• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.416-420
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• 1998

Flow-volume loop is known to be useful in the diagnosis of upper airway obstruction. In cases of tracheal obstruction, characteristic features such as fixed or variable upper airway obstruction patterns give clue to the diagnosis. But the flow-volume loop of unilateral mainstem bronchial stenosis is not known well. There is controversy in patterns of flow-volume loop in unilateral mainstem bronchial stenosis (restrictive pattern or biphasic pattern). We report a case of biphasic flow-volume loop in left mainstem bronchial stenosis(4-5 mm in diameter) as a sequela of endobronchial tuberculosis, which recovered normal flow-volume loop after metallic stent insertion and 2 months later showed reappearance of biphasic pattern because of restenosis of left mainstem bronchus due to growth of granulation tissue at the stent site.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.216-221
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• 2022

Biocompatible polysaccharide coating technology can be a promising solution to overcome unexpected diseases caused by inflammatory reactions of metallic biomaterials (e.g., stent restenosis, etc.). However, due to their inherent hydrophilicity, it is difficult to maintain the coating layer for a long time in the physiological wet-environment. Herein, catechol functionalized hyaluronic acid was synthesized and introduced to the polymeric stent (polylactic acid) as the adhesive biocoating material. Surprisingly, even with the low degree of substitution of catechol (1.26%), a significant improvement in the underwater stability was observed, confirmed by capillary experiments and spectroscopic analysis. Our results may provide an insight into the positive role of catechol molecular adhesive group in the in-vivo stability of biocoating materials.

• Polymer(Korea)
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• v.33 no.6
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• pp.620-624
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• 2009

Biomedical metal implants have been used clinically for replacement, restoration, or improvement of injury bodies based on high mechanical properties, but it has some risks such as the inflammatory, late thrombosis, or restenosis due to the low biocompatibility and toxicity. In various techniques of surface treatment developed to preserve these drawbacks, this study examined the electrospray coating technology with biodegradable poly (lactic-co-glycoic acid) (PLGA) on metal surface. Based on fundamental examination of electrospraying and solution parameters, the surface morphology of coated film was closely related to the boiling point of solvent, in-flight distance, and droplet size. The thickness of polymer film was linearly proportional to the emerged volume. This result exhibits that the polymeric droplets were continuously deposited on the polymer film. Therefore, the electrospray coating technology might be applied into the fabrication of single/multi-layered polymer film in nano-/micro-thickness and the control of the topology for biomedical metal implants including stents.

• Korean Journal of Bronchoesophagology
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• v.2 no.2
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• pp.213-221
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• 1996

To evaluate the clinical effectiveness of expandable metallic stents, the stents were implanted under endoscopic guidance with local anesthesia or general anesthesia for maintenance of the constructed subglottic space of trachea. The nine patients with respiration difficulty were subjected for expandable stents. The stenosis of upper airway were due to the framework problem of subglottic trachea and tracheostoma after total laryngectomy. Stents were constructed of 0.4 m stainless steel win in a zigzag configuration of 8 bends. A single stent was 20 m in diameter when fully expanded and 20 mm long. The stents were placed accurately to the stenotic site and followed to the 5 month after stent placement. The stenotic area became narrowed with overgrowing of granuloma in all patients and the metallic stents were removed and the stenotic area reconstructed surgically. As conclusion, this technique for the treatment of the subglottic trachea showed simple and safe, but highly recurred due to overgrowing of granuloma. We suggest that the expandable metallic stent is not encouraging in this study.

• Tuberculosis and Respiratory Diseases
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• v.41 no.1
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• pp.47-50
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• 1994

To maintain an adequate airway in a patient with tracheobronchial narrowing coming from various causes, prosthetic tracheobronchial stents provide palliative treatment for narrowed airways where surgical resection is inadvisable. After insertion, previous reported complications were granuloma formation, dysphagia, suction catheter entrapment and fatal massive hemoptysis. We report, a case of complication associated with expandible metallic stent with endobronchial stenosis due to tuberculosis.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.4
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• pp.423-439
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• 2012

