A nanoemulsion formulation of dacarbazine reduces tumor size in a xenograft mouse epidermoid carcinoma model compared to dacarbazine suspension.

Dacarbazine (DAC) is an anticancer drug that has been used to treat various types of cancers. The aim of the current study was to test whether there is an increased efficacy of DAC as a nanoemulsion on reducing tumor size in an epidermoid carcinoma xenograft mouse model. Tumors were induced in 5-week-old nude mice by subcutaneous injection. The mice were untreated or treated with a suspension of DAC (0.1 mg/kg), a nanoemulsion of DAC (0.1 mg/kg), or Nano-Control (same composition as the suspension and nanoemulsion but no DAC), every 2 days by either intramuscular injection (IM) or topical application. After 40 days, the final tumor size of mice receiving the nanoemulsion of DAC IM (0.83 ± 0.55 mm(3)) was significantly reduced compared to the suspension of DAC IM (4.75 ± 0.49 mm(3)), Nano-Control IM (7.63 ± 0.91 mm(3)), and untreated (10.46 ± 0.06 mm(3)). The final tumor size of mice receiving the nanoemulsion of DAC topically (3.33 ± 0.63 mm3) was also significantly reduced compared to the suspension of DAC topically (7.64 ± 0.68 mm(3)). This increased efficacy maybe partially attributed to: 1) the reduced particle size of the nanoemulsion in comparison with suspension (111 versus > 6000 nm), 2) reduction in zeta potential of the nanoemulsion compared to suspension (-3.2 versus -89.1 mV), 3) production of a stable water dispersion relative to unstable suspension, 4) decreased polydispersity index of the nanoemulsion compared to suspension, and 5) greater stability of drug with the nanoemulsion in comparison with the suspension. FROM THE CLINICAL EDITOR: In this clinically relevant study, the anti-tumor efficacy of dacarbazine was found to be significantly increased as a nanoemulsion in epidermoid carcinoma xenograft mice, both with IM and topical administration.

Encapsulation of cadmium selenide quantum dots using a self-assembling nanoemulsion (SANE) reduces their in vitro toxicity.

Although, nanometer-scale semi-conductor quantum dots (QDs) have attracted widespread interest in medical diagnosis and treatment, many can have intrinsic toxicities, especially those composed of CdSe, associated with their elemental composition. Using our self-assembling nanoemulsion (SANE) formulations which we have previously reported to be composed of non-toxic components, i.e., such as vegetable oil, surfactant and water, we hypothesized that their appropriate utilization would reduce the toxicity of QDs by encapsulating the CdSe QDs in our (SANE) system using a modified phase-inversion temperature (PIT) method. SANE encapsulation of the QDs did not alter their emission wavelength of 600nm which remained unchanged during the encapsulation process. In contrast, zeta potential of encapsulated QDs was reduced from -30 to -6.59 mV, which we have previously reported to be associated with beneficial properties (increased bioavailability and efficacy) for SANE-encapsulated bioactives such as pharmaceuticals. Relative to the untreated controls, the viability of HeLa cells exposed for 48 h to un-encapsulated CdSe QDs at a concentration of 115 µg/mL was 22.7±1.7% (p<0.05). In contrast, the percentage of viable HeLa cells following exposure to SANE-encapsulated CdSe QDs at the same concentration was 91.6±3.5% (p<0.05) or a 307% increase in the number of viable cells (p<0.05). When the dose of CdSe QDs was increased to 230 µg/mL, the percentage of viable HeLa cells after exposure to the un-encapsulated CdSe QDs was 16.1±1.3% compared to controls (p<0.05). In contrast, at the same increased concentration (230 µg/mL) of un-encapsulated CdSe QDs, the percentage of viable HeLa cells following exposure to SANE-encapsulated CdSe QDs was 87.9±3.3% relative to controls (p<0.05) or a 448% increase in the number of viable cells (p<0.05). Exposure of HeLa cells to a nanoblank, (nanoemulsion without QDs), showed no significant effect on cell viability (97.2±2.5%) compared to control cell culture. In conclusion, application of our SANE technology for encapsulating QDs increased cell viability of cells exposed to CdSe QDs while maintaining the original emission wavelength and therefore may be applied to reduce QD toxicity.

Increased consumption of dietary cholesterol, lutein, and zeaxanthin as egg yolks does not decrease serum concentrations and lipoprotein distribution of other carotenoids, retinol, and tocopherols.

