Angelman Syndrome (AS) is a severe neurodevelopmental disorder that affects 1:12000 newborns. It is characterized by mental retardation, delayed major motor and cognitive milestones, seizures, absence of speech and excessive laughter. The majority of AS cases arise from deletions or mutations of UBE3A gene located on the chromosome 15q11-13. UBE3A codes for E3-ubiquitin ligase that target specific proteins for degradation. To date, a wide variety of Ube3a substrates has been identified. The accumulation of Ube3a-dependent proteins and their effect on the multitude of signal transduction pathways are` considered the main cause of the AS pathology. While the majority of research has been directed towards target identifications, the overall role of Ube3a in activity-dependent synaptic plasticity has been greatly overlooked. The present work is designed to fill some of these knowledge gaps. Chapter 2 is focused on the activity-dependent aspect of Ube3a expression following neuronal stimulation in vivo and in vitro. We examined total Ube3a expression followed by KCl depolarization in neuronal primary culture. By utilizing a subcellular fractionation technique, we were able to determine which cellular pools are responsive to the depolarization. Next, a fear conditioning paradigm (FC) was used to activate neurons in the paternal Ube3a-YFP reporter mouse brain. This mouse model allowed us to resolve spatial and temporal alterations of the maternal and the paternal Ube3a in hippocampus and cortex followed by FC. In accordance to KCl depolarization results, we observed alterations in Ube3a protein but at later time points. Furthermore, we investigated if the absence of activity-dependent Ube3a changes has any effect on learning and memory kinase activation. We utilized KCl and FC to determine synaptic activity-induced ERK 1/2 phosphorylation in acute hippocampal slices and in CA1 area of hippocampus of wild type (Ube3a m+/p+) and Ube3a deficient mice (Ube3a m-/p+). We demonstrated that Ube3a loss leads to impaired activity-dependent ERK 1/2 phosphorylation. It has been established that Ube3a m-/p+ mice have a profound deficit in LTP, implying the importance of this ligase in excitatory synaptic transmission. The abnormal LTP could be partially explained by an aberrant CaMKII function, decreased activity-dependent ERK 1/2 phosphorylation and reduced phosphatase activity. These proteins have also been implicated in another form of synaptic plasticity such as long-term depression (LTD). Chapter 3, we investigated the contribution of Ube3a to NMDAR - dependent and - independent LTD. Our data showed that Ube3a m-/p+ P21-30 animals exhibit the impairments in both forms of LTD. Next, we focused on elucidating molecular mechanism underlying the reduced mGluR1/5-LTD. We discovered that mGluR1/5 kinase activation such as ERK, mTOR and p38 is not affected by Ube3a loss. In concordance with previous work, we detected increased Arc expression together with abnormal AMPAR distribution in the Ube3a m-/p+ hippocampus. Surprisingly, the mGluR1/5 induced GluR2 trafficking was normal. Our findings infer that elevated Arc levels together with the increased internalization of AMPAR may result in compromised basal state of the synapses leading to a more depression-like state in Ube3a m-/p+ mice. Evidence points that loss of Ube3a produces alterations in a variety of activity-dependent signal transduction cascades that may ultimately result in impaired synaptic plasticity and cognition. Similar to AS, abnormal molecular and behavioral phenotypes have already been observed in other mouse models of human mental retardation such as Fragile X Mental Retardation Syndrome (FXS). Chapter 4 is set to explore if any correlation can be found in between these neurodevelopmental disorders. Analysis of crude synaptoneurosomes of adult Fmr1 KO mice revealed a significant reduction in Ube3a protein. Additionally, a blunted translation of Ube3a in response to mGluR1/5 stimulation was observed. However, we didn't find any evidence of direct interaction between Ube3a mRNA and Fragile X Mental Retardation Protein (FMRP). To examine if some of the pathology seen in Fmr1 KO mice is due to Ube3a downregulation, we performed a rescue experiment by increasing overall levels of Ube3a in hippocampus of FRMP deficient mice. An exhaustive battery of behavioral testing indicated that alterations of Ube3a expression impacted only associative fear conditioning. In summary, the present work has attempted to answer some of the fundamental questions about Ube3a and its role in synaptic plasticity. We have demonstrated that Ube3a expression is modulated by synaptic activation and its activity-dependent alterations are essential for normal brain functioning. Additionally, our data suggest that Ube3a is not only significant for the synaptic excitation but also crucial for the synaptic depression. Finally, our findings indicate that the alteration of Ube3a expression may contribute to the cognitive phenotypes in other neurodevelopmental disorders such as FXS suggesting an advantage of exploring Ube3a function outside the AS research.

