• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 165
  • 32
  • 23
  • 23
  • 11
  • 6
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • Tagged with
  • 294
  • 294
  • 294
  • 62
  • 62
  • 58
  • 51
  • 40
  • 39
  • 29
  • 28
  • 26
  • 25
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Ultrasonic Pulse Wave Imaging for in vivo Assessment of Vascular Wall Dynamics and Characterization of Arterial Pathologies

Li, Ronny Xi January 2016 (has links)
Arterial diseases such as hypertension, carotid stenosis, and abdominal aortic aneurysm (AAA) may progress silently without symptoms and contribute to acute cardiovascular events such as heart attack, stroke, and aneurysm rupture, which are consistently among the leading causes of death worldwide. The arterial pulse wave, regarded as one of the fundamental vital signs of clinical medicine, originates from the heart and propagates throughout the arterial tree as a pressure, flow velocity, and wall displacement wave, giving rise to the natural pulsation of the arteries. The dynamic properties of the pulse wave are intimately related to the physical state of the cardiovascular system. Thus, the assessment of the arterial wall dynamics driven by the pulse wave may provide valuable insights into vascular mechanical properties for the early detection and characterization of arterial pathologies. The focus of this dissertation was to develop and clinically implement Pulse Wave Imaging (PWI), an ultrasound elasticity imaging-based method for the visualization and spatio-temporal mapping of the pulse wave propagation at any accessible arterial location. Motion estimation algorithms based on cross-correlation of the ultrasound radio-frequency (RF) signals were used to track the arterial walls and capture the pulse wave-induced displacements over the cardiac cycle. PWI facilitates the image-guided measurement of clinically relevant pulse wave features such as propagation speed (pulse wave velocity, or PWV), uniformity, and morphology as well as derivation of the pulse pressure waveform. A parametric study investigating the performance of PWI in two canine aortas ex vivo and 10 normal, healthy human arteries in vivo established the optimal image acquisition and signal processing parameters for reliable measurement of the PWV and wave propagation uniformity. Using this framework, three separate clinical feasibility studies were conducted in patients diagnosed with hypertension, AAA, and carotid stenosis. In a pilot study comparing hypertensive and aneurysmal abdominal aortas with normal controls, the AAA group exhibited significantly higher PWV and lower wave propagation uniformity. A “teetering” motion upon pulse wave arrival was detected in the smaller aneurysms (< 5 cm in diameter) but not in the larger aneurysms (> 5.5 cm in diameter). While no significant difference in PWV or propagation uniformity was observed between normal and hypertensive aortas, qualitative differences in the pulse wave morphology along the imaged aortic segment may be an indicator of increased wave reflection caused by elevated blood pressure and/or arterial stiffness. Pulse Wave Ultrasound Manometry (PWUM) was introduced as an extension of the PWI method for the derivation of the pulse pressure (PP) waveform in large central arteries. A feasibility study in 5 normotensive, 9 pre-hypertensive, and 5 hypertensive subjects indicated that a significantly higher PP in the hypertensive group was detected in the abdominal aorta by PWUM but not in the peripheral arteries by alternative devices (i.e. a radial applanation tonometer and the brachial sphygmomanometer cuff). A relatively strong positive correlation between aortic PP and both radial and brachial PP was observed in the hypertensive group but not in the normal and pre-hypertensive groups, confirming the notion that PP variation throughout the arterial tree may not be uniform in relatively compliant arteries. The application of PWI in 10 stenotic carotid arteries identified phenomenon such as wave convergence, elevated PWV, and decreased cumulative displacement around and/or within regions of atherosclerotic plaque. Intra-plaque mapping of the PWV and cumulative strain demonstrated the potential to quantitatively differentiate stable (i.e. calcified) and vulnerable (i.e. lipid) plaque components. The lack of correlation between quantitative measurements (PWV, modulus, displacement, and strain) and expected plaque stiffness illuminates to need to consider several physiological and imaging-related factors such as turbulent flow, wave reflection, imaging location, and the applicability of established theoretical models in vivo. PWI presents a highly translational method for visualization of the arterial pulse wave and the image-guided measurement of several clinically relevant pulse wave features. The aforementioned findings collectively demonstrated the potential of PWI to detect, diagnose, and characterize vascular disease based on qualitative and quantitative information about arterial wall dynamics under pathological conditions.
182

Association of Sleep Duration and Quality with Activation of Two Neuroendocrine Systems: Hypothalamic-Pituitary-Adrenal Axis and Sympathetic Nervous System. The Multi-Ethnic Study of Atherosclerosis (MESA)

Castro-Diehl, Olga Cecilia January 2016 (has links)
Many studies have shown that short sleep duration and/or poor sleep quality is associated with increasing rates of cardiovascular (CVD) mortality and morbidity. One hypothesized explanation for this association has been that sleep loss is a type of chronic stress that induces dysregulation of biological systems that ultimately increase the risk of CVD. One biological system that has been thought to link sleep loss and CVD is the hypothalamus-pituitary-adrenal (HPA) axis. A number of studies using small or convenience samples have addressed the effects of sleep deprivation on cortisol. Only a few studies have examined the association of habitual short sleep duration and/or poor sleep quality with changes in the diurnal cortisol in population based-samples; those studies vary in their methodology and in findings. Another biological system that has been thought to link sleep loss and CVD is the autonomic nervous system (ANS), through overactivation of the sympathetic nervous system (SNS) and/or probably a withdrawal of the parasympathetic nervous system. Experimental studies have shown an association between the sleep stages and markers of the sympathetic system. However, very few studies of habitual sleep duration/sleep quality and ANS markers have been conducted. Even fewer studies have examined the association of habitual sleep duration and/or sleep quality and ANS responses to a stress challenge in a population-based sample. The findings again have been inconsistent probably due to the use of different methodology and different samples. This dissertation used measures of salivary diurnal cortisol as well as cortisol responses to a stress challenge protocol to assess the relationship of habitual sleep duration and/or sleep quality with diurnal cortisol profile in natural conditions and in response to a stress challenge protocol in a laboratory setting. Diurnal cortisol was assessed from up to 16 samples of salivary cortisol for two days. Cortisol responses to a stress challenge were assessed from four salivary samples taken during the stress challenge that was performed in a different day than the diurnal cortisol collection. To examine the relationship of habitual sleep duration and/or sleep quality and markers of the ANS, this dissertation used continuous cardiovascular measures (heart rate and heart rate variability) and four salivary amylase samples obtained during the stress challenge. The stress challenge included mental stress and orthostatic stress. Sleep duration and sleep efficiency (an objective measure of sleep quality) were assessed from 7-day actigraphy and sleep diaries. Insomnia symptoms (a subjective measure of sleep quality) were also assessed using a questionnaire that included the Women’s Health Initiative Insomnia rating scale (WHIIRS). We used mixed models so as to account for the repeated measures of diurnal salivary cortisol levels as well as the responses (reactivity and recovery) to the stress challenge tests. Chapter 1 presents an introduction to this dissertation discussing the relationship between short sleep duration and/or poor sleep quality and CVD morbidity and mortality. Chapter 2 presents a systematic literature review of studies of the association between habitual sleep duration and/or sleep efficiency and markers of neuro-endocrine systems: HPA and ANS. These are plausible mechanisms that link short and/or poor sleep to CVD morbidity and mortality. Chapter 3 presents our analyses of the relationship between short sleep duration and/or poor sleep quality and features of the diurnal cortisol. We hypothesized that those participants whose slept < 6 hours per night or whose sleep efficiency was < 85% would have higher cortisol levels on awakening, flatter cortisol awakening responses (CAR), and higher evening cortisol levels than participants who slept longer or slept better. We found that short sleepers had higher evening cortisol than the longer sleepers and that this association persisted after the adjustment for several known confounders. In chapter 4, we examined how the same groups of participants responded in terms of hormones (cortisol and amylase) and cardiovascular indices (heart rate (HR) and HR variability (HRV)) to a stress challenge test. We hypothesized that those participants who slept for a shorter time or whose sleep was of poorer quality would have more exaggerated responses to and less recovery from a stress challenge test than participants who slept longer or slept better. We found that participants with insomnia had exaggerated high frequency-HRV (HF-HRV) orthostatic reactivity. In an extended analysis, we found that participants who slept less than 7 hours/night had exaggerated heart rate reactivity to a mental stress test compared to participants who slept 7 or more hours/night, but this association was attenuated after adjustment for naps. Paradoxically, we also found that participants who slept less than 7 hours had higher HF-HRV recovery from mental stress compared to longer sleepers (≥7 hours). Short sleep duration or low sleep efficiency was not associated with cortisol or amylase responses to the stress challenge protocol. These findings suggest that sustained high evening cortisol levels and cardiovascular responses to a stress challenge may be among the mechanisms linking short/poor sleep and CV disease.
183

