An allopurinol-controlled, randomized, double-dummy, double-blind, parallel between-group, comparative study of febuxostat (TMX-67), a non-purine-selective inhibitor of xanthine oxidase, in patients with hyperuricemia including those with gout in Japan: phase 3 clinical study.

BACKGROUND: Allopurinol has been widely used for treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat is potentially a safe and efficacious alternative. OBJECTIVES: Febuxostat or allopurinol was administered to patients with hyperuricemia including gout for 8 weeks to compare the efficacy and safety of these drugs. METHODS: Doses of febuxostat and allopurinol were 10 and 100 mg/d, respectively, during a 12-day introduction period and were increased to 40 and 200 mg/d for the subsequent treatment period of 44 days. RESULTS: : The percent changes in serum uric acid levels after 8 weeks were -40.75% for the febuxostat group and -34.41% for the allopurinol group (P < 0.001, analysis of variance, closing testing procedure). The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less after 8 weeks was 82.0% for the febuxostat group and 70.0% for the allopurinol group (P = 0.019, logistic regression analysis). Regarding safety, 213 adverse events were observed in the febuxostat group and 220 events in the allopurinol group. For 10 patients (8.2%) in the febuxostat group and 14 patients (11.6%) in the allopurinol group, association with the study drugs could not be ruled out. There were no severe adverse drug reactions in the febuxostat group other than a high frequency of gout attacks induced by the sudden reduction in blood uric acid levels during the early treatment period. CONCLUSIONS: Febuxostat at 40 mg/d demonstrated more potent hypouricemic effects than allopurinol at 200 mg/d, was efficacious regardless of medical history of gout, and is considered safe for treatment of hyperuricemia.

Multicenter, open-label study of long-term administration of febuxostat (TMX-67) in Japanese patients with hyperuricemia including gout.

BACKGROUND: In previous clinical studies of hyperuricemia including gout, although serum uric acid (sUA) levels reduced to 6.0 mg/dL or less in about 80% of patients treated with 40 mg/d febuxostat, a nonpurine selective xanthine oxidase inhibitor, a few patients did not show this result. OBJECTIVE: The objective of the study was to evaluate the efficacy and safety of long-term febuxostat administration at up to 60 mg/d in patients with hyperuricemia and gout. METHODS: In a 52-week, multicenter, open-label trial, febuxostat was initially administered at 10 mg/d; then, the dosage was increased in a stepwise fashion to 40 mg/d. For sUA levels greater than 6.0 mg/dL at week 10, the dosage was increased to 60 mg/d from week 14 onward (60-mg group), but it was maintained at 40 mg/d until the end of the study for patients with sUA levels 6.0 mg/dL or less at week 10 (40-mg group). RESULTS: The sUA levels in both groups decreased dose dependently. At 52 weeks, 84.5% and 85.0% of the 40- and 60-mg groups, respectively, achieved mean sUA levels 6.0 mg/dL or less. There was no marked difference between the 2 dosage groups in terms of the incidence of adverse events. Furthermore, there were no noteworthy adverse events or adverse drug reactions in the patients with renal dysfunction, and no differences in drug efficacy up to 60 mg/d were noted between the patients with moderate or mild renal dysfunction and those with normal renal function. CONCLUSIONS: Febuxostat seems to be a promising therapeutic drug for gout or hyperuricemia, even in patients with renal dysfunction.

Placebo-controlled, double-blind study of the non-purine-selective xanthine oxidase inhibitor Febuxostat (TMX-67) in patients with hyperuricemia including those with gout in Japan: phase 3 clinical study.

