This Article Abstract Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hasler-Rapacz, J. Articles by Rapacz, J. Search for Related Content PubMed PubMed Citation Articles by Hasler-Rapacz, J. Articles by Rapacz, J. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CHOLESTEROL

(Arteriosclerosis, Thrombosis, and Vascular Biology. 1996;16:137-143.)
© 1996 American Heart Association, Inc.

Articles

Effects of Simvastatin on Plasma Lipids and Apolipoproteins in Familial Hypercholesterolemic Swine

Judith Hasler-Rapacz; Herman J. Kempen; Hans M.G. Princen; Bhalchandra J. Kudchodkar; Andras Lacko; Jan Rapacz

From the Department of Genetics and Department of Meat & Animal Sciences, University of Wisconsin, Madison (J.H.-R., J.R.); F. Hoffmann-LaRoche Ltd, Basel, Switzerland (H.J.K.); TNO-PG, The Gaubius Laboratory, Leiden, the Netherlands (H.M.G.P.); and the Department of Biochemistry and Molecular Biology, University of North Texas Health Sciences Center, Fort Worth (B.J.K., A.L.).

Correspondence to Jan Rapacz, PhD, Immunogenetics Laboratory, University of Wisconsin-Madison, 666 Animal Sciences Bldg, 1675 Observatory Dr, Madison, WI 53706-1284. E-mail rapacz@calshp.cals.wisc.edu.

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Abstract Familial hypercholesterolemia (FHC) in swine, which resembles human familial combined hyperlipidemia, is a complex lipid and lipoprotein disorder associated with the development of severe coronary lesions similar to those occurring in advanced human coronary disease. The disorder is characterized by elevated plasma total cholesterol (TC), triglycerides (TG), LDL-cholesterol (LDL-C), apolipoproteins (apo) B, C-III, and E, and by decreased levels of HDL-cholesterol (HDL-C), apoA-I, and lecithin:cholesterol acyltransferase (LCAT) activity. A dose-response study with simvastatin, a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, was conducted in four treatment groups of FHC animals, exhibiting TC250 mg/dL. The animals were fed 0, 80, 200, or 400 mg simvastatin daily for 3 weeks. The measured serum parameters included the levels of TC, VLDL-C, LDL-C, HDL-C, TG, lathosterol, apoA-I, B, C-III, and E, as well as LCAT activity. Simvastatin at 200 mg/d significantly decreased the levels of TC (-25%), LDL-C (-27%), lathosterol (-40%), apoB (-22%), apoC-III (-37%), and apoE (-24%) and modestly decreased the levels of HDL-C (-12%) and apoA-I (-11%) (percent relative to the average pretreatment and posttreatment baseline values) but did not affect the levels of TG, VLDL-C, the lathosterol/TC ratio, or LCAT activity. The levels of TC, LDL-C, apoB, and E were also lowered by simvastatin at 80 or 400 mg/d, but to a lesser extent than at 200 mg/d, while the other parameters were not influenced at these doses. The simvastatin-induced decreases of LDL-C, HDL-C, and apoA-I, B, C-III, and E were significantly correlated among each other. These results show that the trend of responses in TC, LDL-C, apoB, apoC-III, and apoE to simvastatin in the FHC swine is similar to that observed in humans, although the drug is less potent and efficacious in swine, while the results are different from those in humans with regard to the remaining parameters.

Key Words: swine • simvastatin • animal model • familial hypercholesterolemia • apolipoproteins

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
The cholesterol-lowering effect of the statins, inhibitors of HMG-CoA reductase, has been documented extensively in various patient populations with different forms of hyperlipidemia.^{1 2 3 4 5} These studies concur in that the statins are able to lower LDL-C maximally by about 40%; the half-maximal effect is obtained at a dose of 5 to 10 mg/d and the maximal effect at 40 to 80 mg/d. In parallel, the levels of TG and VLDL-C also drop^{4 5 6} and that of HDL-C increases.^{1 2 3 4 5 6}

However, responses to statin in various laboratory animals were variable, with no or only partial similarities to humans. In the hamster, for example, LDL-C can be lowered by >75% by lovastatin without evidence of reaching a plateau,^{7 8} concomitant with a drop in HDL-C and a rise in TG^{7 9} and VLDL-C.^{7 8} Lovastatin lowered LDL-C in normal and Watanabe heritable hyperlipidemic rabbits by 90% and 43%, respectively.⁷ In other rodents, the statins did not affect plasma cholesterol at all, even at very high doses (500 mg/kg).¹⁰ In the dog, lovastatin lowered both LDL-C and HDL-C,¹¹ whereas in the miniature pig, LDL-C and apoB were significantly decreased while HDL-C, TC, and VLDL-TG were not significantly affected¹² ; however, only one dose of lovastatin was used in the latter two studies.

