Lack of blinding of outcome assessors in animal model experiments implies risk of observer bias

A Systematic Online Living Evidence Summary of experimental Alzheimer's disease research

BACKGROUND

Despite extensive investment, the development of effective treatments for Alzheimer's disease (AD) has been largely unsuccessful. To improve translation, it is crucial to ensure the quality and reproducibility of foundational evidence generated from laboratory models. Systematic reviews play a key role in providing an unbiased overview of the evidence, assessing rigor and reporting, and identifying factors that influence reproducibility. However, the sheer pace of evidence generation is prohibitive to evidence synthesis and assessment.

NEW METHOD

To address these challenges, we have developed AD-SOLES, an integrated workflow of automated tools that collect, curate, and visualise the totality of evidence from in vivo experiments.

RESULTS

AD-SOLES is a publicly accessible interactive dashboard aiming to surface and expose data from in vivo experiments. It summarises the latest evidence, tracks reporting quality and transparency, and allows research users to easily locate evidence relevant to their specific research question.

COMPARISON WITH EXISTING METHODS

Using automated screening methodologies within AD-SOLES, systematic reviews can begin at an accelerated starting point compared to traditional approaches. Furthermore, through text-mining approaches within the full-text of publications, users can identify research of interest using specific models, outcomes, or interventions without relying on details in the title and/or abstract.

CONCLUSIONS

By automating the collection, curation, and visualisation of evidence from in vivo experiments, AD-SOLES addresses the challenges posed by the rapid pace of evidence generation. AD-SOLES aims to offer guidance for research improvement, reduce research waste, highlight knowledge gaps, and support informed decisionmaking for researchers, funders, patients, and the public.

Choice-based severity scale (CSS): assessing the relative severity of procedures from a laboratory animal's perspective

One primary goal of laboratory animal welfare science is to provide a comprehensive severity assessment of the experimental and husbandry procedures or conditions these animals experience. The severity, or degree of suffering, of these conditions experienced by animals are typically scored based on anthropocentric assumptions. We propose to (a) assess an animal's subjective experience of condition severity, and (b) not only rank but scale different conditions in relation to one another using choice-based preference testing. The Choice-based Severity Scale (CSS) utilizes animals' relative preferences for different conditions, which are compared by how much reward is needed to outweigh the perceived severity of a given condition. Thus, this animal-centric approach provides a common scale for condition severity based on the animal's perspective. To assess and test the CSS concept, we offered three opportunistically selected male rhesus macaques (Macaca mulatta) choices between two conditions: performing a cognitive task in a typical neuroscience laboratory setup (laboratory condition) versus the monkey's home environment (cage condition). Our data show a shift in one individual's preference for the cage condition to the laboratory condition when we changed the type of reward provided in the task. Two additional monkeys strongly preferred the cage condition over the laboratory condition, irrespective of reward amount and type. We tested the CSS concept further by showing that monkeys' choices between tasks varying in trial duration can be influenced by the amount of reward provided. Altogether, the CSS concept is built upon laboratory animals' subjective experiences and has the potential to de-anthropomorphize severity assessments, refine experimental protocols, and provide a common framework to assess animal welfare across different domains.

Profiling neuroprotective potential of trehalose in animal models of neurodegenerative diseases: a systematic review

Trehalose, a unique nonreducing crystalline disaccharide, is a potential disease-modifying treatment for neurodegenerative diseases associated with protein misfolding and aggregation due to aging, intrinsic mutations, or autophagy dysregulation. This systematic review summarizes the effects of trehalose on its underlying mechanisms in animal models of selected neurodegenerative disorders (tau pathology, synucleinopathy, polyglutamine tract, and motor neuron diseases). All animal studies on neurodegenerative diseases treated with trehalose published in Medline (accessed via EBSCOhost) and Scopus were considered. Of the 2259 studies screened, 29 met the eligibility criteria. According to the SYstematic Review Center for Laboratory Animal Experiment (SYRCLE) risk of bias tool, we reported 22 out of 29 studies with a high risk of bias. The present findings support the purported role of trehalose in autophagic flux and protein refolding. This review identified several other lesser-known pathways, including modifying amyloid precursor protein processing, inhibition of reactive gliosis, the integrity of the blood-brain barrier, activation of growth factors, upregulation of the downstream antioxidant signaling pathway, and protection against mitochondrial defects. The absence of adverse events and improvements in the outcome parameters were observed in some studies, which supports the transition to human clinical trials. It is possible to conclude that trehalose exerts its neuroprotective effects through both direct and indirect pathways. However, heterogeneous methodologies and outcome measures across the studies rendered it impossible to derive a definitive conclusion. Translational studies on trehalose would need to clarify three important questions: 1) bioavailability with oral administration, 2) optimal time window to confer neuroprotective benefits, and 3) optimal dosage to confer neuroprotection.

Systematic Evaluation of Spinal Cord Injury Animal Models in the Field of Biomaterials

The large number of animal models used in spinal cord injury (SCI) research complicates the objective selection of the most appropriate model to investigate the efficacy of biomaterial-based therapies. This systematic review aims to identify a list of relevant animal models of SCI by evaluating the confirmation of SCI and animal survival in all published SCI models used in biomaterials research up until April 2021. A search in PubMed and Embase based on "spinal cord injury," "animal models," and "biomaterials" yielded 4606 papers, 393 of which were further evaluated. A total of 404 individual animal experiments were identified based on type of SCI, level of SCI, and the sex, species, and strain of the animals used. Finally, a total of 149 unique animal models were comparatively evaluated, which led to the generation of an evidence-based list of well-documented mid-thoracic rat models of SCI. These models were used most often, clearly confirmed SCI, and had relatively high survival rates, and therefore could serve as a future starting point for studying novel biomaterial-based therapies for SCI. Furthermore, the review discusses (1) the possible risk of bias in SCI animal models, (2) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (3) the clinical relevance of the currently utilized models. Systematic review registration: The study was prospectively registered in PROSPERO, registration number CRD42019141162. Impact statement Studies on biomaterial-based therapies within the field of spinal cord injury (SCI) research show a large inconsistency concerning the selection of animal models. This review goes beyond summarizing the existing gaps between experimental and clinical SCI by systematically evaluating all animal models used within this field. The models identified by this work were used most often, clearly confirmed SCI, and had a relatively high survival rate. This evidence-based list of well-documented animal models will serve as a practical guideline in future research on innovative biomaterial-based therapies for SCI.

