Comparative effects of pioglitazone, glibenclamide, and voglibose on urinary endothelin-1 and albumin excretion in diabetes patients

Urinary endothelin (ET)-1 excretion is present in non-insulin dependent diabetes (NIDDM) patients with microalbuminuria, and an increase in circulating ET-1 precedes the microalbuminuric phase of renal injury related to diabetes. The aim of the present study was to determine whether various drugs alter urinary ET-1 levels and urinary albumin excretion (UAE) in NIDDM patients with microalbuminuria. Forty-five NIDDM patients with microalbuminuria were randomly assigned to three groups: those treated with pioglitazone at 30 mg/day (n=15), those treated with glibenclamide at 5 mg/day (n=15), and those treated with voglibose at 0.6 mg/day (n=15). Patients received these drugs for 3 months. UAE, urinary ET-1, and plasma ET-1 levels were measured in these patients before and after treatment. Before treatment, UAE, urinary ET-1, and plasma ET-1 levels differed little among the three groups. UAE in the 45 NIDDM patients (156.2+/-42.8 microg/min) was greater than that in 30 healthy controls (8.2+/-2.6 microg/min) (P<.001). Urinary ET-1 levels in the NIDDM patients (8.7+/-1.3 ng/g urinary creatinine (UC)) were significantly higher than that in the controls (2.4+/-0.2 ng/g UC) (P<.01). Plasma ET-1 levels, however, in the NIDDM patients (1.3+/-0.4 pg/ml) did not differ significantly from the levels in healthy controls (1.0+/-0.6 pg/ml). Pioglitazone but no glibenclamide or voglibose reduced UAE from 142.8+/-42.2 to 48. 4+/-18.2 microg/min (P<.01) and urinary ET-1 levels from 8.6+/-1.3 to 3.4+/-0.5 ng/g UC (P<.01). These data suggest pioglitazone to be effective in reducing UAE and urinary ET-1 concentrations in NIDDM patients with microalbuminuria.

Effects of angiotensin-converting enzyme inhibitor, angiotensin II receptor antagonist and calcium antagonist on urinary podocytes in patients with IgA nephropathy

The urinary podocyte is postulated to be a marker for estimation of the severity of active glomerular injury and a predictor of disease progression in children with glomerulonephritis. Non-dihydropyridine calcium antagonist, including verapamil, reduce proteinuria to an extent similar to that of the angiotensin-converting enzyme inhibitor (ACEI), including trandolapril, but to a greater extent than other antihypertensives. Angiotensin (Ang) II receptor antagonists, including candesartan cilexetil, show potent and long-term preventive effects against the progression of renal injury. The aim of the present study is to assess whether verapamil, trandolapril and candesartan cilexetil affect proteinuria and urinary podocytes in patients with IgA nephropathy. Thirty-two normotensive patients aged 18-54 years with biopsy-proven IgA nephropathy, nonnephrotic proteinuria (1-3 g/day), and normal renal function (creatinine clearance >80 ml/min) were studied. Twenty patients with diffuse mesangial proliferative glomerulonephritis (non-IgA PGN) and 20 healthy controls were also included in this study. The number of urinary podocytes in patients with advanced IgA nephropathy (n = 16) was significantly higher than that in patients with the disease in the mild stage (n = 16) (p < 0.01) or in patients with non-IgA PGN (p < 0.01). Urinary podocytes were not detected in healthy controls. The 32 patients with IgA nephropathy were randomly divided into four treatment groups: those treated with verapamil (120 mg/day, n = 8); those treated with trandolapril (2 mg/day, n = 8); those treated with candesartan cilexetil (8 mg/day, n = 8), and those given a placebo (n = 8). Treatment continued for 3 months. Antiproteinuric response in the trandolapril group was similar to that in the candesartan cilexetil group (-38 vs. -40%). The action of trandolapril or candesartan cilexetil was greater than that of verapamil (p < 0.01). Reduction in the number of urinary podocytes from baseline was significantly greater in patients treated with trandolapril or candesartan cilexetil than in patients treated with verapamil (p < 0.01). However, there was no difference between patients treated with trandolapril and those treated with candesartan cilexetil. Proteinuria and urinary podocytes were unaffected in the placebo group. These data suggest that urinary podocytes may be a marker of disease activity in adult patients with IgA nephropathy and that trandolapril and candesartan cilexetil are more effective than verapamil in reducing the number of podocytes.

Hemoperfusion with polymyxin B-immobilized fiber attenuates the increased plasma levels of thrombomodulin and von Willebrand factor from patients with septic shock

AIMS

The present study assessed whether plasma levels of thrombomodulin and von Willebrand factor (vWF) are altered in patients with septic shock and whether treatment with polymyxin B-immobilized fiber (PMX-F) affects these levels.

METHODS

Twenty-four patients with septic shock and 20 normal healthy controls were included in this study. Plasma levels of thrombomodulin and vWF were measured by enzyme immunoassay (EIA). The treatments with direct hemoperfusion using PMX-F column on patients with septic shock were repeated twice for 2 h each. Healthy controls were not subjected to hemoperfusion.

RESULTS

13 of 24 patients with septic shock survived (survival rate was 54.2%). Levels of blood endotoxin decreased significantly from 41.2 +/- 4.8 pg/ml at baseline to 13.2 +/- 3.6 pg/ml after direct hemoperfusion. Systolic blood pressure increased significantly from 82 +/- 6 mm Hg at baseline to 118 +/- 12 mm Hg after treatment. The patients with septic shock demonstrated significantly increased plasma levels of thrombomodulin (p < 0.001) and vWF (p < 0.001) compared with those in healthy controls. These increased levels of plasma thrombomodulin and vWF in patients with septic shock decreased significantly after treatment with PMX-F (p < 0.01).

CONCLUSION

These data suggest that plasma thrombomodulin and vWF may be related to septic shock and that PMX-F is effective in reducing these factors in patients with septic shock.

Identification of human cytochrome P450 isoforms involved in the 7-hydroxylation of chlorpromazine by human liver microsomes

Studies to identify the cytochrome P450 (CYP) isoform(s) involved in chlorpromazine 7-hydroxylation were performed using human liver microsomes and cDNA-expressed human CYPs. The kinetics of chlorpromazine 7-hydroxylation in human liver microsomes showed a simple Michaelis-Menten behavior. The apparent Km and Vmax values were 3.4+/-1.0 microM and 200.5+/-83.7 pmol/min/mg, respectively. The chlorpromazine 7-hydroxylase activity in human liver microsomes showed good correlations with desipramine 2-hydroxylase activity (r = 0.763, p < 0.05), a marker activity for CYP2D6, and phenacetin O-deethylase activity (r = 0.638, p < 0.05), a marker activity for CYP1A2. Quinidine (an inhibitor of CYP2D6) completely inhibited while alpha-naphthoflavone (an inhibitor of CYP1A2) marginally inhibited the chlorpromazine 7-hydroxylase activity in a human liver microsomal sample showing high CYP2D6 activity. On the other hand, alpha-naphthoflavone inhibited the chlorpromazine 7-hydroxylase activity to 55-65% of control in a human liver microsomal sample showing low CYP2D6 activity. Among eleven cDNA-expressed CYPs studied, CYP2D6 and CYP1A2 exhibited significant activity for the chlorpromazine 7-hydroxylation. The Km values for the chlorpromazine 7-hydroxylation of both cDNA-expressed CYP2D6 and CYP1A2 were in agreement with the Km values of human liver microsomes. These results suggest that chlorpromazine 7-hydroxylation is catalyzed mainly by CYP2D6 and partially by CYP1A2.

Effect of the antiplatelet drug dilazep dihydrochloride on urinary podocytes in patients in the early stage of diabetic nephropathy

OBJECTIVE

To determine whether the antiplatelet drug dilazep dihydrochloride affects the number of urinary podocytes in diabetic patients with microalbuminuria.

RESEARCH DESIGN AND METHODS

Fifty patients with type 2 diabetes and microalbuminuria (30 men and 20 women, mean age 48.6 years) and 30 age-matched control subjects (18 men and 12 women, mean age 49.2 years) were included in the study. No patients showed serum creatinine levels in excess of 2.0 mg/dl. Urinary podocytes were examined by immunofluorescence microscopy with monoclonal antibodies against podocalyxin.

