Towards the physiological function of uric acid

Effects of uric acid on oxidative stress in vascular smooth muscle cells

Hyperuricemia during hypertension is associated with aberrant vascular functions and increased oxidative stress, which affects endothelial dysfunction. Nevertheless, the molecular mechanisms underlying the effects of uric acid on vascular smooth muscle cells (VSMCs) through oxidative stress remain unclear. The aim of the present study was to investigate the dose- and time-dependent effects of uric acid on oxidative stress and p53 protein expression in VSMCs. VSMCs were incubated with various concentrations of uric acid (0-50 mg/dl) for different time periods (1-24 h). Thiobarbituric acid reactive substances (TBARs), protein carbonylation and nitric oxide (NO) levels were determined using appropriate assay kits. Superoxide anion release was detected using the Görlach method. Western blotting was performed to determine the protein expression levels of p53. The findings demonstrated that the application of uric acid led to an increase in protein carbonylation and superoxide anion levels while causing a decrease in NO levels. Conversely, no significant effect was observed on TBARS levels. Additionally, it was observed that high concentrations of uric acid suppressed p53 expression at 6, 12 and 24 h. The present study provided evidence that the influence of uric acid on oxidative stress was more closely associated with time than dose; however, not all effects observed were strictly time-dependent.

Plasma albumin, bilirubin, and uric acid and the subsequent risk of cancer: a case-cohort study in the Japan Public Health Center-based Prospective Study

Several epidemiologic studies have investigated the circulating levels of albumin, bilirubin, and uric acid (UA) in relation to cancer risk; however, they have provided equivocal evidence. In this prospective case-cohort study, we measured the plasma levels of albumin, bilirubin, and UA and investigated their association with cancer incidence in 3584 case patients and 4270 randomly selected participants with a median follow-up of 15.8 years. The adjusted hazard ratios (HRs) and 95% CIs of total cancer for the highest quartile (Q4) versus lowest quartile (Q1) was 0.77 (95% CI, 0.67-0.90; P <.001 for trend) for albumin. This association was attenuated after excluding liver cancer cases with lower plasma albumin levels. Plasma bilirubin levels were positively related to liver cancer but inversely to total cancer after excluding liver cancer with, for Q4 versus Q1, an adjusted HR of 0.86 (95% CI, 0.74-0.99; P = .015 for trend). Plasma UA levels were not dose-responsively associated with total cancer risk. Higher plasma bilirubin levels were associated with a decreased risk of total cancer after excluding liver cancer, which is likely attributed to the antioxidant properties of bilirubin.

Effect of uric acid on lipid metabolism assessed via restricted cubic splines: A new insight

Background

Hyperuricemia can promote both blood lipids and non-alcoholic fatty liver disease (NAFLD). However, the role of the entire uric acid (UA) span, especially low concentrations below hyperuricemia, on lipid metabolism remains unclear.

Methods

A cross-sectional study was designed. Data on the age, sex, UA, triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) of 1977 participants, who underwent physical examination, were collected. NAFLD and non-alcoholic fatty pancreas disease (NAFPD) were diagnosed using abdominal ultrasound. Restricted cubic splines (RCS) linear regression model was used to evaluate the effect of the UA span on TG, TC, HDL, and LDL, respectively. RCS logistic regression model was employed to evaluate the effect of the UA span on NAFLD and NAFPD.

Results

RCS linear regression model showed that TG was negatively correlated with UA at first, then exhibiting a positive correlation. Meanwhile, HDL was positively correlated with UA at first, then negatively correlated. There was a positive linear correlation between TC and UA (P for nonlinear = 0.578) and a positive nonlinear correlation between LDL and UA (P for nonlinear = 0.021). RCS logistic regression model showed that NAFLD and NAFPD were negatively correlated with UA at first and then positively correlated with UA.

Conclusion

our study showed that the entire UA span has a J-shaped effect on some lipids, NAFLD, and NAFPD. Besides, TG and HDL, compared with TC or LDL, may better reflect the status of NAFLD and NAFPD.

Long-term relatively high dietary manganese intake could decrease the risk of hyperuricemia: Twelve-year distinct dietary manganese consumption trajectories and the China Health and Nutrition Survey

BACKGROUND AND AIM

Currently, the relationship between dynamic changes in dietary manganese (Mn) intake and risk of hyperuricemia (HU) is still unclear. This study aimed to identify dietary Mn consumption trajectories in the Chinese adults and assess their relation with the risk of HU.

METHODS AND RESULTS

Cohort data from the China Health and Nutrition Survey (CHNS) 1997-2009 were employed in this study. Overall, 6886 adult participants were included. Participants were designated into subgroups based on the trajectories of dietary Mn consumption by sex. Cox proportional hazard models were used to explore the associations between different trajectories and the risk of HU. For men, compared with low stable trajectory group, moderate to high trajectory group was significantly related to reduced risk of HU (HR = 0.61, 95% CI: 0.38 to 0.98) with adjustment for covariates. TC, HDL-C, ApoB, and TG exerted partial regulation function between trajectories and HU. For women, compared with low stable trajectory group, high stable trajectory group was significantly related to reduced risk of HU (HR = 0.76, 95% CI: 0.60 to 0.95) with adjustment for covariates. Similarly, TC, HDL-C, ApoB, and ApoA exerted partial regulation function between trajectories and HU.

CONCLUSIONS

Long-term relatively high dietary Mn consumption may have a protective effect against HU in Chinese adults. The differences in HU-related factors among different dietary Mn intake trajectories partially regulated the association between these trajectories and HU.

Association between uric acid and the risk of hemorrhagic transformation in patients with acute ischemic stroke: a systematic review and meta-analysis

Background

The relationship between hemorrhagic transformation (HT) and uric acid (UA) remains controversial. This study aimed to investigate the relationship between UA concentrations and the risk of HT following acute ischemic stroke (AIS).

Methods

Electronic databases were searched for studies on HT and UA from inception to October 31, 2023. Two researchers independently reviewed the studies for inclusion. STATA Software 16.0 was used to compute the standardized mean difference (SMD) and 95% confidence interval (CI) for the pooled and post-outlier outcomes. Heterogeneity was evaluated using the I2 statistic and the Galbraith plot. Additionally, sensitivity analysis was performed. Lastly, Begg's funnel plot and Egger's test were used to assess publication bias.

Results

A total of 11 studies involving 4,608 patients were included in the meta-analysis. The pooled SMD forest plot (SMD = -0.313, 95% CI = -0.586--0.039, p = 0.025) displayed that low UA concentrations were linked to a higher risk of HT in post-AIS patients. However, heterogeneity (I2 = 89.8%, p < 0.001) was high among the studies. Six papers fell outside the Galbraith plot regression line, and there exclusive resulted in the absence of heterogeneity (I2 = 52.1%, p = 0.080). Meanwhile, repeated SMD analysis (SMD = -0.517, 95% CI = -0.748--0.285, p = 0.000) demonstrated that the HT group had lower UA concentrations. Finally, Begg's funnel plot and Egger's test indicated the absence of publication bias in our meta-analysis.

Conclusion

This meta-analysis illustrated a substantial connection between UA concentrations and HT, with lower UA concentrations independently linked with a higher risk of HT post-AIS. These results lay a theoretical reference for future studies.Systematic review registration:https://www.crd.york.ac.uk/PROSPERO/CRD42023485539.

Randomised, double-blind, placebo-controlled study evaluating the effect of allopurinol on the risk of cardiovascular events in patients with high and very high cardiovascular risk, including the presence of long-COVID-19 syndrome: the ALL-VASCOR study protocol

INTRODUCTION

Numerous studies, but not all, have suggested a positive effect of allopurinol on the cardiovascular system. The randomised, double-blind, placebo-controlled study evaluating the effect of allopurinol on the risk of cardiovascular events in patients with high and very high cardiovascular risk, including the presence of long-COVID-19 syndrome (ALL-VASCOR) study aims to evaluate the efficacy of allopurinol therapy for improving cardiovascular outcomes in patients at high and very high cardiovascular risk excluding ischaemic heart disease. This is particularly important due to the high cost of cardiovascular disease treatment and its status as one of the leading causes of mortality.

METHODS AND ANALYSIS

The ALL-VASCOR study is a randomised, double-blind, placebo-controlled, multicentre trial that examines the effect of allopurinol therapy (200-500 mg of allopurinol daily) versus an equivalent dose of placebo on the risk of cardiovascular events in 1116 patients aged 40-70 with serum uric acid levels above 5 mg/dL at high and very high risk of cardiovascular disease. The ALL-VASCOR study will also assess the occurrence of long-COVID-19 syndrome. The study will measure primary and secondary as well as additional endpoints and the planned intervention will end on 31 July 2028 unless advised otherwise by the Safe Monitoring Board or other applicable authorities. Participant recruitment is planned to begin in March 2024 in Poland.

