Neurobiological abnormalities in the first few years of life in individuals later diagnosed with Autistic Spectrum Disorder : A review of recent data

Peer reviewedPublisher PD

Characterisation of microstructure, defect and high-cycle-fatigue behaviour in a stainless steel joint processed by brazing

We report the characterisation of microstructures and high-cycle-fatigue (HCF) properties of Type 304 stainless steel joints processed by brazing. Pure copper was applied as the filler metal for brazing at 1120 °C. A two-phase microstructure was obtained within the joint region: the star-shaped precipitates and copper matrix. The precipitates with an average size of 0.43 μm were rich in iron and chromium. A fixed orientation relationship was found between the precipitates and copper matrix. The joint exhibited much higher tensile strength and HCF life when compared to pure copper. The strength enhancement can be attributed to the presence of precipitates. Furthermore, the effect of joint interface roughness as well as defects was critically investigated. The joint interface roughness showed little influence on the HCF lives. Post-examinations revealed that fatigue crack initiation and propagation occurred entirely within the joint region, hence being consistent with the similar HCF lives regardless of the pre-defined interface roughness conditions. In addition, it was found that the HCF lives decreased exponentially with the increase of initial defect area. Fractography analysis revealed that fatigue striation spacings near the crack initiation zone increased with the increase of defect area, suggesting that the larger defects result in higher crack growth rate, hence shorten the overall fatigue life.</div

Improving the radiopacity of Fe–Mn biodegradable metals by magnetron-sputtered W–Fe–Mn–C coatings: Application for thinner stents

none9siIn this exploratory work, micrometric radiopaque W–Fe–Mn–C coatings were produced by magnetron sputtering plasma deposition, for the first time, with the aim to make very thin Fe–Mn stents trackable by fluoroscopy. The power of Fe–13Mn-1.2C target was kept constant at 400 W while that of W target varied from 100 to 400 W producing three different coatings referred to as P100, P200, P400. The effect of the increased W power on coatings thickness, roughness, structure, corrosion behavior and radiopacity was investigated. The coatings showed a power-dependent thickness and W concentration, different roughness values while a similar and uniform columnar structure. An amorphous phase was detected for both P100 and P200 coatings while γ-Fe, bcc-W and W3C phases found for P400. Moreover, P200 and P400 showed a significantly higher corrosion rate (CR) compared to P100. The presence of W, W3C as well as the Fe amount variation determined two different micro-galvanic corrosion mechanisms significantly changing the CR of coatings, 0.26 ± 0.02, 59.68 ± 1.21 and 59.06 ± 1.16 μm/year for P100, P200 and P400, respectively. Sample P200 with its most uniform morphology, lowest roughness (RMS = 3.9 ± 0.4 nm) and good radiopacity (∼6%) appeared the most suitable radiopaque biodegradable coating investigated in this study.openRavanbakhsh S.; Paternoster C.; Barucca G.; Mengucci P.; Gambaro S.; Lescot T.; Chevallier P.; Fortin M.-A.; Mantovani D.Ravanbakhsh, S.; Paternoster, C.; Barucca, G.; Mengucci, P.; Gambaro, S.; Lescot, T.; Chevallier, P.; Fortin, M. -A.; Mantovani, D

Abrasive elements and abrasion resistance tests for car seat upholstery

The weight of textile components in automobiles is expected to rise to 35 kg by 2020, and the average lifetime of a vehicle is about 12 years. Car seats are the most important part of the interior decoration, and polyester is the most widely used material in car seat covering. Abrasion resistance tests are used to quantify the duration of car seat upholstery in normal usage, and this is one of the most important requirements. Several testing methods, standards, and car producer specifications have been developed to define the abrasion resistance of specified materials, and pre-tests have been taken to identify parameters for this research. The objective of this study was to compare three abrasion tests with different abrasive elements using car seat upholstery structures. Comparison among abrasion testers and abrasive papers shows statistically significant differences. The relationship between weight loss and abrasion cycles can be modelled by regression equationsPostprint (published version

Reduced object related negativity response indicates impaired auditory scene analysis in adults with autistic spectrum disorder

