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We estimated the effects of breast- and formula-feeding on cholesterol and bile acid metabolism for 1.5 years after weaning in 35 newborn baboons that were breast-fed (n = 12) or fed one of two formulas with high (n = 11) or low (n = 12) polyunsaturated/saturated (P/S) fatty acid composition. Infants were weaned at 15 weeks to a high cholesterol, saturated fat diet. Because formula P/S ratio did not affect any variable for 1.5 years after weaning, the data were averaged for the two formula groups. After weaning, serum cholesterol and lipoprotein cholesterol concentrations among the infant diet groups were not different until after 52 weeks of age. From 70 to 97 weeks of age, serum cholesterol and high density lipoprotein-2 (HDL2)-cholesterol (HDL2-C) concentrations were lower (P < 0.04) among baboons that were breast-fed as infants compared with those fed formulas. We observed no significant postweaning differences in low density lipoprotein (LDL)-C, HDL3-C, or serum apolipoprotein A-I, B, or E concentrations. At 97 weeks of age baboons that were breast-fed until 15 weeks compared with those formula-fed had a 25% lower total bile acid synthetic rate (36.6 vs. 48.6 mumol/day per kg body weight, P < 0.02) due principally to a 29% lower cholic acid synthetic rate (23.2 vs 32.5 mumol/day per kg body weight, P < 0.004). Baboons breast-fed as infants had a 44% higher hepatic LDL-receptor mRNA concentration than those formula-fed (1.45 vs. 1.01 pg mRNA/micrograms total RNA, P < 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

This study was designed to determine the differences in cholesterol metabolism due to dietary cholesterol and type of fat in adult baboons. From weaning at 16 wk to 7-8 y of age, 80 baboons were fed one of four diets: high cholesterol (0.24 mg/kJ) or low cholesterol (0.0024 mg/kJ) with 40% of energy from saturated fat [polyunsaturated/saturated fatty acid ratio (P/S) = 0.37] or unsaturated fat (P/S = 2.1). High cholesterol and saturated fat independently raised serum lipoprotein and apolipoprotein concentrations to about the same extent. The liver cholesterol concentration of baboons fed high cholesterol diets was 23% higher than that of baboons fed low cholesterol. High dietary cholesterol also increased bile cholesterol concentration by 25%, the neutral steroid excretion rate by 66% and the bile acid excretion rate by 30%. With feeding of saturated fat, compared with unsaturated fat, liver cholesterol was 24% lower, bile cholesterol 26% lower and the neutral steroid excretion rate 12% lower. Dietary cholesterol greatly suppressed whole-body cholesterol synthesis, but type of fat did not affect cholesterol synthesis rate. These results suggest that dietary cholesterol and saturated fat increase plasma lipoprotein concentrations through different physiological mechanisms.

Cholesterol has been immobilized on Sepharose-6B via oxyether linkages to the 3- or 25-position. The 3- or 25-hydroxysterol methanesulfonates were coupled with epoxy-Sepharose-6B at 80 degrees C for 24 h. Approximately 2% of the ligand was incorporated into the gel. These types of affinity columns may be useful in purifying proteins that specifically bind or metabolize cholesterol.

We tested the hypothesis that breast or formula feeding and cholesterol intake during the neonatal period influence cholesterol metabolism and arterial fatty streaks in young adult baboons. Genetic variation was controlled by randomly assigning half-sib sire progeny to a factorial dietary design. We measured serum cholesterol and lipoprotein cholesterol concentrations enzymically and cholesterol production and bile acid excretion rates isotopically. The bile cholesterol saturation index was calculated from enzymic analyses of cholesterol, bile salt and phospholipid concentrations in gallbladder bile. Breast-fed baboons had higher serum VLDL + LDL cholesterol/HDL cholesterol ratios in the early postweaning period (six months) until adulthood (7-8 years) than formula-fed baboons. In adulthood a high cholesterol diet increased bile acid excretion by approximately 40% in formula-fed baboons but did not significantly increase the bile acid excretion rate among breast-fed animals. Adult baboons breast fed as infants also had an approximately 8% lower cholesterol production rate than formula-fed animals and a 20% higher bile cholesterol saturation index. The level of cholesterol in the infant formulas influenced cholesterol metabolism in adulthood but not serum lipoprotein concentrations. As young adults, breast-fed baboons had more extensive arterial fatty streaks than formula-fed baboons. This difference could be accounted for by differences in the lipoprotein ratios. These results demonstrate that breast and formula feeding differentially modify cholesterol metabolism. This may influence the development of chronic diseases.

