| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Effects of pectin in the ration on cholesterol metabolism in rats Georgieva, N. B. (1992), Vopr Pitan(2): 47-50. Abstract: Inclusion into the ration of 2.5 or 5% of apple pectin during 20 days did not significantly change the blood serum composition: cholesterol content decreased as compared to the control, the number of general bile acids increased. When apple pectin was added to the animals' ration containing egg powder, the amount of cholesterol excreted with feces increased depending on pectin content in the food. |
| Effects of PEG-lipids on permeability of phosphatidylcholine/cholesterol liposomes in buffer and in human serum Silvander, M., M. Johnsson, et al. (1998), Chem Phys Lipids 97(1): 15-26. Abstract: The permeability of liposomal membranes was studied as a function of the amount of incorporated PEG-lipid. The fluorescent dyes ethidium, propidium and 5(6)-carboxy fluorescein were used as markers for measurements of spontaneous leakage. The results show that addition of up to 8 mol% of PEG(2000)-DSPE into liposomal membranes of DSPC/Cho and EPC/Cho reduces the permeability of carboxyfluorescein in buffer solution. In contrast, the leakage of the more amphiphilic dye ethidium was not to any measurable extent affected by PEG-lipid inclusion. Another important difference was that ethidum leakage showed a clear dependence on temperature whereas leakage of carboxyfluorescein from pegylated liposomes did not. We conclude that the mechanisms by which the two dyes permeate the liposomal bilayer are qualitatively different. Both ethidium and carboxyfluorescein did interact with human serum components in a way that made measurements in serum unreliable. The more hydrophilic ethidium analogue propidium was shown not to interact with human serum components to any detectable extent. This made propidium suitable for permeability determinations in human serum. It was found that liposomes composed of pure EPC or EPC with 5 mol% DSPE-PEG, displayed a dramatic increase in permeability when subjected to a medium composed of 20% human serum in buffer. Addition of 40 mol% cholesterol to the EPC bilayers reduced the observed release rate in human serum substantially, whereas no stabilizing effect was observed upon PEG-lipid inclusion. |
| Effects of perfluorodecanoic acid on de novo fatty acid and cholesterol synthesis in the rat Davis, J. W., 2nd, J. P. Vanden Heuvel, et al. (1991), Lipids 26(10): 857-9. Abstract: Perfluorodecanoic acid (PFDA) is a peroxisome proliferator that causes a dose-dependent (20-80 mg/kg) increase in hepatic triacylglycerol and cholesteryl ester levels in the rat. We hypothesized that PFDA may cause an increase in the de novo synthesis of fatty acids and cholesterol in this species, which would explain observed effects. The incorporation of 3H2O into tissue lipids was examined 7 days after rats received vehicle or 20 or 80 mg/kg of PFDA. PFDA treatment decreased the rate of synthesis of cholesterol and fatty acids in the live and in epididymal fat pad. At a PFDA dose (20 mg/kg) that decreased de novo synthesis of fatty acids and cholesterol, there was no effect on the concentration of fatty acids and cholesterol in the liver, epididymal fat pads, and plasma. We conclude that PFDA induced fatty liver is due to either a decrease in the oxidation of fatty acids in the liver, or an impairment of triacylglycerol catabolism and/or export from the liver, and is not the result of an increase in de novo synthesis of fatty acids and cholesterol. |
