Gout and hyperuricemia

ARISTOLOCHIA BRACTEOLATE RETZ. ATTENUATES HYPERURICEMIA IN A METABOLIC ARTHRITIS RAT MODEL

Background:

The leaves of Aristolochia bracteolata Retz. has been documented in the folk medicine literature for its anti-arthritic activity. The target of the research envisaged was to elucidate the activity of A. bracteolata extract on hyperuricemic condition in arthritis rat model.

Materials and Methods:

Dried and powdered plant leaves were extracted using ether and chloroform. Potassium oxonate was injected intra-articularly to produce arthritis. The hyperuricemic effect, of A. bracteolate was analyzed by studying levels of uric acid in serum as well as in urine of arthritis induced rats. Effects of plant extracts were also studied on BUN (blood urea nitrogen) levels and fraction of uric acid excreted.

Results:

Results indicate that administration of A. bracteolata presented substantial change in uric acid concentration, augmented by potassium oxonate administration in rats. The reduction in levels of uric acid levels was nearly same as allopurinol. The investigation also revealed that the primary plant extract has nephroprotective effect by enhancing the production of Prostaglandin E₂ and Interleukin-1. Histological studies of rat kidney slices indicated the safety of the present plant extract.

Conclusion:

The crude extract of A. bracteolate can be used to reduce hyperuricemia in metabolic arthritis produced in rat model, without inducing any potential damaging effects.

Effects of Gnaphalium affine D. Don on hyperuricemia and acute gouty arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

The Gnaphalium affine D. Don is used in China as a folk medicine to treat gout, anti-inflammatory, antitussive and expectorant activities. The aim of this study was to evaluate the potential of the extract of G. affine to treat hyperuricemia and acute gouty arthritis in animal model.

MATERIALS AND METHODS

G. affine extract was evaluated in an experimental model with potassium oxonate (PO) induced hyperuricemia in mice which was used to evaluate anti-hyperuricemia activity and xanthine oxidase (XO) inhibition. Therapies for acute gouty arthritis was also investigated on monosodium urate (MSU) crystal induced paw edema model.

RESULTS

G. affine extract showed expressive results on active in reducing serum uric acid (Sur) through effect renal mGLUT9 and mURAT1 mainly and inhibit XO activity in vivo. The extract of G. affine also showed significant anti-inflammatory activity and reduced the paw swelling on MSU crystal-induced paw edema model. Meanwhile, eight major compounds were identified by HPLC-ESI-QTOF-MS/MS.

CONCLUSIONS

The extract of G. affine showed significant effect on evaluated models and therefore may be active agents for the treatment of hyperuricemia and acute gouty arthritis.

Combined effect of obesity and uric acid on nonalcoholic fatty liver disease and hypertriglyceridemia

Hyperuricemia is associated with metabolic syndrome (MetS), but the association is often confounded by the shared background of obesity. We sought to explore the modifying effects of obesity on the association between uric acid (UA), MetS components, and nonalcoholic fatty liver disease (NAFLD).We conducted a cross-sectional study in a Chinese population of 10,069 participants aged ≥20 years. Multiplicative interaction between obesity (BMI ≥25 kg/m) and elevated UA was assessed using an interaction term in a logistic regression analysis. The presence of additive interaction was assessed based on the relative excess risk due to the interaction (RERI) and the attributable proportion due to the interaction (AP).There was no evidence of a multiplicative interaction between obesity and elevated UA on MetS components and NAFLD. However, there was a strong additive interaction between obesity and elevated UA with regard to NAFLD (RERI of 6.47 [95% CI 3.42-9.53] for men and 5.87 [1.55-10.19] for women) and hypertriglyceridemia (RERI of 1.38 [0.57-2.20] for men and 1.38 [0.08-2.67] for women). In addition, 42% and 36% of the increased odds of NAFLD for men and women, respectively, can be explained by an interaction between obesity and elevated UA (AP of 0.42 [95% CI (0.30-0.54)] for men and 0.36 [0.17-0.55] for women). Similarly, the interaction accounted for 27% and 26% of the increased risk of hypertriglyceridemia for men and women (AP of 0.27 [0.14-0.41] for men and 0.26 [0.06-0.47] for women).In this population, obesity and elevated UA synergistically interacted to increase the risk of NAFLD and hypertriglyceridemia.

Frequency of Serum Creatinine Monitoring During Allopurinol Therapy in Ambulatory Patients

Background:

Allopurinol dosage reduction is recommended in patients with renal dysfunction because drug toxicity risk is increased. Little information is available about serum creatinine (SCr) monitoring in ambulatory patients taking allopurinol.

Objective:

To evaluate SCr monitoring among patients prescribed allopurinol, identify associated factors, and evaluate administrative data in assessing monitoring.

Methods:

Information for this retrospective cohort study was drawn from a dataset of 2 020 037 individuals; approximately 200 000 members from each of 10 organizations. Study patients had received at least one year of ongoing allopurinol prescription dispensings. Patient variables analyzed included age, gender, chronic diseases, outpatient visits, hospitalizations, gout diagnosis, and SCr monitoring. A random sample of medical records was reviewed to assess the accuracy of the automated data. Statistical analysis included descriptive and logistic regression techniques.

Results:

Overall, 1139 (26%) of 4357 patients did not have SCr monitoring. For individuals without recent hospitalization, factors protective against lack of monitoring were increasing age (OR 0.77 per 10 y; 95% CI 0.74 to 0.79), more chronic diseases (OR 0.81; 95% CI 0.78 to 0.83), more outpatient visits (OR 0.87 per 5 visits; 95% CI 0.83 to 0.91), and gout diagnosis (OR 0.74; 95% CI 0.65 to 0.85). The sensitivity and specificity of administrative data compared with medical records for SCr monitoring were 92% and 65%, respectively.

Conclusions:

More than one-fourth of patients dispensed allopurinol did not have SCr monitoring during one year of therapy. Lack of monitoring and lack of subsequent possible dosage adjustment put patients at increased risk of allopurinol toxicity.

Update on the Clinical Effect of Acupuncture Therapy in Patients with Gouty Arthritis: Systematic Review and Meta-Analysis

Objective. The aim of this study is to evaluate the clinical efficacy and safety of acupuncture therapy in the treatment of acute gouty arthritis. Methods. A literature search of PubMed, EMBASE, ISI Web of Science, CENTRAL, and CNKI was conducted from the inception date of each database up to October 2015. Two investigators screened each article independently and were blinded to the findings of the other reviewer. Data was extracted according to the predetermined collection form. Meta-analysis was performed. Results. We analyzed data from 28 RCTs involving 2237 patients with gouty arthritis. Compared with conventional pharmacological treatments acupuncture was more effective in rendering patients free from symptoms after 24 hours, lowering serum urate, alleviating pain associated with gouty arthritis, and decreasing the ESR; regarding CRP, no statistically significant difference was found. In addition, the frequency of adverse events in acupuncture treatment was lower than that in control group. Conclusion. Based on the findings of our study, we cautiously suggest that acupuncture is an effective and safe therapy for patients with gouty arthritis. However, the potential beneficial effect of acupuncture might be overstated due to the methodological deficiency of included studies. High quality RCTs with larger scale are encouraged.

