Spectroscopic Studies in InGaN Quantum Wells

Fundamental electronic modulations in strained wurtzite III-nitride, in particular InxGa1−xN, quantum wells (QWs) were treated to explore the reason why practical InGaN devices emit bright luminescences in spite of the large threading dislocation (TD) density. The emission mechanisms were shown to vary depending on the well thickness L and InN molar fraction x. The electric field across the QW plane, F, which is a sum of the fields due to spontaneous and piezoelectric polarization and the pn junction field, causes the redshift of the ground state resonance energy through the quantum confined Stark effect (QCSE). The absorption spectrum is modulated by QCSE, quantum-confined Franz-Keldysh effect (QCFK), and Franz-Keldysh (FK) effect from the barrires when, for the first approximation, potential drop across the well (FL) exceeds the valence band discontinuity, EV. Under large FL, holes are confined in the triangular potential well formed at one side of the well. This produces apparent Stokes-like shift in addition to the in-plane net Stokes shift on the absorption spectrum. The QCFK and FK further modulate the electronic structure of the wells with L greater than the three dimensional (3D) free exciton (FE) Bohr radius, aB. When FL exceeds EC, both electron (e) and hole (h) confined levels drop into the triangular potential wells at opposite sides of the wells, which reduces the wavefunction overlap. Doping of Si in the barriers partially screens the F resulting in a smaller Stokes-like shift, shorter recombination decay time, and higher emission efficiency. Finally, the use of InGaN was found to overcome the field-induced oscillator strength lowering due to the spontaneous and piezoelectric polarization. Effective in-plane localization of the QW excitons (confined excitons, or quantized excitons) in quantum disk (Q-disk) size potential minima, which are produced by nonrandom alloy potential fluctuation enhanced by the large bowing parameter and F, produces confined e-h pairs whose wavefunctions are still overlapped when L<aB. Their Coulomb interaction is more pronounced for FL<EV.

Increased CXCL10 expression in nasal fibroblasts from patients with refractory chronic rhinosinusitis and asthma

BACKGROUND

Chronic rhinosinusitis (CRS) is characterized by local inflammation of the sinonasal tissues. CRS patients with nasal polyps and asthma often develop acute exacerbation of sinonasal symptoms after upper respiratory tract infections. However, the influence of concomitant asthma on the nasal immune response to viral infection remains unclear.

METHODS

Specimens of nasal polyp and mucosal tissues were obtained from 3 groups of CRS patients (n = 14 per group): 1) patients without asthma (CRS group), 2) patients with aspirin-tolerant asthma (ATA group), and 3) patients with aspirin-intolerant asthma (AIA group). Nasal fibroblasts isolated from the specimens were stimulated with poly I:C. CXCL10 expression was analyzed by the quantitative real-time polymerase chain reaction and enzyme-linked immunoadsorbent assay. Biopsy specimens from CRS patients without asthma were subjected to immunohistochemistry for detection of T-bet and GATA-3 expression in CD3+ T cells by double labeling.

RESULTS

Nasal fibroblasts from the ATA and AIA groups showed significantly enhanced expression of CXCL10 mRNA and protein after poly I:C stimulation compared with cells from the CRS group and the control group (normal nasal mucosa). In addition to T helper (Th)2 cells, there was more abundant infiltration of Th1 cells into tissues from the AIA and ATA groups.

CONCLUSIONS

Our findings suggest that CRS associated with asthma may become intractable through the over-production of CXCL10 in response to viral infection.

Local bandgap control of germanium by silicon nitride stressor

We have proposed a new approach to tune the operation wavelength of Franz-Keldysh Ge electro-absorption modulation in Si photonics by controlling the local strain environment to cover the whole range of C + L bands (1.53 - 1.62 μm). The present paper shows a proof of strain-tuning modulator concept by the shift of the Ge absorption edge using SiN(x) stressor films and Franz-Keldysh effect in strain-controlled Ge.

