Stickoxid (NO) moduliert die Regulation des Plättchenwachstumsfaktorrezeptors α(PDGFR-α) in renalen Mesangiumzellen (MZ) der Ratte

NO, a diffusible gas with various physiological and pathological properties, is synthesized by three different forms of nitric oxide synthases (NOS). The effects of NO depend particularly on the actual NO concentration. At low concentrations, NO participates in many physiological processes, whereas high concentrations of NO, produced e.g. by the inducible NOS in the course of inflammatory diseases, initiate apoptosis and necrosis. PDGF, a potent growth factor, is able to counteract NO-production by inhibition of iNOS expression and activity. This work analyses the reciprocal control mechanisms of NO on the PDGF signalling system in rat glomerular mesangial cells (MC). In the first part of my work, the effect of NO on the expression of the PDGF ligands and their receptors was analysed. MC were stimulated with the NO delivering agent DETA-NO. PDGFR mRNA levels were analysed in polymerase chain reaction (PCR) for both receptor subunits. PDGFR-α mRNA expression was time- and dose-dependently induced by NO, whereas mRNA expression of the β-subunit was not significantly affected by DETA-NO. The time- and dose-dependent induction of PDGFR-α mRNA expression by NO could also be confirmed on the protein level by Western blotting. In the second part, the influence of endogenously produced NO on PDGFR-α -protein expression was investigated. MC were stimulated with the cytokine IL-1β, which is a known inducer of iNOS expression in rat MC. Consequently, IL-1β induces PDGFR-α expression. To discriminate between the IL-1β-iNOS-NO pathway and direct IL-1β mediated promoter activation, cells were costimulated with the NOS inhibitor L-NMMA. L-NMMA was not able to completely reverse the IL-1β mediated induction of PDGFR-α protein expression, but it diminished the effect significantly down to 60 %. This result reveals, that IL-1β involves iNOS activation to a certain degree for PDGFR-α induction. There are multiple mechanisms described for NO induced signalling. At subtoxic concentrations the most common pathway is mediated via activation of the soluble guanylyl cyclase (sGC). To examine whether NO uses the sGC pathway to induce PDGFR-α expression, DETA-NO stimulated MC were cotreated with the sGC inhibitor ODQ. ODQ reversed almost completely the NO-mediated effect. Additionally, MC were incubated with the sGC activator YC-1. YC-1 was able to mimic PDGFR-α protein induction concentrationV dependently. Taken together both experiments indicate that the NO induced stimulation of PDGFR-α expression is due to sGC activation. Since NO affects many genes also on a transcriptional level, PDGFR-α promoter was cloned and promoter analysis was performed by the dual-luciferase reporter assay system. MC, transfected with a PDGFRα promoter/luciferase construct were stimulated with DETA-NO or with 8-Bromo-cAMP, a known inducer of PDGFR-α transcription. 8-Bromo-cAMP but not DETA-NO was able to induce PDGFR-α promoter transcription, indicating that the NOdependent stimulation of PDGFR-α expression is mediated posttranscriptionally or, alternatively, that the putative NO responsive element in the PDGFR-α promoter is not included in the cloned genomic DNA fragment. In the last part of my work, the functionality of NO on PDGFR-α expression was tested by analysis of the phosphorylation state of the α-receptor and of the downstream effector molecule protein kinase B (PKB). MC were prestimulated with DETA-NO and thereafter incubated for 15 min with PDGF-BB to activate the receptor. Western blot analysis, performed with anti-pTyr720-PDGFR-α-specific antibody, revealed that the NO-induced elevation of basal PDGFR-α protein level also increases PDGFR-α phosphorylation. Furthermore, an enhanced phosphorylation level of PKB was detected in DETA-NO pretreated cells, which were co-incubated with PDGF-AA, a PDGF isoform that selectively activates the PDGFR-α subunit. In co-operation with Dr. L. Schäfer (University of Münster), the NO-modulated induction of PDGFR-α expression was confirmed in an in vivo model of anti-Thy.1.1 nephritis. Inhibition of iNOS by the iNOS-specific inhibitor L-N6-(1-iminoethyl)lysine (L-NIL) reduced PDGFR- α expression as shown by immunohistochemistry and Western blot analysis. In conclusion, I have demonstrated that exogenously applied or endogenously produced NO induces the expression of PDGFR-α protein and that this increase permits enhanced phosphorylation of downstream effector molecules, which indicates that the actual amount of the receptor dictates the strength of the mitogenic effects of PDGF. NO induces the expression of PDGFR-α in vitro and in vivo. The pathophysiological significance of the NOmediated upregulation of PDGFR-α expression has yet to be clarified in further in vivo experiments.NO ist ein gasförmiges Molekül, das durch drei verschiedene NO-Synthasen hergestellt werden kann. Die Signalkaskaden von NO sind multipel und sehr stark von der jeweiligen Konzentration abhängig. In niedrigen