Identification of Urine Metabolic Markers of Stroke Risk Using Untargeted Nuclear Magnetic Resonance Analysis.

Stroke remains the second leading cause of mortality worldwide, and the third leading cause of death and morbidity combined, affecting more than 12 million people every year. Stroke pathophysiology results from complex interactions of several risk factors related to age, family history, gender, lifestyle, and the presence of cardiovascular and metabolic diseases. Despite all the evidence, it is not possible to fully prevent stroke onset. In recent years, there has been an exploration of innovative methodologies for metabolite analysis aimed at identifying novel stroke biomarkers. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopy, we investigated small molecule variations in urine across different stages of stroke risk. The Framingham Stroke Risk Score was used in people over 63 years of age living in long-term care facilities (LTCFs) to calculate the probability of suffering a stroke: low stroke risk (LSR, control), moderate stroke risk (MSR), and high stroke risk (HSR). Univariate statistical analysis showed that urinary 4-hydroxyphenylacetate levels increased while glycolate levels decreased across the different stroke risk groups, from the LSR to the HSR groups. Trimethylamine N-oxide (TMAO) had average concentration values that were significantly higher in elderly people in the HSR group, while trigonelline levels were significantly lower in the MSR group. These metabolic markers can be used for early detection and to differentiate stages of stroke risk more efficiently.

Association of Urine Albumin-Creatinine Ratio and Cystatin C-Based Estimated GFR with Outcomes in Patients with Ischemic Stroke.

BACKGROUND/AIMS: Data about the independent and combined effects of cystatin C-based estimated glomerular filtration rate (eGFRcys) and albuminuria on the risk of poor outcome in stroke patients are limited. The aim was to elucidate how these two renal markers affect the clinical outcomes after ischemic stroke separately and jointly. METHODS: The study subjects consisted of 10,197 patients with ischemic stroke from the third China National Stroke Registry. The study outcomes were all-cause mortality, poststroke disability, recurrence of stroke, and cardiocerebral vascular disease (CVD) composite events. Cox proportional hazard models and multivariable logistic regression model were applied to evaluate the effects of eGFRcys and urine albumin-creatinine ratio (ACR) on these outcomes. RESULTS: Both reduced eGFRcys and increased ACR were independently associated with higher incidences of all-cause death and poststroke disability (p < 0.01). Mildly decreased eGFRcys (60-89 mL/min/1.73 m2) is associated with increased risk of all-cause death and poststroke disability in the presence of high-normal ACR (10-29 mg/g). Patients with both eGFRcys <45 mL/min/1.73 m2 and ACR ≥30 mg/g at baseline had a 6.8-fold risk for all-cause mortality and 3.6-fold risk for poststroke disability, compared with patients with eGFRcys of 90-119 mL/min/1.73 m2 and ACR <10 mg/g. In addition, increased ACR was associated with recurrent stroke and CVD composite event, while reduced eGFRcys showed no relationship with these outcomes. CONCLUSIONS: Both decreased eGFRcys and albuminuria are independent risk factors for all-cause death and poststroke disability. Combining the two markers is useful for improving risk stratification even in those without chronic kidney disease.

Elevated Urinary Titin and its Associated Clinical Outcomes after Acute Stroke.

