In vitro evaluation of a hybrid negative pressure system for wound therapy.

OBJECTIVE: The objective of this study was to assess whether negative pressure could be maintained accurately and repeatably with a wall-suction-based hybrid negative pressure wound therapy (h-NPWT) system by comparing it with a commercial negative pressure wound therapy (NPWT) device. STUDY DESIGN: In vitro experimental study. METHODS: A commercial NPWT device (control) and three h-NPWT devices, with 0, 3, and 6 meters of additional tubing using the hospital-wall suction (groups 1, 2, and 3 respectively), were applied sequentially to a commercial NPWT dressing on a silicone skin substrate and set to run at a continuous pressure of -125 mmHg. The pressure within the wound space was monitored at 10 second intervals for 24 h. The process was repeated five times for each group. RESULTS: The commercial NPWT device produced an average pressure variance of 3.02 mmHg, and the h-NPWT produced average variances of 4.38, 4.24 and 4.20 mmHg for groups 1, 2 and 3, respectively. All groups produced an average pressure within 0.15 mmHg of -125 mmHg over the 24-hour period, and the h-NPWT systems produced the smallest range with all values remaining within a ±5% variation from -125 mmHg. CONCLUSION: The h-NPWT system achieved negative pressures that were comparable to those of a commercial control NPWT device. The addition of tubing between the skin substrate and the canister did not affect the pressure applied at the wound site. CLINICAL SIGNIFICANCE: The h-NPWT device tested in this study can be considered as an alternative for negative wound therapy when a commercial device cannot be used.

Retrospective Comparison of Titanium Hybrid Locking Plate with Stainless Steel Hybrid Dynamic Compression Plate for Pancarpal Arthrodesis: 23 Dogs.

OBJECTIVE: The aim of this study was to evaluate outcomes and complications of dogs that had pancarpal arthrodesis (PCA) using a titanium hybrid advanced locking plate system (ALPS) and stainless steel hybrid dynamic compression plate (HDCP). STUDY DESIGN: Retrospective observational study. METHODS: Medical records (2007-2020) were reviewed for cases that had PCA performed using ALPS or HDCP. Implant characteristics including metacarpal coverage (MCov), metacarpal width occupied by screw diameter percentage and carpal arthrodesis angle (CAA), complications and outcomes were recorded. RESULTS: Pancarpal arthrodesis was performed with ALPS on 15 limbs from 12 dogs, and HDCP on 14 limbs from 11dogs. Median follow-up time was 1,157 days (range: 62-1,902 days) for ALPS group and 340 days (range: 43-1,465 days) for HDCP. Median MCov for ALPS group was 74% (range: 60-87.5%) compared with 56.5% (range: 49.7-91.3%) for HDCP (p = 0.001). There was no difference in CAA and metacarpal width to screw diameter percentage between ALPS and HDCP group. Major and minor complications and surgical site infection rates were not statistically different between the two groups. Plate fracture occurred in 2/15 ALPS PCA and screw loosening occurred in 4/14 HDCP PCA. Full function was achieved in 8/12 and 8/11 of ALPS and HDCP cases, respectively, which was not statistically different (p = 0.76). CONCLUSION: The use of ALPS offers comparable performance to HDCP for PCA.

Minicircle Mediated Gene Delivery to Canine and Equine Mesenchymal Stem Cells.

Gene-directed tissue repair offers the clinician, human or veterinary, the chance to enhance cartilage regeneration and repair at a molecular level. Non-viral plasmid vectors have key biosafety advantages over viral vector systems for regenerative therapies due to their episomal integration however, conventional non-viral vectors can suffer from low transfection efficiency. Our objective was to identify and validate in vitro a novel non-viral gene expression vector that could be utilized for ex vivo and in vivo delivery to stromal-derived mesenchymal stem cells (MSCs). Minicircle plasmid DNA vector containing green fluorescent protein (GFP) was generated and transfected into adipose-derived MSCs from three species: canine, equine and rodent and transfection efficiency was determined. Both canine and rat cells showed transfection efficiencies of approximately 40% using minicircle vectors with equine cells exhibiting lower transfection efficiency. A Sox9-expressing minicircle vector was generated and transfected into canine MSCs. Successful transfection of the minicircle-Sox9 vector was confirmed in canine cells by Sox9 immunostaining. This study demonstrate the application and efficacy of a novel non-viral expression vector in canine and equine MSCs. Minicircle vectors have potential use in gene-directed regenerative therapies in non-rodent animal models for treatment of cartilage injury and repair.

