Influence of fitness status on very-low-density lipoprotein subfractions and lipoprotein(a) in men and women

Effects of portable pedal machines at work on lipoprotein subfraction profile in sedentary workers - the REMOVE study

BACKGROUND

Sedentary behaviour at work is a major cause of atherosclerosis, particularly in tertiary workers. However, no studies have ever assessed the effect of active workstation on lipoprotein subfraction profile. This study aimed to evaluate the effect of 12-week portable pedal machines (PPMs) on lipoprotein subfraction profile among healthy sedentary workers.

METHODS

Healthy administrative workers were randomized into an intervention group using PPMs for 12 weeks or a control group using normal-desk. Lipoprotein subfractions were assessed using Lipoprint® electrophoresis. Main outcomes were explored using mixed models with sensitivity analyses (four models).

RESULTS

We included 40 participants (43.7 ± 8.6 years old, 100% women, BMI 23.8 ± 3.4 kg/m2; sedentary time at work 7.7 ± 1.8 h/day). Groups did not differ at baseline in any outcomes. 32 participants finished the trial. Changes in lipoprotein subfractions were especially marked for LDL profile. There was an interaction time x group for all parameters related to LDL and their subfractions: total LDL-cholesterol (p = 0.012), LDL particle size (p = 0.027), large LDL subfractions 1 and 2 (p = 0.001), and small dense LDL subfractions 3 to 7 (p = 0.046), using the crude model. The interaction reflects difference in the direction of changes between groups. The LDL particle size significantly increased in the intervention group (from 271.9 ± 2.5 at t0 to 272.8 ± 1.9 Ångström at t1, p = 0.037) while it did not change in the control group (272.5 ± 1.7 at t0 to 271.8 ± 1.5Å at t1, p = 0.52). All interactions were constantly significant whatever the models. Influencing variables were mainly stress at work that was associated with an increase in total LDL-cholesterol (coefficient 3.15, 95CI 0.20 to 6.11 mg/dl, p = 0.038), and BMI that was associated with Large-LDL, Large-HDL, IDL-C and triglycerides.

CONCLUSIONS

Lipoprotein profile was improved after a 12-week PPMs intervention at work in healthy administrative workers. Changes were mainly showed for LDL and LDL subfractions. Lipoprotein profile was worsened by stress at work, BMI and age.

TRIAL REGISTRATION

NCT04153214.

Evolving targets for lipid-modifying therapy

The pathogenesis and progression of atherosclerosis are integrally connected to the concentration and function of lipoproteins in various classes. This review examines existing and emerging approaches to modify low-density lipoprotein and lipoprotein (a), triglyceride-rich lipoproteins, and high-density lipoproteins, emphasizing approaches that have progressed to clinical evaluation. Targeting of nuclear receptors and phospholipases is also discussed.

An elevated level of physical activity is associated with normal lipoprotein(a) levels in individuals from Maracaibo, Venezuela

Coronary artery disease is the main cause of death worldwide. Lipoprotein(a) [Lp(a)], is an independent risk factor for coronary artery disease in which concentrations are genetically regulated. Contradictory results have been published about physical activity influence on Lp(a) concentration. This research aimed to determine associations between different physical activity levels and Lp(a) concentration. A descriptive and cross-sectional study was made in 1340 randomly selected subjects (males = 598; females = 712) to whom a complete clinical history, the International Physical Activity Questionnaire, and Lp(a) level determination were made. Statistical analysis was carried out to assess qualitative variables relationship by chi2 and differences between means by one-way analysis of variance considering a P value <0.05 as statistically significant. Results are shown as absolute frequencies, percentages, and mean +/- standard deviation according to case. Physical activity levels were ordinal classified as follows: low activity with 24.3% (n = 318), moderate activity with 35.0% (n = 458), and high physical activity with 40.8% (n = 534). Lp(a) concentration in the studied sample was 26.28 +/- 12.64 (IC: 25.59-26.96) mg/dL. Lp(a) concentration according to low, moderate, and high physical activity levels were 29.22 +/- 13.74, 26.27 +/- 12.91, and 24.53 +/- 11.35 mg/dL, respectively, observing statistically significant differences between low and moderate level (P = 0.004) and low and high level (P < 0.001). A strong association (chi2 = 9.771; P = 0.002) was observed among a high physical activity level and a normal concentration of Lp(a) (less than 30 mg/dL). A lifestyle characterized by high physical activity is associated with normal Lp(a) levels.