ETHICS AND DISSEMINATION

The study was ethically approved by the Bioethics Committee of Poznan University of Medical Sciences (No 03/23, 12 January 2023). The results are expected after 2028 and will be disseminated in peer-reviewed journals and at international conferences.

PROTOCOL VERSION NUMBER

01-15 November 2022.

TRIAL REGISTRATION NUMBER

EudraCT: 2022-003573-32, 27 October 2022, ClinicalTrials: NCT05943821, 13 July 2023.

Recent Progress in Organic Electrochemical Transistor-Structured Biosensors

The continued advancement of organic electronic technology will establish organic electrochemical transistors as pivotal instruments in the field of biological detection. Here, we present a comprehensive review of the state-of-the-art technology and advancements in the use of organic electrochemical transistors as biosensors. This review provides an in-depth analysis of the diverse modification materials, methods, and mechanisms utilized in organic electrochemical transistor-structured biosensors (OETBs) for the selective detection of a wide range of target analyte encompassing electroactive species, electro-inactive species, and cancer cells. Recent advances in OETBs for use in sensing systems and wearable and implantable applications are also briefly introduced. Finally, challenges and opportunities in the field are discussed.

Causality between serum uric acid and diabetic microvascular complications - a mendelian randomization study

BACKGROUND

The aim of this study was to investigate whether a causal relationship exists between serum uric acid (SUA) and diabetic microvascular complications using a two-sample Mendelian randomization (MR) method.

METHODS

We used the MR approach, utilizing genome-wide association study (GWAS) summary statistics, to estimate the causal effect of SUA on diabetic microvascular complications in European individuals. The summary statistical data of SUA were obtained from the open database (IEU OPEN GWAS PROJECT) (p < 5 × 10- 8), and data on diabetic microvascular complications (diabetic nephropathy, diabetic neuropathy, diabetic retinopathy) were obtained from the FinnGen consortium. F-statistics were calculated to assess the correlation between instrumental variables (IVs) and SUA, and single nucleotide polymorphisms (SNPs) associated with confounders or outcomes were excluded by consulting the PhenoScanner database. Inverse variance weighting (IVW) was used for primary estimation, and MR‒Egger, weighted median (WM), and Mendelian randomization pleiotropy residuals sum and outliers (MR-PRESSO) were used for additional assessment. Heterogeneity was assessed using the Cochran's Q test, and polytropy was assessed using the MR‒Egger intercept.

RESULTS

MR analysis revealed a causal relationship between a genetically predicted increase in SUA and diabetic nephropathy [OR = 1.32, 95%(CI) = 1.07-1.63, p = 0.008]. The results were consistent with those after MR-PRESSO [OR = 1.30, 95%(CI) = 1.07-1.58, p = 0.008]. There was a causal relationship between type 2 diabetes mellitus (T2DM) and renal complication IVW [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.049]. These results were consistent with those after MR-PRESSO [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.050]. There was no significant causal relationship between the genetically predicted increase in SUA and diabetic retinopathy [OR 1.09, 95%(CI) = 0.94-1.26, p = 0.249] or diabetic neuropathy [OR = 1.08, 95%(CI) = 0.84-1.40, p = 0.549].

CONCLUSIONS

This MR analysis suggests a causal relationship between genetically predicted uric acid increases and diabetic microvascular complications. A significant causal relationship exists between SUA and diabetic nephropathy but not between SUA and diabetic retinopathy or diabetic neuropathy.

Altered Serum Proteins Suggest Inflammation, Fibrogenesis and Angiogenesis in Adult Patients with a Fontan Circulation

Previous omics research in patients with complex congenital heart disease and single-ventricle circulation (irrespective of the stage of palliative repair) revealed alterations in cardiac and systemic metabolism, inter alia abnormalities in energy metabolism, and inflammation, oxidative stress or endothelial dysfunction. We employed an affinity-proteomics approach focused on cell surface markers, cytokines, and chemokines in the serum of 20 adult Fontan patients with a good functioning systemic left ventricle, and we 20 matched controls to reveal any specific processes on a cellular level. Analysis of 349 proteins revealed 4 altered protein levels related to chronic inflammation, with elevated levels of syndecan-1 and glycophorin-A, as well as decreased levels of leukemia inhibitory factor and nerve growth factor-ß in Fontan patients compared to controls. All in all, this means that Fontan circulation carries specific physiological and metabolic instabilities, including chronic inflammation, oxidative stress imbalance, and consequently, possible damage to cell structure and alterations in translational pathways. A combination of proteomics-based biomarkers and the traditional biomarkers (uric acid, γGT, and cholesterol) performed best in classification (patient vs. control). A metabolism- and signaling-based approach may be helpful for a better understanding of Fontan (patho-)physiology. Syndecan-1, glycophorin-A, leukemia inhibitory factor, and nerve growth factor-ß, especially in combination with uric acid, γGT, and cholesterol, might be interesting candidate parameters to complement traditional diagnostic imaging tools and the determination of traditional biomarkers, yielding a better understanding of the development of comorbidities in Fontan patients, and they may play a future role in the identification of targets to mitigate inflammation and comorbidities in Fontan patients.

Study on plasma metabolomics profiling of depression in Chinese community-dwelling older adults based on untargeted LC/GC‒MS

Depression is a serious psychiatric illness that causes great inconvenience to the lives of elderly individuals. However, the diagnosis of depression is somewhat subjective. Nontargeted gas chromatography (GC)/liquid chromatography (LC)-mass spectrometry (MS) was used to study the plasma metabolic profile and identify objective markers for depression and metabolic pathway variation. We recruited 379 Chinese community-dwelling individuals aged ≥ 65. Plasma samples were collected and detected by GC/LC‒MS. Orthogonal partial least squares discriminant analysis and a heatmap were utilized to distinguish the metabolites. Receiver operating characteristic curves were constructed to evaluate the diagnostic value of these differential metabolites. Additionally, metabolic pathway enrichment was performed to reveal metabolic pathway variation. According to our standard, 49 people were included in the depression cohort (DC), and 49 people age- and sex-matched individuals were included in the non-depression cohort (NDC). 64 metabolites identified via GC‒MS and 73 metabolites identified via LC‒MS had significant contributions to the differentiation between the DC and NDC, with VIP values > 1 and p values < 0.05. Three substances were detected by both methods: hypoxanthine, phytosphingosine, and xanthine. Furthermore, 1-(sn-glycero-3-phospho)-1D-myo-inositol had the largest area under the curve (AUC) value (AUC = 0.842). The purine metabolic pathway is the most important change in metabolic pathways. These findings show that there were differences in plasma metabolites between the depression cohort and the non-depression cohort. These identified differential metabolites may be markers of depression and can be used to study the changes in depression metabolic pathways.

Comparison of serum uric acid levels between localised prostate cancer patients and a control group

AIM

The aim of this study is to find out whether serum uric acid levels in patients with localised prostate cancer differ from patients with lower urinary tract symptoms without carcinoma prostate.

MATERIAL AND METHODS

We performed a prospective observational study of 60 patients having age ⩾ 50 years with c/o lower urinary tract symptoms( LUTS) evaluated by digital rectal examination (DRE), prostate-specific antigen (PSA) level and ultrasonography kidney, ureter, bladder (USG KUB) prostate and patients who were suspicious for carcinoma prostate underwent trans rectal ultrasonography (TRUS) biopsy of prostate. Patients with biopsy s/o prostate cancer were evaluated for metastasis and localised cancer patients were considered as CASE group. Patients with negative biopsy and other patients having LUTS were considered as CONTROL group. The age, serum uric acid level, PSA value, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cell (WBC) count were measured. Serum uric acid level was compared in both the groups.

RESULTS

The mean serum uric acid level was lower in prostate cancer group (4.77 mg/dl) than control group (6.22 mg/dl) that was statistically significant (p < 0.001). The mean PSA value was 7.43 ng/dl in cancer group and 2.72 ng/dl in control group. (p < 0.001). The mean C-reactive protein (CRP) values were 1.32 and 0.45 respectively (p < 0.001), erythrocyte sedimentation rate (ESR) were found 21 and 10.5 respectively (p < 0.001)and total leucocyte counts (TLC) were found 6.450 and 5.120 respectively (p < 0.001). All were statistically significant (p < 0.05).

CONCLUSION

The serum uric acid levels measured in localised prostate cancer patients were found to be reduced compared to the control group and inflammatory markers were found to be increased. Decreased levels of serum uric acid and increased levels of inflammatory markers were determined as risk factors for prostate cancer.

Uric acid-lowering effects of sodium-glucose cotransporter 2 inhibitors for preventing cardiovascular events and mortality: A systematic review and meta-analysis

BACKGROUND

To evaluate the effect of a 1 mg/dl reduction in uric acid (UA) on cardiovascular events and mortality in patients treated with sodium-glucose cotransporter 2 (SGLT2) inhibitors.