Scientific and Regulatory Policy Committee Best Practices: Recommended ("Best") Practices for Informed (Non-blinded) Versus Masked (Blinded) Microscopic Evaluation in Animal Toxicity Studies

This article describes the Society of Toxicologic Pathology's (STP) five recommended ("best") practices for appropriate use of informed (non-blinded) versus masked (blinded) microscopic evaluation in animal toxicity studies intended for regulatory review. (1) Informed microscopic evaluation is the default approach for animal toxicity studies. (2) Masked microscopic evaluation has merit for confirming preliminary diagnoses for target organs and/or defining thresholds ("no observed adverse effect level" and similar values) identified during an initial informed evaluation, addressing focused hypotheses, or satisfying guidance or requests from regulatory agencies. (3) If used as the approach for an animal toxicity study to investigate a specific research question, masking of the initial microscopic evaluation should be limited to withholding only information about the group (control or test article-treated) and dose equivalents. (4) The decision regarding whether or not to perform a masked microscopic evaluation is best made by a toxicologic pathologist with relevant experience. (5) Pathology peer review, performed to verify the microscopic diagnoses and interpretations by the study pathologist, should use an informed evaluation approach. The STP maintains that implementing these five best practices has and will continue to consistently deliver robust microscopic data with high sensitivity for animal toxicity studies intended for regulatory review. Consequently, when conducting animal toxicity studies, the advantages of informed microscopic evaluation for maximizing sensitivity outweigh the perceived advantages of minimizing bias through masked microscopic examination.

Glyphosate and neurological outcomes: A systematic literature review of animal studies

Studies of nervous system effects of glyphosate, a widely used herbicide, have not been critically examined. The aim of this paper was to systematically review glyphosate-induced neurotoxicity literature to determine its usefulness in regulatory decision-making. The review was restricted to mammalian studies of behavior, neuropathology, and neuropharmacology; in vitro and other biochemical studies were considered supplementary information. Glyphosate formulation studies were also considered, despite uncertainties regarding toxicities of the formulated products; no studies used a formulation vehicle as the control. Inclusion criteria were developed a priori to ensure consistent evaluation of studies, and in vivo investigations were also ranked using ToxRTool software to determine reliability. There were 27 in vivo studies (open literature and available regulatory reports), but 11 studies were considered unreliable (mostly due to critical methodological deficiencies). There were only seven acceptable investigations on glyphosate alone. Studies differed in terms of dosing scenarios, experimental designs, test species, and commercial product. Limitations included using only one dose and/or one test time, small sample sizes, limited data presentation, and/or overtly toxic doses. While motor activity was the most consistently affected endpoint (10 of 12 studies), there were considerable differences in outcomes. In six investigations, there were no marked neuropathological changes in the central or peripheral nervous system. Other neurological effects were less consistent, and some outcomes were less convincing due to influences including high variability and small effect sizes. Taken together, these studies do not demonstrate a consistent impact of glyphosate on the structure or function of the mammalian nervous system.

What Is the Optimal Timing of Transplantation of Neural Stem Cells in Spinal Cord Injury? A Systematic Review and Network Meta-Analysis Based on Animal Studies

Objective

The optimal transplantation timing of neural stem cells in spinal cord injury is fully explored in animal studies to reduce the risk of transformation to clinical practice and to provide valuable reference for future animal studies and clinical research.

Method

Seven electronic databases, namely, PubMed, Web of Science, Embase, Wanfang, Chinese Scientific Journal Database (CSJD-VIP), China Biomedical Literature Database (CBM), and China National Knowledge Infrastructure (CNKI), were searched. The studies were retrieved from inception to November 2021. Two researchers independently screened the literature, extracted data, and evaluated the methodological quality based on the inclusion criteria.

Results and Discussion

Thirty-nine studies were incorporated into the final analyses. Based on the subgroup of animal models and transplantation dose, the results of network meta-analysis showed that the effect of transplantation in the subacute phase might be the best. However, the results of traditional meta-analysis were inconsistent. In the moderate-dose group of moderate spinal cord injury model and the low-dose group of severe spinal cord injury model, transplantation in the subacute phase did not significantly improve motor function. Given the lack of evidence for direct comparison between different transplantation phases, the indirectness of our network meta-analysis, and the low quality of evidence in current animal studies, our confidence in recommending cell transplantation in the subacute phase is limited. In the future, more high-quality, direct comparative studies are needed to explore this issue in depth.

Structure-Function Relationships in the Rodent Streptozotocin-Induced Model for Diabetic Retinopathy: A Systematic Review

The streptozotocin (STZ)-induced rodent model is one of the most commonly employed models in preclinical drug discovery for diabetic retinopathy (DR). However, standardization and validation of experimental readouts are largely lacking. The aim of this systematic review was to identify and compare the most useful readouts of STZ-induced DR and provide recommendations for future study design based on our findings. We performed a systematic search using 2 major databases, PubMed and EMBASE. Only articles describing STZ-induced DR describing both functional and structural readouts were selected. We also assessed the risk of bias and analyzed qualitative data in the selected studies. We identified 21 studies that met our inclusion/exclusion criteria, using either rats or mice and study periods of 2 to 24 weeks. Glucose level thresholds used to define hyperglycemia were inconsistent between studies, however, most studies used either 250 or 300.6 mg/dL as a defining criterion for hyperglycemia. All included studies performed electroretinography (ERG) and reported a reduction in a-, b-, or c-wave and/or oscillatory potential amplitudes. Spectral-domain optical coherence tomography and fluorescein angiography, as well as immunohistochemical and histopathological analyses showed reductions in retinal thickness, vascular changes, and presence of inflammation. Risk of bias assessment showed that all studies had a high risk of bias due to lack of reporting or correctly following procedures. Our systematic review highlights that ERG represents the most consistent functional readout in the STZ model. However, due to the high risk of bias, caution must be used when interpreting these studies.

Weaknesses in Experimental Design and Reporting Decrease the Likelihood of Reproducibility and Generalization of Recent Cardiovascular Research

Recent evidence indicates that many clinical and preclinical studies are not reproducible. Prominent causes include design and implementation issues, low statistical power, unintentional bias, and incomplete reporting in the published literature. The primary goal of this study was to assess the quality of published research in three prominent cardiovascular research journals by examining statistical power and assessing the adherence to augmented ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments). For unpaired t-tests, the average median power for a 20% and 50% change was 0.27 ± 0.06 and 0.88 ± 0.08, respectively. For analysis of guidelines, 40 categories were assessed with a 0-2 scale. Although many strengths were observed, several key elements that were needed for reproducibility were inadequate, including differentiation of primary and secondary outcomes, power calculations for group size, allocation methods, use of randomization and blinding, checks for normality, reports of attrition, and adverse events of subjects, and assessment of bias. A secondary goal was to examine whether a required checklist improved the quality of reporting; those results indicated that a checklist improved compliance and quality of reporting, but adequacy levels in key categories were still too low. Overall, the findings of this study indicated that the probability for reproducibility of many clinical and preclinical cardiovascular research studies was low because of incomplete reporting, low statistical power, and lack of research practices that decrease experimental bias. Expansion of group sizes to increase power, use of detailed checklists, and closer monitoring for checklist adherence by editors and journals should remediate many of these deficits and increase the likelihood of reproducibility.