RESULTS

Urinary podocytes were detected in 18 of the 50 microalbuminuric diabetic patients (mean, 1.3 cells/ml). Urinary podocytes were not detected in the remaining 32 patients or in the 30 healthy control subjects. Diabetic patients positive for urinary podocytes were divided into 2 treatment groups: a dilazep dihydrochloride treatment group (300 mg/day; n = 9, group A) and a placebo group (n = 9, group B). Treatments were continued for 6 months. In group A, microalbuminuria decreased significantly from 146 +/- 42 to 86 +/- 28 microg/min (P < 0.01) and urinary podocytes also decreased from 1.3 +/- 0.8 to 0.4 +/- 0.2 cells/ml (P < 0.01). However, in group B, microalbuminuria and urinary podocytes changed little over the study period.

CONCLUSIONS

Podocyte injury may occur in patients with early diabetic nephropathy, and dilazep dihydrochloride may be useful for preventing glomerular injury.

Urinary podocytes for the assessment of disease activity in lupus nephritis

BACKGROUND

Detection of podocytes in the urine indicates that severe injury of podocytes occurred in the glomerulus in children.

METHODS

The pathological significance of podocytes in the urine was determined in patients with lupus nephritis. Podocytes were detected by immunofluorescence using a monoclonal antibody against podocalyxin present on the surface of podocytes. Subjects who participated in the present study were of the following types: patients with systemic lupus erythematosus with stable renal function (group A, n = 8; WHO classes IlIa, b, IVb, and IVc at the time of biopsy); patients with clinically active lupus nephritis (group B, n = 8; WHO classes IVb and IVc); and healthy control subjects (group C, n = 10).

RESULTS

Podocytes were absent in the urine of subjects in groups A and C. However, podocytes were present in the urine of group B subjects. Patients in group B were examined monthly for urinary podocytes and were treated with methylprednisolone followed by prednisolone. Urinary podocytes were absent in all patients in group B after treatment.

CONCLUSIONS

These data indicate that urinary podocytes may be markers of the severity of lupus nephritis and that steroid therapy may be effective for podocyte injury in lupus nephritis.

Role of human cytochrome P450 3A4 in metabolism of medroxyprogesterone acetate

Medroxyprogesterone acetate (MPA) is a drug commonly used in endocrine therapy for advanced or recurrent breast cancer and endometrial cancer. The drug is extensively metabolized in the intestinal mucosa and in the liver. Cytochrome P450s (CYPs) involved in the metabolism of MPA were identified by using human liver microsomes and recombinant human CYPs. In this study, the overall metabolism of MPA was determined as the disappearance of the parent drug from an incubation mixture. The disappearance of MPA in human liver microsomes varied 2.6-fold among the 18 samples studied. The disappearance of MPA in the same panel of 18 human liver microsomes was significantly correlated with triazolam alpha-hydroxylase activity, a marker activity of CYP3A (r = 0.764; P < 0.001). Ketoconazole, an inhibitor of CYP3A4, potently inhibited the disappearance of MPA in 18 human liver microsomes. Anti-CYP3A antibody also inhibited 86% of the disappearance of MPA in human liver microsomes. Although sulfaphenazole (an inhibitor of CYP2C9) and S-mephenytoin (an inhibitor of CYP2C19) partially inhibited the disappearance of MPA, no effect of the anti-CYP2C antibody was observed. The disappearance of MPA did not correlate with either the activity metabolized via CYP2C9 (diclofenac 4'-hydroxylase activity) or the activity metabolized via CYP2C19 (S-mephenytoin 4'-hydroxylase activity). Among the 12 recombinant human CYPs (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5) studied, only CYP3A4 showed metabolic activity of MPA. These results suggest that CYP3A4 is mainly involved in the overall metabolism of MPA in human liver microsomes.

Characterization and tRNA recognition of mammalian mitochondrial seryl-tRNA synthetase

Animal mitochondrial protein synthesis systems contain two serine tRNAs (tRNAs(Ser)) corresponding to the codons AGY and UCN, each possessing an unusual secondary structure; the former lacks the entire D arm, and the latter has a slightly different cloverleaf structure. To elucidate whether these two tRNAs(Ser) can be recognized by the single animal mitochondrial seryl-tRNA synthetase (mt SerRS), we purified mt SerRS from bovine liver 2400-fold and showed that it can aminoacylate both of them. Specific interaction between mt SerRS and either of the tRNAs(Ser) was also observed in a gel retardation assay. cDNA cloning of bovine mt SerRS revealed that the deduced amino acid sequence of the enzyme contains 518 amino acid residues. The cDNAs of human and mouse mt SerRS were obtained by reverse transcription-polymerase chain reaction and expressed sequence tag data base searches. Elaborate inspection of primary sequences of mammalian mt SerRSs revealed diversity in the N-terminal domain responsible for tRNA recognition, indicating that the recognition mechanism of mammalian mt SerRS differs considerably from that of its prokaryotic counterpart. In addition, the human mt SerRS gene was found to be located on chromosome 19q13.1, to which the autosomal deafness locus DFNA4 is mapped.

Enantioselectivity of bunitrolol 4-hydroxylation is reversed by the change of an amino acid residue from valine to methionine at position 374 of cytochrome P450-2D6

The enantioselectivity of 4-hydroxylation of bunitrolol (BTL), a beta-adrenoceptor blocking drug, was studied in microsomes from human liver, human hepatoma (Hep G2) cells expressing CYP2D6, and lymphoblastoid cells expressing CYP2D6. Kinetics in human liver microsomes showed that the Vmax value for (+)-BTL was 2.1-fold that of (-)-BTL, and that the Km value for (+)-BTL was lower than that for the (-)-antipode, resulting in the intrinsic clearance (Vmax/Km) of (+)-BTL being 2.1-fold over its (-)-antipode. CYP2D6 (CYP2D6-met) expressed in Hep G2 cells had a methionine residue at position 373 of the amino acid sequence and a rat-type N-terminal peptide (MELLNGTGLWSM) instead of the human-type (MGLEALVPLAVIV), and showed enantioselectivity of [(+)-BTL < (-)-BTL] for the rate of BTL 4-hydroxylation. In contrast, enantioselectivity [(+)-BTL > (-)-BTL] for Hep G2-CYP2D6 (CYP2D6-val) with a human-type N-terminal peptide that had a valine residue at 374, which corresponds to the methionine of the CYP2D6-met variant, was the same as that for human liver microsomes. We further confirmed that CYP2D6-met and CYP2D6-val expressed in human lymphoblastoid cells, both of which have methionine and valine, respectively, at position 374 and a human-type N-terminal peptide, exhibited the same enantioselectivities as those obtained from CYP2D6-met and CYP2D6-val expressed in the Hep G2 cell system. These results indicate that the amino acid at 374 of CYP2D6 is one of the key factors influencing the enantioselectivity of BTL 4-hydroxylation.

Species difference in enantioselectivity for the oxidation of propranolol by cytochrome P450 2D enzymes

We examined and compared enantioselectivity in the oxidation of propranolol (PL) by liver microsomes from humans and Japanese monkeys (Macaca fuscata). PL was oxidized at the naphthalene ring to 4-hydroxypropranolol, 5-hydroxypropranolol and side chain N-desisopropylpropranolol by human liver microsomes with enantioselectivity of [R(+)>S(-)] in PL oxidation rates at substrate concentrations of 10 microM and 1 mM. In contrast, reversed enantioselectivity [R(+)<S(-)] in PL 5-hydroxylation and N-desalkylation rates at the same substrate concentrations was observed in monkey liver microsomes, although the selectivity was the same for PL 4-hydroxylation between the two species. All oxidation reactions of the PL enantiomers in human liver microsomes showed biphasic kinetics, i.e. the reactions could be expressed as the summation of a low-K(m) phase and a high-K(m) phase. Inhibition studies using antibodies and characterization of CYP2D6 enzymes expressed in insect cells or human lymphoblastoid cells indicated that the enantioselectivity of PL oxidation, especially the ring 4- and 5-hydroxylations reflected the properties of CYP2D6 in human liver microsomes. In monkey liver microsomes, all of the oxidation reactions of S(-)-PL showed biphasic kinetics, whereas ring 4- and 5-hydroxylations were monophasic and side chain N-desisopropylation was biphasic for R(+)-PL. Similarly, from the results of inhibition studies using antibodies and inhibitors of cytochrome P450 (P450), it appears that the reversed selectivity [R(+)<S(-)] of PL oxidation rates is catalyzed by CYP2D enzyme(s) in monkey liver at low substrate concentrations. These results indicate that different properties of P450s belonging to the 2D subfamily cause the reversed enantioselectivity between human and monkey liver microsomes.

