BMC医学伦理
Human germline editing in the era of CRISPR-Cas: risk and uncertainty, inter-generational responsibility, therapeutic legitimacy

History was made this year when two women, Jennifer Doudna and Emmanuelle Charpentier, won the Nobel Prize in Chemistry for the development of a genome editing method using CRISPR-Cas9, which has numerous applications in the editing of plant and animal genomes. However, even before the discovery of CRISPR-Cas’ use in DNA editing, the use of genome editing techniques in humans has long been considered unethical, with many countries making it illegal to edit human embryos. In 2018, the highly-controversial birth of the‘CRISPR babies’– twin girls allegedly born with CRISPR-edited genomes – shocked the world and renewed discussions about the ethics and legality of such practices.

使用囊性纤维化场景作为功能示例，Schleidgenet al.探索与CRISPR-CAS有关的人类种系疗法的三个始终如一的问题：在人类种系编辑中使用该工具的风险，未来后代承担的责任以及该治疗是否合法。

作者认为,绝对禁止the use of CRISPR-Cas ‘one-generation germline therapies’ – which would theoretically phenotypically cure the developing embryo, but ensure that the changes are not passed onto offspring – would not be legally or ethically justifiable, provided that concepts surrounding human germline editing are clarified.

BMC医学研究方法
评估偏见的风险：关于观察性研究和随机试验的统一框架的提案

目前尚无统一的准则来帮助个人医疗保健专业人员（和医学生）评估不同研究类型的偏见，这是循证医学实践的重要技能。当前确实存在研究类型特定的工具，例如有助于评估观察性研究中偏见但不能可靠地应用于其他研究类型（例如随机试验）的工具。

Luijendijket al.have identified this gap and also argue that current frameworks are limited in requiring only methodological knowledge to detect bias, as some study aspects may only be appraised using subject-matter knowledge. In order to generate a unified framework, they applied a popular conceptual framework typically used only in observational studies to randomized trials, by defining the research question in terms of study population, intervention and outcome, and using causal diagrams to illustrate how each source of bias can lead to over- or under-estimations of treatment effects. The developed framework allows for the identification of three sources of bias independent of study design: bias due to a common cause, bias due to systematic measurement error, and bias due to a common effect.

BMC微生物学
相对丰度Prevotellagenus within the human gut microbiota of elderly volunteers determines the inter-individual responses to dietary supplementation with wheat bran arabinoxylan-oligosaccharides

人类肠道被许多共生和致病细菌定植，这些细菌构成了肠道微生物组的一部分。由于已经确定人类肠道微生物组的组成可以对我们的健康产生重大影响，因此研究领域迅速发展。在过去的40年中，2013年至2017年之间，有80％的人类肠道微生物组研究发表。双歧杆菌are relatively abundant in the human gut, and attract particular interest due to their potential for use as probiotics (live bacteria that are considered to be good for health) and as targets of prebiotics (substances that increase the abundance or activity of existing bacteria).

在他们的研究中et al.investigated the effect of dietary supplementation of AXOS (arabinoxylan oligosaccharides, which have been demonstrated to promote the abundance of双歧杆菌）在肠道菌群上。他们进行了一项交叉，随机的双盲试验，从而补充了老年志愿者的饮食，并用轴突或麦芽糊精，并测量了它们对粪便细菌和血清参数的影响。

分析的粪便样品显示出增加双歧杆菌observed across the entire cohort in response to AXOS supplementation, independent of the observed inter-individual variation in gut microbiota. However, variation in the levels of baselinePrevotellaspecies of gut bacteria did determine how responsive each patient was to AXOS supplementation. The authors conclude that AXOS supplementation is bifidogenic, suggesting that AXOS may be considered a viable prebiotic option in the elderly, and due to the influence of existing gut bacteria on the bifidogenic response, call for the consideration of microbiota profiling when testing the efficacy of prebiotics.

BMC怀孕和分娩
Electronic cigarettes may not be a “safer alternative” of conventional cigarettes during pregnancy: evidence from the nationally representative PRAMS data

常规的孕期吸烟linked to adverse effects on both mother and baby health, and is amongst one of the leading preventable causes of adverse birth outcomes. The difficulties of quitting smoking during pregnancy have led many to consider alternatives to conventional cigarettes, such as electronic or ‘e’ cigarettes. As they contain fewer toxic chemicals than conventional cigarettes, e-cigarettes are largely believed to have fewer adverse health effects compared to traditional cigarettes, but there is little evidence to support this.

Authors Sooyong Kim and Sanda Cristina Oancea sought to determine whether e-cigarettes are safer in pregnancy than conventional cigarettes, by extracting and analysing data from the PRAMS (Pregnancy Risk Assessment Monitoring System) study cohort, a large study that included data on 55,000 pregnancies. Participants were classified into three groups: complete tobacco abstinence, exclusive conventional cigarette use, and exclusive e-cigarette use, and adverse birth outcomes were defined as low birth weight, preterm birth and ‘small for gestational age’. They found that, when compared to conventional cigarette users, the risk of each adverse birth outcome was not significantly reduced, and e-cigarettes cannot be considered to be safer than conventional cigarettes. Following this, the authors encourage the complete abstinence from all tobacco products during pregnancy.

Top COVID-19 Research

BMC传染病
新冠肺炎: interpreting scientific evidence – uncertainty, confusion and delays

In an Editorial, Julian W Tang, a virologist at the University of Leicester, UK, who contributed to a评论这敦促医疗界和公共卫生当局承认SARS-COV-2的空降传播的潜力，讨论了有关SARS-COV-2等新兴病原体的专家共识及其对公共卫生政策的影响。

BMC医学伦理
低收入和中等收入国家公共卫生中的道德和人权考虑：使用乌干达对COVID-19的大流行的评估

在这篇辩论文章中，作者Barugahareet al.form criteria to appraise emergency public health measures adopted by the Ugandan government from an ethical and human rights perspective, and argue that measures must be ‘effective, strictly necessary, proportionate to the magnitude of the threat, reasonable in the circumstances, equitable, and least restrictive.’

BMC老年人
Decision-making for receiving paid home care for dementia in the time of COVID-19: a qualitative study

吉贝尔et al.have presented the first study which provides insights into the experiences of UK-based unpaid carers receiving paid home care for dementia, both before and during the pandemic.