Low-density lipoprotein particle size, triglyceride-rich lipoproteins, and glucose tolerance in non-diabetic men with essential hypertension

Associations between the lipid profile and the development of hypertension in young individuals - the preliminary study

INTRODUCTION

Hypertension is the leading direct cause of death in the world and one of the most important risk factors for cardiovascular disease (CVD). Elevated blood pressure (BP) often coexists with lipid disorders and is an additional factor that increases CV risk. Nowadays, we are able to distinguish low density lipoproteins (LDL) and high density lipoproteins (HDL) subfractions. Except LDL also HDL small subfractions can increase the risk of CV events. Therefore, we aimed to investigate the associations between changes of lipoprotein subfractions and the risk of hypertension development.

MATERIAL AND METHODS

In 2-year long study 200 volunteers with normal blood pressure at the age of 19-32 years were included. Each volunteer underwent detailed medical examination, 12-lead electrocardiogram was taken at rest, echocardiogram, lipid subfraction assessment (using Lipoprint^®) and two 24-hour BP measurements.

RESULTS

Mean total cholesterol concentration was 189 mg/dl (4.89 mmol/l), with mean LDL concentration of 107 mg/dl (2.77 mmol/l), HDL of 63 mg/dl (1.63 mmo/l), very low-density lipoprotein (VLDL) of 40 mg/dl (1.04 mmol/l) and triglycerides (TG) of 89 mg/dl (1.00 mmol/l). Subfractions LDL 1-3 were most abundant, LDL 4-5 making up a marginal portion and LDL 6-7 were not observed. Whereas, subfractions HDL 4-6 were most abundant, in lower concentration was present HDL 1-3 and HDL 8-10. We showed that increased systolic blood pressure coreclated significantly with HDL cholesterol concentrations (p = 0.0078), HDL intermediate subgractions (p = 0.0451), with HDL-3 subfraction (p = 0.0229), and intermediate density lipoprotein-A (IDL-A) (p = 0.038). A significant correlation between increased diastolic blood pressure and HDL lipoprotein levels (p = 0.0454) was only observed.

CONCLUSIONS

Obtained results indicating correlation between total HDL levels and HDL-3 subfraction concentration (for systolic BP) and the tendency to develop hypertension.

EPHA6 rs4857055 C > T polymorphism associates with hypertension through triglyceride and LDL particle size in the Korean population

BACKGROUND

Erythropoietin-producing human hepatocellular (Eph) receptors might contribute to the development of atherosclerosis. A genome-wide association study indicated that the Eph receptor A6 gene (EPHA6) associated with at least 1 blood pressure (BP) phenotype. The objective of the present study was to determine whether EPHA6 is a novel candidate gene for hypertension in a Korean population.

METHODS

A total 2146 study participants with normotension and hypertension were included. Genotype data were obtained using a Korean Chip. To assess the association between single-nucleotide polymorphisms (SNPs) and BP, we performed a linear regression analysis, which showed that rs4850755 in the EPHA6 gene was the SNP most highly associated with both systolic and diastolic BP.

RESULTS

The presence of the TT genotype of the EPHA6 rs4857055 C > T SNP was associated with a higher risk of hypertension after adjusting for age, sex, body mass index (BMI), smoking, and drinking [odds ratio 1.533, P = 0.001]. In the control group, significant associations were observed between systolic BP and the rs4857055 polymorphism and between diastolic BP and the rs4857055 polymorphism. In the hypertension group, a significant association was observed between systolic BP and the rs4857055 polymorphism. In the hypertension group, subjects with the TT genotype showed significantly higher systolic BP than CC subjects. Additionally, in the hypertension group, TT carriers showed a higher tendency of serum triglyceride (P = 0.069) and significantly higher apolipoprotein B (P = 0.015) and smaller low-density lipoprotein (LDL) particle size (P < 0.001) than either TC or CC subjects.

CONCLUSIONS

These results could suggest that the EPHA6 rs4857055 C > T SNP is a novel candidate gene for hypertension in the Korean population. Additionally, the TT genotype could be associated with hypertriglyceridemia and small LDL particle size in hypertension.

A comparison of the genetic and clinical risk factors for arterial hypertension between indigenous and non-indigenous people of the Shoria Mountain Region

BACKGROUND

This study investigated the non-genetic and genetic risk factors for arterial hypertension (AH) in two ethnic groups living in the Mountain Shoria region: Shors and non-indigenous people.

