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Developmental Age (developmental + age)
Selected AbstractsIn vitro model of full-thickness cartilage defect healingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 9 2007Hok Kei Tam Abstract Integration of the host,graft interface is implicated as one of the significant reasons for lack of complete healing in osteochondral grafting procedures for the treatment of cartilage lesions. We developed an in vitro model of cartilage healing in an osteochondral setting to study the effect of developmental age and collagenase treatment. Circular full-thickness vertical surgical incisions were made in the cartilaginous portion of cylindrical bovine osteochondral specimens. Two age groups were selected: Young (1,2 months old) and Older (6,8 months old). Cartilage integration across the surgical incisions was assessed by histologic analysis and by mechanical push-out testing at 2 and 4 weeks in culture. Histologic integration as well as peak push-out shear stress was significantly higher in older calf cartilage than in the young calf. Collagenase pretreatment in the older calf samples increased push-out strength at 4 weeks. Histologic integration correlated well with the mechanical push-out strength. Developmental age and time after injury affected the response to collagenase pretreatment. This osteochondral cartilage integration model can be useful to study factors that modulate healing of surgical replacement procedures in vitro, which may aid the development of newer approaches to promote the healing of cartilage defects. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1136,1144, 2007 [source] Development of dynamic stability in children's rhythmic movementDEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2009Eric G. James Abstract This study examined the hypothesis that the stability of rhythmic motor patterns increases with developmental age in children. Children aged 6 and 10 years and adults (18- to 23-year-olds) rocked back and forth at their preferred amplitude and frequency while seated on a wooden box placed atop a force platform. Participants performed the seated rocking task with their feet supported and unsupported. There was an age-related decrease in rocking frequency and variability of the rocking cycle period, while the stability of the rocking dynamics increased, as indexed by the standard deviation of the phase angle of center of pressure motion. The presence of foot support decreased the stability of the rocking dynamics and reduced cycle period variability in the children, but not the adults. The results revealed that increments of age are associated with an increase in the stability of rhythmic motor patterns even when environmental conditions are altered. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 465,473, 2009 [source] SPATIOTEMPORAL REORGANIZATION OF GROWTH RATES IN THE EVOLUTION OF ONTOGENYEVOLUTION, Issue 4 2000Miriam L. Zelditch Abstract. Heterochrony, evolutionary changes in rate or timing of development producing parallelism between ontogeny and phylogeny, is viewed as the most common type of evolutionary change in development. Alternative hypotheses such as heterotopy, evolutionary change in the spatial patterning of development, are rarely entertained. We examine the evidence for heterochrony and heterotopy in the evolution of body shape in two clades of piranhas. One of these is the sole case of heterochrony previously reported in the group; the others were previously interpreted as cases of heterotopy. To compare ontogenies of shape, we computed ontogenetic trajectories of shape by multivariate regression of geometric shape variables (i.e., partial warp scores and shape coordinates) on centroid size. Rates of development relative to developmental age and angles between the trajectories were compared statistically. We found a significant difference in developmental rate between species of Serrasalmus, suggesting that heterochrony is a partial explanation for the evolution of body shape, but we also found a significant difference between their ontogenetic transformations; the direction of the difference between them suggests that heterotopy also plays a role in this group. In Pygocentrus we found no difference in developmental rate among species, but we did find a difference in the ontogenies, suggesting that heterotopy, but not heterochrony, is the developmental basis for shape diversification in this group. The prevalence of heterotopy as a source of evolutionary novelty remains largely unexplored and will not become clear until the search for developmental explanations looks beyond heterochrony. [source] Age Recognition in Adults with Intellectual Disabilities: a Literature Review and an Exploratory StudyJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 3 2000Dorothy M. Bell The ability of children to classify accurately their own ages and the ages of others has been the subject of very limited research. However, the literature is largely in agreement on there being progressive increases in skill with chronological age, although there is disagreement on the age at which this ability becomes well developed. The processes look similar in the field of intellectual disabilities, although this area is extremely under-researched. Key factors may include age, the amount of time spent in institutions (e.g. long-term hospitals for people with intellectual disabilities), developmental level and IQ. The present paper provides a review of the relevant literature and an exploratory study investigating the age recognition of self and colleagues in a group of 20 adults with intellectual disability, some from within what has been a major hospital for people with intellectual disabilities and some from the wider community. Measures of age recognition using photographs, as well as standardized measures of intellectual