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Biomedical subjects

T Inaba

Publications and source records attributed to T Inaba.

At least 127 records · Page 7Linked to original sources

Cytokine-stimulated release of decay-accelerating factor (DAF;CD55) from HT-29 human intestinal epithelial cells.

Expression of DAF (CD55) is enhanced on colonic epithelial cells of patients with ulcerative colitis (UC), and stool DAF concentrations are increased in patients with active disease. Cytokines are known to modulate DAF expression in various human cells, and lesions of UC reveal altered profiles of cytokine production. In this study, we evaluate the effects of various cytokines, IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, and interferon-gamma (IFN-gamma), on the synthesis and kinetics of DAF protein in HT-29 human intestinal epithelial cells. Using flow cytometry and an ELISA, we found that HT-29 cells constitutively express DAF on the cell surface and spontaneously release DAF into the culture supernatant under standard culture conditions. When the culture supernatant was centrifuged at 100000g, nearly a half of DAF was precipitated, indicating that one half of the released DAF was present as a membrane-bound form and the other half as a soluble form. Analysis of the culture supernatant of biotin surface-labelled HT-29 cells suggested that the soluble form DAF was derived by secretion from within the cell or by cleavage from the cell surface. Among the cytokines, IL-4 markedly, and IL-1beta moderately, enhanced the expression and the release of DAF. Actinomycin D, cycloheximide, and brefeldin A inhibited the increase in DAF release induced by IL-4 and IL-1beta stimulation. These results suggest that DAF is released from intestinal epithelial cells in response to cytokine stimulation and that IL-4 and IL-1beta are possible cytokines involved in DAF release into the colonic lumen of patients with UC.

Anti-Bacterial Agents↗

Trimethadione metabolism by human liver cytochrome P450: evidence for the involvement of CYP2E1.

1. Caucasian liver samples were used in this study. N-demethylation of trimethadione (TMO) to dimethadione (DMO) was monitored in the presence of chemical inhibitors of CYPs, such as fluconazole, quinidine, dimethyl-nitrosamine, acetaminophen, phenacetin, chlorzoxazone and mephenytoin. Trimethadione N-demethylation was selectively inhibited by dimethylnitrosamine and chlorzoxazone (> 50%) and weakly inhibited by tolbutamide (12%) and fluconazole (22%), whereas other inhibitors showed no effect. This result suggested that TMO metabolism to DMO is mainly mediated by CYP2E1 and marginally by CYP2C and CYP3A4. 2. Fifteen human livers were screened and interindividual variability of TMO N-demethylation activity was 3-fold. Chlorzoxazone 6-hydroxylation activity was also measured and both activities were significantly correlated (r=0.735, p < 0.01). 3. DMO production by human cDNA expressed CYP enzymes was observed mainly for CYP2E1 (10.8 nmol/tube), marginally for CYP2C8 (0.22 nmol/tube) and not detectable for other CYP enzymes. 4. These results indicate that TMO metabolism is primarily catalysed by CYP2E1 and that trimethadione would be a suitable selective probe drug for the estimation of human CYP2E1 activity in vivo.

Anticonvulsants↗

Effects of growth hormone and insulin-like growth factor I on opsonin receptor expression on local and systemic phagocytes in a lethal peritonitis model.

