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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    First international descriptive and interventional survey for cholesterol and non-cholesterol sterol determination by gas- and liquid-chromatography–Urgent need for harmonisation of analytical methods
    Lütjohann, Dieter ; Björkhem, Ingemar ; Friedrichs, Silvia ; Kerksiek, Anja ; Lövgren-Sandblom, Anita ; Geilenkeuser, Wolf Jochen ; Ahrends, Robert ; Andrade, Isabel ; Ansorena, Diana ; Astiasarán, Iciar ; Baila-Rueda, Lucía ; Barriuso, Bianca ; Becker, Susen ; Bretillon, Lionel ; Browne, Richard W. ; Caccia, Claudio ; Ceglarek, Uta ; Cenarro, Ana ; Crick, Peter J. ; Fauler, Günter ; Garcia-Llatas, Guadalupe ; Gray, Robert ; Griffiths, William J. ; Gylling, Helena ; Harding, Scott ; Helmschrodt, Christin ; Iuliano, Luigi ; Janssen, Hans Gerd ; Jones, Peter ; Kaipiainen, Leena ; Kannenberg, Frank ; Lagarda, María Jesús ; Leoni, Valerio ; Lottenberg, Ana Maria ; MacKay, Dylan S. ; Matysik, Silke ; McDonald, Jeff ; Menendez-Carreño, Maria ; Myrie, Semone B. ; Sutti Nunes, Valéria ; Ostlund, Richard E. ; Polisecki, Eliana ; Ramos, Fernando ; Rideout, Todd C. ; Schaefer, Ernst J. ; Schmitz, Gerd ; Wang, Yuqin ; Zerbinati, Chiara ; Diczfalusy, Ulf ; Schött, Hans Frieder - \ 2019
    Journal of Steroid Biochemistry and Molecular Biology 190 (2019). - ISSN 0960-0760 - p. 115 - 125.
    Atherosclerosis - Cholesterol absorption - Cholesterol balance - Cholesterol synthesis - Phytosterols - Surrogate marker

    Serum concentrations of lathosterol, the plant sterols campesterol and sitosterol and the cholesterol metabolite 5α-cholestanol are widely used as surrogate markers of cholesterol synthesis and absorption, respectively. Increasing numbers of laboratories utilize a broad spectrum of well-established and recently developed methods for the determination of cholesterol and non-cholesterol sterols (NCS). In order to evaluate the quality of these measurements and to identify possible sources of analytical errors our group initiated the first international survey for cholesterol and NCS. The cholesterol and NCS survey was structured as a two-part survey which took place in the years 2013 and 2014. The first survey part was designed as descriptive, providing information about the variation of reported results from different laboratories. A set of two lyophilized pooled sera (A and B) was sent to twenty laboratories specialized in chromatographic lipid analysis. The different sterols were quantified either by gas chromatography-flame ionization detection, gas chromatography- or liquid chromatography-mass selective detection. The participants were requested to determine cholesterol and NCS concentrations in the provided samples as part of their normal laboratory routine. The second part was designed as interventional survey. Twenty-two laboratories agreed to participate and received again two different lyophilized pooled sera (C and D). In contrast to the first international survey, each participant received standard stock solutions with defined concentrations of cholesterol and NCS. The participants were requested to use diluted calibration solutions from the provided standard stock solutions for quantification of cholesterol and NCS. In both surveys, each laboratory used its own internal standard (5α-cholestane, epicoprostanol or deuterium labelled sterols). Main outcome of the survey was, that unacceptably high interlaboratory variations for cholesterol and NCS concentrations are reported, even when the individual laboratories used the same calibration material. We discuss different sources of errors and recommend all laboratories analysing cholesterol and NCS to participate in regular quality control programs.

    New records and updated checklist of mosquitoes (Diptera: Culicidae) from Lao People's Democratic Republic, with special emphasis on adult and larval surveillance in Khammuane Province
    Motoki, Maysa T. ; Vongphayloth, Khamsing ; Rueda, Leopoldo M. ; Miot, Elliott F. ; Hiscox, Alexandra ; Hertz, Jeffrey C. ; Brey, Paul T. - \ 2019
    Journal of Vector Ecology 44 (2019)1. - ISSN 1081-1710 - p. 76 - 88.