Human T-cell receptor BV6 gene polymorphism in relation to expression level and CD4/CD8 skewness

Using 50 samples of umbilical cord blood lymphocytes from Japanese donors, we analysed two human T-cell receptor beta variable (TCRBV) genes, BV6S4 and BV6S5, for their polymorphism, usage frequencies and CD4/CD8 skewness. They showed contrasting CD4/CD8 skewness, BV6S4 to CD8+ T cells and BV6S5 to CD4+ T cells. Genotyping of the BV6S4 alleles (A1, A2 and A3) revealed two of the six possible BV6S4 genotypes, A1/A2 and A2/A2. Among the two BV6S4 genotypes, no significant difference was detected in usage frequency or CD4/CD8 skewness. On the other hand, genotyping of the BV6S5 alleles (A1 and A2) revealed all three possible BV6S5 genotypes, A1/A1, A1/A2 and A2/A2, and the gene usage frequency was high, in the order A1/A1 > A1/A2 > A2/A2. These results indicate that the amino acid substitutions in BV6S5 (S36R and G70E) are in some way associated with the expression level of this gene. In the analysis of CD4/CD8 skewness, the three BV6S5 genotypes had similar skewness, indicating that A1 alleles are expressed more frequently than A2 alleles in both CD4+ and CD8+ T-cell populations. Although BV6S5 exhibits marked skewness to CD4+ T cells, our results indicate that the higher expression of A1 alleles is not associated with the increased ratio of CD4+ T cells.

Regulation of cellular functions by nucleoside diphosphate kinases in mammals

The role of nucleoside diphosphate (NDP) kinases in cell growth, differentiation, and tumor metastasis in relation to signal transduction was investigated. The essential role of NDP kinase in cell growth was validated by coupling between reduced NDP kinase levels, induced by antisense oligonucleotides, and the suppression of proliferative activity of a cultured cell line. In addition, because NDP kinase levels are often enhanced with development and differentiation, as has been demonstrated in postmitotic cells and tissues, such as the heart and brain, we further examined this possibility using the bone tissue (osteoblasts) and a cultured cell line PC12D. The enhanced NDP kinase accumulation was demonstrated in the matured osteoblasts in vivo and in vitro by immunohistochemistry. In PC12D cells, neurite outgrowth took place in NDP kinase beta-transfected clones without differentiation inducers, which was accompanied by prolongation of doubling time. Neurite outgrowth, triggered by nerve growth factor and a cyclic AMP analog, was down-regulated upon forced expression of inactive mutant NDP kinase by virtue of a dominant negative effect. NDP kinase alpha-transfected rat mammary adenocarcinoma cells (MTLn3) and nm23-H2-transfected human oral squamous cell carcinoma cells (LMF4) manifested reduced metastatic potential and were associated with an altered sensitivity to environmental factors, such as motility and growth factors. NDP kinase alpha, compared to NDP kinase beta, was involved in a wide variety of the cellular phenomena examined. Taken together, NDP kinase isoforms appear to elicit both their own respective and common effects. They may have an ability to lead cells to both proliferative and differentiated states by modulating responsiveness to environmental factors, but their fate seems to depend on their surrounding milieu.

Effect of plasma exchange on serum tissue inhibitor of metalloproteinase 1 and cytokine concentrations in patients with fulminant hepatitis

AIMS

The present study assessed whether the serum concentrations of tissue inhibitor of metalloproteinase 1 (TIMP-1) and cytokines are altered in patients with fulminant hepatitis and whether plasma exchange affects these concentrations.

METHODS

Fifteen patients with fulminant hepatitis, 14 patients with severe acute hepatitis, and 20 healthy controls were included in this study. The serum levels of tumor necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), interleukin 6 (IL-6), transforming growth factor beta (TGF-beta), and TIMP-1 were determined in all patients upon hospital admission and before and after a single course of plasma exchange in the patients with fulminant hepatitis.

RESULTS

Ten out of the 15 patients with fulminant hepatitis and all patients with severe acute hepatitis survived. Serum TNF-alpha, IL-6, TGF-beta, and TIMP-1 levels in patients with fulminant hepatitis were significantly higher than the levels in patients with severe acute hepatitis (p < 0.01). IL-1beta was not detectable in either group. Plasma exchange reduced the increased serum concentrations of TNF-alpha, IL-6, TGF-beta, and TIMP-1 in patients with fulminant hepatitis (p < 0.01).

CONCLUSIONS

These data suggest that increased serum levels of TIMP-1 and cytokines may reflect severe hepatic inflammation and that plasma exchange is an effective therapy to reduce these levels.

The urinary podocyte as a marker for the differential diagnosis of idiopathic focal glomerulosclerosis and minimal-change nephrotic syndrome

BACKGROUND/AIMS

Detection of podocytes in the urine sediment of children indicates that severe podocyte injury occurred in the glomerulus. Focal glomerulosclerosis (FGS) and minimal-change nephrotic syndrome (MCNS) are kidney diseases characterized by massive proteinuria. The aim of the present study was to determine whether urinary podocytes can be detected in patients with idiopathic FGS or MCNS and whether immunosuppression therapy alters these cells.

METHODS

Twenty patients with MCNS (nephrotic stage, n = 12; remission stage, n = 8), 15 patients with FGS and 20 healthy controls were included in the present study. Urinary podocytes were stained by immunofluorescence. All patients with MCNS at the nephrotic stage received prednisolone for 6 months, and all patients with FGS received some form of immunosuppression therapy including prednisolone, cyclophosphamide or mizoribine for 12 months.

RESULTS

The 12 nephrotic-stage MCNS patients achieved remission after treatment. Seven of the 15 FGS patients also achieved remission, but the other 8 remained in the nephrotic stage. Urinary podocytes were not detected in any patient with MCNS nor were they detected in healthy controls. Urinary podocytes were detected in all FGS patients (mean, 4.2 cells/ml) before treatment and the number of cells decreased in the 7 patients who achieved remission. The number of podocytes was unchanged in the other 8 patients even after treatment.

CONCLUSION

Urinary podocytes may be a useful diagnostic indicator for differentiation between FGS and MCNS. These cells may also mark disease progression in cases of FGS.

Prediction of in vivo interaction between triazolam and erythromycin based on in vitro studies using human liver microsomes and recombinant human CYP3A4

PURPOSE

To quantitatively predict the in vivo interaction between triazolam and erythromycin, which involves mechanism-based inhibition of CYP3A4, from in vitro studies using human liver microsomes (HLM) and recombinant human CYP3A4 (REC).

METHODS

HLM or REC was preincubated with erythromycin in the presence of NADPH and then triazolam was added. alpha- and 4-hydroxy (OH) triazolam were quantified after a 3 min incubation and the kinetic parameters for enzyme inactivation (k(inact) and K('app)) were obtained. Drug-drug interaction in vivo was predicted based on a physiologically-based pharmacokinetic (PBPK) model, using triazolam and erythromycin pharmacokinetic parameters obtained from the literature and kinetic parameters for the enzyme inactivation obtained in the in vitro studies.

RESULTS

Whichever enzyme was used, triazolam metabolism was not inhibited without preincubation, even if the erythromycin concentration was increased. The degree of inhibition depended on preincubation time and erythromycin concentration. The values obtained for k(inact) and K('app) were 0.062 min(-1) and 15.9 microM (alpha-OH, HLM), 0.055 min(-1) and 17.4 microM (4-OH, HLM), 0.173 min(-1) and 19.1 microM (alpha-OH, REC), and 0.097 min(-1) and 18.9 microM (4-OH, REC). Based on the kinetic parameters obtained using HLM and REC, the AUCpo of triazolam was predicted to increase 2.0- and 2.6-fold, respectively, following oral administration of erythromycin (333 mg t.i.d. for 3 days), which agreed well with the reported data.

CONCLUSIONS

In vivo interaction between triazolam and erythromycin was successfully predicted from in vitro data based on a PBPK model involving a mechanism-based inhibition of CYP3A4.

