Uric acid increases the incidence of ventricular arrhythmia in patients with left ventricular hypertrophy

Urate-lowering therapy is associated with a reduced risk of arrhythmias: a systematic review and meta-analysis

Objective

While urate-lowering therapy (ULT) is linked to increased cardioprotective benefits on primary prevention of cardiovascular events such myocardial infarction or heart failure, little is known regarding their effects on arrhythmia risk. The purpose of this study was to investigate the relationship between incident arrhythmias and ULT.

Methods

We searched MEDLINE and Embase from inception to May 2023. Included studies were randomized controlled trials and cohort studies that compared the risk of cardiac arrhythmias among ULT users with non-ULT users.

Results

A total of 12,420 patients from five studies were analyzed, comprising 7,359 subjects in the ULT group and 5,061 subjects in the non-ULT group. Our results showed that ULT users had significant reductions in the risk of arrhythmias (pooled relative risk [RR] 0.82, 95% confidence interval [CI] 0.74~0.92, p<0.001, I2=0.0%) compared to non-ULT users. Subgroup analysis did not show that ULT users had a significant reduced risk of atrial fibrillation (pooled RR 0.76, 95% CI 0.54~1.05, p=0.096 with I2=15.4%) compared to non-ULT users.

Conclusion

ULT is associated with lower risk of overall arrhythmias. Further studies are warranted to confirm our findings.

Serum uric acid and the risk of ventricular arrhythmias: a systematic review

Uric acid (UA) is the end product of purine degradation in humans. It promotes inflammation via activation of pro-inflammatory cytokines and increases oxidative stress. The serum uric acid level has emerged as an independent risk factor of cardiovascular disease such as ventricular arrhythmias (VA). Here we had done a systematic review to assess the association between serum UA levels and the occurrence of VA. This systematic review included a total of four clinical studies with 99.383 patients for analysis. The scientific quality of all four studies was good. Three studies showed that serum uric acid levels were associated with VA in many populations. In contrast, one study with a large sample size evaluated that serum uric acid increases premature ventricle contraction prevalence. A significant association between serum uric acid level and VA was found in four studies (p&lt;0.01; p&lt;0.101; p=0.002; p=0.008). In conclusion, this systematic review shows an association between serum UA levels and VA.

Hyperuricemia is associated with an increased prevalence of ventricular tachycardia and fibrillation in patients with ST-elevation myocardial infarction after primary percutaneous coronary intervention

Background

Little is known about the association between hyperuricemia and ventricular tachycardia and fibrillation (VT/VF) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

Methods

The data from a cohort of STEMI patients undergoing PPCI at our center from January 2013 to December 2018 were retrospectively analyzed. The endpoint of the study was the occurrence of VT/VF, including (1) non-sustained ventricular tachycardia (nsVT) on Holter monitoring; (2) sustained ventricular tachycardia (SVT)/VF on cardiac monitoring.

Results

Of the 634 patients included in the study, 147 (23.2%) of them had hyperuricemia. The occurrence of VT/VF after PPCI was significantly higher in patients with hyperuricemia (19.0 vs. 9.4%, p = 0.001) compared with those without hyperuricemia. Hyperuricemia was associated with a significantly higher risk of VF/VT (odds ratio (OR) 2.11; 95% CI 1.11–4.03; p = 0.024). The strength of this association remained statistically after adjustments for age, sex, history of hypertension, estimated glomerular filtration rate, hypersensitive C reactive protein, plasma natrium, peak troponin I, fasting glucose, B-type natriuretic peptides and VT/VF in PPCI (adjusted odds ratio 2.73; 95% CI 1.19–6.27; p = 0.018).

Conclusions

There is a significant association between hyperuricemia and increased prevalence of VT/VF in STEMI patients after PPCI, independently of multiple risk factors and potential confounders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02635-4.

Increased QT Dispersion and High Risk of Ventricular Arrhythmias is Associated with Hyperuricemia in Individuals with Normal Renal Function

Background and aim: Uric acid elevation has been shown to be an important risk factor for cardiovascular and cerebrobascular disease. QT dispersion (QTd) is a parameter that shows the heterogeneity of ventricular repolarization and can be calculated noninvasively from surface electrocardiography. Increased QTd has been associated with severe arrhythmia and risk of sudden death in many patients and disease groups. In this context, we aimed to investigate the effect of uric acid levels on QTd and the effects of decrease in uric acid levels on QTd.