Dosen ist NO an der Regulation physiologischer Prozesse beteiligt, wohingegen hohe NO-Spiegel, wie sie von der induzierbaren NO Synthase (iNOS) im Verlauf von entzündlichen Erkrankungen produziert werden, zytotoxische Effekte wie Apoptose und Nekrose bedingen können. Der Wachstumsfaktor PDGF kann durch Inhibition der iNOS Expression, dieser hohen NO Produktion entgegen wirken. Ob NO im Gegenzug auch eine Wirkung auf das PDGF-System aufweist, sollte mit dieser Arbeit geklärt werden. Da die Aktivität von PDGF letztendlich von der Rezeptormenge abhängt, wurde die expressionsmodulatorische Wirkung von NO auf der PDGF-Rezeptorebene untersucht. Im ersten Teil der Arbeit wurden MZ mit dem NO-Donator DETA-NO stimuliert. Mittels PCR-Analyse konnte gezeigt werden, dass NO die PDGFR-α-mRNA Expression zeit- und dosisabhängig induziert. Die Expression von PDGFR-β wird hingegen nicht wesentlich beeinflusst. Western-Blot-Analysen (WB) bestätigten die Regulierbarkeit des PDGFR-α auch auf Translationsebene. Als nächstes sollte geprüft werden, ob die durch exogene Applikation eines NO-Donatoren hervorgerufene Induktion des PDGFR-α auch durch eine endogene NO-Produktion imitiert werden kann. Hierzu wurden MZ mit dem Zytokin IL-1β inkubiert. IL-1β steigert die iNOS und auch die PDGFR-α-Expression durch Induktion von Transkriptionsfaktoren. Die IL-1β bedingte PDGFR-α-Expression könnte dabei über zwei Mechanismen reguliert werden: Einerseits über die gesteigerte Synthese von NO durch iNOS und andererseits durch direkte Interaktionen der IL-1β-induzierten Transkriptionsfaktoren mit dem PDGFR-α-Promotor. Um die NO bzw. iNOS-vermittelte von der Promotor-vermittelten Wirkung zu unterscheiden, wurden MZ zusätzlich mit dem NOS-Inhibitor L-NMMA inkubiert. L-NMMA war im Stande die durch IL-1β hervorgerufene Erhöhung der PDGFR-α Proteinmenge signifikant auf 60% zu reduzieren, was die Beteiligung der iNOS bzw. von NO an der IL-1β vermittelten Regulation des PDGFR-α impliziert. NO entfaltet seine Wirkung über verschiedene Signalkaskaden. Der klassische Weg verläuft über die Aktivierung der löslichen Guanylatzyklase (sGC). Um die Beteiligung der sGC an der NO-vermittelten Induktion des PDGFR-α zu untersuchen, wurden DETA-NO stimulierte MZ zeitgleich mit ODQ, einem Inhibitor der sGC inkubiert. Die durch NO verursachte Erhöhung der PDGFR-α-Proteinmenge konnte durch die gleichzeitige Zugabe von ODQ komplett gehemmt werden. Die Behandlung von MC mit dem sGC-Aktivator YC-1 imitierte andererseits den NO-Effekt. Beide Versuche zusammengenommen beweisen die Notwendigkeit der sGC-Aktivierung zur NO-vermittelten Induktion des PDGFR-α. Da viele Gene schon auf Transkriptionsebene durch NO beeinflusst werden, wurde der an einen Vektor gebundene PDGFR-α-Promotor vor das Luziferase-Gen kloniert und MZ mit diesem Konstrukt transfiziert. Die transfizierten MZ wurden mit DETA-NO oder 8-BromocAMP stimuliert. cAMP erhöht die Aktivität des PDGFR-α-Promotors und diente somit als Positivkontrolle. Die Promotoraktivität wurde indirekt über das Luziferase-Renilla-System bestimmt. Da NO im Gegensatz zu 8-Bromo-cAMP die Promotoraktivität nicht erhöhte, ist davon auszugehen, dass die NO-abhängige Induktion des PDGFR-α posttranskriptionell erfolgt oder, dass das NO-responsive Element nicht in unserem Konstrukt enthalten war. Im letzten Abschnitt meiner Arbeit wurde die Funktionsfähigkeit des neusynthetisierten PDGFR-α Proteins bestätigt. Hierzu wurde die Phosphorylisierung vom PDGFR-α und von einem weiteren in der PDGF-Signalkaskade angeordneten Enzym, der antiapoptotisch wirksamen Proteinkinase B (PKB) untersucht. Mit DETA-NO vorbehandelte MZ wurden mit PDGF-BB stimuliert und eine Nachweisanalyse mit einem Phospho-spezifischen Antikörper der gegen pTyr720-PDGFR-α (pPDGFR-α) gerichtet ist, durchgeführt. Der Vergleich mit nichtvorbehandelten MZ belegt eindeutig, dass die NO vermittelte Erhöhung der basalen PDGFR-α-Proteinmenge auch zu einer Zunahme an detektierbarem pPDGFR-α führt, die dann wiederum eine Verstärkung der Signaltransduktion zur Folge hat. So konnten in DETANO vorbehandelten MZ, die mit dem α-Rezeptor spezifischen Liganden PDGF-AA stimuliert wurden, eine vergleichsweise erhöhte PKB-Phosphorylierung festgestellt werden. In einer Kooperation mit Dr. L. Schäfer (Universität Münster) konnte ferner gezeigt werden, dass die NO-Abhängigkeit der PDGFR-α Proteinexpression auch im Krankheitsverlauf eines experimentellen Glomerulonephritismodells, zu beobachten ist. Durch WB-Analysen und immunhistologischen Färbungen konnte dargelegt werden, dass die Vorinjektion des iNO-Sspezifischen Inhibitors L-NIL die Produktion von phosphoryliertem und unphosphoryliertem PDGFR-α Protein in Anti-Thy.1.1-behandelten Ratten signifikant hemmt. Zusammenfassend weisen die Ergebnisse darauf hin, dass NO über eine Aktivierung der sGC, die Produktion von funktionsfähigem PDGFR-α- Protein in vitro und in vivo steigert. Die pathophysiologische Bedeutung der NO-vermittelten Induktion des PDGFR-α im Krankheitsprozess der GN, wird gegenwärtig in weiteren in vivo Experimenten untersucht

