In Situ Simulation-based Team Training for Post-cardiac Surgical Emergency Chest Reopen in the Intensive Care Unit

Emergency chest reopen of the post cardiac surgical patient in the intensive care unit is a high-stakes but infrequent procedure which requires a high-level team response and a unique skill set. We evaluated the impact on knowledge and confidence of team-based chest reopen training using a patient simulator compared with standard video-based training. We evaluated 49 medical and nursing participants before and after training using a multiple choice questions test and a questionnaire of self-reported confidence in performing or assisting with emergency reopen.

Both video- and simulation-based training significantly improved results in objective and subjective domains. Although the post-test scores did not differ between the groups for either the objective (P=0.28) or the subjective measures (P=0.92), the simulation-based training produced a numerically larger improvement in both domains. In a multiple choice question out of 10, participants improved by a mean of 1.9 marks with manikin-based training compared to 0.9 with video training (P=0.03). On a questionnaire out of 20 assessing subjective levels of confidence, scores improved by 3.9 with manikin training compared to 1.2 with video training (P=0.002).

Simulation-based training appeared to be at least as effective as video-based training in improving both knowledge and confidence in post cardiac surgical emergency resternotomy.

Moderate acute intake of de-alcoholized red wine, but not alcohol, is protective against radiation-induced DNA damage ex vivo -- results of a comparative in vivo intervention study in younger men

Moderate intake of wine is associated with reduced risk of cardiovascular disease and possibly cancer however it remains unclear whether the potential health benefits of wine intake are due to alcohol or the non-alcoholic fraction of wine. We therefore tested the hypothesis that the non-alcoholic fraction of wine protects against genome damage induced by oxidative stress in a crossover intervention study involving six young adult males aged 21-26 years. The participants adhered to a low plant phenolic compound diet for 48 h prior to consuming 300 mL of complete red wine, de-alcoholized red wine or ethanol on separate occasions 1 week apart. Blood samples were collected 0.5, 1.0 and 2.0 h after beverage consumption. Baseline and radiation-induced genome damage was measured using the cytokinesis-block micronucleus assay and total plasma catechin concentration was measured. Consumption of de-alcoholized red wine significantly decreased the gamma radiation-induced DNA damage at 1 and 2 h post-consumption by 20%. In contrast alcohol tended to increase radiation-induced genome damage and complete wine protected against radiation-induced genome damage relative to alcohol. The observed effects were only weakly correlated with the concentration of total plasma catechin (R=-0.23). These preliminary data suggest that only the non-alcoholic fraction of red wine protects DNA from oxidative damage but this effect cannot be explained solely by plasma catechin.

Cholesterol-lowering effects of plant sterol esters and non-esterified stanols in margarine, butter and low-fat foods

OBJECTIVES

To determine the efficacy on plasma cholesterol-lowering of plant sterol esters or non-esterified stanols eaten within low-fat foods as well as margarine.

DESIGN

Randomised, controlled, single-blind study with sterol esters and non-esterified plant stanols provided in breakfast cereal, bread and spreads. Study 1 comprised 12 weeks during which sterol esters (2.4 g) and stanol (2.4 g)-containing foods were eaten during 4 week test periods of cross-over design following a 4 week control food period. In Study 2, in a random order cross-over design, a 50% dairy fat spread with or without 2.4 g sterol esters daily was tested.

SUBJECTS

Hypercholesterolaemic subjects; 22 in study 1 and 15 in study 2.

MAIN OUTCOME MEASURES

Plasma lipids, plasma sterols, plasma carotenoids and tocopherols.

RESULTS

Study 1-median LDL cholesterol was reduced by the sterol esters (-13.6%; P<0.001 by ANOVA on ranks; P<0.05 by pairwise comparison) and by stanols (-8.3%; P=0.003, ANOVA and <0.05 pairwise comparison). With sterol esters plasma plant sterol levels rose (35% for sitosterol, 51% for campesterol; P<0.001); plasma lathosterol rose 20% (P=0.03), indicating compensatory increased cholesterol synthesis. With stanols, plasma sitosterol fell 22% (P=0.004), indicating less cholesterol absorption. None of the four carotenoids measured in plasma changed significantly. In study 2, median LDL cholesterol rose 6.5% with dairy spread and fell 12.2% with the sitosterol ester fortified spread (P=0.03 ANOVA and <5% pairwise comparison).

CONCLUSION

1. Plant sterol esters and non-esterified stanols, two-thirds of which were incorporated into low-fat foods, contributed effectively to LDL cholesterol lowering, extending the range of potential foods. 2. The LDL cholesterol-raising effect of butter fat could be countered by including sterol esters. 3. Plasma carotenoids and tocopherols were not reduced in this study.

SPONSORSHIP

Meadow Lea Foods, Australia.

Effects of n-3 fatty acids on growth and survival of J774 macrophages

To further understand potential mechanisms underlying the protective effects of eicosapentanoic acid (EPA) against atherosclerosis, J774 macrophages were used to explore cellular responses to growth in the presence of PUFA in vitro. Clonogenic assays indicated that 15 microg/ml of EPA killed over 90% of J774 populations. Docosapentaenoic acid (DPA) was more cytotoxic than either EPA or docosahexaenoic acid (DHA). EPA was shown to be elongated to DPA. Cytotoxicity induced by EPA was not inhibited by the presence of alpha-tocopherol (a-toc) in the medium. Immunological screening for caspase enzymes and microscopic examination indicated that apoptosis was not the major cause of cell death. Proliferation assays demonstrated that total cell numbers of EPA-treated cells were not significantly different to control cells. Increasing does of EPA were correlated with increasing levels of intracellular malondialdehyde (MDA). These observations suggest that EPA may influence the growth parameters of macrophages whilst inducing moderately elevated levels of oxidative stress.

Lack of association between temporal lobe epilepsy and a novel polymorphism in the alpha 2 subunit gene (ATP1A2) of the sodium potassium transporting ATPase

Genetic linkage studies in rodents and humans have identified specific chromosomal regions harboring seizure susceptibility genes. We have identified a novel polymorphism in the human alpha 2 subunit gene (ATP1A2) of the sodium potassium transporting ATPase (NaK-pump), a candidate gene for human temporal lobe epilepsy (TLE) based on its chromosomal location and function in ion homeostasis. The polymorphism consists of a four base pair insertion 12 base pairs upstream of the start of exon 2. We performed an association study between this polymorphism and TLE. Our study did not find a significant difference in the frequency of this polymorphism between TLE patients and controls, indicating that this variation is not a major susceptibility factor. However, since the number of patients studied so far is small and the functional consequence of the polymorphism is unknown, the variation may yet be found to play a minor role in increased risk for seizure susceptibility. In contrast to the findings in TLE patients and controls, we did find a significant difference in the frequency of the variation between African Americans and persons of European descent. This finding demonstrates the potential effect of population stratification on studies of this type and supports the growing use of parental and familial samples for controls in association studies. Further study of this polymorphism is warranted as it may be involved in other disease processes for which there are known ethnic-specific susceptibilities. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:79-83, 2000.

