Microstructure of the corneal endothelial transition zone in different laboratory animals.

Purpose: To compare the microstructure of the corneal endothelial transition zone in different laboratory animals. Methods: Flat-mount corneas of rabbits, rats, and mice were stained with Alizarin Red S (ARS) and observed using scanning electron microscopy (SEM). The progenitor cell markers p75 neurotrophin receptor (p75NTR), SRY-box transcription factor 9 (SOX9), leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5), telomerase reverse transcriptase (TERT), and proliferation marker Ki-67 were examined in the flat-mounted corneas of three laboratory animals using immunofluorescence microscopy. Results: On flat mounts, proximity to the trabecular meshwork correlated with weaker ARS staining and greater polymorphism of endothelial cells in the transition zone in all animals. On SEM, distinct and smooth structures of the transition zone were negligibly detected in all animals. The endothelial cells in the transition zone had irregular shapes, with less dense, less wavy intercellular junctions, especially in murine corneas, exhibiting unique intercellular cystic spaces. In the transition zone of the rabbit cornea, progenitor cell markers p75NTR, SOX9, Lgr5, TERT, and proliferation marker Ki-67 were expressed, in contrast to those in other murine corneas. Conclusions: Although the transition zone was not identified clearly, irregular cell morphology and loss of cell-cell contact were observed in all animal corneal endothelial cells. The proliferative capacity and the presence of progenitor cells were confirmed in the transition zone, especially in the rabbit cornea.

Quantitative morphological analysis of age structural changes in prostate of experimental animals with ethanol poisoning.

OBJECTIVE: Aim: To find out the age remodeling of the structural components of the prostate gland at alcohol poisoning using quantitative morphological analysis. PATIENTS AND METHODS: Materials and Methods: The structure of the prostate gland of 4 white male rats groups were morphologically investigated. The 1 group included 30 control intact animals aged 8 months, the 2-nd group - 30 rats aged 24 months, the 3-rd group - 30 8-month-old animals with ethanol intoxication, and the 4-th group included 30 24-month-old rats with the specified simulated pathology. Ethanol intoxication was modeled by intragastric administration of 30% ethyl alcohol solution at a dose of 20 ml/kg once daily for 28 days. Rats were euthanized by bloodletting under general thiopental anesthesia 28 days after the beginning of the experiment. The area of glands, the height of glandular epithelial cells, the area of their nuclei and cytoplasm, the nuclear-cytoplasmic ratio in these cells and the stromal-parenchymal ratio in the organ were studied using light microscopy and were determined morphometrically. Morphometric parameters were processed statistically. RESULTS: Results: It was established that with age in the intact prostate of laboratory sexually mature white male rats, the area of glands, the height of glandular epitheliocytes, the area of their nuclei and cytoplasm, with the stability of nuclear-cytoplasmic ratios in the epithelial cells of the glands, significantly decreases, and the stromal-parenchymal ratio in the organ under study increases. Long-term ethanol poisoning leads to pronounced structural changes in the prostate, which is characterized by pronounced atrophy of the glandular epithelium, a decrease in the area of the glands, a decrease in the height of epithelial cells, a violation of nuclear-cytoplasmic relations in them, an increase in stromal-parenchymal ratio, and a prominent growth of the muscle-elastic stroma. The revealed structural changes of the studied components of the prostate dominated in 24-month-old experimental animals. CONCLUSION: Conclusions: Morphological analysis of the prostate gland established that morphometric and morphological changed significantly according to the age and were depend on the ethanol poisoning.

Immunoinformatics-guided recombinant polypeptide-based enzyme-linked immunosorbent assay for seromonitoring of laboratory animals for minute virus of mice and Kilham rat virus.

