ApoE and apoC-III-defined HDL subtypes: a descriptive study of their lecithin cholesterol acyl transferase and cholesteryl ester transfer protein content and activity.

BACKGROUND: The functionality of high-density lipoproteins (HDL) is a better cardiovascular risk predictor than HDL concentrations. One of the key elements of HDL functionality is its apolipoprotein composition. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are enzymes involved in HDL-mediated reverse cholesterol transport. This study assessed the concentration and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans. METHODS: Eighteen adults (ten women and eight men, mean age 55.6, BMI 26.9 Kg/m2, HbA1c 5.4%) were studied. HDL from each participant were isolated and divided into four subspecies containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E + C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E + C+). The concentration and enzymatic activity of LCAT and CETP were measured within each HDL subspecies using immunoenzymatic and fluorometric methods. Additionally, the size distribution of HDL in each apolipoprotein-defined fraction was determined using non-denaturing electrophoresis and anti-apoA-I western blotting. RESULTS: HDL without apoE or apoC-III was the predominant HDL subtype. The size distribution of HDL was very similar in all the four apolipoprotein-defined subtypes. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6% of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8, 12.2 and 8.37% of plasma LCAT respectively for E + C-, E-C+ and E + C+). LCAT mass was lower in E + C- HDL relative to E-C- HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and concentrations of both E-C+ pre-beta HDL (r = - 0.55, P = 0.017) and E-C- alpha 1 HDL (r = - 0.49, P = 0.041). Conversely, there was a direct correlation between plasma CETP activity and concentrations of E-C+ alpha 1 HDL (r = 0.52, P = 0.025). CONCLUSIONS: The presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol. These results favor an interpretation that LCAT and apoE interact to enhance anti-atherogenic pathways of HDL.

Time Course of Decrease in Skeletal Muscle Mitochondrial Biogenesis after Discontinuation of High-Fat Diet.

It is known that a high-fat diet induces an increase in mitochondrial biogenesis in skeletal muscle. To examine the time course of decrease in mitochondrial biogenesis in skeletal muscle after discontinuing a high-fat diet feeding, C57BL/6 mice were fed a high-fat diet for 4 wk and then switched to the control diet for another 3 or 7 d. During the high-fat diet withdrawal period, the protein content of the mitochondrial respiratory chain decreased faster than the fatty acid oxidation enzymes. The mitochondrial DNA copy number remained high for at least 1 wk after withdrawing the high-fat diet. These results suggested that after switching to the control diet following a period of high-fat diet, the increased mitochondrial biogenesis levels are maintained for a few days, and the rate of decline is divergent between the different mitochondrial components.

Lipoproteins containing apolipoprotein A-IV: composition and relation to cholesterol esterification.

In order to investigate the relationship of lipid and apolipoprotein composition to cholesterol esterification in lipoproteins containing apolipoprotein (apo) A-IV, apo A-containing lipoprotein particles were isolated from fresh human plasma using a system of sequential immunoaffinity chromatography. Plasma was first depleted of apo B- and apo E-containing lipoproteins. Four major subpopulations of apo A-containing lipoprotein particles were separated: Lp A-I, Lp A-I: A-II, Lp A-IV and Lp A-I: A-IV: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained less total lipid, less cholesterol and more triacylglycerol than Lp A-I and Lp A-I: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained more sphingomyelin and less phosphatidylcholine than Lp A-I and Lp A-I: A-II and were richer in (16:0 + 18:0) saturated fatty acids. Among these isolated lipoprotein particles, Lp A-IV contained the highest lecithin: cholesterol acyltransferase (LCAT) activity per micrograms of protein. Cholesterol esterification rates were 2.6 +/- 0.5, 5.3 +/- 0.4 and 0.8 +/- 0.2 mumol of cholesterol per hour per mg of lipoproteins for Lp A-IV, Lp A-I and Lp A-I: A-II, respectively. The apolipoprotein and lipid composition and LCAT activity of Lp A-IV suggest that this lipoprotein may be a source of cholesterol esterification in plasma.

