Characteristics of 3,5,3'-triiodothyronine (T3)-uptake system of tadpole red blood cells: effect of endocrine-disrupting chemicals on cellular T3 response

We characterized the 3,5,3'-L-triiodothyronine (T3)- uptake system on the plasma membrane of Rana catesbeiana tadpole red blood cells (RBCs) in the presence of a variety of inhibitors and potentially competing amino acids. Saturable [125I]T3 uptake was inhibited by phloretin, monodansylcadaverine, bromosulfophthalein, sodium taurocholate and tryptophan. Saturable uptake obeyed simple Michaelis-Menten kinetics with an apparent Km of 110 nM and a Vmax of 2.5 pmol/min per 10(6) cells at 23 degrees C. These results suggested that a large proportion of T3 transported into RBCs was mediated by the aromatic amino acid transporter (System T)-linked transporter. To investigate the effect of endocrine-disrupting chemicals (EDCs) on [125I]T3 uptake, RBCs were incubated with [125I]T3 in the presence of each chemical. Among the test chemicals, di-n-butyl phthalate, n-butylbenzyl phthalate and the miticide, dicofol, were the most powerful inhibitors of [125I]T3 uptake, with an IC50 of 2.2 microM, which was one order of magnitude greater than that for T3 (IC50, 0.14 microM), and diethylstilbestrol and ethinylestradiol were modest inhibitors. Tributyltin accelerated saturable initial [125I]T3 uptake by 2-fold at 3.2 microM. When RBCs were cultured with 10 nM T3 at 25 degrees C for 2 days in the presence of monodansylcadaverine, ethinylestradiol, ioxynil or dicofol at the defined concentrations, these compounds inhibited significantly the induction of the thyroid hormone receptor alpha gene by T3. However, not all chemicals competed with T3 binding to the receptor at the same concentrations. Our results raise the possibility that the T3-uptake system on the plasma membrane of the tadpole RBCs could be a candidate target site for some EDCs and can modulate cellular T3 response.

Current research on acute phase proteins in veterinary diagnosis: an overview

The acute phase proteins (APP) are a group of blood proteins that contribute to restoring homeostasis and limiting microbial growth in an antibody-independent manner in animals subjected to infection, inflammation, surgical trauma or stress. In the last two decades, many advances have been made in monitoring APP in both farm and companion animals for clinical and experimental purposes. Also, the mechanism of the APP response is receiving attention in veterinary science in connection with the innate immune systems of animals. This review describes the results of recent research on animal APP, with special reference to their induction and regulatory mechanisms, their biological functions, and their current and future applications to veterinary diagnosis and animal production.

Detection of corn intrinsic and recombinant DNA fragments and Cry1Ab protein in the gastrointestinal contents of pigs fed genetically modified corn Bt11

Genetically modified corn has been approved as an animal feed in several countries, but information about the fate of genetically modified DNA and protein in vivo is insufficient. Genetically modified corn Bt11 is developed by inserting a recombinant DNA sequence encoding insecticidal Cry1Ab protein from Bacillus thuringiensis subsp. kurstaki. We examined the presence of corn intrinsic and recombinant cry1Ab gene by PCR, and the Cry1Ab protein by immunological tests in the gastrointestinal contents of five genetically modified corn Bt11-fed and five nongenetically modified corn-fed pigs. Fragments of corn zein (242 bp), invertase (226 bp) and of ribulose-1,5-bisphosphate carboxylase/ oxygenase genes (1,028 bp) were detected in the gastrointestinal contents of both Bt11 and nongenetically modified corn-fed pigs. Fragments of recombinant cry1Ab gene (110 bp and 437 bp) were detected in the gastrointestinal contents of the Bt11-fed pigs but not in the control pigs. Neither corn intrinsic nor cry1Ab gene fragments were detected in the peripheral blood by PCR. The gastrointestinal contents were positive for Cry1Ab protein by ELISA, immunochromatography, and immunoblot; however, these methods did not work for blood and precluded conclusions about any potential absorption of the protein. These results suggest that ingested corn DNA and Cry1Ab protein were not totally degraded in the gastrointestinal tract, as shown by their presence in a form detectable by PCR or immunological tests.