FHC in swine shows phenotypic heterogeneity with TC variations from 130 to 490 mg/dL at 4 months of age and appears to be polygenic in nature.^{13 14 15} Unlike familial hypercholesterolemia in humans,¹⁶ in swine the FHC phenotype is not expressed at birth and animals show highly intraindividual variations until 3 to 4 months of age, at which time two of three dyslipidemia phenotypes can be identified.¹⁴ Genetic studies led to the isolation of the first monogenic cholesterol subphenotype with moderate hypercholesterolemia, TC, 223±24.7 mg/dL, exhibiting the recessive mode of inheritance, designated FHC-r.¹⁵ Animals with TC in excess of 280 mg/dL at 4 months of age express a cholesterol phenotype that is associated with advanced coronary artery disease,^{14 17 18} and is more variable and complex than the moderate phenotype. Preliminary segregation analysis of the high-cholesterol phenotype suggests the codominant mode of inheritance, temporarily designated FHC-D.¹⁴

The FHC-D phenotype shows elevated concentrations of plasma lipids (TC, LDL-C, TG), apolipoproteins B, C-III, and E, and reduced levels of HDL-C and apoA-I.^{14 19} Plasma from FHC animals is characterized by cholesterol-ester–enriched buoyant LDL, d = 1.021 to 1.043 g/mL,²⁰ and dense LDL in d>1.063 g/mL.¹³ In addition, the FHC LDL shows defective binding to the LDL receptor²¹ and delayed plasma clearance²² that seemed to be independent of the LDL receptor.²³

The primary objective of this study was to investigate the effect of simvastatin on the major plasma lipid and apolipoprotein concentrations in a group of swine expressing the FHC-D phenotype.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Animals
The FHC swine used in this study were derived from a strain developed and propagated for several generations at the University of Wisconsin (Immunogenetic Project Herd).^{13 14 19} These animals were fed a low cholesterol (65 mg/d), low fat (3% corn oil and 3% lard) diet (University of Wisconsin Diet). The age, weight, and serum TC of the 16 animals ranged from 19 to 27 weeks, 67 to 75 kg, and 250 to 422 mg/dL, respectively, when the study began.

Sixteen animals (8 males and 8 females) were divided into four groups of 2 males and 2 females each. The groups were arranged to have similar average plasma TC levels. Group 1 served as the control and was fed a placebo, while groups 2, 3, and 4 were fed 80, 200, or 400 mg of simvastatin, respectively, for 3 weeks. Simvastatin (Zocor, 40 mg per tablet) was obtained from Twin City Wholesale Drug Co. The tablets were crushed and mixed with a small amount of feed in the laboratory, which was then added to one fifth of the daily ration (2.6 kg/d, 3530 kcal/kg) and fed individually to ensure complete drug intake. Blood was collected twice a week during the 8-week period (2 weeks before, 3 weeks during, and 3 weeks after treatment) after an overnight fasting into Na₂EDTA for plasma and without anticoagulant for sera.¹⁹ The animals were treated according to the standards set in "Guide for the Care and Use of Laboratory Animals" (NIH publication No. 85-23).

Isolation of Plasma VLDL
VLDL (d<1.006 g/mL) was isolated from plasma of all 16 animals on days 0 and 21 of the drug treatment and day 21 after drug treatment, according to the method of Havel et al.²⁴ Plasma (3 mL) was overlaid with 2 mL NaCl solution of d=1.006 g/mL and centrifuged for 24 hours at 45 000 rpm at 10°C.

Lipid Measurements
Serum TC, HDL-C, TG, and plasma VLDL-C were determined by enzymatic procedures as described previously¹⁹ using Sigma diagnostic kits. In plasma samples from which VLDL was isolated by ultracentrifugation, the actual measured VLDL-C concentration was considerably lower (1.9 to 3.4 mg/dL) than the estimated value obtained by TG/5 (Friedewald formula), which is used for the estimation of human LDL-C. Therefore, LDL-C in all serum samples was calculated as TC-HDL-C. Lathosterol was determined by gas-liquid chromatography as described previously.²⁵ Since serum lathosterol is highly correlated with TC in other species, probably due to a physicochemical equilibration of liver lathosterol with serum lipoproteins,²⁵ the lathosterol/TC ratio was also calculated. This ratio in humans was shown to be an indicator of whole-body cholesterol synthesis and was clearly decreased by simvastatin.²⁵ Glucose was determined according to the method of Trinder,²⁶ using Sigma diagnostic kit No. 315.

Apolipoprotein Measurements
Apolipoproteins were measured by the single radial immunodiffusion test as described previously.^{13 20 27} Standardization of apoA-I, B, C-III, and E has been published.^{13 14 19 20}

LCAT Activity and Endogenous Plasma FER
LCAT Activity (Exogenous Assay)
The amount of LCAT present in plasma collected on days 0 and 21 of the on-drug period and day 21 of the postdrug period was estimated by an exogenous assay using the liposome substrate prepared according to Manabe et al.²⁸ The reaction was initiated by adding 10 µL plasma to 200 µL of the substrate. Incubations were carried out in duplicates at 37°C for 5 hours, and the reaction was stopped by adding 2 mL isopropanol. After the precipitates were removed the isopropanol extract was evaporated to dryness, and the free and esterified cholesterol fractions were separated by thin-layer chromatography. Radioactivity was measured by scintillation counting, and the FER was calculated as the difference between the percentage of radioactive cholesterol esterified before and after incubation. LCAT activity was calculated by multiplying the fractional rate (percent cholesterol esterified time) by the amount of free cholesterol present in the substrate. The LCAT activity measured by this method has been shown to be proportional to the LCAT mass.