Alternaria inhibits double-stranded RNA-induced cytokine production through Toll-like receptor 3

BACKGROUND

Fungi may be involved in asthma and chronic rhinosinusitis (CRS). Peripheral blood mononuclear cells from CRS patients produce interleukin (IL)-5, IL-13 and interferon (IFN)-γ in the presence of Alternaria. In addition, Alternaria produces potent Th2-like adjuvant effects in the airway. Therefore, we hypothesized that Alternaria may inhibit Th1-type defense mechanisms against virus infection.

METHODS

Dendritic cells (DCs) were generated from mouse bone marrow. The functional responses were assessed by expression of cell surface molecules by FACS (MHC class II, CD40, CD80, CD86 and OX40L). Production of IL-6, chemokine CXCL10 (IP-10), chemokine CXCL11 (I-TAC) and IFN-β was measured by ELISA. Toll-like receptor 3 (TLR3) mRNA and protein expression was detected by quantitative real-time PCR and Western blot.

RESULTS

Alternaria and polyinosinic-polycytidylic acid (poly I:C) enhanced cell surface expression of MHC class II, CD40, CD80, CD86 and OX40L, and IL-6 production in a concentration-dependent manner. However, Alternaria significantly inhibited production of IP-10, I-TAC and IFN-β, induced by viral double-stranded RNA (dsRNA) mimic poly I:C. TLR3 mRNA expression and protein production by poly I:C were significantly inhibited by Alternaria. These reactions are likely caused by heat-stable factor(s) in Alternaria extract with >100 kDa molecular mass.

CONCLUSION

These findings suggest that the fungus Alternaria may inhibit production of IFN-β and other cytokines by DCs by suppressing TLR3 expression. These results indicate that Alternaria may inhibit host innate immunity against virus infection.

The octadecaneuropeptide stimulates somatolactin release from cultured goldfish pituitary cells

The present study aimed to investigate the distribution of the octadecaneuropeptide (ODN) in the goldfish brain and to look for a possible effect of ODN on somatolactin (SL) release from pituitary cells. A discrete population of ODN-immunoreactive neurones was localised in the lateral part of the nucleus lateralis tuberis. These neurones sent projections through the neurohypophyseal tract towards the neurohypophysis, and nerve fibres were seen in the close vicinity of SL-producing cells in the pars intermedia. Incubation of cultured goldfish pituitary cells with graded concentrations of ODN (10(-9) -10(-5 ) m) induced a dose-dependent stimulation of SL-β, but not SL-α, release. ODN-evoked SL release was blocked by the metabotrophic endozepine receptor antagonist cyclo(1-8) [DLeu(5) ]OP but was not affected by the central-type benzodiazepine receptor antagonist flumazenil. ODN-induced SL release was suppressed by treatment with the phospholipase C (PLC) inhibitor U-73122 but not with the protein kinase A (PKA) inhibitor H-89. These results indicate that, in fish, ODN produced by hypothalamic neurones acts as a hypophysiotrophic neuropeptide stimulating SL release. The effect of ODN is mediated through a metabotrophic endozepine receptor positively coupled to the PLC/inositol 1,4,5-trisphosphate/protein kinase C-signalling pathway.

Alternaria Inhibits Defense Mechanism for Virus Infection

Objective: It has been suggested that fungi may have trigger effects for CRS. It was reported that PBMCs from CRS patients produced IL-5, IL-13 and INF-gamma by Alternaria. Kobayashi reported that Alternaria produced potent Th2-like adjuvant effects in the airway. We hypothesized that Alternaria inhibits Th1-type defense mechanisms against virus infection.

Method: The functional responses were assessed by expression of cell surface molecules by FACS (MHC Class II, CD40, CD80, CD86, OX40L and CCR7). IL-6, IP-10, and I-TAC were measured by ELISA kits (R&D Systems). TLR3 mRNA and protein expression were detected by real time–PCR and Western blotting.

Results: Alternaria and Poly I:C induced surface molecules of MHC Class II, CD40, CD80, CD86, OX40L, and CCR7 and IL-6 production in a concentration-dependent manner. But, Alternaria significantly inhibited IP-10, I-TAC, and IFN-gamma production induced by Poly I:C. TLR3 mRNA expression and protein production by Poly I:C were significantly inhibited by Alternairia. It was considered that these reactions were caused by heat-resistance and over 100 molecular weight substance from Alternaria.