BACKGROUND: : Allopurinol has been widely used for treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative. OBJECTIVES: : A multicenter study with randomized, placebo-controlled, double-blind, parallel-group comparison was carried out to evaluate the efficacy and safety of febuxostat in 103 patients with hyperuricemia (including patients with gout) in Japan. METHODS: : Subjects were treated with febuxostat (20 or 40 mg/d) or a placebo for 8 weeks. The variables evaluated were the percentage of patients achieving serum uric acid levels 6.0 mg/dL or less and the percent change in serum uric acid levels after 8 weeks. RESULTS: : The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less after 8 weeks was 91.2% in the febuxostat 40-mg/d group, 45.7% in the 20-mg/d group, and 0.0% in the placebo group. The percent changes in serum uric acid levels after 8 weeks were -44.9% in the febuxostat 40-mg/d group, -28.9% in the 20-mg/d group, and -0.6% to -0.5% in the placebo group. No severe or medically significant adverse reaction attributable to febuxostat was noted, and there was no event that could pose a clinical problem. The efficacy did not differ depending on the presence/absence of gout history. CONCLUSIONS: : These results suggest that febuxostat (20 or 40 mg/d) is useful as a new means of treating hyperuricemia and is capable of reducing serum uric acid levels to 6.0 mg/dL or less (goal of treatment) with high safety regardless of the presence/absence of gout history.

Placebo-controlled double-blind dose-response study of the non-purine-selective xanthine oxidase inhibitor febuxostat (TMX-67) in patients with hyperuricemia (including gout patients) in japan: late phase 2 clinical study.

BACKGROUND: Allopurinol has been widely used for the treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative. OBJECTIVES: A multicenter study with randomized, placebo-controlled, double-blind, parallel, intergroup comparison was carried out to evaluate the dose-response relationship, efficacy, and safety of febuxostat in 202 patients with hyperuricemia (including patients with gout) in Japan. METHODS: The subjects were treated with febuxostat at fixed maintenance doses (20-80 mg/d) or a placebo for 16 weeks. The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less and the percent change in serum uric acid levels after 16 weeks of treatment were evaluated. RESULTS: The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less at 16 weeks was 87.8% in the 80-mg/d dose group, 83.3% in the 60-mg/d group, 82.9% in the 40-mg/d group, 46.5% in the 20-mg/d group, and 2.6% in the placebo group (P < 0.001, Mantel-Haenszel test). A statistically significant dose-response relationship was found. The percent change in serum uric acid levels after 16 weeks of treatment differed significantly between each febuxostat dose group and the placebo group and increased in a dose-dependent manner above 40 mg/d. No deaths, events posing a clinical problem, or serious adverse reactions attributable to febuxostat were noted. Similar results were obtained regardless of gout history. CONCLUSIONS: Febuxostat can safely reduce serum uric acid levels to 6.0 mg/dL or less in 80% or more of patients with hyperuricemia (including gout) at doses of 40 mg/d or higher.

An allopurinol-controlled, multicenter, randomized, open-label, parallel between-group, comparative study of febuxostat (TMX-67), a non-purine-selective inhibitor of xanthine oxidase, in patients with hyperuricemia including those with gout in Japan: phase 2 exploratory clinical study.

BACKGROUND: Allopurinol has been widely used for the treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative. OBJECTIVES: Febuxostat was administered to patients with hyperuricemia including gout in Japan to compare its efficacy and safety with those of allopurinol. METHODS: The starting dose of febuxostat and allopurinol was 10 and 100 mg/d, respectively, and was increased to the fixed maintenance dose of 40 or 60 mg/d for febuxostat and 300 mg/d for allopurinol for 16 weeks. RESULTS: : The percent change in the serum uric acid level at 16 weeks compared with the baseline serum uric acid level was -42.96% ± 13.33% and -52.47% ± 9.79% for the febuxostat 40- and 60-mg/d groups, respectively, and -36.55% ± 18.59% for the allopurinol group, indicating that the hypouricemic effects of febuxostat increased in a dose-dependent manner and equaled to or surpassed those of allopurinol (P = 0.0239, 2-sample t test). The percentage of patients with serum uric acid levels of 6.0 mg/dL or less at 16 weeks was 88.9% and 100% for the febuxostat 40- and 60-mg/d groups, respectively, and 68.8% for the allopurinol group, showing higher achievements for the febuxostat groups compared with the allopurinol group. All adverse drug reactions were mild to moderate in severity, and there were no severe symptoms or reactions leading to drug discontinuation. CONCLUSIONS: These results suggest that febuxostat is safe at doses of 40 and 60 mg/d and has equal or greater efficacy than 300 mg/d allopurinol.

Involvement of hepatoma-derived growth factor in the growth inhibition of hepatocellular carcinoma cells by vitamin K(2).

