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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.
1

Η επίδραση των κυτταροκινών/ορμονών σε λιπώδη ιστό παχύσαρκων και φυσιολογικών παιδιών: In vitro συγκριτική μελέτη

Καρβέλα, Αλεξία 25 January 2012 (has links)
Εισαγωγή: Η παιδική παχυσαρκία αποτελεί μία επιδημία του σύγχρονου δυτικού κόσμου και ορίζεται λειτουργικά ως η υπέρμετρη αύξηση του λιπώδους ιστού. Η παχυσαρκία αποτελεί ανεξάρτητο παράγοντα κινδύνου για την ανάπτυξη μίας πληθώρας συνοσηροτήτων όπως την αντίσταση στην ινσουλίνη, το σακχαρώδη διαβήτη τύπου 2, καρδιοαγγειακά νοσήματα και μεταβολικό σύνδρομο. Ο λιπώδης ιστός είναι ένα παρακρινές και ενδοκρινές όργανο, το οποίο μέσω της έκκρισης κυτταροκινών και φλεγμονογόνων παραγόντων έχει την ικανότητα να ρυθμίσει το ενεργειακό ισοζύγιο του οργανισμού. Η αντιπονεκτίνη μία από τις πιο σημαντικές κυτταροκίνες του λιπώδους ιστού, μέσω των υποδοχέων της AdipoR1 και AdipoR2, ενεργοποιεί την ινσουλινοεπαγώμενη πρόσληψη της γλυκόζης από το λιποκύτταρο, ενώ έχει αντι-φλεγμονώδης και αντι-αθηρωματική δράση σε άλλους ιστούς του οργανισμού. Ο PPAR-γ, ανήκει στην υπερ-οικογένεια των πυρηνικών υποδοχέων PPARs (peroxisome proliferative-activated receptors) και είναι ένας μεταγραφικός παράγοντας, ο οποίος σε ανταπόκριση στα κυκλοφορούντα ελεύθερα λιπαρά οξέα, ενεργοποιεί τη διαφοροποίηση των προλιποκυττάρων σε ώριμα λιποκύτταρα μικρού μεγέθους με πολλά λιποσταγονίδια. Το PPAR-γ μέσω της ενεργοποίησης του από τους ενδογενείς υποκαταστάτες του, τις θειαζολιδινεδιόνες, επάγει την ινσουλινοευαισθησία και αυξάνει την έκφραση της αντιπονεκτίνης. Τα ενδοκανναβινοειδή, μέσω των υποδοχέων τους CB1 και CB2, ρυθμίζουν την όρεξη στο κεντρικό νευρικό σύστημα, ενώ μπορούν να ενεργοποιήσουν περιφερικά τη λιπογένεση και να μειώσουν τη γονιδιακή έκφραση της αντιπονεκτίνης. Τα ενδοκανναβινοειδή βρίσκονται υπερενεργοποιημένα σε ενήλικες παχύσαρκους, ενώ τα επίπεδα της αντιπονεκτίνης μειώνονται σημαντικά. Σκοπός: Να μελετηθούν τα επίπεδα έκφρασης του AdipoR1, του PPAR-γ, του CB1 και των ενζύμων των ενδοκανναβινοειδών FAAH και DAGL-α, σε λεπτόσωμα και παχύσαρκα προεφηβικά παιδιά και να συσχετιστούν με τα κυκλοφορούντα επίπεδα της αντιπονεκτίνης και της ινσουλίνης. Μεθοδολογία: Για το σκοπό αυτό αναπτύχθηκαν πρωτογενείς καλλιέργειες προλιποκυττάρων και ώριμων λιποκυττάρων από βιοψίες κοιλιακού υποδόριου λιπώδους ιστού 17 παχύσαρκων (BMI>95%) και 36 λεπτόσωμων (BMI<85%) προεφηβικών παιδιών. Τα παιδιά χωρίστηκαν σε δύο ηλικιακές ομάδες, ομάδα Α: 2μηνών-7 ετών και ομάδα Β: 9-12 ετών. Η γονιδιακή και πρωτεϊνική έκφραση του AdipoR1, PPAR-γ και CB1 μελετήθηκαν με τη μέθοδο RT-PCR και Western Immunoblotting. Επίσης, η γονιδιακή έκφραση των ενζύμων των ενδοκανναβινοειδών FAAH και DAGL-α, μελετήθηκαν με Real-Time PCR. Τα κυκλοφορούντα επίπεδα της ολικής και HMW αντιπονεκτίνης όπως και της ινσουλίνης μετρήθηκαν με ELISA, ενώ υπολογίστηκε ο δείκτης ινσουλινοαντίστασης HOMA-IR και μετρήθηκε η περίμετρος κοιλίας σε κάθε παιδί. Αποτελέσματα: Η πρωτεϊνική έκφραση του AdipoR1 βρέθηκε μειωμένη στα προλιποκύτταρα και ώριμα λιποκύτταρα των μικρότερων παχύσαρκων παιδιών της ομάδας Α, σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους. To PPAR-γ βρέθηκε αυξημένο στα ώριμα λιποκύτταρα των λεπτόσωμων και παχύσαρκων παιδιών, σε σύγκριση με τα προλιποκύτταρά τους, ενώ ήταν και σημαντικά αυξημένο στα ώριμα λιποκύτταρα των μικρότερων παχύσαρκων παιδιών, σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους. Ο υποδοχέας των ενδοκανναβινοειδών, CB1, ήταν σημαντικά μειωμένος στα ώριμα λιποκύτταρα των παχύσαρκων παιδιών και των δύο ηλικιακών ομάδων, σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους, ενώ παρουσίασε μία σημαντική αύξηση με την ηλικία. Επιπρόσθετα, το ένζυμο αποδόμησης FAAH (για την ανανδαμίδη) μειώθηκε με την ηλικία στα μεγαλύτερα λεπτόσωμα παιδιά της ομάδας Β, ενώ στα μεγαλύτερα παχύσαρκα παιδιά ήταν αυξημένο σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους. Το ένζυμο βιοσύνθεσης DAGL-α (για το 2-AG) βρέθηκε αυξημένο στα μεγαλύτερα λεπτόσωμα και παχύσαρκα παιδιά της ομάδας Β σε σύγκριση με τα λεπτόσωμα και παχύσαρκα παιδιά της ομάδας Α. Η ινσουλίνη και το HOMA-IR ήταν σημαντικά αυξημένα στα μεγαλύτερα παιδιά, λεπτόσωμα και παχύσαρκα, σε σύγκριση με τα μικρότερα παιδιά. Η HMW αντιπονεκτίνη βρέθηκε μειωμένη στα λεπτόσωμα και παχύσαρκα παιδιά της ομάδας Β σε σύγκριση με τα αντίστοιχα παιδιά της ομάδας Α, ενώ ήταν σημαντικά αυξημένη στα μικρότερα παχύσαρκα παιδιά σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους. Η περίμετρος κοιλίας ήταν σημαντικά αυξημένη στα μεγαλύτερα παχύσαρκα αγόρια σε σύγκριση με τα αντίστοιχα λεπτόσωμά τους. Συμπεράσματα: Η μειωμένη έκφραση του CB1 και η αυξημένη έκφραση του PPAR-γ στα μικρότερα παχύσαρκα προεφηβικά παιδιά της ομάδας Α, σε συνάφεια με τα αυξημένα επίπεδα της HMW αντιπονεκτίνης, πιθανόν να αντικατοπτρίζουν έναν προστατευτικό μηχανισμό ελεγχόμενης λιπογένεσης και διατήρησης της ινσουλινοευαισθησίας στα παιδιά αυτά που ήδη παρουσιάζουν μειωμένα επίπεδα έκφρασης του υποδοχέα της αντιπονεκτίνης, AdipoR1. Επιπλέον, τα μειωμένα επίπεδα της HMW αντιπονεκτίνης και τα αυξημένα επίπεδα της ινσουλίνης στα μεγαλύτερα παιδιά πιθανόν απεικονίζει την προετοιμασία των παιδιών αυτών για την «φυσιολογική» ινσουλινοαντίσταση της εφηβείας. Η αύξηση των ενζύμων FAAH και DAGL-α στα μεγαλύτερα παχύσαρκα παιδιά της ομάδας Β, μπορεί έμμεσα να μας δείχνει ότι τα επίπεδα της ανανδαμίδης στα παιδιά αυτά είναι μειωμένα, ενώ τα επίπεδα του ενδοκανναβινοειδούς 2-AG αυξάνονται, θέτοντας πιθανόν τα παχύσαρκα παιδιά σε μεγαλύτερο κίνδυνο για λιπογένεση. Η μειωμένη έκφραση του CB1 στα μεγαλύτερα παχύσαρκα παιδιά όμως, μπορεί να