(Circulation. 1999;99:1733-1739.)
© 1999 American Heart Association, Inc.
Basic Science Reports |
Proatherogenic and Antiatherogenic Effects of Probucol and Phytosterols in Apolipoprotein E–Deficient Mice
Possible Mechanisms of Action
From the Atherosclerosis Specialty Laboratory (M.H.M., J.J.F.) and Cardiovascular Research Laboratory (B.M.M.), Department of Pathology and Laboratory Medicine, Department of Pharmacology and Therapeutics (D.V.G.), Faculty of Pharmaceutical Sciences (B.R.), University of British Columbia and St. Paul's Hospital, Vancouver, Canada.
Correspondence to Jiri J. Frohlich, MD, #180-1081 Burrard St, Vancouver, BC, Canada V6Z 1Y6. E-mail jifr{at}unixg.ubc.ca
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Background—The effects of probucol and a phytosterol mixture (FCP-3PI) on atherosclerotic lesion formation, plasma lipoproteins, hepatic and lipoprotein lipase activities, antioxidant enzyme activities, and plasma fibrinogen were investigated in apolipoprotein E–knockout (apoE-KO) mice.
Methods and Results—Three groups of 8 mice were fed a diet containing 9% (wt/wt) fat (controls) or the foregoing diet supplemented with either 1% (wt/wt) probucol (the probucol group) or 2% (wt/wt) FCP-3PI (the FCP-3PI group) for 20 weeks. Compared with controls, atherosclerotic lesion size was 3 times greater in the probucol group, whereas it was decreased by half in the FCP-3PI group. Probucol treatment resulted in high plasma probucol concentrations, which correlated (r=0.69) with the lesion area. HDL cholesterol was reduced (>75%) in the probucol group and slightly increased (14%) in the FCP-3PI–treated group. Postheparin lipoprotein lipase (LPL) activity was significantly reduced in both treatment groups, but only FCP-3PI significantly decreased hepatic lipase activity. Plasma fibrinogen was increased 42% by probucol and decreased 19% by FCP-3PI relative to controls. Probucol significantly increased plasma glutathione reductase, glutathione peroxidase, and superoxide dismutase activities (P<0.05). In contrast to findings in apoE-KO mice, there was no probucol-induced atherosclerosis in their wild-type counterparts fed the same dose for the same period of time.
Conclusions—Antiatherogenic activity of FCP-3PI in apoE-KO mice is associated with an increase in HDL cholesterol concentration along with decreases in hepatic lipase activity and plasma fibrinogen concentrations. Proatherogenic effects of probucol may be related to increased plasma fibrinogen, decreased HDL cholesterol concentrations along with decreased LPL activity, or its direct "toxicity" due to very high plasma concentration. Our studies demonstrate that the antioxidant and cholesterol-lowering properties of probucol do not prevent atherogenesis in this particular animal model.
Key Words: hypercholesterolemia • atherosclerosis • lipoproteins • fibrinogen • antioxidants
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Apolipoprotein E–knockout (apoE-KO) mice have been used extensively to study the relation of hypercholesterolemia and lipoprotein oxidation to atherogenesis.1 2 3 4 5 6 7 Phytosterols5 6 and the antioxidant N,N'-diphenyl-1,4-phenylenediamine7 both reduced the severity of aortic atherosclerosis in apoE-KO mice, with and without reduction in plasma cholesterol concentrations, respectively. In contrast, probucol, an agent with antioxidant and cholesterol-lowering properties, paradoxically promoted atherogenesis in apoE-KO mice8 9 and LDL receptor–deficient mice.10 These findings suggest that factors other than hypercholesterolemia and decreased antioxidant status may be involved in the development of atherosclerotic plaques.
To investigate the mechanisms involved in the pathogenesis of accelerated atherogenesis in this animal model, we compared the effects of probucol with those of a phytosterol mixture, FCP-3PI. Our findings indicate a paradoxical proatherogenic effect of probucol, despite its prominent cholesterol-lowering and antioxidant properties. Increased fibrinogen concentrations, decreased HDL cholesterol concentrations, and diminished lipoprotein lipase (LPL) activity may in part account for the atherogenicity of probucol in the apoE-KO mouse model of atherogenesis.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Animals and Diets
Twenty-four 4-week-old male C57BL/6J mice homozygous for deletion of the apoE gene (apoE-KO) and 6 wild-type C57BL/6J mice were purchased from the Jackson Laboratory, Bar Harbor, Me. After a 10-day adaptation period, they were divided into 3 groups (control, probucol treated, and FCP-3PI treated) of 8 (apoE-KO) and 2 (C57BL/6J) mice each, matched for their plasma lipid concentrations and body weight. The mice were fed with PicoLab mouse diet 20 (Jamieson's Pet Food Distributor) (1) without additional supplementation (control), (2) supplemented with 1% (wt/wt) probucol (Hoechst Marion Roussel Inc; probucol treated), or (3) supplemented with 2% (wt/wt) FCP-3PI (phytosterol treated). FCP-3PI (previously named TODPM) extraction and purification and the preparation of supplemented diets have been previously described.5 The phytosterol mixture used contained 69% ß-sitosterol, 16% sitostanol, and 15% campesterol. Animals were weighed biweekly, and results are presented in Table 1
. Except for the small eruptive
skin lesions in the ear area of 1 control and 5 probucol-treated mice,
all animals looked healthy and were active during the experimental
period. The study was approved by the Animal Care Committee of the
University of British Columbia.
|
Blood Sampling
Plasma and red cells were prepared as previously
described5 and used for biochemical analyses.
