• Food Science and Biotechnology
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• v.18 no.3
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• pp.586-593
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• 2009

Since conjugated linoleic acid (CLA) was identified as a principal anticancer component from ground beef in the 1980s, CLA research has discovered that CLA has a wide range of biologically beneficial effects. Clinical studies with CLA are on the rise, and it is apparent that CLA may not be as effective in humans as in rodents, in particular its anti-obesity aspect. In addition, research with regard to other conjugated fatty acids as well as CLA metabolites is still in its infancy. Investigation of bioactivities for other conjugated fatty acids and CLA metabolites may help to extend the understanding of CLA and its mechanisms of actions. This may pose an opportunity to use CLA more efficiently and expand the future use of other conjugated fatty acids as pharmacological agents to assist current treatments.

• Journal of Nutrition and Health
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• v.30 no.4
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• pp.442-450
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• 1997

Conjugated dienoic derivatives of linoleic acid(CLA) are a mixture of positional and geometric isomers of linoleic acid(LA). We previously found that CLA changes the fatty acid profile in chicken eggs and serum by decreasing monounsaturated fatty acids. Studies were conducted to explore the effects of CLA on fatty acid composition. Rabbits were fed a semisynthetic diet with or without CLA(0.5g CLA/rabbit/day) for 22 weeks. Compared to the control, rabbits fed CLA had significantly lower monounsaturated fatty acid levels(palmitoleic acid Cl6 : 1 by 50% and oleic acid Cl8 : 1, by 20%) in plasma lipids. We found similar differences in fatty acid composition in the liver and the aorta. The inhibitory effect of CLA on $\Delta$9 desaturation was confirmed in a human hepatoma cell line, Hep G2. CLA significantly decreased $\Delta$9 desaturation in 4-5 hours as shown by an increase in the ratio of Cl6 : 0 to C 16 1, This is apparently due to a decrease in $\Delta$9 desaturase(stearoyl-CoA desaturase, SCD) activity ; it was decreased more than 50%. These results, along with our previous findings, indicate that CLA is an inhibitor of $\Delta$9 desaturase in the liver.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1617-1619
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• 2009

Lactobacillus rhamnosus PL60 was tested for whether it can produce c9,t11- and t10,c12-conjugated linoleic acids (CLAs) in human. After consumption of L. rhamnosus PL60, L. rhamnosus was detected in feces 1 week after the start of intake. Analysis by gas chromatography showed that concentrations of c9,t11- and t10,c12-CLAs in serum had increased and concentrations of serum leptin had significantly decreased. Results showed that L. rhamnosus PL60 can survive in human intestines and produce CLAs in humans. This is the first report that bacteria can produce CLAs in humans.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.9
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• pp.1271-1277
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• 2008

The effects of feeding soybean oil (SBO) or rumen protected conjugated linoleic acid (RP-CLA) on CLA accumulation in milk, and performance of lactating dairy cows were studied. Twenty four Holstein Friesian crossbred lactating dairy cows, averaging $126{\pm}45days$ in milk, $15.6{\pm}2.43kg$ of milk and $452{\pm}51kg$ body weight were stratified randomly and assigned in a randomized complete block design (RCBD) to three treatments of 8 cows each. The treatments were control, 150 g of SBO and 150 g of RP-CLA supplementation. Performance parameters showed that DM intake, NELP intake and body weight change were similar across treatments, while CP intake was decreased by SBO and RP-CLA supplementation. Milk yield and milk composition were not significantly different among treatments, except for milk fat percentage and fat yield which were significantly decreased by 27% (p<0.05) and by 28% (p<0.01), respectively, by RP-CLA supplements compared with control treatment. Feeding RP-CLA reduced 3.5% FCM compared with the other treatments (p<0.003). Both SBO and RP-CLA supplementation reduced ${\geq}C18:0$ and CLA concentration in milk fat.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.22-28
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• 2003

