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You, Yuying. "Cross-talk between marginal zone B cells and marginal zone macrophages." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2010. https://www.mhsl.uab.edu/dt/2010p/you.pdf.
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Watkins, Alan James. "Molecular characterization of splenic marginal zone lymphoma." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609484.
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Chen, Qifang. "Analysis of marginal ice zone noise events." Thesis, Massachusetts Institute of Technology, 1990. https://hdl.handle.net/1721.1/128940.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991.Includes bibliographical references (leaves 140-146).
by Chi-Fang Chen.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991.
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Di, Noto Giacomo. "Observations and modeling of the Marginal Ice Zone." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10228/.
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Global climate change in recent decades has strongly influenced the Arctic generating pronounced warming accompanied by significant reduction of sea ice in seasonally ice-covered seas and a dramatic increase of open water regions exposed to wind [Stephenson et al., 2011]. By strongly scattering the wave energy, thick multiyear ice prevents swell from penetrating deeply into the Arctic pack ice. However, with the recent changes affecting Arctic sea ice, waves gain more energy from the extended fetch and can therefore penetrate further into the pack ice. Arctic sea ice also appears weaker during melt season, extending the transition zone between thick multi-year ice and the open ocean. This region is called the Marginal Ice Zone (MIZ).
In the Arctic, the MIZ is mainly encountered in the marginal seas, such as the Nordic Seas, the Barents Sea, the Beaufort Sea and the Labrador Sea. Formed by numerous blocks of sea ice of various diameters (floes) the MIZ, under certain conditions, allows maritime transportation stimulating dreams of industrial and touristic exploitation of these regions and possibly allowing, in the next future, a maritime connection between the Atlantic and the Pacific. With the increasing human presence in the Arctic, waves pose security and safety issues. As marginal seas are targeted for oil and gas exploitation, understanding and predicting ocean waves and their effects on sea ice become crucial for structure design and for real time safety of operations. The juxtaposition of waves and sea ice represents a risk for personnel and equipment deployed on ice, and may complicate critical operations such as platform evacuations. The risk is difficult to evaluate because there are no long-term observations of waves in ice, swell events are difficult to predict from local conditions, ice breakup can occur on very short time-scales and wave-ice interactions are beyond the scope of current forecasting models [Liu and Mollo-Christensen, 1988,Marko, 2003].
In this thesis, a newly developed Waves in Ice Model (WIM) [Williams et al., 2013a,Williams et al., 2013b] and its related Ocean and Sea Ice model (OSIM) will be used to study the MIZ and the improvements of wave modeling in ice infested waters. The following work has been conducted in collaboration with the Nansen Environmental and Remote Sensing Center and within the SWARP project which aims to extend operational services supporting human activity in the Arctic by including forecast of waves in ice-covered seas, forecast of sea-ice in the presence of waves and remote sensing of both waves and sea ice conditions. The WIM will be included in the downstream forecasting services provided by Copernicus marine environment monitoring service.
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Rutherford, Steven John. "Arctic cyclones and marginal ice zone (MIZ) variability." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA268610.
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MARUYAMA, MITSUO, TADASHI MATSUSHITA, TOMOKI NAOE, HITOSHI KIYOI, SHINJI KUNISHIMA, TETSUHITO KOJIMA, MASAHITO IKAWA, et al. "RHOF PROMOTES MURINE MARGINAL ZONE B CELL DEVELOPMENT." Nagoya University School of Medicine, 2014. http://hdl.handle.net/2237/20548.
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Turchinovich, Gleb. "BKLF promotes B cell differentiation towards marginal zone lineage." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:25-opus-44233.
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Costa, Marcos Romualdo. "Novos progenitores na zona marginal do c?rtex cerebral em desenvolvimento." Brasil, 2006. https://repositorio.ufrn.br/jspui/handle/123456789/24238.
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Ao longo do desenvolvimento, as c?lulas neuroepiteliais do telenc?falo dividemse originando progenitores respons?veis pela gera??o sequencial dos diferentes tipos de neur?nios, astr?citos e oligodendr?citos do c?rtex cerebral. At? o presente, os progenitores telencef?licos estariam localizados nas zonas ventricular (ZV) e subventricular (ZSV). Sua posi??o ao longo dos eixos dorsoventral e rostro-caudal ? relacionada com territ?rios g?nicos e tipos celulares espec?ficos. Desta forma, observa-se a gera??o de neur?nios corticais glutamat?rgicos ou GABA?rgicos na ZV e ZSV do telenc?falo dorsal e ventral de roedores, respectivamente. Neste trabalho investigamos o potencial proliferativo in vivo e in vitro da zona marginal (ZM), conhecida por possuir neur?nios migrat?rios e diferenciados durante a corticog?nese. Determinamos o fen?tipo de c?lulas proliferativas da ZM e atrav?s de an?lise clonal utilizando infec??o por retrovirus contendo o gene para GFP (prote?na flourescente verde) acompanhamos as linhagens derivadas destes progenitores in vitro. C?lulas proliferativas in vivo foram marcadas atrav?s da administra??o do BrdU (bromodeoxiuridina, marcador da fase S do ciclo celular), combinada a ensaios imunohistoqu?micos para a identifica??o deste ant?geno e da forma fosforilada da histona 3 (expressa no final da fase G2 e durante a fase M do ciclo celular). Identificamos c?lulas proliferativas na ZM de camundongos a partir do dia embrinon?rio 14 (E14 - logo ap?s a divis?o da pr?-placa quando a ZM se torna distingu?vel) e por toda a corticog?nese com um aumento na proporc?o de c?lulas proliferativas de ~tr?s vezes em E18. As c?lulas proliferativas na ZM n?o expressam Pax6 ou Tbr2, fatores transcricionais caracter?sticos dos precursores da ZV e ZSV respectivamente. Ao longo da corticog?nese, esta popula??o precursora apresenta um padr?o de express?o do fator transcricional Olig2 seguindo um gradiente l?tero-medial, de modo que no per?odo perinatal todas as c?lulas proliferativas na zona marginal expressam o gene olig2. A an?lise das linhagens clonais geradas a partir destes precursores revelou um elevado potencial gliog?nico (~70% de clones gliais puros) quando comparado a ZV /ZSV (3,3%). Al?m disso, a ZM apresentou um significativo potencial neurog?nico, originando cerca de 30% de clones contendo neur?nios. Mostramos que os clones gliais puros da ZM s?o significativamente maiores que os da ZV. Conclu?mos, portanto, que a ZM dorsal ? um nicho neurog?nico e gliog?nico no c?rtex cerebral em desenvolvimento apresentando c?lulas proliferativas in vivo e in vitro com caracter?sticas fenot?picas distintas dos progenitores da ZV e ZSV. Atrav?s de estudos de linhagem clonal in vitro, demonstramos diferentes comportamentos proliferativos e potenciais neuro-gliog?nicos das c?lulas isoladas da ZM e da ZV/ZSV, indicando a exist?ncia de um novo tipo de progenitor no telenc?falo.
During development, telencephalic neuroepithelial cells proliferate and give rise to progenitors, which are responsible for the sequential generation of different types of neurons, astrocytes and oligodendrocytes in the cerebral cortex. To date, telencephalic progenitors would be located in the ventricular (VZ) and subventricular (SVZ) zones. Their position along the rostro-caudal and dorsoventral axis is related to gene expression territories and the generation of specific cell types, such that dorsal telencephalic VZ/ZVZ generates glutamatergic neurons and ventral VZ/ZVZ GABAergic neurons. In this work we investigated the in vivo and in vitro proliferative potential of the marginal zone (MZ) described to harbor migrating and differentiating neurons during corticogenesis. We determined the phenotype of MZ proliferative cells and by clonal analysis with infection by GFP (green fluorescent protein) containing retroviruses we followed the lineages derived from the progenitors in vitro. Proliferative cells in vivo were labeled by BrdU (bromodeoxyuridine, S phase cell cycle marker) combined to immunohistochemistry for the identification of BrdU antigen and the phosphorylated form of H3 ?histone (expressed at the end of G2 and during M phase of the cell cycle). We identified proliferative cells in mice MZ from embryonic day (E)14 (just after preplate division when MZ becomes distinguishable) and through all corticogenesis with a three fold increase in E18. Proliferative cells in the MZ do not express Pax6 or Tbr2, transcriptional factors typical of VZ and SVZ precursors respectively. During corticogenesis, this precursor population displays a latero-medial gradient of expression of Olig2, such that perinatally, all proliferative cells in the MZ express Olig2. Clonal lineage analysis from these precursors revealed a high gliogenic potential (~70% pure glial clones) when compared to VZ/SVZ (2,3%). Furthermore, MZ displays neurogenic potential since 30% of all clones contained neurons identified by class III ?-tubulin immunolabeling. Here we show that pure glial clones in the MZ are significantly larger than those generated by VZ. Concluding, the dorsal MZ is a neurogenic and gliogenic niche in the developing cerebral cortex containing proliferative cells with distinct phenotypic characteristics from the VZ and SVZ. By clonal lineage analysis in vitro, we demonstrated different proliferative behaviors and neuro-gliogenic potential from cells isolated from the MZ and VZ/SVZ indicating a novel type of progenitor in the cerebral cortex.
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Womack, Ashleigh Catherine Stevenson. "Atmospheric drivers of ice drift in the Antarctic marginal ice zone." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33982.
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Sea-ice drift in the Antarctic marginal ice zone (MIZ) was investigated using an array of five drifting ice buoys, deployed during the winter sea-ice expansion, in July 2017. An initial 15- day analysis of pancake ice drift is presented, using the cluster of buoys, which shows: (1) exceptionally fast ice drift speeds and increased meandering of the buoys during cyclone activity; (2) high correlation of drift velocities with the surface wind velocities, even at 100% remotely sensed ice concentration, indicating free drift conditions where ice drift is primarily governed by wind; and (3) the presence of a clear energy peak (»13.5 hour period), which is suggested to be excited by the passage of cyclones through the transfer of momentum from wind. Additionally, one of the buoys (buoy U1) drifted for approximately four months from the South Atlantic sector to the Indian Ocean sector of the Southern Ocean. The analysis of this buoy revealed that it remained within the MIZ even during the winter ice expansion, as the mixed pancake-frazil field was maintained. This allowed for a continued assumption of free drift conditions for buoy U1's full drift, where it continued to respond linearly to the momentum transfer from surface winds. The analysis of buoy U1 also indicated a strong inertial signature at a period of 13.47 hours however, the wavelet analysis indicated majority of the power remained within the lower frequencies. This strong influence at the lower (multiday) frequencies has therefore been identified as the primary effect of atmospheric forcing. When these lower frequencies were filtered out using the Butterworth high-pass filter it allowed the inertial oscillations to become more significant within the wavelet power spectrum, where it can be seen that these inertial oscillations were often triggered by the passage of cyclones. The initiation of inertial oscillations of sea ice has therefore been identified as the secondary effect of atmospheric forcing, which dominates ice drift at sub-daily timescales and results in the deviation of ice drift from a straight-line path. This comprehensive analysis suggests that the general concentration-based definition of the MIZ is not enough to describe the sea-ice cover, and that the MIZ, where ice is in free drift and under the influence of cyclone induced inertial motion, and presumably waves, can extend up to »200 km.
