Dissertations / Theses on the topic 'LLT1'

Receptor-ligand pairs of C-type lectin-like proteins have been shown to orchestrate and modulate immune responses within particular immune cell subsets or in distinct body locations. The function of CD161 and Lectin-Like Transcript 1 (LLT1) has not been extensively studied, partially due to the lack of validated anti-LLT1 antibodies. Here, I characterised two novel anti-LLT1 monoclonal antibodies (2H7 and 7G7). Using them for flow cytometric and immunohistological staining, I characterised the expression of LLT1 in different healthy human tissues and found that LLT1 levels were particularly high in immune-privileged sites. Germinal centres (GC) are microanatomical structures that are critical for the development of high-affinity antibodies and B cell memory. They are organised into two zones, light and dark, with coordinated roles controlled by local signalling. LLT1 protein is known to be expressed on B cells, but its functional role in the GC reaction has not been explored. I found high expression of LLT1 on GC-associated B cells, early plasmablasts and GC- derived lymphomas. LLT1 expression was readily induced via BCR, CD40 and CpG stimulation on B cells. Ubiquitous expression of CD161 on Follicular Dendritic Cells (FDCs) was revealed, as well as on a subset of T follicular cells. Triggering of LLT1 supported B cell activation, CD83 upregulation and Chemokine (C-X-C Motif) Receptor 4 (CXCR4) downregulation, which is consistent with a role in drivingtransition from a dark to a light zone phenotype. Overall, these data suggest that LLT1-CD161 interactions play a novel and important role in B cell maturation within the GC in humans. A deep understanding of the GC reaction and the process of B cell selection could provide invaluable knowledge into effective vaccine design, generation of auto-antibodies and malignant transformation.

Estudos prévios sugerem que a laserterapia de baixa potência (LLLT) favorece o reparo ósseo perimplantar. Este estudo avaliou a influência da LLLT sobre o reparo ósseo perimplantar in vivo em 32 coelhos Nova Zelândia submetidos à exodontia do incisivo inferior esquerdo imediatamente seguida pela inserção de um implante osseointegrável. Os animais foram distribuídos aleatoriamente em quatro grupos: um grupo controle C (animais não irradiados) e três experimentais. Estes receberam 7 sessões de terapia laser (AsGaAl, infravermelho, 830 ηm, 50mW, CW), com intervalos de 48 horas. A dose de laser por sessão variou entre os grupos EI (10 J/cm²), EII (5 J/cm²) e EIII (20J/cm²). Os animais foram mortos e os espécimes preparados histologicamente para análise da superfície de contato entre osso e implante (BIC) e da área de neoformação óssea entre as espiras (BA), em esteriologia e Microscopia Eletrônica de Varredura (MEV). A concentração de cálcio na interface do tecido ósseo com o implante foi analisada por espectrometria de raios-X por dispersão de energia (EDS). Os resultados foram analisados estatisticamente. Para MEV, as médias de BIC foram significativamente maiores para os grupos EI (977,9 μm) e EIII (1021,1 μm), comparados a EII (761,5 μm) e C (807,8 μm). Em BA, EIII (122573,7 μm²) superou os valores de neoformação dos demais grupos. O EDS para concentração de cálcio não apresentou diferença entre os grupos. A análise de BIC por meio de esteriologia mostrou valores significativamente maiores para EIII (1045,3 μm) em relação aos demais grupos. Para a BA, os grupos EI (100068,3 μm²) e EIII (103934,5 μm²) mostraram grandezas significativamente maiores. O uso da LLLT, no protocolo descrito, influenciou positivamente o reparo ósseo perimplantar com aumento do contato do tecido ósseo com o implante principalmente na dose de 20 J/cm² por sessão, bem como maior volume ósseo neoformado entre as espiras.
Previous studies suggest that the low level laser therapy (LLLT) has a favorable effect on perimplant bone healing. This study evaluates the LLLT influence over perimplant bone healing pattern in 32 New Zealand male rabbits which were subimitted to a lower incisor extraction followed by an osseointegrated implant immediated insertion. The animals were randomly divided into four groups of eight animals each: a control group C (non-irradiated animal) and three experimental groups. They received seven laser therapy sessions (GaAlAs, infrared, 830 nm, 50 mW, CW), every 48 hours. The LLLT per session dose ranged between the groups EI (dose – 10 J/cm²), EII (dose – 5 J/cm²) and EIII (dose – 20 J/cm²). The animals were killed and the specimens received histological preparation for bone implant contact analysis (BIC) and Bone Area evaluation (BA) among the implant threads, both steriology and Scanning Electron Microscopy (SEM). The calcium concentration in bone implant interface were analysed by Energy-Disperse X-Ray Spectroscopy (EDS). The results were statistically analyzed. For SEM results, the BIC’s mean were significantly higher for the irradiated groups EI (977,9 μm) and EIII (1021,1 μm) compared to EII (761,5 μm) and C (807,8 μm). For BA, EIII (122573,7 μm²) showed better values for bone neoformation compared to other groups. For EDS calcium concentration there was no significantly difference between groups. The steriology analysis showed significantly higher values for BIC in EIII (1045,3 μm) compared to the other groups. For BA, EI (100068,3 μm²) and EIII (103934,5 μm²) were significantly higher. In this laser protocol, the use of LLLT induced positively perimplantar bone repair specially due to the bone implant contact improvement (20 J/cm² per session dose), as well as, better bone area neoformation within treads.

