Putative neuroprotective compounds in in vitro models of dopaminergic neurodegeneration

Parkinson´s disease (PD) is a debilitating age-related neurological disorder that affects various motor skills and can lead to a loss of cognitive functions. The motor symptoms are the result of the progressive degeneration of dopaminergic neurons within the substantia nigra. The factors that influence the pathogenesis and the progression of the neurodegeneration remain mostly unclear. This study investigated the role of various programmed cell death (PCD) pathways, oxidative stress, and glial cells both in dopaminergic neurodegeneration and in the protective action of various drugs. To this end, we exposed dopaminergic neuroblastoma cells (SH-SY5Y cells) to 6-OHDA, which produces oxidative stress and activates various PCD modalities that result in neuronal degeneration. Additionally, to explore the role of glia, we prepared rat midbrain primary mixed-cell cultures containing both neurons and glial cell types such as microglia and astroglia and then exposed the cultures to either MPP plus or lipopolysaccharide. Our results revealed that 6-OHDA activated several PCD pathways including apoptosis, autophagic stress, lysosomal membrane permeabilization, and perhaps paraptosis in SH-SY5Y cells. Furthermore, we found that minocycline protected SH-SY5Y cells from 6-OHDA by inhibiting both apoptotic and non-apoptotic PCD modalities. We also observed an inconsistent neuroprotective effect of various dietary anti-oxidant compounds against 6-OHDA toxicity in vitro in SH-SY5Y cells. Specifically, quercetin and curcumin exerted neuroprotection only within a narrow concentration range and a limited time frame, whereas resveratrol and epigallocatechin 3-gallate provided no protection whatsoever. Lastly, we found that molecules such as amantadine may delay or even halt the neurodegeneration in primary cell cultures by inhibiting the release of neurotoxic factors from overactivated microglia and by enhancing the pro-survival actions of astroglia. Together these data suggest that the strategy of dampening oxidative species with anti-oxidants is less effective than preventing the production of toxic factors such as oxidative and pro-inflammatory molecules by pathologically activated microglia. This would subsequently prevent the activation of various PCD modalities that cause neuronal degeneration.

Analysing local algorithms in location-aware quasi-unit-disk graphs

A local algorithm with local horizon r is a distributed algorithm that runs in r synchronous communication rounds; here r is a constant that does not depend on the size of the network. As a consequence, the output of a node in a local algorithm only depends on the input within r hops from the node. We give tight bounds on the local horizon for a class of local algorithms for combinatorial problems on unit-disk graphs (UDGs). Most of our bounds are due to a refined analysis of existing approaches, while others are obtained by suggesting new algorithms. The algorithms we consider are based on network decompositions guided by a rectangular tiling of the plane. The algorithms are applied to matching, independent set, graph colouring, vertex cover, and dominating set. We also study local algorithms on quasi-UDGs, which are a popular generalisation of UDGs, aimed at more realistic modelling of communication between the network nodes. Analysing the local algorithms on quasi-UDGs allows one to assume that the nodes know their coordinates only approximately, up to an additive error. Despite the localisation error, the quality of the solution to problems on quasi-UDGs remains the same as for the case of UDGs with perfect location awareness. We analyse the increase in the local horizon that comes along with moving from UDGs to quasi-UDGs.

Interruption and Uncooperativeness in Academic ELF Group Work : An Application of Linear Unit Grammar

This study addresses the challenge of analyzing interruption in spoken interaction. It begins with my observation of eight hours of academic group work among speakers of English as a lingua franca (ELF) in a university course. Unlike the common findings of ELF research which underscore the cooperative orientation of ELF users, this particular group gave strong impressions of interruption and uncooperativeness as they prepared a scientific group presentation. In the effort to investigate these impressions, I found that no satisfactory method exists for systematically identifying and analyzing interruptions. A useful tool was found in Linear Unit Grammar or LUG (Sinclair & Mauranen 2006), which analyzes spoken interaction prospectively as linear text. In the course of transcribing one of the early group work meetings, I developed a model of LUG-based criteria for identifying individual instances of interruption. With this system in place, I was then able to evaluate the aggregate occurrences of interruption in the group work and identify co-occurring interactive features which further influenced the perception of uncooperativeness. Finally, these aggregate statistics directed a return to the data and a contextually sensitive, qualitative analysis. This research cycle illuminates the interactive features which contributed to my own impressions of uncooperativeness, as well as the group members orientations to their own interruptive practice.

Role of CIP2A in carcinogenesis

Worldwide and notably in the developed countries, cancer is an increasing cause of morbidity and mortality, being the second most common cause of death after ischemic heart disease. Now and in the future new cancer cases need to be diagnosed earlier. Prognostic factors may be helpful in recognizing and handling those patients who need more aggressive therapy, and it is also desirable to predict treatment response accurately. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein predominantly expressed in malignant tissues and inhibiting protein phosphatase 2A (PP2A) activity; it is a promising target for cancer therapy. The aim of this thesis was to evaluate the prognostic role of CIP2A in solid cancers, and for this purpose to explore expression of CIP2A, and investigating regulation of CIP2A in order to gain insight into signalling pathways leading to alteration in prognosis. Patients diagnosed with gastric, serous ovarian, tongue, or colorectal cancer at Helsinki University Central Hospital were included. Tumour tissue microarrays assembled from specimens from these patients were prepared and stained immunohistochemically for CIP2A protein expression. Associations with clinicopathologic parameters and other biomarkers were explored, and survival analyses were done according to the Kaplan-Meier method. Study of the role of CIP2A in intracellular signalling in vitro involved gastric, ovarian, and tongue cancer cell lines. We found CIP2A to be highly expressed in gastric, ovarian, tongue, and colorectal cancer specimens. CIP2A was associated with clinicopathologic parameters characterizing an aggressive disease, namely advanced stage, high grade, p53 immunopositivity, and high proliferation index. CIP2A led to recognition of gastric, ovarian, and tongue cancer patients with poor prognosis, however, with a cancer type-specific cut-off level for prognostic significance. In tongue cancer, it served as an independent prognostic marker. In contrast, in colorectal cancer, CIP2A provided no prognostic value. In cancer cell lines, CIP2A was highly expressed at both protein and mRNA levels, and promoted cell proliferation and anchorage-independent growth. In gastric cancer, we demonstrated with a MYCER construct in mouse embryo fibroblasts that activation of MYC led to increased CIP2A mRNA expression, and hence we suggested that a positive feedback mechanism between CIP2A and MYC may potentiate and prolong the oncogenic activity of these proteins. We demonstrated in ovarian cancer an association between CIP2A and EGFR protein overexpression and EGFR gene amplification. In ovarian and tongue cancer cells we showed that depletion of EGFR downregulates CIP2A expression. In conclusion, high CIP2A expression occurred frequently among patients with aggressive disease. CIP2A may serve as a prognostic marker in gastric, ovarian, and tongue cancer and thus may help in tailoring therapy for cancer patients. The positive feedback mechanism between CIP2A and MYC, as well as the positive regulation of CIP2A by EGFR, are a few signalling pathways regulating and regulated by CIP2A. These and other mechanisms need to be studied further, however. CIP2A is a potential target for therapy, and its potential role as predictive marker and as a tumour marker in serum requires exploration.