ORCID Profile
0000-0002-2512-7724
Current Organisation
University of Tasmania
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Publisher: SAGE Publications
Date: 13-01-2010
Abstract: Animal models of ischemic stroke often neglect comorbidities common in patients. This study shows the feasibility of inducing stroke by 2 h of thread occlusion of the middle cerebral artery in aged (56 week old) spontaneously hypertensive rats (SHRs) with both acute (2 weeks) and chronic (36 weeks) diabetes. After modifying the streptozotocin dosing regimen to ensure that old SHRs survived the induction of diabetes, few died after induction of stroke. Induction of stroke is feasible in rats with multiple comorbidities. Inclusion of such comorbid animals may improve translation from the research laboratory to the clinic.
Publisher: Cold Spring Harbor Laboratory
Date: 15-07-2019
DOI: 10.1101/703181
Abstract: Reproducible science requires transparent reporting. The ARRIVE guidelines were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here we introduce ARRIVE 2019. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise the items and split the guidelines into two sets, the ARRIVE Essential 10, which constitute the minimum requirement, and the Recommended Set, which describes the research context. This ision facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers to verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document that serves 1) to explain the rationale behind each item in the guidelines, 2) to clarify key concepts and 3) to provide illustrative ex les. We aim through these changes to help ensure that researchers, reviewers and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.JNEUMETH.2013.09.010
Abstract: Meta-analyses of data from human studies are invaluable resources in the life sciences and the methods to conduct these are well documented. Similarly there are a number of benefits in conducting meta-analyses on data from animal studies they can be used to inform clinical trial design, or to try and explain discrepancies between preclinical and clinical trial results. However there are inherit differences between animal and human studies and so applying the same techniques for the meta-analysis of preclinical data is not straightforward. For ex le preclinical studies are frequently small and there is often substantial heterogeneity between studies. This may have an impact on both the method of calculating an effect size and the method of pooling data. Here we describe a practical guide for the meta-analysis of data from animal studies including methods used to explore sources of heterogeneity.
Publisher: Georg Thieme Verlag KG
Date: 2015
DOI: 10.1160/TH14-11-0967
Abstract: P2Y12 receptor is required for sustained activation of integrin αllbβ3, irreversible platelet aggregation and thrombus stabilisation. Tetraspanin superfamily member CD151 associates with integrin aNbp3 and plays critical roles in regulation of thrombus growth and stability in vivo. The possible functional relationship between P2Y12 and CD151 in a molecular cluster in platelets may affect thrombus formation. Hence our aim was to investigate the physical and functional requirements for this association in platelets. Our investigations reveal a specific and constitutive association between CD151 and P2Y12 receptor in human platelets shown by immunoprecipitation/western blot studies and by flow cytometry. Specifically, the prominent association involves CD151 with P2Y12 oligomers, and to a lesser extent P2Y12 monomers. This association is not altered by platelet aggregation induced by different agonists. There is also a distinct complex of tetraspanin CD151 with ADP purinergic receptor P2Y12 but not P2Y1. P2Y12 oligomer interaction with CD151 is selective as compared to other tetraspanins. To investigate the functional relationship between these receptors in platelets we used wild-type or CD151 knockout (KO) mice treated with either PBS or 50 mg/kg clopidogrel. CD151 KO mice treated with clopidogrel exhibited synergy in delayed kinetics of clot retraction, in PAR-4 and collagen-mediated platelet aggregation, platelet spreading on fibrinogen and without restricting cAMP inhibition. Clopidogrel treated CD151 KO arterioles showed smaller and less stable thrombi with increased tendency to embolise ex vivo and in vivo. These studies demonstrate a complementary role between CD151 and P2Y12 receptor in platelets in regulating thrombus growth and stability.
Publisher: Elsevier BV
Date: 10-1999
Publisher: Elsevier BV
Date: 11-2000
Publisher: Frontiers Media SA
Date: 14-06-2016
Publisher: eLife Sciences Publications, Ltd
Date: 08-09-2017
DOI: 10.7554/ELIFE.24260
Abstract: Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, s le size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small s le size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a s le size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2004
DOI: 10.1161/01.STR.0000125719.25853.20
Abstract: Background and Purpose— The extensive neuroprotective literature describing the efficacy of candidate drugs in focal ischemia has yet to lead to the development of effective stroke treatments. Ideally, the choice of drugs taken forward to clinical trial should be based on an unbiased assessment of all available data. Such an assessment might include not only the efficacy of a drug but also the in vivo characteristics and limits—in terms of time window, dose, species, and model of ischemia used—to that efficacy. To our knowledge, such assessments have not been made. Nicotinamide is a candidate neuroprotective drug with efficacy in experimental stroke, but the limits to and characteristics of that efficacy have not been fully described. Methods— Systematic review and modified meta-analysis of studies of experimental stroke describing the efficacy of nicotinamide. The search strategy ensured ascertainment of studies published in full and those published in abstract only. DerSimonian and Laird random effects meta-analysis was used to account for heterogeneity between studies. Results— Nicotinamide improved outcome by 0.287 (95% confidence interval 0.227 to 0.347) it was more effective in temporary ischemia models, after intravenous administration, in animals without comorbidities, and in studies published in full rather than in abstract. Studies scoring highly on a quality measure gave more precise estimates of the global effect. Conclusions— Meta-analysis provides an effective technique for the aggregation of data from experimental stroke studies. We propose new standards for reporting such studies and a systematic approach to aggregating data from the neuroprotective literature.
Publisher: Elsevier BV
Date: 09-1987
DOI: 10.1016/S0140-6736(87)92472-X
Abstract: Differences between male and female mammals are initiated by embryonic differentiation of the gonad into either a testis or an ovary. However, this may not be the sole determinant. There are reports that embryonic sex differentiation might precede and be independent of gonadal differentiation, but there is little molecular biological evidence for this. To test for sex differences in early-stage embryos, we separated male and female blastocysts using newly developed non-invasive sexing methods for transgenic mice expressing green fluorescent protein and compared the gene-expression patterns. From this screening, we found that the Fthl17 (ferritin, heavy polypeptide-like 17) family of genes was predominantly expressed in female blastocysts. This comprises seven genes that cluster on the X chromosome. Expression analysis based on DNA polymorphisms revealed that these genes are imprinted and expressed from the paternal X chromosome as early as the two-cell stage. Thus, by the time zygotic genome activation starts there are already differences in gene expression between male and female mouse embryos. This discovery will be important for the study of early sex differentiation, as clearly these differences arise before gonadal differentiation.
Publisher: SAGE Publications
Date: 19-06-2012
DOI: 10.1111/J.1747-4949.2012.00805.X
Abstract: The mortality and morbidity associated with stroke makes the development of new drugs a research priority. Recent unsuccessful clinical trials have reduced enthusiasm for the development of neuroprotective drugs. Here, we use empirical evidence derived from systematic reviews of stroke drug development to identify stages of drug development which might be improved. We then propose exemplar strategies which may be helpful, along with some basic economic modelling of what the impact of such strategies might be. This suggests that relatively straightforward measures might reduce the costs of drug development by $5.8 bn or 31%.
Publisher: AMPCo
Date: 05-2012
DOI: 10.5694/MJA12.10680
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2021
DOI: 10.1161/STROKEAHA.120.031742
Abstract: Circadian biology modulates almost all aspects of mammalian physiology, disease, and response to therapies. Emerging data suggest that circadian biology may significantly affect the mechanisms of susceptibility, injury, recovery, and the response to therapy in stroke. In this review erspective, we survey the accumulating literature and attempt to connect molecular, cellular, and physiological pathways in circadian biology to clinical consequences in stroke. Accounting for the complex and multifactorial effects of circadian rhythm may improve translational opportunities for stroke diagnostics and therapeutics.
Publisher: SAGE Publications
Date: 19-06-2012
Publisher: SAGE Publications
Date: 17-09-2008
Abstract: As a research community, we have failed to show that drugs, which show substantial efficacy in animal models of cerebral ischemia, can also improve outcome in human stroke. Accumulating evidence suggests this may be due, at least in part, to problems in the design, conduct, and reporting of animal experiments which create a systematic bias resulting in the overstatement of neuroprotective efficacy. Here, we set out a series of measures to reduce bias in the design, conduct and reporting of animal experiments modeling human stroke.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.THROMRES.2017.11.009
Abstract: Tumor-suppressing subchromosomal transferable fragment cDNA 6 (TSSC6) expression is restricted to hematopoietic organs and tissues where it plays a role in hematopoietic-cell function. The ADP purinergic receptor P2Y
Publisher: Oxford University Press (OUP)
Date: 03-05-2007
DOI: 10.1093/BRAIN/AWM083
Abstract: Induced hypothermia is proposed as a treatment for acute ischaemic stroke, but there have been too few clinical trials involving too few patients to draw any conclusions about the therapeutic benefit of cooling. Animal studies of induced hypothermia in focal cerebral ischaemia have tested cooling throughout a wide range of target temperatures, durations and intervals between stroke onset and the initiation of hypothermia. These studies, therefore, provide an opportunity to evaluate the effectiveness of different treatment strategies in animal models to inform the design of future clinical trials. We performed a systematic review and meta-analysis of the evidence for efficacy of hypothermia in animal models of ischaemic stroke, and identified 101 publications reporting the effect of hypothermia on infarct size or functional outcome, including data from a total of 3353 animals. Overall, hypothermia reduced infarct size by 44% [95% confidence interval (CI), 40-47%]. Efficacy was highest with cooling to lower temperatures (< or =31 degrees C), where treatment was started before or at the onset of ischaemia and in temporary rather than permanent ischaemia models. However, a substantial reduction in infarct volume was also observed with cooling to 35 degrees C (30% 95% CI, 21-39%), with initiation of treatment between 90 and 180 min (37% 95% CI, 28-46%) and in permanent ischaemia models (37% 95% CI, 30-43%). The effects of hypothermia on functional outcome were broadly similar. We conclude that in animal models of focal cerebral ischaemia, hypothermia improves outcome by about one-third under conditions that may be achievable for large numbers of patients with ischaemic stroke. Large randomized clinical trials testing the effect of hypothermia in patients with acute ischaemic stroke are warranted.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-1997
DOI: 10.1097/00001756-199709290-00018
Abstract: Although glial cell line-derived neurotrophic factor (GDNF) expression is low in the adult brain, its administration protects dopaminergic neurons against a range of insults, leading to the suggestion of a role in dopaminergic regeneration. If locally produced GDNF is to fulfil a role in dopaminergic regeneration after injury, it seems reasonable to hypothesize that its expression will increase after mechanical trauma. We have demonstrated that GDNF mRNA expression increases within 6 h of using a wire knife to injure adult mouse striatum. Expression doubles after 1 week and remains elevated for at least 1 month. Most GDNF expression is associated with haemosiderin-containing cells, indicating production by brain macrophages. GDNF production by macrophages may be essential for neural regeneration following CNS trauma.
Publisher: Springer Science and Business Media LLC
Date: 19-11-2013
DOI: 10.1038/NRNEUROL.2013.232
Abstract: Translational neuroscience is in the doldrums. The stroke research community was among the first to recognize that the motivations inherent in our system of research can cause investigators to take shortcuts, and can introduce bias and reduce generalizability, all of which leads ultimately to the recurrent failure of apparently useful drug candidates in clinical trials. Here, we review the evidence for these problems in stroke research, where they have been most studied, and in other translational research domains, which seem to be bedevilled by the same issues. We argue that better scientific training and simple changes to the way that we fund, assess and publish research findings could reduce wasted investment, speed drug development, and create a healthier research environment. For 'phase III' preclinical studies--that is, those studies that build the final justification for conducting a clinical trial--we argue for a need to apply the same attention to detail, experimental rigour and statistical power in our animal experiments as in the clinical trials themselves.
Publisher: Elsevier BV
Date: 09-2007
DOI: 10.1016/J.TINS.2007.06.009
Abstract: The development of stroke drugs has been characterized by success in animal studies and subsequent failure in clinical trials. Animal studies might have overstated efficacy, or clinical trials might have understated efficacy in either case we need to better understand the reasons for failure. Techniques borrowed from clinical trials have recently allowed the impact of publication and study-quality biases on published estimates of efficacy in animal experiments to be described. On the basis of these data, we propose minimum standards for the range and quality of pre-clinical animal data. We believe the adoption of these standards will lead to improved effectiveness and efficiency in the selection of drugs for clinical trials in stroke and in the design of those trials.
Publisher: Public Library of Science (PLoS)
Date: 31-05-2016
Publisher: SAGE Publications
Date: 13-01-2017
Abstract: To assess the true effect of novel therapies for ischaemic stroke, a positive control that can validate the experimental model and design is vital. Hypothermia may be a good candidate for such a positive control, given the convincing body of evidence from animal models of ischaemic stroke. Taking conditions under which substantial efficacy had been seen in a meta-analysis of hypothermia for focal ischaemia in animal models, we undertook three randomised and blinded studies examining the effect of hypothermia induced immediately following the onset of middle cerebral artery occlusion on infarct volume in rats (n = 15, 23, 264). Hypothermia to a depth of 33℃ and maintained for 130 min significantly reduced infarct volume compared to normothermia treatment (by 27–63%) and depended on ischaemic duration (F(3,244) = 21.242, p 0.05). However, the protective effect varied across experiments with differences in both the size of the infarct observed in normothermic controls and the time to reach target temperature. Our results highlight the need for s le size and power calculations to take into account variations between in idual experiments requiring induction of focal ischaemia.
Publisher: SAGE Publications
Date: 02-2009
DOI: 10.1111/J.1747-4949.2009.00241.X
Abstract: As a research community, we have failed to demonstrate that drugs that show substantial efficacy in animal models of cerebral ischemia can also improve outcome in human stroke. Accumulating evidence suggests that this may be due, at least in part, to problems in the design, conduct and reporting of animal experiments, which create a systematic bias resulting in the overstatement of neuroprotective efficacy. Here, we set out a series of measures to reduce bias in the design, conduct and reporting of animal experiments modeling human stroke.