Increasing conjugated linoleic acid (CLA) content in dairy products has been a research Interest due to the potential health benefits resulted from consuming CLA. Attempts were made to obtain high level natural CLA containing fatty acid fractions from milk fat through bovine feeding of sunflower oil (SO) and urea fractionation. SO feeding changed the fatty acid profile of milk fat. increasing the CLA content five-fold at eight weeks of trial. Milk fat obtained from S0-fed cows was hydrolyzed to free fatty acids, which were then fractionated with urea at various ratios. The profiles of fatty acids were also greatly influenced by urea fractionation. Long-chain unsaturated fatty acids, Including CLA, were concentrated in milk fat after the fractionation, whereas saturated long-chain counterparts were eliminated. The highest level of CLA was achieved by the fractionation at 2:1 urea/fatty acid ratio (UFR2). CLA level was elevated 2.5-fold, and the Cl8:1/C18:0 fatty acid ratio was increased 120 times after the fractionation. The level of CLA in high CLA-milk fat (24mg/g fat) obtained from the feeding study was further increased through urea fractionation up to 52mg/g fat, 10 folds as high as CLA in the control milk fat (5mg/g fat).

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.306-314
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• 2003

Bio-hydrogenation of $C_{18}$-unsaturated fatty acids released from the hydrolysis of dietary lipids in the rumen, in general, occurs rapidly but the range of hydrogenation is quite large, depending on the degree of unsaturation of fatty acids, the configuration of unsaturated fatty acids, microbial type and the experimental condition. Conjugated linoleic acid (CLA) is incompletely hydrogenated products by rumen microorganisms in ruminant animals. It has been shown to have numerous potential benefits for human health and the richest dietary sources of CLA are bovine milk and milk products. The cis-9, trans-11 is the predominant CLA isomer in bovine products and other isomers can be formed with double bonds in positions 8/10, 10/12, or 11/13. The term CLA refers to this whole group of 18 carbon conjugated fatty acids. Alpha-linolenic acid goes through a similar bio-hydrogenation process producing trans-11 $C_{18:1}$ and $C_{18:0}$, but may not appear to produce CLA as an intermediate. Although the CLA has been mostly derived from the dietary $C_{18:2}$ alternative pathway may be existed due to the extreme microbial diversity in the reticulo-rumen. Regardless of the origin of CLA, manipulation of the bio-hydrogenation process remains the key to increasing CLA in milk and beef by dietary means, by increasing rumen production of CLA. Although the effect of oil supplementation on changes in fatty acid composition in milk seems to be clear its effect on beef is still controversial. Thus further studies are required to enrich the CLA in beef under various dietary and feeding conditions.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1243-1246
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• 1998

The contents of conjugated linoleic acid (CLA) of 36 commercial dairy products (15 fluid milks, 16 yogurts, 5 cheeses) were determined. The CLA contents of fluid milk and cheeses were in the range of 2.24 to 4.10 mg/g and 3.69 to 5.78 mg/g of lipid, respectively. However, the yogurt products showed a large variation ($0.13{\sim}4.54\;mg/g$ of lipid) of CLA content because the yogurts prepared from skim milk contained lower CLA than those prepared from whole milk. Multiple linear regression test showed good correlations between CLA contents and the contents of selected fatty acids (oleic, linoleic and linolenic acids) of fluid milk and yogurt products.

• Journal of Nutrition and Health
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• v.35 no.10
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• pp.1038-1044
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• 2002

