Low Density Lipoprotein In Medium Research Articles

Short-term effects of gastric bypass versus sleeve gastrectomy on high LDL cholesterol: The BASALTO randomized clinical trial

BackgroundThere has been a substantial increase in the use of laparoscopic sleeve gastrectomy (SG) to treat morbid obesity despite observational evidence demonstrating the superiority of Roux-en-Y gastric bypass (RYGB) for reducing low-density lipoprotein (LDL) cholesterol. The main aim was to ascertain whether high LDL cholesterol levels should be considered when selecting the most appropriate surgical procedure for each patient (RYGB or SG).MethodsIn this single-center, randomized clinical trial using intention-to-treat analysis, 38 patients with severe obesity and elevated levels of LDL cholesterol were randomly assigned to undergo RYGB or SG. The primary outcome was LDL cholesterol remission at 12 months, defined as LDL cholesterol < 3.36 nmol/l without lipid-lowering medications. Secondary outcomes included changes in weight, other comorbidities, qualitative lipoprotein traits, cholesterol esters, glycoproteins, cholesterol absorption and synthesis metabolites and complications.ResultsIntention-to-treat analysis revealed that LDL cholesterol remission occurred in 66.6% of RYGB patients compared to 27.8% of SG patients (p = 0.019). Among patients completing follow-up, RYGB demonstrated superior remission (80.0% vs. 29.4%, p = 0.005). Exclusive benefits of RYGB included a reduction in large, medium, and small LDL particles. Cholesterol absorption markers showed differential behavior after both techniques: campesterol (Δ −15.2 µg/mg, 95% CI −30.2 to −0.1) decreased after RYGB, and sitosterol (Δ 21.1 µg/mg, 95% CI 0.9 to 41.2), cholestanol (Δ 30.6 µg/mg, 95% CI 14.8 to 57.9) and campesterol (Δ 18.4 µg/mg, 95% CI 4.4 to 32.3) increased after SG. No differences in weight loss, cholesterol esters, glycoproteins, cholesterol synthesis metabolites or postoperative complications were observed between techniques.ConclusionIn conclusion, RYGB is superior to SG in terms of short-term of high LDL cholesterol remission. Furthermore, RYGB also led to a greater improvement in lipoprotein parameters that confer an atherogenic profile. Therefore, the presence of elevated levels of LDL cholesterol should be considered when determining the optimal bariatric surgery procedure for each patient.Trial registrationClinicaltrials.gov number, NCT03975478).Graphical abstract

Cholesterol and low-density lipoprotein as a cause of psoriasis: Results from bidirectional Mendelian randomization.

Psoriasis is an inflammatory disease that affects many people. However, the causal effect of lipid metabolism on psoriasis has not yet been verified. This study aimed to identify the genetic relationship between serum lipid levels and psoriasis. Bidirectional two-sample Mendelian randomization (MR) was used to analyse the causal relationship between cholesterol and psoriasis. The outcome of the forward causality test was psoriasis. In the analysis of reverse causality, psoriasis was exposed, and 79 single-nucleotide polymorphisms were detected in the genome-wide association study (GWASs) database from the IEU GWASs Project. MR-Egger regression, inverse variance-weighted, weighted median, weighted mode and simple mode were used for the MR analyses. The level of triglyceride, lipase member N, chylomicrons, extremely large very low-density lipoprotein (VLDL) particles, high-density lipoprotein (HDL) cholesterol levels, cholesterol esters in large HDL, cholesterol esters in medium HDL and cholesterol esters in medium VLDL have not affected the development of psoriasis. However, total cholesterol, total free cholesterol, low-density lipoprotein (LDL) cholesterol levels, cholesterol esters in large VLDL and cholesterol esters in medium LDL were unidirectional causal effects on psoriasis. Bidirectional two-sample MR analysis indicated that high levels of total cholesterol, total free cholesterol, LDL cholesterol, cholesterol esters in large VLDL and cholesterol esters in medium LDL are genetic risk factors for psoriasis.

