Geometric accuracy of an acrylonitrile butadiene styrene canine tibia model fabricated using fused deposition modelling and the effects of hydrogen peroxide gas plasma sterilisation

Background

Three-dimensional (3D) printing techniques have been used to produce anatomical models and surgical guiding instruments in orthopaedic surgery. The geometric accuracy of the 3D printed replica may affect surgical planning. This study assessed the geometric accuracy of an acrylonitrile butadiene styrene (ABS) canine tibia model printed using fused deposition modelling (FDM) and evaluated its morphological change after hydrogen peroxide (H₂O₂) gas plasma sterilisation. The tibias of six canine cadavers underwent computed tomography for 3D reconstruction. Tibia models were fabricated from ABS on a 3D printer through FDM. Reverse-engineering technology was used to compare morphological errors (root mean square; RMS) between the 3D-FDM models and virtual models segmented from original tibia images (3D-CT) and between the models sterilised with H₂O₂ gas plasma (3D-GAS) and 3D-FDM models on tibia surface and in cross-sections at: 5, 15, 25, 50, 75, 85, and 95% of the tibia length.

Results

The RMS mean ± standard deviation and average positive and negative deviation values for all specimens in E_FDM-CT (3D-FDM vs. 3D-CT) were significantly higher than those in E_GAS-FDM (3D-GAS vs. 3D-FDM; P < 0.0001). Mean RMS values for E_FDM-CT at 5% bone length (proximal tibia) were significantly higher than those at the other six cross-sections (P < 0.0001). Mean RMS differences for E_GAS-FDM at all seven cross-sections were nonsignificant.

Conclusions

The tibia models fabricated on an FDM printer had high geometric accuracy with a low RMS value. The surface deviation in E_FDM-CT indicated that larger errors occurred during manufacturing than during sterilisation. Therefore, the model may be used for surgical rehearsal and further clinically relevant applications in bone surgery.

Graphical abstract

Kynurenine 3-monooxygenase (KMO), and signal transducer and activator of transcription 3 (STAT3) expression is involved in tumour proliferation and predicts poor survival in canine melanoma

Canine melanoma is a malignant tumour that exhibits aggressive behaviour, and frequently metastasizes to regional lymph nodes and distant sites. Currently, there are no effective treatments or practical prognostic biomarkers for canine melanoma. The enzyme kynurenine 3-monooxygenase (KMO), which plays a central role in the tryptophan metabolism, has previously been identified as the main pathogenic factor in neurodegenerative diseases; however, it has recently been found to be positively associated with tumour malignancy in human hepatocellular carcinoma and canine mammary tumours. Signal transducer and activator of transcription 3 (STAT3) is a well-known oncoprotein contributing to the proliferation, survival, invasiveness and metastasis of a variety of cancers. Although whether STAT3 and KMO collaborate in tumorigenesis needs to be further verified, our previous findings showed that inhibition of KMO activity reduced activation of STAT3. This study investigated the expressions of KMO and STAT3/phosphorylated (pSTAT3) by immunohistochemical analysis in 85 cases of canine melanoma, showing their expression levels were high within highly mitotic melanoma cells. KMO Overexpression was significantly associated with increased STAT3 and pSTAT3 expressions. Melanoma tissues with higher KMO, STAT3 and pSTAT3 protein expressions were correlated with reduced survival rates of the canine patients. Moreover, inhibition of KMO activity in canine melanoma cells resulted in reduced cell viability, in addition to decreased expressions of STAT3 and pSTAT3. Our results indicated the significance of KMO and the potential role of KMO/STAT3 interaction in enhancing tumour development. Additionally, KMO and STAT3/pSTAT3 may be viewed as useful biomarkers for the prediction of prognosis of canine melanoma.

A novel PCR-based point-of-care method enables rapid, sensitive and reliable diagnosis of Babesia gibsoni infection in dogs

BACKGROUND

Babesia gibsoni (B. gibsoni) is an intraerythrocytic protozoan parasite of dogs that causes fever and hemolytic illness. A timely diagnosis is essential for the disease management.

RESULTS

Here, we report a QubeMDx PCR system which enables a rapid, sensitive and reliable diagnosis of B. gibsoni near the dog patient. Within 30 min, this diagnostic assay was able to detect as low as 0.002% parasitemia of the dog blood. Using clinical samples, this new assay was validated to demonstrate 100% agreement with real-time PCR.

CONCLUSIONS

This novel diagnostic method provides a reliable point-of-care test to assist in the identification of B. gibsoni.

