• Asian-Australasian Journal of Animal Sciences
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• 제20권10호
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• pp.1525-1538
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• 2007

Because of the increasing evidence of potential benefits of conjugated linoleic acid (CLA) on human health, there is a need to investigate its status in commercial dairies and develop feeding strategies to enhance the content and supply of CLA in milk and milk products. A two-year experiment was conducted to study the status of milk fat c-9, t-11 CLA on four selected commercial dairy farms in Utah (two) and Idaho (two), USA. Farms A and C grazed cows on pasture and supplemented with 7.0 kg/cow per day of their respective grain mixes during summer, while conserved forage and grain mix was fed during winter. Farm B fed a total mixed diet all year, with 10% of diet dry matter as fresh cut pasture during summer. Farm D had 1/3 of its cows grazed on pasture and supplemented with a total mixed diet during summer, while the rest were fed a total mixed diet. All cows in Farm D were fed a total mixed diet during winter. Farms A, B, C, and D had on average 80, 400, 150, and 500 milking cows, respectively, with Holstein or its crosses as the major breed. On a year-round basis, Farms A and C produced milk with 60% or more milk fat c-9, t-11 CLA and transvaccenic acid (TVA) contents than Farm B. Similarly, Farm D produced 30% or more c-9, t-11 CLA and TVA in milk than Farm B. Milk fat content of CLA and TVA was 150-200% more during summer compared with winter. Individual cows varied from 0.16 to 2.22% in milk fat c-9, t-11 CLA contents and 89% of the cows had c-9, t-11 CLA contents between 0.3 and 1.0% of milk fat. Individual cow variation was larger on Farms A and C compared with Farm D, with least variation on Farm B. Variation was larger in summer than in winter. The bulk tank milk c-9, t-11 CLA content varied from 0.27 to 1.35% of milk fat. Cows on Farms A and C produced similar or higher amounts of milk fat c-9, t-11 CLA on a daily basis even though their milk yield was lowest among the dairies. Concentration and supplies of c-9, t-11 CLA and TVA were highest from June through September and lowest from February through April, which should be the months for targeting improvement in the content and supply of milk fat c-9, t-11 CLA and TVA.

• Toxicological Research
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• 제23권3호
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• pp.223-229
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• 2007

Conjugated linoleic acid (CLA) has been recently reported to have an anti-obesity effect in animals and humans. The objective of this study was to investigate effects of diglyceride (DG)-CLA on proliferation and differentiation of 3T3-L1 preadipocytes. Cell proliferation was determined using WST-8 analysis and cell differentiation was determined by glycerol-3-phosphate dehydrogenase (GPDH) activity. Lipid accumulation in differentiating 3T3-L1 cells was determined by Oil red O staining. There were four experimental groups including vehicle control (DMSO), CLA, triglyceride (TG)-CLA, and DG-CLA. Treatments of CLA, TG-CLA, and DG-CLA at the concentrations of $10{\sim}1000{\mu}g/ml$ reduced proliferation of preconfluent 3T3-L1 cells in a dose-dependent manner. Among them CLA was the most effective in the proliferation inhibition of preconfluent 3T3-L1 cells with increasing concentrations. Treatments of CLA and DG-CLA at the concentration of $100{\mu}g/ml$ significantly inhibited differentiation of postconfluent 3T3-L1 cells as measured by GPOH activity (p<0.05). In addition, treatments of CLA, TG-CLA, and DG-CLA effectively inhibited lipid accumulation during differentiation of 3T3-L 1 cells. OG-CLA had the most inhibitory effect on the differentiation and lipid accumulation. These results suggest that the compounds including CLA have a respectable anti-obesity effect and that consumption of DG-CLA as a dietary oil may give a benefit for controlling overweight in humans.

