A pilot study on the impact of a low fructose diet and allopurinol on clinic blood pressure among overweight and prehypertensive subjects: a randomized placebo controlled trial

Efficacy of angiotensin receptor blockers for nocturnal blood pressure reduction: a systematic review and meta-analysis

BACKGROUND

Nocturnal blood pressure (BP) is correlated with an increased risk of cardiovascular events and is an important predictor of cardiovascular death in hypertensive patients.

OBJECTIVE

Nocturnal BP control is of great importance for cardiovascular risk reduction. This systematic review and meta-analysis aimed to explore the efficacy of angiotensin receptor blockers (ARBs) for nocturnal BP reduction in patients with mild to moderate hypertension.

METHODS

PICOS design structure was used to formulate the data extraction. All statistical calculations and analyses were performed with R.

RESULTS

Seventy-seven studies with 13,314 participants were included. The overall analysis indicated that nocturnal BP drop varied considerably among different ARBs. Allisartan (13.04 [95% CI (-18.41, -7.68)] mmHg), olmesartan (11.67 [95% CI (-14.12, -9.21)] mmHg), telmisartan (11.11 [95% CI (-12.12, -10.11)] mmHg) were associated with greater reduction in nocturnal systolic BP. In the aspect of the nocturnal-diurnal BP drop ratio, only allisartan was greater than 1. While, the variation tendency of last 4-6 h ambulatory BP was basically consistent with nocturnal BP. Additionally, allisartan showed improvement effect in the proportion of patients with dipping BP pattern.

CONCLUSIONS

This study demonstrates that for patients with mild to moderate hypertension, allisartan, olmesartan and telmisartan have more advantages in nocturnal BP reduction among the ARBs, while allisartan can reduce nighttime BP more than daytime BP and improve the dipping pattern.

Fructose-containing food sources and blood pressure: A systematic review and meta-analysis of controlled feeding trials

Whether food source or energy mediates the effect of fructose-containing sugars on blood pressure (BP) is unclear. We conducted a systematic review and meta-analysis of the effect of different food sources of fructose-containing sugars at different levels of energy control on BP. We searched MEDLINE, Embase and the Cochrane Library through June 2021 for controlled trials ≥7-days. We prespecified 4 trial designs: substitution (energy matched substitution of sugars); addition (excess energy from sugars added); subtraction (excess energy from sugars subtracted); and ad libitum (energy from sugars freely replaced). Outcomes were systolic and diastolic BP. Independent reviewers extracted data. GRADE assessed the certainty of evidence. We included 93 reports (147 trial comparisons, N = 5,213) assessing 12 different food sources across 4 energy control levels in adults with and without hypertension or at risk for hypertension. Total fructose-containing sugars had no effect in substitution, subtraction, or ad libitum trials but decreased systolic and diastolic BP in addition trials (P<0.05). There was evidence of interaction/influence by food source: fruit and 100% fruit juice decreased and mixed sources (with sugar-sweetened beverages [SSBs]) increased BP in addition trials and the removal of SSBs (linear dose response gradient) and mixed sources (with SSBs) decreased BP in subtraction trials. The certainty of evidence was generally moderate. Food source and energy control appear to mediate the effect of fructose-containing sugars on BP. The evidence provides a good indication that fruit and 100% fruit juice at low doses (up to or less than the public health threshold of ~10% E) lead to small, but important reductions in BP, while the addition of excess energy of mixed sources (with SSBs) at high doses (up to 23%) leads to moderate increases and their removal or the removal of SSBs alone (up to ~20% E) leads to small, but important decreases in BP in adults with and without hypertension or at risk for hypertension. Trial registration: Clinicaltrials.gov: NCT02716870.

Effect of weight loss on blood pressure changes in overweight patients: A systematic review and meta-analysis

To determine quantitative differences between weight loss and changes in clinic blood pressure (BP) and ambulatory BP in patients with obesity or overweight, the authors performed a meta-analysis. PubMed, Embase, and Scopus databases were searched up to June 2022. Studies that compared clinic or ambulatory BP with weight loss were included. A random effect model was applied to pool the differences between clinic BP and ambulatory BP. Thirty-five studies, for a total of 3219 patients were included in this meta-analysis. The clinic systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly reduced by 5.79 mmHg (95% CI, 3.54-8.05) and 3.36 mmHg (95% CI, 1.93-4.75) after a mean body mass index (BMI) reduction of 2.27 kg/m² , and the SBP and DBP were significantly reduced by 6.65 mmHg (95% CI, 5.16-8.14) and 3.63 mmHg (95% CI, 2.03-5.24) after a mean BMI reduction of 4.12 kg/m² . The BP reductions were much larger in patients with a BMI decrease ≥3 kg/m² than in patients with less BMI decrease, both for clinic SBP [8.54 mmHg (95% CI, 4.62-12.47)] versus [3.83 mmHg (95% CI, 1.22-6.45)] and clinic DBP [3.45 mmHg (95% CI, 1.59-5.30)] versus [3.15 mmHg (95% CI, 1.21-5.10)]. The significant reduction of the clinic and ambulatory BP followed the weight loss, and this phenomenon could be more notable after medical intervention and a larger weight loss.

Important food sources of fructose-containing sugars and adiposity: A systematic review and meta-analysis of controlled feeding trials

BACKGROUND

Sugar-sweetened beverages (SSBs) providing excess energy increase adiposity. The effect of other food sources of sugars at different energy control levels is unclear.

OBJECTIVES

To determine the effect of food sources of fructose-containing sugars by energy control on adiposity.

METHODS

In this systematic review and meta-analysis, MEDLINE, Embase, and Cochrane Library were searched through April 2022 for controlled trials ≥2 wk. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars), addition (energy from sugars added), subtraction (energy from sugars subtracted), and ad libitum (energy from sugars freely replaced). Independent authors extracted data. The primary outcome was body weight. Secondary outcomes included other adiposity measures. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence.

RESULTS

We included 169 trials (255 trial comparisons, n = 10,357) assessing 14 food sources at 4 energy control levels over a median 12 wk. Total fructose-containing sugars increased body weight (MD: 0.28 kg; 95% CI: 0.06, 0.50 kg; P_MD = 0.011) in addition trials and decreased body weight (MD: -0.96 kg; 95% CI: -1.78, -0.14 kg; P_MD = 0.022) in subtraction trials with no effect in substitution or ad libitum trials. There was interaction/influence by food sources on body weight: substitution trials [fruits decreased; added nutritive sweeteners and mixed sources (with SSBs) increased]; addition trials [dried fruits, honey, fruits (≤10%E), and 100% fruit juice (≤10%E) decreased; SSBs, fruit drink, and mixed sources (with SSBs) increased]; subtraction trials [removal of mixed sources (with SSBs) decreased]; and ad libitum trials [mixed sources (with/without SSBs) increased]. GRADE scores were generally moderate. Results were similar across secondary outcomes.

CONCLUSIONS

Energy control and food sources mediate the effect of fructose-containing sugars on adiposity. The evidence provides a good indication that excess energy from sugars (particularly SSBs at high doses ≥20%E or 100 g/d) increase adiposity, whereas their removal decrease adiposity. Most other food sources had no effect, with some showing decreases (particularly fruits at lower doses ≤10%E or 50 g/d). This trial was registered at clinicaltrials.gov as NCT02558920 (https://clinicaltrials.gov/ct2/show/NCT02558920).

