Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diabetics often have elevated levels of serum lipids and cholesterol and increased risk of cardiovascular disease. Streptozotocin-induced diabetes was used to determine whether elevated serum cholesterol levels in diabetics are due to loss of control of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, which catalyzes the committed step in cholesterol synthesis. Strain A/ST female mice were fed 10% corn oil diets, half with 2% cholesterol. Experimental groups were injected with 9.0 mg streptozotocin / 100g body weight. Diabetes was confirmed by weight loss, elevated blood sugars, and enlarged spleens. Reductase activity was assayed spectrophotometrically. Serum cholesterol levels were determined by gas liquid chromatography. Both diabetic and control mice fed cholesterol had elevated serum cholesterol levels and decreased reductase activities. These observations suggest that HMG CoA reductase is not the primary control point in the control of serum cholesterol levels in diabetic mice. The increase in serum cholesterol in the SI mice was not more than in the control group, suggesting that increased serum cholesterol is not a key factor in the control of coronary heart disease and related diseases in diabetics. The HMG CoA reductase activity was reduced in both SI and control mice fed 2% cholesterol, but not significantly, possibly due to a small sample size. Other substances that control serum cholesterol are all density classes of lipoproteins (high, intermediate, low, and very low) as well as the chylomicrons. / Department of Biology

Thesis (M.P.H.)--University of Adelaide, Dept. of Public Health, 1998. / Includes bibliographical references (leaves 274-289).

Aside from an indirect effect of PPARgamma activation to reduce insulin resistance and to facilitate adiponectin release, PPARgamma agonist could also exert direct effects on blood vessels. I provided a first line of experimental evidence demonstrating that PPARgamma agonist rosiglitazone up-regulates the endothelin B receptor (ETBR) expression in mouse aortas and attenuates endothelin-1-induced vasoconstriction through an endothelial ET BR-dependent NO-related mechanism. ETBR up-regulation inhibits endothelin-1-induced endothelin A receptor (ETAR)-mediated constriction in aortas and mesenteric resistance arteries, while selective ETBR agonist produces endothelium-dependent relaxations in mesenteric resistance arteries. Chronic treatment with rosiglitazone in vivo or acute exposure to rosiglitazone in vitro up-regulate the ETsR expression without affecting ETAR expression. These results support a significant role of ETBR in contributing to the increased nitric oxide generation upon stimulation with PPARgamma agonist. This study provides additional explanation for how PPARgamma activation improves endothelial function. / Firstly, I demonstrated that adipocyte-derived adiponectin serves as a key link in PPARgamma-mediated amelioration of endothelial dysfunction in diabetes. Results from ex vivo fat explant culture with isolated arteries showed that PPARgamma expression and adiponectin synthesis in adipose tissues correlate with the degree of improvement of endothelium-dependent relaxation in aortas from diabetic db/db mice. PPARgamma agonist rosiglitazone elevates the adiponectin release and restores the impaired endothelium-dependent relaxation ex vivo and in vivo, in arteries from both genetic and diet-induced diabetic mice. The effect of PPARgamma activation on endothelial function that is mediated through the adiponectin- AMP-activated protein kinase (AMPK) cascade is confirmed with the use of selective pharmacological inhibitors and adiponectin -/- or PPARgamma+/- mice. In addition, the benefit of PPARgamma activation in vivo can be transferred by transplanting subcutaneous adipose tissue from rosiglitazone-treated diabetic mouse to control diabetic mouse. I also revealed a direct effect of adiponectin to rescue endothelium-dependent relaxation in diabetic mouse aortas, which involves both AMPK and cyclic AMP-dependent protein kinase signaling pathways to enhance nitric oxide formation accompanied with inhibition of oxidative stress. These novel findings clearly demonstrate that adipocyte-derived adiponectin is prerequisite for PPARgamma-mediated improvement of endothelial function in diabetes, and thus highlight the prospective of subcutaneous adipose tissue as a potentially important intervention target for newly developed PPARgamma agonists in the alleviation of diabetic vasculopathy. / To summarize, the present investigation has provided a few lines of novel mechanistic evidence in support for the positive roles of PPARgamma and PPARdelta activation as potentially therapeutic targets to combat against diabetic vasculopathy. / Type 2 diabetes mellitus and obesity represent a global health problem worldwide. Most diabetics die of cardiovascular and renal causes, thus increasing the urgency in developing effective strategies for improving cardiovascular outcomes, particularly in obesity-related diabetes. Recent evidence highlights the therapeutic potential of peroxisome proliferators activated receptor (PPAR) agonists in improving insulin sensitivity in diabetes. / While agonists of PPARalpha and PPARgamma are clinically used, PPARdelta is the remaining subtype that is yet to be a target for current therapeutic drugs. Little is available in literature about the role of PPARdelta in the regulation of cardiovascular function. The third part of my thesis focused on elucidating cellular mechanisms underlying the beneficial effect of PPARdelta activation in the modulation of endothelial function in diabetes. PPARdelta agonists restore the impaired endothelium-dependent relaxation in high glucose-treated aortas and in aortas from diabetic db/db mice through activation of a cascade involving PPARdelta, phosphatidylinositol 3-kinase, and Akt. PPARdelta activation increases Akt and endothelial nitric oxide synthase and nitric oxide production in endothelial cells. The crucial role of Akt is confirmed by selective pharmacological inhibitors and transient transfection of dominant negative Akt plasmid in these cells. Treatment with PPARdelta agonist GW501516 in vivo augments endothelial function in diabetic db/db and diet-induced obese mice. The specificity of GW501516 for PPARdelta is proven with the loss of its effect against high glucose-induced impairment of endothelium-dependent relaxation in aortas from PPARdelta knockout mice. In addition, oral administration of GW501516 in vivo fails to improve endothelial function in diet-induced obese PPARdelta deficient mice. / Tian, Xiaoyu. / Adviser: Huang Yu. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 132-165). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Diabetic cardiomyopathy (DCM), a disorder of the heart muscle, is one of the major and most rampant culprits claiming thousands and thousands of lives around the globe every year by interfering with the blood circulation and causing the development of heart failure eventually. The progression of the disease is asymptomatic and having a long latent period, and it is characterized functionally by ventricular dilation, diastolic dysfunction, interstitial fibrosis and cardiomyocytes hypertrophy. It was suggested the pathogenesis of the disease and the related complications are related to the effects of hyperglycemia on cardiomyocytes. So understanding the physiology of both the normal and pathological conditions, and the underlying mechanisms involved are of paramount importance to derive therapies to cope with this disease. However, it is difficult, if not impossible, to study the physiology in vivo using a live sample or to build a cellular model with adult cardiomyocytes due to the insufficient number of the cells harvested. This is not until the emergence of Embryonic Stem Cells (ESCs) that a cellular model with clinical sufficient number of cardiomyocytes could be built for investigation and drug screening. With a view to mimicking the situation of the Diabetic cardiomyopathy of the Type II Diabetes mellitus (DM) patients, mouse ESCs are used to differentiate into cardiomyocytes using the traditional hanging drop method to produce Embryoid body (EB). The cardiomyocytes were then enriched and plated so that different testing conditions could be applied. The effect of high glucose (HG), Insulin and the combination of high glucose and insulin were then analyzed. This was to show the significance of hyperglycemia, hyperinsulinemia due to insulin resistance and the role of insulin in hyperglycemia on cardiomyocytes respectively. The results agreed with previous findings that high glucose and insulin alone do induce cells apoptosis while the combination of insulin and glucose did decrease the number of apoptosis and while the co-culture of insulin with High dosage of glucose has shown to reduce the effect of hypertrophy. / published_or_final_version / Medicine / Master / Master of Medical Sciences

