The effect of dietary protein source on plasma cholesterol level and fecal steroid excretion in obese mice.Both goldthioglucose (GTG)-treated and the genetically obese (C57BL/6J ob/ob) mice were fed semisynthetic diets containing either soy protein isolate (SPI) or casein as a protein source, or laboratory chow. In GTG-induced obese mice, the plasma cholesterol level correlated positively with their body weight. The level was highest in mice fed high-fat diet, and lowest in ones fed laboratory chow. No difference was observed between SPI and casein groups whether the diet was low-fat or high-fat. Thus, in the GTG-treated mice, SPI did not have a hypocholesterolemic effect while dietary fat had a hypercholesterolemic effect, and laboratory chow contained some component(s) which can lower the plasma cholesterol level. Both neutral and acidic steroid contents in feces of the SPI group were not different from those of the casein group, and both groups of mice excreted a smaller amount of steroids than mice fed laboratory chow. Results of essentially the same tendency were obtained with normal mice regarding the effects of SPI and casein, although the degree of hypercholesterolemia was lower in high-fat-fed normal mice than in similarly fed GTG-treated mice. These results strengthened the inverse correlation between the amount of fecal steroids and the plasma cholesterol level upon feeding various proteins, indicating that the former is one of the important factors that determine the latter. The ob/ob mice showed a marked hypercholesterolemia irrespective of the kind of diet. The amount of fecal steroids was highest in the laboratory chow group and lowest in the casein group. This indicates that some factor(s) other than fecal steroid excretion is dominantly responsible for their hypercholesterolemia.

Serum cholesterol predictive equations in product development.The aim of the study was to incorporate trans fatty acids into predictive equations for serum cholesterol and compare their effects with the effects of the individual saturated fatty acids 12:0, 14:0 and 16:0. We have introduced trans fatty acids from partially hydrogenated soybean oil (TransV) and fish oil (TransF) into previously published equations by constrained regression analysis. Prior knowledge about the signs and ordering of existing regression coefficients were incorporated into the regression modelling by adding lower and upper bounds to the coefficients. Oleic acid (18:1) and polyunsaturated fatty acids (18:2, 18:3) were not sufficiently varied in the studies and the respective regression coefficients therefore set equal to those found by Yu et al. (Am J Clin Nutr 1995;61:1129-39). Stearic acid (18:0) considered to be neutral was not included in the equations. The regression analyses were based on results from four controlled dietary studies with a total of 95 participants and including 10 diets differing in fatty acid composition. The analyses resulted in the following equations where the change in cholesterol is expressed in mmol/L and the change in intake of fatty acids is expressed in E%: Delta Total cholesterol = 0.01 delta(12:0) + 0.12 Delta(14:0) + 0.057 delta(16:0) + 0.039 delta(TransF) + 0.031 delta(TransV)- 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3) and deltaLDL cholesterol = 0.01 delta(12:0) + 0.071 delta(14:0) + 0.047 delta(16:0) + 0.043 delta(TransF) + 0.025 delta(TransV) - 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3). The test set used for validation consisted of 22 data points from seven recently published dietary studies. The equation for total cholesterol showed good prediction ability with a correlation coefficient of 0.981 between observed and predicted values. The equation has been used to reformulate margarines into "trans free" products all with more favourable effects on serum cholesterol than previous products. Also a cholesterol reducing margarine has been produced. When tested against butter in an open clinical trial among subjects with mild hypercholesterolemia the observed cholesterol-lowering effect of this margarine corresponded reasonably well with the predicted (0.77 vs. 0.64 mmol/L). We conclude that the equation has practical applicability and can be used to formulate and nutritionally optimise fat products as well as to evaluate already existing products on the market.