Auditory Scene Analysis provides a useful framework for understanding atypical auditory perception in autism. Specifically, a failure to segregate the incoming acoustic energy into distinct auditory objects might explain the aversive reaction autistic individuals have to certain auditory stimuli or environments. Previous research with non-autistic participants has demonstrated the presence of an Object Related Negativity (ORN) in the auditory event related potential that indexes pre-attentive processes associated with auditory scene analysis. Also evident is a later P400 component that is attention dependent and thought to be related to decision-making about auditory objects. We sought to determine whether there are differences between individuals with and without autism in the levels of processing indexed by these components. Electroencephalography (EEG) was used to measure brain responses from a group of 16 autistic adults, and 16 age- and verbal-IQ-matched typically-developing adults. Auditory responses were elicited using lateralized dichotic pitch stimuli in which inter-aural timing differences create the illusory perception of a pitch that is spatially separated from a carrier noise stimulus. As in previous studies, control participants produced an ORN in response to the pitch stimuli. However, this component was significantly reduced in the participants with autism. In contrast, processing differences were not observed between the groups at the attention-dependent level (P400). These findings suggest that autistic individuals have difficulty segregating auditory stimuli into distinct auditory objects, and that this difficulty arises at an early pre-attentive level of processing

Reduced engagement with social stimuli in 6-month-old infants with later Autism Spectrum Disorder: a longitudinal prospective study of infants at high familial risk

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that affects more than 1% of the population, and close to 20% of prospectively studied infants with an older sibling with ASD. Although significant progress has been made in characterizing the emergence of behavioral symptoms of ASD, far less is known about the underlying disruptions to early learning. Recent models suggest that core aspects of the causal path to ASD may only be apparent in early infancy. Here, we investigated social attention in 6- and 12-month-old infants who did and did not meet criteria for ASD at 24 months using both cognitive and electrophysiological methods. We hypothesized that a reduction in attention engagement to faces would be associated with later ASD. Methods: In a prospective longitudinal design, we used measures of both visual attention (habituation) and brain function (event-related potentials to faces and objects) at 6 and 12 months, and investigated the relationship to ASD outcome at 24 months. Results: High-risk infants who met criteria for ASD at 24 months showed shorter epochs of visual attention, faster but less prolonged neural activation to faces, and delayed sensitization responses (increases in looking) to faces at 6 months; these differences were less apparent at 12 months. These findings are consistent with disrupted engagement of sustained attention to social stimuli. Conclusions: These findings suggest that there may be fundamental early disruptions to attention engagement that may have cascading consequences for later social functioning

Processamento neural de faces em crianças institucionalizadas com e sem perturbação de vinculação: um estudo de potenciais evocados

