se encontra na presença de um campo magnético, este é modificado por causa da magnetização resultante, M, do momento de dipolo molecular 97. Esta magnetização pode
ser puramente devido à interação do campo aplicado com a matéria ou pode já existir mesmo na ausência do campo externo, como ocorre nos materiais ferromagnéticos 97. Os
tecidos do corpo humano contêm 4 componentes magnéticos principais: tecido diamagnético, núcleos antiferromagnéticos de ferrihydrite da ferritina, sangue quase paramagnético e magnetite e/ou maghemite ferrimagnética. A magnetização dos materiais diamagnéticos tende a enfraquecer a suscetibilidade magnética 97. Geralmente
o efeito diamagnético nos materiais é mascarado pelo comportamento paramagnético e ferromagnético 97, no entanto em amostras teciduais com valores de massa superiores, o
comportamento diamagnético sobrepõe-se, por vezes, ao paramagnetismo das partículas ferromagnéticas presentes nos mesmos. Assim, podemos concluir que o método de SM não é adequado para a medição das propriedades magnéticas dos tecidos, à temperatura ambiente, porque é muito sensível às características diamagnéticas dos tecidos e paramagnéticas do sangue.
Pelo contrário a determinação da MRI mostrou ser uma metodologia eficaz para o estudo das estruturas magnéticas presentes nos tecidos pois não influenciada por estruturas diamagnéticas ou paramagnéticas.
À exceção dos tecidos provenientes da hipófise, todas as amostras atingiram a saturação entre os 200 e os 300 mT, característica da presença de uma fase de baixa coercividade e indicativa da presença de óxidos de ferro ferrimagnéticos. Esta saturação é consistente com estudos prévios realizados em tecidos de órgãos humano e com a presença de magnetite e/ou maghemite (γ-Fe2O3 – um produto da oxidação da magnetite com uma magnetização de saturação ligeiramente inferior) biogénicas 4,6,28,44,45,47,58.
Estes resultados sugerem que embora o comportamento paramagnético e diamagnético seja comum a todas as amostras, estruturas do tipo magnetite e hematite estão presentes em algumas amostras de tecidos colhidos.
Como todas as análises foram realizadas em cadáveres, existe a possibilidade de o material magnético ser um artefacto, formado como resultado de alterações químicas
têm valores de SM inferiores, não sendo estes fenómenos responsáveis pela presença de artefactos ferrimagnéticos.
A distribuição dos minerais ferrimagnéticos no cérebro é heterogénea 6, o que pode
dever-se à presença de estruturas mielinizadas. Serão necessários estudos histoquímicos subsequentes, a utilização de marcadores para a mielina e a consideração da orientação das fibras da substância branca relativamente ao campo magnético principal, para determinar a sua contribuição para a SM total.
A descoberta do papel de vários materiais magnéticos em muitos seres vivos, particularmente em humanos, está apenas no início. Após décadas de estudo dos biominerais magnéticos, é claro que em muitos casos eles desempenham um importante papel nos processos biológicos e podem fornecer informações importantes acerca dos mecanismos de interação entre os campos eletromagnéticos ambientais e os organismos.
O estudo não foi comprometido por danos devido à fixação química, que pode degradar as microestruturas dos tecidos e alterar consequentemente o sinal magnético 106,107.
Os níveis de magnetite obtidos são inferiores aos que foram obtidas por outros autores, o que pode dever-se a diversos fatores: as medições deste estudo foram efetuadas em amostras à temperatura ambiente e há contribuição das partículas superparamagneticas para a magnetização remanescente da amostra. Os tecidos foram recolhidos exclusivamente de cadáveres, apesar de não terem sido fixados com alguma solução, o sinal pode ser inferior em comparação de tecidos frescos, removidos por cirurgia.