METHODS

Clinical and epidemiological study of compactly living population in the remote areas of the Mountain Shoria (Orton, Ust-Kabyrza, Sheregesh settlements, Kemerovo region). 1178 residents of these settlements were surveyed with the help of continuous sampling method; the sample consisted of adults (18 years and older).

RESULTS

The prevalence of AH was lower in Shors (39.9% vs. 46.1%), mainly due to differences between men from the different groups: 33.2% vs. 45.8%. The percentage of people with AH, overweight, and obesity (including transabdominal obesity) in the different age groups did not differ between ethnicities. We identified statistically significant differences in the prevalence of hypertension according the two ethic groups according to age, body weight, and abdominal obesity. I/D ACE and ADRA2B polymorphisms were associated with AH. In DD ACE and DD ADRA2B carriers, there were fewer hypertensive patients in Shors than in non-indigenous people: 40.6% vs. 58.6% and 38.3% vs. 64.0%, respectively. In DD ACE carriers, more Shors had AH (60.0% vs. 37.1%).

CONCLUSION

Among Shors, the following factors increased AH risk: female sex, age, hypercholesterolemia, hyperbetacholesterinemia, hypertriglyceridemia, obesity (including transabdominal obesity), glucose intolerance, and the DD ACE, CT MTHFR, and AA ADRB1 genotypes; among the non-indigenous population, the main factors were age, hypercholesterolemia, hyperbetacholesterinemia, hypoalfacholesterinemia, hypertriglyceridemia, obesity (including transabdominal obesity), and ID ACE genotype.

Non-fasting triglycerides predict incident acute myocardial infarction among those with favourable HDL-cholesterol: Cohort Norway

AIMS

to prospectively evaluate the risk of acute myocardial infarction (AMI) associated with non-fasting triglyceride levels.

METHODS

a health survey of 140,790 Norwegians free of known coronary heart disease at baseline (1994-2003) were followed through December 2009 via record linkages to the Cause of Death Registry and hospital discharge diagnoses in the CVDNOR project, and evaluated in Cox proportional hazards analyses.

RESULTS

a total of 3219 (4.8%) men and 1434 (1.9%) women developed an AMI. Women had a steeper gradient risk with increasing triglyceride decile than men, where the highest (≥2.88 mmol/l) compared to the lowest decile (<0.7 mmol/l) was associated with an age-adjusted 4.7-fold excess risk in women in contrast to a 2.8-fold excess risk in men (interaction term, p < 0.001). A significant at-risk HDL-C (<1.0 mmol/l for men and <1.3 mmol/l for women) by triglyceride interaction term was observed. HRs increased with increasing triglyceride quartile in participants with a favourable HDL-C after multivariable adjustment (p for trend <0.001), but triglycerides did not significantly predict AMI among those with low HDL-C. For those with favourable HDL-C, net reclassification index identified a 10% and 14% improvement in classification for men and women, respectively.

CONCLUSION

non-fasting triglyceride levels among individuals with favourable HDL-C may help identify a subset of individuals at risk for CHD. Further research is warranted in evaluating non-fasting triglycerides in CHD prediction.

Insulin resistance explains the relationship between novel cardiovascular risk factors and hypertension. The Telde Study

BACKGROUND

Most studies describing an association between hypertension and an inflammatory/pro-thrombotic state do not assess insulin resistance.

AIM

To examine the association between hypertension and new cardiovascular risk factors when considering both classical risk factors and insulin resistance.

METHODS

In a population-based sample of 1030 subjects, clinical information and blood samples were obtained. Subjects were classified according to the presence or absence of hypertension, and insulin resistance was estimated using the homeostasis model of assessment (HOMA). To identify variables independently associated with hypertension, a four-model multiple logistic regression was performed: model 1 included novel risk factors (Plasminogen Activator Inhibitor- 1 [PAI-1], fibrinogen, von Willebrand Factor [vWF], lipoprotein(a), homocysteine and C-reactive Protein [CRP]); model 2, novel risk factors plus HOMA; model 3 included both classical (smoking, triglycerides, HDL cholesterol, total cholesterol, waist circumference and diabetes) and novel risk factors and model 4, model 3 plus HOMA. All were adjusted for age, BMI and gender and compared using Akaike's Information Criterion (AIC).

