• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 15
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

X-ray crystallographic studies of bovine serum albumin and helicobacter pylori thioredoxin-2

Tai, HengChiat 20 January 2005
The initial motivation for crystallization of Bovine Serum Albumin (BSA) is an interest to understand how thiomolybdates interact with BSA and suppress copper intake from the food sources of cattle. The main objective of my research work is to determine the crystal structure of BSA using X-ray crystallography techniques. Once the tertiary structure of BSA is determined, its structural information can help us to study the interactions between BSA, copper, and thiomolybdates, and to understand the way in which thiomolybdates render copper unavailable in cattle. Many trials for the optimal crystallization conditions of BSA were attempted in order to grow high-quality BSA crystals. However, all crystals only diffract to 8 Å resolution limit. Such resolution is not sufficient to solve the tertiary structure of BSA. Another objective of my research was to crystallize Thioredoxin-2 (Trx-2) to obtain larger crystals which may lead to high resolution crystallographic data, better than 2.4 Å, for protein structure refinement. This is because Trx-2 diffraction data that had been collected are split at high resolution. The ambiguous data at high resolution might impede the structure refinement and even can cause the three-dimensional structure of Trx-2 to not be refined successfully. A number of attempts were conducted for crystallizing Trx-2 to grow bigger and higher quality of Trx-2 crystals. However, the improvement of crystal dimensions was not significant, the diffraction resolution limits are similar to previous published data, and the split data at high resolution was still observed.
2

X-ray crystallographic studies of bovine serum albumin and helicobacter pylori thioredoxin-2

Tai, HengChiat 20 January 2005 (has links)
The initial motivation for crystallization of Bovine Serum Albumin (BSA) is an interest to understand how thiomolybdates interact with BSA and suppress copper intake from the food sources of cattle. The main objective of my research work is to determine the crystal structure of BSA using X-ray crystallography techniques. Once the tertiary structure of BSA is determined, its structural information can help us to study the interactions between BSA, copper, and thiomolybdates, and to understand the way in which thiomolybdates render copper unavailable in cattle. Many trials for the optimal crystallization conditions of BSA were attempted in order to grow high-quality BSA crystals. However, all crystals only diffract to 8 Å resolution limit. Such resolution is not sufficient to solve the tertiary structure of BSA. Another objective of my research was to crystallize Thioredoxin-2 (Trx-2) to obtain larger crystals which may lead to high resolution crystallographic data, better than 2.4 Å, for protein structure refinement. This is because Trx-2 diffraction data that had been collected are split at high resolution. The ambiguous data at high resolution might impede the structure refinement and even can cause the three-dimensional structure of Trx-2 to not be refined successfully. A number of attempts were conducted for crystallizing Trx-2 to grow bigger and higher quality of Trx-2 crystals. However, the improvement of crystal dimensions was not significant, the diffraction resolution limits are similar to previous published data, and the split data at high resolution was still observed.
3

The Regulation of Growth Factor Receptors EGFR and IGF-IR and the Growth Factor VEGF by Thioredoxin-1

Bair III, Warner B January 2005 (has links)
Thioredoxin-1 (Trx-1) is a redox protein that is overexpressed in many tumors where it is associated with tumor growth, inhibited apoptosis and decreased patient survival. Through redox reactions, Trx-1 is able to reduce a number of proteins including transcription factors. Sp1 activation has been implicated in the regulation of many genes involved in cellular growth and survival and its overexpression in certain cancer correlates with decreased patient survival. We demonstrate that Trx-1 is able to activate Sp1 in a redox dependent manner. Trx-1 overexpression increases Sp1 transactivation and DNA binding whereas a redox inactive Trx-1 has no effect on Sp1 DNA binding.Sp1 has been implicated in vascular endothelial growth factor regulation and we have shown that Trx-1 expression results in increased hypoxic VEGF expression and increased tumor permeability in vivo. Trx-1 overexpression results in an increase in VEGF expression that is dependent upon Sp1, as inhibition of Sp1 expression with siRNA prevented the induction of VEGF expression by Trx-1. These results suggest that Trx-1 increases VEGF expression under normoxic conditions through a redox dependent increase in the DNA binding of the Sp1 transcription factor. VEGF regulation by Sp1 could increase angiogenesis in relatively perfused areas contributing to the stimulation of tumor growth by Trx-1.We hypothesized that Trx-1 regulation of Sp1 may be part of the mechanism of Trx-1 induction of cellular growth. Sp1 regulates many genes involved in cellular growth including epidermal growth factor receptor (EGFR) and insulin-like growth factor I receptor (IGF-IR). These two growth factor receptors are important for cellular growth and have been shown to be important therapeutic targets for cancer treatment. We report that treatment with the Trx-1 inhibitor PX-12 results in decreased Sp1 DNA binding as well as decreased Sp1 activation and transactivation of VEGF, EGFR, and IGF-IR. These results indicate that Trx-1 promotes cellular growth and survival, in part, through the redox regulation of Sp1 responsive growth genes EGFR and IGF-IR. Inhibition of Trx-1, via PX-12, results in a decrease in EGFR and IGF-IR expression and suggests a new mechanism by which Trx-1 inhibition is clinically effective for treating cancer.
4

