Role of urate, xanthine oxidase and the effects of allopurinol in vascular oxidative stress

Dairy Intake and Risk of Cardiovascular Disease

PURPOSE OF REVIEW

Due to inconsistent findings on dairy consumption and CVD and all-cause mortality, we performed a narrative literature review to the current literature on dairy and its association with CVD.

RECENT FINDINGS

Due to their complex biochemistry, dairy consumption is a rather heterogeneous exposure. Multiple pathways have been proposed from dairy consumption and CVD. Current guidelines advocate for consumption of low-fat dairy products particularly milk, cheese, and yogurt, although the evidence for this is scant. Randomized clinical trials and large prospective studies on lipid-related cardiometabolic disease risk factors are consistent with results from most meta-analyses of prospective cohort studies, which suggest null or inverse relationship between CVD risk and mortality with dairy consumption although there is no clear dose response relationship. Most of current evidence suggests that dairy products are neutral or positive effect on human cardiovascular diseases.

Oxidative stress and antioxidant capacity: development and prospects

Signaling pathways regulating redox reactions are activated to balance the redox status and maintain the normal function of cells.

Severe Hypouricemia Impairs Endothelium-Dependent Vasodilatation and Reduces Blood Pressure in Healthy Young Men: A Randomized, Placebo-Controlled, and Crossover Study

Background

Uric acid (UA) is a plasmatic antioxidant that has possible effects on blood pressure. The effects of UA on endothelial function are unclear. We hypothesize that endothelial function is not impaired unless significant UA depletion is achieved through selective xanthine oxidase inhibition with febuxostat and recombinant uricase (rasburicase).

Methods and Results

Microvascular hyperemia, induced by iontophoresis of acetylcholine and sodium nitroprusside, and heating‐induced local hyperemia after iontophoresis of saline and a specific nitric oxide synthase inhibitor were assessed by laser Doppler imaging. Blood pressure and renin‐angiotensin system markers were measured, and arterial stiffness was assessed. CRP (C‐reactive protein), allantoin, chlorotyrosine/tyrosine ratio, homocitrulline/lysine ratio, myeloperoxidase activity, malondialdehyde, and interleukin‐8 were used to characterize inflammation and oxidative stress. Seventeen young healthy men were enrolled in a randomized, double‐blind, placebo‐controlled, 3‐way crossover study. The 3 compared conditions were placebo, febuxostat alone, and febuxostat together with rasburicase. The allantoin (μmol/L)/UA (μmol/L) ratio differed between sessions (P<0.0001). During the febuxostat‐rasburicase session, heating‐induced hyperemia became altered in the presence of nitric oxide synthase inhibition; and systolic blood pressure, angiotensin II, and myeloperoxidase activity decreased (P≤0.03 versus febuxostat). The aldosterone concentration decreased in the febuxostat‐rasburicase group (P=0.01). Malondialdehyde increased when UA concentration decreased (both P<0.01 for febuxostat and febuxostat‐rasburicase versus placebo). Other parameters remained unchanged.

Conclusions

A large and short‐term decrease in UA in humans alters heat‐induced endothelium‐dependent microvascular vasodilation, slightly reduces systolic blood pressure through renin‐angiotensin system activity reduction, and markedly reduces myeloperoxidase activity when compared with moderate UA reduction. A moderate or severe hypouricemia leads to an increase in lipid peroxidation through loss of antioxidant capacity of plasma.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03395977.

Gender-specific associations between coronary heart disease and other chronic diseases: cross-sectional evaluation of national survey data from adult residents of Germany

Background

Combinations of coronary heart disease (CHD) and other chronic conditions complicate clinical management and increase healthcare costs. The aim of this study was to evaluate gender-specific relationships between CHD and other comorbidities.

Methods

We analyzed data from the German Health Interview and Examination Survey (DEGS1), a national survey of 8152 adults aged 18–79 years. Female and male participants with self-reported CHD were compared for 23 chronic medical conditions. Regression models were applied to determine potential associations between CHD and these 23 conditions.

Results

The prevalence of CHD was 9% (547 participants): 34% (185) were female CHD participants and 66% (362) male. In women, CHD was associated with hypertension (OR = 3.28 (1.81–5.9)), lipid disorders (OR = 2.40 (1.50–3.83)), diabetes mellitus (OR = 2.08 (1.24–3.50)), kidney disease (OR = 2.66 (1.101–6.99)), thyroid disease (OR = 1.81 (1.18–2.79)), gout/high uric acid levels (OR = 2.08 (1.22–3.56)) and osteoporosis (OR = 1.69 (1.01–2.84)). In men, CHD patients were more likely to have hypertension (OR = 2.80 (1.94–4.04)), diabetes mellitus (OR = 1.87 (1.29–2.71)), lipid disorder (OR = 1.82 (1.34–2.47)), and chronic kidney disease (OR = 3.28 (1.81–5.9)).

Conclusion

Our analysis revealed two sets of chronic conditions associated with CHD. The first set occurred in both women and men, and comprised known risk factors: hypertension, lipid disorders, kidney disease, and diabetes mellitus. The second set appeared unique to women: thyroid disease, osteoporosis, and gout/high uric acid. Identification of shared and unique gender-related associations between CHD and other conditions provides potential to tailor screening, preventive, and therapeutic options.

Garlic and allopurinol attenuate hepatic apoptosis induced by fipronil in male albino rats

Fipronil (FPN) can induce oxidative tissue damage and may be contemplated as an apoptosis inducer. Our aim is to investigate the possible hepatoprotective roles of garlic or allopurinol (ALP) against fipronil subacute toxicity. Thirty-six mature male albino rats were randomly divided into six groups; the first group was saved as control (C), the 2nd (G) was orally intubated with 500 mg/kg aqueous garlic extract, and the 3rd (A) received 150 mg/L allopurinol in their drinking water. The 4th group (F) was administered 13.277 mg/kg fipronil by gavage, while the 5th (G + F) and 6th (A + F) groups received the same doses of garlic and allopurinol, respectively two hours before fipronil intoxication. Our results revealed that FPN significantly increased the hepatic malondialdehyde, protein carbonyl levels, and the enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase, and xanthine oxidase, but it decreased glutathione-S-transferase compared to the control group. Moreover, FPN exhibited significant up-regulation in the hepatic pro-apoptotic (Bax) and caspase-3 genes expression, down-regulation in the anti-apoptotic (Bcl-2) mRNA gene expression and induced DNA fragmentation. Surprisingly, garlic or allopurinol co-treatment ameliorated the hepatic lipid peroxidation, antioxidants disruption, and apoptosis induced by FPN. In conclusion, garlic and allopurinol relieved the oxidative injury and reduced the fipronil-induced apoptosis probably by improving the tissue antioxidant defense system.

Creatinine, total cysteine and uric acid are associated with serum retinol in patients with cardiovascular disease

Purpose

We hypothesized that biomarkers and dietary factors related to cardiovascular disease risk were associated with serum retinol and evaluated these potential associations in patients with suspected coronary artery disease (CAD).

Methods

We used cross-sectional data from 4116 patients hospitalised for suspected CAD. Dietary data were obtained from a subgroup of 1962 patients using a food frequency questionnaire. Potential biomarkers and dietary factors were explored using linear regression modelling adjusted for age and sex. Regression coefficients and corresponding confidence intervals (CI) are given as  % change in serum retinol per unit change in the predictors. Analyses were performed in the total population and in strata of serum retinol tertiles.

