PubMed Health⌕ Search

Biomedical subjects

Y Nishibe

Publications and source records attributed to Y Nishibe.

At least 19 recordsLinked to original sources
PubMed2001

Induction of intestinal cytochrome P450 (CYP3A) by rifampicin in beagle dogs.

Both male and female beagle dogs (four dogs/sex) were orally treated with rifampicin (Rif) at the dose of 10 mg/kg/day for 7 days and an additional eight dogs (four dogs/sex) were used as a control. The inducible effect of Rif on intestinal cytochrome P450, especially CYP3A enzyme, was investigated by measuring microsomal testosterone 6beta-hydroxylation (6beta-OHT) activity, immunoblot and ELISA analysis. In male dogs, microsomal 6beta-OHT activity in the duodenum, upper, middle and lower part of the jejunum and the ileum of the control was 229, 204, 194, 129 and 57 pmol/min/mg protein, while the activity of the Rif-treated dogs significantly increased to 456, 486, 430, 192 and 138 pmol/min/mg protein, respectively. The activity of intestinal 6beta-OHT in the control and Rif-treated female dogs showed almost similar levels to those observed in the corresponding male dogs. The activity of intestinal 6beta-OHT in both control and Rif-treated dogs was specifically inhibited by anti-CYP3A12 antiserum. The apparent K(m) value for 6beta-OHT activity in all sections of the small intestine was comparable with that in the liver, and no significant changes were observed in between control and Rif-treated dogs. In both control and Rif-treated dogs, immunoblotting of intestinal microsomes with anti-CYP3A12 antiserum produced a band indistinguishable from that of purified CYP3A12 or of immunoreactive CYP3A12 in liver microsomes. A significant increase in intestinal CYP3A content by Rif treatment was quantitatively verified by the ELISA analysis and the magnitude of its increase correlated well with that of 6beta-OHT activity elevation. Furthermore, the results of immunohistochemistry using the anti-CYP3A12 antiserum indicated that CYP3A protein was specifically distributed in epithelial cells throughout the small intestine and appeared to be predominant at the apical side of villus cells. These results demonstrate that Rif induces not only hepatic CYP3A12 but also intestinal CYP3A in dogs.

Administration, Oral↗
PubMed1998

Characterization of cytochrome P450 (CYP3A12) induction by rifampicin in dog liver.

1. Effects of rifampicin (Rif) on the contents of cytochrome P450 (P450) enzymes (CYP1A1/2, 2B11, 2C21 and 3A12) assessed by enzyme-linked immunosorbent assay and catalytic activities (ethoxyresorufin O-deethylase, and testosterone 6 beta-, 16 alpha- and 16 beta-hydroxylase; 6 beta-, 16 alpha- and 16 beta-OHT) in dog liver microsomes were compared between liver lobes of both the male and female dogs. 2. In the control dogs, the contents of individual P450 enzymes and their activities showed no significant differences between individual liver lobes and between the sexes. 3. Rif treatment (10 mg/kg/day, p.o. for 7 days) induced substantial increases in the content of CYP3A12 and 6 beta- and 16 beta-OHT activities, and slight increases in the content of CYP2B11 and 16 alpha-OHT activity, and their elevated levels were virtually the same between liver lobes. The magnitudes of the elevation of the CYP3A12 level and 6 beta- and 16 beta-OHT activities compared with control levels appeared to be greater in the female dogs. However, the ratios of their magnitudes (CYP3A content/6 beta-OHT activity and CYP3A content/16 beta-OHT activity) showed no differences between the sexes. 4. In both the control and Rif-treated dogs, the activities of 6 beta- and 16 beta-OHT were specifically inhibited by anti-CYP3A12 antiserum, and 16 alpha-OHT activity was specifically inhibited by anti-CYP2B11 and anti-CYP2C21 antiserum. 5. These results indicate that Rif treatment induces the expression of CYP3A12 protein, and correlates well with the elevation of its catalytic activity (6 beta- and 16 beta-OHT), and that the female dog is more responsive to Rif treatment as compared with the male.

Animals↗
PubMed1998

Isolation of Inoue-Melnick virus from cerebrospinal fluid of patients with epidemic neuropathy in Cuba.

