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Instructive signals, whether external or internal, play critical roles in regulating the developmental potency or ability to self-renew of stem cells. External signals may range from secreted growth factors to extracellular matrix proteins found in the stem cell niche. Internal signals include activated signalling cascades and the eventual transcriptional mechanisms they initiate. In either fashion, stem cells are regulated in a complex temporal and context specific manner in order to maintain or maximise their unique characteristics. Previous experiments suggest that Wnt3a plays a role in maintaining the pluripotent state of mouse embryonic stem (mES) cells. However, in the absence of leukemia inhibitory factor (LIF), Wnt signalling is unable to maintain ES cells in the undifferentiated state. This implies that maintaining the pluripotent state of mES cells is not the primary function of canonical Wnt signalling. To further characterize the role of Wnt3a in pluripotency and lineage specification undifferentiated and differentiated mES cells were induced with Wnt3a. Wnt3a induced the formation of a metastable primitive endoderm state and upon subsequent differentiation, the induction of large quantities of visceral endoderm. Furthermore, we determined that the ability of Wnt3a to induce a metastable primitive endoderm state was mediated by the T-box transcription factor Tbx3. Our data demonstrates a novel role for Wnt3a in promoting the interconversion of undifferentiated mES cells into a pluripotent primitive endoderm state. Aging of skeletal muscle tissue is accompanied by fibrosis, atrophy and remodeling all of which negatively affect muscle performance. Whether this reduction in skeletal muscle competency is directly attributed to a resident adult stem cell population called satellite cells remains largely unknown. Here, we undertook an investigation into how age affects the transcriptional profile of satellite cells and their repopulating ability following transplantation. We determined that as satellite cells age, both their regenerative capacity and ability to colonize the satellite cell niche is reduced. Additionally, we identified satellite cell specific transcriptional profiles that differed with respect to age. Therefore, we conclude that intrinsic factors are an important determinant of satellite cell regenerative capacity during the aging process.

The aim of this study is to demonstrate the idea of Exoticism and its effect on nineteenth century architectural tendencies and especially on the philosophy and the works of Louis Sullivan (1856-1924). The study begins with an elucidation of the concept &ldquo / exoticism.&rdquo / After the thoughts of a group of nineteenth century European intellectuals are discussed, the philosophy of Sullivan is analyzed. Following chapters are dedicated to the works of Sullivan. Exotic world was the source of a stimulating discourse for the nineteenth century intellectuals. American architect Sullivan also found inspiration in it. In the development of his philosophy, Sullivan concentrated on the idea of &ldquo / integrity of man and nature,&rdquo / and he realized that integrity was present in the art of primitive and especially Oriental cultures. His universal formula, &ldquo / form follows function,&rdquo / was based on the idea that the primitive man did not put a barrier between himself and nature / hence every artwork created by him was a process of transformation of natural forms. Sullivan modeled his designs upon nature and in this way attempted to reproduce this creative process. This study interprets Sullivan&rsquo / s philosophy and works and also discusses their likely contribution to the work of the contemporary architect.

Diss. : Theologische Fakultät : Freiburg i. Br. : 1983-84. - Bibliogr. p. 361-397. Index. -

Thesis (Ph. D.)--University of Washington, 1983. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [381]-410).

Proefschrift--Amsterdam. / "Stellingen": iii p. laid in. "Literaturverzeichnis": p. [526]-536.

Thesis (M.A.)--Sydney. / Includes bibliographical references.

Thesis (M.A.)--Sydney. / Includes bibliographical references.

Stuttgart, Univ., Diss., 2005.

Thesis (PH. D)--Yale University, 1925. / Printed in Great Britain. Without thesis note. Bibliography: p. 287-302.