απεικονίζει είτε την προσπάθεια του οργανισμού να περιορίσει την λιπογένεση στα παιδιά αυτά, που ήδη βρίσκονται σε κίνδυνο λόγω της παχυσαρκίας τους, είτε αντικατοπτρίζει τη μειωμένη ικανότητα του υποδόριου λιπώδους ιστού να αποθηκεύσει λίπος αυξάνοντας τον κίνδυνο εναπόθεσης λίπους ενδοκοιλιακά, το οποίο μπορεί να διαταράξει την ενεργειακή ισορροπία του οργανισμού τους προκαλώντας διαταραγμένη ανοχή στη γλυκόζη. / Introduction: Childhood obesity is the new epidemic of the western world and reflects the excessive storage of body fat. Obesity is a risk factor for the development of metabolic comordities like insulin resistance, diabetes mellitus type 2, cardiovascular diseases and metabolic syndrome. Adipose tissue is an endocrine and paracrine organ, which through the secretion of adipokines and pro-inflammatory molecules it can regulate the body’s energy homeostasis. Adiponectin is one of the most important secreted adipokines of adipose tissue and through its AdipoR1 and AdipoR2 it can activate the insulin-dependent glucose uptake of adipocytes. In addition, adiponectin has anti-inflammatory and anti-atherogenic action in other peripheral tissues of the body. PPAR-γ belongs to the family of nuclear receptors PPARs (peroxisome proliferative-activated receptors) and it is a transcription factor, which responds to circulating Free Fatty Acids activating the preadipocyte differentiation into small multilocular mature adipocytes. PPAR-γ through its activation from its endogenous ligands, the thiazolidenidions, can regulate the body’s insulin sensitivity and can increase the transcription of adiponectin. The endocannabinoids, through their receptors CB1 and CB2, can regulate food intake via their central nervous system action, they activate lipogenesis in the periphery and reduce the gene expression of adiponectin. The endocannabinoids are found to be upregulated in adult obesity, whereas adiponectin levels are decreased. Aim: To study the expression of AdipoR1, PPAR-γ, CB1 and the endocannabinoid enzymes FAAH and DAGL-α, in prepubertal lean and obese children in relation to their adiponectin and insulin levels in their blood serum. Materials & Methods: Primary cultures of preadipocytes and mature adipocytes were developed from surgical biopsies of abdominal subcutaneous adipose tissue of 17 obese (BMI>95%) and 36 lean (BMI<85%) prepubertal children. The gene and protein expression of AdipoR1, PPAR-γ and CB1 were investigated by RT-PCR and western immunoblotting. The gene expression of the endocannabinoid enzymes FAAH and DAGL-α were studied by Real-Time PCR. Total and HMW adiponectin together with insulin were measured in blood serum by ELISA, whereas the insulin resistance index HOMA-IR was estimated and waist circumference was measured in every child. Results: The protein expression of AdipoR1 was significantly decreased in the preadipocytes and the mature adipocytes of the younger obese prepubertal children of group A when compared to their respective lean. PPAR-γ was increased in the mature adipocytes of all the children in comparison to their respective preadipocytes, whereas it was significantly increased in the mature adipocytes of the younger obese children compared to their respective lean. The endocannabinoid receptor, CB1, was significantly decreased in the mature adipocytes of the obese children in both age groups, when compared to their respective lean, whereas it increased with age in the older lean children. Furthermore, the degradation enzyme FAAH (for anandamide) decreased significantly with age in the older lean prepubertal children of group B, in comparison to the younger lean and it was significantly increased in the older obese children in comparison to their respective lean. The biosynthetic enzyme DAGL-α (for 2-AG) was found significantly increased in the older lean and obese prepubertal children of group B when compared to the younger children of group A. Insulin and the HOMA-IR were significantly increased in the older children, both lean and obese in comparison to their respective younger children. HMW adiponectin was decreased in the older prepubertal children of group B in comparison to group A, whereas it was significantly increased in the younger obese children of group A when compared to their respective lea. Waist circumference was significantly increased in the older obese boys when compared with their respective lean. Conclusions: The decreased expression of CB1 together with the increased expression of PPAR-γ and the increased levels of HMW adiponectin in the younger obese prepubertal children of group A, possibly reflects their body’s attempt to further limit their pathologic lipogenesis and to maintain normal insulin sensitivity in these obese children, who already have decreased AdipoR1 expression. In addition, the decreased HMW adiponectin levels and the increased insulin in the older children could be indicative of their “physiological” insulin resistance during puberty. The increased expression of the enzymes FAAH and DAGL-α in the older obese prepubertal children of group B, may indirectly demonstrate that anandamide is decreased and 2-AG is increased in these children, possibly pre-empting them for increased lipogenesis. The decreased expression of CB1 in the older obese children may also indicate either the body’s attempt to further limit lipogenesis since they are already at risk due to their obesity or it reflects their decreased ability of storing fat in their subcutaneous adipose tissue, increasing the risk of visceral fat disposition that can disrupt their energy homeostasis and could possibly lead to the development of glucose intolerance.
2

