Biomedical subjects

M Kitada

Publications and source records attributed to M Kitada.

At least 163 records · Page 9Linked to original sources

PubMed1989

Decrease in a constitutive form of cytochrome P-450 by macrolide antibiotics.

The effects of administration of macrolide antibiotics on cytochrome P-450 in liver microsomes of male rats were investigated. The macrolides tested were those with a 14-membered ring such as oleandomycin, troleandomycin, erythromycin and erythromycin estolate, and those with a 16-membered ring such as rokitamycin, leucomycin and josamycin. Cytochrome P-450-metabolite complex was detected with oleandomycin, troleandomycin, erythromycin and erythromycin estolate, whereas no such effect was observed with rokitamycin, leucomycin and josamycin. The content of uncomplexed cytochrome P-450 in liver microsomes remained unchanged with rokitamycin, leucomycin and josamycin, decreased with troleandomycin and oleandomycin, and increased with erythromycin and erythromycin estolate, indicating that oleandomycin, troleandomycin, erythromycin and erythromycin estolate also affect the amounts of other forms of cytochrome P-450. The administration of oleandomycin, troleandomycin, erythromycin and erythromycin estolate resulted in a dramatic decrease in the activities of testosterone 2 alpha- and 16 alpha-hydroxylases in liver microsomes. Supporting these results, a marked decrease (more than 75%) in the content of P-450-male, a major constitutive form of cytochrome P-450 in male rats, was noted with oleandomycin, troleandomycin, erythromycin and erythromycin estolate, while the decrease was rather small with rokitamycin and leucomycin. We conclude that the administration of the 14-membered ring macrolides may affect drug and steroid metabolism not only by formation of P-450-metabolite complex but also by decrease in the content of P-450-male.

Animals↗

PubMed1989

Molecular cloning and sequence analysis of cDNA containing the entire coding region for human fetal liver cytochrome P-450.

From a human fetal liver cDNA library, a cDNA clone (lambda HFL33) containing the entire coding region for a form of cytochrome P-450 related to P-450 HFLa was obtained. The clone was 1,971 bp long and had an open reading frame of 1,509 nucleotides coding for a 503 amino acid polypeptide. The nucleotide and the deduced amino acid sequences of lambda HFL33 were very similar to but clearly distinct from those of NF25 and HLp cDNAs, which code for forms of cytochrome P-450 in adult human liver. The deduced N-terminal amino acid sequence of the HFL33 protein was identical to that of P-450 HFLa.

Amino Acid Sequence↗

PubMed1989

The sodium/proton antiport system in a newly isolated alkalophilic Bacillus sp.

The pH homeostasis and the sodium/proton antiport system have been studied in the newly isolated alkalophilic Bacillus sp. strain N-6, which could grow on media in a pH range from 7 to 10, and in its nonalkalophilic mutant. After a quick shift in external pH from 8 to 10 by the addition of Na2CO3, the delta pH (inside acid) in the cells of strain N-6 was immediately established, and the pH homeostatic state was maintained for more than 20 min in an alkaline environment. However, under the same conditions, the pH homeostasis was not observed in the cells of nonalkalophilic mutant, and the cytoplasmic pH immediately rose to pH 10. On the other hand, the results of the rapid acidification from pH 9 to 7 showed that the internal pH was maintained as more basic than the external pH in a neutral medium in both strains. The Na+/H+ antiport system has been characterized by either the effect of Na+ on delta pH formation or 22Na+ efflux in Na+-loaded right-side-out membrane vesicles of strain N-6. Na+- or Li+-loaded vesicles exhibited a reversed delta pH (inside acid) after the addition of electron donors (ascorbate plus tetramethyl-p-phenylenediamine) at both pH 7 and 9, whereas choline-loaded vesicles generated delta pHs of the conventional orientation (inside alkaline). 22Na+ was actively extruded from 22Na+-loaded vesicles whose potential was negative at pH 7 and 9. The inclusion of carbonyl cyanide m-chlorophenylhydrazone inhibited 22Na+ efflux in the presence of electron donors. These results indicate that the Na+/H+ antiport system in this strain operates electrogenically over a range of external pHs from 7 to 10 and plays a role in pH homeostasis at the alkaline pH range. The pH homeostasis at neutral ph was studied in more detail. K+ -depleted cells showed no delta pH (acid out) in the neutral conditions in the absence of K+, whereas these cells generated a delta pH if K+ was present in the medium. This increase of internal pH was accompanied by K+ uptake from the medium. These results suggest that electrogenic K+ entry allows extrusion of H+ from cells by the primary proton pump at neutral pH.