Para além disto, não encontrámos diferenças significativas entre os valores obtidos para tecidos patológicos e não patológicos. Ao nível das artérias coronárias verificámos uma diminuição, devido à interferência das propriedades diamagnéticas dos tecidos. As curvas de MRI permitiram a identificação da mineralogia presente nos tecidos, a determinação das dimensões e concentrações das partículas, pelo que são um método útil, embora seja necessário, num estudo posterior, obter valores de MRI a 77 K e a 273 K, para eliminar a contribuição dia e paramagnética dos tecidos e substâncias sem interesse para as nossas determinações. A força da contribuição diamagnética, originada pela matriz orgânica do tecido, pode ser estimada pela magnetização em função da temperatura 4. A
concentração de magnetite é menor a 273 K devido ao desbloqueamento de partículas superparamagnéticas a temperaturas superiores 4.
Apesar de ser evidente que a magnetite e/ou maghemite estão presentes em órgãos humanos, para confirmar estes resultados será necessário proceder-se à extração e
observação direta destas partículas, usando a microscopia eletrónica, ou por técnicas de RM, embora mais dispendiosas.
Como a magnetite biogénica proporciona um possível mecanismo para interações de campos magnéticos fracos com o cérebro humano 57,60,108, é importante examinar a sua
5. Bibliografia
1 Evans, M. E. & Heller, F. Environmental Magnetism: Principles and
Applications of Enviromagnetics. (Academic Press, 2003).
2 Walker, M. M. et al. Structure and function of the vertebrate magnetic sense.
Nature 390, 371-376 (1997).
3 Dobson, J. Magnetic iron compounds in neurological disorders. Annals of the
New York Academy of Sciences 1012, 183-192 (2004).
4 Brem, F., Hirt, A. M., Simon, C., Wieser, H. G. & Dobson, J. Characterization of
iron compounds in tumour tissue from temporal lobe epilepsy patients using low temperature magnetic methods. Biometals : an international journal on the role
of metal ions in biology, biochemistry, and medicine 18, 191-197 (2005).
5 Mosiniewicz-Szablewska, E. et al. Electron paramagnetic resonance studies of
human liver tissues. Applied magnetic resonance 24, 429-435,
doi:10.1007/BF03166946 (2003).
6 Brem, F. et al. Magnetic iron compounds in the human brain: a comparison of
tumour and hippocampal tissue. Journal of the Royal Society, Interface / the
Royal Society 3, 833-841, doi:10.1098/rsif.2006.0133 (2006).
7 Haacke, E. M. et al. Imaging iron stores in the brain using magnetic resonance
imaging. Magnetic resonance imaging 23, 1-25, doi:10.1016/j.mri.2004.10.001 (2005).
8 Harrison, P. M. & Arosio, P. The ferritins: molecular properties, iron storage
function and cellular regulation. Biochimica et biophysica acta 1275, 161-203 (1996).
9 Schenck, J. F. & Zimmerman, E. A. High-field magnetic resonance imaging of
brain iron: birth of a biomarker? NMR in biomedicine 17, 433-445, doi:10.1002/nbm.922 (2004).
10 Brik, A. B. Magnetic biominerals localised in brain tissue: anomalous properties,
possible functional role and synthetic analogues. Ukrainian Journal of Physical
Optics 11 (2010).
11 Schweser, F., Deistung, A., Lehr, B. W. & Reichenbach, J. R. Quantitative
imaging of intrinsic magnetic tissue properties using MRI signal phase: an approach to in vivo brain iron metabolism? NeuroImage 54, 2789-2807, doi:10.1016/j.neuroimage.2010.10.070 (2011).
12 St Pierre, T., Webb, J. & Mann, S. in Biomineralization: Chemical and
Biochemical Perspectives (eds S. Mann, J. Webb, & R. J. P. Williams) (Weinheim: VCH Verlangsgesellschaft, 1989).
13 Chua-anusorn, W., Webb, J., Macey, D. J., de la Motte Hall, P. & St Pierre, T. G.
The effect of prolonged iron loading on the chemical form of iron oxide deposits in rat liver and spleen. Biochimica et biophysica acta 1454, 191-200 (1999).
14 Beard, J. L., Connor, J. R. & Jones, B. C. Iron in the brain. Nutrition reviews 51,
157-170 (1993).
15 Goodman, L. Alzheimer's disease; a clinico-pathologic analysis of twenty-three
cases with a theory on pathogenesis. The Journal of nervous and mental disease
16 Fischer, P., Gotz, M. E., Danielczyk, W., Gsell, W. & Riederer, P. Blood transferrin and ferritin in Alzheimer's disease. Life sciences 60, 2273-2278 (1997).
