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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

Produktivita a jej meranie / Productivity and its measuring

Beno, Peter January 2009 (has links)
The aim of the methodological part of the Master's Thesis is to built up theoretical knowledge of total productivity and factor productivity and to define various approaches to productivity growth. The aim of the practical part is to analyse productivity of the company TATRASVIT SVIT - SOCKS, a.s. Consequently, the chosen indicators of the company, which are described in the theoretical part, are compared to those of the whole textile and clothing industry. A specific part is focused on the influence of the exchange rate on exporters. The specific conclusions and recommendations to the company management are drawn at the end of the Master's Thesis.
432

PrevalÃncia e fatores de risco associados à coinfecÃÃo com vÃrus da hepatite B (HBV) em pacientes HIV positivos no estado do PiauÃ. / Prevalence and risk factors associated with coinfection with hepatitis B virus (HBV) in HIV-positive patients in the state of PiauÃ.

Ana LuÃsa EulÃlio Dantas AragÃo 07 October 2011 (has links)
nÃo hà / A coinfecÃÃo entre o VÃrus da ImunodeficiÃncia Humana (HIV) e o VÃrus da Hepatite B (HBV) possui os mesmos fatores de transmissÃo e como consequÃncia os fatores de risco associados, explicam a alta prevalÃncia destes agentes infecciosos no nosso meio. O presente estudo estimou a prevalÃncia da coinfecÃÃo HIV e HBV e descreveu as caracterÃsticas individuais que agem como fatores de risco para aquisiÃÃo desta coinfecÃÃo, com o intuito de utilizar esta informaÃÃo para o aconselhamento. A amostra utilizada foi composta pelos 805 pacientes infectados com o HIV no estado do Piauà que buscaram o LACEN-PI para monitoramento da carga viral e dos linfÃcitos T CD4+. A prevalÃncia da hepatite B (HB), utilizando o marcador anti-HBc total, foi de 29,3% e, para o HBsAg este valor ficou em 2,5%. A prevalÃncia do Anti-HBc total foi 38,3% na faixa acima dos 40 anos, 38,6% para o sexo masculino, 31,9% entre os solteiros, 47,7% entre os aposentados, 50,7% entre os que relataram antecedente de icterÃcia, 54% entre os que tiveram hepatite com diagnÃstico mÃdico, 40,7% entre os com passagem por reformatÃrio ou prisÃo, 38,1% entre usuÃrios de droga nÃo endovenosa, 35,7% entre os com contato sexual com usuÃrio de droga ilÃcita, 48,8% entre os com preferÃncia homossexual/bissexual, 44,9% entre os que disseram ter contato sexual raro com prostituta, 37,1% entre os que tiveram DST e 31,4% para os com carga viral abaixo de 10.000 cÃpias/mL de sangue. Foram observadas significÃncias estatÃsticas entre as variÃveis e a frequÃncia de positividade do anti-HBc total. As informaÃÃes deste trabalho poderÃo ser utilizadas no combate, aconselhamento e prevenÃÃo do avanÃo, do nÃmero de casos HB em pacientes HIV positivos. / The coinfection between the Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) has the same transmission factors and consequently the associated risk factors explain the high prevalence of these infectious agents in our midst. This study estimated the prevalence of HIV and HBV coinfection and described the individual characteristics that act as risk factors for acquisition of coinfection, in order to use this information for advice. The sample was composed of 805 patients infected with HIV in the state of Piauà who sought the LACEN-PI for monitoring viral load and CD4 + T lymphocytes. The prevalence of Hepatitis B (HB), using the marker anti-HBc, and was 29.3% for HBsAg this value was 2.5%. The prevalence of Anti-HBc was 38.3% aged over 40 years, 38.6% for males, 31.9% among unmarried, 47.7% among retirees, 50.7% among who reported a history of jaundice, 54% among those who were diagnosed with hepatitis, 40.7% among those passing through reformatory or prison, 38.1% among non-intravenous drug users, 35.7% with sexual contact with illicit drug users, 48.8% with a preference among homosexual / bisexual, 44.9% among those who reported having sexual contact with a prostitute rare, 37.1% among those who had STD and 31.4% for those with viral load below 10,000 copies / mL of blood. We observed statistical significance between variables and the frequency of positive anti-HBc. The information in this work could be used in combat, counseling and prevention of advancement, the number of HB cases in HIV positive patients.
433

Leukocyte migration inhibition studies in pasteurellosis

Pak, Sŏng-hwan January 2011 (has links)
Photocopy of typescript. / Digitized by Kansas Correctional Industries
434

Mechanisms through which nuclear estrogen receptors remain transcriptionally active in the mouse hippocampus in absence of ovarian estrogens.