Results

In age- and sex-adjusted models, serum creatinine (standardized β: 0.38, 95% CI [0.35, 0.42]), plasma total cysteine (0.26, [0.23, 0.29]), serum uric acid (0.30, [0.26, 0.33]) and plasma neopterin (0.22, [0.18, 0.25]) were positively associated, whereas plasma serine (− 0.15, [− 0.18, − 0.12]) and serum C-reactive protein (− 0.15, [− 0.18, − 0.12]) were inversely associated with serum retinol. When we included the significant biomarkers in a multivariate model, the model explained 33% of the variability (R² = 0.33) in serum retinol. The results were similar in the lower and upper tertiles of serum retinol. Weak or no associations were observed for dietary factors.

Conclusions

In patients with suspected CAD, concentrations of creatinine, cysteine and uric acid were positively associated with serum retinol. Future studies should assess whether retinol concentrations are influenced by metabolic alterations in patients at risk of cardiovascular disease.

Phosphoinositide-3 kinase gamma regulates caspase-1 activation and leukocyte recruitment in acute murine gout

This study investigates the participation of PI3Kγ in the development of joint inflammation and dysfunction in an experimental model of acute gout in mice. Acute gout was induced by injection of monosodium urate (MSU) crystals into the tibiofemoral joint of mice. The involvement of PI3Kγ was evaluated using a selective inhibitor and mice deficient for PI3Kγ (PI3Kγ^-/- ) or with loss of kinase activity. Neutrophils recovered from the inflamed joint were quantified and stained for phosphorylated Akt (pAkt) and production of reactive oxygen species (ROS). The adherence of leukocytes to the joint microvasculature was assessed by intravital microscopy and cleaved caspase-1 by Western blot. Injection of MSU crystals induced massive accumulation of neutrophils expressing phosphorylated Akt. In the absence of PI3Kγ, there was reduction of pAkt expression, chemokine production, and neutrophil recruitment. Genetic or pharmacological inhibition of PI3Kγ reduced the adherence of leukocytes to the joint microvasculature, even in joints with established inflammation. Neutrophils from PI3Kγ^-/- mice produced less ROS than wild-type neutrophils. There was decreased joint damage and dysfunction in the absence of PI3Kγ. In addition, in the absence of PI3Kγ activity, there was reduction of cleaved caspase-1 and IL-1β production in synovial tissue after injection of MSU crystals and leukotriene B₄ . Our studies suggest that PI3Kγ is crucial for MSU crystal-induced acute joint inflammation. It is necessary for regulating caspase-1 activation and for mediating neutrophil migration and activation. Drugs that impair PI3Kγ function may be useful to control acute gout inflammation.

Metabolomic signature of exposure and response to citalopram/escitalopram in depressed outpatients

Metabolomics provides valuable tools for the study of drug effects, unraveling the mechanism of action and variation in response due to treatment. In this study we used electrochemistry-based targeted metabolomics to gain insights into the mechanisms of action of escitalopram/citalopram focusing on a set of 31 metabolites from neurotransmitter-related pathways. Overall, 290 unipolar patients with major depressive disorder were profiled at baseline, after 4 and 8 weeks of drug treatment. The 17-item Hamilton Depression Rating Scale (HRSD17) scores gauged depressive symptom severity. More significant metabolic changes were found after 8 weeks than 4 weeks post baseline. Within the tryptophan pathway, we noted significant reductions in serotonin (5HT) and increases in indoles that are known to be influenced by human gut microbial cometabolism. 5HT, 5-hydroxyindoleacetate (5HIAA), and the ratio of 5HIAA/5HT showed significant correlations to temporal changes in HRSD17 scores. In the tyrosine pathway, changes were observed in the end products of the catecholamines, 3-methoxy-4-hydroxyphenylethyleneglycol and vinylmandelic acid. Furthermore, two phenolic acids, 4-hydroxyphenylacetic acid and 4-hydroxybenzoic acid, produced through noncanconical pathways, were increased with drug exposure. In the purine pathway, significant reductions in hypoxanthine and xanthine levels were observed. Examination of metabolite interactions through differential partial correlation networks revealed changes in guanosine-homogentisic acid and methionine-tyrosine interactions associated with HRSD17. Genetic association studies using the ratios of these interacting pairs of metabolites highlighted two genetic loci harboring genes previously linked to depression, neurotransmission, or neurodegeneration. Overall, exposure to escitalopram/citalopram results in shifts in metabolism through noncanonical pathways, which suggest possible roles for the gut microbiome, oxidative stress, and inflammation-related mechanisms.

The anti-hyperuricemic effect of four astilbin stereoisomers in Smilax glabra on hyperuricemic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Smilax glabra Roxb. (SG), a Chinese medicinal herb which called "tufuling", is believed to be effective in treating hyperuricemia and gout symptoms. But the active substance and pharmacological mechanism of reducing uric acid remain unknown. This study aimed to obtain the total flavonoids including four astilbin stereoisomers and to examine their effects on reducing uric acid content in hyperuricemic mice.

MATERIALS AND METHODS

The total flavonoids of S. glabra (TFSG) were purified and then analysed by HPLC-PDA-MS. The effect of TFSG on the content of serum uric acid (S_UA), Serum creatinine (S_Cr), blood urea nitrogen (BUN) and the activities of xanthine oxidase (XOD) in hyperuricemic mouse model induced by potassium oxonate were examined. Western blot and PCR method were also used to investigate whether TFSG have effect on renal transport protein organic anion transporter 1 (OAT1), organic cation/carnitine transporter 2 (OCTN2) and their mRNA in hypeuricemic mice.

RESULT

Total flavonoids were obtained from EtOAc soluble portion of S. glabra. Four compounds were identified as neoastilbin, astilbin, neoisoastilbin and isoastilbin, which accounted for 55.6% of total flavonoids. TFSG could significantly reduce the serum uric acid content in hyperuricemic mouse (p < 0.01 or p < 0.05). The activities of hepatic XOD have been reduced in hyperuricemic mouse administered with 125 mg/kg TFSG (p < 0.05). The expressions of renal OAT1, OCTN2 and their mRNA have been up-regulated in hyperuricemic mice administered with TFSG (250, 125 mg/kg) (p < 0.01or p < 0.05). TFSG (62.5 mg/kg) could also elevated the expression of renal OCTN2 (p < 0.05).

CONCLUSION

A novel and simple method for preparative separation of astilbin stereoisomers from S. glabra was developed. It was the first time to obtain total flavonoids (including four marker compounds) of S. glabra, and the total content was up to 55.6%. The results suggested TFSG has significant effect on reducing uric acid in hyperuricemic mice by inhibiting the XOD activities and up-regulating the expression of OAT1, OCTN2 and their mRNA in kidney tissue.