Prognostic Modeling in the Presence of Competing Risks: an Application to Cardiovascular and Cancer Mortality in Breast Cancer Survivors

Leoce, Nicole Marie January 2016 (has links)
Currently, there are an estimated 2.8 million breast cancer survivors in the United States. Due to modern screening practices and raised awareness, the majority of these cases will be diagnosed in the early stages of disease where highly effective treatment options are available, leading a large proportion of these patients to fail from causes other than breast cancer. The primary cause of death in the United States today is cardiovascular disease, which can be delayed or prevented with interventions such as lifestyle modifications or medications. In order to identify individuals who may be at high risk for a cardiovascular event or cardiovascular mortality, a number of prognostic models have been developed. The majority of these models were developed on populations free of comorbid conditions, utilizing statistical methods that did not account for the competing risks of death from other causes, therefore it is unclear whether they will be generalizable to a cancer population remaining at an increased risk of death from cancer and other causes. Consequently, the purpose of this work is multi-fold. We will first summarize the major statistical methods available for analyzing competing risk data and include a simulation study comparing them. This will be used to inform the interpretation of the real data analysis, which will be conducted on a large, contemporary cohort of breast cancer survivors. For these women, we will categorize the major causes of death, hypothesizing that it will include cardiovascular failure. Next, we will evaluate the existing cardiovascular disease risk models in our population of cancer survivors, and then propose a new model to simultaneously predict a survivor's risk of death due to her breast cancer or due to cardiovascular disease, while accounting for additional competing causes of death. Lastly, model predicted outcomes will be calculated for the cohort, and evaluation methods will be applied to determine the clinical utility of such a model.
184

Cardiovascular tonic effects of compound formula of Radix Salviae miltiorrhizae and Radix Puerariae.

January 2003 (has links)
Leung Lai-Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 110-113). / Abstracts in English and Chinese. / Abstract English --- p.i / Chinese --- p.iii / Acknowledgments --- p.v / Table of contents --- p.vi / List of Tables --- p.ix / List of Figures --- p.x / List of Abbreviations --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Establishment of compound formulation --- p.4 / Chapter 2.1 --- Formulation research --- p.4 / Chapter 2.2 --- Aqueous extract preparation --- p.6 / Chapter 2.2.1 --- Materials and Methods --- p.6 / Chapter 2.2.2 --- Results --- p.7 / Chapter 2.2.3 --- Discussion --- p.9 / Chapter 2.3 --- Preliminary test --- p.10 / Chapter 2.3.1 --- Materials and Methods --- p.10 / Chapter 2.3.2 --- Results --- p.12 / Chapter 2.3.3 --- Discussion --- p.14 / Chapter Chapter 3 --- Quality Control --- p.15 / Chapter 3.1 --- HPLC standardization --- p.16 / Chapter 3.2 --- Materials and Methods --- p.19 / Chapter 3.3 --- Results --- p.20 / Chapter 3.4 --- Discussion --- p.28 / Chapter Chapter 4 --- Antioxidant study --- p.29 / Chapter 4.1 --- Red blood cell hemolysis model --- p.30 / Chapter 4.1.1 --- Materials and Methods --- p.30 / Chapter 4.1.2 --- Results --- p.30 / Chapter 4.1.3 --- Discussion --- p.32 / Chapter 4.2 --- Ischemia-Reperfusion on Langendorff --- p.33 / Chapter 4.2.1 --- Materials and Methods --- p.34 / Chapter 4.2.2 --- Results --- p.37 / Chapter 4.2.3 --- Discussion --- p.60 / Chapter Chapter 5 --- Vasodilation study --- p.61 / Chapter 5.1 --- Vasodilation in organ bath --- p.63 / Chapter 5.1.1 --- Materials and Methods --- p.63 / Chapter 5.1.2 --- Results --- p.65 / Chapter 5.1.3 --- Discussion --- p.79 / Chapter 5.2 --- Endothelium dependent vasodilation --- p.80 / Chapter 5.2.1 --- Materials and Methods --- p.80 / Chapter 5.2.2 --- Results --- p.83 / Chapter 5.2.3 --- Discussion --- p.95 / Chapter Chapter 6 --- Anti-platelet study --- p.96 / Chapter 6.1 --- CFU-MK plasma clot colony assay --- p.97 / Chapter 6.2 --- Materials and Methods --- p.97 / Chapter 6.3 --- Results --- p.100 / Chapter 6.4 --- Discussion --- p.103 / Chapter Chapter 7 --- Discussions and prospects --- p.104 / Chapter 7.1 --- Discussions --- p.104 / Chapter 7.2 --- Prospects --- p.107 / Chapter 7.2.1 --- TCM capsule with GMP --- p.107 / Chapter 7.2.2 --- Clinical Trial of the capsule --- p.109 / References --- p.110
185

Cerebrovascular effects of a danshen and gegen formulation. / CUHK electronic theses & dissertations collection