Current status of neuroprotective and neuroregenerative strategies in multiple sclerosis: A systematic review

BACKGROUND

Immune-mediated demyelination and consequent degeneration of oligodendrocytes and axons are hallmark features of multiple sclerosis (MS). Remyelination declines in progressive MS, causing permanent axonal loss and irreversible disabilities. Strategies aimed at enhancing remyelination are critical to attenuate disease progression.

OBJECTIVE

We systematically reviewed recent advances in neuroprotective and regenerative therapies for MS, covering preclinical and clinical studies.

METHODS

We searched three biomedical databases using defined keywords. Two authors independently reviewed articles for inclusion based on pre-specified criteria. The data were extracted from each study and assessed for risk of bias.

RESULTS

Our search identified 7351 studies from 2014 to 2020, of which 221 met the defined criteria. These studies reported 262 interventions, wherein 92% were evaluated in animal models. These interventions comprised protein, RNA, lipid and cellular biologics, small molecules, inorganic compounds, and dietary and physiological interventions. Small molecules were the most highly represented strategy, followed by antibody therapies and stem cell transplantation.

CONCLUSION

While significant strides have been made to develop regenerative treatments for MS, the current evidence illustrates a skewed representation of the types of strategies that advance to clinical trials. Further examination is thus required to address current barriers to implementing experimental treatments in clinical settings.

Non-surgical correction of gummy smile using temporary skeletal mini-screw anchorage devices: A systematic review

Background

There are no studies that have systematically reviewed randomized control trials and/or prospective cohort studies that have assessed the significance of temporary skeletal mini-screw anchorage devices (TSAD) for the correction of gummy-smile. The aim of the present systematic review was to assess the significance of non-surgical correction of gummy smile using TSAD.

Material and Methods

The addressed focused question was “Are temporary skeletal mini-screw anchorage devices effective for the correction of gummy smile?” Indexed databases were searched up to and including May 2020. Different combinations of the following key-indexing terms were used: anchorage; gummy smile, mini-screw; orthodontic; and vertical maxillary excess. The literature search was performed without time and language barriers. Randomized clinical trials and prospective cohort studies that addressed the focused questions were included. Risk of bias was assessed using the Downs and Black and Cochran collaboration tools. Letters to the Editor, commentaries, case-reports/series and articles published in non-indexed databases were excluded.

Results

The initial search yielded 2118 studies out of which, four studies met the inclusion criteria and were processed for data extraction. All studies had a prospective research design. One study was a clinical trial and 3 had a non-randomized design. Results of the clinical trial showed no statistically significant difference in the extent of intrusion between the test- and control-groups. The non-randomized studies showed that TSAD are useful in reducing deep overbite. All studies had a high risk of bias.

Conclusions

The TSAD are an effective and practical option in facilitating reduction of excessive gingival display or gummy-smile. However, further long-term follow-up, well-designed and power-adjusted clinical trials are warranted in this regard.

Key words:Anchorage, Excessive gingival display, Gummy-smile, Mini-screw.

Biomonitoring and Digital Data Technology as an Opportunity for Enhancing Animal Study Translation

The failure of animal studies to translate to effective clinical therapeutics has driven efforts to identify underlying cause and develop solutions that improve the reproducibility and translatability of preclinical research. Common issues revolve around study design, analysis, and reporting as well as standardization between preclinical and clinical endpoints. To address these needs, recent advancements in digital technology, including biomonitoring of digital biomarkers, development of software systems and database technologies, as well as application of artificial intelligence to preclinical datasets can be used to increase the translational relevance of preclinical animal research. In this review, we will describe how a number of innovative digital technologies are being applied to overcome recurring challenges in study design, execution, and data sharing as well as improving scientific outcome measures. Examples of how these technologies are applied to specific therapeutic areas are provided. Digital technologies can enhance the quality of preclinical research and encourage scientific collaboration, thus accelerating the development of novel therapeutics.

Evaluating reliability and risk of bias of in vivo animal data for risk assessment of chemicals - Exploring the use of the SciRAP tool in a systematic review context

Within the field of health risk assessment, it is essential that evaluations of reliability or validity of toxicity data are conducted with structure and transparency. To this end, different tools for evaluating toxicity studies have been developed by different groups and organizations, for different specific purposes. The Science in Risk Assessment and Policy (SciRAP) tool was developed for use in the regulatory health risk assessment of chemicals and to promote structured and transparent evaluation of study reliability within European regulatory frameworks. As such, the SciRAP tool is not specifically tailored for use in a systematic review context. However, in light of the current movement towards applying systematic review in the field of environmental health and chemical assessments and European chemicals regulation, we were interested in exploring how SciRAP could be applied in such a context. To achieve this, the scope of the SciRAP tool was first compared to two tools developed based on systematic review principles at the US Environmental Protection Agency's IRIS program and the National Toxicology Program's Office of Health Assessment and Translation (OHAT). Next, the SciRAP and IRIS tools were both applied in a case study to evaluate the same nine in vivo animal studies and the resulting evaluations were compared. The SciRAP tool was found to address the majority of the elements included for study evaluation in the OHAT and IRIS tools. In the case study, no major differences were found in the conclusions drawn when using SciRAP or IRIS tools. However, future developments to bring the SciRAP tool more in line with systematic review principles were identified and are discussed. Overall, this work illustrates the advantages of applying structured and pre-defined methods for study evaluation and provides a unique case study comparing the impact of using different tools for evaluating animal toxicity studies.