Effects of menopause and hormone replacement therapy on plasma lipids, lipoproteins and LDL-receptor activity

A cross-sectional study of ninety six women was conducted to examine the effect of menopause and hormone replacement therapy (HRT) on plasma lipids, lipoproteins and oxidation of low density lipoproteins. The sample consisted of 26 premenopausal women, 26 postmenopausal women taking no replacement hormones and 43 postmenopausal women on hormone replacement therapy. Postmenopausal women not taking replacement hormones had significantly higher plasma cholesterol, low density lipoprotein (LDL) cholesterol and lipoprotein[a] (Lp[a]) levels compared to premenopausal women or postmenopausal women on HRT [6.00 +/- 0.15, 5.36 +/- 0.17 (P < 0.01), 5.63 +/- 0.13 (P < 0.05) mmol/l, respectively for total cholesterol; 4.13 +/- 0.15, 3.64 +/- 0.15 (P < 0.05), 3.82 +/- 0.12 (P < 0.05) mmol/l, respectively for LDL-cholesterol; 48.19 +/- 9.90, 26.59 +/- 5.53 (P < 0.03), 25.12 +/- 4.62 (P < 0.03) mg/dl, respectively for Lp[a]]. The differences in LDL cholesterol concentrations were inversely related to changes in LDL receptor activity (r = -0.27, P < 0.01). HRT use was found to be associated with a significantly smaller LDL particle size. Plasma triglyceride was significantly higher in women on HRT (1.16 +/- 0.07 mmol/l) than in the premenopausal group (0.96 +/- 0.07) or postmenopausal group not using HRT (0.87 +/- 0.06). There were no differences in LDL oxidation between the groups when LDL was oxidised in the presence of copper. Nor was there any difference in the uptake of copper-oxidised or macrophage-modified LDL into J774 macrophages. These results confirm the effect of menopause and exogenous hormones on plasma lipids and lipoproteins, and suggest that HRT modifies the activity of the LDL receptor. Hormone replacement did not appear to protect LDL from oxidation.

The isoflavone genistein inhibits copper and peroxyl radical mediated low density lipoprotein oxidation in vitro

Oxidation of low density lipoprotein (LDL) is implicated in the development of atherosclerosis and dietary antioxidants may provide a useful therapy in the prevention of LDL oxidation and atheroma development. The aim of these experiments was to investigate the antioxidant activity of the soybean isoflavone, genistein, in in vitro models of LDL oxidation. Genistein inhibited copper-mediated oxidation of LDL in a concentration-dependent manner by lengthening the time for conjugated diene formation (54.1 +/- 5.1 min in control LDL and 107.1 +/- 1.8 min with 5 micromol/l genistein, P<0.001) and decreasing the oxidation rate (14.4 +/- 1.9 nmol conjugated diene/mg LDL protein/min in control LDL and 7.4 +/- 1.1 nmol conjugated diene/mg LDL protein/min with 5 micromol/l genistein, P<0.001). Peroxy radical (azo-initiated) oxidation of LDL was significantly inhibited by 200 micromol/l genistein as indicated by: (i) increase in the time required for malondialdehyde (MDA) formation (7 h incubation compared to 3 h incubation with control LDL), (ii) 32, 44 and 46% decreases in MDA concentration compared to control samples following 3, 4 and 5 h incubation, respectively and (iii) decrease in relative electrophoretic mobility (REM) of LDL. Incorporation of genistein into LDL and its resultant antioxidant activity was also investigated. LDL was isolated from plasma which had been pre-incubated with 25. 50 or 100 micromol/l genistein at 37 degrees C for 24 h. Approximately 3-4% of genistein present in plasma was incorporated into LDL, however copper-mediated oxidation of control LDL and LDL isolated from plasma pre-incubated with genistein was not significantly different.

Soy isoflavones improve systemic arterial compliance but not plasma lipids in menopausal and perimenopausal women

The possibility that the heightened cardiovascular risk associated with the menopause, which is said to be ameliorated by soybeans, can be reduced with soy isoflavones was tested in 21 women. Although several were perimenopausal, all have been included. A placebo-controlled crossover trial tested the effects of 80-mg daily isoflavones (45 mg genistein) over 5- to 10-week periods. Systemic arterial compliance (arterial elasticity), which declined with age in this group, improved 26% (P < .001) compared with placebo. Arterial pressure and plasma lipids were unaffected. The vasodilatory capacity of the microcirculation was measured in nine women; high acetylcholine-mediated dilation in the forearm vasculature was similar with active and placebo treatments. LDL oxidizability measured in vitro was unchanged. Thus, one important measure of arterial health, systemic arterial compliance, was significantly improved in perimenopausal and menopausal women taking soy isoflavones to about the same extent as is achieved with conventional hormone replacement therapy.

Red wine and fractionated phenolic compounds prepared from red wine inhibit low density lipoprotein oxidation in vitro

The oxidative modification of low density lipoproteins (LDL) has been implicated in the development of atherosclerosis. This study examined the effect of red wine, ethanol and red wine stripped of phenols on copper-mediated and azo-initiated LDL oxidation. Red wine containing phenolic compounds (0.025-20 mg/l gallic acid equivalents) increased the lag time of conjugated diene formation, inhibited the generation of thiobarbituric acid reactive substances (TBARS) and decreased the relative electrophoretic mobility of LDL in a concentration-dependent manner. These changes were not apparent in LDL incubated with ethanol or red wine stripped of phenols. In other experiments, red wine (75 mg/l gallic acid equivalents) was incubated with plasma at 37 degrees C for 3 h. The LDL isolated from this plasma displayed a 60% increase in lag time following copper-mediated oxidation. Uptake of this LDL by cultured J774 macrophages was three-fold lower than control LDL. Red wine was fractionated into phenolic acids (fraction 1), catechins and monomeric anthocyanidins (fraction 2), flavonols (fraction 3) and polymeric anthocyanidins (fraction 4). All red wine fractions prolonged the time before LDL oxidation. Fraction 2 displayed a significantly greater antioxidant activity than fractions 3 and 4 (but not fraction 1) in at least one pro-oxidant model. In conclusion we have shown that antioxidant compounds in red wine can associate with LDL particles following an incubation in whole plasma, can exert an antioxidant effect and, in so doing, can inhibit the uptake of the lipoprotein by macrophages. This antioxidant effect of red wine was apparent in most of the phenolic fractions separated from wine, particularly catechins, monomeric anthocyanidins and phenolic acids.

Surviving cancer: a review of the impact and consequences

In this critical review of the literature, the author examines articles assessing the effects on patients of cancer survival. Implications for nursing practice, education and research are also discussed.