This is a report of a descriptive study in which a random sample of fifty out of four hundred returned questionnaires from parents with a mentally retarded child were analyzed. The foci of analysis were: (1) parental attitudes toward the child; (2) the changes experienced by the family as affected by birth order and sex of the mentally retarded child; (3) how the diagnosis was accomplished; and (4) how in their opinion services during this diagnostic period could be improved. The data revealed that: (1) protectiveness toward the child is the predominant parental response; (2) negative changes are probably twice as high with an only child who is retarded; (3) male retardates are somewhat more disruptive than are female; (4) diagnosis must be individualized; however, generalizations which can be made include: understandable language, patience, empathy, and above all honesty.

Fetal growth restriction (FGR) is a common and potentially life-threatening complication that affects 5-10% of human pregnancies. Maternal genetic predisposition and fetal male sex are known risk factors, but the underlying mechanisms are unknown. To study a known maternal genetic risk factor and the impact of fetal sex, we employed a published transgenic (TG) mouse model, which was designed to mimic a common human angiotensinogen (AGT) promoter variant associated with a 20% increase in circulating AGT levels. We hypothesized that TG dams would deliver growth restricted pups and that the underlying mechanism would be related to differences in maternal uterine pregnancy-induced vascular remodeling, abnormal blood flow to the placenta, and placental damage. In addition, since growth restricted human males are at an increased risk of developing adult onset hypertension, which has been associated with reduced nephron development, we tested for developmental programming in our mouse model and the impact of fetal sex. Our results show that TG dams have reduced uterine and placental angiogenesis when their pups were males, but relatively normal angiogenesis in the female siblings compared with wild-type controls. The uterine placental bed in TG dams had abnormal pro-angiogenic/anti-angiogenic expression ratios that were related to differences in uterine natural killer cell activation and fetal sex. The abnormal phenotype could be rescued by delivering vascular endothelial growth factor (VEGF) to uterine endothelial cells. Male progeny from TG dams had abnormal kidney epigenetic changes, fewer nephrons as adults, and they developed stress-induced hypertension. We conclude that the combination of maternal genetic risk and fetal male sex affect uteroplacental angiogenesis leading to FGR and the programming of stress-induced hypertension.

The purposes of this study were: (1) to compare nine groups of subjects composed of intellectually normal children, mentally retarded adolescents, and mentally retarded adults on a three dimensional concept formation task; (2) to determine the effects of discrimination training on the sortings of the nine groups on the experimental task. The 207 subjects of this study were divided into nine groups. Seven of t he groups, consisting of high average and low average grade 3, superior high average, and low average grade 6, and high and low adolescent retardates were chosen on the bases of school grade level (3, 6, and adolescent retarded) and IQ level (low average, high average, superior, low and high adolescent, and low and high adult retarded) with each group composed of 21 subjects, except the two adolescent groups which were composed of 30 subjects each. The remaining two groups, high and low adult retardates, were chosen on the bases of chronological age (between 20-35) and IQ level (high and low mildly retarded), with both groups composed of 30 subjects. One-third of the subjects in each group were given special discrimination training with the task objects. The experimental task required each subject to place 27 objects in three trays which could be moved back and forth. The trays were stacked one on another vertically but separated by one-sixteenth of one inch. Each tray was divided into nine boxes. The objects were of three kinds: sphere, cube, and tetrahedron; three sizes: 1, 1 1/2, and 1 3/4 inches; and three shades of blue: dark, medium, and light. Each subject was directed to place the objects in the three dimensional matrix as he desired. The discrimination subjects of each group performed the same task, but they received special orientation training with the trays and objects. One task object, a medium sized, medium blue cube was pre-placed in the center box of the middle tray for an anchor point for each subject to use for his sortings. The results of this study indicate the following: The nine diverse groups included in this study did not show statistically significant differences in their grouping of identical color shades, identical forms and identical sizes in the three dimensional matrix when each element The nine groups did not significantly (statistically) differ in their use of the left to right direction in their grouping of identical color, identical form, and identical size horizontally as well as vertically. This lack of significance also applied to the use of the front to back direction in sorting color, form and size differences both horizontally and vertically. Discrimination training did not significantly affect the performance of the nine groups on any of the dimensions measured in this study. Adult and adolescent retarded groups showed noticeable effects from discrimination training by increasing their responses to size likenesses in their horizontal sortings. In general, normal subjects increased their groupings of identical elements more than retarded subjects, hut the findings indicate that IQ and chronological age did not significantly (statistically) affect discrimination training in these nine groups. Neither chronological age nor IQ significantly (statistically) affected the subjects' concrete tendency to place the largest size objects into the top tray which was most accessible for sorting.

