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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Erwinia pyrifoliae as a new pathogen on strawberry in the Netherlands
Wenneker, M. ; Bergsma-Vlami, M.M. - \ 2014
In: Book of abstracts VIII Workshop on Integrated Soft Fruit Production. - Vigalzano di Pergine Valsugana (TN) : Fondazione Edmund Mach - p. 3 - 4.
During the late spring in 2013 strawberry plants (Fragaria x ananassa cv. Elsanta) were found at several locations in the Netherlands showing an intense blackening of their immature fruits, their fruit calyx and the attached stems. There were no symptoms observed on the leaves. The discoloration was also observed inside the young fruits, which presented an intense darkening or blackening of the fruit tissue at the edges and an intense shining of the fruit tissue in the middle. Fruits did not develop or were in many cases heavily malformed. In certain cases 40% of the crop was lost. The release of bacterial slime was additionally observed on the surface of the young fruits and their stems. Isolations from these symptomatic immature strawberry fruits yielded Erwinia-like colonies on YPG (Yeast Peptone Glucose) agar. Characterization of the isolates revealed Gram negative bacterial cells, giving a negative reaction on Levan, and on media containing pectin. Bacteria have the following biochemical features: positive for sorbitol, but negative for gelatine, esculin and D-raffinose. The isolates differed biochemically from E. amylovora and they were closely related to biochemical profiles of the Erwinia pyrifoliae reference strain LMG 25888. The isolates were further identified as E. pyrifoliae based on the real time PCR assay (Wensing et al., 2012). Pathogenicity of several isolates was tested and confirmed on potted strawberry plants (cv. Elsanta). Inoculation by injecting a thick bacterial suspension (108 cfu/ml) in the epicalyx of three immature strawberry fruits per plant quickly resulted in oily necrosis with abundant formation of exudate on the epicalyx and on the sepals. A few inoculated fruitlets with the isolates and E. pyrifoliae reference strain LMG 25888 developed similar symptoms to the ones observed in the original samples in three to four weeks. The bacterium was re-isolated from the affected symptomatic fruitlets and identity of the re-isolates was confirmed by PCR, indicating that E. pyrifoliae had caused the disease. Spray inoculation of strawberry flowers resulted in necrosis without ooze formation. Erwinia pyrifoliae is closely related to the main fire blight pathogen E. amylovora. The pathogen E. pyrifoliae was described for the first time in 1999 in Korea (Kim et al., 1999; 2001). E. pyrifoliae is primarily a pathogen of Asian or Nashi pear (Pyrus pyrifolia) causing fire blight on Nashi pear and is considered to have a restricted geographic distribution in East Asia (Korea and Japan). Thus far occurrence of this pathogen on strawberry has not been reported nor its presence outside Asia.
Multiplex Diagnostics
Wal, Fimme Jan van der - \ 2012
One plasmid system for the production of non-spreading Rift Valley Fever Virus
Kortekaas, Jeroen - \ 2011
Rift Valley Fever Vaccine development at CVI
Moormann, Rob - \ 2011
Dutch organizations involved in the financing of forests and nature in tropical countries : a directory
Bade, T. ; Wensing, D. ; Enzerink, R. ; Wageningen International, - \ 2009
[Wageningen] : Wageningen University and Research Centre - 121
bossen - bosbouw - natuurbescherming - nederland - adresboeken - tropen - financieren - forests - forestry - nature conservation - netherlands - directories - tropics - financing
Associations between Energy Metabolism, LH Pulsatility and First Ovulation in early Lactating Cows
Jorritsma, R. ; Langendijk, P. ; Kruip, T.A.M. ; Wensing, T.H. ; Noordhuizen, J.P.T.M. - \ 2005
Reproduction in Domestic Animals 40 (2005)1. - ISSN 0936-6768 - p. 68 - 72.
dairy-cows - ovarian activity - dry period - postpartum - cattle - balance - secretion - hormone - leptin - number
This study was designed to elucidate associations between energy metabolism and LH pulsatility characteristics in early lactation, and days to first ovulation, in order to explain the relationship between energy balance and fertility observed in epidemiological studies. To this end, 10 multiparous HF cows were monitored during lactation, after the application of two different feeding strategies during the dry period. Days to first ovulation was assessed using blood progesterone measurements and LH pulsatility was measured in 8-h windows in the third week postpartum. The association between depth of negative energy balance and days to ovulation was confirmed. However, this study does not support the idea that LH pulsatility characteristics in early lactation are predictive for the interval between parturition and first ovulation
Metabolic homeostasis in postpartum dairy cows hampered by fatty livers
Jorritsma, R. ; Murondoti, A. ; Vos, P. ; Noordhuizen, J.P.T.M. ; Kruip, T.A.M. ; Wensing, T. - \ 2004
Veterinary Record 155 (2004)5. - ISSN 0042-4900 - p. 151 - 152.
