Uric acid: a danger signal from the RNA world that may have a role in the epidemic of obesity, metabolic syndrome, and cardiorenal disease: evolutionary considerations

The positive association between hyperuricemia and polycystic ovary syndrome and analysis of related factors

Purpose

To examine the potential association between polycystic ovary syndrome (PCOS) and hyperuricemia and to elucidate the underlying contributory factors.

Methods

Retrospective study on 603 women with PCOS and 604 women without PCOS. Anthropometric features, reproductive hormone profiles, and metabolic parameters were measured and compared between two groups of patients. Examinations of correlations between SUA levels and other parameters were conducted to discern potential correlations.

Results

Both serum uric acid levels and the incidence of hyperuricemia exhibited statistically significant elevations in women with PCOS when compared to their counterparts without PCOS. Nonetheless, this statistical difference was not found between the obese subgroup after stratifying study subjects by body mass index (BMI). Pearson's correlation analysis underscored the prominence of BMI as a robust factor influencing SUA levels in women, regardless of their PCOS status. Furthermore, multivariable linear regression model demonstrated significant positive associations between SUA levels and several variables, namely dehydroepiandrosterone sulfate (DHEA-S), free androgen index (FAI), total cholesterol (TC), triglycerides (TG), free fatty acids (FFA), fasting insulin (FINS), homeostatic model assessment of insulin resistance (HOMA-IR), area under the curve for insulin (AUC-I), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Additionally, it is noteworthy that the prevalence of hyperuricemia exhibited a positive association with fasting plasma glucose (FPG) levels, while conversely, it displayed a negative association with estradiol (E2) levels.

Conclusions

PCOS is associated with a significant elevation of SUA level and hyperuricemia prevalence. HA, IR, and dyslipidemia may be the mediators in the pathogenesis of hyperuricemia in women with PCOS.

Association between serum uric acid-to-high-density lipoprotein cholesterol ratio and insulin resistance in an American population: A population-based analysis

INTRODUCTION

Previous studies have demonstrated a correlation between the serum uric acid-to-high-density lipoprotein cholesterol ratio (UHR) and insulin resistance (IR) in individuals with type 2 diabetes mellitus. However, no existing studies have investigated the relationship between IR and UHR in the general population. Therefore, the primary objective of this study was to investigate the correlation between UHR and IR in the general American population.

METHODS

A sample of 8,817 participants was selected from the 2013 to 2020 National Health and Nutrition Examination Survey (NHANES). Homeostatic model assessment of insulin resistance (HOMA-IR) was used to assess insulin resistance. Multiple logistic regression, generalized smooth curve fitting, and subgroup analysis were used to assess the association between IR and UHR.

RESULTS

Multiple logistic regression analysis indicated a significant correlation between insulin resistance and UHR, with odds ratios (OR) of 1.07 (95% CI = 1.03-1.11) in males and 1.18 (95% CI = 1.13-1.25) in females. A non-linear relationship and saturation effect between IR risk and UHR were observed, characterized by an inverted L-shaped curve and a critical inflection point at 8.82. It was found that the area under the ROC curve (AUC) of UHR was significantly larger (AUC = 0.703 for males and 0.747 for females, all P < 0.01) compared with the use of UA or HDL-C alone. Subgroup analysis showed that this independent association remain consistent regardless of race, age, BMI, diabetes, moderate activities, education level, alcohol drinking, and gender.

CONCLUSION

Elevated UHR demonstrates a significant correlation with insulin resistance, so it can be used as a potential indicator of insulin resistance within the American population.

Current trends and possibilities of typical microbial protein production approaches: a review

Global population growth and demographic restructuring are driving the food and agriculture sectors to provide greater quantities and varieties of food, of which protein resources are particularly important. Traditional animal-source proteins are becoming increasingly difficult to meet the demand of the current consumer market, and the search for alternative protein sources is urgent. Microbial proteins are biomass obtained from nonpathogenic single-celled organisms, such as bacteria, fungi, and microalgae. They contain large amounts of proteins and essential amino acids as well as a variety of other nutritive substances, which are considered to be promising sustainable alternatives to traditional proteins. In this review, typical approaches to microbial protein synthesis processes were highlighted and the characteristics and applications of different types of microbial proteins were described. Bacteria, fungi, and microalgae can be individually or co-cultured to obtain protein-rich biomass using starch-based raw materials, organic wastes, and one-carbon compounds as fermentation substrates. Microbial proteins have been gradually used in practical applications as foods, nutritional supplements, flavor modifiers, and animal feeds. However, further development and application of microbial proteins require more advanced biotechnological support, screening of good strains, and safety considerations. This review contributes to accelerating the practical application of microbial proteins as a promising alternative protein resource and provides a sustainable solution to the food crisis facing the world.

Extracellular Purine Metabolism-Potential Target in Multiple Sclerosis

The purinergic signaling system comprises a complex network of extracellular purines and purine-metabolizing ectoenzymes, nucleotide and nucleoside receptors, ATP release channels, and nucleoside transporters. Because of its immunomodulatory function, this system is critically involved in the pathogenesis of multiple sclerosis (MS) and its best-characterized animal model, experimental autoimmune encephalomyelitis (EAE). MS is a chronic neuroinflammatory demyelinating and neurodegenerative disease with autoimmune etiology and great heterogeneity, mostly affecting young adults and leading to permanent disability. In MS/EAE, alterations were detected in almost all components of the purinergic signaling system in both peripheral immune cells and central nervous system (CNS) glial cells, which play an important role in the pathogenesis of the disease. A decrease in extracellular ATP levels and an increase in its downstream metabolites, particularly adenosine and inosine, were frequently observed at MS, indicating a shift in metabolism toward an anti-inflammatory environment. Accordingly, upregulation of the major ectonucleotidase tandem CD39/CD73 was detected in the blood cells and CNS of relapsing-remitting MS patients. Based on the postulated role of A2A receptors in the transition from acute to chronic neuroinflammation, the association of variants of the adenosine deaminase gene with the severity of MS, and the beneficial effects of inosine treatment in EAE, the adenosinergic system emerged as a promising target in neuroinflammation. More recently, several publications have identified ADP-dependent P2Y12 receptors and the major extracellular ADP producing enzyme nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) as novel potential targets in MS.

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

Poor serum uric acid control increases risk for developing hypertension: a retrospective cohort study in China

Background

Serum uric acid (SUA) has been suggested as a contributor of hypertension. However, reports on the relationship between changes in SUA and hypertension are limited. Hence, we aimed to investigate the potential impact of SUA, especially its change over time, on hypertension incidence.

Methods

This dynamic cohort included 6052 participants without hypertension at baseline. Participants were categorized into six grades based on whether baseline SUA was high and whether changes in SUA progressed to hyperuricemia or decreased to normal levels. Grades 1 to 6 represented the participants' SUA control from best to worst. Logistic regression and restricted cubic spline (RCS) models were used to explore the association of the grades of SUA control and hypertension incidence.

Results

During a median follow-up of 6 years, 2550 (42.1%) participants developed hypertension. After adjusting confounding factors, compared to grade 1 with the best control of SUA, the odds ratios for grades 2 to 6 with worse control were 1.347 (1.109-1.636), 1.138 (0.764-1.693), 1.552 (1.245-1.934), 1.765 (1.170-2.663), and 2.165 (1.566-2.993), respectively. RCS indicated a linear correlation between the risk of hypertension and changes in SUA, and an elevated risk in participants with baseline hyperuricemia. Subgroup analyses showed that grades of SUA control had an interaction with systolic (P = 0.003) and diastolic blood pressure (P < 0.001). Sensitivity analyses further determined the robustness of the result that participants with poor SUA control have a higher risk of developing hypertension.

Conclusion

Poor SUA control, an increase in SUA over time, rises the risk of developing hypertension regardless of whether the initial SUA is normal or not. Initial hyperuricemia will exacerbate this risk. Effective SUA control should be an important measure for primary prevention of hypertension.

Association between serum uric acid-to-high-density lipoprotein cholesterol ratio and insulin resistance in patients with type 2 diabetes mellitus

INTRODUCTION

Previous studies have shown that the serum uric acid-to-high-density lipoprotein cholesterol ratio (UHR) is related to metabolic syndrome. However, no existing study has examined the relationship between UHR and insulin resistance (IR). Therefore, this study aims to explore the association between the UHR and IR in patients with type 2 diabetes mellitus (T2DM).

METHODS

Patients with type 2 diabetes mellitus (1,532 males and 1,013 females) were enrolled. Insulin resistance was measured by homeostatic model assessment of insulin resistance (HOMA-IR) and was defined as HOMI-IR ≥ 2.69. Pearson correlation, multiple logistic regression, ROC analysis, and subgroup analysis were used to evaluate the association between UHR and IR.

