Lipoprotein response to exercise training and a low-fat diet in older subjects with glucose intolerance

miR548ai antagonism attenuates exosome-induced endothelial cell dysfunction

Endothelial cell (EC) and smooth muscle cell (SMC) are major cell types adjacent in the vascular wall. Recent progress indicates that their communication is crucial for vascular homeostasis and pathogenesis. In particular, dysfunctional (proliferative) SMCs through exosomes can induce EC dysfunction (impaired growth). The current study suggests that miR548ai, a rarely known microRNA, may provide a molecular target for protection against SMC/exosome-induced EC dysfunction. We performed microarray profiling of microRNAs of dysfunctional human primary aortic SMCs induced by different cytokines (PDGF-BB, TGFβ1, TNFα, IL1β). Among the microRNAs commonly upregulated by these cytokines, miR548ai showed the most robust changes, as also validated through quantitative PCR. This cytokine-induced miR548ai upregulation was recapitulated in the qPCR determination of SMC-derived exosomal microRNAs. Consistent with SMC-to-EC communication, the exosomes extracted from cytokine-stimulated SMCs impaired human EC proliferation and migration. Of particular interest, this SMC exosomal impingement on ECs was countered by transfection of miR548ai inhibitor microRNA into ECs. Furthermore, the miR548ai inhibitor transfected into SMCs attenuated SMC dysfunction/proliferation. Thus, these results identify miR548ai as a novel target; namely, miR548ai inhibitor mitigates EC dysfunction induced by exosomes derived from dysfunctional SMCs. This new knowledge may aid the future development of microRNA-based treatment of vascular disorders.

Effect of α-lipoic acid and exercise training on cardiovascular disease risk in obesity with impaired glucose tolerance

Obese subjects with impaired glucose tolerance (IGT) are more susceptible than healthy individuals to oxidative stress and cardiovascular disease. This randomised controlled investigation was designed to test the hypothesis that α-lipoic acid supplementation and exercise training may elicit favourable clinical changes in obese subjects with IGT. All data were collected from 24 obese (BMI ≥ 30 kg/m²) IGT patients. Following participant randomisation into two groups, fasting venous blood samples were obtained at baseline, and before and following intervention. The first group consisted of 12 participants who completed a 12 week control phase followed by 12 weeks of chronic exercise at 65% HR_max for 30 minutes a day, 5 days per week, while ingesting 1 gram per day of α-lipoic acid for 12 weeks. The second group consisted of 12 participants who completed the same 12 week control phase, but this was followed by 12 weeks of 1 gram per day of α-lipoic acid supplementation only (no exercise). The main findings show a comparatively greater rate of low density lipoprotein (LDL) oxidation in the group consisting of α-lipoic acid only (p < 0.05 vs. pre intervention), although total oxidant status was lower post intervention (p < 0.05 vs. baseline) in this group. However, exercise and α-lipoic acid in combination attenuates LDL oxidation. Furthermore, in the α-lipoic acid supplement plus exercise training group, total antioxidant capacity was significantly increased (p < 0.05 vs. baseline and pre intervention). Body fat percentage and waist and hip circumference decreased following exercise training (p < 0.05 vs. post intervention). There were no selective treatment differences for a range of other clinical outcomes including glycaemic regulation (p > 0.05). These findings report that α-lipoic acid ingestion may increase the atherogenicity of LDL when ingested in isolation of exercise, suggesting that in IGT the use of this antioxidant treatment does not ameliorate metabolic disturbances, but instead may detrimentally contribute to the pathogenesis of atherosclerosis and development of CVD. However, when α-lipoic acid is combined with exercise, this atherogenic effect is abolished.

Response of Blood Lipids to Physical Exercise in Elderly Subjects

Regular physical activity plays an important role in nonpharmacologic management of hyperlipidemia, in both the primary and secondary prevention of coronary heart disease. Training intensity and duration, health status (especially the presence of cardiovascular disease), and concomitant changes in body mass and dietary habits are the most important factors that can modify the physical activity-blood lipid profile relationship in the elderly. The benefit of regular exercise goes beyond direct influence on blood lipids; it aids in reducing weight, decreasing fat mass, increasing lean body mass, reducing elevated blood pressure, and increasing insulin sensitivity. Regular physical activity has become widely recommended as an important element of healthy and successful aging and should be encouraged in individuals without contraindications. (c)2001 CHF, Inc.

Dose-response: variation with age, sex, and health status

PURPOSE

The purpose of this study was to summarize the literature on the influence of age, sex, and health status on the changes in systolic (SBP) and diastolic blood pressure (DBP), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) consequent to exercise training.

METHODS

A MEDLINE search was performed from January 1966 through August 2000 to identify studies that have investigated the effects of age, sex, and health status on the changes in the outcome variables with exercise training. References from these studies and from review and meta-analysis studies were also reviewed.