Prediction of in vivo drug-drug interactions between tolbutamide and various sulfonamides in humans based on in vitro experiments

Drug-drug interactions between tolbutamide and sulfonamides have extensively been reported. We attempted to predict the in vivo interaction between tolbutamide and sulfonamides from the in vitro metabolic inhibition studies. The inhibition constant (K(i)) was derived from the inhibitory effects of eight sulfonamides (sulfaphenazole, sulfadiazine, sulfamethizole, sulfisoxazole, sulfamethoxazole, sulfapyridine, sulfadimethoxine, and sulfamonomethoxine) on tolbutamide metabolism. We found that the inhibitory effect of sulfaphenazole was greatest among the eight sulfonamides examined. Furthermore, the contribution of each P450 enzyme to tolbutamide metabolism was investigated by using recombinant P450 enzymes. Although cytochrome P450 (CYP) 2C8, 2C9, and 2C19 metabolized tolbutamide, the main enzyme involved was CYP2C9. The K(i) values of several sulfonamides were comparable between human liver microsomes and recombinant CYP2C9. The maximum unbound plasma concentration of sulfonamides in the portal vein was calculated from literature data on the pharmacokinetics of sulfonamides. Using the K(i) values obtained from in vitro inhibition studies, the degree of increase in tolbutamide area under the plasma concentration-time curve (AUC) was predicted. About 4.8- and 1.6-fold increases in tolbutamide AUC were predicted by coadministration of sulfaphenazole and sulfamethizole, respectively, which agreed well with the reported increases in humans. Furthermore, the increase in tolbutamide AUC by coadministration of sulfadiazine, sulfisoxazole, and sulfamethizole was predicted to be 1.5- to 2. 6-fold, although the corresponding in vivo effects have not been reported. It is concluded that some of these sulfonamides have to be carefully coadministered with CYP2C9 substrates such as tolbutamide although coadministration of sulfaphenazole needs the greatest care.

Inhibitory effects of amiodarone and its N-deethylated metabolite on human cytochrome P450 activities: prediction of in vivo drug interactions

AIMS

To predict the drug interactions of amiodarone and other drugs, the inhibitory effects and inactivation potential for human cytochrome P450 (CYP) enzymes by amiodarone and its N-dealkylated metabolite, desethylamiodarone were examined.

METHODS

The inhibition or inactivation potency of amiodarone and desethylamiodarone for human CYP activities were investigated using microsomes from B-lymphoblastoid cell lines expressing CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4. The in vivo drug interactions of amiodarone and desethylamiodarone were predicted in vitro using the 1+Iu/Ki values.

RESULTS

Amiodarone weakly inhibited CYP2C9, CYP2D6, and CYP3A4-mediated activities with Ki values of 45.1-271.6 microm. Desethylamiodarone competitively inhibited the catalytic activities of CYP2D6 (Ki=4.5 microm ) and noncompetitively inhibited CYP2A6 (Ki=13.5 microm ), CYP2B6 (Ki=5.4 microm ), and CYP3A4 (Ki=12.1 microm ). The catalytic activities of CYP1A1 (Ki=1.5 microm, alpha=5.7), CYP1A2 (Ki=18.8 microm, alpha=2.6), CYP2C9 (Ki=2.3 microm, alpha=5.9), and CYP2C19 (Ki=15.7 microm, alpha=4.5) were inhibited by desethylamiodarone with mixed type. The 1+Iu/Ki values of desethylamiodarone were higher than those of amiodarone. Amiodarone inactivated CYP3A4, while desethylamiodarone inactivated CYP1A1, CYP1A2, CYP2B6, and CYP2D6.

CONCLUSIONS

The interactions between amiodarone and other drugs might occur via the inhibition of CYP activities by its N-dealkylated metabolite, desethylamiodarone, rather than by amiodarone itself. In addition, the inactivation of CYPs by desethylamiodarone as well as by amiodarone would also contribute to the drug interactions.

Polymyxin b-immobilized fiber reduces increased plasma endothelin-1 concentrations in hemodialysis patients with sepsis

We studied whether plasma endothelin (ET)-1 concentrations are altered in patients with septic shock who are undergoing hemodialysis and whether polymyxin B-immobilized fiber (PMX-F) treatment affects on these concentrations. Fifteen hemodialysis patients with septic shock treated with PMX-F (group A), 10 such patients who received conventional treatments (group B), 20 hemodialysis patients without septic shock (group C) and 20 healthy controls (group D) were included in this study. Plasma ET1 levels were measured by radioimmunoassay and endotoxin levels were determined by endospecy test. The survival rate in group A (67%) was higher than that in group B (30%). Blood endotoxin levels decreased significantly from 36.4+/-8.2 pg/mL to 10.6+/-3.8 pg/mL (p < 0.01) after PMX-F treatment in group A. The pretreatment plasma ET-1 levels in patients in group A (58.6+/-9.8 pg/mL) and group B (56.8+/-7.8 pg/mL) were significantly higher than those in group C (p < 0.01) and group D (p < 0.001). Plasma ET-1 levels in group C (11.2+/-3.2 pg/mL) were higher than those in group D (2.6+/-0.6 pg/mL) (p < 0.01). Plasma ET-1 levels following hemodialysis (10.9+/-3.0 pg/mL) were not altered significantly compared with those before hemodialysis. Plasma ET-1 levels decreased significantly in group A after PMX-F treatment (11.4+/-3.6 pg/mL) (p < 0.01); the levels in group B were not altered after conventional treatment. Our data suggest that ET-1 may be associated with septic shock in patients undergoing hemodialysis and that PMX-F is effective in reducing plasma ET-1 levels in these patients.

Inhibition of human cytochrome P450 enzymes by 1,4-dihydropyridine calcium antagonists: prediction of in vivo drug-drug interactions

OBJECTIVE

1,4-Dihydropyridine calcium antagonists such as nifedipine are potent vasodilators. It is now commonly agreed that the oxidation of 1,4-dihydropyridine into pyridine, which is one of the main metabolic pathways, is catalysed by the cytochrome P450 (CYP) 3A4 isoform. In the present study, the inhibitory effects of 13 kinds of 1,4-dihydropyridine calcium antagonists clinically used in Japan on human CYP-isoform-dependent reactions were investigated to predict the drug interactions using microsomes from human B-lymphoblast cells expressing CYP.

RESULTS

The specific activities for human CYP isoforms included 7-ethoxyresorfin O-deethylation (CYP1A1), phenacetin O-deethylation (CYP1A2), coumarin 7-hydroxylation (CYP2A6), 7-benzyloxyresorufin O-dealkylation (CYP2B6), S-warfarin 7-hydroxylation (CYP2C9), S-mephenytoin 4'-hydroxylaion (CYP2C19), bufuralol 1'-hydroxylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and testosterone 6beta-hydroxylation (CYP3A4). Benidipine and amlodipine competitively inhibited the CYP1A1 activity. Nifedipine, nisoldipine and aranidipine competitively inhibited the CYP1A2 activity. No 1,4-dihydropyridie calcium antagonists used in this study inhibited the CYP2A6 activity. Barnidipine and amlodipine inhibited the CYP2B6 activity. Nicardipine, benidipine, manidipine and barnidipine competitively inhibited the CYP2C9 and CYP2D6 activities. Inhibition extent of the CYP2E1 activity by nifedipine and aranidipine were weak. Nicardipine, benidipine and barnidipine inhibited the CYP2C19 and CYP3A4 activities. Among the human CYP isoforms investigated, the inhibitory effects of 1,4-dihydropyridine calcium antagonists were potent on human CYP1A2, CYP2B6, CYP2C9, CYP2C19 and CYP2D6 as well as CYP3A4. Furthermore, the isoform selectivity of inhibition by 1,4-dihydropyridine calcium antagonists was clarified.

CONCLUSIONS

In consideration of the Ki values obtained in the in vitro inhibition study and the concentration of 1,4-dihydropyridine calcium antagonists in human liver, the possibility of in vivo drug interactions of nicardipine and other drugs which are mainly metabolised by CYP2C9 and/or CYP3A4 was suggested. The inhibition of human CYP isoforms by 1,4-dihydropyridine calcium antagonists except nicardipine might be clinically insignificant.

Solitary subependymal giant cell astrocytoma: case report

In this report, we describe a case of subependymal giant cell astrocytoma in a patient lacking clinical symptoms of tuberous sclerosis. The absence of any features of tuberous sclerosis initially dissuaded us from including subependymal giant cell astrocytoma in our differential diagnosis.