Histological Examination
Sections from the aortic roots and thoracic aortas were cut and
stained with oil red O (ORO), hematoxylin and eosin, and Movat
pentachrome as previously described.5
Morphometry
Aortic root sections stained with ORO were used for morphometric
measurements as previously described.5 Briefly, using a
Quanta BioTech II digitizing system, we determined total lesion area,
external circumference of the aortic root, and total lumen area of the
aortic root sections. We calculated lesion to lumen ratio by dividing
the average lesion area by the average lumen area.
Plasma Probucol Concentrations
The concentration of probucol in the terminal plasma samples was
determined by a previously published method.9 The mean of
duplicate measurements was calculated for each animal in the
probucol-treated group.
Lipoprotein Cholesterol Concentrations
Plasma lipoprotein fractions were separated by a fast protein
liquid chromatography system.11 Briefly,
aliquots of plasma were injected into the system, and fractions
corresponding to VLDL and IDL, LDL, and HDL were collected.
Cholesterol was extracted from the pooled fractions of
VLDL/IDL, LDL, and HDL and was quantified
enzymatically.5
Plasma Lipase Activity
Aliquots of plasma (before and after heparin) were used for
measurement of lipase (total, lipoprotein, and hepatic) activity as
previously described.12 Briefly, labeled
triglyceride ([3H]triolein) was
incubated with plasma samples, and liberated fatty acids
([3H]oleate) were quantified by liquid
scintillation counting.
Plasma Fibrinogen Analysis
At the final sampling period, heparin (1.5 U/g IP) and
pentobarbital (60 mg/kg IP) were administered. Fibrinogen was measured
by the established Clauss method.
Red Cell and Plasma Antioxidant Enzyme Analyses
Red blood cells from the terminal blood samples were separated
from plasma by centrifugation and washed twice with
isotonic saline. Aliquots of plasma samples and red cells were
analyzed for the activity of glutathione peroxidase,
glutathione reductase, superoxide dismutase, and catalase as previously
described.13
Statistical Analyses
Results were analyzed by 1-way ANOVA followed by
application of the Tukey test to assess the significance of specific
intergroup differences with SPSS software. Data are expressed as
mean±SD.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Histological Findings
Sections from aortic roots from all animals showed ORO-positive atherosclerotic lesions by light microscopic examination. However, the extent and severity of the lesions varied markedly among the 3 groups of mice. The probucol-treated animals had the worst lesions with regard to size, severity, and lipid enrichment. Sections from the FCP-3PI–treated animals had lesions with the least volume and apparently less complexity than either the control or the probucol-treated groups. Numerous cholesterol clefts were observed in sections from the probucol-treated and control groups but not in the sections from the FCP-3PI–treated animals. Differences in the extent, severity, and complexity of the lesions from probucol and control groups were more readily appreciated when sections were stained with Movat pentachrome. Figure 1
compares the lesions in representative sections stained
with ORO and Movat staining of aortic root sections cut from similar
anatomic locations in individual mice from the FCP-3PI–treated (A and
B), control (C and D), and probucol-treated (E and F) groups. Figure 1E
shows an increased amount of extracellular matrix in the presence of
sheaths of apparently proliferative smooth muscle cells, numerous foam
cells, and cholesterol crystals indicative of mature and
complex lesions in the probucol-treated group. These characteristic
features of atherosclerotic lesions are present to a lesser extent
in Figure 1C (the control group) and are much less evident in Figure 1A
(the FCP-3PI–treated group). Figure 1E also includes evidence of an
atherosclerotic aortic aneurysm (arrow). Similarly, as shown in
Figure 2, thoracic aortas from the
probucol-treated animals showed severe atherosclerotic lesions by
various histochemical staining methods (G, H, and I). As evident in a
Movat-stained section (Figure 2H, straight arrow) from a
representative aorta of the probucol-treated group, all
elastic laminae were disrupted, rendering the aorta prone to the
development of an atherosclerotic aneurysm and, potentially, to
through-and-through rupture of the vessel wall. However, such prominent
lesions in thoracic aortas were not observed frequently. In concordance
with findings in the aortic roots, the control group also had advanced
lesions in their thoracic aortas (Figure 2D, 2E, and 2F). A
normal-appearing aorta from an FCP-3PI–treated animal with intact
intimal and medial elastic laminae and normal-appearing smooth muscle
cells and endothelium is also shown (Figure 2A, 2B, and 2C). In contrast to apoE-KO mice, none of their wild-type counterparts
had any evidence of atherosclerotic lesions in their aortic roots.
