黄芪多糖对猪瘟疫苗免疫效果影响的Meta分析

为了系统评价黄芪多糖对猪瘟疫苗免疫效果的影响,通过检索数据库资料,纳入有关黄芪多糖对猪瘟疫苗免疫效果影响的随机对照试验(共纳入11个对照试验,样本量为244头猪),利用Cochrane Reviewer′s Handbook 5.0评价标准对试验质量进行评价,并使用Revman 5.3进行统计分析。结果显示:黄芪多糖可显著提高血液中的猪瘟抗体水平,同时提高其血液中的IL-2含量,优于单纯免疫组。表明黄芪多糖可通过提高机体的体液免疫和细胞因子水平来增强猪瘟疫苗的免疫效果,效果确切,值得推广应用。     

基于元分析的抗玉米灰斑病QTL比较定位

以玉米遗传连锁图谱IBM2 2008 Neighbors为参考图谱,整合65个抗玉米灰斑病QTL,构建QTL综合图谱。采用元分析方法优化65个QTL,获得11个"一致性"QTL区间,分别位于染色体bin区的1.05、1.06、2.03、2.07、3.02、4.05、5.03、5.05、7.02、8.07、9.03位置,其在遗传连锁图谱上对应的位置分别为442.21、528.27、228.10、478.00、74.65、311.59、169.62、302.35、252.19、422.70、257.93 cM。对两个具有较多报道和较高表型贡献的"一致性"QTL区间bin1.05和bin1.06,从MaizeGDB网站搜索得到324个基因。因抗病基因在结构上具有高度保守性,将324个基因分别与水稻和拟南芥基因组进行同源比对,在bin1.05和bin1.06内分别确定了7个和3个基因作为玉米抗灰斑病候选基因。     

中国典型生态系统土壤硝化强度的整合分析

针对国内外1959年至2013年间发表的2 900篇中国土壤硝化相关论文,获得288组中国土壤硝化强度数据,涉及26个省份,初步构建了开放式的中国土壤硝化信息系统。进一步利用整合分析,评估了土壤理化性质与土壤硝化强度的可能联系。结果表明:不同生态系统之间硝化速率由大到小依次为:农田(NO-3-N 1.39±0.27 mg kg-1d-1)、草地(0.74±0.17)、森林(0.66±0.16)、沙漠(0.17±0.08)、湿地(0.06±0.04)。在统计显著性的前提下,硝化强度与环境因子之间表现出一定的相关性趋势:即硝化强度与p H、有效磷、硝态氮正相关,与有机碳、速效氮和碳氮比负相关。在较大时空尺度下,生态系统类型是土壤硝化过程地理分异规律的最优解释因子,可能在硝化微生物形成与演替过程中发挥了重要作用。     

Association between residential greenness and birth weight: Systematic review and meta-analysis

Birth weight is extensively investigated as an outcome of interacting with greenery in mothers’ living environment, because it is one of the major causes for neonatal and infant mortality, as well as a correlate of some adverse effects in childhood and beyond. Conversely, in modern urban-ecological systems the access to greenery is limited. The aim of this study was to answer the question whether green spaces and generally greenery in the living environment of pregnant women are associated with the birth weight of their infants and what the direction of that effect is. MEDLINE, EMBASE and the Internet were searched for relevant publications in English and Spanish. Eight studies were identified and included in the analyses (total n = 214 940). We report quality effects meta-analyses based on correlation and standardized regression coefficients as estimates of effect size. Neighbourhood greenness within 100-m buffer was weakly and positively associated with birth weight. The pooled correlation coefficient was 0.049 (95% CI: 0.039, 0.059) and the pooled standardized regression coefficient was 0.001 (95% CI: ?0.001, 0.003). There was, however, considerable heterogeneity between the studies. Using more sensitive measures for greenness and taking into account green space functionality and quality, adjusting for environmental exposures, and assessing individual attitudes towards nature, might yield clearer picture, higher statistical power and more precise results in future research. Our findings endorse the emphasis put on urban forestry and landscape management as closely related to public health and propose a more naturalistic, humanitarian and person-centered approach in future studies.     

Meta-analyses including data from observational studies

Observational studies represent a wide group of studies where the disease or condition of interest is naturally occurring and the investigator does not control allocation to interventions or exposures. Observational studies are used to test hypotheses about the efficacy of interventions or about exposure-disease relationships, to estimate incidence or prevalence of conditions, and to assess the sensitivity and specificity of diagnostic assays. Experimental-study designs and randomized controlled trials (RCTs) can also contribute to the body of evidence about such questions. Meta-analyses (either with or without systematic reviews) aim to combine information from primary research studies to better describe the entire body of work. The aim of meta-analyses may be to obtain a summary effect size, or to understand factors that affect effect sizes. In this paper, we discuss the role of observational studies in meta-analysis questions and some factors to consider when deciding whether a meta-analysis should include results from such studies. Our suggestion is that one should only include studies that are not at high risk of inherent bias when calculating a summary effect size. Study design however can be a meaningful variable in assessment of outcome heterogeneity.     

