There is evidence that amyloid deposition within the brain is of major importance in the pathogenesis of Alzheimer's disease (AD), but the mechanism of this deposition is not known, and several theories are currently under great debate. The present study of intraneuronal changes in the human brain with age and disease suggests a new explanation for amyloid plaque formation in the pathogenesis of AD. / This work indicates that intraneuronal inclusions originally observed by Rees (1975), may contain amyloid peptide (Abeta), the beta-pleated form of which is the major component of the amyloid plaques in AD. We have therefore called them amylosomes. Using the techniques of histology, immunohistochemistry, computerized morphology, as well as protein isolation and analysis, we examined the distribution, size, density and chemical composition of amylosomes in the human brain throughout life. Amylosomes appear during early childhood and remain constant in size and number until advanced old age. Their protein content and immunostaining characteristics indicate they contain Abeta, and their dendritic location in regions where AD plaques form suggested a possible role in Abeta transport from the brain to the CSF. We therefore isolated and quantified human brain microtubule proteins (MT) and the dendritic microtubule-associated protein 2 (MAP2), assessed their ability to polymerize in vitro, quantified the MAP2 mRNA with age, and related these results to the apolipoprotein E (APOE) genotype, which is known to modulate the risk of AD. There was an age-related decrease in MT proteins and MAP2 and in their ability to polymerize, that was accelerated in individuals with APOE epsilon4 allele(s), the group at greatest risk of AD. These results are consistent with the proposal that amylosomes play a role in Abeta metabolism, and an age-related decrease in the dendritic MT transport system could lead to retention of amylosomes, within the brain, with deposition of the Abeta and plaque formation as a consequence. This theory can account for most of the important features of AD, and resolves a number of contradictory hypotheses, as well as suggesting relevant area for further investigation. A better understanding of the pathogenesis will hopefully reveal strategies for prevention and treatment of this common and presently incurable disease.

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There are increasing numbers of preterm children of very low and extremely low birth weights surviving due to advances in neonatal care. The majority of these children attend mainstream classrooms and perform in the low average range on cognitive measures compared to peers. However, outcome studies document a range of subtle, clinically important impairments in their motor, visual-motor and visual perceptual performance compared to peers. The impact of these impairments on a complex, occupational task such as handwriting performance has never been investigated in the preterm population using an objective measure, except through parent or teacher questionnaires. / The primary objective of this doctoral thesis was to characterize and compare handwriting performance in preterm children (birth weight of ≤1250 grams) attending Grade One, to typically developing peers matched by age, gender and classroom. Standardized outcome measures were used to examine handwriting performance, sensorimotor component skills and psychosocial factors. Preterm survivors demonstrated significantly lower handwriting legibility and slower speed scores compared to matched peers. Visual perception and motor accuracy were identified as predictors of legibility; and in-hand manipulation (translation) and finger identification were associated with handwriting speed in preterm children. However, in typically developing children, legibility was associated with upper extremity steadiness, visual motor control and in-hand manipulation (rotation); and speed was associated with in-hand manipulation (translation) and upper limb speed and dexterity. These findings have important implications for clinical practice in guiding both evaluation approaches and intervention strategies. Clearly, preterm survivors are at high risk for developing handwriting difficulties at school-age. Increasing awareness may help with early identification and intervention with a view towards minimizing the negative effects on self-esteem and academic achievement often documented in children with handwriting difficulty.