Urate-lowering therapy alleviates atherosclerosis inflammatory response factors and neointimal lesions in a mouse model of induced carotid atherosclerosis

Hyperuricemia (HU) is a cause of gout. Clinical studies show a link between HU and cardiovascular disease. However, the role of soluble serum urate (SU) on atherosclerosis development remains elusive. We aimed to use a new HU mouse model [Uricase/Uox knockout (KO)] to further investigate the relationship between HU and atherosclerosis. A mouse model by perivascular collar placement of induced carotid atherosclerosis was established in male Uox-KO mice. The Uox-KO mice had elevated SU levels and enhanced levels of atherosclerosis inflammatory response proteins. In contrast, Uox-KO mice with carotid atherosclerosis showed severe neointimal changes in histology staining consistent with increases in intimal area and increases in proliferating cell nuclear antigen (PCNA)- and F4/80-positive cells. Allopurinol reduced neointimal areas induced by the perivascular collar in hyperuricemic mice, accompanied by decreased expression of PCNA- and F4/80-positive cells. Urate-lowering treatment alleviated atherosclerosis inflammatory response factors and reactive oxygen species (ROS) intensities in both collar placement Uox-KO mice and urate-stimulated human umbilical vein endothelial cells (HUVECs). In vitro results using HUVECs showed ROS was induced by urate and ROS induction was abrogated using antioxidants. These data demonstrate that urate per se does not trigger atherosclerosis intima lesions in male mice. Urate worsens carotid neointimal lesions induced by the perivascular collar and urate-lowering therapy partially abrogates the effects. The current study warrants clinical studies on the possible benefits of urate-lowering therapy in atherosclerosis patients with HU.

Adenine acts in the kidney as a signaling factor and causes salt- and water-losing nephropathy: early mechanism of adenine-induced renal injury

Chronic adenine feeding is extensively used to develop animal models of chronic renal failure with metabolic features resembling those observed in humans. However, the mechanism by which adenine induces renal failure is poorly understood. In this study, we examined the early effects of adenine on water metabolism and salt balance in rats placed in metabolic cages and fed control or adenine-containing diets for 7 days. Molecular and functional studies demonstrated that adenine-fed rats exhibited a significant reduction in food intake, polyuria, polydipsia, decreased urine osmolality, and increased salt wasting. These effects are independent of changes in food intake and result from a coordinated downregulation of water channel aquaporin-2 (AQP2) and salt transporter (Na⁺-K⁺-Cl^- cotransporter 2; NKCC2) in the collecting duct and medullary thick ascending limb, respectively. As a result, adenine-fed rats exhibited massive volume depletion, as indicated by a significant body weight loss, increased blood urea nitrogen, and increased hematocrit and hemoglobin levels, all of which were significantly corrected with NaCl replacement. Adenine-induced urinary concentrating defect was not corrected by exogenous arginine vasopressin (AVP), and it correlated with reduced cAMP production in vivo and in vitro. In conclusion, adenine acts on renal tubules as a signaling molecule and causes nephrogenic diabetes insipidus with salt wasting, at least, by directly interfering with AVP V2 receptor signaling with subsequent downregulation of NKCC2 and AQP2 in the kidney. The combination of renal fluid loss and decreased food intake with subsequent massive volume depletion likely plays an important role in the development of early prerenal failure that progresses to chronic kidney disease in long-term adenine feeding.

Gout - An update of aetiology, genetics, co-morbidities and management

Gout is an increasingly common chronic disorder of urate crystal deposition that manifests as flares of acute inflammatory arthritis. Hyperuricaemia is a prerequisite and a fifth of both men and woman are hyperuricaemic. The prevalence of gout is much lower than the prevalence of hyperuricaemia for reasons that are not currently clear. Gout is more common in men than women prior to menopause due to the uricosuric effects of oestrogen, but after menopause the incidence of gout rises substantially in women. Co-morbidities are an important issue in gout, with cardiovascular disease, diabetes mellitus, obesity and chronic kidney disease all common in patients with gout. Environmental factors like diet affect the incidence of gout but there is little evidence to support an emphasis on diet in treating established gout. The diagnosis of gout is often made without the use of joint aspiration and validated diagnostic rules are available for both primary and secondary care as well as classification criteria for research use. The overarching principle of the management of gout with pharmacotherapy is the need to reduce serum urate levels to below a target of 0.30 mmol/L or 0.36 mmol/L depending on whether it is tophaceous or non-tophaceous respectively. The use of allopurinol has been researched extensively and newer strategies for safer effective dosing are now recommended. Newer agents have been introduced for the treatment of gout, including febuxostat and lesinurad. A number of important questions in the field are under current investigation.

Relation of Elevated Serum Uric Acid Level to Endothelial Dysfunction in Patients with Acute Coronary Syndrome

Aim: Serum uric acid (SUA) level is known to have a prognostic value in patients with acute coronary syndrome (ACS). Endothelial function plays an important role in the development of cardiovascular disease. Although relation between SUA level and endothelial function has been previously studied in various populations, it is partially understood in patients with ACS.

Methods: A total of 55 patients with ACS with measurements of SUA level and reactive hyperemia index (RHI) to evaluate endothelial function were included. They were classified into three groups according to the tertiles of SUA level. The tertiles of SUA level were as follows: low tertile, ≤ 5.2 mg/dl; intermediate tertile, 5.3 to 6.5 mg/dl; and high tertile, ≥ 6.6 mg/dl.

Results: Mean SUA level and RHI were 5.8 ± 1.5 mg/dl and 1.88 ± 0.58. There was a significant negative correlation between SUA level and RHI (r = −0.41, p = 0.002). RHI was stepwisely observed in favor of the higher tertile groups (2.14 ± 0.74 vs. 1.84 ± 0.45 vs. 1.67 ± 0.38, p = 0.04). Multivariate analysis showed elevated SUA level as an independent predictor of reduced RHI.

Conclusion: Elevated SUA level was significantly associated with endothelial dysfunction in patients with ACS, possibly leading to subsequent poor outcomes following ACS.

Gout and the risk of age-related macular degeneration in the elderly

Objective

To assess whether gout is associated with incident age-related macular degeneration (AMD)

Methods

We used the 5% Medicare claims data from 2006–12 for all beneficiaries who were enrolled in Medicare fee-for-service (Parts A, B) and not enrolled in a Medicare Advantage Plan, and resided in the U.S. People were censored at the occurrence of new diagnosis of AMD, death or the end of study (12/31/2012), whichever occurred first. We used multivariable-adjusted Cox regression analyses to assess the association of gout with incident AMD, adjusted for demographics, comorbidity, and use of medications for cardiovascular disease and gout. Hazard ratios and 95% confidence intervals were calculated.

Results

In this observational cohort study, of the 1,684,314 eligible people, 116,097 developed incident AMD (6.9%). Incidence rates of AMD per 1,000 person-years were 20.1 for people with gout and 11.7 for people without gout. In multivariable-adjusted analyses, a diagnosis of gout was significantly associated with a higher risk of incident AMD with a hazard ratio of 1.39 (95% CI, 1.35, 1.43). This association was confirmed in sensitivity analyses that substituted Charlson-Romano comorbidity index continuous score with either a categorical Charlson-Romano comorbidity index score or individual Charlson-Romano index comorbidities plus hypertension, hyperlipidemia and coronary artery disease. Other covariates significantly associated with higher hazards of incident AMD were older age, female gender, White race/ethnicity, and higher Charlson-Romano comorbidity index score.

Conclusions

We noted a novel association of gout with AMD in the elderly. Future studies should investigate the pathways that mediate this association.

