RESUMEN
Tip-enhanced Rayleigh scattering images of Ge quantum dots grown on a Si substrate have been observed at room temperature. Changing the wavelength of the incidence light from 405 to 590 nm, the contrast of the images is reversed. It is found that the scattering intensity depends on the dielectric constants of the materials under the probe. By changing the wavelength of the incident light, we have obtained information about the dielectric constant dispersion of single Ge quantum dots. The spectral peak position of single Ge quantum dots is found to shift to higher energy, compared to that of bulk Ge. Tip-enhanced photoluminescence from an In0.25Ga0.75N film at room temperature has also been reported. The strong local enhancement of the photoluminescence of the localized excitons has been observed in the vicinity of a gold nano-particle attached to the end of the probe. A coupling to plasmons in the gold nano-particle yields strong enhancement of the photoluminescence.
RESUMEN
It has generally been thought that iodine allergy is cross-sensitive to various iodine-containing chemicals. However, this concept seems to deviate from the immunological principle that immune recognition is specific. To solve this contradiction, we hypothesize that iodine allergy is an immunological reaction to iodinated autologous proteins produced in vivo by iodination reaction from various iodine-containing chemicals. Antisera to iodine were obtained from guinea pigs immunized subcutaneously with iodine-potassium iodide solution emulsified in complete Freund's adjuvant (CFA). The specificity of guinea pig anti-iodine antiserum was determined by enzyme-linked immunosorbent assay (ELISA) inhibition experiments using microplates coated with iodinated guinea pig serum albumin (I-GSA). Antibody activities were inhibited by I-GSA, diiodo-L-tyrosine, and thyroxine, but not by potassium iodide, monoiodo-L-tyrosine, 3,5,3'-triiodothyronine, monoiodo-L-histidine, or diiodo-L-histidine, or by ionic or non-ionic iodinated contrast media. The results that antigen recognition of anti-iodine antibody is specific to iodinated protein support our hypothesis. While protein iodination usually takes place both at histidine residues as well as at tyrosine residues, only iodinated tyrosine acted as an antigenic determinant and no antibody activities to iodinated histidine were detected in our experimental iodine allergy model.
Asunto(s)
Reacciones Antígeno-Anticuerpo/inmunología , Antígenos/inmunología , Epítopos/inmunología , Hipersensibilidad/inmunología , Yoduro de Potasio/inmunología , Animales , Especificidad de Anticuerpos , Antígenos/análisis , Sitios de Unión de Anticuerpos , Reacciones Cruzadas , Diyodotirosina/efectos adversos , Diyodotirosina/inmunología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta Inmunológica , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Adyuvante de Freund , Cobayas , Yoduro de Potasio/efectos adversos , Albúmina Sérica/inmunología , Tiroxina/efectos adversos , Tiroxina/inmunologíaRESUMEN
We hypothesize that iodine allergy is an immune response to iodinated autologous proteins generated in vivo from iodine-containing organic and inorganic chemicals. In this report, effects of protein iodination on elicitogenic activity in guinea pig iodine allergy model and iodinated protein antigen generation in vitro from iodine-containing chemicals were investigated. Active cutaneous anaphylaxis (ACA) and delayed-type hypersensitivity (DTH) tests were performed in guinea pigs immunized with iodine. The amount of iodine (I2) reacted to proteins for giving them an eliciting activity of ACA was > or = 0.15 micromol for 1 mg of albumin. DTH reactions were provoked by intradermal injection of 10(6) PECs reacted with > or = 0.075 micromol of I2. I2 was generated from a potassium iodide (KI) solution or iodinated contrast media by UV light irradiation. X-ray irradiation of KI and iodinated contrast media in the presence of protein resulted in the generation of iodinated protein antigens. The generation of iodinated protein antigens was inhibited in the presence of reducing agents. Therefore, it is noteworthy that iodine allergy of the present hypothesis is dependent on reactive oxygens. By presenting these ex vivo and in vitro data, we discuss the possibilities for the generation of iodinated protein antigens in vivo.
Asunto(s)
Medios de Contraste , Hipersensibilidad a las Drogas/etiología , Inmunización , Yodoproteínas/inmunología , Yoduro de Potasio , Traslado Adoptivo , Albúminas/química , Animales , Antígenos/inmunología , Antioxidantes/farmacología , Líquido Ascítico/citología , Líquido Ascítico/inmunología , Líquido Ascítico/metabolismo , Medios de Contraste/efectos adversos , Medios de Contraste/química , Medios de Contraste/efectos de la radiación , Modelos Animales de Enfermedad , Relación Dosis-Respuesta en la Radiación , Ensayo de Inmunoadsorción Enzimática , Femenino , Cobayas , Hipersensibilidad Tardía/inmunología , Yodoproteínas/síntesis química , Yodoproteínas/farmacología , Yohexol/efectos adversos , Yohexol/química , Yohexol/efectos de la radiación , Ácido Yotalámico/efectos adversos , Ácido Yotalámico/química , Ácido Yotalámico/efectos de la radiación , Anafilaxis Cutánea Pasiva/efectos de los fármacos , Anafilaxis Cutánea Pasiva/inmunología , Yoduro de Potasio/efectos adversos , Yoduro de Potasio/inmunología , Yoduro de Potasio/efectos de la radiación , Rayos Ultravioleta , Rayos XRESUMEN
We hypothesize that iodine allergy is an immune response to iodinated self proteins produced in vivo from various iodine-containing chemicals. Since an antigenic determinant of experimental iodine allergy is diiodotyrosine (DIT), we designed low molecular weight DIT derivatives having provocative antigenicity without sensitizing immunogenicity. Tetraiododityrosine and hexaiodotrityrosine provoked dose-dependent skin reactions in guinea pigs previously immunized with iodine. No guinea pigs immunized with hexaiodotrityrosine showed anaphylactic reaction by i.v. challenge with hexaiodotrityrosine and none of their antisera showed positive passive cutaneous anaphylaxis (PCA) reaction in guinea pigs, indicating the non-immunogenic nature of the compound. Erythrosine, one of the color additives having a structure common with DIT, was assessed for its immunological property. Enzyme-linked immunosorbent assay (ELISA) inhibition studies on erythrosine revealed that the inhibitory activity of erythrosine was stronger than that of DIT. Furthermore, erythrosine provoked a PCA reaction in animals sensitized with anti-iodine antisera. In conclusion, hexaiodotrityrosine is thought to be useful for skin testing of iodine allergy without any fear of sensitization to the allergen. Erythrosine was shown to provoke an experimental iodine allergy and, also, the relationships between the new concept of iodine allergy and features of clinical findings of adverse effects by iodocontrast media are discussed.