January 2017 (has links)
acase@tulane.edu / The goal of the following experiments was to determine the cellular mechanisms through which estrogen receptor activity is maintained in hippocampal cells following termination of ovarian function. Aim 1 determined that kinase signaling contributes to the maintenance of estrogen receptor activity in the hippocampus of ovariectomized mice in addition to local synthesis of brain derived “neuroestrogens”. Inhibition of both the mitogen activated protein kinase (MAPK) and phosphoinositide-3 kinase (PI3K) cascades with intracerebroventricular infusion of specific kinase inhibitors reduced estrogen response element (ERE)-dependent gene expression in the hippocampus of ovariectomized mice. Aim 2 determined that neuroestrogen synthesis, MAPK signaling, and PI3K signaling interact to regulate the transcriptional output of estrogen receptors in response to insulin like growth factor-1 receptor (IGF-1R) activation in the Neuro-2A cell culture model. Rapid IGF-1R-dependent MAPK signaling promotes, while PI3K signaling inhibits, IGF-1R-dependent activation of endogenous estrogen receptors in Neuro-2A cells. Long-term IGF-1R stimulation reduces ERE-dependent gene expression in part through phosphorylation of estrogen receptor alpha (ERα). Rapid IGF-1R-dependent activation but not long-term repression of estrogen receptor activity in Neuro-2A cells requires neuroestrogen synthesis. Aim 3 determined that exposure to 40 days of continuous unopposed estradiol at the time of ovariectomy results in lasting enhancement of estrogen receptor activity in the hippocampus and lasting enhancement of hippocampus dependent memory in female mice beyond the period of short-term estradiol exposure. Together these three aims determine that neuroestrogen synthesis and kinase signaling interact to actively maintain estrogen receptor signaling in neuronal cells and these autonomous neuronal mechanisms of estrogen receptor activation have functional consequences on cognition long after cessation of ovarian function. / 1 / Kevin J Pollard
435

The Structure of depression and anxiety symptoms in diabetic patient and community adult samples

McDade-Montez, Elizabeth Anne 01 January 2008 (has links)
Delineating and diagnosing depression and anxiety in the presence of a medical condition, such as diabetes, is complicated by the presence of overlapping symptoms that, therefore, are etiologically ambiguous. These overlapping symptoms include feelings of fatigue, concentration difficulties, restlessness, changes in appetite, irritability and autonomic arousal. The difficulty in understanding these overlapping symptoms has been proposed to lead to an underdiagnosis of depression and anxiety disorders among adults with diabetes, which is problematic given that such disorders are associated with poorer health outcomes. The goal of the current study is to test whether or not these overlapping symptoms are affected by the presence of diabetes by comparing structural models of these symptoms in adults with diabetes versus those free of major medical conditions. Participants include 226 adults with diabetes and 379 adults free of diabetes who completed a series of questionnaires assessing symptoms of depression, anxiety and health status. In addition, for adults with diabetes, the most recent hemoglobin A1c lab result was collected from patient medical records. Results indicate that overlapping symptoms were strongly related to mood for adults with and without diabetes. In conclusion, it is recommended that when these overlapping symptoms are present in adults with diabetes, depression and anxiety should be considered as possible contributors to their presence.
436

Construction of transcriptional regulatory pathways associated with hypoxia in Arabidopsis