Peripapillary crescent enlargement in highly myopic eyes evaluated by fluorescein and indocyanine green angiography

AIMS

To evaluate angiographic features of myopic crescents using fluorescein angiography (FA) and indocyanine green angiography (IA).

METHODS

FA and IA angiograms of 88 highly myopic eyes (47 consecutive patients) were reviewed. The follow up period ranged from 5-28 years.

RESULTS

FA revealed two zones of the myopic crescent: a consistently hypofluorescent inner zone and an outer zone with delayed choroidal filling. IA revealed dislocation of the Zinn-Haller ring to the border between the two zones. Myopic crescent enlargement occurred in 68.1%. Only the outer zone increased significantly in most of the eyes with enlarged crescents.

CONCLUSIONS

The inner zone might develop as a result of mechanical stretching, and the outer zone might be the result a secondary circulatory disturbance and mechanical stretching.

Increased endothelin: nitric oxide ratio is associated with erythropoietin-induced hypertension in hemodialysis patients

Regular administration of recombinant human erythropoietin (rHuEPO) is frequently associated with a rise in arterial blood pressure in hemodialysis (HD) patients. The aim of this study was to examine the effects of rHuEPO on plasma endothelin (ET)-1 and nitric oxide products (NOx) concentration in HD patients. Fifteen patients on maintenance HD with hematocrit of less than 25% were included in the present study. All patients received 3,000 units of rHuEPO intravenously three times a week at the end of each HD session. Plasma levels of ET-1, NOx, thromboxane B2 (TXB2), prostacyclin (6-keto-PGF1alpha), and cyclic guanosine 3',5'-monophosphate (cGMP) were measured before, 2, and 4 weeks after rHuEPO treatment. Plasma concentrations of ET-1, TXB2, and 6-keto-PGF1alpha were measured by radioimmunoassay. Plasma NOx was measured by high-performance liquid chromatography. An rHuEPO-induced increase in mean arterial blood pressure of over 6 mmHg occurred in 7 patients (hypertensive group), whereas the elevation of mean arterial blood pressure was less than 5 mmHg in 8 patients (nonhypertensive group). Plasma ET-1 levels were elevated in all HD patients. Elevated plasma ET-1 levels remained unchanged after rHuEPO treatment in the hypertensive group, whereas the increase in plasma ET-1 levels was attenuated in the nonhypertensive group. Plasma NOx concentrations were also increased in all HD patients. This increase in plasma NOx levels was lessened in the hypertensive group after rHuEPO administration; however, plasma NOx levels remained increased in the nonhypertensive group. Changes in mean arterial blood pressure were significantly correlated with changes in plasma ET-1/NOx ratio. Plasma levels of TXB2, 6-keto-PGF1alpha, and cGMP were unchanged after rHuEPO administration in the hypertensive and nonhypertensive groups. These results suggest that an increase in ET-1/NOx ratio in blood, probably occurring in vascular endothelial cells, may be associated with rHuEPO-induced hypertension in HD patients.

Patchy atrophy and lacquer cracks predispose to the development of choroidal neovascularisation in pathological myopia

AIMS

To determine the incidence and predisposing findings for choroidal neovascularisation (CNV) in a large series of highly myopic patients.

METHODS

The medical records of 218 consecutive patients (325 eyes) with myopic fundus changes in the macula were reviewed. The incidence of CNV during a follow up of at least 3 years of highly myopic patients and identification of predisposing findings for the development of myopic CNV were examined.

RESULTS

Among 325 highly myopic eyes examined, 33 eyes (10.2%) developed myopic CNV. The incidence was higher (34.8%) among the fellow eyes of patients with pre-existing CNV than among eyes of patients without pre-existing CNV (6.1%). CNV developed in 3.7% with diffuse chorioretinal atrophy, in 20.0% with patchy atrophy, and in 29.4% with lacquer cracks.

