• Title/Summary/Keyword: In Vitro Development

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Transfer of Isolated Mitochondria to Bovine Oocytes by Microinjection (미세주입을 이용한 난자로의 분리된 미토콘드리아 전달)

  • Baek, Sang-Ki;Byun, June-Ho;Kim, Bo Gyu;Lee, A ram;Cho, Young-Soo;Kim, Ik-Sung;Seo, Gang-Mi;Chung, Se-Kyo;Lee, Joon-Hee;Woo, Dong Kyun
    • Journal of Life Science
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    • v.27 no.12
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    • pp.1445-1451
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    • 2017
  • Mitochondria play a central role in energy generation by using electron transport coupled with oxidative phosphorylation. They also participate in other important cellular functions including metabolism, apoptosis, signaling, and reactive oxygen species production. Therefore, mitochondrial dysfunction is known to contribute to a variety of human diseases. Furthermore, there are various inherited diseases of energy metabolism due to mitochondrial DNA (mtDNA) mutations. Unfortunately, therapeutic options for these inherited mtDNA diseases are extremely limited. In this regard, mitochondrial replacement techniques are taking on increased importance in developing a clinical approach to inherited mtDNA diseases. In this study, green fluorescence protein (GFP)-tagged mitochondria were isolated by differential centrifugation from a mammalian cell line. Using microinjection technique, the isolated GFP-tagged mitochondria were then transferred to bovine oocytes that were triggered for early development. During the early developmental period from bovine oocytes to blastocysts, the transferred mitochondria were observed using fluorescent microscopy. The microinjected mitochondria were dispersed rapidly into the cytoplasm of oocytes and were passed down to subsequent cells of 2-cell, 4-cell, 8-cell, morula, and blastocyst stages. Together, these results demonstrate a successful in vitro transfer of isolated mitochondria to oocytes and provide a model for mitochondrial replacement implicated in inherited mtDNA diseases and animal cloning.

Effect of Electric fusion Methods on Cell Fusion Rate and Embryo Development by Somatic Cell Nuclear Transfer in Korean Native Cattle(KNC) (한우 체세포를 이용한 핵이식에서 전기융합 방법이 융합율 및 배발달율에 미치는 영향)

  • 김은국;김정욱
    • Journal of Embryo Transfer
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    • v.18 no.3
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    • pp.171-178
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    • 2003
  • This study was conducted to investigate the effect of electric fusion methods on cell fusion rate and embryo development by somatic cell nuclear transfer in Korean Native Cattle. The KNC ear cell was cultured in vitro for confluence in serum starvation condition(DMEM+0.05% FBS) for cell confluence. The zona pellucida of IVM oocytes were partially dissection using micro pipette. Ear cells were transferred into an enucleated oocyte. The reconstructed embryos were electrically fused with Zimmermann Cell Fusion Medium(ZCFM). Nuclear transfer embryos were activated with a combination of 10${\mu}{\textrm}{m}$ calcium ionophore(5 min) and 2.0mM 6-DMAP(3 hr). The activated embryos were cultured in CR1 -aa medium contains 0.3% BSA or 10% FBS at 37$^{\circ}C$, 90% $N_2$, and 5% $CO_2$in incubator for 6 days. The fusion rates were 51.6%(chamber) and 68.9%(needle), respectively and there were significantly difference between the fusion method(P<0.05). But, lysis rates were not significantly different(10.7%, 11.5%), respectively. The cleavage rates were significantly different between the chamber method(73.2%) and needle method(80.3%), respectively(P<0.05). The rates of early embryos(2∼4cells) and blastocysts of chamber and needle methods were 54.1%, 61.1% and 18.4%, 26.3% respectively, and needle method was significantly higher than chamber method(P<0.05). But, morulae formation rate were not significantly differences between the chamber(6.7%) and needle(6.2) method(P <0.05). These result suggest that electric fusion of needle method was to be profitable for nuclear transfer embryo fusion rate, blastocyst formation rate and reduce of oocyte lysis.

