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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.

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, S100β, 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; S100β ≥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; S100β ≥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., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Leukotriene B 4 (LTB 4 ) has been implicated in ischemic stroke pathology. We examined the prognostic significance of LTB 4 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 LTB 4 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 LTB 4 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 LTB 4 levels. In addition, neutrophil influx was also observed in the infarcted cortex. Double immunostaining indicated that neutrophils express 5-LOX and leukotriene A 4 hydrolase (LTA 4 H), highlighting the pivotal contributions of neutrophils as a source of LTB 4 . Importantly, rise in plasma LTB 4 levels corresponded with an increase in LTB 4 amount in the infarcted cortex, thereby supporting the use of plasma as a surrogate for brain LTB 4 levels. Pre-stroke LTB 4 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 LTB 4 pathway might be a viable treatment strategy for acute ischemic stroke.

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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)