151 research outputs found
Biologically significant iron(III) oxyhydroxy polymers: Mössbauer spectroscopic study of ferritin and hemosiderin in pancreas tissue of β-thalassemia/hemoglobin E disease
No full textMössbauer spectra of pancreas tissue from β-thalassemia/hemoglobin E patients as well as purified ferritin and crude hemosiderin isolated from this tissue were recorded. Mössbauer spectroscopy of the ferritin showed that it contains iron cores based on the ferrihydrite (5Fe2O3·9H2O) structure consistent with previously reported electron diffraction data [T.G. St. Pierre, K.C. Tran, J. Webb, D.J. Macey, B.R. Heywood, N.H. Sparks, V.J. Wade, S. Mann and P. Pootrakul, Biol. Metals, 4 (1991) 162]. Cores in the crude hemosiderin are mainly of the ferrihydrite type but a significant amount have a defect geothite (α-FeOOH) structure. These data are interpreted in terms of the long-term deposition of iron in the pancreas in this iron overload pathology
Biominerals - source and inspiration for novel advanced materials
No full textBiomineralization seems an odd sort of word. How can you combine biology and minerals? However, a quick look around brings to light many familiar objects that are examples of biominerals. Most dramatic are the coral reefs and sea shells of the marine environment (calcium carbonate) and human bone and teeth (calcium hydroxyapatite) but there are many other examples. In the past 10 years, an increasing number of biominerals has been reported (Table 1). Interest in the biological and chemical processes that lead to biomineralization, howeyer, has only developed rather recently. Early observations were made by paleontologists who were interested in the preservation, through geological time, of the hard parts of organisms such as shells and skeletons but only in 1989 did the field really come of age with the almost simultaneous publication of three monographs covering current knowledge of the biological, biochemical, chemical and taxonomic aspects of biomineralization (Mann et al. 1989; Lowenstam & Weiner 1989; Simkiss & Wilbur 1989)
Multicenter validation of spin-density projection-assisted R2-MRI for the noninvasive measurement of liver iron concentration
No full textPurpose: Magnetic resonance imaging (MRI)-based techniques for assessing liver iron concentration (LIC) have been limited by single scanner calibration against biopsy. Here, the calibration of spin-density projection-assisted (SDPA) R2-MRI (FerriScan®) in iron-overloaded β-thalassemia patients treated with the iron chelator, deferasirox, for 12 months is validated. Methods: SDPA R2-MRI measurements and percutaneous needle liver biopsy samples were obtained from a subgroup of patients (n=233) from the ESCALATOR trial. Five different makes and models of scanner were used in the study. Results LIC, derived from mean of MRI- and biopsy-derived values, ranged from 0.7 to 50.1 mg Fe-g dry weight. Mean fractional differences between SDPA R2-MRI- and biopsy-measured LIC were not significantly different from zero. They were also not significantly different from zero when categorized for each of the Ishak stages of fibrosis and grades of