Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 1996. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 90-97). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 90-97). Also available on the Internet.

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 1996. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Düsseldorf, Universiẗat, Diss., 2001.

Abstract Numerous adverse effects and health problems are associated with smoking, but the mechanisms of the adverse effects of smoking on skin are not well documented. The aim of the present study was to elucidate the effects of smoking on the structure, metabolism and appearance of skin. The study population consisted of 98 Finnish males, of whom 47 were current smokers and 51 non-smokers. The main parameters under evaluation were the appearance and physical qualities of skin, including skin wrinkling, thickness and elasticity. Biochemical analyses were performed to assess the rate of type I and III collagen biosynthesis as well as the degradation of the extracellular matrix (ECM) of skin in terms of matrix metalloproteinase levels (MMPs). To compare the morphology of skin between the groups, histological and immunohistological studies were performed, including assessments of the proportional area and width of dermal elastic fibres. The results revealed decreased synthesis of type I and III collagens in smokers as well as changes in the regulatory mechanisms which control the turnover of these and other extracellular matrix proteins. The level of matrix metalloproteinase -8 (collagenase-2), a protease degrading both type I and type III collagen, in suction blister fluid was significantly higher in smokers, indicating enhanced degradation of these collagens. In skin tissue samples, the levels of the active forms of MMP-8 and MMP-9 were significantly lower in smokers compared to non-smokers. Serum levels of MMP-8 were slightly but not significantly higher in smokers, whereas the levels of the matrix metalloproteinases MMP-2 and MMP-9 (72-kDa and 92-kDa gelatinase, respectively) were significantly higher in smokers compared to non-smokers. Salivary MMP-8 and MMP-9 were lower in smokers compared to non-smokers, but only the latter showed a statistically significant difference. The levels of the tissue inhibitor of matrix metalloproteinases (TIMP-1) were significantly lower in the suction blister fluid of smokers compared to non-smokers. In general, there were no significant differences in skin thickness and elasticity or regeneration of barrier function, nor in the amount or width of elastic fibres between the groups. We did not observe significant differences in skin wrinkling between smokers and non-smokers, but smokers looked older than their age compared to non-smokers. It can be concluded that the rate of type I and III collagen synthesis in skin is decreased and the regulation of ECM turnover is altered in smokers, which may lead to deterioration of the tensile strength and resiliency of skin in the long term, even though no morphological changes were detected in the present study.

At the Castle Creek study area a remarkably well exposed section in the Isaac Formation, Windermere Supergroup, was measured to document potential lateral and vertical changes in facies. Here, a consistent lateral succession of facies was observed consisting of matrix-poor sandstone to clayey sandstone to bipartite bed to sandy claystone, collectively overlain by a thin-bedded turbidite and mudstone cap. These changes are interpreted to reflect particle settling in a negligibly-sheared sand-mud suspension following detachment from the margins of an avulsion jet. Vertically, similar facies stack to form packages 2-7 beds thick implying temporary stabilization of jet-margin dynamics. At a larger scale facies stack to form three stratal assemblages. SA-1: intercalated matrix-rich and matrix-poor strata and SA-2: matrix-rich strata stack vertically and laterally but then are sharply overlain everywhere by classical turbidites of SA-3, indicating a dramatic change from deposition immediately downflow of an avulsion node to conventional levee deposition.

All developing embryos contain an extracellular matrix (ECM) consisting of proteins, glycoproteins, and proteoglycans. These components are important for morphogenetic processes such as cell migration, cell differentiation and cell death. The ECM of the starfish, Pisaster ochraceus, consists of three major components: A hyaline layer which coats the external surface of the embryo; a basal lamina which lines the basal surfaces of the epithelia; and a blastocoelic component which fills the embryonic cavity or blastocoel. Observations of chemically fixed asteroid embryos have revealed the hyaline layer to contain five sub-layers of fibrous strands encrusted with amorphous material. Strands of a similar nature form a meshwork within the fluid-filled blastocoel. Recent studies of the living embryo, however, have suggested that the ECM within the blastocoel of echinoderms, including the asteroid, is a gel-like substance and not a fluid with extracellular fibres. Since artefacts imposed by chemicals such as aldehydes and osmium are well documented, a method of preservation, which does not involve the use of these chemicals, may resolve the apparent conflict over the nature of the ECM of the asteroid embryo. Freeze substitution, an expensive cryofixation technique which has proven successful in fixing vertebrate tissue, does not require the use of aldehydes and osmium. The initial objective of this study was to devise an inexpensive, easily employable freeze substitution technique which would allow good preservation of cellular and extracellular elements of the embryonic starfish, Pisaster ochraceus. A plunge freezing apparatus was constructed which consisted of a Dewer flask filled with liquid nitrogen, a small cup was filled with cryogen and inserted into the nitrogen, and a motor which constantly stirred the cryogen. Embryos were isolated on copper freeze-fracture grids and plunged into the cryogen. After considering four different cryogens and four separate cryoprotectants, cryoprotecting asteroid embryos with propylene glycol and plunging them into supercooled propane was found to provide optimal preservation. Frozen embryos were freeze substituted in anhydrous ethanol at -90 °C, osmicated, and embedded for ultrastructural and histochemical analysis. Following freeze substitution, the blastocoel appears to contain a gel-like substance, rich in sulfated GAG's, with extracellular fibres and not a fluid with fibres. In addition, the hyaline layer was found to consist of at least six sub-layers of greater thickness than was seen in chemically fixed embryos. Histochemical studies demonstrated that both sulfated and unsulfated GAG's were present in these layers. The morphological differences among the sub-layers suggest that some sub-layers may have unique functions while others may have functions shared by other sub-layers. Freeze substitution also revealed the presence of microvillus associated bodies, structures which may represent major attachment points of the hyaline layer to the epithelium. Although the fixation of asteroid embryos by freeze substitution is a lengthy process, taking four to five days, the resulting preservation, particular!ly of the ECM components, justifies its use over chemical fixations. Material preserved by freeze substitution can be used for histochemical studies and, since aldehydes and heavy metals are not necessary for successful preservation, may also prove useful for immunocytochemical studies. / Medicine, Faculty of / Graduate