In vivo and in vitro studies of Salmon Pancreas Disease Virus (SPDV) in Atlantic salmon (Salmo salar L.)

Noguera, Patricia Alina January 2018 (has links)
Salmon Pancreas Disease Virus (SPDV) is the only viral species of the genus Alphavirus, family Togaviridae, affecting fish. SPDV induces two conditions historically recognised independently as Pancreas disease (PD) and Sleeping disease (SD), affecting Atlantic salmon (Salmo salar L) and rainbow trout (Oncorhynchus mykiss), respectively. Infection by SPDV can lead to clinical disease with characteristic acinar pancreatic necrosis and a range of myopathies of the skeletal and heart muscle. Mortality is not a necessary outcome of the disease and usually is not significant. However, affected fish stop eating and therefore present a reduced growth rate and the disease can also leave visible lesions at the fillet level that lead to downgrading at slaughter. SPDV can affect in the fresh and sea water environments, but a higher and most relevant impact reported in the latter. Historically, PD has posed a significant challenge to the Atlantic salmon farming industry in the UK, as well as in other salmon producing countries. This thesis was developed and conducted at Marine Scotland Science (MSS), the Scottish National Reference Laboratory, with the aim to contribute to knowledge gaps identified by the industry and research communities. The focus was on development and improvement of in vivo and in vitro infection models to assist with host pathogen interaction studies. In vivo work was to establish an experimental challenge model to induce SPDV infection in a more natural way than by intra-peritoneal (IP) injection. The first step involved selection of an infective SPDV isolate through a comparative IP challenge study. An infective isolate was then used to establish a co-habitation challenge model in "post smolts", the sea-water stage predominantly affected by PD. Additionally, during this experiment assessment of viral tissue tropism along time and potential intra-subtype differences in infectivity was undertaken. In vitro work accounted for the more innovative part of this thesis with the development, optimization and application of an ex vivo cardiac primary culture originated from Atlantic salmon embryos. While fish origin aggregates of self-contracting cardiomyocytes had been previously isolated and suggested as a robust tool on human biomedical research and pharmacological and toxicology testing, paradoxically very little has been done to explore the approach of ex vivo primary cultures as a disease model with the specific goal for health issues affecting fish. The work involved an adaptation and refinement to produce salmon cardiac primary cultures (SCPCs). Once this was achieved, SCPCs could be kept under laboratory conditions with minimal maintenance for periods up to 6 months. Following this work, SCPCs were successfully challenged with different SPDV isolates as well as another cardiotropic viral agent (Infectious Salmon Anaemia, ISA). The kinetics of SPDV and ISA viral infection and one element of the immune response (i.e. expression of mx gene) were studied. As part of this study, the comparative response of SCPCs of diverse genetic backgrounds (i.e. IPN resistant vs. IPN sensitive) was also assessed. Differences were observed, which highlights potential usefulness of SCPCs to examine genotype-based differences in response to viral disease. Finally, SCPCs were used to examine the SPDV infection cycle ultrastructure by transmission electron microscopy (TEM). This work resulted in novel insights on the replication cycle of SPDV, drawing from the extensive literature in mammalian alphavirus work. With SPDV and other virus associated myocarditis severely affecting Atlantic salmon aquaculture at present, I believe that the SCPCs model represents the most relevant contribution of this PhD.
3

Cultura de células embrionárias-simile de Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) para isolamento e cultivo de patógenos. / Tick embryonic-like cell culture of Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) for pathogen isolation and cultivation.

Daniella Aparecida Franze 24 February 2015 (has links)
Diversas linhagens de células de carrapatos já foram estabelecidas em outras regiões do mundo para isolamento de patógenos. O objetivo deste estudo é obter cultivos de células de Rhipicephalus sanguineus para testar o crescimento de alguns bioagentes. O primeiro capítulo trata do estabelecimento da linhagem celular e o segundo, do uso da linhagem como substrato para infecção de patógenos. Ovos de R. sanguineus foram preparados em meio L-15B e mantidos à 30 &deg;C. Quando as células se tornaram confluentes, as culturas foram propagadas e criopreservadas. O descongelamento foi bem sucedido a partir da terceira passagem e a identidade celular foi confirmada por sequenciamento utilizando o fragmento 16S rDNA mitocondrial. As células foram infectadas com Erhlichia canis, Leishmania infantum chagasi e Trypanosoma cruzi, sendo eficientes somente para E. canis. / Several lines of embryonic cells of ticks already been established in other regions of the world, and are used to isolate and propagate pathogens. The aim of this study, is to obtain cell cultures from Rhipicephalus sanguineus to test the growth of some bioagents.The first addressing consists of the establishment of the cells and the second, using the cell lineage as a substrate for the pathogens infection. The egg masses of R. sanguineus were prepared in L-15B medium and cultures were maintained at 30 &deg;C. When a confluent cellular monolayer was obtained, the cultures were passaged and frozen. Defrosting of cryopreserved cultures from the third passage was successful. Cell identity was confirmed by sequencing using 16S rDNA gene fragment. Cells were infected with Erhlichia canis, Leishmania infantum chagasi and Trypanosoma cruzi. Only for E. canis the cells of R. sanguineus were effective as a substrate for growth of this pathogen.
4

Cultura de células embrionárias-simile de Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) para isolamento e cultivo de patógenos. / Tick embryonic-like cell culture of Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) for pathogen isolation and cultivation.