Lipid metabolism response to a single, prolonged bout of endurance exercise in healthy young men

To discover the alterations in lipid metabolism linked to postexercise hypotriglyceridemia, we measured lipid kinetics, lipoprotein subclass distribution and lipid transfer enzymes in seven healthy, lean, young men the day after 2 h of cycling and rest. Compared with rest, exercise increased fatty acid rate of appearance and whole body fatty acid oxidation by approximately 65 and 40%, respectively (P < 0.05); exercise had no effect on VLDL-triglyceride (TG) secretion rate, increased VLDL-TG plasma clearance rate by 40 +/- 8%, and reduced VLDL-TG mean residence time by approximately 40 min and VLDL-apolipoprotein B-100 (apoB-100) secretion rate by 24 +/- 8% (all P < 0.05). Exercise also reduced the number of VLDL but almost doubled the number of IDL particles in plasma (P < 0.05). Muscle lipoprotein lipase content was not different after exercise and rest, but plasma lipoprotein lipase concentration increased by approximately 20% after exercise (P < 0.05). Plasma hepatic lipase and lecithin:cholesterol acyltransferase concentrations were not affected by exercise, whereas cholesterol ester transfer protein concentration was approximately 10% lower after exercise than after rest (P = 0.052). We conclude that 1) greater fatty acid availability after exercise does not stimulate VLDL-TG secretion, probably because of the increase in fatty acid oxidation and possibly also fatty acid use for restoration of tissue TG stores; 2) reduced secretion of VLDL-apoB-100 lowers plasma VLDL particle concentration; and 3) increased VLDL-TG plasma clearance maintains low plasma TG concentration but is not accompanied by similar increases in subsequent steps of the delipidation cascade. Acutely, therefore, the cardioprotective lowering of plasma TG and VLDL concentrations by exercise is counteracted by a proatherogenic increase in IDL concentration.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

Omega-3 fatty acids alter lipoprotein subfraction distributions and the in vitro conversion of very low density lipoproteins to low density lipoproteins

The purpose of this study was to determine the effects of a fish oil concentrate (FOC) on the in vitro conversion of very low density lipoproteins (VLDL) to intermediate (IDL) and low density lipoproteins (LDL). Six hypertriglyceridemic patients were randomly allocated to receive either placebo (olive oil) or FOC (1 g/14 kg body weight/day) for 4 weeks in a crossover study with a 4-week washout period. The FOC provided 3 g of eicosapentaenoic + docosahexaenoic acid per 70 kg of body weight, and it lowered plasma triglyceride and VLDL cholesterol levels by 35% and 42%, respectively. Decreases in the largest particles (VLDL(1)) were primarily responsible, with no effect noted in smaller VLDL particles (VLDL(2) and VLDL(3)). The FOC increased LDL cholesterol levels by 25% (P < 0.06) but did not affect LDL particle size. VLDL(1) and VLDL(3) were incubated in vitro with human postheparin lipases. Although triglycerides from both types of VLDL were hydrolyzed to the same extent with both treatments, particles isolated during the FOC phase were more readily converted into IDL and LDL than were control particles. These data suggest that the marine omega3 fatty acids may enhance the propensity of VLDL to be converted to LDL, partly explaining the decreased VLDL and increased LDL levels in FOC-treated patients.