Tuna extract reduces serum uric acid in gout-free subjects with insignificantly high serum uric acid: A randomized controlled trial

Long-term reduction of serum urate levels is vital in the treatment of gout. However, it is difficult to convince gout-free individuals of the necessity of treatment as few appropriate over-the-counter remedies and dietary supplements are available. Therefore, the present study aimed to investigate the antihyperuricemic efficacy and safety of a tuna extract containing the imidazole compounds to evaluate its potential as a functional food ingredient. A randomized, 4-week, double-blind, placebo-controlled study was conducted. A total of 48 male gout-free subjects with insignificantly high serum uric acid were randomly assigned to low- and high-dose tuna extract groups or a placebo group. The efficacy of the extract was assessed by measuring serum uric acid levels. Furthermore, a safety assessment was performed by physical parameters, hematology, blood biochemistry and urinalysis. The results indicated that the uric acid level was decreased at week 4 during the intervention in the tuna extract groups (low and high dose, -0.23 and -0.34 mg/dl, respectively) compared to the placebo group (-0.07 mg/dl). At week 4 after the intervention, a significant reduction in uric acid levels (-0.41 mg/dl; P<0.05) was observed in the high-dose tuna extract group compared with the placebo group (+0.11 mg/dl). No dose-related adverse events were observed during and following the intervention. Therefore, the present results suggest that oral administration of tuna extract containing the imidazole compounds has hypouricemic activity with no undesirable side effects.

Cost-effectiveness analysis of febuxostat in patients with gout in Spain

Objectives Cost-effectiveness of febuxostat compared with allopurinol in the treatment of hyperuricemia in patients with gout. Methods Costs, clinical outcomes, and QALYs were estimated using a Markov model. Febuxostat 80 mg and 120 mg sequentially, used as first line and second line therapy, was compared with allopurinol 300 mg. Patients switched to the next treatment in the sequence according to a dichotomous response vs no response (target serum urate level < 6 mg/dl outcome) after 3 months of active treatment. A 3% discount rate and 5-year time horizon were applied.

PERSPECTIVE

National Health System. Results The addition of febuxostat to any therapeutic strategy was an efficient option, with incremental cost-effectiveness ratios (ICER) compared with allopurinol 300 mg ranging from €5268-€9737. Conclusions Febuxostat is a cost-effective treatment in Spain for the management of hyperuricemia in gout patients, with ICERs far below accepted Spanish efficiency thresholds (30 000€/QALY).

Metabolically healthy obesity also has risk for hyperuricemia among Chinese general population: A cross-sectional study

INTRODUCTION

The metabolically healthy obese (MHO) refers to obese individuals with a favorable metabolic profile. It is unknown whether metabolically healthy status in persons with obesity or overweight decreases the risk of hyperuricemia. This study aims to explore the association of MHO with risk of hyperuricemia.

METHODS

We performed a cross-sectional study including 11,435 (5300 men and 6135 women) general population aged ≥35 years in Liaoning Province. Anthropometric measurements, laboratory examinations and self-reported information on lifestyle factors were collected by trained personnel. Metabolically healthy overweight/obesity was defined according to body mass index and ATP-III criterion of metabolically healthy status. Hyperuricemia was defined as SUA ≥7mg/dl (420mmol/L) in men or ≥6mg/dl (360mmol/L) in women. Logistic regression analyses were performed to explore the association between overweight/obesity with different metabolic status and risk of hyperuricemia.

RESULTS

Among total subjects, 470 (4.2%) were metabolically healthy obese (MHO) and 1567 (14.0%) were metabolically unhealthy obese (MUO). For metabolically healthy female participants, the prevalence of hyperuricemia with overweight was similar to with a normal BMI (2.5% vs. 3.1%, P=0.314). Multivariate logistic regression analyses showed that MHO (OR=2.48, 95% CI: 1.81-3.41) and MUO (OR=4.81, 95% CI: 3.97-5.83) were significantly associated with hyperuricemia. However, the odds ratio in females with metabolically healthy overweight was 0.85 (95% CI: 0.53-1.37).

CONCLUSIONS

Metabolically healthy might decline the risk of hyperuricemia, but overweight and obesity with metabolically healthy had also strong associations with hyperuricemia, except in females with metabolically healthy overweight.

Rapid and reliable genotyping of HLA-B*58:01 in four Chinese populations using a single-tube duplex real-time PCR assay

AIM

HLA-B*58:01 is strongly associated with allopurinol-induced severe cutaneous adverse reactions. This study aimed to develop a new and convenient method for HLA-B*58:01 genotyping and to investigate HLA-B*58:01 distribution in different Chinese populations.

MATERIALS & METHODS

Combining of sequence-specific primers and TaqMan probe, a single-tube duplex real-time PCR assay for HLA-B*58:01 typing was established.

RESULTS

The HLA-B*58:01 genotyping result in Buyei (n = 100) by real-time PCR showed 100% concordance with those by sequence-based typing. The prevalence of HLA-B*58:01 carrier in Buyei (17%, n = 100) was significantly higher than those in Northern Han (4%, n = 100), Tibetan (5.1%, n = 99) and Uighur (2%, n = 50) populations (p < 0.05).

CONCLUSION

The newly developed reliable assay was appropriate for HLA-B*58:01 detection prior to allopurinol administration in clinical settings.

Hyperuricaemia: contributions of urate transporter ABCG2 and the fractional renal clearance of urate

OBJECTIVE

To investigate the contributions towards hyperuricaemia of known risk factors, focusing on fractional (renal) clearance of urate (FCU) and variation in the ATP-binding cassette transporter, sub-family G 2 (ABCG2) gene.

METHODS

The contributions of age, sex, ancestry, Q141K genotype for ABCG2, FCU, sugar-sweetened beverage and alcohol consumption, metabolic syndrome disorders and measures of renal function to the risk of hyperuricaemia were evaluated by comparing hyperuricaemic (serum urate≥0.42 mmol/L, n=448) with normouricaemic (serum urate<0.42 mmol/L, n=344) participants using stepwise logistic regression. Model performance was evaluated using the area under the receiver operator characteristic curve (AUROC).

RESULTS

ABCG2 genotype, FCU, male sex, body mass index, serum triglyceride concentrations, estimated glomerular filtration rate and consumption of alcohol were the best predictors of hyperuricaemia (AUROC 0.90, 81% accuracy). Homozygosity in the 141K variant for ABCG2 conferred an adjusted OR of 10.5 for hyperuricaemia (95% CI 2.4 to 46.2). For each 1% decrease of FCU, the adjusted OR increased by 51% (OR 1.51, 95% CI 1.37 to 1.66). There was no association between ABCG2 genotype and FCU (r=0.02, p=0.83).

CONCLUSIONS

The ABCG2 141K variant and the FCU contribute strongly but independently to hyperuricaemia. These findings provide further evidence for a significant contribution of ABCG2 to extra-renal (gut) clearance of urate.

Risks associated with drug treatments for kidney stones

INTRODUCTION

Renal stones are one of the most painful medical conditions patients experience. For many they are also a recurrent problem. Fortunately, there are a number of drug therapies available to treat symptoms as well as prevent future stone formation.

AREAS COVERED

Herein, we review the most common drugs used in the treatment of renal stones, explaining the mechanism of action and potential side effects. Search of the Medline databases and relevant textbooks was conducted to obtain the relevant information. Further details were sourced from drug prescribing manuals. Recent studies of drug effectiveness are included as appropriate.

