Resolving the Tension Between Exploration and Confirmation in Preclinical Biomedical Research

Longer Periods of Hypothermia Provide Greater Protection Against Focal Ischemia: A Systematic Review of Animal Studies Manipulating Treatment Duration

Decades of animal research show therapeutic hypothermia (TH) to be potently neuroprotective after cerebral ischemic injuries. While there have been some translational successes, clinical efficacy after ischemic stroke is unclear. One potential reason for translational failures could be insufficient optimization of dosing parameters. In this study, we conducted a systematic review of the PubMed database to identify all preclinical controlled studies that compared multiple TH durations following focal ischemia, with treatment beginning at least 1 hour after ischemic onset. Six studies met our inclusion criteria. In these six studies, six of seven experiments demonstrated an increase in cerebroprotection at the longest duration tested. The average effect size (mean Cohen's d ± 95% confidence interval) at the shortest and longest durations was 0.4 ± 0.3 and 1.9 ± 1.1, respectively. At the longest durations, this corresponded to percent infarct volume reductions between 31.2% and 83.9%. Our analysis counters previous meta-analytic findings that there is no relationship, or an inverse relationship between TH duration and effect size. However, underreporting often led to high or unclear risks of bias for each study as gauged by the SYRCLE Risk of Bias tool. We also found a lack of investigations of the interactions between duration and other treatment considerations (e.g., method, delay, and ischemic severity). With consideration of methodological limitations, an understanding of the relationships between treatment parameters is necessary to determine proper "dosage" of TH, and should be further studied, considering clinical failures that contrast with strong cerebroprotective results in most animal studies.

An Assessment of Physical and N6-Cyclohexyladenosine-Induced Hypothermia in Rodent Distal Focal Ischemic Stroke

Therapeutic hypothermia (TH) mitigates damage in ischemic stroke models. However, safer and easier TH methods (e.g., pharmacological) are needed to circumvent physical cooling complications. This study evaluated systemic and pharmacologically induced TH using the adenosine A1 receptor agonist, N6-cyclohexyladenosine (CHA), with control groups in male Sprague-Dawley rats. CHA was administered intraperitoneally 10 minutes following a 2-hour intraluminal middle cerebral artery occlusion. We used a 1.5 mg/kg induction dose, followed by three 1.0 mg/kg doses every 6 hours for a total of 4 doses, causing 20-24 hours of hypothermia. Animals assigned to physical hypothermia and CHA-hypothermia had similar induction rates and nadir temperatures, but forced cooling lasted ∼6 hours longer compared with CHA-treated animals. The divergence is likely attributable to individual differences in CHA metabolism, which led to varied durations at nadir, whereas physical hypothermia was better regulated. Physical hypothermia significantly reduced infarction (primary endpoint) on day 7 (mean reduction of 36.8 mm3 or 39% reduction; p = 0.021 vs. normothermic animals; Cohen's d = 0.75), whereas CHA-induced hypothermia did not (p = 0.33). Similarly, physical cooling improved neurological function (physical hypothermia median = 0, physical normothermia median = 2; p = 0.008) and CHA-induced cooling did not (p > 0.99). Our findings demonstrate that forced cooling was neuroprotective compared with controls, but prolonged CHA-induced cooling was not neuroprotective.

Challenges in Translating Regenerative Therapies for Spinal Cord Injury

Regenerating the injured spinal cord is a substantial challenge with many obstacles that need to be overcome to achieve robust functional benefits. This abundance of hurdles can partly explain the limited success when applying regenerative intervention treatments in animal models and/or people. In this article, we elaborate on a few of these obstacles, starting with the applicability of animal models and how they compare to the clinical setting. We then discuss the requirement for combinatorial interventions and the associated problems in experimental design, including the addition of rehabilitative training. The article expands on differences in lesion sizes and locations between humans and common animal models, and how this difference can determine the success or failure of an intervention. An additional and frequently overlooked problem in the translation of interventions that applies beyond the field of neuroregeneration is the reporting bias and the lack of transparency in reporting findings. New data mandates are tackling this problem and will eventually result in a more balanced view of the field. Finally, we will discuss strategies to negotiate the challenging course of successful translation to facilitate successful translation of regeneration promoting interventions.

