RESUMO
Various upgrades have been completed at the XRD1 beamline at the Brazilian synchrotron light source (LNLS). The upgrades are comprehensive, with changes to both hardware and software, now allowing users of the beamline to conduct X-ray powder diffraction experiments with faster data acquisition times and improved quality. The main beamline parameters and the results obtained for different standards are presented, showing the beamline ability of performing high-quality experiments in transmission geometry. XRD1 operates in the 5.5-14â keV range and has a photon flux of 7.8 × 109â photonsâ s-1 (with 100â mA) at 12â keV, which is one of the typical working energies. At 8â keV (the other typical working energy) the photon flux at the sample position is 3.4 × 1010â photonsâ s-1 and the energy resolution ΔE/E = 3 × 10-4.
RESUMO
Chemotherapy-induced mucositis is an important dose-limiting and costly side effect for which there is no definitive prophylaxis or treatment. This is due in part to the lack of understanding of its pathophysiology and impact on intestinal function. The objectives of this study were to investigate the small intestine barrier function and electrolyte and water transport in an experimental model of methotrexate-induced mucositis, and to correlate these alterations with histological damage. Wistar rats were treated with methotrexate (1.5-3.5 mg/kg) for 3 days to induce mucositis. Intestinal permeability was measured by the urinary excretion rate of lactulose and mannitol following administration by gavage. Intestinal perfusion was performed in vivo for evaluation of water and electrolyte transports. Methotrexate-treated rats lost a significant amount of weight and presented a marked reduction in food intake. Methotrexate induced significant and dose-dependent villous atrophy and elongation of crypts in duodenum, jejunum, and ileum. Methotrexate also induced an increase in sodium and potassium secretion and an important reduction of the mucosa absorptive surface area, shown by the decrease in the mannitol excretion ratio. In conclusion, methotrexate caused major changes in small bowel function by disrupting intestinal permeability and inducing electrolyte secretion in parallel with substantial histological damage.