Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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IgE Cross-Reactivity of Cashew Nut Allergens
Bastiaan-Net, Shanna ; Reitsma, Marit ; Cordewener, Jan H.G. ; Valk, Johanna P.M. van der; America, Twan A.H.P. ; Dubois, Anthony E.J. ; Gerth van Wijk, Roy ; Savelkoul, Huub F.J. ; Jong, Nicolette W. de; Wichers, Harry J. - \ 2019
International Archives of Allergy and Immunology 178 (2019)1. - ISSN 1018-2438 - p. 19 - 32.
Allergenicity - Cashew nut - Food allergy - IgE cross-reactivity - Immunoblotting - Tree nut allergy

Background: Allergic sensitisation towards cashew nut often happens without a clear history of eating cashew nut. IgE cross-reactivity between cashew and pistachio nut is well described; however, the ability of cashew nut-specific IgE to cross-react to common tree nut species and other Anacardiaceae, like mango, pink peppercorn, or sumac is largely unknown. Objectives: Cashew nut allergic individuals may cross-react to foods that are phylogenetically related to cashew. We aimed to determine IgE cross-sensitisation and cross-reactivity profiles in cashew nut-sensitised subjects, towards botanically related proteins of other Anacardiaceae family members and related tree nut species. Method: Sera from children with a suspected cashew nut allergy (n = 56) were assessed for IgE sensitisation to common tree nuts, mango, pink peppercorn, and sumac using dot blot technique. Allergen cross-reactivity patterns between Anacardiaceae species were subsequently examined by SDS-PAGE and immunoblot inhibition, and IgE-reactive allergens were identified by LC-MS/MS. Results: From the 56 subjects analysed, 36 were positive on dot blot for cashew nut (63%). Of these, 50% were mono-sensitised to cashew nuts, 19% were co-sensitised to Anacardiaceae species, and 31% were co-sensitised to tree nuts. Subjects co-sensitised to Anacardiaceae species displayed a different allergen recognition pattern than subjects sensitised to common tree nuts. In pink peppercorn, putative albumin- and legumin-type seed storage proteins were found to cross-react with serum of cashew nut-sensitised subjects in vitro. In addition, a putative luminal binding protein was identified, which, among others, may be involved in cross-reactivity between several Anacardiaceae species. Conclusions: Results demonstrate the in vitro presence of IgE cross-sensitisation in children towards multiple Anacardiaceae species. In this study, putative novel allergens were identified in cashew, pistachio, and pink peppercorn, which may pose factors that underlie the observed cross-sensitivity to these species. The clinical relevance of this widespread cross-sensitisation is unknown.

