Young S. Kim

A mixture of trans, trans conjugated linoleic acid induces apoptosis in MCF-7 human breast cancer cells with reciprocal expression of Bax and Bcl-2.

The growth inhibitory effect of a mixture of trans, trans conjugated linoleic acid isomers (t, t CLA) was investigated in a human breast cancer cell line, MCF-7, with references to c9, t11 CLA, t10, c12 CLA, and linoleic acid. The t, t CLA treatment effectively induced a cytotoxic effect in a time-dependent (0-6 days) and concentration-dependent (0-40 microM) manner, as compared to the reference and control treatments. The apoptotic parameters were measured on cells treated with 40 microM t, t CLA for 4 days. The occurrence of the characteristic morphological changes and DNA fragmentation confirmed apoptosis. The t, t CLA treatment led to an increase in the level of p53 tumor suppressor protein and Bax protein, but suppressed the expression of Bcl-2 protein. In addition, cytochrome c was released from the mitochondria into the cytosol, and the activation of caspase-3 led to the cleavage of poly(ADP-ribose) polymerase (PARP). Moreover, the composition of the linoleic and arachidonic acids was decreased in cellular membranes. These findings suggest that incorporation of t, t CLA in the membrane induces a mitochondria-mediated apoptosis that can enhance the antiproliferative effect of t, t CLA in MCF-7 cells.

Superior anticarcinogenic activity of trans,trans-conjugated linoleic acid in N-methyl-N-nitrosourea-induced rat mammary tumorigenesis.

The anticarcinogenic activity of a mixture of trans,trans-conjugated linoleic acid (trans,trans-CLA) was investigated in rat mammary tumorigenesis induced by N-methyl-N-nitrosourea (MNU), with references to cis-9,trans-11-CLA and trans-10,cis-12-CLA isomers. Female, 7-week-old Sprague-Dawley rats were intraperitoneally injected with MNU (50 mg/kg of body weight) and then subjected to one of five diets (control, 1% trans,trans-CLA, 1% cis-9,trans-11-CLA, 1% trans-10,cis-12-CLA, and 1% linoleic acid; 8 rats/group) for 16 weeks. Food and water were made available ad libitum. trans,trans-CLA significantly (p < 0.05) reduced tumor incidence, number, multiplicity, and size and significantly (p < 0.05) increased apoptosis, relative to cis-9,trans-11-CLA and trans-10,cis-12-CLA. The molecular mechanism of trans,trans-CLA was elucidated by measuring apoptosis-related gene products and fatty acid composition in tumors. trans,trans-CLA led to increases in the p53 protein and Bax protein levels but suppressed the expression of Bcl-2 protein. The activation of caspase-3 led to the cleavage of poly(ADP-ribose) polymerase, which resulted in the execution of apoptosis. In addition, trans,trans-CLA reduced cytosolic phospholipase A2, cyclooxygenease-2, and peroxisome proliferator-activated receptor gamma protein levels. These results suggest that the trans,trans-CLA inhibits MNU-induced rat mammary tumorigenesis through the induction of apoptosis in conjunction with the reduction of arachidonic acid metabolites and that the efficacy of trans,trans-CLA is superior to cis-9,trans-11-CLA and trans-10,cis-12-CLA.

Attenuation of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-Induced Gap Junctional Intercellular Communication (GJIC) Inhibition in MCF-10A Cells by c9,t11-Conjugated Linoleic Acid

The protective effect of c9,t11-conjugated linoleic acid (CLA) on the inhibition of gap junctional intercellular communication (GJIC) was examined in a human mammary epithelial cell line (MCF-10A) treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), relative to t10,c12-CLA isomer. TPA inhibited GJIC in a dose-dependent and reversible manner and was associated with connexin 43 phosphorylation. Pretreatment of 20 μM c9,t11-CLA for 24 h prior to 60 nM TPA for 1 h prevented the inhibition of GJIC by reducing the phosphorylation of connexin 43 via suppressing extracellular signal-regulated kinases (ERK1/2) activation. Reactive oxygen species (ROS) accumulation by TPA was attenuated by c9,t11-CLA. The efficacy of c9,t11-CLA in protecting inhibition of GJIC, connexin 43 phosphorylation, and ROS production was superior to that of t10,c12-CLA. These results suggest that c9,t11-CLA, including t10,c12-CLA, prevents the carcinogenesis of MCF-10A cells by protecting down-regulation of GJIC during the cancer promotion stage, and lack of their toxicities could be an excellent indicator for the chemoprevention of breast cancer.

