Strategies for reducing the allergenicity of hen egg by treatment with natural antioxidants

Food allergies are caused by abnormal immune responses to food components (allergens), namely proteins. For this reason, eggs are one of the richest foods in the food chain and are therefore essential for a healthy diet. However, worldwide 6-9 % of the child population and 4 % of adults are allergic to eggs, which prevent their consumption or any derived products. Hen’s egg allergy has increased worldwide due to the ubiquitous of eggs in the diet. Ovalbumin (OVA) is the most abundant protein in the egg white and causes allergy, especially in children and young children, being one of the most common food allergies, mediated by IgE. Until now, the processes used to decrease the allergenicity of egg proteins, such as cooking, thermal processing, and enzymatic digestion have not been totally effective, because the allergens have high stability and resistance. Thus, there are no drugs to prevent allergic reactions, and avoiding the egg has been the only way to prevent this allergy. Phenolic compounds (PC) are recognized as having a potent antioxidant, anti-inflammatory, antibacterial, antiviral and antitumor activity. In addition, these compounds, present in fruits and vegetables, can bind to peptides and proteins to form complexes, being able to promote alteration of its native conformation and to contribute to the reduction of allergenicity. Therefore, the goal of this work was the development of a process to reduce the allergenicity of hen egg proteins through the action of natural antioxidants, such as PC, under different experimental conditions, in order to promote alterations of proteins native structure, and concomitantly, of its allergenic capacity. Spectroscopic techniques have stood out among the various methods, as they use small amounts of sample, do not cause damage of the sample and can be used in different experimental conditions to analyse the conformational changes that can occur during the chemical, physical and enzymatic modifications of proteins. Thus, the OVA changes promoted by the different PC were evaluated using techniques such as circular dichroism (CD), fluorescence and total attenuated reflection - infrared Fourier transform (ATR-FTIR). The OVA solutions were incubated at different temperatures, with different PC (gallic, caffeic, ferulic, chlorogenic and tannic acids, resveratrol and quercetin) prepared with the same buffer solution. The results showed that the structure of OVA was affected by the binding of these compounds. The fluorescence spectra demonstrated that the PC quenched the fluorescent amino acid tryptophan, which means that the interactions occurred directly or close to this amino acid residue. It was also observed that the fluorescence of OVA solutions decreased with increasing PC concentration. The quenching mechanism calculated from the Stern-Volmer constant (KSV) and the bimolecular quenching constant (Kq) suggests a static quenching mechanism. However, when considering the effect of temperature variation (298.15 to 318.15 K and 318.15 to 328.15 K) on fluorescence quenching, it was found that KSV and Kq decreased with the increase of temperature in some OVA-PC complexes, leading to a dynamic extinction mechanism. On the other hand, for other complexes, KSV and Kq increased with increasing temperature, or remained constant, suggesting, respectively, a static extinction mechanism and a mixed extinction mechanism (static and dynamic). The same effect was observed for the binding constant Kb, with temperature change. Furthermore, the thermodynamic analysis, according to the values found for ΔH and ΔS for all OVA-PC complexes tested, at both temperatures, suggested that the reactions occurred spontaneously (ΔG<0) with the participation of weak interactions, namely hydrophobic interactions and hydrogen. The experiments with CD and ATR-FTIR showed changes in the secondary structure of OVA, originated by the conversion of the α-helix into β- sheets. Molecular docking showed that the PC can interact directly with OVA epitopes or in its neighborhood, preventing IgE binding. Therefore, the application of natural antioxidants, such as PC, in the treatment of egg proteins appears to be a potential alternative to the current methods used in reducing the allergenicity of egg proteins. In fact, all PC bound to OVA, changing its secondary and tertiary structure. As future perspectives, in-depth studies will be carried out with the whole egg treated with selected PC, to evaluate the binding of the specific IgE, as a strategy to reduce allergy to eggs and to produce hypoallergenic eggs. The confirmation of the decrease of allergenicity will be carried out by immunoblotting and ELISA tests with sera from patients allergic to egg and comparing the levels of specific IgE that binds to treated and untreated OVA with PC. Subsequently, the reduction/elimination of allergenicity in vivo will be evaluated by skin prick tests in allergic patients using OVA and whole egg extracts, treated with PC. It is expected to produce an egg-derived product that allows the egg-allergic population to consume it.As alergias alimentares são causadas por respostas imunológicas anormais a componentes dos alimentos, nomeadamente proteínas (alergénios). Por esta razão, os ovos são um dos alimentos mais ricos da cadeia alimentar, sendo deste modo essenciais numa alimentação saudável. Contudo, a nível mundial cerca de 6-9 % da população infantil, e 4 % dos adultos, é alérgica aos ovos, o que impede o seu consumo ou de qualquer