Asymmetric dimethylarginine predicts survival in the elderly

Nitric Oxide as a Determinant of Human Longevity and Health Span

The master molecular regulators and mechanisms determining longevity and health span include nitric oxide (NO) and superoxide anion radicals (SOR). L-arginine, the NO synthase (NOS) substrate, can restore a healthy ratio between the dangerous SOR and the protective NO radical to promote healthy aging. Antioxidant supplementation orchestrates protection against oxidative stress and damage-L-arginine and antioxidants such as vitamin C increase NO production and bioavailability. Uncoupling of NO generation with the appearance of SOR can be induced by asymmetric dimethylarginine (ADMA). L-arginine can displace ADMA from the site of NO formation if sufficient amounts of the amino acid are available. Antioxidants such as ascorbic acids can scavenge SOR and increase the bioavailability of NO. The topics of this review are the complex interactions of antioxidant agents with L-arginine, which determine NO bioactivity and protection against age-related degeneration.

The role of arginine and endothelial nitric oxide synthase in the pathogenesis of Covid-19 complicated by metabolic syndrome

This literature review presents the role of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO), as well as arginine, the enzyme substrate, in the disease of metabolic syndrome and COVID-19 (SARS-CoV-2 virus). Metabolic syndrome is a combination of obesity, insulin resistance, hyperglycemia, dyslipidemia and hypertension. It has been shown that in elderly people, patients with obesity, metabolic syndrome, type 2 diabetes mellitus (DM2), and patients with COVID-19, endothelial dysfunction (ED) and vascular endothelial activation are detected. ED is the main cause of a number of pathological conditions during the development of COVID-19 and earlier in patients with metabolic syndrome, while a sharp drop in the level of nitric oxide (NO) is detected due to a decrease in the expression and activity of eNO synthase and enzyme depletion, which leads to a violation of the integrity of bloodvessels, that is, to vasoconstrictive, inflammatory and thrombotic conditions, followed by ischemia of organs and edema of tissues. It should be noted that metabolic syndrome, DM2, hypertension and obesity, in particular, are age-related diseases, and it is known that blood glucose levels increase with age, which reduces the bioavailability of NO in endothelial cells. Defects in the metabolism of NO cause dysfunction in the pulmonary blood vessels, the level of NO decreases, which leads to impaired lung function and coagulopathy. The review presents possible mechanisms of these disorders associated with ED, the release of eNO synthase, changes in phosphorylation and regulation of enzyme activity, as well as insulin resistance. A modern view of the role of the polymorphism of the eNO synthase gene in the development of these pathologies is presented. To increase the level of endothelial NO, drugs are offered that regulate the bioavailability of NO. These include arginine, agonist NO – minoxidil, steroid hormones, statins, metformin. However, further research and clinical trials are needed to develop treatment strategies that increase NO levels in the endothelium.

L-Arginine Improves Cognitive Impairment in Hypertensive Frail Older Adults

Cognitive impairment is a prevailing event in hypertensive patients and in frail older adults. Endothelial dysfunction has been shown to underlie both hypertension and cognitive dysfunction. Our hypothesis is that L-Arginine, which is known to ameliorate endothelial dysfunction, could counteract cognitive impairment in a high-risk population of hypertensive frail older adults. We designed a clinical trial to verify the effects of 4-weeks oral supplementation of L-Arginine on global cognitive function of hypertensive frail older patients. The study was successfully completed by 35 frail hypertensive elderly patients assigned to L-Arginine and 37 assigned to placebo. At follow-up, we found a significant difference in the Montreal Cognitive Assessment (MoCA) test score between the L-Arginine treated group and placebo (p: 0.0178). Moreover, we demonstrated that L-Arginine significantly attenuates Angiotensin II-induced mitochondrial oxidative stress in human endothelial cells. In conclusion, our findings indicate for the first time that oral L-Arginine supplementation significantly improves cognitive impairment in frail hypertensive older adults.

Cerebral and Systemic Stress Parameters in Correlation with Jugulo-Arterial CO2 Gap as a Marker of Cerebral Perfusion during Carotid Endarterectomy

Intraoperative stress is common to patients undergoing carotid endarterectomy (CEA); thus, impaired oxygen and metabolic balance may appear. In this study, we aimed to identify new markers of intraoperative cerebral ischemia, with predictive value on postoperative complications during CEA, performed in regional anesthesia. A total of 54 patients with significant carotid stenosis were recruited and submitted to CEA. Jugular and arterial blood samples were taken four times during operation, to measure the jugulo-arterial carbon dioxide partial pressure difference (P(j-a)CO₂), and cortisol, S100B, L-arginine, and lactate levels. A positive correlation was found between preoperative cortisol levels and all S100B concentrations. In addition, they are positively correlated with P(j-a)CO₂ values. Conversely, postoperative cortisol inversely correlates with P(j-a)CO₂ and postoperative S100B values. A negative correlation was observed between maximum systolic and pulse pressures and P(j-a)CO₂ after carotid clamp and before the release of clamp. Our data suggest that preoperative cortisol, S100B, L-arginine reflect patients' frailty, while these parameters postoperatively are influenced by intraoperative stress and injury. As a novelty, P(j-a)CO₂ might be an emerging indicator of cerebral blood flow during CEA.

