Effects of experimental sleep deprivation on aggressive, sexual and maternal behaviour in animals: a systematic review protocol

Development of a Systematic Review Protocol and a Scoping Review of Ultrasound-Induced Immune Effects in Peripheral Tumors

PURPOSE

Publication numbers reporting that ultrasound can stimulate immune reactions in tumors steadily increase. However, the presented data are partially conflicting, and mechanisms are difficult to identify from single publications. These shortcomings can be addressed by a systematic review and meta-analysis of current literature. As a first step, we here present the methodology and protocol for a systematic review to answer the following research question: Does ultrasound alter the immune reaction of peripheral solid tumors in humans and animals compared to control conditions without ultrasound?

PROCEDURES

We designed a protocol to perform a systematic review and meta-analysis. The suitability of the protocol to detect and sort relevant literature was tested using a subset of publications. We extracted study characteristics, ultrasound parameters, and study outcomes to pre-evaluate the differences between publications and present the data as a scoping review.

RESULTS

From 6532 publications detected by our preliminary literature search, 320 were selected for testing our systematic review protocol. Of the latter, 15 publications were eligible for data extraction. There, we found large differences between study characteristics (e.g., tumor type, age) and ultrasound settings (e.g., wavelength 0.5-9.5 MHz, acoustic pressure 0.0001-15,000 W/cm2). Finally, study outcomes included reports on cells of the innate (e.g., dendritic cells, macrophages) and adaptive immune system (e.g., CD8-/CD4-positive T cells).

CONCLUSION

We designed a protocol to identify relevant literature and perform a systematic review and meta-analysis. The differences between extracted features between publications show the necessity for a comprehensive search and selection strategy in the systematic review to get a complete overview of the literature. Meta-analyses of the extracted outcomes can then enable evidence-based conclusions.

Reviewing the animal literature: how to describe and choose between different types of literature reviews

Before starting any (animal) research project, review of the existing literature is good practice. From both the scientific and the ethical perspective, high-quality literature reviews are essential. Literature reviews have many potential advantages besides synthesising the evidence for a research question. First, they can show if a proposed study has already been performed, preventing redundant research. Second, when planning new experiments, reviews can inform the experimental design, thereby increasing the reliability, relevance and efficiency of the study. Third, reviews may even answer research questions using already available data. Multiple definitions of the term literature review co-exist. In this paper, we describe the different steps in the review process, and the risks and benefits of using various methodologies in each step. We then suggest common terminology for different review types: narrative reviews, mapping reviews, scoping reviews, rapid reviews, systematic reviews and umbrella reviews. We recommend which review to select, depending on the research question and available resources. We believe that improved understanding of review methods and terminology will prevent ambiguity and increase appropriate interpretation of the conclusions of reviews.

Effects of sleep deprivation on maternal behaviour in animal models: A systematic review and meta-analysis

Pregnancy is a period of numerous physical and emotional changes in women's lives, including alterations in sleep patterns and worsening of pre-existing sleep disturbances, which possibly lead to impaired postpartum maternal behaviour and mother-infant relationship. The effects of sleep deprivation during pregnancy in maternal behaviour have been evaluated in preclinical studies, but have provided inconsistent results. Thus, in the present study, we aimed to evaluate the effects of sleep deprivation during pregnancy on maternal behaviour of animals through a systematic review and meta-analyses. After a two-step selection process, six articles were included, all of them describing rat studies. The most frequently used method of sleep deprivation was rapid eye movement sleep restriction, using the multiple-platform method. Four meta-analyses were performed, none of them presenting significant impact of sleep deprivation on maternal behaviour, failing to reproduce the results observed in previous clinical studies. In conclusion, our results show a lack of translational applicability of animal models to evaluate the effects of sleep deprivation during pregnancy on maternal behaviour.

Measurement of corticosterone in mice: a protocol for a mapping review

Severity assessment for experiments conducted with laboratory animals is still based mainly on subjective evaluations; evidence-based methods are scarce. Objective measures, amongst which determination of the concentrations of stress hormones, can be used to aid severity assessment. Short-term increases in glucocorticoid concentrations generally reflect healthy responses to stressors, but prolonged increases may indicate impaired welfare. As mice are the most commonly used laboratory animal species, we performed a systematic mapping review of corticosterone measurements in Mus musculus, to provide a full overview of specimen types (e.g. blood, urine, hair, saliva, and milk) and analysis techniques. In this publication, we share our protocol and search strategy, and our rationale for performing this systematic analysis to advance severity assessment. So far, we have screened 13,520 references, and included 5337 on primary studies with measurements of endogenous corticosterone in M. musculus. Data extraction is currently in progress. When finished, this mapping review will be a valuable resource for scientists interested in corticosterone measurements to aid severity assessment. We plan to present the data in a publication and a searchable database, which will allow for even easier retrieval of the relevant literature. These resources will aid implementation of objective measures into severity assessment.