17 Loeffler, D. A. et al. Transferrin and iron in normal, Alzheimer's disease, and
Parkinson's disease brain regions. Journal of neurochemistry 65, 710-724 (1995).
18 Ikeda, M. Iron overload without the C282Y mutation in patients with epilepsy.
Journal of neurology, neurosurgery, and psychiatry 70, 551-553 (2001).
19 Ueda, Y. & Willmore, L. J. Sequential changes in glutamate transporter protein
levels during Fe(3+)-induced epileptogenesis. Epilepsy research 39, 201-209 (2000).
20 Ueda, Y., Willmore, L. J. & Triggs, W. J. Amygdalar injection of FeCl3 causes
spontaneous recurrent seizures. Experimental neurology 153, 123-127, doi:10.1006/exnr.1998.6869 (1998).
21 Arosio, P. & Levi, S. Ferritin, iron homeostasis, and oxidative damage. Free
radical biology & medicine 33, 457-463 (2002).
22 Kobayashi, A. K., Yamamoto, N. & Kirschvink, J. L. Studies of Inorganic
Crystals in Biological Tissue: Magnetite in Human Tumor. Journal of the Japan
Society of Powder and Powder Metallurgy 44 (1997).
23 Mykhaylyk, O., Dudchenko, N., Cherchenko, A., Rozumenko, V. & Zozulya, Y.
Dysregulation of non-heme iron metabolism in glial brain tumors. Medical
principles and practice : international journal of the Kuwait University, Health Science Centre 14, 221-229, doi:10.1159/000085739 (2005).
24 Cohen, D. Ferromagnetic contamination in the lungs and other organs of the
human body. Science 180, 745-748 (1973).
25 Chasteen, N. D. & Harrison, P. M. Mineralization in ferritin: an efficient means
of iron storage. Journal of structural biology 126, 182-194,
doi:10.1006/jsbi.1999.4118 (1999).
26 Ramanujan, R. in Biomedical Materials (ed R. Narayan) (Springer Science +
Business Media, LLC, 2009).
27 Maher, B. A. & Thompson, R. Quaternary Climates, Environments and
Magnetism. (Cambridge University Press, 1999).
28 Kirschvink, J. L., Kobayashi-Kirschvink, A. & Woodford, B. J. Magnetite
biomineralization in the human brain. Proceedings of the National Academy of
Sciences of the United States of America 89, 7683-7687 (1992).
29 Bauman, J. H. & Harris, J. W. Estimation of hepatic iron stores by vivo
measurement of magnetic susceptibility. The Journal of laboratory and clinical
medicine 70, 246-257 (1967).
30 Brittenham, G. M. et al. Magnetic-susceptibility measurement of human iron
stores. The New England journal of medicine 307, 1671-1675,
doi:10.1056/NEJM198212303072703 (1982).
31 Senftle, F. E. & Thorpe, A. Magnetic susceptibility of normal liver and
transplantable hepatoma tissue. Nature 190, 410-413 (1961).
32 Ogawa, S., Lee, T., Nayak, A. S. & Glynn, P. Oxygenation-sensitive contrast in
magnetic resonance image of rodent brain at high magnetic fields. Magnetic
Resonance in Medicine 14, 68-78, doi:10.1002/mrm.1910140108 (1990).
Hirnforschung. Experimentation cerebrale 144, 122-126, doi:10.1007/s00221- 002-1066-0 (2002).
34 Strbak, O., Kopcansky, P. & Frollo, I. Biogenic Magnetite in Humans and New
Magnetic Resonance Hazard Questions. Measurement Science Review 11, 85-91, doi:10.2478/v10048-011-0014-1 (2011).
35 Blakemore, R. Magnetotactic bacteria. Science 190, 377-379 (1975).
36 Webb, J., St Pierre, T. & Macey, D. J. in Iron biominerals (eds R. B. Frankel &
R. Blakemore) (R.P. Plenum Publishing Corp., 1990).
37 Frankel, R. B. Magnetic guidance of organisms. Annual review of biophysics
and bioengineering 13, 85-103, doi:10.1146/annurev.bb.13.060184.000505 (1984).