ability and social adaptive behaviour, were administered, and correlations were found between the ability to recognize age in others and developmental age, and also IQ. Success on the task of age discrimination appears to be more likely if the IQ of the individual is around 60,65 or above, and if the person shows social adaptive behaviour equivalent to 8 or 9 years of age and over. Also included in the study was a task in which only the discrimination of whether the photographs were of adults or children was required, and this proved to be a simpler process for the participants. The present study also demonstrates some of the discriminative stimuli used by adults with intellectual disabilities to ascertain the approximate age of a person. [source] Attachment behaviour towards support staff in young people with intellectual disabilities: associations with challenging behaviourJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 7 2010J. C. De Schipper Abstract Background Attachment research has shown the importance of attachment behaviour for the prevention of dysregulated behaviour due to emotional distress. The support of an attachment figure may be especially important for people with intellectual disability (ID), because they are less adept in dealing with stressful situations on their own. Our purpose was to examine the role of support staff as targets of attachment behaviour for young people with ID by testing the hypothesis that young people who more often engage in attachment interactions with group care staff are less at risk for challenging behaviours. The study design included professional caregivers' report of young persons' attachment behaviour across different relationships to address the relationship-specific nature of attachment behaviour in a group care context. Methods Support staff rated attachment behaviour of 156 young participants with moderate to severe ID who were attending a group care setting. For each participant, we asked two members of the classroom support staff to fill out the Secure Base Safe Haven Observation list. One of them also rated challenging behaviour (Abberant Behavior Checklist). Results Young people who showed more secure attachment behaviour towards professional caregivers were less irritable, less lethargic and less stereotypic in their behaviour, even if we controlled for developmental age and Autism Spectrum Disorders. Two results point in the direction of relationship-specific attachment behaviour: the absence of high consistency in a person's attachment behaviour towards two different caregivers and the independent contribution of each of these relationships to explaining differences in lethargy and stereotypies. A certain preference in attachment behaviour towards specific caregivers was not associated with challenging behaviour. Conclusions Findings suggest that attachment behaviour may be part of young persons' adaptation to the stresses and challenges of group care. Furthermore, adaptation may be determined by the integration of relationships with support staff, because each relationship with a care staff member bears uniquely on challenging behaviour. [source] Symposium 1: Regulation of Neural Development by BMP and Activin Family MembersJOURNAL OF NEUROCHEMISTRY, Issue 2002J. A. Kessler The effects of BMP family members on stem cell lineage commitment depend upon the developmental age of the stem cell. BMP4 promotes apoptosis of early ventricular zone (VZ) stem cells, neuronal differentiation of later stage VZ cells, and astroglial differentiation of subventricular zone (SVZ) cells. BMP4 inhibits oligodendroglial lineage commitment at all stages of development. The effects of BMP4 in promoting commitment to a specific lineage reflect active suppression of alternate lineages by transcriptional inhibitors including ID and HEY family members and others. For example, BMP mediated increases in ID expression in SVZ stem cells suppress both oligodendroglial and neuronal differentiation. Similarly HEY 1 expression in SVZ cells suppresses neuronal differentiation, whereas HEYL expression by VZ cells inhibits glial differentiation and promotes neurogenesis. The differing effects of the BMPs on VZ and SVZ stem cells reflect also differences in the complement of transcription factors that are expressed. For example, VZ stem cells express high levels of neurogenin and HEY L whereas SVZ stem cells express lower levels of these factors but higher levels of HEY1. Thus lineage commitment by stem cells reflects interplay among stimulatory and inhibitory transcription factors, and responses to the BMPs depend upon the repertoire of transcription factors already expressed by the cell. [source] Differential expression of connexin 43 in the chick tangential vestibular nucleusJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2003Anastas Popratiloff Abstract The chick tangential nucleus is a major vestibular nucleus whose principal cells receive convergent inputs from primary vestibular and nonvestibular fibers and participate in the vestibular reflexes. During development, the principal cells gradually acquire the mature firing pattern in part by losing a specific potassium current around hatching (H). Here we focus on characterizing the expression of connexin 43 (Cx43), a gap junction protein found mainly between astrocytes in the mature brain. The astrocytic syncytium plays an important role in maintaining extracellular potassium ion balance in the brain. Accordingly, it is important to characterize the potential of this syncytium to communicate during the critical developmental age of hatching. Using fluorescence immunocytochemistry, we investigated whether Cx43 staining was concentrated in specific cellular compartments at H1 by applying well-known markers for astrocytes (glial fibrillary acidic protein; GFAP), oligodendrocytes (antimyelin), neurons (microtubule-associated protein 2), and synaptic terminals (synaptotagmin). GFAP-positive astrocytes and GFAP-negative nonneuronal cells around the principal cell bodies were labeled with Cx43, suggesting that Cx43 was expressed exclusively by nonneuronal cells near the neuronal elements. Next, the developmental pattern of expression of Cx43 was studied at embryonic day 16 (E16), H1, and H9. At E16, Cx43 was present weakly as random small clusters in the tangential nucleus, whereas, at H1, overall staining became localized, with increases in size, brightness, and number of immunostained clusters. Finally, at H9, Cx43 staining decreased, but cluster size and location remained unchanged. These results suggest that Cx43 is developmentally regulated with a peak at birth and is associated primarily with astrocytes and nonneuronal cells near the principal cell bodies. © 2003 Wiley-Liss, Inc. [source] In vitro model of full-thickness cartilage defect healingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 9 2007Hok Kei Tam Abstract Integration of the host,graft interface is implicated as one of the significant reasons for lack of complete healing in osteochondral grafting procedures for the treatment of cartilage lesions. We developed an in vitro model of cartilage healing in an osteochondral setting to study the effect of developmental age and collagenase treatment. Circular full-thickness vertical surgical incisions were made in the cartilaginous portion of cylindrical bovine osteochondral specimens. Two age groups were selected: Young (1,2 months old) and Older (6,8 months old). Cartilage integration across the surgical incisions was assessed by histologic analysis and by mechanical push-out testing at 2 and 4 weeks in culture. Histologic integration as well as peak push-out shear stress was significantly higher in older calf cartilage than in the young calf. Collagenase pretreatment in the older calf samples increased push-out strength at 4 weeks. Histologic integration correlated well with the mechanical push-out strength. Developmental age and time after injury affected the response to collagenase pretreatment. This osteochondral cartilage integration model can be useful to study factors that modulate healing of surgical replacement procedures in vitro, which may aid the development of newer approaches to promote the healing of cartilage defects. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1136,1144, 2007 [source] Sleep problems, sleepiness and daytime behavior in preschool-age childrenTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 12 2009Beth Goodlin-Jones Background:, Sleep problems are a common complaint of parents of preschool children. Children with neurodevelopmental disorders have even more disrupted sleep than typically developing children. Although disrupted nighttime sleep has been reported to affect daytime behavior, the pathway from sleep disruption to sleep problems, to impairments in daytime performance or behavior is not clear. This multi-method, preliminary study assessed this path in 68 children with autism, matched to 57 children with developmental delay without autism and 69 children developing typically. Methods:, Actigraphy, structured questionnaires, laboratory assessments, and parent reports were obtained in 194 children. Results:, Controlling for diagnosis and developmental age of the child, nighttime sleep problems determined by parent reports were significantly associated with decrements in daytime behavior, also measured by parent report instruments. However, actigraph-defined sleep problems and objective measures of daytime sleepiness were not associated with decrements in daytime performance. Conclusions:, Parent report measures substantiate relationships between disrupted sleep patterns and waking behavior. Further understanding of the pathway from sleep disorders to daytime sleepiness and decrements in waking performance, however, may require more rigorous methods of assessment such as polysomnography and the multiple sleep latency test. [source] Accelerated embryonic development associated with increased risk of neural tube defects induced by maternal diet in offspring of SELH/Bc mice,BIRTH DEFECTS RESEARCH, Issue 10 2008Katharine L. Stoate Abstract BACKGROUND: The SELH/Bc mouse strain has a high risk of the NTD, exencephaly, caused by multifactorial genetics. All SELH/Bc embryos have delayed elevation of neural folds; some never elevate (future exencephalics). Maternal diets affect SELH/Bc exencephaly rates: 25,35% on Purina Diet 5015 versus 5,10% on Purina Diet 5001. We hypothesized that in SELH/Bc, the diets affect maternal blood glucose and embryonic developmental rate. METHODS: We compared mice fed the two diets. On GD 9.4 we tested maternal blood glucose and examined embryos for developmental age (somite count) and cranial neural fold morphology. We observed GD 14 exencephaly rates. RESULTS: Diet 5015 caused fivefold more exencephaly (40 vs. 7% on GD 14), significantly higher mean maternal blood glucose in replicate experiments (6.3 vs. 5.5, p < .05; 6.3 vs. 5.3 mmol/L, p < .05), and significantly higher mean litter somite count on GD 9.4 (18.4 vs. 15.0, p < .05; 16.7 vs. 14.4 somites, p < .05). Among midrange embryos (15,16 somites), embryos from Diet 5015 were significantly shifted to earlier stages of midbrain fold morphology and had significantly more distance between the tips of the folds (p < .05). CONCLUSIONS: In SELH/Bc mice, the 5015 diet causes higher maternal blood glucose, a faster overall embryonic developmental rate during neural tube closure, and delayed midbrain fold elevation relative to overall development. This pattern suggests that maternal dietary effects that modestly increase embryonic growth rate may exacerbate a lack of coordination between genetically delayed neural folds and normally developing underlying tissues, increasing