An Overview of NO Signaling Pathways in Aging

Nitric Oxide (NO) is a potent signaling molecule involved in the regulation of various cellular mechanisms and pathways under normal and pathological conditions. NO production, its effects, and its efficacy, are extremely sensitive to aging-related changes in the cells. Herein, we review the mechanisms of NO signaling in the cardiovascular system, central nervous system (CNS), reproduction system, as well as its effects on skin, kidneys, thyroid, muscles, and on the immune system during aging. The aging-related decline in NO levels and bioavailability is also discussed in this review. The decreased NO production by endothelial nitric oxide synthase (eNOS) was revealed in the aged cardiovascular system. In the CNS, the decline of the neuronal (n)NOS production of NO was related to the impairment of memory, sleep, and cognition. NO played an important role in the aging of oocytes and aged-induced erectile dysfunction. Aging downregulated NO signaling pathways in endothelial cells resulting in skin, kidney, thyroid, and muscle disorders. Putative therapeutic agents (natural/synthetic) affecting NO signaling mechanisms in the aging process are discussed in the present study. In summary, all of the studies reviewed demonstrate that NO plays a crucial role in the cellular aging processes.

Arginine and Arginine/ADMA Ratio Predict 90-Day Mortality in Patients with Out-of-Hospital Cardiac Arrest-Results from the Prospective, Observational COMMUNICATE Trial

(1) Background: In patients with shock, the L-arginine nitric oxide pathway is activated, causing an elevation of nitric oxide, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) levels. Whether these metabolites provide prognostic information in patients after out-of-hospital cardiac arrest (OHCA) remains unclear. (2) Methods: We prospectively included OHCA patients, recorded clinical parameters and measured plasma ADMA, SDMA and Arginine levels by liquid chromatography tandem mass spectrometry (LC-MS). The primary endpoint was 90-day mortality. (3) Results: Of 263 patients, 130 (49.4%) died within 90 days after OHCA. Compared to survivors, non-survivors had significantly higher levels of ADMA and lower Arginine and Arginine/ADMA ratios in univariable regression analyses. Arginine levels and Arginine/ADMA ratio were significantly associated with 90-day mortality (OR 0.51 (95%CI 0.34 to 0.76), p < 0.01 and OR 0.40 (95%CI 0.26 to 0.61), p < 0.001, respectively). These associations remained significant in several multivariable models. Arginine/ADMA ratio had the highest predictive value with an area under the curve (AUC) of 0.67 for 90-day mortality. Results for secondary outcomes were similar with significant associations with in-hospital mortality and neurological outcome. (4) Conclusion: Arginine and Arginine/ADMA ratio were independently associated with 90-day mortality and other adverse outcomes in patients after OHCA. Whether therapeutic modification of the L-arginine-nitric oxide pathway has the potential to improve outcome should be evaluated.

Arginine and Endothelial Function

Arginine (L-arginine), is an amino acid involved in a number of biological processes, including the biosynthesis of proteins, host immune response, urea cycle, and nitric oxide production. In this systematic review, we focus on the functional role of arginine in the regulation of endothelial function and vascular tone. Both clinical and preclinical studies are examined, analyzing the effects of arginine supplementation in hypertension, ischemic heart disease, aging, peripheral artery disease, and diabetes mellitus.

Asymmetric Dimethylarginine Predicts One-year Recurrent Cardiovascular Events: Potential Biomarker of "Toxin Syndrome" in Coronary Heart Disease

OBJECTIVE

To examine the prognostic value of serum levels of asymmetric dimethylarginine (ADMA) in patients with stable coronary heart disease (CHD) thus explore a potential biomarker of "toxin syndrome" in CHD.

METHODS

In this prospective nested case-control study, 36 of 1,503 Chinese patients with stable CHD experienced at least 1 recurrent cardiovascular event (RCE) during 1-year follow-up. Serum levels of ADMA at the start of follow-up were compared between these 36 cases and 36 controls which matched to cases in terms of gender, age, history of hypertension, and myocardial infarction.