January 2012 (has links)
丹參和葛根為我國民間常用的傳統藥材, 常用於心血管疾病的治療。本試驗主要研究丹參葛根複方(DG, 7:3)對大鼠基底動脈的舒張作用 及腦保護作用。 / 上述所有藥物對U46619預收縮的基底動脈環呈現濃度依賴性的舒張作用。一氧化氮合酶抑制劑L-NAME以及鳥苷酸環化酶抑制劑ODG部分抑制葛根素的舒張作用。在另一組去內皮試驗中, 腺苷酸環化酶抑制劑SQ22536, 鳥苷酸環化酶抑制劑ODG, 大電導鈣離子依賴型鉀通道抑制劑Iberiotoxin以及電壓門控型鉀通道抑制劑4-AP對所有藥物的舒張作用沒有影響。然而, ATP型鉀通道抑制劑格列本脲能夠抑制丹參葛根複方,丹參,葛根,丹參素,葛根素,大豆苷以及大豆苷元的最大舒張反應。內向整流型鉀通道抑制劑氯化鋇則降低丹參酚酸B和大豆苷元的最大反應值。非選擇性鉀通道抑制劑乙基氯化銨以及所有鉀通道抑制劑的混合物顯著抑制上述所有藥物的舒張作用。除了葛根素之外,所有的藥物動度依賴性的抑制氯化鈣所引起的血管收縮。 / 體內研究發現大鼠經歷10分鐘雙側頸總動脈夾閉合並低血壓,及24小時的複灌後,與假手術組動物相比,腦血流量顯著降低,氧化性損傷明顯可見。連續7天口服丹參葛根複方(0.3g/kg 和 3g/kg), 丹參 (3g/kg),或者葛根 (3g/kg)對血壓沒有影響。但是,高劑量的丹參葛根複方 (3g/kg) 能夠提高超氧化物歧化酶和過氧化氫酶的活性,抑制丙二醛和一氧化氮的產生。3g/kg的葛根可以提高超氧化物歧化酶的活性,3g/kg的丹參則能抑制一氧化氮的產生。在大鼠中動脈阻塞模型中,連續7天口服丹參葛根複方(3g/kg)能明顯降低腦部的梗死率,同時改善大鼠的神經行為學。 / 總體來說,研究發現丹參葛根複方,丹參,葛根,丹參酚酸B,大豆苷以及大豆苷元的血管舒張作用是通過開平滑肌細胞的通鉀離子通道以及抑制鈣離子內流而實現的。然而葛根素的血管舒張作用是內皮依賴性的,通過產生一氧化氮,開放平滑肌細胞的鉀離子通道而實現的。丹參葛根複方能起到一定的腦保護作用。總而言之,研究表明上述藥物可能會對阻塞性腦血管病的人群有益處。 / Danshen and gegen are used in traditional Chinese medicine for the treatment of cardiovascular diseases. In this study, the relaxant actions of a danshen and gegen formulation (DG; ratio 7:3) and its constituents were investigated on rat-isolated cerebral basilar artery. In addition, the neuroprotective effect of DG was explored in rats subjected to global and focal ischaemia. / DG and all its constituents produced concentration-dependent relaxation of the artery rings precontracted by U46619. Removal of the endothelium had no effect on their vasodilator actions except the maximum response (I[subscript max]) to puerarin was inhibited by 42%. The nitric oxide synthase (NOS) inhibitor L-NAME and guanylyl cyclase (GC) inhibitor ODQ but not the cyclo-oxygenase (COX) inhibitor flurbiprofen produced partial inhibition on the puerarin-induced effect. In a set of endothelium-denuded artery rings, adenylyl cyclase (AC) inhibitor SQ22536, GC inhibitor ODQ, KV channel inhibitor 4-aminopyridine (4-AP) and BK[subscript Ca) channel inhibitor iberiotoxin had no influence on their vasodilator actions. However, pretreatment with K[subscript ATP] channel inhibitor glibenclamide reduced Imax to DG, danshen, gegen, danshensu, puerarin, daidzein and daidzin. K[subscript IR] inhibitor barium chloride (BaCl₂) reduced II[subscript max] to salvianolic acid B and daidzein. The non-selective K⁺ channel inhibitor tetraethylammonium (TEA), or a combination of all the K⁺ channel inhibitors produced significant partial inhibitions on all the agents’ actions. Electrophysiological studies on smooth muscle cells isolated from rat basilar artery also confirmed that DG, danshen, gegen danshensu, puerarin, daidzein and daidzin elevated K[subscript ATP] currents. In addition, DG and all its constituents, except puerarin, produced concentration-dependent inhibition on CaCl₂-induced vasoconstrictions. These findings were confirmed by con-focal microscopy studies. / In vivo study on a rat model of global ischaemia showed that challenging the rats with 10 min bilateral common carotid artery occlusion combined with hypotension, and followed by 24 h reperfusion produced significant decrease in cerebral blood flow and oxidative damage compared to sham-operated animals. Administration of DG (0.3 g/kg and 3 g/kg, p.o.), danshen (3 g/kg, p.o.) or gegen (3 g/kg, p.o.) for 7 days had no effect on blood pressure. However, the 7 days treatment with DG (3 g/kg) restored superoxide dismutase (SOD) and catalase (CAT) activities, suppressed the production of maleic dialdehyde (MDA), and inhibited the production of nitric oxide (NO). In addition, gegen (3 g/kg) restored SOD enzyme activity, whereas, danshen (3 g/kg) inhibited NO production. In addition, treatment with DG (3 g/kg) showed a significant reduction in infarct weight and improved the neurological deficit in a rat model of focal cerebral ischaemia induced by middle cerebral artery occlusion (MCAO). / In conclusion, the vasorelaxant actions of DG, danshen, gegen, salvianolic acid B, danshensu, daidzein and daidzin were found to involve the opening of K⁺ channels and inhibition of Ca²⁺ influx in the vascular smooth muscle cells. In contrast, puerarin produced vasodilatation via an endothelium-dependent mechanism involving NO production and an endothelium-independent pathway mediated by the opening of K⁺ channels. DG may have some cerebro-protective effects. Overall, the present studies showed that DG and its constituents could be beneficial to patients with obstructive cerebrovascular diseases. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Deng, Yan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 164-178). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / ABSTRACT --- p.v / 摘要 --- p.iviii / ACKNOWLEDGEMENTS --- p.x / PUBLICATIONS BASED ON THIS THESIS --- p.xii / ABBREVIATIONS --- p.xiv / Chapter CHAPTER 1 --- Introduction --- p.1 / Chapter 1.1 --- Chinese Medicines in treatment of cerebrovascular diseases --- p.2 / Chapter 1.2 --- Danshen --- p.4 / Chapter 1.2.1 --- Chemical constituents --- p.4 / Chapter 1.2.1.1 --- Hydrophilic compounds of danshen --- p.4 / Chapter 1.2.1.2 --- Lipophilic compounds of danshen --- p.5 / Chapter 1.2.1.3 --- Other compounds --- p.5 / Chapter 1.2.2 --- Pharmacological activities --- p.5 / Chapter 1.2.2.1 --- Vascular protection --- p.5 / Chapter 1.2.2.2 --- Anti-tumour --- p.7 / Chapter 1.2.2.3 --- Treatment of liver diseases --- p.8 / Chapter 1.2.2.4 --- Treatment of drug addiction --- p.9 / Chapter 1.2.2.5 --- Treatment of kidney diseases --- p.10 / Chapter 1.2.3 --- Pharmacokinetics --- p.10 / Chapter 1.3 --- Gegen --- p.12 / Chapter 1.3.1 --- Chemical constituents --- p.12 / Chapter 1.3.2 --- Pharmacology --- p.13 / Chapter 1.3.2.1 --- Vascular effects --- p.13 / Chapter 1.3.2.2 --- Anti-diabetes --- p.14 / Chapter 1.3.2.3 --- Anti-hypercholesterolaemia --- p.15 / Chapter 1.3.2.4 --- Anti-inflammation --- p.16 / Chapter 1.3.2.5 --- Anti-platelet aggregation --- p.17 / Chapter 1.3.3 --- Pharmacokinetics --- p.17 / Chapter 1.4 --- Danshen and gegen formulation --- p.19 / Chapter 1.5 --- Mechanisms of vasodilatation --- p.22 / Chapter 1.5.1 --- Endothelium derived relaxant factors (EDRFs) --- p.22 / Chapter 1.5.1.1 --- Nitric oxide (NO) --- p.22 / Chapter 1.5.1.2 --- Prostacyclin (PGI₂) --- p.23 / Chapter 1.5.1.3 --- Endothelium-derived hyperpolarizating factors (EDHFs)- --- p.23 / Chapter 1.5.2 --- Signal transduction pathways --- p.24 / Chapter 1.5.2.1 --- Guanylyl cyclase-cGMP pathway --- p.24 / Chapter 