Causal role of lipid metabolome on the risk of ischemic stroke, its etiological subtypes, and long-term outcome: A Mendelian randomization study

Background and aimsThe lipid profile is consistently associated with coronary artery disease (CAD) and ischemic stroke (IS). However, the lipoprotein subfractions have not been deeply explored in stroke subtypes, especially in IS outcome. MethodsWe performed two-sample Mendelian randomization (MR) analysis using 92 lipid traits measured by nuclear magnetic resonance in 115,000 subjects from the UK Biobank. Data for genetic associations with IS, its subtypes, and long-term outcome (LTO) were obtained from three cohorts of European ancestry: GIGASTROKE (73,652 cases, 1,234,808 controls), GODS (n = 1791) and GISCOME (n = 6165). Results obtained using CARDIoGRAMPlusC4D were used to identify differences with CAD. ResultsGenetically determined low concentration of medium high-density lipoprotein (HDL) particles (odds ratio (OR) = 0.92, 95% CI 0.88–0.96; p = 3.6 × 10−4) and its cholesterol content (OR = 0.92, 95% CI 0.88–0.96; p = 1.9 × 10−4) showed causal associations with an increased risk of stroke. Genetic predisposition to high apolipoprotein (apo)B to apoA-I ratio was causally associated with an increased risk of IS (OR = 1.12, 95% CI 1.06–1.18, p = 1.1 × 10−4), and a highly suggestive association was found between non-esterified cholesterol in low-density lipoprotein (LDL) and increased risk of atherothrombotic stroke (LAS) (OR = 1.35, 95% CI 1.10–1.66; p = 4.0 × 10−3). Low cholesterol in small and medium LDL was suggestively associated with poor LTO. ConclusionsOur results support that low medium HDL concentration was causally associated with an increased stroke risk, while high levels of non-esterified cholesterol in LDL were suggestively associated with an increased risk of LAS and with a better LTO.

Relationship between the cholesterol and triglyceride content of lipoprotein subclasses and carotid intima-media thickness: A cross-sectional population-based study

BackgroundThe association between lipoprotein subclasses and carotid intima-media thickness (cIMT) progression has yet to be fully evaluated. We assessed which lipoprotein subclasses were associated with maximum cIMT levels in the general population. MethodsIn this study, cholesterol and triglyceride content of 20 lipoprotein subclasses were analyzed using gel permeation high-performance liquid chromatography (GP-HPLC) in 864 Japanese women and men (mean age 57 y, free of chronic liver or kidney diseases and off lipid-lowering, hormone replacement, or adrenocorticosteroid medications). Univariate and multivariate regression analyses and univariate and partial correlation analyses were performed to examine the relationships between lipoprotein subclasses and maximum cIMT levels. ResultsAfter adjusting for age, sex, systolic blood pressure, smoking, diabetes, and anti-hypertensive agents, elevated low-density lipoprotein (LDL)-2 and −3 cholesterol (particle diameter 25.5 nm and 23.0 nm, respectively; medium and small LDL) were associated with higher maximum cIMT levels in both women and men (all p for trend < 0.05). These associations were significant even after participants taking anti-diabetic or anti-hypertensive agents were excluded. No significant associations were found between any triglyceride subclasses and maximum cIMT levels. ConclusionsSmaller LDL particle cholesterol values are the most atherogenic lipoprotein parameter.

Associations of lipoprotein subclasses with risk of all-cause and cardiovascular disease mortality in individuals with type 2 diabetes: A prospective cohort study.

Although lipoproteins are well-established risk factors for cardiovascular disease (CVD) mortality, conventional measurements failed to identify lipoprotein particle sizes. This study aimed to investigate associations of lipoprotein subclasses categorized by particle sizes with risk of all-cause and CVD mortality in individuals with type 2 diabetes. This study included 6575 individuals with type 2 diabetes from the UK Biobank. Concentrations of very low-, low-, intermediate- and high-density lipoprotein [very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), intermediate-density lipoprotein and high-density lipoprotein (HDL)] particles in 14 subclasses and lipid constituents within each subclass were measured by quantitative nuclear magnetic resonance. Multivariable-adjusted Cox proportional-hazard regression models were used to estimate the hazard ratio (HR) for per standard deviation increment of log-transformed lipoprotein subclasses with risk of mortality. All p-values were adjusted by the false discovery rate method. During a median follow-up of 11.4 years, 943 deaths were documented, including 310 CVD deaths. Small HDL particles were inversely associated with CVD mortality, with HR (95% CI) of 0.78 (0.69, 0.87), whereas very large and large HDL particles were positively associated with CVD mortality with HR (95% CI) of 1.28 (1.12, 1.45) and 1.19 (1.05, 1.35), respectively. A similar pattern was observed for all-cause mortality [small HDL particle (HR, 95% CI): 0.79, 0.74-0.85; large HDL particle: 1.15, 1.07-1.24; very large HDL particle: 1.26, 1.17-1.36]. For VLDL and LDL, very small VLDL particle was positively, while medium LDL particle was inversely associated with all-cause mortality, but not associated with CVD mortality. The pattern of association with all-cause and CVD mortality for cholesterol and triglyceride within lipoprotein particles was similar to those for lipoprotein particles themselves. The associations between lipoprotein particles, particularly HDL particles, with all-cause and CVD mortality among patients with type 2 diabetes were significantly varied by particle sizes, highlighting the importance of particle size as a lipoprotein metric in mortality risk discrimination.

