Ji-Youn Kim

Bone Regeneration Using a Mixture of Silicon-Substituted Coral HA and β-TCP in a Rat Calvarial Bone Defect Model

The demand of bone graft materials has been increasing. Among various origins of bone graft materials, natural coral composed of up to 99% calcium carbonate was chosen and converted into hydroxyapatite (HA); silicon was then substituted into the HA. Then, the Si-HA was mixed with β-tricalcium phosphate (TCP) in the ratios 100:0 (S100T0), 70:30 (S70T30), 60:40 (S60T40), and 50:50 (S50T50). The materials were implanted for four and eight weeks in a rat calvarial bone defect model (8 mm). The MBCPTM (HA:β-TCP = 60:40, Biomatalante, Vigneux de Bretagne, France) was used as a control. After euthanasia, the bone tissue was analyzed by making histological slides. From the results, S60T40 showed the fastest bone regeneration in four weeks (p < 0.05). In addition, S60T40, S50T50, and MBCPTM showed significant new bone formation in eight weeks (p < 0.05). In conclusion, Si-HA/TCP showed potential as a bone graft material.

A study on the effect of self bedside exercise program on resilience and activities of daily living for patients with hemiplegia

The purpose of this study was to design a repeatable universal rehabilitation program in which patients with hemiplegia can participate voluntarily, complementing physical and occupational therapies to increase voluntary exercise practice rate. Also, this study attempted to identify the relationship between psychological resilience due to the implementation of self-bedside exercise and functional recovery of activity of daily living (ADL). 12 patients with hemiplegia voluntarily participated in 8 weeks of self-bedside exercise 5 times a day and more than 5 days a week. Their program implementation, resilience, activities of daily living (MBI), upper limb motor functions (MFT), and balance ability (BBS) were analyzed and compared before and after the program. Compared to before implementing the program, significant increases were found in resilience, MBI, BBS, and MFT in the affected side after the implementation, and the resilience scores showed statistically positive correlation in MBI and MFT. Also, the change in resilience before and after the program implementation showed a statistically positive correlation. Therefore, it can be concluded that the self-bedside exercise developed in this study had a positive effect on voluntary participation in exercise as well as resilience and ADL. However, many studies which complement the psychological aspects of hemiparetic patients with stroke are still needed.

Development and effect of a cognitive enhancement gymnastics program for elderly people with dementia

The purpose of this study was to develop a cognitive enhancement gymnastics program for the elderly with dementia and to verify its effect. The study was conducted on 27 people with dementia being treated in a dementia day care center in Incheon city. No statistically significant differences were found in the measures Mini-Mental State Examination for Dementia Screening (MMSE-DS), Short Geriatric Depression Scale (SGDS), Seoul Activities of Daily Living (S-ADL), or rock-paper-scissors. However, the MMSE-DS and rock-paper-scissors showed improvement after 12 weeks.

Combined effects of mineral trioxide aggregate and human placental extract on rat pulp tissue and growth, differentiation and angiogenesis in human dental pulp cells

Abstract Objective The aim of this study was to evaluate the combined effects of mineral trioxide aggregate (MTA) and human placental extract (HPE) on cell growth, differentiation and in vitro angiogenesis of human dental pulp cells (HDPCs) and to identify underlying signal transduction mechanisms. In vivo dental pulp responses in rats for a pulp-capping agent were examined. Materials and methods MTS assay. ALP activity test, alizarin red S staining and RT-PCR for marker genes were carried out to evaluate cell growth and differentiation. HUVEC migration, mRNA expression and capillary tube formation were measured to evaluate angiogenesis. Signal transduction was analysed using Western blotting and confocal microscopy. The pulps of rat maxillary first molars were exposed and capped with either MTA or MTA plus HPE. Histologic observation and scoring were performed. Results Compared to treatment of HDPCs with either HPE or MTA alone, the combination of HPE and MTA increased cell growth, ALP activity, mineralized nodules and expression of marker mRNAs. Combination HPE and MTA increased migration, capillary tube formation and angiogenic gene expression compared with MTA alone. Activation of Akt, mammalian target of rapamycin (mTOR), p38, JNK and ERK MAPK, Akt, and NF-κB were significantly increased by combining HPE and MTA compared with MTA alone. Pulp capping with MTA plus HPE in rats showed superior dentin bridge formation, odontoblastic layers and dentinal tubules and lower inflammatory cell response, compared to the MTA alone group. Conclusions This study demonstrates for the first time that the use of MTA with HPE promotes cell growth, differentiation and angiogenesis in HDPCs, which were associated with mTOR, MAPK and NF-κB pathways. Direct pulp capping with HPE plus MTA showed superior results when compared with MTA alone. Thus, the combination of MTA and HPE may be useful for regenerative endodontics.