Implication du système thiorédoxine dans la régulation des phosphatases CDC25 dans des cellules de cancer du sein en condition de stress oxydant / Involvement of thioredoxine system in CDC25 phosphatase regulation in breast cancer cells in oxidative stress condition

Beillerot, Adeline 08 November 2011 (has links)
De récentes études suggèrent que la régulation des phosphatases par le peroxyde d’hydrogène pourrait jouer un rôle important dans la signalisation cellulaire. Dans les cellules cancéreuses qui possèdent un statut redox souvent pro-oxydant, ce mécanisme de régulation pourrait être crucial pour la prolifération tumorale. Les phosphatases CDC25 (A, B et C) sont des régulateurs de la progression du cycle cellulaire. Sohn et Rudolph ont montré que les CDC25B et C peuvent être inactivées par le peroxyde d’hydrogène et réactivées en présence du système thiorédoxine/thiorédoxine réductase (trx/trxR), in vitro. L’existence d’une telle régulation dans des cellules cancéreuses pourrait ouvrir de nouvelles voies thérapeutiques puisqu’une inhibition des trxR ou des trx pourrait induire une inhibition des CDC25 et ainsi prévenir la croissance tumorale. Après avoir vérifié que CDC25A était également sensible au peroxyde d’hydrogène et réactivable in vitro par le système trx/trxR, les effets du peroxyde d’hydrogène et de deux inhibiteurs du système trx/trxR, l’Auranofine et l’Acroléine, ont été testés sur des lignées d’adénocarcinome mammaire humain (MCF7 et MDA-MB 231). Ces deux lignées présentent des niveaux d’expression variables pour la trx1. Dans les deux types de cellules, H2O2 induit un arrêt du cycle cellulaire malgré l’absence d’inhibition totale des CDC25. La conservation de l’état de phosphorylation des CDK lors de ce traitement témoigne donc de l’existence d’un système protecteur efficace pour ces phosphatases. L’inhibition totale des trxR par l’Auranofine engendre des effets cytotoxiques et une production de peroxydes dans les deux lignées. Il en est de même pour les cellules MDA-MB 231 traitées par l’Acroléine alors que les cellules MCF7 sont totalement résistantes à cette molécule. Le traitement des cellules par l’Auranofine induit un stress oxydant modéré car il n’altère pas le taux intracellulaire de glutathion, n’induit pas d’oxydation des trx1 et ne modifie pas la répartition des cellules dans le cycle cellulaire. Toutefois, ce traitement induit des cassures de l’ADN qui peuvent expliquer la cytotoxicité de ce composé. L’acroléine au contraire provoque, dans les cellules MDA-MB 231, une importante déplétion en glutathion associé à une oxydation majeure des trx1 et à un arrêt du cycle cellulaire. Ce dernier ne semble toutefois pas dû à une hyper-phosphorylation des CDK, ce qui suggère qu’une altération complète du système trx/trxR n’induit pas une inhibition totale des CDC25. Afin d’apporter des éléments nouveaux pour la compréhension des mécanismes de régulation redox des CDC25 et du cycle cellulaire dans les cellules de cancer du sein, nous avons ensuite étudié les impacts d’une surexpression de la Mn-SOD dans les cellules MCF7 puisque ces dernières sous-expriment cette protéine par rapport aux cellules MDA-MB 231. Les résultats obtenus révèlent que la répartition des cellules dans le cycle cellulaire et la phosphorylation des CDK ne sont pas sensibles à ce changement