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Background: The acute phase response (APR) represents a systemic counterpart to the localized inflammatory response. This report describes patient-oriented and non-human primate model studies to determine the effect of periodontal disease on systemic acute phase proteins (APP)., Methods: Patient-oriented studies included comparison of the levels of APP, using enzyme-linked immunosorbent assay (ELISA), with the presence and severity of periodontitis in localized chronic periodontitis (LCP), generalized aggressive periodontitis (GAP), and Sjogren's syndrome (SS) patients. The non-human primate experiments evaluated the serum level of APPs under natural conditions, following mechanical hygiene, experimental gingivitis, and during ligature-induced periodontitis., Results: Analysis of the LCP population showed what appeared to be a threshold of periodontal disease severity required for elevating the C-reactive protein (CRP) and haptoglobin (HG). The results demonstrated a significant elevation in CRP in the GAP versus the control groups, as well as lower levels of all mediators in healthy non-smokers (HNS) versus smokers (HS), suggesting that these systemic inflammatory markers were altered in response to challenge by noxious materials from smoking. Significantly different levels of CRP, HG, and alpha1-antiproteinase were noted in the SS patients suggesting that the autoimmune aspects of Sjögren's syndrome may impact upon oral health and systemic responses. Parallel evidence was also obtained from the primate studies. Providing mechanical oral hygiene, which significantly lowered clinical inflammation and bleeding of the gingiva, decreased the serum APP levels. Both CRP and fibrinogen were significantly elevated during progressing periodontitis, which also appeared to have an impact on serum lipids and lipoproteins., Conclusions: These findings supported results relating chronic oral infections and the inflammation of periodontitis as contributors to and/or triggers for systemic inflammatory responses. Finally, similarities in the clinical and microbiological parameters of gingival inflammation and periodontitis between humans and non-human primates was extended to identification of changes in serum APP in the non-human primates that appeared to be in direct response to the induction of progressing periodontitis. These systemic changes provide additional evidence for the biological plausibility of periodontal infections contributing to various systemic diseases.

The relationship between food availability and metabolic physiology was studied in groups of free-ranging baboons (Papio spp.) living in the Amboseli National Park and the Masai Mara National Reserve of Kenya. Three groups subsisted entirely on natural forage, while two other groups lived near tourist facilities and often consumed food wastes from these lodges. The refuse provided a very accessible food source with relatively high caloric density. Consumption of the refuse was associated with reduced locomotion. Sexually mature individuals from all five groups were sedated surreptitiously in the early morning and blood samples were collected. Compared to animals foraging exclusively in the wild, animals that supplemented their diet with the refuse items had two- to threefold elevations in serum insulin concentrations, as well as increased total cholesterol (C), HDL-C, and VLDL+LDL-C levels. No sex differences in physiological measures were observed except in body mass. Elevated serum insulin, and cholesterol and lipoprotein concentrations influence the development of cardiovascular disease and have been shown to be subject to dietary manipulation and exercise under controlled conditions. The present results suggest potentially deleterious effects of a highly accessible, calorically dense food source, and associated reduction of physical activity for baboons living in an otherwise natural environment., (Copyright 2002 Wiley-Liss, Inc.)

26-Hydroxycholesterol (26OHC), a major oxysterol in human blood, is believed to play an important role in reverse cholesterol transport, bile acid formation, and regulation of various cellular processes. Using isotope dilution mass spectrometry, we measured plasma 26OHC concentrations in baboons fed either a high cholesterol/saturated fat (HC-SF) or normal chow diet. Plasma 26OHC levels in baboons were comparable to those reported for humans and were positively correlated with plasma cholesterol concentrations. Animals on the HC-SF diet had significantly higher 26OHC levels (0.274+/-0.058 microM, mean+/-S.D.) than those on the chow diet (0.156+/-0.046 microM). In separate experiments, [(3)H]26OHC was injected into four tethered baboons, and multiple blood samples drawn over a 1-h period were analyzed for [(3)H]26OHC and 26OHC. Fitting the specific radioactivity data to a two-pool compartmental model indicated a rapidly turning over plasma compartment (t(1/2) 2.9-6.0 min) and a second compartment with slow turnover (t(1/2) 76-333 min). The calculated 26OHC production rate was 2.5 micromol/kg body weight/day. Assuming all 26OHC is converted to bile acids, the 26OHC production rate corresponds to about 10% of total bile acid production in adult baboons. These results indicate that rapid turnover of plasma 26OHC at submicromolar concentrations could significantly contribute to bile acid synthesis.

