Research conducted for this dissertation had three goals; 1) determine if CLA can induce milk fat depression immediately postpartum, 2) determine if CLA can alter energy availability, 3) determine the mechanism behind the mammary gland's decreased sensitivity to CLA immediately postpartum. The first study provides strong evidence indicating CLA can decrease milk fat synthesis immediately postpartum, but the dose required is approximately 3x greater than in established lactation. This trial also provided evidence that CLA can alter energy status, as CLA decreased days to EBAL nadir by nearly 5 days. This is relevant as recovery of EBAL from its lowest point provides an important signal for initiating ovarian activity and days to nadir is highly correlated with days to first ovulation. Study two was designed to determine if CLA induced milk fat depression could improve energy status during heat stress. Rumen-inert CLA reduced milk fat synthesis, and was able to improve energy availability, but did not increase milk yield or yield of other milk components. Although production was unchanged in this study, the study did provide further evidence that rumen-inert CLA can alter energy availability. Study three utilized intravenous infusion of CLA in cows in mid and early lactation to determine the mechanism for the mammary gland's decreased sensitivity in early lactation. It is postulated that increased fatty acid oxidation and subsequent enhanced levels of circulating NEFA present during the transition period competitively prevent adequate CLA uptake by the mammary gland. In the current study, trans-10, cis-12 CLA concentration in milk was not different between early and established lactation, while milk fat yield was drastically reduced on d 4 and 5 of trans-10, cis-12 CLA infusion in mid lactation cows, but unaltered in early lactation. Further, NEFA levels were nearly 3 fold higher in early lactation than in mid lactation, providing further evidence that increased circulating NEFAs in early lactation are unlikely to be the source of the mammary gland's decreased sensitivity during this time. Do to the variation in gene expression observed in this trial, we were unable to make any definitive conclusions as to the sensitivity of the expression of genes involved in milk lipid synthesis to CLA in early vs. mid lactation.

Diabetic cardiomyopathy is defined as changes in the structure and function of the myocardium that occur in diabetic patients in the absence of other cardiovascular risk factors. Our laboratory has shown that conjugated linoleic acid (CLA - a naturally-occurring polyunsaturated fatty acid with multiple health benefits) prevents endothelin-1-induced myocyte hypertrophy in vitro, as well as cardiac hypertrophy in vivo using a rodent model of spontaneously hypertensive heart failure. These cardioprotective effects of CLA were mediated through activation of peroxisome proliferator activated receptors (PPAR isomers α and γ) and stimulation of diacylglycerol kinase ζ (DGKζ). Thus, the aims of this study were to (i) determine the effect of CLA on hyperglycemia-induced structural and functional abnormalities of cardiomyocytes, and (ii) assess the role of PPAR-γ and DGK. High glucose treatment induced hypertrophy of primary adult cardiomyocytes, as indicated by augmented cell size and protein synthesis compared to untreated cardiomyocytes. The hyperglycemia-induced hypertrophy was attenuated by pretreatment with CLA (30 µM). The ability of CLA to prevent hyperglycemia-induced hypertrophy was suppressed by GW9662 (1 µM) and R59022 (10 μM), pharmacological inhibitors of PPAR-γ and DGK, respectively. In addition to structural abnormalities, high glucose impaired contractile function of adult cardiomyocytes as measured by maximal velocity of shortening, maximal velocity of relengthening, and peak shortening. Hyperglycemia-induced contractile dysfunction was likewise prevented by pretreatment with CLA (30 µM). Collectively, these findings support the idea that hyperglycemia is an independent risk factor for the development of diabetic cardiomyopathy. Hypertrophy and contractile dysfunction elicited by high glucose were prevented by CLA. The antihypertrophic actions of CLA are mediated, at least in part, by activation of PPAR-γ and DGK.