Effect of OPU (Ovum Pick-Up) Duration on the Rate of Collected Ova and In Vitro Produced Blastocyst Formation (OPU(Ovum Pick-Up) 채란기간이 난자 및 수정란 생산에 미치는 영향)

  • Jin, Jong-In;Kwon, Tae-Hyeon;Choi, Byeong-Hyun;Kim, Sung-Soo;Jo, Hyun-Tae;Kong, Il-Keun
    • Journal of Embryo Transfer
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    • v.25 no.1
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    • pp.15-20
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    • 2010
  • This study was performed to identify the optimal timing for oocyte donor replacement during OPU procedure. OPU was carried out to collect oocytes from every donor at an interval of $3{\sim}4$ days (2 times a week). The collected oocytes were matured in vitro in TCM-199 supplemented with 10% FBS, 10 mg/ml of FSH and 1 mg/ml of estradiol for 24 h. After 24 h of exposure to sperm, the presumptive zygotes were cultured in CR1aa medium supplemented with 4 mg/ml of BSA for 3 days before being changed to CR1aa medium with 10% of FBS for another $3{\sim}4$ days. The mean numbers of retrieved oocytes were remained constantly up to 3 months ($6.0{\pm}0.5$, $6.2{\pm}0.7$, $5.2{\pm}0.6$), but significantly decreased at over 4 to 6 months ($3.7{\pm}0.5$, $2.8{\pm}0.4$, $1.2{\pm}0.2$) (p<0.05). The blastocyst development potential was also very similar rate from 1 to 3 months (37.2%, 40.4% and 44.6%), but significantly decreased from 4 to 6 months (24.8%, 29.3% and 28.6%, respectively) (p<0.05). The production of OPU derived embryos in periods of 1 to 3 months ($2.2{\pm}0.3$, $2.5{\pm}0.3$ and $2.3{\pm}0.4$) were significantly higher than those in 4 to 6 months ($0.9{\pm}0.2$, $0.8{\pm}0.2$ and $0.3{\pm}0.2$, respectively) (p<0.05). In conclusion, the efficient periods for the production of OPU derived embryos was until 4 months, twice per week to produce over 64 transferable embryos and then replace new donor after 3 months use. The best replacement time is 3 months and could be maximized production of OPU derived embryos.

In vitro Antioxidant and Anti-Inflammatory Activities of Ethanol Extract and Sequential Fractions of Flowers of Prunus persica in LPS-Stimulated RAW 264.7 Macrophages (복숭아꽃 에탄올 추출물과 분획물의 in vitro 항산화 효과 및 RAW 264.7 대식세포에서의 항염증 효과)

  • Kwak, Chung Shil;Choi, Hye-In
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.44 no.10
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    • pp.1439-1449
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    • 2015
  • Prunus persica Flos (PPF) were investigated for their antioxidant and anti-inflammatory activities to find a natural functional food resource preventing degenerative diseases associated with excessive oxidative stress and chronic inflammation. PPF was extracted using ethanol (EtOH) and then sequentially fractioned by hexane (Hx), dichloromethane (DM), ethyl acetate (EA), n-butanol (BtOH), and water (DW). Contents of total phenolics and flavonoids, as well as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities were measured. Anti-inflammatory effects in terms of nitric oxide (NO), prostaglandin (PG) E2, and pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-${\alpha}$ production were also measured using LPS-treated RAW 264.7 macrophages. EtOH extract showed relatively high antioxidant activity with high total phenolic (78.1 mg tannic acid/g) and flavonoid contents (55.3 mg rutin/g). EA fraction contained the highest total phenolic and flavonoid contents (394.6 mg tannic acid/g, 253.7 mg rutin/g), followed by BtOH (128.3 mg tannic acid/g, 93.1 mg rutin/g). EA and BtOH fractions and EtOH extract showed higher DPPH radical and ABTS radical scavenging activities than the others (P<0.05). In LPS-treated RAW 264.7 macrophages, EtOH extract ($200{\mu}g/mL$) showed significantly reduced (P<0.05) NO, PGE2, and TNF-${\alpha}$ production levels to 38.5%, 32.3%, and 48.9% of the control, respectively, as well as reduced iNOS and COX-2 protein expression. DM fraction ($50{\mu}g/mL$) showed significantly reduced (P<0.05) NO, PGE2, IL-6, and TNF-${\alpha}$ production levels to 43.5%, 13.3%, 38.7%, and 41.3% of the control, respectively, and EA fraction ($50{\mu}g/mL$) showed significantly reduced NO, PGE2, IL-6, and TNF-${\alpha}$ production levels to 44.8%, 22.4%, 45.7%, and 62.0% of the control, respectively. Taken together, EtOH extract of PPF showed potent antioxidant and anti-inflammatory activities, and EA and BtOH fractions showed comparatively stronger antioxidant activities while DM and EA fractions showed stronger anti-inflammatory activities. It can be concluded that EtOH extract of PPF and its fractions are good candidates as natural resources for the development of anti-oxidative and anti-inflammatory functional food products.