Lipoprotein subfractions and subclinical vascular health in middle aged women: does menopause status matter?

During midlife, women experience changes in lipoprotein profiles and deterioration in vascular health measures. We analyzed the associations of groups of lipoprotein subfractions as determined by principal component analysis (PCA) with subclinical vascular health measures in midlife women and tested if these associations were modified by menopause status. PCA was used to generate principal components (PCs) from 12 lipoprotein subfractions quantified among 545 midlife women. The associations of the identified PCs and concurrent vascular health measures were assessed using linear or logistic regressions among participants with carotid intima-media thickness (cIMT; n = 259), coronary artery calcium (n = 249), or aortic calcium (n = 248) scores. PCA generated four PCs representing groups of (1) small, medium, and large very low-density lipoproteins subclasses-very low-density lipoprotein PC; (2) very small, small, and medium low-density lipoprotein (LDL) subclasses-small-medium LDL-PC; (3) large and small high-density lipoproteins subclasses and midzone particles-high-density lipoprotein PC; and (4) large LDL and small intermediate-density lipoproteins-large LDL-PC. Small-medium LDL-PC was positively associated with cIMT, coronary artery calcium, and aortic calcium in unadjusted but not in adjusted models. Menopause status modified the positive association of the small-medium LDL-PC with cIMT (interaction P = 0.02) such that this association was stronger after versus before menopause ( P = 0.01). Carotid intimal medial thickening is positively and independently associated with small- and medium-sized LDL particles after menopause. Monitoring levels of specific lipoprotein fractions may have value in identifying midlife women at risk for developing atherosclerotic vascular disease.

Advanced lipoprotein parameters could better explain atheromatosis in non-diabetic chronic kidney disease patients.

ABSTRACTBackgroundChronic kidney disease (CKD) patients have a high burden of atheromatous cardiovascular disease (ASCVD) not fully explained by traditional lipid parameters. Lipoprotein composition and subclass particle number information could improve ASCVD risk assessment. The objective of this study is to investigate the association of advanced lipoprotein parameters with the risk of atheromatosis in a subpopulation of the NEFRONA study.MethodsThis was a cross-sectional study in 395 non-diabetic individuals (209 CKD and 186 non-diabetic and non-CKD) without statin therapy. Vascular ultrasound examination assessing 10 territories was combined with advanced lipoprotein testing performed by nuclear magnetic resonance spectroscopy. Logistic regression was used to estimate adjusted odds ratios (ORs) per 1 standard deviation increment.ResultsAtheromatosis was more prevalent in CKD patients (33.9% versus 64.6%). After adjusting for age, gender, smoking habit and CKD stage, the amount of triglycerides (TGs) within low-density lipoprotein (LDL) lipoproteins was independently and positively associated with atheromatosis [OR 1.33; 95% confidence interval (CI) 1.03–1.74; P = 0.03]. Similarly, total and medium LDL particles (LDL-Ps) showed a positive association (OR 1.29; 95% CI 1.00–1.68; P = 0.05 and OR 1.34; 95% CI 1.04–1.75; P = 0.03, respectively). TG-loaded medium LDL-Ps were higher in CKD patients compared with controls and showed an adjusted OR of 1.40 (95% CI 1.09–1.82; P = 0.01) in non-diabetic patients (CKD and non-CKD individuals). In contrast, non-diabetic CKD patients showed a similar coefficient but the significance was lost (OR 1.2; 95% CI 0.8–1.7; P = 0.359).ConclusionsNon-diabetic CKD patients showed a higher amount of TG-loaded medium LDL-Ps compared with controls. These particles were independently associated with atheromatosis in non-diabetic patients.

Metabolic Profiling of 713 Newborns and Parents in the Norwegian Mother, Father and Child Cohort Study