The study was designed to observe the effect of conjugated linoleic acid (CLA) on tumor incidence, eicosanoid formation and antioxidant enzyme activities in colonic mucosa and the fecal excretion of deoxycholic acid and lithocholic acid in 1,2-dimethylhydrazine (DMH)-treated rats. One hundred twenty male Sprague Dawley rats were divided into 2 groups, BT (beef tallow diet) group and FO (fish oil diet) group, and each group was again subdivided into 2 groups depending on CLA supplementation, i.e.4 groups of BT, BTC, FO, FOC. All rats were fed experimental diet for 30 weeks, which contained 12% (wt/wt) total dietary fat including 1% (wt/wt) CLA, and were intramuscularly injected with DMH for 6 weeks to give total dose of 180 mg/kg body. CLA-supplemented to BT and FO diet reduced tumor incidence, eicosanoid (PGE$_2$ and TXA$_2$) level in colonic mucosa. N-3 fatty acids (mainly DHA) of fish oil diet (FO, FOC group) also reduced tumor incidence and significantly reduced eicosanoid (PGE$_2$ and TXA$_2$) level in colonic mucosa. CLA supplementation and n-3 fatty acid significantly increased colonic mucosal level of superoxide dismutase and glutathione peroxidase activities but reduced secondary bile acids (deoxycholic acid and lithocholic acid) excretion in the feces. In conclusion, CLA supplementation and n-3 fatty acid could reduce tumor incidence by reducing eicosanoids and increasing antioxidant enzyme activities in colon and decreasing the excretion of deoxycholic acid and lithocholic acid in the feces. The data might suggest that CLA supplementation and n-3 DHA rich fish oil may modulate colon carcinogenesis.termediate level of endurance exercise training for 6 weeks did not influence concentrations of most of free amino acid in soleus muscle of rats collected at an overnight fasted and rested state. In contrast, isolucine and leucine concentrations in extensor digitorum longus muscle of exercise-trained rats were significantly lower than those for control animals. These results indicate that aerobic energy metabolism had not been efficiently conducted, and thereby the utilization of BCAA for energy substrate was enhanced in fast twitch oxidative glycolytic fibers of extensor digitorum longus muscle of rats followed exercise-training protocol for 6 weeks.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.11
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• pp.1694-1698
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• 2007

The objective of this study was to identify biohydrogenation pathways for linoleic, linolenic, oleic and stearic acids by Orpinomyces species of rumen fungus during in vitro culture. Biohydrogenation of linoleic acid produced conjugated linoleic acid (cis-9, trans-11 C18:2), which was then converted to vaccenic acid (trans-11 C18:1) as the end product of biohydrogenation. Biohydrogenation of linolenic acid produced cis-9, trans-11, cis-15 C18:3 and trans-11, cis-15 C18:2 as intermediates and vaccenic acid as the end product of biohydrogenation. Oleic acid and stearic acid were not converted to any other fatty acid. It is concluded that pathways for biohydrogenation of linoleic and linolenic acids by Orpinomyces are the same as those for group A rumen bacteria.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.203-208
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• 1999

The effect of the polyunsaterated fatty acids, linoleic acid(LA), arachidonic acid(AA) and conjugated dienoic linoleic acid(CLA) on IEC-6 cells (rat intestinal cell)proliferation and cell transduction have been determined in vitro. IEC-6 cells proliferation was assessed by cell growth and [3H]-thymidine incroporation analysis. At 10 μM concentration , the proliferationof cells supplemented with AA or LA was significantly higher than that of CLA. [3H]-thymidine uptake showed the same results. LA and AA increased [3H]-thymidine uptake more than CLA. The stimulatory effect of LA or AA was even more pronounced in the presence of IGF. Both cell number analysis and [3H]-thymidine incorporation revealed that IEC-6 cell proliferation was influenced differently by exogenous free fatty acids, in which AA or LA stimulated IEC-6 cell proliferation and CLA inhibited it. Tyorosine phosphorylation provides a key switch to regulate celluar acitivity in response to extracellular stimuli. At 20 μM and 10μM, AA with IGF-1 stimulated protein tyrosine phophorylation in IEC-6 cells, but LA's impact was less than that of AA. CLA and CLA with IGF-1 inhibited protein tyrosine phosphorylation in IEC-6 cells. These results suggest there is a possible correlation between cell proliferation and IGF receptor tyrosine knase activity driven by AA.