Growth and Behavior of Congenitally Anophthalmic Lee-Sung Pigs

Circadian rhythm is usually regulated by the environmental light-dark cycle. Congenitally anophthalmic miniature pigs provide a valuable model for the study of factors affecting circadian rhythms in the absence of visual exposure to the light-dark cycle. This study investigated the growth and daily behavior patterns of Lee-Sung pigs with congenital anophthalmia. Growth in 5 Lee-Sung pigs (LSP) with congenital anophthalmia (LSP-A) and 10 normally developed pigs (LSP-N) was assessed when they were 1 through 6 mo old. Behavioral studies using digital video recording were completed in 6 sexually mature LSP (3 LSP-A and 3 LSP-N). MRI showed that LSP-A lose their vision because of a lack of retinal input and optic chiasm development. LSP-N and LSP-A did not differ in body weight or size at 2, 4, and 6 mo of age. Behavior and activity pattern studies showed that both LSP-A and LSP-N were active mainly during daylight, but LSP-A spent significantly more time exploring their environment during the day (28%) and night (10%) than did LSP-N. This study revealed that growth performance was similar between LSP-A and normal pigs, but their behavior and activity patterns differed. LSP-A showed circadian rhythm abnormalities similar to those in blind humans. This study provides basic data on LSP-A as a model for studying compensatory cross-modal brain plasticity and hormone regulation in the absence of retinal input is deficient and for understanding the role of circadian rhythm regulation.

A Novel Immunochromatographic Strip for Antigen Detection of Avian Infectious Bronchitis Virus

Avian infectious bronchitis virus (IBV) causes considerable economic losses in the poultry industry worldwide, including Taiwan. IBV is among the most important pathogens in chickens, and it spreads rapidly among flocks. In addition to dozens of known serotypes, new viral variants have emerged due to the viral evolution and antigenic variation in IBVs. Therefore, the development of a sensitive, specific, and easily performed assay is crucial for the rapid detection and surveillance of IBV infections. A rapid and simple immunochromatographic strip (ICS) was developed in this study by employing monoclonal antibodies against spike and nucleocapsid proteins of IBV as the tracer and the capture antibody. The ICS showed high specificity in detecting IBV antigens, including several IBV genotypes and novel variants, as opposed to three other common avian respiratory viruses. The detection limit of the strip reached 10^4.4 50% embryo-infective dose. Moreover, in the experimental chicken model, the strip test demonstrated consistency in detecting IBV with RT-PCR gene detection. Taken together, this antigen detection strip has the potential to serve as an on-farm rapid test for IBV; therefore, it may facilitate surveillance and control of the disease.

SEROEPIDEMIOLOGIC SURVEY OF CANINE LEPTOSPIROSIS IN NORTHERN TAIWAN DURING 2008–2015

Leptospirosis is an important infectious zoonosis that may cause life-threatening illness in both humans and animals. This study aimed to identify the serovars of Leptospira using the microscopic agglutination test (MAT) and the effect of season on serum-positive cases detected in National Taiwan University Veterinary Hospital from August 2008 to September 2015. This study also compared the characteristics of serum-positive and serum-negative cases. Among 159 suspected cases, 78 serum-positive (MAT titer [Formula: see text]) and 81 serum-negative cases were identified. In serum-positive cases, the most common pathogenic serovars were Canicola (18.2%), Icterohaemorrhagiae (23.6%), and Shermani (20.0%). Significantly more serum-positive cases were identified in fall (September to November) than other seasons ([Formula: see text]). Dogs aged 1–5 years (odds ratio [Formula: see text] 1.7) were more likely to be identified as being serum-positive cases of canine leptospirosis than serum-negative cases. However, no significant difference was observed regarding breed, gender, and regional distribution. The serum concentrations of liver enzymes, total bilirubin, blood urea nitrogen, and creatinine were elevated in both serum-positive and serum-negative cases, with no significance. White blood cell (WBC) counts of serum-positive cases were statistically higher than those of serum-negative cases ([Formula: see text]). In conclusion, more precaution must be taken with dogs aged 1–5 years because of their higher risk of leptospirosis; additionally, significantly elevated WBC count may be a suitable indicator in suspected cases of canine leptospirosis.