Enlargement of adipocytes in obesity leads to alteration in adipokine production and these changes are linked to the development of obesity-related cardiovascular diseases. Adipokines specifically associated with obesity-related hypertension include angiotensinogen and adiponectin. Conjugated linoleic acid (CLA) has been reported to reduce blood pressure in obese insulin-resistant rats, but its mechanism of action has not been identified. The objective of this study was to determine whether CLA’s ability to improve obesity-related hypertension involves reducing adipocyte size and altering adipokine production. Fa/fa Zucker rats (6 or 16 week old) were fed diets containing CLA isomers for 8 weeks. The trans(t)10,cis(c)12-CLA isomer reduced adipocyte size in both younger and older rats. Despite beneficial changes in cell size of rats fed the t10,c12-CLA isomer, there were no changes in the renin-angiotensin system or pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 or the anti-inflammatory cytokine IL-10. In contrast, the t10,c12-CLA isomer increased adiponectin levels both in the circulation and in adipose tissue. This was associated with increased phosphorylation of endothelial nitric oxide synthase (eNOS) in adipose tissue and aorta. Direct treatment of CLA isomers in cultured endothelial cells did not increase eNOS phosphorylation but increases were observed with adiponectin treatment. In vivo, infusion with adiponectin increased eNOS phosphorylation in adipose of fa/fa Zucker rats in parallel with improvements in blood pressure. Similarly, when circulating levels of adiponectin increased in rats fed the t10,c12-CLA isomer diet, blood pressure was also attenuated. In younger rats, both the t10-c12 and c9,t11-CLA isomers were significantly different from the control group at week 8, however, only the t10,c12-CLA isomer was comparable to the commonly used anti-hypertensive medication captopril. In conclusion, the beneficial effects of the t10,c12-CLA isomer on blood pressure may in part be due to its ability to reduce the number of large adipocytes in vivo, thus increasing the production of adiponectin which subsequently activates vascular eNOS.

Diabetic cardiomyopathy is defined as changes in the structure and function of the myocardium that occur in diabetic patients in the absence of other cardiovascular risk factors. Our laboratory has shown that conjugated linoleic acid (CLA - a naturally-occurring polyunsaturated fatty acid with multiple health benefits) prevents endothelin-1-induced myocyte hypertrophy in vitro, as well as cardiac hypertrophy in vivo using a rodent model of spontaneously hypertensive heart failure. These cardioprotective effects of CLA were mediated through activation of peroxisome proliferator activated receptors (PPAR isomers α and γ) and stimulation of diacylglycerol kinase ζ (DGKζ). Thus, the aims of this study were to (i) determine the effect of CLA on hyperglycemia-induced structural and functional abnormalities of cardiomyocytes, and (ii) assess the role of PPAR-γ and DGK. High glucose treatment induced hypertrophy of primary adult cardiomyocytes, as indicated by augmented cell size and protein synthesis compared to untreated cardiomyocytes. The hyperglycemia-induced hypertrophy was attenuated by pretreatment with CLA (30 µM). The ability of CLA to prevent hyperglycemia-induced hypertrophy was suppressed by GW9662 (1 µM) and R59022 (10 μM), pharmacological inhibitors of PPAR-γ and DGK, respectively. In addition to structural abnormalities, high glucose impaired contractile function of adult cardiomyocytes as measured by maximal velocity of shortening, maximal velocity of relengthening, and peak shortening. Hyperglycemia-induced contractile dysfunction was likewise prevented by pretreatment with CLA (30 µM). Collectively, these findings support the idea that hyperglycemia is an independent risk factor for the development of diabetic cardiomyopathy. Hypertrophy and contractile dysfunction elicited by high glucose were prevented by CLA. The antihypertrophic actions of CLA are mediated, at least in part, by activation of PPAR-γ and DGK.