Methods: A total of 225 patients with normal renal function were included in the study; 133 of these patients were hyperuricemic (>7 mg/dL), and the remaining 72 patients were normouricemic (Group 1). The hyperuricemic patients were randomly divided into 2 groups, one group (n = 67) was given placebo (Group 2) for 4 months, and the remaining 66 patients were given allopurinol 300 mg/day (Group 3).

Results: Hyperuricemic patients had higher hsCRP and QTd and lower eGFR values compared to the normouricemic control group. After 4 months of treatment, 66 patients treated with allopurinol showed a significant decrease in serum uric acid, systolic and diastolic blood pressure, and hsCRP levels, and a significant increase in eGFR. Although the QTd values in the treatment group did not decrease to the same levels as in the normouricemic control group, a statistically significant decrease was found compared to their baseline values. In hyperuricemic control and normouricemic control patients, there were no differences in the levels of uric acid, hsCRP, eGFR, systolic and diastolic blood pressure, and QTd values compared to baseline values.

Conclusions: There was a significant association between elevated serum uric acid and QTd, as well as with inflammatory biomarkers. Also, patients who had received hypouricemic therapy during the follow-up period presented a significant decrease in inflammatory markers as well as QTd. This indicates the beneficial effects of decreasing uric acid levels in decreasing the risk for future major adverse events related to ventricular arrhythmias.

Serum uric acid is associated with coronary artery calcification in early chronic kidney disease: a cross-sectional study

Background

Although uric acid (UA) is regarded as a risk factor for cardiovascular disease, whether UA is an independent risk factor contributing to coronary artery calcification in chronic kidney disease (CKD) is not well known. We evaluated whether UA level is associated with coronary artery calcium (CAC) score in a predialysis CKD cohort.

Methods

A total of 1,350 subjects who underwent coronary computed tomography as part of the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease were analysed. We conducted a logistic regression analysis to evaluate the association between UA and the presence of CAC.

Results

CAC was detected in 705 (52.2 %) patients, and the level of UA was significantly higher in CAC > 0 patients. UA showed a positive relationship with CAC > 0 in age- and sex-adjusted logistic regression analysis (Odds ratio (OR) 1.11, 95 % confidence interval (CI) 1.04–1.19, P = 0.003). However, UA showed no association with CAC > 0 in multivariate analysis. Further analysis showed that UA showed a positive association with CAC > 0 only in estimated glomerual filtration rate (eGFR) > 60 ml/min/1.73 m² (OR 1.23, 95 % CI 1.02–1.49, P = 0.036) but not in eGFR 30–59 ml/min/1.73 m² (OR 0.92, 95 % CI 0.78–1.08, P = 0.309) or < 30 ml/min/1.73 m² (OR 0.92, 95 % CI 0.79–1.08, P = 0.426).

Conclusions

UA level was significantly associated with CAC in early CKD, but not in advanced CKD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02463-2.

QT Interval Prolongation in Patients with Systemic Sclerosis-Are the Holter ECG Recordings a Better Option for QT Interval Evaluation?

Background and Objectives: Cardiac involvement in systemic sclerosis has important consequences on patient survival. Myocardial fibrosis and microcirculation involvement can generate arrhythmic complications, which can be associated with a higher death risk. QT interval prolongation is considered as a risk factor for ectopic ventricular events and can be evaluated using standard short ECG recordings or 24-h Holter ECG recordings. Materials and Methods: 39 patients with systemic sclerosis were submitted to a standard ECG recording at admission and 24-h Holter ECG monitoring. Results: QT interval values resulted from Holter ECG monitoring are higher than the values generated by the short-term ECG recordings. Holter ECG monitoring permits the detection of ventricular ectopy in patients with no events on standard ECG. Conclusions: In patients with systemic sclerosis, 24-h Holter ECG recordings can realize a more precise evaluation of the extent of QTc interval prolongation and ventricular ectopic events associated with myocardial involvement.