Impact of interprofessional collaboration on chronic disease management: Findings from a systematic review of clinical trial and meta-analysis

Improvement of chronic disease management demands effective collaborative relationships between health and social-care which is achieved through teamwork. Interprofessional Education (IPE) and Interprofessional Collaboration (IPC) are recognized as essential for the delivery of effective and efficient healthcare. Although IPC and IPE are key components of primary care, evidence of studies evaluating how an IPE intervention prior to IPC improved chronic patient outcomes remains scarce. The aim of this study was to assess the impact of IPC interventions on the management of chronic patients compared to usual care. A systematic review and meta-analysis of Randomized Controlled Trials (RCTs) on IPC interventions on chronicity management and their impact on clinical and process outcomes was conducted. Of the 11,128 papers initially retrieved, 23 met the inclusion criteria. Meta-analyses results showed the reduction of systolic blood pressure (Mean Difference (MD) -3.70; 95 % CI -7.39, -0.01), glycosylated hemoglobin (MD -0.20; 95 % CI -0.47, -0.07), LDL cholesterol (MD -5.74; 95 % CI -9.34, -2.14), diastolic blood pressure (MD -1.95; 95 % CI -3.18, -0.72), days of hospitalization (MD -2.22; 95 % CI -4.30, -0.140). A number of positive findings for outcomes related to IPC were found reflecting an improvement of quality of care and an enhancement in the delivery of patient-centered and coordinated care. Moreover, the need for a purposeful systemic approach linking interprofessional education with interprofessional collaboration and patient health and wellbeing is necessary.

Identification of TGFβ signatures in six murine models mimicking different osteoarthritis clinical phenotypes

OBJECTIVE

TGFβ is a key player in cartilage homeostasis and OA pathology. However, few data are available on the role of TGFβ signalling in the different OA phenotypes. Here, we analysed the TGFβ pathway by transcriptomic analysis in six mouse models of OA.

METHOD

We have brought together seven expert laboratories in OA pathophysiology and, used inter-laboratories standard operating procedures and quality controls to increase experimental reproducibility and decrease bias. As none of the available OA models covers the complexity and heterogeneity of the human disease, we used six different murine models of knee OA: from post-traumatic/mechanical models (meniscectomy (MNX), MNX and hypergravity (HG-MNX), MNX and high fat diet (HF-MNX), MNX and seipin knock-out (SP-MNX)) to aging-related OA and inflammatory OA (collagenase-induced OA (CIOA)). Four controls (MNX-sham, young, SP-sham, CIOA-sham) were added. OsteoArthritis Research Society International (OARSI)-based scoring of femoral condyles and ribonucleic acid (RNA) extraction from tibial plateau samples were done by single operators as well as the transcriptomic analysis of the TGFβ family pathway by Custom TaqMan® Array Microfluidic Cards.

RESULTS

The transcriptomic analysis revealed specific gene signatures in each of the six models; however, no gene was deregulated in all six OA models. Of interest, we found that the combinatorial Gdf5-Cd36-Ltbp4 signature might discriminate distinct subgroups of OA: Cd36 upregulation is a hallmark of MNX-related OA while Gdf5 and Ltbp4 upregulation is related to MNX-induced OA and CIOA.

CONCLUSION

These findings stress the OA animal model heterogeneity and the need of caution when extrapolating results from one model to another.

SPiDbox: design and validation of an open-source "Skinner-box" system for the study of jumping spiders

BACKGROUND

Skinner-box systems are fundamental in behavioural research. They are objective, reliable and can be used to carry out procedures otherwise impossible with manual methodologies. Recently, jumping spiders have caught the interest of scientists for their remarkable cognitive abilities. However, inquiries on their learning abilities are still few, since we lacked a proper methodology capable of overcoming the inherent difficulties that this family poses when carrying out a conditioning protocol.

NEW METHOD

In this paper, a new, automated, open-source Skinner-box, intended for the study of jumping spiders is presented. The system is 3d printable, cheap, fully open-source; is controlled with a Raspberry Pi Zero by a Python script. Since spiders are too lightweight to activate large physical object, the SPiDbox employs photo-sensors.

RESULTS

To validate the methodology, 30 Phidippus regius underwent a training procedure for a simple discrimination task to validate the effectiveness of the system. The spiders managed to learn the task, establishing the effectiveness of the SPiDbox.

COMPARISON WITH EXISTING METHODS

This automated training appears to be more reliable and effective than traditional methodologies. Moreover, its highly scalable, as many SPiDboxes could be used in parallel.

CONCLUSIONS

The SPiDbox appears to be an effective system to train jumping spiders, opening up the possibility to study learning in increasingly more complex tasks, possibly extending our understanding of jumping spiders' cognitive abilities.

Role of Probiotics in Oral Health Maintenance Among Patients Undergoing Fixed Orthodontic Therapy: a Systematic Review of Randomized Controlled Clinical Trials

The aim was to assess the role of probiotics in oral health maintenance among patients undergoing fixed orthodontic therapy (OT). An unrestricted search of indexed databases was performed until April 2020 using the following Mesh-terms: (1) probiotic and (2) orthodontic. Randomized controlled clinical trials (RCTs) evaluating the influence of probiotic therapy (PT) towards oral health maintenance/improvement in patients undergoing fixed OT were included. Data screening, selection, and extraction were performed; and the risk of bias was assessed using the Cochrane Collaboration's tool. All evaluations were performed by 2 independent researchers; and disagreements were resolved via discussion. Nine RCTs were included. Eight studies reported that PT improves oral health in patients undergoing fixed OT. Seven studies showed that PT reduces the counts of oral pathogenic bacteria in the oral biofilm and/or saliva. One study reported that PT reduces halitosis in patients undergoing fixed OT. One study found that PT reduces the scores of plaque index (PI) and gingival index (GI); and one study reported that PT has no significant influence on PI and GI in patients undergoing fixed OT. One study reported that PT does not prevent the formation of white spot lesions during fixed OT. Three and 6 studies had a moderate and low risk of bias, respectively. A power analysis was performed in 4 studies. In conclusion, probiotics exhibit antimicrobial activity against oral pathogenic bacteria; however, due to the limitations of the studies assessed, further well-designed RCTs are needed.

ICNIRP Note: Critical Evaluation of Two Radiofrequency Electromagnetic Field Animal Carcinogenicity Studies Published in 2018

Final results are now available from two large animal studies that investigated whether long-term exposure to radiofrequency (RF) electromagnetic fields (EMFs) associated with mobile (or cell) phones or base stations is carcinogenic; these studies hale from the US National Toxicology Program (NTP) and the Ramazzini Institute in Italy, respectively. In both cases, the authors concluded that they had demonstrated that RF EMFs are carcinogenic in male rats but not in female rats or mice (NTP only). The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has evaluated their methods and findings for potential information about the carcinogenicity of exposure to RF EMFs. We found that these studies had important strengths; for example, both followed good laboratory practice (GLP), both used much larger numbers of animals than previous research, and both exposed animals over the whole of their lives. We also noted some major weaknesses, including a lack of blinding, difficulties interpreting statistical analyses due to the association between longer lifespans and tumor occurrence in the exposed rats (NTP only), and failure to account for chance. ICNIRP concluded that these substantial limitations preclude conclusions being drawn concerning RF EMFs and carcinogenesis.

