• Imaging Science in Dentistry
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• v.51 no.4
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• pp.383-388
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• 2021

Purpose: The aim of this study was to evaluate the root canal morphology of mesial roots of mandibular first molars. Materials and Methods: Forty extracted mandibular first molars were used in this study. The morphological examination of root canals was conducted in accordance with the Vertucci classification using micro-computed tomography (micro-CT). Any aberrant root canal configurations not included in the Vertucci classification were recorded, and their frequency was established using descriptive statistics. Intra-observer reliability was assessed using the Wilcoxon signed-rank test, while inter-observer reliability was assessed using the Cohen kappa test. Significance was evaluated at the P<0.05 level. Results: The mesial roots of mandibular first molars had canal configurations of type I (15%), type II (7.5%), type III (25%), type IV (10%), type V (2.5%), type VI (7.5%), and type VII (7.5%). The images showed 10 (25%) additional configuration types that were not included in the Vertucci classification. These types were 1-3-2-3, 1-2-3-2-3, 2-3-1, 2-3, 1-2-3-1, 2-1-2-3, 3-2-1, 1-2-3-1, 2-3-2-3, and 1-2-1-2-1. The intra-observer differences were not statistically significant(P>0.05) and the kappa value for inter-observer agreement was found to be 0.957. Conclusion: Frequent variations were detected in mesial roots of mandibular first molars. Clinicians should take into consideration the complex structure of the root canal morphology before commencing root canal treatment procedures to prevent iatrogenic complications. Micro-CT was a highly suitable method to provide accurate 3-dimensional visualizations of root canal morphology.

• Molecules and Cells
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• v.45 no.8
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• pp.575-587
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• 2022

Human ABCB6 is an ATP-binding cassette transporter that regulates heme biosynthesis by translocating various porphyrins from the cytoplasm into the mitochondria. Here we report the cryo-electron microscopy (cryo-EM) structures of human ABCB6 with its substrates, coproporphyrin III (CPIII) and hemin, at 3.5 and 3.7 Å resolution, respectively. Metal-free porphyrin CPIII binds to ABCB6 within the central cavity, where its propionic acids form hydrogen bonds with the highly conserved Y550. The resulting structure has an overall fold similar to the inward-facing apo structure, but the two nucleotide-binding domains (NBDs) are slightly closer to each other. In contrast, when ABCB6 binds a metal-centered porphyrin hemin in complex with two glutathione molecules (1 hemin: 2 glutathione), the two NBDs end up much closer together, aligning them to bind and hydrolyze ATP more efficiently. In our structures, a glycine-rich and highly flexible "bulge" loop on TM helix 7 undergoes significant conformational changes associated with substrate binding. Our findings suggest that ABCB6 utilizes at least two distinct mechanisms to fine-tune substrate specificity and transport efficiency.

• Genomics & Informatics
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• v.21 no.2
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• pp.17.1-17.12
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• 2023

Coronavirus has left severe health impacts on the human population, globally. Still a significant number of cases are reported daily as no specific medications are available for its effective treatment. The presence of the CD147 receptor (human basigin) on the host cell facilitates the severe acute respiratory disease coronavirus 2 (SARS-CoV-2) infection. Therefore, the drugs that efficiently alter the formation of CD147 and spike protein complex could be the right drug candidate to inhibit the replication of SARS-CoV-2. Hence, an e-Pharmacophore model was developed based on the receptor-ligand cavity of CD147 protein which was further mapped against pre-existing drugs of coronavirus disease treatment. A total of seven drugs were found to be suited as pharmacophores out of 11 drugs screened which was further docked with CD147 protein using CDOCKER of Biovia discovery studio. The active site sphere of the prepared protein was 101.44, 87.84, and 97.17 along with the radius being 15.33 and the root-mean-square deviation value obtained was 0.73 Å. The protein minimization energy was calculated to be -30,328.81547 kcal/mol. The docking results showed ritonavir as the best fit as it demonstrated a higher CDOCKER energy (-57.30) with correspond to CDOCKER interaction energy (-53.38). However, authors further suggest in vitro studies to understand the potential activity of the ritonavir.

