Multifactorial treatment of hypertensive men at high cardiovascular risk and low-density lipoprotein cholesterol affinity to human arterial proteoglycans

Overfeeding Saturated Fat Increases LDL (Low-Density Lipoprotein) Aggregation Susceptibility While Overfeeding Unsaturated Fat Decreases Proteoglycan-Binding of Lipoproteins

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Objective:

We recently showed that measurement of the susceptibility of LDL (low-density lipoprotein) to aggregation is an independent predictor of cardiovascular events. We now wished to compare effects of overfeeding different dietary macronutrients on LDL aggregation, proteoglycan-binding of plasma lipoproteins, and on the concentration of oxidized LDL in plasma, 3 in vitro parameters consistent with increased atherogenicity.

Approach and Results:

The participants (36 subjects; age, 48±10 years; body mass index, 30.9±6.2 kg/m²) were randomized to consume an extra 1000 kcal/day of either unsaturated fat, saturated fat, or simple sugars (CARB) for 3 weeks. We measured plasma proatherogenic properties (susceptibility of LDL to aggregation, proteoglycan-binding, oxidized LDL) and concentrations and composition of plasma lipoproteins using nuclear magnetic resonance spectroscopy, and in LDL using liquid chromatography mass spectrometry, before and after the overfeeding diets. LDL aggregation increased in the saturated fat but not the other groups. This change was associated with increased sphingolipid and saturated triacylglycerols in LDL and in plasma and reduction of clusterin on LDL particles. Proteoglycan binding of plasma lipoproteins decreased in the unsaturated fat group relative to the baseline diet. Lipoprotein properties remained unchanged in the CARB group.

Conclusions:

The type of fat during 3 weeks of overfeeding is an important determinant of the characteristics and functional properties of plasma lipoproteins in humans.

Registration:

URL: http://www.clinicaltrials.gov; Unique identifier NCT02133144.

ApoB-100 Lipoprotein Complex Formation with Intima Proteoglycans as a Cause of Atherosclerosis and Its Possible Ex Vivo Evaluation as a Disease Biomarker

Experimental and clinical data indicate that the initiation and progress of atherosclerosis and its clinical manifestations are first caused by circulating apoB-100 lipoproteins that enter and are retained in the arterial intima. Extracellular sulfated proteoglycans (PGs) of the intima are the retention agents. The PGs also initiate physical and biochemical lipoprotein degradation with the production of bioactive, lipid products that trigger an inflammatory response that leads to atherosclerosis. There are many simple methods for measuring abnormalities of circulating lipoproteins and their relation to atherosclerotic cardiovascular disease (ACVD). However, limited research aims to evaluate procedures that could report quantitatively about the contribution of the interaction of apoB-100 lipoprotein-arterial intima PGs to clinical manifestation of ACVD. In the present review we discuss observations indicating that simple ex vivo evaluation of the affinity of apoB-100 lipoproteins for arterial PGs and glycosaminoglycans (GAGs) can give an indication of its association with clinical manifestations of atherosclerosis. In addition, we discuss molecular and cellular aspects of the apoB-100 lipoproteins association with arterial PGs that are related to atherogenesis and that support the experimental framework behind the current “Response-to-Retention” hypothesis of atherosclerosis.

Obesity in older adults: a systematic review of the evidence for diagnosis and treatment

OBJECTIVE

Although obesity is increasing in older U.S. adults, treatment is controversial in this age group. We sought to examine evidence concerning obesity's health-related risks, diagnostic methods, and treatment outcomes in older individuals.

RESEARCH METHODS AND PROCEDURES

We searched MEDLINE and Cochrane Library databases, consulted with experts, and examined bibliographies for English language studies discussing obesity in older adults (mean age > or = 60), published between January 1980 and November 2005. Inclusion criteria were met by 32 longitudinal analyses, seven diagnostic studies, and 17 randomized controlled trial articles. At least two authors independently reviewed and abstracted study design, population, results, and quality information.

RESULTS

Correlations between body fat and three anthropometric measures (BMI, waist circumference, waist-to-hip ratio) decrease with age but remain clinically significant. Obesity contributes to risk for several cardiovascular endpoints, some cancers, and impaired mobility but protects against hip fracture. The association between obesity and mortality declines as age increases. Intensive counseling strategies incorporating behavioral, dietary, and exercise components promote a weight loss of 3 to 4 kg over 1 to 3.3 years. The loss is linked with improved glucose tolerance, improved physical functioning, reduced incidence of diabetes and a combined hypertension and cardiovascular endpoint, and reduced bone density.