Direct gene transfer into human epileptogenic hippocampal tissue with an adeno-associated virus vector: implications for a gene therapy approach to epilepsy

PURPOSE

Virus vectors capable of transferring genetic information into human cells provide hope for improved therapy in several neurological diseases, including epilepsy. We evaluated the ability of an adeno-associated virus (AAV) vector to transfer and cause expression of a lacZ marker gene in brain slices obtained from patients undergoing temporal lobectomy for control of medically intractable seizures.

METHODS

Human brain slices were injected with an AAV vector (AAVlacZ) encoding Escherichia coli beta-galactosidase and incubated for as long as 24 h. The presence of lacZ mRNA. beta-galactosidase protein and enzymatic activity were assayed by reverse transcriptase polymerase chain reaction (rtPCR), immunocytochemistry, and the X-Gal technique, respectively.

RESULTS

AAVlacZ directed the expression in human epileptogenic brain of E. coli beta-galactosidase that had functional activity. Expression was observed in < or =5 h and was sustained for as long as the slices were viable. Morphological analysis indicated that neurons were preferentially transfected, and there was no evidence of cytotoxicity.

CONCLUSIONS

Our results confirm the feasibility of using AAV vectors to transfer genes into the human CNS and in particular, into neurons. Replacement of the lacZ gene with a functional gene modulating hippocampal neuronal physiology, might allow a localized genetic intervention for focal seizures based on the stereotaxic or endovascular delivery of such a vector system into the appropriate brain region.

Lipid content and fatty acid composition of 11 species of Queensland (Australia) fish

The fatty acid composition of 11 species of fish caught of the northeast coast of Australia was determined. No fatty acid profiles have been previously published for fish from this area nor for nine of these species. Although the percentage of polyunsaturated fatty acid (PUFA) was the same as the calculated average for Australian fish (42.3%), the percentage of n-3 fatty acids was lower (24.4 +/- 5.4% vs. 30.7 +/- 10.1%) and the n-6 fatty acids higher (16.5 +/- 4.5% vs. 11.2 +/- 5.9%), P < 0.001 in each case. The major n-3 PUFA were docosahexaenoic (15.6 +/- 6.3%) and eicosapentaenoic acid (4.3 +/- 1.1%) while the major n-6 PUFA were arachidonic (8.3 +/- 3.2%) and n-6 docosatetraenoic acid (3.1 +/- 1.3%). The second-most abundant class of fatty acid was the saturates (31.6 +/- 3.5%) while the monounsaturates accounted for 17.4 +/- 4.3% of the total fatty acids. The monounsaturate with the highest concentration was octadecenoic acid (11.8 +/- 2.6%). There was a positive correlation between the total lipid content and saturated and monounsaturated fatty acids (r = 0.675 and 0.567, respectively) and a negative correlation between the total lipid content and PUFA (r = 0.774).

Arterial compliance in obese subjects is improved with dietary plant n-3 fatty acid from flaxseed oil despite increased LDL oxidizability

The compliance or elasticity of the arterial system, an important index of circulatory function, diminishes with increasing cardiovascular risk. Conversely, systemic arterial compliance improves through eating of fish and fish oil. We therefore tested the value of high intake of alpha-linolenic acid, the plant precursor of fish fatty acids. Fifteen obese people with markers for insulin resistance ate in turn four diets of 4 weeks each; saturated/high fat (SHF), alpha-linolenic acid/low fat (ALF), oleic/low fat (OLF), and SHF. Daily intake of alpha-linolenic acid was 20 g from margarine products based on flax oil. Systemic arterial compliance was calculated from aortic flow velocity and aortic root driving pressure. Plasma lipids, glucose tolerance, and in vitro LDL oxidizability were also measured. Systemic arterial compliance during the first and last SHF periods was 0.42 +/- 0.12 (mean +/- SD) and 0.56 +/- 0.21 units based on milliliters per millimeter of mercury. It rose significantly to 0.78 +/- 0.28 (P < .0001) with ALF; systemic arterial compliance with OLF was 0.62 +/- 0.19, lower than with ALF (P < .05). Mean arterial pressures and results of oral glucose tolerance tests were similar during ALF, OLF, and second SHF; total cholesterol levels were also not significantly different. However, insulin sensitivity and HDL cholesterol diminished and LDL oxidizability increased with ALF. The marked rise in arterial compliance at least with alpha-linolenic acid reflected rapid functional improvement in the systemic arterial circulation despite a rise in LDL oxidizability. Dietary n-3 fatty acids in flax oil thus confer a novel approach to improving arterial function.

Hormone replacement therapy is associated with improved arterial physiology in healthy post-menopausal women

OBJECTIVE

Oestrogen replacement therapy is associated with a marked reduction in coronary event rates in post-menopausal women. As older age is associated with progressive arterial endothelial damage, a key event in atherosclerosis, we assessed whether hormone replacement therapy (HRT) with oestrogen alone, or oestrogen and progesterone combined, is associated with improved endothelial function in healthy women after the menopause.

DESIGN

Using high resolution external vascular ultrasound, brachial artery diameter was measured at rest and in response to reactive hyperaemia, with increased flow causing endothelium-dependent dilatation (flow-mediated dilatation).

PATIENTS

We investigated 135 healthy women; 40 were pre-menopausal (mean +/- SD age/26 +/- 6 years, group 1), 40 were post-menopausal and had never taken HRT (aged 58 +/- 3 years; group 2) and 55 were age-matched post-menopausal women who had taken HRT for > or = 2 years, from within 2 years of the menopause (aged 57 +/- 4 years; group 3). In group 3, 40 women were on combined oestrogen and progesterone and 15 on oestrogen-only HRT.

RESULTS

In group 2, flow-mediated dilatation was significantly reduced compared with group 1 (4.4 +/- 3.4 vs 9.6 +/- 3.6%, P < 0.001), consistent with a decline in arterial endothelial function after the menopause. In group 3, however, flow-mediated dilatation was significantly better than group 2 (6.2 +/- 3.3 vs 4.4 +/- 3.4%, P = 0.01), suggesting a protective effect of HRT. Flow-mediated dilatation was similar in women taking oestrogen alone and in those on combined HRT (5.5 +/- 2.8 vs 6.5 +/- 3.4%, P = 0.40).

CONCLUSIONS

Long-term HRT is associated with improved arterial endothelial function in healthy post-menopausal women. This benefit was observed in both the combined hormone replacement and unopposed oestrogen therapy groups. This may explain some of the apparent cardioprotective effect of HRT after the menopause.

Enhanced capacity of n-3 fatty acid-enriched macrophages to oxidize low density lipoprotein mechanisms and effects of antioxidant vitamins

We have investigated possible mechanisms by which n-3 fatty acid-enriched macrophages enhance the oxidation of low density lipoprotein (LDL), and the ability of antioxidant vitamins to prevent this. Macrophages were enriched with n-3 fatty acids (eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid) following incubation with fish oil. These macrophages produced large amount of TBARS in medium containing metals, and showed enhanced capacity to oxidize LDL (3-4 fold increase compared to control cells) and to accumulate the modified LDL. 5,8,11,14-eicosatetraynoic acid (ETYA, 15-lipoxygenase inhibitor) and superoxide dismutase (SOD) did not inhibit the enhanced capacity of n-3 fatty acid-enriched cells to oxidize LDL. However antioxidants, (vitamin E-enriched macrophages or vitamin C in the medium), inhibited this enhanced capacity. Medium conditioned by n-3 fatty acid-enriched cells had pro-oxidant effects on metal-initiated LDL oxidation. We conclude that n-3 fatty acid-enriched macrophages display increased oxidant capacity which is not inhibited by ETYA or SOD, and that antioxidant vitamins inhibit the enhanced capacity to oxidize LDL.