d’expression. Dans ce travail nous avons donc pu mettre en évidence que le rôle des CDC25 dans la régulation du cycle cellulaire n’est pas dépendant de l’état de fonctionnalité du système trx/trxR ou du niveau d’expression des Mn-SOD mais qu’il existe un système protecteur puissant qui permet de maintenir au moins en partie l’activité de déphosphorylation des CDC25 en milieu pro-oxydant dans les cellules de cancer du sein / Recent studies suggest that the regulation of phosphatases by hydrogen peroxide may play an important role in cell signaling. In cancer cells, which often possess a pro-oxidative redox state, this regulation could be essential for tumor growth. CDC25 phosphatases (A, B and C) are key regulators of cell cycle progression. Sohn and Rudolph have shown that CDC25B and C are inactivated by hydrogen peroxide and reactivated by the thioredoxin/thioredoxin reductase system (trx/trxR), in vitro. Such regulation in cancer cells could open new therapeutic avenues since the inhibition of trxR or trx could induce a CDC25 inhibition and so prevent tumor cell multiplication. After verifying that CDC25 activity is sensitive to H202 and could be restored by trx/trxR system in vitro, the effects of hydrogen peroxide and that of two trx/trxR inhibitors (Auranofin and Acrolein) was tested on human breast adenocarcinoma cells (MCF7 and MDA-MB 231). These two cell lines exhibit differential expression level for trx1. In both cell lines, H202 could induce a cell cycle arrest in spite of the lack of a full CDC25 inhibition. The maintenance of the CDK phosphorylation state suggests that an efficient protective system exists for these phosphatases. The total inhibition of trxR by Auranofin led to cytotoxic effects and peroxide production in both cell lines. Similar results were obtained for MDA-MB 231 cells treated with Acrolein while MCF7 cells were found to be resistant to this compound. Auranofin could trigger a moderate oxidative stress in treated cells without affecting intracellular GSH content, trx1 oxidation and cell cycle distribution. However, this treatment could trigger double-strand DNA breaks, which could explain the cytotoxicity of Auranofin. Conversely, Acrolein could provoke a strong GSH depletion associated with a full oxidation of trx1 and a cell cycle arrest in MDA-MB 231 cells. Nevertheless, this cell cycle disruption was not due to CDK hyper-phosphorylation, suggesting that a total inhibition of the trx/trxR system does not trigger a full CDC25 inhibition. Furthermore, in order to bring additional knowledge about CDC25 and cell cycle oxidative regulation in breast cancer cells, we have studied the effects of the Mn-SOD over-expression in MCF7 cells. In this cell line, Mn-SOD expression level was found to be lower than in MDA-MB 231 cells. Our results showed that the cell cycle distribution and CDK phosphorylation are not affected by Mn-SOD over-expression. In conclusion, we have shown in this work that the CDC25 function in cell cycle regulation is independent of both a functional trx/trxR system and Mn-SOD expression level but that, under pro-oxidative conditions, a potent protective system maintains at least partially CDC25 dephosphorylation activity in breast cancer cells
5

Examining muscle activation for Hang Clean and three different TRX Power Exercises : A validation study