Clinical application of genetic risk assessment strategies for coronary artery disease: genotypes, phenotypes, and family history

Individuals with genetic predisposition to atherosclerosis have an increased risk for developing coronary artery disease (CAD), especially at young ages. They may derive the greatest benefit from traditional preventive strategies and strategies targeting novel,emerging risk factors. Because CAD is a complex, multifactorial disorder, global risk assessment has been recognized as an effective approach in preventing CAD and its manifestations. The systematic collection and interpretation of family history information is currently the most appropriate screening approach to identify individuals with genetic susceptibility to CAD. Much of the familial aggregation of CAD might be explained by familial aggregation of established risk factors and emerging CAD risk factors. Tests to assess genetic risk for CAD are primarily biochemical analyses that measure the different pathways involved in development and progression of disease. Some of these can guide and explain responses to treatment.

Genetic evaluation for coronary artery disease

There is substantial evidence that genetic factors contribute to coronary artery disease (CAD). Currently, family history collection and interpretation is the best method for identifying individuals with genetic susceptibility to CAD. Family history reflects not only genetic susceptibility, but also interactions between genetic, environmental, cultural, and behavioral factors. Stratification of familial risk into different risk categories (e.g., average, moderate, or high) is possible by considering the number of relatives affected with CAD and their degree of relationship, the ages of CAD onset, the occurrence of associated conditions, and the gender of affected relatives. Familial risk stratification should improve standard CAD risk assessment methods and treatment guidelines (e.g., Framingham CAD risk prediction score and Adult Treatment Panel III guidelines). Individuals with an increased familial risk for CAD should be targeted for aggressive risk factor modification. Individuals with a high familial risk might also benefit from early detection strategies and biochemical and DNA-based testing, which can further refine risk for CAD. In addition, individuals with the highest familial risk might have mendelian disorders associated with a large magnitude of risk for premature CAD. In these cases, referral for genetic evaluation should be considered, including pedigree analysis, risk assessment, genetic counseling and education, discussion of available genetic tests, and recommendations for risk-appropriate screening and preventive interventions. Research is needed to assess the feasibility, clinical validity, clinical utility, and ethical, legal, and social issues of an approach that uses familial risk stratification and genetic evaluation to enhance CAD prevention efforts.

Effects of short-duration and long-duration exercise on lipoprotein(a)

PURPOSE

Most studies that use either a single exercise session, exercise training, or a cross-sectional design have failed to find a relationship between exercise and plasma lipoprotein(a) [Lp(a)] concentrations. However, a few studies investigating the effects of longer and/or more strenuous exercise have shown elevated Lp(a) concentrations, possibly as an acute-phase reactant to muscle damage. Based on the assumption that greater muscle damage would occur with exercise of longer duration, the purpose of the present study was to determine whether exercise of longer duration would increase Lp(a) concentration and creatine kinase (CK) activity more than exercise of shorter duration.

METHODS

Ten endurance-trained men (mean +/- SD: age, 27 +/- 6 yr; maximal oxygen consumption [VO(2max)], 57 +/- 7 mL x kg(-1) x min(-1)) completed two separate exercise sessions at 70% VO(2max). One session required 800 kcal of energy expenditure (60 +/- 6 min), and the other required 1500 kcal (112 +/- 12 min). Fasted blood samples were taken immediately before (0-pre), immediately after (0-post), 1 d after (1-post), and 2 d after (2-post) each exercise session.

RESULTS

CK activity increased after both exercise sessions (mean +/- SE; 800 kcal: 0-pre 55 +/- 11, 1-post 168 +/- 64 U x L(-1) x min(-1); 1500 kcal: 0-pre 51 +/- 5, 1-post 187 +/- 30, 2-post 123 +/- 19 U x L(-1) x min(-1); P < 0.05). However, median Lp(a) concentrations were not altered by either exercise session (800 kcal: 0-pre 5.0 mg x dL(-1), 0-post 3.2 mg x dL(-1), 1-post 4.0 mg x dL(-1), 2-post 3.4 mg x dL(-1); 1500 kcal: 0-pre 5.8 mg x dL(-1), 0-post 4.3 mg x dL(-1), 1-post 3.2 mg x dL(-1), 2-post 5.3 mg x dL(-1)). In addition, no relationship existed between exercise-induced changes in CK activity and Lp(a) concentration (800 kcal: r = -0.26; 1500 kcal: r = -0.02).