CONCLUSION

Approximately one in 10 highly myopic eyes developed myopic CNV in average 130.2 months. Patchy atrophy and lacquer cracks were shown to be important predisposing findings for CNV development.

Detection of Cry1Ab protein in gastrointestinal contents but not visceral organs of genetically modified Bt11-fed calves

The fate of insecticidal Cry1Ab protein was examined in the gastrointestinal (GI) contents and visceral organs of calves fed insect-resistant genetically modified maize Bt11. Twelve cross-breed (Japanese black x Holstein) calves were fed either Bt11 or non-genetically modified isoline maize for 90 d. Peripheral blood, rumen juice and feces were collected fortnightly, and GI contents and visceral organs were collected at slaughter at the end of the experiment. Samples were checked for Cry1Ab protein by immunological methods, and visceral organs were examined pathologically. Trace amounts of Cry1Ab protein were detected in the GI contents but not in the liver, spleen, kidney, muscle or mesenteric lymph nodes. No lesions were observed pathologically. Cry1Ab protein in the feces was degraded quickly at atmospheric temperature. These results suggested that only a trace amount of Cry1Ab protein survived passage through the GI tract but was not transferred to liver, spleen, kidney, lymph nodes or muscles.

Structure-activity relationships among zearalenone and its derivatives based on bovine neutrophil chemiluminescence

We compared the effects of zearalenone (ZEN), an estrogenic mycotoxin produced by Fusarium fungi, and its derivatives--a- and b-zearalenols (Zel), zearalanone (ZAN), and a- and b-zearalanols (Zal)--on bovine neutrophils in vitro by using chemiluminescence, a bactericidal parameter. ZEN, a-Zel, and b-Zel suppressed luminol-dependent, phorbol 12-myristate 13-acetate-elicited chemiluminescence at a concentration of 10(-5) M, whereas ZAN, a-Zal and b-Zal did not. The suppressive zearalenols are derived from ZEN through reduction of the C6'-ketone into hydroxide, whereas the non-suppressive ZAN and Zal group possesses a hydrogenated C1'-2' bond in place of the double bond adopted in the macrolide ring or ZEN and the zearalenols. In consideration of these structure-activity relationships among ZEN and its derivatives, we conclude that possession of the C1'-2' double bond is essential for zearalenones to induce neutrophil suppression.

Combination therapy with polymyxin B-immobilized fibre haemoperfusion and teicoplanin for sepsis due to methicillin-resistant Staphylococcus aureus

The aim of the present study was to determine whether treatment with polymyxin B-immobilized fibre (PMX-F) haemoperfusion, teicoplanin, or both in combination is effective in patients with methicillin-resistant Staphylococcus aureus (MRSA) sepsis. Sixty patients with MRSA sepsis were randomly assigned to one of four treatments: (A) PMX-F treatment (N=15), (B) teicoplanin treatment (N=15), (C) PMX-F and teicoplanin in combination (N=20) and (D) conventional therapy (N=10). PMX-F treatment was repeated twice. Teicoplanin was administered by intravenous injection. Plasma endotoxin levels were determined by endospecy test. Plasma endotoxin levels were reduced in groups A and C (P<0.05). Survival rates were 53, 47, 90, and 20% in groups A, B, C and D, respectively (group C versus group A, P<0.05; group C versus group B, P<0.01; group C versus group D,P <0.001). The mean duration of stay was 44, 42, 28 and 56 days in groups A, B, C and D, respectively. Our data suggest that combination therapy with PMX-F and teicoplanin is effective for sepsis caused by MRSA.