Ziel der Arbeit ist die Entwicklung von Modellen zur Entdeckung von Fehlspezifikation im Linear Logistic Test Model ( = LLTM) und verwandten Modellen der Verände\-rungs\-mes\-sung. Fehlspezifikation bedeutet hierbei, dass dem Modell ein unzutreffendes Muster latenter Traits zugrundegelegt wurde. Dies kann, vgl. z.B. [Baker,1993], zu bedeutenden Schätzfehlern führen. Die hier vorgestellten Methoden ermöglichen es unter leicht zu erfüllenden Annahmen, Aussagen über das Ausmaß der Unkorrektheit der verwendeten Modellspezifikation zu machen, ohne die in der Modellschätzung bestimmten Parameterwerte verwenden zu müssen. Zunächst wird eine auf dem Mantel-Haenszel-Test beruhende Methodik vorgestellt, die bei Tests bezüglich der Veränderungsparameter eines LLTMs als direkte Konkurrenz zu den bekannten Likelihood-Ratio-Tests für das LLTM anzusehen ist, wie sie z.B. bei [Fischer,1995a] vorgestellt werden. Weiterhin werden für das LLTM optimierte Personenfittests und daraus abgeleitete Effektgrößen vorgestellt. Diese ermöglichen das Auffinden von Subpopulationen, bei denen eine Abweichung zum angenommenen Modell aufgetreten ist. Es werden die statistischen Eigenschaften dieser Tests resp. Effektgrößen mittels Simulation und Teststärkeberechnung untersucht und Anwendungsbeispiele für diese Methoden vorgestellt.
In this thesis, new methods are developed for the detection of misspecification within Linear Logistic Test Models (=LLTM) and similar model classes for the measurement of change. The phrase "misspecification" will be used if a wrong selection of latent traits is chosen for the estimation of the LLTM. Misspecification can lead to erronious estimation [Baker,1993]). Using the newly developed methods, it is possible to measure the extent of deviations between the proposed model and the data. This can be done without using estimated parameter values. First a method is introduced which is based on the well-known Mantel-Haenszel-test. For some hypotheses, this method can be used instead of a Likelihood Ratio Test (e.g. [Fischer,1995a]). The Main topic of this thesis are uniformly most powerful tests for the measurement of person fit and related effect measures. These effect measures can be used for the identification of subpopulations where the proposed model does not hold. Statistical properties of these tests resp. effect measures are examined by simulations and power calculations using the SAS software. Furthermore, examples of the application of these methods are given.

Item response theory models (IRT) are increasingly becoming established in social science research, particularly in the analysis of performance or attitudinal data in psychology, education, medicine, marketing and other fields where testing is relevant. We propose the R package eRm (extended Rasch modeling) for computing Rasch models and several extensions. A main characteristic of some IRT models, the Rasch model being the most prominent, concerns the separation of two kinds of parameters, one that describes qualities of the subject under investigation, and the other relates to qualities of the situation under which the response of a subject is observed. Using conditional maximum likelihood (CML) estimation both types of parameters may be estimated independently from each other. IRT models are well suited to cope with dichotomous and polytomous responses, where the response categories may be unordered as well as ordered. The incorporation of linear structures allows for modeling the effects of covariates and enables the analysis of repeated categorical measurements. The eRm package fits the following models: the Rasch model, the rating scale model (RSM), and the partial credit model (PCM) as well as linear reparameterizations through covariate structures like the linear logistic test model (LLTM), the linear rating scale model (LRSM), and the linear partial credit model (LPCM). We use an unitary, efficient CML approach to estimate the item parameters and their standard errors. Graphical and numeric tools for assessing goodness-of-fit are provided. (author's abstract)
Series: Research Report Series / Department of Statistics and Mathematics

