Ma, Yan. / "Ca" in the title is subscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 143-166). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Dong Yingying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 99-125). / Abstracts in English and Chinese. / Declaration --- p.i / Acknowledgement --- p.ii / Publication list --- p.iii / Abstract (English) --- p.ix / Abstract (Chinese) --- p.xii / Abbreviations --- p.xiv / List of figures / tables --- p.xvi / Chapter Chapter 1. --- General Introduction / Chapter 1.1 --- The role of endothelium in regulating vascular tone --- p.1 / Chapter 1.1.1 --- Nitric oxide (NO) --- p.2 / Chapter 1.1.2 --- Endothelium-derived hyperpolarizing factor (EDHF) --- p.7 / Chapter 1.1.3 --- Prostacyclin (PGI2) --- p.20 / Chapter 1.2 --- EDHF-mediated endothelial function in coronary circulation --- p.22 / Chapter 1.2.1 --- Role of EDHF in coronary microarteries --- p.23 / Chapter 1.2.2 --- Role of EDHF in cardiac veins --- p.24 / Chapter 1.3 --- Effect of ischemia-reperfusion on endothelial function in coronary circulation --- p.25 / Chapter 1.3.1 --- Ischemia-reperfusion injury --- p.26 / Chapter 1.3.2 --- Effect of ischemia-reperfusion on endothelial function in coronary microarteries --- p.28 / Chapter 1.3.3 --- Effect of ischemia-reperfusion on endothelial function in cardiac veins --- p.29 / Chapter 1.4 --- Alteration of endothelial function during cardiac surgery / Chapter 1.4.1 --- Cardioplegia and organ preservation solutions --- p.31 / Chapter 1.4.2 --- Combined effects of hypoxia-reoxygenation and ST solution on endothelial function in coronary microarteries/cardiac veins --- p.34 / Chapter 1.4.3 --- Effect of nicorandil on endothelial function --- p.34 / Chapter Chapter 2. --- Materials and Methods --- p.37 / Chapter 2.1 --- Isometric force study in micro arteries/veins --- p.37 / Chapter 2.1.1 --- Preparation of vessels --- p.37 / Chapter 2.1.1.1 --- Preparation of porcine coronary microarteries --- p.37 / Chapter 2.1.1.2 --- Preparation of porcine cardiac veins --- p.37 / Chapter 2.1.2 --- Technique of setting up --- p.39 / Chapter 2.1.2.1 --- Mounting of microvessels --- p.39 / Chapter 2.1.2.2 --- Normalization procedure for microvessels --- p.39 / Chapter 2.1.3 --- EDHF-mediated vasorelaxation --- p.40 / Chapter 2.1.3.1 --- Precontraction and stimuli of EDHF --- p.40 / Chapter 2.1.3.2. --- “Truéحresponse of EDHF --- p.40 / Chapter 2.1.4 --- Data acquisition and analysis --- p.41 / Chapter 2.2 --- Hypoxia and reoxygenation --- p.41 / Chapter 2.2.1 --- Calibration of 02-special electrode --- p.41 / Chapter 2.2.2 --- Measurement of --- p.02 / Chapter 2.3 --- Statistical analysis --- p.42 / Chapter 2.4 --- Chemicals --- p.43 / Chapter Chapter 3. --- Hypoxia-Reoxygenation in Coronary Microarteries: Combined Effect with St Thomas Cardioplegia and Temperature on the Endothelium- derived Hyperpolarizing Factor and Protective Effect of Nicorandil --- p.44 / Chapter 3.1 --- Abstract --- p.44 / Chapter 3.2 --- Introduction --- p.45 / Chapter 3.3 --- Experimental design and analysis --- p.47 / Chapter 3.3.1 --- Vessel Preparation --- p.47 / Chapter 3.3.2 --- Normalization --- p.48 / Chapter 3.3.3 --- Hypoxia --- p.48 / Chapter 3.3.4 --- Effect of H-R on EDHF-mediated relaxation in coronary microarteries --- p.49 / Chapter 3.3.5 --- Combined effects ofH-R and ST solution on EDHF-mediated relaxation in coronary microarteries --- p.49 / Chapter 3.3.6 --- Effect of addition of nicorandil Krebs or ST solution under H-R on EDHF-mediated relaxation in coronary microarteries --- p.49 / Chapter 3.3.7 --- Data analysis --- p.50 / Chapter 3.4 --- Results --- p.51 / Chapter 3.4.1 --- Resting force --- p.51 / Chapter 3.4.2 --- U46619-induced contraction force --- p.51 / Chapter 3.4.3 --- Partial pressure of oxygen in hypoxia --- p.51 / Chapter 3.4.4 --- EDHF-mediated relaxation in coronary microarteries --- p.51 / Chapter 3.4.4.1 --- Effect of