Regulation of haptoglobin secretion by recombinant bovine cytokines in primary cultured bovine hepatocytes

We examined the regulation of haptoglobin (Hp) secretion in primary cultured bovine hepatocytes using recombinant bovine (rb) proinflammatory cytokines. The concentrations of Hp in the supernatant of cultured hepatocytes after incubation with rb interleukin (IL)-6, rb tumor necrosis factor (TNF)-alpha, rbIL-1 beta or rbIFN-gamma alone or with combinations of two of these cytokines were measured by ELISA. The rbIL-6, rbTNF-alpha and rbIL-1 beta increased Hp synthesis, but rbIFN-gamma did not, and rbIL-6 was the most effective Hp inducer among these cytokines. The Hp secretion was accelerated synergistically by combined treatment with rbIL-6 and rbTNF-alpha, whereas it remained unchanged with a combination of rbIL-6 and rbIL-1 beta. In contrast, the combination of rbIL-6 and rbIFN-gamma downregulated Hp secretion. In conclusion, IL-6 is the principal cytokine in Hp secretion in bovine hepatocytes in vitro, and its activity may be regulated by other cytokines.

Laparoscopic features of primary biliary cirrhosis in AMA-positive and AMA-negative patients

BACKGROUND AND STUDY AIMS

Antimitochondrial antibody (AMA)-negative primary biliary cirrhosis (PBC) has been difficult to diagnose. Laparoscopic features of AMA-negative PBC were evaluated in comparison with those of AMA-positive PBC and autoimmune hepatitis.

PATIENTS AND METHODS

71 patients who fulfilled the diagnostic criteria for PBC were enrolled in the study; 48 were AMA-positive and 23 were AMA-negative. As a disease control, 46 autoimmune hepatitis patients were included. Both the frequency and specificity of each laparoscopic finding were evaluated. A laparoscopic scoring system was introduced, which used, common and uncommon laparoscopic findings, and was evaluated for the diagnosis of AMA-negative PBC.

RESULTS

The characteristic laparoscopic findings for AMA-positive PBC were yellowish-white marking (92 %), dark-brown discoloration (73 %), gentle undulation (67 %), reddish patch (38 %), and yellowish-white nodules (32 %). On the other hand, laparoscopic findings such as trench-like depression, reddish markings, and wide and small depressions were uncommon in PBC compared with autoimmune hepatitis. The frequencies of characteristic and uncommon laparoscopic findings did not differ statistically between AMA-positive and AMA-negative PBC, but were different between AMA-positive or AMA-negative PBC and autoimmune hepatitis. Scores based on common and uncommon laparoscopic findings were 5.5 +/- 1.5 (mean +/- SD) in AMA-positive PBC, 5.6 +/- 2.0 in AMA-negative PBC, and - 0.30 +/- 0.5 in autoimmune hepatitis.

CONCLUSION

The laparoscopic findings in AMA-negative PBC did not differ from those of AMA-positive PBC. A laparoscopic scoring system may be helpful in the diagnosis of AMA-negative PBC.

Suppressive effect of zearalenone, an estrogenic mycotoxin, on bovine neutrophil chemiluminescence

The effects of zearalenone (ZEA), an estrogenic mycotoxin produced by Fusarium fungi, on bovine neutrophils were investigated in vitro using chemiluninescence, a bactericidal parameter. ZEA suppressed luminol-dependent, phorbol 12-myristate 13-acetate (PMA)-elicited chemiluminescence in a dose-dependent manner at concentrations of 10(-4) M and 10(-5) M. No significant suppression was observed at concentrations lower than 10(-6) M. The possible mode ofaction of 10(-4) M ZEA on the cell activity was investigated with special reference to intracellular Ca2+ ([Ca2+]i) release and estrogen receptors. The 10(-4) M ZEA treatment significantly impaired [Ca2+]i release. When pretreated with a low dose (10(-6) M) of PMA, the cells resisted the ZEA-induced chemiluminescence suppression. However, pretreatment of the cells with the estrogen receptor blockers Tamoxifen and ICl 182,780 (both at 10(-6) M) did not annul the suppressive ZEA action. Considering that PMA is an activator of protein kinase C (PKC), a signal transducing enzyme, and in association with a rise in [Ca2+]i causes cytosolic PKC to shift to the plasma membrane where the activated PKC triggers a varied array of cellular responses, the pharmacological dose of ZEA might have suppressed chemiluminescence by hindering the release of [Ca2+]i and the PKC shift. The results of pretreatment with estrogen receptor blockers, however, did not support the suggestion that the ZEA treatment affected the cells via estrogen receptor pathways.

