The effects of imidacloprid combined with endosulfan on IgE-mediated mouse bone marrow-derived mast cell degranulation and anaphylaxis.

Low levels of endosulfan are known to stimulate mast cells to release allergic mediators, while imidacloprid can inhibit IgE-mediated mast cell degranulation. However, little information about the effects of both pesticides together on mast cell degranulation is available. To measure the effects, IgE-activated mouse bone marrow-derived mast cells (BMMCs) were treated with imidacloprid and endosulfan, individually, and simultaneously at equi-molar concentrations in tenfold steps ranging from 10-4 to 10-11 M, followed by measuring several allergy-related parameters expressed in BMMCs: the mediator production and influx of Ca2+, the phosphorylation content of NF-κB in the FcεRI signaling pathway. Then, the effects of the mixtures on IgE-induced passive systemic anaphylaxis (PSA) of BALB/c was detectded. This study clearly showed that the application of equi-molar mixtures of both pesticides with 10-4-10-5 M significantly inhibited the IgE-mediated mouse bone marrow-derived mast cells degranulation in vitro and 10-4 M of them decreased IgE-mediated PSA in vivo, as the application of imidacloprid at the same concentration alone did. Morever endosulfan alone had no remarkable stimulatory effects on any of the factors measured. In conclusion, simultaneous application of equi-molar concentrations of both pesticides generally showed highly similar responses compared to the responses to imidacloprid alone, suggesting that the effects of the mixture could be solely attributed to the effects of imidacloprid.

Tracking the behavior of Maillard browning in lysine/arginine-sugar model systems under high hydrostatic pressure.

BACKGROUND: High-pressure processing is gaining popularity in the food industry. However, its effect on the Maillard reaction during high-pressure-assisted pasteurization and sterilization is not well documented. This study aimed to investigate the effects of high hydrostatic pressure on the Maillard reaction during these processes using amino acid (lysine or arginine)-sugar (glucose or fructose) solution models. RESULTS: High pressure retarded the intermediate and final stages of the Maillard reaction in the lysine-sugar model. For the lysine-glucose model, the degradation rate of Amadori compounds was decelerated, while acceleration was observed in the arginine-sugar model. Increased temperature not only accelerated the Maillard reaction over time but also formed fluorescent compounds with different emission wavelengths. Lysine reacted with the sugars more readily than arginine under the same conditions. In addition, it was easier for lysine to react with glucose, whereas arginine reacted more readily with fructose under high pressure. CONCLUSION: High pressure exerts different effects on lysine-sugar and arginine-sugar models. © 2017 Society of Chemical Industry.

Combined effect of glycation and sodium carbonate-bicarbonate buffer concentration on IgG binding, IgE binding and conformation of ovalbumin.

BACKGROUND: Ovalbumin (OVA) is a major allergen in hen egg. During thermal processing, reducing sugars contained in the hen egg white might easily undergo glycation with OVA, but few studies have been conducted on its corresponding immunoreactivity changes. The aim of the present study was to assess changes of the antigenicity, potential allergenicity and conformation of OVA after glycation in a wet-thermal processing system under different concentrations of sodium carbonate-bicarbonate buffer. RESULTS: IgE binding of the glycated OVA was increased after glycation, and the higher the sodium carbonate-bicarbonate buffer concentration, the higher the IgE binding capacity. The increase in IgE binding of OVA corresponded well with the disruption of the disulfide bond, which exposed the epitopes initially buried. Antigenicity of the glycated OVA was increased, and the amount of the increase varied among samples treated under different buffer concentrations. CONCLUSION: Glycation increased the allergenic potential for OVA, with the amount of increase varying with different sodium carbonate-bicarbonate buffer concentrations.

High-pressure microfluidisation-induced changes in the antigenicity and conformation of allergen Ara h 2 purified from Chinese peanut.

BACKGROUND: Peanut allergy is one of the most serious food allergies, and Ara h 2 is one of the most important peanut allergens as it is recognised by serum immunoglobulin E from more than 90% of peanut-allergic individuals. Dynamic high-pressure microfluidisation has been widely used in food processing as a new technology. The aim of this study was to investigate the effect of high-pressure microfluidisation on the antigenicity and structure of Ara h 2. Extracted peanut allergen Ara h 2 was treated under a continuous pressure array of 60, 90, 120, 150 and 180 MPa. Immunoreactivity was measured by indirect enzyme-linked immunosorbent assay with rabbit polyclonal antibodies. Secondary structure was analysed by circular dichroism. Surface hydrophobicity and sulfhydryl groups were assessed via fluorescence and UV absorption spectra respectively. RESULTS: High-pressure microfluidisation treatment decreased the antigenicity of peanut allergen Ara h 2, changed its secondary structure and increased its UV absorption intensity and surface hydrophobicity. CONCLUSION: The change in conformation contributed to the decrease in antigenicity of Ara h 2, and the spatial conformation of peanut allergen Ara h 2 plays a critical role in its antigenicity.

[Effect of heat treatment on the antigenicity and conformation of peanut allergen Ara h 2].

Peanut allergen Ara h 2 was extracted from peanuts and was identified by SDS-PAGE and MALDI-TOF-MS. Effect of heat treatment on the antigenicity and structure of Ara h 2 was measured by indirect ELISA, CD, fluorescence and UV absorption spectra. The results showed that the antigenicity of Ara h 2 had a slight increase after being heated at 55 or 70 degrees C, while above 85 degrees C the antigenicity decreased significantly, and the antigeicity of Ara h 2 decreased with increasing temperature. The CD showed that the secondary structure of Ara h 2 was changed after heat treatment. The ANS fluorescence probe emission spectra analysis demonstrated that the heat treatment induced an increase in surface hydrophobicity of Ara h 2. The UV absorption spectra showed that the absorption maximum wavelength was increased when Ara h 2 was heated except the sample heating at 50 degrees C for 30 min. So the changes in conformation of Ara h 2 lead to the antigenicity degression.