A direct method for 55Fe activity measurement

A simple, direct method for the determination of ⁵⁵Fe activity using liquid scintillation counting is described. The method is based on the theoretical calculation of counting efficiencies and does not make use of efficiency tracing or extrapolation.     

Superparamegnetic iron oxides for MRI

Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous adminstration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrydtalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. Correspondence to: R. Weissleder     

52 additional reference population samples for the 55 AISNP panel

Ancestry inference for a person using a panel of SNPs depends on the variation of frequencies of those SNPs around the world and the amount of reference data available for calculation/comparison. The Kidd Lab panel of 55 AISNPs has been incorporated in commercial kits by both Life Technologies and Illumina for massively parallel sequencing. Therefore, a larger set of reference populations will be useful for researchers using those kits. We have added reference population allele frequencies for 52 population samples to the 73 previously entered so that there are now allele frequencies publicly available in ALFRED and FROG-kb for a total of 125 population samples.     

Half-life measurement of 55Fe.

The half-life of 55Fe was determined experimentally and compared with literature values. A solid 55Fe source was prepared by electrodeposition and repeatedly measured in an X-ray detector at a constant, low solid angle. In total, more than six hundred measurements were performed over a period of ten months, corresponding to one third of the half-life. The experimental method and the corresponding uncertainty budget are presented. The result of 1005.2+/-1.4 days is slightly higher than the current recommended values.     

人工关节置换治疗高龄股骨粗隆间骨折体会

采用人工股骨头置换治疗高龄股骨粗隆间骨折55例。术后以髋关节疼痛、行走、功能、运动-肌力、日常生活能力5方面作为评定指标,经过6个月-5年随访,优良率为94.54%。     

微米级超顺磁性氧化铁颗粒在细胞影像学上的应用

细胞影像学是指借助影像学方法在活体内无创可重复性地显示靶细胞生物学行为,并对其进行定量和定性研究的科学[1],是影像学从大体形态显像走向细胞分子显像的重大突破.目前,细胞影像技术主要包括核医学成像、MRI及光学成像等[1].     

Training for cross-country skiing and iron status

Effects of iron supplements and training for cross-country skiing on hematological and iron status were studied in nine men and ten women from the U. S. Nordic ski team. Four men and five women received a multiple vitamin, multiple mineral supplement containing 18 mg iron for 8 months while five men and five women received a placebo. Fasting blood samples were taken from all skiers prior to supplementation (May) and in August, November, and January. Hemoglobin, hematocrit, plasma iron, total iron binding capacity (TIBC), percentage of transferrin saturation, serum ferritin, free erythrocyte porphyrin, and haptoglobin were measured on each sample. Hemoglobin, hematocrit, and TIBC were higher in November when both men and women skiers trained at altitude than in August. In January TIBC was further increased, haptoglobin was increased, hemoglobin for the men fell below May levels, and hematocrit returned to May levels. Skiers receiving iron had lower TIBC levels in November and January than the placebo group. Six women and two men had ferritin levels below 28 ng X ml-1, which suggests prelatent iron deficiency. Free erythrocyte porphyrin levels above 100 micrograms X dl-1 RBC were found in all skiers at some point during training. The results suggest that multivitamin, multimineral supplements containing iron have little effect on the iron status of cross-country skiers.     

Production of cobalt-55, a short-lived,positron emitting radiolabel for bleomycin

The production and radiochemical separation of ⁵⁵Co from deuteron irradiation of enriched ⁵⁴Fe target is described. Methods used for the recovery and reuse of the target material (⁵⁴Fe) are also described. The yield of ⁵⁵Co at 12 MeV incident deuteron energy is 1.7 mCi per μAh at end of bombardment and the contamination with ⁵⁷Co is 0.016%. The ⁵⁵Co produced is chelated to bleomycin and used for tumour imaging with a positron emission tomographic camera based on multi-wire proportional chamber detectors.     

