• Toxicological Research
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• 제23권4호
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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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• 제11권2호
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• pp.254-261
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• 1996

수두 바이 러스(Varicella-zoster virus, VZV) 백신을 생산하기 위하여 약독화된 수두 바이러스 주인 Oka 주를 사용하여 정상세포인 인체 폐세 포(human lung fibroblast cells)로부터 수두 바이 러스 생산조건을 검토하였다. 숙주세포의 배양을 위 한 최적 성장배지로는 DMEM이 조사된 배지 중에 서는 가장 좋음을 알 수 있었으며 숙주세포의 성장율은 세포 age의 지표인 population doubling level (PDL) 이 46 이상인 경우 낮아지는 것무로 확인되 었으며 따라서 수두바이러스 생산을 위해서는 PDL 4 46 이하의 young cell을 사용해야 할 것으로 사료된 다 한편 수두바이러스 생산을 위한 최적 증식조건 으로는 배양온도 $37^{\circ}C$, 혈청농도 2%, MOl 1:5였다. 숙주세포를 대량배양하기 위한 기본조건을 검토 하기 위하여 미 럽담체 (Cytodex-3)를 이용한 spm­n ner flask culture를 시행하였다. 미럽담체에서의 숙 주세포 성장은 T -flask와 비하여 별다른 차이가 없었으나 VZV의 증식은 T-flask 배양에서보다 훨씬 낮았다. 이는 미립담체배양에서의 높은 전단응력 과 미립담체끼리의 영김현상 때문으로 생각된다.

• Reproductive and Developmental Biology
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• 제28권1호
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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.

• 대한전기학회논문지:전력기술부문A
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• 제48권2호
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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.

• 대한한의학회지
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• 제25권1호
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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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• 제16권17호
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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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• 제26권4호
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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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• 제17권10호
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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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• 제79권4호
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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.

• 한국동물학회지
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• 제34권2호
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• pp.148-158
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• 1991

마우스의 악하선 세포를 배양하기 위하여 악하선 조직으로부터 세포를 분리하는 조건과 분리된 세포의 배양조건을 조사하였다. 세포분리에는 0.25% trypsin을 사용하였으며 배양액은 여러 농도의 fetal bovine serum (FBS) 또는 low protein serum replacement(LPSR)가 첨가된 Dulbecco's modified Eagle's medium(DME) 이었다. 배양된 세포의 대부분 상피형 세포로 확인 되었으며, 배양시 5-10%의 FBS를 첨가하였을 경우에 가장 높은 DNA합성능을 보였으나 이보다 높은 농도의 FBS 첨가시에는 오히려 DNA 합성능이 저하되었다. 혈청 대체물인 LPSR 첨가에 의한 악하선 세포를 배양 했을 때 population doubling time은 42.5 시간이었고 세포의 포화밀도는 1.2 $\times$10 5 cells / $cm^2$이었다. Dihydrotestosterone (DHT)은 악하선 배양세포의 DNA 합성에 관여하지 않거나, 관여한다면 DNA 합성을 억제하는 것으로 보였다. 이에 반해 Thyroxine (T4)은 악하선 배양세포의 DNA 합성을 현저히 증가시켰다. T4와 DHT 모두다 배양세포의 단백질 합성능을 증가시켰다. 또한 이 호르몬들이 악하선 배양세포의 epidermal growth factor(EGF) 분비를 증가시킨 결과는 DHT와 T4는 악하선 세포의 EGF 생산 뿐만 아니라 EGF 분비의 조절에도 관련되어 있음을 시사한다. 본 실험에서 정해진 악하선 세포의 배양조건은 악하선 세포의 증식과 기능의 변조를 탐구하는데 유용하게 응용될 수 있을 것으로 생각된다.