In vitro inhibitory effects of troglitazone and its metabolites on drug oxidation activities of human cytochrome P450 enzymes: comparison with pioglitazone and rosiglitazone

1. Investigated were the effects of a new oral antidiabetic drug, troglitazone, and its three metabolites and antidiabetic drug candidates pioglitazone and rosiglitazone on xenobiotic oxidations catalyzed by nine recombinant human cytochrome P450 (P450 or CYP) enzymes and by human liver microsomes. 2. Troglitazone (5 microM) significantly inhibited CYP2C8-dependent paclitaxel 6alpha-hydroxylation and CYP2C9-dependent S-warfarin 7-hydroxylation. On the other hand, pioglitazone and rosiglitazone (50 microM) only slightly inhibited these xenobiotic oxidation activities catalyzed by CYP2C enzymes. 3. The inhibitory potential of troglitazone (50% inhibition concentration, IC50) was approximately 5 microM for drug oxidations catalyzed by CYP2C9 and CYP2C8 and approximately 20 microM for activities catalyzed by CYP2C19 and CYP3A4 respectively. For the three metabolites of troglitazone tested, a quinone-type metabolite (M3) was the most potent inhibitor for CYP2C enzymes, followed by a sulphate conjugate (M1); effects of a glucuronide (M2) were very weak. The inhibitory effects of the parent drug were more potent than those of metabolites. Troglitazone and M3 inhibited P450 activities mainly through a competitive manner with Ki = 0.2-1.7 microM and 1.4-8.8 microM respectively. 4. In three human liver microsomes, troglitazone and its metabolites also inhibited paclitaxel 6alpha-hydroxylation, S-warfarin 7-hydroxylation, S-mephenytoin 4'-hydroxylation, and testosterone 6beta-hydroxylation with similar IC50, as observed for the recombinant P450 enzyme systems. 5. These results suggest that xenobiotic oxidations by P450 enzymes are more substantially affected by troglitazone and its metabolites than pioglitazone or rosiglitazone, and that drug interactions may be of much importance to understand the basis for the pharmacological and toxicological actions of this new oral antidiabetic drug.

Elevation of serum levels of metalloproteinase-1, tissue inhibitor of metalloproteinase-1 and type IV collagen, and plasma levels of metalloproteinase-9 in polycystic kidney disease

Several studies on polycystic kidney disease (PKD) have revealed a number of extracellular matrix (ECM) abnormalities, suggesting that an abnormal ECM plays a role in the development of tubular cysts. Cystic kidney tubules synthesize and secrete high levels of metalloproteinases (MMP), which may participate in the restructuring of the tubular basement membrane. The aim of the present study was to determine whether serum MMP-1, tissue inhibitor of metalloproteinase (TIMP)-1, and type IV collagen levels, and plasma MMP-9 levels were altered in patients with PKD. Sixteen patients with autosomal dominant polycystic kidney disease, and 20 healthy controls were included in this study. Specific enzyme immunoassays were used to measure MMP-1, MMP-9, TIMP-1, and type IV collagen levels. Serum MMP-1 (14.8 +/- 3.6 ng/ml), TIMP-1 (288.6 +/- 48.6 ng/ml), and type IV collagen (192.6 +/- 38.8 ng/ml) concentrations, and plasma MMP-9 (90.2 +/- 26.8 ng/ml) concentrations in patients with PKD were significantly higher than those in healthy controls (MMP-1; 6.6 +/- 0.9 ng/ml, p < 0.01, MMP-9; 36.4 +/- 12.2 ng/ml, p < 0.01, TIMP-1; 164.6 +/- 22.8 ng/ml, p < 0.01, and type IV collagen; 86.6 +/- 14.2 ng/ml, p < 0.001). The present results suggest that ECM abnormalities associated with cystic kidney may result from aberrant degradation as well as from abnormal synthesis of ECM components.

Role of human CYP2B6 in S-mephobarbital N-demethylation

The role of cytochrome P-450s (CYPs) in S-mephobarbital N-demethylation was investigated by using human liver microsomes and cDNA-expressed CYPs. Among the 10 cDNA-expressed CYPs studied (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4), only CYP2B6 could catalyze S-mephobarbital N-demethylation. The apparent K(m) values of human liver microsomes for S-mephobarbital N-demethylation were close to that of cDNA-expressed CYP2B6 (about 250 microM). The N-demethylase activity of S-mephobarbital in 10 human liver microsomes was strongly correlated with immunodetectable CYP2B6 levels (r = 0.920, p<.001). Orphenadrine (300 microM), a CYP2B6 inhibitor, inhibited the N-demethylase activity of S-mephobarbital in human liver microsomes to 29% of control activity. Therefore, it appears that CYP2B6 mainly catalyzes S-mephobarbital N-demethylation in human liver microsomes.

Isoform selective inhibition and inactivation of human cytochrome P450s by methylenedioxyphenyl compounds

1. A series of methylenedioxyphenyl compounds were evaluated for their inhibitory and inactivation effects on nine human cytochrome P450 (CYP) activities using microsomes from human B-lymphoblast cells expressing specific human CYP isoforms. 2. Methylenedioxyphenyl compounds which possess a bulky structure such as 1,4-benzothiazine showed substantial inhibition of S-warfarin 7-hydroxylation catalysed by CYP2C9, S-mephenytoin 4'-hydroxylation by CYP2C19, bufuralol 1'-hydroxylation by CYP2D6, and testosterone 6beta-hydroxylation by CYP3A4. Regarding ethoxyresorufin O-deethylation catalysed by CYP1A1 and benzyloxyresorufin O-dealkylation by CYP2B6, the subtle change of a substitution of the 1,4-benzothiazine structure affected the inhibition selectivity. Ethoxyresorufin O-deethylation by CYP1A2, coumarin 7-hydroxylation by CYP2A6, and chlorzoxazone 6-hydroxylation by CYP2E1 were not inhibited by almost any of the methylenedioxyphenyl compounds. The inhibitory effects of methylenedioxyphenyl compounds that possess a short chain amino group on the human CYP isoforms were not significant. 3. The methylenedioxyphenyl compounds inactivated CYP1A1 (k(inact) = 0.034 min(-1) and K(i) = 0.81 microM), CYP2C9 (k(inact) = 0.041 and 0.042 min(-1) and K(i) = 0.56 and 0.15 microM), CYP2D6 (k(inact) = 0.044-0.339 min(-1) and K(i) = 0.21-19.88 microM), and CYP3A4 (k(inact) = 0.076-0.251 min(-1) and K(i) = 0.25-0.69 microM). These results suggested that the methylenedioxyphenyl compounds investigated in this study would be potent mechanism-based inactivators of these human CYP isoforms. In contrast, CYP2B6 and CYP2C19 were not inactivated. 4. The present study suggested that the selectivity of inhibition or inactivation of human CYP isoforms by methylenedioxyphenyl compounds may vary according to the structure of the side chain.

Azelastine N-demethylation by cytochrome P-450 (CYP)3A4, CYP2D6, and CYP1A2 in human liver microsomes: evaluation of approach to predict the contribution of multiple CYPs

Azelastine, an antiallergy and antiasthmatic drug, has been reported to be mainly N-demethylated to desmethylazelastine in humans. In the present study, Eadie-Hofstee plots of azelastine N-demethylation in human liver microsomes were biphasic. In microsomes from human B-lymphoblast cells, recombinant cytochrome P-450 (CYP)2D6 and CYP1A1 exhibited higher azelastine N-demethylase activity than did other CYP enzymes. On the other hand, recombinant CYP3A4 and CYP1A2 as well as CYP1A1 and CYP2D6 in microsomes from baculovirus-infected insect cells were active in azelastine N-demethylation. The K(M) value of the recombinant CYP2D6 (2.1 microM) from baculovirus-infected insect cells was similar to the K(M) value of the high-affinity (2.4+/-1.3 microM) component in human liver microsomes. On the other hand, the K(M) values of the recombinant CYP3A4 (51.1 microM) and CYP1A2 (125.4 microM) from baculovirus-infected insect cells were similar to the K(M) value of the low-affinity (79.7+/-12.8 microM) component in human liver microsomes. Bufuralol inhibited the high-affinity component, making the Eadie-Hofstee plot in human liver microsomes monophasic. Azelastine N-demethylase activity in human liver microsomes (5 microM azelastine) was inhibited by ketoconazole, erythromycin, and fluvoxamine (IC(50) = 0.08, 18.2, and 17.2 microM, respectively). Azelastine N-demethylase activity in microsomes from twelve human livers was significantly correlated with testosterone 6beta-hydroxylase activity (r = 0.849, p<.0005). The percent contributions of CYP1A2, CYP2D6, and CYP3A4 in human livers were predicted using several approaches based on the concept of correction with CYP contents or relative activity factors (RAFs). Our data suggested that the approach using RAF(CL) (RAF as the ratio of clearance) is most predictive of the N-demethylation clearance of azelastine because it best reflects the observed N-demethylation clearance in human liver microsomes. Summarizing the results, azelastine N-demethylation in humans liver microsomes is catalyzed mainly by CYP3A4 and CYP2D6, and CYP1A2 to a small extent (in average, 76.6, 21.8, and 3.9%, respectively), although the percent contribution of each isoform varied among individuals.

