Swollen Ampulla as an Indicator of Successful Pregnancy in B6C3F1 Recipient Mice used for Assisted Reproduction.

In vitro fertilization (IVF), embryo cryopreservation, and embryo transfer (ET) are assisted reproductive technologies (ARTs) that are used extensively for the maintenance of mouse models in animal research. Inbred mouse strains with different genetic backgrounds vary in their reproductive performance. Cryopreservation can affect embryo quality and viability, and the genetic background of ET recipients can influence the ET result. In this retrospective study, we analyzed the out- comes of ETs performed in our facility during the last 6 y. We found that B6C3F1 mice with swollen ampullae show almost 3-fold higher pregnancy rates than mice with nonswollen ampullae when either freshly isolated or frozen-thawed embryos are implanted. Implantation of freshly collected embryos in recipients with swollen ampullae led to significantly higher pregnancy rates in comparison to implantation of frozen-thawed embryos, regardless of whether the latter were fertilized in vivo or in vitro. Moreover, we found a significant effect of genetic background on the birth rate; C57BL/6J mice and mice with a mixed genetic background had 34% higher birth rates than did C57BL/6N mice. Within the C57BL/6J group, the birth rates were significantly higher when using fresh in vivo-fertilized embryos, and cryopreservation negatively affected both in vivo- and in vitro-fertilized embryos. The success rate of obtaining one living pup was not significantly different between frozen-thawed and fresh embryos. Overall, a swollen ampulla is a strong indicator for a successful pregnancy, together with the embryo manipulation and genetic background. A better understanding of the factors that affect the reproductive outcome might lead to optimization of the ART protocols and contribute to a reduction in the number of mice used for these procedures.

Comparison of compositional MRI techniques to quantify the regenerative potential of articular cartilage: a preclinical minipig model after osteochondral defect treatments with autologous mesenchymal stromal cells and unseeded scaffolds.

Background: The field of orthopedics seeks effective, safer methods for evaluating articular cartilage regeneration. Despite various treatment innovations, non-invasive, contrast-free full quantitative assessments of hyaline articular cartilage's regenerative potential using compositional magnetic resonance (MR) sequences remain challenging. In this context, our aim was to investigate the effectiveness of different MR sequences for quantitative assessment of cartilage and to compare them with the current gold standard delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC) measurements. Methods: We employed ex vivo imaging in a preclinical minipig model to assess knee cartilage regeneration. Standardized osteochondral defects were drilled in the proximal femur of the specimens (n=14), which were divided into four groups. Porcine collagen scaffolds seeded with autologous adipose-derived stromal cells (ASC), autologous bone marrow stromal cells (BMSC), and unseeded scaffolds (US) were implanted in femoral defects. Furthermore, there was a defect group which received no treatment. After 6 months, the specimens were examined using different compositional MR methods, including the gold standard dGEMRIC as well as T1, T2, T2*, and T1ρ techniques. The statistical evaluation involved comparing the defect region with the uninjured tibia and femur cartilage layers and all measurements were performed on a clinical 3T MR Scanner. Results: In the untreated defect group, we observed significant differences in the defect region, with dGEMRIC values significantly lower (404.86±64.2 ms, P=0.018) and T2 times significantly higher (44.24±2.75 ms, P<0.001). Contrastingly, in all three treatment groups (ASC, BMSC, US), there were no significant differences among the three regions in the dGEMRIC sequence, suggesting successful cartilage regeneration. However, T1, T2*, and T1ρ sequences failed to detect such differences, highlighting their lower sensitivity for cartilage regeneration. Conclusions: As expected, dGEMRIC is well suited for monitoring cartilage regeneration. Interestingly, T2 imaging also proved to be a reliable cartilage imaging technique and thus offers a contrast agent-free alternative to the former gold standard for subsequent in vivo studies investigating the cartilage regeneration potential of different treatment modalities.

Plate-associated localized osteitis in mini-pig by biofilm-forming Methicillin-resistant Staphylococcus aureus (MRSA): establishment of a novel experimental model.