Hepatic cholesterol 7alpha-hydroxylase (CYP7A) and sterol 27 hydroxylase activities were measured in fetal, newborn, suckling, and weaned piglets from 76 d into gestation to 49 d of age. Hepatic CYP7A activity was not detected in fetal microsomes, but it increased to 6.8 +/- 2.6 pmol/min x mg(-1) protein in suckling piglets at 21 d of age and to 18.2 +/- 2.5 in weaned piglets at 49 d of age. Hepatic CYP7A activity was not different between 49-d-old piglets weaned at 21 d and piglets suckled for 49 d (18.9 +/- 2.6 and 18.2 +/- 2.5 pmol/min x mg protein, respectively). Fasting for 14 h decreased CYP7A activity by 86% in both suckled and weaned piglets. Cholesterol 7alpha-hydroxylase activity remained decreased for at least 5 h after refeeding. Sterol 27-hydroxylase activity was also undetectable near birth, but was detectable by 21 d of age. Postnatally, sterol 27-hydroxylase activity was not influenced by age or suckling and weaning, as was CYP7A. Sterol 27-hydroxylase was decreased by 80% in piglets deprived of feed compared with piglets given free access. In contrast to CYP7A activity, 27-hydroxylase activity returned within 5 h after refeeding to levels observed in piglets given ad libitum access to feed. Similar to CYP7A enzyme activity, hepatic CYP7A mRNA was not detected in newborn piglets, but increased from 2.7 +/- 1.7 pg mRNA/microg RNA in suckling piglets at 21 d to 13.7 +/- 1.2 in 49-d-old piglets weaned at 21 d. As with enzyme activity, feed deprivation decreased CYP7A mRNA to barely detectable levels (< .5 pg/microg RNA), and which remained decreased for at least 5 h following refeeding (.6 +/- .3 and 2.67 +/- .4 pg mRNA/microg RNA for suckled and weaned piglets, respectively). In piglets allowed free access to feed, CYP7A mRNA concentrations were associated positively (P = .001) with enzyme activity. These results suggest that developmental regulation of CYP7A activity is the result of a pretranslational mechanism.

The HMG-CoA reductase inhibitor, lovastatin, blocks targeting of the Rho and Ras families of small GTPases to their active sites by inhibiting protein prenylation. Control NIH3T3 cells, and those overexpressing human cyclin E protein were treated with lovastatin for 24 h to determine the effects of cyclin E overexpression on lovastatin-induced growth arrest and cell rounding. Lovastatin treatment (10 microM) of control 3T3 cells resulted in growth arrest at G1 accompanied by actin stress fiber disassembly, cell rounding, and decreased active RhoA from the membranous protein fraction. By contrast, in NIH3T3 cells overexpressing cyclin E, lovastatin did not cause loss of RhoA from the membrane (active) protein fraction, actin stress fiber disassembly, cell rounding or growth arrest within 24 h. Analysis of cell cycle proteins showed that 24 h of lovastatin treatment in the control cells caused an elevation in the levels of the cyclin-dependent kinase inhibitor p27(kip1), inhibition of both cyclin E- and cyclin A-dependent kinase activity, and decreased levels of hyperphosphorylated retinoblastoma protein (pRb). By contrast, lovastatin treatment of the cyclin E overexpressors did not suppress either cyclin E- or cyclin A-dependent kinase activity, nor did it alter the level of maximally phosphorylated pRb, despite increased levels of p27(kip1). However, by 72 h, the cyclin E overexpressors rounded up but remained attached to the substratum, indicating a delayed response to lovastatin. In contrast with lovastatin, inactivation of membrane-bound Rho proteins (i.e., GTP-bound RhoA, RhoB, RhoC) with botulinum C3 transferase caused cell rounding and G1 growth arrest in both cell types but did not inhibit cyclin E-dependent histone kinase activity in the cyclin E overexpressors. In addition, 24 h of cycloheximide treatment caused depletion of RhoA from the membrane (active) fraction in neo cells, but in the cells overexpressing cyclin E, RhoA remained in the active (membrane-associated) fraction. Our observations suggest that (1) RhoA activation occurs downstream of cyclin E-dependent kinase activation, and (2) overexpression of cyclin E decreased the turnover rate of active RhoA., (Copyright 1999 Wiley-Liss, Inc.)

Prostate cancer cells derived from transgenic mice with adenocarcinoma of the prostate (TRAMP cells) were treated with the HMG-CoA reductase inhibitor, lovastatin. This caused inactivation of the small GTPase RhoA, actin stress fiber disassembly, cell rounding, growth arrest in the G1 phase of the cell cycle, cell detachment and apoptosis. Addition of geranylgeraniol (GGOL) in the presence of lovastatin, to stimulate protein geranylgeranylation, prevented lovastatin's effects. That is, RhoA was activated, actin stress fibers were assembled, the cells assumed a flat morphology and cell growth resumed. The following observations support an essential role for RhoA in TRAMP cell growth: (1) TRAMP cells expressing dominant-negative RhoA (T19N) mutant protein displayed few actin stress fibers and grew at a slower rate than controls (35 h doubling time for cells expressing RhoA (T19N) vs 20 h for untransfected cells); (2) TRAMP cells expressing constitutively active RhoA (Q63L) mutant protein displayed a contractile phenotype and grew faster than controls (13 h doubling time). Interestingly, addition of farnesol (FOL) with lovastatin, to stimulate protein farnesylation, prevented lovastatin-induced cell rounding, cell detachment and apoptosis, and stimulated cell spreading to a spindle shaped morphology. However, RhoA remained inactive and growth arrest persisted. The morphological effects of FOL addition were prevented in TRAMP cells expressing dominant-negative H-Ras (T17N) mutant protein. Thus, it appears that H-Ras is capable of inducing cell spreading, but incapable of supporting cell proliferation, in the absence of geranylgeranylated proteins like RhoA.

