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- Ali, Zaheer, 1984-
(author)
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Investigating mechanisms of angiogenesis in health and disease using zebrafish models
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Angiogenesis, the growth of blood vessels from an existing vasculature, can occur by sprouting from preexisting vessels or by vessel splitting (intussusception). Pathological angiogenesis drives choroidal neovascularization (CNV) in age related macular degeneration (AMD) which is commonly restricted under the retinal pigment epithelium (RPE), called occult CNV, but may also involve vessels penetrating through the RPE into the sub-retinal space. Pathological vessels are poorly developed, insufficiently perfused and highly leaky, phenotypes that are considered to drive disease progression and lead to poor prognosis. Currently, a number of anti-angiogenic drugs exists, the majority of which target vascular endothelial factor (VEGF), but although they often are highly beneficial for treating eye diseases in the short-term, they are generally of limited efficacy in other diseases such as cancer, and also have poorer efficacy when used for treatment of eye diseases in the long-term. A better understanding of the mechanisms underlying pathological angiogenesis can generate new targets for treatment leading to development of better drugs for cancer and retinopathies, but perhaps also other angiogenesis-dependent diseases, in the future. In this thesis mechanisms involved in developmental angiogenesis or pathological angiogenesis in the choroid, cornea or melanoma was identified. These findings highlight the need to further elaborate our knowledge related to angiogenesis in different tissues/conditions for a more targeted, and potentially effective treatment of diseases in the future.In paper I, we for the first time identified the choriocapillaries (CCs) in adult zebrafish and found that occult CNV could be induced by exposing the fish to severe hypoxia. Interestingly, we found that occult CNV relied on intussusception, involving not only de novo generation of intussusceptive pillars but also a previously poorly understood mechanism called pillar splitting. This involved HIF-VEGF-VEGFR2 signaling and evidence that this also occurred in both rats and humans suffering from AMD suggested that the mechanism was conserved and clinically relevant.In contrast, we found in paper II that the development of CCs in the zebrafish relies on sprouting angiogenesis, involve continuous remodeling, and delayed maturation of the vasculature in 2D. The initial development was found to occur by a unique process of tissuewide synchronized vasculogenesis. As expected, VEGFA via VEGFR2 was also critical for the development of these vessels in the zebrafish embryo, but surprisingly this was independent on hypoxia-inducible factor (HIF)-1.Inflammatory nuclear factor-kB (NF-kB) signaling is involved in the progression of angiogenesis, but this signaling pathway has mainly been studied in the inflammatory cells and the role of NF-kB in the endothelial cells during angiogenesis is poorly understood. In paper III, we found that blocking NF-kB signaling using a specific IKK2 blocker IMD0354, specifically blocks pathological as well as developmental angiogenesis by targeting endothelial cell NF-kB signaling in the endothelial cells. Using a rat model for suture-induced corneal neovascularization, IMD0354 treatment lead to reduced production of inflammatory C-C motif chemokine ligand 2 (CCL2), C-X-C motif chemokine ligand 5 (CXCL5) and VEGF, and thereby reduced pathological corneal angiogenesis in this model.Using the zebrafish tumor xenograft model in paper IV, we found an association between Microphthalmia associated transcription factor (MITF) and pigment epithelium derived factor (PEDF), which was involved in pathological tumor angiogenesis and metastasis. Similarly, in paper V we used zebrafish transplantation models to study and investigate the use of biocompatible polymers for the delivery of pro-angiogenic FGF-2 as a potential treatment strategy for ischemic diseases such as myocardial infarction (MI). Conclusively, this thesis provides new insights into diverse fields of angiogenic assays using zebrafish, and reveals new mechanisms of angiogenesis in health and disease. This work will hopefully provide a foundation for further studies into occult CNV related to AMD, a process that has not been possible to study previously in pre-clinical models. In addition, zebrafish xenograft or other transplantation models used in this work will likely be important to study cancer biology and to develop more attractive pharmaceutical preparations based on biocompatible hydrogels formulated as microspheres in the future.