Comparative effects of plasmapheresis and intravenous cyclophosphamide on urinary podocyte excretion in patients with proliferative Lupus nephritis

Intravenous cyclophosphamide (IVC) in combination with steroids is standard therapy for Lupus nephritis. Reduction of autoantibodies and circulating immune complexes can be used in the treatment of autoimmune diseases. The aim of the present study was to compare the effects of IVC pulse therapy and double-filtration plasmapheresis (DFPP) on proteinuria and urinary excretion of podocytes in adult patients with diffuse proliferative Lupus nephritis (DPLN). Twenty patients were randomly assigned to two groups. Group A (n = 10) was treated with IVC (0.75 - 1.0 g/m2 body surface area) pulse therapy, given as boluses once a month for 6 consecutive months, combined with oral corticosteroid (up to 1 mg/kg/day) administration. Group B (n = 10) was treated with a combination of DFPP (performed 1-2 times weekly) and corticosteroid (up to I mg/kg/ day). The total average number of treatments was 8.4 and the therapeutic efficacies were evaluated after 6 months. Twenty healthy individuals participated as a control group. Urinary podocytes were examined by immunofluorescence with monoclonal antibodies against podocalyxin. Both Group A and Group B reduced proteinuria (p < 0.001) as well as the number of urinary podocytes (p < 0.001). Differences between the 2 treatment outcomes were not statistically significant. Cyclophosphamide pulse therapy and DFPP may be similarly effective in the treatment of podocyte injury in patients with DPLN.

Dual mode recognition of two isoacceptor tRNAs by mammalian mitochondrial seryl-tRNA synthetase

Animal mitochondrial translation systems contain two serine tRNAs, corresponding to the codons AGY (Y = U and C) and UCN (N = U, C, A, and G), each possessing an unusual secondary structure; tRNA(GCU)(Ser) (for AGY) lacks the entire D arm, whereas tRNA(UGA)(Ser) (for UCN) has an unusual cloverleaf configuration. We previously demonstrated that a single bovine mitochondrial seryl-tRNA synthetase (mt SerRS) recognizes these topologically distinct isoacceptors having no common sequence or structure. Recombinant mt SerRS clearly footprinted at the TPsiC loop of each isoacceptor, and kinetic studies revealed that mt SerRS specifically recognized the TPsiC loop sequence in each isoacceptor. However, in the case of tRNA(UGA)(Ser), TPsiC loop-D loop interaction was further required for recognition, suggesting that mt SerRS recognizes the two substrates by distinct mechanisms. mt SerRS could slightly but significantly misacylate mitochondrial tRNA(Gln), which has the same TPsiC loop sequence as tRNA(UGA)(Ser), implying that the fidelity of mitochondrial translation is maintained by kinetic discrimination of tRNAs in the network of aminoacyl-tRNA synthetases.

Effect of cerivastatin on urinary albumin excretion and plasma endothelin-1 concentrations in type 2 diabetes patients with microalbuminuria and dyslipidemia

BACKGROUND/AIMS

To determine whether cerivastatin, a newly developed novel synthetic potent statin, exerts a renoprotective effect, we assessed urinary albumin excretion (UAE) and plasma and urinary endothelin (ET)-1 concentrations in normotensive microalbuminuric type 2 diabetes patients with dyslipidemia.

METHODS

Sixty normotensive type 2 diabetic patients (38 men and 22 women; mean age 56.5 years) with microalbuminuria (20-200 microg/min) and dyslipidemia (total cholesterol >200 mg/dl, LDL cholesterol >160 mg/dl, HDL cholesterol <35 mg/dl, and triglyceride >150 mg/dl) were enrolled in a double-blind study for 6 months, receiving either cerivastatin (0.15 mg/day) or placebo. Plasma and urinary ET-1 concentrations were measured by radioimmunoassay.