    Culicidae - DNA barcode - Khammuane Province - Lao PDR - mosquito species list - mosquito surveillance

    A list of mosquitoes from the Nakai Nam Theun National Protected Area along the Nam Theun, Nam Mon, Nam Noy, and Nam On rivers, Nakai District, Khammuane Province, Lao People's Democratic Republic (Lao PDR) is presented. Fifty-four mosquito taxa were identified, including 15 new records in the Lao PDR. A fragment of the mtDNA cytochrome c oxidase subunit I (COI) gene, barcode region, was generated for 34 specimens, and together with four specimens already published, it represented 23 species in eight genera. In addition, an updated checklist of 170 mosquito taxa from Lao PDR is provided based on field collections from Khammuane Province, the literature, and specimens deposited in the Smithsonian Institution, National Museum of Natural History (SI-NMNH), Washington, DC, U.S.A. This paper provides additional information about the biodiversity of mosquito fauna in Lao PDR.

    Strategies to Improve Stroke Care Services in Low- and Middle-Income Countries : A Systematic Review
    Pandian, J.D. ; William, Akanksha G. ; Kate, Mahesh P. ; Norrving, Bo ; Mensah, George A. ; Davis, Stephen ; Roth, Gregory A. ; Thrift, Amanda G. ; Kengne, Andre P. ; Kissela, Brett M. ; Yu, Chuanhua ; Kim, Daniel ; Rojas-Rueda, David ; Tirschwell, David L. ; Abd-Allah, Foad ; Gankpé, Fortuné ; Deveber, Gabrielle ; Hankey, Graeme J. ; Jonas, Jost B. ; Sheth, Kevin N. ; Dokova, Klara ; Mehndiratta, Man Mohan ; Geleijnse, Johanna M. ; Giroud, Maurice ; Bejot, Yannick ; Sacco, Ralph ; Sahathevan, Ramesh ; Hamadeh, Randah Ribhi ; Gillum, Richard F. ; Westerman, Ronny ; Akinyemi, Rufus Olusola ; Barker-Collo, Suzanne ; Truelsen, Thomas ; Caso, Valeria ; Rajagopalan, Vasanthan ; Venketasubramanian, Narayanaswamy ; Vlassovi, Vasiliy V. ; Feigin, Valery L. - \ 2017
    Neuroepidemiology 49 (2017)1-2. - ISSN 0251-5350 - p. 45 - 61.

    Background: The burden of stroke in low- and middle-income countries (LMICs) is large and increasing, challenging the already stretched health-care services. Aims and Objectives: To determine the quality of existing stroke-care services in LMICs and to highlight indigenous, inexpensive, evidence-based implementable strategies being used in stroke-care. Methods: A detailed literature search was undertaken using PubMed and Google scholar from January 1966 to October 2015 using a range of search terms. Of 921 publications, 373 papers were shortlisted and 31 articles on existing stroke-services were included. Results: We identified efficient models of ambulance transport and pre-notification. Stroke Units (SU) are available in some countries, but are relatively sparse and mostly provided by the private sector. Very few patients were thrombolysed; this could be increased with telemedicine and governmental subsidies. Adherence to secondary preventive drugs is affected by limited availability and affordability, emphasizing the importance of primary prevention. Training of paramedics, care-givers and nurses in post-stroke care is feasible. Conclusion: In this systematic review, we found several reports on evidence-based implementable stroke services in LMICs. Some strategies are economic, feasible and reproducible but remain untested. Data on their outcomes and sustainability is limited. Further research on implementation of locally and regionally adapted stroke-services and cost-effective secondary prevention programs should be a priority.

