Showing papers by "Jeff W.M. Bulte published in 1998"
TL;DR: These studies provide evidence that, contrary to most earlier reports, the ferritin core is antiferromagnetic even at body temperature and possesses a superparamagnetic (SPM) moment due to incomplete cancellation of antiparallel sublattices, as predicted by Néel's theory.
Abstract: By combining nuclear magnetic relaxometry on 39 ferritin samples with different iron loading with magnetometry, results were obtained that suggest a new interpretation of the core structure and magnetic properties of ferritin. These studies provide evidence that, contrary to most earlier reports, the ferritin core is antiferromagnetic (AFM) even at body temperature and possesses a superparamagnetic (SPM) moment due to incomplete cancellation of antiparallel sublattices, as predicted by Neel's theory. This moment also provides a likely explanation for the anomalous T2 shortening in ferritin solution. However, the number of SPM moments derived from this model is less than the number of ferritin molecules determined chemically, and a similar discrepancy was found by retrospectively fitting previously published magnetometry data. In other words, only a fraction of the ferritin molecules seem to be SPM. The studies also provide evidence for paramagnetic (PM) Curie-Weiss iron ions at the core surface, where the local Neel temperature is lower; these ions are apparently responsible for the weaker T1 shortening. In fact, the conversion of uncompensated AFM lattice ions to PM ions could explain the small number of SPM particles. The apparent Curie Law behavior of ferritin thus appears to be a coincidental result of different temperature dependences of the PM and SPM components.
136 citations
TL;DR: MION‐46L enhanced MRI may be used to provide a unique sensitivity in EAE lesion detection and correlate imaging to histopathology, and eventually assist in preclinical screening of new experimental therapies directed at patients with multiple sclerosis (MS).
Abstract: MION-46L, a superparamagnetic iron oxide contrast agent, was investigated for its ability to increase the sensitivity of in vivo 3D MRI in the detection of brain lesions in a chronic experimental allergic encephalomyelitis (crEAE) mouse model. Lesion conspicuity on postcontrast 3D MRI was dramatically enhanced as compared to precontrast images corresponding to areas of inflammatory and demyelinating lesions. MION-46L could be detected on Prussian blue iron stain in the vascular endothelium, the perivascular space, and in macrophages within perivascular cuffs and areas of inflammation and demyelination. By taking advantage of the MION-46L induced macroscopic susceptibility effect, acute early lesions measuring only 100 microm in diameter could be detected. MION-46L enhanced MRI may be used to 1) provide a unique sensitivity in EAE lesion detection and correlate imaging to histopathology; 2) help to understand EAE lesion development and its underlying pathophysiology; and 3) eventually assist in preclinical screening of new experimental therapies directed at patients with multiple sclerosis (MS).
79 citations
TL;DR: The large temperature dependence suggests that the dominant mechanism of relaxation is the contact interaction effect, with the proton residence time as the primary time constant, and this largely unexplored relaxation mechanism has the potential to create a new class of T2-selective contrast agents.
Abstract: RATIONALE AND OBJECTIVES.The authors have investigated dysprosium [Dy]-DOTA-PAMAM, generation 5 (G=5) dendrimers as a possible new class of macromolecular T2 contrast agents. The use of DOTA provides a metal complex with greater stability than can be achieved using DTPA as ligand, an important facto
47 citations
33 citations
TL;DR: Twenty ferritin samples were prepared at pH 6.5 with average loadings of 0-89 Fe atoms per molecule and residual ionic relaxivity in this region is consistent with about three solitary Fe3+ ions remaining on the protein shell, indicating that spin cancellation is not complete.
30 citations