Publisher: American Medical Association (AMA)
Date: 02-2016
Publisher: Oxford University Press (OUP)
Date: 02-1986
Abstract: Patients with phenylalanine hydroxylase deficiency show increased concentrations of biopterins and neopterins, and reduced concentrations of serotonin and catecholamines, when phenylalanine concentrations are raised. The pterin rise reflects increased synthesis of dihydroneopterin and tetrahydrobiopterin, and the amine fall a reduction in amine synthesis due to inhibition by phenylalanine of tyrosine and tryptophan transport into neurones. The pterin and amine changes appear to be independent of each other and are present in the central nervous system as well as the periphery they disappear when phenylalanine concentrations are reduced to normal. Patients with arginase deficiency show a similar amine disturbance but have normal pterin levels. The amine changes probably contribute neurological symptoms but pterin disturbance is not known to affect brain function. Patients with defective biopterin metabolism exhibit severely impaired amine synthesis due to tetrahydrobiopterin deficiency. Pterin concentrations vary with the site of the defect. Symptoms include profound hypokinesis and other features of basal ganglia disease. Neither symptoms nor amine changes are relieved by controlling phenylalanine concentrations. Patients with dihydropteridine reductase (DHPR) deficiency accumulate dihydrobiopterins and develop secondary folate deficiency which resembles that occurring in patients with defective 5,10-methylene tetrahydrofolate reductase activity. The latter disorder is also associated with Parkinsonism and defective amine and pterin turnover in the central nervous system, and a demyelinating illness occurs in both disorders. In DHPR deficiency cerebral calcification may develop in a similar distribution to that seen in congenital folate malabsorption and methotrexate toxicity. Symptoms are ameliorated by therapy with 5-formyltetrahydrofolate but exacerbated by folic acid.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2003
Publisher: Elsevier BV
Date: 07-2000
Publisher: BMJ
Date: 10-1993
DOI: 10.1136/ADC.69.4.433
Abstract: Two new cases of malonyl coenzyme A (CoA) decarboxylase deficiency are described. Hitherto, the worldwide experience of the disorder has been confined to reports on two affected Australian children. The new cases are Scots born and are the offspring of consanguinous parents of Scots/Irish origin. They were investigated during episodes of vomiting and febrile convulsions associated with concomitant developmental delay. Malonic aciduria and grossly reduced malonyl CoA decarboxylase activity were demonstrated and the total ion current chromatograms of urinary organic acid profiles obtained by gas chromatography-mass spectrometry are presented. The clinical and biochemical features of the Scots and Australian patients are compared.
Publisher: S. Karger AG
Date: 2005
DOI: 10.1159/000083878
Publisher: Springer Science and Business Media LLC
Date: 23-09-2009
Abstract: Phospholipase A 2 liberates free fatty acids and lysophospholipids upon hydrolysis of phospholipids and these products are often associated with detrimental effects such as inflammation and cerebral ischemia. The neuroprotective effect of neutral phospholipase from snake venom has been investigated. A neutral anticoagulant secretory phospholipase A 2 (nPLA) from the venom of Naja sputatrix (Malayan spitting cobra) has been found to reduce infarct volume in rats subjected to focal transient cerebral ischemia and to alleviate the neuronal damage in organotypic hippoc al slices subjected to oxygen-glucose deprivation (OGD). Real-time PCR based gene expression analysis showed that anti-apoptotic and pro-survival genes have been up-regulated in both in vivo and in vitro models. Staurosporine or OGD mediated apoptotic cell death in astrocytoma cells has also been found to be reduced by nPLA with a corresponding reduction in caspase 3 activity. We have found that a secretory phospholipase (nPLA) purified from snake venom could reduce infarct volume in rodent stroke model. nPLA, has also been found to reduce neuronal cell death, apoptosis and promote cell survival in vitro ischemic conditions. In all conditions, the protective effects could be seen at sub-lethal concentrations of the protein.
Publisher: BMJ
Date: 06-1993
DOI: 10.1136/JMG.30.6.465
Abstract: Two new mutations have been identified within the dihydropteridine reductase (DHPR) gene in two patients with DHPR deficiency. The total coding sequence of the cDNA has been screened by chemical cleavage of mismatch in both patients and selected portions of the cDNA have been sequenced. The first mutation identified causes a glycine to aspartic acid substitution at codon 23 and seems particularly frequent in Mediterranean patients. Its occurrence within a glycine string common to the amino-terminal region in NADH dependent enzymes suggests a possible causal mechanism for the defect. The second change involves a tryptophan to glycine substitution at codon 108 and is carried by both alleles in the second patient. It occurs in a motif which shows similarities with a region of dihydrofolate reductase (DHFR) and is highly conserved within different animal species.
Publisher: Humana Press
Date: 2010
Publisher: Elsevier BV
Date: 07-1987
DOI: 10.1016/S0140-6736(87)90792-6
Abstract: In the mammalian bloodstream, the sleeping sickness parasite Trypanosoma brucei is held poised for transmission by the activity of a tyrosine phosphatase, TbPTP1. This prevents differentiation of the transmissible "stumpy forms" until entry into the tsetse fly, whereupon TbPTP1 is inactivated and major changes in parasite physiology are initiated to allow colonization of the arthropod vector. Using a substrate-trapping approach, we identified the downstream step in this developmental signaling pathway as a DxDxT phosphatase, TbPIP39, which is activated upon tyrosine phosphorylation, and hence is negatively regulated by TbPTP1. In vitro, TbPIP39 promotes the activity of TbPTP1, thereby reinforcing its own repression, this being alleviated by the trypanosome differentiation triggers citrate and cis-aconitate, generating a potentially bistable regulatory switch. Supporting a role in signal transduction, TbPIP39 becomes rapidly tyrosine-phosphorylated during differentiation, and RNAi-mediated transcript ablation in stumpy forms inhibits parasite development. Interestingly, TbPIP39 localizes in glycosomes, peroxisome-like organelles that compartmentalize the trypanosome glycolytic reactions among other enzymatic activities. Our results invoke a phosphatase signaling cascade in which the developmental signal is trafficked to a unique metabolic organelle in the parasite: the glycosome. This is the first characterized environmental signaling pathway targeted directly to a peroxisome-like organelle in any eukaryotic cell.
Publisher: Wiley
Date: 02-1993
DOI: 10.1007/BF00711509
Publisher: Mary Ann Liebert Inc
Date: 12-1993
Abstract: Osmium tetroxide and hydroxylamine are used to detect mutations in DNA and RNA after hybridization of mutant and wild-type DNA. Mismatched T and C bases, respectively, are modified by these reagents and the DNA strand cleaved at the mismatched bases by subsequent treatment with piperidine. This allows detection and location of the mutation. Although most T.G mismatches have been reported to be reactive to osmium tetroxide, some have been reported to be unreactive. The aim of this study was to collect and analyze the reactive and unreactive T.G mismatches. We have collected sequence contexts of all reactive and unreactive T.G mismatches for analysis. This involves 10 unreactive T.G mismatches (plus one T.C) and 19 reactive T.G mismatches. Sequence effects of bases surrounding these mismatches must influence this reactivity. There must be many types of such sequence effects. We postulate that because of the dominance of 5' G bases near the T of unreactive T.G mismatches and the absence of 5' G bases in reactive T.G mismatches that the stacking of the 5' G on the mismatched T is the reason for this lack of reactivity in the majority of the cases studied here.
Publisher: Wiley
Date: 17-02-2006
DOI: 10.1002/ANA.20741
Abstract: Preclinical evaluation of neuroprotectants fostered high expectations of clinical efficacy. When not matched, the question arises whether experiments are poor indicators of clinical outcome or whether the best drugs were not taken forward to clinical trial. Therefore, we endeavored to contrast experimental efficacy and scope of testing of drugs used clinically and those tested only experimentally. We identified neuroprotectants and reports of experimental efficacy via a systematic search. Controlled in vivo and in vitro experiments using functional or histological end points were selected for analysis. Relationships between outcome, drug mechanism, scope of testing, and clinical trial status were assessed statistically. There was no evidence that drugs used clinically (114 drugs) were more effective experimentally than those tested only in animal models (912 drugs), for ex le, improvement in focal models averaged 31.3 +/- 16.7% versus 24.4 +/- 32.9%, p > 0.05, respectively. Scope of testing using Stroke Therapy Academic Industry Roundtable (STAIR) criteria was highly variable, and no relationship was found between mechanism and efficacy. The results question whether the most efficacious drugs are being selected for stroke clinical trials. This may partially explain the slow progress in developing treatments. Greater rigor in the conduct, reporting, and analysis of animal data will improve the transition of scientific advances from bench to bedside.
Publisher: Cold Spring Harbor Laboratory
Date: 15-07-2019
DOI: 10.1101/703355
Abstract: Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting are vital to this process it allows readers to assess the reliability of the findings, and repeat or build upon the work of other researchers. The NC3Rs developed the ARRIVE guidelines in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of the ARRIVE guidelines on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This Explanation and Elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2019, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and ex les of good reporting from the published literature.
Publisher: S. Karger AG
Date: 1984
DOI: 10.1159/000183133
Abstract: A study has been made of possible interrelationships between circulating vitamin A concentration and indicators of altered calcium homeostasis in 31 patients with stable chronic renal failure. Plasma retinol concentrations were high, possibly as a result of increased retinol-binding-protein concentrations secondary to renal failure. There was no correlation between retinol concentration and any other measurement, including vitamin A intake. However, there were significant correlations between plasma parathyroid hormone and calcium, phosphate, alkaline phosphatase, urea, and creatinine concentrations and those patients with radiological sub-periosteal erosions tended to have the highest concentrations of circulating parathyroid hormone. Our data give no support to the contention that vitamin A status has any bearing on the progression and severity of the hyperparathyroid bone disease of renal failure.
Publisher: Wiley
Date: 03-2002
DOI: 10.1046/J.1460-9568.2002.01914.X
Abstract: Injury to many regions of the central nervous system, including the striatum, results in a periwound or 'abortive' sprouting response. In order to directly evaluate whether macrophages play an important role in stimulating periwound sprouting, osteopetrotic (op/op) mice, which when young are deficient in a variety of macrophage subtypes, were given striatal wounds and the degree of dopaminergic sprouting subsequently assessed. Two weeks postinjury, significantly fewer wound macrophages were present in the striata of op/op mice compared with controls (144 +/- 30.1 in op/op mice vs. 416.6 +/- 82.3 in controls, P < 0.005, analysis performed on a section transecting the middle of the wound). Dopamine transporter immunohistochemistry revealed a marked decrease in the intensity of periwound sprouting in the op/op group of animals. Quantification of this effect using [H3]-mazindol autoradiography confirmed that periwound sprouting was reduced significantly in the op/op mice compared with controls (71.4 +/- 21.7 fmol/mg protein in op/op mice vs. 210.7 +/- 27.1 fmol/mg protein in controls, P < 0.0005). In the two groups of animals the magnitude of the sprouting response in in iduals was closely correlated with the number of wound macrophages (R = 0.83, R2 = 0.69). Our findings provide strong support for the crucial involvement of macrophages in inducing dopaminergic sprouting after striatal injury.
Publisher: American Chemical Society (ACS)
Date: 29-06-1993
DOI: 10.1021/BI00076A018
Abstract: Six mutations resulting in the recessive inherited disorder dihydropteridine reductase deficiency are reported, five of which are previously unknown. Two are nonsense mutations, resulting in premature termination of the protein, with the remaining four being missense mutations. The mutations found lie in the middle to 3' end of the dihydropteridine reductase reading frame, with the exception of one mutation which lies at codon 23, which is the only mutation found in more than one patient. The mutation pattern can be described as heterogeneous. The wild type and several of the mutant DHPR cDNA's were expressed in E. coli and the proteins purified and examined by a variety of techniques, including calculation of kinetic constants. One mutation (Gly23-->Asp) results in completely inactive protein, while a second (Trp108-->Gly) has substantial activity but does not completely dimerize. Both this mutant and a third, His158-->Tyr, are extremely susceptible to in vitro protease digestion, indicating that their three-dimensional structure has been altered. The protein studies underline the heterogeneous nature of DHPR mutations, in that the effects of different amino acid substitutions on the DHPR enzyme are varied.
Publisher: Wiley
Date: 08-06-1992
DOI: 10.1007/BF01800228
Abstract: We examined the effects of a combined education and token system intervention to improve adherence to inhaled corticosteroids for an 8-year-old girl and a 10-year-old boy with asthma. Adherence was measured by an electronic chronolog monitor, and disease outcome was assessed by repeated pulmonary function testing. A withdrawal design demonstrated improved adherence and, for 1 child, an associated improvement in pulmonary function occurred. Methodological and clinical implications are discussed, including variables other than adherence that may affect disease outcome.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2005
DOI: 10.1161/01.STR.0000166050.84056.48
Abstract: Background and Purpose— In contrast to tissue-type plasminogen activator (tPA), v ire bat ( Desmodus rotundus ) salivary plasminogen activator (desmoteplase [DSPA]) does not promote excitotoxic injury when injected directly into the brain. We have compared the excitotoxic effects of intravenously delivered tPA and DSPA and determined whether DSPA can antagonize the neurotoxic and calcium enhancing effects of tPA. Methods— The brain striatal region of wild-type c57 Black 6 mice was stereotaxically injected with N-methyl- d -Aspartate (NMDA) 24 hour later, mice received an intravenous injection of tPA or DSPA (10 mg/kg) and lesion size was assessed after 24 hours. Cell death and calcium mobilization studies were performed using cultures of primary murine cortical neurons. Results— NMDA-mediated injury was increased after intravenous administration of tPA, whereas no additional toxicity was seen after administration of DSPA. Unlike DSPA, tPA enhanced NMDA-induced cell death and the NMDA-mediated increase in intracellular calcium levels in vitro. Moreover, the enhancing effects of tPA were blocked by DSPA. Conclusions— Intravenous administration of tPA promotes excitotoxic injury, raising the possibility that leakage of tPA from the vasculature into the parenchyma contributes to brain damage. The lack of such toxicity by DSPA further encourages its use as a thrombolytic agent in the treatment of ischemic stroke.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.FORSCIINT.2007.01.031
Abstract: Use of the Positioning Ablation Laser MicroBeam (PALM) microlaser system to isolate specific cellular components from somatic cellular mixtures (blood and saliva) prior to DNA extraction and typing is compared with routine DNA extraction and typing of the same mixture s les. Mixtures of blood and saliva at differing ratios generated complex DNA profiles that included allele peaks originating from each of the donors, or just those of the major contributor. Isolation of cells with the PALM microlaser prior to DNA extraction allowed informative, single-source, DNA profiles to be generated from a known cell type/origin.