RESEARCH DESIGN AND METHODS

We performed a systematic review of the MEDLINE and EMBASE databases searched up to 30 June 2023 (PROSPERO, CRD42022355479) to identify large-scale SGLT2 inhibitor trials. Random-effects meta-analyses were used to pool the estimates.

RESULTS

In total, five SGLT2 inhibitor trials (31 535 patients, 54% with heart failure) were analysed. Over a median follow-up of 2.2 years, the mean reduction in UA was -0.79 mg/dl (95% confidence interval (CI), -1.03 to -0.54). Every 1 mg/dl reduction in UA was associated with a significantly lower risk of a composite of cardiovascular death and hospitalization for heart failure [hazard ratio, 0.64 (95% CI, 0.46-0.88)] and hospitalization for heart failure (0.68; 95% CI, 0.62-0.74), with a similar risk of mortality.

CONCLUSIONS

SGLT2 inhibitors reduced UA levels and cardiovascular events independently of heart failure status.

Inflammatory response in dairy cows caused by heat stress and biological mechanisms for maintaining homeostasis

Climate change increases global temperatures, which is lethal to both livestock and humans. Heat stress is known as one of the various livestock stresses, and dairy cows react sensitively to high-temperature stress. We aimed to better understand the effects of heat stress on the health of dairy cows and observing biological changes. Individual cows were divided into normal (21-22 °C, 50-60% humidity) and high temperature (31-32 °C, 80-95% humidity), respectively, for 7-days. We performed metabolomic and transcriptome analyses of the blood and gut microbiomes of feces. In the high-temperature group, nine metabolites including linoleic acid and fructose were downregulated, and 154 upregulated and 72 downregulated DEGs (Differentially Expressed Genes) were identified, and eighteen microbes including Intestinimonas and Pseudoflavonifractor in genus level were significantly different from normal group. Linoleic acid and fructose have confirmed that associated with various stresses, and functional analysis of DEG and microorganisms showing significant differences confirmed that high-temperature stress is related to the inflammatory response, immune system, cellular energy mechanism, and microbial butyrate production. These biological changes were likely to withstand high-temperature stress. Immune and inflammatory responses are known to be induced by heat stress, which has been identified to maintain homeostasis through modulation at metabolome, transcriptome and microbiome levels. In these findings, heat stress condition can trigger alteration of immune system and cellular energy metabolism, which is shown as reduced metabolites, pathway enrichment and differential microbes. As results of this study did not include direct phenotypic data, we believe that additional validation is required in the future. In conclusion, high-temperature stress contributed to the reduction of metabolites, changes in gene expression patterns and composition of gut microbiota, which are thought to support dairy cows in withstanding high-temperature stress via modulating immune-related genes, and cellular energy metabolism to maintain homeostasis.

A facile, low-cost bimetallic iron-nickel MOF nanozyme-propelled ratiometric fluorescent sensor for highly sensitive and selective uric acid detection and its smartphone application

As a kind of well-known disease biomarker, uric acid (UA) is closely associated with normal metabolism and health. Despite versatile nanozymes facilitating the analysis of UA, most previous works could only generate single-signal outputs with unsatisfactory detection performance. Exploring a novel ratiometric fluorescent UA sensor with high sensitivity, reliability and portable sensing ability based on facile, low-cost nanozymes is still challenging. Herein, we report the first metal-organic-framework (MOF) nanozyme-originated ratiometric fluorescent UA sensor based on Fe3Ni-MOF-NH2 propelled UA/uricase/o-phenylenediamine tandem catalytic reaction. Different from previous reports, the peroxidase-like property and fluorescence of Fe3Ni-MOF-NH2 were simultaneously employed. In the absence of UA, only the MOF's fluorescence at 430 nm (FI430) can be observed, while the addition of UA will initiate UA/uricase catalytic reaction, and the generated H2O2 could oxidize o-phenylenediamine into highly fluorescent 2,3-diaminophenazine (DAP) (emission at 565 nm, FI565) under the catalysis of the MOF nanozyme. Coincidently, MOF's fluorescence can be quenched by DAP via the inner filter effect, resulting in a low FI430 value and high FI565 value, respectively. Therefore, H2O2 and UA can be alternatively detected through monitoring the above contrary fluorescence changes. The limit of detection for UA is 24 nM, which is much lower than those in most previous works, and the lowest among nanozyme-based ratiometric fluorescent UA sensors reported to date. Moreover, the portable sensing of UA via smartphone-based RGB analysis was facilely achieved by virtue of the above nanozyme-propelled tandem catalytic system, and MOF nanozyme-based molecular contrary logic pairs were further implemented accordingly.

A cross-sectional analysis of the relationship between ischemic stroke and uric acid in young people in highland areas

Objective

To investigate the relationship between serum uric acid (SUA) levels and ischemic stroke in young patients in the Ganzi Tibetan plateau area.

Methods

A cross-sectional survey was undertaken from January 2020 to June 2023 involving young patients (age: 15-45 years) diagnosed with ischemic stroke. The survey was conducted at the Department of Internal Medicine of the People's Hospital of Derong County, Ganzi Prefecture. The participants underwent a comprehensive assessment, including questionnaire surveys, physical examinations, laboratory tests, and head computed tomography (CT) examinations. Based on the tertiles of serum uric acid (SUA) levels, the patients were stratified into three groups. Furthermore, stroke severity was classified into mild (1-4 points), moderate (5-15 points), and severe (>15 points) categories using the National Institute of Health Stroke Scale.

Results

The severe stroke group exhibited higher levels of age, glucose, systolic blood pressure, serum triglyceride, low-density lipoprotein cholesterol, and serum uric acid (SUA) compared to the mild stroke group (P < 0.05). Furthermore, the likelihood of male sex, advanced age, smoking, and a family history of stroke, diabetes mellitus, and heart disease were significantly elevated in the severe stroke group compared to the moderate stroke group (P < 0.05). Multivariate logistic regression analysis conducted on young adults residing in highland areas revealed a significant association between SUA levels and the risk of stroke.

Conclusion

Elevated SUA levels serve as a distinct risk factor for the development of a major stroke in young patients in highland areas. At SUA levels of 320.56 mol/L, the risk of a moderate-to-severe stroke is noticeably elevated.

Multiomic approach and Mendelian randomization analysis identify causal associations between blood biomarkers and subcortical brain structure volumes

Alterations in subcortical brain structure volumes have been found to be associated with several neurodegenerative and psychiatric disorders. At the same time, genome-wide association studies (GWAS) have identified numerous common variants associated with brain structure. In this study, we integrate these findings, aiming to identify proteins, metabolites, or microbes that have a putative causal association with subcortical brain structure volumes via a two-sample Mendelian randomization approach. This method uses genetic variants as instrument variables to identify potentially causal associations between an exposure and an outcome. The exposure data that we analyzed comprised genetic associations for 2994 plasma proteins, 237 metabolites, and 103 microbial genera. The outcome data included GWAS data for seven subcortical brain structure volumes including accumbens, amygdala, caudate, hippocampus, pallidum, putamen, and thalamus. Eleven proteins and six metabolites were found to have a significant association with subcortical structure volumes, with nine proteins and five metabolites replicated using independent exposure data. We found causal associations between accumbens volume and plasma protease c1 inhibitor as well as strong association between putamen volume and Agouti signaling protein. Among metabolites, urate had the strongest association with thalamic volume. No significant associations were detected between the microbial genera and subcortical brain structure volumes. We also observed significant enrichment for biological processes such as proteolysis, regulation of the endoplasmic reticulum apoptotic signaling pathway, and negative regulation of DNA binding. Our findings provide insights to the mechanisms through which brain volumes may be affected in the pathogenesis of neurodevelopmental and psychiatric disorders and point to potential treatment targets for disorders that are associated with subcortical brain structure volumes.

Uric Acid: A Translational Journey in Cerebroprotection That Spanned Preclinical and Human Data

Uric acid (UA) is a strong endogenous antioxidant that neutralizes the toxicity of peroxynitrite and other reactive species on the neurovascular unit generated during and after acute brain ischemia. The realization that a rapid reduction of UA levels during an acute ischemic stroke was associated with a worse stroke outcome paved the way to investigate the value of exogenous UA supplementation to counteract the progression of redox-mediated ischemic brain damage. The long translational journey for UA supplementation recently reached a critical milestone when the results of the multicenter NIH stroke preclinical assessment network (SPAN) were reported. In a novel preclinical paradigm, 6 treatment candidates including UA supplementation were selected and tested in 6 independent laboratories following predefined criteria and strict methodological rigor. UA supplementation was the only intervention in SPAN that exceeded the prespecified efficacy boundary with male and female animals, young mice, young rats, aging mice, obese mice, and spontaneously hypertensive rats. This unprecedented achievement will allow UA to undergo clinical testing in a pivotal clinical trial through a NIH StrokeNet thrombectomy endovascular platform created to assess new treatment strategies in patients treated with mechanical thrombectomy. UA is a particularly appealing adjuvant intervention for mechanical thrombectomy because it targets the microcirculatory hypoperfusion and oxidative stress that limits the efficacy of this therapy. This descriptive review aims to summarize the translational development of UA supplementation, highlighting those aspects that likely contributed to its success. It includes having a well-defined target and mechanism of action, and an approach that simultaneously integrated rigorous preclinical assessment, with epidemiologic and preliminary human intervention studies. Validation of the clinical value of UA supplementation in a pivotal trial would confirm the translational value of the SPAN paradigm in preclinical research.

