Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Funk, D.
Establishment of a workflow for high resolution visualization of iron deposits in the human brain by analytical electron microscopy
Humanmedizin; [ Diplomarbeit ] Graz Medical University; 2018. pp. 137
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Leitinger Gerd
- Ropele Stefan
- Altmetrics:
- Abstract:
- BACKGROUND: Iron is an essential trace element in the mammalian body and is required for the functioning of living cells. However, excess iron may lead to several distinct disorders, and –especially iron overload in the brain – may cause neurodegeneration by oxidative stress reactions. Several neurological diseases, including Alzheimer’s Disease, Parkinson’s Disease and Multiple Sclerosis were proposed to be associated with elevated brain iron accumulation. To date, little is known about cells and the underlying subcellular structures involved in brain iron accumulation at advancing age. A forthcoming research study will elaborate the role of iron accumulation using electron microscopy methods in correlation with MRI and mass spectrometry. OBJECTIVE: Post-mortem brain samples of aged patients not suffering from neurological diseases were obtained for the upcoming, multidisciplinary study. This diploma thesis is a feasibility study and focuses on the electron microscopy methods to be used, with the intention of establishing a workflow in terms of image acquisition, data management and statistical evaluation. METHODS: For high resolution visualization of potential iron content, a combination of transmission electron microscopy methods were used: Energy filtered transmission electron microscopy (EFTEM) images were acquired for elemental distribution maps of cells and structures, and energy dispersive X-ray (EDX) was used for spectra analysis of transition metal content in the brain. A database (DATEM) for the overview of the images was set-up and a sample image analysis, including statistical evaluation, performed. CONCLUSION: EFTEM is suitable for detection of iron particles in biological samples. However, if osmium-tetroxide is utilized as a fixation chemical, the iron L peak should be used to avoid overlaps. DATEM as a data management tool offers a flexible and adaptable overview of acquired images for processing. In the sample images, most putative iron was found in lipofuscin granules and their underlying lipid droplets, as well as in the myelin sheaths and oligodendrocytes. This, however, might be because the iron M peak was used for the sample image acquisition, which was found to overlap with the osmium peak.