Ces travaux de thèse ont porté sur l'étude des propriétés des poudres micro et nanostructurées de Li0,3La0,57TiO3 (LLTO) vis-à-vis de l’air ambiant, en combinant les techniques suivantes : la diffraction des Rayons X, l’Analyse Thermo-Gravimétrique, la spectroscopie Infra-Rouge, et la RMN des noyaux 1H et 7Li. Les études sur le comportement du composé LLTO en milieu aqueux ont montré son instabilité vis-à-vis de l’échange ionique Li+/H+. Les ions lithium sortent de la structure perovskite pour être échangés par des protons venant de la dissociation de l’eau. La synthèse de poudre nanostructurée (méthode Pechini avec abaissement de la température de recuit) nous a permis d’observer, plus rapidement que sur les composés micrométriques synthétisés par voie solide, l’existence de ces mêmes sites de protons caractéristiques de sites de lithium échangés, prouvant la réactivité du matériau avec l’air ambiant. Les études dynamiques par mesures des temps de relaxation spin-réseau des noyaux 7Li et 1H ont également permis d’approfondir la compréhension des relations surface/volume dans les nano-matériaux. L’étude du vieillissement des poudres LLTO à l’air ambiant a démontré que l’échange ionique Li+/H+ avec la vapeur d’eau s’accompagne de la formation de carbonate de lithium, avec le dioxyde de carbone de l’air. Un traitement thermique à 400°C pendant deux heures permet de retrouver les caractéristiques du composé après synthèse, prouvant ainsi la réversibilité du processus de vieillissement. Les phases échangeables Li+/H+, dont LLTO fait parti, ont un important potentiel d’application pour le stockage du CO2
This thesis presents properties studies of nano and microstructurated powder Li0,3La0,57TiO3 (LLTO) against ambient air, using X Ray Diffraction, Thermo Gravimetric Analysis, Infra Red spectroscopy, 1H and 7Li NMR. Studies have evidenced the instability of LLTO sample toward water leading to ionic exchange Li+/H+. In aqueous solution, lithium ions come out from perovskite structure and are replaced by protons come from water dissociation. Nanostructured LLTO powder with Pechini way of synthesis allows to exhibit, quickly than for microstructurated sample, presence of such exchanged proton sites in sample after synthesis, proving its reactivity. Dynamical studies throught spin lattice relaxation time measurements of the 7Li and 1H nuclei also bring a deeper insight on the surface/volume relation in nanomaterials. Aged sample study with ambient air show that this instability toward water leads to formation of lithium carbonate with carbon dioxide from air. An thermal treatment at 400°C during 2 hours let the initial LLTO sample formation again, demonstrating the reversibility of aging process. All Li+/H+ exchangeable phases, which LLTO belongs, offer an important way of application for CO2 storage