H-R --- p.51 / Chapter 3.4.4.2 --- Combined effects ofH-R and ST solution on EDHF-mediated relaxation --- p.52 / Chapter 3.4.4.3 --- Effects of addition of nicorandil to Krebs or ST solution under H-R on EDHF-mediated relaxation --- p.52 / Chapter 3.5 --- Discussion --- p.53 / Chapter 3.5.1 --- EDHF-mediated relaxation after exposure to H-R --- p.53 / Chapter 3.5.2 --- EDHF-mediated relaxation after H-R in ST solution at different temperature --- p.54 / Chapter 3.5.3 --- Effect of addition of nicorandil to Krebs or ST solution during H-R on EDHF-mediated relaxation --- p.55 / Chapter 3.5.4 --- Clinical implications --- p.56 / Chapter Chapter 4. --- Hypoxia-Reoxygenation in Cardiac Microveins: Combined Effect with Cardioplegia and Temperature on the Endothelial Function --- p.68 / Chapter 4.1 --- Abstract --- p.68 / Chapter 4.2 --- Introduction --- p.69 / Chapter 4.3 --- Experimental design and analysis --- p.73 / Chapter 4.3.1 --- Vessel Preparation --- p.73 / Chapter 4.3.2 --- Normalization --- p.73 / Chapter 4.3.3 --- Hypoxia --- p.73 / Chapter 4.3.4 --- Effect of H-R on EDHF-mediated relaxation in cardiac micro veins --- p.74 / Chapter 4.3.5 --- Combined effects of H-R and ST solution on EDHF-mediated relaxation in cardiac microveins --- p.74 / Chapter 4.3.6 --- Data analysis --- p.75 / Chapter 4.4 --- Results --- p.75 / Chapter 4.4.1 --- Resting force --- p.75 / Chapter 4.4.2 --- U46619-induced contraction force --- p.76 / Chapter 4.4.3 --- Partial pressure of oxygen in hypoxia --- p.76 / Chapter 4.4.4 --- EDHF-mediated relaxation after H-R in Krebs solution at 37°C --- p.76 / Chapter 4.4.5 --- EDHF-mediated relaxation after exposure to H-R in ST solution at different temperatures --- p.77 / Chapter 4.5 --- Discussion --- p.78 / Chapter 4.5.1 --- Effect of H-R on EDHF-mediated relaxation --- p.78 / Chapter 4.5.2 --- Combined effects of H-R with ST solution on EDHF-mediated relaxation --- p.80 / Chapter 4.5.3 --- Clinical implications / Chapter Chapter 5. --- General Discussion --- p.89 / Chapter 5.1 --- EDHF-mediated endothelial function in porcine coronary circulation --- p.89 / Chapter 5.1.1 --- EDHF in porcine coronary microarteries --- p.92 / Chapter 5.1.2 --- EDHF in porcine cardiac veins --- p.90 / Chapter 5.2 --- Alteration of EDHF-mediated function after exposure to H-R --- p.91 / Chapter 5.2.1 --- In coronary microarteries --- p.91 / Chapter 5.2.2 --- In cardiac veins --- p.92 / Chapter 5.3 --- Alteration of EDHF-mediated function after exposure to ST solution under H-R --- p.92 / Chapter 5.3.1 --- In coronary microarteries --- p.93 / Chapter 5.3.2 --- In cardiac veins --- p.93 / Chapter 5.4 --- EDHF-mediated function in nicorandil-supplemented ST solution under H-R in coronary microarteries --- p.93 / Chapter 5.5 --- Clinical implications / Chapter 5.5.1 --- H-R injury --- p.94 / Chapter 5.5.2 --- H-R injury and cardioplegic solution --- p.95 / Chapter 5.5.2 --- Nicorandil-supplementation in cardioplegic solution --- p.95 / Chapter 5.6 --- Limitation of the study --- p.96 / Chapter 5.7 --- Future investigations --- p.96 / Chapter 5.8 --- Conclusions --- p.97 / References --- p.99

Wong Chi Ming. / "August 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 182-215). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Background. Diabetes mellitus is a complex metabolic disorder characterized by clustering of multiple cardiovascular risk factors. Diabetic albuminuria is associated with increased prevalence of both micro-vascular and macro-vascular complications. This thesis examined vascular function (Flow-mediated dilatation, FMD) in type 2 diabetic patients with particular emphasis on its relationships with nephropathy. Independent predictors for FMD in Chinese population using data from both diabetic and non-diabetic subjects as well as the predictive value of FMD on clinical endpoints and death in type 2 diabetic patients with nephropathy were