<p> Cellular DNA is condensed and stored with the help of proteins, especially histones. This mix of DNA and proteins is termed chromatin. Manipulations of chromatin include post-translational modifications (PTMs) of histone proteins, such as the addition of methyl or acetyl groups, and the movement of histones by chromatin remodeling complexes to control how tightly or which regions of DNA are condensed or exposed. These actions can impact gene expression and thus influence the differentiation of tissues during development. I investigated if the enzyme protein arginine methyltransferase 5 (PRMT5), which mono- or symmetrically dimethylates arginine, is acting on histones during early development in Xenopus laevis. I also investigated if Williams syndrome transcription factor (WSTF) occurs within chromatin remodeling complexes during early development in X. laevis. WSTF interacts with the protein ISWI in early embryos, indicating it is part of a chromatin remodeling complex during this period of development. </p>

<p> To maintain human health, the lymphatic system requires a structurally and functionally sound network of lymph vessels to absorb lipid-based nutrients, preserve extracellular fluid homeostasis, and mediate immune responses. Aside from lymphedema, investigations in the past few decades have found that impairment of the lymphatic vasculature is also involved in processes such as inflammation, tumor metastasis, fat metabolism, and obesity. However, despite a long history of study and rekindled vigor in the field of lymphatic vascular research, our knowledge of lymph vessel development and physiology is still quite limited. Recently, mutations in a protein family known as connexins (Cxs) were identified as the cause of lymphatic dysfunction in some cases of inherited lymphedema. This dissertation explores the role of primarily two specific connexins, Cx37 and Cx43, and the transcription factor Foxc2 in the morphogenesis and function of the lymphatic vasculature in mice. To accomplish this, phenotypic characterization of mice with genetic deficiencies (knockout mice) in Cx37, Cx43, and/or Foxc2 was performed principally via necropsy, histological techniques (immuno-fluorescence microscopy and H&amp;E staining), and Evans blue dye (EBD) injections. Developmental abnormalities were found in lymphatic vascular growth, patterning, and remodeling in mice lacking Cx37, Cx43, Foxc2 or a combined deficiency of these proteins. Reductions or complete loss of lymphatic valves were a common finding in mice lacking one or more of these proteins. These valve deficits underlay lymphatic insufficiencies that resulted in lymphedema and chylothorax in some genotypes. Foxc2 was found to be a regulator of Cx37 expression. Moreover, Foxc2 was also dependent on Cx37 function for proper morphogenesis of lymph vessels. These findings pertaining to the expression of connexins in the lymphatic vasculature, their role in lymphatic valvulogenesis, and the interdependence of Cx37 and Foxc2 during lymph-vascular development represent my original contributions to human knowledge.</p>

In aging Brown Norway rats, there is an activation of the immune system represented by a striking increase in the number of halo cells. As the blood-epididymis barrier should protect from immunological attack, we hypothesized that there would be changes in the structure and function of this barrier with age. Immunocytochemical localization of occludin, ZO-1 and E-cadherin, as well as lanthanum nitrate permeability of the blood-epididymis barrier, were done using the epididymides of rats aged 3, 18, and 24 months. Occludin, ZO-1, and E-cadherin immunostaining was observed at the apico-lateral junction between principal cells in the initial segment of 3-month-old animals; with increasing age, occludin and ZO-1 reactivity decreased, while E-cadherin staining increased along the lateral membrane between principal cells. The most dramatic changes were seen in the corpus epididymidis with age; the intense E-cadherin cytoplasmic staining that was observed at 3 months was absent by 24 months and no occludin or ZO-1 reactivity was observed in older animals. (Abstract shortened by UMI.)

To evaluate why discordance may occur between regression coefficients from cross sectional and longitudinal analyses when ventilatory function is related to ageing, a population was created by computer, and modelled to simulate functional change during life. The program incorporated the effects of many factors known to influence lung function measurements, which were adjusted experimentally so that their contributions to any discordance could be assessed. Regression analyses showed that significant discordance could be induced if the oldest birth cohort failed to reach the same maximal level of function as the youngest; if a quadratic ageing term was excluded from the independent regression variables; or if the effects of certain confounders were present. Discordance occurred additionally if cross sectional estimates became imprecise, but then the differences (often marked) from longitudinal estimates were not significant. It is concluded that discordance may be fundamental and unavoidable (though explicable), or merely a consequence of imprecision.

We studied the consequences of providing rat dams with elevated levels of dietary fat during lactation on stress responses in the offspring at different stages of development. High-fat feeding increased total milk lipid levels, and led to increased lipid deposition and plasma leptin levels in pups. Ten-day-old neonates from high-fat fed mothers had reduced stress responsiveness compared to controls. In contrast, 35-day-old pups from mothers fed high-fat diets showed greater stress-induced ACTH secretion. These findings indicate that maternal diet has effects on hypothalamic-pituitary-adrenal (HPA) responsiveness, which can persist after weaning to a normal rat chow diet. We also investigated macronutrient selection in the offspring, since differences in nutrient preferences may produce long-lasting consequences of lactational diet. However, our results did not support an involvement of maternal diet in postweaning nutrient selection. Furthermore, HPA stress responses were no longer related to maternal diet once offspring reached maturity.