| Effects of peroxisome proliferator-activated receptor alpha activation on pathways contributing to cholesterol homeostasis in rat hepatocytes Le Jossic-Corcos, C., S. Duclos, et al. (2004), Biochim Biophys Acta 1683(1-3): 49-58. Abstract: Peroxisome proliferator-activated receptor alpha (PPARalpha) activation by fibrates controls expression of several genes involved in hepatic cholesterol metabolism. Other genes could be indirectly controlled in response to changes in cellular cholesterol availability. To further understand how fibrates may affect cholesterol synthesis, we investigated in parallel the changes in the metabolic pathways contributing to cholesterol homeostasis in liver. Ciprofibrate increased HMG-CoA reductase and FPP synthase mRNA levels in rat hepatocytes, together with cholesterogenesis from (14)C acetate and (3)H mevalonate. The up-regulation observed in fenofibrate- and WY-14,643-treated mice was abolished in PPARalpha-null mice, showing an essential role of PPARalpha. Among the three sterol regulatory element-binding protein (SREBP) mRNA species, only SREBP-1c level was significantly increased. In ciprofibrate-treated hepatocytes, cholesterol efflux was decreased, in parallel with cholesteryl ester storage and bile acids synthesis. As expected, AOX expression was strongly induced, supporting evidence of the peroxisome proliferation. Taken together, these results show that fibrates can cause cholesterol depletion in hepatocytes, possibly in part as a consequence of an important requirement of cholesterol for peroxisome proliferation, and increase cholesterogenesis by a compensatory phenomenon afterwards. Such cholesterogenesis regulation could occur in vivo, in species responsive to the peroxisome proliferative effect of PPARalpha ligands. |
| Effects of peroxisome proliferators gemfibrozil and clofibrate on syntheses of dolichol and cholesterol in rat liver Shiota, Y., M. Ikeda, et al. (2003), J Biochem (Tokyo) 134(2): 197-202. Abstract: The effects of two peroxisome proliferators, gemfibrozil and clofibrate, on syntheses of dolichol and cholesterol in rat liver were investigated. Gemfibrozil did not affect the overall content of dolichyl phosphate, but it changed the chain-length distribution of dolichyl phosphate, increasing the levels of species with shorter isoprene units. Gemfibrozil suppressed synthesis of dolichyl phosphate from (3)Hmevalonate and (3)Hfarnesyl pyrophosphate in rat liver. In contrast, clofibrate increased the content of dolichol (free and acyl ester forms). It remarkably enhanced dolichol synthesis from mevalonate, but did not affect dolichol synthesis from farnesyl pyrophosphate. Gemfibrozil elevated cholesterol synthesis from (14)Cacetate, but did not affect the synthesis from mevalonate. Clofibrate suppressed cholesterol synthesis from acetate, but did not affect cholesterol synthesis from mevalonate. These results suggest that gemfibrozil suppresses synthesis of dolichyl phosphate by inhibiting, at the least, the pathway from farnesyl pyrophosphate to dolichyl phosphate. As a result, the chain-length pattern of dolichyl phosphate may show an increase in shorter isoprene units. Clofibrate may increase the content of dolichol by enhancing dolichol synthesis from mevalonate. Gemfibrozil may increase cholesterol synthesis by activating the pathway from acetate to mevalonate. Unlike gemfibrozil, clofibrate may decrease cholesterol synthesis by inhibiting the pathway from acetate to mevalonate. |
| Effects of peroxynitrite on plasma components of the reverse cholesterol transport pathway Graham, A., D. V. Vinogradov, et al. (1998), FEBS Lett 431(3): 327-32. Abstract: Elimination of cholesterol from arterial tissue, crucial in limiting atherogenesis, may be achieved via high-density lipoprotein (HDL)-mediated reverse cholesterol transport (RCT); components of this pathway can be modulated by oxidative stress. Here we have examined the relations between cholesterol efflux, esterification and transfer in human plasma treated with the powerfully reactive nitrogen species, peroxynitrite. Cellular cholesterol efflux to whole plasma, or to peroxynitrite-modified HDL3, was relatively insensitive to peroxynitrite, as was the transfer of esterified cholesterol. However, plasma cholesterol esterification, via lecithin:cholesterol acyltransferase (LCAT), was markedly inhibited, both directly and indirectly, by peroxynitrite treatment, implying inefficient RCT follows HDL sequestration of cellular cholesterol. |