Follicular fluid lipoproteins in the mare: evaluation of HDL transfer from plasma to follicular fluid.

Using a density gradient ultracentrifugal procedure, we have separated equine plasma and follicular fluid high-density lipoproteins (HDL). The density distribution of the follicular fluid HDL was clearly displaced towards the highest densities in comparison with that of plasma HDL. Similarly, an analysis of size distributions showed a decrease in follicular fluid HDL diameters (4.2 to 9.2 nm) compared to plasma HDL (5.5 to 9.5 nm). HDL were isolated into three subfractions on the basis of the disposition of the Sudan Black stained bands in the centrifuge tubes. Concentrations of each subfraction were clearly lower in the follicular fluid, and the relative percentages with regard to the plasma equivalents were inversely proportional to the molecular weights (23.8% for HDL-1, 49.9% for HDL-2 and 63.7% for HDL-3). The cholesterol/phospholipid molar ratio and the esterified/free cholesterol molar ratio were clearly increased in the follicular HDL-2 and HDL-3 subfractions. The apolipoprotein distribution in follicular fluid HDL was very close to that in plasma HDL. LCAT activity measured in human as well as equine samples was weaker in follicular fluid compared to plasma in both species (4.0 nmol of free cholesterol esterified per h per ml vs. 24 nmol per h per ml). Theoretical concentrations of follicular fluid HDL were calculated assuming that the HDL particles would be merely a filtration product undergoing no detectable metabolic modifications. Biochemical measurements showed that the lightest particles (HDL-1) were less numerous than suggested by the theoretical calculation. Thus, although follicular fluid HDL appear to be a filtration product of plasma HDL, they undergo metabolic transformations that we suggest may be linked to hormonal synthesis and reverse cholesterol transport.

Tangier disease: isolation and characterization of LpA-I, LpA-II, LpA-I: A-II and LpA-IV particles from plasma.

Tangier disease (TD) is characterized by extremely low plasma levels of HDL, apoA-I and apoA-II due to very rapid catabolism. However, the risk of premature coronary heart disease (CHD) is not markedly increased in TD. In order to gain insight into reverse cholesterol transport in TD, we isolated LpA-I, LpA-I:A-II, LpA-II and LpA-IV particles from fasting plasma of 5 TD patients. LpA-I composition was similar to control LpA-I, but TD LpA-I had more LCAT and CETP activity (respectively, 0.35 +/- 0.14 and 0.14 +/- 0.04 mumol of cholesterol esterified/h/micrograms of protein, and 7 +/- 2.5 and 1.4 +/- 0.3 mumol of cholesteryl ester transferred/h/micrograms of protein). In contrast, TD LpA-I:A-II had abnormal composition, with a low molar ratio of apoA-I to apoA-II (0.2-1.33). In addition, LpA-I:A-II in TD contained a substantial amount of apoA-IV compared with control, making this particle an LpA-I:A-II:A-IV complex. LpA-I:A-II from normal plasma do not promote cholesterol efflux from adipocytes cells, whereas TD LpA-I:A-II:A-IV complexes promoted cholesterol efflux from these cells. Moreover LpA-I:A-II:A-IV complexes have more LCAT and CETP activity than control (respectively 1.2 +/- 0.16 and 0.05 +/- 0.01 mumol of cholesterol esterified/h/micrograms of protein and, 41 +/- 3.7 and 1 +/- 0.4 mumol of cholesteryl ester transferred/h/micrograms of protein). The LpA-II particle in TD represented in fact an LpA-II:A-IV complex (75% mol apoA-II and 22% mol apoA-IV).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of apolipoprotein A-I, lecithin:cholesterol acyltransferase and glucocerebrosidase genes in hypoalphalipoproteinemia.

