Biomedical subjects

Takashi Usui

Publications and source records attributed to Takashi Usui.

At least 19 recordsLinked to original sources

PubMed2007

Inhibitory potential of nonsteroidal anti-inflammatory drugs on UDP-glucuronosyltransferase 2B7 in human liver microsomes.

OBJECTIVE: A number of nonsteroidal anti-inflammatory drugs (NSAIDs) are subject to glucuronidation in humans, and UDP-glucuronosyltransferase (UGT) 2B7 is involved in the glucuronidation of many NSAIDs. The objective of this study was to identify a NSAID with potent inhibitory potential against UGT2B7 using liquid chromatography with tandem mass spectrometry (LC-MS/MS). METHODS: A rapid screening method for detecting the inhibitory potential of various drugs against UGT2B7 was established using a LC-MS/MS system. The effects of nine NSAIDs (acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, mefenamic acid, naproxen, niflumic acid, and salicylic acid) against UGT2B7-catalyzed 3'-azido-3'-deoxythymidine glucuronidation (AZTG) were investigated in human liver microsomes (HLM) and recombinant human UGT2B7. RESULTS: Mefenamic acid inhibited AZTG most potently, with an IC(50) value of 0.3 microM, and its inhibition type was not competitive. The IC(50) values for diclofenac, diflunisal, indomethacin, ketoprofen, naproxen, and niflumic acid against AZTG were 6.8, 178, 51, 40, 23, and 83 microM, respectively, while those for acetaminophen and salicylic acid were >100 microM. The IC(50) values for NSAIDs against AZTG in recombinant human UGT2B7 were similar to those obtained in HLM. CONCLUSION: The method established in this study is useful for identifying drugs with inhibitory potential against human UGT2B7. Among the nine NSAIDs investigated, mefenamic acid had the strongest inhibitory effect on UGT2B7-catalyzed AZTG in HLM. Thus, caution might be exercised when mefenamic acid is coadministered with drugs possessing UGT2B7 as a main elimination pathway.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2007

Effects of bosentan, an endothelin receptor antagonist, on bile salt export pump and multidrug resistance-associated protein 2.

The bile salt export pump (BSEP/Bsep/ABCB11) and multidrug resistance-associated protein 2 (MRP2/Mrp2/ABCC2) are involved in bile acid-dependent and -independent bile secretion, respectively. It has been reported that bosentan, an endothelin receptor antagonist, inhibits Bsep, which may lead to cholestatic liver injury due to the intracellular accumulation of bile salts, while increasing bile salt-independent bile flow. Thus, in this study, the effects of bosentan on BSEP/Bsep and MRP2/Mrp2 were evaluated using membrane vesicles derived from Spodoptera frugiperda (Sf) 9 cells, which express these transporters. The adenosine 5'-triphosphate (ATP)-dependent uptake of (3)H-taurocholic acid into membrane vesicles for BSEP/Bsep was inhibited by bosentan, and its IC(50) values were 76.8 and 101 microM for BSEP and Bsep, respectively. In contrast, bosentan stimulated the MRP2/Mrp2-mediated ATP-dependent vesicular transport of (3)H-estradiol 17beta-glucuronide by shifting the sigmoidal dependence of transport rate on substrate concentration to a more hyperbolic one. Collectively, these results suggest that bosentan inhibits BSEP in humans with a similar potency to rats, and that increased bile salt-independent flow in rats by bosentan is at least partly attributable to the activation of Mrp2.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2006

Identification of human UDP-glucuronosyltransferase responsible for the glucuronidation of niflumic acid in human liver.