We investigated dietary effects on pleiotropic relationships among 3 HDL cholesterol (C) subfractions (HDL1-C, HDL2-C, and HDL3-C; levels quantified by gradient gel electrophoresis) for 942 pedigreed baboons (Papio hamadryas) who were fed a basal (Chow) diet and a high cholesterol, saturated fat (HCSF) challenge diet. Using multivariate maximum likelihood methods we estimated heritabilities for all 6 traits, genetic and environmental correlations (rhoG and rhoE) between them, and the additive genetic variance of each subfraction's response to the diets. On the Chow diet, genetic correlations between the 3 subfractions were significant, and we observed complete pleiotropy between HDL1-C and HDL3-C (rhoG=-0.81). On the HCSF diet, only the genetic correlation between HDL1-C and HDL3-C (rhoG=-0.61) was significant. Genetic correlations between individual subfractions on the Chow and HCSF diets did not differ significantly from 1.0, indicating that the same additive genes influenced each subfraction's levels regardless of diet. However, the additive genetic variance of response to the diets was highly significant for HDL1-C and HDL2-C, but not for HDL3-C. Similar sets of genes influence variation in the 3 HDL subfractions on the Chow diet, and the same set influences variation in each subfraction on the HCSF diet. However, the expression of genes influencing HDL1-C and HDL2-C is altered by the HCSF diet, disrupting the pleiotropy observed between the 3 subfractions on the Chow diet.

Lovastatin, an inhibitor of protein prenylation, was reported to inhibit DNA synthesis and induce apoptosis in cultured cells. This report describes the morphological consequences of lovastatin treatment. Lovastatin (50 microM) induced mesangial cell rounding and disassembly of actin stress fibers within 24 to 48 h. After 48 to 72 h of lovastatin treatment, the cells detached from the substratum and underwent apoptotic cell death as evidenced by condensed nuclear chromatin, nuclear fragmentation, cell blebbing and decrease in cell size. Time lapse cinematography revealed that lovastatin caused cell rounding by either inhibiting cytokinesis or cell spreading following cytokinesis. Lovastatin-induced cell rounding, detachment, and apoptosis were dependent upon cell proliferation. These effects were prevented by serum deprivation to inhibit cell proliferation or by plating cells at densities which resulted in contact inhibition of cell growth. Lovastatin-induced mesangial cell rounding and apoptosis were also prevented by the inclusion of the isoprenoids all-trans-farnesol or all-trans-geranylgeraniol in the incubation medium. These results indicate that the effects of lovastatin were mediated by inhibition of protein isoprenylation because exogenous all-trans-geranylgeraniol can be used only in protein prenylation. The small GTP-binding protein RhoA, which may be important for cell spreading and cytokinesis, accumulated in the cytosol following treatment with lovastatin, suggestive of its inactivation. This effect was also prevented by the inclusion of either farnesol or geranylgeraniol in the incubation medium. Thus, lovastatin-induced apoptosis in mesangial cells occurs by interfering with prenylation dependent mitotic and post-mitotic events.

We tested the hypothesis that breast- and formula-feeding of infant baboons affect postweaning plasma thyroid hormone concentrations and that differences in thyroid hormone concentrations are associated with long-term effects of infant diet on lipoprotein concentrations and cholesterol metabolism. Newborn baboons were breast-fed (n = 12) or fed formulas with a high polyunsaturated/saturated (P/S) fat ratio (n = 11) or with a low P/S ratio (n = 12) similar to baboon breast milk. Baboons were weaned at 14 weeks of age to a high cholesterol, saturated fat diet. Plasma thyroid hormone concentrations were measured in this group of baboons until about 223 weeks of age. Thyroid hormones were also measured at 400 weeks in a second group of adult baboons (n = 80) that as infants were either breast-fed or fed formulas with varying levels of cholesterol. Baboons breast-fed as infants averaged 11% higher (P < 0.03) thyroxine (T4) concentrations from 34 to 400 weeks of age compared with those fed formulas. From 70 to 400 weeks of age breast-fed baboons had 10% lower T3/T4 ratios (P < 0.03). Breast- versus formula-feeding did not affect postweaning T3 and fT3 concentrations. Postweaning thyroid hormone concentrations were not significantly affected by the P/S ratio or the cholesterol level of the infant formulas. The rank correlation of the means of the sire progeny groups for T4 and HDL-C concentrations was statistically significant (rn = -0.83; P < 0.05). Partial correlations of T4 concentrations with body weight, feed intake, or measures of cholesterol metabolism were not significant. T4 concentrations were significantly correlated with T3 concentrations (r = 0.42; P < 0.02), and T3 concentrations were correlated with bile acid synthesis rate (r = 0.47; P < 0.01), acyl-CoA cholesterol acyltransferase (r = 0.66; P < 0.001), and plasma HDL1-C levels (r = -0.49; P < 0.007). These effects suggest that altered thyroid hormone homeostasis may partially mediate the long-term differences in cholesterol metabolism caused by breast-versus formula-feeding.