hepatic triacylglycerol - dry period - lipidosis - herds
Sensory testing of recipes masking peanut or hazelnut for double-blind placebo-controlled food challenges
Ronteltap, A. ; Schaik, J. van; Wensing, M. ; Rynja, F.J. ; Knulst, A.C. ; Vries, J.H.M. de - \ 2004
Allergy 59 (2004)4. - ISSN 0105-4538 - p. 457 - 460.
allergy - diagnosis
Background: In a double-blind placebo-controlled food challenge (DBPCFC), it is necessary that recipes comprising the allergen cannot be distinguished from placebo. Aims of the study: We investigated whether the method of paired comparisons, a sensory difference test, could be used to test the suitability of recipes for a DBPCFC. Methods: We used two recipes, each with three concentrations of peanut or hazelnut flour. The recipe for peanut consisted of mashed potatoes with 2.7, 8.9, or 26.8 mg of peanut flour, and the recipe for hazelnut of oatmeal porridge with 74, 247, or 742 mg of hazelnut flour. Corresponding amounts of protein in the provided 15 g portions of each recipe were 0.7, 2.3, and 6.8 mg for peanut, and 11.6, 39, and 117 mg for hazelnut, respectively. Recipes were offered together with a placebo, and evaluated on sensory features by 81 healthy volunteers. Results: The sensory test was easy to perform. Volunteers were not able to detect peanut flour in mashed potatoes, but they recognized hazelnut flour in oatmeal porridge on visual features. Conclusions: Sensory testing by means of the method of paired comparisons is a useful method to evaluate masking of foods for DBPCFC.
Patients with anaphylaxis to pea can have peanut allergy caused by cross-reactive IgE to vicilin (Ara h 1)
Wensing, M. ; Knulst, A.C. ; Piersma, S.R. ; O'Kane, F.E. ; Knol, E.F. ; Koppelman, S.J. - \ 2003
Journal of Allergy and Clinical Immunology 111 (2003)2. - ISSN 0091-6749 - p. 420 - 424.
legume botanical family - pisum-sativum-l - food hypersensitivity - atopic-dermatitis - allergenicity - children - identification - proteins - challenges - binding
Background: Serologic cross-reactivity among legumes has been described; however, it is rarely clinically significant. In this study 3 patients with a history of anaphylaxis to pea are described who subsequently had symptoms after ingestion of peanut. Objective: We investigated whether the peanut-related symptoms were due to cross-reactivity between pea and peanut proteins. Methods: Peanut-related symptoms were documented according to case history or double-blind, placebo-controlled food challenge results. Skin prick tests were performed, and specific IgE levels were determined for pea and peanut with the CAP system FEIA. IgE-binding proteins in pea and peanut were identified by using immunoblot analysis. Cross-reactivity was studied by means of immunoblot and ELISA inhibition studies with whole extracts and purified allergens. Results: Peanut-related symptoms consisted of oral symptoms in all patients, with additional urticaria and dyspnea or angioedema in 2 patients. All patients had a positive skin prick test response and an increased IgE level to pea and peanut. Immunoblotting revealed strong IgE binding to mainly vicilin in pea extract and exclusively to Ara h 1 in crude peanut extract. Immunoblot and ELISA inhibition studies with crude extracts, as well as purified proteins, showed that IgE binding to peanut could be inhibited by pea but not or only partially the other way around. Conclusion: Clinically relevant cross-reactivity between pea and peanut does occur. Vicilin homologues in pea and peanut (Ara h 1) are the molecular basis for this cross-reactivity
Peanut allergen Ara h 3: Isolation from peanuts and biochemical characterization.