1.5.2.2 --- Adenylyl cyclase-cAMP pathway --- p.24 / Chapter 1.5.3 --- Ion channels --- p.25 / Chapter 1.5.3.1 --- Potassium channels (K⁺ channels) --- p.25 / Chapter 1.5.3.2 --- Calcium channel (Ca²⁺ channels) --- p.25 / Chapter 1.6 --- Aims of study --- p.27 / Chapter CHAPTER 2 --- Materials and method --- p.28 / Chapter 2.1 --- Herbal preparation --- p.28 / Chapter 2.1.1 --- DG, danshen and gegen preparation --- p.28 / Chapter 2.1.2 --- Identification and quantification of chemical markers in DG water extract --- p.29 / Chapter 2.2 --- Experiments on rat basilar artery --- p.30 / Chapter 2.2.1 --- Animals --- p.30 / Chapter 2.2.2 --- Chemicals --- p.30 / Chapter 2.2.3 --- Isolation and mounting of blood vessels --- p.33 / Chapter 2.2.4 --- Protocols --- p.34 / Chapter 2.2.4.1 --- Effects on U46619-precontracted tone --- p.34 / Chapter 2.2.4.2 --- Endothelium-dependent mechanism --- p.34 / Chapter 2.2.4.3 --- Endothelium-independent mechanism --- p.35 / Chapter 2.2.4.4 --- Calcium channels --- p.36 / Chapter 2.2.4.5 --- Positive control --- p.36 / Chapter 2.2.5 --- Statistical analysis --- p.37 / Chapter 2.3 --- Experiments on rat cerebral basilar artery smooth muscle cells K[subscript ATP] channals --- p.38 / Chapter 2.3.1 --- Animals --- p.38 / Chapter 2.3.2 --- Chemicals --- p.38 / Chapter 2.3.3 --- Isolation of rat cerebral vascular smooth muscle cells --- p.40 / Chapter 2.3.4 --- Whole cell patch-clamp electrophysiology --- p.40 / Chapter 2.3.5 --- Statistical analysis --- p.44 / Chapter 2.4 --- Experiments on rat cerebral basilar artery smooth muscle cells calcium channels --- p.45 / Chapter 2.4.1 --- Animals --- p.45 / Chapter 2.4.2 --- Chemicals --- p.45 / Chapter 2.4.3 --- Isolation of rat cerebral vascular smooth muscle cells --- p.47 / Chapter 2.4.4 --- Dye loading and determination of [Ca²⁺]i --- p.47 / Chapter 2.4.5 --- Statistical analysis --- p.48 / Chapter 2.5 --- In vivo study of global ischaemia --- p.49 / Chapter 2.5.1 --- Animals --- p.49 / Chapter 2.5.2 --- Drugs and chemicals --- p.49 / Chapter 2.5.3 --- Experimental protocols for global ischaemia --- p.49 / Chapter 2.5.4 --- Induction of global ischaemia --- p.50 / Chapter 2.5.5 --- Blood pressure measurement --- p.52 / Chapter 2.5.6 --- Measurement of cerebral blood flow --- p.52 / Chapter 2.5.7 --- Biochemical assessment --- p.53 / Chapter 2.5.7.1. --- Dissection and homogenization --- p.53 / Chapter 2.5.7.2. --- Measurement of malondialdehyde (MDA) --- p.53 / Chapter 2.5.7.3. --- Estimation of nitrite --- p.53 / Chapter 2.5.7.4 --- Superoxide dismutase activity (SOD) --- p.54 / Chapter 2.5.7.5 --- Reduced glutathione (GSH) --- p.54 / Chapter 2.5.7.6 --- Catalase (CAT) --- p.55 / Chapter 2.5.7.7 --- NOS activity --- p.55 / Chapter 2.5.7.8 --- Protein --- p.56 / Chapter 2.5.8 --- Statistical analysis --- p.56 / Chapter 2.6 --- In vivo study of focal ischaemia --- p.57 / Chapter 2.6.1 --- Animals --- p.57 / Chapter 2.6.2 --- Drugs and chemicals --- p.57 / Chapter 2.6.3 --- Experimental protocols for global ischaemia --- p.57 / Chapter 2.6.4 --- Focal cerebral ischaemia-reperfusion model --- p.57 / Chapter 2.6.5 --- Assessment of neurobehavioural changes --- p.59 / Chapter 2.6.6 --- Assessment of cerebral infarction --- p.60 / Chapter 2.6.7 --- Statistical analysis --- p.60 / Chapter CHAPTER 3 --- Results --- p.61 / Chapter 3.1 --- Identification and quantification of chemical markers in DG water extract --- p.61 / Chapter 3.2 --- Effects of DG and its constituents on rat cerebral basilar artery --- p.64 / Chapter 3.2.1 --- Investigations on endothelium-dependent mechanisms --- p.64 / Chapter 3.2.2 --- Investigations on endothelium-independent mechanisms --- p.68 / Chapter 3.2.3 --- Positive control --- p.86 / Chapter 3.2.3 --- Investigations on calcium channels --- p.88 / Chapter 3.3 --- Effects of DG and its constituents on rat cerebral basilar artery smooth muscle cells --- p.91 / Chapter 3.3.1 --- Effects of water crude-extracts of DG, danshen, and gegen on K[subscript ATP] channels --- p.91 / Chapter 3.3.2 --- Effects of active constituents of danshen hydrophilic fraction on K[subscript ATP] channels --- p.100 / Chapter 3.3.3 --- Effects of the major isoflavonoids of gegen on K[subscript ATP] channels --- p.105 / Chapter 3.4 --- Effects of DG and its constituents on calcium channels of basilar artery smooth muscle cells --- p.112 / Chapter 3.5 --- Effects of DG, danshen and gegen on rat global ischaemia --- p.117 / Chapter 3.5.1 --- Effects of DG, danshen and gegen on rats’ blood pressure and cerebral blood flow --- p.117 / Chapter 3.5.2 --- Effects of DG, danshen and gegen on lipid peroxidation --- p.120 / Chapter 3.5.3 --- Effects of DG, danshen and gegen on SOD activity --- p.120 / Chapter 3.5.4 --- Effects of DG, danshen and gegen on CAT activity --- p.120 / Chapter 3.5.5 --- Effects of DG, danshen and gegen on reduced GSH level --- p.121 / Chapter 3.5.6 --- Effects of DG, danshen and gegen on NOS system --- p.126 / Chapter 3.6 --- Effect of DG on rat focal ischaemia --- p.129 / Chapter 3.6.1 --- Effect of DG on cerebral infarction --- p.129 / Chapter 3.6.2 --- Effect of DG on neurological deficits --- p.129 / Chapter CHAPTER 4 --- Discussion --- p.132 / Chapter 4.1 --- Studies of DG and its constituents on rat cerebral basilar artery --- p.133 / Chapter 4.1.1 --- Constituents of DG on U46619-precontracted tone --- p.133 / Chapter 4.1.2 --- Investigations on endothelium-dependent mechanisms --- p.133 / Chapter 4.1.3 --- Investigations on endothelium-independent mechanisms --- p.136 / Chapter 4.1.4 --- Investigations on calcium channels --- p.139 / Chapter 4.2 --- Effects of DG and its constituents on rat cerebral basilar artery smooth muscle cell K[subscript ATP] channels --- p.143 / Chapter 4.3 --- Effects of DG and its constituents on calcium influx in rat basilar artery smooth muscle cells --- p.147 / Chapter 4.4 --- Effects of DG, danshen and gegen on rat transient global ischaemia --- p.150 / Chapter 4.4.1 --- Effects of DG, danshen and gegen on rats’ blood pressure and cerebral blood flow --- p.150 / Chapter 4.4.2 --- Effects of DG, danshen and gegen on lipid peroxidation, SOD and CAT activity, and GSH level --- p.152 / Chapter 4.4.3 --- Effects of DG, danshen and gegen on NOS system --- p.155 / Chapter 4.5 --- Effects of DG on rat focal ischaemia --- p.157 / Chapter 4.6 --- Further studies --- p.160 / Chapter 4.7 --- Conclusion --- p.162 / REFERENCES --- p.164
186