Hsu, Fu-Chiun 01 July 2011 (has links)
Transcriptional control plays a major role in regulating hypoxic responses in plants. However, the transcriptional regulatory networks associated with hypoxia remain to be constructed. By transcriptomic analysis I show here that a novel systemic transcriptional reprogramming, which is mediated via the interplay of hormones, facilitates the survival of plants under flooding. A feasible strategy for identifying downstream targets of transcription factors (TFs) was developed. The downstream pathways of a hypoxia-responsive TF, WRKY22, were constructed. The results also show that AtERF73/HRE1 (Arabidopsis thaliana Ethylene Response Factor 73/Hypoxia Responsive ERF 1) modulate ethylene-dependent and -independent responses during hypoxia. Transcriptomic analysis of Arabidopsis in both root and shoot tissues during flooding of roots indicates the existence of a systemic communication through transcriptional reprogramming. By functional classification of affected genes, a comprehensive managing program of carbohydrate metabolism was observed. Through transcriptional profiling in ethylene and abscisic acid (ABA) signaling mutants, ein2-5 and abi4-1, an alteration of long-distance hypoxic regulation was uncovered in ein2-5 and abi4-1. Moreover, genes involved in ABA biosynthesis were also found to be differentially regulated between shoots and roots. Many members of the WRKY TF family were highly induced by hypoxia. One of the early-induced WRKYs, WRKY22, which has the highest induced level, was chosen for identifying its downstream targets. Anoxic tolerance was affected in WRKY22 overexpressing (WRKY22-OX) and knock-out (wrky22-ko) lines. Comparison of differential gene expression profiles between the wild-type and WRKY22-OX and between the wild-type and wrky22-ko lines by microarray analysis identified novel hypoxia-responsive genes as WRKY22 targets. Chromatin immunoprecipitation (ChIP) followed by microarray hybridization (ChIP-chip) and ChIP followed by quantitative PCR (ChIP-qPCR) were utilized to analyze in vivo interactions. To study the role of ethylene during hypoxia, I characterized an AP2/ERF (APETALA2/ethylene response factor) AtERF73/HRE1 that is specifically induced during hypoxia. I showed that the expression of AtERF73/HRE1 can be induced by exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene. Its hypoxic induction was reduced but not completely abolished in ethylene-insensitive mutants and in the presence of inhibitors of ethylene biosynthesis and responses. Increased ethylene sensitivity and exaggerated triple responses were observed in HRE1-RNAi knock-down lines. By comparing expression differences between the wild-type and HRE1-RNAi lines, I found that hypoxic induction of glycolytic and fermentative genes was reduced by the HRE1-RNAi knock-down mutations, whereas induction of a number of peroxidase and cytochrome P450 genes was increased. Collectively, these results show that AtERF73/HRE1 is involved in modulating ethylene responses under both normoxia and hypoxia.
437

The role of the Canonical transient receptor potential 6 (TRPC6) channel and the C terminal LIM domain protein of 36 kDa (CLP36) for platelet function / Die Rolle des Canonical transient receptor potential 6 (TRPC6) Kanals und des 36 kDa C-terminalen LIM Domänenproteins (CLP36) in der Thrombozytenfunktion