Immunolocalization patterns of cytokeratins during salivary acinar cell development in mice

Embryonic development of the mouse salivary glands begins with epithelial thickening and continues with sequential changes from the pre-bud to terminal bud stages. After birth, morphogenesis proceeds, and the glands develop into a highly branched epithelial structure that terminates with saliva-producing acinar cells at the adult stage. Acinar cells derived from the epithelium are differentiated into serous, mucous, and seromucous types. During differentiation, cytokeratins, intermediate filaments found in most epithelial cells, play vital roles. Although the localization patterns and developmental roles of cytokeratins in different epithelial organs, including the mammary glands, circumvallate papilla, and sweat glands, have been well studied, their stage-specific localization and morphogenetic roles during salivary gland development have yet to be elucidated. Therefore, the aim of this study was to determine the stage and acinar cell type-specific localization pattern of cytokeratins 4, 5, 7, 8, 13, 14, 18, and 19 in the major salivary glands (submandibular, sublingual, and parotid glands) of the mouse at the E15.5, PN0, PN10, and adult stages. In addition, cell physiology, including cell proliferation, was examined during development via immunostaining for Ki67 to understand the cellular mechanisms that govern acinar cell differentiation during salivary gland morphogenesis. The distinct localization patterns of cytokeratins in conjunction with cell physiology will reveal the roles of epithelial cells in salivary gland formation during the differentiation of serous, mucous or seromucous salivary glands.

Involvement of PI3K and PKA pathways in mouse tongue epithelial differentiation.

In mice, tongue epithelial differentiation is mainly regulated by the interactions among various signalling molecules including Fgf signalling pathways. However, the subsequent signalling modulations for epithelial maturation, initiated by Fgf signalling, remain to be elucidated. Therefore, we employed an in vitro tongue organ cultivation system along with the applications of various pharmacological inhibitors against the intracellular signalling molecules of Fgf signalling pathways, including H89, LY294002, PD98059, and U0126. Following treatments with LY294002 and H89, inhibitors for PI3K and PKA, respectively, the decreased thickness of the tongue epithelium was observed along with the alteration in cell proliferative and apoptotic patterns. Meanwhile, cultivated tongues treated with MEK inhibitor U0126 or PD98059 showed significantly decreased cell proliferation in the tongue epithelium and the mesenchyme. Based on these results, we suggest that the tongue epithelium is differentiated into multiple epithelial cell layers via the PI3K and PKA pathways in tissue-specific manner during the epithelial-mesenchymal interactions.

Development and validation of exercise rehabilitation program for cognitive function and activity of daily living improvement in mild dementia elderly

We investigated the effect of exercise rehabilitation based on fine motor movement for the elderly with mild dementia. Using electroencephalogram (EEG), the change of brain wave of them based on fine motor movement and comparing the improvement level of cognitive ability and performance capability in daily living activity was recorded. The subjects were the elderly with mild dementia living in a sanatorium in Incheon city. Mini-Mental Status Examination, activity of daily living (ADL), and the influence on depression were examined. After 8-week exercise program, significant difference in cognitive function and ADL was observed, however, and there was no significant difference in depression. In the EEG, there was a significant difference in α-wave. This study suggests the chance to remind the necessity of exercise programs for improving cognitive function and ADL of the elderly with dementia.