RESULTS

Based on the crude model, subjects in the 2 highest ADMA quartiles showed significantly higher risk of developing RCE than those in the lowest ADMA quartile [odds ratio (OR) 4.09, 95% confidence interval (CI) 1.01 to 16.58; OR 6.76, 95% CI 1.57 to 29.07]. This association was also observed in the case-mix model (OR 5.51, 95% CI 1.23 to 24.61; OR 7.83, 95% CI 1.68 to 36.41) and multivariable model (OR 6.64, 95% CI 1.40 to 31.49: OR 13.14, 95% CI 2.28 to 75.71) after adjusting for confounders. The multivariable model which combined ADMA and high-sensitivity C-reactive protein (hsCRP) showed better predictive power with areas under the receiver operator characteristic curves (0.779) than the model of either ADMA (0.694) or hsCRP (0.636).

CONCLUSION

Serum ADMA level may be a potential biomarker of "toxin syndrome" in CHD which shows favorable prognostic value in predicting 1-year RCE in patients with stable CHD. [The registration number is ChiCTR-PRNRC-07000012].

Symmetric dimethylarginine is a stronger predictor of mortality risk than asymmetric dimethylarginine among older people with kidney disease

BACKGROUND

Circulating asymmetric dimethylarginine and symmetric dimethylarginine are increased in patients with kidney disease. Symmetric dimethylarginine is considered a good marker of glomerular filtration rate, while asymmetric dimethylarginine is a marker of cardiovascular risk. However, a link between symmetric dimethylarginine and all-cause mortality has been reported. In the present study, we evaluated both dimethylarginines as risk and glomerular filtration rate markers in a cohort of elderly white individuals, both with and without chronic kidney disease.

METHODS

Glomerular filtration rate was measured in 394 individuals aged >74 years using an iohexol clearance method. Plasma asymmetric dimethylarginine, symmetric dimethylarginine and iohexol were measured simultaneously using isotope dilution tandem mass spectrometry.

RESULTS

Plasma asymmetric dimethylarginine concentrations were increased ( P < 0.01) in people with glomerular filtration rate <60 mL/min/1.73 m² compared with those with glomerular filtration rate ≥60 mL/min/1.73 m², but did not differ ( P > 0.05) between those with glomerular filtration rate 30-59 mL/min/1.73 m² and <30 mL/min/1.73 m². Plasma symmetric dimethylarginine increased consistently across declining glomerular filtration rate categories ( P < 0.0001). Glomerular filtration rate had an independent effect on plasma asymmetric dimethylarginine concentration, while glomerular filtration rate, gender, body mass index and haemoglobin had independent effects on plasma symmetric dimethylarginine concentration. Participants were followed up for a median of 33 months. There were 65 deaths. High plasma asymmetric dimethylarginine ( P = 0.0412) and symmetric dimethylarginine ( P < 0.0001) concentrations were independently associated with reduced survival.

CONCLUSIONS

Among elderly white individuals with a range of kidney function, symmetric dimethylarginine was a better marker of glomerular filtration rate and a stronger predictor of outcome than asymmetric dimethylarginine. Future studies should further evaluate the role of symmetric dimethylarginine as a marker of outcome and assess its potential value as a marker of glomerular filtration rate.

ADMA and NT pro-BNP are associated with overall mortality in elderly

BACKGROUND

Increased asymmetrical dimethylarginine (ADMA) and NT pro-BNP concentrations have been associated with mortality in patients with cardiovascular (CV) disease and the general population. The use of these prognostic markers in an older population is not established yet. The aim of the present study was to investigate the prognostic value of age, sex, BMI, co-medication and CV laboratory risk markers in geriatric care patients.

MATERIALS AND METHODS

In this prospective observational single-centre cohort study data of long-term geriatric care patients were collected. Blood samples were collected between 14.09.2009 and 16.12.2009, and mortality was recorded up to 90 months. ADMA, its symmetric isomer SDMA, L-arginine, NT pro-BNP and CRP were determined at study entry. Simple associations of risk factors for survival period were explored by Spearman correlation coefficient. Significant univariate predictors for survival period were used in the Cox proportional hazard model.

RESULTS

A total of 481 patients were screened, and data from 449 patients were analysed. A total of 381 patients died during the observation period. Full data sets from 344 patients were used for Cox regression analysis. Male sex, older age, lower BMI, use of neuroleptic medicine, peripheral artery disease, and elevated plasma concentrations of ADMA, NT pro-BNP, and CRP were significant predictors of mortality.

CONCLUSION

The concentration of ADMA and NT pro-BNP may be used as an early risk marker for overall mortality in geriatric care. Neuroleptic medicine is associated with increased mortality in this population.