Investigation of the association between serum uric acid levels and HEART risk score in patients with acute coronary syndrome

The association between uric acid (UA) and cardio-metabolic conditions has been recognized for a long time. However, recently, a body of evidence has highlighted the independent role of UA in a series of conditions, including renal and cardiovascular diseases. In this light, data regarding the prognostic role of UA in acute coronary syndrome (ACS) is scarce. A total number of 100 patients, 59 males and 41 females, diagnosed with ACS were recruited in this study. At the time of admission to the hospital, the serum level of UA was measured. In addition, the HEART score was calculated based on each patients' profile. Participants were on average 61.37 ± 12.08 years old. The most prevalent risk factors were hypertension (48%), a history of coronary artery disease (40%), and diabetes mellitus (33%). The average serum level of UA was 5.81 ± 1.81 mg/dl, and the calculated HEART score had a median of six (minimum of two and maximum of ten). A positive yet statistically insignificant correlation was found between the measured UA level and the calculated HEART score (R = 0.375, p = 0.090). However, further studies with larger sample size are required to assess the direct association of UA level with major adverse cardiac events in patients with cardiovascular disease.

Do thrifty genes exist? Revisiting uricase

Sixty years ago, the geneticist James Neel proposed that the epidemics of obesity and diabetes today may have evolutionary roots. Specifically, he suggested that our ancestors may have accumulated mutations during periods of famine that provided a survival advantage at that time. However, the presence of this "thrifty genotype" in today's world, where food is plentiful, would predispose us to obesity and diabetes. The "thrifty gene" hypothesis, attractive to some, has been challenged over the years. The authors have previously postulated that the loss of the uricase gene, resulting in a rise in serum and intracellular uric acid levels, satisfies the criteria of a thrifty genotype mutation. This paper reviews and brings up-to-date the evidence supporting the hypothesis and discusses the current arguments that challenge this hypothesis. Although further studies are needed to test the hypothesis, the evidence supporting a loss of uricase as a thrifty gene is substantial and supports a role for evolutionary biology in the pathogenesis of the current obesity and diabetes epidemics.

Lowering and Raising Serum Urate Levels: Off-Label Effects of Commonly Used Medications

Drug-induced hyperuricemia and gout present an increasingly prevalent problem in clinical practice. Herein, we review the urate-lowering or urate-raising effects of commonly used agents. We performed a PubMed search using the terms gout, urate, and medication, along with the specific agents/classes described herein. Reports were reviewed until 2022, and original studies were considered if they primarily or secondarily reported the effects of 1 or more drugs on serum urate level. Previous reviews were assessed for references to additional studies that described urate-altering effects of medications. Urate-changing drugs are summarized regarding their magnitude of effect, mechanism of action, and clinical significance. Potentially urate-lowering drugs include angiotensin II receptor blockers, calcium channel blockers, high-dose aspirin and salicylates, some nonsalicylate nonsteroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, sodium-glucose cotransporter 2 inhibitors, statins, and fenofibrate. Potentially urate-increasing drugs discussed include diuretics, β-blockers, insulin, pyrazinamide, ethambutol, calcineurin inhibitors, low-dose aspirin, testosterone, and lactate. In patients who have or are at risk for hyperuricemia or gout, an increased awareness of drugs that affect serum urate level may allow for prescribing that effectively treats the indicated problem while minimizing adverse effects on hyperuricemia and gout.

High versus low-added sugar consumption for the primary prevention of cardiovascular disease

BACKGROUND

High intake of added sugar have been suggested to impact the risk for cardiovascular disease (CVD). Knowledge on the subject can contribute to preventing CVD.

OBJECTIVES

To assess the effects of a high versus low-added sugar consumption for primary prevention of CVD in the general population.

SEARCH METHODS

We searched Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase, Conference Proceedings Citation Index-Science (CPCI-S) on 2 July 2021. We also conducted a search of ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) Search Portal for ongoing or unpublished trials. The search was performed together with reference checking, citation searching and contact with study authors to identify additional studies. We imposed no restriction on language of publication or publication status.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), including cross-over trials, that compared different levels of added sugar intake. Exclusion criteria were: participants aged below 18 years; diabetes mellitus (type 1 and 2); and previous CVD. Primary outcomes were incident cardiovascular events (coronary, carotid, cerebral and peripheral arterial disease) and all-cause mortality. Secondary outcomes were changes in systolic and diastolic blood pressure, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, fasting plasma glucose and adverse events (gastrointestinal symptoms and impaired dental health).

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 21 RCTs (1110 participants completing the interventions) examining the effects of different levels of added sugar intake with a mean duration of 14 weeks. The study participants were generally described as healthy and the mean age ranged from 22 to 57 years. No studies reported on cardiovascular events or all-cause mortality. There was minimal effect of low intake of added sugar on total cholesterol levels (MD 0.11, 95% CI 0.01 to 0.21; I² = 0%; 16 studies; 763 participants; low certainty of evidence) and triglycerides (MD 0.10, 95% CI 0.03 to 0.17; I² = 3%; 14 studies; 725 participants) but no evidence of effect on LDL-cholesterol and HDL-cholesterol. There was minimal effect on diastolic blood pressure (MD 1.52, 95% CI 0.67 to 2.37; I² = 0%; 13 studies; 873 participants) and on systolic blood pressure (MD 1.44, 95% 0.08 to 2.80; I² = 27%, 14 studies; 873 participants; low certainty of evidence), but no evidence of effect on fasting plasma glucose. Only one study reported on dental health, with no events. No other trials reported adverse events (impaired dental health or gastrointestinal symptoms). All results were judged as low-quality evidence according to GRADE. The risk of bias was generally unclear, five studies were classified at an overall low risk of bias (low risk in at least four domains, not including other bias).

AUTHORS' CONCLUSIONS

No trials investigating the effect of added sugar on cardiovascular events or all-cause mortality were identified in our searches. Evidence is uncertain whether low intake of added sugar has an effect on risk factors for CVD; the effect was small and the clinical relevance is, therefore, uncertain. Practical ways to achieve reductions in dietary added sugar includes following current dietary recommendations. Future trials should have longer follow-up time and report on all-cause mortality and cardiovascular events in order to clarify the effect of added sugar on these outcomes. Future trials should also aim for more direct interventions and preferably be more independent of industry funding.

Pathophysiological Mechanisms of Hypertension Development Induced by Fructose Consumption

During the past several decades, there has been a dramatic increase in fructose consumption worldwide in parallel with epidemics of metabolic diseases. Accumulating evidence has suggested that excessive fructose consumption...

Allopurinol to reduce cardiovascular morbidity and mortality: A systematic review and meta-analysis

Aims

To compare the effectiveness of allopurinol with no treatment or placebo for the prevention of cardiovascular events in hyperuricemic patients.

Methods and results

Pubmed, Web of Science and Cochrane library were searched from inception until July 2020. Randomized controlled trials (RCT) and observational studies in hyperuricemic patients without significant renal disease and treated with allopurinol, versus placebo or no treatment were included. Outcome measures were cardiovascular mortality, myocardial infarction, stroke, or a combined endpoint (CM/MI/S). For RCT’s a random effects meta-analysis was performed. For observational studies a narrative synthesis was performed. Of the original 1995 references we ultimately included 26 RCT’s and 21 observational studies. We found a significantly reduced risk of combined endpoint (Risk Ratio 0.65 [95% CI] [0.46 to 0.91]; p = 0.012) and myocardial infarction (RR 0.47 [0.27 to 0.80]; p = 0.01) in the allopurinol group compared to controls. We found no significant effect of allopurinol on stroke or cardiovascular mortality. Of the 15 observational studies with sufficient quality, allopurinol was associated with reduced cardiovascular mortality in 1 out of 3 studies that reported this outcome, myocardial infarction in 6 out of 8, stroke in 4 out of 7, and combined end-point in 2 out of 2. Cardiovascular benefit was only observed when allopurinol therapy was prolonged for more than 6 months and when an appropriate allopurinol dose was administered (300 mg or more/day) or sufficient reduction of serum urate concentration was achieved (<0.36 mmol/l).

