Hae-Soon Lim

Vitamin D Promotes Odontogenic Differentiation of Human Dental Pulp Cells via ERK Activation.

The active metabolite of vitamin D such as 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) is a well-known key regulatory factor in bone metabolism. However, little is known about the potential of vitamin D as an odontogenic inducer in human dental pulp cells (HDPCs) in vitro. The purpose of this study was to evaluate the effect of vitamin D3 metabolite, 1α,25(OH)2D3, on odontoblastic differentiation in HDPCs. HDPCs extracted from maxillary supernumerary incisors and third molars were directly cultured with 1α,25(OH)2D3 in the absence of differentiation-inducing factors. Treatment of HDPCs with 1α,25(OH)2D3 at a concentration of 10 nM or 100 nM significantly upregulated the expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein1 (DMP1), the odontogenesis-related genes. Also, 1α,25(OH)2D3 enhanced the alkaline phosphatase (ALP) activity and mineralization in HDPCs. In addition, 1α,25(OH)2D3 induced activation of extracellular signal-regulated kinases (ERKs), whereas the ERK inhibitor U0126 ameliorated the upregulation of DSPP and DMP1 and reduced the mineralization enhanced by 1α,25(OH)2D3. These results demonstrated that 1α,25(OH)2D3 promoted odontoblastic differentiation of HDPCs via modulating ERK activation.

Effects of HSP27 downregulation on PDT resistance through PDT-induced autophagy in head and neck cancer cells

We previously reported that photodynamic therapy (PDT) induces cell death in head and neck cancer through both autophagy and apoptosis. Regulation of cell death by autophagy and apoptosis is important to enhance the effects of PDT. Autophagy maintains a balance between cell death and PDT resistance. Downregulation of heat shock protein 27 (HSP27) induces PDT resistance in head and neck cancer cells. Furthermore, HSP70 regulates apoptosis during oxidative stress. However, the role of HSPs in PDT-induced cell death through autophagy and apoptosis is unclear. Therefore, in the present study, we investigated the effects of HSP27 and HSP70 on PDT-induced cell death of oral cancer cells through autophagy and apoptosis. Cancer cells were treated with hematoporphyrin at varying doses, followed by irradiation at 635 nm with an energy density of 5 mW/cm2. We determined the changes in HSP expression by determining the levels of PARP-1 and LC3II in PDT-resistant cells. Furthermore, we assessed cell death signaling after downregulating HSPs by transfecting specific siRNAs. We observed that PDT decreased HSP27 expression but increased HSP70 expression in the head and neck cancer cells. Treatment of cells with LC3II and PARP-1 inhibitors resulted in upregulation of HSP70 and HSP27 expression, respectively. Downregulation of HSP27 and HSP70 induced cell death and PDT resistance through autophagy and apoptosis. Moreover, downregulation of HSP27 in PDT-resistant cells resulted in enhanced survival. These results indicate that the regulation of HSP27 and HSP70 plays a principal role in increasing the effects of PDT by inducing autophagic and apoptotic cell death.

Inhibitory effect of chlorophyllin on the Propionibacterium acnes -induced chemokine expression

Chlorophyllin (CHL), a chlorophyll-derivative, exhibits several beneficial properties, including antibacterial, antioxidant, and anticancer activities. However, its antibacterial and anti-inflammatory activities against Propionibacterium acnes have not been described. The antibacterial activity of this compound was evaluated in vitro using the broth microdilution method. CHL had an inhibitory effect on the growth of P. acnes (MIC = 100 μM). In a real-time reverse transcription-polymerase chain reaction and an enzyme-linked immunosorbent assay, CHL significantly decreased interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) production in a dose-dependent manner, decreasing both mRNA and protein levels for these chemokines in THP-1 cells indicating the anti-inflammatory effects of it. To investigate the molecular mechanisms underlying the anti-inflammatory properties of CHL in THP-1 cells stimulated by P. acnes, we used western blotting to analyze the effect of CHL on activation of the nuclear factor (NF)-κB. CHL inhibited P. acnes-induced IL-8 and MCP-1 production via blockade of NF-κB activation in THP-1 cells. Therefore, based on these results, we suggest that CHL is a useful agent to control the growth of P. acnes involved in acne inflammation and prevent acne.