Comparison of Enalapril Maleate Tablets on Bioavailability and the Time Course of Inhibition of Plasma Angiotensin-Converting Enzyme (Enalapril Maleate 정제의 동등성에 관한 연구 ; 약동학적 성상 및 혈장 ACE 활성도 억제 효과)

  • Jang, In-Jin;Jang, Byung-Soo;Shin, Sang-Goo;Shin, Jae-Gook;Rho, Il-Kun;Lee, Kyeong-Hun;Park, Chan-Woong
    • The Korean Journal of Pharmacology
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    • v.26 no.2
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    • pp.219-226
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    • 1990
  • Enalapril maleate tablets of two different producers were tested for bioequivalence. Enalapril is rapidly metabolized to an active metabolite, enalaprilat which inhibits angiotensin-converting enzyme (ACE). The pharmacokinetics of enalapril maleate and the time course of inhibition of plasma ACE activity after administration of the drugs were studied. Two single doses of 10mg each of enalapril maleate were administered orally to twelve male volunteers in a balanced, randomized, two-way crossover investigation. Plasma enalaprilat concentrations were determined over a 23-hour after the dose by enzyme inhibition assay and enalapril by the same method following in vitro hydrolysis. Urinary recoveries of enalapril and enalaprilat were determined for the calculation of renal clearance. Plasma ACE activity was determined by an enzyme assay. Peak plasma levels of enalapril were observed about 1 hour after the doses, and practically all enalapril had disappeared from plasma within 6 hour. Peak enalapril concentrations of both formulations were almost identical ($Vasotec^{\circledR}$, 61.38 ng/ml; $Beartec^{\circledR}$, 64.27 ng/ml). The values of the pharmacokinetic parameters of enalaprilat computed for $Vasotec^{\circledR}$ and $Beartec^{\circledR}$ tablets are presented in that order; area under the curve=330.63:320.96 $ng{\cdot}hr/ml$; peak concentration=38.63:39.43 ng/ml; time to peak=3.83:4.08 hour; elimination half-life=3.95:3.92 hours. No statistically significant difference was detected when area under the curve and all other parameters were compared. Using criteria of 95% confidence interval for the comparison of these parameters, only the upper limits of area under the curve and time to peak of enalapril were over 120%. All the parameters of enalaprilat were acceptable. Percent inhibition of plasma ACE to plasma enalaprilat concentration showed the sigmoid concentration-inhibition relationship. Time courses of plasma ACE inhibition after the administration of both formulations were quite similar. The formulations were found to be equivalent when compared on the premise that no significant difference was detected when pharmacokientic parameters and inhibition of ACE activity were compared, based on the confidence limits analysis.

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Development of assay method for the activities of new compounds, and the effect of several fungicides against spore germination, adhesion, and myceial growth of Colletotrichum sp. causing red pepper anthracnose (고추 탄저병균의 포자 발아와 부착, 균사 생장에 미치는 화합물의 활성 검정법 확립 및 살균제의 효과)

