L’autophagie est une voie catabolique durant laquelle des constituants cytoplasmiques sont engloutis dans des vésicules à double membrane nommées autophagosomes. Elle sert à éliminer les protéines mal repliées ou les agrégats protéiques, à détruire les organites défectueux comme les mitochondries, le réticulum endoplasmique et les peroxysomes mais aussi des pathogènes intracellulaires. Le matériel séquestré dans les autophagosomes est ensuite envoyé, pour dégradation, vers le lysosome. La dégradation du matériel séquestré génère des nucléotides, des acides aminés et des acides gras qui seront recyclés en vue de la synthèse de macromolécules et de la génération d’ATP.Dans cette étude nous explorons l’aspect cellulaire et fonctionnel de la voie de l’autophagie chez Caenorhabditis elegans. Nous montrons que le génome du nématode contient deux homologues du gène autophagique de levure Atg8. Ces homologues codent pour les protéines LGG-1 et LGG-2 qui sont des protéines des membranes des autophagosomes. Ces protéines agissent de façon synergique dans les processus physiologiques impliquant l’autophagie, en l’occurrence, la longévité et la formation des larves dauer.Nous montrons également que l’autophagie est impliquée dans le maintien de l’homéostasie cellulaire chez les mutants ESCRT. Les complexes ESCRT sont impliqués dans l’adressage des protéines ubiquitinées vers les corps multi vésiculaires pour les dégrader. Les mutants ESCRT se caractérisent par des altérations cellulaires et développementales. Nos résultats indiquent que l’inactivation des ESCRT cause une augmentation du flux autophagique. L’inactivation de l’autophagie dans ces mutants exacerbe les défauts cellulaires alors que son induction protège de la dégradation. / Macroautophgagy is a catabolic process involved in the clearance of cellular components in the lysosome when cells face starvation conditions. This eukaryotic process requires the formation of double membrane vesicles named autophagosomes. Autophagy is implicated in the elimination of misfolded proteins, protein aggregates and long-lived or damaged organelles such as mitochondria, endoplasmic reticulum and peroxysomes. It is alos required for the clearance of intracellular pathogens. The material enclosed inside autophagososmes in degraded in the lysosome: nucleotides, amino-acids and fatty-acids are generated and reused for neosynthesis of macromolecules and ATP.In the present study, we are exploring the cellular and functional aspects of the autophagic pathway in Caenorhabditis elegans. We show that the genome of the worm contain two homologues of the Yeast autophagic gene, Atg8. These homlogues encode for two proteins namely, LGG-1 and LGG-2, which localize to the autophagosomal membranes. We have shown that this two proteins act synergistically in dauer formation and longevity.We have also shown that autophagy play an important role in maintaining cell homeostasis in endosomal maturation mutans. These latter mutants show defects in the ESCRT coplexes (Endosomal Sorting Complex Required for Transport). ESCRT complexes are required the recycling of cell surface receptors and for the sorting of ubiquitinated prtoteins into the multivesicular bodies. Mutations in the ESCRTs cause cellular et developmental defects. In our study, we show that autophagy is induced in these mutants and play a beneficial role in correcting cellular defects.

Imaging instruments are required for accurate tumor resection during neurosurgery, especially in the case of glioblastoma multiforme (GBM) - the most common and aggressive malignant glioma. However, current intraoperative imaging techniques for detection of glioma either suffer low sensitivity and low specificity or require a significant capital cost. Advances in diffuse reflectance spectroscopy and fluorescence spectroscopy have offered high sensitivity and high specificity in differentiating tumors from normal tissues with much lower capital cost. Whereas diffuse reflectance spectroscopy alone and fluorescence spectroscopy alone has been used in limited studies to differentiate normal brain tissues from brain tumors with moderate sensitivity and specificity, low specificity and sensitivity were usually observed when studying high grade glioma (HGG) such as GBM. Furthermore, optical properties and diffuse reflectance signal of HGG and low grade glioma (LGG) have not been observed separately, and thus a relation between optical properties and glioma progression has not been established. Intraoperative differentiation of GBM and LGG can be helpful in making treatment plan at the first surgery. This thesis focuses on characterizing a previous integrated system of diffuse reflectance spectroscopy and fluorescence spectroscopy to extract optical properties and fluorescence properties of LGG and GBM. First, tissue-simulating phantom models were developed to calibrate the integrated system. The direct method and Mie theory were used to calculate optical scattering of the phantoms while Beer-Lambert’s law was used to calculate optical absorption. Second, an experimental method was introduced to recover intrinsic fluorescence because the measured fluorescence signal is likely distorted by the presence of scatterers and absorbers in tissue (i.e. hemoglobin). Third, an experimental method was developed to recover optical properties of both GBM and LGG. In addition, the sensitivity and specificity of the integrated system was optimized. / Thesis / Doctor of Philosophy (PhD)