RESULTS

Cerivastatin did not affect serum creatinine and HbA(1c) levels, and reduced systolic blood pressure slightly, but not significantly. Plasma levels of total cholesterol and LDL cholesterol were significantly reduced (p < 0.01), and plasma triglyceride levels were also reduced significantly (p < 0.05) after 6 months of cerivastatin treatment. A concomitant significant decrease in UAE (p < 0.01), and urinary and plasma ET-1 concentrations (p < 0.01) were found during this period.

CONCLUSION

The use of cerivastatin is associated with decreased microalbuminuria and plasma and urinary ET-1 levels in microalbuminuric patients with type 2 diabetic mellitus and speculate that this may represent an amelioration of renal injury.

Changes in concentrations of type IV collagen and tissue inhibitor of metalloproteinase-1 in patients with paraquat poisoning

Respiratory failure is one of the major causes of death in patients with paraquat poisoning. In paraquat-poisoned lungs, abnormal extracellular matrix regulation occurs. The aim of the present study is to determine whether serum concentrations of type IV collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) are altered during the course of paraquat poisoning and whether haemoperfusion therapy affects these concentrations. Twenty-one patients were admitted within 3 h after ingestion of paraquat and all patients received direct haemoperfusion therapy. Five out of 21 patients survived and 16 patients died within 28 days. Plasma paraquat concentrations in non-survivors (5740 +/- 380 microg l(-1)) were not significantly different from those in survivors ( 5920 +/- 280 microg l(-1)) before treatment. Haemoperfusion reduced these concentrations in both non-survivors (120 +/- 7 microg l(-1)) as well as survivors (136 +/- 9 microg l(-1)) on day 5. Serum concentrations of type IV collagen and TIMP-1 in survivors showed little change between day 1 (type IV collagen, 90.4 +/- 3.6 ng ml(-1); TIMP-1, 172.2 +/- 7.0 ng ml(-1)) and day 5 (type IV collagen, 92.6 +/- 4.2 ng ml(-1); TIMP-1, 174.2 +/- 7.2 ng ml(-1)). In contrast, these concentrations in non-survivors on day 5 (type IV collagen, 143.6 +/- 7.8 mg ml(-1); TIMP-1, 246.8 +/- 13.6 ng ml(-1)) were significantly higher than those on day 1 (type IV collagen, 88.4 +/- 4.2 ng ml(-1), P < 0.01; TIMP-1, 170.6 +/- 9.2 ng ml(-1), P < 0.05). These data suggest that serum concentrations of type IV collagen and TIMP-1 may be useful indicators for the development of respiratory failure in patients with paraquat poisoning.

Pioglitazone reduces urinary podocyte excretion in type 2 diabetes patients with microalbuminuria

In various renal diseases, including diabetic nephropathy, detection of podocytes in the urine indicates severe injury to podocytes in the glomeruli. Pioglitazone is a newly developed antidiabetic agent that attenuates insulin resistance. The aim of the present study was to determine whether pioglitazone affects urinary albumin excretion (UAE) or the number of urinary podocytes or both in type 2 diabetes patients with microalbuminuria. Twenty-eight patients with normotensive type 2 diabetes and microalbuminuria (18 men and 10 women; mean age, 52.5 years) and 30 age-matched normotensive controls (20 men and 10 women; mean age, 51.5 years) were included in the study. Urinary podocytes were detected by immunofluorescence with a monoclonal antibody against podocalyxin. Patients were randomly assigned to 2 groups: a pioglitazone-treatment group (30 mg/day, n = 14) and a placebo group (n = 14). Treatment was continued for 6 months. Podocytes were absent in the urine of healthy controls, but detected in 17 of 28 diabetic patients (60.7%). UAE was reduced from 96.7 +/- 50.5 microg/min to 39.7 +/- 22.9 microg/min (P <.01) in the pioglitazone-treatment group, and the number of urinary podocytes was reduced from 0.9 +/- 1.0 cells/mL to 0.1 +/- 0.2 cells/mL (P <.001). Neither UAE nor the number of urinary podocytes was affected in the placebo group. These data indicate that pioglitazone is effective for reducing UAE and podocyte injury in early-stage diabetic nephropathy.