PURPOSE: The increasing number of implant-associated infections during trauma and orthopedic surgery caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance of conventional antibiotics requires new therapeutic strategies. One possibility could be testing for different therapeutic strategies with differently coated plates. Therefore, a clinically realistic model is required. The pig offers the best comparability to the human situation, thus it was chosen for this model. The present study characterizes a novel model of a standardized low-grade acute osteitis with bone defect in the femur in mini-pigs, which is stabilized by a titanium locking plate to enable further studies with various coatings. METHODS: A bone defect was performed on the femur of 7 Aachen mini-pigs and infected with Methicillin-resistant S. aureus (MRSA ATCC 33592). The defect zone was stabilized with a titanium plate. After 14 days, a plate change, wound debridement and lavage were performed. Finally, after 42 days, the animals were lavaged and debrided again, followed by euthanasia. The fracture healing was evaluated radiologically and histologically. RESULTS: A local osteitis with radiologically visible lysis of the bone could be established. The unchanged high Colony-forming Units (CFU) in lavage, the significant differences in Interleukin (IL)-6 in blood compared to lavage and the lack of increase in Alkaline Phosphates (ALP) in serum over the entire observation period show the constant local infection. CONCLUSION: The study shows the successful induction of local osteitis with lysis of the bone and the lack of enzymatic activity to mineralize the bone. Therefore, this standardized mini-pig model can be used in further clinical studies, to investigate various coated implants, bone healing, biofilm formation and immune response in implant-associated osteitis.

Micro-angiogenic patterns around orthodontic implants migrating in bone: A micro-CT study in the rat tail model.

AIM: Recent studies revealed that implants can migrate in bone when subjected to continuous loading. Since this process is suspected to be accompanied by bone remodelling, which requires blood vessel formation, the present work aimed at assessing the micro-angiogenic patterns around migrating implants. MATERIALS AND METHODS: In 16 rats, two customized implants were placed in a single tail vertebra and connected with contraction springs (forces: 0 N, 0.5 N, 1.0 N, 1.5 N). After 2 or 8 weeks of loading, the animals were scanned by micro-CT before and after vasculature perfusion with a silicone rubber. Vessels were segmented by subtraction of the two micro-CT scans. Vessel thickness (V.Th), vessel volume per total volume (VV/TV), and vascular spacing (V.Sp) were assessed in a peri-implant volume of interest (VOI) around each implant. RESULTS: At 2 weeks of loading, force magnitude was significantly associated with VV/TV and V.Th values (χ2  = 10.942, p < .001 and χ2  = 6.028, p = .010, respectively). No significant differences were observed after 8 weeks of loading. CONCLUSIONS: Within the limitations of an animal study, peri-implant vessel thickness and density were associated with force magnitude in the early loading phase, whereas effects diminished after 8 weeks of loading.

Rodentibacter haemolyticus sp. nov. isolated from laboratory rodents.

Nine strains of a Rodentibacter-related bacterium were isolated over a period of 38 years from a laboratory mouse (Mus musculus), seven laboratory rats (Rattus norvegicus) and a Syrian hamster (Mesocricetus auratus) in Düsseldorf and Heidelberg, Germany. The isolates are genotypically and phenotypically distinct from all previously described Rodentibacter species. Sequence analysis of 16S rRNA and rpoB gene sequences placed the isolates as a novel lineage within the genus Rodentibacter. In addition to the single-gene analysis, the whole genome sequence of the strain 1625/19T revealed distinct genome-to-genome distance values to the other Rodentibacter species. The genomic DNA G+C content of strain 1625/19T was 40.8 mol% within the range of Rodentibacter. At least six phenotypic characteristics separate the new isolates from the other Rodentibacter species, with Rodentibacter heylii being the most closely related. In contrast to the latter, the new strains display ß-haemolysis and are ß-glucuronidase, d-mannitol and sorbitol positive, but fail to produce lysine decarboxylase and trehalose. The genotypic and phenotypic differences between the novel strains and the other closely related strains of the genus Rodentibacter indicate that they represent a novel species within the genus Rodentibacter, family Pasteurellaceae, for which the name Rodentibacter haemolyticus sp. nov. is proposed. The type strain 1625/19T, (=DSM 111151T=CCM 9081T), was isolated in 2019 from the nose of a laboratory mouse (Mus musculus) in Düsseldorf, Germany.

Does a Red House Affect Rhythms in Mice with a Corrupted Circadian System?

