Uric acid and hypertension

Management of hypertension addressing hyperuricaemia: introduction of nano-based approaches

Uric acid (UA) levels in blood serum have been associated with hypertension, indicating a potential causal relationship between high serum UA levels and the progression of hypertension. Therefore, the reduction of serum UA level is considered a potential strategy for lowering and mitigating blood pressure. If an individual is at risk of developing or already manifesting elevated blood pressure, this intervention could be an integral part of a comprehensive treatment plan. By addressing hyperuricaemia, practitioners may subsidize the optimization of blood pressure regulation, which illustrates the importance of addressing UA levels as a valuable strategy within the broader context of hypertension management. In this analysis, we outlined the operational principles of effective xanthine oxidase inhibitors for the treatment of hyperuricaemia and hypertension, along with an exploration of the contribution of nanotechnology to this field.

Hyperuricemia and its related diseases: mechanisms and advances in therapy

Hyperuricemia, characterized by elevated levels of serum uric acid (SUA), is linked to a spectrum of commodities such as gout, cardiovascular diseases, renal disorders, metabolic syndrome, and diabetes, etc. Significantly impairing the quality of life for those affected, the prevalence of hyperuricemia is an upward trend globally, especially in most developed countries. UA possesses a multifaceted role, such as antioxidant, pro-oxidative, pro-inflammatory, nitric oxide modulating, anti-aging, and immune effects, which are significant in both physiological and pathological contexts. The equilibrium of circulating urate levels hinges on the interplay between production and excretion, a delicate balance orchestrated by urate transporter functions across various epithelial tissues and cell types. While existing research has identified hyperuricemia involvement in numerous biological processes and signaling pathways, the precise mechanisms connecting elevated UA levels to disease etiology remain to be fully elucidated. In addition, the influence of genetic susceptibilities and environmental determinants on hyperuricemia calls for a detailed and nuanced examination. This review compiles data from global epidemiological studies and clinical practices, exploring the physiological processes and the genetic foundations of urate transporters in depth. Furthermore, we uncover the complex mechanisms by which the UA induced inflammation influences metabolic processes in individuals with hyperuricemia and the association with its relative disease, offering a foundation for innovative therapeutic approaches and advanced pharmacological strategies.

Uric acid and cardiovascular diseases: a reappraisal

Serum uric acid (SUA) has garnered an increased interest in recent years as an important determinant of cardiovascular disease. Uric acid, a degradation product of purine metabolism, is affected by several inheritable and acquired factors, such as genetic mutation, metabolic syndrome, chronic kidney disease, and medication interactions. Even though elevated SUA have been commonly associated with the development of gout, it has significant impact in the development of hypertension, metabolic syndrome, and cardiovascular disease. Uric acid, in both crystalline and soluble forms, plays a key role in the induction of inflammatory cascade and development of atherosclerotic diseases. This concise reappraisal emphasizes key features about the complex and challenging role of uric acid in the development and progression of atherosclerosis and cardiovascular disease. It explores the pathogenesis and historical significance of uric acid, highlights the complex interplay between uric acid and components of metabolic syndrome, focuses on the pro-inflammatory and pro-atherogenic effects of uric acid, as well as discusses the role of urate lowering therapies in mitigating the risk of cardiovascular disease while providing the latest evidence to the healthcare professionals focusing on the clinical importance of SUA levels with regards to cardiovascular disease.

Hyperuricemia - consequences of not initiating therapy. Benefits and drawbacks of treatment

Hyperuricemia, characterized by elevated levels of uric acid in the body, is associated with several health risks, including gout, urolithiasis and cardiovascular disease. Although treatment options are available, they can lead to hypersensitivity reactions, particularly with allopurinol therapy. This paper provides a comprehensive review of the consequences of hyperuricemia, the need for treatment and the potential adverse effects of allopurinol, illustrated by a case study. The study highlights the importance of careful consideration before initiating therapy, particularly in patients with comorbidities and concomitant medication. It emphasizes the need for vigilant monitoring and individualized treatment approaches to reduce adverse effects. In addition, genetic factors, particularly HLA-B*5801, play an important role in determining susceptibility to allopurinol hypersensitivity reactions. This paper highlights the importance of informed decision making in the management of hyperuricemia to optimize patient outcomes while minimizing the risks associated with treatment.

Association between serum uric acid levels and dietary fiber intake in adults: the Korea national health and nutrition examination survey (KNHANES VII, 2016-2018)

BACKGROUND

Hyperuricemia could be a risk for various chronic diseases, and it could be largely corrected by diet control. This study was a nationwide cross-sectional study to investigate the association between serum uric acid level and dietary fiber intake.

METHODS

This study analyzed data based on the Korean National Health and Nutrition Examination Survey conducted from 2016 to 2018. Adults over 20 years of age with normal renal function, defined as an estimated glomerular filtration rate (eGFR) over 30mL/min/1.73m2, were included. The criteria for hyperuricemia were ≥ 7 mg/dL in men and ≥ 6 mg/dL in women. Data regarding dietary intake were obtained using the 24-hour recall method.

RESULTS

A total of 15,278 subjects (6,455 males/8,823 females) were analyzed. The prevalence of hyperuricemia was 19.3% in men and 6.8% in women. There were significant, negative associations between serum uric acid and total fiber intake in both men and women. Consuming more than 27.9 g of dietary fiber in men and 20.7 g in women reduced the risk of hyperuricemia by approximately 30% with odds ratios of 0.72 (0.62-0.83) and 0.71 (0.56-0.88) in men and women, respectively. With regard to the risk reduction by the type of dietary fiber, cereal fiber was significantly identified in both men and women, while fruit fiber was only significant in men. In the subgroup analysis, this association remained significantly in young and metabolically healthy populations with normal weight.

CONCLUSIONS

Dietary fiber intake was inversely associated with serum uric acid levels. This relationship was particularly significant in metabolically healthy young adults.

Sex-specific associations between serum uric acid levels and risk of hypertension for different diagnostic reference values of high blood pressure

The association between uric acid (UA) and hyperuricemia with 5-year hypertension incidence using different blood pressure (BP) diagnostic references in men and women without cardiometabolic diseases is unknown. We used the checkup data from Kagoshima Kouseiren Hospital. All participants with hypertension or on BP medication, diabetes, dyslipidemia, obesity, estimated glomerular filtration rate<60 ml/min/1.73m2, metabolic syndrome, history of gout, and UA-lowering medication were excluded. UA was categorized into sex-specific quartiles and hyperuricemia was defined as UA > 7 mg/dl in men and UA > 6 mg/dl in women. We performed multivariate logistic regression to assess the effects of UA on hypertension development. The 5-year hypertension incidence was defined as subsets of BP ≥ 140/90 mmHg in cohort 1 and BP ≥ 130/80 mmHg in cohort 2. The study enrolled 21,443 participants (39.8%, men) in cohort 1 and 15,245 participants (36.5%, men) in cohort 2. The incidence of hypertension in cohorts 1 and 2 over 5 years was 16.3% and 29.7% in men and 10.9% and 21.4% in women, respectively. When comparing the fourth to the first UA quartile, there was an association with hypertension in men in cohort 1, with odds ratio (OR): 1.36 (95% confidence interval [CI], 1.13-1.63, p < 0.01) and cohort 2, OR: 1.31 (95%CI, 1.09-1.57, p < 0.01), respectively, but not in women. Additionally, an association between hyperuricemia and hypertension was observed in men only in cohort 1, with OR: 1.23 (95%CI, 1.07-1.42, p = 0.02), and in women in cohort 2, OR: 1.57 (95%CI, 1.14-2.16, p < 0.01). The effect of UA on the development of hypertension is influenced by sex and incidence differs with the BP reference used. Uric acid effect on the development of hypertension is affected by sex and incidence differs with the BP reference used.

Effect of ketogenic diet on blood pressure: A GRADE-Assessed systematic review and meta-analysis of randomized controlled trials

AIMS

Cardiovascular diseases (CVDs) are major causes of mortality around the world. High blood pressure (BP) or hypertension is one of the most significant predisposing factors to CVDs. Ketogenic diets (KDs) have been the center of attention for their possible health benefits. The aim of this analysis is to study the impact of KDs on BP through the existing literature.

DATA SYNTHESIS

We investigated the impact of KDs on systolic and diastolic blood pressures (SBP and DBP) conducted in the format of randomized controlled trials (RCTs). Four online databases (PubMed/Medline, SCOPUS, Cochrane Library, and Google Scholar) were searched from inception up to November 2022. Subgroup analyses were carried out to find the sources of heterogeneities. Twenty-three RCTs with 1664 participants were identified. KDs did not exert any significant impacts on SBP (WMD: -0.87 mmHg, 95% CI: -2.05, 0.31) nor DBP (WMD: -0.11 mmHg, 95% CI -1.14, 0.93). Subgroup analyses did not reveal any further information. Also, non-linear dose-response analysis could not detect any associations between the percentage of calorie intake from fat in the KD format and BP levels.