Opinion on Current Use of Non-Blinded Versus Blinded Histopathologic Evaluation in Animal Toxicity Studies

The Society of Toxicologic Pathology (STP) explored current institutional practices for selecting between non-blinded versus blinded histopathologic evaluation during Good Laboratory Practice (GLP)-compliant, regulatory-type animal toxicity studies using a multi-question survey and STP-wide discussion (held at the 2019 STP annual meeting). Survey responses were received from 107 individuals representing 83 institutions that collectively employ 589 toxicologic pathologists. Most responses came from industry (N = 46, mainly biopharmaceutical or contract research organizations) and consultants (N = 24). For GLP-compliant animal toxicity studies, histopathologic evaluation usually involves initial (primary) non-blinded analysis, with post hoc informal blinded re-examination at the study pathologist's discretion to confirm subtle findings or establish thresholds. Initial blinded histopathologic evaluation sometimes is chosen by study pathologists to test formal hypotheses and/or by sponsors to address non-pathologist expectations about histopathology data objectivity. Current practice is that a blinded histopathologic evaluation is documented only if formal blinding (ie, using slides with coded labels) is employed, using simple statements without detailed methodology in the study protocol (or an amendment) and/or pathology report. Blinding is not an appropriate strategy for the initial histopathologic evaluation performed during pathology peer reviews of GLP-compliant animal toxicity studies. [Box: see text].

Systematic review of guidelines for internal validity in the design, conduct and analysis of preclinical biomedical experiments involving laboratory animals

Over the last two decades, awareness of the negative repercussions of flaws in the planning, conduct and reporting of preclinical research involving experimental animals has been growing. Several initiatives have set out to increase transparency and internal validity of preclinical studies, mostly publishing expert consensus and experience. While many of the points raised in these various guidelines are identical or similar, they differ in detail and rigour. Most of them focus on reporting, only few of them cover the planning and conduct of studies. The aim of this systematic review is to identify existing experimental design, conduct, analysis and reporting guidelines relating to preclinical animal research. A systematic search in PubMed, Embase and Web of Science retrieved 13 863 unique results. After screening these on title and abstract, 613 papers entered the full-text assessment stage, from which 60 papers were retained. From these, we extracted unique 58 recommendations on the planning, conduct and reporting of preclinical animal studies. Sample size calculations, adequate statistical methods, concealed and randomised allocation of animals to treatment, blinded outcome assessment and recording of animal flow through the experiment were recommended in more than half of the publications. While we consider these recommendations to be valuable, there is a striking lack of experimental evidence on their importance and relative effect on experiments and effect sizes.

Acupuncture at Zusanli (ST36) for Experimental Sepsis: A Systematic Review

Background

Sepsis is a global major health problem with high mortality rates. More effective therapy is needed for treating sepsis. Acupuncture has been used for various diseases, including severe infection, in China for more than 2,000 years. Previous studies reported that acupuncture at Zusanli (ST36) might be effective in treating sepsis, but the efficacy and the quality of evidence remain unclear since there is no systematic review on acupuncture at ST36 for sepsis.

Methods

Seven databases were searched from the inception of each database up to May 2019. Ultimately, 54 studies using acupuncture at ST36 for the treatment of experimental sepsis were identified in both English and Chinese literature with systematic review procedures.

Results

Acupuncture might be useful in reducing injuries induced by sepsis in cardiac, lung, kidney, liver, gastrointestinal tract, and immune system. Its potential mechanisms for antisepsis might include reducing oxidative stress and inflammation, improving microcirculatory disturbance, and maintaining the immune balance mediated by dopamine. However, the positive findings should be interpreted with caution due to poor methodological quality and publication bias.

Conclusion

Acupuncture at ST36 might be a promising complementary strategy for controlling sepsis inflammation, yet further studies are needed.

Reproducibility and Rigor in Animal-Based Research

Increasing focus on issues of research reproducibility affords us the opportunity to review some of the key issues related in vivo research. First, we set out some key definitions, to guide the reader through the rest of the paper. Next we consider issues of epistemology, of how animal experiments lead to changes in our understanding of biomedicine and, potentially, to the development of new therapeutics. Here we consider the meaning of statistical significance; the importance of understanding whether findings have general truth; and the advances in knowledge which can result from 'failed' replication. Then, we consider weaknesses in the design, conduct and reporting of experiments, and review evidence for this from systematic reviews and from experimental studies addressing these issues. We consider the impact that these weaknesses have on the development of new treatments for human disease, and reflect on the response to these issues from the biomedical research community. Finally, we consider strategies for improvement including increased use of brief, pre-registered study protocols; pre-registration, open publication and open data; and the central importance of education in improving research performance.

Minimum Information in In Vivo Research

Data quality, reproducibility and reliability are a matter of concern in many scientific fields including biomedical research. Robust, reproducible data and scientific rigour form the foundation on which future studies are built and determine the pace of knowledge gain and the time needed to develop new and innovative drugs that provide benefit to patients. Critical to the attainment of this is the precise and transparent reporting of data. In the current chapter, we will describe literature highlighting factors that constitute the minimum information that is needed to be included in the reporting of in vivo research. The main part of the chapter will focus on the minimum information that is essential for reporting in a scientific publication. In addition, we will present a table distinguishing information necessary to be recorded in a laboratory notebook or another form of internal protocols versus information that should be reported in a paper. We will use examples from the behavioural literature, in vivo studies where the use of anaesthetics and analgesics are used and finally ex vivo studies including histological evaluations and biochemical assays.

Influence of increased body mass index on orthodontic tooth movement and related parameters in children and adolescents: A systematic review of longitudinal controlled clinical studies

Objectives:

To assess the impact of increased body mass index (BMI) on orthodontic tooth movement (OTM) and related parameters in children and adolescents.

Search sources:

A search of six electronic databases and manual searching were performed up to June 2019 without language and time restrictions.

Data selection:

Eligibility criteria were as follows: (1) longitudinal controlled clinical studies; (2) children and adolescents undergoing orthodontic therapy (OT); (3) no systemic diseases; (4) experimental group: patients with increased BMI; and (5) control group: patients with normal BMI.

Data extraction:

Screening, study selection and data extraction were performed; bias within studies was assessed using the Risk of Bias In Non-randomised Studies (ROBINS-I) tool.