|
|
Aortic Morphometry
Probucol treatment caused a 175% increase (relative to the
untreated group) in average lesional area (in square millimeters) of
aortic roots, whereas FCP-3PI treatment caused a 50% decrease
(relative to the untreated group). These changes paralleled other
morphometric measurements such as circumference of the aortic roots (in
millimeters) and lesion-to-lumen ratios. Thus, as summarized in Table 2, the greater the lesional area, the
greater the circumference and the higher the lesion-to-lumen ratio. As
such, both severe intimal disease and remodeling were evident.
|
Plasma Probucol Concentrations
The mean concentration of probucol in plasma was 404.6±92.8
µg/mL (n=8). Regression analysis showed a strong
(r=0.69, n=8) relationship between the plasma concentrations
of probucol and the size of aortic lesions in the probucol-treated
mice.
Cholesterol Concentrations of Plasma Lipoprotein
Fractions
Both probucol and FCP-3PI treatments significantly reduced plasma
VLDL/IDL cholesterol concentrations. However, this
reduction was greater in the probucol-treated group (78% versus 37%
decrease by probucol and FCP-3PI, respectively, relative to controls).
Similarly, the LDL cholesterol–lowering effects of
probucol were greater than those of FCP-3PI (50% versus 20%,
respectively). On the other hand, HDL cholesterol
concentrations were markedly reduced (>75% decrease) by probucol
treatment and slightly increased (by 
14%) in the FCP-3PI–treated
animals compared with controls. Mean plasma lipoprotein
cholesterol concentrations are depicted in Figure 3. In wild-type C57BL/6J animals, plasma
total cholesterol concentrations remained unchanged with
phytosterol treatment, but they were reduced by >80% in the
probucol-treated animals.
|
Plasma Lipolytic Activity
Intraperitoneal administration of heparin
markedly increased total plasma lipase activity (30 versus 365 mU [the
control group], 30 versus 248 mU [FCP-3PI–treated group], and 37
versus 250 mU [probucol-treated group], mean values, n=8). Table 3 shows significant reductions in
postheparin total, lipoprotein, and hepatic lipase
activities in response to both probucol (except hepatic lipase) and
FCP-3PI treatments. Probucol and FCP-3PI treatments caused 40% and
31% decreases, respectively, in the average LPL activity compared with
the control group (P<0.05). Compared with controls, hepatic
lipase activity was significantly reduced by 35% in the
FCP-3PI–treated group only.
|
Plasma Fibrinogen Concentrations
Fibrinogen concentrations differed between the 2 treatment groups
and as compared with the control group. Probucol treatment caused a
significant increase (42%) in fibrinogen concentrations (2.6±0.7
versus 3.7±0.7 g/L; n=8; P<0.01), whereas FCP-3PI
treatment reduced fibrinogen by 19% (2.6±0.7 versus 2.1±0.2 g/L;
n=8) compared with controls.
Antioxidant Enzyme Activities
Table 4 summarizes the effect of
each treatment on the activity of antioxidant enzymes in red blood
cells and plasma. Both treatment regimens, particularly probucol,
altered the activity of plasma antioxidant enzymes. Among the
erythrocyte enzymes examined, glutathione reductase activity increased
in both treatment regimens. The extent of the increment in erythrocyte
glutathione reductase resulting for probucol was approximately twice
that in the FCP-3PI–treated group (24% versus 14%). Similarly, the
effect of probucol on increasing plasma glutathione peroxidase and
superoxide dismutase activities was 5 times greater than that of
FCP-3PI. Probucol and FCP-3PI had opposite effects on the activity of
plasma glutathione reductase.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Although both probucol and FCP-3PI reduced VLDL and LDL cholesterol, the extent of this effect was more marked with probucol treatment. HDL cholesterol was dichotomously affected by probucol and FCP-3PI. The mechanism of the cholesterol-lowering effect of probucol is poorly understood.14 Phytosterols, however, are known to inhibit cholesterol absorption.15
Probucol is proatherogenic in apoE-KO mice and LDL receptor-deficient mice.8 9 10 One possible explanation is the well-known HDL cholesterol–lowering effect of probucol in various species, including transgenic mice.9 10 16 17 18 Because hepatic lipase–deficient mice show increased HDL production,19 the FCP-3PI treatment–induced slight (14%) increase in HDL cholesterol concentrations is possibly related to the significant decrease in hepatic lipase activity. The observed reductions in both hepatic and LPL activities by FCP-3PI treatment may prevent formation of small atherogenic ß-VLDL particles19 and may also decrease their uptake by the LDL receptor–related protein.20
In addition to decreases in HDL cholesterol concentrations, probucol also alters the size and quality of HDL particles.21 Although the mechanisms by which probucol influences the metabolism of HDL particles are not clear, changes in LPL and cholesteryl ester transfer protein (CETP) may play a role. Probucol treatment in humans is associated with an increase in CETP mass, which was correlated with the concomitant decrease in HDL cholesterol concentrations.22 Consistent with our findings, probucol caused a significant reduction in postheparin LPL activity and HDL cholesterol concentrations in patients with moderate hypercholesterolemia and in rats.23 24 However, the HDL cholesterol–lowering action of probucol in animals (mouse and rat) without CETP25 26 suggests that this effect of probucol is independent of CETP activity.