Wie die meisten westlichen Streitkräfte, bewegt sich die Bundeswehr im Spannungsfeld zwischen hohem Personalbedarf und Fachkräftemangel. Durch ein Onlineassessment kann der Bewerbungsprozess dahingehend optimiert werden, dass fähiges Personal schneller gebunden wird. Onlineassessment hat diverse Vorteile, gleichzeitig sind damit jedoch Herausforderungen verbunden. Die wahrscheinlich größte ist es, Betrug zu minimieren, da Onlineassessment in einer weitestgehend unkontrollierten Umgebung stattfindet. Zur Entgegnung dieser Problematik dienen verschiedene Ansätze, wie beispielsweise große Itempools, wodurch einer Verbreitung der Lösung im Internet entgegengewirkt werden kann. Dieser Ansatz ist jedoch mit hohen Kosten verbunden. Automatische Itemgenerierung hingegen ermöglicht es, kostengünstig und zeiteffizient psychometrisch hochwertige Items zu erstellen. Aus diesem Grund wurden in der vorliegenden Arbeit zwei Arbeitsgedächtnistests mit automatischer Itemgenerierung für das Onlineassessment der Bundeswehr entwickelt und evaluiert, mit dem Ziel einer hohen prädiktiven Validität auf die Diagnostik vor Ort. In der ersten Studie (N = 330) wurde gezeigt, dass automatische Itemgenerierung für die entwickelten Arbeitsgedächtnistests eingesetzt werden kann. Hierbei wurden zudem zwei verschiedene zeitliche Varianten untersucht, wobei sich diejenige mit der längeren Stimulusrepräsentationszeit als vorteilhafter erwies. In der zweiten Studie (N = 621) wurden Nachweise für Reliabilität und Validität erbracht. Die Tests zeigten eine gute konvergente und diskriminante Validität. Zudem konnte einer der beiden Tests eine sehr gute prädiktive Validität aufweisen. Unter Gesamtberücksichtigung der Testgütekriterien wurde dieser Test schließlich für das Onlineassessment der Bundeswehr vorgeschlagen. Somit steht der Bundeswehr nun ein wissenschaftlich fundierter Arbeitsgedächtnistest für das Onlineassessment zur Verfügung.
Like most Western armed forces, the Bundeswehr faces both high personnel requirements and a shortage of skilled personnel. Online assessment can optimize the application process to ensure that capable personnel are retained more quickly. Online assessment has various advantages, but also challenges associated with it. Probably the biggest of these challenges is minimizing cheating, as online assessment takes place in a largely unsupervised environment. Various approaches are used to counter this problem, such as large item pools, which can be used to counter the dissemination of solutions on the Internet. However, this approach is associated with high costs. Automatic item generation, on the other hand, makes it possible to create psychometrically high-quality items in a cost-effective and time-efficient manner. For this reason, two working memory tests with automatic item generation for the German Armed Forces’ online assessment were developed and evaluated in the present study, with the aim of matching the high predictive validity of on-site diagnostics. The first study (N = 330) demonstrated that automatic item generation can be used for the developed working memory tests. Two different temporal variants were also investigated, with the longer stimulus presentation time proving to be more beneficial. The second study (N = 621) provided reliability and validity evidence. The tests showed good convergent and discriminant validity. In addition, one of the two tests demonstrated very good predictive validity. Taking into account the overall test quality criteria, this test was ultimately proposed for use in the German Armed Forces’ online assessment. Thus, the Bundeswehr now has a scientifically-grounded working memory test available for its online assessment.

L'enjeu de ce travail de thèse a été de réaliser des couches minces puis des couches épaisses non poreuses du titanate de lithium et de lanthane de formule Li3xLa2/3-xTiO3 (LLTO). Ce composé est l'un des meilleurs conducteurs ioniques solides connus actuellement. Sa conductivité, σ = 10-3 S cm-1 à 25 °C, est assurée essentiellement par les ions Li+. Pour ce faire, il a été nécessaire de choisir et de mettre au point une méthode de synthèse de chimie en solution afin de pouvoir réaliser des films sur un substrat approprié. La méthode EISA (Evaporation Induced Self-Assembly) a été utilisée, mais les films (250 nm) sont très poreux et pourraient trouver une application pour des capteurs de gaz. Pour l'application capteurs de pH ou électrode de référence, des films denses sont nécessaires. Pour les obtenir, le procédé DATEC a été employé. Les films sont réalisés à partir d'une solution composite formée des poudres céramiques dans une solution sol-gel des précurseurs. Des couches denses de LLTO de plusieurs microns ont pu être obtenues. Ces matériaux s'avèrent très intéressants en tant qu'électrode de référence totalement solide
The thesis challenge was based first on the realization of thin coatings, then of thick and no porous coatings of lithium lanthanum titanates of the series Li3xLa2/3-xTiO3 (LLTO). This oxide is a fast Li+ conductor with an ionic conductivity of σ = 10-3 S cm-1 at 25 °C. At first, a solution chemistry synthesis was chosen and developed to prepare coatings of LLTO on an appropriated wafer. The EISA (Evaporation Induced Self-Assembly) method was used, but these coatings (250 nm) are very porous and could find an application for gas sensors. For pH sensors or reference electrode applications, thick and non porous coatings are required. The DATEC process was used in this context. These films were realized with a slurry composition having ceramic powders and precursors sol-gel solution. LLTO thick coatings (10 μm) were obtained. These new materials are very interesting for an all-solid-state reference electrode