| Effects of perturbations in hepatic free and esterified cholesterol pools on bile acid synthesis, cholesterol 7 alpha-hydroxylase, HMG-CoA reductase, acyl-CoA:cholesterol acyltransferase and cytosolic cholesteryl ester hydrolase Grogan, W. M., M. L. Bailey, et al. (1991), Lipids 26(11): 907-14. Abstract: Effects of expansion of the hepatic free cholesterol pool on bile acid and cholesterol metabolism and homeostasis were examined in rats fed cholesterol in high-fat diets or treated with oleyl-p-(n-decyl)-benzenesulfonate (ODS) or progesterone. Cholesterol feeding for 10-16 days, which increased free (33%) and esterified (6-fold) cholesterol, had no effect on cholate synthesis, total bile acid synthesis, or cholate turnover, whereas these activities were increased 60-80% by ODS and progesterone, which produced only small increases (19%) in free cholesterol. Cholesterol feeding reduced beta-hydroxy-beta-methylglutaryl (HMG)-CoA reductase (72%) and cholesteryl ester hydrolase (48%) and increased acyl-CoA:cholesterol acyltransferase (184%), whereas ODS and progesterone reversed these compensatory responses in cholesterol-fed rats. Cholesterol 7 alpha-hydroxylase was changed no more than 22% by any treatment. A bolus of ODS elevated biliary cholesterol output 41% and shifted biliary bile acid synthesis and composition toward 12-deoxy bile acids. These effects were not seen in ODS-fed or progesterone-treated rats, in which cholesteryl ester stores were depleted. It is concluded that effects of free cholesterol on bile acid synthesis and biliary cholesterol are probably mediated by specific precursor or regulatory pools which can be independently regulated and which represent a relatively small fraction of hepatic free cholesterol. |
| Effects of pH and cholesterol on DMPA membranes: a solid state 2H- and 31P-NMR study Pott, T., J. C. Maillet, et al. (1995), Biophys J 69(5): 1897-908. Abstract: The effect of pH and cholesterol on the dimyristoylphosphatidic acid (DMPA) model membrane system has been investigated by solid state 2H- and 31P-NMR. It has been shown that each of the three protonation states of the DMPA molecule corresponds to a 31P-NMR powder pattern with characteristic delta sigma values; this implies additionally that the proton exchange on the membrane surface is slow on the NMR time scale (millisecond range). Under these conditions, the 2H-labeled lipid chains sense only one magnetic environment, indicating that the three spectra detected by 31P-NMR are related to charge-dependent local dynamics or orientations of the phosphate headgroup or both. Chain ordering in the fluid phase is also found to depend weakly on the charge at the interface. In addition, it has also been found that the first pK of the DMPA membrane is modified by changes in the lipid lateral packing (gel or fluid phases or in the presence of cholesterol) in contrast to the second pK. The incorporation of 30 mol% cholesterol affects the phosphatidic acid bilayer in a way similar to what has been reported for phosphatidylcholine/cholesterol membranes, but to an extent comparable to 10-20 mol % sterol in phosphatidylcholines. However, the orientation and molecular order parameter of cholesterol in DMPA are similar to those found in dimyristoylphosphatidylcholine. |
| Effects of phenytoin on plasma high-density lipoprotein cholesterol levels in men with low levels of high-density lipoprotein cholesterol Goerdt, C., M. Keith, et al. (1995), J Clin Pharmacol 35(8): 767-75. Abstract: A low level of high-density lipoprotein cholesterol (HDL-C) is an important and common risk factor for coronary heart disease. Cross-sectional studies and uncontrolled clinical trials have suggested that phenytoin can significantly raise HDL-C levels. This study was undertaken to determine whether phenytoin can raise HDL-C levels in men with low levels of HDL-C. Ninety-two men currently receiving