Longitudinal metabolomics integrated with machine learning identifies novel biomarkers of gestational diabetes mellitus

BACKGROUND

Evidence from longitudinal studies is crucial to enhance our understanding of the role of metabolites in the progression of gestational diabetes mellitus (GDM). Herein, a longitudinal untargeted metabolomic study was conducted to reveal the metabolomic profiles and biomarkers associated with the progression of GDM, and characterize the changing patterns of metabolites.

METHODS

We collected serum samples at three trimesters from 30 patients with GDM and 30 healthy Chinese pregnant women with pre-pregnancy BMI, age, and parity matched, and untargeted metabolomic analysis was performed, followed by machine learning approaches that integrated bootstrap and LASSO. Cluster analysis was conducted to elucidate the patterns of metabolite changes. Pathway analyses were conducted to gain insights into the underlying pathways involved.

RESULTS

A total of 32 metabolites, mainly belonging to amino acid and its derivatives, were significantly associated with GDM across three trimesters, and were clustered into three distinct patterns. Metabolites belonging to phosphatidylcholines, lysophosphatidylcholines, lysophosphatidic acids, and lysophosphatidylethanolamines were consistently upregulated, and 2,3-Dihydroxypropyl dihydrogen phosphate was downregulated in GDM group. Amino acid-related, glycerophospholipid, and vitamin B6 metabolism were enriched in multiple trimesters. The levels of allantoic acid, which was positively correlated with blood glucose, was consistently higher in GDM patients and exhibited good discriminatory ability for GDM in the early and mid-pregnancy.

CONCLUSION

We identified and characterized distinct patterns of metabolites associated with GDM throughout pregnancy, and found that allantoic acid was a potential biomarker for early diagnosis of GDM.

Untargeted metabolomics reveals dynamic changes in metabolic profiles of rat supraspinatus tendon at three different time points after diabetes induction

Objective

To investigate the dynamic changes of metabolite composition in rat supraspinatus tendons at different stages of diabetes by untargeted metabolomics analysis.

Methods

A total of 80 Sprague-Dawley rats were randomly divided into normal (NG, n = 20) and type 2 diabetes mellitus groups (T2DM, n = 60) and subdivided into three groups according to the duration of diabetes: T2DM-4w, T2DM-12w, and T2DM-24w groups; the duration was calculated from the time point of T2DM rat model establishment. The three comparison groups were set up in this study, T2DM-4w group vs. NG, T2DM-12w group vs. T2DM-4w group, and T2DM-24w group vs. T2DM-12w group. The metabolite profiles of supraspinatus tendon were obtained using tandem mass spectrometry. Metabolomics multivariate statistics were used for metabolic data analysis and differential metabolite (DEM) determination. The intersection of the three comparison groups' DEMs was defined as key metabolites that changed consistently in the supraspinatus tendon after diabetes induction; then, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed.

Results

T2DM-4w group vs. NG, T2DM-12w group vs. T2DM-4w group, and T2DM-24w group vs. T2DM-12w group detected 94 (86 up-regulated and 8 down-regulated), 36 (13 up-regulated and 23 down-regulated) and 86 (24 up-regulated and 62 down-regulated) DEMs, respectively. Seven key metabolites of sustained changes in the supraspinatus tendon following induction of diabetes include D-Lactic acid, xanthine, O-acetyl-L-carnitine, isoleucylproline, propoxycarbazone, uric acid, and cytidine, which are the first identified biomarkers of the supraspinatus tendon as it progresses through the course of diabetes. The results of KEGG pathway enrichment analysis showed that the main pathway of supraspinatus metabolism affected by diabetes (p < 0.05) was purine metabolism. The results of the KEGG metabolic pathway vs. DEMs correlation network graph revealed that uric acid and xanthine play a role in more metabolic pathways.

Conclusion

Untargeted metabolomics revealed the dynamic changes of metabolite composition in rat supraspinatus tendons at different stages of diabetes, and the newly discovered seven metabolites, especially uric acid and xanthine, may provide novel research to elucidate the mechanism of diabetes-induced tendinopathy.

Serum uric acid is independently associated with hypertension in patients with polymyositis and dermatomyositis

Serum uric acid (UA), as an antioxidant, has been associated with hypertension in the general population. Hypertension is highly prevalent in patients with polymyositis and dermatomyositis (PM/DM). Owning elevated levels of reactive oxygen species, patients with PM/DM have lower concentrations of UA in comparison with healthy people. We explored a potential association between UA levels and hypertension in PM/DM and evaluated whether this association is independent of hypertension risk factors, PM/DM characteristics and relevant drugs. A total of 472 PM/DM patients were assessed. UA and related laboratory data were measured. Demographic, hypertension-related factors, PM/DM characteristics and drug use were assessed as potential covariates. Results were analyzed using logistic models to test the independence of the association between UA and hypertension. UA levels were higher in hypertension subjects compared to non-hypertensive PM/DM patients [284.70 (239.93-357.38) vs 264.00(222.50-322.75), p = .017]. When adjusted for hypertension risk factors, PM/DM characteristics and drugs, the odds of being a hypertensive PM/DM patient per 1 μmol/L UA increase were significantly increased: odds ratio = 1.473 (95% confidence interval:1.063-2.042, p = .020). This cross-sectional study suggests that UA levels are independently associated with hypertension in PM/DM patients.

Relationship between evacuation after the Great East Japan Earthquake and new-onset hyperuricemia: A 7-year prospective longitudinal study of the Fukushima Health Management Survey

INTRODUCTION

On March 11, 2011, the Great East Japan Earthquake occurred in Japan, with a nuclear accident subsequently occurring at the Fukushima Daiichi Nuclear Power Plant. The disaster forced many evacuees to change particular aspects of their lifestyles. However, the effect of evacuation on the new-onset of hyperuricemia have not been sufficiently elucidated. This study assessed the association between evacuation and new-onset hyperuricemia after the earthquake based on the Fukushima Health Management Survey from a lifestyle and socio-psychological perspective.

MATERIALS AND METHODS

This is a 7-year prospective longitudinal study included 18,140 residents (6,961 men and 11,179 women) with non-hyperuricemia who underwent both the Comprehensive Health Check and the Mental Health and Lifestyle Survey in fiscal year 2011. Associations between new-onset hyperuricemia and lifestyle- and disaster-related factors, including evacuation, were estimated using a Cox proportional hazards regression model analysis. Hyperuricemia was defined as uric acid levels > 7.0 mg/dL for men and > 6.0 mg/dL for women.

RESULTS

During a median follow-up of 4.3 years, 2,996 participants (1,608 men, 23.1%, 1,388 women, 12.4%) newly developed hyperuricemia. Significant associations were observed between evacuation and onset of hyperuricemia in women (adjusted hazard ratio 1.18, 95% confidence interval, 1.05-1.32, p = 0.007), but not in men (adjusted hazard ratio 1.11, 95% confidence interval, 0.99-1.24, p = 0.067).

DISCUSSION

Evacuation after a natural disaster is an independent risk factor for the new-onset of hyperuricemia in women. The possibility of hyperuricemia developing in response to natural disasters should be considered.

Semiempirical Approach to the Fukui Function Analysis of Uric Acid under Different pH Conditions

Analytic Fukui functions calculated at a first-principles level are combined with experimental pKa values and the calculation of tautomerization energies to obtain the effective regioselectivity of uric acid toward electron-transfer reactions under different pH conditions. Second-order electron binding energies are also computed to determine which of the tautomers is more likely to participate in the electron transfer. A comparison of vertical and adiabatic proton detachment energies allows us to conclude that tautomerization is not mediating deprotonation and that two monoanionic species are of comparable relevance. The main difference between these monoanionic species is the ring that has been deprotonated. Both monoanionic species are produced from a single neutral tautomer and mainly produce a single dianionic tautomer. As a method for the analysis of systems affected by pH such as uric acid, we propose to plot condensed Fukui functions versus pH, allowing us to draw the effect of pH on the regioselectivity of electron transfer in a single image.

