Integrale diergezondheid: beheersing van leverbot

Leverbotinfecties zijn in toenemende mate een knelpunt in de diergezondheid van melkvee en andere herkauwers. Door de complexe infectiecyclus, weinig inzetbare geneesmiddelen, geringe beschikbare diagnostiek en incomplete terugkoppeling van informatie (afkeur lever), kan leverbot de gezondheid negatief beïnvloeden waardoor ook vaak productieverliezen kunnen optreden. Voor vee dat melk produceert voor menselijke consumptie zijn nagenoeg geen middelen meer toegestaan om leverbot te bestrijden. Resistentie tegen de beschikbare middelen, indien diercategorieën wel behandeld mogen worden, neemt toe. Veehouders hebben behoefte aan kennis en mogelijkheden ter preventie van leverbotbesmettingen, en aan alternatieven voor een effectieve bestrijding van de leverbot en het voorkomen van resistentie tegen leverbotmiddelen. Vanuit deze problematiek gezien hebben veehouders behoefte aan een instrument waarmee ze de leverbotsituatie op hun bedrijf in kaart kunnen brengen en aan handelingsperspectief om de situatie te verbeteren. Dit project heeft een concept instrument ontwikkeld om de leverbotstatus op het bedrijf te beoordelen, de risicofactoren in kaart te brengen en mogelijke preventieve maatregelen aan te geven. Dit onderzoek is uitgevoerd door Wageningen UR Livestock Research in samenwerking met het Louis Bolk Instituut en orgANIMprove, in opdracht van en gefinancierd door het Ministerie van Economische Zaken, in het kader van het Beleidsondersteunend onderzoek thema ‘Biologische landbou

Statistical inference of the generation probability of T-cell receptors from sequence repertoires

Stochastic rearrangement of germline DNA by VDJ recombination is at the origin of immune system diversity. This process is implemented via a series of stochastic molecular events involving gene choices and random nucleotide insertions between, and deletions from, genes. We use large sequence repertoires of the variable CDR3 region of human CD4+ T-cell receptor beta chains to infer the statistical properties of these basic biochemical events. Since any given CDR3 sequence can be produced in multiple ways, the probability distribution of hidden recombination events cannot be inferred directly from the observed sequences; we therefore develop a maximum likelihood inference method to achieve this end. To separate the properties of the molecular rearrangement mechanism from the effects of selection, we focus on non-productive CDR3 sequences in T-cell DNA. We infer the joint distribution of the various generative events that occur when a new T-cell receptor gene is created. We find a rich picture of correlation (and absence thereof), providing insight into the molecular mechanisms involved. The generative event statistics are consistent between individuals, suggesting a universal biochemical process. Our distribution predicts the generation probability of any specific CDR3 sequence by the primitive recombination process, allowing us to quantify the potential diversity of the T-cell repertoire and to understand why some sequences are shared between individuals. We argue that the use of formal statistical inference methods, of the kind presented in this paper, will be essential for quantitative understanding of the generation and evolution of diversity in the adaptive immune system.Comment: 20 pages, including Appendi

Evaluation of the Dutch general exemption level for voluntary fortification with folic acid

Introduction: Fortification with folic acid was prohibited in the Netherlands. Since 2007, a general exemption is given to fortify with folic acid up until a maximum level of 100 µg/100 kcal. This maximum level was based on a calculation model and data of adults only. The model requires parameters on intake (diet, supplements, energy) and on the proportion of energy that may be fortified. This study aimed to evaluate the model parameters considering the changing fortification market. In addition, the risk of young children exceeding the UL for folic acid was studied. Methods: Folic acid fortified foods present on the Dutch market were identified in product databases and by a supermarket inventory. Together with data of the Dutch National Consumption Survey-Young Children (2005/2006) these inventory results were used to re-estimate the model parameters. Habitual folic acid intake of young children was estimated and compared to the UL for several realistic fortification scenarios. Results: Folic acid fortified foods were identified in seven different food groups. In up to 10% of the population, the proportion of energy intake of folic acid fortified foods exceeded 10% – the original model parameter. The folic acid intake from food supplements was about 100 µg/day, which is lower than the intake assumed as the original model parameter (300 µg). In the scenarios representing the current market situation, a small proportion (<5%) of the children exceeded the UL. Conclusion: The maximum fortification level of 100 µg/100 kcal is sufficiently protective for children in the current market situation. In the precautionary model to estimate the maximum fortification levels, subjects with high intakes of folic acid from food and supplements, and high energy intakes are protected from too high folic acid intakes. Combinations of high intakes are low in this population. The maximum levels should be monitored and revised with increasing fortification and supplementation practices