We tested the hypothesis that infant cholesterol intake and breast- versus formula-feeding influence the bile cholesterol saturation index and bile acid conjugate composition in adult baboons at 7-8 years of age. We also measured the influence of the postweaning intake of dietary cholesterol and fat (saturated and unsaturated) on the effects of the infant diets. The 80 baboons were derived from six sires and 80 dams and randomly assigned at birth to breast-feeding or to one of three formulas containing about 2, 30, or 60 mg cholesterol/dl. After weaning at 16 weeks of age the animals were assigned to one of four adult diets, which contained 0.01 or 1.0 mg/kcal of cholesterol containing 40% of calories from saturated or unsaturated fat. The bile cholesterol saturation index was significantly higher at 7-8 years of age in baboons breast-fed as infants compared with those fed formula (87.0% versus 72.8%, p less than 0.004). The cholesterol saturation index was not significantly different among the three formula groups. Among baboons who were breast-fed and subsequently fed saturated fat as adults, the glycine/taurine (G/T) ratios of the bile acid conjugates were about three times those of baboons fed unsaturated fat (1.53 versus 0.47); whereas among formula-fed animals the type of fat did not influence the G/T ratio (interaction, p = 0.022). Adult baboons fed the three formulas in infancy had an inverse relationship of the G/T ratio to the level of formula cholesterol (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

We tested the hypothesis that preweaning diet alters cholesterol metabolism in adult baboons. Eighty baboons, progeny of 6 sires and 80 dams, were either breast-fed or fed one of three infant formulas containing 2, 30 or 60 mg cholesterol/100 mL. At 16 wk of age the baboons were weaned to one of four diets containing 1.0 or 0.01 mg cholesterol/kcal with 40% of energy from saturated [polyunsaturated fat/saturated fat [P/S) = 0.37] or unsaturated fat [P/S = 2.1] and maintained on these diets until they were necropsied as young adults at 7-8 yr of age. We observed no significant effects of formula cholesterol content on serum lipid or lipoprotein concentrations measured at 6-8 yr of age, but formula cholesterol intake influenced the cholesterol turnover rate and several variables of cholesterol metabolism in the adult. At 6-8 yr, baboons that were breast-fed during infancy, compared with those that were formula-fed, had lower high-density lipoprotein cholesterol (HDL-C) concentrations and higher ratios of very-low-density plus low-density lipoprotein cholesterol (VLDL + LDL-C) to HDL-C. Breast-fed baboons, as adults, had lower cholesterol production rates, masses of the rapidly exchanging cholesterol compartment (pool A) and neutral steroid excretion rates than did those fed formula as infants. Breast and formula feeding differentially influenced the adult metabolic responses to dietary cholesterol or fat saturation. These results demonstrate that breast vs. formula feeding in infancy alters cholesterol metabolism and serum lipoprotein concentrations in adult baboons.

An agar medium containing 5% cholesterol has been developed for the isolation, enumeration, and characterization of cholesterol-reducing strains of Eubacterium.

We examined the results of one generation of selection for serum cholesterol (SC) concentration on low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and triglyceride concentrations and weight in baboons (Papio cynocephalus). Parents of two lines (high SC response and low SC response) were chosen based on their SC response to a 4-month challenge with a cholesterol and saturated fat enriched diet. Parents of the control line were chosen without regard for SC levels. Expression of SC, LDL-C, and HDL-C concentrations was moderately influenced by additive genetic effects as evidenced by the direct and correlated responses of the serum lipoprotein concentrations of the juvenile offspring of the three lines. Realized heritability of SC and genetic correlations of SC with LDL-C and HDL-C were moderate to high. Sex and age were important factors influencing expression of SC, LDL-C, HDL-C, triglycerides, and weight in both adult baboons and their offspring.