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Khalaf, Rossa, Fadi Tawadros, ASHA SEGIE, and Devapiran Jaishankar. "Marginal Zone Lymphoma with hyper viscosity syndrome responding to plasmapheresis and chemo immunotherapy." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/asrf/2018/schedule/173.
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Marginal zone lymphomas (MZLs) are a heterogeneous group of neoplasms that resemble the normal B-cell populations of the marginal zone of a lymph node. It includes three different subtypes, nodal, splenic, and extra -nodal, each, with overlapping features and yet unique characteristics. Nodal Marginal Zone lymphoma (NMZL) accounts for only 1% of all Non-Hodgkin Lymphoma (NHL). Marginal Zone lymphoma with plasmacytic differentiation is not very common. We report a unique case of Nodal marginal zone lymphoma initially presenting with lymphocytosis and lymphadenopathy, work up indicating low grade lymphoma, subsequently developing hyper viscosity syndrome due to symptomatic IgM monoclonal gammopathy. A 68 year old female was noted to have persistent leukocytosis with lymphocytic predominance after completing treatment for a urinary tract infection. Clinical exam revealed bilateral axillary adenopathy. CT scan of neck, chest, abdomen and pelvis revealed axillary, mediastinal and retroperitoneal adenopathy with splenomegaly. Chronic lymphocytic leukemia (CLL) was suspected and work up initiated. Peripheral blood Flow-cytometry revealed 24% small B-cells with surface kappa light chain restriction consistent with mature B-cell lymphoma or leukemia without typical immune phenotype of CLL. Lab reported significant elevation of total protein at 10 g/dl. Workup for para-proteinemia consistent with IgM level over 5000 mg/dl, with serum viscosity of 8. Axillary lymph node excisional biopsy reported marginal zone lymphoma with plasmacytic differentiation. Bone marrow biopsy demonstrated 42% monoclonal B-cells without co-expression of CD5 and CD23. FISH studies positive for duplication 1q and Molecular testing negative for MYDD88 mutation. Decision was made to initiate chemo therapy with R-CVP for a total of six cycles. Her treatment course was complicated by symptomatic hyper viscosity syndrome necessitating therapeutic plasmapheresis. Patient successfully completed chemo immunotherapy with normalization of blood counts, resolution of palpable adenopathy and splenomegaly. Nodal marginal lymphoma (NMZL) originates from nodal mono-cytoid or marginal zone B cells and the pathogenesis usually involves acquired mutations in oncogenes and tumor suppressor genes involving MLL2, PTTPRD, NOTCH2, and KLF2 genes. The median age is round 70 years with slight male predominance. The clinical picture varies and usually includes generalized lymphadenopathy along with B symptoms and infrequently with mild monoclonal gammopathy (any immunoglobulin subtype-IgM uncommon). Marginal Zone lymphoma with plasmacytic differentiation is not as common and shares immuno-histochemical features with lympho-plasmacytic lymphoma (LPL). They both express B cell markers CD19, CD20, and CD22) and not CD5, CD10 or CD23. Clinically, NMZL is more likely to present with prominent lymphadenopathy, while LPL can exclusively affect the marrow without extramedullary involvement. IgM levels in NMZL tend to be lower than in LPL, typically lower than 1000 mg/d. MYD88 mutation is very common in LPL, and can be seen in 10-15% NMZL. The presence of IgM monoclonal gammopathy increases the serum viscosity which can lead to serious neurologic and ophthalmologic complications. Treatment involves emergent plasmapheresis. Our case highlights a less common NHL, presenting with significant paraproteinemia and developing hyper viscosity syndrome with impressive response to plasmapheresis and chemo immunotherapy.
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Gruszka-Westwood, Alicja Maria. "The genetic characterisation of splenic lymphoma with villous lymphocytes." Thesis, Institute of Cancer Research (University Of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249713.
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Danou, Aliki. "The role of SIGNR1 and the marginal zone in experimental visceral leishmaniasis." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435498.
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Boutin, Guillaume. "Interactions vagues-banquise en zones polaires." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0050/document.
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La banquise, qui couvre de larges étendues de l’océan près des pôles, est une composante majeure du climat. Le réchauffement de la planète entraîne sa fonte massive, en particulier en Arctique.Là où l’extension de la banquise diminue, l’augmentation du fetch est associée à une élévation de la hauteur des vagues, laissant penser que les effets liés aux interactions vagues-glace pourraient s’accroître dans le futur. L’évolution rapide de la banquise associée à l’intensification des activités humaines dans les régions polaires pressent à améliorer notre connaissance de ces interactions.La banquise atténue les vagues. Elles peuvent néanmoins s’y propager et briser la glace sur de longues distances. L’atténuation dépend des propriétés de la glace comme l’épaisseur, la taille des plaques... Les plaques de glace une fois cassées sont plus susceptibles de dériver et de fondre. En outre, lors de l’atténuation, les plaques sont poussées dans la direction de propagation des vagues.Une représentation simple de la banquise dans un modèle de vagues intégrant une distribution de la taille des plaques nous a permis de montrer l’importance des mécanismes dissipatifs dans l’atténuation, notamment ceux induits par la flexion de la glace.Après avoir été validé, ce modèle a été couplé à un modèle de glace. La taille des plaques est échangée et utilisée dans le calcul de la fonte latérale. La force exercée par les vagues sur la banquise est également envoyée depuis le modèle de vagues. En été, cette force compacte la glace et tend à diminuer la fonte, augmentant significativement la température et la salinité des eaux de surface au bord de la banquiseSea ice, which covers most of the ocean near the poles, is a key component of the climate system. Global warming is driving its massive melting, especially in the Arctic. Where sea ice cover decreases, fetch increases leading to more energetic sea states. This means potentially enhanced wavesice interactions effects in the future. The quick evolution of sea ice extent and volume combined with the intensification of human activities in polar regions urge us to improve our understanding of waves-ice interactions.Sea ice attenuates waves. They can however propagate through it and break it far into the ice cover. Attenuation depends on ice properties such as floe size, thickness, etc. Once broken, resulting floes are more likely to drift and melt. In addition, wave attenuation yields a force which pushes the floes in the direction of wave propagation.A simplified representation of sea ice, including a floe size distribution, has been incorporated in a wave model.It allows us to show the important contribution of dissipative mechanisms in the wave attenuation, especially those induced by the bending of the ice plates. After validation, the modified wave model is coupled to an ice model. The floe size distribution is exchanged in the coupled framework and used in ice lateral melt computation. The force exerted by the waves on the ice floes is sent from the wave model and is shown to compact sea ice in summer. This reduces the melting and significantly increases the temperature and salinity in the surface ocean close to the ice edge
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Bascones, Gleave Sabrina 1985. "B cell ontogeny and stromal regulation of homeostatic antibody responses to commensal antigens in humans." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/664813.
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The spleen contains a unique subset of innate-like marginal zone (MZ) B cells that rapidly mount protective antibody responses to invasive encapsulated bacteria. Here we show that human splenic MZ B cells also mount homeostatic antibody responses to commensal antigens undergoing systemic translocation from mucosal surfaces. This humoral response decreased upon splenectomy and correlated with splenic capture of commensal antigens and with the generation of MZ B cell-derived plasmablasts and plasma cells following GC-independent and -dependent pathways. Remarkably, commensal antigens targeted marginal reticular cells (MRCs) in addition to macrophages. Besides canonical stromal properties, MRCs expressed macrophage-like immunoactivating functions that promoted robust MZ B cell responses to microbial ligands. These responses required both contact-dependent and contact-independent signals from MRCs, including MAdCAM-1 and VCAM-1 adhesion molecules as well as cytokines such as BAFF and APRIL, respectively. Thus, MRCs may function as stromal activator cells that integrate the innate and adaptive arms of the splenic immune system to orchestrate a secondary line of systemic defense against commensal antigens of mucosal origin.La melsa conté un particular tipus de cèl·lules B de la zona marginal (MZ) que ràpidament produeixen anticossos contra bacteris invasius encapsulats. Nosaltres demostrem que el limfòcits B de la MZ porten a terme respostes humorals, en condicions homeostàtiques, enfront antígens comensals que arriben a la circulació sanguínia provinents de la superfície de les mucoses. Aquesta resposta humoral disminueix en pacients sense melsa i es correlaciona amb la captura d’antígens per part d’aquest òrgan, provocant la diferenciació de les cèl·lules B de la MZ a cèl·lules plasmàtiques productores d’anticossos específics de bacteris comensals. Això es duu a terme mitjançant dues vies: l’independent i la dependent de limfòcits T. Sorprenentment, la captura d'antígens comensals a la melsa involucra cèl·lules reticulars marginals (MRC) i els macròfags. A més de les propietats típiques de cèl·lules estromals, les MRC presenten funcions immuno-activadores similars a les dels macròfags, promovent les respostes de les cèl·lules B de la MZ contra lligants microbians. Aquestes respostes requereixen senyals dependents de contacte amb les MRC, a través de molècules d'adhesió com MAdCAM-1 i VCAM-1, i senyals que no depenen del contacte intercel.lular, com la producció de les citocines BAFF i APRIL. Per tant, les MRC de melsa operen com a cèl·lules estromals activadores que integren les respostes immunològiques innates i adaptatives per orquestrar una segona línia de defensa contra antígens comensals provinents de les mucoses.
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Gentile, Maurizio 1981. "Role of mTOR in the activation of marginal zone B cells by TACI." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/318167.