Subclinical infection of laboratory animals with one or more of several pathogens affects the results of experiments on animals. Monitoring the health of laboratory animals encompasses routine surveillance for pathogens, including several viruses. This study aimed to explore the development of an alternative assay to the existing ones for detecting infection of mice and rats with the parvoviruses minute virus of mice (MVM) and Kilham rat virus (KRV), respectively. Full-length VP2 and NS1 proteins of these parvoviruses, besides fragments containing multiple predicted epitopes stitched together, were studied for serological detection. The optimal dilution of full-length proteins and antigenic regions containing predicted epitopes for coating, test sera, and conjugate was determined using a checkerboard titration at each step. The assays were evaluated vis-à-vis commercially available ELISA kits. The results showed that an engineered fusion of fragments containing multiple predicted MVM VP2 and NS1 epitopes was better than either of the full-length proteins for detecting antibodies in 90% of the tested sera samples. For KRV ELISA, full-length VP2 was better compared to other individual recombinant protein fragments or combinations thereof for the detection of antibodies in sera. This report is the first description of an ELISA for KRV and an improved assay for MVM. Importantly, our assays could be exploited with small volumes of sera. The results also demonstrate the utility of immunoinformatics-driven polypeptide engineering in the development of diagnostic assays and the potential to develop better tests for monitoring the health status of laboratory animals.

SARS-CoV-2 inactivation in laboratory animal tissues with 4% formaldehyde or 5% glutaraldehyde for transfer to biosafety level 1 laboratories.

The SARS-CoV-2 pandemic required the immediate need to transfer inactivated tissue from biosafety level (BSL)-3 to BSL-1 areas to enable downstream analytical methods. No validated SARS-CoV-2 inactivation protocols were available for either formaldehyde (FA)-fixed or glutaraldehyde (GA)-fixed tissues. Therefore, representative tissue from ferrets and hamsters was spiked with 2.2 × 106 tissue culture infectious dose 50% per ml (TCID50/ml) SARS-CoV-2 or were obtained from mice experimentally infected with SARS-CoV-2. SARS-CoV-2 inactivation was demonstrated with 4% FA or 5% GA at room temperature for 72 hours by a titer reduction of up to 103.8 TCID50/ml in different animal tissues with a maximum protein content of 100 µg/mg and a thickness of up to 10 mm for FA and 8 mm for GA. Our protocols can be easily adapted for validating the inactivation of other pathogens to allow for the transfer of biological samples from BSL-3 areas to BSL-1 laboratories.

Neuroactive steroids and Parkinson's disease: Review of human and animal studies.

The greater prevalence and incidence of Parkinson's disease (PD) in men suggest a beneficial effect of sex hormones. Neuroactive steroids have neuroprotective activities thus offering interesting option for disease-modifying therapy for PD. Neuroactive steroids are also neuromodulators of neurotransmitter systems and may thus help to control PD symptoms and side effect of dopamine medication. Here, we review the effect on sex hormones (estrogen, androgen, progesterone and its metabolites) as well as androstenediol, pregnenolone and dehydroepiandrosterone) in human studies and in animal models of PD. The effect of neuroactive steroids is reviewed by considering sex and hormonal status to help identify specifically for women and men with PD what might be a preventive approach or a symptomatic treatment. PD is a complex disease and the pathogenesis likely involves multiple cellular processes. Thus it might be useful to target different cellular mechanisms that contribute to neuronal loss and neuroactive steroids provide therapeutics options as they have multiple mechanisms of action.

Age-Dependent Changes in the Effects of Androgens on Female Metabolic and Body Weight Regulation Systems in Humans and Laboratory Animals.

In recent years, the effects of androgens on metabolic and body weight regulation systems and their underlying mechanisms have been gradually revealed in females. In women and experimental animals of reproductive age, androgen excess can adversely affect metabolic functioning, appetite, and body weight regulation. In addition, excess androgens can increase the risk of metabolic disorders, such as obesity, insulin resistance, and diabetes. These unfavorable effects of androgens are induced by alterations in the actions of hypothalamic appetite-regulatory factors, reductions in energy expenditure, insulin resistance in skeletal muscle, and ß-cell dysfunction. Interestingly, these unfavorable effects of androgens on metabolic and body-weight regulation systems are neither observed nor evident in ovariectomized animals and post-menopausal women, indicating that the adverse effects of androgens might be dependent on the estrogen milieu. Recent findings may provide novel sex- and age-specific strategies for treating metabolic diseases.