Alterations of gene expression in endoderm differentiation of F9 teratocarcinoma cells

During the endoderm differentiation of F9 mouse embryonal carcinoma cells, as induced by sodium butyrate (NaBu) or retinoic acid (RA), gene expressions of alkaline phosphatase (ALPase), pyruvate kinase (PKase) and 5' ribonucleotide phosphohydrolase (5'-Nase) were examined. The specific activity of ALPase was found to increase by 3.5-fold after 48 hr treatment with NaBu. In contrast, specific activity of PKase were decreased by 63%. Northern blot analysis revealed that the elevation of ALPase activity resulted from an increase in the level of liver/bone/kidney (L/B/K)-type ALPase mRNA and that the decrease of PKase activity was dependent on a reduction in the level of M(2)-PKase mRNA. Interestingly, when NaBu was removed from the culture medium, the levels of these mRNAs reverted to their original levels after 16 h. During these processes, the specific activity of 5'-Nase and the level of its mRNA remained unchanged. In contrast, when F9 cells were treated with RA, only the level of L/B/K-type ALPase mRNA increased. Lastly, we examined the issue of whether an increase in the level of ALPase mRNA is dependent on the transcriptional activation of the mouse L/B/K-type ALPase gene. Transient transfection assays using luciferase reporter constructs showed that the promoter activity increased as the result of treatment with RA but not with NaBu.

Inhibition and inactivation of human cytochrome P450 isoforms by phenethyl isothiocyanate

The inhibition and mechanism-based inactivation potencies of phenethyl isothiocyanate (PEITC) for human cytochrome P450 (CYP) activities were investigated using microsomes from baculovirus-infected insect cells expressing specific human CYP isoforms. PEITC competitively inhibited phenacetin O-deethylase activity catalyzed by CYP1A2 (K(i) = 4.5 +/- 1.0 microM) and coumarin 7-hydroxylase activity catalyzed by CYP2A6 (K(i) = 18.2 +/- 2.5 microM). Benzyloxyresorufin O-dealkylase activity catalyzed by CYP2B6 was most strongly and noncompetitively inhibited (K(i) = 1.5 +/- 0.0 microM). Paclitaxel 6alpha-hydroxylase activity catalyzed by CYP2C8 was not affected by PEITC up to 100 microM. PEITC noncompetitively inhibited S-warfarin 7-hydroxylase activity catalyzed by CYP2C9 (K(i) = 6.5 +/- 0.9 microM), S-mephenytoin 4'-hydroxylase activity catalyzed by CYP2C19 (K(i) = 12.0 +/- 3.2 microM), bufuralol 1'-hydroxylase activity catalyzed by CYP2D6 (K(i) = 28.4 +/- 7.9 microM), and chlorzoxazone 6-hydroxylase activity catalyzed by CYP2E1 (K(i) = 21.5 +/- 3.4 microM). The inhibition for testosterone 6beta-hydroxylase activity catalyzed by CYP3A4 was a mixed-type of competitive (K(i) = 34.0 +/- 6.5 microM) and noncompetitive (K(i) = 63.8 +/- 12.5 microM) inhibition. Furthermore, PEITC is a mechanism-based inactivator of human CYP2E1. The k(inact) value was 0.339 min(-1) and K(i) was 9.98 microM. Human CYP1A2, CYP2A6, CYP2B6, CYP2D6, and CYP3A4 were not inactivated. The present study directly proved that the chemopreventive effects of PEITC for nitrosamine-induced carcinogenesis are due to the inhibition of CYP by an in vitro study. The possibility that PEITC would affect the pharmacokinetics of clinically used drugs that are metabolized by these CYP isoforms was also suggested.

