Pharmacological characterization of a novel putative nootropic beta-alanine derivative, MB-005, in adult zebrafish

BACKGROUND

Cognitive deficits represent an urgent biomedical problem, and are commonly reduced by nootropic drugs. Animal models, including both rodents and zebrafish, offer a valuable tool for studying cognitive phenotypes and screening novel nootropics. Beta-alanine and its derivatives have recently been proposed to exert nootropic activity.

AIMS

This study aimed to characterize putative nootropic profile of a novel β-alanine analogue, 1,3-diaminopropane (MB-005), in adult zebrafish.

METHODS

Nootropic profile of MB-005 was assessed in adult zebrafish in the novel tank and conditioned place aversion (CPA) tests acutely, and in cued-learning plus-maze (PMT) tests chronically.

RESULTS/OUTCOMES

MB-005 did not alter zebrafish anxiety-like behavior or monoamine neurochemistry acutely, improved short-term memory in the CPA test, but impaired cognitive performance in both CPA and PMT tests chronically.

CONCLUSIONS/INTERPRETATION

This study reveals high sensitivity of zebrafish cognitive phenotypes to MB-005, suggesting it as a potential novel cognitive enhancer acutely, but raises concerns over its cognitive (and, possibly, other) side-effects chronically.

Effect of uric acid in animal models of ischemic stroke: A systematic review and meta-analysis

Addition of uric acid (UA) to thrombolytic therapy, although safe, showed limited efficacy in improving patients' stroke outcome, despite alleged neuroprotective effects of UA in preclinical research. This systematic review assessed the effects of UA on brain structural and functional outcomes in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 16 and 14 eligible rodent studies for qualitative and quantitative synthesis, respectively. Range of evidence met 10 of a possible 13 STAIR criteria. Median (Q1, Q3) quality score was 7.5 (6, 10) on the CAMARADES 15-item checklist. For each outcome, we used standardised mean difference (SMD) as effect size and random-effects modelling. Meta-analysis showed that UA significantly reduced infarct size (SMD: -1.18; 95% CI [-1.47, -0.88]; p < 0.001), blood-brain barrier (BBB) impairment/oedema (SMD: -0.72; 95% CI [-0.97, -0.48]; p < 0.001) and neurofunctional deficit (SMD: -0.98; 95% CI [-1.32, -0.63]; p < 0.001). Overall, there was low to moderate between-study heterogeneity and sizeable publication bias. In conclusion, published rodent data suggest that UA improves outcome following ischemic stroke by reducing infarct size, improving BBB integrity and ameliorating neurofunctional condition. Specific recommendations are given for further high-quality preclinical research required to better inform clinical research.

The Conditions Under Which Piracetam Is Used and the Factors That Can Improve National Institute of Health Stroke Scale Score in Ischemic Stroke Patients and the Importance of Previously Unnoticed Factors From a Hospital-Based Observational Study in Taiwan

This study aimed to explore the associations of piracetam use and the clinical characteristics of NIHSS (National Institute of Health Stroke Scale) changes-the importance of which, as prognosis related factors, was previously unnoticed-and analyze the associations of piracetem with NIHSS changes by stratifying clinical characteristics. This observational retrospective study was conducted by enrolling patients based on 2483 stroke registration data cohorts from a 1200-bed regional Tungs' Taichung MetroHarbor Hospital, located in central Taiwan from 1 January 1 2011 to 31 December 2015. Patients were excluded if they had intravenous a thrombolytic agent within 3 hours of symptoms onset (n = 49), incomplete or erroneous NIHSS scores (n = 953), or transient ischemia stroke (n = 130). Logistic regression model was applied for associating piracetam treatment and clinical characteristics with NIHSS score changes between admission and discharge, and subgroup analysis to assess the conditions under which piracetam can be used. Multivariate analysis revealed NIHSS scores improvement in atrial fibrillation, large-artery atherosclerosis, underweight, current smoker, ex-smoker, and piracetam. Subgroup analysis showed piracetam is beneficial in the following: age ≥75 years olds, males, those of normal weight, those who are obese, ex-smokers, those with hypertension, dyslipidemia, those without diabetes mellitus, nor atrial fibrillation. The selection of the conditions under which piracetam treatment should be given, and clinical characteristics, is important for NIHSS improvement of ischemic stroke patients in Taiwan.