Increased plasma xanthine oxidoreductase activity deteriorates coronary artery spasm

Increased reactive oxygen species (ROS) contributes to the development of endothelial dysfunction, which is involved in coronary artery spasm (CAS). Xanthine oxidoreductase (XOR) plays a pivotal role in producing both uric acid and ROS. However, the association between plasma XOR activity and CAS has not been elucidated. The aim of this study was to investigate whether plasma XOR activity is associated with CAS. We measured XOR activity in 104 patients suspected for CAS, who presented without significant coronary artery stenosis and underwent intracoronary acetylcholine provocation tests. CAS was provoked in 44 patients and they had significantly higher XOR activity as compared with those without CAS. The patients were divided into three groups based on the XOR activity. The prevalence rate of CAS was increased with increasing XOR activity. A multivariate logistic regression analysis showed that the 3rd tertile group exhibited a higher incidence of CAS as compared with the 1st tertile group [odds ratio (OR) 6.9, P = 0.001) and the 2nd tertile group (OR 3.2, P = 0.033) after adjustment for conventional CAS risk factors, respectively. The C index was significantly improved by the addition of XOR activity to the baseline model based on CAS risk factors. Furthermore, the 3rd tertile group had the highest incidence of severe spasm defined as total obstruction, flow-limiting stenosis, diffuse spasm, multivessel spasm, and/or lethal arrhythmia. This is a first report to elucidate the association of plasma XOR activity with CAS. Increased plasma XOR activity is significantly associated with CAS.

Association between allopurinol use and Parkinson's disease in older adults

INTRODUCTION

Little evidence is available about the association between allopurinol use and Parkinson's disease. The present study aimed to explore the association between allopurinol use and Parkinson's disease in older adults in Taiwan.

METHODS

We conducted a population-based case-control study using the database of the Taiwan National Health Insurance Program. In total, 4399 subjects aged ≥ 65 years with newly diagnosed Parkinson's disease between 2000 and 2013 were included as the cases. Additionally, 4399 subjects aged ≥ 65 years without Parkinson's disease were randomly selected as the controls. Both cases and controls were matched for age and comorbidities. Ever use of allopurinol was defined as subjects who had at least a prescription for allopurinol before the index date, whereas never use of allopurinol was defined as those who never had a prescription for allopurinol before the index date. We used the logistic regression model to calculate the odds ratio (OR) and 95% confidence interval (CI) for the association between allopurinol use and Parkinson's disease.

RESULTS

The OR of Parkinson's disease was 0.93 for subjects with ever use of allopurinol (95% CI 0.82, 1.04), compared with never use.

CONCLUSIONS

No association can be detected between allopurinol use and Parkinson's disease in older adults in Taiwan.

Vascular endothelium dysfunction: a conservative target in metabolic disorders

AIM

Vascular endothelium plays a role in capillary transport of nutrients and drugs and regulates angiogenesis, homeostasis, as well as vascular tone and permeability as a major regulator of local vascular homeostasis. The present study has been designed to investigate the role of endothelium in metabolic disorders.

METHODS

The endothelium maintains the balance between vasodilatation and vasoconstriction, procoagulant and anticoagulant, prothrombotic and antithrombotic mechanisms.

RESULTS

Diabetes mellitus causes the activation of aldose reductase, polyol pathway and advanced glycation-end-product formation that collectively affect the phosphorylation status and expression of endothelial nitric oxide synthatase (eNOS) and causes vascular endothelium dysfunction. Elevated homocysteine levels have been associated with increase in LDL oxidation, generation of hydrogen peroxides, superoxide anions that increased oxidative degradation of nitric oxide. Hyperhomocysteinemia has been reported to increase the endogenous competitive inhibitors of eNOS viz L-N-monomethyl arginine (L-NMMA) and asymmetric dimethyl arginine (ADMA) that may contribute to vascular endothelial dysfunction. Hypercholesterolemia stimulates oxidation of LDL cholesterol, release of endothelins, and generation of ROS. The increased cholesterol and triglyceride level and decreased protective HDL level, decreases the activity and expression of eNOS and disrupts the integrity of vascular endothelium, due to oxidative stress. Hypertension also stimulates release of endothelins, vasoconstrictor prostanoids, angiotensin II, inflammatory cytokines, xanthine oxidase and, thereby, reduces bioavailability of nitric oxide.

CONCLUSION

Thus, the cellular and molecular mechanisms underlying diabetes mellitus, hyperhomocysteinemia, hypercholesterolemia hypertension and hyperuricemia leads to an imbalance of phosphorylation and dephosphorylation status of lipid and protein kinase that cause modulation of vascular endothelial L-arginine/nitric oxide synthetase (eNOS), to produce vascular endothelium dysfunction.

Baseline and changes in serum uric acid independently predict glucose control among community-dwelling women

BACKGROUND

Elevated serum uric acid (SUA) levels are associated with glucose control. However, whether baseline and changes in SUA predict long-term follow-up glucose control [e.g., glycated hemoglobin (HbA1c)] remains unclear.

METHODS

The subjects comprised 393 women aged 71 ± 8 years and 279 men aged 71 ± 10 years from a rural village. We have identified participants who underwent a similar examination 11 years prior, and subjects were divided into four groups based on the tertiles of baseline and changes in SUA, and examined the relationship between baseline and changes in SUA, and glucose control evaluated by follow-up HbA1c after 11-years.

RESULTS

In both genders, follow-up SUA were significantly higher in Group 4 (i.e., women: Group 4, baseline SUA ≥ 4.0 mg/dL and changes in SUA ≥ 0.8 mg/dL; men: Group 4, ≥ 5.3 mg/dL and ≥ 0.4 mg/dL) than in the other Groups, but eGFR was significantly lower. Only in women, there were significant differences among the four groups regarding follow-up HbA1c, and follow-up HbA1c was highest in Group 4. In addition, the interaction between baseline and changes in SUA (F = 5.391, p = 0.021) as well as baseline low-density lipoprotein cholesterol (LDL-C) (F = 13.793, p < 0.001), estimated glomerular filtration ratio (F = 10.715, p = 0.001), HbA1c (F = 118.285, p < 0.001), SUA (F = 9.457, p = 0.002), and changes in SUA (F = 7.757, p = 0.006) was a significant and independent determinant of follow-up HbA1c. Multivariate-adjusted follow-up HbA1c (p = 0.002) were significantly higher in Group 4 than the other groups.

CONCLUSIONS

These results suggested that combined assessment of baseline and changes in SUA provides increased information for long-term predictive glucose control, independent of other confounding factors in community-dwelling women.

Serum uric acid levels and multiple health outcomes: umbrella review of evidence from observational studies, randomised controlled trials, and Mendelian randomisation studies