Publisher: Springer Science and Business Media LLC
Date: 13-03-2011
DOI: 10.1007/S00401-011-0815-1
Abstract: Lewy bodies are made from insoluble, phosphorylated α-synuclein, but the earliest changes that precipitate such pathology still remain conjecture. In this study, we quantify and identify relationships between the levels of the main pathologic form of phosphorylated α-synuclein over the course of Parkinson's disease in regions affected early through to end-stage disease. Brain tissue s les from 33 cases at different disease stages and 13 controls were collected through the Australian Network of Brain Banks. 500 mg of frozen putamen (affected preclinically) and frontal cortex (affected late) was homogenized, fractionated and α-synuclein levels evaluated using specific antibodies (syn-1, BD Transduction Laboratories S129P phospho-α-synuclein, Elan Pharmaceuticals) and quantitative western blotting. Statistical analyses assessed the relationship between the different forms of α-synuclein, compared levels between groups, and determined any changes over the disease course. Soluble S129P was detected in controls with higher levels in putamen compared with frontal cortex. In contrast, insoluble α-synuclein occurred in Parkinson's disease with a significant increase in soluble and lipid-associated S129P, and a decrease in soluble frontal α-synuclein over the disease course. Increasing soluble S129P in the putamen correlated with increasing S129P in other fractions and regions. These data show that soluble non-phosphorylated α-synuclein decreases over the course of Parkinson's disease, becoming increasingly phosphorylated and insoluble. The finding that S129P α-synuclein normally occurs in vulnerable brain regions, and in Parkinson's disease has the strongest relationships to the pathogenic forms of α-synuclein in other brain regions, suggests a propagating role for putamenal phospho-α-synuclein in disease pathogenesis.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2006
DOI: 10.1161/01.STR.0000226908.93295.9D
Abstract: Background and Purpose— [ 18 F]fluoromisonidazole (FMISO) positron emission tomography has been used to image hypoxia early after human stroke. To further study the role of hypoxia in stroke and the binding characteristics of FMISO, we aimed to develop [ 3 H]FMISO autoradiography in an animal stroke model. We hypothesized that [ 3 H]FMISO binding is prolonged, allowing correlation with 24-hour histology, and that there is no FMISO binding after effective reperfusion. Methods— Temporary middle cerebral artery (MCA) occlusion was performed in rats, followed by [ 3 H]FMISO administration. Tissue preparation for autoradiography and histology (from the same sections) was performed 2.5 hours after MCA occlusion (MCAo replicating [ 18 F]FMISO studies). Then, otherwise identical cohorts with tissue preparation at 2.5 or 24 hours were prepared. For reperfusion studies, animals had 1-hour MCAo, with [ 3 H]FMISO administered 1 hour after reperfusion. Results— [ 3 H]FMISO autoradiography provided a high-resolution image of hypoxia throughout the ischemic territory. Delaying animal death from 2.5 to 24 hours allowed histological changes of stroke to develop, without significantly altering either relative intensity (1.88±0.06 and 2.02±0.11, respectively) or volume (25±6 mm 3 and 28±5 mm 3 , respectively) of hypoxic binding. [ 3 H]FMISO binding did not occur after effective reperfusion, despite histological injury from the preceding MCAo. Conclusions— [ 3 H]FMISO autoradiography of hypoxia in experimental stroke offers several advantages. Bound FMISO is retained in tissues long term, enabling direct correlation with 24-hour histology. It is not bound after effective reperfusion. Therefore, positive [ 18 F]FMISO positron emission tomography studies in stroke patients are indicative of ongoing tissue hypoxia, not merely recent tissue injury.
Publisher: Wiley
Date: 30-04-2014
DOI: 10.1111/EBM2.3
Publisher: Elsevier BV
Date: 09-2006
DOI: 10.1016/J.JNEUMETH.2006.01.020
Abstract: Improving models of human stroke by the use of aged animals has been advocated however the commonly used rat middle cerebral artery thread-occlusion model has produced suboptimal stroke induction and excess mortality in aged rats. We report the development of a modified method for silicone-coating the tip of occluding threads which produces a malleable silicone-coated tip which is firmly bonded and of highly consistent diameter, and overcomes problems of thread insertion through the narrowed carotid canal found in aged animals. Comparison of stroke outcomes and mortality were made between these threads and heat-treated poly-L-lysine coated threads. The rate of successful stroke induction in aged rats was significantly improved (from 14% to 86%). Similarly, mortality fell from 21-31% to 3-7% or less in both young and old rats with or without diabetes and hypertension. An occluding thread tip diameter of 0.35-0.38 mm was optimal for induction of mid-sized strokes in both young and old rats. This method of thread manufacture overcomes problems of inconsistency of diameter and bonding of the silicone-coated tip, and these threads produce significant improvements in stroke induction by MCA occlusion, particularly in aged animals and those with co-morbidities.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.BRAINRES.2008.02.098
Abstract: Traumatic injury to the CNS results in peri-wound sprouting without significant axonal growth beyond the lesion edge. We have previously demonstrated that dopaminergic sprouting in the injured striatum follows an increasing gradient of BDNF and GDNF expression, with sprouting ceasing at the point of maximal factor expression. Progressively more complicated associations of sprouting fibers with increasingly activated microglia and macrophages suggest these factors are localized to the cell surface. To establish whether an increased concentration of immobilized BDNF and GDNF could stimulate axonal growth beyond the lesion edge, both factors were covalently attached to 10 microm polycarbonate microspheres. These spheres were implanted into the site of striatal injury 1 week after lesioning. A profusion of axons grew from the region of the lesion edge across the surface of the spheres. Some axons traversed the entire site of injury. Ultrastructural examination demonstrated the juxtaposition of regenerating axons to the surface of implanted spheres. CSPG immunostaining demonstrated that, in animals implanted with neurotrophin-microspheres, axonal growth was induced beyond the area of maximal CSPG reactivity. Surprisingly however, CSPG production at the wound edge was greater in control animals than those implanted with neurotrophin-microspheres. Overall, we show that axonal growth can be encouraged beyond the wound edge by an elevated concentration of immobilized trophic factors. This growth occurs despite the presence of inhibitory CSPGs at the lesion edge. Axonal growth appears to be stimulated mainly via the direct effects of neurotrophins. However, there also appears to be an indirect mechanism whereby neurotrophins reduce the synthesis of CSPG at the wound edge, making the peri-wound environment more permissive.
Publisher: SAGE Publications
Date: 08-2005
Publisher: Elsevier BV
Date: 1986
DOI: 10.1016/S0378-4347(00)83594-X
Abstract: We describe an isocratic, reversed-phase high-performance liquid chromatographic method for the simultaneous measurement of fully oxidised, dihydro- and tetrahydropterins in cerebrospinal fluid. Tetrahydrobiopterin is detected electrochemically using an ESA Coulochem detector in the redox mode. Dihydropterins are detected by fluorescence following post-column electrochemical oxidation, and fully oxidised pterins by their natural fluorescence. Apart from addition of antioxidants, no s le preparation is required. Comparison is made with methods requiring chemical oxidation for detection of tetrahydrobiopterin. Some results on children with neurological disease are presented.
Publisher: SAGE Publications
Date: 19-06-2012
DOI: 10.1111/J.1747-4949.2012.00802.X
Abstract: The main driving force behind the assessment of novel pharmacological agents in animal models of stroke is to deliver new drugs to treat the human disease rather than to increase knowledge of stroke pathophysiology. There are numerous animal models of the ischaemic process and it appears that the same processes operate in humans. Yet, despite these similarities, the drugs that appear effective in animal models have not worked in clinical trials. To date, tissue plasminogen activator is the only drug that has been successfully used at the bedside in hyperacute stroke management. Several reasons have been put forth to explain this, but the failure to consider comorbidities and risk factors common in older people is an important one. In this article, we review the impact of the risk factors most studied in animal models of acute stroke and highlight the parallels with human stroke, and, where possible, their influence on evaluation of therapeutic strategies.
Publisher: SAGE Publications
Date: 08-2005
Publisher: Springer Science and Business Media LLC
Date: 11-05-2016
Publisher: Wiley
Date: 06-09-2004
Publisher: Wiley
Date: 22-11-2023
DOI: 10.1002/JNR.25146
Abstract: Stroke therapy has largely focused on preventing damage and encouraging repair outside the ischemic core, as the core is considered irreparable. Recently, several studies have suggested endogenous responses within the core are important for limiting the spread of damage and enhancing recovery, but the role of blood flow and capillary pericytes in this process is unknown. Using the Rose Bengal photothrombotic model of stroke, we illustrate blood vessels are present in the ischemic core and peri-lesional regions 2 weeks post stroke in male mice. A FITC-albumin gel cast of the vasculature revealed perfusion of these vessels, suggesting cerebral blood flow (CBF) may be partially present, without vascular leakage. The length of these vessels is significantly reduced compared to uninjured regions, but the average width is greater, suggesting they are either larger vessels that survived the initial injury, smaller vessels that have expanded in size (i.e., arteriogenesis), or that neovascularization begins with larger vessels. Concurrently, we observed an increase in platelet-derived growth factor receptor beta (PDGFRβ, a marker of pericytes) expression within the ischemic core in two distinct patterns, one which resembles pericyte-derived fibrotic scarring at the edge of the core, and one which is vessel associated and may represent blood vessel recovery. We find little evidence for iding cells on these intralesional blood vessels 2 weeks post stroke. Our study provides evidence flow is present in PDGFRβ-positive vessels in the ischemic core 2 weeks post stroke. We hypothesize intralesional CBF is important for limiting injury and for encouraging endogenous repair following cerebral ischemia.
Publisher: SAGE Publications
Date: 18-07-2012
Abstract: In a rat model of stroke, the spatio-temporal distribution of α-smooth muscle actin-positive, (αSMA+) cells was investigated in the infarcted hemisphere (ipsilateral) and compared with the contralateral hemisphere. At day 3 postischemia, αSMA+ cells were concentrated in two main loci within the ipsilateral hemisphere (Area A) in the medial corpus callosum and (Area B) midway through the striatum adjacent to the lateral ventricle. By day 7 and further by day 14, fewer αSMA+ cells remained in Areas A and B but a steady increase in the peri-infarct was observed. αSMA+ cells also expressed glial acidic fibrillary protein [GFAP: αSMA+/GFAP+ (29%) αSMA+/GFAP– (71%) phenotypes] and feline leukemia virus C receptor 2 (FLVCR2), but not ED1(microglia) and established markers of pericytes normally located in vascular wall. αSMA+ cells were also located close to the subventricular zones (SVZ) adjacent to Areas A and B. In conclusion, αSMA + cells have been identified in a spatial and temporal sequence from the SVZ, at intermediate loci and in the vicinity of the peri-infarct. It is hypothesized that novel populations of αSMA+ precursors of pericytes are born on the SVZ, migrate into the peri-infarct region and are incorporated into new vessels of the peri-infarct regions.
Publisher: Elsevier BV
Date: 09-2003
DOI: 10.1016/S0967-5868(03)00004-3
Abstract: Following injury to the CNS, severed axons undergo a phase of abortive sprouting in the vicinity of the wound, but do not spontaneously re-grow or regenerate. From a long history of attempts to stimulate regeneraion, a major strategy that has been developed clinically is the implantation of tissue into denervated target regions. Unfortunately trials have so far not borne out the promise that this would prove a useful therapy for disorders such as Parkinson's disease. Many strategies have also been developed to stimulate the regeneration of axons across sites of injury, particularly in the spinal cord. Animal data have demonstrated that some of these approaches hold promise and that the spinal cord has a remarkable degree of intrinsic plasticity. Attempts are now being made to utilize experimental techniques in spinal patients.
Publisher: Wiley
Date: 08-1993
Abstract: Postmortem autoradiography was used to explore the mechanisms underlying L-dopa resistance in 2 patients with multiple-system atrophy. Indices of striatal presynaptic dopamine terminal loss and dopamine (D1 and D2) receptors were provided by 3H-mazindol, 3H-SCH 23390, and 125I-sulpiride binding. Neuronal loss, gliosis, and loss of postsynaptic D2 receptors preferentially involved the middle and posterior of the putamen, that region of the striatum most intimately involved in motor function. Loss of D1 receptors in the same area occurred in only 1 patient. These findings suggest that in multiple-system atrophy, resistance to L-dopa is due to a loss of putamental D2 receptors. The differential effects on D1 and D2 receptors in 1 patient implies that different subpopulations of striatal neurons were selectively involved.
