Characterization of a submicro-X-ray fluorescence setup on the B16 beamline at Diamond Light Source

An X-ray fluorescence setup has been tested on the B16 beamline at the Diamond Light Source synchrotron with two different excitation energies (12.7 and 17 keV). This setup allows the scanning of thin samples (thicknesses up to several micrometers) with a sub-micrometer resolution (beam size of 500 nm × 600 nm determined with a 50 µm Au wire). Sensitivities and detection limits reaching values of 249 counts s−1 fg−1 and 4 ag in 1000 s, respectively (for As Kα excited with 17 keV), are presented in order to demonstrate the capabilities of this setup. Sample measurements of a human bone and a single cell performed at B16 are presented in order to illustrate the suitability of the setup in biological applications.</jats:p

temporary implementation and testing of a confocal sr μxrf system for bone analysis at the x ray fluorescence beamline at elettra

Abstract The confocal μ XRF spectrometer of Atominstitut (ATI) was transported and set up at the X-ray Fluorescence beamline at Elettra - Sincrotrone Trieste. It was successfully adjusted to the incoming beam (9.2 keV). Test measurements on a free-standing Cu wire were performed to determine the size of the focused micro-beam (non-confocal mode, 56 × 35 μ m 2 ) and the size of the confocal volume (confocal mode, 41 × 24 × 34 μ m 2 ) for the Cu–K α emission. In order to test the setup's capabilities, two areas on different human bone samples were measured in confocal scanning mode. For one of the samples the comparison with a previous μ XRF measurement, obtained with a low power X-ray tube in the lab, is presented

Detection and imaging of gadolinium accumulation in human bone tissue by micro- and submicro-XRF

Gadolinium-based contrast agents (GBCAs) are frequently used in patients undergoing magnetic resonance imaging. In GBCAs gadolinium (Gd) is present in a bound chelated form. Gadolinium is a rare-earth element, which is normally not present in human body. Though the blood elimination half-life of contrast agents is about 90 minutes, recent studies demonstrated that some tissues retain gadolinium, which might further pose a health threat due to toxic effects of free gadolinium. It is known that the bone tissue can serve as a gadolinium depot, but so far only bulk measurements were performed. Here we present a summary of experiments in which for the first time we mapped gadolinium in bone biopsy from a male patient with idiopathic osteoporosis (without indication of renal impairment), who received MRI 8 months prior to biopsy. In our studies performed by means of synchrotron radiation induced micro- and submicro-X-ray fluorescence spectroscopy (SR-XRF), gadolinium was detected in human cortical bone tissue. The distribution of gadolinium displays a specific accumulation pattern. Correlation of elemental maps obtained at ANKA synchrotron with qBEI images (quantitative backscattered electron imaging) allowed assignment of Gd structures to the histological bone structures. Follow-up beamtimes at ESRF and Diamond Light Source using submicro-SR-XRF allowed resolving thin Gd structures in cortical bone, as well as correlating them with calcium and zinc

Uncoupling of sexual reproduction from homologous recombination in homozygous Oenothera species

Salient features of the first meiotic division are independent segregation of chromosomes and homologous recombination (HR). In non-sexually reproducing, homozygous species studied to date HR is absent. In this study, we constructed the first linkage maps of homozygous, bivalent-forming Oenothera species and provide evidence that HR was exclusively confined to the chromosome ends of all linkage groups in our population. Co-segregation of complementary DNA-based markers with the major group of AFLP markers indicates that HR has only a minor role in generating genetic diversity of this taxon despite its efficient adaptation capability. Uneven chromosome condensation during meiosis in Oenothera may account for restriction of HR. The use of plants with ancient chromosomal arm arrangement demonstrates that limitation of HR occurred before and independent from species hybridizations and reciprocal translocations of chromosome arms—a phenomenon, which is widespread in the genus. We propose that consecutive loss of HR favored the evolution of reciprocal translocations, beneficial superlinkage groups and ultimately permanent translocation heterozygosity

Schrittmacher-Therapie der hypertroph-obstruktiven Kardiomyopathie. PIC-Studiengruppe. [Pacemaker therapy of hypertrophic obstructive cardiomyopathy. PIC (Pacing in Cardiomyopathy) Study Group]

Clinical management of patients with symptoms caused by pharmacological refractory hypertrophic obstructive cardiomyopathy must consider surgical myectomy, percutaneous transluminal septal myocardial ablation and implantation of a DDD pacemaker. Until now, no prospective, double blind, randomized studies have yet been carried out to determine the merits of each of these treatment alternatives. However, uncontrolled studies have shown that short atrioventricular delay dual-chamber pacing reduces outflow tract obstruction. Aim of the study was to investigate the results of the pacemaker therapy in a prospective, double blind randomized crossover procedure. All patients with hypertrophic obstructive cardiomyopathy included in this multicenter study were either refractory or intolerant to drugs and typically had pressure gradients higher than 30 mm Hg. In 83 patients, mean age 53 (18 to 82) years who responded favorably to a temporary pacing test, a DDD pacemaker was implanted. After echo- and echo-Doppler-based measurements of hemodynamic parameters the patients were randomized into 2 groups, those with an implanted pacemaker in the inactivated mode (AAI) and those with a pacemaker in the activated mode (DDD with optimized short AV delay). A crossover of these groups was performed after 12 and 24 weeks, respectively. Both objective parameters of echo including Doppler, and spiroergometry, and subjective parameters of angina, dyspnea, and quality of life were recorded. Additionally, subgroups based on age decades were analyzed. After 12 weeks in the DDD mode, regardless of the randomization sequence, a decrease of the pressure gradient from 59 +/- 36 mm Hg (median) to 30 +/- 25 mm Hg was proven significant (p &lt; 0.001). The endurance of the patients who, during screening, achieved less than 10 minutes of exercise by the Bruce protocol improved by 21% under DDD mode. The main symptoms, as measured by the NYHA classification, improved statistically significant from a mean of 2.4 to 1.7 for functional class, from a mean of 2.4 to 1.4 for dyspnea and from a mean of 1.0 to 0.4 for angina. Subgroup analysis showed improvements depended significantly upon age, with a marked improvement between the ages of 60 and 70, which was statistically significant as compared to other decades. Subjective improvements in the quality-of-life of patients was measured using a specially developed questionnaire. These findings justify, by all means, the intention to implant a DDD pacemaker in older patients. In younger and/or such patients with elevated pressure gradients, the results of ongoing randomized studies comparing myectomy, PTSMA and pacing have to be considered