OBJECTIVE: To investigate the effects of pretreatment with growth hormone (GH) and insulin-like growth factor I (IGF-I) on phagocyte exudation and bacterial clearance, focusing on CD11b and CD32/CD16 expression on local and systemic phagocytes, in a lethal peritonitis model. DESIGN: Prospective randomized experimental study. SETTING: Research laboratory in a university hospital. SUBJECTS: Balb/c mice (n = 21). INTERVENTIONS: Mice were challenged intraperitoneally with 1 x 10(8) Escherichia coli, after 6 days of pretreatment with saline (control), GH (4.8 mg/kg/day), or IGF-I (24 mg/kg/day). Samples were harvested at 4 hrs after the challenge. MEASUREMENTS AND MAIN RESULTS: Viable bacterial counts in peritoneal lavage fluid (PLF) and blood were determined. Peritoneal exudative cells and peripheral blood leukocytes were counted and analyzed for receptor expressions by flow cytometry. GH reduced viable bacterial counts in PLF, as compared with the saline control. GH (three-fold) and IGF-I (two-fold) increased the number of peritoneal exudative neutrophils (PENs), as compared with the saline control. The number of PENs showed an inverse correlation with PLF viable bacterial counts. By contrast, there were no differences in peripheral blood neutrophil (PN) counts among the three groups, nor was there a correlation between PN and PEN counts. CD11b expression was greater on PENs than on PNs in all three groups. CD11b expression on PNs did not differ among the three groups. However, GH increased CD11b expression on PENs, as compared with saline and IGF-I, and this expression showed a positive correlation with PEN numbers and an inverse correlation with PLF viable bacterial counts. CD11b expression on peritoneal macrophages and peripheral blood monocytes did not differ among the three groups. There were no differences in phagocyte CD32/CD16 expression among the three groups. CONCLUSIONS: GH pretreatment enhanced CD11b expression on PENs, but not PNs, possibly in association with enhanced neutrophil recruitment, phagocytosis, and bacterial elimination by PENs, without activation of PNs. GH prophylaxis may be useful for reducing the frequency rate and severity of septic complications, via modulation of CD11b expression on local and systemic neutrophils.

Animals↗

FLT-3 ligand mobilizes hematopoietic primitive and committed progenitor cells into blood in mice.

We investigated the effects of the administration of FLT-3 ligand (FL) on mobilization of primitive and committed progenitor cells in mice. C57bl/6J mice were injected subcutaneously with FL once a day for 5 d at doses of 20, 100 and 200 microg/kg. After the collection of peripheral blood, we determined the number of white blood cells (WBCs) with the differential counts. The formation of colony-forming cells (CFCs) in peripheral blood, bone marrow and spleen was evaluated. Although the administration of FL, 20 microg/kg, did not stimulate leukocytosis, its administration at doses of 100 and 200 microg/kg increased the number of WBC up to 1.7- and 2.4-fold, respectively. Committed progenitor cells were mobilized into the peripheral blood dose-dependently and the number of CFCs was increased up to 5.5-fold by the administration of FL at 200 microg/kg on d 5. The number of CFCs in the bone marrow increased, but not dose-dependently. The number of CFCs in the spleen also increased up to 32-fold at a dose of 200 microg/kg FL. Mobilized peripheral blood mononuclear cells were transplanted into lethally irradiated mice and the number of CFU-S (d 12) was scored. A dose-dependent mobilization of CFU-S (d 12) into peripheral blood was also observed. These observations suggest that FL can mobilize hematopoietic primitive and committed progenitor cells into the peripheral blood of mice and those cells mobilized by FL may be applicable to peripheral blood stem cell transplantation.

Animals↗

Carbonyl reduction of timiperone in human liver cytosol.

This in vitro study using human liver enzymes was undertaken in order to compare the mechanism of metabolic reduction of timiperone, a potent butyrophenone neuroleptic, with that of haloperidol. Conversion of timiperone to reduced timiperone in liver cytosol was confirmed. The carbonyl reductase inhibitors (menadione IC50 5-18 microM; ethacrynic acid IC50 26-51 microM) potently inhibited both timiperone reductase and haloperidol reductase activity, while 4-methylpyrazole (alcohol dehydrogenase inhibitor) had no effect and phenobarbital (aldehyde reductase inhibitor) had a weak inhibitory effect. The formation of reduced timiperone was highly correlated with the formation of reduced haloperidol(r = 0.87, n = 6, P < 0.02). Timiperone reductase activity was approximately 40% lower than haloperidol reductase activity (at a substrate concentration of 100 microM, two-tailed t-test, P < 0.05). The Michaelis-Menten constant (Km) and maximum velocity (Vmax) of reduced timiperone formation were much lower than reduced haloperidol formation (K(m) values: 29.7 +/- 15.1 versus 381.3 +/- 1.1 microM, n = 3, P < 0.01; Vmax: 0.81 +/- 0.19 versus 6.00 +/- 1.47 nmol/mg/min; n = 3, P < 0.05). However, the ratio Vmax/K(m) (clearance) for timiperone was 1.3-2.4 times higher than for haloperidol, indicating that metabolic clearance of timiperone by carbonyl reductase may be similar to or slightly higher than for haloperidol.

