Reduction of animal use: experimental design and quality of experiments

Chronic H3R activation reduces L-Dopa-induced dyskinesia, normalizes cortical GABA and glutamate levels, and increases striatal dopamine D1R mRNA expression in 6-hydroxydopamine-lesioned male rats

RATIONALE

Dyskinesias induced by L-3,4-dihydroxyphenylalanine, L-Dopa (LIDs), are the major complication in the pharmacological treatment of Parkinson's disease. LIDs induce overactivity of the glutamatergic cortico-striatal projections, and drugs that reduce glutamatergic overactivity exert antidyskinetic actions. Chronic administration of immepip, agonist at histamine H₃ receptors (H₃R), reduces LIDs and diminishes GABA and glutamate content in striatal dialysates (Avila-Luna et al., Psychopharmacology 236: 1937-1948, 2019).

OBJECTIVES AND METHODS

In rats unilaterally lesioned with 6-hydroxydopamine in the substantia nigra pars compacta (SNc), we examined whether the chronic administration of immepip and their withdrawal modify LIDs, the effect of L-Dopa on glutamate and GABA content, and mRNA levels of dopamine D₁ receptors (D₁Rs) and H₃Rs in the cerebral cortex and striatum.

RESULTS

The administration of L-Dopa for 21 days induced LIDs. This effect was accompanied by increased GABA and glutamate levels in the cerebral cortex ipsi and contralateral to the lesioned SNc, and immepip administration prevented (GABA) or reduced (glutamate) these actions. In the striatum, GABA content increased in the ipsilateral nucleus, an effect prevented by immepip. L-Dopa administration had no significant effects on striatal glutamate levels. In lesioned and L-Dopa-treated animals, D₁R mRNA decreased in the ipsilateral striatum, an effect prevented by immepip administration.

CONCLUSIONS

Our results indicate that chronic H₃R activation reduces LIDs and the overactivity of glutamatergic cortico-striatal projections, providing further evidence for an interaction between D₁Rs and H₃Rs in the cortex and striatum under normal and pathological conditions.

Understanding the importance of quality control and quality assurance in preclinical PET/CT imaging

The fundamental principle of experimental design is to ensure efficiency and efficacy of the performed experiments. Therefore, it behoves the researcher to gain knowledge of the technological equipment to be used. This should include an understanding of the instrument quality control and assurance requirements to avoid inadequate or spurious results due to instrumentation bias whilst improving reproducibility. Here, the important role of preclinical positron emission tomography/computed tomography and the scanner's required quality control and assurance is presented along with the suggested guidelines for quality control and assurance. There are a multitude of factors impeding the continuity and reproducibility of preclinical research data within a single laboratory as well as across laboratories. A more robust experimental design incorporating validation or accreditation of the scanner performance can reduce inconsistencies. Moreover, the well-being and welfare of the laboratory animals being imaged is prime justification for refining experimental designs to include verification of instrumentation quality control and assurance. Suboptimal scanner performance is not consistent with the 3R principle (Replacement, Reduction, and Refinement) and potentially subjects animals to unnecessary harm. Thus, quality assurance and control should be of paramount interest to any scientist conducting animal studies. For this reason, through this work, we intend to raise the awareness of researchers using PET/CT regarding quality control/quality assurance (QC/QA) guidelines and instil the importance of confirming that these are routinely followed. We introduce a basic understanding of the PET/CT scanner, present the purpose of QC/QA as well as provide evidence of imaging data biases caused by lack of QC/QA. This is shown through a review of the literature, QC/QA accepted standard protocols and our research. We also want to encourage researchers to have discussions with the PET/CT facilities manager and/or technicians to develop the optimal designed PET/CT experiment for obtaining their scientific objective. Additionally, this work provides an easy gateway to multiple resources not only for PET/CT knowledge but for guidelines and assistance in preclinical experimental design to enhance scientific integrity of the data and ensure animal welfare.

Determination of Sample Size in Animal Experiments with Resource Equation Method and Power Analysis Abstract

Amaç Klinik öncesi araştırmalarda hayvan deneyleri sıklıkla kullanılmaktadır. Hayvan deneylerinin projelendirilmesinde örneklem büyüklüğünün belirlenmesi için kullanılan güncel yöntemlerden biri “kaynak eşitlik yöntemi”dir. Bu çalışmanın amacı; farklı araştırma tasarımları için kaynak eşitlik yöntemi ile örneklem büyüklüklerini ve bu örneklemlerin istatistiksel gücünü belirlemektir. Gereç ve Yöntemler Örneklem büyüklükleri bilim yazında bildirilen kaynak eşitlik yöntemi formülleri ile hesaplandı. Bu çalışmada eşitlikler tek grup tasarımları ve faktöriyel tasarımlar için genişletildi. Güç analizlerinin hesaplanmasında G*Power 3.1 yazılımı kullandı. Bulgular Sık kullanılan araştırma tasarımları için hesaplanan örneklem büyüklükleri tablolarda özetlendi. Örneklem büyüklükleri tek grup tasarımda 11 ile 21 arasında, ikiden fazla bağımsız grupta ise 15 ile 25 arasında değişmektedir. Tekrarlı ölçümlerde örneklem büyüklükleri bağımsız gruplara göre daha küçük bulundu. Faktöriyel tasarımlarda her bir alt grupta iki veya üç denek yeterli olduğu tespit edildi. Sonuç Kaynak eşitlik yöntemi ile belirlenen örneklem büyüklükleri tüm tasarımlarda, hayvan deneyleri için uygun büyüklüktedir. Yöntem sürekli değişkenler için kullanılabilir. Ancak istatistiksel güç değerleri %80 güç düzeyine göre genellikle düşüktür.

Evaluation of the Rheological Properties, Preclinical Safety, and Clinical Effectiveness of a New Dispersive Ophthalmic Viscoelastic Device for Cataract Surgery

Purpose

To evaluate the rheological properties of the ophthalmic viscoelastic device (OVD) PRO-149, its preclinical safety, and its effectiveness when used during cataract surgery in patients with age-related cataract.

Material and Methods

Control (HEC) and test (PRO-149) OVDs were compared through rheological measures, by two preclinical safety studies in rabbits, and under normal-use conditions during cataract removal and lens implantation in a parallel randomized clinical trial.