We tested the hypothesis that triiodothyronine (T3) treatment accelerates the early postnatal maturation of bile acid metabolism in the baboon. Infant baboons were implanted with 21-day-release pellets containing T3 (n = 12), a placebo pellet (n = 6), or no pellet (n = 13). T3 treatment increased plasma T3 concentrations from 3.0 to 5.0 nmol/l between birth and 15 wk of age. At 15 wk of age, bile acid pool sizes, fractional turnover rates (FTR), and synthetic rates were determined by an isotope-dilution method with 3H- and 14C-labeled cholic (CA) and chenodeoxycholic acid (CDCA). T3 treatment increased CA pool size by 47% and CA synthetic rate by 37% but did not significantly affect CDCA pool size or synthetic rate. Consequently CA-to-CDCA pool size ratio (0.77 vs. 0.42) and biliary CA-to-CDCA concentration ratio (0.88 vs. 0.46) were higher in the T3-treated infants than in combined placebo-treated and nontreated control infants. T3 treatment did not affect the bile acid glycine-to-taurine conjugate ratio, CA FTR, or CDCA pool size, FTR, and synthetic rate. T3 treatment lowered plasma high-density lipoprotein fraction 2 and 3 cholesterol concentrations by 22 and 40%, respectively. T3 treatment also increased hepatic low-density lipoprotein receptor mRNA levels but did not affect plasma low-density lipoprotein cholesterol concentrations. We conclude that modest elevation of plasma T3 during the preweaning period increases the CA-to-CDCA ratio at the end of the preweaning period to near adult values.

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)

We tested, with 14-wk-old baboons before weaning, the hypothesis that bile acid metabolism is differentially affected by breast feeding or by feeding formulas with a high polyunsaturated:saturated fatty acid ratio or with a low ratio, similar to that of breast milk. Bile lipid content, bile acid pool size, fractional turnover rate, synthetic rate and conjugate composition were measured in a single bile sample 9 d after an injection on d 1 of a mixture of [14C]cholic and [14C]chenodeoxycholic acids and an injection of a mixture of [3H]cholic acid and [3H]chenodeoxycholic acid on d 8. The principal biliary bile acid was chenodeoxycholic acid. The only difference in chenodeoxycholic acid metabolism among the infant diet groups was a lower chenodeoxycholic acid synthetic rate in baboons fed the low polyunsaturated:saturated formula compared with those fed the high polyunsaturated:saturated formula or breast-fed. Cholic acid metabolism was significantly affected by infant diet: breast-fed infants had a smaller cholic acid pool size, lower cholic acid percentage of total bile acids, higher cholic acid glycine:taurine conjugate ratio and larger cholic acid fractional turnover rate than formula-fed animals. The polyunsaturated:saturated fatty acid ratio in the formulas did not significantly affect these variables. These results show that differences in bile acid metabolism between breast- and formula-fed infant baboons are limited principally to cholic acid. These differences likely are due to factors other than fatty acid saturation.

Various protein isoforms have been identified for human apolipoprotein A-IV (apoA-IV). However, investigations of their physiological effects have been limited because of low frequencies for many of the apoA-IV variants. Recent discovery of extensive variation in baboon apoA-IV using isoelectric focusing (IEF) makes this primate species an excellent model for genetic studies of apoA-IV. In this study, the molecular basis for net charge differences between two common apoA-IV isoforms (I and E) was determined by cloning and sequencing of intestinal cDNAs from homozygous baboons. An A-->G substitution was found in the third amphipathic repeat of the E isoform. This substitution causes a Lys-->Glu substitution at amino acid position 76 (Lys76-->Glu), adding two negative charges to the E isoform compared to the I isoform, consistent with their relative mobilities on IEF gels. Restriction isotyping was used to identify the substitution in leukocyte DNA from 15 baboons that had been typed by IEF, thus verifying Lys76-->Glu as the basis for the charge differences between the I and E isoforms. Physiological effects of the Lys76-->Glu substitution on high density lipoprotein-C levels were investigated in 431 baboons carrying the E and I isoforms. These studies revealed that the I isoform was associated with higher levels of high density lipoprotein-C on a high cholesterol, saturated fat diet (p = 0.04). The cDNA sequences showed that the carboxyl terminus of baboon apoA-IV contains a region of hydrophilic repeats (Glu-Gln-X-Gln) that is the largest yet found in any species (nine repeats compared to three to five repeats in human, mouse, and rat). A common length polymorphism was identified that inserts a single amino acid to form a five amino acid repeat. This is the first report of this type of length variation (insertion of a single amino acid rather than insertion of an entire repeat) in this region. In addition, a rare variant was found that inserts an entire four-amino-acid repeat, similar to the human apoA-IV-0 isoform.