Gupta, Shuchi January 2012 (has links) (PDF)
Platelet activation and aggregation are essential to limit posttraumatic blood loss at sites of vascular injury, but also contribute to arterial thrombosis, leading to myocardial infarction and stroke. Thrombus formation is the result of well-defined molecular events, including agonist-induced elevation of intracellular calcium ([Ca2+]i) and series of cytoskeletal rearrangements. With the help of genetically modified mice, the work presented in this thesis identified novel mechanisms underlying the process of platelet activation in hemostasis and thrombosis. Store-operated calcium entry (SOCE) through Orai1 was previously shown to be the main Ca2+ influx pathway in murine platelets. The residual Ca2+ entry in the Orai1 deficient platelets suggested a role for additional non-store-operated Ca2+ (non-SOC) and receptor operated Ca2+ entry (ROCE) in maintaining platelet calcium homeostasis. Canonical transient receptor potential channel 6 (TRPC6), which is expressed in both human and murine platelets, has been attributed to be involved in SOCE as well as in diacylglycerol (DAG)-triggered ROCE. In the first part of the study, the function of TRPC6 in platelet Ca2+ signaling and activation was analyzed by using the TRPC6 knockout mice. In vitro agonist induced Ca2+ responses and in vivo platelet function were unaltered in Trpc6-/- mice. However, Trpc6-/- mice displayed a completely abolished DAG mediated Ca2+-influx but a normal SOCE. These findings identified TRPC6 as the major DAG operated ROC channel in murine platelets, but DAG mediated ROCE has no major functional relevance for hemostasis and thrombosis. In the second part of the thesis, the involvement of the PDLIM family member CLP36 in the signaling pathway of the major platelet collagen receptor glycoprotein (GP) VI was investigated. The GPVI/FcR-chain complex initiates platelet activation through a series of tyrosine phosphorylation events downstream of the FcR-chain-associated immunoreceptor tyrosine-based activation motif (ITAM). GPVI signaling has to be tightly regulated to prevent uncontrolled intravascular platelet activation, but the underlying mechanisms are not fully understood. The present study reports the adaptor protein CLP36 as a major inhibitor of GPVI-ITAM signaling in platelets. Platelets from mice expressing a truncated form of CLP36, (Clp36ΔLIM) and platelets from mice lacking the entire protein (Clp36-/-) displayed profound hyper-activation in response to GPVI-specific agonists, whereas GPCR signaling pathways remained unaffected. These alterations translated into accelerated thrombus formation and enhanced pro-coagulant activity of Clp36ΔLIM platelets and a pro-thrombotic phenotype in vivo. These studies revealed an unexpected inhibitory function of CLP36 in GPVI-ITAM signaling and established it as a key regulator of arterial thrombosis. / Die Aktivierung und die Aggregation von Thrombozyten (Blutplättchen) sind essentielle Prozesse, um Blutverluste nach Verletzungen zu begrenzen, sie spielen jedoch auch eine Rolle bei der arteriellen Thrombose, die zu Herzinfarkt und Schlaganfall führen kann. Die Thrombusbildung ist das Ergebnis wohldefinierter molekularer Vorgänge, die die Agonisten-induzierte Konzentrationserhöhung von intrazellulärem Kalzium ([Ca2+]i) und eine Reihe von Umlagerungen des Zytoskeletts mit einschließen. Die Ergebnisse dieser Arbeit, die mit Hilfe genetisch veränderter Mauslinien erzielt wurden, decken neue Mechanismen der Thrombozytenaktivierung in Thrombose und Hämostase auf. Es wurde bereits gezeigt, dass der durch Orai1 vermittelte Store-operated calcium entry (SOCE) den Haupteintrittsweg für Ca2+ in Mausthrombozyten darstellt. Der verbleibende Ca2+ Einstrom führte zur Annahme, dass zusätzlich non-store-operated Ca2+ (non-SOC) und receptor operated Ca2+ entry (ROCE) eine Rolle in der Aufrechterhaltung der Ca2+ Homöostase spielen. Dem Canonical transient receptor potential channel 6 (TRPC6), der in Thrombozyten des Menschen als auch der Maus exprimiert wird, wurde eine Rolle in dem SOCE und diacylglycerol (DAG)-vermitteltem ROCE zugeschrieben. Im ersten Teil dieser Arbeit wurde die Funktion von TRPC6 im Ca2+ Signaling und der Aktivierung von Thrombozyten mit Hilfe der TRPC6 defizienten Mauslinie untersucht. Die Funktion der Trpc6-/- Thrombozyten waren in vitro (z.B. Agonisten-induzierte Ca2+-Antworten) als auch in vivo unverändert. Jedoch zeigten Thrombozyten von Trpc6-/- Mäusen einen komplett fehlenden DAG vermittelten Kalziumeinstrom, aber normalen SOCE. Diese Ergebnisse identifizierten TRPC6 als den Haupt-DAG-aktivierten ROC Kanal in Mausthrombozyten. Jedoch hatte diese DAG vermittelte ROCE keine größere funktionelle Relevanz für Thrombose und Hämostase. Im zweiten Teil dieser Arbeit wurde die Rolle von CLP36, einem Mitglied der PDLIM Proteinfamilie, im Signalweg des Haupt-Kollagenrezeptors, Glykoprotein (GP) VI, auf Thrombozyten untersucht. Der GPVI/FcRKette Komplex initiiert die Thrombozytenaktivierung durch eine Reihe von Tyrosinphosphorylierungen, die dem FcR-Kette-assoziiertem immunoreceptor tyrosine based activation motif (ITAM) nachgeschaltet sind. GPVI-vermittelte Signale müssen sorgfältig reguliert sein, um eine unkontrollierte intravaskuläre Thrombozytenaktivierung zu verhindern. Jedoch sind die zugrunde liegenden Mechanismen nicht komplett verstanden. Die vorliegende Arbeit zeigt, dass das Adapterprotein CLP36 als ein wichtiger Inhibitor des GPVI-ITAM Signalwegs wirkt. Thrombozyten von Mäusen, welche eine trunkierte Form von CLP36 exprimieren, der die LIM-Domäne fehlt (Clp36ΔLIM), als auch von Mäusen, denen das komplette Protein fehlt (Clp36-/-), zeigten eine deutlich verstärkte Aktivierung als Antwort auf GPVI-spezifische Agonisten. Andere Signalwege aber waren nicht beeinflusst. Diese Veränderungen resultierten in einer schnelleren Thrombusbildung und erhöhten prokoagulatorischen Aktivität von Clp36ΔLIM Thrombozyten, welche sich letztendlich als prothrombotischer Phänotyp in vivo bemerkbar machten. Diese Ergebnisse deckten eine unerwartete inhibitorische Funktion von CLP36 im GPVI-ITAM Signalweg auf und etablierten CLP36 als einen wichtigen Regulator der arteriellen Thrombose.
438

Therapeutic systems for Insulin-like growth factor-1 / Therapeutische Systeme für Insulin-like growth factor-1

