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Surgical stress and inflammatory response induce the release of catecholamines and PGs, which may be key factors in facilitating cancer recurrence through immunosuppression. Animal studies have suggested the efficacy of perioperative blockades of catecholamines and PGs in reducing immunosuppression. In this study, to our knowledge, we present the first report of the effects of perioperative propranolol and/or parecoxib on peripheral regulatory T cells (Tregs) in breast cancer patients. Patients were randomly assigned to control, propranolol, parecoxib, and propranolol plus parecoxib groups. We demonstrated that levels of circulating epinephrine, norepinephrine, and PGE2 increased in response to surgery. Meanwhile, peripheral FOXP3 mRNA level and Treg frequencies were elevated on postoperative day 7. Propranolol administration, rather than parecoxib, attenuated such elevation of Tregs, indicating the critical roles for catecholamines in surgery-induced promotion of Tregs. Besides, propranolol plus parecoxib treatment demonstrated no additive or synergistic effects. Furthermore, a study of Treg activity on CD4+ T cell responses to specific tumor Ags was performed in the control and propranolol groups. Propranolol abrogated the increased Treg activity and accompanying suppression of CD4+ T cell responses after surgery. Finally, we conducted ex vivo experiments on the effects of varying concentrations of epinephrine and/or propranolol on Treg proliferation over PBMCs from breast cancer patients, to provide further direct evidence strengthening our clinical observations. Epinephrine markedly promoted Treg proliferation, whereas propranolol prevented such enhancement effect. In conclusion, our study highlights beneficial roles for propranolol in inhibiting Treg responses in vivo and in vitro, and demonstrates that propranolol could alleviate surgical stress–induced elevation of Tregs in breast cancer patients.

Diode ideality factors of 2.0–8.0 have been reported in GaN-based p-n junctions. These values are much higher than the expected values of 1.0–2.0 as per the Sah-Noyce-Shockley theory. We propose a fundamentally new model for the high ideality factors obtained in GaN-based diodes. This model is based on the effect of moderately doped unipolar heterojunctions as well as metal–semiconductor junctions in series with the p-n junction. A relation for the effective ideality factor of a system of junctions is developed. A detailed experimental study is performed on diodes fabricated from two different structures, a bulk GaN p-n junction structure and a p-n junction structure incorporating a p-type AlGaN/GaN superlattice. Bulk GaN p-n junction diode displays an ideality factor of 6.9, whereas the one with the superlattice structure displays an ideality factor of 4.0. In addition, device simulation results further strengthen the model by showing that moderately doped unipolar heterojunctions are rectifying and increase the effective ideality factor of a p-n junction structure.

A novel approach to enhancing the emission efficiency of InGaN/GaN multiple quantum wells via coupling to surface plasmons (SPs) in a periodic two‐dimensional silver array is demonstrated. A higher internal quantum efficiency and a higher light extraction efficiency are simultaneously achieved by engraving an array of nanoholes into the p‐GaN cladding layer, followed by partial filling with silver. By top excitation and collection from the top of the Ag‐incorporated light emitting diodes (LEDs), a 2.8‐fold enhancement in peak photoluminescence intensity is demonstrated. The proposed nanoengraving technique offers a practical approach to overcoming the limitation of the exponentially decayed SP field without sacrificing the thickness of the p‐GaN layer and to controlling the effective coupling energy. The approach is feasible for high‐power lighting applications.

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