Lipoprotein disorder in brain infarction and hemorrhage

Soluble lectin-like oxidized low-density lipoprotein receptor-1 as a novel biomarker for large-artery atherosclerotic stroke

BACKGROUND

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) has been shown associated with the progression of atherosclerosis in endothelial cells. We sought to assess whether the baseline serum sLOX-1 levels are correlated with the presence and short-term functional outcome of large-artery atherosclerotic (LAA) stroke.

METHODS

The study recruited 241 subjects, including 148 consecutive patients with acute ischemic stroke with the subtype of LAA and 93 non-stroke controls. Clinical and laboratory data, including serum concentration of sLOX-1, were collected within 24 h of admission, and the severity of LAA stroke patients was evaluated by National Institutes of Health Stroke Scale score. And functional outcome was assessed by modified Rankin Scale three months after stroke. The association between sLOX-1 level and the functional outcome at three months was analyzed by multiple logistic regression models.

RESULTS

Serum levels of sLOX-1 in the LAA stroke patients were significantly higher as compared to normal controls (2.48 ± 0.93 ng/ml vs. 2.22 ± 0.79 ng/ml in the controls, t = 2.301, p = 0.022). The levels of serum sLOX-1 in patients with good outcome were significantly lower than those with poor outcome (2.39 ± 0.94 ng/ml vs. 2.77 ± 0.84 ng/ml, p = 0.032). After adjusting for potential confounders, sLOX-1 was still an independent predictor for the function outcome with an adjusted OR of 3.39 (95% CI, 1.61-7.11, p = 0.001).

CONCLUSIONS

The serum sLOX-1 level was higher in patients with LAA stroke, and it was an independent predictor of functional outcome in patients with LAA ischemic stroke.

HindIII polymorphism in the lipoprotein lipase gene and hypertensive intracerebral hemorrhage in the Chinese Han population

BACKGROUND

To investigate the relationship between the HindIII polymorphism and hypertensive intracerebral hemorrhage (HIH) and lipid metabolism.

METHODS

A polymerase chain reaction-restriction fragment length polymorphism assay and the chain termination DNA sequencing method were used to determine the HindIII genotypes of 267 subjects, which included 120 cerebral hemorrhagic patients and 147 controls. The fasting levels of lipids and glucose in the plasma were used to measure the effect of genotype on HIH risk factors.

RESULTS

The frequency of the T allele of the HindIII polymorphism in the HIH group was 90.8%. The frequency of the G allele was 9.2%. In the control group, the frequencies were 82.3% T and 17.7% G, which indicated that the proportion of the G allele in the HIH patient group was significantly lower than in the control group (P<.05). The frequency of GG+GT genotypes in HIH patients (P<.05) and the plasma triglyceride (TG) levels in these patients (P<.05) were also lower than in the control group. The levels of plasma TG, low-density lipoprotein cholesterol, glucose, systolic blood pressure, and diastolic blood pressure in the HIH group were higher than in the controls (P<.05). After controlling for risk factors related to HIH, the HindIII G allele was negatively correlated with the incidence of HIH (odds ratio=.417, 95% confidence interval: .193-.901).

CONCLUSIONS

The HindIII G allele may be a protective factor against the development of HIH among the Han Chinese population.

Triglycerides and risk of hemorrhagic stroke vs. ischemic vascular events: The Three-City Study

BACKGROUND

Few studies have assessed the relationship between triglycerides and the risk of hemorrhagic stroke, which contrasts the considerable number of studies about triglycerides and ischemic vascular events. We analyzed the association pattern between triglycerides and incident intracerebral hemorrhage as compared with coronary events and ischemic stroke, in a large cohort of elderly.

METHODS

Population-based, prospective cohort study among 8393 men and women participating in the Three-City Study, aged > or = 65 years at baseline. Fasting blood lipids, including triglycerides, were measured at baseline. Fatal and non-fatal strokes and coronary events were adjudicated and validated by scientific committees. Cox proportional hazards models were used to adjust for potential confounders.

RESULTS

During a mean follow-up of 5.0 years, 36 hemorrhagic strokes, 143 ischemic strokes, and 393 coronary events occurred. An increased level of triglycerides was associated with an increased risk of ischemic vascular events. Conversely, a low level of triglycerides (< or = 0.94 mmol/L) was associated with an increased risk of hemorrhagic stroke (adjusted hazard ratio 2.35; 95% confidence interval 1.18-4.70). The relationship with hemorrhagic stroke was mainly apparent in men, in individuals with high blood pressure, and in those with low levels of cholesterol.

CONCLUSIONS

In this large cohort of elderly men and women, low triglycerides levels were associated with an increased risk of hemorrhagic stroke and a decreased risk of ischemic vascular events. The association between triglycerides and hemorrhagic stroke was particularly strong in men, in subjects with high blood pressure and in those with low cholesterol levels.

LDL phenotype B and other lipid abnormalities in patients with large vessel disease and small vessel disease

BACKGROUND AND PURPOSE

Controversies concerning the significance of lipid abnormalities in stroke come mostly from the researches that studied lipid profile without considering stroke aetiologies. We investigated the prevalence of LDL phenotype B and other lipid abnormalities in stroke survivors with large vessel disease (LVD) or small vessel disease (SVD) (TOAST criteria) and in control subjects (CS).