PURPOSE: To assess the uridine diphosphate (UDP)-glucuronosyltransferase (UGT) isozymes involved in the glucuronidation of niflumic acid in human liver. METHODS: The glucuronidation activity of niflumic acid was determined in liver microsomes and recombinant UGT isozymes by incubation of niflumic acid with UDP-glucuronic acid (UDPGA). RESULTS: Incubation of niflumic acid with liver microsomes and UDPGA produced one peak, which was identified as a glucuronide from mass spectrometric analysis. A study involving a panel of recombinant human UGT isozymes showed that glucuronidation activity was highest in UGT1A1 among the isozymes investigated. The glucuronidation in human liver microsomes (HLMs) followed Michaelis-Menten kinetics with a Km value of 16 microM, which is similar to that found with recombinant UGT1A1. The glucuronidation activity of niflumic acid in microsomes from eight human livers significantly correlated with UGT1A1-catalyzed estradiol 3beta-glucuronidation activity (r=0.78, p<0.05). Beta-estradiol inhibited niflumic acid glucuronidation with an IC50 of 25 microM in HLMs, comparable to that for UGT1A1. CONCLUSIONS: These findings indicate that UGT1A1 is the main isozyme involved in the glucuronidation of niflumic acid in the human liver.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2006

T-bet regulates Th1 responses through essential effects on GATA-3 function rather than on IFNG gene acetylation and transcription.

T helper type 1 (Th1) development is facilitated by interrelated changes in key intracellular factors, particularly signal transducer and activator of transcription (STAT)4, T-bet, and GATA-3. Here we show that CD4+ cells from T-bet-/- mice are skewed toward Th2 differentiation by high endogenous GATA-3 levels but exhibit virtually normal Th1 differentiation provided that GATA-3 levels are regulated at an early stage by anti-interleukin (IL)-4 blockade of IL-4 receptor (R) signaling. In addition, under these conditions, Th1 cells from T-bet-/- mice manifest IFNG promotor accessibility as detected by histone acetylation and deoxyribonuclease I hypersensitivity. In related studies, we show that the negative effect of GATA-3 on Th1 differentiation in T-bet-/- cells arises from its ability to suppress STAT4 levels, because if this is prevented by a STAT4-expressing retrovirus, normal Th1 differentiation is observed. Finally, we show that retroviral T-bet expression in developing and established Th2 cells leads to down-regulation of GATA-3 levels. These findings lead to a model of T cell differentiation that holds that naive T cells tend toward Th2 differentiation through induction of GATA-3 and subsequent down-regulation of STAT4/IL-12Rbeta2 chain unless GATA-3 levels or function is regulated by T-bet. Thus, the principal function of T-bet in developing Th1 cells is to negatively regulate GATA-3 rather than to positively regulate the IFNG gene.

Acetylation↗

PubMed2006

In vitro inhibitory effects of non-steroidal anti-inflammatory drugs on 4-methylumbelliferone glucuronidation in recombinant human UDP-glucuronosyltransferase 1A9--potent inhibition by niflumic acid.

The inhibitory potencies of non-steroidal anti-inflammatory drugs (NSAIDs) on UDP-glucuronosyltransferase (UGT) 1A9 activity were investigated in recombinant human UGT1A9 using 4-methylumbelliferone (4-MU) as a substrate for glucuronidation. 4-MU glucuronidation (4-MUG) showed Michaelis-Menten kinetics with a Km value of 6.7 microM. The inhibitory effects of the following seven NSAIDs were investigated: acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, naproxen and niflumic acid. Niflumic acid had the most potent inhibitory effect on 4-MUG with an IC50 value of 0.0341 microM. The IC50 values of diflunisal, diclofenac and indomethacin were 1.31, 24.2, and 34.1 microM, respectively, while acetaminophen, ketoprofen and naproxen showed less potent inhibition. Niflumic acid, diflunisal, diclofenac and indomethacin inhibited 4-MUG competitively with Ki values of 0.0275, 0.710, 53.3 and 69.9 microM, respectively, being similar to each IC50 value. In conclusion, of the seven NSAIDs investigated, niflumic acid was the most potent inhibitor of recombinant UGT1A9 via 4-MUG in a competitive manner.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2006

In vitro drug interaction between diflunisal and indomethacin via glucuronidation in humans.

