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Adult Levels (adult + level)
Selected AbstractsThe development of change blindness: children's attentional priorities whilst viewing naturalistic scenesDEVELOPMENTAL SCIENCE, Issue 3 2009S. Fletcher-Watson Change blindness describes the surprising difficulty of detecting large changes in visual scenes when changes occur during a visual disruption. In order to study the developmental course of this phenomenon, a modified version of the flicker paradigm, based on Rensink, O'Regan & Clark (1997), was given to three groups of children aged 6,12 years and to a group of adults. This paradigm tested the ability to detect single colour, presence/absence and location changes of both high and low semantic importance in a complex scene. Semantically important changes were detected more quickly and accurately than less semantically important changes, by all age groups, indicating that children had the same attentional priorities as adults. Older children achieved more efficient and accurate detection of changes than younger children and reached almost adult level at 10,12 years old. These improvements parallel age-related developments in attention and visual perception. [source] In vitro measurement of post-natal changes in proliferating satellite cell frequency during rat muscle growthANIMAL SCIENCE JOURNAL, Issue 2 2010Takahiro SUZUKI ABSTRACT Satellite cells, resident myogenic stem cells found in postnatal skeletal muscle, are most abundant during early postnatal development and sharply decline in frequency thereafter to adult levels in mice and rats. Therefore, postnatal changes in satellite cell mitotic activities are important aspects for further understanding a muscle growth strategy. In large meat-production animals, however, the traditional in vivo proliferation assay may be less realistic because it requires intra-peritoneal (ip) injection of huge dosage of mutagenic nucleosides, 3H-labeled thymidine or bromodeoxyuridine (BrdU), at each age-time of sacrifice. We report in the present pilot study using rats that in vivo proliferation activity of satellite cells can be evaluated by an in vitro BrdU-incorporation assay in early cultures. Briefly, satellite cells were prepared from upper hind-limb and back muscles and maintained for 24 h with imposing by BrdU addition for the last 2 h, followed by the regular immunocytochemistry for determining BrdU-incorporated cell percentage. This in vitro assay demonstrated a rapid decrease in proliferating satellite cell frequency to the adult level during about 3-month period after birth, and yielded a high correlation to the measurements by the in vivo BrdU ip-injection method during the postnatal period examined from day-2 to month-11. The in vitro proliferation assay may be further adaptable for large domestic animals by the combination with a muscle biopsy technique that enables age-interval sampling from the same growing animals. [source] Identification of prostaglandin E2 receptors mediating perinatal masculinization of adult sex behavior and neuroanatomical correlatesDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2008Christopher L. Wright Abstract Prostaglandin E2 (PGE2) mediates the organization of male rat sexual behavior and medial preoptic area (MPOA) neuroanatomy during a sensitive perinatal window. PGE2 is up-regulated in response to estradiol, and initiates a two-fold increase in dendritic spines densities on neurons. All the four receptors for PGE2 and EP1-4 are present in developing POA, a critical region controlling male sexual behavior. Previous studies explored that EP receptors are involved in PGE2-induction of neonatal levels of spinophilin protein, a surrogate marker for dendritic spine formation, but did not assess behavioral masculinization. Here, we used two approaches, suppression of EP receptor expression with antisense oligonucleotides and activation of EP receptors with selective agonists, to test which receptors are necessary and sufficient, respectively, for the effects of PGE2 on behavior and neuronal morphology. In female rats, neonatal treatment with antisense oligonucleotides against EP2 or EP4 but not EP1 or EP3 completely prevented the expression of adult behavior organized by PGE2 exposure. The effects of ONO-DI-004, ONO-AE-259-01, ONO-AE-248, and ONO-AE1-329 (EP1-4 agonists respectively) were equivalent to PGE2 treatment, which suggests activating any EP receptor neonatally suffices in masculinizing sex behavior. When given alone, not all EP agonists increased neonatal POA spinophilin levels; yet giving each agonist neonatally increased adult levels. Moreover, adult spinophilin levels significantly correlated with two measures of male sexual behavior. The body of evidence suggests that EP2 and EP4 are both necessary and sufficient for PGE2-induced masculinization of sex behavior, whereas EP1 and EP3 provide redundant roles. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Switching between spatial stimulus,response mappings: a developmental study of cognitive flexibilityDEVELOPMENTAL SCIENCE, Issue 4 2004Eveline A. Crone Four different age groups (8,9-year-olds, 11,12-year-olds, 13,15-year-olds and young adults) performed a spatial rule-switch task in which the sorting rule had to be detected on the basis of feedback or on the basis of switch cues. Performance errors were examined on the basis of a recently introduced method of error scoring for the Wisconsin Card Sorting Task (WCST; Barcelo & Knight, 2002). This method allowed us to differentiate between errors due to failure-to-maintain-set (distraction errors) and errors due to failure-to-switch-set (perseverative errors). The anticipated age differences in performance errors were most pronounced for perseverative errors between 8,9 years and 11,12 years, but for distraction errors adult levels were not reached until 13,15 years. These findings were interpreted to support the notion that set switching and set maintenance follow distinct developmental trajectories. [source] Human mid-gestation amniotic fluid contains interleukin-16 bioactivityIMMUNOLOGY, Issue 4 2009Catherine A. Thornton Summary CD4-positive cells are detectable in the human fetal gastrointestinal tract from 11 weeks of gestation. Interleukin-16 (IL-16) is a chemoattractant for CD4+ cells and, via fetal swallowing of amniotic fluid, could mediate the influx of CD4+ cells into the fetal gut. We have shown that IL-16 was detectable in human amniotic fluid at 16,18 weeks of gestation (mid-pregnancy) but was not detectable at term (late pregnancy; > 37 weeks of gestation). Similarly, mid-pregnancy, but not late pregnancy, amniotic fluid contained chemotactic activity for CD4+ T cells, this activity was reduced by 58% in the presence of a neutralizing anti-IL-16 antibody. The levels of IL-16 in fetal plasma at 16,24 weeks of gestation were very high, and decreased significantly by 25,36 weeks but at > 37 weeks remained significantly higher than adult levels. IL-16 transcripts were detectable in whole tissue extracts of fetal gut, skin and placenta but not in amniocytes, and IL-16 immunoreactivity was detectable in cells within the lamina propria of the fetal gut and within the skin, where it was associated with the basement membrane. Neither IL-16 levels nor chemotactic activity for CD4+ T cells in mid-pregnancy amniotic fluid was related to atopic outcomes at 1 year of age. IL-16 might have an important role in the early development of the human immune system and/or in regulating fetal and maternal immunological responsiveness during pregnancy. [source] Variation in the development of postcranial robusticity: an example from Çatalhöyük, TurkeyINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 3 2007L. W. Cowgill Abstract While the study of variation in adult postcranial robusticity has a long history, few analyses have examined the acquisition of postcranial robusticity within an ontogenetic context. This research evaluates differences in the ontogenetic trajectories of immature femora from three samples, in order to assess the point at which differences in levels of adult postcranial robusticity arise during development. Femoral midshaft cross-sectional properties were compared between three diverse samples: Neolithic agriculturalists from Çatalhöyük, Turkey (n,=,42); Byzantine agriculturalists from Çatalhöyük, Turkey (n,=,24); and urban Americans from the Denver Growth Study (n,=,151). While the two adult samples from Çatalhöyük do not differ statistically, both Neolithic and Byzantine adults have relatively larger cortical and total areas than the American urban adults, and these differences are clearly established by the age of six. In addition, by the age of three, individuals from the Denver Growth Study have already attained a greater percentage of their adult length, total area, and cortical area relative to those in both the Neolithic and Byzantine samples. These results indicate that the differing levels of postcranial robusticity characterising adult populations appear relatively early during development, and that populations vary in the rate and pattern through which adult levels of postcranial robusticity are achieved. Copyright © 2007 John Wiley & Sons, Ltd. [source] Postnatal development of 11,-hydroxysteroid dehydrogenase type 1 in the rat hippocampusJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2002S.L. Wan Abstract Glucocorticoids (GCs) have important actions in the hippocampus of the brain, where their access to glucocorticoid receptor (GR) is increased by 11,-hydroxysteroid dehydrogenase type 1 (11,-HSD1). 