EXPERT OPINION

Recent controversies include medical expulsive therapy trials and complex role of urinary citrate in stone disease. Future directions in research will involve new medical therapies for stone prevention, for example new drugs for hyperoxaluria.

Stevens-Johnson syndrome and toxic epidermal necrolysis: an update on pharmacogenetics studies in drug-induced severe skin reaction

Stevens-Johnson syndrome and toxic epidermal necrolysis are severe, life-threatening drug reactions involving skin and membranes mucous, which are associated with significant morbidity and mortality and triggered, especially by drug exposure. Different studies have demonstrated that drug response is a multifactorial character and that the interindividual variability in this response depends on both environmental and genetic factors. The last ones have a relevant significance. In fact, the identification of new specific genetic markers involved in the response to drugs, will be of great utility to establish a more personalized therapeutic approach and to prevent the appearance of these adverse reactions. In this review, we summarize recent progresses in the Pharmacogenetics studies related to Stevens-Johnson syndrome/toxic epidermal necrolysis reporting the major genetic factors identified in the last years as associated with the disease and highlighting the use of some of these genomic variants in the clinical practice.

rs9263726 is a specific genetic marker for allopurinol-induced severe cutaneous adverse reactions in Chinese patients

Aim: Screening of an easily detectable biomarker to replace the HLA allele B variant (HLA-B*58:01) testing for predicting allopurinol-induced severe cutaneous adverse reactions (SCARs) in eastern Chinese patients. Methods: Six SNPs and the HLA-B*58:01 were analyzed in 17 patients with allopurinol-induced SCARs and in 151 control patients. SNPs were analyzed by pyrosequencing, and HLA-B*58:01 was evaluated by sequencing-based techniques. Consistency between sequencing-based HLA-B*58:01 testing and pyrosequencing-based rs9263726 testing was investigated in 262 individuals. Results: A significant association with allopurinol-induced SCARs was found at rs9263726 (odds ratio: 108.8) and HLA-B*58:01 (odds ratio: 108.8). The kappa values between sequencing-based HLA-B*58:01 testing and pyrosequencing-based rs9263726 testing were 0.96 (>0.75), demonstrating they were well coincident with each other. Conclusion: rs9263726 was a useful surrogate of HLA-B*58:01 testing for prescreening allopurinol-induced SCARs in eastern Chinese patients.

Study on the anti-gout activity of chlorogenic acid: improvement on hyperuricemia and gouty inflammation

Gout is a metabolic disorder associated with hyperuricemia resulting in the deposition of monosodium urate (MSU) crystals in joints and tissues. Lowering serum uric acid (Sur) levels and anti-inflammation are highly essential in treating gout. Chlorogenic acid (CA), as one of the most abundant polyphenols in the Chinese medicines, has been rarely reported to have an anti-gout effect. The model of potassium oxonate (PO)-induced hyperuricemia in mice and MSU crystal-induced inflammation in rats has been established in this study. The potential beneficial effects and mechanisms of CA on hyperuricemia and gouty arthritis were elucidated. The results demonstrated that CA significantly decreased the Sur level by inhibiting the xanthine oxidase (XOD) activity but not increasing the urinary uric acid (Uur) level. In addition, CA also exhibited the effect of suppressing paw swelling. Further investigation indicated that CA improved the symptoms of inflammation induced by MSU crystals by inhibiting the production of proinflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The present study suggests that CA may have a considerable potential for development as an anti-gouty arthritis agent for clinical application.

Research on Susceptible Genes and Immunological Pathogenesis of Cutaneous Adverse Drug Reactions in Chinese Hans

Cutaneous adverse drug reactions (cADRs) include mild maculopapular exanthems (MPE), Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalized exanthematous pustulosis (AGEP). We used HLA high-resolution genotyping and genome wide association analysis (GWAS) to identify the genetic markers for cADRs induced by common culprit drugs in Han Chinese population. To further understand the immunopathogenesis of cADRs, and with the goal of developing treatment strategies, we compared the expression of cytoxic cytokines between the patients with cADRs and normal controls. Our data suggested that the carbamazepine induced SJS/TEN, allopurinol induced CADRs, methazolamide induced SJS/TEN and SASP induced DRESS were respectively strongly associated with HLA-B*15:02, HLA-B*58:01, HLA-B*59:01 and HLA-B*13:01. In addition, increased expression of cytotoxic cytokines in sera and tissues of cADRs patients were found, compared with healthy controls. Our findings may shed light on prediction and prevention of cADRs, provide clues to pathogenesis, and guide treatment strategies of these reactions.

Genome-wide association study of clinically defined gout identifies multiple risk loci and its association with clinical subtypes

OBJECTIVE

Gout, caused by hyperuricaemia, is a multifactorial disease. Although genome-wide association studies (GWASs) of gout have been reported, they included self-reported gout cases in which clinical information was insufficient. Therefore, the relationship between genetic variation and clinical subtypes of gout remains unclear. Here, we first performed a GWAS of clinically defined gout cases only.

METHODS

A GWAS was conducted with 945 patients with clinically defined gout and 1213 controls in a Japanese male population, followed by replication study of 1048 clinically defined cases and 1334 controls.

RESULTS

Five gout susceptibility loci were identified at the genome-wide significance level (p<5.0×10(-8)), which contained well-known urate transporter genes (ABCG2 and SLC2A9) and additional genes: rs1260326 (p=1.9×10(-12); OR=1.36) of GCKR (a gene for glucose and lipid metabolism), rs2188380 (p=1.6×10(-23); OR=1.75) of MYL2-CUX2 (genes associated with cholesterol and diabetes mellitus) and rs4073582 (p=6.4×10(-9); OR=1.66) of CNIH-2 (a gene for regulation of glutamate signalling). The latter two are identified as novel gout loci. Furthermore, among the identified single-nucleotide polymorphisms (SNPs), we demonstrated that the SNPs of ABCG2 and SLC2A9 were differentially associated with types of gout and clinical parameters underlying specific subtypes (renal underexcretion type and renal overload type). The effect of the risk allele of each SNP on clinical parameters showed significant linear relationships with the ratio of the case-control ORs for two distinct types of gout (r=0.96 [p=4.8×10(-4)] for urate clearance and r=0.96 [p=5.0×10(-4)] for urinary urate excretion).

CONCLUSIONS

Our findings provide clues to better understand the pathogenesis of gout and will be useful for development of companion diagnostics.

An effective strategy to prevent allopurinol-induced hypersensitivity by HLA typing

PURPOSE

This study was conducted to evaluate the usefulness of human leukocyte antigen (HLA) typing in preventing allopurinol-induced severe cutaneous adverse reactions (SCARs) through the application of an allopurinol tolerance induction protocol or prescription of other alternative medications in high-risk patients.

METHODS

HLA typing was performed in patients with chronic renal insufficiency who needed allopurinol. HLA-B*58:01-negative patients were prescribed the usual dose of allopurinol. For HLA-B*58:01-positive patients, administration of either allopurinol based on a 28-day tolerance induction protocol or alternative medications was initiated. Hypersensitivity reactions were surveyed for 90 days and compared with the result of a previous retrospective cohort study.

