Broadband generation of quasi bound-state-in-continuum modes using subwavelength truncated cone resonators

To allow a high quality factor (Q-factor) to a sub-wavelength dielectric resonator, quasi-bound states in the continuum (Q-BICs) have gained much interest. However, the Q-BIC resonance condition is too sensitive to the geometry of the resonator, and its practical broadband generation on a single-wafer platform has been limited. Here we present that, employing the base angle as a structural degree of freedom, the truncated nano-cone resonator supports the Q-BIC resonance with a high Q-factor of >150 over a wide wavelength range of >100 nm. We expect our approach will boost the utilization of the Q-BIC resonance for various applications requiring broadband spectral tuning.

Strain Engineering of Low-Dimensional Materials for Emerging Quantum Phenomena and Functionalities

Recent discoveries of exotic physical phenomena, such as unconventional superconductivity in magic-angle twisted bilayer graphene, dissipationless Dirac fermions in topological insulators, and quantum spin liquids, have triggered tremendous interest in quantum materials. The macroscopic revelation of quantum mechanical effects in quantum materials is associated with strong electron-electron correlations in the lattice, particularly where materials have reduced dimensionality. Owing to the strong correlations and confined geometry, altering atomic spacing and crystal symmetry via strain has emerged as an effective and versatile pathway for perturbing the subtle equilibrium of quantum states. This review highlights recent advances in strain-tunable quantum phenomena and functionalities, with particular focus on low-dimensional quantum materials. Experimental strategies for strain engineering are first discussed in terms of heterogeneity and elastic reconfigurability of strain distribution. The nontrivial quantum properties of several strain-quantum coupled platforms, including 2D van der Waals materials and heterostructures, topological insulators, superconducting oxides, and metal halide perovskites, are next outlined, with current challenges and future opportunities in quantum straintronics followed. Overall, strain engineering of quantum phenomena and functionalities is a rich field for fundamental research of many-body interactions and holds substantial promise for next-generation electronics capable of ultrafast, dissipationless, and secure information processing and communications.

Electrically driven strain-induced deterministic single-photon emitters in a van der Waals heterostructure

Quantum confinement in transition metal dichalcogenides (TMDCs) enables the realization of deterministic single-photon emitters. The position and polarization control of single photons have been achieved via local strain engineering using nanostructures. However, most existing TMDC-based emitters are operated by optical pumping, while the emission sites in electrically pumped emitters are uncontrolled. Here, we demonstrate electrically driven single-photon emitters located at the positions where strains are induced by atomic force microscope indentation on a van der Waals heterostructure consisting of graphene, hexagonal boron nitride, and tungsten diselenide. The optical, electrical, and mechanical properties induced by the local strain gradient were systematically analyzed. The emission at the indentation sites exhibits photon antibunching behavior with a g⁽²⁾(0) value of ~0.3, intensity saturation, and a linearly cross-polarized doublet, at 4 kelvin. This robust spatial control of electrically driven single-photon emitters will pave the way for the practical implementation of integrated quantum light sources.

Polarization Control of Deterministic Single-Photon Emitters in Monolayer WSe2

Single-photon emitters, the basic building blocks of quantum communication and information, have been developed using atomically thin transition metal dichalcogenides (TMDCs). Although the bandgap of TMDCs was spatially engineered in artificially created defects for single-photon emitters, it remains a challenge to precisely align the emitter's dipole moment to optical cavities for the Purcell enhancement. Here, we demonstrate position- and polarization-controlled single-photon emitters in monolayer WSe₂. A tensile strain of ∼0.2% was applied to monolayer WSe₂ by placing it onto a dielectric rod structure with a nanosized gap. Excitons were localized in the nanogap sites, resulting in the generation of linearly polarized single-photon emission with a g⁽²⁾ of ∼0.1 at 4 K. Additionally, we measured the abrupt change in polarization of single photons with respect to the nanogap size. Our robust spatial and polarization control of emission provides an efficient way to demonstrate deterministic and scalable single-photon sources by integrating with nanocavities.