Conclusions

Data from RCT’s and observational studies indicate that allopurinol treatment reduces cardiovascular risk in patients with hyperuricemia. However, the quality of evidence from RCTs is low to moderate. To establish whether allopurinol lowers the risk of cardiovascular events a well-designed and adequately powered randomized, placebo-controlled trial is needed in high-risk patients with hyperuricemia.

Systematic review registration

PROSPERO registration CRD42018089744

Different Food Sources of Fructose-Containing Sugars and Fasting Blood Uric Acid Levels: A Systematic Review and Meta-Analysis of Controlled Feeding Trials

BACKGROUND

Although fructose as a source of excess calories increases uric acid, the effect of the food matrix is unclear.

OBJECTIVES

To assess the effects of fructose-containing sugars by food source at different levels of energy control on uric acid, we conducted a systematic review and meta-analysis of controlled trials.

METHODS

MEDLINE, Embase, and the Cochrane Library were searched (through 11 January 2021) for trials ≥ 7 days. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars in diets); addition (excess energy from sugars added to diets); subtraction (energy from sugars subtracted from diets); and ad libitum (energy from sugars freely replaced in diets) designs. Independent reviewers (≥2) extracted data and assessed the risk of bias. Grading of Recommendations, Assessment, Development, and Evaluation was used to assess the certainty of evidence.

RESULTS

We included 47 trials (85 comparisons; N = 2763) assessing 9 food sources [sugar-sweetened beverages (SSBs), sweetened dairy, fruit drinks, 100% fruit juice, fruit, dried fruit, sweets and desserts, added nutritive sweetener, and mixed sources] across 4 energy control levels in predominantly healthy, mixed-weight adults. Total fructose-containing sugars increased uric acid levels in substitution trials (mean difference, 0.16 mg/dL;  95% CI:  0.06-0.27 mg/dL;  P = 0.003), with no effect across the other energy control levels. There was evidence of an interaction by food source: SSBs and sweets and desserts increased uric acid levels in the substitution design, while SSBs increased and 100% fruit juice decreased uric acid levels in addition trials. The certainty of evidence was high for the increasing effect of SSBs in substitution and addition trials and the decreasing effect of 100% fruit juice in addition trials and was moderate to very low for all other comparisons.

CONCLUSIONS

Food source more than energy control appears to mediate the effects of fructose-containing sugars on uric acid. The available evidence provides reliable indications that SSBs increase and 100% fruit juice decreases uric acid levels. More high-quality trials of different food sources are needed. This trial was registered at clinicaltrials.gov as NCT02716870.

Development, Implementation, and Evaluation of an Educational Package to Control the Biomedical Profile of Metabolic Syndrome

Background:

Unhealthy lifestyle behaviors are a major concern in the development of metabolic syndrome (MetS). This study aimed to develop, implement, and evaluate a lifestyle education package as a strategy to control the biomedical components of MetS

Methods:

A total of 72 women and men (aged 18–68 y) with MetS were selected through randomized sampling. They were classified into 2 groups: an intervention group that received a lifestyle educational package with close follow-ups and a control group that received only usual care. Anthropometric indices, blood pressure, lipid profiles, and fasting blood sugar were assessed at baseline and after 3 months.

Results:

The lifestyle-modification program was associated with a modest weight loss (2 ± 0.4 kg; P < 0.001), a significant reduction in waist circumference (2.3 ± 0.9 cm; P < 0.001) and the hip circumference (1 ± 0.3 cm; P < 0.001), and a sharp decrease in diastolic blood pressure (5.3 ± 1.4 mm Hg; P < 0.001), compared with the baseline values in the intervention group. Additionally, according to the one-way MANOVA analysis, 33.8% of the changes in MetS components were attributable to the educational intervention (P < 0.001, F = 5.27).

Conclusions:

Improvement in lipid profile and anthropometric measures suggest that a lifestyle package based on multivariable health education is an acceptable method.

Baseline and change in serum uric acid predict the progression from prehypertension to hypertension: a prospective cohort study

Evidence is lacking about the role of serum uric acid (SUA) in the progression from prehypertension to hypertension. Herein, we aimed to investigate the association of both baseline and dynamic change in SUA with the risk of hypertension developing from prehypertension. The study enrolled 11,488 participants with prehypertension during 2006-2010 from the Kailuan study. Change in SUA was assessed as % change of SUA from 2006 (baseline) to 2010. Participants were categorized into four groups by quartiles of baseline and change in SUA, separately. Multivariable logistic regressions were used to calculation the odds ratio (OR) and 95% confidence interval (CI). During a median follow-up of 7.06 years, 2716 (23.64%) participants developed hypertension from prehypertension. In the multivariable-adjusted model, the OR for hypertension comparing participants in the highest versus the lowest quartile of baseline SUA were 1.18 (95% CI, 1.02-1.36). Increased SUA over time was also associated with elevated risk of hypertension (OR in the highest quartile was 1.41 [95% CI, 1.23-1.62] versus the lowest quartile), especially in those with baseline SUA ≥ median (OR, 1.48; 95% CI, 1.21-1.81). Moreover, the addition of SUA to a conventional risk model had an incremental effect on the predictive value for hypertension (integrated discrimination improvement 0.30%, P < 0.0001; category-free net reclassification improvement 12.36%, P < 0.0001). Both high initial SUA and increased SUA over time can independently predict the progression from prehypertension to hypertension. Strategies aiming at controlling SUA level in prehypertensive subjects may impede the onset of hypertension.

U-Shaped Relationship Between Cardiovascular Mortality and Serum Uric Acid May Be Attributed to Stroke- and Heart-Specific Mortality, Respectively, Among Hypertensive Patients: A Nationally Representative Cohort Study

BACKGROUND Serum uric acid (UA) is involved in the development of hypertension. However, its impact on mortality in hypertension remains unclear. We aimed to assess the association of cardiovascular and all-cause mortality with UA in a hypertensive population. MATERIAL AND METHODS This study included 15 583 hypertensive patients from the NHANES study during 1999-2014. Weighted Cox regression analyses and cubic spline fitting were used to assess the relationship between UA and mortality risk. RESULTS Over a median follow-up of 7.4 years (116 351 person-years), a total of 3291 deaths occurred. Mortality was examined according to 5 predefined UA levels: £3.5, 3.5-5, 5-6, 6-7.5, and >7.5 mg/dL. In multivariable analysis with 5-6 mg/dL as a reference, the hazard ratios (95% confidence interval) of total mortality across the 5 groups were 1.40 (1.05-1.88), 1.08 (0.95-1.21), 1.00 (reference), 1.14 (1.02-1.29), and 1.74 (1.50-2.02), respectively. According to a restricted cubic spline, we noted a U-shaped relationship between UA and total mortality. The U-shaped relationship between UA and cardiovascular mortality remained in both females and males. The increased cardiovascular mortality in the lowest and highest UA groups was attributed to stroke and heart-specific mortality, respectively. However, serum UA was not significantly associated with cancer mortality. CONCLUSIONS Our findings showed a U-shaped relationship between serum UA levels and total and cardiovascular mortality in patients with hypertension. Furthermore, low UA was associated with stroke mortality, while higher UA was associated with heart-related mortality. Further research is needed to identify the potential mechanisms of UA in hypertension.

Association between relative fat mass, uric acid, and insulin resistance in children with chronic kidney disease

INTRODUCTION

This cross-sectional study investigates the association between insulin resistance (IR) and serum uric acid (sUA) and relative fat (RFM) and lean mass (RLM) profiles in children with chronic kidney disease (CKD).