We have previously reported that consumption of lutein and zeaxanthin as 2 and 4 egg yolks per day for 5 weeks significantly increased serum lutein and zeaxanthin concentrations in older adults taking cholesterol-lowering statins. We hypothesized that increased consumption of eggs, lutein, and zeaxanthin may correlate with decreased absorption of other carotenoids and increased absorption of vitamins A and E, thus affecting their serum concentrations and lipoprotein distribution. Fifty-two subjects aged at least 60 years consumed 2 egg yolks per day followed by 4 egg yolks per day for 5 weeks each with a 4-week egg-free period at baseline and between the 2 interventions. Mean serum ß-cryptoxanthin, lycopene, α-carotene, ß-carotene, α-tocopherol, and retinol concentrations did not change during the 2 and 4 egg yolk phases. Mean serum α-cryptoxanthin and γ-tocopherol concentrations did not change after the 2 egg yolk phase, but increased by 47% (P < .001) and 19% (P < .05), respectively, after the 4 egg yolk phase. The percentage distribution of carotenoids and tocopherols between the high-density lipoprotein (HDL) and non-HDL fractions was not significantly different during the egg yolk phases compared with baseline despite the significant increases in lutein and zeaxanthin carried on HDL and non-HDL fractions. In conclusion, increased dietary cholesterol, lutein, and zeaxanthin consumed as egg yolks did not decrease the absorption of other carotenoids, and increased γ-tocopherol but not retinol as evidenced by their serum and lipoprotein concentrations. Two and 4 egg yolk consumption increases serum and retinal lutein and zeaxanthin without altering the serum status of the other carotenoids, tocopherol, and retinol.

Consumption of 2 and 4 egg yolks/d for 5 wk increases macular pigment concentrations in older adults with low macular pigment taking cholesterol-lowering statins.

BACKGROUND: Lutein and zeaxanthin may reduce the risk of dry, age-related macular degeneration because of their photo-oxidative role as macular pigment. OBJECTIVE: The present study evaluated serum lutein, zeaxanthin, and macular pigment optical density (MPOD) responses at 0.25 degrees , 0.5 degrees , and 1 degree retinal eccentricities to the consumption of 2 and 4 egg yolks/d by older adults taking cholesterol-lowering medications. DESIGN: Subjects consumed foods containing 2 followed by 4 egg yolks/d for 5 wk each with a 4-wk egg-free period at baseline and between the 2 interventions. RESULTS: Changes in MPOD (n = 37) with egg yolk consumption were inversely associated (P < 0.05) with baseline MPOD. Subjects with low-baseline MPOD (defined as MPOD < or =0.5 at 0.25 degrees , < or =0.4 at 0.5 degrees , and < or =0.35 at 1 degrees ) showed increases of < or =50% (P < 0.05) with 4 egg yolks at the 3 retinal eccentricities. MPOD increased by 31% (P = 0.059) at 0.5 degrees with 2 egg yolks. Serum lutein increased by only 16% and 24% (P < 0.05) compared with increases of 36% and 82% (P < 0.001) in serum zeaxanthin (n = 52) after consumption of 2 and 4 egg yolks, respectively. Serum HDL cholesterol increased by 5% (P < 0.05) after consumption of 2 and 4 egg yolks. Serum LDL cholesterol did not change with either egg yolk treatment. CONCLUSIONS: Consumption of 4 egg yolks/d, and possibly of 2 egg yolks/d, for 5 wk benefited macular health in older adults with low MPOD. Serum HDL cholesterol increased without an increase in LDL cholesterol in this study population, most of whom were taking cholesterol-lowering statins.

Nanoemulsions of an anti-oxidant synergy formulation containing gamma tocopherol have enhanced bioavailability and anti-inflammatory properties.

The present study investigated whether MicroFluidizer Processor-based nanoemulsions of an antioxidant synergy formulation (ASF), containing delta, alpha and gamma tocopherol influenced inflammation and bioavailability in CD-1 mice. Croton oil was applied to all animals' right ear lobe to induce inflammation. Auricular thickness was measured after 2 and 6h after the various treatments. The animal plasma and ear lobes were collected and frozen for bioavailability and cytokine analyses. The ASF nanoemulsions of alpha, delta, or gamma tocopherol significantly reduced auricular thickness compared to control (57, -57, and -71%, respectively) and blank nanoemulsion (-50, -50, -67%, respectively). Relative to the suspensions of ASF, only the nanoemulsion of ASF containing gamma tocopherol significantly reduced auricular thickness (-60%), whereas the 40% reduction with nanoemulsions of delta tocopherol compared to suspension was not statistically significant. Auricular concentrations of cytokines TNF-alpha and IL-1 alpha were significantly reduced in mice treated only with ASF nanoemulsions of gamma tocopherol compared to control (-53, -46%, respectively) and blank nanoemulsion (-52, -46%, respectively). Auricular thickness was significantly associated with tissue TNF-alpha (r=0.539, p<0.001) and IL-1 alpha concentrations (r=0.404, p=0.01). Bioavailability for gamma and delta was dramatically enhanced (2.2- and 2.4-folds) with the nanoemulsion compared to suspensions. Only the plasma gamma tocopherol concentration was significantly associated with auricular thickness (r=-0.643, P=0.001). In conclusion, nanoemulsions of ASF containing gamma, alpha, and delta tocopherol, have enhanced anti-inflammatory properties and increased bioavailability, with gamma tocopherol, in particular compared to their suspensions.

A nanoemulsion formulation of tamoxifen increases its efficacy in a breast cancer cell line.