Laboratory and Instrumental Risk Factors Associated with a Sudden Cardiac Death Prone ECG Pattern in the General Population: Data from the Brisighella Heart Study

Sudden cardiac death (SCD) remains a daunting problem and a major public health issue. We applied the validated Electrocardiogram (ECG) score to the Brisighella Heart Study (BHS) cohort, in order to verify if there were also other recognized laboratory and instrumental risk factors for cardiovascular disease associated with a sudden death risk-prone pattern. We examined the ECG traces of 1377 participants of the 2016 BHS survey and identified 33 subjects at high risk for SCD (while 1344 subjects had no cumulative ECG abnormalities). Serum uric acid (SUA) and carotid-femoral pulse wave velocity (cfPWV) values were significantly higher in the high-risk cohort (p < 0.05) and were both independently associated with the presence of ECG abnormalities [Odd ratio (OR) = 2.14, p < 0.05–OR = 1.23, p < 0.05, respectively]. A similar independent correlation was found with long-term non-steroid anti-inflammatory drugs (NSAIDs) use, more widespread among high-risk subjects (OR = 1.19, p < 0.05). Conversely, the analysis did not show any significant association with impaired renal function (p = 0.09). This study showed that long-term NSAID use and high SUA and cfPWV values are independent risk factors for ECG abnormalities predictive of SCD. These findings herald the need for further prospective research to identify the optimal combination of SCD risk markers in order to prevent fatal events.

Increased Overall Heart Rate Irregularity Risk by Hyperuricemia in the General Population: Results from the Korean National Health and Nutrition Examination Survey

Background and objectives: Hyperuricemia is one of the well-known cardiovascular risk factors. There is a growing interest in the association between hyperuricemia and arrhythmia. We used the representative sample data of Korean population to study the association between hyperuricemia and heart rate irregularity (HRI) that reflects total arrhythmia. Materials and Methods: We performed weighted multivariate logistic regression analysis to assess the association between hyperuricemia and HRI. Results: Of the 10,827 subjects, 1308 (13.2%) had hyperuricemia and 130 (1%) had HRI. In the presence of hyperuricemia, HRI was three times higher than that in the absence of hyperuricemia (OR 2.98, 95% CI 1.71–5.18). The risk of HRI was highest in subjects with both hypertension and hyperuricemia. In the subgroup analysis, the association of hyperuricemia with HRI was most pronounced in the smoker group. Conclusions: Hyperuricemia was highly correlated with HRI in adult Korean representative sample data. Hyperuricemia was associated with a nearly tripled risk for HRI. Hypertension has a synergistic effect with hyperuricemia on HRI. Further research is warranted to clarify the relationship between hyperuricemia and arrhythmia and its mechanism.

Hyperuricemia is a Risk Factor for One-Year Overall Survival in Elderly Female Patients with Acute Coronary Syndrome

Background

Hyperuricemia is a risk factor for cardiovascular diseases, but the impact of hyperuricemia and sex-related disparities is not fully clear in elderly patients with acute coronary syndrome (ACS).

Objective

To investigate the association between hyperuricemia and 1-year all-cause mortality in elderly patients with ACS.

Methods

This retrospective cohort study included 711 consecutive ACS patients aged ≥75 years, hospitalized in our center between January 2013 and December 2017. Serum uric acid (sUA), in-hospital events, and 1-year follow-up were analyzed. Multivariable logistic regression models were used to explore the risk factors for in-hospital events and 1-year all-cause mortality.

Results

sUA levels were higher in males than in females (381.4 ± 110.1 vs. 349.3 ± 119.1 μmol/l, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%,

Conclusions

Hyperuricemia is an independent risk factor for 1-year all-cause mortality in elderly female patients with ACS.

