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31.
The effects of citrus flavonoids on P-glycoprotein (P-gp)-mediated drug efflux were examined in human intestinal Caco-2 cells. The cellular accumulation of rhodamine-123 was measured using 10 citrus flavonoids for preliminary screening. Among the flavonoids tested, diosmin significantly increased the accumulation of rhodamine-123 in Caco-2 cells. In the bidirectional transport of digoxin, diosmin increased the apical-to-basal (A-to-B) transport but decreased the basal-to-apical (B-to-A) transport in both concentration- and time-dependent manners. The digoxin transport ratio (B-A/A-B) was estimated to be 2.3 at a concentration of 50 microM of diosmin, which was significantly lower than the 15.2 found in the control. The apparent Ki values for P(app,A-B) and P(app,B-A) were 16.1 and 5.7 microM, respectively. These results demonstrated that diosmin effectively inhibited the P-gp-mediated efflux in Caco-2 cells. Diosmin is one of the main components in citrus fruits, and the intake of food supplements containing this compound may potentially increase the absorption of drugs able to act as P-gp substrates. The clinical relevance of this interaction should be further evaluated using in vivo experiments.  相似文献   
32.
OBJECTIVE: To examine UK country and ethnic variations in infant feeding practices. DESIGN: Cohort study. SETTING: Infants enrolled in the Millennium Cohort Study, born between September 2000 and January 2002. SUBJECTS: A total of 18 150 natural mothers (11 286 (8207 white) living in England) of singleton infants. OUTCOME MEASURES: Breast-feeding initiation, breast-feeding discontinuation and introduction of solid foods before 4 months. EXPLANATORY VARIABLES: Maternal ethnic group, education and social class. RESULTS: Seventy per cent of UK mothers started to breast-feed, of whom 62% stopped before 4 months. Median age at discontinuing breast-feeding was 14, 13, 10 and 6 weeks in Scotland, England, Wales and Northern Ireland, respectively. Thirty-six per cent of UK mothers (34% in England) introduced solids before 4 months. White mothers were more likely to discontinue breast-feeding (62%) and introduce solids early (37%) than most other ethnic minority groups; those stopping before 4 months were more likely to introduce solids early compared with those continuing to breast-feed beyond this age (adjusted rate ratio (95% confidence interval): 1.3 (1.1-1.2)). Educated mothers were less likely to stop breast-feeding before 4 months (white mothers, 0.8 (0.8-0.9); non-white mothers, 0.9 (0.8-1.0)) than those with no/minimal qualifications but, among ethnic minorities, were more likely to introduce solids early (1.3 (1.0-1.6)). Socio-economic status was positively associated with breast-feeding continuation among white women, and with age at introduction of solids among non-white women. CONCLUSIONS: We have identified important geographic, ethnic and social inequalities in breast-feeding continuation and introduction of solids within the UK, many of which have not been reported previously. The factors mediating these associations are complex and merit further study to ensure that interventions proposed to promote maternal adherence to current infant feeding recommendations are appropriate and effective.  相似文献   
33.
娇红2号为红花玉兰系列新品种,具有极高观赏价值,但是红花玉兰娇红2号移栽后缓苗时间较长.为了缩短移栽缓苗期,促进苗木正常生长,尝试对红花玉兰娇红2号施用ABT-1号生根粉和EM菌剂,并分析其苗木生长发育过程,为揭示移栽后苗木生长响应规律及引种推广提供参考.以1年生红花玉兰娇红2号嫁接苗为试验材料,使用不同质量分数的ABT-1号生根粉和EM菌剂进行浸根、浇水试验.设置对照(CK)、A1、A2、A3、A4、B1、B2、B3、B4共9个处理,分别于5月、7月、9月进行生长指标和生理指标测定,分析各处理的苗木生长发育情况.结果 表明:各处理与对照相比,苗木根系生长恢复期缩短和结合体内保护酶系统的正向调节,促进了苗木正常生长;A3处理(ABT-1号生根粉)可缩短缓苗期2个月左右,用生根粉处理比EM菌剂处理的效果要好;A3处理(ABT-1号生根粉)能明显促进移栽苗木根系2-3级细根的分化吸收运输水分和营养,并通过提高净光合速率和调节自身保护酶系统活性,促进苗木恢复正常生长状态,缩短缓苗期2个月左右.  相似文献   
34.
In human or mouse, mature T cells express either CD4 or CD8, resulting in different functions in the periphery. Interestingly, porcine CD4 and CD8 double positive (DP) T cells are present in the blood, and their proportions change from youth to adulthood. However, the features of these cells in swine are poorly understood. We investigated the fate of porcine peripheral T cells based on their functional characteristics, including proliferation and the expression of CD4 and CD8 co-receptors. The results showed that all the populations changed their CD8 expression in a time-dependent manner and porcine T cells had different proliferative pattern from human T cells. The results further revealed that Th2 cytokines were increased later in porcine T cells compared to human T cells upon stimulation with IL-2 + PMA. Collectively, we found that the fate of porcine peripheral T cells is different from that of human T cells, and the changes occur in a time- and stimulation-dependent manner.  相似文献   
35.