RESULTS

Among a total of 401 study subjects, no SCARs were noted in HLA-B*58:01-positive patients with application of the tolerance induction protocol (n = 30) or alternative medications (n = 16), nor were any SCARs observed in HLA-B*58:01-negative patients who started allopurinol at the usual dose (n = 355). Compared with the previous retrospective cohort study, a significant reduction in SCARs was observed in HLA-B*58:01-positive patients (0 vs. 18%; P = 0.002).

CONCLUSION

This study shows the usefulness of HLA-B*58:01 screening in identifying patients at high risk for the development of allopurinol-induced SCARs and suggests that application of a tolerance induction protocol or alternative medications could be an effective strategy to prevent allopurinol-induced SCARs in HLA-B*58:01-positive patients.

Febuxostat for the treatment of gout

INTRODUCTION

Gout is a rheumatologic condition associated with elevated serum uric acid levels and deposition of monosodium urate crystals in joints and soft tissues. The xanthine oxidase inhibitor, allopurinol, has historically been the principle agent utilized for reducing elevated uric acid levels and treating underlying cause of gout symptoms; the availability of febuxostat, a newer non-purine selective xanthine oxidase inhibitor, represents an alternative therapy for those patients with contraindications or intolerance to allopurinol.

AREAS COVERED

This article reviews the published literature on the pharmacologic characteristics and clinical safety and efficacy data on the use of febuxostat in the treatment of gout. A literature search of MEDLINE and MEDLINE In-Process & Other Non-Indexed Citations Databases (1996-November 2014) was conducted utilizing the key words 'febuxostat', 'allopurinol', and 'gout'. All published articles regarding febuxostat were evaluated. References of selected articles, data from poster presentations, and abstract publications were additionally reviewed.

EXPERT OPINION

Febuxostat has shown benefit with respect to symptomatic relief and uric acid level reduction. The safety profile of this agent makes it an ideal alternative in those patients with contraindications to or who are intolerant of allopurinol.

Effects of anthocyanins from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) on the serum uric acid level and xanthine oxidase activity in hyperuricemic mice

This study was aimed at evaluating the hypouricemic effect of the anthocyanin-rich purple sweet potato extract (APSPE).

[Metabolic complications after renal transplantation from a living donor: experience of the Ibn Sina university hospital of Rabat]

La transplantation rénale (TR) constitue le traitement de choix de l'insuffisance rénale chronique terminale. Les complications métaboliques après TR (diabète, dyslipidémie, hyperuricémie, obésité), en grande partie liées au traitement immunosuppresseur, deviennent une préoccupation car elles constituent un facteur de risque de morbimortalité et de perte fonctionnelle du greffon. Le but de notre étude est d’évaluer la fréquence de ces anomalies après TR. Il s'agit d'une étude rétrospective incluant tous les patients ayant bénéficié d'une première TR par donneur vivant (DV) de Juin 1998 à Décembre 2010. Nous avons recensé les données démographiques propres au receveur, le traitement immunosuppresseur après TR. Les paramètres clinico-biologiques recueillis sont (index de masse corporel (IMC), glycémie à jeun, hémoglobine glyquée, CT, C-HDL, C-LDL, TG, acide urique). Soixante dix patients ont été colligés, l’âge moyen est de 36.3 + /-9.6 ans (21 à 62) avec un sex ratio de 0.5. Quinze patients (21.4%) étaient hypertendus avant la TR et 2.9% avaient une néphropathie diabétiques. L’âge moyen du donneur est de 47.5 + /-10.2 ans (20-65). Le traitement immunosuppresseur pendant la phase d'induction était une trithérapie associant corticostéroïdes, anticalcineurines chez tous les patients et mycophénolate mofétil chez 68.6% et azathioprine dans 31.4% des cas. L'IMC moyen était de 24.1 + /-4.0 (16.9 à 37), 33% des patients étaient considérés en surpoids dont 21.8% en obésité. L'hypercholestérolémie, a été retrouvée chez 25 patients soit 36%. Presque la moitié des patients (48.5%) avaient une hyperuricémie. Quatre patients ont développé un diabète après TR soit 6% des cas. La perte du greffon a été notée chez 12 patients et 2 patients sont décédés dont un avec un greffon fonctionnel. En analyse univariée, l'hyperuricémie et la dyslipidémie ont été considérées comme facteur de risque de perte du greffon et retour en dialyse avec p = 0.024 et 0.021 respectivement. Les complications métaboliques après TR sont fréquentes et méritent une attention particulière car elles représentent un facteur de morbi-mortalité. L’éducation précoce du patient greffé est nécessaire et s'appuie sur une prise en charge multidisciplinaire impliquant les néphrologues, diététiciennes, psychologues et médecins généralistes.

Allopurinol for chronic gout

BACKGROUND

Allopurinol, a xanthine oxidase inhibitor, is considered one of the most effective urate-lowering drugs and is frequently used in the treatment of chronic gout.

OBJECTIVES

To assess the efficacy and safety of allopurinol compared with placebo and other urate-lowering therapies for treating chronic gout.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE on 14 January 2014. We also handsearched the 2011 to 2012 American College of Rheumatology (ACR) and European League against Rheumatism (EULAR) abstracts, trial registers and regulatory agency drug safety databases.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-randomised controlled clinical trials (CCTs) that compared allopurinol with a placebo or an active therapy in adults with chronic gout.

DATA COLLECTION AND ANALYSIS

We extracted and analysed data using standard methods for Cochrane reviews. The major outcomes of interest were frequency of acute gout attacks, serum urate normalisation, pain, function, tophus regression, study participant withdrawal due to adverse events (AE) and serious adverse events (SAE). We assessed the quality of the body of evidence for these outcomes using the GRADE approach.

