A systematic review-meta-analysis of chilling interventions and a meta-regression of various processing interventions for Salmonella contamination of chicken

Context

The results of individual studies investigating the efficacy of chilling and other processing interventions on Salmonella prevalence or concentration in broiler chicken carcasses are inconsistent or contradictory.

Objective

Determine efficacy of chilling on reducing Salmonella prevalence or concentration on broiler carcasses using systematic review-meta-analysis, and explore sources of heterogeneity among studies investigating various processing interventions through meta-regression.

Data sources

A comprehensive search included electronic search in six databases, manual search of reference lists of topic-related articles, and consultation with five topic experts to assure that all relevant intervention research was identified.

Study inclusion

Primary intervention research, published in English, encompassing control, challenge, cohort, or before-and-after study designs investigating the efficacy of any chilling or other processing interventions on Salmonella prevalence or concentration in broiler chicken carcasses.

Risk of bias assessment and data extraction

Data pertaining to study methodology and reported results, chilling or other processing intervention parameters, populations sampled and outcomes measured were assessed for methodological soundness and extracted by two independent reviewers using pretested checklists.

Results

Random-effects meta-analyses of immersion chilling with chlorine (n = 9 trials), acetic acid (n = 16) and potable water (n = 13) trended towards reductions in the odds or log₁₀ CFU/ml of Salmonella. Significant heterogeneity (P-value ≤ 0.1 and I² > 25%) precluded the reporting of pooled summary effect estimates. Meta-regression of all processing interventions indicated that serotype, disinfectant type and treatment time and pH were significantly associated with studies reporting reductions in concentration while study design, population sampled, study setting, publication date, intervention and disinfectant type, and treatment pH were significantly associated with studies reporting reductions in prevalence. Methodological and reporting flaws were consistently observed in relevant intervention research as well as a lack of studies conducted under commercial conditions and using Salmonella concentration outcomes.

Conclusions

Chilling may be effective at reducing Salmonella concentration and prevalence, but significant heterogeneity precluded reporting of pooled summary effect estimates for many chilling interventions. Investigations into potential sources of heterogeneity among all processing interventions found that the use of other chemical disinfectants, such as organic acids and surfactants might result in larger reductions in Salmonella contamination than more commonly utilized oxidizing agents like chlorine.     

中国可降解膜覆盖对玉米产量效应的Meta分析

可降解膜是解决农业生产中地膜残留污染的有效措施,但覆盖可降解膜的作物产量效应仍存在较大分歧.该研究以玉米为研究对象,分别以不覆盖和覆盖普通地膜作为覆盖可降解膜的对照,通过检索已发表的相关田间试验数据,利用Meta分析方法定量研究覆盖可降解膜对玉米的产量效应和影响因素.结果表明,在可降解膜和不覆盖组合中,覆盖可降解膜的玉米产量较不覆盖平均提高17.8%(95%置信区间14.8%~20.9%);该组合不存在发表偏倚和极端值.可降解膜和普通地膜组合存在发表偏倚,校正前覆盖可降解膜的玉米产量显著低于覆盖普通地膜(平均相差1.8%),校正后二者差异不显著(置信区间-0.9%~2.7%);该组合也不存在极端值.与不覆盖和覆盖普通地膜相比,覆盖可降解膜的累计平均产量效应均随时间趋于稳定.近5 a来,覆盖可降解膜与覆盖普通地膜的玉米产量差异和变幅均较2000—2010年有所减小.在高海拔、低气温区域,平作和使用0.008 mm厚度降解膜时,更有利于提高可降解膜的增产效应.该研究可为降解膜的大规模推广应用和开发研制提供依据.     