Recent advances in nanocavities and their applications

High quality factor and small mode volume in nanocavities enable the demonstration of efficient nanophotonic devices with low power consumption, strong nonlinearity, and high modulation speed, due to the strong light-matter interaction. In this review, we focus on recent state-of-the-art nanocavities and their applications. We introduce single nanocavities including semiconductor nanowires, plasmonic cavities, and nanostructures based on quasi-bound states in the continuum (quasi-BIC), for laser, photovoltaic, and nonlinear applications. In addition, nanocavity arrays with unique feedback mechanisms, including BIC cavities, parity-time symmetry coupled cavities, and photonic topological cavities, are introduced for laser applications. These various cavity designs and underlying physics in single and array nanocavities are useful for the practical implementation of promising nanophotonic devices.

Recent Progress in Nanolaser Technology

Nanolasers are key elements in the implementation of optical integrated circuits owing to their low lasing thresholds, high energy efficiencies, and high modulation speeds. With the development of semiconductor wafer growth and nanofabrication techniques, various types of wavelength-scale and subwavelength-scale nanolasers have been proposed. For example, photonic crystal lasers and plasmonic lasers based on the feedback mechanisms of the photonic bandgap and surface plasmon polaritons, respectively, have been successfully demonstrated. More recently, nanolasers employing new mechanisms of light confinement, including parity-time symmetry lasers, photonic topological insulator lasers, and bound states in the continuum lasers, have been developed. Here, the operational mechanisms, optical characterizations, and practical applications of these nanolasers based on recent research results are outlined. Their scientific and engineering challenges are also discussed.

Effectiveness of Autologous Fat Graft in Treating Fecal Incontinence

Purpose

The most common risk factor for fecal incontinence (FI) is obstetric injury. FI affects 1.4%–18% of adults. Most patients are unaware when they are young, when symptoms appear suddenly and worsen with aging. Autologous fat graft is widely used in cosmetic surgical field and may substitute for injectable bulky agents in treating FI. Authors have done fat graft for past several years. This article reports the effectiveness of the fat graft in treating FI and discusses satisfaction with the procedure.

Methods

Fat was harvested from both lateral thighs using 10-mL Luer-loc syringe. Pure fat was extracted from harvests and mixed with fat, oil, and tumescent through refinement. Fats were injected into upper border of posterior ano-rectal ring, submucosa of anal canal and intersphincteric space. Thirty-five patients with FI were treated with this method from July 2016 to February 2017 in Busan Hangun Hospital. They were 13 male (mean age, 60.8 years) and 22 female patients (mean age, 63.3 years). The Wexner score was checked before procedure. We evaluated outcome in outpatients by asking the patients. For 19 patients we checked the Wexner score after procedure.

Results

Symptom improved in 29 (82.9%), and not improved in 6 (17.1%). In 2 of 6 patients, they felt better than before procedure, although not satisfied. No improvement in 4. Mean Wexner score was 9.7 before procedure. There were no serious complications such as inflammation or fat embolism.

Conclusion

Autologous fat graft can be an effective alternative treatment for FI. It is safe and easy to perform, and cost effective.

Unique Scattering Properties of Silicon Nanowires Embedded with Porous Segments

The development of advanced imaging tools is important for the investigation of the fundamental properties of nanostructures composed of single or multiple nanomaterials. However, complicated preparation processes and irreversible alterations of the samples to be examined are inevitable in most current imaging techniques. In this work, we developed a simple method based on polarization-resolved light scattering measurements to characterize the structural and optical properties of complex nanomaterials. In particular, we examined a single Si nanowire embedded with porous Si segments, in which the porous Si could not be easily distinguished from solid Si by scanning electron microscopy. The dark-field optical images and polarization-resolved scattering spectra showed unique optical features of porous and solid Si. In particular, the porosity, diameter, and number of porous Si segments in the single Si nanowire were identified from the scattering measurements. In addition, we performed systematic optical simulations based on the effective medium model in individual porous and solid Si nanowires. A good agreement between the simulation and measurement results enabled the estimation of the structural parameters of the nanowires, such as diameter and porosity. We believe that our method will be useful for analyzing the structural and optical properties of nanomaterials prior to using complicated and uneconomical imaging tools.