Restriction fragment length polymorphism of the apolipoprotein B gene and response to dietary fat and cholesterol

OBJECTIVE

The relationship between response to dietary fat and cholesterol, and the EcoRI restriction fragment length polymorphism (RFLP) of the apolipoprotein B(apoB) gene was examined.

DESIGN

Forty-nine free-living subjects took part in a prospective double-blind crossover dietary intervention study. The apoB EcoRI cutting site was present in five women and 18 men (E+) and absent in 15 women and 11 men (E-).

INTERVENTION

Subjects consumed a low fat (25% energy), low cholesterol (less than 200 mg/day) diet. After two weeks on this background diet (baseline) subjects were randomly assigned to consume a liquid supplement for three weeks which was either fat and cholesterol free or which contained fat (30 to 36 g) and cholesterol (650 to 780 mg). After the first three-week period subjects switched to the other supplement. Blood samples were collected for plasma lipid analysis after an overnight fast on two consecutive days at the end of baseline and on three consecutive days after each three-week supplement period.

RESULTS

There was no significant difference in response to diet between the RFLP groups. Changes in plasma total, low density lipoprotein (LDL), high density lipoprotein(HDL), HDL2 and HDL3 cholesterol or plasma triglyceride were not different between the two RFLP groups. There was a significant difference between RFLP groups for baseline HDL2-cholesterol (0.31 +/- 0.04 and 0.16 +/- 0.02 mmol/L for E- and E+ subjects, respectively) which was independent of sex and apoE genotype (P = 0.032).

CONCLUSIONS

These results indicate that the EcoRI RFLP of the apoB gene is not associated with response to dietary fat and cholesterol.

Body fat distribution is a determinant of the high-density lipoprotein response to dietary fat and cholesterol in women

We have conducted a dietary trial that addressed the factors influencing the variability in plasma lipids in response to dietary fat and cholesterol with a focus on the effects of gender and body fat distribution. Sixty-seven women and 53 men were selected so that overall men and women had a similar mean age, LDL cholesterol, and body mass index. After a 2-week low-fat period subjects were given two liquid supplements for 3 weeks each, one that contained 31 to 40 g fat and 650 to 845 mg cholesterol, and one that was fat free. Measurements included plasma lipids and lipoproteins, glucose, insulin, hepatic triglyceride lipase activity, apolipoprotein E polymorphism, and three indexes of body fat (body mass index, waist girth, and waist-hip ratio). In response to dietary fat and cholesterol supplementation only the changes in HDL cholesterol, especially in HDL2, differed between the sexes. Although on univariate analysis lipoprotein changes were predicted by baseline lipoprotein levels, body mass index, waist girth, waist-hip ratio, hepatic triglyceride lipase activity, and insulin, multiple regression showed only waist-hip ratio to predict changes in HDL2 cholesterol in women and body mass index and baseline HDL2 cholesterol in men. Changes in LDL were predicted by baseline LDL cholesterol in women and apolipoprotein E phenotype and age in men. These studies explain much of the variability that individuals show in lipoprotein changes, especially in the more desirable changes in cholesterol transport in HDL2, in response to eating saturated fat and cholesterol.

Dietary supplementation with orange and carrot juice in cigarette smokers lowers oxidation products in copper-oxidized low-density lipoproteins

OBJECTIVE

Our objective was to evaluate the effect of daily supplementation with foods high in vitamin C and beta carotene on plasma vitamin levels and oxidation of low-density lipoprotein (LDL) in cigarette smokers.

SUBJECTS

Fifteen normolipidemic male cigarette smokers who did not usually take vitamin supplements were recruited into the study.

INTERVENTIONS

Throughout the study, subjects consumed a diet rich in polyunsaturated fatty acids, which provided 36% of energy as fat: 18% from meat, dairy products, vegetable oils, and fat spreads and 18% from walnuts (68 g/day). Subjects consumed a vitamin-free drink daily for 3 weeks; then for 3 weeks they consumed daily supplements of orange juice (145 mg vitamin C) and carrot juice (16 mg beta carotene).

RESULTS

Vitamin-rich food supplements raised plasma levels of ascorbic acid (1.6-fold; P < .01) and beta carotene (2.6-fold; P < .01). Malondialdehyde, one end product of oxidation, was lower in copper-oxidized LDL after vitamin supplementation (mean +/- standard error = 65.7 +/- 2.0 and 57.5 +/- 2.9 mumol/g LDL protein before and after supplementation, respectively; P < .01). Rate of LDL oxidation and lag time before the onset of LDL oxidation were not affected by antioxidant supplementation.

CONCLUSIONS

In habitual cigarette smokers, antioxidant vitamins, which can be feasibly provided from food, partly protected LDL from oxidation despite a diet rich in polyunsaturated fatty acids.

Effects of fish oil fatty acids on low density lipoprotein size, oxidizability, and uptake by macrophages

The effect of fish oil and corn oil supplementation on plasma lipids and lipoproteins and on low density lipoprotein (LDL) oxidation was examined in 20 treated hypertensive subjects. The randomized double-blind crossover study consisted of two 6-week interventions with 4 g/day of a highly purified fish oil or corn oil. Fish oil significantly (-24%, P < 0.01) reduced plasma triglyceride, and increased LDL-cholesterol (+6%, P < 0.01 compared to corn oil). LDL particles were larger (P < 0.01) after fish oil compared to baseline and LDL size was inversely correlated with plasma triglyceride (P < 0.001) both before and after fish oil supplementation, and positively correlated with high density lipoprotein cholesterol (P < 0.01). Fish oil reduced lag time before onset of copper-induced LDL oxidation (-25%, P < 0.001) and significantly increased production of thiobarbituric acid-reactive substances (TBARS) during oxidation, compared with corn oil. Corn oil had no significant effect on lag time and oxidation rate. Fish oil increased macrophage uptake of copper-oxidized LDL and of macrophage-modified LDL. Corn oil was without effect. Additionally, macrophages that were supplemented with fish oil fatty acids in vitro displayed a significantly (P < 0.001) higher capacity to oxidize LDL than either control cells or cells supplemented with corn oil fatty acids. We conclude that from the standpoint of atherosclerosis, fish oil fatty acids adversely raise the susceptibility of LDL to copper-induced and macrophage-mediated oxidation but that the increase in plasma LDL cholesterol concentration reflects an increase in size that may be favorable.