Because probucol treatment was not proatherogenic in wild-type mice (despite its HDL-lowering effects), it seems less likely that it is the major mechanism of its proatherogenic activity in the apoE-KO mouse model.9 Moreover, several studies27 28 29 30 have shown beneficial effects of probucol on atherosclerosis and xanthomatosis in both humans and animals.
Although it is not clear whether the increased plasma fibrinogen is a marker of disease or a cause or both, the increased plasma fibrinogen may be considered a possible causal factor for the proatherogenic effect of probucol in apoE-KO mice. Fibrinogen concentrations have been significantly correlated with the likelihood of atherosclerotic cardiac events.31 32 In rabbits, probucol showed an antiatherogenic effect in association with a reduction in fibrinogen concentrations (but no effect on cholesterol levels).33 In the present study, FCP-3PI–treated animals had lower fibrinogen concentrations and fewer (and less severe) atherosclerotic lesions than either the control or probucol-treated groups. The mechanisms underlying changes in plasma fibrinogen levels caused by probucol and phytosterols remain to be studied.
We have shown herein that treatment with probucol is accompanied by an increase in the activity of several endogenous antioxidant enzymes. However, foam cell formation was increased. This suggests that the antioxidant effects of probucol alone are not sufficient to prevent lesion development.
We have documented that foam cell formation is increased in probucol-treated mice but significantly reduced in FCP-3PI–treated animals. It may be speculated that modification of ß-VLDL (a major substrate for foam cell formation) by phytosterols may result in its decreased uptake by macrophages, thereby delaying foam cell formation and plaque development. The opposite may occur in probucol-treated mice. Histological examination revealed many cholesterol clefts in the lesions from the probucol-treated animals; these lesions also contained numerous foam cells and a substantial amount of extracellular matrix, indicating their greater maturity and complexity compared with those from either the control or the FCP-3PI–treated mice. The fact that there is no evidence of probucol-induced atherosclerotic lesions in wild-type mice34 35 suggests specific intracellular effects of probucol10 in apoE-KO mice and LDL receptor-deficient mice but not in their wild-type counterparts.
Similar to a recently published study in LDL receptor–deficient
mice,10 our data indicate a correlation
(r=0.69) between the extent of atherosclerotic lesions in
the aortic roots and the plasma concentration of probucol. Thus,
proatherogenic effects of probucol appear to depend on the dose and
duration of the treatment. The average plasma probucol concentration in
our study was 405 µg/mL (after 20 weeks of consumption of 1% wt/wt
probucol), whereas it was 56 µg/mL in a previous study in which male
apoE-KO mice consumed 0.5% (wt/wt) probucol for 3
months.9 Similarly, the mean lesion size was greater
in the present study than in the aforementioned
study.9 Probucol concentrations in the present study
were also 4 times greater than those in Watanabe heritable
hyperlipidemic rabbits administered the same dose (1%
wt/wt) of probucol for 20 months.30 Plasma probucol
concentrations observed in the present study were comparable to
those reported in Watanabe rabbits treated with 1% probucol for 6
months.36 In another study, male LDL receptor–deficient
mice also had very high plasma probucol concentrations (497
µmol/L, 260 µg/mL) after consumption of 0.5% (wt/wt)
probucol.10 Given the fact that apoE-KO mice are severely
hypercholesterolemic, our goal was to achieve greater
lipid lowering through higher plasma probucol concentration than that
usually attained in humans. Therefore, on the basis of previous
studies,9 17 30 34 35 36 37 38 39 40 41 we estimated that 1% (wt/wt)
probucol would result in a plasma concentration twice that seen in
humans treated with probucol at a dose of 1 g/d. By the end of the
study, plasma probucol concentration was higher than expected. Probucol
is a strongly lipophilic agent, and thus it accumulates in lipoprotein
particles36 ; it is also deposited into fat-containing
tissues. The half-life of probucol in plasma depends on the rate of
clearance of plasma lipoproteins. Mice lacking apoE have a substantial
delay in the metabolism of lipoproteins, particularly VLDL.