outpatient care at a Veterans Affairs medical center and with baseline HDL-C levels < or = 1.16 mmol/L (45 mg/dL) were recruited to participate in this randomized, placebo-controlled, double-blind clinical trial. Participants received a placebo or 100 mg, 200 mg, or 300 mg of phenytoin once daily for 14 weeks. Lipid levels were measured at baseline and at 6, 10, and 14 weeks. After 14 weeks of treatment, the 200-mg and 300-mg phenytoin groups together achieved a significant 10% increase in HDL-C levels compared with placebo after adjusting for differences in baseline HDL-C levels, age, and body mass index. Other lipid levels did not significantly change in the phenytoin groups compared with placebo. Average compliance was 98% or greater for each of the treatment groups. Eighteen participants dropped out of the study with similar numbers from each treatment group. Side effects were mild and mostly transient. Low doses of phenytoin are well tolerated and can effectively increase HDL-C levels in men with low levels of HDL-C. |
| Effects of phosphatidylcholine/phosphatidylethanolamine composition in cholesteryl ester-micellar substrates on neutral cholesterol esterase activity Chiba, T., S. Uematsu, et al. (1999), Anal Biochem 268(2): 238-44. Abstract: The effect of phospholipid composition in cholesteryl ester (CE)-micellar substrates on neutral cholesterol esterase (N-CEase) activity was examined. N-CEase preparation was incubated with micelles composed of cholesteryl-1-14C-oleate, sodium taurocholate, and phosphatidylcholine (PC)/phosphatidylethanolamine (PE) at varying ratios (%PE:0 = PC only, 17, 33, 50, 66, 83). The activity increased dependently with the increase in PE content; the activity with the micelles containing the highest ratio of PE was 2.5-fold compared with the micelles consisting of PC only. Vmax with the micelles of 83, 66, and 50% PE was 3.1-, 2.7-, and 1.9-fold, respectively, compared with the micelles of PC only. Each micellar preparation was chromatographed through a Superose 6 column by the FPLC system. In 66 and 83% PE-containing micelles, PC, PE, CE, and part of sodium taurocholate eluted completely together in a single peak, whereas in micelles with 33 and 50% PE they eluted loosely together. The micelles with PC only or 17% PE formed PC-micelles without including CE and PE. It is concluded that PE plays a critical role in the formation of CE micelles with PC, and in the interaction with N-CEase. The CE-micelles with 66-83% PE serve as substrates for sensitive and reproducible N-CEase assay. |
| Effects of phosphatidylserine and cholesterol liposomes on the viability, motility, and acrosomal integrity of stallion spermatozoa prior to and after cryopreservation Wilhelm, K. M., J. K. Graham, et al. (1996), Cryobiology 33(3): 320-9. Abstract: Computer-assisted motion analyses (CASA) and flow cytometry were used to evaluate stallion spermatozoa prior to and after cryopreservation. Spermatozoa were pretreated with: (1) Hepes-buffered medium (SHB); (2) phosphatidylserine (PS) liposomes; or (3) liposomes composed of both PS and cholesterol (PSCH) prior to dilution in either SHB or skim milk-egg yolk extender (SMEY). After cooling to 5 degrees C in SHB, PS and PSCH pretreatment (23%). Spermatozoal motion parameters were higher for spermatozoa diluted in SMEY than dilution in SHB. In Experiment 2, motion parameters were compared for spermatozoa pretreated with PSCH liposomes and cryopreserved in either SMEY or a high salt-skim milk-egg yolk extender (CO). Spermatozoal motion characteristics were similar for all spermatozoal treatments after cooling at 5 degrees C. After cryopreservation, PSCH liposome-treated samples had higher percentages of motile spermatozoa than untreated samples regardless of freezing extender. Samples frozen in CO medium had higher percentages of motile spermatozoa than samples frozen in SMEY (P < 0.05; 63% in CO + PSCH and 54% in CO vs 55% in SMEY + PSCH and 48% in SMEY, respectively). In Experiment 3, spermatozoa were treated with dilauroylphosphatidylcholine (PC12) to induce the acrosome reaction. The percentages of viable cells and viable acrosome-reacted spermatozoa were higher for fresh spermatozoa than for cryopreserved spermatozoa (P < 0.05), but were not affected by PSCH liposome treatment (P > 0.05). Addition of PSCH liposomes improved recovery of motile spermatozoa after cryopreservation but did not affect the ability of spermatozoa to undergo a PC12-induced acrosome reaction. |