Dissertação de mestrado integrado em Psicologia (área de especialização de Psicologia Clínica)Nos últimos anos, diversos estudos de potenciais evocados (em inglês, Event Related Potentials – ERPs) mostraram que, desde idades muito precoces, as crianças com desenvolvimento típico são capazes de diferenciar a face da mãe de faces estranhas (Carver et al., 2003; de Haan & Nelson, 1997, 1999). No entanto, apenas dois estudos procuraram compreender os efeitos da institucionalização - uma experiência relacional atípica com efeitos sócio-emocionais adversos - no processamento neural da familiaridade de faces (Moulson, Westerlund, Fox, Zeanah, & Nelson, 2009; Parker & Nelson, 2005). Estes autores verificaram que, quer crianças institucionalizadas quer crianças não institucionalizadas eram capazes de discriminar faces familiares de faces não familiares, ainda que se constatasse hipoativação cortical no grupo de crianças institucionalizadas. Até à atualidade nenhum estudo com crianças institucionalizadas avaliou os padrões de atividade neural em função da familiaridade de faces considerando a presença das perturbações de vinculação. Neste sentido, este estudo pretende analisar o efeito da familiaridade de faces no processamento neural em: (1) crianças inseridas em contexto institucional; (2) crianças institucionalizadas com e sem perturbação de vinculação; (3) crianças institucionalizadas com perturbação de vinculação do tipo inibido e do tipo desinibido. Foram recolhidos os ERPs de 25 crianças, com idades compreendidas entre os 36 e os 70 meses (M = 55.96; DP = 11.43) e aplicada a Disturbances of Attachment Interview (DAI; Smyke & Zeanah, 1999) aos seus respetivos prestadores de cuidados. Onze crianças (44%) foram diagnosticadas com perturbação de vinculação (das quais sete (28%) do tipo inibido, três (12%) do tipo desinibido e uma (4%) de ambos os tipos), enquanto as restantes 14 (56%) não preencheram os critérios de diagnóstico. Os resultados obtidos sugerem que: a) crianças institucionalizadas revelam padrões de ativação neural atípicos, caracterizados pela relativa falta de discriminação ao nível da familiaridade de faces, que divergem dos dados previamente observados neste grupo de risco; b) crianças institucionalizadas com e sem perturbação de vinculação não se distinguem na forma como processam faces familiares e não familiares, observando-se, contudo, maior tendência para hipoativação cortical em crianças com perturbação de vinculação; c) a experiência de institucionalização parece ter maior impacto no processamento neural de faces em crianças com perturbação de vinculação do tipo desinibido1. Em geral, os dados obtidos sugerem que o processamento de informação social tende a estar sobretudo comprometido em crianças institucionalizadas com comportamentos perturbados de vinculação.In recent years, studies using event-related potential techniques (ERPs) have shown that, from early ages, typically developing children are able to discriminate their mothers’ faces from strangers’ faces (Carver et al., 2003; Dawson et al., 2002; de Haan & Nelson, 1997, 1999). Contrastingly, only two studies have sought to understand the effects of institutional rearing - an atypical relational experience with adverse socio-emotional effects - on the neural processing of face familiarity (Moulson, Westerlund, Fox, Zeanah, & Nelson, 2009; Parker & Nelson, 2005). These authors reported that both never-institutionalized children and children living in institutions were able to discriminate familiar from unfamiliar faces. Nevertheless, despite similar patterns, there was a cortical hypoarousal in the institutionalized group. To date, no study with institutionalized children analyzed the patterns of neural processing of face familiarity considering the presence of attachment disorders. Thus, the current study aims to examine the effects of face familiarity on the neural processing of: (1) children living in institutionalized settings; (2) institutionalized children with and without attachment disorder; (3) institutionalized children with inhibited and disinhibited types of attachment disorder. ERP data was collected for 25 children, aged between 36 and 70 months (M = 55.96; SD = 11.43). The Disturbances of Attachment Interview (DAI; Smyke & Zeanah, 1999) was administered to the caregiver of each child. Eleven children (44%) were diagnosed with an attachment disorder (seven (28%) with the inhibited type, three (12%) with the disinhibited type and one (4%) with both types), while the remaining 14 children (56%) did not meet this diagnosis. The results suggest that: a) institutionalized children show atypical patterns of neural activation, characterized by the relative lack of discrimination of face familiarity that differs from data previously observed in this risk group; b) children with and without attachment disorders do not differ in how they process familiar and unfamiliar faces; however, a tendency for cortical hypoarousal was discernible in the children with attachment disorder; c) the experience of institutionalization appears to have a greater impact on neural processing of faces in children with disinhibited type of attachment disorder2. In general, the data suggest that processing of social information tends to be more compromised in institutionalized children with disturbed attachment behaviors

Loss of H2A.Z Is Not Sufficient to Determine Transcriptional Activity of Snf2-Related CBP Activator Protein or p400 Complexes

The p400 and SRCAP (Snf2-related CBP activator protein) complexes remodel chromatin by catalyzing deposition of histone H2A.Z into nucleosomes. This remodeling activity has been proposed as a basis for regulation of transcription by these complexes. Transcript levels of p21 or Sp1 mRNAs after knockdown of p400 or SRCAP reveals that each regulates transcription of these promoters differently. In this study, we asked whether deposition of H2A.Z within specific nucleosomes by p400 or SRCAP dictates transcriptional activity. Our data indicates that nucleosome density at specific p21 or Sp1 promoter positions is not altered by the loss of either remodeling complex. However, knockdown of SRCAP or p400 reduces deposition of H2A.Z∼50% into all p21 and Sp1 promoter nucleosomes. Thus, H2A.Z deposition is not targeted to specific nucleosomes. These results indicate that the deposition of H2A.Z by the p400 or SRCAP complexes is not sufficient to determine how each regulates transcription. This conclusion is further supported by studies that demonstrate a SRCAPΔATP mutant unable to deposit H2A.Z has similar transcriptional activity as wild-type SRCAP

Personal Familiarity Influences the Processing of Upright and Inverted Faces in Infants

Infant face processing becomes more selective during the first year of life as a function of varying experience with distinct face categories defined by species, race, and age. Given that any individual face belongs to many such categories (e.g. A young Caucasian man's face) we asked how the neural selectivity for one aspect of facial appearance was affected by category membership along another dimension of variability. 6-month-old infants were shown upright and inverted pictures of either their own mother or a stranger while event-related potentials (ERPs) were recorded. We found that the amplitude of the P400 (a face-sensitive ERP component) was only sensitive to the orientation of the mother's face, suggesting that “tuning” of the neural response to faces is realized jointly across multiple dimensions of face appearance