Elevated C-reactive protein and long-term mortality after ischaemic stroke: relationship with markers of endothelial cell and platelet activation.

BACKGROUND AND PURPOSE: Inflammatory biomarkers predict development of atherothrombotic events. In the present study we examined the relationships between C-reactive protein (CRP), complement C3, and long-term mortality after acute ischemic stroke. METHODS: CRP and C3 were analyzed by in-house enzyme-linked immunosorbent assay in 394 subjects with acute ischemic stroke who survived for >30 days, followed-up for a median of 7.4 years. RESULTS: CRP was higher in subjects who died (10.8 mg/L; 95% CI, 9.1-12.8) compared with survivors (3.8 mg/L; 95% CI, 3.1-4.7), whereas C3 was similar in both groups (P=0.26). CRP remained predictive for mortality after adjusting for conventional clinical and demographic risk factors (the adjusted hazard ratio for those with CRP in the highest compared with the lowest quartile was 2.0; 95% CI, 1.3-3.1). However, CRP was no longer independently predictive of mortality after additionally adjusting for beta-thromboglobulin or von Willebrand factor. CONCLUSIONS: Our data suggest that the relationship between CRP and poststroke mortality may in part reflect inflammation-induced endothelial cell dysfunction and platelet activation.

Plasma angiotensin-converting enzyme in Alzheimer's disease.

The insertion allele in the gene encoding angiotensin-converting enzyme (ACE) is a risk factor for Alzheimer's disease (AD) and ACE is one of several peptidases that have the ability to degrade the neurotoxic amyloid-beta peptide. ACE is a membrane-bound peptidase that is also present in a soluble form in plasma as a result of a zinc metalloprotease-mediated shedding event. Here we aimed to determine whether there is a difference in ACE in the plasma of late-onset clinically diagnosed AD patients (n = 94) as compared to age-matched non-demented control subjects (n = 188). Plasma ACE was lower in the AD subjects as compared to the controls both at baseline (p = 0.072) and after two years (p = 0.05). There was a greater reduction in plasma ACE in the AD subjects as compared to the control subjects over the two years. Plasma ACE did not correlate with cognitive function. The observed reduction in plasma ACE in AD may reflect a general decrease in the zinc metalloprotease-mediated shedding of a subset of membrane-bound proteins.

Predictive variables for mortality after acute ischemic stroke.

BACKGROUND AND PURPOSE: Stroke is a major healthcare issue worldwide with an incidence comparable to coronary events, highlighting the importance of understanding risk factors for stroke and subsequent mortality. METHODS: In the present study, we determined long-term (all-cause) mortality in 545 patients with ischemic stroke compared with a cohort of 330 age-matched healthy control subjects followed up for a median of 7.4 years. We assessed the effect of selected demographic, clinical, biochemical, hematologic, and hemostatic factors on mortality in patients with ischemic stroke. Stroke subtype was classified according to the Oxfordshire Community Stroke Project criteria. Patients who died 30 days or less after the acute event (n=32) were excluded from analyses because this outcome is considered to be directly attributable to the acute event. RESULTS: Patients with ischemic stroke were at more than 3-fold increased risk of death compared with the age-matched control cohort. In multivariate analyses, age, stroke subtype, atrial fibrillation, and previous stroke/transient ischemic attack were predictive of mortality in patients with ischemic stroke. Albumin and creatinine and the hemostatic factors von Willebrand factor and beta-thromboglobulin were also predictive of mortality in patients with ischemic stroke after accounting for demographic and clinical variables. CONCLUSIONS: The results indicate that subjects with acute ischemic stroke are at increased risk of all-cause mortality. Advancing age, large-vessel stroke, atrial fibrillation, and previous stroke/transient ischemic attack predict mortality; and analysis of albumin, creatinine, von Willebrand factor, and beta-thromboglobulin will aid in the identification of patients at increased risk of death after stroke.

Complement C3 and C-reactive protein are elevated in South Asians independent of a family history of stroke.