36.
Various somatic cell nuclear transfer (SCNT) techniques for mammalian species have been developed to adjust species-specific procedures to oocyte-associated differences among species. Species-specific SCNT protocols may result in different expression levels of developmentally important genes that may affect embryonic development and pregnancy. In the present study, porcine oocytes were treated with demecolcine that facilitated enucleation with protruding genetic material. Enucleation and donor cell injection were performed either simultaneously with a single pipette (simplified one-step SCNT; SONT) or separately with different pipettes (conventional two-step SCNT; CTNT) as the control procedure. After blastocysts from both groups were cultured in vitro, the expression levels of developmentally important genes (OCT4, NANOG, EOMES, CDX2, GLUT-1, PolyA, and HSP70) were analyzed by real-time quantitative polymerase chain reaction. Both the developmental rate according to blastocyst stage as well as the expression levels CDX2, EOMES, and HSP70 were elevated with SONT compared to CTNT. The genes with elevated expression are known to influence trophectoderm formation and heat stress-induced arrest. These results showed that our SONT technique improved the development of SCNT porcine embryos, and increased the expression of genes that are important for placental formation and stress-induced arrest.  相似文献   
37.
Following the increasing public health concerns related to physical inactivity in the population, the relationship between outdoor recreation and public health has been increasingly acknowledged over the last decades. To improve public health, planners and policy-makers aim to provide good accessibility to recreational landscapes to facilitate outdoor recreational activity. At the same time, they are facing development pressure due to urban growth. In order for planners and policy-makers to secure people access to urban and near urban recreational areas, there is a need to map and measure access in a way that is adequate as a basis for decision-making in planning and design processes. Access is often defined as distance, or proximity, from residents’ homes to recreational areas. This paper explores different ways to map and measure distance to recreational areas, and aims to provide better decision support for planners and decision-makers. Moss municipality in Norway serves as a case study. We begin by addressing the meaning of the term ‘recreational landscape’ and how the choice of definition affects the results when mapping recreational areas. We also discuss who we are measuring distance for, and how different user groups will have different thresholds or critical distances affecting their frequency of visits to a recreational area. Last, we explore different methods for measuring distance within a GIS environment. The paper shows how the purpose of the analysis must be decisive when defining recreational landscapes and choosing methods for measuring access to recreational landscape, in order to provide valuable input to planners and policy-makers aiming at enhancing the possibility for outdoor recreation for people.  相似文献   
38.
  1. Understanding the factors driving population structure in marine mammals is needed to evaluate the impacts of previous exploitation, current anthropogenic threats, conservation status, and success of population recovery efforts.
  2. Sperm whales are characterized by a worldwide distribution, low genetic diversity, complex patterns of social and genetic structure that differ significantly within and between ocean basins, and a long history of being commercially whaled. In Australia, sperm whales from the (International Whaling Commission assigned) southern hemisphere ‘Division 5’ stock were very heavily exploited by whaling.
  3. The present study assessed the potential effects of whaling on the genetic diversity of sperm whales in Australia and the population genetic structure of these whales within a global context. A combination of historical and contemporary sperm whale samples (n = 157) were analysed across six regions, from south-eastern Australia (‘Division 6’ stock in the Pacific Ocean) to south-western Australia (‘Division 5’ stock in the Indian Ocean).
  4. Sperm whales sampled from the ‘Division 5’ and ‘Division 6’ stocks belong to the same population based on nuclear and mitochondrial DNA (mtDNA) analyses. Four novel sperm whale mtDNA haplotypes were identified in animals from Australian waters. Levels of genetic diversity were low in Australian sperm whales but were similar to those previously reported for populations in the Indian and Pacific Oceans.
  5. Given the genetic distinctiveness of sperm whales in Australian waters from other regions in the Pacific and Indian Oceans, and the lack of recovery in population numbers, further scientific studies are needed to increase our understanding of population dynamics and the effectiveness of threat management strategies in this species.
  相似文献   
39.
大落差管道的一些技术问题   总被引:1,自引:1,他引:0  
陈庆勋  桑广世 《油气储运》1998,17(12):11-13
针对大落差成品油管道静压过高和动压过大的技术问题,结合郑州-成都成品油管道的实际情况,提出了具体的解决措施。在正常输送过程中,采用变径管设计,以解决动压过大的技术问题,分析了变径管设计的的水力计算结果。由于管道所经过的地区高差较大,为降低静压,停输时进行静压截断,低流量时采用间歇输送。并对防止不满流现象提出了具体措施。  相似文献   
40.
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