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Effects of Calcium Citrate Isolated from Oyster Shell on Papain-induced Osteoarthritis in C57BL/6J Mice (굴 패각 구연산칼슘이 Papain으로 유도된 골관절염 C57BL/6J Mice에 미치는 영향)

  • Choi, Eun-Young;Kim, Hak-Ju;Han, Ji-Sook
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.10
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    • pp.1510-1518
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    • 2014
  • This study investigated the effects of calcium citrate on papain-induced osteoarthritis in C57BL/6J mice. Osteoarthritis was induced by injecting $6{\mu}L$ of papain into the knee joints of mice. Calcium citrate was made by crushing the centrifuged precipitate after reacting 0.5 M citric acid with 1 kg of oyster shell extract. The mice were divided into five groups (n=8). The normal group was untreated, whereas the papain group was induced to have osteoarthritis and treated with $200{\mu}L$ of water per day. The papain+DS group was treated with diclofenac sodium. The papain+calcium citrate groups were treated with calcium citrate at 150 and 300 mg/kg/bw for 28 days. Proteoglycan contents in articular cartilages were measured by safranin O/fast green staining and hematoxylin & eosin staining. Histopathological changes in cartilages were analyzed by the Rudolphi score approach. Contents of pro-inflammatory cytokines including TNF-${\alpha}$, IL-$1{\beta}$ and IL-6 in plasma, were measured by the ELISA method. Body weights among the treated groups were not significantly different compared with that of the normal group. Cartilage loss and joint instability in the calcium citrate group improved significantly (P<0.05) in a dose-dependent manner compared with the papain group. Further, proteoglycan content of the calcium citrate group was considerably (P<0.05) higher than that of the papain group. Osteoarthritis scores in the calcium citrate group were considerably (P<0.05) reduced compared with the papain group. In the group treated with calcium citrate, contents of TNF-${\alpha}$, IL-$1{\beta}$ and IL-6 in plasma were significantly (P<0.05) reduced in a dose-dependent manner in comparison with the normal group. Based on these results, we suggest that calcium citrate is effective for treatment of osteoarthritis.

Treatment of Mycobacterium avium Complex (MAC) Pulmonary Disease (Mycobacterium avium Complex (MAC) 폐질환의 치료성적)

  • Koh, Won-Jung;Kwon, O Jung;Kang, Eun Hae;Suh, Gee Young;Chung, Man Pyo;Kim, Hojoong;Chung, Myung Jin;Kim, Tae Sung;Lee, Kyung Soo;Lee, Nam Yong;Park, Young Kil;Bai, Gill Han
    • Tuberculosis and Respiratory Diseases
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    • v.57 no.3
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    • pp.234-241
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    • 2004
  • Background : There has been a gradual increase in the number of newly diagnosed cases of Mycobacterium avium complex (MAC) pulmonary disease. However, the optimal therapeutic regimen for the disease has not yet established and there is no report about the treatment outcome of MAC pulmonary disease in Korea. This study examined the effect of clarithromycin-based regimen in patients with pulmonary MAC disease without a HIV infection. Materials and Methods : Fifty-six patients with pulmonary MAC disease were diagnosed according to the American Thoracic Society criteria from January 2000 to December 2003 at this hospital. Of these patients, 15 were treated with clarithromycin, rifampin, and ethambutol for more than 6 months, together with streptomycin initially (first 6 months) in 8 patients. Results : Six months after the treatment, the sputum cultures converted from positive to negative in 8 patients (53%) and the radiological findings improved in 10 (67%). At 12 months 4 patients (44%) achieved sputum negative conversion and 6 patients out of 9 patients (67%) who were treated for more than 12 months showed radiological improvement. Overall, the sputum findings converted to negative in nine patients (60%) who underwent medical treatment. A pulmonary resection was successfully performed in one patient. Only one patient discontinued the treatment due to side effects such as gastrointestinal intolerance and optic neuritis. Conclusion : A combined regimen containing clarithromycin is relatively safe and tolerable even in the elderly outpatients. However, the results of this combined chemotherapy were unsatisfactory and new companion drugs for MAC pulmonary disease are needed. A resection may be considered for localized disease.