RESULTS AND CONCLUSIONS

The results indicate that age has little or no influence on the changes in SBP, DBP, TG, and HDL-C in response to exercise training. When looking at sex, females appear to have an attenuated response to exercise training compared with males with respect to SBP, DBP, and HDL-C, but the data for TG are equivocal. Finally, there appears to be more favorable changes in resting SBP and DBP, TG, and HDL-C in unhealthy subjects (hypertensive and post-MI patients) when compared with healthy subjects.

Combined dietary and exercise intervention for control of serum cholesterol in the workplace

PURPOSE

To elucidate a potential combined dietary and exercise intervention affect on cardiovascular risk reduction of the National Aeronautics and Space Administration Headquarters employees.

DESIGN

A nonexperimental, longitudinal, clinical-chart review study (1987 to 1996) of an identified intervention group and a reference (not a control) group.

SETTING

The study group worked in an office environment and participated in the annual medical examinations.

SUBJECTS

An intervention group of 858 people with initially elevated serum cholesterol, and a reference group of 963 people randomly sampled from 10% of the study group.

MEASURES

Serum cholesterol data were obtained for both groups, respectively, from pre- and postintervention and annual examinations. The reference group was adjusted by statistical exclusion of potential intervention participants. Regression equations (cholesterol vs. study years) for the unadjusted/adjusted reference groups were tested for statistical significance.

INTERVENTION

An 8-week individualized, combined dietary and exercise program was instituted with annual follow-ups and was repeated where warranted.

RESULTS

Only the unadjusted (but not the adjusted) reference group with initial mean total serum cholesterol levels above 200 mg/dL shows a significant 9-year decline trend and significant beta coefficient tests. An intervention effect is suggested. Mean high density lipoprotein cholesterol rose slightly in the intervention group but was maintained in the reference group.

CONCLUSION

With potential design limitations, the NASA intervention program focusing on a high risk group may be associated to some degree, if not fully, with an overall cardiovascular risk profile improvement.

Sequential effects of aerobic exercise training and weight loss on risk factors for coronary disease in healthy, obese middle-aged and older men

The relative benefits of weight loss (WL) versus aerobic exercise training (AEX) on cardiac risk factors in obese individuals remain controversial. In this study, we examined the effects of the sequential interventions of 9 months of AEX followed by weight loss with continued AEX (AEX + WL) on cardiac risk factors in 21 obese (body fat, 29.5% +/- 0.8%, mean +/- SEM) middle-aged and older men. AEX increased the maximal aerobic capacity ([VO2max] in liters per minute) of these men by 14% (P < .001), with no significant change in weight. AEX did not improve blood pressure (BP) or oral glucose tolerance, and had no significant effect on lipid concentrations. During the AEX + WL intervention, the 21 men lost 8.1 +/- 0.6 kg. Despite continued training, there was no further increase in VO2max during this intervention. Compared with AEX, AEX + WL decreased glucose and insulin responses during the oral glucose tolerance test (OGTT) by 8% (P < .05) and 30% (P < .01), respectively. AEX + WL reduced plasma triglyceride (TG) by 17% (P < .05) and low-density lipoprotein cholesterol (LDL-C) by 8% (P < .01) and increased high-density lipoprotein cholesterol (HDL-C) by 11% (3.7 mg/dL, P < .01). The sequential interventions resulted in a 20% decrease in the LDL-C/HDL-C ratio. The results demonstrate that AEX + WL had a more substantial impact than AEX alone on glucose tolerance and lipoprotein concentrations. Physicians should encourage obese patients to become physically active and lose weight to improve their cardiac risk factor profile.

Treatment of childhood syndrome X

OBJECTIVE

Hyperinsulinemia, hyperlipidemia, hypertension, and coronary artery disease comprise a quartet known as Syndrome X. This syndrome was first described in adults, but has recently been described in children and adolescents. The purpose of our study was to determine if diet or exercise is able to change the clinical profile of Syndrome X in children.

STUDY DESIGN

We recruited 36 obese (% ideal body weight = 170.3 +/- 31.1), children (9 to 12 yrs old) known to have high fasting cholesterol levels (177.5 +/- 33.5 mg/dL). Each participated in a 6-week protocol in one of three groups: control (C), diet (D), or exercise (E). Twenty-five of the patients completed the study with full compliance. At the beginning and end of the study, we measured weight, height, blood pressure, serum insulin, and a lipid profile including: cholesterol, low density lipoprotein, high density lipoprotein (HDL), triglycerides, and apolipoprotein A (ApoA). All subject groups were similar before the study. The D group had the greatest attrition (40%) and all of the E group completed the study.