This paper reports on the preparation of a water-soluble nanoemulsion of the highly lipid-soluble drug tamoxifen (TAM). In addition, relative to a suspension of TAM, the nanoemulsion preparation demonstrated a greater zeta potential (increased negative charge) which has previously been associated with increasing drug/membrane permeability. This study also reports that relative to suspensions of TAM with particle sizes greater than 6000 nm, nanoemulsions of TAM, having mean particle sizes of 47 nm, inhibited cell proliferation 20-fold greater and increased cell apoptosis 4-fold greater in the HTB-20 breast cancer cell line. Thus, this work suggests that a nanoemulsion compared to a suspension preparation of TAM increases its anticancer properties relative to breast cancer.

Nanoemulsion preparations of the anticancer drug dacarbazine significantly increase its efficacy in a xenograft mouse melanoma model.

This article reports on the preparation of a water-soluble nanoemulsion of the highly lipid-soluble drug Dacarbazine (DAC). In addition, relative to suspensions of DAC, the nanoemulsion preparation demonstrated a lower zeta-potential (decreased negative charge, less anionic and more cationic) which has previously been associated with influencing drug membrane permeability. This study also reports that, relative to suspensions of DAC with a mean particle size of 5470 nm, nanoemulsions of DAC having mean particle sizes of 131 nm were more efficacious. For example, in a mouse xenograft model using a human melanoma cell line, a topical application of nanoemulsions of DAC compared to the suspension preparation of DAC produced up to 10-fold greater percent (%) reductions of tumor size. The reduction in tumor size by the intramuscular (IM) injection (-61%) and topical application of the nanoemulsion preparations of DAC (-49%) appeared to be comparable in efficacy, although the former was statistically greater (p < 0.05). In addition, 12 weeks after DAC treatment cessation, 98% of the animals given the IM application of the nanoemulsion of DAC remained tumor-free compared to the control or untreated animals. During this drug cessation period, and compared to the suspension preparations, nanoemulsions of DAC showed 5-fold greater efficacies (73% versus 14%) in preventing tumor growth. In conclusion, in this xenograft mouse model of melanoma, nanoemulsion suspensions of DAC are more efficacious in the treatment and prevention of tumor growth.

Rice bran oil and oryzanol reduce plasma lipid and lipoprotein cholesterol concentrations and aortic cholesterol ester accumulation to a greater extent than ferulic acid in hypercholesterolemic hamsters.

Our laboratory has reported that the hypolipidemic effect of rice bran oil (RBO) is not entirely explained by its fatty acid composition. Because RBO has a greater content of the unsaponifiables, which also lower cholesterol compared to most vegetable oils, we wanted to know whether oryzanol or ferulic acid, two major unsaponifiables in RBO, has a greater cholesterol-lowering activity. Forty-eight F(1)B Golden Syrian hamsters (Mesocricetus auratus) (BioBreeders, Watertown, MA) were group housed (three per cage) in cages with bedding in an air-conditioned facility maintained on a 12-h light/dark cycle. The hamsters were fed a chow-based hypercholesterolemic diet (HCD) containing 10% coconut oil and 0.1% cholesterol for 2 weeks, at which time they were bled after an overnight fast (16 h) and segregated into 4 groups of 12 with similar plasma cholesterol concentrations. Group 1 (control) continued on the HCD, group 2 was fed the HCD containing 10% RBO in place of coconut oil, group 3 was fed the HCD plus 0.5% ferulic acid and group 4 was fed the HCD plus 0.5% oryzanol for an additional 10 weeks. After 10 weeks on the diets, plasma total cholesterol (TC) and non-high-density lipoprotein cholesterol (HDL-C) (very low- and low-density lipoprotein) concentrations were significantly lower in the RBO (-64% and -70%, respectively), the ferulic acid (-22% and -24%, respectively) and the oryzanol (-70% and -77%, respectively) diets compared to control. Plasma TC and non-HDL-C concentrations were also significantly lower in the RBO (-53% and -61%, respectively) and oryzanol (-61% and -70%, respectively) diets compared to the ferulic acid. Compared to control and ferulic acid, plasma HDL-C concentrations were significantly higher in the RBO (10% and 20%, respectively) and oryzanol (13% and 24%, respectively) diets. The ferulic acid diet had significantly lower plasma HDL-C concentrations compared to the control (-9%). The RBO and oryzanol diets were significantly lower for plasma triglyceride concentrations compared to the control (-53% and -65%, respectively) and ferulic acid (-47% and -60%, respectively) diets. Hamsters fed the control and ferulic acid diets had significantly higher plasma vitamin E concentrations compared to the RBO (201% and 161%, respectively) and oryzanol (548% and 462%, respectively) diets; the ferulic acid and oryzanol diets had significantly lower plasma lipid hydroperoxide levels than the control (-57% and -46%, respectively) diet. The oryzanol-fed hamsters excreted significantly more coprostenol and cholesterol in their feces than the ferulic acid (127% and 120%, respectively) diet. The control diet had significantly greater aortic TC and FC accumulation compared to the RBO (115% and 89%, respectively), ferulic acid (48% and 58%, respectively) and the oryzanol (74% and 70%, respectively) diets. However, only the RBO and oryzanol diets had significantly lower aortic cholesterol ester accumulation compared to the control (-73% and -46%, respectively) diet. The present study suggests that at equal dietary levels, oryzanol has a greater effect on lowering plasma non-HDL-C levels and raising plasma HDL-C than ferulic acid, possibly through a greater extent to increase fecal excretion of cholesterol and its metabolites. However, ferulic acid may have a greater antioxidant capacity via its ability to maintain serum vitamin E levels compared to RBO and oryzanol. Thus, both oryzanol and ferulic acid may exert similar antiatherogenic properties, but through different mechanisms.