Comparing the effectiveness of different strategies for primary prevention of cardiovascular diseases through anti-hypertensive drugs. / 降壓藥物進行心臟血管疾病初級預防的不同策略的效果的比較研究 / CUHK electronic theses & dissertations collection / Xiang ya yao wu jin xing xin zang xue guan ji bing chu ji yu fang de bu tong ce lüe de xiao guo de bi jiao yan jiu

January 2010 (has links)
Conclusions: In the same number of people treated, the number of CVD events avoided for the overall risk approach is always larger than that of the blood pressure approach. The additional benefits of overall risk approach compared with the blood pressure approach decreases as the percentage of people from the total population is increased. If the current practice and hypertension guidelines in China are shifted to the overall risk approach, many more CVD events could be avoided with the same resources used. / Methods: The sample used in the analyses includes a subsample of 38,673 persons from the 2002 China National Nutrition and Health Survey, who were 30-74 years old, without previous CVD, and had data on all major CVD risk factors. CVD risks of the patients selected by each approach are predicted using suitable risk prediction equation. The RRR of anti-hypertensive drug treatment derived from meta-analyses of RCTs. The difference in the absolute effectiveness between the two approaches is used to quantify how many more CVD events can be prevented in 1000 people treated by the ORA as compared to the BPA. / Objective: To estimate and compare the number of major cardiovascular events that could be avoided by shifting the blood pressure approach to the overall risk approach if the same percentage of people in a large, representative Chinese population is treated with anti-hypertensive drugs. / Results: When 2.5%, 5.5%, 10.1%, 15.5%, 20.7%, 25.7% or 33.0% of the 38,673 subjects were treated by anti-hypertensive drugs by using the two approaches respectively, 22 (95%CI: 17&sim;28), 13 (11&sim;16), 9 (8&sim;10), 7 (6&sim;8), 6 (5&sim;7), 5 (4&sim;6), or 4 (3&sim;4) more CVD events could be avoided in every 1000 people treated if the blood pressure approach is shifted to the overall risk approach, which is in general a 15% to 25% increase in CVD events prevented. / Qin, Ying. / Adviser: Jin Ling Tang. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 116-121). / 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.
187

Efeito do treinamento físico na qualidade de vida, capacidade funcional e fatores de risco cardiovascular nos portadores de doença renal crônica em tratamento conservador /

Silva, Viviana Rugolo Oliveira e. January 2013 (has links)
Orientador: Roberto Jorge da Silva Franco / Coorientador: Luis Cuadrado Martin / Banca: Maria Costa Irigoyen / Banca: Daniela Ponce / Resumo: A Doença Renal Crônica (DRC) é um importante problema mundial de saúde pública. A DRC apresenta, dentre os principais sintomas, a fadiga, a fraqueza muscular e a baixa tolerância ao exercício, sintomas que contribuem diretamente para o sedentarismo e a baixa mobilidade, com consequente aumento da morbidade e mortalidade. Pacientes com DRC apresentam pobre qualidade de vida, incidência elevada de doenças cardiovasculares, alta prevalência de inflamação crônica e disfunção endotelial com aumento de rigidez arterial, da massa ventricular esquerda e da concentração sérica de dimetilarginina assimétrica (ADMA). Acredita-se que o condicionamento físico desses pacientes possa atenuar fatores de risco cardiovascular e implicar na melhora da qualidade de vida e da capacidade funcional. Vários trabalhos têm avaliado essa premissa em pacientes em diálise, porém poucos estudos a avaliaram em portadores de DRC em tratamento conservador. Avaliar o impacto do treinamento físico em relação à capacidade funcional, qualidade de vida e fatores de risco cardiovascular não tradicionais em portadores de DRC em tratamento conservador. Ensaio clínico, prospectivo e controlado, não randomizado, composto por 16 portadores de DRC, estágios de II a IV, em tratamento conservador, divididos, de acordo com sua disponibilidade e vontade, em grupo controle (GC) e grupo treinamento (GT). Todos os pacientes foram avaliados inicialmente com a realização de teste ergométrico (protocolo de Bruce) em esteira ergométrica para estratificar a capacidade aeróbica por meio do VO2max estimado. Foi realizado Teste de caminhada de 6 minutos para avaliar aptidão física. Foi avaliada pressão arterial central e parâmetros de rigidez arterial com o aparelho Sphygmocor e realizado Ultrassonografia para a mensuração de diâmetros arteriais e de massa cardíaca. Foram coletados também exames laboratoriais completos para estabelecer o grau de ... / Abstract: Chronic Kidney Disease (CKD) is a worldwide major public health problem. The CKD has among the main symptoms, fatigue, muscle weakness and poor exercise tolerance, symptoms that directly contribute to physical inactivity and low mobility, with consequent increased morbidity and mortality. CKD patients have poor quality of life, increased incidence of cardiovascular diseases, high prevalence of chronic inflammation and endothelial dysfunction with increased arterial stiffness, left ventricular mass and serum concentration of asymmetric dimethylarginine (ADMA). It is believed that the improvement at physical fitness of these patients may attenuate cardiovascular risk factors and result in improved quality of life and functional capacity. Several studies have evaluated this premise in dialysis patients, but few studies have evaluated in CKD patients on conservative treatment. Evaluate the impact of exercise training at functional capacity, quality of life and non-traditional cardiovascular risk factors in CKD patients on conservative treatment. Clinical trial, prospective, controlled and non-randomized study, comprising 16 patients with CKD stages II to IV, undergoing conservative treatment, divided according to their availability and desire in control group (CG) and training group (GT). All patients were evaluated with the Exercise Test (Bruce protocol) at treadmill to stratify aerobic capacity through VO2max. 6-minute walk test was performed to assess physical fitness. We evaluated central blood pressure and arterial stiffness parameters with the device Sphygmocor and used ultrasound for the measurement of arterial diameters and cardiac mass. Laboratory tests were also collected to establish the full extent of renal inflammation and serum concentration of ADMA. Were applied questionnaires to verify quality of life, the SF-36, and to stratification of inactivity, the IPAQ. Patients of GT were included in an exercise program consisting of ... / Mestre
188

Follow-up study of childhood obstructive sleep apnoea syndrome: a cardiovascular perspective.