Differential inhibitory effects of conjugated linoleic acid isomers on mouse forestomach neoplasia induced by benzo(a)pyrene.

The differential anticarcinogenic activity of conjugated linoleic acid (CLA) isomers, including c9,t11-CLA, t10,c12-CLA, and t,t-CLA, was examined in a mouse forestomach carcinogenesis regimen induced by benzo(a)pyrene (BP). Female ICR mice (6-7 weeks of age, 26 +/- 1 g) were divided into six groups (30 mice/group, 5 mice/cage): control, linoleic acid, CLA, c9,t11-CLA, t10,c12-CLA, and t,t-CLA. Each mouse was orally given 0.1 mL of sample and 0.1 mL of olive oil on Monday and Wednesday and BP (2 mg in 0.2 mL of olive oil) on Friday. This cycle was repeated four times. Twenty-three weeks later, the experiment was terminated for tumor analysis. t,t-CLA significantly reduced (p < 0.05) both tumor number and tumor size per mouse, relative to CLA and c9,t11-CLA, but similar to t10,c12-CLA. Reduction in tumor incidence by t,t-CLA (84.6%) was similar to that by CLA, c9,t11-CLA, and t10,c12-CLA, but it was significantly reduced (p < 0.05), relative to 100% linoleic acid and control. t,t-CLA elevated the apoptotic index to 35%, relative to 23% for CLA, 21% for c9,t11-CLA, 29% for t10,c12-CLA, 7% for linoleic acid, and 4% for control. t,t-CLA up-regulated the expression of the Bax gene and activated caspase-3 enzymes but down-regulated expression of the Bcl-2 gene. Cytosolic phospholipase A(2) activity was not affected by the CLA isomers tested. These results suggest that t,t-CLA has superior anticarcinogenic potential on BP-induced mouse forestomach neoplasia to CLA, c9,t11-CLA, and t10,c12-CLA, via the induction of apoptosis through mitochondrial dysfunction.

Forecast of domestic air travel demand change by opening the high speed rail

In Korea, the Seoul-Busan High Speed Rail (HSR) of which length is 430.7 km is under construction with plan to complete at the end of 2011. Therefore, there will be great change at modal split of this corridor travel, especially at air travel denand. This study forecasted the air travel demand changes of Seoul-Busan and Seoul-Daegu airlines which are competitive with the HSR. The result of this study can be used for airline companies to prepare the impact and for government to adjust the domestic air transportation planning. First, studies were conducted to establish a modal split model of regional transit travel by using the travel data between Seoul and 8 regional cities where the airplane, express train and express bus are mutually competitive. For the model, abstract, Logit and neural network models were analyzed, and the best result was obtained at the neural network model. The model has an input layer, 4 hidden layers and an output layer. The input units consists of travel time, travel cost, number of service frequency and number of seats of regional transit modes such as express bus, express train and airplane, and the hidden layers have 8 neurons. Using the neural network model, the travel demands of Seoul-Busan and Seoul-Daegu airlines in the horizon year when the HSR would begin service were estimated. Due to the HSR opening, the demand of Seoul-Busan airline is forecasted to decrease by 69.5% and the demand of the Seoul-Daegu airline is forecasted to decrease by 59.0%.

