A series of amine-alkyl derivatives of 5-arylidenehydantoin 3–21 was evaluated for their ability to improve antibiotic effectiveness in two strains of Gram-negative Enterobacter aerogenes: the reference strain (ATCC-13048) and the chloramphenicol-resistant derivative over-producing the AcrAB-TolC efflux pump (CM-64). Three antibiotics, chloramphenicol, nalidixic acid and sparfloxacin were used as markers of efflux pump activity. New compounds (5–16) were obtained within 3–4 step synthesis using Knoevenagel condensation, Mitsunobu reaction and microwave aided N-alkylation. Molecular modeling based structure–activity relationship (SAR) studies were performed. The most active compounds: (Z)-5-(4-(diethylamino)benzylidene)-3-(2-hydroxy-3-(4-(2-hydroxyethyl)piperazin-1-yl)propyl)imidazolidine-2,4-dione (14) and (Z)-5-(2,4-dimethoxybenzylidene)-3-(2-hydroxy-3-(isopropylamino)propyl)imidazolidine-2,4-dione (15) induced fourfold decrease of minimal inhibition concentration (MIC) of all tested antibiotics in the strain CM-64 overexpressing the AcrAB-TolC pump. 相似文献
The publication of a large number of taxon names at all levels within the arbuscular mycorrhizal fungi (Glomeromycota) has resulted in conflicting systematic schemes and generated considerable confusion among biologists working with these important plant symbionts. A group of biologists with more than a century of collective experience in the systematics of Glomeromycota examined all available molecular–phylogenetic evidence within the framework of phylogenetic hypotheses, incorporating morphological characters when they were congruent. This study is the outcome, wherein the classification of Glomeromycota is revised by rejecting some new names on the grounds that they are founded in error and by synonymizing others that, while validly published, are not evidence-based. The proposed “consensus” will provide a framework for additional original research aimed at clarifying the evolutionary history of this important group of symbiotic fungi. 相似文献
Polyphenols contained in food have various positive effects on human health. The absorption and metabolism of polyphenols in the intestinal tract needs to be studied to estimate these effects. The Ussing chamber technique was used to investigate the transport behavior of apple polyphenols through pig small intestinal mucosa, which served as a model for human gastrointestinal mucosa. The identities and concentrations of polyphenols and their metabolites in the half-chambers (luminal and basolateral) within an incubation period of 4 h were determined by HPLC–MS/MS and HPLC–DAD (DAD = diode-array detection). Flux values were also measured. It was found that 5-caffeoylquinic acid and caffeic acid were absorbed and translocated to the basolateral side (1.9 and 3.7%, respectively), but other compounds, including glycosides of phloretin and quercetin, were observed without translocation. A Ussing chamber utilizing pig small intestinal mucosa is a suitable model for assessing the effect of apple polyphenols on mucosal integrity and nutrition absorption across porcine mucosa. 相似文献
A spontaneous deletion in the nicotinamide nucleotide transhydrogenase (Nnt) gene eliminating exons 7‐11 in C57BL/6J (B6J) mice is associated with reduced glucose‐stimulated insulin secretion in vitro, impaired glucose tolerance, higher epigonadal fat mass, and altered susceptibility to diet induced obesity of male B6J mice was proposed. A potential implication for NNT in human adipose tissue distribution has not been investigated so far.
Design and Methods:
Therefore, NNT mRNA expression in paired human samples of visceral (vis) and subcutaneous (sc) adipose tissue from 221 subjects with a wide range of body mass index (BMI), insulin sensitivity, and glucose tolerance was analyzed.
Results:
NNT mRNA expression is significantly higher in visceral fat of obese patients and correlates with body weight, BMI, % body fat, visceral and sc fat area, waist and hip circumference, and fasting plasma insulin (FPI). Multivariate linear regression analysis revealed visceral NNT expression as age and gender independent predictor of BMI, waist circumference, visceral fat area, and % body fat, but not FPI and 2 h OGTT glucose.
Conclusion:
In conclusion, a functional relevance of NNT in the development of human obesity and visceral fat distribution was suggested here. 相似文献
We assessed soil fungal diversity and community structure at two sampling times (t1 = 47 days and t2 = 104 days of plant age) in pots associated with four maize cultivars, including two genetically modified (GM) cultivars by high-throughput pyrosequencing of the 18S rRNA gene using DNA and RNA templates. We detected no significant differences in soil fungal diversity and community structure associated with different plant cultivars. However, DNA-based analyses yielded lower fungal OTU richness as compared to RNA-based analyses. Clear differences in fungal community structure were also observed in relation to sampling time and the nucleic acid pool targeted (DNA versus RNA). The most abundant soil fungi, as recovered by DNA-based methods, did not necessary represent the most “active” fungi (as recovered via RNA). Interestingly, RNA-derived community compositions at t1 were highly similar to DNA-derived communities at t2, based on presence/absence measures of OTUs. We recovered large proportions of fungal sequences belonging to arbuscular mycorrhizal fungi and Basidiomycota, especially at the RNA level, suggesting that these important and potentially beneficial fungi are not affected by the plant cultivars nor by GM traits (Bt toxin production). Our results suggest that even though DNA- and RNA-derived soil fungal communities can be very different at a given time, RNA composition may have a predictive power of fungal community development through time. 相似文献
The secondary structure change of the Abeta peptide to beta‐sheet was proposed as an early event in Alzheimer's disease. The transition may be used for diagnostics of this disease in an early state. We present an Attenuated Total Reflection (ATR) sensor modified with a specific antibody to extract minute amounts of Abeta peptide out of a complex fluid. Thereby, the Abeta peptide secondary structure was determined in its physiological aqueous environment by FTIR‐difference‐spectroscopy. The presented results open the door for label‐free Alzheimer diagnostics in cerebrospinal fluid or blood. It can be extended to further neurodegenerative diseases.
