Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Neste trabalho mostramos que o método de purificação empregando a coluna ANX Sepharose FF, alternando eluições com CaCl2 (pseudoafinidade) e NaCl, permite obter concentrados do complexo protrombínico e do fator VIII em uma etapa cromatográfica. Testamos as colunas ANX e Q Sepharose FF, monolito QA e membrana Sartobind Q e os tampões citrato, MES e Bis-Tris. Empregando a ANX Sepharose FF e o tampão citrato as proteínas do complexo protrombínico eluiram com CaCl2 25 mM e o FVIII com NaCl 500mM. A recuperação da atividade de FVIII foi de cerca de 60% e o fator de purificação de 220 vezes. Na fração contendo as proteínas do complexo protrombínico foram identificadas por espectrometria de massas a presença de fibrinogênio, proteína C4 do complemento e C4b Binding Protein. A análise das frações mostra que a presença destas proteínas não é devido à variação da concentração de CaCl2, possivelmente se deve à difusão lenta destas através da resina. Mais de 99% das proteínas do plasma não são adsorvidas na coluna e podem ser purificadas em etapas posteriores. / In this study we showed that the purification method employing the anion exchange column ANX Sepharose FF, and alternating CaCl2 (pseudoaffinity) and NaCl elutions, allows us to obtain concentrates of prothrombin complex proteins and factor VIII in a single chromatographic step. We tested the ANX, Q Sepharose FF and QA monolithic column and Sartobind Q membrane and the citrate, MES and Bis-Tris buffers. Using ANX Sepharose FF and the citrate buffer the prothrombin complex proteins eluted with 25 mM CaCl2 and FVIII with 500 mM NaCl. FVIII activity recovery was approximately 60% with a purification factor of 220. In the fraction containing the prothrombin complex proteins presence of fibrinogen, complement C4 and C4bBinding Protein were identified by mass spectrometry. Analysis of the fractions showed that their presence is not due to the variation of concentration of CaCl2, but possibly due to their slow diffusion through the resin. More than 99% of the plasma proteins are not adsorbed in the column and can be purified in following chromatographic steps.

Des cellules souches neurales (CSN) persistent dans le cerveau de mammifères adultes, y compris l'Homme. Les CSN participent à l'homéostasie tissulaire en générant de nouveaux neurones, permettant le remplacement de certains neurones morts. Cependant, la production de nouvelles cellules se fait en excès et plus de la moitié des cellules nouvellement générées meurent. Les cellules mortes ainsi que leurs débris doivent être éliminés par phagocytose. Dans une première partie de ma thèse, nous avons montré pour la première fois, que les CSN sont capables de phagocytose et que cette activité des CSN est régulée par la protéine S (ProS), une protéine vitamine-K dépendante, et son récepteur MerTK. Une rupture de l'homéostasie tissulaire conduit à des pathologies dont les cancers. Les interactions entre les CSN et des tumeurs cérébrales, les gliomes, sont duelles et étroites : des CSN dont la prolifération est dérégulée seraient à l'origine des tumeurs, mais, à l'inverse, les CSN saines peuvent migrer vers les gliomes et inhiber leur croissance. Dans une deuxième partie de ma thèse, nous avons confirmé l'effet anti-tumoral des CSN et nous avons établi que la ProS sécrétée par les gliomes attire les CSN vers la tumeur d'une part, et d'autre part, que les CSN diminuent la croissance tumorale par la sécrétion de leur ProS. Nous démontrons de plus, que ce processus s'accompagne d'une mort cellulaire des gliomes dont les débris sont phagocytés par les CSN. Mon travail de thèse a permis d'identifier de nouveaux mécanismes impliqués dans le maintien de l'homéostasie tissulaire par les CSN en conditions physiopathologiques. / Neural stem cells (NSC) persist in the brain of adult mammals, including humans. NSC contribute to tissue homeostasis maintenance through the genesis of new neurons that replace part of the cells that are maybe lost. However, the production of new cells is in excess and half of the newly generated cells die. Dead cells and their debris must be removed by phagocytosis. NSC express protein S (ProS) and its receptors, which are involved in phagocytosis. During the first part of my PhD thesis, we established for the first time, using in vitro and in vivo experiments, that NSC possess a phagocytic activity which is regulated by protein S (ProS), a vitamin K-dependent protein, and its receptor MerTK. Tissue homeostasis disruption leads to diseases such as cancers. Interactions between the NSC and brain tumors such as gliomas are dual and complex: glioma may arise from transformed NSC, but, conversely, normal NSC migrate towards glioma and inhibit their growth. Our study confirms the anti-tumoral effect of NSC and demonstrates, for the first time that ProS secreted by gliomas acts on Tyro-3 to attract NSC and that NSC secrete ProS which reduces tumor growth of ProS. In addition, we show that this process results in the death of glioma cells that are then phagocytosed by NSC. Our highlights identified novel mechanisms by which NSC contribute to tissue homeostasis in pathophysiological conditions.