Piracetam for Aphasia in Post-stroke Patients: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Aphasia is a common symptom in post-stroke patients. Piracetam is a commonly used nootropic agent that promises various benefits to brain function, including language improvement.

OBJECTIVE

We performed a systematic review and meta-analysis to assess whether piracetam facilitates the rehabilitation of language performance in post-stroke patients.

METHODS

Randomized controlled trials (RCTs) of piracetam treatment in post-stroke patients published in any language were included, excluding those involving pre-existing cognitive disorders such as dementia and mood disturbances. We searched several databases including PubMed, EMBASE, Cochrane Central, CINAHL, Web of Science, and PsycINFO for RCTs published up to 31 December 2015. We conducted a meta-analysis using RevMan (version 5.3), with standardized mean differences (SMDs) and fixed-effect models, and used StataSE (version 13) for the detection of publication bias. This study has been submitted to PROSPERO, and its registration number is CRD42016034088.

RESULTS

We identified 1180 titles and abstracts, and finally included seven RCTs in this meta-analysis. The number of participants in each study ranged from 19 to 66, summing up to 261 patients overall. The dose of piracetam was consistent while the frequency and time of therapy varied. The assessment of the language at the end of trials showed no significant improvement in overall severity of aphasia [SMD 0.23, 95 % confidence interval (CI) -0.03 to 0.49, P = 0.08], but written language (SMD 0.35, 95 % CI 0.04 to 0.66, P = 0.03) showed pronounced improvement. Subgroup analyses indicated a dissociation of effectiveness between short- and long-term assessment in overall severity (P = 0.008, I (2) = 85.6 %) in terms of tests for subgroup differences, and a mild trend toward dissociation in written subtests (P = 0.30, I (2) = 5.1 %). Funnel plots and Egger's test identified no obvious publication bias in the primary variable.

CONCLUSIONS

Piracetam plays a limited role in the rehabilitation of overall language impairment and only benefits written language ability at the end of trials. Its effect on overall linguistic level and written language tends to emerge within a short period and declines thereafter.

Critical appraisal of studies using laboratory animal models

In this manuscript we discuss an approach to critically appraising papers based on the results of laboratory animal experiments. The roles of external and internal validity in critically appraising the results of a paper are introduced. The risk of bias domains used by the Cochrane Handbook of Systematic Reviews of Interventions form the basis for assessing internal validity. The bias domains discussed include the selection bias, performance bias, outcome assessment bias, attrition bias, and reporting bias. Further, an approach to considering the role of chance in research findings is discussed.

Late, never or non-existent: the inaccessibility of preclinical evidence for new drugs

BACKGROUND AND PURPOSE

Animal studies establish much of the evidence used to support clinical development of new drugs. Recent studies suggest that many preclinical investigations are withheld from publication, leading to exaggerated estimates of clinical utility. We sought to estimate the volume and properties of all published animal efficacy studies for a cohort of novel drugs.

EXPERIMENTAL APPROACH

We searched biomedical databases to identify 47 novel drugs whose first trials were reported between 2000 and 2003, inclusive. Next, we searched for all published animal studies testing the same drug, regardless of publication date. We then extracted items from titles and abstracts of eligible studies.