Photon-Triggered Current Generation in Chemically-Synthesized Silicon Nanowires

A porous Si segment in a Si nanowire (NW), when exposed to light, generates a current with a high on/off ratio. This unique feature has been recently used to demonstrate photon-triggered NW devices including transistors, logic gates, and photodetection systems. Here, we develop a reliable and simple procedure to fabricate porous Si segments in chemically synthesized Si NWs for photon-triggered current generation. To achieve this, we employ 100 nm-diameter chemical-vapor-deposition grown Si NWs that possess an n-type high doping level and extremely smooth surface. The NW regions uncovered by electron-beam resist become selectively porous through metal-assisted chemical etching, using Ag nanoparticles as a catalyst. The contact electrodes are then fabricated on both ends of such NWs, and the generated current is measured when the laser is focused on the porous Si segment. The current level is changed by controlling the power of the incident laser and bias voltage. The on/off ratio is measured up to 1.5 × 10⁴ at a forward bias of 5 V. In addition, we investigate the porous-length-dependent responsivity of the NW device with the porous Si segment. The responsivity is observed to decrease for porous segment lengths beyond 360 nm. Furthermore, we fabricate nine porous Si segments in a single Si NW and measure the identical photon-triggered current from each porous segment; this single NW device can function as a high-resolution photodetection system. Therefore, our fabrication method to precisely control the position and length of the porous Si segments opens up new possibilities for the practical implementation of programmable logic gates and ultrasensitive photodetectors.

Sensitization to various minor house dust mite allergens is greater in patients with atopic dermatitis than in those with respiratory allergic disease

BACKGROUND

Various allergenic proteins are produced by house dust mites (HDM). However, the allergenicity and clinical implications of these allergens are unknown.

OBJECTIVE

The purpose of this study was to identify allergens in Dermatophagoides farinae and elucidate the sensitization profiles to these in Korean patients suffering from respiratory (allergic rhinitis and/or asthma) and atopic dermatitis symptoms.

METHODS

IgE reactivities in sera from 160 HDM allergy patients were analysed by one- and two-dimensional gel electrophoresis and immunoblotting. IgE-reactive components were identified by liquid chromatography-coupled electrospray ionization-tandem mass spectrometry. Nine recombinant mite allergens (Der f 1, Der f 2, Der f 10, Der f 11, Der f 13, Der f 14, Der f 30, Der f 32 and Der f Alt a 10) were produced, and the IgE reactivity in sera to each was determined by ELISAs.

RESULTS

Der f 1 and Der f 2 were recognized by IgE in serum samples from 88.1% and 78.1% of all patients, respectively. Patients with respiratory allergies were mainly sensitized to these major allergens, whereas patients with atopic dermatitis symptoms showed polysensitization to major and minor allergen components (including Der f 11, Der f 13, Der f 14, Der f 32 and Der f Alt a 10).

CONCLUSIONS

Patients with respiratory allergic disease sensitize to major allergen components of HDM. Those with atopic dermatitis were sensitized to a broader range of minor allergen components of HDM (Der f 11, Der f 13, Der f 14, Der f 32 and Der f Alt a 10).

Enhancement of Light Absorption in Silicon Nanowire Photovoltaic Devices with Dielectric and Metallic Grating Structures

We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si₃N₄ grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si₃N₄ gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer. Furthermore, we demonstrate Si nanowire photovoltaic devices with Ag gratings using the same transfer method. Measurements on the fabricated devices reveal approximately 27.1% enhancement in light absorption compared to that of the same devices without the Ag gratings without any degradation of electrical properties. We believe that our polymer-assisted transfer method is not limited to the fabrication of grating-incorporated nanowire photovoltaic devices but can also be generically applied for the implementation of complex nanoscale structures toward the development of multifunctional optoelectronic devices.