Bacillus↗

PubMed1989

Immunochemical studies for the presence of P-450 HFLa, a form of cytochrome P-450 in human fetal livers in human hepatocellular carcinoma cells.

Immunohistochemical localization of P-450 HFLa, a form of cytochrome P-450 in human fetal livers was investigated in human hepatocellular carcinoma. The cytoplasm of carcinoma cells positively reacted with anti-P-450 HFLa antibodies. It was found that the carcinoma cells showing a pseudoglandular pattern or poorly differentiated appearance exhibited a weaker reactivity with anti-P-450 HFLa antibodies than did relatively differentiated carcinoma cells. In the case of hepatoblastoma, the polygonal or round-shaped tumor cells which differentiated into epithelial structure exhibited a positive reaction with anti-P-450 HFLa antibodies, whereas the spindle-shaped tumor cells which showed a sarcomatous appearance did not react with the antibodies.

Adult↗

PubMed1989

Induction of cytochrome P-450 isozymes by chromanamine derivatives in rat liver.

1. Pretreatment of rats with 6-(3-picolyl)amino-2,2,5,8-tetramethylchromane (PATC) for 7 days resulted in a significant increase in the activities of benzphetamine N-demethylase, p-nitroanisole O-demethylase and aniline hydroxylase in liver microsomes prepared 24 h after the last treatment. 2. Analysis by Western blot showed that PATC induces cytochrome P-450 b, P-450 c and P-450 d, which are the major forms of cytochrome P-450 in liver microsomes of rats when pretreated with phenobarbital and 3-methylcholanthrene. 3. Exposure of liver sections to the antibodies to cytochrome P-450 b and P-450 c resulted in intense immunostaining within the centrilobular regions, but produced staining of considerably weaker intensity in the perilobular region. Semiquantitative immunochemical analysis, by image analyser, of cytochrome P-450 b and P-450 c showed that centrilobular hepatocytes were stained more intensively than perilobular hepatocytes. 4. These results indicate that PATC induces cytochromes P-450 b and P-450 c, in the centrilobular hepatocytes to a greater degree than those in the perilobular hepatocytes. 5. Co-administration of PATC with pentobarbital caused a significant increase in pentobarbital sleeping time. Furthermore, PATC was found to cause a decrease in the activity of benzphetamine N-demethylase in liver microsomes prepared 30 min after treatment with the drug.

Animals↗

PubMed1989

[Resistance to anticancer drugs in relation to cytochrome P-450].

Cytochrome p-450 is a product of a multigene family, and catalyzes the activation and the detoxication of a wide variety of exogenous as well as endogenous compounds. Recent studies have the purified forms of cytochrome p-450 and provided evidence that some anticancer agents are metabolically activated by the cytochrome. In general, cancer cells express lower amounts of cytochrome p-450 as compared to normal liver cells. We recently succeeded in purifying P-450 HFLa, a form of cytochrome P-450 in human fetal livers. Examinations using antibodies to P-450 HFLa, however, showed that proteins cross-reactive with antibodies to P-450 HFLa existed in gynecologic malignancies. Development of multiple drug resistance is usually associated with a decrease in the content of cytochrome P-450, which is in contrast with glutathione S-transferase and a few other enzymes. The mechanisms responsible for such altered enzyme activity by multiple drug resistance are unclear as yet.

Animals↗

PubMed1989

Form-specific degradation of cytochrome P-450 by lipid peroxidation in rat liver microsomes.

Microsomal lipid peroxidation caused decreases in the activities of ethylmorphine N-demethylase and testosterone 6 beta-hydroxylase more markedly than aniline hydroxylase, p-phenetidine O-deethylase and testosterone 2 alpha- and 16 alpha-hydroxylases. Results of sodium dodecylsulfate-polyacrylamide gel electrophoresis of liver microsomes showed that proteins with molecular weights between 47kDa and 50kDa in liver microsomes were sensitively degraded by lipid peroxidation. Western-blot analysis of liver microsomes with antibodies to P-448-H, P-450 male and P-450 PB-1 which corresponded to P-450d, P-450h and P-450 PCN, respectively, showed that the amount of P-450 PB-1 was decreased more markedly by lipid peroxidation as compared to those of P-450 male and P-448-H. It seemed, therefore, likely that the stability of cytochrome P-450 to lipid peroxidation varies dependent on the forms of cytochrome P-450.

