• Title/Summary/Keyword: Biologic

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Expressions of transforming growth factor β in patients with rheumatioid arthritis and osteoarthritis (류머티스 관절염과 골관절염 환자에서 Transforming growth factor β의 발현 양상)

  • Kim, Chae-Gi;Yoon, Wern Chan;Song, Yong-Ho;Kim, Sang-Gyung;Choe, Jung-Yoon
    • IMMUNE NETWORK
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    • v.1 no.3
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    • pp.244-249
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    • 2001
  • The transforming growth $factor-{\beta}$ ($TGF-{\beta}$) is a multifunctional cytokine modulating the onset and course of autoimmune disease as shown in experimental models. In synovial inflammation, there is a potential role for $TGF-{\beta}$ in repairment, the inhibition of cartilage and bone destruction, and the down-regulation of immune response. The biologic effects of $TGF-{\beta}$ depend on the cell type, the isoform and the availability of active $TGF-{\beta}$. We investigated $TGF-{\beta}$ expression in patients with rheumatoid arthritis (RA) and compared to those of osteoarthritis (OA). And we determined a correlation between $TGF-{\beta}1$ and $TGF-{\beta}2$, and also the relationships between each $TGF-{\beta}$ isoform and the parameters for disease activity of RA. Methods: The study population consisted of 20 patients with RA and 20 patients with OA. The commercial ELISA kit was used to study $TGF-{\beta}1$ and $TGF-{\beta}2$ levels in peripheral blood (PB) and synovial fluids (SF). Results: 1) While PB $TGF-{\beta}1$ level was of no difference between RA and OA patient groups, SF $TGF-{\beta}1$ level was higher in RA group than OA group. Similarly, PB $TGF-{\beta}2$ levels of RA and OA groups was not different, but SF $TGF-{\beta}2$ levels was higher in RA group than OA group. 2) In patients with RA, the $TGF-{\beta}1$ levels were higher than $TGF-{\beta}2$ in both the PB and SF, while in patients with OA, there showed higher readings for $TGF-{\beta}1$ than $TGF-{\beta}2$ in SF but no difference between $TGF-{\beta}1$ and $TGF-{\beta}2$ levels in PB. 3) In patients with RA, there were no correlations between PB $TGF-{\beta}1$ and PB $TGF-{\beta}2$ levels, nor between SF $TGF-{\beta}1$ and SF $TGF-{\beta}2$ levels. At the same way, there was no correlation between PB $TGF-{\beta}1$ and SF $TGF-{\beta}1$ levels, nor between each levels of $TGF-{\beta}2$ in patients with RA. 4) There was also no correlation between each $TGF-{\beta}$ isoform and the parameters for disease activity such as ESR, CRP, tender joint count, swollen joint count, rheumatoid factor, and the duration of morning stiffness except between in PB $TGF-{\beta}1$ and disease duration of RA (r=0.637, p<0.01). Conclusion: Each $TGF-{\beta}$ isoforms were higher in synovial fluid of patients with RA than that of patients with OA. The data from the RA patients demonstrated different patterns of expressions of the isoforms depending on which compartment (PB or SF) was investigated. The quantification of different $TGF-{\beta}$ isoform is thought to be important when $TGF-{\beta}$ is measured under disease conditions of RA.

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THE STUDY ON THE EFFECTS OF THE INSULIN-LIKE GROWTH FACTOR-I ON THE BIOLOGICAL ACTIVITY OF THE HUMAN PERIODONTAL LIGAMENT CELLS (Insulin-like growth factor-I 이 치주인대세포의 생물학적 활성도에 미치는 영향에 대한 연구)

