• Biomedical Science Letters
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• v.21 no.1
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• pp.40-49
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• 2015

Mesenchymal stem cells (MSCs) have the ability to self-renew and differentiate into multi-lineage cells, thus highlighting the feasibility of using umbilical cord blood-derived MSCs (UCB-MSCs) for cell-therapy and tissueengineering. However, the low numbers of UCB-MSC derived from clinical samples requires that an ex vivo expansion step be implemented. As most stem cells reside in low oxygen tension environments (i.e., hypoxia), we cultured the UCBMSCs under 3% $O_2$ or 21% $O_2$ and the following parameters were examined: proliferation, senescence, differentiation and stem cell specific gene expression. UCB-MSCs cultured under hypoxic conditions expanded to significantly higher levels and showed less senescence compared to UCB-MSCs cultured under normoxic conditions. In regards to differentiation potential, UCB-MSCs cultured under hypoxic and normoxic conditions both underwent similar levels of osteogenesis as determined by ALP and von Kossa assay. Furthermore, UCB-MSCs cultured under hypoxic conditions exhibited higher expression of OCT4, NANOG and SOX2 genes. Moreover, cells expanded under hypoxia maintained a stem cell immnunophenotype as determined by flow cytometry. These results demonstrate that the expansion of human UCB-MSCs under a low oxygen tension microenvironment significantly improved cell proliferation and differentiation. These results demonstrate that hypoxic culture can be rapidly and easily implemented into the clinical-scale expansion process in order to maximize UCB-MSCs yield for application in clinical settings and at the same time reduce culture time while maintaining cell product quality.

• Childhood Kidney Diseases
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• v.12 no.1
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• pp.11-22
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• 2008

Telomeres consist of tandem guanine-thymine(G-T) repeats in most eukaryotic chromosomes. Human telomeres are predominantly linear, double stranded DNA as they ended in 30-200 nucleotides(bases,b) 3'-overhangs. In DNA replication, removal of the terminal RNA primer from the lagging strand results in a 3'-overhang of uncopied DNA. This is because of bidirectional DNA replication and specificity of unidirectional DNA polymerase. After the replication, parental and daughter DNA strands have unequal lengths due to a combination of the end-replication problem and end-processing events. The gradual chromosome shortening is observed in most somatic cells and eventually leads to cellular senescence. Telomere shortening could be a molecular clock that signals the replicative senescence. The shortening of telomeric ends of human chromosomes, leading to sudden growth arrest, triggers DNA instability as biological switches. In addition, telomere dysfunction may cause chronic allograft nephropathy or kidney cancers. The renal cell carcinoma(RCC) in women may be less aggressive and have less genomic instability than in man. Younger patients with telomere dysfunction are at a higher risk for RCC than older patients. Thus, telomeres maintain the integrity of the genome and are involved in cellular aging and cancer. By studying the telomeric DNA, we may characterize the genetic determinants in diseases and discover the tools in molecular medicine.

• Molecular Medicine Reports
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• v.20 no.5
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• pp.4111-4118
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• 2019

The administration of D-galactose triggers brain aging by poorly understood mechanisms. It is generally recognized that D-galactose induces oxidative stress or affects protein modifications via receptors for advanced glycated end products in a variety of species. In the present study, we aimed to investigate the involvement of astrocytes in D-galactose-induced brain aging in vitro. We found that D-galactose treatment significantly suppressed cell viability and induced cellular senescence. In addition, as of the accumulation of senescent cells, we proposed that the senescence-associated secretory phenotype (SASP) can stimulate age-related pathologies and chemoresistance in brain. Consistently, senescent astrocytic CRT cells induced by D-galactose exhibited increases in the levels of IL-6 and IL-8 via NF-κB activation, which are major SASP components and inflammatory cytokines. Conditioned medium prepared from senescent astrocytic CRT cells significantly promoted the viability of brain tumor cells (U373-MG and N2a). Importantly, conditioned medium greatly suppressed the cytotoxicity of U373-MG cells induced by temozolomide, and reduced the protein expression levels of neuron marker neuron-specific class III β-tubulin, but markedly increased the levels of c-Myc in N2a cells. Thus, our findings demonstrated that D-galactose treatment might mimic brain aging, and that D-galactose could contribute to brain inflammation and tumor progression through inducing the accumulation of senescent-secretory astrocytes.