A systematic review and meta-analysis on the efficacy of glibenclamide in animal models of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating stroke with many mechanisms of injury. Edema worsens outcome and can lead to mortality after ICH. Glibenclamide (GLC), a sulfonylurea 1- transient receptor potential melastatin 4 (Sur1-Trpm4) channel blocker, has been shown to attenuate edema in ischemic stroke models, raising the possibility of benefit in ICH. This meta-analysis synthesizes current pre-clinical (rodent) literature regarding the efficacy of post-ICH GLC administration (vs. vehicle controls) on behaviour (i.e., neurological deficit, motor, and memory outcomes), edema, hematoma volume, and injury volume. Six studies (5 in rats and 1 in mice) were included in our meta-analysis (PROSPERO registration = CRD42021283614). GLC significantly improved behaviour (standardized mean difference (SMD) = -0.63, [-1.16, -0.09], n = 70-74) and reduced edema (SMD = -0.91, [-1.64, -0.18], n = 70), but did not affect hematoma volume (SMD = 0.0788, [-0.5631, 0.7207], n = 18-20), or injury volume (SMD = 0.2892, [-0.4950, 1.0734], n = 24). However, these results should be interpreted cautiously. Findings were conflicted with 2 negative and 4 positive reports, and Egger regressions indicated missing negative edema data (p = 0.0001), and possible missing negative behavioural data (p = 0.0766). Experimental quality assessed via the SYRCLE and CAMARADES checklists was concerning, as most studies demonstrated high risks of bias. Studies were generally low-powered (e.g., average n = 14.4 for behaviour), and future studies should employ sample sizes of 41 to detect our observed effect size in behaviour and 33 to detect our observed effect in edema. Overall, missing negative studies, low study quality, high risk of bias, and incomplete attention to key recommendations (e.g., investigating female, aged, and co-morbid animals) suggest that further high-powered confirmatory studies are needed before conclusive statements about GLC's efficacy in ICH can be made, and before further clinical trials are performed.

Digital content marketing consumption motives in the age of social media: an investigation of relational and monetary outcomes

Purpose

Although digital content marketing (DCM) research and industry-wide expenditure is growing very rapidly owing to the positive outcomes associated with this new pull marketing strategy, research has not completely mapped how DCM activities can be optimized in the social media brand community context. This paper seeks to understand how social media DCM activities can be optimized to achieve greater relational and monetary outcomes for different products.

Design/methodology/approach

A structural equation modeling procedure was used to analyze 416 survey responses obtained from members of Facebook brand communities in South Africa.

Findings

The results reveal that social media DCM consumption motives exert significant differential effects on both relational and monetary marketing outcomes in search and experience product contexts while also demonstrating the mechanism through which social media DCM consumption motives lead to contributing social media engagement behaviors.

Practical implications

The study findings call for the need for firms to understand the motives that drive the consumption of DCM in social media brand communities. Specifically, marketers of search products should deploy more of hedonic contents such as images while simultaneously keeping highly textual DCM to a minimum in Facebook brand communities as this works better for experience products. Finally, more authentic SM-DCM activities that effectively address the authenticity SM-DCM consumption motive can result from the DCM activities of social media opinion leaders and genuine consumer–brand interactions in the context of Facebook brand communities.

Originality/value

This paper broke new grounds in three unique directions in terms of: (1) the relative salience of SM-DCM consumption motives in enhancing WTP and different aspects of SMBE; (2) the contextual influence of product type on SM-DCM activities optimization and (3) the mechanisms that underlie the effects of SM-DCM consumption motives on contributing SMBE in the Facebook brand community context.

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.