Classic and Novel Biomarkers as Potential Predictors of Ventricular Arrhythmias and Sudden Cardiac Death

Sudden cardiac death (SCD), most often induced by ventricular arrhythmias, is one of the main reasons for cardiovascular-related mortality. While coronary artery disease remains the leading cause of SCD, other pathologies like cardiomyopathies and, especially in the younger population, genetic disorders, are linked to arrhythmia-related mortality. Despite many efforts to enhance the efficiency of risk-stratification strategies, effective tools for risk assessment are still missing. Biomarkers have a major impact on clinical practice in various cardiac pathologies. While classic biomarkers like brain natriuretic peptide (BNP) and troponins are integrated into daily clinical practice, inflammatory biomarkers may also be helpful for risk assessment. Indeed, several trials investigated their application for the prediction of arrhythmic events indicating promising results. Furthermore, in recent years, active research efforts have brought forward an increasingly large number of “novel and alternative” candidate markers of various pathophysiological origins. Investigations of these promising biological compounds have revealed encouraging results when evaluating the prediction of arrhythmic events. To elucidate this issue, we review current literature dealing with this topic. We highlight the potential of “classic” but also “novel” biomarkers as promising tools for arrhythmia prediction, which in the future might be integrated into clinical practice.

Computational models for the prediction of adverse cardiovascular drug reactions

Background

Predicting adverse drug reactions (ADRs) has become very important owing to the huge global health burden and failure of drugs. This indicates a need for prior prediction of probable ADRs in preclinical stages which can improve drug failures and reduce the time and cost of development thus providing efficient and safer therapeutic options for patients. Though several approaches have been put forward for in silico ADR prediction, there is still room for improvement.

Methods

In the present work, we have used machine learning based approach for cardiovascular (CV) ADRs prediction by integrating different features of drugs, biological (drug transporters, targets and enzymes), chemical (substructure fingerprints) and phenotypic (therapeutic indications and other identified ADRs), and their two and three level combinations. To recognize quality and important features, we used minimum redundancy maximum relevance approach while synthetic minority over-sampling technique balancing method was used to introduce a balance in the training sets.

Results

This is a rigorous and comprehensive study which involved the generation of a total of 504 computational models for 36 CV ADRs using two state-of-the-art machine-learning algorithms: random forest and sequential minimization optimization. All the models had an accuracy of around 90% and the biological and chemical features models were more informative as compared to the models generated using chemical features.

Conclusions

The results obtained demonstrated that the predictive models generated in the present study were highly accurate, and the phenotypic information of the drugs played the most important role in drug ADRs prediction. Furthermore, the results also showed that using the proposed method, different drugs properties can be combined to build computational predictive models which can effectively predict potential ADRs during early stages of drug development.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1918-z) contains supplementary material, which is available to authorized users.

Long-term prognostic impact of hyperuricemia in community

The debate whether an elevated level of serum uric acid (SUA) is an independent marker of cardiovascular risk is still going on. We examined morbidity and mortality related to SUA and hyperuricemia in a well-characterized population with very long follow-up. Study included 4696 participants (aged 30-59 years at baseline) of the coronary heart disease (CHD) Study of the Finnish Mobile Clinic Health Examination Survey. Adjusted hazard ratios (HRs) of hyperuricemia (defined as ≥360 µmol/l and ≥420 µmol/l) and SUA quintiles for mortality and adverse cardiovascular outcomes are reported. During the mean follow up of 30.6 years there were 2723 deaths, 887 deaths for CHD of which 340 were classified as sudden cardiac deaths, 1642 hospitalizations due to CHD and 798 hospitalizations due to congestive heart failure. After adjusting to baseline risk factors and presence of cardiovascular diseases as well as the use of diuretics there were no significant differences in the risk of any of the outcomes when analyzed either according to quintiles of SUA or using a cut-off point SUA ≥360 µmol/l for hyperuricemia. Only a rare finding of hyperuricemia SUA ≥420 µmol/l among women (n = 17, 0.9%) was independently associated with significantly higher risk of mortality (adjusted HR: 2.59, 95% CI: 1.54-4.34) and a combination end-point of major adverse cardiac events (MACEs) (HR: 2.69; 95% CI: 1.56-4.66). SUA was not an independent indicator of morbidity and mortality, with the exception of particularly high levels of SUA among women.

