Apolipoprotein E phenotypes in patients with gout: relation with hypertriglyceridaemia

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

Background

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

Methods

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

Results

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

Conclusion

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

Comparative analysis of anthropometric indices with serum uric acid in Iranian healthy population

BACKGROUND

The relationship between elevated serum uric acid (SUA) levels and hypertension, metabolic syndrome and cardiovascular disease has been established. In this study, the relation of SUA levels to anthropometric indices, blood cell count and lipid profile was examined.

METHODS

Anthropometric parameters including body-mass index, waist circumference, waist to height ratio, waist to hip ratio, waist to pelvic ratio, neck circumference (NC), body fat mass (BFM), basal metabolic rate (BMR), visceral fat level (VFL) and percent body fat (PBF), along with complete blood cell count, lipid profile and SUA were obtained from 2921 young and middle-aged Iranian healthy subjects. To assess the normality of data, the Kolmogorov-Smirnov test was used. Mann-Whitney, Kruskal-Wallis, Chi-square and Spearman correlation tests were used for evaluating the association between variables. Simple and multiple regression analyses were also performed.

RESULTS

The results of data analysis showed all studied factors were correlated with SUA level except VFL, BFM, and platelet-to-lymphocyte ratio. The highest correlation was with NC, BMR, hematocrits (HCT) and triglycerides (TG). The backward method revealed that TG, LDL, HDL, neutrophil, lymphocyte, platelet, HCT, BMR and skinfold fat thickness were factors related to SUA.

CONCLUSIONS

According to the finding of this study, SUA level is related to anthropometric indices, lipid profile and neutrophil to lymphocyte ratio in healthy population. SUA measurement might be advisable to identify those at increased risk of health problems whom might benefit from further evaluation.

Urate-induced epigenetic modifications in myeloid cells

OBJECTIVES

Hyperuricemia is a metabolic condition central to gout pathogenesis. Urate exposure primes human monocytes towards a higher capacity to produce and release IL-1β. In this study, we assessed the epigenetic processes associated to urate-mediated hyper-responsiveness.

METHODS

Freshly isolated human peripheral blood mononuclear cells or enriched monocytes were pre-treated with solubilized urate and stimulated with LPS with or without monosodium urate (MSU) crystals. Cytokine production was determined by ELISA. Histone epigenetic marks were assessed by sequencing immunoprecipitated chromatin. Mice were injected intraarticularly with MSU crystals and palmitate after inhibition of uricase and urate administration in the presence or absence of methylthioadenosine. DNA methylation was assessed by methylation array in whole blood of 76 participants with normouricemia or hyperuricemia.

RESULTS

High concentrations of urate enhanced the inflammatory response in vitro in human cells and in vivo in mice, and broad-spectrum methylation inhibitors reversed this effect. Assessment of histone 3 lysine 4 trimethylation (H3K4me3) and histone 3 lysine 27 acetylation (H3K27ac) revealed differences in urate-primed monocytes compared to controls. Differentially methylated regions (e.g. HLA-G, IFITM3, PRKAB2) were found in people with hyperuricemia compared to normouricemia in genes relevant for inflammatory cytokine signaling.

CONCLUSION

Urate alters the epigenetic landscape in selected human monocytes or whole blood of people with hyperuricemia compared to normouricemia. Both histone modifications and DNA methylation show differences depending on urate exposure. Subject to replication and validation, epigenetic changes in myeloid cells may be a therapeutic target in gout.

Factors Influencing the Serum Uric Acid in Gout with Cerebral Infarction

Background

Although the relationship between gout and cardiovascular has been well demonstrated, there is little information about the difference between gout with cerebrovascular disease and cardiovascular disease. In this study, the differences between gout with cerebral infarction (gout+CI) and gout with coronary heart disease (gout+CHD) and related factors that affect serum uric acid (sUA) levels in gout+CI were investigated by a cross-sectional study.

Method

The patients from Jiangxi Provincial People's Hospital with gout+CHD, gout+CI, and gout with coronary heart disease and cerebral infarction (gout+CHD+CI) between 2016 and 2020 were included in this study, and the medical record data were collected and analyzed.