RESULTS

UHR was associated with HOMA-IR in patients with type 2 diabetes mellitus (pearson's correlation coefficient = 0.274 in males and 0.337 in females, P < 0.001). Multiple logistic regression analysis showed that UHR was significantly correlated with insulin resistance (OR = 1.06, 95%CI = 1.03-1.08 in males and OR = 1.11, 95%CI = 1.08-1.15 in females). The area under the ROC curve (AUC) of UHR (AUC = 0.665 for males and 0.717 for females, all P < 0.01) was the largest compared with that of UA and HDL-C in insulin resistance. Subgroup analysis showed that there was a more significantly positive correlation among subjects with BMI ≥ 24 kg/m2 , age < 60 years old, HbA1c < 7%, non-hypertension, or in female subjects.

CONCLUSION

Elevated UHR is significantly correlated with insulin resistance, which can be used as an indicator of insulin resistance in patients with type 2 diabetes mellitus.

Coinfection with Schistosoma mansoni Enhances Disease Severity in Human African Trypanosomiasis

Introduction

Human African trypanosomiasis (HAT) and schistosomiasis are neglected parasitic diseases found in the African continent. This study was conducted to determine how primary infection with Schistosoma mansoni affects HAT disease progression with a secondary infection with Trypanosoma brucei rhodesiense (T.b.r) in a mouse model.

Methods

Female BALB-c mice (6-8 weeks old) were randomly divided into four groups of 12 mice each. The different groups were infected with Schistosoma mansoni (100 cercariae) and Trypanosoma brucei rhodesiense (5.0 × 104) separately or together. Twenty-one days after infection with T.b.r, mice were sacrificed and samples were collected for analysis.

Results

The primary infection with S. mansoni significantly enhanced successive infection by the T.b.r; consequently, promoting HAT disease severity and curtailing host survival time. T.b.r-induced impairment of the neurological integrity and breach of the blood-brain barrier were markedly pronounced on coinfection with S. mansoni. Coinfection with S. mansoni and T.b.r resulted in microcytic hypochromic anemia characterized by the suppression of RBCs, hematocrit, hemoglobin, and red cell indices. Moreover, coinfection of the mice with the two parasites resulted in leukocytosis which was accompanied by the elevation of basophils, neutrophils, lymphocytes, monocytes, and eosinophils. More importantly, coinfection resulted in a significant elevation of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin, creatinine, urea, and uric acid, which are the markers of liver and kidney damage. Meanwhile, S. mansoni-driven dyslipidemia was significantly enhanced by the coinfection of mice with T.b.r. Moreover, coinfection with S. mansoni and T.b.r led to a strong immune response characterized by a significant increase in serum TNF-α and IFN-γ. T.b.r infection enhanced S. mansoni-induced depletion of cellular-reduced glutathione (GSH) in the brain and liver tissues, indicative of lethal oxidative damage. Similarly, coinfection resulted in a significant rise in nitric oxide (NO) and malondialdehyde (MDA) levels.

Conclusion

Primary infection with S. mansoni exacerbates disease severity of secondary infection with T.b.r in a mouse model that is associated with harmful inflammatory response, oxidative stress, and organ injury.

The association between serum uric acid and hypertriglyceridemia: evidence from the national health and nutrition examination survey (2007-2018)

Background

Accumulating evidence suggests that elevated serum uric acid (SUA) may be a risk factor for hypertriglyceridemia (HTG). However, the epidemiological evidence for the association between SUA and HTG is limited. This article aimed to use the data from National Health and Nutrition Examination Survey (NHANES) (2007-2018) database to bridge the research gap.

Methods

This cross-sectional study used data from 10027 adults involved in NHANES from 2007-2018. We designed the exposure variable as SUA and the outcome variable as HTG. The covariates included demographics, questionnaires, laboratory, and examination information. Weighted logistic regression and subgroup analysis were used to explore the independent association between SUA and HTG. Furthermore, interaction tests were also carried out to evaluate the strata differences. Generalized additive models (GAM), smooth curve fittings, and threshold effect analysis were applied to examine the non-linear relationship.

Results

A total of 10027 participants were included, of which 3864 were HTG participants and 6163 were non-HTG participants. After fully adjusting for confounders, weighted multiple logistic regression models revealed a 77% increase in the risk of HTG when each unit of log2-SUA increased. There was also a positive association between elevated log2-SUA and developed risk of HTG in the quartile (Q) groups (Q1 OR: 1.00; Q2 OR: 1.17 [95%CI: 0.95,1.45]; Q3 OR: 1.43 [95%CI: 1.16,1.78]; Q4 OR: 1.68 [95%CI: 1.36,2.08]. The subgroup analysis results remained consistent across strata, with a strong positive correlation between SUA and HTG. Interaction tests showed no dependence on physical activity (PA), gender, BMI, smoking status, alcohol intake, hypertension, and diabetes for this positive association between log2-SUA and HTG (all p for interaction >0.05). The participants' age may impact the strength of the association between SUA and HTG (p for interaction <0.05).

Conclusion

There is a positive association between SUA and HTG in US adults. Considering that SUA may be a risk factor for HTG, individuals diagnosed with HTG should prioritize the daily management of SUA as part of their comprehensive care.

Resistin/uric acid index as a marker of metabolic syndrome in females with obesity

BACKGROUND

The resistin/uric index has been considered a prognostic factor for identifying young people with obesity. Obesity and Metabolic Syndrome (MS) are an important health problem in females.

AIMS

The objective of this work was to evaluate the relationship of resistin/acid uric index with Metabolic Syndrome on Caucasian females with obesity.

METHODS

We conducted a cross sectional study in 571 females with obesity. Measurements of anthropometric parameters, blood pressure, fasting blood glucose, insulin concentration, insulin resistance (HOMA-IR), lipid profile, C reactive protein, uric acid, resistin and prevalence of Metabolic Syndrome were determined. The resistin/uric acid index was calculated.

RESULTS

In total, 249 subjects had MS (43.6%). We detected higher levels in the following parameters (Delta; p values); waist circumference (3.1 ± 0.5 cm; p = 0.04), systolic blood pressure (5.3 ± 3.6 mmHg; p = 0.01), diastolic blood pressure (2.3 ± 0.4 mmHg; p = 0.02), glucose levels (7.5 ± 0.9 mg/dL; p = 0.01), insulin levels (2.5 ± 0.3 UI/L; p = 0.02), HOMA-IR (0.7 ± 0.2 units; p = 0.03), uric acid levels (0.9 ± 0.2 mg/dl; p = 0.01), resistin levels (4.1 ± 0.4 ng/dl; p = 0.01) and resistin/uric acid index (0.61 ± 0.01 mg/dl; p = 0.02) in subjects of the high resistin/uric acid index group than low index group. Logistic regression analysis reported a high percentage of hyperglycemia (OR = 1.77, 95% CI = 1.10-2.92; p = 0.02), hypertension (OR = 1.91, 95% CI = 1.36-3.01; p = 0.01), central obesity (OR = 1.48, 95% CI = 1.15-1.84; p = 0.03) and metabolic syndrome percentage (OR = 1.71, 95% CI = 1.22-2.69; p = 0.02) in high resistin/uric acid index group.

CONCLUSIONS

Resistin/uric acid index is related with Metabolic syndrome (MS) risk and criteria of it in a population of Caucasian females with obesity and this index is a correlated with glucose levels, insulin levels and insulin resistance (HOMA-IR).

Human Plasma Xanthine Oxidoreductase Activity in Cardiovascular Disease: Evidence from a Population-Based Study

Xanthine oxidoreductase (XOR) and its products contribute to the development of chronic inflammation and oxidative stress. Excessive XOR activity is believed to promote inflammatory responses and atherosclerotic plaque formation, which are major cardiovascular risk factors. The mechanisms of XOR activity in the development and progression of cardiovascular disease (CVD), coupled with the complexity of the relationship between XOR activity and the biological effects of uric acid; reactive oxygen species; and nitric oxide, which are the major products of XOR activity, have long been debated, but have not yet been clearly elucidated. Recently, a system for measuring highly sensitive XOR activity in human plasma was established, and there has been progress in the research on the mechanisms of XOR activity. In addition, there are accumulating findings about the relationship between XOR activity and CVD. In this narrative review, we summarize existing knowledge regarding plasma XOR activity and its relationship with CVD and discuss future perspectives.

The Good, the Bad and the New about Uric Acid in Cancer

Simple Summary

The concentration of uric acid in blood is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant and is a scavenger of singlet oxygen and radicals. At high intracellular concentration, uric acid has been demonstrated to act as a pro-oxidant molecule. Recently, uric acid has been reported to affect the properties of several proteins involved in metabolic regulation and signaling, and the relationship between uric acid and cancer has been extensively investigated. In this review, we present the most recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in the pathogenesis of several diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer.

Abstract

Uric acid is the final product of purine catabolism in man and apes. The serum concentration of uric acid is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant, while at high intracellular concentrations, it is a pro-oxidant molecule. In this review, we describe the possible causes of uric acid accumulation or depletion and some of the metabolic and regulatory pathways it may impact. Particular attention has been given to fructose, which, because of the complex correlation between carbohydrate and nucleotide metabolism, causes uric acid accumulation. We also present recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in a variety of signaling pathways, which can play a role in the pathogenesis of diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer. The loss of uricase in Homo sapiens and great apes, although exposing these species to the potentially adverse effects of uric acid, appears to be associated with evolutionary advantages.