The circadian rhythms of body functions in mammals are controlled by the circadian system. The suprachiasmatic nucleus (SCN) in the hypothalamus orchestrates subordinate oscillators. Time information is conveyed from the retina to the SCN to coordinate an organism's physiology and behavior with the light/dark cycle. At the cellular level, molecular clockwork composed of interlocked transcriptional/translational feedback loops of clock genes drives rhythmic gene expression. Mice with targeted deletion of the essential clock gene Bmal1 (Bmal1-/-) have an impaired light input pathway into the circadian system and show a loss of circadian rhythms. The red house (RH) is an animal welfare measure widely used for rodents as a hiding place. Red plastic provides light at a low irradiance and long wavelength-conditions which affect the circadian system. It is not known yet whether the RH affects rhythmic behavior in mice with a corrupted circadian system. Here, we analyzed whether the RH affects spontaneous locomotor activity in Bmal1-/- mice under standard laboratory light conditions. In addition, mPER1- and p-ERK-immunoreactions, as markers for rhythmic SCN neuronal activity, and day/night plasma corticosterone levels were evaluated. Our findings indicate that application of the RH to Bmal1-/- abolishes rhythmic locomotor behavior and dampens rhythmic SCN neuronal activity. However, RH had no effect on the day/night difference in corticosterone levels.

Differentiation among the most important Rodentibacter species by multiplex PCR assays targeting the ITSile+ala sequences of the rRNA operons.

Screening for the Rodentibacter species is part of the microbiologic quality assurance programs of laboratory rodents all over the world. Nevertheless, currently there are no PCR amplification techniques available for the diagnostic of R. ratti, R. heidelbergensis and of a Rodentibacter related ß-haemolytic taxon. The aim of this study was to utilize the differences in the sequence of the Internal Transcribed Spacer (ITS) regions of R. pneumotropicus, R. heylii, R. ratti, R. heidelbergensis and of the ß-haemolytic Rodentibacter taxon for the design of specific PCR assays for these species. The ITSile+ala sequence variations allowed the design of specific forward and reverse primers for each species included, that could be combined in different multiplex assays. The performance characteristics specificity and sensitivity registered for each primer pair against a diverse collection of Pasteurellaceae isolated from rats and mice and of further non-Pasteurellaceae strains was 100% for all five Rodentibacter species included. In addition, the PCR assays displayed high limits of detection and could be successfully used for detection of Rodentibacter spp. DNA in clinical swabs of laboratory mice and rats. Overall, the assays described here represent the first PCRs able to diagnose R. ratti, R. heidelbergensis and the ß-haemolytic Rodentibacter taxon, whose diagnostic to species level could further facilitate better understanding of their geographic distribution, prevalence, and biology in the future.

Differentiation Among Rodentibacter Species Based on 16S-23S rRNA Internal Transcribed Spacer Analysis.

The internal transcribed spacer (ITS) regions of Rodentibacter pneumotropicus, R. heylii, R. rarus, R. ratti, and R. heidelbergensis and of a Rodentibacter- related ß-hemolytic Pasteurellaceae taxon isolated from laboratory rodents were studied for their feasibility to discriminate among these species. The 6 species analyzed showed species-specific ITS patterns that were shared by the type strains and clinical isolates and that allowed their identification. Nevertheless, differentiating between the ITS band patterns of R. pneumotropicus and R. ratti is visually challenging. In all species tested, sequence analysis of the ITS fragments revealed a larger ITSile+ala, which contained the genes for tRNAIle(GAU) and tRNA Ala(UGC), and a smaller ITSglu with the tRNAGlu(UUC) gene. The ITS sequences varied among the 6 species evaluated, displaying identity levels ranging from 62% to 86% for ITSile+ala and 68% to 90% for ITSglu. Overall, ITS amplification proved to be a reliable method to differentiate among these important Pasteurellaceae species of laboratory rodents. Moreover, the ITS sequence variations recorded here might facilitate the design of probes for specific identification of these species. The ability to diagnose these organisms to the species level could increase our understanding of their clinical significance.

Chronic stable heart failure model in ovine species.