CONCLUSION

These results suggest that plasma Lp(a) concentration will not increase in response to minor exercise-induced muscle damage in endurance-trained runners.

Genetic predisposition to coronary artery disease

Understanding the genetic basis of coronary artery disease (CAD) can improve management and prevention. Family and twin studies, animal models and gene association studies support a genetic basis for CAD. Genes contribute to CAD development and progression, and response to risk factor modification and lifestyle choices. Family history is the best indicator of a predisposition to CAD and further refinement is possible with biochemical and DNA testing. Many inherited cardiovascular risk factors can be modified, such as LDL cholesterol, homocysteine and lipoprotein(a). Early detection of CAD might lead to earlier intervention for genetically susceptible individuals. However, data are lacking regarding the efficacy of this approach in preventing clinical events. Despite this lack of evidence, knowledge of genetic CAD susceptibility has value in providing risk information and guiding decision making. Further research that investigates outcomes regarding genetic risk assessment for CAD is necessary.

Strength training does not alter the effects of testosterone propionate injections on high-density lipoprotein cholesterol concentrations

The purpose of the study was to examine the long-term effects of a high-volume strength training program (vertical ladder climbing) and testosterone propionate injections (intraperitoneal) on serum lipid and lipoprotein concentrations in male Sprague-Dawley rats. The animals were randomly divided into a testosterone (T)-treated group (dose per injection, 2.5 mg/kg testosterone propionate solubilized in 1 mL safflower oil) and a control (C) group (injected with an isovolumic amount of safflower oil alone). Animals were further divided into a strength-trained group (E) and a sedentary group (S). The 10-week resistance training program consisted of weights (100% of body mass) appended to the tail as the animal climbed an 85-cm ladder to volitional fatigue. Following 10 weeks of strength training and testosterone injections, body weight was not significantly different between the main effects of strength training exercise (TE + CE v TS + CS) and testosterone injections (TE + TS v CE + CS) or between groups. Testicular mass (mean +/- SE) was measured as a relative indicator of testosterone effects. Both TE and TS had significantly reduced testicular mass (2.56 +/- 0.04 and 2.38 +/- 0.03 g, respectively) compared with CE and CS (3.49 +/- 0.03 and 3.49 +/- 0.04 g, respectively). No significant differences were observed between groups for total serum cholesterol, serum triglycerides, or serum low-density lipoprotein cholesterol (LDL-C). In contrast, significant decreases in high-density lipoprotein cholesterol (HDL-C) were observed for both TE (26.7 +/- 1.6 mg/dL) and TS (27.5 +/- 1.3 mg/dL) compared with CE (48.7 +/- 2.9 mg/dL) and CS (43.5 +/- 2.6 mg/dL). As a result, the total cholesterol to HDL-C ratio was significantly greater for TS + TE (4.7 +/- 0.1) compared with CS + CE (2.9 +/- 0.2). These observations suggest that in animals, a 10-week program of high-volume strength training does not elicit any beneficial effect on the lipid or lipoprotein status, nor does it attenuate the altered lipoprotein profile induced by testosterone propionate injections.

Diet and waist-to-hip ratio: important predictors of lipoprotein levels in sedentary and active young men with no evidence of cardiovascular disease

OBJECTIVE

Healthy, young men were studied to determine the relationship of energy and nutrient intake and physical activity to concentrations of plasma lipoprotein and cholesteryl ester transfer protein.

