8 research outputs found
Determination of the elemental distribution of human joint bones by SR micro-XRF
No full textIn humans the toxic trace element lead (Pb) mainly accumulates in the skeletal tissue where it resides for a long period. Although Pb is known to play a role in bone and cartilage diseases, the distribution of Pb in these tissues is mostly unknown. Therefore synchrotron-radiation-induced micro x-ray fluorescence analysis (SR m-XRF) in various geometries was used to determine the distributions of Pb, Ca, Zn and Sr at the cartilage-bone interface in human femoral heads and patellae. SR m-XRF results were matched with backscattered electron (BE) images providing information on structural features of the tissue. Conventional SR m-XRF at HASYLAB beamline L showed that Pb mostly accumulates in a zone of some micrometers around the transition between non-calcified and calcified cartilage. However, the relatively large sample thickness did not allowmore precise conclusions. Exploiting the 3D capabilities of confocal SR m-XRF and SR microfluorescence tomography at ANKA Fluo-Topo beamline and HASYLAB beamline L, the spatial resolution could be improved and a highly specific accumulation of Pb at the tidemark, the calcification front between non-calcified and calcified cartilage,was detected. Itwas found that Pb and Zn accumulation coincide at the tidemark. Since the tidemark plays an important role in osteoarthritis, the results may strengthen other authors’ conclusions that Pb is associated with this joint disease. Although offering less spatial resolution when compared tomicro-tomography, confocal SR m-XRF is best suited for such studies. It facilitates the comparison of element maps with other imaging techniques like BE imaging
Improved micro x-ray fluorescence spectrometer for light element analysis
No full text(or μg/cm²) were obtained by measuring various thin metal foils under different conditions
Investigation of Dose Rates Exterior to an Above-Ground Waste Storage Facility Using Radiation Transport Models
No full textAssessment of chemical species of lead accumulated in tidemarks of human articular cartilage by X-ray absorption near-edge structure analysis
No full textA highly specific accumulation of the toxic element lead was recently measured
in the transition zone between non-calcified and calcified normal human
articular cartilage. This transition zone, the so-called ‘tidemark’, is considered to
be an active calcification front of great clinical importance. However, little is
known about the mechanisms of accumulation and the chemical form of Pb in
calcified cartilage and bone. Using spatially resolved X-ray absorption near-edge
structure analysis (m-XANES) at the Pb L3-edge, the chemical state of Pb in the
osteochondral region was investigated. The feasibility of the m-XANES set-up
at the SUL-X beamline (ANKA synchrotron light source) was tested and
confirmed by comparing XANES spectra of bulk Pb-reference compounds
recorded at both the XAS and the SUL-X beamline at ANKA. The m-XANES
set-up was then used to investigate the tidemark region of human bone (two
patella samples and one femoral head sample). The spectra recorded at the
tidemark and at the trabecular bone were found to be highly correlated with the
spectra of synthetic Pb-doped carbonated hydroxyapatite, suggesting that in
both of these very different tissues Pb is incorporated into the hydroxyapatite
structure
Test-retest reliability of pulmonary oxygen uptake and muscle deoxygenation during moderate- and heavy-intensity cycling in youth elite-cyclists
No full textThis is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordTo establish the test-retest reliability of pulmonary oxygen uptake ( O2), muscle
deoxygenation (deoxy[heme]) and tissue oxygen saturation (StO2) kinetics in youth elitecyclists.
From baseline pedaling, 15 youth cyclists completed 6-min step transitions to a
moderate- and heavy-intensity work rate separated by 8 min of baseline cycling. The protocol
was repeated after 1 h of passive rest. O2 was measured breath-by-breath alongside
deoxy[heme] and StO2 of the vastus lateralis by near-infrared spectroscopy. Reliability was
assessed using 95% limits of agreement (LoA), the typical error (TE) and the intraclass
correlation coefficient (ICC). During moderate- and heavy-intensity step cycling, TEs for the
amplitude, time delay and time constant ranged between 3.5-21.9% and 3.9-12.1% for O2 and
between 6.6-13.7% and 3.5-10.4% for deoxy[heme], respectively. The 95% confidence interval
for estimating the kinetic parameters significantly improved for ensemble-averaged transitions
of O2 (p<0.01) but not for deoxy[heme]. For StO2, the TEs for the baseline, end-exercise and
the rate of deoxygenation were 1.0-42.5% and 1.1-5.5% during moderate- and heavy-intensity
exercise, respectively. The ICC ranged from 0.81-0.99 for all measures. Test-retest reliability
data provides limits within which changes in O2, deoxy[heme] and StO2 kinetics may be
interpreted with confidence in youth athletes
Bone material quality in transiliac bone biopsies of postmenopausal osteoporotic women after 3 years of strontium ranelate treatment
No full textEffects of EMFs from Undersea Power Cables on Elasmobranchs and Other Marine Species.
No full textAnthropogenic electromagnetic fields (EMFs) have been introduced into the marine environmentaround the world and from a wide variety of sources for well over a century. Despite this, littleis known about potential ecological impacts from EMFs. For decades, power transmissioncables have been installed across bays and river mouths, and connecting near-shore islands to themainland, with little consideration of possible effects to marine species from EMFs. At a time ofgreater environmental awareness, the US now faces the possibility of a new source of EMFs overa much greater extent of the seabed from offshore renewable energy facilities in coastal waters.This literature review synthesizes information on the types of power cables and models theexpected EMFs from representative cables. Available information on electro- and magnetosensitivityof marine organisms, including elasmobranchs (sharks and rays) and other fishspecies, marine mammals, sea turtles, and invertebrates is summarized and used in conjunctionwith the power cable modeling results to evaluate the level of confidence the existing state ofknowledge provides for impact assessment. Gaps in our knowledge of power cablecharacteristics and the biology needed to understand and predict impacts are summarized andform the basis of recommendations for future research priorities. Potential mitigationopportunities are described with a discussion of their potential secondary impacts as well assuggested methods for monitoring mitigation effectiveness. Finally, because interest in offshorerenewable energy has increased throughout US coastal waters, there is a concern that organismscould be exposed to multiple seabed power cables. Cumulative effects of this exposure are discussed