Results

We observed significant differences in age, drinking, hypertension, long-term use of diuretics and NSAIDs, sUA, CRE, and blood glucose in patients with gout+CHD and gout+CI. The sUA level was significantly positively correlated with smoking, CRE, and TG in the gout+CI group and was only positively correlated with CRE in the gout+CHD group and the gout+CHD+CI group (p < 0.05). Interestingly, the sUA level was only negatively correlated with the age and gender in the gout+CI group (p < 0.05). After excluding factors with no significant statistical effect, only age, gender, smoking, CRE, and TG were included in the multiple linear regression model. It suggested that smoking, CRE, and TG are positively correlated with the sUA level, while age was negatively correlated with the sUA level.

Conclusions

There are many discrepancies in clinical characteristics between gout+CHD patients and gout+CI patients, especially that the factors that affect UA levels are significantly different. The data also suggested that uric acid-lowering therapy may need to be strengthened in the young gout+CI patients with a history of smoking.

Synergistic association of changes in serum uric acid and triglycerides with changes in insulin resistance after walking exercise in community-dwelling older women

INTRODUCTION

Serum uric acid (SUA) and triglyceride (TG) levels are strongly correlated with insulin resistance; however, the association after a walking exercise program in community-dwelling older women has not been investigated.

METHODS

The present study included 100 postmenopausal women (mean ± standard deviation, 68 ± 7 years) from a rural village in Japan. The Nordic walking program of 120 min per week was performed for 12 weeks. Before and after the intervention, SUA, TG, various relevant factors and homeostasis model assessment of insulin resistance (HOMA-IR) were measured.

RESULTS AND CONCLUSIONS

Multivariate linear regression analysis showed that baseline TG and γ-glutamyltransferase (GGT) were significantly associated with baseline HOMA-IR. After the 12-week training program, changes in TG, SUA and GGT were significantly associated with changes in HOMA-IR. In addition to their direct associations, we observed a synergistic association between changes in TG and SUA and changes in HOMA-IR. Participants were divided into three groups (tertiles) according to changes in TG and SUA. The tertiles of changes in SUA correlated significantly with changes in HOMA-IR in participants in the tertile with the greatest decrease in TG (r = 0.525, p = 0.001), but not in the other two tertiles of change in TG (r = 0.049, p = 0.699). There was a significant interaction between SUA and TG for changes in HOMA-IR (β = 0.281, p = 0.005). These results suggest that changes in TG and SUA are synergistic factors associated with changes in insulin resistance after a 12-week walking exercise program in community-dwelling older women.

Association of apolipoprotein E (ApoE) polymorphisms with risk of primary hyperuricemia in Uygur men, Xinjiang, China

BACKGROUND

Apolipoprotein E (ApoE) participates in lipoprotein metabolism and immune regulation. This study assessed association between ApoE polymorphisms with hyperuricemia and uric acid metabolism in Uygur men, Xinjiang, China.

METHODS

A total of 474 hyperuricemia patients and 518 healthy male controls were recruited from the Health Screening Center, Uygur region of Xinjiang, China and subjected to ApoE genotyping using a multiplex amplification refractory mutation system PCR.

RESULTS

Apolipoprotein E3/3 genotype was the predominant type with a frequency of 67.7%, while E2/2 was lower than E4/4 in Uygur males. The frequencies of ApoE2, E3, and E4 alleles were 8.5%, 80.1% and 11.4%, respectively. Distribution of ApoE genotypes was significantly different in hyperuricemia patients from the healthy controls (p<0.001). Particularly, the frequency of ApoE E3/3 was 71.7%, E2/3 9.3%, E3/4 9.3%, E4/4 3.2%, E2/4 2.3%, and E2/2 0.2% in patients vs. 68.1%, 4.6%, 2.9%, 12%, 0.6%, and 4.6% in controls, respectively. Moreover, frequency of ApoE E2 allele was greater in the healthy controls than in patients (p<0.001) and the highest level of uric acid occurred in those with ApoE2/4 and E3/4 genotypes, whereas the lowest uric acid level occurred in those with ApoE E2/2 genotype. In addition, the subjects with the ApoE2 allele had a lower uric acid and LDL-C level than those with the ApoE3 allele and ApoE4 allele (p<0.05). The risk of developing hyperuricemia in subjects without the ApoE2 allele was 1.7 fold higher than those subjects with the ApoE2 allele.

CONCLUSIONS

This study revealed frequencies and distributions of ApoE alleles and genotypes in Uygur males, which are different from Han Chinese. ApoE E4 was associated with a slightly higher risk of primary hyperuricemia, whereas ApoE E2 was associated with reduced risk of primary hyperuricemia and LDL-C level.

