Utilization of native oxygen in Eu(RE)-doped GaN for enabling device compatibility in optoelectronic applications.

The detrimental influence of oxygen on the performance and reliability of V/III nitride based devices is well known. However, the influence of oxygen on the nature of the incorporation of other co-dopants, such as rare earth ions, has been largely overlooked in GaN. Here, we report the first comprehensive study of the critical role that oxygen has on Eu in GaN, as well as atomic scale observation of diffusion and local concentration of both atoms in the crystal lattice. We find that oxygen plays an integral role in the location, stability, and local defect structure around the Eu ions that were doped into the GaN host. Although the availability of oxygen is essential for these properties, it renders the material incompatible with GaN-based devices. However, the utilization of the normally occurring oxygen in GaN is promoted through structural manipulation, reducing its concentration by 2 orders of magnitude, while maintaining both the material quality and the favorable optical properties of the Eu ions. These findings open the way for full integration of RE dopants for optoelectronic functionalities in the existing GaN platform.

Corticosteroid therapy in patients with IgA nephropathy and impaired renal function.

AIM: IgA nephropathy (IgAN) is a common type of primary glomerulonephritis that constitutes a major cause of end-stage renal disease. Oral and/or intravenous glucocorticoid therapy can protect against progression of IgAN in patients with preserved renal function. We evaluated steroid therapy in IgAN with established renal dysfunction. PATIENTS AND METHODS: We retrospectively analyzed the effect of methylprednisolone (MP) pulse therapy in 8 IgAN patients with serum creatinine concentrations (sCr) 2.76 +/- 1.32 mg/dl (mean +/- SD). In each patient renal function had progressively deteriorated in the 12 months preceding treatment, as indicated by negative slopes of 1/sCr plotted against time (regression coefficients). RESULTS: Regression coefficients during the 12 months following therapy improved significantly from -0.02333 +/- 0.00732 to -0.00036 +/- 0.00423 dl/mg/month, respectively. The mean difference in slope was 0.0230 +/- 0.0076 dl/mg/month (95% confidence interval, 0.0165 to 0.0295, p < 0.001). Proteinuria also significantly decreased from a mean urine protein/creatinine ratio of 2.57 +/- 1.12 before therapy to 1.12 +/- 0.84 6 months after therapy (p < 0.005). Other factors that might affect progression of renal dysfunction remained unchanged during the observation periods. CONCLUSION: Corticosteroids may attenuate progression of renal failure and delay the need for dialysis in this patient population, although a large randomized trial is necessary.

Pentavalent technetium-99m-dimercaptosuccinic acid scintigraphy in renal osteodystrophy.

Pentavalent 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy and 99mTc-hydroxymethylene diphosphonate (HMDP) bone scan were performed in one patient with renal osteodystrophy (ROD) before and after vitamin D3 pulse therapy. The bone scan showed diffusely increased tracer uptake in the whole skeleton, and no change of tracer distribution was noted before or after vitamin D3 pulse therapy. However, 99mTc(V)-DMSA scintigraphy revealed diffusely increased tracer uptake in the whole skeleton before therapy, and markedly decreased tracer uptake in the bones was seen at 5 mo after therapy. Increased uptake of 99mTc(V)-DMSA was observed at 7 mo after therapy, which reflected the laboratory findings. Technetium-99m-(V)-DMSA scintigraphy appeared to be more sensitive than the conventional 99mTc-HMDP bone scan in assessing the characteristics and therapeutic effect of bone disease in ROD.

Evaluation of blood coagulation-fibrinolysis system in patients receiving chronic hemodialysis.

We determined plasma levels of thrombomodulin, thrombin-antithrombin III complex (TAT), protein C, protein S, and plasmin-alpha 2 plasmin inhibitor complex (PIC) before and after hemodialysis in 54 patients receiving chronic hemodialysis, to evaluate the blood-coagulation system and to evaluate the antithrombogenicity of various dialyzer membranes. Predialysis levels of thrombomodulin and TAT were both significantly increased compared with normal control values, but levels of protein C, protein S, and PIC were not changed. In patients dialyzed with ethylene vinyl alcohol (EVAL) and polysulfone membranes, postdialysis levels of thrombomodulin, TAT, protein C, protein S, and PIC were not significantly different from the predialysis levels. However, in patients dialyzed with regenerated cellulose and polymethyl-methacrylate (PMMA) membranes, postdialysis levels of thrombomodulin, TAT, and PIC were significantly higher than predialysis levels. We conclude that patients on maintenance hemodialysis were considered to be in a state of hypercoagulability before hemodialysis, and a single hemodialysis session using regenerated cellulose and PMMA membrane may have caused injury to vascular endothelial cells, hypercoagulability, and enhancement of fibrinolytic activity.