BACKGROUND: A mysterious disease spread over Cuba from 1991 to 1993, the cause of which has not been fully established. Major symptoms were the same in patients with the Cuban disease as in patients with subacute myelo-optico-neuropathy (SMON), which had occurred in Japan nearly 30 years ago and from which Inoue-Melnick virus (IMV) type 1 was first isolated. We investigated the presence of IMV in cerebrospinal fluid samples of patients with this epidemic neuropathy in Cuba. METHODS: The established method for detecting IMV in MRC-5 fibroblasts was used throughout the study, which was conducted in two independent laboratories, one in Buffalo, NY, and the other in Kyoto, Japan. The cerebrospinal fluid samples of 20 patients and four controls were provided by Cuban researchers. RESULTS: All cerebrospinal fluid specimens from 20 Cuban patients tested were positive for IMV type 2 (100%), and four cerebrospinal fluid specimens from Cuban controls were negative for IMV (0%). These clear-cut results were identical in both laboratories. CONCLUSION: Our study indicates an important association of IMV type 2 with patients of this Cuban epidemic. The etiologic role of IMV type 2 in the epidemic neuropathy in Cuba, along with weak cytopathic effect viruses isolated by the Cuban group, remains to be elucidated.

Animals↗
PubMed1997

Enhancement of in vivo anti-influenza virus activity of 5,7,4'-trihydroxy-8-methoxyflavone by drug delivery system using hydroxypropyl cellulose.

Enhancement of in vivo antiviral activity of 5,7,4'-trihydroxy-8-methoxyflavone (F36) against H3N2 subtype of influenza A virus by drug delivery system (DDS) with hydroxypropyl cellulose (HPC) was studied. Although in the absence of HPC F36 (0.5 mg/kg) showed no antiviral activity against mouse-adapted influenza virus A/Guizhou/54/89 (H3N2) in mice, when F36 solution containing HPC was administered intranasally 5 min after the virus inoculation, proliferation of the virus in both nasal and broncho-alveolar cavities was inhibited significantly. The relationship between concentration (0.2-0.5%) and deposition ratio of HPC was studied. When 10 microliters of fluorescein isothiocyanate (FITC)-conjugated HPC solution was administered intranasally to BALB/c mice, deposition ratio of HPC at 6 h after inoculation in nasal cavity was dependent on its concentration. The deposition ratio of HPC in broncho-alveolar cavity, however, was reversely dependent on its concentration. Anti-influenza virus activity of F36 in nasal and broncho-alveolar cavities was dependent both on the concentration and deposition ratio of HPC. HPC was most effective at 0.5% in nasal cavity and at 0.3% in broncho-alveolar cavity. These results indicate that DDS with HPC enhances the anti-influenza virus activity of F36 in vivo.

Administration, Intranasal↗
PubMed1996

Cloning and sequencing of a gene encoding 16S ribosomal RNA from a novel hyperthermophilic archaebacterium NC12.

A hyperthermophile NC12 was newly isolated from Noboribetsu hot spring. To characterize this organism, a gene coding for 16S rRNA was cloned and sequenced. The 16S rRNA sequence from NC12 shows the highest similarity with those from Pyrodictium occultum and Desulfurococcus mobilis among the sequences in the database, indicating that NC12 belongs to a cluster of extreme thermophiles (Crenarchaeota) in the archaeal domain. However, since the highest identity score was only 91.2%, it is suggested that NC12 may constitute a new genus.

Archaea↗
PubMed1996

Quantitation of cytochrome P450 enzymes (CYP1A1/2, 2B11, 2C21 and 3A12) in dog liver microsomes by enzyme-linked immunosorbent assay.

1. An enzyme-linked immunosorbent assay (ELISA) using specific antisera has been developed to quantify individual cytochrome P450 (P450) enzymes (1A1/2, 2B11, 2C21 and 3A12) in dog liver microsomes. 2. The specific contents of CYP1A1/2, 2B11, 2C21 and 3A12 in untreated male dog liver microsomes determined by the ELISA were 17, 48, 160 and 69 pmol/mg protein respectively, corresponding to 4, 10, 34 and 15% of total optically determined P450 respectively. These P450 enzymes in untreated female dog liver microsomes showed almost similar amounts and relative proportions to those observed in male dog liver microsomes. 3. The oral treatment of male dogs with phenobarbital (PB), rifampicin (Rif) or beta-naphthoflavone (beta-NF) induced significant increases in the contents of CYP1A1/2 (12-fold by beta-NF), 2B11 (16-fold by PB), 2C21 (2-fold by PB) and 3A12 (5-fold by PB and Rif), resulting in marked proportional alterations of the P450 enzymes in dog liver microsomes. 4. This ELISA method will be a useful tool for investigating possible influences (induct on/suppression) of xenobiotics on the expression of P450 enzymes in dog liver.