Gender-Related Association of Serum Uric Acid Levels with Premature Ventricular Contraction

In this study, we aim to investigate the association of serum uric acid (SUA) with the prevalence of premature ventricular contraction (PVC). The relationship between SUA and the prevalence of PVC in 98,965 subjects (79,034 male subjects, mean age: 51.9 ± 12.6 years old) in the Kailuan cohort study (n = 101,510, age range: 18-98 years) from June 2006 to October 2007 was investigated. These subjects were divided into five groups on the basis of their SUA levels. A multivariate logistic regression model was constructed to evaluate the association between SUA and the prevalence of PVC. The prevalence of PVC was 1.1% in all subjects, 1.1% in male subjects, and 1.0% in female subjects. Compared with the first quintile of SUA, the odds ratio (OR) and 95% confidence interval (95% CI) of other quintiles were 1.33 (1.05-1.69), 1.14 (0.90-1.46), 1.37 (1.08-1.74), and 1.63 (1.30-2.06) in male subjects; 1.12 (0.68-1.87), 1.27 (0.77-2.09), 1.45 (0.90-2.36), and 1.33 (0.81-2.18) in female subjects; and 1.30 (1.04-1.61), 1.20 (0.96-1.50), 1.33 (1.07-1.66), and 1.57 (1.26-1.95) for all subjects. The correlation between SUA and the prevalence of PVC was significant in all subjects and in male subjects, but not in female subjects. We demonstrated that SUA was apparently associated with the prevalence of PVC. The significant relationship between SUA and PVC identified in male subjects suggests the potential involvement of a gender-specific mechanism. Prospective studies are needed to further corroborate our results.

Gout and arrhythmias: In search for causation beyond association

Gout is a systemic disease, characterized by the formation and deposition of crystals in tissues (mainly in and around the joints) of individuals with elevated serum uric acid levels. Lately, a considerable number of reports relating elevated uric acid and/or gout with rhythm disorders, such as atrial fibrillation, have been published. This review summarizes evidence linking common arrhythmias and hyperuricemia/gout and discusses questions or controversies that surround it. Overall, existing evidence may not be overwhelming, but strongly suggests a positive correlation between uric acid levels and common rhythm disorders. Needless to say that such a link - as a univariate association between the two - is to be expected, given the extensive overlap of risk factors and comorbidities of hyperuricemia/gout and arrhythmias. However, the observed associations seem to persist - in most studies - after extensive adjustment for potential confounders. Still, multivariable analyses of epidemiologically collected data cannot substitute for proof coming from basic and clinical studies. There is obviously a need for further basic research to establish a causal relationship between uric acid effects and arrhythmias, as well as translational studies and clinical trials to investigate the therapeutic implications of such a relationship. Simply put, we are fairly certain that there is association, but proof of causation is what we are still in want of.

Uric acid and cardiovascular risk: What genes can say

BACKGROUND

Although the relationship of elevated serum uric acid levels and cardiovascular disease has been established in a great number of studies, the causal relevance of this finding remains ambiguous. An approach to evaluate the causal relevance of biomarkers is to exploit the natural randomised allocation of allelic variation in genes affecting their level, also known as Mendelian randomisation.

AIM

The aim of this paper is to review the current literature regarding serum uric acid levels and cardiovascular and renal disease risk in Mendelian randomisation studies.

METHODS

PubMed and Scopus databases were searched to retrieve Mendelian studies regarding uric acid, hyperuricaemia and cardiovascular risk.

CONCLUSIONS

Genetic evidence based on conventional and novel Mendelian randomisation approaches suggest a modest, if any, causal effect of serum uric acid concentration on the development of cardiovascular disease, suggesting that further study of uric acid genes is needed in order to elucidate the relationship of serum uric acid levels and cardiovascular disease.

