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Quantitative measurement of peri-implant bone defects using optical coherence tomography
Sulhee Kim,Se-Ryong Kang,Hee-Jung Park,Bome Kim,Tae-Il Kim,Won-Jin Yi 대한치주과학회 2018 Journal of Periodontal & Implant Science Vol.48 No.2
Purpose: The purpose of this study was to visualize and identify peri-implant bone defects in optical coherence tomography (OCT) images and to obtain quantitative measurements of the defect depth. Methods: Dehiscence defects were intentionally formed in porcine mandibles and implants were simultaneously placed without flap elevation. Only the threads of the fixture could be seen at the bone defect site in the OCT images, so the depth of the peri-implant bone defect could be measured through the length of the visible threads. To analyze the reliability of the OCT measurements, the flaps were elevated and the depth of the dehiscence defects was measured with a digital caliper. Results: The average defect depth measured by a digital caliper was 4.88±1.28 mm, and the corresponding OCT measurement was 5.11±1.33 mm. Very thin bone areas that were sufficiently transparent in the coronal portion were penetrated by the optical beam in OCT imaging and regarded as bone loss. The intraclass correlation coefficient between the 2 methods was high, with a 95% confidence interval (CI) close to 1. In the Bland-Altman analysis, most measured values were within the threshold of the 95% CI, suggesting close agreement of the OCT measurements with the caliper measurements. Conclusions: OCT images can be used to visualize the peri-implant bone level and to identify bone defects. The potential of quantitative non-invasive measurements of the amount of bone loss was also confirmed.
Structural insights into the dimer-tetramer transition of FabI from <i>Bacillus anthracis</i>
Kim, Hyun Tae,Kim, Sulhee,Na, Byeong Kwan,Chung, Jiwoung,Hwang, Eunha,Hwang, Kwang Yeon Elsevier 2017 Biochemical and biophysical research communication Vol.493 No.1
<P><B>Abstract</B></P> <P>Enoyl-ACP reductase (ENR, also known as FabI) has received considerable interest as an anti-bacterial target due to its essentiality in fatty acid synthesis. All the FabI structures reported to date, regardless of the organism, are composed of homo-tetramers, except for two structures: <I>Bacillus cereus</I> and <I>Staphylococcus aureus</I> FabI (<I>bc</I>FabI and <I>sa</I>FabI, respectively), which have been reported as dimers. However, the reason for the existence of the dimeric form in these organisms and the biological meaning of dimeric and tetrameric forms of FabI are ambiguous. Herein, we report the high-resolution crystal structure of a dimeric form of <I>Bacillus anthracis</I> FabI (<I>ba</I>FabI) and the crystal structures of tetrameric forms of <I>ba</I>FabI in the apo state and in complex with NAD<SUP>+</SUP> and with NAD<SUP>+</SUP>-triclosan, at 1.7 Å, 1.85 Å, 1.96 Å, and 1.95 Å, respectively. Interestingly, we found that <I>ba</I>FabI with a His<SUB>6</SUB>-tag at its C-terminus exists as a dimer, whereas untagged-<I>ba</I>FabI exists as a tetramer. The His<SUB>6</SUB>-tag may block the dimer-tetramer transition, since <I>ba</I>FabI has relatively short-length amino acids (<SUP>255</SUP>LG<SUP>256</SUP>) after the 3<SUB>10</SUB>-helix η7 compared to those of FabI of other organisms. The dimeric form of <I>ba</I>FabI is catalytically inactive, because the α-helix α5 occupies the NADH-binding site. During the process of dimer-tetramer transition, this α5 helix rotates about 55° toward the tetramer interface and the active site is established. Therefore, tetramerization of <I>ba</I>FabI is required for cofactor binding and catalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Bacillus anthracis</I> FabI (<I>ba</I>FabI) dimer high-resolution crystal structure was reported. </LI> <LI> We obtained snapshots of <I>ba</I>FabI tetramer states (apo, NAD<SUP>+</SUP>-; NAD<SUP>+</SUP>-triclosan-bound). </LI> <LI> The C-terminal His<SUB>6</SUB>-tag may block the dimer-tetramer transition. </LI> <LI> Dimeric <I>ba</I>FabI is catalytically inactive as α-helix α5 occupies NADH-binding site. </LI> <LI> Tetramerization of <I>ba</I>FabI is required for cofactor binding and catalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Structural Basis for Inhibitor-Induced Hydrogen Peroxide Production by Kynurenine 3-Monooxygenase
Kim, Hyun Tae,Na, Byeong Kwan,Chung, Jiwoung,Kim, Sulhee,Kwon, Sool Ki,Cha, Hyunju,Son, Jonghyeon,Cho, Joong Myung,Hwang, Kwang Yeon Elsevier 2018 Cell chemical biology Vol.25 No.4