Associations between body mass index in different childhood age periods and hyperuricemia in young adulthood: the China Health and Nutrition Survey cohort study

BACKGROUND

Few studies have evaluated the specific age period in childhood when the association of body mass index with adult hyperuricemia begins to be operative. This study aimed to examine the associations between body mass index in different childhood age periods and the risk of adult hyperuricemia in China.

METHODS

The study cohort from the China Health and Nutrition Survey included 676 participants who were aged ≥ 18 years and had data on uric acid in 2009 with at least one measurement of body mass index in childhood surveys before 2009. There were 357, 365, 358, 427, and 432 observations in childhood age groups of ≤ 5 years, 6-9 years, 10-12 years, 13-15 years, and 16-18 years, respectively. Body mass index Z score was calculated based on 2000 Center for Disease Control and Prevention growth charts for the United States.

RESULTS

Childhood body mass index Z scores measured at age ≤ 5 years, 6-9 years, 10-12 years, and 13-15 years had no statistical association with adult uric acid. In comparison, childhood body mass index Z scores measured at age 16-18 years were significantly associated with adult uric acid (β = 11.539, P = 0.007), and the strength of association was stronger in girls (β = 18.565, P = 0.002) than in boys (β = 9.209, P = 0.087). In addition, childhood body mass index Z scores measured at age 16-18 years were significantly associated with an increased risk of adult hyperuricemia (odds ratio = 1.323, 95% confidence interval = 1.003-1.746, P = 0.048), but not for other age groups.

CONCLUSION

The association between childhood body mass index and young adulthood hyperuricemia was influenced by childhood age.

Development of Laboratory Parameters-Based Formulas in Predicting Short Outcomes for Adult Hemophagocytic Lymphohistiocytosis Patients with Different Underlying Diseases

PURPOSE

Hemophagocytic lymphohistiocytosis (HLH) is a severe disease with high mortality. The purpose of this investigation was to build models to predict 30-day death in total and subgroup HLH patients based on available and cheap laboratory parameters.

METHOD

The research contained 431 adults HLH patients from January 2015 to September 2021 in the hospital. Logistic regression and receiver operating characteristic (ROC) were utilized to build models.

RESULTS

Results suggested that age, ferritin, lymphocyte (LY), international normalized ratio (INR), thrombin time (TT), globulin, uric acid (UA), chloride, activated partial thromboplastin time (APTT), aspartate aminotransferase (AST), triglycerides (TG), total bilirubin (TB), and indirect bilirubin (IB) were independent factors in HLH and subgroups. Then, models adapted to patients with different underlying diseases were established based on these factors. Area under curve (AUC) of these models was excellent: HLH patients: 0.838 (p < 0.001); infection-associated HLH (I-HLH) patients: 0.913 (p < 0.001); malignancy-associated HLH (M-HLH): 0.921 (p < 0.001) and 0.809 (p < 0.001) for two or more different etiologies-associated HLH (Mix-HLH patients). In addition, UA, TT, and chloride were firstly confirmed as independent factors in adult HLH.

CONCLUSION

Four models depending on biomarkers that available and affordable in clinical practice were built. With these models, high-risk patients with different underlying diseases could be easily identified.

Clinical Predictors and Long-term Impact of Acute Kidney Injury on Progression of Diabetic Kidney Disease in Chinese Patients With Type 2 Diabetes

We aim to assess the long-term impact of acute kidney injury (AKI) on progression of diabetic kidney disease (DKD) and all-cause mortality and investigate determinants of AKI in Chinese patients with type 2 diabetes (T2D). A consecutive cohort of 9,096 Chinese patients with T2D from the Hong Kong Diabetes Register was followed for 12 years (mean ± SD age 57 ± 13.2 years; 46.9% men; median duration of diabetes 5 years). AKI was defined based on the Kidney Disease: Improving Global Outcomes (KDIGO) criteria using serum creatinine. Estimated glomerular filtration rate measurements were used to identify the first episode with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Polygenic risk score (PRS) composed of 27 single nucleotide polymorphisms (SNPs) known to be associated with serum uric acid (SUA) in European populations was used to examine the role of SUA in pathogenesis of AKI, CKD, and ESRD. Validation was sought in an independent cohort including 6,007 patients (age 61.2 ± 10.9 years; 59.5% men; median duration of diabetes 10 years). Patients with AKI had a higher risk for developing incident CKD (hazard ratio 14.3 [95% CI 12.69-16.11]), for developing ESRD (12.1 [10.74-13.62]), and for all-cause death (7.99 [7.31-8.74]) compared with those without AKI. Incidence rate for ESRD among patients with no episodes of AKI and one, two, and three or more episodes of AKI was 7.1, 24.4, 32.4, and 37.3 per 1,000 person-years, respectively. Baseline SUA was a strong independent predictor for AKI. A PRS composed of 27 SUA-related SNPs was associated with AKI and CKD in both discovery and replication cohorts but not ESRD. Elevated SUA may increase the risk of DKD through increasing AKI. The identification of SUA as a modifiable risk factor and PRS as a nonmodifiable risk factor may facilitate the identification of individuals at high risk to prevent AKI and its long-term impact in T2D.

Mediating Effect of Body Mass Index and Dyslipidemia on the Relation of Uric Acid and Type 2 Diabetes: Results From China Health and Retirement Longitudinal Study

Objective

This study assessed temporal relationships of serum uric acid (SUA) with blood glucose and determine the mediating effects of body mass index (BMI) and dyslipidemia on the relation of SUA and risk of type 2 diabetes.

Methods

Participants aged ≥ 45 years were participated in 2011 and followed up until 2015. Cox proportional hazards regression with a robust variance estimator was performed to explore the association of SUA with the risk of diabetes, and crosslagged path analysis was introduced to examine the temporal relationships between SUA and blood glucose. A mediation analysis was finally used to identify the mediating effect of BMI and dyslipidemia on the relation of SUA and the future risk of diabetes.

Results

A total of 9,020 participants were included with an average age of 58.59 years at baseline in 2011, and 53.6% of them were women. Linear dose–response relationship was identified by restricted spline cubic analysis between baseline SUA and follow-up blood glucose (the non-linear trend for fasting plasma glucose (FPG): β2 = −0.71, p = 0.52; for HbA1c: β2 = 0.05, p = 0.07; for risk of diabetes: β2 = 0.12, p = 0.39). Additionally, compared with the lowest quartiles of SUA, the adjusted risk ratios of diabetes were 1.00 (95% CI: 0.82–1.23), 1.08 (95% CI: 0.89–1.31), and 1.37 (95% CI: 1.11–1.96) for quartile 2–4 (p-trend &lt; 0.01), respectively. Further additional adjustments for BMI or dyslipidemia, these ratios were not statistically significant. In addition, a unidirectional relationship from baseline SUA to follow-up FPG (ρ1 = 0.24, p = 0.03) was further confirmed using crosslagged path analysis. After stratifying by genders, the above results were only significant in the women subgroup, and we thus conducted a mediation analysis in women and found that the BMI and dyslipidemia partially mediated the effect of SUA on diabetes with a 23.05 and 18.82% mediating effect, respectively.

Conclusions

These findings provide strong evidence that hyperuricemia preceded diabetes, and the effect of baseline SUA on follow-up type 2 diabetes was more pronounced among middle-aged and elderly Chinese women, especially in postmenopausal women, and this effect is partly mediated by BMI and dyslipidemia at baseline.

Prevalence of asymptomatic hyperuricemia and its association with prediabetes, dyslipidemia and subclinical inflammation markers among young healthy adults in Qatar

AIM

The aim of this study is to investigate the prevalence of asymptomatic hyperuricemia in Qatar and to examine its association with changes in markers of dyslipidemia, prediabetes and subclinical inflammation.

METHODS

A cross-sectional study of young adult participants aged 18 - 40 years old devoid of comorbidities collected between 2012 and 2017. Exposure was defined as uric acid level, and outcomes were defined as levels of different blood markers. De-identified data were collected from Qatar Biobank. T-tests, correlation tests and multiple linear regression were all used to investigate the effects of hyperuricemia on blood markers. Statistical analyses were conducted using STATA 16.

RESULTS

The prevalence of asymptomatic hyperuricemia is 21.2% among young adults in Qatar. Differences between hyperuricemic and normouricemic groups were observed using multiple linear regression analysis and found to be statistically and clinically significant after adjusting for age, gender, BMI, smoking and exercise. Significant associations were found between uric acid level and HDL-c p = 0.019 (correlation coefficient -0.07 (95% CI [-0.14, -0.01]); c-peptide p = 0.018 (correlation coefficient 0.38 (95% CI [0.06, 0.69]) and monocyte to HDL ratio (MHR) p = 0.026 (correlation coefficient 0.47 (95% CI [0.06, 0.89]).

CONCLUSIONS

Asymptomatic hyperuricemia is prevalent among young adults and associated with markers of prediabetes, dyslipidemia, and subclinical inflammation.