Hypoalphalipoproteinemia (HALP) is a dyslipidemia characterized by low HDL-cholesterol (HDL-C) levels with important genetic contribution. However, no common genetic mutations have been found to be associated with this disorder. We screened the promoter and coding sequence of apolipoprotein (apo) A-I and lecithin:cholesterol acyltransferase (LCAT) genes and the 5' apo C-III region by SSCP and heteroduplex analysis, and DNA sequencing in 66 unrelated subjects with recurrent low HDL-C levels. We also analyzed the N370S and L444P variants, in the glucocerebrosidase (GBA) gene by restriction fragment analysis. Three mutations in the apo A-I gene (L144R, W108R, g.1833C>T) and 3 mutations in the LCAT gene (S208T, I178T, IVS3-23C>A) were detected, in six heterozygous subjects. In addition, a novel polymorphic site in LCAT gene (g.4886C>T) has been identified. Allelic frequencies of polymorphisms g.(-636)C>A, g.(-625)G>A, g.(-620)T>del, g.(-479C>T and g.(-452)T>C, located upstream of the apo C-III gene, were in normal range, and no other mutation was found in this region. Two HALP subjects were found to carry the N370S mutation at GBA locus. In conclusion, 12% of HALP subjects were found to carry mutations in apo A-I, LCAT, or GBA genes, which could explain this phenotype. Our results confirm the molecular, genetic and phenotypic heterogeneity of HALP.

Heterozygosity for ABCA1 gene mutations: effects on enzymes, apolipoproteins and lipoprotein particle size.

A cohort of 13 female and 14 male heterozygotes for ATP binding cassette A1 (ABCA1) gene defects was directly compared with 13 and 14 unaffected female and male family members of almost exact same age. The activities of three proteins that play key roles in HDL metabolism were measured in addition to extensive lipid and (apo) lipoprotein subfraction analysis. Compared to controls, LCAT activity was reduced by 15% in affected subjects (P < 0.001) while PLTP activity was unaffected. Interestingly, CETP activity was elevated by 50% in the heterozygote siblings of one kindred but was unaffected in heterozygotes of the three other families. With respect to lipids, the heterozygotes had normal total cholesterol (TC), and LDL-cholesterol concentrations but presented with a trend towards increased triglyceride levels (13%; P = 0.08). HDL metabolism, by contrast, was severely affected as illustrated by 40% reductions in HDL-cholesterol (P < 0.001) with concomitant reductions in apoAI (25%; P < 0.001) levels and in lipoprotein subfraction LpAI (28%; P < 0.001), LpAI:AII (24%; P=0.014), and LpCIII:nonB (34%; P < 0.001) concentrations. We furthermore observed reduced average HDL particle size (5%; P = 0.004; 16% in female and 3.6% in male) and reduced plasma apoCIII concentration (15%; P = 0.006) while apoAII, apoAIV, apoE and apoB levels were unchanged. In conclusion, heterozygosity for ABCA1 defects was associated with reduced LCAT activity in absence of effects on PLTP activity. Of special interest was our finding that the effects of compromised ABCA1 function on HDL were more pronounced in women than in men.

Atherosclerosis and lipoprotein metabolism: role of reverse cholesterol transport.

To understand the complexity of lipoprotein metabolism and its influence on atherosclerosis, one must be aware of the physiologic characteristics and functions of the different lipoprotein classes, apolipoproteins and enzymes. Understanding of the dynamics of cholesterol and lipoprotein metabolism, especially reverse cholesterol transport, will aid in finding a means of preventing and reversing the atherosclerotic process.

Improvement of the lipid profile during long-term administration of pindolol and hydrochlorothiazide in patients with hypertension.

The effect of the combined administration of pindolol (10 or 20 mg daily) and hydrochlorothiazide (50 mg daily) on the serum lipid and lipoprotein levels of 34 hypertensive patients was investigated for 6 to 18.5 months (mean 13.3). Placebo control data were compared with the results obtained during treatment periods in each patient by paired t tests. Mean levels of high-density lipoprotein cholesterol increased by 17% (p less than 0.01), low-density lipoprotein cholesterol decreased by 4% (p less than 0.01) and the high-density lipoprotein: low-density lipoprotein cholesterol ratio increased by 28% (p less than 0.01). Total serum cholesterol, serum triglycerides and very low-density lipoprotein cholesterol showed no statistically significant changes from control values. These findings suggest that the long-term administration of this beta blocker combined with a diuretic results in serum lipid changes considered beneficial in the evaluation of risk factors for coronary artery disease.