The burden of cardiovascular diseases among us states, 1990-2016
Roth, Gregory A. ; Johnson, Catherine O. ; Abate, Kalkidan Hassen ; Abd-Allah, Foad ; Ahmed, Muktar ; Alam, Khurshid ; Alam, Tahiya ; Alvis-Guzman, Nelson ; Ansari, Hossein ; Ärnlöv, Johan ; Atey, Tesfay Mehari ; Awasthi, Ashish ; Awoke, Tadesse ; Barac, Aleksandra ; Bärnighausen, Till ; Bedi, Neeraj ; Bennett, Derrick ; Bensenor, Isabela ; Biadgilign, Sibhatu ; Castañeda-Orjuela, Carlos ; Catalá-López, Ferrán ; Davletov, Kairat ; Dharmaratne, Samath ; Ding, Eric L. ; Dubey, Manisha ; Faraon, Emerito Jose Aquino ; Farid, Talha ; Farvid, Maryam S. ; Feigin, Valery ; Fernandes, João ; Frostad, Joseph ; Gebru, Alemseged ; Geleijnse, Johanna M. ; Gona, Philimon Nyakauru ; Griswold, Max ; Hailu, Gessessew Bugssa ; Hankey, Graeme J. ; Hassen, Hamid Yimam ; Havmoeller, Rasmus ; Hay, Simon ; Heckbert, Susan R. ; Irvine, Caleb Mackay Salpeter ; James, Spencer Lewis ; Jara, Dube ; Kasaeian, Amir ; Khan, Abdur Rahman ; Khera, Sahil ; Khoja, Abdullah T. ; Khubchandani, Jagdish ; Kim, Daniel ; Kolte, Dhaval ; Lal, Dharmesh ; Larsson, Anders ; Linn, Shai ; Lotufo, Paulo A. ; Razek, Hassan Magdy Abd El; Mazidi, Mohsen ; Meier, Toni ; Mendoza, Walter ; Mensah, George A. ; Meretoja, Atte ; Mezgebe, Haftay Berhane ; Mirrakhimov, Erkin ; Mohammed, Shafiu ; Moran, Andrew Edward ; Nguyen, Grant ; Nguyen, Minh ; Ong, Kanyin Liane ; Owolabi, Mayowa ; Pletcher, Martin ; Pourmalek, Farshad ; Purcell, Caroline A. ; Qorbani, Mostafa ; Rahman, Mahfuzar ; Rai, Rajesh Kumar ; Ram, Usha ; Reitsma, Marissa Bettay ; Renzaho, Andre M.N. ; Rios-Blancas, Maria Jesus ; Safiri, Saeid ; Salomon, Joshua A. ; Sartorius, Benn ; Sepanlou, Sadaf Ghajarieh ; Shaikh, Masood Ali ; Silva, Diego ; Stranges, Saverio ; Tabarés-Seisdedos, Rafael ; Atnafu, Niguse Tadele ; Thakur, J.S. ; Topor-Madry, Roman ; Truelsen, Thomas ; Tuzcu, E.M. ; Tyrovolas, Stefanos ; Ukwaja, Kingsley Nnanna ; Vasankari, Tommi ; Vlassov, Vasiliy ; Vollset, Stein Emil ; Wakayo, Tolassa ; Weintraub, Robert ; Wolfe, Charles ; Workicho, Abdulhalik ; Xu, Gelin ; Yadgir, Simon ; Yano, Yuichiro ; Yip, Paul ; Yonemoto, Naohiro ; Younis, Mustafa ; Yu, Chuanhua ; Zaidi, Zoubida ; Sayed Zaki, Maysaa El; Zipkin, Ben ; Afshin, Ashkan ; Gakidou, Emmanuela ; Lim, Stephen S. ; Mokdad, Ali H. ; Naghavi, Mohsen ; Vos, Theo ; Murray, Christopher J.L. - \ 2018
JAMA Cardiology 3 (2018)5. - ISSN 2380-6583 - p. 375 - 389.
Importance: Cardiovascular disease (CVD) is the leading cause of death in the United States, but regional variation within the United States is large. Comparable and consistent state-level measures of total CVD burden and risk factors have not been produced previously. Objective: To quantify and describe levels and trends of lost health due to CVD within the United States from 1990 to 2016 as well as risk factors driving these changes. Design, setting, and participants: Using the Global Burden of Disease methodology, cardiovascular disease mortality, nonfatal health outcomes, and associated risk factors were analyzed by age group, sex, and year from 1990 to 2016 for all residents in the United States using standardized approaches for data processing and statistical modeling. Burden of disease was estimated for 10 groupings of CVD, and comparative risk analysis was performed. Data were analyzed from August 2016 to July 2017. Exposures: Residing in the United States. Main outcomes ans measures: Cardiovascular disease disability-Adjusted life-years (DALYs). Results: Between 1990 and 2016, age-standardized CVD DALYs for all states decreased. Several states had large rises in their relative rank ordering for total CVD DALYs among states, including Arkansas, Oklahoma, Alabama, Kentucky, Missouri, Indiana, Kansas, Alaska, and Iowa. The rate of decline varied widely across states, and CVD burden increased for a small number of states in the most recent years. Cardiovascular disease DALYs remained twice as large among men compared with women. Ischemic heart disease was the leading cause of CVD DALYs in all states, but the second most common varied by state. Trends were driven by 12 groups of risk factors, with the largest attributable CVD burden due to dietary risk exposures followed by high systolic blood pressure, high body mass index, high total cholesterol level, high fasting plasma glucose level, tobacco smoking, and low levels of physical activity. Increases in risk-deleted CVD DALY rates between 2006 and 2016 in 16 states suggest additional unmeasured risks beyond these traditional factors. Conclusions and relevance: Large disparities in total burden of CVD persist between US states despite marked improvements in CVD burden. Differences in CVD burden are largely attributable to modifiable risk exposures.
Origin and Processing Methods Slightly Affect Allergenic Characteristics of Cashew Nuts (Anacardium occidentale)
Reitsma, Marit ; Bastiaan-Net, Shanna ; Sijbrandij, Lutske ; Weert, Evelien de; Sforza, Stefano ; Gerth van Wijk, Roy ; Savelkoul, Huub F.J. ; Jong, Nicolette W. de; Wichers, Harry J. - \ 2018