INTRODUCTION: Urinary titin is a biomarker of muscle atrophy, which is a serious complication after stroke. However, there are currently no clinical data regarding urinary titin in stroke patients. METHODS: Consecutive stroke patients admitted to the stroke care unit were included. Spot urine samples were collected immediately after admission, and on days 3, 5, and 7. The primary outcome was the trend of urinary titin in patients after acute stroke. The secondary outcomes included the association between the peak urinary titin level and the modified Rankin Scale (mRS) score, the National Institutes of Health Stroke Scale (NIHSS) score, and the Barthel index (BI) upon hospital discharge. Multivariate analysis was adjusted for age, sex, NIHSS at admission, and the peak urinary titin to predict poor outcome (mRS 3-6). RESULTS: Forty-one patients were included (29 male; age, 68 ± 15 years), 29 had ischemic stroke, 8 had intracerebral hemorrhage, and 4 had subarachnoid hemorrhage. The levels of urinary titin on days 1, 3, 5, and 7 were 9.9 (4.7-21.1), 16.2 (8.6-22.0), 8.9 (4.8-15.2), and 8.7 (3.6-16.2) pmol/mg Cr, respectively. The peak urinary titin level was associated with the mRS score (r = 0.55, p < 0.01), the NIHSS score (r = 0.72, p < 0.01), and the BI (r = -0.59, p < 0.01) upon hospital discharge. In multivariate analysis, the peak urinary titin was associated with poor outcome (p = 0.03). CONCLUSIONS: Urinary titin rapidly increased after stroke and was associated with impaired functional outcomes at hospital discharge.

Potential Metabolite Biomarkers for Acute Versus Chronic Stage of Ischemic Stroke: A Pilot Study.

BACKGROUND: Metabolome profiling is used to identify biomarkers for acute ischemic stroke (AIS). Previous studies compared metabolite profiles in AIS and healthy controls, which did not account for factors that affect metabolome (genetics, medications). This pilot project evaluates the change in metabolite concentrations between the acute and chronic stage of stroke in the same cohort in order to minimize other factors impact. METHODS: We performed global metabolome profile on serum of 20 and urine of 12 stroke patients in acute (72 hours) and chronic (3-5.2 months) stage and compared relative peak values using Wilcoxon and orthogonal partial least squares discriminant analysis methods. Chronic stage metabolite concentrations were considered baseline. We performed analysis to identify significantly overrepresented pathways using MetaboAnalyst. RESULTS: Three serum metabolites asparagine (P = .045), tyrosine (P = .015), and xylose (P = .003) had significantly higher concentrations in acute stage. Seven out of top 10 serum metabolites ranked by Wilcoxon test P value were related to amino acid (AA) metabolism. Two urine metabolites glycine (P = .03) and acetylcarnitine (P = .05) had significantly different concentrations in the acute stage. Five of the top 10 urine metabolites related to AA metabolism. We identified 6 significant pathways after false discovery rate correction that were upregulated in the acute stage: (1) Aminoacyl-tRNA synthesis, (2) nitrogen, (3) alanine, aspartate, and glutamate, (4) branched-chain AA, (5) arginine and proline, and (6) phenylalanine metabolism. CONCLUSION: Longitudinal study design confirms that AA metabolism heavily involved in the pathophysiology of acute brain ischemia. Prospective longitudinal studies with a higher number of participants are needed to establish useful stroke biomarkers.

The role of blood pressure in risk of ischemic and hemorrhagic stroke in type 1 diabetes.

BACKGROUND: Hypertension is one of the strongest risk factors for stroke in the general population, while systolic blood pressure has been shown to independently increase the risk of stroke in type 1 diabetes. The aim of this study was to elucidate the association between different blood pressure variables and risk of stroke in type 1 diabetes, and to explore potential nonlinearity of this relationship. METHODS: We included 4105 individuals with type 1 diabetes without stroke at baseline, participating in the nationwide Finnish Diabetic Nephropathy Study. Mean age at baseline was 37.4 ± 11.9 years, median duration of diabetes 20.9 (interquartile range 11.5-30.4) years, and 52% were men. Office systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured. Based on these pulse pressure (PP) and mean arterial pressure (MAP) were calculated. Strokes were classified based on medical and autopsy records, as well as neuroimaging. Cox proportional hazard models were performed to study how the different blood pressure variables affected the risk of stroke and its subtypes. RESULTS: During median follow-up time of 11.9 (9.21-13.9) years, 202 (5%) individuals suffered an incident stroke; 145 (72%) were ischemic and 57 (28%) hemorrhagic. SBP, DBP, PP, and MAP all independently increased the risk of any stroke. SBP, PP, and MAP increased the risk of ischemic stroke, while SBP, DBP, and MAP increased the risk of hemorrhagic stroke. SBP was strongly associated with stroke with a hazard ratio of 1.20 (1.11-1.29)/10 mmHg. When variables were modeled using restricted cubic splines, the risk of stroke increased linearly for SBP, MAP, and PP, and non-linearly for DBP. CONCLUSIONS: The different blood pressure variables are all independently associated with increased risk of stroke in individuals with type 1 diabetes. The risk of stroke, ischemic stroke, and hemorrhagic stroke increases linearly at blood pressure levels less than the current recommended treatment guidelines.