Por Que Dizem “Adiós”: Uma Compreensão Crítica Da Economia Política Da Migração Contemporânea De Venezuelanos

The aim of this study is to create a pattern by looking at the historical background of the migration movement in Venezuela and to reveal that the Venezuelan diaspora is a social movement that takes place with push factors, based on the push and pull theory. In this context, it has been focused on the economic and political background of the Venezuelan migration movement, and by looking at the political economy history, it has been determined that the migration movement took place in three different waves. By analyzing the push factors, the development of the migration phenomenon in Venezuela was followed and a framework was drawn with the sociological contexts of the target countries. The main argument of the article is the claim that the current Venezuelan migration movement took place with push factors, considering the economic and political conditions, while the first two migration waves were depending on the pull factors.El objetivo de este estudio es crear un patrón al observar los antecedentes históricos del movimiento migratorio en Venezuela y revelar que la diáspora venezolana es un movimiento social que se lleva a cabo con factores de empuje, basados ​​en la teoría de empujar y tirar. En este contexto, se ha centrado en los antecedentes económicos y políticos del movimiento migratorio venezolano y, al observar la historia de la economía política, se ha determinado que el movimiento migratorio se dio en tres oleadas diferentes. Mediante el análisis de los factores de empuje, se siguió el desarrollo del fenómeno migratorio en Venezuela y se trazó un marco con los contextos sociológicos de los países objetivo. El argumento principal del artículo es la afirmación de que el movimiento migratorio venezolano actual se dio con factores de empuje, considerando las condiciones económicas y políticas, mientras que las dos primeras olas migratorias dependieron de los factores de atracción.O objetivo deste estudo é criar um padrão olhando para o contexto histórico do movimento migratório na Venezuela e revelar que a diáspora venezuelana é um movimento social que ocorre com fatores push, com base na teoria push and pull. Nesse contexto, concentrou-se no contexto econômico e político do movimento migratório venezuelano e, analisando a história da economia política, determinou-se que o movimento migratório ocorreu em três ondas diferentes. Ao analisar os fatores de impulso, acompanhou-se o desenvolvimento do fenômeno migratório na Venezuela e traçou-se um quadro com os contextos sociológicos dos países-alvo. O principal argumento do artigo é a afirmação de que o atual movimento migratório venezuelano ocorreu com fatores de impulso, considerando as condições econômicas e políticas, enquanto as duas primeiras ondas migratórias foram dependentes dos fatores de atração