• Journal of Photoscience
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• v.11 no.32
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• pp.71-74
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• 2004

The macrocycle L exhibited a switch on-off behavior through the fluorescent responses by aromatic imine molecule 1 (X=H) / trifluoroacetic acid (TFA). In the 'switch on' state, it was supposed that the aromatic imine molecule 1 is in the cavity of macrocycle L and a photoinduced electron transfer (PET) from the nitrogen of azacrown part to the anthryl group is inhibited by the interaction between the aromatic imine molecule 1 and the azacrown part of macrocycle L. In the 'switch off' state, it was supposed that the protonated imine molecule 1 is induced by the continuous addition of TFA and a repulsion between the protonated azacrown part and the protonated imine molecule 1 is occurred. It was considered that this process induces the intermolecular PET from the protonated imine molecule 1 to the anthryl group of macrocycle L because of a proximity effect between the anthryl group and the protonated imine molecule 1. From the investigation of the transient emission decay curve, the macrocycle L showed three components (3.45 ns (79.72%), 0.61 ns (14.53%), and 0.10 ns (5.75%). When the imine molecule 1 was added in the macrocycle L as molar ratio=1:1, the first main component showed a little longer lifetime as 3.68 ns (82.75%) although the other two components were similar as 0.64 ns (14.28%) and 0.08 ns (2.96%). On the contrary, when the imine molecule 3 (X=C1) was added in the macrocycle L as molar ratio=l:1, all the three components were decreased such as 3.27 ns (69.83%), 0.44 ns (13.24%), and 0.06 ns (16.93%). The fluorescent pH titration of macrocycle L was carried out from pH=3 to pH=9. The macrocycle L and C $U^{2+}$- macrocycle L complex were intersected at about pH=5, while the E $u^{3+}$ -macrocycle L complex was intersected at about pH=5.5. In addtion, we investigated the fluorescence change of macrocycle L as a function of the substituent constant ($\sigma$$_{p}$$^{o}$) showing in the para-substituent with electron withdrawing groups (X=F, Cl) and electron donating groups (X=C $H_3$, OC $H_3$, N(C $H_3$)$_2$), respectively, as well as non-substituent (X=H).).ctively, as well as non-substituent (X=H).

• Journal of Yeungnam Medical Science
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• v.32 no.2
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• pp.71-79
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• 2015

Background: Recent studies have shown that the nontuberculosis mycobacterium (NTM) recovery rate in clinical cultures has increased within Korea. However, another study conducted by a secondary hospital within Daegu reported different results. Therefore, the purpose of this study is to understand and evaluate the microbiological distribution and clinical features of NTM in Daegu. Methods: A retrospective study was conducted on 11,672 respiratory specimens undergoing acid fast bacilli (AFB) culture from 6,685 subjects who visited Yeungnam University Respiratory Center from January 2012 to December 2013. Results: Of the 11,672 specimens undergoing AFB culture, 1,310 specimens (11.2%) showed positive results. Of these specimens, NTM was recovered from 587 specimens, showing a recovery rate of 44.8%. Identification test for NTM was performed on 191 subjects; the results were as follows: M. avium-intracellulare complex (MAC) 123 (64.4%), M. abscessus 20 (10.5%), M. kansasii 12 (6.3%), and 33 other NTM germ strains. Of the 382 subjects with NTM, 167 were diagnosed with pulmonary NTM disease (43.7%), however virulence differed depending on NTM strain. Multivariate analysis showed that nodular bronchiectasis, the nodules, and finding consistent with cavity under imaging study were statistically significant for triggering pulmonary NTM disease. AFB culture showing MAC and M. abscessus was statistically significant as well. Positive predictive value for NTM polymerase chain reaction (NTM-PCR) was 88.6%. Conclusion: Results for NTM recovery rate within the Daegu area were similar to those for the Seoul metropolitan area. We can assume that NTM infection is increasing in our community, therefore AFB-positive subjects (1) should undergo NTM-PCR, (2) should have their culture results checked for differentiation of mycobacterium tuberculosis complex (MTB) from NTM, and (3) undergo NTM identification test to confirm its type. Administration of treatment with the above results should be helpful in improving the patients' prognosis.