Association between Systolic Blood Pressure after Thrombolysis and Early Neurological Improvement in Ischaemic Stroke Patients

Introduction

This study aimed to evaluate the relationship between systolic blood pressures (SBPs) within 12 hours after intravenous recombinant tissue plasminogen activator (rtPA) treatment and early neurological outcomes.

Methods

This was a retrospective observational study of acute ischaemic stroke (AIS) patients who received intravenous rtPA administration. SBPs at the time of rtPA bolus and thereafter every hour were collected. The mean, standard deviation, and coefficient of variation values of SBP during the periods of 0-2 h, 2-6 h, and 6-12 h were calculated. The primary outcome was major neurologic improvement (MNI) at 24 hours after thrombolysis.

Results

Serial measures of SBPs revealed different 12-hour courses between the patients with and without MNI. The difference of SBP tendency was statistically significant (p=0.013). In univariate analysis, patients with MNI showed lower levels of mean SBPs during the periods of 2-6 h and 6-12 h (p=0.030 and p=0.005, respectively), and higher frequency of very early neurologic improvement (VENI) at the end of rtPA infusion (p<0.001). In logistic regression analysis, VENI at 1 h, mean SBP value during 6-12 h, and atrial fibrillation were independently related to MNI at 24 h.

Conclusions

SBP level during the first 12 hours after intravenous rtPA treatment may be an important clinical factor that is associated with early neurological improvement of AIS patients.

Switching of Photonic Crystal Lasers by Graphene

Unique features of graphene have motivated the development of graphene-integrated photonic devices. In particular, the electrical tunability of graphene loss enables high-speed modulation of light and tuning of cavity resonances in graphene-integrated waveguides and cavities. However, efficient control of light emission such as lasing, using graphene, remains a challenge. In this work, we demonstrate on/off switching of single- and double-cavity photonic crystal lasers by electrical gating of a monolayer graphene sheet on top of photonic crystal cavities. The optical loss of graphene was controlled by varying the gate voltage V_g, with the ion gel atop the graphene sheet. First, the fundamental properties of graphene were investigated through the transmittance measurement and numerical simulations. Next, optically pumped lasing was demonstrated for a graphene-integrated single photonic crystal cavity at V_g below -0.6 V, exhibiting a low lasing threshold of ∼480 μW, whereas lasing was not observed at V_g above -0.6 V owing to the intrinsic optical loss of graphene. Changing quality factor of the graphene-integrated photonic crystal cavity enables or disables the lasing operation. Moreover, in the double-cavity photonic crystal lasers with graphene, switching of individual cavities with separate graphene sheets was achieved, and these two lasing actions were controlled independently despite the close distance of ∼2.2 μm between adjacent cavities. We believe that our simple and practical approach for switching in graphene-integrated active photonic devices will pave the way toward designing high-contrast and ultracompact photonic integrated circuits.

Bright Room-Temperature Single-Photon Emission from Defects in Gallium Nitride

Room-temperature quantum emitters in gallium nitride (GaN) are reported. The emitters originate from cubic inclusions in hexagonal lattice and exhibit narrowband luminescence in the red spectral range. The sources are found in different GaN substrates, and therefore are promising for scalable quantum technologies.

Ranitidine-induced anaphylaxis: clinical features, cross-reactivity, and skin testing

BACKGROUND

Histamine H2 receptor antagonists are commonly prescribed medications and are known to be well tolerated. However, 99 cases of ranitidine-induced anaphylaxis occurred in Korea from 2007 to 2014.

OBJECTIVE

The purpose of this study was to determine the incidence, clinical features, and diagnostic methods for ranitidine-induced anaphylaxis.

METHODS

Ranitidine-related pharmacovigilance data from 2007 to 2014 were reviewed. Adverse drug reactions with causal relationships were selected, and clinical manifestations, outcomes, and drug-related information were assessed. For further investigation, 8 years of pharmacovigilance data were collected at a single centre. Twenty-three patients participated in in vivo and in vitro studies. Skin tests, oral provocation tests, and laboratory tests were performed, including tests using other kinds of histamine H2 receptor antagonists.