Thesis (Ph.D.)--University of Melbourne, Dept. of Medicine, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 308-353).

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliographical references.

Thesis (Ph.D.)--University of Western Australia, 2003.

Indiana University-Purdue University Indianapolis (IUPUI) / Medication adherence remains a problem among Type-2 diabetes (T2D) patients despite availability of effective treatments. Three analyses of extant data sets were conducted to examine barriers to using medication as prescribed as an alternate method to assess medication adherence: 1) development and psychometric evaluation of the Murage-Marrero-Monahan-Medication barriers (4M) scale to assess patients’ perceived barriers; 2) patient demographic factors associated with barriers to using medication as prescribed, and 3) the association between patients’ perceived barriers to medication use and cardiovascular disease (CVD) risk factor control.Twelve focus groups and a cross-sectional study of 362 T2D patients contributed to develop and evaluate psychometric properties of the 4M scale. A cross-sectional survey of 964 T2D patients was used for the other two studies. Analysis of covariance identified demographic factors associated with reported barriers. Multivariable logistic regression was used to identify barriers associated with CVD risk factors (glucose, blood pressure and lipids) categorized as either poor or good control. Exploratory factor analysis with Varimax rotation resulted in a 19-item 4M scale with acceptable psychometric properties. As a five-domain (or single-domain) structure, coefficient alpha ranged from 0.70 to 0.83 (0.92). Both structures demonstrated discriminant validity and known-group validity. Age was inversely associated with all identified barriers while income was inversely associated with poor communication with providers and side effects. A unit increase in the overall barrier mean score on the 4M scale was associated with 92% increase in the odds of having poor control of two or more CVD risk factors compared to good control of all three risk factors (adjusted OR=1.92, 95% CI: 1.16–3.17; p<0.05). The 4M scale demonstrated acceptable psychometric properties in assessing barriers to using medication among T2D patients. Poor medication adherence has been previously associated with CVD risk. In this study, greater barriers were associated with poorer control of CVD risk factors making barriers a potential alternative to medication adherence, whose current assessment methods are limited. The 4M scale has the advantage to identify specific barriers inhibiting medication use that can facilitate patient-provider discussions and the development of targeted interventions. / Some parts of this dissertation work were jointly funded by Program Announcement 04005 from the Centers for Disease Control and Prevention (Division of Diabetes Translation) and the National Institute of Diabetes and Digestive and Kidney Diseases. The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the funding agency(s).