The aim of the monograph is to contribute towards bridging the gap between methodological developments that have evolved in the social sciences, in particular in psychometric research, and methods of statistical modelling in a more general framework. The first part surveys certain special psychometric models (often referred to as Rasch family of models) that share common properties: separation of parameters describing qualities of the subject under investigation and parameters related to properties of the situation under which the response of a subject is observed. Using conditional maximum likelihood estimation, both types of parameters may be estimated independently from each other. In particular, the Rasch model, the rating scale model, the partial credit model, hybrid types, and linear extensions thereof are treated. The second part reviews basic ideas of generalized linear models (GLMs) as an an excellent framework for unifying different approaches and providing a natural, technical background for model formulation, estimation and testing. This is followed by a short introduction to the software package GLIM chosen to illustrate the formulation of psychometric models in the GLM framework. The third part is the main part of this monograph and shows the application of generalized linear models to psychometric approaches. It gives a unified treatment of Rasch family models in the context of log-linear models and contains some new material on log-linear longitudinal modelling. The last part of the monograph is devoted to show the usefulness of the latent variable approach in a variety of applications, such as panel, cross-over, and therapy evaluation studies, where standard statistical analysis does not necessarily lead to satisfactory results. (author´s abstract)
Series: Research Report Series / Department of Statistics and Mathematics

Le but de ce travail de thèse, effectué dans le cadre du programme Européen IRSES « Nanolicom », était d’étudier l’influence de la nanostructuration sur les propriétés de transport de deux matériaux conducteurs par les ions lithium, la pérovskite LLTO (Li0.3La0.57TiO3) et le nasicon LATPO (Li1.3Al0.3Ti1.7(PO4)3).Une première partie importante de cette thèse a été consacrée à l’exploration et au développement de méthodes de synthèse par chimie douce plus favorables à la préparation de poudres nanométriques : la voie sol-gel, la voie des complexes polymérisables, la synthèse hydro-solvothermale et la réalisation de microémulsions. Les matériaux obtenusont ensuite été caractérisés par diffraction des rayons X, analyses thermiques et microscopies électroniques.La mise en forme des échantillons ainsi que leur densification ont également fait l’objet d’une étude approfondie. En effet, la détermination des propriétés de transport des matériaux nécessite l’utilisation de céramiques denses mais il est difficile de conserver le caractère nanostructuré des poudres lors de l’étape de frittage. Finalement, les mesures de conductivitésioniques ont été réalisées par spectroscopie d’impédance. L’ensemble des résultats obtenus a ensuite été comparé à ce qui a déjà été observé et reporté dans la littérature pour les composés microstructurés de même formulation
The aim of this thesis, which has been carried out within the European program « Nanolicom », was to study the influence of the nanostructuration on the transport properties of two lithium ionic conductors, the perovskite LLTO (Li0.3La0.57TiO3) and the nasicon LATPO (Li1.3Al0.3Ti1.7(PO4)3).The first part of this thesis is devoted to the exploration and to the optimization of the best soft chemistry route in order to get nanometric powders: sol-gel route, hydro-solvothermal synthesis, reversed microemulsion method and complex polymerizable Pechini method. The obtained materials were characterized by X-ray diffraction, thermal analysis andelectronic microscopy. Shaping and sintering of the samples were also thoroughly studied. Indeed, the determination of transport properties of the materials requires the use of dense ceramics but it is difficult to preserve the nanostructured character of the powders during the sintering step. Finally, the ionic conductivity measurements were carried out by compleximpedance spectroscopy. All results were then compared to what has been observed and reported in the literature for microstructured compounds of the same formulation

