HR: 0800h
AN: GP41A-0858 [Abstracts]
TI: Comparison of the Iron Mineralogy of Tumor and Hippocampal Tissue From the Human Brain
AU: * Brem, F
EM: brem@mag.ig.erdw.ethz.ch
AF: Institute of Geophysics, ETH Hoenggerberg, Zurich, 8093
Switzerland
AU: Hirt, A M
EM: hirt@mag.ig.erdw.ethz.ch
AF: Institute of Geophysics, ETH Hoenggerberg, Zurich, 8093
Switzerland
AU: Frei, K
GP41A-0858
AF: Neurosurgical Research Laboratory, University Hospital Zurich, Zurich, 8091
Switzerland
AU: Yonekawa, Y
GP41A-0858
AF: Institute for Science and Technology in Medicine, Keele University, Stoke-on-Trent, ST4 7Q
United Kingdom
AU: Wieser, H
EM: j.p.dobson@bemp.keele.ac.uk
AF: Department of Neurosurgery, University Hospital Zurich, Zurich, 8091
Switzerland
AU: Dobson, J
GP41A-0858
AF: Neurology/EEG, University Hospital Zurich, Zurich, 8091
Switzerland
AB:
Since magnetite (Fe3O4) has been discovered in the human brain in 1992, its origin and its formation are still topics of
intense research. These questions are of even greater significance, as it has been shown that excess iron accumulation can be
associated with neurological and neurodegenerative diseases. Magnetite in the brain provides a source of ferric iron which
can lead to oxidative cell damage via the Fenton reaction. Though the source of biogenic magnetite in the brain is still
unknown, one suggestion is that the iron-storage protein ferritin could be a precursor for magnetite in the brain. A
combination of several magnetic methods has been used to characterize trace amounts of iron compounds in human brain tissue.
In this study, the magnetic properties of 8 hippocampi and 8 tumor tissues (meningiomas) are analyzed and compared by using
three different magnetic methods.
Isothermal remanent magnetization (IRM) acquisition at 300 K and 77 K reveals both diagnostic signatures of
magnetite/maghemite and information about its concentration in the samples. For meningiomas, the average saturation
magnetization is significantly higher than for the hippocampal tissue. The average of the coercivity of remanence is similar
for both types of tissue, indicating that the magnetic component in meningiomas and hippocampi is most likely identical.
Induced DC magnetization was measured between 5 K and 300 K after zero field cooling and field cooling in a 500 Oe field and
indicates the presence of a blocked magnetic component at low temperature. The ferritin component has an average blocking
temperature of around 11 K in both the hippocampi and tumor tissue. Hysteresis measurements at 5 K were made to characterize
the coercivity and remanence of ferritin below its blocking temperature.
DE: 0419 Biomineralization
DE: 1505 Biogenic magnetic minerals
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005