  • Kim, Jae-Jeung;Kim, Joon-Tae;Park, Sung-Woo;Park, Eun-Suk;Kim, Heung-Tae
    • The Korean Journal of Pesticide Science
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    • v.7 no.3
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    • pp.159-168
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    • 2003
  • With microtiter plate, the assay method was developed for detecting the fungicidal activity of new compounds against spore germination, spore adhesion and mycelial growth of Colletotrichum sp. JC24 cal1Sing red pepper anthracnose. Also, the effects of some commercialized fungicides on fungal development like above mentioned were investigated by measuring the optical density of mycelia grown into wells of microtiter plate. For the standardization of assay method, some factors, such as the treatment of MTT and/or propanol, inodulum density and incubation period, affecting on mycelial optical density were investigated. For obtaining precise and consistent mycelial optical density, it was necessary the treatment of MTT for 12 hrs and propanol for 1 hr. inoculum density adjusted to $1\times10^5$ spores/mL and incubation period for 36 hrs at $25^{\circ}C$. For fungicidal activities, 6 protective fungicides, 6 ones inhibiting sterol biosynthesis, and one inhibiting respiration were used in this study. While mancozeb, chlorothalonil and dithianon among 6 protective fungicides inhibited strongly spore germination, adhesion, and mycelial growth at $6.25{\mu}g/mL$, propineb, iminoctadine and fluazinam inhibited intermediately spore germination and mycelial growth at $100{\mu}g/mL$. Washing above 3 fungicides with new PD broth, their activity against spore adhesion decreased. With hexaconazole, tebuconazole and myclobutanil, the tendency of the activity against fungal differentiation of the early infection stage was similar to the latter group of protective fungicides, showing the decrease of the inhibitory activity against spore adhesion by washing 2 hrs after incubation. However, kresoxim-methyl inhibited spore adhesion distinctly, depending on the applied concentrations. Based on these results, it might be able to assess the fungicidal activity of many compounds against spore germination, adhesion and mycelial growth by the use of microtiter plate in vitro. Using the assay developed in this report, it was possible to investigate the inhibitory activity of some commercialized fungicides, too.

A STUDY ON THE MEASUREMENT OF THE IMPLANT STABILITY USING RESONANCE FREQUENCY ANALYSIS (공진 주파수 분석법에 의한 임플랜트의 안정성 측정에 관한 연구)

  • Park Cheol;Lim Ju-Hwan;Cho In-Ho;Lim Heon-Song
    • The Journal of Korean Academy of Prosthodontics
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    • v.41 no.2
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    • pp.182-206
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    • 2003
  • Statement of problem : Successful osseointegration of endosseous threaded implants is dependent on many factors. These may include the surface characteristics and gross geometry of implants, the quality and quantity of bone where implants are placed, and the magnitude and direction of stress in functional occlusion. Therefore clinical quantitative measurement of primary stability at placement and functional state of implant may play a role in prediction of possible clinical symptoms and the renovation of implant geometry, types and surface characteristic according to each patients conditions. Ultimately, it may increase success rate of implants. Purpose : Many available non-invasive techniques used for the clinical measurement of implant stability and osseointegration include percussion, radiography, the $Periotest^{(R)}$, Dental Fine $Tester^{(R)}$ and so on. There is, however, relatively little research undertaken to standardize quantitative measurement of stability of implant and osseointegration due to the various clinical applications performed by each individual operator. Therefore, in order to develop non-invasive experimental method to measure stability of implant quantitatively, the resonance frequency analyzer to measure the natural frequency of specific substance was developed in the procedure of this study. Material & method : To test the stability of the resonance frequency analyzer developed in this study, following methods and materials were used : 1) In-vitro study: the implant was placed in both epoxy resin of which physical properties are similar to the bone stiffness of human and fresh cow rib bone specimen. Then the resonance frequency values of them were measured and analyzed. In an attempt to test the reliability of the data gathered with the resonance frequency analyzer, comparative analysis with the data from the Periotest was conducted. 2) In-vivo study: the implants were inserted into the tibiae of 10 New Zealand rabbits and the resonance frequency value of them with connected abutments at healing time are measured immediately after insertion and gauged every 4 weeks for 16 weeks. Results : Results from these studies were such as follows : The same length implants placed in Hot Melt showed the repetitive resonance frequency values. As the length of abutment increased, the resonance frequency value changed significantly (p<0.01). As the thickness of transducer increased in order of 0.5, 1.0 and 2.0 mm, the resonance frequency value significantly increased (p<0.05). The implants placed in PL-2 and epoxy resin with different exposure degree resulted in the increase of resonance frequency value as the exposure degree of implants and the length of abutment decreased. In comparative experiment based on physical properties, as the thickness of transducer increased, the resonance frequency value increased significantly(p<0.01). As the stiffness of substances where implants were placed increased, and the effective length of implants decreased, the resonance frequencies value increased significantly (p<0.05). In the experiment with cow rib bone specimen, the increase of the length of abutment resulted in significant difference between the results from resonance frequency analyzer and the $Periotest^{(R)}$. There was no difference with significant meaning in the comparison based on the direction of measurement between the resonance frequency value and the $Periotest^{(R)}$ value (p<0.05). In-vivo experiment resulted in repetitive patternes of resonance frequency. As the time elapsed, the resonance frequency value increased significantly with the exception of 4th and 8th week (p<0.05). Conclusion : The development of resonance frequency analyzer is an attempt to standardize the quantitative measurement of stability of implant and osseointegration and compensate for the reliability of data from other non-invasive measuring devices It is considered that further research is needed to improve the efficiency of clinical application of resonance frequency analyzer. In addition, further investigation is warranted on the standardized quantitative analysis of the stability of implant.