Increased Spot Urine Albumin-to-Creatinine Ratio and Stroke Incidence: A Systematic Review and Meta-Analysis.

OBJECTIVE: This study aimed to clarify the association between an increased spot urine albumin-to-creatinine ratio (UACR) and the risk of stroke. METHODS: We performed a systematic review and meta-analysis of cohort studies, case-control studies, and ancillary data randomized controlled trials (RCTs), which were treated as cohorts in this study, and estimated the association between albuminuria, as measured with the UACR, and the risk of stroke. We performed a comprehensive search of PubMed, Embase, and the Cochrane Library and conducted a systematic review and cumulative meta-analysis of cohort studies with a cross-sectional with prospective design in which stroke incidence was reported and the baseline UACR was measured. Ancillary data from RCTs were also included as part of the cohort study. We studied the characteristics of the participants, quality scores and risk ratios (RR, with confidence intervals, CI) of stroke associated with normal and high UACRs, and we synthesized the data via a meta-analysis. RESULTS: Twelve eligible studies including a total of 32,888 participants and 3,944 cases of stroke were identified. A high UACR (>30 mg/mmol) increased the risk of stroke by 1.67 times (RR: 1.67, 95% CI: 1.49-1.86, P<0.001 I2 = 26%). The results were not different between Asian and non-Asian patients (RR: 1.64, 95% CI: 1.41-1.91, P<0.001, I2 = 23% compared with RR: 1.67, 95% CI: 1.50-1.85, P<0. 00, I2 = 39%) or between subgroups classified by old age (RR: 1.61, 95% CI: 1.39-1.88, P<0.001, I2 = 34% compared with RR: 1.68, 95% CI: 1.52-1.87, P<0.001, I2 = 13%). A sensitivity analysis did not significantly change the results. CONCLUSION: The incidence of stroke increased significantly in the high UACR group compared with the normal UACR group. The UACR could be a clinical addition for the early indication of high-risk stroke patients.

A NMR-Based Metabonomics Approach to Determine Protective Effect of a Combination of Multiple Components Derived from Naodesheng on Ischemic Stroke Rats.

Naodesheng (NDS) is a widely used traditional Chinese medicine (TCM) prescription for the treatment of ischemic stroke. A combination of 10 components is derived from NDS. They are: Notoginsenoside R1, ginsenoside Rg1, ginsenoside b1, ginsenoside Rd, hydroxysafflor yellow A, senkyunolide I, puerarin, daidzein, vitexin, and ferulic acid. This study aimed to investigate the protective effect of the ten-component combination derived from NDS (TCNDS) on ischemic stroke rats with a middle cerebral artery occlusion (MCAO) model by integrating an NMR-based metabonomics approach with biochemical assessment. Our results showed that TCNDS could improve neurobehavioral function, decrease the cerebral infarct area, and ameliorate pathological features in MCAO model rats. In addition, TCNDS was found to decrease plasma lactate dehydrogenase (LDH) and malondialdehyde (MDA) production and increase plasma superoxide dismutase (SOD) production. Furthermore, 1H-NMR metabonomic analysis indicated that TCNDS could regulate the disturbed metabolites in the plasma, urine, and brain tissue of MCAO rats, and the possible mechanisms were involved oxidative stress, energy metabolism, lipid metabolism, amino acid metabolism, and inflammation. Correlation analysis were then performed to further confirm the metabolites involved in oxidative stress. Correlation analysis showed that six plasma metabolites had high correlations with plasma LDH, MDA, and SOD. This study provides evidence that an NMR-based metabonomics approach integrated with biochemical assessment can help to better understand the underlying mechanisms as well as the holistic effect of multiple compounds from TCM.