  • Kim, Seong-Jin;Lee, Jae-Mok;Suh, Jo-Young
    • Journal of Periodontal and Implant Science
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    • v.24 no.2
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    • pp.219-237
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    • 1994
  • The ultimate goal of clinical periodontal therapy is to achieve regeneration of a healthy connective tissue reattachment. Conventional therapy including scaling, root planing, gingival curettage, gingivectomy and flap procedures of various types results primarily in repair rather than regeneration of the periodontium. In order for periodontal regeneration to occur, progenitor periodontal ligament cells must migrate to the denuded root surface, attach to it, proliferate and mature into an organized and functional fibrous attachment apparatus. Polypeptide growth factors belong to a class of potent biologic mediators which regulate cell differentiation, proliferation, migration and metabolism. Insulin-like growth factor-I (IGF- I ) of these factors appear to have an important role in periodontal wound healing and bone formation. The purpose of this study is to evaluate the effects of IGF- I on the periodontal ligament cells to use as a regeneration promoting agent of periodontal tissue. Human periodontal ligament cells were obtained from periodontal tissue explants culture of the first premolar tooth extracted for the orthodontic treatment. Cells were cultured in Dulbecco's modified Eagle medium(DMEM) with 10% fetal bovine serum. Fourth to seventh passage cells were plated in 24 well tissue culture plates and medium changed to serum-free medium prior to addition of growth factors. Cell proliferation was measured by the incorporation of $[^3H]-thymidine$ into DNA, Protein synthesis was determined by measurement of $[^3H]-proline$ incorporation into collagenase-digestible protein(CDP) and noncollagenous protein(NCP) according to the method of Peterkofsky and Diegelmann (1971), And alkaline phosphatase activity was measured as one parameter of osteoblastic differentiation. The results were as follows : The DNA synthetic activity was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I At the concentration of 10, 100ng/ml, IGF- I significantly increased the DNA synthetic activity(P<0.05) The total protein, collagen and noncollagen synthesis was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I. At the concentration of 1, 10, 100ng/ml, IGF- I significantly increased the total protein, collagen and noncollagen synthesis activity(P<0.95, P<0.001). The % of collagen was not effected according to the concentration of IGF- I. The alkaline phosphatase activity was increased in a dose-, time-dependent manner with IGF- I (10, 100ng/ml). In conclusions, the present study shows that IGF- I has a potentiality to enhance the DNA synthesis of periodontal ligament cells with including the increase of the total protein and collagen synthetic activity. The use of IGF- I to mediate biological stimulation of periodontal ligament cells shows promise for future therapeutic applications.

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Chemoprevention of Helicobacter pylori-associated Gastric Carcinogenesis in a Mouse Model; Is It Possible?

  • Hahm, Ki-Baik;Song, Young-Joon;Oh, Tae-Young;Lee, Jeong-Sang;Surh, Young-Joon;Kim, Young-Bae;Yoo, Byung-Moo;Kim, Jin-Hong;Ha, Sang-Uk;Nahm, Ki-Taik;Kim, Myung-Wook;Kim, Dae-Yong;Cho, Sung-Won
    • BMB Reports
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    • v.36 no.1
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    • pp.82-94
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    • 2003
  • Although debates still exist whether Helicobacter pylori infection is really class I carcinogen or not, H. pylori has been known to provoke precancerous lesions like gastric adenoma and chronic atrophic gastritis with intestinal metaplasia as well as gastric cancer. Chronic persistent, uncontrolled gastric inflammations are possible basis for ensuing gastric carcinogenesis and H. pylori infection increased COX-2 expressions, which might be the one of the mechanisms leading to gastric cancer. To know the implication of long-term treatment of antiinflammatory drugs, rebamipide or nimesulide, on H. pylori-associated gastric carcinogenesis, we infected C57BL/6 mice with H. pylori, especially after MNU administration to promote carcinogenesis and the effects of the long-term administration of rebamipide or nimesulide were evaluated. C57BL/6 mice were sacrificed 50 weeks after H. pylori infection. Colonization rates of H. pylori, degree of gastric inflammation and other pathological changes including atrophic gastritis and metaplasia, serum levels and mRNA transcripts of various mouse cytokines and chemokines, and NF-${\kappa}B$ binding activities, and finally the presence of gastric adenocarcinoma were compared between H. pylori infected group (HP), and H. pylori infected group administered with long-term rebamipide containing pellet diets (HPR) or nimesulide mixed pellets (HPN). Gastric mucosal expressions of ICAM-1, HCAM, MMP, and transcriptional regulations of NF-${\kappa}B$ binding were all significantly decreased in HPR group than in HP group. Multi-probe RNase protection assay showed the significantly decreased mRNA levels of apoptosis related genes and various cytokines genes like IFN-$\gamma$, RANTES, TNF-$\alpha$, TNFR p75, IL-$1{\beta}$ in HPR group. In the experiment designed to provoke gastric cancer through MNU treatment with H. pylori infection, the incidence of gastric carcinoma was not changed between HP and HPR group, but significantly decreased in HPN group, suggesting the chemoprevention of H. pylori-associated gastric carcinogenesis by COX-2 inhibition. Long-term administration of antiinflammatory drugs should be considered in the treatment of H. pylori since they showed the molecular and biologic advantages with possible chemopreventive effect against H. pylori-associated gastric carcinogenesis. If the final concrete proof showing the causal relationship between H. pylori infection and gastric carcinogenesis could be obtained, that will shed new light on chemoprevention of gastric cancer, that is, that gastric/cancer could be prevented through either the eradication of H. pylori or lessening the inflammation provoked by H. pylori infection in high risk group.