Animals↗
PubMed1995

Effects on properties of a thiol protease from Xenopus embryos of changes in substrate and assay conditions.

A protease was purified from Xenopus embryos. Proteolytic activity of the protease against BSA had an optimum pH of 3.8 in acetate buffer and was not detectable at neutral pH. However, when embryonic proteins were used as substrates and digested in phosphate buffer, proteolysis of embryonic proteins was enhanced and was detectable from pH 5.0 to pH 7.0. Digestion of three proteins were mainly detected in digestion of total embryonic proteins. The proteins digested had the same mobilities (on SDS polyacrylamide gel) as yolk proteins. The protease was present in the cytoplasm and around yolk granules. We propose that this protease mainly cleaves a certain yolk proteins in the cytoplasm of Xenopus embryos.

Albumins↗
PubMed1995

Induction of cytochrome P-450 isoenzymes in cultured monkey hepatocytes.

The effect of phenobarbital (PB), beta-naphthoflavone (beta-NF) and rifampicin (Rif) on the drug-metabolizing activity of cultured squirrel monkey hepatocytes was examined. The drug metabolizing activity (e.g. alkoxycoumarin dealkylase or steroid hydroxylase) gradually decreased during the culture period with 40-70% activity remaining at 72 hr. When 0.5 mM PB was added to the culture, the activities of 7-methoxycoumarin O-demethylase (MCOD) and 7-ethoxycoumarin O-deethylase (ECOD) increased to 6-7 fold higher level than those of control at 72 hr. Testosterone 6 beta-hydroxylase (6 beta-OH-T) and testosterone 16 beta-hydroxylase (16 beta-OH-T) activities were approx. 3-fold higher than those of the control. Addition of beta-NF significantly increased the activities of 7-ethoxyresorufin O-deethylase (EROD) and ECOD. Though statistically insignificant, Rif slightly increased 6 beta-OH-T activity. Western blot analysis indicated PB induced production of the CYP 2B and 3A subfamilies, while beta-NF and Rif induced that of the CYP 1A and the CYP 3A subfamily, respectively.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1995

Induction of cytochrome P450 3A (CYP 3A) by E 5110, a non-steroidal anti-inflammatory agent (NSAID), and typical CYP 3A inducers in primary cultures of dog hepatocytes.

First, the effect of E 5110, a non-steroidal anti-inflammatory agent (NSAID), on cytochrome P450 subfamilies in dog hepatocyte culture was examined. E 5110 has been shown to cause a drug interaction in dogs and humans via induction of cytochrome P450 3A (CYP 3A). When dog hepatocytes were cultured for 72 h in the presence of 2-30 microM E 5110, the activity levels of ethoxycoumarin O-deethylase (ECOD) and testosterone 6 beta-hydroxylase (6 beta-OH-T) rose dose-dependently. Subsequent Western blot analysis of microsomes from hepatocyte cultures indicated the presence of higher amounts of CYP 2B and 3A proteins than those of the control. Next, the P450 inducing potency of E 5110 was compared with those of phenobarbital, rifampicin, phenytoin and carbamazepine, which induce CYP 3A in human subjects and human hepatocyte cultures. E 5110 was found to be nearly as effective as phenytoin, but less potent than rifampicin, on the basis of 6 beta-OH-T induction.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1993

Reappraisal of modified neutralization test for Inoue-Melnick virus.