examined. / Conclusions. In Chinese subjects with or without type 2 diabetes, hyperglycaemia, hypertriglyceridemia, smoking and albuminuria were independent predictors for FMD. Type 2 diabetic subjects with overt nephropathy had impaired endothelium-dependent and endothelium-independent dilatation, suggesting vascular dysfunction beyond the endothelium. In agreement with studies from Caucasians, smoking was the most important determinant for vascular dysfunction in Chinese type 2 diabetic patients with overt nephropathy. Furthermore, FMD was predictive of new onset of cardiovascular events and related death in Chinese type 2 diabetic patients with overt nephropathy. / In diabetic patients with overt nephropathy, smoking (current and ex-smokers), waist hip ratio (WHR) and serum creatinine were independent predictors for impaired FMD. The latter was predictive of advancement of IMT and was an independent predictor for new onset of combined cardiovascular diseases and related death after a follow up period of 42 months (log rank test=6.04, p=0.014 using Cox regression analysis) after controlling for all confounding factors. In addition, fasting total cholesterol and plasma glucose were predictive for all-cause mortality while serum creatinine predicted new onset of renal endpoint. In a subgroup analysis in diabetic patients with overt nephropathy, smokers who developed CVD or ESRD had greater diminution of FMD than those who did not develop clinical endpoints. / Methods and results. FMD was assessed using high-resolution ultrasound scan. In the cross-sectional study, the sample population was divided into four groups according to the presence or absence of type 2 diabetes and level of albuminuria. They included the non-diabetic group (N=52), diabetic group with normoalbuminuria (N=18), diabetic group with microalbuminuria (N=18) and diabetic group with overt nephropathy defined as macroalbuminuria and renal insufficiency (N=22). Compared to non-diabetic subjects, type 2 diabetic subjects with nephropathy had impaired FMD (4.54% +/- 2.25 vs. 2.50% +/- 2.31, p<0.05) and impaired GTN-dependent dilatation (GTND) (14.30% +/- 3.77 vs. 12.70% +/- 4.70, p<0.05). They also had reduced endothelium-dependent dilatation to endothelium-independent dilatation ratio when compared to non-diabetic subjects (0.19 +/- 0.17 vs. 0.32 +/- 0.15, p<0.05). These findings suggest that the impaired vascular dilatation was due to dysfunction of both endothelium and vascular smooth muscle cells. In the entire cohort, fasting plasma glucose, fasting triglyceride, smoking and albuminuria were independent predictors for FMD. / Lai Wai Keung Christopher. / "February 2006." / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6298. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 202-252). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Interaction of fluid with elastic tube is complicated issue studied by many scientific departments around the world. Object of this thesis is to analyze simplified one-dimensional model. At the beginning, used balance equations and basics of hyper-elasticity are presented. Then we review three most common materials used for the description of blood vessels and other soft tissues. For these materials we introduce a method which we use to derive a relation between tube deformation and transmural pressure (i.e. difference between inner and outer pressure). In mathematical section we give brief review of theory of nonlinear hyperbolic equations and some relatively new results in the field of existence and uniqueness of a solution of one-dimensional hyperbolic system. The "building stone" of these results is a solution of the so-called Riemann problem. We use a method for finding exact solutions to the Riemann problem to analyze studied model of fluid-tube interaction and study dependence of the qualitative behavior of the solution on the material properties of the tube wall.