<p> Activating mutations in fibroblast growth factor receptors (FGFR) -1, -2, -3 cause craniosynostosis, the premature fusion of one or more cranial sutures, in Apert, Crouzon, Pfeiffer, Muenke, and Beare-Stevenson cutis gyrata syndromes. These conditions are also characterized by other skeletal anomalies and variable effects on brain development and function. The variability of central nervous system defects and the occurrence of severe cognitive impairment despite early surgical intervention, particularly in Apert syndrome, led us to hypothesize that the activating FGFR mutations have a direct, adverse effect on brain development. In this study we looked for aberrations in diverse cellular processes affected by Fgf signaling in the developing telencephalon of an Fgfr2+/S252W Apert mouse model to uncover the mechanisms by which these defects occur. We present evidence that in the Apert mouse model, the radial glial cells to intermediate progenitor transition is depressed during mid-to-late neurogenesis. We also observed a significant increase in apoptosis in the anterior forebrain in Apert newborns. Lastly, an increase in the migration of astrocytes to the dorsolateral cortex by post-natal day five was observed. These results suggest that important physiological roles of Fgfr2 signaling in the development of the cerebral cortex are adversely affected by syndromic activating mutations of Fgfr2, which may lead to gross brain abnormalities. </p>

The prevalence of abnormal pregnancy outcomes in the offspring of 103 epileptic women followed prospectively during pregnancy between 1982 and 1989 was compared with that in the previous study of 119 pregnancies by Dansky et al. from the same institution. / Our results have shown a significant decrease in the prevalence of major malformations, as compared with the previous study: 8.8% vs. 24.1% (P $<$ 0.01). Monotherapy was more frequent and the mean number of drugs used during pregnancy was significantly smaller in the present study. Phenytoin, phenobarbital and primidone were prescribed less frequently in the present study, whereas carbamazepine and valproic acid were used more frequently. Plasma levels of valproic acid during pregnancy were higher in mothers of malformed babies. In the present study, plasma folate levels were significantly higher, and more patients were taking folate supplements during pregnancy. / In conclusion, the type and number of drugs used during pregnancy, as well as the plasma concentrations and serum folate levels, may determine the frequency of abnormal outcomes.

Alzheimer's dementia (AD) is a degenerative neurological disorder involving predominantly the central cholinergic neurons but also other neurotransmitter systems. Over the last decade, several investigators have reported the presence of AD-related peripheral manifestations many of which involving cholinergic and adrenergic markers in non-neuronal tissues such as platelets, fibroblasts, lymphocytes and others. However, since these are unrelated to structures innervated by the peripheral nervous system, it is difficult to comment on their possible pathological as well as functional implications in the process of the disease. / The aim of the present study was to evaluate possible AD-related dysfunctions in peripheral tissues known to be innervated by anatomical structures located outside the CNS. Cholinergic as well as adrenergic receptors density and affinity were evaluated in pial vessels obtained post-mortem from 8 confirmed cases of AD and 8 elderly non-demented controls. In addition, direct and axonal reflex sweating responses elicited by local iontophoretic application of acetylcholine were evaluated in 30 probable AD patients, 30 elderly and 30 young controls. / There was a significant (p $<$ 0.05) 43% reduction in total muscarinic binding sites in AD pial vessels as compared to control vessels. When the binding assays were performed in the presence of 75 nM pirenzepine (in order to block muscarinic binding sites with high affinity to pirenzepine), there was still a significant (p $<$ 0.05) 40% diminution in the labelled sites compared to control vessels. The population of $ alpha$1-adenergic binding sites was also significantly reduced (35%: p $<$ 0.05) in AD vessels. In all cases, affinity of the cerebrovascular receptors was comparable in AD and control vessels. On the other hand, ChAT activity (used as an index of cerebrovascular cholinergic innervation) determined in human pial vessels showed a non-significant 25% reduction in AD compared to control pial membranes. Similarly, $ beta$-adrenergic binding site density was unaltered in AD vessels. Functional evaluation of the sweating response in AD patients and related controls showed that the nicotinic receptor mediated axonal reflex sweating response was significantly reduced in AD patients as compared to young controls and elderly controls (44% and 40% respectively, p $<$ 0.05). In contrast, the slight diminution observed in direct sweat response (mediated by muscarinic receptors) between AD patients, elderly and young controls was not statistically significant. / In view of the reported distribution of muscarinic and adrenergic receptors in the pial vessel wall, the reduction in total and subtype specific muscarinic binding sites as well as the drop in $ alpha$1-adrenoceptors may argue in favour of a degenerative process at the level of the blood vessel wall itself. Such conclusions would agree with the relatively preserved cholinergic innervation suggesting spared cerebrovascular innervation. In contrast, the significant reduction in axonal reflex sweat response observed in AD, is strongly suggestive of a peripheral degenerative process involving post-ganglionic sympathetic neurons to sweat glands. / The detected changes are suggestive of a further decrement of autonomic control in AD different from what have been observed in normal aging. These changes may contribute to the deterioration of the brain perfusion and autonomic functions regulation in AD.