Effects of supplementing with vitamin E on the uptake of low density lipoprotein and the stimulation of cholesteryl ester formation in macrophages

Vitamin E supplementation has been reported to protect low density lipoprotein (LDL) from copper-induced oxidation and macrophage-mediated oxidation. We investigated the effect of in vitro vitamin E enrichment of LDL on the accumulation of [3H]cholesteryl ester (CE)-LDL and stimulation of cholesteryl ester formation in J774 macrophages. Vitamin E supplementation prolonged lag time (2.9-fold) before the initiation of copper-induced LDL oxidation. LDL, preincubated with 5 microM copper or with macrophages in Ham's F10 medium, accumulated in macrophages much more than did native LDL. However, following vitamin E enrichment, LDL accumulation was significantly reduced following oxidative stress. Vitamin E-enriched LDL also reduced the stimulation of cholesteryl ester formation in macrophages. Moreover, vitamin E enrichment of macrophages reduced the ability of the cells to oxidize LDL. The present results indicate that vitamin E supplementation protects LDL against copper-induced and macrophage-mediated oxidation, inhibits oxidation-dependent accumulation of LDL in macrophages, and prevents stimulation of cholesteryl ester formation in macrophages. Additionally we have provided evidence that intra-cellular enrichment with vitamin E prevents oxidative modification of LDL by macrophages.

Reduction of blood pressure and plasma triglycerides by omega-3 fatty acids in treated hypertensives

OBJECTIVE

To assess the effects of omega-3 (n-3) fatty acid supplementation on blood pressure and plasma lipids in hypertensives treated with diuretics or beta-blockers.

DESIGN

Double-blind placebo-controlled cross-over trial consisting of a 4-week run-in phase and two 6-week intervention phases.

PATIENTS

A total of 43 patients of either sex taking a beta-blocker only (n = 29), a diuretic only (n = 3) or a beta-blocker plus diuretic (n = 11) for hypertension were recruited from general practice. One patient from the latter group was withdrawn.

METHODS

Seated blood pressure was measured every 2 weeks in the clinic with a Dinamap. After the run-in phase, participants were randomly assigned to take a supplement of either Omacor (85% n-3 fatty acid concentrate) or corn oil (four 1-g capsules/day) for 6 weeks, after which they crossed over to the other supplement. Fasted blood samples were taken at the end of each phase for lipid analysis.

MAIN OUTCOME MEASURES

The within-individual differences in systolic and diastolic pressure and plasma lipids between Omacor and corn oil treatment.

RESULTS

Systolic/diastolic blood pressures measured during the run-in phase were normal (132 +/- 2/76 +/- 1 mmHg, n = 42) but decreased further with n-3 fatty acid supplementation. The mean within-individual difference in blood pressure compared with corn oil supplementation was 3.1 +/- 1.0/1.8 +/- 0.6 mmHg (P < 0.01). This was accompanied by a 21% reduction in plasma triglycerides (P < 0.01) and a 15% increase in high-density lipoprotein-2 cholesterol (P < 0.01) but there were no significant differences in total or low-density lipoprotein cholesterol.

CONCLUSION

The antihypertensive and hypotriglyceridaemic effects of n-3 fatty acid supplementation seen in the present study suggest that it may be a useful adjunct to antihypertensive therapy with beta-blockers or diuretics.

Partial replacement of saturated fatty acids with almonds or walnuts lowers total plasma cholesterol and low-density-lipoprotein cholesterol

Sixteen normolipidemic male volunteers aged 41 +/- 9 y (mean +/- SD) consumed a diet providing 36% of energy as fat (92 g fat/d) for 9 wk. A daily supplement of nuts (providing half of the total fat intake) was provided against a common background diet. In the first 3-wk period the background diet was supplemented with raw peanuts (50 g/d), coconut cubes (40 g/d), and a coconut confectionary bar (50 g/d), designed to provide 47 g fat with a ratio of polyunsaturated to monounsaturated to saturated fatty acids (P:M:S) to match the Australian diet (reference diet). During the following 3 wk the background diet was supplemented with monounsaturated fatty acid-rich raw almonds (84 g/d), equivalent to 46 g fat, and during the final 3-wk period the background diet was supplemented with polyunsaturated fatty acid-rich walnuts (68 g/d), equivalent to 46 g fat. Compared with the reference diet there were significant reductions in total and LDL cholesterol, 7% and 10%, respectively, after supplementation with almonds, and 5% and 9%, respectively, after supplementation with walnuts.

Plasma cholesteryl ester transfer protein activity is increased when trans-elaidic acid is substituted for cis-oleic acid in the diet

The trans isomer of oleic acid (elaidic acid) increases low density lipoprotein (LDL) cholesterol and decreases high density lipoprotein (HDL) cholesterol in man. One possible mechanism for this effect is that trans fatty acids increase plasma cholesteryl ester transfer protein (CETP) activity. We examined the effect of dietary trans fatty acids on activity of this protein in plasma from 27 men in a double blind crossover comparison. The background diet, containing 15% energy as fat from dairy products, meat, bread and cereals, was supplemented with oleic or elaidic acid providing a further 20% energy. The elaidic supplement provided about 6% energy as trans fatty acid. Activity of CETP in plasma was significantly higher (P < 0.001) after the elaidic acid-rich diet (23.95 +/- 1.26%) compared with the diet enriched with oleic acid (19.61 +/- 0.89%). A significant correlation between the change in plasma trans 18:1 fatty acids and the change in plasma CETP activity (r = 0.58, P < 0.002) was independent of changes in LDL-cholesterol. The increase in CETP activity was in turn significantly correlated with a fall in HDL-cholesterol among subjects during the elaidic acid-rich period (r = -0.57, P < 0.01). We have shown that CETP demonstrates substrate specificity and that the increase in activity with dietary trans fatty acids may contribute to a more atherogenic lipoprotein profile.

The low-density lipoprotein receptor and cholesterol synthesis are affected differently by dietary cholesterol in the rat

In the hamster and the rabbit, the low-density lipoprotein (LDL) receptor and cholesterol synthesis are coordinately downregulated by dietary cholesterol. In the rat, cholesterol synthesis is downregulated but LDL kinetic studies suggest that the LDL receptor is not. The aim of this study was to determine the effect of dietary cholesterol on the expression of the hepatic LDL receptor in the rat. Young (2 months) hooded and albino Wistar rats and older (9 months) Sprague-Dawley rats were used because of their reported different propensities to develop hypercholesterolaemia when fed cholesterol. Hepatic LDL receptor activity was measured using a dot blot assay with LDL-gold and LDL receptor mass was measured using an electroblot assay with a polyclonal antibody. Dietary cholesterol had no effect on the plasma cholesterol concentration in both strains of young Wistar rats but increased it in the older Sprague-Dawley rats. Cholesterol synthesis as measured with 3H2O or as indicated by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity or the ratio of plasma lathosterol to cholesterol was effectively downregulated by dietary cholesterol (1% w/w) in all three strains. In contrast, dietary cholesterol increased both hepatic LDL receptor activity and mass in the young Wistar rats and had no effect on either receptor activity or mass in the older Sprague-Dawley rats. Increases in receptor activity occurred despite increases in hepatic cholesterol especially when cholic acid was added to the cholesterol diet. The effect was systemic because CL 277082, an inhibitor of intestinal cholesterol absorption, prevented the increase in LDL receptor activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidant vitamins and low-density-lipoprotein oxidation

