• Toxicological Research
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• v.23 no.4
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• pp.311-319
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• 2007

Elevated blood levels of homocysteine (a sulfur-containing amino acid) have been linked to increased risk of cerebrovascular disease including Alzheimer's disease. A recent study suggests that elevated homocysteine levels may lead to replicative senescence in vitro called 'permanent arrest of cell cycle' caused by oxidative stress. In this study, serum homocysteine level in rat was reduced by Lentinus edodes-powder diet, resulting in the reduced level of oxidative stress in rat brain. In addition, homocysteine-induced replicative senescence treated with or without Lentinus edodes-powder was analyzed by population doubling in vitro. The Lentinus edodes-powder induced a increased number of population doubling in primary neuron cell isolated from rat-cerebral cortex. This indicates that Lentinus edodes-powder would delay a homocysteine-induced aging of neuron cells in brain, showing a possible role in preventing cerebrovascular diseases including Alzheimer's disease.

• KSBB Journal
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• v.11 no.2
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• pp.254-261
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• 1996

Attenuated varicella-zoster virus (VZV) was propagated in human lung fibroblast (HLF) cells Among media tested in this work, DMEM was the best medium for the growth of HLF cells. Because HLF was a normal finite cell line, cell growth late was dependent on the age of HLF cells. When the population doubling level (PDL) was higher than 46, apoptosis of HLF cells started and cell growth rate decreased. The optimum temperature for the cell growth and virus propagation in the T-flask culture was $37^{\circ}C$. In a microcarrier culture system in which Cytodex-3 was used for the VZV propagation in spinner vessels, the yield of plaque forming cells was lower than that in the T-flask culture. The relatively high shear environment near microcarriers was thought to cause the low yield of VZV in the microcarrier culture system.

• Reproductive and Developmental Biology
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• v.28 no.1
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• pp.7-12
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• 2004

This study was performed to establish the effective culture condition for the establishment of clonal lines from porcine fetal fibroblast cells. Fibroblasts derived from a pig fetus (Day 50) were cultured and passaged two times before use. A single cell was seeded in 96-well plates, cultured in medium supplemented with different concentrations of FBS, catalase or $\beta$-mercaptoethanol ($\beta$ME), and classified by cell size and morphology. Cells were passaged two times into 4-well dish before freezing. The establishment efficiencies were not different among different concentrations of FBS (0.3 to 5.1%). However, population doubling time (PDT) was significantly decreased by increasing the FBS concentration (P＜0.05). The establishment efficiency of $\beta$ME-added group (10.4%) was significantly higher than those of catalase-added and control groups (3.5%, and 3.5%, respectively, p＜0.05), and PDT was significantly decreased (23.6 vs 28.1, and 25.5 h, respectively, p＜0.05). However, catalase did not show a positive effect on the establishment efficiency. Cell size and morphology did not affect the establishment efficiency and PDT of clonal lines. The result of present study shows that the establishment efficiency of clonal cell lines can be enhanced by the culture in media supplemented with 30% FBS and $\beta$ME.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.2
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• pp.89-95
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• 1999

This study investigates the population model of the spread of HIV/AIDS which the infection is generated by an infectious individual in a population of susceptible. A mathematical model is presented for the transmission dynamics of HIV infection within the communities of homosexual males. The pattern on the epidemic character of HIV, the causative agent of AIDS, was analysed by the mathematical model of AIDS system which is derived according to the ecological relationship between five epidemilogic states of individuals. The computer simulation was performed using real data and the following conclusions are drawn on the basis of the simulations. 1. The model structure and the algorithm described n the thesis is good. 2. In proportion to increase Ro, the population of AIDS patient increases and the time of its widespread reaches earlier. 3. The AIDS patients will be maximum between 7 and 21 years after an attack of AIDS and widespread between 10 and 20 years. 4. Considering the properties of the incubation periods, the maximum number of infected person is increased, and the attack rate is decreased.

• The Journal of Korean Medicine
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• v.25 no.1
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• pp.49-59
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• 2004

Objectives: This paper is to investigate what effects Yeonryunggobondan and Palmijihwangtang have on postponing senility in rat fibroblasts, heart-endothelial cells, mesangial cells. Methods: 1. In vitro Yeonryunggobondan and Palmijihwangtang controlled the growth of fibroblasts, heart-endothelial cells, mesangial cells, extended the PDT of them. 2. After feeding rats the drugs for 2 months, the fibroblasts, heart-endothelial cells, mesangial cells were cultured. Results: 1) In fibroblasts the PDN was incresed and the PDT was decreased at passage-1, 2 by Yeonryunggobondan and Palmijihwangtang(p<0.05). 2) In heart-endothelial cells the PDN was incresed and the PDT was decreased at passage 8 by Yeonryunggobondan and Palmijihwangtang(p<0.05). 3) In mesangial cells the PDN was increased and the PDT was decreased at passage 4 by Yeonryunggobondan, the PDN was incresed at passage 4 by Palmijihwangtang(p<0.05). Conclusions: It is concluded that both Yeonryunggobondan and Palmijihwangtang maybe be conductive to protect and delay the senescence of rat fibroblasts, heart-endothelial cells, mesangial cells.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7575-7582
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• 2015