Hypoxia Inducible Factor-1α Directly Regulates Nuclear Clusterin Transcription by Interacting with Hypoxia Response Elements in the Clusterin Promoter

  • Park, Jeongsook;Park, So Yun;Shin, Eunkyung;Lee, Sun Hee;Kim, Yoon Sook;Lee, Dong Hoon;Roh, Gu Seob;Kim, Hyun Joon;Kang, Sang Soo;Cho, Gyeong Jae;Jeong, Bo-Young;Kim, Hwajin;Choi, Wan Sung
    • Molecules and Cells
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    • v.37 no.2
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    • pp.178-186
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    • 2014
  • Differential transcription of the clusterin (CLU) gene yields two CLU isoforms, a nuclear form (nCLU) and a secretory form (sCLU), which play crucial roles in prostate tumorigenesis. Pro-apoptotic nCLU and anti-apoptotic sCLU have opposite effects and are differentially expressed in normal and cancer cells; however, their regulatory mechanisms at the transcriptional level are not yet known. Here, we examined the transcriptional regulation of nCLU in response to hypoxia. We identified three putative hypoxia response elements (HREs) in the human CLU promoter between positions -806 and +51 bp. Using a luciferase reporter, electrophoretic gel mobility shift, and chromatin immunoprecipitation assays, we further showed that hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$) bound directly to these sites and activated transcription. Exposure to the hypoxia-mimetic compound $CoCl_2$, incubation under 1% $O_2$ conditions, or overexpression of HIF-$1{\alpha}$ enhanced nCLU expression and induced apoptosis in human prostate cancer PC3M cells. However, LNCaP prostate cancer cells were resistant to hypoxia-induced cell death. Methylation-specific PCR analysis revealed that the CLU promoter in PC3M cells was not methylated; in contrast, the CLU promoter in LNCap cells was methylated. Co-treatment of LNCaP cells with $CoCl_2$ and a demethylating agent promoted apoptotic cell death through the induction of nCLU. We conclude that nCLU expression is regulated by direct binding of HIF-$1{\alpha}$ to HRE sites and is epigenetically controlled by methylation of its promoter region.

Role of the Nuclear Transcription Factor NF-κB Caused by Acute Hypoxia in the Heart (급성 저산소증 상태에서 심장 내 전사인자 NF-κB의 기능)

  • Joo, Chan Uhng;Juhng, Woo Suk;Kim, Jae Cheol;Yi, Ho Keun
    • Clinical and Experimental Pediatrics
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    • v.45 no.9
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    • pp.1106-1113
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    • 2002
  • Purpose : Nuclear ($factor-{\kappa}BNF-{\kappa}B$) is now recognized as playing a potential role in programmed cell death and the adaptive response to various stress. Cellular hypoxia is a primary manifestation of many cardiovascular diseases. It seems that vascular endothelial growth factor (VEGF) and insulin like growth factor-I(IGF-I) have a function as a protective molecule in the heart against several stress including hypoxia. In this study, the role of $NF-{\kappa}B$ to the cellular response and regulation of protective molecules against the acute hypoxia in the heart was studied. Methods : To cause acute hypoxic stress to the heart, Sprague Dawley rats were exposed to hypoxic chamer($N_2$ 92% and $O_2$ 8%). After the hypoxic exposure, nuclear proteins, total proteins and mRNA were isolated from heart. Translocation of the transcription factors $NF-{\kappa}B$, NF-ATc, AP-1 and NKX-2.5 were evaluated by electrophoretic mobility shift assay(EMSA). The expression of IGF-I and VEGF were studied before and after the hypoxic stress by competitive-PCR, Northern hybridization and Western hybridization. To confirm the role of the $NF-{\kappa}B$ in the heart, the rats also were pretreated with diethyl-dithiocarbamic acid(DDTC) into peritoneal cavity to block $NF-{\kappa}B$ translocation into nucleus. Results : The expression of $NF-{\kappa}B$, AP-1 and NF-ATc were increased by the hypoxic stress. Increased expression of the VEGF and IGF-I were also observed by the hypoxic stress. However, the blocking of the $NF-{\kappa}B$ translocation reduced those expressions of VEGF and IGF-I. Conclusion : These results suggest that $NF-{\kappa}B$ has a protective role against the acute hypoxia through several gene expression, especially VEGF and IGF-I in heart muscle.