MAIN RESULTS

We included 11 trials (4531 participants) that compared allopurinol (various doses) with placebo (two trials); febuxostat (four trials); benzbromarone (two trials); colchicine (one trial); probenecid (one trial); continuous versus intermittent allopurinol (one trial) and different doses of allopurinol (one trial). Only one trial was at low risk of bias in all domains. We deemed allopurinol versus placebo the main comparison, and allopurinol versus febuxostat and versus benzbromarone as the most clinically relevant active comparisons and restricted reporting to these comparisons here.Moderate-quality evidence from one trial (57 participants) indicated allopurinol 300 mg daily probably does not reduce the rate of gout attacks (2/26 with allopurinol versus 3/25 with placebo; risk ratio (RR) 0.64, 95% confidence interval (CI) 0.12 to 3.52) but increases the proportion of participants achieving a target serum urate over 30 days (25/26 with allopurinol versus 0/25 with placebo, RR 49.11, 95% CI 3.15 to 765.58; number needed to treat for an additional beneficial outcome (NNTB) 1). In two studies (453 participants), there was no significant increase in withdrawals due to AE (6% with allopurinol versus 4% with placebo, RR 1.36, 95% CI 0.61 to 3.08) or SAE (2% with allopurinol versus 1% with placebo, RR 1.93, 95% CI 0.48 to 7.80). One trial reported no difference in pain reduction or tophus regression, but did not report outcome data or measures of variance sufficiently and we could not calculate the differences between groups. Neither trial reported function.Low-quality evidence from three trials (1136 participants) indicated there may be no difference in the incidence of acute gout attacks with allopurinol up to 300 mg daily versus febuxostat 80 mg daily over eight to 24 weeks (21% with allopurinol versus 23% with febuxostat, RR 0.89, 95% CI 0.71 to 1.1); however more participants may achieve target serum urate level (four trials; 2618 participants) with febuxostat 80 mg daily versus allopurinol 300 mg daily (38% with allopurinol versus 70% with febuxostat, RR 0.56, 95% CI 0.48 to 0.65, NNTB with febuxostat 4). Two trials reported no difference in tophus regression between allopurinol and febuxostat over a 28- to 52-week period; but as the trialists did not provide variance, we could not calculate the mean difference between groups. The trials did not report pain reduction or function. Moderate-quality evidence from pooled data from three trials (2555 participants) comparing allopurinol up to 300 mg daily versus febuxostat 80 mg daily indicated no difference in the number of withdrawals due to AE (7% with allopurinol versus 8% with febuxostat, RR 0.89, 95% CI 0.62 to 1.26) or SAE (4% with allopurinol versus 4% with febuxostat, RR 1.13, 95% CI 0.71 to 1.82) over a 24- to 52-week period.Low-quality evidence from one trial (65 participants) indicated there may be no difference in the incidence of acute gout attacks with allopurinol up to 600 mg daily compared with benzbromarone up to 200 mg daily over a four-month period (0/30 with allopurinol versus 1/25 with benzbromarone, RR 0.28, 95% CI 0.01 to 6.58). Based on the pooled results of two trials (102 participants), there was moderate-quality evidence of no probable difference in the proportion of participants achieving a target serum urate level with allopurinol versus benzbromarone (58% with allopurinol versus 74% with benzbromarone, RR 0.79, 95% CI 0.56 to 1.11). Low-quality evidence from two studies indicated there may be no difference in the number of participants who withdrew due to AE with allopurinol versus benzbromarone over a four- to nine-month period (6% with allopurinol versus 7% with benzbromarone, pooled RR 0.80, 95% CI 0.18 to 3.58). There were no SAEs. They did not report tophi regression, pain and function.All other comparisons were supported by small, single studies only, limiting conclusions.

AUTHORS' CONCLUSIONS

Our review found low- to moderate-quality evidence indicating similar effects on withdrawals due to AEs and SAEs and incidence of acute gout attacks when allopurinol (100 to 600 mg daily) was compared with placebo, benzbromarone (100 to 200 mg daily) or febuxostat (80 mg daily). There was moderate-quality evidence of little or no difference in the proportion of participants achieving target serum urate when allopurinol was compared with benzbromarone. However, allopurinol seemed more successful than placebo and may be less successful than febuxostat (80 mg daily) in achieving a target serum urate level (6 mg/dL or less; 0.36 mmol/L or less) based on moderate- to low-quality evidence. Single studies reported no difference in pain reduction when allopurinol (300 mg daily) was compared with placebo over 10 days, and no difference in tophus regression when allopurinol (200 to 300 mg daily) was compared with febuxostat (80 mg daily). None of the trials reported on function, health-related quality of life or participant global assessment of treatment success, where further research would be useful.

Allopurinol induced erythroderma

Allopurinol, a widely prescribed urate lowering agent is responsible for various adverse drug reactions, including erythroderma. A 45-year-old male patient was admitted with the complaints of fever, redness and scaling all over the body after 3-4 weeks of allopurinol treatment for asymptomatic hyperuricemia. Elevated liver enzymes were detected in his blood analysis. Skin biopsy was consistent with drug induced erythroderma. Allopurinol was stopped and steroids were started. Patient improved over a period of 2 weeks.

Colchicine for acute gout

BACKGROUND

This is an update of a Cochrane review first published in 2006. Gout is one of the most common rheumatic diseases worldwide. Despite the use of colchicine as one of the first-line therapies for the treatment of acute gout, evidence for its benefits and harms is relatively limited.

OBJECTIVES

To evaluate the benefits and harms of colchicine for the treatment of acute gout.

SEARCH METHODS

We searched the following electronic databases from inception to April 2014: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We did not impose any date or language restrictions in the search. We also handsearched conference proceedings of the American College of Rheumatology and the European League against Rheumatism (2010 until 2013) and reference lists of identified studies. We searched the clinical trials register clinicaltrials.gov and the WHO trials register.

SELECTION CRITERIA

We considered published randomised controlled trials (RCTs) and controlled clinical trials (CCTs) evaluating colchicine therapy compared with another therapy (active or placebo) in acute gout. The primary benefit outcome of interest was pain, defined as a proportion with 50% or greater decrease in pain, and the primary harm outcome was study participants withdrawal due to adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results for relevant studies, extracted data into a standardised form and assessed the risk of bias of included studies. We pooled data if deemed to be sufficiently clinically homogeneous. We assessed the quality of the body of evidence for each outcome using the GRADE approach.

MAIN RESULTS

Two RCTs (124 participants) were included in this updated review, including one new RCT. We considered one trial to be at low risk of bias, while we considered the newly included trial to be at unclear risk of bias. Both trials included a placebo and a high-dose colchicine arm, although the colchicine regimens varied. In one trial 0.5 mg colchicine was given every two hours until there was either complete relief of symptoms or toxicity and the total doses were not specified. In the other trial a total of 4.8 mg colchicine was given over six hours. The newly identified trial also included a low-dose colchicine arm (total 1.8 mg over one hour).Based upon pooled data from two trials (124 participants), there is low-quality evidence that a greater proportion of people receiving high-dose colchicine experience a 50% or greater decrease in pain from baseline up to 32 to 36 hours compared with placebo (35/74 in the high-dose colchicine group versus 12/50 in the placebo group (risk ratio (RR) 2.16, 95% confidence interval (CI) 1.28 to 3.65), with a number needed to treat to benefit (NNTB) of 4 (95% CI 3 to 12). However, the total number of adverse events (diarrhoea, vomiting or nausea) is greater in those who receive high-dose colchicine versus placebo (62/74 in the high-dose colchicine group versus 11/50 in the placebo group (RR 3.81, 95% CI 2.28 to 6.38), with a number needed to treat to harm (NNTH) of 2 (95% CI 2 to 5). Only one trial included reduction of inflammation as part of a composite measure comprising pain, tenderness, swelling and erythema, each graded on a four-point scale (none 0 to severe 3) to derive a maximum score for any one joint of 12. They reported the proportion of people who achieved a 50% reduction in this composite score. Based upon one trial (43 participants), there was low-quality evidence that more people in the high-dose colchicine group had a 50% or greater decrease in composite score from baseline up to 32 to 36 hours than people in the placebo group (11/22 in the high-dose colchicine group versus 1/21 in the placebo group (RR 10.50, 95% CI 1.48 to 74.38) and 45% absolute difference).Based upon data from one trial (103 participants), there was low-quality evidence that low-dose colchicine is more efficacious than placebo with respect to the proportion of people who achieve a 50% or greater decrease in pain from baseline to 32 to 36 hours (low-dose colchicine 31/74 versus placebo 5/29 (RR 2.43, 95% CI 1.05 to 5.64)), with a NNTB of 5 (95% CI 2 to 20). There are no additional harms in terms of adverse events (diarrhoea, nausea or vomiting) with low-dose colchicine compared to placebo (19/74 and 6/29 respectively (RR 1.24, 95% CI 0.55 to 2.79)).Based upon data from one trial (126 participants), there is low-quality evidence that there are no additional benefits in terms of the proportion of people achieving 50% or greater decrease in pain from baseline up to 32 to 36 hours with high-dose colchicine compared to low-dose (19/52 and 31/74 respectively (RR 0.87, 95% CI 0.56 to 1.36). However, there were statistically significantly more adverse events in those who received high-dose colchicine (40/52 versus 19/74 in the low-dose group (RR 3.00, 95% CI 1.98 to 4.54)), with a NNTH of 2 (95% CI 2 to 3).No trials reported function of the target joint, patient-reported global assessment of treatment success, health-related quality of life or withdrawals due to adverse events. We identified no studies comparing colchicine to non-steroidal anti-inflammatory drugs (NSAIDs) or other active treatments such as glucocorticoids (by any route).