We tested the hypothesis that breast and formula feeding differentially affect hepatic mRNA concentrations for LDL receptor (LDL-R) and apolipoproteins A-I, B and E in infant baboons during the preweaning period. The mRNA concentrations were measured in liver biopsies obtained prior to weaning at 14 weeks from 43 baboons that were either breast-fed (n = 17) or fed formulas with a high (n = 12) or low (n = 14) polyunsaturated/saturated (P:S) fat ratio. Breast-fed baboons had 99% higher LDL-R mRNA concentrations compared with infants fed formulas, but there were no differences among breast and formula-fed baboons in mRNA concentrations of apolipoproteins A-I, B or E. The fatty acid P:S ratio of the formulas did not affect hepatic LDL-R or apolipoprotein mRNA concentrations. These results suggest that breast-feeding increases LDL-R gene expression even though breast milk is higher in cholesterol and saturated fat compared with formulas.

We characterized the preweaning differences in cholesterol metabolism between breast-fed and formula-fed baboons and determined if formulas with low and high polyunsaturated:saturated fatty acid (P:S) ratios simulated the effects of breast feeding. At birth, 45 infant baboons from three sires and 44 dams were assigned to breast-fed, low P:S formula or high P:S formula diet groups until weaning at 14 wk. From 4 to 14 wk breast-fed infants had higher serum cholesterol because of much higher HDL1- and HDL2-cholesterol concentrations but had lower HDL3-cholesterol than both formula-fed groups. LDL-cholesterol was higher in infants fed the low P:S fomula. Breast-fed infants had higher serum apolipoprotein E than the formula-fed groups, but diet did not affect apolipoprotein A-I or B concentrations. Breast-fed infants had higher hepatic acyl CoA cholesterol acyltransferase activity and lower plasma lecithin cholesterol acyltransferase activity. These enzyme activities were not different between infants fed low or high P:S formulas. Post-heparinized plasma lipoprotein lipase activity was greater in breast-fed infants than in those fed formula. These findings demonstrate that the P:S ratio of formulas has little effect on cholesterol metabolism during the preweaning period and suggest that factors other than fat composition account for the metabolic differences between breast feeding and commercial infant formula.

We investigated the effects of a polymorphic PvuII site in the gene for lecithin:cholesterol acyltransferase (LCAT) on serum high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) concentrations in a population of 750 pedigreed baboons. We also tested for genotype by diet interactions using data on HDL-C and apo A-I concentrations on two diets (chow and high-cholesterol, saturated fat). A significant (P < 0.001) association between the LCAT genotypes and HDL-C levels was observed. On both diets, animals homozygous for the less common allele had HDL-C levels that averaged 18-19% lower than animals homozygous for the more common allele. HDL-C levels of the heterozygotes were intermediate. The LCAT RFLP accounted for approximately 5% of the variation in HDL-C levels on the two diets. We observed no strong evidence for an LCAT genotype by diet interaction effect.

We tested the hypothesis that plasma thyroid hormone levels in infant baboons are differentially affected by breast-feeding and nursery rearing. Infant baboons were breast-fed (n = 17), or fed formulas with a high polyunsaturated to saturated fat ratio (P/S) (n = 13), or a low P/S formula (n = 14). Plasma total triiodothyronine (T3) and free T3 (fT3) concentrations increased from 4 to 14 weeks of age in infants fed either formula, but decreased in breast-fed infants. At 9 and 14 weeks of age, infants fed the formulas averaged 31% higher T3 and 53% higher fT3 concentrations compared with breast-fed infants. Although T3 concentrations of the high P/S formula group compared with the low P/S formula group were not different at any single age, from 4 to 14 weeks the T3 averaged 19% higher in the high P/S formula group. Plasma total thyroxine (T4) or free T4 (fT4) concentrations were not significantly different among the diet groups during the preweaning period. In summary, formula-fed infants maintained higher plasma T3 and fT3 levels compared with breast-fed infants in the late preweaning period.

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.

A polymorphic Pvu II site was mapped to intron 5 of LCAT, the gene encoding baboon lecithin: cholesterol acyltransferase (LCAT). In a study of 83 baboons, heterozygous baboons (Pv1/Pv2) had significantly higher LCAT enzyme activity levels than did baboons homozygous for the more common allele (Pv1/Pv1). LCAT genotype explained 6% of the total variation in LCAT enzyme activity. To test for allelic effects on cholesterol metabolism, we compared serum concentrations of high density lipoprotein (HDL) cholesterol and apolipoprotein A-I (apo A-I). We also compared distributions of cholesterol and apo A-I among three HDL size classes (HDL1, HDL2, and HDL3). All measurements were obtained for each baboon after long-term feeding of a basal diet low in cholesterol and fat and again after 7 weeks on an atherogenic diet. Heterozygous baboons had significantly lower serum levels of total cholesterol than did homozygotes. In addition, we detected significant effects of LCAT genotype on size distributions of HDL cholesterol and apo A-I on both diets but did not detect any genotype-by-diet interaction. Heterozygotes had increased amounts of cholesterol and apo A-I in HDL3 particles and lower amounts of cholesterol and apo A-I in the larger HDL size classes by comparison with homozygotes. Overall, the LCAT polymorphism explained a significant proportion of total variation in cholesterol (4-10%) and apo A-I (13%) distributions on both diets. Thus, the results indicate that the LCAT polymorphism is associated with significant differences in LCAT enzyme activity and with alterations in HDL compositions.