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The marginal zone (MZ) of the spleen contains an innate-like subset of B cells that
mount rapid protective antibody responses to polysaccharides and lipids from bloodborne
viruses and bacteria. These antigens activate MZ B cells by engaging
somatically recombined B cell receptors (BCRs) and germline-encoded patternrecognition
receptors, including Toll-like receptors (TLRs). MZ B cells receive additional
co-stimulatory signals from a proliferation-inducing ligand (APRIL) and B cellstimulating
factor of the TNF family (BAFF), two tumor necrosis factor (TNF)-related
cytokines released mainly by macrophages, dendritic cells and neutrophils in response
to microbes. BAFF and APRIL stimulate MZ B cells through a poorly characterized
receptor called transmembrane activator and CAML interactor (TACI). Here we show
that TACI induces antibody production and class switching by activating the kinase
mammalian target of rapamycin (mTOR) through MyD88, an adaptor protein usually
associated with TLRs. The discovery of this rapamycin-sensitive signalling pathway
may facilitate the development of novel strategies for the modulation of protective or
pathogenic antibody responses emanating from MZ B cells.La zona marginal (ZM) de la melsa conté un subgrup de cèl∙lules B de tipus innat que organitzen de forma ràpida respostes d’anticossos protectors contra polisacàrids i lípids de virus i bacteris transmesos per la sang. Aquests antígens activen les cèl∙lules B de la ZM en interaccionar amb receptors de les cèl・lules B (BCR) que han patit recombinació somàtica i receptors de reconeixement de patrons, incloent els receptors de tipus Toll (TLR). Les cèl・lules B de la ZM reben senyals co-estimuladores addicionals del lligand inductor de proliferació (APRIL) i el factor estimulant de cèl・lules B de la família del TNF (BAFF), dos citocines relacionades amb el factor de necrosis tumoral (TNF) alliberades principalment per macròfags, cèl∙lules dendrítiques i neutròfils en desposta a microbis. BAFF i APRIL estimulen les cèl∙lules B de la ZM mitjançant un receptor poc caracteritzat anomenat activador de transmembrana i interactor de CAML (TACI). En aquest estudi demostrem que TACI indueix producció d’anticossos i canvi de classe de la cadena pesada de les immunoglobulines activant la quinasa diana de la rapamicina dels mamífers (mTOR) mitjançant MyD88, una proteïna adaptadora habitualment associada amb els TLRs. El descobriment d’aquesta via de senyalització sensible a la ramapicina podria facilitar el desenvolupament de noves estratègies per la modulació de les respostes protectores o patogèniques dels anticossos produïts per les cèl・lules B de la ZM.
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Rubtsov, Anatoly V. "Regulation of marginal zone B cell migration in the primary IgM antibody response /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2007.
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Thesis (Ph.D. in Immunology) -- University of Colorado Denver, 2007.Typescript. Includes bibliographical references (leaves 146-169). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;
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Rottier, Philip J. "Wave/ice interactions in the marginal ice zone and the generation of ocean noise." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385494.
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Murray-Brown, William. "The study of marginal zone B cell development in the spleens of CD1d-/- mice." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536029.
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Xue, Xiaoyan. "Identification of retinal stem cells in the ciliary marginal zone of the Xenopus retina." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/283870.
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Simango, Robert Zulu. "Gold exploration northeast of Ngundu Halt, northern marginal zone of the Limpopo Belt, Zimbabwe." Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1005844.
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Gold exploration was conducted in northern margin, granulite-facies rocks of the Limpopo Belt. Methods used in the prospecting include drainage, soil and rock geochemistry, geophysical surveys, geological mapping, trenching and diamond drilling. These techniques successfully led to the discovery of two medium size, mesothermal gold deposits (Grid 2s and Grid 4). Objectives of this study were to (a) document the exploration methodology used; (b) describe the regional geology; (c) establish a mineral deposit model; (d) outline the methods and results of various exploration techniques; (e) outline follow-up procedures and evaluation of anomalies; and (f) discuss results of the exploration exercise and conclusions. The granulite-facies terrain comprises Charno-enderbites, mafic and felsic to intermediate metavolcanic rocks and meta-sediments. Renco Mine situated immediately east of the study area, was selected as the ore deposit model for the exploration program. Gold mineralization occurs in shear and thrust zones within an enderbite. The gold deposits are structurally controlled by a first-order, Sinistral transcrustal Mauch Shear Zone, which is parallel to a regional east-northeast penetrative foliation. The deposits are in dilation zones where the Mauch Shear (a) is intersected by a dextral east-west shear (Grid 2s), or (b) has a sinistral splay (Grid 4 and Renco). Close to these deposits, the Mauch Shear is in contact with a "greenstone belt", which is a possible source of crustal metamorphic ore fluids and gold. The Grid 2s deposit contains fine-grained, disseminated free gold, and small amounts of pyrrhotite, pyrite and chalcopyrite in quartz veins within third-order shears in K-feldspar granite. K-feldspar, sericitic, silicic, sulphidation and carbonate alteration characterizes the deposit, which has a proposed mantle-degassing model. The Grid 4 deposit is magmatic porphyry-type, with CuMo and Au in third- and fourth-order shears respectively. Mineralization comprises disseminated to semi-massive pyrrhotite, pyrite, chalcopyrite, sphalerite, bismuth, molybdenite and gold. Wall rock alteration includes biotitic, chloritic, silicic, sulphidation and carbonate. In Grid 2s, Grid 4 and Renco deposits, the alteration mineral assemblages are in three facies, which are granulite, amphibolte and greenschist. In the three deposits, the mineralization occurs with the amphibolite-facies, indicating post-peak, retrograde metamorphic conditions.Illustrations (maps) only available in print form at Cory Library
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Dugge, Rucha [Verfasser]. "Tumor progression in gastric marginal zone B-cell lymphoma of MALT type / Rucha Dugge." Ulm : Universität Ulm, 2021. http://d-nb.info/1238690491/34.
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Davies, Rhiannon. "Modelling and observations of the atmospheric boundary layer of the Arctic marginal ice zone." Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/64046/.
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The Arctic is undergoing big changes, there has been a reduction in sea ice extent and an increase in the amount of thinner, newer ice. This changing surface causes challenges to numerical weather prediction and climate simulation, due to the very interconnected nature of the surface and atmosphere in the Arctic. Changes to the surface may impact on the air temperature, the surface fluxes of heat and moisture and the microphysics of clouds amongst others. These areas could also, in turn, change the surface. The Marginal Ice Zone (MIZ) is the area of the sea ice which is between the open water and solid ice, and is characterised by a complex and constantly changing ice surface. The impact of thinning ice in the MIZ was investigated using a series of idealised modelling experiments, and it was found that thinner sea ice in the MIZ would increase the surface temperature and fluxes of heat. In turn this causes the clouds, which formover the open water, to formcloser to the ice edge. The clouds were found to be thinner for the experiments with thinner ice, which resulted in them allowing more shortwave radiation to reach the surface. This result implies that thinning sea ice would act to further thin sea ice. Using observations from the Aerosol- Clouds Coupling And Climate Interactions in the Arctic (ACCACIA) campaign, two sets of model sensitivity studies were undertaken to test which boundary layer parametrisation schemes would performbetter. It was discovered that the boundary layer in the model is more sensitive to the surface representation rather than the choice of boundary layer scheme. These results point to the need for more work, both observations and modelling, on the sea ice and its impact on the atmosphere in order to better predict the changes the Arctic and the planet will undergo with a changing climate.
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Chéry, Nadège. "Inhibitory control of neurons in the marginal zone (lamina I) of the rat spinal cord." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0032/NQ64534.pdf.
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Gupta, Mukesh. "On the estimation of physical roughness of a marginal sea ice zone using remote sensing." John Wiley and Sons, Ltd, 2013. http://hdl.handle.net/1993/23836.
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This thesis provides insight into techniques for the detection and classification of various marginal ice zone roughnesses in the southern Beaufort Sea using in situ and satellite-based microwave remote sensing. A proposed model of surface roughness shows the dependence of circular coherence, a discriminator of roughness, on the roughness and dielectrics. A relationship between ice slopes in azimuth and range direction is derived. Microwave brightness temperature of open water is significantly correlated with wave height but not with the wind speed, having the strongest correlations for the H-polarization at both 37 and 89 GHz. A modified formula for the relationship between non-dimensional form of energy and wave age at wind speeds 0−10 m/s is obtained. The brightness temperature (April−June) of sea ice at H-polarization of 89 GHz is found to decrease with increasing roughness, and is attributed to the dominant contributions from rapidly varying thermodynamic properties of snow-covered sea ice.
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de, Jong Ehlke. "Assessment of the synoptic variability of the Antarctic marginal ice zone with in Situ observations." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31109.
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Knowledge of sea ice variability, which contributes to the detection of climate change trends, stems primarily from remote sensing information. However, sea ice in the Southern Ocean is characterised by large variability that remains unresolved and limits our confidence on the remotely sensed products. Although one of the biggest seasonal changes on Earth is the annual advance and retreat of the Antarctic sea ice cover, relatively little attention has been given to the processes by which the marginal ice zone (MIZ) edge forms and responds to synoptic events. This study aimed to assess the seasonal sea ice extent (SIE) of the MIZ by comparing sea ice observations estimated from aboard ship to high resolution passive microwave (PM) satellite imagery when transecting the MIZ. To achieve this, sea ice concentration (SIC) was derived from two AMSR (Advanced Microwave Scanning Radiometer ) products; the ARTIST (Arctic Radiation and Turbulence Interaction STudy) Sea Ice (ASI-AMSR ) and the bootstrap (BST-AMSR ). Theice concentration estimated from these PM satellite products was assessed against SIC observations collected from the S.A. Agulhas II (using the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol). This assessment took place over summer and winter for the years 2016 and 2017. After evaluating how well these PM-SIC estimates compared against the ASPeCt SIC observations, we found that there was good correlation over summer MIZ conditions, while over winter MIZ conditions the correlation was relatively poor. This highlighted winter limitations inherent in PM SIC estimates. Therefore, from these comparison results, an analysis of the seasonal SIE was accomplished while being aware of the winter limitations linked to the PM products. We inferred that the MIZ acts as an indicator for what the evolution of winter SIE might look like over the following months. In addition to winter limitations associated with PM-SIC retrievals, the ASPeCt SIC estimates, based on human interpretation of the sea ice conditions, was limited because of subjective bias. This resulted in the development of an algorithm to automatically acquire SIC from image stills and videos. This method can be used to obtain quantitative seaice data from vessels of opportunity without the need to have trained personnel on-board. In summary, this study assesses seasonal MIZ SIE within the Atlantic sector after highlighting the limitations associated with various SIC-retrieval methods.
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Lumpkin, Rutledge P. "A numerical study of a mesoscale eddy interaction with an ocean front in the marginal ice zone." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26114.
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Approved for public release; distribution is unlimitedThe East Greenland Current and its associated Marginal Ice Zone is a region of intense dynamical activity. A two layer, primitive equation, numerical model is used to simulate an eddy-jet interaction in the East Greenland marginal ice zone region. The effects of wind direction, topography, and sense of eddy rotation on the eddy-jet interaction are examined to determine the seaward ice transport, icebanding, and dipole formation. It is determined that an anticyclone (15 cm/s) interacting with a jet (30 cm/s) will develop a dipole that advects ice away from the ice edge. The dipole formation and ice advection away from the ice edge is not seen for a cyclone-jet interaction. It is also seen that a jet with no winds flowing parallel to the ice edge will create an iceband due to the cross ice edge Ekman transport. The interaction of both the cyclone and anticyclone with the jet creates downstream perturbations in the jet leading to a sinuous ice edge. Winds greater than 10 m/s dominate the ice dynamics over that induced by the ocean flow fields .
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Phan, Tri Giang. "The SWHEL model for studying B cell responses in tolerance and immunity." University of Sydney. Medicine, 2005. http://hdl.handle.net/2123/626.