KEY RESULTS

We identified 2462 efficacy studies, representing an average of 52 studies per drug. No published efficacy studies were available for three drugs in our sample. The volume of efficacy studies was related to how far the drug had progressed in clinical development (Spearman's correlation coefficient = 0.66, P < 0.0001). Most (87%) accessible animal efficacy studies were reported after publication of the first trial, and for 17% of the drugs in our sample, no efficacy studies were published before the first trial report. Disease indications used in trials often did not match those modelled in efficacy studies; for 35% of indications tested in trials, we were unable to identify any published efficacy studies in models of the same indication.

CONCLUSIONS AND IMPLICATIONS

The volume of published efficacy studies is large, although numerous gaps reflect non-publication, publication delay or non-performance of efficacy studies supporting trials.

The need for randomization in animal trials: an overview of systematic reviews

Background and Objectives

Randomization, allocation concealment, and blind outcome assessment have been shown to reduce bias in human studies. Authors from the Collaborative Approach to Meta Analysis and Review of Animal Data from Experimental Studies (CAMARADES) collaboration recently found that these features protect against bias in animal stroke studies. We extended the scope the work from CAMARADES to include investigations of treatments for any condition.

Methods

We conducted an overview of systematic reviews. We searched Medline and Embase for systematic reviews of animal studies testing any intervention (against any control) and we included any disease area and outcome. We included reviews comparing randomized versus not randomized (but otherwise controlled), concealed versus unconcealed treatment allocation, or blinded versus unblinded outcome assessment.

Results

Thirty-one systematic reviews met our inclusion criteria: 20 investigated treatments for experimental stroke, 4 reviews investigated treatments for spinal cord diseases, while 1 review each investigated treatments for bone cancer, intracerebral hemorrhage, glioma, multiple sclerosis, Parkinson's disease, and treatments used in emergency medicine. In our sample 29% of studies reported randomization, 15% of studies reported allocation concealment, and 35% of studies reported blinded outcome assessment. We pooled the results in a meta-analysis, and in our primary analysis found that failure to randomize significantly increased effect sizes, whereas allocation concealment and blinding did not. In our secondary analyses we found that randomization, allocation concealment, and blinding reduced effect sizes, especially where outcomes were subjective.

Conclusions

Our study demonstrates the need for randomization, allocation concealment, and blind outcome assessment in animal research across a wide range of outcomes and disease areas. Since human studies are often justified based on results from animal studies, our results suggest that unduly biased animal studies should not be allowed to constitute part of the rationale for human trials.

A call for transparent reporting to optimize the predictive value of preclinical research

The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress.

Exploring the efficacy of constraint in animal models of stroke: meta-analysis and systematic review of the current evidence

BACKGROUND

Constraint-induced movement therapy (CIMT) is used to counteract learned nonuse observed following stroke in humans and has been shown to improve function. Variations of CIMT used in animal models of stroke have the potential to inform and improve our understanding of this intervention.

OBJECTIVE

To conduct a systematic review of studies investigating constraint in experimental stroke. The authors aimed to assess the quality and establish the efficacy of constraint on neurobehavior, cognitive function, infarct size, and stress and mortality and to determine the optimal dose or time to administration.

METHODS

Systematic review with meta-analysis was used. Data were analyzed using DerSimonian and Laird weighted-mean-difference random effects meta-analysis.

RESULTS

The quality scores of the 8 articles (15 studies) included were moderate (median 5/10; interquartile range, 4.8-6.0). There was a trend for animals with constraint to have worse neurobehavioral scores (-10% worse; 95% confidence interval [CI] = -20 to 0; P = .06). Infarct volumes were not significantly different between groups (-3% larger with constraint; 95% CI = -15 to 9; P = .63). Cognitive function was significantly better after constraint, although this estimate was based on only 28 animals from 2 studies. Insufficient data prevented analysis of the effect of constraint on stress and mortality.

CONCLUSIONS

This meta-analysis showed no benefit of constraint on neurobehavioral scores, which is at odds with some human studies. Animal models may help us efficiently explore the biological basis of rehabilitation interventions; however, review of the data in this study raise uncertainty about its effectiveness in humans.

