No description available.

<p>The progression of an inflammatory response is largely dictated by soluble<br />factors termed cytokines reknown for their redundant and pleiotropic nature in<br />modulation of both immune and stromal cells. Individual members of the<br />interleukin-6 (IL-6)-type cytokine family possess both unique and shared biological<br />activities. These cytokines may participate in tissue remodelling by promoting<br />reconstruction ofextracellular matrix (ECM) following nonspecific tissue damage by<br />inflammatory cells. Consistent with this view, these cytokines upregulate expression<br />of an ECM protease inhibitor, tissue inhibitor of metalloproteinases-1 (TIMP-1) and<br />thus may alter net enzymatic degradation of ECM. The overall goal of this thesis<br />is to examine mechanisms by which TIMP-1 is regulated by IL-6-type cytokines,<br />especially by the cytokine oncostatin M (OSM). The promoter of TIMP-1 has<br />therefore been studied in detail to address the mechanisms by which OSM (and IL-6<br />type cytokines) regulate the transcription of the TIMP-1 gene. The approaches<br />undertaken have included deletion analysis of the TIMP-1 gene nucleotide<br />sequences proximal to the start of transcription to define DNA sequences<br />necessary/sufficient for cytokine-induced TIMP-1 promoter activity. In addition, the<br />binding of nuclear factors to these DNA elements and cytokine-response elements, their expression and involvement in the regulation of TIMP-1 transcription have been explored.</p> <p>We have identified sequences proximal to the start of TIMP-1 transcription<br />that are necessary for maximal responsiveness to OSM and IL-6. Deletion analysis<br />of the proximal TIMP-1 promoter (-95 to +47 TIMP-1 sequences) has identified a<br />nucleotide sequence within -59 to -53 ofthe murine TIMP-1 promoter that harbours<br />an AP-1 consensus DNA binding element. This element is necessary for maximal<br />OSM or IL-6 induced promoter activity of TIMP1-CAT reporter gene constructs<br />transfected into human hepatoma HepG2 cells. OSM is the most potent stimulus<br />(approx. 11-fold for OSM, and 4-fold for IL-6) of this response and additional<br />sequences 3-prime to +1 ofthe TIMP-1 gene are also necessary for maximal OSM<br />responsiveness.</p> <p>Electrophoretic mobility shift assays demonstrated two gel-shifted complexes<br />which bind the TIMP-1 AP-1 site. An AP-1 gel-shifted complex is present in the<br />absence of cytokine stimulation ("complex 1"), while OSM and not other IL-6-type<br />cytokines, stimulated the formation of a second AP-1 gel shifted complex.<br />Nuclear factors binding to TIMP-1 AP-1 complex 1 include junB, junD and fosrelated<br />antigens. However, unlike complex1, c-fos is present and necessary for the<br />formation of the OSM-induced TIMP-1 AP-1 complex2. Consistent with this, OSM<br />is a potent inducerofc-fos protein expression among IL-6-type cytokines. Both the<br />formation of complex2 and c-fos expression require new protein synthesis. JunB<br />and junO are constitutively expressed, while the expression of fos-related antigens are induced in response to OSM. In addition, although PMA was also a potent<br />inducer of c-fos expression, induction of TIMP-1 promoter activity by the<br />combination of PMA and IL-6 was comparable to IL-6 alone and did not equal the<br />significantly higher induction by OSM. Within the same cells, OSM and IL-6 equally<br />induced STATDNA-binding activity. An Ets-consensus site (nucleotides -45 to -40)<br />flanking the 3-prime end of the AP-1 site is a weak binding site for Ets-related<br />nuclear factors, and an SP-1 site near +1 (-11 to -6) is a strong binding siteforSP1<br />nuclear factors and related SP-1 site binding proteins. No STAT nuclear factor<br />binding to the proximal TIMP-1 promoterwas detected. Taken together, the TIMP1<br />AP-1 site and c-fos represent a unique target of OSM signalling and activation of<br />AP-1 complexes (possibly containing c-fos) by OSM as well as sequences<br />downstream of TIMP-1 +1 contribute to maximal responsiveness of the promoter<br />to this cytokine among IL-6 family members.</p> <p>The contribution of c-fos to OSM-induced TIMP-1 expression was further<br />explored in murine cells. OSM stimulates the expression of c-fos and activates<br />STATs 1, 3 and 5 DNA-binding activity in murine fibroblasts. As observed in<br />human cells, OSM but not other IL-6-type cytokines upregulated c-fos expression<br />which participated in complexes binding the TIMP-1 AP-1 site. OSM was also<br />unique among IL-6 family members in activating STAT5 DNA-binding activity in<br />murine fibroblasts. However, in contrast to observations in human HepG2 cells,<br />deletion analysis of the TIMP-1 promoter showed that the AP-1 site (-59/-53) was<br />v not necessary for OSM-mediated upregulation of the TIMP-1 proximal promoter<br />activity over basal levels in murine NIH3T3 fibroblasts and co-transfection of a<br />dominant-negative of AP-1 had no effect. However, transfection of dominant-negative<br />STATs1, 3 or5 (especially STAT3) could diminish cytokine-induced TIMP1<br />promoter activity. In addition, c-Fos was dispensable for OSM-mediated<br />upregulation ofTIMP-1 mRNA levels as TIMP-1 expression was detected in wildtype<br />and c-fos knockout murine lung fibroblasts. Consistent with deletion analysis<br />ofthe TIMP-1 promoter in human cells, dominant-negative AP-1 expression vectors<br />abrogated OSM-mediated TIMP-1 promoter activity, while Stat-dominant negative<br />expression vectors did not. Taken together, the examination of murine and human<br />systems suggests that AP-1 and STAT nuclear factors can contribute to the<br />regulation of the TIMP-1 promoter.</p> / Doctor of Philosophy (PhD)

Call number: LD2668 .T4 1929 K51

Call number: LD2668 .T4 1930 M81

No description available.

