• 대한소아치과학회지
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• 제40권3호
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• pp.177-184
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• 2013

수산화칼슘 근관충전제는 뛰어난 항균작용과 낮은 세포독성으로 우수한 유치 근관충전제로 평가되고 있다. 하지만 수산화칼슘을 근관 내 장기간 적용할 경우 치근 상아질에 미치는 부정적인 영향이 논의되고 있으며 많은 연구에서 영구치 근관에 수산화칼슘을 적용 후 상아질 경도의 감소가 확인되었다. 본 연구에서는 수산화칼슘 제제의 적용 기간에 따라 유치 치근 상아질의 미세경도를 측정하여, 수산화칼슘의 적용이 유치 치근 상아질의 미세경도에 미치는 영향을 평가하고자 하였다. 생리적 치근 흡수가 1/3이상 진행되지 않은 시기에 발거된 60개의 상악 유전치를 각각 20개 씩 대조군, 수산화칼슘과 요오드포름의 혼합제제(Vitapex, Neodent., Japan), 수산화칼슘과 증류수의 혼합제제를 적용하는 3개의 군으로 분류하였다. 각 치아는 같은 과정의 치수 절제술을 시행한 후 교정용 레진에 매몰하여 군당 5개 치아를 배정하고 24시간, 7일, 30일, 90일 후 치근 중앙부에서 2 mm 두께의 시편을 획득하여 비커스 미세경도 측정기를 통해 미세경도를 측정하였다. 측정된 미세경도 값은 Kruskal-Wallis test로 변수 간의 상호관계를 확인하였으며 사후 검정으로 Mann-Whitney test를 시행하였다. 시간에 따른 미세경도 값의 감소량은 선형 회귀분석을 통해 추이를 분석하였다. 수산화칼슘 근관 충전제가 유치의 치근 상아질의 미세경도에 미치는 영향을 조사한 결과, 다음과 같은 결론을 얻을 수 있었다. 수산화칼슘 근관 충전제를 유치의 근관에 적용 시 기간에 따라 치근상아 질의 미세경도가 감소하였으며, 이는 통계적으로 유의하였다(p < 0.05). 수산화칼슘과 요오드화포름의 혼합제제에 비해 수산화칼슘을 증류수에 혼합하여 적용한 경우 유치 치근상아질의 미세경도가 더 급격하게 감소하였으며, 이는 통계적으로 유의하였다(p < 0.05). 수산화칼슘을 적용하지 않은 대조군에서도 7일, 30일, 90일 후 기간에 따라 치근상아질의 미세경도가 감소하였으며, 이는 통계적으로 유의하였다(p < 0.05).

• Journal of Periodontal and Implant Science
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• 제32권3호
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• pp.665-683
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• 2002

A novel glucanhydrolase from a mutant of Lipomyces starkeyi KSM 22 has additional amylase activity besides mutanolytic activity and has been suggested as promising anti-plaque agent. It has been shown effective in hydrolysis of mutan, reduction of mutan formation by Streptococcus mutans and removal pre-formed sucrose-dependent adherent microbial film and has been strongly bound to hydroxyapatitie. These in vitro properties of Lipomyces starkeyi KSM 22 glucanhydrolase are desirable for its application as a dental plaque control agent. In human experimental gingivitis　model and 6 month clinical trial, mouthrinsing with Lipomyces　starkeyi KSM 22 dextranase was comparable to 0.12% chlorhexidine mouthwash in inhibition of plaque accumulation and gingival inflammation and local side effect was negligible. This study was aimed to evaluate the cytotoxic effect of Lipomyces starkeyi KSM 22 glucanhydrolase on human gingival fibroblasts. Primary culture of human gingival fibroblasts at the 4th to 6th passages were used. Glucanhydrolase solution was made from lyophilized glucanhydrolase powder from a mutant of Lipomyces stakeyi KSM 22 solved in PBS and added to DMEM medium to the final concentration of 0.5, 1, and 2 unit. Cells were exposed to glucanhydrolase solution or 0.1 % chlorhexidine and the cells cultured in DMEM with 10% FBS and 1% antibiotics as control. After exposure, the morphological change, cell attachment, and cell activity by MTT assay were evaluated in 0.5, 1.5, 3, 6, 24 hours after treatment. The cell proliferation and cell activity was also evaluated at 2 and 7 days after 1 minute exposure, twice a day. The cell morphology was similar between the Lipomyces smkeyi KSM 22 glucanhydrolase groups and control group during the incubation periods, while most fibroblasts remained as round cell regardless of incubation time in the chlorhexidine group. The numbers of the attached cells in the glucanhydrolase groups were comparable to that of control and significantly higher than the chlorhexidine group. The numbers of the proliferated cells in the glucanhydrolase groups at 7 days of incubation were comparable to the control group and higher than the chlorhexidine group. The cell activity in glucanhydrolase groups paralleled with the increased cell number by attachment and proliferation. According to these results, Lipomyces starkeyj KSM 22 glucanhydrolase has little harmful effect on attachment and proliferation of human gingival fibroblasts, in contrast to 0.1% chlorhexidine which was cytotoxic to human gingival fibroblasts. Therefore this glucanhydrolase preparation is considered as a safe and promising agent for new mouthwash formula in the near future.

