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1.
Fayazpour F Lucas B Alvarez-Lorenzo C Sanders NN Demeester J De Smedt SC 《Biomacromolecules》2006,7(10):2856-2862
In this study the physicochemical and transfection properties of cationic hydroxyethylcellulose/plasmid DNA (pDNA) nanoparticles were investigated and compared with the properties of DNA nanoparticles based on polyethylene imine (PEI), which is widely investigated as a gene carrier. The two types of cationic hydroxyethylcelluloses studied, polyquaternium-4 (PQ-4) and polyquaternium-10 (PQ-10), are already commonly used in cosmetic and topical drug delivery devices. Both PQ-4 and PQ-10 spontaneously interact with pDNA with the formation of nanoparticles approximately 200 nm in size. Gel electrophoresis and fluorescence dequenching experiments indicated that the interactions between pDNA and the cationic celluloses were stronger than those between pDNA and PEI. The cationic cellulose/pDNA nanoparticles transfected cells to a much lesser extent than the PEI-based pDNA nanoparticles. The low transfection property of the PQ-4/pDNA nanoparticles was attributed to their neutrally charged surface, which does not allow an optimal binding of PQ-4/pDNA nanoparticles to cellular membranes. Although the PQ-10/pDNA nanoparticles were positively charged and thus expected to be taken up by cells, they were also much less efficient in transfecting cells than were PEI/pDNA nanoparticles. Agents known to enhance the endosomal escape were not able to improve the transfection properties of PQ-10/pDNA nanoparticles, indicating that a poor endosomal escape is, most likely, not the major reason for the low transfection activity of PQ-10/pDNA nanoparticles. We hypothesized that the strong binding of pDNA to PQ-10 prohibits the release of pDNA from PQ-10 once the PQ-10/pDNA nanoparticles arrive in the cytosol of the cells. Tailoring the nature and extent of the cationic side chains on this type of cationic hydroxyethylcellulose may be promising to further enhance their DNA delivery properties. 相似文献
2.
Feyisara Eyiwumi Oni Niels Geudens Joseph T. Onyeka Oluwatoyin Faith Olorunleke Ayodeji Ekundayo Salami Olumide Owolabi Omoboye Anthony Arguelles Arias Amayana Adiobo Stefaan De Neve Marc Ongena José C. Martins Monica Höfte 《Environmental microbiology》2020,22(12):5137-5155
Pseudomonas isolates from tropical environments have been underexplored and may form an untapped reservoir of interesting secondary metabolites. In this study, we compared Pseudomonas and cyclic lipopeptide (CLP) diversity in the rhizosphere of a cocoyam root rot disease (CRRD) suppressive soil in Boteva, Cameroon with those from four conducive soils in Cameroon and Nigeria. Compared with other soils, Boteva andosols were characterized by high silt, organic matter, nitrogen and calcium. Besides, the cocoyam rhizosphere at Boteva was characterized by strains belonging mainly to the P. koreensis and P. putida (sub)groups, with representations in the P. fluorescens, P. chlororaphis, P. jessenii and P. asplenii (sub)groups. In contrast, P. putida isolates were prominent in conducive soils. Regarding CLP diversity, Boteva was characterized by strains producing 11 different CLP types with cocoyamide A producers, belonging to the P. koreensis group, being the most abundant. However, putisolvin III-V producers were the most dominant in the rhizosphere of conducive soils in both Cameroon and Nigeria. Furthermore, we elucidated the chemical structure of putisolvin derivatives—putisolvin III-V, and described its biosynthetic gene cluster. We show that high Pseudomonas and metabolic diversity may be driven by microbial competition, which likely contributes to soil suppressiveness to CRRD. 相似文献
3.
Timm Intemann Kirsten Mehlig Stefaan De Henauw Alfonso Siani Tassos Constantinou Luis A. Moreno Dénes Molnár Toomas Veidebaum Iris Pigeot 《Biometrical journal. Biometrische Zeitschrift》2020,62(1):221-237
Modelling dietary data, and especially 24-hr dietary recall (24HDR) data, is a challenge. Ignoring the inherent measurement error (ME) leads to biased effect estimates when the association between an exposure and an outcome is investigated. We propose an adapted simulation extrapolation (SIMEX) algorithm for modelling dietary exposures. For this purpose, we exploit the ME model of the NCI method where we assume the assumption of normally distributed errors of the reported intake on the Box-Cox transformed scale and of unbiased recalls on the original scale. According to the SIMEX algorithm, remeasurements of the observed data with additional ME are generated in order to estimate the association between the level of ME and the resulting effect estimate. Subsequently, this association is extrapolated to the case of zero ME to obtain the corrected estimate. We show that the proposed method fulfils the key property of the SIMEX approach, that is, that the MSE of the generated data will converge to zero if the ME variance converges to zero. Furthermore, the method is applied to real 24HDR data of the I.Family study to correct the effects of salt and alcohol intake on blood pressure. In a simulation study, the method is compared with the NCI method resulting in effect estimates with either smaller MSE or smaller bias in certain situations. In addition, we found our method to be more informative and easier to implement. Therefore, we conclude that the proposed method is useful to promote the dissemination of ME correction methods in nutritional epidemiology. 相似文献
4.
