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.

Thèse d'exercice : Médecine. Médecine générale : Paris 12 : 2005. / Titre provenant de l'écran-titre. Bibliogr. f. 61-68.

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.

The intent of this research was to identify if the degenerative changes within arteries in the endometrium (endometrial angiopathies) correlate with degenerative changes in the uterine arteries and can be used as a predictor of increased risk for uterine artery rupture (UAR). With this objective specimens from 20 mares that died from uterine artery rupture and 21 control mares that died from unrelated causes were obtained from cases submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) over a two-year period. Postmortem specimens of each mare were collected from the left and right uterine arteries at the origin, bifurcation, and distal to the bifurcation as well as full thickness uterine wall sections at five different sites. An additional sample was taken from the uterine artery at the site of rupture in the affected mares. Tissue samples were immersed in 10% neutral buffered formalin, routinely processed, and stained with hematoxylin and eosin, Masson’s Trichrome, and Verhoeff´s Van Gieson histochemical stains as well as a smooth muscle-actin immunohistochemical marker. Elastosis, fibrosis, and vascular smooth muscle cell degeneration were identified in this study as potential contributors of vascular degeneration and a scoring system was developed to differentiate the degrees of severity of these specific degenerative changes within the intima and media of the vascular wall. Based on the scoring system, sections of uterine arteries and endometrial arterioles were blindly examined and the scored changes recorded for statistical analysis. Although the degenerative changes in endometrial and uterine arteries were similar within each group, the results could not not be used to predict an increased risk for UAR. Furthermore, we determined the major changes in vascular pathology of the affected uterine arteries and show there is a significant difference in degenerative changes between specific layers of the vascular wall.