| Effects of phospholipase A2, free fatty acids and 2-lysolecithin on the crystallization of cholesterol in gallbladder bile Schone, A., D. Jungst, et al. (2000), Eur J Clin Invest 30(8): 715-21. Abstract: BACKGROUND: Phospholipase A2 (PLA2) and its enzymatic products free fatty acids (FFAs) and 2-lysolecithin are physiological constituents of bile. Their role in the crystallization of cholesterol in gallbladder bile of patients with cholesterol gallstones is still controversial. DESIGN: To clarify this issue we evaluated the activity of PLA2 and the concentration and pattern of FFAs in the gallbladder bile of cholesterol stone patients. We furthermore added PLA2, FFAs and 2-lysolecithin to isotropic gallbladder bile, determined the crystal observation time (COT) and counted the cholesterol crystals in a crystal growth assay for up to 21 days. RESULTS: A PLA2 activity of 1.8 +/- 1.2 U L(-1) and total FFA concentrations of 1.32 +/- 0.71 mmol L(-1) were determined. After incubation of bile for 24 h at 37 degrees C total FFAs increased to 2.72 +/- 1.29 mmol L(-1) (P<0.005). Biliary saturated and unsaturated FFAs were found in equal proportions before and after incubation, pointing to an additional presence of lipases other than PLA2. A COTof 1 day was observed in all gallbladder biles and increased to 1.7 +/- 0.5 days after addition of 5 U L(-1) of PLA2 (P<0.01). An even higher COT of 2.5 +/- 0.8 days was seen after addition of 5 mmol L(-1) of a 'biliary' mixture of FFAs (P<0.005) but the COT remained unchanged after addition of 5 mmol L(-1) of 2-lysolecithin. However, in the crystal growth assay in gallbladder bile addition of 5 U L(-1) of PLA2, of 5 mmol L(-1) of 'biliary' FFAs and of 5 mmol L(-1) of 2-lysolecithin decreased significantly the number of cholesterol crystals formed during follow-up. CONCLUSION: An elevated activity of PLA2 in gallbladder bile may counteract the formation of cholesterol crystals through increased formation of FFAs and 2-lysolecithin. However, regarding the comparatively low activity of PLA2 in gallbladder bile PLA2 seems to be of only minor pathophysiological importance in the formation of cholesterol gallstones. |
| Effects of physical exercise on sex hormone binding globulin, high density lipoprotein cholesterol, total cholesterol and triglycerides in postmenopausal women Caballero, M. J. and M. Maynar (1992), Endocr Res 18(4): 261-79. Abstract: This study was performed on 18 postmenopausal female volunteers in order to examine changes in sex hormone binding globulin (SHBG), high density lipoprotein cholesterol (HDLC), total cholesterol (TC) and serum triglyceride (TG) levels in a period of four months of moderate physical exercise. While SHBG decreased significantly (from 55.3 +/- 20.9 to 48.3 +/- 21.0 nM, P < 0.05), TG increased significantly (from 87 +/- 41.7 to 120.5 +/- 57.5 mg/dl, P < 0.001). These changes were accompanied by a significant decrease (P < 0.001) in body fat content. Other parameters such as HDL-cholesterol, TC and BMI did not change significantly. Plasma levels of SHBG were negatively correlated to serum TG both at the beginning (r = 0.492, P < 0.05) and at the end (r = 0.538, P < 0.05) of the period of moderate exercise. Also, changes in SHBG were negatively correlated with changes in BMI (r = 0.585, P < 0.05) and this could indicate that SHBG levels are more related to nutritional status than androgen/estrogen imbalance. |