Probiotic Bacillus subtilis contributes to the modulation of gut microbiota and blood metabolic profile of hosts

Probiotic Bacillus subtilis has beneficial efficacy on host's health. The microbiota-gut-blood system (MGBS) plays a crucial role in maintaining the homeostasis of hosts. However, the mechanism by which the probiotic B. subtilis positively acts on the MGBS of hosts remains unclear. Herein, we used an interspecies animal model to explore the causal associations between this bacterium and the micro-ecology balance and circulatory homeostasis of hosts. Results showed that the body weight of hosts significantly increased after probiotic B. subtilis supplementation (P < 0.05). Enterococcus was found to be the most important microbial marker causing the intergroup differences observed herein, and its relative abundance remarkably increased after B. subtilis supplementation. In addition, the supplementation of B. subtilis induced significant alterations in the levels of circulating metabolites, such as serine, arginine, adenine, uric acid, and pyridoxal (P < 0.05), indicating that B. subtilis modulated the metabolic profile of blood circulation in the host. The metabolisms of amino acids, purine, and vitamin B were the primary pathways modulated by B. subtilis. In conclusion, probiotic B. subtilis substantially introduced subtle but positive changes in the host's gut microbiome, and it promoted the physiological activity of the host by modulating circulating metabolites. The study provides a theoretical reference for the application of probiotic B. subtilis to improve the health state of specific populations.

Relationship between serum uric acid and estimated glomerular filtration rate in adolescents aged 12-19 years with different body mass indices: a cross-sectional study

Background

Globally, chronic kidney disease (CKD) is a growing public health concern. Serum uric acid (SUA) is an easily detectable and readily available biochemical indicator that has long been recognized as an independent risk factor for CKD. In addition, studies have indicated a potential relationship between SUA and body mass index (BMI). However, studies on the effect of SUA levels on the estimated glomerular filtration rate (eGFR) in adolescents with different BMIs are very rare.

Methods

Weighted multiple regression analysis was used to estimate the independent relationship between SUA and log-transformed eGFR. Additionally, we used a weighted generalized additive model and smooth curve fitting to describe the nonlinear relationships in the subgroup analysis.

Results

First, SUA was negatively associated with log-transformed eGFR even after adjusting for all covariates (β=-0.0177, 95% CI: -0.0203-0.0151, P<0.0001). Second, the results of the stratified analysis found that after adjusting for all covariates, the decrease in log-transformed eGFR due to changes in per SUA levels (Per 1, mg/dL increase) was elevated in female adolescents (β=-0.0177, 95% CI: -0.0216, -0.0138, P<0.0001), adolescents aged 12-15 years (β=-0.0163, 95% CI: -0.0200, -0.0125, P<0.0001) and black (β=-0.0199, 95% CI: -0.0251, -0.0148, P<0.0001) adolescents. Furthermore, we found that adolescents with a higher BMI had higher SUA levels, and the effect of SUA on eGFR was significantly higher in underweight adolescents (β=-0.0386, 95% CI: (-0.0550, -0.0223), P<0.0001).

Conclusion

SUA was negatively associated with the eGFR in adolescents aged 12-19 years. Furthermore, we found for the first time that SUA affects the eGFR differently in adolescents with different BMIs. This effect was particularly significant in underweight adolescents.

Uric acid levels and their association with vascular dementia and Parkinson's disease dementia: a meta-analysis

OBJECTIVES

To explore the association between uric acid (UA) levels and vascular dementia (VaD) and Parkinson's disease dementia (PDD), a meta-analysis was conducted.

METHODS

The relevant studies were identified by searching PubMed, Embase, Web of Science, and Cochrane Collaboration Database up to May 2022. Pooled analysis, sensitivity analysis, and publication bias examination were all conducted. All analyses were performed by using STATA 16.

RESULTS

Twelve studies with a total of 2097 subjects were included. The pooled analysis showed that UA levels were not associated with VaD (WMD =  - 10.99 μmol/L, 95% CI (- 48.05, 26.07), P = 0.561) but were associated with PDD (WMD =  - 25.22 μmol/L, 95% CI (- 43.47, - 6.97), P = 0.007). The statistical stability and reliability were evaluated using sensitivity analysis and publication bias outcomes.

CONCLUSION

UA levels are associated with PDD but not with VaD. This study will help to strengthen our knowledge of the pathophysiologies of VaD and PDD, and promote the development of prevention and treatment strategies.

U-shaped association of serum uric acid with all-cause mortality in patients with hyperlipidemia in the United States: a cohort study

Background

Serum uric acid (SUA) interferes with lipid metabolism and is considered an independent risk factor for atherosclerosis, a major complication in patients with hyperlipidemia. However, the effects of uric acid levels on mortality in hyperlipidemic patients has yet to be sufficiently determined. In this study, we aimed to assess the association between all-cause mortality and SUA in a hyperlipidemic population.

Methods

To determine mortality rates, we obtained data for 20,038 hyperlipidemia patients from the U.S. National Health and Nutrition Examination Surveys (NHANES) 2001-2018 and National Death Index. To examine the all-cause mortality effect of SUA, multivariable Cox regression models, restricted cubic spline models, and two pairwise Cox regression models were used.

Results

Over a median follow-up of 9.4 years, a total of 2079 deaths occurred. Mortality was examined according to SUA level quintiles: <4.2, 4.3-4.9, 5.0-5.7, 5.8-6.5, and >6.6 mg/dl. In multivariable analysis using 5.8-6.5 mg/dl SUA as a reference, the hazard ratios (95% confidence interval) of all-cause mortality across the five groups were 1.24 (1.06-1.45), 1.19 (1.03-1.38), 1.07 (0.94-1.23), 1.00 (reference), and 1.29 (1.13-1.48), respectively. According to a restricted cubic spline, we noted a U-shaped relationship between SUA and all-cause mortality. The inflection point was approximately 6.30 mg/dl, with hazard ratios of 0.91 (0.85-0.97) and 1.22 (1.10-1.35) to the left and right of the inflection point, respectively. In both sexes, SUA was characterized by a U-shaped association, with inflection points at 6.5 and 6.0 mg/dl for males and females, respectively.

Conclusion

Using nationally representative NHANES data, we identified a U-shaped association between SUA and all-cause mortality in participants with hyperlipidemia.

Investigating the Effect of Cigarette Smoking on Serum Uric Acid Levels in Multiple Sclerosis Patients: A Cross Sectional Study

OBJECTIVES

The present study is aimed at determining the effect of cigarette smoking (CS) on serum uric acid (UA) levels quantitatively before and after smoking cessation among people with MS (pwMS). Additionally, a possible correlation between UA levels and both disability progression and disease severity was also investigated. A retrospective cross-sectional study was conducted using the Nottingham University Hospitals MS Clinics database. It involves 127 people with definite MS recorded when reporting the latest smoking status and the clinical diagnosis. All necessary demographics and clinical characteristics were collected. We found that smoker pwMS had significantly lower serum UA levels than non-smoker pwMS (p-value = 0.0475), and this reduction was recovered after smoking cessation (p-value = 0.0216). However, the levels of disability or disease severity were not correlated with the levels of serum UA in current smoker pwMS, measured by the expanded disability status scale (EDSS; r = -0.24; p-value = 0.38), multiple sclerosis impact scale 29 (MSIS-29; r = 0.01; p-value = 0.97) and MS severity score (MSSS; r = -0.16; p-value = 0.58), respectively. Our result suggests that the reduction in UA levels is more likely a consequence of oxidative stress triggered by many risk factors, including CS, and could be considered a potential indicator of smoking cessation. In addition, the absence of a correlation between UA levels and disease severity and disability suggests that UA is not an optimal biomarker for disease severity and disability prediction among current smoker, ex-smoker or non-smoker pwMS.

Multiomic approach and Mendelian randomization analysis identify causal associations between blood biomarkers and subcortical brain structure volumes

Alterations in subcortical brain structure volumes have been found to be associated with several neurodegenerative and psychiatric disorders. At the same time, genome-wide association studies (GWAS) have identified numerous common variants associated with brain structure. In this study, we integrate these findings, aiming to identify proteins, metabolites, or microbes that have a putative causal association with subcortical brain structure volumes via a two-sample Mendelian randomization approach. This method uses genetic variants as instrument variables to identify potentially causal associations between an exposure and an outcome. The exposure data that we analyzed comprised genetic associations for 2,994 plasma proteins, 237 metabolites, and 103 microbial genera. The outcome data included GWAS data for seven subcortical brain structure volumes including accumbens, amygdala, caudate, hippocampus, pallidum, putamen, and thalamus. Eleven proteins and six metabolites were found to have a significant association with subcortical structure volumes. We found causal associations between amygdala volume and granzyme A as well as association between accumbens volume and plasma protease c1 inhibitor. Among metabolites, urate had the strongest association with thalamic volume. No significant associations were detected between the microbial genera and subcortical brain structure volumes. We also observed significant enrichment for biological processes such as proteolysis, regulation of the endoplasmic reticulum apoptotic signaling pathway, and negative regulation of DNA binding. Our findings provide insights to the mechanisms through which brain volumes may be affected in the pathogenesis of neurodevelopmental and psychiatric disorders and point to potential treatment targets for disorders that are associated with subcortical brain structure volumes.