Endogenous Assay
The FER of whole plasma or HDL-s was determined by measuring the rate of esterification of [³H]cholesterol as described by Dobiasova et al.²⁹ HDL-s was obtained after apoB-containing lipoproteins were precipitated in the plasma with phosphotungstate-MgCl₂.³⁰ The 200-µL aliquots of plasma or HDL-s were incubated overnight at 4°C with filter paper discs impregnated with [³H]cholesterol to allow the equilibration of the labeled cholesterol with the lipoprotein pool. After labeling, the plasma/HDL-s was incubated for 30 minutes at 37°C. Samples of 50 µL were removed before and after incubation, and the lipids were extracted with 1 mL isopropanol. The remainder of the procedure was the same as described for the exogenous assay above.

Calculations and Statistical Analysis
Data on serum concentrations of lipids and apolipoproteins were analyzed in the following manner: For each animal, the basal level was calculated as the average values of five predrug samplings (days 14, 11, 7, 4, and 0 predrug treatment) and three postdrug samplings (days 14, 17, and 21 postdrug administration). The postdrug time points were chosen after it was observed that serum and LDL-C levels had returned to a stable value 2 weeks after the simvastatin treatment (Fig 1B, C, D). Likewise, for each animal, the on-drug value was calculated as the average of the six serum samplings (days 3, 7, 10, 14, 17, and 21) taken during drug administration. The individual animal's response to the drug was then calculated as the difference () between the average on-drug and average basal value. These changes were then taken into the statistical analysis (one-way ANOVA, followed by Fisher's protected least significant difference test if P-ANOVA was <.05) to estimate if the responses in the four groups differed from each other. A one-sample t test was done to see if the mean delta significantly differed from zero.

View larger version (35K): [in this window] [in a new window]   Figure 1. Line graphs show the response of plasma LDL-C to simvastatin in four groups of FHC swine (n=4). A, group 1, placebo; B, group 2, simvastatin 80 mg/d; C, group 3, simvastatin 200 mg/d; and D, group 4, simvastatin 400 mg/d during 14 days pretreatment, 21 days of drug treatment, and 21 days posttreatment. F and M indicate females and males.

	Results

Top Abstract Introduction Methods Results Discussion References

 
At the initiation of the drug treatment, the 16 pigs had a body weight of 71±15 kg (mean±SD), and at the end of the 3-week period of drug administration, the body weight had increased by 14±1.2 kg with no differences between the four groups before and after drug treatment. The animals were of the FHC-D cholesterol phenotype, and their plasma cholesterol varied from 250 to 422 mg/dL at the initiation of the study.

In the animals receiving the placebo, all measured serum parameters were reasonably stable over the 8 weeks of the study, as illustrated for LDL-C in Fig 1A, except for 1 male that had a decrease of these parameters in the pretreatment period. The changes in LDL-C induced by simvastatin at 80, 200, and 400 mg/d are shown in Fig 1B, C, and D, respectively. TC and apoB (Table 1) showed patterns similar to that of LDL-C. The onset of the effect was rapid and reached its maximum drop after 7 or 10 days of drug administration. The responses of LDL-C to simvastatin varied between animals and were from +20 to -88 mg/dL, -71 to -137 mg/dL, and -66 to -80 mg/dL for the 80, 200, and 400 mg/d doses, respectively. After the drug administration was stopped it took 2 weeks before a stable basal value had been reached again. On the basis of this time pattern, the responses of the various serum parameters in each animal were calculated as the average on-drug level minus the average basal level in the 2 weeks before and the third week after drug treatment.

View this table: [in this window] [in a new window]   Table 1. Basal Levels and Effect of Simvastatin on Serum Concentrations of Cholesterol, TG, Lathosterol, and Apo A-I, B, C-III, and E in FHC Swine

The mean basal levels of serum lipids and apolipoproteins and the mean drug responses () of these parameters in the four groups receiving 0, 80, 200, or 400 mg/d simvastatin are given in Table 1. Simvastatin lowered TC by 14%, 25%, and 15%; LDL-C by 16%, 27%, and 17%; HDL-C by 3%, 12%, and 0%; TG by 3%, 10%, and 0%; lathosterol by 16%, 40%, and 27%; lathosterol/TC ratio by 4%, 21%, and 14%; apoA-I by 2%, 11%, and 2%; apoB by 8%, 22%, and 9%; apoC-III by 7%, 37%, and 18%; and apoE by 17%, 24%, and 19%, for the groups receiving 80, 200, and 400 mg/d, respectively. In contrast, VLDL-C tended to increase in all treatment groups. As expected from previous studies,^{25 31} lathosterol was highly correlated with TC (r=.58 for the basal levels, r=.82 for the levels during drug treatment).

Statistical analysis showed that the basal values did not differ significantly between the four groups, except for the lathosterol/TC ratio, and that the change in the placebo group did not differ significantly from zero for any of the serum parameters. In the group receiving simvastatin at 200 mg/d, the changes differed significantly from zero and from those of the placebo group for TC, LDL-C, HDL-C, lathosterol, apoA-I, apoB, apoC-III, and apoE. In contrast, simvastatin at 200 mg/d did not significantly affect serum TG, VLDL-C, or the lathosterol/TC ratio compared with the placebo group (Table 1).