Results:

Seven studies were included. One study showed that an increased BMI is associated with less wear-time of removable orthodontic appliances and one study found no significant association. One study showed that an increased BMI is associated with less cooperation during OT; however, not with the treatment results. One study reported higher pain experience during OT in adolescents with than without increased BMI. Two studies showed that increased BMI in adolescents is related to OTM, one with increased and one with decreased rates of OTM, respectively. One study reported an association between increased BMI and incidence of white spot lesions and gingivitis during OT. The ROBINS-I tool showed low to moderate risk of bias within studies.

Conclusions:

The influence of BMI on OTM and related parameters in children and adolescents remains debatable.

A novel vibration-induced exercise paradigm improves fitness and lipid metabolism of Caenorhabditis elegans

Exercise has been known to reduce the risk of obesity and metabolic syndrome, but the mechanisms underlying many exercise benefits remain unclear. This is, in part, due to a lack of exercise paradigms in invertebrate model organisms that would allow rapid mechanistic studies to be conducted. Here we report a novel exercise paradigm in Caenorhabditis elegans (C. elegans) that can be implemented under standard laboratory conditions. Mechanical stimulus in the form of vibration was transduced to C. elegans grown on solid agar media using an acoustic actuator. One day post-exercise, the exercised animals showed greater physical fitness compared to the un-exercised controls. Despite having higher mitochondrial reactive oxygen species levels, no mitohormetic adaptations and lifespan extension were observed in the exercised animals. Nonetheless, exercised animals showed lower triacylglycerides (TAG) accumulation than the controls. Among the individual TAG species, the most significant changes were found in mono- and polyunsaturated fatty acid residues. Such alteration resulted in an overall lower double bond index and peroxidation index which measure susceptibility towards lipid peroxidation. These observations are consistent with findings from mammalian exercise literature, suggesting that exercise benefits are largely conserved across different animal models.

Animal models of cardiac arrest: A systematic review of bias and reporting

AIM OF THE REVIEW

Animal models are essential in advancing resuscitation research but are susceptible to various biases compromising internal validity, which may explain unsuccessful transition to human clinical trials. This study aimed to assess risk of bias in animal studies of cardiac arrest.

DATA SOURCES

This study was based on a previous systematic review of all animal cardiac arrest studies published between March 8, 2011 and March 8, 2016 in PubMed and EMBASE. For this study, we focused on interventional studies and selected a random sample of 50 pig and 50 rat studies. We used a modified version of the SYRCLE's risk of bias tool for animal studies. Bias assessment was performed by two independent reviewers.

RESULTS

92% of pig studies and 88% of rat studies used randomization to assign interventions, but the methodology was unknown or insufficiently reported in 60% and 68% of the studies, respectively. Correct timing of randomization was lacking or unclear in over half of the studies. 40% of pig studies and 28% of rat studies reported insufficient baseline characteristics. When possible, blinding was not performed/reported in 68% of rat studies and 31% of pig studies. Blinding of outcome assessors was missing or inadequately reported in 65% of pig studies and 60% of rat studies. 80% of all studies lacked a sample size calculation, while 60% of pig and 80% of rat studies omitted a specified primary outcome.

CONCLUSION

This study indicates insufficient reporting and methodological shortcomings in animal models of cardiac arrest.

The Weak Spots in Contemporary Science (and How to Fix Them)

In this review, the author discusses several of the weak spots in contemporary science, including scientific misconduct, the problems of post hoc hypothesizing (HARKing), outcome switching, theoretical bloopers in formulating research questions and hypotheses, selective reading of the literature, selective citing of previous results, improper blinding and other design failures, p-hacking or researchers' tendency to analyze data in many different ways to find positive (typically significant) results, errors and biases in the reporting of results, and publication bias. The author presents some empirical results highlighting problems that lower the trustworthiness of reported results in scientific literatures, including that of animal welfare studies. Some of the underlying causes of these biases are discussed based on the notion that researchers are only human and hence are not immune to confirmation bias, hindsight bias, and minor ethical transgressions. The author discusses solutions in the form of enhanced transparency, sharing of data and materials, (post-publication) peer review, pre-registration, registered reports, improved training, reporting guidelines, replication, dealing with publication bias, alternative inferential techniques, power, and other statistical tools.

Augmented cartilage regeneration by implantation of cellular versus acellular implants after bone marrow stimulation: a systematic review and meta-analysis of animal studies

Bone marrow stimulation may be applied to regenerate focal cartilage defects, but generally results in transient clinical improvement and formation of fibrocartilage rather than hyaline cartilage. Tissue engineering and regenerative medicine strive to develop new solutions to regenerate hyaline cartilage tissue. This systematic review and meta-analysis provides a comprehensive overview of current literature and assesses the efficacy of articular cartilage regeneration by implantation of cell-laden versus cell-free biomaterials in the knee and ankle joint in animals after bone marrow stimulation. PubMed and EMBASE (via OvidSP) were systematically searched using tissue engineering, cartilage and animals search strategies. Included were primary studies in which cellular and acellular biomaterials were implanted after applying bone marrow stimulation in the knee or ankle joint in healthy animals. Study characteristics were tabulated and outcome data were collected for meta-analysis for studies applying semi-quantitative histology as outcome measure (117 studies). Cartilage regeneration was expressed on an absolute 0–100% scale and random effects meta-analyses were performed. Implantation of cellular biomaterials significantly improved cartilage regeneration by 18.6% compared to acellular biomaterials. No significant differences were found between biomaterials loaded with stem cells and those loaded with somatic cells. Culture conditions of cells did not affect cartilage regeneration. Cartilage formation was reduced with adipose-derived stem cells compared to other cell types, but still improved compared to acellular scaffolds. Assessment of the risk of bias was impaired due to incomplete reporting for most studies. Implantation of cellular biomaterials improves cartilage regeneration compared to acellular biomaterials.

Accelerating Biomedical Discoveries through Rigor and Transparency

Difficulties in reproducing published research findings have garnered a lot of press in recent years. As a funder of biomedical research, the National Institutes of Health (NIH) has taken measures to address underlying causes of low reproducibility. Extensive deliberations resulted in a policy, released in 2015, to enhance reproducibility through rigor and transparency. We briefly explain what led to the policy, describe its elements, provide examples and resources for the biomedical research community, and discuss the potential impact of the policy on translatability with a focus on research using animal models. Importantly, while increased attention to rigor and transparency may lead to an increase in the number of laboratory animals used in the near term, it will lead to more efficient and productive use of such resources in the long run. The translational value of animal studies will be improved through more rigorous assessment of experimental variables and data, leading to better assessments of the translational potential of animal models, for the benefit of the research community and society.

Comparing reliabilities of strip and conventional patch testing

BACKGROUND

The standardized protocol for performing the strip patch test has proven to be valid, but evidence on its reliability is still missing.