中国不同气候区小麦产量及发育期持续时间对田间增温的响应

【目的】气候变暖对小麦生长发育有重要影响。然而,中国不同气候区小麦生长发育对温度升高的响应程度仍未系统量化。因此,急需阐明不同气候区增温及不同时段增温对小麦产量及发育期持续时间的影响程度,揭示小麦产量及发育期对增温的响应规律。【方法】本文搜集了1990-2017年间已发表的关于中国小麦全生育期田间持续增温条件下小麦产量变化的21篇文献,运用整合分析（Meta-analysis）量化田间不同增温幅度及不同时段增温对中国小麦产量及生育期的影响程度,系统阐明其在不同气候区的差异及规律。【结果】（1）亚热带季风区增温（0-3℃）显著增加小麦产量、千粒重和穗粒数,其平均增幅分别为8.2%、6.3%和4.7%;温带季风区增温（0-3℃）显著增加小麦产量、穗粒数和穗数,其平均增幅分别为6.8%、3.9%和5.5%,而温带大陆性气候区增温（0-3℃）显著降低小麦产量、千粒重和穗粒数,其平均降幅分别为10.2%、5.9%和8.3%。其中,亚热带季风区增温0-2℃,小麦产量显著提高了8.5%,而增温2-3℃时,小麦并未增产;温带季风气候区小麦增产愈为明显,当增温2-3℃时小麦的增产幅度达14.5%;相反,在温带大陆性气候区增温0-2℃和2-3℃时,小麦分别显著减产10.1%和15.9%。（2）亚热带季风区和温带大陆性气候区增温（0-3℃）小麦全生育期持续时间分别缩短了3.3%和7.1%,相反,在温带季风区,增温并未明显改变小麦全生育期持续时间;与此同时温带大陆性气候区和温带季风气候区的生殖期持续时间并无明显变化,而亚热带季风区小麦生殖生长持续时间却显著增加（8.7%）。（3）总体来看（季风气候区所有独立研究结果）夜间增温0-2℃和2-3℃对小麦产量有显著影响,小麦分别增产10.5%和15.0%。【结论】田间增温会显著影响中国粮食主产区小麦产量以及发育期持续时间,但不同气候区及不同时段增温对小麦生长和发育的影响不同。本研究结果可为未来气候变化新态势下中国粮食主产区种植制度优化与合理布局提供科学依据。     

中医治疗肾虚型排卵障碍性不孕症的Meta分析

目的 评价中医治疗肾虚型排卵障碍性不孕症的疗效。方法 通过电子计算机检索中国期刊全文数据库（CNKI）、万方数据库、中国生物医学文献数据库（CBM）及维普（VIP）资讯数据库,查阅从2001年1月1日至2017年5月31日之间国内发表的肾虚型排卵障碍性不孕症相关的临床随机对照试验（RCT）文献,同时对检索的文献进行筛选。使用Jadad评分量表对符合入选标准的随机对照研究进行质量评分,提取有效数据,并使用软件Revman 5.3版进行分析,采用优势比（OR）作为效应合并指标。结果 共纳入21个RCT,1999例病例。纳入RCT的同质性较好,Meta分析结果提示中医治疗肾虚型排卵障碍性不孕症疗效显著,可明显提高妊娠率。漏斗图提示纳入研究可能存在发表偏倚风险。结论 中医治疗肾虚型排卵障碍性不孕症疗效显著。但还需要一些大样本、高质量的RCT临床试验设计来支持此结论。     

中西医结合治疗新生儿脓疱疮临床疗效的Meta分析

目的 通过对相关文献进行Meta分析,系统评价中西医结合治疗新生儿脓疱疮的临床疗效。方法 检索PubMed、Medline、中国期刊全文数据库、维普期刊数据库、中国知网和万方数据库,检索中西医结合治疗新生儿脓疱疮的随机对照研究（RCT）,由两名评价者独立提取资料并进行方法学质量评估,数据分析采用RevMan 5.3软件进行统计分析。结果 共纳入16个RCT,Meta分析结果显示,中西医结合治疗新生儿脓疱疮总有效率Meta分析结果为：[OR=5.59（95% CI：3.81,8.20）,P<0.01],提示中西医结合治疗新生儿脓疱疮总有效率优于单纯西医治疗;中西医结合治疗新生儿脓疱疮显效率Meta分析结果为：[OR=3.57（95% CI：2.41,5.29）,P<0.01],提示中西医结合治疗新生儿脓疱疮显效率高于单纯西医治疗;脓疱症状消失时间Meta分析结果显示：[MD=-1.64（95% CI：-1.88,-1.40）,P<0.01],提示中西医结合治疗新生儿脓疱疮较单纯西医治疗的脓疱消失所需时间更短。结论 中西医结合治疗新生儿脓疱疮的临床疗效较单纯西医治疗临床疗效更好,且痊愈所需时间更少,临床值得推广。     

生物炭对作物氮肥利用率影响的整合分析

为科学施用生物炭、提高氮肥利用率,采用整合分析的方法,收集符合筛选标准的文献33篇,统计了170组包含生物炭配施化肥(BC+NPK)和单施化肥(NPK)处理下作物氮肥利用率的数据,从不同地域、土壤养分、氮肥用量、生物炭特性与施用量、作物种类等方面量化分析生物炭对作物氮肥利用率的影响。结果显示：施用生物炭可以使作物氮肥利用率提高4.76%,其中南方地区生物炭的促进效果最为明显,提高了11.73%。土壤肥力影响生物炭对氮肥利用率的增幅,在土壤pH值、有机质含量、速效氮含量较低的南方地区,施用生物炭对氮肥利用率的提升效果最优,而在有机质含量较高、pH值较高的东北地区,施用生物炭的效果则有所降低;当氮肥施用量≤120 kg/hm2时,生物炭的增效效果最明显,氮肥利用率提高了10.73%。与经济作物相比,粮食作物的氮肥利用率提升效果更为明显,增加了5.71%。生物炭施用量控制在≤1%时,氮肥利用率提高3.43%,木质材料制备的生物炭的提升效果最明显,氮肥利用率提高7.99%;生物炭含氮量>2%时,氮肥利用率提高19.43%;生物炭pH 9~10时氮肥利用率最佳,肥料利用率能够提升5.01%。     