Journal of Food Science 83 (2018)4. - ISSN 0022-1147 - p. 1153 - 1164.
2D electrophoresis - Anacardium occidentale - cashew - in vitro gastric digestion
The protein content and allergen composition was studied of cashews from 8 different origins (Benin, Brazil, Ghana, India, Ivory Coast, Mozambique, Tanzania, Vietnam), subjected to different in-shell heat treatments (steamed, fried, drum-roasted). On 2D electrophoresis, 9 isoforms of Ana o 1, 29 isoforms of Ana o 2 (11 of the acidic subunit, 18 of the basic subunit), and 8 isoforms of the large subunit of Ana o 3 were tentatively identified. Based on 1D and 2D electrophoresis, no difference in allergen content (Ana o 1, 2, 3) was detected between the cashews of different origins (P > 0.5), some small but significant differences were detected in allergen solubility between differently heated cashews. No major differences in N- and C-terminal microheterogeneity of Ana o 3 were detected between cashews of different origins. Between the different heat treatments, no difference was detected in glycation, pepsin digestibility, or IgE binding of the cashew proteins.
Phylogenetic classification of the world's tropical forests
Slik, J.W.F. ; Franklin, Janet ; Arroyo-Rodríguez, Víctor ; Field, Richard ; Aguilar, Salomon ; Aguirre, Nikolay ; Ahumada, Jorge ; Aiba, Shin Ichiro ; Alves, Luciana F. ; Anitha, K. ; Avella, Andres ; Mora, Francisco ; Aymard, Gerardo A.C. ; Báez, Selene ; Balvanera, Patricia ; Bastian, Meredith L. ; Bastin, Jean François ; Bellingham, Peter J. ; Berg, Eduardo Van Den; Conceição Bispo, Polyanna Da; Boeckx, Pascal ; Boehning-Gaese, Katrin ; Bongers, Frans ; Boyle, Brad ; Brambach, Fabian ; Brearley, Francis Q. ; Brown, Sandra ; Chai, Shauna Lee ; Chazdon, Robin L. ; Chen, Shengbin ; Chhang, Phourin ; Chuyong, George ; Ewango, Corneille ; Coronado, Indiana M. ; Cristóbal-Azkarate, Jurgi ; Culmsee, Heike ; Damas, Kipiro ; Dattaraja, H.S. ; Davidar, Priya ; DeWalt, Saara J. ; Din, Hazimah ; Drake, Donald R. ; Duque, Alvaro ; Durigan, Giselda ; Eichhorn, Karl ; Eler, Eduardo Schmidt ; Enoki, Tsutomu ; Ensslin, Andreas ; Fandohan, Adandé Belarmain ; Farwig, Nina ; Feeley, Kenneth J. ; Fischer, Markus ; Forshed, Olle ; Garcia, Queila Souza ; Garkoti, Satish Chandra ; Gillespie, Thomas W. ; Gillet, Jean Francois ; Gonmadje, Christelle ; Granzow-De La Cerda, Iñigo ; Griffith, Daniel M. ; Grogan, James ; Hakeem, Khalid Rehman ; Harris, David J. ; Harrison, Rhett D. ; Hector, Andy ; Hemp, Andreas ; Homeier, Jürgen ; Hussain, M.S. ; Ibarra-Manríquez, Guillermo ; Hanum, I.F. ; Imai, Nobuo ; Jansen, Patrick A. ; Joly, Carlos Alfredo ; Joseph, Shijo ; Kartawinata, Kuswata ; Kearsley, Elizabeth ; Kelly, Daniel L. ; Kessler, Michael ; Killeen, Timothy J. ; Kooyman, Robert M. ; Laumonier, Yves ; Laurance, Susan G. ; Laurance, William F. ; Lawes, Michael J. ; Letcher, Susan G. ; Lindsell, Jeremy ; Lovett, Jon ; Lozada, Jose ; Lu, Xinghui ; Lykke, Anne Mette ; Mahmud, Khairil Bin; Mahayani, Ni Putu Diana ; Mansor, Asyraf ; Marshall, Andrew R. ; Martin, Emanuel H. ; Matos, Darley Calderado Leal ; Meave, Jorge A. ; Melo, Felipe P.L. ; Mendoza, Zhofre Huberto Aguirre ; Metali, Faizah ; Medjibe, Vincent P. ; Metzger, Jean Paul ; Metzker, Thiago ; Mohandass, D. ; Munguía-Rosas, Miguel A. ; Muñoz, Rodrigo ; Nurtjahy, Eddy ; Oliveira, Eddie Lenza De; Onrizal, ; Parolin, Pia ; Parren, Marc ; Parthasarathy, N. ; Paudel, Ekananda ; Perez, Rolando ; Pérez-García, Eduardo A. ; Pommer, Ulf ; Poorter, Lourens ; Qi, Lan ; Piedade, Maria Teresa F. ; Pinto, José Roberto Rodrigues ; Poulsen, Axel Dalberg ; Poulsen, John R. ; Powers, Jennifer S. ; Prasad, Rama Chandra ; Puyravaud, Jean Philippe ; Rangel, Orlando ; Reitsma, Jan ; Rocha, Diogo S.B. ; Rolim, Samir ; Rovero, Francesco ; Rozak, Andes ; Ruokolainen, Kalle ; Rutishauser, Ervan ; Rutten, Gemma ; Mohd Said, Mohd Nizam ; Saiter, Felipe Z. ; Saner, Philippe ; Santos, Braulio ; Santos, João Roberto Dos; Sarker, Swapan Kumar ; Schmitt, Christine B. ; Schoengart, Jochen ; Schulze, Mark ; Sheil, Douglas ; Sist, Plinio ; Souza, Alexandre F. ; Spironello, Wilson Roberto ; Sposito, Tereza ; Steinmetz, Robert ; Stevart, Tariq ; Suganuma, Marcio Seiji ; Sukri, Rahayu ; Sultana, Aisha ; Sukumar, Raman ; Sunderland, Terry ; Supriyadi, S. ; Suresh, H.S. ; Suzuki, Eizi ; Tabarelli, Marcelo ; Tang, Jianwei ; Tanner, Ed V.J. ; Targhetta, Natalia ; Theilade, Ida ; Thomas, Duncan ; Timberlake, Jonathan ; Morisson Valeriano, Márcio De; Valkenburg, Johan Van; Do, Tran Van; Sam, Hoang Van; Vandermeer, John H. ; Verbeeck, Hans ; Vetaas, Ole Reidar ; Adekunle, Victor ; Vieira, Simone A. ; Webb, Campbell O. ; Webb, Edward L. ; Whitfeld, Timothy ; Wich, Serge ; Williams, John ; Wiser, Susan ; Wittmann, Florian ; Yang, Xiaobo ; Yao, C.Y.A. ; Yap, Sandra L. ; Zahawi, Rakan A. ; Zakaria, Rahmad ; Zang, Runguo - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)8. - ISSN 0027-8424 - p. 1837 - 1842.
Biogeographic legacies - Forest classification - Forest functional similarity - Phylogenetic community distance - Tropical forests

Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northernhemisphere forests.

Field methods for sampling tree height for tropical forest biomass estimation
Sullivan, Martin J.P. ; Lewis, Simon L. ; Hubau, Wannes ; Qie, Lan ; Baker, Timothy R. ; Banin, Lindsay F. ; Chave, Jerôme ; Cuni-Sanchez, Aida ; Feldpausch, Ted R. ; Lopez-Gonzalez, Gabriela ; Arets, Eric ; Ashton, Peter ; Bastin, Jean François ; Berry, Nicholas J. ; Bogaert, Jan ; Boot, Rene ; Brearley, Francis Q. ; Brienen, Roel ; Burslem, David F.R.P. ; Canniere, Charles de; Chudomelová, Markéta ; Dančák, Martin ; Ewango, Corneille ; Hédl, Radim ; Lloyd, Jon ; Makana, Jean Remy ; Malhi, Yadvinder ; Marimon, Beatriz S. ; Junior, Ben Hur Marimon ; Metali, Faizah ; Moore, Sam ; Nagy, Laszlo ; Vargas, Percy Nuñez ; Pendry, Colin A. ; Ramírez-Angulo, Hirma ; Reitsma, Jan ; Rutishauser, Ervan ; Salim, Kamariah Abu ; Sonké, Bonaventure ; Sukri, Rahayu S. ; Sunderland, Terry ; Svátek, Martin ; Umunay, Peter M. ; Martinez, Rodolfo Vasquez ; Vernimmen, Ronald R.E. ; Torre, Emilio Vilanova ; Vleminckx, Jason ; Vos, Vincent ; Phillips, Oliver L. - \ 2018
Methods in Ecology and Evolution 9 (2018)5. - ISSN 2041-210X - p. 1179 - 1189.
Above-ground biomass estimation - Allometry - Carbon stocks - Forest inventory - Forest structure - Sample size
Quantifying the relationship between tree diameter and height is a key component of efforts to estimate biomass and carbon stocks in tropical forests. Although substantial site-to-site variation in height-diameter allometries has been documented, the time consuming nature of measuring all tree heights in an inventory plot means that most studies do not include height, or else use generic pan-tropical or regional allometric equations to estimate height. Using a pan-tropical dataset of 73 plots where at least 150 trees had in-field ground-based height measurements, we examined how the number of trees sampled affects the performance of locally derived height-diameter allometries, and evaluated the performance of different methods for sampling trees for height measurement. Using cross-validation, we found that allometries constructed with just 20 locally measured values could often predict tree height with lower error than regional or climate-based allometries (mean reduction in prediction error = 0.46 m). The predictive performance of locally derived allometries improved with sample size, but with diminishing returns in performance gains when more than 40 trees were sampled. Estimates of stand-level biomass produced using local allometries to estimate tree height show no over- or under-estimation bias when compared with biomass estimates using field measured heights. We evaluated five strategies to sample trees for height measurement, and found that sampling strategies that included measuring the heights of the ten largest diameter trees in a plot outperformed (in terms of resulting in local height-diameter models with low height prediction error) entirely random or diameter size-class stratified approaches. Our results indicate that even limited sampling of heights can be used to refine height-diameter allometries. We recommend aiming for a conservative threshold of sampling 50 trees per location for height measurement, and including the ten trees with the largest diameter in this sample.
Wild, insectivorous bats might be carriers of Campylobacter spp.
Hazeleger, Wilma C. ; Jacobs-Reitsma, Wilma F. ; Lina, Peter H.C. ; Boer, Albert G. De; Bosch, Thijs ; Hoek, Angela H.A.M. Van; Beumer, Rijkelt R. - \ 2018
PLoS ONE 13 (2018)1. - ISSN 1932-6203
Background The transmission cycles of the foodborne pathogens Campylobacter and Salmonella are not fully elucidated. Knowledge of these cycles may help reduce the transmission of these pathogens to humans. Methodology/principal findings The presence of campylobacters and salmonellas was examined in 631 fresh fecal samples of wild insectivorous bats using a specially developed method for the simultaneous isolation of low numbers of these pathogens in small-sized fecal samples ( 0.1 g). Salmonella was not detected in the feces samples, but thermotolerant campylobacters were confirmed in 3% (n = 17) of the bats examined and these pathogens were found in six different bat species, at different sites, in different ecosystems during the whole flying season of bats. Molecular typing of the 17 isolated strains indicated C. jejuni (n = 9), C. coli (n = 7) and C. lari (n = 1), including genotypes also found in humans, wildlife, environmental samples and poultry. Six strains showed unique sequence types. Conclusion/significance This study shows that insectivorous bats are not only carriers of viral pathogens, but they can also be relevant for the transmission of bacterial pathogens. Bats should be considered as carriers and potential transmitters of Campylobacter and, where possible, contact between bats (bat feces) and food or feed should be avoided.
Possibilities and opportunities for recoveryof nutrients other than phosphorus : An exploratory research
Kupfernagel, Juliane ; Reitsma, Berend ; Steketee, Jaap ; Ruijter, Frank de; Blom, Johan - \ 2017
Deventer : Tauw - 81
Campylobacter spp. strain choice and food matrix strongly affect LDO50 results
Hazeleger, W.C. ; Jongenburger, I. ; Jacobs-Reitsma, W.F. ; Besten, H.M.W. den - \ 2017
Introduction: Campylobacteriosis is the most comm-only reported zoonosis in the EU and the occurrence of Campylobacter in broiler meat remains high. The detection in food may be hampered due to abundant growth of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae during enrichment, resulting in false-negative samples. Therefore, the ISO protocol (ISO-DIS 10272-1; 2015) was revised to include, next to Bolton Broth (BB), Preston Broth (PB) as a prescribed enrichment broth to inhibit competitive flora in samples with suspected high levels of ESBLs. An Inter-Laboratory Study (ILS) was performed to validate this protocol, using four food matrices and chicken caecal material.
Purpose: The ILS validation included one different strain per food matrix; therefore, in the current study, enrichment procedures were carried out with all strains used in the ILS in each food matrix.
Methods: Enrichment procedures according to the ISO protocol were conducted using spinach, minced meat, raw milk, and chicken skin. Each matrix was inoculated with a different strain of Campylobacter jejuni (3 strains) or Campylobacter coli (2 stains).
Results were expressed as LOD50 (Level of Detection), which is the concentration at which the probability of detection is 50%.
Results: The LOD50 for all strains tested in spinach was approximately 0.7 CFU/sample, which complies with the ILS results. Results for the other food products, however, showed a large variation in the LOD50, with statistically significant differences between food products and between strains in raw milk and minced meat.
Significance: When a laboratory is validating the ISO method, care should be taken to extrapolate the ILS results to other Campylobacter spp. strains. One of the strains used in the ILS (C. jejuni WDCM 00156) is not the best choice to use as the reference strain.
Prediction of cashew nut allergy in sensitized children
Valk, Johanna P.M. van der; Vergouwe, Yvonne ; Wijk, R.G. van; Steyerberg, Ewout W. ; Reitsma, Marit ; Wichers, Harry J. ; Savelkoul, Huub F.J. ; Vlieg-Boerstra, Berber ; Groot, Hans de; Dubois, Anthony E.J. ; Jong, Nicolette W. De - \ 2017
Pediatric Allergy and Immunology 28 (2017)5. - ISSN 0905-6157 - p. 487 - 490.
The cashew allergens : a molecular and serological characterization
Reitsma, Marit - \ 2017
Wageningen University. Promotor(en): H.J. Wichers; H.F.J. Savelkoul, co-promotor(en): N.W. de Jong. - Wageningen : Wageningen University - ISBN 9789463430784 - 186
anacardium occidentale - allergens - serological surveys - protein transport - molecular detection - small intestine - pichia pastoris - in vivo experimentation - sds-page - western blotting - electrophoresis - anacardium occidentale - allergenen - serologische overzichten - eiwittransport - moleculaire detectie - dunne darm - pichia pastoris - in vivo experimenten - sds-page - western blotting - elektroforese