Publisher: Wiley
Date: 14-07-2020
DOI: 10.1113/EP088870
Publisher: SAGE Publications
Date: 05-06-2013
Abstract: Hypertension is an established target for long-term stroke prevention but procedures for management of hypertension in acute stroke are less certain. Here, we analyze basic science data to examine the impact of hypertension on candidate stroke therapies and of anti-hypertensive treatments on stroke outcome. Methods: Data were pooled from 3,288 acute ischemic stroke experiments (47,899 animals) testing the effect of therapies on infarct size (published 1978-2010). Data were combined using meta-analysis and meta-regression, partitioned on the basis of hypertension, stroke model, and therapy. Results: Hypertensive animals were used in 10% of experiments testing 502 therapies. Hypertension was associated with lower treatment efficacy, especially in larger infarcts. Overall, anti-hypertensives did not provide greater benefit than other drugs, although benefits were evident in hypertensive animals even when given after stroke onset. Fifty-eight therapies were tested in both normotensive and hypertensive animals: some demonstrated superior efficacy in hypertensive animals (hypothermia) while others worked better in normotensive animals (tissue plasminogen activator, anesthetic agents). Discussion: Hypertension has a significant effect on the efficacy of candidate stroke drugs: standard basic science testing may overestimate the efficacy which could be reasonably expected from certain therapies and for hypertensive patients with large or temporary occlusions.
Publisher: Informa UK Limited
Date: 2015
DOI: 10.2147/NDT.S72925
Publisher: Elsevier BV
Date: 2011
Publisher: Public Library of Science (PLoS)
Date: 30-03-2010
Publisher: SAGE Publications
Date: 30-12-2009
Abstract: Erythropoietin (EPO) has shown promise as a neuroprotectant in animal models of ischemic stroke. EPO is thought not only to protect neurons from cell death, but also to promote regeneration after stroke. Here, we report a systematic review and meta-analysis of the efficacy of EPO in animal models of focal cerebral ischemia. Primary outcomes were infarct size and neurobehavioral outcome. Nineteen studies involving 346 animals for infarct size and 425 animals for neurobehavioral outcome met our inclusion criteria. Erythropoietin improved infarct size by 30.0% (95% CI: 21.3 to 38.8) and neurobehavioral outcome by 39.8% (33.7 to 45.9). Studies that randomized to treatment group or that blinded assessment of outcome showed lower efficacy. Erythropoietin was tested in animals with hypertension in no studies reporting infarct size and in 7.5% of the animals reporting neurobehavioral outcome. These findings show efficacy for EPO in experimental stroke, but when the impact of common sources of bias are considered, this efficacy falls, suggesting we may be overestimating its potential benefit. As common human co-morbidities may reduce therapeutic efficacy, broader testing to delineate the range of circumstances in which EPO works best would be beneficial.
Publisher: American Medical Association (AMA)
Date: 2014
DOI: 10.1001/JAMANEUROL.2013.4684
Abstract: Blockade of small GTPase-RhoA signaling pathway is considered a candidate translational strategy to improve functional outcome after spinal cord injury (SCI) in humans. Pooling preclinical evidence by orthodox meta-analysis is confounded by missing data (publication bias). To conduct a systematic review and meta-analysis of RhoA/Rho-associated coiled-coil containing protein kinase (ROCK) blocking approaches to (1) analyze the impact of bias that may lead to inflated effect sizes and (2) determine the normalized effect size of functional locomotor recovery after experimental thoracic SCI. We conducted a systematic search of PubMed, EMBASE, and Web of Science and hand searched related references. Studies were selected if they reported the effect of RhoA/ROCK inhibitors (C3-exoenzmye, fasudil, Y-27632, ibuprofen, siRhoA, and p21) in experimental spinal cord hemisection, contusion, or transection on locomotor recovery measured by the Basso, Beattie, and Bresnahan score or the Basso Mouse Scale for Locomotion. Two investigators independently assessed the identified studies. Details of in idual study characteristics from each publication were extracted and effect sizes pooled using a random effects model. We assessed risk for bias using a 9-point-item quality checklist and calculated publication bias with Egger regression and the trim and fill method. A stratified meta-analysis was used to assess the impact of study characteristics on locomotor recovery. Thirty studies (725 animals) were identified. RhoA/ROCK inhibition was found to improve locomotor outcome by 21% (95% CI, 16.0-26.6). Assessment of publication bias by the trim and fill method suggested that 30% of experiments remain unpublished. Inclusion of these theoretical missing studies suggested a 27% overestimation of efficacy, reducing the overall efficacy to a 15% improvement in locomotor recovery. Low study quality was associated with larger estimates of neurobehavioral outcome. Taking into account publication bias, RhoA/ROCK inhibition improves functional outcome in experimental SCI by 15%. This is a plausible strategy for the pharmacological augmentation of neurorehabilitation after human SCI. These findings support the necessity of a systematic analysis to identify preclinical bias before embarking on a clinical trial.
Publisher: Frontiers Media SA
Date: 2014
Publisher: Wiley
Date: 11-02-2016
DOI: 10.1111/JNC.13538
Abstract: We previously reported that conventional protein kinase C (cPKC)β participated in hypoxic preconditioning-induced neuroprotection against cerebral ischemic injury, and collapsin response-mediated protein 2 (CRMP2) was identified as a cPKCβ interacting protein. In this study, we explored the regulation of CRMP2 phosphorylation and proteolysis by cPKCβ, and their role in ischemic injury of oxygen-glucose deprivation (OGD)-treated cortical neurons and brains of mice with middle cerebral artery occlusion-induced ischemic stroke. The results demonstrated that cPKCβ-mediated CRMP2 phosphorylation via the cPKCβ-selective activator 12-deoxyphorbol 13-phenylacetate 20-acetate (DOPPA) and inhibition of calpain-mediated CRMP2 proteolysis by calpeptin and a fusing peptide containing TAT peptide and the calpain cleavage site of CRMP2 (TAT-CRMP2) protected neurons against OGD-induced cell death through inhibiting CRMP2 proteolysis in cultured cortical neurons. The OGD-induced nuclear translocation of the CRMP2 breakdown product was inhibited by DOPPA, calpeptin, and TAT-CRMP2 in cortical neurons. In addition, both cPKCβ activation and CRMP2 proteolysis inhibition by hypoxic preconditioning and intracerebroventricular injections of DOPPA, calpeptin, and TAT-CRMP2 improved the neurological deficit in addition to reducing the infarct volume and proportions of cells with pyknotic nuclei in the peri-infact region of mice with ischemic stroke. These results suggested that cPKCβ modulates CRMP2 phosphorylation and proteolysis, and cPKCβ activation alleviates ischemic injury in the cultured cortical neurons and brains of mice with ischemic stroke through inhibiting CRMP2 proteolysis by phosphorylation. Focal cerebral ischemia induces a large flux of Ca(2+) to activate calpain which cleaves collapsin response mediator (CRMP) 2 into breakdown product (BDP). Inhibition of CRMP2 cleavage by calpeptin and TAT-CRMP2 alleviates ischemic injury. Conventional protein kinase C (cPKC)β-mediated phosphorylation could inhibit CRMP2 proteolysis and alleviate ischemic injury in cultured cortical neurons and ischemic stroke-induced mice.
Publisher: Elsevier
Date: 2014
Publisher: Elsevier BV
Date: 11-1982
DOI: 10.1016/S0140-6736(82)90029-0
Abstract: Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols and is considered one of the most promising bioactive compounds in green tea because of its strong antioxidant properties. However, the protective role of EGCG in bovine oocyte in vitro maturation (IVM) has not been investigated. Therefore, we aimed to study the effects of EGCG on IVM of bovine oocytes. Bovine oocytes were treated with different concentrations of EGCG (0, 25, 50, 100, and 200 μM), and the nuclear and cytoplasmic maturation, cumulus cell expansion, intracellular reactive oxygen species (ROS) levels, total antioxidant capacity, the early apoptosis and the developmental competence of in vitro fertilized embryos were measured. The mRNA abundances of antioxidant genes (nuclear factor erythriod-2 related factor 2 [NRF2], superoxide dismutase 1 [SOD1], catalase [CAT], and glutathione peroxidase 4 [GPX4]) in matured bovine oocytes were also quantified. Nuclear maturation which is characterized by first polar body extrusion, and cytoplasmic maturation characterized by peripheral and cortical distribution of cortical granules and homogeneous mitochondrial distribution were significantly improved in the 50 μM EGCG-treated group compared with the control group. Adding 50 μM EGCG to the maturation medium significantly increased the cumulus cell expansion index and upregulated the mRNA levels of cumulus cell expansion-related genes (hyaluronan synthase 2, tumor necrosis factor alpha induced protein 6, pentraxin 3, and prostaglandin 2). Both the intracellular ROS level and the early apoptotic rate of matured oocytes were significantly decreased in the 50 μM EGCG group, and the total antioxidant ability was markedly enhanced. Additionally, both the cleavage and blastocyst rates were significantly higher in the 50 μM EGCG-treated oocytes after in vitro fertilization than in the control oocytes. The mRNA abundance of NRF2, SOD1, CAT, and GPX4 were significantly increased in the 50 μM EGCG-treated oocytes. In conclusion, 50 μM EGCG can improve the bovine oocyte maturation, and the protective role of EGCG may be correlated with its antioxidative property.
Publisher: Public Library of Science (PLoS)
Date: 09-03-2017
Publisher: Elsevier BV
Date: 02-2016
Publisher: Wiley
Date: 2006
DOI: 10.1002/MDS.21129
Abstract: Increased numbers of dopaminergic neurons are described in the striatum of patients with Parkinson's disease. In postmortem striatal tissue from Parkinson's disease patients with short disease duration ( or =16 years). The data suggest the possibility that the presence of large numbers of these striatal dopaminergic neurons may be harmful and may accelerate the disease process. Alternatively, these neurons may be lost to the disease process.
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.EXPNEUROL.2004.11.030
Abstract: Brain derived neurotrophic factor (BDNF) expression is significantly reduced in the Parkinson's disease substantia nigra. This neurotrophin has potent affects on dopaminergic neuron survival protecting them from the neurotoxins MPTP and 6-hydroxydopamine (6-OHDA) commonly used to create animal models of Parkinson's disease and also promoting dopaminergic axonal sprouting. In this study, we demonstrate that an antisense oligonucleotide infusion (200 nM for 28 days) to prevent BDNF production in the substantia nigra of rats mimics many features of the classical animal models of Parkinson's disease. 62% of antisense treated rats rotate (P < or = 0.05) in response to dopaminergic receptor stimulation by apomorphine. 40% of substantia nigra pars compacta tyrosine hydroxylase immunoreactive neurons are lost (P < or = 0.00001) and dopamine uptake site density measured by (3)H-mazindol autoradiography is reduced by 34% (P < or = 0.005). Loss of haematoxylin and eosin stained nigral neurons is significant (P < or = 0.0001) but less extensive (34%). These observations indicate that loss of BDNF expression leads both to down regulation of the dopaminergic phenotype and to dopaminergic neuronal death. Therefore, reduced BDNF mRNA expression in Parkinson's disease substantia nigra may contribute directly to the death of nigral dopaminergic neurons and the development of Parkinson's disease.
Publisher: SAGE Publications
Date: 04-01-2011
DOI: 10.1111/J.1747-4949.2010.00543.X
Abstract: Scientists tend to focus on the present and the future. But the practice of experimental stroke is not new. Here, we reflect on the changing landscape of the stroke laboratory over the past 2000-years, focusing on shifts in the rationale for undertaking experiments, the methodologies deployed and the colourful characters involved in this science.
Publisher: Springer Science and Business Media LLC
Date: 2003
DOI: 10.2165/00023210-200317140-00001
Abstract: Level 1 evidence now shows that thrombolysis in cases of acute ischaemic stroke is effective if administered within 3 hours of stroke onset. This benefit has been shown to be time dependent and potentially extends beyond 3 hours, with evidence that potentially viable penumbral tissue may be present in a significant proportion of cases well beyond 3-6 hours and, in isolated cases, perhaps up to 48 hours. This exposes a "stroke recovery gap", the difference observed between the clinical response to thrombolytic therapy in a given population of patients presenting with ischaemic stroke and the potential clinical recovery if all of the penumbra were salvaged under ideal circumstances. The means of bridging this "stroke recovery gap" using thrombolysis must involve extending the therapeutic time window (i.e. the time between stroke onset and administration of thrombolytics). Approaches to do this include the use of: (i) improved patient selection with modern neuroimaging techniques, particularly magnetic resonance imaging using perfusion-weighted image/diffusion-weighted image mismatch (ii) newer thrombolytic agents (iii) lower doses of these agents (iv) varied methods of administration of thrombolytic therapy including combined intravenous and intra-arterial approaches and (v) adjunctive therapies such as neuroprotectants. Should these means of extending the time window for thrombolysis prove successful, a more widespread use of this form of acute stroke therapy will be possible.