小麦穗粒数QTL整合与元分析

小麦穗粒数是由多基因控制的复杂数量性状。为发掘控制小麦穗粒数(KNS)的真实主效数量性状位点(quantitative trait loci, QTL)，本研究利用生物信息学手段，借助小麦高密度分子标记遗传图谱，对来自不同遗传作图群体的控制小麦穗粒数的163个QTL位点进行图谱整合、映射和元分析。结果表明，目标性状QTL在小麦21条染色体上不均匀分布，在2B染色体上最多，在7D染色体上最少；建立控制小麦KNS的QTL一致性图谱，最终获得35个一致性QTL(meta quantitative trait loci, MQTL)位点及其紧密连锁的候选分子标记，置信区间最小可达到0.55 cM。     

基于Meta分析的中国灌溉冬小麦产量及水分利用效率影响因素研究

【目的】目前针对灌溉冬小麦产量与水分利用效率影响因素的研究大多集中于某一特定区域,研究结果零散,针对上述问题,揭示宏观尺度下灌溉冬小麦产量和水分利用效率的影响因素。【方法】综合已发表的田间试验数据,采用Meta分析方法得出灌溉在不同地区的增产效应和水分效应,在异质性检验的基础上,通过Meta亚组分析探究灌溉定额、降雨量和平均气温等对冬小麦产量和水分利用效率的影响机制。【结果】与生育期不灌溉相比,灌溉使冬小麦总体增产39.34%,水分利用效率提高3.39%;增产率随灌溉定额的增加而增大,增幅最终趋于稳定,水分利用效率随灌溉定额的增加呈先增加后减少的趋势,当灌溉定额>240 mm时,冬小麦相对水分利用效率变化率显著降低11.29%;随着生育期平均温度上升,灌溉冬小麦增产效应显著提高,生育期均温>9℃时,冬小麦增产率高达45.81%;生育期降雨量对灌溉冬小麦产量影响显著,生育期降雨量处于干旱年份时灌溉增产效应最明显,增产率为72.48%。【结论】灌溉定额为60~120 mm更有利于提高冬小麦产量和水分利用效率。     

Prevalence of human visceral leishmaniasis in Iran: A systematic review and meta-analysis

Leishmania infantum is the main cause of human visceral leishmaniasis (HVL; also known as kala-azar) in the Middle East and may be fatal if left untreated. This disease was first reported in 1949 in Iran. Despite marked improvements in hygiene and sanitation conditions, the disease is still endemic in some parts of Iran. It is difficult to determine the current prevalence of HVL in Iran due to the scarcity of comprehensive studies in this regard. In response to this gap, a systematic review and meta-analysis was conducted to gain better understanding of HVL epidemiology in the general population of Iran. English and Persian databases were searched for studies reporting the prevalence and risk factors associated with HVL in the Iranian people from January 1995 to December 2019. The reported data were selected according to inclusion and exclusion criteria. The pooled prevalence of HVL infection and its 95 % confidence intervals were calculated. Quality assessment, heterogeneity testing and publication bias assessment were also done. Literature search revealed 3634 studies, of which 35 studies met our eligibility criteria, with a total of 50,716 individuals. The meta-analysis was performed on 31 out of 35 included studies. The estimated pooled prevalence of HVL infection according to seropositivity was 2% (95 % CI: 1–2%) in the general population of Iran in which western and northern provinces had the lowest and the highest prevalence, 0.5 % (95 %CI, 0.2−0.7%) and 3% (95 %CI, 1–5 %), respectively. The seroprevalence of HVL among females (2%; 95 %CI, 1–2 %) was more than males (1%; 95 %CI, 1–2 %). The ≤10 and >10 years age groups had similar seroprevalence rates (1%, 95 %CI, 1–2 % versus 1%, 95 %CI, 0–1 %, respectively). There was no significant difference in terms of geographic area, age and sex. Of 31 studies included in the meta-analysis, the most common diagnostic test was the direct agglutination test (96.77 %). To the best of our knowledge, this is the first systematic review of the prevalence of HVL in Iran. The results showed a low seroprevalence of HVL infection. However, the lack of published reports of HVL in an area does not exclusively mean the absence of the disease or carrier. We therefore recommend further studies in this regard.