11,-HSD1 converts biologically inactive 11-dehydrocorticosterone into active corticosterone. However, the postnatal development of 11,-HSD1 in the hippocampus is not properly understood. In this study, the postnatal distribution and development of 11,-HSD1 in the hippocampus of the rat brain was studied with immunohistochemistry and Western blot analysis. Results showed that abundant 11,-HSD1 immunoreactive substance (ir-11,-HSD1) was present in the hippocampus. There were homogeneous distributions of 11,-HSD1 in the hippocampal CA1, CA2, CA3, CA4 regions and the dentate gyrus at postnatal days 1, 3, and 7. Interestingly, the developmental distribution of GR in the hippocampus followed the same pattern as 11,-HSD1. Western blot analysis demonstrated that a higher level of expression of 11,-HSD1 in the hippocampus was found in the first 2 weeks of life. The expressions of 11,-HSD1 started to drop to adult levels at about postnatal day 15 both in the hippocampus and in other brain areas. These results suggest that the higher expression of 11,-HSD1 in the neonatal hippocampus may be important for the maturation of the central nervous system mediated by GCs through GR. © 2002 Wiley-Liss, Inc. [source] Patterns of Ethanol Intake in Preadolescent, Adolescent, and Adult Wistar Rats Under Acquisition, Maintenance, and Relapse-Like ConditionsALCOHOLISM, Issue 4 2009David García-Burgos Background:, Animal behavioral models of voluntary ethanol consumption represent a valuable tool to investigate the relationship between age and propensity to consume alcohol using an experimental methodology. Although adolescence has been considered as a critical age, few are the studies that consider the preadolescence age. This study examines the ethanol consumption/preference and the propensity to show an alcohol deprivation effect (ADE) after a short voluntary ethanol exposure from a developmental perspective. Methods:, Three groups of heterogeneous Wistar rats of both sexes with ad libitum food and water were exposed for 10 days to 3 ethanol solutions at 3 different ontogenetic periods: preadolescence (PN19), adolescence (PN28), and adulthood (PN90). Ethanol intake (including circadian rhythm), ethanol preference, water and food consumption, and ADE were measured. Results:, During the exposure, the 3 groups differed in their ethanol intake; the greatest amount of alcohol (g/kg) was consumed by the preadolescent rats while the adolescents showed a progressive decrease in alcohol consumption as they approached the lowest adult levels by the end of the assessed period. The pattern of ethanol consumption was not fully explained in terms of hyperphagia and/or hyperdipsia at early ages, and showed a wholly circadian rhythm in adolescent rats. After an abstinence period of 7 days, adult rats showed an ADE measured both as an increment in ethanol consumption and preference, whereas adolescent rats only showed an increment in ethanol preference. Preadolescent rats decreased their consumption and their preference remained unchanged. Conclusions:, In summary, using a short period of ethanol exposure and a brief deprivation period the results revealed a direct relationship between chronological age and propensity to consume alcohol, being the adolescence a transition period from the infant to the adult pattern of alcohol consumption. Preadolescent animals showed the highest ethanol consumption level. The ADE was only found in adult animals for both alcohol consumption and preference, whereas adolescents showed an ADE only for preference. No effect of sex was detected in any phase of the experiment. [source] Urinary chemosignals in giant pandas (Ailuropoda melanoleuca): seasonal and developmental effects on signal discriminationJOURNAL OF ZOOLOGY, Issue 3 2004A. M. White Abstract As a solitary species, giant pandas Ailuropoda melanoleuca have a chemical communication system that allows for avoidance with conspecifics throughout most of the year and facilitates breeding during their brief reproductive period. To date, most studies have focused on adults during the breeding season, but much remains to be learned about developmental and seasonal effects on chemical communication. Here, using odour discrimination