BACKGROUND: Vitamin K(2) has been reported to suppress the growth of human hepatocellular carcinoma (HCC) in vitro and hepatocarcinogenesis in hepatitis C virus (HCV)-related cirrhosis in vivo. Hepatoma-derived growth factor (HDGF) is a unique nuclear targeting growth factor that is highly expressed in HCC cells and is a possible prognostic factor for patients with HCC. We investigated the regulation of HDGF expression by vitamin K(2). METHODS: Three HCC-derived cell lines, HepG2, HuH-7, and SK-Hep-1, were used. Cell number was determined with the MTT assay. The expression levels of HDGF mRNA and protein were measured by the real-time reverse transcriptase-polymerase chain reaction (PCR) method and ELISA and Western blot analysis, respectively. The HDGF promoter activity was measured by a dual luciferase-reporter assay. RESULTS: Vitamin K(2) suppressed the growth of the three HCC cell lines in a dose-dependent manner. Vitamin K(2) significantly suppressed the expression of the HDGF protein and mRNA in three cell lines. By a luciferase assay, vitamin K(2) significantly suppressed the promoter activity of the HDGF protein. Based on some luciferase-reporter plasmids containing truncated promoter regions, the possible responsive site of vitamin K(2) seems to reside in the region -1 to -150 bp of the HDGF gene. CONCLUSIONS: These findings suggested that regulation of the HDGF gene expression is one of the crucial mechanisms of vitamin K(2)-induced cell growth suppression for HCC.

Hepatoma-derived growth factor is induced in liver regeneration.

AIM: Hepatoma-derived growth factor (HDGF) is a heparin-binding protein, which has been suggested to be involved in the development of kidneys, the cardiovascular system and the liver. We have shown that HDGF is highly expressed in parenchymal hepatocytes in the developing liver and promotes fetal hepatocyte proliferation. In the present study, we asked whether HDGF expression was related to liver regeneration. METHODS: We examined the mRNA and protein expressions of HDGF in two liver regeneration models. In addition, cellular distribution of HDGF in the regenerating liver was investigated by immunohistochemistry. RESULTS: In the carbon tetrachloride (CCl(4))-treated liver, HDGF expression was induced and the peak was detected at 24 h after the CCl(4 )injection. HDGF expression was also enhanced in the hepatectomy model and the peak was detected at 12 h after surgery. The increased expression of HDGF protein was also confirmed by western blotting. Expression of the HDGF gene in the regenerating liver was dominantly detected in parenchymal hepatocytes. CONCLUSION: These findings showed that HDGF expression was induced in parenchymal hepatocytes before the DNA synthesis in the regenerating liver, suggesting the possible involvement of HDGF in liver regeneration as an autocrine factor.

Triple therapy of initial high-dose interferon with ribavirin and amantadine for patients with chronic hepatitis C.

AIMS: We previously reported the potential effect of combination therapy of an initial high-dose interferon (IFN) and amantadine on the eradication of HCV-RNA in patients with chronic hepatitis C. The additive effects of amantadine on interferon and ribavirin combination therapy remain controversial. In this study we investigated the efficacy of initial high-dose IFN with ribavirin and amantadine on the virological response in patients with chronic hepatitis C with a high viral load of genotype 1b. METHODS: Twenty-two patients with high viral loads of genotype 1b hepatitis C virus were enrolled in this pilot study. Patients were administered IFN-beta for four weeks and then IFN-alpha2b for 22 weeks with daily oral administration of ribavirin and amantadine. RESULTS: A sustained virological response (SVR) was shown in 31.8% (seven of 22 patients). With the naïve patients, the SVR rate was 21.4% (three of 14 patients). In patients who could not eradicate HCV-RNA by previous IFN monotherapy, the SVR rate was 50% (four of eight patients). CONCLUSION: Triple therapy with an initial high dose of IFN with ribavirin and amantadine may be effective, especially for chronic hepatitis C IFN-retreatment patients with a high viral load of genotype 1b.

Vitamin K2 inhibits the proliferation of HepG2 cells by up-regulating the transcription of p21 gene.

