Daewoo Lee

N-acetyl cysteine inhibits H2O2-mediated reduction in the mineralization of MC3T3-E1 cells by down-regulating Nrf2/HO-1 pathway

There are controversial findings regarding the roles of nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway on bone metabolism under oxidative stress. We investigated how Nrf2/HO-1 pathway affects osteoblast differentiation of MC3T3-E1 cells in response to hydrogen peroxide (H2O2), N-acetyl cysteine (NAC), or both. Exposing the cells to H2O2 decreased the alkaline phosphatase activity, calcium accumulation, and expression of osteoblast markers, such as osteocalcin and runt-related transcription factor-2. In contrast, H2O2 treatment increased the expression of Nrf2 and HO-1 in the cells. Treatment with hemin, a chemical HO-1 inducer, mimicked the inhibitory effect of H2O2 on osteoblast differentiation by increasing the HO-1 expression and decreasing the osteogenic marker genes. Pretreatment with NAC restored all changes induced by H2O2 to near normal levels in the cells. Collectively, our findings suggest that H2O2-mediated activation of Nrf2/HO-1 pathway negatively regulates the osteoblast differentiation, which is inhibited by NAC. [BMB Reports 2015; 48(11): 636-641]

Irradiation inhibits the maturation and mineralization of osteoblasts via the activation of Nrf2/HO-1 pathway.

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates the induction of antioxidant gene expression and protects cells against oxidative injury. However, there are controversial findings regarding the roles of Nrf2 on bone metabolism under oxidative stress. The role of Nrf2 on the differentiation of radiation-exposed osteoblasts is also unclear. We investigated whether Nrf2 negatively or positively affects osteoblast differentiation in response to irradiation. Irradiation inhibited osteoblast differentiation of MC3T3-E1 cells in a dose-dependent manner. This inhibition was evidenced by the irradiation-mediated decreases in bone-like nodule formation, alkaline phosphatase (ALP) activity, calcium accumulation, and expression of osteoblast markers, such as ALP, osteocalcin, osteopontin, bone sialoprotein, osterix, and Runx2. These reductions were accompanied by increased induction of Nrf2 and heme oxygenase-1 (HO-1), accumulation of cellular oxidants, and depletion of antioxidant defense enzymes. siRNA-mediated silencing of Nrf2 markedly reversed the negative effect of irradiation on osteoblast differentiation of the cells, leading to a decrease in HO-1 and an increase in Runx2 levels. Irradiation-mediated decreases in the levels of Runx2 and osteocalcin mRNA, but not of Nrf2 protein, were also significantly inhibited by HO-1 inhibitor, zinc protoporphyrin IX. Furthermore, N-acetyl cysteine restored all of the changes induced by irradiation to near-normal levels in the cells. These results demonstrate that irradiation inhibits osteoblast differentiation and mineralization of MC3T3-E1 cells through the oxidative stress-mediated activation of Nrf2/HO-1 pathway.

The Distribution and Treatment of Outpatients with General Anesthesia in Chonbuk National University Dental Hospital for 9 Years

General anesthesia (GA) for dental care in handicapped patients is necessary to facilitate the provision of safe, efficient, and effective quality treatment. The aims of this study were to determine the anesthetic characteristics of handicapped patients in need of dental treatment in these day care units, and to establish for plan to provide better services. 325 patients who had outpatient general anesthesia from January 2005 to March 2014 were assessed for this study. Patients’distribution and treatment patterns were examined. The proportion of male patients (202, 62.2%) was higher than female patients (123, 37.8%) and the largest group of patients were 5 to 10 years old (85, 26.2%). The reasons for general anesthesia included mental and physical disabilities (207, 63.7%), behavior management (84, 25.8%), parent needs (14, 4.3%), and so on. Restorative treatment was the most common procedure with the average of 4.2 teeth treated per one patient and 43 (13.2%) patients underwent general anesthesia for dental treatment more than once. To expand and improve access to the dental care of the disabled, improvement of the health care system, enhancement of their training for dental care by professionals, and enlarging caregivers’understanding of the importance of oral care in the early stages are required.

Prevalence of Periodontopathogens in Saliva and Plaque of Korean Children and Adolescents

Early colonization of periodontal pathogens has been related as a risk indicator for the subsequent development of periodontal disease. Such colonization can be easily detected with mediums like saliva and plaque. This study aimed to evaluate the prevalence of the bacteria associated with periodontal disease in saliva and plaque in healthy children and adolescents. The experiment was conducted using 90 samples from subjects consisting of thirty elementary school students, thirty high school students and thirty adults. PCR was used to detect the prevalence and distribution of five periodontal pathogens in the collected saliva and plaque. The detected periodontal pathogens are as follows: A. actinomycetemcomitans, P. gingivalis, T. forsythia, F. nucleatum and P. intermedia. Periodontal pathogens were prevailed in a higher number of adolescents than the number of children. A. actinomycetemcomitans and P. intermedia were detected the most in the adolescents group. T. forsythia and F. nucleatum were detected the most in the children group. The overall result showed that saliva is more a useful medium than supragingival plaque. The detection of high risk periodontal pathogens in children and adolescents without clinical signs of periodontal disease can emphasize the importance of the early diagnosis and preventive approach.

Detection of Streptococcus mutans in Saliva using Monoclonal Antibodies

본 연구의 목적은 Streptococcus mutans의 Ag I/II와 glucosyltransferase에 대해 개발된 단일클론항체를 사용한 타액 내 Streptococcus mutans 검출의 효용성을 평가하기 위함이다. 세 군(성인, 미성년자, 그리고 교정치료중인 미성년자)을 대상으로 DMFT,

Anticariogenic Effects of Different Types of Tea

Dentocult^{(R)}

Decompression for Unerupted Primary Mandibular Second Molars Associated with Physical Barriers: Case Reports

-SM strip mutans를 이용한 타액내의 colony density (CFU/mL), polymerase chain reaction을 이용한 Sreptococcus mutans와 Sreptococcus sobrinus의 존재여부, 그리고 4가지 단일클론항체를 사용한 타액 내 Streptococcus mutans 검출 실험을 시행하였다. 그 결과 Streptococcus mutans가 Streptococcus sobrinus보다 치아우식 형성에 더 주요하게 작용한다는 것을 입증하였으며, glucosyltransferases (gtf B, gtf C, gtf D)와 Ag I/II에 대한 단일클론항체들의 Streptococcus mutans를 검출해 내는 능력이

Prevalence and Etiology of Molar Incisor Hypomineralization in Children Aged 8 - 9 Years

Dentocult^{(R)}

Retrospective Study of the Characteristics and Treatment of Odontomas

-SM strip mutans나 polymerase chain reaction을 사용한 검출법보다 뛰어남을 보였다. 【The purpose of this study was to determine the usefulness of a detection method for Streptococcus mutans in saliva with monoclonal antibodies developed targeting Ag I/II and glucosyltransferases (gtf B, gtf C and gtf D) in Streptococcus mutans. In the three groups tested (adults, minors, and minors under orthodontic treatment), the results of the DMFT scores, the colony density (CFU/mL) in their saliva was measured using

Activation of canonical Wnt/β-catenin signaling inhibits H2O2-induced decreases in proliferation and differentiation of human periodontal ligament fibroblasts

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