    Quantification of transmission of foot-and-mouth disease virus caused by an environment contaminated with secretions and excretions from infected calves
    Bravo De Rueda, C. ; Jong, M. de; Eblé, P.L. ; Dekker, A. - \ 2015
    Veterinary Research 46 (2015). - ISSN 0928-4249
    between-pen transmission - classical swine-fever - vaccinated pigs - actinobacillus-pleuropneumoniae - influenza-viruses - dairy-cows - inactivation - campylobacter - formaldehyde - populations
    Foot-and-mouth disease virus (FMDV) infected animals can contaminate the environment with their secretions and excretions. To quantify the contribution of a contaminated environment to the transmission of FMDV, this study used calves that were not vaccinated and calves that were vaccinated 1 week prior to inoculation with the virus in direct and indirect contact experiments. In direct contact experiments, contact calves were exposed to inoculated calves in the same room. In indirect contact experiments, contact calves were housed in rooms that previously had held inoculated calves for three days (either from 0 to 3 or from 3 to 6 days post inoculation). Secretions and excretions from all calves were tested for the presence of FMDV by virus isolation; the results were used to quantify FMDV transmission. This was done using a generalized linear model based on a 2 route (2R, i.e. direct contact and environment) SIR model that included information on FMDV survival in the environment. The study shows that roughly 44% of transmission occurs via the environment, as indicated by the reproduction ratio ^R0 2R environment that equalled 2.0, whereas the sum of ^R0 2R contact and ^R0 2R environment equalled 4.6. Because vaccination 1 week prior to inoculation of the calves conferred protective immunity against FMDV infection, no transmission rate parameters could be estimated from the experiments with vaccinated calves. We conclude that a contaminated environment contributes considerably to the transmission of FMDV therefore that hygiene measures can play a crucial role in FMD control.
    Foot-and-mouth disease virus : the role of infection routes and species differences in the transmission of FMDV
    Bravo De Rueda Cabrera, C. - \ 2015
    Wageningen University. Promotor(en): Mart de Jong, co-promotor(en): Aldo Dekker; Phaedra Eble. - Wageningen : Wageningen University - ISBN 9789462573284 - 137
    mond- en klauwzeervirus - mond- en klauwzeer - infectieziekten - ziekteoverdracht - ziektebestrijding - infectiebestrijding - soortverschillen - epidemiologie - diergeneeskunde - foot-and-mouth disease virus - foot and mouth disease - infectious diseases - disease transmission - disease control - infection control - species differences - epidemiology - veterinary science

    ÁFoot-and-mouth disease is a contagious viral disease of cloven-hoofed animals (e.g. cattle, sheep, pigs) and can cause severe economic losses to the farm animal industries. The aim of this thesis was to quantify underlying mechanisms regarding transmission of FMDV. With data from past animal experiments we identified the factors which are associated with the amount of virus shed by infected animals and thus may be of importance for transmission of the virus. In an experimental study, the contribution of the environment on the transmission of FMDV was investigated by using a new mathematical model in which the contribution of the environment on transmission was incorporated. Roughly 44% of the transmission of FMDV occurred through the environment that was contaminated with se-excretions from FMDV infected animals. The role of the different species on the transmission of FMDV was investigated with a transmission study of FMDV between infected sheep and naïve cattle. Sheep were found to be less infectious than cattle but similarly susceptible. Using a so-called next-generation matrix, transmission of FMDV in mixed cattle-sheep populations (with different proportions of cattle and different proportions of vaccinated animals) was quantified and the effects of different vaccination strategies against FMDV were analysed. In mixed populations of cattle and sheep, transmission of FMDV is higher when more cattle are present. In populations with more than 14% cattle, targeting vaccination to cattle only can be sufficient to control FMDV.

    The results of this thesis show that transmission of FMDV can occur via a contaminated environment, (without animal presence) and that sheep seem to play a limited role in the transmission of FMDV. These results can be used to improve the control measures to prevent and control FMDV in different animal populations.

    Vaccination of cattle only is sufficient to stop FMDV transmission in mixed populations of sheep and cattle
    Bravo De Rueda, C. ; Dekker, A. ; Eblé, P.L. ; Jong, M. de - \ 2015
    Epidemiology and Infection 143 (2015)11. - ISSN 0950-2688 - p. 2279 - 2286.
    mouth-disease virus - basic reproduction ratio - between-pen transmission - emergency vaccination - infectious-diseases - quantification - eradication - protection - reduction - exposure
    We quantified the transmission of foot-and-mouth disease virus in mixed cattle-sheep populations and the effect of different vaccination strategies. The (partial) reproduction ratios (R) in groups of non-vaccinated and vaccinated cattle and/or sheep were estimated from (published) transmission experiments. A 4 × 4 next-generation matrix (NGM) was constructed using these estimates. The dominant eigenvalue of the NGM, the R for a mixed population, was determined for populations with different proportions of cattle and sheep and for three different vaccination strategies. The higher the proportion of cattle in a mixed cattle-sheep population, the higher the R for the mixed population. Therefore the impact of vaccination of the cattle is higher. After vaccination of all animals R = 0·1 independent of population composition. In mixed cattle-sheep populations with at least 14% of cattle, vaccination of cattle only is sufficient to reduce R to <1.