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| 2. |
- Hu, Wei, 1985-
(author)
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Theoretical Study on Chemical Structures and Stability of Molecules in Metallic Junctions
- 2016
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Doctoral thesis (other academic/artistic)abstract
- In this thesis, we focus on the structural identification of the interface using surface enhanced Raman spectroscopy (SERS) and inelastic electron tunnelling scattering (IETS). Two different molecular junctions, namely gold/ trans-1,2-bis (4-pyridyl) ethylene/gold junction and gold/4,4'-bipyridine/gold junctions in various conditions were studied and the corresponding configurations were determined. The enhancement in SERS was also studied by employing the time-dependent density functional theory. Furthermore, we studied some properties of the interface, such as the stability of the adsorbates and charge transfer properties of molecular junctions. The decrease in the stability of molecules was found when adsorbed on metallic surface and trapped in metallic junctions. Our studies explained several puzzles and by rational design, more stable molecular devices were obtained.
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| 3. |
- Jensen, Lasse Dahl Ejby
(author)
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Mechanisms of malignant and non-malignant angiogenesis using zebrafish models
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Pathological angiogenesis significantly contribute to the onset, development and progression of most common and severe human diseases including cancer, metastatic disease, cardiovascular disease, age-related macular degeneration, diabetic retinopathy and retinopathy of prematurity. Under these pathological conditions, tissue hypoxia often acts as a trigger to switch on angiogenesis. However, there has been lacking non-invasive and clinically relevant animal models that allow us to study mechanisms of human diseases. Zebrafish, as a complementary animal model to mice, is a highly genetically and pharmacologically tractable vertebrate which is easily visualized during development. Zebrafish offers a unique opportunity to study angiogenesis under hypoxia. This thesis describes development and characterization of four novel zebrafish models in relation to hypoxia-induced angiogenesis, vascular and tumor pathology. Using these models, we demonstrate that hypoxia plays a causal role in development of retinopathy and cancer cell metastasis and thus provide important insights needed for the development of therapeutic approaches aimed at interfering with these processes. In paper I, we showed that hypoxia could induce neovascular retinopathy in zebrafish and this model is highly relevant to clinical retinopathy caused by diabetes. This zebrafish retinopathy model also allows us study the therapeutic potential of various antiangiogenic agents. In paper II, we demonstrate a novel principle that regulates blood perfusion in lymphatics as an effective defense against tissue hypoxia in zebrafish and kryptopterus bicirrhis. The arterial-lymphatic shunt is controlled by nitric oxide and the implication of this work is that NO-induced lymphatic perfusion might facilitate tumor cell spread from the blood stream into the lymphatic system. In paper III, we take advantage of the transparent nature of zebrafish embryos and availability of the transgenic strain fli1:EGFP to develop a zebrafish metastasis model. Using this model, we are the first to study the role of hypoxia in relation to angiogenesis in facilitating tumor cell dissemination, invasion and metastasis. To the best of our knowledge, this is the first animal model that allows scientists to study the early events of metastasis at a single cell level. In paper IV, We show that PI3 kinase is a key signaling component that mediates angiogenesis in the developing embryonic retina and in the regenerating adult fins. In conclusion, development of these zebrafish disease models have paved new avenues for studying mechanisms of pathological angiogenesis in malignant and non malignant diseases and offers unique opportunities for assessment of therapeutic potentials of known and novel drugs against these most common and lethal diseases.