Ito et al. (1992) reported an improved modification of the neutralization (NT) test for Inoue-Melnick Virus (IMV) by prolonged 90 min incubation of the mixture of the virus and serum. For confirmation, we compared the results of the NT test by 90 and 60 min incubation. Against human sera, the NT test by 90 min incubation was significantly more sensitive than the test by 60 min incubation. By 90 min incubation, the NT titers increased by 3 to 6 times and approximately 6% of antibody-negative adult sera previously determined in the tests by 60 min incubation turned to positive (more than 1:10). However, antibody-negative sera of Japanese children examined previously in the tests by 60 min incubation remained negative after the 90 min tests. On the other hand, against rabbit immune sera, no significant difference of NT titers was observed between the two NT tests for 90 and 60 min incubation. Also we reinvestigated Japanese adult sera for type 2 IMV infection by the NT test for 90 min incubation, but did not find any serum of type 2 or intermediate type infection. Therefore, it is not necessary to change the previous conclusion that in Japan IMV infections are mostly of type 1.

Animals↗
PubMed1993

Effect of phenobarbital and other model inducers on cytochrome P450 isoenzymes in primary culture of dog hepatocytes.

1. The effects of phenobarbital (PB), beta-naphthoflavone (beta-NF), omeprazole (Omep) and rifampicin (Rif) on drug-metabolizing activities in dog hepatocytes, cultured with William's medium E, were examined. 2. The drug metabolizing activities of the hepatocytes decreased during culture; 7-ethoxycoumarin O-deethylase (ECOD) activity was nearly 70% of initial value at 72 h, but 7-methoxycoumarin O-demethylase (MCOD), 7-propoxycoumarin O-depropylase (PCOD), progesterone 6 beta-hydroxylase (6 beta-OH-P), progesterone 16 alpha-hydroxylase (16 alpha-OH-P), progesterone 21-hydroxylase (21-OH-P), 7-ethoxyresorufin O-deethylase (EROD) activities and total cytochrome P450 content were approx. 50%. 3. When the hepatocytes were cultured with PB, the enzyme activities increased time- and dose-dependently. MCOD, ECOD and PCOD activities increased 5-8 fold with 2 mM PB in 96 h. Similar results were obtained for 6 beta-OH-P, 16 alpha-OH-P and 21-OH-P activities, and total cytochrome P450. The effect of PB was abolished when 2.5 microM cycloheximide or 0.1 microM actinomycin D was included in the culture. 4. Treatment of hepatocytes with 40 microM beta-NF for 72 h resulted in 25-fold elevation of EROD activity. beta-NF enhanced PCOD activity approx. six-fold, while ECOD increased only slightly, and 7-MCOD negligibly. 5. Omep (100 microM) increased EROD activity nearly 10-fold, and 25 microM Rif increased 6 beta-OH-P activity approx. 8-fold, but ECOD only slightly. 6. Western blot analysis of microsomes from cultured dog hepatocytes with anti-rat CYP 2B1 antibodies indicated that PB increased an immunochemically-reactive protein. The protein showed the same mobility as the major dog P450 isozyme (cytochrome P450 PBD-2 or CYP 2B11) purified from liver microsomes of PB-treated male beagle dog. In a similar manner, induction of cytochrome P450 PBD-1 (CYP 3A12) by PB was confirmed.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1992

Catabolism of hemoglobin-haptoglobin complex in microsome subfractions.

After internalization of hemoglobin-haptoglobin complex (Hb-Hp) via receptor-mediated endocytosis (RME) into liver parenchymal cells, organelles containing the complex distribute in the microsome fraction (Ms). Prior to the catabolism, Hb-Hp dissociates symmetrically into two 82,000-dalton (82 kDa) subunits. In the present investigation, the first event of Hb-Hp metabolism in Ms were further examined after [3H-heme, 14C-glogin]Hb-Ho or [125I-Hb]Hp injection to rats. Shortly after the internalization of Hb-Hp, this complex in Ms was intact. At 60 min after injection, radioactive materials of Ms extracted by freezing and thawing (F&T) with yield of 15% were composed of Hb-Hp, 82 kilodaltons (kDa) subunits and Hb metabolites with a ratio of 1:6:13. The heme metabolites were identified as [3H]bilirubin by high performance liquid chromatography (HPLC). The ratio of Hb-Hp/82 kDa subunits/Hb metabolites in microsome residue of the F&T was 40:8:1. The radioactivity in Ms at 60 min localized microsomes subfraction except Golgi light fraction. In electron microscope radioautography of microsome subfraction using [125I]Hb-Hp, silver grains were observed over or within morphologically heterogenous vesicles, e.g. vesicles containing very low density lipoprotein (VLDL) particles with appendage like multi-vesicular body (MVB) or compartment of uncoupling of receptor and ligand (CURL) in Goligi light and intermediate fractions. These studies suggest that Hb-Hp internalized by RME is dissociated symmetrically into two 82 kDa subunits in organelles of Ms, and that organelles with MVB or CURL-like structures are associated with Hb-Hp metabolism.