Background: Lipids are important for fetal development, but the determinants of cord blood lipids have scarcely been studied. We therefore aimed to describe the associations between newborn cord blood lipid and metabolic profile, and maternal and paternal lipid and metabolic profile. Methods: This study is based on 713 mother-father-newborn trios from the Norwegian Mother, Father and Child Cohort Study (MoBa) and uses data from the Medical Birth Registry of Norway. Sixty-four cord blood metabolites detected by nuclear magnetic resonance spectroscopy were analyzed. The false discovery rate (FDR) procedure was used to correct for multiple testing. Findings: We found positive associations between maternal and newborn high-density lipoprotein (HDL) cholesterol, omega 3 and 6 fatty acids, glutamine, isoleucine, leucine, valine, phenylalanine, tyrosine, glucose, citrate, creatinine, and particle concentration of medium and small HDL (0·001 ≤ qFDR ≤ 0·049). Paternal and newborn total-, low-density lipoprotein (LDL)-, HDL3-, remnant-, esterified- and free cholesterol, phosphoglycerides, cholines, phosphatidylcholines, sphingomyelins, apolipoprotein B and A1, total fatty acids, and particle concentration of intermediate-density lipoprotein, large- and medium LDL were positively associated (0·004 ≤ qFDR ≤ 0·047). Sex differences were found for many cord blood lipids. Interpretation: Several cord blood metabolites were associated with maternal and paternal metabolites and newborn sex. This may potentially affect pregnancy- and long-term outcomes. Funding: The University of Oslo; the National Advisory Unit on Familial Hypercholesterolemia, Oslo University Hospital; the Throne Holst Foundation for Nutrition Research; the Norwegian Health Association; Eckbos Legate; the Freia Corporation Medical Fund; and the Blix Foundation for the Promotion of Medical Research, Norway. Declaration of Interests: During the past five years, MPB reports grants and personal fees from Amgen, grants and personal fees from Sanofi, personal fees from MSD, personal fees from Boehringer Ingelheim, grants and personal fees from Mills AS, and grants from Kaneka, none of which are related to the content of this manuscript. JJC reports grants or personal fees from Mills DA and Amgen, none of which are related to the content of this manuscript. SMU has received research grants and/or personal fees from Mills AS, Tine DA, and Olympic Seafood, none of which are related to the content of this manuscript. KR reports personal fees from Amgen, personal fees from Mills AS, personal fees from The Norwegian Medical Association, personal fees from The Norwegian Directorate of Health, personal fees from Sanofi, personal fees from Takeda, personal fees from Chiesi, personal fees from Bayer, and personal fees from MSD, none of which are related to the content of this manuscript. JRVL has received research grants from Amryt, which are not related to the content of this manuscript. KBH has received research grants or honoraria from Mills AS, Tine SA, Olympic Seafood, Amgen, Sanofi, and Pronova, none of which are related to the content of this manuscript. LKLO, ALB, HKB, TMM, TH, PMM, and MBV declare no conflicts of interest. Ethics Approval Statement: The current study was approved by the Regional Committees for Medical and Health Research Ethics (no. 2017/1285). The study was conducted according to the principles of the Declaration of Helsinki, and all MoBa participants gave written informed consent at the time of inclusion.

Administration of eicosapentaenoic acid may alter lipoprotein particle heterogeneity in statin-treated patients with stable coronary artery disease: A pilot 6-month randomized study

BackgroundWe hypothesized that the addition of eicosapentaenoic acid (EPA) to ongoing statin therapy could change the particle heterogeneity of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles, even in stable coronary artery disease (CAD) patients. MethodsWe assigned CAD patients already receiving statin therapy to one of two groups: an EPA group (1800 mg/day; n = 30) and a control group (n = 30). A gel permeation high-performance liquid chromatography method was used to measure the particle concentration and number of lipoprotein subclasses. ResultsIn the EPA group, significant decreases of both the concentration and number of medium LDL (p = 0.0002 and 0.0001), small LDL (p = 0.0004 and 0.0005) and very small LDL (p = 0.0005 and 0.002) particles were observed. Conversely, the concentration and number of large HDL particles increased significantly (p = 0.024 and 0.048). The concentration of very large HDL particles also increased significantly (p = 0.028). Furthermore, significant correlations between the variables that showed significant changes in the LDL and HDL particle subclasses, and the EPA/arachidonic acid (AA) ratio were found. No other significant associations of lipoprotein particle heterogeneity with the serum EPA/AA ratio were noted in either the control group or the EPA group. Interestingly, univariate and multivariate regression analyses revealed that increased serum lecithin–cholesterol acyltransferase activity, a key enzyme of HDL cholesterol efflux, was a predictor for increased above-mentioned HDL particles subclasses. ConclusionsAdministration of EPA might alter both LDL and HDL particle heterogeneity, causing decreased concentration and number of smaller LDL particles and increased concentration and number of larger HDL particles. Furthermore, addition of EPA to ongoing statin therapy appears to be capable of increasing the EPA/AA ratio, which might have an anti-atherosclerotic effect on lipoprotein particle heterogeneity, even in stable CAD patients with well-controlled serum lipid levels. Clinical Trial RegistrationUMIN (http://www.umin.ac.jp/) Study ID: UMIN000010452.