Treatment of Early Glassy Cell Carcinoma of Uterine Cervix (초기 자궁경부 유리세포암의 치료)

  • Kim Ok-Bae;Kim Jin-Hee;Choi Tae-Jin
    • Radiation Oncology Journal
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    • v.24 no.2
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    • pp.123-127
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    • 2006
  • Purpose: The purpose of this study was to investigate the clinical findings, treatment, and outcome of patients with glassy cell carcinoma of cervix. Materials and Methods: We reviewed all cases of glassy cell carcinoma of the uterine cervix confirmed and treated at the Dongsan Medical Center, Keimyung University, between January 1993 and December 2005. There were 7 cases with histopathologically confirmed gassy cell carcinoma. A tumor was diagnosed as glassy cell carcinoma if over 50% of the tumor cell type displayed glassy cell features. Six patients with stage IB had radical hysterectomy and bilateral pelvic node dissection, and 2 of them received adjuvant external pelvic irradiation with concurrent chemotherapy. Remaining one patient with stage IIA had curative concurrent chemoradiotherapy with external pelvic irradiation and brachytherapy. Results: There were 7 patients diagnosed as glassy cell carcinoma among the 3,745 (0.2%) patients of carcinoma of uterine cervix. The mean age of 7 patients was 44 years with range of 35 to 53 years of age. The most frequent symptom was vaginal bleeding (86%). By the punch biopsy undertaken before treatment of 7 cases, 2 only cases could diagnose as glassy cell carcinoma of uterine cervix, but remaining of them confirmed by surgical pathological examination. The mean follow up duration was 73 months with range of 13 to 150 months. All 7 patients were alive without disease after treatment. Conclusion: Glassy cell carcinoma of the uterine cervix is a distinct clinicopathologic entity that demonstrates an aggressive biologic behavior. However for early-stage disease, we may have more favorable clinical outcome with radical surgery followed by chemoradiothery.

EGFR, p53, Cox-2 and Bcl-2 Expression in Nasopharyngeal Carcinoma and Their Potential Clinical Implication (비인강암에서 예후인자로서의 EGFR, p53, Cox-2, Bcl-2 단백발현)

  • Chae, Soo-Min;Lee, Youn-Soo;Roh, Kwang-Won;Chung, Su-Mi;Yoon, Sei-Chul;Jang, Hong-Seok;Kim, Yeon-Sil
    • Radiation Oncology Journal
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    • v.25 no.1
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    • pp.43-53
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    • 2007
  • [ $\underline{Purpose}$ ]: To evaluate the relationship between the expression of EGFR, p53, Cox-2, Bcl-2 and the clinical parameters of NPC (nasopharyngeal carcinoma) patients treated with radiotherapy with/without chemotherapy, and to determine if these could be used as a biologic marker. $\underline{Materials\;and\;Methods}$: This study retrospectively examined 75 NPC patients who were pathologically diagnosed at St. Mary's Hospital and Kangnam St Mary's Hospital from March 1988 to August 2002 and treated with radiotherapy with/without chemotherapy. The levels of EGFR, p53, Cox-2, and Bcl-2 expression were determined immunohistochemically. The relationship between the levels of EGFR, p53, Cox-2 and Bcl-2 expression and the H- E staining findings including the WHO classification, TNM stage, tumor response to chemotherapy and radiotherapy, disease free survival (DFS), and overall survival (OS) was analyzed. $\underline{Results}$: At a median follow up of 50.8 months (range: $5.5{\sim}201$ months), the 3 years OS rate and PFS rate were 68.7% and 68.2%, respectively. The five year OS rate and PFS rate were 53.5% and 51.1%, respectively. The median OS duration and PFS duration were 85.5 months and 61.1 months, respectively. The WHO classification correlated with the complete response rate, lymph node metastasis and distant metastasis. The expression of p53 was associated with increased mitosis and poor overall survival. The expression of Bcl-2 correlated with the DFS and WHO classification. The expression of Cox-2 correlated with a poor overall survival and response rate in the lymph node. However, EGFR was not correlated with any factors. $\underline{Conclusion}$: These results suggest that the expression of p53, Cox-2, Bcl-2 plays role in predicting prognostic factors for NPC treated with radiotherapy with/without chemotherapy. However, further study on a larger number of patients will be needed to identify more useful biomarkers of NPC.

