• Restorative Dentistry and Endodontics
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• v.32 no.2
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• pp.102-110
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• 2007

The purpose of this study was to obtain the basic information for the improvement of dental environment by investigating the presence of methicillin- or vancomycin-resistant Staphylococcus aureus (MRSA or VRSA) isolated from dental health care workers (DHCWs) and environment of the Chosun University Dental Hospital (CUDH) and a private dental clinic (control group). Staphylococcus aureus (S. aureus) was isolated from anterior nares of 42 DHCWS and 38 sites, unit chairss, x-ray devices, computers, etc., at 10 departments of the CUDH and 20 DHCWs and 11 sites at the private dental clinic. S. aureus was isolated on mannitol salt agar plate and confirmed by PCR with S. aureus species-specific primer. Antimicrobial susceptibility test of clinical isolates of S. aureus against several antibiotics including methicillin (oxacillin) was performed by investigating minimum inhibitory concentration (MIC) using broth microdilution assay. In addition, PCR was performed to detect the methicillin- or vancomycin-resistant gene. The data showed that one strain of S. aureus was isolated from DHCWs of the CUDH and three strains of S. aureus was isolated from 3 samples of the private dental clinic, respectively. All of the isolates from the CUDH and the private dental clinic had resistance to penicillin G, amoxicillin and vancomycin and susceptibility to oxacillin and ciprofloxacin. The S. aureus strains were already obtained the resistance to penicillin G and amoxicillin. These results suggest that two dental clinics were under relatively safe environment.

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.468-474
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• 2015

PURPOSE. The aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time. MATERIALS AND METHODS. This descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week ($t_1$) and 4 months ($t_2$) after the RPD was inserted ($t_0$). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity). RESULTS. A total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 ($t_1$) and 96 ($t_2$) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for $t_1$ and 17 for $t_2$, which were grouped in 5 phyla: Firmicutes ($t_1=82%$; $t_2=60%$), Actinobacteria ($t_1=5%$; $t_2=10%$), Bacteroidetes ($t_1=2%$; $t_2=6%$), Proteobacteria ($t_1=10%$; $t_2=15%$) and Fusobacteria ($t_1=1%$; $t_2=8%$). The libraries also include 3 novel phylotypes for $t_1$ and 11 for $t_2$. Library $t_2$ differs from $t_1$ (P=.004); $t_1$ is a subset of the $t_2$ (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in $t_2$. CONCLUSION. The biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.

• Journal of Life Science
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• v.29 no.1
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• pp.123-128
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• 2019

The use of 16S rDNA is commonplace in the determination of prokaryotic species. However, it has limitations, and there are few studies at the genus level. We investigated conserved genes and metabolic pathways at the genus level in 28 strains of 13 genera of prokaryotes using the COG database (conserved genes) and MetaCyc database (metabolic pathways). Conserved genes compared to total genes (core genome) at the genus level ranged from 27.62%(Nostoc genus) to 71.76%(Spiribacter genus), with an average of 46.72%. The lower ratio of core genome meant the higher ratio of peculiar genes of a prokaryote, namely specific biological activities or the habitat may be varied. The ratio of common metabolic pathways at the genus level was higher than the ratio of core genomes, from 58.79% (Clostridium genus) to 96.31%(Mycoplasma genus), with an average of 75.86%. When compared among other genera, members of the same genus were positioned in the closest nodes to each other. Interestingly, Bacillus and Clostridium genera were positioned in closer nodes than those of the other genera. Archaebacterial genera were grouped together in the ortholog and metabolic pathway nodes in a phylogenetic tree. The genera Granulicella, Nostoc, and Bradyrhizobium of the Acidobacteria, Cyanobacteria, and Proteobacteria phyla, respectively, were grouped in an ortholog content tree. The results of this study can be used for (i) the identification of common genes and metabolic pathways at each phylogenetic level and (ii) the improvement of strains through horizontal gene transfer or site-directed mutagenesis.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6155-6157
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• 2012