Cyclin E, a key coordinator of the G1 to S transition in the cell cycle, may be deregulated in several malignancies, including breast cancer. The most significant aberration in cyclin E is its elastase mediated proteolytic cleavage into tumor specific low molecular weight isoforms (LMW-Es). LMW-Es are biochemically hyperactive and biologically drive tumorigenesis in transgenic mouse models. Additionally, expression of LMW-Es has been correlated with poor survival in breast cancer cases. Here we determine whether expression of LMW-Es in a breast cancer cell line that is naturally devoid of these deregulated forms would alter their progression through each phase of the cell cycle. The results revealed that LMW-Es expression resulted in an increased doubling time, concomitant with a predominant increase in the population in the S phase of the cell cycle. Moreover, downregulation of p53 in LMW-Es cells resulted in additional shortening of the doubling time and enrichment of cells in the S and G2/M phases of the cell cycle. Furthermore, expression of LMW-Es sensitized cells to ${\beta}$-estradiol (E2) mediated growth and changed expression patterns of estrogen receptor and Bcl-2. Intriguingly, expression of LMW-Es could surpass anti-apoptotic effects raised by p53 upregulation. Taken together these studies suggest that overexpression of LMW-Es in collaboration with p53 loss results in altered g rowth properties of MCF-7 cells, enhancing the oncogenic activity of these ER positive breast cancer cells.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.4
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• pp.588-595
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• 2013

Mesenchymal stem cells (MSCs) are often known to have a therapeutic potential in the cell-mediated repair for fatal or incurable diseases. In this study, canine umbilical cord MSCs (cUC-MSCs) were isolated from umbilical cord matrix (n = 3) and subjected to proliferative culture for 5 consecutive passages. The cells at each passage were characterized for multipotent MSC properties such as proliferation kinetics, expression patterns of MSC surface markers and self-renewal associated markers, and chondrogenic differentiation. In results, the proliferation of the cells as determined by the cumulative population doubling level was observed at its peak on passage 3 and stopped after passage 5, whereas cell doubling time dramatically increased after passage 4. Expression of MSC surface markers (CD44, CD54, CD61, CD80, CD90 and Flk-1), molecule (HMGA2) and pluripotent markers (sox2, nanog) associated with self-renewal was negatively correlated with the number of passages. However, MSC surface marker (CD105) and pluripotent marker (Oct3/4) decreased with increasing the number of subpassage. cUC-MSCs at passage 1 to 5 underwent chondrogenesis under specific culture conditions, but percentage of chondrogenic differentiation decreased with increasing the number of subpassage. Collectively, the present study suggested that sequential subpassage could affect multipotent properties of cUC-MSCs and needs to be addressed before clinical applications.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1338-1343
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• 2004

The Debao pony ear marginal tissue fibroblast cell line (NDPEM 2/2) was uccessfully established using either primary explant technique or collagenase technique. The characterizations of the cell line were identified as following: the cells were adherent and of density limitation; population doubling time (PDT) of cells made with the two techniques were 35.9 h and 48 h, respectively; chromosome analysis showed that the frequency of cell chromosome number to be 2n=64 was 91.3%-92.8%. Confirmed by isoenzyme analysis, this cell line had no cross- contamination. Tests for microbial contamination from bacteria, fungi, virus or mycoplasma were negative. This newly established cell line meets all the standard quality controls of ATCC. It will provide a precious genetic resource for the conservation of the Debao pony breed, as well as effective experimental material for genetic studies on Debao ponies.

• Tuberculosis and Respiratory Diseases
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• v.79 no.4
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• pp.248-256
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• 2016

Somatic mutations that lead to hyperactivation of epidermal growth factor receptor (EGFR) signaling are detected in approximately 50% of lung adenocarcinoma in people from the Far East population and tyrosine kinase inhibitors are now the standard first line treatment for advanced disease. They have led to a doubling of progression-free survival and an increase in overall survival by more than 2 years. However, emergence of resistant clones has become the primary cause for treatment failure, and has created a new challenge in the daily management of patients with EGFR mutations. Identification of mechanisms leading to inhibitor resistance has led to new therapeutic modalities, some of which have now been adapted for patients with unsuccessful tyrosine kinase inhibitor treatment. In this review, we describe mechanisms of tyrosine kinase inhibitor resistance and the available strategies to overcoming resistance.

• The Korean Journal of Zoology
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• v.34 no.2
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• pp.148-158
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• 1991

The purpose of this research was to establish the culture condition for dissociated submandibu -lar gland (SG) cells. After trypsin digestion of SG from 3-4 weeks old mice, dissociated cells were cultured in 1OO/o fetal bovine serum-Dulbecco's modified Eagle's medium (FBS-DME) or 0.5-2% low protein serum replacement-DME (LPSR-DME) on plastic surface to form monolayer. The effects of FBS, LPSR and hormones on the growth and function of cultured SG cells were examined. SG cells dissociated by enzyme were successfully cultured and were characterized as epithelial-like cells by light and electron microscope. The maximal DNA synthesis of cultured SG cells was achieved by DME containing 5-10% FBS. The same results were obtained when the effects of LPSR on cell proliferation were examined up to a LPSR concentration of 2%. SG cells cultured in 20/o LPSR-DME expressed a population doubling time of 42.5 hrs and a saturation density of 1.2 $\times$10 5cell/cm$^2$. Dihydrotestosterone (DHT) in medium did not influence on the DNA synthesis of the cultured SG cells, but stimulated protein synthesis of the SG cells. Thyroxine (T4) stimulated protein synthesis of the SCI cells markedly in a dose-dependent fashion. EGF secretion by the cultured SG cells increased significandy by DHT and or T4 trearment. This finding indicated that secretion of EGF by the SG cells was under the control of the hormones such as androgen and thyroid hormones. It seems to be that the culture condition described here can be used as a useful tool for further research on the SCI cells.