Enlargement of adipocytes in obesity leads to alteration in adipokine production and these changes are linked to the development of obesity-related cardiovascular diseases. Adipokines specifically associated with obesity-related hypertension include angiotensinogen and adiponectin. Conjugated linoleic acid (CLA) has been reported to reduce blood pressure in obese insulin-resistant rats, but its mechanism of action has not been identified. The objective of this study was to determine whether CLA’s ability to improve obesity-related hypertension involves reducing adipocyte size and altering adipokine production. Fa/fa Zucker rats (6 or 16 week old) were fed diets containing CLA isomers for 8 weeks. The trans(t)10,cis(c)12-CLA isomer reduced adipocyte size in both younger and older rats. Despite beneficial changes in cell size of rats fed the t10,c12-CLA isomer, there were no changes in the renin-angiotensin system or pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 or the anti-inflammatory cytokine IL-10. In contrast, the t10,c12-CLA isomer increased adiponectin levels both in the circulation and in adipose tissue. This was associated with increased phosphorylation of endothelial nitric oxide synthase (eNOS) in adipose tissue and aorta. Direct treatment of CLA isomers in cultured endothelial cells did not increase eNOS phosphorylation but increases were observed with adiponectin treatment. In vivo, infusion with adiponectin increased eNOS phosphorylation in adipose of fa/fa Zucker rats in parallel with improvements in blood pressure. Similarly, when circulating levels of adiponectin increased in rats fed the t10,c12-CLA isomer diet, blood pressure was also attenuated. In younger rats, both the t10-c12 and c9,t11-CLA isomers were significantly different from the control group at week 8, however, only the t10,c12-CLA isomer was comparable to the commonly used anti-hypertensive medication captopril. In conclusion, the beneficial effects of the t10,c12-CLA isomer on blood pressure may in part be due to its ability to reduce the number of large adipocytes in vivo, thus increasing the production of adiponectin which subsequently activates vascular eNOS.

Thesis (MScAgric)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vii, 45 p. : ill. Includes abstract. Includes bibliographical references (p. 37-45).

Thesis (Ph. D.)--University of North Carolina at Greensboro, 2006. / Title from PDF title page screen. Advisor: Michael K. McIntosh; submitted to the School of Health and Human Performance. Includes bibliographical references (p. 133-151).

The potential for conjugated linoleic acid (CLA) incorporation into pressure-sensitive adhesive (PSA) formulations was evaluated. A series of free radical bulk copolymerizations of CLA/styrene (Sty) and CLA/butyl acrylate (BA) were designed to allow the estimation of reactivity ratios. Bulk terpolymerizations of CLA/Sty/BA were also evaluated before moving to emulsion terpolymerizations of CLA/Sty/BA. The polymers were characterized for composition, conversion, molecular weight and glass transition temperature while latexes were characterized for viscosity, particle size, tack, peel strength, and shear strength. All experiments were performed at 80oC and monitored with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. While bulk experiments were monitored off-line, the emulsion experiments were monitored in-line. Absorbance peaks related to the monomers and polymer were tracked to provide conversion and polymer composition data using a multivariate calibration method. Off-line measurements using gravimetry and 1H-NMR spectroscopy were compared to the ATR-FTIR data and no significant differences were detected between the measurement methods. Pseudo-kinetic models, developed and validated with the copolymer experimental data, were used to estimate reactivity ratios. The copolymer pseudo-kinetic models were extended to a terpolymer pseudo-kinetic model and validated with experimental data. The pseudo-kinetic models incorporated the ability of oleic acid, a common impurity found in CLA, to trap electrons thus influencing the reaction kinetics significantly. The influence of terpolymer composition, chain transfer agent concentration, cross-linker concentration, molecular weight, viscosity and particle size on tack, peel strength and shear strength was investigated by using a constrained mixture design. The final forms of the resulting empirical models allowed the creation of 3D response surfaces for PSA performance optimization. The incorporation of 30 wt.% CLA into a practical PSA application suitable for the removable adhesives category was achieved.

Approximately 200 million people worldwide, including 25 million in the United States, suffer from osteoporosis. The pathophysiology of osteoporosis suggests that prevention through dietary intervention can be one of the most important actions. Diet can also be a successful alternative for minimizing bone loss and the need for osteoporosis related drug therapy. Conjugated linoleic acid (CLA) is the collective term used to describe positional and geometric isomers of linoleic acid with two conjugated double bonds. CLA has been shown to be biologically active in many systems, yet CLA’s effect on bone mass is not clearly established. The purpose of this research is to investigate CLA’s isomeric effect and synergy with dietary calcium on bone mass. CLA was observed to increase the body ash, representative of bone mass, in male ICR mice after 4-weeks of supplementation. CLA was also administered to mouse bone marrow mesenchymal stem cells during osteoblastic differentiation. CLA increased protein expression related to osteogenesis as well as increasing the calcium concentration of the osteoblastic matrix. In summary, this research provides evidence for the ability of CLA to preserve bone mass.