Alcohol Oxidoreductases↗

Zidovudine azido-reductase in human liver microsomes: activation by ethacrynic acid, dipyridamole, and indomethacin and inhibition by human immunodeficiency virus protease inhibitors.

AZT (zidovudine, 3'-azido-3'-deoxythymidine), although metabolized primarily to AZT-glucuronide, is also metabolized to 3'-amino-3'-deoxythmidine (AMT) by reduction of the azide to an amine. The formation of the myelotoxic metabolite AMT has not been well characterized, but inhibition of AMT formation would be of therapeutic benefit. The aim of this study was to identify compounds that inhibit AMT formation. Using human liver microsomes under anaerobic conditions and [2-14C]AZT, K(m) values of AZT azido-reductase, estimated by radio-thin-layer chromatography, were 2.2 to 3.5 mM (n = 3). Oxygen completely inhibited this NADPH-dependent reduction. Thirteen of the 28 compounds tested inhibited the formation of AMT. In addition to the CYP3A4 inhibitors ketoconazole, fluconazole, indinavir, ritonavir, and saquinavir, metyrapone strongly inhibited AMT formation. An unexpected finding was the more-than-twofold increase in AMT formation in the presence of ethacrynic acid, dipyridamole, or indomethacin. Such activation of toxic metabolite formation would impair drug therapy.

Chromatography, Thin Layer↗

The AD1 and AD2 transactivation domains of E2A are essential for the antiapoptotic activity of the chimeric oncoprotein E2A-HLF.

The chimeric oncoprotein E2A-HLF, generated by the t(17;19) chromosomal translocation in pro-B-cell acute lymphoblastic leukemia, incorporates the transactivation domains of E2A and the basic leucine zipper (bZIP) DNA-binding and protein dimerization domain of HLF (hepatic leukemic factor). The ability of E2A-HLF to prolong the survival of interleukin-3 (IL-3)-dependent murine pro-B cells after IL-3 withdrawal suggests that it disrupts signaling pathways normally responsible for cell suicide, allowing the cells to accumulate as transformed lymphoblasts. To determine the structural motifs that contribute to this antiapoptotic effect, we constructed a panel of E2A-HLF mutants and programmed their expression in IL-3-dependent murine pro-B cells (FL5.12 line), using a zinc-inducible vector. Neither the E12 nor the E47 product of the E2A gene nor the wild-type HLF protein was able to protect the cells from apoptosis induced by IL-3 deprivation. Surprisingly, different combinations of disabling mutations within the HLF bZIP domain had little effect on the antiapoptotic property of the chimeric protein, so long as the amino-terminal portion of E2A remained intact. In the context of a bZIP domain defective in DNA binding, mutants retaining either of the two transactivation domains of E2A were able to extend cell survival after growth factor deprivation. Thus, the block of apoptosis imposed by E2A-HLF in pro-B lymphocytes depends critically on the transactivating regions of E2A. Since neither DNA binding nor protein dimerization through the bZIP domain of HLF is required for this effect, we propose mechanisms whereby protein-protein interactions with the amino-terminal region of E2A allow the chimera to act as a transcriptional cofactor to alter the expression of genes regulating the apoptotic machinery in pro-B cells.

Animals↗

Changes of hepatic tissue phospholipid peroxidation, malondialdehydes, and antioxidative enzyme activities in dogs with halothane inhalation.

To elucidate the pathogenesis of halothane-induced hepatopathy, the changes of hepatic tissue phospholipid peroxidation, malondialdehydes (MDAs), and antioxidative enzyme activities were examined in the portal vein arterialized dogs with halothane inhalation. In group A, which was given halothane inhalation under the hepatic blood flow volume less than 10% of pre-operation volume designated as a hypoxic condition, peroxidized phosphatidylcholine (PC), and free and protein-bound MDA levels significantly increased after inhalation. Although the level of protein bound MDA in group C, given hypoxic condition alone, also increased during the experimental period, the response of this was smaller than that in group A, suggesting that the halothane inhalation enhanced free radical generation under the hypoxic condition. In contrast, no significant changes of these levels were observed in groups B and D, both of which were supplied with sufficient hepatic oxygen as the normoxic condition. In addition, the significant negative correlations between hepatic oxygen supply and total or protein-bound MDA were observed in only halothane inhaled group. These findings suggested that the cause of halothane-induced hepatopathy is closely related to free radicals mainly generated from halothane anaerobic metabolism under the hypoxic condition.