RESULTS

In model 1, only PAI-1, age and BMI showed association with hypertension.When HOMA and classical risk factors were also included, PAI-1 was replaced by triglyceride, smoking and diabetes. The lowest AIC value (best adjustment) was displayed by model 4, comprising all of the variables. Only age, BMI, HOMA and smoking remained significantly associated with hypertension.

CONCLUSIONS

The novel cardiovascular risk factors assessed do not add information as markers of hypertension when classical risk factors or insulin resistance are included in the evaluation.

High protein diets decrease total and abdominal fat and improve CVD risk profile in overweight and obese men and women with elevated triacylglycerol

BACKGROUND AND AIMS

It is unclear whether high protein weight loss diets have beneficial effects on weight loss, abdominal fat mass, lipids, glucose and insulin compared to conventional low fat diets in subjects at increased risk of cardiovascular disease (CVD) because of elevated glucose and triglyceride concentrations. Our objective was to determine the effects of high protein (HP) compared to standard protein (SP) diets on CVD risk in obese adults.

METHODS AND RESULTS

Data from three, 12 week, randomized parallel trials with subjects assigned to either HP or SP diet (5500-6500 kJ/day) were pooled. Weight, body composition (dual energy X-ray absorptiometry), lipids, insulin and glucose were measured before and after weight loss. Data from 215 subjects (49.9+/-9.8 years, BMI 33.5+/-3.7 kg/m(2)), 108 HP, 107 SP were analyzed. Weight loss (HP diet 7.82+/-0.37 kg; SP diet 7.65+/-0.39 kg, NS) and total fat loss were not different (HP 6.8+/-4.3 kg; LP 6.4+/-4.7 kg, NS on intention to treat analysis). The reduction in triacylglycerol (TAG) was greater on HP than SP 0.48+/-0.07 mmol/L vs 0.27+/-0.06 mmol/L, (P<0.001). Subjects with TAG greater than the median (>1.54 mmol/L at baseline) lost more weight (HP 8.5+/-0.6; SP 6.9+/-0.6 kg, P=0.01, diet by TG group), total (HP 6.17+/-0.50 kg; SP 4.52+/-0.52 kg, P=0.007) and abdominal fat (HP 1.92+/-0.17 kg; SP 1.23+/-0.19 kg, P=0.005) on HP. Total cholesterol (12 vs 6%, HP vs SP) and TAG (39 vs 20%, HP vs SP) decreased to a greater extent in these subjects (both P</=0.05) on HP.

CONCLUSION

Short-term high protein weight loss diets had beneficial effects on total cholesterol and triacylglycerol in overweight and obese subjects and achieved greater weight loss and better lipid results in subjects at increased risk of CVD. These observations provide further information regarding the utility of this dietary approach in effectively managing body weight and composition and reducing CVD risk in overweight and obese individuals.

Retinol-binding protein-4 in women with untreated essential hypertension

BACKGROUND

Retinol-binding protein-4 (RBP4) is a novel adipokine able to modulate the action of insulin in several tissues. A variable degree of insulin resistance characterizes the vast majority of hypertensive (HYP) patients. The aim of this study was to evaluate the relationship between RBP4 and essential hypertension, exploring potential links between RBP4 and other adipokines with some proxies of early vascular damage in female naive HYP patients.

METHODS

Serum RBP4, leptin, adiponectin, and resistin levels were determined in 35 HYP and 35 normotensive lean women with normal glucose tolerance paired by age and body mass index (BMI) served as controls (CTL); carotid intima-media thickness (IMT) was also measured.

RESULTS

A striking difference was observed in RBP4 levels between HYP and CTL with significantly higher levels in the former than in the latter. No relationship was observed between glomerular filtration rate (GFR) and RBP4. Adiponectin levels were slightly but significantly lower in HYP than in CTL, whereas no differences were observed in resistin and leptin concentrations between the two groups of women. In the whole study group, a strong linear relationship was observed between IMT value and both RBP4 (rho = 0.321, P = 0.0076) and resistin (rho = 0.340, P = 0.0048); these two adipocytokines, together with cholesterol, were the only variables independently related to IMT (r(2) = 0.24; P = 0.004) by a stepwise analysis.

CONCLUSIONS

RBP4 levels are increased in naive HYP women and correlated with the degree of IMT suggesting a participation of this adipocytokine in the modulation of the atherosclerotic process exerted by the adipose tissue as endocrine organ.