Oxidative stress, aging, and diseases

Reactive oxygen and nitrogen species (RONS) are produced by several endogenous and exogenous processes, and their negative effects are neutralized by antioxidant defenses. Oxidative stress occurs from the imbalance between RONS production and these antioxidant defenses. Aging is a process characterized by the progressive loss of tissue and organ function. The oxidative stress theory of aging is based on the hypothesis that age-associated functional losses are due to the accumulation of RONS-induced damages. At the same time, oxidative stress is involved in several age-related conditions (ie, cardiovascular diseases [CVDs], chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative diseases, and cancer), including sarcopenia and frailty. Different types of oxidative stress biomarkers have been identified and may provide important information about the efficacy of the treatment, guiding the selection of the most effective drugs/dose regimens for patients and, if particularly relevant from a pathophysiological point of view, acting on a specific therapeutic target. Given the important role of oxidative stress in the pathogenesis of many clinical conditions and aging, antioxidant therapy could positively affect the natural history of several diseases, but further investigation is needed to evaluate the real efficacy of these therapeutic interventions. The purpose of this paper is to provide a review of literature on this complex topic of ever increasing interest.

The role of metabolomic markers for patients with infectious diseases: implications for risk stratification and therapeutic modulation

INTRODUCTION

Metabolomics is a rapidly growing area of research. Metabolomic markers can provide information about the interaction of different organ systems, and thereby improve the understanding of physio-pathological processes, disease risk, prognosis and therapy responsiveness in a variety of diseases. Areas covered: In this narrative review of recent clinical studies investigating metabolomic markers in adult patients presenting with acute infectious disease, we mainly focused on patients with sepsis and lower respiratory tract infections. Currently, there is a growing body of literature showing that single metabolites from distinct metabolic pathways, as well as more complex metabolomic signatures are associated with disease severity and outcome in patients with systemic infections. These pathways include, among others, metabolomic markers of oxidative stress, steroid hormone and amino acid pathways, and nutritional markers. Expert commentary: Metabolic profiling has great potential to optimize patient management, to provide new targets for individual therapy and thereby improve survival of patients. At this stage, research mainly focused on the identification of new predictive signatures and less on metabolic determinants to predict treatment response. The transition from observational studies to implementation of novel markers into clinical practice is the next crucial step to prove the usefulness of metabolomic markers in patient care.

Asymmetric dimethylarginine and all-cause mortality: a systematic review and meta-analysis

Asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), impairs the beneficial effect of NO. The predictive value of ADMA for all-cause mortality remains controversial, though it is important in the development of cardiovascular disease (CVD) and progression to dialysis in renal disease. This systematic review and meta-analysis was conducted to investigate the association between circulating ADMA and all-cause mortality. Studies with data pertinent to the association between circulating ADMA and all-cause mortality were reviewed and OR, HR or RR with 95% CI derived from multivariate Cox's proportional-hazards analysis were extracted. A total of 34 studies reporting 39137 participants were included in final analysis. The results demonstrated that circulating ADMA was independently associated with all-cause mortality (RR = 1.27, 95% CI: 1.20-1.34). The association was still statistically significant in patients with pre-existing renal disease (RR = 1.30, 95% CI: 1.19-1.43) and pre-existing CVD (RR = 1.26, 95% CI: 1.16-1.37). In those without pre-existing renal or CVD, ADMA also predicted all-cause mortality (RR = 1.31, 95% CI: 1.13-1.53). The present study suggests a positive association of circulating ADMA with all-cause mortality. Further studies are needed to investigate the effects of interventions on ADMA, and the value of ADMA as a biomarker.

Carotid Plaque Score and Risk of Cardiovascular Mortality in the Oldest Old: Results from the TOOTH Study

Aim: Accumulating evidence suggests that predictability of traditional cardiovascular risk factors declines with advancing age. We investigated whether carotid plaque scores (CPSs) were associated with cardiovascular disease (CVD) death in the oldest old, and whether asymmetrical dimethylarginine (ADMA), a marker of endothelial dysfunction, moderated the association between the CPS and CVD death.

Methods: We conducted a prospective cohort study of Japanese subjects aged ≥ 85 years without CVD at baseline. We followed this cohort for 6 years to investigate the association of CPS with CVD death via multivariable Cox proportional hazard analysis. We divided participants into three groups according to CPS (no, 0 points; low, 1.2–4.9 points; high, ≥5.0 points). The predictive value of CPS for estimating CVD death risk over CVD risk factors, including ADMA, was examined using C-statistics.

Results: We analyzed 347 participants (151 men, 196 women; mean age, 87.6 years), of which 135 (38.9%) had no carotid plaque at baseline, and 48 (13.8%) had high CPS. Of the total, 29 (8.4%) participants experienced CVD-related death during the study period. Multivariable analysis revealed a significant association of high CPS with CVD-related mortality relative to no CPS (hazard ratio, 3.90; 95% confidence interval: 1.47–10.39). ADMA was not associated with CVD death, but the significant association between CPS and CVD death was observed only in lower ADMA level. The addition of CPS to other risk factors improved the predictability of CVD death (p = 0.032).