Establishing a chronic heart failure (HF) model is challenging, particularly in the ovine model. The aim of this study was to establish a reproducible model of HF in an ovine model. Seventeen sheep were operated using the left thoracotomy approach. Chronic HF was induced through ligation of the diagonal and marginal branches only. Perioperative hemodynamic and echocardiographic parameters were compared. A total of (3 ± 1) coronary ligations were used. Thirteen animals survived the procedure and were followed up for (15 ± 5) days. The mean arterial pressure, heart rate (HR), mean pulmonary artery pressure (mPAP), central venous pressure, and cardiac output at baseline and prior to animal sacrifice was (75 ± 14 mmHg) and (68 ± 16 mmHg) P = .261; (72 ± 9 bpm), (100 ± 28 bpm) P = .01; (15 ± 4 mmHg) and (18 ± 5 mmHg) P = .034; (10 ± 6 mmHg) and (8 ± 4 mmHg) P = .326; (3.4 ± 1 L/min) and (3.9 ± 1 L/min) P = .286, respectively. The LVEF at baseline and prior to animal sacrifice was (63 ± 13%) and (43 ± 6%) P = .012. Twelve surviving animals were supported with LVAD in a follow-up procedure. Chronic stable HF in sheep was successively established. Clinical symptoms and drastic increase in the mPAP and HR as well as echo findings were the most sensitive parameters of HF. This reproducible ovine model has proven to be highly promising for research regarding HF.

Impact of tricuspid valve insufficiency on the performance of left ventricular assist devices.

Objective: To evaluate the impact of severe tricuspid valve insufficiency (TVI) at the time of left ventricular assist device (LVAD) implantation on the hemodynamic and LVAD parameters in an acute ovine model. Methods: Stable heart failure (HF) was induced in 10 ovines through the application of 3 ± 1 coronary ligations. Once stable HF was obtained (after 15 ± 5 days), the animals were supported with an LVAD. Hemodynamic data and pump parameters were obtained and compared in 2 settings; first with LVAD in place after weaning from the cardiopulmonary bypass machine (no TVI condition) and second following the induction of severe TVI through resection of the tricuspid valve (TVI condition). Results: There were no statistically significant differences in the hemodynamic and pump parameters between TVI condition and no TVI conditions except for lower cardiac output in the TVI condition (2 [1.38-2.8] L/min vs 3.2 [1.55-3.7] L/min, P = .027) and the expected greater central venous pressure in the TVI condition (26 [24-31] mm Hg vs 15 [13-25] mm Hg, P = .020). A median pump flow of 2.8 (2.45-3.75) L/min versus 2.9 (2.75-3.8) L/min in the TVI condition and no TVI condition was documented (P = .160). Conclusions: Results from this acute animal study suggest that severe TVI in HF with preserved right ventricular function does not have significant impact on the LVAD pump parameters. The observed reduction in cardiac output may warrant further investigations, especially under loading conditions.

Human iPSC-derived iMSCs improve bone regeneration in mini-pigs.

Autologous bone marrow concentrate (BMC) and mesenchymal stem cells (MSCs) have beneficial effects on the healing of bone defects. To address the shortcomings associated with the use of primary MSCs, induced pluripotent stem cell (iPSC)-derived MSCs (iMSCs) have been proposed as an alternative. The aim of this study was to investigate the bone regeneration potential of human iMSCs combined with calcium phosphate granules (CPG) in critical-size defects in the proximal tibias of mini-pigs in the early phase of bone healing compared to that of a previously reported autograft treatment and treatment with a composite made of either a combination of autologous BMC and CPG or CPG alone. iMSCs were derived from iPSCs originating from human fetal foreskin fibroblasts (HFFs). They were able to differentiate into osteoblasts in vitro, express a plethora of bone morphogenic proteins (BMPs) and secrete paracrine signaling-associated cytokines such as PDGF-AA and osteopontin. Radiologically and histomorphometrically, HFF-iMSC + CPG transplantation resulted in significantly better osseous consolidation than the transplantation of CPG alone and produced no significantly different outcomes compared to the transplantation of autologous BMC + CPG after 6 weeks. The results of this translational study imply that iMSCs represent a valuable future treatment option for load-bearing bone defects in humans.

Metabolic and behavioral parameters of mice with reduced expression of Syndecan-1.