38 de Araujo, F. F., Pires, M. A., Frankel, R. B. & Bicudo, C. E. Magnetite and
magnetotaxis in algae. Biophysical journal 50, 375-378 (1986).
39 Lowenstam, H. A. Goethite in Radular Teeth of Recent Marine Gastropods.
Science 137, 279-280, doi:10.1126/science.137.3526.279 (1962).
40 Gould, J. L., Kirschvink, J. L., Deffeyes, K. S. & Brines, M. L. Orientation of
demagnetized bees. J. exp. Biol 86, 1-8 (1980).
41 Walcott, C., Gould, J. L. & Kirschvink, J. L. Pigeons have magnets. Science 205,
1027-1029 (1979).
42 Mann, S., Sparks, N. H., Walker, M. M. & Kirschvink, J. L. Ultrastructure,
morphology and organization of biogenic magnetite from sockeye salmon, Oncorhynchus nerka: implications for magnetoreception. The Journal of
experimental biology 140, 35-49 (1988).
43 Kirschvink, J. L., Jones, D. S. & MacFadden, B.-J. Magnetite Biomineralization
and Magnetoreception in Organisms: A New Biomagnetism. (Plenum, 1985).
44 Dobson, J. et al. in Biomagnetism: Fundamental Research and clinical
applications (eds M. Baumgarten, L. Deecke, G. Stroink, & S. J. Williamson) 16-19 (Elsevier/ISO Press, 1995).
45 Dunn, J. R. et al. Magnetic material in the human hippocampus. Brain research
bulletin 36, 149-153 (1995).
46 Sayre, L. M. et al. In situ oxidative catalysis by neurofibrillary tangles and senile
plaques in Alzheimer's disease: a central role for bound transition metals.
Journal of neurochemistry 74, 270-279 (2000).
47 Dobson, J. & Grassi, P. Magnetic properties of human hippocampal tissue--
evaluation of artefact and contamination sources. Brain research bulletin 39, 255-259 (1996).
48 Schultheiss-Grassi, P. P. & Dobson, J. Magnetic analysis of human brain tissue.
Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine 12, 67-72 (1999).
49 Hautot, D., Pankhurst, Q. A., Khan, N. & Dobson, J. Preliminary evaluation of
nanoscale biogenic magnetite in Alzheimer's disease brain tissue. Proceedings.
Biological sciences / The Royal Society 270 Suppl 1, S62-64, doi:10.1098/rsbl.2003.0012 (2003).
50 Collingwood, J. F. et al. In situ characterization and mapping of iron compounds
in Alzheimer's disease tissue. Journal of Alzheimer's disease : JAD 7, 267-272 (2005).
51 Dobson, J. Nanoscale biogenic iron oxides and neurodegenerative disease. FEBS
52 Fuller, M., Dobson, J., Wieser, H. G. & Moser, S. On the sensitivity of the human brain to magnetic fields: evocation of epileptiform activity. Brain
research bulletin 36, 155-159 (1995).
53 Schafer, F. Q., Qian, S. Y. & Buettner, G. R. Iron and free radical oxidations in
cell membranes. Cell Mol Biol (Noisy-le-grand) 46, 657-662 (2000).
54 Quintana, C. et al. Initial studies with high resolution TEM and electron energy
loss spectroscopy studies of ferritin cores extracted from brains of patients with progressive supranuclear palsy and Alzheimer disease. Cell Mol Biol (Noisy-le-
grand) 46, 807-820 (2000).
55 Grassi-Schultheiss, P. P., Heller, F. & Dobson, J. Analysis of magnetic material
in the human heart, spleen and liver. Biometals : an international journal on the
role of metal ions in biology, biochemistry, and medicine 10, 351-355 (1997).
56 Sakai, H., Wang, H., Murai, Y., Soukejima, S. & Kagamimori, S. [Study of
remanent magnetization of the human body: lung and liver tissues]. Nihon
eiseigaku zasshi. Japanese journal of hygiene 56, 523-527 (2001).