Administration, Inhalation↗

A progesterone antagonist cannot prevent fetal survival if the uterine horn is incised.

The fetuses released into the abdominal cavity by uterine incision escape from most physical influences of the uterus. This study examined whether these fetuses require progesterone actions for survival during late pregnancy in rats. A longitudinal incision in one uterine horn (with the other horn intact) together with bilateral ovariectomy (OVX), removal of the main progesterone-production sites, or sham OVX, were performed on day 18 of pregnancy. Thereafter the rats were given daily subcutaneous injections of anti-progesterone RU 486 (10 mg/kg), or vehicle alone, and the fetal survival rate in each uterine horn was examined on day 21. In those controls which received sham OVX plus injections of vehicle, fetal survival rates were more than 80% in both uterine horns. In the other groups, which received sham OVX plus injections of RU 486, or OVX plus injections of vehicle, or OVX plus injections of RU 486, the fetal survival rates in the intact uterine horns were 4%, 0% and 0%, respectively. In the incised uterine horns of these groups, however, the fetal survival rates were 59%, 67% and 56%, respectively. The results suggest that progesterone, which is required for maintaining pregnancy, may not be essential for survival of fetuses released into the abdominal cavity. Progesterone actions unrelated to uterine physical environment are likely to be dispensable for fetal survival during late pregnancy in rats.

Animals↗

Immunization of laboratory animals with ultraviolet-attenuated larvae against homologous challenge infection with Trichinella britovi.

Immunogenicity of Trichinella britovi (Japanese isolate, cord ISS 408) muscle larvae irradiated with 5 mJ/cm2 of short wavelength ultraviolet (UV) was studied using homologous challenge infections. SCID mice vaccinated with UV-attenuated larvae showed no resistance, although its congenic CB-17 mice exhibited remarkable immunity. Following challenge vaccinated Mongolian gerbils, Meriones unguiculatus, did not show significant immunity. Use of these animal models vaccinated with UV-attenuated larvae will contribute to the investigation of immune mechanisms against Trichinella infection and also to the development of a vaccine of trichinellosis.

Animals↗

[The predictor for platelet recovery after PBSCT].

OBJECTIVE: In order to find out a predictor more accurate, reliable and convenient for platelet recovery capacity after peripheral blood stem cell transplantation (PBSCT). METHODS: The number of megakaryocyte progenitor cells in PBSC grafts of 17 patients with hematological malignancies or solid tumors was measured by clonogenic (CFU-MK) and flow cytometric assays. RESULTS: 1. The expression of platelet membrane glycoprotein was on < 5% of CD34+ cells. 2. The time needed for platelet recovery was better correlated with the number of CD34+/CD41a+ cells than with the total number of CD34+ cells. 3. There was a close correlation between the number of CFU-MK and the time needed for platelet recovery. 4. Correlation was observed between the number of CD34+/CD41a+ cells and that of CFU-MK. CONCLUSION: The numbers of CD34+/CD41a+ cells and CFU-MK are predictors for platelet recovery after PBSCT, but the former may be a more convenient and reliable marker for clinical study.

Adolescent↗

N-Dealkylation and hydroxylation of ebastine by human liver cytochrome P450.

Ebastine [4'-tert-butyl-4-[4-(diphenylmethoxy)piperidino]butyro phe- none] is a new-generation, nonsedative, H1 antihistamine. The present study was performed to characterize the cytochrome P450 (CYP) isoforms responsible for ebastine N-dealkylation and hydroxylation. Human liver microsomes metabolized ebastine to two major metabolites, i.e. a desbutyrophenone metabolite (des-BP) and hydroxyebastine (M-OH), and the ratio of Vmax values was 3:1. N-Dealkylation yielded des-BP, whereas M-OH, an hydroxylation product, could be further oxidized to the pharmacologically active carebastine. In a panel of 14 human liver microsomal preparations, the rate of dealkylation showed a highly significant correlation with CYP3A-mediated testosterone 6beta-hydroxylation but not with reactions of seven other CYP isoforms. However, there was no correlation between the two pathways for ebastine (dealkylation and hydroxylation). Differential chemical inhibition in liver microsomes, in which dealkylation was more sensitive than hydroxylation, was demonstrated with ketoconazole, troleandomycin, cyclosporin A, and midazolam. Anti-CYP3A antibodies markedly reduced the dealkylation rate (>95%) in liver microsomes but exhibited insignificant effects on hydroxylation (<5%). Among 12 cDNA-expressed human CYP isoforms, which account for up to 70% of the total CYP enzyme content in human liver, CYP3A4 alone metabolized ebastine; the ratio of des-BP to M-OH formation was 12:1. This ratio for metabolism by the pure enzyme was much larger than the ratio (3:1) observed for the microsomal reaction mixture. This change in ratio, which is attributed to a decrease in M-OH formation, indicates that, although ebastine is metabolized to two major metabolites, N-dealkylation to des-BP is mediated by CYP3A, whereas hydroxylation to M-OH appears to be mediated mainly by unidentified enzymes other than CYP3A.