Conclusions: High CPS correlated significantly with a higher CVD death risk in the oldest old with low cardiovascular risk. Ultrasound carotid plaque evaluation might facilitate risk evaluations of CVD death in the very old.

Admission levels of asymmetric and symmetric dimethylarginine predict long-term outcome in patients with community-acquired pneumonia

BACKGROUND

During infection, there is an activation of the L-arginine-nitric-oxide pathway, with a shift from nitric oxide synthesis to a degradation of L-arginine to its metabolites, asymmetric and symmetric dimethylarginine (ADMA and SDMA). However, the prognostic implications for short-term or long-term survival remains unclear. We investigated the association of L-arginine, ADMA, and SDMA with adverse clinical outcomes in a well-defined cohort of patients with community-acquired pneumonia (CAP).

METHODS

We measured L-arginine, ADMA, and SDMA in 268 CAP patients from a Swiss multicenter trial by mass spectrometry and used Cox regression models to investigate associations between blood marker levels and disease severity as well as mortality over a period of 6 years.

RESULTS

Six-year mortality was 44.8%. Admission levels of ADMA and SDMA (μmol/L) were correlated with CAP severity as assessed by the pneumonia severity index (r = 0.32, p < 0.001 and r = 0.56, p < 0.001 for ADMA and SDMA, respectively) and higher in 6-year non-survivors versus survivors (median 0.62 vs. 0.48; p < 0.001 and 1.01 vs. 0.85; p < 0.001 for ADMA and SDMA, respectively). Both ADMA and SDMA were significantly associated with long-term mortality (hazard ratios [HR] 4.44 [95% confidence intervals (CI) 1.84 to 10.74] and 2.81 [95% CI 1.45 to 5.48], respectively). The effects were no longer significant after multivariate adjustment for age and comorbidities. No association of L-arginine with severity and outcome was found.

CONCLUSIONS

Both ADMA and SDMA show a severity-dependent increase in patients with CAP and are strongly associated with mortality. This association is mainly explained by age and comorbidities.

TRIAL REGISTRATION

ISRCTN95122877 . Registered 31 July 2006.

l-Arginine Pathway Metabolites Predict Need for Intra-operative Shunt During Carotid Endarterectomy

OBJECTIVE/BACKGROUND

Asymmetric dimethylarginine (ADMA) inhibits nitric oxide (NO) synthesis and is a marker of atherosclerosis. This study examined the correlation between pre-operative l-arginine and ADMA concentration during carotid endarterectomy (CEA), and jugular lactate indicating anaerobic cerebral metabolism, jugular S100B reflecting blood-brain barrier integrity, and with factors of surgical intervention.

METHODS

The concentration of l-arginine, ADMA, and symmetric dimethylarginine was measured in blood taken under regional anaesthesia from the radial artery of 55 patients prior to CEA. Blood gas parameters, concentration of lactate, and S100B were also serially measured in blood taken from both the radial artery and the jugular bulb before and after carotid clamping, and after release of the clamp. To estimate anaerobic metabolism, the jugulo-arterial ratio of CO₂ gap/oxygen extraction was calculated.

RESULTS

Positive correlation was found between pre-operative ADMA levels and the ratio of jugulo-arterial CO₂ gap/oxygen extraction during clamp and reperfusion (p = .005 and p = .01, respectively). An inverse correlation was found between the pre-operative l-arginine concentration and jugular lactate at each time point (both p = .002). The critical pre-operative level of l-arginine was determined by receiver operator curve analysis. If l-arginine was below the cutoff value of 35 μmol/L, jugular S100B concentration was higher 24 h post-operatively (p = .03), and jugular lactate levels were increased during reperfusion (p = .02). The median pre-operative concentration of l-arginine was lower in patients requiring an intra-operative shunt than in patients without need of shunt (median: 30.3 μmol/L [interquartile range 24.4-34.4 μmol/L] vs. 57.6 μmol/L [interquartile range 42.3-74.5 μmol/L]; p = .002).

CONCLUSION

High pre-operative ADMA concentration predicts poor cerebral perfusion indicated by elevated jugulo-arterial CO₂ gap/oxygen extraction. Low pre-operative l-arginine concentration predicts the need for a shunt. The inverse correlation between pre-operative l-arginine concentration and both jugular lactate and S100B during carotid clamping suggests a protective role of the NO donor l-arginine.

Asymmetric and Symmetric Dimethylarginine as Risk Markers for Total Mortality and Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Studies

Background

A growing number of studies linked elevated concentrations of circulating asymmetric (ADMA) and symmetric (SDMA) dimethylarginine to mortality and cardiovascular disease (CVD) events. To summarize the evidence, we conducted a systematic review and quantified associations of ADMA and SDMA with the risks of all-cause mortality and incident CVD in meta-analyses accounting for different populations and methodological approaches of the studies.