57 Dobson, J. & St Pierre, T. Application of the ferromagnetic transduction model
to D.C. and pulsed magnetic fields: effects on epileptogenic tissue and implications for cellular phone safety. Biochemical and biophysical research
communications 227, 718-723 (1996).
58 Kobayashi, A. K. & Kirschvink, J. L. in ACS Advances in Chemistry Series No.
250, Electromagnetic fields: Biological interactions and mechanisms (ed B. Martin) (Amer. Chem. Soc., 1995).
59 Ptitsyna, N. G. et al. [Electric traction magnetic fields of ultra-low frequency as
an occupational risk factor of ischemic heart disease]. Meditsina truda i
promyshlennaia ekologiia, 22-25 (1996).
60 Kirschvink, J. L. Microwave absorption by magnetite: a possible mechanism for
coupling nonthermal levels of radiation to biological systems.
Bioelectromagnetics 17, 187-194, doi:10.1002/(SICI)1521-
186X(1996)17:3<187::AID-BEM4>3.0.CO;2-# (1996).
61 Fuller, M., Wilson, C. L., Velasco, A. L., Dunn, J. R. & Zoeger, J. On the
confirmation of an effect of magnetic fields on the interictal firing rate of epileptic patients. Brain research bulletin 60, 43-52 (2003).
62 Chignell, C. F. & Sik, R. H. Effect of magnetite particles on photoinduced and
nonphotoinduced free radical processes in human erythrocytes. Photochemistry
and photobiology 68, 598-601 (1998).
63 McLean, M., Engstrom, S. & Holcomb, R. Static Magnetic Fields for the
Treatment of Pain. Epilepsy & Behavior 2, S74–S80,
doi:10.1006/ebeh.2001.0211 (2001).
64 Willmore, L. J., Hurd, R. W. & Sypert, G. W. Epileptiform activity initiated by
pial iontophoresis of ferrous and ferric chloride on rat cerebral cortex. Brain
research 152, 406-410 (1978).
65 Baranzelli, M. C. et al. Non-seminomatous ovarian germ cell tumours in
children. Eur J Cancer 36, 376-383 (2000).
66 Stadler, N., Lindner, R. A. & Davies, M. J. Direct detection and quantification of
transition metal ions in human atherosclerotic plaques: evidence for the presence of elevated levels of iron and copper. Arteriosclerosis, thrombosis, and vascular
67 Swain, J. & Gutteridge, J. M. Prooxidant iron and copper, with ferroxidase and xanthine oxidase activities in human atherosclerotic material. FEBS letters 368, 513-515 (1995).
68 Raman, S. V. et al. In vivo atherosclerotic plaque characterization using
magnetic susceptibility distinguishes symptom-producing plaques. JACC.
Cardiovascular imaging 1, 49-57, doi:10.1016/j.jcmg.2007.09.002 (2008).
69 Gehr, P. Respiratory tract structure and function. Journal of toxicology and
environmental health 13, 235-249, doi:10.1080/15287398409530496 (1984).
70 Seeley, R., Stephens, T. & Tate, P. Anatomia & Fisiologia. 6 edn, (Lusociência,
2003).
71 Moller, W., Barth, W., Kohlhaufl, M., Haussinger, K. & Kreyling, W. G. Motion
and twisting of magnetic particles ingested by alveolar macrophages in the human lung: effect of smoking and disease. Biomagnetic research and
technology 4, 4, doi:10.1186/1477-044X-4-4 (2006).
72 Mutti, A. & Corradi, M. Recent developments in human biomonitoring: non-
invasive assessment of target tissue dose and effects of pneumotoxic metals. La
Medicina del lavoro 97, 199-206 (2006).
73 Posfai, M., Buseck, P. R., Bazylinski, D. A. & Frankel, R. B. Reaction sequence
of iron sulfide minerals in bacteria and their use as biomarkers. Science 280, 880-883 (1998).
74 Quintana, C., Cowley, J. M. & Marhic, C. Electron nanodiffraction and high-
resolution electron microscopy studies of the structure and composition of physiological and pathological ferritin. Journal of structural biology 147, 166- 178, doi:10.1016/j.jsb.2004.03.001 (2004).