Impacts of grazing on lowland heathland in north-west Europe

Lowland heathland habitats are recognized to be of high conservation value throughout north-west Europe. Current management approaches focus on arresting natural succession to woodland, and include the use of vegetation cutting, burning and grazing by livestock. However, the introduction of grazing has proved controversial, highlighting the need for evidence regarding its effectiveness. A systematic review of the scientific literature was therefore performed, which identified 13 studies with appropriate comparators (such as untreated controls). Meta-analysis of these data indicated that grazing can result in an increase in the ratio of grassland to ericoid shrub cover, but insufficient experimental evidence was available to assess the effectiveness of any other intervention, indicating a lack of replicated studies with controls. Two forms of expert knowledge were also compiled, based on information in the scientific literature excluded from the meta-analysis, and questionnaire responses of heathland managers. While these two evidence sources were generally in close correspondence, beliefs of heathland managers contradicted the scientific literature with respect to the impact of grazing on the ratio of grassland to ericoid shrubs. Incorporating a range of evidence sources in systematic reviews can therefore provide insights into contradictions in the evidence base. While a large majority of practitioners (94%) believe that grazing is an effective management option for lowland heath, evidence for a number of negative impacts on habitat attributes was recorded, highlighting the need for improved monitoring and experimental analysis of the effectiveness of management interventions.     

胺碘酮联合美托洛尔治疗心房颤动有效性及安全性Meta分析

目的 评价胺碘酮联合美托洛尔治疗心房颤动的有效性及安全性。方法 全面检索CNKI中国期刊全文数据库、维普中文科技期刊全文数据库、万方医药期刊数据库、SinoMed、PubMed等数据库,同时手工检索相关杂志。按Cochrane 评价员手册评价符合纳入标准的文献质量,采用Review manager 5.3.5软件进行统计分析。结果 最终共纳入10篇文献,共计940例患者。结果显示,采用胺碘酮联合美托洛尔治疗心房颤动的疗效优于单用美托洛尔（Z=7.63,P<0.01）;对左房内径及射血分数的改善也优于美托洛尔（P<0.01）;但胺碘酮联合美托洛尔组的不良反应发生率高于单用美托洛尔。结论 基于目前证据,胺碘酮联合美托洛尔口服控制心室率、改善左房内径及射血分数的效果显著优于单用美托洛尔,但其安全性逊于美托洛尔。由于本研究所纳入的文献存在质量缺陷、异质性和区域局限性,今后应开展多中心、大样本、双盲、双模拟的随机对照试验以全面评价胺碘酮联合美托洛尔治疗心房颤动的临床疗效和安全性。     

Meta-analysis of the effects of management factors on Miscanthus × giganteus growth and biomass production

Biomass crops in the U.S. have the potential to reduce the dependence on foreign energy supply, to lower net greenhouse emissions, and to diversify agroecosystems. Miscanthus × giganteus has been extensively researched in Europe but the response to key agronomic management factors has not been summarized. In this study we have collected most of the relevant and up to date European literature on the response of dry biomass production to planting density and nitrogen (N) fertilizer and we provide quantitative estimates of the effect of these practices. The data were analyzed through non-linear mixed models which take into account the hierarchical structure of the data due to variability among countries, locations and years. M. × giganteus responded to N fertilizer only after the third growing season and planting density only had a significant effect on the second growing season. The similarity among growth curves, when dry biomass production was analyzed as function of thermal time, shows the stability of the cropping system against other environmental factors.     

Harvest impacts on soil carbon storage in temperate forests

Forest soil carbon (C) storage is a significant component of the global C cycle, and is important for sustaining forest productivity. Although forest management may have substantial impacts on soil C storage, experimental data from forest harvesting studies have not been synthesized recently. To quantify the effects of harvesting on soil C, and to identify sources of variation in soil C responses to harvest, we used meta-analysis to test a database of 432 soil C response ratios drawn from temperate forest harvest studies around the world. Harvesting reduced soil C by an average of 8 ± 3% (95% CI), although numerous sources of variation mediated this significant, overall effect. In particular, we found that C concentrations and C pool sizes responded differently to harvesting, and forest floors were more likely to lose C than mineral soils. Harvesting caused forest floor C storage to decline by a remarkably consistent 30 ± 6%, but losses were significantly smaller in coniferous/mixed stands (−20%) than hardwoods (−36%). Mineral soils showed no significant, overall change in C storage due to harvest, and variation among mineral soils was best explained by soil taxonomy. Alfisols and Spodosols exhibited no significant changes, and Inceptisols and Ultisols lost mineral soil C (−13% and −7%, respectively). However, these C losses were neither permanent nor unavoidable. Controls on variation within orders were not consistent, but included species composition, time, and sampling depth. Temporal patterns and soil C budgets suggest that forest floor C losses probably have a lesser impact on total soil C storage on Alfisols, Inceptisols, and Ultisols than on Spodosols, which store proportionately large amounts of C in forest floors with long C recovery times (50–70 years). Mineral soil C losses on Inceptisols and Ultisols indicate that these orders are vulnerable to significant harvest-induced changes in total soil C storage, but alternative residue management and site preparation techniques, and the passage of time, may mitigate or negate these losses. Key findings of this analysis, including the dependence of forest floor and mineral soil C storage changes on species composition and soil taxonomic order, suggest that further primary research may make it possible to create predictive maps of forest harvesting effects on soil C storage.