Re-evaluation of the latent period of bladder cancer in dyestuff-plant workers in Japan

BACKGROUND

The carcinogenesis of benzidine (BZ) and beta-naphthylamine (BNA) for bladder is well known. Although it was thought to be rare to develop occupational bladder cancer more than 20 years after the exposure to these chemicals, there are still new clinical cases even 30 years after exposure. The purpose of this study was to re-evaluate the latent carcinogenic period of BZ and BNA, in order to set the safety period after exposure for the health surveillance system.

METHODS

The subjects were 236 dyestuff-plant workers in Tokyo, who had been exposed to these dyestuffs. The incidence of bladder cancer and its histopathology in this group was surveyed in the period from 1962 to 1996.

RESULTS

Nineteen workers (8.1%) were found to have bladder cancers. The exposure period for these 19 patients was 82.0 +/- 50.2 months. The mean +/- SD latent period from the subjects' initial and final exposure until tumor development was 29.5 +/- 8.2 years and 20.1 +/- 10.6 years, respectively. Significantly, a negative correlation (Pearson) was observed between the exposure period and the latent period from the end of exposure to cancer onset (R = -0.544, P < 0.05). All tumors except one were transitional cell carcinoma. Flow cytometric analysis was performed in 11 patients and all of these patients had DNA aneuploidy.

CONCLUSIONS

The latent periods of bladder cancer caused by BZ and BNA were longer than previously expected. It is necessary to survey the onset of bladder cancer in exposed workers more than 30 years after the initial exposure.

T cell repertoire in primary biliary cirrhosis: a common T cell clone and repertoire change after treatment

T cell repertoire was analyzed in three early-stage primary biliary cirrhosis (PBC) patients, using reverse transcription-polymerase chain reaction and single-strand conformation polymorphism. Multiple expanded clones were demonstrated in livers and peripheral blood lymphocytes (PBL) of all three patients. Comparison of the repertoire of different parts of the liver demonstrated the presence of common clones in various Vbeta families. Comparison of the repertoire between the liver and PBL demonstrated that both CD4 and CD8 T cell clones were expanded. Sequence analysis of complementarity determining region 3 of the expanded clones revealed that relatively conserved amino acids were utilized in each patient and that an identical CD4 T cell clone having Vbeta16 was present in all three patients. The number of expanded T cell clones in PBL decreased markedly after the treatment with prednisolone. These results suggest that common T cell clones may play a pathogenic role in PBC.

Kinetics of testosterone 6beta-hydroxylation in the reconstituted system with similar ratios of purified CYP3A4, NADPH-cytochrome p450 oxidoreductase and cytochrome B5 to human liver microsomes

Kinetics of testosterone 6beta-hydroxylation were determined using a reconstituted system that consisted of CYP3A4, cytochrome b5 and NADPH-cytochrome P450 oxidoreductase (OR) with similar ratios as those seen in human liver microsomes and compared with those determined using human liver microsomes. Two reconstituted systems were constructed in accordance with two human liver microsomal samples that showed extremely high and low ratios of OR/CYP3A4. The Km values of testosterone 6beta-hydroxylation obtained from the reconstituted systems with high and low OR/CYP3A4 ratios were 29.3 and 35.2 microM, respectively, which were similar to that of the corresponding human liver microsomal samples (23.2 and 40.0 microM, respectively). However, Vmax values obtained from the reconstituted systems (3.7 and 0.8 pmol/min/pmol CYP3A4) were much lower than those from the human liver microsomes (44.2 and 31.1 pmol/min/pmol CYP3A4). The results suggest that the interaction between substrate and CYP3A4 in the reconstituted systems appear to be similar to human liver microsomes but that the velocity of the substrate metabolism in the reconstituted systems is different from that in human liver microsomes. In conclusion, our reconstituted systems could be used for the determination of affinity but not for the determination of the maximum velocity of substrate metabolism. Further studies on the protein-protein interactions between CYP3A4, OR, cytochrome b5 and/or a specific lipid environment are required to establish a reconstituted system showing similar kinetic properties to those of human liver microsomes.