| Effects of physiologically relevant pressures of helium on the structure of cholesterol-containing lipid bilayers. A neutron diffraction study Franks, N. P. and W. R. Lieb (1991), Biophys J 60(2): 498-501. Abstract: We have used neutron diffraction to study the effects of helium gas (1-210 atm) on the structure of a lipid bilayer model of neuronal plasma membranes. We have recorded diffraction patterns from hydrated multilayers of dimyristoyl lecithin and 40% (molar) cholesterol to a resolution of approximately 6.5 A and have calculated scattering amplitude density distributions as a function of pressure. We find that there are no significant changes in the scattering density profiles at 95% confidence over the range of pressures investigated, suggesting that the physiological effects of high helium pressure are unlikely to be a consequence of changes in the structures of the lipid bilayer portions of membranes. |
| Effects of phytosterol ester-enriched margarine on plasma lipoproteins in mild to moderate hypercholesterolemia are related to basal cholesterol and fat intake Mussner, M. J., K. G. Parhofer, et al. (2002), Metabolism 51(2): 189-94. Abstract: Dietary phytosterols have been reported to lower total and low-density lipoprotein (LDL) cholesterol. However, less is known about the influence of cholesterol and fat intake on the cholesterol-lowering effect of esterified phytosterols in mild to moderate hypercholesterolemia. Sixty-three healthy subjects (38 women, 25 men, 42 +/- 11 years, LDL cholesterol > 130 mg/dL) were investigated in a randomized, double-blind, placebo-controlled, cross-over study. A total of 20 g/d of a phytosterol ester-enriched margarine (1.82 g/d of phytosterols) was compared with a control margarine (0.06 g/d of phytosterols). After 3 weeks of intake, participants crossed over to the other margarine. A 3-day dietary recall was performed at the beginning and at the end of the study to assess cholesterol, fat, and energy intake. Phytosterol ester-enriched margarine significantly changed total cholesterol (-3.4%, P <.005), LDL cholesterol (-5.4%, P <.001, 144 +/- 28 v 154 +/- 26 mg/dL), high-density lipoprotein (HDL) cholesterol (+3.4%, P <.05), apolipoprotein B (-4.0%, P <.005), and LDL/HDL cholesterol ratio (-7.8%, P <.001) compared with the control margarine. In the tertiles with the highest dietary intake of cholesterol, energy, total fat, and saturated fatty acids, and with the highest baseline proportion of campesterol to cholesterol, LDL cholesterol reduction was 11.6% (P <.001), 9.5% (P =.001), 9.4% (P =.001), 8.4% (P =.005), and 6.2% (P =.014), respectively. Triglycerides, plasma viscosity, and fibrinogen concentration did not change significantly. The improvements of LDL, HDL, total cholesterol, apolipoprotein B concentrations, and LDL/HDL cholesterol ratio during the daily consumption of a phytosterol ester-enriched margarine were most marked in those subjects with a high dietary intake of cholesterol, energy, total fat, and saturated fatty acids and with high baseline cholesterol absorption. |
| Effects of plant polysaccharides on cell proliferation and cell membrane contents of sialic acid, phospholipid and cholesterol in S 180 and K 562 cells Tong, L., T. Y. Huang, et al. (1994), Zhongguo Zhong Xi Yi Jie He Za Zhi 14(8): 482-4. Abstract: The four kinds of plant polysaccharides, i.e., pachyman polysaccharides (PPS), Acanthopanax senticosus polysaccharides (ASPS), polysaccharides of tremella fuciformis (TF) and lentinan, have obviously inhibitory action against the animal tumor growth and have been applied to the treatment of cancer. The mechanism was that they could enhance the body immune function, but whether the tumor cells were killed is not clear. In this paper, the effects of the four plant polysaccharides on cell proliferation in mice sarcoma (ascitic type) S180 and human chronic myelogenous leukemia K562 cells were studied with MTT chromometry. Tt was found That TF and lentinan had no effect on both cell line, but PPS and ASPS could obviously inhibit