Relationship between hyperuricemia and lipid profiles in US adults

Background. Although the link between hyperuricemia and metabolic syndrome had been recognized, the association of the dyslipidemia among individuals with hyperuricemia remains not comprehensively assessed. Methods. Using NHANES III study, we examined the relation between serum lipid profiles and different serum uric acid levels, including serum total cholesterol, LDL cholesterol, triglycerides, HDL cholesterol, apolipoprotein-B, lipoprotein (a), apolipoprotein AI, ratio of triglycerides to HDL cholesterol, and ratio of apolipoprotein-B to AI. Results. After adjusting for potential confounders, average differences (95% confidence interval) comparing the top to the bottom (reference) serum uric acid were 0.29 (0.19, 0.39) mmol/L for total cholesterol, 0.33 (0.26, 0.41) mmol/L for triglycerides, 0.14 (0.01, 0.27) mmol/L for LDL cholesterol, −0.08 (−0.11, −0.05) mmol/L for HDL, and 0.09 (0.05, 0.12) g/L for serum apolipoprotein-B. Notably, ratios of triglycerides to HDL cholesterol and apolipoprotein-B to AI were also linearly associated with uric acid levels (P for trend < 0.001). Conclusions. This study suggested that serum LDL cholesterol, triglycerides, total cholesterol, apolipoprotein-B levels, ratio of triglycerides to HDL cholesterol, and ratio of apolipoprotein-B to AI are strongly associated with serum uric acid levels, whereas serum HDL cholesterol levels are significantly inversely associated. In the clinical practice, the more comprehensive strategic management to deal with dyslipidemia and hyperuricemia deserves further investigation.

The prevalence of hyperuricemia and its correlates in an inland Chinese adult population, urban and rural of Jinan

Economy has developed rapidly in China, and the clustering of cardiovascular risk factors in subjects increased remarkably over the past two decades. However, no data are available regarding the temporal prevalence of hyperuricemia and its correlates in this rapidly developing area, especially in the inland area. The cross-sectional survey was based on a random sample of 4,218 residents aged 35-64 years in the Jinan area. Hyperuricemia was defined as serum uric acid ≥ 416 μmol/L in men and ≥ 357 μmol/L in women. Subjects underwent physical examination and fasting blood testing. Complete data were available for analysis from 1,979 men and 2,062 women. The age-adjusted prevalence of hyperuricemia was 6.4 % for men and 2.1 % for women. The prevalence of hyperuricemia was greater in urban (6.7 %) than in rural areas (1.7 %) of Jinan city. Multivariate logistic regression models revealed hyperuricemia associated with hypertriglyceridemia [men: odds ratio (OR) = 6.101, 95 % confidence interval (CI) 4.064-9.159; women: OR = 7.103, 95 % CI 3.578-14.099] and high serum creatinine level (men: OR = 2.603, 95 % CI 1.602-4.230; women: OR = 5.237, 95 % CI 2.667-10.284). Hyperuricemia was also significantly associated with male sex, urban residence, hypertension, obesity, and hypercholesterolemia. Age (1-year increase) was negatively associated with hyperuricemia in men but positively associated with hyperuricemia in women. In conclusion, the prevalence of hyperuricemia is higher in urban than rural areas of Jinan, China. Male sex, urban residence, hypertension, obesity, hypercholesterolemia, hypertriglyceridemia, and high serum creatinine level contributed to hyperuricemia in this population.

Cross-sectional and longitudinal associations between serum uric acid and metabolic syndrome

