There is a huge unmet clinical need for a new, safe and effective minimally invasive treatment for Acute Ascending Aortic Dissection (AAAD) (1). In 2012 AAAD has a mortality rate of 1-2% per hour within the first 24 hours, and even with contemporary surgical techniques, advanced intensive and post operative care, the mortality from AAAD following surgery in most series remains in the unacceptable range of 10-30% at 30 days (2;3). 28% of patients presenting with AAAD are denied life saving surgery often because of age or co-morbidity - medical therapy alone associated with an in hospital mortality rate in excess of 50% (2;4-6). Currently available endovascular stent grafts used in the descending thoracic and abdominal aorta are not adequately designed to be utilised within the ascending aorta. They have a large stowed diameter 22-25 French (F), with a rigid covering of either Dacron or ePTFE, and a stiff inflexible delivery system unlikely to traverse the aortic arch without complication. While the contemporary results of elective surgery for ascending thoracic aortic aneurysm (ATAA) are good, with an elective mortality of <5%, surgical results for AAAD have improved little over the last 20 years, with a 30 day mortality rate between 10-30% (3;7). With the emerging role of endovascular stent grafts in the treatment of thoracic aneurysm and dissection, with shorter hospital stays and improved outcomes I believe now is the time for the development of a percutaneous solution for AAAD. Potential ascending thoracic aortic graft (ATAG) designs must take into account the very close proximity of intimal tear to both the coronary arteries and aortic valve, allowing a 4 good proximal graft seal without compromising coronary flow or aortic valve competence. ATAG should have a low profile, with a thin non porous covering and a flexible delivery sheath with accurate and precise deployment characteristics. Following a literature review and novel anatomical data collection from computerised tomography (CT) and magnetic resonance imaging (MRI) scans of AAAD and ATAA patient cohorts, it seems that 3 embodiments of ATAG should be designed and developed, all sharing advanced core technologies including a laser-cut nitinol stent frame, thin polyurethane (PU) material covering and accurate and precise deployment mechanisms: 1) The “supra-coronary tubular ATAG”, for treating AAAD with an intimal tear in the ascending aorta, no coronary or aortic valve involvement and adequate landing zones above the coronary arteries and before the right brachiocephalic trunk (RBCT). It is likely that this graft will be capable of treating at least a third of all patients with AAAD (8). 2) The “inverted t-shirt ATAG” to proactively protect coronary artery flow and achieve proximal seal within the sinuses in patients with an intimal tear in close association or involving the coronary arteries. 3) The “valved ATAG” to treat patients who have significant aortic regurgitation (AR), to achieve a proximal seal at the annulus when anatomy suggests it would be difficult to achieve with embodiment 1) or 2), and in those patients who have a hugely dilated aortic root, so that the ATAG can seal proximally at a relatively normal annulus size, and seal distally at a normal ascending aorta diameter 5 proximal to the RBCT. This could be the treatment option for the 25-35% of AAAD patients who currently require aortic valve repair or replacement (9). The most complex of the 3 devices above is embodiment 2), the “inverted t-shirt ATAG”, as it must ensure proximal aortic seal within an often dilated sinus, without compromise to aortic valve and proactively protect both coronary arteries with 2 coronary sleeves. Basic proof of concept (PoC) of this embodiment has been demonstrated in vitro within a normal sized aortic glass model, with some important study limitations, nevertheless it does demonstrate that tracking an ATAG branched graft with 2 coronary sleeves is possible over 3 guidewires and deploying accurately within the aortic root under both direct vision and fluoroscopy. Following successful PoC deployment I then specified and had manufactured a 2nd Generation ATAG (2G ATAG), with a laser-cut nitinol frame, longitudinal tie bars, and a novel thin PU graft covering material. The 2G ATAG has been shown to have adequate radial strength when compared to competitor devices, and can be stowed to 28 F for deployment. During ATAG development 2 patents have been filed, and I wrote with Professor Rothman a successful NIHR I4I grant for £743,000 to take ATAG from the current 28 F 2G device, towards the goal of an 18 F device with bench testing, in vitro flow rig and deployment analysis, and in collaboration with the Royal Veterinary College (RVC) into an animal model over the next 3 years (beyond the scope of this thesis). I hope that within this next development cycle ATAG can be iterated into a device that might be ready to embark on a first in man (FIM) trial to offer the AAAD population an effective and less invasive treatment strategy.

