The tenn Acute Coronary Syndrome (ACS) encompasses a spectrum of patients who present with chest discomfort or other symptoms caused by myocardial ischemia or infarction. Since critical or acute care nurses care for such patients, they should have a thorough knowledge of ACS pathophysiology and current treatments for ACS The purpose of this research study is to explore and describe the knowledge level that the critical care nurses in a state hospital in East Texas feel they have regarding ACS. This study was quantitative, descriptive and contextual in design, in which a sample survey was performed, using a questionnaire based on a literature study. The response of most ofthe critical care nurses tested was that they felt they had insufficient knowledge. An in-service training session has been proposed to help improve the nurses' knowledge and expertise on ACS. / Health Studies / M.A. (Nursing Science)

It is well established that atherosclerosis, an inflammatory response to chronic injury in the blood vessel wall, plays a leading role in the development and progression of cardiovascular disease. Mineralocorticoid receptor (MR) over-activation has been implicated in atherosclerosis. In mineralocorticoid-target tissues, 11β- Hydroxysteroid dehydrogenase type 2 (11β-HSD2) inactivates glucocorticoids, conferring aldosterone specificity upon the normally unselective MR. Recent evidence suggests that 11β-HSD2 may also afford protection of MR in the cells of the vasculature, providing possible mechanisms by which MR activation may directly promote atherosclerosis. Consistent with this, Apoe-/-/11β-HSD2-/- double knockout (DKO) mice show accelerated atheroma development. The present thesis tested the hypothesis that inactivation of 11β-HSD2, allowing inappropriate activation of MR in cells of the vasculature, accelerates atherogenesis through promotion of a pro-inflammatory environment with increased endothelial cell expression of adhesion molecules and subsequent macrophage infiltration into plaques. DKO mice received either the MR antagonist eplerenone (200mg/kg/day) or vehicle in normal chow diet from 2 months of age for 12 weeks. Eplerenone significantly decreased atherosclerotic burden in brachiocephalic arteries of DKO mice, an effect that was accompanied by alterations in the cellular composition of plaques such that a more stable collagen- and smooth muscle cell- rich plaque was formed. Eplerenone treatment was also associated with a reduction in vascular inflammation as demonstrated by a significant reduction in macrophage infiltration into DKO plaques. The accelerated atherogenesis in DKO mice was clearly evident by 3 months of age, a time point at which Apoe-/- mice were completely lesion free. By 6 months, some Apoe-/- mice had developed lesions whilst all DKO mice at this age showed much larger plaques. Compared to Apoe-/- mice, the cellular composition of DKO plaques was altered favouring vulnerability and inflammation, with increased macrophage and lipid content and decreased collagen content. To investigate the possible underlying mechanisms responsible for increased inflammatory cell content, the expression of vascular cell adhesion molecule 1 (VCAM-1) was compared in DKO and Apoe-/- brachiocephalic arteries. VCAM-1 immunostaining was significantly greater on the endothelial cells of DKO arteries at 3 months compared to age-matched Apoe-/- mice. At 6 months, DKO and Apoe-/- mice had similar expression of VCAM-1. Finally, mouse aortic endothelial cells (MAECs) were used to investigate the mechanism of adhesion molecule up-regulation in the absence of 11β-HSD2. Both aldosterone and TNF-α, included as a positive control, dramatically increased VCAM-1 expression in MAECs. Spironolactone pre-treatment blocked the effect of aldosterone, suggesting an MR-mediated mechanism. Corticosterone alone had no effect on VCAM-1 expression. However, inhibition of 11β-HSD2 by pre-treatment with glycyrrhetinic acid allowed corticosterone to induce a significant increase in the number of VCAM-1-stained MAECs, demonstrating functional expression of 11β- HSD2 in MAECs. Consistent with 11β-HSD2 involvement, VCAM-1 up-regulation by corticosterone in the presence of glycyrrhetinic acid was reversed by blockade of MR with spironolactone. In conclusion, loss of 11β-HSD2 activity leading to inappropriate activation of MR in atherosclerotic mice promotes plaque vulnerability and increases vascular infiltration of macrophages which accelerates plaque growth, possibly through enhanced MR- mediated endothelial cell expression of VCAM-1.