Objective To map the diverse health outcomes associated with serum uric acid (SUA) levels.Design Umbrella review.Data sources Medline, Embase, Cochrane Database of Systematic Reviews, and screening of citations and references.Eligibility criteria Systematic reviews and meta-analyses of observational studies that examined associations between SUA level and health outcomes, meta-analyses of randomised controlled trials that investigated health outcomes related to SUA lowering treatment, and Mendelian randomisation studies that explored the causal associations of SUA level with health outcomes.Results 57 articles reporting 15 systematic reviews and144 meta-analyses of observational studies (76 unique outcomes), 8 articles reporting 31 meta-analyses of randomised controlled trials (20 unique outcomes), and 36 articles reporting 107 Mendelian randomisation studies (56 unique outcomes) met the eligibility criteria. Across all three study types, 136 unique health outcomes were reported. 16 unique outcomes in meta-analyses of observational studies had P<10-6, 8 unique outcomes in meta-analyses of randomised controlled trials had P<0.001, and 4 unique outcomes in Mendelian randomisation studies had P<0.01. Large between study heterogeneity was common (80% and 45% in meta-analyses of observational studies and of randomised controlled trials, respectively). 42 (55%) meta-analyses of observational studies and 7 (35%) meta-analyses of randomised controlled trials showed evidence of small study effects or excess significance bias. No associations from meta-analyses of observational studies were classified as convincing; five associations were classified as highly suggestive (increased risk of heart failure, hypertension, impaired fasting glucose or diabetes, chronic kidney disease, coronary heart disease mortality with high SUA levels). Only one outcome from randomised controlled trials (decreased risk of nephrolithiasis recurrence with SUA lowering treatment) had P<0.001, a 95% prediction interval excluding the null, and no large heterogeneity or bias. Only one outcome from Mendelian randomisation studies (increased risk of gout with high SUA levels) presented convincing evidence. Hypertension and chronic kidney disease showed concordant evidence in meta-analyses of observational studies, and in some (but not all) meta-analyses of randomised controlled trials with respective intermediate or surrogate outcomes, but they were not statistically significant in Mendelian randomisation studies.Conclusion Despite a few hundred systematic reviews, meta-analyses, and Mendelian randomisation studies exploring 136 unique health outcomes, convincing evidence of a clear role of SUA level only exists for gout and nephrolithiasis.

Safety and effect of high dose allopurinol in patients with severe left ventricular systolic dysfunction

Introduction: Allopurinol used in the treatment of gout has been shown to improve the vascular endothelial dysfunction and reduce the dysfunction of the failing heart. This study was done to evaluate the effect and safety of allopurinol in non-hyperuricemic patients with chronic severe left ventricular (LV) dysfunction.

Methods: In this study, 35 consecutive cases of non-hyperuricemic patients with chronic heart failure who had severe LV systolic dysfunction (ejection fraction of less than 35%) and were on optimal guideline directed medical therapies for at least 3 months were included. Allopurinol was administered with the dose of 300 mg po daily for 1 week and then it was up-titrated to a dose of 600 mg po daily for 3 months. Six minute walk test, strain imaging, laboratory testing were done for every patient at baseline and after 3 months treatment with allopurinol.

Results: In this study 30 heart failure (HF) patients with a mean age of 49.3 ± 14.4 years old were evaluated. No adverse effects were reported except for one case of skin rash after 4 days treatment which was excluded from the study. Study showed significant improvement of six minute walk test of the patients from 384.5 ± 81.5 meters to 402.8 ± 89.6 meters and the global longitudinal peak strain (P < 0.001). There was also significant decrease in the level of erythrocyte sedimentation rate and N-terminal pro-brain natriuretic peptide (NT-proBNP) after 3 months.

Conclusion: Allopurinol could be of benefit in non-hyperuricemic patients with severe LV systolic dysfunction without significant adverse effects. Randomized clinical trials are needed in future to confirm the results.

Critical revision of the medical treatment of gout in Brazil

Gout is considered the most common form of inflammatory arthritis in men over 40 years. The authors present a brief review of the current treatment of gout and discuss the existing pharmacological limitations in Brazil for the treatment of this disease. Although allopurinol is still the main drug administered for decreasing serum levels of uric acid in gout patients in this country, the authors also present data that show a great opportunity for the Brazilian drug market for the treatment of hyperuricemia and gout and especially for patients using private and public (SUS) health care systems.

Association between bisphosphonate therapy and outcomes from rehabilitation in older people

BACKGROUND

Bisphosphonate therapy may have actions beyond bone, including effects on cardiovascular, immune and muscle function. We tested whether bisphosphonate treatment is associated with improved outcomes in older people undergoing inpatient rehabilitation.

METHODS

Analysis of prospectively collected, linked routine clinical datasets. Participants were divided into never users of bisphosphonates, use prior to rehabilitation only, use after rehabilitation only, and current users (use before and after rehabilitation). We calculated change in 20-point Barthel scores during rehabilitation, adjusting for comorbid disease and laboratory data using multivariable regression analysis. Cox regression analyses were performed to analyse the association between bisphosphonate use and time to death or hospitalisation.

RESULTS

2797 patients were included in the analysis. Current bisphosphonate users showed greater improvement in Barthel score during rehabilitation than non-users (5.0 points [95%CI 4.3-5.7] vs 3.8 [95%CI 3.6-3.9]), but no difference compared to those receiving bisphosphonates only after discharge (5.1 [95%CI 4.6-5.5]). Previous bisphosphonate use was significantly associated with time to death (adjusted hazard ratio 1.41 [95%CI 1.15-1.73]) but less strongly with time to combined endpoint of hospitalisation or death (adjusted hazard ratio 1.18 [95%CI 0.98-1.48]). Use after discharge from rehabilitation was associated with reduced risk of death (adjusted hazard ratio 0.64 [95%CI 0.55-0.73]; hazard ratio per year of bisphosphonate prescription 0.98 [95%CI 0.97-0.99]).

CONCLUSION

Bisphosphonate use is unlikely to be causally associated with improved physical function in older people, but continuing use may be associated with lower risk of death.

New insight into mitochondrial changes in vascular endothelial cells irradiated by gamma ray

PURPOSE

To investigate alterations of mitochondria in irradiated endothelial cells to further elucidate the mechanism underlying radiation-induced heart disease.

MATERIALS AND METHODS

Experiments were performed using human umbilical vein endothelial cells (HUVECs). HUVECs were irradiated with single gamma ray dose of 0, 5, 10 and 20 Gy, respectively. Apoptosis was assessed by flow cytometry at 24, 48 and 72 h post-irradiation, respectively. The intracellular reactive oxygen species (ROS) was measured with 2',7'-dichlorofluorescein-diacetate (DCFH-DA) at 24 h post-irradiation. Mitochondrial membrane potential (ΔΨm) by JC-1 and the opening of mitochondrial permeability transition pore (mPTP) by a calcein-cobalt quenching method were detected at 24 h post-irradiation in order to measure changes of mitochondria induced by gamma ray irradiation.

RESULTS

Gamma ray irradiation increased HUVECs apoptosis in a dose-dependent and time-dependent manner. Irradiation also promoted ROS production in HUVECs in a dose-dependent manner. At 24 h post-irradiation, the results showed that irradiation decreases ΔΨm, however, paradoxically, flow cytometry showed green fluorescence instensity higher in irradiated HUVECs than in control HUVECs in an irradiation dose-dependent manner which indicated gamma ray irradiation inhibited mPTP opening in HUVECs.

CONCLUSIONS

Gamma ray irradiation induces apoptosis and ROS production of endothelial cells, and decreases ΔΨm meanwhile contradictorily inhibiting the opening of mPTP.

Lower serum uric acid level strongly predict short-term poor functional outcome in acute stroke with normoglycaemia: a cohort study in China

BACKGROUND

Conflicting results on the correlation between hyperuricemia and the prognosis of stroke had been reported and the close association between serum uric acid (SUA) and abnormal glycomatabolism might further complicate the assessment of the correlation. We aimed to investigate SUA in predicting the prognosis of acute stroke in different glycometabolism status.