    Estimation of the transmission of foot-and-mouth disease virus from infected sheep to cattle
    Bravo De Rueda, C. ; Jong, M.C.M. de; Eble, P.L. ; Dekker, A. - \ 2014
    Veterinary Research 45 (2014). - ISSN 0928-4249 - 11 p.
    between-pen transmission - basic reproduction ratio - swine-fever virus - emergency vaccination - subclinical infection - within-pen - pigs - quantification - excretion - epidemic
    The quantitative role of sheep in the transmission of foot-and-mouth disease virus (FMDV) is not well known. To estimate the role of sheep in the transmission of FMDV, a direct contact transmission experiment with 10 groups of animals each consisting of 2 infected lambs and 1 contact calf was performed. Secretions and excretions (oral swabs, blood, urine, faeces and probang samples) from all animals were tested for the presence of FMDV by virus isolation (VI) and/or RT-PCR. Serum was tested for the presence of antibodies against FMDV. To estimate FMDV transmission, the VI, RT-PCR and serology results were used. The partial reproduction ratio R0 p i.e. the average number of new infections caused by one infected sheep introduced into a population of susceptible cattle, was estimated using either data of the whole infection chain of the experimental epidemics (the transient state method) or the final sizes of the experimental epidemics (the final size method). Using the transient state method, R0 p was estimated as 1.0 (95% CI 0.2 - 6.0) using virus isolation results and 1.4 (95% CI 0.3 - 8.0) using RT-PCR results. Using the final size method, R0 p was estimated as 0.9 (95% CI 0.2 - 3.0). Finally, R0 p was compared to the R0’s obtained in previous transmission studies with sheep or cattle only. This comparison showed that the infectivity of sheep is lower than that of cattle and that sheep and cattle are similarly susceptible to FMD. These results indicate that in a mixed population of sheep and cattle, sheep play a more limited role in the transmission of FMDV than cattle.
    Identification of factors associated with increased excretion of foot-and-mouth disease virus
    Bravo De Rueda, C. ; Dekker, A. ; Eble, P.L. ; Jong, M.C.M. de - \ 2014
    Preventive Veterinary Medicine 113 (2014)1. - ISSN 0167-5877 - p. 23 - 33.
    immune-responses - dairy-cows - transmission - vaccination - pigs - infection - quantification - epidemiology - calves - lambs
    We investigated which variables possibly influence the amount of foot-and-mouth disease virus (FMDV) shed in secretions and excretions by FMDV infected animals, as it is likely that the amount of FMDV shed is related to transmission risk. First, in a separate analysis of laboratory data, we showed that the total amount of FMDV in secretions and excretions from infected animals is highly correlated with maximum titres of FMDV. Next, we collected data from 32 published scientific articles in which FMDV infection experiments were described. The maximum titres of FMDV reported in different secretions and excretions (the response variable) and the experimental conditions in which they occurred (the explanatory variables), were recorded in a database and analyzed using multivariate regression models with and without random effects. In both types of models, maximum titres of FMDV were significantly (p <0.05) associated with types of secretions and excretions, animal species, stage of the disease and days post infection. These results can be used to prioritize biosecurity measures in contingency plans.
    Contribution of Foot-and-Mouth Disease virus contaminated environment to the transmisson of the disease in calves
    Bravo de Rueda Cabrera, Carla - \ 2012
    Contribution of Foot-and-Mouth Disease virus cantaminated environment to the transmission of the disease in calves
    Bravo de Rueda Cabrera, Carla - \ 2012
    A novel recombinant virus-like particle vaccine for prevention of porcine parvovirus-induced reproductive failure
    Antonis, A.F.G. ; Bruschke, C.J.M. ; Rueda, P. ; Maranga, L. ; Casal, J. ; Vela, C. ; Hilgers, L.A.T. ; Belt, P.B.G.M. ; Weerdmeester, K. ; Carrondo, M.J. ; Langeveld, J.P.M. - \ 2006
    Vaccine 24 (2006)26. - ISSN 0264-410X - p. 5481 - 5490.
