| 1. |
- Edfeldt, Katarina, 1979-
(author)
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Small Intestinal Neuroendocrine Tumours : Genetic and Epigenetic Studies and Novel Serum Biomarkers
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Small intestinal neuroendocrine tumours (SI-NETs) are rare, hormone producing and proliferate slowly. Patients usually display metastases at time of diagnosis, the tumours are difficult to cure, and the disease course is unpredictable.The gene expression pattern was investigated in paper I, with emphasis on aggressive disease and tumour progression. Expression microarrays were performed on 42 tumours. Unsupervised hierarchal clustering revealed three clusters that were correlated to clinical features, and expression changes from primary tumour to metastasis. Eight novel genes, ACTG2, GREM2, REG3A, TUSC2, RUNX1, TGFBR2, TPH1 and CDH6 may be of importance for tumour progression.In paper II, expression of ACTG2 was detected in a fraction of SI-NETs, but not in normal enterochromaffin cells. Inhibition of histone methyltransferase and transfection of miR-145 induced expression and no effect was seen after DNA methylation or selective EZH2 inhibition in vitro. miR-145 expression was reduced in metastases compared to primary tumours. Overexpression of ACTG2 inhibited cell growth, and inducing ACTG2 may have therapeutic effects.TCEB3C (Elongin A3) is located on chromosome 18 and is imprinted in some tissues. In paper III a reduced protein expression was detected. The gene was epigenetically repressed by both DNA and histone methylation in a tumour tissue specific context. The expression was also induced in primary cell cultures after DNA demethylation and pyrosequencing revealed promoter region hypermethylation. Overexpression of TCEB3C inhibited cell growth by 50%, suggesting TCEB3C to be a tumour suppressor gene.In paper IV, 69 biomarkers were analysed in blood serum using multiplex proximity ligation assay. Nineteen markers displayed different levels between patients and controls. In an extended cohort, ELISA analysis showed elevated serum levels of Mindin, DcR3 and TFF3 in patients and protein expression in tumour cells. High levels of DcR3 and TFF3 were associated with poor survival, and DcR3 may be a marker for liver metastases. Mindin, DcR3, and TFF3 are potential novel diagnostic biomarkers for SI-NETs.
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| 2. |
- Rudholm Feldreich, Tobias
(author)
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Gastric acid secretion and gut peptides : mechanisms involved in inflammatory response
- 2010
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Doctoral thesis (other academic/artistic)abstract
- The regulation of gastric acid secretion is complex and involves endocrine, paracrine, and neurocrine mechanisms. Among these, the interconnecting cross-talk between different gut peptides is an important part in the control of acid secretion. The aims of this thesis were (1) to develop a new method of measuring intragastric pH for prolonged periods of time, and (2) apply developed and in-use methods using different substances and their impact on gastric acid secretion in vivo experiments on rats. (3) To study the changes in acid output and the migrating motor complex (MMC) when subjected to different substances, and (4) to further study the alterations in expression of different gut peptides in tissue samples in vitro, and the impact of inflammation in the gut. The novel Bravo model developed gave reliable recordings compared to the chronic fistula model. The pH rose during treatment with esomeprazole and the acid output in the fistula model decreased accordingly. Gut peptides ghrelin and somatostatin increased in plasma when subjected to esomeprazole treatment, while gastrin remained unchanged. Ghrelin administered in bolus doses increased the intragastric pH in accordance with previous experiments. The gut peptides somatostatin, neurotensin, and vasoactive intestinal peptide increased during pentagastrin-stimulated infusion and challenge with hydrochloric acid and polyethylene glycol both in plasma and intestinal perfusate, though the most pronounced elevation was seen in perfusate and with somatostatin. Gastrazole gave the most extensive inhibitory effect on acid secretion compared to ranitidine and esomeprazole. The CCK2-receptor antagonist YF476 inhibited acid secretion long-term and increased concentrations of ghrelin and somatostatin in plasma, but gastrin remained low. Tissue mRNA content of the peptides and their receptors were unchanged except for the ghrelin receptor. When subdued to NSAID gastrin, CCK2-receptor and iNOS increased in mRNA expression while other peptides and receptors were unchanged. Administration of NPS evoked a response in the MMC pattern with irregular spiking and prolonged cycle length of the activity fronts, and the mRNA expression of iNOS, TNF, and IL-1ß increased in the tissue. In conclusion, The Bravo model can be used as a complement to the chronic fistula model for measurements of pH. The regulation of gastric acid secretion is not only limited to the stomach, but also present in the smaller intestine where release of somatostatin seems to be most important. Different mechanisms are involved in the blockage of acid secretion when subjected to YF476, but under NSAID treatment the expression of gastrin and its receptor CCK2 increase and COX- 2 is activated which demonstrates a novel pathway for the study of gastric ulcerations. NPS, a novel neuropeptide influences the gastric motility and could have a role in inflammatory responses seen in the changes in the migrating motor complex and inflammatory markers iNOS, TNF, and IL-1ß.
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| 3. |
- Stridh, Sara, 1983-
(author)
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Regulation of Renal Hyaluronan in Water Handling : Studies in vivo and in vitro
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Hyaluronan (HA) is a negatively charged extracellular matrix (ECM) component with water-attracting properties. It is the dominating ECM component in the renal medullary interstitium, where the amount changes in relation to hydration status: it increases during hydration and decreases during dehydration. It has, therefore, been suggested that HA participates in the regulation of renal fluid handling by changing the permeability properties of the interstitial space. This thesis investigates potential mechanisms for such a role in renal fluid regulation.The results demonstrate that the high renal HA content of late nephrogenesis decreases during the completion of kidney development in the rat, which takes place in the neonatal period. The heterogenous distribution of HA is mainly established during the first three weeks after birth. On day 21, the HA content is similar to that in the adult rat. The process is dependent on normal Ang II function. It primarily involves a reduction of HA synthase 2 expression and an increase of medullary hyaluronidase 1. The cortical accumulation of HA that results from neonatal ACE inhibition can partly explain the pathological condition of the adult kidney, which causes reduced urinary concentration ability and tubulointerstitial inflammation.It is possible to reduce renomedullary HA with the HA synthesis inhibitor 4-MU, and the kidney’s ability to respond to a hydration challenge will then be suppressed, without affecting GFR. The investigation of renomedullary interstitial cells (RMIC) in culture, shows that media osmolality and hormones of central importance for body fluid homeostasis, such as angiotensin II, ADH and endothelin, affect HA turnover through their effect on the RMICs, in a manner comparable to that found in vivo during changes in hydration status. In established streptozotocin-induced diabetes, HA is regionally accumulated in the kidney, proteinuria and polyuria, reduced urine osmolality, and reduced response to ADH V2 activation will occur. As opposed to the proteinuria, the HA accumulation is not sensitive to mTOR inhibition, suggesting an alternate pathway compared to other ECM components Taken together, the data suggest that during normal physiological conditions, renomedullary interstitial HA participates in renal fluid handling by affecting the interstitial prerequisites for fluid flux across the interstitial space. This is possible due to the water-attracting and physicochemical properties of this glycosaminoglycan. During pathological conditions, such as diabetes, the elevated interstitial HA can contribute to the defective kidney function, due to the proinflammatory and water-attracting properties of HA.
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