AUTHORS' CONCLUSIONS

Based upon only two published trials, there is low-quality evidence that low-dose colchicine is likely to be an effective treatment for acute gout. We downgraded the evidence because of a possible risk of selection and reporting biases and imprecision. Both high and low-dose colchicine improve pain when compared to placebo. While there is some uncertainty around the effect estimates, compared with placebo, high-dose but not low-dose colchicine appears to result in a statistically significantly greater number of adverse events. Therefore low-dose colchicine may be the preferred treatment option. There are no trials about the effect of colchicine in populations with comorbidities or in comparison with other commonly used treatments, such as NSAIDs and glucocorticoids.

Evaluation of the Antihyperuricemic Activity of Phytochemicals from Davallia formosana by Enzyme Assay and Hyperuricemic Mice Model

Abnormal serum urate levels are recognized as a critical factor in the progression of several chronic diseases. To evaluate the antihyperuricemic effect of Davallia formosana, the inhibitory activities of 15 isolated phytochemicals, including five novel compounds of 6,8-dihydroxychromone-7-C-β-d-glucopyranoside (1), 6,8,3′,4′-tetrahydroxyflavanone-7-C-β-d-glucopyranoside (2), 6,8,4′-trihydroxyflavanone-7-C-β-d-glucopyranoside (3), 8-(2-pyrrolidinone-5-yl)-catechin-3-O-β-d-allopyranoside (4), and epiphyllocoumarin-3-O-β-d-allopyranoside (5), were examined against xanthine oxidase (XOD) and in a potassium oxonate-(PTO-) induced acute hyperuricemic mice model. The results indicated that compounds 3 and 5 significantly inhibited XOD activity in vitro and reduced serum uric acid levels in vivo. This is the first report providing new insights into the antihyperuricemic activities of flavonoid glycosides which can possibly be developed into potential hypouricemic agents.

Cost-effectiveness analysis of HLA-B*5801 testing in preventing allopurinol-induced SJS/TEN in Thai population

BACKGROUND

Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), caused by allopurinol therapy, are strongly associated with the human leukocyte antigen (HLA), HLA-B*5801. Identification of HLA-B*5801 genotype before prescribing allopurinol offers the possibility of avoiding allopurinol-induced SJS/TEN. As there is a paucity of evidence about economic value of such testing, this study aims to determine the cost-effectiveness of HLA-B*5801 testing compared with usual care (no genetic testing) before allopurinol administration in Thailand.

METHODS AND FINDING

A decision analytical and Markov model was used to estimate life time costs and outcomes represented as quality adjusted life years (QALYs) gained. The model was populated with relevant information of the association between gene and allopurinol-induced SJS/TEN, test characteristics, costs, and epidemiologic data for Thailand from a societal perspective. Input data were obtained from the literature and a retrospective database analysis. The results were expressed as incremental cost per QALY gained. A base-case analysis was performed for patients at age 30. A series of sensitivity analyses including scenario, one-way, and probabilistic sensitivity analyses were constructed to explore the robustness of the findings. Based on a hypothetical cohort of 1,000 patients, the incremental total cost was 923,919 THB (USD 29,804) and incremental QALY was 5.89 with an ICER of 156,937.04 THB (USD 5,062) per QALY gained. The cost of gout management, incidence of SJS/TEN, case fatality rate of SJS/TEN, and cost of genetic testing are considered very influential parameters on the cost-effectiveness value of HLA-B*5801 testing.

CONCLUSIONS

The genetic testing for HLA-B*5801 before allopurinol administration is considered a highly potential cost-effective intervention in Thailand. The findings are sensitive to a number of factors. In addition to cost-effectiveness findings, consideration of other factors including ethical, legal, and social implications is needed for an informed policy decision making.

Rhabdomyolysis associated with initiation of febuxostat therapy for hyperuricaemia in a patient with chronic kidney disease

WHAT IS KNOWN AND OBJECTIVE

Febuxostat is now recommended as the first-line pharmacological urate-lowering therapy for gout in the American College of Rheumatology guidelines. There is no case of rhabdomyolysis associated with febuxostat among reported side effects of the drug. Our objective is to report on a case of rhabdomyolysis associated with initiation of febuxostat in a patient with chronic kidney disease (CKD).

CASE SUMMARY

A 73-year-old male patient visited our emergency room due to progressive weakness in both lower extremities starting 3 days earlier. Ten days before presentation, his primary physician had changed his prescription from allopurinol to febuxostat (80 mg) because of poor control of uric acid levels. There was tenderness in both thighs. Initial creatinine kinase (CK) was 7652 U/L (0-170 U/L), and a bone scan using (99m) Tc-HDP revealed strong uptake in soft tissues in both thighs and buttocks. Electromyography (EMG) and nerve conduction velocity (NCV) showed abnormal spontaneous activities (ASA), suggesting myopathy, not nerve damage. On day 7 of admission, after conservative management and febuxostat withdrawal, he could walk on the ward. He is being followed in our clinic as an outpatient with no sequelae.

WHAT IS NEW AND CONCLUSION

This report is first case of rhabdomyolysis associated with initiation of febuxostat. Febuxostat should be withdrawn when rhabdomyolysis is confirmed.

Hyperuricemia and cardiovascular risk

There is an increasing prevalence of gout and hyperuricemia worldwide. Gout confers a significant individual and social burden and is increasingly recognized as a prevalent chronic disease state requiring appropriate long-term management. Gout and hyperuricemia appear to be independent risk factors for incident hypertension, renal disease and cardiovascular disease. Multiple epidemiologic studies confirm an association between hyperuricemia and "cardiometabolic disease". We review the evidence stating the relationship between hyperuricemia and the development of comorbid conditions contributing to cardiovascular risk and disease.

Purine derivate content and amino acid profile in larval stages of three edible insects

BACKGROUND

Considering their high content of protein, insects are a valuable alternative protein source. However, no evaluation of their purine content has so far been done. High content of purine derivates may lead to the exclusion of such food from the diet of people with specific diseases. The aim of this study was to analyse the content of selected purine derivates and amino acid profile in the three insect species most often used for entomophagy in Europe and compare them with the purine content in egg white and chicken breast.

RESULTS

The content of individual purine derivates and their total content were significantly dependent on insect species. The purine content in all three species was significantly higher (P < 0.05) than in egg white, but some values were significantly lower (P < 0.05) than in chicken breast. The total protein content was 548.9 g kg(-1) dry matter (DM) in mealworm (Tenebrio molitor), 551.6 g kg(-1) DM in superworm (Zophobas atratus) and 564.9 g kg(-1) DM in cricket (Gryllus assimilis).