Carbonnier, Anders, Martinsson, Ninni January 2012 (has links)
Background: Resistance training has proven to increase athletic performance, traditionally barbell training and Olympic Lifting have been used for this purpose. Sling training has recently been developed as a complement or substitution to traditional resistance training. Research has shown an increase in sport specific athletic performance and core stability with sling training. TRX Suspension Trainer is a newly developed sling training tool and to date no independent research has been done with the TRX. Purpose: To examine and compare muscle activation using TRX and the Olympic Lifting movement Hang Clean. Methods: 32 senior high school male soccer players participated in the study. Surface electromyographic (sEMG) data were collected on mm.erector spinae (back), m.gluteus maximus (glutes), m.vastus lateralis (quadriceps), m.semitendinosus (hamstrings) and m.gastrocnemius caput laterale (calf). Surface EMG data was collected when the subjects performed five different exercises, Hang Clean, TRX Squat Jump, TRX Front Squat and TRX Power Pull. In addition a Squat Jump was used as reference. Results: A similar muscle activation was found between Hang Clean (674 µV), TRX Squat Jump (684 µV) and TRX Front Squat (691 µV). TRX Power Pull showed the highest activation for mm.erector spinae and m.gluteus maximus but the lowest when comparing total muscle activation for all measured muscles. Conclusion: The similar amount of muscular activation for Hang Clean, TRX Squat Jump and TRX Front Squat indicates that the TRX Suspension Trainer can be used as a complement, for experienced athletes, or a substitution, for novice athletes, to traditional strength training. Coaches and athletic trainers should acknowledge the need and the importance of resistance training for athletic performance.
6

Подвесной и ротационный тренинг в фитнесе как способ безопасной и эффективной функциональной тренировки для коррекции веса : магистерская диссертация / Suspension and rotational training in fitness as a way of effective and safe functional training for weight correction

Григорьев, П. А., Grigorev, P. A. January 2018 (has links)
The dissertation research is devoted the impact of functional training with suspension and rotation of equipment for the weight correction of the visitors are middle aged (45-50 years) in the fitness club. Got results from the use of this equipment in order the weight loss people seeking to lose weight. / Диссертационное исследование посвящено рассмотрению влияния функциональной тренировки с помощью подвесного и ротационного оборудования на коррекцию веса у посетителей среднего возраста (45-50 лет) в фитнес клубе. Получены результаты использования этого оборудования в целях коррекции веса у людей, стремящихся к похудению.
7

Determination of gp120 <em>&</em> Trx80 dependent production of hydrogen peroxide in cell free <em>&</em> cell-dependent systems

Alam, Sadaf Sakina January 2009 (has links)
<p>Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), a reactive oxygen specie (ROS), is most commonly associated with oxidative stress causing cytotoxic effects on living cells. Oxidative stress has been implicated in various conditions including neurodegenerative diseases, autoimmune diseases and cancer. In addition H<sub>2</sub>O<sub>2 </sub>is produced as a defense mechanism against pathogens, as being released by activated phagocytes.<em> </em>In recent years, H<sub>2</sub>O<sub>2</sub> has become established as an important regulator of signal transduction in eukaryotic cells. Hydrogen peroxide is generated both intracellularly and extracellularly in response to various stimuli including cytokines and growth factors. There are different mechanisms by which H<sub>2</sub>O<sub>2</sub> is generated, facilitating signal transduction in cells; through NOX-system in miyochondria, via singlet oxygen, receptor/ligand interaction or by redox active metal ions. The HIV glycoprotein 120 (gp120) is associated with HIV dementia and it is known as a neurotoxin that causes neuronal damage. It has been proposed that free radicals may be involved in the pathogenesis caused by gp120. In addition the truncated form of thioredoxin (Trx80) is known to stimulate HIV replication in HIV infected cells, however, the exact mechanism is not known. A possible way both proteins may mediate their activity is by inducing H<sub>2</sub>O<sub>2</sub> production. The aim of this study was to investigate H<sub>2</sub>O<sub>2</sub> production induced by the proteins gp120 and Trx80. In order to detect H<sub>2</sub>O<sub>2</sub> production an assay based on the fluorescent compound Amplex Red, was established. The assay was used to detect H<sub>2</sub>O<sub>2</sub> released by gp120 and Trx80 in a cell-free environment, in a cell-system and in the presence of metal ions (copper ions) with a physiological reductant (ascorbate). We did not detect H<sub>2</sub>O<sub>2</sub> production induced by gp120 and Trx80 respectively, using our assay, however, other ROS such as hydroxyl radicals may have been generated although they were not detectable with our method. Hence, further studies are needed in order to fully understand how gp120 and Trx80 mediate their activity.</p>
8

Determination of gp120 &amp; Trx80 dependent production of hydrogen peroxide in cell free &amp; cell-dependent systems