CONCLUSION

KDs do not seem to be effective in improving BP. Nonetheless, further investigations are recommended to examine the proportion of fat intake needed to induce favorable clinical impacts.

Hard Magnetic Graphene Nanocomposite for Multimodal, Reconfigurable Soft Electronics

Soft electronics provide effective means for continuous monitoring of a diverse set of biophysical and biochemical signals from the human body. However, the sensitivities, functions, spatial distributions, and many other features of such sensors remain fixed after deployment and cannot be adjusted on demand. Here, laser-induced porous graphene is exploited as the sensing material, and dope it with permanent magnetic particles to create hard magnetic graphene nanocomposite (HMGN) that can self-assemble onto a flexible carrying substrate through magnetic force, in a reversible and reconfigurable manner. A set of soft electronics in HMGN exhibits enhanced performances in the measurements of electrophysiological signals, temperature, and concentrations of metabolites. All these flexible HMGN sensors can adhere to a carrying substrate at any position and in any spatial arrangement, to allow for wearable sensing with customizable sensitivity, modality, and spatial coverage. The HMGN represents a promising material for constructing soft electronics that can be reconfigured for various applications.

Association between serum uric acid and bone mineral density in males from NHANES 2011-2020

Currently, the relationship between serum uric acid (SUA) and bone mineral density (BMD) in men remains controversial. This study aims to investigate the relationship between SUA and lumbar spine BMD in American men using data from the National Health and Nutrition Examination Survey (NHANES). A total of 6254 male subjects aged 12-80 years (mean age 35.52 ± 14.84 years) in the NHANES from 2011 to 2020 were analyzed. SUA was measured by DxC using the timed endpoint method, and lumbar spine BMD was measured by dual-energy X-ray absorptiometry (DXA). Multivariate linear regression models were used to explore the relationship between SUA and BMD by adjusting for age, race/Hispanic origin, drinking behavior, smoking behavior, physical activity, body mass index (BMI), poverty-to-income ratio (PIR), total protein, serum calcium, cholesterol, serum phosphorus, and blood urea nitrogen. After correcting for the above confounders, it was found that SUA was positively associated with lumbar spine BMD in the range of SUA < 5 mg/dL (β = 0.006 95% CI 0.003-0.009, P < 0.001), and BMD of individuals in the highest quartile of SUA was 0.020 g/cm2 higher than those in the lowest quartile of SUA (β = 0.020 95% CI 0.008-0.032, P = 0.003). This study showed that SUA was positively correlated with lumbar spine BMD in American men within a certain range. This gives clinicians some insight into how to monitor SUA levels to predict BMD levels during adolescence when bone is urgently needed for growth and development and during old age when bone loss is rapid.

Gender Influence on XOR Activities and Related Pathologies: A Narrative Review

Taking into account the patient's gender is the first step towards more precise and egalitarian medicine. The gender-related divergences observed in purine catabolism and their pathological consequences are good examples of gender medicine differences. Uric acid is produced by the activity of xanthine oxidoreductase (XOR). The serum levels of both XOR activity and uric acid differ physiologically between the genders, being higher in men than in women. Their higher levels have been associated with gout and hypertension, as well as with vascular, cardiac, renal, and metabolic diseases. The present review analyzes the gender-related differences in these pathological conditions in relation to increases in the serum levels of XOR and/or uric acid and the opportunity for gender-driven pharmacological treatment.

The effect of low-fructose diet on anthropometric and metabolic factors: A systematic review and meta-analysis

AIMS

In recent decades, there has been a rise in the consumption of sugars containing fructose, raising concerns about their association with metabolic disorders and obesity. We conducted a systematic review and meta-analysis of randomized controlled trials to assess the effects of a low-fructose diet on anthropometric and metabolic variables.

DATA SYNTHESIS

We conducted a systematic review and meta-analysis of randomized controlled trials to assess the effects of low-fructose diets on anthropometric and metabolic factors. Relevant studies were identified by searching electronic databases such as PubMed, Scopus, and Web of Science up to January 2023. The quality of the included studies was assessed using the Cochrane risk-of-bias tool. Ten trials with varying intervention durations (ranging from 4 to 24 weeks) and a total of 750 participants were included. The analysis revealed that a low-fructose diet had no significant effect on weight but did have a significant impact on body mass index (SMD = -0.2; 95 % CI: -0.37, -0.04, P = 0.017) and waist circumference (SMD = -0.48; 95 % CI: -0.67, -0.29, P < 0.0001). Furthermore, a low-fructose diet significantly affected systolic blood pressure (SMD = -0.24; 95 % CI: -0.39, -0.09, P = 0.002), fasting blood glucose (SMD = -0.23; 95 % CI: -0.40, -0.07, P = 0.005), hemoglobin A1c (SMD = -0.62; 95 % CI: -0.93, -0.31, P < 0.0001), and triglyceride levels (SMD = -0.17; 95 % CI: -0.33, -0.02, P = 0.028). However, it had no significant effect on diastolic blood pressure, insulin levels, or homeostatic model assessment of insulin resistance. Subgroup analysis indicated that a low-fructose diet had a greater effect on healthy participants aged over 50 years.

CONCLUSIONS

Meta-analysis results suggest that low-fructose diets significantly reduce body mass index, waist circumference, systolic blood pressure, fasting blood glucose, hemoglobin A1c, and triglyceride levels. Additionally, the results of the current study suggest that a low-fructose diet may be more effective in healthy individuals who are older than 50 years old compared to those younger than 50 years old.

Machine Learning Insights Into Uric Acid Elevation With Thiazide Therapy Commencement and Intensification

Background Elevated serum uric acid, associated with cardiovascular conditions such as atherosclerotic heart disease, hypertension, and heart failure, can be elevated by thiazide or thiazide-like drugs (THZ), essential in hypertension management. Identifying clinical determinants affecting THZ-related uric acid elevation is critical. Methods In this retrospective cross-sectional study, we explored the clinical determinants influencing uric acid elevation related to THZ, focusing on patients where THZ was initiated or the dose escalated. A cohort of 143 patients was analyzed, collecting baseline and control uric acid levels, alongside basic biochemical studies and clinical data. Feature selection was conducted utilizing criteria based on mean squared error increase and enhancement in node purity. Four machine learning algorithms - Random Forest, Neural Network, Support Vector Machine, and Gradient Boosting regressions - were applied to pinpoint clinical influencers. Results Significant features include uncontrolled diabetes, index estimated Glomerular Filtration Rate (eGFR) level, absence of insulin, action of indapamide, and absence of statin treatment, with absence of Sodium-glucose cotransporter 2 inhibitors (SGLT2i), low dose aspirin exposure, and older age also being noteworthy. Among the applied models, the Gradient Boosting regression model outperformed the others, exhibiting the lowest Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Squared Error (RMSE) values, and the highest R2 value (0.779). While Random Forest and Neural Network regression models were able to fit the data adequately, the Support Vector Machine demonstrated inferior metrics. Conclusions Machine learning algorithms are adept at accurately identifying the factors linked to uric acid fluctuations caused by THZ. This proficiency aids in customizing treatments more effectively, reducing the need to unnecessarily avoid THZ, and providing guidance on its use to prevent instances where uric acid levels could become problematic.

Target Screen of Anti-Hyperuricemia Compounds from Cortex Fraxini In Vivo Based on ABCG2 and Bioaffinity Ultrafiltration Mass Spectrometry

The ATP-binding cassette (ABC) transporter ABCG2 is a significant urate transporter with a high capacity, and it plays a crucial role in the development of hyperuricemia and gout. Therefore, it has the potential to be targeted for therapeutic interventions. Cortex Fraxini, a traditional Chinese medicine (TCM), has been found to possess anti-hyperuricemia properties. However, the specific constituents of Cortex Fraxini responsible for this effect are still unknown, particularly the compound that is responsible for reducing uric acid levels in vivo. In this study, we propose a target screening protocol utilizing bio-affinity ultrafiltration mass spectrometry (BA-UF-MS) to expediently ascertain ABCG2 ligands from the plasma of rats administered with Cortex Fraxini. Our screening protocol successfully identified fraxin as a potential ligand that interacts with ABCG2 when it functions as the target protein. Subsequent investigations substantiated fraxin as an activated ligand of ABCG2. These findings imply that fraxin exhibits promise as a drug candidate for the treatment of hyperuricemia. Furthermore, the utilization of BA-UF-MS demonstrates its efficacy as a valuable methodology for identifying hit compounds that exhibit binding affinity towards ABCG2 within TCMs.