Isolation and properties of rat plasma lecithin-cholesterol acyltransferase.

Lecithin-cholesterol acyltransferase was purified from rat plasma and the properties of this enzyme during the purification procedures and those of the purified enzyme were investigated in comparison with the human enzyme. The rat enzyme was not adsorbed on hydroxyapatite, which was employed for the purification of the human enzyme. When purified human enzyme was incubated at 37 degrees C in 0.1 mM phosphate buffer (pH 7.4; ionic strength, 0.00025), no alteration of enzyme activity was observed for up to 6 h. In the case of the rat enzyme, however, approximately 40% of the enzyme activity was lost under the same conditions. The human enzyme and rat enzyme were both retained on a Sepharose 4B column to which HDL3 was covalently linked, in 39 mM phosphate buffer, pH 7.4. Although the human enzyme was eluted from the column in 1 mM phosphate buffer, the rat enzyme was dissociated from the column at a lower buffer concentration (0.1 mM phosphate buffer). These findings indicate that the rat enzyme effectively associated with HDL3 in 39 mM phosphate buffer, pH 7.4, but the association was more sensitive to increase of ionic strength compared with that of the human enzyme.

Lipoprotein composition in insulin-dependent diabetes mellitus with chronic renal failure: effect of kidney and pancreas transplantation.

Chronic renal failure (CRF) in nondiabetics is associated with a number of lipoprotein abnormalities that place these patients at high risk for atherosclerosis. This study compared the lipoprotein composition of nondiabetic controls (n = 68) with that of patients with insulin-dependent diabetes mellitus ([IDDM] n = 13) and of patients with IDDM and CRF ([IDDM + CRF] n = 74). Six lipoprotein subfractions (very-low-density lipoprotein [VLDL], intermediate-density lipoprotein [IDL], low-density lipoprotein [LDL], high-density lipoprotein-light [HDL-L], HDL-medium [HDL-M], and HDL-dense [HDL-D]) were isolated by rapid gradient ultracentrifugation using a fixed-angle rotor. The apolipoprotein (by reverse-phase high-performance liquid chromatography [HPLC]) and lipid (by enzymatic assays) composition of each subfraction was determined. The only abnormalities found in IDDM patients were increases in IDL and HDL-L triglyceride (TG) levels and an increase in the HDL-L free cholesterol (FC) level. The IDDM + CRF group had multiple abnormalities including (1) elevated TG, apolipoprotein (apo) C-II, and apo C-III levels in all lipid subfractions; (2) elevated VLDL and IDL apo B, TG, FC, cholesterol ester (CE), and phospholipid (PL) levels (with an increased CE/TG ratio in VLDL only); (3) decreased HDL-M apo A-I, apo A-II, CE, and PL levels, but an increased HDL-D apo A-I level; and (4) decreased lecithin:cholesterol acyltransferase (LCAT) activity. Twenty-five of the IDDM + CRF patients underwent combined pancreas and kidney (P + K) transplantation, and 12 patients received only a kidney transplant. Lipoprotein composition was determined at 3, 6, and 12 months posttransplant. Both types of transplantation resulted in similar alterations in lipoprotein composition, even though there was essential normalization of blood glucose levels in most of the patients who received a pancreas transplant (hemoglobin A1C [HbA1C], 9.1% +/- 1.1% v 5.7% +/- 0.3% at 12 months, P < .01). These posttransplant changes included (1) no improvement in the elevated TG level in any lipid subfraction even though there was some reduction in apo C-III levels in VLDL; (2) reductions in levels of VLDL and IDL apo B but increases in LDL apo B; (3) increases in HDL apo C-III and FC concentrations despite an increase in LCAT activity; and (4) increases in apo A-I levels in HDL-L and HDL-M. The addition of a pancreas to a kidney transplant had no obvious impact on the lipoproteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Lecithin: cholesterol acyl transferase (LCAT).