• Korean Circulation Journal
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• v.54 no.6
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• pp.361-362
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• 2024

• BMB Reports
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• v.55 no.2
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• pp.92-97
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• 2022

Lysine methylation is one of the most important histone modifications that modulate chromatin structure. In the present study, the roles of the histone lysine demethylases JMJD2a and LSD1 in CK2 downregulation-mediated senescence were investigated. The ectopic expression of JMJD2a and LSD1 suppressed the induction of senescence-associated β-galactosidase activity and heterochromatin foci formation as well as the reduction of colony-forming and cell migration ability mediated by CK2 knockdown. CK2 downregulation inhibited JMJD2a and LSD1 expression by activating the mammalian target of rapamycin (mTOR)-ribosomal p70 S6 kinase (p70S6K) pathway. In addition, the down-regulation of JMJD2a and LSD1 was involved in activating the p53-p21^Cip1/WAF1-SUV39h1-trimethylation of the histone H3 Lys9 (H3K9me3) pathway in CK2-downregulated cells. Further, CK2 downregulation-mediated JMJD2a and LSD1 reduction was found to stimulate the dimethylation of Lys370 on p53 (p53K370me2) and nuclear import of SUV39h1. Therefore, this study indicated that CK2 downregulation reduces JMJD2a and LSD1 expression by activating mTOR, resulting in H3K9me3 induction by increasing the p53K370me2-dependent nuclear import of SUV39h1. These results suggest that CK2 is a potential therapeutic target for age-related diseases.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.365-371
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• 2017

Hydrogen has potential for preventive and therapeutic applications as an antioxidant. However, micro- and macroparticles of hydrogen in water disappear easily over time. In order to eliminate reactive oxygen species (ROS) related with the aging process, we used functional water containing nanoparticle hydrogen. Nanoparticle hydrogen does not disappear easily and collapse under water after long periods of time. We used murine embryonic fibroblasts that were isolated from 12.5-day embryos of C57BL/6 mice. We investigated the ability of nanoparticle hydrogen in water to suppress hydroxyurea-induced ROS production, cytotoxicity, and the accumulation of ${\beta}-galactosidase$ (an indicator of aging), and promote cell proliferation. The accumulation of ${\beta}-galactosidase$ in the cytoplasm and the appearance of abnormal nuclei were inhibited by daily treatment of cells with hydrogen water. When the aging process was accelerated by hydroxyurea-induced oxidative stress, the effect of hydrogen water was even more remarkable. Thus, this study showed the antioxidant and anti-senescence effects of hydrogen water. Nanoparticle hydrogen water is potentially a potent anti-aging agent.

• Journal of Plant Biology
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• v.32 no.3
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• pp.163-172
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• 1989

Nerium indicum has adaxial colleters on each petiole, bract, bracteole, calyx and corolla. The colleters are finger-shaped sometimes lobed structures with tall heads on short stalks. The petiolar colleters are more abundant than those on the bract, bracteole, calyx and corolla but their structure is similar. Meristematic activity in a small group of protodermal and hypodermal cells at the base of the developing leaf gives rise to the colleter that further differentiates by frequent anticlinal and periclinal divisions. Many of the colleters are vascullarized, sometimes a layer of redially elongated cells is present beneath the epithelial cells. Senescence of a colleter begins when the leaves have either completed their growth or are still expanding. In senescent colleters, the central cell cytoplasm and nuclei are considerably reduced. Thin layer chromatography of the freshly harvested exudate of colleter shows the presence of rhamnose, glucose and arabinose sugars.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.477-487
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• 1998