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| 4. |
- Mukwaya, Anthony
(author)
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Regulation of inflammation and angiogenesis in the cornea
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Inflammation and angiogenesis, the growth of new blood vessels from pre-existing ones, are involved in tumor growth, ocular diseases and wound healing. In ocular angiogenesis, new pathological vessels grow into a specific eye tissue, leak fluid, and disrupt vision. The development of safe and effective therapies for ocular angiogenesis is of great importance for preventing blindness, given that current treatments have limited efficacy or are associated with undesirable side effects. The search for alternative treatment targets requires a deeper understanding of inflammation and how it can lead to angiogenesis in the eye in pathologic situations. This thesis provides new insights into the regulation of inflammation and angiogenesis, particularly at the gene expression and phenotypic levels, in different situations characterized by angiogenesis of the cornea, often called corneal neovascularization. For instance, specific genes and pathways are either endogenously activated or suppressed during active inflammation, wound healing, and during resolution of inflammation and angiogenesis, serving as potential targets to modulate the inflammatory and angiogenic response. In addition, as part of the healing response to restore corneal transparency, inflammation and angiogenesis subside with time in the cornea. In this context, LXR/RXR signaling was found to be activated in a time-dependent manner, to potentially regulate resolution of inflammation and angiogenesis. During regression of new angiogenic capillaries, ghost vessels and empty basement membrane sleeves are formed, which can persist in the cornea for a long time. Here, ghost vessels were found to facilitate subsequent revascularization of the cornea, while empty basement membrane sleeves did not revascularize. The revascularization response observed here was characterised by vasodilation, increased inflammatory cell infiltration and by sprouting at the front of the reperfused vessels. Importantly, reactive oxygen species and nitrous oxide signaling among other pro-inflammatory pathways were activated, and at the same time anti-inflammatory LXR/RXR signaling was inhibited. The interplay between activation and inhibition of these pathways highlights potential mechanisms that regulate corneal revascularization. When treating corneal neovascularization clinically, corticosteroids are in widespread use due to their effectiveness. To minimize the many undesirable side effects associated with corticosteroid use, however, identifying new and more selective agents is of great importance. Here, it was observed that corticosteroids not only suppressed pro-inflammatory chemokines and cytokines, but also activated the classical complement pathway. Classical complement may represent a candidate for further selective therapeutic manipulation to investigate its effect on treatment of corneal neovascularization.In summary, this thesis identifies genes, pathways, and phenotypic responses involved in sprouting and remodeling of corneal capillaries, highlights novel pathways and factors that may regulate inflammation and angiogenesis in the cornea, and provides insights into regulation of capillary regression and reactivation. Further investigation of these regulatory mechanisms may offer alternative and effective treatment targets for the treatment of corneal inflammation and angiogenesis.
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| 5. |
- Oliva, Delmy, 1967-
(author)
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Prediction of side effects from anticancer treatment with the purpose of increasing quality of life
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Cancer and its treatments can cause a variety of symptoms. Some of these symptoms are related to the disease and others are seen as a consequence of the treatment. Since patients experience side effects to different degrees despite undergoing the same treatment, it is hypothesized that there is a genetic factor. The individual variation that exists between different patients regarding nausea triggered by chemotherapy, radiotherapy induced skin reactions as well as sleep disorders associated with cancer could partly be explained by genetic differences. We have in these studies confirmed these individual differences. Previous nursing research has mainly focused on the symptoms themselves. The focus in this thesis are the following three main symptoms; nausea and vomiting related to chemotherapy, acute skin inflammation following radiotherapy and sleep problems associated with cancer diagnosis and -treatment.The aim of this thesis was to find biological markers that can identify the risk of and/or protective factors for nausea and/or vomiting (CINV) as well as understand its heterogeneity (Study 1 and 2). It also aimed to understand the individual factors behind acute radiation skin reactions (ARSR) (Study 3) and sleeping disturbances in patients treated for cancer (Study 4), permitting a more individualized care and optimized health-related quality of life (HRQoL).In Study 1 and 2 the patients themselves had to document in a diary their experience of nausea and vomiting and well-being. Well-being was considered as synonymous with quality of life. We found a variability and heterogeneity of those symptoms (Study 1). Three genetic markers, FAS/CD95, RB1/LPAR6 and CCL2 that could explain the individual differences and assess the risk of chemotherapy-induced nausea were found in Study 2.Acute radiation skin reactions (ARSR) along with itching and burning sensation associated with radiotherapy (RT) was assessed by the patients themselves (Study 3) with help of the VAS- and RTOG scales, scoring for visible redness. We found two possible genetic markers, XRCC2 and IFNG. Also, individual differences in symptoms behavior were found.Sleep disturbances were common and were reported with obvious individual differences [1]. For data collection were used a sleep questionnaire, the Medical Outcomes Study Sleep Scale (MOS), open ended questions and EORTC QLQ- C30 questionnaire of quality of life. Sleep, which is important for all primary body functions, is often affected in connection with cancer diagnosis and -treatment.Through collaboration between nursing staff and specialists in basic science, we have found that biological markers can help in creating individualized care. Knowledge of individual variations in the severity of chemo- or radiotherapy-induced side effects is important in order to better personalize the treatment and care, improve the treatment results and alleviate or prevent the side effects of oncological treatments. By linking symptoms to biological markers, it will hopefully be able to increase the patients’ total health-related quality of life, this being the main goal of this thesis.
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