Esterification of cholesterol in plasma is mediated by LCAT. The mechanism of the three reactions catalysed by the enzyme is beginning to be understood. LCAT has been purified from human plasma and partially characterized. The enzyme is closely associated with HDL and exists most likely as a complex with its activator apo A-I and apo D. Antibodies were raised against LCAT and the enzyme concentration in plasma has been estimated to range between 4.5 and 8.0 mg/L. In patients with familial LCAT deficiency only trace amounts or no LCAT protein is found. Heterozygotes for this disorder have approximately half the normal amount of the enzyme. LCAT reactivity is essential for normal lipoprotein metabolism and for a proper equilibrium between tissue and plasma cholesterol.

The apo E/apo CIII molar ratio affects removal of cholesterol ester from modified human lipoproteins injected into cebus monkeys.

The removal of postprandial (PP) and postabsorptive (PA) human LDL and HDL cholesterol was examined in cebus monkeys (Cebus albifrons) following in vitro labelling of these lipoproteins by 3H-cholesterol in the presence or absence of DTNB. The removal of LDL cholesteryl ester was 3.5 and 2 times greater than that of HDL in male and female monkeys, respectively. Incubation with DTNB reduced cholesteryl ester removal by 45 and 52% for LDL and HDL, respectively. Cholesteryl ester from PA lipoproteins was removed 80% faster than that PP particles only when plasma was incubated without DTNB. Cholesterol removal from these lipoproteins was positively (r = 0.941) and significantly (P less than 0.001) correlated with the molar apo E/apo CIII ratio. The data suggest that density of lipoproteins was less important than their apoprotein composition in dictating their removal from circulation.

Short-term changes in lipid and protein metabolism in liver transplants from living-related donors.

The effects of liver transplantation involving living-related donors were investigated in 20 pediatric cases in terms of protein and lipid metabolism using the extent of cholesterol esterification and the levels of total cholesterol, lecithine-cholesterol acyltransferase, apolipoprotein A-I, cholinesterase, and rapid turnover proteins as parameters. Cholesterol esterification increased from preoperative values of 39% +/- 4% to 67% +/- 1% (mean +/- SEM, n = 17) at 3 weeks after liver transplantation in successful cases but decreased from the preoperative value of 45% +/- 10% to 26% +/- 6% (n = 3) at 3 weeks in unsuccessful cases. Cholinesterase, transferrin, and prealbumin levels remained low after 3 weeks even in successful cases. Patients who had partial liver transplantations from living-related donors showed rapid recovery of cholesterol esterification. However, patients with graft livers required an extensive period before normalization of protein metabolism occurred, indicating the necessity for long-term follow-up of recipient development.

An improvement of Barter's method for assaying plasma cholesterol ester transfer activity: experimental and clinical applications.

The use of a discontinuous density gradient and of a vertical rotor to separate plasma lipoproteins are modifications of Barter's described method for assaying cholesteryl ester transfer activity (CETA) in plasma. The original feature of our approach is the fast preparation of the labeled substrate by a physiologic-like process, which renders the assay easy and suitable for measurement of this activity in both man and animals.

Effect of total parenteral nutrition with intravenous fat on lipids and high density lipoprotein heterogeneity in neonates.