• 한국임상수의학회지
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• 제20권4호
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• pp.437-442
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• 2003

CLA를 급여시킨 돼지에 있어 말초 혈액 세포의 변화와 탐식세포의 탐식반응을 조사하였다. 100일령, 평균체 중 80kg인 거세 수퇘지에게 10t-l2c CLA와 CLA mixture를 각각 사료 중에 5% 첨가하여 총 4주간에 걸쳐 자유급여 시켰다. 급여 전 (0주), 급여 2주후, 4주후 그리고 급여 중지 후인 5주차에 각각 혈액세포 수치(PCV 백혈구수 및 백혈구 감별계산치)의 변화와 탐식세포의 탐식활성을 측정하였다. CLA의 급여 따른 PCV의 수치에 있어서는 아무런 변화가 없었다. 그러나 10t-l2c CLA 또는 CLA mixture가 함유된 사료를 급여한 돼지에 있어서 CLA를 급여하지 않은 돼지에 비해 백혈구수 특히 호중구 수가 현저히 증가하였다. 말초혈액 단핵구세포(mononuclear cells; MNC)와 다형핵백혈구(polymorphonuclear cells; PMN)의 탐식능를 유세포분석기로 분석한 결과, 10t-l2c CLA 또는 CLA mixture 급여와 상관없이 MNC와 단구세포들(monocyte-rich cells)의 탐식능에는 변화가 없었다. 그러나 PMN의 탐식 활성은 CLA 무급여 대조돼지들에 비해 CLA 급여군은 2주에서 5주차에 걸쳐 증가된 탐식능를 나타내었다. 이상의 결과로부터 돼지에 CLA 급여는 호중구수 증가와 호중구 탐식능 증가를 유도할 수 있음을 제시하였으며 향후 생체방어 증강을 위해 CLA를 임상적으로 투여할 수 있을 것으로 보인다.

• Journal of Nutrition and Health
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• 제37권9호
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• pp.763-770
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• 2004

This study was designed to compare the anti-carcinogenic effect of conjugated linoleic acid isomers on tumor incidence, cell proliferation and the levels of thromboxane (TX) B$_2$, prostaglandin (PG) E$_2$ and 1,2-diacylglycerol (DAG), and the related enzyme expression of cyclooxygenase (COX)-2 and protein kinase C (PKC) in colonic mucosa of 1,2-dimethy- lhydrazine (DMH) -treated rats. One hundred eight male Sprague Dawley rats were randomly divided into 3 groups depending on the types of CLA isomers, i.e. control group (no CLA contained), c9t11 group (cis-9, trans-11 CLA contained), and t10c12 group (trans-10, cis-12 CLA contained). The experimental diet was composed of protein at 20%, carbohydrate at 56.2%, and fat at 14.5% including 1.0% CLA isomers by weight. The experimental diet was fed for 30 weeks with the initiation of intramuscular injection of DMH, which was injected twice a week for 6 weeks to give total dose of 180 mg per kg body weight. Two CLA isomers (c9, t11, t10, c12) significantly reduced tumor incidence and cell proliferation by reducing the protein expression of COX-2 and PKC, and the level of TXB$_2$, PGE$_2$, and DAG in colonic mucosa. However, there was no significant difference in anti-carcinogenic effect between c9t11-CLA and t10c12-CLA.

• Biomolecules & Therapeutics
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• 제23권2호
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• pp.134-140
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• 2015

Conjugated linoleic acids (CLA) are a family of isomers of linoleic acid. CLA increases growth arrest and apoptosis of human colorectal cancer cells through an isomer-specific manner. ATF3 belongs to the ATF/CREB family of transcription factors and is associated with apoptosis in colorectal cancer. The present study was performed to investigate the molecular mechanism by which t10, c12-CLA stimulates ATF3 expression and apoptosis in human colorectal cancer cells. t10, c12-CLA increased an apoptosis in human colorectal cancer cells in dose dependent manner. t10, c12-CLA induced ATF3 mRNA and luciferase activity of ATF3 promoter in a dose-dependent manner. The responsible region for ATF3 transcriptional activation by t10, c12-CLA is located between -147 and -1850 of ATF3 promoter. mRNA stability of ATF3 was not affected by t10, c12-CLA treatment. t10, c12-CLA increases $GSK3{\beta}$ expression and suppresses IGF-1-stimulated phosphorylation of Akt. The knockdown of ATF3 suppressed expression of $GSK3{\beta}$ and NAG-1 and PARP cleavage. The results suggest that t10, c12-CLA induces apoptosis through ATF3-mediated pathway in human colorectal cancer cells.