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Classical immunoglobulin transgenic (Ig-Tg) mouse models such as the MD4 anti-hen egg lysozyme (-HEL) Ig-Tg line have been used extensively to study B cell responses in tolerance and immunity. This thesis describes a new generation of gene-targeted mice (designated SWHEL mice) whereby the VH10 Ig variable gene encoding the HyHEL-10 specificity of the original anti-HEL Ig-Tg mouse was targeted to the Ig heavy chain locus. B cells in the SWHEL mouse are therefore capable of undergoing class switch recombination (CSR) and somatic hypermutation (SHM), representing a major advance on the original MD4 mouse model. SWHEL mice were found to not only contain a large population of HEL-specific (HEL+) B cells but also a significant population of non-HEL-binding (HEL-) B cells generated by VH gene replacement. HEL+ SWHEL B cells were found to belong to the B2 lineage and displayed high levels of surface IgM. Nevertheless, they matured normally and colonised the primary B cell follicle and marginal zone (MZ) of the spleen. The SWHEL model thus provided an opportunity to re-examine some of the original observations made in the MD4 system and also to extend these observations, particularly with regard to the regulation of CSR by self-reactive B cells. As expected, analysis of SWHEL B cells exposed to high avidity membrane-bound HEL revealed that they underwent clonal deletion in the bone marrow (BM). More interestingly, analysis of HEL+ B cells exposed to low avidity soluble HEL revealed that they were able to emigrate from the BM to the spleen as anergic B cells. However, unlike anergic MD4 B cells, anergic SWHEL B cells were reduced in frequency, displayed an immature B cell phenotype, were excluded from the follicle and had a reduced lifespan. Direct measurement of B cell antigen receptor (BCR) occupancy by HEL and the frequency of HEL- competitor B cells was combined with mixed BM irradiation chimeras to demonstrate unequivocally that the difference in phenotype and fate of HEL+ B cells in the two systems was due solely to competition from HEL- B cells. In addition, the SWHEL model of B cell self-tolerance was used to show that while self-reactive B cells were hypo-responsive to BCR stimulation, BCR-independent signals delivered via anti-CD40 plus IL-4 or lipopolysaccharide could trigger them to undergo CSR and secretion of potentially pathogenic isotype-switched autoantibodies. Finally, the SWHEL model was used to study the responses of adoptively transferred follicular (Fo) and MZ B cells to in vivo activation with HEL conjugated to sheep red blood cells (HEL-SRBC). These studies revealed that both HEL+ MZ and Fo B cells were capable of mounting a robust T cell-dependent IgG1 antibody response to HEL-SRBC. However, HEL+ MZ B cells did not efficiently localise to the T cell-B cell border following antigen engagement and preferentially migrated to the bridging channels and red pulp. In contrast, HEL+ Fo B cells rapidly localised to the T cell-B cell border and subsequently colonised numerous germinal centres. As a result, the rate and pattern of SHM by HEL+ Fo and MZ B cells was shown to be distinct, with preferential targeting of mutations to the second complementarity-determining region in the former and to the second framework region in the latter. Together these data indicate illustrate the value of the SWHEL model and its potential to greatly advance the current understanding of B cell responses in tolerance and immunity.
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Phan, Tri Giang. "The SWHEL model for studying B cell responses in tolerance and immunity." Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/626.
Full textAbstract:
Classical immunoglobulin transgenic (Ig-Tg) mouse models such as the MD4 anti-hen egg lysozyme (-HEL) Ig-Tg line have been used extensively to study B cell responses in tolerance and immunity. This thesis describes a new generation of gene-targeted mice (designated SWHEL mice) whereby the VH10 Ig variable gene encoding the HyHEL-10 specificity of the original anti-HEL Ig-Tg mouse was targeted to the Ig heavy chain locus. B cells in the SWHEL mouse are therefore capable of undergoing class switch recombination (CSR) and somatic hypermutation (SHM), representing a major advance on the original MD4 mouse model. SWHEL mice were found to not only contain a large population of HEL-specific (HEL+) B cells but also a significant population of non-HEL-binding (HEL-) B cells generated by VH gene replacement. HEL+ SWHEL B cells were found to belong to the B2 lineage and displayed high levels of surface IgM. Nevertheless, they matured normally and colonised the primary B cell follicle and marginal zone (MZ) of the spleen. The SWHEL model thus provided an opportunity to re-examine some of the original observations made in the MD4 system and also to extend these observations, particularly with regard to the regulation of CSR by self-reactive B cells. As expected, analysis of SWHEL B cells exposed to high avidity membrane-bound HEL revealed that they underwent clonal deletion in the bone marrow (BM). More interestingly, analysis of HEL+ B cells exposed to low avidity soluble HEL revealed that they were able to emigrate from the BM to the spleen as anergic B cells. However, unlike anergic MD4 B cells, anergic SWHEL B cells were reduced in frequency, displayed an immature B cell phenotype, were excluded from the follicle and had a reduced lifespan. Direct measurement of B cell antigen receptor (BCR) occupancy by HEL and the frequency of HEL- competitor B cells was combined with mixed BM irradiation chimeras to demonstrate unequivocally that the difference in phenotype and fate of HEL+ B cells in the two systems was due solely to competition from HEL- B cells. In addition, the SWHEL model of B cell self-tolerance was used to show that while self-reactive B cells were hypo-responsive to BCR stimulation, BCR-independent signals delivered via anti-CD40 plus IL-4 or lipopolysaccharide could trigger them to undergo CSR and secretion of potentially pathogenic isotype-switched autoantibodies. Finally, the SWHEL model was used to study the responses of adoptively transferred follicular (Fo) and MZ B cells to in vivo activation with HEL conjugated to sheep red blood cells (HEL-SRBC). These studies revealed that both HEL+ MZ and Fo B cells were capable of mounting a robust T cell-dependent IgG1 antibody response to HEL-SRBC. However, HEL+ MZ B cells did not efficiently localise to the T cell-B cell border following antigen engagement and preferentially migrated to the bridging channels and red pulp. In contrast, HEL+ Fo B cells rapidly localised to the T cell-B cell border and subsequently colonised numerous germinal centres. As a result, the rate and pattern of SHM by HEL+ Fo and MZ B cells was shown to be distinct, with preferential targeting of mutations to the second complementarity-determining region in the former and to the second framework region in the latter. Together these data indicate illustrate the value of the SWHEL model and its potential to greatly advance the current understanding of B cell responses in tolerance and immunity.
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Jallades, Laurent. "Caractérisation moléculaire des délétions du chromosome 7q dans les lymphomes B de la zone marginale splénique." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10342.
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La délétion du chromosome 7q est l'anomalie cytogénétique la plus caractéristique du lymphome de la zone marginale splénique (LZMS). Une étude par hybridation génomique comparative de haute résolution a été conduite sur une série de 27 échantillons de LZMS afin de détecter des micro-remaniements du chromosome 7q. Une région commune de délétion (RCD) de 10,6 Mb a été délimitée sur le chromosome 7q. De plus, une microdélétion somatique du gène AHCYL2 (S-adenosyl-homocystéine hydrolase-like 2) a été détectée au sein de la RCD, définissant la plus petite RCD connue sur le chromosome 7q32 dans le SMZL et l'anomalie la plus fréquente de notre série (10/27, 37%). Bien que le séquençage du gène AHCYL2 n'a pas mis en évidence de mutation somatique, la délétion monoallélique du gène AHCYL2 est corrélée à la sous-expression de transcrits du gène AHCYL2 indiquant une haplo-insuffisance. La fonction précise de AHCYL2 reste inconnue, mais certaines données suggèrent que les protéines de type AHCYL peuvent réguler l'activité de l'enzyme AHCY (Sadénosyl- homocystéine hydrolase) et par conséquent affecter les mécanismes de transméthylation. En outre, nous avons identifié, pour la première fois dans le LZMS, une mutation R882H du gène DNMT3A (1/27, 3,7%) impliqué également dans les processus de méthylation. Ces résultats suggèrent que la dérégulation des voies métaboliques impliquées dans la méthylation peut jouer un rôle crucial dans la pathogenèse du LZMSThe chromosome 7q deletion is the most characteristic alteration in splenic marginal zone lymphoma (SMZL). High-resolution genome-focused approach was performed on 27 SMZL samples to identify submicroscopic genetic alterations on chromosome 7q. A 10.6 Mb-length common deleted region (CDR) of chromosome 7q was precisely delineated and a somatic microdeletion of the S-adenosyl-homocysteine hydrolase-like 2 (AHCYL2) gene was further detected within the CDR, defining the most frequent finding in this series (10/27, 37%) and the smallest CDR on chromosome 7q32. Although the sequencing of AHCYL2 gene did not show any evidence of somatic mutation, the monoallelic AHCYL2 gene deletion was directly correlated with underexpression of AHCYL2 transcripts, indicating a typical pattern of haploinsufficiency. The precise role of AHCYL2 remains unknown, but some data suggest that the AHCY-like proteins may regulate the activity of AHCY (S adenosylhomocysteine hydrolase) and consequently may affect the methylation metabolism. In addition, we report on a DNMT3A-R882H mutation (1/27, 3.7%) for the first time in SMZL. These findings suggest that methylation pathway dysfunction may play a crucial role in the pathogenesis of SMZL
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Mathot, Sylvie. "Phytoplankton in the marginal ice zone and its contribution to the annual primary production of the Southern Ocean." Doctoral thesis, Universite Libre de Bruxelles, 1993. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212778.
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Dinkler, Karl L. "The variability of the marine atmospheric boundary layer in the Greenland Sea marginal ice zone a case study." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23443.
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Nicoli, Gautier. "The metamorphic and anatectic history of Archaean metapelitic granulites from the South Marginal Zone, Limpopo Belt, South Africa." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97041.
