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1.
An Ester of β-Hydroxybutyrate Regulates Cholesterol Biosynthesis in Rats and a Cholesterol Biomarker in Humans 下载免费PDF全文
Martin F. Kemper Shireesh Srivastava M. Todd King Kieran Clarke Richard L. Veech Robert J. Pawlosky 《Lipids》2015,50(12):1185-1193
In response to carbohydrate deprivation or prolonged fasting the ketone bodies, β‐hydroxybutyrate (βHB) and acetoacetate (AcAc), are produced from the incomplete β‐oxidation of fatty acids in the liver. Neither βHB nor AcAc are well utilized for synthesis of sterols or fatty acids in human or rat liver. To study the effects of ketones on cholesterol homeostasis a novel βHB ester (KE) ((R)‐3‐hydroxybutyl (R)‐3‐hydroxybutyrate) was synthesized and given orally to rats and humans as a partial dietary carbohydrate replacement. Rats maintained on a diet containing 30‐energy % as KE with a concomitant reduction in carbohydrate had lower plasma cholesterol and mevalonate (?40 and ?27 %, respectively) and in the liver had lower levels of the mevalonate precursors acetoacetyl‐CoA and HMG‐CoA (?33 and ?54 %) compared to controls. Whole liver and membrane LDL‐R as well as SREBP‐2 protein levels were higher (+24, +67, and +91 %, respectively). When formulated into a beverage for human consumption subjects consuming a KE drink (30‐energy %) had elevated plasma βHB which correlated with decreased mevalonate, a liver cholesterol synthesis biomarker. Partial replacement of dietary carbohydrate with KE induced ketosis and altered cholesterol homeostasis in rats. In healthy individuals an elevated plasma βHB correlated with lower plasma mevalonate. 相似文献
2.
Hannan Tahir Carles Bona-Casas Andrew James Narracott Javaid Iqbal Julian Gunn Patricia Lawford Alfons G. Hoekstra 《Journal of the Royal Society Interface》2014,11(94)
Re-establishing a functional endothelium following endovascular treatment is an important factor in arresting neointimal proliferation. In this study, both histology (in vivo) and computational simulations (in silico) are used to evaluate neointimal growth patterns within coronary arteries along the axial direction of the stent. Comparison of the growth configurations in vivo and in silico was undertaken to identify candidate mechanisms for endothelial repair. Stent, lumen and neointimal areas were measured from histological sections obtained from eight right coronary stented porcine arteries. Two re-endothelialization scenarios (endothelial cell (EC) random seeding and EC growth from proximal and distal ends) were implemented in silico to evaluate their influence on the morphology of the simulated lesions. Subject to the assumptions made in the current simulations, comparison between in vivo and in silico results suggests that endothelial growth does not occur from the proximal and distal ends alone, but is more consistent with the assumption of a random seeding process. This may occur either from the patches of endothelium which survive following stent implantation or from attachment of circulating endothelial progenitor cells. 相似文献
3.
Leonore van den Ende Alfons van Marrewijk 《International Journal of Project Management》2019,37(2):331-346
The last decades have witnessed an increasing prevalence of community resistance against large-scale infrastructure projects that pose serious threats to their environment, calling for further empirical scrutiny. Hence, this paper applies a neo-institutional lens to investigate how project actors who plan and implement large-scale infrastructure projects respond to community resistance in their attempt to legitimize and embed these projects in their environment. To do so, we draw from a longitudinal study of two subway projects in Amsterdam; the East line (1965–1980) and the North-South line (1995-2018). While considered crucial for urban development, both projects encountered severe community resistance by locals protecting the historic city. This resistance, in turn, prompted ‘institutional work’ by project actors to socially (re)construct the projects in pursuit of legitimacy from the Amsterdam community. The twofold contribution of the paper to the field of project studies is (1) the application of a neo-institutional lens showcasing the dynamic interrelation between projects and their environment, processes of institutional transformation, and practices of institutional work; and (2) the longitudinal empirical account exhibiting the contextual dialectic of resistance and accommodation with an emphasis on shifting approaches of institutionalization, the constant struggle to acquire legitimacy, and the local embeddedness of projects. 相似文献
4.
C. Corbane G. Lemoine M. Pesaresi T. Kemper F. Sabo S. Ferri 《International journal of remote sensing》2018,39(3):842-853
This article presents an experiment in which multi-temporal interferometric coherence calculated from 6-days Sentinel-1A and Sentinel-1B image pairs and backscatter intensity σ° are jointly used for the extraction of built-up areas in the framework of the symbolic machine learning classification. The results obtained with the proposed approach confirm the enhanced capabilities of discriminating built-up areas when using coherence information in comparison to two available global human settlement layers derived: (1) from Landsat optical data and (2) from Sentinel-1 ground range detected data and based on backscatter intensity σ° only. The experiment carried out in The Netherlands Randstad area is expected to be indicative of the results obtainable for urban areas having similar structures and types of built-up. 相似文献
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6.
