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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Dairy products and the risk of stroke and coronary heart disease: the Rotterdam Study
Praagman, J. ; Franco, O.H. ; Ikram, M.A. ; Soedamah-Muthu, S.S. ; Engberink, M.F. ; Rooij, F.J.A. van; Hofman, A. ; Geleijnse, J.M. - \ 2015
European Journal of Nutrition 54 (2015)6. - ISSN 1436-6207 - p. 981 - 990.
dietary-protein sources - cardiovascular-disease - consumption - population - women - cohort - food - metaanalysis - definitions - death
Purpose We examined whether consumption of total dairy and dairy subgroups was related to incident stroke and coronary heart disease (CHD) in a general older Dutch population. Methods The study involved 4,235 participants of the Rotterdam Study aged 55 and over who were free of cardiovascular disease (CVD) and diabetes at baseline (1990–1993). Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) for the intake of total dairy and dairy subgroups in relation to incident CVD events. Results Median intake of total dairy was 397 g/day, which mainly comprised low-fat dairy products (median intake of 247 g/day). During a median follow-up time of 17.3 years, 564 strokes (182 fatal) and 567 CHD events (350 fatal) occurred. Total dairy, milk, low-fat dairy, and fermented dairy were not significantly related to incident stroke or fatal stroke (p > 0.2 for upper vs. lower intake categories). High-fat dairy was significantly inversely related to fatal stroke (HR of 0.88 per 100 g/day; 95 % CI 0.79, 0.99), but not to incident stroke (HR of 0.96 per 100 g/day; 95 % CI 0.90, 1.02). Total dairy or dairy subgroups were not significantly related to incident CHD or fatal CHD (HRs between 0.98 and 1.05 per 100 g/day, all p > 0.35). Conclusions In this long-term follow-up study of older Dutch subjects, total dairy consumption or the intake of specific dairy products was not related to the occurrence of CVD events. The observed inverse association between high-fat dairy and fatal stroke warrants confirmation in other studies.
Characterization of apoptosis in PER.C6® batch and perfusion cultures
Mercier, S.M. ; Diepenbroek, B. ; Martens, D.E. ; Wijffels, R.H. ; Streefland, M. - \ 2015
Biotechnology and Bioengineering 112 (2015)3. - ISSN 0006-3592 - p. 569 - 578.
hamster ovary cells - high-level expression - flow-cytometry - line per.c6 - death - adenovirus - dna - vaccine - gene - manufacture
Preventing or delaying cell death is a challenge in mammalian cell cultures for the development and optimization of production processes for biopharmaceuticals. Cell cultures need to be maintained highly viable for extended times in order to reach maximum production yields. Moreover, programmed cell death through apoptosis is often believed to occur without being detected by classical viability measurements. In this study, we characterized cell death in PER.C6® batch and perfusion cultures using three flow cytometry techniques measuring different steps of the apoptosis cascade: DNA fragmentation, caspases activation and phosphatidylserine externalization. We showed that apoptosis is the main pathway of PER.C6® cell death in batch cultures after depletion of main carbon sources. In high cell density perfusion cultures fed at a constant specific perfusion rate, both high viability and very limited apoptosis were observed. When extending this perfusion process far beyond standard operations, cultures were exposed to suboptimal process conditions, which resulted in an increase of apoptotic cell death. Moreover, we showed that the reference viability measurement using trypan blue exclusion properly assesses the level of cell death in PER.C6® cultures. This study is a first step in understanding the mechanisms of PER.C6® cell death, which will be helpful to support applications of the cell line.
Glycemic control and all-cause mortality risk in type 1 diabetes patients: the EURODIAB prospective complications study
Schoenaker, D.A.J.M. ; Simon, D. ; Chaturvedi, N. ; Fuller, J.H. ; Soedamah-Muthu, S.S. - \ 2014
Journal of Clinical Endocrinology and Metabolism 99 (2014)3. - ISSN 0021-972X - p. 800 - 807.