Biodistribution of Mesenchymal Stromal Cells Labeled with [89Zr]Zr-Oxine in Local Radiation Injuries in Laboratory Animals.

BACKGROUND: Tracking the migration pathways of living cells after their introduction into a patient's body is a topical issue in the field of cell therapy. Questions related to studying the possibility of long-term intravital biodistribution of mesenchymal stromal cells in the body currently remain open. METHODS: Forty-nine laboratory animals were used in the study. Modeling of local radiation injuries was carried out, and the dynamics of the distribution of mesenchymal stromal cells labeled with [89Zr]Zr-oxine in the rat body were studied. RESULTS: the obtained results of the labelled cell distribution allow us to assume that this procedure could be useful for visualization of local radiation injury using positron emission tomography. However, further research is needed to confirm this assumption. CONCLUSIONS: intravenous injection leads to the initial accumulation of cells in the lungs and their subsequent redistribution to the liver, spleen, and kidneys. When locally injected into tissues, mesenchymal stromal cells are not distributed systemically in significant quantities.

Pharmacokinetics of Extended-release Buprenorphine in Mongolian Gerbils (Meriones unguiculatus).

Both the Guide for the Care and Use of Laboratory Animals and the Animal Welfare Act and Regulations require animals in research to receive adequate analgesia unless an exception can be scientifically justified and IACUC approved. Extended- release buprenorphine (BUP-XR) is a pharmaceutical-grade formulation that is FDA-indexed for use in mice and rats. However, this new formulation has not been evaluated in adult Mongolian gerbils (Meriones unguiculatus). Our goal was to determine whether the extrapolated dose (1 mg/kg SC) would achieve plasma buprenorphine concentrations above the murine therapeutic threshold (> 1.0 ng/mL) in male and female gerbils. We hypothesized that BUP-XR administered at 1 mg/kg would achieve the murine therapeutic threshold in both male and female gerbils until at least 48 h after injection. Gerbils received one injection of BUP-XR (1 mg/kg SC) and underwent 4 serial blood collections (0.5, 1, 2, and 4, or 0.5, 24, 48, and 72 h after injection). The average plasma buprenorphine concentrations were above 1 ng/mL within 30 min of administration for both males and females. Plasma buprenorphine concentrations remained above 1.0 ng/mL for 48 h after administration. In males, plasma buprenorphine concentrations were significantly higher at 1 h after injection as compared with females; no other significant differences were observed between sexes. Mild to moderate injection-site granulomas were observed in five of nine gerbils, presumably due to the lipid matrix of the BUP-XR formulation. Our findings demonstrate that a single BUP-XR dose (1 mg/kg SC) achieves plasma buprenorphine levels that remain above the murine therapeutic threshold of 1.0 ng/mL for up to 48 h in both sexes.

Establishing a health-based recommended occupational exposure limit for isoflurane using experimental animal data: a systematic review protocol.