Alam, Sadaf Sakina January 2009 (has links)
Hydrogen peroxide (H2O2), a reactive oxygen specie (ROS), is most commonly associated with oxidative stress causing cytotoxic effects on living cells. Oxidative stress has been implicated in various conditions including neurodegenerative diseases, autoimmune diseases and cancer. In addition H2O2 is produced as a defense mechanism against pathogens, as being released by activated phagocytes. In recent years, H2O2 has become established as an important regulator of signal transduction in eukaryotic cells. Hydrogen peroxide is generated both intracellularly and extracellularly in response to various stimuli including cytokines and growth factors. There are different mechanisms by which H2O2 is generated, facilitating signal transduction in cells; through NOX-system in miyochondria, via singlet oxygen, receptor/ligand interaction or by redox active metal ions. The HIV glycoprotein 120 (gp120) is associated with HIV dementia and it is known as a neurotoxin that causes neuronal damage. It has been proposed that free radicals may be involved in the pathogenesis caused by gp120. In addition the truncated form of thioredoxin (Trx80) is known to stimulate HIV replication in HIV infected cells, however, the exact mechanism is not known. A possible way both proteins may mediate their activity is by inducing H2O2 production. The aim of this study was to investigate H2O2 production induced by the proteins gp120 and Trx80. In order to detect H2O2 production an assay based on the fluorescent compound Amplex Red, was established. The assay was used to detect H2O2 released by gp120 and Trx80 in a cell-free environment, in a cell-system and in the presence of metal ions (copper ions) with a physiological reductant (ascorbate). We did not detect H2O2 production induced by gp120 and Trx80 respectively, using our assay, however, other ROS such as hydroxyl radicals may have been generated although they were not detectable with our method. Hence, further studies are needed in order to fully understand how gp120 and Trx80 mediate their activity.
9

Real-Time Imaging and Measurement of Compartmentalized Redox Shifts Using Novel Redox-Sensitive Biosensors: Implications in Developmental Toxicology

Davies, Brandon Mitchell 07 April 2023 (has links) (PDF)
Glutathione (GSH) is a small antioxidant in the body and exists in large quantities compared to other antioxidants. The GSH redox state (Eh) helps developmental processes, however, when the GSH Eh is disrupted, cells may undergo significantly poor developmental pathways, possibly leading to long-lasting damages. Similarly, NADPH and Thioredoxin redox states can have a major impact on cellular function, viability, and response to both endogenous and exogenous toxicants. Subcellular, compartmentalized redox environments during normal or perturbed situations, specifically in the cytosol, mitochondria, and nucleus, are not well understood. Here, using the P19 neurogenesis model of cellular differentiation, the kinetics of subcellular H2O2 availability and GSH/GSSG and NADPH/NADP+ redox shifts were evaluated following oxidant exposure. Additionally, modified mouse embryonic fibroblasts (MEFs) were used to observe redox changes and protective mechanisms when major antioxidative pathways are inhibited, mainly those involving the GSH/GSSG and Trxred/Trxox pathways. Overall, treated undifferentiated cells showed a greater degree and duration of both H2O2 availability and GSH/GSSG and NADPH/NADP+ disruption throughout all compartments than differentiated neurons. Pretreatment with an Nrf2 inducer prevented H2O2-induced effects in all compartments of undifferentiated cells. Additionally, MEF cells without either GSH or Trx showed a greater degree and duration of GSH/GSSG and Trxred/Trxox disruption throughout the cytosol and nucleus when compared to normal functioning cells. Disruption of redox-sensitive developmental pathways is likely stage-specific, where cells that are less differentiated and/or are actively differentiating are most affected. Undifferentiated cells are more susceptible to oxidant-induced redox dysregulation but are protected through prior Nrf2 induction, which appears to preserve developmental programs and diminish the potential for poor developmental outcomes. The GSH and Trx antioxidant pathways converge to protect the cell, while cells that are missing one pathway or the other may undergo damaging developmental outcomes.
10

Eigenschaften, Funktionen und Interaktionen des Glutaredoxin S17 aus Arabidopsis thaliana