necroinflammation, for subjects aged 3 to 8 versus ≥8 years, or for each scanner model. Upper and lower 95percent limits of agreement between SDPA R2-MRI and biopsy LIC measurements were 74 and -71percent. Conclusion: The calibration curve appears independent of scanner type, patient age, stage of liver fibrosis, grade of necroinflammation, and use of deferasirox chelation therapy, confirming the clinical usefulness of SDPA R2-MRI for monitoring iron overload. © 2013 Wiley Periodicals, Inc.Anderson LJ, 2001, EUR HEART J, V22, P2171, DOI 10.1053-euhj.2001.2822; ANGELUCCI E, 1995, BRIT J HAEMATOL, V89, P757; Angelucci E, 2000, NEW ENGL J MED, V343, P327, DOI 10.1056-NEJM200008033430503; Bland JM, 1999, STAT METHODS MED RES, V8, P135, DOI 10.1191-096228099673819272; Bonkovsky HL, 1999, RADIOLOGY, V212, P227; Brittenham GM, 2001, SEMIN HEMATOL, V38, P37, DOI 10.1053-shem.2001.20143; BRITTENHAM GM, 1982, NEW ENGL J MED, V307, P1671, DOI 10.1056-NEJM198212303072703; BRITTENHAM GM, 1994, NEW ENGL J MED, V331, P567, DOI 10.1056-NEJM199409013310902; Christoforidis A, 2009, EUR J HAEMATOL, V82, P388, DOI 10.1111-j.1600-0609.2009.01223.x; Clark PR, 2003, MAGNET RESON MED, V49, P572, DOI 10.1002-mrm.10378; Emond MJ, 1999, CLIN CHEM, V45, P340; Fischer R, 2003, BRIT J HAEMATOL, V121, P938, DOI 10.1046-j.1365-2141.2003.04297.x; Fischer R, 1999, AM J HEMATOL, V60, P289, DOI 10.1002-(SICI)1096-8652(199904)60:4289::AID-AJH73.0.CO;2-W; Gandon Y, 2004, LANCET, V363, P357, DOI 10.1016-S0140-6736(04)15436-6; Garbowski MW, 2009, BLOOD, V114, P2004; Hankins JS, 2009, BLOOD, V113, P4853, DOI 10.1182-blood-2008-12-191643; Hershko C, 1998, ANN NY ACAD SCI, V850, P191, DOI 10.1111-j.1749-6632.1998.tb10475.x; ISHAK K, 1995, J HEPATOL, V22, P696, DOI 10.1016-0168-8278(95)80226-6; KREEFTENBERG HG, 1984, CLIN CHIM ACTA, V144, P255, DOI 10.1016-0009-8981(84)90061-5; NIELSEN P, 1995, BRIT J HAEMATOL, V91, P827, DOI 10.1111-j.1365-2141.1995.tb05396.x; Nielsen P., 2000, Transfusion Science, V23, P257, DOI 10.1016-S0955-3886(00)00101-6; Olivieri NF, 1997, BLOOD, V89, P739; Pavitt HL, 2011, MAGN RESON MED, V65, P1346, DOI 10.1002-mrm.22712; Sirlin CB, 2010, MAGN RESON IMAGING C, V18, P359, DOI 10.1016-j.mric.2010.08.014; Soriano-Cubells MJ, 1984, ATOM SPECTROSC, V5, P217; St Pierre TG, 2005, BLOOD, V105, P855, DOI 10.1182-blood-2004-01-0177; St Pierre TG, 2004, NMR BIOMED, V17, P446, DOI 10.1002-nbm.905; Taher A, 2011, EUR J HAEMATOL, V87, P355, DOI 10.1111-j.1600-0609.2011.01662.x; Taher A, 2009, EUR J HAEMATOL, V82, P458, DOI 10.1111-j.1600-0609.2009.01228.x; Villeneuve JP, 1996, J HEPATOL, V25, P172, DOI 10.1016-S0168-8278(96)80070-5; Wood JC, 2008, HEMOGLOBIN, V32, P85, DOI 10.1080-03630260701699912; Wood JC, 2005, BLOOD, V106, P1460, DOI 10.1182-blood-2004-10-3982; Wood JC, 2008, MAGN RESON MED, V60, P82, DOI 10.1002-mrm.2166025
Does the death knell toll for phlebotomy in NAFLD? Reply
No full textThis study was supported by a Clinical Research Grant from the Raine Medical Research Foundation and the Western Australian Government Department of Health. Resonance Health Ltd (Claremont, Australia) provided support for the magnetic resonance scans.