METHODS

A total of 2907 patients aged from 18 to 85 (1220 diabetes mellitus (DM), 777 prediabetes and 910 normoglycemia) were selected from the Abnormal Glucose Regulation in Patients with Acute Stroke across China (ACROSS-China) study. The patients were divided into groups according to the SUA quartile as well as decile. The correlations between SUA and the poor outcome (mRS > 2) at discharge were assessed stratified by glucose metabolism status. Multivariate logistic regression was used to analyze the potential risk factors of poor in-hospital outcome of stroke and the risk-adjustment of the correlation between SUA and the prognosis of stroke. P < 0.05 was considered statistically significant.

RESULTS

SUA were divided first as Quartile1 to 4 (Quartile1 < 221 μmol L-1; Quartile2 (221-286) μmol L-1; Quartile3 (286-352) μmol L-1 and Quartile4 > 352 μmol L-1), then as decile1 to 10. In normoglycaemia, SUA quartiles, deciles and continuous SUA concentration were independently significantly associated with poor outcome. Q1 was independently associated with the higher possibility of poor functional outcome (compared to Q4, odds ratios (ORs) with 95% confidential interval (CI) was 3.79 (1.23-8.67) in Q1); Lower level of SUA in DM was also associated with poor functional outcome at discharge compared to the highest level of SUA(Q4)(OR with 95% CI, 2.07 (1.05-4.08)), however, lower SUA level was also related to severer stroke at admission in DM as well as in prediabetes (P < 0.001 in DM and 0.023 in prediabetes) and severer stroke resulted in worse functional outcome at discharge (OR with 95% CI, 12.15 (8.08-18.21) in DM and 11.58 (7.50-23.25) in prediabetes). But in normoglycamic stroke, SUA levels did not differ in stroke severity at admission (P = 0.066).

CONCLUSIONS

Low SUA level (<221 μmol L-1) independently and strongly predicts the short-term poor functional outcome in acute stroke with normoglycaemia other than diabetes or prediabetes.

Reactive oxygen species and antioxidant defense in human gastrointestinal diseases

Crohn's disease and ulcerative colitis, known together as inflammatory bowel diseases (IBDs), and celiac disease are the most common disorders affecting not only adults but also children. Both IBDs and celiac disease are associated with oxidative stress, which may play a significant role in their etiologies. Reactive oxygen species (ROS) such as superoxide radicals (O2•-), hydroxyl radicals (•OH), hydrogen peroxide (H2O2), and singlet oxygen (1O2) are responsible for cell death via oxidation of DNA, proteins, lipids, and almost any other cellular constituent. To protect biological systems from free radical toxicity, several cellular antioxidant defense mechanisms exist to regulate the production of ROS, including enzymatic and nonenzymatic pathways. Superoxide dismutase catalyzes the dismutation of O2•- to H2O2 and oxygen. The glutathione redox cycle involves two enzymes: glutathione peroxidase, which uses glutathione to reduce organic peroxides and H2O2; and glutathione reductase, which reduces the oxidized form of glutathione with concomitant oxidation of nicotinamide adenine dinucleotide phosphate. In addition to this cycle, GSH can react directly with free radicals. Studies into the effects of free radicals and antioxidant status in patients with IBDs and celiac disease are scarce, especially in pediatric patients. It is therefore very necessary to conduct additional research studies to confirm previous data about ROS status and antioxidant activities in patients with IBDs and celiac disease, especially in children.

Allopurinol attenuates rhabdomyolysis-associated acute kidney injury: Renal and muscular protection

BACKGROUND

Acute kidney injury (AKI) is the most severe complication of rhabdomyolysis. Allopurinol (Allo), a xanthine oxidase inhibitor, has been in the spotlight in the last decade due to new therapeutic applications related to its potent antioxidant effect. The aim of this study was to evaluate the efficacy of Allo in the prevention and treatment of rhabdomyolysis-associated AKI.

METHODS

Male Wistar rats were divided into five groups: saline control group; prophylactic Allo (300mg/L of drinking water, 7 days); glycerol (50%, 5ml/kg, IM); prophylactic Allo + glycerol; and therapeutic Allo (50mg/Kg, IV, 30min after glycerol injection) + glycerol.

RESULTS

Glycerol-injected rats showed markedly reduced glomerular filtration rate associated with renal vasoconstriction, renal tubular damage, increased oxidative stress, apoptosis and inflammation. Allo ameliorated all these alterations. We found 8-isoprostane-PGF_2a (F2-IsoP) as a main factor involved in the oxidative stress-mediated renal vasoconstriction following rhabdomyolysis. Allo reduced F2-IsoP renal expression and restored renal blood flow. Allo also reduced oxidative stress in the damaged muscle, attenuated muscle lesion/inflammation and accelerated muscular recovery. Moreover, we showed new insights into the pathogenesis of rhabdomyolysis-associated AKI, whereas Allo treatment reduced renal inflammation by decreasing renal tissue uric acid levels and consequently inhibiting the inflammasome cascade.

CONCLUSIONS

Allo treatment attenuates renal dysfunction in a model of rhabdomyolysis-associated AKI by reducing oxidative stress (systemic, renal and muscular), apoptosis and inflammation. This may represent a new therapeutic approach for rhabdomyolysis-associated AKI - a new use for an old and widely available medication.

Uric Acid as a Marker of Mortality and Morbidity in Fabry Disease

BACKGROUND

Serum uric acid (UA) elevation is common in patients with cardiovascular, renal and metabolic diseases. However, no study to date has analysed the role of UA in Fabry disease (FD).

OBJECTIVES

To evaluate the association between serum UA levels and mortality and morbidity in FD.

MATERIALS AND METHODS

We conducted a post-hoc analysis of a prospectively followed-up cohort of 124 patients with genetically proven FD. Serum UA levels were acquired at baseline; clinical events and mortality were assessed during regular visits every 6 to 12 months. The primary endpoint was a composite of multiple secondary outcomes: all-cause mortality, adverse cardiovascular events, progression of renal dysfunction and stroke or transient ischaemic attack (TIA). Predictive value was assessed using the Cox proportional hazards model and the Kaplan Meyer estimator.

RESULTS

During follow-up of 7.4 ± 3.7 years, 64 (52%) patients reached the primary combined endpoint. Overall, UA levels were significantly associated with combined outcome (p < 0.001) and remained independently associated after correcting for age, sex and estimated glomerular filtration rate (hazard ratio [HR] per 20 μmol/l increase 1.09, 95% confidence interval [95%CI] (1.00-1.19), p = 0.04). UA was associated with overall mortality in univariate analysis (p = 0.021); however, the association did not reach statistical significance after multivariate correction (HR per 20 μmol/l increase 1.07 95%CI 0.93-1.25, p = 0.32). Higher UA levels were also associated with cardiac adverse outcomes, progression of left ventricular hypertrophy and progression of renal dysfunction (ps < 0.001). No association was observed between UA levels and stroke or TIA (p = 0.323).

CONCLUSION AND IMPLICATIONS

Increased serum UA levels may represent an independent risk factor for adverse clinical outcomes in Fabry patients and are associated with all-cause mortality. UA is a widely available and cheap biomarker that may improve risk stratification of Fabry patients in clinical practice.

Dairy fat and risk of cardiovascular disease in 3 cohorts of US adults

BACKGROUND

Few prospective studies have examined dairy fat in relation to cardiovascular disease (CVD).

OBJECTIVE

We aimed to evaluate the association between dairy fat and incident CVD in US adults.

DESIGN

We followed 43,652 men in the Health Professionals Follow-Up Study (1986-2010), 87,907 women in the Nurses' Health Study (1980-2012), and 90,675 women in the Nurses' Health Study II (1991-2011). Dairy fat and other fat intakes were assessed every 4 y with the use of validated food-frequency questionnaires.

