176 research outputs found

    Eiwitsynthese in een celvrij leversysteem

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    Chromosomal targeting of replicating plasmids in the yeast Hansenula polymorpha

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    Using an optimized transformation protocol we have studied the possible interactions between transforming plasmid DNA and the Hansenula polymorpha genome. Plasmids consisting only of a pBR322 replicon, an antibiotic resistance marker for Escherichia coli and the Saccharomyces cerevisiae LEU2 gene were shown to replicate autonomously in the yeast at an approximate copy number of 6 (copies per genome equivalent). This autonomous behaviour is probably due to an H. polymorpha replicon-like sequence present on the S. cerevisiae LEU2 gene fragment. Plasmids replicated as multimers consisting of monomers connected in a head-to-tail configuration. Two out of nine transformants analysed appeared to contain plasmid multimers in which one of the monomers contained a deletion. Plasmids containing internal or flanking regions of the genomic alcohol oxidase gene were shown to integrate by homologous single or double cross-over recombination. Both single- and multi-copy (two or three) tandem integrations were observed. Targeted integration occurred in 1-22 % of the cases and was only observed with plasmids linearized within the genomic sequences, indicating that homologous linear ends are recombinogenic in H. polymorpha. In the cases in which no targeted integration occurred, double-strand breaks were efficiently repaired in a homology-independent way. Repair of double-strand breaks was precise in 50-68% of the cases. Linearization within homologous as well as nonhomologous plasmid regions stimulated transformation frequencies up to 15-fold

    Estrogen-inducible and liver-specific expression of the chicken very low density apolipoprotein II gene locus in transgenic mice.

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    We have examined the chicken Very Low Density Apolipoprotein II (apoVLDL II) gene locus in transgenic mice. A DNA fragment composed of the transcribed region, 16 kb of 5' flanking and 400 bp of 3' flanking sequences contained all the information sufficient for estrogen-inducible, liver-specific expression of the apoVLDL II gene. The far-upstream region contains a Negative Regulating Element coinciding with a DNaseI-hypersensitive site at -11 kb. In transgenic mice, the NRE at -11 kb is used for downregulating the expression to a lower maximum level. The NRE might be used for modulating apoVLDL II gene expression, and may be involved in the rapid shut-down of the expression after hormone removal

    Evaluation of the theory-based Quality Improvement in Physical Therapy (QUIP) programme: a one-group, pre-test post-test pilot study

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    BACKGROUND: Guideline adherence in physical therapy is far from optimal, which has consequences for the effectiveness and efficiency of physical therapy care. Programmes to enhance guideline adherence have, so far, been relatively ineffective. We systematically developed a theory-based Quality Improvement in Physical Therapy (QUIP) programme aimed at the individual performance level (practicing physiotherapists; PTs) and the practice organization level (practice quality manager; PQM). The aim of the study was to pilot test the multilevel QUIP programme’s effectiveness and the fidelity, acceptability and feasibility of its implementation. METHODS: A one-group, pre-test, post-test pilot study (N = 8 practices; N = 32 PTs, 8 of whom were also PQMs) done between September and December 2009. Guideline adherence was measured using clinical vignettes that addressed 12 quality indicators reflecting the guidelines’ main recommendations. Determinants of adherence were measured using quantitative methods (questionnaires). Delivery of the programme and management changes were assessed using qualitative methods (observations, group interviews, and document analyses). Changes in adherence and determinants were tested in the paired samples T-tests and expressed in effect sizes (Cohen’s d). RESULTS: Overall adherence did not change (3.1%; p = .138). Adherence to three quality indicators improved (8%, 24%, 43%; .000 ≤ p ≤ .023). Adherence to one quality indicator decreased (−15.7%; p = .004). Scores on various determinants of individual performance improved and favourable changes at practice organizational level were observed. Improvements were associated with the programme’s multilevel approach, collective goal setting, and the application of self-regulation; unfavourable findings with programme deficits. The one-group pre-test post-test design limits the internal validity of the study, the self-selected sample its external validity. CONCLUSIONS: The QUIP programme has the potential to change physical therapy practice but needs considerable revision to induce the ongoing quality improvement process that is required to optimize overall guideline adherence. To assess its value, the programme needs to be tested in a randomized controlled trial

    Pyrethrins Protect Pyrethrum Leaves Against Attack by Western Flower Thrips, Frankliniella occidentalis