An immunologic ATR‐FTIR sensor for Abeta peptide secondary structure analysis in complex fluids is presented. 相似文献
Postoperative junctional ectopic tachycardia (JET) occurs frequently after pediatric cardiac surgery. R-wave synchronized atrial (AVT) pacing is used to re-establish atrioventricular synchrony. AVT pacing is complex, with technical pitfalls. We sought to establish and to test a low-cost simulation model suitable for training and analysis in AVT pacing.
Methods
A simulation model was developed based on a JET simulator, a simulation doll, a cardiac monitor, and a pacemaker. A computer program simulated electrocardiograms. Ten experienced pediatric cardiologists tested the model. Their performance was analyzed using a testing protocol with 10 working steps.
Results
Four testers found the simulation model realistic; 6 found it very realistic. Nine claimed that the trial had improved their skills. All testers considered the model useful in teaching AVT pacing. The simulation test identified 5 working steps in which major mistakes in performance test may impede safe and effective AVT pacing and thus permitted specific training. The components of the model (exclusive monitor and pacemaker) cost less than $50. Assembly and training-session expenses were trivial.
Conclusions
A realistic, low-cost simulation model of AVT pacing is described. The model is suitable for teaching and analyzing AVT pacing technique. 相似文献
We propose Turing Learning, a novel system identification method for inferring the behavior of natural or artificial systems. Turing Learning simultaneously optimizes two populations of computer programs, one representing models of the behavior of the system under investigation, and the other representing classifiers. By observing the behavior of the system as well as the behaviors produced by the models, two sets of data samples are obtained. The classifiers are rewarded for discriminating between these two sets, that is, for correctly categorizing data samples as either genuine or counterfeit. Conversely, the models are rewarded for ‘tricking’ the classifiers into categorizing their data samples as genuine. Unlike other methods for system identification, Turing Learning does not require predefined metrics to quantify the difference between the system and its models. We present two case studies with swarms of simulated robots and prove that the underlying behaviors cannot be inferred by a metric-based system identification method. By contrast, Turing Learning infers the behaviors with high accuracy. It also produces a useful by-product—the classifiers—that can be used to detect abnormal behavior in the swarm. Moreover, we show that Turing Learning also successfully infers the behavior of physical robot swarms. The results show that collective behaviors can be directly inferred from motion trajectories of individuals in the swarm, which may have significant implications for the study of animal collectives. Furthermore, Turing Learning could prove useful whenever a behavior is not easily characterizable using metrics, making it suitable for a wide range of applications. 相似文献
150 years “Biogenetic Law” The zoologist Ernst Haeckel is one of the most well‐known, but also one of the most controversial scientists of the late 19th and early 20th centuries. He was one of the earliest Darwinists and a forceful advocate of evolutionary theory. Together with “Darwin's Bulldog” Thomas Henry Huxley, Haeckel was a central figure in the early history and popularization of Darwinism. But his name is not only a symbol for the disputes about the theory of evolution and its popularization, but also for a campaign for monism, a world‐view or philosophy created by Haeckel himself. Together with Fritz Müller, Ernst Haeckel was one of the first to formulate a “Biogenetic Law”. He also created several concepts and terms still in use in biology today, such as “ontogeny”, “phylogeny”, “ecology”, “cholorogy” and “phylum” in his first, and maybe most important book “General Morphology of Organism”, which was published in 1866, 150 years ago. 相似文献
An efficient DNA extraction protocol and polymerase chain reaction (PCR) assay for detecting Leptosphaeria maculans from infected seed lots of oilseed rape were developed. L. maculans, the causal agent of blackleg, a damaging disease in oilseeds rape/canola worldwide, was listed as a quarantine disease by China in 2009. China imports several millions of tons of oilseeds every year. So there is a high risk that this pathogen will be introduced to China via contaminated seeds. Seed contamination is one of the most significant factors in the global spread of phytopathogens. Detection of L. maculans in infected seed lots by PCR assay is difficult due to the low level of pathogen mycelium/spores on seeds and PCR inhibitors associated with the seeds of oilseed rape. In our study, these two major obstacles were overcome by the development of a two‐step extraction protocol combined with a nested PCR. This extraction protocol (kit extraction after CTAB method) can efficiently extract high‐quality DNA for PCR. Amplification results showed that the detection threshold for conventional PCR and nested PCR was, respectively, 1 ng and 10 fg of DNA per μl in mycelia samples. On contaminated seed lots of oilseed rape, the detection threshold of conventional and nested PCR was 709 fg/μl and 709 ag/μl of DNA, respectively. The DNA extraction protocol and PCR assay developed in this study can be used for rapid and reliable detection of L. maculans from infected seeds of oilseed rape . 相似文献