Energy balance is essential for all species. Ligand-receptor interactions mediate processes that regulate body activities like reproduction and metabolism based on the energy status. Such receptors are the heparan sulfate proteoglycans and specifically the family of syndecans. Therefore we investigated the differences of metabolic parameters of heterozygous Syndecan 1 mice (Sdc1+/-) with reduced expression of Sdc1 and the corresponding wild type mice. Sdc1+/- mice have a reduced body weight although they show increased leptin and decreased corticosterone levels. Furthermore, their food and water intake is increased. This is accompanied with less adipose tissue, smaller adipocytes and thus an increased density of adipocytes. For the detailed analysis of the metabolism the automated PhenoMaster system has been used, which allowed continuous and undisturbed recording of food and water intake, energy expenditure and movement. The reason for the lower body weight was the higher energy expenditure of these animals compared to controls. Additionally, female Sdc1+/- mice showed an increased locomotor activity. Referring to organs, the intestine in Sdc1+/- mice was heavier and longer, but no differences at the cellular level could be observed. These findings were independent of normal mating or vice versa embryo transfers of Sdc1+/- and wild type embryos in recipient females of the other genotype. Herein we showed that the reduced expression of Sdc1 led to an altered metabolism on fetal as well as on maternal side, which may play a role in the growth restriction observed in human pregnancy pathologies and in mice lacking Sdc1.

Current Distribution of Rodentibacter Species Among the Mice and Rats of an Experimental Facility.

The uncertain taxonomy of [Pasteurella] pneumotropica and other rodent Pasteurellaceae has hindered the acquisition of knowledge on the biology and disease for this group of bacteria. Recently, these organisms have been reclassified within the new genus Rodentibacter. In this study, we documented which of the new described Rodentibacter spp. are present in the mouse and rat microbiologic units of an experimental facility. Screening all of the microbiologic units populated with mice and rats yielded 51 Rodentibacter isolates. Molecular and phenotypic diagnosis indicated the colonization of mice by R. pneumotropicus and R. heylii, whereas R. ratti and R. heylii were found in rats. Overall, we document the association of laboratory rodents with 3 of the newly described Rodentibacter. Diagnostics of the Rodentibacter spp. at the species level can decisively contribute to the progress of knowledge on these bacteria.

Leucobacter muris sp. nov., isolated from the nose of a laboratory mouse.

A Gram-stain-positive, rod-shaped, aerobic, non-motile, white, opaque bacterial isolate, designated 924/12T, was isolated from the nose of a laboratory mouse in Düsseldorf, Germany. The 16S rRNA gene sequence analyses indicated the phylogenetic position of the strain within the genus Leucobacter. Similarity levels over 97 % were recorded between the 16S rRNA gene sequence of strain 924/12T and the type strains of the species Leucobacter chironomi DSM 19883T (99.5 %), followed by Leucobacter celersubsp. astrifaciens CBX151T (97.6 %), Leucobacter celersubsp. celer NAL101T (97.5 %), 'Leucobacter kyeonggiensis' F3-P9 (97.5 %), Leucobacter zeae CC-MF41T (97.3 %), Leucobacter chromiiresistens JG31T (97.1 %), Leucobacter triazinivorans JW-1T (97.1 %), Leucobacter corticis 2 C-7T (97.0 %) and Leucobacter aridicolis CIP108388T (97.0 %). DNA-DNA hybridization and whole genomic comparison, mandatory to taxonomically separate strain 924/12T from the type strain of L. chironomi, revealed similarity values of 40.4 and 30.8 %, respectively, thus below the threshold of 70 % recommended differentiating between species. The cell-wall amino acids of the novel isolate were diaminobutyric acid, alanine, glycine, threonine and glutamic acid. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid and one unknown lipid, whereas the predominant menaquinones were MK-11 and MK-10. The genomic DNA G+C content of strain 924/12T was 70.6 mol%. Phylogenetic analyses based on the 16S rRNA gene sequences and the phenotypical differences between strain 924/12T and the other closely related type strains of the genus Leucobacter indicated that strain 924/12T represents a novel species within the genus Leucobacter, family Microbacteriaceae, for which the name Leucobacter muris sp. nov. is proposed. The type strain is 924/12T (=DSM 101948T=CCM 8761T).