This study was conducted to test the hypothesis that, during renal development, the Na-K-2Cl cotransporter type 2 (NKCC2) activates the tonicity-responsive enhancer binding protein (TonEBP) transcription factor by creating medullary hypertonicity. TonEBP, in turn, drives the expression of aldose reductase (AR) and urea transporter-A (UT-A). Kidneys from 13- to19-day-old fetuses (F13-F19), 1- to 21-day-old pups (P1-P21), and adult mice were examined by immunohistochemistry. NKCC2 was first detected on F14 in differentiating macula densa and thick ascending limb (TAL). TonEBP was first detected on F15 in the medullary collecting duct (MCD) and surrounding endothelial cells. AR was detected in the MCD cells of the renal medulla from F15. UT-A first appeared in the descending thin limb (DTL) on F16 and in the MCD on F18. After birth, NKCC2-positive TALs disappeared gradually from the tip of the renal papilla, becoming completely undetectable in the inner medulla on P21. TonEBP shifted from the cytoplasm to the nucleus in both vascular endothelial cells and MCD cells on P1, and its abundance increased gradually afterward. Immunoreactivity for AR and UT-A in the renal medulla increased markedly after birth. Treatment of neonatal animals with furosemide dramatically reduced expression of TonEBP, AR, and UT-A1. Furosemide also prevented the disappearance of NKCC2-expressing TALs in the papilla. The sequential expression of NKCC2, TonEBP, and its targets AR and UT-A and the reduced expression TonEBP and its targets in response to furosemide treatment support the hypothesis that local hypertonicity produced by the activity of NKCC2 activates TonEBP during development.

Materials which exhibit non-linear mechanical behaviors under large deformations are generally classified as “soft matter”. Elastomers represent an important class of soft materials which have wide commercial applications and isotropic non-linear behavior. In contrast, biological materials have anisotropic responses due to their heterogeneous and composite architectures. The underlying microstructure determines the arterial macroscopic behavior and is represented through constitutive models to describe the stress-strain relationships. Mechanical characterization and development of constitutive models that describe these non-linear and anisotropic properties are essential to our understanding of the structure-property relationships in these materials. In this study, we use two model systems to link the local microstructure to the overall macroscopic behaviors of soft matter. First, we delineate the roles of individual network topological factors in determining the overall macroscopic behavior of isotropic silicone elastomers using specimens fabricated with differential amounts of crosslinking. We performed mechanical experiments, within a theoretically motivated continuum mechanical framework, using a custom made planar biaxial testing instrument. These experiments demonstrate the contributions of physical entanglements and chemical crosslinks to the overall mechanical properties of silicone elastomers. Further, we show that the slip-link form of strain energy function is better suited to describe the material properties in the low to moderate regions of the stress-strain behavior. However, this model does not predict the stiffening response of elastomers at higher deformations, which is better captured using the Arruda-Boyce form of strain energy function. To explore the effects of individual topological factors on the overall network properties, we performed swelling experiments of silicone specimens in xylene and quantified variations in the polymer-solvent interaction parameter, χ, given by the Frenkel-Flory-Rehner (FFR) model. Further, we characterized the viscoelastic properties using dynamic mechanical analysis. Our results show that χ is not a constant, as assumed in the FFR model, but bears a linear relation to the equilibrium polymer volume fraction. To characterize the contribution of trapped entanglements to the overall mechanical behaviors, we use scaling laws in polymer physics and investigate the dependence of equilibrium volume fraction and experimentally obtained elastic moduli. Further, dynamic mechanical analysis demonstrated an increase in complex modulus with increase in the cross linking density. Finally, we examined variations in the uniaxial and the dynamical mechanical properties of silicone elastomers with storage time. Our results show that the time dependent increase in the modulus correlated with the formation of slip-links in the samples aged for a significantly long time in air. Together, these comprehensive studies show the importance of individual network features which affect the overall macroscopic properties of elastomers. Second, we use a multilayered and composite arterial model system to explore the passive material properties of arteries due to anisotropic layouts of extracellular matrix proteins, collagen and elastin. We characterized the mechanical properties of diseased human ascending thoracic aortic dissected (TAD) tissues, obtained from consenting patients undergoing emergency surgical repair to replace the diseased region, using multiple biaxial tests. We fit these results to micro structurally motivated Holzapfel-Gasser-Ogden model which is frequently used in the arterial mechanics literature. Our results show a higher stiffness for TAD tissues as compared to control aorta, without the presence of atherosclerotic plaques or other arterial disease. To study the directional variation in the mechanical properties of TAD tissues, we compared the stiffness in circumferential longitudinal directions at high and low stress region of equibiaxial experimental data. We observed no differences in the stiffness of TAD tissues in the circumferential and longitudinal directions. Further, we do not see any directional variations in the ultimate tensile stress, maximum extensibility, and modulus calculated in the low stretch region of uniaxial stress-strain response in TAD tissues. Histological analysis of TAD tissues showed a decrease in elastin content and an increase in collagen content as compared to control tissues. Higher TAD tissue stiffness also correlated with reduced elastin content in the arterial walls. To investigate the strain rate dependence of measured mechanical properties we use high testing rates of 1mm/sec to show that the TAD tissues have higher stiffness in the circumferential direction as compared to longitudinal direction. Finally, we used peel experiments to quantify the rupture potential of aortic dissected tissues. Our results show that TAD tissues have reduced delamination strength between layers as compared to control aortic tissues. To the best of our knowledge, no previous study has reported the mechanical property of human TAD tissues and these are the only biomechanical results on TAD tissues reported in specimens from South Asian patients. We hope that such studies will be useful for researchers who rely on microstructure based constitutive models to accurately describe the mechanical environment of cells which are important in the remodeling of tissues and in numerical models to assess mechanical criteria which may lead to the growth or dissection of arterial tissues.