produto derivado. A alergia ao ovo de galinha tem aumentado em todo o mundo devido à omnipresença dos ovos na dieta, sendo uma das alergias alimentares mais comuns mediada por imunoglobulina E (IgE). A ovalbumina (OVA) é a proteína que existe em maior abundância na clara do ovo e a principal causa de alergia ao ovo em crianças e adolescentes. Até ao momento, os processos utilizados para a diminuição da alergenicidade das proteínas do ovo, como o tratamento térmico e digestão enzimática, entre outros, não têm sido totalmente eficazes, porque alguns alergénios apresentam elevada estabilidade e resistência. Assim, não existem ainda soluções industriais totalmente eficazes, nem medicamentos para a prevenção das reações alérgicas ao ovo, pelo que a sua evicção tem sido a única maneira de prevenir a alergia. Os compostos fenólicos são reconhecidos como possuindo variadas atividades biológicas, como por exemplo: antioxidante; anti-inflamatória; antibacteriana; antiviral e antitumoral. Além disso, estes compostos, presentes na fruta e vegetais, ligam-se a péptidos e proteínas para formar complexos, podendo promover alteração da sua conformação nativa e, contribuir para a diminuição da alergenicidade. Assim, o objetivo deste trabalho foi desenvolver um processo para diminuição da alergenicidade das proteínas do ovo, nomeadamente da OVA, através da ação dos compostos fenólicos, em diferentes condições experimentais, de modo a promover alteração da sua estrutura nativa, e concomitantemente, da sua capacidade alergénica. As técnicas espectroscópicas têm-se destacado pelo facto de necessitarem de pequenas quantidades de amostra, não serem destrutivas e poderem ser utilizadas sob diferentes condições experimentais. Deste modo, as principais alterações na estrutura proteica foram avaliadas através de dicroísmo circular (CD), fluorescência e espectroscopia de infravermelho com transformada de Fourier e reflexão total atenuada (ATR-FTIR). Como modelo, soluções de OVA em tampão fosfato 0.05 M, pH 7.40, foram incubadas a diferentes temperaturas, com vários compostos fenólicos (ácidos: gálico; cafeico; ferúlico; clorogénico e tânico; resveratrol e quercetina) preparados com a mesma solução tampão. Os resultados demonstraram que a estrutura da OVA foi afetada pela ligação dos compostos fenólicos. Os espectros de fluorescência mostraram que os compostos fenólicos provocaram a extinção da fluorescência dos resíduos de triptofano da OVA, o que significa que as interações ocorreram diretamente ou próximo desses resíduos. A fluorescência das soluções de OVA diminuiu com o aumento da concentração dos compostos fenólicos. O mecanismo de quenching calculado a partir da constante de Stern-Volmer (KSV) e da constante de quenching bimolecular, sugere um mecanismo de quenching estático. No entanto, ao considerar-se o efeito da variação da temperatura (298,15 a 318,15 K e 318,15 a 328,15 K) na extinção de fluorescência, verificou-se que KSV e Kq diminuíram quando a temperatura aumentou para alguns complexos OVA-compostos fenólicos, levando a um mecanismo de extinção dinâmico. Por outro lado, para outros complexos, KSV e Kq aumentaram com o aumento da temperatura, ou mantiveram-se constantes, sugerindo, respectivamente, um mecanismo de extinção estático e um mecanismo de extinção misto (estático e dinâmico). O mesmo efeito foi observado para a constante de ligação Kb, com mudança de temperatura. Além disso, a análise termodinâmica, de acordo com os valores encontrados de ΔH e ΔS para todos os complexos de OVA com compostos fenólicos testados, em ambas as temperaturas, sugeriu que as reações ocorreram espontaneamente (ΔG<0) com a participação de interações fracas, principalmente hidrofóbica e pontes de hidrogénio. As experiências com CD e ATR-FTIR indicaram alterações na estrutura secundária da OVA, originadas principalmente pela conversão das hélices α em folhas β. O docking molecular mostrou que os compostos fenólicos testados podem interagir diretamente com os epítopos da OVA ou na sua proximidade, evitando presumivelmente a ligação de IgE. Em conclusão, todos os compostos fenólicos ligaram à OVA, alterando a sua estrutura terciária e secundária, sugerindo, deste modo, a aplicação destes antioxidantes naturais no tratamento das proteínas do ovo, como potencial alternativa para diminuir a sua alergenicidade. Como perspetivas futuras, deverão ser realizados estudos com o ovo completo a que os compostos fenólicos selecionados serão adicionados, para avaliar a ligação da IgEespecífica, pondo em prática a aplicação destes compostos como uma estratégia para redução da alergia aos ovos e produção de derivados de ovo hipoalergénicos. A confirmação da diminuição da alergenicidade, será realizada através de immunoblotting e ELISA com soros de doentes alérgicos ao ovo e comparando os níveis de IgE específica que se liga à OVA tratada e não tratada com compostos fenólicos. Posteriormente, a redução/eliminação da alergenicidade in vivo será avaliada por meio de testes de picada na pele em doentes alérgicos, utilizando extractos de OVA e de ovo inteiro, tratados com compostos fenólicos. Espera-se produzir um produto derivado do ovo que permite à população alérgica ao ovo, o seu consumo..University of Beira Interior, FEDER funds through the POCI - COMPETE 2020 - Operational Programme Competitiveness; Internationalization in Axis I - Strengthening research, technological development, and innovation (Project POCI-01-0145-FEDER-007491); National Funds by FCT - Foundation for Science and Technology (Project UID/Multi /00709/2013), who supported this work