Prevalence and associated factors of obesity and overweight in Chinese patients with bipolar disorder

OBJECT

Despite abundant literature demonstrating a high prevalence of obesity and overweight in people with bipolar disorder (BD), little is known about this topic in China. Therefore, we assessed the prevalence and associated factors of obesity and overweight among inpatients with BD in our hospital, one of the largest public psychiatric hospitals in China.

METHODS

In this retrospective, cross-sectional study, 1,169 inpatients ≥18 years with BD during 2019 were included. Obesity was defined as having a BMI ≥25 kg/m², and overweight was defined as having a BMI from 23 kg/m² to <25 kg/m². Binary logistic regression analysis was performed to identify factors associated with obesity and overweight.

RESULTS

The prevalence of obesity and overweight was 21.0% and 32.2% in patients with BD, respectively. Compared to patients with overweight and normal weight, patients with obesity were older, had a longer duration of BD and a longer length of hospital stay, had a higher prevalence of diabetes and hypertension, and had a higher level of all metabolic indices, except for HDL cholesterol. Binary logistic regression analysis showed that duration of BD, uric acid, alanine aminotransferase (ALT), triglyceride, and LDL cholesterol were significantly associated with obesity, and male sex and uric acid level were significantly associated with overweight (p < 0.05).

CONCLUSIONS

Obesity and overweight were fairly prevalent in Chinese BD patients, and several factors were related to obesity and overweight. The results of the present study call for the need to implement early screening, prevention and interventions for obesity and overweight in patients with BD in China.

A systematic review of metabolomic studies of childhood obesity: State of the evidence for metabolic determinants and consequences

Childhood obesity has become a global epidemic and carries significant long-term consequences to physical and mental health. Metabolomics, the global profiling of small molecules or metabolites, may reveal the mechanisms of development of childhood obesity and clarify links between obesity and metabolic disease. A systematic review of metabolomic studies of childhood obesity was conducted, following Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines, searching across Scopus, Ovid, Web of Science and PubMed databases for articles published from January 1, 2005 to July 8, 2020, retrieving 1271 different records and retaining 41 articles for qualitative synthesis. Study quality was assessed using a modified Newcastle-Ottawa Scale. Thirty-three studies were conducted on blood, six on urine, three on umbilical cord blood, and one on saliva. Thirty studies were primarily cross-sectional, five studies were primarily longitudinal, and seven studies examined effects of weight-loss following a life-style intervention. A consistent metabolic profile of childhood obesity was observed including amino acids (particularly branched chain and aromatic), carnitines, lipids, and steroids. Although the use of metabolomics in childhood obesity research is still developing, the identified metabolites have provided additional insight into the pathogenesis of many obesity-related diseases. Further longitudinal research is needed into the role of metabolic profiles and child obesity risk.

Association of the serum uric acid to creatinine ratio with metabolic syndrome in the middle age and older population in China

BACKGROUND

Metabolic syndrome (MetS) has attracted great interest, with an increasing prevalence. Recent studies have shown that the serum uric acid-to-creatinine ratio (SUACr) might be an excellent biomarker for MetS risk prediction in diabetic patients and postmenopausal women. However, the relationship between SUACr and MetS in a middle-aged and older population remains unclear.

METHODS

A total of 1277 participants were included in this cross-sectional study. Logistic regression modelling was performed to assess the association between SUACr and MetS in the total population. The dose-response relationship of SUACr and MetS was further assessed by a restricted cubic spline model (RCS). Furthermore, to explore the relationships between the levels of SUACr and the number of metabolic components, analysis of covariance (ANCOVA) was applied.

RESULTS

The levels of SUACr were lower in the non-MetS participants (OR 1.60, 95% CI 1.36 to 1.89; P<0.001),. Positive and dose-response relationships were further confirmed by the RCS model. We also found that, with increased number of components, the SUACr tended to increase. Moreover, values of SUACr were strongly related to levels of triglycerides (TGs), body mass index (BMI), blood glucose levels, systolic blood pressure/diastolic blood pressure (SBP/DBP), and hypertension. In addition, the positive association between SUACr and MetS also occurred in those patients with normal uric acid levels.

CONCLUSION

Elevated values of SUACr were strongly associated with an increased risk of MetS; this positive relationship remained in those individuals with normal uric acid levels.

Plasma Uric Acid Helps Predict Cognitive Impairment in Patients With Amyotrophic Lateral Sclerosis

Objective: Uric acid as an antioxidant plays an important role in neurodegenerative disease. Our objective is to investigate the relationship between plasma uric acid and cognitive impairment in patients with amyotrophic lateral sclerosis (ALS).

Methods: In this cross-sectional study, 124 ALS patients were screened by the Edinburgh Cognitive and Behavioral Screen (ECAS) and classified according to the revised Strong's criteria. Additionally, based on total ECAS cut-off score patients were categorized into those with cognitive impairment (ALS-cie) and those without cognitive impairment (ALS-ncie), and clinical data and uric acid level were compared between the two groups. Parameters with significant differences were further included in a multivariate linear regression analysis with ECAS score as a dependent variable. Hold-out validation was performed to evaluate the fitness of regression model.

Results: Up to 60% of ALS patients showed cognitive or/and behavioral impairment. The ALS-cie group had lower education level (p < 0.001), older age at symptom onset (p = 0.001), older age at testing (p = 0.001), and lower plasma uric acid (p = 0.01). Multivariate analysis showed increased uric acid (β = 0.214, p = 0.01), lower age at testing (β = −0.378, p < 0.001), and higher education level (β = 0.424, p < 0.001) could predict higher ECAS score (F = 19.104, R² = 0.381, p < 0.0001). Validation analysis showed that predicted ECAS score was significantly correlated with raw ECAS score in both the training set (rs = 0.621, p < 0.001) and the testing set (rs = 0.666, p < 0.001).

Conclusions: Cognitive impairment was a common feature in our Chinese ALS patients. Plasma uric acid might help evaluate the risk of cognitive impairment in ALS patients when combined with education level and age at testing.

Phylogenetic articulation of uric acid evolution in mammals and how it informs a therapeutic uricase

The role of uric acid during primate evolution has remained elusive ever since it was discovered over 100 years ago that humans have unusually high levels of the small molecule in our serum. It has been difficult to generate a neutral or adaptive explanation in part because the uricase enzyme evolved to become a pseudogene in apes thus masking typical signals of sequence evolution. Adding to the difficulty is a lack of clarity on the functional role of uric acid in apes. One popular hypothesis proposes that uric acid is a potent antioxidant that increased in concentration to compensate for the lack of vitamin C synthesis in primate species ∼65 million years ago (Mya). Here, we have expanded on our previous work with resurrected ancient uricase proteins to better resolve the reshaping of uricase enzymatic activity prior to ape evolution. Our results suggest that the pivotal death-knell to uricase activity occurred between 20-30 Mya despite small sequential modifications to its catalytic efficiency for the tens of millions of years since primates lost their ability to synthesize vitamin C, and thus the two appear uncorrelated. We also use this opportunity to demonstrate how molecular evolution can contribute to biomedicine by presenting ancient uricases to human immune cells that assay for innate reactivity against foreign antigens. A highly stable and highly catalytic ancient uricase is shown to elicit a lower immune response in more human haplotypes than other uricases currently in therapeutic development.

The study of routine laboratory factors in children with mycoplasma pneumoniae pneumonia: serum uric acid may have anti-inflammatory effect

Background

High uric acid levels are a risk factor for cardiovascular disorders, and metabolic diseases; however, the role of serum uric acid (sUA) during the mycoplasma pneumoniae pneumonia (MPP) of children is poorly known. This study aimed to clarify the effects of sUA during the MPP of children.

Methods

This was a prospective cohort study of children with MPP from multi‐center inpatient departments from September 2019 to August 2020. Routine laboratory characteristics analyzed including ALT, AST, BUN, CREA, UA, LDH, CK‐MB, WBC, N%, PLT, and CRP. Subjects were divided into 3 groups: non‐MPP, mild MPP (MMPP), and severe MPP (SMPP).

Results

949 subjects were enrolled, including 207 in non‐MPP, 565 in MMPP, and 177 in SMPP. The optimal cutoff value for sUA is 239 μmmol/L in receiver operating characteristic (ROC) curves analysis. Multivariate logistic regression showed that WBC and sUA had significance for protective effects between non‐MPP and SMPP, but CRP did not have significance between the two groups, N and PLT had significance for risk factors; WBC and sUA did not have significance for the protective effects between non‐MPP and MMPP, CRP had significance between the two groups, N and PLT had significance for the risk effects. Similarly, binary logistic regression showed UA, WBC, and CRP had significance for the protective effects between non‐MPP and MPP, but N and PLT had significance for the risk effects between the two groups.

Conclusion

Both multivariate and binary logistic regression demonstrated that sUA displayed a protective effect during the MPP of children, which meant sUA is anti‐inflammatory.