BACKGROUND AND PURPOSE: Complement components are emerging risk factors for cardiovascular disease. In this study, we examined the relation among C3, C-reactive protein (CRP), factor B, and features of the insulin resistance (IR) syndrome in 143 first-degree relatives of South Asian subjects with ischemic stroke, 141 South Asian controls, and 121 white controls. METHODS: C3, CRP (high-sensitivity assay), and factor B levels were measured by ELISAs, and their relation to features of the IR syndrome were assessed. Data are presented as geometric mean (95% CI). RESULTS: There was no significant difference in the levels of C3 between South Asian relatives (1.25 [1.21, 1.29] g/L) and South Asian controls (1.20 [1.15, 1.24] g/L, P=0.2). Levels in both South Asian groups were significantly higher than in white controls (0.95 [0.92, 0.98] g/L; P<0.001 for both comparisons). These differences remained significant after adjustment for covariates. Similarly, levels of CRP were not different between the 2 South Asian groups, but levels in both South Asian groups, after adjustment for covariates, were significantly higher than in white controls. There was no difference in the levels of factor B among the 3 groups. South Asian subjects with elevated C3 levels clustered risk factors associated with IR to a greater extent than those with high CRP. CONCLUSIONS: These results suggest that South Asians have a greater level of chronic subclinical inflammation than do whites, independent of a family history of stroke. In addition, C3 is more likely to cluster with features of the IR syndrome compared with CRP in South Asians.

Proteolytic mechanisms in amyloid-beta metabolism: therapeutic implications for Alzheimer's disease.

The accumulation of the amyloid-beta peptide, the main constituent of the "amyloid plaque", is widely considered to be the key pathological event in Alzheimer's disease. Amyloid-beta is produced from the amyloid precursor protein through the action of the proteases beta-secretase and gamma-secretase. Alternative cleavage of amyloid precursor protein by the enzyme alpha-secretase precludes amyloid-beta production. In addition, several proteases are involved in the degradation of amyloid-beta. This review focuses on the proteolytic mechanisms of amyloid-beta metabolism. An increasingly detailed understanding of proteolysis in both amyloid-beta deposition and clearance has identified some of these proteases as potential therapeutic targets for Alzheimer's disease. A more complex knowledge of these proteases takes us one step closer to developing "disease-modifying" therapies, but these advances also emphasize that significant challenges must be overcome before clinically effective drugs to treat Alzheimer's disease become a reality.

Rapid draft sequencing and real-time nanopore sequencing in a hospital outbreak of Salmonella.

BACKGROUND: Foodborne outbreaks of Salmonella remain a pressing public health concern. We recently detected a large outbreak of Salmonella enterica serovar Enteritidis phage type 14b affecting more than 30 patients in our hospital. This outbreak was linked to community, national and European-wide cases. Hospital patients with Salmonella are at high risk, and require a rapid response. We initially investigated this outbreak by whole-genome sequencing using a novel rapid protocol on the Illumina MiSeq; we then integrated these data with whole-genome data from surveillance sequencing, thereby placing the outbreak in a national context. Additionally, we investigated the potential of a newly released sequencing technology, the MinION from Oxford Nanopore Technologies, in the management of a hospital outbreak of Salmonella. RESULTS: We demonstrate that rapid MiSeq sequencing can reduce the time to answer compared to the standard sequencing protocol with no impact on the results. We show, for the first time, that the MinION can acquire clinically relevant information in real time and within minutes of a DNA library being loaded. MinION sequencing permits confident assignment to species level within 20 min. Using a novel streaming phylogenetic placement method samples can be assigned to a serotype in 40 min and determined to be part of the outbreak in less than 2 h. CONCLUSIONS: Both approaches yielded reliable and actionable clinical information on the Salmonella outbreak in less than half a day. The rapid availability of such information may facilitate more informed epidemiological investigations and influence infection control practices.

Increased fibrinogen, von Willebrand factor and tissue plasminogen activator levels in insulin resistant South Asian patients with ischaemic stroke.