Effects of red meat, white meat, and nonmeat protein sources on atherogenic lipoprotein measures in the context of low compared with high saturated fat intake: a randomized controlled trial

Dietary recommendations to limit red meat are based on observational studies linking intake to cardiovascular disease (CVD) risk together with the potential of its saturated fatty acid (SFA) content to raise low-density lipoprotein (LDL) cholesterol. However, the relation of white meat to CVD risk, and the effects of dietary protein source on lipoprotein particle subfractions, have not been extensively evaluated. We tested whether levels of atherogenic lipids and lipoproteins differed significantly following consumption of diets with high red meat content compared with diets with similar amounts of protein derived from white meat or nonmeat sources, and whether these effects were modified by concomitant intake of high compared with low SFAs. Generally healthy men and women, 21-65 y, body mass index 20-35 kg/m2, were randomly assigned to 1 of 2 parallel arms (high or low SFA) and within each, allocated to red meat, white meat, and nonmeat protein diets consumed for 4 wk each in random order. The primary outcomes were LDL cholesterol, apolipoprotein B (apoB), small+medium LDL particles, and total/high-density lipoprotein cholesterol. Analysis included participants who completed all 3 dietary protein assignments (61 for high SFA; 52 for low SFA). LDL cholesterol and apoB were higher with red and white meat than with nonmeat, independent of SFA content (P<0.0001 for all, except apoB: red meat compared with nonmeat [P=0.0004]). This was due primarily to increases in large LDL particles, whereas small+medium LDL and total/high-density lipoprotein cholesterol were unaffected by protein source (P=0.10 and P=0.51, respectively). Primary outcomes did not differ significantly between red and white meat. Independent of protein source, high compared with low SFA increased LDL cholesterol (P=0.0003), apoB (P=0.0002), and large LDL (P=0.0002). The findings are in keeping with recommendations promoting diets with a high proportion of plant-based food but, based on lipid and lipoprotein effects, do not provide evidence for choosing white over red meat for reducing CVD risk. This trial was registered at Clinicaltrials.gov as NCT01427855.

LDL particle size and composition and incident cardiovascular disease in a South-European population: The Hortega-Liposcale Follow-up Study

BackgroundThe association of low-density lipoprotein (LDL) particle composition with cardiovascular risk has not been explored before. The aim was to evaluate the relationship between baseline LDL particle size and composition (proportions of large, medium and small LDL particles over their sum expressed as small-LDL %, medium-LDL % and large-LDL %) and incident cardiovascular disease in a population-based study. MethodsDirect measurement of LDL particles was performed using a two-dimensional NMR-technique (Liposcale®). LDL cholesterol was assessed using both standard photometrical methods and the Liposcale® technique in a representative sample of 1162 adult men and women from Spain. ResultsThe geometric mean of total LDL particle concentration in the study sample was 827.2 mg/dL (95% CI 814.7, 839.8). During a mean follow-up of 12.4 ± 3.3 years, a total of 159 events occurred. Medium LDL particles were positively associated with all cardiovascular disease, coronary heart disease (CHD) and stroke after adjustment for traditional risk factors and treatment. Regarding LDL particle composition, the multivariable adjusted hazard ratios for CHD for a 5% increase in medium and small LDL % by a corresponding decrease of large LDL % were 1.93 (1.55, 2.39) and 1.41 (1.14, 1.74), respectively. ConclusionsMedium LDL particles were associated with incident cardiovascular disease. LDL particles showed the strongest association with cardiovascular events when the particle composition, rather than the total concentration, was investigated. A change in baseline composition of LDL particles from large to medium and small LDL particles was associated with an increased cardiovascular risk, especially for CHD.

Extended-release niacin reduces LDL particle number without changing total LDL cholesterol in patients with stable CAD

The importance of the number of circulating low-density lipoprotein (LDL) cholesterol particles, in addition to total LDL level, has been increasingly recognized. The effects of extended-release niacin (ERN) on LDL particle numbers have not been studied. To evaluate ERN's effects on LDL particle numbers. Fifty-four patients with stable coronary artery disease (CAD) and well-controlled LDL levels were randomly assigned to 3 months of ERN (1 g/day) or placebo in addition to their baseline medications. Lipoprotein particle number was analyzed by proton nuclear magnetic resonance spectroscopy at baseline and after 3 months. Compared to baseline, the addition of ERN had no significant effect on total LDL cholesterol levels; however, ERN decreased the number of medium and small LDL particles (P < .005). After 3 months, ERN decreased the number of medium and small LDL particles compared to placebo-treated patients (P < .05). ERN raised HDL cholesterol levels by 2.7%, significantly increased the number of large HDL particles (P < .001), and decreased the number of small HDL particles (P = .027) compared to placebo. There were no significant changes in lipid values or particle numbers in the placebo-treated patients. In patients with stable coronary artery disease and well-controlled LDL cholesterol levels, ERN reduced the number of circulating particles of the more atherogenic subtypes of LDL, despite having no effect on total LDL cholesterol levels. ERN also favorably altered the number of HDL particles. ERN-induced alterations in lipoprotein particle numbers may contribute to its anti-atherosclerotic effects, and these effects may not be evident from the standard lipid profile.