The purpose of this study was to evaluate the effects of a high intensity strengthening program on both muscle function and mobility in an elderly, institutionalized population. Thirty male subjects were randomly assigned to a training group three times per week or to a control "attention" group. Dynamic and isometric strength of the quadriceps, shoulder extensors and elbow flexors were measured by the one repetition maximum (1RM) and a hand-held dynamometer (Nicholas Manual Muscle Tester), respectively. Mobility skills were evaluated with the timed "Up & Go" (TUG) test and by an average walking speed over 30 m. Following the 12 week intervention, post-training evaluations demonstrated significant differences between groups with improved 1RM of both quadriceps (47%), isometric strength of the right shoulder extensors (15%), TUG scores (39%) and average walking speeds (17%). In conclusion, high intensity strength training was found to be not only feasible in the reversal of muscle weakness but also as an effective strategy in attenuating the potential loss of mobility often observed in an elderly, institutionalized population.

In a previous prospective study from our laboratory, the prognostic significance of the auditory brainstem evoked response (ABR) was assessed in high risk neonates. An abnormal ABR predicted neurologic sequelae at 1 year; however there were false negatives. In this study, somatosensory evoked responses (SER) were performed together with the ABR so that a wider distribution of the nervous system could be evaluated. Testing was carried out on healthy and high risk neonates in the newborn period and in infancy. Infants were subsequently evaluated in a blind fashion at 1 year of age by a pediatric neurologist and psychologist. As part of this study, normative data and reliable testing procedures needed to be established. The effect of gestational age on evoked responses performed in the newborn period was also determined. / The results demonstrated that the ABR and SER can be reliably recorded in newborns. Latency and morphological changes on serial testing reflected maturation of the nervous system. Chi square analysis revealed that an abnormal SER or ABR predicted neuromotor impairment at 1 year of age. The type of SER abnormality further delineated the degree of disability. A normal SER and ABR predicted normal neurodevelopmental outcome. In conclusion, multi-modality evoked response testing yielded valuable prognostic information for the newborn at high risk for neurologic sequelae.

Alpha-fetoprotein (AFP) is a tumor-associated embryonic serum glycoprotein, existing in the circulation as a heterogeneous population of closely related molecular variants. The biological function(s) of AFP is not known, but the precisely regulated expression of AFP molecules during ontogenetic development and in certain diseases is consistent with an immunoregulatory function. / The present thesis examines the functional significance of murine AFP microheterogeneity. In the initial phase of this study, seven individual AFP isoforms were purified with a novel separation protocol developed on Mono Q anion-exchange columns linked to an FPLC system. All seven subspecies were further characterized by isoelectric focusing gels, immunoblot analysis, molecular weight determination, and sialic acid composition studies. When all seven variants were tested in several AFP sensitive immune assays, we determined that all the immunosuppressive activity of native AFP was localized to a single distinct molecular variant. This isoform, AFP-1, exhibited an isoelectric point of pH = 5.1, contained 1 mol of sialic acid/mol of protein, and represented approximately 6% of the total population of naturally occurring AFP isoforms isolated from the amniotic fluid at days 15-19 of murine gestation. Further studies indicated that sialic acid expression on the carbohydrate portion of the AFP molecules was unlikely to be involved in the suppressor function. / Since it has been reported that the polyunsaturated fatty acids arachidonic acid and docosahexaenoic acid complexed to AFP molecules may be necessary for the expression of AFP-mediated immunoregulatory activity, we also examined the potential contribution of these polyunsaturated fatty acids to the immunoregulative function of the active isoform. Gas liquid chromatographic analyses, delipidation procedures and fatty acid reassociation experiments indicated that these fatty acids are unlikely to contribute to AFP-mediated immunosuppressive activity. We also determined that MAF-derived AFP from different gestational time points including days 10.5, 12.5, 14.5, 16.5, and 18.5 exhibits immunosuppressive activity in vitro. All the above results are the first direct demonstration that individual molecular variants of murine AFP have distinct immunoregulatory properties. This should facilitate a better comprehension of the relationship of molecular structure to biological function of AFP molecules during fetal development.

Thesis (Ph.D.)--Pacific Graduate School of Psychology, 1994. / Source: Dissertation Abstracts International, Volume: 56-06, Section: B, page: 3446.

Thesis (Ph.D.)--Indiana University, Dept. of Psychological and Brain Sciences and the Program in Neuroscience, 2009. / Title from PDF t.p. (viewed on Jul 20, 2010). Source: Dissertation Abstracts International, Volume: 70-12, Section: B, page: 7839. Advisers: Dale R. Sengelaub; Gregory E. Demas.