Differences in the Association Between Alcoholic Beverage Type and Serum Urate Levels Using Standardized Ethanol Content

IMPORTANCE

Differences have been observed in the association of serum urate levels with consumption of different types of alcoholic beverages. However, previous studies have not standardized the unit of intake for ethanol content, and only limited types of alcoholic beverages have been evaluated.

OBJECTIVE

To examine differences in the association of serum urate levels with various types of alcoholic beverages when their intakes are standardized for ethanol content.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cross-sectional study was conducted using data from participants aged 20 years or older who completed a medical checkup at St Luke's International University in Japan between October 1, 2012, and October 31, 2021. Participant demographics, blood test results, and lifestyle questionnaire data were used as covariates. Analysis was performed in December 2021.

EXPOSURES

Consumption of alcoholic beverages, including beer, sake (rice wine), shochu (Japanese spirit), wine, and whiskey.

MAIN OUTCOMES AND MEASURES

Serum urate levels were measured during the medical checkup. The beverage unit was standardized to 1 standard drink, which contained 20 g of ethanol. Multivariable linear regression including interaction terms of alcohol consumption and dominant alcoholic beverage was performed.

RESULTS

This study included 78 153 participants. Their mean (SD) age was 47.6 (12.8) years; 36 463 (46.7%) were men and 41 690 were women (53.3%). A total of 45 755 participants (58.5%) were regular alcohol drinkers. Consistent associations of serum urate levels with alcohol consumption were observed in the beer-dominant group, with β coefficients (for 1 standard drink per day) of 0.14 mg/dL (95% CI, 0.11-0.17 mg/dL; P < .001) for men and 0.23 mg/dL (95% CI, 0.20-0.26 mg/dL; P < .001) for women. A moderate increase in serum urate levels was observed in the wine-dominant group compared with a modest and nonsignificant increase in the sake-dominant group, with β coefficients (for 1 standard drink per day) for the latter group of 0.05 mg/dL (95% CI, -0.01 to 0.10; P = .10) for men and 0.04 mg/dL (95% CI, -0.05 to 0.14 mg/dL; P = .38) for women. Restricted cubic splines showed different patterns in associations of serum urate levels with ethanol intake by dominant alcoholic beverages.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that the extent of the association of serum urate levels with alcohol intake was different for alcoholic beverages even after ethanol content was standardized. Higher beer consumption among men and women was consistently associated with higher serum urate levels, whereas sake was not associated with changes in serum urate levels. Therefore, alcoholic beverage type, in addition to ethanol content, should be considered as a factor contributing to hyperuricemia.

Screening method for the simultaneous determination of allantoin and uric acid from dried blood spots

Uric acid and its oxidation product allantoin are excellent biomarkers of oxidative stress in humans. Currently, there are high requirements not only for tests monitoring oxidative stress but also for screening laboratory tests in general. The highest demand is imposed on the simplest sampling, easy transport of the sample, and the shortest possible analysis time. The possible solution how to fulfil the requirements is sampling by dried blood spot technique with subsequent HPLC-MS/MS analysis. A fast, sensitive, and reliable HPLC-MS/MS method for the simultaneous determination of uric acid and allantoin from dried blood spots using stable isotopically labelled analogs as internal standards was developed. The separation took place in the reversed phase within 3 min, with protein precipitation and extraction in a one-step procedure. The analytical parameters of the method were satisfactory with an excellent linear range. The presented method was used to determine allantoin and uric acid levels in dried blood spot samples from 100 healthy volunteer donors. The median uric acid concentration in the cohort was 239.3 µmol/L and the median allantoin concentration was 5.6 µmol/L. The presented analytical protocol and method are suitable for screening and monitoring allantoin and uric acid levels as biomarkers of oxidative stress in clinical practice.

Oxidants and Antioxidants in the Redox Biochemistry of Human Red Blood Cells

Red blood cells (RBCs) are exposed to both external and internal sources of oxidants that challenge their integrity and compromise their physiological function and supply of oxygen to tissues. Autoxidation of oxyhemoglobin is the main source of endogenous RBC oxidant production, yielding superoxide radical and then hydrogen peroxide. In addition, potent oxidants from other blood cells and the surrounding endothelium can reach the RBCs. Abundant and efficient enzymatic systems and low molecular weight antioxidants prevent most of the damage to the RBCs and also position the RBCs as a sink of vascular oxidants that allow the body to maintain a healthy circulatory system. Among the antioxidant enzymes, the thiol-dependent peroxidase peroxiredoxin 2, highly abundant in RBCs, is essential to keep the redox balance. A great part of the RBC antioxidant activity is supported by an active glucose metabolism that provides reducing power in the form of NADPH via the pentose phosphate pathway. There are several RBC defects and situations that generate oxidative stress conditions where the defense mechanisms are overwhelmed, and these include glucose-6-phosphate dehydrogenase deficiencies (favism), hemoglobinopathies like sickle cell disease and thalassemia, as well as packed RBCs for transfusion that suffer from storage lesions. These oxidative stress-associated pathologies of the RBCs underline the relevance of redox balance in these anucleated cells that lack a mechanism of DNA-inducible antioxidant response and rely on a complex and robust network of antioxidant systems.

The initiator of neuroexcitotoxicity and ferroptosis in ischemic stroke: Glutamate accumulation

Glutamate plays an important role in excitotoxicity and ferroptosis. Excitotoxicity occurs through over-stimulation of glutamate receptors, specifically NMDAR, while in the non-receptor-mediated pathway, high glutamate concentrations reduce cystine uptake by inhibiting the System Xc-, leading to intracellular glutathione depletion and resulting in ROS accumulation, which contributes to increased lipid peroxidation, mitochondrial damage, and ultimately ferroptosis. Oxidative stress appears to crosstalk between excitotoxicity and ferroptosis, and it is essential to maintain glutamate homeostasis and inhibit oxidative stress responses in vivo. As researchers work to develop natural compounds to further investigate the complex mechanisms and regulatory functions of ferroptosis and excitotoxicity, new avenues will be available for the effective treatment of ischaemic stroke. Therefore, this paper provides a review of the molecular mechanisms and treatment of glutamate-mediated excitotoxicity and ferroptosis.

Effect of ApoE ε4 gene polymorphism on the correlation between serum uric acid and left ventricular hypertrophy remodeling in patients with coronary heart disease

Background

Hyperuricemia and dyslipidemia are associated with left ventricular hypertrophy (LVH), while the effect of ApoE gene polymorphism on the correlation between serum uric acid (UA) level and severity of LVH in patients with coronary heart disease (CHD) has not been clarified.

Methods

This was a retrospective observational study of patients with CHD. Patients were divided into groups of ε4 carriers and non-ε4 carriers based on sanger sequencing. The association of ApoE ε4 gene polymorphism, serum UA level, and LVH, determined by cardiac color Doppler ultrasound, was evaluated by multivariate analysis.

Results

A total of 989 CHD patients who underwent ApoE genotyping were enrolled and analyzed. Among them, the frequency of the ApoE ε4 genotype was 17.9% (15.7% for E3/4, 1.1% for E4/4, and 1.1% for E2/4). There were 159 patients with LVH, 262 with end-diastolic LV internal diameter (LVEDD) enlargement, 160 with left ventricular ejection fraction (LVEF) reduction, and 154 with heart failure. Multivariate analysis showed that for every increase of 10 μmol/L in serum UA level, the risk of LVH decreased in ε4 carriers (odds ratio (OR) = 0.94, 95% confidence interval (CI): 0.890-0.992, P = 0.025) and increased in non-ε4 carriers (OR = 1.03, 95% CI: 1.005-1.049, P = 0.016). The risk of LVEDD enlargement tended to decrease in ε4 carriers (OR = 0.98, 95% CI: 0.943-1.023, P = 0.391) and increased in non-ε4 carriers (OR = 1.03, 95% CI: 1.009-1.048, P = 0.003). The risk of LVEF reduction was reduced in ε4 carriers (OR = 0.996, 95% CI: 0.949-1.046, P = 0.872) and increased in non-ε4 carriers (OR = 1.02, 95% CI: 0.994-1.037, P = 0.17). The risk of LVEDD enlargement decreased in ε4 carriers (OR = 0.98, 95% CI: 0.931-1.036, P = 0.508) and increased in non-ε4 carriers (OR = 1.02, 95% CI: 0.998-1.042, P = 0.07).

Conclusion

High serum UA levels decreased the risk of LVH in ApoE ε4 carriers with CHD, while increased the risk of LVH in non-ε4 carriers.

