Normolipemic and genetically hypercholesterolemic pigs of defined lipoprotein genotype were fed a standard diet supplemented with 50 micrograms/g tocotrienol-rich fraction (TRF) isolated from palm oil. Hypercholesterolemic pigs fed the TRF supplement showed a 44% decrease in total serum cholesterol, a 60% decrease in low-density-lipoprotein (LDL)-cholesterol, and significant decreases in levels of apolipoprotein B (26%), thromboxane-B2 (41%), and platelet factor 4 (PF4; 29%). The declines in thromboxane B2 and PF4 suggest that TRF has a marked protective effect on the endothelium and platelet aggregation. The effect of the lipid-lowering diet persisted only in the hypercholesterolemic swine after 8 wk feeding of the control diet. These results support observations from previous studies on lowering plasma cholesterol in animals by tocotrienols, which are naturally occurring compounds in grain and palm oils and may have some effect on lowering plasma cholesterol in humans.

A strain of pigs bearing three immunogenetically defined lipoprotein-associated markers (allotypes), designated Lpb5, Lpr1, and Lpu1, has marked hypercholesterolemia on a low fat, cholesterol-free diet. Unlike individuals with familial hypercholesterolemia or WHHL rabbits, the affected pigs have normal low density lipoprotein receptor activity. The animals, by 7 months of age, have extensive atherosclerotic lesions in all three coronary arteries. This strain of pig represents an animal model for atherosclerosis and hypercholesterolemia associated with mutations affecting the structures of plasma lipoproteins. One of the variant apolipoproteins, Lpb5, is apolipoprotein-B. A second variant apolipoprotein (Lpr1), termed apo-R, is a 23-kilodalton protein present in both the very low density (d less than 1.006 g/ml) and the very high density (d greater than 1.21 g/ml) fractions of pig plasma. Isoforms of this protein correlate with two Lpr alleles, Lpr1 and Lpr2. The Lpr genes segregate independently of the Lpb5 and Lpu1 alleles. The Lpu1 allotype is a component of low density lipoprotein and is genetically linked to Lpb5.

Elevated blood plasma cholesterol (hypercholesterolemia) is a major risk factor for coronary artery disease (CAD) in humans. Genetic dissection of polygenic lipid and lipoprotein disorders in swine, a key animal model for the study of familial hypercholesterolemia (FH) and CAD, led to the isolation of a monogenic subphenotype (FH-r), that is inherited in the recessive (r) manner. A genome scan mapped the FH-r locus close to the centromere of chromosome 2. Comparative mapping showed that this region shares homology with a part of human chromosome 19 that harbors the low density lipoprotein receptor (LDLR) locus, and therefore suggested LDLR as the prime candidate gene for FH-r. Cloning and sequencing of hepatic LDLR cDNA from two FH-r/r and one normal (N/N) animals disclosed a single missense mutation (R84C) in a region that corresponds to human exon 4. The C84 mutation cosegregates invariantly with hypercholesterolemia, which strongly suggests that this mutation is responsible for the observed hyperlipidemia.

A tocotrienol-rich fraction (TRF(25)) and novel tocotrienols (d-P(21)-T3 and d-P(25)-T3) of rice bran significantly lowered serum and low density lipoprotein cholesterol levels in chickens. The present study evaluated the effects of novel tocotrienols on lipid metabolism in swine expressing hereditary hypercholesterolemia. Fifteen 4-mo-old genetically hypercholesterolemic swine were divided into five groups (n = 3). Four groups were fed a corn-soybean control diet, supplemented with 50 microg of either TRF(25), gamma-tocotrienol, d-P(21)-T3 or d-P(25)-T3 per g for 6 wk. Group 5 was fed the control diet for 6 wk and served as a control. After 6 wk, serum total cholesterol was reduced 32-38%, low density lipoprotein cholesterol was reduced 35-43%, apolipoprotein B was reduced 20-28%, platelet factor 4 was reduced 12-24%, thromboxane B(2) was reduced 11-18%, glucose was reduced 22-25% (P<0.01), triglycerides were reduced 15-19% and glucagon was reduced 11-17% (P<0.05) in the treatment groups relative to the control. Insulin was 100% greater (P<0.01) in the treatment groups than in the control group. Preliminary data (n = 1) indicated that hepatic activity of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase was lower in the treatment groups, and cholesterol 7alpha-hydroxylase activity was unaffected. Cholesterol and fatty acid levels in various tissues were lower in the treatment groups than in control. After being fed the tocotrienol-supplemented diets, two swine in each group were transferred to the control diet for 10 wk. The lower concentrations of serum lipids in these four treatment groups persisted for 10 wk. This persistent effect may have resulted from the high tocotrienol levels in blood of the treatment groups, suggesting that the conversion of tocotrienols to tocopherols may not be as rapid as was reported in chickens and humans.

Elevated blood plasma cholesterol (hypercholesterolemia) is a major risk factor for coronary artery disease (CAD) in humans. Genetic dissection of polygenic lipid and lipoprotein disorders in swine, a key animal model for the study of familial hypercholesterolemia (FH) and CAD, led to the isolation of a monogenic subphenotype (FH-r), that is inherited in the recessive (r) manner. A genome scan mapped the FH-r locus close to the centromere of chromosome 2. Comparative mapping showed that this region shares homology with a part of human chromosome 19 that harbors the low density lipoprotein receptor (LDLR) locus, and therefore suggested LDLR as the prime candidate gene for FH-r. Cloning and sequencing of hepatic LDLR cDNA from two FH-r/r and one normal (N/N) animals disclosed a single missense mutation (R84C) in a region that corresponds to human exon 4. The C84 mutation cosegregates invariantly with hypercholesterolemia, which strongly suggests that this mutation is responsible for the observed hyperlipidemia.