DISCUSSION

In older adults, obesity can be diagnosed with standard clinical measures. Intensive counseling can promote modest sustained weight loss, but data are insufficient to evaluate surgical or pharmacological options. Obesity treatment is most likely to benefit individuals with high cardiovascular risk. Limited data suggest possible functional improvement. Treatment should incorporate measures to avoid bone loss.

Multiple risk factor intervention reduces cardiovascular risk in hypertensive patients with echolucent plaques in the carotid artery

OBJECTIVE

In a previously published randomized 6-year study we observed that multiple risk factor intervention reduced cardiovascular risk in high-risk hypertensive men, and that this effect was confined to patients with carotid artery plaques. Hypothetically, the underlying mechanism might have been a stabilization of echolucent, instable, rupture-prone plaques. The aim of the present study was to examine plaque characteristics by B-mode ultrasound in the previous intervention study, and also to investigate the relationship between plaque characteristics at baseline and cardiovascular events during the 6-year follow-up in the two randomization groups.

METHODS

High resolution B-mode ultrasound was used to characterize plaque echogenicity in four subgroups - dominantly echolucent, substantially echolucent, dominantly echogenic, and uniformly echogenic.

RESULTS

In the usual care group 17 of 32 (53%) patients with echolucent plaques at baseline suffered from a combined end-point (any death or nonfatal myocardial infarction or nonfatal stroke) during follow-up compared with seven of 28 (25%) patients in the intervention group (P = 0.036). The corresponding numbers in patients with echogenic plaques were n = 4/13 (31%) and n = 4/17 (24%), respectively (NS). In the usual care group 11 of 33 (33%) patients with no plaques suffered from a combined end-point during follow-up compared with 11 of 30 (37%) in the intervention group.

CONCLUSION

Our data indicate that the beneficial effect of the multiple risk intervention programme was confined to those patients with echolucent plaques. The data have to be confirmed with a large-scale trial.

Multiple risk intervention trial in high risk hypertensive men: comparison of ultrasound intima-media thickness and clinical outcome during 6 years of follow-up

OBJECTIVES

The objective was to analyse whether a favourable change in risk factors, caused by a comprehensive risk factor modification programme, affected intima-media thickness (IMT) in the common carotid artery, and whether any such change was associated with a change in cardiovascular events during a 6-year follow-up.

DESIGN

Patients were randomized 1 : 1 to special intervention or usual care.

SETTING

Hypertension Unit at university hospital.

SUBJECTS

A total of 164 patients were randomized. Inclusion criteria were male, aged 50-72 years (at randomization) and one or more of the following: Serum cholesterol level > 6.5 mmol L(-1), smoking or diabetes mellitus. All patients were prescribed antihypertensive treatment since many years. In 142 men good quality ultrasound recording of the common carotid IMT were achieved at baseline, 119 were re-examined after 3.3 years, and 97 patients were available for examination after mean follow-up time of 6.2 years. Cardiovascular events were available for all randomized patients.

INTERVENTIONS

The nonpharmacological special intervention programme was based on one information meeting followed by five weekly 2-h sessions with participation of patients and spouses. The diet recommendations were similar to established guidelines. Overweight patients were instructed to lose weight, and diabetic patients were systematically taught self-monitoring of blood glucose. Smokers were invited to a smoking cessation programme with five weekly meetings. Follow-up visits were thereafter scheduled every 6 months. Lipid lowering drugs were recommended in the intervention group if the treatment goals using nonpharmacological measures were not achieved. Patients in the usual care group were told to quit smoking and to lower their consumption of fat and glucose. Antihypertensive treatment (i.e., selection of drugs) was on purpose kept similar in the two groups.

MAIN OUTCOME MEASURES

The IMT of the common carotid artery as measured by ultrasound. Cardiovascular events during follow-up.

RESULTS

Significant net reductions were seen for serum cholesterol, triglycerides, fasting glucose and smoking. No difference in change in IMT was observed during follow-up between the two randomization groups. The explanation was that patients with positive plaque status at baseline had a much larger increase in IMT over time than patients with negative plaque status, and that patients with positive plaque status more often survived and were available for re-examination after 6 years in the intervention group than in the usual care group. Total mortality was lower in the intervention group, compared with the usual care group, 13 and 29%, respectively (P=0.028).

CONCLUSIONS

In high risk populations, long-term studies with surrogate endpoints may be misleading because of missing data in patients where a large increase in IMT would have been observed, had they been re-examined. Another important conclusion from our study was that the gloomy prognosis for this patient category may be improved by a dedicated risk factor intervention programme. The improved prognosis was observed mainly in those patients at highest risk judged from history of cardiovascular disease or positive ultrasound plaque status at baseline.

