Recent results on achieving ferromagnetism in transition-metal-doped GaN, AlN and related materials are discussed. The field of semiconductor spintronics seeks to exploit the spin of charge carriers in new generations of transistors, lasers and integrated magnetic sensors. There is strong potential for new classes of ultra-low-power, high speed memory, logic and photonic devices based on spintronics. The utility of such devices depends on the availability of materials with practical magnetic ordering temperatures and most theories predict that the Curie temperature will be a strong function of bandgap. We discuss the current state-of-the-art in producing room temperature ferromagnetism in GaN-based materials, the origins of the magnetism and its potential applications.
We initially conducted a multicenter, randomized trial (n ¼ 43), and subsequently a questionnaire study (n ¼ 209) of participating hospitals, to evaluate whether infused fresh frozen plasma (FFP) could prevent the occurrence of hepatic veno-occlusive disease (VOD) after stem cell transplantation (SCT). Forty-three patients were divided into two groups: 23 receiving FFP infusions and 20 not receiving it. VOD developed in three patients not receiving FFP. Plasma von Willebrand factor (VWF) antigen levels were lower at days 0, 7 and 28 after SCT in patients receiving FFP than in those not receiving it, whereas plasma ADAMTS13 activity (ADAMTS13:AC) did not differ between them. Plasma VWF multimer (VWFM) was demonstrated to be defective in the highBintermediate VWFM during the early post-SCT phase, but there was a significant increase in high VWFM just before VOD onset. This suggests that a relative enzyme-tosubstrate (ADAMTS13/high-VWFM) imbalance is involved in the pathogenesis of VOD. To strengthen this hypothesis, the incidence of VOD was apparently lower in patients receiving FFP infusions than in those not receiving it (0/23 vs 3/20) in the randomized trial. Further, the results combined with the subsequent questionnaire study (0/36 vs 11/173) clearly showed the incidence to be statistically significant (0/59 vs 14/193, P ¼ 0.033).
Summary:Hepatic veno-occlusive disease (VOD) is a life-threatening complication after stem cell transplantation (SCT), characterized by thrombus formation in hepatic venules leading to a symptom triad of hyperbilirubinemia, hepatomegaly, and ascites. Multifactorial defects in the hemostatic system may contribute to its pathogenesis, but its remains to be investigated. Unusually large VWF multimers (UL-VWFMs), produced in and released from vascular endothelial cells, are most biologically active in the interaction with platelets under a high shear stress. UL-VWFMs are cleaved and degraded into smaller VWFMs by a specific liver producing plasma protease, termed VWF-cleaving protease (VWF-CPase), which has recently been identified as a metalloprotease solely produced in liver, termed ADAMTS13. Herein, we studied the correlation between plasma VWF-CPase activity and UL-VWFMs in 21 patients who received SCT, seven patients with VOD and 14 patients without VOD. In non-VOD patients, activities (mean ؎ 1s.d.) of VWF-CPase were 78 ؎ 17% of the control before the conditioning regimen, 76 ؎ 18% on day 0, 64 ؎ 19% on day 7, 57 ؎ 23% on day 14, 68 ؎ 13% on day 21 and 79 ؎ 19% on day 28 after SCT. The respective values in VOD patients were 32 ؎ 19%, 27 ؎ 15%, 18 ؎ 11%, 22 ؎ 18%, 26 ؎ 22% and 12 ؎ 4%. Thus, VWF-CPase activity was significantly reduced in VOD patients, even before the conditioning regimen, and such a difference was not found in other laboratory tests. However, despite such a clear difference, UL-VWFMs were present in plasmas of both patient groups, together with the increase of VWF antigen and ristocetin cofactor activity. These results indicate that the measurement of this enzyme activity is extremely useful in predicting the occurrence of VOD prior to a demonstration of its direct involvement in its pathogenesis.
Summary:In all, 100 unrelated donor bone marrow transplantations (UD-BMT) were performed in our institute between October 1993 and January 2003. Of 93 evaluable patients, 73 patients had hematological malignancy, 13 had nonmalignancy and seven had lymphoproliferative disease. The estimated 9-year event-free survival (EFS) rate was 57.175.5% in all patients. In the following analyses of the patients with hematological malignancy, the standard group had significantly better EFS than the high-risk group (61.577.0 vs 35.679.7%, P ¼ 0.02), and the EFS rate of the tacrolimus (FK-506) þ methotrexate (MTX)7methylprednisolone prophylactic group for graft-versus-host disease was superior to that of the FK-506 without MTX group (75.778.0 vs 55.877.6%, P ¼ 0.02). When we compared the EFS rates of the FK506 þ MTX7methylprednisolone (mPSL) group and the HLA-matched related donor BMT group in our institute, these were almost similar (75.778.1 vs 68.47 9.3%). Therefore, UD-BMT using FK-506 þ MTX7 mPSL is a safe and useful method for children with hematological malignancy who require allogeneic BMT.
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