Comparison Of Design Rules With Dynamic Modeling Of A Full Scale Wastewater Treatment Plant: Paşaköy Biological Nutrient Removal Facility

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2011Dünyadaki su kaynaklarının zamanla kirlenmesi, atıksu desarj limitlerinin arttırılması ve atıksulardan nutrient (azot, fosfor) gideriminin gerekliliğini de beraberinde getirmiştir. Diğer nütrient giderimi alternatiflerinin yanında aktif çamur teknolojisi ekonomik olması sebebiyle dünyada yaygın olarak kullanılmaktadır. Öngörülen desarj limitlerinin sağlanması da bu aktif çamur sistemlerinin şartlara uygun tasarımı, işletilmesi ve/veya optimizasyonu ile yerine getirilmektedir. Aktif çamur modelleri artık aktif çamur sistemlerinin tasarımı, kontrolü ve optimizasyon çalışmalarında yaygın olarak kullanılmaktadır. Ancak, bu modellerin doğru ve verimli olarak kullanılabilmesi için (1) kesin model bazlı-atıksu karakterizayonu (2) arıtma tesislerine uygun modelleme yaklaşımı ve metodolojisinin uygulanması ve bunların sonucu olarak (3) elde edilen model sonuçlarının doğru olarak yorumlanması gerekmektedir. Çalışmanın ilk aşamasında, işletme şartlarında atıksu karakterizasyonu belirlendi ve dizayn için persentil değerleri hesaplandı. Sonra, tesis farklı dizayn metodlarına göre (ATV-DVWK 131-E, Cape Town Üniversitesi ve Su Ortamında Araştırma Kuruluşu) tasarlanarak bunların sonuçları karşılaştırılmıştır. Çalışmanın ikinci aşamasında, tam ölçekli tesis, simülasyon programı yardımıyla kararlı hal ve dinamik koşullarda modellendi ve model sonuçları desarj konsantrasyonlarıyla karşılaştırıldı. Çalışmanın son aşamasında, uzun havalandırma tipi tam ölçekli aktik çamur tesisinin nütrient giderimi performansı modelleme çalışması ile incelenmiştir.Increasing pollution of water sources in world brings along strict discharge standarts together with necessity of efficient nutrient (nitrogen and phosphorus) removal from wastewaters. Compared to other treatment alternatives, the activated sludge technology is more convenient in terms of investment and operational costs. The discharge standarts imposed should only be secured by appropiate design, operation and refrofit of activated sludge plants. Activated sludge models have been widely used for the design, control and optimization of activated sludge plants operated for organic carbon and nutrient removal. Hovewer, appropiate use of those models essentially requires (1) precise influent-wastewater characterization (2) wise use of calibration methodology for activated sludge models and as a result: (3) interpretation of results obtained from modeling study. In the first part of the study, the wastewater characterization was determined at the operating conditions and the percentil values were calculated for the design. Then, the plant was designed with different (ATV-DVWK 131-E, University Cape Town and Water Environment Research Foundation) design methods and the results were compared. In the second part of the study, the nutrient removal mechanism was evaluated for the plant was modelled in steady-state and dynamic conditions using plant-wide simulation model programme and the model results were compared with the discharge concentrations. Last part of the study deals with the investigation of nutrient removal performance of extended aeration type full-scale activated sludge plant.Yüksek LisansM.Sc