Cashew nut allergy can be a severe food allergy of which the prevalence appears to be increasing. The aim of this thesis was a comprehensive molecular and serological characterisation of the cashew nut allergens Ana o 1, 2 and 3 for improved diagnosis and characterisation of patient populations.

Chapter 1 in this thesis provides background information on cashew nuts, allergy, the allergens Ana o 1, 2 and 3, the effect of heat treatments on cashew nut proteins, the digestibility of cashew nut proteins, cross-reactivity between cashew nut proteins and other tree nuts, and the detection of cashew nut in food products. Subsequently, in Chapter 2, a review is presented on the topic of epithelial protein and allergen transport. This review describes multiple pathways of intestinal protein transport, sums up existing experimental data concerning protein and peptide transport, and presents different methods to study this. Interestingly, the pathway of (allergenic) protein transport can differ between sensitized and non-sensitized persons. In sensitized persons, protein transport occurs transcellularly via enterocytes, and paracellularly with the involvement of mast cells, while in non-sensitized persons microfold cells and enterocytes are considered most important.

In the next three chapters, cashew nut allergens were studied. Cashew nut allergy and cashew nut allergens were chosen because of a high number of undiagnosed cashew nut allergic children reported at the children’s hospital “Kinderhaven”, in Rotterdam, an outpatient clinic that is involved in this study. Chapter 3 describes a protocol for the purification of Ana o 1, 2 and 3 from cashew nuts. Ana o 1 and 3 were purified by protein extraction, salt precipitation and filtering over a 30kDa molecular weight membrane. Ana o 2 was purified by protein extraction followed by gel filtration chromatography. These purified proteins were characterised by SDS-PAGE, western blot, glycoprotein stain, and protein identification. In this chapter also more in-depth analysis was performed on the N- and C-termini of the large and small subunits of Ana o 3. These N- and C-termini of Ana o 3, as well as the SDS-PAGE protein profiles were compared between cashew nuts of different origins in Chapter 4. In this chapter also the effects of different heat treatments on the electrophoretic behaviour of cashew nut allergens from various origins were studied, using both 1D and 2D electrophoresis. In these data no significant differences were detected between the electrophoresis patterns of Ana o 1, 2 or 3 in the various origins of cashew nuts. Some small but significant differences in Ana o 1, 2 and 3 content, however, were detected between the differently heated cashew nuts. No major differences in N- and C-terminal micro-heterogeneity were detected between cashew nuts of different origins.

