Plasma NOTCH3 and the risk of cardiovascular recurrence in patients with ischemic stroke.

BACKGROUND: Ischemic stroke patients are more prone to developing another cardiovascular event. AIM: This study aims to examine potential biological predispositions to cardiovascular recurrence in patients with ischemic stroke. DESIGN: Human and preclinical studies. METHODS: Quantitative proteomic analysis, animal stroke, atherosclerosis models and circulating endothelial cells (CECs) were employed to examine candidate biomarkers derived from an ischemic stroke cohort in Singapore. RESULTS: Proteomic analysis of pooled microvesicles of "Event" (n = 24) and without "Event" (n = 24) samples identified NOTCH3 as a candidate marker; plasma NOTCH3 were shown to be elevated in "Event" patients compared to those without "Events" and age-matched controls. In a validation cohort comprising 431 prospectively recruited ischemic stroke patients (mean age 59.1 years; median follow-up 3.5 years), men with plasma NOTCH3 (>1600pg/ml) harbored increased risk of cardiovascular recurrence (adjusted hazards ratio 2.29, 95% CI 1.10-4.77); no significant association was observed in women. Chronic renal failure, peripheral artery disease and NT-pro-brain natriuretic peptide were significant predictors of plasma NOTCH3 in men without ischemic stroke (adjusted r2=0.43). Following middle cerebral artery occlusion, NOTCH3 expression in mouse sera increased and peaked at 24 hrs, persisting thereafter for at least 72 hours. In Apoe-/- atherosclerotic mice, NOTCH3 stained the endothelium of defective arterial lining and atherosclerotic plaques. Analysis of CECs isolated from stroke patients revealed increased gene expression of NOTCH3, further supporting endothelial damage underpinning NOTCH3-mediated atherosclerosis. CONCLUSION: Findings from this study suggests that NOTCH3 could be important in cardiovascular recurrence following an ischemic stroke.

Stable thyroid function despite regular use of povidone-iodine throat spray for SARS-CoV-2 prophylaxis.

BACKGROUND: It is unclear whether unintentional ingestion of povidone-iodine following its application to the oropharyngeal space could affect thyroid function. OBJECTIVE: To examine thyroid function among individuals who regularly apply povidone-iodine throat spray for SARS-CoV-2 prophylaxis. METHODS: We designed a case-control study to compare thyroid function among participants who received povidone-iodine throat spray three times a day for 42 days ('cases') and those who received vitamin C ('controls'). Thyroid function was assessed by profiling serum TSH, free T3, and free T4; iodine status was estimated using serum thyroglobulin level, while infection status was determined by measuring anti-SARS-CoV-2 antibody against the nucleocapsid antigen. All measurements were performed in pairs, at baseline and 42 days later. Pre-post changes in thyroid function were compared between groups, before and after stratification according to baseline TSH quartiles. RESULTS: A total of 177 men (117 cases and 60 controls) (mean age, 32.2 years) were included. Despite comparable demographics and clinical profiles, no clinically or statistically significant differences were observed in thyroid indices between 'cases' and 'controls' before and after stratification according to TSH quartiles. None of the participants developed symptomatic hypo- or hyperthyroidism throughout the study. Post-hoc analysis did not reveal differences in thyroid function according to infection status. CONCLUSIONS: Data from this study support the overall safety of povidone-iodine use in the oropharyngeal space for SARS-CoV-2 prophylaxis among individuals with normal thyroid function and subclinical thyroid disease.

Blood biomarkers to detect new-onset atrial fibrillation and cardioembolism in ischemic stroke patients.