AIM: Vitamin K2 has been reported to inhibit the growth of human hepatocellular carcinoma (HCC) in vitro and suppress hepatocarcinogenesis in vivo. However, its inhibitory mechanism has not yet been clarified. METHODS: Different concentrations of vitamin K2 (30, 10, 1, 0.1 and 0.01 muM) were added to the HCC cell line HepG2 to assess effects on cell growth. The effect of vitamin K2 on cell cycle progression was determined by flow-cytometric analysis. The expression of cell cycle regulatory proteins p21 and p27 was then examined by Western blot. Whether vitamin K2 regulates the gene expression through action on the p21 promoter region was investigated by luciferase assay. RESULTS: Vitamin K2 inhibited the growth of HepG2 cells dose-dependently, and its inhibitory rate reached approximately 50% at the dose of 30 muM after 96 h treatment. After treatment with vitamin K2, the proportion of cells in G0-G1 phase increased, and in S phase decreased. Apoptotic cells were not detected. The expression of cell cycle regulatory protein p21 was induced by vitamin K2 treatment, but p27 was not. By the luciferase assay, vitamin K2 significantly activated the promoter of p21. Knock-down of p21 by siRNA reversed the growth inhibition of HepG2 cells by vitamin K2. CONCLUSIONS: The findings suggest that vitamin K2 suppresses the proliferation of HCC cells by blocking the cell cycle G1/S progression through the transcriptional induction of p21.

Hemochromatosis with mutation of the ferroportin 1 (IREG1) gene.

The HFE, H ferritin, TFR2, and ferroportin 1 genes of a Japanese patient diagnosed as having hemochromatosis were amplified by PCR and sequenced. A novel mutation in the ferroportin 1 was found in the patient. It was located in the noncoding region of the ferroportin 1; nucleotide 117 adenine was changed to guanine, 7 nucleotides downstream the iron responsive element (IRE) region. This mutation was not found in the patient's son or daughter, or in 50 healthy individuals. It was suggested that the mutation in the ferroportin 1 may be related to hemochromatosis of this patient.

Hepatoma-derived growth factor induces tumorigenesis in vivo through both direct angiogenic activity and induction of vascular endothelial growth factor.

Hepatoma-derived growth factor (HDGF) is highly expressed in tumor cells, and stimulates their proliferation. In the present study, we investigated the role of HDGF in tumorigenesis and elucidated the mechanism of action. Stable transfectants of NIH3T3 cells overexpressing HDGF did not show significant anchorage-independent growth in soft agar assay. However, these stable transfectants overexpressing HDGF generated sarcomatous tumors in nude mice. These tumors were red-colored macroscopically, and histologically showed a rich vascularity. Immunohistochemical analysis using CD31 antibody showed new vessel formation. Recombinant HDGF stimulated proliferation of human umbilical vein endothelial cells in a dose-dependent manner, and stimulated tubule formation. Furthermore, vascular endothelial growth factor (VEGF) was detected immunohistochemically in the tumor tissues. Transient expression of HDGF induced both VEGF gene and protein expression as demonstrated by a reporter assay using VEGF gene promoter. The administration of anti-VEGF neutralizing antibody significantly suppressed, but did not block, the tumor growth of HDGF-overexpressing cells in nude mice. Thus, these findings suggested that HDGF-induced tumor formation in vivo involves induction of VEGF as well as direct angiogenic activity.

Increased expression of interleukin-18 receptor on T lymphocytes in patients with acute graft-versus-host disease after allogeneic bone marrow transplantation.

Acute graft-versus-host disease (aGVHD), a potentially fatal side effect of allogeneic bone marrow transplantation (BMT), is initiated by the action of donor-derived T lymphocytes. We have shown previously that aGVHD is associated with elevated serum levels of interleukin-18 (IL-18). In this study, we analyzed the expression of the IL-18 receptor (IL-18R) on T lymphocytes of BMT patients with aGVHD. Flow cytometric analysis showed that in healthy subjects, a small population of CD4+ T cells expressed IL-18Ralpha, whereas a relatively large population of CD8+ T cells expressed IL-18Ralpha. In aGVHD patients, there were marked increases in the proportion of CD4+ or CD8+ T cells that express IL-18Ralpha. RT-PCR assays showed elevation of IL-18Ralpha and IL-18Rbeta mRNA levels in CD8+ T cells in aGVHD patients. These findings suggest that the expression of IL-18R is upregulated in T cells in patients with aGVHD and that the IL-18/IL-18R system is active during aGVHD.