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The elderly still go through physical changes, especially musculoskeletal disorders such as sarcopenia, changes in central and peripheral nervous system, blood hypoperfusion, regenerative changes contributing to atrophy and muscle weakness, undermining the activities of daily living (AVL). The regenerative process happens about the determination, proliferation and differentiation of satellite cells through activation of muscle-specific genetic program, which is regulated by specific transcription factors, known as myogenic regulatory factors (MRFs). But in the elderly because of changes in skeletal muscle-activation of MRFs are inefficient, hindering the process of regeneration. However, recent findings showed very promising results of low laser therapy (LLT) in muscle regeneration, but the effects of this therapy when associated with aging are still unknown. This project aims to evaluate the effects of (LLT), λ = 830nm, the tibial muscle of aged rats after cryolesioning. We used 56 male Wistar rats randomly divided into 4 groups (n = 7) of young rats from 3 months to 4 groups (n = 7) of aged rats, 10 months, divided into control groups (C), groups in which the right Tibialis anterior muscle (TA) was only irradiated (I), groups in which the AT was submitted to cryolesioning (CL) and groups where the TA muscle cryolesioning and was subjected to irradiation (LI). Treatment with the laser model of the DMC, Class 3B, energy of 0.87 J, was performed every 24 h for five consecutive days, with the first application 24 hours after induction of injury. On the sixth day after injury, with the animals anesthetized and the TA muscle was carefully dissected and removed, and then the animals were euthanaziated. We carried out histological analysis of the area of the lesion with toluidine blue, and counting of blood capillaries with hematoxylin-eosin. Through analysis by RT-PCR, it was possible to analyze the expression of MyoD and VEGF genes. The results showed that there was significant increase (p <0.05) of the expression of MyoD gene, VEGF gene and capillary blood count of more prominent in elderly victims and irradiated groups than in the young. Probably the LLT increased the maturation of satellite cells into myoblasts and miotubos, enhancing the regenerative process of aged rats irradiated.
Os idosos passam por continuas mudanças físicas, principalmente músculo-esqueléticas, como sarcopenia, alterações no sistema nervoso central e periférico, hipoperfusão sanguínea, alterações regenerativas contribuindo para atrofia e fraqueza muscular, prejudicando as atividades de vida diárias (AVDs). O processo regenerativo ocorre pela determinação, proliferação, diferenciação das células satélites através da ativação do programa genético músculo-específico, que é regulado por fatores de transcrição específicos, conhecidos como fatores regulatórios miogênicos (FRMs). Porém no idoso por causa das alterações músculo-esqueléticas a ativação dos FRMs são ineficientes, prejudicando o processo de regeneração. Entretanto, recentes achados mostraram resultados muito promissores da laser terapia de baixa intensidade (LTBI) na regeneração muscular, mas os efeitos desta terapia quando associado ao envelhecimento continuam desconhecidos. Este projeto tem por objetivo avaliar os efeitos da (LTBI), λ=830nm, no músculo tibial de ratos idosos após criolesão. Foram utilizados 56 ratos machos Wistar, divididos aleatoriamente em 4 grupos (n=7) de ratos jovens de 3 meses e 4 grupos (n=7) de ratos idosos de 10 meses; subdivididos em: grupos controle (C), grupos em que o músculo tibial anterior direito (TAD) foi apenas irradiado (I), grupos em que o TAD foi submetido à criolesão (CL) e grupos onde o TAD foi submetido à criolesão e a irradiação (LI). O tratamento com o laser modelo da DMC, classe 3B, energia de 0,87 J, foi realizado a cada 24 h, durante cinco dias consecutivos, com a primeira aplicação 24 horas após a indução da lesão. No sexto dia pós lesão, com os animais vivos e anestesiados, o músculo TAD foi cuidadosamente dissecado e retirado, e logo depois os animais foram eutanaziados. Realizou-se analises histológicas da área da lesão com Azul de Toluidina e contagem dos capilares sanguíneos com Hematoxilina-eosina. Por meio da análise por RT-PCR, foi possível analisar a expressão dos genes MyoD e VEGF. Os resultados mostraram que houve aumento significativo (p<0,05) da expressão gênica da MyoD, do VEGF e da contagem de capilares sanguíneos mais proeminentes nos grupos idosos lesados e irradiados do que no grupo jovem. Provavelmente a LTBI aumentou a maturação das células satélites em mioblastos e miotubos, melhorando o processo regenerativo dos ratos idosos irradiados.

Natural killer (NK) cells are an intensively studied part of immune system, possessing unique ability to recognize and induce death of tumor and virus-infected cells without prior antigen sensitization. Their function is regulated by a fine balance of signals induced by multiple activating and inhibitory cell surface receptors and their interaction with the ligands present on the target cell. Recent research in their C-type lectin-like receptors repertoire has shown that ligands of some of these previously orphan receptors lie within their own family, describing a lectin-lectin interaction. This is the case of human inhibitory receptor NKRP1 (gene KLRB1) and its ligand LLT1 (gene CLEC2D). Previous studies have shown that overproduction of LLT1 in cancer cells or lower production of NKRP1 in NK cells is connected to cancerous manifestations. This master's thesis shows a successful production of the extracellular part of LLT1 utilizing a mammalian expression system based on transient transfection of modified human embryonic kidney (HEK) cell lines. It was found that the five cystein residues contained within the lectin domain of LLT1 tend to cause misfolding and formation of aggregates. Stabilization of the domain was achieved by restoration of the sixth cystein residue at the evolutionary conserved...