Simvastatin was less active at doses of 80 and 400 mg/d than at 200 mg/d. For either or both of these doses, the changes were still significantly different from zero and from those in the placebo group for TC, LDL-C, lathosterol, and apoB, but not for HDL-C, apoA-I, apoC-III, and apoE (Table 1). In both absolute and relative terms, the simvastatin-induced decreases in LDL-C and apoB were greater than those in HDL-C and apoA-I, respectively. In relative terms, the decreases of lathosterol, apoC-III, and E were comparable with that of apoB. The changes for LDL-C, HDL-C, apoA-I, B, C-III, and E were all significantly correlated with each other (Table 2).

View this table: [in this window] [in a new window]   Table 2. Pearson Correlation Coefficients Between the Simvastatin Induced Changes ()1 in the Lipid and Apolipoprotein Levels

LCAT activity in serum and FER in plasma and the HDL supernatant were measured in samples obtained on day 0 and 21 of the on-drug period and day 21 of the postdrug period. No significant effects were observed in the parameters studied; however, two males in group 2 (80 mg/d) had considerably lower levels of LCAT activity and FER (Fig 2A, B, and C), which are reflected in the mean values for that group. No significant changes in plasma glucose concentrations were observed from predrug (day 0) to 3 weeks of drug treatment (day 21) for placebo (67±15.4 versus 80±9.9 mg/dL); simvastatin at 80 mg/d (59±12.5 versus 68±18.8 mg/dL); 200 mg/d (69±8.1 versus 73±9.6 mg/dL); and 400 mg/d (65±7.9 versus 76±15 mg/dL), respectively.

View larger version (18K): [in this window] [in a new window]   Figure 2. Line graphs show the mean responses to simvastatin in four groups of FHC swine (n=4). A, LCAT activity in plasma; B, FER in plasma; and C, HDL-s. Group 1, placebo; group 2, simvastatin 80 mg/d; group 3, simvastatin 200 mg/d, and group 4, simvastatin 400 mg/d. Day 0 indicates predrug treatment; day 21, after 21 days of drug treatment; and day 42, 21 days posttreatment.

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
The purpose of the present study was to determine whether the FHC swine respond to HMG-CoA reductase inhibitors similarly to the human response. At the time that this study was undertaken, simvastatin appeared to be the most efficacious LDL-C–lowering drug registered and therefore was selected for this study.

The study shows that simvastatin modulates the lipid and apo profiles in the FHC swine in a similar but not equal manner to that observed with statins in humans.^{1 2 3 4 5 32 33 34 35 36 37 38} In FHC swine, LDL-C, apoB, apoC-III, and apoE show mean decreases of 27%, 22%, 37%, and 24%, respectively, the maximal effect being obtained at a dose of 200 mg/d (Table 1). However, unlike the moderate increase in HDL-C and apoA-I obtained with statins in humans,^{1 2 3 4 5 32 33 34 35 36 37 38} these parameters showed a moderate but significant decrease in the FHC swine at a dose of 200 mg/d. The FHC swine have low levels of VLDL-C and TG and, in contrast to humans, these parameters were not affected by simvastatin.

An important feature of the dose-response curve of the statins in humans is the flattening or plateau in the drop of LDL-C with increasing drug doses. As shown by Mol et al,² the effect of simvastatin on LDL-C and apoB starts to level off above 10 mg/d and essentially reaches a plateau at a dose of 40 mg/d. A number of studies in humans with primary moderate hypercholesterolemia, familial hypercholesterolemia, or familial combined hyperlipidemia have confirmed that the maximum drop of LDL-C achievable with lovastatin or simvastatin is between 35% and 40% below the predrug level, while the maximal drop of apoB is about 20% to 25%.^{1 2 3 5 32 33 34 35 36 37 38}

In the FHC swine, simvastatin was unable to induce a decrease >27% in LDL-C or 22% in apoB. Thus, FHC swine mimic humans in having a clear efficacy limitation toward simvastatin, with the efficacy of the drug even somewhat smaller than observed in humans with hypercholesterolemia. Other studies addressing the effect of statins in animals used only one dose of lovastatin or simvastatin,^{7 8 9 10 11 12} with the exception of the study in hamsters.⁷ The latter study showed no evidence of flattening in the dose-response curve, with LDL-C levels approaching zero upon increase of the lovastatin dose.

So far no satisfactory explanation has been provided for the efficacy limitation of the statins in humans. However, it is well known that treatment with lovastatin leads to an induction of the amount of HMG-CoA reductase and HMG-CoA synthase in the liver,^{39 40} and it may be reasoned that this counter-regulation prevents a further decrease in mevalonate synthesis (and so a further drop in LDL-C) despite increase in the drug dose. Our previous observation that a tocotrienol-rich fraction is able to lower LDL-C in the FHC swine by 60%⁴¹ gives support to this hypothesis. Parker et al⁴² showed that tocotrienol lowers reductase activity by decreasing the amount of enzyme protein, and it can be envisaged that this leads to a stronger decrease of mevalonate synthesis than achievable by competitive inhibition with a statin. To further address this possibility, we determined the lathosterol/TC ratio in the FHC swine, a parameter validated to reflect the whole-body cholesterol synthesis in humans²⁵ and rabbits³¹ and shown to decrease during simvastatin treatment.²⁵ No significant drop was observed with any of the doses, which is in contrast to the findings in humans and rabbits but in line with the hypothesis that the direct inhibitory effect of simvastatin on reductase is strongly counteracted by the upregulation of HMG-CoA synthase and reductase.