BACKGROUND: Isoflurane is used as an inhalation anesthetic in medical, paramedical, and veterinary practice. Epidemiological studies suggest an increased risk of miscarriages and malformations at birth related to maternal exposure to isoflurane and other inhalation anesthetics. However, these studies cannot be used to derive an occupational exposure level (OEL), because exposure was not determined quantitatively and other risk factors such as co-exposures to other inhalation anesthetics and other work-related factors may also have contributed to the observed adverse outcomes. The aim of this systematic review project is to assess all available evidence on the effects of isoflurane in studies of controlled exposures in laboratory animals to derive a health-based recommended OEL. METHODS: A comprehensive search strategy was developed to retrieve all animal studies addressing isoflurane exposure from PubMed, EMBASE, and Web of Science. Title-abstract screening will be performed by machine learning, and full-text screening by one reviewer. Discrepancies will be resolved by discussion. We will include primary research in healthy, sexually mature (non human) vertebrates of single exposure to isoflurane. Studies describing combined exposure and treatments with > = 1 vol% isoflurane will be excluded. Subsequently, details regarding study identification, study design, animal model, and intervention will be summarized. All relevant exposure characteristics and outcomes will be extracted. The risk of bias will be assessed by two independent reviewers using an adapted version of the SYRCLE's risk of bias tool and an addition of the OHAT tool. For all outcomes for which dose-response curves can be derived, the benchmark dose (BMD) approach will be used to establish a point of departure for deriving a recommended health-based recommended OEL for 8 h (workshift exposure) and for 15 min (short-term exposure). DISCUSSION: Included studies should be sufficiently sensitive to detect the adverse health outcomes of interest. Uncertainties in the extrapolation from animals to humans will be addressed using assessment factor. These factors are justified in accordance with current practice in chemical risk assessment. A panel of experts will be involved to reach consensus decisions regarding significant steps in this project, such as determination of the critical effects and how to extrapolate from animals to humans. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022308978.

Microbial experience through housing in a farmyard-type environment alters intestinal barrier properties in mouse colons.

To close the gap between ultra-hygienic research mouse models and the much more environmentally exposed conditions of humans, we have established a system where laboratory mice are raised under a full set of environmental factors present in a naturalistic, farmyard-type habitat-a process we have called feralization. In previous studies we have shown that feralized (Fer) mice were protected against colorectal cancer when compared to conventionally reared laboratory mice (Lab). However, the protective mechanisms remain to be elucidated. Disruption of the protective intestinal barrier is an acknowledged player in colorectal carcinogenesis, and in the current study we assessed colonic mucosal barrier properties in healthy, feralized C57BL/6JRj male mice. While we found no effect of feralization on mucus layer properties, higher expression of genes encoding the mucus components Fcgbp and Clca1 still suggested mucus enforcement due to feralization. Genes encoding other proteins known to be involved in bacterial defense (Itln1, Ang1, Retnlb) and inflammatory mechanisms (Zbp1, Gsdmc2) were also higher expressed in feralized mice, further suggesting that the Fer mice have an altered intestinal mucosal barrier. These findings demonstrate that microbial experience conferred by housing in a farmyard-type environment alters the intestinal barrier properties in mice possibly leading to a more robust protection against disease. Future studies to unravel regulatory roles of feralization on intestinal barrier should aim to conduct proteomic analyses and in vivo performance of the feralized mice intestinal barrier.

The effect of green synthesis of TiO2 nanoparticles/collagen/HA scaffold in bone regeneration: As an animal study.

BACKGROUND: The bone defects cannot heal by themselves when their range exceeds the critical size defect (CSD). In clinical treatment, significant bone defects are often caused by trauma, developmental deformity, tumour resection and infection. OBJECTIVES: The purpose of this study was to investigate the effect of green synthesis of TiO2 from propolis extract/collagen/HA (Hydroxyapatite) scaffolds on bone regeneration in rats. METHODS: Water uptake, biodegradability, porosity and biodegradation of the scaffolds were evaluated after they were synthesised using freeze-dry method. Cell viability by MTT assay was then evaluated. During the 4, 8 and 12 weeks following the scaffold implantation, the bone regeneration was evaluated using macroscopic and microscopic tests to determine the effectiveness of green synthesis of TiO2 from propolis extract/collagen/HA scaffolds. RESULTS: Compared to the HA/Coll scaffold, ProTiO2 /HA/Coll scaffold was reduced porosity, water absorption and degradability porosity. Based on in vitro tests, both synthetic scaffolds induced cell growth and were less toxic and stimulated cell growth. Based on histopathological testing, the ProTiO2 /HA/Coll scaffolds formed high levels of bone during 12 weeks in comparison with HA/Coll and control group. CONCLUSIONS: ProTiO2 /HA/Coll composite can be used in regenerative medicine, bone fillers and scaffolds. As a result, this research suggests that ProTiO2 /HA/Coll composites could be promising candidates for bone regeneration.