risk of NTD. Birth Defects Research (Part A), 2008. © 2008 Wiley-Liss, Inc. [source] The Biochemistry of Drug Metabolism , An IntroductionCHEMISTRY & BIODIVERSITY, Issue 10 2009Abstract This review on intra-individual factors affecting drug metabolism completes our series on the biochemistry of drug metabolism. The article presents the molecular mechanisms causing intra-individual differences in enzyme expression and activity. They include enzyme induction by transcriptional activation and enzyme inhibition on the protein level. The influencing factors are of physiological, pathological, or external origin. Tissue characteristics and developmental age strongly influence enzyme-expression patterns. Further influencing factors are pregnancy, disease, or biological rhythms. Xenobiotics, drugs, constituents of herbal remedies, food constituents, ethanol, and tobacco can all influence enzyme expression or activity and, hence, affect drug metabolism. [source] What helps when it hurts: children's views on pain reliefCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 4 2008L. S. Franck Abstract Background Previous studies have focused on children's views of sources of pain and only secondarily explored their views on pain-relief strategies. Methods An exploratory cross-sectional descriptive design and ,draw and write' technique were used to investigate what children think helps them when they have pain. Results The sample (n = 71) was comprised of 33% boys and 67% girls, with an age range of 4,16 years (mean ± SD: 9.25 ± 3.04). Four overarching themes were derived that were common to both the texts and drawings: ,People who help', ,What I do that helps', ,What other people do that helps' and ,Things that help'. Children also described their emotional reactions to pain or pain relief. Multiple themes were represented in most of the texts and drawings. There were few differences in the themes present in the children's texts and drawings based on developmental age and no differences based on gender. Conclusions Children across the three developmental age groups view themselves as active agents in pain relief. Although less than half of the children described specific behaviours they had taken, almost all children indicated their active role as the central figure in relation to use of objects or the actions of others. [source] A qualitative investigation of school-aged children's answers to items from a generic quality of life measureCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 1 2007J. Cremeens Abstract Background, The development of instruments to measure child self-reported quality of life (QOL) is dependent on whether children can understand the concepts behind items. Researchers need more information on how children are interpreting and answering items. This paper aims to investigate the strategies school-aged children use to answer QOL items. Methods, A generic 30-item QOL measure (the TedQL) was administered to 266 healthy children (5,6, 7,9 years old). Children were asked to ,think aloud' while answering a selection of 10 TedQL items (n = 4 ability, n = 4 social, n = 2 mood items), and their responses were recorded verbatim. Results, The strategies children reported using when answering items were coded into five categories: (1) social comparisons; (2) stable character references; (3) concrete examples; (4) other reasons; or (5) no reason given. Concrete examples were used most frequently by children. Strategy type was dependent on age, with 7,9-year-olds reporting social comparisons and concrete examples more frequently than 5,6-year-olds. Five-to-six-year-olds gave no reasons for their response choices more frequently than 7,9-year-olds. Strategy type also differed by item type, with social comparisons used more frequently for ability items, and stable character references for social items. However, concrete examples were used consistently highly across ability and social items. Conclusions, Children aged 5,9 years most commonly report using concrete examples of specific instances when answering QOL items. However, strategy use varies as a function of age and types of items. Our results highlight the importance of keeping in mind children's developmental age when interpreting responses from child QOL instruments. [source] Biglycan binds to ,- and ,-sarcoglycan and regulates their expression during development,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2006Michael S. Rafii The dystrophin-associated protein complex (DAPC), which links the cytoskeleton to the extracellular matrix, is essential for muscle cell survival, and is defective in a wide range of muscular dystrophies. The DAPC contains two transmembrane subcomplexes,the dystroglycans and the sarcoglycans. Although several extracellular binding partners have been identified for the dystroglycans, none have been described for the sarcoglycan subcomplex. Here we show that the small leucine-rich repeat (LRR) proteoglycan biglycan binds to ,- and ,-sarcoglycan as judged by ligand blot overlay and co-immunoprecipitation assays. Our studies with biglycan-decorin chimeras show that ,- and ,-sarcoglycan bind to distinct sites on the polypeptide core of biglycan. Both biglycan proteoglycan as well as biglycan polypeptide lacking glycosaminoglycan (GAG) side chains are components of the dystrophin glycoprotein complex isolated from adult skeletal muscle membranes. Finally, our immunohistochemical and biochemical studies with biglycan null mice show that the expression of ,- and ,-sarcoglycan is selectively reduced in muscle from young (P14-P21) animals, while levels in adult muscle (,P35) are unchanged. We conclude that biglycan is a ligand for two members of the sarcoglycan complex and regulates their expression at discrete developmental ages. J. Cell. Physiol. 209: 439,447, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||