Arsenic Exposure in Relation to Ischemic Stroke: The Reasons for Geographic and Racial Differences in Stroke Study.

BACKGROUND AND PURPOSE: The purpose of this case-cohort study was to examine urinary arsenic levels in relation to incident ischemic stroke in the United States. METHODS: We performed a case-cohort study nested within the REGARDS (REasons for Geographic and Racial Differences in Stroke) cohort. A subcohort (n=2486) of controls was randomly sampled within region-race-sex strata while all incident ischemic stroke cases from the full REGARDS cohort (n=671) were included. Baseline urinary arsenic was measured by inductively coupled plasma-mass spectrometry. Arsenic species, including urinary inorganic arsenic and its metabolites monomethylarsonic acid and dimethylarsinic acid, were measured in a random subset (n=199). Weighted Cox's proportional hazards models were used to calculate hazard ratios and 95% confidence intervals of ischemic stroke by arsenic and its species. RESULTS: The average follow-up was 6.7 years. Although incident ischemic stroke showed no association with total arsenic or total inorganic arsenic, for each unit higher level of urinary monomethylarsonic acid on a log-scale, after adjustment for potential confounders, ischemic stroke risk increased ≈2-fold (hazard ratio=1.98; 95% confidence interval: 1.12-3.50). Effect modification by age, race, sex, or geographic region was not evident. CONCLUSIONS: A metabolite of arsenic was positively associated with incident ischemic stroke in this case-cohort study of the US general population, a low-to-moderate exposure area. Overall, these findings suggest a potential role for arsenic methylation in the pathogenesis of stroke, having important implications for future cerebrovascular research.

Practical Application of Biogenic Amine Profiles for the Diagnosis of Patients with Ischemic Stroke.

BACKGROUND: Ischemic stroke (IS) is still one of the major issues in medicine. Still, early diagnosis and misdiagnosis remain the main barriers for proper patient treatment and follow-up. Exploring new potential diagnostic biomarkers for IS is relevant to decrease patient morbidity and the occurrence of poststroke diseases. Biomedical analysis could bring new light to the background of IS and-in such a way-propose new bioanalytical tools for the early diagnosis, prognostication, and monitoring of IS. MATERIALS AND METHODS: This research aimed to present a discussion on the employment of biogenic amines (BAs), as well as their precursory amino acids and main metabolites, as a new panel of biomarkers for IS. Preliminary patient data were presented and the patients were described with respect to their clinical history and examination records, as well as scientific data gained from the liquid extraction-capillary electrophoresis determination of BAs in the patients' urine samples. RESULTS: The results showed the potential of BA screening using the developed sample preparation and analysis methods in urine during IS, and this will be further studied on a more numerous group of patients with IS to reveal the usefulness of BAs as a new panel of biomarkers for early IS diagnosis and prognostication. CONCLUSIONS: To our best knowledge, this methodology for the first time has been used for the simultaneous analysis of multiple small molecular biomarkers. In addition, the factors that might influence the determination of BAs in real samples were pointed out.

Abnormal admission kidney function predicts higher mortality in stroke patients.