5 alpha-Cholest-8(14)-en-3 beta-0l-15-one has been found to have significant hypocholesterolemic action on oral administration to baboons at dosages of 50 and 75 mg/kg of body weight. The 15-ketosterol decreased the levels of total serum cholesterol and low density lipoprotein plus very low density lipoprotein (LDL/VLDL) cholesterol and the percentage of total cholesterol associated with LDL/VLDL and increased the percentage of total cholesterol associated with high density lipoprotein (HDL). Moreover, administration of the steroid was associated with an absolute increase in the concentration of HDL cholesterol in those animals with low HDL levels (or with a low percentage of total serum cholesterol in the HDL fraction.

For 26 months, we fed baboons a high saturated fat, high cholesterol diet that contained very low concentrations of four common pesticides (chlordane, parathion, diazinon, and carbofuran). We detected no effect of pesticides on body weight, serum lipid, or lipoprotein cholesterol concentrations, or experimental atherosclerosis. We then examined the associations of serum lipid and lipoprotein cholesterol concentrations (predictor variables) with arterial lesions (response variables). Among predictor variables, very low density lipoprotein plus low density lipoprotein cholesterol concentration showed a positive association with fatty streaks in the aorta and its major branches, including the coronary arteries, while high density lipoprotein cholesterol concentration showed a consistently negative association. The very low density lipoprotein plus low density lipoprotein/high density lipoprotein cholesterol ratio was more highly associated with lesions than was either value alone. These results are consistent with epidemiologic evidence suggesting that high density lipoprotein cholesterol concentration is inversely related to probability of developing clinically manifest atherosclerotic disease.

After oral administration of a mixture of [1,2(n)-3H]cholesterol and [4-14C]cholesterol to a baboon, fecal coprostanone had a 46% lower 3H/14C ratio than the dose administered. Loss of 3H by enolization of the 3-ketone could account for the decrease in 3H/14C. If [7(n)-3H]cholesterol was administered instead of [1,2(n)-3H]cholesterol a 23% loss of 3H from coprostanone was found. Procedures requiring measurement of 3H-coprostanone derived from [1,2(n)-3H]- or [7(n)-3H]cholesterol could be seriously in error unless an appropriate correction for loss of 3H is made.

A plasmalogen, plasmenylethanolamine, is required for in vitro growth of strains of Eubacterium which convert cholesterol to coprostanol. Plasmenylethanolamine was isolated from calf brain by selective saponification of lipid fractions separated by thin-layer or column chromatography. Cholesterol-containing thioglycolate broth plus purified plasmenylethanolamine or its 2-lyso derivative supported growth of Eubacterium ATCC 21408 and a cholesterol-reducing Eubacterium isolated from baboon feces. Plasmenylethanolamine obtained from commercial sources also supported growth of these organisms, but none of a number of other pure lipids would support growth. Metabolism of the alkenyl ether group of plasmenylethanolamine occurred during growth.

Six male and 134 female adult baboons were assigned to high or low lines on the basis of response of total serum cholesterol concentration to a high cholesterol, high saturated fat diet. Positive assortative mating of these breeders produced 36 high-line and 42 low-line progeny, of which 30 high-line and 39 low-line progeny survived to one year of age. The mean serum cholesterol concentrations of the progeny produced in the two lines were significantly different at all ages from birth to one year. The serum cholesterol levels at birth were not strongly correlated with subsequent levels, but those after 3 weeks were highly correlated with one another. Heritability of total serum cholesterol concentration was estimated by realized heritability, correlation coefficients between parent and progeny values, and by regression coefficients of progeny values on mid-parent value. Estimates of heritability of serum cholesterol level at birth were low, but from 3 weeks to one year of age they ranged from 0.25 to 0.80 and averaged about 0.45. There was a correlated response of HDL and LDL cholesterol levels at one year to selection for total serum cholesterol.