Supplementation with uric and ascorbic acid protects stored red blood cells through enhancement of non-enzymatic antioxidant activity and metabolic rewiring

Redox imbalance and oxidative stress have emerged as generative causes of the structural and functional degradation of red blood cells (RBC) that happens during their hypothermic storage at blood banks. The aim of the present study was to examine whether the antioxidant enhancement of stored RBC units following uric (UA) and/or ascorbic acid (AA) supplementation can improve their storability as well as post-transfusion phenotypes and recovery by using in vitro and animal models, respectively. For this purpose, 34 leukoreduced CPD/SAGM RBC units were aseptically split in 4 satellite units each. UA, AA or their mixture were added in the three of them, while the fourth was used as control. Hemolysis as well as redox and metabolic parameters were studied in RBC units throughout storage. The addition of antioxidants maintained the quality parameters of stored RBCs, (e.g., hemolysis, calcium homeostasis) and furthermore, shielded them against oxidative defects by boosting extracellular and intracellular (e.g., reduced glutathione; GSH) antioxidant powers. Higher levels of GSH seemed to be obtained through distinct metabolic rewiring in the modified units: methionine-cysteine metabolism in UA samples and glutamine production in the other two groups. Oxidatively-induced hemolysis, reactive oxygen species accumulation and membrane lipid peroxidation were lower in all modifications compared to controls. Moreover, denatured/oxidized Hb binding to the membrane was minor, especially in the AA and mix treatments during middle storage. The treated RBC were able to cope against pro-oxidant triggers when found in a recipient mimicking environment in vitro, and retain control levels of 24h recovery in mice circulation. The currently presented study provides (a) a detailed picture of the effect of UA/AA administration upon stored RBCs and (b) insight into the differential metabolic rewiring when distinct antioxidant "enhancers" are used.

Identification of a plausible serum uric acid cut-off value as prognostic marker of stroke: the Uric Acid Right for Heart Health (URRAH) study

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting combined (fatal and non-fatal) cerebrovascular (CBV) events in the whole database. The URic acid Right for heArt Health study is a nationwide, multicenter, observational cohort study involving data on subjects aged 18-95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 120.7 ± 61.8 months. A total of 14,588 subjects were included in the analysis. A prognostic cut-off value of SUA able to discriminate combined CBV events (>4.79 mg/dL or >284.91 µmol/L) was identified by means of receiver operating characteristic curve in the whole database. Multivariate Cox regression analysis adjusted for confounders (age, sex, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, body mass index, low-density lipoprotein cholesterol, and use of diuretics) identified an independent association between SUA and combined CBV events in the whole database (HR 1.249, 95% confidence interval, 1.041-1.497, p = 0.016). The results of the present study confirm that SUA is an independent risk marker for CBV events after adjusting for potential confounding variables, including arterial hypertension, and demonstrate that >4.79 mg/dL is a valid prognostic cut-off value.

Epitaxial Self-Assembly of Interfaces of 2D Metal-Organic Frameworks for Electroanalytical Detection of Neurotransmitters

This paper identifies the electrochemical properties of individual facets of anisotropic layered conductive metal-organic frameworks (MOFs) based on M3(2,3,6,7,10,11-hexahydroxytriphenylene)2 (M3(HHTP)2) (M = Co, Ni). The electroanalytical advantages of each facet are then applied toward the electrochemical detection of neurochemicals. By employing epitaxially controlled deposition of M3(HHTP)2 MOFs on electrodes, the contribution of the basal plane ({001} facets) and edge sites ({100} facets) of these MOFs can be individually determined using electrochemical characterization techniques. Despite having a lower observed heterogeneous electron transfer rate constant, the {001} facets of the M3(HHTP)2 systems prove more selective and sensitive for the detection of dopamine than the {100} facets of the same MOF, with the limit of detection (LOD) of 9.9 ± 2 nM in phosphate-buffered saline and 214 ± 48 nM in a simulated cerebrospinal fluid. Langmuir isotherm studies accompanied by all-atom MD simulations suggested that the observed improvement in performance and selectivity is related to the adsorption characteristics of analytes on the basal plane versus edge sites of the MOF interfaces. This work establishes that the distinct crystallographic facets of 2D MOFs can be used to control the fundamental interactions between analyte and electrode, leading to tunable electrochemical properties by controlling their preferential orientation through self-assembly.

Oxidative Stress Markers and Sperm DNA Fragmentation in Men Recovered from COVID-19

SARS-CoV-2 negatively affects semen characteristics, impairs various biochemical processes in seminal fluid and within spermatogenic cells ultimately leading to male fertility decline. However, the distinct mechanisms, in particular, the role of oxidative stress on the consequences of coronavirus infection, have not been well investigated, which is the purpose of the present study. The standard semen parameters, its pro- and antioxidant system state, as well as the level of sperm DNA fragmentation, were assessed in 17 semen samples of men five months after the coronavirus infection and in 22 age-matched control patients. We determined that the DNA fragmentation rate negatively correlated with the period after coronavirus recovery, as well as seminal fluid superoxide dismutase activity and uric acid level. It was demonstrated that COVID-19 is not always associated with increased DNA fragmentation, allowing them to be considered as two independent factors. Thus, the most significant changes were noted in the samples of men after COVID-19 and abnormal TUNEL results: increased round cell number, decreased seminal fluid's nitrotyrosine level, and total antioxidant capacity and Zn, as well as an increased 8-hydroxy-2'-deoxyguanosine level within spermatozoa. The data obtained indicate that increased DNA fragmentation and diminished semen quality in men can be the result of an imbalance in semen pro- and antioxidant components after COVID-19.

Chemistry of Hydrogen Peroxide Formation and Elimination in Mammalian Cells, and Its Role in Various Pathologies

Hydrogen peroxide (H2O2) is a compound involved in some mammalian reactions and processes. It modulates and signals the redox metabolism of cells by acting as a messenger together with hydrogen sulfide (H2S) and the nitric oxide radical (•NO), activating specific oxidations that determine the metabolic response. The reaction triggered determines cell survival or apoptosis, depending on which downstream metabolic pathways are activated. There are several ways to produce H2O2 in cells, and cellular systems tightly control its concentration. At the cellular level, the accumulation of hydrogen peroxide can trigger inflammation and even apoptosis, and when its concentration in the blood reaches toxic levels, it can lead to bioenergetic failure. This review summarizes existing research from a chemical perspective on the role of H2O2 in various enzymatic pathways and how this biochemistry leads to physiological or pathological responses.

Uric Acid Reacts with Peroxidasin, Decreases Collagen IV Crosslink, Impairs Human Endothelial Cell Migration and Adhesion

Uric acid is considered the main substrate for peroxidases in plasma. The oxidation of uric acid by human peroxidases generates urate free radical and urate hydroperoxide, which might affect endothelial function and explain, at least in part, the harmful effects of uric acid on the vascular system. Peroxidasin (PXDN), the most recent heme-peroxidase described in humans, catalyzes the formation of hypobromous acid, which mediates collagen IV crosslinks in the extracellular matrix. This enzyme has gained increasing scientific interest since it is associated with cardiovascular disease, cancer, and renal fibrosis. The main objective here was to investigate whether uric acid would react with PXDN and compromise the function of the enzyme in human endothelial cells. Urate decreased Amplex Red oxidation and brominating activity in the extracellular matrix (ECM) from HEK293/PXDN overexpressing cells and in the secretome of HUVECs. Parallelly, urate was oxidized to 5-hydroxyisourate. It also decreased collagen IV crosslink in isolated ECM from PFHR9 cells. Urate, the PXDN inhibitor phloroglucinol, and the PXDN knockdown impaired migration and adhesion of HUVECs. These results demonstrated that uric acid can affect extracellular matrix formation by competing for PXDN. The oxidation of uric acid by PXDN is likely a relevant mechanism in the endothelial dysfunction related to this metabolite.

Association of Hyperuricemia with 10-Year Atherosclerotic Cardiovascular Disease Risk among Chinese Adults and Elders

The purpose of this cross-sectional study is to use a representative sample of the Chinese population and the atherosclerotic cardiovascular disease (ASCVD) risk assessment tool developed specifically for the Chinese to explore the prevalence of hyperuricemia (HUA) and the relationship between hyperuricemia and 10-year ASCVD risk in Chinese adults. Data was collected from the Chinese Physiological Constant and Health Condition survey. In this study, 12,988 subjects aged between 35 and 74 were selected by two-stage, cluster and random sampling. The sex-specific 10-year ASCVD risk scores equations, which were conducted by China-PAR project and specifically designed for Chinese adults, were used to assess the risk of developing ASCVD 10 years later. The ordinal regression model was used to explore the relationship between hyperuricemia and ASCVD risk. The total prevalence of hyperuricemia was 12.69%, and males’ prevalence was significantly higher than females (17.7% vs. 8.5%). Compared with people without hyperuricemia, the 10-year ASCVD risk scores of female with hyperuricemia increased significantly, but no significant increased happened in male. The ordinal regression model indicated that hyperuricemia subjects were 1.3 (males, 95% CI: 1.11–1.52) and 4.34 (females, 95% CI: 3.16–5.91) times more likely to increase their ASCVD risk levels than those without hyperuricemia. In conclusion, Hyperuricemia is prevalent among Chinese adults. In both genders, hyperuricemia was related with higher risk of 10-year ASCVD, and the relationship is much stronger in females than in males. Thus, sex-specific serum uric acid management and intervention strategies should be done in the prevention and control of cardiovascular events.