The malaria blood stage antigen PfCyRPA formulated with the TLR-4 agonist adjuvant GLA-SE elicits parasite growth inhibitory antibodies in experimental animals.

BACKGROUND: Plasmodium falciparum cysteine-rich protective antigen (PfCyRPA) is an invasion complex protein essential for erythrocyte invasion. In contrast to several previously clinically tested merozoite vaccine candidate antigens, PfCyRPA is not polymorphic, making it a promising candidate antigen for blood stage vaccine development. METHODS: Mice and rabbits were immunized with vaccine formulations of recombinantly expressed PfCyRPA adjuvanted either with the glucopyranosyl lipid A (GLA) containing adjuvants GLA-LSQ, GLA-SE, GLA-Alum or with Nanoalum. ELISA and indirect immunofluorescence assays (IFA) were used to analyse elicited IgG titers and the P. falciparum growth inhibitory activity was determined with a standardized in vitro [3H]-hypoxanthine incorporation assay. RESULTS: In the mouse experiments, the GLA adjuvanted formulations were superior to the Nanoalum formulation with respect to antibody titer development, IFA sero-conversion rates and in vitro parasite growth-inhibitory activity. In rabbits, the highest titers of parasite growth inhibitory antibodies were obtained with the GLA-SE formulation. Comparable mean ELISA IgG endpoint titers were reached in rabbits after three immunizations with GLA-SE adjuvanted PfCyRPA doses of 5, 25 and 100 µg, but with 100 µg of antigen, only two immunizations were required to reach this titer. CONCLUSION: PfCyRPA formulated with the human-compatible adjuvant GLA-SE represents an attractive vaccine candidate for early clinical testing in a controlled P. falciparum blood stage challenge trial.

Enhancing intestinal anastomotic healing using butyrate: Systematic review and meta-analysis of experimental animal studies.

BACKGROUND: Despite advancements in surgical technique and perioperative care, intestinal anastomoses still have a 10-15 per cent risk of leakage, which results in considerable morbidity and/or mortality. Recent animal studies have suggested that administration of butyrate to the anastomotic site results in enhanced anastomotic strength, which may prevent leakage. This systematic review and meta-analysis summarises current evidence concerning the effect of butyrate administration on anastomotic healing and will form a scientific basis for the development of new research into this subject. METHODS: Animal studies on the effect of butyrate-based interventions in models of intestinal anastomotic healing were systematically retrieved from online databases. Bibliographical data, study characteristics and outcome data were extracted, and internal validity of the studies was assessed. Outcomes studied through meta-analysis concerned: anastomotic strength, anastomotic leakage, collagen metabolism and general histologic parameters of wound healing. RESULTS: A comprehensive search and selection identified 19 relevant studies containing 41 individual comparisons. Design and conduct of most experiments were poorly reported resulting in an unclear risk of bias. Meta-analyses showed that butyrate administration significantly increases anastomotic strength (SMD 1.24, 0.88 to 1.61), collagen synthesis (SMD 1.44, 0.72 to 2.15) and collagen maturation, making anastomoses less prone to leakage in the early postoperative period (OR 0.37, 0.15 to 0.93). CONCLUSION: This systematic review and meta-analysis shows that there is potential ground to investigate the use of butyrate in clinical trials to prevent anastomotic leakage in intestinal surgery. However, more research is necessary to define the best application form, dosage and administration route.

Anti-Tumor Efficacy of Photodynamic Therapy of Solid Tumors in Laboratory Animals with Guanidine and Biguanidine Derivatives of Chlorine e6.

We evaluated antitumor efficacy of photodynamic therapy of murine Ehrlich carcinoma and rat sarcoma M-1 with new photosensitizers 131-N-(4-aminobutyl)amydo chlorine e6 (1), 132-(5-guanidylbutanamido)-chlorine e6 (2), and 132-(5-biguanidylbutanamido)-chlorine e6 (3). The inhibiting effect of the photodynamic therapy was evaluated by the following parameters: tumor growth inhibition, complete regression of the tumors, and absolute growth rate of the tumor nodes in animals with the continued neoplasia growth. The criterion of cure was the absence of tumors up to 90 days after the therapy. It is shown that the studied photosensitizers have high antitumor activity in the photodynamic therapy of the Ehrlich carcinoma and sarcoma M-1.