Schultz, Isabel January 2015 (has links) (PDF)
SUMMARY Insulin-like growth factor I (IGF-I) is a polypeptide with a molecular weight of 7.649 kDa and an anabolic potential. Thereby, IGF-I has a promising therapeutic value e.g. in muscle wasting diseases such as sarcopenia. IGF-I is mainly secreted by the liver in response to growth hormone (GH) stimulation and is rather ubiquitously found within all tissues. The effects of IGF-I are mediated by its respective IGF-I transmembrane tyrosine kinase receptor triggering the stimulation of protein synthesis, glucose uptake and the regulation of cell growth. The actions of IGF-I are modulated by six IGF binding proteins binding and transporting IGF-I in a binary or ternary complex to tissues and receptors and modulating the binding of IGF-I to its receptor. The nature of the formed complexes impacts IGF-I`s half-life, modulating the half-life between 10 minutes (free IGF-I) to 12 - 15 hours when presented in a ternary complex with IGF binding protein 3 and an acid labile subunit (ALS). Therefore, sustained drug delivery systems of free IGF-I are superficially seen as interesting for the development of controlled release profiles, as the rate of absorption is apparently and easily set slower by simple formulation as compared to the rapid rate of elimination. Thereby, one would conclude, the formulation scientist can rapidly develop systems for which the pharmacokinetics of IGF-I are dominated by the formulation release kinetics. However, the in vivo situation is more complex and as mentioned (vide supra), the half-life may easily be prolonged up to hours providing proper IGF-I complexation takes place upon systemic uptake. These and other aspects are reviewed in Chapter I, within which we introduce IGF-I as a promising therapeutic agent detailing its structure and involved receptors along with the resulting signaling pathways. We summarize the control of IGF-I pharmacokinetics in nature within the context of its complex system of 6 binding proteins to control half-life and tissue distribution. Furthermore, we describe IGF-I variants with modulated properties in vivo and originated from alternative splicing. These insights were translated into sophisticated IGF-I delivery systems for therapeutic use. Aside from safety aspects, the challenges and requirements of an effective IGF-I therapy are discussed. Localized and systemic IGF-I delivery strategies, different routes of administration as well as liquid and solid IGF-I formulations are reviewed. Effective targeting of IGF-I by protein decoration is outlined and consequently this chapter provides an interesting guidance for successful IGF-I-delivery. In Chapter II, we firstly outline the stability of IGF-I in liquid formulations with the intention to deliver the biologic through the lung and the impact of buffer type, sodium chloride concentration and pH value on IGF-I stability is presented. IGF-I integrity was preserved in histidine buffer over 4 months at room temperature, but methionine 59 oxidation (Met(o)) along with reducible dimer and trimer formation was observed in an acidic environment (pH 4.5) and using acetate buffer. Strong aggregation resulted in a complete loss of IGF-I bioactivity, whereas the potency was partly maintained in samples showing a slight aggregation and complete IGF-I oxidation. Atomization by air-jet or vibrating-mesh nebulizers yielded in limited Met(o) formation and no aggregation. The results of IGF-I nebulization experiments regarding aerosol output rate, mass median aerodynamic diameter and fine particle fraction were comparable with 0.9% sodium chloride reference, approving the applicability of liquid IGF-I formulations for pulmonary delivery. In Chapter III we escalated the development to solid delivery systems designed for alveolar landing upon inhalation and by deploying trehalose and the newly introduced for pulmonary application silk-fibroin as carriers. Microparticles were produced using nano spray drying following analyses including IGF-I integrity, IGF-I release profiles and aerodynamic properties. In vitro transport kinetics of IGF-I across pulmonary Calu-3 epithelia were suggesting similar permeability as compared to IGF-I’s cognate protein, insulin that has already been successfully administered pulmonary in clinical settings. These in vivo results were translated to an ex vivo human lung lobe model. This work showed the feasibility of pulmonary IGF-I delivery and the advantageous diversification of excipients for pulmonary formulations using silk-fibroin. Chapter IV focuses on an innovative strategy for safe and controllable IGF-I delivery. In that chapter we escalated the development to novel IGF-I analogues. The intention was to provide a versatile biologic into which galenical properties can be engineered through chemical synthesis, e.g. by site directed coupling of polymers to IGF-I. For this purpose we genetically engineered two IGF-I variants containing an unnatural amino acid at two positions, respectively, thereby integrating alkyne functions into the primary sequence of the protein. These allowed linking IGF-I with other molecules in a site specific manner, i.e. via a copper catalyzed azide-alkyne