OBJECTIVE: To investigate the impact of abnormal kidney function on stroke outcome. METHODS: This was a retrospective cohort of stroke patients admitted to King Abdulaziz University Hospital in Kingdom of Saudi Arabia between 2010 and 2014. Serum creatinine and urine protein were collected at admis-sion. We defined proteinuria as urine protein dipstick >/=+1. Estimated glomerular filtration (eGFR) rate was calculated by Modification of Diet in Renal Disease Study equation in mL/min/1.73m2. Abnormal kidney disease was defined as Creatinine>126 mg/dl or eGFR<60. Clinical characteristics and outcomes including one-year mortality and 30-day readmission were compared between patients with versus (vs.) without abnormal kidney function and/or proteinuria. RESULTS: Out of 548 patients, 507 had creatinine measurement at admission and 193 patients had ab-normal kidney function. These patients tended to be older (median age 67 years vs. 60.5 for those with normal kidney function), men (66.7% vs. 54.3%), and hypertensive (96% vs. 88%). Diabetes prevalence did not differ between the 2 groups. Proteinuria was not associ-ated with future mortality. Abnormal kidney function was a significant predictor of post-stroke one-year mortality (adjusted OR=2.5, 95% CI=1.4 to 4.6; p-value=0.003). CONCLUSION: Abnormal kidney function doubled the risk of one-year mortality post stroke in our cohort. High-risk groups, including older hypertensive men, could be targeted for aggressive moni-toring and early treatment of risk factors.

Comparison of Associations of Reduced Estimated Glomerular Filtration Rate With Stroke Outcomes Between Hypertension and No Hypertension.

BACKGROUND AND PURPOSE: We compared the association of low estimated glomerular filtration rate (eGFR) with stroke outcomes among patients with hypertension and without hypertension. METHODS: We used the China stroke registry to identify patients on discharge with the diagnosis of stroke in 2012 and 2013. Low eGFR was defined as <60 mL/min/1.73 m2. Multivariable analysis was used to evaluate the association of low eGFR with 1-year all-cause mortality, recurrent stroke, poor functional outcome defined as 3 to 6 in modified Rankin Scale (mRS), and ordinal mRS, where the interaction of eGFR category and hypertension status was investigated. RESULTS: Of 5082 patients without hypertension, 221 patients (4.4%) had low eGFR, as compared with 1378 patients (8.6%) previously diagnosed with hypertension. In patients without hypertension, the adjusted odds ratios with 95% confidence interval of low eGFR was 1.88 (1.23-2.88) for all-cause mortality, 1.36 (0.66-2.83) for recurrent stroke, 2.14 (1.45-3.16) for poor functional outcome, and 2.07 (1.58-2.70) for ordinal mRS. In patients with hypertension, low eGFR was associated with all stroke outcomes: 1.80 (1.50-2.16) for all-cause mortality, 1.52 (1.20-1.91) for recurrent stroke, 1.30 (1.11-1.52) for poor functional outcome, and 1.31 (1.18-1.46) for ordinal mRS. The significant interaction between eGFR categories and hypertension was only found for poor functional outcome (P=0.046) and ordinal mRS (P=0.002). CONCLUSIONS: Effect of low eGFR on all-cause mortality and recurrent stroke in patients without hypertension was not significantly different from that in patients with hypertension, but low-eGFR patients without hypertension had a higher risk of stroke-related disability than those with hypertension.

Values of vanillylmandelic acid and homovanillic acid in the urine as potential prognostic biomarkers in ischaemic stroke patients.

BACKGROUND: Suitable biomarkers that have prognostic values are one of the key points of interest in ischaemic stroke. Increased sympathetic nervous system activity in ischaemic stroke causes multiple local and systemic effects that can be detrimental to the outcome. The mechanism of action is increased secretion and activity of catecholamines, whose end metabolic products are vanillylmandelic acid and homovanilic acid. Aim of our study was to determine whether these compounds can be used as potential prognostic biomarkers in ischaemic stroke, as a unique insight into the activity of the sympathetic nervous system. METHODS: Urine samples of 96 patients with ischaemic stroke and transitory ischaemic attacks were analysed. Values of vanillylmandelic and homovanillic acids in urine were tested using liquid chromatography on the first and third day post-stroke. Severity of stroke was determined using the NIHSS scale, while functional outcome was determined using the Modified Rankin Scale. RESULTS: Values of vanillylmandelic and homovanillic acids positively correlated with functional outcome of ischaemic stroke. Favorable outcomes correlated with decreased values, on contrary to increased values, which were associated with unfavourable outcomes. CONCLUSION: Determining the values of these compounds in the urine is an easily available prognostic tool for the ischaemic stroke outcome, while also influencing potential therapeutic changes.