Extensive in vitro and in vivo studies indicate that one important biological function of the embryo-specific glycoprotein alpha-fetoprotein (AFP) is to down regulate certain T cell responses in order to control potentially harmful autoreactive events during fetal development. However, there are some reports which contend that AFP-mediated immunosuppression is not an inherent property of the molecule itself, but is instead, hypothesized to be either a function of a low molecular weight inhibitor bound to AFP or to a post-translational modification of the protein. / To resolve these issues, the present thesis examines the possible contributory roles of endogenous and exogenous ligands, including TGF-beta2, and post-translational modifications in AFP-mediated immunoregulation. We were able to abundantly express rAFP's in bacterial, baculovirus and yeast expression systems. / The next series of studies that were performed examined the contribution of post-synthetic biochemical modifications to AFP-mediated immunosuppression. The results of these studies establish that both rAFP's are functionally equivalent to one another, as well as to natural fetal derived AFP. / These results prompted an in-depth investigation into the identification of the immunoregulatory active site(s) within the AFP molecule. Having established that putative ligands as well as post-translational modifications do not impart immunomodulatory activity to AFP, cDNA's encoding mouse AFP domains were generated by PCR and produced in a yeast expression system. / An equally important, yet not extensively studied biological activity of AFP, is its hematopoietic growth factor property. We show that there is an increased number of viable bone marrow (BM) cells cultured in AFP versus albumin supplemented cultures or media alone. Furthermore, the data suggest that AFP may be retarding the progression of programmed cell death of hematopoietic cells in serum free cultures. (Abstract shortened by UMI.)

Voltage-gated potassium currents make important contributions to neuronal function. Postsynaptically, potassium currents regulate excitability to depolarizing inputs and determine action potential firing frequency. Furthermore, voltage-gated potassium channels are known to affect the shape of the presynaptic action potential, so as to influence calcium influx and neurotransmitter release. I have focused on the expression of voltage-gated potassium channel genes by peripheral neurons. Among my objectives were to determine which voltage-gated potassium channel genes are expressed by sympathetic neurons of the superior cervical ganglia (SCG) and measure mRNA levels for these genes during normal neonatal development and during development in culture. I found that P7 SCG neurons expressed low levels of Kv1.4, Kv2.2 and Kv3.1 mRNAs, moderate levels of Kv2.1 and Kv3.3 mRNAs, and high levels of Kv3.4 and Kv4.2. Where the expression level of Kv1.4, Kv2.1, Kv2.2, Kv3.1 and Kv3.3 mRNAs did not change significantly, neither during development in vivo nor in vitro, both Kv3.4 and Kv4.2 mRNA levels underwent significant developmental changes. I found that Kv3.4 mRNA levels increased sixfold during neonatal development, and remained expressed at high levels or increased during culture. In contrast Kv4.2 mRNA levels increased thirty-fivefold during neonatal development, but in culture Kv4.2 mRNA levels decreased to low or very low levels. Additionally, culturing SCG neurons in the presence of the cytokine ciliary neurotrophic factor (CNTF) failed to influence the in vitro developmental mRNA levels of Kv1.4, Kv2.1, Kv2.2, Kv3.1, Kv3.3 nor Kv4.2. Only the expression level of Kv3.4 was significantly increased by CNTF. I also measured the mRNA levels for Kv1.4, Kv2.1, Kv2.2, Kv3.1, Kv3.2, Kv3.3, Kv3.4 and Kv4.2 in sensory neurons of the nodose and trigeminal ganglia. I found that Kv2.1, Kv3.1, Kv3.3 were expressed at similar levels to SCG neurons, Kv3.2 mRNA was detectable, Kv1.4 an / Kv4.2 and Kv1.4 likely contribute to the SCG rapidly inactivating transient current (IAf). Furthermore, changes in Kv4.2 mRNA levels may account for the developmental changes in IAf density in vivo and in vitro. Kv2.1, Kv2.2, Kv3.1, Kv3.3 and Kv3.4 channels likely contribute to the SCG slowly inactivating transient current (IAs), perhaps as heteromeric channels. Changes in mRNA levels do not account for developmental changes in IAs current density. Moreover, the increase in Kv3.4 mRNA levels in SCG neurons cultured with CNTF does not account for the sustained expression of lAf and Us. Similar to SCG neurons, Kv1.4 and Kv4.2 likely contribute to IAf on nodose and trigeminal neurons, whereas, Kv2.1, Kv2.2, Kv3.1, Kv3.2, Kv3.3 and Kv3.4 likely contribute to nodose and trigeminal IAs.