Mechanisms and rationale for uricase use in patients with gout

Xanthine oxidase inhibitors such as allopurinol and febuxostat have been the mainstay urate-lowering therapy (ULT) for treating hyperuricaemia in patients with gout. However, not all patients receiving oral ULT achieve the target serum urate level, in part because some patients cannot tolerate, or have actual or misconceived contraindications to, their use, mainly due to comorbidities. ULT dosage is also limited by formularies and clinical inertia. This failure to sufficiently lower serum urate levels can lead to difficult-to-treat or uncontrolled gout, usually due to poorly managed and/or under-treated gout. In species other than humans, uricase (urate oxidase) converts urate to allantoin, which is more soluble in urine than uric acid. Exogenic uricases are an exciting therapeutic option for patients with gout. They can be viewed as enzyme replacement therapy. Uricases are being used to treat uncontrolled gout, and can achieve rapid reduction of hyperuricaemia, dramatic resolution of tophi, decreased chronic joint pain and improved quality of life. Availability, cost and uricase immunogenicity have limited their use. Uricases could become a leading choice in severe and difficult-to-treat gout as induction and/or debulking therapy (that is, for lowering of the urate pool) to be followed by chronic oral ULT. This Review summarizes the evidence regarding available uricases and those in the pipeline, their debulking effect and their outcomes related to gout and beyond.

Exploring the Effects of Elevated Serum Uric Acid Levels on Hypertension: A Scoping Review of Hyperuricemia

Hypertension (HTN) is a global health concern due to its increasing prevalence and association with life-threatening complications. An intriguing area of investigation in HTN research is the relationship between HTN and hyperuricemia. In light of this, we conducted a review to summarize the relevant studies exploring the link between elevated serum uric acid (sUA) concentration and new-onset HTN. Through a comprehensive search of PubMed Central, MEDLINE, and PubMed databases, we identified 20 studies that met our inclusion criteria. The research encompassed various study designs, including cohort studies, cross-sectional studies, reviews, and clinical trials. Pathologically, the elevated sUA levels activate the renin-angiotensin system and also cause the formation of urate crystals, triggering inflammation in the kidneys. Additionally, direct effects on the endothelium contribute to inflammation, oxidative stress, nitric oxide depletion, and smooth muscle cell proliferation, ultimately leading to atherosclerosis. These diverse mechanisms collectively play a role in the pathogenesis of HTN. Interestingly, lowering sUA has been shown to reverse early-stage HTN dependent on uric acid. However, this effect is not observed in the uric acid-independent second stage of HTN. Various studies have demonstrated an independent and dose-dependent association between sUA levels and the prevalence of HTN across different populations and genders. The review highlights the potential role of uric acid-lowering drugs, like allopurinol, in the prevention and early-stage management of HTN. However, there is scarce research on the efficacy of other uric acid-lowering agents and combination therapies. We believe our review provides compelling evidence of the association between elevated sUA concentration and new-onset HTN. Identifying and managing hyperuricemia can provide a preventive approach to reducing the burden of HTN and its associated complications.

Update in uric acid, hypertension, and cardiovascular diseases

A direct relationship between serum uric acid levels and hypertension, cardiovascular, renal and metabolic diseases has been reported in many basic and epidemiological studies. Among these, high blood pression is one of the most common features associated with hyperuricemia. In this regard, several small-scale interventional studies have demonstrated a significant reduction in blood pressure in hypertensive or prehypertensive patients on uric acid-lowering drugs. These observation or intervention studies have led to affirm that there is a causal relationship between uric acid and hypertension. While the clinical association between uric acid and high blood pressure is notable, no clear conclusion has yet been reached as to whether lowering uric acid is beneficial to prevent cardiovascular and renal metabolic diseases. Recently, several prospective randomized controlled intervention trials using allopurinol and other uric acid-lowering drugs have been reported, and the results from these trials were almost negative, suggesting that the correlation between hyperuricemia and cardiovascular disease has no causality. However, it is important to note that in some of these recent studies there were high dropout rates and an important fraction of participants were not hyperuricemic. Therefore, we should carry caution in interpreting the results of these studies. This review article presents the results of recent clinical trials using uric acid-lowering drugs, focusing on hypertension and cardiovascular and renal metabolic diseases, and discusses the future of uric acid therapy.

The effect of dietary approaches to stop hypertension and ketogenic diets intervention on serum uric acid concentration: a systematic review and meta-analysis of randomized controlled trials

Hyperuricemia as a risk factor for metabolic diseases is proved to be profoundly modified by dietary approaches. This systematic review and meta-analysis of randomized control trials (RCT) was conducted to investigate the effect of two nutritional interventions; dietary approaches to stop hypertension (DASH) diet and ketogenic diet (KD) on serum uric acid (UA) concentrations. Our systematic search was for RCTs in which KD or DASH diet were assigned to adults for at least 2 weeks or more. Until March 2023 in Embase, Web of Science, PubMed, and Scopus databases, 10 eligible RCTs that intervened with DASH diet (n = 4) or KD (n = 6) and had provided laboratory data on serum UA were found. Summary effect was calculated by random-effects model. Results from the meta-analysis of the 4 DASH diet RCTs with a total of 590 participants revealed significant decrease in serum UA after at least 4 weeks of interventions (mean difference (MD) = ‒0.25; 95% CI ‒0.4 to ‒0.1 mg/dL; p < 0.01; I² = 0%). The pooled meta-analysis of the 6 included RCTs of KD reporting data of 267 participants showed no significant changes in serum UA (MD = 0.26; 95% CI ‒0.47 to 0.98 mg/dL, I² = 95.32%). However, a non-significant reduction of UA in the subgroup analysis of very low-calorie KD (VLCKD) studies (MD = ‒0.04; 95% CI ‒0.29 to 0.22, I² = 0%) was obtained. DASH diet has an ameliorating effect on serum UA and may be recommended for hyperuricemia states such as gout. In addition, we have shown that serum UA level following KD remained unchanged. Although, in view of the heterogeneity across the studies, further investigations are needed to determine the effect of KD and VLKD on serum UA concentrations.

A new application of papain: As a peroxidase-like catalyst for fluorometric detection of uric acid

Papain, as a classical cysteine protease, has been widely used in the food, pharmaceutical, chemical, and cosmetic fields. However, there are few information about the peroxidase-like activity of papain catalyzed substrate to produce fluorescence. In this study, we found that papain can catalyze H₂O₂ to convert o-phenylenediamine (OPD), and generate fluorescence emission at 550 nm under 430 nm excitation. Based on this foundation, we report a papain/OPD/H₂O₂ system for fluorescence detection of uric acid. The method exhibits a wide linear range of 10-1000 μM with a limit-of-detection of 4.6 μM, and has been successfully used to detect uric acid in human serum. This study paves the way for the application of papain as catalyst for fluorescence detection of different target biomolecules, such as cholesterol, glucose, lactate, for which H₂O₂ is a product of oxidoreductase enzymes.

The Effects of Topiroxostat, a Selective Xanthine Oxidoreductase Inhibitor, on Arterial Stiffness in Hyperuricemic Patients with Liver Dysfunction: A Sub-Analysis of the BEYOND-UA Study

Background: The effects of uric acid (UA)-lowering therapy with xanthine oxidoreductase (XOR) inhibitors on the development of cardiovascular diseases remain controversial. Based on recent findings that plasma XOR activity increased in liver disease conditions, we conducted a sub-analysis of the BEYOND-UA study to examine the differential effects of topiroxostat on arterial stiffness based on liver function in hyperuricemic individuals with hypertension. Methods: Sixty-three subjects treated with topiroxostat were grouped according to baseline alanine aminotransferase (ALT) levels (above or below cut-off values of 22, 30, or 40 U/L). The primary endpoint was changes in the cardio-ankle vascular index (CAVI) from baseline to 24 weeks. Results: Significant reductions in CAVI during topiroxostat therapy occurred in subjects with baseline ALT ≥30 U/L or ≥40 U/L, and significant between-group differences were detected. Brachial-ankle pulse wave velocity significantly decreased in the ALT-high groups at all cut-off values. Reductions in morning home blood pressure and serum UA were similar regardless of the baseline ALT level. For eleven subjects with available data, ALT-high groups showed high plasma XOR activity, which was significantly suppressed by topiroxostat. Conclusions: Topiroxostat improved arterial stiffness parameters in hyperuricemic patients with liver dysfunction, which might be related to its inhibitory effect on plasma XOR.