• 한국환경보건학회지
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• 제49권4호
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• pp.218-227
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• 2023

Background: Since 2019, the Ministry of Environment has implemented a seasonal fine dust management system from December to March, targeting high PM_2.5 levels with the aim of reducing PM_2.5 concentrations and protecting public health. The focus of improving the seasonal management system lies in the atmospheric PM_2.5 levels. Considering the primary goal of protecting public health, it is necessary to analyze the policy effects from an exposure perspective rather than a concentration-based approach. Objectives: This study aims to quantitatively assess the improvement of indoor PM_2.5 levels and the health impacts of the seasonal management system by comparing the periods before and during its implementation in residential environments. Methods: PM_2.5 concentrations within residential environments in a metropolitan area were measured using an optical particle counter (IAQ-C7, K-weather, Ltd, Korea) at one-minute intervals during the pre-implementation period (November 21~25, 2022) and during the implementation period (December 19~23, 2022). Based on the measured PM_2.5 concentrations, a quantitative evaluation of cancer and mortality risks was conducted according to age and gender. Results: The results of comparing indoor and outdoor PM_2.5 concentrations before and during the implementation of the seasonal management system showed a decrease of approximately 56.6% and 47.9%, respectively. Health risk assessments revealed that both the safety-limit-based and safety-target-based Hazard Quotients (HQ) exceeded the threshold of 0.1 for children under 19 years of age, both before and after the implementation. The mortality risk decreased by approximately 47.9% after the implementation, with children aged 0-9 showing the highest mortality risk at 0.9%. Conclusions: The findings of this study confirmed the positive health impacts of the seasonal management system across all age groups, particularly children under 19 who are more vulnerable to fine dust exposure.

• 한국환경보건학회지
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• 제20권2호
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• pp.64-72
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• 1994

Tolerance to toxic effects of cadmium (Cd), including lethality has been shown following pretreatment with cadmium and zinc. This study was designed to determine if tolerance also develops to Cd-induced hepatotoxicity and renal toxicity. Three groups of rats (A, B, C), each consisting of 108 rats, were studied and each group was divided into three subgroups (1, 2, 3), 12 rats for each subgroup. Rats were subcutaneously pretreated with saline (A), CdCl$_2$ (0.5 mg/kg, B), and ZnCl$_2$ (13.0 mg/kg, C) during time periods of 5 days. At the end of the period, rats were challenged with CdCIa (3.0 and 6.0 mg/kg) by intraperitoneal injection. As for the cadmium levels in rat tissues after pretreatments, it was highest in the liver. Then kidney, heart, blood and muscle followed it in that order. After 24, 48 and 96 hours of intraperitoneal injection by challenge doses the concentration of cadmium in liver and kidney increased proportionally to the increase of challenge dosage. However metallothioneins in liver and kidney were increased by the pretreatment of cadmium and zinc. These data indicate the liver is a major target organ of acute Cd poisoning, and suggest that cadmium induced hepatic injury, via release of Cd-MT, may play and important role in the nephrotoxicity observed in response to short-term exposure to cadmium. This result suggests that increasing cadmium concentrations, gradually accumulating in liver and kidney as the result of the pretteatmerit, served to induced the synthesis of metallothionein, thus making them resistant to the challenge from cadmium.

• 한국환경보건학회지
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• 제21권3호
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• pp.1-15
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• 1995

Tolerance to toxic effects of cadmium(Cd), including lethality has been shown following pretreatment with cadmium and zinc. This study was designed to determine if tolerance also develops to Cd-induced hepatotoxicity and renal toxicity. Three groups of rats(A, B, C), each consisting of 52 rats, were studied and each group was divided into three subgroups(1,2,3), 28 rats for each subgroup. Rats were subcutaneously pretreated with saline(A), $CdCl_2$(0.5 mg/kg, B), and $ZnCl_2$(13.0 mg/kg, C) during time periods of 5 days. At the end of the period, rats were challenged with $CdCl_2$(3.0 and 6.0 mg/kg) by intraperitoneal injection. As for the cadmium levels in rat tissues after 1,3,5,6 days of pretreatments, it was highest in the liver. Then kidney, heart, blood and muscle followed it in that order. After 24, 48 and 96 hours of intraperitoneal injection by challenge doses the concentration of cadmium in liver and kidney increased proportionally to the increase of challenge dosage. However metallothioneins in liver and kidney were increased by the pretreatment of cadmium and zinc. These data indicate the liver is a major target-organ of acute Cd poisoning, and suggest that cadmium induced hepatic injury, via release of Cd-MT, may play an important role in the nephrotoxicity observed in response to short-term exposure to cadmium. This result suggest that increasing cadmium concentrations, gradually accumulating in liver and kidney as the result of the pretreatment, served to induce the synthesis of metallothionein, thus making them resistant to the challenge from cadmium.