Ho, Kwok Wa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 60-65). / Abstracts in English and Chinese. / Chapter Chapter I / Chapter 1.1. --- Thromboxane A2 (TP) Receptors --- p.1 / Chapter 1.1.1. --- Gene structure of human TP receptors --- p.1 / Chapter 1.1.2. --- Isoforms of TP receptor --- p.1 / Chapter 1.1.3. --- Distribution and expression of TP receptors in human --- p.2 / Chapter 1.1.4. --- Signal transduction of TP receptors --- p.4 / Chapter 1.1.5. --- Major agonists of TP receptor in animals and humans --- p.7 / Chapter 1.1.5.1. --- Thromboxane A2 --- p.7 / Chapter 1.1.5.2. --- Prostaglandin H2 --- p.7 / Chapter 1.1.6. --- Functional studies: effect of TP receptor activation and blockade on vascular tone and atherosclerosis --- p.8 / Chapter 1.1.6.1. --- Effect of TP receptor activation --- p.8 / Chapter 1.1.6.1.1. --- On vaso-contraction --- p.8 / Chapter 1.1.6.1.2. --- On vaso-relaxation --- p.9 / Chapter 1.1.6.2. --- Effect of TP receptor blockade --- p.9 / Chapter 1.1.6.2.1. --- On endothelium dependent vaso-contraction --- p.9 / Chapter 1.1.6.2.2. --- On animal models related to atherosclerosis --- p.10 / Chapter 1.1.7. --- Objectives of current study --- p.10 / Chapter 1.2. --- Periadventitial Adipose (Fat) Tissue --- p.12 / Chapter 1.2.1. --- "General function, distribution and classification of fat" --- p.12 / Chapter 1.2.2. --- Representative endocrine/paracrine role of adipose tissues --- p.13 / Chapter 1.2.2.1. --- Leptin --- p.13 / Chapter 1.2.2.2. --- Angiotensinogen --- p.14 / Chapter 1.2.3. --- Functional studies on vessels with periadventital fat attached -The beginning of the story of adipcyte-derived relaxing factor (ADRF) --- p.15 / Chapter 1.2.3. --- Mechanisms behind the action of ADRF --- p.17 / Chapter 1.2.3.1. --- Nature of ADRF --- p.17 / Chapter 1.2.3.2. --- The mechanisms controlling the release of ADRF --- p.17 / Chapter 1.2.3.3. --- Proposed mechanisms explaining the anti-contractile effect mediated by ADRF --- p.17 / Chapter 1.2.4. --- Objectives of current study --- p.20 / Chapter Chapter II / Chapter 2.1. --- Tissue Preparation --- p.21 / Chapter 2.1.1. --- Preparation of blood vessels --- p.21 / Chapter 2.1.2. --- Procedures to remove the endothelium --- p.21 / Chapter 2.2. --- The Organ Bath Setups --- p.22 / Chapter 2.3. --- Calculation of Results --- p.24 / Chapter 2.3.1. --- Calculation of active tension --- p.24 / Chapter 2.3.2. --- Measurement of dry weight of arterial rings --- p.24 / Chapter 2.3.3. --- Measurement of the weight for periadventitial fat --- p.24 / Chapter 2.3.4. --- Statistic analysis --- p.24 / Chapter 2.4. --- Chemicals and Solutions --- p.25 / Chapter 2.4.1. --- Chemicals --- p.25 / Chapter 2.4.2. --- Solutions --- p.26 / Chapter Chapter III --- Stimulation of TP receptors by U46619 inhibits cGMP dependent vaso-relaxation --- p.27 / Chapter 3.1. --- Detail methods and materials --- p.27 / Chapter 3.1.1. --- "Safety announcement, tissue preparation and materials" --- p.27 / Chapter 3.1.1. --- Protocol --- p.27 / Chapter 3.1.1.1. --- PartI --- p.27 / Chapter 3.1.1.2. --- Part II --- p.28 / Chapter 3.1.1.3. --- Part III --- p.28 / Chapter 3.2. --- Results --- p.29 / Chapter 3.2.1. --- Effect of U46619 on vaso-relaxation --- p.29 / Chapter 3.2.2. --- Effect of Rho kinase and phosphodiesterase inhibitor on the inhibitory effect of U46619 --- p.29 / Chapter 3.2.3. --- The effect of low concentration of U46619 on vaso-relaxation --- p.29 / Chapter 3.3. --- Discussion --- p.37 / Chapter 3.3.1. --- Implication of the current study --- p.37 / Chapter 3.3.2. --- Formulated Theory --- p.41 / Chapter Chapter IV --- Effect of periadventitial fat on anti-relaxation effect induced by U46619 - A preliminary test --- p.43 / Chapter 4.1. --- Detail methods and materials --- p.43 / Chapter 4.1.1. --- "Safety announcement, tissue preparation and materials" --- p.43 / Chapter 4.1.2. --- Protocol --- p.43 / Chapter 4.1.2.1. --- Part I --- p.43 / Chapter 4.1.2.2. --- Part II --- p.44 / Chapter 4.1.2.3. --- Part III --- p.44 / Chapter 4.1.2.4. --- Part IV --- p.44 / Chapter 4.2. --- Results --- p.45 / Chapter 4.2.1. --- Effect of periadventitial fat on vaso-relaxation of rings contracted by phenylephrine --- p.45 / Chapter 4.2.2. --- Effect of periadventitial fat on vaso-relaxation of rings contracted by U46619 plus phenylephrine --- p.45 / Chapter 4.2.3. --- Effect of S18886 on vaso-relaxation in endothelium removed rings --- p.45 / Chapter 4.2.4. --- Effect of elevated extracellular potassium ions on vaso-relaxation --- p.46 / Chapter 4.3. --- Discussion --- p.56 / Chapter 4.3.1. --- Implication of current study --- p.56 / Chapter 4.3.2. --- Improvements and future perspectives of current study --- p.58 / Summary --- p.59 / References --- p.60