Dietary advice given by a dietitian versus other health professional or self-help resources to reduce blood cholesterol

BACKGROUND

The average level of blood cholesterol is an important determinant of the risk of coronary heart disease. Blood cholesterol can be reduced by dietary means. Although dietitians are trained to provide dietary advice, for practical reasons it is also given by other health professionals and occasionally through the use of self-help resources.

OBJECTIVES

To assess the effects of dietary advice given by a dietitian compared with another health professional, or the use of self-help resources, in reducing blood cholesterol in adults.

SEARCH STRATEGY

We searched The Cochrane Library (to Issue 2 1999), MEDLINE (1966 to January 1999), EMBASE (1980 to December 1998), Cinahl (1982 to December 1998), Human Nutrition (1991 to 1998), Science Citation Index, Social Sciences Citation Index, hand searched conference proceedings on nutrition and heart disease, and contacted experts in the field.

SELECTION CRITERIA

Randomised trials of dietary advice given by a dietitian compared with another health professional or self-help resources. The main outcome was difference in blood cholesterol between dietitian groups compared with other intervention groups.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Eleven studies with 12 comparisons were included, involving 704 people receiving advice from dietitians, 486 from other health professionals and 551 people using self-help leaflets. Four studies compared dietitian with doctor, seven with self-help resources, and one compared dietitian with nurse. Participants receiving advice from dietitians experienced a greater reduction in blood cholesterol than those receiving advice only from doctors (-0.25 mmol/L (95% CI -0.37, -0.12 mmol/L)). There was no statistically significant difference in change in blood cholesterol between dietitians and self-help resources (-0.10 mmol/L (95% CI -0.22, 0.03 mmol/L)). No statistically significant differences were detected for secondary outcome measures between any of the comparisons with the exception of dietitian versus nurse for HDLc, where the dietitian groups showed a greater reduction (-0.06 mmol/L (95% CI -0.11, -0.01)). No significant heterogeneity between the studies was detected.

REVIEWER'S CONCLUSIONS

Dietitians were better than doctors at lowering blood cholesterol in the short to medium term, but there was no evidence that they were better than self-help resources. The results should be interpreted with caution as the studies were not of good quality and the analysis was based on a limited number of trials. More evidence is required to assess whether change can be maintained in the longer term. There was no evidence that dietitians provided better outcomes than nurses.

Association of apo B lipoproteins with arterial proteoglycans: pathological significance and molecular basis

Retention of apo B-100 lipoproteins, low density lipoprotein (LDL) and probably lipoprotein(a), Lp(a), by intima proteoglycans (PGs) appears to increase the residence time needed for their structural, hydrolytic and oxidative modifications. If the rate of LDL entry exceeds the tissue capacity to eliminate the modified products, this process may be a contributor to atherogenesis and lesion advancement. LDL binds to PGs of the intima, by association of specific positive segments of the apo B-100 with the negatively-charged glycosaminoglycans (GAGs) made of chondroitin sulfate (CS), dermatan sulfate (DS) and probably heparan sulfate (HS). Small, dense LDL has a higher affinity for CS-PGs than large buoyant particles, probably because they expose more of the segments binding the GAGs than larger LDL. PGs cause irreversible structural alterations of LDL that potentiate hydrolytic and oxidative modifications. These alterations also increase LDL uptake by macrophages and smooth muscle cells. These in vitro data suggest that part of the atherogenicity of LDL may depend on its tendency to form complexes with arterial PGs in vivo. Ex vivo results support this hypothesis. Subjects with coronary heart disease have LDL with significantly higher affinity for arterial PGs. This is also a characteristic of subjects with the atherogenic lipoprotein phenotype, with high levels of small, dense LDL. The LDL-PG affinity, however can be modified by dietary or pharmacological interventions that change the composition and size of LDL. Lesion-prone intima contain PGs with a high affinity for LDL. Increased LDL entrapment at these sites may be a key step in a cyclic atherogenic process.

Cellular consequences of the association of apoB lipoproteins with proteoglycans. Potential contribution to atherogenesis

Many of the discussed results come from empirical experiments performed with in vitro models whose relevance to the complex environment of the intima is limited. However, they are consistent with the line of reasoning that intima PGs interact specifically with apoB lipoproteins and contribute to their retention. This could provide the residence time and the initial alterations of the lipoproteins that favor their further modifications by oxidative processes and hydrolytic enzymes. Products of such modifications, and the modified particles, may be stimuli for changes in the functionality of endothelium, smooth muscle cells, and macrophages. The focal synthesis of PGs with high affinity for apoB lipoproteins could make the phenomena chronic. Clinical and laboratory studies indicate that dense LDL, poor in surface polar lipids, is associated with an atherogenic phenotype. Particles with these properties may contribute to the disease via its high affinity for arterial PGs. This affinity can be modulated by diet, lifestyle, and lipid-lowering drugs.