Differential upregulation of interleukin-18 receptor alpha chain between CD4+ and CD8+ T cells during acute graft-versus-host disease in mice.

Interleukin-18 (IL-18), a unique cytokine that stimulates both T helper 1 (Th1) and Th2 responses, is associated with acute graft-versus-host disease (aGVHD), the major limiting toxicity following allogeneic stem cell transplantation. Here, we investigated the mechanism underlying the upregulation of IL-18 receptor (IL-18R) expression on T cells in murine aGVHD models. The induction of aGVHD elevated host serum IL-12 levels and increased expression of IL-18Ralpha chain (IL-18Ralpha) on engrafted T cells, in particular on CD8+ T cells. However, IL-18Ralpha expression did not increase on the CD4+ T cells of an IL-12-deficient host, indicating the IL-12-dependent upregulation of IL-18Ralpha expression on CD4+ T cells during aGVHD. Purified donor CD8+ T cells transferred in the host increased IL-18Ralpha expression. In vitro experiments showed that IL-18Ralpha expression upregulated on CD8+ T cells but not on CD4+ T cells on stimulation through the T cell receptor (TCR). These results suggest that IL-18Ralpha expression is differentially upregulated between CD4+ and CD8+ T cells during aGVHD, depending on endogenous IL-12 and TCR engagement, respectively.

Involvement of interleukin-18 in acute graft-versus-host disease in mice.

BACKGROUND: Interleukin (IL)-18 stimulates T helper 1 (Th1)-mediated immune responses and the development of cytotoxic T lymphocytes (CTLs). Antihost CTLs are major effectors in acute graft-versus-host disease (aGvHD), a potentially fatal complication after allogeneic stem-cell transplantation. We investigated the relevant role of IL-18 in the development of aGvHD in mice. METHODS: Irradiated (C57BL/6x DBA/2) F1 (BDF1) mice transplanted with wild-type (WT) C57BL/6 (B6) splenocytes were compared with those transplanted with IL-18Ralpha-deficient B6 splenocytes with respect to Th1 development, CTL activity, severity of aGvHD, and survival. RESULTS: Transplantation of WT B6 spleen cells into BDF1 mice induced aGvHD that was accompanied by elevation of both serum IL-18 levels and IL-18 receptor alpha chain (IL-18Ralpha) expression on engrafted T cells. The transplantation of WT B6 cells also induced high antihost CTL activity in host spleen, whereas transplantation of IL-18Ralpha-deficient B6 cells exhibited significantly reduced antihost-specific CTL activity, indicating that IL-18Ralpha-deficient CTLs were less cytotoxic than IL-18Ralpha-expressing CTLs. Moreover, the hosts receiving transplants with the IL-18Ralpha-deficient B6 cells had fewer fatal tissue injuries and increased their survival rates as compared with those receiving transplants with WT cells. Nevertheless, Th1 development in the hosts was the same, regardless of the type of donor cells. CONCLUSIONS: These results suggest that Th1 induction and baseline CTL activity in aGvHD occur in the absence of IL-18, but endogenous IL-18 further accelerates aGvHD reaction to its full-blown manifestation. Thus, IL-18 may be involved in the development aGvHD by enhancing CTL activity.

Effects of angiotensin II infusion on renal excretion of purine bases and oxypurinol.

The effect of angiotensin II infusion on the renal transport of purine bases and oxypurinol (a metabolite of allopurinol) was investigated in 5 healthy subjects who were orally given allopurinol (300 mg) 9 hours prior to the study. Angiotensin II was intravenously administered at 8 ng/min/kg for 2 hours. The fractional clearances of uric acid, xanthine, and oxypurinol were significantly decreased during angiotensin II infusion; however, that of hypoxanthine did not change. The urinary excretion levels of uric acid, xanthine, and oxypurinol were also significantly decreased during angiotensin II infusion. These results suggest that angiotensin II infusion affected the renal clearances of uric acid, xanthine, and oxypurinol through direct tubular transport and/or hemodynamic changes. Accordingly, the hypouricemic effect of allopurinol may be exaggerated in hypertensive gout patients with an enhanced renin-angiotensin system, since an increased biological half-life of oxypurinol is expected in these patients.