vascular complications - cardiovascular-disease - severe hypoglycemia - hba(1c) - trials - cohort - accord - rates - death - a1c
Context: Glycemic targets and the benefit of intensive glucose control are currently under debate because intensive glycemic control has been suggested to have negative effects on mortality risk in type 2 diabetes patients. Objective: We examined the association between glycated hemoglobin (HbA1c) and all-cause mortality in patients with type 1 diabetes mellitus. Design, Setting, and Patients: A clinic-based prospective cohort study was performed in 2764 European patients with type 1 diabetes aged 15–60 years enrolled in the EURODIAB Prospective Complications Study. Outcome Measure: Possible nonlinearity of the association between HbA1c and all-cause mortality was examined using multivariable restricted cubic spline regression using three (at HbA1c 5.6%, 8.1%, and 11.8%) and five knots (additionally at HbA1c 7.1% and 9.5%). Mortality data were collected approximately 7 years after baseline examination. Results: HbA1c was related to all-cause mortality in a nonlinear manner after adjustment for age and sex. All-cause mortality risk was increased at both low (5.6%) and high (11.8%) HbA1c compared with the reference (median HbA1c: 8.1%) following a U-shaped association [P overall effect = .008 and .04, P nonlinearity = .03 and .11 (three and five knots, respectively)]. Conclusions: Results from our study in type 1 diabetes patients suggest that target HbA1c below a certain threshold may not be appropriate in this population. We recognize that these low HbA1c levels may be related to anemia, renal insufficiency, infection, or other factors not available in our database. If our data are confirmed, the potential mechanisms underlying this increased mortality risk among those with low HbA1c will need further study.
Circadian rhythms in the cell cycle and biomass composition of Neochloris oleoabundans under nitrogen limitation
Winter, L. de; Schepers, L.W. ; Cuaresma Franco, M. ; Barbosa, M.J. ; Martens, D.E. ; Wijffels, R.H. - \ 2014
Journal of Biotechnology 187 (2014). - ISSN 0168-1656 - p. 25 - 33.
chlamydomonas-reinhardtii - nutrient starvation - microalgae - division - growth - accumulation - quadricauda - clock - death
The circadian clock schedules processes in microalgae cells at suitable times in the day/night cycle. To gain knowledge about these biological time schedules, Neochloris oleoabundans was grown under constant light conditions and nitrogen limitation. Under these constant conditions, the only variable was the circadian clock. The results were compared to previous work done under nitrogen-replete conditions, in order to determine the effect of N-limitation on circadian rhythms in the cell cycle and biomass composition of N. oleoabundans. The circadian clock was not affected by nitrogen-limitation, and cell division was timed in the natural night, despite of constant light conditions. However, because of nitrogen-limitation, not the entire population was able to divide every day. Two subpopulations were observed, which divided alternately every other day. This caused oscillations in biomass yield and composition. Starch and total fatty acids (TFA) were accumulated during the day. Also, fatty acid composition changed during the cell cycle. Neutral lipids were built up during the day, especially in cells that were arrested in their cell cycle (G2 and G3). These findings give insight in the influence of circadian rhythms on the cell cycle and biomass composition.
What controls tropical forst architecture? Testing environmental, structural and floristic drivers
Banin, L. ; Feldpausch, T.R. ; Philips, O.L. ; Baker, T.R. ; Lloyd, J. ; Affum-Baffoe, K. ; Arets, E.J.M.M. - \ 2012
Global Ecology and Biogeography 21 (2012)12. - ISSN 1466-822X - p. 1179 - 1190.
rain-forest - tree height - mechanical constraints - aboveground biomass - life-history - allometry - growth - mortality - climate - death
Aim To test the extent to which the vertical structure of tropical forests is determined by environment, forest structure or biogeographical history. Location Pan-tropical. Methods Using height and diameter data from 20,497 trees in 112 non-contiguous plots, asymptotic maximum height (H AM) and height–diameter relationships were computed with nonlinear mixed effects (NLME) models to: (1) test for environmental and structural causes of differences among plots, and (2) test if there were continental differences once environment and structure were accounted for; persistence of differences may imply the importance of biogeography for vertical forest structure. NLME analyses for floristic subsets of data (only/excluding Fabaceae and only/excluding Dipterocarpaceae individuals) were used to examine whether family-level patterns revealed biogeographical explanations of cross-continental differences. Results H AM and allometry were significantly different amongst continents. H AM was greatest in Asian forests (58.3 ± 7.5¿m, 95% CI), followed by forests in Africa (45.1 ± 2.6¿m), America (35.8 ± 6.0¿m) and Australia (35.0 ± 7.4¿m), and height–diameter relationships varied similarly; for a given diameter, stems were tallest in Asia, followed by Africa, America and Australia. Precipitation seasonality, basal area, stem density, solar radiation and wood density each explained some variation in allometry and H AM yet continental differences persisted even after these were accounted for. Analyses using floristic subsets showed that significant continental differences in H AM and allometry persisted in all cases. Main conclusions Tree allometry and maximum height are altered by environmental conditions, forest structure and wood density. Yet, even after accounting for these, tropical forest architecture varies significantly from continent to continent. The greater stature of tropical forests in Asia is not directly determined by the dominance of the family Dipterocarpaceae, as on average non-dipterocarps are equally tall. We hypothesise that dominant large-statured families create conditions in which only tall species can compete, thus perpetuating a forest dominated by tall individuals from diverse families.