Animals↗
PubMed1991

Direct isolation of Inoue-Melnick virus from human colorectal carcinoma tissues but not from stomach carcinoma tissues.

Inoue-Melnick virus (IMV) was isolated directly from all of the seven human colorectal adenocarcinoma tissues studied, whereas IMV was not isolated from five human stomach carcinoma tissues. Seven isolates from the Japanese colorectal carcinoma tissues were identified as type 1 IMV by the neutralization test and were sensitive to phosphonoacetic acid, a growth inhibitor of IMV. Furthermore, type 1 IMV-antibody was detected in six of seven sera of the patients whose colorectal carcinoma tissues were positive for virus isolation. In contrast, IMV-antibody was not detected in the five sera of the patients whose stomach carcinoma tissues were tested and found negative for IMV.

Adenocarcinoma↗
PubMed1990

5-Bromodeoxyuridine enhancement of Inoue-Melnick virus synthesis in human colon carcinoma cell lines.

Inoue-Melnick virus (IMV) synthesis in naturally infected human colon carcinoma cell lines can be enhanced by 5-bromodeoxyuridine (BUDR). The optimal conditions for BUDR enhancement differed between two cell lines, SW-480 and DLD-1. SW-480 cells produced 100 times more infectious IMV than DLD-1 cells by BUDR treatment. A clonal difference in IMV synthesis in SW-480 cells was also observed. The highest titer of virus was found in the culture fluid of clone H (SW-480/H) cells treated with BUDR, and a herpes-like virus was detected by negative-staining electron microscopy of concentrates of the culture fluid. One nonproducer clone (SW-480/B) was also activated to produce virus when treated with BUDR.

Adenocarcinoma↗
PubMed1990

Detection of Inoue-Melnick virus (IMV)-antibody in Japanese patients with colorectal carcinoma and isolation of IMV from Japanese colorectal carcinoma cell lines.

The antibody prevalence rate of 3 types of IMV in 24 sera of Japanese patients with colorectal adenocarcinoma (mean age 60.8 years) was 83.3% (20/24). Of 20 positive sera, 19 contained type 1 antibody and one contained type 2. In contrast, the seropositivity of IMV in 21 sera of matched control patients (mean age 60.9 years) with non-colorectal carcinoma such as mammary and lung carcinoma was 23.8% (5/21). The 5 positive sera contained type 1 antibody. The seropositivity to IMV in 79 sera of healthy Japanese over 50 years of age (mean age 62.3 years) was 24.0% (19/79). Again all of the 19 positive-sera contained type 1 antibody. The seropositivity of IMV in the patients with colorectal adenocarcinoma was significantly higher than in the controls, non-colorectal carcinoma patients and healthy persons over 50 years of age (P less than 0.001). Type 1 IMV was isolated from each of 2 recently established Japanese colorectal adenocarcinoma cell lines.

Adenocarcinoma↗
PubMed1989

Enhancement of Inoue-Melnick virus synthesis by 5-bromodeoxyuridine in human meningioma (MG-1) cells.

The authors found remarkable enhancement of Inoue-Melnick virus (IMV) synthesis by 5-bromodeoxyuridine (BUDR) in human meningioma (MG-1) cells, a virus-producer line of type 1 IMV. Treatment with BUDR resulted in rapid and abundant synthesis of infectious IMV in MG-1 cells. The titer of the cell-associated virus in treated cells increased approximately 6.0 log 10 compared with that in untreated cells. Immunofluorescent antibody tests revealed that IMV-associated late antigen was induced by BUDR in the cytoplasm of approximately 50% of treated cells. A clonal difference was also found in the enhancement of BUDR on the IMV synthesis in MG-1 cells. The most remarkable enhancing effect of BUDR was observed in the clone C line, and a herpes-type virus was detected by negative-staining electron microscopy in the culture fluid of the clone C treated with BUDR.

Antigens, Viral↗