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11.
The effects of retinoic acid (RA) on osteoblastic differentiation and activity were studied in fetal rat calvaria cells cultured for up to 24 days. Fetal bovine serum used for the experiments was treated with an anion-exchange resin to remove endogenous RA. The depletion of RA in the treated serum was confirmed by high-performance liquid chromatography and tritiated RA tracing. Under the culture conditions employed, the continuous presence of RA for 14 days at 10(-9) mol/l or higher decreased both alkaline phosphatase (ALP) activity on day 12 and the number of bone nodules on day 14 in a dose-dependent manner. Short-term (24 h) exposure to RA at 10(-8) mol/l, which is a physiological concentration, decreased and increased the levels of ALP and osteopontin mRNA on day 6, respectively. Retinoic acid at 10(-8) mol/l also increased the level of osteocalcin mRNA on day 12. However, these effects were not obvious at later stages (days 18 and 24). At a high concentration (10(-6) mol/l), RA increased the level of osteopontin mRNA on day 6 and decreased the levels of ALP and osteocalcin mRNA irrespective of culture period. These results suggest that, at physiological concentrations, RA suppresses the differentiation of osteoprogenitor cells and regulates osteoblastic functions. 相似文献
12.
What ethical concerns regarding the application of new antidementia compounds are pertinent to the best interests of patients with Alzheimer's disease and their caregivers? Based on collected preliminary anecdotal accounts, these concerns are important and should be considered carefully by clinicians, researchers, and families. 相似文献
13.
Compared the writing performance of 33 inverted and 37 noninverted left-handed and right-handed writers (undergraduates). Inverted writers wrote as quickly and as well as noninverted writers when writing with the preferred writing posture but were superior to the latter group when performances with the nonpreferred posture were compared. There was no evidence that left-handers with either writing position were faster with the nonpreferred hand, in direct contradiction to R. Gregory and J. Paul's (see record 1981-11652-001) frequently cited claim that inverted left-handers write faster with the nonpreferred hand. Findings are also related to the J. Levy and M. L. Reid (see record 1977-05149-001) model of writing posture and cerebral organization. Results question attempts by educators to discourage use of the inverted writing posture. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
EJ Shpall SM Stemmer L Hami WA Franklin L Shaw HS Bonner SI Bearman WP Peters RC Bast W McCulloch 《Canadian Metallurgical Quarterly》1994,83(11):3132-3137
4-Hydroperoxycyclophosphamide (4-HC), a commonly used marrow-purging agent, is active against many tumors, but is also toxic to normal marrow progenitors. Amifostine (WR-2721) is a sulfhydryl compound with chemoprotectant activity. Preclinical studies using suspensions of bone marrow and breast cancer cells demonstrated that ex vivo treatment with amifostine followed by 4-HC resulted in protection of marrow progenitors, with no compromise in the antitumor effect of 4-HC. This fact stimulated the development of a clinical trial. Bone marrow was harvested from 15 poor-prognosis breast cancer patients and randomly assigned to ex vivo treatment with amifostine followed by 4-HC (amifostine + 4-HC), or treatment with 4-HC alone. High-dose chemotherapy was then administered followed by infusion of the purged autologous bone marrow support (ABMS). Leukocyte engraftment, defined as a white blood cell count > or = 1 x 10(9)/L, was achieved in an average of 26 days for patients whose marrow was purged with amifostine + 4-HC versus 36 days for patients whose marrow was purged with 4-HC alone (P = .032). The average number of platelet transfusions (12 v 29; P = .017) and days of antibiotic therapy (28 v 40; P = .012) were significantly less for patients whose marrow was exposed to amifostine + 4-HC, compared with 4-HC alone. Unpurged backup marrow fractions were infused into three patients whose marrow was purged with 4-HC alone, because of inadequate marrow recovery. None of the patients who received amifostine + 4-HC-purged marrow required a backup marrow fraction. Complete remissions were achieved in 83% of patients with measurable disease, with no difference between the two cohorts. Forty-three percent of patients remained alive and progression-free at a mean of 13 months posttransplant. There was no significant difference in the rate or pattern of relapse for patients whose marrow was purged with amifostine + 4-HC compared with those whose marrow was purged with 4-HC alone. Ex vivo treatment of marrow with amifostine significantly shortens the time to marrow recovery, thereby reducing the risk of myelosuppressive complications in breast cancer patients receiving high-dose chemotherapy and 4-HC-purged ABMS. Since supportive care requirements are also significantly decreased, amifostine may reduce the cost of such therapy. 相似文献
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Element failures increase the sidelobe power level of an array. Reconfiguring the amplitude and phase distribution of the remaining elements can partially compensate for the failed elements and thus reduce the sidelobe level. An algorithm is obtained that yields the reconfigured distribution by minimizing the ratio of the average peak sidelobe power level to the power in the main beam, taking into account the defective elements. The minimization of this nonlinear function is carried out via a conjugate gradient method. The algorithm is applied to the synthesis of sum and difference patterns of planar arrays 相似文献
18.
Laura Peters 《集成电路应用》2006,(6):16-16
涂层的应用导致晶圆上缺陷的增加或者使光刻表现发生变化虽然现在推测浸没光刻技术的量产时间还太早,但是许多公司正在努力确定生产线何时能从干法工艺跃为湿法工艺。根据最近在San Jose举办的 相似文献
19.
It is generally appreciated that the mechanical behavior of granular media depends fundamentally on the interaction of the
constituent particles, and that the validity of numerical models of granular media would be greatly improved with knowledge
of the grain-scale mechanics. However, most supporting experimental work has been conducted on highly idealized materials,
and a limited amount of information exists on grain-scale force–displacement relationships for naturally occurring materials.
To address this shortcoming, we are conducting a program that integrates laboratory experiments on grains of naturally occurring
aggregate with the discrete element modeling method, with the goal of relating the grain-scale physical and mechanical properties
of granular media to bulk behavior. The paper describes the equipment and methods that have been developed to conduct close-loop
controlled, grain-scale experiments under monotonic and cyclic loading conditions, and presents results from an initial set
of experiments on unbonded grains. The implications of the grain-scale results to the discrete element model are discussed.
Discussions center on the applicability of a physically based approach to the mechanics of granular media in general. In light
of future exploration missions and the resulting need to predict the mechanical properties of lunar and planetary regoliths,
the paper examines the potential usefulness of our physically based approach to the problem of predicting the behavior of
the types of materials found in those environments. 相似文献
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