Low-density-lipoprotein (LDL) oxidation was examined in 22 subjects (10 men, 12 women) after a daily dose of 18 mg beta-carotene, 900 mg vitamin C, and 200 mg alpha-tocopherol for 6 mo. Control subjects (12 men, 11 women) took no vitamin supplements. After 3-mo supplementation plasma concentrations of beta-carotene, alpha-tocopherol, and ascorbic acid increased fivefold (P < 0.001), 55% (P < 0.01), and 27% (P < 0.05), respectively. There was no difference from baseline in rate of oxidation or total amount of conjugated diene produced between subjects taking or not taking vitamins. Malondialdehyde in LDL before and after oxidation was not different between the two groups. Lag time before the onset of oxidation was significantly lengthened after antioxidant supplementation (28% and 35% after 3 and 6 mo, respectively, P < 0.001). There was a significant independent correlation between percent change in lag time and percent change in plasma alpha-tocopherol (r = 0.47, P < 0.01).

Dietary non-starch polysaccharides interact with cholesterol and fish oil in their effects on plasma lipids and hepatic lipoprotein receptor activity in rats

Male rats were fed the non-starch polysaccharides pectin, methylcellulose or guar gum with corn oil or with 60% of the corn oil replaced by fish oil. They were also fed these diets with or without cholesterol (+ cholic acid). Plasma total cholesterol concentration was higher overall in rats fed cholesterol and lower in those fed fish oil or fish oil + cholesterol. Plasma triacylglycerols were lower in rats fed fish oil with or without cholesterol. Hepatic LDL receptor activity was higher overall in rats fed fish oil or fish oil + cholesterol than in those fed cholesterol. Liver HDL receptor was lower overall in rats fed fish oil or cholesterol. Type of non-starch polysaccharide influenced these dietary effects so that in cholesterol-fed rats plasma cholesterol was highest in those fed methylcellulose, intermediate in those fed guar gum and in those fed pectin was unchanged from concentrations in rats fed pectin without cholesterol. Fish oil feeding lowered plasma cholesterol concentration in rats fed pectin or methylcellulose but not in those fed guar gum. Plasma triacylglycerols were lower in rats fed fish oil and all three non-starch polysaccharides, but concentrations were similar in rats fed pectin + fish oil + cholesterol and in those fed pectin. In rats fed methylcellulose + cholesterol and any non-starch polysaccharide + fish oils, HDL receptor activity was uniformly lower than in rats fed pectin, methylcellulose or guar gum. Low density lipoprotein receptor activity was higher in rats fed pectin + fish oil or pectin + fish oil + cholesterol than in rats fed pectin.

Oxidation of low-density lipoproteins: intraindividual variability and the effect of dietary linoleate supplementation

Low-density lipoprotein (LDL) oxidation was measured in vitro to determine intraindividual variability and to relate oxidation to linoleic acid enrichment. Intraindividual variability was determined for eight subjects on 3 consecutive days after 14 d on a fixed diet. Coefficients of variation were 7.49 +/- 1.50%, 6.58 +/- 1.16%, and 4.58 +/- 0.77% for oxidation rate, lag time, and diene concentration, respectively. In the second study 12 normolipidemic men consumed a daily diet supplement containing 35 g linoleate-rich oil in one period and 35 g oleate-rich oil in the other period (2 x 3 wk crossover). LDL oxidized faster after the linoleate diet than after the oleate diet (mean +/- SE: 16.42 +/- 0.85 and 13.16 +/- 0.68 nmol diene.mg LDL protein-1.min-1, respectively, P < 0.02) and produced more conjugated diene (416 +/- 12.60 and 379.29 +/- 11.06 nmol/mg protein, respectively, P < 0.05) in proportion to the increase in LDL linoleate (r = 0.698, P < 0.001 and r = 0.618, P < 0.01 for rate and diene concentration, respectively). Lag time before onset of oxidation was not significantly altered by the linoleate-rich diet.

Plasma lipoprotein lipid and Lp[a] changes with substitution of elaidic acid for oleic acid in the diet

The effect of additional dietary trans fatty acids (7% energy) on plasma lipids was assessed in a double-blind comparison of four separate diets: 1, enriched with butter fat (lauric-myristic-palmitic); 2, oleic acid-rich; 3, elaidic acid-rich; 4, palmitic acid-rich. The total dietary period was 11 weeks and comprised normal foods plus specific fat supplements. In 27 mildly hypercholesterolemic men, total and LDL cholesterol were significantly lower during the 3-week oleic acid-rich diet, and were similar during the other three diets. For the four diets LDL cholesterol levels were in mg/dl: 1, 163; 2, 151; 3, 165; 4, 161. HDL cholesterol was significantly higher with the palmitic acid-rich diet, 42 mg/dl, compared with elaidic acid, 38 mg/dl, which in turn was not lower than with oleic acid, 38 mg/dl. Plasma elaidic acid concentration rose seven-fold with the trans fatty acid diet but did not increase the vulnerability of LDL to oxidative change. The elaidic acid-rich diet led to significant elevations in the level of Lp[a] compared to all the other test diets. The Lp[a] level increased to 296 +/- 220 U/l in the elaidic acid-rich period from 235 +/- 182 (mean +/- SD) in the first ("butter") period (P less than 0.001) compared with 249 +/- 204 in the palmitic acid period (P less than 0.001) and 236 +/- 201 in the oleic acid period (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma cholesterol-lowering potential of edible-oil blends suitable for commercial use

We tested semihardened blends of edible oils, suitable for commercial food manufacture, with a lower-than-conventional saturated fatty acid content, for their effects on plasma cholesterol. Twenty-six mildly hypercholesterolemic men took part in a double-blind crossover experiment in which two test blends were compared with two control dietary periods [which resembled the Australian fat intake: proportions of polyunsaturated, monounsaturated, and saturated fatty acids (PMS) 0.4:0.9:1]. PMS in the test diets was approximately 0.8:1.3:1 and resulted in significantly lower LDL-cholesterol concentrations (reductions of less than or equal to 7.7%). HDL cholesterol and plasma triglyceride were unchanged. The trans fatty acid (mainly elaidic) content of the blends was 16%, raising its contribution to energy by 4% but without apparent effect on LDL and HDL concentrations. Provided the overall ratio of linoleic acid to palmitic acid in commercial edible-oil blends exceeds that in the prevailing national diet, partial hydrogenation will not negate the LDL-lowering potential.

Lipid, lipoprotein, and hemostatic effects of fish vs fish-oil n-3 fatty acids in mildly hyperlipidemic males

The effects of fish and fish oil on lipids, hemostasis, and blood pressure were compared in 25 mildly hyperlipidemic men who received 4.5 g eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) daily for 5 wk. Six additional subjects served as controls. Fish and fish oil lowered plasma triglycerides 20% and 28% and very-low-density-lipoprotein (VLDL) triglycerides 42% and 52%, respectively (all P less than 0.05 compared with control). High-density-lipoprotein (HDL) cholesterol increased by 10% and 9%, with 34% and 32% increases in the proportion of HDL2 particles for fish and fish oil, respectively. Changes in total cholesterol, LDL cholesterol, apolipoprotein B, and blood pressure with fish and fish oil were not significantly different from changes for the control diet. The fish lowered fibrinogen (15.7%) and thromboxane (10.5%) and increased bleeding time (10.8%) (P less than 0.05 compared with control). Eating fatty fish and fish oil produced comparable lipid and lipoprotein changes, but only the fish improved hemostatic factors.

Incorporation and effects of dietary eicosapentaenoate (20:5(n-3)) on plasma and erythrocyte lipids of the marmoset following dietary supplementation with differing levels of linoleic acid

The effect of dietary eicosapentaenoic acid (EPA, 20:5(n-3), as the ethyl ester) on plasma lipid levels and the incorporation of EPA into erythrocyte and plasma lipids were investigated in the marmoset monkey. Marmosets were fed high mixed-fat diets (14.5% total fat) supplemented with or without 0.8% EPA for 30 weeks. Markedly elevated plasma cholesterol (16.4 mmol/l) was induced by an atherogenic-type diet but with EPA supplementation, plasma cholesterol increased to only 6.6 mmol/l. Plasma triacylglycerol levels were not elevated with an atherogenic type diet. Substantial EPA incorporation was evident for plasma phospholipid, triacylglycerol and cholesterol ester fractions. The proportion of docosapentaenoic acid (22:5(n-3)) but not docosahexaenoic acid (22:6(n-3)) was also elevated in these plasma lipid fractions. Greatest incorporation of EPA occurred when it was administered with an atherogenic type diet having a P:M:S (polyunsaturated:monounsaturated:saturated) fatty acid ratio of about 0.2:0.6:1.0 in comparison to the control diet of 1.0:1.0:1.0. Incorporation of EPA and 22:5(n-3)) into erythrocyte phospholipids was also apparent and this was at the expense of linoleic acid (18:2(n-6)). These results in the marmoset highlight both the cholesterol-lowering properties of EPA and the extent of its incorporation into plasma lipids and erythrocyte membrane phospholipids with far greater incorporation occurring when the level of dietary linoleic acid was reduced.

Relationship between sensitivity to dietary fat and dietary cholesterol

A group of 56 hypercholesterolemic and normocholesterolemic men and women were given approximately 700 mg a day of egg yolk cholesterol in a double-blind, crossover study while they were on a background diet containing approximately 30% of energy as fat. Overall there was a 0.23 mmol/l rise in plasma cholesterol (3.7%, p less than 0.001) after 4 weeks, a 0.19 mmol/l rise in low density lipoprotein (LDL) cholesterol (4.9%, p = 0.002), and a 0.07 mmol/l rise in high density lipoprotein (HDL) cholesterol (5.4%, p less than 0.001). Plasma triglycerides fell by 0.07 mmol/l (5.1%). Normocholesterolemic individuals (plasma cholesterol less than 5.2 mmol/l) experienced small, nonsignificant rises of 0.06, 0.02, and 0.05 mmol/l in total, LDL, and HDL cholesterol, respectively. Hypercholesterolemic subjects were classified on the basis of their response to a low fat diet. Diet-sensitive subjects were defined by a greater than 10% fall in plasma cholesterol on a 25% fat, low cholesterol (less than 200 mg/day) diet. These individuals were found to be more responsive to the effect of dietary cholesterol than were diet-insensitive subjects; the respective changes in the two groups were rises of 0.36 mmol/l versus 0.19 mmol/l in plasma cholesterol (p = 0.06) and rises of 0.30 versus 0.15 mmol/l in LDL cholesterol (p = 0.06). In addition to elevating HDL cholesterol by 0.09 mmol/l and 0.07 mmol/l, respectively, dietary cholesterol also produced an increase in the proportion of HDL2, from 40% to 44% of HDL protein (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a high fat/cholesterol diet with or without eicosapentaenoic acid on plasma lipids, lipoproteins and lipid transfer protein activity in the marmoset

Marmosets fed a diet supplemented with 0.2% cholesterol and 10% sheep fat (by weight) developed hypercholesterolemia with a 4-fold increase in plasma cholesterol (4.28 +/- 0.57-16.38 +/- 4.22 mmol/l, mean +/- SD, P less than 0.001). This was due mainly to a 5-fold increase in the intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) fraction (d = 1.006-1.063 g/ml). The proportion of plasma cholesterol in high density lipoproteins (HDL) decreased from 56% to 25% although HDL cholesterol increased from 2.40 +/- 0.42 to 4.09 +/- 0.92 mmol/l (P less than 0.001), and HDL particle radius increased from 5.10 +/- 0.18 nm to 6.06 +/- 0.73 nm (P less than 0.05). Plasma lipid transfer protein (LTP) activity increased 2.5-fold in whole plasma and 2-fold in lipoprotein-deficient plasma. The atherogenic lipoprotein profile was attenuated by adding 0.8% eicosapentaenoic acid (EPA, 20:5 n - 3, as the ethyl ester) to the atherogenic diet. Plasma cholesterol increased only 55% to 6.64 +/- 2.55 mmol/l with only an 80% increase in lipoproteins in the d = 1.006-1.063 g/ml fraction and a more favourable proportion of plasma cholesterol in HDL (44%) than without EPA. LTP activity was reduced to 1.7-fold above control in whole plasma by addition of EPA to the atherogenic diet. There was a positive correlation between plasma cholesterol and LTP activity in whole plasma (r = 0.89, P less than 0.001) and in lipoprotein-deficient plasma (r = 0.67, P less than 0.001). EPA therefore attenuated some of the adverse effects of a 0.2% cholesterol, 10% sheep fat diet on plasma lipids and lipoproteins and induced a less atherogenic profile.