Research on the importance of serum uric acid (SUA) as a contributing metabolic factor to cardiovascular diseases has conducted to conflicting results, with most studies assuming a cross-sectional design. The aim of this study was to evaluate the association of SUA and metabolic syndrome (MetS) and its features. A representative sample of 2,485 individuals aged ≥18 years was randomly selected from the non-institutionalized resident population of Porto, Portugal. A total of 1,054 eligible subjects were included for the longitudinal analyses. Hyperuricemia was defined as SUA ≥70 mg/L in men and ≥60 mg/L in women. MetS was defined according the Joint Interim (2009) criteria. Associations were estimated using Poison regression and binomial models. In the cross-sectional analysis, subjects with hyperuricemia had a 2.10-fold increased risk of MetS as compared with normouricemic subjects (PR = 2.10, 95% CI: 1.68-2.63). Among MetS features, high triglycerides presented the strongest association with hyperuricemia (PR = 2.32, 95% CI: 1.84-2.91). The MetS crude incidence rate was 4.5/100 person-year (95% CI: 3.9-5.2) in normal uricemic and 13.0/100 person-year (95% CI: 8.5-20.0) in hyperuricemic participants. Using a multivariate longitudinal approach, hyperuricemia was positively associated with MetS incidence rate ratios (IRR = 1.73, 95% CI: 1.08-2.76). One standard deviation increase of SUA concentration was associated with a 1.22-fold increase in MetS risk (IRR = 1.22, 95% CI: 1.05-1.42). Elevated SUA presented the strongest association with high-triglycerides concentration (IRR = 1.44, 95%: 1.22-1.71) and waist circumference (IRR = 1.25, 95%: 1.05-1.49). The independent positive association between SUA and MetS suggested by this longitudinal study supports that SUA might be a risk factor for MetS.

Serum uric acid level in acute stroke patients

BACKGROUND

The role of uric acid as a risk factor for vascular disease and acute stroke is controversial and there is little information about it. In this study, we determined serum uric acid levels in patients with acute stroke and assessed its relationship with cerebrovascular risk factors.

METHODS

In this cross sectional study, we assessed patients with acute stroke who were admitted in Firoozgar Hospital from September 2010 to March 2011. Clinical records of patients and their serum uric acid level was investigated. Finally, collected data were analyzed using SPSS software Ver.16.

RESULTS

Fifty five patients with acute stroke were evaluated who 25 of these patients (45.5%) were female and 30 of them (54.5%) were male. The mean age of patients was 67±14 years. Mean serum uric acid levels in the patients studied 5.94±1.70 mg/dl, and about half of the patients (47.3%) were hyperuricemic. There was a significant negative correlation between age of patients and their serum uric acid level (p=0.04, R =-0.27). Uric acid level was significantly higher in men than women (p=0.03). Hyperuricemia was associated with increased amounts of triglycerides and Low-density lipoprotein (LDL) cholesterol (p=0.03, p=0.02). In patients with acute stroke, there was no significant association between serum uric acid level and diabetes mellitus, hypertension, history of ischemic heart disease, smoking, prescription rTPA, and type of stroke.

CONCLUSION

Due to the high prevalence of hyperuricemia in patients with acute stroke, and its accompanying increase in triglyceride and LDL cholesterol levels, it can be considered as a risk factor for acute stroke.

Relation of uric acid with components of metabolic syndrome before and after Roux-en-Y gastric bypass in morbidly obese subjects

OBJECTIVE: The purpose of the study was to investigate the prevalence of hyperuricemia in morbidly obese subjects before and after Roux-en-Y gastric bypass (RYGBP) and its relationship with metabolic syndrome abnormalities. SUBJECTS AND METHOD: We evaluated 420 morbidly obese patients. Pre and postoperative (8 months after RYGBP) blood samples were drawn. Obese patients underwent laparoscopic RYGBP and after eight months all the tests were repeated. RESULTS: The overall prevalence of hyperuricemia was 34.28%. Hyperuricemia was more common in men than in women (51.72 vs. 29.72%; p = 0.0002). Men with hyperuricemia were more likely to have diabetes (p = 0.034) and more elevated fasting plasma glucose levels (p = 0.027). Women with hyperuricemia were more likely to have hypertension (p = 0.003), metabolic syndrome (p = 0.001), elevated triglycerides (p = 0.001) and GGT (p = 0.009), and decreased HDL (p = 0.011). After surgery, uric acid levels decreased from 5.60 ± 1.28 to 4.23 ± 1.20 (p < 0.0001). The prevalence of hyperuricemia decreased from 33.6% to 6.4% (p < 0.0001), in men from 48.3% to 17.2% (p < 0.0001) and in women from 29.7% to 3.6% (p < 0.0001). CONCLUSION: Concentrations of uric acid were associated with the prevalence of metabolic abnormalities in this sample of morbidly obese patients. Also, weight loss after RYGBP can reduce uric acid levels and the prevalence of hyperuricemia.