Consumption of one egg per day increases serum lutein and zeaxanthin concentrations in older adults without altering serum lipid and lipoprotein cholesterol concentrations.

Lutein and zeaxanthin accumulate in the macular pigment of the retina, and are reported to be associated with a reduced incidence of age-related macular degeneration. A rich source of lutein and zeaxanthin in the American diet is the yolk of chicken eggs. Thus, the objective of the study was to investigate the effect of consuming 1 egg/d for 5 wk on the serum concentrations of lutein, zeaxanthin, lipids, and lipoprotein cholesterol in individuals >60 y of age. In a randomized cross-over design, 33 men and women participated in the 18-wk study, which included one run-in and one washout period of no eggs prior to and between two 5-wk interventions of either consuming 1 egg or egg substitute/d. Serum lutein 26% (P < 0.001) and zeaxanthin 38% (P < 0.001) concentrations increased after 5-wk of 1 egg/d compared with the phase prior to consuming eggs. Serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides were not affected. These findings indicate that in older adults, 5 wk of consuming 1 egg/d significantly increases serum lutein and zeaxanthin concentrations without elevating serum lipids and lipoprotein cholesterol concentrations.

A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women.

Two carotenoids found in egg yolk, lutein and zeaxanthin, accumulate in the macular retina where they may reduce photostress. Increases in serum lutein and zeaxanthin were observed in previous egg interventions, but no study measured macular carotenoids. The objective of this project was to determine whether increased consumption of eggs would increase retinal lutein and zeaxanthin, or macular pigment. Twenty-four females, between 24 and 59 y, were assigned to a pill treatment (PILL) or 1 of 2 egg treatments for 12 wk. Individuals in the PILL treatment consumed 1 sugar-filled capsule/d. Individuals in the egg treatments consumed 6 eggs/wk, containing either 331 microg (EGG 1) or 964 microg (EGG 2) of lutein and zeaxanthin/yolk. Serum cholesterol, serum carotenoids, and macular pigment OD (MPOD) were measured at baseline and after 4, 8, and 12 wk of intervention. Serum cholesterol concentrations did not change in either egg treatment group, but total cholesterol (P = 0.04) and triglycerides (P = 0.02) increased in the PILL group. Serum zeaxanthin, but not serum lutein, increased in both the EGG 1 (P = 0.04) and EGG 2 (P = 0.01) groups. Likewise, MPOD increased in both the EGG 1 (P = 0.001) and EGG 2 (P = 0.049) groups. Although the aggregate concentration of carotenoid in 1 egg yolk may be modest relative to other sources, such as spinach, their bioavailability to the retina appears to be high. Increasing egg consumption to 6 eggs/wk may be an effective method to increase MPOD.

Structured triglycerides containing caprylic (8:0) and oleic (18:1) fatty acids reduce blood cholesterol concentrations and aortic cholesterol accumulation in hamsters.

The effects of structured triglycerides containing one long chain fatty acid (oleic acid, C18:1) and one short chain saturated fatty acid (caprylic acid, 8:0) on lipidemia, liver and aortic cholesterol, and fecal neutral sterol excretion were investigated in male Golden Syrian hamsters fed a hypercholesterolemic regimen consisting of 89.9% commercial ration to which was added 10% coconut oil and 0.1% cholesterol (w/w). After 2 weeks on the HCD diet, the hamsters were bled, following an overnight fast (16 h) and placed into one of three dietary treatments of eight animals each based on similar plasma cholesterol levels. The hamsters either continued on the HCD diet or were placed on diets in which the coconut oil was replaced by one of two structured triglycerides, namely, 1(3),2-dicaproyl-3(1)-oleoylglycerol (OCC) or 1,3-dicaproyl-2-oleoylglycerol (COC) at 10% by weight. Plasma total cholesterol (TC) in hamsters fed the OCC and COC compared to the HCD were reduced 40% and 49%, respectively (P<0.05). Similarly, hamsters fed the OCC and COC diets reduced their plasma nonHDL cholesterol levels by 47% and 57%, respectively (P<0.05), compared to hamsters fed the HCD after 2 weeks of dietary treatment. Although hamsters fed the OCC (-26%) and COC (-32%) had significantly lower plasma HDL levels compared to HCD, (P<0.05), the plasma nonHDL/HDL cholesterol ratio was significantly lower (P<0.05) compared to the HCD for the OCC-fed (-27%) and the COC-fed (-38%) hamsters, respectively. Compared to the HCD group, aortic esterified cholesterol was 20% and 53% lower for the OCC and COC groups, respectively, with the latter reaching statistical significance, P<0.05. In conclusion, the hamsters fed the structured triglyceride oils had lower blood cholesterol levels and lower aortic accumulation of cholesterol compared to the control fed hamsters.

