Migraine is a complex neurological disorder that affects approximately 38 million Americans. For over 25 years, the neuropeptide calcitonin gene-related peptide (CGRP) has been implicated in the pathogenesis of migraine. In fact, several pharmaceutical companies are tailoring treatments to antagonize CGRP actions. However, due to the complexity of migraine, exactly how and where CGRP acts to contribute to migraine have remained controversial: whereas several studies suggest that CGRP acts in the central nervous system (CNS) in this context, others have indicated a role in the periphery. Central nervous system sites of action include the trigeminal nucleus and several higher brain regions, and peripheral sites include the vasculature and dural mast cells in the meninges. Among the sites of CGRP action, the trigeminal nerve, which is the major somatosensory structure of the face, is of particular interest because it bridges the CNS and the periphery. Migraine is generally thought to involve abnormal signaling in the trigeminovascular system, and about 50% of trigeminal neurons have CGRP immunoreactivity. Although the notion that CGRP has a central site of action in relation to migraine had gained ground over the past decade, the recent discovery that monoclonal antibodies against CGRP can prevent migraine attacks has resurrected the possibility that a peripheral site of action is involved as well. Clarification of the sites of CGRP action in migraine will be crucial to developing an understanding of mechanisms that underlie migraine so that future treatments can be rationally designed. One diagnostic criterion for migraine is photophobia, a painful and often debilitating response to non-noxious levels of light. Our laboratory previously developed a preclinical model of migraine in which the light-aversive behavior of mice is used as a surrogate of photophobia. Specifically, mice were sensitized to CGRP by introducing a nestin/hRAMP1 transgene. In these mice versus control littermates, light aversion in response to central (intracerebroventricular, ICV) injection of CGRP was enhanced in dim light. In wild-type mice, CGRP (ICV) also elicited aversion to very bright light; this did not occur in vehicle-treated mice. Additionally, I have shown that CGRP injected peripherally (intraperitoneal, IP) can induce significant light aversion in wild-type mice. I have begun to identify the sites of action outside of the central nervous system, using four lines of transgenic mice with different patterns of overexpression of CGRP receptors: global hRAMP1 mice (expression in all tissues), nestin/hRAMP1 mice (expression only in nervous tissue), tagln/hRAMP1 (expression only in smooth muscle cells), and tek2/hRAMP1 (expression in endothelial cells). As predicted, in the global hRAMP mice light aversion, in response, to IP-injected CGRP was enhanced. However, in nestin/hRAMP1 mice, only ICV-injected, and not IP-injected, CGRP induced enhanced light aversion. This finding suggests that peripheral CGRP activates neural pathways involved in light aversion, but by an indirect mechanism. To determine where in the periphery CGRP is acting, a pharmacological and genetic approach was taken. Since CGRP is one of the most potent vasodilators in the body, it is well positioned to have vascular effects that induce light aversive behavior. This hypothesis was based on findings that 1) intravenous administration of CGRP in human subjects can cause migraine pain, and 2) perivascular CGRP can sensitize the trigeminal nerve, which could alter synaptic transmission to the central nervous system and 3) CGRP monoclonal antibodies are effective in clinical trial and likely do not cross the blood brain barrier. Thus, there is a mechanism by which CGRP in the periphery can sensitize the trigeminal nerve and alter sensory perception, leading to photophobia. The role of the vasculature in migraine, specifically vasodilation, has been controversial and now the consensus is that it is neither necessary nor sufficient. First, I wanted to test the role of vasodilation in this model. I pharmacologically inhibited CGRP-induced vasodilation using two vasoconstrictors, phenylephrine and endothelin-1. Blocking CGRP-induced vasodilation partially attenuates the light aversive response. Moreover, mice that overexpress the CGRP receptor in smooth muscle, but not endothelial, cells exhibit enhanced light aversion indicating a role for vascular actions of CGRP in this preclinical model of migraine. These results present clear evidence that CGRP has actions on the vasculature to induce light aversion. Additionally, the inability of blocking vasodilation to completely rescue the light aversion suggests that the vasculature may not be the only peripheral target of CGRP in migraine pathophysiology. This work improves the understanding of peripheral CGRP actions in migraine and raises awareness that contribution of the vasculature in migraine should not be ignored. The identification of sites of CGRP action in regions inside and outside of the CNS could lead to improved and more successful therapeutics for migraine.