Conclusion: From these results, it was found that the presence of Alternaria inhibited a production of IFN-gamma by inhibiting expression of TLR3 and inhibited a production of IP -10 and I-TAC. Alternaria inhibits defense mechanisms against virus infection. It was suggested that Alternaria caused suppression for innate immune systems.

Clinical Trend of Churg-Strauss Syndrome in Japan

Objective: There are a lot of reports that LTRA internal use, steroid medicine, and weight loss are associated with the onset of CSS. Because we experienced 2 cases of CSS that occurred during treatment of eosinophilic sinusitis this time, in addition, we consider some discussion from the literature.

Method: We examined retrospectively 2 eosinophilic sinusitis patients, one with asthma and the other with allergic rhinitis. After these operations, we added wash-out sinuses and prescribed LTRA and nasal steroids. Depending on the state of intranasal findings, we gave steroid medicine.

Results: We performed wash-out sinuses, LTRA internal use, and nasal steroids as postoperative treatment with both cases, and, at the exacerbation of intranasal findings, the intranasal findings improved by administration of steroid medicine. When we took steroid medicine, we did not do it with fixed quantity and the administration method that we did it and reduced. CSS was diagnosed by mononeuritis multipleand polyarthritis and purpuric onset subsequently. We suggested the possibility that LTRA internal use was associated with the onset of the CSS.

Conclusion: LTRA internal use, steroid medicine, and weight loss may be associated with the onset of the CSS, and it is important to discontinue a causing agent when the otolaryngologist who frequently prescribes these drugs grasps overall status, and suspects CSS.

Alternaria fungus induces the production of GM-CSF, interleukin-6 and interleukin-8 and calcium signaling in human airway epithelium through protease-activated receptor 2

RATIONALE

Recent studies suggest that host immune responses to environmental fungi may play an important role in the development of allergic diseases, such as human asthma. Epithelium is considered an active participant in allergic inflammation. We previously reported that aspartate protease from Alternaria induces the activation and degranulation of human eosinophils that are mediated through protease-activated receptor 2 (PAR-2). However, our current knowledge on the innate immune responses of epithelium to environmental fungi is very limited. We investigated the responses of epithelium to fungi and the mechanisms of these responses.

METHODS

Human airway epithelial cell line BEAS-2B and Calu-3 (both from American Type Culture Collection) were incubated with PAR-2 peptides and extracts of various fungi. The cellular responses, including GM-CSF, interleukin (IL)-6, IL-8, eotaxin, eotaxin-2 and RANTES production as well as increases in intracellular calcium concentration ([Ca(2+)](i)), were examined. To characterize the proteases involved in these responses, protease inhibitors such as pepstatin A and alkalo-thermophilic Bacillus inhibitor (ATBI), HIV protease inhibitors and 4-amidinophenylmethanesulfonyl fluoride hydrochloride were used. To investigate the role of PAR-2, PAR-2-agonistic and PAR-2-antagonistic peptides were used.

RESULTS

PAR-2-activating peptide, but not the control peptide, induced GM-CSF, IL-6 and IL-8 production; these cellular responses were accompanied by a quick and marked increase in [Ca(2+)](i). Among 7 common environmental fungi, only Alternaria induced GM-CSF, IL-6 and IL-8 production and increased [Ca(2+)](i) response. Both cytokine production and increased [Ca(2+)](i) were significantly inhibited by PAR-2 antagonist peptide and by aspartate protease inhibitors (pepstatin A, ritonavir, nelfinavir and ATBI), but not by the PAR-2 control peptide or by other protease inhibitors.

CONCLUSIONS

Aspartate proteases from Alternaria induce cytokine production and calcium response in airway epithelium that is mediated through PAR-2. This protease-mediated activation of airway epithelium may be implicated in the development and exacerbation of airway allergic disease.