Evaluation of Hemodynamic Failure with Acetazolamide Challenged $^{123}I-IMP$ Brain SEPCT and PET (PET과 Acetazolamide 부하 $^{123}I-IMP$ 뇌혈류 SPECT를 이용한 혈역학적 부전의 평가)

  • Chun, Kyung-Ah;Cho, In-Ho;Won, Kyu-Jang;Lee, Hyung-Woo;Hayashida, Kohei
    • The Korean Journal of Nuclear Medicine
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    • v.37 no.2
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    • pp.94-102
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    • 2003
  • Purpose : Cerebral blood flow (CBF) reactivity to acetazolamide (ACZ) is useful to select patients with hemodynamic failure. However, it is still a matter of speculation that varying degrees of regional CBF increases after ACZ administration represent the severity or stage of regional hemodynamic failure as assessed by positron emission tomography (PET). We studied to elucidate whether ACZ challenge $^{123}I-IMP$ brain single photon emission tomography (SPECT) can accurately grade the seventy of regional hemodynamic failure. Materials and Methods: Eighteen patients (M: 16, F: 2, average age: 61 years) with unilateral occlusive disease of the internal carotid artery or the trunk of the middle cerebral artery (MCA). Patients undewent $^{123}I-IMP$ brain SPECT study with acetazolamide challenge and PET study was carried out within 2 weeks before and after SPECT study. Five healthy volunteers with a mean age of 48 years (range: 28-73 yr, M: 3, F: 2) underwent PET studies to determine normal values. In SPECT study, an asymmetry index (Al)-the percentage of radioactivity of region of interest (ROI) in the occlusive cerebrovascular lesion to the contralateral homologous ROI-was used for numerical evaluation of relative $^{123}I-IMP$ distribution. In PET study, regional CBF, oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen ($CMRO_2$) and cerebral blood volume (CBV) values were measured with $^{15}O-labeled$ gas inhalation method and the values were used for comparison with Al (Al during acetazolamide challenge-Al of basal study) on the SPECT study. ROls were classified by severity into three groups (normal, stage I and stage II). Results: Mean values of Al in areas with normal, stage I and stage II hemodynamic failure were $6.25{\pm}7.77%\;(n=107),\;-10.38{\pm}10.41%\:(n=117)\;and\;13.30{\pm}10.51%\;(n=140)$, respectively. Al significantly differed with each groups (p<0.05). Correlation between Al and CBF, OEF and CBV/CBF in hemisphere with occlusive cerebrovascular lesion was 0.20 (p<0.01), -0.28 (p<0.01) and -0.28 (p<0.01), respectively. Conclusion: We concluded that $^{123}I-IMP$ brain SPECT with acetazolamide challenge could determine the severity ad stage of regional hemodynamic failure as assessed by PET.