Franze, Daniella Aparecida 24 February 2015 (has links)
Diversas linhagens de células de carrapatos já foram estabelecidas em outras regiões do mundo para isolamento de patógenos. O objetivo deste estudo é obter cultivos de células de Rhipicephalus sanguineus para testar o crescimento de alguns bioagentes. O primeiro capítulo trata do estabelecimento da linhagem celular e o segundo, do uso da linhagem como substrato para infecção de patógenos. Ovos de R. sanguineus foram preparados em meio L-15B e mantidos à 30 &deg;C. Quando as células se tornaram confluentes, as culturas foram propagadas e criopreservadas. O descongelamento foi bem sucedido a partir da terceira passagem e a identidade celular foi confirmada por sequenciamento utilizando o fragmento 16S rDNA mitocondrial. As células foram infectadas com Erhlichia canis, Leishmania infantum chagasi e Trypanosoma cruzi, sendo eficientes somente para E. canis. / Several lines of embryonic cells of ticks already been established in other regions of the world, and are used to isolate and propagate pathogens. The aim of this study, is to obtain cell cultures from Rhipicephalus sanguineus to test the growth of some bioagents.The first addressing consists of the establishment of the cells and the second, using the cell lineage as a substrate for the pathogens infection. The egg masses of R. sanguineus were prepared in L-15B medium and cultures were maintained at 30 &deg;C. When a confluent cellular monolayer was obtained, the cultures were passaged and frozen. Defrosting of cryopreserved cultures from the third passage was successful. Cell identity was confirmed by sequencing using 16S rDNA gene fragment. Cells were infected with Erhlichia canis, Leishmania infantum chagasi and Trypanosoma cruzi. Only for E. canis the cells of R. sanguineus were effective as a substrate for growth of this pathogen.
5

Morphogenesis in Drosophila melanogaster : an in vitro analysis

Scarborough, Julie January 2007 (has links)
The aim of this thesis was to investigate morphogenesis in the fruit fly Drosophila melanogaster using three in vitro tissue culture systems. Primary embryonic cultures derived from Drosophila melanogaster were used to study the effect of the moulting hormone ecdysone on cells in culture. The hypothesis was that the effect of ecdysone on these primary embryonic cells would parallel events which occur during metamorphosis in vivo and therefore the primary embryonic cultures could be used as an ‘in vitro’ model system. Transgenic fly lines expressing GFP were used to visualise and identify specific cell types and it was shown that cells in primary embryonic cultures respond to ecdysone morphologically. However due to the variability of cultures it was concluded that this culture system was not suitable for use as a model system. As defined cell types were observed the development of a protocol suitable for use with the primary embryonic culture system using dsRNA in order to demonstrate RNA interference was undertaken. Although this was unsuccessful, as cells in the primary embryonic cultures appeared to be resistant to dsRNA, some technical avenues remain to be explored. The Drosophila melanogaster cell line, Clone 8+, was used to investigate cell adhesion in tissue culture. Statistical analyses were carried out and it was established that derivatives of the parent cell line, Clone 8+, showed differential adhesion and proliferation characteristics. Analysis of microarray data was carried out in order to identify genes which may be responsible for the loss of cell adhesion in Clone 8+ cell lines and the potential roles of these genes in adhesion were discussed. A gene of interest, glutactin, was identified which may be responsible for loss of cell adhesion. Antibody staining was used to establish the expression of the protein glutactin in the Clone 8+ cell lines. The expression of glutactin suggested that the Clone 8+ cell line had maintained properties of the wing disc epithelial cell-type and disruption of cell polarity was considered as a possible mechanism. It was shown that f-actin colocalised with glutactin and the role of the cytoskeleton in glutactin secretion was discussed. It was concluded that glutactin was not responsible for loss of cell adhesion in the Clone 8+ cell lines. Further analysis of the microarray data revealed potential genes that could be responsible for the loss of cell polarity in the Clone 8+ cell lines and the possibility of cellular senescence was considered. It was hypothesised that the properties of adhesion and proliferation related to their ‘in vitro’ age. In the final investigation the movement of epithelial cells in Drosophila melanogaster third instar larval imaginal discs during morphogenesis was investigated. Firstly a lumen was identified in fixed imaginal disc tissue in association with cells expressing f-actin. This result was discussed in relation to the process of dorsal closure and wound healing. Further investigations involved live imaging of the dynamic process of evagination in the imaginal wing disc using transgenic flies expressing moesin-GFP. It was concluded that the lumen was not associated with the process of wound healing and it was concluded that the lumen appeared to be the mechanism directing peripodial epithelium contraction during morphogenesis of the imaginal wing disc. Dorsal closure and the process of invagination in relation to morphogenesis of the imaginal wing disc were discussed.
6