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Thesis (DSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Anatexis is the first step in granite genesis. Partial melting in the lower crust may produce leucoratic features of unusual chemical compositions, very different from the final products of crustal differentiation. Therefore, the links that exists between some migmatites and crustal-derived granites can be ambiguous. This study is an investigation of the anatectic history of a high-grade terrain: the Southern Marginal Zone of the Limpopo Belt (SMZ), north to the Kaapvaal Craton in South Africa. The work involved an integrated field, metamorphic, geochemical and geochronogical study of the metasedimentary granulites from two separate quarries in the northern zone of the Southern Marginal Zone, the Bandelierkop quarry and the Brakspruit quarry, where Neoarchean high-grade partial melting features can be observed. The project has aimed to address two main issues: (1) to accurately constrain the pressuretemperature conditions and the age of the metamorphic episode in the SMZ, with implication for the geodynamic processes near the end of the Archean, (2) to investigate the fluid-absent partial melting reactions that control formation of K2O-poor leucosomes and to understand the chemical relationships in the system source-leucosome-melt–S-type granite. The P-T-t record retained in the Bandelierkop Formation metapelites, constrained by phase equilibria modelling as well as zircon LA-ICP-MS geochronology, gives an insight into crustal differentiation processes in the lower crust. Rocks in both quarries indicate high-temperature metamorphism episodes with peak conditions of 840-860 oC and 9-11 kbar at c. 2.71 Ga with formation of leucosomes (L1) during the prograde path. Minor leucocratic features (L2) were produced during decompression to 6-7 kbar. The end of the metamorphic event is marked by the granulites/amphibolites facies transition (< 640 oC) at c. 2.68 Ga. The maximum deposit age for the detrital zircons in the metapelites (c. 2.73 Ga) indicates a rapid burial process ( 0.17 cm.y1). Those evidences strongly support that the Southern Marginal Zone contains sediments deposited in an active margin during convergence, and that the metapelites were metamorphosed and partially melted as a consequence of continental collision along the northern margin of the Kaapvaal Craton at c. 2.7 Ga. The leucocratic features generated along this P-T-t path display an unusual chemistry with low K2O and FeO+MgO content and high CaO content. The combination of field observations, chemical mapping and geochemical analyses leads to the conclusion the major part of the leucosomes (L1) crystallized prior to syn-peak of metamorphism concurrent with melt extraction from the source. This study documents the details of leucosomes formation using field observations in the Southern Marginal Zone and numerical modelling. This work demonstrates that the formation of K2O-poor leucosome in the metasedimentary lower crust is controlled by the difference in volume of equilibration and heterogeneities within the migmatites. The partial melting of the source coupled with melt loss and water diffusivity within the melt transfer site is a potential mechanism to explain the chemical link in the sytem residuum– melt–S-type granite.
AFRIKAANSE OPSOMMING: Anateksis is die eerste stap in granietgenese. Meganismes wat in die onderste kors aan die werk is, is verantwoordelik vir korsdifferensiasie en bepaal die chemiese samestelling van die graniet. Hierdie studie het’n ondersoek behels van die anatektiese geskiedenis van ’n ho egraadse terrein: die suidelike randstreek van die Limpopo-gordel, noord van die Kaapvaal-kraton in Suid-Afrika. Die werk het ’n ge integreerde veld- , metamorfiese, geochemiese en geochronologiese studie van die metasedimentêre granuliete van twee afsonderlike groewe in die noordelike sone van die suidelike randstreek (SRS), die Bandelierkop-groef en die Brakspruit-groef, waar Neoarge iese ho egraadse gedeeltelike smeltkenmerke waargeneem kan word, ingesluit. Die projek was gerig op die ondersoek van twee belangrike kwessies: (1) om die drukâtemperatuurtoestande en die ouderdom van die metamorfiese episode in die SRS akkuraat te beheer, met implikasie vir die geodinamiese prosesse naby die einde van die Arge ikum, en (2) om die reaksies onder gedeeltelik gesmelte toestande wat die vorming van migmatiete beheer, te ondersoek en die chemiese verwantskappe in die stelsel bron - leukosoom - smelt - S-tipe graniet te begryp. Die P-T-t-rekord wat in die Bandelierkop-formasie metapeliete behoue is, ingeperk deur modellering van fase-ekwilibria asook sirkoon LA-ICP-MS-geochronologie, gee insig in korsdifferensiasieprosesse in die onderste kors. Rotse in albei groewe dui op metamorfismeepisodes teen hoë temperature met piektoestande van 840â860 oC en 9â11 kbar teen ongeveer 2.71 Ga met vorming van leukosome (L1) gedurende die progradeerpad. Geringe leukokratiese eienskappe (L2) het tydens dekompressie tot 6â7 kbar ontstaan. Die einde van die metamorfiese voorval word gekenmerk deur die fasiesoorgang van granuliete / amfiboliete (<640 oC) by ongeveer 2.68 Ga. Die maksimum afsettingsouderdom vir die detitrale sirkone in die metapeliete (ongeveer 2.73 Ga) dui op Å snelle begrawingsproses ( 0.17 cm.y1). Daardie bewyse bied sterk ondersteuning daarvoor dat die SRS sedimente bevat wat gedurende konvergensie in Å aktiewe rand afgeset is, en dat die metapeliete gemetamorfoseer en gedeeltelik gesmelt het as gevolg van kontinentbotsing langs die noordelike rand van die Kaapvaal-kraton teen ongeveer 2.7 Ga. Die leukokratiese eienskappe wat langs hierdie P-T-t-pad opgewek word, toon Å ongewone chemiese samestelling met lae K2O en FeO+MgO-inhoud en ho e CaO-inhoud. Die kombinasie van veldwaarnemings, chemiese kartering en geochemiese ontledings lei tot die gevolgtrekking dat die grootste deel van die leukosome (L1) gekristalliseer het voor die syn-piek van metamorfisme tesame met smeltekstraksie van die bron. Hierdie studie het die besonderhede van leukosoomformasie met behulp van veldwaarnemings in die SRS en numeriese modellering opgeteken. Hierdie werk toon aan dat korsdifferensiasie in die metasedimentêre onderste kors deur Å ander volume van ekwilibrasie en heterogeniteite in die migmatiete beheer word. Die gedeeltelike smelting van die bron gepaard met smeltverlies en waterdiffusiwiteit tot in die smeltoordragterrein is ’n potensiele meganisme om die chemiese skakel in die stelsel residuum-smelt-S-tipe graniet te verklaar.
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Bun, Mylène. "Etude des mécanismes moléculaires induits par l’activation de la voie de signalisation NOTCH2 dans les lymphomes B de la zone marginale de la rate (SMZL) NOTCH-Induced MYC Expression Is Required for Marginal Zone Lymphoma Cell Survival." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL067.
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Le lymphome B de la zone marginale de la rate (SMZL) est un lymphome non-hodgkinien qui touche principalement les sujets âgés (65 ans). Ce type de lymphome de B de la zone marginale se caractérise par une prolifération aberrante des lymphocytes B de la zone marginale de la rate. Cette sur-prolifération entraîne chez les patients une splénomégalie, une cytopénie, une thrombocytose et dans 15% des cas, une manifestation auto-immune. A ce jour, il n’existe aucun traitement spécifique. Des études basées sur les analyses mutationnelles sur les patients ont permis de mettre en évidence une mutation spécifique et récurrente dans 25% des cas, au niveau de la voie de signalisation NOTCH2. Cette mutation est une mutation qui tronque le domaine PEST, indispensable pour la dégradation du domaine intracellulaire de NOTCH2 et donc à l’arrêt de celle-ci. Ainsi, cette mutation somatique gain-de-fonction entraîne une sur-activation de l’activité de NOTCH2 dans les lymphocytes B de la zone marginale de la rate. Les mécanismes moléculaires induits par l’activation de la voie NOTCH2 dans la pathogenèse ne sont pas clairs. Par conséquent, identifier les gènes cibles directs de NOTCH2 pourrait permettre de mieux comprendre les mécanismes moléculaires induits par NOTCH2 et donc permettrait l’établissement d’une thérapie ciblée pour traiter ces patients mutés de la voie NOTCH2. Tout au long de ma thèse, j’ai cherché à identifier les gènes cibles directs de la voie de NOTCH2 induits dans ce type de lymphome B. Dans un premier temps, j’ai caractérisé une lignée cellulaire SMZL : Ri-1. Puis, afin d’identifier les changements transcriptionnels induits par NOTCH2, j’ai effectué un séquençage d’ARN (RNA-seq) sur trois conditions différentes. Ces données nous ont permis d’identifier l’oncogène MYC comme étant potentiellement un gène cible direct de NOTCH2. A côté de cela, afin d’identifier les facteurs épigénétiques associés aux oncogènes, nous avons effectué un crible de shRNA. Nous avons mis en évidence une répression significative de l’expression de MYC dans ces cellules. Afin de confirmer ces résultats et d’identifier le rôle fonctionnel de MYC dans ces cellules, j’ai inhibé l’expression de MYC à l’aide de shRNA. Ces données sont cohérentes avec les résultats du crible, lorsque MYC est inhibé dans ces cellules, cela entraîne une mort cellulaire. Ainsi, nous avons conclu que MYC est requis pour la prolifération et la croissance des cellules cancéreuses. J’ai par la suite, effectué une expérience de complémentation fonctionnelle. J’ai forcé l’expression endogène de MYC grâce à la technologie du CRISPRa dans les conditions où l’activité de NOTCH2 est inhibée. Nous avons mis en évidence une restauration de la survie cellulaire lorsque MYC est exprimé dans les conditions où la voie NOTCH2 est inhibée. Ainsi, cette étude nous a permis de démontrer que l’induction de MYC est essentielle à prolifération, à la croissance et à la survie des cellules cancéreuses. De plus, identifier MYC comme étant un gène cible direct de NOTCH2, nous permet de mieux comprendre les mécanismes moléculaires induits dans la pathogenèse de celui-ciSplenic marginal zone lymphoma (SMZL) is a indoldent B-cell neoplasm lymphoma involving the spleen and bone marrow that affects mostly old people (65 yo). SMZL patients manifest a splenomegaly and a cytopenia. In 15% of the case, autoimmune manifestations are found. Studies based on mutational analysis have highlighted a specific and recurrent mutation in 25% of the case in NOTCH2 signaling pathway. This mutation truncates the PEST domain, which is crucial for NOTCH2 intracellular domain degradation, and so the activation arrest. Hence this somatic gain-of-function mutation leads to an over-activation of NOTCH2 signaling in SMZL. Molecular mechanisms induced by NOTCH2 in the pathogenesis remains unclear. Therefore, identifying NOTCH2 direct target genes may allow establishment of targeted therapies to treat SMZL patients mutated in NOTCH2 signaling. All along my PhD study, I aimed to identify NOTCH2 direct target genes induced in SMZL. First, I characterized Ri-1 cell line as a relevant cell model for my study. Then, to identify transcriptional changes induced by NOTCH2 in SMZL, RNA-seq was performed. From these data, among genes that were significantly re-expressed, I identified the oncogene MYC as a potential NOTCH2 direct target gene. Beside, to probe epigenetic factors associated with oncogenes, ShRNA screen was performed. We have highlighted that MYC expression was significantly repressed. To confirm these data, MYC depletion was done using ShMYC. These data are consistent with the shRNA screen data. When MYC expression is repressed, there is a significant decrease of cell proliferation and growth. To validate these data, an MYC-independent NOTCH2 expression was endogenously induced using CRISPRa technology in the condition where NOTCH2 activity is inhibited. We have demonstrated that MYC –independent NOTCH2 expression restores cancer cell survival when NOTCH2 activity is repressed. Hence, in this study, I showed that MYC expression is required for cell growth, cell proliferation and cell survival. Moreover, identifying MYC as a potential NOTCH2 direct target gene allows a better understanding of molecular mechanisms induced in SMZL pathogenesis
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Kolan, Shrikant S. "Defining the role of CD47 and SIRPα in murine B cell homeostasis." Doctoral thesis, Umeå universitet, Institutionen för integrativ medicinsk biologi (IMB), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-107636.