Conjugated linoleic acid isomers reduce blood cholesterol levels but not aortic cholesterol accumulation in hypercholesterolemic hamsters.

The aim of the present study was to characterize plasma lipids and lipoprotein cholesterol and glucose concentrations in hamsters fed either cis-9,trans-11 CLA (9c,11 tCLA); trans-10,cis-12 CLA (10t,12c CLA); or linoleic acid (LA) on the accumulation of aortic cholesterol in hypercholesterolemic hamsters. One hundred male F1B strain Syrian Golden Hamsters (Mesocricetus auratus) (BioBreeders Inc., Watertown, MA) approximately 9 wk of age were housed in individual stainless steel hanging cages at room temperature with a 12-h light/dark cycle. Hamsters were given food and water ad libitum. Following a 1-wk period of acclimation, the hamsters were fed a chow-based (nonpurified) hypercholesterolemic diet (HCD) containing 10% coconut oil (92% saturated fat) and 0.1% cholesterol for 2 wk. After an overnight fast, the hamsters were bled and plasma cholesterol concentrations were measured. The hamsters were then divided into 4 groups of 25 based on similar mean plasma VLDL and LDL cholesterol (nonHDL-C) concentrations. Group 1 remained on the HCD (control). Group 2 was fed the HCD plus 0.5% 9c,11t CLA isomer. Group 3 was fed the HCD plus 0.5% 10t,12c CLA isomer. Group 4 was fed the HCD plus 0.5% LA. Compared with the control, both CLA isomers and LA had significantly lower plasma total cholesterol and HDL cholesterol concentrations (P < 0.001) after 12 but not 8 wk of treatment and were not significantly different from each other. Also, both CLA isomers had significantly lower plasma nonHDL-C concentrations (P < 0.01) compared with the control after 12 but not 8 wk of treatment and were not significantly different from each other or the LA-fed hamsters. Plasma TG concentrations were significantly higher (P < 0.004) with the 10t, 12c CLA isomer compared with the other treatments at 8 but not at 12 wk of treatment. Plasma TG concentrations were also significantly lower (P < 0.03) with the 9c,11t CLA isomer compared with the control at 12 wk of treatment. Also, the 10t,12c CLA isomer and LA had significantly higher plasma glucose concentrations compared with the control and 9c,11t CLA isomer (P < 0.008) at 12 wk of treatment, whereas at 8 wk, only the LA treatment had significantly higher plasma glucose concentrations (P < 0.001) compared with the 9c,11t CLA isomer. Although liver weights were significantly higher in 10t,12c CLA isomer-fed hamsters, liver total cholesterol, free cholesterol, cholesterol ester, and TG concentrations were significantly lower in these hamsters compared with hamsters fed the control, 9c,11t CLA isomer, and LA diets (P< 0.05). The 9c,11t CLA isomer and LA diets tended to reduce cholesterol accumulation in the aortic arch, whereas the 10t,12c CLA isomer diet tended to raise cholesterol accumulation compared with the control diet; however, neither was significant. In summary, no differences were observed between the CLA isomers for changes in plasma lipids or lipoprotein cholesterol concentrations. However, the 9c,11t CLA isomer did appear to lower plasma TG and glucose concentrations compared with the 10t,12c CLA isomer. Such differences may increase the risk of insulin resistance and type 2 diabetes in humans when the 10t,12c CLA isomer is fed separately.

Nanosphere-mediated delivery of vitamin E increases its efficacy against oxidative stress resulting from exposure to amyloid beta.

Oxidative stress is an early hallmark of affected neurons in Alzheimer's disease (AD). The antioxidant vitamin E provided limited neuroprotection in AD, which may have derived from its lipophilic nature and resultant inability to quench cytosolic reactive oxygen species (ROS), including those generated from antecedent membrane oxidative damage. We examined herein whether or not encapsulation into polyethylene glycol (PEG)-based nanospheres, which can enter the cytosol, improved the efficacy of vitamin E against amyloid-beta(Abeta)-induced ROS. Unexcapsulated vitamin E prevented Abeta-induced ROS in cultured SH-SY-5Y human neuroblastoma cells only if present prior to, or applied simultaneously with, Abeta treatment. By contrast, encapsulated vitamin E was equally effective if administered 1 hr after Abeta exposure. These findings suggest suggests that nanosphere-mediated delivery methods may be a useful adjunct for antioxidant therapy in AD.

Different palm oil preparations reduce plasma cholesterol concentrations and aortic cholesterol accumulation compared to coconut oil in hypercholesterolemic hamsters.

