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排序方式: 共有65条查询结果,搜索用时 15 毫秒
51.
Sofija E. Zagarins Alayne G. Ronnenberg Stephen H. Gehlbach Rongheng Lin Elizabeth R. Bertone-Johnson 《Journal of clinical densitometry》2010,13(4):392-398
Total body mass is a major determinant of bone mass, but studies of the relative contributions of lean mass (LM) and fat mass (FM) to bone mass have yielded conflicting results. This is likely because of the use of bone measures that are not adequately adjusted for body size and, therefore, not appropriate for analyses related to body composition, which is also correlated with body size. We examined the relationship between body composition and peak bone mass in premenopausal women aged 18–30 yr using both size-dependent and size-adjusted measures of bone density and body composition, as well as statistical models adjusted for size-related factors. We measured total bone mass and areal bone density using dual-energy X-ray absorptiometry, and used established formulas to calculate estimates of volumetric (size-adjusted) bone density. LM tended to be positively associated with bone both before and after adjustment for size-related factors. FM and body fat percentage, however, were positively associated with size-dependent bone measures, but adjusting for size removed or reversed this association. These findings suggest that the association between bone mass and body composition, especially FM, is dependent on the bone measures analyzed, and that determining the most appropriate size-adjustment techniques is critical for understanding this relationship. 相似文献
52.
Jane Garb Garry Welch Sofija Zagarins Jay Kuhn John Romanelli 《Obesity surgery》2009,19(10):1447-1455
Bariatric surgery has emerged as an important tool in the fight against morbid obesity. However, reviewers have noted that there is a scarcity of long-term clinical surveillance data for bariatric surgery beyond 1-year follow-up and that a high percentage of patients are lost to follow-up, raising questions regarding the accuracy of current outcomes estimates. A meta-analysis of clinical reports providing bariatric surgery weight loss outcomes for morbidly obese patients was conducted over the period 2003–2007. Studies included were randomized controlled trials, nonrandomized controlled trials, and consecutive case series involving patients receiving either laparoscopic adjustable gastric banding (LAGB) or laparoscopic gastric bypass (LGB) surgery. Included studies involved n = 7,383 patients and were largely academic hospital-based (78.6%) and retrospective in design (71.4%). Weight loss outcome was defined by percent excess weight loss (%EWL). Composite estimates showed a significantly greater %EWL for LGB surgery (62.6%) compared to LAGB (49.4%). The superiority of LGB persisted at all three postsurgical time points examined (1, 2, and >3 years). Problems were identified regarding incomplete or suboptimal data reporting in many studies reviewed, and high patient attrition was evident at 2-year (49.8% LAGB, 75.2% LGB) and >3-year (82.6% LAGB, 89% LGB) end points. This meta-analysis confirms the superiority of LGB to LAGB in %EWL found in earlier studies. Although problems in study quality raised significant concerns regarding the validity of current weight loss estimates in this area, there was no evidence of publication bias. 相似文献
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Calcium dynamics in leech neurons were studied using a fast CCD camera. Fluorescence changes (DeltaF/F) of the membrane impermeable calcium indicator Oregon Green were measured. The dye was pressure injected into the soma of neurons under investigation. DeltaF/F caused by a single action potential (AP) in mechanosensory neurons had approximately the same amplitude and time course in the soma and in distal processes. By contrast, in other neurons such as the Anterior Pagoda neuron, the Annulus Erector motoneuron, the L motoneuron, and other motoneurons, APs evoked by passing depolarizing current in the soma produced much larger fluorescence changes in distal processes than in the soma. When APs were evoked by stimulating one distal axon through the root, DeltaF/F was large in all distal processes but very small in the soma. Our results show a clear compartmentalization of calcium dynamics in most leech neurons in which the soma does not give propagating action potentials. In such cells, the soma, while not excitable, can affect information processing by modulating the sites of origin and conduction of AP propagation in distal excitable processes. 相似文献
54.
Prominence of concrete is characterized by its high mechanical properties and durability, combined with multifunctionality and aesthetic appeal. Development of alternative eco-friendly or multipurpose materials has conditioned improvements in concrete mix design to optimize concrete production speed and price, as well as carbon footprint. Artificial neural networks represent a new and efficient tool in achieving optimal concrete mixtures according to its intended function. This paper addresses concrete mix design and the application of artificial neural networks (ANNs) for self-sensing concrete. The authors review concrete mix design methods and the development of ANNs for prediction of properties for various types of concrete. Furthermore, the authors present developments and applications of ANNs for prediction of compressive strength and flexural strength of carbon nanotubes/carbon nanofibers (CNT/CNF) reinforced concrete using experimental results for the learning process. The goal is to bring the ANN approach closer to a variety of concrete researchers and possibly propose the implementation of ANNs in the civil engineering practice. 相似文献
55.
Dordević S Petrović S Dobrić S Milenković M Vucićević D Zizić S Kukić J 《Journal of ethnopharmacology》2007,110(3):458-463
In the Moroccan traditional medicine, the ripe fruits of Carum carvi L. (Apiaceae) and the leaves of Tanacetum vulgare L. (Asteraceae/Compositae), two widely available plant materials, are used as diuretics. Since, the diuretic activity of these substances has not been investigated in scientifically controlled studies, the aim of the present study was to evaluate the diuretic potential of aqueous extracts of Carum carvi fruit (caraway) and the leaves of Tanacetum vulgare (tansy) in normal rats after acute and sub-chronic oral administration. Water extracts of Carum carvi and Tanacetum vulgare (100 mg/kg) or the reference drug, furosemide (10 mg/kg) were administrated orally to male Wistar rats and their urine output was quantitated at several intervals of time after the dose. After single doses of the extracts of both caraway seeds and tansy leaves, urine output was significantly increased at all time points, and at 24 h after the dose, the total volume of urine excreted was similar for the plant extracts and furosemide. Both extracts increased urinary levels of Na+ and K+, to about the same extent, while furosemide increased urinary levels of only Na+ and decreased urinary K+. Despite changes in urinary excretion of the electrolytes, plasma Na+ and K+ levels were not affected by any of the three substances. In the 8-day sub-chronic study, all three substances induced significant diuresis and natriuresis; only tansy increased urinary potassium excretion. The plant extracts did not appear to have renal toxicity or any other adverse effects during the study period. In conclusion, water extracts of both Carum carvi and Tanacetum vulgare have strong diuretic action confirming their ethnopharmacological use. From the pattern of excretion of water, sodium and potassium, it may be deduced that there are atleast two types of active principals present in these extracts, one having a furosemide-like activity and the other a thiazide-like activity. 相似文献
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Kai J. Neelsen Isabella M.Y. Zanini Sofija Mijic Raquel Herrador Ralph Zellweger Arnab Ray Chaudhuri Kevin D. Creavin J. Julian Blow Massimo Lopes 《Genes & development》2013,27(23):2537-2542
Deregulated origin licensing and rereplication promote genome instability and tumorigenesis by largely elusive mechanisms. Investigating the consequences of Early mitotic inhibitor 1 (Emi1) depletion in human cells, previously associated with rereplication, we show by DNA fiber labeling that origin reactivation occurs rapidly, well before accumulation of cells with >4N DNA, and is associated with checkpoint-blind ssDNA gaps and replication fork reversal. Massive RPA chromatin loading, formation of small chromosomal fragments, and checkpoint activation occur only later, once cells complete bulk DNA replication. We propose that deregulated origin firing leads to undetected discontinuities on newly replicated DNA, which ultimately cause breakage of rereplicating forks. 相似文献
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