This delay may significantly increase the elimination half-life of
probucol. Another factor that could explain the high plasma
concentration of probucol concerns the loss of virtually all omental
fat in probucol-treated mice, this being the major site of tissue
sequestration of probucol. Dietary fat may increase the absorption of
probucol; thus, 9% (wt/wt) dietary fat in the present study may
also contribute to the high plasma probucol concentration and its
proatherogenic effects.
In conclusion, there is no report of a proatherogenic effect of probucol (from 0.2% to 2% wt/wt of diets or up to 800 mg · kg-1 · d-1 by stomach tube) in other strains of mouse. Additional experiments using treatment with much lower doses of probucol in apoE-KO mice will elucidate whether the proatherogenic effect of the treatment is related to drug toxicity. Our data suggest that increased plasma antioxidant activity alone does not result in decreased foam cell formation, at least in the animal model studied.
|
Acknowledgments |
|---|
This study was supported by a grant from Technology BC and Forbes Medi-Tech Inc, Vancouver, British Columbia, Canada. The authors are grateful to Professor Daniel Steinberg, University of California at San Diego, for his assistance in measuring probucol concentrations. Technical help from Karen Andersen from the Hematology Laboratory and the support of Dr Haydn Pritchard, Dr Alex Magil, Dr Min Li, Lida Adler, and Amir F. Ayyobi at St. Paul's Hospital are also greatly appreciated. The authors are also grateful to Dr Egon Novak, Forbes Medi-Tech Inc, Vancouver, BC, for his valuable suggestions.
Received July 2, 1998; revision received November 9, 1998; accepted November 18, 1998.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Plump AS, Smith JD, Hayek T, Aalto-Setala K, Walsh A, Verstuyft JG, Rubin EM, Breslow JL. Severe hypercholesterolemia and atherosclerosis in apolipoprotein E-deficient mice created by homologous recombination in ES cells. Cell. 1992;71:343–353.[Medline] [Order article via Infotrieve]
2.
Zhang SH, Reddick RL, Piedrahita JA, Maeda N.
Spontaneous hypercholesterolemia and
arterial lesions in mice lacking apolipoprotein E.
Science. 1992;258:468–471.
3.
Palinski W, Ord VA, Plump AS, Breslow L, Steinberg D,
Witztum J. Apo E-deficient mice are a model of lipoprotein oxidation in
atherogenesis: demonstration of oxidation-specific epitopes in lesions
and high titers of autoantibodies to malondialdehyde-lysine in serum.
Arterioscler Thromb. 1994;14:605–616.
4.
Maor I, Hayek T, Coleman R, Aviram M. Plasma LDL
oxidation leads to its aggregation in the atherosclerotic
apolipoprotein E-deficient mice. Arterioscler Thromb Vasc
Biol. 1997;17:2995–3005.
5.
Moghadasian MH, McManus BM, Pritchard PH, Frohlich JJ.
"Tall oil"-derived phytosterol mixture reduces
atherosclerosis in apo E-deficient mice.
Arterioscler Thromb Vasc Biol. 1997;17:119–126.
6. Moghadasian MH, McManus BM, Frohlich JJ. Phytosterols prevent atherosclerosis in apo E-deficient mice. Can J Cardiol. 1997;13:81B. Abstract.
7.
Tangirala RK, Casanada F, Miller E, Witztum JL,
Steinberg D, Palinski W. Effects of the antioxidant
N,N'-diphenyl 1,4-phenylenediamine (DPPD) on
atherosclerosis in apo E-deficient mice.
Arterioscler Thromb Vasc Biol. 1995;15:1625–1630.
8. Moghadasian MH, McManus BM, Frohlich JJ. Atherogenicity of probucol in apo E-deficient mice. 4th International Symposium on Multiple Risk Factors in Cardiovascular Disease: Strategies of Prevention of Coronary Heart Disease, Cardiac Failure, and Stroke. Washington, DC; April 1997:31. Abstract.
9. Zhang SH, Reddick RL, Avdievich E, Surles LK, Jones RG, Reynolds JB, Quarfordt SH, Maeda N. Paradoxical enhancement of atherosclerosis by probucol treatment in apolipoprotein E-deficient mice. J Clin Invest. 1997;99:2858–2866.[Medline] [Order article via Infotrieve]
10.
Bird DA, Tangirala RK, Fruebis J, Steinberg D, Witztum
JL, Palinski W. Effects of probucol on LDL oxidation and
atherosclerosis in LDL receptor-deficient mice. J
Lipid Res. 1998;39:1079–1090.