Effectiveness and hazards of case finding for a high cholesterol concentration.OBJECTIVE--To see whether adults with high blood cholesterol concentrations (greater than 6.5 mmol/l) detected by case finding return to their doctor, receive appropriate advice, and report changes in their diet and whether adults found not to have high cholesterol concentrations on case finding are discouraged from changing their diet. DESIGN--Follow up study. SETTING--Seven general practices in the lower Hunter region of Australia. PARTICIPANTS--600 Men and women aged 25-65 who had their blood cholesterol concentrations measured three to four months earlier while attending their general practitioner. Analysis conducted on 552 (92%) who returned follow up postal questionnaires. MEASUREMENTS AND MAIN RESULTS--Of the 125 subjects found to have blood cholesterol concentrations greater than 6.5 mmol/l, 102 (82%) returned to their doctor and 83 of these recalled receiving dietary advice. 93 (75%) Subjects with high concentrations reported changing their diet compared with 72 (46%) subjects with concentrations of greater than 5.5-6.5 mmol/l and 44 (17%) subjects with lower concentrations. Overall 333 (61%) of all respondents who answered reported not changing their diet, the most common reason (nearly half the sample; n = 266) being that their cholesterol concentration was "all right." Adults without high cholesterol concentrations who returned to their doctor were also significantly more likely to recall their doctor saying that they did not need to lower their concentrations (less than or equal to 5.5 mmol/l = 61%; greater than 5.5-6.5 mmol/l = 12%; greater than 6.5 mmol/l = 5%) and significantly less likely to recall receiving dietary advice (less than or equal to 5.5 mmol/l = 13%; greater than 5.5-6.5 mmol/l = 60%; greater than 6.5 mmol/l = 82%). CONCLUSIONS--High risk strategies which require everyone to be tested for high cholesterol concentrations may interfere with population strategies designed to reduce everyone's dietary intake of fat.

Influence of the trapidil derivative AR 12463 on serum and tissue lipids and development of aortic lesions during experimental atherosclerosis in rabbits.Daily administration of the trapidil derivative AR 12463 (20 mg/kg body weight i.p.) to cholesterol-fed rabbits diminished statistically significantly the increase in serum total cholesterol. After 8 weeks of treatment all measured lipoprotein fractions were significantly lower in animals treated with AR 12463 (group 3) compared with the values of the untreated control (group 1) or vehicle-treated group (group 2). The reduction of serum levels was associated with statistically significantly reduced levels of cholesterol esters in kidney, liver and aorta. The levels of free cholesterol in the liver of group 3 animals were statistically significantly lower compared with the levels in the two other groups, whereas in kidney and aortas the levels of free cholesterol remained unchanged under the influence of AR 12463. The area of aorta covered with fatty streaks was significantly smaller in group 3 versus group 1. The results of this study indicate that treatment of rabbits with AR 12463 while feeding a cholesterol-rich diet prevents hypercholesterolemia as well as the cholesterol incorporation into tissues. The mode of action of AR 12463 on serum and tissue lipids as well as on the development of atherosclerosis is discussed.

Coronary artery disease and infection with chlamydia pneumonia.The association between chlamydia pneumonia and coronary artery disease is well documented, however less is known about the correlation between chlamydia pneumonia infection and blood inflammatory markers or lipid levels. In 100 patients with proven coronary artery disease (25 females, 61.0 +/- 4.0 years old), and 60 healthy volunteer control cases (15 females, 60.6 +/- 3.4 years old), anti chlamydia pneumonia IgG, blood lipid, C-reactive protein and fibrinogen levels were detected. In cases with coronary artery disease seropositivity for IgG antibodies to chlamydia pneumonia (74% versus 34%, p < 0.0001), C-reactive protein (mg / l) (2.8 +/- 0.6 versus 1.4 +/- 0.6; p < 0.0001), fibrinogen (mg / dl) (317.4 +/- 38.2 versus 256.2 +/- 34.5, p < 0.0001), triglyceride (mg / dl) (217.5 +/- 39.0 versus 191.0 +/- 25.9, p < 0.0001), LDL-cholesterol (mg / dl) (126.9 +/- 19.2 versus 110.6 +/- 19.5, p < 0.0001) levels and total cholesterol / HDL-cholesterol ratio (7.7 +/- 1.8 versus 4.4 +/- 1.2, p < 0.0001) were higher but the level of HDL-cholesterol (mg / dl) (26.4 +/- 6.7 versus 47.0 +/- 11.2, p < 0.0001) was lower. The levels of total cholesterol did not differ between the two groups (p=0.9). Levels of triglyceride (r=0.60, p < 0.00001), LDL-cholesterol (r = 0.27, p = 0.0004), C-reactive protein (r = 0.69, p < 0.00001), fibrinogen (r = 0.60, p < 0.00001) and total cholesterol / HDL-cholesterol ratio (r = 0.74, p < 0.00001) had a direct relation, but the level of HDL-cholesterol had a negative (r= -0.80, p < 0.00001) relation with the seropositivity for chlamydia pneumonia. As a result, seropositivity for IgG antibodies to chlamydia pneumonia is considered as a risk factor for coronary artery disease by its association with the atherogenic lipid profile and procoagulant activity.