We previously reported that female baboons overfed during infancy were not fatter at weaning, but developed hypertrophic obesity after puberty. To clarify the mechanisms of this dietary effect on adipocyte hypertrophy, we determined the effects of infant overfeeding on preweaning plasma hormone and triglyceride levels and their relationship with fat cell volume at weaning (19 weeks of age). Newborn female baboons from 3 sires and 24 dams were fed either 280 kilojoules (normally fed; n = 12) or 395 kilojoules (overfed; n = 10) per 100 g Similac formula for 18 weeks. Both formulas contained 9.2%, 43.1%, and 48.5% of calories as protein, carbohydrate, and fat, respectively. During the first 9 weeks, overfed infants had significantly higher fasting and postprandial insulin, total T3, and free T3 concentrations; lower cortisol levels; and lower excretion of urinary 17-hydroxycorticosteroids (17-OHCS) than normally fed infants. These effects were no longer significant at 17-18 weeks. Infant diet did not influence fasting and postprandial plasma triglyceride levels, and fat cell volume was not influenced by energy intake. However, fat cell volume was positively associated with postprandial triglyceride concentrations and inversely associated with postmeal nadir cortisol levels. These results demonstrate that infant overfeeding initiates early alterations in insulin, T3, free T3, and cortisol, but these effects persist only as long as there is a significant increase in energy intake.

Sexual dimorphism is evident in many quantitative genetic traits, and there has been much speculation on the evolution of primate sexual dimorphism. Morphological characters have been the main focus of attention, while sexual dimorphism in physiological quantitative traits has been neglected. In either case, the genetic basis of primate sexual dimorphism has received little attention. This study characterizes genotype by sex (GxS) interactions in two physiological traits, serum apolipoprotein AI (apo AI) and high density lipoprotein cholesterol (HDL-C) concentrations, in baboons fed two different diets, a basal diet and a high cholesterol saturated fat (HCSF) diet. A GxS interaction effect on a trait indicates a heritable component of male/female differences in that trait. Using maximum likelihood methods, eight different quantitative genetic models were evaluated. Significant GxS interactions were found for serum apo AI and HDL-C concentrations on the basal diet. GxS interactions were suggested for serum apo AI and HDL-C concentrations on the HCSF diet, but they were not statistically significant. These results reveal that sexual dimorphisms in serum apo AI and HDL-C concentrations in baboons are heritable, with heritabilities that are influenced by diet. © 1992 Wiley-Liss, Inc., (Copyright © 1992 Wiley‐Liss, Inc., A Wiley Company.)

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.

Mixed model complex segregation analyses have in the past ignored the possibility of genotype-covariate interaction. Only in the nonmixed model with polygenic heritability equal to zero have segregation analyses been performed that allowed for genotype specific regression of the phenotype on covariates. We present an extension of Hasstedt's [1982] mixed model likelihood approximation which does allow for genotype-covariate interaction in the mixed model. Following description of this approximation, we validate the likelihood calculation by a Monte Carlo procedure based on the actual pedigree and missing data structure used in a complex segregation analysis of low density plus very low density lipoprotein cholesterol (LDL-C + VLDL-C) in baboons. The observed averages of the bootstrap parameter estimates adequately recover the generating values, which included parameters specifying genotype-covariate interaction. We then applied both a traditional complex segregation analysis and an analysis with genotype-covariate interaction to test for the presence of a major locus affecting LDL-C levels in baboons. The model including genotype-covariate interaction was significantly different from the model without interactions, and strongly supported the hypothesis that there is a segregating Mendelian locus as opposed to a random environmental factor. This major locus accounts for approximately 46% of the variance in LDL-C levels, as compared to 40% explained by a locus with no genotype-covariate interaction.

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)

Although of great clinical and biological importance, the role of genotype-diet interaction in lipoprotein metabolism and atherosclerosis is still poorly understood. We analyzed serum apolipoprotein A-I (apo A-I) concentrations of approximately 600 pedigreed baboons that were fed two dietary regimens: (1) a basal diet and (2) an atherogenic (high-cholesterol, saturated-fat) diet. Complex segregation analysis was performed separately for apo A-I concentrations in each dietary environment. A major locus model with a recessive allele for high levels of apo A-I and a polygenic component best fit the family data for both diets. Using bivariate segregation analysis, we showed that the major genes detected in the univariate analyses represent two distinct loci that act additively to determine apo A-I concentrations. These two loci accounted for approximately 40% of the total phenotypic variance in apo A-I levels in each dietary environment and were also responsible for 33% of the variation in apo A-I response to the atherogenic diet. Both major loci were influenced by genotype-diet interaction in which the two-locus genotypes exhibited heterogeneous responses to the atherogenic diet. Most genotypes responded to the atherogenic diet with an increase in apo A-I, but two genotypes showed a decrease that can be traced to the effect of one of the major loci. The presence of two major loci and genotype-diet interaction may be responsible for the equivocal results obtained in human pedigree studies of apo A-I.