Heterostructures in GaInP grown using a change in V/III ratio

Journal ArticleA natural monolayer 111% superlattice -- the CuPt ordered structure -- is formed spontaneously during organometallic vapor phase epitaxial OMVPE growth of Ga0.52In0.48P. The extent of this ordering process is found to be a strong function of the input partial pressure of the phosphorus precursor during growth due to the effect of this parameter on the surface reconstruction and step structure. Thus, heterostructures can be produced by simply changing the flow rate of the P precursor during growth. It is found, by examination of transmission electron microscope ~TEM! and atomic force microscope AFM images, and the photoluminescence PL and PL excitation PLE spectra, that order/disorder O/D really less ordered on more ordered heterostructures formed by decreasing the partial pressure of the P precursor during the OMVPE growth cycle at a temperature of 620 °C are graded over several thousands of Å when PH3 is the precursor. The ordered structure from the lower layer persists into the upper layer. Similarly, D/O structures produced by increasing the PH3 flow rate yield PL spectra also indicative of a graded composition at the heterostructure. The grading is not reduced by a 1 h interruption in the growth cycle at the interface. Similar heterostructures produced at 670 °C using tertiarybutylphosphine TBP as the P precursor show a totally different behavior. Abrupt D/O and O/D heterostructures can be produced by abruptly changing the TBP flowrate during the growth cycle. PL and PLE studies showdistinct peaks closely corresponding to those observed for the corresponding single layers. TEM dark field images also indicate that the interfaces in both for D/O and O/D heterostructures are abrupt. The cause of the difference in behavior for TBP and PH3 is not clear. It may be related to the difference in temperature