    immune-responses - experimental-infection - baculovirus vectors - canine parvovirus - pregnant gilts - disease - pigs - coinfection - volunteers - adjuvants
    A novel vaccine against porcine parvovirus (PPV), composed of recombinant virus-like particles (PPV-VLPs) produced with the baculovirus expression vector system (BEVS) at industrial scale, was tested for its immunogenicity and protective potency. A formulation of submicrogram amounts of PPV-VLPs in a water-in-mineral oil adjuvant evoked high serum antibody titres in both guinea pigs, used as reference model, and target species, pigs. A single immunisation with 0.7 ¿g of this antigen yielded complete foetal protection against PPV infection after challenge with a virulent strain of this virus. Furthermore, also in the presence of mild adjuvants the protective action of these PPV-VLPs is excellent. This recombinant subunit vaccine overcomes some of the drawbacks of classical PPV vaccines
    A growth model of the cockle (Cerastoderma edule L.) tested in the Ooosterschelde estuary (The Netherlands)
    Rueda, J. ; Smaal, A.C. ; Scholten, H. - \ 2005
    Journal of Sea Research 54 (2005)4. - ISSN 1385-1101 - p. 276 - 298.
    bivalvia - groei - hydrobiologie - voortplanting - simulatiemodellen - nederland - oosterschelde - ecofysiologie - aquatische ecosystemen - bivalvia - growth - hydrobiology - reproduction - simulation models - netherlands - eastern scheldt - ecophysiology - aquatic ecosystems - mussel mytilus-edulis - gut-passage time - marennes-oleron - seasonal-variation - preingestive selection - ecophysiological model - seston concentration - variable conditions - particle selection - crassostrea-gigas
    The authors present an ecophysiological model of the bivalve Cerastoderma edule that simulates individual growth and reproduction under ambient conditions in temperature and food availability in the Oosterschelde estuary, SW Netherlands. The model contains feedback loops in the uptake and metabolism of food and in the partitioning of carbon to the internal state variables: somatic tissue, storage, organic shell matrix and gametes. The model was calibrated for 24 parameters, based on random distributions of parameter values. This procedure includes an estimate of confidence intervals of the output variables. The simulated growth of shell length and animal wet and dry weight reflected the observed values of growth in the field for the period 1993–1997. The model is a tool for the integration of ecophysiological knowledge of this species and also for carrying-capacity studies of shellfish culture and for environmental management of populations in estuarine and coastal areas
    We present an ecophysiological model of the bivalve Cerastoderma edule that Simulates individual growth and reproduction under ambient conditions in temperature and food availability in the Oosterschelde estuary, SW Netherlands. The model contains feedback loops in the uptake and metabolism of food and in the partitioning of carbon to the internal state variables: somatic tissue, storage, organic shell matrix and gametes. The model was calibrated for 24 parameters, based on random distributions of parameter values. This procedure includes an estimate of confidence intervals of the output variables. The simulated growth of shell length and animal wet and dry weight reflected the observed values of growth in the field for the period 1993-1997, The model is a tool for the integration of ecophysiological knowledge of this species and also for carrying-capacity studies of shellfish Culture and for environmental management of populations in estuarine and coastal areas. (c) 2005 Elsevier B.V. All rights reserved.
    Photoperiod affects growth, behaviour and stress variables in Clarias gariepinus
    Almazán Rueda, P. ; Helmond, A.T.M. van; Verreth, J.A.J. ; Schrama, J.W. - \ 2005
    Journal of Fish Biology 67 (2005)4. - ISSN 0022-1112 - p. 1029 - 1039.
    african catfish - burchell 1822 - diel rhythms - common carp - light - clariidae - survival - density - pisces - responses
    Short periods of light or no light (18D : 06L and 24D : 00L) resulted in an increased growth compared to extended periods of light (06D : 18L and 12D : 12L) in African catfish Clarias gariepinus. Fish under longer periods of light (12D : 12L and 18D : 06L) showed higher swimming activity, more aggression (injuries on the body) and higher lactate, free fatty acids and cortisol levels compared to those who were reared at shorter periods of light (24D : 00L and 18D : 06L). Feeding activity during light and dark periods in this experiment showed that C. gariepinus had both night and day feeding activities, with a preference to diurnal feeding in the 12D : 12L photoperiod. The results showed that light plays an important role in the African catfish behaviour and its wellbeing. As the hours of light increased during the 24 h cycle, data suggests that the fish were more stressed and aggressive, compared to those under a reduced number of light hours.