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.

The effects of 2 different dietary fats (40% of calories from corn oil or coconut oil), in the presence of high-dietary cholesterol (1.7 mg/kcal), on the lipoprotein profiles of baboons (Papio cynocephalus sp) were studied by analytic ultracentrifugation, gradient gel electrophoresis (GGE), and heparin-manganese chloride precipitation. Relative to the corn oil (polyunsaturated fat) diet, the coconut oil (saturated fat) diet significantly increased total serum cholesterol by 43% (P less than 0.001) by increasing non-precipitable cholesterol (HDL-C) 58% (P less than 0.001) and precipitable cholesterol (VLDL + LDL-C) 35% (P less than 0.001). Analytic ultracentrifugal observations indicated that the increase in HDL-C was due to considerable increases in both HDL-I (baboon HDL of size 100-125 A and hydrated density 1.063-1.120 g/ml) and F1.20 degrees 9-28 lipoproteins (material of size 125-220 A and hydrated density 1.03-1.08 g/ml, and containing HDL apolipoproteins and apo E). Concentrations of other HDL subpopulations were unaffected by the dietary saturated rat. The increase in VLDL + LDL-C was due to increased LDL (S degree F 5-12 lipoproteins) and, to some extent, F1.20 degrees 9-28 lipoproteins because the larger, faster floating subspecies of the F1.20 degrees 9-28 lipoproteins were precipitable by heparin-manganese. In contrast, saturated fat (relative to polyunsaturated fat) induced lower concentrations of IDL (SF degree 12-20) and VLDL (SF degree 20-100). Lipoprotein size distributions by GGE indicated 5 HDL subpopulations and 2 or more LDL subpopulations in the sera of most baboons. The type of dietary fat did not affect the particle size range of each of the the HDL or LDL subpopulations. The results indicate that dietary fat markedly modulates the distribution of cholesterol between apo A-I-containing (HDL and F1.20 degrees 9-28) and apo B-containing (IDL and VLDL) lipoproteins without altering the presence of subpopulations based on particle size.

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.

We examined the relationship of hypertension and plasma renin activity to atherogenesis in 48 moderately hyperlipidemic (total serum cholesterol was about 200 mg/dl) baboons (Papio sp.). We used renal artery stenosis (two-kidney, one clip model) to produce hypertension associated with elevated plasma renin activity, and used cellophane wrapping of both kidneys (bilateral perinephritis model) to produce hypertension with normal renin activity. Renal artery stenosis and bilateral perinephritis increased both systolic and diastolic blood pressure by about 30 mm Hg. Renal artery stenosis approximately doubled, but bilateral perinephritis did not change plasma renin activity. Both hypertensive groups, to about the same degree, had significantly more extensive atherosclerosis than the control group in the abdominal aorta and brachial, iliac-femoral, and carotid arteries. The effect of hypertension was greatest in the carotid arteries where the extent of atherosclerosis was nearly tripled. Hypertension did not influence lesions in the thoracic aorta. By multiple regression analysis, very low plus low density lipoprotein cholesterol, high density lipoprotein cholesterol, and systolic blood pressure were consistently strong predictive variables for the extent of atherosclerotic lesions. Most of the effects of renal hypertension on atherosclerotic lesions appeared to be accounted for by the increase in blood pressure. In the carotid arteries, however, there was a suggestion of an effect above that due to increased blood pressure. Additional analyses indicated that these treatment effects were associated with serum potassium concentration, plasma renin activity, or other closely related variables.

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.

Fast atom bombardment mass spectrometry was used to identify molecular species of platelet-activating factor (PAF) produced by stimulated human neutrophilic polymorphonuclear leukocytes. Normal and reverse-phase high performance liquid chromatography were employed to separate the individual regions with PAF activity prior to mass spectrometric analysis. The following alkyl chain homologs of acetyl glyceryl ether phosphorylcholine (AGEPC) were found: C16:0, C17:0, C18:0 and C18:1. There was also evidence for the presence of the C15:0 homolog, as well as other species which have not yet been identified.

Atherosclerosis and coronary heart disease are promoted by elevated serum low density lipoprotein cholesterol (LDL-C) and are retarded by increased high density lipoprotein cholesterol (HDL-C). Considerable variability in these lipoproteins has been observed in studies of captive animals subjected to extensive experimental manipulations, or by epidemiological studies of human beings. We have examined these variables in wild male baboons living undisturbed in their natural habitat in the Serengeti Ecosystem of East Africa. Among socially subordinate males, HDL-C and apolipoprotein A-I concentrations were significantly reduced by 31% and 25%, respectively, compared to concentrations in dominant individuals. There were no social rank differences in VLDL + LDL-C or its apolipoprotein (Apo B). Differences in age, sex hormone concentrations, rank-related diet, body weight, or gene pools were unlikely to explain this rank-related pattern. However, diminished HDL-C concentrations were associated with elevated basal cortisol concentrations, suggesting that exposure of subordinate individuals to elevated levels of social stressors could cause lower HDL-C concentrations.