Plasma lipid concentrations and high density lipoprotein (HDL) subclass distributions were evaluated in 22 newborn infants nourished with intravenous (iv)-fat. The majority of infants were premature with respiratory distress syndrome. Based on baseline (prior to iv-fat) HDL subclass profiles determined by gradient gel electrophoresis (GGE), infants fell into two classes, one with two or more pronounced peaks within the normal HDL spectrum (group I, 17 subjects) and the other with highly unusual HDL distribution (group II, five subjects). Total plasma cholesterol increased in both groups during low and high fat intravenous feeding. HDL-cholesterol, however, did not change with iv-fat where mean values for groups I and II at baseline, iv-low fat and -high fat were: group I, 31.2 +/- 7.1, 30.0 +/- 8.8, and 36.6 +/- 16.7 mg/dl, respectively; and group II, 20.0 +/- 7.8, 20.2 +/- 7.4, and 19.8 +/- 8.8 mg/dl, respectively. Unlike HDL-cholesterol levels that remained constant with iv-fat, apolipoprotein (apo) AI concentrations increased significantly: group I, 73.0 +/- 11.0, 88.3 +/- 15.9, and 93.1 +/- 21.9 mg/dl, respectively; and group II, 31.8 +/- 10.5, 41.0 +/- 12.8, and 59.3 +/- 18.5 mg/dl, respectively. In group I infants, iv-fat is associated with an increase in larger-sized particles, particularly in the (HDL2b)gge range; in group II there is an increase in (HDL3b)gge and (HDL3c)gge components and a disappearance of particles that fall outside of the size range of normal HDL. In both groups, enteral feeding is associated with a further normalization of HDL subclass distribution. The aberrant GGE profiles and very low apoAI levels of group II infants at baseline were associated with unusual HDL morphology determined by electron microscopy where discoidal structures were prominent. With iv-fat, discoidal particles decline in number while normal spherical structures increase. Prevalence of discoidal HDL at baseline was associated with low concentrations of lecithin:cholesterol acyltransferase (LCAT) (1.12 +/- 0.5 micrograms/ml); with iv-fat this enzyme rose to 1.61 +/- 0.18 micrograms/ml. Increased LCAT is associated with the normalization of HDL morphology. It is likely that iv-fat improves the nutritional status of premature infants, thereby stimulating increased liver synthesis of important proteins, including apoAI and LCAT, associated with HDL metabolism.

Lecithin cholesterol acyltransferase and possible origin of lysolecithin in rabbit aqueous after a damage of blood-aqueous barrier.

Rabbit eye aqueous humor contains lysolecithin (LPC); the LPC concentration markedly increases, if the integrity of the hemato-aqueous barrier is impaired. It is assumed that LPC plays a causal role in the development of cataract because of its detergent action. We have studied the mechanism of LPC cumulation in the aqueous after a mechanical, endotoxic or immunological damage to the hemato-aqueous barrier. We measured in aqueous samples the activity of lecithin cholesterol acyltransferase (LCAT, EC 2.3.1.43), an enzyme which produces LPC and cholesteryl esters in the plasma. The transfer of phospholipids from the plasma into the aqueous was examined in vivo in 32p-prelabeled rabbits. Whereas LCAT was absent in the aqueous humor of intact eyes, an increased transesterification activity could be detected in all cases of impaired hemato-aqueous barrier. The proportion of LPC in aqueous phospholipids was similar to that found in high density lipoproteins, whereas whole plasma and low density lipoproteins contained a much lower proportion of LPC. An increased plasma level of LPC induced by the treatment of rabbits with phospholipase A2 in vivo, did not by itself lead to a preferential passage of plasma LPC through the blood-aqueous barrier. The experimental results rather imply that an impaired blood-aqueous barrier permitted an enhanced transfer from the plasma of intact HDL carrying also LPC and LCAT, and that the enzyme subsequently produced increased amounts of LPC in situ.

Plasma and lipoprotein fatty acid composition in glycogen storage disease type I.