It was reported that the plasma concentration of indomethacin was increased with concomitant oral dosages of diflunisal in humans. Both indomethacin and diflunisal are glucuronidated in humans. The effects of diflunisal on the indomethacin glucuronidation were thus investigated in vitro using human liver microsomes (HLM) and human intestine microsomes (HIM) in order to assess the drug-drug interaction. The glucuronidation of indomethacin in HLM showed atypical kinetics with Km and Ksi values of 210 and 89.5 microM, respectively, while HIM exhibited Michaelis-Menten kinetics with a Km value of 17.4 microM. Diflunisal inhibited the indomethacin glucuronidation in HLM with IC50 values ranging from 100 to 231 microM. In HIM, inhibition of the indomethacin glucuronidation by diflunisal was more potent with IC50 values of 15.2-48.7 microM. When the clinical dose of diflunisal (250 mg b.i.d.) is taken into consideration, it is expected that the diflunisal concentration in the intestine would be higher than the IC50 values for indomethacin glucuronidation in the intestine. These findings suggest that the clinical drug-drug interaction between diflunisal and indomethacin may be at least partly attributable to the inhibition of indomethacin glucuronidation by diflunisal in the intestine.

Algorithms↗

PubMed2006

Anti-aminoacyl-tRNA synthetase antibodies in clinical course prediction of interstitial lung disease complicated with idiopathic inflammatory myopathies.

In the treatment of polymyositis and dermatomyositis (PM/DM), the complication of interstitial lung disease (ILD) is an important prognostic factor. It has been reported that autoantibodies against aminoacyl-tRNA synthetases (ARS) are strongly associated with ILD. The aim of this study is to examine the correlation between anti-ARS and the clinical course of ILD. We investigated 41 cases of PM/DM with ILD. The response of ILD to corticosteroids (CS) was determined according to the change in respiratory symptoms, image findings, and pulmonary function between, before and 2 months after the treatment. Anti-ARS (anti-Jo-1, PL-7, PL-12, EJ, OJ and KS) antibodies were screened with the RNA immunoprecipitation assay. In the stratification into ILD-preceding, simultaneous and myopathy-preceding types, anti-ARS antibodies were significantly frequent in the ILD-preceding type (p < 0.05). In the stratification into anti-ARS-positive and negative groups, the response of ILD to CS was significantly better in the positive group (p < 0.05). However, recurrence of ILD was significantly more frequent in the positive group (p < 0.01), and 2 year prognoses of pulmonary function (%VC and %DLCO) were not different between the two groups. In conclusion, screening of anti-ARS may be useful to predict late-onset myopathy in ILD-preceding patients and to predict the clinical course of ILD in PM/DM patients.

Adult↗

PubMed2006

Serum lipoprotein(a) level and clinical coronary stenosis progression in patients with myocardial infarction: re-revascularization rate is high in patients with high-Lp(a).

BACKGROUND: High serum lipoprotein(a) (Lp(a)) levels are associated with coronary artery disease. METHODS AND RESULTS: The serum Lp(a) levels of 130 patients with acute myocardial infarction (AMI) who underwent direct percutaneous coronary intervention were investigated. On the basis of Lp(a) level at 1 month after the onset of AMI, the patients were classified into 2 groups (high-Lp(a) (> or =30 mg/dl) and low-Lp(a) (< 30 mg/dl)) for evaluation of the clinical coronary stenosis progression (CCSP) rate. CCSP is defined as either target lesion revascularization (TLR) or new lesion revascularization (NLR). The CCSP rate was significantly higher in the high-Lp(a) group than in the low-Lp(a) group (65.8% vs 29.3%, p<0.01). In patients who had coronary stents in the acute phase (n=79), the CCSP and NLR rates were significantly higher in the high-Lp(a) group than in the low-Lp(a) group (45.0% vs 20.3%, p<0.05; 35.0% vs 6.8%, p<0.01), but there was no significant difference in TLR rate between the 2 groups (10.0% vs 13.6%, p=0.858). CONCLUSIONS: High serum Lp(a) level is a significant risk factor for CCSP, but does not influence restenosis after stenting.

Adult↗

PubMed2005

In vitro inhibitory effects of non-steroidal antiinflammatory drugs on UDP-glucuronosyltransferase 1A1-catalysed estradiol 3beta-glucuronidation in human liver microsomes.