January 2010 (has links)
Ng, Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves xvi-xlviii). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.i / ABSTRACT / In English --- p.ii / In Chinese --- p.iv / LIST OF TABLES --- p.vi / LIST OF FIGURE --- p.viii / ABBREVIATIONS / For Units --- p.ix / For Prefixes of the International System of Units --- p.ix / For Terms Commonly Used --- p.X / Chapter CHAPTER 1 --- Overview of Childhood Obstructive Sleep Apnoea Syndrome (OSAS) / Chapter 1.1 --- Prevalence --- p.1 / Chapter 1.2 --- Clinical Features --- p.3 / Chapter 1.3 --- Definitions and Cutoffs --- p.4 / Chapter 1.4 --- Pathophysiology --- p.6 / Chapter 1.5 --- Risk Factors / Chapter 1.5.1 --- Gender --- p.8 / Chapter 1.5.2 --- Obesity --- p.9 / Chapter 1.5.3 --- Adenotonsillar Hypertrophy --- p.10 / Chapter 1.5.4 --- Genetic --- p.11 / Chapter 1.5.5 --- Atopic Diseases --- p.12 / Chapter 1.6 --- Complications / Chapter 1.6.1 --- Neurobehavioural Deficits --- p.13 / Chapter 1.6.2 --- Growth Defects --- p.14 / Chapter 1.6.3 --- Metabolic Disorders --- p.16 / Chapter 1.6.4 --- Systemic inflammation --- p.17 / Chapter 1.6.5 --- Cardiovascular Consequences --- p.19 / Chapter 1.7 --- Diagnosis --- p.20 / Chapter 1.8 --- Treatment / Chapter 1.8.1 --- Surgical Treatment --- p.22 / Chapter 1.8.2 --- Continuous Positive Airway Pressure (CPAP) --- p.24 / Chapter 1.8.3 --- Corticosteroids --- p.24 / Chapter 1.8.4 --- Leukotriene Receptor Antagonist --- p.25 / Chapter 1.8.5 --- Oral Appliances --- p.26 / Chapter 1.8.6 --- Weight Control --- p.27 / Chapter CHAPTER 2 --- OSAS and Cardiovascular Complications in Adults / Chapter 2.1 --- Mechanism / Chapter 2.1.1 --- Acute Cardiovascular Responses --- p.28 / Chapter 2.1.2 --- Chronic Cardiovascular Responses --- p.29 / Chapter 2.2 --- Hypertension / Chapter 2.2.1 --- Epidemiological and Clinical Data --- p.31 / Chapter 2.2.2 --- Characteristics --- p.32 / Chapter 2.2.3 --- Mechanisms --- p.33 / Chapter 2.2.4 --- Treatment --- p.34 / Chapter 2.3 --- Heart Failure --- p.35 / Chapter 2.4 --- Stroke --- p.37 / Chapter 2.5 --- Cardiac Arrhythmias --- p.39 / Chapter 2.6 --- Myocardial Ischemia and Vascular Disease --- p.41 / Chapter 2.7 --- Pulmonary Hypertension --- p.43 / Chapter CHAPTER 3 --- OSAS and cardiovascular complication in children / Chapter 3.1 --- Blood Pressure --- p.45 / Chapter 3.2 --- Ventricular Hypertrophy and Dysfunctions --- p.48 / Chapter 3.3 --- Heart Rate Variability --- p.50 / Chapter 3.4 --- Arterial Tone --- p.51 / Chapter 3.5 --- Endothelial Function --- p.51 / Chapter CHAPTER 4 --- Longitudinal follow-up study of children with OSAS - a cardiovascular perspective / Chapter 4.1 --- Introduction --- p.53 / Chapter 4.2 --- Methods / Chapter 4.2.1 --- Subjects and Study Design --- p.57 / Chapter 4.2.2 --- Polysomnography --- p.59 / Chapter 4.2.3 --- Ambulatory Blood Pressure Measurement --- p.61 / Chapter 4.2.4 --- Statistical Analysis --- p.62 / Chapter 4.3 --- Results / Chapter 4.3.1 --- Subject Characteristics --- p.64 / Chapter 4.3.2 --- Blood Pressure During Wakefulness --- p.71 / Chapter 4.3.3 --- Blood Pressure During Sleep --- p.76 / Chapter 4.3.4 --- Nocturnal Blood Pressure Dipping --- p.83 / Chapter 4.3.5 --- Blood Profile --- p.86 / Chapter 4.4 --- Discussion --- p.87 / Chapter 4.5 --- Conclusion --- p.99 / Reference List --- p.xvi
189

Cardiovascular complications of childhood obstructive sleep apnea syndrome.

January 2007 (has links)
Au, Chun Ting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves xxvii-lv). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.i / ABSTRACT / In English --- p.ii / In Chinese --- p.v / LIST OF TABLES --- p.vii / ABBREVIATIONS / For Units --- p.ix / For Prefixes of the international system of units --- p.ix / For Terms commonly used in the report --- p.x / STATEMENT OF WORK DONE --- p.xvi / Chapter CHAPTER 1 --- Overview of Childhood Obstructive Sleep Apnea Syndrome (OSAS) / Chapter 1.1. --- Clinical Features of Childhood OSAS --- p.1 / Chapter 1.2. --- Definition of Childhood OSAS --- p.2 / Chapter 1.3. --- Prevalence of Childhood OSAS --- p.3 / Chapter 1.4. --- Pathophysiology --- p.4 / Chapter 1.5. --- Risk Factors --- p.6 / Chapter 1.6. --- Diagnosis --- p.10 / Chapter 1.7. --- Treatment / Chapter 1.7.1. --- Tonsillectomy and Adenoidectomy (T&A) --- p.12 / Chapter 1.7.2. --- Continuous Positive Airway Pressure (CPAP) --- p.14 / Chapter 1.7.3. --- Corticosteroids --- p.15 / Chapter 1.7.4. --- Leukotriene Receptor Antagonist --- p.16 / Chapter 1.8. --- Complications of Childhood OSAS / Chapter 1.8.1. --- Growth Failure --- p.17 / Chapter 1.8.2. --- Neurocognitive Abnormalities --- p.19 / Chapter 1.8.3. --- Cardiovascular Abnormalities --- p.20 / Chapter CHAPTER 2 --- Cardiovascular Complications of OSAS in Adults (Literature Review) / Chapter 2.1. --- Acute Effects of OSAS on Cardiovascular System --- p.21 / Chapter 2.2. --- Chronic Effects of OSAS on Cardiovascular System --- p.23 / Chapter 2.3. --- Hypertension --- p.24 / Chapter 2.4. --- Heart Failure --- p.28 / Chapter 2.5. --- Pulmonary Hypertension --- p.30 / Chapter 2.6. --- Arrhythmias --- p.31 / Chapter 2.7. --- Cardiac Ischemia and Vascular Disease --- p.33 / Chapter 2.8. --- Stroke --- p.34 / Chapter CHAPTER 3 --- Cardiovascular Complications of Childhood OSAS (Literature Review) / Chapter 3.1. --- Blood Pressure --- p.37 / Chapter 3.2. --- Ventricular Structure and Function --- p.40 / Chapter 3.3. --- Arterial Distensibility --- p.42 / Chapter 3.4. --- Heart Rate Variability --- p.42 / Chapter CHAPTER 4 --- Ambulatory Blood Pressure in Children with OSAS / Chapter 4.1. --- Introduction --- p.44 / Chapter 4.2. --- Methods / Chapter 4.2.1. --- Subjects and Study Design --- p.46 / Chapter 4.2.2. --- Polysomnography (PSG) --- p.47 / Chapter 4.2.3. --- Ambulatory Blood Pressure Measurement (ABPM) --- p.49 / Chapter 4.2.4. --- Statistical Analysis --- p.50 / Chapter 4.3. --- Results / Chapter 4.3.1. --- Subject Characteristics --- p.52 / Chapter 4.3.2. --- Blood Pressure during Wakefulness --- p.55 / Chapter 4.3.3. --- Blood Pressure during Sleep --- p.57 / Chapter 4.4. --- Discussion --- p.62 / Chapter 4.5. --- Conclusion --- p.70 / Chapter CHAPTER 5 --- Cardiac Remodeling and Dysfunction in Children with OSAS / Chapter 5.1. --- Introduction --- p.71 / Chapter 5.2. --- Methods / Chapter 5.2.1. --- Subjects and Study Design --- p.72 / Chapter 5.2.2. --- Polysomnography (PSG) --- p.74 / Chapter 5.2.3. --- Conventional Echocardiography --- p.75 / Chapter 5.2.4. --- Tissue Doppler Imaging --- p.76 / Chapter 5.2.5. --- Statistical Analysis --- p.77 / Chapter 5.3. --- Results / Chapter 5.3.1. --- Study Population --- p.79 / Chapter 5.3.2. --- Polysomnographic Findings --- p.79 / Chapter 5.3.3. --- Echocardiographic Findings / Chapter 5.3.3.1. --- Right Ventricle --- p.81 / Chapter 5.3.3.2. --- Left Ventricle --- p.83 / Chapter 5.3.4. --- Treatment Effect --- p.86 / Chapter 5.4. --- Discussion --- p.90 / Chapter 5.5. --- Conclusion --- p.95 / Chapter CHAPTER 6 --- Conclusion --- p.96 / APPENDIX I Hong Kong Children Sleep Questionnaire (Chinese) --- p.xvii / APPENDIX II Hong Kong Children Sleep Questionnaire (English) --- p.xxii / REFERENCES --- p.xxvii
190