(1) Background: Astrocytic gliomas present overlapping appearances in conventional MRI. Supplementary techniques are necessary to improve preoperative diagnostics. Quantitative DWI via the computation of apparent diffusion coefficient (ADC) histograms has proven valuable for tumor characterization and prognosis in this regard. Thus, this study aimed to investigate (I) the potential of ADC histogram analysis (HA) for distinguishing low-grade gliomas (LGG) and high-grade gliomas (HGG) and (II) whether those parameters are associated with Ki-67 immunolabelling, the isocitratedehydrogenase-1 (IDH1) mutation profile and the methylguanine-DNA-methyl-transferase (MGMT) promoter methylation profile; (2) Methods: The ADC-histograms of 82 gliomas were computed. Statistical analysis was performed to elucidate associations between histogram features and WHO grade, Ki-67 immunolabelling, IDH1 and MGMT profile; (3) Results: Minimum, lower percentiles (10th and 25th), median, modus and entropy of the ADC histogram were significantly lower in HGG. Significant differences between IDH1-mutated and IDH1-wildtype gliomas were revealed for maximum, lower percentiles, modus, standard deviation (SD), entropy and skewness. No differences were found concerning the MGMT status. Significant correlations with Ki-67 immunolabelling were demonstrated for minimum, maximum, lower percentiles, median, modus, SD and skewness; (4) Conclusions: ADC HA facilitates non-invasive prediction of the WHO grade, tumor-proliferation rate and clinically significant mutations in case of astrocytic gliomas.

Low-grade gliomas tend to gradually infiltrate brain areas essential for functions such as speech and language, and during surgery these areas risk being damaged. Thus, patients with low-grade gliomas should undergo awake surgery while performing tasks that evaluate the language functions associated with these areas. In order to be suitable for intraoperative use, the language tasks must have an appropriate and even level of difficulty. Furthermore, it is important that the test examines the abilities intended, and therefore a wide range of intraoperative language taks is required. At The Uppsala University Hospital there is a current demand for a reading test that evaluates reading comprehension and semantic processing. The aim of this essay was to produce a Swedish equivalent to the semantic sentence completion test with closed context from the Dutch test battery DuLIP, which examines these abilites. Twenty four out of the 25 tasks from DuLIP were translated and adapted to Swedish, followed by a pilot trial to assess the quality of the produced test. As a result of the test not meeting the criteria set by the authors a revision of the tasks was made, and 11 additional tasks were created. Ultimately, a second pilot trial was conducted resulting in an intraoperative language test consisting of 26 tasks, that examines reading and semantic sentence completion ability.  Lågmaligna gliom infiltrerar ofta successivt hjärnområden som ansvarar för bl.a. språkförmåga och motorik och vid kirurgi riskerar dessa områden att skadas. Patienter med lågmaligna gliom bör därför opereras i vaket tillstånd, samtidigt som de utför testuppgifter som bedömer de funktioner som förknippas med områdena. För att kunna användas intraoperativt bör testuppgifterna ha en lämplig och jämn svårighetsgrad. Det är också viktigt att testet som används bedömer den förmåga som avses, och därför behövs ett stort utbud av intraoperativa språktester. På Akademiska sjukhuset i Uppsala efterfrågas ett högläsningstest som bedömer läsförståelse och semantisk bearbetning, vilket i nuläget inte finns på svenska. Syftet med denna uppsats var att framställa en motsvarighet till det semantiska meningskompletteringstestet med sluten kontext i det holländska testbatteriet DuLIP, vilket bedömer dessa förmågor. Tjugofyra av de 25 uppgifterna från DuLIP översattes och anpassades till svenska och sedan genomfördes en pilottestning för att undersöka det framtagna testets kvalité. På grund av att testet inte uppnådde författarnas kriterier gjordes en omarbetning av uppgifterna, och dessutom skapades 11 nya uppgifter. Slutligen genomfördes ytterligare en pilottestning, vilket resulterade i ett intraoperativt språktest med 26 uppgifter, som bedömer förmåga av högläsning och semantisk meningskomplettering.

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