The inhibitory potencies of non-steroidal antiinflammatory drugs (NSAID) on UDP-glucuronosyltransferase (UGT) 1A1-catalysed estradiol 3beta-glucuronidation (E3G) were investigated in human liver microsomes (HLM). Inhibitory effects of the following seven NSAID were investigated: acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, naproxen and niflumic acid. Niflumic acid had the most potent inhibitory effect on E3G with an IC50 value of 22.2 microM in HLM. The IC50 values of diclofenac, diflunisal, indomethacin for E3G were 60.9, 37.8 and 51.5 microM, respectively, while acetaminophen, ketoprofen and naproxen showed less potent inhibition. Diclofenac inhibited E3G non-competitively with a Ki value of 112 microM in HLM. The IC50 value of diclofenac for 4-methylumbelliferone glucuronidation in recombinant human UGT1A1 was 57.5 microM, similar to that obtained for E3G using HLM. In conclusion, niflumic acid had the most potent inhibitory effects on UGT1A1-catalysed E3G in HLM among seven NSAID investigated.

Acetaminophen↗

PubMed2004

A liquid chromatographic-tandem mass spectrometric method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma.

A sensitive and selective method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma was developed and validated using liquid chromatography-mass spectrometry with electrospray ionization. Plasma samples were pretreated by solid-phase extraction and chromatographed on a C18 column (75 mm x 4.6 mm i.d.) with a mobile phase consisting of 0.1% formic acid-methanol (70:30 (v/v)), and detected using selected reaction monitoring in the positive-ion mode. The lower limit of quantification was 0.4 ng/ml, and good precision and accuracy were achieved. The validated method allowed analysis of samples for the determination of pharmacokinetic profiles of YM466 in rats.

Animals↗

PubMed2004

Absorption, distribution, metabolism and excretion of YM466, a novel factor Xa inhibitor, in rats.

YM466 is a novel factor Xa inhibitor for the treatment of thrombosis. The absorption, distribution, metabolism and excretion of YM466 were investigated in male Fisher rats after a single oral administration. YM466 was absorbed rapidly from all segments of the gastrointestinal tract except the stomach. After oral dosing, the plasma concentration of (14)C-YM466 reached a maximum within 0.5 h, and declined rapidly with an elimination half-life of 0.64 h. The unchanged YM466 accounted for almost all of its radioactivity, suggesting a minimal metabolism in rats. This was also supported by the finding that no metabolites were observed in bile and urine after oral dosing of (14)C-YM466. The distribution of (14)C-YM466 in tissue was evaluated and the liver and kidney were the organs with radioactivity concentrations consistently higher than that of plasma. Cumulative biliary and urinary excretion of radioactivity in bile duct-cannulated rats was 29.5% and 7.6%, respectively, indicating prominent excretion into bile after oral dosing. This was consistent with the finding that 76.1% and 25.2% of radioactivity dosed were excreted to faeces and urine, respectively, after i.v. dosing. These results suggest that YM466 was rapidly absorbed and then subjected to biliary excretion with a minimal metabolism after oral dosing to rats.

Administration, Oral↗

PubMed2004

Effects of beta-estradiol and propofol on the 4-methylumbelliferone glucuronidation in recombinant human UGT isozymes 1A1, 1A8 and 1A9.

The effects of beta-estradiol and propofol on human UGT1A1, 1A8 and 1A9 activities were investigated using 4-methylumbelliferone (4-MU) as a substrate for glucuronidation. The formation of 4-MU glucuronide (4-MUG) from 4-MU, in recombinant human UGT 1A1, 1A8 and 1A9 was determined using HPLC with fluorescence detection. The glucuronidation activity of 4-MU was the highest in UGT1A9 with an apparent K(m) value of 8.3 microM, while that in UGT1A1 and 1A8 was linear to at least 100 microM. beta-estradiol had potent inhibitory effects on UGT1A9 as well as on UGT1A1 with IC(50) values of 2.1 and 7.2 microM, respectively. Propofol inhibited UGT1A9 activity with an IC(50) of 55 microM, while the IC(50) value was much higher for UGT1A8. In contrast, beta-estradiol and propofol activated 4-MU glucuronidation in UGT1A1 and 1A8, respectively. This study therefore indicates that the use of beta-estradiol as a specific inhibitor for UGT1A1 should be used with care in the identification of UGT isozymes responsible for glucuronidation in human liver microsomes.