Cell cycle analysis of primary sponge cell cultures
Schippers, K.J. ; Martens, D.E. ; Pomponi, S.A. ; Wijffels, R.H. - \ 2011
In Vitro Cellular & Developmental Biology. Animal 47 (2011)4. - ISSN 1071-2690 - p. 302 - 311.
marine sponges - death - porifera - growth - sea
Proliferation of sponge cells is generally measured via cell counts or viability assays. However, more insight into the proliferative state of a sponge cell population can be obtained from the distribution of the cells over the different phases of the cell cycle. Cell cycle distribution of sponge cells was measured via flow cytometry after staining the DNA with propidium iodide. The five sponges studied in this paper all showed a large fraction of cells in G1/G0 compared to G2/M and S, indicating that cells were not actively dividing. In addition, some sponges also showed a large apoptotic fraction, indicating cell death. Additional apoptosis measurements, based on caspase activity, showed that harvesting and dissociation of sponge tissue to initiate a primary cell culture was directly correlated with an increase in apoptotic cells. This indicates that for the development of cell cultures, more attention should be given to harvesting, dissociation, and quality of starting material. Finally, cultivation conditions used were ineffective for proliferation, since after 2 d of cultivating Haliclona oculata cells, most cells shifted towards the apoptotic fraction, indicating that cells were dying. For development of in vitro sponge cell cultures, flow cytometric cell cycle analysis is a useful method to assess the proliferative state of a sponge cell culture and can be used to validate improvements in harvesting and dissociation, to select sponges with good proliferative capacities and to study the influence of culture conditions for stimulating cell growth.
Een einde aan dit einde
Bijleveld, H. ; Woelders, H. - \ 2011
De Pluimveehouderij 2011 (2011). - ISSN 0166-8250 - p. 20 - 22.
pluimveehouderij - jonge dieren - dierenwelzijn - dood - hanen - vleeskuikens - kuikenproductie - pluimvee - hennen - dierlijke productie - poultry farming - young animals - animal welfare - death - cocks - broilers - chick production - poultry - hens - animal production
Het doden van eendagshaantjes heeft de afgelopen jaren meer en meer maatschappelijke en politieke weerstand opgeroepen. Wageningen UR onderzoekt enkele alternatieven.
Bijen en bestuiving BO-12.03-007
Kogel, W.J. de - \ 2011
bijenhouderij - varroa - mijten - bijenziekten - dood - wilde bijenvolken - bijenvolken om te fokken - bijensterfte - beekeeping - mites - bee diseases - death - wild honey bee colonies - nucleus honey bee colonies - bee mortality
De bijenhouderij in Nederland draagt via bestuiving in belangrijke mate bij aan de brutoproductie van land- en tuinbouw. De geschatte bijdrage door bestuiving bedraagt >€ 1 miljard/jaar. Daarnaast is er een grote niet-gekwantificeerde waarde voor de natuur: naast de door imkers gehouden honingbijen wordt door diverse soorten wilde bijen en andere insecten voor bestuiving gezorgd. Sinds de tachtiger jaren is de bijenhouderij bijna wereldwijd geconfronteerd met de invasieve parasiet varroa. Behalve door de varroamijt wordt de imkerij nog door andere zaken bedreigd. Dit leidde de laatste jaren tot meldingen van de sterfte van bijenvolken. Dit veroorzaakt onrust bij publiek, aandacht in de media en vragen in de Tweede Kamer. Er is behoefte aan duidelijkheid over de omvang en oorzaken van de bijensterfte. Dit moet leiden tot wetenschappelijk onderbouwde uitspraken en maatregelen om honingbijen en wilde bestuivers voor deze sterfte te behoeden. In het onderzoeksproject BIJ-1 wordt onderzocht in welke mate er sprake is van bijensterfte in Nederland en wat de mogelijke oorzaken en oplossingsrichtingen zijn
Een haan-of-ei kwestie. Een vergelijkend ethisch onderzoek tussen het doden van haantjes (in legpluimveehouderij) direct na uitkomen of embryonale fase