Several studies have reported on the effect of refined, bleached and deodorized palm oil (RBD-PO) incorporation into the diet on blood cholesterol concentrations and on the development of atherosclerosis. However, very little work has been reported on the influence of red palm oil (RPO), which is higher in carotenoid and tocopherol content than RBD-PO. Thus, we studied the influence of RPO, RBD-PO and a RBD-PO plus red palm oil extract (reconstituted RBD-PO) on plasma cholesterol concentrations and aortic accumulation vs. hamsters fed coconut oil. Forty-eight F1B Golden Syrian hamsters (Mesocricetus auratus) (BioBreeders, Watertown, MA) were group housed (three/cage) in hanging polystyrene cages with bedding in an air-conditioned facility maintained on a 12-h light/dark cycle. The hamsters were fed a chow-based hypercholesterolemic diet (HCD) containing 10% coconut oil and 0.1% cholesterol for 2 weeks at which time they were bled after an overnight fast and segregated into four groups of 12 with similar plasma cholesterol concentrations. Group 1 continued on the HCD, Group 2 was fed the HCD containing 10% RPO in place of coconut oil, Group 3 was fed the HCD containing 10% RBD-PO in place of coconut oil and Group 4 was fed the HCD with 10% reconstituted RBD-PO for an additional 10 weeks. Plasma total cholesterol (TC) and non-high-density lipoprotein-cholesterol (HDL-C) (very low- and low-density lipoprotein) concentrations were significantly lower in the hamsters fed the RPO (-42% and -48%), RBD-PO (-32% and -36%) and the reconstituted RBD-PO (-37% and -41%) compared to the coconut oil-fed hamsters. Plasma HDL-C concentrations were significantly higher by 14% and 31% in hamsters fed the RBD-PO and RPO compared to the coconut oil-fed hamsters. Plasma triglyceride (TG) concentrations were significantly lower in hamsters fed RBD-PO (-32%) and the reconstituted RBD-PO (-31%) compared to the coconut oil-fed hamsters. The plasma gamma-tocopherol concentrations were higher in the coconut oil-fed hamsters compared to the hamsters fed the RPO (60%), RBD-PO (42%) and the reconstituted RBD-PO (49%), while for plasma alpha-tocopherol concentrations, the coconut oil-fed hamsters were significantly higher than only the RPO-fed hamsters (21%). The coconut oil-fed hamsters also had significantly higher plasma lipid hydroperoxide concentrations compared to RBD-PO (112%) and the reconstituted RBD-PO (485%). The hamsters fed the coconut oil diet excreted significantly more fecal total neutral sterols and cholesterol compared to the hamsters fed the RBD-PO (158% and 167%, respectively). The coconut oil-fed hamsters had significantly higher levels of aortic total, free and esterified cholesterol compared to the hamsters fed the RPO (74%, 50% and 225%, respectively), RBD-PO (57%, 48% and 92%, respectively) and the reconstituted RBD-PO (111%, 94% and 94%, respectively). Also, aortic free/ester cholesterol ratio in the aortas of hamsters fed RPO was significantly higher than in those fed the coconut oil (124%). In conclusion, hamsters fed the three palm oil preparations had lower plasma TC and non-HDL-C and higher HDL-C concentrations while accumulating less aortic cholesterol concentrations compared to hamsters fed coconut oil.

Hypocholesterolemic effect of physically refined rice bran oil: studies of cholesterol metabolism and early atherosclerosis in hypercholesterolemic hamsters.

Physically refined rice bran oil containing 2-4% nontriglyceride components as compared to other vegetable oils appears to be associated with lipid lowering and antiinflammatory properties in several rodent, primate and human models. These experiments were designed to investigate possible mechanisms for the hypocholesterolemic effect of the physically refined rice bran oil and to examine its effect on aortic fatty streak formation. In the first experiment, 30 hamsters were fed, for 8 weeks, chow-based diets plus 0.03% added cholesterol and 5% (wt/wt) coconut, canola, or physically refined rice bran oil (COCO, CANOLA or PRBO animal groups, respectively). Both plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly reduced in PRBO but not in CANOLA relative to COCO. PRBO also showed a significant 15-17% reduction in cholesterol absorption and significant 30% increase in neutral sterol (NS) excretion with no effect on bile acid (BA) excretion. Both CANOLA and PRBO showed a significant 300-500% increase in intestinal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and significant (>25%) decrease in hepatic HMG-CoA reductase activities with respect to COCO. In a second experiment, 36 hamsters were fed chow-based diets with 0.05% added cholesterol, 10% coconut oil and 4% additional COCO, CANOLA or PRBO. Relative to COCO and CANOLA, plasma TC and LDL-C were significantly reduced in PRBO. Early atherosclerosis (fatty streak formation) was significantly reduced (48%) only in PRBO, relative to the other two. These results suggest that the lipid lowering found in PRBO is associated with decreased cholesterol absorption, but not hepatic cholesterol synthesis, and that the decrease in fatty streak formation with this oil may be associated with its nontriglyceride components not present in the other two diets.

Balance of unsaturated fatty acids is important to a cholesterol-lowering diet: comparison of mid-oleic sunflower oil and olive oil on cardiovascular disease risk factors.

