Uric acid (UA) forms monosodium urate (MSU) crystals to exert proinflammatory actions, thus causing gout arthritis, urolithiasis, kidney disease, and cardiovascular disease. UA is also one of the most potent antioxidants that suppresses oxidative stress. Hyper andhypouricemia are caused by genetic mutations or polymorphism. Hyperuricemia increases urinary UA concentration and is frequently associated with urolithiasis, which is augmented by low urinary pH. Renal hypouricemia (RHU) is associated with renal stones by increased level of urinary UA, which correlates with the impaired tubular reabsorption of UA. Hyperuricemia causes gout nephropathy, characterized by renal interstitium and tubular damage because MSU precipitates in the tubules. RHU is also frequently associated with tubular damage with elevated urinary beta2-microglobulin due to increased urinary UA concentration, which is related to impaired tubular UA reabsorption through URAT1. Hyperuricemia could induce renal arteriopathy and reduce renal blood flow, while increasing urinary albumin excretion, which is correlated with plasma xanthine oxidoreductase (XOR) activity. RHU is associated with exercise-induced kidney injury, since low levels of SUA could induce the vasoconstriction of the kidney and the enhanced urinary UA excretion could form intratubular precipitation. A U-shaped association of SUA with organ damage is observed in patients with kidney diseases related to impaired endothelial function. Under hyperuricemia, intracellular UA, MSU crystals, and XOR could reduce NO and activate several proinflammatory signals, impairing endothelial functions. Under hypouricemia, the genetic and pharmacological depletion of UA could impair the NO-dependent and independent endothelial functions, suggesting that RHU and secondary hypouricemia might be a risk factor for the loss of kidney functions. In order to protect kidney functions in hyperuricemic patients, the use of urate lowering agents could be recommended to target SUA below 6 mg/dL. In order to protect the kidney functions in RHU patients, hydration and urinary alkalization may be recommended, and in some cases an XOR inhibitor might be recommended in order to reduce oxidative stress.

Heart failure (HF) patients living in rural areas have a lack of HF knowledge and poor self-care because of limited medical care access. Multidisciplinary education to improve self-care behavior is indispensable for such patients. The present study evaluated whether intensive inpatient education improved outcomes of hospitalized HF patients in a Japanese rural setting. An inpatient HF management program based on multidisciplinary team intervention was applied to hospitalized HF patients in a Japanese rural area. We defined patients treated within the program from May 2009 to April 2011 as the intervention group (n = 144), and those treated with the usual care from May 2006 to April 2009 as the usual care group (n = 133). The composite endpoints of HF hospitalization and all-cause mortality were compared between the two groups. Compared with patients in the usual care group, those in the intervention group more often received the optimal interventions such as discharge use of β-blockers, cardiac rehabilitation, pre-discharge diagnostic tests, and multidisciplinary intensive education including nurse-led patient education, pharmacist’s medication teaching, and dietitian’s nutritional guidance (all P < 0.05). The incidence of the composite endpoints significantly decreased after introducing the program (P < 0.001). Among a number of interventions, multidisciplinary intensive education was the most effective intervention to improve the primary outcome (P < 0.001). Multidisciplinary intensive education is a key strategy for helping improve the outcome for Japanese HF patients in a rural setting. Our data may give a positive impact on the improvement of healthcare system in Japan.

Aims: The kidney becomes atrophic in advanced chronic kidney disease, and renal size and parenchymal volume correlate with renal function. However, alterations in renal parenchymal volume have not been adequately studied in terms of the renal cortex and medulla. We investigated the relationship between the changes in the renal cortex and medulla and renal function. Methods: Renal ultrasound (US) parameters including renal length, parenchymal thickness, cortical thickness and medullary thickness were assessed in 176 subjects, who were categorized into 4 groups based on the estimated glomerular filtration rate (ml/min/1.73 m²): group 1, ≥90; group 2, ≥60 but <90; group 3, ≥30 but <60; and group 4, <30. Renal US parameters in both kidneys were compared among the 4 groups. Results: We found stepwise associations in renal length, cortical thickness and parenchymal thickness with decreased renal function. Medullary thickness showed no changes among groups 1-3. Multiple linear regression analysis including sex, age and renal US parameters showed that only renal length was an independent predictor of renal function. When analyzed in groups 1-3, cortical thickness was the strongest associated parameter. Lower cortical left/right ratio (left cortical thickness/right cortical thickness) showed a stepwise association with a decrease in renal function. Conclusion: Renal length and cortical thickness measured by US were correlated with renal function. In particular, left cortical thickness could help to detect early changes in renal function.

