No description available.

Germinal centres are dynamic structures in which a number of kinetic processes take place. This thesis was designed to investigate mechanisms whereby one of these kinetic events, germinal centre cell proliferation, is regulated <I>in vivo</I>. In order to achieve this, the proliferative rate of germinal centre cells was measured in C3H/HeN mice under a variety of experimental conditions. In particular, the effect on germinal centre cell proliferation of different classes of antigen and of variously timed doses of the immunosuppressant drug cyclosporin A, was examined. In some experiments, an immunohistochemical technique was employed to demonstrate the distribution of antigen within murine spleens and to correlate the presence of antigen within germinal centres with the germinal centre cell birth rate. The results showed that the type of antigen to which an animal is exposed does determine the subsequent rate of germinal centre cell proliferation. In addition it became apparent that specific regulatory mechanisms were at work within murine germinal centres which either stimulated or inhibited germinal centre cell proliferation depending on the stage of the germinal centre reaction. The proliferative response to antigen was also significantly affected by treatment of the animals with cyclosporin A. The effect of the drug varied depending on the timing of its administration in relation to antigen. These results indicated that T cell derived cytokines play a central role in regulating both stimulation and inhibition of germinal centre cell proliferation. It is proposed that interleukin-4 and interleukin-5 are involved in driving the former, while interferon-γ is a candidate for mediating the latter.

Zugl.: Lübeck, Univ., Habil.-Schr., 2003 / Titel vom Label

Habilitationsschrift--Cologne, 1978. / Summary also in English, French and Russian. Includes bibliographical references (p. 351-358) and index.

Thesis--Universidad Nacional Autónoma de México.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. Description based on print version record.

No description available.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.

Cette thèse aborde certaines caractéristiques des politiques de régulation et de la concurrence dans le secteur des Technologies de l'Information et de la Communication (TIC). Plusieurs problématiques de régulation ex-ante sont abordées, traitant de l'investissement dans les infrastructures de réseaux fixes de télécommunications et de la mise en place de tests de ciseaux tarifaires par les autorités de régulation du secteur des télécommunications en Europe. Sont également étudiées différentes problématiques de politique de la concurrence, comme l'impact de la vente liée de produits créant des coûts de changement pour les utilisateurs ou la prise en compte des terminaux d'accès pour l'analyse du marché du livre électronique en droit de la concurrence. Les impacts de la régulation sectorielle sur la politique de la concurrence sont également analysés, avec une application à la définition et la gestion par les autorités de concurrence de la pratique de ciseau tarifaire dans les industries de réseaux. Enfin, cette thèse met en perspective différents avantages et inconvénients des interventions ex-ante et ex-post, respectivement par les autorités de régulation sectorielle et de concurrence. / This thesis approaches several distinctive features of regulation and competition policy in the Information and Communications Technology (ICT) sector. It tackles some issues in ex-ante regulation on investment in new fixed telecommunications network infrastructures, and the application of margin squeeze tests by European regulatory authorities in the telecommunications industry. It also analyzes issues related to ex-post competition policy, such as the impact of bundling products with switching costs, or the competition authorities' investigations in the electronic book market. Further analysis on the impact of ex-ante regulation on ex-post competition policy is provided, in particular via studies on the definition of a margin squeeze conduct in network industries, and how competition authorities deal with it. Finally, this thesis evaluates several advantages and weaknesses of both ex-ante regulatory authorities' and ex-post competition authorities' interventions.

No description available.