MATERIAL AND METHODS

RLM and RFM were assessed by bioimpedance spectroscopy in 41 children and adolescents. Normal weight obesity (NWO) was defined as normal height-age body mass index and RFM >85th percentile, according to age and sex. Homeostatic model assessment of insulin resistance (HOMA-IR) level >95th percentile, according to sex and pubertal stage, and sUA >7 mg/dl were used to define IR and hyperuricemia, respectively.

RESULTS

High RFM (15 patients) and NWO (7 patients) were associated with higher HOMA-IR in total (p < 0.001) and normal-weight patients (p = 0.004), respectively. RFM was positively and RLM negatively correlated to HOMA-IR (rs = 0.500, p = 0.001 and rs = -0.539, p < 0.001, respectively) and sUA (rs = 0.370, p = 0.017 and rs = -0.325, p = 0.038, respectively), while sUA was positively correlated to HOMA-IR (rs = 0.337, p = 0.031). Hyperuricemia (16 patients) was positively associated with higher RFM and HOMA-IR (p = 0.001 and p = 0.010, respectively). The correlation between sUA and HOMA-IR lost significance after adjustment for RFM. In logistic regression analysis, a 5% increase in RFM was associated with IR (11 patients) independently of the age, sex, sUA, and CKD stage in both total (OR 2.174, 95% CI 1.115-4.225) and normal-weight (OR 3.504, 95% CI 1.110-11.123) patients.

CONCLUSION

Children with high RFM, including those presenting NWO, are at risk for IR regardless of CKD stage. RFM is probably the mediator of the link between sUA and IR.

Uric Acid and Hypertension: Prognostic Role and Guide for Treatment

The relationship between serum uric acid (SUA) and hypertension has been a subject of increasing interest since the 1870 discovery by Frederick Akbar Mahomed. Several epidemiological studies have shown a strong association between high SUA levels and the presence or the development of hypertension. Genetic analyses have found that xanthine oxidoreductase (XOR) genetic polymorphisms are associated with hypertension. However, genetic studies on urate transporters and Mendelian randomization studies failed to demonstrate a causal relationship between SUA and hypertension. Results from clinical trials on the role of urate-lowering therapy in the management of patients with hypertension are not uniform. Our study sought to analyze the prognostic and therapeutic role of SUA in the hypertensive disease, from uric acid (UA) biology to clinical trials on urate-lowering therapies.

Nutrition and microRNAs: Novel Insights to Fight Sarcopenia

Sarcopenia is a progressive age-related loss of skeletal muscle mass and strength, which may result in increased physical frailty and a higher risk of adverse events. Low-grade systemic inflammation, loss of muscle protein homeostasis, mitochondrial dysfunction, and reduced number and function of satellite cells seem to be the key points for the induction of muscle wasting, contributing to the pathophysiological mechanisms of sarcopenia. While a range of genetic, hormonal, and environmental factors has been reported to contribute to the onset of sarcopenia, dietary interventions targeting protein or antioxidant intake may have a positive effect in increasing muscle mass and strength, regulating protein homeostasis, oxidative reaction, and cell autophagy, thus providing a cellular lifespan extension. MicroRNAs (miRNAs) are endogenous small non-coding RNAs, which control gene expression in different tissues. In skeletal muscle, a range of miRNAs, named myomiRNAs, are involved in many physiological processes, such as growth, development, and maintenance of muscle mass and function. This review aims to present and to discuss some of the most relevant molecular mechanisms related to the pathophysiological effect of sarcopenia. Besides, we explored the role of nutrition as a possible way to counteract the loss of muscle mass and function associated with ageing, with special attention paid to nutrient-dependent miRNAs regulation. This review will provide important information to better understand sarcopenia and, thus, to facilitate research and therapeutic strategies to counteract the pathophysiological effect of ageing.

Pharmacotherapy for hyperuricaemia in hypertensive patients

BACKGROUND

This is the second update of this systematic review. High blood pressure represents a major public health problem. Worldwide, approximately one-fourth of the adult population has hypertension. Epidemiological and experimental studies suggest a link between hyperuricaemia and hypertension. Hyperuricaemia affects 25% to 40% of those with untreated hypertension; a much lower prevalence has been reported in those with normotension or in the general population. However, whether lowering serum uric acid (UA) might lower blood pressure (BP), is an unanswered question.

OBJECTIVES

To determine whether UA-lowering agents reduce BP in people with primary hypertension or prehypertension, compared with placebo.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to May 2020: the Cochrane Hypertension Specialised Register, CENTRAL 2018, Issue 12, MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched LILACS (1982 to May 2020), and contacted authors of relevant papers regarding further published and unpublished work. The searches had no language or date restrictions.

SELECTION CRITERIA

To be included in this updated review, the studies had to meet the following criteria: 1) randomised or quasi-randomised, with a group assigned to receive a UA-lowering agent and another group assigned to receive placebo; 2) double-blind, single-blind, or open-label; 3) parallel or cross-over trial design; 4) cross-over trials had to have a washout period of at least two weeks; 5) minimum treatment duration of four weeks; 6) participants had to have a diagnosis of essential hypertension or prehypertension plus hyperuricaemia (serum UA greater than 6 mg/dL in women, 7 mg/dL in men, and 5.5 mg/dL in children or adolescents); 7) outcome measures included change in 24-hour ambulatory systolic or diastolic BP, or both; or clinic-measured systolic or diastolic BP, or both.

DATA COLLECTION AND ANALYSIS

The two review authors independently collected the data using a data extraction form, and resolved any disagreements via discussion. We assessed risk of bias using the Cochrane 'Risk of bias' tool. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

In this review update, we screened 722 records, selected 26 full-text reports for evaluation. We identified no ongoing studies and did not add any new studies. We included three randomised controlled trials (RCTs), enrolling 211 people with hypertension or prehypertension, plus hyperuricaemia. Low-certainty evidence from three RCTs found inconclusive results between those who received UA-lowering drugs and placebo, in 24-hour ambulatory systolic (MD -6.2 mmHg, 95% CI -12.8 to 0.5) or diastolic BP (-3.9 mmHg, 95% CI -9.2 to 1.4). Low-certainty evidence from two RCTs found that UA-lowering drugs reduced clinic-measured systolic BP (-8.43 mmHg, 95% CI -15.24 to -1.62) but results for clinic-measured diastolic BP were inconclusive (-6.45 mmHg, 95% CI -13.60 to 0.70). High-certainty evidence from three RCTs found that serum UA levels were reduced by 3.1 mg/dL (95% CI 2.4 to 3.8) in the participants that received UA-lowering drugs. Low-certainty evidence from three RCTs found inconclusive results regarding the occurrence of adverse events between those who received UA-lowering drugs and placebo (RR 1.86, 95% CI 0.43 to 8.10).

AUTHORS' CONCLUSIONS

In this updated Cochrane Review, the current RCT data are insufficient to know whether UA-lowering therapy lowers BP. More studies are needed.

Effects of low fructose diet on glycemic control, lipid profile and systemic inflammation in patients with type 2 diabetes: A single-blind randomized controlled trial

BACKGROUND AND AIM

Type 2 diabetes is one of the global epidemic disorders, which causes many side effects on the body. Fructose is a lipogenic monosaccharide. Recent studies have reported the adverse effects of this carbohydrate on diabetes. This study aimed to evaluate the clinical efficacy of a low-fructose diet on the metabolic alterations in patients with type 2 diabetes.