To clarify the activating effects of Scolopendrae corpus on immunological function, its effect on primary and secondary antibodies production in mice of various ages was investigated. Scolopendrae corpus increased the number of both antibody producing cells(anti-IgM and anti-IgG producing plaque forming cells, PFC) and phagocytic activity of peritoneal macrophage. Futhermore, these phenomena were significantly increased with aging in mice. Scolopendrae corpus also increased natural killer cell activity concerning to cancer immunology. These results suggest that Scolopendrae corpus markedly increases the reduced activity in the elderly and activates the immune response in senescence mice.

• BMB Reports
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• v.56 no.2
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• pp.84-89
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• 2023

The implications of nutrient starvation due to aging on the degeneration of the retinal pigment epithelium (RPE) is yet to be fully explored. We examined the involvement of AMPK activation in mitochondrial homeostasis and its relationship with the maintenance of a healthy mitochondrial population and epithelial characteristics of RPE cells under nutrient starvation. Nutrient starvation induced mitochondrial senescence, which led to the accumulation of reactive oxygen species (ROS) in RPE cells. As nutrient starvation persisted, RPE cells underwent pathological epithelial-mesenchymal transition (EMT) via the upregulation of TWIST1, a transcription regulator which is activated by ROS-induced NF-κB signaling. Enhanced activation of AMPK with metformin decelerated mitochondrial senescence and EMT progression through mitochondrial biogenesis, primed by activation of PGC1-α. Thus, by facilitating mitochondrial biogenesis, AMPK protects RPE cells from the loss of epithelial integrity due to the accumulation of ROS in senescent mitochondria under nutrient starvation.

• The Journal of Korean Medicine
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• v.19 no.2
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• pp.373-390
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• 1998

35 theses conducted in Korea on the topic of senescence or anti-oxidant were classified on the basis of research methods, animals used for the experiments, and research items. Evaluating these research works with respect to the Free Radical Theory, the following conclusions were reached. 1. Of the 17 theses written in the Oriental medicine aspect, three theses used a single herb, nine theses used a complex prescription, four theses concentrated on the usage of the medicinal acupuncture, and one research paper focused on using scientific components. Common objection of these papers were on the verification of the efficacy of herbs. 2. Of the 18 these written in the Western medicine aspect, five theses used a single drug, seven theses conducted a research on the changes due to senescence, and 6 papers were on variety of topics. The main focus of these works were on the mechanism and pathology related to the senescence rather than on the suppression of senescence. 3. Among the theses written in the Oriental medicine perspective, a total of 48 herbs were utilized. 26 of these herbs has a tonification function on the Kidney. Six out of nine complex prescription mentioned above has a function of tonifying the Kidney. 4. With respect to the research subjects used on the experiments, 8 theses have used Senescence-Accelerated mice, 13 theses have used Sprague-Dawley mice, and remaining 7 papers have used human or other animals. 5. These are the categorization of the research items used: the weight (11) and weight changes of the visceral organs (9), the measurement of the content of peroxide-disease (9), the measurement of enzyme vitality (21), the blood and urine test (10), the experiment concerning immune system (3), the influence on the hepatic capability of metabolizing foreign substance (3), the effect on hepatic cell protection (3), the measurement of both the suppression of Free Radical and ability to create Free Radical (2), the measurement of effect of suppresing MDA(malondialdehyde) (4), the effect of eliminating DPPH Radical (2), and experiements about the functions (2). 6. The rate of vitalization of well known anti-oxidants such as Superoxide dismutase (SOD), Protein-bound SH, Nonprotein-bound SH, Glutathione(GSH), Catalase, and etc. were tested in 17 theses. Considering the conclusions mentioned above, the theses related to the senescence published in Korea elected different animals used for experiments, research items and the methods of research, the end result seems to be a lack of objectivity. Thus, I would argue that research methods to overcome such a deficiency need to be developed systematically.