Ovalbumin Structural Changes by Phenolic Compounds Interactions

Ovalbumin (OVA) is the most prevalent protein in egg white and, represents the major allergen from avian egg white that causes IgE-mediated food allergic reactions particularly in children. It has been shown that phenolic compounds interact with proteins by a single or multipoint mechanism, promoting structural and functional changes. Moreover, the interaction of some allergens with polyphenols, led to permanent modification of the tertiary structure of the allergen, which can result in a reduction in its IgE-binding capacity. This work aimed to analyse the effect of phenolic compounds (Gallic, Caffeic, Ferulic, Chlorogenic and Tannic Acids, Resveratrol and Quercetin) on the native structure of OVA, using Circular Dichroism (CD), fluorescence and Fourier transform infrared spectroscopy (FTIR). The phenolic compounds were incubated with OVA at different times, concentrations and temperatures. Changes in OVA secondary and tertiary structures were increasingly induced with increasing temperatures by the phenolic compound. Also, for a constant temperature, the changes found in OVA structure increased with the phenolic compounds concentration. The results show that the interactions between phenolic compounds and OVA result in complexes (phenolics – OVA) where OVA native structure is changed. This is likely to affect epitopes and hence OVA allergenicity.N/

Interactions of Phenolic Compounds with Ovalbumin

Ovalbumin (OVA) is the major protein in egg white and can cause allergy mainly in infants and young children [1]. Egg allergy is an IgE mediated reaction and is one the most common food allergies. So far, the avoidance of the egg has been the unique way to prevent this allergy [2]. It is well known that phenolic compounds can bind to proteins promoting structural and functional changes. In this work, the interactions between OVA and the phenolic compounds were studied through spectroscopic techniques (fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR)) and docking. OVA solutions were incubated at different temperatures and times, with different phenolic compounds prepared with the same buffer solution (Gallic, Caffeic, Ferulic, Chlorogenic and Tannic Acids, Resveratrol and Quercetin). Results indicate that OVA's structure was affected by the binding of phenolic compounds. CD and FTIR experiments showed changes in the secondary structure of OVA, originated by the conversion of α-helix into β-sheets [1]. Fluorescence spectra demonstrated that phenolics are quenchers of fluorescent aminoacids (Tyrosine, Phenylalanine and Tryptophan) meaning that interactions occur directly or near these aminoacids. Fluorescence results also suggest that these interactions are electrostatic and thermodynamically favorable (∆G<0). Docking studies showed that the tested phenolic compounds can interact directly with OVA epitopes, or with its neighbors, thus avoiding the IgE binding. Therefore, the phenolic compounds can be used as a strategy for reducing egg allergy in foods.info:eu-repo/semantics/publishedVersio

Phenolic compounds: a novel approach to reduce egg allergenicity?

Hen's egg allergy has been climbing in all countries due to eggs ubiquity in foodstuffs. This allergy is an IgE mediated reaction that affects mainly infants and young children. So far, the processes used to decrease the allergenicity of egg proteins, such as cooking, thermal processing, storage and enzymatic digestion have not been totally effective. Previous studies demonstrated that proteins form complexes with phenolic compounds, so the aim of this work was to analyze the effect of these compounds in ovalbumin (OVA) conformation and its possible application to reduce eggs allergenicity. OVA was incubated at different temperatures with phenolic compounds (caffeic, chlorogenic, ferulic, gallic and tannic acids; resveratrol and quercetin) and was analyzed by circular dichroism (CD), Attenuated Total Reflection–Fourier Transform Infra-Red (ATRFTIR) spectroscopy and fluorescence. Changes in the secondary structure of OVA were evidenced by CD and ATR-FTIR. Also, protein fluorescence decreased with increasing concentrations of phenolic compounds. The thermodynamic analysis suggested that electrostatic interactions are important in the binding process, and the quenching mechanism occur by contact. This was confirmed by docking where the phenolic compounds bind specifically to some regions of the protein, including those with the allergenic epitopes.info:eu-repo/semantics/publishedVersio