Trakya Bölgesindeki bal arılarında (apis mellifera l. ) mtDNA 16S rDNA ve ND5 genleri analizi

Bu çalışmada, Türkiye’nin Trakya bölgesinde bulunan bal arısı populasyonları arasındaki genetik varyasyon 16S rDNA ve ND5 bölgeleri kullanılarak araştırılmıştır. PCR-RFLP ve DNA dizi analizi yöntemlerinden yararlanılarak mitokondriyel genomda DraI, MboII ve SwaI restriksiyon enzimleri kullanılarak değerlendirilmesi amaçlanmıştır. Trakya bölgesini temsil edebilecek bal arısı populasyonlarından örneklenen Tekirdağ, Gökçeada, Çanakkale, Edirne ve Kırklareli’nin farklı yörelerinden olmak üzere toplam 100 adet işçi arı örneği materyal olarak kullanılmıştır. Bu çalışmada, 16S rDNA ve ND5 gen bölgelerinin DraI ve SwaI restriksiyon enzimleri ile kesiminde iki farklı haplotip belirlenmiştir. 16S rDNA/DraI kesimi bakımından Tip 1 haplotipinde 315, 212, 116, 116, 92, 70 ve 44 bç'lik yedi farklı bant gözlenmiştir. Tip 2 haplotipinde, C ? T transizyonu sonucu 705. pozisyonda meydana gelen nokta mutasyonu sonucu bu haplotip 8 bant görüntüsünü vermiştir (215, 212, 116, 116, 100, 92, 70 ve 44 bç). 16S rDNA/SwaI bakımından Tip 1 haplotipinde 359, 324 ve 282 bç’lik 3 farklı banttan oluşan kesim profili belirlenmiştir. 16S rDNA gen bölgesinin 196. nükleotidinde (A?T transversiyonu) meydana gelen nokta mutasyonu sonucu SwaI enziminin yeni bir kesim noktası oluşmuş ve 359, 324, 195 ve 87 bç’lik 4 bant profili elde edilmiştir. Fakat bu bölgenin MboII restriksiyon enzimi kesimi sonucunda tüm örneklerde 16S rDNA/MboII bakımından tek tip haplotip belirlenmiştir. ND5 bölgesinde ise DraI restriksiyon enzimi kesimi sonucunda varyasyon belirlenmiş ve iki haplotip elde edilmiştir. ND5/DraI bakımından Tip 1 haplotipinde 440, 270 ve 112 bç’lik 3 farklı banttan oluşan kesim profili tespit edilmiştir. ND5 gen bölgesinin 383. pozisyonda (T?C transizyonu) tek nükleotid değişimi sonucu DraI restriksiyon enziminin kesim noktası kaybolmuştur. Böylece jelde 112, 270 ve 440 bç’lik 3 bant sayısı 440 bç’lik bantın kaybolması sonucu 552 ve 270 bç’lik 2 bant modeli oluşan kesim profili elde edilmiştir. ND5 bölgesinin MboII ve SwaI restriksiyon enzimleri ile kesiminde varyasyon bulunmamış ve tüm örneklerde tek tip haplotip elde edilmiştir

Efficient and secure delivery of area-persistent safety messages in vehicular ad hoc networks

In this thesis, we propose an adaptive mechanism for the delivery of safety messages in vehicular networks in an authenticated and privacy-preserving manner. The traditional approach to message delivery for driving safety applications running on vehicular ad hoc networks (VANETs) has been to increase redundancy, often at the sake of other applications running on the network. We argue that this approach does not accommodate the traffic conditions of crowded cities like İstanbul, and present a probabilistic method for the dissemination of area-persistent safety messages in infrastructureless vehicular networks that dynamically adapts itself to changing road conditions. Our proposed protocol utilizes short group signatures for privacy-preserving authentication, and keyed-Hash Message Authentication Codes (HMACs) with one-way hash chains to decrease computational load on Onboard Units (OBUs). We also introduce a vehicular mobility model that creates scenarios of high-speed traffic on crowded highways based on realistic assumptions, and measure the performance of the proposed protocol using scenarios generated by this model. Our simulations show that the proposed method decreases network traffic by up to 82% and shortens delivery delays by up to 13% when compared to non-probabilistic methods in highway scenarios with medium to high vehicle density