Results

Rheological properties were determined. Preclinical studies did not find any evidence of safety issues or toxicity. In the clinical trial, 36 subjects were included. After 29 days, there were no statistically significant differences in mean percentage of endothelial cell count change or in the postoperative intraocular pressure between groups. There were no significant differences between OVDs for any safety parameter studied. Finally, PRO-149 showed a statistically significant improvement in surgeon rating for ease of use during extraction (p < 0.05).

Conclusion

PRO-149 is a dispersive OVD. The rabbit models did not find evidence of clinical alterations or toxicity. The results of the clinical study support that the two studied OVDs were clinically similar in terms of safety and effectiveness for cataract surgery.

Trial Registration

The trial is registered at Clinical Trials.gov at NCT04702802 (21–01-11).

Validation of a preclinical dry eye model in New Zealand white rabbits during and following topical instillation of 1% ophthalmic atropine sulfate

BACKGROUND

The objective of this study was to validate an animal model for dry eye during and after the administration of 1% ophthalmic atropine sulfate (OAS) in New Zealand white (NZW) rabbits.

METHODS

OAS (1%) was applied three times per day to 30 eyes of 15 healthy NZW rabbits. Sacrifice, enucleation, and lacrimal gland removal took place on days 15, 21, and 30 (OAS group). A second group (n = 5) was used as control. Clinical evaluations took place on days 3, 10, 15, 18, 21, 24 and 30. The primary endpoints were: Schirmer I test, tear break-up time (TBUT), and corneal fluorescein staining. As secondary endpoints, clinical changes including intraocular pressure, and histopathology were evaluated.

RESULTS

While OAS was administered, the Schirmer I test showed a statistically significant reduction for OAS group versus control (p < 0.001), and versus basal production (p < 0.001). TBUT showed statistically significant differences between groups (days 3 and 10; p = 0.001) and versus basal values (day 3; p < 0.001). Fluorescein staining showed a statistically significant difference (day 3; p = 0.001). The most frequent clinical finding was conjunctival hyperemia (76.9% OAS vs. 20% control). For histopathology, all OAS subjects presented some degree of inflammation (86.7% minimal; 13.3% mild) whereas the control presented only 30% minimal inflammation. Goblet cell density showed no difference.

CONCLUSIONS

The effectiveness of the OAS dry eye model in NZW rabbits as reported in previous studies was confirmed, provided that the application of the drug is maintained throughout the intervention; it is not a viable model after OAS administration is suspended.

Meta-analysis of variation suggests that embracing variability improves both replicability and generalizability in preclinical research

The replicability of research results has been a cause of increasing concern to the scientific community. The long-held belief that experimental standardization begets replicability has also been recently challenged, with the observation that the reduction of variability within studies can lead to idiosyncratic, lab-specific results that cannot be replicated. An alternative approach is to, instead, deliberately introduce heterogeneity, known as "heterogenization" of experimental design. Here, we explore a novel perspective in the heterogenization program in a meta-analysis of variability in observed phenotypic outcomes in both control and experimental animal models of ischemic stroke. First, by quantifying interindividual variability across control groups, we illustrate that the amount of heterogeneity in disease state (infarct volume) differs according to methodological approach, for example, in disease induction methods and disease models. We argue that such methods may improve replicability by creating diverse and representative distribution of baseline disease state in the reference group, against which treatment efficacy is assessed. Second, we illustrate how meta-analysis can be used to simultaneously assess efficacy and stability (i.e., mean effect and among-individual variability). We identify treatments that have efficacy and are generalizable to the population level (i.e., low interindividual variability), as well as those where there is high interindividual variability in response; for these, latter treatments translation to a clinical setting may require nuance. We argue that by embracing rather than seeking to minimize variability in phenotypic outcomes, we can motivate the shift toward heterogenization and improve both the replicability and generalizability of preclinical research.

Safety and tolerability evaluation after repeated intravitreal injections of a humanized anti-VEGF-A monoclonal antibody (PRO-169) versus ranibizumab in New Zealand white rabbits

Background

To evaluate the retinal toxicity after repeated intravitreal injections of a humanized anti-VEGF-A monoclonal antibody (PRO-169) versus ranibizumab in New Zealand white (NZW) rabbit eyes.

Methods

NZW rabbits were injected intravitreally with PRO-169 (n = 12), 1.25 mg/0.05 ml or ranibizumab (n = 12), 0.5 mg/0.05 ml into the right eye (OD), whereas the left eye (OS) of each rabbit was used as control. Three consecutive injections were administered at 30-days intervals. An electroretinogram (ERG) was recorded 30 days after each injection. Clinical examination was conducted before and after injections, including intraocular pressure determination and eye fundus exploration. Eyes were enucleated and retina, cornea, conjunctiva, ciliary body and optic nerve were prepared for histopathology assessment.

Results

ERG of the experimental and control eyes in PRO-169 and ranibizumab groups were similar in amplitude and pattern throughout the follow-up period. Clinical examination found no alterations of intraocular pressure (IOP). No retinal damage was observed in both, the experimental and control eyes, of all the rabbits. The histopathologic studies showed similar results in both groups, showing no signs of structural damage.

Conclusions

Our study did not find evidence of retinal toxicity from a repeated intravitreal injection of PRO-169 or ranibizumab (Lucentis^®) in NZW rabbits. These findings support intravitreal PRO-169 as a safe candidate to develop as a future alternative for the treatment of retinal neovascularization diseases.

Topical Application of High-Dose Mesna Prevents Adhesion Formation: An Experimental Animal Study

BACKGROUND

Adhesion formation is a common complication of abdominal surgeries. Mesna is a drug with fibrinolytic properties which has been used in surgical field to facilitate tissue dissection. The aim of this experimental animal study was to investigate the effect of mesna on prevention of intra-abdominal adhesion in rats.

MATERIALS AND METHODS

Twenty-eight Wistar albino rats were used in the study. To create abdominal adhesion, cecum was abraded in all rats. No additional surgical procedure was performed other than adhesion in group 1 (only adhesion). In the other groups, rats were treated topically by administering 0.9% saline (group 2), 40 mg/kg mesna (group 3), and 400 mg/kg mesna (group 4). All rats were sacrificed on postoperative 21st day. Histopathological and macroscopic evaluations of adhesion formation were performed.

RESULTS

Quantity of adhesion scores (P = 0.022), severity of adhesion scores (P = 0.041), total adhesion scores (P = 0.023), and histopathological adhesion grading scores (P < 0.001) were reduced by 400 mg/kg mesna.