the proliferation of them, the IC50 of PPS was 1.5mg/ml in both cell line, that of ASPS was 0.38 mg/ml (S180 cells) and 0.28mg/ml (K562 cells) respectively. This result indicated that the PPS and ASPS were able to kill the tumor cell directly. To investigate the mechanism of antitumor action of PPS and ASPS, the sialic acid (SA), phospholipid (PI) and cholesterol (Ch) contents of S180 cell membrane were examined after the PPS or ASPS application for 24 hours. No significant changes were observed for the Ch and Ch/Pl ratio, the amount of SA increased and that of PI lowered respectively (P < 0.05). The results suggested that the antitumor action of PPS and ASPS not only related to the action of enhancing the body immune function but also related to the changes of cell membrane. |
| Effects of plant stanol esters supplied in low-fat yoghurt on serum lipids and lipoproteins, non-cholesterol sterols and fat soluble antioxidant concentrations Mensink, R. P., S. Ebbing, et al. (2002), Atherosclerosis 160(1): 205-13. Abstract: Oil-based products enriched with plant stanol esters can lower low-density lipoprotein (LDL) cholesterol concentrations by 10-14%. Effectiveness of low-fat products, however, has never been evaluated, although such products fit into a healthy diet. We therefore examined the effects of plant stanol esters emulsified into low-fat yoghurt (0.7% fat) on fasting concentrations of plasma lipids and lipid-soluble antioxidants, which may also change by plant stanol consumption. Sixty non-hypercholesterolemic subjects first consumed daily three cups (3 x 150 ml) of placebo yoghurt for 3 weeks. For the next 4 weeks, 30 subjects continued with the placebo yoghurt, while the other 30 subjects received three cups of experimental yoghurt. Each cup provided 1 g of plant stanols (0.71 g sitostanol plus 0.29 g campestanol) as its fatty acid ester. LDL cholesterol (mean+/-S.D.) increased by 0.06+/-0.21 mmol/l in the placebo group, but decreased by -0.34+/-0.30 mmol/l in the experimental group. The difference in changes between the two groups of 0.40 mmol or 13.7% was highly significant (P<0.001; 95% confidence interval for the difference, (-)0.26 -(-)0.53 mmol/l). Effects were already maximal after 1 week. HDL cholesterol and triacylglycerol concentrations did not change. Total tocopherol levels increased by 1.43 micromol/mmol LDL cholesterol (14.0%, P=0.015). beta-carotene levels, however, decreased by -0.02 micromol/mmol LDL cholesterol (-14.4%, P=0.038). Decreases in absolute beta-carotene concentrations were found in all apoB-containing lipoproteins. LDL-cholesterol standardised phytofluene levels decreased by 21.4+/-25.7% (P<0.001), while other plasma carotenoid (lutein/zeaxanthin, beta-cryptoxanthin, lycopene and alpha-carotene) levels did not change significantly. We conclude that low-fat yoghurt enriched with plant stanol esters lowers within 1 week LDL cholesterol to the same extent as oil-based products. LDL-cholesterol standardised concentrations of tocopherol increased. The observed decrease in beta-carotene levels, as found in many other studies, appears not to be limited to the LDL fraction. |
| Effects of policosanols and phytosterols on lipid levels and cholesterol biosynthesis in hamsters Wang, Y. W., P. J. Jones, et al. (2003), Lipids 38(2): 165-70. Abstract: The current study was carried out to examine the effects of policosanols and phytosterols, alone and in combination, on lipid profiles, cholesterol biosynthesis, and tissue histopathological changes in hamsters. Fifty male Golden Syrian hamsters, weighing 100 to 120 g, were fed a regular rodent chow for 2 wk before being randomly assigned into 5 groups of 10 animals each fed semisynthetic diets for 4 wk. Group 1 was given a control diet that contained 0.25% cholesterol and 5% fat with a PUFA to saturated FA ratio of 0.4. Groups 2 to 5 were fed the control diet and given Octa-6 a policosanol mixture from sugar cane wax, 25 mg/kg body weight (BW), Ricewax (a policosanol