Vascular casts of three chondrichthian, one dipnoan, one chondrostean and 14 teleostean species were examined by light and scanning electron microscopy in order to give a qualitative and quantitative analysis of interarterial anastomoses (iaas) that indicate the presence (or absence) of a secondary vascular system (SVS). Anastomoses were found to originate from a variety of different primary blood vessels, many of which have not been previously identified as giving rise to secondary vessels. Segmental arteries derived from the dorsal aorta and supplying body musculature were major sites of origin of the SVS, although there was considerable variation in where, in the hierarchy of arterial branching, the anastomoses occurred. The degree of investment in a SVS was species specific, with more active species having a higher degree of secondary vascularisation. This difference was quantified using an absolute count of iaas between Anguilla reinhardtii and Trachinotus baillonii. A range of general features of the SVS is also described. No evidence of iaas was found on the coeliac, mesenteric or renal circulation in any species. Evidence of interarterial anastomoses were lacking in the dipnoan (Sarcopterygii) and chondrichthyan species examined, suggesting that a SVS is restricted to actinopterygian fishes. The presence and distribution of a secondary vascular system does not appear to be exclusively linked to phylogenetic position, but rather to the physiological adaptation of the species. Histological sections of primary segmental arteries and associated interarterial anastomoses and secondary vessels from the long-finned eel, Anguilla reinhardtii, were examined by light and transmission electron microscopy. Secondary vessels were found to originate from the primary vasculature as depressions through the tunica intima and media, from where they ran perpendicularly to the adventitial layer, before coiling extensively. From here the anastomoses travelled a relatively linear path in the outer margin of the adventitia to re-anastomose with a secondary vessel running in parallel with the primary counterpart. Secondary vessels had a structure quite similar to that of primary vessels; they were lined by endothelial cells on a continuous basement membrane, surrounded by single layer of smooth muscle cells surrounding the vessel. Smooth muscle cells were also found in the vicinity of interarterial anastomoses in the adventitia, but these were more longitudinally orientated. The presence of smooth muscle cells on all aspects of the secondary circulation suggests that this vascular system is regulated in a similar manner as the primary vascular system. Because interarterial anastomoses are structurally integrated with the primary vessel from which they originate, it was anticipated that flow through secondary vessels would to some extent be affected by an increase in primary vascular tone. Immunohistochemical studies showed that primary segmental arteries displayed moderate immunoreactivity to antibodies against 5-hydroxytryptamine and substance P, while interarterial anastomoses and secondary vessels showed dense immunoreactivity. Secondary vessels were followed to the surface of the animal through consecutive sections, where they eventually give rise to capillary beds overlying the scales. Secondary capillary beds were found to supply chloride cells in the skin, suggesting that this vascular system may be involved in cutaneous ionic exchange. Branchial vascular casts from two species of Tetraodontiformes showed that the vessels previously reported as nutrient vessels are with certainty part of the secondary vascular system. In the three-barred porcupine fish, Dicotylichthys punctulatus, interarterial anastomoses originated at high densities from efferent filamental and the efferent branchial arteries, from where they formed progressively larger secondary vessels. Small branches of this vascular system entered the filament body, where it gave rise to numerous side-vessels along the way. Large secondary vessels