OBJECTIVE

To estimate the parallel-test reliability of the strip patch test as compared with the conventional patch test.

METHODS

In this multicentre, prospective, randomized, investigator-blinded reliability study, 132 subjects were enrolled. Simultaneous duplicate strip and conventional patch tests were performed with the Finn Chambers^® on Scanpor^® tape test system and the patch test preparations nickel sulfate 5% pet., potassium dichromate 0.5% pet., and lanolin alcohol 30% pet. Reliability was estimated by the use of Cohen's kappa coefficient.

RESULTS

Parallel-test reliability values of the three standard patch test preparations turned out to be acceptable, with slight advantages for the strip patch test. The differences in reliability were 9% (95%CI: -8% to 26%) for nickel sulfate and 23% (95%CI: -16% to 63%) for potassium dichromate, both favouring the strip patch test.

CONCLUSIONS

The standardized strip patch test method for the detection of allergic contact sensitization in patients with suspected allergic contact dermatitis is reliable. Its application in routine clinical practice can be recommended, especially if the conventional patch test result is presumably false negative.

Identification of a previously undetected metabolic defect in the Complex II Caenorhabditis elegans mev-1 mutant strain using respiratory control analysis

Hypometabolism may play an important role in the pathogenesis of ageing and ageing-related diseases. The nematode Caenorhabditis elegans offers the opportunity to study "living mitochondria" in a small (~1 mm) animal replete with a highly stereotypical, yet complex, anatomy and physiology. Basal oxygen consumption rate is often employed as a proxy for energy metabolism in this context. This parameter is traditionally measured using single-chamber Clark electrodes without the addition of metabolic modulators. Recently, multi-well oxygen electrodes, facilitating addition of metabolic modulators and hence study of respiratory control during different mitochondrial respiration states, have been developed. However, only limited official protocols exist for C. elegans, and key limitations of these techniques are therefore unclear. Following modification and testing of some of the existing protocols, we used these methods to explore mitochondrial bioenergetics in live nematodes of an electron transfer chain Complex II mutant strain, mev-1, and identified a previously undetected metabolic defect. We find that mev-1 mutants cannot respond adequately to increased energy demands, suggesting that oxidative phosphorylation is more severely impaired in these animals than has previously been appreciated.

The Researchers' View of Scientific Rigor-Survey on the Conduct and Reporting of In Vivo Research

Reproducibility in animal research is alarmingly low, and a lack of scientific rigor has been proposed as a major cause. Systematic reviews found low reporting rates of measures against risks of bias (e.g., randomization, blinding), and a correlation between low reporting rates and overstated treatment effects. Reporting rates of measures against bias are thus used as a proxy measure for scientific rigor, and reporting guidelines (e.g., ARRIVE) have become a major weapon in the fight against risks of bias in animal research. Surprisingly, animal scientists have never been asked about their use of measures against risks of bias and how they report these in publications. Whether poor reporting reflects poor use of such measures, and whether reporting guidelines may effectively reduce risks of bias has therefore remained elusive. To address these questions, we asked in vivo researchers about their use and reporting of measures against risks of bias and examined how self-reports relate to reporting rates obtained through systematic reviews. An online survey was sent out to all registered in vivo researchers in Switzerland (N = 1891) and was complemented by personal interviews with five representative in vivo researchers to facilitate interpretation of the survey results. Return rate was 28% (N = 530), of which 302 participants (16%) returned fully completed questionnaires that were used for further analysis. According to the researchers' self-report, they use measures against risks of bias to a much greater extent than suggested by reporting rates obtained through systematic reviews. However, the researchers' self-reports are likely biased to some extent. Thus, although they claimed to be reporting measures against risks of bias at much lower rates than they claimed to be using these measures, the self-reported reporting rates were considerably higher than reporting rates found by systematic reviews. Furthermore, participants performed rather poorly when asked to choose effective over ineffective measures against six different biases. Our results further indicate that knowledge of the ARRIVE guidelines had a positive effect on scientific rigor. However, the ARRIVE guidelines were known by less than half of the participants (43.7%); and among those whose latest paper was published in a journal that had endorsed the ARRIVE guidelines, more than half (51%) had never heard of these guidelines. Our results suggest that whereas reporting rates may underestimate the true use of measures against risks of bias, self-reports may overestimate it. To a large extent, this discrepancy can be explained by the researchers' ignorance and lack of knowledge of risks of bias and measures to prevent them. Our analysis thus adds significant new evidence to the assessment of research integrity in animal research. Our findings further question the confidence that the authorities have in scientific rigor, which is taken for granted in the harm-benefit analyses on which approval of animal experiments is based. Furthermore, they suggest that better education on scientific integrity and good research practice is needed. However, they also question reliance on reporting rates as indicators of scientific rigor and highlight a need for more reliable predictors.

Energy crisis precedes global metabolic failure in a novel Caenorhabditis elegans Alzheimer Disease model

Alzheimer Disease (AD) is a progressive neurological disorder characterized by the deposition of amyloid beta (Aβ), predominantly the Aβ_1–42 form, in the brain. Mitochondrial dysfunction and impaired energy metabolism are important components of AD pathogenesis. However, the causal and temporal relationships between them and AD pathology remain unclear. Using a novel C. elegans AD strain with constitutive neuronal Aβ_1–42 expression that displays neuromuscular defects and age-dependent behavioural dysfunction reminiscent of AD, we have shown that mitochondrial bioenergetic deficit is an early event in AD pathogenesis, preceding dysfunction of mitochondrial electron transfer chain (ETC) complexes and the onset of global metabolic failure. These results are consistent with an emerging view that AD may be a metabolic neurodegenerative disease, and also confirm that Aβ-driven metabolic and mitochondrial effects can be reproduced in organisms separated by large evolutionary distances.

Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies

Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0–100% scale. Implantation of acellular biomaterials significantly improved cartilage regeneration by 15.6% compared to non-treated empty defect controls. The addition of biologics to biomaterials significantly improved cartilage regeneration by 7.6% compared to control biomaterials. No significant differences were found between biomaterials from natural or synthetic origin or between scaffolds, hydrogels and blends. No noticeable differences were found in outcome between animal models. The risk of bias assessment indicated poor reporting for the majority of studies, impeding an assessment of the actual risk of bias. In conclusion, implantation of biomaterials in osteochondral defects improves cartilage regeneration compared to natural healing, which is further improved by the incorporation of biologics.