Objemově regulované aniontové kanály u astrocytů - in vitro and in situ analýza / Volume-regulated anion channels in astrocytes- in vitro and in situ analysis

Harantová, Lenka January 2012 (has links)
Astrocytes need to preserve constant volume in the face of osmolarity perturbations to function properly. To regain their original volume after hyposmotically induced swelling, they extrude intracellular electrolytes and organic osmolytes, such as inorganic ions, excitative amino acids or polyols, accompanied by osmotically driven water. This process is termed regulatory volume decrease and is ensured by various ion channels and transporters. Recently, much attention has been focused on the ubiquitous volume-regulated anion channels activated by cell swelling. VRACs are moderately outwardly rectifying with intermediary conductance, permeable to inorganic anions and organic osmolytes and sensitive to broad-spectrum anion channels blockers. Using patch-clamp technique we aimed to characterize VRACs in cultured cortical astrocytes isolated from neonatal Wistar rats and to elucidate the effect of intracellular Na+ on VRAC activity. In addition, we also intended to characterize these channels in situ in brain slices of 10 - 12 days old rats, focusing mainly on hippocampal astrocytes. To induce astrocytic swelling, we exposed astrocytes to hypotonic solution (250 mOsm). In agreement with previous findings, we showed that cultured cortical astrocytes activate VRAC currents upon exposure to hypotonic stress, which...
7

Aurora B Kinase-Inhibitor und Therapie mit elektrischen Feldern als neues adjuvantes Therapiekonzept in der Behandlung maligner Gliome