Serum urate is not associated with coronary artery calcification: the NHLBI Family Heart Study

OBJECTIVE

urate may have effects on vascular remodeling and atherosclerosis. We had shown an association between serum uric acid (SUA) and carotid atherosclerotic plaques. Inflammation and vascular remodeling in atherosclerosis promote coronary artery calcification (CAC), a preclinical marker for atherosclerosis. Here, we examined whether SUA is associated with CAC, using the same study sample and methods as for our previous carotid atherosclerosis study.

METHODS

the national Heart, Lung, and Blood Institute Family Heart Study is a multicenter study designed to assess risk factors for heart disease. Participants were recruited from population-based cohorts in the US states of Massachusetts, North Carolina, Minnesota, Utah, and Alabama. CAC was assessed with helical computed tomography (CT). We conducted sex-specific and family-cluster analyses, as well as additional analyses among persons without risk factors related to both cardiovascular disease and hyperuricemia, adjusting for potential confounders as we had in the previous study of carotid atherosclerosis.

RESULTS

for the CAC study, 2412 subjects had both SUA and helical CT results available (55% women, age 58 ± 13 yrs, body mass index 27.6 ± 5.3). We found no association of SUA with CAC in men or women [OR in men: 1.0, 1.11, 0.86, 0.90; women: 1.0, 0.83, 1.00, 0.87 for increasing categories of SUA: < 5 (referent group), 5 to < 6, 6 to < 6.8, ≥ 6.8 mg/dl, respectively], nor in subgroup analyses.

CONCLUSION

replicating the methods used to demonstrate an association of SUA with carotid atherosclerosis did not reveal any association between SUA and CAC, suggesting that SUA likely does not contribute to atherosclerosis through effects on arterial calcification. The possibility that urate has divergent pathophysiologic effects on atherosclerosis and artery calcification merits further study.

Analysis of the relationship of leptin, high-sensitivity C-reactive protein, adiponectin, insulin, and uric acid to metabolic syndrome in lean, overweight, and obese young females

OBJECTIVE

Over the last decade there has been a steady rise in obesity and co-morbidity, but little is known about the rate of metabolic dysfunction among young adults in the United Arab Emirates. Various factors have been implicated as biomarkers of metabolic syndrome. The objective of this study was to analyze the relationships of leptin, C-reactive protein (CRP), adiponectin, insulin, and uric acid to the metabolic syndrome components in lean, overweight, and obese young females.

METHODS

This was a cross-sectional study of 69 apparently healthy young females, who were classified according to their body mass index (BMI) (kg/m(2)) into three groups: lean (<or=25), overweight (>25 and <30), and obese (>or=30). Estimated biomarkers were: leptin, insulin, adiponectin, high-sensitivity [hs]-CRP, uric acid, blood sugar, high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol, and triglycerides (TG). Anthropometric measures, blood pressure, and homeostasis model assessment-insulin resistance (HOMA-IR) were also measured.

RESULTS

Serum leptin, hs-CRP, insulin, and uric acid increased significantly (p < 0.01) with increased BMI. Only one significant correlation (p < 0.05) between the biomarkers and the metabolic syndrome components was found in lean subjects (leptin vs. waist circumference r = 0.48) as opposed to six in the obese group (hs-CRP vs. waist circumference and systolic blood pressure [SBP], r = 0.45 and r = -0.41, respectively; insulin vs. diastolic blood pressure [DBP], r = 0.47; adiponectin vs. blood sugar, r = -0.44; and uric acid vs. waist circumference and TG, r = 0.5 and r = 0.51, respectively).

CONCLUSION

Estimation of the levels of studied biomarkers could be an important tool for early detection of metabolic syndrome before the appearance of its frank components. Uric acid seems to be the most reliable biomarker to identify obese subjects with metabolic syndrome.

APOE distribution in world populations with new data from India and the UK

BACKGROUND

The APOE gene and its protein product is associated with a number of plasma proteins like very-low density lipoprotein (VLDL), high density lipoprotein (HDL) chylomicrons, chylomicron remnants, and plays a crucial role in lipid metabolism. The APOE gene is polymorphic and common alleles (*E2, *E3 and *E4) have been associated with a number of common and complex diseases in different populations. Due to their crucial role in metabolism and clinical significance, it is imperative that allelic variation in different populations is analysed to evaluate the usage of APOE in an evolutionary and clinical context.