DEVELOPMENT OF BIOCOMPATIBLE DRESSING MATERIAL MADE OF COLLAGEN AND AMNIOTIC MEMBRANE AND WOUND HEALING EXPERIMENT IN RAT (양막과 콜라겐을 이용한 생체 적합 드레싱 소재 개발 및 백서 창상치유 실험)

  • Ahn, Kang-Min;Lee, Ji-Ho;Lee, Ui-Lyong;Lee, Jong-Ho;Lee, Jong-Won;Kim, Sung-Po;Yang, Eun-Kyung;Kim, Ki-Ho
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.32 no.3
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    • pp.189-199
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    • 2006
  • Purpose of study: Partial thickness skin graft is the golden standard regimen for full-thickness skin defect caused by burn or trauma. However, in case of extensive burns of more than 50% of total body surface area, the donor site is not sufficient to cover all defects. As a second choice, allograft, xenograft and synthetic materials have been used to treat skin defect. Among them the amniotic membrane(AM) was used as a biological dressing for centuries because of its potential for wound healing. In this study, quantification of EGF in AM and effect of AM-collagen complex on full thickness skin defects was examined. Materials & Methods: The concentration of EGF in fresh, deep frozen and freeze-dried AM was evaluated by ELISA. EGF-R immunostaining was performed in freeze-dried AM. SD rats weighing 250${\sim}$300g was used for wound healing experiment. Three full thickness skin defects(28mm diameter) were made on dorsal surface of SD rat. The control group was covered by Vaselin gauze and AM-collagen complex and $Terudermis^{(R)}$. was grafted in two other defects. Healing area, Cinamon's score were evaluated before biopsy. Grafted sites were retrieved at 3 days, 1 week, 2 weeks and 4 weeks after operation. H & E and Factor VIII immunohistochemical stain was performed to evaluate the microscopic adhesion and structural integrity and microvessel formation. Results: 1. EGF concentration of fresh, deep frozen and freeze-dried AM showed similar level and EGF-R was stained in epithelial layer of freeze-dried AM. 2. At 4 weeks after grafting, the healing area of AM-collagen and Terudermis group was 99.29${\pm}$0.71% and 99.19${\pm}$0.77 of original size. However, that of control group was 24.88${\pm}$2.90. 3. The Cinamon's score of AM-Collagen and $Terudermis^{(R)}$. group at 4 weeks was 15.6${\pm}$1.26 and 14.6${\pm}$3.13 and that of control group was 3.7${\pm}$0.95. Significant difference was observed among control and experimental groups(p<0.05). 4. Histologic examination revealed that AM protected leukocyte infiltration and epithelial migration was nearly completed at 4 weeks. $Terudermis^{(R)}$. group showed mild neutrophil infiltration until 2 weeks and completion of epithelization at 4 weeks. Control group showed massive leukocyte infiltration until 4 weeks. 5. Microvessels were increased sharply at 1 week and control group at 1 and 4 week showed significant differences with $Terudermis^{(R)}$. group of same interval(p<0.05) but no differences were found with AM group(p<0.05). Conclusion: EGF and EGF-R were well preserved in freeze-dried AM. AM attached to collagen acted as excellent biologic dressing which had similar effect with $Terudermis^{(R)}$. AM showed anti-inflammatory action and healing was completed at 4 weeks after full-thickness skin defect.