CONCLUSION

Larvae of mealworm and superworm are protein-rich and purine-low meat alternatives. In contrast, cricket nymphs are protein-rich and purine-rich and cannot be recommended for people with hyperuricemia or gout.

Hyperuricemia after exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans near a highly contaminated area

BACKGROUND

Hyperuricemia (too much uric acid in the blood) is the predisposing condition for gout and is associated with hypertriglyceridemia, diabetes mellitus, and coronary artery disease. Polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) cause renal toxicity and elevate uric acid. The aim of this analysis was to investigate and clarify the effect of moderate-to-high PCDD/F exposure on hyperuricemia risk.

METHODS

In this cross-sectional study, we recruited 1531 healthy participants living near a deserted pentachlorophenol factory. We measured serum levels of 17 2,3,7,8-substituted PCDD/Fs, and then examined associations between the main predictor variable, serum TEQ(DF-2005) (total PCDD/Fs 2005 World Health Organization [WHO] toxic equivalency [TEQ]), and dependent variables such as uric acid, glomerular filtration rates, and hyperuricemia risk.

RESULTS

We observed a strong monotonic inverse relationship between serum TEQ(DF-2005) quartiles and the estimated glomerular filtration rate after adjusting for confounding factors (Men: β were 0, -4.7, -6.2, and -14.8; Women: β were 0, -6.7, -12.9, and -21.5). In addition, we observed a suggestive positive trend between serum TEQDF-2005 quartiles and uric acid only in men after adjusting for confounding factors (Men: β were 0, 0.40, 0.36, and 0.59; P for trend <0.05). Men with serum TEQ(DF-2005) higher than the reference group's (<7.4 pg WHO(2005)-TEQ(DF/g) lipid) had a higher hyperuricemia risk after adjusting for confounding factors (25th to <50th percentile, adjusted odds ratio [AOR] = 2.20 [95% confidence interval {CI} = 1.30-3.73]; 50th to <75th percentile, AOR = 1.86 [95% CI = 1.08-3.22]; ≥ 75th percentile, AOR = 3.00 [95% CI = 1.69-5.31]).

CONCLUSIONS

We conclude that serum TEQ(DF-2005) is an important determinant of serum uric acid levels and heightens the risk of hyperuricemia in general populations.

Gout as a risk factor for myocardial infarction and stroke in England: evidence from record linkage studies

OBJECTIVE

Some studies suggest that gout is a risk factor for cardiovascular disease. There is more evidence about the association between gout and acute myocardial infarction (MI) than about gout and stroke, and only limited information about risks by age group and sex. We aimed to study MI and stroke following gout, including types of stroke, by age group and comparing men and women.

METHODS

We analysed an all-England national linked dataset of hospital admissions and death records from 1999 to 2011, and a similar dataset in the Oxford Record Linkage Study spanning 1963-98. The occurrence of MI and stroke was estimated in cohorts of patients admitted to hospital with gout, compared with MI and stroke in control cohorts, and the comparisons were expressed as rate ratios (RRs).

RESULTS

The risk of MI and stroke was elevated, and similar, in both datasets. In the all-England dataset, which included 202 033 hospital patients with gout, the RR for MI following gout was 1.82 (95% CI 1.78, 1.85), for all stroke 1.71 (1.68, 1.75), ischaemic stroke 1.68 (1.64, 1.73), haemorrhagic stroke 1.69 (1.61, 1.77) and stroke of unspecified type 2.00 (1.95, 2.06). Associations were stronger in younger than older age groups, and in the younger were stronger in women than men.

CONCLUSION

Gout was associated with increased risk of stroke as well as MI. These findings should be considered by clinicians and may have implications for preventive management of circulatory disease risks in people with gout.

Arxula adeninivorans recombinant urate oxidase and its application in the production of food with low uric acid content

Hyperuricemia and its symptoms are becoming increasingly common worldwide. Elevated serum uric acid levels are caused by increased uric acid synthesis from food constituents and reduced renal excretion. Treatment in most cases involves reducing alcohol intake and consumption of meat and fish or treatment with pharmaceuticals. Another approach could be to reduce uric acid level in food, either during production or consumption. This work reports the production of recombinant urate oxidase by Arxula adeninivorans and its application to reduce uric acid in a food product. The A. adeninivorans urate oxidase amino acid sequence was found to be similar to urate oxidases from other fungi (61-65% identity). In media supplemented with adenine, hypoxanthine or uric acid, induction of the urate oxidase (AUOX) gene and intracellular accumulation of urate oxidase (Auoxp) was observed. The enzyme characteristics were analyzed from isolates of the wild-type strain A. adeninivorans LS3, as well as from those of transgenic strains expressing the AUOX gene under control of the strong constitutive TEF1 promoter or the inducible AYNI1 promoter. The enzyme showed high substrate specificity for uric acid, a broad temperature and pH range, high thermostability and the ability to reduce uric acid content in food.

Common missense variant of monocarboxylate transporter 9 (MCT9/SLC16A9) gene is associated with renal overload gout, but not with all gout susceptibility

Gout is a common disease caused by hyperuricemia, which shows elevated serum uric acid (SUA) levels. From a viewpoint of urate handling in humans, gout patients can be divided into those with renal overload (ROL) gout with intestinal urate underexcretion, and those with renal underexcretion (RUE) gout. Recent genome-wide association studies (GWAS) revealed an association between SUA and a variant in human monocarboxylate transporter 9 (MCT9/SLC16A9) gene. Although the function of MCT9 remains unclear, urate is mostly excreted via intestine and kidney where MCT9 expression is observed. In this study, we investigated the relationship between a variant of MCT9 and gout in 545 patients and 1,115 healthy volunteers. A missense variant of MCT9 (K258T), rs2242206, significantly increased the risk of ROL gout (p = 0.012), with odds ratio (OR) of 1.28, although it revealed no significant association with all gout cases (p = 0.10), non-ROL gout cases (p = 0.83), and RUE gout cases (p = 0.34). In any case groups and the control group, minor allele frequencies of rs2242206 were >0.40. Therefore, rs2242206 is a common missense variant and is revealed to have an association with ROL gout, indicating that rs2242206 relates to decreased intestinal urate excretion rather than decreased renal urate excretion. Our study provides clues to better understand the pathophysiology of gout as well as the physiological roles of MCT9.

Arxula adeninivorans recombinant adenine deaminase and its application in the production of food with low purine content

AIMS

Construction of a transgenic Arxula adeninivorans strain that produces a high concentration of adenine deaminase and investigation into the application of the enzyme in the production of food with low purine content.

METHODS AND RESULTS

The A. adeninivorans AADA gene, encoding adenine deaminase, was expressed in this yeast under the control of the strong inducible nitrite reductase promoter using the Xplor(®) 2 transformation/expression platform. The recombinant enzyme was biochemically characterized and was found to have a pH range of 5.5-7.5 and temperature range of 34-46 °C with medium thermostability. A beef broth was treated with the purified enzyme resulting in the concentration of adenine decreasing from 70.4 to 0.4 mg l(-1).