Jochemsen, H. ; Rademaker, C. - \ 2010
Wageningen : Bijzondere leerstoelgroep Christelijke Filosofie - 23
dierenwelzijn - pluimveehouderij - hanen - hennen - dood - ethiek - dierlijke productie - pluimvee - diergezondheid - animal welfare - poultry farming - cocks - hens - death - ethics - animal production - poultry - animal health
In de legpluimveehouderij worden voortdurend hennen opgefokt ten behoeve van handhaving van de veestapel in de fase van leg. In het productieproces worden evenveel haantjes als hennen geboren. De haantjes zijn (economisch) overtollig. Direct na de geboorte worden de kuikens gesekst en de haantjes worden gedood en afgevoerd. Het gaat in Nederland om omstreeks 45 miljoen haantjes per jaar. Aan dit proces zit naast een economische kant - hoe eerder de haantjes verwijderd kunnen worden, hoe minder op dit punt kosten worden gemaakt - ook een ethische kant. Dit betreft de vraag of het doden en als diervoeder afvoeren van haantjes onmiddellijk na het uitkomen ethisch is te verantwoorden.
Biggensterfte in een biologisch kraamhok
Vermeer, Herman - \ 2010
organic farming - pig farming - piglets - farrowing - farrowing pens - death - animal health - litter size - care of animals - hokkenpens
Caspase inhibitors affect the kinetics and dimensions of tracheary elements in xylogenic Zinnia (Zinnia elegans) cell cultures
Twumasi, P. ; Iakimova, E.T. ; Qian, T. ; Ieperen, W. van; Schel, J.H.N. ; Emons, A.M.C. ; Kooten, O. van; Woltering, E.J. - \ 2010
BMC Plant Biology 10 (2010). - ISSN 1471-2229
tomato suspension cells - mesophyll-cells - hypersensitive response - vascular development - dna fragmentation - serine proteases - plant caspases - nuclear-dna - death - differentiation
BACKGROUND: The xylem vascular system is composed of fused dead, hollow cells called tracheary elements (TEs) that originate through trans-differentiation of root and shoot cambium cells. TEs undergo autolysis as they differentiate and mature. The final stage of the formation of TEs in plants is the death of the involved cells, a process showing some similarities to programmed cell death (PCD) in animal systems. Plant proteases with functional similarity to proteases involved in mammalian apoptotic cell death (caspases) are suggested as an integral part of the core mechanism of most PCD responses in plants, but participation of plant caspase-like proteases in TE PCD has not yet been documented. RESULTS: Confocal microscopic images revealed the consecutive stages of TE formation in Zinnia cells during trans-differentiation. Application of the caspase inhibitors Z-Asp-CH2-DCB, Ac-YVAD-CMK and Ac-DEVD-CHO affected the kinetics of formation and the dimensions of the TEs resulting in a significant delay of TE formation, production of larger TEs and in elimination of the 'two-wave' pattern of TE production. DNA breakdown and appearance of TUNEL-positive nuclei was observed in xylogenic cultures and this was suppressed in the presence of caspase inhibitors. CONCLUSIONS: To the best of our knowledge this is the first report showing that caspase inhibitors can modulate the process of trans-differentiation in Zinnia xylogenic cell cultures. As caspase inhibitors are closely associated with cell death inhibition in a variety of plant systems, this suggests that the altered TE formation results from suppression of PCD. The findings presented here are a first step towards the use of appropriate PCD signalling modulators or related molecular genetic strategies to improve the hydraulic properties of xylem vessels in favour of the quality and shelf life of plants or plant parts
Marine n-3 fatty acids, fish consumption, and the 10-year risk of fatal and nonfatal coronary heart disease in a large population of Dutch adults with a low fish intake
Goede, J. de; Geleijnse, J.M. ; Boer, J.M.A. ; Kromhout, D. ; Verschuren, W.M.M. - \ 2010
The Journal of Nutrition 140 (2010)5. - ISSN 0022-3166 - p. 1023 - 1028.