RESULTS

Over 7 years, 584 patients suffered adverse reactions to ranitidine. The most common manifestation was cutaneous symptoms. Among them, 99 patients (17.0%) experienced anaphylaxis. In a single-centre study, skin prick tests were positive in 91.7% of ranitidine-induced anaphylaxis patients (11/12); the optimal concentration was 20 mg/mL. Detection of ranitidine-specific immunoglobulin E failed. Cimetidine and proton pump inhibitors showed no cross-reactivity with ranitidine based on the skin prick test, oral provocation test, or clinical determination. Surprisingly, 82.6% of patients reintroduced ranitidine and re-experienced the same adverse reactions because ranitidine was not considered the culprit drug.

CONCLUSIONS AND CLINICAL RELEVANCE

Although ranitidine is known as a safe drug, it can also cause diverse adverse reactions, including anaphylaxis. This study demonstrates the need to pay attention to adverse reactions to ranitidine and consider ranitidine as a cause of anaphylaxis.

Resonant magneto-optic Kerr effects of a single Ni nanorod in the Mie scattering regime

We present a systematic, theoretical investigation of the polar magneto-optical (MO) Kerr effects of a single Ni nanorod in the Mie regime. The MO Kerr rotation, ellipticity, amplitude ratio, and phase shift are calculated as a function of the length and width of the nanorod. The electric field amplitude ratio of the MO Kerr effect is locally maximized when the nanorod supports a plasmonic resonance in the polarization state orthogonal to the incident light. The plasmonic resonances directly induced by the incident light do not enhance the amplitude ratio. In the Mie regime, multiple local maxima of the MO Kerr activity are supported by the resonant modes with different modal characteristics. From the viewpoint of first-order perturbation analysis, the spatial overlap between the incident-light-induced electric field and the Green function determines the local maxima.

Full three-dimensional power flow analysis of single-emitter-plasmonic-nanoantenna system

We present a full three-dimensional (3D) power flow analysis of an emitter-nanoantenna system. A conventional analysis, based on the total Poynting vector, calculates only the coupling strength in terms of the Purcell enhancement. For a better understanding of the emitter-nanoantenna system, not only the Purcell enhancement but also complete information on the energy transfer channels is necessary. The separation of the pure scattering and emitter output Poynting vectors enables the quantification of the individual energy transfer channels. Employing the finite-difference time-domain method (FDTD), we examine a nanodisk antenna that supports the bright dipole and dark quadrupole resonance modes for which the power flow characteristics are completely distinct, and we analyze the power flow enhancements to the energy transfer channels with respect to the wavelength, polarization, and position of the emitter coupled to the antenna. The 3D power flow analysis reveals how the constructive or destructive interference between the emitter and the antenna resonance mode affects the power flow enhancements and the far-field radiation pattern. Our proposed power flow analysis should play a critical role in characterizing the emitter-antenna system and customizing its energy transfer properties for desired applications.

A twin-free single-crystal Ag nanoplate plasmonic platform: hybridization of the optical nano-antenna and surface plasmon active surface

Surface plasmons based on metallic nanostructures enable light manipulation beyond the optical diffraction limit. We have epitaxially synthesized twin-free single-crystal Ag nanoplates on SrTiO3 substrates. Unlike the nanoplates synthesized in a solution phase, these nanoplates have perfectly clean surfaces as well as a quite large size of tens of micrometers. As-synthesized defect-free single-crystal Ag nanoplates have an atomically flat surface and sides with well-defined angles, allowing long distance propagation of surface plasmons and highly reliable plasmonic integration. By spatially separating receiving and transmitting antennas and plasmonically interfacing them, the signal quality of transmission/reception can be largely improved. Furthermore, by combining sub-dimensional nanostructures onto the two-dimensional space effective hierarchical plasmonic nano-complexes can be built up. Theoretical simulations well reproduced unique experimental results of coupling between SPPs and free-space radiation by the nanoplate antenna sides, low-loss long-range SPP propagation, and tunneling or scattering of SPPs at a nano-gap as well as a nano-structure introduced on the nanoplate. The single-crystal Ag nanoplate will find superb applications in plasmonic nano-circuitry and lab-on-a-chip for biochemical sensing.

