ABSTRACT
Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.
Subject(s)
Cell Movement/physiology , Embryo, Mammalian/embryology , Embryo, Mammalian/ultrastructure , Gastrointestinal Tract/embryology , Gastrointestinal Tract/ultrastructure , Neural Crest/embryology , Neural Crest/ultrastructure , Animals , Chick Embryo , Collagenases/metabolism , Extracellular Matrix/metabolism , Extracellular Matrix/ultrastructure , Mice , Microscopy, Atomic ForceABSTRACT
BACKGROUND: The Behaviour Problems Inventory-Short Form (BPI-S) is a spin-off of the BPI-01 that was empirically developed from a large BPI-01 data set. In this study, the reliability and factorial validity of the BPI-S was investigated for the first time on newly collected data from adults with intellectual disabilities. METHODS: The sample consisted of 232 adults with intellectual disabilities who represented all levels of intellectual functioning. They were recruited at several day programs in the USA (n = 148) and the UK (n = 84). RESULTS: We found acceptable reliability in terms of internal consistency, inter-rater agreement and test-retest reliability. Confirmatory factor analysis validated the three BPI-S subscale structure. CONCLUSIONS: We corroborated the factor structure underly-ing the three subscales and found the BPI-S to have adequate to good psychometric properties in a newly collected sample of adults with intellectual disabilities.
Subject(s)
Intellectual Disability/diagnosis , Intellectual Disability/psychology , Problem Behavior/psychology , Surveys and Questionnaires/standards , Adolescent , Adult , Aged , Aggression/psychology , Factor Analysis, Statistical , Female , Humans , Male , Middle Aged , Psychometrics , Reproducibility of Results , Self-Injurious Behavior/diagnosis , Self-Injurious Behavior/psychology , Severity of Illness Index , United Kingdom , United States , Young AdultABSTRACT
Studies of the sites and mechanisms involved in mammalian respiratory rhythm generation point to two clusters of rhythmic neurons forming a coupled oscillator network within the brainstem. The location of these oscillators, the pre-Bötzinger complex (preBötC) at vagal level, and the para-facial respiratory group at facial level, probably result from regional patterning schemes specifying neural types in the hindbrain during embryogenesis. Here, we report evidence that the preBötC oscillator (i) is first active at embryonic stages, (ii) originates in the post-otic hindbrain neural tube and (iii) requires the glutamate vesicular transporter 2 for rhythm generation.