Koppelman, S.J. ; Knol, E.F. ; Vlooswijk, R.A.A. ; Wensing, M. ; Knulst, A.C. ; Hefle, S.L. ; Gruppen, H. ; Piersma, S.R. - \ 2003
Allergy 58 (2003)11. - ISSN 0105-4538 - p. 1144 - 1151.
ara-h-i - atopic-dermatitis - ige binding - identification - glycinin - proteins - sera - hypersensitivity - epitopes - cloning
Background: Peanut allergen Ara h 3 has been the subject of investigation for the last few years. The reported data strongly depend on recombinant Ara h 3, since a purification protocol for Ara h 3 from peanuts was not available. Methods: Peanut allergen Ara h 3 (glycinin), was purified and its posttranslational processing was investigated. Its allergenic properties were determined by studying IgE binding characteristics of the purified protein. Results: Ara h 3 consists of a series of polypeptides ranging from approximately 14 to 45 kDa that can be classified as acidic and basic subunits, similar to the subunit organization of soy glycinin. N-terminal sequences of the individual polypeptides were determined, and using the cDNA deduced amino-acid sequence, the organization into subunits was explained by revealing posttranslational processing of the different polypeptides. IgE-binding properties of Ara h 3 were investigated using direct elisa and Western blotting with sera from peanut-allergic individuals. The basic subunits, and to a lesser extent the acidic subunits, bind IgE and may act as allergenic peptides. Conclusions: We conclude that peanut-derived Ara h 3, in contrast to earlier reported recombinant Ara h 3, resembles, to a large extent, the molecular organization typical for proteins from the glycinin family. Furthermore, posttranslational processing of Ara h 3 affects the IgE-binding properties and is therefore an essential subject of study for research on the allergenicity of Ara h 3.
How accurate and safe is diagnosis of hazelnut allergy by means of commercial skin prick test reagents?
Akkerdaas, J.H. ; Wensing, M. ; Knulst, A.C. ; Krebitz, M. ; Breiteneder, H. ; Vries, S.C. de; Penninks, A.H. ; Aalberse, R.C. ; Hefle, S.L. ; Ree, R. van - \ 2003
International Archives of Allergy and Immunology 132 (2003). - ISSN 1018-2438 - p. 132 - 140.
lipid transfer protein - major allergen - double-blind - cross-reactivity - vegetable foods - brazil-nut - identification - pollen - ige - peanut
Background: Allergy to tree nuts, like hazelnuts, ranks among the most frequently observed food allergies. These allergies can start at early childhood and are, in contrast to other food allergies, not always outgrown by the patient. Tree nut allergy is frequently associated with severe reactions. Diagnosis partially relies on in vivo testing by means of a skin prick test (SPT) using commercially available SPT reagents. Methods: Protein and allergen composition of nine commercial SPT solutions was evaluated using standard protein detection methods and specific immunoassays for measurement of five individual allergens. Diagnostic performance was assessed by SPT in 30 hazelnut-allergic subjects, of which 15 were provocation proven. Results: Protein concentrations ranged from 0.2-14 mg/ml. SDS-PAGE/silver staining revealed clear differences in protein composition. The major allergen Cor a 1 was present in all extracts but concentrations differed up to a factor 50. An allergen associated with severe symptoms, Cor a 8 (lipid transfer protein), was not detected on immunoblot in three products, and concentrations varied by more than a factor 100 as was shown by RAST inhibition. Similar observations were made for profilin, thaumatin-like protein and a not fully characterized 38-kD allergen. Ratios of individual allergens were variable among the nine extracts. SPT showed significant difference, and 6/30 patients displayed false-negative results using 3/9 products. Conclusion: Variability in the composition of products for the diagnosis of hazelnut allergy is extreme. Sometimes, allergens implicated in severe anaphylaxis are not detected by immunoblotting. These shortcomings in standardisation and quality control can potentially cause a false-negative diagnosis in subjects at risk of severe reactions to hazelnuts. Copyright (C) 2003 S. Karger AG, Basel.
Acute fasting in heifers as a model for assessing the relationship between plasma and follicular fluid NEFA concentrations.
Jorritsma, R. ; Groot, M.W. de; Vos, P.L.A.M. ; Kruip, T.A.M. ; Wensing, T. ; Noordhuizen, J.P.T.M. - \ 2003
Theriogenology 60 (2003)1. - ISSN 0093-691X - p. 151 - 161.