A second feature that is often not addressed when results of statins in humans are compared with those obtained in animals is the apparent difference in drug potency. In humans, ED₅₀ of simvastatin is approximately 5 mg/d, ie, 0.1 to 0.2 mg/kg per day.² In the FHC swine, ED₅₀ is about 80 mg/d, ie, 1 mg/kg per day, or 5- to 10-fold higher than in humans. Reasons for a higher potency in humans may be differences in age, the diet, and/or genetics. The FHC swine were young (5 to 7 months) compared with humans (35 to 70 years). In contrast to the human diet containing about 12% fat by weight and 300 to 700 mg/d cholesterol, the FHC swine consumed a diet lower in fat (3% corn oil and 3% lard) and cholesterol (65 mg/d). A different genetic makeup of the FHC swine may account for a higher metabolism or less-effective absorption of the drug, leading to a lower potency.

Simvastatin had no significant effect on LCAT activity at any of the doses administered. This finding is in agreement with reports of Zhao et al⁴³ in familial dysbetalipoproteinemic patients and Warden et al,⁴⁴ who showed that HMG-CoA reductase inhibitors had no effect on LCAT mRNA levels in mice. Simvastatin also failed to produce a significant impact on the rate of plasma and HDL-C esterification.²⁹ While the rate of plasma cholesterol esterification is dependent on the levels of LCAT,⁴⁵ the available cholesteryl ester transfer protein activity and the composition of HDL (the primary substrate for LCAT) are also considered rate limiting.⁴⁶ Because LCAT levels appeared unaltered after treatment, and the pig has only marginal cholesteryl ester transfer protein activity,⁴⁷ the findings of this study are consistent in that simvastatin is not likely to produce marked alterations in the composition of HDL.

In summary, this study shows that lipids and apolipoproteins in FHC swine respond to simvastatin in the same direction as in humans, although the dose-response curve is different (lower potency and smaller maximal response). Furthermore, simvastatin appeared to have little effect on whole-body cholesterol synthesis as determined by the lathosterol/TC ratio. In spite of these differences, the FHC animals appear to be the best nonprimate animal model to assess the power of lipid-lowering compounds for the prevention or treatment of atherosclerosis.

	Selected Abbreviations and Acronyms

 

apo = apolipoprotein FER = fractional rates of cholesterol esterification FHC = familial hypercholesterolemia in swine HDL-C = HDL cholesterol HDL-s = HDL-supernatant HMG-CoA = 3-hydroxy-3-methylglutaryl coenzyme A LCAT = lecithin:cholesterol acyltransferase LDL-C = LDL cholesterol TC = total cholesterol TG = triglycerides VLDL-C = VLDL cholesterol

	Acknowledgments

 
This work was supported in part by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, and by a grant from Hoffmann La-Roche Ltd, Basel, Switzerland. We thank Scott Kirk, Rien Buytenhek, Gordon Gunderson, and Roland Stoltenberg for their excellent technical support. This is paper No. 3434 from the Department of Genetics. We appreciate the reviewer's comments and suggestions.

Received May 9, 1995; accepted October 11, 1995.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Bradford RH, Shear CL, Chremos AN, Dujovne C, Downton M, Franklin FA, Gould LA, Hesney M, Higgins J, Hurley DP, Langendorfer A, Nash DT, Pool JL, Schnaper H. Expanded Clinical Evaluation of Lovastatin (EXCEL) study results, I: efficacy in modifying plasma lipoproteins and adverse event profile in 8245 patients with moderate hypercholesterolemia. Arch Intern Med.. 1991;151:43-49. [Abstract/Free Full Text]

2. Mol MJTM, Erkelens DW, Gevers Leuven JA, Schouten JA, Stalenhoef AFH. Effects of synvinolin (MK-733) on plasma lipids in familial hypercholesterolemia. Lancet.. 1986;2:936-939. [Medline] [Order article via Infotrieve]

3. Havel RJ, Hunninghake DB, Illingworth DR, Lees RS, Stein EA, Tobert JA, Bacon SR, Bolognese JA, Frost PH, Lamkin GE, Lees AM, Leon AS, Gardner K, Johnson G, Mellies MJ, Rhymer PA, Tun P. Lovastatin (mevinolin) in the treatment of heterozygous familial hypercholersterolemia: a multicenter study. Ann Intern Med.. 1987;107:609-615.