METHODS

This study was a randomized, single-blind clinical trial on 50 patients with type 2 diabetes. Participants randomly allocated to two groups, to receive either diabetic-diet or diabetic-diet with low-fructose for 8-weeks. Anthropometric measurements, systolic blood pressure (SBP), Diastolic blood pressure (DBP) and metabolic factors were assessed at baseline and the end of the trial.

RESULTS

At the end of trial, reduction in body weight, waist circumference, and blood pressure were not significant except for DBP (P = 0.013). Statistical analysis showed that low-fructose diet compared to control group significantly declined fasting blood glucose (FBG), Hemoglobin A1c (HbA1c), Triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C) and high-sensitivity C-reactive protein (hs-CRP) (P = 0.015, P = 0.001, P=<0.0001, P= <0.0001 and P= <0.0001 respectively).

CONCLUSION

Our results showed that eight weeks of low-fructose diet results in a significant improvement in FBG, HbA1c, TG, HDL-C and hs-CRP in patients with type 2 diabetes.

Confounded by obesity and modulated by urinary uric acid excretion, sleep-disordered breathing indirectly relates to hyperuricaemia in males: A structural equation model

Sleep-disordered breathing (SDB) causes hypoxic stress and can trigger uric acid (UA) overproduction. We comprehensively investigated whether SDB, interacting with components of metabolic syndrome, hepatic and renal dysfunctions, low physical fitness, sedentary lifestyle, disrupted sleep, and chronic systemic inflammation (CSI), is directly associated with hyperuricaemia. In 528 community-based males (mean [SD] age 46.2 [7.4] years), we cross-sectionally analysed measures of anthropometry; self-reported lifestyle habits; overnight sleep polysomnography data; cardiopulmonary exercise tests; and biomarkers of cardiometabolic, hepatic, and renal functions; and CSI, using structural equation modelling. Objective disrupted sleep, C-reactive protein, low physical fitness, and sedentary lifestyle were not related to UA levels in univariate analysis and were excluded. The latent variables (with corresponding manifest variables) obesity (body mass index, waist-hip ratio), hypertension (post-sleep systolic, diastolic blood pressure), dyslipidaemia (total cholesterol, triglyceride/high-density lipoprotein cholesterol), hepatic dysfunction (alanine aminotransferase, aspartate transaminase), and renal dysfunction (blood urea nitrogen, serum creatinine) were positively; and hyperglycaemia (fasting glucose, glycated haemoglobin) was negatively associated with hyperuricaemia (serum UA), except for SDB (Apnea-Hypopnea Index, percentage of oxygen saturation <90% period against total sleep time, oxygen desaturation index) in the one-stage influence model. In the two-stage model, SDB, closely interacting with obesity, was positively indirectly associated with hyperuricaemia through directly linked renal dysfunction and obesity-linked hypertension, inverse hyperglycaemia, dyslipidaemia, and hepatic dysfunction. In conclusion, structural equation modelling reveals that SDB closely interacts with obesity and is positively but indirectly related to hyperuricaemia in males. This suggests that urinary UA excretion modulates and obesity confounds the SDB-hyperuricaemia relationship.

Uric Acid and Hypertension: An Update With Recommendations

The association between increased serum urate and hypertension has been a subject of intense controversy. Extracellular uric acid drives uric acid deposition in gout, kidney stones, and possibly vascular calcification. Mendelian randomization studies, however, indicate that serum urate is likely not the causal factor in hypertension although it does increase the risk for sudden cardiac death and diabetic vascular disease. Nevertheless, experimental evidence strongly suggests that an increase in intracellular urate is a key factor in the pathogenesis of primary hypertension. Pilot clinical trials show beneficial effect of lowering serum urate in hyperuricemic individuals who are young, hypertensive, and have preserved kidney function. Some evidence suggest that activation of the renin-angiotensin system (RAS) occurs in hyperuricemia and blocking the RAS may mimic the effects of xanthine oxidase inhibitors. A reduction in intracellular urate may be achieved by lowering serum urate concentration or by suppressing intracellular urate production with dietary measures that include reducing sugar, fructose, and salt intake. We suggest that these elements in the western diet may play a major role in the pathogenesis of primary hypertension. Studies are necessary to better define the interrelation between uric acid concentrations inside and outside the cell. In addition, large-scale clinical trials are needed to determine if extracellular and intracellular urate reduction can provide benefit hypertension and cardiometabolic disease.

Serum uric acid in Korean children and adolescents: reference percentiles and association with metabolic syndrome

PURPOSE

To establish age/sex-specific reference intervals for serum uric acid and to examine the associations between serum uric acid level and metabolic syndrome (MetS) and its components in Korean children and adolescents.

METHODS

We analyzed data for 1,349 subjects aged 10 to 19 years from the Korea National Health and Nutrition Examination Survey 2016-2017.

RESULTS

The mean uric acid levels were 5.9±1.3 mg/dL (interquartile range, 5.0-6.8 mg/dL) in males and 4.6±0.9 mg/dL (interquartile range, 3.9-5.2 mg/dL) in females. The mean uric acid level increased significantly from 10-13 years of age in males, but not in females. The overall prevalence of MetS was 5.9% (7.3% in males and 4.3% in females; P=0.022). The prevalences of MetS in the lowest, second, third, and highest quartiles of uric acid level were 4.4%, 3.3%, 6.1%, and 15.2%, respectively, in males (P for trend &lt;0.001) and 1.9%, 0.0%, 4.1%, and 10.9%, respectively, in females (P for trend &lt;0.001). Compared with the lowest quartile of uric acid level, the odds ratio (with 95% confidence interval) for MetS in the highest quartile was 2.897 (1.140-7.361) in males and 5.173 (1.459-18.342) in females. Subjects in the highest quartile exhibited increased risk for abdominal obesity and low high-density lipoprotein cholesterol in both sexes.

CONCLUSION

Serum uric acid level is positively associated with MetS and its components abdominal obesity and low high-density lipoprotein cholesterol.

Hyperuricemia and Hypertension: Links and Risks

Hyperuricemia has long been recognized to be associated with increased cardiovascular risk, including risk of developing hypertension. Epidemiological findings suggest that the link with hypertension is stronger in children and adolescents. Uric acid acts as a strong antioxidant compound in the extracellular environment but has pro-inflammatory effects within the intracellular setting. A chronic phase of microvascular injury is known to occur after prolonged periods of hyperuricemia. This is proposed to contribute to afferent arteriolopathy and elevation of blood pressure that may become unresponsive to uric acid-lowering therapies over time. Studies have struggled to infer direct causality of hyperuricemia due to a vast number of confounders including body mass index. The aim of this review is to present the available data and highlight the need for large scale prospective randomized controlled trials in this area. At present, there is limited evidence to support a role for uric acid-lowering therapies in helping mitigate the risk of hypertension.

Does obesity modify the epidemiological association between hyperuricemia and the prevalence of hypertension among Northern Chinese community-dwelling people? A Chinese population-based study

OBJECTIVES

Hyperuricemia and obesity both play a role in the development of hypertension. However, limited evidence is available for the combined effect of hyperuricemia and obesity on the prevalence of hypertension in the Chinese population. We aimed to assess the separate and combined effects of these two risk factors on the risk of hypertension.

METHODS

We conducted a cross-sectional study in an area of Dalian city, Liaoning Province, China, from September 2015 to November 2016; 8700 adult residents were invited to participate in this study. Hyperuricemia was defined as serum uric acid ≥ 416 μmol/L in men and ≥ 357 μmol/L in women according to the guidelines. Individuals were categorised into four groups: the control group (body mass index (BMI) §amp;lt; 25 without hyperuricemia, the reference group), the obesity group (BMI ≥ 25 without hyperuricemia), the hyperuricemia group (BMI §amp;lt; 25 with hyperuricemia) and the obese-hyperuricemia group (BMI ≥ 25 with hyperuricemia). A multivariable logistic model was used to investigate individual and combined effects of hyperuricemia and obesity on the risk of hypertension.