Atherosclerosis and post-angioplasty neointimal proliferation, which are leading causes of cardiovascular morbidity and mortality, develop as a result of chronic or acute vascular injury producing inflammatory and proliferative responses in the vessel wall. Glucocorticoids, the stress hormones produced by the adrenal cortex, have anti-inflammatory and anti-proliferative characteristics and can also influence systemic cardiovascular risk factors. The systemic levels of these hormones are controlled by the hypothalamic pituitary adrenal axis. However, there is also a tissue-specific pre-receptor regulation of these hormones by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD); type 1 regenerates active glucocorticoids within the cells and type 2 inactivates glucocorticoids. Whilst it has been shown that the inhibition of 11β-HSD1 has favourable effect on cardiovascular risk factors and the inhibition of 11β-HSD2 results in hypertension; the effect of these enzymes on vascular lesion development is not known. The work described in this thesis tested the hypothesis that 11β-HSD1 inhibition reduces vascular lesion development due to improvement in cardiovascular risk factors, whereas 11β-HSD2 inhibition leads to adverse vascular remodelling. Apolipoprotein-E deficient (ApoE-/-) mice fed on western diet were used to study atherosclerosis, whereas neointimal proliferation was investigated using a well-established mouse model of wire-angioplasty. Vascular lesions were assessed using novel imaging and standard histological techniques. 11β-HSD1 inhibition reduced the size of atherosclerotic lesions and improved markers of plaque stability with a reduction in lipid content and increase in collagen content of the plaques. This was associated with a reduction in weight gain and blood pressure but without any effect on lipid profile. 11β-HSD1 inhibition did not produce any significant effect on neointimal proliferation in C57Bl/6J mice. However in ApoE-/- mice, 11β-HSD1 inhibition reduced neointimal proliferation with corresponding increase in size of patent lumen and with an associated reduction in macrophage content of neointimal lesions. 11β-HSD2 deletion produced an outward remodelling in un-injured vessels but there was no effect on neointimal proliferation after wire-angioplasty. Administration of a selective mineralocorticoid antagonist, eplerenone, reduced neointimal lesions significantly but to a similar degree in both C57Bl/6J and 11β-HSD2-/- mice, associated with a significant reduction in macrophage content of lesions but without any effect on blood pressure. Data in this thesis highlight the potential therapeutic application of 11β-HSD1 inhibition in reducing the size and vulnerability of atherosclerotic plaques and also reduction in neointimal proliferation (and hence post-angioplasty restenosis) in high risk patients with „metabolic syndrome‟ phenotype. The results also indicate that 11β-HSD2 has a limited, if any, role to play in the development of neointimal lesions.

Matrix metalloproteinase-2 (MMP-2, gelatinase A, type IV collagenase) is a member of a family of zinc-dependent metalloendopeptidases that functions in the degradation of elastin, collagens, and other components of extracellular matrix (ECM). Both secretion and activation of MMP-2 are elevated in human atherosclerotic lesions and abdominal aortic aneurysms (AAA). In this dissertation project, we sought to test the hypothesis that MMP-2 plays a critical role in both atherosclerosis and AAA. We also sought to determine the detailed mechanism. We first examined the atherosclerosis and AngII-induced AAAs development in MMP-2-/- x apolipoprotein (apoE)-/- mice in vivo. It was surprising that MMP-2 deficiency did not reduce the incidence of AngII-induced AAAs or the size of atherosclerosis in apoE-/- mice. However, the cellular and ECM content of atherosclerotic plaques were modified in MMP-2-/- x apoE-/- mice as compared to MMP-2+/+ x apoE-/- control mice. To explain the apparent paradox between this result and the hypothesis, we investigated the morphological characteristics of the aortic wall of MMP-2-/- mice. We detected an enhanced MMP-9 level in the aortic wall of MMP-2-/- x apoE-/- mice compared with MMP-2+/+ x apoE-/- mice. Interestingly, we also observed more branching of the elastin fibers in aortic wall of MMP-2-/- mice as compared with aorta of wild type mice. We also examined the behavior of macrophages from MMP-2-/- mice. Reduced adhesion, migration, and expression of integrin beta 3 were detected in MMP-2 deficient macrophages compared with wild type macrophages. Lastly, we examined whether MMP-2 deficiency in bone marrow-derived cells may influence AAAs and atherosclerosis using bone marrow transplantation technique. There was a significant reduction of both atherosclerosis development and AAAs formation in mice that were reconstituted MMP-2-/- bone marrow cells. In conclusion, the findings in this dissertation suggest that MMP-2 might play an important role in atherosclerosis and aneurysm through influencing inflammatory cell infiltration.