Analysis of the relationship between physical activity and metabolic syndrome risk factors in adults with intellectual disabilities

The purpose of this study was to investigate the relationship between physical activities and metabolic syndrome risk factors in adults with intellectual disabilities. Seventeen adults with intellectual disabilities at a sheltered workshop wore Actical for 5 days on workdays to measure their physical activity, and blood samples were taken to measure their physical fitness factors and examine their risk factors for metabolic syndrome. The average daily physical activity was found to be 655.41± 129.36 kcal, and the average total physical activity over 5 days was 3,224.94±149.68 kcal. A positive correlation was confirmed between physical activity and muscular strength, muscular endurance, total cholesterol, low-density lipoprotein cholesterol and disability rating. Factors that predicted physical activity of adults with disabilities were disability rating (t=6.280, P<0.001) and glycated hemoglobin (t= −2.315, P<0.036), which had a 73.9% correlation (R2=0.739) with the physical activities of adults with intellectual disabilities. In conclusion, the physical activity level of adults with intellectual disabilities was significantly lower than that of adults in similar age groups, and such low physical activity may affect their muscular strength, muscular endurance, and metabolic syndrome risk factors. Therefore, additional studies on programs to improve and enhance physical activities at sheltered workshops, where adults with intellectual disabilities are mainly supervised and active, and guidelines for continuous health management are needed.

Gene profiling involved in fate determination of salivary gland type in mouse embryogenesis

Salivary gland (SG) development involves dynamic epithelial-mesenchymal interactions resulting in the formation of highly branched epithelial structures that produce and secrete saliva. The SG epithelium differentiates into saliva-producing terminal buds, i.e., acini, and transporting ducts. Most studies on the salivary gland have focused on branching morphogenesis; however, acinar cell differentiation underlying the determination of serous or mucous salivary glands is unclear. The objective of this study was to identify the mesenchymal signaling molecules involved in the epithelial differentiation of the salivary gland type as serous or mucous. Salivary glands undergoing stage-specific development, including the parotid gland (PG) and the sublingual gland (SLG) at embryonic day 14.5 (E14.5) were dissected. The glands were treated with dispase II to separate the epithelium and the mesenchyme. RNA from mesenchyme was processed for microarray analysis. Thereafter, microarray data were analyzed to identify putative candidate molecules involved in salivary gland differentiation and confirmed via quantitative reverse transcription polymerase chain reaction. The microarray analysis revealed the expression of 31,873 genes in the PG and SLG mesenchyme. Of the expressed genes 21,026 genes were found to be equally expressed (Fold change 1.000) in both PG and SLG mesenchyme. The numbers of genes expressed over onefold in the PG and SLG mesenchyme were found to be 5247 and 5600 respectively. On limiting the fold-change cut off value over 1.5 folds, only 214 and 137 genes were expressed over 1.5 folds in the PG and the SLG mesenchyme respectively. Our findings suggest that differential expression patterns of the mesenchymal signaling molecules are involved in fate determination of the salivary acinar cell types during mouse embryogenesis. In the near future, functional evaluation of the candidate genes will be performed using gain- and loss-of-function mutation studies during in vitro organ cultivation.

A novel organosulfur compound, thiacremonone, regulates RANKL-induced osteoclast differentiation

The medicinal properties of functionally active organosulfur compounds have received great attention for applications in treating various diseases. Thiacremonone (2,4-dihydroxy-2,5-dimethyl-thiophene-3-one, THIA) is a novel organosulfur compound generated from high-temperature-high-pressure-treated garlic and has been reported to display pharmacological effects against various diseases. However, the role of THIA in bone resorbing cells was not reported. Herein, we have examined the pharmacological properties of THIA on osteoclast differentiation in primary cultured bone marrow macrophages (BMMs). Our results showed that THIA suppressed receptor activator of NF-κB ligand (RANKL)-induced gene expression (c-Fos and NF-ATc1) for osteoclast differentiation under no cytotoxicity condition. In addition, THIA significantly inhibited TRAP positive multinucleated osteoclasts and F-actin ring formation during RANKL-mediated osteoclastogenesis. However, in primary cultured calvarial pre-osteoblasts, THIA did not influence the cytotoxicity and osteoblast differentiation, as assessed from the alkaline phosphatase (ALP) activity and mineralized nodule formation. Our findings have suggested that THIA can be considered as a potential agent for the therapeutics of bone diseases such as osteoporosis, alveolar bone resorption, and osteoarthritis.