A critical analysis of research methods and experimental models to study dentinal microcracks

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

Robust preclinical evidence in somatic cell genome editing: A key driver of responsible and efficient therapeutic innovations

Somatic cell genome editing (SCGE) is highly promising for therapeutic innovation. This study demonstrates that the majority of 46 preclinical SCGE studies discussed in reviews as particularly promising for clinical translation do not report on key elements for robust and confirmatory research practices: randomization, blinding, sample size calculation, data handling, pre-registration, multi-centric study design, and independent confirmation. We present the here-examined reporting standards and the new National Institutes of Health (NIH) funding criteria for SCGE research as a viable solution to protect this promising field from backlashes. We argue that the implementation of the novel methodological standards provides the opportunity for SCGE research to become a lighthouse example for trustworthy and useful translational research.

Glibenclamide does not improve outcome following severe collagenase-induced intracerebral hemorrhage in rats

Intracerebral hemorrhage (ICH) is a devastating insult with few effective treatments. Edema and raised intracranial pressure contribute to poor outcome after ICH. Glibenclamide blocks the sulfonylurea 1 transient receptor potential melastatin 4 (Sur1-Trpm4) channel implicated in edema formation. While glibenclamide has been found to improve outcome and reduce mortality in animal models of severe ischemic stroke, in ICH the effects are less clear. In our previous study, we found no benefit after a moderate-sized bleed, while others have reported benefit. Here we tested the hypothesis that glibenclamide may only be effective in severe ICH, where edema is an important contributor to outcome. Glibenclamide (10 μg/kg loading dose, 200 ng/h continuous infusion) was administered 2 hours post-ICH induced by collagenase injection into the striatum of adult rats. A survival period of 24 hours was maintained for experiments 1-3, and 72 hours for experiment 4. Glibenclamide did not affect hematoma volume (~81 μL) or other safety endpoints (e.g., glucose levels), suggesting the drug is safe. However, glibenclamide did not lessen striatal edema (~83% brain water content), ionic dyshomeostasis (Na+, K+), or functional impairment (e.g., neurological deficits (median = 10 out of 14), etc.) at 24 hours. It also did not affect edema at 72 h (~86% brain water content), or overall mortality rates (25% and 29.4% overall in vehicle vs. glibenclamide-treated severe strokes). Furthermore, glibenclamide appears to worsen cytotoxic edema in the peri-hematoma region (cell bodies were 46% larger at 24 h, p = 0.0017), but no effect on cell volume or density was noted elsewhere. Overall, these findings refute our hypothesis, as glibenclamide produced no favorable effects following severe ICH.

Are randomized controlled trials in urology being conducted with justification?

CONTEXT

Considering the substantial increase in research funding in the field of urology, minimizing research waste should be a top priority. Systematic reviews (SRs) compile available evidence regarding a clinical question into a single critical resource. If properly utilized, SRs can help minimize redundant studies, focus attention to unsubstantiated treatments, and reduce research waste.

OBJECTIVES

To appraise the use of SRs as justification for conducting randomized controlled trials (RCTs) published in high impact urology journals, and to report the ways SRs were incorporated into RCT manuscripts published in the top four urology journals by h5 index.

METHODS

On December 13, 2019, a PubMed search was conducted for RCTs published in the top four urology journals according to the Google Scholar h5-index: European Urology, BJU International, The Journal of Urology, and Urology. For an article to be eligible for inclusion in this study, it must have been a full length RCT, published between November 30, 2014, and November 30, 2019 in one of the identified journals, reported only human subjects, and been accessible in English. The following data points were extracted independently by select investigators from each included RCT: manuscript title, year of publication, journal title, type of intervention (drug, medical device, procedure, other), funding source (government, hospital/university, industry, mixed) type of trial (parallel groups, crossover, cluster), and total number of participants reported in each RCT. The included RCTs were searched for reference to an SR, which was then recorded as "yes - verbatim," "yes - inferred," or "not used as justification" and the location in the manuscript where the SR was cited was recorded.

RESULTS

Of the 566 articles retrieved, 276 were included. Overall, 150 (54.3%) RCTs cited an SR as either verbatim (108; 39.1%) or inferred (42; 15.2%) trial justification, while 126 (45.7%) did not use an SR for RCT justification. Of those 126, 107 (84.9%) RCTs did not cite an SR to any extent. A significant association was noted between verbatim justification and type of intervention (x ²=20.23, p=0.017), with 18 of 31 (58.1%) "other" interventions (i.e. psychosocial intervention, exercise programs, and online therapy) having an SR cited as verbatim justification. Only 39 of 118 (33.1%) pharmaceutical trials referenced an SR as verbatim justification. Of 403 systematic review citations, 205 (50.8%) appeared in the Discussion section, while 15 (3.7%) were in the Methods section.