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    Pyrethrins are active ingredients extracted from pyrethrum flowers (Tanacetum cinerariifolium), and are the most widely used botanical insecticide. However, several thrips species are commonly found on pyrethrum flowers in the field, and are the dominant insects found inside the flowers. Up to 80 % of western flower thrips (WFT, Frankliniella occidentalis) adults died within 3 days of initiating feeding on leaves of pyrethrum, leading us to evaluate the role of pyrethrins in the defense of pyrethrum leaves against WFT. The effects of pyrethrins on WFT survival, feeding behavior, and reproduction were measured both in vitro and in planta (infiltrated leaves). The lethal concentration value (LC50) for pyrethrins against WFT adults was 12.9 mg/ml, and pyrethrins at 0.1 % (w/v) and 1 % (w/v) had significantly negative effects on feeding, embryo development, and oviposition. About 20-70 % of WFT were killed within 2 days when they were fed chrysanthemum leaves containing 0.01-1 % pyrethrins. Chrysanthemum leaves containing 0.1 % or 1 % pyrethrins were significantly deterrent to WFT. In a no-choice assay, the reproduction of WFT was reduced significantly when the insects were fed leaves containing 0.1 % pyrethrins, and no eggs were found in leaves containing 1 % pyrethrins. Our results suggest that the natural concentrations of pyrethrins in the leaves may be responsible for the observed high mortality of WFT on pyrethrum

    Antibiotic susceptibility of Atopobium vaginae

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    BACKGROUND: Previous studies have indicated that a recently described anaerobic bacterium, Atopobium vaginae is associated with bacterial vaginosis (BV). Thus far the four isolates of this fastidious micro-organism were found to be highly resistant to metronidazole and susceptible for clindamycin, two antibiotics preferred for the treatment of BV. METHODS: Nine strains of Atopobium vaginae, four strains of Gardnerella vaginalis, two strains of Lactobacillus iners and one strain each of Bifidobacterium breve, B. longum, L. crispatus, L. gasseri and L. jensenii were tested against 15 antimicrobial agents using the Etest. RESULTS: All nine strains of A. vaginae were highly resistant to nalidixic acid and colistin while being inhibited by low concentrations of clindamycin (range: < 0.016 μg/ml), rifampicin (< 0.002 μg/ml), azithromycin (< 0.016 – 0.32 μg/ml), penicillin (0.008 – 0.25 μg/ml), ampicillin (< 0.016 – 0.94 μg/ml), ciprofloxacin (0.023 – 0.25 μg/ml) and linezolid (0.016 – 0.125 μg/ml). We found a variable susceptibility for metronidazole, ranging from 2 to more than 256 μg/ml. The four G. vaginalis strains were also susceptible for clindamycin (< 0.016 – 0.047 μg/ml) and three strains were susceptible to less than 1 μg/ml of metronidazole. All lactobacilli were resistant to metronidazole (> 256 μg/ml) but susceptible to clindamycin (0.023 – 0.125 μg/ml). CONCLUSION: Clindamycin has higher activity against G. vaginalis and A. vaginae than metronidazole, but not all A. vaginae isolates are metronidazole resistant, as seemed to be a straightforward conclusion from previous studies on a more limited number of strains

    Evaluation of the HadGEM3-A simulations in view of detection and attribution of human influence on extreme events in Europe

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    A detailed analysis is carried out to assess the HadGEM3-A global atmospheric model skill in simulating extreme temperatures, precipitation and storm surges in Europe in the view of their attribution to human influence. The analysis is performed based on an ensemble of 15 atmospheric simulations forced with observed Sea Surface Temperature of the 54 year period 1960-2013. These simulations, together with dual simulations without human influence in the forcing, are intended to be used in weather and climate event attribution. The analysis investigates the main processes leading to extreme events, including atmospheric circulation patterns, their links with temperature extremes, land-atmosphere and troposphere-stratosphere interactions. It also compares observed and simulated variability, trends and generalized extreme value theory parameters for temperature and precipitation. One of the most striking findings is the ability of the model to capture North Atlantic atmospheric weather regimes as obtained from a cluster analysis of sea level pressure fields. The model also reproduces the main observed weather patterns responsible for temperature and precipitation extreme events. However, biases are found in many physical processes. Slightly excessive drying may be the cause of an overestimated summer interannual variability and too intense heat waves, especially in central/northern Europe. However, this does not seem to hinder proper simulation of summer temperature trends. Cold extremes appear well simulated, as well as the underlying blocking frequency and stratosphere-troposphere interactions. Extreme precipitation amounts are overestimated and too variable. The atmospheric conditions leading to storm surges were also examined in the Baltics region. There, simulated weather conditions appear not to be leading to strong enough storm surges, but winds were found in very good agreement with reanalyses. The performance in reproducing atmospheric weather patterns indicates that biases mainly originate from local and regional physical processes. This makes local bias adjustment meaningful for climate change attribution

    Key signalling nodes in mammary gland development and cancer. The Snail1-Twist1 conspiracy in malignant breast cancer progression

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    Breast cancer is the most common cancer among women, and despite significant advances in diagnosing and treating it, metastatic spread of cancer cells results in a high mortality rate. Epithelial-to-mesenchymal transition (EMT) is an embryonic program in which epithelial cells lose their characteristics and gain mesenchymal features. Therefore, EMT might play a very important role during malignant tumour progression. In this review we summarise recent advances in breast cancer research with a particular focus on the transcription factors Snail1 and Twist1. Besides discussing the role of EMT in normal mammary gland development, we describe regulatory mechanisms involving newly discovered upstream regulators and microRNAs, the association of EMT with breast cancer stem cells, and the involvement of the tumour microenvironment in breast cancer progression
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