Publisher: Springer Science and Business Media LLC
Date: 07-1993
DOI: 10.1203/00006450-199307000-00003
Abstract: Accurate diagnosis and management of inborn errors of monoamine neurotransmitter and tetrahydrobiopterin metabolism depend on reliable reference ranges of key metabolites. Cerebrospinal fluid (CSF) was collected in a standardized way from 73 children and young adults with neurologic disease, with strict exclusions. In each specimen, concentrations of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (HIAA), total neopterin, 7,8-dihydrobiopterin, and tetrahydrobiopterin (BH4) were measured using HPLC. There was a continuous decrement in CSF HVA, HIAA, and BH4 during the first few years of life this was independent of height (or length). Age-related reference ranges for each metabolite are given. Extensive correlations between HVA, HIAA, 7,8-dihydrobiopterin, and BH4 were further analyzed by multiple regression. Age and CSF BH4 were significant explanatory variables for CSF HIAA, but CSF HVA had only HIAA as a significant explanatory variable.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2014
DOI: 10.1161/STROKEAHA.114.006304
Abstract: Poststroke depression is a prevalent complication of stroke with unclear pathogenesis. The benefits of antidepressants in this context and their effects on stroke recovery other than effects on mood are not clearly defined, with some studies suggesting efficacy in improving functional outcome in both depressed and nondepressed stroke patients. We have analyzed the preclinical animal data on antidepressant treatment in focal cerebral ischemia, modeled±depression, to help inform clinical trial design. We performed a systematic review and meta-analysis of data from experiments testing the efficacy of antidepressants versus no treatment to reduce infarct volume or improve neurobehavioral or neurogenesis outcomes in animal models of stroke. We used random-effects metaregression to test the impact of study quality and design characteristics and used trim and fill to assess publication bias. We identified 44 publications describing the effects of 22 antidepressant drugs. The median quality checklist score was 5 of a possible 10 (interquartile range, 4–7). Overall, antidepressants reduced infarct volume by 27.3% (95% confidence interval, 20.7%–33.8%) and improved neurobehavioral outcomes by 53.7% (46.4%–61.1%). There was little evidence for an effect of selective serotonin reuptake inhibitors on infarct volume. For neurobehavioral outcomes there was evidence of publication bias. Selective serotonin reuptake inhibitors were the most frequently studied antidepressant subtype and improved neurobehavioral outcome by 51.8% (38.6%–64.9%) and increased neurogenesis by 2.2 SD (1.3–3.0). In line with current clinical data and despite some limitations, antidepressant treatments seem to improve infarct volume and neurobehavioral outcome in animal models of ischemic stroke.
Publisher: Public Library of Science (PLoS)
Date: 09-02-2017
Publisher: Wiley
Date: 10-2000
DOI: 10.1046/J.1460-9568.2000.00239.X
Abstract: After striatal injury, sprouting dopaminergic fibres grow towards and intimately surround wound macrophages which, together with microglia, express the dopaminergic neurotrophic factors glial cell line-derived neurotrophic factor (GDNF) and brain derived neurotrophic factor (BDNF). To evaluate the importance of these endogenously secreted neurotrophic factors in generating striatal peri-wound dopaminergic sprouting, the peri-wound expression of BDNF or GDNF was inhibited by intrastriatal infusion of antisense oligonucleotides for 2 weeks in mice. Knock-down of both BDNF and GDNF mRNA and protein levels in the wounded striatum were confirmed by in situ hybridization and enzyme-linked immunosorbent assay, respectively. Dopamine transporter immunohisto-chemistry revealed that inhibition of either BDNF or GDNF expression resulted in a marked decrease in the intensity of peri-wound sprouting. Quantification of this effect using [H3]-mazindol autoradiography confirmed that peri-wound sprouting was significantly reduced in mice receiving BDNF or GDNF antisense infusions whilst control infusions of buffered saline or sense oligonucleotides resulted in the pronounced peri-wound sprouting response normally associated with striatal injury. BDNF and GDNF thus appear to be important neurotrophic factors inducing dopaminergic sprouting after striatal injury.
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.JOCN.2005.07.005
Abstract: Stroke is one of the leading causes of mortality and morbidity. The stroke process triggers an inflammatory reaction that may last up to several months. Suppression of inflammation using a variety of drugs reduces infarct volume and improves clinical outcomes in animal models of stroke. This benefit occurs even with the initiation of therapy after 3 hours of onset of stroke, beyond the therapeutic window for thrombolysis with tPA. The use of neuroprotectants to suppress inflammation may widen the therapeutic time window for tPA while lessening its side-effects. Suppression of inflammation may also improve outcomes in animal models of haemorrhagic stroke. To date, clinical trials with anti-inflammatory agents in acute ischaemic stroke have failed to improve clinical outcomes. However, because of the potential for broader applicability across all aspects of stroke, a better understanding of anti-inflammatory mechanisms is important.
Publisher: Mary Ann Liebert Inc
Date: 05-2011
Abstract: Most cases of human spinal cord injury (SCI) are accompanied by continuing cord compression. Experimentally, compression results in rapid neurological decline over hours, suggesting a rise in intracanal pressure local to the site of injury. The aim of this study was to measure the rise in local intracanal pressure accompanying progressive canal occlusion and to determine the relationship between raised intracanal pressure and neurological outcome. We also aimed to establish whether hypothermia was able to reduce raised intracanal pressure. We demonstrate that, following SCI in F344 rats, local intracanal pressure remains near normal until canal occlusion exceeds 30% of diameter, whereupon a rapid increase in pressure occurs. Intracanal pressure appears to be an important determinant of neurological recovery, with poor long-term behavioural and histological outcomes in animals subject to 8 h of 45% canal occlusion, in which intracanal pressure is significantly elevated. In contrast, good neurological recovery occurs in animals with near normal intracanal pressure (animals undergoing 8 h of 30% canal occlusion or those undergoing immediate decompression). We further demonstrate that hypothermia is an effective therapy to control raised intracanal pressure, rapidly reducing elevated intracanal pressure accompanying critical (45%) canal occlusion to near normal. Overall these data indicate that following SCI only limited canal narrowing is tolerated before local intracanal pressure rapidly rises, inducing a sharp decline in neurological outcome. Raised intracanal pressure can be controlled with hypothermia, which may be a useful therapy to emergently decompress the spinal cord prior to surgical decompression.
Publisher: SAGE Publications
Date: 02-2012
Abstract: Combination therapy has been identified as a promising strategy to improve stroke management. We conducted a systematic review and meta-analysis of evidence from animal models of ischemic stroke to determine whether combining treatments improved efficacy. Multiple databases were searched and data were extracted from focal ischemia experiments comparing control groups, single treatments, and combination treatments. Of 11,430 papers identified, 142 met the inclusion criteria these tested 126 treatments in 373 experiments using 8,037 animals ( I 2 = 85 to 96%). Taken together, single treatments reduced infarct size by 20% and improved neurological score by 12% compared with control a second therapy improved efficacy by an additional 18% and 25%, respectively. Publication bias may affect combination efficacy for infarct size but not neurological score. Combining thrombolysis with other therapies may extend the time window from 4.4 to 8 hours in animal models, although testing beyond 6 hours is required to confirm this. Benefits of additional therapy decreased as the efficacy of the primary treatment increased, with combination efficacy reaching a ceiling at 60% to 80% protection. Combining treatments may bring benefits and extend the time window for treatment. More evidence is needed due to potential publication bias and heterogeneity.
Publisher: Wiley
Date: 30-03-2023
DOI: 10.1002/GLIA.24371
Abstract: Cerebral blood flow (CBF) is important for the maintenance of brain function and its dysregulation has been implicated in Alzheimer's disease (AD). Microglia associations with capillaries suggest they may play a role in the regulation of CBF or the blood–brain‐barrier (BBB). We explored the relationship between microglia and pericytes, a vessel‐resident cell type that has a major role in the control of CBF and maintenance of the BBB, discovering a spatially distinct subset of microglia that closely associate with pericytes. We termed these pericyte‐associated microglia (PEM). PEM are present throughout the brain and spinal cord in NG2DsRed × CX 3 CR1 +/GFP mice, and in the human frontal cortex. Using in vivo two‐photon microscopy, we found microglia residing adjacent to pericytes at all levels of the capillary tree and found they can maintain their position for at least 28 days. PEM can associate with pericytes lacking astroglial endfeet coverage and capillary vessel width is increased beneath pericytes with or without an associated PEM, but capillary width decreases if a pericyte loses a PEM. Deletion of the microglia fractalkine receptor (CX 3 CR1) did not disrupt the association between pericytes and PEM. Finally, we found the proportion of microglia that are PEM declines in the superior frontal gyrus in AD. In summary, we identify microglia that specifically associate with pericytes and find these are reduced in number in AD, which may be a novel mechanism contributing to vascular dysfunction in neurodegenerative diseases.
Publisher: Mary Ann Liebert Inc
Date: 08-2010
Abstract: Human spinal cord injury (SCI) is usually accompanied by persistent cord compression. Experimental data demonstrate that compression of the traumatized cord results in rapid neurological decline over hours. Undertaking decompression in humans within this time frame has proved impractical, with the time to surgery in studies of urgent decompression averaging between 10 and 24 h. There is, therefore, an important need for a therapy to prevent the neurological deterioration of patients prior to decompressive surgery. The aim of this study was to determine if hypothermia prevents compressive SCI, thereby limiting neurological decline. Rats were subjected to a moderate mid-thoracic SCI and spacers were inserted to compress the spinal cord by 45%. Decompression, by removal of the spacer, was performed immediately, and at 2 or 8 h post-injury. Hypothermia (33 degrees C) was commenced in half the animals at 30 mins post-injury and maintained for 7.5 h, with the other half remaining normothermic (37.3 degrees C). Motor recovery was assessed weekly, and the volume and area of tissue damage determined at the end of the 8-week study period. The results demonstrate that hypothermia significantly improves the behavioral and histological outcome of animals undergoing 8 h of compressive injury (the primary outcome measure). The hypothermia-treated group regained weight-supported locomotion (Basso-Beattie-Bresnahan [BBB] locomotor assessment score 9.5 +/- 0.9), while the normothermic group remained severely paraparetic (BBB score 5.3 +/- 0.6 p <or= 0.0005). Hypothermia significantly increased the volume and area of healthy tissue in the peri-injury region, as well as the volume of preserved white and grey matter. Overall, the data suggest that hypothermia may be a useful bridging therapy to prevent neurological decline prior to decompressive surgery.
Publisher: Mary Ann Liebert Inc
Date: 10-2008
Abstract: Inflammation in the CNS predominantly involves microglia and macrophages, and is believed to be a significant cause of secondary injury following trauma. This study compares the microglial and macrophage response in the rat brain and spinal cord following discrete mechanical injury to better appreciate the degree to which these cells could contribute to secondary damage in these areas. We find that, 1 week after injury, the microglial and macrophage response is significantly greater in the spinal cord compared to the brain. This is the case for injuries to both gray and white matter. In addition, we observed a greater inflammatory response in white matter compared to gray matter within both the brain and spinal cord. Because activated microglia and macrophages appear to be effectors of secondary damage, a greater degree of inflammation in the spinal cord is likely to result in more extensive secondary damage. Tissue saving strategies utilizing anti-inflammatory treatments may therefore be more useful in traumatic spinal cord than brain injury.
Publisher: Springer Science and Business Media LLC
Date: 10-2012
DOI: 10.1038/NATURE11556
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2009
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.NUCMEDBIO.2013.12.006
Abstract: Activated platelets are key players in thrombosis and inflammation. We previously generated single-chain antibodies (scFv) against ligand-induced binding sites (LIBS) on the highly abundant platelet glycoprotein integrin receptor IIb/IIIa. The aim of this study was the construction and characterisation of a novel (18)F PET radiotracer based on this antibody. ScFv(anti-LIBS) and control antibody mut-scFv were reacted with N-succinimidyl-4-[(18)F]fluorobenzoate (S[(18)F]FB). Radiolabeled scFv was incubated with in vitro formed platelet clots and injected into mice with FeCl(3) induced thrombus in the left carotid artery. Clots were imaged in the PET scanner and amount of radioactivity measured using an ionization chamber and image analysis. Assessment of vessel injury as well as the biodistribution of the radiolabeled scFv was studied. After incubation with increasing concentrations of (18)F-scFv(anti-LIBS) clots had retained significantly higher amounts of radioactivity compared to clots incubated with radiolabeled (18)F-mut-scFv (13.3 ± 3.8 vs. 3.6 ± 1 KBq, p < 0.05, n = 9, decay corrected). In the in vivo experiments we found an high uptake of the tracer in the injured vessel compared with the non-injured vessel, with 12.6 ± 4.7% injected dose per gram (ID/g) uptake in the injured vessel and 3.7 ± 0.9% ID/g in the non-injured vessel 5 minutes after injection (p < 0.05, n = 6). Our results show that the novel antibody radiotracer (18)F-scFv(anti-LIBS) is useful for the sensitive detection of activated platelets and thrombosis. We describe the first (18)F variant of a scFv(anti-LIBS) against activated platelets. This diagnostic agent could provide a powerful tool for the assessment of acute thrombosis and inflammation in patients in the future.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2013
Publisher: Elsevier BV
Date: 2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2004
Publisher: Wiley
Date: 14-07-2020
DOI: 10.1113/JP280389
Abstract: Reproducible science requires transparent reporting. The ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments) were originally developed in 2010 to improve the reporting of animal research. They consist of a checklist of information to include in publications describing in vivo experiments to enable others to scrutinise the work adequately, evaluate its methodological rigour, and reproduce the methods and results. Despite considerable levels of endorsement by funders and journals over the years, adherence to the guidelines has been inconsistent, and the anticipated improvements in the quality of reporting in animal research publications have not been achieved. Here, we introduce ARRIVE 2.0. The guidelines have been updated and information reorganised to facilitate their use in practice. We used a Delphi exercise to prioritise and ide the items of the guidelines into 2 sets, the ‘ARRIVE Essential 10,’ which constitutes the minimum requirement, and the ‘Recommended Set,’ which describes the research context. This ision facilitates improved reporting of animal research by supporting a stepwise approach to implementation. This helps journal editors and reviewers verify that the most important items are being reported in manuscripts. We have also developed the accompanying Explanation and Elaboration document, which serves (1) to explain the rationale behind each item in the guidelines, (2) to clarify key concepts, and (3) to provide illustrative ex les. We aim, through these changes, to help ensure that researchers, reviewers, and journal editors are better equipped to improve the rigour and transparency of the scientific process and thus reproducibility.