RESULTS

During 5,158,337 person-years of follow-up, we documented 14,815 incident CVD cases including 8974 coronary heart disease cases (nonfatal myocardial infarction or fatal coronary disease) and 5841 stroke cases. In multivariate analyses, compared with an equivalent amount of energy from carbohydrates (excluding fruit and vegetables), dairy fat intake was not significantly related to risk of total CVD (for a 5% increase in energy from dairy fat, the RR was 1.02; 95% CI: 0.98, 1.05), coronary heart disease (RR: 1.03; 95% CI: 0.98, 1.09), or stroke (RR: 0.99; 95% CI: 0.93, 1.05) (P > 0.05 for all). In models in which we estimated the effects of exchanging different fat sources, the replacement of 5% of energy intake from dairy fat with equivalent energy intake from polyunsaturated fatty acid (PUFA) or vegetable fat was associated with 24% (RR: 0.76; 95% CI: 0.71, 0.81) and 10% (RR: 0.90; 95% CI: 0.87, 0.93) lower risk of CVD, respectively, whereas the 5% energy intake substitution of other animal fat with dairy fat was associated with 6% increased CVD risk (RR: 1.06; 95% CI: 1.02, 1.09).

CONCLUSIONS

The replacement of animal fats, including dairy fat, with vegetable sources of fats and PUFAs may reduce risk of CVD. Whether the food matrix may modify the effect of dairy fat on health outcomes warrants further investigation.

Impact of single anaerobic exercise on delayed activation of endothelial xanthine oxidase in men and women

OBJECTIVES

The aim of the study was to evaluate the activity of xanthine oxidase (XO) in the blood of men and women during the first hour following a single anaerobic exercise (AN-EX), and after 24 hours of recovery, and to determine whether the changes in XO activity in the blood after AN-EX are dependent on anaerobic performance.

METHODS

Ten men and ten women performed a single AN-EX. Blood was collected before and five times after completion of the AN-EX. The activity of XO was determined.

RESULTS

In both groups, a significant (P < 0.05) increase in blood XO activity was found only 24 hours after the AN-EX. The increased activity of XO in men was significantly lower than in women (P < 0.05). Negative correlations were found between the increase in XO activity in the blood plasma 24 hours after the AN-EX and anaerobic power, the total work performed during the AN-EX and the power decrease.

DISCUSSION

In the first hour after the single AN-EX, XO activity in the blood of women and men did not change, but after 24 hours of recovery, it was significantly higher compared to baseline levels in both sexes. Single AN-EX causes a smaller increase in XO activity in people with higher anaerobic performance.

Gout and rheumatoid arthritis, both to keep in mind in cardiovascular risk management: A primary care retrospective cohort study

OBJECTIVES

To assess in one time window cardiovascular risks for both patients with gout and patients with rheumatoid arthritis in a Dutch primary care population.

METHODS

Retrospective matched cohort study with data from the electronic health records of 51 Dutch general practices. Participants were patients aged 30 years or older with an incident diagnosis of gout (n=2655) or rheumatoid arthritis (n=513), and matched non-disease controls (n=7891 and n=1850 respectively). At disease incidence date, patients and controls were compared for prevalence of hypertension, diabetes mellitus, hypercholesterolemia, and prior cardiovascular diseases. Patients without prior cardiovascular disease were followed for a first cardiovascular disease, and compared to controls using Kaplan-Meier survival curves and Cox proportional hazard analyses.

RESULTS

Compared to controls, gout patients suffered more from hypertension (44.8%), diabetes (20.1%), hypercholesterolemia (13.7%), and prior cardiovascular disease (30%) (P<0.01), whereas rheumatoid arthritis patients (hypertension 28.5%; diabetes 11.7%; hypercholesterolemia 7.4%; prior cardiovascular disease 11.3%) did not (P>0.05). After adjustment, both gout and rheumatoid arthritis patients without prior cardiovascular disease were more likely to get a cardiovascular disease: hazard ratio (95% confidence interval) 1.44 (1.18 to 1.76), and 2.06 (1.34 to 3.16) respectively.

CONCLUSIONS

This primary care study indicates that gout and rheumatoid arthritis are both independent risk factors for cardiovascular diseases, rheumatoid arthritis to some greater extent, whereas gout patients at first diagnosis had already an increased cardiovascular risk profile. It gives strong arguments for implementation of both rheumatic diseases in primary care guidelines on cardiovascular risk management.

Allopurinol decreases serum uric acid level and intestinal glucose transporter-5 expression in rats with fructose-induced hyperuricemia

BACKGROUND

High fructose consumption is considered to be related to the increasing prevalence of hyperuricemia (HUA). Glucose transporters (GLUT) 2 and 5 are crucial for fructose absorption and transporter. Effects of anti-HUA drugs, allopurinol (API) and benzbromarone (BBR), on expressions of GLUT5 and GLUT2 are not evaluated.

METHOD

Wistar rats were given 10% fructose in drinking water for 60 days to induce HUA, and 5mg/kg API and 10mg/kg BBR were intragastricly treated for 30 days. Serum level of uric acid and xanthine oxidase (XOD) activity in liver were determined. Expressions of GLUT2 and GLUT5 in intestine were analyzed by immunohistochemistry staining assay and Western blot assay.

RESULTS

Treatment with API or BBR significantly decreased the serum level of uric acid in HUA rats induced by fructose. Meanwhile, API treatment significantly reduced the XOD activity in liver and GLUT5 expression in intestine. However, BBR treatment did not show inhibitory effects on hepatic XOD activity and intestinal GLUT5 expression. In addition, treatment with API or BBR did not show any effect on GLUT2 expression in intestine.

CONCLUSION

API decreases serum level of uric acid in fructose-induced HUA rats. The mechanisms are associated with suppressing XOD activity in liver to reduce uric acid production, and inhibiting GLUT5 expression in intestine to reduce fructose absorption.

Randomized control trial for the assessment of the anti-albuminuric effects of topiroxostat in hyperuricemic patients with diabetic nephropathy (the ETUDE study)

Proteinuria is an established risk factor for diabetic nephropathy. Recent studies indicate that some xanthine oxidase inhibitors have a renoprotective effect. The aim of this study was to assess whether topiroxostat reduces albuminuria in hyperuricemic patients with diabetic nephropathy and overt proteinuria. The ETUDE study is an ongoing 24-week, multicenter, open-label, randomized (1:1), parallel group study involving hyperuricemic patients with diabetic nephropathy (estimated glomerular filtration rate [eGFR] ≥ 20 mL/min/1.73 m(2)) and overt proteinuria (0.3 ≤ urine protein to creatinine ratio (UPCR) < 3.5 g/g Cr). Patients are randomly assigned to high dose (topiroxostat 160 mg daily) or low dose (topiroxostat 40 mg daily) on top of standard of care. The primary endpoint is the change in albuminuria indicated by urine albumin-to-creatinine ratio after 24 treated weeks relative to the baseline values. This trial was registered at the Japanese University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR: UMIN 000015403). The background, rationale, and study design of this trial are presented here. Seventy-six patients from four registered facilities have already been enrolled and received at least one dose of topiroxostat. This trial will end in 2017. The ETUDE trial is the first randomized controlled study of topiroxostat in hyperuricemic patients with diabetic nephropathy and overt proteinuria. We will clarify the pleiotropic function of topiroxostat including an anti-albumiuric effect as well as its effects on safely decreasing serum uric acid levels.