Methods

Relevant studies were identified in PubMed until February 2015. We used random effect models to obtain summary relative risks (RR) and 95% confidence intervals (95%CIs), comparing top versus bottom tertiles. Dose-response relations were assessed by restricted cubic spline regression models and potential non-linearity was evaluated using a likelihood ratio test. Heterogeneity between subgroups was assessed by meta-regression analysis.

Results

For ADMA, 34 studies (total n = 32,428) investigating associations with all-cause mortality (events = 5,035) and 30 studies (total n = 30,624) investigating the association with incident CVD (events = 3,396) were included. The summary RRs (95%CI) for all-cause mortality were 1.52 (1.37–1.68) and for CVD 1.33 (1.22–1.45), comparing high versus low ADMA concentrations. Slight differences were observed across study populations and methodological approaches, with the strongest association of ADMA being reported with all-cause mortality in critically ill patients. For SDMA, 17 studies (total n = 18,163) were included for all-cause mortality (events = 2,903), and 13 studies (total n = 16,807) for CVD (events = 1,534). High vs. low levels of SDMA, were associated with increased risk of all-cause mortality [summary RR (95%CI): 1.31 (1.18–1.46)] and CVD [summary RR (95%CI): 1.36 (1.10–1.68) Strongest associations were observed in general population samples.

Conclusions

The dimethylarginines ADMA and SDMA are independent risk markers for all-cause mortality and CVD across different populations and methodological approaches.

Vascular risk assessment in older adults without a history of cardiovascular disease

Modern cardiovascular risk prediction tools, which have their genesis in the Framingham Heart Study, have allowed more accurate risk stratification and targeting of treatments worldwide over the last seven decades. Better cardiovascular risk factor control during this time has led to a reduction in cardiovascular mortality and, at least in part, to improved life expectancy. As a result, western societies as a whole have seen a steady increase in the proportion of older persons in their populations. Unfortunately, several studies have shown that the same tools which have contributed to this increase cannot be reliably extrapolated for use in older generations. Recent work has allowed recalibration of existing models for use in older populations but these modified tools still require external validation before they can be confidently applied in clinical practice. Another complication is emerging evidence that aggressive risk factor modification in older adults, particularly more frail individuals, may actually be harmful. This review looks at currently available cardiovascular risk prediction models and the specific challenges faced with their use in older adults, followed by analysis of recent attempts at recalibration for this cohort. We discuss the issue of frailty, looking at our evolving understanding of its constituent features and various tools for its assessment. We also review work to date on the impact of frailty on cardiovascular risk modification and outline its potentially central role in determining the most sensible approach in older patients. We summarise the most promising novel markers of cardiovascular risk which may be of use in improving risk prediction in older adults in the future. These include markers of vascular compliance (such as aortic pulse wave velocity and pulse wave analysis), of endothelial function (such as flow mediated dilation, carotid intima-media thickness and coronary artery calcium scores), and also biochemical and circulating cellular markers.

Angiotensin converting enzyme inhibition increases ADMA concentration in patients on maintenance hemodialysis--a randomized cross-over study

Background

Endothelial dysfunction occurs in patients with end-stage renal disease (ESRD) and is associated with increased cardiovascular morbidity and mortality. Asymmetric dimethylarginine (ADMA) contributes to endothelial dysfunction in ESRD. In the general population, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) decrease ADMA levels, but no study has compared the effect of these drugs in patients with ESRD on maintenance hemodialysis (MHD).

Methods

We evaluated the effect of 1-week treatment with ramipril (5 mg/d), valsartan (160 mg/d), and placebo on ADMA levels in 15 patients on MHD in a double-blind, placebo-controlled, three x three cross-over study.

Results

We found that ADMA levels were increased at baseline and throughout the dialysis session during ramipril treatment (p < 0.001 compared to both, placebo and valsartan). Ramipril did not increase ADMA levels in a study of patients without ESRD, suggesting that factors related to ESRD or hemodialysis contribute to the ACE inhibitor-induced increase in ADMA. We have previously shown that ACE inhibition increases bradykinin (BK) levels during hemodialysis. We therefore evaluated the effect of bradykinin on ADMA production in A549 cells; a cell line that expresses BK receptors. Incubation with BK increased intracellular ADMA concentration through BK B2-receptor stimulation.

Conclusion

These data indicate that short-term ACE inhibition increases ADMA in patients on MHD whereas ARBs do not. In vitro studies further suggest that this may occur through BK-mediated increase in ADMA production during ACE inhibition.

Trial registration

Clinicaltrials.gov NCT00732069 August 6 2008 and NCT00607672 February 4 2008

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0162-x) contains supplementary material, which is available to authorized users.