Anti-inflammatory Activity of Crinum asiaticum Linne var. Japonicum Extract and its Application as a Cosmeceutical Ingredient (문주란의 항염효과와 화장료적 특성)

  • Kim, Ki-Ho;Kim, Young-Heui;Kim, Ki-Soo;Park, Sun-Hee;Lee, Soo-Hee;Kim, Young-Jin;Kim, Young-Sil;Kim, Jong-Heon
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.32 no.1 s.55
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    • pp.59-64
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    • 2006
  • Crinum asiaticum Linne var. japonicum has long been used as a rheumatic remedy, an anti-pyretic, an anti-ulcer treatment, and for the alleviation of local pain and fever in Korea and Malaysia. In order to investigate the possibility of Crinum asiaticum Linne var. japonicum extract as a cosmetic ingredient, we measured its anti-inflammatory effect by inhibition of iNOS (inducible nitric oxide synthase), and the release of PGE2, IL-6, and IL-8. HPLC experiment after extraction with 95% ethanol at pH 3.5 showed that Crinum asiaticum Linne var. japonicum was mainly composed of lycorine (up to 1%), a well-known immunosuppressant. The content of lycorine varied depending on the type of tissue analyzed and the extraction method. In anti-inflammatory assay for inhibition of nitric oxide formation on lipopolysaccharide (LPS)- activated mouse macrophage RAW 264.7 cells, the ethanolic extract of Crinum asiaticum showed inhibitory activity of NO production in dose-dependent manner ($IC_{50} = 83.5 {\mu}g/mL$). Additional study by RT-PCR demonstrated that the extract of Crinum asiaticum significantly suppressed the expression of the iNOS gene. Moreover, the extract of Crinum asiaticum did not show my cytotoxicity, but did show cell proliferation effect against LPS ($10{\sim}60%$ increase of tell viability). In an assay to determine inhibition of the $H_2O_2$-activated release of PGE2, IL-6, and IL-8 in human normal fibroblast cell lines, the release of PGE2 and IL-6 was almost completely inhibited above concentrations of 0.05% and 1%, respectively. Moreover, the release of IL-8 was completely inhibited over the entire range of concentrations (> 0.0025%). The result showed that the extract of Crinum asiaticum Linne var. japonicum has sufficient anti-inflammatory effect. There-fore, Crinum asiaticum Linne var. japonicum extract may be useful as an ingredient of cosmetic products.

A study on the state of inservice education for dental hygienists and their relevant awareness (치과위생사의 보수교육 실태 및 인식에 관한 연구)