Atherosclerosis is a chronic inflammatory disease thought to be initiated by endothelial cell dysfunction. Research described in this dissertation is focused on the role of zinc deficiency in endothelial cell activation with an emphasis on the function of the transcription factors nuclear factor-κB (NF-κB), peroxisome proliferator activated receptor (PPAR), and the aryl hydrocarbon receptor (AhR), which all play critical roles in the early pathology of atherosclerosis. Cultured porcine aortic vascular endothelial cells were deprived of zinc by the zinc chelator TPEN and/or treated with the NF-κB inhibitor CAPE or the PPARγ agonist rosiglitazone, followed by measurements of PPARα expression, cellular oxidative stress, NF-κB and PPAR DNA binding, COX-2 and E-selectin expression, and monocyte adhesion. Cellular labile zinc deficiency increased oxidative stress and NF-κB DNA binding activity, and induced COX-2 and Eselectin gene expression, as well as monocyte adhesion in endothelial cells. CAPE significantly reduced the zinc deficiency-induced COX-2 expression, suggesting regulation through NF-κB signaling. PPAR can inhibit NF-κB signaling. Zinc deficiency down-regulated PPARα expression and PPAR DNA binding activity in endothelial cells. Zinc deficiency compromised PPARγ transactivation activity in PPARγ and PPRE co-transfected rat aortic vascular smooth muscle cells. Furthermore, rosiglitazone was unable to inhibit the adhesion of monocytes to endothelial cells during zinc deficiency. Most of these effects of zinc deficiency could be reversed by zinc supplementation. An in vivo study utilizing the atherogenic LDL-R-/- mouse model generally supported the importance of PPAR dysregulation during zinc deficiency. LDLR-/- mice were maintained for four weeks on either zinc deficient or zinc adequate diets. Half of the mice within each zinc group were gavaged daily with rosiglitazone during the last stage of the study. Selected inflammation and lipid parameters were measured. The anti-inflammatory properties of rosiglitazone were compromised during zinc deficiency. Specifically, rosiglitazone induced inflammatory genes (MCP-1) in abdominal aorta only during zinc deficiency, and adequate zinc was required for rosiglitazone to down-regulate pro-inflammatory markers such as iNOS in abdominal aorta of the mice. Rosiglitazone significantly up-regulated liver IκBα protein expression only in zinc adequate mice. Plasma data also suggest an overall pro-inflammatory environment during zinc deficiency and support the concept that zinc is required for proper anti-inflammatory or protective functions of PPAR. Zinc deficiency also altered PPAR-regulated lipid metabolism in LDL-R-/- mice. Specifically, zinc deficiency increased plasma total cholesterol, and non- HDL (VLDL, IDL and LDL)-cholesterol. Plasma total fatty acids tended to be increased during zinc deficiency, and rosiglitazone treatment resulted in similar changes in fatty acid profile in zinc deficient mice. FAT/CD36 expression in abdominal aorta was upregulated by rosiglitazone only in zinc-deficient mice. In contrast, rosiglitazone treatment markedly increased LPL expression only in zinc-adequate mice. These data suggest that in this atherogenic mouse model treated with rosiglitazone, lipid metabolism can be compromised during zinc deficiency. AhR is another transcription factor involved in the development and homeostasis of the cardiovascular system. Cultured porcine aortic endothelial cells were exposed to the AhR ligands PCB77 or beta-naphthoflavone (β-NF) alone or in combination with the zinc chelator TPEN, followed by measurements of the AhR responsive cytochrome P450 enzymes CYP1A1 and 1B1. Zinc deficiency significantly reduced PCB77- induced CYP1A1 activity and mRNA expression, as well as PCB77 or β-NF-induced CYP1A1 protein expression, which could be restored by zinc supplementation. These data suggest that adequate zinc is required for the activation of the AhR-CYP1A1 pathway. Impairment of the AhR pathway presents an additional mechanism by which zinc deficiency negatively affects transcription factor function and homeostasis of the vascular system. Taken together, zinc nutrition can markedly modulate the pathogenesis of inflammatory diseases such as atherosclerosis.