The effect of vitamin C in high doses on plasma and biliary lipid composition in patients with cholesterol gallstones: prolongation of the nucleation time.Vitamin C deficiency in guinea pigs leads to cholesterol supersaturation of bile and formation of cholesterol gallstones. It has been suggested that there may also exist an association between vitamin C and cholesterol gallstones in man, but such a relationship has not been studied in gallstone patients. In order to study the possible effects of vitamin C on gallstone disease in humans, plasma lipid levels, hepatic cholesterol metabolism, biliary lipid composition, cholesterol saturation and nucleation time of gallbladder bile were analysed in 16 consecutive gallstone patients, who were planned for laparoscopic cholecystectomy and were treated with vitamin C (500 mg, four times a day) for 2 weeks before surgery. The plasma concentration of vitamin C increased by 42% in the treatment group. The concentrations of plasma lipids did not differ before and after vitamin C treatment; nor did the plasma levels of lathosterol and 7 alpha-hydroxy-4-cholesten-3-one, reflecting cholesterol and bile acid synthesis respectively. The relative concentrations of cholesterol, bile acids and cholesterol concentration of bile did not differ significantly between the two groups, but the relative concentration of phospholipids was slightly higher in the treated group. The bile acid composition was changed; the percentage of cholic acid being lower and those of deoxycholic acid, ursodeoxycholic acid and lithocholic acid higher in the vitamin C-treated patients compared with the untreated group. The nucleation time was significantly longer in the treatment group (7 days) compared with the untreated group (2 days). Our findings indicate that vitamin C supplementation may also influence the conditions for cholesterol gallstone formation in humans.

Gender differences in response to a hypercholesterolemic diet in hamsters: effects on plasma lipoprotein cholesterol concentrations and early aortic atherosclerosis.Gender is a strong predictor of Coronary Heart Disease (CHD) susceptibility and reports indicate that males are more likely to develop CHD compared to age-matched premenopausal females. To test whether similar gender differences exist in hamsters, 16 male and 16 female F1B Golden Syrian hamsters, aged 10 weeks, were fed a hypercholesterolemic nonpurified diet (HCD) containing 10% coconut oil and 0.05% cholesterol for 12 weeks. Plasma lipid and lipoprotein cholesterol concentrations, LDL oxidative susceptibility, LDL tocopherol concentrations, LDL fatty acid composition, LDL particle size, plasma estradiol and testosterone concentrations, and early aortic atherosclerosis were analyzed. Female hamsters had significantly lower plasma total cholesterol and nonhigh-density lipoprotein cholesterol (nonHDL-C) and greater high-density lipoprotein cholesterol (HDL-C) concentrations compared to male hamsters (-15, -33, and 33%; respectively). Female hamsters had significantly greater LDL particle size (4%), LDL 22:6 (21%) fatty acid, and rate of LDL oxidation (34%) compared to male hamsters. Female hamsters had a significantly higher concentration of plasma estradiol (49%) compared to male hamsters. Female hamsters also had significantly less early aortic atherosclerosis compared to male hamsters (-77%). In female hamsters, aortic fatty streak formation was significantly associated with plasma nonHDL-C (r = 0.76, P<0.0007), LDL particle size (r = -0.66, P<0.005), plasma TC (r = 0.68. P<0.004), and lag phase of LDL oxidation (r = 0.84. P<0.02). In male hamsters, aortic fatty streak formation was significantly associated with plasma nonHDL-C (r = 0.52, P<0.04), plasma TC (r = 0.55, P<0.03), plasma TG (r = 0.79, P<0.0003), and LDL 22:6 (r = -0.78, P<0.03) with no association with any measures of LDL oxidation susceptibility. This study demonstrates that female hamsters have an improved plasma lipoprotein cholesterol profile, larger LDL particle size, and less early aortic atherosclerosis compared to male hamsters fed the same HCD.