The long-term effects of infant diet (breast milk or formula containing 2, 30, or 60 mg/dl cholesterol) and subsequent dietary cholesterol (1 mg/kcal) and fat (saturated or unsaturated) on serum lipid and apolipoprotein concentrations were estimated using 82 juvenile baboons 4-6 years of age. A significant interaction of infant diet (breast vs formula) with type of fat (saturated vs unsaturated) at 4-6 years of age was observed on HDL cholesterol and apolipoprotein A-I (apoA-I) concentrations. That is, animals breast-fed as infants had higher HDL cholesterol and apoA-I concentrations when fed unsaturated fat from weaning to 4-6 years of age than those fed saturated fat (77 vs 68 mg/dl). In contrast, animals fed formulas in infancy followed by a diet containing unsaturated fat had lower HDL cholesterol and apoA-I concentrations at 4-6 years of age than did those fed saturated fat (67 vs 78 mg/dl). However, breast feeding or feeding formulas containing various levels of cholesterol for 3 months during infancy did not result in statistically significant differences in total serum cholesterol, VLDL + LDL cholesterol and apolipoprotein B (apoB) concentrations. Dietary cholesterol after infancy significantly increased serum total cholesterol, VLDL + LDL and HDL cholesterol, apoA-I and apoB concentrations. All of these response variables also were higher in animals fed saturated fat compared to those fed unsaturated fat on the same level of cholesterol. At 4-6 years of age, regardless of diet, females had significantly higher serum VLDL + LDL cholesterol (57 vs 43 mg/dl) and apoB concentrations (39 vs 30 mg/dl) than did males.

Positive assortative mating of baboons (Papio sp.) based on elevation of serum cholesterol concentrations in response to a cholesterol- and saturated fat-enriched diet produced 64 progeny (30 high line; 34 low line). When the animals were 3 to 4 years of age, we tested their lipoprotein cholesterol responses to dietary cholesterol and fat in a factorial experiment with two levels of dietary cholesterol (1.7 and less than 0.01 mg/kcal) and two types of fat, coconut oil (P/S 0.1) and corn oil (P/S 3.5), each providing 40% of total calories from fat; we also tested their responses to chow. The high line animals had significantly higher very low density plus low density lipoprotein (VLDL + LDL) and high density lipoprotein (HDL) cholesterol levels on all diets. The effects of dietary cholesterol on VLDL + LDL cholesterol concentrations were greater in high line animals than in low line animals, but dietary cholesterol's effects on HDL cholesterol were similar in both lines. The effects of saturated fat, compared to unsaturated fat, on both VLDL + LDL and HDL cholesterol levels were similar in both lines. Selective breeding produced lines diverging in lipoprotein cholesterol concentrations by acting on several different genetically mediated processes that control serum lipoprotein levels. At least one of these processes involves responsiveness of serum VLDL + LDL cholesterol concentration to dietary cholesterol.

Genetic effects on serum lipoprotein and apoprotein concentrations were investigated using a paternal half-sib design with 79 progeny of 6 sires. Significant differences (P less than 0.05) were observed among sire progeny groups at 4-6 years of age for serum cholesterol, HDL cholesterol and apoA-I concentrations. A sire effect (P less than 0.10) also was observed for VLDL + LDL cholesterol concentrations, but differences were not observed (P greater than 0.10) among sire progeny groups for apoB concentrations. Estimates of heritability were 0.54 for serum cholesterol, 0.32 for VLDL + LDL cholesterol, 0.78 for HDL cholesterol, 0.56 for apoA-I, and 0.20 for apoB concentration. Genetic (rg) and environmental (re) correlations among serum cholesterol, lipoprotein cholesterol, and apoprotein concentrations were positive except for the negative genetic relationships of apoA-I with apoB (rg = -0.74) and with VLDL + LDL cholesterol (rg = -0.30) concentrations. The phenotypic correlation (rp = 0.31) of VLDL + LDL cholesterol with HDL cholesterol was due entirely to the genetic contribution (0.31) since the environmental contribution was zero. The positive genetic relationship (rg = 0.62) of VLDL + LDL cholesterol and HDL cholesterol may be due to biochemical mechanisms controlling cholesterol turnover since the genetic correlations of VLDL + LDL cholesterol and HDL cholesterol with cholesterol turnover rate were both negative (-0.43 and -0.68, respectively). A strong negative genetic correlation (rg = -0.95) was observed between apoA-I and cholesterol turnover, a finding that suggests a close physiologic relationship between these variables.