Full textAbstract:
B cell development is a highly organized process, which commences in the fetal liver during embryogenesis and in the bone marrow (BM) after birth. Surface IgM+ immature B cells emigrate from the BM via the blood stream to the spleen and finally differentiate into conventional mature follicular B (FoB) cells and marginal zone (MZ) B cells. Conversely, some sIgM+ immature B cells can also mature into IgD+ FoB cells in the BM. The ubiquitously expressed cell surface glycoprotein CD47 and its receptor signal regulatory protein α (SIRPα) are members of the immunoglobulin superfamily. Both individually and upon their interaction, CD47 and SIRPα have been found to play important role in the homeostasis of T lymphocytes or CD8 conventional dendritic cells (cDCs) in secondary lymphoid organs. However, their role in regulating B cell homeostasis has remained unknown. The present study describes important roles of CD47 and SIRPα in B cell homeostasis. Lack of SIRPα signaling in adult SIRPα mutant (MT - cytoplasmic domain deletion) mice resulted in an impaired B cell maturation in the BM and spleen, which was also reflected in the blood. In the BM and spleen of SIRPα MT mice, reduced numbers of semi-mature IgD+IgMhi follicular type-II (F-II) and mature IgD+IgMlo follicular type-I (F-I) B cells were observed, while earlier BM B cell progenitors or splenic transitional B cells remained unaltered. In SIRPα MT mice, maturing B cells in BM and spleen were found to express higher levels of the pro-apoptotic protein BIM and contained an increased level of apoptotic cells. In contrast to that for FoB cells, the splenic MZ B cell population was increased with age in SIRPα MT mice without showing an increased level of activation markers. Immunohistochemical analysis revealed an increased follicular localization of MZ B cells in the spleens of SIRPα MT mice. In addition, MZ macrophages and marginal metallophilic macrophages were not restricted to their normal position in SIRPα MT spleens. Interestingly, CD47-deficient (CD47-/-) mice mimicked the FoB cell phenotype observed in SIRPα MT mice and had a reduced number of FoB cells in the BM, blood and the spleen at 56 months of age, but not in younger mice. Similar to SIRPα MT mice, CD47-/- mice also displayed an increased number of splenic MZ B cells. Sera form both mouse strains did not show any signs of an increased production of autoantibodies or antinuclear antigens. BM reconstitution experiments identified a requirement for non-hematopoietic SIRPα signaling for normal B cell maturation in the BM and to maintain normal numbers and retention of MZ B cells in the splenic MZ. On the contrary, hematopoietic SIRPα signaling appeared to be important for FoB cell maturation in the spleen. Interestingly, hematopoietic SIRPα was required for normal MZ retention of MZ macrophages while normal distribution of metallophilic macrophages required nonhematopoietic SIRPα signaling. Collectively, these findings revealed an important role of CD47 and of SIRPα signaling in B cell homeostasis in different lymphoid organs.
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Sebetlela, Teboho. "Tectonometamorphic evolution of Medium-P granulites of the Namaqua Metamorphic Province at the Gordonia Subprovince marginal zone, southern Namibia." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25405.
Full textAbstract:
The western Namaqua Metamorphic Complex (NMC) is a Mesoproterozoic mediumto low-pressure, high temperature metamorphic belt that is characterised by a complex, polyphase Mesoproterozoic metamorphic history. Using an integrated approach, the P-T-t evolution of a portion of the marginal zone between two major tectonic domains in the western NMC: the Richtersveld and Gordonia Subprovices is investigated, with the aim of resolving a P-T-t path for the peak to retrograde evolution of a major regional thrust, that will in turn help to elucidate its geodynamic significance. The Kum Kum Klippe represents a structural outlier of the Gordonia Subprovince, located at the frontal zone of the Grunau Terrane, where the Grunau Terrane (hangingwall), Pella Terrane (footwall) and the bounding Lower Fish River Thrust Zone (LFRTZ) are all well exposed. The Pella Terrane in this region shows signi ficant lithological heterogeneity and is constituted by felsic orthogneisses, metama fic rocks and leucogranite intrusives, while the Grunau Terrane is dominated by pelitic granulites. The LFRTZ along the southwestern margin of the Kum Kum Klippe is a ~30-40 m wide tabular zone primarily localised in the Pella Terrane. Phase equilibria modelling of pelitic granulites from the hangingwall constrains peak metamorphic P-T conditions of ~5.2-5.9 kbar and ~790-815°C which are correlated to a monazite growth event at c. 1262-1184 Ma. Sheared pelitic granulites constrain the P-T conditions for early stage shearing in the LFRTZ to ~2.8-5.0 kbar and ~640-785°C which likely occurred shortly after peak metamorphism. Pella amphibolite samples from the footwall and LFRTZ constrain the conditions of tectonic juxtaposition to ~2.7 kbar and ~542°C which must have occurred subsequent to cooling from suprasolidus conditions and is thus constrained at <1184 Ma. The constrained peak to retrograde P-T-t path is characterised by a short segment of substantial decompression subsequent to peak metamorphic conditions at c. 1262-1184 Ma. This is followed by a period dominated by cooling with only a small component of concomitant decompression, which together with the early decompressive segment likely correspond to the period of retrograde shearing, which ultimately led to tectonic juxtaposition in the mid-amphibolite facies at c. <1184 Ma. The P-T path presented suggests that the LFRTZ does not represent a terrane bounadry that juxtasposes crustal entities which converged and collided as the result of Wilson cycle subduction to collision tectonics. Contrastingly the metamorphism at highly elevated geotherms and largely cooling dominated retrograde trajectory determined in this study are more compatible with a continental backarc setting, which has recently been proposed as an alternative model. Thus the P-T constraints presented in this study contradict the collisional model and terrane concept that has long been widely accepted for the western NMC.
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De, Kock Wade. "The Marginal Ice Zone (MIZ) seawater property dynamics of the Southern Ocean below Southern Africa using animal-borne observations." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29614.
Full textAbstract:
The Marginal Ice Zone (MIZ) in the Southern Ocean is a dynamic area shown to vary seasonally in width and extent northward. Remote sensing is the only tool available to give a large-scale picture of sea-ice conditions but it is important to note that only surface properties are visible in remote sensing products. Little is known about the hydrographical properties of the Atlantic Sector of the Southern Ocean in the austral winter as it is difficult to obtain shipboard observations. Using observations from southern elephant seals, it is possible to analyse properties such as salinity and temperature within the MIZ. These properties may then be related to observations of sea ice concentration obtained by remote sensing to qualitatively describe their relationships. This work provides an example of how data from selected seal observations and satellite data can be used operationally to define the hydrography of the MIZ, focusing on the years 2005 to 2009. Results show that the properties of the underlying water in the MIZ appear to be fairly constant in the region of 15°W to 45°E for the months of July and August. A warmer pool of water is evident in the east of this region. Based on what is known about the physics of the region and what is seen spatially regarding changes in temperature and salinity, the warm pool may be brought about by eddies along the South West Indian Ridge. Results also show that surface concentrations of sea ice may have an effect on the underlying properties of the water. A more detailed description of the characteristics and features in the MIZ may further help to understand key processes in the region. Changes in subsurface temperature and salinity may influence the formation of ice. This may in turn influence large to mesoscale processes in both the ocean and atmosphere. Understanding how these physical properties change and what may cause them to change can help further understanding of larger scale processes.
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Beattie, Lynette. "The role of the spleen in Malaria : Cellular changes that affect the development of immunity." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16195/1/Lynette_Beattie_Thesis.pdf.
Full textAbstract:
Malaria, caused by the apicomplexan parasite Plasmodium, is a major cause of morbidity and mortality throughout the world. This study has focused on the role of the spleen in the control of the blood stage of infection. Three aspects have been examined specifically: the effect of infection on the architecture of the spleen, the role of the spleen in parasite clearance and the formation of B cell memory.
Firstly, the effect of infection on the splenic microarchitecture was examined. An
essential component of the splenic architecture is the marginal zone (MZ), an area of the spleen that separates the reticuloendothelial red pulp of the spleen from the lymphoid white pulp compartment. Two unique populations of macrophages are
found in the marginal zone: marginal zone macrophages (MZM) and marginal metallophilic macrophages (MMM). In the current study, parasitised red blood cells (pRBC) as well as normal RBC located to the MZ thirty minutes after intravenous injection and formed close associations with both MMM and MZM. Eight days after infection, at the time of peak parasitemia, a complete loss of both MMM and MZM was observed. Assays to detect cell death revealed that the loss of both MMM and MZM appeared to occur as a result of apoptosis. The apoptosis was not induced by
up regulation of the inflammatory cytokines tumour necrosis factor or interferon-γ
and could not be blocked by over expression of the apoptosis inhibitor Bcl2. Significantly, MMM were retained in the absence of CD8+ T cells implicating CD8+
T cells in the loss of MMM. Finally, infection of CD95-/- mice demonstrated that
CD95/CD95-ligand (Fas/Fas-ligand) interactions were responsible for some of the CD8+ T cell-mediated loss of MMM. These data provide evidence for a novel interaction between MMM and CD8+ T cellsfollowing infection with Plasmodium.
Secondly, the role of the spleen in the control of parasitemia and disease was
monitored with an emphasis on determining the role of splenic macrophage populations (MMM, MZM and red pulp macrophages [RPM]) in parasite clearance.
A clodronate liposome-mediated macrophage depletion technique was used, and caused a complete loss of all three macrophage sub-populations, as well as 50% of splenic dendritic cells, within 24 hours of administration. Each of the macrophage
populations, as well as splenic DC, demonstrated different repopulation kinetics following their depletion from the spleen and these kinetics were utilised to examine
each cell population in isolation. RPM depleted mice had significantly higher peak
parasitemias than the controls. This peak returned to the level observed in undepleted control animals only after the repopulation of RPM was complete, suggesting that RPM play a role in the control of peak parasitemia following infection. Neither MMM nor MZM played a role in the control of parasitemia. The role of non-splenic macrophages and splenic dendritic cells also was investigated and shown to be insignificant in the absence of splenic macrophages. Finally, the role of RPM in mice immune to infection was investigated and their role shown to be dispensable, with immune mice clearing parasitemia efficiently in the absence of RPM. RPM therefore are important for the innate control of infection with P. chabaudi but are dispensible once adaptive immunity is established.
