• Journal of Chest Surgery
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• 제23권4호
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• Journal of Chest Surgery
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• 제33권6호
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• pp.469-475
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• 2000

Background: Thoracic aortomyoplasty is one of the surgical treatment for heart failure and has advantages over artificial heart or intraaortic balloon pumps. It uses autogenous skeletal muscles and solves problems such as energy source. However its use in clinical settings has been limited. This preliminary study was designed to develop surgical technique and to determine the effect of acute descending thoracic aortomyoplsty. Material and Method: Thirteen adult Mongrel dogs were used. The left latissimus dorsi muscle was wrapped around the descending aorta under general anesthesis. Swan-Ganz and microtipped Millar catheter were used for the hemodynamics and endocaridial viability ratio. Data were collected with myostimulator on and off in normal hearts and the ischemic hearts. Result: In normal hearts, the mean aortic diastolic pressure increased from 72$\pm$15mmHg at baseline to 78$\pm$13mmHg with stimulator on. Coronary perfusion pressure increased from 61$\pm$11mmHg to 65$\pm$9mmHg. Diastolic time increased from 0.288$\pm$0.003 msec to 0.290$\pm$0.003msec. Systolic time decreased from 0.164$\pm$0.002msec to 0.160$\pm$0.002 msec. Endocardial viability ratio increased from 1.21$\pm$0.22 to 1.40$\pm$0.18. In ischemic hearts, mean aortic diastolic pressure incrased from 56$\pm$21mmHg at baseline to 61$\pm$15mmHg with stimulator on. Coronary perfusion pressure increased from 48$\pm$17mmHg to 52$\pm$15mmHg. Diastolic time increased from 0.290$\pm$0.003 msec to 0.313$\pm$0.004msec. Systolic time decreased from 0.180$\pm$0.002 msec to 0.177$\pm$0.003 msec. Endovascular viability ratio increased from 0.9$\pm$0.31 to 1.1$\pm$0.31. The limited number of cases ruled out the statistic significance. Conclusion: Descending thoracic aortomyoplasty is a simple operation designed to use patient's own skeletal muscles. It trends to increase diastolic augmentation and coronary perfusion pressure. Modification of surgical technique and stimulator protocol would maximize the effect to assist the heart.

• Journal of Chest Surgery
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• 제40권4호
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• pp.256-263
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• 2007

배경: 혈관내막과다증식은 혈관평활근세포가 내막에서 과다증식하여 나타나며, epigallocatechin-3-gallate(EGCG)는 혈관평활근세포의 증식을 억제하는 효과가 있는 것으로 알려져 있다. 따라서 EGCG는 혈관내막과다증식을 억제할 수 있을 것으로 생각된다. 대상 및 방법: 다른 농도의 EGCG를 포함한 배양 배지에서 인간제대정 맥내피세포(HUVEC)와 쥐대동맥평활근세포(RASMC)를 배양하고, 세포증식과 이동속도를 측정하였다. 20마리의 개의 양측 경동맥에 자가경정맥을 이식하였으며, 실험군(n=10)에 대해서는 정맥도관을 이식 전 30분간 EGCG용액에 보관하였으며, 이식 후 300mM의 EGCG를 혈관주위에 도포하였다. 6주 후에 경정맥이식편의 내막과 중간막의 두께를 측정하였다. 결과: 내피세포와 혈관평활근세포의 증식은 EGCG에 의해 억제되었다. 혈관평활근세포의 이동성은 EGCG에 의해 억제되었으나, 내피세포의 이동성은 영향을 받지 않았다. 동물실험 결과 대조군에 비해 EGCG군에서 내막의 두께가 얇았으며(p<0.05), 중간막의 두께는 두 군간에 차이가 얼었고, 내막/중간막의 두께비는 EGCG군에서 낮게 관찰되었다(p<0.05). 결론: EGCG는 혈관수술 후 혈관내막과다증식을 억제하는 효과가 있으며, 이는 혈관평활근세포의 증식 및 이동을 억제하여 효과를 나타낸다고 생각된다. 따라서 EGCG는 혈관내막과다증식을 예방하는 치료에 효과적으로 사용될 수 있을 것으로 생각된다.