Lipoprotein subclasses and coronary artery calcium in postmenopausal women from the healthy women study

Lipoprotein subclass levels may improve the prediction of cardiovascular disease (CAD) in individuals beyond the risk assessment provided by conventional enzymatically determined lipid levels. The objective of this study was to evaluate the associations between nuclear magnetic resonance (NMR) spectroscopy–determined lipoprotein subclasses and coronary calcification in postmenopausal women, and to determine whether the associations were independent of conventional lipid measures. Coronary artery calcification (CAC) was measured by electron beam computed tomography, and lipoprotein subclasses were determined by NMR spectroscopy (Liposcience, Inc., Raleigh, NC), in 286 healthy women (mean age = 61.7), at 8 years postmenopause. CAC was analyzed as categories 0, 1 to 99, and ≥100. The mean CAC was 53 (range, 0 to 1,175), and 54% of the women had 0 scores. Large high-density lipoprotein (HDL) was inversely associated with CAC category, but small HDL was not. All very low-density lipoprotein (VLDL) subclasses—small, medium, and large—were positively associated with CAC (p <0.01). Small low-density lipoprotein (LDL) was positively associated with CAC (p <0.01), but medium and large LDL were not. Smaller LDL particle size (p <0.01) and higher levels of LDL particles (p <0.001) were associated with higher CAC category. In separate ordinal logistic regression models, small LDL, LDL particles, and large VLDL were each positively associated (p <0.05) with higher CAC after adjustment for age, systolic blood pressure (SBP), current smoking, and conventional measures of LDL cholesterol, HDL cholesterol, and triglycerides. These results suggest that the measurement of lipoprotein subclasses may improve the prediction of CAD in postmenopausal women beyond that provided by the conventional lipid panel and CAD risk factors.

Effects of atorvastatin on fasting and postprandial lipoprotein subclasses in coronary heart disease patients versus control subjects

The effects of atorvastatin at 20, 40, and 80 mg/day on plasma lipoprotein subclasses were examined in a randomized, placebo-controlled fashion over 24 weeks in 103 patients in the fasting state who had coronary heart disease (CHD) with low-density lipoprotein (LDL) cholesterol levels >130 mg/dl. The effects of placebo and atorvastatin 40 mg/day were examined in 88 subjects with CHD in the fasting state and 4 hours after a meal rich in saturated fat and cholesterol. These findings were compared with results in 88 age- and gender-matched control subjects. Treatment at the 20, 40, and 80 mg/day dose levels resulted in LDL cholesterol reductions of 38%, 46%, and 52% (all p <0.0001), triglyceride reductions of 22%, 26%, and 30% (all p <0.0001), and high-density lipoprotein (HDL) cholesterol increases of 6%, 5%, and 3%, respectively (all p <0.05 at the 20- and 40-mg doses). The lowest total cholesterol/HDL cholesterol ratio was observed with the 80 mg/day dose of atorvastatin (p <0.0001 vs placebo). Remnant-like particle (RLP) cholesterol decreased 33%, 34%, and 32%, respectively (all p <0.0001). Lipoprotein(a) [Lp(a)] cholesterol decreased 9%, 16%, and 21% (all p <0.0001), although Lp(a) mass increased 9%, 8%, and 10%, respectively (all p <0.01). In the fed state, atorvastatin 40 mg/day normalized direct LDL cholesterol (29% below controls), triglycerides (8% above controls), and RLP cholesterol (10% below controls), with similar reductions in the fasting state. At this same dose level, atorvastatin treatment resulted in 39%, 35%, and 59% decreases in fasting triglyceride in large, medium, and small very LDLs, as well as 45%, 33%, and 47% reductions in cholesterol in large, medium, and small LDL, respectively, as assessed by nuclear magnetic resonance (all significant, p <0.05), normalizing these particles versus controls (77 cases vs 77 controls). Moreover, cholesterol in large HDL was increased 37% (p <0.001) by this treatment. Our data indicate that atorvastatin treatment normalizes levels of all classes of triglyceride-rich lipoproteins and LDL in both the fasting and fed states in patients with CHD compared with control subjects.