Indium and iron as tracers for erythroid precursors

External visualization and delineation of functional bone marrow is important for diagnostic, prognostic and therapeutic purposes. Because of difficulties in using the isotopes of iron for bone-marrow imaging, indium-111 chloride has been used extensively for this purpose. In this investigation we attempted to solve the problem of cellular localization of indium chloride by employing a rat model with erythropoietic precursors selectively damaged by lethal intracellular radiation from the Auger electrons of Fe-55. In the rat, we have shown that the absolute marrow uptakes of indium and iron are different, whereas the absolute uptakes of indium and sulfur colloid are the same. However, in animals whose erythroid activity was partially destroyed with Fe-55, the fractional depressions of iron and indium uptakes were the same and corresponded to the extent of the remaining erythroid activity. In addition, following an in vitro separation of the cellular elements of marrow with iron carbonyl, both iron and indium were found in the erythroid-rich supernatant, whereas sulfur colloid was in the precipitate. These results indicate that, in the rat, In-111 chloride is an effective in vivo marker for the early phases of iron uptake by the bone marrow.     

Clinical MRI for iron detection in Parkinson's disease

We studied nonheme iron in Parkinson's disease (PD) using clinically available MRI in 36 patients and 21 healthy volunteers. The subjects underwent thorough clinical investigation, including 3-T MRI. Quantitative R2* was able to reflect symptoms of PD. In addition, the clinically used susceptibility-weighted imaging differentiated between controls and patients, whereas T₂-weighted imaging did not. Disease-related changes were present not only in substantia nigra but also in globus pallidus. Such changes are associated with neurodegeneration, reflecting the severity of motor impairment.     

Adiabatic pulse preparation for imaging iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles produce changes in the surrounding microscopic magnetic field. A method for generating contrast based on the application of an adiabatic preparation pulse and the failure of the adiabatic condition surrounding the nanoparticles is introduced in this article. Images were obtained in the presence and absence of an adiabatic preparation pulse and the difference was obtained. With the use of an adiabatic full passage pulse, the contrast in the difference image depends linearly on iron concentration up to 1 mM. The use of an adiabatic zero passage pulse resulted in higher sensitivity to nanoparticles compared to the adiabatic full passage, while maintaining linear concentration dependence to 0.1 mM. This technique was shown to be insensitive to magnetization transfer and B(0) inhomogeneity. With its linearity with iron concentration and insensitivity to changes in the main magnetic field, the new method is well suited for quantitative iron oxide nanoparticle imaging.     

Increasing the reference populations for the 55 AISNP panel: the need and benefits

Ancestry inference for an individual can only be as good as the reference populations with allele frequency data on the SNPs being used. If the most relevant ancestral population(s) does not have data available for the SNPs studied, then analyses based on DNA evidence may indicate a quite distantly related population, albeit one among the more closely related of the existing reference populations. We have added reference population allele frequencies for 14 additional population samples (with >1100 individuals studied) to the 125 population samples previously published for the Kidd Lab 55 AISNP panel. Allele frequencies are now publicly available for all 55 SNPs in ALFRED and FROG-kb for a total of 139 population samples. This Kidd Lab panel of 55 ancestry informative SNPs has been incorporated in commercial kits by both ThermoFisher Scientific and Illumina for massively parallel sequencing. Researchers employing those kits will find the enhanced set of reference populations useful.

     

The production of 55Fe with medium-energy protons

Thick-target production rates of ⁵⁵Fe produced in the proton bombardment of Mn, Co and Ni were investigated from threshold up to 100 MeV. Impurity levels of the only radiocontaminant of importance, ⁵⁹Fe, were also considered. It is shown that the optimum production rate at energies above ∼ 35 MeV will be achieved by utilizing a tandem Mn/Ni target. Theoretical calculations performed with the computer code ALICE/85/300 were found to be in good agreement with the measured ⁵⁵Fe thick-target production-rate curves.