This case report described a technique utilizing a computer-aided design (CAD)/computer-aided machining (CAM) - guided surgical implant placement and prefabricated temporary fixed prosthesis for an immediately loaded restoration. The advantages of CAD/CAM guided implant procedures are flapless, minimally invasive surgery and shorter surgery time. With this technique, less postoperative morbidity and delivery of prosthesis for immediate function would be possible. A patient with an edentulous maxilla received 8 implants in maxilla using CAD/CAM surgical templates. Prefabricated provisional maxillary implant supported fixed prosthesis were connected immediately after implant installation. Provisional prosthesis was evaluated for aesthetics, function during 6 months. Definitive implant supported fixed porcelain fused metal bridges were fabricated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3572-3578
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• 2011

In Positron Emission Tomography Computed Tomography, Standardized Uptake Value(SUV)is most generally used to discern tumors. However, SUV may be influenced other factors. In this study, experiment was conducted distrotion in image and change in SUV according to substance with GEMINI TF PET/CT of Philips.. SUV for materials resulted in 1.8 for stainless, 1.4 for stent, 2.4 for iodine contrast medium, 2.6 for Barium Sulfate, 1.6 for Gypsum, and 1.4 for paraffin respectively. The distortion of image was remarkable for the iodine contrast medium and Barium Sulfate. For the barium sulfate, the higher the density, the larger the distrotion of the images. As a result of test, it appeared that the metallic substance whose atomic number is low and contrast medium whose concentration is low didn't affect the distortion in image and the change in SUV. However, it tis necessary to minimize distortion in image and change in SUV, by removing the metallic substance and checking if there are contrast mdeium or before examination.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.256-261
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• 2018

Recently, the number of cardiovascular disease-related deaths worldwide has increased. Therefore, the importance of percutaneous cardiovascular intervention and drug-eluting stents (DES) has been highlighted. Despite the great clinical success of DES, the re-endothelialization at the site of stent implantation is retarded owing to the anti-proliferative effect from the coated drug, resulting in late thrombosis or very late restenosis. In order to solve this problem, studies have been actively carried out to excavate new drugs that promote rapid re-endothelialization. In this study, we introduced hydrophilic drug, tauroursodeoxycholate (TUDCA), that improves the proliferation of endothelial progenitor cells and promotes apoptosis of vascular smooth muscle cells. In addition, we utilized shellac, which is a natural resin from lac bug to coat TUDCA on the surface of the metal. When using conventional coating method including biodegradable polymers and organic solvents, phase separation between polymer and drug occurred in the coating layer that caused incomplete incorporation of drug into the polymer layer. However, when using shellac as a coating polymer, no phase separation was observed and drug was fully covered with the polymer matrix. In addition, by adjusting the composition of coating solution and modifying the hydrophilicity of the metal surface using oxygen plasma, the surface roughness decreased due to the increased affinity between coating solution and metal surface. This result provides a method of depositing a hydrophilic drug layer on the stent.

• The Korean Journal of Gastroenterology
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• v.72 no.5
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• pp.262-266
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• 2018

Surgery has been the standard treatment for perforated duodenal ulcers, with mostly good results. However, the resolution of postoperative leakage after primary repair of perforated duodenal ulcer remains challenging. There are several choices for re-operation required in persistent leakage from perforated duodenal ulcers. However, many of these choices are complicated surgical procedures requiring prolonged general anesthesia that may increase the chances of morbidity and mortality. Several recent reports have demonstrated postoperative leakage after primary repair of a perforated duodenal ulcer treated with endoscopic insertion using a covered self-expandable metallic stent, with good clinical results. We report a case with postoperative leakage after primary repair of a perforated duodenal ulcer treated using a covered self-expandable metallic stent.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.165-169
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• 2021

The objective of this study was to fabricate a novel hydrophobic stent for reducing restenosis by employing electron beam equipment. The stent was fabricated from a CoCr alloy tube by using a femtosecond laser and was treated with argon plasma. Subsequently, the stent's surface specification changed from hydrophilic to hydrophobic. Application of the electron beam offers several advantages such as a short processing time, whole surface reforming, and enhancement of material properties. As the surface of the stent was rendered hydrophobic, it can provide equivalent or enhanced mechanical properties and greater functionality with a higher radial force at the extended stent in a blood vessel. The obtained results corresponding to the mechanical properties indicate that the contact angle increased to approximately 130°, and the radial force increased to approximately 3 N. Furthermore, cell culture experiments were conducted for verifying whether cells were cultured on the surface-modified CoCr surface. Based on the obtained results, it is believed that an effective reduction in the restenosis of inserted vascular stents is possible.