Publisher: Elsevier
Date: 2013
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.JOCN.2013.10.033
Abstract: To increase the percentage of acute stroke patients benefiting from thrombolysis, the utility of expanding the time window of treatment beyond 4.5 hours after stroke onset needs to be investigated. We aimed to identify the target population and the challenges of recruitment of patients for the time window beyond 4.5 hours. Extending the time for Thrombolysis in Emergency Neurological Deficits (EXTEND), a multicentre randomised controlled trial testing the efficacy of thrombolytic therapy in patients with clinically significant ischaemic penumbra between 4.5 to 9 hours after stroke onset, was used as a model to evaluate inclusion and exclusion criteria for late thrombolysis trials. Data from all stroke patients admitted to Austin Health over a 1 year period were retrospectively analysed. Case notes were examined to determine potential trial eligibility. Of 556 patients assessed, 95 (17%) presented during the EXTEND time window. Sixty-seven of these (70.5%) were wake-up strokes (WUS) and 28 (29.5%) arrived between 4.5 and 9 hours after symptoms onset. At least one exclusion criterion was found for 78 (82%) of them. Hence, 17 (3%) patients arrived within an appropriate time frame for the study without any exclusion criteria. Most of these (13) arrived outside routine MRI hours. The number of patients recruited would have increased more than three-fold if imaging had been available 24 hours, 7 days a week. A significant proportion (17%) of ischaemic stroke patients presented between 4.5 and 9 hours after stroke onset. The majority of these were WUS. The major challenge identified for patient recruitment was imaging availability.
Publisher: Wiley
Date: 11-2017
DOI: 10.1111/EPI.13908
Abstract: Current antiseizure therapy is ineffective in approximately one third of people with epilepsy and is often associated with substantial side effects. In addition, most current therapeutic paradigms offer treatment, but not cure, and no therapies are able to modify the underlying disease, that is, can prevent or halt the process of epileptogenesis or alleviate the cognitive and psychiatric comorbidities. Preclinical research in the field of epilepsy has been extensive, but unfortunately, not all the animal models being used have been validated for their predictive value. The overall goal of TASK2 of the AES/ILAE Translational Task Force is to organize and coordinate systematic reviews on selected topics regarding animal research in epilepsy. Herein we describe our strategy. In the first part of the paper we provide an overview of the usefulness of systematic reviews and meta-analysis for preclinical research and explain the essentials for their conduct. Then we describe in detail the protocol for a first systematic review, which will focus on the identification and characterization of outcome measures reported in animal models of epilepsy. The specific goals of this study are to define systematically the phenotypic characteristics of the most commonly used animal models, and to effectively compare these with the manifestations of human epilepsy. This will provide epilepsy researchers with detailed information on the strengths and weaknesses of epilepsy models, facilitating their refinement and future research. Ultimately, this could lead to a refined use of relevant models for understanding the mechanism(s) of the epilepsies and developing novel therapies.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2004
DOI: 10.1161/01.STR.0000121647.01941.BA
Abstract: Background and Purpose— The ischemic penumbra is a major focus of stroke research. 18 F-fluoromisonidazole ( 18 F-FMISO), a positron emission tomography (PET) marker of hypoxic cells, has shown promise as a technique to image the penumbra in humans. Our aim was to delineate the pattern of 18 F-FMISO binding in a rat middle cerebral artery transient thread-occlusion model, and correlate this with tissue outcome at 24 hours. We hypothesized that the pattern of 18 F-FMISO binding would mimic that seen in humans. Methods— Thirty-eight rats underwent 2 hours transient middle cerebral artery (MCA) occlusion, and then received 18 F-FMISO at time points from 0.5 to 22 hours post-MCA occlusion and were killed 2 hours later. Autoradiographic assessment of 18 F-FMISO binding and assessment (triphenyltetrazolium chloride) of the area of infarction were performed on tissue slices. Results— Until 1 hour after MCA occlusion, 18 F-FMISO binding was increased in the entire MCA territory, with little or no infarction visible. Over the next 5 hours, the pattern of binding evolved to a small rim of intensely binding tissue surrounding the infarct core, which itself showed reduced binding compared with the contralateral hemisphere. By 24 hours, there was minimal accumulation of 18 F-FMISO binding and a large area of infarction. Conclusions— The pattern of 18 F-FMISO binding rats reproduced the pattern seen in humans, consistent with this tracer being a marker of the ischemic penumbra in both species. This technique may have application in studying the ischemic penumbra in animal models, and correlating this with similar studies in humans.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2009
DOI: 10.1161/STROKEAHA.108.525386
Abstract: Background and Purpose— As a research community, we have failed to demonstrate that drugs which show substantial efficacy in animal models of cerebral ischemia can also improve outcome in human stroke. Summary of Review— Accumulating evidence suggests this may be due, at least in part, to problems in the design, conduct and reporting of animal experiments which create a systematic bias resulting in the overstatement of neuroprotective efficacy. Conclusions— Here, we set out a series of measures to reduce bias in the design, conduct and reporting of animal experiments modeling human stroke.
Publisher: Springer New York
Date: 2014
Publisher: Public Library of Science (PLoS)
Date: 10-11-2015
Publisher: Elsevier BV
Date: 11-2002
Abstract: Following injury to the mammalian CNS, axons sprout in the vicinity of the wound margin. Growth then ceases and axons fail to cross the lesion site. In this study, using dopaminergic sprouting in the injured striatum as a model system, we have examined the relationship of periwound sprouting fibers to reactive glia and macrophages. In the first week after injury we find that sprouting fibers form intimate relationships with activated microglia as they traverse toward the wound edge. Once at the wound edge, complicated plexuses of fibers form around in idual macrophages. Axons, however, fail to grow further into the interior of the wound despite the presence of many macrophages in this location. We find that the expression of BDNF by activated microglia progressively increases as the wound edge is approached, while GDNF expression by macrophages is highest at the immediate wound margin. In contrast, the expression of both factors is substantially reduced within the macrophage-filled interior of the wound. Our data suggest that periwound sprouting fibers grow toward the wound margin along an increasing trophic gradient generated by progressively microglial and macrophage activation. Once at the wound edge, sprouting ceases over macrophages at the point of maximal neurotrophic factor expression and further axonal growth into the relatively poor trophic environment of the wound core fails to occur.
Publisher: SAGE Publications
Date: 08-2005
Publisher: SAGE Publications
Date: 21-07-2010
Abstract: Thrombolysis with recombinant tissue plasminogen activator (rtPA) improves outcome in animal models of stroke and in clinical trial, but is associated with increased intracranial hemorrhage. Here, we explore the impact of biologic and experimental design factors on efficacy and bleeding. We conducted a systematic review of studies describing the effect of tPA in thrombotic occlusion models of ischemic stroke followed by random effects meta-analysis, meta-regression, and trim and fill. We identified 202, 66, 128, and 54 comparisons reporting infarct volume, neurobehavioral score, hemorrhage, and mortality, respectively. The rtPA reduced infarct volume by 25.2% (95% confidence interval=21.8 to 28.6, 3388 animals), improved neurobehavioral score by 18.0% (12.6% to 23.3%, n=1243), increased the risk of hemorrhage (odds ratio=1.71, 1.42 to 2.07, n=2833) and had no significant effect on mortality (odds ratio=0.82, 0.62 to 1.08, n=1274). There was an absolute reduction in efficacy of 1.1% (0.7% to 1.4%) for every 10 minutes delay to treatment. Cumulative meta-analysis showed that the estimate of efficacy fell as more data became available. Publication bias inflated efficacy by 5.1% (infarct volume) and 8.1% (neurobehavioral score). This data set was large enough to be adequately powered to estimate with precision the impact of biologic and experimental factors on the efficacy and safety of rtPA.
Publisher: Public Library of Science (PLoS)
Date: 30-03-2010
Publisher: SAGE Publications
Date: 03-01-2014
DOI: 10.1111/IJS.12224
Abstract: Hypothermia provides neuroprotection after cardiac arrest, hypoxic-ischemic encephalopathy, and in animal models of ischemic stroke. However, as drug development for stroke has been beset by translational failure, we sought additional evidence that hypothermia protects human neurons against ischemic injury. Human embryonic stem cells were cultured and differentiated to provide a source of neurons expressing β III tubulin, microtubule-associated protein 2, and the Neuronal Nuclei antigen. Oxygen deprivation, oxygen-glucose deprivation, and H 2 O 2 -induced oxidative stress were used to induce relevant injury. Hypothermia to 33°C protected these human neurons against H 2 O 2 -induced oxidative stress reducing lactate dehydrogenase release and Terminal deoxynucleotidyl transferase dUTP nick end labeling-staining by 53% ( P ≤ 0·0001 95% confidence interval 34·8–71·04) and 42% ( P ≤ 0·0001 95% confidence interval 27·5–56·6), respectively, after 24 h in culture. Hypothermia provided similar protection against oxygen-glucose deprivation (42%, P ≤ 0·001, 95% confidence interval 18·3–71·3 and 26%, P ≤ 0·001 95% confidence interval 12·4–52·2, respectively) but provided no protection against oxygen deprivation alone. Protection (21%) persisted against H 2 O 2 -induced oxidative stress even when hypothermia was initiated six-hours after onset of injury ( P ≤ 0·05 95% confidence interval 0·57–43·1). We conclude that hypothermia protects stem cell-derived human neurons against insults relevant to stroke over a clinically relevant time frame. Protection against H 2 O 2 -induced injury and combined oxygen and glucose deprivation but not against oxygen deprivation alone suggests an interaction in which protection benefits from reduction in available glucose under some but not all circumstances.
Publisher: Future Medicine Ltd
Date: 09-2007
Abstract: Neuroprotection is an attractive potential therapy for acute ischemic stroke and is based on the concept of the ischemic cascade. However, therapeutic use of neuroprotectants in human stroke has proved more difficult than initially realized. The turning point was the finding that an apparently ideal neuroprotectant, NXY-059, was not neuroprotective in human stroke following a number of well-conducted clinical trials. In spite of these difficulties, research in neuroprotection should continue but in a greatly modified form. A number of important issues need to be addressed, ranging from the quality of experimental studies through to the demonstration of compounds reaching the target ischemic penumbra. An incremental approach to neuroprotection research is outlined, including the demonstration of efficacy in human cell cultures and tissues.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-1995
DOI: 10.1097/00001756-199510020-00009
Abstract: The injury associated with implantation of an inert gelatin matrix (gel foam) into normal mouse striatum induces a long-lived increase in binding of [3H]mazindol to presynaptic dopamine uptake sites, probably due to proliferation of striatal dopaminergic terminals. Because of the known effects of leukaemia inhibitory factor (LIF) on catecholaminergic cells, we tested the hypothesis that LIF may alter the striatal dopaminergic response to injury in vivo. Application of LIF to mouse striatum in a gel foam implant abolished the usual injury induced proliferation of dopamine uptake sites. The ability of LIF to prevent proliferation of dopamine terminals may have important implications for our understanding of neural regeneration, the aetiology of Parkinson's disease and its treatment by intrastriatal grafting.
Publisher: Elsevier BV
Date: 07-1987
DOI: 10.1016/0009-8981(87)90081-7
Abstract: Measurement of tetrahydrobiopterin in cerebrospinal fluid requires careful handling of s les during storage and analysis. Addition of dithioerythritol and deoxygenation of the mobile phase with helium prevents breakdown of tetrahydrobiopterin during chromatography. Tetrahydrobiopterin in cerebrospinal fluid is unstable at room temperature, 100% being lost within 3.5 h, this breakdown does not generate equivalent quantities of dihydrobiopterin and biopterin. Addition of dithioerythritol and diethylenetriaminepenta-acetic acid to cerebrospinal fluid prevents breakdown of tetrahydrobiopterin for 6 mth at -70 degrees C and for up to 5 h at 4 degrees C. At room temperature less than 5% of tetrahydrobiopterin was lost after 2 h.
Publisher: Elsevier BV
Date: 09-1993
DOI: 10.1016/0006-8993(93)90830-G
Abstract: To test the hypothesis that proliferation of host dopaminergic tissue in response to injury plays an important role in the response to intrastriatal grafting, we transplanted autologous adrenal medullary to striatum in normal C57-black mice and compared this procedure with transplantation of non-dopaminergic tissue (frontal cortex) or a non-cellular matrix (Gelfoam). [3H]Mazindol autoradiography revealed that all three protocols resulted in a marked proliferation of dopamine uptake sites 10 months after transplantation.
Publisher: SAGE Publications
Date: 19-02-2014
Abstract: The use of systematic review and meta-analysis of preclinical studies has become more common, including those of studies describing the modeling of cerebrovascular diseases. Empirical evidence suggests that too many preclinical experiments lack methodological rigor, and this leads to inflated treatment effects. The aim of this review is to describe the concepts of systematic review and meta-analysis and consider how these tools may be used to provide empirical evidence to spur the field to improve the rigor of the conduct and reporting of preclinical research akin to their use in improving the conduct and reporting of randomized controlled trials in clinical research. As with other research domains, systematic reviews are subject to bias. Therefore, we have also suggested guidance for their conduct, reporting, and critical appraisal.
Publisher: SAGE Publications
Date: 19-05-2010
Abstract: No single animal model is able to encompass all of the variables known to affect human ischemic stroke. This review highlights the major strengths and weaknesses of the most commonly used animal models of acute ischemic stroke in the context of matching model and experimental aim. Particular emphasis is placed on the relationships between outcome and underlying vascular variability, physiologic control, and use of models of comorbidity. The aim is to provide, for novice and expert alike, an overview of the key controllable determinants of experimental stroke outcome to help ensure the most effective application of animal models to translational research.