Disiplinler Arası Modelleme Problemi Yoluyla Kavram Öğretimi: Enerji Tasarrufu Problemi

Bu çalışmanın temel amacı öğrencilerin model geliştirme süreçlerini ve bir disiplinler arası modelleme problemi ile bazı fen ve matematik terimlerini öğrenmelerin görmektir. Bu amaçla, araştırmacılar Fen öğretmeni ile birlikte çalışarak disiplinler arası bir modelleme problemi olan "Enerji Tasarrufu Problemi" geliştirdiler. Geliştirilen bu problem, Türkiye'nin Doğu Anadolu Bölgesinde bir il merkezinde bulunan bir okulda 3-4 kişilik gruplar halinde 7. sınıf öğrencilerine uygulanmıştır.  Disiplinler arası problem çözme sürecinde, öğrenciler fenle ilgili bazı kavramları öğrendiler ve bu kavramları birbirleriyle ilişkilendirdikten sonra gelecekteki modellerinde hangi faktörleri dahil edeceklerini ve nasıl ölçeceklerini tartıştılar. Öğrencilerin modellerinin birbirlerinden farklı olmasında öğrencilerin ilk defa böyle bir problemle karşılaşmış olmaları, gruplar içindeki farklı düşünme biçimleri ve modelleme problemlerinin doğası gereği karmaşık olması etkili olmuştur

Investigation of the Relationship between Study Approaches and Self-regulated Learning Skills of Teacher Candidates

AbstractThis study aims the investigating the relationship between study process and their self-regulated learning skills of teacher candidates. This research is designed as relational scanning model. In the study, 2 scales are used as tool of data collection: Self-regulating Learning skills (SRLS) Scale, developed by Turan (2009), Study Process Questionnaire (SPQ) revised by Biggs, Kember & Leung (2001), adapted in Turkish by Yılmaz & Orhan (2011a). 272 Teacher candidates from Turkish, Science, social studies, elementary school, mathematics, psychological counseling-guidance education forms the sample of the study. In order to analyze the data, SPSS 16.00, ANOVA, independent t-test, Pearson correlation coefficient techniques are used. At the end of the study, between SRLS scale with profound approach factor of SPQ has a positive relation and with superficial approach factor of SPQ has a negative relation. The significant differences weren’t found between the graduated secondary schools with scales; but according to gender and to the department, significant differences were found between SRLS scale with superficial approach factor of SPQ

Maksillofasiyal travma geçirmiş bir hastaya multidisipliner tedavi yaklaşımı: Olgu sunumu

Maksillofasiyal travma geçirmiş hastaların tedavisi başarı sağlamakta en çok zorlanılan vakaların başında gelmekte ve genellikle multidisipliner yaklaşım ile vakaya özel bir planlama gerektirmektedir. Bu olgu sunumunun amacı geçirdiği maksillofasiyal travma nedeniyle sert ve yumuşak doku kaybı şikayeti olan bir hastanın implant destekli sabit parsiyel protezler ile gerçekleştirilen multidisipliner tedavisini sunmaktır. 47 yaşında erkek hasta geçirdiği maksillofasiyal travma nedeniyle diş, kemik ve yumuşak doku kaybı şikayeti ile kliniğimize başvurdu. Mandibular sol bölgede daha önce cerrahi plaklarla stabilize edilmiş bir fraktür gözlendi. İyileşme sonrasında her bir çeneye beşer adet dental implant yerleştirildi. Kişisel abutmentlar ile entegre olan tek parça metal altyapılar üretildi ve okluzyon kontrolü sonrasında metal-seramik ve metalkompozit rezin restorasyonlar hastaya teslim edildi. Hastanın estetik ve fonksiyonel beklentileri tedavi sonrasında başarılı bir şekilde karşılandı. 1 yıllık takip sonucunda herhangi bir estetik, biyolojik, fonksiyonel ya da biyomekanik komplikasyon gözlenmedi