The retinal vasculature analysis plays an important role in the diagnosis of ophthalmological diseases, as well as general human disorders that manifest on the retina. The fundus photograph is a 2-D color image modality of the retina and is widely used in modern ophthalmology clinics due to its relatively low cost and its non-invasive access to the retina. However, due to the complexity of the retinal vasculature presented on the image and the large variation of the image quality, no automated method is able to re-construct the retinal vasculature (i.e. construct arteriovenous trees) satisfactorily, thus preventing its analysis on large-scale clinical datasets. In this thesis, we present a systematic and complete study to automatically construct the retinal vasculature on fundus photographs and apply it to a clinical dataset. First of all, a preliminary study is conducted to detect and classify important landmarks in the retinal vasculature using a machine learning method. The evaluation of this method reveals the difficulty of identifying each landmark as an independent target. Then a novel and more global method is proposed to construct retinal arteriovenous trees (A/V trees). The strategy of the proposed method is to build an over-connected vessel network, and separate it into vascular trees, then classify them into A/V trees. Particularly, by taking advantages of specific properties of the retinal vasculature, global and local information are combined together to recognize landmarks of the vasculature. Instead of recognizing each landmark independently as other methods do, this method considers the relationship between landmarks in a more global manner, thus recognizing them simultaneously and globally. With a special graph design, each landmark is associated with multiple possible configurations and costs, and a near optimal solution is selected by minimizing the costs of landmarks and the global property of the whole vascular network. With each landmark recognized, the A/V trees are easily inferred with a pixel classification method. By doing so, local noise in the images and local errors during pre-processing are corrected to some degree, and small vessels that are difficult to classify locally can also be recognized. The proposed method is compared with another method and the evaluation demonstrates its superiority. To demonstrate its potential applicability, we apply the proposed method on a cohort study data of HIV-infected patients with treatment. New metrics to analyze retinal vessel width is developed based on the A/V trees built using the proposed method, and it is compared with a conventional metric. Statistical analysis reveals the advantages of the new metric and thus indicates the benefit of the proposed method and its potential application on large datasets.

While previous research into the pathogenesis of ischaemic and reperfusion injuries has focussed on the cardiac myocyte, there is increasing evidence for a crucial role for coronary vascular injury in the genesis of the post-ischaemic phenotype [1-3]. Post-ischaemic vascular injury may be manifest as a transient or sustained loss of competent vessels, impairment of vascular regulatory mechanisms, and ultimately as the 'no-reflow' phenomenon (inability to sufficiently reperfuse previously ischaemic tissue despite the removal of the initial obstruction or occlusion). It is now appreciated that the earliest distinguishing feature of various forms of vascular injury (including atherosclerosis and infarction) is 'endothelial dysfunction', which is the marked reduction in endothelial-dependent relaxation due to reduced release or action of endothelial nitric oxide (NO). Importantly, vascular injury may worsen myocardial damage in vivo [4,5], significantly limiting tissue salvage and recovery. The pathogenesis of post-ischaemic vascular injury and endothelial dysfunction is incompletely understood, but has generally been considered to reflect a cardiovascular inflammatory response, neutrophils playing a key role. However, while blood-borne cells and inflammatory elements are undoubtedly involved in the 'progression' of vascular injury [6,7], accumulating evidence indicates that they are not the primary 'instigators' [8]. It should be noted that a wealth of controversial findings exists in the vascular injury literature and mechanisms involved remain unclear. Indeed, multiple mechanisms are likely to contribute to post-ischaemic