DNA-PKcs inhibitors sensitize neuroendocrine tumor cells to peptide receptor radionuclide therapy <i>in vitro</i> and <i>in vivo</i>

Background: Peptide receptor radionuclide therapy (PRRT) increases progression-free survival and quality of life of neuroendocrine tumor (NET) patients, however complete cures are rare and dose-limiting toxicity has been reported. PRRT induces DNA damage of which DNA double strand breaks (DSBs) are the most cytotoxic. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a key player in DSB repair and its inhibition therefore is a potential way to enhance PRRT efficacy without increasing the dosage. Methods: We analyzed effects of combining PRRT and DNA-PKcs inhibitor AZD7648 on viability, cell death and clonogenic survival on SSTR2-expressing cell lines BON1-SSTR2, GOT1 and NCI-H69. Therapy-induced DNA damage response was assessed by analyzing DSB foci levels and cell cycle distributions. In vivo efficacy was investigated in BON1-SSTR2 and NCI-H69 xenografted mice and hematologic and renal toxicity were monitored by blood counts, creatinine levels and analyzing renal morphology. Results: Combining PRRT and AZD7648 significantly decreased viability of BON1-SSTR2, GOT1 and NCI-H69 cells and induced cell death in GOT1 and BON1-SSTR2 cells. A strong effect of AZD7648 on PRRT-induced DSB repair was found. In GOT1 cells, this was accompanied by induction of cell cycle blocks. However, BON1-SSTR2 cells were unable to fully arrest their cell cycle and polyploid cells with high DNA damage levels were detected. In vivo, AZD7648 significantly sensitized BON1-SSTR2 and NCI-H69 xenograft models to PRRT. In addition, combination therapy did not induce significant changes in body weight, blood composition, plasma creatinine levels and renal morphology, indicating the absence of severe acute hematologic and renal toxicity. Conclusion: These results highlight that the potentiation of the therapeutic effect of PRRT by DNA-PKcs inhibition is a highly effective and well-Tolerated therapeutic strategy. Based on our findings, we recommend initiation of phase I/II studies in patients to find a safe and effective combination regimen.</p

Contact tracing for vancomycin-resistant Enterococcus faecium (VRE):evaluation of the Dutch policy of quintuple screening cultures

Detection of vancomycin-resistant Enterococcus faecium (VRE) is hampered by low sensitivity of rectal swab cultures. This study aimed to define the number of screening cultures needed to increase sensitivity to detect VRE transmission, and to determine time from presumed exposure to detectable colonization. In a tertiary care setting, we retrospectively analyzed data from 9 VRE outbreaks. As a proxy or estimation for time to detectable colonization, the time between first positive culture of the presumed index patient and that of their contacts was determined. Only 64% of secondary cases were positive in the first out of five cultures. By using the first three out of five rectal swabs, 89% (95%CI: 78–95%) of all secondary cases would have been identified. The median number of days between the positive culture of the index patient and the first positive culture of secondary cases was 9 days. Eleven percent of secondary cases would have been missed if only three rectal samples would have been obtained. Furthermore, our results show that one or more rectal swabs taken around day 9 after presumed exposure should at least be included in the screening approach. In our setting, obtaining a fourth and a fifth rectal swab showed a relevant additional value compared to only one to three swabs. Our findings are useful for determining the most effective VRE contact tracing approach to prevent transmission.</p

Efficacy of natural antimicrobials in toothpaste formulations against oral biofilms in vitro

AbstractObjectivesTo evaluate the antimicrobial efficacies of two toothpaste formulations containing natural antimicrobials (herbal extracts and chitosan) against oral biofilms of different composition and maturational status.MethodsBacteria from a buffer suspension or fresh saliva were adhered for 2h to a salivary conditioning film and subsequently grown for 16h. Dual-species biofilms were prepared from Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, whilst multi-species biofilms were grown from freshly collected human saliva. Biofilms were exposed to 25wt% toothpaste supernatants. A chlorhexidine-containing mouthrinse and a buffer were used as positive- and negative-controls, respectively. Antibacterial efficacy was concluded from acute killing, bacterial removal, prevention of bacterial re-deposition and continued killing during re-deposition.ResultsThe herbal- and chitosan-based supernatants showed immediate killing of oral biofilm bacteria, comparable with chlorhexidine. Moreover, exposure of a biofilm to these supernatants or chlorhexidine, yielded ongoing killing of biofilm bacteria after exposure during re-deposition of bacteria to a matured 16h biofilm, but not to a much thinner initial biofilm formed by 2h adhesion only. This suggests that thicker, more matured biofilms can absorb and release oral antimicrobials.ConclusionsSupernatants based on herbal- and chitosan-based toothpastes have comparable immediate and ongoing antibacterial efficacies as chlorhexidine. Natural antimicrobials and chlorhexidine absorb in oral biofilms which contributes to their substantive action