RESULTS

Of the 8331 individuals included, 44.3% were obese, 13.6% suffered from hyperuricemia, and 7.8% were both obese and hyperuricemic. The hypertension prevalence was the highest in the obese-hyperuricemia group (55.5% (95% CI 51.6% to 59.2%)), followed by that in the obesity (44.3% (42.6% to 46.1%)) and that in the hyperuricemia groups (33.5% (29.5% to 37.9%)). After adjusting for confounders, the obese-hyperuricemia group had a nearly threefold increased risk of hypertension compared with their healthy counterparts (OR 2.98 (2.48 to 3.57)). This pattern was also observed in the obesity group with a higher risk of hypertension (OR 2.18 (1.96 to 2.42)) compared with the control group, whereas the risk of hypertension was not elevated significantly in the hyperuricemia group (OR 1.14 (0.92 to 1.42)).

CONCLUSION

Our study provided the first evidence that obese Chinese individuals with hyperuricemia had a significantly increased risk of hypertension compared with their healthy counterparts. This combined effect on the risk of hypertension is much stronger than the individual effect of either factor.

Allopurinol Prevents the Lipogenic Response Induced by an Acute Oral Fructose Challenge in Short-Term Fructose Fed Rats

We investigated whether short term high fructose intake may induce early hepatic dysfunction in rats and to test whether allopurinol treatment may have beneficial effects. Twenty male Sprague-Dawley rats received 20% fructose in drinking water (10 treated with allopurinol and 10 received vehicle) and 10 control rats received tap water. After 14 days, the hepatic response to an acute fructose load was evaluated, and in fasted animals, respirometry studies in freshly isolated mitochondria were performed. In fasting rats, we did not find differences in systemic or hepatic uric acid and triglyceride concentrations among the groups, but mitochondrial respiratory control rate was significantly decreased by high fructose feeding and correlated with a reduced expression of Complex I, as well as decreased aconitase-2 activity. On the other hand, in fructose fed rats, an acute fructose load increased systemic and hepatic uric acid, triglycerides and oxidative stress. Fructose feeding was also associated with fructokinase and xanthine oxidase overexpression and increased liver de novo lipogenesis program (fatty acid synthase (FAS) and cell death-inducing DFFA-like effector C (CIDEC) overexpression, ATP citrate lyase (ACL) and acetyl coA carboxylase (ACC) overactivity and decreased AMP-activated protein kinase (AMPk) and endothelial nitric oxide synthase (eNOS) activation). Allopurinol treatment prevented hepatic and systemic alterations. These data suggest that early treatment with xanthine oxidase inhibitors might provide a therapeutic advantage by delaying or even halting the progression of non-alcoholic fatty liver disease (NAFLD).

Hyperuricemia, Acute and Chronic Kidney Disease, Hypertension, and Cardiovascular Disease: Report of a Scientific Workshop Organized by the National Kidney Foundation

Urate is a cause of gout, kidney stones, and acute kidney injury from tumor lysis syndrome, but its relationship to kidney disease, cardiovascular disease, and diabetes remains controversial. A scientific workshop organized by the National Kidney Foundation was held in September 2016 to review current evidence. Cell culture studies and animal models suggest that elevated serum urate concentrations can contribute to kidney disease, hypertension, and metabolic syndrome. Epidemiologic evidence also supports elevated serum urate concentrations as a risk factor for the development of kidney disease, hypertension, and diabetes, but differences in methodologies and inpacts on serum urate concentrations by even subtle changes in kidney function render conclusions uncertain. Mendelian randomization studies generally do not support a causal role of serum urate in kidney disease, hypertension, or diabetes, although interpretation is complicated by nonhomogeneous populations, a failure to consider environmental interactions, and a lack of understanding of how the genetic polymorphisms affect biological mechanisms related to urate. Although several small clinical trials suggest benefits of urate-lowering therapies on kidney function, blood pressure, and insulin resistance, others have been negative, with many trials having design limitations and insufficient power. Thus, whether uric acid has a causal role in kidney and cardiovascular diseases requires further study.

Elevated serum uric acid predicts the development of moderate coronary artery calcification independent of conventional cardiovascular risk factors

BACKGROUND AND AIMS

Hyperuricemia was frequently noted in subjects with a high risk of cardiovascular disease (CVD). This study aimed to elucidate whether serum uric acid (SUA) is associated with development of moderate coronary artery calcification in generally healthy adults.

METHODS

A total of 9297 subjects underwent multidetector CT for the evaluation of CAC at least two times during their annual health examinations. Among them, 4461 participants without CVD history and who had no (scores 0) or minimal CAC (scores 1-10) in their first examination were enrolled. The association between SUA as a continuous and categorical variable and development of moderate coronary artery calcification (CAC score > 100) was assessed by Cox regression analysis. Receiver-operating characteristic (ROC) curves were constructed to investigate the diagnostic efficacy of SUA.

RESULTS

During a median follow-up of 4.1 years, 131 incident cases of moderate calcification developed. Baseline SUA concentration was significantly higher in subjects with progression to moderate coronary artery calcification (6.6 ± 1.3 vs. 5.8 ± 1.3 mg/dL, p < 0.001). SUA as a continuous variable (per 1 mg/dL) and divided into quartiles was positively associated with a higher risk of development of moderate calcification after adjustment for conventional CVD risk factors. The addition of SUA to the conventional CVD risk factors improved the predictive power for development of moderate coronary artery calcification.

CONCLUSIONS

SUA was an independent predictor for development of moderate coronary artery calcification in subjects with no or minimal calcification.

Uric Acid Is a Strong Risk Marker for Developing Hypertension From Prehypertension: A 5-Year Japanese Cohort Study

Prehypertension frequently progresses to hypertension, a condition associated with high morbidity and mortality from cardiovascular diseases and stroke. However, the risk factors for developing hypertension from prehypertension remain poorly understood. We conducted a retrospective cohort study using the data from 3584 prehypertensive Japanese adults (52.1±11.0 years, 2081 men) found to be prehypertensive in 2004 and reexamined in 2009. We calculated the cumulative incidences of hypertension over 5 years, examined risk factors, and calculated odds ratios (ORs) for developing hypertension after adjustments for age, sex, body mass index, smoking and drinking habits, baseline systolic and diastolic blood pressure, pulse rate, diabetes mellitus, dyslipidemia, chronic kidney disease, and serum uric acid levels. The additional analysis evaluated whether serum uric acid (hyperuricemia) constituted an independent risk factor for developing hypertension. The cumulative incidence of hypertension from prehypertension over 5 years was 25.3%. There were no significant differences between women and men (24.4% versus 26.0%; P=0.28). The cumulative incidence of hypertension in subjects with hyperuricemia (n=726) was significantly higher than those without hyperuricemia (n=2858; 30.7% versus 24.0%; P<0.001). After multivariable adjustments, the risk factors for developing hypertension from prehypertension were age (OR, 1.023; P<0.001), female sex (OR, 1.595; P<0.001), higher body mass index (OR, 1.051; P<0.001), higher baseline systolic (OR, 1.072; P<0.001) and diastolic blood pressure (OR, 1.085; P<0.001), and higher serum uric acid (OR, 1.149; P<0.001). Increased serum uric acid is a strong risk marker for developing hypertension from prehypertension. Further studies are needed to determine whether treatment of hyperuricemia in prehypertensive subjects could impede the onset of hypertension.