CRISPR-Cas9-mediated reactivation of the uricase pseudogene in human cells prevents acute hyperuricemia

The utility of CRISPR-Cas9 to repair or reverse diseased states that arise from recent genetic mutations in the human genome is now widely appreciated. The use of CRISPR to "design" the outcomes of biology is challenged by both specialized ethicists and the general public. Less of a focus, however, is the ability of CRISPR to provide metabolic supplements or prophylactic molecules that improve long-term human health by overwriting ancient evolutionary events. Here, we use CRISPR to genomically integrate a functional uricase gene that encodes an enzymatically active protein into the human genome. These uricase-producing cells are able to reduce or even eliminate high concentrations of exogenous uric acid despite the enzyme being localized to peroxisomes. Our evolutionary engineered cells represent the first instance of the primate ape lineage expressing a functional uricase encoded in the genome within the last 20 million years. We anticipate that human cells expressing uricase will help prevent hyperuricemia (including gout) as well as hypertension and will help protect against fatty liver disease in the future.

Fine-needle aspiration cytology finding uric acid crystals produced by Aspergillus

Uric acid is a metabolic product of nucleic acid and protein. Hyperuricemia results from failure or lack of urate oxidase. We present a case of a 61-year-old man with a painless forearm swelling, from which uric acid crystals were found on cytology. There were also septate fungal hyphae with morphology of Aspergillus, which has the source of the uric acid. Serum uric acid levels in our patient were normal.

Safety of Alternative Proteins: Technological, Environmental and Regulatory Aspects of Cultured Meat, Plant-Based Meat, Insect Protein and Single-Cell Protein

Food security and environmental issues have become global crises that need transformative solutions. As livestock production is becoming less sustainable, alternative sources of proteins are urgently required. These include cultured meat, plant-based meat, insect protein and single-cell protein. Here, we describe the food safety aspects of these novel protein sources, in terms of their technological backgrounds, environmental impacts and the necessary regulatory framework for future mass-scale production. Briefly, cultured meat grown in fetal bovine serum-based media can be exposed to viruses or infectious prion, in addition to other safety risks associated with the use of genetic engineering. Plant-based meat may contain allergens, anti-nutrients and thermally induced carcinogens. Microbiological risks and allergens are the primary concerns associated with insect protein. Single-cell protein sources are divided into microalgae, fungi and bacteria, all of which have specific food safety risks that include toxins, allergens and high ribonucleic acid (RNA) contents. The environmental impacts of these alternative proteins can mainly be attributed to the production of growth substrates or during cultivation. Legislations related to novel food or genetic modification are the relevant regulatory framework to ensure the safety of alternative proteins. Lastly, additional studies on the food safety aspects of alternative proteins are urgently needed for providing relevant food governing authorities with sufficient data to oversee that the technological progress in this area is balanced with robust safety standards.

Comparative lipid and uric acid suppressing properties of four common herbs in high fat-induced obese mice with their total phenolic and flavonoid index

Our present study was designed to investigate the comparative anti-obesity efficacy of ethanolic extract of Azadirachta indica A. Juss., Trigonella foenum-graecum L., Allium sativum L. and Zingiber officinale Roscoe in high fat-induced mice with their total phenolic and flavonoid profile. Total phenolic and flavonoid content were determined by Folin–Ciocalteu's and Aluminium chloride UV method respectively. In our study, 55 healthy mice were separated into 11 groups to take their respective treatments. Lipid and uric acid profile were estimated by using the enzymatic colourimetric method. Ethanolic extract of A. indica contained the highest phenolic and flavonoid content. A. indica normal and high fat diet group showed reduced weight gaining tendency than other extract groups. A. indica at a dose of 400 mg/kg body weight significantly (p < 0.001) reduced serum cholesterol (SC), triglyceride (TG), and uric acid (UA) level than other three extracts when compared with the control group. Thus, a considerable correlation was found between serum uric acid reducing potentials of the present experimental extracts with a lipid-lowering profile. Pathological examination revealed that the average weight of liver and kidney were significantly decreased in A. indica normal. Results obtained from the present study it can be concluded that ethanolic extract of A. indica possesses better lipid-lowering efficacy than the other three herbs.

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Ethanolic extract of A. indica contained the highest phenolic and flavonoid content.

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A. indica significant reduced the serum TC, TG, and UA level than other three extracts when compared with the control group.

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The average weight of liver and kidney were significantly decreased in A. indica.

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A. indica possesses better lipid-lowering efficacy than the other three herbs.

Uric acid lowering improves insulin sensitivity and lowers blood pressure: a meta-analysis of randomized parallel-controlled clinical trials

Objectives

This meta-analysis aimed to investigate whether uric acid lowering treatment can improve β-cell function and insulin sensitivity.

Methods

PubMed, Cochrane Library, EMBASE and China Biology Medicine were searched up to March 1, 2020. Randomized controlled clinical trials of urate lowering therapy in hyperuricemia patients were included in meta-analysis. Effect size was estimated as mean difference with 95% confidence interval (CI).

Results

Our search yielded 7 eligible trials with 503 participants. This meta-analysis showed that uric acid-lowering therapy decreased fasting insulin -1.43 µIU/ml (weighted mean differences (WMD, 95% CI -2.78 to -0.09), homeostasis model assessment of insulin resistance -0.65 (WMD, 95% CI -1.05 to -0.24), systolic blood pressure -2.45 mm Hg (WMD, 95%CI -4.57 to -0.33) and diastolic blood pressure -3.41 mm Hg (WMD, 95%CI -3.87 to -2.95). However, the treatment had no significant effect on fasting plasma glucose (WMD -0.19 mmol/L, 95%CI -0.42 to 0.05), homeostasis model assessment of β-cell function index (WMD -0.02, 95%CI -0.28 to 0.24), total cholesterol (WMD 0.18 mg/dl; 95%CI, -1.39 to 1.75) and triglyceride (WMD 3.15 mg/dl, 95% CI -9.83 to 16.14).

Conclusion

Uric acid-lowering therapies might improve insulin sensitivity and lower blood pressure, but had no significant effect on HOMA-β and serum lipids.

Association between serum uric acid and obesity in Chinese adults: a 9-year longitudinal data analysis

OBJECTIVES

Hyperuricaemia has been reported to be significantly associated with risk of obesity. However, previous studies on the association between serum uric acid (SUA) and body mass index (BMI) yielded conflicting results. The present study examined the relationship between SUA and obesity among Chinese adults.

METHODS

Data were collected at Guangdong Second Provincial General Hospital in Guangzhou City, China, between January 2010 and December 2018. Participants with ≥2 medical check-up times were included in our analyses. Physical examinations and laboratory measurement variables were obtained from the medical check-up system. The high SUA level group was classified as participants with hyperuricaemia, and obesity was defined as BMI ≥28 kg/m². Logistic regression model was performed for data at baseline. For all participants, generalised estimation equation (GEE) model was used to assess the association between SUA and obesity, where the data were repeatedly measured over the 9-year study period. Subgroup analyses were performed by gender and age group. We calculated the cut-off values for SUA of obesity using the receiver operating characteristic curves (ROC) technique.

RESULTS

A total of 15 959 participants (10 023 men and 5936 women) were included in this study, with an average age of 37.38 years (SD: 13.27) and average SUA of 367.05 μmol/L (SD: 97.97) at baseline, respectively. Finally, 1078 participants developed obesity over the 9-year period. The prevalence of obesity was approximately 14.2% for high SUA level. In logistic regression analysis at baseline, we observed a positive association between SUA and risk of obesity: OR=1.84 (95% CI: 1.77 to 1.90) for per-SD increase in SUA. Considering repeated measures over 9 year for all participants in the GEE model, the per-SD OR was 1.85 (95% CI: 1.77 to 1.91) for SUA and the increased risk of obesity were greater for men (OR=1.45) and elderly participants (OR=1.01). In subgroup analyses by gender and age, we observed significant associations between SUA and obesity with higher risk in women (OR=2.35) and young participants (OR=1.87) when compared with men (OR=1.70) and elderly participants (OR=1.48). The SUA cut-off points for risk of obesity using ROC curves were approximately consistent with the international standard.

CONCLUSIONS

Our study observed higher SUA level was associated with increased risk of obesity. More high-quality research is needed to further support these findings.

Xanthine oxidoreductase: One enzyme for multiple physiological tasks

Human xanthine oxidoreductase (XOR) is a multiple-level regulated enzyme, resulting from a complicated evolutionary process that assigned it many physiological roles. The main XOR activities are: (i) xanthine dehydrogenase (XDH) activity that performs the last two steps of purine catabolism, from hypoxanthine to uric acid; (ii) xanthine oxidase (XO) activity that, besides purine catabolism, produces reactive oxygen species (ROS); (iii) nitrite reductase activity that generates nitric oxide, contributing to vasodilation and regulation of blood pressure; (iv) NADH oxidase activity that produces ROS. All these XOR activities contribute also to metabolize various endogenous and exogenous compounds, including some drugs. About XOR products, it should be considered that (i) uric acid is not only a proinflammatory agent, but also a fundamental antioxidant molecule in serum and (ii) XOR-derived ROS are essential to the inflammatory defensive response. Although XOR has been the object of a large number of studies, most of them were focused on the pathological consequences of its activity and there is not a clear and schematic picture of XOR physiological roles. In this review, we try to fill this gap, reporting and graphically schematizing the main roles of XOR and its products.