The Ability of Anti-tumor Necrosis Factor Alpha(TNF-${\alpha}$) Antibodies Produced in Sheep Colostrums

  • Yun, Sung-Seob
    • 한국유가공학회:학술대회논문집
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    • 2007.09a
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    • pp.49-58
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    • 2007
  • Inflammatory process leads to the well-known mucosal damage and therefore a further disturbance of the epithelial barrier function, resulting abnormal intestinal wall function, even further accelerating the inflammatory process[1]. Despite of the records, etiology and pathogenesis of IBD remain rather unclear. There are many studies over the past couple of years have led to great advanced in understanding the inflammatory bowel disease(IBD) and their underlying pathophysiologic mechanisms. From the current understanding, it is likely that chronic inflammation in IBD is due to aggressive cellular immune responses including increased serum concentrations of different cytokines. Therefore, targeted molecules can be specifically eliminated in their expression directly on the transcriptional level. Interesting therapeutic trials are expected against adhesion molecules and pro-inflammatory cytokines such as TNF-${\alpha}$. The future development of immune therapies in IBD therefore holds great promises for better treatment modalities of IBD but will also open important new insights into a further understanding of inflammation pathophysiology. Treatment of cytokine inhibitors such as Immunex(Enbrel) and J&J/Centocor(Remicade) which are mouse-derived monoclonal antibodies have been shown in several studies to modulate the symptoms of patients, however, theses TNF inhibitors also have an adverse effect immune-related problems and also are costly and must be administered by injection. Because of the eventual development of unwanted side effects, these two products are used in only a select patient population. The present study was performed to elucidate the ability of TNF-${\alpha}$ antibodies produced in sheep colostrums to neutralize TNF-${\alpha}$ action in a cell-based bioassay and in a small animal model of intestinal inflammation. In vitro study, inhibitory effect of anti-TNF-${\alpha}$ antibody from the sheep was determined by cell bioassay. The antibody from the sheep at 1 in 10,000 dilution was able to completely inhibit TNF-${\alpha}$ activity in the cell bioassay. The antibodies from the same sheep, but different milkings, exhibited some variability in inhibition of TNF-${\alpha}$ activity, but were all greater than the control sample. In vivo study, the degree of inflammation was severe to experiment, despite of the initial pilot trial, main trial 1 was unable to figure out of any effect of antibody to reduce the impact of PAF and LPS. Main rat trial 2 resulted no significant symptoms like characteristic acute diarrhea and weight loss of colitis. This study suggested that colostrums from sheep immunized against TNF-${\alpha}$ significantly inhibited TNF-${\alpha}$ bioactivity in the cell based assay. And the higher than anticipated variability in the two animal models precluded assessment of the ability of antibody to prevent TNF-${\alpha}$ induced intestinal damage in the intact animal. Further study will require to find out an alternative animal model, which is more acceptable to test anti-TNF-${\alpha}$ IgA therapy for reducing the impact of inflammation on gut dysfunction. And subsequent pre-clinical and clinical testing also need generation of more antibody as current supplies are low.