• Journal of Periodontal and Implant Science
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• 제27권2호
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• pp.329-346
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• 1997

Dental implants have been developed for enhancement of osseointegration. Biocompatibility, bone affinity and surface characteristics of dental implants are very important factors for osseointegration. The aim of the present study was to determine the cytotoxicity and the bone affinity of titanium phosphide(Ti-P) implant material. The Ti-P surface was obtained by vacuum sintering of titanium within compacted hydroxyapatite powder. The composition and the chemical change of the surface were determined by Auger electron spectroscopy. The in vitro cytotoxicity was evaluated by the viability of the bone cells and macrophages obtained from chicken embryo and rat,s peritonium, respectively. For the comparative evaluation, 316L stainless steel, commercially pure titanium and Ti-P materials, prepared in size of 1O.0mm in diameter and 5.0mm in height, were immersed separately in bone cells and macrophages for 10 days. For the evaluation of the in vivo bone affinity, 316L stainless steel, commercially pure titanium and Ti-P materials, prepared in size of 5.0mm in diameter and 10.0mm in length, were implanted after drilling in diameter 5.5mm in femurs of 2 dogs weighing 10Kg more or less. Six weeks after implantation the specimens were prepared for histopathological examination and were observed under light microscope. In comparison of in vitro bone cell viability, Ti-P and commercially pure titanium groups were not significantly different from control group (p>O.1), but 316L stainless steel group was significantly lower than control group(p<0.05). There was no statistical difference in the viability of macrophages between 3 different groups and control group(p>O.l). In comparison of in vivo study, 316L stainless steel and commercially pure titanium showed fibrous encapsulation, but Ti-P showed remarkable new bone formation without any fibrous tissue. The results demonstrate that Ti-P has favorable biocompatibility and bone affinity, and suggest that dental implants with Ti-P surface may enhance osseointegration.

• Journal of Periodontal and Implant Science
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• 제42권1호
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• pp.13-19
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• 2012

Purpose: The aim of this study was to examine whether a previous peri-implantitis site can affect osseointegration, by comparing implant placement at a site where peri-implantitis was present and at a normal bone site. A second aim of this study was to identify the tissue and bone reaction after treating the contaminated implant surface to determine the optimal treatment for peri-implant diseases. Methods: A peri-implant mucositis model for dogs was prepared to determine the optimal treatment option for peri-implant mucositis or peri-implantitis. The implants were inserted partially to a length of 6 mm. The upper 4 mm part of the dental implants was exposed to the oral environment. Simple exposure for 2 weeks contaminated the implant surface. After 2 weeks, the implants were divided into three groups: untreated, swabbed with saline, and swabbed with $H_2O_2$. Three implants from each group were placed to the full length in the same spot. The other three implants were placed fully into newly prepared bone. After eight weeks of healing, the animals were sacrificed. Ground sections, representing the mid-buccal-lingual plane, were prepared for histological analysis. The analysis was evaluated clinically and histometrically. Results: The untreated implants and $H_2O_2$-swabbed implants showed gingival inflammation. Only the saline-swabbed implant group showed re-osseointegration and no gingival inflammation. There was no difference in regeneration height or bone-to-implant contact between in situ implant placement and implant placement in the new bone site. Conclusions: It can be concluded that cleaning with saline may be effective in implant decontamination. After implant surface decontamination, implant installation in a previous peri-implant diseased site may not interfere with osseointegration.