Bartmann, Paula 07 October 2020 (has links)
Das Glioblastom ist der häufigste hirneigene Tumor des Erwachsenen und mit einer 5-Jahres-Überlebensrate von weniger als 5 % eine der aggressivsten Hirntumorerkrankungen (Batash et al., 2017). Verbunden mit einer schlechten Prognose und geringen Remissionsraten ergibt sich die Notwendigkeit, bestehende Therapieoptionen zu optimieren und zu erweitern. Im Rahmen dieser Arbeit wurde das vor einigen Jahren entwickelte und aktuell in klinischen Studien angewandte Konzept der Therapie von Malignomen mit elektrischen Wechselfeldern, den sog. Tumor Treating Fields (TTFields), aufgegriffen. Basis der anti-tumoralen Wirkung der im Rahmen von Glioblastom-Studien applizierten TTFields bildet eine Tumor-spezifische Frequenz von 200 kHz sowie geringe Intensitäten, die einen nebenwirkungsarmen anti-mitotischen Effekt erzielen (Kirson et al., 2004; Kirson et al., 2007; Clark et al., 2017; Porat et al., 2017). Dieser resultiert sowohl aus alternierenden elektrischen Feldern, die während der Metaphase über eine Irritation des Dipolmoments von Tubulin-Untereinheiten die Assemblierung des Spindelapparates inhibieren, als auch aus inhomogenen elektrischen Feldern, die während der Telophase die Trennung der Tochterzellen behindern. Mit dieser Behandlungsoption konnten schon einige gute Ergebnisse für die Behandlung von Glioblastomen in klinischen Studien erreicht werden (Stupp et al., 2017). Eine weitere anti-mitotische Therapieoption stellt die Inhibierung der Aurora B Kinase mittels AZD1152 dar. Die Aurora B Kinase ist Teil des Chromosomal Passenger Complex (CPC), der bei Inhibierung der Kinase seine Kontrollfunktionen während der Mitose und Zytokinese nicht wahrnehmen kann. Diese fehlende Kontrolle führt zu Polyploidie, die einen Zelltod verursachen kann (Wiedemuth et al., 2016). Aufgrund dieses ähnlichen biologischen Hintergrundes wurde zu Beginn dieser Arbeit die Hypothese aufgestellt, dass eine kombinierte Therapie mittels TTFields und AZD1152 einen additiven zytotoxischen Effekt im Vergleich zur Monotherapie mit TTFields erzielen kann. Es konnte zunächst für die etablierte Zelllinie U87-MG ein signifikanter additiver Effekt in der Kombinationstherapie der TTFields mit AZD1152 im Vergleich zur alleinigen Therapie mittels TTFields nachgewiesen werden. Die mediane Tumorzellzahl konnte hierbei in der Kombinationstherapie um 60 % reduziert werden. Dieser additive Effekt konnte ebenfalls an zwei Primärkulturen reproduziert werden. Hierbei konnte die relative mediane Tumorzellzahl der Primärkultur HT18584 ebenfalls um 60 % in der Kombinationstherapie gesenkt werden. Diese tetraploide Zellreihe zeigte außerdem einen außergewöhnlich großen zytotoxischen Effekt bei der Behandlung mit AZD1152. Signifikant zeigte ebenso die Primärkultur HT12347 einen medianen Verlust von 56 % der Tumorzellen nach einer kombinierten Behandlung. Qualitativ und zellmorphologisch konnte mittels konfokaler Laser-Scanning- sowie Lichtmikroskopie die Akkumulation von mitotischen Defekten detektiert werden, die auch in den Monotherapien aber vor allem in der Kombinationstherapie zu finden waren. Die in der quantitativen Analyse gezeigte additive Zytotoxizität der Kombinationstherapie konnte hier nochmals visualisiert und bestätigt werden. Für eine klinische Phase I-Studie zur Überprüfung der Effektivität sollten zunächst weitere zellkulturtechnische Daten erfasst werden, um die Universalität der kombinierten Behandlung zu überprüfen. Weiterhin wäre die Entwicklung einer selektiven/lokalen Therapie mittels AZD1152 wünschenswert, um die Nebenwirkungen des Medikamentes abzumildern. Es sollte außerdem das im Rahmen dieser Arbeit detektierte sensitivere Ansprechen der tetraploiden Zelllinie HT18584 genauer untersucht werden, um eine