Huisgen cycloaddition (click reaction). In this chapter we mainly introduce the two IGF-I variants, detail the delivery concept and describe the optimization of the expression conditions of the IGF-I variants. In conclusion, we span from simple liquid formulations for aerolization through solid systems for tailored for maximal alveolar landing to novel engineered IGF-I analogues. Thereby, three strategies for advanced IGF-I delivery were addressed and opportunities and limitations of each were outlined. Evidence was provided that sufficiently stable and easy to manufacture formulations can be developed as typically required for first in man studies. Interestingly, solid systems – typically introduced in later stages of pharmaceutical development – were quite promising. By use of silk-fibroin as a new IGF-I carrier for pulmonary administration, a new application was established for this excipient. The demonstrated success using the ex vivo human lung lobe model provided substantial confidence that pulmonary IGF-I delivery is possible in man. Finally, this work describes the expression of two IGF-I variants containing two unnatural amino acids to implement an innovative strategy for IGF-I delivery. This genetic engineering approach was providing the fundament for novel IGF-I analogues. Ideally, the biologic is structurally modified by covalently linked moieties for the control of pharmacokinetics or for targeted delivery, e.g. into sarcopenic muscles. One future scenario is dicussed in the ‘conclusion and outlook’ section for which IGF-I is tagged to a protease sensitive linker peptide and this linker peptide in return is coupled to a polyethylenglykole (PEG) polymer (required to prolong the half-life). Some proteases may serve as proxy for sarcopenia such that protease upregulation in compromised muscle tissues drives cleavage of IGF-I from the PEG. Thereby, IGF-I is released at the seat of the disease while systemic side effects are minimized. / ZUSAMMEMFASSUNG Insulin-like growth factor I (IGF-I) ist ein 7.6 kDa großes Polypeptid, das eine anabole Wirkung besitzt und dadurch ein vielversprechendes Therapeutikum in Muskelerkrankungen wie z.B. Sarkopenie darstellt. IGF-I wird hauptsächlich von der Leber gebildet und infolge der Stimulation des Wachstumshormons Somatropin sezerniert. In fast jedem Gewebe des Körpers kommt IGF-I vor. Die Wirkungen von IGF-I werden über eigene Rezeptoren, die an die Zellmembran gebunden sind, die Rezeptor-Tyrosinkinasen, ausgeführt. Zu den Wirkungen gehören unter anderem die Stimulation der Proteinsynthese, die Aufnahme von Glucose in die Zellen und die Regulierung des Zellwachstums. Die Effekte von IGF-I werden von 6 IGF- Bindungsproteinen (IGFBP 1-6) gesteuert, indem IGF-I in einem binären oder ternären Komplex zu den Geweben transportiert oder auch die Bindung von IGF-I an den Rezeptor verhindert werden kann. Die sich bildenden Komplexe haben auch einen Einfluss auf die Halbwertszeit (HWZ) von IGF-I, da für ungebundenes IGF-I eine HWZ von ca. 10 Minuten festgestellt werden konnte, aber IGF-I, gebunden in einem ternären Komplex mit dem Bindungsprotein 3 und der säurelabilen Untereinheit (ALS) eine erhöhte HWZ von 12 – 15 Stunden aufweist. Deswegen sind „sustained drug delivery“ Systeme von ungebundenem IGF-I auf den ersten Blick interessant für die Entwicklung von kontrollierten Freisetungsprofilen, da die Absorptionsgeschwindigkeit offensichtlich und problemlos durch triviale Formulierung verlangsamt werden kann im Vergleich zu der schnellen Eliminationsgeschwindigkeit. Deshalb könnte man daraus schließen, dass ein Formulierungsexperte recht schnell Systeme entwickeln kann, in denen die Freisetzungskinetik der Formulierung über die pharmakokinetischen Eigenschaften von IGF-I dominiert. Jedoch ist die in vivo Situation wesentlich komplexer und wie oben bereits erwähnt, könnte die Halbwertszeit problemlos bis zu mehreren Stunden verlängert werden, sofern geeignete Komplexbildung von IGF-I nach systemischer Aufnahme erfolgt. Diese und weitere Aspekte werden in Kapitel I beschrieben. Außerdem stellen wir IGF-I als wertvolles Therapeutikum vor, beschreiben dessen Struktur, die beteiligten Rezeptoren und die daraus resultierenden Signalwege. Wir fassen die Kontrolle der Pharmakokinetik von IGF-I in der Natur zusammen, im Rahmen von einem komplexen System aus 6 Bindungsproteinen, die die Halbwertszeit und die Gewebeverteilung steuern. Außerdem beschreiben wir IGF-I Varianten, die veränderte Eigenschaften in vivo aufweisen und durch alternatives Spleißen entstanden sind. Diese Erkenntnisse werden in hochentwickelte „IGF-I delivery“ Systeme für den therapeutischen Gebrauch umgesetzt. Neben Sicherheitsaspekten werden die Herausforderungen und Anforderungen einer effektiven IGF-I Therapie diskutiert. Darüber hinaus wird über lokale und systemische „IGF-I delivery“ Strategien, verschiedene Verabreichungswege sowie flüssige und feste IGF-I Formulierungen berichtet. Ebenso wird die wirkungsvolle IGF-I Freisetzung am Zielort durch Ausschmückung des Proteins beschrieben und dementsprechend liefert dieses Kapitel eine interessante Orientierungshilfe für eine erfolgreiche IGF-I Therapie. Im Kapitel II untersuchen wir die