High-Fructose Diet-Induced Hyperuricemia Accompanying Metabolic Syndrome-Mechanisms and Dietary Therapy Proposals

Fructose is often used as a food ingredient due to its low production costs and sweetening power. In recent years, it has been noticed that people on a Western diet high in fructose have high levels of uric acid in their blood. It was recognized that the specific metabolism of fructose in the body might cause increased production of uric acid, which then may affect the intensification of lipogenesis and the development of metabolic syndrome (MetS), insulin resistance, gout, cardiovascular diseases, leptin resistance, or non-alcoholic fatty liver disease. So far, to treat hyperuricemia, it has been recommended to use a low-purine diet characterized by limiting protein-containing products. However, this recommendation often leads to an increased intake of carbohydrate-rich foods that may contain fructose. Increased fructose consumption may enhance the secretion of uric acid again and, consequently, does not have therapeutic effects. Therefore, instead of a low-purine diet, using healthy diets, such as DASH or the Mediterranean diet, which can benefit metabolic parameters, could be a better proposal. This article provides an overview of this approach, focusing on MetS and hyperuricemia among high-fructose dieters.

Effect of Topiroxostat on Reducing Oxidative Stress in the Aorta of Streptozotocin-Induced Diabetic Rats

Xanthine oxidoreductase exists both intracellularly and extracellularly and induces vascular injury by producing reactive oxygen species (ROS). Here, we investigated the effects and mechanism of action of topiroxostat, a xanthine oxidase inhibitor, on ROS using an animal model of type 1 diabetes with persistent hyperglycemia. Six-week-old male Sprague-Dawley rats were administered 50 mg/kg streptozotocin to induce diabetes; at 8 weeks of age, animals were administered topiroxostat (0.3, 1, or 3 mg/kg) for 2 weeks through mixed feeding after which the aorta was sampled. The production of superoxide, a type of ROS, was measured by chemiluminescence and dihydroethidium staining. Cytotoxicity was evaluated by nitrotyrosine staining. Topiroxostat at 3 mg/kg significantly decreased blood urea nitrogen, e-selectin, urinary malondialdehyde, and the urinary albumin/creatinine ratio compared with the streptozotocin group. Superoxide production by xanthine oxidase anchored to the cell membrane was significantly decreased by topiroxostat at both 1 mg/kg and 3 mg/kg compared with the streptozotocin group. Dihydroethidium staining revealed no significant effect of topiroxostat administration on superoxide production. The fluorescence intensity of nitrotyrosine staining was significantly suppressed by 3 mg/kg topiroxostat. Topiroxostat was found to inhibit the production of ROS in the thoracic aorta and suppress vascular endothelial damage. The antioxidant effect of topiroxostat appears to be exerted via the inhibition of anchored xanthine oxidase.

Association of serum uric acid with benefits of intensive blood pressure control

INTRODUCTION AND OBJECTIVES

Intensive systolic blood pressure (SBP) control improved outcomes in the Strategy of Blood Pressure Intervention in the Elderly Hypertensive Patients (STEP) trial. Whether the serum uric acid concentration at baseline alters the benefits of intensive SBP control is unknown.

METHODS

The STEP trial was a randomized controlled trial that compared the effects of intensive (SBP target of 110 to<130mmHg) and standard (SBP target of 130 to <150mmHg) SBP control in Chinese patients aged 60 to 80 years with hypertension. The primary outcome was a composite of cardiovascular disease events. This post hoc analysis was performed to examine whether the effects of intensive SBP intervention differed by the baseline uric acid concentration using 2 models: restricted cubic spline curves and subgroup analyses, both based on the Fine-Gray subdistribution hazard model in the analysis of the primary outcome and secondary outcomes (excluding all-cause death). In the analysis of all-cause death, the Cox regression model was used. We also examined the change in the follow-up uric acid concentrations.

RESULTS

Overall, the risk of the primary outcome rose as the cumulative uric acid concentration increased in both the intensive and standard treatment groups. Patients with intensive treatment had a lower multivariable-adjusted subdistribution hazard ratio for the primary outcome, but with a wide overlap of 95%CI. Next, we stratified patients according to their baseline uric acid concentration (tertile 1 [T1], <303.0μmol/L; tertile 2 [T2], 303.0 to <375.8μmol/L; and tertile 3 [T3], ≥375.8μmol/L). Subgroup analyses using tertiles provided HRs and 95%CI in T1 (HR, 0.55; 95%CI, 0.36-0.86; P=.008), T2 (HR, 0.80; 95%CI, 0.56-1.14; P=.22) and T3 (HR, 0.86; 95%CI, 0.60-1.21; P=.39), with an interaction P value of .29. The results for most of the secondary outcomes followed the same trends.

CONCLUSIONS

There was no evidence that the benefit of the intensive SBP control differed by baseline uric acid concentrations. This trial was registered at ClinicalTrial.gov (Identifier: NCT03015311).

Salivary uric acid reactivity and baseline associations with physiological stress response

Uric acid, an end product of the purinergic system, plays a role in several physiological systems that are responsive to stress. However, few studies have examined whether (1) uric acid concentrations change in response to acute stress, and (2) there are cross-system associations where uric acid might influence other physiological system responses to acute physical stress. The present study measured indices of the purinergic, hypothalamic-pituitary-adrenal axis, sympathetic, and parasympathetic systems (uric acid, cortisol, pre-ejection period, and root mean square of successive differences, respectively) in response to a standardized acute physical pain stressor, the cold pressor task. A diverse sample of participants (n = 67; mean age = 20.5 years, 52% female; 48% male) from a larger study completed anthropometric measurements and took part in a room temperature water task followed by the cold pressor task and sociodemographic questionnaires. Throughout the study, electrocardiography and impedance cardiography were measured continuously, and five saliva samples were collected that were later assayed for cortisol and uric acid. Descriptively, uric acid increased about 32 min following completion of the cold pressor. Resting uric acid concentrations were not associated with the autonomic nervous system response, but higher resting uric acid concentrations were associated with increased cortisol concentrations. Future research should examine the extent to which the purinergic system influences, and is influenced by, other types of stress and other physiological systems. The current findings highlight the potential role of an understudied biomarker and physiological system in the stress literature and have implications for basic and mechanistic researchers who study psychoneuroendocrinology, stress, and health.

A new Febuxostat-Telmisartan Drug-Drug Cocrystal for Gout-Hypertension Combination Therapy

Drug-drug cocrystalllization is a novel mechanism for effective pharmacological combination therapy. In this work, we have demonstrated the preparation of a drug-drug cocrystal of a hypertension drug (Telmisartan; TEL) with a hyperuricemia drug (Febuxostat; FEB) in 1:1 molar ratio using a solvent evaporation method for the first time. Generally, a multi-component system may yield either a eutectic, salt, and/or a cocrystal. This study adopted a methodical orthogonal framework to analyze the final solid form. A single crystal X-ray structural investigation revealed the formation of a heterosynthon with carboxylic and benzimidazole groups of FEB and TEL, respectively, in the triclinic P-1 space group. ΔpKa of the heterosynthon is ∼1.5, hence, based on the empirical rules, a salt-cocrystal continuum is hypothesized. Further, attenuated total reflectance Fourier transform infrared (ATR-FTIR), and Raman spectroscopy were employed to corroborate the hydrogen bond formation in the heterosynthon (-N---H-O-), which confirmed the propensity for cocrystal formation. An accelerated stability study and an in vitro biorelevant dissolution study of the cocrystal were performed, which demonstrated that it is physiochemically stable, but it resulted in a slower dissolution rate when compared with plain drugs.

Association of uric acid levels with cardiac syndrome X: A meta-analysis

Objective: The pathogenesis of elevated uric acid (UA) levels in patients with cardiac syndrome X (CSX) is unclear, and the results presented in recent papers on UA levels in patients with CSX are controversial. Therefore, we conducted a meta- analysis to assess the relationship between UA levels and CSX.

Methods: Three databases, including the Web of Science, EMBASE and PubMed, were systematically searched until January 2022. Fixed-effect and random-effects models were used to analyze the relationship between UA levels and CSX. Subgroup analysis and sensitivity analysis were also performed.

Results: Six studies involving 406 CSX patients and 267 non-CSX were included. Our results showed a significant relationship between UA levels and CSX, with a pooled SMD of 0.68 (95% CI 0.37 to 1.00; p < 0.0001). We also found a close relationship between UA levels and CSX for patients ≥ 55 years old (SMD:0.70, 95% CI: 0.41 to 0.99, p < 0.00001), for patients < 55 years old (SMD: 0.68, 95% CI: 0.25 to 1.12, p =0 .002), for women ≥ 60% (SMD: 0.77, 95% CI: 0.33 to 1.14, p =0 .0004), for women < 60% (SMD: 0.61, 95% CI:0.23 to 0.98, p =0 .001), for BMI ≥ 28 Kg/m² (SMD :0.61, 95% CI: 0.23 to 0.98, p =0 .001), for BMI < 28 Kg/m² (SMD:0.75, 95% CI: 0.31 to 1.19, p =0 .0009), for publication years ≥ 2012 (SMD :0.69, 95% CI: 0.23 to 1.15, p = 0.003), for publication years < 2012 (SMD:0.73, 95% CI:0.41 to 1.05, p < 0.00001), and for Turkey (SMD:0.75, 95% CI:0.38 to 1.11, p <.0001). Sensitivity analysis showed that the pooled results remained consistent after removing any one study or converting the random-effects model to fixed-effects model.