• Journal of Periodontal and Implant Science
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• 제47권3호
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• pp.143-153
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• 2017

Purpose: The aim of the present exploratory study was to evaluate extraction socket healing at sites with a history of periodontal and endodontic pathology. Methods: The mandibular 4th premolar teeth in 5 adult beagle dogs served as experimental units. Periodontal and endodontic lesions were induced in 1 premolar site in each animal using wire ligatures and pulpal exposure over 3 months (diseased sites). The contralateral premolar sites served as healthy controls. The mandibular 4th premolar teeth were then extracted with minimal trauma, followed by careful wound debridement. The animals were sacrificed at days 1, 7, 30, 60, and 90 post-extraction for analysis, and the healing patterns at the healthy and diseased extraction sites were compared using radiography, scanning electron microscopy, histology, and histometry. Results: During the first 7 days of healing, a significant presence of inflammatory granulation tissue was noted at the diseased sites (day 1), along with a slightly accelerated rate of fibrin clot resolution on day 7. On day 30, the diseased extraction sites showed a greater percentage of persistent fibrous connective tissue, and an absence of bone marrow formation. In contrast, healthy sites showed initial signs of bone marrow formation on day 30, and subsequently a significantly greater proportion of mature bone marrow formation on both days 60 and 90. Radiographs exhibited sclerotic changes adjoining apical endodontic lesions, with scanning electron microscopy showing collapsed Volkmann canals protruding from these regions in the diseased sites. Furthermore, periodontal ligament fibers exhibited a parallel orientation to the alveolar walls of the diseased sites, in contrast to a perpendicular arrangement in the healthy sites. Conclusions: Within the limitations of this study, it appears that a history of periodontal and endodontic pathology may critically affect bone formation and maturation, leading to delayed and compromised extraction socket healing.

• 한국임상수의학회지
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• 제11권2호
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• pp.529-537
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• 1994

Sector scanner which has a conical end is used to image through the intercostal space because heart is protected by the ribs. Cardiac data published all around the world were also obtained by sector scanner. Although scanners being used in every small animal practice and animal hospital at college in Korea include convex ape and linear type, linear type is not appropriate f3r cardiac scan because of a wide contact surface. The purpose of this study is to establish ultrasonographic images of normal cardiac structures by measuring shape, size of reflectable cardiac structure according to restraint position in scanning normal heart of the puppies with 6.5 MHz convex scanner(SonoAce 4500, Medison, Korea) used in our veterinary teaching hospital, Seoul national university. Seventeen male and female puppies considered having healthy hear by X-ray and clinical examination are used feom April to July 1994. Scanning point selection of probe head and the distinction of imaged cardiac structures were accomplished by necropsy and cardiac scanning performed through thoracotomy under general anesthesia. At 10 o'clock position of transducer(at an angle of 30$^{\circ}$ between imaginary line from elbow joint to 3rd sternum and probe head, 60$^{\circ}$ from body surface, 4th intercostal space of right thorax) with the marker of scanner toward the head of dogs right atrium, left atrium and left ventricle were observed in 2, 3, 4, 5 intercostal space(2cm from the sternum) of experimental dog positioned ventrodorsally under general anesthesia. Under these conditions, the numerical values of imaged diastolic hear are as follows : the distance from skin to apex(mean$\pm$S.D) 47.53$\pm$6.94mm, thickness of left ventricular wall 6.00$\pm$1.60mm, length of left ventricle 16.27$\pm$5.31mm, width of left ventricle 15,33$\pm$4.25mm, length of left atrium 12.33$\pm$3.82mm, width of left atrium 11. 33$\pm$3.94mm, length of right atrium 1.00$\pm$2.41mm, width of right atrium 11.21$\pm$2.76mm and the area of left ventricle 270.92$\pm$109.81mm$^2$, area of left atrium 98.00$\pm$41.08mm$^2$, area of right atrium 62.75$\pm$21.04mm$^2$.