Adult hypopituitarism is associated with increased mortality and morbidity mostly from cardiovascular disease. This thesis examines lipid profile, coronary risk, homocysteine level and endothelial function in a group of hypopituitary patients compared to matched controls. Triglycerides, total and LDL-cholesterol were elevated in patients of both genders; HDL-cholesterol was significantly reduced in females. HDL-cholesterol correlated negatively with adiposity. Total to HDL-cholesterol ratio was increased in both genders. The lipid abnormalities appear to be related to GH-deficiency either directly (LDL) or indirectly through increased central obesity (HDL). Absolute 5-years risk of a coronary event, using the Framingham risk equation, was greater in patients. Relative risk (RR) was higher in patients but not in the controls, mostly because female patients had significantly higher RR. RR for controls was not different from the local population. Lipid changes explained the increased risk in patients, particularly females. Plasma homocysteine was not increased in hypopituitary patients, and therefore does not appear to contribute to the increased cardiovascular mortality. Biochemical markers of endothelial dysfunction, e-selectin, ICAM-1, TM, and vWF, were higher in patients. Brachial artery EDD was lower in patients than controls. This difference in EDD was more marked in females, though it disappeared when comparing the oestrogen sufficient female patients with controls. However, the female patients who were not replaced with oestrogen continued to show a striking difference compared to oestrogen deficient control females, There was no difference in carotid IMT between patients of both genders and controls. EDD correlated inversely with ICAM-1; ICAM-1 correlated positively with e-selectin and negatively with IGF-1; e-selectin correlated positively with TM, vWF, and negatively with IGF-1; TM correlated positively with vWF and inversely with IGF-1. The results confirm significant endothelial dysfunction in hypopituitarism and suggest a role for GH-deficiency and oestrogen deficiency in endothelial dysfunction.

There is now unequivocal evidence that dietary behaviour is related to illness and risk of chronic diseases such as cardiovascular disease and cancer. Attempts to improve the nation's diet are based on providing information, assuming that given more information, the public will choose healthier diets. Many studies indicate, however, that nutrition knowledge has little association with dietary behaviour; but a review of the literature reveals that nutrition knowledge has been inadequately measured. In addition, dietary behaviour has been assessed in terms of food intake and not in relation to changes in, or readiness to change, food intake. Following the Introduction, this research begins, in Chapter 2, by reviewing the literature measuring nutrition knowledge. It is found that while many studies measure knowledge, typically the measure forms only part of the study which assesses either a particular subpopulation or a particular aspect of nutrition. In consequence, questionnaires are designed for a one-off and specific purpose and little attention is paid to the psychometric properties of the instrument. Dietary behaviour is measured with one of the well-established methods of assessing intake, the problems of which are acknowledged in the literature. Chapter 3 describes these methods with their shortcomings and use in psychological research. In response to these reviews, a comprehensive nutrition knowledge questionnaire was developed (in 1994) and intake was conceptualised in terms of dietary change, in keeping with psychologists' role in nutrition. Following the development and pilot study of this questionnaire (Chapter 4), its validity and reliability were assessed further in Chapter 5, with positive results. Significant differences were found between criterion groups (dietetic and computer science students), providing evidence of construct validity. Internal consistency correlations ranged from 0.50 to 0.92 and test-retest reliability correlations ranged from 0.80 to 0.98. This measure was then used (Chapter 6) to assess the level of nutrition knowledge among a large representative sample of British adults in a postal survey (in 1995). Nutrition knowledge was found to be poor concerning the dietary recommendations for meat, starchy foods, fruit and vegetables; the different types of fat (saturated, poly- and monounsaturated); and associations between diet and diseases, such as fruit and vegetables, heart disease and cancer. Both stages of change (using Prochaska and DiClemente's model) and consumption of fat, fruit and vegetables (to test the stages' validity) were also assessed as measures of dietary behaviour. Most respondents replied that they had been limiting their fat intake for more than 6 months, but not been thinking of increasing their fruit and vegetable intake. Multivariate analyses showed that being female, having more educational qualifications and being in a higher socioeconomic class were predictive of knowing more about nutrition and having a healthier dietary behaviour. Relationships between nutrition knowledge, stages of change and dietary intake were examined in Chapter 7 and significant associations identified. In contrast to this cross-sectional research, the final study in Chapter 8 was longitudinal and examined changes in nutrition knowledge and dietary behaviour over a one-year period (from 1993 to 1994). This study aimed to provide information on the extent to which healthier changes in dietary intake are related to increases in nutrition knowledge. While changes occurred in dietary intake (fat and sugar intake decreased significantly, the increases in fruit and vegetable consumption were insignificant), knowledge scores remained unchanged. The final chapter discusses the key findings of this research, its implications and areas worthy of future investigation. For example, the results from this research suggest that knowledge is an important factor in food choice and should not be discounted as a part of health promotion. It may also be useful to integrate the construct of knowledge into the social cognition models of dietary choice or indeed to develop a new model to include knowledge along with motivational constructs from the social cognition models.

No description available.

No description available.

No description available.