RESULTS

After the 6-week study period, there was no significant weight loss or change in body mass index for any group. There was no significant change in blood pressure and there was no significant decline of fasting cholesterol or low density lipoprotein levels in any of the groups. HDL levels were low in all groups and did not significantly change with treatment. There was a significant decline in the triglyceride levels in both the diet and exercise groups after the study (preD = 150 +/- 60; postD = 122 +/- 50; preE = 165 +/- 50; postE = 116 +/- 39). Both the D and E groups also demonstrated a significant decrease in ApoA levels (preD = 174 +/- 33; postD = 142 +/- 24; preE = 200 +/- 50; postE = 161 +/- 23). Most impressively, fasting insulin levels significantly decreased with both diet and exercise, but did not change in controls during the 6 weeks (preC = 52 +/- 19; postC = 53 +/- 21; preD = 54 +/- 23; postD = 15 +/- 8; preE = 48 +/- 21; postE = 9).

CONCLUSIONS

The findings of this study are consistent with previous studies describing the presence of Syndrome X in childhood. Both diet and exercise were effective in lowering triglyceride, ApoA levels, and insulin levels. However, due to the large rate of noncompliance in the diet group, exercise seems to be the best treatment for improvement in Syndrome X in children.

Exercise as treatment for obesity

In recent times, affluent societies have become less physically active, and this has undoubtedly contributed to the increased incidence of obesity. Formal programs of exercise training can reduce body weight and fat, but, in many cases, the changes produced by exercise are small. When combined with energy restriction, exercise results in little further weight loss, but there is a strong trend for a greater loss of body fat. Thus, during diet-induced weight loss, added exercise seems to accelerate fat loss and maintain lean body mass, a condition which may prevent a decline in RMR. It is becoming increasingly clear that weight loss is better maintained when exercise is part of a weight-reducing program. Furthermore, following a period of diet-induced weight loss, participation in regular exercise amounting to an energy expenditure of more than 1500 kcal/week will result in more successful maintenance of the lesser weight. An emphasis should be placed on adopting life-long habits conducive to weight control and overall health rather than temporary measures for weight loss. A program which encompasses regular physical activity, modest energy intake, and reduced calories from fat has the potential to meet such a goal. Regular physical activity has the potential to reverse insulin resistance, improve cardiovascular function and the blood lipid profile, and control high blood pressure. Overweight individuals can obtain these important benefits even if body weight is not completely normalized during a program of regular physical activity. This should help alleviate problems of diabetes, heart disease, and hypertension often associated with being overweight. Further research is needed to identify more specifically the optimal amount, type, and intensity of exercise needed to produce weight loss or maintain ideal body weight. To date, the best recommendation comes from the American College of Sports Medicine. Persons are urged to engage in regular physical activity which promotes a daily energy expenditure of at least 300 kcal/day and to choose from a variety of activities, in particular, those which are enjoyable and that can be continued for life.

Use of the Food Guide Pyramid and US Dietary Guidelines to improve dietary intake and reduce cardiovascular risk in active-duty Air Force members

OBJECTIVE

To determine whether adoption of dietary patterns consistent with the US Dietary Guidelines for Americans and the Food Guide Pyramid, combined with exercise training, result in significant reductions in cardiovascular risk compared with a regimen of exercise therapy alone.

DESIGN

A randomized trial to compare the effects of exercise alone (n = 17) with the effects of exercise and dietary intervention (n = 15).

SETTING

McClellan Air Force Base medical clinic (Sacramento, Calif).

SUBJECTS

Thirty-two members of the Air Force (20 men and 12 women) were recruited at the time they entered a 90-day fitness improvement program. Mean age was 32 years.

INTERVENTION

All subjects participated in a 90-day fitness program. Half of the group received individualized dietary counseling using the Food Guide Pyramid as a primary educational tool.

MAIN OUTCOME MEASURES

Changes in body mass index, plasma lipids and lipoprotein levels, aerobic capacity, and dietary intake were selected to evaluate the effectiveness of the intervention.

STATISTICAL ANALYSES PERFORMED

Outcome measures were evaluated by analysis of variance. A paired t test was performed to compare changes in food-group servings and food-group fat intake from baseline values for the exercise-plus-diet group.

RESULTS

Percentage of energy from fat decreased from 39% to 23% for the exercise-plus-diet group, and servings from each of the food groups changed to reflect current guidelines. This group also had significant reductions in body mass index, total cholesterol level, and low-density lipoprotein level: 2% (P = .0001), 9% (P = .003), and 13% (P = .005), respectively. No change was observed for the exercise-only group. Additionally, a significant improvement in maximum oxygen consumption (P = .01) of 38% (vs 14% for the control group) was achieved.

CONCLUSIONS

Dietary modification in accordance with the Food Guide Pyramid and the US Dietary Guidelines results in significant reductions in known cardiovascular risk factors and improves the response to exercise training.