Implantation of tetrapod-shaped granular artificial bones or β-tricalcium phosphate granules in a canine large bone-defect model

We investigated biodegradability and new bone formation after implantation of tetrapod-shaped granular artificial bone (Tetrabone®) or β-tricalcium phosphate granules (β-TCP) in experimental critical-size defects in dogs, which were created through medial and lateral femoral condyles. The defect was packed with Tetrabone® (Tetrabone group) or β-TCP (β-TCP group) or received no implant (control group). Computed tomography (CT) was performed at 0, 4 and 8 weeks after implantation. Micro-CT and histological analysis were conducted to measure the non-osseous tissue rate and the area and distribution of new bone tissue in the defect at 8 weeks after implantation. On CT, β-TCP was gradually resorbed, while Tetrabone® showed minimal resorption at 8 weeks after implantation. On micro-CT, non-osseous tissue rate of the control group was significantly higher compared with the β-TCP and Tetrabone groups (P<0.01), and that of the β-TCP group was significantly higher compared with the Tetrabone group (P<0.05). On histology, area of new bone tissue of the β-TCP group was significantly greater than those of the Tetrabone and control groups (P<0.05), and new bone distribution of the Tetrabone group was significantly greater than those of the β-TCP and control groups (P<0.05). These results indicate differences in biodegradability and connectivity of intergranule pore structure between study samples. In conclusion, Tetrabone® may be superior for the repair of large bone defects in dogs.

Changes in bone regeneration by trehalose coating and basic fibroblast growth factor after implantation of tailor-made bone implants in dogs

In this study, we aimed to determine the effect of trehalose coating and the optimal dose of basic fibroblast growth factor (bFGF), an osteoinductive protein, loaded onto tailor-made bone implants for implant-induced bone formation in vivo. We fabricated tailor-made α-tricalcium phosphate bone implants (11 mm diameter with 2 parallel cylindrical holes). bFGF 0, 1, 10, 100 or 200 μg/implant was incorporated into implants with and without a trehalose coating, and these were subsequently implanted into dogs to correct temporal bone defects of the same size and shape. Four weeks after implantation, we analyzed the bone implants and surrounding tissues by using micro-computed tomography imaging and histological analyses, as well as gross evaluation. No significant difference in new bone formation was observed between implants with and without a trehalose coating at any of the bFGF doses. Bone implants with 100 and 200 μg bFGF showed significantly more new bone formation at the implant site and within the cylindrical holes of the implants than those without bFGF (P<0.05). However, heterotopic bone formation on the skull near the implant was observed in the group that received 200 μg bFGF. These results suggest that 100 μg bFGF is the optimal dose for this implant in dogs, and that the trehalose coating may not be necessary in vivo, probably due to the presence of blood proteins and electrolytes at the implant site.

Hepatocyte growth factor gene therapy prevents radiation-induced liver damage

AIM: To transfer human HGF gene into the liver of rats by direct electroporation as a means to prevent radiation-induced liver damage.

METHODS: Rat whole liver irradiation model was accomplished by intra-operative approach. HGF plasmid was injected into liver and transferred by electroporation using a pulse generator. Control rats (n = 8) received electrogene therapy (EGT) vehicle plasmid and another 8 rats received HGF-EGT 100 μg 48 h before WLIR. Expression of HGF in liver was examined by RT-PCR and ELISA methods. Apoptosis was determined by TUNEL assay. Histopathology was evaluated 10 wk after whole liver irradiation.

RESULTS: Marked decrease of apoptotic cells and down-regulation of transforming growth factor-beta 1 (TGF-β1) mRNA were observed in the HGF-EGT group 2 d after liver irradiation compared to control animals. Less evidence of radiation-induced liver damage was observed morphologically in liver specimen 10 wk after liver irradiation and longer median survival time was observed from HGF-EGT group (14 wk) compared to control rats (5 wk). (P = 0.031).

CONCLUSION: For the first time it has been demonstrated that HGF-EGT would prevent liver from radiation-induced liver damage by preventing apoptosis and down-regulation of TGF-β1.

Genomic deletion and p53 inactivation in cervical carcinoma

The tumor-suppressor gene p53 acts as "the guardian of the genome", sensing DNA damage and initiating protective responses. To examine the hypothesis that p53 abnormality leads to increased genomic alterations in primary tumor cells, our study utilized 51 primary tumors of cervical carcinoma and 10 microsatellite markers. These markers were mapped to the short arms of chromosomes 3 and 5, covering the regions 3p13-25 and 5p15.1-15.3. Genomic deletion on 3p and 5p was correlated with genetic or epigenetic p53 inactivation pathways, including p53 mutation, genetic deletion of p53 and cervical infection with human papillomavirus. The proportion of abnormal p53 was found to be significantly higher in the cases exhibiting loss of heterozygosity (LOH) on 5p (p < 0.001), supporting the hypothesis of the presence of a p53-dependent pathway to cervical tumorigenesis. In contrast, however, LOH on 3p was found to be independent of p53 inactivation. A common deletion region, 3p22-24, was identified in 44% of informative cases, and genomic loss at this specific region was correlated with early tumorigenic onset and poor grade of tumor differentiation. Diversity within the patterns of genomic alteration in the same form of cancer suggests different sets of risk/tumorigenic profiles, molecular pathogenesis, as well as prognosis and outcome.