DESIGN

A cross-sectional study compared active and sedentary male subjects (17 to 35 years old) with no personal or family history of coronary heart disease. Participants kept 20-day food and activity journals. Individual intakes of energy, protein, carbohydrate, fat, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids, dietary fiber, and alcohol were evaluated. Measurements of blood lipids (total cholesterol and triglycerides, high- and low-density lipoprotein cholesterol); apolipoproteins; cholesteryl ester transfer protein; anthropometric variables (body mass index, waist-to-hip ratio, percentage of body fat); and aerobic capacity were taken during fall and spring data collection periods. SUBJECT SELECTION: Subjects were selected on the basis of normal blood lipid levels, absence of underlying disease, and willingness to comply with their current level of physical activity for the duration of the study. Minimal sample size for statistical power was 12 men per group: 12 of 15 subjects who exercised and 13 of 15 subjects who were sedentary completed all phases of the study.

STATISTICAL ANALYSES

Statistical analyses consisted of 2-way analysis of variance (activity level and season). Pearson product moment correlations and multiple regression analyses were conducted to assess whether energy and nutrient intakes, physical activity status, and/or anthropometric variables predicted plasma concentrations of lipids and apolipoproteins.

RESULTS

Lower waist-to-hip ratio, and not specifically activity level, was associated with higher levels of high-density lipoprotein cholesterol (HDL-C) and lower levels of low-density lipoprotein cholesterol (LDL-C). Dietary intake of saturated and monounsaturated fats and alcohol predicted changes in some apolipoprotein and lipoprotein levels.

APPLICATIONS

Use of waist-to-hip ratio in the primary prevention of coronary heart disease is a simple and cost-effective measure to predict development of abnormal lipoprotein profiles in young men. Specific dietary recommendations include adoption of a heart-healthy diet with emphasis on monounsaturated fatty acids (10% to 12% of energy or one third of total fat intake) and the suggestion that small amounts of alcohol (< 3 drinks per week) may, indeed, be beneficial. Because alcohol and waist-to-hip ratio were both important predictors of LDL-C level, even in active young men, the consumption of low levels of alcohol may be beneficial only if waist-to-hip ratio is maintained within the healthful range by achieving an appropriate balance of physical activity and macronutrient intake.

Potential new cardiovascular risk factors: left ventricular hypertrophy, homocysteine, lipoprotein(a), triglycerides, oxidative stress, and fibrinogen

The 1996 Bethesda Conference acknowledged left ventricular hypertrophy, hyperhomocysteinemia, lipoprotein(a) excess, hypertriglyceridemia, oxidative stress, and hyperfibrinogenemia as possible new cardiac risk factors. This review summarizes the current literature that supports these conditions as cardiac risk factors. Left ventricular hypertrophy is an independent risk factor for vascular disease. Improvement or progression of left ventricular hypertrophy influences subsequent cardiovascular complications. Clinical trials are under way to assess the potential benefit of decreasing homocysteine levels. The role of lipoprotein(a) excess in vascular disease is controversial. The atherogenic potential of lipoprotein(a) seems to be neutralized by effective reduction of low-density lipoprotein cholesterol levels. Increasing evidence supports an independent role of hypertriglyceridemia in cardiovascular disease and a possible clinical benefit from decreasing triglyceride levels. Among antioxidant micronutrients, supplementation with vitamin E has been shown to be beneficial in primary and secondary prevention studies. Data supporting the use of other antioxidants are much weaker. Preliminary evidence suggests that reducing fibrinogen levels in patients with high baseline levels and coronary disease may be beneficial. Despite the potential relation between new risk factors and cardiovascular disease, routine clinical application of these conditions as cardiovascular risk factors would be premature. Evidence is needed that these conditions extend prognostic ability beyond conventional risk factors and that modification of these conditions can reduce the risk for cardiovascular events.