Stephanie M. Beeman Andrew R. Kemper Michael L. Madigan Stefan M. Duma 《Accident; analysis and prevention》2013
Despite improvements in vehicle design and safety technologies, frontal automotive collisions continue to result in a substantial number of injuries and fatalities each year. Although a considerable amount of research has been performed on PMHSs and ATDs, matched dynamic whole-body frontal testing with PMHSs and the current ATD aimed at quantifying both kinetic and kinematic data in a single controlled study is lacking in the literature. Therefore, a total of 4 dynamic matched frontal sled tests were performed with three male PMHSs and a Hybrid III 50th percentile male ATD (28.6 g, Δv = 40 kph). Each subject was restrained using a 4 kN load limiting, driver-side, 3-point seatbelt. Belt force was measured for the lap belt and shoulder belt. Reaction forces were measured at the seat pan, seat back, independent foot plates, and steering column. Linear head acceleration, angular head acceleration, and pelvic acceleration were measured for all subjects. Acceleration of C7, T7, T12, both femurs, and both tibias were also measured for the PMHSs. A Vicon motion analysis system, consisting of 12 MX-T20 2 megapixel cameras, was used to quantify subject 3D motion (±1 mm) at a rate of 1 kHz. Excursions of select anatomical regions were normalized to their respective initial positions and compared by test condition and between subject types. Notable discrepancies were observed in the responses of the PMHSs and the ATD. The reaction forces and belt loading for the ATD, particularly foot plate, seat back, steering column, and lap belt forces, were not in agreement with those of the PMHSs. The forward excursions of the ATD were consistently within those of the PMHSs with the exception of the left upper extremity. This could potentially be due to the known limitations of the Hybrid III ATD shoulder and chest. The results presented herein demonstrate that there are some limitations to the current Hybrid III ATD under the loading conditions evaluated in the current study. Overall, this study presents a comprehensive data set of belt forces, reaction forces, accelerations, and bilateral displacement data that can be used to evaluate the performance of ATDs and validate computational models. 相似文献
7.
To manage the project life cycle and facilitate transitions, Project Management (PM) research often points to temporal models and structuring devices. However, the social and symbolic facet of transitions in projects remains understudied. Therefore, this research focuses on the ritualization of transitions in projects. Specifically, the aim is to gain insight into the practice and meaning of transition rituals in the project life cycle. To do so we draw from field research in the infrastructure sector where participant-observation was carried out during eight transition rituals in four Dutch construction projects, and 58 interviews were executed with project participants. The contribution to the PM debate on temporary organizing lies in the conceptualization of transition rituals as powerful symbolic and strategic practices in the project life cycle, and in the provision of an overview showcasing how, when and why transition rituals are practiced to facilitate transitions and embed a project in its environment. 相似文献
8.
9.
Pathways of sulfide oxidation by haloalkaliphilic bacteria in limited-oxygen gas lift bioreactors 总被引:1,自引:0,他引:1
Klok JB van den Bosch PL Buisman CJ Stams AJ Keesman KJ Janssen AJ 《Environmental science & technology》2012,46(14):7581-7586
Physicochemical processes, such as the Lo-cat and Amine-Claus process, are commonly used to remove hydrogen sulfide from hydrocarbon gas streams such as landfill gas, natural gas, and synthesis gas. Biodesulfurization offers environmental advantages, but still requires optimization and more insight in the reaction pathways and kinetics. We carried out experiments with gas lift bioreactors inoculated with haloalkaliphilic sulfide-oxidizing bacteria. At oxygen-limiting levels, that is, below an O(2)/H(2)S mole ratio of 1, sulfide was oxidized to elemental sulfur and sulfate. We propose that the bacteria reduce NAD(+) without direct transfer of electrons to oxygen and that this is most likely the main route for oxidizing sulfide to elemental sulfur which is subsequently oxidized to sulfate in oxygen-limited bioreactors. We call this pathway the limited oxygen route (LOR). Biomass growth under these conditions is significantly lower than at higher oxygen levels. These findings emphasize the importance of accurate process control. This work also identifies a need for studies exploring similar pathways in other sulfide oxidizers such as Thiobacillus bacteria. 相似文献
10.
This paper considers a fork-join system (or: parallel queue), which is a two-queue network in which any arrival generates jobs at both queues and the jobs synchronize before they leave the system. The focus is on methods to quantify the mean value of the ‘system’s sojourn time’ S: with S i denoting a job’s sojourn time in queue i, S is defined as max{S 1, S 2}. Earlier work has revealed that this class of models is notoriously hard to analyze. In this paper, we focus on the homogeneous case, in which the jobs generated at both queues stem from the same distribution. We first evaluate various bounds developed in the literature, and observe that under fairly broad circumstances these can be rather inaccurate. We then present a number of approximations, that are extensively tested by simulation and turn out to perform remarkably well. 相似文献