Filipino physician-turned nurses: A phenomenological study

Foreign nurses have augmented the United States nursing workforce. The Philippines has remained the world\u27s leading exporter of nurses, including the United States. More recently, a new phenomenon has emerged involving Filipino physicians who went back to school to take up nursing in the Philippines in order to migrate to foreign countries to work as nurses. The purpose of this study was to describe and to interpret the lived experiences of Filipino physician-turned nurses in the United States. Phenomenology was used as research design, with data obtained from a purposive sample of eight (8) self-identified physician-turned nurses in Las Vegas, Nevada. Participants were interviewed using a single, open-ended central question. The audio taped responses that described their lived experiences were eventually transcribed verbatim. To interpret their experiences, clusters of themes were then generated using the Colaizzi\u27s (1978) method of Phenomenological Inquiry. The results of the study revealed that the experiences of Filipino physician-turned nurses involved multidimensional issues, both in the contexts of emigration and a professional shift from physician to nurse. Being the first of its kind, this study will enlighten society of the lived experiences of Filipino physicians who compromise professional integrity by working as nurses just to emigrate to the United States. Furthermore, this research study will contribute to the existing literature on cross-cultural adaptation, particularly involving role compromise in an unfamiliar social and cultural context

Microcrédito enquanto uma inovação social em Angola

Dissertação de mestrado em Economia SocialO presente estudo procurou analisar o desempenho do microcrédito em Angola através de uma estruturação de três secções, onde a primeira serviu de guião deste trabalho através da esquematização da introdução, englobando todos os seus acessórios. A segunda secção procurou explorar a revisão da literatura sobre os bancos sociais/microcréditos, apontando como uma das grandes diferen ciações entre a inovação convencional e inovação social, o seu objetivo ou finalidade, porém não descartando a convergência que possa existir na sua atuação para o bem comum. Ainda nesta secção é demonstrada o quanto esta medida foi crucial em períodos distintos, porém apresentou-se o exem plo de Raiffeisen na Alemanha com a associação do Pão e do economista Yunus em Bangladesh com o Grameen Bank. Na última secção é apresentado o esquema funcional do microcré dito em Angola, onde foi observado a sua institucionalização legal, sua pouca evidência de existência na base de dados Web of Science no período de 1900 a 2023, não sendo possível observar algum conteúdo sobre o mi crocrédito da realidade angolana. Ainda nesta secção é apresentado o re sultado do questionário, na qual é possível observar que ainda existem pou cas informações sobre este tema, o que de alguma coisa possa estar na origem da pouca perceção sobre o tema, e ainda também é observado que há poucas evidências para afirmar que não existe dependência de conheci mento do microcrédito e seus beneficiários.The present study sought to analyze the performance of microcredit in Angola through a structuring of three sections, where the first served as a guide of this work through the schematization of the introduction, encom passing all its accessories. The second section sought to explore the literature review on social banks/microcredits, pointing out one of the great differences between con ventional innovation and social innovation, its objective or purpose, but not discarding the convergence that may exist in its performance for the com mon good. Still, in this section, it is demonstrated how crucial this measure was in different periods, but the example of Raiffeisen in Germany with the association of Bread and the economist was presented Yunus in Bangla desh with Grameen Bank. The last section is presented the functional scheme of microcredit in Angola, where it was observed its legal institutionalization, is little evidence of existence in the Web of Science database in the period from 1900 to 2023, not possible to observe some content about the microcredit of the Angolan reality. Also in this section presented the results of the question naire, in which it is possible to observe that there is still little information about this theme, which may be the origin of the little perception of the subject, and it is also observed that there is little evidence to affirm that there is no dependence on knowledge of microcredit and its beneficiaries

Water Vapor Protocol

The purpose of this activity is to measure the total precipitable water vapor (column water vapor) in the atmosphere above an observer's site. Students point a GLOBE/GIFTS water vapor instrument at the sun and record the voltage readings from a digital voltmeter. They observe sky conditions near the Sun and perform the Cloud Protocols. Intended outcomes are that students understand the concept that the atmosphere prevents some of the sun's light from reaching Earth's surface, how water vapor measurements relate to the hydrologic cycle, and how greenhouse gases, such as water vapor, play an important role in weather and climate. Supporting background materials for both student and teacher are included. Educational levels: Middle school, High school