vascular injury. Adenosine receptors are unique in playing a role in physical regulation of coronary function, and also in attenuating injury during and following ischaemia. While the adenosine receptor system has been extensively investigated in terms of effects on myocardial injury [9,10], little is known regarding potential effects of this receptor system on post-ischaemic coronary vascular injury. This thesis initially attempts to further our understanding of the role of adenosine in normal coronary vascular function, subsequent chapters assess the effect of ischaemia-reperfusion on vascular function, and adenosine receptor modification of vascular dysfunction in the isolated asanguinous mouse heart. Specifically, in Chapter 3 the receptor subtype and mechanisms involved in adenosine-receptor mediated coronary vasodilation were assessed in Langendorff perfused mouse and rat hearts. The study revealed that A2A adenosine receptors (A2AARs) mediate coronary dilation in the mouse vs. A2B adenosine receptors (A2BARs) in rat. Furthermore, responses in mouse involve a sensitive endothelial-dependent (NO-dependent) response and NO-independent (KATP-mediated) dilation. Interestingly, the ATP-sensitive potassium channel component predominates over NO-dependent dilation at moderate to high agonist levels. However, the high-sensitivity NO-dependent response may play an important role under physiological conditions when adenosine concentrations and the level of A2AAR activation are low. In Chapter 4 the mechanisms regulating coronary tone under basal conditions and during reactive hyperaemic responses were assessed in Langendorff perfused mouse hearts. The data support a primary role for KATP channels and NO in mediating sustained elevations in flow, irrespective of occlusion duration (5-40 s). However, KATP channels are of primary importance in mediating initial flow adjustments after brief (5-10 s) occlusions, while KATP (and NO) independent processes are increasingly important with longer (20-40 s) occlusion. Evidence is also presented for compensatory changes in KATP and/or NO mediated dilation when one pathway is blocked, and for a modest role for A2AARs in reactive hyperaemia. In Chapter 5 the impact of ischaemia-reperfusion on coronary function was examined, and the role of A1 adenosine receptor (A1AR) activation by endogenous adenosine in modifying post-ischaemic vascular function was assessed in isolated buffer perfused mouse hearts. The results demonstrate that ischaemia does modify vascular control and signficantly impairs coronary endothelial dilation in a model devoid of blood cells. Additionally, the data indicate that post-ischaemic reflow is significantly determined by A2AAR activation by endogenous adenosine, and that A1AR activation by endogenous adenosine protects against this model of vascular injury. Following from Chapter 5, the potential of A1, A2A and A3AR activation by exogenous and endogenous agonists to modulate post-ischaemic vascular dysfunction was examined in Chapter 6. Furthermore, potential mechanisms involved injury and protection were assessed by comparing effects of adenosine receptors to other 'vasoprotective' interventions, including anti-oxidant treatment, Na+/H+ exchange (NHE) inhibition, endothelin (ET) antagonism, and 2,3-butanedione monoxime (BDM). The data acquired confirm that post-ischaemic endothelial dysfunction is reduced by intrinsic A1AR activation, and also that exogenous A3AR activation potently reduces vascular injury. Protection appears unrelated to inhibition of ET or oxidant stress. However, preliminary data suggest A3AR vasoprotection may share signalling with NHE inhibition. Finally, the data reveal that coronary reflow in isolated buffer perfused hearts is not a critical determinant of cardiac injury, suggesting independent injury processes in post-ischaemic myocardium vs. vasculature. Collectively, these studies show that adenosine has a significant role in regulating coronary vascular tone and reactive hyperaemic responses via NO and KATP dependent mechanisms. Ischaemia-reperfusion modifies vascular control and induces significant endothelial dysfunction in the absence of blood, implicating neutrophil independent injury processes. Endogenous adenosine affords intrinsic vasoprotection via A1AR activation, while adenosinergic therapy via exogenous A3AR activation represents a new strategy for directly protecting against post-ischaemic vascular injury.