mixture from rice wax with 50% being converted to the corresponding acids, 50 mg/kg BW), phytosterols (Cholestatin; 1,000 mg/kg BW), and Ricewax (50 mg/kg BW) plus phytosterols (1,000 mg/kg BW), respectively. The results showed that there was no difference between Octa-6 and Ricewax treatments in any of the lipid parameters measured, and both had similar levels of triglyceride (TG), total cholesterol (T-C), and HDL cholesterol (HDL-C) as the control. Octa-6 but not Ricewax increased (P = 0.03) non-HDL-C as compared with the control. Phytosterols reduced T-C (P < 0.0003) and HDL-C (P < 0.004) without a significant effect on TG and non-HDL-C as compared to the control. Ricewax plus phytosterols had effects similar to those with phytosterols alone. Free cholesterol synthetic rates were not different among the treatments. Policosanols or phytosterols did not show any toxic effects in liver, heart, brain, or kidney. Results suggest that, although phytosterols reduce T-C and HDL-C levels, policosanols have no significant favorable effect in changing lipid levels in hamsters. |
| Effects of polychlorinated biphenyls on cholesterol and ascorbic acid metabolism in primary cultured rat hepatocytes Nagaoka, S., H. Kamuro, et al. (1991), Biochem Pharmacol 41(8): 1259-61. Abstract: Urea formation, cell number, cellular protein content and tyrosine transaminase activity were not changed by PCB addition in cultured rat hepatocytes. These results indicate that these liver functions are similar to control levels despite the addition of PCBs. Our results show that primary cultured hepatocytes mimic partially the intact liver in relation to some responses to PCBs. In isolated hepatocytes as well as in vivo, PCBs increased in cellular ascorbic acid level, aryl hydrocarbon hydroxylase and UDP-glucuronyl transferase activities. Thus, the present results may suggest that the metabolic changes in vivo concerning ascorbic acid induced by dietary PCBs were primarily related to the direct effects of PCBs per se on liver parenchymal cells. |
| Effects of polyphenolic fraction of silymarin on lipoprotein profile in rats fed cholesterol-rich diets Skottova, N., R. Vecera, et al. (2003), Pharmacol Res 47(1): 17-26. Abstract: To study the influence of polymerised polyphenolics (PP), a fraction of silymarin (SM), on lipids and oxidant status, rats were fed high-cholesterol (1%), high-fat (10%) diets containing either lard fat (LFD) rich in saturated/monounsaturated fatty acids, or currant oil (COD) rich in polyunsaturated fatty acids. PP and SM were administered as dietary supplements (0.1-0.5-1.0%) for 3 weeks. PP (1%) decreased cholesterol (C) in VLDL (from 0.72+/-0.08 mmol l(-1) in LFD control to 0.35+/-0.07 mmol l(-1), P<0.01, and from 0.33+/-0.05 mmol l(-1) in COD control to 0.09+/-0.02 mmol l(-1), P<0.001), and increased HDL-C/VLDL-C ratio, however, without effect on the total plasma C and LDL-C. Liver C content (LFD 19.32+/-1.50 micromol g(-1), COD 18.64+/-2.13 micromol g(-1), N.S.) decreased after PP (1%) to 12.24+/-0.76 micromol g(-1), P<0.01, and 8.78+/-0.95 micromol g(-1), P<0.001, respectively. Triacylglycerols (TAG) in plasma and VLDL decreased after PP in the LFD group only, which displayed higher TAG levels than the COD group. Likewise, LFD caused a higher liver TAG content than did COD (31.16+/-3.00 micromol g(-1) versus 17.31+/-1.48 micromol g(-1), P<0.01), and PP (1%) decreased liver TAG only in rats fed LFD (19.55+/-2.43 micromol g(-1), P<0.02). Blood glutathione (GSH) increased after PP (1%) in the LFD group from 0.97+/-0.11 to 1.54+/-0.19 mmol l(-1) (P<0.05) and in the COD group from 0.58+/-0.15 to 1.23+/-0.10 mmol l(-1) (P<0.01), while liver GSH and plasma TBARS did not change. On principle, effects of PP were dose-dependent and parallel to SM. These results suggest that the polyphenolic fraction of SM positively modifies lipoprotein profile, counteracts the development of fatty liver and ameliorates an antioxidant status in circulation. |