Any lipoproteins and cells present in the inflammatory environment of atherosclerotic plaques are likely to be exposed to high levels of oxidative stress. As 7,8-dihydroneopterin (7,8-NP) is synthesized by interferon-γ (IFN-γ)-activated macrophages, this pteridine is also thought to exist at sites of inflammation. 7,8-NP s in vivo role remains controversial, but numerous in vitro studies have identified a radical scavenging activity. The possibility of 7,8-NP protecting against oxidative damage in inflammatory environments like plaque was investigated in this thesis. Both human monocyte-derived macrophages (HMDMs) and low density lipoprotein (LDL) were used as substrates. The extent of protein hydroperoxide formation in each model, and 7,8-NP s effect on this process, were specifically studied since most previous research has focussed on lipid rather than protein peroxidation. For the first time, neopterin (including oxidized 7,8-NP) was also directly detected by high performance liquid chromatography in the inflammatory environments of 19 pus and two atherosclerotic plaque samples. Peak concentrations even reached the low micromolar range. The positive correlation identified in the pus between neopterin and a well known antioxidant, vitamin E, further hinted at a potential antioxidant function. However, no significant association was noted between neopterin and markers of protein or lipid oxidation. Exposure of HMDMs to the AAPH peroxyl radical generator resulted in significant quantities of lipid hydroperoxides but not protein hydroperoxides, as detected by the FOX assays. This is likely due to the large accumulation of polyunsaturated fatty acidrich lipid in the primary HMDMs during differentiation in 10% human serum and is of relevance to atherosclerotic plaque, where macrophages also become lipid-loaded. The addition of up to 200μM 7,8-NP failed to prevent AAPH-induced lipid peroxidation and was also unable to inhibit a loss of cellular thiols or viability. This lack of effect suggests the damaging peroxyl radicals are not being scavenged by 7,8-NP. The high lipid content of HMDM cells appears to cause the AAPH and/or 7,8-NP to localize to a cellular site, where they are unable to interact. Macrophage-mediated oxidation of LDL in iron(II)-supplemented Hams F10 was associated with the formation of 30-40 moles of protein hydroperoxides per mole of LDL. The close parallel between protein and lipid peroxidation supports the theory that lipid-derived radicals are involved in protein hydroperoxide formation on LDL and indicates that protein hydroperoxides are an early product of LDL oxidation. Their detection during exposure of LDL to both the THP-1 macrophage cell line and primary HMDM cells confirms that protein hydroperoxides are also a normal consequence of macrophage-mediated LDL oxidation. Incubation of LDL with micromolar 7,8-NP prevented macrophage-mediated protein hydroperoxide formation in a concentration-dependent manner. Lipid oxidation and vitamin E loss were similarly inhibited by 7,8-NP during the cell-mediated attack of LDL. Kinetic analysis revealed protection due to extension of the lag phase, with 7,8-NP depletion and initiation of the propagation phase coinciding. This supports a radical scavenging activity for 7,8-NP, resulting in protection of the entire LDL particle. By contrast, the release of nanomolar quantities of 7,8-NP by IFN-γ-stimulated THP-1 macrophages failed to prevent LDL oxidation. HMDMs activated by IFN-γ did significantly inhibit LDL oxidation, including protein hydroperoxide formation, for up to 48 hours but this antioxidant effect was not due to the de novo synthesis of 7,8-NP. These results indicate that both the prevalence of protein hydroperoxides, and the ability of 7,8-NP to act as an antioxidant, depend on the system under investigation. Neopterin exists in inflammatory environments but, considering the lack of protection against AAPH-mediated HMDM oxidation and the 7,8-NP concentration required to inhibit macrophage-mediated LDL oxidation, strong evidence for an antioxidant activity of 7,8-NP in atherosclerotic plaque is currently lacking.