Design of plasmonic nano-antenna for total internal reflection fluorescence microscopy

We propose a gold modified bow-tie plasmonic nano-antenna, which can be suitably used in combination with total internal reflection fluorescence microscopy. The plasmonic nano-antenna, supporting well-separated multiple resonances, not only concentrates the total internal reflection evanescent field at the deep subwavelength scale, but also enhances fluorescence emission by the Purcell effect. Finite-difference time-domain computations show that the enhancement of the excitation light strongly correlates with the far-field radiation pattern radiated from the antenna. Depending on the antenna geometry, the resonant modes are widely tuned and their wavelengths can be easily matched to the diverse emission or excitation wavelengths of fluorophores.

A double-strip plasmonic waveguide coupled to an electrically driven nanowire LED

We demonstrate the efficient integration of an electrically driven nanowire (NW) light source with a double-strip plasmonic waveguide. A top-down-fabricated GaAs NW light-emitting diode (LED) is placed between two straight gold strip waveguides with the gap distance decreasing to 30 nm at the end of the waveguide and operated by current injection through the p-contact electrode acting as a plasmonic waveguide. Measurements of polarization-resolved images and spectra show that the light emission from the NW LED was coupled to a plasmonic waveguide mode, propagated through the waveguide, and was focused onto a subwavelength-sized spot of surface plasmon polaritons at the tapered end of the waveguide. Numerical simulation agreed well with these experimental results, confirming that a symmetric plasmonic waveguide mode was excited on the top surface of the waveguide. Our demonstration of a plasmonic waveguide coupled to an electrically driven NW LED represents important progress toward further miniaturization and practical implementation of ultracompact photonic integrated circuits.

Allergenicity of recombinant profilins from Japanese hop, Humulus japonicus

BACKGROUND AND OBJECTIVE

Pollen from Japanese hop, Humulusjaponicus, is a major cause of pollinosis in Korea. Profilin (15 kDa) from Humulus scandens has been associated with strong allergenicity in allergic Chinese patients. Profilin has also been detected in pollen extract from Korean Japanese hop by proteomic analysis and immunoglobulin (Ig) E immunoblotting. However, the allergenicity of allergens isolated from Japanese hop has not been investigated in Korean individuals. This study was undertaken to produce recombinant profilin from Japanese hop and evaluate its allergenicity.

METHODS

Complementary DNA sequences encoding 2 isoallergens were cloned by reverse transcription polymerase chain reaction and their recombinant proteins expressed in Escherichia coli. The IgE-binding reactivities of the recombinant allergens were assessed by enzyme-linked immunosorbent assay.

RESULTS

The deduced amino acid sequences of the H. japonicus profilins were 68.7% to 80.2% homologous with profilins from mugwort (Art v 4), ragweed (Amb a 14), and birch (Bet v 2). Two isoallergens of profilin from H. japonicus were 78.2% identical. Notably, the cDNA sequences of these 2 isoallergens were 98.5% (AY268422) and 98.7% (AY268424) identical to those of H. scandens. Serum samples from Japanese hop-sensitized individuals showed 12.9% IgE reactivity to both of the recombinant profilin isoallergens from H. japonicus, indicating that profilin may not be an allergenically dominant component of Japanese hop pollen. The recombinant profilins showed only 0% to 9.3% inhibition of the crude extract.

CONCLUSIONS

Two isoallergens of profilin that are highly conserved with those of mugwort, ragweed, and birch were identified in H. japonicus. Profilins from Japanese hop pollen may play a minor role in the pathogenesis of pollinosis in Koreans.