CONCLUSIONS

This is the first study for mesna on prevention of abdominal adhesion formation in rats. We concluded that dose-dependent reduction of adhesion was achieved by mesna. With future studies, topical administration of mesna during open abdominal surgeries may be used to prevent adhesion formation.

Prenatal exposure to oxcarbazepine increases hippocampal apoptosis in rat offspring

This study assessed apoptosis in the offspring of rats exposed to oxcarbazepine (OXC) from day 7 to 15 of gestation. Three groups of pregnant Wistar rats were used: 1) Control, treated with saline solution; 2) treated with 100 mg/kg OXC; 3) treated with 100 mg/kg of carbamazepine (CBZ, as a positive control for apoptosis); the route of administration was intragastric. Apoptosis was detected at three postnatal ages using the TUNEL technique in the CA1, and CA3 regions of the hippocampus and in the dentate gyrus (DG); neurogenesis was assessed in the DG using an antibody against doublecortin. The litter characteristics were recorded. OXC increased apoptosis in all regions (p < 0.01) at the three ages evaluated. Lamination disruption occurred in CA1 and CA3 due to the neuron absence and to ectopic neurons; there were also malformations in the dorsal lamina of the DG in 38% and 25% of the pups born from rats treated with OXC and CBZ respectively. CBZ also increased apoptosis. No clear effect on neurogenesis in the DG was observed. The size of the litter was smaller (p < 0.01) in the experimental groups. Nineteen-day OXC fetuses had low weight (p < 0.01), but 21 and 30 postnatal days old CBZ and OXC pups were overweight (p < 0.01). The results demonstrate that OXC administered during gestation is pro-apoptotic, alters the cytoarchitecture of the hippocampus, reduces litter size, and probably influences postnatal weight. We provide evidence of the proapoptotic effect of CBZ when administered early in gestation.

GABAergic imbalance is normalized by dopamine D1 receptor activation in the striatum contralateral to the cortical injury in motor deficit-recovered rats

RATIONALE

The sensorimotor cortex and the striatum are interconnected by the corticostriatal pathway, suggesting that cortical injury alters the striatal function, which may be modulated by dopamine.

OBJECTIVES

We studied whether the activation of dopamine D₁ receptors (D₁Rs) modulates the γ-aminobutyric acid (GABA) and glutamate levels in the striatum of recovered rats at 192 h after cortical injury.

METHODS

The D₁R agonist SKF-38393 (0, 2, 3, or 4 mg/kg) was administered at 24, 48, 96, and 192 h post-injury, and then rats were decapitated to determine GABA and glutamate levels and the levels of D₁R mRNA on both sides of the striatum.

RESULTS

GABAergic imbalance in the striatum contralateral to the injury site was normalized by the administration of the D₁R agonist, but this treatment did not produce a significant effect on glutamate levels, suggesting that glutamate was metabolized into GABA. The administration of SKF-38393 (2 mg/kg) decreased the levels of D₁R mRNA in the striatum contralateral to the injury, and this effect was blocked by the coadministration of the D₁R antagonist SCH-23390 (2 mg/kg). In the striatum ipsilateral to the injury, the D₁R agonist increased the D₁R mRNA levels, an effect that was blocked by SCH-23390.

CONCLUSION

The reversal of the GABAergic imbalance in the striatum contralateral to the cortical injury can be modulated by extrastriatal D₁R activation, and the D₁R agonist-induced increases in the D₁R mRNA levels in the striatum ipsilateral to the injury suggest that the striatum may be necessary to achieve functional recovery.

Chronic administration of the histamine H3 receptor agonist immepip decreases L-Dopa-induced dyskinesias in 6-hydroxydopamine-lesioned rats

RATIONALE

Histamine H₃ receptors (H₃Rs) are co-expressed with dopamine D₁ receptors (D₁Rs) by striato-nigral medium spiny GABAergic neurons, where they functionally antagonize D₁R-mediated responses.

OBJECTIVES AND METHODS

We examined whether the chronic administration of the H₃R agonist immepip modifies dyskinesias induced by L-3,4-dihydroxyphenylalanine, L-Dopa (LIDs), in rats lesioned with 6-hydroxydopamine in the substantia nigra pars compacta, and the effect of D₁R and H₃R co-activation on glutamate and GABA content in dialysates from the dorsal striatum of naïve rats.

RESULTS

The systemic administration (i.p.) of L-Dopa for 14 days significantly increased axial, limb, and orolingual abnormal involuntary movements (AIMs) compared with the vehicle group. The chronic administration of the H₃R agonist immepip alongside L-Dopa significantly decreased axial, limb, and orolingual AIMs compared with L-Dopa alone, but AIMs returned to previous values on immepip withdrawal. Chronic immepip was ineffective when administered prior to L-Dopa. The chronic administration of immepip significantly decreased GABA and glutamate content in striatal dialysates, whereas the administration of L-Dopa alone increased GABA and glutamate content.

CONCLUSIONS

These results indicate that chronic H₃R activation reduces LIDs, and the effects on striatal GABA and glutamate release provide evidence for a functional interaction between D₁Rs and H₃Rs.

Benefits of a factorial design focusing on inclusion of female and male animals in one experiment

Disease occurrence, clinical manifestations, and outcomes differ between men and women. Yet, women and men are most of the time treated similarly, which is often based on experimental data over-representing one sex. Accounting for persisting sex bias in biomedical research is the misconception that the analysis of sex-specific effects would double sample size and costs. We designed an analysis to test the potential benefits of a factorial study design in the context of a study including male and female animals. We chose a 2 × 2 factorial design approach to study the effect of treatment, sex, and an interaction term of treatment and sex in a hypothetical situation. We calculated the sample sizes required to detect an effect of a given magnitude with sufficient power and under different experimental setups. We demonstrated that the inclusion of both sexes in experimental setups, without testing for sex effects, requires no or few additional animals in our scenarios. These experimental designs still allow for the exploration of sex effects at low cost. In a confirmatory instead of an exploratory design, we observed an increase in total sample sizes by 33%, at most. Since the complexities associated with this mathematical model require statistical expertise, we generated and provide a sample size calculator for planning factorial design experiments. For the inclusion of sex, a factorial design is advisable, and a sex-specific analysis can be performed without excessive additional effort. Our easy-to-use calculation tool provides help in designing studies with both sexes and addresses the current sex bias in preclinical studies. KEY MESSAGES: • Both sexes should be included into animal studies. • Exploratory study of sex effects can be conducted with no or small increase in animal number. • Confirmatory analysis of sex effects requires maximum 33% more animals per study. • Our calculation tool supports the design of studies with both sexes.