food frequency questionnaire - relative validity - myocardial-infarction - mortality - cohort - reproducibility - netherlands - health - death - oil
We assessed the dose-response relations within a low range of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and fish intake on fatal coronary heart disease (CHD) and nonfatal myocardial infarction (MI). In a Dutch population-based cohort study, EPA+DHA and fish intake were assessed at baseline among 21,342 participants aged 20–65 y with no history of MI or stroke. Hazard ratios were calculated with Cox proportional-hazard models. During 9–14 y of follow-up (mean 11.3 y), 647 participants (3%) died, of which 82 of CHD. Fatal CHD mainly comprised MI (64 case). In total, 252 participants survived an MI. Median intake in quartiles of EPA+DHA were 40, 84, 151, and 234 mg/d. Medians of fish consumption in quartiles were 1.1, 4.2, 10.7, and 17.3 g/d. Compared with the lowest quartile of EPA+DHA, participants in the top quartile had a 49% lower risk of fatal CHD (95% CI: 6–73%) and a 62% lower risk of fatal MI (95% CI: 23–81%). We observed inverse dose-response relations for EPA+DHA intake and fatal CHD (P-trend = 0.05) and fatal MI (P-trend = 0.01). Results were similar for fish consumption. Nonfatal MI was not associated with EPA+DHA or fish intake. In conclusion, in populations with a low fish consumption, EPA+DHA and fish may lower fatal CHD and MI risk in a dose-responsive manner. Low intakes of EPA+DHA or fish do not seem to protect against nonfatal MI.
Extracts of Medicinal Mushrooms Agaricus bisporus and Phellinus linteus Induce Proapoptotic Effects in the Human Leukemia Cell Line K562
Shnyreva, A.V. ; Song, W. ; Griensven, L.J.L.D. van - \ 2010
International Journal of Medicinal Mushrooms 12 (2010)2. - ISSN 1521-9437 - p. 167 - 175.
nf-kappa-b - interferon-gamma - apoptosis - mechanisms - expression - death - pcr
We have studied the effects of Agaricus bisporus and Phellinus linteus ethanol extracts on transcriptional regulation of genes involved in cytokine release and apoptosis in the human leukemia cell line K562. In particular, we applied quantitative real-time PCR (Q-PCR) assays to monitor alterations of gene expression for the following genes: Bcl-2, Casp-9, NF-¿B, TNF-a, IFN-¿, and IL-10. We found stronger proapoptotic activity for the Ph. linteus alcohol extract on K562 cells than for the A. bisporus extract: 4.4- and 2.2-fold increase of Bcl-2 and Casp-9 transcripts. Mushroom alcohol extracts are suggested to exert their effects on tumor cells via the induction of apoptosis. K562 leukemia cells were shown to be most responsive to the transcriptional induction of tumor necrosis factor TNF-a when stimulated with IFN-¿ and then treated with Ph. linteus alcohol extract: up to a 4.5-fold increase. Treatment of K562 cells with A. bisporus extract promoted transcription of the cytokine gene IL-10
Respiratory function and other biological risk factors for completed suicide: 40 years of follow-up of European cohorts of the Seven Countries Study
Giltay, E.J. ; Zitman, F.G. ; Menotti, A. ; Nissinen, A. ; Jacobs, D.R. ; Adachi, H. ; Kafatos, A. ; Kromhout, D. - \ 2010
Journal of Affective Disorders 120 (2010)1-3. - ISSN 0165-0327 - p. 249 - 253.
body-mass index - serum-cholesterol - united-states - lung-function - men - association - mortality - height - death - ideation
Background - Prospective cohort studies on biological risk factors of completed suicide are scarce. We aimed to test which biological risk factors independently identify subjects at increased risk of suicidal death. Methods - In the prospective cohort of the Seven Countries Study, 5,321 middle-aged men from Finland, Serbia, Italy, and Greece were included. Completed suicide (ICD-8 codes E950-959) was assessed during 40 years of follow-up. Biological cardiovascular risk factors (including forced vital capacity [FVC] and height) were tested for their role as predictors in multivariable Cox models stratified by country. Results - There were 4518 deaths during follow-up, with 64 from suicide (1.4%). In univariable models, only FVC and height were strongly inversely related with suicide. Socio-economic status and being unmarried were potential confounders. In multivariable models taking these confounders into account, both a low FVC (0.30 for top vs. lowest quartile; 95% CI: 0.12–0.76; P = 0.006 for trend) and a low FVC/height ratio (0.37 for top vs. lowest quartile; 95% CI: 0.17–0.82; P = 0.004 for trend) were strongly inversely related with completed suicide. Limitations - Information on proximal causes, such as prior suicidal ideation, emotional distress and depression, was lacking at baseline. Conclusions - Poor respiratory function in middle-aged men was an independent risk factor for completed suicide
Praktijkervaringen lelies koken met voor- en nawarmte
Kok, B.J. ; Aanholt, J.T.M. van - \ 2010
BloembollenVisie 2010 (2010)184. - ISSN 1571-5558 - p. 22 - 23.