Oxidation of troglitazone to a quinone-type metabolite catalyzed by cytochrome P-450 2C8 and P-450 3A4 in human liver microsomes

Troglitazone, a new oral antidiabetic drug, is reported to be mostly metabolized to its conjugates and not to be oxidized by cytochrome P-450 (P-450) enzymes. Of fourteen cDNA-expressed human P-450 enzymes examined, CYP1A1, CYP2C8, CYP2C19, and CYP3A4 were active in catalyzing formation of a quinone-type metabolite at a concentration of 10 microM troglitazone, whereas CYP3A4 had the highest catalytic activity at 100 microM substrate. In human liver microsomes, rates of the quinone-type metabolite formation (at 100 microM) were correlated well with rates of testosterone 6beta-hydroxylation (r = 0.98), but those at 10 microM troglitazone were not correlated with any of several marker activities of P-450 enzymes. Quercetin efficiently inhibited quinone-type metabolite formation (at 10 microM troglitazone) in human samples that contained relatively high levels of CYP2C, whereas ketoconazole affected these activities in liver microsomes in which CYP3A4 levels were relatively high. Anti-CYP2C antibodies strongly inhibited quinone-type metabolite formation (at 10 microM troglitazone) in CYP2C-rich human liver microsomes (by approximately 85%); the intensity of this effect depended on the human samples and their P-450 status. The results suggest that in human liver both CYP2C8 and CYP3A4 have major roles in quinone-type metabolite formation and that the hepatic contents of these two P-450 forms determine which P-450 enzymes play major roles in individual humans. CYP3A4 may be expected to play a role in formation of quinone-type metabolite from troglitazone even at a low concentration in humans.

[Transition of branched-chain amino acids and tyrosine ratio (BTR) in the blood of acute hepatitis patients]

The molar ratio of branched-chain amino acids to tyrosine (BTR) correlates well with the Fischer ratio, and can be measured in a short period of time. It is regarded as the method of analysis that will eventually replace the Fischer ratio. But clinical significance of BTR in terms of acute liver disorders has not been examined thoroughly as of yet. In this study, we measured BTR of 34 patients with acute hepatitis, and examined the transition of the acute period of acute hepatitis and its recovery process. Thirty-four patients diagnosed with acute viral hepatitis became subjects of examination (16 patients of A type, 15 patients of B type, 1 patient of C type, 2 patients of non-A, non-B, non-C type). Out of the 34 patients, 11 were in serious stages (HPT under 40%), including 3 in fulminant condition. By using preserved serum obtained during the acute period (within 1 week of the highest transaminase value), recovery period (within 4 weeks), and treatment period (3 months and later), measurements were conducted with Diacolor:BTR (enzymatic analysis, ONO Pharmaceutical Co., Ltd.), and the results were compared with those of 50 healthy subjects (25 men, 25 women). BTR correlated well with the Fischer ratio for chronic hepatic patients, and with albumin (Alb), PT, and ICGR15 as well, proving that it is useful as an indicator of hepatic reserve ability. But BTR has not been thoroughly examined as it relates to acute liver disorders. In this study, BTR fell in the acute period, correlating with the serious period, proving that it is a useful indicator. For acute liver damage, BTR supports conventional indicators (Alb, Ch-E, HGF, etc.) for assessing serious damage. Also, it has been suggested that measuring the passage of BTR could be the indicator of true recovery, including amino acid metabolism for liver disorders.

Plasma, urinary, and erythrocyte concentrations of guanidino compounds in patients with chronic renal failure

Guanidino compounds are among the most likely candidates for uremic toxins. We determined the plasma, erythrocyte, and urinary concentration of guanidino compounds in 30 hemodialysis patients and 15 patients with chronic renal failure who had not undergone hemodialysis. Guanidino compounds were measured by high-performance liquid chromatography. Plasma levels of taurocyamine, guanidinosuccinic acid, alpha-N-acetyl-L-arginine, creatine, guanidinobutyric acid, guanidine, and methylguanidine were significantly increased in patients with chronic renal failure with or without hemodialysis. In contrast, plasma guanidinoacetic acid concentrations were significantly decreased. Erythrocyte concentrations of creatinine, guanidinosuccinic acid, guanidine and methylguanidine were also markedly elevated. No correlation was observed between plasma creatinine concentration and erythrocyte concentration of guanidinosuccinic acid or methylguanidine. However, there was a significant correlation between plasma and erythrocyte methylguanidine, and between plasma and erythrocyte guanidinosuccinic acid.

Activation of phenacetin O-deethylase activity by alpha-naphthoflavone in human liver microsomes

1. The roles of different human cytochrome P450s (CYP) in phenacetin O-deethylation were investigated using human liver microsomes and recombinant proteins. Phenacetin O-deethylase (POD) activities in human liver microsomes at substrate concentrations of 10 and 500 microM were inhibited by 0.1 and 1 microM alpha-naphthoflavone and activated by 10 and 100 microM alpha-naphthoflavone. The activation of POD activity in human liver microsomes by alphanaphthoflavone was inhibited by 100 microM aniline, anti-CYP2E1 antibody, 1 microM ketoconazole and anti-CYP3A4 antibody. 2. In recombinant CYP from human B-lymphoblast cells, POD activities at a phenacetin concentration of 500 microM were detected for CYP2E1 and CYP3A4, as well as CYP1A2, CYP1A1, CYP2C19, CYP2C9 and CYP2A6. In recombinant CYP from human B-lymphoblast cells or baculovirus-infected insect cells and in reconstituted systems, a requirement of cytochrome b5 (b5) for POD activities catalysed by CYP2E1 and CYP3A4 was observed. The activation of POD activity by alpha-naphthoflavone was observed for CYP3A4, but not for CYP2E1. Co-expression of b5 with CYP3A4 enhanced the activation of POD activity by alpha-naphthoflavone. 3. In the absence of alpha-naphthoflavone, the POD activity in pooled human liver microsomes at 500 microM phenacetin was significantly inhibited (p<0.0001) by 10 microM fluvoxamine, but not by 1 microM ketoconazole. In the presence of alpha-naphthoflavone, the activity was significantly inhibited (p<0.0001) by 1 microM ketoconazole, but not by 10 microM fluvoxamine. 4. Inter-individual differences in the effects of alpha-naphthoflavone on POD activity in human liver microsomes were observed, and the involvement of CYP3A4 as well as CYP1A2 in POD activity in human liver was identified even at a low substrate concentration.

Association between alcohol intake and subjective health: the Sotetsu Study

Subjective health and alcohol intake are important predictors of mortality. There have been few epidemiological studies, however, of the relationship between alcohol consumption and subjective health among the Japanese. The purpose of this study is to investigate the association between alcohol consumption and subjective health. The study subjects were 2,020 Japanese male employees, who were free from serious disease conditions. The data on subjective health and alcohol consumption were obtained by means of self-reported questionnaire. The subjects who responded "poor health" in the answer to the question about the subjective health status were considered to be in ill-health. Ethanol intake per day was calculated by multiplying the frequency of drinking by the ethanol intake per drinking occasion and summing up for each alcoholic beverage. Age, smoking status, physical activity, and sleeping hours were treated as confounding factors. As a result, subjects who consumed 25-36 or 49 g ethanol or more per day had a significantly lower risk of self-rated ill-health compared with those who had never drunk, and a significantly inverse trend was found independent of age, smoking status, physical activity, and sleeping hours. In conclusion, moderate drinkers have a lower risk of self-rated ill-health among Japanese male employees investigated.

Enhancement of cytochrome P-450 3A4 catalytic activities by cytochrome b(5) in bacterial membranes

Activities of testosterone, nifedipine, and midazolam oxidation by recombinant cytochrome P-450 (P-450) 3A4 coexpressed with human NADPH-P-450 reductase (NPR) in bacterial membranes (CYP3A4/NPR membranes) were determined in comparison with those of other recombinant systems and of human liver microsomes with high contents of CYP3A4. Growth conditions for Escherichia coli transformed with the bicistronic construct affected expression levels of CYP3A4 and NPR; an excess of NPR over P-450 in membrane preparations enhanced CYP3A4-dependent testosterone 6beta-hydroxylation activities of the CYP3A4/NPR membranes. Cytochrome b(5) (b(5)) and apolipoprotein b(5) further enhanced the testosterone 6beta-hydroxylation activities of CYP3A4/NPR membranes after addition to either bacterial membranes or purified enzymes. NPR was observed to enhance catalytic activity when added to the CYP3A4/NPR membranes, either in the form of bacterial membranes or as purified NPR (in combination with cholate and b(5)). Apparent maximal activities of testosterone 6beta-hydroxylation in CYP3A4/NPR membranes were obtained when the molar ratio of CYP3A4/NPR/b(5) was adjusted to 1:2:1 by mixing membranes containing each protein. Testosterone 6beta-hydroxylation, nifedipine oxidation, and midazolam 4- and 1'-hydroxylation activities in CYP3A4/NPR membranes plus b(5) systems were similar to those measured with microsomes of insect cells coexpressing CYP3A4 with NPR and/or of human liver microsomes, based on equivalent CYP3A4 contents. These results suggest that CYP3A4/NPR membrane systems containing b(5) are very useful models for prediction of the rates for liver microsomal CYP3A4-dependent drug oxidations.