Butyrophenones↗

[Invasive thymoma successfully treated with high-dose chemotherapy followed by peripheral blood stem cell transplantation(PBSCT)].

A 42-year-old man was admitted with chest pain. A large mass in the anterior mediastinum was seen on a chest X-ray film and confirmed by CT. Surgery was performed, but the tumor was nonresectable because it had invaded the aorta and pulmonary artery, and had disseminated to the pericardium. Invasive thymoma (stage IVa) was diagnosed He initially received two courses of ADOC (50 mg/m2 of cisplatin, 40 mg/m2 of doxorubicin, 0.6 mg/m2 of vincristine, and 700 mg/m2 of cyclophosphamide) at 3-week intervals. Four weeks after the 2 causes of ADOC, he was given 300 mg/m2 of etoposide for five days followed by G-CSF subcutaneously for peripheral blood stem cell collection. After the two courses of ADOC, he received high-dose ICE (1.5 g/m2 of ifosfamide for four days, 400 mg/m2 of carboplatin for three days, and 200 mg/m2 of etoposide for five days) followed by peripheral blood stem cell transplantation (PBSCT). He was given G-CSF after PBSCT, with subsequent rapid neutrophil and platelet recovery. The tumor diminished remarkably in size and complete remission was confirmed pathologically at subsequent thoractomy. Postoperatively, 50 Gy of irradiation was given. These observations suggest that high-dose ICE followed by PBSCT in combination with an ADOC regimen, surgery, and radiotherapy is highly effective and well tolerated in patients with advanced nonresectable thymoma.

Adult↗

[Myelodysplastic syndrome (RAEB in T) developed in a renal allograft recipient].

A 46-year-old man who had been treated with azathioprine (150 mg/day) and prednisolone (7.5-10 mg/day) for 16 years after allogeneic renal transplantation was admitted to our hospital in July 1996 for evaluation of pancytopenia. Three years earlier he had been given a diagnosis of renal pelvic and ureteral cancer, and underwent left nephrectomy with total uretectomy. His bone marrow was normocellular with excess of blasts (27.6%), and displayed trilineage myelodysplasia. A chromosomal analysis of the bone marrow revealed 43-45, XY with del (1) (p13), -5, del (7) (q22), -17, -18, and -19. The patient was given a diagnosis of refractory anemia with excess of blasts in transformation (RAEB in T), and treated with idarubicin and cytosine arabinoside. Two months later, overt acute leukemia developed and reinduction chemotherpay was started, but the patient died of cerebral hemorrhage in October. This case suggests that immunosuppressive agents such as azathioprine might play an important role in the pathogenesis of MDS (RAEB in T) and renal pelvic and ureteral cancer after renal transplantation.

Anemia, Refractory, with Excess of Blasts↗

Use of EBV-based Vector/HVJ-liposome complex vector for targeted gene therapy of EBV-associated neoplasms.

Targeted suicide gene therapy for Epstein-Barr virus (EBV)-associated neoplasms was attempted by using EBV-based plasmid vectors coupled with hemagglutinating virus of Japan (HVJ)-liposome in vitro. Expression of EBV nuclear antigen (EBNA)1 is a common feature of the neoplasms associated with EBV. When various leukemic cell lines were transduced with a vector carrying a marker gene and EBV replication origin of plasmid (oriP), the marker gene product was exclusively detected in cells expressing EBNA1. Transduction of herpes simplex virus (HSV)-1 thymidine kinase (Tk) gene resulted in a marked reduction in viable cell number by ganciclovir (GCV) specifically in EBNA1 positive cells. The results demonstrate that this virus-free system may be applicable to gene therapy of EBV-associated neoplasms.