In the early 1920s, Otto Warburg demonstrated that tumor cells have a capacity to convert glucose and other substrates into lactic acid instead of CO2 and water, even under aerobic conditions. Consequently, Warburg assumed that the intracellular pH (pHi) of tumor was acidic. However, later studies have shown that maintenance of pHi within a pH range of 7.0-7.2 is necessary for normal cellular proliferation and that the extracellular pH (pHe) is partially acidic in solid tumors. A low pHe may be an important factor inducing invasive behavior in tumor cells. Research into causes and consequences of this acid pH of tumors are highly dependent on accurate, precise and reproducible measurements. Techniques for measuring tissue pHi and pHe have undergone great changes since 1950s. From microelectrode and dye distribution studies, measurement of pH underwent a revolution with the advent of pH-sensitive dyes that could be loaded into the cytosol. Further significant advances have come from the measurement of cell and tissue pH in whole organisms by magnetic resonance spectroscopy (MRS), magnetic resonance imaging (MRI) and pH-sensitive Positron Emission Tomography (PET) radiotracers.

Anandamide (AEA), a well characterized endocannabinoid that has actions at multiple targets in the eye, may have potential as a novel therapeutic in the treatment of retinal disease. However, AEA is rapidly degraded by fatty acid amide hydrolase (FAAH). Therefore this study examined the drug URB597, that inhibits FAAH degradation of AEA, to assess AEA effects in experimental models of retinal damage. The objectives were to: 1) evaluate changes present in the aging retina, 2) determine whether the aging retina is more susceptible to tissue damage, and 3) investigate whether increasing AEA can provide retinal neurovascular protection in young and aged retina following damage. The results from this study showed that URB597 had protective effects on retinal ganglion cells and retinal capillaries and inhibited phagocytotic MG in models of retinal damage in young, but not the aged retina.

<p>The vascular contribution to tumor radiation response is controversial, but may have profound clinical implications. This is especially true of a new class of radiation therapies which employ spatial fractionation techniques--high radiation doses delivered in a spatially modulated pattern across the tumor. Window chamber tumor models may prove useful in investigating vascular parameters due to their facilitation of non-invasive, serial measurements of living tumors. However, presently there do not exist automated and accurate algorithms capable of quantitatively analyzing window chamber data.</p><p>Here we attempt to address these two problems through (1) the generation of novel optical data processing techniques for the quantification of vascular structural and functional parameters, and (2) the application of these methods to the study of vascular radiation effects in window chamber models.</p><p>Results presented here demonstrate the versatility and functionality of the data processing methods that we have developed. In the first part of Aim 1, we have developed a vessel segmentation algorithm specifically designed for processing tumor vessels, which present a challenge to existing algorithms due to their highly branching, tortuous structure. This provides us with useful information on vascular structural parameters. In the second part of Aim 1, we demonstrate a complementary vascular functional analysis algorithm, which generates quantitative maps of speed and direction. We prove the versatility of this method by applying it to a number of different studies, including hemodynamic analysis in the dorsal window chamber, the pulmonary window, and after neural electro-stimulation. Both the structural and functional techniques are shown capable of generating accurate and unbiased vascular structural and functional information. Furthermore, that automated nature of these algorithms allow for the rapid and efficient processing of large data sets. These techniques are validated against existing techniques.</p><p>The application of these methods to the study of vascular radiation effects produced invaluable quantitative data which suggest startling tumor adaptations to radiation injury. Window chamber grown tumors were treated with either widefield, microbeam, or mock irradiation. After microbeam treatment, we observed a profound angiogenic effect within the radiation field, and no signs of vascular disruption. Upregulation of HIF-1, primarily in the tumor rim, suggested that this response may have been due to bystander mechanisms initiated by oxidative stress. This HIF-1 response may have also initiated an epithelial-mesenchymal transition in the cells of the tumor rim, as post-treatment observation revealed evidence of tumor cell mobilization and migration away from the primary tumor to form secondary satellite clusters. These data indicate the possibility of significant detrimental effects after microbeam treatment facilitated through a HIF-1 response.</p> / Dissertation