The aim of this study was to determine differences in atherothrombotic risk factors in South Asian subjects with a history of ischaemic stroke and South Asian subjects free from personal and family history of clinically detectable stroke. Eighty South Asian patients with ischaemic stroke (confirmed on cranial computerised scan) and 80 South Asian controls with similar age and gender distributions were recruited at random. The frequency of hypertension (P=<0.0001), myocardial infarction (P=0.003) and diabetes mellitus (<0.0001) were significantly higher in stroke patients. Stroke patients had lower high-density lipoprotein cholesterol (0.95 vs. 1.1 mmol/l, P=<0.0001), higher plasma glucose (8.1 vs. 6.6 mmol/l, P=0.01) and trendwise higher HBA(1C) (6.4 vs. 6.0%, P=0.09). There was no difference in insulin levels but insulin resistance was significantly higher in stroke patients (3.75 vs. 2.66, P=0.01). Stroke patients showed elevated levels of fibrinogen (3.78 vs. 3.41 mg/dl, P=0.02), von Willebrand factor (1.78 vs. 1.50 IU/ml, P=0.006) and tissue plasminogen activator (12.8 vs. 11.3 ng/ml, P=0.04), but the differences did not persist after adjustment for glucose, triglycerides, HDL, WHR, and BMI. Higher levels of fibrinogen, von Willebrand factor and t-PA in South Asian stroke patients disappeared after adjustment for features of insulin resistance syndrome but persisted after adjustment for presence of diabetes, confirming that these changes are essentially dependant on features of insulin resistance syndrome. A prospective study would be required to elucidate the role of thrombotic risk factors in South Asians with ischaemic stroke.

Clustering of thrombotic factors with insulin resistance in South Asian patients with ischaemic stroke.

We aimed to investigate significant correlations of insulin resistance with thrombotic factors in South Asians with stroke. Correlations of Homeostasis Model Assessment (HOMA)(as a surrogate of insulin resistance) were analysed with 6 thrombotic factors in 140 South Asian patients with a history of confirmed (by computerised tomography) ischaemic stroke. Age and sex adjusted HOMA was correlated to waist-hip ratio (r = 0.38, p = 0.0001), triglycerides (r = 0.22, p = 0.03), systolic blood pressure (r = 0.21, p = 0.04), tissue plasminogen activator (t-PA) (r = 0.22, p = 0.04); plasminogen activator inhibitor 1(PAI-1) (r = 0.26, p = 0.02); fibrinogen (r = 0.25, p = 0.02); and factor VII antigen (r = 0.21, p = 0.06). On regression analysis, with HOMA as dependent variable and significant correlates as independent variables in the model, HOMA was independently associated with PAI-1 antigen. There is extensive clustering of metabolic and thrombotic factors with insulin resistance in South Asian patients with ischaemic stroke, which may contribute to high prevalence of vascular disease in this population.

Coagulation factor VII activity, Arg/Gln353 polymorphism and features of insulin resistance in first-degree-relatives of South Asian patients with stroke.

The aim of the study was to determine associations of factor VII:C levels in 140 South Asian stroke subjects and 143 first-degree relatives versus age-sex matched 146 control subjects without a personal or a family history of stroke subjects living in UK. There were no significant differences in Factor VII:C levels or FVII Msp I gene polymorphism (Arg-Gln 353) R353Q genotype frequency between the groups. R353Q genotype determined Factor VII:C levels in all the three groups. Factor VII:C levels correlated with triglycerides (patients, r = 0.23; relatives r = 27; control subjects, r = 0.24) and plasminogen activator inhibitor activity (patients, r = 0.30; relatives r = 0.22; control subjects r = 0.20) in all the three groups, but with insulin only in patients (p = 0.19). Circulating levels of Factor VII:C are determined by R353Q genotype and cluster with other risk factors associated with insulin resistance in South Asian ischaemic stroke patients, first-degree relatives and control subjects but are not related to stroke or a family history of stroke.

Atherothrombotic risk factors in subjects with a family history of stroke.

BACKGROUND: Subjects with stroke in a first-degree relative are at increased risk of atherothrombotic vascular disease. We aimed to examine atherothrombotic risk factors in such a population. METHODS: 145 subjects with a first-degree relative with stroke and 143 controls were recruited. Measurements were made of features of the insulin resistance syndrome, haemostatic and fibrinolytic risk factors, and glucose tolerance tests. RESULTS: The relatives had higher systolic blood pressure, HDL, 2-hour glucose, factor VII:C, fibrinogen, vWF and more had smoked. Differences remained in factor VII:C, systolic BP and 2-hour glucose after adjustment. CONCLUSIONS: This population demonstrates adverse thrombotic risk factors and increased FVII:C activity may contribute to increased cardiovascular risk.

Increased fibrinogen levels among South Asians versus Whites in the United Kingdom are not explained by common polymorphisms.