• Korean Journal of Crystallography
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• v.2 no.1
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• pp.17-22
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• 1991

The crystal structure of an acetylene sorption complex of vacuum dehydrated fully Cda+ _exchanged zeolite A has been determined from three-dimensional X-ray diffraction data gathered by counter method. The structure was solved and refined in the cubic space group Pm3m at 294(1) K, a=12.202(3) A and Z=1. We crystal was prepared by dehydration at 723 K and 2.67×104 Pa for 2 days, followed by exposure to 1.60×104 Pa of acetylene gas at 298(1) K. All six Cd2+ions per unit cell are associated with 6-oxgen rings of the aluminosilicate framework. They are distributed over two distinguished threefold axes of unit cell; two of these Cd2+ ions are recessed 0.694 into the sodalite unit from (111) plane of three 0(3)'s and each approaches three framework oxides; the other four Cd2+ ions extend approximately 0.586A into the large cavity. The four Cd2+ ions are in a near tetrahedral environment, 2.220(9)A from·three framework oxide ions and 2.74(7) A from each carbon atom of an acetylene molecule(which is here counted as a monodentate ligand). Full matrix least squares refinement converged to the final error indices R1=0.093 and R2=0.105 using the 292 independent reflections for which I>3σ(I).

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.143-158
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• 1990

Metal complexes were prepared by reacting uranium (Ⅵ), thorium (Ⅳ) and rare earth metal (Ⅲ) ions including Nd (Ⅲ), Sm (Ⅲ) and Ho (Ⅲ) with macrocyclic ligands including five crown ethers, nine crownands and one cryptand ligands, and subjected to NMR studies in order to examine coordination sites of the ligands and compositions of the complexes formed. Among the marcocyclic ligands, crown ethers and crownand ligands have shown down-field shifts of the methylene protons of the lcigands by forming stable complexes with all the metal ions and the differences of chemical shifts were decreased as increasing of the cavity-size of crown ethers for the same metal ions and decreasing of the atomic number of the rare earth metals for the same ligands. It has been found that crownand 22 gave a stable complex with uranium(Ⅵ) ion by the coordination through both oxygen and nitrogen atoms of the ligand whereas no complex was formed with the rare earth metal(Ⅲ) ions, which on the other hand were found to form stable complexes with cryptand 221. The rest of the crowand ligands have also been found to form stable complexes with uranium(Ⅵ) ion by coordinating through all the oxygen and nitrogen atoms of the ligands whereas no complexes were formed with the rare earth metal(Ⅲ) ions. It has also been shown by 1H-NMR study that uranium(Ⅵ), thorium(Ⅳ) and rare earth metal(Ⅲ) ions formed 1:1 complexes with the macrocyclic ligands except for thorium(Ⅳ) complex of 12C4 in which the mole ratio of metal to ligand is 1:2. More stable metal complexes show larger changes in chemical shifts of the coordinated ligand protons. Finally, the rare earth metal(Ⅲ) complexes of 18C6 have shown ligand exchange reaction with the solvent molecules in acetylacetone solution, which was not observed for the uranium (Ⅵ) complexes.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.9-22
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• 1992