potentiell prognostisch günstige Verbindung zwischen der Behandlung mit AZD1152 und tetraploiden Zellen herstellen zu können.:1 EINLEITUNG 1 1.1 Glioblastoma multiforme – Definition, Inzidenz und Ätiologie 1 1.1.1 Symptomatik und Diagnostik des Glioblastoms 2 1.2 Molekulare Klassifizierung 3 1.2.1 Primäre und sekundäre Glioblastome und einige allgemeine Marker 3 1.2.2 Der MGMT-Status 5 1.3 Der eukaryotische Zellzyklus und sequentielle Kontrollpunkte 6 1.3.1 Der Chromosomal Passenger Complex (CPC) 8 1.3.2 Die Familie der Aurorakinasen 9 1.4 Therapie maligner Gliome 10 1.4.1 Standardtherapie eines Glioblastoms 10 1.4.2 Tumor Treating Fields (TTFields) – Biologischer Effekt und Studienlage 11 1.4.3 Aurora Kinase-Inhibitoren 14 1.5 Zielstellung der Arbeit 15 2 METHODEN UND MATERIALIEN 17 2.1 Methoden 17 2.1.1 Zellkultivierung allgemein 17 2.1.2 Passagieren adhärenter Zellen 17 2.1.3 Kultivierung von primärem Patientenmaterial 18 2.1.4 Kryokonservierung und Rekultivierung eukaryotischer Zelllinien 18 2.1.5 Bestimmung der Lebendzellzahl mittels Neubauer-Zählkammer 19 2.1.6 Durchflusszytometrische Analyse 19 2.1.7 Bestimmung der Lebendzellzahl mittels Propidiumiodid (PI) 20 2.1.8 Durchflusszytometrische Immunphänotypisierung von Glioblastomzellen 20 2.1.9 In vitro-Applikation der Tumor Treating Fields (TTFields) 21 2.1.10 Titration der effektiven Aurora B Kinase-Inhibitorkonzentrationen mittels PI 22 2.1.11 Titration inhibitorischer Temozolomidkonzen-trationen mittels AlamarBlue-Assay 23 2.1.12 Konfokale Laser-Scanning-Mikroskopie 23 2.2. Materialien 25 2.2.1 Geräte 25 2.2.2 Chemikalien und Reagenzien 25 2.2.3 Lösungen 26 2.2.4 Medien 27 2.2.5 Kommerzielle Kits 28 2.2.6 Antikörper 28 2.2.7 Software 28 2.2.8 Statistik 29 2.2.9 Zelllinien 29 3 ERGEBNISSE 30 3.1 Wahl des Designs der Kontrollgruppen 30 3.2 Typisierung der verwendeten Primärkulturen 32 3.2.1 Befunde der Pathologie des Universitätsklinikums Dresden 33 3.2.2 Immunphänotypisierung der Primärkultur HT18584 34 3.2.3 Immunphänotypisierung der Primärkultur HT12347 35 3.3 Titrationen mit AZD1152 36 3.3.1 Titration mit AZD1152 für die Primärkultur HT18584 36 3.3.2 Titration mit AZD1152 für die Primärkultur HT12347 37 3.4 Kombinationstherapie mittels AZD1152 und TTFields 38 3.4.1 Quantitativer Effekt der Kombinationstherapie an U87-MG 39 3.4.2 Quantitativer Effekt der Kombinationstherapie an HT18584 40 3.4.3 Quantitativer Effekt der Kombinationstherapie an HT12347 41 3.4.4 Qualitativer Effekt der Kombinationstherapien 42 3.4.4.1 Die Kombinationstherapie mit U87-MG 43 3.4.4.2 Die Kombinationstherapie mit HT18584 44 3.4.5 Zytotoxischer Effekt der Kombinationstherapie an HT12347 45 3.5 Titrationen mit Temozolomid 47 3.5.1 Therapie mit Temozolomid an U87-MG 48 3.5.2 Therapie mit Temozolomid an Primärkulturen 48 4 DISKUSSION 52 4.1 Vorversuche 52 4.1.1 Wachstumsanalyse der Kontrollgruppen 52 4.1.2 Charakterisierung der Primärkulturen 53 4.2 Die neuen Behandlungsoptionen 54 4.2.1 Applikation der TTFields 54 4.2.2 Die Behandlung mit AZD1152 55 4.2.3 Die Kombinationstherapie 57 4.3. Die Behandlung mit Temozolomid (TMZ) 59 5 ZUSAMMENFASSUNG 62 LITERATURVERZEICHNIS 64 TABELLENVERZEICHNIS 73 ABBILDUNGSVERZEICHNIS 74 ABKÜRZUNGSVERZEICHNIS 75 ANHANG 77 Anhang 1: Einverständniserklärung der Patienten 77 Anhang 2: Erlaubnis zur Nutzung der Patientendaten der Pathologie 78 Anhang 3: Erklärungen zur Eröffnung des Promotionsverfahrens 79 Anhang 4: Erklärung über die Einhaltung gesetzlicher Vorgaben 81
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Telomerase and its reverse transcriptase subunit TERT : identification and oestrogenic modulation of telomerase transcription in two aquatic test species - European Purple Sea Urchin (Paracentrotus Lividus) and Rainbow Trout (Oncorhynchus Mykiss)