Microcirculatory perfusion is preserved during off-pump but not on-pump cardiac surgery

OBJECTIVE: This study investigated the perioperative course of microcirculatory perfusion in off-pump compared with on-pump surgery. Additionally, the impact of changes in systemic hemodynamics, hematocrit, and body temperature was studied. DESIGN: Prospective, nonrandomized, observational study. SETTING: Tertiary university hospital. PARTICIPANTS: Patients undergoing coronary artery bypass grafting with (n = 13) or without (n = 13) use of cardiopulmonary bypass. INTERVENTIONS: Microcirculatory measurements were obtained at 5 time points ranging from induction of anesthesia to ICU admission. MEASUREMENTS AND MAIN RESULTS: Microcirculatory recordings were performed with sublingual sidestream dark field imaging. Despite a comparable reduction in intraoperative blood pressure between groups, the perfused vessel density decreased more than 20% after onset of extracorporeal circulation but remained stable in the off-pump group. The reduction in microvascular perfusion in the on-pump group was further paralleled by decreased hematocrit and temperature. Although postbypass hematocrit levels and body temperature were restored to similar levels as in the off-pump group, the median microvascular flow index remained reduced after bypass (2.4 [2.3-2.7]) compared with baseline (2.8 [2.7-2.9]; p = 0.021). CONCLUSIONS: Microcirculatory perfusion remained unaltered throughout off-pump surgery. In contrast, microvascular perfusion declined after initiation of cardiopulmonary bypass and did not recover in the early postoperative phase

Development of a multiplexed bead-based immunoassay for the simultaneous detection of antibodies to 17 pneumococcal proteins

Presently, several pneumococcal proteins are being evaluated as potential vaccine candidates. Here, we gather novel insights in the immunogenicity of PLY, PsaA, PspA, PspC, NanA, Hyl, PpmA, SlrA, Eno, IgA1-protease, PdBD, BVH-3, SP1003, SP1633, SP1651, SP0189 and SP0376. We developed a multiplex bead-based immunoassay (xMAP® Technology, Luminex Corporation) to simultaneously quantify antibodies against these 17 pneumococcal proteins in serum. The median fluorescence intensity (MFI) values obtained for human pooled serum with the multiplex assay were between 82% and 111% (median 94%) of those obtained with the singleplex assays. For IgG, the coefficient of variation (CV) in serum ranged from 2% to 9%, for IgA, the CV ranged from 3% to 14% and for IgM, the CV ranged from 11% to 15%. Using this immunoassay, we showed that anti-pneumococcal antibody levels exhibited extensive inter-individual variability in young children suffering from invasive pneumococcal disease. All proteins, including the proteins with, as yet, unknown function, were immunogenic. In conclusion, the multiplex Streptococcus pneumoniae immunoassay based on proteins is reproducible. This assay can be used to monitor anti-S. pneumoniae antibody responses in a material- and time-saving manner

A large-scale experiment to evaluate control of invasive muskrats

The muskrat (Ondatra zibethicus) is an invasive species in Europe. The extensive waterways of the Netherlands provide ideal habitat for muskrats, and a large population established itself after arrival in 1941. A control program was put into effect immediately because muskrat burrowing can compromise the integrity of dikes and, hence, poses a significant public safety risk. The current (2015) annual catch of approximately 89,000 individuals is equivalent to approximately 0.30 muskrats/km of waterway, well above the national objective in spite of decades of effort. The control program is expensive (€35 M annually) and contested by animal rights groups. These factors created the need for a careful evaluation of the full range of control possibilities, from ‘no control’ to ‘extermination.’ As part of this, we experimentally evaluated the validity of a previously published correlation (based on historical data) between catch and effort. We raised or lowered removal effort (2013–2016) in a stratified random sample of 117 5-km × 5-km ‘atlas squares’ from the national grid. We found that catch-per-unit effort (CPUE) decreased after effort was increased, and rose after effort was decreased, by amounts slightly greater than expected based on the correlational data, though confidence intervals enclose zero. As anticipated, CPUE varied consistently and strongly between seasons. The biggest (and unanticipated) effects were those of the catch in the preceding 3 years (‘history’), and surrounding area (‘neighborhood’). Our experiment confirms estimates of intensity of control required to lower muskrat populations. These results will help with more effective allocation of control effort, and better-informed evaluation of the economic costs of various control options