Antiviral Agents↗

Development of a novel selective amplifier gene for controllable expansion of transduced hematopoietic cells.

To overcome the low efficiency of gene transfer into hematopoietic cells, we developed a novel system for selective expansion of transduced cells. To this end, we constructed a chimeric cDNA (GCRER) encoding the fusion protein between the granulocyte colony-stimulating factor receptor (G-CSFR) and the hormone-binding domain (HBD) of the estrogen receptor (ER) as a selective amplifier gene. Use of the intracellular signaling pathway of G-CSFR was considered to be appropriate, because G-CSF has the ability not only to stimulate the neutrophil production, but also to expand the hematopoietic stem/progenitor cell pool in vivo. To activate the exogenous G-CSFR signal domain selectively, the estrogen/ER-HBD system was used as a molecular switch in this study. When the GCRER gene was expressed in the interleukin-3 (IL-3)-dependent murine cell line, Ba/F3, the cells showed IL-3-independent growth in response to G-CSF or estrogen. Moreover, the Ba/F3 cells transfected with the Delta(5-195)GCRER, whose product lacks the extracellular G-CSF-binding domain, did not respond to G-CSF, but retained the ability for estrogen-dependent growth. Further, murine bone marrow cells transduced with the GCRER or Delta(5-195)GCRER gene with retroviral vectors formed a significant number of colonies in response to estrogen, as well as G-CSF, whereas estrogen did not stimulate colony formation by untransduced murine bone marrow cells. It is noteworthy that erythroid colonies were apparently formed by the bone marrow cells transduced with the GCRER gene in the presence of estrogen without the addition of erythropoietin, suggesting that the signals from the G-CSFR portion of the chimeric molecules do not preferentially induce neutrophilic differentiation, but just promote the differentiation depending on the nature of the target cells. We speculate that when the selective amplifier genes are expressed in the primitive hematopoietic stem cells, the growth signal predominates and that the population of transduced stem cells expands upon estrogen treatment, even if some of the cells enter the differentiation pathway. The present study suggests that this strategy is applicable to the in vivo selective expansion of transduced hematopoietic stem cells.

Animals↗

Interactions of amphetamine analogs with human liver CYP2D6.

The interaction of fifteen amphetamine analogs with the genetically polymorphic enzyme CYP2D6 was examined. All fourteen phenylisopropylamines tested were competitive inhibitors of CYP2D6 in human liver microsomes. The presence of a methylenedioxy group in the 3,4-positions of both amphetamine (Ki = 26.5 microM) and methamphetamine (Ki = 25 microM) increased the affinity for CYP2D6 to 1.8 and 0.6 microM, respectively. Addition of a methoxy group to amphetamine in the 2-position also increased the affinity for CYP2D6 (Ki = 11.5 microM). The compound with the highest affinity for CYP2D6 was an amphetamine analog (MMDA-2) having both a methoxy group in the 2-position and a methylenedioxy group (Ki = 0.17 microM). Mescaline did not interact with CYP2D6. O-Demethylation of p-methoxyamphetamine (PMA) by CYP2D6 was characterized (Km = 59.2 +/- 22.4 microM, and Vmax = 29.3 +/- 16.6 nmol/mg/hr, N = 6 livers). This reaction was negligible in CYP2D6-deficient liver microsomes, was inhibited stereoselectively by the quinidine/quinine enantiomer pair, and was cosegregated with dextromethorphan O-demethylation (r = 0.975). The inhibitory effect of methylenedioxymethamphetamine (MDMA) was enhanced by preincubation with microsomes, suggesting that MDMA may produce a metabolite complex with CYP2D6. These findings suggest that phenylisopropylamines as a class interact with CYP2D6 as substrates and/or inhibitors. Their use may cause metabolic interactions with other drugs that are CYP2D6 substrates, and the potential for polymorphic oxidation via CYP2D6 may be a source of interindividual variation in their abuse liability and toxicity.

Amphetamines↗