Serum uric acid levels are associated with homeostasis model assessment in obese nondiabetic patients: HOMA and uric acid

BACKGROUND

Hyperuricemia leads to insulin resistance, whereas insulin resistance decreases renal excretion of uric acid. The aim of this study was to evaluate whether there is a correlation between serum uric acid levels with homeostatic model assessment (HOMA) 1 in nondiabetic patients.

METHODS

We evaluated 88 nondiabetic patients, in whom uric acid levels were measured, in all of them HOMA of β-cell function (HOMA 1B) and HOMA of insulin resistance (HOMA 1IR) scores were performed. Uric acid and the HOMA 1 values were correlated using the Pearson coefficient.

RESULTS

We did not find any correlation between uric acid levels with both HOMA 1B (r = 0.102, p = 0.343), nor with HOMA 1IR (r = 0.158, p = 0.117). When patients were analyzed by sex, we found a significant correlation with HOMA 1IR (0.278, p = 0.01), but not with HOMA 1B (0.138, p = 0.257) in women. We found a correlation with HOMA 1B in men (r = 0.37, p = 0.044), but not with HOMA 1IR: 0.203, p = 0.283. The analysis performed based on body mass index did not show correlation in the patients with normal weight, (HOMA 1B r = 0.08, p = 0.5, HOMA 1IR = 0.034, p = 0.793), nor in the patients who were overweight (HOMA 1B: r = 0.05, p = 0.76, HOMA 1IR r = 0.145, p = 0.43). However, a significant correlation between uricemia with both HOMA 1B (0.559, p < 0.001), and HOMA 1IR (0.326, p < 0.05), was observed in obese patients.

CONCLUSION

Our results suggest that serum uric acid levels seem to be associated with insulin resistance in women, and in obese patients, but not in nonobese men. Uric acid also modifies β-cell function in men and in obese patients.

Uric acid in the pathogenesis of metabolic, renal, and cardiovascular diseases: A review

The association between uric acid (UA) on one side and systemic hypertension (Htn), dyslipidemia, glucose intolerance, overweight, fatty liver, renal disease and cardiovascular disease (CVD) on the other side is well recognized. However, the causal relationship between UA and these different clinical problems is still debatable. The recent years have witnessed hundreds of experimental and clinical trials that favored the opinion that UA is a probable player in the pathogenesis of these disease entities. These studies disclosed the strong association between hyperuricemia and metabolic syndrome (MS), obesity, Htn, type 2 diabetes mellitus (DM), non-alcoholic fatty liver disease, hypertriglyceridemia, acute kidney injury, chronic kidney disease (CKD), coronary heart disease (CHD), heart failure and increased mortality among cardiac and CKD patients. The association between UA and nephrolithiasis or preeclampsia is a non-debatable association. Recent experimental trials have disclosed different changes in enzyme activities induced by UA. Nitric oxide (NO) synthase, adenosine monophosphate kinase (AMPK), adenosine monophosphate dehydrogenase (AMPD), and nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase are affected by UA. These changes in enzymatic activities can lead to the observed biochemical and pathological changes associated with UA. The recent experimental, clinical, interventional, and epidemiologic trials favor the concept of a causative role of UA in the pathogenesis of MS, renal, and CVDs.

Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review

There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.

Pharmacotherapy for hyperuricemia in hypertensive patients

BACKGROUND

High blood pressure represents a major public health problem. Worldwide, approximately one-fourth of the adult population has hypertension. Epidemiological and experimental studies suggest a link between hyperuricemia and hypertension. Hyperuricemia affects 25% to 40 % of individuals with untreated hypertension; a much lower prevalence has been reported in normotensives or in the general population. However, whether lowering serum uric acid (UA) might lower blood pressure (BP) is an unanswered question.

OBJECTIVES

To determine whether UA-lowering agents reduce BP in patients with primary hypertension or prehypertension compared with placebo.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to February 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 2), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched LILACS up to March 2016 and contacted authors of relevant papers regarding further published and unpublished work.

SELECTION CRITERIA

To be included in this review, the studies had to meet the following criteria: 1) randomized or quasi-randomized, with a group assigned to receive a UA-lowering agent and another group assigned to receive placebo; 2) double-blind, single-blind or open-label; 3) parallel or cross-over trial; 4) cross-over trials had to have a washout period of at least two weeks; 5) minimum treatment duration of four weeks; 6) participants had to have a diagnosis of essential hypertension or prehypertension, and hyperuricemia (serum UA greater than 6 mg/dL in women, 7 mg/dL in men and 5.5 mg/dL in children/adolescents); 7) outcome measures assessed included change in clinic systolic, diastolic or 24-hour ambulatory BP.

DATA COLLECTION AND ANALYSIS

The two review authors independently collected the data using a data extraction form, and resolved any disagreements via discussion. We assessed risk of bias using the Cochrane Collaboration' Risk of bias' tool.

MAIN RESULTS

In this review update, we examined the abstracts of 349 identified papers and selected 21 for evaluation. We also identified three ongoing studies, the results of which are not yet available. Three other randomized controlled trials (RCTs) (two new), enrolling individuals with hypertension or prehypertension, and hyperuricemia, met the inclusion criteria for the review and were included in the meta-analysis. Low quality of evidence from three RCTs indicate no reduction in systolic (MD -6.2 mmHg, 95% CI -12.8 to 0.5) or diastolic (-3.9 mmHg, 95% CI -9.2 to 1.4) 24-hour ambulatory BP with UA-lowering drugs compared with placebo. Low quality of evidence from two RCTs reveal a reduction of systolic clinic BP (-8.43 mmHg, 95% CI -15.24 to -1.62) but not diastolic clinic BP (-6.45 mmHg, 95% CI -13.60 to 0.70). High quality of evidence from three RCTs indicates that serum UA levels were reduced by 3.1 mg/dL (95% CI 2.4 to 3.8) in the participants that received UA-lowering drugs. Very low quality of evidence from three RCTs suggests that withdrawals due to adverse effects were not increased with UA-lowering therapy (RR 1.86, 95% CI 0.43 to 8.10).

AUTHORS' CONCLUSIONS

In this updated systematic review, the RCT data available at present are insufficient to know whether UA-lowering therapy also lowers BP. More studies are needed.

The Role of Uric Acid in Hypertension of Adolescents, Prehypertension and Salt Sensitivity of Blood Pressure

Uric acid is the end product of purine metabolism. Metabolic disorders of uric acid are associated with many disease states. Substantial evidence suggests the possible role of uric acid as a mediator of high blood pressure. Elevated uric acid is closely associated with new onset essential hypertension in adolescents and prehypertension; and urate-lowering agents can significantly improve these early stages of hypertension. Uric acid also influences salt sensitivity of blood pressure through two phases. Local renin-angiotensin-aldosterone system activation initiates renal damage, arteriolopathy, and endothelium dysfunction, which is followed by the dysregulation of sodium homeostasis, thereby leading to increased salt sensitivity. In this review we summarize the available evidence to contribute to a better understanding of the casual relationship between uric acid and early or intermediate stages of hypertension. We hope our review can contribute to the prevention of hypertension or provide new insights into a treatment that would slow the progression of hypertension.

Effect of Restriction of Foods with High Fructose Corn Syrup Content on Metabolic Indices and Fatty Liver in Obese Children

OBJECTIVE

We examined the effect of restriction of foods with high fructose content in obese school children.

METHODS

In a clinical study, we selected 54 obese children 6 to 11 years old with high fructose consumption (>70 g/day) in order indicate dietary fructose restriction (<20 g/day) for 6 weeks. Anthropometry, liver ultrasound as well as glucose, insulin, lipids, leptin, IGFBP1, and RBP4 serum levels were collected.

