Intraluminal Titanium Alloy Stent to Prevent Tracheal Stenosis in Tracheal Anastomosis.

BACKGROUND/AIM: Tracheal stenosis can cause respiratory problems in mature, small-breed dogs. This study aimed to evaluate the placement of an intratracheal titanium alloy stent to prevent tracheal stenosis in canine tracheal anastomosis. MATERIALS AND METHODS: The self-expandable intratracheal stent was an alloy of nickel and titanium, at the same atomic ratio. Vital signs and respiratory patterns, C-reactive protein, radiography, computed tomography, and endoscopy results after intraluminal stenting were assessed for 3-5 months. RESULTS: No dogs showed evidence of intraluminal tracheal stenosis or tracheitis in the region of stent insertion on tracheoscopy and computed tomography after tracheal stent placement. After 1-2 weeks of tracheal stent placement, all dogs resolved coughing and dyspnea signs and resumed normal activities. CONCLUSION: The intratracheal stent showed no movement or deformation in the trachea, and had flexibility and an appropriate radial force. Therefore, titanium alloy tracheal stents are useful in stenotic operations for tracheal reconstruction.

Evaluation of Renal Function in Obstructed Ureter Model Using 99mTc-DMSA.

BACKGROUND/AIM: Urinary obstruction is a condition of impaired urinary drainage, which may result in progressive renal deterioration. This study applied 99mTc-labeled dimercaptosuccinic acid (99mTc-DMSA) renal scintigraphy to a rabbit model of right ureter obstruction and evaluated its utility in studying obstructive renal diseases. MATERIALS AND METHODS: Complete unilateral ureter obstruction in rabbits was generated by complete ligation of the right ureter. Renal function was investigated during a 4-week post-obstruction period by obtaining planar images of 99mTc-DMSA activity following ear vein injection. Renal blood perfusion was evaluated by non-invasive scintigraphy in conjunction with parallel histological and hematological examinations. RESULTS: Renal perfusion was remarkably and rapidly reduced in the ureter-obstructed kidneys. During the experimental period, the size of left kidney appeared normal in the scintigraphic images, but the ureter-obstructed right kidney progressively became larger. Histopathological examination showed flattening and atrophy of tubules, enlargement of interstitial areas, accumulation of extracellular martices and infiltration of inflammatory cells in the obstreucted kidney. CONCLUSION: 99mTc-DMSA scintigraphy is a sensitive, non-invasive method to assess renal function in unilateral kidney diseases.

Osteogenic Evaluation of Hydroxyapatite Scaffold Loaded With Dexamethasone in Femoral Drill Holes.

BACKGROUND/AIM: Many cases of bone damage are due to trauma and metabolic diseases. This study aimed to evaluate bone regeneration into a porous hydroxyapatite (HA) scaffold using dexamethasone (DM)-loaded polymeric microspheres. MATERIALS AND METHODS: Four adult dogs were used to evaluate the in vivo performance of DM-loaded microspheres immobilized on the surfaces of porous HA scaffolds. Two 5-mm drill holes were created in both the left and right femurs of each dog. The experimental groups included a control group (drill holes filled with HA scaffold alone), a DM 20 group (holes filled with DM-loaded HA scaffold with 20 mg DM per scaffold), and a DM 100 group (hole filled with DM-loaded HA scaffold with 100 mg DM per scaffold). Resulting bone volume percentages and bone mineral densities were calculated by examing micro-computed tomographic (CT) images. RESULTS: The DM-loaded HA scaffold groups showed a gradual periosteal reaction two weeks after insertion of the HA scaffold into the femoral drill holes. Four weeks after HA scaffold insertion, the periosteal reaction in the femoral drill holes became denser. Eight weeks after insertion of DM-loaded HA scaffolds, clear images of the scaffold were observed in micro-CT images of the femoral drill hole. The DM 100 group had better bone healing tendencies (bone mineral density, bone mass, trabecular volume, bone surface, and trabecular thickness) than the DM 20 group. CONCLUSION: DM-loaded HA scaffolds are suitable platforms for distributing bioactive molecules during osteogenesis in femoral drill holes.

Evaluation of Goose-beak Bone Particles for Dentoalveolar Reconstruction in Dogs.

BACKGROUND/AIM: Tooth extraction is a common procedure in dental clinics. Tooth extraction can destroy gingiva, alveolar bone, periodontal ligaments and cement. If dental sockets are left as extracted, it will result in loss of teeth, as well as voice and aesthetic problems. A natural hydroxyapatite (HA) bioceramic bone graft substitute developed from goose-beak bone particles (GBPs) was used for dentoalveolar reconstruction in a canine model. MATERIALS AND METHODS: Four adult (18-22 months old) male beagle dogs weighing 8.2-9.6 kg were included in the study. Eight alveolar extraction sockets in the four dogs were divided randomly into two groups and a split-mouth design was established; control group, socket filled with commercial synthetic HA; tested group, socket filled with granulated GBP. RESULTS: Micro-CT analysis and hematoxylin and eosin and Masson's trichrome staining of non-decalcified sections were undertaken. Examination revealed that dentoalveolar reconstruction was initiated from the periphery of the host bone, and newly formed bone was well integrated with the GBP. Bone apposition was observed at the edge of the host bone-GBP interface. CONCLUSION: A natural ceramic powder obtained from GBP is suitable for use in dentoalveolar reconstruction in dogs.