Endophyte-infected tall fescue produces many ergot alkaloids, which have been shown to be vasoconstrictive in various vessel types of bovine. On the other hand, substantial evidence has been reported on the vasodilative effects of formononetin and biochanin A in different vessel types in humans and rats. So, a study was conducted using mesenteric vasculature collected from heifers shortly after slaughter. After 2-h incubation with formononetin (F), biochanin A (B), or an ergovaline-containing tall fescue seed extract (EXT) and their combinations, vessels were mounted in a multi-myograph to determine their ergotamine-induced contractility. Results indicated that F and B at 1 × 10-6 M and their combination did not impact the contractile response to ergotamine in mesenteric vasculature. The pre-myograph incubation of mesenteric vasculature with EXT altered the contractile response manner to ergotamine. However, at higher concentration, F and B may alleviate the reduction of vasoconstriction caused by prior exposure to EXT. To our knowledge, this study was the first to investigate the interaction of ergot alkaloids and isoflavones on in vitro bovine mesenteric vasculature. However, further investigations are necessary to understand the mechanism behind the interaction of ergot alkaloids and isoflavones on vasoactivity.

Glioblastoma, grade IV glioma, is the one of the deadliest cancers, with a median survival of only 12-15 months despite aggressive treatment including surgery, chemotherapy and radiation. One hallmark of glioblastoma is the morphological and functional abnormalization of tumor blood vessels. The molecular mechanisms involved in this process and their functional and pathological implications are not yet fully understood. Indentification of molecular mechanisms that underlie vascular abnormalization in GBM is necessary to develop efficient treatment regimens for normalizing vascular function. By analyzing the RNA-content of laser microdissected vessels from human biobank specimens using affymetrix microarray analysis, we found that the abnormal glioblastoma vessels have a distinct gene expression signature. We found 95 genes which were differentially expressed in grade IV glioma vessels as compared to vessels in low grade tumors and control brain. 78 of which were up-regulated while 17 were down-regulated. Many of these genes are regulated by VEGFA or TGFβ signaling. In addition, we show a significant increase in Smad signaling complexes in the vasculature of human glioblastoma in situ, suggesting that TGFβ signaling may play important role in vessel abnormalization. CD93 is a single-pass transmembrane glycoprotein, which we found to be up-regulated in high grade glioma. Vascular expression of CD93 correlates to tumor grade in human glioma. Moreover, high grade glioma patients with high CD93 expression in the vasculature are associate with poor prognosis. We found that knocking down CD93 in endothelial cells with siRNA clearly impaired endothelial cell adhesion, migration and tube formation due to defects in cytoskeletal rearrangement. In addition, tumor growth was severely delayed in the CD93-/- mice. Pleiotrophin, a multi-functional heparin-binding growth factor, promotes glioma growth in several ways. Here, we identify pleiotrophin as a driver of vascular abnormalization in glioma. We found that high pleiotrophin expression correlates with poor survival of patients with astrocytomas. Pleiotrophin overexpression in orthotopic GL261 gliomas increases microvessel density, enhances tumour growth and decreases survival. Vessels in pleiotrophin-expressing gliomas are poorly perfused and display a high degree of abnormality, coinciding with elevated levels of vascular endothelial growth factor (VEGF) deposited in direct proximity to the vasculature. In addition to its role in vessel abnormalization, pleiotrophin enhanced PDGF-B-induced gliomagenesis. Taken together, our results indicate that PTN has an important role in glioma initiation and establishment of the characteristic abnormal tumor vasculature in glioblastoma, identifying PTN as a potential target for therapy.