Cells, Cultured↗

PubMed2004

Simultaneous expression of guinea pig UDP-glucuronosyltransferase 2B21 (UGT2B21) and 2B22 in COS-7 cells enhances UGT2B21-catalyzed chloramphenicol glucuronidation.

Our previous study suggested that hetero-oligomer formation of guinea pig liver UDP-glucuronosyltransferases (UGTs) 2B21 and 2B22 enhances UGT2B21-catalyzed morphine-6-glucuronidation. In this work, further evidence for a functional hetero-oligomer between UGT2B21 and UGT2B22 was provided by studies of the glucuronidation of chloramphenicol with dual expression in COS-7 cells. UGT2B21 expressed in COS cells was capable of glucuronidating the 3-hydroxyl group of morphine, 4-hydroxybiphenyl, borneol, testosterone, androsterone, and estriol, whereas it had some effect on chloramphenicol. On the contrary, UGT2B22 does not exhibit any significant activity toward these typical substrates tested in this study. When UGT2B21 and UGT2B22 were expressed simultaneously, the chloramphenicol glucuronidation was enhanced to 4.5-fold, whereas the activities toward other substrates were little affected except that for the 6-hydroxyl group of morphine. The protein expression level of UGT2B21 was comparable when UGT2B21 was expressed with or without UGT2B22. These results suggest that simultaneous expression of UGT2B21 and UGT2B22 enhances UGT2B21-catalyzed chloramphenicol glucuronidation. Hetero-oligomer formation of UGT2B21 and UGT2B22 may act by fine-tuning the catalytic glucuronidation of chloramphenicol.

Animals↗

PubMed2004

Application of LC-NMR for characterization of rat urinary metabolites of zonampanel monohydrate (YM872).

Zonampanel monohydrate (YM872) has a potent and selective antagonistic effect on the glutamate receptor subtype, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor. Metabolic fingerprinting in rat urine after a single intravenous administration of (14)C-labeled YM872 ((14)C-YM872) revealed the presence of two metabolites, R1 and R2. The two metabolites were semi-purified by preparative HPLC from rat urine after a single intravenous administration of non-labeled YM872, and their structures were elucidated by various instrumental analyses involving LC-NMR. The results showed that R1 and R2 have a hydroxyamino group and an amino group at the C-7 position of the quinoxalinedione skeleton, respectively. Therefore, the proposed metabolic pathway of YM872 in rats involves the reduction of the nitro group to a hydroxyamino group and then subsequent reduction to an amino group.

Animals↗

PubMed2003

Transforming growth factor (TGF)-beta1-producing regulatory T cells induce Smad-mediated interleukin 10 secretion that facilitates coordinated immunoregulatory activity and amelioration of TGF-beta1-mediated fibrosis.

Interleukin (IL)-10 and transforming growth factor (TGF)-beta1 are suppressor cytokines that frequently occur together during a regulatory T cell response. Here we used a one gene doxycycline (Dox)-inducible plasmid encoding TGF-beta1 to analyze this association and test its utility. In initial studies, we showed that intranasal administration of this plasmid (along with Dox) led to the appearance of TGF-beta1-producing cells (in spleen and lamina propria) and the almost concomitant appearance of IL-10-producing cells. Moreover, we showed that these cells exert Dox-regulated suppression of the T helper cell (Th)1-mediated inflammation in trinitrobenzene sulfonic acid colitis. In subsequent in vitro studies using retroviral TGF-beta1 expression, we established that IL-10 production by Th1 cells occurs after exposure to TGF-beta1 from either an endogenous or exogenous source. In addition, using a self-inactivating retrovirus luciferase reporter construct we showed that TGF-beta1 induces Smad4, which then binds to and activates the IL-10 promoter. Furthermore, intranasal TGF-beta1 plasmid administration ameliorates bleomycin-induced fibrosis in wild-type but not IL-10-deficient mice, strongly suggesting that the amelioration is IL-10 dependent and that IL-10 protects mice from TGF-beta1-mediated fibrosis. Taken together, these findings suggest that the induction of IL-10 by TGF-beta1 is not fortuitous, but instead fulfills important requirements of TGF-beta1 function after its secretion by regulatory T cells.