Renal lipid accumulation, oxidative stress and uric acid handling in a rodent model of obesity and metabolic syndrome

Hyperuricemia is more prevalent among people with obesity and metabolic syndrome, and is associated with adverse clinical outcomes. We hypothesized that increased renal reabsorption of uric acid (UA) in obesity and metabolic syndrome may be an adaptive response of the kidney when faced with fatty acid-induced oxidative stress. To test this hypothesis, we examined lipid accumulation, markers of oxidative stress, and renal UA handling in Zucker diabetic fatty (ZDF) rats, and in matched lean control animals. Rats were randomized to either normal rodent chow or a diet supplemented with antioxidants (α-tocopheryl acetate, sodium selenite, zinc sulfate, and ascorbic acid), and were followed up for either 4 or 20 weeks after randomization. Dietary antioxidant supplementation had no significant effects in lean control rats but led to partial improvement in markers of elevated oxidative stress in the kidney of ZDF rats. Renal UA handling was not affected by antioxidant supplementation. We observed robust correlations between renal lipid content and oxidative stress markers in the pooled experimental groups, particularly in older animals after 20 weeks on the study diets. Dietary antioxidant supplementation did not prevent the gradual decline in renal function observed in older ZDF rats. These findings suggest that hyperuricemia in the ZDF rat model of obesity and the metabolic syndrome is not caused by renal oxidative stress, that there may be a pathophysiological link between lipid accumulation and oxidative stress in the kidney, and that antioxidant supplementation does not prevent age-related decline in renal function in ZDF rats.

The Role of Soluble Uric Acid in Modulating Autophagy Flux and Inflammasome Activation during Bacterial Infection in Macrophages

Autophagy is a homeostatic process that regulates and recycles intracellular structures and is a host defense mechanism that facilitates bacterial clearance. Uric acid in plasma is a major antioxidant but in certain conditions acts as an inflammatory danger signal. The aim of this study is to investigate the effect of soluble uric acid on autophagy and the inflammatory responses in macrophages during bacterial infection. Herein, we employed murine RAW264.7 macrophages that express uricase enzyme and human THP-1 cells that are uricase-deficient. Three different strains of Staphylococcus aureus and two different strains of Klebsiella pneumoniae were used to infect macrophages in presence and absence of soluble uric acid. We found that soluble uric acid enhanced autophagy flux in infected macrophages. We observed that IL-1β increased during bacterial infection but decreased when macrophages were co-stimulated with bacteria and uric acid. In contrast to IL-1β, soluble uric acid did not affect TNFα release and there were no dramatic differences when macrophages were infected with S. aureus or K. pneumoniae. In conclusion, uric acid enhances autophagy flux during bacterial infection, consequently reducing inflammasome activation in macrophages. Understanding the effect of uric acid on the interplay between autophagy and inflammation will facilitate therapeutic design.

Uric Acid and Urate in Urolithiasis: The Innocent Bystander, Instigator, and Perpetrator

Uric acid is an end product of purine metabolism in human beings. An unusual and still unexplained phenomenon is that higher primates have relatively high uric acid levels in body fluids owing to a combination of absence of degradation and renal retention. The physiologic purpose of high uric acid levels still is enigmatic, but the pathobiologic burden is a variety of crystallopathies owing to the low aqueous solubility of uric acid such as gouty arthritis and acute uric acid nephropathy. In the urinary space, three distinct conditions result from chronic uric acid and/or urate precipitation. The first and most common variety is uric acid urolithiasis. In this condition, urate is a victim of a systemic metabolic disease in which increased acid load to the kidney is coupled with diminished urinary buffer capacity owing to defective ammonium excretion, resulting in titration of urate to its sparingly soluble protonated counterpart, uric acid, and the formation of stones. Uric acid is the innocent bystander of the crime. The second variety is hyperuricosuric calcium urolithiasis, in which uric acid confers lithogenicity via promotion of calcium oxalate precipitation by multiple mechanisms involving soluble, colloidal, and crystalline urate salts. Uric acid is the instigator of the crime. The third and least common condition involves urate as an integral part of the urolith as an ammonium salt driven by high ammonium and high urate concentrations in urine. Here, uric acid is one of the perpetrators of the crime. Both known and postulated pathogenesis of these three types of urolithiasis are reviewed and summarized.

New insights into purine metabolism in metabolic diseases: role of xanthine oxidoreductase activity

Xanthine oxidoreductase (XOR) consists of two different forms, xanthine dehydrogenase and xanthine oxidase (XO), and is a rate-limiting enzyme of uric acid production from hypoxanthine and xanthine. Uric acid is the end product of purine metabolism in humans and has a powerful antioxidant effect. The lack of ascorbic acid, known as vitamin C, in hominoids has been thought to cause a compensatory increase in uric acid as an antioxidant by unfunctional gene mutation of uricase to a pseudogene. Because XO is involved in an increase in reactive oxygen species (ROS) by generating superoxide and hydrogen peroxide, inadequate activation of XOR promotes oxidative stress-related tissue injury. Plasma XOR activity is associated with obesity, smoking, liver dysfunction, hyperuricemia, dyslipidemia, insulin resistance, and adipokines, indicating a novel biomarker of metabolic disorders. However, XOR activity in adipose tissue is low in humans unlike in rodents, and hypoxanthine is secreted from human adipose tissue. The concentration of hypoxanthine, but not xanthine, is independently associated with obesity in a general population, indicating differential regulation of hypoxanthine and xanthine. Treatment with an XOR inhibitor can decrease uric acid for preventing gout, reduce production of XO-related ROS, and promote reutilization of hypoxanthine and ATP production through the salvage pathway. It has recently been suggested that discontinuation of an XOR inhibitor causes adverse cardiovascular outcomes as XOR inhibitor withdrawal syndrome, possibly due to cardiac disturbance of conduction and contraction by reduced ATP production. New insights into purine metabolism, including the role of XOR activity in the past 5 yr, are mainly discussed in this review.

Assessment of the toxicity and biochemical effects of detergent processed cassava on renal function of Wistar rats

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The acute toxicity showed increase mortality with increased detergent concentration.

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Plasma and urine creatinine and urea was found to be high in the treated rats.

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Renal photomicrographs showed distorted pattern of corpuscles and tubules.

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The practice of adding detergent to cassava should be discontinued.

Fufu is a major component of food in West Africa. Local cassava farmers use detergent to ferment cassava root tuber during processing into fufu. Studies have established the hazardous health effects of detergent in humans. This study was carried out to determine the median lethal toxicity of detergent-processed cassava, and assessed its effects on the renal function of male Wistar rats. Fufu with different concentrations of detergent (250, 500 and 750 g/l) were given as food twice daily to the rats for the acute toxicity study. The sub-chronic test lasted for four weeks, during which the fufu samples prepared with 10, 20, 30, 40 and 50 g/l of detergent, were separately given to five groups of five rats, respectively. The results of the acute toxicity test showed increase in mortality with corresponding increase in detergent concentration. Plasma and urine creatinine and urea concentrations of all the detergent-treated rats were significantly higher than that of the negative and positive controls. Urinalysis showed significant presence of glucose and ketone bodies, as well as, blood and protein. Renal photomicrographs showed deranged cortical structure with diffuse loss of tubules, inflammatory cells infiltrate in the interstitium. The study concluded that detergent-processed cassava has adverse effects on the structure and function of the kidneys of rats.

U-shaped relationship between serum uric acid level and decline in renal function during a 10-year period in female subjects: BOREAS-CKD2

While hyperuricemia is recognized as a risk factor for chronic kidney disease (CKD), the risk of CKD in subjects with a low level of serum uric acid (UA) remains controversial. Here, we examined whether the association of CKD risk with serum UA level differs depending on the sex and age of subjects in a general population. Of subjects who received annual health checkups, we enrolled 6,779 subjects (male/female: 4,454/2,325; age: 45 ± 9 years) with data from a 10-year follow-up after excluding subjects taking anti-hyperuricemic drugs and those with CKD at baseline. During the follow-up period, 11.4% of the males and 11.7% of the females developed CKD. A significant interaction of sex, but not age, with the effect of baseline UA level on CKD risk was found. A restricted cubic spline analysis showed a U-shaped association of the baseline UA level with the risk of CKD in females. Multivariable Cox proportional hazard analyses for females showed that baseline UA levels in the 5th quintile (Q5, ≥5 mg/dL; HR: 1.68) and the 1st quintile (Q1, ≤3.5 mg/dL; HR: 1.73) were independent risk factors for CKD when compared with UA levels in the 4th quintile (Q4, 4.5-4.9 mg/dL). In males, restricted cubic spline analysis indicated increased CKD risk in subjects with a higher baseline UA level but not in those with a low UA level. In conclusion, a low UA level is a significant risk factor for CKD in females, while an elevated UA level increases the risk of CKD in both sexes.