Animals and Alternatives: Societal Expectations and Scientific Need

As Russell and Burch suggested more than 40 years ago, the most humane science is the best science. The path ahead is clear: pain and distress must be eliminated in animal experiments or reduced to an absolute minimum, and, as scientists, we must use the most humane approaches in our research. To accomplish the best science, we must train those who come after us in the principles and practice of humane science.

“Each of them necessitated the community's rejection of one time-honored scientific theory in favor of another incompatible with it. Each produced a consequent shift in the problems available for scientific scrutiny and in the standards by which the profession determined what should count as an admissible problem or as a legitimate problem-solution. And each transformed the scientific imagination in ways that we shall ultimately need to describe as a transformation of the world within which scientific work was done. Such changes, together with the controversies that almost always accompany them, are the defining characteristics of scientific revolutions.” (Thomas Kuhn, 1922–1996, on scientific revolutions)

“Change is scientific, progress is ethical; change is indubitable, whereas progress is a matter of controversy.” (Bertrand Russell, 1872–1970)

Ecological interactions between Gulf of Mexico snappers (Teleostei: Lutjanidae) and invasive red lionfish (Pterois volitans)

Indo-Pacific red lionfish (Pterois volitans) have invaded the western Atlantic, and most recently the northern Gulf of Mexico (nGOM), at a rapid pace. Given their generalist habitat affinities and diet, and strong ecological overlap with members of the commercially valuable snapper-grouper complex, increased density and abundance of lionfish could result in significant competitive interactions with nGOM commercially important species. We experimentally investigated the intensity of behavioral interactions between lionfish and indigenous, abundant and economically important juvenile nGOM red snapper (Lutjanus campechanus), and other increasingly abundant juvenile tropical snapper species (gray snapper—L. griseus and lane snapper—L. synagris) in large outdoor mesocosms to examine snapper vulnerabilities to lionfish competition. When paired with lionfish, red snapper swimming activity (i.e., time swimming and roving around experimental tank or at structure habitat during experiments) was significantly lower than in intraspecific control trials, but gray and lane snapper swimming activities in the presence of lionfish did not significantly differ from their intraspecific controls. Additionally in paired trials, red and lane snapper swimming activities were significantly lower than those of lionfish, while no significant difference in swimming activities was observed between lionfish and gray snapper. We found that red snapper prey consumption rates in the presence of lionfish were significantly lower than in their intraspecific 3-individual control trials, but when paired together no significant differences in prey consumption rates between red snapper and lionfish were observed. When paired with lane or gray snapper, lionfish were observed having comparatively higher prey consumption than snappers, or as observed in lionfish intraspecific 1-individual controls. However, lane and gray snapper consumption rates in the presence of lionfish did not significantly differ from those in intraspecific controls. These findings suggest that competition between juvenile snappers and invasive lionfish may be variable, with lionfish exhibiting differing degrees of competitive dominance and snappers exhibiting partial competitive vulnerability and resistance to lionfish. While the degree of intensity at which these interactions may occur in nGOM reefs may differ from those observed in our findings, this study enables greater understanding of the potential ecological effects of red lionfish on native reef fishes.

Researchers' attitudes to the 3Rs-An upturned hierarchy?

Animal use in biomedical research is generally justified by its potential benefits to the health of humans, or other animals, or the environment. However, ethical acceptability also requires scientists to limit harm to animals in their research. Training in laboratory animal science (LAS) helps scientists to do this by promoting best practice and the 3Rs. This study evaluated scientists' awareness and application of the 3Rs, and their approach to other ethical issues in animal research. It was based on an online survey of participants in LAS courses held in eight venues in four European countries: Portugal (Porto, Braga), Germany (Munich, Heidelberg), Switzerland (Basel, Lausanne, Zurich), and Denmark (Copenhagen). The survey questions were designed to assess general attitudes to animal use in biomedical research, Replacement alternatives, Reduction and Refinement conflicts, and harm-benefit analysis. The survey was conducted twice: immediately before the course ('BC', N = 310) and as a follow-up six months after the course ('AC', N = 127). While courses do appear to raise awareness of the 3Rs, they had no measurable effect on the existing low level of belief that animal experimentation can be fully replaced by non-animal methods. Most researchers acknowledged ethical issues with their work and reported that they discussed these with their peers. The level of an animal's welfare, and especially the prevention of pain, was regarded as the most pressing ethical issue, and as more important than the number of animals used or the use of animals as such. Refinement was considered more feasible than Replacement, as well as more urgent, and was also favoured over Reduction. Respondents in the survey reversed the 'hierarchy' of the 3Rs proposed by their architects, Russell and Burch, prioritizing Refinement over Reduction, and Reduction over Replacement. This ordering may conflict with the expectations of the public and regulators.

Dopamine D1 receptor activation maintains motor coordination and balance in rats

Dopamine (DA) modulates motor coordination, and its depletion, as in Parkinson's disease, produces motor impairment. The basal ganglia, cerebellum and cerebral cortex are interconnected, have functional roles in motor coordination, and possess dopamine D₁ receptors (D₁Rs), which are expressed at a particularly high density in the basal ganglia. In this study, we examined whether the activation of D₁Rs modulates motor coordination and balance in the rat using a beam-walking test that has previously been used to detect motor coordination deficits. The systemic administration of the D₁R agonist SKF-38393 at 2, 3, or 4 mg/kg did not alter the beam-walking scores, but the subsequent administration of the D₁R antagonist SCH-23390 at 1 mg/kg did produce deficits in motor coordination, which were reversed by the full agonist SKF-82958. The co-administration of SKF-38393 and SCH-23390 did not alter the beam-walking scores compared with the control group, but significantly prevented the increase in beam-walking scores induced by SCH-23390. The effect of the D₁R agonist to prevent and reverse the effect of the D₁R antagonist in beam-walking scores is an indicator that the function of D₁Rs is necessary to maintain motor coordination and balance in rats. Our results support that D₁Rs mediate the SCH-23390-induced deficit in motor coordination.