Nitrogen balance in patients with hemiparetic stroke during the subacute rehabilitation phase.

BACKGROUND: In highly invasive diseases, metabolism commonly changes. Hypercatabolism is frequent in acute stroke, and nitrogen balance tends to be negative. However, there has been no study describing nitrogen balance in subacute and chronic stroke patients. The present study aimed to examine nitrogen balance in the subacute and chronic phases and to identify the factors related to it. METHODS: Nitrogen balance was calculated from the collected urine of 56 patients with subacute stroke [mean (SD) 53.8 (18.4) days post-stroke] who were admitted for rehabilitation for their first-ever ischaemic or nonsurgical haemorrhagic stroke. In the first experiment, their nitrogen balance was measured during the rehabilitation phase, and factors (type, severity of hemiparesis, activities of daily living, dysphagia and malnutrition status) related to it were evaluated. The second experiment was performed to describe the time course of nitrogen balance in 31 consecutive patients, with assessments made at admission and at discharge. RESULTS: Nitrogen balance was positive in all patients in the subacute phase. A significant difference was seen in nitrogen balance between high and low fat-free mass in male patients. In the chronic phase, nitrogen balance was positive in 96% of the patients. There was no significant difference in nitrogen balance between discharge and admission. CONCLUSIONS: In the subacute and chronic phases of stroke, it was confirmed that hypercatabolism had resolved and that intensive rehabilitation is possible in the convalescent period of stroke.

Urine-Specific Gravity-Based Hydration Prevents Stroke in Evolution in Patients with Acute Ischemic Stroke.

BACKGROUND: Early neurological deterioration after ischemic stroke (stroke-in-evolution [SIE]) is associated with poorer outcomes. Previous studies have demonstrated a link between hydration status and the development of SIE. In this study, we tested the hypothesis that rehydration therapy, administered on the basis of urine-specific gravity (USG) findings, might reduce the development of SIE. METHODS: We conducted a single-arm prospective study of patients with acute ischemic stroke with historical controls. For the study group, a USG higher than 1.010 was taken as an indication for rehydration. Control group patients were rehydrated without referring to USG. An increase in National Institutes of Health Stroke Scale (NIHSS) score of 4 or higher within 3 days was defined as having SIE. RESULTS: A total of 445 patients were analyzed, 167 in the study group and 278 in the control group. The proportion of patients who developed SIE was numerically, but not significantly, lower in the study group (5.9%; 10 of 167) compared with the control group (11.5%; 32 of 278). Among patients with a USG higher than 1.010 at admission, the SIE rate was significantly reduced in the study group compared with the control group (6.1% versus 16.0%; P = .021), while the rate of SIE was similar in those with a USG of 1.010 or lower at admission. Multivariate logistic regression analysis confirmed that USG-based hydration was an independent factor associated with reducing SIE. CONCLUSIONS: USG might be a convenient and useful method for guiding fluid therapy in patients with acute ischemic stroke. USG-based hydration reduced the incidence of SIE among patients with a USG higher than 1.010 at admission.

Recent Progress in Analytical Methods for Determination of Urinary 3-Hydroxypropylmercapturic Acid, a Major Metabolite of Acrolein.

3-Hydroxypropylmercapturic acid (3-HPMA), a major metabolite of acrolein in urine, has been recognized as a noninvasive biomarker of exposure to cigarette smoke. Since acrolein is formed endogenously from polyamines and is also formed during oxidative stress and aggravates tissue damage by changing protein activity through its conjugation in pathological lesions, it is thought that the urinary 3-HPMA level is useful as a biomarker to monitor the severity of several diseases related to acrolein. To study the correlation between 3-HPMA and disease severity, it is important to understand the properties of analytical methods for determination of 3-HPMA. In this article, we summarize the analytical methods for determination of urinary 3-HPMA and discuss the utility of 3-HPMA as one of the biomarkers for the diagnosis of brain infarction.