Lipid metabolism in hypercholesterolemic rats affected by feeding cholesterol-free diets containing different amounts of non-dialyzed soybean protein fraction.OBJECTIVE: We investigated lipid metabolism in hypercholesterolemic rats after replacing casein with different amounts of undialyzed soybean protein fraction. METHODS: The hypercholesterolemic rats were fed cholesterol-free diets containing 2%, 5%, or 10% undialyzed soybean protein fraction (UDSP) for 4 wk. RESULTS: The 5% and 10% UDSP groups had significantly lower plasma cholesterol, triacylglycerol, and low-density lipoprotein cholesterol concentrations than did the other groups (P < 0.05). In addition, significantly higher fecal total steroid excretion was observed in these two groups. However, the different amounts of UDSP did not influence liver lipid, plasma high-density lipoprotein cholesterol, body weight gain, daily food intake, or feeding efficiency. CONCLUSION: These results suggested a dose-dependent reduction in plasma cholesterol when casein was replaced stepwise with UDSP (5% or 10%) as a protein source. The hypocholesterolemic effect might have been due to an increase in total fecal steroid excretion.

The pentaene macrolide antibiotic filipin prefers more rigid DPPC bilayers: a fluorescence pressure dependence study.Filipin is a pentaene macrolide antibiotic which was previously shown to incorporate more extensively into DPPC bilayers below the main phase transition temperature than above this temperature. This result was extremely unusual because drugs tend to be expelled from ordered gel phases. However, such results could not be safely attributed to the phase change of the bilayer itself because the temperature was changing concomitantly. In this work we changed the bilayer phase isothermally (53 degrees C) by hydrostatic pressure variation and discovered that filipin has a slightly more extensive incorporation in the pure DPPC gel phase (P>ca. 54.4 MPa): Kp,lc approximately 3x10(3) vs. Kp,gel approximately 6x10(3). The presence of sterols (45% molar ergosterol or cholesterol) caused an increase in the partition coefficients, regardless of pressure, ergosterol having a more pronounced effect (Kp approximately 2x10(4)-6x10(4)). Kp was pressure dependent in both cases, but mainly with cholesterol (Kp approximately 2x10(3)-2x10(4)). At variance with cholesterol, when ergosterol was used, no phase transition was detected. This difference cannot be due to a more extended uptake of filipin by cholesterol-containing membranes, and so must be due to specific interactions with cholesterol. In agreement with this finding, we discovered that filipin is more tightly packed (lower partial molar volume) in the cholesterol-rich phase than in the ergosterol-rich phase. Our results also point to a 2:1 DPPC:cholesterol stoichiometry in the cholesterol-rich phase (17% molar cholesterol). All partition coefficients were calculated from steady-state fluorescence anisotropy measurements.

Dietary polyenylphosphatidylcholine decreases cholesterolemia in hypercholesterolemic rabbits: role of the hepato-biliary axis.The aim of this work was to study the cholesterol-lowering mechanisms induced by dietary soybean lecithin in hypercholesterolemic rabbits. Male New Zealand white rabbits (n = 6 in each group) were fed for 10 weeks either a low-fat control C diet, containing 27 g fat/kg, or high-fat diets enriched with 2 g cholesterol/kg and 77 g fat/kg. The high-fat diets contained 50 g lard (L), 50 g soybean triacylglycerol (SO), or 50 g pure soybean phosphatidylcholine (PLE). PLE diet decreased by 30% beta-VLDL-cholesterol, compared with SO diet. HDL2-, HDL3- and LDL-lipid contents were unchanged in the L, SO and PLE groups. In gallbladder bile, amounts of phospholipids, bile salts and cholesterol were significantly increased in PLE group by respectively 45%, 11% and 44%, in comparison with SO group. Intestinal and hepatic Hydroxy Methyl Glutaryl Coenzyme A reductase activities were not increased by PLE diet. Triacylglycerol hepatic content was lower in PLE group than in L or SO groups. Compared with triacylglycerol enriched diet, phosphatidylcholine enriched diet developed significant higher cholesterol- and triacylglycerol-lowering effects by a two-step mechanism: i) by reducing the beta-VLDLs, ii) by enhancing the secretion of bile cholesterol. Such results constitute promising effects of soybean phosphatidylcholine at the hepato-biliary level, in the treatment or prevention of hyperlipidemia and related atherosclerosis.