4. Vega GL, East C, Grundy SM. Lovastatin therapy in familial dysbetalipoproteinemia: effects on kinetics of apolipoprotein B. Atherosclerosis.. 1988;70:131-143. [Medline] [Order article via Infotrieve]

5. Arad Y, Ramakrishnan R, Ginsberg HN. Lovastatin therapy reduces low density lipoprotein apoB levels in subjects with combined hyperlipidemia by reducing the production of apoB-containing lipoproteins: implications for the pathophysiology of apoB production. J Lipid Res.. 1990;31:567-582. [Abstract]

6. Garg A, Grundy SM. Lovastatin for lowering cholesterol levels in non-insulin-dependent diabetes mellitus. N Engl J Med.. 1988;318:81-86. [Abstract]

7. Ma PTS, Gil G, Südhof TC, Bilheimer DW, Goldstein JL, Brown MS. Mevinolin, an inhibitor of cholesterol synthesis, induces mRNA for low density lipoprotein receptor in livers of hamsters and rabbits. Proc Natl Acad Sci U S A.. 1986;83:8370-8374. [Abstract/Free Full Text]

8. Himber J, Missano B, Rudling U, Hennes M, Kempen HJ. Effect of stigmastanylphosphorylcholine (Ro 16-6532) and lovastatin on lipid and ipoprotein levels and lipoprotein metabolisms in the hamster on different diets. J Lipid Res.. 1995;36:1567-1585. [Abstract]

9. Amin D, Gustafson S, Perrone MH. Lovastatin is hypertriglyceridemic in Syrian golden hamsters. Biochem Biophys Res Commun.. 1988;157:530-534. [Medline] [Order article via Infotrieve]

10. Endo A. The discovery and development of HMG-CoA reductase inhibitors. J Lipid Res.. 1992;33:1569-1582. [Medline] [Order article via Infotrieve]

11. Kovanen PT, Bilheimer DW, Goldstein JL, Jaramillo JJ, Brown MS. Regulatory role for hepatic low density lipoprotein receptors in vivo in the dog. Proc Natl Acad Sci U S A.. 1981;78:1194-1198. [Abstract/Free Full Text]

12. Huff MW, Telford DE. Regulation of low density lipoprotein apoprotein B metabolism by lovastatin and cholestyramine in miniature pigs: effects on LDL composition and synthesis of LDL subfractions. Metabolism.. 1989;38:256-264. [Medline] [Order article via Infotrieve]

13. Rapacz J, Hasler-Rapacz J. Investigations on the relationship between immunogenetic polymorphism of ß-lipoproteins and the ß-lipoprotein and cholesterol levels in swine. In: Lenzi S, Descovich GD, eds. Atherosclerosis and Cardiovascular Diseases. Bologna, Italy: Editrice Compositori; 1984:99-108.

14. Hasler-Rapacz J, Prescott MF, Von Linden-Reed J, Rapacz JM Jr, Hu Z, Rapacz J. Elevated concentrations of plasma lipids and apolipoproteins B, C-III, and E are associated with the progression of coronary artery disease in familial hypercholesterolemic swine. Arterioscler Thromb Vasc Biol.. 1995;15:583-592. [Abstract/Free Full Text]

15. Rapacz J, Dentine MR, Hasler-Rapacz J, Rapacz JM Jr. A major familial hypercholesterolemia subphenotype in swine is inherited as an autosomal recessive trait and its gene is not linked to the apoB locus. Atherosclerosis.. 1994;109:6. Abstract.

16. Brown MS, Goldstein JL. Familial hypercholesterolemia, a genetic defect of the low-density lipoprotein receptor. N Engl J Med.. 1976;294:1386-1390. [Medline] [Order article via Infotrieve]

17. Prescott MF, McBride CH, Hasler-Rapacz J, Von Linden J, Rapacz J. Development of complex atherosclerotic lesions in pigs with inherited hyper-LDL cholesterolemia (IHLC) bearing mutant alleles for apolipoprotein B. Am J Pathol.. 1991;139:139-147. [Abstract]

18. Prescott MF, Hasler-Rapacz J, Von Linden-Reed J, Rapacz J. Familial hypercholesterolemia associated with coronary atherosclerosis in swine bearing different alleles for apolipoprotein B. In: Numano F, Wissler RW, eds. Atherosclerosis III: Recent Advances in Atherosclerosis Research. New York, NY: Annals of the New York Academy of Science; 1995;748:283-293.

19. Hasler-Rapacz JO, Nichols TC, Griggs TR, Bellinger DA, Rapacz J. Familial and diet-induced hypercholesterolemia in swine: lipid, ApoB, and ApoA-I concentrations and distributions in plasma and lipoprotein subfractions. Arterioscler Thromb.. 1994;14:923-930. [Abstract/Free Full Text]

20. Lee DM, Mok T, Hasler-Rapacz J, Rapacz J. Concentrations and compositions of plasma lipoprotein subfractions of Lpb⁵-Lpu¹ homozygous and heterozygous swine with hypercholesterolemia. J Lipid Res.. 1990;13:839-847.