Exogenous human urinary kallidinogenase increases cerebral blood flow in patients with acute ischemic stroke.

OBJECTIVE: To study the effects of human urinary kallidinogenase (HUK) treatment on acute cerebral ischemia (ACI) using magnetic resonance perfusion weighted imaging (MRP) methods. METHODS: In a non-randomized controlled clinical trial, 30 patients diagnosed with ACI were enrolled and divided manually into 2 groups. The experimental group, consisting of 18 participants, was treated with HUK (0.15 Perinatal Assessment Unit/day) for 7 consecutive days. The control group was treated with routine medication. The participants underwent MRP examination on the first and fourteenth day after onset. The National Institutes of Health Stroke Scale (NIHSS) score, cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) were compared between the groups. RESULTS: After undergoing therapy, the experimental HUK-treated group had lower NIHSS scores than the control group (p<0.05). The CBF improved more in the HUK-treated group than in the control group (p<0.05). Additionally, MTT and TTP were shorter in the HUK-treated group than in the control group (p<0.05). CONCLUSION: Human urinary kallidinogenase improves CBF and ameliorates neurological deficits. Human urinary kallidinogenase is a safe and effective treatment approach for treating patients with ACI.

Homoarginine, arginine, and relatives: analysis, metabolism, transport, physiology, and pathology.

The year 2008 witnessed the first report on the increase in the concentration of L-homoarginine (hArg) in the maternal plasma during human pregnancy. This observation, along with a well-known function of hArg, the methylene homologue of L-arginine (Arg), as a substrate for nitric oxide (NO) synthase, was the ignition for the start of intense research on the physiology and pathology of hArg. The circulating concentration of hArg was found to be lower in patients suffering from various diseases, and hArg emerged within only very few years as a novel cardiovascular risk factor. The compendium in hand comprises original and review articles covering several aspects of hArg, Arg and its symmetrically and asymmetrically guanidine (N (G))-dimethylated derivatives SDMA and ADMA, respectively. In contrast to ADMA and SDMA, low hArg concentrations in plasma or serum and in urine are associated with high risks for morbidity and mortality, notably in the renal and cardiovascular systems. Acutely and chronically administered Arg as a nutritional supplement or in the form of dietary proteins is safe in animals and humans and leads to concomitant formation of hArg and ADMA, albeit in a different hArg/ADMA ratio. Despite the close but opposite associations of hArg and ADMA with disease in adults, children and adolescents, the underlying biochemical processes are largely unknown, presumably not restricted to NO, and warrant deeper investigation. As the common substrate for hArg and ADMA, Arg may play a key role in the biosynthesis and homeostasis of hArg and ADMA, two putative antagonists. In animal models of stroke and obesity, hArg has beneficial effects. The potential utility of hArg as a therapeutic drug or nutritional supplement in humans and animals remains to be elaborated.

Efficacy and Safety of Dabigatran Etexilate vs. Warfarin in Asian RE-LY Patients According to Baseline Renal Function or CHADS2 Score.

BACKGROUND: In Asian patients in RE-LY, dabigatran etexilate (DE) was as effective as warfarin, with a significantly lower bleeding risk. We evaluated the relationship between baseline renal function or CHADS2 score and efficacy or safety outcomes in these patients. METHODS AND RESULTS: Asian patients (n=2,782) were categorized according to baseline renal function or CHADS2 score, and efficacy and safety outcomes were analyzed for DE (110 mg and 150 mg b.i.d.) vs. warfarin. There was an increase in the rates of stroke/systemic embolism and major bleeding with worsening renal function and CHADS2 score. For stroke/systemic embolism (primary efficacy endpoint), there was no treatment interaction for dabigatran at either 110 or 150 mg b.i.d. compared with warfarin related to patients' baseline renal function (Pinteraction=0.56 for DE 110 mg and 0.62 for DE 150 mg vs. warfarin) or CHADS2 score (Pinteraction=0.68 for DE 110 mg and 0.31 for DE 150 mg vs. warfarin). For major bleeding, there was no treatment interaction by creatinine clearance category observed for either dose (Pinteraction=0.60 and 0.62 for DE 110 mg and DE 150 mg, respectively). Baseline CHADS2 score had no significant effect on bleeding event rates with DE vs. warfarin. CONCLUSIONS: Bleeding and stroke rates in Asian patients varied according to renal function and CHADS2 score, but the relative benefits of DE over warfarin were preserved when analyzed by subcategories.

