We report on the magnetoresistive properties of all-oxide tunnel spin valves in which electrodes of mixed valence manganites (La0.7Sr0.3MnO3) are separated by a thin insulating layer. The structures were prepared by Pulsed Laser Deposition and several tunnel barriers were used including PrBa2(CuGa)3O7, CeO2 and SrTiO3. The latter gives the largest magnetoresistive effect where the trilayer's resistance is increased by a factor of 5.5 at 50 Gauss and 4.2 K. Analysis of the temperature variation of the barrier resistivity shows that the dramatic loss of the magnetoresistive effect above 150 K is due to a reduced oxygen content of the interface between La0.7Sr0.3MnO3 and SrTiO3. Solving this problem should lead to similar results at room temperature.

Recovery from radiation-induced (RI) myelosuppression depends on hematopoietic stem and progenitor cell survival and the active proliferation/differentiation process, which requires early cytokine support. Single cytokine or late-acting growth factor therapy has proved to be inefficient in ensuring reconstitution after severe RI damage. This work was aimed at evaluating the in vivo survival effect of combinations of early-acting cytokines whose antiapoptotic activity has been demonstrated in vitro: stem cell factor (SCF [S]), FMS-like tyrosine kinase 3 ligand (FLT-3 ligand [F]), thrombopoietin (TPO [T]), interleukin-3 (IL-3 [3]), and stromal derived factor-1 (SDF-1). B6D2F1 mice underwent total body irradiation at 8 Gy cesium Cs 137 ␥ radiation (ie, lethal dose 90% at 30 days) and were treated soon after irradiation, at 2 hours and at 24 hours, with recombinant murine cytokines, each given intraperitoneally at 50 g/kg per injection. All treatments induced 30-day survival rates significantly higher than control (survival rate, 8.3%). 4F (SFT3) and 5F (4F ؉ SDF-1) were the most efficient combinations (81.2% and 87.5%, respectively), which was better than 3F (SFT, 50%), TPO alone (58.3%), and SDF-1 alone (29.2%) and also better than 4F given at 10 g/kg per injection (4F10, 45.8%) or as a 50 g/kg single injection at 2 hours (4Fs, 62.5%). Despite delayed death occurring mainly from day 150 on and possible long-term hematopoiesis impairment, half the 30-day protective effects of 4F and 5F were preserved at 300 days. Our results show that short-and long-term survival after irradiation depends on appropriate multiple cytokine combinations and at optimal concentrations. The proposal is made that an emergency cytokine regimen could be applied to nuclear accident victims as part of longer cytokine treatment, cell therapy, or both. (Blood. 2003;

No abstract

No abstract

Cutaneous radiation syndrome (CRS) is the delayed consequence of localized skin exposure to high doses of ionizing radiation. Here we examined for the first time in a large animal model the therapeutic potential of autologous adipose tissue-derived stroma cells (ASCs). For experiments, Göttingen minipigs were locally gamma irradiated using a 60Co source at the dose of 50 Gy and grafted (n = 5) or not (n = 8). ASCs were cultured in MEM-alpha with 10% fetal calf serum and basic fibroblast growth factor (2 ng.mL−1) and post irradiation were intradermally injected on days 25, 46, 67 and finally between days 95 and 115 (50×106 ASCs each time) into the exposed area. All controls exhibited a clinical evolution with final necrosis (day 91). In grafted pigs an ultimate wound healing was observed in four out of five grafted animals (day 130 +/− 28). Immunohistological analysis of cytokeratin expression showed a complete epidermis recovery. Grafted ASCs accumulated at the dermis/subcutis barrier in which they attracted numerous immune cells, and even an increased vasculature in one pig. Globally this study suggests that local injection of ASCs may represent a useful strategy to mitigate CRS.