• Asian-Australasian Journal of Animal Sciences
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• 제25권1호
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• pp.75-85
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• 2012

An experiment was conducted to compare the effect of the same amount of 18:2 offered either as 18:2n-6 or as a mixture of unprotected 18:2c9t11 and 18:2t10c12 on feed intake, milk components as well as plasma and milk fatty acid profile. Fifteen cows were blocked by milk yield and milk fat percentage and within block assigned randomly to 1 of 3 treatments (n = 5). Each cow passed a 12-d adjustment period (AP) on a basal diet. After the AP cows received 1 of 3 supplements during an 18-d experimental period (EP). The supplements contained either 1.0 kg ground sunflower seeds (S), 0.5 kg conjugated linoleic acid (CLA)-oil (C) or 0.75 kg of a mixture of ground sunflower seeds and CLA-oil (2:1; SC). All 3 supplements contained the same amount of 18:2 either as CLA (${\Sigma}18$:2c9t11+18:2t10c12, 1:1) or as 18:2c9c12. During the last 2 d of AP and the last 4 d of EP feed intake and milk yield were recorded daily and milk samples were collected at each milking. Blood samples were collected from the jugular vein on d 11 of AP and d 15 and 18 of EP. The 18:2 intake increased in all treatments from AP to EP. Regardless of the amount of supplemented CLA, the milk fat percentage decreased by 2.35 and 2.10%-units in treatment C and SC, respectively, whereas in the treatment S the decrease was with 0.99%-unit less pronounced. Thus, C and SC cows excreted daily a lower amount of milk fat than S cows. The concentration of trans 18:1 in the plasma and the milk increased from AP to EP and increased with increasing dietary CLA supply. While the concentration of 18:2c9t11 and 18:2t10c12 in the plasma and that of 18:2t10c12 in the milk paralleled dietary supply, the level of 18:2c9t11 in the milk was similar in C and CS but still lower in S. Although the dietary concentration of CLA was highest in treatment C, the partial replacement of CLA by sunflower seeds had a similar inhibitory effect on milk fat synthesis. Comparable 18:2c9t11 levels in the milk in both CLA treatments implies that this isomer is subjected to greater biohydrogenation with increasing supply than 18:2t10c12. The fact that unprotected 18:2t10c12 escaped biohydrogenation in sufficient amounts to affect milk fat synthesis reveals opportunities to develop feeding strategies where reduced milk fat production is desirable or required by the metabolic state of the cow.

• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1569-1576
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• 2013

In mice, supplementation of t10,c12 conjugated linoleic acid (CLA) increases liver mass and hepatic steatosis via increasing uptake of fatty acids released from adipose tissues. However, the effects of t10,c12 CLA on hepatic lipid synthesis and the associated mechanisms are largely unknown. Thus, we tested the hypothesis that gut microbiota-producing t10,c12 CLA would induce de novo lipogenesis and triglyceride (TG) synthesis in HepG2 cells, promoting lipid accumulation. It was found that treatment with t10,c12 CLA ($100{\mu}M$) for 72 h increased neutral lipid accumulation via enhanced incorporation of acetate, palmitate, oleate, and 2-deoxyglucose into TG. Furthermore, treatment with t10,c12 CLA led to increased mRNA expression and protein levels of lipogenic genes including SREBP1, ACC1, FASN, ELOVL6, GPAT1, and DGAT1, presenting potential mechanisms by which CLA may increase lipid deposition. Most strikingly, t10,c12 CLA treatment for 3 h increased phosphorylation of mTOR, S6K, and S6. Taken together, gut microbiota-producing t10,c12 CLA activates hepatic de novo lipogenesis and TG synthesis through activation of the mTOR/SREBP1 pathway, with consequent lipid accumulation in HepG2 cells.

• Asian-Australasian Journal of Animal Sciences
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• 제20권6호
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• pp.954-961
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• 2007