Relevance of bioreactors and whole tissue cultures for the translation of new therapies to humans

The purpose of this review is to provide a brief overview of bioreactor-based culture systems as alternatives to conventional two- and three-dimensional counterparts. The role, challenges, and future aspirations of bioreactors in the musculoskeletal field (e.g., cartilage, intervertebral disc, tendon, and bone) are discussed. Bioreactors, by recapitulating physiological processes, can be used effectively as part of the initial in vitro screening, reducing that way the number of animal required for preclinical assessment, complying with the 3R principles and, in most cases, allowing working with human tissues. The clinical significance of bioreactors is that, by providing more physiologically relevant conditions to customarily used two- and three-dimensional cultures, they hold the potential to provide a testing platform that is more predictable of a whole tissue response, thereby facilitating the screening of treatments before the initiation of clinical trials. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:10-21, 2018.

A novel model of highly lethal uncontrolled torso hemorrhage in swine

INTRODUCTION

A reproducible, lethal noncompressible torso hemorrhage model is important to civilian and military trauma research. Current large animal models balancing clinical applicability with standardization and internal validity. As such, large animal models of trauma vary widely in the surgical literature, limiting comparisons. Our aim was to create and validate a porcine model of uncontrolled hemorrhage that maximizes reproducibility and standardization.

METHODS

Seven Yorkshire-cross swine were anesthetized, instrumented, and splenectomized. A simple liver tourniquet was applied before injury to prevent unregulated hemorrhage while creating a traumatic amputation of 30% of the liver. Release of the tourniquet and rapid abdominal closure following injury provided a standardized reference point for the onset and duration of uncontrolled hemorrhage. At the moment of death, the liver tourniquet was quickly reapplied to provide accurate quantification of intra-abdominal blood loss. Weight and volume of the resected and residual liver segments were measured. Hemodynamic parameters were recorded continuously throughout each experiment.

RESULTS

This liver injury was rapidly and universally lethal (11.2 ± 4.9 min). The volume of hemorrhage (35.8% ± 6% of total blood volume) and severity of uncontrolled hemorrhage (100% of animals deteriorated to a sustained mean arterial pressure <35 mmHg for 5 min) were consistent across all animals. Use of the tourniquet effectively halted preprocedure and postprocedure blood loss allowing for accurate quantification of amount of hemorrhage over a defined period. In addition, the tourniquet facilitated the creation of a consistent liver resection weight (0.0043 ± 0.0003 liver resection weight: body weight) and as a percentage of total liver resection weight (27% ± 2.2%).

CONCLUSIONS

This novel tourniquet-assisted noncompressible torso hemorrhage model creates a standardized, reproducible, highly lethal, and clinically applicable injury in swine. Use of the tourniquet allowed for consistent liver injury and precise control over hemorrhage. Recorded blood loss was similar across all animals. Improving reproducibility and standardization has the potential to offer improvements in large animal translational models of hemorrhage.

LEVEL OF EVIDENCE

Level I.

Sensorimotor Intervention Recovers Noradrenaline Content in the Dentate Gyrus of Cortical Injured Rats

Nowadays, a consensus has been reached that designates the functional and structural reorganization of synapses as the primary mechanisms underlying the process of recovery from brain injury. We have reported that pontine noradrenaline (NA) is increased in animals after cortical ablation (CA). The aim of the present study was to explore the noradrenergic and morphological response after sensorimotor intervention (SMI) in rats injured in the motor cortex. We used male Wistar adult rats allocated in four conditions: sham-operated, injured by cortical ablation, sham-operated with SMI and injured by cortical ablation with SMI. Motor and somatosensory performance was evaluated prior to and 20 days after surgery. During the intervening period, a 15-session, SMI program was implemented. Subsequently, total NA analysis in the pons and dentate gyrus (DG) was performed. All groups underwent histological analysis. Our results showed that NA content in the DG was reduced in the injured group versus control, and this reduction was reverted in the injured group that underwent SMI. Moreover, injured rats showed reduction in the number of granule cells in the DG and decreased dentate granule cell layer thickness. Notably, after SMI, the loss of granule cells was reverted. Locus coeruleus showed turgid cells in the injured rats. These results suggest that SMI elicits biochemical and structural modifications in the hippocampus that could reorganize the system and lead the recovery process, modulating structural and functional plasticity.

Effects of dopamine D1 receptor activation and blockade on dopamine and noradrenaline levels in the rat brain

The noradrenergic and dopaminergic systems are associated with the motor system and have anatomical and functional connections that have not yet been studied. The present study aimed to examine the specific role of D1 receptors (D1Rs) on noradrenergic and dopaminergic responses in the rat brain. Male Wistar rats were assigned to eight groups to receive systemic injection of a D1R agonist (SKF-38393) at 0, 1, 5 or 10mg/kg or injection of a D1R antagonist (SCH-23390) at 0, 0.25, 0.5 or 1mg/kg. Dopamine (DA) and noradrenaline (NA) levels were measured using high-performance liquid chromatography. Injection of SKF-38393 alone at 1, 5 and 10mg/kg did not alter DA levels in the midbrain, cerebral cortex or pons, while it significantly increased these levels in the striatum (at 1 and 10mg/kg), hippocampus (at 1mg/kg) and cerebellum (at 1 and 5mg/kg). Administration of SKF-38393 at 1, 5, and 10mg/kg decreased the NA levels in the midbrain, pons, hippocampus (except at 1mg/kg) and cortex (except at 5mg/kg), whereas the opposite effect was observed in the striatum. SCH-23390 decreased the DA levels in the cortex (at 0.25 and 0.5mg/kg) and pons (at 0.5mg/kg). In contrast, 0.25, 0.5 and 1mg/kg SCH-23390 increased the DA levels in the cerebellum, whereas no differences from the control levels were observed for the DA levels in the striatum, midbrain and hippocampus. SCH-23390 at 0.5 and 1mg/kg increased the NA levels in the striatum. In contrast, the midbrain, hippocampus, cortex, pons and cerebellum did not exhibit altered NA levels. Our results demonstrate that the activation of D1Rs modulates the response of the noradrenergic system in nearly all of the investigated brain structures; thus, the blockade of D1Rs attenuates the effects induced by D1R activation.

