Byung-Gook Kim

LY294002 inhibits monocyte chemoattractant protein-1 expression through a phosphatidylinositol 3-kinase-independent mechanism

The effects of LY294002 (LY29) and wortmannin (WM), inhibitors of phosphatidylinositol 3‐kinase (PI3K), on monocyte chemoattractant protein‐1 (MCP‐1) expression by human umbilical vein endothelial cells were investigated. Complete inhibition of interleukin (IL)‐1β‐induced Akt phosphorylation occurred at 50 μM LY29 or 100 nM WM. At these concentrations, LY29, but not WM, significantly inhibited constitutive and IL‐1β‐induced MCP‐1 expression at both protein and mRNA levels. LY303511 (LY30), an inactive analogue of LY29, also inhibited MCP‐1 expression. LY29 and LY30 inhibited activation of nuclear factor‐κB (NF‐κB). These results suggest that LY29 inhibits MCP‐1 expression at least in part via suppression of NF‐κB, independent of PI3K, and the structure of LY29 and LY30 may be a novel template for development of new anti‐inflammatory drugs.

Potentiation of bacterial killing activity of zinc chloride by pyrrolidine dithiocarbamate.

Zinc has antimicrobial activity and zinc salts including zinc chloride (ZnCl2) have been used for the control of oral malodor. In this study, we hypothesized that pyrrolidine dithiocarbamate (PDTC), a zinc ionophore, may enhance antimicrobial efficacy of ZnCl2. The bactericidal effectiveness of ZnCl2 alone (0.5–8 mM) or in combination with PDTC (1 or 10 μM) was evaluated by in vitro short (1 h) time-killing assays against Fusobacterium nucleatum and Porphyromonas gingivalis. Only a slight viability decrease was observed with ZnCl2 or PDTC alone after 1-h incubation. By contrast, combination of ZnCl2 and PDTC could achieve a more than 100-fold viability reduction compared with ZnCl2 or PDTC alone in F. nucleatum and P. gingivalis. Therefore, PDTC greatly enhanced the bactericidal activity of ZnCl2 against the oral malodor-producing bacteria. These results suggest that use of PDTC may be useful for enhancing bactericidal activity of antimalodor regimens of zinc salts.

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.

Development of Novel Photosensitizer Using the Buddleja officinalis Extract for Head and Neck Cancer

Photodynamic therapy (PDT) is generally safer and less invasive than conventional strategies for head and neck cancer treatment. However, currently available photosensitizers have low selectivity for tumor cells, and the burden and side effects are so great that research is needed to develop safe photosensitizers. In this study, it was confirmed that the Buddleja officinalis (BO) extract, used in the treatment of inflammation and vascular diseases, shows fluorescence when activated by LED light, and, based on this, we aimed to develop a new photosensitive agent suitable for PDT. MTT, Diff-Quick® staining, and DCF-DA were performed to measure the effects of treating head and neck cancer cells with BO extract and 625 nm LED light (BO-PDT). Cell cycle, TUNEL, and western blot assays, as well as acridine orange staining, were performed to explore the mechanism of BO-PDT-induced cell death. We found that when the BO extract was irradiated with 625 nm LED light, it showed sufficient fluorescence and stronger intracellular toxicity and ROS effect than the currently commercially available hematoporphyrin. BO-PDT resulted in a decrease of mTOR activity that was correlated with an increase in the levels of ATG5, beclin-1, and LC3-II, which interfere with the formation of autophagosomes. In addition, BO-PDT induced the activation of PARP and led to an increase in the expression of proapoptotic protein Bax and a decrease in the expression of the antiapoptotic protein Bcl-2. Moreover, BO-PDT has been shown to induce the autophagy pathway 4 h after treatment, while apoptosis was induced 16 h after treatment. Finally, we confirmed that BO-PDT caused cell death of head and neck cancer cells via the intrinsic pathway. Therefore, we suggest that BO extract can be used as a new photosensitizer in PDT of head and neck cancer.

Characterization of a submandibular gland sialolith: micromorphology, crystalline structure, and chemical compositions

OBJECTIVE The aim of this study was to understand the mechanism of mineralization and growth of a sialolith by analyzing its micromorphology, crystalline structure, and chemical compositions. STUDY DESIGN A sialolith was removed along with submandibular salivary gland from a patient. After cross-cutting and polishing the sialolith, its morphology, chemical compositions, crystalline structure, and chemical states were analyzed by using optical camera, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractometer, Fourier transform infrared spectrophotometer, and transmittance electron microscopy. RESULTS The sialolith had a core composed of organic material, such as lipid compounds, and the surrounding mineralized shell structure mostly consisted of hydroxyapatite. In the transition zone between the organic core and mineralized shell layers, inorganic layers were arranged alternately with organic layers. Congregated globular structures were calcified with hydroxyapatite and whitlockite crystallites. Analysis of crystalline structures and chemical compositions suggested that calcium phosphate minerals containing magnesium, such as whitlockite, were developed in the initial stage and gradually transformed into crystallites composed of hydroxyapatite during the growth of crystallites. CONCLUSIONS Sialolith with an organic core grew as inorganic materials were deposited and calcified in alternate layers. The mineralization process might include the initial whitlockite development and successive transformation into more stable hydroxyapatite.

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.