Soluble uric acid induces myocardial damage through activating the NLRP3 inflammasome

Uric acid crystal is known to activate the NLRP3 inflammasome and to cause tissue damages, which can result in many diseases, such as gout, chronic renal injury and myocardial damage. Meanwhile, soluble uric acid (sUA), before forming crystals, is also related to these diseases. This study was carried out to investigate whether sUA could also activate NLRP3 inflammasome in cardiomyocytes and to analyse the mechanisms. The cardiomyocyte activity was monitored, along with the levels of mature IL‐1β and caspase‐1 from H9c2 cells following sUA stimulus. We found that sUA was able to activate NLRP3 inflammasome, which was responsible for H9c2 cell apoptosis induced by sUA. By elevating TLR6 levels and then activating NF‐κB/p65 signal pathway, sUA promoted NLRP3, pro‐caspase 1 and pro‐IL‐1β production and provided the first signal of NLRP3 inflammasome activation. Meanwhile, ROS production regulated by UCP2 levels also contributed to NLRP3 inflammasome assembly and subsequent caspase 1 activation and mature IL‐1β secretion. In addition, the tlr6 knockdown rats suffering from hyperuricemia showed the lower level of IL‐1β and an ameliorative cardiac function. These findings suggest that sUA activates NLRP3 inflammasome in cardiomyocytes and they may provide one therapeutic strategy for myocardial damage induced by sUA.

The ABCG2 Q141K hyperuricemia and gout associated variant illuminates the physiology of human urate excretion

The pathophysiological nature of the common ABCG2 gout and hyperuricemia associated variant Q141K (rs2231142) remains undefined. Here, we use a human interventional cohort study (ACTRN12615001302549) to understand the physiological role of ABCG2 and find that participants with the Q141K ABCG2 variant display elevated serum urate, unaltered FEUA, and significant evidence of reduced extra-renal urate excretion. We explore mechanisms by generating a mouse model of the orthologous Q140K Abcg2 variant and find male mice have significant hyperuricemia and metabolic alterations, but only subtle alterations of renal urate excretion and ABCG2 abundance. By contrast, these mice display a severe defect in ABCG2 abundance and function in the intestinal tract. These results suggest a tissue specific pathobiology of the Q141K variant, support an important role for ABCG2 in urate excretion in both the human kidney and intestinal tract, and provide insight into the importance of intestinal urate excretion for serum urate homeostasis.

The common ABCG2 variant Q141K contributes to hyperuricemia and gout risk. Here, using a human interventional study and a new orthologous mouse model, the authors report a tissue specific pathobiology of the Q141K variant, and support a significant role for ABCG2 in urate excretion in both the kidney and intestine.

Association of serum uric acid concentration with components of pediatric metabolic syndrome: A systematic review and meta-analysis

Background:

Hyperuricemia is implicated in the pathogenesis of inflammatory diseases and metabolic disorders. Metabolic syndrome (MetS) in childhood is one of the most important causes of different noncommunicable diseases in adulthood. This study aimed to systematically review the association between serum uric acid (UA) concentration and components of pediatric MetS.

Materials and Methods:

In this meta-analysis and systematic review, related articles were gathered by searching English databases including PubMed, Web of Science, Scopus, and Google Scholar. We used the following keywords: uric acid, metabolic syndrome, hypertension, fasting blood sugar (FBS), hyperglycemia; the search was limited to English language and included observational and cohort studies performed among children or adolescents. Pooled relative risks (odds ratio [OR]) and corresponding 95% confidence interval (95% CI) were extracted. A random-effect model was used.

Results:

On the basis of 34 eligible studies, the pooled correlation between UA with metabolic components including FBS (r = 0.24, 95% CI = 0.09–0.40), fasting insulin (r = 0.26, 95% CI = 0.15–0.37), and hyperglycemia (r for triglyceride and UA = 0.23, 95% CI = 0.19–0.38) (r for high-density lipoprotein and UA = −0.28, 95% CI = −0.37 to −0.20) was statistically significant. The association of both diastolic blood pressure (DBP) and systolic blood pressure (SBP) was statistically significant with UA (r for SBP and UA = 0.34, 95% CI = 0.24–0.43; r for DBP and UA = 0.18, 95% CI = 0.11–0.25). The OR between risk of abdominal obesity with UA was statistically significant (OR = 2.62, 95% CI = 1.41–3.84).

Conclusion:

Serum UA concentration is associated with major components of the pediatric MetS. Its measurement and control should be underscored in at-risk children and adolescents.

Resistin/Uric Acid Index as a Prognostic Factor in Adolescents with Obesity after Lifestyle Intervention

OBJECTIVE

To evaluate the resistin/uric acid index as a prognostic factor associated with body mass index (BMI) z-score change after 1 year of lifestyle interventions for obesity.

STUDY DESIGN

In this prospective cohort study, we included 102 adolescents with overweight or obesity (BMI ≥85th percentile). Weight and height were measured at the start of the lifestyle change intervention and 12 months later. Serum levels of resistin and uric acid were quantified at the beginning of the intervention. The intervention consisted of nutrition education, exercise, and physical activity promotion.

RESULTS

The sample included 54 girls and 48 boys; the median age was 11 years (range 10-16 years). The BMI z-score decreased during follow-up (median BMI z-score at baseline was 1.81 vs 1.70 after 1 year, P < .001). The resistin/uric acid index was positively correlated with BMI z-score change (r = 0.27, P < .01). In the linear regression analysis, the resistin/uric acid index was significantly associated with BMI z-score modification at the 12-month follow-up (β = 0.17; 95% CI 0.08-0.26; P < .01).

CONCLUSIONS

The resistin/uric acid index can be considered a prognostic factor for identifying adolescents with overweight or obesity with a greater probability of improving their BMI. This index could help establish different interventions for adolescents with overweight and obesity; however, additional studies are needed to confirm the usefulness of this index.

Investigating MIF in Mouse Model of Gout

Mice are widely used to assess the pathogenesis of diseases. An experimental model of gout consists of the injection of uric acid crystals into joints of mice, which reproduce inflammation and functional changes of the human disease. Uric acid crystals activate synoviocytes culminating in the release of IL-1β and neutrophil recruitment, key inflammatory elements in gouty arthritis. Since MIF plays an important role in orchestrating gout inflammation, we detail valuable procedures to investigate uric acid crystal-induced joint inflammation in mice and give options for further understanding the functions of MIF in gouty arthritis in vivo and in vitro.

Associations Between Serum Uric Acid Concentrations and Cardiometabolic Risk and Renal Injury in Obese and Overweight Children

OBJECTIVE

The aim of this study was to assess the association between serum uric acid concentration (SUAC) and the parameters of the metabolic syndrome (MetS) and insulin resistance (IR). The secondary aim was to evaluate whether hyperuricemia is associated with renal injury and cardiovascular risk in obese (OB) and overweight (OW) children.

METHODS

The subjects of this study consisted of OB/OW children and adolescents (ages: 8-18 years). Sex and age specific serum uric acid (SUA) olarak değiştirilecek percentiles were used and a SUA >75^th percentile was accepted as hyperuricemia. Anthropometric data, blood pressure (BP) measurements and biochemical parameters, including fasting blood glucose, insulin, total cholesterol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol, triglycerides (TG), aspartate aminotransferase, alanine aminotransferase, homeostatic model assessments of IR (HOMA-IR) and SUAC were recorded. Oral glucose tolerance tests (OGTT) were performed in all patients. MetS was defined according to the International Diabetes Federation criteria. Total cholesterol/HDL-c ratio >4 and TG/HDL-c ratio >2.2 were used as the atherogenic index (AI) indicating cardiovascular risk. Urinary albumin excretion in a 24-hour and also in a first-morning urine sample were measured. Renal injury was assessed by microalbuminuria according to the National Kidney Foundation criteria.

RESULTS

There were 128 participants; 52 (40%) had elevated (SUA >75^th percentile) and 76 had (60%) normal SUAC. The mean±SD age was 13.1±2.6 years and 87 (67.4%) were female. The mean±SD weight was 73±18.97 kg and mean±SD height was 155.4±12.11 cm. There was no statistical difference between the groups with and without hyperuricemia in terms of age, sex, puberty stage and degree of obesity. Increased SUAC were significantly associated with higher waist-to-hip ratio (WHR), fasting insulin levels and insulin at 30 and 60 minutes during OGTT, HOMA-IR, lower HDL-c and presence of hypertriglyceridemia as well as with decreased HDL-c, increased AI, presence of IR and MetS. BP and microalbuminuria were not associated with SUAC. SUAC showed significant positive correlations with waist circumference, WHR, post-challenge glucose level at 60 minutes, with fasting insulin, post-challenge insulin levels at 30, 60, 90 and 120 minutes and also with HOMA-IR, total cholesterol/HDL-c ratio, TG/HDL-c ratio and a number of other criteria related to MetS. Also, an inverse correlation with HDL-c was noted.

CONCLUSION

In OB/OW children frequency of MetS, IR and dislipidemia increases with increased SUAC, a finding independent of age, puberty, gender and body mass index. Patients meeting all of the MetS criteria had the highest SUAC. These results demonstrate that the association between UA and metabolic and cardiovascular risk factors can be detected early in childhood. Thus, we recommend monitoring SUAC in OB children and we believe that prevention of SUAC elevation in early life has a potential protective effect on metabolic impairment and subsequent comorbidities.