growth-factor-i - preovulatory lh surge - energy-balance - dairy-cows - beef heifers - ovarian follicle - bovine follicles - milk-production - body condition - holstein cows
It is known from epidemiological studies that negative energy balance in early lactating dairy cows is related to a depression in reproductive performance. Elevated plasma concentrations of non-esterified fatty acids (NEFA) are a typical metabolic characteristic of these animals and are proposed as the possible link. The suggestion is that NEFA might have a direct effect on the ovary, by affecting development of the oocyte or the granulosa cells. However, no data is available concerning the relationship between the concentration of NEFA in follicular fluid and plasma. Therefore, a cross-over study with 10 heifers around 15 months of age was conducted to analyze this relationship and examine the suggested effects of the negative energy balance on follicular growth. Investigation of these effects was performed on fasted heifers. The experimental treatment consisted of feeding hay with a subsequent period of fasting, to induce elevated plasma NEFA concentrations. Sampling of follicular fluid was performed using transvaginal aspiration of follicles, which were standardized using a synchronization protocol. In addition, concentrations of glucose, insulin, NEFA, and estradiol were measured in plasma. Follicular estradiol and progesterone concentrations were also measured to assess the quality of the dominant follicle. Fasting resulted in significantly lower plasma glucose (P=0.0006) and plasma insulin (P
Metabolic changes in early lactation and impaired reproductive performance in dairy cows.
Jorritsma, R. ; Wensing, T. ; Kruip, T.A.M. ; Vos, P.L.A.M. ; Noordhuizen, J.P.T.M. - \ 2003
Veterinary Research 34 (2003)1. - ISSN 0928-4249 - p. 11 - 26.
growth-factor-i - early postpartum period - energy-balance - first ovulation - holstein cows - luteinizing-hormone - milk-production - body condition - fatty liver - food-intake
This review addresses the suggestion that the decline in dairy reproductive performance, as increasingly observed these days, may be due to a hampered process of metabolic adaptation in early lactating cows. In our opinion, adaptation to the negative energy balance is a gradual process. Because almost all cows do adapt in the long run, it is not possible to classify animals as adapted or non-adapted. The use of risk factors is more appropriate in this case and is discussed in this review. Among them are the body condition score and its derivatives, feed intake, the calculated negative energy balance, and metabolic parameters like the plasma concentration of insulin or the triacylglycerol content in the liver. Moreover, factors that play a role in the link between declined reproductive performance and the metabolic situation of the cow during the early lactating period are discussed. Among these are insulin, insulin-like growth factors, leptin, neuropeptide Y, non-esterified fatty acids, thyroid hormones, urea, and ammonia.
Post-partum supplementation with rumen undegradable protein not reduce fatty acid liver development in dairy cows as induced by overfeeding during the dry period
Murandot, A. ; Rukkwamsuk, T. ; Kruip, T.A.M. ; Wensing, T. ; Meijer, G.A.L. ; Beynen, A.C. - \ 2002
Journal of Animal Physiology and Animal Nutrition (2002). - ISSN 0931-2439
Characteristics of abnormal puerperium in dairy cattle and the retionale for common treatments
Kruip, T.A.M. ; Wensing, T. ; Vos, P.L.A.M. - \ 2001
Occasional publication of the British society of animal science 26 (2001). - p. 63 - 79.
An investigation into the mechanism by which the negative energy balance affects the fertility and reproductive performance of the high yielding dairy cow post partum
Kruip, Th.A.M. ; Meijer, G.A.L. ; Rukkwamsuk, T. ; Wensing, T. - \ 1999
In: Proceedings 10th ICPD / Edites by Th. Wensing. - 1999. - 183-190
Relationships between overfeeding and overconditioning in the dry period and the problems of high producing dairy cows during the postparturient period
Rukkwamsuk, T. ; Kruip, T.A.M. ; Wensing, T. - \ 1999
Veterinary Quarterly 21 (1999). - ISSN 0165-2176 - p. 71 - 77.
Relationship between triacylglycerol concentration in the liver and first ovulation in postpartum dairy cows
Rukkwamsuk, T. ; Wensing, T. ; Kruip, T.A.M. - \ 1999
Theriogenology 51 (1999). - ISSN 0093-691X - p. 1133 - 1142.
Hepatic Fatty Acid Composition in Periparturient Dairy Cows with Fatty Liver Induced by Intake of a High Energy Diet in the Dry Period
Rukkwamsuk, T. ; Kruip, T.A.M. ; Meijer, G.A.L. ; Wensing, T. - \ 1999
Journal of Dairy Science 82 (1999)2. - ISSN 0022-0302 - p. 280 - 287.
The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacylglycerol concentration and to a shift in hepatic fatty acid composition.
Influence of dry cow management on oestrus expression in dairy cows
Eerdenburg, F.J.C.M. van; Landman, B. ; Wensing, T. ; Kruip, Th.A.M. - \ 1999
In: Proceedings 10th ICPD abstract - p. 195 - 195.
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