Effect of fish oil on lipoproteins, lecithin:cholesterol acyltransferase, and lipid transfer protein activity in humans

A group of 33 mildly hypercholesterolemic men were stratified into three groups on diets closely matched except for the polyunsaturated fatty acid supplement. The first group received 14 g/day of linoleic acid (safflower oil); the second group, 9 g of alpha-linolenic acid (linseed oil); and the third group, 3.8 g of n-3 fatty acids (fish oil). Only fish oil lowered plasma triglycerides (by 24% at 6 weeks, p less than 0.05 compared to safflower oil). Very low density lipoprotein (VLDL) apoprotein (apo) B, triglyceride, and cholesterol all fell significantly with the fish-oil diet (p less than 0.01). Low density lipoprotein (LDL) cholesterol fell by 0.18 and 0.10 mmol/l, respectively, with the safflower-oil and linseed-oil diets, but rose by 0.24 mmol/l with the fish-oil diet (p less than 0.05). There was a strong correlation between the changes in VLDL triglyceride and LDL cholesterol with the fish-oil diet (r = -0.84, p less than 0.002). High density lipoprotein (HDL) cholesterol fell slightly in all three groups (p less than 0.02 with the linseed-oil diet only). However, the apo A-I/A-II ratio rose by 5% (p less than 0.05), and the HDL2/HDL3 protein ratio increased by 28% with the fish-oil diet (p less than 0.005). Fish oil reduced the capacity for transfer of cholesteryl ester between LDL and HDL by 23% (p less than 0.02 compared to baseline), reduced plasma lecithin:cholesterol acyltransferase activity by 21% (p less than 0.05), and reduced maximal stimulated thromboxane production by 9% (p less than 0.05). Thus fish oil produced three potentially beneficial changes: significant decreases in VLDL concentration and in thromboxane production and an increase in the HDL2/HDL3 ratio. The increase in the average HDL particle size probably reflected reduced cholesteryl ester acceptor capacity within the smaller pool of VLDL, as well as the decline in lipid transfer activity in plasma involving transfer protein itself, LDL, and HDL.

Effects of blocking plasma lipid transfer protein activity in the rabbit

Plasma lipid transfer protein activity was completely blocked in rabbits for up to 48 h by infusion with goat antibody to rabbit lipid transfer protein. Lipid transfer protein activity in plasma of control animals, infused with antibody from a non-immune goat, decreased during the experiment but was never less than 50% of pre-infusion levels. During the period that lipid transfer protein activity was completely blocked, there were changes in high-density lipoprotein composition (expressed as % by weight) with a reduction in triacylglycerol from 8.4 +/- 2.4% to 1.0 +/- 0.2% (P less than 0.05) and an increase in esterified cholesterol from 10.7 +/- 1.7% to 14.5 +/- 0.3% (P less than 0.1). In conjunction with the observed changes in high-density lipoprotein composition, there was an increase in high-density lipoprotein particle size from a mean radius of 4.7 to 5.4 nm. The change in composition and particle size was not observed in high-density lipoproteins from control animals. There was a change in the distribution of plasma cholesterol in control animals, with a fall in the proportion of cholesterol in high-density lipoproteins (P less than 0.02) and consequently an increase in the proportion of cholesterol in low-density lipoproteins (P less than 0.02). However, the distribution of plasma cholesterol in animals in which lipid transfer protein activity was inhibited was maintained at original levels during the period of inhibition. Consequently, in these animals, there was a less atherogenic distribution of cholesterol during the period of lipid transfer protein inhibition when compared with control animals. The changes observed in lipoproteins, in the absence of lipid transfer protein activity, demonstrate that lipid transfer protein modifies lipoproteins in vivo and appears to contribute to a more atherogenic lipid profile.

Immunoprecipitation of lipid transfer protein activity by an antibody against human plasma lipid transfer protein-I

Two lipid transfer proteins, designated lipid transfer protein-I (Mr 69 000) and lipid transfer protein-II (Mr 55 000), each of which facilitates the transfer of radiolabelled cholesteryl ester, triacylglycerol and phosphatidylcholine between plasma lipoproteins, were purified from human plasma. Immunoglobulin G was prepared from goat antiserum to human lipid transfer protein-I (i.e., anti-human LTP-I IgG). The progressive addition of anti-human LTP-I IgG to buffered solutions containing either a highly purified mixture of human lipid transfer protein-I and lipid transfer protein-II, or highly purified rabbit lipid transfer protein (Abbey, M., Calvert, G.D. and Barter, P.J. (1984) Biochim. Biophys. Acta 793, 471-480) resulted in specific immunoprecipitation and the removal of increasing amounts, up to 100%, of cholesteryl ester, triacylglycerol and phosphatidylcholine transfer activities. However, similar precipitation studies on human and rabbit lipoprotein-free plasma resulted in the progressive removal of all cholesteryl ester and triacylglycerol transfer activities but only 30% (human) or 20% (rabbit) of phosphatidylcholine transfer activity. In all cases more anti-human LTP-I IgG was required to precipitate rabbit lipid transfer activity than human lipid transfer activity. These results suggest that lipid transfer protein-I and lipid transfer protein-II have antigenic sites in common, allowing precipitation of both proteins by specific antibody to lipid transfer protein-I. Most plasma phosphatidylcholine transfer activity is mediated by a protein (or proteins) other than lipid transfer protein-I and lipid transfer protein-II. In lipoprotein-free plasma all cholesteryl ester and triacylglycerol transfer activity, and some phosphatidylcholine transfer activity, is mediated by lipid transfer protein-I (or lipid transfer protein-I and an antigenically similar protein, lipid transfer protein-II.

Changes in lipid and apolipoprotein composition of pig lipoproteins facilitated by rabbit lipid transfer protein

A lipid transfer protein has been purified from the lipoprotein-free fraction of rabbit plasma. Rabbit lipid transfer protein, which was purified 600-700-fold with a 4% recovery, has an apparent Mr of 68 000 and facilitates the transfer of isotopically labelled cholesteryl ester, triacylglycerol and phosphatidylcholine between low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Rabbit lipid transfer protein, which appears to be very similar to the cholesteryl ester exchange protein previously purified from human plasma, was incubated with pig plasma at 37 degrees C for up to 6 h. Analysis of very-low-density lipoprotein (VLDL, d less than 1.006 g/ml), LDL (d 1.019-1.063 g/ml) and HDL (d 1.090-1.21 g/ml) after incubation showed that lipid transfer protein had a marked effect on the composition of the lipoprotein classes. The VLDL became enriched with cholesteryl ester and depleted of triacylglycerol. The LDL and HDL became enriched with triacylglycerol. In addition to these changes in lipid composition there were also changes in apolipoprotein composition. The most prominent change in apolipoprotein distribution was a marked increase in the apolipoprotein E content of LDL which was observed only after incubation in the presence of lipid transfer protein.

Detection of lipid transfer protein activity in rabbit liver perfusate

Cholesteryl ester, triacylglycerol and phospholipid transfer activity was detected in rabbit liver perfusate after 2 h perfusions in situ. Lipoproteins were removed from the perfusate plasma by ultracentrifugation prior to hydrophobic interaction chromatography of the lipoprotein-free perfusate. The hydrophobic protein, eluted with water from a Phenyl-Sepharose column, facilitated the transfer of radiolabelled cholesteryl ester, triacylglycerol and phosphatidylcholine from low-density lipoprotein to high-density lipoprotein during 3 h incubations at 37 degrees C. These results suggest that rabbit plasma lipid transfer protein is produced by the liver.