La hipertensión arterial en animales de laboratorio / High blood pressure in experimental animals

Las Ciencias Médicas y Biológicas requieren, prioritariamente, que la investigación y la experimentación sean desarrolladas sobre organismos completos (los modelos animales). Su utilización ha permitido desarrollar innumerables ensayos preclínicos para evaluar los mecanismos patógenos y terapéuticos de diversas enfermedades, así como el estudio de las causas, naturaleza y cura de múltiples desórdenes de la salud humana. En este trabajo se muestra una panorámica general de los biomodelos de hipertensión arterial donde se describen: conceptos, características, origen, importancia, utilidad y procedimientos experimentales durante su fase de inducción. También se pondera la justificación de los biomodelos empleados en los estudios preclínicos de esta enfermedad. De igual forma, se describen los antecedentes para medir las alteraciones, las técnicas y los métodos directos e indirectos de medición de la presión arterial, la cual fue provocada experimentalmente en los animales de laboratorio para realizar los estudios de hipertensión humana.

Medical and biological sciences require, as a priority, that research and experimentation be carried out on complete organisms (animal models). Its use has allowed the development of innumerable preclinical tests to evaluate pathogenic and therapeutic mechanisms of various diseases, as well as to study the causes, nature and cure of multiple human health disorders. In this work, we show a general overview of arterial hypertension biomodels where concepts, characteristics, origin, importance, utility and experimental procedures during their induction phase are described. The justification of the biomodels used in preclinical studies of this disease is also considered. Antecedents are also described to measure alterations, techniques and direct and indirect methods of measurement of arterial pressure, which was provoked experimentally in the laboratory animals to carry out the studies of human hypertension.

When less is more: Experimental Bishop-Koop technique for reduction in the use of laboratory animals for intestinal pathophysiological studies.

The use of animals to gain knowledge and understanding of diseases needs to be reduced and refined. In the field of intestinal research, because of the complexity of the gut immune system, living models testing is mandatory. Based on the 3Rs (replacement, reduction and refinement) principles, we aimed to developed and apply the derived-intestinal surgical procedure described by Bishop and Koop (BK) in rats to refine experimental gastrointestinal procedures and reduce the number of animals used for research employing two models of intestinal inflammation: intestinal ischemia-reperfusion injury and chemical-induced colitis. Our results show the feasibility of the application of the BK technique in rodents, with good success after surgical procedure in both small and large intestine (100% survival, clinical recovery and weight regain). A considerable reduction in the use of the number of rats in both intestinal inflammation models (80% in case of intestinal ischemia-reperfusion damage and 66.6% in chemical-induced colitis in our experimental design) was achieved. Compared with conventional experimental models described by various research groups, we report excellent reproducibility of intestinal damage and functionality, survival rate and clinical status of the animals when BK is applied.

Effects of Flash Radiotherapy on Blood Lymphocytes in Humans and Small Laboratory Animals.

A mathematical model, which describes the level of surviving lymphocytes in the blood after ultra-high (FLASH) and lower dose rates of partial-body irradiation, is developed. The model is represented by simple analytic formulae that involve a few parameters, namely, physiologic parameters (characteristics of the blood flow through the blood circulatory system and its irradiated part), a biophysical parameter (a characteristic of the blood lymphocytes radiosensitivity), and the physical parameters (characteristics of irradiation). The model predicts that the level of surviving blood lymphocytes increases as the dose rate increases and approaches the limiting level of (1 - vR), where vR is the fraction of the blood volume in the irradiated part of the blood circulatory system. The model also predicts that the level of surviving blood lymphocytes after the same exposure is higher for lower vR. It is found that FLASH irradiation in humans with doses of 10 to 40 Gy and with exposure times significantly less (<1 s) than the blood circulation time (∼60 s) leads to the maximal blood lymphocyte sparing. Simple formula, which determines effective dose rates for optimal blood lymphocyte sparing, is derived in the framework of the developed model. For the dose range specified above, the obtained modeling prediction of the range of effective dose rates for optimal blood lymphocyte sparing in humans (namely, N ≥40 Gy/s) coincides with the dose rate range in FLASH radiation therapy. It is revealed that the respective effective dose rates for mice are higher than those for humans (for the same dose range) due to the shorter blood circulation time in mice than in humans. Proceeding from the findings obtained in this paper, a hypothesis elucidating the mechanisms of the abscopal effect of FLASH radiation therapy (namely, an antitumor response on metastases located outside of irradiated part of a body) is proposed.