Systematic review regarding metabolic profiling for improved pathophysiological understanding of disease and outcome prediction in respiratory infections

Metabolic profiling through targeted quantification of a predefined subset of metabolites, performed by mass spectrometric analytical techniques, allows detailed investigation of biological pathways and thus may provide information about the interaction of different organic systems, ultimately improving understanding of disease risk and prognosis in a variety of diseases. Early risk assessment, in turn, may improve patient management in regard to cite-of-care decisions and treatment modalities. Within this review, we focus on the potential of metabolic profiling to improve our pathophysiological understanding of disease and management of patients. We focus thereby on lower respiratory tract infections (LRTI) including community-acquired pneumonia (CAP) and chronic obstructive pulmonary disease (COPD), an important disease responsible for high mortality, morbidity and costs worldwide. Observational data from numerous clinical and experimental studies have provided convincing data linking metabolic blood biomarkers such as lactate, glucose or cortisol to patient outcomes. Also, identified through metabolomic studies, novel innovative metabolic markers such as steroid hormones, biogenic amines, members of the oxidative status, sphingo- and glycerophospholipids, and trimethylamine-N-oxide (TMAO) have shown promising results. Since many uncertainties remain in predicting mortality in these patients, further prospective and retrospective observational studies are needed to uncover metabolic pathways responsible for mortality associated with LRTI. Improved understanding of outcome-specific metabolite signatures in LRTIs may optimize patient management strategies, provide potential new targets for future individual therapy, and thereby improve patients' chances for survival.

Asymmetric dimethylarginine and cardiovascular risk: systematic review and meta-analysis of 22 prospective studies

BACKGROUND

Asymmetric dimethylarginine (ADMA) inhibits the production of nitric oxide, a key regulator of the vascular tone, and may be important in the development of cardiovascular disease (CVD). Our aim was to reliably quantify the association of ADMA and its isomer symmetric dimethylarginine (SDMA) with the risk of CVD outcomes in long-term cohort studies.

METHODS AND RESULTS

Data were collated from 22 prospective studies involving a total of 19 842 participants, which have recorded 2339 CVD, 997 coronary heart disease, and 467 stroke outcomes during a mean follow-up of 7.1 years. In a comparison of individuals in the top with those in the bottom third of baseline ADMA values, the combined risk ratios were 1.42 (95% confidence interval: 1.29 to 1.56) for CVD, 1.39 for coronary heart disease (1.19 to 1.62), and 1.60 for stroke (1.33 to 1.91). Broadly similar results were observed according to participants' baseline disease status (risk ratios for CVD: 1.35 [1.18 to 1.54] in general populations; 1.47 [1.16 to 1.87] in individuals with pre-existing CVD; and 1.52 [1.26 to 1.84] in individuals with pre-existing kidney disease) and by different study characteristics, including geographical location, sample type, assay method, number of incident outcomes, and level of statistical adjustment (all P values>0.05). In contrast, in 8 prospective studies involving 9070 participants and 848 outcomes, the corresponding estimate for SDMA concentration was 1.32 (0.92 to 1.90) for CVD.

CONCLUSIONS

Available prospective studies suggest associations between circulating ADMA concentration and CVD outcomes under a broad range of circumstances. Further research is needed to better clarify these associations, particularly in large general population studies.

Estimated GFR is biased by non-traditional cardiovascular risk factors

BACKGROUND

Estimated glomerular filtration rate (eGFR) based on either cystatin C or creatinine performs similarly in estimating measured GFR, but associate differently with cardiovascular disease (CVD) and mortality. This could be due to confounding by non-GFR-related traits associated with cystatin C and creatinine levels. We investigated non-GFR-related associations between eGFR and two types of nontraditional risk factors for CVD and death: L-arginine/dimethylarginine metabolism and insulin resistance.

METHODS

GFR was measured via iohexol clearance in a cross-sectional study of 1,624 middle-aged persons from the general population without CVD, diabetes or chronic kidney disease. The dimethylarginines were measured using liquid chromatography tandem mass spectrometry (LC-MSMS). Insulin resistance was determined by the homeostasis model assessment (HOMA-IR).

RESULTS

Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), the L-arginine/ADMA ratio and insulin resistance were associated with creatinine-based eGFR after accounting for measured GFR in multivariable adjusted analyses. The cystatin C-based eGFR showed a similar residual association with SDMA; an oppositely directed, borderline significant association with ADMA; and a stronger residual association with insulin resistance compared with eGFR based on creatinine.

CONCLUSION

Both creatinine- and cystatin C-based eGFR are influenced by nontraditional risk factors, which may bias risk prediction by eGFR in longitudinal studies.