We characterized two isolates of cholesterol-reducing Eubacterium by conducting conventional biochemical tests and by testing various sterols and glycerolipids as potential growth factors. In media containing cholesterol and plasmenylethanolamine, the tests for nitrate reduction, indole production, and gelatin and starch hydrolyses were negative, and no acid was produced from any of 22 carbohydrates. Both isolates hydrolyzed esculin to esculetin, indicating beta-glycosidase activity. In addition to plasmenylethanolamine, five other lipids which contain an alkenyl ether residue supported growth of Eubacterium strain 403 in a lecithin-cholesterol base medium. Of six steroids tested, cholesterol, cholest-4-en-3-one, cholest-4-en-3 beta-ol (allocholesterol), and androst-5-en-3 beta-ol-17-one supported growth of Eubacterium strain 403. All four steroids were reduced to the 3 beta-ol, 5 beta-H products. The delta 5 steroids cholest-5-en-3 alpha-ol (epicholesterol) and 22,23-bisnor-5-cholenic acid-3-beta-ol were not reduced and did not support growth of the Eubacterium strain.

One hundred three baboon infants, the progeny of an equal number of dams and seven sires, were breast fed or were fed prepared formulas containing 1.2, 29, or 61 mg/dl cholesterol for 14 weeks. We measured serum cholesterol and triglyceride concentrations at birth and at 3-week intervals, and cholesterol absorption at 12 weeks. Dietary cholesterol had a significant effect on serum cholesterol concentration at 12 weeks and on cholesterol absorption, but did not affect weight or serum triglyceride concentration. Sire had a significant effect on serum cholesterol concentration at birth and at 12 weeks, but the effect at birth did not predict the effect at 12 weeks. Sire did not affect cholesterol absorption, serum triglyceride concentration, or weight at 12 weeks. The sire effect on serum cholesterol concentration in infancy is not mediated by control of cholesterol absorption. Males weighed more than females at 12 weeks, but sex did not affect serum cholesterol concentration, triglyceride concentration, or cholesterol absorption.

Genetic effects on serum high density lipoprotein (HDL) cholesterol concentration and several parameters of a two-pool model of cholesterol metabolism were investigated in 79 baboons, the progeny of 6 sires. Significant differences (P less than 0.05) were observed among the sire progeny groups for HDL cholesterol (HDL-C), cholesterol production rate, cholesterol mass of pool A, and the rate constants KA and KAB. Rank correlations (rs) revealed that the sire progeny group means for HDL-C are closely correlated with those for the cholesterol mass of pool A (rs = 0.89), KA (rs = -0.78), and KAB (rs = -0.94). These strong correlations suggest that pool A, KA, and KAB are influenced to a large degree by the same genes that regulate HDL-C concentration. The strong inverse relationship (rs = -0.78) between HDL-C and KA suggests that the differences among these sire progeny groups for HDL-C are due chiefly to those metabolic processes which regulate cholesterol excretion from pool A. This conclusion is consistent with reports that HDL-C is a preferred precursor for bile acid synthesis.

The deferred effects of infant diets and the effects of juvenile diets on cholesterol metabolism were estimated in 83 baboons (Papio sp.) at 3.5 years of age. As infants, the animals were breast-fed or fed one of three formulas containing approximately 2, 30, or 60 mg/dl cholesterol. After weaning at 14 weeks of age, the animals were fed one of four juvenile diets high or low in cholesterol with saturated (P/S = 0.37) or unsaturated (P/S = 2.1) fats. Cholesterol absorption and cholesterol turnover were measured by fecal isotopic methods, and variables of cholesterol metabolism were estimated from a two-pool model. Among juvenile animals breast-fed during infancy, the percentage of cholesterol absorption was higher, while the fluxes of cholesterol from Pool A (QAA, QA, and QAB) and the cholesterol mass of Pool B were lower, compared to those fed formulas. The level of cholesterol in formulas fed during infancy did not influence cholesterol metabolism during the juvenile period. During the juvenile period, saturated fat significantly decreased the cholesterol production rate (QA) and increased the rate constants for cholesterol flux between Pool A and Pool B (KAB and KBA) compared to unsaturated fat. High cholesterol intake increased bile acid and neutral steroid excretion, cholesterol turnover rate, the mass of Pool A, and the rate constant KA and fluxes QA and QAA for removal of cholesterol from Pool A. However, KAB, t1/2 B (half-time of Pool B), and the percentage of cholesterol absorbed were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