S-nitrosothiols do not induce oxidative stress, contrary to other nitric oxide donors, in cultures of vascular endothelial or smooth muscle cells

Nitric oxide (NO) has been described to exert various anti-atherogenic actions. However, NO, in some cases, has been shown to stimulate the oxidation of low-density lipoprotein (LDL), which constitute an important triggering event in atherosclerosis. Thus, some NO donors, despite their advantages, might also induce oxidative stress. Therefore, the purpose of this study is to examine the effect of three different NO donors on LDL oxidation, in acellular system as well as in cultures of normal endothelial cells or smooth muscle cells, which constitute the two major cellular components of the arterial wall. Sodium nitroprusside oxidized strongly LDL in medium alone as well as in endothelial or smooth muscle cell cultures. Sydnonimine-1 (SIN-1) oxidized LDL already in the absence of cells and enhanced clearly the LDL oxidation in the cultures. S-nitroso- N-acetylpenicillamine was unable to oxidize LDL in synthetic medium alone as well as in the presence of cells, showing that the amount of superoxide and other reactive oxygen species released by these cells did not suffice, contrary to those liberated by macrophages, to combine to NO providing oxidant activity.

Cell-mediated oxidation of LDL: Comparison of different cell types of the atherosclerotic lesion

The three major cell types of the human atherosclerotic lesion — macrophages (Mø), smooth muscle cells (SMC) and endothelial cells (EC) — were compared for their ability to oxidise low density lipoprotein (LDL) in vitro under identical conditions. Near-confluent cultures were incubated for up to 48 h with 50 μg protein/ml LDL in Ham's F10 medium supplemented with 7 μM Fe2+. All three cell types oxidised LDL readily using our culture conditions. After 24 and 48 h, the degree of LDL oxidation was in the order: Mø > SMC > EC when based on cell growth area and EC > SMC > Mø when based on cellular DNA content. However, LDL oxidation in vitro progressed more slowly between 24 and 48 h, probably due to increasing toxicity to the cells and/or depletion of polyunsaturated fatty acids. We therefore compared the time of onset of LDL oxidation. The earliest increase in LDL oxidation was always apparent with SMC. Gas chromatography revealed that LDL oxidation by all three cell types followed a similar pattern. The polyunsaturated fatty acids linoleic acid (18:2) and arachidonic acid (20:4) were depleted (to 10.3–18.1% and 4.5–24.7% respectively, compared to native LDL), whereas the content of stearic acid (18:0) and oleic acid (18:1) remained unchanged. Cholesterol was depleted (to 54.1–75.6% of native LDL) with a concomitant rise in 7β-hydroxycholesterol (to 60.6–128.1 μg/mg LDL). This corresponds to a conversion of 4.9, 9.5 and 10.4% of LDL cholesterol in EC-, SMC- and Mø-modified LDL respectively. All three cell types showed significant toxicity in the oxidising culture after 24 h. The possible relevance to LDL oxidation in atherosclerosis is discussed.

Effects of individual and combined treatment with prostaglandins E2 and F2 alpha on progesterone secretion by ovine luteal cells supplemented with homologous serum lipoproteins in vitro.

Prostaglandin F2 alpha (PGF2 alpha) is a potent luteolysin, whereas prostaglandin E2 (PGE2) is generally luteotropic in vivo. To establish a model system for investigations of the mechanisms involved in these actions, we examined the effects of individual and combined treatment with PGE2 and PGF2 alpha on basal and ovine LH-stimulated progesterone secretion during long-term incubations conducted with and without supplemental homologous low-density lipoprotein (LDL) as substrate. Effects of both PGF2 and PGF2 alpha were concentration- and time-dependent and were further influenced by the presence of LDL and/or LH in medium. Neither of the prostaglandins exerted any significant effect before 48 h in culture, but distinctly different patterns of response to PGE2 and PGF2 alpha emerged thereafter. Low, but not high, concentrations of PGE2 increased progesterone secretion in the absence of LH, whereas PGF2 alpha (alone and in combination with PGE2) inhibited progesterone production in all medium formulations. The transcriptional inhibitor actinomycin effectively blocked the actions of PGF2 alpha, but had no effect on response to LH or PGE2. These data demonstrate that both the putative luteotropic actions of PGE2 and the potent, luteolytic effects of PGF2 alpha in vivo can be reproduced in long-term cultures of ovine luteal cells in vitro, and they suggest that the mechanism of PGF2 alpha-induced luteolysis may involve new protein synthesis.