Induction of an endogenous antibody response by therapeutic vaccination could provide an alternative to cost-intensive monoclonal antibody-based treatments for cancer. Since the target of a cancer vaccine will most likely be a self-antigen, self-tolerance of the immune system must be circumvented. Using fusion proteins consisting of the self-antigen to be targeted and a part derived from a foreign antigen, it is possible to break tolerance against the self-antigen. Furthermore, a potent adjuvant is required to support an immune response against a self-molecule. Currently no adjuvant suitable for this purpose is approved for use in humans. This thesis describes the development of a therapeutic vaccine targeting the vasculature of tumors. As tumor cells have developed strategies to escape immune surveillance, targeting of molecules associated with the tumor stroma is an interesting alternative. The alternatively spliced extra domain-A and B (ED-A and ED-B) of fibronectin and the glycan-binding protein galectin-1 are selectively expressed during events of tumor angiogenesis. We have designed recombinant proteins to target ED-B, ED-A and galectin-1, containing bacterial thioredoxin (TRX) as a non-self part, resulting in TRX-EDB, TRX-EDA and TRX-Gal-1. Vaccination against ED-B induced anti-ED-B antibodies and inhibited growth of subcutaneous fibrosarcoma. Immunization against ED-A decreased tumor burden and reduced the number of lung metastases in the MMTV-PyMT model for metastatic mammary carcinoma in a therapeutic setting. Analysis of the tumor tissue from ED-B and ED-A-immunized mice indicated an attack of the tumor vasculature by the immune system. Finally, we show that galectin-1 immunization reduced tumor burden and increased leukocyte numbers in the tumor tissue. Galectin-1 is pro-angiogenic and immunosuppressive, and therefore allows simultaneous targeting of fundamental characteristics of tumorigenesis. We furthermore show that the biodegradable squalene-based Montanide ISA 720 combined with CpG oligo 1826 (M720/CpG) is at least as potent as Freund’s adjuvant with respect to breaking self-tolerance, when comparing several immunological parameters. Freund’s is a potent but toxic adjuvant used in the majority of preclinical studies. The work presented in this thesis shows that therapeutic cancer vaccines targeting the tumor vasculature are a feasible and promising approach for cancer therapy.

Intrapulmonary arteriovenous anastomoses (IPAVA) have been known to exist as part of the normal pulmonary vasculature for over 50 years but have been underappreciated by physiologists and clinicians. Using a technique called saline contrast echocardiography we and others have demonstrated that during exercise or when breathing low oxygen gas mixtures IPAVA open, but breathing 100% oxygen during exercise prevents them from opening. However, the mechanism(s) for this dynamic regulation and the role IPAVA play in affecting pulmonary gas exchange efficiency remain unknown. In Chapter IV the infusion of epinephrine and dopamine into resting subjects opened IPAVA. While it is possible this opening was due to the direct vasoactive action of these catecholamines, the opening may simply be due to increases in cardiac output and pulmonary artery systolic pressure secondary to the cardiac effects of these drugs. In Chapter V I used Technetium-99m labeled macroaggregated albumin (99mTc-MAA) to quantify blood flow through IPAVA in exercising healthy humans. Initial attempts to correct for attenuation of the emitted signal were unsuccessful due to the time necessary for data acquisition and the resulting accumulation of free-99mTc. However, I used a blood sample to calculate freely circulating 99mTc which could be subtracted from the shunt fraction. Using this procedure I demonstrated for the first time using filtered solid particles that breathing 100% oxygen reduces blood flow through IPAVA during exercise. Finally, in Chapter VI I tackled the elephant in the room surrounding IPAVA in healthy humans: do these vessels play a role in pulmonary gas exchange efficiency? Our data suggest that the efficiency of pulmonary gas exchange is dependent on the driving pressure gradient for oxygen and the distance to blood flowing through the core of IPAVA. As such, with increases in exercise intensity the diffusion distance and transit time of blood at the core of IPAVA prevent complete gas exchange, thus blood flow through IPAVA acts as a shunt. This dissertation includes previously unpublished co-authored material.