Publisher: Wiley
Date: 25-10-2004
DOI: 10.1002/ANA.20265
Abstract: A contributing factor to the failure of trials of neuroprotectants in acute ischemic stroke may be the differing vulnerability to ischemia of white compared with gray matter. To address this issue, we determined to establish the existence of potentially viable tissue in white matter and its evolution to infarction or salvage in both gray and white matter compartments in patients with ischemic stroke. Twenty-seven patients (mean age, 73.4 years) at a median of 16.5 hours after symptom onset were studied using the hypoxic marker 18F-misonidazole with positron emission tomography (PET). Tissue was segmented using an magnetic resonance probabilistic map. Although there was a greater volume of initially "at-risk tissue" in gray matter (58.3 cm3, 29.9-93.0 cm3 than white matter (42.0 cm3, 15.8-74.0 cm3 p <0.001) at the time of PET imaging, a higher proportion of this was still potentially viable in white matter (41.4%, 4.6-74.5%) than in gray matter (23.6%, 3.2-61.1% p <0.05). However, a similar proportion in each compartment spontaneously survived. These data provide evidence for the existence of potentially salvageable tissue in human white matter and is consistent with it having a similar or even greater resistance to ischemia than gray matter. For the latter possibility, alternative therapeutic strategies may be required for its salvage.
Publisher: SAGE Publications
Date: 18-02-2014
Abstract: Background. Regular exercise reduces the risk of a first-ever stroke and is associated with smaller infarcts. Although evidence has suggested that therapeutic exercise following stroke is beneficial, we do not yet know whether exercise reduces stroke severity and improves functional recovery. The mechanisms underlying any benefit remain unclear. Objective. To conduct a systematic review and meta-analysis of studies testing exercise in animal models of ischemic stroke where outcomes were measured as infarct volume, neurobehavioral score, neurogenesis, or a combination of these. We also sought evidence of publication bias. Methods. We searched 3 online databases for publications reporting the use of exercise in focal cerebral ischemia. We used DerSimonian and Laird normalized random-effects meta-analysis and meta-regression to determine the impact of study quality and design on the efficacy of exercise. Results. Overall, exercise reduced infarct volume by 25.2% (95% confidence interval [CI] = 19.0%-31.3% 65 experiments and 986 animals) and improved neurobehavioral score by 38.2% (95% CI = 29.1%-47.3% 42 experiments n = 771). For both outcomes, larger effects were seen when exercise preceded ischemia rather than came after it. For neurobehavioral scores, we found evidence of publication bias. Reported study quality was moderate (median score 5/10). Both model-specific (eg, type of ischemia) and exercise-specific characteristics influenced reported outcome. Conclusion. Exercise, either before or after ischemia, reduced infarct volume and improved neurobehavioral score. However, overall estimates of efficacy were higher in studies at risk of bias, and for neurobehavioral outcomes, there was evidence of a substantial publication bias.
Publisher: Public Library of Science (PLoS)
Date: 23-08-2013
Publisher: Springer Science and Business Media LLC
Date: 1989
DOI: 10.1007/BF00444122
Publisher: Public Library of Science (PLoS)
Date: 14-07-2020
Publisher: Public Library of Science (PLoS)
Date: 14-07-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2008
DOI: 10.1161/STROKEAHA.108.515957
Abstract: Background and Purpose— The neutral results of the SAINT II trial have again highlighted difficulties translating neuroprotective efficacy from bench to bedside. Animal studies are susceptible to study quality biases, which may lead to overstatement of efficacy. We report the impact of study quality on published estimates of the efficacy of NXY-059 in animal models of stroke. Methods— We conducted a systematic review and stratified meta-analysis of published studies describing the efficacy of NXY-059 in experimental focal cerebral ischemia. Results— Overall, NXY-059 improved infarct volume by 43.3% (95% CI, 34.7 to 52.8). Only 2 of 9 publications reported randomization, concealment of treatment allocation, and blinded outcome assessment. Studies not reporting these quality items gave substantially higher estimates of efficacy than did higher-quality studies. Conclusions— The reported efficacy of NXY-059 in animal models of stroke is confounded by low study quality. The failure of SAINT II highlights the need for substantial improvements in the design, conduct, and reporting of animal studies journals can play an important role in this by adopting standards for animal studies similar to those agreed over 10 years ago for clinical trials.
Publisher: Public Library of Science (PLoS)
Date: 16-07-2013
Publisher: Cold Spring Harbor Laboratory
Date: 11-08-2022
DOI: 10.1101/2022.08.08.503250
Abstract: Cerebral blood flow is important for the maintenance of brain function and its dysregulation has been implicated in Alzheimer’s disease (AD). Subpopulations of microglia have well-characterised associations with the vasculature in the central nervous system but the precise relationship between microglia and cells which exist on the vasculature is not yet clear. In this study we explored the relationship between microglia and pericytes, a vessel-resident cell type that has a major role in the regulation of cerebral blood flow and maintenance of the blood brain barrier. Using fixed tissue sections and in vivo live imaging, we discovered a subset of microglia that closely associated with pericytes, termed PE ricyte-associated M icroglia (PEM). PEM are present throughout all regions of the brain and spinal cord in NG2DsRed x CX 3 CR1 +/GFP mice, and in the human frontal cortex. They reside adjacent to pericytes at all levels of the capillary tree and can maintain their position for at least 28 days. PEM associate with pericytes lacking astroglial endfeet coverage but are segregated from pericytes by capillary basement membranes and capillary vessel width is similarly increased beneath pericytes with or without an associated PEM. Deletion of the microglia fractalkine receptor (CX 3 CR1) did not disrupt the association between pericytes and PEM, suggesting the association is not reliant on fractalkine signalling. Finally, we found that the proportion of microglia that are capillary-associated and PEM declines in the superior frontal gyrus (SFG) in AD, which is exacerbated by the APOE ε3/ε4 genotype. In summary, we identify and characterise a subpopulation of microglia that specifically associate with pericytes and find this population is reduced in the SFG in AD. This reduction may be a novel mechanism contributing to vascular dysfunction in diseases such as AD.
Publisher: SAGE Publications
Date: 27-10-2010
Abstract: There is some evidence that in animal models of acute ischaemic stroke, combinations of neuroprotective agents might be more efficacious than the same agents administered alone. Hence, we developed pragmatic, empirical criteria based on therapeutic target, cost, availability, efficacy, administration, and safety to select drugs for testing in combination in animal models of acute stroke. Magnesium sulphate, melatonin, and minocycline were chosen from a library of neuroprotective agents, and were tested in a more ‘realistic’ model favoured by the STAIR (Stroke Therapy Academic Industry Roundtable). Outcome was assessed with infarct volume, neurologic score, and two newly developed scales measuring general health and physiologic homeostasis. Owing to the failure to achieve neuroprotection in aged, hypertensive animals with drug delivery at 3 hours, the bar was lowered in successive experiments to determine whether neuroprotection could be achieved under conditions more conducive to recovery. Testing in younger animals showed more favourable homeostasis and general health scores than did testing in older animals, but infarct volume and neurologic scores did not differ with age, and treatment efficacy was again not shown. Testing with shorter occlusions resulted in smaller infarct volumes nevertheless, treatment efficacy was still not observed. It was concluded that this combination, in these stroke models, was not effective.
Publisher: SAGE Publications
Date: 12-09-2010
Abstract: 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.
Publisher: Wiley
Date: 05-1993
DOI: 10.1007/BF00711667
Publisher: Public Library of Science (PLoS)
Date: 13-10-2015
Publisher: SAGE Publications
Date: 09-02-2005
Abstract: FK506 is a candidate drug for acute stroke. For such drugs, any decision to proceed to clinical trial should be based on a full and unbiased assessment of the animal data, and consideration should be given to the limitations of those data. Such an assessment should include not only the efficacy of a drug but also the in vivo characteristics and limits to that efficacy. Here we use systematic review and meta-analysis to assess the evidence for a protective effect of FK506 in animal models of stroke. In all, 29 studies were identified describing procedures involving 1759 animals. The point estimate for the effect of FK506 was a 31.3% (95% confidence interval 27.2% to 35.4%) improvement in outcome. Efficacy was higher with ketamine anaesthesia and temporary ischaemia and was lower in rats, in animals with comorbidities, and where outcome was measured as infarct size alone. Reported study quality was modest by clinical trial standards, and efficacy was lower in high-quality studies. These findings show a substantial efficacy for FK506 in experimental stroke, but raise concerns that our estimate of effect size might be too high because of factors such as study quality and possible publication bias.
Publisher: Springer Science and Business Media LLC
Date: 27-08-2015
DOI: 10.1038/SREP13428
Abstract: Biomedical research suffers from a dramatically poor translational success. For ex le, in ischemic stroke, a condition with a high medical need, over a thousand experimental drug targets were unsuccessful. Here, we adopt methods from clinical research for a late-stage pre-clinical meta-analysis (MA) and randomized confirmatory trial (pRCT) approach. A profound body of literature suggests NOX2 to be a major therapeutic target in stroke. Systematic review and MA of all available NOX2 -/y studies revealed a positive publication bias and lack of statistical power to detect a relevant reduction in infarct size. A fully powered multi-center pRCT rejects NOX2 as a target to improve neurofunctional outcomes or achieve a translationally relevant infarct size reduction. Thus stringent statistical thresholds, reporting negative data and a MA-pRCT approach can ensure biomedical data validity and overcome risks of bias.
Publisher: Public Library of Science (PLoS)
Date: 09-08-2013
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.BRAINRES.2009.06.102
Abstract: The hypoxia tracer fluorine-18 fluoromisonidazole ([18F]FMISO) and its tritiated counterpart ([(3)H]FMISO) have been used as markers of potentially salvageable brain (ischemic penumbra) after stroke. In experimental models, the dynamics and half-life of [3H]FMISO allow concurrent histology after 24 h. Our aim was to further validate these techniques, by determining the optimum tracer exposure interval to delineate ischemic penumbra, and the effects of prolonged exposure on tracer retention in permanent ischemia. Middle cerebral artery occlusion (MCAO) of varying durations was created in rats using the thread occlusion model. Autoradiography using objective thresholding to define tracer-retention volume was performed to determine the time course of tracer retention in hypoxic tissues and the duration of ongoing retention after bolus administration. An ischemic duration of 1/2. Two hour ischemia resulted in a volume equal to 'tissue at risk'. Twenty-four hour permanent ischemia resulted in tracer-retaining tissue volumes greater than final infarction. However, the use of more stringent thresholding of autoradiographic signal produced a volume of FMISO retention closely approximating infarct volume. The findings indicate that the timing of imaging is crucial, with an optimal imaging time of 2 h using the current threshold. Earlier imaging is limited by tracer dynamics with this particular agent, however autoradiography with a longer ischemic interval (permanent occlusion) is feasible with modified thresholds. These findings support a role for hypoxia tracers in providing new insight into the ischemic penumbra.
Publisher: Springer Science and Business Media LLC
Date: 21-07-2012
Publisher: Public Library of Science (PLoS)
Date: 17-12-2013
Publisher: Elsevier BV
Date: 06-1991
DOI: 10.1016/S0022-3476(05)82198-5
Abstract: Continuous venovenous hemofiltration was used to treat two neonates, one with maple syrup urine disease and the other with an inborn error of long-chain fatty acid oxidation. The latter infant had hypoglycemia, hyperammonemia and lactic acidosis. In both cases, acceptable biochemical control was achieved within 8 hours. This therapy offers the potential to overcome acute crises rapidly in a wide range of inborn errors of intermediary metabolism.
Publisher: SAGE Publications
Date: 21-04-2010
Abstract: Angiotensin-converting enzyme (ACE) inhibition can reduce stroke risk by up to 43% in humans and reduce the associated disability, and hence understanding the mechanism of improvement is important. In animals and humans, these effects may be independent of the blood pressure-lowering effects of ACE inhibition. Normotensive (Wistar–Kyoto (WKY)) and hypertensive (spontaneously hypertensive rat (SHR)) animals were treated with the ACE inhibitors ramipril or lisinopril for 7 or 42 days before 2 hours of transient middle cerebral artery occlusion (MCAo). Blood pressure, serum ACE, and blood glucose levels were measured and stroke infarct volume was recorded 24 hours after stroke. Despite greater reductions in blood pressure, infarct size was not improved by ACE inhibition in hypertensive animals. Short-term ACE inhibition produced only a modest reduction in blood pressure, but WKY rats showed marked reductions in infarct volume. Long-term ACE inhibition had additional reductions in blood pressure however, infarct volumes in WKY rats did not improve further but worsened. WKY rats differed from SHR in having marked cortical ACE activity that was highly sensitive to ACE inhibition. The beneficial effects of ACE inhibition on infarct volume in normotensive rats do not correlate with changes in blood pressure. However, WKY rats have ACE inhibitor-sensitive cortical ACE activity that is lacking in the SHR.
Publisher: SAGE Publications
Date: 29-09-2010
Abstract: The degree of cellular injury within the stroke ischaemic penumbra is controversial. Clinical and experimental studies using the hypoxia tracer fluoromisonidazole (FMISO) have shown retention of this tracer in the penumbra, but cellular outcome has not been well characterised. We hypothesised that macroscopically intact FMISO-retaining penumbral tissues would show evidence of microscopic injury, and that no FMISO retention would be seen in the infarct core. To determine the distribution of FMISO retention, a tritium-labelled tracer (hydrogen-3 FMISO ([ 3 H]FMISO)) was administered 5 minutes after induction of 2-hour temporary middle cerebral artery occlusion. Coregistered brain histology and autoradiography at 24 hours revealed marked retention of FMISO within the infarct. However, 48% of the FMISO-retaining tissue was not infarcted. Within this noninfarcted tissue, only 27% (17 of 64) of s led regions showed no evidence of neuronal loss, whereas 44% (28 of 64) showed injury to % of neurons within the s le. To determine whether FMISO retention occurred after the tissue was already committed to infarction, FMISO was administered 4 to 6 hours after the onset of permanent vessel occlusion. Intense FMISO retention was consistently seen throughout the infarct core. In conclusion, FMISO retention occurs both within the ischaemic penumbra and within the early infarct core. Most penumbral tissues show evidence of selective cellular injury.