Atherosclerosis is a chronic inflammatory disease of arterial blood vessels, characterized by deposition of lipoproteins in the arterial wall. Atherosclerotic plaques form preferentially in distinct regions of the vasculature such as branch points, curvatures and bifurcations, suggesting that local hemodynamic forces may contribute to disease susceptibility. Shear stress imparted on endothelial cells (ECs) by the flowing blood has been shown to modulate gene expression and remodelling of the artery. In this thesis, an in vitro model was established to recreate the contrasting environments found in atherosclerosis-prone and atherosclerosis-resistant regions of the vasculature to demonstrate a direct causal-relationship between shear stress and expression of endothelial nitric oxide synthase (eNOS) and p65 in ECs. In vitro assessment of cell shape and expression patterns of these anti- and atherogenic genes demonstrated that shear stress can induce cell morphology and gene expression patterns that are similar to ECs in atherosclerosis-prone and atherosclerosis-resistant regions of the mouse vasculature. Regulation of eNOS transcription by shear stress was demonstrated using a transgenic mouse model and in vitro heterogeneous nuclear RNA (hnRNA) quantification. Similar to ECs in atherosclerosis-prone regions, epithelial cells lining the small intestine lumen express high levels of p65. To investigate the effects of p65 expression levels on constitutive and tumour necrosis factor α (TNFα)-induced nuclear factor-κB (NF-κB) signalling, p65 expression was suppressed in HeLa cells by RNA interference. Lower p65 expression resulted in reduced TNFα-induced expression of NF-κB target genes, including many subunits of inhibitor of nuclear factor κB (IκB), demonstrating modulation of NF-κB priming by p65 expression levels. Suppression of p65 also affected constitutive expression levels of IκB, and resulted in re-setting of the NF-κB/IκB equilibrium. Experiments using inhibitors of canonical NF-κB signalling found that basal expression of NF-κB components is independent of nuclear factor κB kinase β (IKKβ) activity and proteasome-mediated degradation of IκBα. Together, these studies elucidate the mechanism of flow-mediated gene regulation and the effect of resulting changes in p65 expression on NF-κB signalling.

Endothelial cells (ECs) and smooth muscle cell (SMC) play a key part during development of fibrosis in the intima being partly responsible for synthesis of matrix metalloproteinase (MMPs) and various regulators and substrates of these enzymes. Omega-3 (n-3) polyunsaturated fatty acids (PUFA) consumption, mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has beneficial effects on atherosclerosis but its effect on the development of fibrosis is relatively unknown. <i>Objective:</i> Determine the effects of EPA and DHA, alone or in combination, on fibrosis-related factors in aortic SMCs (AoSMCs) and human umbilical vein ECs (HUVECs) and human aortic ECs (HAECs). <i>Results:</i> Treatment of cells with/without 10 μM DHA, EPA, oleic acid (OA) or vehicle control (VC) altered expression of MMPs, regulators and substrates of MMPs and inflammatory cytokines. EPA increased the α-actin:β-actin ratio indicative of a more contractile SMC phenotype and gelatinase (MMP-2 and -9) activity in HUVECs. In aortic cells, EPA and DHA decreased uPAR mRNA and protein expressions. DHA, EPA and DHA: EPA (at 3:1 and 1:1) decreased SMC migration, this did not involve uPA/plasmin activity. <i>Conclusion:</i> EPA and DHA could decrease inflammatory cytokines and the fibrogenic environment in atherosclerotic lesions by decreasing MMP expression and activity. These fatty acids may also reduce SMC migration and proliferation, independently of uPA/plasmin activity, potentially reducing SMC build up in the intima. This could possibly prevent and/or show plaque progression and increase the stability of advanced plaques.