Abstract not available

In an attempt to find a way of improving the damage tolerance of composite bonded repairs to metallic aircraft structures, the effect of using conventional crack growth retardation techniques in conjunction with bonded repairs was experimentally investigated. Hence, an experimental test program was set up to determine whether fatigue crack growth under bonded repairs is retarded further by giving the crack to be repaired a crack growth retardation treatment prior to repair patch application. In addition, it was set up to determine the influence of a bonded repair on the effectiveness of a crack growth retardation method. Centrally cracked aluminium plates were used. Stop drilling followed by cold hole expansion and the application of single overloads were selected as retardation treatments. Two patch materials were considered; boron/epoxy and Glare 2. Further test variables were the aluminium alloy and the plate thickness. Fatigue testing was carried out under constant amplitude loading and baseline results were determined first. In addition to optically monitoring the crack growth, local and global out-of-plane deformations were visualised with holographic interferometry and shadow moire??. Furthermore, the stress intensity factors under the repair patch were examined with strain gauges and measurement of the central crack opening displacement. Disbonds and fracture surfaces were studied after residual strength tests. The crack growth results obtained showed that retardation treatments decrease crack growth rates under a repair patch and that the effectiveness of a retardation treatment is increased by the patch. Although identical crack growth rates were observed under boron/epoxy and Glare 2 patches, the reinitiation period after the retardation treatment lasted longer when Glare 2 patches were applied. Analytical predictions of the extent of retardation based on existing models showed that the conjunctive effect of retardation treatments and bonded repairs was underestimated. A sustained reduction in crack growth rates was observed under bonded repairs with a prior overload retardation treatment. It was concluded that the damage tolerance of bonded repairs is increased by the application of a crack growth retardation treatment because the crack growth is retarded further. These findings indicate that the range of cracks in aircraft for which bonded repairs can be considered is expanded and that economic benefits can be obtained.

Work, leisure and retirement are fundamental aspects of life for individuals with an intellectual disability, just as with the general population. Many educational efforts have taught knowledge and skills to persons with an intellectual disability to improve their functioning in the work and leisure domains. More recently, retirement concerns have become particularly salient because so many individuals now live much longer. The present study looked at using a conceptual approach to improve education in these three domains. It employed the principles that instruction works much better when it proceeds from an individual=s existing concepts and that instruction should teach useful concepts that an individual can apply to improve his or her real world functioning. This conceptual approach has not been used much with the education of persons with an intellectual disability. In Study 1, sixty adults with an intellectual disability were interviewed to determine their existing concepts of work, leisure and retirement and their work and leisure histories. Most had solid concepts of work and leisure, but with some gaps, particularly in notions of volunteer work and occupational status. Most reported satisfactory work and leisure lives. Most had a relatively poor concept of retirement at best and had done little or no retirement planning. These data suggested some key targets for an educational program to improve their knowledge and functioning in these domains. In Study 2, these data were used to develop an instructional program that focussed on gaps in knowledge of volunteer work, banking, budgeting and participation in satisfying leisure activities and in retirement planning. This instructional program was delivered over eight weeks to a class consisting of nine adults with an intellectual disability, with some success. This general conceptual approach can be usefully applied to teaching in other important domains with persons with an intellectual disability. They can be taught key concepts which they can use to live their lives more purposely and independently.