König, Nicolas 15 January 2013 (has links)
Glutaredoxine wie auch Thioredoxine gehören der großen Proteinfamilie der Redoxine an. Das in dieser Arbeit näher untersuchte Glutaredoxin S17 (GRXS17) besteht aus einer Thioredoxin (Trx)- und bis zu drei Glutaredoxin (Grx)-Homologie-Domänen (HD). Es ist in ähnlicher Zusammensetzung in allen eukaryotischen und in vielen prokaryotischen Organismen unter unterschiedlichen Namen zu finden. Der Aufbau aus einer Trx-HD und drei Grx-HD kommt nur in höheren Pflanzen vor. In dieser Arbeit wurde das GRXS17 aus A. thaliana (AtGRXS17) sowohl durch computerbasierte Promotoranalysen als auch durch in vitro-Protein-Interaktionsstudien mit Transkriptionsfaktoren und Kinasen in Verbindung gebracht, die an Differenzierungsprozessen wie z.B. der Blühinduktion und/ oder an der Blütenbildung beteiligt sind. Mittels Bimolekularer Fluoreszenzkomplementation (BiFC) wurden Interaktionen von AtGRXS17 mit der Kinase At1g50570 und dem CCAAT-Transkriptionsfaktor NF-YC11 (At3g12480) verifiziert, welche zuvor bereits mittels massenspektrometrischer Analysen von pulldown-Versuchen identifiziert worden waren. Die drei Grx-HD des AtGRXS17-Proteins können [2Fe-2S]-Cluster einlagern (Kooperation mit C. Berndt, Karolinska Institut, Schweden). Eine regulative Funktion auf Transkriptebene, wie sie für das zu AtGRXS17 homologe GRX4 aus Saccharomyces cerevisiae (ScGRX4) durch die Interaktion mit dem CCAAT-Transkriptionsfaktor PHP4 in Abhängigkeit vom [2Fe-2S]-Cluster-Status des ScGRX4 stattfindet, ist daher denkbar. T DNA-Insertions-Mutanten im AtGRXS17-Gen generieren unter Langtag-Bedingungen (LT) verschiedene Differenzierungs-Phänotypen, während die Pflanzen unter Kurztag-Bedingungen (KT) in ihrer Entwicklung keine Abweichungen vom WT aufweisen. Der auffälligste dieser LT-Phänotypen zeigt eine verspätete Blühinduktion, die mit einem blütenlosen ersten Spross (PIN-like-Phänotyp) einhergeht. Erhöhte Lichtintensitäten verzögern die Blühinduktion weiter und lösen unterschiedliche stark ausgeprägte Entwicklungsstörungen in allen Blüten aus. Verschiedene, ebenfalls an der Blühinduktion beteiligte Vertreter der NF-Y-Transkriptionsfaktoren bilden mit CONSTANS (CO) einen Transkriptionsfaktor-Komplex zur Initiation der Transkription von FLOWERING LOCUS T (FT), dessen Genprodukt aus dem Blatt über das Phloem in den Vegetationskegel transportiert wird. Dort löst der Transkriptionsfaktor FT mit weiteren Transkriptionsfaktoren die Blühinduktion aus. Die Interaktion von AtGRXS17 mit dem NF YC11 und die Funktionsweise dieser Transkriptionsfaktor-Familie legen nahe, dass AtGRXS17 an regulativen Prozessen der Transkription von FT und somit an der Blühinduktion beteiligt ist. In 35S::AtGRXS17-Komplementations-Linien sind alle beobachteten Phänotypen der AtGRXS17-KO-Pflanzen behoben. Gibberellinsäure-Behandlungen an den KO-Pflanzen schwächen die Phänotypen, die bei Blühinduktion und Blütenbildung auftreten, ab. Vernalisierung unter LT-Bedingungen revertiert den Phänotyp der KO-Mutante vollständig. Da diese Behandlungen, die die Phänotypen des AtGRXS17 revertieren können, Mechanismen betreffen, die der Induktion durch die Photoperiode (LT) nachgeschaltet sind, ist der Wirkort von AtGRXS17 im Blühinduktionsweg durch LT-Bedingungen belegt.

Page generated in 0.0254 seconds