CONCLUSIONS

It was shown that the production of adenine deaminase by A. adeninivorans can be increased and that the recombinant adenine deaminase can be used to lower the adenine content in the food.

SIGNIFICANCE AND IMPACT OF THE STUDY

Adenine deaminase is one component of an enzymatic system that can reduce the production of uric acid from food constituents. This study gives details on the expression, characterization and application of the enzyme and thus provides evidence that supports the further development of the system.

Polydatin ameliorates renal injury by attenuating oxidative stress-related inflammatory responses in fructose-induced urate nephropathic mice

A series of studies have recently demonstrated that the oxidative stress, nuclear factor-kappa B (NF-κB) activation and the subsequent coordinated inflammatory responses played an important role in the pathogenesis of urate nephropathy (UN). Polydatin has been suggested to have the properties of anti-oxidative, anti-inflammatory and nephroprotective effects. However, the possible protective and beneficial effects of polydatin on UN are not fully elucidated. Therefore, we investigated the potential beneficial effects and possible mechanisms of polydatin on UN. In this study, polydatin showed inhibitory activities on xanthine oxidase to repress the level of serum uric acid in vivo and in vitro. Further investigations revealed that polydatin displayed little toxic effects and significantly ameliorated the renal function in fructose-induced UN mice. The nephroprotective activities of polydatin was not only due to the effects on remarkably attenuating the oxidative stress induced by uric acid, but also on markedly suppressing the oxidative stress-related inflammatory cascade, including decreasing the expressions of NF-κB p65, COX-2 and iNOS proteins and inhibiting the productions of TNF-α, PGE(2) and IL-1β. These findings elucidated that polydatin exhibited prominent nephroprotective activities and low toxic effects.

The uric acid metabolism pathway as a therapeutic target in hyperuricemia related to metabolic syndrome

INTRODUCTION

Uric acid (UA) increase is considered an important risk factor for the development of cardiovascular disease (CVD) favoring oxidative stress and endothelial dysfunction and is also involved in metabolic syndrome (MS) pathophysiology.

AREAS COVERED

Insulin has a physiological action on renal tubules, causing a reduction in UA clearance, what could explain the hyperuricemia found in MS. On the other hand, it was also hypothesized a causal role of UA in fructose-induced MS. Moreover, it has been suggested that higher UA levels predict the development of MS. MS subjects present a redox imbalance and UA participates in this process. UA can contribute to oxidative stress present in MS; however, it has also an important role in the antioxidant defense system. Although UA may have a protective effect due to its antioxidant properties, it is clear that the dominant effect of UA in MS is deleterious. All-cause mortality and CVD have been shown to be increased with higher UA levels.

EXPERT OPINION

It is extremely important to prescribe drugs which concomitantly decrease hyperuricemia and improve co-morbidities associated with hyperuricemia. Long-term studies to verify the consequences of decreasing UA concentration below current recommendations in asymptomatic patients are needed.

HLA-B*58:01 allele is associated with augmented risk for both mild and severe cutaneous adverse reactions induced by allopurinol in Han Chinese

Aim: Allopurinol is widely used as an effective urate-lowering drug and is one of the most frequent causes of cutaneous adverse drug reactions (cADRs). Recently, a strong association of HLA-B*58:01 with allopurinol-induced severe cADRs was identified. This study investigated the predisposition to different types of allopurinol-cADRs conferred by HLA-B*5801 in a Han population from mainland China. Patients & methods:HLA-B genotyping was performed on 38 Chinese patients with different types of allopurinol-cADRs from 2008 to 2011. Results: All the allopurinol-cADR patients carried HLA-B*58:01, in contrast with only 11.11% (7/63) in the allopurinol-tolerant patients (odds ratio [OR] = 580.07; p < 0.0001) and 13.99% (80/572) in a Han Chinese population from the human MHC database (dbMHC; OR: 471.09; p < 0.0001) carried the genotype. Each type of allopurinol cADRs revealed a statistically significant association with HLA-B*58:01. In particular, the risk of allopurinol-induced maculopapular eruption was significantly higher in patients with HLA-B*58:01 (OR: 339.00; p < 0.0001). Conclusion: The strong association of both the mild and severe types of allopurinol cADRs with the HLA-B*58:01 allele were observed. The results indicated that the prospective use of a genetic test of HLA-B*58:01 might reduce the prevalence of allopurinol-induced cADRs.

Original submitted 7 March 2012; Revision submitted 21 May 2012

Association between HLA-B*58:01 allele and severe cutaneous adverse reactions with allopurinol in Han Chinese in Hong Kong

BACKGROUND

Allopurinol has been reported as a common cause of severe cutaneous adverse reactions (SCARs). Recent studies in various populations suggest that HLA-B*58:01 is a strong genetic marker for allopurinol-induced SCAR, especially in populations with a high frequency of HLA-B*58:01.

OBJECTIVES

To confirm the association link between HLA-B*58:01 and hypersensitivity reactions attributed to allopurinol use in Han Chinese patients in Hong Kong.

METHODS

We performed a case-control study to investigate whether the HLA-B*58:01 allele predisposes to allopurinol-induced SCAR in Han Chinese patients in Hong Kong. The HLA-B*58:01 genotyping was performed in 20 patients with allopurinol-induced SCAR or erythema multiforme major (EMM; n = 1) and in 30 patients tolerant to allopurinol.

RESULTS

All of the 19 patients with allopurinol-induced SCAR examined but not the patient with EMM carried HLA-B*58:01 whereas only four (13%) of the control patients had this allele. The positive rate of the HLA-B*58:01 was significantly higher in the cases than in the allopurinol-tolerant control group [odds ratio (OR) 123·5, 95% confidence interval (CI) 12·8-1195·1; P < 1 × 10(-4) ] and was even higher after removal of the patient with EMM (OR 229·7, 95% CI 11·7-4520·4). The sensitivity and specificity of the HLA-B*58:01 allele for prediction of allopurinol-induced SCAR were 100% and 86·7%, respectively.

CONCLUSIONS

This study confirmed the strong association between the HLA-B*58:01 and allopurinol-induced SCAR in Hong Kong Han Chinese patients. A screening test for the HLA-B*58:01 allele should effectively reduce the risk for allopurinol-induced SCAR in Chinese populations.

Decreased extra-renal urate excretion is a common cause of hyperuricemia

ABCG2, also known as BCRP, is a high-capacity urate exporter, the dysfunction of which raises gout/hyperuricemia risk. Generally, hyperuricemia has been classified into urate 'overproduction type' and/or 'underexcretion type' based solely on renal urate excretion, without considering an extra-renal pathway. Here we show that decreased extra-renal urate excretion caused by ABCG2 dysfunction is a common mechanism of hyperuricemia. Clinical parameters, including urinary urate excretion, are examined in 644 male outpatients with hyperuricemia. Paradoxically, ABCG2 export dysfunction significantly increases urinary urate excretion and risk ratio of urate overproduction. Abcg2-knockout mice show increased serum uric acid levels and renal urate excretion, and decreased intestinal urate excretion. Together with high ABCG2 expression in extra-renal tissues, our data suggest that the 'overproduction type' in the current concept of hyperuricemia be renamed 'renal overload type', which consists of two subtypes-'extra-renal urate underexcretion' and genuine 'urate overproduction'-providing a new concept valuable for the treatment of hyperuricemia and gout.