37 research outputs found

    Investigating immunological and metabolic pathways involved in the pathogenesis of chronic liver disease

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    Chronic liver disease affects a large number of people with a rising incidence, and is characterized by the development of liver fibrosis, eventually resulting in cirrhosis, Treatment options for end-stage liver disease are limited and liver cirrhosis represents the main risk factor for hepatocellular carcinoma (HCC), highlighting the need for novel therapeutic approaches. In this thesis, metabolic as well as immunological pathways contributing to the development of liver fibrosis and subsequent HCC have been investigated. Hepatic stellate cells (HSCs) are considered as the key players in fibrosis development, as their activation results in excessive extracellular matrix deposition, leading to the establishment of liver fibrosis. In addition, tumour-stromal interactions between HSCs and HCC play a role in HCC pathogenesis, and are therefore considered as a potential target for novel HCC therapy. In this thesis, the role of the AMPK pathway in tumour-stromal interactions between HSCs and HCC has been investigated, with a special focus on pharmacologically targeting AMPK in both HSCs and HCC. Moreover, the development of liver fibrosis and cirrhosis is accompanied by a chronic inflammatory immune response, fostering a pro-fibrogenic environment, especially in the context of autoimmune liver disease (AILD). Mucosal-associated invariant T cells (MAIT cells) are a recently discovered subset of innate like T cells that represent up to 40% of all liver lymphocytes. Besides being crucial for anti-microbial defence, MAIT cells contribute to autoimmune diseases and are thought to play an important role in tissue inflammation in the liver, as they secrete pro-inflammatory cytokines upon activation. Therefore, the role of MAIT cells for the development of liver fibrosis in AILD was explored. More specifically, the MAIT cell subset was characterized in human patients with AILD, and mechanisms of MAIT cell activation, as well as MAIT cell – HSC interactions were investigated

    Multivariate non-normally distributed random variables in climate research – introduction to the copula approach

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    International audienceProbability distributions of multivariate random variables are generally more complex compared to their univariate counterparts which is due to a possible nonlinear dependence between the random variables. One approach to this problem is the use of copulas, which have become popular over recent years, especially in fields like econometrics, finance, risk management, or insurance. Since this newly emerging field includes various practices, a controversial discussion, and vast field of literature, it is difficult to get an overview. The aim of this paper is therefore to provide an brief overview of copulas for application in meteorology and climate research. We examine the advantages and disadvantages compared to alternative approaches like e.g. mixture models, summarize the current problem of goodness-of-fit (GOF) tests for copulas, and discuss the connection with multivariate extremes. An application to station data shows the simplicity and the capabilities as well as the limitations of this approach. Observations of daily precipitation and temperature are fitted to a bivariate model and demonstrate, that copulas are valuable complement to the commonly used methods
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