Nanobeam photonic bandedge lasers

We demonstrate one-dimensional nanobeam photonic bandedge lasers with InGaAsP quantum wells at room temperature from the lowest dielectric band of photonic crystal nanobeam waveguides. The incident optical power at threshold is 0.6 mW (effectively ~18 μW). To confirm the lasing from the dielectric bandedge, the polarization and the photoluminescent spectra are taken from nanobeams of varying lattice constants. The observed shift of the lasing wavelength agrees well with the computational prediction.

Wavelength-scale photonic-crystal laser formed by electron-beam-induced nano-block deposition

A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.

Characterization of the major allergens of Pachycondyla chinensis in ant sting anaphylaxis patients

BACKGROUND

The ant species Pachycondyla chinensis, which has spread from Far Eastern Asia to New Zealand and North America, induces anaphylactic reactions in human with its sting. However, the major allergens of P. chinensis have not yet been characterized.

METHODS

We selected seven patients with histories of anaphylaxis induced by P. chinensis. Two-dimensional electrophoresis (2-DE) was used to identify the major allergens. We subsequently performed Western blots for P. chinensis-specific IgEs, N-terminal amino acid sequencing, ESI-MS/MS, and RT-PCR using primers based on the N-terminal sequence.

RESULTS

Six of the anaphylactic subjects had an IgE specific to a 23 kDa allergen of P. chinensis. Two candidates for major allergens, 23 kDa (pI 8.7) and 25 kDa (pI 6.2), were revealed by 2-DE using P. chinensis-specific IgE immunoblotting. In N-terminal sequencing and ESI-MS/MS analysis, 23 kDa (pI 8.7) and 25 kDa (pI 6.2) allergens, belonging to the protein families of antigen 5, were identified and share marked amino acid sequence similarity. The 23 kDa allergen is 206 amino acids in length and homology searches showed 54.0% and 50.0% homology with Sol i 3 and Ves v 5, respectively.

CONCLUSION

The major allergens of P. chinensis are 23 kDa (pI 8.7) and 25 kDa (pI 6.2) proteins that belong to the antigen 5 family of proteins.

Modal characteristics in a single-nanowire cavity with a triangular cross section

In this study, the modal characteristics of a single-GaN nanowire cavity with a triangular cross section surrounded by air or located on a silicon dioxide substrate have been analyzed. Two transverse resonant modes, transverse electric-like and transverse magnetic-like modes, are dominantly excited for nanowire cavities that have a small cross-sectional size of <300 nm and length of 10 microm. Using the three-dimensional finite-difference time-domain simulation method, quality factors, confinement factors, single-mode conditions, and far-field emission patterns are investigated for a nanowire cavity as a function of one length of the triangular cross section. The results of these simulations provide information that will be vital for the design and development of efficient nanowire lasers and light sources in ultracompact nanophotonic integrated circuits.

Regulation of German cockroach extract-induced IL-8 expression in human airway epithelial cells

BACKGROUND

Cockroaches have been known as a cause of respiratory allergies such as asthma. IL-8 plays an integral role in the coordination and persistence of the inflammatory process in the chronic inflammation of the airways in asthma.

OBJECTIVE

We investigated the mechanism by which German cockroach extract (GCE) triggers IL-8 release from human airway epithelial cells.

METHODS

Chemical inhibitors were pretreated before addition of GCE for promoter activity and protein synthesis of IL-8. The Transcriptional activity of IL-8 promoter was analysed by mutational, deletional anaylsis and electrophoretic mobility shift assay (EMSA).

RESULTS

Stimulation of H292 cells with GCE resulted in a time- and concentration-dependent induction of IL-8 transcription and protein synthesis. IL-8 promoter deletion analysis indicated that position -132 to +41 was essential for GCE-induced IL-8 transcription, and mutants with substitutions in activator protein (AP)-1, nuclear factor (NF)-IL6 and NF-kappaB-binding sites revealed a requirement for NF-kappaB and NF-IL6, but not AP-1, in GCE-induced activation of the IL-8 promoter. The DNA-binding activities of NF-kappaB and NF-IL6 were induced by GCE, as determined by EMSA. The chemical inhibition of extracellular signal-regulated kinase (ERK) attenuated GCE-induced transcriptional activity and protein synthesis. In addition, through aprotinin treatment and PAR2 small interfering RNA transfection, it was proven that protease of GCE is consistent with the regulation of GCE-induced IL-8.