Identification of a new point mutation in the human molybdenum cofactor sulferase gene that is responsible for xanthinuria type II.

A 43-year-old xanthinuric female was referred to our department because of hypouricemia. Routine laboratory data showed hypouricemia, a high level of plasma oxypurines, decreased urinary uric acid excretion, and increased urinary oxypurine excretion, with xanthine dehydrogenase activity in the duodenal mucosa below the limits of detection. In addition, allopurinol was not metabolized. From these findings, the patient was diagnosed with xanthinuria type II. To investigate the properties of xanthine dehydrogenase/xanthine oxidase (XDH/XO) deficiency, a cDNA sequence encoding XDH/XO, aldehyde oxidase (AO), and molybdenum cofactor sulferase (MCS), as well as immunoblotting analysis for XDH/XO protein, obtained from duodenal mucosa samples were performed. The XDH/XO cDNA and AO cDNA sequences of the xanthinuric patient were consistent with previously reported ones, whereas the MCS cDNA sequence revealed a point mutation of G to C in nucleotide 466, which changed codon 156 from GCC (Ala) to CCC (Pro). In addition, the MCS genomic DNA sequence including the site of the mutation revealed the same, suggesting that the xanthinuric patient was homozygous for this mutation. Such findings have not been previously reported for patients with xanthinuria type II.

Effect of beer on the plasma concentrations of uridine and purine bases.

We conducted the present study to determine whether beer, both with and without ethanol content, increases the plasma concentration and urinary excretion of purine bases and uridine. Because 10 mL of regular beer (with ethanol) was found to contain 0.34 g of freeze-dried beer (without ethanol) and 0.5 mg of uridine, 5 healthy males were given regular beer (10 mL/kg of body weight) and freeze-dried beer (0.34 g/kg of body weight) or uridine (0.5 mg/kg of body weight). The plasma concentrations of hypoxanthine, xanthine, and uridine increased by 3.5-fold (P <.05), 4.7-fold (P <.05), and 1.8-fold (P <.05), respectively, 30 minutes after regular beer ingestion, and the urinary excretion of hypoxanthine, xanthine, and uridine increased by 4.0-fold (P <.05), 4.5-fold (P <.01), and 1.7-fold (P <.05), respectively, when measured 1 hour after ingestion. The plasma concentrations of uric acid and total purine bases increased by 6.5% (P <.05) and 7.6% (P <.05), respectively, 30 minutes after regular beer ingestion, whereas the urinary excretion of uric acid did not increase, while that of total purine bases increased by 1.3-fold (P <.05) when measured 1 hour after ingestion. As for freeze-dried beer, the plasma concentrations of uric acid total purine bases increased by 4.4% (P <.05) and 4.6% (P <.05), respectively, and that of uridine by 1.5-fold (P <.01) 30 minutes after ingestion, while the urinary excretion of uridine increased by 1.4-fold (P <.01) 1 hour after ingestion. However, the plasma concentrations and urinary excretion of hypoxanthine and xanthine and the urinary excretion of uric acid and total purine bases did not change significantly. As for uridine ingestion, the plasma concentration of uridine increased by 1.37-fold (P <.01) 30 minutes after ingestion, and the urinary excretion of uridine increased by 1.3-fold (P <.01) 1 hour after ingestion. However, the plasma concentrations and urinary excretion of hypoxanthine, xanthine, uric acid, and total purine bases did not change significantly. These results suggest that the purines in beer played a major role in the increase in the plasma concentration of uric acid, while both uridine and ethanol in beer had a significant effect on the increase in plasma concentration of uridine.

Effect of inosine on the plasma concentration of uridine and purine bases.