Objective. To identify predictors of catch-up growth during the first year of life among small for gestational age (SGA) infants in a developing country setting. / Design. Cohort study, with follow-up visits at 1, 3, 6 and 12 months. / Setting. Pelotas, a southern Brazilian city. / Population. SGA infants who were born in 1993 and whose families lived in the urban area of Pelotas. / Main outcomes. Weight and length gain from birth to 6 months and from 6 to 12 months. / Results. Two hundred twenty term SGA infants were targeted for follow-up, which was achieved for 205 (93.2%) infants at 12 months. At 6 months, the proportion of infants with weight-for-age and length-for-age z-scores <-1.28 SDS was 18.9% and 37.8%, respectively. At 12 months, the proportion of children with a weight-for-age z-score <-1.28 SDS increased to 35.2%, whereas for length-for-age this proportion remained about the same as it had been at 6 months. Severity of intrauterine growth retardation, body proportionality at birth, maternal remunerated work after delivery, maternal age, parity, maternal prepregnancy body mass index and maternal smoking during pregnancy had no significant effect on postnatal growth in the first year of life. Those infants who were weaned by 1 month had faster weight and length gain by 6 months. Socioeconomic status (SES) modified the effect of breast feeding duration on weight and length gain in the first 6 months of life. Among high-SES families, those children who were weaned by 1 month gained 578 g more than those still breast feeding at 6 months. Among low-SES families, however, those children who were weaned by 1 month gained 349 g less than those still breast feeding at 6 months. Those children who were weaned by 6 months had faster weight gain from 6 to 12 months, and this association was not modified by SES, while low SES was associated with slower weight and length gain in the same period. Children of short (<150 cm) mothers gained 1.31 cm less (95% confidence interval -2.52 to -0.1) by 6 months than those of mothers >160 cm. Children who were hospitalized showed a nonsignificantly slower length gain throughout the first year of life. / Conclusion. SGA infants experienced catch-up growth for weight and length but remained shorter and lighter than those in the NCHS reference population at both 6 and 12 months of age. Socioeconomic status and infant feeding were the main determinants of catch-up growth.

The aim of this study was to develop norms for the Movement Assessment of Infants (MAI) and to investigate the concurrent validity of this measure. Sixty-three full-term, low-risk, four-month-old infants were tested according to the MAI, the Bayley Motor Scale and the Wolanski Motor Development Scale. Infants were scored according to the four-month Risk Profile (RP) of the MAI and the Study Population Profile (SPP) which was developed from the behaviours of the infants on the MAI. Risk scores of the infants on the RP were significantly higher than risk scores on the SPP. This difference was attributed to the inability of the MAI to differentiate the variability of normal motor behaviour at four months of age from motor behaviour which is truly deviant from the norm.