Abstract Long-term monitoring of the wild salmon (Salmo salar L.) stock of the Simojoki river and the stocked hatchery-reared salmon parr and smolts has provided a considerable amount of information on the development of the stock and factors affecting it. Data on the relationships between wild and reared salmon were collected by tagging and trapping both smolts and adult salmon having either a wild or reared background. The tag recapture rate of wild smolts was about twice as high as that of smolts stocked as two-year-olds and slightly greater than for smolts stocked as parr. When survival was measured in relation to the smolt size, the difference between the wild and reared smolts was even greater, and it seemed to be emphasized in years with a low survival rate. The difference observed between the wild and reared salmon in the smolt phase generally disappeared in the adult phase. When adult salmon returned to the river to spawn the difference in the timing of the ascent depended more on the age or sex of the salmon, and less on their origin. Similarly, the survival of adult salmon in the river before or after spawning and later after returning to the sea depended on the sex and age of the fish. The origin of fish affected their behaviour, the reared salmon wandering more than wild adults before settling down into spawning areas. When the yield of wild and reared smolts as returning adults was compared, the wild smolts gave the best results, although the survival from smolt to adult was low in all smolt groups, probably due to the high fishing pressure in the sea. The smolts stocked as parr and those stocked as two-year-old fish were similar in this respect. The former group gave better results if the yield was measured as the number of returning multi-sea-winter adults, while the latter group gave better results if one-sea-winter grilse were also included in the yield. The low yield of adult salmon from stocking and the generally low survival of smolt groups irrespective of their origin emphasises the importance of fishing regulations as a tool in the maintenance or enhancement of naturally reproducing salmon stocks. However, despite the low profitability of stocking, it probably safeguarded the existence of the wild Simojoki salmon stock during its critical phase in the early 1990s. At that time the fishing regulations were not strict enough to prevent the alarming decrease in the salmon stock, and the adult spawners produced by stocking of young salmon may have had a relatively higher value than their number suggests.

No description available.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Primary pulmonary hypertension (PPH) has an extremely poor prognosis with a mean survival time of 2‐3 years from time of diagnosis. Hemodynamically, PPH is defined with a mPAP of ≥ 25 mm Hg. Currently, RHC is the gold standard for measuring the arterial pressures and diagnosing PPH; however, it is an incredibly invasive procedure. Our study will show whether CT angiography can be considered as a non‐invasive alternative for diagnosing PPH. Studies in the past have shown CT measurements of the MPAD and MPAD/AAD ratio having strong correlations with PPH. In addition to those measurements, we want to show if other CT parameters also have a correlation with PPH. Some of these novel measurements include the interventricular septal deviation and the Elizabeth Taylor sign. The interventricular septum is normally bowing to the right in a non‐pathological state. If it is straight or bowing to the left, this will indicate increased right ventricular pressures which would be indicative of PPH. Straight will indicate increased RV pressures, and bowing to the left will be considered markedly increased RV pressures. The Elizabeth Taylor sign is the ratio of the diameter of the segmental bronchi and its corresponding artery. We will hypothesize that the artery will be much larger than the bronchi in patients with PPH. Other measurements will include the left and right pulmonary arteries. This study is a retrospective review of subjects who underwent an otherwise unremarkable CT pulmonary artery angiogram. Subjects with pulmonary embolism or other acute pulmonary diseases are excluded. For each subject, the following CT findings are obtained: main pulmonary artery diameter (mPAD), ratio of mPAD to ascending aorta, right and left pulmonary artery diameters, ratio of segmental pulmonary artery to corresponding bronchus, and interventricular septal displacement. Straightening of the interventricular septum qualifies as increased right ventricular septal pressure and right‐to‐left bowing of the septum qualifies as a marked increase. Mean pulmonary artery pressure measured on any prior/subsequent RHC or echocardiogram within 3 months of the CT is recorded. Any past medical history of connective tissue disease is noted. Descriptive data are calculated and correlations are done to assess for presence and strength of associations among variables. Data from 484 subjects are collected. Incidence rate of pulmonary hypertension isv13% (n=63). 52% (n=33) of the subjects with pulmonary hypertension are female with an average age of 55 years. mPA diameter (p<0.001), mPA:AA ratio (p<0.001), right (p<0.001) and left pulmonary artery (p=0.004) diameters are predictors of pulmonary hypertension. sPA:B ratio (p=0.08) and interventricular septal displacement (p=0.96) are not predictive of pulmonary hypertension. This study supports an association of mPA diameter, mPA:AA ratio, right and left pulmonary artery diameters with pulmonary hypertension diagnosed by RHC or echocardiogram. Prospective research is warranted to confirm and establish threshold values for each variable. Currently, an invasive RHC remains the most accurate method of diagnosis. Correlating CT findings with pulmonary hypertension would allow clinicians to use CT as a noninvasive screening tool.