• 대한전자공학회논문지TC
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• 제47권1호
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• pp.53-57
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• 2010

본 논문은 기존의 방사선 피폭량을 실시간으로 산출하는 배터리 내장형 유선 혹은 RF형 선량계가 있었지만, 배터리를 제거하여 무전력으로 구동하는 알고리즘을 제안하고자 한다. 유선형 선량계의 경우, 유지 및 관리가 주기적으로 필요하다는 단점이 있다. 또한 배터리가 내장된 RF형 선량계의 경우에는 그 크기가 크고 배터리의 교체 등이 요구되고 있다. 특히 RF형 선량계는 큰 전력 소모량으로 인해 구현하기에는 많은 전력이 필요하다는 문제점을 가지고 있다. 본 논문은 저전력으로 구동하기 위한 방안으로써 마이크로컨트롤러의 동작 클럭을 낮추고, 정류기의 효율을 개선되도록 설계하였다. 또한 외부메모리 및 DC/DC 컨버터를 제거하여 선량계 회로의 간소화를 하였다. 이러한 연구는 회로의 간소화 및 소형화하는데 도움을 줄 수 있을 뿐만 아니라 무전원 비접촉형 선량계의 설계 및 응용기술에 많은 영향을 줄 수 있을 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.87-94
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• 2018

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at $22^{\circ}C$ and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.6.1-6.8
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• 2016

Background: Intravenous bisphosphonates have been used in metastatic breast cancer patients to reduce pathologic bone fracture and bone pain. However, necrosis of the jaw has been reported in those who received intravenous bisphosphonates. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is caused by dental extraction, dental implant surgery, and denture wearing; however, it occurs spontaneously. The purpose of this study was to report BRONJ in metastatic breast cancer patients. Methods: Consecutive 25 female patients were referred from the Department of Oncology from 2008 to 2014 for jaw bone discomfort. Staging of breast cancer, history of bisphosphonate infusion, etiology of BRONJ, and treatment results were reviewed. Average age of the patients was 55.4 years old (38-74). Twelve maxillae and 16 mandibles were involved. Conservative treatments such as irrigation, antibiotic medication, analgesics, and oral gargle were applied for all patients for the initial treatment. Patients who had sequestrum underwent debridement and primary closure. Results: The etiologies of BRONJ were dental extraction (19 cases), dental implant (2 cases), and endodontic treatment (1 case). However, three patients did not have any risk factors to cause BRONJ. Three patients died of progression of metastasis during follow-up periods. Surgical debridement was performed in 21 patients with success in 18 patients. Three patients showed recurred bone exposure and infection after operation. Conclusions: Prevention of the BRONJ is critical in metastatic breast cancer patients. Conservative treatment to reduce pain, discomfort, and infection is recommended for the initial therapy. However, if there is a sequestrum, surgical debridement and primary closure is the key to treat the BRONJ.

• 한국안전학회지
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• 제21권3호
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• pp.53-58
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• 2006

Following a Mediterranean fruit fly outbreak in South Australia, a bait spray program involving the pesticides like malathion(MAL) was carried out. During the application, dermal exposure was considered for the pest controllers wearing PVC gloves. However there is a lack of information about PVC glove performance like break through times and permeation rates with MAL, therefore, a new analytical method for HPLC-UV was developed. A standard permeation test cell was used in this study. From the results of this study, more than 96% solubility of MAL was provided at 30% isopropyl alcohol in distilled water as a collecting media. However, there was significant decomposition of MAL when the solutions were kept at over $50^{\circ}C$ for 2-3 hours. As a mobile phase, 50% acetonitrile water solution (pH 6.0) gave the greater sensitivity compared with other compositions of acetonitrile solution. The arm section of the gloves had shorter breakthrough times and higher permeation rates compared with the palm. There was no malathion solution breakthrough up to 24 hours using the 1% MAL working strength solution. When the temperature was changed from $22{\pm}1^{\circ}C\;to\;37{\pm}1^{\circ}C$, the breakthrough times were decreased by 14.5% on palm and 37.5% on arm, and permeation rates were increased significantly. The findings of this study indicate that further investigations on used gloves, periods of use and varying working conditions like tasks and seasons should be carried out to assess potential worst case scenarios.

• Pediatric Infection and Vaccine
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• 제18권1호
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• pp.97-102
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• 2011

Acinetobactor baumanii 는 기회 감염균으로 carbapenem의 사용이 증가하면서 MDRAB와 같은 내성균으로 출현하고 있다. 저자들은 경희의료원에서 carbapenem을 투약받지 않았더라도 집중치료실에 장기간 입원하여 기관삽관과 인공호흡기 치료를 받거나 침습적인 수술을 받아 도관을 유지하는 환아에서 MDRAB가 동정되었다는 것을 확인하였다. carbapenem을 사용하지 않았더라도 장기간 집중치료실에 입원할 것으로 예상되는 환자들에게 원내전파를 통한 감염을 최소화하기 위하여 원내감염관리에 최선을 다해야 할 것이기에 이상의 증례를 통하여 보고한다.