The Negative Association Between NAFLD Severity and CKD in a Non-Diabetic Gouty Population

Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) share common pathogenic mechanisms and risk factors. We aim to evaluate the association between NAFLD and CKD in a non-diabetic gouty population. The retrospective cross sectional study was performed on 1049 non-diabetic gouty participants, who were hospitalized between 2014 and 2020, across 4 districts in Shandong, China. Demographic and clinical characteristics of the study population were collected. The odds ratios (OR) and corresponding 95% confidence intervals (CI) about the NAFLD severity determined by ultrasonography were obtained by multiple logistic regression analysis. An unexpectedly inverse relationship was found between NAFLD severity and the risk of CKD in people with gout. Multivariate logistic regression analysis demonstrated that a higher degree of NAFLD severity is independently associated with a lower risk of CKD in people with gout, after adjusted for age, sex, smoking, gout duration, and metabolic risk factors including obesity, hypertension, hyperglycemia, hyperuricemia, and dyslipidemia, with OR 0.392 (95% CI 0.248-0.619, p<0.001), 0.379 (95% CI 0.233-0.616, p<0.001) and 0.148 (95% CI 0.043-0.512, p=0.003) in participants with mild, moderate, and severe NAFLD, respectively, compared to those without NAFLD. We also observed a weakened association of serum uric acid (SUA) with metabolic risk factors and NAFLD under circumstances of CKD in people with gout (r=-0.054, p=0.466). In conclusion, the presence and severity of NAFLD were negatively associated with the risk of CKD in the non-diabetic gouty population.

Contributions and Limitations of Mitochondria-Targeted and Non-Targeted Antioxidants in the Treatment of Parkinsonism: an Updated Review

As conventional therapeutics can only treat the symptoms of Parkinson's disease (PD), major focus of research in recent times is to slow down or prevent the progression of neuronal degeneration in PD. Non-targeted antioxidants have been an integral part of the conventional therapeutics regimen; however, their importance have lessened over time because of their controversial outcomes in clinical PD trials. Inability to permeate and localize within the mitochondria remains the main drawback on the part of non-targeted antioxidants inspite of possessing free radical scavenging properties. In contrast, mitochondrial-targeted antioxidants (MTAs), a special class of compounds have emerged having high advantages over non-targeted antioxidants by virtue of efficient pharmacokinetics and better absorption rate with capability to localize many fold inside the mitochondrial matrix. Preclinical experimentations indicate that MTAs have the potential to act as better alternatives compared to conventional non-targeted antioxidants in treating PD; however, sufficient clinical trials have not been conducted to investigate the efficacies of MTAs in treating PD. Controversial clinical outcomes on the part of non-targeted antioxidants and lack of clinical trials involving MTAs have made it difficult to go ahead with a direct comparison and in turn have slowed down the progress of development of safer and better alternate strategies in treating PD. This review provides an insight on the roles MTAs and non-targeted antioxidants have played in the treatment of PD till date in preclinical and clinical settings and discusses about the limitations of mitochondria-targeted and non-targeted antioxidants that can be resolved for developing effective strategies in treating Parkinsonism.

U-Shaped Association Between Serum Uric Acid and Hemorrhagic Transformation After Intravenous Thrombolysis

BACKGROUND

Uric acid (UA) has both antioxidative and pro-oxidative properties. The study aimed to investigate the relationship between serum UA and hemorrhagic transformation (HT) after intravenous thrombolysis in patients with acute ischemic stroke.

METHODS

The patients undergoing intravenous thrombolysis from two hospitals in China were retrospectively analyzed. HT was evaluated using computed tomography images reviewed within 24- 36h after thrombolysis. Symptomatic intracranial hemorrhage (sICH) was defined as HT accompanied by worsening neurological function. Multivariate logistic regression and spline regression models were performed to explore the relationship between serum UA levels and the risk of HT and sICH.

RESULTS

Among 503 included patients, 60 (11.9%) were diagnosed with HT and 22 (4.4%) developed sICH. Patients with HT had significant lower serum UA levels than those without HT (245 [214-325 vs. 312 [256-370] μmol/L, p < 0.001). Multivariable logistic regression analysis indicated that patients with higher serum UA levels had a lower risk of HT (OR per 10-μmol/L increase 0.96, 95%CI 0.92-0.99, p = 0.015). Furthermore, multiple-adjusted spline regression models showed a Ushaped association between serum UA levels and HT (p < 0.001 for non-linearity). Similar results were present between serum UA and sICH. Restricted cubic spline models predicted the lowest risk of HT and sICH when the serum UA levels were 386μmol/L.

CONCLUSION

The data show the U-shaped relationship between serum UA levels and the risk of HT and sICH after intravenous thrombolysis.

Antioxidant Responses Induced by Short-Term Activity–Estivation–Arousal Cycle in Pomacea canaliculata

Long-term estivation (45 days) in the apple snail Pomacea canaliculata induces an increase of non-enzymatic antioxidants, such as uric acid and reduced glutathione (GSH), which constitutes an alternative to the adaptive physiological strategy of preparation for oxidative stress (POS). Here, we studied markers of oxidative stress damage, uric acid levels, and non-enzymatic antioxidant capacity, enzymatic antioxidant defenses, such as superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), and transcription factors expression [forkhead box protein O (FOXO), hypoxia-inducible factor-1 alpha (HIF1α), and nuclear factor erythroid 2-related factor 2 (Nrf2)] in control active animals, 7-day estivating and aroused snails, in digestive gland, gill, and lung tissue samples. In the digestive gland, SOD and CAT activities significantly increased after estivation and decreased during arousal. Meanwhile, GST activity decreased significantly during the activity–estivation–arousal cycle. Gill CAT activity increased significantly at 7 days of estivation, and it decreased during arousal. In the lung, the CAT activity level increased significantly during the cycle. FOXO upregulation was observed in the studied tissues, decreasing its expression only in the gill of aroused animals during the cycle. HIF1α and Nrf2 transcription factors decreased their expression during estivation in the gill, while in the lung and the digestive gland, both transcription factors did not show significant changes. Our results showed that the short-term estivation induced oxidative stress in different tissues of P. canaliculata thereby increasing overall antioxidant enzymes activity and highlighting the role of FOXO regulation as a possible underlying mechanism of the POS strategy.

Effects of high serum uric acid levels on oxidative stress levels and semen parameters in male infertile patients

This study is to investigate the effect of high serum uric acid (UA) level on oxidative stress and semen quality of male infertility patients.A cohort of 654 male individuals aged between 20 and 45 years old were included in this study, and their semen and venous blood samples were collected. The serum UA, blood glucose, blood lipids, and hormone levels were determined by chemiluminescence method. The changes in inflammatory factors, oxidative stress, adipokines, and biochemical indices in seminal plasma were determined by ELISA. Organic acids in seminal plasma were detected with reversed-phase ultra high performance liquid chromatography.Compared with the control group, the amount of semen and the total number of sperm in the hyperuricemia group significantly reduced (P < .05). Semen volume decreased with the increase of serum UA level, and the total number of sperm also decreased. The level of luteinizing hormone increased and the level of testosterone decreased in the hyperuricemia group. The concentration of superoxide dismutase decreased and the concentration of endothelin increased in the hyperuricemia group (P < .05). The concentration of seminal plasma α-glucosidase and alkaline phosphatase in the hyperuricemia group decreased significantly (P < .05). Compared with the control group, the contents of ascorbic acid, tartaric acid, lactic acid, and UA in the seminal plasma were significantly reduced in the hyperuricemia group (P < .05).Blood UA level may become a new risk predictor of semen quality in infertile men.

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

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

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

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

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

The Influence of Serum Uric Acid on the Brain and Cognitive Dysfunction

Uric acid is commonly known for its bad reputation. However, it has been shown that uric acid may be actively involved in neurotoxicity and/or neuroprotection. These effects could be caused by oxidative stress or inflammatory processes localized in the central nervous system, but also by other somatic diseases or systemic conditions. Our interest was to summarize and link the current data on the possible role of uric acid in cognitive functioning. We also focused on the two putative molecular mechanisms related to the pathological effects of uric acid-oxidative stress and inflammatory processes. The hippocampus is a prominent anatomic localization included in expressing uric acid's potential impact on cognitive functioning. In neurodegenerative and mental disorders, uric acid could be involved in a variety of ways in etiopathogenesis and clinical presentation. Hyperuricemia is non-specifically observed more frequently in the general population and after various somatic illnesses. There is increasing evidence to support the hypothesis that hyperuricemia may be beneficial for cognitive functioning because of its antioxidant effects but may also be a potential risk factor for cognitive dysfunction, in part because of increased inflammatory activity. In this context, gender specificities must also be considered.