Maike Wolters Valeria Pala Paola Russo Patrizia Risé Luis A. Moreno Stefaan De Henauw Kirsten Mehlig Toomas Veidebaum Denés Molnár Michael Tornaritis Claudio Galli Wolfgang Ahrens Claudia B?rnhorst 《PloS one》2016,11(11)
BackgroundPolyunsaturated n-3 and n-6 polyunsaturated fatty acids (PUFA) are precursors of biologically active metabolites that affect blood pressure (BP) regulation. This study investigated the association of n-3 and n-6 PUFA and BP in children and adolescents.MethodsIn a subsample of 1267 children aged 2–9 years at baseline of the European IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) cohort whole blood fatty acids were measured by a validated gas chromatographic method. Systolic and diastolic BP was measured at baseline and after two and six years. Mixed-effects models were used to assess the associations between fatty acids at baseline and BP z-scores over time adjusting for relevant covariables. Models were further estimated stratified by sex and weight status.ResultsThe baseline level of arachidonic acid was positively associated with subsequent systolic BP (β = 0.08, P = 0.002) and diastolic BP (β = 0.07, P<0.001). In thin/normal weight children, baseline alpha-linolenic (β = -1.13, P = 0.003) and eicosapentaenoic acid (β = -0.85, P = 0.003) levels were inversely related to baseline and also to subsequent systolic BP and alpha-linolenic acid to subsequent diastolic BP. In overweight/obese children, baseline eicosapentaenoic acid level was positively associated with baseline diastolic BP (β = 0.54, P = 0.005).ConclusionsLow blood arachidonic acid levels in the whole sample and high n-3 PUFA levels in thin/normal weight children are associated with lower and therefore healthier BP. The beneficial effects of high n-3 PUFA on BP were not observed in overweight/obese children, suggesting that they may have been overlaid by the unfavorable effects of excess weight. 相似文献
5.
This study aimed to measure changes in socioeconomic inequalities in smoking and smoking cessation due to the 2006 smoking ban in Luxembourg. Data were derived from the PSELL3/EU-SILC (Panel Socio-Economique Liewen Zu Letzebuerg/European Union—Statistic on Income and Living Conditions) survey, which was a representative survey of the general population aged ≥16 years conducted in Luxembourg in 2005, 2007, and 2008. Smoking prevalence and smoking cessation due to the 2006 smoking ban were used as the main smoking outcomes. Two inequality measures were calculated to assess the magnitude and temporal trends of socioeconomic inequalities in smoking: the prevalence ratio and the disparity index. Smoking cessation due to the smoking ban was considered as a positive outcome. Three multiple logistic regression models were used to assess social inequalities in smoking cessation due to the 2006 smoking ban. Education level, income, and employment status served as proxies for socioeconomic status. The prevalence of smoking decreased by 22.5% between 2005 and 2008 (from 23.1% in 2005 to 17.9% in 2008), but socioeconomic inequalities in smoking persisted. Smoking prevalence decreased by 24.2% and 20.2% in men and women, respectively; this difference was not statistically significant. Smoking cessation in daily smokers due to the 2006 smoking ban was associated with education level, employment status, and income, with higher percentages of quitters among those with a lower socioeconomic status. The decrease in smoking prevalence after the 2006 law was also associated with a reduction in socioeconomic inequalities, including differences in education level, income, and employment status. Although the smoking ban contributed to a reduction of such inequalities, they still persist, indicating the need for a more targeted approach of smoke-free policies directed toward lower socioeconomic groups. 相似文献
6.