75 Bartzokis, G., Tishler, T. A., Shin, I. S., Lu, P. H. & Cummings, J. L. Brain
ferritin iron as a risk factor for age at onset in neurodegenerative diseases.
Annals of the New York Academy of Sciences 1012, 224-236 (2004).
76 Schweser, F., Sommer, K., Deistung, A. & Reichenbach, J. R. Quantitative
susceptibility mapping for investigating subtle susceptibility variations in the
human brain. NeuroImage 62, 2083-2100,
doi:10.1016/j.neuroimage.2012.05.067 (2012).
77 Li, W., Wu, B., Avram, A. V. & Liu, C. Magnetic susceptibility anisotropy of
human brain in vivo and its molecular underpinnings. NeuroImage 59, 2088- 2097, doi:10.1016/j.neuroimage.2011.10.038 (2012).
78 Li, X. et al. Mapping magnetic susceptibility anisotropies of white matter in
vivo in the human brain at 7 T. NeuroImage 62, 314-330,
doi:10.1016/j.neuroimage.2012.04.042 (2012).
79 Wharton, S. & Bowtell, R. Whole-brain susceptibility mapping at high field: a
comparison of multiple- and single-orientation methods. NeuroImage 53, 515- 525, doi:10.1016/j.neuroimage.2010.06.070 (2010).
80 Bilgic, B., Pfefferbaum, A., Rohlfing, T., Sullivan, E. V. & Adalsteinsson, E.
MRI estimates of brain iron concentration in normal aging using quantitative
susceptibility mapping. NeuroImage 59, 2625-2635,
doi:10.1016/j.neuroimage.2011.08.077 (2012).
81 Zivadinov, R. et al. Abnormal subcortical deep-gray matter susceptibility-
weighted imaging filtered phase measurements in patients with multiple
sclerosis: a case-control study. NeuroImage 59, 331-339,
82 Schweser, F., Deistung, A., Lehr, B. W. & Reichenbach, J. R. Differentiation between diamagnetic and paramagnetic cerebral lesions based on magnetic susceptibility mapping. Medical physics 37, 5165-5178 (2010).
83 Pitt, D. et al. Imaging cortical lesions in multiple sclerosis with ultra-high-field
magnetic resonance imaging. Archives of neurology 67, 812-818,
doi:10.1001/archneurol.2010.148 (2010).
84 Fukunaga, M. et al. Layer-specific variation of iron content in cerebral cortex as
a source of MRI contrast. Proceedings of the National Academy of Sciences of
the United States of America 107, 3834-3839, doi:10.1073/pnas.0911177107 (2010).
85 Duyn, J. H. et al. High-field MRI of brain cortical substructure based on signal
phase. Proceedings of the National Academy of Sciences of the United States of
America 104, 11796-11801, doi:10.1073/pnas.0610821104 (2007).
86 He, X. & Yablonskiy, D. A. Biophysical mechanisms of phase contrast in
gradient echo MRI. Proceedings of the National Academy of Sciences of the
United States of America 106, 13558-13563, doi:10.1073/pnas.0904899106 (2009).
87 Lee, J. et al. Sensitivity of MRI resonance frequency to the orientation of brain
tissue microstructure. Proceedings of the National Academy of Sciences of the
United States of America 107, 5130-5135, doi:10.1073/pnas.0910222107 (2010).
88 Li, W., Wu, B. & Liu, C. Quantitative susceptibility mapping of human brain
reflects spatial variation in tissue composition. NeuroImage 55, 1645-1656, doi:10.1016/j.neuroimage.2010.11.088 (2011).
89 Liu, C. Susceptibility tensor imaging. Magnetic resonance in medicine : official
journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 63, 1471-1477, doi:10.1002/mrm.22482 (2010).
90 Gerlach, M., Ben-Shachar, D., Riederer, P. & Youdim, M. B. Altered brain
metabolism of iron as a cause of neurodegenerative diseases? Journal of
neurochemistry 63, 793-807 (1994).
91 Ke, Y. & Ming Qian, Z. Iron misregulation in the brain: a primary cause of
neurodegenerative disorders. Lancet neurology 2, 246-253 (2003).