11. van Ree JH, van den Broek WJAA, Dahlmans VEH, Groot PHE, Vidgeon-Hart M, Frants RR, Wieringa B, Havekes LM, Hofker MH. Diet-induced hypercholesterolemia and atherosclerosis in heterozygous apolipoprotein E-deficient mice. Atherosclerosis. 1994;111:25–37.[Medline] [Order article via Infotrieve]
12. Galan X, Llobera M, Ramirez I. Lipoprotein lipase and hepatic lipase in Wistar and Sprague Dawley rat tissues: differences in the effects of gender and fasting. Lipids. 1994;29:333–336.[Medline] [Order article via Infotrieve]
13. Wohaieb SA, Godin DV. Starvation-related alterations in free radical tissue defense mechanisms in rats. Diabetes. 1987;36:169–173.[Abstract]
14. Davignon J. Probucol. Handbook Exp Pharmacol. 1994;109:429–469.
15. Ikeda I, Tanaka K, Sugano M, Vahouny GV, Gallo LL. Inhibition of cholesterol absorption in rats by plant sterols. J Lipid Res. 1988;29:1573–1582.[Abstract]
16. Walldius G, Erikson U, Olsson AG, Bergstand L, Hadell K, Johanson J, Kaijser L, Lassvik C, Molgaard J, Nilsson S, Schafer-Elinder L, Stenport G, Holme I. The effect of probucol on femoral atherosclerosis: the Probucol Quantitative Regression Swedish Trial (PQRST). Am J Cardiol. 1994;74:875–883.[Medline] [Order article via Infotrieve]
17. Sasahara M, Raines EW, Chait A, Carew TE, Steinberg D, Wahi P, Ross R. Inhibition of hypercholesterolemia-induced atherosclerosis in the nonhuman primate by probucol. J Clin Invest. 1994;94:155–164.
18.
Tardif JC, Cote G, Lesperance J, Bourassa M, Lambert J,
Doucet S, Bilodeau L, Nattel S, Guise PD. Probucol and multivitamins in
the prevention of restenosis after coronary
angioplasty. N Engl J Med. 1997;337:365–372.
19.
Mexdour H, Jones R, Dengremont C, Castrol G, Maeda N.
Hepatic lipase deficiency increases plasma cholesterol but
reduces susceptibility to atherosclerosis in
apolipoprotein E-deficient mice. J Biol Chem. 1997;272:13570–13575.
20.
Kounnas MZ, Chappell DA, Wong H, Argaves WS, Strickland
DK. The cellular internalization and degradation of hepatic lipase is
mediated by low density lipoprotein receptor-related protein and
requires cell surface proteoglycans. J Biol Chem. 1995;270:9307–9312.
21. Sirtori CR, Sirtori M, Calaberisi L, Franceschini G. Changes in high-density lipoprotein subfraction distribution and increased cholesteryl ester transfer after probucol. Am J Cardiol. 1988;52:73B–76B.
22.
McPherson R, Hogue M, Milne RW, Tall AR, Marcel YL.
Increase in plasma cholesteryl ester transfer protein during probucol
treatment: relation to changes in high density lipoprotein composition.
Arterioscler Thromb. 1991;11:476–481.
23. Kagami A, Ishikawa T, Tada N, Sakamoto T, Mochizuki K, Nagano M, Moriguchi EH, Manabe M. Effects of probucol and pravastatin on plasma lipids, activities of post heparin lipoprotein lipase, and lecithin cholesterol acyltransferase and apo A-I containing lipoproteins with and without apo A-II in patients with moderate hypercholesterolemia. Clin Biochem. 1993;26:101–107.[Medline] [Order article via Infotrieve]
24. Strandberg T, Kuusi T, Tilvis R, Miettinen T. Effects of probucol on cholesterol synthesis, plasma lipoproteins and activities of lipoprotein and hepatic lipase in the rat. Atherosclerosis. 1981;40:193–201.[Medline] [Order article via Infotrieve]
25. Paigen B, Plump AS, Rubin EM. The mouse as a model for human cardiovascular disease and hyperlipidemia. Curr Opin Lipidol. 1994;5:258–264.[Medline] [Order article via Infotrieve]
26. Oschry Y, Eisenberg S. Rat plasma lipoproteins: reevaluation of a lipoprotein system in an animal devoid of cholesteryl ester transfer activity. J Lipid Res. 1982;23:1099–1106.[Abstract]
27. Kita T, Nagano Y, Yokode M, Ishii K, Kume N, Narumiya S, Kawai C. Prevention of atherosclerotic progression in Watanabe rabbits by probucol. Am J Cardiol. 1988;62:13B–19B.[Medline] [Order article via Infotrieve]
28. Davignon J, Nestruck AC, Alaupovic P, Bouthiller D. Severe hypoalphalipoproteinemia induced by a combination of probucol and clofibrate. In: Angel A, Frohlich J, eds. Lipoprotein Deficiency Syndromes. New York, NY: Plenum Press; 1986:111–125.
29. Yamamoto A, Matsuzawa Y, Yokoyama S, Funahashi T, Yamamura T, Kishino B. Effects of probucol on xanthomata regression in familial hypercholesterolemia. Am J Cardiol. 1986;57:29H–35H.[Medline] [Order article via Infotrieve]
30.