Publisher: Portland Press Ltd.
Date: 13-10-2017
DOI: 10.1042/CS20160722
Abstract: Background: Findings from in vivo research may be less reliable where studies do not report measures to reduce risks of bias. The experimental stroke community has been at the forefront of implementing changes to improve reporting, but it is not known whether these efforts are associated with continuous improvements. Our aims here were firstly to validate an automated tool to assess risks of bias in published works, and secondly to assess the reporting of measures taken to reduce the risk of bias within recent literature for two experimental models of stroke. Methods: We developed and used text analytic approaches to automatically ascertain reporting of measures to reduce risk of bias from full-text articles describing animal experiments inducing middle cerebral artery occlusion (MCAO) or modelling lacunar stroke. Results: Compared with previous assessments, there were improvements in the reporting of measures taken to reduce risks of bias in the MCAO literature but not in the lacunar stroke literature. Accuracy of automated annotation of risk of bias in the MCAO literature was 86% (randomization), 94% (blinding) and 100% (s le size calculation) and in the lacunar stroke literature accuracy was 67% (randomization), 91% (blinding) and 96% (s le size calculation). Discussion: There remains substantial opportunity for improvement in the reporting of animal research modelling stroke, particularly in the lacunar stroke literature. Further, automated tools perform sufficiently well to identify whether studies report blinded assessment of outcome, but improvements are required in the tools to ascertain whether randomization and a s le size calculation were reported.
Publisher: Wiley
Date: 11-06-2023
DOI: 10.1002/GLIA.24208
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2013
Publisher: Public Library of Science (PLoS)
Date: 02-03-2010
Publisher: SAGE Publications
Date: 03-07-2012
DOI: 10.1111/J.1747-4949.2012.00834.X
Abstract: Hypothermia is a promising experimental treatment for acute ischemic stroke. Human trials are still at an early stage, with the focus now on using hypothermia in awake patients. Pethidine (meperidine) is the principle agent used to control shivering in humans however, whether it has any modulating effects on the neuroprotective efficacy of hypothermia is unknown. The aim of this study was to determine if pethidine influences the neuroprotective effect of hypothermia in experimental stroke. Seventy-two male spontaneously hypertensive rats were anesthetized with isoflurane and randomly assigned to either normothermia (37·4°C rectal temperature) hypothermia (33°C maintained for 130 mins) normothermia plus pethidine (2·5 mg/kg) or hypothermia plus pethidine. Temporary (90 mins) endovascular occlusion of the middle cerebral artery was induced blinded to treatment allocation and was confirmed with laser Doppler flowmetry. Pethidine and cooling were started immediately after vessel occlusion. Animals in the normothermia group had active temperature management using a heat l and fan. Assessments of outcome were carried out 24 after the induction of injury. Thirteen animals met our prespecified criteria for exclusion, and data for 59 rats were presented here. Hypothermia was associated with a 63% reduction in infarct size, and pethidine had no significant impact on the efficacy of hypothermia. No effects were observed in neurobehavioral outcome or edema volume across experimental groups. The effects of hypothermia in a model of focal ischemia are not affected by administration of pethidine.
Publisher: Elsevier BV
Date: 03-2008
Publisher: Wiley
Date: 07-1999
DOI: 10.1046/J.1471-4159.1999.0730214.X
Abstract: We have previously shown that chronic treatment with the angiotensin-converting enzyme inhibitor perindopril increased striatal dopamine levels by 2.5-fold in normal Sprague-Dawley rats, possibly via modulation of the striatal opioid or tachykinin levels. In the present study, we investigated if this effect of perindopril persists in an animal model of Parkinson's disease, the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mouse. C57BL/6 mice were treated with the neurotoxin (30 mg/kg/day intraperitoneally) for 4 days and then left for 3 weeks to allow the degeneration of striatal dopaminergic terminals. At this time, the mice exhibited a 40% decrease in striatal dopamine content and an accompanying 46% increase in dopamine D2 receptor levels compared with control untreated mice. The dopamine content returned to control levels, and the increase in dopamine D2 receptor levels was attenuated in mice treated with perindopril (5 mg/kg/day orally for 7 days) 2 weeks after the last dose of MPTP. When the angiotensin-converting enzyme inhibitor was administered (5 mg/kg/day for 7 days) immediately after the cessation of the MPTP treatment, there was no reversal of the effect of the neurotoxin in decreasing striatal dopamine content. Our results demonstrate that perindopril is an effective agent in increasing striatal dopamine content in an animal model of Parkinson's disease.
Publisher: SAGE Publications
Date: 2017
Abstract: Application of acute therapies such as thrombolysis for ischaemic stroke (IS) is constrained because of diagnostic uncertainty and the dynamic nature of stroke biology. To investigate changes in blood proteins after stroke and as a result of thrombolysis treatment we performed label-free quantitative proteomics on serum s les using high-resolution mass spectrometry and long high-performance liquid chromatography gradient (5 hours) combined with a 50-cm column to optimise the peptide separation. We identified (false discovery rate [FDR]: 1%) and quantified a total of 574 protein groups from a total of 92 s les from 30 patients. Ten patients were treated by thrombolysis as part of a randomised placebo-controlled trial and up to 5 s les were collected from each in idual at different time points after stroke. We identified 26 proteins differently expressed by treatment group (FDR: 5%) and significant changes of expression over time for 23 proteins (FDR: 10%). Molecules such as fibrinogen and C-reactive protein showed expression profiles with a high-potential clinical utility in the acute stroke setting. Protein expression profiles vary acutely in the blood after stroke and have the potential to allow the construction of a stroke clock and to have an impact on IS treatment decision making.
Publisher: SAGE Publications
Date: 09-1983
DOI: 10.1177/000456328302000511
Abstract: We describe a rapid automated method for determination of retinol in 100 μl plasma. A lipid extract of plasma is analysed by reverse phase high pressure liquid chromatography using methanol-water as eluent. Automation of injection is achieved by adaptation of a Technicon AutoAnalyzer S ler 2 coupled with a Micromedic dilution system and a pneumatically actuated loop injector. Twenty patients' specimens can be analysed in 4 hours, including extraction time, standards, and quality controls, with one extract injected every 4 minutes.
Publisher: Springer Science and Business Media LLC
Date: 14-06-2011
Abstract: Around 15 years have now elapsed since thrombolysis was first shown to be effective for treating acute ischemic stroke, but therapeutic uptake has been modest. As outlined in this Review, research efforts are being directed towards rectifying this situation in a number of ways. First, strategies to enhance thrombolytic efficacy are being tested these include intravenous and intra-arterial bridging protocols, sonothrombolysis, and the use of alternative thrombolytic agents. Second, means of extending the 4.5-h therapeutic time window up to 6 h, or even up to 9 h in patients selected on the basis of imaging, are being investigated in clinical trials. Prolongation of the time window using neuroprotection to 'freeze' penumbral tissue is also being attempted. Third, attempts are underway to reduce the risk of symptomatic intracerebral hemorrhage (currently affecting about 7% of cases) by refining imaging selection criteria, and through the use of alternative thrombolytic agents, lower doses of tissue plasminogen activator, blood-based biomarkers, and neuroprotectants. Last, in an effort to include more people within the currently accepted therapeutic time window, improvements in prehospital management strategies are being introduced. Elimination of prehospital and in-hospital delays is an urgent priority.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2009
DOI: 10.1161/STROKEAHA.108.541128
Abstract: The initial Stroke Therapy Academic Industry Roundtable (STAIR) recommendations published in 1999 were intended to improve the quality of preclinical studies of purported acute stroke therapies. Although recognized as reasonable, they have not been closely followed nor rigorously validated. Substantial advances have occurred regarding the appropriate quality and breadth of preclinical testing for candidate acute stroke therapies for better clinical translation. The updated STAIR preclinical recommendations reinforce the previous suggestions that reproducibly defining dose response and time windows with both histological and functional outcomes in multiple animal species with appropriate physiological monitoring is appropriate. The updated STAIR recommendations include: the fundamentals of good scientific inquiry should be followed by eliminating randomization and assessment bias, a priori defining inclusion/exclusion criteria, performing appropriate power and s le size calculations, and disclosing potential conflicts of interest. After initial evaluations in young, healthy male animals, further studies should be performed in females, aged animals, and animals with comorbid conditions such as hypertension, diabetes, and hypercholesterolemia. Another consideration is the use of clinically relevant biomarkers in animal studies. Although the recommendations cannot be validated until effective therapies based on them emerge from clinical trials, it is hoped that adherence to them might enhance the chances for success.
Publisher: Wiley
Date: 14-01-2002
DOI: 10.1046/J.1440-1681.2002.03609.X
Abstract: 1. The ischaemic penumbra is defined as a moderately hypoperfused region that retains structural integrity but has lost function. In animal models of ischaemic stroke, this region is prone to recurrent anoxic depolarization and will become infarcted if reperfusion does not occur. In the macaque model, an ischaemic penumbra has been identified for up to 3 h after ischaemic stroke onset, whereas in selected human patients it may exist for up to 48 h. 2. Although most definitions of the ischaemic penumbra stress a time-brain volume concept, few incorporate the idea that selective and delayed neuronal injury plays an important role. Thus, in addition to necrotic cell death caused by acute injury, it is important to also consider delayed death mediated by caspase-dependent and -independent apoptotic pathways. 3. Salvage of penumbral tissue is possible if reperfusion (e.g. after thrombolysis) occurs. However, neurons within this salvaged region may be still at risk of further delayed neuronal injury. 4. In the present review, we aim to revisit the concept of the ischaemic penumbra and explore the role of selective and delayed neuronal injury in enlargement of the volume of infarction, as well as pathogenic mechanisms of white matter ischaemia. Both animal and human models of cerebral ischaemia imaged using magnetic resonance and positron emission tomography techniques will be discussed.
Publisher: Informa UK Limited
Date: 09-2013
Publisher: SAGE Publications
Date: 12-06-2012
DOI: 10.1111/J.1747-4949.2012.00797.X
Abstract: Stem cell therapy holds great promise in medicine, but clinical development should be based on a sound understanding of potential weaknesses in supporting experimental data. The aim of this article was to provide a systematic overview of evidence relating to the efficacy of stem cell-based therapies in animal models of stroke to foster the clinical application of stem cell-based therapies and to inform the design of large-scale clinical trials. We conducted a systematic search for reports of experiments using stem cells in animal models of cerebral ischaemia, and performed DerSimmonian and Laird random effects meta-analysis. We assessed the impact of study characteristics, of publication bias and of measures to reduce bias. We identified 6059 publications, 117 met our prespecified inclusion criteria. One hundred eighty-seven experiments using 2332 animals described changes in structural outcome and 192 experiments using 2704 animals described changes in functional outcome. Median study quality score was 4 (interquartile range 3 to 6) and less than half of studies reported randomization or blinded outcome assessment only three studies reported a s le size calculation. Nonrandomized studies gave significantly higher estimates of improvement in structural outcome, and there was evidence of a significant publication bias. For structural outcome autologous (i.e. self-derived) stem cells were more effective than allogeneic (donor-derived) cells, but for functional outcome, the reverse was true. A significant dose–response relationship was observed only for structural outcome. For structural outcome, there was an absolute reduction in efficacy of 1.5% (−2.4 to −0.6) for each days delay to treatment functional outcome was independent of the time of administration. While stem cells appear to be of some benefit in animal models of stroke the internal and external validity of this literature is potentially confounded by poor study quality and by publication bias. The clinical development of stem cell-based therapies, in stroke and elsewhere, should acknowledge these potential weaknesses in the supporting animal data.
Publisher: Elsevier BV
Date: 09-1995
DOI: 10.1016/0006-8993(95)00677-I
Abstract: In rats with unilateral 6-hydroxydopamine lesions in the nigrostriatal pathway, injection of angiotensin II (2 nmol) into the unlesioned striatum elicited dose-related tight rotations ipsilateral to the lesion. This rotation was suppressed by coadministration of the angiotensin AT1 receptor antagonist, losartan (2 nmol), which had no significant effect when injected alone. Preadministration of the dopamine antagonist, haloperidol (2 mg/kg i.p.) completely blocked angiotensin II-induced turning at doses of 0.3-3 nmol, and partially at 10 nmol. These results further confirm the hypothesis that Ang II is intrinsically involved in modulating dopamine release in the striatum, an effect which is mediated predominantly by AT1 receptors.
Publisher: Elsevier BV
Date: 11-1997
Abstract: Brain-derived neurotrophic factor (BDNF) promotes the survival and differentiation of nigral dopaminergic neurons and supports the activity of dopaminergic cells grafted into the striatum. However, little attention has been given to the physiological role of endogenous BDNF and its receptor TrkB within the nigrostriatal dopamine system. We know that striatal injury is followed by long-term stimulation of dopaminergic activity in the striatum, could BDNF play a role in this phenomenon? One week after physical injury to the striatum of C57/Black mice, just before dopaminergic activation becomes obvious, in situ hybridization on coronal sections through mouse striatum reveals that BDNF mRNA expression increases significantly before returning to basal levels within 1 month. Expression of mRNA for TrkB follows a very different pattern. No change of expression of the full-length and catalytically competent TrkBTK+ receptor is seen. However, expression of the truncated form of the receptor TrkTK-, which lacks the catalytic tyrosine kinase domain, does increase and stays elevated for at least 2 months after injury. When combined with observations of dopaminergic activation after striatal injury and the neuroprotective effects of BDNF introduced into the striatum, our findings suggest that BDNF and TrkBTK- do indeed play a role in dopaminergic regeneration and repair.
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2007
End Date: 2011
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2012
End Date: 2016
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2003
End Date: 2006
Funder: National Health and Medical Research Council
View Funded Activity