Drug delivery systems for ovarian cancer treatment: a systematic review and meta-analysis of animal studies

Current ovarian cancer treatment involves chemotherapy that has serious limitations, such as rapid clearance, unfavorable biodistribution and severe side effects. To overcome these limitations, drug delivery systems (DDS) have been developed to encapsulate chemotherapeutics for delivery to tumor cells. However, no systematic assessment of the efficacy of chemotherapy by DDS compared to free chemotherapy (not in a DDS) has been performed for animal studies. Here, we assess the efficacy of chemotherapy in DDS on survival and tumor growth inhibition in animal studies. We searched PubMed and EMBASE (via OvidSP) to systematically identify studies evaluating chemotherapeutics encapsulated in DDS for ovarian cancer treatment in animal studies. Studies were assessed for quality and risk of bias. Study characteristics were collected and outcome data (survival/hazard ratio or tumor growth inhibition) were extracted and used for meta-analyses. Meta-analysis was performed to identify and explore which characteristics of DDS influenced treatment efficacy. A total of 44 studies were included after thorough literature screening (2,735 studies found after initial search). The risk of bias was difficult to assess, mainly because of incomplete reporting. A total of 17 studies (377 animals) and 16 studies (259 animals) could be included in the meta-analysis for survival and tumor growth inhibition, respectively. In the majority of the included studies chemotherapeutics entrapped in a DDS significantly improved efficacy over free chemotherapeutics regarding both survival and tumor growth inhibition. Subgroup analyses, however, revealed that cisplatin entrapped in a DDS did not result in additional tumor growth inhibition compared to free cisplatin, although it did result in improved survival. Micelles did not show a significant tumor growth inhibition compared to free chemotherapeutics, which indicates that micelles may not be a suitable DDS for ovarian cancer treatment. Other subgroup analyses, such as targeted versus non-targeted DDS or IV versus IP administration route, did not identify specific characteristics of DDS that affected treatment efficacy. This systematic review shows the potential, but also the limitations of chemotherapy by drug delivery systems for ovarian cancer treatment. For future animal research, we emphasize that data need to be reported with ample attention to detailed reporting.

A Systematic Review of Rhubarb (a Traditional Chinese Medicine) Used for the Treatment of Experimental Sepsis

Sepsis is a global major health problem in great need for more effective therapy. For thousands of years, Rhubarb had been used for various diseases including severe infection. Pharmacological studies and trials reported that Rhubarb may be effective in treating sepsis, but the efficacy and the quality of evidence remain unclear since there is no systematic review on Rhubarb for sepsis. The present study is the first systematic review of Rhubarb used for the treatment of experimental sepsis in both English and Chinese literatures by identifying 27 studies from 7 databases. It showed that Rhubarb might be effective in reducing injuries in gastrointestinal tract, lung, and liver induced by sepsis, and its potential mechanisms might include reducing oxidative stress and inflammation, ameliorating microcirculatory disturbance, and maintaining immune balance. Yet the positive findings should be interpreted with caution due to poor methodological quality. In a word, Rhubarb might be a promising candidate that is worth further clinical and experimental trials for sepsis therapy.

Caenorhabditis elegans: What We Can and Cannot Learn from Aging Worms

SIGNIFICANCE

The nematode Caenorhabditis elegans is a widely used model organism for research into aging. However, nematodes diverged from other animals between 600 and 1300 million years ago. Beyond the intuitive impression that some aspects of aging appear to be universal, is there evidence that insights into the aging process of nematodes may be applicable to humans?

RECENT ADVANCES

There have been a number of results in nematodes that appear to contradict long-held beliefs about mechanisms and causes of aging. For example, ablation of several key antioxidant systems has often failed to result in lifespan shortening in C. elegans.

CRITICAL ISSUES

While it is clear that some central signaling pathways controlling lifespan are broadly conserved across large evolutionary distances, it is less clear to what extent downstream molecular mechanisms of aging are conserved. In this review we discuss the biology of C. elegans and mammals in the context of aging and age-dependent diseases. We consider evidence from studies that attempt to investigate basic, possibly conserved mechanisms of aging especially in the context of the free radical theory of aging. Practical points, such as the need for blinding of lifespan studies and for appropriate biomarkers, are also considered.

FUTURE DIRECTIONS

As data on the aging process(es) in different organisms increase, it is becoming increasingly clear that there are both conserved (public) and private aspects to aging. It is important to explore the dividing lines between these two aspects and to be aware of the large gray areas in-between.

Evidence of Experimental Bias in the Life Sciences: Why We Need Blind Data Recording

Observer bias and other "experimenter effects" occur when researchers' expectations influence study outcome. These biases are strongest when researchers expect a particular result, are measuring subjective variables, and have an incentive to produce data that confirm predictions. To minimize bias, it is good practice to work "blind," meaning that experimenters are unaware of the identity or treatment group of their subjects while conducting research. Here, using text mining and a literature review, we find evidence that blind protocols are uncommon in the life sciences and that nonblind studies tend to report higher effect sizes and more significant p-values. We discuss methods to minimize bias and urge researchers, editors, and peer reviewers to keep blind protocols in mind.

Weight-bearing asymmetry and vertical activity differences in a rat model of post-traumatic knee osteoarthritis

OBJECTIVE

This study used a rat model of post-traumatic knee osteoarthritis (OA) created by anterior cruciate ligament transection with partial medial meniscectomy (ACLT + pMMx). In this model, mild to moderate structural changes that are typical of knee OA have been observed within 2 and 8 weeks post-surgery. We aimed to determine whether pain-related behaviours can distinguish between an ACLT + pMMx and a sham surgery group.

DESIGN

Three-month old male Sprague-Dawley rats underwent ACLT + pMMx on their right hindlimb within two groups of n = 6 each, and sham surgery within two groups of n = 5 each. Assessments evaluated percent ipsilateral weight-bearing for static weight-bearing and 18 different variables of exploratory motor behaviour at multiple time points between 1 and 8 weeks post-surgery. Histology was performed on the right hindlimbs at 4 and 8 weeks post-surgery.

RESULTS

Histology confirmed mild to moderate knee OA changes in the ACLT + pMMx group and the absence of knee OA changes in the sham group. Compared to the sham group, the ACLT + pMMx group had significantly lower percent ipsilateral weight-bearing from 1 through 8 weeks post-surgery. Compared to the sham group, the ACLT + pMMx group had significantly lower vertical activity (episode count, time, and count) values.

CONCLUSIONS

These findings suggest that ipsilateral weight-bearing deficit and vertical activity limitations resulted from the presence of knee OA-like changes in this model. When using the ACLT + pMMx-induced rat model of knee OA, percent ipsilateral weight-bearing and vertical activity distinguished between rats with and without knee OA changes. These variables may be useful outcome measures in preclinical research performed with this experimental post-traumatic knee OA model.