Conclusion: Our results indicated a strong association between high UA levels and CSX. However, more well-designed studies are needed to investigate whether early treatment of hyperuricemia can reduce the incidence of CSX.

Cardiovascular risk associated with allopurinol or benzbromarone treatment in patients with gout

Background:

In previous studies, cardiovascular (CV) risk was increased in patients with gout. The effects of uric acid–lowering therapy on CV risk in gout patients have been investigated in numerous studies; however, allopurinol and benzbromarone have rarely been compared.

Objectives:

To compare CV risk based on allopurinol and benzbromarone treatment in Korean gout patients.

Design:

A nationwide population-based retrospective cohort study.

Methods:

We used South Korea database of the Health Insurance Review and Assessment (HIRA) service to identify gout patients ⩾18 years of age who newly started allopurinol or benzbromarone between 2009 and 2015. The primary outcome of the study was the occurrence of a composite CV endpoint, which included coronary revascularization, hospitalization due to myocardial infarction, ischemic stroke, and transient ischemic attack. Cox proportional hazard regression analysis and Kaplan–Meier curves were used for analysis.

Results:

The study included 257,097 allopurinol initiators and 7868 benzbromarone initiators. Compared with allopurinol initiators, the adjusted hazard ratio (aHR) of the composite CV endpoint of benzbromarone initiators was 1.01 [95% confidence interval (CI): 0.83−1.21], which was not significantly different. The results did not change even when 1:3 propensity score matching was performed for baseline characteristics. In subgroup analysis of high-risk patients with CV disease, significant difference was not observed between allopurinol and benzbromarone initiators.

Conclusion:

In this study, significant difference was not found in CV risk between allopurinol and benzbromarone initiators. In the high-CV-risk group, the incidence of CV events did not differ between allopurinol and benzbromarone initiators.

Correlation of obesity, dietary patterns, and blood pressure with uric acid: data from the NHANES 2017-2018

BACKGROUND

Prevalence rates of hyperuricemia and gout are increasing. Clinical investigations of hyperuricemia-related risk factors aid in the early detection, prevention, and management of hyperuricemia and gout. Ongoing research is examining the association of obesity, dietary patterns, and blood pressure (BP) with serum uric acid (sUA).

METHODS

A cross-sectional study was conducted based on the National Health and Nutrition Examination Survey. The exposures included body mass index (BMI), dietary patterns, and BP. The outcome variable was sUA level. The weighted multivariate linear regression models and smooth curve fittings were used to assess the association of BMI, dietary patterns, and BP with sUA.

RESULTS

There was a significantly positive correlation between BMI and sUA (β = 0.059, 95% CI: 0.054 to 0.064, P < 0.00001). Overweight and obese individuals had higher sUA levels than those with the normal BMI (β = 0.451, 95% CI: 0.357 to 0.546, P < 0.00001; β = 0.853, 95% CI: 0.760 to 0.946, P < 0.00001; respectively). Dietary energy intake was positively correlated with sUA (β = 0.000, 95% CI: 0.000 to 0.000, P = 0.01057). Dietary intake of carbohydrate and fiber were negatively correlated with sUA (β = - 0.001, 95% CI: - 0.002 to - 0.000, P < 0.00001; β = - 0.008, 95% CI: - 0.011 to - 0.004, P = 0.00001; respectively). Moreover, systolic BP was positively correlated with sUA (β = 0.006, 95% CI: 0.003 to 0.009, P = 0.00002). However, no statistical differences were found about the associations of dietary intake of total sugars, protein, total fat, cholesterol, and diastolic BP with sUA.

CONCLUSIONS

The current cross-sectional investigation of a nationally representative sample of US participants showed that BMI, dietary energy intake, and systolic BP were positively correlated with sUA levels; dietary carbohydrate and fiber intake were negatively correlated with sUA levels. The findings might be helpful for the management and treatment of hyperuricemia and gout.

Update on Hypertension Research in 2021

In 2021, 217 excellent manuscripts were published in Hypertension Research. Editorial teams greatly appreciate the authors' contribution to hypertension research progress. Here, our editorial members have summarized twelve topics from published work and discussed current topics in depth. We hope you enjoy our special feature, "Update on Hypertension Research in 2021".

The reality of treatment for hyperuricemia and gout in Japan: A historical cohort study using health insurance claims data

Hyperuricemia causes gout and has also been associated with metabolic syndrome and cardiovascular disease. Uric acid‐lowering drugs (ULDs) are used to reduce uric acid levels for the treatment of hyperuricemia and gout. However, there is a lack of robust and real‐world data on the history and treatment of patients with newly diagnosed hyperuricemia or gout in Japan. This retrospective, longitudinal, historical cohort study determined the characteristics of patients with hyperuricemia and/or gout, and prescription of, and adherence to, ULDs using data from the JMDC Claims Database. The primary evaluation population included 64 677 patients with newly diagnosed hyperuricemia and/or gout. Of these, only 26 501 (41.0%) had a prescription for ULDs at diagnosis. Even when ULDs were prescribed, the persistence rate of prescriptions declined over time, with a 54.4% persistence rate for ULDs at 12 months after the index diagnosis. In subgroups of patients with or without hypertension and diabetes, the rate of ULD prescription continuation was significantly higher in those with comorbidities than in those without (76.8% vs. 42.6% in those with vs. without hypertension, and 78.7% vs. 52.2% in those with vs. without diabetes). These finding suggest that therapeutic interventions to lower serum uric acid levels are under‐utilized for patients with newly diagnosed hyperuricemia and/or gout in Japan.

Serum Uric Acid Levels and Cardiometabolic Profile in Middle-Aged, Treatment-Naïve Hypertensive Patients

INTRODUCTION

Uric acid (UA) is a risk factor associated with cardiometabolic diseases. However, the appropriate threshold of UA remains a matter of controversy.

AIM

To assess whether slightly increased UA levels have any significance in middle-aged, treatment-naïve persons with new-onset hypertension.

METHODS

In this cross-sectional study we recruited middle-aged participants with new-onset hypertension who were treatment-naïve. Subjects below (Group 1) and above the median UA levels (Group 2) were compared regarding clinical and laboratory characteristics that are implicated in cardiovascular and renal risk. The study population consisted of 369 persons (mean age 48.4±10 years) with median UA of 4.8 mg/dl. Group 2 individuals were predominantly male and had higher levels of blood pressure, increased body mass index, waist circumference, and a greater degree of insulin resistance. Additionally, greater lipid profile abnormalities were detected. This group also exhibited a significantly decreased fractional excretion of UA. Multivariate analysis demonstrated that serum UA levels were correlated with male sex, waist circumference, estimated glomerular filtration rate (eGFR), serum calcium and insulin levels, as well as with fractional excretion of UA. A positive association between serum UA levels and the number diagnostic criteria of the metabolic syndrome (MtS) was also noticed. After reclassification of subjects according to UA quartiles, individuals with UA levels ≥ 3.8 mg/dl had significantly higher odds (2.5-fold to 9.8-fold) of having MtS after adjustment of age, sex, and eGFR.

CONCLUSIONS

Uric acid levels in middle-aged, treatment-naïve hypertensive patients are correlated with risk factors for cardiovascular and renal disease.

Association between serum uric acid with diabetes and other biochemical markers

Objective

This study aimed to decipher the association between serum uric acid (UA) and glycated hemoglobin (HbA1c) in the population from the southern region of Saudi Arabia.

Method

In this retrospective cross-sectional investigation, clinical data obtained from the different commercial laboratories in the Asir region of Saudi Arabia were screened over 2 years. Data were analyzed using standard statistical methods.

Results

A total of 1984 laboratory investigations with 1215 females (61.2%) and 769 males (38.6%) were included in the data analysis. In our investigation, the prevalence of hyperuricemia in the study population was 53.5% (41.2% females and 12.3% males) and in the diabetic population was 12.7% (9.47% females and 3.23% males), in prediabetics was 12.65% (9.8% females and 2.85% males), respectively. Prediabetic subjects had higher UA levels than people with diabetes or healthy people. Higher UA quartiles were associated with a high level of urea, blood urea nitrogen (BUN) creatinine, HbA1c, fasting blood sugar (FBS), and total cholesterol (TC) (P < 0.05). High UA (OR = 1.33 for diabetes; OR = 2.676 for prediabetes), high BUN (OR = 3.05 for diabetes; OR = 2.293 for prediabetes), high TC (OR = 3.75 for diabetes; OR = 1.098 for prediabetes), and high TG (OR = 2.67 for diabetes; OR = 1.943 for prediabetes) parameters are the most influential risk factor in diabetic and prediabetic patients than the people who have normal UA, BUN, TC, and TG value.