Sensorimotor recovery from cortical injury is accompanied by changes on norepinephrine and serotonin levels in the dentate gyrus and pons

Monoamines such as norepinephrine (NE) and serotonin (5-HT) have shown to play an important role in motor recovery after brain injury. The effects elicited by these neurotransmitters have been reported as distal from the area directly affected. Remote changes may take place over minutes to weeks and play an important role in post-stroke recovery. However, the mechanisms involved in spontaneous recovery have not been thoroughly delineated. Therefore, we determined the NE and 5-HT content, in the pons and hippocampal dentate gyrus (DG) as well as motor deficit and spontaneous activity in rats after 3, 10 and 20 days cortical iron injection. Three days post-lesion the pontine NE content diminished, this effect was accompanied by deficient spontaneous activity and impaired sensorimotor evaluation. Ten and twenty days after lesion the NE levels were similar to those of control group, and animals also showed behavioral recovery. Monoamines content on DG 3 days post-lesion showed no differences as compared to controls. Interestingly, ten and twenty days after cortical injury, animals showed increased NE and 5-HT. These results suggest that behavioral recovery after brain damage involve changes on monoamines levels on DG, an important structure to plastic processes. In addition, the results herein support evidence to propose these neurotransmitters as key molecules to functional recovery in the central nervous system.

Translational challenges of animal models in Chagas disease drug development: a review

Chagas disease, or American trypanosomiasis, caused by Trypanosoma cruzi parasite infection is endemic in Latin America and presents an increasing clinical challenge due to migrating populations. Despite being first identified over a century ago, only two drugs are available for its treatment, and recent outcomes from the first clinical trials in 40 years were lackluster. There is a critical need to develop new drugs to treat Chagas disease. This requires a better understanding of the progression of parasite infection, and standardization of animal models designed for Chagas disease drug discovery. Such measures would improve comparison of generated data and the predictability of test hypotheses and models designed for translation to human disease. Existing animal models address both disease pathology and treatment efficacy. Available models have limited predictive value for the preclinical evaluation of novel therapies and need to more confidently predict the efficacy of new drug candidates in clinical trials. This review highlights the overall lack of standardized methodology and assessment tools, which has hampered the development of efficacious compounds to treat Chagas disease. We provide an overview of animal models for Chagas disease, and propose steps that could be undertaken to reduce variability and improve predictability of drug candidate efficacy. New technological developments and tools may contribute to a much needed boost in the drug discovery process.

Smad mediated regulation of inhibitor of DNA binding 2 and its role in phenotypic maintenance of human renal proximal tubule epithelial cells

The basic-Helix-Loop-Helix family (bHLH) of transcriptional factors plays a major role in regulating cellular proliferation, differentiation and phenotype maintenance. The downregulation of one of the members of bHLH family protein, inhibitor of DNA binding 2 (Id2) has been shown to induce de-differentiation of epithelial cells. Opposing regulators of epithelial/mesenchymal phenotype in renal proximal tubule epithelial cells (PTEC), TGFβ1 and BMP7 also have counter-regulatory effects in models of renal fibrosis. We investigated the regulation of Id2 by these growth factors in human PTECs and its implication in the expression of markers of epithelial versus myofibroblastic phenotype. Cellular Id2 levels were reduced by TGFβ1 treatment; this was prevented by co-incubation with BMP7. BMP7 alone increased cellular levels of Id2. TGFβ1 and BMP7 regulated Id2 through Smad2/3 and Smad1/5 dependent mechanisms respectively. TGFβ1 mediated Id2 suppression was essential for α-SMA induction in PTECs. Although Id2 over-expression prevented α-SMA induction, it did not prevent E-cadherin loss under the influence of TGFβ1. This suggests that the loss of gate keeper function of E-cadherin alone may not necessarily result in complete EMT and further transcriptional re-programming is essential to attain mesenchymal phenotype. Although BMP7 abolished TGFβ1 mediated α-SMA expression by restoring Id2 levels, the loss of Id2 was not sufficient to induce α-SMA expression even in the context of reduced E-cadherin expression. Hence, a reduction in Id2 is critical for TGFβ1-induced α-SMA expression in this model of human PTECs but is not sufficient in it self to induce α-SMA even in the context of reduced E-cadherin.

Robust and sensitive analysis of mouse knockout phenotypes

A significant challenge of in-vivo studies is the identification of phenotypes with a method that is robust and reliable. The challenge arises from practical issues that lead to experimental designs which are not ideal. Breeding issues, particularly in the presence of fertility or fecundity problems, frequently lead to data being collected in multiple batches. This problem is acute in high throughput phenotyping programs. In addition, in a high throughput environment operational issues lead to controls not being measured on the same day as knockouts. We highlight how application of traditional methods, such as a Student’s t-Test or a 2-way ANOVA, in these situations give flawed results and should not be used. We explore the use of mixed models using worked examples from Sanger Mouse Genome Project focusing on Dual-Energy X-Ray Absorptiometry data for the analysis of mouse knockout data and compare to a reference range approach. We show that mixed model analysis is more sensitive and less prone to artefacts allowing the discovery of subtle quantitative phenotypes essential for correlating a gene’s function to human disease. We demonstrate how a mixed model approach has the additional advantage of being able to include covariates, such as body weight, to separate effect of genotype from these covariates. This is a particular issue in knockout studies, where body weight is a common phenotype and will enhance the precision of assigning phenotypes and the subsequent selection of lines for secondary phenotyping. The use of mixed models with in-vivo studies has value not only in improving the quality and sensitivity of the data analysis but also ethically as a method suitable for small batches which reduces the breeding burden of a colony. This will reduce the use of animals, increase throughput, and decrease cost whilst improving the quality and depth of knowledge gained.

Substitute of Animals in Drug Research: An Approach Towards Fulfillment of 4R's

The preclinical studies for drug screening involve the use of animals which is very time consuming and expensive and at times leads to suffering of the used organism. Animal right activists around the world are increasingly opposing the use of animals. This has forced the researchers to find ways to not only decrease the time involved in drug screening procedures but also decrease the number of animals used and also increase the humane care of animals. To fulfill this goal a number of new in vitro techniques have been devised which are called 'Alternatives' or 'Substitutes' for use of animals in research involving drugs. These 'Alternatives' are defined as the adjuncts which help to decrease the use as well as the number of animals in biomedical research. Russell and Burch have defined these alternatives by three R's - Reduction, Refinement and Replacement. These alternative strategies include physico-chemical methods and techniques utilizing tissue culture, microbiological system, stem cells, DNA chips, micro fluidics, computer analysis models, epidemiological surveys and plant-tissue based materials. The advantages of these alternatives include the decrease in the number of animals used, ability to obtain the results quickly, reduction in the costs and flexibility to control the variables of the experiment. However these techniques are not glittering gold and have their own shortcomings. The disadvantages include the lack of an appropriate alternative to study the whole animal's metabolic response, inability to study transplant models and idiosyncratic responses and inability to study the body's handling of drugs and its subsequent metabolites. None-the-less these aalternative methods to certain extent help to reduce the number of animals required for research. But such alternatives cannot eliminate the need for animals in research completely. Even though no animal model is a complete set of replica for a process within a human body, the intact animal does provide a better model of the complex interaction of the physiological processes.