Background: Mutations in the MAPK (Mitogen Activated Protein Kinase) signaling pathway - EGFR/Ras/RAF/MEK have been associated with the development of several carcinomas. ERK2, a downstream target of the MAPK pathway and a founding member of the MAPK family is activated by cellular signals emanating at the cell membrane. Activated ERK2 translocates into the nucleus to transactivate genes that promote cell proliferation. MKP - a dual specific phosphatase - interacts with activated ERK2 via the common docking (CD) domain of the later to inactivate (dephosphorylate) and effectively terminate further cell proliferation. A constitutively active form of ERK2 carrying a single point mutation - E322K in its CD domain, was earlier reported by our laboratory. In the present study, we investigated the prevalence of this CD domain E322K mutation in 88 well differentiated OSCC tissue samples. Materials and Method: Genomic DNA specimens isolated from 88 oral squamous cell carcinoma tissue samples were amplified with primers flanking the CD domain of the ERK2 gene. Subsequently, PCR amplicons were gel purified and subjected to direct sequencing to screen for mutations. Results: Direct sequencing of eighty eight OSCC samples identified an E322K CD domain mutation in only one (1.1%) OSCC sample. Conclusions: Our result indicates that mutation in the CD domain of ERK2 is rare in OSCC patients, which suggests the role of genetic alterations in other mitogenic genes in the development of carcinoma in the rest of the patients. Nevertheless, the finding is clinically significant, as the relatively rare prevalence of the E322K mutation in OSCC suggests that ERK2, being a common end point signal in the multi-hierarchical mitogen activated signaling pathway may be explored as a viable drug target in the treatment of OSCC.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.180-186
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• 1999

Eugenol has been reported to reduce odontogenic pain and is known to have a structure similar to capsaicin, a potent stimulant of certain nociceptors. We have hypothesized that the analgesic effect of eugenol may be due, in part, to inhibition of capsaicin-sensitive nociceptors. To test this hypothesis, we evaluate whether eugenol inhibits capsaicin-sensitive release of immunoreactive calcitonin generated peptide(iCGRP) from bovine dental pulp. Freshly extracted bovine incisors were transported to the lab. on ice, Spilitted and pulp tissue was removed. The tissue was chopped into 200${\mu}m$ slices. Dental pulp was superfused(340 ${\mu}l/min$) in vitro with oxygenated Kreb's buffer. Eugenol and vehicle(0.02% 2-hydroxyl-${\beta}$-cyclodextrin) were administered prior to stimulation of pulp with capsaicin and iCGRP was measured by RIA. The results were as follows: 1. Administration of eugenol has no effect on basal release of iCGRP. 2. In the vehicle treated group, capsaicin evoked a 2.5-fold increase over basal iCGRP levels. 3. Administration of eugenol(600 ${\mu}M$) reduced capsaicin evoked release of iCGRP by more than 40%(153.4${\pm}$41.1% vs 258.9${\pm}$21.7%). 4. 2-hydroxylpropyl-${\beta}$-cyclodextrin of less than 0.02% is found to be an effective vehicle to dissolve eugenol without evoking iCGRP release from dental bovine pulp. These data indicate that eugenol inhibits pulpal capsaicin-sensitive fibers and suggest that intracanal medicament of eugenol may relieve pain, in part, by this mechanism.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1070-1083
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• 2015

A gene (GT-SM3B) encoding a thermostable secreted oligoendopeptidase (GT-SM3B) was cloned from the thermophile Geobacillus thermoleovorans DSM 15325. GT-SM3B is 1,857 bp in length and encodes a single-domain protein of 618 amino acids with a 23-residue signal peptide having a calculated mass of 67.7 kDa after signal cleavage. The deduced amino acid sequence of GT-SM3B contains a conservative zinc metallopeptidase motif (His⁴⁰⁰-Glu⁴⁰¹-X-XHis⁴⁰⁴). The described oligopeptidase belongs to the M3B subfamily of metallopeptidases and displays the highest amino acid sequence identity (40.3%) to the oligopeptidase PepF_Ba from mesophilic Bacillus amyloliquefaciens 23-7A among the characterized oligopeptidases. Secretory production of GT-SM3B was used, exploiting successful oligopeptidase signal peptide recognition by Escherichia coli BL21 (DE3). The recombinant enzyme was purified from the culture fluid. Homodimerization of GT-SM3B was determined by SDS-PAGE. Both the homodimer and monomer were catalytically active within a pH range of 5.0–8.0, at pH 7.3 and 40℃, showing the K_m, V_max, and k_cat values for carbobenzoxy-Gly-Pro-Gly-Gly-Pro-Ala-OH peptidolysis to be 2.17 ± 0.04 × 10^-6 M, 2.65 ± 0.03 × 10^-3 µM/min, and 5.99 ± 0.07 s^-1, respectively. Peptidase remained stable at a broad pH range of 5.0–8.0. GT-SM3B was thermoactive, demonstrating 84% and 64% of maximum activity at 50℃ and 60℃, respectively. The recombinant oligopeptidase is one of the most thermostable M3B peptidase, retaining 71% residual activity after incubation at 60℃ for 1 h. GT-SM3B was shown to hydrolyze a collagenous peptide mixture derived from various types of collagen, but less preferentially than synthetic hexapeptide. This study is the first report on an extracellular thermostable metallo-oligopeptidase.