Conclusion

High UA levels are significantly associated with prediabetes as defined by HbA1c criteria, indicating that UA has a significant role in the disturbance of glucose metabolism. A significant positive association was observed between dyslipidemia and serum UA in the study population.

Impact of hyperuricemia on chronic kidney disease and atherosclerotic cardiovascular disease

Hyperuricemia is caused by reduced renal/extrarenal excretion and overproduction of uric acid. It is affected by genetic predisposition related to uric acid transporters and by visceral fat accumulation due to overnutrition. The typical symptomatic complication of hyperuricemia is gout caused by monosodium urate crystals. Accumulated evidence from epidemiological studies suggests that hyperuricemia is also a risk factor for hypertension, chronic kidney disease (CKD) and atherosclerotic cardiovascular disease (CVD). However, it remains to be determined whether urate-lowering therapy for asymptomatic patients with hyperuricemia is effective in preventing CKD or CVD progression. This mini review focuses mainly on recent papers investigating the relationship between hyperuricemia and CKD or CVD and studies of urate-lowering therapy. Accumulated studies have proposed mechanisms of renal damage and atherosclerosis in hyperuricemia, including inflammasome activation, decreased nitric oxide bioavailability and oxidative stress induced by uric acid, urate crystals and xanthine oxidoreductase (XOR)-mediated reactive oxygen species. Since patients with hyperuricemia are a heterogeneous population with complex pathologies, it may be important to assess whether an outcome is the result of decreasing serum uric acid levels or an inhibitory effect on XOR. To clarify the impact of hyperuricemia on CKD and CVD progression, high-quality and detailed clinical and basic science studies of hyperuricemia and purine metabolism are needed.

Prospective Study of Serum Uric Acid Levels and First Stroke Events in Chinese Adults With Hypertension

Objectives: We investigated the association between serum uric acid (SUA) levels and the risk of the first stroke in Chinese adults with hypertension.

Methods: A total of 11, 841 hypertensive patients were selected from the Chinese Hypertension Registry for analysis. The relationship between SUA levels and first stroke was determined using multivariable Cox proportional hazards regression, smoothing curve fitting, and Kaplan–Meier survival curve analysis.

Results: During a median follow-up of 614 days, 99 cases of the first stroke were occurred. Cox proportional hazards models indicated that SUA levels were not significantly associated with the first stroke event [adjusted-hazard ratio (HR) per SD increase: 0.98, 95% CI 0.76–1.26, P = 0.889]. In comparison to the group without hyperuricemia (HUA), there were no significantly higher risks of first stroke events (adjusted-HR: 1.22, 95% CI 0.79–1.90, P = 0.373) in the population with HUA. However, in the population less than 60 years old, subjects with HUA had a significantly higher risk of the first stroke than the population without HUA (adjusted-HR: 4.89, 95% CI 1.36–17.63, P = 0.015). In subjects older than 60 years, we did not find a significant relationship between HUA and first stroke (adjusted-HR: 0.97, 95% CI 0.60–1.56, P = 0.886). Survival analysis further confirmed this discrepancy (log-rank P = 0.013 or 0.899 for non-aging or aging group).

Conclusion: No significant evidence in the present study indicated that increased SUA levels were associated with the risk of first stroke in the Chinese adults with hypertension. Age played an interactive role in the relationship between HUA and the first stroke event.

Prevalence, patterns and predictors of metabolic abnormalities in Nigerian hypertensives with hypertriglyceridemic waist phenotype: A cross sectional study

BACKGROUND

Simultaneous presence of elevated waist circumference and hypertriglyceridemia (HTGW) is a simple and low-cost measure of visceral obesity, and it is associated with a plethora of cardio-metabolic abnormalities that can increase the risk of cardiovascular diseases and incident Type 2 diabetes mellitus. We decided to study the prevalence, patterns, and predictors of metabolic abnormalities in Nigerian hypertensives with the HTGW phenotype.

METHODS

The medical records of 582 hypertensives with complete data of interest were retrieved and analyzed for the study. Their socio-demographic data, anthropometric data, and booking blood pressure values were retrieved. The results of their fasting plasma glucose, lipid profile, uric acid and serum creatinine were also retrieved for analysis.

RESULTS

The mean age of the study population was 56.2 ±13.6, with 53.1% being males. The prevalence of smoking and use of alcohol was 4.3% and 26.5% respectively. The prevalence of the HTGW phenotype was 23.4% and were predominantly males (61%). Subjects with the HTGW phenotype were more obese assessed by waist circumference (WC) and body mass index (BMI). Mean serum total cholesterol, triglyceride, very low-density lipoprotein, uric acid, and creatinine were significantly higher in the HTGW phenotype (p = 0.003; <0.001; <0.001; 0.002 and <0.001 respectively). The prevalence of newly diagnosed Type 2 diabetes was 28.7%. There was also a preponderance of cardio-metabolic abnormalities (obesity, dyslipidaemia, hyperuricemia) in the HTGW phenotype. In both males and females, the HGTW phenotype was significantly associated with elevated Tc, TG, VLDL, hyperuricemia and atherogenic index of plasma.

CONCLUSION

The HTGW phenotype is common amongst Nigerian hypertensives, and it is associated with metabolic abnormalities.

Evaluation of Risk Factors Associated With Antihypertensive Treatment Success Employing Data Mining Techniques

Objective:

This study aimed to evaluate the effects of potential risk factors on antihypertensive treatment success.

Methods:

Patients with hypertension who were treated with antihypertensive medications were included in this study. Data from the last visit were analyzed retrospectively for each patient. To evaluate the predictive models for antihypertensive treatment success, data mining algorithms (logistic regression, decision tree, random forest, and artificial neural network) using 5-fold cross-validation were applied. Additionally, study parameters between patients with controlled and uncontrolled hypertension were statistically compared and multiple regression analyses were conducted for secondary endpoints.

Results:

The data of 592 patients were included in the analysis. The overall blood pressure control rate was 44%. The performance of random forest algorithm (accuracy = 97.46%, precision = 97.08%, F1 score = 97.04%) was slightly higher than other data mining algorithms including logistic regression (accuracy = 87.31%, precision = 86.21%, F1 score = 85.74%), decision tree (accuracy = 76.94%, precision = 70.64%, F1 score = 76.54%), and artificial neural network (accuracy = 86.47%, precision = 83.85%, F1 score = 84.86%). The top 5 important categorical variables (predictive correlation value) contributed the most to the prediction of antihypertensive treatment success were use of calcium channel blocker (−0.18), number of antihypertensive medications (0.18), female gender (0.10), alcohol use (−0.09) and attendance at regular follow up visits (0.09), respectively. The top 5 numerical variables contributed the most to the prediction of antihypertensive treatment success were blood urea nitrogen (−0.12), glucose (−0.12), hemoglobin A1c (−0.12), uric acid (−0.09) and creatinine (−0.07), respectively. According to the decision tree model; age, gender, regular attendance at follow-up visits, and diabetes status were identified as the most critical patterns for stratifying the patients.

Conclusion:

Data mining algorithms have the potential to produce predictive models for screening the antihypertensive treatment success. Further research on larger populations and longitudinal datasets are required to improve the models.

Annual reports on hypertension research 2020

In 2020, 199 papers were published in Hypertension Research. Many excellent papers have contributed to progress in research on hypertension. Here, our editorial members have summarized eleven topics from published work and discussed current topics in depth. We hope you enjoy our special feature, Annual Reports on Hypertension Research.

Therapeutic enzymes as non-conventional targets in cardiovascular impairments:A Comprehensive Review

Over the last few decades, substantial progress has been made towards the understanding of cardiovascular diseases (CVDs). In-depth mechanistic insights have also provided opportunities to explore novel therapeutic targets and treatment regimens to be discovered. Therapeutic enzymes are an example of such opportunities. The balanced functioning of such enzymes protects against a variety of CVDs while on the other hand, even a small shift in the normal functioning of these enzymes may lead to deleterious outcomes. Owing to the great versatility of these enzymes, inhibition and activation are key regulatory approaches to counter the onset and progression of several cardiovascular impairments. While cardiovascular remedies are already available in excess and of course they are efficacious, a comprehensive description of novel therapeutic enzymes to combat CVDs is the need of the hour. In light of this, the regulation of the functional activity of these enzymes also opens a new avenue for the treatment approaches to be employed. This review describes the importance of non-conventional enzymes as potential candidates in several cardiovascular disorders while highlighting some of the recently targeted therapeutic enzymes in CVDs.

High uric acid levels in overweight and obese children and their relationship with cardiometabolic risk factors: what is missing in this puzzle?