Finally, the role of the spleen in the development of parasite-specific B cell memory was examined. Initial studies demonstrated that germinal centre (GC) development was compromised following infection with P. chabaudi, with an involution of B cell follicles noted early in infection. Adoptive transfer of memory B cells from immunised to naïve mice demonstrated that some protection was conferred on recipient mice by parasite-specific memory B cells. But, the memory B cells could not protect the host from developing parasitemia and did not produce significant amounts of parasite-specific immunoglobulin within seven days of challenge infection. Memory B cells could not be detected ten weeks after infection, indicating that the development, or survival, of parasite-specific memory B cells was compromised. The development of bystander memory B cells was not affected by
infection. Finally, long-lived plasma cells were shown to develop in response to
infection, although re-exposure of the cells to parasites in the form of recrudescent
parasitemia resulted in their loss. This study therefore has identified a defect in the development of long-term, B cell-mediated, protection against infection with P. chabaudi.
Each of these factors has significant implications for the understanding of how the spleen contributes to the control of infection with Plasmodium and potential
applications for the further development of malaria vaccines and treatment regimens.
38
Beattie, Lynette. "The role of the spleen in Malaria : Cellular changes that affect the development of immunity." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16195/.
Full textAbstract:
Malaria, caused by the apicomplexan parasite Plasmodium, is a major cause of morbidity and mortality throughout the world. This study has focused on the role of the spleen in the control of the blood stage of infection. Three aspects have been examined specifically: the effect of infection on the architecture of the spleen, the role of the spleen in parasite clearance and the formation of B cell memory. Firstly, the effect of infection on the splenic microarchitecture was examined. An essential component of the splenic architecture is the marginal zone (MZ), an area of the spleen that separates the reticuloendothelial red pulp of the spleen from the lymphoid white pulp compartment. Two unique populations of macrophages are found in the marginal zone: marginal zone macrophages (MZM) and marginal metallophilic macrophages (MMM). In the current study, parasitised red blood cells (pRBC) as well as normal RBC located to the MZ thirty minutes after intravenous injection and formed close associations with both MMM and MZM. Eight days after infection, at the time of peak parasitemia, a complete loss of both MMM and MZM was observed. Assays to detect cell death revealed that the loss of both MMM and MZM appeared to occur as a result of apoptosis. The apoptosis was not induced by up regulation of the inflammatory cytokines tumour necrosis factor or interferon-γ and could not be blocked by over expression of the apoptosis inhibitor Bcl2. Significantly, MMM were retained in the absence of CD8+ T cells implicating CD8+ T cells in the loss of MMM. Finally, infection of CD95-/- mice demonstrated that CD95/CD95-ligand (Fas/Fas-ligand) interactions were responsible for some of the CD8+ T cell-mediated loss of MMM. These data provide evidence for a novel interaction between MMM and CD8+ T cellsfollowing infection with Plasmodium. Secondly, the role of the spleen in the control of parasitemia and disease was monitored with an emphasis on determining the role of splenic macrophage populations (MMM, MZM and red pulp macrophages [RPM]) in parasite clearance. A clodronate liposome-mediated macrophage depletion technique was used, and caused a complete loss of all three macrophage sub-populations, as well as 50% of splenic dendritic cells, within 24 hours of administration. Each of the macrophage populations, as well as splenic DC, demonstrated different repopulation kinetics following their depletion from the spleen and these kinetics were utilised to examine each cell population in isolation. RPM depleted mice had significantly higher peak parasitemias than the controls. This peak returned to the level observed in undepleted control animals only after the repopulation of RPM was complete, suggesting that RPM play a role in the control of peak parasitemia following infection. Neither MMM nor MZM played a role in the control of parasitemia. The role of non-splenic macrophages and splenic dendritic cells also was investigated and shown to be insignificant in the absence of splenic macrophages. Finally, the role of RPM in mice immune to infection was investigated and their role shown to be dispensable, with immune mice clearing parasitemia efficiently in the absence of RPM. RPM therefore are important for the innate control of infection with P. chabaudi but are dispensible once adaptive immunity is established. Finally, the role of the spleen in the development of parasite-specific B cell memory was examined. Initial studies demonstrated that germinal centre (GC) development was compromised following infection with P. chabaudi, with an involution of B cell follicles noted early in infection. Adoptive transfer of memory B cells from immunised to naïve mice demonstrated that some protection was conferred on recipient mice by parasite-specific memory B cells. But, the memory B cells could not protect the host from developing parasitemia and did not produce significant amounts of parasite-specific immunoglobulin within seven days of challenge infection. Memory B cells could not be detected ten weeks after infection, indicating that the development, or survival, of parasite-specific memory B cells was compromised. The development of bystander memory B cells was not affected by infection. Finally, long-lived plasma cells were shown to develop in response to infection, although re-exposure of the cells to parasites in the form of recrudescent parasitemia resulted in their loss. This study therefore has identified a defect in the development of long-term, B cell-mediated, protection against infection with P. chabaudi. Each of these factors has significant implications for the understanding of how the spleen contributes to the control of infection with Plasmodium and potential applications for the further development of malaria vaccines and treatment regimens.
39
Sakakibaya, Ayako, Kumi Kawai, Tetsuro Nagasaka, Shigeo Nakamura, 芳江 下山, 綾子 榊原, 久美 川井, and 徹郎 長坂. "Molecular diagnosis of malignant lymphoma : mantle cell lymphoma, anaplastic large cell lymphoma, and marginal zone B-cell lymphoma of malt." Nagoya University School of Medicine, 2006. http://hdl.handle.net/2237/6127.
Full text
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Tavhelidse, Tinatini [Verfasser], and Joachim [Akademischer Betreuer] Wittbrodt. "The role of rx genes in establishment and maintenance of the medaka ciliary marginal zone / Tinatini Tavhelidse ; Betreuer: Joachim Wittbrodt." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1182993524/34.
Full text
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Meyer, Albrecht H. H. [Verfasser]. "Transformation and additional malignancies are leading risk factors for an adverse course of disease in marginal zone lymphoma / Albrecht H.-H. Meyer." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2015. http://d-nb.info/1079841113/34.
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Barra, Quaglia Carolina M. 1982. "Sinusoid-lining cells are novel myeloid-endothelial innate cells that form splenic niches for marginal zone B cell activation and plasma cell survival." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/328415.
Full textAbstract:
Los sinusoides del bazo humano promueven la lenta percolación de la
sangre, favoreciendo la captura de antígeno por los fagocitos y
linfocitos del sistema inmune local. Estratégicamente posicionadas
delimitando los vasos, e históricamente conocidas como células
retículo-endoteliales, las células que delinean los sinusoides (SLCs),
tienen una biología enigmática y podrían ser vistas como un
componente desconocido del sistema inmunológico. En esta tesis
hemos observado que las SLCs poseían un fenotipo simil-endotelial,
eran específicas de humano y expresaban moléculas típicamente
asociadas al linaje endotelial como el factor de von Willenbrand, y las
moléculas CD31, CD54, CD102, CD105 y CD141. Sin embargo, a
diferencia de las células endoteliales, las SLCs también expresaban
moléculas típicamente asociadas al linaje estromal como la vimentina y
la actina de músculo liso, junto con varias moléculas del linaje mieloide
como CD14, CD36, CD163, MR, DEC-205 y TLR4. A si mismo, las
SLCs evidenciaron una huella genética típicamente macrofágica que
incluía sensores microbianos, receptores de tipo “scavenger”,
mediadores de la respuesta inmunitaria y reguladores de la fagocitosis y
la presentación antigénica. Además de fagocitar antígenos a través de
un mecanismo actina-dependiente, las SLCs secretaban BAFF, APRIL,
IL-6 y CXCL10, induciendo el reclutamiento, la activación y la
supervivencia de células B de la zona marginal, un subtipo celular
especializado en la respuesta de anticuerpos frente a antígenos
provenientes de la sangre. Por lo tanto, las SLCs son células endoteliomieloides
que funcionan como centinelas dotados de funciones
fagocíticas y que ayudan en la producción de anticuerpos.Sinusoid vessels promote the slow percolation of venous blood through the red pulp of the spleen, thereby favoring antigen capture by phagocytes and lymphocytes of the local immune system. Strategically positioned around sinusoids and historically known as reticulo-endothelial cells, sinusoid-lining cells (SLCs) have an enigmatic biology and thus can be viewed as an orphan component of our immune system. We found here that SLCs were a human-specific population of endothelial-like cells that expressed typical endothelial molecules such as von Willenbrand factor, CD31 (PECAM-1), CD54 (ICAM-1), CD102 (ICAM-2), CD105 (endoglin) and CD141 (thrombomodulin). However, unlike endothelial cells, SLCs also expressed the stromal molecules vimentin and smooth muscle actin along with several myeloid molecules such as CD14, CD36, CD163, MR, DEC-205 and TLR4. Accordingly, SLCs showed a prominent macrophage-like gene signature that included microbial sensors, scavanger receptors, immune mediators, and regulators of phagocytosis and antigen presentation. Besides phagocytosing particulate antigens through an actin-dependent mechanism, SLCs released BAFF, APRIL, IL-6 and CXCL10, which enhanced the recruitment, activation and survival of marginal zone (MZ) B cells, a splenic lymphocyte subset specialized in innate-like antibody responses to blood-borne antigens. Thus, SLCs are endothelialmyeloid cells that serve as sentinels endowed with phagocytic and antibody-enhancing functions.
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Gobel, Teresa M. "Aircraft observations of the atmospheric boundary layer in the vicinity of the marginal ice zone under conditions of flow parallel to the ice edge." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241072.
Full textAbstract:
Thesis (M.S. in Meteorology and Oceanography)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Shaw, W.J. Second Reader: Nuss, W.A. "September 1990." Description based on title screen as viewed on December 29, 2009. DTIC Identifier(s): Marine atmospheres, marginal ice zones, geostropic wind, atmospheric boundary layer, stratus clouds, cumulus clouds, stratocumulus clouds, wind velocity, temperature inversion, air ice interactions. Author(s) subject terms: Marginal ice zone. Includes bibliographical references (p. 45-46). Also available in print.
44
Wulff, Thorben Verfasser], Antje [Akademischer Betreuer] [Gutachter] [Boetius, and Oliver [Gutachter] Zielinski. "Physics and Ecology in the Marginal Ice Zone of the Fram Strait : a Robotic Approach / Thorben Wulff ; Gutachter: Antje Boetius, Oliver Zielinski ; Betreuer: Antje Boetius." Bremen : Staats- und Universitätsbibliothek Bremen, 2015. http://d-nb.info/1119290643/34.
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Scott, Catherine Louise. "Calanoid copepods and ice fauna in Arctic fjords and regions of the marginal ice zone around Svalbard : lipids; stage distributions; trophic interactions and life strategies." Thesis, University of Stirling, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341210.
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Alyafei, Saud Abdalla Mubarak Mohamed. "Study of the reactivity of a monoclonal antibody that recognises human marginal zone B cells and a subset of germinal centre cells in tissue sections." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/study-of-the-reactivity-of-a-monoclonal-antibody-that-recognises-human-marginal-zone-b-cells-and-a-subset-of-germinal-centre-cells-in-tissue-sections(7fcf0edc-b729-4215-ae52-a9e2d2622493).html.