Stabilität von IGF-I in flüssigen Formulierungen zur pulmonalen Anwendung bezüglich Puffersystem, Natriumchlorid Konzentration und pH Wert. Die IGF-I Integrität wurde im Histidin Puffer über 4 Monate bei Raumtemperatur aufrechterhalten. Allerdings wurde bei Verwendung eines Acetat Puffers pH 4.5, Oxidation am Methionin 59 (Met(o)) sowie die Entstehung von reduzierbaren Dimeren und Trimeren beobachtet. Starke Aggregation führte zum vollständigen Verlust der IGF-I Bioaktivität, während die Wirkung in Proben aufrechterhalten werden konnte, in denen eine geringe Aggregation, aber deutliche Oxidation festgestellt wurde. Nach der Verneblung der flüssigen IGF-I Formulierung im Histidin-Puffer pH 6.5 mit einem Druckluftvernebler und einem Schwingmembranvernebler wurde jeweils eine leichte Bildung von Met(o), aber keine Aggregatbildung ermittelt. Die Ergebnisse der IGF-I Verneblungsexperimente waren vergleichbar mit den Referenzwerten einer isotonischen Kochsalzlösung bezüglich der Abgabeleistung, dem massenbezogenen medianen aerodynamischen Durchmesser und dem Feinpartikel Anteil. Hierdurch wurde gezeigt, dass sich flüssige IGF-I Formulierungen zur pulmonalen Anwendung eignen. Im Kapitel III berichten wir von einer Weiterentwicklung zu festen IGF-I Formulierungen für die pulmonale Route unter Verwendung von Trehalose und Seidenfibroin als neues Trägermaterial für die pulmonale Applikation. Mikropartikel wurden durch Nanosprühtrocknung hergestellt und anschließend auf IGF-I Integrität, IGF-I Freisetzung und dem aerodynamischen Durchmesser untersucht. Die Kinetik des in vitro Transportes von IGF-I durch Calu-3 Lungenepithelzellen war vergleichbar zur Durchgängigkeit von Insulin, das bereits erfolgreich pulmonal verabreicht wurde. Dieser Erfolg wurden auch ex vivo in einem menschlichen Lungenlappen Model bestätigt. In der Arbeit wird somit gezeigt, dass IGF-I zur pulmonalen Anwendung geeignet ist und die Verwendung von Seidenfibroin eine nützliche Erweiterung zu den bisher eingesetzten Trägermaterialien darstellt. Das Kapitel IV konzentriert sich auf eine innovative Strategie, um IGF-I sicher und kontrollierbar zu verabreichen. In diesem Kapitel erweitern wir die Entwicklung zu neuartigen IGF-I Varianten. Wir streben damit an ein vielseitiges Biologikum zu entwickeln, dessen Eigenschaften durch chemische Reaktionen verändert werden können wie zum Beispiel die spezifische Verknüpfung mit Polymeren. Zu diesem Zweck erzeugten wir gentechnisch zwei IGF-I Varianten, die jeweils an zwei Positionen eine unnatürliche Aminosäure aufweisen und führten dadurch Alkine Gruppen in die Primärstruktur der Proteine ein. Diese Vorgehensweise ermöglicht es nun IGF-I mit anderen Molekülen positionsspezifisch zu verbinden wie zum Beispiel durch die kupferkatalysierte Azid-Alkin-Cycloaddition (Click – Reaktion). In diesem Kapitel stellen wir hauptsächlich die zwei IGF-I Varianten vor, beschreiben ausführlich das Konzept der IGF-I Zustellung und erklären die Vorgehensweise zur Optimierung der Expressionsbedingungen der IGF-I Varianten. Abschließend lässt sich sagen, dass sich diese Arbeit über einfach flüssige Formulierungen zur Verneblung, feste Formulierung mit guten aerodynamischen Eigenschaften zur Erreichung der Alveolen und neuartig entwickelte IGF-I Varianten erstreckt. Hierzu werden drei Strategien zur modernen IGF-I Gabe thematisiert und sowohl die Möglichkeiten als auch die Grenzen der jeweiligen Therapie erörtert. Wir haben den Nachweis erbracht, dass ausreichend stabile und leicht herzustellende Formulierungen entwickelt werden können, die üblicherweise für „First-In-Man“ Studien benötigt werden. Interessanterweise stellten sich die festen Formulierungen, die eigentlich in den späteren Phasen der pharmazeutischen Entwicklung eingeführt werden, als sehr vielversprechend heraus. Durch den Einsatz von Seidenfibroin als neuen Träger zur pulmonalen Anwendung haben wir einen neuen Verwendungszweck für Seidenfibroin etabliert. Der erfolgreiche Versuch ex vivo am menschlichen Lungenlappen Model liefert die feste Überzeugung, dass es möglich ist, IGF-I im Menschen pulmonal anzuwenden. Letztendlich, beschreibt die Arbeit die Expression von zwei IGF-I Varianten, die zwei unnatürliche Aminosäuren aufweisen, um eine neuartige Strategie zur IGF-I Verabreichung umzusetzen. Dieser gentechnische Ansatz liefert die Grundlage für neue IGF-I Varianten. Idealerweise, wird das Biopharmazeutikum strukturell durch kovalent gebundene Reste verändert, um die pharmakokinetischen Eigenschaften zu steuern oder um zielgenaue Wirkstoffabgabe zu erreichen zum Beispiel in den sarkopenischen Muskeln. Ein Zukunftsszenarium wird im Abschnitt „Conclusion and Outlook“ diskutiert, in dem IGF-I mit einem Protease empfindlichen Linker versehen wird, der wiederum mit einem Polyethylenglykol (PEG) Polymer verknüpft ist. Der PEG Rest wird benötigt, um die Hablbwertszeit von IGF-I zu erhöhen. Einige Proteasen könnten als Stellvertreter für Sarkopenie dienen, so dass die Hochregulierung der Proteasen in gefährdeten Muskelgeweben zur Spaltung von IGF-I und dem PEG Rest führt. Dadurch wird IGF-I am Ursprung der Erkrankungen freigesetzt, während die systemischen Nebenwirkungen weitgehend vermindert sind.
439