OBJECTIVES

The prevalence of hyperuricemia, a common disorder, has been increasing. Moreover, the association between obesity, serum uric acid levels, and cardiometabolic markers in children is unclear. Therefore, this study aimed to analyze the inter-relationships between these factors in a sample of children aged 6-12 years.

METHODS

We evaluated 764 children and stratified them according to their body mass index (BMI). Blood pressure and uric acid, creatinine, lipid, and glycemic profiles were evaluated, and the estimated glomerular filtration rate (eGFR) and the homeostatic model assessment for insulin resistance (HOMA-IR) index were calculated.

RESULTS

There was a significant linear trend of increasing systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), total cholesterol, low-density lipoprotein cholesterol (LDLc), uric acid, insulin levels, and HOMA-IR index values corresponding with overweight and obese groups; however, high-density lipoprotein cholesterol (HDLc) levels decreased with increasing obesity. The mean creatinine level and eGFR were similar across all BMI groups. Uric acid levels were significantly correlated with BMI (r=0.527), waist circumference (r=0.580), SBP (r=0.497), DBP (r=0.362), TG (r=0.534), total cholesterol (r=0.416), LDLc (r=0.286), HDLc (r=-0.248), insulin (r=0.613), and HOMA-IR index (r=0.607). Multiple regression analyses showed that BMI (B=0.071; SE=0.012; p<0.001), TG (B=0.004; SE=0.001; p<0.001), LDLc (B=0.003; SE=0.001; p=0.006), and insulin (B=0.066; SE=0.007; p<0.001) (R²=0.460) were significant predictors of increased uric acid levels and explained 46% of the variability in uric acid in these children.

CONCLUSIONS

Our findings suggest that overweight or obese children are more likely to have higher uric acid levels. Moreover, several cardiometabolic risk factors were strongly associated with high uric acid levels.

Association of uric acid and uric acid to creatinine ratio with chronic kidney disease in hypertensive patients

Background

Recent studies have shown that the serum uric acid/creatinine ratio (SUA/SCr) is a better predictor of chronic kidney disease (CKD) than serum uric acid (SUA) isolated. The aim of the present study was to evaluate the association of isolated SUA and the SUA/SCr with CKD in hypertensive patients.

Methods

Cross-sectional study conducted with hypertensive patients followed-up by the Primary Health Care Service (PHC). Sociodemographic, economic, lifestyle, clinical, anthropometric, and biochemical variables were evaluated. The association between SUA parameters (quartiles of SUA and quartiles of SUA/SCr) and CKD was evaluated by bivariate and multivariate logistic regression. The association between SUA parameters (SUA and SUA/SCr) and estimated glomerular filtration rate (eGFR) was evaluated by linear regression. The analyses were performed considering four adjustment models. SUA and SUA/SCr were compared by receiver operating characteristic (ROC) curve.

Results

In the fully adjusted model, SUA was positively associated with the presence of CKD (OR = 6.72 [95 % CI 1.96–22.96]) and inversely associated with eGFR (β Coef. = -2.41 [95 % CI -3.44; -1.39]). SUA/SCr was positively associated with eGFR (β Coef. = 2.39 [1.42; 3.36]). According to the ROC curve, the SUA is a better predictor of CKD than the SUA/SCr.

Conclusions

Elevated levels of isolated SUA were associated with CKD and eGFR. However, the SUA/SCr was not associated with CKD. We do not recommend using the SUA/SCr to predict CKD in hypertensive patients.

Evaluation of uric acid disorders and associated factors in essential hypertensive patients at Wolkite University specialized hospital, Southern Ethiopia

BACKGROUND

Essential hypertension is a condition characterized by a rise in blood pressure of undetermined cause, includes 90% of all hypertensive cases and is a highly important public health challenge with major modifiable cause of morbidity and mortality. Uric acids disorders in particular hyperuricemia are significant problems in essential hypertensive patients and can cause substantial morbidity and mortality. Determination of uric acid disorders may play a major role in the management and early aversion of complications in hypertensive patient. Therefore, this study aimed to determine uric acid disorders and associated factors among essential hypertensive adults in the outpatient department at Wolkite University specialized Hospital, Southern Ethiopia from November 1 to February 30, 2021.

METHODS AND MATERIALS

An institional based cross sectional study was conducted on 270 essential hypertensive adults on follow-up in outpatient department from November 1 to February 30, 2021. Structured questionnaires through face to face interviews and participants' medical records were used to collect information on determinants related with uric acid disorders. The blood specimen was collected and level of serum uric acid, blood sugar and lipid profile was measured using standard principles and procedures with an ABX Pentra 400 automated chemistry analyzer. Bivariate and multivariate logistic regression analyses were done to identify factors associated with hyperuricemia. The p-value was set at <0.05 with a 95% confidence interval of the adjusted odds ratio.

RESULTS

A total of 270 adult essential hypertensive patients were participated in the study, among those 196(27.4%) of study participants were hyperuricemic with 95%CI (21.9, 33.3). Being alcoholic [(AOR: 15.68, 95% CI: (5.93, 21.41)], taking antihypertensive medication [(AOR: 11.56, 95% CI: (3.94, 23.80)], BMI > = 30 [(AOR: 4.89, 95% CI: (1.46, 25.5)] and being centrally obese [(AOR: 6.87, 95% CI: (2.53, 18.63)] were factors significantly associated with hyperuricemia.

CONCLUSION

In this study, the high burden of hyperuricemia (27.4%) was observed in essential hypertensive patients with follow-up in outpatient department. Taking alcohol and antihypertensive medication, being overweight and centrally obese were identified factors of uric acid disorders. The finding of this study should be taken into consideration to implement preventive interventions on identified predictors in hypertensive patients. Taking fruit and vegetable, and promoting physical exercise and determinations of serum uric acid level in adult essential hypertensive patients was recommended to minimize the emergence of hyperuricemia.

Purine metabolites and complex diseases: role of genes and nutrients

PURPOSE OF REVIEW

Purines have several important physiological functions as part of nucleic acids and as intracellular and extracellular signaling molecules. Purine metabolites, particularly uric acid, have been implicated in congenital and complex diseases. However, their role in complex diseases is not clear and they have both beneficial and detrimental effects on disease pathogenesis. In addition, the relationship between purines and complex diseases is affected by genetic and nutritional factors. This review presents latest findings about the relationship between purines and complex diseases and the effect of genes and nutrients on this relationship.

RECENT FINDINGS

Evidence from recent studies show strong role of purines in complex diseases. Although they are causal in only few diseases, our knowledge about their role in other diseases is still evolving. Of all the purines, uric acid is the most studied. Uric acid acts as an antioxidant as well as a prooxidant under different conditions, thus, its role in disease also varies. Other purines, adenosine and inosine have been less studied, but they have neuroprotective properties which are valuable in neurodegenerative diseases.

SUMMARY

Purines are molecules with great potential in disease pathogenesis as either metabolic markers or therapeutic targets. More studies need to be conducted to understand their relevance for complex diseases.

The Role of ABCG2 in the Pathogenesis of Primary Hyperuricemia and Gout-An Update

Urate homeostasis in humans is a complex and highly heritable process that involves i.e., metabolic urate biosynthesis, renal urate reabsorption, as well as renal and extrarenal urate excretion. Importantly, disturbances in urate excretion are a common cause of hyperuricemia and gout. The majority of urate is eliminated by glomerular filtration in the kidney followed by an, as yet, not fully elucidated interplay of multiple transporters involved in the reabsorption or excretion of urate in the succeeding segments of the nephron. In this context, genome-wide association studies and subsequent functional analyses have identified the ATP-binding cassette (ABC) transporter ABCG2 as an important urate transporter and have highlighted the role of single nucleotide polymorphisms (SNPs) in the pathogenesis of reduced cellular urate efflux, hyperuricemia, and early-onset gout. Recent publications also suggest that ABCG2 is particularly involved in intestinal urate elimination and thus may represent an interesting new target for pharmacotherapeutic intervention in hyperuricemia and gout. In this review, we specifically address the involvement of ABCG2 in renal and extrarenal urate elimination. In addition, we will shed light on newly identified polymorphisms in ABCG2 associated with early-onset gout.

Modulation of Urate Transport by Drugs

BACKGROUND

Serum urate (SU) levels in primates are extraordinarily high among mammals. Urate is a Janus-faced molecule that acts physiologically as a protective antioxidant but provokes inflammation and gout when it precipitates at high concentrations. Transporters play crucial roles in urate disposition, and drugs that interact with urate transporters either by intention or by accident may modulate SU levels. We examined whether in vitro transporter interaction studies may clarify and predict such effects.

METHODS

Transporter interaction profiles of clinically proven urate-lowering (uricosuric) and hyperuricemic drugs were compiled from the literature, and the predictive value of in vitro-derived cut-offs like C_max/IC₅₀ on the in vivo outcome (clinically relevant decrease or increase of SU) was assessed.