bloembollen - lelies - cultivars - hybriden - heetwaterbehandeling - warmtebehandeling - steriliseren - mijten - dood - ornamental bulbs - lilies - hybrids - hot water treatment - heat treatment - sterilizing - mites - death
In 2009 hebben 10 lelietelers de nieuwe kookbehandeling bij 41°C in combinatie met voor- en nawarmte in 27 leliecultivars uit de groep van de Oriëntals en de LA-hybriden. De resultaten waren positief
Validity of coronary heart diseases and heart failure based on hospital discharge and mortality data in the Netherlands using the cardiovascular registry Maastricht cohort study
Merry, A.H. ; Boer, J.M. ; Schouten, L.J. ; Feskens, E.J.M. ; Verschuren, W.M. ; Gorgels, A.P. ; Brandt, P.A. van den - \ 2009
European Journal of Epidemiology 24 (2009)5. - ISSN 0393-2990 - p. 237 - 247.
acute myocardial-infarction - routine mortality - finland - statistics - diagnosis - project - trends - death - morbidity - community
Incidence rates of cardiovascular diseases are often estimated by linkage to hospital discharge and mortality registries. The validity depends on the quality of the registries and the linkage. Therefore, we validated incidence rates of coronary heart disease (CHD), acute myocardial infarction, unstable angina pectoris, and heart failure, estimated by this method, against the disease registry of the cardiovascular registry Maastricht cohort study. The cohort consists of 21,148 persons, born between 1927 and 1977, who were randomly sampled from Maastricht and surrounding communities in 1987–1997. Incident cases were identified by linkage to the Netherlands causes of death registry and either the hospital discharge registry (HDR) or the cardiology information system (CIS) of the University Hospital Maastricht. Sensitivities and positive predictive values were calculated using the CIS-based registry as gold standard. Relatively high sensitivities and positive predictive values were found for CHD (72 and 91%, respectively) and acute myocardial infarction (84 and 97%, respectively). These values were considerably lower for unstable angina pectoris (53 and 78%, respectively) and heart failure (43 and 80%, respectively). A substantial number of cases (14–47%) were found only in the CIS-based registry, because they were missed or miscoded in the HDR-based registry. As a consequence, the incidence rates in the HDR-based registry were considerably lower than in the CIS-based registry, especially for unstable angina pectoris and heart failure. Incidence rates based on hospital discharge and mortality data may underestimate the true incidence rates, especially for unstable angina pectoris and heart failure
Kweker wil graag zijn paling visvriendelijk doden
Noorduyn, L. - \ 2009
Syscope Magazine 2009 (2009)23. - p. 8 - 9.
palingteelt - palingen - dood - dierenwelzijn - mechanische methoden - innovaties - elektrisch verdoven - systeeminnovatie - eel culture - eels - death - animal welfare - mechanical methods - innovations - electronarcosis - system innovation
Paling doden is geen leuk karwei. Palingkweker Johan Meulendijks zegt er nooit aan te wennen. Hij werkte dan ook vol overgave mee aan een manier om de vissen diervriendelijk te doden. Nu is het wachten op het definitieve apparaat
Cell kinetics of the marine sponge Halisarca caerulea reveal rapid cell turnover and shedding
Goeij, J.M. de; Kluijver, A. de; Duyl, F.C. van; Vacelet, J. ; Wijffels, R.H. ; Goeij, A.F.P.M. de; Cleutjens, J.P.M. ; Schutte, B. - \ 2009
Journal of Experimental Biology 212 (2009)23. - ISSN 0022-0949 - p. 3892 - 3900.