Sex-specific association between serum uric acid and prolonged corrected QT interval: Result from a general rural Chinese population

Recently, it has been found that high level of serum uric acid (SUA) is causally related to sudden cardiac death (SCD). We examined the sex-specific associations of SUA with prolonged heart rate-corrected QT (QTc) interval in a general Chinese population.A large sample of 11,206 Chinese research participants aged 35 years and older was recruited from rural areas of Liaoning Province during 2012 to 2013. SUA were divided into quartiles separated for males and females. Prolonged QTc interval, assessed by the Bazett formula, was defined as cut points of 460 ms or longer in females and 450 ms or longer in males. Mean (+/- standard deviation) QTc intervals were 422.1 ± 24.2 ms among 5104 males and 436.1 ± 23.5 ms among 6102 females, respectively. In both sexes, SUA showed significant correlations with QTc interval (both P < 0.001). Among male participants, the highest quartile of SUA (>379 μmol/L) was related to an increased risk for prolonged QTc interval (odds ratios: 1.402, 95% confidence interval: 1.073-1.831) compared to the lowest quartile (≤276 μmol/L) after fully adjustment. However, there were no significant relationships between SUA and prolonged QTc interval among females in all the models.Males with high SUA are prone to a higher risk for prolonged QTc interval. This study provides novel explanation for population-based findings on SUA and SCD, as well as important implications for management strategies for hyperuricemic patients in clinical practice.

Effects of urate-lowering agents on arrhythmia vulnerability in post-infarcted rat hearts

Hyperuricemia has been shown to be associated with ventricular arrhythmias. However, the mechanisms remained unknown. We assessed whether different urate-lowering agents can attenuate arrhythmias through lowering urate itself or inhibiting xanthenes oxidize (XO) activity in infarcted rats. Male Wistar rats after ligating coronary artery were randomized to either allopurinol, or febuxostat, chemically unrelated inhibitors of XO, benzbromarone or vehicle for 4 weeks. Post-infarction was associated with increased oxidant stress, as measured by myocardial superoxide, isoprostane, XO activity and dihydroethidine fluorescence staining. Measurement of myocardial norepinephrine levels revealed a significant elevation in vehicle-treated infarcted rats compared with sham-operated rats. Sympathetic hyperinnervation was blunted after administering both XO inhibitors, assessed by immunofluorescent analysis, Western blotting and real-time quantitative RT-PCR. Besides, the XO inhibitors-attenuated nerve growth factor levels were reversed in the presence of peroxynitrite generator. Arrhythmic scores in the XO inhibitors-treated infarcted rats were significantly lower than that in vehicle. For similar levels of urate lowering, the uricosuric agent benzbromarone had no beneficial effects on oxidative stress, sympathetic hyperinnervation or arrhythmia vulnerability. Chronic use of XO inhibitors, but not uricosuric agent, down-regulated sympathetic innervation probably through a superoxide-dependent pathway and plays a role in the beneficial effect on arrhythmogenic response.

Uric Acid and Cardiovascular Events: A Mendelian Randomization Study

Obesity and diets rich in uric acid-raising components appear to account for the increased prevalence of hyperuricemia in Westernized populations. Prevalence rates of hypertension, diabetes mellitus, CKD, and cardiovascular disease are also increasing. We used Mendelian randomization to examine whether uric acid is an independent and causal cardiovascular risk factor. Serum uric acid was measured in 3315 patients of the Ludwigshafen Risk and Cardiovascular Health Study. We calculated a weighted genetic risk score (GRS) for uric acid concentration based on eight uric acid-regulating single nucleotide polymorphisms. Causal odds ratios and causal hazard ratios (HRs) were calculated using a two-stage regression estimate with the GRS as the instrumental variable to examine associations with cardiometabolic phenotypes (cross-sectional) and mortality (prospectively) by logistic regression and Cox regression, respectively. Our GRS was not consistently associated with any biochemical marker except for uric acid, arguing against pleiotropy. Uric acid was associated with a range of prevalent diseases, including coronary artery disease. Uric acid and the GRS were both associated with cardiovascular death and sudden cardiac death. In a multivariate model adjusted for factors including medication, causal HRs corresponding to each 1-mg/dl increase in genetically predicted uric acid concentration were significant for cardiovascular death (HR, 1.77; 95% confidence interval, 1.12 to 2.81) and sudden cardiac death (HR, 2.41; 95% confidence interval, 1.16 to 5.00). These results suggest that high uric acid is causally related to adverse cardiovascular outcomes, especially sudden cardiac death.