AIM

We report allelic variation at the APOE locus in three European and four Indian populations and evaluate global patterns of genetic variation at this locus. The large, intricate and unexpected heterogeneity of this locus in its global perspective may have insightful consequences, which we have explored in this paper.

SUBJECT AND METHODS

Apolipoprotein E genotypes were determined in four population groups (Punjabi Sikhs, Punjabi Hindus, Maria Gonds and Koch, total individuals = 497) of India and three regionally sub-divided British populations (Nottinghamshire, East Midlands and West Midlands, total individuals = 621). The extent and distribution of APOE allele frequencies were compared with 292 populations of the world using a variety of multivariate methods.

RESULTS

Three alleles, APOE*E2, APOE*E3 and APOE*E4, were observed with contrasting variation, although *E4 was absent in the tribal population of Koch. Higher heterozygosities (>43%) in British populations reflected their greater genetic diversity at this locus. The overall pattern of allelic diversity among these populations is comparable to many European and Indian populations. At a global level, higher frequencies of the *E2 allele were observed in Africa and Oceania (0.099 +/- 0.083 and 0.111 +/- 0.052, respectively). Similarly, *E4 allele averages were higher in Oceania (0.221 +/- 0.149) and Africa (0.209 +/- 0.090), while Indian and Asian populations showed the highest frequencies of *E3 allele. The coefficient of gene differentiation was found to be highest in South America (9.6%), although the highest genetic diversity was observed in Oceania (48.7%) and Africa (46.3%). APOE*E2 revealed a statistically significant decreasing cline towards the north in Asia (r = -0.407, d.f. = 70, p < 0.05), which is not compatible with the coronary heart disease statistics in this continent. APOE*E4 showed a significant increasing cline in North European populations. Spatial autocorrelation analysis shows that the variation at this locus is influenced by 'isolation by distance' with a strong positive correlation for lower distances up to 1313 km.

CONCLUSION

Overall APOE allelic variation in UK and Indian populations is comparable to previous studies but in tribal populations *E4 allele frequency was very low or absent. At a global level allelic variation shows that geography, isolation by distance, genetic drift and possibly pre-historical selection are responsible for shaping the spectrum of genetic variation at the APOE gene. Overall, APOE is a good anthropogenetic and clinical diagnostic marker.

Gout and coronary artery disease: epidemiologic clues

Gout is the leading cause of inflammatory arthritis, typically affecting men and characterized by intermittent, abrupt onset of intense inflammation. The association between gout, atherosclerosis, and vascular disease has been noted in medical literature since the end of the 19th century, yet it has not been well studied. This review critically appraises the few epidemiologic studies that ask if gout is a risk factor for coronary artery disease. An exhaustive literature search using search engines and cross-referencing found four major studies and several smaller studies that have evaluated gout as a risk factor for coronary artery disease. The available studies were too heterogeneous to permit formal meta-analysis. Although there are gaps in evidence pointing to a causative pathway, overall, evidence exists for a relationship between gouty arthritis and coronary artery disease independent of traditional risk factors.

Association between serum uric acid level and components of the metabolic syndrome

BACKGROUND

Serum uric acid (UA) level has been suggested to be associated with factors that contribute to the metabolic syndrome. However, the association between metabolic syndrome and UA has not been elucidated. We sought to determine the association between serum UA level and the number of components that contribute to the metabolic syndrome, and which component was associated most with higher serum UA level.

METHODS

A consecutive sample was taken of the health examinations of all hospital staff who were assessed between January 2004 and December 2004 in a medical center. A total of 3,065 subjects aged 18 to 81 years (635 males, 2,430 females) participated. Blood tests and all physical variables were examined using standard methods. Subjects were divided into 5 groups according to their possession of 0, 1, 2, 3 or > or = 4 components of the metabolic syndrome. The differences in all variables between groups were analyzed by ANOVA. The relationship between serum UA level and the number of metabolic components was determined by linear regression analysis. The contribution to elevated UA of possessing different risk factors was determined by a multivariate linear regression model.

RESULTS

Mean serum UA level increased as the number of metabolic factors increased. Serum UA level was higher in subjects with abnormal triglyceride (TG), waist circumference, high-density lipoprotein cholesterol (HDL-C) level and blood pressure (BP),with mean increases in UA level of 22.8, 21.4, 14.4 and 9.4 micromol/L, respectively (p < or = 0.001), compared to subjects with normal levels. After controlling for body mass index, abnormal TG, HDL-C and BP continued to account, in order of influence, for elevated UA.