Does long term use of piracetam improve speech disturbances due to ischemic cerebrovascular diseases?

Aphasia causes significant disability and handicap among stroke survivors. Language therapy is recommended for aphasic patients, but not always available. Piracetam, an old drug with novel properties, has been shown to have mild beneficial effects on post-stroke aphasia. In the current study, we investigated the effects of 6 months treatment with piracetam on aphasia following stroke. Thirty patients with first-ever ischemic strokes and related aphasia were enrolled in the study. The scores for the National Institutes of Health Stroke Scale (NIHSS), Barthel Index (BI), modified Rankin Scale (mRS), and Gülhane Aphasia Test were recorded. The patients were scheduled randomly to receive either 4.8 g piracetam daily or placebo treatment for 6 months. At the end of 24 weeks, clinical assessments and aphasia tests were repeated. The level of improvement in the clinical parameters and aphasia scores was compared between the two groups. All patients had large lesions and severe aphasia. No significant difference was observed between the piracetam and placebo groups regarding the improvements in the NIHSS, BI and mRS scores at the end of the treatment. The improvements observed in spontaneous speech, reading fluency, auditory comprehension, reading comprehension, repetition, and naming were not significantly different in the piracetam and placebo groups, the difference reached significance only for auditory comprehension in favor of piracetam at the end of the treatment. Piracetam is well-tolerated in patients with post-stroke aphasia. Piracetam taken orally in a daily dose of 4.8 g for 6 months has no clear beneficial effect on post-stroke language disorders.

Hyperglycaemia and infarct size in animal models of middle cerebral artery occlusion: systematic review and meta-analysis

Poststroke hyperglycaemia (PSH) is common, has an unclear pathophysiology, and is associated with poor outcomes. Animal studies report conflicting findings. We systematically reviewed the effects of hyperglycaemia on infarct volume in middle cerebral artery occlusion (MCAO) models, generating weighted mean differences between groups using random effects models summarised as effect size (normalised to control group infarct volume as 100%) and 95% confidence interval. Of 72 relevant papers, 23 reported infarct volume. Studies involved 664 animals and 35 distinct comparisons. Hyperglycaemia was induced by either streptozotocin (STZ, 17 comparisons, n=303) or dextrose (18 comparisons, n=356). Hyperglycaemic animals had infarcts that were 94% larger, but STZ was associated with significantly greater increase in infarct volumes than dextrose infusion (140% larger versus 48% larger). In seven studies, insulin did not significantly reduce infarct size and results were heterogeneous. Although hyperglycaemia exacerbates infarct volume in MCAO models, studies are heterogeneous, and do not address the common clinical problem of PSH because they have used either the STZ model of type I diabetes or extremely high glucose loads. Insulin had a nonsignificant and significantly heterogeneous effect. Further studies with relevant models may inform clinical trial design.

An enriched environment improves sensorimotor function post-ischemic stroke

OBJECTIVE

An enriched environment (EE) refers to conditions that facilitate or enhance sensory, cognitive, motor, and social stimulation relative to standard (laboratory) conditions. Despite numerous published studies investigating this concept in animal stroke models, there is still debate around its efficacy. The authors performed a systematic review and meta-analysis to determine the efficacy of an EE on neurobehavioral scores, learning, infarct size, and mortality in animal models of ischemic stroke.

METHODS

Systematic review of controlled studies of the use of an EE in experimental stroke was conducted. Data extracted were analyzed using weighted mean difference meta-analysis. For pooled tests of neurobehavioral scores, a random effects standardized method was used.

RESULTS

Animals recovering in an EE poststroke had mean neurobehavioral scores 0.9 standard deviations (95% confidence interval [CI] = 0.5-1.3; P < .001) above the mean scores of animals recovering in standard conditions and showed a trend toward improvement in learning (25.1% improvement; 95% CI = 3.7-46.6; P = .02). There was no significant increase in death. Animals exposed to an EE had 8.0% larger infarcts than control animals (95% CI = 1.8-14.1; P = .015).