Effects of high density lipoprotein subfractions on cholesterol homeostasis in human fibroblasts and arterial smooth muscle cells.

Ultracentrifugally isolated high density lipoprotein (HDL) particles of d greater than 1.125 g/ml promote net transport of cholesterol from cultured cells. Consequently, when cultured human fibroblasts and arterial smooth muscle cells were incubated with HDL3 (d = 1.125-1.21 g/ml) and "very high" density lipoprotein (VHDL, d = 1.21-1.25 g/ml), low density lipoprotein (LDL) receptor activity was induced and the rate of LDL degradation by the cells was increased. Enhancement of LDL degradation by HDL3 and VHDL was sustained over incubation periods of 5 days at medium LDL concentrations greater than needed to saturate the LDL receptors. Even during these long-term incubations with LDL, HDL3 and VHDL caused marked reductions in cellular cholesterol content. Thus, an increase in the rate of cholesterol transport from cells may lead to a steady-state decrease in cellular cholesterol content and a sustained increase in the rate of clearance of LDL from the extracellular fluid. In contrast to the effects of HDL3 and VHDL, the major subclasses of HDL2 (HDL2b, d = 1.063-1.100 g/ml; HDL2a, d = 1.100-1.125 g/ml) did not promote net cholesterol transport from cells. Moreover, by apparent direct blockage of the effects that HDL3 and VHDL had on cholesterol transport, HDL2 reversed the increased rate of LDL degradation induced by HDL3 and VHDL. These results suggest that the relative proportion of HDL subfractions in the extracellular fluid may be an important determinant of both the rate of cholesterol transport from cells and the rate of receptor-mediated catabolism of LDL.

Evidence for coordinate expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase ad low density lipoprotein binding activity.

A Chinese hamster ovary cell mutant that requires both cholesterol and unsaturated fatty acids for growth (Limanek, J. S., Chin, J., and Chang, T. Y. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 5452-5456) has been further characterized with respect to its dependence on cholesterol. Upon removal of serum lipids from the growth medium, the activity of the important cholesterogenic enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and the low density lipoprotein (LDL) binding activity both increase significantly in the normal cell. Both these increases were much less in the mutant cell. Studies in vitro with NaF indicate that the differences in reductase activities between normal and mutant cells are not due to differences in activation by a dephosphorylation mechanism. Heat inactivation profiles and Km for HMG-CoA of both cell reductases were found to be identical, thus reducing the possibility that the mutant cell contains a mutation in the polypeptide chain of reductase. The fact that in lipid-deficient medium both reductase and LDL binding activities are low in the mutant strongly suggests that the expression of these activities is controlled in a coordinate manner. This conclusion is supported by parallel studies on a spontaneous revertant of the mutant in which the expression of reductase and LDL binding activities have both reverted to normal. These results indicate that the phenotypic abnormalities seen in the mutant are probably caused by a single mutation. A common factor is postulated to mediate this coordinate expression, and the function of such a factor is altered in the mutant cell.

Biosynthesis of Low Density Lipoprotein by Cell-free Preparations of Rat Intestinal Mucosa

Abstract The capacity of cell-free preparations of rat small intestinal mucosa to synthesize and release lipoproteins was investigated. Palmitate-1-14C was administered intragastrically and 30 min later labeled cell-free fractions from homogenates of intestinal mucosa were prepared. The fractions (whole homogenate, mitochondria, and microsomes) were incubated in fortified media containing 3H-labeled amino acids, and lipoproteins of various densities were separated, after the addition of carrier rat plasma, by density centrifugation, by polyanion precipitation, and by immunoprecipitation. All fractions incorporated radioactivity into the lipid and protein moieties of the medium lipoproteins. The activity of the microsomal fraction accounted for most of the activity of the whole homogenate. Presence of postmicrosomal supernatant or pH 5 fraction, GTP, ATP, and ATP-generating system was essential for optimal activity of the microsomal fraction. The ratio of 14C:3H of microsomal (solubilized by LiCl) and medium low density lipoprotein (LDL) isolated by ultracentrifugation, by precipitation with polyanions, or by immunoprecipitation remained within reasonably narrow limits. The identity of microsomal and medium LDL with that of plasma LDL was demonstrated by immunoelectrophoresis, double immunodiffusion, and peptide mapping. The results indicate that the cellular equivalent of the microsomal fraction may be the major site of synthesis and association of the lipid and protein moieties of LDL. They further indicate that the intestinal mucosa may contribute significantly to the level of plasma LDL and that through the incorporation of LDL apoprotein into chylomicrons and very low density lipoprotein it can be of central importance in the transport of exogenous and endogenous lipid.