Determinants of fibrinogen level among South Asians are not established. In 1997-1999, plasma fibrinogen levels and prevalences of the fibrinogen polymorphisms A alpha Thr312Ala, beta-445G/A, and B beta Arg448Lys and correlates were compared among 100 apparently healthy United Kingdom South Asians and 100 age- and sex-matched Whites. Mean fibrinogen levels were higher in South Asians (3.33 g/liter, 95% confidence interval (CI): 3.16, 3.51) than in Whites (2.84 g/liter, 95% CI: 2.72, 2.96) (p < 0.0001), but genotype distributions were similar. B beta Arg448Lys was related to fibrinogen in South Asians (RR (n = 67): 3.22 g/liter, 95% CI: 3.03, 3.43; RK (n = 26): 3.72 g/liter, 95% CI: 3.65, 4.11; KK (n = 7): 3.07 g/liter, 95% CI: 2.53, 3.72) (p = 0.04) and Whites (p = 0.06). beta-455G/A was related to fibrinogen in Whites (GG (n = 56): 2.68 g/liter, 95% CI: 2.56, 2.86; GA (n = 37): 2.97 g/liter, 95% CI: 2.79, 3.17; AA (n = 5): 3.22 g/liter, 95% CI: 2.85, 3.65) (p = 0.02) and South Asians (p = 0.07). After adjustment for age, gender, body mass index, hypertension, cholesterol, triglycerides, smoking, A alpha Thr312Ala, and beta-455G/A, fibrinogen levels remained significantly higher in South Asians (3.56 g/liter, 95% CI: 3.35, 3.77) than in Whites (3.03 g/liter, 95% CI: 2.85, 3.22) (p < 0.0001). These findings suggest that increased fibrinogen levels among South Asians versus Whites are not due to differences in the prevalence of genetic polymorphisms that encode for fibrinogen.

Determinants of plasminogen activator inhibitor-1 in South Asians with ischaemic stroke.

To investigate the relationship of circulating plasminogen activator inhibitor-1 (PAI-1) levels with features of insulin resistance and genotype at a single nucleotide insertion/deletion (4G/5G) polymorphism in the promoter region of the PAI-1 gene in 101 South Asian ischaemic stroke patients and 102 symptom-free reference subjects. The allele frequencies were 4G-0.51, 5G-0.49 and 4G-0.61, 5G-0.39 in patients and reference subjects, respectively. There was a significant association between PAI-1 promoter genotype and PAI-1 antigen levels in patients. Regression analysis with significant correlates in the model demonstrated age, gender and triglycerides in patients and fasting insulin and HDL cholesterol in reference subjects as independent predictors of PAI-1 antigen.

Factor XIII A-subunit concentration predicts outcome in stroke subjects and vascular outcome in healthy, middle-aged men.

There is growing evidence for a role of factor XIII (FXIII) in vascular disease. FXIII measures were determined in (i) a nested case-control study from the Second Northwick Park Heart Study of 63 men with myocardial infarction (MI) and 124 age-matched controls and (ii) in a case-control study of 475 subjects with acute stroke and 461 controls followed up for 54 months for mortality. In both studies, measures of FXIII A- and B-subunit antigen, FXIII activity and prothrombin fragments (F1 + 2) were made. An in vitro model was used to investigate the effects of thrombin activity on FXIII A- and B-subunit antigen levels. In study 1, patients clinically free of coronary artery disease who later developed MI had lower adjusted FXIII A-subunit levels at recruitment (129.2%vs 113.3%, P = 0.007). In study 2, stroke patients with large vessel disease had lower A-subunit antigen levels (102.1%vs 127.2%, P < 0.001), but higher F1 + 2 levels (0.941%vs 0.753%, P < 0.05), than subjects with small vessel disease. Levels of FXIII A-subunit (100%vs 117%, P < 0.0001) were lower and F1 + 2 higher (1.020%vs 0.702%, P < 0.0001) in stroke patients who had died compared with those still alive at the end of the follow-up period. Low concentrations of FXIII A-subunit antigen predicted vascular outcome in otherwise healthy subjects and relate to both size of infarct and poor post-stroke survival in patients with acute ischaemic stroke. Low in vitro concentrations of FXIII A-subunit antigen wererelated to increased thrombin generation and, thus, increased risk of thrombotic events.