Stroke is one of the leading causes of death in the world, resulting mostly from the sudden rupture of atherosclerotic plaques. From a biomechanical view, plaque rupture can be considered as a mechanical failure caused by extremely high plaque stress. In this PhD project, we are aiming to predict 3D plaque stress based on in-vivo MRI by using fluid structure interaction (FSI) method, and provide information for plaque rupture risk assessment. Fluid structure interaction was implemented with ANSYS 11.0, followed by a parameter study on fibrous cap thickness and lipid core size with realistic carotid plaque geometry. Twenty patients with carotid plaques imaged by in-vivo MRI were provided in the project. A framework of reconstructing 3D plaque geometry from in-vivo multispectral MRI was designed. The followed reproducibility study on plaque geometry reconstruction procedure and its effect on plaque stress analysis filled the gap in the literature on imaging based plaque stress modeling. The results demonstrated that current MRI technology can provide sufficient information for plaque structure characterization; however stress analysis result is highly affected by MRI resolution and quality. The application of FSI stress analysis to 4 patients with different plaque burdens has showed that the whole procedure from plaque geometry reconstruction to FSI stress analysis was applicable. In the study, plaque geometries from three patients with recent transient ischemic attack were reconstructed by repairing ruptured fibrous cap. The well correlated relationship between local stress concentrations and plaque rupture sites indicated that extremely high plaque stress could be a factor responsible for plaque rupture. Based on the 20 reconstructed carotid plaques from two groups (symptomatic and asymptomatic), fully coupled fluid structure interaction was performed. It was found that there is a significant difference between symptomatic and asymptomatic patients in plaque stress levels, indicating plaque stress could be used as one of the factors for plaque vulnerability assessment. A corresponding plaque morphological feature study showed that plaque stress is significantly affected by fibrous cap thickness, lipid core size and fibrous cap surface irregularities (curvedness). A procedure was proposed for predicting plaque stress by using fibrous cap thickness and curvedness, which requires much less computational time, and has the potential for clinical routine application. The effects of residual stress on plaque stress analysis and arterial wall material property characterization by using in-vivo MRI data were also discussed for patient specific modeling. As the further development, histological study of plaque sample has been combined with conventional plaque stress analysis by assigning material properties to each computational element, based on the data from histological analysis. This method could bridge the gap between biochemistry and biomechanical study of atherosclerosis plaques. In conclusion, extreme stress distributions in the plaque region can be predicted by modern numerical methods, and used for plaque rupture risk assessment, which will be helpful in clinical practice. The combination of plaque MR imaging analysis, computational modelling, and clinical study/ validation would advance our understandings of plaque rupture, prediction of future rupture, and establish new procedures for patient diagnose, management, and treatment.

Reduction of cholesterol ester (CE) from lipid burden lesion-associated macrophage foam cells has been shown to reduce plaque volumes. Hydrolysis of CE to free cholesterol (FC) in macrophages is an essential step for removal of CE from the macrophage and its transport to the liver by high density lipoprotein (HDL) for further metabolism. Since CE must again be hydrolyzed into FC in the liver catalyzing this hydrolysis, it becomes imperative to find the identity of these enzymes. In this study the role of key enzyme in catalyzing the hydrolysis of CE to FC, neutral cholesterol ester hydrolase (CEH) was evaluated. Further, ability of this CEH to hydrolyze CE delivered via scavenger receptor BI (SR-BI) or SR-BII was also monitored. CE hydrolysis and FC efflux were monitored from cells transfected with CEH expression vector. No significant difference was noted in either the intracellular CEH activity or FC efflux between cells transfected with an empty vector or a CEH expression vector. Further no difference was seen when experiments were repeated with cells stably transfected with SR-BI or SR-BII. Future experiments with more optimization of the cells system used will be required to reach any conclusions on the role of CEH in hydrolyzing HDL-CE delivered via SR-BI/BII.