Potential conflict of interest: Dr. St. Pierre is employed by, owns stock in, is on the speakers’ bureau for, and received grants from Resonance Health
Restitutio ad integrum : an 'Augustinian' reading of Jeremiah 31:31-34 in dialogue with the Christian tradition
No full textThe struggle to read Jer 31:31-34 as Christian Scripture has a long and divided history. Yet remarkably little has been done to grapple with the depth of this struggle in the Christian tradition from the post-Nicene period to the modern era. This thesis attempts to show the value of the tradition as an interlocutor for contemporary exegetical concerns in Christian readings and use of Jer 31:31-34. The study begins with Augustineâ s interpretation of the text as an absolute contrast between unbelief and faith, rather than the standard reading (found in Jerome) of a contrast between two successive religio-historical eras - one that governed Israel (the â old covenantâ ) and a new era and its covenant inaugurated in the coming of Christ. Augustineâ s absolute contrast loosened the strict temporal concern, so that the faithful of any era were members of the â new covenantâ . The study traces this reading of an absolute contrast in a few key moments of Christian interpretation: Thomas Aquinas and high medieval theology, then the 16th and 17th century Reformed tradition.
The thesis aims at a constructive reading of Jer 31:31-34, and so the struggle identified in these moments in the Christian tradition is brought into dialogue with modern critical discussions from Bernhard Duhm to the present. Finally I turn to an exegetical argument for an â Augustinianâ reading of the contrast of the covenants. The study finds that Jer 31:31-34, read in its role in Jeremiah, contrasts Israelâ s infidelity with a future idyllic faithfulness to Yhwh: in the new covenant all will be as it always ought to have been. The contrast is thus between two mutually exclusive standings before Yhwh. Thus the study aims to contribute to modern exegetical, theological and ecclesial discussions of â oldâ and â newâ covenants by examining one of the central texts of the discussion in dialogue with parts of the history of interpretation
Magnetic susceptibility of iron in malaria-infected red blood cells
No full textAbstractDuring intra-erythrocytic maturation, malaria parasites catabolize up to 80% of cellular haemoglobin. Haem is liberated inside the parasite and converted to haemozoin, preventing haem iron from participating in cell-damaging reactions. Several experimental techniques exploit the relatively large paramagnetic susceptibility of malaria-infected cells as a means of sorting cells or investigating haemoglobin degradation, but the source of the dramatic increase in cellular magnetic susceptibility during parasite growth has not been unequivocally determined. Plasmodium falciparum cultures were enriched using high-gradient magnetic fractionation columns and the magnetic susceptibility of cell contents was directly measured. The forms of haem iron in the erythrocytes were quantified spectroscopically. In the 3D7 laboratory strain, the parasites converted approximately 60% of host cell haemoglobin to haemozoin and this product was the primary source of the increase in cell magnetic susceptibility. Haemozoin iron was found to have a magnetic susceptibility of (11.0±0.9)×10−3 mL mol−1. The calculated volumetric magnetic susceptibility (SI units) of the magnetically enriched cells was (1.88±0.60)×10−6 relative to water while that of uninfected cells was not significantly different from water. Magnetic enrichment of parasitised cells can therefore be considered dependent primarily on the magnetic susceptibility of the parasitised cells
Magnetic interactions in native horse spleen ferritin below the superparamagnetic blocking temperature
No full textThalassaemic human spleen ferritin and haemosiderin in applied magnetic fields
No full textMössbauer spectra of the microcrystalline cores of thalassaemic human spleen ferritin and haemosiderin in applied magnetic fields have shown that the magnetic anisotropy dominates over the energy term arising from the net magnetic moments of the microcrystals in the applied field. The spectra have been analysed to give information on the net magnetic moments of the protein cores
The effect of temperature on the radial distribution function for iron in native horse spleen ferritin
No full textIron K-edge X-ray absorption spectra were recorded for a sample of freeze-dried horse spleen ferritin over a range of temperatures from 40 to 300 K. Gaussian-type radial distribution functions were fitted to the data from all temperatures simultaneously and the obtained mean-square relative displacements σ2 (EXAFS Debye-Waller factors) were fitted using an Einstein model. For iron atoms in the second and/or third coordination shell an Einstein temperature of 330 ± 20 K was obtained. If oxygen was assumed in the second or third shell, its Einstein temperature was 460 ± 20 K. This indicates that the core of ferritin may have a somewhat more rigid structure than those of previously studied ferritin analogues (polysaccharide iron complexes)
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