Hepatic and seric levels of purines in rats experimentally infected by Fasciola hepatica

The aim of this study was to evaluate hepatic and seric levels of purines, as well as their breakdown products in rats infected by Fasciola hepatica on days 15 and 87 post-infection (PI). Rats were divided into two groups: uninfected (n = 10) and infected (n = 20). On day 15 (n = 5 for uninfected group and n = 10 for infected group) and 87 PI (n = 5 for uninfected group and n = 10 for infected group), animals were euthanized for sampling to evaluate levels of purines by high-performance liquid chromatography. In serum, ATP increased (P < 0.05) and ADP decreased (P < 0.05) on days 15 and 87 PI, while AMP increased (P < 0.05) only on day 15 PI. Hypoxanthine levels increased (P < 0.05) on days 15 and 87 PI, while adenosine and xanthine levels decreased and increased (P < 0.05), respectively, on day 87 PI. No difference was observed regarding seric inosine and uric acid (P > 0.05). Hepatic ATP, adenosine, and uric acid levels decreased (P < 0.05) on days 15 and 87 PI. AMP levels decreased (P < 0.05) on day 87 PI, while xanthine levels increased (P < 0.05) on day 15 PI in the liver. Also in the liver, hypoxanthine levels increased (P < 0.05) on day 15 PI and decreased (P < 0.05) on day 87 PI. On the other hand, there was no difference on hepatic ADP and inosine levels (P > 0.05). Therefore, it is possible to conclude that F. hepatica infection can change purine levels, which may be associated with an inflammatory process, and these alterations may influence fasciolosis pathogenesis.

Miracle Fruit (Synsepalum dulcificum) Exhibits as a Novel Anti-Hyperuricaemia Agent

Miracle fruit (Synsepalum dulcificum) belongs to the Sapotaceae family. It can change flavors on taste buds, transforming acidic tastes to sweet. We evaluated various miracle fruit extracts, including water, butanol, ethyl acetate (EA), and hexane fractions, to determine its antioxidant effects. These extracts isolated from miracle fruit exerted potential for reduction of uric acid and inhibited xanthine oxidase activity in vitro and in monosodiumurate (MSU)-treated RAW264.7 macrophages. Moreover, we also found that the butanol extracts of miracle fruit attenuated oxonic acid potassium salt-induced hyperuricaemia in ICR mice by lowering serum uric acid levels and activating hepatic xanthine oxidase. These effects were equal to those of allopurinol, suggesting that the butanol extract of miracle fruit could be developed as a novel anti-hyperuricaemia agent or health food.

Xanthine Oxidase Activity in Type 2 Diabetes Mellitus Patients with and without Diabetic Peripheral Neuropathy

This study investigated the relationship between serum xanthine oxidase (XOD) activity and the occurrence of diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) patients. Serum XOD activity, ischemia-modified albumin (IMA), uric acid (UA), albumin, glycated hemoglobin (HbA1c), advanced glycation end products (AGE), total free thiols, atherogenic index of plasma (AIP), and body mass index (BMI) were measured in 80 T2DM patients (29 with and 51 without DPN), and 30 nondiabetic control subjects. Duration of diabetes, hypertension, medication, and microalbuminuria was recorded. Serum XOD activities in controls, non-DPN, and DPN were 5.7 ± 2.4 U/L, 20.3 ± 8.6 U/L, and 27.5 ± 10.6 U/L (p < 0.01), respectively. XOD activity was directly correlated to IMA, UA, BMI, HbA1c, and AGE, while inversely correlated to serum total free thiols. A multivariable logistic regression model, which included duration of diabetes, hypertension, AIP, HbA1c, UA, and XOD activity, revealed HbA1c [OR = 1.03 (1.00-1.05); p = 0.034] and XOD activity [OR = 1.07 (1.00-1.14); p = 0.036] as independent predictors of DPN. Serum XOD activity was well correlated to several other risk factors. These results indicate the role of XOD in the development of DPN among T2DM patients.

Green tea polyphenols decreases uric acid level through xanthine oxidase and renal urate transporters in hyperuricemic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Green tea is a Chinese materia medica with the main functions of "inducing urination and quenching thirst". Green tea polyphenols (GTP) are generally acknowledged as the main active fraction with multiple pharmacological functions in green tea. However, the effect of GTP on hyperuricemia is not clear till now.

AIM OF STUDY

The present study was carried out to investigate the effect of GTP on serum level of uric acid in potassium oxonate (PO)-induced hyperuricemic mice, and explore the underlying mechanisms from two aspects of production and excretion of uric acid.

MATERIALS AND METHODS

PO and GTP were intragastricly administered to mice for consecutive 7 days. Serum level of uric acid, and xanthine oxidase (XOD) activity in serum and liver were examined. Simultaneously, expression of XOD protein in liver was analyzed by Western blot assay. Expressions of urate transporters including urate-anion transporter (URAT) 1, organic anion transporter (OAT) 1 and 3 in kidney were analyzed by immunohistochemistry staining method.

RESULTS

300 and 600 mg/kg GTP significantly decreased serum level of uric acid of hyperuricemic mice in a dose-dependent manner (p<0.05 or p<0.01). Besides, 300 and 600 mg/kg GTP markedly reduced XOD activity in serum and liver of hyperuricemic mice (both p<0.01). Furthermore, 300 and 600 mg/kg GTP clearly reduced XOD expression in liver, as well as reduced URAT1 expression and increased OAT1 and OAT3 expressions in kidney of hyperuricemic mice (p<0.05 or p<0.01).

CONCLUSIONS

These results demonstrated that GTP had the effect of lowering uric acid through decreasing the uric acid production and increasing uric acid excretion. Our study suggested that GTP would be a promising candidate as a novel hypouricaemic agent for further investigation.

Serum and aqueous xanthine oxidase levels, and mRNA expression in anterior lens epithelial cells in pseudoexfoliation

PURPOSE

The aim of this study was to determine serum and aqueous xanthine oxidase (XO) levels, and mRNA expression in anterior lens epithelial cells in pseudoexfoliation (PEX).

METHODS

In this prospective study, serum, aqueous and anterior lens capsules were taken from 21 patients with PEX and 23 normal subjects who had undergone routine cataract surgery. Serum and aqueous XO levels were analyzed using the colorimetric method. mRNA expression of XO in anterior lens epithelial cells was evaluated using reverse transcription polymerase chain reaction analysis.

RESULTS

Serum XO levels (means ± standard deviations) were 207.0 ± 86.1 IU/mL and 240.6 ± 114.1 IU/mL in the normal and PEX groups, respectively (p = 0.310). Aqueous XO levels (means ± standard deviations) were 65.5 ± 54.3 IU/mL in the normal group and 130.5 ± 117.4 IU/mL in the PEX group (p = 0.028). There was a 2.9 fold decrease in mRNA expression in anterior lens epithelial cells of PEX, which is significantly lower than the normal group (p = 0.01).

CONCLUSIONS

Higher aqueous XO levels lacking associated different serum XO suggests higher oxidative stress in the aqueous. Higher aqueous XO levels in PEX with decreased mRNA expression in anterior lens epithelial cells indicate possible overexpression of XO in other structures related to the aqueous.