High-sensitivity C-reactive protein and total antioxidant status in patients with essential arterial hypertension and dyslipidemia

PURPOSE

To assess low-grade, systemic inflammation and antioxidant status as additional factors contributing to pathophysiology of essential arterial hypertension (HTN) and compare them with traditional risk factors, like abnormal lipids profile, considering their potential diagnostic usefulness.

MATERIAL AND METHODS

Serum high-sensitivity C-reactive protein (hs-CRP) concentrations and total antioxidant status (TAS) were measured in 143 subjects - 71 patients with diagnosed HTN and in 72 healthy controls.

RESULTS

In hypertensive patients, as compared to healthy control group, the median hs-CRP concentration was higher (2.0 mg/L, 25%; 75% quartile range: 0.1; 27.1 vs 0.4 mg/L, 25%; 75% quartile range: 0.0; 4.6, respectively, p<0.001) and TAS concentration lower (1.4 mmol/L, 25%; 75% quartile range: 1.0; 2.1 vs 1.5 mmol/L, 25%; 75% quartile range: 0.5; 1.8, respectively, p=0.048). Hypertensives had higher low-density lipoprotein cholesterol concentration (LDL-C) as well as triglycerides concentration (TG) and lower high-density lipoprotein cholesterol concentration (HDL-C). Higher diagnostic sensitivity was found for hs-CRP (87%) and for TAS (89%). According to the global linear regression analysis, age, gender, hs-CRP, TAS and HDL-C were the only parameters influencing the occurrence of HTN. ROC analysis identified hs-CRP, HDL-C and TG as statistically significant to diagnose HTN (0.839; 0.816 and 0.855, respectively). Moreover, in ROC analysis there were no differences in hs-CRP and TAS in females and males.

CONCLUSIONS

These results indicate that low-grade, systemic inflammation measured by hs-CRP as well as antioxidant status assessed by TAS, in the presence of traditional risk factors, are significant factors contributing to pathophysiology and diagnosis of essential arterial hypertension.

Effects of serum homocysteine and adiponectin levels on platelet aggregation in untreated patients with essential hypertension

The aim of the present study is to determine and correlate adiponectin, homocysteine, nitric oxide, and ADP-induced platelet aggregation levels in untreated patients with essential hypertension and healthy individuals. A total of 36 individuals, 23 untreated patients with essential hypertension and 13 healthy individuals, were included in the scope of this study. Enzyme-linked immunosorbent assay (ELISA) was used to determine the serum adiponectin and TNF-alpha levels. The levels of serum homocysteine were measured by using competitive chemiluminescent enzyme immunoassay. Serum concentrations of hsCRP were measured by the Nephelometer. Plasma nitrite, nitrate, and total nitric oxide (NOx) levels were determined by colorimetric method. Homocysteine and hsCRP levels in patients with essential hypertension were found to be significantly higher than those in the control group (P = 0.02, P = 0.001, respectively). The average platelet aggregation levels in patient group were higher than control group, but there were no statistically significant differences between them (P > 0.05). In addition, in patients with essential hypertension adiponectin and nitrite levels are significantly lower than control group (P < 0.001, P = 0.045, respectively). We have also found significant correlations between nitrite-platelet aggregation amplitude, nitrite-platelet aggregation slope, nitrite-adiponectin, homocysteine-platelet aggregation amplitude, and sistolic blood pressure-platelet aggregation amplitude levels (r = -0.844; P < 0.001, r = -0.680; P = 0.011, r = 0.454; P = 0.05, r = 0.414; P = 0.05, r = 0.442; P = 0.035, respectively). Increased homocysteine and decreased adiponectin serum levels in patients with essential hypertension correlate well with changes in ADP-induced conventional platelet aggregation. This association may potentially contribute to future thrombus formation and higher risks for cardiovascular events in hypertensive patients.

Effects of fluvastatin slow-release (XL 80 mg) versus simvastatin (20 mg) on the lipid triad in patients with type 2 diabetes