running in parallel with the efferent branchial arteries were found to constitute an additional arterio-arterial pathway, in that they exited the branchial basket in company with the afferent mandibular artery, the carotid artery and the efferent branchial arteries, from where they gave rise to vascular beds immediately after exit. The secondary vessels in this species were not found to supply the filament musculature; rather this vascular system was supplied by a single vessel derived from the efferent branchial artery, running in parallel with the afferent branchial artery. Secondary vessels were not found on any branchial component in the banded toadfish, Marylina pleurosticta, but in all other aspects the branchial vascular anatomy was similar to that of D. punctulatus. It is proposed that four independent vascular pathways may be present in the teleostean gill. The blood volume and flow rates of the primary (PVS) and secondary vascular system (SVS) were examined in the catadromous euryhaline teleost Lates calcarifer in order to determine whether any of these parameters were subject to change in individuals acclimated to seawater, compared to a group acclimated to freshwater. There was no significant difference in any measured parameter for the two groups. The volumes of the SVS were 0.67 „b 0.13 and 0.76 „b 0.13 mL 100g-1 body mass for FW and SW acclimated animals respectively. This constituted approximately one-third of the total blood volume in both groups. Turnover times for the SVS ranged from 21.0 to 25.2 minutes, demonstrating in accordance with previous publications, that this system is considerably more dynamic than previously assumed.

Vascular casts of three chondrichthian, one dipnoan, one chondrostean and 14 teleostean species were examined by light and scanning electron microscopy in order to give a qualitative and quantitative analysis of interarterial anastomoses (iaas) that indicate the presence (or absence) of a secondary vascular system (SVS). Anastomoses were found to originate from a variety of different primary blood vessels, many of which have not been previously identified as giving rise to secondary vessels. Segmental arteries derived from the dorsal aorta and supplying body musculature were major sites of origin of the SVS, although there was considerable variation in where, in the hierarchy of arterial branching, the anastomoses occurred. The degree of investment in a SVS was species specific, with more active species having a higher degree of secondary vascularisation. This difference was quantified using an absolute count of iaas between Anguilla reinhardtii and Trachinotus baillonii. A range of general features of the SVS is also described. No evidence of iaas was found on the coeliac, mesenteric or renal circulation in any species. Evidence of interarterial anastomoses were lacking in the dipnoan (Sarcopterygii) and chondrichthyan species examined, suggesting that a SVS is restricted to actinopterygian fishes. The presence and distribution of a secondary vascular system does not appear to be exclusively linked to phylogenetic position, but rather to the physiological adaptation of the species. Histological sections of primary segmental arteries and associated interarterial anastomoses and secondary vessels from the long-finned eel, Anguilla reinhardtii, were examined by light and transmission electron microscopy. Secondary vessels were found to originate from the primary vasculature as depressions through the tunica intima and media, from where they ran perpendicularly to the adventitial layer, before coiling extensively. From here the anastomoses travelled a relatively linear path in the outer margin of the adventitia to re-anastomose with a secondary vessel running in parallel with the primary counterpart. Secondary vessels had a structure quite similar to that of primary vessels; they were lined by endothelial cells on a continuous basement membrane, surrounded by single layer of smooth muscle cells surrounding the vessel. Smooth muscle cells were also found in the vicinity of interarterial anastomoses in the adventitia, but these were more longitudinally orientated. The presence of smooth muscle cells on all aspects of the secondary circulation suggests that this vascular system is regulated in a similar manner as the primary vascular system. Because interarterial anastomoses are structurally integrated with the