Intrauterine Growth Restriction (IUGR) is evident in infants born with a reduced weight or length, and/or increased thinness for gestational age. IUGR is associated with altered postnatal growth and regulation, due to unknown mechanisms. Much clinical IUGR results from the reduced delivery of essential substrates (oxygen and nutrients) to the fetus, due to either maternal or placental limitations. Catch-up growth (accelerated rate of growth in absolute or fractional terms) occurs in the majority of IUGR infants, and returns an infant to their predetermined growth curve. IUGR is associated with increased risks of morbidity and mortality in the perinatal period, and with a reduced final adult stature and increased risk of adult onset diseases, particularly diabetes and cardiovascular disease. Catch-up growth after IUGR predicts improved health in terms of reduced hospital visits in infants and children, and an increased final adult stature but also predicts an increased risk of developing obesity, as well as diabetes and cardiovascular disease. The underlying mechanisms for catch-up growth may contribute to this range of outcomes in later life, but are poorly understood. Studies in IUGR infants have demonstrated increased absolute and/or fractional growth rates following birth, termed catch-up growth, in the presence of reduced or normal plasma concentrations of the thyroid hormones and major anabolic hormones (insulin and/or IGF-I). This suggests that increased sensitivity to, rather than increased production of insulin, IGF-I and thyroid hormone, causes catch-up growth following IUGR. We therefore hypothesised that placental restriction of fetal growth would reduce size at birth and increase postnatal growth and adiposity in association with increased metabolic sensitivity to insulin, IGFs and thyroid hormones. This study has shown that the placentally restricted (PR) lamb has a reduced size at birth in terms of soft and skeletal tissues, has increased rates of growth postnatally, and has increased adiposity by six weeks of age. We have also shown that PR of fetal growth in the sheep did not alter gestational age at delivery, but reduced survival rate. PR lambs demonstrated catch-up growth in most parameters by 30 days of age and increased adiposity at six weeks of age compared to the control lambs. Placental restriction increased insulin and IGF sensitivity of circulating free fatty acids, which in turn, predicts increased adiposity. Neonatal catch-up growth after fetal growth restriction was substantially predicted by both abundance of, and metabolic sensitivity to insulin, suggesting increased insulin action as an underlying cause. Catch-up growth occurs in the neonate despite reduced concentrations of fasting plasma IGFs, along with increased IGF sensitivity of free fatty acid metabolism and adiposity. Plasma TH concentrations predicted growth of soft and skeletal tissue in lambs during early postnatal life, particularly in those undergoing catch-up growth following PR. Therefore neonatal catch-up growth after IUGR is associated with increased sensitivity to both insulin and IGFs, particularly of circulating free fatty acids, and appears to occur to the extent allowed by the prevailing abundance of these hormones and of thyroid hormones. If this altered endocrine state persists, increased adiposity and its subsequent amplification may contribute to the development of obesity, and related adverse metabolic and cardiovascular outcomes in adult life. / Thesis (Ph.D.)--School of Molecular and Biomedical Science, 2004.