Aspects of experimental design for plant metabolomics experiments and guidelines for growth of plant material

Experiments involve the deliberate variation of one or more factors in order to provoke responses, the identification of which then provides the first step towards functional knowledge. Because environmental, biological, and/or technical noise is unavoidable, biological experiments usually need to be designed. Thus, once the major sources of experimental noise have been identified, individual samples can be grouped, randomised, and/or pooled. Like other 'omics approaches, metabolomics is characterised by the numbers of analytes largely exceeding sample number. While this unprecedented singularity in biology dramatically increases false discovery, experimental error can nevertheless be decreased in plant metabolomics experiments. For this, each step from plant cultivation to data acquisition needs to be evaluated in order to identify the major sources of error and then an appropriate design can be produced, as with any other experimental approach. The choice of technology, the time at which tissues are harvested, and the way metabolism is quenched also need to be taken into consideration, as they decide which metabolites can be studied. A further recommendation is to document data and metadata in a machine readable way. The latter should also describe every aspect of the experiment. This should provide valuable hints for future experimental design and ultimately give metabolomic data a second life. To facilitate the identification of critical steps, a list of items to be considered before embarking on time-consuming and costly metabolomic experiments is proposed.

Optimising experimental design for high-throughput phenotyping in mice: a case study

To further the functional annotation of the mammalian genome, the Sanger Mouse Genetics Programme aims to generate and characterise knockout mice in a high-throughput manner. Annually, approximately 200 lines of knockout mice will be characterised using a standardised battery of phenotyping tests covering key disease indications ranging from obesity to sensory acuity. From these findings secondary centres will select putative mutants of interest for more in-depth, confirmatory experiments. Optimising experimental design and data analysis is essential to maximise output using the resources with greatest efficiency, thereby attaining our biological objective of understanding the role of genes in normal development and disease. This study uses the example of the noninvasive blood pressure test to demonstrate how statistical investigation is important for generating meaningful, reliable results and assessing the design for the defined research objectives. The analysis adjusts for the multiple-testing problem by applying the false discovery rate, which controls the number of false calls within those highlighted as significant. A variance analysis finds that the variation between mice dominates this assay. These variance measures were used to examine the interplay between days, readings, and number of mice on power, the ability to detect change. If an experiment is underpowered, we cannot conclude whether failure to detect a biological difference arises from low power or lack of a distinct phenotype, hence the mice are subjected to testing without gain. Consequently, in confirmatory studies, a power analysis along with the 3Rs can provide justification to increase the number of mice used.

Recovery of motor deficit, cerebellar serotonin and lipid peroxidation levels in the cortex of injured rats

The sensorimotor cortex and the cerebellum are interconnected by the corticopontocerebellar (CPC) pathway and by neuronal groups such as the serotonergic system. Our aims were to determine the levels of cerebellar serotonin (5-HT) and lipid peroxidation (LP) after cortical iron injection and to analyze the motor function produced by the injury. Rats were divided into the following three groups: control, injured and recovering. Motor function was evaluated using the beam-walking test as an assessment of overall locomotor function and the footprint test as an assessment of gait. We also determined the levels of 5-HT and LP two and twenty days post-lesion. We found an increase in cerebellar 5-HT and a concomitant increase in LP in the pons and cerebellum of injured rats, which correlated with their motor deficits. Recovering rats showed normal 5-HT and LP levels. The increase of 5-HT in injured rats could be a result of serotonergic axonal injury after cortical iron injection. The LP and motor deficits could be due to impairments in neuronal connectivity affecting the corticospinal and CPC tracts and dysmetric stride could be indicative of an ataxic gait that involves the cerebellum.

Improved reporting of statistical design and analysis: guidelines, education, and editorial policies

A majority of original articles published in biomedical journals include some form of statistical analysis. Unfortunately, many of the articles contain errors in statistical design and/or analysis. These errors are worrisome, as the misuse of statistics jeopardizes the process of scientific discovery and the accumulation of scientific knowledge. To help avoid these errors and improve statistical reporting, four approaches are suggested: (1) development of guidelines for statistical reporting that could be adopted by all journals, (2) improvement in statistics curricula in biomedical research programs with an emphasis on hands-on teaching by biostatisticians, (3) expansion and enhancement of biomedical science curricula in statistics programs, and (4) increased participation of biostatisticians in the peer review process along with the adoption of more rigorous journal editorial policies regarding statistics. In this chapter, we provide an overview of these issues with emphasis to the field of molecular biology and highlight the need for continuing efforts on all fronts.

Dedicated mouse production and husbandry

The complexity of mammalian biology, in combination with the ability to manipulate the embryonic genome in mice, has provided specific challenges in terms of mouse breeding, analysis, and husbandry. From the initial planning stage of a project involving the generation of novel, genetically altered mice, it is important to consider a number of potential issues involving the successful establishment and propagation of a transgenic line.

Development of Rocket Electrophoresis Technique as an Analytical Tool in Preformulation Study of Tetanus Vaccine Formulation

Rocket Electrophoresis (RE) technique relies on the difference in charges of the antigen and antibodies at the selected pH. The present study involves optimization of RE run conditions for Tetanus Toxoid (TT). Agarose gel (1% w/v, 20 ml, pH 8.6), anti-TT IgG - 1 IU/ml, temperature 4-8 degrees C and run duration of 18 h was found to be optimum. Height of the rocket-shaped precipitate was proportional to TT concentration. The RE method was found to be linear in the concentration range of 2.5 to 30 Lf/mL. The method was validated and found to be accurate, precise, and reproducible when analyzed statistically using student's t-test. RE was used as an analytical method for analyzing TT content in plain and marketed formulations as well as for the preformulation study of vaccine formulation where formulation additives were tested for compatibility with TT. The optimized RE method has several advantages: it uses safe materials, is inexpensive, and easy to perform. RE results are less prone to operator's bias as compared to flocculation test and can be documented by taking photographs and scanned by densitometer; RE can be easily standardized for the required antigen concentration by changing antitoxin concentration. It can be used as a very effective tool for qualitative and quantitative analysis and in preformulation studies of antigens.