  • Jung, Jae-Yeon;Kim, Kyung-Mi;Cho, Myung-Sook;Ahn, Geum-Sun;Song, Kyoung-Hee;Choi, Hye-Jung;Choi, Youn-Seon;Hwang, Yoon-Sook
    • Journal of Korean society of Dental Hygiene
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    • v.7 no.1
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    • pp.73-89
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    • 2007
  • The purpose of this study was to examine the reality of inservice education provided to members of Korean Dental Hygienists Association, the state of relevant academic conferences, and the perception of the members about inservice education and academic conference. It's basically meant to help boost their participation in inservice education and their satisfaction with it, and to show some of the right directions for that. The subjects in this study were dental hygienists who attended a symposium on July 1, 2006. After a survey was conducted, the answer sheets from 489 participants were analyzed, and the findings of the study were as follows: 1. General hospitals and university hospitals made up the largest group(91.4%) that gave a monthly leave of absence, and the second largest group was dental hospitals(75.4%), followed by dental clinics(58.3%) and public dental clinics(48.0%). The most common closing time in dental clinics and dental hospitals was 5 p.m., and that was 12 p.m. in general hospitals and university hospitals. The dental hygienists in public dental clinics didn't work on Saturdays. By type of workplace, treatment was the most common duty for the dental hygienists in dental clinics and dental hospitals to perform, and those who worked at general hospitals, university hospitals and public health clinics were in charge of extensive range of jobs. 2. The rates of the dental hygienists who took that education stood at 94.9% in public dental clinics, 78.7% in dental hospitals and 75.3% in dental clinics, general hospitals and university hospitals. Regarding how many marks they got on an yearly basis, those who got eight marks or more made up the largest group(55.6%), followed by four marks or more(11.8%), six marks or more(3.4%), and two marks or more(1.5%). As for the usefulness of inservice education for their job performance, the largest number of the dental hygienists(40.8%) found it to be helpful, and the second greatest group(37.5%) considered its effectiveness to be so-so. The third largest group(8.4%) found it to be of great use, and the fourth biggest group(4.2%) considered it to be of no service. The fifth biggest group(l.3%) thought it was absolutely useless. By type of workplace, the workers in dental clinics, dental hospitals, general hospitals and university hospitals wanted the most to learn how to take care of clinical work(acquisition of up-to-date technology), and those in public health clinics hoped the most to learn about public dental health. By type of workplace, the workers in dental clinics had their sight set on self-development the most, and the dental hygienists in dental hospitals, general hospitals, university hospitals and public health clinics were most in pursuit of acquiring new knowledge. By type of workplace, the specific given conditions at work were most singled out by the dental clinic workers as the reason, and the dental hospital employees pointed out time constraints the most. The dental hygienists in general hospitals and university hospitals cited time constraints and financial burden the most, and the public health clinic personnels mentioned inaccessibility of a place for inservice education as the reason. 3. The public health clinic workers participated in academic conferences the most(90.8%), followed by the general and university hospital personnels(68.8%), dental hospital employees(65.6%) and dental clinic workers(65.5%). By type of workplace, the public health clinic workers(73.5%) expressed the most satisfaction, followed by the general and university hospital employees(67.7%), dental clinic workers(62.3%) and dental hospital personnels(54.1%). By type of workplace, the employees of dental clinics, dental hospitals, general hospitals and university hospitals preferred Saturdays, and the public health clinic workers had a liking for weekdays. As for a favored place, hotels were most preferred, followed by university hospitals, general hospitals, college lecture rooms, district halls and local public institutions. Hotels were most favored regardless of the type of workplace. 4. Regarding outlook on inservice education, they had the highest opinion on the facilities and given conditions of lecture rooms($3.41{\pm}0.83$), followed by the professionalism of lecturers($3.34{\pm}0.83$), procedures of receipt and attendance confirmation($3.34{\pm}0.83$) and class size($3.13{\pm}0.89$). On the contrary, they took the most dismal view of the inaccessibility of a place of inservice education($2.08{\pm}0.92$), followed by limited opportunity and limited date for that education($2.51{\pm}0.99$), extra financial burden($2.53{\pm}1.18$) and high tuition fee($2.57{\pm}0.96$).

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Usefulness of Blood Pool Half Body in Three Phase Bone Scan in Patients with R/O Reflex Symphathetic Dystrophy Syndrome (반사성교감신경 이영양증후군 환자의 삼상 골 스캔 시 Half Body 혈액 풀 영상의 적용)

  • Lee, Moo-Seok;Lee, Hyo-Yeong;Yun, Jong-Jun;Lee, Hwa-Jin;Song, Hyeon-Seok;Park, Se-Yun;Jeong, Ji-Uk
    • The Korean Journal of Nuclear Medicine Technology
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    • v.14 no.1
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    • pp.105-110
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    • 2010
  • Purpose: Three phase bone scan was considered sensitive in Patients with Reflex Symphathetic Dystrophy Syndrome (RSDS). Generally, three phase bone scan in the RSDS patients shows increased uptake of one side extremity joint. But three phase bone scan has been performed with flow, blood pool and delayed scan. We performed blood pool half body scan in order to investigate its usefulness. Materials and Methods: From October 2007 to September 2009, three phase bone scan (flow, blood pool, half body blood pool, delayed) was performed after injection of 750 MBq of $^{99m}Tc$-DPD in diagnosed patients with RSDS (M:F=8:7, R:L=9:6). For quantitative analysis, we obtained the count ratios of bilateral hands by drawing a region of interest (ROI) in the three phase images and compared with the count ratios of shoulders in half body blood pool and delayed images. Results: In flow images, right/left ratios were $1.09{\pm}0.53$. In blood pool images, right/left ratios were $1.13{\pm}0.47$ (hand), $1.08{\pm}0.26$ (shoulder). In delayed images, right/left ratios were $1.24{\pm}0.75$ (hand), $1.11{\pm}0.31$ (shoulder). As a result, Log of right/left counts of the others and that of shoulder blood pool image were correlated well with statistical significance (Spearman's R, p<0.005 SPSS for windows ver.12.0). Conclusion: Half body blood pool scan may be helpful in the diagnosis of patients with RSDS. Moreover, Half body blood pool scan reduced false negative and false positive rates. In order to improve agreement on interpretation of RSDS, Blood pool half body scan should be established as common criteria.