Studies of bladder cancer progression

Hung, Tzong Tyng, Clinical School - Prince of Wales Hospital, Faculty of Medicine, UNSW January 2009 (has links)
Bladder cancer (BlCa) is the second most common genitourinary cancer, affecting both men and women. Most (70%) cases present at the superficial stage; 20% of these recur with muscle-invasive disease. Major genetic alterations associated with BlCa include: loss/gain in expression or mutations in Retinoblastoma (RB) gene, human epidermal growth factor receptors (HERs), H-ras, p53 and FGFR3. Only p53 mutations are well correlated with invasive BlCa; other changes show variable correlations with disease status. To understand the progression of BlCa, a model of nine human BlCa cell sublines derived from a single parent but differing in in vivo characteristics, has been developed previously. These cells represent a heterogenous population from a single tumour and a model of different stages of BlCa progression, from non-tumourigenic to invasive. Two sublines were selected for further investigation: C3 (non-tumourigenic) and B8 (invasive). These were transfected with green (C3-GSP-2) and red fluorescent reporters (B8-RSP-gck) respectively to investigate the effects of their co-injection in vivo, specifically, promotion of C3 tumour growth by B8 cells. Surprisingly, B8 tumour growth was inhibited by C3 cells in vivo at different cell numbers and proportions of cells injected. Microarray analysis of C3 and B8 cells revealed differential expression of 1367 genes with dramatic differences in the transforming growth factor-?? and integrin-mediated pathways. Gene expression of BMP2, INHBB, FST, NOG, ID4 and TGF- ??1, in the TGF- ?? pathway was further analysed with qRT-PCR in all nine sublines. Expression of BMP2 was significantly related to tumourigenic potential (p=0.0238, Mann-Whitney) and INHBB to invasive ability (p=0.0476, Mann-Whitney). The BlCa model did not include a metastatic component. To broaden the model, cell lines were established from an invaded lymph-node (B8-RSP-LN) and a bone-metastasis (B8-RSP-BN) after subcutaneous and intra-cardiac injection of B8-RSP-gck cells. No significant differences were observed in the migratory capability and anchorage-independent colony formation of these metastatic cells compared with B8 cells. Evaluation of expression of the panel of TGF-beta genes (BMP2, INHBB, FST, NOG, ID4 and TGF- ??1) and metastasis-related genes (MMP9, MMP2 and KAI1) indicated that expression of BMP2, FST, ID4 and MMP9 was decreased or lost in the metastatic sublines.
440

Mechanisms of intracellular and extracellular cytokine production from the human leukaemia inhibitory factor gene

Voyle, Roger Bruce. January 1999 (has links) (PDF)
Addendum attached to back facing leaves. Includes bibliographical references (leaves 172-199). The findings establish leukemia inhibitory factor, and possibly oncostatin M, as new members of a small but growing class of cytokines produced in an intracellularly active form and also suggest that the production of alternate transcripts and intercellularly-retained proteins may be a common and important feature of cytokines of the IL-6 and other families.

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