Effects of Magnetic Resonance Imaging on the Human Body : Analysis of differences according to Dental Implant Material (자기공명영상이 인체에 미치는 영향 : 치아임플란트 재료에 따른 차이 분석)

  • Choe, Dea-yeon;Kim, Dong-Hyun
    • Journal of the Korean Society of Radiology
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    • v.12 no.4
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    • pp.481-489
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    • 2018
  • In MRI examination, when irradiating the human body with RF Pulse to acquire images, the portion of the irradiated RF Pulse energy is absorded into the human body, and this will affect the temperature of the human body. If a metal is inserted into the human body even if the same RF Pulse energy is applied, the SAR value increases and the body temperature changes due to the increase in the electromagnetic wave conductivity of the metal. So we measure and compared with the change in the SAR and temperature in the implant material of the dental implant in Brain MRI examinations. Experiments were performed on a human head model using a 64MHz and 128 MHz RF Pulse frequency generated by a 3.0 Tesla MRI apparatus. And then changed material of dental implants to Titanium and $Al_2O_3$. Using the XFDTD program, the changes in SAR and body temperature around the head were examined. When with Titanium the SAR value and temperature of Brain increased, but with $Al_2O_3$ showed lower SAR and temperature as compared with Titanium. The dental implants were low in SAR and temperature of the head in $Al_2O_3$, which are electrical insulators with low electrical conductivity, compared to Titanium, which is an electrical conductor. It is necessary to study the biologic effect of patient with brain MRI when titanium dental implant material is inserted in the future. Because the maximum value of SAR is much higher than the limit when dental implant material is Titanium. In addition, it is necessary to use an implant of $Al_2O_3$ material to reduce the SAR value and temperature of the Brain in Brain MRI examination.

Effect of Recovery of Pulmonarv Function in Hypothermic Lung Preservation (폐의 저량보존법이 폐기능 회복에 미치는 영향)

  • Lee, Man-Bok;Kim, U-Jong;Gang, Chang-Hui;Lee, Gil-No
    • Journal of Chest Surgery
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    • v.30 no.3
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    • pp.253.1-262
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    • 1997
  • Hypothermia during lung preservation decreases metabolic processes. After the rabbit lung was flushed with modified Euro-Collins solution, heart-lung block was harvested and the left lung was assessed after ligation of the right pulmonary artery and right main-stem bronchus. Heart-lung block was immersed in the same solution for 6 hours. The modified Euro-Collins solution and storage temperature of group 1(10 cases) was 4t, roup 2(10 cases) was l$0^{\circ}C$. On completion of the storage period, the left lung was ventilated and reperfused with blood u:high used a cross-circulating paracorporeal rabbit as a "biologic deoxygenator" for 60 minutes. Pulmonary artery pressure, airway pressure, difference in oxygen tension between mow and outflow perfusate and degree of pulmonary edema were assessed at 10-minute intervals while the left lung was ventilated at 0.8 of the inspired oxygen fraction. The mean pulmonary venous oxygen tensions at 10 and 60 minutes after reperfusion were 209.52$\pm$42.46 and 103.48$\pm$ 15.96 mmHg in group I versus 247.78$\pm$36.19 and 147.91 $\pm$ 11.07 mmHg in group II(p=0.049, (0.0001). The mean alveolar-arterial oxygen differences at 20 and 60 minutes after reperfusion were 357. 95$\pm$ 12.84 and 437.31 14.26 mmHg in group I versus 310.88$\pm$3).47 and )90.93$\pm$ 15.86 mmHg in group II (p=0.0092, (0.0001). The mean pulmonary arterial pressures at 10 and 60 minutes after reperfusion were 40.56$\pm$ 18.66 and 87. 2$\pm$ 17.22 mmHg in group I versus 31.22$\pm$6.84 and 65.78$\pm$ 11.02 mmHg in group rl (p : 0.048, 0.0062). The mean pulmonary vascular resistances at 10 and 60 minutes after reperfusion were 2.69$\pm$0.85 and 4.36$\pm$0.86 mmHg/ml/min in group I versus 1.99$\pm$0.39 and 3.29$\pm$0.55 mmHg/ml/min in group II(p : 0.0323, 0.0062). There were no difference between groups in peak airway pressure, lung compliance and degree of pulmonary edema. In conclusion that preservation of lung at l$0^{\circ}C$ was superior to preservation at 4$^{\circ}C$.}C$.

