Diss. (sammanfattning) Umeå : Umeå universitet, 2008. / Härtill 3 uppsatser.

Thesis (Ph.D.) - University of Queensland, 1996. / Includes bibliographical references.

The blood of man is rich in plasminogen, the inactive precursor of plasmin, a protease (Astrup, 1956a); the most characteristic action of plasmin is the digestion of fibrin, i.e. fibrinolysis. Many tissues, including the prostate (Rasmussen and Albrechtsen, 1960a), contain substances which can activate plasminogen, and thus initiate fibrinolysis, and it has been assumed that both the excessive fibrinolysis seen in the blood of some patients with prostatic disease (Tagnon, Whitmore, Schulman and Kravitz, 1953a), and in prostatic surgery (Lombardo, 1957), is due to the release of this activator into the blood stream (Fearnley, 1965). Human semen contains a substance which can activate the blood fibrinolytic system (von Kaulla and Shettles, 1953). Indeed, when human seminal fluid is ejaculated, it undergoes a process resembling the clotting and fibrinolysis of the blood, by coagulating then liquefying spontaneously. The coagulum is formed when a fibrinogenlike protein secreted by the seminal vesicles is acted upon by a clotting enzyme from the prostate (Mann, 1964). Coagulation is followed within about 20 minutes by liquefactionliquefaction of the clots by an enzyme assumed to come from the prostate (Huggins and Neal, 1942). This enzyme resembles plasmin in that it is a protease acting on a fibrin-like substrate, and that it is derived from an inactive precursor.

Thesis (Ph.D.)--Memorial University of Newfoundland, Faculty of Medicine, 1997. / Typescript. Bibliography: leaves [222]-256.

No description available.

Abstract not available

Graduation date: 1993

The effects of several hormones and inducers of intracellular messengers on plasminogen activator (PA) production and changes in embryonic size by cultured bovine embryos were evaluated. Day 8 embryos were cultured in Ham's F-12 with 1.5 mg/ml bovine serum albumin (BSA) containing different levels of progesterone (P), estradiol -17fl (E₂), dexamethasone (Dex), retinoic acid (RA), dibutyryl cyclic AMP (dbcAMP), or phorbol myristate acetate (PMA) for 5 days under paraffin oil in a humidified atmosphere of 5% CO₂ in air at 37°C. The concentrations of PA in the conditioned media were determined by a caseinolytic assay. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymography were used to determine the molecular weight of PA in the medium and in the embryo homogenate. Changes in embryonic size were determined by measuring overall embryo diameter (OD) at 24-h intervals. None of the hormones and agents tested herein had a significant effect on PA production. Dimethyl sulfoxide (DMSO) which was used to dissolve PMA significantly inhibited PA production during the first 72 h of culture. Time of culture, however, exerted a significant effect on PA production by cultured embryos. The production of this protease was low during the first 48 h, increased during 72 and 96 h, and either remained high or slightly decreased toward the end of the culture period. Furthermore, the peak production of PA was attained 48 h after hatching. The molecular weight of PA in the conditioned medium and embryo tissues suggested that the bovine embryo at this developmental stage produced an urokinase-type PA. With the exception of dbcAMP and PMA, the hormones tested in this study did not affect embryonic size. While dbcAMP decreased OD later in culture, PMA enhanced OD throughout culture. The mechanism by which dbcAMP and PMA modulated embryonic size is not clear. These results suggest that cultured bovine embryos produce urokinasetype PA in a time dependent manner and the production of this enzyme is independent of exogenous hormonal regulation. / Graduation date: 1990

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 73-90). Also available in print.

Living cells keep sensing the changes in their environments, mostly, via cell surface receptors for different ligands. Attachment-dependent cells are sensitive to alterations in extracellular matrix (ECM). ECM is not only required for cell survival, but also prerequisite for epidermal growth factor (EGF) to stimulate cell proliferation. The receptors for the majority of ECM components are integrins and the receptor for EGF is EGF receptor (EGFR). When bound by their ligands, integrins and EGFR induce signal transduction cascades composed of alternative pathways. A quantitative assessment of relative contributions of alternative pathways to one final cell signaling will help understand designing principles of the network. Unfortunately, a methodology for such assessment is still not available, partly because of lack of relatively mature mathematical models. On the other hand, in most biochemical cascades, existence of alternative pathways increases the complexity and thus the robustness of networks. The relationships between the topology and robustness of large-scale biochemical networks have been studied intensively recently. In small-scale networks, while feedback has been revealed as an important contributor for adaptation and robustness, the quantitative correlation between the topology/pathway redundancy of small networks and their robustness remains unknown. / In this thesis, apoptosis of bovine mammary gland epithelial cells was demonstrated to be induced when fibronectin, one of the major components of ECM, was degraded by overexpressed tPA via two potential ways: deprivation of attachment and the effects of fibronectin fragments. Secondly, a mathematical model for EGFR activation of the MAPK cascade, in which alternative pathways exist, was explored and it was found that the Shc-dependent pathway is both redundant and dominant. We hypothesize that the Shc-dependent pathway is important for EGFR to compete with other receptors, which need Shc to transduce cell signals; and this pathway is not aimed to increase the robustness of the EGFR cascade. Finally, for the general importance of alternative pathways to the network topology and robustness, several concepts have been proposed to decompose and quantitatively characterize the networks. We demonstrate that the pathnet score is a better assessment for robustness than the molecular connectivity.