Carew TE, Schwenke DC, Steinberg D. Antiatherogenic
effects of probucol unrelated to its
hypercholesterolemic effect: evidence that antioxidants
in vivo can selectively inhibit low density lipoprotein degradation in
macrophage-rich fatty streaks and slow the progression of
atherosclerosis in the Watanabe heritable
hyperlipidemic rabbit. Proc Natl Acad Sci
U S A. 1987;84:7725–7729.
31. Sato S, Kobayashi T, Iida M, Naito Y, Kiyama M, Kitamura A, Iso H, Komachi Y. A case-reference study on plasma fibrinogen concentrations and coronary atherosclerosis. Jpn J Epidemiol. 1996;6:81–86.
32.
Toss H, Lindahl B, Siegbahn A, Wallentin L. Prognostic
influence of increased fibrinogen and C-reactive protein levels in
unstable coronary artery disease. Circulation. 1997;96:4204–4210.
33. Mori Y, Wada H, Nagano Y, Deguchi K, Kita T, Shirakawa S. Hypercoagulable state in the Watanabe heritable hyperlipidemic rabbit, an animal model for the progression of atherosclerosis: effect of probucol on coagulation. Thromb Haemost. 1989;61:140–143.[Medline] [Order article via Infotrieve]
34.
Hayek T, Chajek-Shaul T, Walsh A, Azrolan N, Breslow J.
Probucol decreases apolipoprotein A-I transport rate and increases high
density lipoprotein cholesteryl ester fractional catabolic rate in
control and human apolipoprotein A-I transgenic mice.
Arterioscler Thromb. 1991;11:1295–1302.
35. Yoshida T, Yoshika K, Sakane N, Umekawa T, Kondo M. Probucol prevents the progression of fatty liver in MSG obese mice. Exp Clin Endocrinol. 1995;103:119–122.
36.
Kita T, Nagano Y, Yokode M, Ishii K, Kume N, Ooshima A.
Probucol prevents the progression of atherosclerosis in
Watanabe heritable hyperlipidemic rabbits, an animal
model for familial hypercholesterolemia.
Proc Natl Acad Sci U S A. 1987;84:5928–5931.
37. Naruszewicz M, Carew TE, Pittman RC, Witztum JL, Steinberg D. A novel mechanism by which probucol lowers low density lipoprotein levels demonstrated in the LDL receptor-deficient rabbit. J Lipid Res. 1984;25:1206–1213.[Abstract]
38. Nagano Y, Nakamura T, Matsuzawa Y, Cho M, Ueda Y, Kita T. Probucol and atherosclerosis in Watanabe heritable hyperlipidemic rabbit: long-term antiatherogenic effect and effects on established plaques. Atherosclerosis. 1992;92:131–140.[Medline] [Order article via Infotrieve]
39. Gebhard RL, Prigge WF, Andreini JP, Freeman ML. Effects of probucol on blood cholesterol and basal and lovastatin-induced 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in mice. J Lab Clin Med. 1991;117:299–304.[Medline] [Order article via Infotrieve]
40. Stein Y, Stein O, Delplanque B, Fesmire JD, Lee DM, Alaupovic P. Lack of effect of probucol on atheroma formation in cholesterol-fed rabbits kept at comparable plasma cholesterol levels. Atherosclerosis. 1989;75:145–155.[Medline] [Order article via Infotrieve]
41. Baker SG, Joffe BI, Mendelsohn D, Seftel HC. Treatment of homozygous familial hypercholesterolemia with probucol. S Afr Med J. 1982;62:7–11.[Medline] [Order article via Infotrieve]
This article has been cited by other articles:
 |
|
 |
|
  G. Silbernagel, G. Fauler, W. Renner, E. M. Landl, M. M. Hoffmann, B. R. Winkelmann, B. O. Boehm, and W. Marz The relationships of cholesterol metabolism and plasma plant sterols with the severity of coronary artery disease J. Lipid Res., February 1, 2009; 50(2): 334 - 341. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Helske, T. Miettinen, H. Gylling, M. Mayranpaa, J. Lommi, H. Turto, K. Werkkala, M. Kupari, and P. T. Kovanen Accumulation of cholesterol precursors and plant sterols in human stenotic aortic valves J. Lipid Res., July 1, 2008; 49(7): 1511 - 1518. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. Weingartner, D. Lutjohann, S. Ji, N. Weisshoff, F. List, T. Sudhop, K. von Bergmann, K. Gertz, J. Konig, H.-J. Schafers, et al. Vascular effects of diet supplementation with plant sterols. J. Am. Coll. Cardiol., April 22, 2008; 51(16): 1553 - 1561. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. A. Othman, M. Suh, G. Fischer, N. Azordegan, N. Riediger, K. Le, D. S. Jassal, and M. H. Moghadasian A comparison of the effects of fish oil and flaxseed oil on cardiac allograft chronic rejection in rats Am J Physiol Heart Circ Physiol, March 1, 2008; 294(3): H1452 - H1458. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Chen, L. Steinhauer, J. Hammerlindl, W. Keller, and J. Zou Biosynthesis of Phytosterol Esters: Identification of a Sterol O-Acyltransferase in Arabidopsis Plant Physiology, November 1, 2007; 145(3): 974 - 984. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. J. Wu, N. Di Girolamo, K. Beck, C. G. Hanratty, K. Choy, J. Y. Hou, M. R. Ward, and R. Stocker Probucol [4,4'-[(1-Methylethylidene)bis(thio)]bis-[2,6-bis(1,1-dimethylethyl)phenol]] Inhibits Compensatory Remodeling and Promotes Lumen Loss Associated with Atherosclerosis in Apolipoprotein E-Deficient Mice J. Pharmacol. Exp. Ther., May 1, 2007; 321(2): 477 - 484. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Nashed, B. Yeganeh, K. T. HayGlass, and M. H. Moghadasian Antiatherogenic Effects of Dietary Plant Sterols Are Associated with Inhibition of Proinflammatory Cytokine Production in Apo E-KO Mice J. Nutr., October 1, 2005; 135(10): 2438 - 2444. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. R. Wilund, L. Yu, F. Xu, G. L. Vega, S. M. Grundy, J. C. Cohen, and H. H. Hobbs No Association Between Plasma Levels of Plant Sterols and Atherosclerosis in Mice and Men Arterioscler. Thromb. Vasc. Biol., December 1, 2004; 24(12): 2326 - 2332. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Stocker and J. F. Keaney Jr. Role of Oxidative Modifications in Atherosclerosis Physiol Rev, October 1, 2004; 84(4): 1381 - 1478. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. M. Clifton, M. Noakes, D. Ross, A. Fassoulakis, M. Cehun, and P. Nestel High dietary intake of phytosterol esters decreases carotenoids and increases plasma plant sterol levels with no additional cholesterol lowering J. Lipid Res., August 1, 2004; 45(8): 1493 - 1499. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Waddington, I. B Puddey, and K. D Croft Red wine polyphenolic compounds inhibit atherosclerosis in apolipoprotein E-deficient mice independently of effects on lipid peroxidation Am. J. Clinical Nutrition, January 1, 2004; 79(1): 54 - 61. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. B. Katan, S. M. Grundy, P. Jones, M. Law, T. Miettinen, R. Paoletti, and Stresa Workshop Participants Efficacy and Safety of Plant Stanols and Sterols in the Management of Blood Cholesterol Levels Mayo Clin. Proc., August 1, 2003; 78(8): 965 - 978. [Abstract] [PDF]
|
|
|
|
|
|
L. Li, E. W. Lee, H. Ji, and Z. Zukowska Neuropeptide Y-Induced Acceleration of Postangioplasty Occlusion of Rat Carotid Artery Arterioscler. Thromb. Vasc. Biol., July 1, 2003; 23(7): 1204 - 1210. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Sundell, P. K. Somers, C. Q. Meng, L. K. Hoong, K.-L. Suen, R. R. Hill, L. K. Landers, A. Chapman, D. Butteiger, M. Jones, et al. AGI-1067: A Multifunctional Phenolic Antioxidant, Lipid Modulator, Anti-Inflammatory and Antiatherosclerotic Agent J. Pharmacol. Exp. Ther., June 1, 2003; 305(3): 1116 - 1123. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Gervais, S. Pons, A. Nicoletti, C. Cosson, J.-F. Giudicelli, and C. Richer Fluvastatin Prevents Renal Dysfunction and Vascular NO Deficit in Apolipoprotein E-Deficient Mice Arterioscler. Thromb. Vasc. Biol., February 1, 2003; 23(2): 183 - 189. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. F. Bentzon, G. Pasterkamp, and E. Falk Expansive Remodeling Is a Response of the Plaque-Related Vessel Wall in Aortic Roots of ApoE-Deficient Mice: An Experiment of Nature Arterioscler. Thromb. Vasc. Biol., February 1, 2003; 23(2): 257 - 262. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Violi, F. Micheletta, and L. Iuliano Antioxidants and atherosclerosis Eur. Heart J. Suppl., March 1, 2002; 4(suppl_B): B17 - B21. [Abstract] [PDF]
|
|
|
|
 |
|
 M. H. MOGHADASIAN, B. M. McMANUS, L. B. NGUYEN, S. SHEFER, M. NADJI, D. V. GODIN, T. J. GREEN, J. HILL, Y. YANG, C. H. SCUDAMORE, et al. Pathophysiology of apolipoprotein E deficiency in mice: relevance to apo E-related disorders in humans FASEB J, December 1, 2001; 15(14): 2623 - 2630. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. K. Witting, K. Pettersson, J. Letters, and R. Stocker Site-Specific Antiatherogenic Effect of Probucol in Apolipoprotein E-Deficient Mice Arterioscler. Thromb. Vasc. Biol., August 1, 2000; 20 (8): e26 - e33. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||