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Microenvironments and Cellular Proliferation Affected by Oxygen Concentration in Non-Small Cell Lung Cancer Cell Line (비소세포폐암주에서 산소 농도에 따른 미세 배양 환경과 세포 증식능)

  • Shin, Jong Wook;Jeon, Eun Ju;Kwak, Hee Won;Song, Ju Han;Lee, Young Woo;Jeong, Jae Woo;Choi, Jae Cheol;Kim, Jae-Yeol;Park, In Won;Choi, Byoung Whui
    • Tuberculosis and Respiratory Diseases
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    • v.63 no.3
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    • pp.242-250
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    • 2007
  • Background: Abnormal angiogenesis can induce hypoxia within a highly proliferating tumor mass, and these hypoxic conditions can in turn create clinical problems, such as resistance to chemotherapy. However, the mechanism by which hypoxia induces these changes has not yet been determined. Therefore, this study was conducted to determine how hypoxia induces changes in cell viability and extracellular microenvironments in an in vitro culture system using non-small cell lung cancer cells. Methods: The non-small cell lung cancer cell line, A549 was cultured in DMEM or RPMI-1640 media that contained fetal bovine serum. A decrease in the oxygen tension of the media that contained the culture was then induced in a hypoxia microchamber using a $CO_2-N_2$ gas mixture. A gas analysis and an MTT assay were then conducted. Results: (1) The decrease in oxygen tension was checked the anaerobic gas mixture for 30 min and then reoxygenation was induced by adding a 5% $CO_2-room$ air gas mixture to the chamber. (2) Purging with the anaerobic gas mixture was found to decrease the further oxygen tension of cell culture media. (3) The low oxygen tension resulted in a low pH, lactic acidosis and a decreased glucose concentration in the media. (4) The decrease in glucose concentration that was observed as a result of hypoxia was markedly different when different types of media were evaluated. (5) The decrease in oxygen tension inhibited proliferation of A549 cells. Conclusion: These data suggests that tumor hypoxia is associated with acidosis and hypoglycemia, which have been implicated in the development of resistance to chemotherapy and radiotherapy.

Development of Natural Antioxidants and Whitening Agents for Cosmeceuticals

  • Kim, Jong-Pyung
    • Proceedings of the Korean Society of Applied Pharmacology
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    • 2007.11a
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    • pp.79-92
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    • 2007
  • Oxidative stress have known to be a risk factor for the degenerative processes and closely related to a lot of diseases. It is well established that antioxidants are good in protection and therapeutic means against oxidative damage. There is increasing interest in natural antioxidants and many natural antioxidants have been found and utilized as the possible protection for various diseases and skin aging. We have screened natural antioxidant agents for cosmeceuticals, nutraceuticals, and drugs as therapeutic and preventive means against oxidative stress, and have developed a number of novel antioxidants from various natural sources. A novel melanin synthesis inhibitor, Melanocin A, isolated from the metabolite of a fungal strain Eupenicillium shearii F80695 inhibited mushroom tyrosinase and melanin biosynthesis of B16 melanoma cells with $IC_{50}$ value of 9.0 nM and MIC value of $0.9\;{\mu}M$, respectively. Melanocin A also exhibited potent antioxidant activity by scavenging of DPPH and superoxide anion radicals. UV was found to increase the level of hydrogen peroxides and other reactive oxygen species (ROS) in skin tissues. This increase in ROS may not only alter the structure and function of many genes and proteins directly but may also modulate their expressions through signal transduction pathways and, ultimately, lead to skin damage. We investigated the effect of Melanocin A on UV-induced premature skin aging. Firstly, the effect of Melanocin A on UV-induced matrix metalloproteinase (MMP)-9 expression in an immortalized human keratinocyte cell line, HaCaT in vitro was investigated. Acute UV irradiation induced MMP-9 expression at both the mRNA and protein levels and Melanocin A suppressed this expression in a dose-dependent manner. We then investigated UV-induced skin changes in hairless mice in vivo by Melanocin A. Chronic exposure of hairless mouse dorsal skin to UV increased skin thickness and induced wrinkle formation and the gelatinase activities of MMP-2 and MMP-9. Moreover, Melanocin A significantly suppressed UV-induced morphologic skin changes and MMP-2 and MMP-9 expression. These results show that Melanocin A can prevent the harmful effects of UV that lead to skin aging. Therefore, we suggest that Melanocin A should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging. Terrein is a bioactive fungal metabolite isolated from Penicillium species. Terrein has a relatively simple structure and can be easily synthesized. However, the biologic effects of terrein are comparatively unknown. We found for the first time that terrein potently inhibit melanin production in melanocytes and has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 mM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrain treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrain reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.

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