Full textAbstract:
Marginal Zone (MZ) cells are a subset of B cells. They reside the marginal zone outside the mantle zone of the spleen and circulate the blood in humans. They have also been identified in the crypt epithelium of tonsil, the sub-capsular sinus in lymph node and in the dome area of Peyer’s patches in gut-associated lymphoid tissue of human intestine. A monoclonal antibody (4D12) that recognises an antigen on MZ B cells and a subset of GC cells in tissue sections has been described previously but this has not been investigated in detail and features of the 4D12 antigen and the lymphocytes that express it are unknown. The re-establishment and culture of the 4D12 MoAb secreting clone after a long-term storage is described. A method to analyse the distribution of 4D12 antigen on subsets of B cells was devised. Subsets expressing 4D12 antigen included CD27+IgM+IgD+ cells, CD27+IgM+IgD- cells, transitional B cells and plasmablasts. Lower expression by mature naïve and class switched memory B cells was observed. 4D12 MoAb tended to recognise a greater proportion of CD27+IgM+IgD+ cells and CD27+IgM+IgD- cells in spleen compared to tonsil and blood. Intracellular staining showed that the 4D12 antigen is proportionally more presented in the cytoplasm than the cell surface and that cytoplasmic 4D12 antigen expression is not restricted to B cells. The identity of the antigen was sought by western blotting and mass spectrometry (by collaborators) and the output of the mass spectrometry was provided for this study. Mass spectrometry data was analysed here and a list of candidates for the identity of 4D12 antigen were selected and tested by flow cytometry.
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Vennemann, Torsten Walter. "A geochemical and stable isotope study of some rocks from the Bandelierkop formation, southern marginal zone of the Limpopo Belt, South Africa( vol.1 Text)." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/23476.
Full textAbstract:
The Bandelierkop Formation of the Southern Marginal Zone (SMZ) of the Limpopo Belt consists of metamorphosed ultramafic, mafic and sedimentary rocks. Metamorphic conditions indicated by the petrography of these different rock groups are consistent with upper amphibolite to granulite facies. The ultramafic and mafic rocks are geochemically akin to peridotitic-pyroxenitic intrusive rocks and high-Mg basalts respectively. Metamorphism of these two rock groups in the SMZ was an essentially closed system process, except for the highly volatile phases such as H₂O and CO₂. The metasediments appear to represent a sequence of high (Mg+Fe)-greywackes and/or deep-water shales with minor amounts of iron formation material. The unusually mafic character of the metasediments can be ascribed to a high ultramafic + mafic source component to the original sediment. Some modification of the major and trace element compositions of the pelitic rocks has been caused by the removal of partial melts and the metamorphism of the pelitic rocks is not therefore considered to have occurred under closed system conditions. Variable extraction of partial melts is implied by the chemical variations shown by the pelitic rocks and is also suggested by the presence of large pegmatitic felsic bodies which are commonly found close to the pelitic rocks. Detailed petrographic study of the Bandelierkop Formation rocks suggests an increase in metamorphic grade, and/or a decrease in water activity, from south to north within the Southern Marginal Zone. Peak metamorphic conditions of 730°C + 65°C at pressures of 6.1 ± 1.5 kbars may be deduced from a careful application of several cation thermometers and barometers on selected mineral analyses. A rigorous application of garnet-biotite thermometry to the pelitic rocks indicates that the transition from orthoamphibole gneisses in the south to orthopyroxene-bearing rocks in the north of the SMZ terrane, is a function of changing biotite composition and/or decreasing water activities rather than an increase in metamorphic temperatures. In contrast to the major and trace element data, the stable isotope data for the ultramafic and mafic rocks in the SMZ indicate open system behaviour for some of these rocks, but closed system behaviour for the pelites. Extraction of SO to 70% partial melts from the pelitic rocks, should not, however, have affected the δ¹⁸O value of the restite. Petrological and stable isotope data in the SMZ rocks are consistent with retrogression in all these rocks and open system behaviour for oxygen in some ultramafic and mafic rocks, being caused by the crystallization and accompanying fluid release of melts produced during prograde metamorphism of the pelitic rocks. Small scale (-5 to 30m's) heterogeneity is implied by both oxygen and carbon stable isotope compositions of closely spaced rock samples, even for those collected from within large "shear zones", suggesting small fluid/rock ratios for most of the samples in the high-grade terrane or heterogeneous stable isotopic compositions of the fluids. Furthermore, a similarity in mineral-mineral stable isotope fractionation factors is observed for all the pelitic rocks, including the orthoamphibole gneisses found immediately south of the orthopyroxene isograd. These features preclude the presence of pervasive fluid infiltration after peak metamorphism. Two implications are, that granulite facies metamorphism in the SMZ terrane was not caused by an influx of mantle derived CO₂-rich fluid and, that the orthoamphibole gneisses are not retrogressed equivalents of the granulites found to the north of the orthopyroxene isograd. It is suggested that this isograd represents a change in the water activities of the rocks during metamorphism. Apparent disequilibria in mineral - mineral stable isotope fractionations observed amongst different minerals within any one pelitic rock, may be explained by a combination of the crystallization of residual melt within these rocks and oxygen diffusion amongst minerals which have not reached their oxygen-closure. The concordant quartz-plagioclase, quartz-biotite and plagioclase-biotite oxygen isotope equilibration temperatures are taken to represent minimum crystallization temperatures for the melts (-560°C), while successively higher quartz-orthopyroxene, quartz-amphibole and quartz-garnet oxygen isotope equilibration temperatures are a function of increasing closure temperatures for the orthopyroxene, amphibole and garnet respectively. The minimum estimate to peak metamorphic temperatures is given by the quartz-garnet oxygen isotope temperature averaging 736 + 52°C. If oxygen diffusion experiments performed in hydrothermal systems are appropriate for the SMZ rocks, then cooling rates for the SMZ terrane could have been as low as 12 to 25°C/My over a temperature range of 480 to 600°C. Stable isotope modeling of hypothetical fluids that may have been in equilibrium with the high-grade rocks, suggests that a mixture of CO₂ and H₂O, with CO₂/H₂O mole ratios > 0.1 can precipitate both quartz and carbonate of stable isotope composition similar to those determined for quartz and carbonate from the mineralized Archaean lode gold deposits of the Murchison and Pietersburg greenstone belts. A model involving granulite facies metamorphism, partial melt extraction and subsequent release of fluids, Au, K and S upon crystallization of such melts, appears to be viable for gold mineralization occuring in the adjacent lower grade greenstone belts and in the high-grade terrane of the Southern Marginal Zone.
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Tawadros, Fady, Sakshi Singal, Maria Zayko, and Devapiran Jaishankar. "Mucosal Associated Lymphoid tissue of the Skin, A Common Entity in a Rare Location." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/55.
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Marginal zone (MZ) lymphomas (MZLs) represent a group of lymphomas originating from B lymphocytes of the “marginal zone” which is the external part of the secondary lymphoid follicles. The WHO classifies MZL into 3 entities; extranodal MZL, splenic MZL and nodal MZL. Extranodal marginal zone lymphoma (EMZL) can arise in different tissues, including the stomach, salivary gland, lung, small bowel, thyroid, ocular adnexa and skin. We present a 25 years old female with a history of angioedema and chronic cutaneous eczema who developed an unusual EMZL. Patient presented with a history of rapidly enlarging skin nodule on her left elbow that had been present for almost one year. Over a period of 2-3 weeks she felt the nodule rapidly changed in size and shape. Excisional biopsy of the mass revealed a lymphoid infiltrate based in the reticular dermis and focally extending into the subcutaneous adipose tissue with formation of disrupted lymphoid follicles positive for CD20, CD23 and BCL2 but negative for CD10, Cyclin D1 and SOX11. Diagnosis was consistent with extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Patient on presentation did not have any B symptoms other cutaneous lesions, lymphadenopathy or hepatosplenomegaly. PET scan revealed no evidence of abnormal uptake leading to a final Stage IE definition. Patient initiated definitive radiation therapy. EMZL accounts for 5 -10 % of non-Hodgkin lymphoma. It has been described often in organs that are normally devoid of germinal centers. It may arise in reactive lymphoid tissue induced by chronic inflammation in extranodal sites. Primary cutaneous marginal zone lymphoma (PCMZL) is associated with infectious etiologies such as Borrelia burgdorferi and less commonly with viral infections or in relation to autoimmune disorders. Autoimmune disorders, specifically Sjögren's syndrome is associated with a 30-fold increased risk of marginal zone lymphoma. Localized disease can be treated by local radiotherapy, intralesional injections or excision. Widespread skin disease is usually treated with a CD20 directed monoclonal antibody-Rituximab. Patients with PCMZL usually have an indolent clinical course. Extracutaneous dissemination of MALT Lymphoma is uncommon and happens in 6-8 % of patients. The 5 years overall survival is between 98-100%. Family physicians and dermatologists should have a high index of suspicion for this rare lymphoma subtype especially in patients with inflammatory chronic skin conditions and atopy.
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Möller, Eva Katharina [Verfasser], and Joachim [Akademischer Betreuer] Wittbrodt. "Modulation of the Wnt pathway at single-cell level uncovers diverging functional domains in the ciliary marginal zone of medaka / Eva Katharina Möller ; Betreuer: Joachim Wittbrodt." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1180985761/34.
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Groters, Douglas J. "The temporal and spatial variability of the marine atmospheric boundary layer and its effect on electromagnetic propagation in and around the Greenland Sea marginal ice zone." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23422.
Full textAbstract:
Approved for public release; distribution is unlimitedVariability of the MABL and its effect on the electromagnetic (EM) refractive structure around the Greenland Sea marginal ice zone were examined. Rawinsonde profiles and surface observations collected from 3 ships during MIZEX-87(20 March-11 April) served as the data set. A program, developed to calculate the refractivity at each vertical level of the rawinsonde profiles, also identified the levels at which trapping, superrefraction and subrefraction occurred. Temporal studies showed that a higher incidence of anomalous refractive layers occurred during periods when the region was under the influence of high pressure. More than 50% of the time, trapping and super-refractive layers were attributed to development of a capping inversion just above the MABL during these periods. Spatial studies showed that the refractive structure varied relative to distance from the ice edge as did the depth of the MABL. An upward slope in refractive layer heights was observed from the ice toward the open water. Significant spatial inhomogeneity was observed over horizontal ranges of less than 100 km. This was attributed to both the large-scale synoptic forcing affecting the region and to variations in the surface fluxes of heat and moisture over the ice and over the water. A range-dependent ray trace model developed at the Naval Ocean Systems Center was used to show how the ray paths of EM waves vary with a changing refractive structures. Keywords: Air water interactions, Greenland Sea, Atmospheric refraction, Electromagnetic wave propagation, Heat flux, Sea ice. Theses. (EDC)
http://archive.org/details/temporalspatialv00grot
Lieutenant, United States Navy