BACKGROUND: Accumulating data suggest blood biomarkers could inform stroke etiology. OBJECTIVE: The purpose of this study was to investigate the performance of multiple blood biomarkers in elucidating stroke etiology with a focus on new-onset atrial fibrillation (AF) and cardioembolism. METHODS: Between January and December 2017, information on clinical and laboratory parameters and stroke characteristics was prospectively collected from ischemic stroke patients recruited from the National University Hospital, Singapore. Multiple blood biomarkers (N-terminal pro-brain natriuretic peptide [NT-proBNP], d-dimer, S100ß, neuron-specific enolase, vitamin D, cortisol, interleukin-6, insulin, uric acid, and albumin) were measured in plasma. These variables were compared with stroke etiology and the risk of new-onset AF and cardioembolism using multivariable regression methods. RESULTS: Of the 515 ischemic stroke patients (mean age 61 years; 71% men), 44 (8.5%) were diagnosed with new-onset AF, and 75 (14.5%) had cardioembolism. The combination of 2 laboratory parameters (total cholesterol ≤169 mg/dL; triglycerides ≤44.5 mg/dL) and 3 biomarkers (NT-proBNP ≥294 pg/mL; S100ß ≥64 pg/mL; cortisol ≥471 nmol/l) identified patients with new-onset AF (negative predictive value [NPV] 90%; positive predictive value [PPV] 73%; area under curve [AUC] 85%). The combination of 2 laboratory parameters (total cholesterol ≤169 mg/dL; triglycerides ≤44.5 mg/dL) and 2 biomarkers (NT-proBNP ≥507 pg/mL; S100ß ≥65 pg/mL) identified those with cardioembolism (NPV 86%; PPV 78%; AUC 87%). Adding clinical predictors did not improve the performance of these models. CONCLUSION: Blood biomarkers could identify patients with increased likelihood of cardioembolism and direct the search for occult AF.

Long-term outcomes of ischaemic stroke patients with diabetes in a multi-ethnic cohort in Singapore.

INTRODUCTION: Diabetes increases the risk of ischaemic stroke especially among Asians. This study aims to investigate contemporaneous long-term cardiovascular outcomes of ischaemic stroke patients with diabetes in a multi-ethnic Asian cohort. METHODS: Consecutive patients with ischaemic stroke were recruited from the National University Hospital, Singapore. Data on age, gender, ethnicity, risk factors (including diabetes status and body mass index [BMI]), stroke severity and mechanisms were collected. These patients were followed up until the day of the first cardiovascular event or July 2016, whichever was earlier. The primary endpoint was the time from enrolment to the first occurrence of a composite of cerebrovascular and coronary artery events. RESULTS: Between July 2011 and December 2013, 720 patients (mean age 60.6 years, 71% men, 43% with diabetes, median National Institute Health Stroke Severity scale 2) were enrolled and followed up. A total of 175 cardiovascular events occurred during a median follow-up of 3.25 years (6.90 events per 1,000 person-month), comprising 133 cerebrovascular and 42 coronary artery events. The adjusted hazard ratio of diabetes was 1.50 (95% CI 1.08-2.10). In a multivariable Cox proportional hazards model, Malay and Indian ethnicities, BMI <23kg/m2 and a prior diagnosis of diabetes were identified as independent predictors of recurrent cardiovascular events. CONCLUSION: Our study provides quantitative data on the event rates of ischaemic stroke patients with diabetes. These findings provide insights on stroke predictors in a multi-ethnic Asian population, which may have implications in the design of future interventional studies.

Heredity of type 2 diabetes confers increased susceptibility to oxidative stress and inflammation.