Application of a rigid endoscope to the microsurgical management of 54 cerebral aneurysms: results in 48 patients

OBJECT

To enhance visual confirmation of regional anatomy, endoscopy was introduced during microsurgery for cerebral aneurysms. The risks and benefits are analyzed in the present study.

METHODS

The endoscopic technique was used during microsurgery for 54 aneurysms in 48 patients. Forty-three aneurysms were located in the anterior circulation and 11 were in the posterior circulation. Thirty-eight aneurysms (70.4%) had not ruptured. All ruptured aneurysms in the present series produced Hunt and Hess Grade I or II subarachnoid hemorrhage. After initial exposure achieved with the aid of a microscope, the rigid endoscope was introduced to confirm the regional anatomy, including the aneurysm neck and adjacent structures. The necks of 43 aneurysms were clipped using microscopic control or simultaneous microscopic/endoscopic control. After clipping, the positions of the clip and nearby structures were inspected using the endoscope. Use of the neuroendoscope provided useful information that further clarified the regional anatomy in 44 cases (81.5%) either before or after neck clipping. In nine cases (16.7%), these details were available only with the use of the endoscope. In five cases (9.3%), the surgeons reapplied the clip on the basis of endoscopic information obtained after the initial clipping. There were two cases in which surgical complications were possibly related to the endoscopic procedures (one patient with asymptomatic cerebral contusion and another with transient oculomotor palsy).

CONCLUSIONS

It is the authors' impression that the use of the endoscope in the microsurgical management of cerebral aneurysms enhanced the safety and reliability of the surgery. However, there is a prerequisite for the surgeon to be familiar with this instrumentation and fully prepared for the risks and inconveniences of endoscopic procedures.

Involvement of CYP2E1 as A low-affinity enzyme in phenacetin O-deethylation in human liver microsomes

Phenacetin O-deethylation (POD) exhibits biphasic kinetics in human liver microsomes. Although cytochrome P-450 (CYP) 1A2 is responsible for the high-affinity component of POD, the enzyme(s) that catalyzes the low-affinity reaction is still unknown. We examined the roles of human CYPs in POD by using human liver microsomes and recombinant CYPs from baculovirus-infected insect cells. Of the recombinant CYPs studied, CYP1A2 showed the highest POD activity. CYP1A1, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 also showed POD activity at 500 microM phenacetin. K(M) values of recombinant CYP1A2 and CYP2E1 (28 +/- 2 microM and 785 +/- 125 microM, respectively) were similar to those of the high- and low-affinity components of POD in pooled human liver microsomes (15 +/- 5 and 894 +/- 189 microM, respectively). Fluvoxamine (10 microM) and anti-CYP1A2 antibodies potently inhibited POD activity at 500 microM phenacetin in pooled human liver microsomes to 22.8 and 34.2% of controls, respectively. CYP2E1 inhibitors diethyldithiocarbamate and aniline also reduced POD activity. The combination of fluvoxamine (10 microM) and aniline (1 mM) further inhibited the residual POD activity not inhibited by fluvoxamine alone. Microsomal POD activity in 12 human livers in the absence of fluvoxamine was correlated with immunoquantified CYP1A2 levels (r = 0.961, p <.001) and, in the presence of 10 microM fluvoxamine, was correlated with immunoquantified CYP2E1 levels (r = 0.589, p <.01) or chlorzoxazone 6-hydroxylase activity (r = 0.823, p <.001). These results suggest that CYP2E1 is responsible for the low-affinity component of POD in human liver microsomes.

Economic evaluation of alternative indicators for screening for diabetes mellitus

BACKGROUND

the optimal indicator for screening for diabetes mellitus without relying on fasting conditions was clarified.

METHODS

the subjects were 891 men ages 26 through 80 years (48.5 +/- 8.5). The objectives of this study were (1) to elucidate the efficacy of 1,5-anhydroglucitol (1,5-AG), glycosylated hemoglobin, and fructosamine (FRA) as screening tests for non-insulin-dependent diabetes mellitus (NIDDM) or for impaired glucose tolerance (IGT) and (2) to perform an economic evaluation for each indicator. The efficacy of each indicator was evaluated by drawing the receiver operating characteristic curves and calculating the areas under these curves (AUCs). An original model was developed for the pur pose of cost-effectiveness analysis.

RESULTS

each indicator was evaluated as a screening test for NIDDM alone and for both IGT and NIDDM. The AUCs of 1,5-AG and fasting plasma glucose were the largest in the case of the detection of NIDDM alone and the detection of both IGT and NIDDM, respectively. FRA was, however, the most cost-effective in Japan.

CONCLUSION

using equations, we indicated the equi librium points at which the cost-effectiveness ratios of each indicator intersected in order to generalize the results. By calculating the appropriate-actual ratios of costs for each indicator, we could ascertain the optimal indicator for each country.

Sertraline N-demethylation is catalyzed by multiple isoforms of human cytochrome P-450 in vitro

Sertraline, a new antidepressant of the selective serotonin reuptake inhibitor class, is extensively metabolized to desmethylsertraline in humans. We identified the cytochrome P-450 (CYP) isoforms involved in sertraline N-demethylation using pooled human liver microsomes and cDNA-expressed CYP isoforms. Eadie-Hofstee plots for the sertraline N-demethylation in human liver microsomes were monophasic. The estimated Michaelis-Menten kinetic parameters were: KM = 18.1 +/- 2.0 microM, Vmax = 0.45 +/- 0.03 nmol/min/mg of protein, and Vmax/KM = 25.2 +/- 4.3 microl/min/mg of protein. At the substrate concentration of 20 microM, which approximated the apparent KM value, sulfaphenazole (CYP2C9 inhibitor) and triazolam (CYP3A substrate) reduced the N-demethylation activities by 20 to 35% in human liver microsomes, whereas the inhibition induced by mephenytoin (CYP2C19 substrate) or quinidine (CYP2D6 inhibitor) was marginal. The anti-CYP2B6 antibody inhibited the sertraline N-demethylation activities by 35%. Sertraline N-demethylation activities were detected in all cDNA-expressed CYP isoforms studied. In particular, CYP2C19, CYP2B6, CYP2C9-Arg, CYP2D6-Val, and CYP3A4 all showed relatively high activity. When the contributions of CYP2D6, CYP2C9, CYP2B6, CYP2C19, and CYP3A4 were estimated from the Vmax/KM of cDNA-expressed CYP isoforms and from their contents in pooled human liver microsomes, the values were found to be 35, 29, 14, 13, and 9%, respectively. The results suggest that at least five isoforms of CYP (CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4) are involved in the sertraline N-demethylation in human liver microsomes and that the contribution of any individual isoform does not exceed 40% of overall metabolism. Therefore, concurrent administration of a drug that inhibits a specific CYP isoform is unlikely to cause a marked increase in the plasma concentration of sertraline.