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Detection of Human Papillomavirus and Expression of p53, c-erbB-2 Protein in Inverted Papilloma of the Nasal Cavity and Paranasal Sinuses (비강 및 부비동의 반전성 유두종에서 인유두종바이러스검출과 p53및 c-erbB-2의 발현)

  • Cho Jae-Shik;Baik Joon;Lim Sang-Chul;Cho Yeon;Yoon Je-Hwan;Seo Duk-Jung;Park Chang-Soo
    • Korean Journal of Head & Neck Oncology
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    • v.17 no.2
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    • pp.162-168
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    • 2001
  • Background: Inverted papilloma(IP) of the nasal cavity and paranasal sinuses is a benign neoplastic condition that can be associated with squamous cell carcinoma (SCC). Several studies have indicated an etiologic role for viruses in the development of inverted papilloma. And it is necessary to find out the significance of a biologic markers such as p53, c-erbB-2 to predict the malignant potential. The purposes of this study are to detect HPV in inverted papilloma of the nasal cavity and paranasal sinus, to examine role of HPV as an etiological agent, to examine the relationship between HPV subtype and malignant transformation of inverted papilloma, and to investigate the relation between expression rate of p53, c-erbB-2 and HPV in recurrent or malignant transformation cases. Material and Methods: Thirty two cases of inverted papilloma(IP) in the nasal cavity and paranasal sinuses were reviewed and classified into 3 groups; simple IP, IP with dysplasia group, IP with squamous cell carcinoma group. Paraffin embedded achival tissue was used in this study. The HPV was detected by in situ hybridzation (ISH) using HPV type 6/11, 16/18, 31/33/35 DNA probes. Expression of p53 and c-erbB-2 was examined by immunohistochemical staining. Results: 1) The HPV was detected in 6(19%) out of 32 cases. 2) The HPV 6/11 was dectected in 4 out of 21 cases of simple IP, HPV 16/18 in 1, HPV 31/33/35 in lout of 8 cases of IP with dysplasia respectively. 3) The positive expression of p53 was 13 cases out of 32 cases; 2 out of 21 cases of simple IP, all of 8 cases of IP with dysplasia and 3 cases of IP with squamous cell carcinoma 4) The positive expression of c-erbB-2 was in 24 out of 32 cases; 16 out of 21 cases of simple IP, 6 out of 8 cases of IP with dysplasia, 2 out of 3 cases of IP with squamous cell ca. 5) The recurrence of IP occurred in lout of 6 cases of positive for HPV, in 4 out of 26 cases negative for HPV. 6) The recurrence of IP occurred only in positive cases for p53. 7) The recurrence of IP occurred in 4(17%) out of 24 cases positive for c-erbB-2, in 1(13%) out of 8 cases negative for c-erbB-2. Conclusion: The p53 expression was associated with Inverted papillomas exhibiting evidence of malignant transformation. Also, there was a correlation between the p53 expression and recurrence.

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Tissue Failure of the Low-Profile lonescu-Shiley Pericardial Valve in Mitral Position (승모판에서의 단고형 이오네스큐판막의 조직실패)

  • 김종환
    • Journal of Chest Surgery
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    • v.30 no.7
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    • pp.670-676
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    • 1997
  • The structural failure of the glutaraldehyde-treated xenograft valves has been the primary concern about the limited durability as predicted from the begimling of clinical use, and long-term follow-up has shown a significant incidence of primary tissue failure(PTF) from both biological and mechanical reasons. Twenty-seven patients with the low-profile lonescu-Shiley valves explanted from mitral position for PTF(Group III) were studied on the patient characteristics and valve pathology, and the results were compared with the matched observations of the Haycock(Group I) and of the standard-profile lonesiu-Shiley valves(Group II). Patients were aged 16 to 56 years(mean, 38.0$\pm$ 11.0 years), and the size of the failed mitral bioprosthesis was 30.8$\pm$ 1.3 mm. The hemodynamic consequences were stenosis in 29.6%, insufficiency in 44.4%, mixed steno-insufficiency in 14.8%, together with normal function for the rest of patients of prophylactic re-replacement. Pathology revealed calcification with or without tissue damage in 63.0% and tissue damage with or without calcification in 58.l%, in contrast with the observations of predominant tissue damage(76.8%) over calcification in Group I and of calcification(76.1%) over tissue damage in group II. Although dystrophic calcification has long and repeatedly dealt with patient's young age as a determinant of valve durability, such a characteristic evidence was not reached even in patients with calcified valves. Moreover, the prolonged explantation p riods from the studied on the previous report suggested strongly yet possibly evolving destructive processes among the valves in the remaining patients, and awaits further follow-up. In conclusion, PTF of the xenograft valves seems to result from more complicated biologic and metabolic reasons as well as more complex mecharical factors than the reported, and newer generation prostheses, with tissue preservation with glutaraldehyde, do not likely to provide decisive improvement in the occurrence of structural failurebioprostheses is generally limited to the highly aged.

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