Biomechanical Stability and Osteogenesis in a Tibial Bone Defect Treated by Autologous Ovine Cord Blood Cells-A Pilot Study.

The aim of this study was to elucidate the impact of autologous umbilical cord blood cells (USSC) on bone regeneration and biomechanical stability in an ovine tibial bone defect. Ovine USSC were harvested and characterized. After 12 months, full-size 2.0 cm mid-diaphyseal bone defects were created and stabilized by an external fixateur containing a rigidity measuring device. Defects were filled with (i) autologous USSC on hydroxyapatite (HA) scaffold (test group), (ii) HA scaffold without cells (HA group), or (iii) left empty (control group). Biomechanical measures, standardized X-rays, and systemic response controls were performed regularly. After six months, bone regeneration was evaluated histomorphometrically and labeled USSC were tracked. In all groups, the torsion distance decreased over time, and radiographies showed comparable bone regeneration. The area of newly formed bone was 82.5 ± 5.5% in the control compared to 59.2 ± 13.0% in the test and 48.6 ± 2.9% in the HA group. Labeled cells could be detected in lymph nodes, liver and pancreas without any signs of tumor formation. Although biomechanical stability was reached earliest in the test group with autologous USSC on HA scaffold, the density of newly formed bone was superior in the control group without any bovine HA.

Acinetobacter species in laboratory mice: species survey and antimicrobial resistance.

The extra-hospital epidemiology of Acinetobacter infections is a subject of debate. In recent years, the prevalence of animal multidrug-resistant Acinetobacter infections has increased considerably. The goal of the present study was to specify Acinetobacter species isolated from laboratory mice and to test them for their antimicrobial susceptibility. During routine microbiological monitoring of laboratory mice, 12 Acinetobacter spp. were isolated. By means of 16S rRNA and rpoB gene sequencing, seven of the isolates were identified as Acinetobacter radioresistens, three isolates belonged to Acinetobacter genomospecies 14BJ, one isolate was classified as Acinetobacter pitii and one as Acinetobacter sp. ANC 4051. The distribution of the minimal inhibitory concentration (MIC) values was uniform for 21 of the 23 antimicrobial agents tested, whereas a broad MIC distribution was recorded for tulathromycin and streptomycin. The MIC values recorded were low for the majority of the antibiotics tested. Nevertheless, very high MIC values, which will probably render a therapeutic approach using these substances unsuccessful, were recorded for florfenicol, tiamulin, tilmicosin and cephalothin in most of the isolates. In conclusion, we document colonization of laboratory mice with different Acinetobacter species, displaying similar antibiotic susceptibility profiles, with possible implications in the Acinetobacter epidemiology as well as in the husbandry and experimentation of the colonized animals.

From the [Pasteurella] pneumotropica complex to Rodentibacter spp.: an update on [Pasteurella] pneumotropica.

The species [Pasteurella] pneumotropica has been reclassified into the new genus Rodentibacter, within the family Pasteurellaceae. Along with the type species (Rodentibacter pneumotropicus) of the new genus, seven new species have been named. These organisms were formerly mainly known as the [P.] pneumotropica complex and [P.] pneumotropica was considered as the most important Pasteurellaceae species colonizing laboratory rodents. The aim of this review is to update the veterinary relevant aspects of clinical manifestations, pathogenesis, virulence and diagnostics of members of Rodentibacter with a focus on the most important species from a veterinary perspective. The organisms are obligate commensals of the mucous membranes and members of Rodentibacter are not able to persist for long in the environment. Members of Rodentibacter spp. are responsible for the most prevalent bacterial infections in laboratory mice and rats, but are also common in rodents outside laboratory settings. Some Rodentibacter spp. produce mainly localised disease in connection with favouring factors and seldomly act as primary pathogens in healthy immunocompetent animals. The subclinical infection with Rodentibacter spp. can affect the results of certain types of research using contaminated animals thus placing them on a list of microbes which are often not tolerated in experimental rodent facilities. The presences of RTX toxins, YadA-like proteins and a capsule with possible role in the pathogenesis have been described. Some species of Rodentibacter are able to form robust biofilms which might be involved in colonisation and persistence within the host. Current possibilities for diagnostics and differentiation among Rodentibacter spp. are outlined and options for treatment and control are provided.