methodology, we examine these contextual influences on chemosignalling in giant pandas for the first time. During the breeding season both adult and subadult giant pandas overtly discriminated conspecific sex using chemical cues in urine. Male urine was consistently investigated more than female urine by pandas across all age-sex categories. This preference for male urine was observed for both adult and subadult urine donors, indicating that adult levels of reproductive hormones are not necessary for the production of sex-specific urinary odour cues. By contrast, giant pandas did not overtly discriminate sex during the non-breeding season. This finding underscores that negative results for discrimination studies need to be interpreted with caution, as many contextual factors may influence overt expression of this ability. Evidence points to seasonal changes in motivation, rather than in the availability of sex-specific chemical cues in urine, as the causal factor for changing odour discrimination patterns. These and other findings are discussed in the light of the potential role that discrimination of odour plays in the regulation of competitive and reproductive interactions in nature. [source] Stable carbon and nitrogen isotope values of bone and teeth reflect weaning age at the Medieval Wharram Percy site, Yorkshire, UKAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2002M.P. Richards Abstract We report on the measurements of carbon and nitrogen stable isotopes of both bone and teeth from a single site and population (Medieval Wharram Percy), undertaken to explore variations due to weaning in a past population. There have been a number of recent studies of weaning using ,15N values of ribs, and we indicate a number of assumptions that must be met before the results of such studies can be correctly interpreted. We found that rib collagen ,15N values decrease to adult levels after age 2 years, indicating that weaning occurred at or before this age. Rib collagen ,13C values are also more enriched than adult ,13C values before age 2 years, and we argue that this is due to the so-called "carnivore" effect in ,13C. We measured teeth and rib ,15N values from the same individuals and found that for individuals up to age 11 years, tooth dentine ,15N is higher than adult rib ,15N values, indicating that the dentine was formed during breast-feeding and that there was almost no turnover of dentine since. We observed some decrease in ,13C and ,15N rib values, compared to adult rib and teeth values, for the few years after weaning that may relate to a theoretically predicted physiological nitrogen imbalance during this period of rapid growth, but this is more likely due to a childhood diet (up to age 9) which was isotopically different from later diet, possibly consisting of a greater proportion of plant foods. Am J Phys Anthropol 119:205,210, 2002. © 2002 Wiley-Liss, Inc. [source] In vitro measurement of post-natal changes in proliferating satellite cell frequency during rat muscle growthANIMAL SCIENCE JOURNAL, Issue 2 2010Takahiro SUZUKI ABSTRACT Satellite cells, resident myogenic stem cells found in postnatal skeletal muscle, are most abundant during early postnatal development and sharply decline in frequency thereafter to adult levels in mice and rats. Therefore, postnatal changes in satellite cell mitotic activities are important aspects for further understanding a muscle growth strategy. In large meat-production animals, however, the traditional in vivo proliferation assay may be less realistic because it requires intra-peritoneal (ip) injection of huge dosage of mutagenic nucleosides, 3H-labeled thymidine or bromodeoxyuridine (BrdU), at each age-time of sacrifice. We report in the present pilot study using rats that in vivo proliferation activity of satellite cells can be evaluated by an in vitro BrdU-incorporation assay in early cultures. Briefly, satellite cells were prepared from upper hind-limb and back muscles and maintained for 24 h with imposing by BrdU addition for the last 2 h, followed by the regular immunocytochemistry for determining BrdU-incorporated cell percentage. This in vitro assay demonstrated a rapid decrease in proliferating satellite cell frequency to the adult level during about 3-month period after birth, and yielded a high correlation to the measurements by the in vivo BrdU ip-injection method during the postnatal period examined from day-2 to month-11. The in vitro proliferation assay may be further adaptable for large domestic animals by the combination with a muscle biopsy technique that enables age-interval sampling