We reported earlier that a complex familial hypercholesterolemia (c-FHC) phenotype characterized by elevated levels of total plasma cholesterol (TC) and apoB and reduced levels of HDL cholesterol (HDL-C) and apoA-I is associated with the development of spontaneous atherosclerotic lesions in swine. In this study, we investigated concentrations of plasma lipids and apolipoproteins B, C-III, and E in six parental animals of two cholesterol concentration phenotypes and their 32 offspring, which segregated into high, intermediate, and normal cholesterol phenotypes. Subsequently, we compared the extent of atherosclerotic lesion development in coronary arteries to the concentrations of plasma lipids and apolipoproteins in the parents and two offspring per family. Mean concentrations for the high (n = 23), intermediate (n = 13), and normal (n = 2) cholesterol level phenotypes at 4 months of age were TC, 316 +/- 62.2, 159 +/- 17.1, and 105 +/- 12 mg/dL; LDL cholesterol, 275 +/- 63.1, 113 +/- 16.4, and 67 +/- 18.4 mg/dL; HDL-C, 35 +/- 6.1, 41 +/- 5.7, and 33 +/- 6.4 mg/dL; triglycerides, 48 +/- 10.8, 39 +/- 8.0, and 29 +/- 5.7 mg/dL; apoB, 152 +/- 32.5, 80 +/- 7.2, and 48 +/- 5.7 mg/dL; apoC-III, 10 +/- 4.2, 8 +/- 1.7, and 3 +/- 0.1 mg/dL; and apoE, 17 +/- 3.4, 7 +/- 1.7, and 5 +/- 0.7 mg/dL, respectively. Histological analysis of the major coronary arteries from members of the three families showed considerable variation in the severity of lesions, ranging from foci of adaptive intimal thickening consisting of two to six layers of smooth muscle cells to advanced lesions containing necrotic cores, cholesterol clefts, calcification, and hemorrhage (type V). The most extensive lesions occurred only in animals of the high cholesterol phenotype (ie, c-FHC), in which the concentration of TC and apoB progressively increased after 4 months of age, apoC-III, apoE, and triglycerides increased or remained elevated, and HDL-C decreased, except for one animal. Data presented here show that the plasma cholesterol phenotypes in FHC animals are associated with levels of apolipoproteins B, C-III, and E and indicate that the increases in the studied parameters after 4 months of age correlate with the progression of coronary artery disease.

Low levels of high-density lipoproteins (HDLs) may constitute an independent risk factor that may be as important as elevated low-density lipoproteins (LDLs) in coronary artery disease (CAD). Concentrations and distributions of lipids, apolipoprotein (apo) B, and apoA-I in the plasma and lipoprotein subfractions of two groups of swine, one with familial hypercholesterolemia (FHC) and the other with diet-induced hypercholesterolemia (DHC), were examined. Normolipidemic (NL) animals served as controls. All pigs carried the Lpb5 apoB mutation, which is known to influence the formation of atherosclerotic lesions. Mean concentrations of serum total cholesterol in NL, DHC, and FHC were 80.0+9.3, 774.3±54.5, and 316.5±36.1 mg/dL, respectively; HDL cholesterol (HDL-C), 33.5±1.9, 137.0±9.9, and 22.3±2.2 mg/dL; triglycerides, 33.0+16.3, 40.3±11.7, and 56.8±7.2 mg/dL; apoB, 35.7±3.1, 142.0±4.8, and 169.3+13.9 mg/dL; and apoA-I, 62.4±9.3, 170.9±6.9, and 42.6±4.8 mg/ dL. The distributions of total cholesterol, apoB, and apoA-I in plasma lipoprotein subfractions were also examined. Compared with NL, FHC had fourfold and 4.7-fold increases in total cholesterol and apoB, respectively, distributed in the lower densities (d< 1.043 g/mL), and low HDL-C and apoA-I levels, resulting in a high total cholesterol/HDL-C ratio (14.4:1) and elevated triglyceride levels. DHC was characterized by 10-fold and fourfold increases in total cholesterol and apoB, respectively, resulting in an LDL particle highly enriched in cholesterol, a fourfold increase of HDL-C, an almost threefold increase in apoA-I, and a normal triglyceride level. Thus FHC but not DHC exhibited a marked resemblance to familial combined hyperlipidemia, the most common endogenous dyslipidemia in humans. (Arterioscler Thromb. 1994;14: 923-930.) Key Words • swine • familial hypercholesterolemia • diet-induced hypercholesterolemia • plasma cholesterol • HDL cholesterol • apoB • apoA-I • triglycerides • immunochemistry at NORTH DAKOTA STATE UNIV on June 17, 2015 http://atvb.ahajournals.org/ Downloaded from at NORTH DAKOTA STATE UNIV on June 17, 2015 http://atvb.ahajournals.org/ Downloaded from J O Hasler-Rapacz, T C Nichols, T R Griggs, D A Bellinger and J Rapacz concentrations and distributions in plasma and lipoprotein subfractions. Familial and diet-induced hypercholesterolemia in swine. Lipid, ApoB, and ApoA-I

Brush borders, enterocytes, or both preparations obtained from the small intestine of 345 pedigreed pigs, carrying components of seven breeds, were tested by adhesion assay in vitro with 6 3 2 enteropathogenic Escherichia coli strains, each expressing one of the three K88 pilus antigens, K88ab, K88ac and K88ad. With few exceptions, all pigs were classified as belonging to one of four adhesion phenotypes: