Coming dissertations at MedFak
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Physiological Studies of Native and Stem Cell-Derived Islets
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-520967
In type 1 and type 2 diabetes, the β-cells of the islets of Langerhans are either destroyed by the immune system or stressed due to peripheral insulin resistance. To improve the life of patients with these diseases, new treatments are needed. This thesis examined the role of irisin and cocaine and amphetamine regulated transcript (CART) in islets of Langerhans and their potential pharmaceutical role in type 2 diabetes. Furthermore, β-cell replacement with stem cell-derived islets of Langerhans (SC-islets) for type 1 diabetes was evaluated for optimal implantation site.
In paper I, the physiological role of CART in rat islets was examined. CART was shown to specifically lower islet blood flow, which could be a protective effect in type 2 diabetes. No effect from CART on glucose tolerance or insulin release was seen in rat islets, which highlights species differences.
In paper II, the expression of irisin and its effect on hormone secretion and pancreatic blood flow was examined. Irisin was expressed in human islets and was secreted glucose dependently. It also lowered islet blood flow but did not affect glucose-stimulated insulin secretion in isolated human or rat islets. Thus, local secretion of irisin could serve as a protective function by lowering islet blood flow in a high glucose state.
In paper III, the expression of irisin in SC-islets and its potential beneficial effects in transplantation was examined. SC-islets were found to express higher levels of irisin than human islets. Irisin treatment had no effects on viability and proliferation in SC-islets, in contrast to previous studies in other species. Thus, irisin signaling likely differs between SC-islets and murine and native human islets.
In paper IV, SC-islets were transplanted to multiple sites in mice to find the optimal implantation site in terms of graft maturity, function and composition. The liver proved to be the most favorable site due to its higher expression of islet maturity genes and a higher β-cell function and fraction. This poses a dilemma, as the liver site is the most challenging to biopsy and monitor for safety.
In summary, this thesis uncovered new physiological functions of irisin and CART, potentially offering insights relevant to the treatment of type 2 diabetes. Meanwhile, the role of irisin in transplantation of SC-islets seems limited.
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AL amyloidosis : Study of epidemiology, diagnosis and treatment with emphasis on heart involvement
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-521524
AL (immunoglobulin light chain) amyloidosis is often associated with delayed diagnosis and thereby high early mortality that is not overcome by contemporary treatment. There is a need for diagnostic methods promoting earlier diagnosis, especially in patients with cardiac involvement. Progress has been made in the treatment of AL amyloidosis and prolonged survival has been reported from specialized referral centers. However, population-based reports are scarce regarding epidemiology as well as treatment outcomes. Aims of this thesis were to increase the knowledge of the epidemiology of AL amyloidosis, investigate new imaging methods for early diagnosis and prognostication in cardiac amyloidosis (CA), and evaluate treatment options with focus on patients with cardiac involvement.
In paper I we presented real-world long-term results of treatment with high dose chemotherapy for AL amyloidosis in Sweden. We could conclude that long overall survival (median 8.2 years, 95% CI 5.1-11.2) was reached with high dose chemotherapy, but with inferior outcomes in patients with cardiac involvement. Treatment related mortality was comparable to that reported from larger centers during this period and was decreasing from 23.8% to 7.8% during the studied time period.
In paper II we studied the accuracy of PET with the amyloid binding tracer 11C-PIB for the diagnosis of CA. 11C-PIB PET showed high accuracy in detecting CA, and affinity was higher for AL compared to transthyretin amyloidosis. We concluded that 11C-PIB PET can be a useful method to rule in or out amyloidosis in patients with unexplained diastolic heart failure. Our results also indicated that 11C-PIB PET can detect CA at an earlier stage than echocardiography and might be a useful tool for early diagnosis.
In paper III we studied the prognostic value of cardiac function parameters from 11C-acetate PET in CA. We found that reduced myocardial external efficiency was associated with inferior survival in CA patients. However, the strongest prognostic parameter was lowered ratio of forward stroke volume and left ventricular mass, which was the only independently prognostic parameter in multivariable analysis.
Paper IV was a population-based epidemiological study in which we could determine the standardized incidence of systemic AL amyloidosis to 12.0 (95% CI 9.3-14.7) per million person-years for Uppsala County, without significant change during the period 2000-2020. The 5-year limited duration prevalence increased numerically, but without statistical significance. Prolonged overall survival was observed over time, and there was also a decrease in early mortality, indicating earlier diagnosis of especially patients with cardiac involvement.
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Inner ear proteomics and barriers : Clinical and experimental findings
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-519132
Hearing is important in many aspects of life, including communication, assessing one’s surroundings, entertainment and social interaction. Hearing loss is common and according to the Global Burden of Disease Study, 5% of the global population require hearing rehabilitation (1). Pharmacological treatment options are limited, so understanding cellular mechanisms in the damaged inner ear is crucial for developing novel therapies.
In this thesis, the human inner ear proteome in patients with sporadic vestibular schwannoma (VS) and its association with hearing loss were investigated. Ototoxic effects induced by furosemide were also examined, focusing on inner ear barrier function, furosemide sensitive Na-K-Cl co-transporter 1 (NKCC1), Fetuin-A, linked to tumour-associated hearing loss, and Pigment epithelium-derived factor (PEDF), potentially important for blood-endolymph barrier integrity.
Translabyrinthine surgery on 35 patients, 32 with VS and three with meningioma, provided samples from perilymph, endolymph, endolymphatic sac tissue, VS biopsies and cerebrospinal fluid (CSF) for proteome analysis. Effects of furosemide on the inner ear barriers were studied in mice using 9.4Tesla MRI, and in guinea pigs using immunohistochemistry and mRNA in situ hybridisation focusing on NKCC1, Fetuin-A, and PEDF.
Proteomic analysis revealed consistent sets of proteins in perilymph (91/315) and endolymph (545/1211). The proteomes of perilymph and CSF exhibited specific differences, with proteins unique to each fluid, thereby emphasizing the distinct origin of perilymph separate from CSF. Fetuin-A was inversely related to tumour-associated hearing loss, while patients with severe to profound hearing loss exhibited upregulation of complement factor H-related protein 2 (CFHR2).
Furosemide compromised the blood-endolymph barrier, allowing gadolinium contrast into scala media. It affected NKCC1 of type II fibrocytes coinciding with the onset of hearing loss following high-dose furosemide, suggesting early disruption in potassium ion recirculation. Fetuin-A and PEDF were identified in the cochlea at protein and mRNA level. Their staining intensity increased in various cochlear subsites 120 minutes after furosemide administration, indicating their involvement in the cochlear response to the effects of furosemide.
In summary, this thesis uncovered significant inter-individual variability in both the perilymph and endolymph proteome, alongside a consistent subset of proteins. Further, associations between hearing loss and proteome changes suggest inflammation as a potential mechanism for hearing degradation caused by vestibular schwannomas. Experimentally, impact of furosemide on blood-inner ear barriers were visualised in vivo and type II fibrocytes were identified as potential initial targets for NKCC1 blockade. Fetuin-A and PEDF were confirmed in several cell types in the cochlea and may increase in response to very high furosemide doses.