Inhibitory effects of azelastine and its metabolites on drug oxidation catalyzed by human cytochrome P-450 enzymes

Azelastine, an antiallergy and antiasthmatic drug, has been reported to be metabolized mainly to desmethylazelastine and 6-hydroxyazelastine in mammals. In the present study, the inhibitory effects of azelastine and its two metabolites on human cytochrome P-450 (CYP) isoform-dependent reactions were investigated to predict the drug interactions of azelastine using microsomes from human B-lymphoblast cells expressing CYP. The specific activities for human CYP isoforms included: 7-ethoxyresorufin O-deethylation (CYP1A1), phenacetin O-deethylation (CYP1A2), coumarin 7-hydroxylation (CYP2A6), 7-benzyloxyresorufin O-dealkylation (CYP2B6), S-warfarin 7-hydroxylation (CYP2C9), S-mephenytoin 4'-hydroxylation (CYP2C19), bufuralol 1'-hydroxylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and testosterone 6beta-hydroxylation (CYP3A4). In almost all the activities, desmethylazelastine exhibited stronger inhibition than azelastine and 6-hydroxyazelastine. Desmethylazelastine, but not azelastine and 6-hydroxyazelastine, uncompetitively inhibited CYP2B6 activity (Ki = 32.6 +/- 4.8 microM). Azelastine, desmethylazelastine, and 6-hydroxyazelastine competitively inhibited CYP2C9 activity (Ki = 13. 9 +/- 1.8, 15.0 +/- 3.1, and 17.0 +/- 4.1 microM, respectively), CYP2C19 activity (Ki = 21.9 +/- 2.2, 7.3 +/- 1.6, and 9.3 +/- 1.6 microM, respectively), and CYP2D6 activity (Ki = 1.2 +/- 0.1, 1.5 +/- 0.2, and 3.0 +/- 0.5 microM, respectively). Azelastine and desmethylazelastine competitively inhibited CYP3A4 activity (Ki = 23. 7 +/- 4.6 and 13.2 +/- 2.3 microM). 6-Hydroxyazelastine interfered with the determination of testosterone 6beta-hydroxylation by HPLC. CYP1A2, CYP2A6, and CYP2E1 activities were not significantly inhibited by azelastine and the two metabolites. Among the human CYPs tested, the inhibitory effects of azelastine and its two metabolites were the most potent on human CYP2D6. In consideration of the Ki values and the concentration of azelastine and desmethylazelastine in human livers after chronic oral administration of azelastine, the possibility of in vivo drug interaction of azelastine and other drugs that are mainly metabolized by CYP2D6 was suggested although it might not cause critical side effects. The inhibition of CYP2C9, CYP2C19, and CYP3A4 activity by azelastine and its two metabolites might be clinically insignificant.

Bacillus thuringiensis insecticidal Cry1Aa toxin binds to a highly conserved region of aminopeptidase N in the host insect leading to its evolutionary success

Bacillus thuringiensis insecticidal protein, Cry1Aa toxin, binds to a specific receptor in insect midguts and has insecticidal activity. Therefore, the structure of the receptor molecule is probably a key factor in determining the binding affinity of the toxin and insect susceptibility. The cDNA fragment (PX frg1) encoding the Cry1Aa toxin-binding region of an aminopeptidase N (APN) or an APN family protein from diamondback moth, Plutella xylostella midgut was cloned and sequenced. A comparison between the deduced amino acid sequence of PX frg1 and other insect APN sequences shows that Cry1Aa toxin binds to a highly conserved region of APN family protein. In this paper, we propose a model to explain the mechanism that causes B. thuringiensis evolutionary success and differing insect susceptibility to Cry1Aa toxin.

[Analysis of the long-term prognosis for conjunctival malignant melanomas in Japan]

PURPOSE

To investigate the long-term prognosis for primary conjunctival malignant melanomas in Japan.

MATERIALS & METHODS

We conducted a survey of 61 cases which had been reported in a 38-year period (1959 to 1996). We gathered information regarding the survival of patients, the post-operative follow-up period, the causes of death, and recurrences. Answers were obtained segarding 51 cases (84%). Detailed progress was identified in 23 of these cases. The survival rates were calculated using the Kaplan-Meier method.

RESULTS

The survival rates were 95.1% after 1 year, 72.9% after 3 years, and 53.4% after 5 years. These values are relatively low compared with those reported in Europe and the United States.

[A case of acute renal failure with rhabdomyolysis caused by the interaction of theophylline and clarithromycin]

Theophylline toxicity has been recognized since its introduction into clinical medicine. Clarithromycin is a new oral macrolide antibiotic with excellent antibacterial activity and rare adverse effect. Patients with upper respiratory infection are often treated with theophylline and clarithromycin concurrently. We report a case of acute renal failure due to acute rhabdomyolysis caused by the interaction of theophylline and clarithromycin. A 72-year-old man visited our hospital because of coughing and a sore throat continuing for 1 week. He was diagnosed as having the common cold with a bronchial asthmatic symptom and was prescribed 200 mg/day of sustained-release theophylline for the treatment of asthma for 7 days. One week later, he visited our hospital again. Radiographic study of the chest revealed mild interstitial pneumonia and 200 mg/day of sustained-release theophylline and 400 mg/day of clarithromycin were administrated concomitantly. Five days after the second visit, the patient was admitted to our hospital because of generalized twitching, muscular weakness, high fever and serious general condition. He experienced generalized muscular twitching and tremor. Blood urea nitrogen was 106.1 mg/dl, serum creatinine was 7.4 mg/dl, serum creatinine kinase (CK) was 36,000 IU/l (normal 15-130 IU/l), CK isozyme revealed the following ratio: BB 0%, MB 1% and MM 99%. He was diagnosed as having acute renal failure with rhabdomyolysis caused by the interaction of theophylline and clarithromycin. Hemodialysis therapy was started. After 5 weeks, his serum creatinine was markedly decreased. It is well-known that clarithromycin enhances the serum concentration of theophylline by inhibition of the cytochrome P450-dependent pathway in hepatocytes. Theophylline toxicity may be enhanced when clarithromycin is administrated concomitantly, especially to elderly patients with dehydration.

Preparation and application of anti-idiotypic antibody against anti-gibberellin A4 antibody

A monoclonal anti-idiotypic antibody was raised against anti-gibberellin A4 (GA4) antibody, which recognizes biologically active gibberellins such as GA1 and GA4 specifically. Amino acid sequences of variable regions of both anti-GA4 and anti-idiotypic antibodies were analyzed. By using the property of the anti-idiotypic antibody to compete with GA1/4 in binding to the anti-GA4 antibody, we successfully applied the anti-idiotypic antibody to ELISA as a tracer for measuring GA1/4. The single-chain Fv (scFv) gene of the anti-idiotypic antibody was constructed, and scFv expressed in E. coli showed binding activity to anti-GA4 antibody. These results suggest the possible application of anti-idiotypic antibody as a handy and stable source of an enzymatic tracer for ELISA by production of fusion protein of the scFv and an appropriate enzyme.

Expression of a functional single-chain antibody against GA24/19 in transgenic tobacco

An anti-gibberellin A24/19 single-chain Fv gene was constructed from gamma and kappa genes cloned from a hybridoma cell line producing monoclonal antibody against gibberellin A24/19, biosynthetic precursors of gibberellin A4/1 which are biologically active per se. The single-chain Fv gene was introduced into tobacco plants after the binding activity of the single-chain Fv expressed in Escherichia coli was confirmed. When the single-chain Fv expression is targeted to endoplasmic reticulum, the plants could accumulate the single-chain Fv protein with the antigen binding activity up to 3.6% of the total soluble protein. On the other hand, when the expression is targeted to cytosol, accumulation of the single-chain Fv protein was not detected at all. The dwarf phenotype of the transgenic plants expressing the single-chain Fv protein, together with the preliminary analytical data indicating a decreased level of gibberellin A1 in the dwarf transgenics, suggested that the single-chain Fv decreased the concentration of bioactive gibberellins by trapping and inhibiting the metabolism of gibberellin A24 and/or A19 to gibberellin A4 and/or A1.

New approach in the evaluation of a fitness program at a worksite

The most common methods for the economic evaluation of a fitness program at a worksite are cost-effectiveness, cost-benefit, and cost-utility analyses. In this study, we applied a basic microeconomic theory, "neoclassical firm's problems," as the new approach for it. The optimal number of physical-exercise classes that constitute the core of the fitness program are determined using the cubic health production function. The optimal number is defined as the number that maximizes the profit of the program. The optimal number corresponding to any willingness-to-pay amount of the participants for the effectiveness of the program is presented using a graph. For example, if the willingness-to-pay is $800, the optimal number of classes is 23. Our method can be applied to the evaluation of any health care program if the health production function can be estimated.

Overexpression of nucleoside diphosphate kinases induces neurite outgrowth and their substitution to inactive forms leads to suppression of nerve growth factor- and dibutyryl cyclic AMP-induced effects in PC12D cells

Whether nucleoside diphosphate kinase (NDPK) is involved in neuronal differentiation was investigated with special reference to its enzyme activity. Neurite outgrowth of PC12D cells induced by nerve growth factor or a cyclic AMP analog was suppressed to some extent when inactive NDPKs (the active site histidine 118 was replaced with alanine), not active forms, were transiently overexpressed. This suppression was more definite in their stably expressed clones. NDPKbeta-transfected clones and, to a lesser extent, NDPKalpha-transfected clones, but not inactive NDPK-transfected clones, extended neurites without differentiation inducers. These results imply that NDPKs may play a role by exerting their enzyme activity during differentiation of PC12 cells.