Background：When macrophages are primed by lipopolysaccharides, mono sodium urate (MSU) crystals activate NLRP3 inflammasomes and promote IL-1β and IL-18 production after phagocytosis of MSU. It was previously reported that anti-IL-1β antibodies suppress symptoms of gout and the occurrence of cardiovascular disease. Thus, inhibition of NLRP3 inflammasomes, which produce IL-1β and IL-18, may be a novel therapeutic strategy against these diseases. Purpose：To reveal the effects of dotinurad, a selective urate reabsorption inhibitor, and other uric acid lowering agents on MSU crystal-induced activation of NLRP3 inflammasomes in macrophages. Methods：Activity of NLRP3 inflammasomes in J774 mouse macrophages was evaluated by quantifying secreted caspase-1 and IL-1β using a western blot and ELISA in both the absence and presence of dotinurad or other uric acid lowering agents. Results：MSU increased protein levels of caspase-1 and IL-1β. This effect was inhibited by a clinical concentration of dotinurad. Neither febuxostat nor allopurinol influenced the levels of caspase-1 and IL-1β, whereas benzbromarone decreased their levels. The inhibitory effects of dotinurad and other uric acid lowering agents on secretions of IL-1β from the macrophages were confirmed by ELISA. Conclusion：Dotinurad, a selective urate reabsorption inhibitor, suppresses MSU-induced activation of NLRP3 inflammasomes in macrophages.

Background: Extremely low uric acid (UA) levels or increased urinary UA (Uua) excretion might be risk factors for kidney disease in renal hypouricemia (RHU) patients, but their relationship with kidney dysfunction is unclear. This study investigated time-dependent changes in eGFR in RHU patients. Methods: This multicenter retrospective study assessed UA metabolism and changes in eGFR (median 5.5 years) in 13 RHU patients. We then compared eGFR change in 7 of 13 RHU patients whose eGFR could be measured for 4 years with those in normouricemic group (n = 31). In addition, 7 RHU patients were divided into two groups based on URAT1 gene mutations: homozygote and compound heterozygote mutations (Homo/Com group, n = 3), and wild-type and heterogeneous mutations (WT/Hetero group, n = 4). Results: In 13 RHU patients, the median and mean serum UA (SUA) were 0.8 (0.4–2.5) and 1.1 ± 0.7 mg/dL. The median and mean Uua were 44.3 (12.7–141.1) and 49.7 ± 36.2 mg/dL. The median and mean urinary urate clearance (Cua/Ccr) were 46.8 (11.3–73.6) and 43.3 ± 19.7%. Over 4 years, eGFR did not change in the RHU group but declined in the normouricemic group. Annual mean eGFR decline and change rate in the RHU group were the same as those in the normouricemic group (− 1.09 ± 1.11 vs. − 1.09 ± 1.92 mL/min/1.73 m²/year, p = 0.996) (− 1.74 ± 1.96 vs. − 1.36 ± 2.10%, p = 0.664). And no significant difference was found in eGFR decline or change rate between Homo/Com and WT/Hetero groups (− 0.33 ± 1.03 vs. − 1.67 ± 0.85 mL/min/1.73 m²/year, p = 0.116) (− 0.61 ± 1.62 vs. − 2.59 ± 1.91%, p = 0.210). Conclusion: RHU from URAT1 genetic mutation may not show eGFR decline over 4 consecutive years.

BackgroundDiuretics are essential for treating acute decompensated heart failure (ADHF), but the response is inconsistent. This study aimed to clarify whether kidney volume as assessed by ultrasound (US) predicts diuretic resistance in patients with ADHF. MethodsWe enrolled 29 patients with ADHF and 32 controls. Height-adjusted kidney volume was assessed by US. We divided patients into two groups based on the median value of total daily use of furosemide (intravenous dose plus 0.5 × oral dose of furosemide equivalents) during 3 days from admission. Results Patients with ADHF had a significantly smaller left kidney volume than did control subjects (27.7 ± 10.0 vs. 32.8 ± 8.8 mL/m, P < 0.05). Patients in the high-dose furosemide group (≥ 51.7 mg/d) had a significantly lower estimated glomerular filtration rate (eGFR) and a significantly smaller kidney volume than did those in the low-dose furosemide group (eGFR: 43.9 ± 20.4 vs. 60.8 ± 21.6 mL/min/1.73 m2, left kidney volume: 23.2 ± 5.2 vs. 32.6 ± 11.0 mL/m, right kidney volume: 26.5 ± 7.5 vs. 32.6 ± 7.9 mL/m, all P < 0.05). Multivariate logistic analysis showed that left kidney volume, but not eGFR, was independently associated with the requirement of high-dose furosemide (odds ratio: 0.856, 95% confidence interval: 0.735–0.997, P < 0.05). ConclusionKidney volume as assessed by US is a useful predictor of diuretic resistance in patients with ADHF.