RESULTS

The group of children had 80% adherence and reported decreased fructose consumption (110 ± 38.6 to 11.4 ± 12.0 g/day) and also a significant decrease in caloric (2,384 ± 568 to 1,757 ± 387 kcal/day) and carbohydrate consumption (302 ± 80.4 to 203 ± 56.0 g/day). The severity of steatosis improved significantly after fructose restriction (p < 0.000001). However, no changes in BMI, systolic blood pressure, or diastolic blood pressure were found. Only triglyceride levels decreased (1.44 ± 0.43 to 1.31 ± 0.38 mmol/l), High-densitiy lipoprotein cholesterol showed a marginal increase (1.45 ± 0.19 to 1.56 ± 0.44 mmol/l). Insulin resistance and RBP4 did not change.

CONCLUSIONS

In school children, the restriction of high fructose foods with a decrease of caloric and carbohydrate intake at 6 weeks did not induce weight loss; however, triglyceride levels and hepatic steatosis decreased. Differences with other studies in regard to weight loss may be explained by adaptive changes on metabolic expenditure.

New Pathogenic Concepts and Therapeutic Approaches to Oxidative Stress in Chronic Kidney Disease

In chronic kidney disease inflammatory processes and stimulation of immune cells result in overproduction of free radicals. In combination with a reduced antioxidant capacity this causes oxidative stress. This review focuses on current pathogenic concepts of oxidative stress for the decline of kidney function and development of cardiovascular complications. We discuss the impact of mitochondrial alterations and dysfunction, a pathogenic role for hyperuricemia, and disturbances of vitamin D metabolism and signal transduction. Recent antioxidant therapy options including the use of vitamin D and pharmacologic therapies for hyperuricemia are discussed. Finally, we review some new therapy options in diabetic nephropathy including antidiabetic agents (noninsulin dependent), plant antioxidants, and food components as alternative antioxidant therapies.

Cinnamaldehyde and allopurinol reduce fructose-induced cardiac inflammation and fibrosis by attenuating CD36-mediated TLR4/6-IRAK4/1 signaling to suppress NLRP3 inflammasome activation

Fructose consumption induces metabolic syndrome to increase cardiovascular disease risk. Cinnamaldehyde and allopurinol possess anti-oxidative and anti-inflammatory activity to relieve heart injury in metabolic syndrome. But the mechanisms of fructose-induced cardiac injury, and cardioprotective effects of cinnamaldehyde and allopurinol are not completely understood. In this study, fructose-fed rats displayed metabolic syndrome with elevated serum ox-LDL, cardiac oxidative stress, inflammation and fibrosis. Scavenger receptor CD36, Toll-like receptor 4 (TLR4), TLR6, IL-1R-associated kinase 4/1 (IRAK4/1), nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome, interleukin-1β, transforming growth factor-β (TGF-β), drosophila mothers against DPP homolog (Smad) 2/3 phosphorylation and Smad4 were increased in animal and H9c2 cell models. These pathological processes were further evaluated in ox-LDL or fructose-exposed H9c2 cells pretreated with ROS scavenger and CD36 specific inhibitor, or IRAK1/4 inhibitor, and transfected with CD36, NLRP3, or IRAK4/1 siRNA, demonstrating that NLPR3 inflammasome activation through CD36-mediated TLR4/6-IRAK4/1 signaling may promote cardiac inflammation and fibrosis. Cinnamaldehyde and allopurinol reduced cardiac oxidative stress to suppress NLPR3 inflammasome activation and TGF-β/Smads signaling by inhibiting CD36-mediated TLR4/6-IRAK4/1 signaling under fructose induction. These results suggest that the blockage of CD36-mediated TLR4/6-IRAK4/1 signaling to suppress NLRP3 inflammasome activation by cinnamaldehyde and allopurinol may protect against fructose-induced cardiac inflammation and fibrosis.

Fructose surges damage hepatic adenosyl-monophosphate-dependent kinase and lead to increased lipogenesis and hepatic insulin resistance

Fructose may be a key contributor to the biochemical alterations which promote the metabolic syndrome (MetS), non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2DM): (a) its consumption in all forms but especially in liquid form has much increased alongside with incidence of MetS conditions; (b) it is metabolized almost exclusively in the liver, where it stimulates de novo lipogenesis to drive hepatic triglyceride (TG) synthesis which (c) contributes to hepatic insulin resistance and NAFLD (Lustig et al., 2015; Weiss et al., 2013; Lim et al., 2010; Schwarzet al., 2015; Stanhope et al., 2009, 2013) [1-6]. The specifics of fructose metabolism and its main location in the liver serve to explain many of the possible mechanisms involved. It also opens questions, as the consequences of large increases in fructose flux to the liver may wreak havoc with the regulation of metabolism and would produce two opposite effects (inhibition and activation of AMP dependent kinase-AMPK) that would tend to cancel each other. We posit that (1) surges of fructose in the portal vein lead to increased unregulated flux to trioses accompanied by unavoidable methylglyoxal (MG) production, (2) the new, sudden flux exerts carbonyl stress on the three arginines on the γ subunits AMP binding site of AMPK, irreversible blocking some of the enzyme molecules to allosteric modulation, (3) this explains why, even when fructose quick phosphorylation increases AMP and should therefore activate AMPK, the effects of fructose are compatible with inactivation of AMPK, which then solves the apparent metabolic paradox. We put forward the hypothesis that fructose loads, via the increase in MG flux worsens the fructose-driven metabolic disturbances that lead to unrestricted de novo lipogenesis, fatty liver and hepatic insulin resistance. It does so via the silencing of AMPK. Our hypothesis is testable and if proven correct will shed some further light on fructose metabolism in the liver. It will also open new roads in glycation research, as modulation of MG catabolism may be a way to dampen the damage. Research on this area may have important therapeutic potential, e.g., more momentum to find new and improved carbonyl quenchers, new insights on the action of metformin, more evidence for the role of GAPDH inactivation due to mitochondrial overload in diabetes complications. AMPK plays a central role in metabolism, and its function varies in different tissues. For that reason, synthetic activators will always stumble with unwanted or unpredictable effects. Preventing MG damage on the protein could be a safer therapeutic avenue.

Uric acid and transforming growth factor in fructose-induced production of reactive oxygen species in skeletal muscle

The consumption of fructose, a major constituent of the modern diet, has raised increasing concern about the effects of fructose on health. Research suggests that excessive intake of fructose (>50 g/d) causes hyperuricemia, insulin resistance, mitochondrial dysfunction, de novo lipogenesis by the liver, and increased production of reactive oxygen species (ROS) in muscle. In a number of tissues, uric acid has been shown to stimulate the production of ROS via activation of transforming growth factor β1 and NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 4. The role of uric acid in fructose-induced production of ROS in skeletal muscle, however, has not been investigated. This review examines the evidence for fructose-induced production of ROS in skeletal muscle, highlights proposed mechanisms, and identifies gaps in current knowledge.

Uric acid in metabolic syndrome: From an innocent bystander to a central player

Uric acid, once viewed as an inert metabolic end-product of purine metabolism, has been recently incriminated in a number of chronic disease states, including hypertension, metabolic syndrome, diabetes, non-alcoholic fatty liver disease, and chronic kidney disease. Several experimental and clinical studies support a role for uric acid as a contributory causal factor in these conditions. Here we discuss some of the major mechanisms linking uric acid to metabolic and cardiovascular diseases. At this time the key to understanding the importance of uric acid in these diseases will be the conduct of large clinical trials in which the effect of lowering uric acid on hard clinical outcomes is assessed. Elevated uric acid may turn out to be one of the more important remediable risk factors for metabolic and cardiovascular diseases.