The relation between bone mineral density, insulin-like growth factor I, lipoprotein (a), body composition, and muscle strength in adolescent males

Osteoporosis is the most common metabolic bone disease. A low peak bone mass is regarded a risk factor for osteoporosis. Heredity, physical activity, and nutrition are regarded important measures for the observed variance in peak bone mass. Lp(a) lipoprotein is a well-known risk factor for atherosclerosis. Serum insulin-like growth factor I (IGF-I) has been found to be increased in males with early cardiovascular disease. In this study, we evaluated the association between bone mass, body constitution, muscle strength, Lp(a), and IGF-I in 47 Caucasian male adolescents (mean age, 16.9 yr). Bone mineral density (BMD) and body composition were measured by dual x-ray absorptiometry, muscle strength of thigh using an isokinetic dynamometer, IGF-I by RIA, and Lp(a) by enzyme-linked immunosorbent assay. IGF-I was only associated with Lp(a) (r = 0.38, P < 0.01). Lp(a) was related to total body (r = 0.40, P < 0.01), skull (r = 0.45, P < 0.01), and femoral neck BMD (r = 0.44, P < 0.01). Lp(a) was also related to fat mass (r = 0.34, P < 0.05) and muscle strength (r = 0.30-0.42, P < 0.05). After multiple regression and principal component (PC) analysis, the so-called PC body size (weight, fat mass, lean body mass, and muscle strength) was the most significant predictor of BMD (beta = 0.28-0.51, P < 0.05-0.01), followed by the so-called PC physical activity (beta = 0.28-0.38, P < 0.05-0.01, weight-bearing locations). However, the PC analysis confirmed that Lp(a) was an independent predictor of total body, skull, and femoral neck BMD (beta = 0.33-0.36, P < 0.01). The present investigation confirms that BMD, body size, and muscle strength are closely related and that the level of physical activity is a major determinant of BMD. However, the positive relation of Lp(a), a major risk factor for cardiovascular disease, to BMD has not previously been described. The importance of this observation has to be further investigated.

HDL-cholesterol reductions associated with adult growth hormone replacement

OBJECTIVE

To study the effects of human growth hormone (hGH) replacement on serum lipids and lipoprotein (a) (Lp(a)) concentrations.

DESIGN

A randomized double blind placebo controlled trial for 6 months followed by an open trial where all patients were treated with hGH for a further 6 months. Treatment was with recombinant hGH given in a dose of 0.125U/kg/wk increasing to 0.25U/Kg/wk.

PATIENTS

Thirty two patients with growth hormone deficiency were recruited, but two withdrew because of side effects. Of the thirty patients (age 35.1 +/- 11.8 year; mean +/- SD) completing the study 13 of were assigned to the placebo group for six months and 17 to active treatment from the start.

MEASUREMENTS

Fasting serum samples were analysed for total cholesterol, High density lipoprotein (HDL)-cholesterol, HDL-subfractions, triglycerides, lipoprotein (a) (Lp(a)) and IGF-1. LDL-cholesterol was calculated using the Friedewald formula.

RESULTS

Compared to placebo, 6 months treatment with hGH therapy resulted in increased IGF-1 (37.6 +/- 4.1 vs. 14.0 +/- 2.2 nmol/l, P < 0.01), but there was no significant difference in any of the lipid parameters measured between placebo and active treatment groups at 6 months. hGH was associated with a decrease in HDL-cholesterol concentration from baseline to 6 months (0.97 +/- 0.08 to 0.76 +/- 0.10 mmol/l P < 0.01), especially within the HDL2 subfraction. This reduction was maintained at 12 months. There was no change in Lp(a) concentrations from 0 to 6 months (placebo -26 (-340 to 82), median and range, active -4 (-586 to 212) mg/l). There was no change in total cholesterol, LDL-cholesterol, triglycerides or proportion of HDL subfractions.

CONCLUSIONS

Treatment with hGH can reduce serum HDL-cholesterol concentrations. Further investigation of this is required.