Nocturnal intragastric feeding has been shown to be an effective means to improve clinical and biochemical features in glycogen storage disease type I (GSD-I). In this study, we investigated the fatty acid patterns in a whole plasma and in circulating lipoproteins in patients on this therapy. The results demonstrated massive concentration of total fatty acids coupled with higher levels of triglycerides, free cholesterol, cholesterol ester and phospholipids. This hyperlipidemia involved all fatty acids without distinction of carbon or bond numbers. However, the increase was more pronounced for saturated than polyunsaturated fatty acids, as was demonstrated by the ratios of both oleic acid to linoleic acid (1.91 +/- 0.40 vs 0.80 +/- 0.09 in controls) and of omega 3 + omega 6 to omega 9 fatty acid families (0.92 +/- 0.11 vs 1.66 +/- 0.08 in controls). The fatty acid patterns in very low (VLDL), low (LDL) and high (HDL) density lipoprotein showed substantial differences in composition, reflecting an association between an abnormal lipoprotein pattern and essential fatty acid deficiency. Furthermore, GSD-I patients exhibited a significant increase in VLDL (17 +/- 2 vs 47 +/- 7 mg/dl) and LDL cholesterol (124 +/- 7 vs 206 +/- 24 mg/dl), coupled with a decrease in HDL cholesterol (49 +/- 4 vs 28 +/- 3 mg/dl). These data documenting high LDL cholesterol and low HDL cholesterol associated with an increased concentration and proportion of saturated fatty acids suggest that GSD-I patients on nocturnal intragastric feeding are at high risk for atherosclerosis and its complications.

Dietary safflower phospholipid reduces liver lipids in laying hens.

This experiment was conducted to determine the effects of dietary safflower phospholipids (crude safflower phospholipid and purified safflower phospholipid) on performance and lipid metabolism of laying hens. Sixty-week-old Single Comb White Leghorn laying hens were divided into four groups of seven birds each, and were given one of four experimental diets containing 5% beef tallow (served as a control, tallow), a mixture of safflower oil and palm oil (SP-oil), crude safflower phospholipid (Saf-PLcrude), or purified safflower phospholipid (Saf-PL) for 7 wk. Egg production ratio and daily egg mass were significantly higher in hens fed Saf-PLcrude diets than in hens of the other diet groups. There were no significant differences in egg weight among groups. Liver cholesterol and triglyceride contents were significantly decreased in all treated groups as compared with the control. The activity of hepatic 3-hydroxy-3 methylglutaryl coenzyme A reductase was the highest in hens fed the Saf-PLcrude diet. Serum esterified cholesterol concentration was decreased by feeding of SP-oil, Saf-PLcrude, or Saf-PL diets. Serum lecithin-cholesterol acyltransferase activity was highest in hens fed the tallow diet. Excreta neutral steroid excretion was significantly increased in the Saf-PLcrude or Saf-PL diet groups, although acidic steroid excretion was not affected by dietary treatments. Total cholesterol, triglyceride, and phospholipid contents in egg yolks were not different for any dietary treatments. The fatty acid compositions of egg yolks from hens fed Saf-PLcrude diets were not different with those fed the SP-oil diet, although eggs of hens fed the Saf-PL diet showed lower total polyunsaturated fatty acids. These results suggest that dietary safflower phospholipids may be a valuable ingredient to layers for reducing liver triglycerides and serum cholesterol without any adverse effects.

A rapid method for lecithin:cholesterol acyltransferase estimation in human serum.

All the described procedures for lecithin:cholesterol acyltransferase (LCAT) determination in the plasma have raised criticisms: Lack of sensitivity for methods using colorimetric determination of unesterified cholesterol or phosphatidyl-choline in plasma before and after incubation at 37 degrees C. Incomplete isotopic equilibrium of the free cholesterol substrate between the different lipoproteins in radioassay procedures. Gas-liquid chromatography methods cannot be used when LCAT activity is low. A new method, easier, more sensitive and accurate has been developed in our laboratory:plasma samples are delipoproteinized by coprecipitation with Intralipid, dextran sulphate, and calcium chloride. Cholesterol esterification is assayed by a short incubation (30 min) of 100 microliter delipoproteinized plasma and a 30 microliter of 3H-cholesterol-labelled substrate. About 15% of cholesterol is esterified in these conditions in 30 min (35 +/- 7 micromole/h/l). The LCAT reaction is linear for about one hour.