OBJECTIVE: To evaluate the effects of a trans fat-free monounsaturated fatty acid-rich vegetable oil (NuSun sunflower oil, National Sunflower Association, Bismark, ND) that is a good source of polyunsaturated fatty acids (PUFA) and low in saturated fatty acids on lipid and lipoprotein levels and oxidative stress. DESIGN: A double-blinded, randomized, three period crossover, controlled feeding study. SUBJECTS/SETTING: Thirty-one men (n=12) and women (n=19) with moderate hypercholesterolemia who were 25 to 64 years of age. INTERVENTION: Experimental diets provided 30% fat (olive oil or NuSun sunflower oil contributed one half of the total fat), 8.3% vs 7.9% saturated fatty acid, 17.2% vs 14.2% monounsaturated fatty acid, and 4.3% vs. 7.7% PUFA (olive oil and NuSun sunflower oil, respectively), and 294 mg cholesterol. The control diet was an average American diet (34% fat, 11.2% saturated fatty acid, 14.9% monounsaturated fatty acid, 7.8% PUFA). Subjects consumed each diet for 4 weeks with a 2-week compliance break before crossing over to another diet. MAIN OUTCOME MEASURES: Lipid and lipoprotein levels were measured, and measures of oxidative stress, including lag time, rate of oxidation, total dienes, and lipid hydroperoxides, were assessed. STATISTICAL ANALYSIS: The mixed model procedure was used to test for main effects of diet, feeding period, and order of diets. Tukey-Kramer adjusted P values were used to determine diet effects. RESULTS: The NuSun sunflower oil diet decreased both total and low-density lipoprotein cholesterol levels compared with the average American diet and the olive oil diet. There was no effect of the olive oil diet compared with the average American diet. Total cholesterol decreased 4.7% and low-density lipoprotein cholesterol decreased 5.8% on the NuSun sunflower oil diet vs the average American diet. There was no effect of the experimental diets on triglyceride levels, rate of oxidation, total dienes, lipid hydroperoxides, or alpha-tocopherol. Lag time was the longest following the olive oil diet and shortest following the NuSun sunflower oil diet. CONCLUSIONS: The higher PUFA content appeared to account for the greater total and low-density lipoprotein cholesterol lowering and reduction in lag time of the NuSun sunflower oil diet. However, the fact that there were no differences in the resulting oxidation products suggests there were no adverse effects on low-density lipoprotein oxidation. Since PUFAs are important for cholesterol lowering, foods that replace saturated fatty acids should include a balance of unsaturated fatty acids.

Conjugated linoleic acid isomer effects in atherosclerosis: growth and regression of lesions.

Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of octadecadienoic acid, has been shown to inhibit experimentally induced atherosclerosis in rabbits and also to cause significant regression of pre-established atheromatous lesions in rabbits. The two major CLA isomers (cis9,trans11 and trans10,cis12), now available at 90% purity, have been tested individually for their anti-atherogenic or lesion regression potency. The two major isomers and the mixture were fed for 90 d to rabbits fed 0.2% cholesterol. Atherosclerosis was inhibited significantly by all three preparations. The two CLA isomers and the isomer mix were also fed (1.0%) as part of a cholesterol-free diet for 90 d to rabbits bearing atheromatous lesions produced by feeding an atherogenic diet. A fourth group was maintained on a cholesterol-free diet. On the CLA-free diet atherosclerosis was exacerbated by 35%. Reduction of severity of atheromatous lesions was observed to the same extent in all three CLA-fed groups. The average reduction of severity in the three CLA-fed groups was 26 +/- 2% compared with the first control (atherogenic diet) and 46 +/- 1% compared with the regression diet. Insofar as individual effects on atherosclerosis were concerned, there was no difference between the CLA mix and the cis9,trans11 and trans10,cis12 isomers. They inhibit atherogenesis by 50% when fed as a component of a semipurified diet containing 0.2% cholesterol; and when fed as part of a cholesterol-free diet, they reduce established lesions by 26%. Reduction of atheromata to the observed extent by dietary means alone is noteworthy.

Reduced and high molecular weight barley beta-glucans decrease plasma total and non-HDL-cholesterol in hypercholesterolemic Syrian golden hamsters.

Consumption of concentrated barley beta-glucan lowers plasma cholesterol because of its soluble dietary fiber nature. The role of molecular weight (MW) in lowering serum cholesterol is not well established. Prior studies showed that enzymatic degradation of beta-glucan eliminates the cholesterol-lowering activity; however, these studies did not evaluate the MW of the beta-glucan. The current study was conducted to evaluate whether barley beta-glucan concentrates, partially hydrolyzed to reduce MW, possess cholesterol-lowering and antiatherogenic activities. The reduced MW fraction was compared with a high MW beta-glucan concentrate from the same barley flour. Concentrated beta-glucan preparations were evaluated in Syrian Golden F(1)B hamsters fed a hypercholesterolemic diet (HCD) with cholesterol, hydrogenated coconut oil, and cellulose. After 2 wk, hamsters were fed HCD or diets that contained high or reduced MW beta-glucan at a concentration of 8 g/100 g at the expense of cellulose. Decreases in plasma total cholesterol (TC) and non-HDL-cholesterol (non-HDL-C) concentrations occurred in the hamsters fed reduced MW and high MW beta-glucan diets. Plasma HDL-C concentrations did not differ. HCD-fed hamsters had higher plasma triglyceride concentrations. Liver TC, free cholesterol, and cholesterol ester concentrations did not differ. Aortic cholesterol ester concentrations were lower in the reduced MW beta-glucan-fed hamsters. Consumption of either high or reduced MW beta-glucan increased concentrations of fecal total neutral sterols and coprostanol, a cholesterol derivative. Fecal excretion of cholesterol was greater than in HCD-fed hamsters only in those fed the reduced MW beta-glucan. Study results demonstrate that the cholesterol-lowering activity of barley beta-glucan may occur at both lower and higher MW.