INTRODUCTION AND OBJECTIVE: Heredity of type 2 diabetes mellitus (T2DM) is associated with greater risk for developing T2DM. Thus, individuals who have a first-degree relative with T2DM (FDRT) provide a natural model to study factors of susceptibility towards development of T2DM, which are poorly understood. Emerging key players in T2DM pathophysiology such as adverse oxidative stress and inflammatory responses could be among possible mechanisms that predispose FDRTs to develop T2DM. Here, we aimed to examine the role of oxidative stress and inflammatory responses as mediators of this excess risk by studying dynamic postprandial responses in FDRTs. RESEARCH DESIGN AND METHODS: In this open-label case-control study, we recruited normoglycemic men with (n=9) or without (n=9) a family history of T2DM. We assessed plasma glucose, insulin, lipid profile, cytokines and F2-isoprostanes, expression levels of oxidative and inflammatory genes/proteins in circulating mononuclear cells (MNC), myotubes and adipocytes at baseline (fasting state), and after consumption of a carbohydrate-rich liquid meal or insulin stimulation. RESULTS: Postprandial glucose and insulin responses were not different between groups. Expression of oxidant transcription factor NRF2 protein (p<0.05 for myotubes) and gene (pgroup=0.002, ptime×group=0.016), along with its target genes TXNRD1 (pgroup=0.004, ptime×group=0.007), GPX3 (pgroup=0.011, ptime×group=0.019) and SOD-1 (pgroup=0.046 and ptime×group=0.191) was upregulated in FDRT-derived MNC after meal ingestion or insulin stimulation. Synergistically, expression of target genes of inflammatory transcription factor nuclear factor kappa B such as tumor necrosis factor alpha (pgroup=0.001, ptime×group=0.007) was greater in FDRT-derived MNC than in non-FDRT-derived MNC after meal ingestion or insulin stimulation. CONCLUSIONS: Our findings shed light on how heredity of T2DM confers increased susceptibility to oxidative stress and inflammation. This could provide early insights into the underlying mechanisms and future risk of FDRTs for developing T2DM and its associated complications.

Early and Sustained Increases in Leukotriene B4 Levels Are Associated with Poor Clinical Outcome in Ischemic Stroke Patients.

Leukotriene B4 (LTB4) has been implicated in ischemic stroke pathology. We examined the prognostic significance of LTB4 levels in patients with acute middle cerebral artery (MCA) infarction and their mechanisms in rat stroke models. In ischemic stroke patients with middle cerebral artery infarction, plasma LTB4 levels were found to increase rapidly, roughly doubling within 24 h when compared to initial post-stroke levels. Further analyses indicate that poor functional recovery is associated with early and more sustained increase in LTB4 rather than the peak levels. Results from studies using a rat embolic stroke model showed increased 5-lipoxygenase (5-LOX) expression in the ipsilateral infarcted cortex compared with sham control or respective contralateral regions at 24 h post-stroke with a concomitant increase in LTB4 levels. In addition, neutrophil influx was also observed in the infarcted cortex. Double immunostaining indicated that neutrophils express 5-LOX and leukotriene A4 hydrolase (LTA4H), highlighting the pivotal contributions of neutrophils as a source of LTB4. Importantly, rise in plasma LTB4 levels corresponded with an increase in LTB4 amount in the infarcted cortex, thereby supporting the use of plasma as a surrogate for brain LTB4 levels. Pre-stroke LTB4 loading increased brain infarct volume in tMCAO rats. Conversely, administration of the 5-LOX-activating protein (FLAP) inhibitor BAY-X1005 or B-leukotriene receptor (BLTR) antagonist LY255283 decreased the infarct volume by a similar extent. To conclude, targeted interruption of the LTB4 pathway might be a viable treatment strategy for acute ischemic stroke.

Stroke biomarkers in clinical practice: A critical appraisal.

Biomarkers provide critical mechanistic insights to key biologic processes that occur during cerebral ischemia which, when carefully applied, can improve clinical decision-making in acute stroke management. The translation of a blood-based biomarker in ischemic stroke to clinical practice is challenging, in part, due to the complexity of ischemic stroke pathogenesis and the presence of a blood-brain barrier that restricts the release of brain-specific markers into the circulation. The pathologic and clinical aspects of ischemic stroke are described in this review, where a non-exhaustive list of biomarkers that interrogate different aspects of ischemic stroke such as oxidative damage, inflammation, thrombus formation, cardiac function and brain injury are described. The potential roles of these biomarkers are further examined under different clinical scenarios aimed at (1) averting the risk of hemorrhagic transformation, (2) identifying individuals at risk of early neurologic deterioration and malignant infarction, (3) aiding in the diagnosis of ischemic stroke and its differentiation from other stroke mimics, (4) guiding the search for stroke etiology, and (5) assessing stroke risk within the community. Researchers should explore the roles of stroke biomarkers to enhance clinical decision-making that is presently largely based on intuition and subjective reasoning.