21. Lowe SW, Checovich WJ, Rapacz J, Attie AD. Defective receptor binding of low density lipoproteins from pigs possessing mutant apolipoprotein B alleles. J Biol Chem.. 1988;263:15467-15473. [Abstract/Free Full Text]

22. Checovich WJ, Fitch WL, Krauss RM, Smith MP, Rapacz J, Smith CL, Attie AD. Defective catabolism and abnormal composition of low-density lipoproteins from mutant pigs with hypercholesterolemia. Biochemistry.. 1988;27:1934-1941. [Medline] [Order article via Infotrieve]

23. Aiello RJ, Nevin DN, Ebert DL, Uelmen PJ, Kaiser ME, MacCluer JW, Blangero J, Dyer TD, Attie AD. Apolipoprotein B and a second major gene locus contribute to phenotypic variation of spontaneous hypercholesterolemia in pigs. Arterioscler Thromb.. 1994;14:409-419. [Abstract/Free Full Text]

24. Havel RJ, Eder HA, Bragdon JH. The distribution and chemical composition of ultracentrifugally separated lipoproteins in human serum. J Clin Invest.. 1955;34:1345-1353.

25. Kempen HJM, Glatz JFC, Gevers Leuven JA, van der Voort HA, Katan MB. Serum lathosterol concentration is an indicator of whole-body cholesterol synthesis in humans. J Lipid Res.. 1988;29:1149-1155. [Abstract]

26. Trinder P. Determination of glucose in blood using glucose oxidase with an alternative oxygen acceptor. Ann Clin Biochem.. 1969;6:24-27.

27. Mancini G, Carbonara AO, Heremans JF. Immunochemical quantitation of antigens by single radial immunodiffusion. Immunochem.. 1965;2:235-254. [Medline] [Order article via Infotrieve]

28. Manabe M, Abe T, Nozawa M, Maki A, Hirata M, Itakura H. New substrate for determination of serum lecithin cholesterol:acyltransferase. J Lipid Res.. 1987;28:1206-1215. [Abstract]

29. Dobiasova M, Stribrna J, Sparks DL, Pritchard PH, Frohlich JJ. Cholesterol esterification rates in very low density lipoprotein– and low density lipoprotein–depleted plasma: relation to high density lipoprotein subspecies, sex, hyperlipidemia, and coronary artery disease. Arterioscler Thromb.. 1991;11:64-70. [Abstract/Free Full Text]

30. Burstein M, Scholnick HR, Morfin R. Rapid method for the isolation of lipoproteins from human serum by precipitation with polyanions. J Lipid Res.. 1970;11:583-595. [Abstract]

31. Meijer GW, Van der Palen JGP, De Vries H, Kempen HJM, Van der Voort HA, Van Zutphen LFM, Beynen AC. Evaluation of the use of serum lathosterol concentration to assess whole-body cholesterol synthesis in rabbits. J Lipid Res.. 1992;33:281-286. [Abstract]

32. Grundy SM, Vega GL. Influence of mevinolin on metabolism of low density lipoproteins in primary moderate hypercholesterolemia. J Lipid Res.. 1985;26:1464-1475. [Abstract]

33. Mol MJTM, Erkelens DW, Gevers Leuven JA, Schouten JA, Stalenhoef AFH. Simvastatin (MK-733): a potent cholesterol synthesis inhibitor in heterozygous familial hypercholesterolaemia. Atherosclerosis.. 1988;69:131-137. [Medline] [Order article via Infotrieve]

34. The Simvastatin Pravastatin Study Group. Comparison of the efficacy, safety and tolerability of simvastatin and pravastatin for hypercholesterolemia. Am J Cardiol.. 1993;71:1408-1414. [Medline] [Order article via Infotrieve]

35. Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering of 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet.. 1994;344:1383-1389. [Medline] [Order article via Infotrieve]

36. Alaupovic P, Hodis HN, Knight-Gibson C, Mack WJ, LaBree L, Cashin-Hemphill L, Corder CN, Kramsch DM, Blakenhorn DH. Effects of lovastatin on apoA- and apoB-containing lipoproteins: families in a subpopulation of patients participating in the Monitored Atherosclerosis Regression Study (MARS). Arterioscler Thromb.. 1994;14:1906-1914. [Abstract/Free Full Text]

37. Farnier M, Bonnefous F, Debbas N, Irvine A. Comparative efficacy and safety of micronized fenofibrate and simvastatin in patients with primary type IIa or IIb hyperlipidemia. Arch Intern Med.. 1994;154:441-449. [Abstract/Free Full Text]

38. Keech A, Collins R, MacMahon S, Armitage J, Lawson A, Wallendszus K, Fatemian M, Kearney E, Lyon V, Mindell J, Mount J, Painter R, Parish S, Slavin B, Sleight P, Youngman L, Peto R. Three-year follow-up of the Oxford Cholesterol Study: assessment of the efficacy and safety of simvastatin in preparation for a large mortality study. Eur Heart J.. 1994;15:255-269. [Abstract/Free Full Text]

39. Singer II, Kawka DW, Kazazis DM, Alberts AW, Chen JS, Huff JW, Ness GC. Hydroxymethylglutaryl-coenzyme A reductase-containing hepatocytes are distributed periportally in normal and mevinolin-treated rat livers. Proc Natl Acad Sci U S A.. 1984;81:5556-5560. [Abstract/Free Full Text]