METHODS

We studied 30 patients with LVD and 41 patients with SVD screened out of 585 stroke patients and 30 CS who fulfilled the following exclusion criteria: cardiac disorders, renal or hepatic failure, diabetes mellitus, or treatment with lipid-lowering agents. At least 3 months after stroke, the concentrations of total cholesterol (TC), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C), triglycerides (TGs), apolipoprotein E (apoE), and lipoprotein (a) [lp(a)] were measured and LDL phenotypes and apoE isoforms were identified.

RESULTS

Patients with LVD had significantly higher concentrations of LDL-C than CS (p<0.05). They had higher concentrations of TGs and lower concentrations of HDL-C than patients with SVD and CS (p<0.05). LDL phenotype B was more frequent in patients with LVD (63.3%) than in patients with SVD (39.0%) or in CS (16.7%) (p<0.05). The concentration of apoE was higher in patients with LVD than in patients with SVD or in CS (p<0.05). The percentage of patients with increased level of lp(a) (i.e., >30 mg/ml) was greater in patients with LVD (36.7%) than in CS (10%) (p<0.05).

CONCLUSIONS

Patients with stroke due to LVD, but not SVD, have high prevalence of atherogenic lipid abnormalities, including increased frequency of LDL phenotype B and higher percentage of increased lp(a) level, like patients with other atherogenic diseases.

Hyperapobetalipoproteinemia with compositional abnormality of LDL and IDL, a characteristic lipoprotein alteration in essential hypertension

The number and composition of apoprotein B (apoB)-containing lipoproteins that are very low density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) have been analyzed in subjects with essential hypertension who have no obesity and glucose intolerance. Twenty-three essential hypertensive subjects without diabetes mellitus and obesity were recruited. VLDL, IDL, LDL, and high-density lipoprotein (HDL) were separated by ultracentrifugation in the 23 hypertensive and 17 healthy subjects (control group). ApoB was determined by highly sensitive latex agglutination method in each lipoprotein fraction. There were no significant differences in age and body mass index between the hypertension and control groups. In hypertension, cholesterol levels significantly increased in plasma (13%, P < .05) and in LDL (20%, P < .05), but decreased in HDL (-14%, P < .05). Triglyceride significantly increased in plasma (66%, P < .05) and in VLDL (105%, P < .05). ApoB also significantly increased in plasma and all lipoprotein fractions except HDL. (plasma, 35%; VLDL, 94%; IDL, 82%; LDL, 42%; P < .05). With respect to lipoprotein composition, the ratio of cholesterol to apoB significantly decreased in IDL (P < .05) and LDL (P < .05). In essential hypertension, the number of apoB-containing lipoproteins (VLDL, IDL, LDL) all increased. A low ratio of cholesterol to apoB without changes in the ratio of triglyceride to apoB was noted in IDL and LDL, indicating the presence of small dense lipoprotein particles. Characteristic disorders of pure essential hypertension are characterized by hyperapobetalipoproteinemia and small dense LDL.

Development of approximate formula for LDL-chol, LDL-apo B and LDL-chol/LDL-apo B as indices of hyperapobetalipoproteinemia and small dense LDL

Estimation of LDL-chol and LDL-apo B is useful for the diagnosis of hyperapobetalipoproteinemia (normal LDL-chol with increased LDL-apo B), which is one of the most commonly occurring lipoprotein disorders associated with atherosclerotic cardiovascular diseases. The LDL-chol/LDL-apo B ratio reflects the level of small dense LDL, which is an important risk factor for IHD, CVD and ASO. In order to estimate LDL-apo B and LDL-chol/LDL-apo B ratio from blood chol, TG, HDL-chol and apo B values, we developed a formula for LDL-chol ¿0.94Chol- 0.94HDL-chol - 0.19TG¿, LDL-apo B ¿apo B - 0.09Chol + 0.09HDL-chol-0.08TG¿, and LDL-chol/LDL-apo B [¿0.94Chol-0.94HDL-chol - 0.19TG¿/¿apo B - 0.09Chol + 0.09HDL-chol-0.08TG¿] using ultracentrifugal data from 2179 subjects. These were calculated by the least squares method on the assumption that a certain compositional relationship exists between Chol, TG and apo B in VLDL, IDL and LDL. Friedewald's formula for LDL-chol (Chol - HDL-chol - 0.2TG) includes IDL-chol, but the present new formula theoretically excludes IDL-chol. It suggests a better estimation for the correct LDL-chol. Estimated LDL-apo B is useful for the diagnosis of hyperapobetalipoproteinemia and detection of small dense LDL. Without performing ultracentrifuge, additional information is obtained for the quantitative and qualitative alteration of LDL, such as small dense LDL. The above formulae and a new classification of lipoproteinemia including apo B were applied to the analyses of lipoprotein profiles of subjects with cardiovascular diseases, which were compared with those in the general population. Hyperapobetalipoproteinemia with high TG was observed 2-3 times more frequently in subjects with CAD, MI and ASO than in the Suita population. Lower ratios of LDL-chol/LDL-apo B, reflecting preponderance of small dense LDL, were observed in the above three groups. Type IIb and combined low HDL-chol were also frequent phenotypes in CAD, A-Th and ASO. The present formulae are useful for the detailed analyses of lipoprotein disorders in both qualitative as well as quantitative aspects.