To examine whether inosine increases the plasma concentration of uridine, 20 mg/kg body weight of inosine was orally administered to 5 healthy subjects. The plasma concentration of uridine was increased by 1.25-fold (P <.05), while that of hypoxanthine, xanthine, and uric acid was increased by 1.26-fold (P <.01), 1.26-fold (P <.01), and 1.2-fold (P <.05), respectively, 2.5 hours after the oral administration of inosine. In addition, the 1-hour urinary excretion of uridine was increased by 1.17-fold (P <.05) and that of hypoxanthine, xanthine, and uric acid by 1.38-fold (P <.05), 1.4-fold (P <.05), and 1.4-fold (P <.05) between 2 and 3 hours after the administration of inosine. We also conducted an in vitro study with Mahlavu cells and found that the addition of inosine (50 micromol/L) inhibited a decrease in the concentration of uridine in medium originally containing 50 micromol/L uridine. Further, we demonstrated that the apparent Km and Vmax values for Na-independent uridine transport were 67.0 +/- 4.3 micromol/L and 7.0 +/- 0.3 pmol/mg protein/s, respectively, and the Ki value of inosine for Na-independent uridine transport was 45.1 +/- 12.1 micromol/L. These results suggest that inosine inhibits uridine uptake via the nucleoside transport pathway, and administered inosine is converted to purine bases (uric acid, hypoxanthine, and xanthine) in the intestine and liver, before entering the systemic circulation via the hepatic vein.

Elevated levels of interleukin-18 and tumor necrosis factor-alpha in serum of patients with type 2 diabetes mellitus: relationship with diabetic nephropathy.

To compare levels of interleukin (IL)-18, tumor necrosis factor-alpha (TNF-alpha), and IL-6 in serum, we studied 151 type 2 diabetes mellitus patients with various degrees of nephropathy, as well as 80 healthy volunteers. IL-18, TNF-alpha, and IL-6 in serum were measured using an enzyme-linked immunosorbent assay (ELISA) with the respective mouse monoclonal antibodies. Significant differences in serum levels of IL-18 and TNF-alpha were observed between the patients and control subjects (IL-18, 278.0 +/- 11.9 pg/mL v 172.8 +/- 7.7 pg/mL, P <.0001; TNF-alpha, 2.41 +/- 0.18 pg/mL v 0.46 +/- 0.18 pg/mL, P <.0001), whereas that of IL-6 was not different between the two groups (0.73 +/- 0.10 pg/mL v 0.65 +/- 0.08 pg/mL, difference not significant [NS]), although patients with nephropathy showed higher levels. In addition, IL-18 levels were increased in diabetic patients with the development of urinary albumin excretion, with the highest found in those with microalbuminuria (<30 micro g/mg creatinine, 252.7 +/- 16.4 pg/mL; 30 to >300 micro g/mg creatinine, 352.7 +/- 35.2 pg/mL; >>300 micro g/mg creatinine, 350.0 +/- 16.0 pg/mL). Similarly, TNF-alpha and IL-6 in diabetic patients with microalbuminuria or clinical albuminuria were significantly increased as compared with those without albuminuria (TNF-alpha, 3.20 +/- 0.41 pg/mL v 1.94 +/- 0.18 pg/mL; IL-6, 1.64 +/- 1.11 pg/mL v 0.51 +/- 0.05 pg/mL, P <.05, respectively). These results suggest that serum levels of IL-18, TNF-alpha, and IL-6 may have some etiopathogenic roles in diabetic nephropathy.

Identification of a new point mutation in hypoxanthine phosphoribosyl transferase responsible for hyperuricemia in a female patient.

A 29-year-old woman was referred to our department because of gout. Routine laboratory data showed hyperuricemia, a high level of plasma oxypurines, increased urinary uric acid excretion, and increased urinary oxypurine excretion, with decreased hypoxanthine phosphoribosyl transferase (HPRT) activity in the erythrocytes. From these findings, the patient was diagnosed with a partial deficiency of HPRT. To determine its properties, a cDNA sequence encoding HPRT and the androgen receptor AR XIST minimal promoter gene, as well as methylation of the AR gene were investigated. The HPRT cDNA sequence revealed a point mutation of G to A in nucleotide 40, which changed codon 14 from GAA (Glu) to AAA (Lys) in the mutant gene. In addition, the HPRT genomic DNA sequence, including the mutation site, revealed the same point mutation, indicating that the patient was heterozygote. Further analysis of the AR gene on the X chromosome suggested nonrandom X-chromosome inactivation, whereas the AR XIST minimal promoter gene was normal. Such results have not been previously reported in a female with partial HPRT deficiency.