40. Li AC, Tanaka RD, Callaway K, Fogelman AM, Edwards PA. Localization of 3-hydroxy-3-methylglutaryl CoA reductase and 3-hydroxy-3-methylglutaryl CoA synthase in the rat liver and intestine is affected by cholestyramine and mevinolin. J Lipid Res.. 1988;29:781-796. [Abstract]

41. Qureshi AA, Qureshi N, Hasler-Rapacz JO, Weber FE, Chaudhary V, Crenshaw TD, Gapor A, Ong ASH, Chong YH, Peterson D, Rapacz J. Dietary tocotrienols reduce concentrations of plasma cholesterol, apolipoprotein B, thromboxane-B₂ and platelet factor 4 in pigs with inherited hyperlipidemias. Am J Clin Nutr.. 1991;53:1042S-1046S. [Abstract/Free Full Text]

42. Parker RA, Pearce BC, Clark RW, Gordon DA, Wright JJK. Tocotrienols regulate cholesterol production in mammalian cells by post-transcriptional suppression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. J Biol Chem.. 1993;268:11230-11238. [Abstract/Free Full Text]

43. Zhao S-P, Smelt AHM, Van den Maagdenberg AMJM, Van Tol A, Vroom TFFP, Gevers Leuven JA, Frants RR, Havekes LM, Van der Laarse A, Van 't Hooft FM. Plasma lipoproteins in familial dysbetalipoproteinemia associated with apolipoproteins E2(Arg158Cys), E3-Leiden, and E2(Lys146Gln), and effects of treatment with simvastatin. Arterioscler Thromb.. 1994;14:1705-1716. [Abstract/Free Full Text]

44. Warden CH, Langner CA, Gordon JI, Taylor BA, McLean JW, Lusis AJ. Tissue specific expression, developmental regulation and chromosomal mapping of the lecithin: cholesterol acyltransferase gene. J Biol Chem.. 1989;264:21573-21581. [Abstract/Free Full Text]

45. Albers JJ, Chen CH, Adolphson JL. Lecithin:cholesterol acyltransferase (LCAT) mass: its relationship to LCAT activity and cholesterol esterification rate. J Lipid Res.. 1981;22:1206-1213. [Abstract]

46. Francone OL, Gurakar A, Fielding C. Distribution and functions of lecithin:cholesterol acyltransferase and cholesteryl ester transfer protein in plasma lipoproteins. J Biol Chem.. 1989;264:7066-7072. [Abstract/Free Full Text]

47. Ha YC, Calvert GD, McIntosh GH, Barter PJ. A physiologic role of the esterified cholesterol transfer protein: in vivo studies in rabbits and pigs. Metabolism.. 1981;30:380-383.[Medline] [Order article via Infotrieve]

This article has been cited by other articles:

				F. S. Czepluch and J. Waltenberger High-dose atorvastatin is associated with impaired myocardial angiogenesis in response to vascular endothelial growth factor in hypercholesterolemic swine: Relevance to the human situation? J. Thorac. Cardiovasc. Surg., June 1, 2007; 133(6): 1685 - 1686. [Full Text] [PDF]

				A. R. Chade, X. Zhu, O. P. Mushin, C. Napoli, A. Lerman, and L. O. Lerman Simvastatin promotes angiogenesis and prevents microvascular remodeling in chronic renal ischemia FASEB J, August 1, 2006; 20(10): 1706 - 1708. [Abstract] [Full Text] [PDF]

				S. H. Wilson, A. R. Chade, A. Feldstein, T. Sawamura, C. Napoli, A. Lerman, and L. O. Lerman Lipid-lowering-independent effects of simvastatin on the kidney in experimental hypercholesterolaemia Nephrol. Dial. Transplant., April 1, 2003; 18(4): 703 - 709. [Abstract] [Full Text] [PDF]

				P. O. Bonetti, S. H. Wilson, M. Rodriguez-Porcel, D. R. Holmes Jr, L. O. Lerman, and A. Lerman Simvastatin preserves myocardial perfusion and coronary microvascular permeability in experimental hypercholesterolemia independent of lipid lowering J. Am. Coll. Cardiol., August 7, 2002; 40(3): 546 - 554. [Abstract] [Full Text] [PDF]

				S. H. Wilson, R. D. Simari, P. J. M. Best, T. E. Peterson, L. O. Lerman, M. Aviram, K. A. Nath, D. R. Holmes Jr, and A. Lerman Simvastatin Preserves Coronary Endothelial Function in Hypercholesterolemia in the Absence of Lipid Lowering Arterioscler Thromb Vasc Biol, January 1, 2001; 21(1): 122 - 128. [Abstract] [Full Text] [PDF]

				J. R. Burnett, L. J. Wilcox, D. E. Telford, S. J. Kleinstiver, P. H. R. Barrett, R. S. Newton, and M. W. Huff Inhibition of HMG-CoA Reductase by Atorvastatin Decreases Both VLDL and LDL Apolipoprotein B Production in Miniature Pigs Arterioscler Thromb Vasc Biol, November 1, 1997; 17(11): 2589 - 2600. [Abstract] [Full Text]

This Article Abstract Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hasler-Rapacz, J. Articles by Rapacz, J. Search for Related Content PubMed PubMed Citation Articles by Hasler-Rapacz, J. Articles by Rapacz, J. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CHOLESTEROL