• International Journal of Oral Biology
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• v.45 no.1
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• pp.25-31
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• 2020

Enamel knot (EK)-a signaling center-refers to a transient morphological structure comprising epithelial tissue. EK is believed to regulate tooth development in early organogenesis without its own cellular alterations, including proliferation and differentiation. EKs show a very simple but conserved structure and share functions with teeth of recently evolved vertebrates, suggesting conserved signaling in certain organs, such as functional teeth, through the course of evolution. In this study, we examined the expression patterns of key EK-specific genes including Dusp26, Fat4, Meis2, Sln, and Zpld1 during mice embryogenesis. Expression patterns of these genes may reveal putative differentiation mechanisms underlying tooth morphogenesis.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.20.1-20.14
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• 2020

Objectives: To minimize the tooth sensitivity caused by in-office bleaching, many dentists use non-steroidal anti-inflammatory drugs and topical desensitizing gels containing potassium nitrate and sodium fluoride. This study aimed to evaluate the influence of these substances on inflammation and the expression of substance P and calcitonin gene-related peptide in pulp nerve fibers. Materials and Methods: Seventy-two rats were divided into 6 groups as follows: GI, control; GII, only dental bleaching; GIII, only ibuprofen; GIV, ibuprofen administered 30 minutes before and after the bleaching treatment and every 12 hours until the analysis; GV, only topical application of a desensitizing agent; and GVI, topical application of a desensitizing agent before dental bleaching. Placebo gel was applied to the upper left jaw and the bleaching agent was applied to the upper right jaw in all groups. Subsequently, the groups were divided into 3 subgroups based on the time of analysis: 0, 24, and 48 hours after bleaching (n = 8). The rats were euthanized and the maxillae were processed and evaluated by histopathological and immunohistochemical analyses. The data were analyzed using the Kruskal-Wallis test, followed by the Dunn test (p < 0.05). Results: In the bleaching groups, the inflammatory process and expression of neuropeptides decreased over time. The animals in which a desensitizing agent was applied showed better results within 24 hours. Conclusions: The use of a desensitizing agent had positive effects on inflammation and pain-related neuropeptide expression, minimizing the painful effects of dental bleaching treatment.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.545-545
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• 2003

Chitosan is applied as a dressing for oral mucous wound and a tampon following radical treatment of maxillary sinus. Furthermore, it is being investigated as an absorbing membrane for endodontic and periodontic surgeries. A few studies have reported osteoconduction and osteogenesia at the site of chitosan implant in vivo. However, compared with soft tissue healing processes, the mechanisms concerning effects of chitosan for biological mineralization have not yet been resoil In the present study, we studied the gene expression pattern using cDNA microarray and RT-PCR analyses in hard tissue forming osteoblasts cultured with water-soluble and low molecular weight chitooligosaccharide. cDNA microarray analysis revealed that 16 genes were expressed at 〉1.5-fold higher signal ratio levels in the experimental group compared with the control group after 3 days. RT-PCR analysis showed that chitosan oligomer induced an increase in the expression of two genes, CD56 antigen and tissue-type plasminogen activator. Furthermore, the expression of mRNAs for BMP-2 was almost identical in the experimental and control groups after 3 days of culture, but slightly increased after 7 days of culture with chitosan oligomer. These results suggest that a super-low concentration of chitooligosaccharide could modulate the activity of osteoblastic cells through mRNA levels and that the genes concerning cell proliferation and differentiation can be controlled by water-soluble chitosan.

• BMB Reports
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• v.56 no.10
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• pp.545-550
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• 2023

Osteoporosis is a major public health concern, which requires novel therapeutic strategies to prevent or mitigate bone loss. Natural compounds have attracted attention as potential therapeutic agents due to their safety and efficacy. In this study, we investigated the regulatory activities of boeravinone B (BOB), a natural rotenoid isolated from the medicinal plant Boerhavia diffusa, on the differentiation of osteoclasts and mesenchymal stem cells (MSCs), the two main cell components responsible for bone remodeling. We found that BOB inhibited osteoclast differentiation and function, as determined by TRAP staining and pit formation assay, with no significant cytotoxicity. Furthermore, our results showing that BOB ameliorates ovariectomy-induced bone loss demonstrated that BOB is also effective in vivo. BOB exerted its inhibitory effects on osteoclastogenesis by downregulating the RANKL/RANK signaling pathways, including NF-κB, MAPK, and PI3K/Akt, resulting in the suppression of osteoclast-specific gene expression. Further experiments revealed that, at least phenomenologically, BOB promotes osteoblast differentiation of bone marrow-derived MSCs but inhibits their differentiation into adipocytes. In conclusion, our study demonstrates that BOB inhibits osteoclastogenesis and promotes osteoblastogenesis in vitro by regulating various signaling pathways. These findings suggest that BOB has potential value as a novel therapeutic agent for the prevention and treatment of osteoporosis.