Study on the Hydrogen Effect and Interface/Border Traps of a Depletion-Mode AlGaN/GaN High-Electron-Mobility Transistor with a SiNx Gate Dielectric at Different Temperatures.

In this study, the electrical characteristics of depletion-mode AlGaN/GaN high-electron-mobility transistors (HEMTs) with a SiNx gate dielectric were tested under hydrogen exposure conditions. The experimental results are as follows: (1) After hydrogen treatment at room temperature, the threshold voltage VTH of the original device was positively shifted from -16.98 V to -11.53 V, and the positive bias of threshold was 5.45 V. When the VDS was swept from 0 to 1 V with VGS of 0 V, the IDS was reduced by 25% from 9.45 A to 7.08 A. (2) Another group of original devices with identical electrical performance, after the same duration of hydrogen treatment at 100 °C, exhibited a reverse shift in threshold voltage with a negative threshold shift of -0.91 V. The output characteristics were enhanced, and the saturation leakage current was increased. (3) The C-V method and the low-frequency noise method were used to investigate the effect of hydrogen effect on the device interface trap and border trap, respectively. It was found that high-temperature hydrogen conditions can passivate the interface/border traps of SiNx/AlGaN, reducing the density of interface/border traps and mitigating the trap capture effect. However, in the room-temperature hydrogen experiment, the concentration of interface/border traps increased. The research findings in this paper provide valuable references for the design and application of depletion-mode AlGaN/GaN HEMT devices.

Decreased immunosuppressive actions of 1α, 25-dihydroxyvitamin D3 in patients with immune thrombocytopenia.

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease. 1α, 25-dihydroxyvitamin D3 [1,25(OH)2D3] and vitamin D receptor (VDR) play important immune-suppressive roles in immune system. It has been reported that serum 1,25(OH)2D3 were lower in ITP patients. In this study, we evaluated local 1,25(OH)2D3 level and VDR mRNA expression further, and determined whether 1,25(OH)2D3/VDR were correlated with T cell dysfunction in ITP patients. We found that 1,25(OH)2D3/VDR levels were decreased in active ITP patients, and 1,25(OH)2D3 had significant anti-inflammatory effects on ITP patients, including both anti-proliferation of peripheral blood mononuclear cells (PBMCs) and reversing the abnormal T cells polarization. 1,25(OH)2D3 inhibited the differentiation of T helper (Th)1 and Tc1 cells but induced the differentiation of Th2, Tc2 and T regulatory (Treg) cells in ITP patients. However, the percentage of Th17 cells were not affected obviously with 1,25(OH)2D3. In addition, 1,25(OH)2D3 also suppressed pro-inflammatory cytokines (INF-γ and IL-17A) but promoted anti-inflammatory cytokine (IL-10) secretion in ITP patients. In conclusion, decreased 1,25(OH)2D3/VDR might participate in the pathogenesis of ITP, and appropriate supplement of 1,25(OH)2D3 may be a promising treatment.

Effects of the multidrug resistance-1 gene on drug resistance in primary immune thrombocytopenia.

Primary immune thrombocytopenia (ITP) is an autoimmune disorder that is characterized by low platelet count. Glucocorticoids (GCs) resistance is a great challenge in the treatment of ITP. P-glycoprotein (P-gp) is a widely studied protein, which is associated with drug resistance. However, in ITP, the functional activity and immune regulation mechanism of P-gp remain uncertain. In this study, we evaluated the expression and functional activity of P-gp in different lymphocyte subsets, explored the correlation between P-gp function and GCs resistance and investigated the role of P-gp in ITP pathogenesis. Results indicated that the functional activity and mRNA level of P-gp were significantly higher in GCs-nonresponsive patients than in GCs-responsive patients with ITP. However, these differences in P-gp were only significant in CD8+ T cells. P-gp function was related to disease activity rather than GCs therapy. P-gp was involved in secreting granzyme B and perforin, maintaining autoreactive lymphocytes survival and enhancing autologous platelets lysis in ITP. In conclusion, over-functional P-gp might play an important role in the pathogenesis of ITP and induce GCs resistance in nonresponsive ITP patients. The blockage of P-gp could be a promising therapeutic approach for GCs-resistant patients with ITP.

The Effect of Danazol in Primary Immune Thrombocytopenia: An Analysis of a Large Cohort From a Single Center in China.

AIM: This study assessed the long-term benefits and side effects of low-to-medium dose of danazol therapy in primary immune thrombocytopenia (ITP). METHODS: The retrospective analysis included 319 patients with ITP who accepted danazol therapy. Patients accepted danazol alone or in combination with glucocorticoids. Clinical outcome and tolerance were assessed in all patients. RESULTS: Among patients with persistent or chronic ITP, the overall response rate of danazol therapy was 65.0%. Sixty-five (63.1%) of the 103 patients reached remission with danazol alone, and 93 (48.7%) of the 191 patients who accepted combination therapies acquired remission and discontinued glucocorticoids successfully. Age and previous treatments were 2 risk factors for response rate. In newly diagnosed patients with ITP, the response rate and median response time did not differ significantly with or without danazol. However, the relapse rate was significantly lower in patients administered danazol combined with glucocorticoids than those accepted glucocorticoids alone. Totally, 21.1% of the patients experienced mild or moderate side effects, and 1.2% of the patients discontinued treatment due to intolerable side effects. CONCLUSION: Low-to-medium dosage of danazol is better tolerated and effective in patients with ITP, even in those refractory to other treatments. Combination of danazol and glucocorticoids for initial treatment may decrease relapse rates to achieve well-tolerated long-term remission.

Interleukin 35 may contribute to the loss of immunological self-tolerance in patients with primary immune thrombocytopenia.

Primary immune thrombocytopenia (ITP) is an autoimmune disorder. Interleukin-35 (IL35) can suppress T cell proliferation and elicit the development of inducible regulatory T cells (Tregs). Previous studies have shown decreased plasma IL35 levels and dysfunctional T cells in patients with ITP. In this study, we determined whether decreased IL35 levels correlate with T cell dysfunction in ITP patients. Plasma IL35 levels were found to be lower in ITP patients than in healthy controls, were positively correlated with platelet levels and the percentage of peripheral circulating Tregs, and negatively correlated with the levels of T helper-1 cells in ITP patients. We also evaluated the effects of IL35 on cytokines contributing to T cell proliferation. IL35 promoted the secretion of interleukin 10 (IL10) and transforming growth factor-ß1 but reduced the levels of interferon-γ and IL17A (also termed IL17). Moreover, IL35 inhibited the proliferation of CD4+ and CD8+ T cells but induced the differentiation and proliferation of Tregs in ITP. In summary, IL35 appears to contribute to the loss of immunological self-tolerance in ITP patients by modulating T cells and immunoregulatory cytokines.