A new strategy to determine whose cholesterol to measure for primary prevention of cardiovascular disease: a modelling study using UK and Chinese data. / 設計並評估一個新的心血管初級預防中使用的膽固醇篩查模型: 中英代表性人群模型研究 / She ji bing ping gu yi ge xin de xin xue guan chu ji yu fang zhong shi yong de dan gu chun shai cha mo xing: Zhong Ying dai biao xing ren qun mo xing yan jiu

January 2012 (has links)
目的:針對心血管初級預防,世界各國均推薦某一年齡段人群全部測量膽固醇以估算心血管病發病風險。此舉耗費高且非必須,本研究旨在建立並驗證一個新型的选择性膽固醇篩查模型,用以篩查需藥物治療之高危人群,并在成本效益方面與其它篩查模型相比較。 / 方法:本模型具體采用兩步法:首先利用一個足夠高的假設膽固醇值代入心血管病風險預測方程,用以系統性的高估絶大多數人的心血管病風險;其次只有假設心血管病風險高於推薦治療閾值時,該個體才需要測量膽固醇,並進行實際心血管病風險分析。 / 英国健康调查和中国营养与健康调查是本次研究的合适数据。我們首先探索最優的假設膽固醇值,尋找到最後膽固醇值之後,我們將繼續測試我們的新型膽固醇篩查模型,在不同的治療閾值下,表現是否穩定。我們以靈敏度,特異度和徐篩查人群為指標,比較我們模型與全民篩查模型和英國NICE 選擇篩查模型相比較。之後我們估算在中英人群中應用該篩查模型,所需耗費的成本和可預防心血管事件數。 / 结果:與全名篩查模型相比,我們的模型靈敏度相若但可以節省80%左右的篩查費用。模型的靈敏度主要取決於所採用的假設膽固醇值,與所用風險預測方程,治療閾值和人群心血管風險分佈無關。當以均數加2 倍標準差作為假設膽固醇值時,靈敏度可達到97.5%左右,特異度可以達到90%左右,符合預期。模型應用於中國人群得到的結果類似。值得註意的是,在中國人群中,即使不測量膽固醇,模型靈敏度亦接近95%。此外,將膽固醇篩查項目限制于男性50-84歲,女性60-84 歲年齡段可以進一步減少篩檢費用。在人群影響方面,我們模型可預防心血管事件數比全名篩查模型略少,但成本大大降低。英國NICE 模型適用於某些特定情況,但並非全部。 / 結論:我們的新型篩查模型靈敏度與全民篩查模型相若,但可以節省大量篩查費用。在资源匮乏地区,可考虑在某一特定年龄段运用我们的模型已达到进一步减少费用的效果。如果本研究结果得到进一步数据证实,對於中國人群而言,膽固醇測量可能並非心血管風險評估所必須。 / Objectives / Since the mid 1990s, most guidelines on primary prevention of cardiovascular disease (CVD) have recommended regular cholesterol measurement for all adults or those above a certain age (which is known as mass screening). Cholesterol measurement comprises a large cost of CVD prevention and is not necessarily required in those who do not need drug intervention. In order to reduce this cost, we have developed a new selective cholesterol screening model in order to determine whose cholesterol should be measured for drug prevention. The model was evaluated and compared with other widely adopted models in basic model performance as well as cost effectiveness. / Methods / The new model has two steps. In the first step, we purposely over-estimated the majority of respondents’ CVD risk by substituting a sufficiently high hypothetical cholesterol value in the risk estimation. We then recommend cholesterol measurement only to those with the estimated CVD risk above a predetermined risk threshold for drug treatment. In the second step, the CVD risk is re-estimated based on the individual’s real cholesterol consentration. Those with a risk above the treatment threshold are recommended for drug treatment. / We evaluated the performance of our two-step model with data from the Health Survey for England and re-evaluated it with data from the China Nutrition and Health Survey 2002. By varying the hypothetical cholesterol values and treatment thresholds in CVD risk, we assessed the sensitivity, specificity and proportion of the population who need to measure cholesterol and compared it with the US mass screening model and the UK NICE selective screening model. We further compared the costs and CVD events avoided in the compared screening programmes. We also examined how the age restriction should be set in cholesterol screening programmes. / Results / As compared to mass screening, our new model can achieve a high sensitivity and save some 80% the cost of cholesterol measurements. The sensitivity depends mainly on the hypothetical cholesterol level used and seems independent of population’s CVD risk, treatment cut-off values and risk prediction model. The model performed well in almost all the conditions tested. When the hypothetical cholesterol was set at MEAN+2SD, the resulting sensitivity of our selective screening model was almost always above 95% and close to the expected 97.5%. The sensitivity was only compromised slightly if cholesterol is not measured at all for the Chinese population. Furthermore, in order to save more costs, cholesterol measurement could be better restricted to men aged 50-84 and women 60-84 years regardless of the screening model used. In CVD events prevented, mass screening is always the best but our model can prevent almost as many. In costs, mass screening is always the most expensive but our model can save all or most of the cost. The NICE selective model can perform as well as our model only when it is used in an appropriate manner and in certain circumstances. / Conclusion / Our new cholesterol screening model has a high sensitivity which is comparable to that of universal screening programs but can save most of the cost on cholesterol measurements. In where resources are particular sparse, our model can also perform well by applying it only to certain age groups, which will further save cholesterol measurement costs. Cholesterol measurement could even be completely avoided for the Chinese population if our findings can be re-confirmed correct with more updated data. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Hu, Xuefeng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 114-121). / Abstract also in Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgements --- p.vi / Abbreviations used in the thesis --- p.viii / List of Tables --- p.xvi / List of Figures --- p.xviii / List of Boxes --- p.xix / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The burden of cardiovascular disease --- p.1 / Chapter 1.2 --- Primary prevention of CVD --- p.2 / Chapter 1.3 --- The high-risk individual strategy for CVD primary prevention --- p.3 / Chapter 1.3.1 --- The high risk individual strategy is effective --- p.4 / Chapter 1.3.2 --- The high risk individual strategy is cost-effective --- p.4 / Chapter 1.4 --- Who should be treated with drugs? --- p.5 / Chapter 1.4.1 --- The single risk factor strategy --- p.5 / Chapter 1.4.2 --- The overall CVD risk strategy --- p.7 / Chapter 1.4.3 --- Scope of CVD primary prevention --- p.8 / Chapter 1.5 --- Methods for assessing the CVD risk --- p.9 / Chapter 1.6 --- Current strategies for cholesterol measurements --- p.10 / Chapter 1.6.1 --- United States National Cholesterol Education Program --- p.13 / Chapter 1.6.2 --- American Heart Association CVD and Stroke prevention guideline --- p.14 / Chapter 1.6.3 --- The U.S. Preventive Services Task Force guideline --- p.15 / Chapter 1.6.4 --- New Zealand guideline 2003 --- p.16 / Chapter 1.6.5 --- Australian guideline 2009 --- p.17 / Chapter 1.6.6 --- The Joint British Society guideline-2 --- p.17 / Chapter 1.6.7 --- UK Department of Health guideline on vascular check --- p.18 / Chapter 1.6.8 --- China Blood Lipid Modification Guideline 2007 --- p.18 / Chapter 1.6.9 --- Summary of the reviewed guidelines --- p.19 / Chapter 1.7 --- Rationale for a selective screening model --- p.20 / Chapter 1.8 --- The UK NICE model --- p.22 / Chapter 1.9 --- Objectives of this study --- p.24 / Chapter 2 --- Methods --- p.25 / Chapter 2.1 --- The new cholesterol screening model --- p.25 / Chapter 2.2 --- Framework for evaluating the new screening model --- p.27 / Chapter 2.3 --- Indexes for evaluating the basic performance of screening models --- p.28 / Chapter 2.3.1 --- Sensitivity, specificity and % need cholesterol measurement --- p.28 / Chapter 2.3.2 --- Sensitivity analysis for model performance --- p.29 / Chapter 2.3.2.1 --- Using different hypothetical cholesterol values --- p.29 / Chapter 2.3.2.2 --- Using different treatment cut-off thresholds --- p.30 / Chapter 2.3.2.3 --- Using different populations --- p.30 / Chapter 2.3.2.4 --- Using different risk equations --- p.31 / Chapter 2.4 --- Data --- p.31 / Chapter 2.4.1 --- The Health Survey for England --- p.31 / Chapter 2.4.1.1 --- Background and aim of the survey --- p.31 / Chapter 2.4.1.2 --- Survey design --- p.32 / Chapter 2.4.1.2.1 --- Sampling Frame --- p.32 / Chapter 2.4.1.2.2 --- Weighting variables --- p.33 / Chapter 2.4.1.3 --- Data collection --- p.33 / Chapter 2.4.1.3.1 --- Blood cholesterol --- p.34 / Chapter 2.4.1.3.2 --- Blood pressure --- p.34 / Chapter 2.4.1.3.3 --- Smoking --- p.34 / Chapter 2.4.1.3.4 --- History of CVD and diabetes --- p.34 / Chapter 2.4.1.3.5 --- Treatment history --- p.35 / Chapter 2.4.2 --- The 2002 China National Nutrition and Health Survey --- p.35 / Chapter 2.4.2.1 --- Survey design --- p.36 / Chapter 2.4.2.2 --- Data collection --- p.36 / Chapter 2.4.2.2.1 --- Blood pressure --- p.36 / Chapter 2.4.2.2.2 --- Blood cholesterol --- p.38 / Chapter 2.4.2.2.3 --- Smoking --- p.38 / Chapter 2.4.2.2.4 --- History of CVD, diabetes and drug treatment --- p.38 / Chapter 2.4.3 --- Subjects eligible for analysis in this study --- p.38 / Chapter 2.5 --- CVD risk prediction --- p.43 / Chapter 2.5.1 --- The Framingham risk equation for the UK population --- p.43 / Chapter 2.5.2 --- The Asian equation for the Chinese population --- p.44 / Chapter 2.5.3 --- Adjusting for cholesterol and blood pressure --- p.45 / Chapter 2.5.4 --- Deriving the hypothetical cholesterol --- p.46 / Chapter 2.6 --- Identifying the appropriate age ranges for cholesterol measurement --- p.47 / Chapter 2.7 --- Comparing various screening models and options --- p.47 / Chapter 2.7.1 --- Compared screening models and options --- p.47 / Chapter 2.7.1 --- Indices for the performance of the screening options --- p.49 / Chapter 2.7.2 --- Costs of different screening options --- p.50 / Chapter 2.7.2.1 --- Components of screening cost from societal perspective --- p.50 / Chapter 2.7.2.1.1 --- Cost for inviting people for data collection --- p.50 / Chapter 2.7.2.1.2 --- Cost for the full risk assessment --- p.51 / Chapter 2.7.2.1.3 --- Treatment cost --- p.51 / Chapter 2.7.2.1.4 --- Cost saved for avoided CVD events --- p.52 / Chapter 2.7.2.2 --- Components of screening cost from health system’s perspective --- p.52 / Chapter 2.7.3 --- Number of CVD events avoidable --- p.53 / Chapter 2.8 --- Statistical analysis --- p.54 / Chapter 2.8.1 --- Descriptive analysis --- p.54 / Chapter 2.8.2 --- Cross-tabulation analysis --- p.54 / Chapter 2.8.3 --- Survey data analysis --- p.54 / Chapter 3 --- Results --- p.57 / Chapter 3.1 --- Description of data --- p.57 / Chapter 3.1.1 --- The UK population --- p.57 / Chapter 3.1.1.1 --- Sumamry of CVD risk and risk factors --- p.57 / Chapter 3.1.1.2 --- Distribution of age --- p.57 / Chapter 3.1.1.3 --- Distribution of blood pressure and blood cholesterol --- p.58 / Chapter 3.1.1.4 --- Distribution of the predicted 10-year CVD risk --- p.62 / Chapter 3.1.1.5 --- Relation between the risk threshold and age --- p.63 / Chapter 3.1.2 --- The Chinese population --- p.65 / Chapter 3.1.2.1 --- Summary of CVD risk and risk factors --- p.65 / Chapter 3.1.2.2 --- Distribution of age --- p.65 / Chapter 3.1.2.3 --- Distribution of blood pressure and blood cholesterol --- p.66 / Chapter 3.1.2.4 --- Distribution of the predicted 10-year CVD risk --- p.69 / Chapter 3.1.2.5 --- Relation between the risk threshold and age --- p.70 / Chapter 3.2 --- Performance of our new screening model --- p.72 / Chapter 3.2.1 --- Performance according to cholesterol values in the UK population --- p.72 / Chapter 3.2.2 --- Performance according to treatment cut-offs in the UK population --- p.73 / Chapter 3.2.3 --- Performance according to cholesterol values in the Chinese population --- p.73 / Chapter 3.2.4 --- Performance according to the risk cut-offs in the Chinese population --- p.74 / Chapter 3.2.4 --- Performance using different risk equations --- p.76 / Chapter 3.3 --- Comparison with other existing screening models --- p.77 / Chapter 3.3.1 --- Performance of the 3 models within an age-restricted UK population --- p.79 / Chapter 3.3.2 --- Performance of the 3 models within an age-restricted Chinese population --- p.81 / Chapter 3.3.3 --- Performance of the 3 models in the entire UK population --- p.83 / Chapter 3.3.4 --- Performance of the 3 models in the entire Chinese population --- p.84 / Chapter 3.3.5 --- Costs of various screening options --- p.87 / Chapter 3.3.6 --- Number of CVD events avoidable of the screening programmes --- p.92 / Chapter 4 --- Discussion --- p.96 / Chapter 4.1.1 --- Performance at different hypothetical cholesterol values --- p.96 / Chapter 4.1.2 --- Performance at various treatment cut-off thresholds --- p.97 / Chapter 4.1.3 --- Performance with different risk equations --- p.98 / Chapter 4.1.4 --- Performance in different populations --- p.99 / Chapter 4.1.5 --- Performance with different survival functions --- p.99 / Chapter 4.2 --- Further modifications of the model --- p.100 / Chapter 4.2.1 --- A model without any cholesterol measurement --- p.100 / Chapter 4.2.2 --- Age restriction for selective models --- p.102 / Chapter 4.2.3 --- Our model with potential personalized treatment cut-off --- p.103 / Chapter 4.2.4 --- Three key things to ensure model performance in other population --- p.104 / Chapter 4.3 --- CVD events preventable --- p.105 / Chapter 4.3.1 --- Importance of age restriction --- p.105 / Chapter 4.3.2 --- Limitations of the NICE model --- p.106 / Chapter 4.4 --- Costs of different screening models --- p.107 / Chapter 4.4.1 --- Cost from different perspectives --- p.107 / Chapter 4.4.2 --- Cholesterol measurement cost and routine data collection --- p.108 / Chapter 4.4.3 --- Cost components --- p.109 / Chapter 4.4.4 --- Ways to reduce cholesterol measurement costs --- p.109 / Chapter 4.4.5 --- Costs and gain of the missing 2.5% high risk individuals --- p.109 / Chapter 4.5 --- Strengths and limitations of this study --- p.110 / Chapter 4.6 --- Recommendations --- p.113 / References --- p.114

Page generated in 0.1064 seconds