organic-carbon doc - telomerase activity - suspension feeders - hydra-attenuata - cycle kinetics - iv collagen - porifera - demospongiae - removal - death
This study reveals the peculiar in vivo cell kinetics and cell turnover of the marine sponge Halisarca caerulea under steady-state conditions. The tropical coral reef sponge shows an extremely high proliferation activity, a short cell cycle duration and massive cell shedding. Cell turnover is predominantly confined to a single cell population, i.e. the choanocytes, and in this process apoptosis only plays a minor role. To our knowledge, such fast cell kinetics under steady-state conditions, with high turnover by shedding in the absence of apoptosis, has not been observed previously in any other multicellular organism. The duration of the cell cycle in vivo resembles that of unicellular organisms in culture. Morphological and histochemical studies demonstrate compartmentalization of choanocytes in the sponge tissue, which corresponds well with its remarkable cellular kinetics. Coral reef cavity sponges, like H. caerulea, inhabit low nutrient tropical waters, forcing these organisms to filter large volumes of water and to capture the few nutrients efficiently. Under these oligotrophic conditions, a high cell turnover may be considered as a very useful strategy, preventing permanent damage to the sponge by environmental stress. Halisarca caerulea maintains its body mass and keeps its food uptake system up to date by constantly renewing its filter system. We conclude that studies on cell kinetics and functional morphology provide new and essential information on the growth characteristics and the regulation of sponge growth in vivo as well as in vitro and the role of choanocytes in tissue homeostasis
Establishing in vitro Zinnia elegans cell suspension culture with high tracheary elements differentiation
Twumasi, P. ; Schel, J.H.N. ; Ieperen, W. van; Woltering, E.J. ; Emons, A.M.C. - \ 2009
Cell Biology International 33 (2009)4. - ISSN 1065-6995 - p. 524 - 533.
cellulose synthesis - death - mesophyll - lignification - xylogenesis - involvement - apoptosis - xylem
The Zinnia elegans mesophyll cell culture is a useful system for xylogenesis studies. The system is associated with highly synchronous tracheary element (TE) differentiation, making it more suitable for molecular studies requiring larger amounts of molecular isolates, such as mRNA and proteins and for studying cellulose synthesis. There is, however, the problem of non-uniformity and significant variations in the yields of TEs (%TE). One possible cause for this variability in the %TE could be the lack of a standardized experimental protocol in various research laboratories for establishing the Zinnia culture. Mesophyll cells isolated from the first true leaves of Z. elegans var Envy seedlings of approximately 14 days old were cultured in vitro and differentiated into TEs. The xylogenic culture medium was supplied with 1 mg/l each of benzylaminopurine (BA) and ¿-naphthalene acetic acid (NAA). Application of this improved culture method resulted in stable and reproducible amounts of TE as high as 76% in the Zinnia culture. The increase was mainly due to conditioning of the mesophyll cell culture and adjustments of the phytohormonal balance in the cultures. Also, certain biochemical and cytological methods have been shown to reliably monitor progress of TE differentiation. We conclude that, with the adoption of current improvement in the xylogenic Z. elegans culture, higher amounts of tracheary elements can be produced. This successful outcome raises the potential of the Zinnia system as a suitable model for cellulose and xylogenesis research.
Improved postthaw viability and in vitro functionality of peripheral blood hematopoietic progenitor cells after cryopreservation with a theoretically optimized freezing curve
Tijssen, M.R. ; Woelders, H. ; Vries - van Rossen, A. de; Schoot, C. van der; Voermans, C. ; Lagerberg, J.W.M. - \ 2008
Transfusion 48 (2008)5. - ISSN 0041-1132 - p. 893 - 901.
cd34(+) cells - clinical toxicity - stem-cells - apoptosis - permeability - infusion - grafts - marrow - death
The freezing curve currently used for the cryopreservation of peripheral blood stem cell transplants (PBSCTs) has been determined empirically. Although the use of cryopreserved PBSCTs is successful and usually leads to rapid hematopoietic recovery, the freeze-thawing process is known to induce a significant degree of cell death. Furthermore, the infusion of dimethyl sulfoxide (DMSO), used to protect the cells against damage induced by freezing, can cause morbidity. Therefore, optimizing the current cryopreservation protocol (with 10% DMSO and a slow linear cooling curve) with theoretically optimized freezing curves and a lower DMSO concentration might improve the recovery after transplantation
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