Cultural attraction theory (CAT) describes a general evolutionary process, cultural attraction, by which the spread and stability of cultural items (beliefs, practices, artifacts, etc.) result not just from differential reproduction, but also from transformations that systematically favor the reconstruction of cultural items of specific types. In this way, CAT aims to provide a general framework for the study of cultural evolution. In a thoughtful critical analysis, Buskell questions the ability of CAT to provide methodological guidance for research in cultural evolution. Can CAT be used to develop the sort of mid‐range theories and models that often drive empirical work? Here we argue that CAT can indeed be used in this way, and we outline the methodological practices that students of cultural attraction have used and are currently developing. 相似文献
7.
Sahouli Salima Abdeddaim Katia K. Werbrouck Stefaan P. O. 《In vitro cellular & developmental biology. Plant》2022,58(4):664-670
In Vitro Cellular & Developmental Biology - Plant - Oleasters are olive genotypes that range from wild to feral. They are tolerant to biotic and abiotic stresses and are easily propagated. This... 相似文献
8.
Van Onckelen Henri A.; Horemans Stefaan; De Greef Jan A. 《Plant & cell physiology》1981,22(3):507-515
During the early stages of germination and vegetative development,cotyledons of intact bean (Phaseolus vulgaris L.) seedlingsshowed active ABA catabolism causing a low endogenous ABA content.At the end of the substrate mobilizing phase, when the cotyledonsbecame senescent, a drastic increase of the endogenous ABA contentlinked with a decrease of the ABA catabolic activity was observed.This indicates that a close connection exists between senescenceand endogenous ABA content and metabolism in bean cotyledons. Removal of the apical growth region induced in the cotyledonsactivation of the ABA catabolism and the endogenous ABA concentrationdecreased below the detection limit (0.1 ng/g fr wt) at theonset of the outgrowth of the axillary buds. From then, apicaldominance was restored and the cotyledons returned to the senescentstate, which was correlated with a drastic increase of theirendogenous ABA content.
1 Bevoegd verklaard navorser N. F. W. O.
2 Wetenschappelijk medewerker F. K. F. O. (Received November 25, 1980; Accepted February 13, 1981) 相似文献
9.
Stefaan De Wildeman Gabriele Diekert Herman Van Langenhove Willy Verstraete 《Applied microbiology》2003,69(9):5643-5647
The suspected carcinogen 1,2-dichloroethane (1,2-DCA) is the most abundant chlorinated C2 groundwater pollutant on earth. However, a reductive in situ detoxification technology for this compound does not exist. Although anaerobic dehalorespiring bacteria are known to catalyze several dechlorination steps in the reductive-degradation pathway of chlorinated ethenes and ethanes, no appropriate isolates that selectively and metabolically convert them into completely dechlorinated end products in defined growth media have been reported. Here we report on the isolation of Desulfitobacterium dichloroeliminans strain DCA1, a nutritionally defined anaerobic dehalorespiring bacterium that selectively converts 1,2-dichloroethane and all possible vicinal dichloropropanes and -butanes into completely dechlorinated end products. Menaquinone was identified as an essential cofactor for growth of strain DCA1 in pure culture. Strain DCA1 converts chiral chlorosubstrates, revealing the presence of a stereoselective dehalogenase that exclusively catalyzes an energy-conserving anti mechanistic dichloroelimination. Unlike any known dehalorespiring isolate, strain DCA1 does not carry out reductive hydrogenolysis reactions but rather exclusively dichloroeliminates its substrates. This unique dehalorespiratory biochemistry has shown promising application possibilities for bioremediation purposes and fine-chemical synthesis. 相似文献
10.
Lithium Fluoride Based Electron Contacts for High Efficiency n‐Type Crystalline Silicon Solar Cells 下载免费PDF全文
James Bullock Peiting Zheng Quentin Jeangros Mahmut Tosun Mark Hettick Carolin M. Sutter‐Fella Yimao Wan Thomas Allen Di Yan Daniel Macdonald Stefaan De Wolf Aïcha Hessler‐Wyser Andres Cuevas Ali Javey 《Liver Transplantation》2016,6(14)
Low‐resistance contact to lightly doped n‐type crystalline silicon (c‐Si) has long been recognized as technologically challenging due to the pervasive Fermi‐level pinning effect. This has hindered the development of certain devices such as n‐type c‐Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c‐Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm2 scale contact resistivities on lightly doped n‐type c‐Si via a lithium fluoride/aluminum contact. The realization of this low‐resistance contact enables the fabrication of a first‐of‐its‐kind high‐efficiency n‐type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof‐of‐concept stage. The implementation of the LiFx/Al contact mitigates the need for the costly high‐temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p‐type to n‐type c‐Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c‐Si photovoltaic industry. 相似文献