NK cells are characterized as large granular lymphocytes that play important role in innate immunity. They are called as "first line defense", because of their capability to kill the target cells very fast, in a few minutes. They recognize the target cells using their surface receptors. This diploma thesis describes the preparation of extracellular domains of the human leukocyte receptor hNKR-P1A and its physiological ligand LLT1. The proteins were produced in E. coli as inclusion bodies, refolded in vitro by rapid dilution method (hNKR-P1A) and slow dilution method (LLT1). The proteins were purificated by chromatography and characterized by mass spectrometry techniques.

Natural killer (NK) cells are an essential part of immune system, providing self-surveillance of virally infected, stress transformed or cancerous cells. NKR-P1 receptors and their ligands from clec2 gene family represent an alternate missing-self recognition system of NK cells based on interaction of highly related C-type lectin-like receptors. Human NKR-P1 has been described more than twenty years ago but still remains the sole human orthologue of this receptor family, particularly numerous in rodents. On binding to its cognate ligand LLT1, NKR-P1 can relay inhibitory or co-stimulatory signals. Although being interesting targets for their potential role in tumor immune evasion and autoimmunity, nature of their interaction is still unclear. To elucidate the architecture of their interaction, we developed a generally applicable method for recombinant expression of human NKR-P1 and LLT1 and their homologues based on transfection of HEK293S GnTI- cells. Further, we described a stabilizing mutation His176Cys, that enables for expression of highly stable and soluble LLT1. Finally, we have crystallized LLT1 and human NKR-P1 in different glycosylation states both as individuals and in complex. While both structures of LLT1 and NKR-P1 follow the classical C-type lectin-like superfamily fold, contrary to...

Signal transduction pathways play a critical role in plant growth and reproduction by perceiving extracellular signals, leading to a cellular response. FERONIA (FER) is a transmembrane receptor kinase found on the plasma membrane in the model plant Arabidopsis thaliana and plays critical roles in growth, development, and fertilization. FER works upstream of master molecular switch RAC/ROP GTPase to regulate signaling into the cytoplasm. LORELEI-Like Glycosylphosphatidylinositol (GPI)-Anchored Protein 1(LLG1) is a GPI-anchored protein and co-receptor of FER on the plasma membrane. LLG1 is responsible for chaperoning FER from the endoplasmic reticulum (ER) to its functional location on the plasma membrane. Rapid Alkalinization Factor 1 (RALF1) is a small, secreted growth-regulatory peptide that interacts with FER, regulating signaling activity. This interaction, among other, regulates the activity of a downstream plasma membrane proton ATPase (AHA2) which impacts cell growth. Additionally, published pulldown data indicates LLG1, FER, and RALF1 complex together. My data suggests that LLG1, in addition to localizing and chaperoning FER, binds directly to RALF1. My results show that this RALF1-LLG1 interaction is required for proper RALF1 mediated signaling through FER. Data also indicates that FER and LLG1 regulate RALF1 location on the plasma membrane. Additionally, RALF1 binds the MALA domain of FER. Another aspect of my thesis focuses on LURE1. LURE1 is a secreted cysteine-rich, defensin like protein which guides incoming pollen tubes to the ovule in a process called pollen tube guidance. LURE1 guides pollen tubes by binding with pollen-specific receptor kinase 6 (PRK6), located on the plasma membrane of the incoming pollen tubes, to facilitate proper fertilization. My data also shows that the ovule derived signaling molecule nitric oxide (NO), also regulated by FER, negatively impacts the property of LURE1, causing it to fall out of solution and aggregate. Furthermore, the negative impact of NO on LURE1 disrupts the binding affinity of LURE1 to PRK6. Together with data from my lab showing pollen tube arrival at the ovule triggers NO production in a FER dependent manner, my findings provide a biochemical explanation for why pollen tubes do not target fertilized ovules.