Survival of bacteria of laboratory animal origin on cage bedding and inactivation by hydrogen peroxide vapour.

This study aims to determine the ability of laboratory animal bacteria to resist desiccation and inactivation by hydrogen peroxide vapour (HPV) on paper bedding pieces. Bedding pieces were saturated with bacterial suspensions in water or 2% (w/v) bovine serum albumin (BSA) in water, and held in a mouse facility. Viable counts showed variable survival rates over time for the bacterial species used ([ Pasteurella] pneumotropica, Muribacter muris, Pseudomonas aeruginosa, Acinetobacter redioresistens, Escherichia coli, Klebsiella oxytoca, Bordetella bronchiseptica, Bordetella hinzii, Enterococcus faecalis, ß-haemolytic Streptococcus spp., Staphylococcus aureus and Staphylococcus xylosus). Overall, BSA increased bacterial survival in the bedding pieces. The survival rates of Bacillus safensis were not influenced by BSA but depended on sporulation. When bedding pieces and Petri dishes inoculated with E. coli, P. aeruginosa and S. aureus were subjected to HPV disinfection, all bacterial species on the bedding pieces inoculated with bacterial suspensions in water were readily inactivated. By contrast, S. aureus and P. aeruginosa, but not E. coli cells survived HPV treatment in high numbers when inoculated on bedding pieces as a BSA suspension. Notably, all three bacterial species were readily inactivated by HPV even in the presence of BSA when smeared on smooth surfaces. In conclusion, the suspension medium and the carrier can influence the environmental survival and susceptibility of bacterial species to HPV. Our results may help to develop standard protocols that can be used to ensure the microbiological quality of experimental rodent housing.

Synergistic effects of HBO and PRP improve bone regeneration with autologous bone grafting.

Bone defects remain a challenge for patients and orthopaedic surgeons. Autologous transfer of cancellous bone grafts remains the standard of care. However, in recent years various osteoinductive substitute materials, such as platelet rich plasma (PRP) and hyperbaric oxygen therapy (HBO) have been shown to improve bone healing. This study evaluates the effects of a combined application of PRP and HBO with autologous bone grafting in an animal model. In 48 New Zealand White rabbits bone defects at the radius were filled with autologous bone harvested at the iliac crest. This was combined with application of autologous PRP and/or HBO treatment for the duration of this study. After 3 and 6 weeks histomorphometric, immunohistochemical and radiologic evaluations were performed. All animals tolerated the treatment well. Improved bone regeneration was shown in all groups at 6 weeks compared to 3 weeks. Additional application of PRP and HBO resulted in an increase in new bone formation and increased neovascularization at 3 and 6 weeks. There was no statistical significant difference between PRP and HBO application in these regards. A combinatory use of PRP and HBO resulted in an increased bone regeneration and neovascularization compared to all other groups. This study provides evidence for an improvement of bone regeneration with the combinatory application of PRP and HBO to autologous cancellous bone grafts in a model of weight bearing bone defects in rabbits. Also synergistic effects of these two measures on angiogenesis were evident.

Radiographic Morphometry of the Lumbar Spine in Munich Miniature Pigs.

The incidence of human spinal column disease remains high, and animal models still play important roles in prophylactic, diagnostic, and therapeutic research. Because of their similar size to humans, pigs remain an important spine model. For pigs to serve as a model for the human spine, basic similarities and differences must be understood. In this study, morphometric data of the lumbar spine of Munich miniature pigs (Troll) were recorded radiologically, evaluated, and compared with recorded human data. Whereas humans have a constant number of 5 lumbar vertebrae, Munich minipigs had 5 or 6 lumbar vertebrae. Compared with their human counterparts, the lumbar vertebral bodies of the minipigs were remarkably larger in the craniocaudal (superior-inferior) direction and considerably smaller in the dorsoventral and laterolateral directions. The porcine vertebral canal was smaller than the human vertebral canal. The spinal cord extended into the caudal part of the porcine lumbar vertebral canal and thus did not terminate as cranial, as seen in humans. The lumbar intervertebral spaces of the pig were narrower in craniocaudal direction than human intervertebral spaces. These differences need to be considered when planning surgical actions, not only to avoid pain and irreversible damage to the minipigs but also to achieve accurate scientific results.