Brannan, Katla Jorundsdottir January 2012 (has links)
A plethora of naturally-produced steroid hormones, or artificial homologues of them, are being introduced into the aquatic and terrestrial environments each year. Two examples of these are the natural oestrogen 17-oestradiol (E2) and the oestrogen receptor antagonist, Bisphenol A (BPA), both of which target the ribonucleoprotein telomerase through upregulation of its telomerase reverse transcriptase component, TERT. The main objectives of this study were firstly to isolate and characterize the actual mRNA sequence for the telomerase catalytic subuninit, Tert, in rainbow trout (Oncorhynchus mykiss) (Walbaum, 1792) and European purple sea urchin (Paracentrotus lividus) (Lamarck, 1816), with the aim of developing qPCR assays for the amplification and quantification of Tert. Further objectives were to use these assays in controlled exposure studies to establish whether and to what extent the aforementioned chemicals regulate Tert transcription and by doing so further understand the mechanism of Telomerase gene expression and the extent to which environmental oestrogen can interfere. The initial step of sequence characterization and assay devlopment was successful in the case of rainbow trout where two possible splice variants of Tert mRNA are identified, omTertShort and omTertLong. Two qPCR assays were developed for the relative quantification of both of these splice variants in rainbow trout samples, the latter of these successfully amplifying its target in test samples. In order to demonstrate in vitro and in vivo modulation of telomerase activity and mRNA expression, early life-stages of rainbow trout and purple sea urchin, as well as rainbow trout hepatocytes, were exposed to a range of concentrations of E2 and BPA. Purple sea urchin embryos were exposed to 200, 20 and 2 ng E2/ml for 28 hours until they had reached the stage of pluteus larvaes. Rainbow trout embryos were exposed to 500, 20 and 0.1 ng E2/ml and 600 and 150 ng BPA/ml for 167 days from immediately after fertilization. Rainbow trout hepatocytes were exposed to 20 and 2 ng E2/ml for 48 hours. The results from this study show that telomerase activity as well as TERT mRNA expression can be significantly modulated by exposure to oestrogens and other oestrogenic chemicals. E2 concentrations as low as 20 ng/ml lead to an increase in telomerase activity early-life stages of purple sea urchin and upregulation in the transcription of Tert mRNA in unhatched rainbow trout embryos. BPA induced similar response (600 ng/ml) in hatched rainbow trout alevins larvae. Very high exposures to E2 (500 ng/ml) do however lead to downregulation of Tert mRNA in hatched alevins larvae. Differential regulatory response can be observed between different tissue types of 167 day old fry, with an upregulatory response observed at 0.1 ng E2/ml in liver and muscle tissues, but not in brain. Similarly, brain tissues were observed expressing significantly less mRNA than liver and muscle samples when exposed to BPA (150 ng/ml). It is evident that the previously observed link between environmental oestrogens and telomerase is also present in the two test species examined; purple sea urchin and rainbow trout.

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