<P><B>Summary</B></P> <P>Kynurenine 3-monooxygenase (KMO) inhibitors have been developed for the treatment of neurodegenerative disorders. The mechanisms of flavin reduction and hydrogen peroxide production by KMO inhibitors are unknown. Herein, we report the structure of human KMO and crystal structures of <I>Saccharomyces cerevisiae</I> (<I>sc</I>) and <I>Pseudomonas fluorescens</I> (<I>pf</I>) KMO with Ro 61-8048. Proton transfer in the hydrogen bond network triggers flavin reduction in <I>p</I>-hydroxybenzoate hydroxylase, but the mechanism triggering flavin reduction in KMO is different. Conformational changes via π-π interactions between the loop above the flavin and substrate or non-substrate effectors lead to disorder of the C-terminal α helix in <I>sc</I>KMO and shifts of domain III in <I>pf</I>KMO, stimulating flavin reduction. Interestingly, Ro 61-8048 has two different binding modes. It acts as a competitive inhibitor in <I>sc</I>KMO and as a non-substrate effector in <I>pf</I>KMO. These findings provide understanding of the catalytic cycle of KMO and insight for structure-based drug design of KMO inhibitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We report the structures of human KMO and Ro 61-8048-complexed <I>sc</I>KMO and <I>pf</I>KMO </LI> <LI> We propose the triggering mechanism of flavin reduction in KMO </LI> <LI> Ro 61-8048 adopts distinct binding modes in <I>S</I>. <I>cerevisiae</I> and <I>P</I>. <I>fluorescens</I> KMOs </LI> <LI> Our findings provide insight for structure-based drug design of KMO inhibitors </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>
Quantitative measurement of peri-implant bone defects using optical coherence tomography
Kim, Sulhee,Kang, Se-Ryong,Park, Hee-Jung,Kim, Bome,Kim, Tae-Il,Yi, Won-Jin Korean Academy of Periodontology 2018 Journal of Periodontal & Implant Science Vol.48 No.2
Purpose: The purpose of this study was to visualize and identify peri-implant bone defects in optical coherence tomography (OCT) images and to obtain quantitative measurements of the defect depth. Methods: Dehiscence defects were intentionally formed in porcine mandibles and implants were simultaneously placed without flap elevation. Only the threads of the fixture could be seen at the bone defect site in the OCT images, so the depth of the peri-implant bone defect could be measured through the length of the visible threads. To analyze the reliability of the OCT measurements, the flaps were elevated and the depth of the dehiscence defects was measured with a digital caliper. Results: The average defect depth measured by a digital caliper was $4.88{\pm}1.28mm$, and the corresponding OCT measurement was $5.11{\pm}1.33mm$. Very thin bone areas that were sufficiently transparent in the coronal portion were penetrated by the optical beam in OCT imaging and regarded as bone loss. The intraclass correlation coefficient between the 2 methods was high, with a 95% confidence interval (CI) close to 1. In the Bland-Altman analysis, most measured values were within the threshold of the 95% CI, suggesting close agreement of the OCT measurements with the caliper measurements. Conclusions: OCT images can be used to visualize the peri-implant bone level and to identify bone defects. The potential of quantitative non-invasive measurements of the amount of bone loss was also confirmed.
Methods for quantitative measurement of tooth wear using the area and volume of virtual model cusps
Kim, Soo-Hyun,Park, Young-Seok,Kim, Min-Kyoung,Kim, Sulhee,Lee, Seung-Pyo Korean Academy of Periodontology 2018 Journal of Periodontal & Implant Science Vol.48 No.2
Purpose: Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methosds of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. Methods: The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. Results: The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ${\rho}$ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Conclusions: Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.
Kim, Sulhee,Chang, Hyeyoon,Hwang, Jin wook,Kim, Sungtae,Koo, Ki-Tae,Kim, Tae-Il,Seol, Yang-Jo,Lee, Yong-Moo,Ku, Young,Lee, Jong-Ho,Rhyu, In-Chul Korean Academy of Periodontology 2017 Journal of Periodontal & Implant Science Vol.47 No.6
Purpose: The purpose of this study was to investigate the feasibility of regenerative therapy with a collagenated bone graft and resorbable membrane in intrabony defects, and to evaluate the effects of the novel extracellular matrix (ECM)-based membrane clinically and radiologically. Methods: Periodontal tissue regeneration procedure was performed using an ECM-based resorbable membrane in combination with a collagenated bovine bone graft in intrabony defects around the teeth and implants. A novel extracellular matrix membrane (NEM) and a widely-used membrane (WEM) were randomly applied to the test group and the control group, respectively. Cone-beam computed tomography images were obtained on the day of surgery and 6 months after the procedure. Alginate impressions were taken and plaster models were made 1 week and 6 months postoperatively. Results: The quantity of bone tissue, the dimensional changes of the surgically treated intrabony defects, and the changes in width and height below the grafted bone substitutes showed no significant difference between the test and control groups at the 6-month examination. Conclusions: The use of NEM for periodontal regeneration with a collagenated bovine bone graft showed similar clinical and radiologic results to those obtained using WEM.