Two types of placentitis were studied: ascending and nocardioform placentitis. Although the first diagnosis of nocardioform placentitis was made three decades ago, little is known about the disease, due to the lack of an experimental model. In attempt to develop a research model, Crossiela equi was inoculated through intrauterine, intravenous, intrapharyngeal, and oral routes, but none of the routes resulted in nocardioform placentitis. This may indicate that unidentified factors may play a role in disease pathogenesis and that simple presence of bacteria is not sufficient to induce nocardioform placentitis. The second and major component of this dissertation involved the identification of diagnostic markers for placentitis. Because ascending bacterial placentitis is readily and predictably induced using existing experimental models, this model was used to identify diagnostic markers for placentitis in maternal plasma and fetal fluids. Three potential biomarkers were examined: acute phase inflammatory proteins, steroid hormones produced by the fetoplacental unit, and protein composition of the fetal fluids. Of the three acute phase proteins investigated, serum amyloid A and haptoglobin but not fibrinogen increased in association with experimentally induced ascending placentitis. Androgens and progestins appear to be poor markers for placentitis. Serum estradiol 17β concentrations were reduced in mares with experimentally induced placentitis and appear to be a good marker for placentitis in mares. Different methods were used to study the protein composition of the fetal fluids. Alpha-fetoprotein was characterized as a major protein present in the equine fetal fluids, and this protein was elevated in plasma of mares with placentitis. In another study, using a high-throughput proteomic technique several new proteins were characterized in the amniotic and allantoic fluids of mares carrying normal pregnancies, and several previously uncharacterized proteins were detected in the allantoic fluid of mares with placentitis. Three secreting proteins were elevated in allantoic fluid of mares with experimentally induced ascending placentitis.

A previous thoracic aortic aneurysm time course study from our laboratory determined that ascending aortic dilation was significantly increased by day 5, and reached a plateau by day 28 of angiotensin II (AngII) infusion. We also found that mice had hemorrhage localized to the ascending aortas by day 5 of AngII infusion. The purpose of these studies was to provide mechanistic insight into the development of AngII-induced ascending aortic hemorrhage. Male C57BL/6 mice fed normal diet were subcutaneously infused with either AngII (1000 ng/kg/min) or saline for 5 days. To examine cellular heterogeneity, hemorrhaged ascending aortas were collected and sectioned serially for histological staining and immunostaining. I was unable to identify an entry point for blood into the media of the aortic root and ascending aorta. However, I found incomplete intimo-medial dissection near the hemorrhaged regions that may potentially be contiguous with the blood. To investigate infiltration of immune cells during AngII infusion, immunohistochemistry of hemorrhaged ascending aortas was performed. The numbers of macrophages and neutrophils in AngII-infused aortas were increased in both medial and adventitial areas when compared with saline-infused aortas. Therefore, infiltration of immune cells at the point of dissection is associated with aortic hemorrhage during AngII infusion.

No description available.

The aim of this study is to analyse a genetic and proteomic aspects that could play an important role in development of chosen cardiovascular disease. Matrix metalloproteinases are enzymes that contribute strongly to the degradation of extracellular matrix components. In this study the serological levels of MMP-2 and MMP-9 were investigated using immunological testing in patients with aortic valve disease and in patients with myocardial infarction. Significantly higher levels of MMP-2 and MMP-9 were determined in both above mentioned groups of patients. Association of serum levels of MMP-2 and MMP-9 and development of concomitant aortic dilatation was not confirmed in patients with aortic valve disease. Changes in serum levels within 24 hours and after 6 months post myocardial infarction were characterized. About 10 % of patients operated for aortic valve disease suffer simultaneously from ascending aortic dilatation. The current study did not reveal any significant genetic variation in TGFBR2 gene and in chosen exons of FBN1 gene in these patients. Further genetic research is needed to identify the cause of the pathology in aortic wall. Gene expression of selected genes was measured by microarray screening in patients with myocardial infarction. These genes were related to MMPs and did not show...