by symptoms that onset in early childhood. Deficits in social skills and communication are two of the core features of ASD and, if not remediated, can lead to poor long-term outcomes. Few researchers have examined characteristics of social skills and communication in infants with ASD. METHOD : The social skills and communicative ability of 886 infants and toddlers 17-37 months of age with autism, PDD-NOS or ’at risk’ for other developmental delays were evaluated using the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT). A Kruskal-Wallis test with follow-up Mann-Whitney tests were used to test for significance. RESULTS : Infants and toddlers with autism, followed by PDD-NOS, had greater social and communication deficits than children ’at risk’ for developmental delays. Items which distinguished between these diagnostic groups were determined. CONCLUSIONS : Outcomes suggest that social and communication deficits can be identified at early ages in a population of developmentally delayed toddlers. Implications are that pinpointing emerging social and communicative autistic traits earlier will allow for more accurate assessment and diagnosis in infants with ASD. This translates into earlier intervention and more effective treatment practices.

3. Matson JL, Dempsey T, Fodstad JC. Stereotypies and repetitive/restrictive behaviours in infants with autism and pervasive developmental disorder. Dev Neurorehabil ;2009 (Jun) ;12(3):122-127.

PURPOSE : Autism Spectrum Disorders (ASD) are characterized by severe and debilitating symptoms including stereotyped and repetitive behaviours. Stereotypies and repetitive behaviours constitute core features of ASD and markedly impede attempts to remediate the disorder. Little previous research has examined characteristics of the core features of ASD in infants. METHOD : In the present study, 760 infants with autism, PDD-NOS or no diagnosis of ASD but at risk for other developmental delays or physical disabilities were evaluated with respect to the nature and extent of their stereotyped and ritualistic behaviour using the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT). A Kruskal-Wallis test with follow-up Mann-Whitney tests were employed to test for significant differences. RESULTS : Infants with autism evinced the highest amount of stereotypic behaviour, followed by those with PDD-NOS and atypical development. A sub-set of BISCUIT items could accurately predict diagnostic group membership. CONCLUSIONS : These data suggest that many core features of ASD are distinct and can be reliably identified early in life. The potential early identification of these behavioural challenges could lead to earlier intervention practices and symptom alleviation for children in this population.

4. Mechling LC, Gast DL, Seid NH. Using a Personal Digital Assistant to Increase Independent Task Completion by Students with Autism Spectrum Disorder. J Autism Dev Disord ;2009 (May 23)

In this study, a personal digital assistant (PDA) with picture, auditory, and video prompts with voice over, was evaluated as a portable self-prompting device for students with autism spectrum disorder (ASD). Using a multiple probe design across three cooking recipes and replicated with three students with ASD, the system was tested for its effectiveness in increasing independent performance across the multiple step tasks. In addition, data were recorded for the number and types of prompts used by the students across time. Results indicate that the students with ASD were able to adjust the prompt levels used on the PDA and to maintain their ability to use the device to independently complete recipes over time.

5. Nazarali N, Glazebrook CM, Elliott D. Movement Planning and Reprogramming in Individuals With Autism. J Autism Dev Disord ;2009 (May 23)

Two experiments explored how individuals with and without autism plan and reprogram movements. Participants were given partial or complete information regarding the location of the upcoming manual movement. In Experiment 1, direct information specified the hand or direction of the upcoming movement. These results replicated previous reports that participants with autism utilize advance information to prepare their movements in the same manner as their chronologically age matched peers. Experiment 2 examined how individuals respond to an unexpected change in the movement requirements. Participants received advance information about the hand and direction of the upcoming movement. On 20% of the trials participants needed to adjust either the hand or direction they had prepared. Overall, the individuals with autism had difficulty reprogramming already planned movements, particularly if a different effector was required.

6. Perez Velazquez JL, Barcelo F, Hung Y, Leshchenko Y, Nenadovic V, Belkas J, Raghavan V, Brian J, Garcia Dominguez L. Decreased brain coordinated activity in autism spectrum disorders during executive tasks : Reduced long-range synchronization in the fronto-parietal networks. Int J Psychophysiol ;2009 (May 21)

Current theories of brain function propose that the coordinated integration of transient activity patterns in distinct brain regions is the essence of brain information processing. The behavioural manifestations of individuals with autism spectrum disorders (ASD) suggest that their brains have a different style of information processing. Specifically, a current trend is to invoke functional disconnection in the brains of individuals with ASD as a possible explanation for some atypicalities in the behaviour of these individuals. Our observations indicate that the coordinated activity in brains of children with autism is lower than that found in control participants. Disruption of long-range phase synchronization among frontal, parietal and occipital areas was found, derived from magnetoencephalographic (MEG) recordings, in high-functioning children with ASD during the performance of executive function tasks and was associated with impaired execution, while enhanced long-range brain synchronization was observed in control children. Specifically, a more significant prefrontal synchronization was found in control participants during task performance. In addition, a robust enhancement in synchrony was observed in the parietal cortex of children with ASD relative to controls, which may be related to parietal lobe abnormalities detected in these individuals. These results, using synchronization analysis of brain electrical signals, provide support for the contention that brains of individuals with autism may not be as functionally connected as controls, and may suggest some therapeutic interventions to improve information processing in specific brain areas, particularly prefrontal cortices.

7. Waterhouse L. Autism is a Portmanteau Syndrome. Neuropsychol Rev ;2009 (May 26)


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