CONCLUSION

Serum UA level was elevated significantly as the number of metabolic components increased. Abnormal TG had the most influence on serum UA. A prospective study is warranted to determine if the prevention or treatment of hyperuricemia affects the development of metabolic syndrome.

Elevated serum uric acid levels in metabolic syndrome: an active component or an innocent bystander?

Elevated serum uric acid (SUA) levels are commonly seen in patients with the metabolic syndrome (MetS). Several mechanisms, both direct and indirect, connect the increased SUA levels with the established diagnostic criteria of MetS. It is possible that the increased cardiovascular disease risk associated with the MetS is partially attributed to elevated circulating SUA concentration. Several drugs used in the treatment of MetS may alter SUA levels. Thus, lifestyle measures together with the judicious selection of drugs for the treatment of hypertension, dyslipidemia, and insulin resistance associated with MetS may result in a reduction of SUA levels and possibly cardiovascular disease risk. This review summarizes the pathophysiologic association between SUA and MetS and focuses on the prevention of hyperuricemia and its cardiovascular consequences.

Association of methylenetetrahydrofolate reductase (C677T) polymorphism with hyperuricemia

BACKGROUND AND AIMS

Homozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate reductase (C677T) has been suggested to be positively associated with the risk of vascular disease and neural tube defects. In addition, recent studies have suggested that elevated serum uric acid predicts ischemic heart disease, and epidemiological data on ethnic groups have suggested that genetic factors are determinants of serum uric acid levels. In this study, we tested the hypothesis that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism may be associated with hyperuricemia.

METHODS AND RESULTS

Samples from 518 healthy individuals (268 men and 250 women) were analyzed for MTHFR genotyping and serum uric acid. The participants were categorized to homozygous wild type (CC), heterozygous for wild type and thermolabile (CT), or homozygous for the thermolabile (TT) variant. Serum uric acid was significantly higher in males and females with TT genotype than those with either CC or CT genotype (p=0.0001, ANOVA). Univariate and multivariate analysis showed that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism was a strong correlate and predictor of uric acid in males (r=0.28, p=0.0001, beta=0.673, p=<0.001) and in females (r=0.27, p=0.0001, beta=0.599, p=<0.001). Odds ratio analysis has also shown that the risk of hyperuricemia was greater in males (OR 3.1, CI 1.8-5.2, p=0.001) and females (OR 3.3, CI 1.9-5.7, p=<0.001) with CT genotypes and in males (OR 3.7, CI 1.3-10.7, p=0.014) and females (OR 3.2, CI 1.1-9.7, p=0.032) with TT genotypes than in those with CC genotypes.

CONCLUSION

Results from this study suggest that mutation of 5-MTHFR C677T contributes to the higher uric acid levels in both males and females and may be a risk factor for hyperuricemia.

Alcohol consumption as a trigger of recurrent gout attacks

BACKGROUND

Alcohol consumption has long been considered a trigger for recurrent gout attacks; however, this hypothesis has not been formally tested.

METHODS

We conducted an Internet-based case-crossover study to assess several putative risk factors, including alcohol consumption, thought to trigger recurrent gout attacks. Subjects who had an attack within the past year were recruited online and asked to provide access to medical records pertaining to their gout. Data were obtained on the amount and type of alcoholic beverage consumed on each day over the 2-day period before a gout attack and on each day over a 2-day period during the intercritical period. We examined the amount and type of alcohol consumption and the risk of recurrent gout attacks using a conditional logistic regression adjusting for diuretic use and purine intake.

RESULTS

A total of 197 subjects were recruited online over a 10-month period. Of those, 179 (91%) fulfilled the American College of Rheumatology Criteria for gout. Compared with no alcohol consumption, odds ratios for recurrent gout attacks were 1.1, 0.9, 2.0, and 2.5 for 1 to 2, 3 to 4, 5 to 6, and 7 or more drinks consumed over the 2-day period, respectively (P<.005). A dose-response relationship of risk of gout attacks was more evident for alcohol consumed over the last 24 hours. An increased risk of recurrent gout attacks was found for each type of beverage consumed.

CONCLUSION

Alcohol consumption triggers recurrent gout attacks. This effect was likely to occur within 24 hours after its consumption.