primary vessel from which they originate, it was anticipated that flow through secondary vessels would to some extent be affected by an increase in primary vascular tone. Immunohistochemical studies showed that primary segmental arteries displayed moderate immunoreactivity to antibodies against 5-hydroxytryptamine and substance P, while interarterial anastomoses and secondary vessels showed dense immunoreactivity. Secondary vessels were followed to the surface of the animal through consecutive sections, where they eventually give rise to capillary beds overlying the scales. Secondary capillary beds were found to supply chloride cells in the skin, suggesting that this vascular system may be involved in cutaneous ionic exchange. Branchial vascular casts from two species of Tetraodontiformes showed that the vessels previously reported as nutrient vessels are with certainty part of the secondary vascular system. In the three-barred porcupine fish, Dicotylichthys punctulatus, interarterial anastomoses originated at high densities from efferent filamental and the efferent branchial arteries, from where they formed progressively larger secondary vessels. Small branches of this vascular system entered the filament body, where it gave rise to numerous side-vessels along the way. Large secondary vessels running in parallel with the efferent branchial arteries were found to constitute an additional arterio-arterial pathway, in that they exited the branchial basket in company with the afferent mandibular artery, the carotid artery and the efferent branchial arteries, from where they gave rise to vascular beds immediately after exit. The secondary vessels in this species were not found to supply the filament musculature; rather this vascular system was supplied by a single vessel derived from the efferent branchial artery, running in parallel with the afferent branchial artery. Secondary vessels were not found on any branchial component in the banded toadfish, Marylina pleurosticta, but in all other aspects the branchial vascular anatomy was similar to that of D. punctulatus. It is proposed that four independent vascular pathways may be present in the teleostean gill. The blood volume and flow rates of the primary (PVS) and secondary vascular system (SVS) were examined in the catadromous euryhaline teleost Lates calcarifer in order to determine whether any of these parameters were subject to change in individuals acclimated to seawater, compared to a group acclimated to freshwater. There was no significant difference in any measured parameter for the two groups. The volumes of the SVS were 0.67 „b 0.13 and 0.76 „b 0.13 mL 100g-1 body mass for FW and SW acclimated animals respectively. This constituted approximately one-third of the total blood volume in both groups. Turnover times for the SVS ranged from 21.0 to 25.2 minutes, demonstrating in accordance with previous publications, that this system is considerably more dynamic than previously assumed.

For small diameter (<6 mm) blood vessel replacements, lack of collaterals and vascular disease preclude homografts; while synthetic analogs, ePTFE, expanded polytetrafluoroethylene, and PET, polyethyleneterephathalate, are prone to acute thrombosis and restenosis. It is postulated that the hierarchical assembly of cell populated matrices fabricated from protein analogs provides a new design strategy for generating a structurally viable tissue engineered vascular graft. To this end, synthetic elastin and collagen fiber analogs offer a novel strategy for creating tissue engineered vascular grafts with mechanical and biological properties that match or exceed those of native vessels. This work details techniques developed for the fabrication of prosthetic vascular grafts from a series of extracellular matrix analogs composed of nanofibrous collagen matrices and elastin-mimetic proteins, with and without cells, and subsequent evaluation of their biocompatibility and mechanical properties. The work details the fabrication and mechanical analysis of vascular grafts made from aforementioned protein analogs. Subesequent studies detail seeding and proliferation of rodent mesenchymal stem cells on protein-based composites to recapitulate the media of native vasculature. Finally detailing in vivo biocompatibility and stability of tissue engineered vascular grafts.

University of Macau / Institute of Chinese Medical Sciences