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.

Silica and C18 reverse phase high performance liquid chromatography (HPLC) were used to fractionate synthetic molecular species of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) and semi-synthetic platelet-activating factor (PAF) synthesized from beef heart plasmalogens. A single coincident peak from silica HPLC was observed for either a mixture of synthetic AGEPC's with alkyl chain lengths from C12 to C18 or for beef heart-derived PAF. This peak was well separated from other classes of phospholipid standards including 2-lysophosphatidylcholine and 3H-labeled lyso-PAF. Subsequently, the synthetic AGEPC mixture or beef heart PAF was separated into individual species on a C18 reverse phase column. Beef heart-derived PAF was fractionated into at least four molecular species of PAF activity which had similar retention times as the radioactivity of 3H-labeled beef heart PAF. Approximately 56% of the radioactivity of 3H-labeled PAF was found in the fraction with a similar retention time as 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine, 10% as 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine, 11% as 1-O-pentadecyl-2-acetyl-sn-glycero-3-phosphocholine, and 13% in an unidentified fraction which eluted after C-16-AGEPC. The unidentified fraction did not correspond to any of the homologous series of synthetic AGEPCs with saturated alkyl chain lengths from C12 to C18. Recoveries of radioactive phospholipids from silica or reverse phase columns were greater than 95%.

Statistical methods for detecting the contribution of major genes to quantitative phenotypes have been widely applied in human family studies. Some of these methods are reviewed, and their application to analysis of an animal model for a human disease is described. Analysis of lipoprotein concentrations in pedigreed baboons provides evidence for genetic effects on specific lipoprotein components that have been associated with reduced susceptibility to atherosclerosis in humans.

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.

In separate experiments, we fed 30 male and 25 female baboons a diet enriched in cholesterol and saturated fat for periods of 3.3 and 2.6 years. Using operant conditioning with water rewards, we trained the animals to puff on smoking machines in a human-like manner. Half of the animals smoked more than 40 cigarettes per day, while the remaining animals (controls) puffed air. Initially, the diet produced twofold (males) and threefold (females) elevations from baseline levels in serum cholesterol concentrations, but over the course of the experiments, the serum cholesterol decreased to 1.5 (males) and 2.0 (females) times baseline levels in both cigarette smokers and controls. Blood carbon monoxide concentration, plasma thiocyanate concentration, and urine cotinine concentration were significantly greater in smokers than in controls. Responses to smoking in males included lymphocytosis, elevated fasting blood glucose concentration, and decreased seminal vesicle weight. In females, hemoglobin and mean corpuscular hemoglobin concentrations were elevated. The extent of atherosclerosis was examined after 2.8 (males) and 1.6 (females) years of smoking. Among males, the extent of lesions in carotid arteries was significantly greater in smokers than in controls, but there were no significant differences in atherosclerosis in the aorta or the brachial, iliac-femoral, or coronary arteries. Among females, there were no significant differences in atherosclerosis between smokers and controls in any artery. These experiments show little effect of 2 to 3 years of cigarette smoke inhalation and concurrent modest elevation of blood carboxyhemoglobin on experimental atherosclerosis in the presence of moderate hyperlipidemia.

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.

Some progeny of baboons (Papio sp.) selectively bred for a high response of serum cholesterol to an atherogenic diet have high serum levels of unusual lipoproteins with flotation rates of F degrees 1.20 9-28, intermediate between those of low and high density lipoproteins (HDL). They are similar to the fraction of HDL commonly called HDL1. We conducted a cross-over experiment to determine the roles of dietary cholesterol and saturated fat in eliciting these lipoproteins in the progeny of two affected sires. Half of the progeny of each sire manifested the trait (high HDL1 phenotype) while consuming an atherogenic diet and half did not (low HDL1 phenotype). While consuming a chow diet, high HDL1 progeny had higher total serum cholesterol concentrations than did low HDL1 progeny. This difference was exaggerated when the animals consumed diets enriched in either cholesterol or saturated fat (lard), and was greatest when the diet contained both. High HDL1 animals also had considerably higher serum apo E concentrations, and slightly higher serum apo A-I concentrations. High HDL1 progeny had much higher levels of cholesterol (twofold) and of apo A-I (three- to eightfold) in HDL1 fractions than did low HDL1 progeny. There were significant interactions between HDL1 class and both dietary cholesterol and saturated fat in their effects on other lipoprotein fractions. High HDL1 animals had an exaggerated elevation of cholesterol and apo B in very low, intermediate, and low density lipoproteins in response to dietary cholesterol. They also had an exaggerated elevation of cholesterol in the lighter HDL1 fraction (d = 1.041-1.053), and lesser elevation of cholesterol and apo A-I in HDL2.