The experiments were conducted to determine effects of a mixture of conjugated linoleic acid (CLA) isomers on T cell subpopulations and responsiveness to mitogen of splenocytes in male broiler chicks. In experiment 1, birds (8-d old) were fed basal, CLA-(CLA) and safflower oil-supplemented (SA) diets which were formulated by supplementary 10 g CLA or safflower oil/kg to the basal diet for 14 d. Broiler starter diet, which mainly consisted of corn and soybean meal, was served as the basal diet. Proliferative response and interleukin (IL)-2-like activity stimulated by concanavalin (Con) A at a concentration of $10{\mu}g/ml$ of splenocytes in chicks fed the CLA diet were greater than in chicks fed the SA diet, but not at $20{\mu}g$ Con A/ml. Percentage of CD3-positive T cells in splenocytes did not differ between chicks fed the SA diet and CLA. Ratio of CD4-positive T cells to CD8- positive T cells was significantly affected by dietary fat source. In experiment 2, broiler chicks (1-d old) were fed the same diets as in experiment 1 for 14 d. Results of splenocyte proliferation to Con A were similar to those in experiment 1, but phytohemaggulutinin (PHA)- or pokeweed mitogen (PWM)- induced splenocyte proliferation did not differ between the CLA and SA fed groups. Supplementation with SA or CLA to the basal diet tended to have a depressive effect on the proliferation, with the greater effect being that of SA. In experiment 3, effect of an addition of CLA to splenocyte culture medium on splenocyte proliferation was determined. An addition of CLA to the culture medium resulted in reduction of the splenocyte proliferation to Con A, but an addition of linoleic acid. When PWM and PHA were used as mitogen, the inhibitory effect of CLA and linoleic acid on the proliferation did not differ. The results suggested that the effect of dietary CLA on splenocyte proliferation was similar to that of SA, although the effect of dietary CLA on sub-populations was slightly different from that of dietary SA. Further studies are needed to clarify whether use of CLA would be beneficial for maintaining or enhancing T cell immunity in chicks.

• 한국식품영양과학회지
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• 제31권6호
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• pp.1126-1133
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• 2002

CLA 이성체 mixture와 trans-10,cis-12 CLA는 살아있는 TSU-Prl 세포 수를 감소시키는 반면 LA와 cis-9,trans-11 CLA는 세포 수에 아무런 효과가 없었다. 세포 수를 감소시키는 CLA 이성체 mixture와 tran-10, cis-12 CLA는 apoptotic cell death를 유도하는 것을 관찰하였고, 특히 trans-10,cis-12 CLA는 Bcl-2/Bax 비율을 감소시켰다. Trans-10,cis-12 CLA에 의해 Bax와 Bcl-2 mRNA의 수준이 변하지 않았으므로 이 지방산에 의한 Bcl-2의 변화는 mRNA 전사 후에 일어나는 단계에서 일어난다고 결론지을 수 있다. 이로써 CLA에 의한 세포증식 억제는 부분적으로 TSU-Prl 세포의 apoptosis를 유도함으로서 이루어지는 것이라 할 수 있다.

• Journal of Nutrition and Health
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• 제34권8호
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• pp.896-904
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• 2001

Conjugated linoleic acid(CLA) is a group of positional and geometric isomers of linoleic acid(LA) and exhibits anticarcinogenic activity in multiple experimental animal models. Cis-9,trns-11(c9t11) and trans-10,cis-12(t10c12) CLA are the principal isomers found in foods. The present study was performed to determine whether CLA and the two isomers inhibits HT-29 cell proliferation and to assess whether such an effect was related to changes in secretion of eicosanoids. Cells were incubated in serum-free medium with various concentrations(0 to 20$\mu$M) of CLA or LA. CLA inhibited cell proliferation in a dose-dependent manner, with maximal inhibition(70 $\pm$ 1%) observed at 20$\mu$M concentration after 96 hours. However, LA had no effect at the same concentration range. To compare the ability of c9f11 and t10c12 to inhibit cell proliferation, cells were incubated with increasing concentrations(0 to 4$\mu$M) of these isomers. T10c12 inhibited cell proliferation in a dose-dependent manner. A 66 $\pm$ 2% decrease in cell number was observed within 96 hours after addition of 4$\mu$M t10c12. By contrast, c9t11 had no effect. The concentrations of CLA and the two isomers in the plasma membrane were increased when they were added to the incubation medium. However, they did not alter the levels of arachidonic acid in plasma membrane. To assess whether the proliferation inhibiting effect of CLA was related to changes in eicosanoid production, prostaglandin E$_2$(PGE$_2$) and leukotriene B$_4$(LTB$_4$) concentrations in conditioned media were estimated by a competitive enzyme immunoassay. Both CLA and t10c12 increased the production of materials reactive to PGE$_2$ and LTB$_4$ antibodies in a dose-dependent manner. By contrast, c9t11 had no effect. These results indicate that inhibition of HT-29 cell proliferation by CLA is attributed to the effect of the t10v12 isomer. The materials reactive to PGE$_2$ and LTB$_4$ antibodies may inhibit growth stimulatory effect of arachidonic acid-derived eicosanoids on HT-29 cell proliferation.