Next, in Chapter 5, the cashew nut allergens Ana o 1, 2 and 3 were produced as recombinant proteins using a yeast (P. pastoris) production system. This procedure was used as recombinant allergens often produce higher yields of higher purity compared to native purified allergens. The recombinant proteins were compared to the native cashew nut proteins for their glycosylation pattern, IgE binding capacity, and 2D electrophoresis profile. In Chapter 6, the major findings of this thesis are discussed. An overview of the protein characteristics (e.g. 1D and 2D electrophoresis profile, glycosylation, IgE binding, pepsin-digestibility) was provided, as well as a discussion on the clinical benefits that can be derived from the results obtained in this thesis. Also some additional results are presented, studying the serologic cross-reactivity between cashew nuts and other tree nuts and Anacardiaceae nuts and fruits.

This thesis provides an in-depth study regarding the protein characteristics of the cashew nut allergens Ana o 1, 2 and 3. Using the allergens that were purified in this thesis project, the serum IgE levels of Ana o 1, 2 and 3 could be measured in cashew nut-allergic children. The allergens were also recombinantly produced to obtain higher quantity of allergens for regular use in diagnostics of cashew nut allergy. The results from this thesis can potentially expand clinical patient characterisation with measurements of IgE levels to purified and recombinantly produced major cashew nut allergens. These results might have applications for other food allergens or patient populations.

sIgE Ana o 1, 2 and 3 accurately distinguish tolerant from allergic children sensitized to cashew nuts
Valk, J.P.M. van der; Gerth van Wijk, R. ; Vergouwe, Y. ; Steyerberg, E.W. ; Reitsma, M. ; Wichers, H.J. ; Savelkoul, H.F.J. ; Vlieg-Boerstra, B. ; Groot, H. de; Dubois, A.E.J. ; Jong, N.W. de - \ 2017
Clinical and Experimental Allergy 47 (2017)1. - ISSN 0954-7894 - p. 113 - 120.
Ana o 2 and Ana o 3 - Cashew nut allergy - Children - Component-resolved diagnosis - Components Ana o 1 - Food challenge test

Background: The double-blind, placebo-controlled food challenge test (DBPCFC) is the gold standard in cashew nut allergy. This test is costly, time consuming and not without side effects. Analysis of IgE reactivity to cashew nut components may reduce the need for food challenge tests. Methods: In a prospective and multicentre study, children with suspected cashew nut allergy underwent a DBPCFC with cashew nut. Specific IgE to cashew nut and to the components Ana o 1, 2 and 3 were determined. A skin prick test (SPT) with cashew nut extract was performed. The association between the outcome of the food challenge test and specific IgE to Ana o 1, 2 and 3 was assessed with logistic regression analyses, unadjusted and adjusted for other diagnostic variables. Discriminative ability was quantified with a concordance index (c). Results: A total of 173 children (103 boys, 60%) with a median age of 9 years were included. About 79% had a positive challenge test outcome. A steep rise in the risk of a positive challenge was observed for specific IgE to each individual component Ana o 1, 2 and 3 with estimated risks up to approximately 100%. Median values of Ana o 1, 2, 3 were 1.29 kU/l (range 0-100 kU/l), 4.77 kU/l (range 0-100 kU/l) and 8.33 kU/l (range 0-100 kU/l) respectively and varied significantly (p <0.001). Specific IgE to Ana o 1, 2 and 3 was better distinguished between cashew-allergic and tolerant children (c = 0.87, 0.85 and 0.89, respectively) than specific IgE to cashew nut or SPT (c = 0.76 and 0.83, respectively). Conclusion: The major cashew nut allergens Ana o 1, 2 and 3 are each individually predictive for the outcome of food challenge tests in cashew-allergic children.

