Mycophenolate mofetil-related gastrointestinal mucosal injury in multivisceral transplantation

Mycophenolate mofetil (MMF) has become an important and commonly used drug for maintenance immunosuppression therapy in recipients of all types of organ transplants. The drug is an antimetabolite that blocks the de novo pathway of purine synthesis. Although it selectively inhibits B- and T-lymphocyte proliferation, enterocytes are partially susceptible to MMF. One of the main limitations of this drug is gastrointestinal toxicity, with diarrhea the most frequently reported adverse effect. Most studies of MMF-associated gastrointestinal toxicity have been performed in patients with solid-organ transplants, although no data on changes related to MMF toxicity in bowel allografts have been published in the English literature. We evaluated mucosal intestinal biopsy tissue from patients with multivisceral transplants receiving MMF therapy. Our objective was to find morphologic changes that might be attributed to MMF toxicity, as well as changes that could differentiate MMF toxicity from acute rejection. Examination of the surface epithelium, lamina propria, and crypts in this small group of patients showed no specific changes that could be associated with MMF toxicity. Changes such as graft-vs-host disease or inflammatory bowel disease described in previous studies of solid-organ transplantation were not observed. Larger studies and the use of special stains and new markers might be necessary to characterize possible patterns of MMF toxicity and their differences from acute rejection

Modifying the Size of Nickel Metallic Particles by H 2

The effect of a reduction process with CO or H2 on the size of nickel particles in Ni/ZrO2 dry methane reforming catalysts have been studied by means of in situ X-ray Absorption Spectroscopy (XAS) and Diffuse Reflectance FTIR Spectroscopy (DRIFTS). Our results clearly indicate that a high temperature treatment with CO increases the dispersion of the nickel metallic phase. XAS results have shown a lower coordination number of Ni in the sample treated with CO than that reduced with H2. From the DRIFTS results, it can be established that, under the CO treatment, the formation of Ni(CO)4 complexes corrodes the nickel particles, decreasing their size. The formation of these gas molecules occurs without measurable losses of nickel from the catalyst which maintains the same nickel content after the hydrogen or the CO treatment at high temperature. Therefore, this airborne nickel compound, by colliding with the zirconia surface, must deposit the nickel metal atoms around onto the support. This behavior is evidence of an important interaction between nickel and zirconia surface as unlike other supports there is no losses of nickel during the dispersion process on zirconia. Although different effects of CO on nickel catalysts have been previously described, we have found for the first time several experimental evidences demonstrating the whole redispersion phenomenon.Ministerio de Educación y Ciencia ENE2007-67926-C02-01Junta de Andalucía P07-FQM-0252

A Measurement of Pi-Polarization at Lep

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