We isolated and characterized nine new strains of cholesterol-reducing bacteria from feces and intestinal contents of baboons. Cholesterol-brain agar was used for the primary isolation, and subsequent biochemical tests were done in a lecithin-cholesterol broth containing plasmenylethanolamine and various substrates. All strains had similar colony and cell morphology, hydrolyzed the beta-glucosides esculin and amygdalin, metabolized pyruvate, and produced acetate and acetoin. Unlike previously reported strains, the nine new strains did not require cholesterol and an alkenyl ether lipid (e.g., plasmalogen) for growth; however, only two strains reduced cholesterol in the absence of the plasmalogen. These two strains also produced succinate as an end product. Carbohydrate fermentation was variable; some strains produced weak acid (pH 5.5 to 6.0) from only a few carbohydrates, whereas other strains produced strong acid reactions (pH less than or equal to 5.5) from a wide variety of carbohydrates.

Cholesterol turnover was studied in four baboons by injecting [14C]cholesterol 186 days and [3H]cholesterol 4 days before necropsy, and fitting a two- or three-pool model to the resulting specific activity-time data. At necropsy, cholesterol mass and specific activity were determined for the total body (minus the central nervous system) and for many tissues. A pool model permits the estimation, from the plasma specific activity-time curve alone, of total body cholesterol within a limited range, depending upon the extent of side pool synthesis. The principal aim of this study was to estimate the extent of cholesterol synthesis in the side pools of the model, by computing the amount of side pool synthesis needed to equal the measured total body cholesterol. Central pool synthesis varied from 61 to 89% of the total cholesterol production rate. Thus, approximately 25% (11 to 39%) of the production rate arose from peripheral (pool 3 for the three-pool, and pool 2 for the two-pool model) cholesterol synthesis. Moreover, the finding that the measured total body cholesterol fell within the range obtained from the kinetic analysis by using reasonable assumptions (namely, that zero or that half the production rate occurred in the side pools), provides evidence for the physiological validity of the model. A second aim of this study was to explore cholesterol turnover in various tissues. A pool model predicts that rapidly turning over tissues will have higher specific activities at early times and lower specific activities at later times after injection of tracer relative to slowly turning over tissues, except where significant synthesis occurs. Tissues were ranked 1 to 17 for 3H and 17 to 1 for 14C cholesterol specific activity values. Except for the GI tract and testis, the tissues had similar ranks for both 3H and 14C, further validating model predictions. Results in all four baboons were similar. Turnover rates for the different tissues loosely fell into three groups which were turning over at fast, intermediate, and slow rates. Finally, the magnitude of variation of cholesterol specific activity was moderate for several distributed tissues (fat, muscle, arteries, and the alimentary tract), but was small for liver. Cholesterol turnover in serial biopsies of skin, muscle, and fat could, however, be fitted with a single pool to estimate tissue turnover rates.

We estimated the effects of age, sex, saturated and polyunsaturated dietary fat, and two levels of dietary cholesterol intake on cholesterol absorption in juvenile baboons between 15 and 51 months of age. We compared the reproducibility of methods of measuring cholesterol absorption within animals, and also compared estimates of percentage cholesterol absorption by three different methods. Cholesterol absorption was significantly greater in all diet groups at 27 and 39 months of age than it was at 15 or 51 months (P < 0.001). Cholesterol absorption (%) was significantly greater in animals fed low cholesterol diets than it was in animals fed high cholesterol diets. However, cholesterol absorption was not affected by type of fat (saturated or unsaturated) in the diet or by sex. The range of reproducibility (within-animal standard deviation) of percentage cholesterol absorption for different diet groups was 3.35 to 3.90% for the Borgström method (1969. J. Lipid Res. 10: 331--337), 4.67 to 7.30% for the Sodhi method (1971. Proc. Soc. Exp. Biol. Med. 137: 277-279), and 3.69 to 7.15% by a combined isotopic chromatographic method (Method I). Percentage absorption measured by either the Sodhi method or Method I was significantly greater than that measured by the Borgström method.