Suppression of dedifferentiation and hypertrophy in canine chondrocytes through lentiviral vector expression of Sox9 and induced pluripotency stem cell factors.

OBJECTIVES: Prolonged in vitro culture of primary articular chondrocytes results in dedifferentiation to a fibroblast-like cell with reduced expression of the Sox9 transcription factor and the extracellular matrix protein collagen II. The ability to genetically-modify chondrocytes to allow both proliferation and maintenance of an articular phenotype may provide increased numbers of appropriate cells for regeneration of large cartilage defects. RESULTS: Canine chondrocytes were expanded in monolayer culture and transduced with a lentiviral vector expressing Sox9 or in combination with a multicistronic lentiviral vector expressing the four induced pluripotency stem (iPS) cell factors, Oct4, Klf4, Sox2 and c-Myc (OSKM). 3D pellet cultures of transduced cells in the presence of TGFß-3 revealed increased pellet size and higher levels of total glycosaminoglycan in both Sox9 and Sox9+ OSKM co-transduced chondrocytes compared to untransduced and green fluorescent protein expressing controls. Immunohistochemical detection of Sox9 and collagen II was evident in transduced cells (Sox9, OSKM, or Sox9+ OSKM) with very low levels in untransduced chondrocytes, demonstrating a dedifferentiated state (P < 0.01). The marker for chondrocyte hypertrophy, collagen X was highly expressed in Sox9 transduced chondrocytes but lower in OSKM or Sox9+ OSKM cells (P < 0.05). CONCLUSION: A combination of Sox9 and OSKM gene delivery to canine chondrocytes allows continuous proliferation in monolayer culture with a higher expression of col2a1 without an increase in the hypertrophy marker collagen X in 3D pellet cultures.

Canine elbow dysplasia: aetiopathogenesis and current treatment recommendations.

Elbow dysplasia is a common debilitating condition of large and giant breed dogs. Environmental factors and a complex genetic heritability play a role in predisposing dogs to elbow dysplasia with two aetiopathogeneses suggested for the development of the disease. Osteochondrosis was initially thought to cause elbow dysplasia, but more recent evidence has strongly supported various forms of joint incongruity as the most likely cause in most cases. Radioulnar length discrepancies and humeroulnar curvature mismatch have been implicated as the cause of medial coronoid disease and ununited anconeal process, but radial incisure incongruity and biceps/brachialis muscle forces could possibly play a role in some dogs. Treatment of elbow dysplasia should address articular pathology, such as fragmented coronoid process, osteochondrosis, cartilage damage and ununited anconeal process as well as any identified underlying causes. Finally, several palliative procedures have been developed to address more advanced elbow disease and might offer improved outcomes compared to conventional medical management.

Conditioned response to a magnetic anomaly in the Pekin duck (Anas platyrhynchos domestica) involves the trigeminal nerve.

There have been recent calls to develop protocols that collect unambiguous measures of behaviour using automatic techniques in conditioning experiments on magnetic orientation. Here, we describe an automated technique for recording the behaviour of Pekin ducks in a conditioning test that allows them to express unrestricted searching behaviour. Pekin ducks were trained to find hidden food in one corner of a square arena below which was placed a magnetic coil that produced a local magnetic anomaly. The trigeminal nerve was anaesthetised by injection of lignocaine hydrochloride 2-3 mm caudal to the medial canthus of each eye, medial to the globe, prior to the presentation of unrewarded tests. Lignocaine-treated ducks showed no initial preference for the magnetic anomaly whereas saline-treated control ducks showed a significant preference at the same age. A second experiment was undertaken in which the trigeminal nerve was surgically severed and 2-3 mm removed, and this surgery abolished the previously observed preference for the corner with the magnetic coil in a small number of ducks. These data show that Pekin ducks are able to detect and use magnetic stimuli to guide unrestricted search behaviour and are consistent with a hypothesis of magnetoreception involving a putative cluster of magnetite in the upper beak.