Method of measuring effects of study procedures in single and pair housed New Zealand White rabbits (Oryctolagus cuniculus).

Social housing of laboratory rabbits is encouraged and thought to improve animal welfare due to the social nature of this species. However, there is limited published information comparing the physiologic and cardiovascular (CV) effects of paired and single housed adult female rabbits in commonly used laboratory caging. This study describes measurement of heart rate, systolic blood pressure, activity level, body temperature and pairing methods in four female New Zealand White rabbits that were previously implanted with M10 cardiovascular telemetry devices. Data was collected in single housed rabbits having no history of social housing while they were undisturbed in the home cage, during restraint, intramuscular injections and intravenous blood collection. The same animals were then placed in compatible pairs and housed in conventional Allentown caging. As expected, we found increased activity in paired rabbits but no significant differences in body temperatures, and CV parameters in single and paired rabbits undergoing the same procedures. These data suggest that paired rabbits can be used for safety pharmacology studies with minimal impact to data, while supporting improved animal welfare.

Human dentin materials for minimally invasive bone regeneration: Animal studies and clinical cases.

OBJECTIVES: Bone, platelet concentrate, and tooth-derived dentin/cementum have been used as autologous materials in regenerative medicine Dentin materials were first recycled in 2002 for bone regeneration in humans, although bone autografts were noted in the 19th century, and auto-platelet concentrates were developed in 1998. Dentin/cementum-based material therapy has been applied as an innovative technique for minimally invasive bone surgery, while bone autografts are associated with donor site morbidity. METHODS: In October 2021, PubMed, Google Scholar, Scopus, and the Cochrane Library databases from 1980 to 2020 were screened. RESULTS: The demineralized dentin/cementum matrix (DDM) had better performance in bone induction and bone regeneration than mineralized dentin. CONCLUSIONS: Unlike cell culture therapy, DDM is a matrix-based therapy that includes growth factors. A matrix-based system is a realistic and acceptable treatment, even in developing countries. The aim of this review was to summarize the evidence related to both animal studies and human clinical cases using human dentin materials with a patch of cementum, especially DDM.

The Current Status and Work of Three Rs Centres and Platforms in Europe.

The adoption of Directive 2010/63/EU on the protection of animals used for scientific purposes has given a major push to the formation of Three Rs initiatives in the form of centres and platforms. These centres and platforms are dedicated to the so-called Three Rs, which are the Replacement, Reduction and Refinement of animal use in experiments. ATLA's 50th Anniversary year has seen the publication of two articles on European Three Rs centres and platforms. The first of these was about the progressive rise in their numbers and about their founding history; this second part focuses on their current status and activities. This article takes a closer look at their financial and organisational structures, describes their Three Rs focus and core activities (dissemination, education, implementation, scientific quality/translatability, ethics), and presents their areas of responsibility and projects in detail. This overview of the work and diverse structures of the Three Rs centres and platforms is not only intended to bring them closer to the reader, but also to provide role models and show examples of how such Three Rs centres and platforms could be made sustainable. The Three Rs centres and platforms are very important focal points and play an immense role as facilitators of Directive 2010/63/EU 'on the ground' in their respective countries. They are also invaluable for the wide dissemination of information and for promoting the implementation of the Three Rs in general.