Analysis of Cariogenic Bacteria in Saliva of Cancer Patients

This study examined salivary flow and salivary pH and the prevalence and levels of cariogenic bacteria in the saliva of oncological patients and healthy controls. Quantitative real-time polymerase chain reaction was used to assess the levels of microbes including Streptococcus mutans, Streptococcus sobrinus, Lactobacillus salivarius, and Lactobacillus acidophilus in the saliva of 41 patients with a solid tumor (SO), 30 patients with a hematologic malignancy (HE), and 40 healthy controls. Salivary flow and pH were lower in oncological patients than in controls. The frequencies of all four cariogenic bacteria were highest in the SO group. S. mutans and L. salivarius were the most commonly detected in all three study groups. Mean numbers of S. sobrinus and L. salivarius in the SO group were significantly higher than in controls (p<0.05). There were no significant differences between patients and controls with respect to mean numbers of S. mutans and L. acidophilus in saliva. However, the proportions of S. mutans, S. sobrinus, and L. salivarius versus total bacteria in the SO group were significantly higher than in controls. Within patients, both mean numbers and the proportions of S. mutans and S. sobrinus were significantly different (p<0.05). In summary, significant differences were found in salivary pH values and the levels of S. mutans, S. sobrinus, and L. salivarius between SO patients and healthy controls.

Diagnostic accuracy and reliability of panoramic temporomandibular joint (TMJ) radiography to detect bony lesions in patients with TMJ osteoarthritis

Background/purpose The value of the temporomandibular joint (TMJ) projections of panoramic radiography for diagnosing TMJ osteoarthritis is not completely elucidated. This study aimed to assess the diagnostic accuracy and reliability of panoramic TMJ radiography to detect bony lesions in patients with TMJ osteoarthritis. Materials and methods This study included 55 TMJs of 44 subjects who were diagnosed with TMJ osteoarthritis. They underwent panoramic radiography (PanRad), lateral (LatTMJ) and frontal (FrnTMJ) projection panoramic TMJ radiography, and cone-beam computed tomography (CBCT). All images were examined by two observers for flattening, erosion, and osteophytes on the condylar head and articular eminence of the TMJ. Results For detecting flattening lesions on the mandibular condyle, the sensitivities of PanRad, LatTMJ, and FrnTMJ were less than 67% and the combination of LatTMJ and FrnTMJ (ComTMJ) had the highest sensitivity for both observers (67.6% and 79.7%, respectively). For erosion lesions, the sensitivity of ComTMJ for observer 1 was the highest, at 84.3%, whereas the specificity of ComTMJ was the lowest, at 37.5%. The sensitivities of all four methods for observer 2 were less than 54% and the specificities ranged from 75.0% to 100%. The overall diagnostic accuracy was highest for ComTMJ (64.3%), followed by LatTMJ (59.5%). The intraobserver reliability was good for one observer and excellent for the other, and the interobserver reliability was fair or moderate. Conclusion Panoramic TMJ radiography demonstrated limited diagnostic accuracy and acceptable reliability in detecting bony lesions of the TMJ, although it was better than conventional panoramic radiography.

Effectiveness of Dental Emergency Education for School Nurses

교내에서 학생들의 치과적 외상은 흔하며 일반교사들보다 보건교사들이 외상의 일차적인 처치를 담당한다. 본 연구는 광주, 전남지역의 초, 중, 고등학교 보건교사들을 대상으로 어린이들의 치아외상시의 대처 방법에 대한 지식수준을 조사하고, 치과 응급처치에 대한 교육을 시행한 후 그 효과가 어느 정도인지를 알아보고...

Repeatability of measurements of surface electromyographic variables during maximum voluntary contraction of temporalis and masseter muscles in normal adults

This study evaluated the intraexaminer repeatability of measurements of surface electromyography (EMG) variables and functional indices of the myoelectric signals from the masseter and temporalis muscles bilaterally in 15 healthy men. The test was repeated on two different days without templates. The resting muscle activity was recorded once, and two kinds of maximum voluntary contraction (MVC) tasks were performed and recorded three times. The two MVC tasks involved clenching the teeth and biting down on two cotton rolls bilaterally with the posterior teeth. The intraclass correlation coefficient (ICC) of amplitude was >88% and that of frequency was >95% during the two MVC tasks but not under resting conditions. The ICC of the asymmetry and activity indices during the two MVC tasks was >76%. A Bland-Altman analysis revealed no significant difference in amplitude or frequency or in the two indices between the two days during the MVC tasks. In conclusion, the measurements of surface EMG variables and the indices obtained according to the study protocol were highly repeatable in healthy men. Additional studies using templates and intraexaminer measurement errors are warranted in both men and women for complete validation of these findings.

Erratum to: Inhibitory effect of chlorophyllin on the Propionibacterium acnes-induced chemokine expression

In the article by Kang et al.