Plastinate Library: A Tool to Support Veterinary Anatomy Learning

The shortage of both time for anatomy courses in the new veterinary medicine curriculum and instructors prepared to teach biomedical sciences has raised a crisis in anatomical education. Often, students spend time out of their classes trying to learn not only concepts but also laboratory-wise content from 2D materials such as books and videos. In addition, since the global COVID-19 pandemic lockdown, studying and habits have been reviewed, with many people adopting an at-home style. The purpose of this study was to evaluate students' acceptance of taking plastinate anatomical specimens to study at home. Thirty-three students were divided into three groups. G1 took home a set of kidneys composed of equine, bovine, and swine materials; G2 took home a pig kidney; and G3 (control) did not take any plastinate specimen home. Acceptance was assessed using an anonymous survey and interview. The method had high acceptance by the students, who believed that having the plastinate library was advantageous from different perspectives, including aiding with learning the differences between kidneys from different species, time flexibility, no commute to study after hours of laboratory classes, and time redistribution to prioritize the laboratory topics. The plastinate library has the potential to be a supportive tool for anatomy students in the contemporaneous veterinary curriculum paradigm, considering that the G1 and G2 groups used the plastinate specimens at home to complement the time they spent in the laboratory.

Using videos in active learning: An experience in veterinary anatomy

Examination failure rate is high in veterinary anatomy in Brazilian universities. We report here our active learning experience in which students recorded video reports on veterinary anatomical specimens of locomotor apparatus to support classic learning. Eighteen students were divided into 2 groups, case group (V3) and control (E). Case group students individually recorded video reports of prosected specimens weekly. Acceptance and efficacy of the strategy were assessed with a Likert scale anonymous questionnaire and students' scores in theoretical exams. The method was highly accepted and the performance test proved that recording videos is an effective strategy for active learning in anatomy.

Evaluation of global gene expression in regenerate tissues during Masquelet treatment

The Masquelet induced-membrane (IM) technique is indicated for large segmental bone defects. Attributes of the IM and local milieu that contribute to graft-to-bone union are unknown. Using a rat model, we compared global gene expression profiles in critically sized femoral osteotomies managed using a cement spacer as per Masquelet to those left empty. At the end of the experiment, IM and bone adjacent to the spacer were collected from the Masquelet side. Nonunion tissue in the defect and bone next to the empty defect were collected from the contralateral side. Tissues were subjected to RNA isolation, sequencing, and differential expression analysis. Cell type enrichment analysis suggested the IM and the bone next to the polymethylmethacrylate (PMMA) spacer were comparatively enriched for osteoblastic genes. The nonunion environment was comparatively enriched for innate and adaptive immune cell markers, but only macrophages were evident in the Masquelet context. iPathwayGuide was utilized to identify cell signaling pathways and protein interaction networks enriched in the Masquelet environment. For IM vs nonunion false-discovery rate correction of P values rendered overall pathway differences nonsignificant, and so only protein interaction networks are presented. For the bone comparison, substantial enrichment of pathways and networks known to contribute to osteogenic mechanisms was revealed. Our results suggest that the PMMA spacer affects the cut bone ends that are in contact with it and at the same time induces the foreign body reaction and formation of the IM. B cells in the empty defect suggest a chronic inflammatory response to a large segmental osteotomy.

Calvaria critical-size defects in rats using piezoelectric equipment: a comparison with the classic trephine

Calvarial critical-size defects in rats are used to study regeneration of both craniofacial bone and long-bones. For decades, the trephine technique has been used with no notable refinements in the procedure. The use of piezoelectric surgical equipment has increased in human clinical oral and maxillofacial surgery, neurosurgery, traumatology, and orthopedics, because the devices are easy to handle, and can cut bone without damaging sensitive soft tissues such as blood vessels, nerves, and membranes. This study evaluated and compared the surgical technique and bone regeneration process between a traditional hand-drill trephine and piezoelectric equipment in a critical-size calvaria defect in a rat model. Thirty SD male rats were randomly divided into two groups and had either a 7.9mm diameter circular defect created with trephine or a 7.0mm square defect using the piezoelectric device, both creating 49 mm2 defect areas. MicroCT and histology were performed at 45 and 75d after surgery. While trephine surgeries were performed faster than piezoelectric (25.5 minutes vs 38.5 minutes), the rate of complications was much higher, with 36% of trephine rats taking 20 minutes to achieve hemostasis. Although the extent of new bone formation was similar between the two surgical groups, the piezoelectric technique resulted in 50% less variability. No additional new bone formation was observed from 45 to 75d in both techniques. Piezoelectric technique represents a refined and more reproducible technique for calvarial defect generation in comparison to classic trephine methods.

Intraoperative delivery of the Notch ligand Jagged-1 regenerates appendicular and craniofacial bone defects

Each year, 33% of US citizens suffer from a musculoskeletal condition that requires medical intervention, with direct medical costs approaching $1 trillion USD per year. Despite the ubiquity of skeletal dysfunction, there are currently limited safe and efficacious bone growth factors in clinical use. Notch is a cell-cell communication pathway that regulates self-renewal and differentiation within the mesenchymal/osteoblast lineage. The principal Notch ligand in bone, Jagged-1, is a potent osteoinductive protein that positively regulates post-traumatic bone healing in animals. This report describes the temporal regulation of Notch during intramembranous bone formation using marrow ablation as a model system and demonstrates decreased bone formation following disruption of Jagged-1 in mesenchymal progenitor cells. Notch gain-of-function using recombinant Jagged-1 protein on collagen scaffolds promotes healing of craniofacial (calvarial) and appendicular (femoral) surgical defects in both mice and rats. Localized delivery of Jagged-1 promotes bone apposition and defect healing, while avoiding the diffuse bone hypertrophy characteristic of the clinically problematic bone morphogenetic proteins. It is concluded that Jagged-1 is a bone-anabolic agent with therapeutic potential for regenerating traumatic or congenital bone defects.

Lumbosacral plexus in Brazilian Common Opossum

The opossum has been suggested as an animal model for biomedical studies due to its adaptability to captivity and number of births per year. Despite many studies on morphology and experimental neurology using this opossum model, the literature does not offer details of the nerves of the lumbosacral plexus in this species. Ten lumbosacral plexus were dissected to describe the peripheral innervations of the Brazilian Common Opossum (Didelphis aurita) and compare the results with Eutheria clade species. The tensor fasciae latae muscle was absent and there was only one sartorius muscle for each limb. The distribution of the nerves were similar to other mammals, except for the caudal gluteal nerve, sartorius muscle innervations and the position of the pudendal nerve which arose from the major ischiatic foramen together with the ischiatic nerve, the cranial gluteal nerve and the caudal gluteal nerve. No anatomical variation was found. The special position of the pudendal nerve suggested that the Brazilian Common Opossum is a better model than rats or rabbits in surgical procedures with that specific nerve. In addition, the study revealed that the pelvic limb nerves are not an invariable structure of reference for muscle homology and homonym as reported previously. New investigation using other species of opossums are necessary to best comprehend the lumbosacral plexus distribution in the Methatheria clade and to confirm that other opossum species is eligible as a good model for pudendal nerve studies.

Novel rat model of nonunion fracture with vascular deficit

Nonunion fractures occur frequently in humans, with profound implications (medical and non-medical). Although there are numerous animal models to study pathogenesis and treatment of nonunion fractures, there is apparently the lack of a definitive model for atrophic nonunion fracture. Therefore, the objective was to develop a low-cost rat model of nonunion fracture with a vascular deficit that enabled standardized quantitative analysis of bone growth and regeneration. The model was developed with two surgeries, performed apart. The first involved osteotomy of the femur diaphysis, removal of periosteum and endosteum, isolation of the fracture site using a latex artefact (Penrose drain tube), and reduction of the fracture using an intramedullary pin, whereas the second surgery was to remove the latex artefact. Based on radiographic imaging, micro-CT and histological analyses done 125 days after the fracture was induced, there was clear evidence of atrophic nonunion fracture, without pin migration or specimen loss. Perceived advantages of this model included low cost, ease of reproducibility, lack of specimen loss, and, finally, the potential to assess bone growth and regeneration under poor vascular conditions.