The lipid triad is the association of small, dense (sd) low-density lipoprotein (LDL), low high-density lipoprotein (HDL), and hypertriglyceridemia, all of which play a role in coronary artery disease in patients with type 2 diabetes. Although statins have demonstrated clear positive effects on cardiovascular morbidity/mortality in patients with diabetes and on single components of the lipid triad, it remains controversial whether they affect all components of the triad in these patients. Therefore, we performed a single-center, parallel-group, prospective, randomized, open-label, blinded-endpoint (PROBE)-type comparison of fluvastatin extended-release (XL) 80 mg (n=48) and simvastatin 20 mg (n=46), each given once daily for 2 months to patients with type 2 diabetes with the lipid triad, who were enrolled after a 1-month lifestyle modification and dietary intervention program. After fluvastatin therapy, LDL (-51%; P<.01), apolipoprotein B (ApoB; -33%; P<.01), intermediate-density LDL (idLDL) (-14.3%; P<.05), sdLDL (-45%; P<.01), and triglycerides (-38%; P<.01) were significantly decreased, and HDL (+14.3%; P<.05) and apolipoprotein A-I (ApoA-I; +7%; P<.05) were increased; large buoyant (lb) LDL did not change (P=NS). Simvastatin therapy decreased LDL (-55.1%; P<.01), ApoB (-46%; P<.01), lbLDL (-33.3%; P<.05), idLDL (-22.7%; P<.05), sdLDL (-33.3%; P<.05), and triglycerides (-47.9%; P<.01); HDL was not changed (P=NS) after simvastatin, but ApoA-I was increased (+11.3%; P<.01). HDL increases (P<.01) and sdLDL decreases (P<.01) were significantly greater after fluvastatin compared with simvastatin therapy; LDL, triglycerides, ApoB, and idLDL changes were similar after both therapies (P=NS), and lbLDL decreases were greater with simvastatin therapy (P<.05). With both treatments, classic mean LDL and ApoB target levels were achieved in most patients. We conclude that the lipid triad can be controlled with fluvastatin XL 80 mg in patients with type 2 diabetes.

Small dense low-density lipoprotein and carotid atherosclerosis in relation to vascular dementia

Vascular dementia (VaD) and Alzheimer's disease (AD) are the most common causes of dementia in the elderly. The aim of this study was to investigate carotid atherosclerosis, serum lipid profiles, and atherogenic hormone levels in nondiabetic Japanese men with VaD or AD. Carotid artery intima-media thickness (IMT) and plaque, serum lipid and lipoprotein profiles, including low-density lipoprotein (LDL) particle size, as well as insulin-like growth factor-I (IGF-I, somatomedin C) and testosterone levels, were determined in 34 patients with AD, 37 patients with VaD, and 63 healthy male controls. Age, body mass index, systolic and diastolic blood pressure, and fasting plasma glucose, hemoglobin A(1c) (HbA(1c)), triglyceride, high-density lipoprotein (HDL)-cholesterol, and apolipoproteins (apo) A-I, B, and E levels did not differ significantly among the 3 groups. However, the mean value of carotid IMT, the frequency of atherosclerotic plaque deposition, the serum levels of LDL-cholesterol, lipoprotein(a), and lipid peroxides, and the incidence of small dense LDL (particle diameter </= 25.5 nm) were increased significantly in VaD patients compared with AD patients or controls. VaD patients had a close reverse correlation between carotid IMT and LDL particle diameter, which were statistically proven independent risk factors for VaD. In contrast, AD patients had significantly lower serum levels of IGF-I and testosterone than either VaD patients or controls. Our results indicate that VaD is associated with atherogenic dyslipidemia, in particular, small dense LDL and carotid atherosclerosis, whereas AD is associated with hyposomatomedinemia and hypogonadism rather than atherosclerosis.

Atherosclerosis in type 2 diabetes mellitus and insulin resistance: mechanistic links and therapeutic targets

The ongoing heavy burden of cardiovascular disease associated with diabetes mellitus highlights the failure of current treatment strategies to address effectively the cardiovascular risk profile in such patients. Insulin resistance is not only an underlying feature in most cases of type 2 diabetes, but is also associated, through the Insulin Resistance Syndrome, with cardiovascular risk factors that promote atherothrombosis through diverse mechanisms. Growing evidence suggests that treatment with anti-diabetic agents that improve insulin sensitivity, such as the thiazolidinediones, improve multiple components of the Insulin Resistance Syndrome, have beneficial effects on various atherothrombotic mechanisms, and reduce atherosclerosis in animal models and perhaps humans as well. Given data implicating chronic inflammation as a central feature of atherosclerosis, the anti-inflammatory activity of the thiazolidinediones may contribute to their potential anti-atherosclerotic effects. An improved understanding of the mechanisms linking diabetes, atherosclerosis, and cardiovascular disease is needed in order to understand how these and other current and emerging therapies might reduce diabetes-associated cardiovascular disease.