Two crystal structures of bromine sorption complexes of vacuum dehydrated Cd(ll)-exchanged zeolite A have been determined by single-crystal xray diffraction techniques in the cubic space group Pm3m at 21(1) ℃. Both crystals were ion exchanged in flowing streams of exchange solution In which mole ratio of Cd(NO3)2 and Cd(OOCCH3)B was 1:1 with a total concentration of 0.05 M. First crystal was dehydrated at 450℃ and 2 ×10-6 Torr for two days. Second crystal was dehydrated at 650℃ and 2 ×10-6 Torr for two days. Both crystals were then treated with 160 Torr for two days. Second crystal was dehydrated at 650℃ and 2 × 10-6 Torr for two days. Both crystals were then treated with 160 Torr of zeolitically dried bromine vapor at 24℃. Full-matrix least-squares refinements of toe first crystal(a: 12.250(1) A )· and the second crystal(a: 12.204(2) A ) have contecoed to final error indices, Rl:0.075 and Ra:0.079 with 212 reflections, and Rl : 0.089 and Ra = 0.078 with 128 reflections, respectively, for which I >3σ(I). Crystallographic analyses of both crystals show that six Cd2+ ions are located on two different threefold axes of unit cell associated with 6-ring oxygens. Each 4.5 Cd2+ ion is recessed ca.0. 441 A Into the large cavity to complex either with Brsor with Br3from the (111) plane of 0(3), whereas each 1.5 Cd2+ ions recessed ca. 0.678 A into we sodalite unit. Approximately 1.5 Br5-and 1.5 Br3-ions are sorbed per unit cell. Each Brsion interacts and stabilized by complexing with two Cd2+ ions and framework oxide ions, while each Br3ion interacts with one Cd2+ ion and framework oxide ions. Because of residual water molecules the following reactions may be occurred inside of zeolite cavity:

• Journal of dental hygiene science
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• v.14 no.4
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• pp.477-487
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• 2014

Of the many pathogenic Candida species, Candida albicans is the main fungal pathogen of humans. The oral environmental factors considered in the Candida albicans colony forming unit test contain both host and microbial factors associated with candidiasis. In particular, Candida biofilms can develop on surfaces of prosthesis. The purpose of this study was to investigate the distribution of oral Candida species between the type of prosthesis and the situation of oral environment in patient with prosthetic appliance. The patients were 30 elderly subjects with different types of prosthesis, 7 who wore denture, 12 who wore implant and 15 who wore removable orthodontic appliance. We used Candida albicans colony forming unit test using saliva to exam the distribution of Candida albicans related with 5 oral environmental factors, gender, smoking or nonsmoking, alcohol/nonalcohol consumption, the type of prosthetic appliance and its treatment duration as well as tooth brushing frequency per day. In conclusion, for the patient's gender, site in the oral cavity and the type of prosthetic appliance and its treatment duration was associated with an increase in the distribution of Candida albicans in saliva. The distribution of Candida albicans within the oral cavity performs to be modulated to varying extents by oral environmental factors and, further investigations are required to elucidate these complex interactions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.2
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• pp.133-138
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• 1998

Choanal atresia may be membrane or bony, unilateral or bilateral. Approximately 90% of the choanal atresia are bony type. Unilateral choanal atresia often eludes the diagnosis because of the absence of subjective symptoms in the neonatal period. However, bilateral choanal atresia presents at birth with cyclic respiratory distress aggravated by feedings. So complete bilateral choanal atresia is considered as a neonatal emergency. Examinations for the diagnosis of chonal atresia include 1) attempt at passing a rubber catheter or probe through the patient s nose, 2) mirror examination of the nasopharynx, 3) digital examination of the nasopharynx, 4) X-ray examination after installation of radiopaque materal into the nasal cavity. But, computed tomography has become accepted method for evaluation of choanal atresia. Surgical repair of choanal atresia is accomplished via transnasal or transpalatal approach. Advantages of the transpalatal approach are improved exposure and the preservation of mucosal flap along the newly formed apertures. On the other hand, the transpalatal approach carries the risk of injury to the greater palatine neurovascular complex, and requires longer operative time. After careful physical and radiographic examinations, we accomplished the surgical repair of the complete bony bilateral choanal atresia via transpalatal approach without complications.