CONCLUSIONS

We found that RCTs published in four high impact urology journals inconsistently referenced an SR as justification and 39.1% of our entire sample did not reference an SR at all. These findings indicate that a divide exists between the instruction and implementation of evidence based medicine in the field of urology concerning RCTs published in the top four journals. Educating clinicians and researchers on the use of SR as justification for RCTs in urology may reduce research waste and increase the quality of RCTs in the field.

An update to the Monro-Kellie doctrine to reflect tissue compliance after severe ischemic and hemorrhagic stroke

High intracranial pressure (ICP) can impede cerebral blood flow resulting in secondary injury or death following severe stroke. Compensatory mechanisms include reduced cerebral blood and cerebrospinal fluid volumes, but these often fail to prevent raised ICP. Serendipitous observations in intracerebral hemorrhage (ICH) suggest that neurons far removed from a hematoma may shrink as an ICP compliance mechanism. Here, we sought to critically test this observation. We tracked the timing of distal tissue shrinkage (e.g. CA1) after collagenase-induced striatal ICH in rat; cell volume and density alterations (42% volume reduction, 34% density increase; p < 0.0001) were highest day one post-stroke, and rebounded over a week across brain regions. Similar effects were seen in the filament model of middle cerebral artery occlusion (22% volume reduction, 22% density increase; p ≤ 0.007), but not with the Vannucci-Rice model of hypoxic-ischemic encephalopathy (2.5% volume increase, 14% density increase; p ≥ 0.05). Concerningly, this 'tissue compliance' appears to cause sub-lethal damage, as revealed by electron microscopy after ICH. Our data challenge the long-held assumption that 'healthy' brain tissue outside the injured area maintains its volume. Given the magnitude of these effects, we posit that 'tissue compliance' is an important mechanism invoked after severe strokes.

Translational Intracerebral Hemorrhage Research: Has Current Neuroprotection Research ARRIVEd at a Standard for Experimental Design and Reporting?

One major aim of preclinical intracerebral hemorrhage (ICH) research is to develop and test potential neuroprotectants. Published guidelines for experimental design and reporting stress the importance of clearly and completely reporting results and methodological details to ensure reproducibility and maximize information availability. The current review has two objectives: first, to characterize current ICH neuroprotection research and, second, to analyze aspects of translational design in preclinical ICH studies. Translational design is the adoption and reporting of experimental design characteristics that are thought to be clinically relevant and critical to reproducibility in animal studies (e.g., conducting and reporting experiments according to the STAIR and ARRIVE guidelines, respectively). Given that ICH has no current neuroprotective treatments and an ongoing reproducibility crisis in preclinical research, translational design should be considered by investigators. We conducted a systematic review of ICH research from 2015 to 2019 using the PubMed database. Our search returned 281 published manuscripts studying putative neuroprotectants in animal models. Contemporary ICH research predominantly uses young, healthy male rodents. The collagenase model is the most commonly used. Reporting of group sizes, blinding, and randomization are almost unanimous, but group size calculations, mortality and exclusion criteria, and animal model characteristics are infrequently reported. Overall, current ICH neuroprotection research somewhat aligns with experimental design and reporting guidelines. However, there are areas for improvement. Because failure to consider translational design is associated with inflation of effect sizes (and possibly hindered reproducibility), we suggest that researchers, editors, and publishers collaboratively consider enhanced adherence to published guidelines.

Framework for advancing rigorous research

There is a pressing need to increase the rigor of research in the life and biomedical sciences. To address this issue, we propose that communities of 'rigor champions' be established to campaign for reforms of the research culture that has led to shortcomings in rigor. These communities of rigor champions would also assist in the development and adoption of a comprehensive educational platform that would teach the principles of rigorous science to researchers at all career stages.