CONCLUSIONS

The results indicate significant improvements in sensorimotor function with EE poststroke but suggest a small increase in infarct volume. Clarification of the underlying mechanisms requires further study but should not overshadow the observed functional improvements and their application to clinical trials during stroke rehabilitation.

Publication bias in reports of animal stroke studies leads to major overstatement of efficacy

The consolidation of scientific knowledge proceeds through the interpretation and then distillation of data presented in research reports, first in review articles and then in textbooks and undergraduate courses, until truths become accepted as such both amongst "experts" and in the public understanding. Where data are collected but remain unpublished, they cannot contribute to this distillation of knowledge. If these unpublished data differ substantially from published work, conclusions may not reflect adequately the underlying biological effects being described. The existence and any impact of such "publication bias" in the laboratory sciences have not been described. Using the CAMARADES (Collaborative Approach to Meta-analysis and Review of Animal Data in Experimental Studies) database we identified 16 systematic reviews of interventions tested in animal studies of acute ischaemic stroke involving 525 unique publications. Only ten publications (2%) reported no significant effects on infarct volume and only six (1.2%) did not report at least one significant finding. Egger regression and trim-and-fill analysis suggested that publication bias was highly prevalent (present in the literature for 16 and ten interventions, respectively) in animal studies modelling stroke. Trim-and-fill analysis suggested that publication bias might account for around one-third of the efficacy reported in systematic reviews, with reported efficacy falling from 31.3% to 23.8% after adjustment for publication bias. We estimate that a further 214 experiments (in addition to the 1,359 identified through rigorous systematic review; non publication rate 14%) have been conducted but not reported. It is probable that publication bias has an important impact in other animal disease models, and more broadly in the life sciences.

What is the translational efficacy of chemotherapeutic drug research in neuro-oncology? A systematic review and meta-analysis of the efficacy of BCNU and CCNU in animal models of glioma

INTRODUCTION

The translational value of experimental therapeutic neuroscience research to clinical practice is highly variable. This has been particularly well demonstrated in the field of neuroprotective agents following either head injury or stroke. In this study we evaluate the efficacy of systemic BCNU and CCNU in experimental glioma models and how the experimental data has translated into clinical practice.

METHODS

A systematic review of the efficacy of BCNU and CCNU, against experimental rodent and murine in vivo glioma models was conducted. Selected articles were graded on a 15 point scale for scientific methodology. A stratified meta-analysis based on median-survival data and effect sizes was performed to generate global-efficacy estimates for BCNU and CCNU, and to produce 'weighted-mean effect-sizes' for individual sub-categories of selected study-characteristics.

RESULTS

Fourteen papers satisfied search criteria and encompassed 231 treatment comparisons in 2256 animals. The median methodology score was 9 (range 7-12/15). Global-efficacy estimates were BCNU 0.194 (95% CI -0.538 to 0.927) and CCNU 0.432 (95% CI -0.392 to 1.256), with CCNU being significantly more effective than BCNU. Because of these wide confidence intervals a beneficial or detrimental effect of either agent could not be confirmed. Most selected study-design characteristics (e.g. glioma cell line, drug dosage, drug scheduling, mode of drug administration, timing of therapy after glioma implantation but not animal used) significantly influenced the efficacy-results obtained. The methodological score did not influence efficacy-estimate.

CONCLUSION

This review has found (i) experimental-design influenced the efficacy-data obtained and (ii) that there is highly variable outcome data for the efficacy of both BCNU and CCNU in experimental in vivo rodent and murine glioma models. In many ways these findings are analagous to the use of nitrosoureas in human malignant glioma. The statistically significant small beneficial effect of nitrosoureas in combination with other chemotherapeutic agents in human glioma was only noted after a meta-analysis of human randomized controlled trials.