Animals↗

PubMed2003

Acute renal failure due to cholesterol crystal embolism treated with LDL apheresis followed by corticosteroid and candesartan.

Cholesterol crystal embolism (CCE) is caused by the shedding of cholesterol crystals into the bloodstream, and it has been recently recognized as a serious complication after vascular procedures. Our case of CCE, which was diagnosed by skin and renal biopsies, occurred in a patient with hypertension and diabetes mellitus, 3 months after coronary angiography, with the development of renal failure and blue toes. After low-density lipoprotein apheresis (LDL-A), the skin lesions, including livedo reticularis and pain from the acrocyanotic toes, dramatically improved, with partial recovery of renal function. Following the administration of low-dose corticosteroid and candesartan--an angiotensin II type 1 receptor antagonist (ARB)--the eosinophilia disappeared and renal function improved gradually with a decrease in urinary protein excretion. Therefore, a combination therapy of LDL-A, low-dose corticosteroid, and an ARB is a possible treatment for CCE, although the possibility of spontaneous recovery of renal function cannot be eliminated for this patient.

Acute Kidney Injury↗

PubMed2003

GATA-3 suppresses Th1 development by downregulation of Stat4 and not through effects on IL-12Rbeta2 chain or T-bet.

To further understand the interaction among GATA-3, Stat4, and T-bet in helper T cell development, we first showed that retroviral expression of GATA-3 in developing Th1 cells suppresses Th1 development through downregulation of Stat4 rather through downregulation of the IL-12Rbeta2 chain. Correspondingly, Stat4 levels are greatly suppressed during physiological Th2 development. Then, using cells doubly infected with GFP- and YFP-expressing retroviruses, we showed that retroviral GATA-3 expression in developing Th1 cells does not block Th1 development in cells coexpressing Stat4 but does so in cells coexpressing T-bet. Finally, we showed that retroviral Stat4 expression could facilitate Th2-->Th1 conversion in cells bearing an IL-12Rbeta2 transgene, even in cells lacking T-bet. These findings reassert that Stat4 signaling is a central element of Th1/Th2 development.

Animals↗

PubMed2003

Changes in evoked QT intervals according to variations in atrioventricular delay and cardiac function in patients with implanted QT-driven DDDR pacemakers.

In patients with implanted DDD pacemaker, cardiac output is maximal when atrioventricular (AV) delay is set to give the maximum QT interval (QTI). QTI is used as a sensor of a rate-responsive pacemaker and the evoked QTI (eQTI) is measured as the time duration from the ventricular pace-pulse and the T sense point, which is the steepest point of the intracardiac T wave. The relationship between the changes in eQTI according to AV delay variations and cardiac function was studied in 13 patients (74.2+/-9.3 [SD] years old) with an implanted QT-driven DDDR-pacemaker. A special software module was downloaded into the pacemaker memory and a personal computer equipped with the special software was connected to the programmer for eQTI date-logging. AV delay was set at 100, 120, 150, 180 and 210 ms. Delta eQTI was defined as maximal eQTI - minimal eQTI. The ejection fraction (EF) was measured by echocardiography. When the AV delay was prolonged, eQTI gradually increased and reached a peak, and then decreased. Delta eQTI in patients with reduced cardiac function (EF <40%) was significantly greater than that in normal cardiac function (EF >55%, 7.6+/-4.9 vs 2.7+/-9.8 ms, p<0.05). There was significant negative correlation between EF and delta eQTI (r=-0.63, p<0.05). The peak of changes in eQTI according to AV delay variations was steeper in patients with reduced cardiac function than in those with normal cardiac function. In conclusion, changes in eQTI according to AV delay variation are greater in patients with reduced cardiac function than in those with normal cardiac function, and the AV delay that gives the maximal eQTI can be easily determined in patients with reduced cardiac function.

Aged↗