Dramatic Effect of Magnetite Particles on the Dynamics of Photogenerated Free Radicals

Scaiano, J. C.; Monahan, Sarah; Renaud, Jocelyn

doi:10.1111/j.1751-1097.1997.tb01921.x

Cited by 23 publications

(15 citation statements)

References 24 publications

(9 reference statements)

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“…It has also been pointed out that trace amounts of magnetite may be ubiquitous and that a single 100-nm magnetite crystal exposed to a 60 Hz, 0.1 mT magnetic field could absorb sufficient energy to supercede thermal background noise several fold (Kobayashi et al 1995). Magnetite particles can have dramatic effects on the dynamics of photogenerated free radicals (Scaiano et al 1997). Particularly in the context of the radical-pair mechanism (see below) it is thus pertinent to reckon with the modulating effect of magnetites if present.…”

Section: Ferrimagnetismmentioning

confidence: 98%

Magnetoreception in plants

2005

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This article reviews phenomena of magnetoreception in plants and provides a survey of the relevant literature over the past 80 years. Plants react in a multitude of ways to geomagnetic fields-strong continuous fields as well as alternating magnetic fields. In the past, physiological investigations were pursued in a somewhat unsystematic manner and no biological advantage of any magnetoresponse is immediately obvious. As a result, most studies remain largely on a phenomenological level and are in general characterised by a lack of mechanistic insight, despite the fact that physics provides several theories that serve as paradigms for magnetoreception. Beside ferrimagnetism, which is well proved for bacterial magnetotaxis and for some cases of animal navigation, two further mechanisms for magnetoreception are currently receiving major attention: (1) the "radical-pair mechanism" consisting of the modulation of singlet-triplet interconversion rates of a radical pair by weak magnetic fields, and (2) the "ion cyclotron resonance" mechanism. The latter mechanism centres around the fact that ions should circulate in a plane perpendicular to an external magnetic field with their Lamor frequencies, which can interfere with an alternating electromagnetic field. Both mechanisms provide a theoretical framework for future model-guided investigations in the realm of plant magnetoreception.

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Section: Ferrimagnetismmentioning

confidence: 98%

Magnetoreception in plants

2005

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“…However, in a recent SQUID magnetometry study, Hautot et al [67] reported elevated levels of biogenic magnetite in female AD subjects compared to both male and female controls. The significance of these findings is that magnetite provides a potential source of ferrous iron, which is available for oxidation and participation in Fenton chemistry (the oxidation product of magnetite, maghemite-cFe 2 O 3 , has also been found in AD tissue) and may potentiate free radical formation in AD tissue via triplet state stabilization [68][69][70][71].…”

Section: Iron-containing Compounds Related To Alzheimer Diseasementioning

confidence: 98%

Iron: The Redox-active Center of Oxidative Stress in Alzheimer Disease

et al. 2007

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Although iron is essential in maintaining the function of the central nervous system, it is a potent source of reactive oxygen species. Excessive iron accumulation occurs in many neurodegenerative diseases including Alzheimer disease (AD), Parkinson's disease, and Creutzfeldt-Jakob disease, raising the possibility that oxidative stress is intimately involved in the neurodegenerative process. AD in particular is associated with accumulation of numerous markers of oxidative stress; moreover, oxidative stress has been shown to precede hallmark neuropathological lesions early in the disease process, and such lesions, once present, further accumulate iron, among other markers of oxidative stress. In this review, we discuss the role of iron in the progression of AD.

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“…Magnetite is a magnetic (ferrimagnetic) iron oxide with alternating lattices of Fe 2 1 and Fe 3 1 ions, which is capable of producing free radicals via the Fenton reaction or via triplet state stabilization (Kirschvink 1992;Scaiano et al 1997;Chignell & Sik 1998). Recent experiments have also demonstrated that iron-oxygen complexes may be even more effective catalysts for free-radical damage in brain tissue than the Fenton reaction (Schafer et al 2000), so the potential deleterious effect of magnetite is possibly even more significant.…”

Section: Introductionmentioning

confidence: 95%

Preliminary evaluation of nanoscale biogenic magnetite in Alzheimer's disease brain tissue

Hautot

Pankhurst²,

Khan³

et al. 2003

Proc. R. Soc. Lond. B

125

123

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Elevated iron levels are associated with many types of neurodegenerative disease, such as Alzheimer's, Parkinson's and Huntington's diseases. However, these elevated iron levels do not necessarily correlate with elevated levels of the iron storage or transport proteins, ferritin and transferrin. As such, little is known about the form of this excess iron. It has recently been proposed that some of the excess iron in neurodegenerative tissue may be in the form of the magnetic iron oxide magnetite (Fe(3)O(4)). We demonstrate, for the first time to our knowledge, using highly sensitive superconducting quantum interference device (SQUID) magnetometry, that the concentrations of magnetite are found to be significantly higher in three samples of Alzheimer's disease tissue than in three age- and sex-matched controls. These results have implications, not only for disease progression, but also for possible early diagnosis.

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Dramatic Effect of Magnetite Particles on the Dynamics of Photogenerated Free Radicals

Cited by 23 publications

References 24 publications

Magnetoreception in plants

Magnetoreception in plants

Iron: The Redox-active Center of Oxidative Stress in Alzheimer Disease

Preliminary evaluation of nanoscale biogenic magnetite in Alzheimer's disease brain tissue

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