RESULTS

Interaction with the major reabsorptive urate transporter URAT1 appears to be dominant over interactions with secretory transporters in determining the net effect of a drug on SU levels. In vitro inhibition interpreted using the recommended cut-offs is useful at predicting the clinical outcome.

CONCLUSIONS

In vitro safety assessments regarding urate transport should be done early in drug development to identify candidates at risk of causing major imbalances. Attention should be paid both to the inhibition of secretory transporters and inhibition or trans-stimulation of reabsorptive transporters, especially URAT1.

How to Differentiate Gout, Calcium Pyrophosphate Deposition Disease, and Osteoarthritis Using Just Four Clinical Parameters

Clinical differentiation between gout, osteoarthritis (OA), and calcium pyrophosphate deposition disease (CPPD) remains a hurdle in daily practice without imaging or arthrocentesis. We performed a retrospective analysis of consecutive patients with gout, CPPD, and OA at a tertiary rheumatology center. A total of 277 patients were enrolled, with 164 suffering from gout, 76 from CPPD, and 37 from OA. We used ANOVA and conditional inference tree analysis (Ctrees) to find associations between clinical, laboratory, and imaging data and gout, OA, and CPPD. The sonographic double contour sign was unable to differentiate gout from CPPD. Ctrees were able to exclude OA and CPPD as possible differentials based on elevated uric acid, C-reactive protein (CRP), presence of arterial hypertension, and sex, diagnosing gout with a sensitivity and specificity of 95.1% and 41.6%, respectively. Elevated CRP was observed using simple linear regressions in patients with type II diabetes, higher cumulative joint scores, increased number of affected joints, as well as elevated uric acid, erythrocyte sedimentation rate, and leukocyte count. Ctrees were able to differentiate gout, OA, and CPPD based on just four characteristics. Inflammatory response correlated with type II diabetes, more or larger joint involvement, and elevated uric acid levels.

The inflammatory state is a risk factor for cardiovascular disease and graft fibrosis in kidney transplantation

Several factors, such as donor brain death, ischemia-reperfusion injury, rejection, infection, and chronic allograft dysfunction, may induce an inflammatory state in kidney transplantation. Furthermore, inflammatory cells, cytokines, growth factors, complement and coagulation cascade create an unbalanced interaction with innate and adaptive immunity, which are both heavily involved in atherogenesis. The crosstalk between inflammation and thrombosis may lead to a prothrombotic state and impaired fibrinolysis in kidney transplant recipients increasing the risk of cardiovascular disease. Inflammation is also associated with elevated levels of fibroblast growth factor 23 and low levels of Klotho, which contribute to major adverse cardiovascular events. Hyperuricemia, glucose intolerance, arterial hypertension, dyslipidemia, and physical inactivity may create a condition called metaflammation that concurs in atherogenesis. Another major consequence of the inflammatory state is the development of chronic hypoxia that through the mediation of interleukins 1 and 6, angiotensin II, and transforming growth factor beta can result in excessive accumulation of extracellular matrix, which can disrupt and replace functional parenchyma, leading to interstitial fibrosis and chronic allograft dysfunction. Lifestyle and regular physical activity may reduce inflammation. Several drugs have been proposed to control the graft inflammatory state, including low-dose aspirin, statins, renin-angiotensin inhibitors, xanthine-oxidase inhibitors, vitamin D supplements, and interleukin-6 blockade. However, no prospective controlled trial with these measures has been conducted in kidney transplantation.

Ameliorative potentials of Persea americana leaf extract on toxicants - induced oxidative assault in multiple organs of wistar albino rat

Background

Persea americana (PA) is a popular medicinal plant in folkloric medicines. The present study therefore investigates the ameliorative potentials of its leaves extract on carbon tetrachloride and rifampicin-induced toxicity in the liver, kidney and heart of albino rat. This was aimed at assessing the potentials of the plant in the management of liver, kidney and heart diseases.

Methodology

Forty (40) rats were randomly divided into eight (8) groups of five animals each. Groups I and II were administered with only distilled water and carbon tetrachloride (CCl4) respectively. Groups III and IV animals received 3.0 ml/kg bw of CCl4 and were treated with the extract at 50 mg/kg bw and 100 mg/kg respectively, while group V received 100 mg/kg bw. of silymarin orally for 14 days. Groups VI animals were administered with rifampicin (250 mg/kg bw.) only, while groups VII and VIII animals received rifampicin and were treated with 50 mg and 100 mg/kg bw of the extract respectively. Activities of creatine kinase, aspartate amino transferase, alanine amino transferase, alkaline phosphatase, superoxide dismutase, catalase as well as levels of urea, uric acid, bilirubin and malonidialdehyde (MDA) were assayed. Lipid profiles and histopathological examination of liver and kidney slices were also performed.

Result

Treatment with P. americana significantly (p < 0.05) restored all deranged biochemical parameters (creatine kinase, aspartate amino transferase, alanine amino transferase, alkaline phosphatase, urea, uric acid, bilirubin, MDA, lipid profile as well as superoxide dismutase and catalase) in a dose-dependent manner. Normal hepatic and renal histoarchitecture were also restored following treatment with P. americana.

Conclusion

Amelioration of distorted cardiac, hepatic and renal histoarchitecture as well as restoration of lipid profile, biomarkers of liver and kidney injury and antioxidant enzymes (catalase and superoxide dismutase) affirm the potential usefulness of P. americana in the management of liver, kidney and heart diseases.

Comparative effects of topiroxostat and febuxostat on arterial properties in hypertensive patients with hyperuricemia

Elevated serum uric acid is a cardiovascular risk factor in patients with hypertension, even when blood pressure (BP) is well controlled. Xanthine oxidoreductase inhibitors (XORi) reduce serum uric acid levels and have several other potential effects. This multicenter, randomized, open‐label study compared the effects of two XORi, topiroxostat and febuxostat, on arterial stiffness, uric acid levels, and BP in hypertensive patients with hyperuricemia. Patients received topiroxostat 40–160 mg/day or febuxostat 10–60 mg/day, titrated to maintain serum uric acid <6 mg/dl, for 24 weeks. The primary endpoint was change in the cardio‐ankle vascular index (CAVI) from baseline to 24 weeks. There were no significant changes in CAVI from baseline to 24 weeks (from 9.13 to 9.16 [feboxustat] and 8.98 to 9.01 [topiroxostat]). Compared with baseline, there were significant reductions in serum uric acid (–2.9 and –2.5 mg/dl; both p < 0.001) and morning home systolic BP (–3.6 and –5.1 mm Hg; both p < 0.01) after 24 weeks' treatment with febuxostat and topiroxostat. BP decreased to the greatest extent in the subgroup of patients with uncontrolled blood pressure at baseline. Topiroxostat, but not febuxostat, significantly decreased plasma xanthine oxidoreductase activity versus baseline. The urinary albumin‐creatinine ratio (UACR) decreased significantly from baseline to 24 weeks with topiroxostat (–20.8%; p = 0.021), but not febuxostat (–8.8%; p = 0.362). In conclusion, neither topiroxostat nor febuxostat had any significant effects on arterial stiffness over 24 weeks' treatment.

Uric Acid Potential Role in Systemic Inflammation and Negative Symptoms After Acute Antipsychotic Treatment in Schizophrenia

Uric acid (UA) has been shown to have neuroprotective or neurotoxic properties, in relation to specific tissues and diseases that have been studied. Previous studies provided contradictory results on the role of UA in schizophrenia as a neurodegenerative disorder. The aim of this brief report was an additional analysis of UA sera levels in different phases of schizophrenia. Here, 86 patients with first-episode psychosis (FEP) vs. 45 patients with schizophrenia in relapse (SC in relapse) vs. 35 healthy control subjects (HC) were studied before and 1 month after antipsychotic therapy. Further, we aimed to explore the possible correlation of UA with scores presenting clinical features and with serum concentrations of the proinflammatory cytokines interleukin (IL)-6 and IL-17. When comparing the data between all three groups, we did not find significant differences in UA levels, either before or after the applied therapy. Also, comparing sera concentrations of UA in every single group, the analysis did not reveal statistically significant differences between FEP patients, but statistically, a significant difference was found in SC in relapse before and after treatment (334.71 ± 116.84 vs. 289.37 ± 109.15 μmol/L, p = 0.05). Uric acid serum levels correlated with negative sub-score (p = 0.001, r = 0.306), general sub-score (p = 0.015, r = 0.236), and total PANSS score (p = 0.009, r = 0.3) after 1 month of therapy. We have established a statistically significant positive correlation between serum concentrations of UA and IL-6 in exacerbation (p = 0.01, r = 0.220) and with IL-17 after treatment and in the stabilization of psychosis (p = 0.01, r = 0.34), suggesting potential cascades in different phases of schizophrenia that potentiate inflammation.