Decreased aortic early atherosclerosis and associated risk factors in hypercholesterolemic hamsters fed a high- or mid-oleic acid oil compared to a high-linoleic acid oil.

Currently, diets higher in polyunsaturated fat are believed to lower blood cholesterol concentrations, and thus reduce atherosclerosis, greater than diets containing high amounts of saturated or possibly even monounsaturated fat. The present study was designed to investigate the effect of diets containing mid- or high-linoleic oil versus the typical high-linoleic sunflower oil on LDL oxidation and the development of early atherosclerosis in a hypercholesterolemic hamster model. Animals were fed a hypercholesterolemic diet containing 10% mid-oleic sunflower oil, high-oleic olive oil, or high-linoleic sunflower oil (wt/wt) plus 0.4% cholesterol (wt/wt) for 10 weeks. After 10 weeks of dietary treatment, only the animals fed the mid-oleic sunflower oil had significant reductions in plasma LDL-C levels (-17%) compared to the high-linoleic sunflower oil group. The high-oleic olive oil-fed hamsters had significantly higher plasma triglyceride levels (+41%) compared to the high-linoleic sunflower oil-fed hamsters. The tocopherol levels in plasma LDL were significantly higher in hamsters fed the mid-oleic sunflower oil (+77%) compared to hamsters fed either the high-linoleic sunflower or high-oleic olive oil. Measurements of LDL oxidation parameters, indicated that hamsters fed the mid-oleic sunflower oil and high-oleic olive oil diets had significantly longer lag phase (+66% and +145%, respectively) and significantly lower propagation rates (-26% and -44%, respectively) and conjugated dienes formed (-17% and -25%, respectively) compared to the hamsters fed the high-linoleic sunflower oil. Relative to the high-linoleic sunflower oil, aortic cholesterol ester was reduced by -14% and -34% in the mid-oleic sunflower oil and high-oleic olive oil groups, respectively, with the latter reaching statistical significance. Although there were no significant associations between plasma lipids and lipoprotein cholesterol with aortic total cholesterol and cholesterol esters for any of the groups, the lag phase of conjugated diene formation was inversely associated with both aortic total and esterified cholesterol in the high-oleic olive oil-fed hamsters (r = -0.69, P < 0.05). The present study suggests that mid-oleic sunflower oil reduces risk factors such as lipoprotein cholesterol and oxidative stress associated with early atherosclerosis greater than the typical high-linoleic sunflower oil in hypercholesterolemic hamsters. The high-oleic olive oil not only significantly reduced oxidative stress but also reduced aortic cholesterol ester, a hallmark of early aortic atherosclerosis greater than the typical high-linoleic sunflower oil.

Hamsters fed diets high in saturated fat have increased cholesterol accumulation and cytokine production in the aortic arch compared with cholesterol-fed hamsters with moderately elevated plasma non-HDL cholesterol concentrations.

There is growing evidence that dietary fatty acids and/or dietary cholesterol could have a direct role on inflammatory diseases such as atherosclerosis. F(1)B Golden Syrian hamsters (Mesocricetus auratus), in 2 groups of 72, were fed for 10 wk a semipurified diet containing either 20 g/100 g hydrogenated coconut oil without cholesterol or cocoa butter (20 g/100 g) with cholesterol (0.15 g/100 g). After the 10-wk treatment period, plasma was collected from food-deprived hamsters (16 h) for plasma lipid measurements. Hamsters were then ranked according to their plasma VLDL and LDL cholesterol (non-HDL-C) concentrations with 1.86 mmol/L as the cut-off point between low (Low; n = 36) and medium (Med; n = 36) concentrations for each treatment. Hamsters in the Low and Medium groups fed cholesterol (Low-chol) had significantly lower plasma total cholesterol (TC) concentrations than hamsters in the Low group fed coconut oil (Low-CO). However, this difference for the Medium group was reflected in significantly lower plasma HDL cholesterol (HDL-C) concentrations. Hamsters in the Low-CO group had significantly higher aortic total and esterified cholesterol concentrations than hamsters in the Low-chol group. Hamsters in the Low-chol group had significantly higher aortic tumor necrosis factor-alpha concentrations than hamsters in the Low-CO group. Hamsters in the Med-CO group had significantly higher aortic interleukin-1beta concentrations than hamsters in the Med-chol group. In conclusion, the present study suggests that dietary cholesterol and saturated fatty acids could have an effect on atherosclerosis not only beyond their role in affecting plasma lipoproteins but also through increased production of inflammatory cytokines in the arterial wall.