    Variation of the physiological energetics of the bivalve Spisula subtruncata (da Costa, 1778) within an annual cycle
    Rueda, J.L. ; Smaal, A.C. - \ 2004
    Journal of Experimental Marine Biology and Ecology 301 (2004)2. - ISSN 0022-0981 - p. 141 - 157.
    cerastoderma-edule bivalvia - suspension-feeding bivalves - mytilus-edulis - seasonal-variation - seston quantity - growth - mussel - reproduction - quality - spain
    Spisula subtruncata is an infaunal filter-feeding bivalve, which lives in shallow sandy bottoms (2¿20 m depth) from Norway to the Atlantic coasts of Morocco, including the Mediterranean Sea. Considering that fisheries of this species have become an important economic resource in some European countries (e.g. The Netherlands), it is of great interest to know the seasonal variation in its physiological energetics. For this purpose, individuals of S. subtruncata were collected and maintained under ambient temperature and seawater conditions of Dutch coastal waters. Physiological processes related to the acquisition and utilisation of energy (e.g. clearance rate [CR], absorption and oxygen uptake) were measured under ambient conditions of the period March 1999 to February 2000. Mean annual clearance and respiration rates (RR) were 0.99 l h¿1 and 0.23 ml O2 h¿1 for a standard individual of 250 mg. Values for both clearance and respiration rate were high during spring and summer and low during autumn and winter. Stepwise multiple regression analyses indicated a significant relationship of the clearance rate with temperature and particulate organic matter (POM), whereas respiration rate was significantly related to temperature, absorption rate (AR) of the animals and their reproductive condition. Absorption efficiency (AE) of the food was significantly related to food quality. Scope for growth (SFG) of S. subtruncata, as well as flesh weight of the animals, was high in summer and low in winter.
    Behavioural responses under different feeding methods and light regimes of the African catfish (Clarias gariepinus) juveniles
    Almazán Rueda, P. ; Schrama, J.W. ; Verreth, J.A.J. - \ 2004
    Aquaculture 231 (2004)1-4. - ISSN 0044-8486 - p. 347 - 359.
    growth - survival - clariidae - intensity - burchell - density - larvae
    Little is known about the behaviour of fish under culture conditions. Several factors may have a direct effect on fish behaviour and its variations during the day. This study assessed the effect of feeding method (continuous by self-feeders vs. twice a day hand-feeding), light intensity (15 vs. 150 1x) and photoperiod [continuous light vs. 12 h darkness and 12 h light (12D:12L)] on behaviour of juvenile African Catfish (Clarias gariepinus). Sixteen aquaria, each with 30 fish (average initial weight of 55 g) were used during a 6-week experimental period. Fish behaviour was recorded by direct observation. Fish were more active under hand-feeding regime than under self-feeding. Fish spent more time swimming under continuous light than under a 12D:12L. Furthermore, the time that fish spent swimming was higher at high light intensity (150 1x) than under low light intensity (15 1x). Aggression was affected by photoperiod and light intensity. Continuous light resulted in 41.6% more scars and wounds than the 1213:12L photoperiod, while high light intensity resulted in 2.46 times more scars and wounds than low light intensity. Fish that spent more time swimming and browsing were more aggressive, and they had more scars and wounds on the body. Fish under the hand-feeding method showed a higher activity during the morning compared to the afternoon. Fish also showed a higher activity before each meal (morning and afternoon meals) than afterwards. These activities were more evident during the mornings. The current study demonstrated that for juveniles of the African catfish, swimming activity and agonistic behaviour are strongly affected by husbandry conditions. (C) 2004 Elsevier B.V. All rights reserved.
    Towards assessment of welfare in Africal catfish, Clarias gariepinus: the first step
    Almazán Rueda, P. - \ 2004
    Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Johan Schrama. - [S.l.] : S.n. - ISBN 9789058089410 - 152
    clarias gariepinus - diergedrag - dierenwelzijn - stress - stressreactie - visvoeding - groei - lichtregiem - bezettingsdichtheid - bloedanalyse - visteelt - aquacultuur - clarias gariepinus - animal behaviour - animal welfare - stress - stress response - fish feeding - growth - light regime - stocking density - blood analysis - fish culture - aquaculture
    Physiological response of Spisula subtruncata (da Costa, 1778) to different seston quantity and quality
    Rueda, J.L. ; Smaal, A.C. - \ 2002
    Hydrobiologia 475 (2002)1. - ISSN 0018-8158 - p. 505 - 511.