from the same growing animals. [source] Cholinergic and oxidative stress mechanisms in sudden infant death syndromeACTA PAEDIATRICA, Issue 11 2009Anne Dick Abstract Aim:, To determine whether biochemical parameters of cholinergic and oxidative stress function including red cell acetylcholinesterase (AChE), serum/plasma thyroglobulin, selenium, iron, ferritin, vitamins C, E, and A affect risk in apparent life-threatening event (ALTE), sudden infant death syndrome (SIDS), and sudden unexpected death in infancy (SUDI). To assess these biochemical parameters as a function of age; and for influence of pharmacology and epidemiology, including infant health, care, and feeding practices. Methods:, A multicentre, case,control study with blood samples from 34 ALTE and 67 non-ALTE (control) infants matched for age, and 30 SIDS/SUDI and four non-SIDS/non-SUDI (post-mortem control) infants. Results:, Levels/activity of the biochemical parameters were not significantly different in ALTE vs. control infants, with the exception of higher vitamin C levels in the ALTE group (p = 0.009). In ALTE and control groups, AChE and thyroglobulin levels increased and decreased respectively from birth to attain normal adult levels from 6 months. Levels of iron and ferritin were higher in the first 6 month period for all infant groups studied, intersecting with vitamin C levels peaking around 4 months of age. Conclusion:, Lower AChE levels and higher combined levels of iron and vitamin C in the first 6 months of life may augment cholinergic and oxidative stress effect, particularly at the age when SIDS is most prevalent. This may contribute to risk of ALTE and SIDS/SUDI events during infancy. [source] Are Young Children Susceptible to the False,Memory Illusion?CHILD DEVELOPMENT, Issue 5 2002C.J. Brainerd False memories have typically been found to be more common during early childhood than during later childhood or adulthood. However, fuzzy,trace theory makes the counterintuitive prediction that some powerful forms of adult false memory will be greatly attenuated in early childhood, an important example being the Deese/Roediger/McDermott (DRM) illusion. Three developmental studies of this illusion (N=282) found that (1) it was at near,floor levels in young children, (2) it was still below adult levels by early adolescence, and (3) the low levels of the illusion in young children may be due to failure to "get the gist" of DRM materials. [source] Neuronal activity and neurotrophic factors regulate GAD-65/67 mRNA and protein expression in organotypic cultures of rat visual cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2003Silke Patz Abstract Environmental factors are known to regulate the molecular differentiation of neocortical interneurons. Their class-defining transmitter synthetic enzymes are the glutamic acid decarboxylases (GAD); yet, fairly little is known about the developmental regulation of transcription and translation of the GAD-65/67 isoforms. We have characterized the role of neuronal activity, neurotrophins and afferent systems for GAD-65/67 expression in visual cortex in organotypic cultures (OTC) compared with in vivo in order to identify cortex-intrinsic regulatory mechanisms. Spontaneously active OTC prepared at postnatal day 0 displayed from 10 days in vitro (DIV) onwards 12,14% GAD-65/GAD-67 neurons similar to in vivo. However, GAD-65 mRNA was higher, whereas GAD-67 protein was lower, than in vivo. During the first week neurotrophins increased whereas the Trk receptor inhibitor K252a and MEK inhibitors decreased both GAD mRNAs and proteins. After 10 DIV GAD expression no longer depended on neurotrophin signalling. Activity-deprived OTC revealed only 6% GAD-67 neurons and mRNA and protein were reduced by 50%. GAD-65 mRNA was less reduced, but protein was reduced by half, suggesting translational regulation. Upon recovery of activity GAD mRNAs, cell numbers, and both proteins quickly returned to normal and these ,adult' levels were resistant to late-onset deprivation. In 20 DIV activity-deprived OTC, only neurotrophin 4 increased GAD-65/67 mRNAs, rescued the percentage of GAD-67 neurons and increased both proteins in a TrkB-dependent manner. Activity deprivation had thus shifted the period of neurotrophin sensitivity to older ages. The results suggested neuronal activity as a major regulator differentially affecting transcription and translation of the GAD isoforms. The early presence of neuronal activity promoted the GAD expression in OTC to a neurotrophin-independent state suggesting that neurotrophins play a context-dependent role. [source] | ||||||||||||||||