Growth kinetics of Campylobacter jejuni and ESBLs in enrichment procedures
Hazeleger, W.C. ; Lanzl, M.I. ; Jacobs-Reitsma, W.F. ; Besten, H.M.W. den - \ 2016
Large impact of Campylobacter strain and food matrix on LOD50 result
Hazeleger, W.C. ; Jacobs-Reitsma, W.F. ; Jongenburger, I. ; Besten, H.M.W. den - \ 2016
Quantification of Growth of Campylobacter and Extended Spectrum β-Lactamase Producing Bacteria Sheds Light on Black Box of Enrichment Procedures
Hazeleger, Wilma C. ; Jacobs-reitsma, Wilma F. ; Besten, Heidy M.W. den - \ 2016
Frontiers in Microbiology 7 (2016). - ISSN 1664-302X - 9 p.
Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide, and is routinely found in meat originating from poultry, sheep, pigs, and cattle. Effective monitoring of Campylobacter contamination is dependent on the availability of reliable detection methods. The method of the International Organization for Standardization for the detection of Campylobacter spp. in food (ISO 10272-1:2006) recommends the use of Bolton broth (BB) as selective enrichment medium, including a pre-enrichment step of 4–6 h at 37°C to revive sublethally damaged cells prior to incubation for 2 days at 41.5°C. Recently the presence of abundantly growing extended spectrum β-lactamase producing Enterobacteriaceae (ESBL bacteria) has become one of the most important factors that interfere with the isolation of Campylobacter, resulting in false-negative detection. However, detailed growth dynamics of Campylobacter and its competitors remain unclear, where these would provide a solid base for further improvement of the enrichment procedure for Campylobacter. Other enrichment broths, such as Preston broth (PB) and BB plus clavulanic acid (BBc) have been suggested to inhibit competitive flora. Therefore, these different broths were used as enrichments to measure the growth kinetics of several strains of Campylobacter jejuni and ESBL bacteria separately, in co-culture and of strains in chicken samples. The maximum cell numbers and often the growth rates of Campylobacter in mixed culture with ESBL bacteria were significantly lower than in single cultures, indicating severe suppression of Campylobacter by ESBL bacteria, also in naturally contaminated samples. PB and BBc successfully diminished ESBL bacteria and might therefore be a better choice as enrichment medium in possibly ESBL-bacteria contaminated samples. The efficacy of a pre-enrichment step in the BB ISO-procedure was not supported for cold-stressed and non-stressed cells. Therefore, omission of this step (4–6 h at 37°C) might be advised to obtain a less troublesome protocol.
Multicentre double-blind placebo-controlled food challenge study in children sensitised to cashew nut
Valk, J.P.M. van der; Gerth van Wijk, R. ; Dubois, A.E.J. ; Groot, H. de; Reitsma, M. ; Vlieg-Boerstra, B.J. ; Savelkoul, H.F.J. ; Wichers, H.J. ; Jong, N.W. de - \ 2016
PLoS ONE 11 (2016)3. - ISSN 1932-6203 - 12 p.
Background
Few studies with a limited number of patients have provided indications that cashew-allergic patients may experience severe allergic reactions to minimal amounts of cashew nut. The objectives of this multicentre study were to assess the clinical relevance of cashew nut sensitisation, to study the clinical reaction patterns in double-blind placebo-controlled food challenge tests and to establish the amount of cashew nuts that can elicit an allergic reaction.

Methods and Findings
A total of 179 children were included (median age 9.0 years; range 2–17 years) with cashew nut sensitisation and a clinical history of reactions to cashew nuts or unknown exposure. Sensitised children who could tolerate cashew nuts were excluded. The study included three clinical visits and a telephone consultation. During the first visit, the medical history was evaluated, physical examinations were conducted, blood samples were drawn and skin prick tests were performed. The children underwent a double-blind placebo-controlled food challenge test with cashew nut during the second and third visits. The study showed that 137 (76.5%) of the sensitised children suspected of allergy to cashew nut had a positive double-blind placebo-controlled food challenge test, with 46% (63) manifesting subjective symptoms to the lowest dose of 1 mg cashew nut protein and 11% (15) developing objective symptoms to the lowest dose. Children most frequently had gastro-intestinal symptoms, followed by oral allergy and skin symptoms. A total of 36% (49/137) of the children experienced an anaphylactic reaction and 6% (8/137) of the children were treated with epinephrine.

Conclusion
This prospective study demonstrated a strikingly high percentage of clinical reactions to cashew nut in this third line population. Severe allergic reactions, including anaphylaxis requiring epinephrine, were observed. These reactions were to minimal amounts of cashew nut, demonstrated the high potency of this allergens.
Purification and Characterization of Anacardium occidentale (Cashew) Allergens Ana o 1, Ana o 2, and Ana o 3
Reitsma, Marit ; Bastiaan-Net, Shanna ; Sforza, Stefano ; Valk, J.P.M. Van Der; Gerth Van Wijk, Roy Van; Savelkoul, H.F.J. ; Jong, N.W. De; Wichers, H.J. - \ 2016
Journal of Agricultural and Food Chemistry 64 (2016)5. - ISSN 0021-8561 - p. 1191 - 1201.
Ana o 1 - Ana o 2 - Ana o 3 - cashew - tree nut allergy

In this study a fast and simple purification procedure for the three known allergens from cashew (7S globulin Ana o 1, 11S globulin Ana o 2, and 2S albumin Ana o 3) is described. The purified allergens are characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, glycoprotein stain, and protein identification. The purified proteins still bind IgE, and this IgE binding varied between different pools of patient serum. Ana o 1 was found to be a glycoprotein. Ana o 3 has been studied more in detail to identify both the small and large subunits, both displaying microheterogeneity, and epitope mapping of Ana o 3 has been performed.