    suspension-feeding bivalves - cerastoderma-edule l - suspended bottom material - mytilus-edulis - pinctada-margaritifera - particle selection - perna-viridis - body-size - absorption - behavior
    Individuals of the bivalve Spisula subtruncata were fed a mixed diet comprising of sea water enriched with the diatom Phaeodactylum tricornutum and ashed silt within a range of concentrations, simulating natural conditions above pseudofaeces threshold. The designed ranges for total particulate matter were between 10 and 30 mg l¿1and organic content of seston 15¿40%. Filtration rate, rejection rate, ingestion rate and absorption rate were measured at those different conditions. Filtration rate and rejection rate were significantly correlated to total particulate matter and percentage of organic matter, with higher rates at higher values of total particulate matter and lower values of percentage organic matter. Ingestion rate was maintained at similar levels in all the treatments and organic enrichment of the ingested food occurred due to preingestive selection of the filtered material. A differential absorption rate occurred at different levels of organic matter in the diet with high rates at high values of the organic content of the diet. S. subtruncata showed different physiological responses to changes of the food conditions: (1) Increase of pseudofaeces production at increasing levels of particulate matter, (2) preingestive selection of organic material which enriched the organic fraction of ingested food, (3) stabilized ingestion rate and (4) increase of the absorption rate at high organic levels of the seston
    Selective ingestion of pelagic versus benthic algae by the cockle Cerastoderma edule (Linne, 1758)
    Rueda, J.L. ; Smaal, A.C. - \ 2002
    Journal of Shellfish Research 21 (2002)2. - ISSN 0730-8000 - p. 619 - 625.
    The pre-ingestive selection of microphytobenthic algae by the cockle Cerastoderma edule was studied in comparison with diets containing the pelagic diatom Phaeodactylum tricornutum. Treatments with the different diets covered a range of seston concentrations and organic content similar to field conditions. Rejection rates of C. edule exposed to the different treatments were significantly correlated with the concentration of total particulate matter. No significant differences in total rejection rates were found between pelagic and benthic diets. Organic rejection rate was significantly correlated with particulate organic matter of the treatments and no significant differences were found between both diets. Selection efficiency was significantly correlated with particulate organic matter concentration in both diets and no significant differences were found between the diets. Analysis of the pseudofeces composition by flow cytometry from cockles exposed to a mixed diet of microphytobenthic algae and P. tricornutum, showed a preferential ingestion of the pelagic diatom. Benthic species, such as small pennates and Navicula sp., were preferentially ingested in comparison to larger microphytobenthic species. The largest microphytobenthic species, Cylindrotheca sp., was significantly rejected. In general, C. edule is an opportunistic filter feeder that takes advantage of both pelagic and benthic algal cells.
    Group size and space availability affect behaviour and stress parameters in African catfish (Clarias gariepinus)
    Almazan-Rueda, P. ; Schrama, J.W. ; Verreth, J.A.J. - \ 2002
    In: Proceedings of the 36th International Congress of the International Society of Applied Ethology Wageningen : Ponsen en Looijen - p. 1 - 119.
    Large scale production and downstream processing of a recombinant porcine parvovirus vaccine
    Maranga, L. ; Rueda, P. ; Antonis, A.F.G. ; Vela, C. ; Langeveld, J.P.M. ; Casal, J.I. ; Carrondo, M.J.T. - \ 2002
    Applied Microbiology and Biotechnology 59 (2002). - ISSN 0175-7598 - p. 45 - 50.
    Porcine parvovirus (PPV) virus-like particles (VLPs) constitute a potential vaccine for prevention of parvovirus-induced reproductive failure in gilts. Here we report the development of a large scale (25 l) production process for PPV-VLPs with baculovirus-infected insect cells. A low multiplicity of infection (MOI) strategy was efficiently applied avoiding the use of an extra baculovirus expansion step. The optimal harvest time was defined at 120 h post-infection at the MOI used, with the cell concentration at infection being 1.52106 cells/ml. An efficient purification scheme using centrifugation, precipitation and ultrafiltration/diafiltration as stepwise unit operations was developed. The global yield of the downstream process was 68%. Baculovirus inactivation with Triton X-100 was successfully integrated into the purification scheme without an increase in the number of process stages. Immunogenicity of the PPV-VLPs tested in guinea pigs was similar to highly purified reference material produced from cells cultured in the presence of serum-containing medium. These results indicate the feasibility of industrial scale production of PPV-VLPs in the baculovirus system, safety of the product, and the potency of the product for vaccine application.
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