Impact of Early Life or Intrauterine Factors and Socio-Economic Interaction on Diabetes - An Evidence on Thrifty Hypothesis

Diabetes mellitus is one of the most concerning non-communicable diseases worldwide. The prevalence of diabetes increased rapidly by the influence of socioeconomic interactions. The thrifty hypothesis postulates that certain genes that are involved in positive selection promote efficient fat deposition and storage. This is beneficial for the survival of mankind in adverse conditions. However, in this modern society, these genes have become disadvantageous as people are significantly less likely to experience famines and nutrition shortages. The socioeconomic development that has occurred during the 20th century induced abundance of food supplies in almost all regions of the world. This has led to a rapid rise in the prevalence of obesity, and type 2 diabetes as a consequence. Boom of diabetic pandemic in newly developed countries compare with others those who developed gradually can be explain by thrifty hypothesis, as a result of the difference in the exposure to environmental factors and famine by the ancestors leads. The globalization, urbanization, lack of physical activity, intake of high calorie food and migration is major cause of pandemic emergence of diabetes in high as well as middle and low-income countries.

Association of the ESR1 polymorphism with menopause and MLXIPL genetic variant influence serum uric acid levels in Slovak midlife women

OBJECTIVE

This study examines associations between the ESR1 (XbaI, PvuII) and the MLXIPL (rs3812316) gene polymorphisms, and uric acid (UA) levels in Slovak midlife women, subdivided according to their menopause status.

METHODS

We assessed a total of 362 women from 38 to 65 years of age. Women were recruited from different localities in the western and middle parts of Slovakia. Participants were interviewed during their medical examination at local health centers. They were investigated with respect to a variety of aspects such as medical, anthropometrical, and lifestyle. Participants provided a blood sample for biochemical analyses and DNA genotyping. The MLXIPL gene (rs3812316 SNP variant) and ESR1 gene (PvuII and XbaI) genotypes were then detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Data were analyzed using general linear models and multiple linear regression analyses to adjust for risk factors elevating the UA level such as fat mass (FM), triglycerides (TGs) and creatinine.

RESULTS

A positive association between MLXIPL and UA level was observed in the total sample of women after control for confounding covariates, including FM, TGs, and creatinine (P = 0.027). Women with the CC genotype had higher UA levels than the G-allele carriers (261.5 μmol/L ± 68.3 vs 241.1 μmol/L ± 55.1 P = 0.013). A statistically significant association was noticed between postmenopause status and the ESR1 XbaI genotype and their effect on UA (P = 0.028). The Bonferroni pairwise comparison determined that the G-allele carriers in the postmenopausal period had higher estimated UA marginal mean (269.7 μmol/L) than the AA-allele postmenopausal women (236.5 μmol/L) (P = 0.012). The estimated UA marginal mean showed a significant increasing trend according to the MS in G allele carriers (248.5 μmol/L in pre/peri-menopausal vs 269.7 μmol/L in postmenopausal, P = 0.009). In contrast, a decreasing trend was observed in AA carriers (250.6 μmol/L in pre/perimenopausal women vs 236.5 μmol/L in postmenopausal). However, this trend was not statistically significant (P = 0.288).

CONCLUSIONS

This cross-sectional study suggests that MLXIPL (rs3812316) polymorphism is associated with higher serum UA levels and that the ESR1 (XbaI) polymorphism is associated with UA levels only in the postmenopausal cohort.

Are we close to defining a metabolomic signature of human obesity? A systematic review of metabolomics studies

INTRODUCTION

Obesity is a disorder characterized by a disproportionate increase in body weight in relation to height, mainly due to the accumulation of fat, and is considered a pandemic of the present century by many international health institutions. It is associated with several non-communicable chronic diseases, namely, metabolic syndrome, type 2 diabetes mellitus (T2DM), cardiovascular diseases (CVD), and cancer. Metabolomics is a useful tool to evaluate changes in metabolites due to being overweight and obesity at the body fluid and cellular levels and to ascertain metabolic changes in metabolically unhealthy overweight and obese individuals (MUHO) compared to metabolically healthy individuals (MHO).

OBJECTIVES

We aimed to conduct a systematic review (SR) of human studies focused on identifying metabolomic signatures in obese individuals and obesity-related metabolic alterations, such as inflammation or oxidative stress.

METHODS

We reviewed the literature to identify studies investigating the metabolomics profile of human obesity and that were published up to May 7th, 2019 in SCOPUS and PubMed through an SR. The quality of reporting was evaluated using an adapted of QUADOMICS.

RESULTS

Thirty-three articles were included and classified according to four types of approaches. (i) studying the metabolic signature of obesity, (ii) studying the differential responses of obese and non-obese subjects to dietary challenges (iii) studies that used metabolomics to predict weight loss and aimed to assess the effects of weight loss interventions on the metabolomics profiles of overweight or obese human subjects (iv) articles that studied the effects of specific dietary patterns or dietary compounds on obesity-related metabolic alterations in humans.

CONCLUSION

The present SR provides state-of-the-art information about the use of metabolomics as an approach to understanding the dynamics of metabolic processes involved in human obesity and emphasizes metabolic signatures related to obesity phenotypes.

The validity, stability, and utility of measuring uric acid in saliva

AIM

Serum uric acid (UA) is associated with many health conditions, including kidney, cardiovascular, and metabolic disorders. We examined the validity and stability of salivary UA as a noninvasive measure of serum UA.

MATERIALS & METHODS

Using serum and salivary UA data from healthy adults (n = 99), we examined the UA serum-saliva correlation, and UA associations with adiponectin and C-reactive protein. Using longitudinal data from young adults (n = 182), we examined salivary UA stability.

RESULTS

We found robust positive serum-saliva correlations for UA. UA and adiponectin were inversely related in serum and saliva. Salivary UA was relatively stable; 62-66% of variance could be attributed to a latent trait-like component.

CONCLUSION

Salivary UA may be an important biomarker indexing health and disease risk.

The role of xanthine oxidoreductase and uric acid in metabolic syndrome

Xanthine oxidoreductase (XOR) could contribute to the pathogenesis of metabolic syndrome through the oxidative stress and the inflammatory response induced by XOR-derived reactive oxygen species and uric acid. Hyperuricemia is strongly linked to hypertension, insulin resistance, obesity and hypertriglyceridemia. The serum level of XOR is correlated to triglyceride/high density lipoprotein cholesterol ratio, fasting glycemia, fasting insulinemia and insulin resistance index. Increased activity of endothelium-linked XOR may promote hypertension. In addition, XOR is implicated in pre-adipocyte differentiation and adipogenesis. XOR and uric acid play a role in cell transformation and proliferation as well as in the progression and metastatic process. Collected evidences confirm the contribution of XOR and uric acid in metabolic syndrome. However, in some circumstances XOR and uric acid may have anti-oxidant protective outcomes. The dual-face role of both XOR and uric acid explains the contradictory results obtained with XOR inhibitors and suggests caution in their therapeutic use.

Temporal relationship between hyperuricemia and obesity, and its association with future risk of type 2 diabetes

BACKGROUND/OBJECTIVES

Although hyperuricemia and obesity are significantly correlated, their temporal relationship and whether this relationship is associated with future risk of diabetes are largely unknown. This study examined temporal relationship between hyperuricemia and obesity, and its association with future risk of type 2 diabetes.

SUBJECTS/METHODS

This study examined two longitudinal cohorts totally including 17,044 subjects from China with an average of 6.0 years follow-up. Measurements of body mass index (BMI), waist circumference (WC), percentage of body fat and fasting serum uric acid were obtained at two time points. Cross-lagged panel and mediation analysis were used to examine the temporal relationship between hyperuricemia and obesity, and the association of this temporal relationship with follow-up diabetes.

RESULTS

In combined data of the two cohorts, the cross-lagged path coefficient (β₁ = 0.121; 95% confidence interval (CI): 0.108-0.135) from baseline uric acid to the follow-up BMI was significantly greater than the path coefficient (β₂ = 0.055, 95% CI: 0.038-0.072) from baseline BMI to the follow-up uric acid (P = 8.14e^-10 for the difference between β₁ and β₂) with adjustment for covariates. The separate cross-lagged path models of uric acid with WC and percentage of body fat showed temporal patterns similar to that noted for uric acid with BMI. Further, the path coefficient (β₁) from baseline uric acid to follow-up BMI in the group with diabetes was significantly greater than without diabetes (P = 0.003 for the difference of β₁s in the two groups). BMI partially mediated the association of uric acid with risk of diabetes, and the percentage of mediated-association was estimated at 20.3% (95% CI: 15.7-24.8%). Results of these analyses in the combined data were consistent with those in the two cohorts, respectively.

CONCLUSIONS

These findings indicated that increased uric acid levels probably associated with obesity and type 2 diabetes, and more definite research is needed to define any role for uric acid in relation to these diseases.