Comments on the sub-group reports of the EU Technical Expert Working Group on the revision of Directive 86/609/EEC on the protection of animals used for experimental and other scientific purposes

A critical analysis is presented of the reports produced by four Technical Expert Working Group Sub-groups (SGs) on Ethical Review, Cost-Benefit, Authorisation and Scope, which were published on the EC website (http://ec.europa.eu/environment/chemicals/lab_animals/ia_info_en.htm), as part of the European Commission (EC)s review of EU Directive 86/609 EEC. This is in addition to our official response to the internet consultation questionnaire, submitted to the Commission on behalf of FRAME. Whilst the respective SG reports were extensive and detailed, we have identified several shortcomings, and in particular, a frequent lack of consensus among the SG members, resulting in a lack of clear guidance for the EC on what the revised Directive should contain, with reference to a number of crucial issues. Such indecisiveness could lead to wide discrepancies in the approaches of the EC, the European Parliament and the EU Member States concerning many issues of importance to animal welfare and the implementation of alternatives to animal experiments. These concerns range from logistical issues, such as requirements for named officers in authorised establishments, and the recording and publishing of statistics on animal use, to ethical and scientific problems, including the use of non-human primates, local ethical review, and education and training on the essential link between the Three Rs concept and best scientific practice. In each case, the basis for our concerns is explained, and suggestions for improvements to be incorporated into the revised Directive are made, in the hope that the harmonisation of approaches to laboratory animal experimentation and the use of alternative methods in the Member States can be maximised.

Teaching simple experimental design to undergraduates: do your students understand the basics?

This article provides instructors with guidelines for teaching simple experimental design for the comparison of two treatment groups. Two designs with specific examples are discussed along with common misconceptions that undergraduate students typically bring to the experiment design process. Features of experiment design that maximize power and minimize the effects of interindividual variation, thus allowing reduction of sample sizes, are described. Classroom implementation that emphasizes student-centered learning is suggested, and thought questions, designed to help students discover and name the basic principles of simple experiment design for themselves, are included with an answer key.

The strong-inference protocol: not just for grant proposals

The strong-inference protocol puts into action the important concepts in Platt's often-assigned, classic paper on the strong-inference method (10). Yet, perhaps because students are frequently performing experiments with known outcomes, the protocols they write as undergraduates are usually little more than step-by-step instructions for performing the experiment. The strong-inference protocol, however, includes an explicit statement of possible experimental outcomes and the interpretation that would follow from each. This approach encourages thorough planning, enhances the efficiency of experimental designs, and increases the power of statistical analysis by explicitly stating a priori predictions as well as the statistical methods that will be used to test them. A sample protocol for an experiment investigating temperature-metabolism relations in chicken embryos is provided to illustrate the important components of the strong-inference protocol and to encourage instructors to incorporate this powerful research tool into undergraduate laboratory courses.

Pontine and cerebellar norepinephrine content in adult rats recovering from focal cortical injury

Norepinephrine (NE) plays an important role in motor recovery after brain damage. Most studies concerning NE activity have been performed in the cerebellum, while the role of the pons, the site where the norepinephrinergic locus coeruleus is located, has not yet been elucidated. For this work, we studied the changes in cerebellar and pontine NE content in sham-operated (n = 17), motor cortex injured (n = 6) and recovered rats (n = 12). Motor effects were assessed by means of footprint analysis and sensorimotor evaluation. It was found that after cortical brain damage, the stride length decreases while the stride angle increases after 6 h post-surgery, while the sensorimotor evaluation showed an increase in the motor deficit. Recovery was observed after 24 h. NE content increased in the pons after 6 h and returned to normal levels in recovered rats, with no significant changes observed in the cerebellum. Based on the functional remote inhibition, it is possible that NE exerts an autoinhibitory effect in the pons after motor cortical ablation. On the other hand, the absence of an effect in the cerebellum suggests that cerebellar NE activity related to damage and/or recovery is limited to discrete areas of the structure.

The Three Rs in the pharmaceutical industry: perspectives of scientists and regulators

Six drug regulatory reviewers and 11 pharmaceutical industry scientists were interviewed to explore their perspectives on the obstacles and opportunities for greater implementation of the Three Rs (replacement, reduction, refinement) in drug research and development. Participants generally supported the current level of animal use in the pharmaceutical industry and viewed in vitro methods as supporting, but not replacing, the use of animals. Obstacles to greater use of the Three Rs cited by participants included the lack of non-animal alternatives; requirements for statistical validity; reluctance by industry and regulators to depart from established patterns of animal use; the priority of commercial objectives ahead of the Three Rs; and concern that less animal testing could jeopardise human safety. Opportunities identified for the Three Rs included the development of better animal models including genetically modified (GM) animals; pursuit of more basic knowledge, notably drug action on gene expression; re-use of animals; greater use of pilot studies; using sufficient numbers of animals per test to avoid repeating inconclusive studies; regular review of animal data in regulatory requirements; and following the regulatory option of combining segments of reproductive toxicology studies into one study. In some areas, greater implementation of the Three Rs seemed well aligned with industry priorities, for example, phenotypic characterisation of GM animals and validation of alternative methods. In other areas, wider use of the Three Rs may require building consensus on areas of disagreement including the usefulness of death as an endpoint; the suitability of re-using animals; and whether GM animals and the use of pilot studies contribute to reduction.

The Three Rs: past, present and future

“Our story must begin with Charles Hume, for the whole of this grand enterprise began as a twinkle in his eye, which often twinkled” (Russell 1995). Fifty-one years ago, in 1954, besides important achievements in other fields of animal welfare, Hume and the Universities Federation for Animal Welfare (UFAW) had brought out the first edition of The UFAW Handbook on the Care and Management of Laboratory Animals, edited by Alastair Worden (Worden 1947), who was already preparing a greatly enlarged second edition with William Lane-Petter (Worden & Lane-Petter 1957). Hume had already contributed to the first edition of the Handbook an article on statistical analysis, which is clearly relevant to actual experimentation (Hume 1947); he now had the brilliant and totally original idea of starting a general study of humane technique in actual experimentation. The late Rex Burch and I were appointed to undertake this project; the moment Rex walked into my office I knew that here was not only the perfect colleague but also a lifelong friend, and I sadly miss him.