92 Weaver, J. C. Understanding conditions for which biological effects of
nonionizing electromagnetic fields can be expected. Bioelectrochemistry 56, 207-209 (2002).
93 Kirschvink, J. L. Rock magnetism linked to human brain magnetite. Transaction
American Geophysical Union 75, 178-179, doi:10.1029/94EO00859 (1994).
94 Warnke, U. Bees, Birds and Mankind: Destroying Nature by 'Electrosmog'. A
Brochure Series by the Competence Initiative for the Protection of Humanity, Environment and Democracy (2007).
95 Sant'Ovaia, H. L., M. & Gomes, C. Particle pollution - An environmental
magnetism study using biocollectors located in northern Portugal. Atmospheric
Environment 61, 340-349 (2012).
96 Moreno, E., Sagnotti, L., Dinarès-Turell, J., Winkler, A. & Cascella, A.
Biomonitoring of traffic air pollution in Rome using magnetic properties of tree leaves. Atmospheric Environment 37, 2967-2977 (2003).
97 Carneiro, A. A. et al. Liver iron concentration evaluated by two magnetic
Medicine / Society of Magnetic Resonance in Medicine 54, 122-128, doi:10.1002/mrm.20510 (2005).
98 Sadrzadeh, S. M. & Saffari, Y. Iron and brain disorders. American journal of
clinical pathology 121 Suppl, S64-70 (2004).
99 Beard, J. Iron deficiency alters brain development and functioning. The Journal
of nutrition 133, 1468S-1472S (2003).
100 Langkammer, C. et al. Quantitative susceptibility mapping (QSM) as a means to
measure brain iron? A post mortem validation study. NeuroImage 62, 1593- 1599, doi:10.1016/j.neuroimage.2012.05.049 (2012).
101 Sandgren, P. T., R. Ch. Mineral magnetic characteristics of podzolic soils
developed on sand dunes in the Lake Gosciaz catchment, central Poland, 297- 313 (1990).
102 Burdo, J. R. & Connor, J. R. Brain iron uptake and homeostatic mechanisms: an
overview. Biometals : an international journal on the role of metal ions in
biology, biochemistry, and medicine 16, 63-75 (2003).
103 Langkammer, C. et al. Susceptibility induced gray-white matter MRI contrast in
the human brain. NeuroImage 59, 1413-1419,
doi:10.1016/j.neuroimage.2011.08.045 (2012).
104 Denk, C., Hernandez Torres, E., MacKay, A. & Rauscher, A. The influence of
white matter fibre orientation on MR signal phase and decay. NMR in
biomedicine 24, 246-252, doi:10.1002/nbm.1581 (2011).
105 Connor, J. R. & Menzies, S. L. Relationship of iron to oligodendrocytes and
myelination. Glia 17, 83-93, doi:10.1002/(SICI)1098-
1136(199606)17:2<83::AID-GLIA1>3.0.CO;2-7 (1996).
106 Dawe, R. J., Bennett, D. A., Schneider, J. A., Vasireddi, S. K. & Arfanakis, K.
Postmortem MRI of human brain hemispheres: T2 relaxation times during formaldehyde fixation. Magnetic resonance in medicine : official journal of the
Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 61, 810-818, doi:10.1002/mrm.21909 (2009).
107 Schmierer, K. et al. Quantitative magnetic resonance of postmortem multiple
sclerosis brain before and after fixation. Magnetic resonance in medicine :
official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 59, 268-277, doi:10.1002/mrm.21487 (2008).
108 Kirschvink, J. L., Kobayashi-Kirschvink, A., Diaz-Ricci, J. C. & Kirschvink, S.
J. Magnetite in human tissues: a mechanism for the biological effects of weak ELF magnetic fields. Bioelectromagnetics Suppl 1, 101-113 (1992).
Anexos
A. Material
Figura 11: Porta-amostras. Dimensões: 2 cm x 2 cm x 2 cm.
Fonte: http://www.ascscientific.com/boxes.html
Figura 12: Exsicador.
´
Figura 14: Balança analítica Mettler At 240.
Figura 15: Magnetómetro Molspin Minispin
Fonte: http://faculty.kfupm.edu.sa/ES/akwahab/RML.htm
Figura 16: Magnetizador de pulso