Plasma levels of thrombomodulin and lipoprotein (a) in patients with cerebral thrombosis

Lipoprotein (a) level as a risk factor for stroke and its subtype: A systematic review and meta-analysis

The role of lipoprotein-A [Lp (a)] as a risk factor for stroke is less well documented than for coronary heart disease. Hence, we conducted a systematic review and meta-analysis for the published observational studies in order to investigate the association of Lp (a) levels with the risk of stroke and its subtypes. In our meta-analysis, 41 studies involving 7874 ischemic stroke (IS) patients and 32,138 controls; 13 studies for the IS subtypes based on TOAST classification and 7 studies with 871 Intracerebral hemorrhage (ICH) cases and 2865 control subjects were included. A significant association between increased levels of Lp (a) and risk of IS as compared to control subjects was observed (standardized mean difference (SMD) 0.76; 95% confidence interval (CIs) 0.53-0.99). Lp (a) levels were also found to be significantly associated with the risk of large artery atherosclerosis (LAA) subtype of IS (SMD 0.68; 95% CI 0.01-1.34) as well as significantly associated with the risk of ICH (SMD 0.65; 95% CI 0.13-1.17) as compared to controls. Increased Lp (a) levels could be considered as a predictive marker for identifying individuals who are at risk of developing IS, LAA and ICH.

Lipoprotein (a) and Stroke

Background and Purpose— The relationship between elevated lipoprotein (a) levels[Lp(a)] and stroke is controversial. We systematically reviewed the literature to determine whether Lp(a) is a risk factor for stroke.

Methods— We searched MEDLINE (1966 to 2006), EMBASE (1974 to 2006), and Google scholar for articles on Lp(a) and cerebrovascular disease. From potentially relevant references retrieved, we excluded uncontrolled studies, studies of children with stroke, studies investigating carotid atherosclerosis, and studies lacking adequate data.

Results— Thirty-one studies comprising 56 010 subjects with >4609 stroke events met all inclusion criteria and were included in the meta-analysis. In case-control studies (n=23 with 2600 strokes) unadjusted mean Lp(a) was higher in stroke patients (standardized mean difference, 0.39; 95% CI, 0.23 to 0.54) and was more frequently abnormally elevated (OR, 2.39; 95% CI, 1.57 to 3.63). Sensitivity analysis and meta-regression did not find any influence of study design, measurement period of Lp(a) in relationship to stroke episode, subtype, age, and sex to explain the substantial heterogeneity between studies (I 2 =83.7%; P <0.001). There was no evidence of publication bias. In nested case-control studies (n=3 with 364 strokes) Lp(a) was not a risk factor for incident stroke (OR, 1.04; 95% CI, 0.6 to 1.8). In prospective cohort studies (n=5 with >1645 strokes), incident stroke was more frequent in patients in the highest tertile of Lp(a) distribution compared with the lowest tertile of Lp(a) (RR, 1.22; 95% CI, 1.04 to 1.43). There was no publication bias or heterogeneity in the prospective studies (I 2 =0.00%; P =0.67).

Conclusion— This meta-analysis suggests that elevated Lp(a) is a risk factor for incident stroke.

Association study of the thrombomodulin −33G>A polymorphism with coronary artery disease and myocardial infarction in Chinese Han population

BACKGROUND

Thrombomodulin (TM) is the anticoagulant endothelial cell membrane-bound protein cofactor in the thrombin-mediated activation of protein C. Recently, conflicting data have been reported regarding the possible contribution of the TM -33G>A polymorphism to coronary artery disease (CAD) or myocardial infarction (MI) in some Asian populations. We investigated this polymorphism in northern Han Chinese.

METHODS

We performed a case-control study, including 808 patients with angiographically verified CAD or a history of an acute MI and 813 age- and sex-matched controls. The TM -33G>A polymorphism was determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

We did not find a significant difference in the frequency of the A allele between CAD patients (11%) and controls (9.8%; P=0.249), between MI patients (11.5%) and controls (P=0.163), or between premature MI patients (11.7%) and controls (P=0.265). Similarly, the difference of the genotypic distributions could be neglected across the groups: GG: (GA/AA) was 81.4%:18.6% in controls, 79.7%:20.3% in patients with CAD, 78.8%:21.2% in patients with MI, and 77.7%:22.3% in patients with premature MI, respectively (vs. controls, all P>0.05). The lack of association also persisted after adjusting for other conventional risk factors.

CONCLUSIONS

Our results seemed not to support a significant association of the TM -33G>A polymorphism with CAD, MI or premature MI in our population.

Coagulation and inflammatory markers in Alzheimer's and vascular dementia

Alzheimer's disease is classified as a degenerative dementia while vascular dementia is known to be associated with atherothrombosis and classical vascular risk factors. However, over the last decade, there is increasing evidence of the role of haemostatic factors and inflammatory mechanisms in the pathogenesis of Alzheimer's disease. Serum markers of hypercoagulability and markers of inflammation could lead to thrombosis, accelerated atherogenesis and resulting dementia of both Alzheimer's and vascular dementia. In this case control study, we studied these serum markers of coagulation and inflammation in patients suffering from dementia.

Thrombomodulin as a marker of endothelium damage in some clinical conditions

Background: Thrombomodulin (TM) is a membrane glycoprotein in the vascular endothelium. It may be cleaved from endothelial cells and released into the circulation. The plasma TM level depends on the integrity of the endothelium and the clearance of the molecule. The physiological role of soluble TM forms is still unclear. The clinical significance of elevated levels of TM in various pathologic conditions is not well established yet. To analyze variations of plasma TM level in different clinical situations, its concentrations in patients with three groups of diseases were measured and compared with those in healthy subjects. Methods: Plasma samples from 23 patients at risk for development of vascular complications [essential hypertension (EH), stages 1 and 2], 31 patients with inflammatory bowel diseases [Crohn's disease (IBD), mostly in the active stage], and 19 patients with malignant tumors [gastric carcinoma (NEO)], were analyzed for soluble TM with an enzyme immunoassay kit. Results: In the group of patients with the early stages of EH and with non-active IBD, no significant changes were found in comparison to the healthy subjects. In the patients with active IBD and mainly with NEO, soluble TM was significantly increased (P<0.05 and P<0.001, respectively). Conclusions: Our TM levels failed to demonstrate increased endothelial damage in the early stage of EH. This suggests that TM is released into the plasma only by true endothelial cell damage during the development of vascular complications. Probably a certain degree of endothelial injury is necessary for an increase in plasma. In the active stage of IBD and in NEO, soluble TM appears to be derived not only from injured endothelial cells, but may also be proteolytically cleaved from membrane TM by proteases. There may also be increased synthesis of TM in activated and/or transformed cells.