Plasma arginine/ADMA ratio as a sensitive risk marker for atherosclerosis: Shimane CoHRE study

BACKGROUND

Asymmetric dimethylarginine (ADMA), which acts an endogenous inhibitor of nitric oxide synthase (NOS), is involved in the pathogenesis of cardiovascular disease. Arginine (Arg) may regulate vascular endothelial function, since Arg is the substrate of NO competing with ADMA. In our previous study, low Arg/ADMA ratio is an independent risk for microangiopathy-related cerebral damage.

PURPOSE

Here, we performed a cross-sectional study to evaluate the association between the Arg/ADMA ratio and the maximal intima-media thickness (IMT) in the carotid artery.

SUBJECTS AND METHODS

Participants were 785 community-dwelling Japanese people without any severe disorders. Plasma concentration of Arg and ADMA in fasting blood sample was determined using HPLC. IMT was measured in the bilateral carotid artery by ultrasonography.

RESULTS

Among quartiles stratified by the Arg/ADMA ratio, ANOVA showed a significant difference in IMT and the IMT in Q1 (the lowest quartile) was significantly higher than that in Q4 (the highest quartile). In multiple linear regression analysis, age, the male gender, lower BMI, the presence of hypertension and lower Arg/ADMA ratio were independently correlated with IMT, while IMT was not correlated with Arg or ADMA alone. In addition, the Arg/ADMA ratio was associated with IMT independent of age, sex, BMI and the presence of hypertension with odds ratio 0.21 (95%CI: 0.05-0.88) in multiple logistic regression analysis for IMT 1.5 mm or more.

CONCLUSION

Imbalance of Arg and ADMA is independently involved in the progression of atherosclerosis, and the Arg/ADMA ratio may be a sensitive marker for atherosclerosis.

The aging kidney revisited: a systematic review

As for the whole human body, the kidney undergoes age-related changes which translate in an inexorable and progressive decline in renal function. Renal aging is a multifactorial process where gender, race and genetic background and several key-mediators such as chronic inflammation, oxidative stress, the renin-angiotensin-aldosterone (RAAS) system, impairment in kidney repair capacities and background cardiovascular disease play a significant role. Features of the aging kidney include macroscopic and microscopic changes and important functional adaptations, none of which is pathognomonic of aging. The assessment of renal function in the framework of aging is problematic and the question whether renal aging should be considered as a physiological or pathological process remains a much debated issue. Although promising dietary and pharmacological approaches have been tested to retard aging processes or renal function decline in the elderly, proper lifestyle modifications, as those applicable to the general population, currently represent the most plausible approach to maintain kidney health.

Melatonin and its atheroprotective effects: a review

Atherosclerosis is a chronic vascular disease in which oxidative stress and inflammation are commonly implicated as major causative factors. Identification of novel strategies that contribute to plaque stabilization or inhibition represents a continuing challenge for the medical community. The evidence from the last decade highlights that melatonin influences the cardiovascular system, but its mechanisms of action have not been definitively clarified. Melatonin has atheroprotective effects by acting on different pathogenic signaling processes; these result from its direct free radical scavenger activity, its indirect antioxidant properties and its anti-inflammatory actions. In this review, we summarize the many pieces of the puzzle which identified molecular targets for prevention and therapy against the atherosclerotic pathogenic processes and we evaluate the data documenting that melatonin treatment has important actions that protect against atherosclerosis and atherosclerosis-related cardiovascular diseases.

The asymmetric dimethylarginine level is associated with the predicted stroke risk in Japanese women

AIM

Asymmetric dimethylarginine(ADMA) has recently been investigated as a risk marker for cardio- and cerebrovascular diseases. However, it is not currently known whether the ADMA levels are related to the risk of stroke in Japanese women.

METHODS

We examined 192 Japanese women(mean age, 55±9 years, range, 40-80 years) who underwent health examinations. The ADMA level and various vascular risk factors of each subject were assessed, and the predicted 10-year stroke risk was calculated using the point-based prediction model provided by the Japan Public Health Center study.

RESULTS

In a correlation coefficient analysis, age was found to be the only factor significantly correlated with the ADMA level. A significant odds ratio (OR) for a high predicted stroke risk(10-year risk, ≥5%) was noted in the highest ADMA level tertile(6.24; 95% CI, 1.13-34.5; p=0.036) compared with the lowest tertile, after adjusting for potential confounding factors. A significant OR for a high predicted stroke risk was also found for each increment in the ADMA tertile and standard deviation(adjusted OR, 2.42; 95% CI, 1.09-5.34; p=0.029; and 2.51; 95% CI, 1.24-5.11; p=0.011, respectively).

CONCLUSIONS

An elevated ADMA level is significantly associated with an increased predicted stroke risk, suggesting that measuring the ADMA level is useful for identifying Japanese women with an elevated stroke risk.