Low birth weight is associated with an increased risk of impaired glucose tolerance and type 2 diabetes and with signs of increased hypothalamic pituitary adrenal axis activity in later life (1, 2). Low birth usually weight reflects a reduction in fetal growth, which largely depends on an adequate supply of nutrients and oxygen. Variations in supply modify the metabolic and neuroendocrine characteristics of the fetus, which in turn modulate the pattern of functional development as well as growth (3). An adverse fetal environment, evident as low birth weight, is therefore proposed to alter functional development with long term effects for the function and risk of disease in the individual later in life (4, 5). Increased HPAA impairs metabolic homeostasis and could therefore mediate effect of prenatal challenge on later metabolic control (6). It was therefore hypothesised that restriction of fetal growth, increases circulating cortisol and/or alters sensitivity to cortisol, which increases fasting blood glucose, and impairs glucose tolerance in the young adult. Large litter size in the guinea pig is characterised by reduced placental and fetal growth, reduced size at birth and insulin resistance in offspring in later life, providing a suitable model to test this hypothesis. Spontaneous restriction of fetal growth in the guinea pig, evident as small size at birth, was associated with increased salivary cortisol, in both sexes but at different stages of postnatal life. In males, salivary cortisol was increased with small size at birth in early and adult life, but reduced later with ageing. In females however, salivary cortisol was increased in juveniles and in aged adults, possibly reflecting the impact of the oestrus cycle on cortisol production in mature cycling females. Altered activity of the HPGA, which can influence that of the HPAA, has also been reported to be programmed by prenatal restriction. In the guinea pig, salivary testosterone in males increased with age and small size at birth in juveniles, young and aged adults. In females, salivary progesterone increased with age up to 300 days, and decreased with size at birth in the young guinea pig. Although testosterone inhibits HPAA activity, in males, mean salivary cortisol correlated positively with mean salivary testosterone at 100 and 300 days of age. In contrast, progesterone may enhance HPAA activity, and consistent with this, in females, mean salivary progesterone correlated with mean salivary cortisol at 400 days of age. Therefore, salivary testosterone in the male and salivary progesterone in the female guinea pig changes with maturation and has previously reported in this or other species, but small size at birth increases salivary testosterone in males with modest effects in early life in females. This together with the unexpected positive associations of salivary cortisol with testosterone in males, suggests that programming of the HPAA makes little contribution to that of the HPAA as indicated by salivary cortisol. Here we show that low birth weight is associated with increased fasting blood glucose and impaired glucose tolerance in both male and female young adult guinea pigs aged 100 days. Fasting and mean (during IVGTT) plasma cortisol was reduced in low birth weight female adult guinea pigs, and is not vary with size at birth at this age in males. This suggests that circulating cortisol does not contribute to the impaired glycaemia associated with small size at birth in the guinea pig. Glucose tolerance was increasingly impaired in males but not females, as mean plasma cortisol increased. This is consistent with cortisol impairing glycaemia in the guinea pig as in other species, in males at least. To assess the role of cortisol in prentally programmed impairment of glycaemia directly, metyrapone or vehicle containing 24% ethanol was administered to young adult guinea pigs for 3 days. Treatment with the latter impaired fasting blood glucose and glucose tolerance in females and the latter in males compared to a previous IVGTT and this was exacerbated in low birth weight females. Metyrapone prevented this impairment of fasting glycaemia and glucose tolerance in the low birth weight adult female guinea pig and in the male guinea pig regardless of birth weight class. Neither vehicle or metyrapone altered plasma cortisol, before or during a second IVGTT. Limited numbers of animals, particularly females, limited this study however and additional investigation is required. Nevertheless this shows for the first time that inhibition of glucocorticoid synthesis in the guinea pig improves glucose control. Furthermore this suggests that the low birth weight guinea pig may be more sensitive to cortisol, have increased cortisol synthesis or reduced inactivation of cortisol in peripheral tissues, leading to increased local cortisol action. In conclusion, alterations in peripheral HPAA activity in the guinea pig due to restricted fetal growth may contribute to their prenatally programmed development of impaired glucose tolerance as young adults, but the extent of that contribution may vary with age and gender. / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

<p>Chromosomal abnormalities are defined as changes in the chromosome structure and fall in one of two categories. The first category is numerical alterations while the second category consists of structural abnormalities. Structural chromosomal abnormalities do not always interrupt genes in order to cause disease. They can also affect gene expression by separating a gene and its promoter element from distant regulatory elements. We have used characterisation of structural chromosomal abnormalities to identify the genetic bases for several congenital disorders.</p><p>In papers I-III, we have applied molecular characterisation of chromosomal translocations in order to identify candidate genes involved in mental retardation, hypospadias and anal malformation and premature ovarian failure. In paper I, we localised the chromosome X translocation breakpoint in a t(X;15) to be in the immediate proximity of the gene <i>ZDHHC15 </i>in a patient with severe mental retardation. Subsequent experiments revealed loss of <i>ZDHHC15</i> transcription in the patient which suggests this gene to be involved in the aetiology of the patient’s phenotype. In paper II, we show that a balanced translocation between chromosomes 6 and 17 in a patient with urogential malformation disrupts 2 genes, one at each translocation breakpoint. We also identified a fusion-gene as a result of the translocation. Our hypethesis is that the translocation together with its molecular consequences is important for the phenotype in the patient. Similarly, in paper III, we have used molecular characterisation of the breakpoints in a balanced translocation between chromosomes X and 11 in order to localise candidate genes in ovarian function. Our results indicate a number of genes affected by the translocation. In paper IV, we have used array-based comparative genomic hybridisation (array-CGH) in order to investigate a cohort of autistic sib-pairs for submicroscopic chromosomal alterations. We have identified several novel duplications and one novel deletion with strong association with autism.</p>