• 한국임상수의학회지
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• 제11권2호
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• pp.545-552
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• 1994

This experiment was carried out to investigate the renditions to maintain good post-thaw motility and viability of canine spermatozoa when the semen was frozen using methanol. The semen from two male dogs which had been proven to be fertile in the previous one year was treated with different compositions of semen diluent and was frozen at different freezing temperatures, When canine semen was frozen at-2$0^{\circ}C$, -6$0^{\circ}C$, or -8$0^{\circ}C$, the spermatozoa frozen and stored at -2$0^{\circ}C$ showed very low post-thaw motility and viability from day 2 to 7 and showed no viability since day 15 after freezing. The spermatozoa frozen and stored at -6$0^{\circ}C$ or -8$0^{\circ}C$ showed higher post-thaw motility and viability on day 2, 1, 15 and 30 after freezing than that frozen and stored at-2$0^{\circ}C$(p<0.01), with no difference between two groups. Among different composition groups of the semen diluents of control(tris + egg yolk + glycerol), egg yolk-free, 히ycerol-free, and tris-free, Prior to freezing, the egg yolk-free diluent showed significantly love. motility and viability than the other diluents(p<0.05). On each thawing day (from day 2 to 15 after freezing), control group showed considerably higher motility and viability than the other groups(p<0.01). The canine spermatozoa frozen and stored at -6$0^{\circ}C$ and -8$0^{\circ}C$ showed gradual decrease of motility from day 2 to 30 after freezing and the spermatozoa of these two groups thawed on day 30 showed considerably love. motility than those thawed on day 2 after freezing, respectively(p<0.01). These results indicate that the freezing temperature of either -6$0^{\circ}C$ or -8$0^{\circ}C$ can be applicable to the freezing method using methanol and also all of the components of the semen diluent including cryoprotectant, buffer and cold-shock buffer are very important to maintain motility and viability of canine spermatozoa in the freezing and thawing procedure.

• 한국임상수의학회지
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• 제21권1호
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• pp.15-19
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• 2004

치료 실시중 세균의 항생제 내성 발현은 임상 분야의 중요한 문제점중 하나인데 중요한 원인중 하나는 원인세균의 분리와 그에 따른 항생제 감수성 검사 결과에 바탕을 두지 않은 무분별하며 적절치 않은 항생제를 선택함에 있다. 따라서 본 연구에서는 대학동물 병원에 내원한 임상증례로부터 채취한 임상검체에서 협기성 세균을 분리 동정하고 항생제 감수성 양상을 검사하고자 하였다. 이를 위해 2001년 5월부터 2002년 10월까지 서울대학교 동물병원에 내원한 개, 고양이 및 토끼로부터 채취한 임상검체에 대해 협기성 배양을 실시하고 분리 동정된 세균에 대해서는 표준 디스크 검사법을 이용해 항생제 감수성을 평가하였다. 총 13주; Bacteroidesspp. (3주), Fusobacterium spp. (2주), Peptostreptococcus spp. (2주), Porphyromonas gingivalis (2주), Prevotella spp. (3주), Propionibacterium acnes (1주)의 혐기성 세균이 분리동정 되었으며 항생제 감수성 검사에서는 Fusobucterium varium 1주만이 norfloxacin 에 저항성을 나타내었으나 그 외 모든 분리주가 검사대상 항생제에 대한 감수성이 있는 것으로 나타났다.

• 한국임상수의학회지
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• 제19권2호
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• pp.186-190
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• 2002

아토피성 피부염은 면역계재성 피부질환으로 소양증이 주요 증상이며 이의 치료가 필수적이다. 따라서 개에서 제2세대 항히스타민제의 임상적용을 위해 피부에 히스타민에 의해 유발된 팽진과 발적에 대한 loratadine, cetirizine과 terfenadine의억제 효과를 비교하였다. 3종의 항히스타민제는 대조군에 비해 매우 유의하게 발적반응을 억제하였으며(p<0.01) cetirizine이 다른 제제에 비해 높은 억제효과를 보였다. 3종의 항히스타민제는 팽진 반응을 억제하는 효과를 보였으며 loratadine의 억제효과가 일정하며 지속적이었다. 따라서 제 2세대 항히스타민제인 loratadine과 cetirizine은 개에서 아토피성 피부염의 소양증 치료에 적용할 수 있는 항히스타민제로 사료된다. 특히 스테로이드제제를 대체할 수 있는 치료효과를 보일 것으로 판단된다.