Optimal Level for the Protection of Carbon Tetrachloride-induced Sprague-Dawley Rat Liver Damage by Mycelial Cultures of Lentinus edodes

The protective effects of a powder mixed with solid-cultured and liquid-cultured Lentinus edodes mycelia (2 : 1, w/w) (designate LED) with different doses of carbon tetrachloride (CCl₄) on induced hepatotoxicity in male Sprague-Dawley (SD) rats was investigated. The rats were divided into seven groups (6 rats/group) and the following substances were administered orally to each group: Vehicle (0.2 ㎖ distilled water), Control (0.2 ㎖ distilled water), LED (LED 100, 200, 300 and 400 ㎎/㎏ BW in 0.2 ㎖ distilled water), and Silymarin (200 ㎎/Kg BW in 0.2 ㎖ distilled water). After two weeks of daily administration, all groups except for the Vehiclegroup were subjected to abdominal injection with CCl₄ (CCl₄ : corn oil, 1 : 1 v/v; 0.5 ㎖/㎏ BW). One day later, blood and liver samples were collected to analyze biomarkers. All LED treatments elevated hepatic superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH peroxidase) activities, and reduced thiobarbituric reactive substances (TBARS), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), resulting in the reduction of glutamate-oxalate transaminase (GOT), glutamate-pyruvate transaminase (GPT) and lactic acid dehydrogenase (LDH) activities in plasma. These results indicate that LED effectively protected SD rat hepatotoxicity induced by CCl₄ through its antioxidative activity and reduction of some cytokines. The highest efficacy was found in LED 200 ㎎/㎏ BW, showing potential as a useful material for protection from hepatotoxicity in humans.

Mycelial Culture of Lentinus edodes Alleviates Rat Liver Toxicity Induced by Carbon Tetrachloride and Ethanol

The protective effect of a mixed powder from solid-cultured and liquid-cultured Lentinus edodes mycelia (2:1, w/w) (designate LED) on the carbon tetrachloride (CCl₄)- and ethanol-induced hepatotoxicity of male Sprague-Dawley (SD) rat was investigated. In the CCl₄-induced rat hepatotoxicity experiment, rats of 4 groups (6 rats/group) were administere with Normal (0.2 ml distilled water), Control (0.2 ml distilled water), LED (LED 200 ㎎/㎏ BW + 0.2 ml distilled water), and Silymarin (200 ㎎/㎏ BW + 0.2 ml distilled water), p.o., daily for 2 weeks. Afterwards, all groups except for the Normal group were subjected to abdominal injection with CCl₄ (CCl₄: corn oil, 1:1 v/v; 0.5 ml/㎏ BW). For the ethanol- induced rat hepatotoxicity experiment, rats were divided into 5 groups (5 rats/group): Normal; Pair-fed control (PFC); Control (ethanol); LED (ethanol + LED 200 ㎎/㎏ BW); and Silymarin (ethanol + silymarin 200 ㎎/㎏ BW). Rats of the Normal and PFC groups were fed a basal liquid diet, and rats of the Control, LED, and Silymarin groups were fed a liquid ethanol diet containing LED or Silymarin. Eight weeks later, blood and liver samples were collected to analyze biomarkers. In CCl₄-induced SD rats, LED elevated hepatic superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH peroxidase) activities and thiobarbituric reactive substances (TBARS) were reduced, resulting in the reduction of glutamate-oxalate transaminase (GOT), glutamate-pyruvate transaminase (GPT) and lactic dehydrogenase (LDH) activities in plasma. Similar results of these enzymes and biochemical markers in both liver tissues and plasma were seen in ethanol-induced hepatotoxicity of SD rats. In addition, elevated alcohol dehydrogenase (ADH) activity and reduced expression of cytochrome p450 mixed monooxygenase enzyme (CYP2E1) were seen in liver tissues from ethanol-treated rats by LED treatment. These effects of LED were similar to those of Silymarin. In in vitro experiments, LED showed antioxidant activity in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) system and mouse liver mitochondria system induced by NADPH/Fe 2+ and cumine hydroperoxide (CuOOH). These results indicate that LED protected SD rat hepatotoxicity, induced by CCl₄ and ethanol, through its antioxidative activity and might be useful as a material for protection from hepatoxicity in humans.