Effect of fenofibrate in combination with urate lowering agents in patients with gout

BACKGROUND

To assess the efficacy of fenofibrate treatment in combination with urate lowering agents in patients with gout.

METHODS

Fourteen male patients with chronic tophaceous or recurrent acute attacks of gout were evaluated in an open-label pilot study of the hypolipidemic agent, fenofibrate (Lipidil Supra 160 mg/d). Patients were stable on urate lowering agents (allopurinol or benzbromarone) for > or = three months without acute attack for the most recent one month before participating. All patients were being treated with established doses of urate lowering agents without modification throughout the study. Clinical and biochemical assessments including serum uric acid, creatinine, liver function test and fasting serum lipid were measured at (1) baseline (2) after two months of fenofibrate treatment and (3) two months after fenofibrate was withdrawn.

RESULTS

Serum uric acid was lowered by 23% after two months of fenofibrate treatment (6.93 +/- 2.16 vs. 5.22 +/- 1.16 mg/dL; p = 0.016). Triglyceride levels were also reduced after fenofibrate treatment (p = 0.001). However, this effect was reversed after the withdrawal (p = 0.002) of the drug. Alkaline phosphatase was reduced after fenofibrate treatment (p = 0.006), but increased 21% after the withdrawal of the drug (p = 0.002). By contrast, serum levels of high density lipoprotein and creatinine were increased 9% (p = 0.018) and 12% (p = 0.006), respectively; however, both levels were significantly decreased to the baseline levels upon withdrawal of fenofibrate.

CONCLUSIONS

Fenofibrate can effectively reduce uric acid levels in addition to its known hypolipidemic effect. Fenofibrate may be used as a potential urate lowering agent in patients with gout, especially in those with coexisting hyperlipidemia.

New developments in the epidemiology and genetics of gout

The prevalence of gout appears to be rapidly increasing worldwide and is no longer a disorder suffered primarily by over-fed alcohol consumers. Emerging risk factors include longevity, metabolic syndrome, and new classes of pharmacologic agents. In some ethnic populations, no obvious risk factors can explain the high incidence of hyperuricemia and gout, suggesting a genetic liability. Studies to identify genes associated with gout have included families with defects in purine metabolism, as well as families in whom the occurrence of gout is secondary to renal disorders such as juvenile hyperuricemic nephropathy and medullary cystic kidney disease. Case-control studies of isolated aboriginal cohorts suffering from primary gout have revealed several chromosomal loci that may harbor genes that are important to the development and/or progression of gout.

Prevalence of hyperuricemia and relation of serum uric acid with cardiovascular risk factors in a developing country

BACKGROUND

The prevalence of hyperuricemia has rarely been investigated in developing countries. The purpose of the present study was to investigate the prevalence of hyperuricemia and the association between uric acid levels and the various cardiovascular risk factors in a developing country with high average blood pressures (the Seychelles, Indian Ocean, population mainly of African origin).

METHODS

This cross-sectional health examination survey was based on a population random sample from the Seychelles. It included 1011 subjects aged 25 to 64 years. Blood pressure (BP), body mass index (BMI), waist circumference, waist-to-hip ratio, total and HDL cholesterol, serum triglycerides and serum uric acid were measured. Data were analyzed using scatterplot smoothing techniques and gender-specific linear regression models.

RESULTS

The prevalence of a serum uric acid level >420 micromol/L in men was 35.2% and the prevalence of a serum uric acid level >360 micromol/L was 8.7% in women. Serum uric acid was strongly related to serum triglycerides in men as well as in women (r = 0.73 in men and r = 0.59 in women, p < 0.001). Uric acid levels were also significantly associated but to a lesser degree with age, BMI, blood pressure, alcohol and the use of antihypertensive therapy. In a regression model, triglycerides, age, BMI, antihypertensive therapy and alcohol consumption accounted for about 50% (R2) of the serum uric acid variations in men as well as in women.

CONCLUSIONS

This study shows that the prevalence of hyperuricemia can be high in a developing country such as the Seychelles. Besides alcohol consumption and the use of antihypertensive therapy, mainly diuretics, serum uric acid is markedly associated with parameters of the metabolic syndrome, in particular serum triglycerides. Considering the growing incidence of obesity and metabolic syndrome worldwide and the potential link between hyperuricemia and cardiovascular complications, more emphasis should be put on the evolving prevalence of hyperuricemia in developing countries.