Association of cyclooxygenase-2 genetic variant with cardiovascular disease.

AIM: A genetic variant (rs20417) of the PTGS2 gene, encoding for COX-2, has been associated with decreased COX-2 activity and a decreased risk of cardiovascular disease (CVD). However, this genetic association and the role of COX-2 in CVD remain controversial. METHODS AND RESULTS: The association of rs20417 with CVD was prospectively explored in 49 232 subjects (ACTIVE-A, CURE, epiDREAM/DREAM, ONTARGET, RE-LY, and WGHS) and the effect of potentially modifiable risk factors on the genetic association was further explored in 9363 INTERHEART participants. The effect of rs20417 on urinary thromboxane and prostacyclin metabolite concentrations was measured in 117 healthy individuals. Carriage of the rs20417 minor allele was associated with a decreased risk of major CVD outcomes (OR = 0.78, 95% CI: 0.70-0.87; P = 1.2 × 10(-5)). The genetic effect was significantly stronger in aspirin users (OR: 0.74, 95% CI: 0.64-0.84; P = 1.20 × 10(-5)) than non-users (OR: 0.87, 95% CI: 0.72-1.06; P = 0.16) (interaction P-value: 0.0041). Among patients with previous coronary artery disease (CAD), rs20417 carriers had a stronger protective effect on risk of major adverse events when compared with individuals without previous CAD (interaction P-value: 0.015). Carriers had significantly lower urinary levels of thromboxane (P = 0.01) and prostacyclin (P = 0.01) metabolites when compared with non-carriers. CONCLUSION: The rs20417 polymorphism is associated with a reduced risk of major cardiovascular events and lower levels of thromboxane and prostacyclin. Our results suggest that a genetic decrease in COX-2 activity may be beneficial with respect to CVD risk, especially, in higher risk patients on aspirin.

Urinary excretion of kynurenine and tryptophan, cardiovascular events, and mortality after elective coronary angiography.

AIMS: Kynurenine is a potent endothelium-derived vasodilator. Its synthesis from tryptophan is stimulated by interferon γ and may represent an important compensatory pathway for the regulation of vascular function in inflammatory conditions. We assessed associations of urine kynurenine to tryptophan ratio (KTR) levels to incident major coronary events (MCEs), acute myocardial infarction (AMI), and ischaemic stroke and mortality in patients with suspected stable coronary artery disease (CAD). METHODS AND RESULTS: A total of 3224 patients (mean age 62 years, 69% men) underwent urine and blood sampling prior to elective coronary angiography and were subsequently followed up for median 55 months. A total of 8.4% experienced an MCE, 7.8% suffered an AMI, and 7.6% died. In age- and gender-adjusted analyses, the hazard ratios [HRs; 95% confidence intervals (CI)] of MCE, AMI, and all-cause mortality were 1.43 (1.29-1.59), 1.44 (1.29-1.59), and 1.38 (1.23-1.54) per standard deviation increment of the (log-transformed) urinary KTR, respectively. These estimates were only minimally attenuated after adjustment for potential confounders. The addition of the urine KTR to a model of conventional risk factors significantly improved goodness of fit, discrimination, and risk classification for these clinical endpoints. No association was seen between the urine KTR and the risk of incident ischaemic stroke. CONCLUSION: A novel urinary inflammation marker, KTR, is strongly associated with adverse prognosis in patients with suspected stable CAD. Underlying pathomechanisms should be further elucidated.