Healing Effect of Platelet-rich Plasma on Decellularized Tracheal Allotransplantation in Rabbits.

BACKGROUND/AIM: The purpose of this study was to explore the effect of platelet-rich plasma (PRP) on enhancing healing of trachea allotransplantation and confirm the effect via parallel histological and tracheoscopic examinations in seven adult New Zealand White rabbits. MATERIALS AND METHODS: Harvested trachea was inserted into recipients with end-to-end anastomosis by a simple interrupted suture. PRP-treated rabbits were treated with 0.5 ml of PRP at the trachea grafts, while control rabbit allografts were treated with 0.5 ml of saline. RESULTS: Tracheoscopy of tracheal allografts treated with PRP revealed that the trachea was well healed with no stenosis. The healing effect in the PRP-treated rabbits increased tracheal activity and produced faster trachea regeneration compared to that in control rabbits. There was a good correlation between the subjective symptom of noisy breathing and the objective grading of tracheal stenosis. The tracheal allografts with suture materials appeared slightly pale and looked more like mucosa erosion than normal mucosa at four weeks post-surgery. Contact of trachea-to-transplanted grafts in PRP-treated rabbits was intimate with the surface of the transplanted region and showed high-density epithelialization. After 8 weeks, blood vessels were observed in the transplanted graft in PRP-treated rabbits. Normal epithelium was present in grafts at 8 weeks after allotransplantation. No CD20+ cells were detected in grafts but a few CD3+ cells were observed under the epithelium. CONCLUSION: The results of this study show that it is possible to perform tracheal reconstruction in rabbits treated with PRP after tracheal transplantation.

Cortisol Levels and Gastrointestinal Disorders After Stressful Surgery in Rabbits.

Rabbits are widely used in biomedical studies because they are docile and manageable. However, they are prone to gastrointestinal disorders due to their vulnerability to stress. Eighteen adult rabbits were used for allogenic tracheal surgery. The tracheas for allograft, 20-mm length, were transplanted into 20-mm tracheal defects. Immediately after surgery, most rabbits suffered from poor appetite. Food and water intake gradually recovered within 7 days after surgery, but six rabbits had severe anorexia from day 7 post-surgery. Four of these rabbits developed symptoms of diarrhea after surgery; three of them died several days after the onset of diarrhea, while one rabbit recovered. Gastrointestinal disorders need to be prevented in rabbits undergoing stressful surgery. Furthermore, it is important to choose the proper type and dose of analgesics in order to relieve postoperative pain. With this observation in mind, rabbits are not considered to be an appropriate model for stressful surgery.

Bone Regeneration of Hydroxyapatite with Granular Form or Porous Scaffold in Canine Alveolar Sockets.

This study was undertaken to assess bone regeneration using hydroxyapatite (HA). The primary focus was comparison of bone regeneration between granular HA (gHA) forms and porous HA (pHA) scaffold. The extracted canine alveolar sockets were divided with three groups: control, gHA and pHA. Osteogenic effect in the gHA and pHA groups showed bone-specific surface and bone mineral density to be significantly higher than that of the control group (p<0.01). Bone volume fraction, bone mineral density, and amount of connective tissue related to disturbing osseointegration of the gHA group was higher than in the pHA group. Quantity of new bone formation of the pHA group was higher than that of the gHA group. This study demonstrated that gHA and pHA are potentially good bone substitutes for alveolar socket healing. For new bone formation during 8 weeks' post-implantation, HA with porous scaffold was superior to the granular form of HA.

Effect of Hydrogen Dioxide Treatment on the Osteogenic Potential of Duck-beak Bone-derived Natural Bioceramic Microparticles.

BACKGROUND/AIM: As an alternative material to the autogenous bone, duck-beak bone particle for bone substitute have been attracting great attention due to their biological properties. To deliver the most favorable outcome of medical treatment, it is essential to study the effect of various processing methods of the duck-beak bone. In this study, we compared the two deproteinizing agents for manufacturing duck-beak bone. Group 1 was treated by a conventional chemical agent (ethylenediamine) and Group 2 by hydrogen dioxide (H2O2). In vitro and in vivo experiments were conducted in parallel to compare the cytocompatibility and osteogenic capability between two processing methods. For in vitro tests, human adipose-derived mesenchymal stem cells (hAD-MSCs) were planted onto each sample and their attachment and growing were evaluated. For in vivo biocompatibility and osteogenic properties, the samples were applied on the critical-sized calvarial bone defect of rats. Group 2 showed significantly higher cell attachment but Group1 showed slightly higher cell proliferation. In in vivo tests, all groups have shown biocompatibility and increased level of osteogenic potential. However, Group 2 had significantly higher bone regeneration (p<0.05). This experiment confirmed that H2O2 can be an optimal processing method for duck-beak bone particle.