LOD50 is dependent on choice of Campylobacter strain and food matrix
Hazeleger, W.C. ; Veljkovic Cvoric, L. ; Jacobs-Reitsma, W.F. ; Besten, H.M.W. den - \ 2015
- 1 p.
Due to abundant growth of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae during enrichment it is hard to isolate and recognize Campylobacter colonies on mCCDA. Therefore, in the current revision of the ISO protocol (ISO 10272-1), next to Bolton Broth (BB), Preston broth (PB) is suggested as enrichment broth to inhibit competitive fl ora in samples where high levels of background fl ora such as ESBLs are suspected.
To validate this revised ISO 10272-1, an Inter Laboratory Study (ILS) was performed where diff erent matrices were used in the enrichment procedures: frozen spinach, minced meat, raw milk and chicken skin. Each matrix was
inoculated with a diff erent strain of C. jejuni or C. coli and the results were expressed as LOD50 (Level of Detection) which is the lowest contamination level that can be detected with a probability of 50%. Since diff erent strains
were used for each matrix, results of the ILS are possibly infl uenced by the strains’ characteristics. Therefore, in this study we tested the enrichment procedures for spinach, minced meat, milk and chicken skin with each of
the strains used in the ILS. The LOD50 of all strains tested in spinach was in the range of 0.7 cfu/sample which complies with the ILS-results and which is also the theoretical value. Preliminary results for the other product types, however, show a large variation of LOD50 between strains which indicates that the choice of strain will infl uence the LOD50. In conclusion care should be taken to extrapolate the ILS results to other strains.
Preston Broth and Bolton Broth plus clavulanic acid suppress ESBLs sufficiently in Campylobacter enrichment procedures
Hazeleger, W.C. ; Zhang, J. ; Jacobs-Reitsma, W.F. ; Besten, H.M.W. den - \ 2015
- 1 p.
The presence and increase of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in food have become important factors that interfere with the isolation of Campylobacter, resulting in false-negative detection results. The ISO-protocol for detection of thermotolerant Campylobacter spp. in food and animal
feeding stuff s (ISO 10272-1, 2006) describes the use of Bolton broth (BB) which is mixed 10:1 with the food sample including a pre-enrichment step at 37°C to resuscitate sublethally damaged cells. Currently, the ISOprotocol is revised and a distinction is made between diff erent food samples, where the more selective Preston Broth (PB) is advised for samples in which high background fl ora such as ESBLs is suspected. However, detailed growth dynamics of Campylobacter and its competitors during enrichment remain unclear, while these would provide a solid base for further improvement of the enrichment procedure of ampylobacter. Therefore, growth kinetics were studied in detail using several strains of C. jejuni and ESBLs combined and separately in BB, PB and BB supplemented with clavulanic acid (BBc). Also, growth dynamics of ampylobacter and ESBLs in naturally contaminated chicken samples were evaluated. No signifi cant diff erences in growth kinetics were found using a pre-enrichment step of 4 h at 37°C compared to immediate enrichment at 41.5°C. Furthermore, the yields and often the growth rates of Campylobacter in co-culture with ESBLs were lower than in pure cultures, indicating severe suppression of Campylobacter by ESBLs. PB and BBc, however, successfully inhibited growth of ESBLs and are therefore a better choice as enrichment media for potentially ESBL-contaminated samples.
Everything you Always wanted to know about Campylobacter
Jacobs-Reitsma, W.F. ; Hazeleger, W.C. - \ 2015
- 1 p.
Did you know that...
... growth of campylobacters in liquid medium like Heart Infusion Broth is hardly visible, and if nice and thick growth does show this most likely means a contamination in your broth. ... vented Petri-dishes should be used to facilitate the growth in micro-aerobic atmosphere, but also help to be able to re-open the dishes after incubation. ... a Campylobacter-selective agar plate like CCDA may look like showing no growth, but in practice may contain a thin layer of growth all over the plate and only just giving the impression to be negative for growth. Check with loop on presence of colony mass! We would like to share our over 25 years of working-with-Campylobacter-experience with the audience. Preferably in an interactive way by asking the audience for their own experience and starting-up questions, but at least by presenting a practical “picture” of this ever surprising micro-organism.
Impact of sample size on the Limit of Detection LOD50 to detect Campylobacter in foods
Jacobs-Reitsma, W.F. ; W.M., Van Overbeek ; Hazeleger, W.C. ; Jongenburger, I. - \ 2015
The European Commission Mandate M/381 asked the European Committee for Standardization (CEN) to provide full validation of the revised versions of ISO 10272-1/-2 by inter-laboratory studies and to establish the performance characteristics of these ISO methods for detection and enumeration of Campylobacter in foods. After fi nalising the study on Campylobacter detection, the elaborated data were inserted in ISO 10272- 1. Results are expressed as the limit of detection at 50% (LOD50): the concentration in CFU/sample for which the probability of detection is 50%. No legislative requirements within the EU exist for testing on presence of
Campylobacter in a specifi c portion size, in contrast to e.g. the requirement for absence of Salmonella in 25 gram (EC 2073/2005). Therefore, for practical and economic reasons, the size of the test portions in the validation study on detection of Campylobacter was decided to be 10 gram. As test portions of 25 gram are also commonly used in detection methods, our laboratory compared the LOD50 for Campylobacter detection in 10 gram and 25 gram
test portions of foods. Matrices as used in the inter-laboratory study were tested, using both samples sizes with identical inoculum at 2 diff erent levels (and a blank as control) and the LOD50 was calculated for each sample size. Preliminary results indicate better Campylobacter detection in 10 gram portions of minced meat and frozen spinach, in contrast to better detection in 25 gram portions of raw milk. Experiments are ongoing to elucidate
the possible eff ect of sample size on the LOD50.
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