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Effects of Matrix Metalloproteinase Inhibitor on Ventilator-Induced Lung Injury in Rats (기계환기로 인한 백서의 급성 폐손상에서 Matrix Metalloproteinase Inhibitor의 효과)

  • Kim, Je-Hyeong;Park, Soo-Yeon;Hur, Gyu-Young;Lee, Seung-Heon;Lee, Sang-Yeub;Park, Sang-Myeon;Suh, In-Bum;Shin, Chol;Shim, Jae-Jeong;In, Kwang-Ho;Kang, Kyung-Ho;Yoo, Se-Hwa
    • Tuberculosis and Respiratory Diseases
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    • v.53 no.6
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    • pp.619-634
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    • 2002
  • Background : Many inflammatory mediators and collagenases are involved in the pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The increase of matrix metalloproteinase-9 (MMP-9, gelatinase-B) produced mainly by inflammatory cells was reported in many ALI models and connective tissue cells. In this study, the expression of MMP-9 in ventilator-induced lung injury (VILI) model and the effects of matrix metalloproteinase inhibitor (MMPI) on VILI were investigated. Methods : Eighteen Sprague-Dawley rats were divided into three groups: low tidal Volume (LVT, 7mL/Kg tidal volume, 3 $cmH_2O$ PEEP, 40/min), high tidal volume (HVT, 30mL/Kg tidal volume, no PEEP, 40/min) and high tidal volume with MMPI (HVT+MMPI) groups. Mechanical ventilation was performed in room air for 2 hours. The 20 mg/Kg of CMT-3 (chemically modified tetracycline-3, 6-demethyl 6-deoxy 4-dedimethylamino tetracycline) was gavaged as MMPI from three days before mechanical ventilation. The degree of lung injury was measured with wet-to-dry weight ratio and acute lung injury score. Expression of MMP-9 was studied by immunohistochemical stain with a mouse monoclonal anti-rat MMP-9 $IgG_1$. Results : In the LVT, HVT and HVT+MMPI groups, the wet-to-dry weight ratio was $4.70{\pm}0.14$, $6.82{\pm}1.28$ and $4.92{\pm}0.98$, respectively. In the HVT group, the ratio was significantly higher than other groups (p<0.05). Acute lung injury score measured by five-point scale was $3.25{\pm}1.17$, $12.83{\pm}1.17$ and $4.67{\pm}0.52$, respectively. The HVT group was significantly damaged by VILI and MMPI protects injuries by mechanical ventilation (p<0.05). Expression of MMP-9 measured by four-point scale was $3.33{\pm}2.07$, $12.17{\pm}2.79$ and $3.60{\pm}1.95$, respectively, which were significantly higher in the HVT group (p<0.05). Conclusion : VILI increases significantly the expression of MMP-9 and MMPI prevents lung injury induced by mechanical ventilation through the inhibition of MMP-9.

A STUDY OF THE MECHANISM OF IMPROVING ACID RESISTANCE OF BOVINE TOOTH ENAMEL AFTER PULSED Nd-YAG LASER IRRADIATION (펄스형 Nd-YAG 레이저 조사에 의한 법랑질 내산성 증가 기전에 관한 연구)

  • Lee, Young-Soon;Shon, Heung-Kyu
    • Journal of the korean academy of Pediatric Dentistry
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    • v.23 no.3
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    • pp.640-658
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    • 1996
  • The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

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