CONCLUSION

We conclude that GCE with protease activity-induced IL-8 expression is regulated by transcriptional activation of NF-kappaB and NF-IL6 coordinating with the ERK pathway in human airway epithelial cells.

Allergenicity of recombinant Bla g 7, German cockroach tropomyosin

BACKGROUND

Cockroach infestation may sensitize and elicit allergic responses to genetically predisposed individuals. Invertebrate tropomyosins are a frequent cause of allergy and highly cross-reactive in nature. In this study, we aimed to produce recombinant German cockroach tropomyosin and investigate its allergenicity.

METHODS

German cockroach tropomyosin (Bla g 7) was cloned by reverse transcriptase polymerase chain reaction (RT-PCR). The cloned cDNA was over-expressed in Escherichia coli and purified by affinity chromatography using Ni-nitrilotriacetic (NTA) acid resin. The allergenicity of the recombinant tropomyosin was examined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The cloned Bla g 7 shared up to 91% amino acid sequence identity with other cockroach tropomyosins. ELISA showed a recombinant Bla g 7 sensitization rate of 16.2% to German cockroach allergic sera. Recombinant tropomyosin was able to inhibit 32.4% of the specific IgE binding to cockroach extract.

CONCLUSIONS

Tropomyosin represents a minor allergen in cockroach extracts. It is hoped that recombinant tropomyosin will be useful for further studies and clinical applications.

Localization of Der f 2 in the gut and fecal pellets of Dermatophagoides farinae

BACKGROUND

House dust mite derived materials are known to be the most potent agent inducing allergic diseases. Localization of Der f 2 was attempted to specify the sites and concentrations of Der f 2 within the mite, which may indicate the importance of secreted materials and nonexcreted body components as allergen sources.

METHODS

Serial cryostat sections of embedded live mites and the fecal pellets, collected by brush, were immunoprobed using monoclonal antibody (mAb) 2F38 raised against recombinant (r) Der f 2.

RESULTS

Highest concentrations were found in the anterior midgut, implying that this is the site of Der f 2 synthesis and secretion. Digestive material and defecated fecal pellets were also labeled with mAb.

CONCLUSIONS

Our results show that the major allergen, Der f 2, found in the house dust mite D. farinae is derived from the digestive tract, and is concentrated in the feces.

Monoclonal antibodies to recombinant Der f 2 and development of a two-site ELISA sensitive to major Der f 2 isoallergen in Korea

BACKGROUND

Der f 2 is a major sensitizing allergen in patients allergic to house dust mites worldwide. Isoforms of Der f 2 have been reported and are known to have different antigenicities. The aim of this study was to facilitate antigenic analysis and to develop an improved method for the detection of Der f 2 isoallergen, which is prevalent in Korea.

METHODS

A two-site ELISA was developed with monoclonal antibodies (mAbs) which were produced against recombinant Der f 2 (rDer f 2) and applied to assess Der f 2 in bedding samples.

RESULTS

A major isoform of Der f 2, found in Korea, was found to have amino acid variations especially at position 100 from lysine to glutamic acid, which is known to reduce significantly the binding affinity of mAbs when used to assess group 2 allergens. The detection limit of the developed two-site ELISA was determined to be about 8 ng/ml with rDer f 2 and 1 microg/ml with Derntatophagoides farinae crude extract. The average amount of Der f 2 in dust obtained from bedding samples from 89 homes in Seoul was estimated to be 25.61+/-10.70 microg/g dust.

CONCLUSIONS

Assays using mAbs for rDer f 2 could be useful for the assessment of environmental allergen exposure and mAbs could be used to further characterize the isoallergens of Der f 2.