Animals↗

PubMed1989

[Long-term survival in patients with breast cancer after intra-arterial infusion chemotherapy].

Twenty two patients with locally advanced breast cancer survived for more than 5 years after intra-arterial infusion chemotherapy (IA). In this study, we compared these long-term-survivors with thirteen cases who died within 2 years. The results were as follows. (1) ER positive rate of the long-term-survivors (90%) was significantly higher than in short-term-survivors (25.0%). (2) There was no difference between the response rates of each group; 63.2% in long-term-survivors vs. 53.8% in short-term-survivors. (3) Adjuvant endocrine therapies were carried out in the former group, and their D.F.I. were considerably longer than in the latter group. (4) Common sites of recurrence in long-term-survivors were soft tissues and bones, compared with visceral in short-term-survivors. Post-recurrence survivals of the former were, also, longer than in the latter. From these results, we confirmed that preoperative IA and following adjuvant endocrine therapies induces favorable results in the treatment of hormone sensitive breast cancer.

Breast Neoplasms↗

PubMed1988

Sex-related difference in oxidative metabolism of testosterone and erythromycin by hamster liver microsomes.

The activities of testosterone hydroxylases and erythromycin N-demethylase were significantly higher in liver microsomes from female hamsters than in the male counterparts. SDS-polyacrylamide gel electrophoresis revealed a difference in protein composition between male and female liver microsomes in the molecular mass region comprising cytochrome P-450. Western blot analysis showed further that antibodies to rat male-specific cytochrome P-450 crossreacted with at least two proteins in both male and female hamster microsomes, but one of the female proteins had a different molecular mass from that of the male proteins. It is concluded that sex difference in liver microsomal cytochrome P-450 is not restricted to rats and mice, as has previously been believed.

Animals↗

PubMed1988

Immunochemical similarity of P-450 HFLa, a form of cytochrome P-450 in human fetal livers, to a form of rat liver cytochrome P-450 inducible by macrolide antibiotics.

A protein immunochemically related to P-450 HFLa, a form of cytochrome P-450 purified from human fetal livers, was detected in rat liver microsomes. The content of the immunoreactive protein in rat liver microsomes was increased by treatments with phenobarbital, pregnenolone 16 alpha-carbonitrile (PCN), erythromycin, erythromycin estolate, and oleandomycin but not with 3-methylcholanthrene, imidazole, ethanol, isosafrole, josamycin, midecamycin, or miocamycin. The activity of erythromycin N-demethylase correlated with the content of the immunoreactive protein in rat liver microsomes (r = 0.72). In addition, anti-P-450 HFLa IgG inhibited erythromycin N-demethylase in liver microsomes from erythromycin- or oleandomycin-pretreated rats. Furthermore, the content of the immunoreactive protein highly correlated with that of P-450 PB-1, which is distinct from Waxman's terminology, and is one of the forms of PCN-inducible cytochrome P-450s (r = 0.95). From these results and the results reported so far, it seems possible that P-450 HFLa is one of the forms of cytochrome P-450 inducible by glucocorticoids.

Animals↗

PubMed1988

Cytochrome P-450 in human liver microsomes: high-performance liquid chromatographic isolation of three forms and their characterization.

Three forms of cytochrome P-450, designated as P-450-HM1, P-450-HM2, and P-450-HM3, were isolated from human liver microsomes using high-performance liquid chromatography (HPLC) techniques. Each purified preparation showed a single protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). From the results of SDS-PAGE, the molecular weights of P-450-HM1, P-450-HM2, and P-450-HM3 were estimated to be 51,000, 54,000, and 52,000, respectively. The oxidized absolute spectra of these three forms of cytochrome P-450 showed Soret absorption peaks at around 417 nm, indicating that these forms were in the low spin state. In a reconstituted system, P-450-HM1 showed the highest catalytic activities of nifedipine and (S)- or (R)-nilvadipine oxidases. The same form showed higher activities of testosterone 6 beta-hydroxylase and progesterone 6 beta- and 16 alpha-hydroxylases. P-450-HM2 showed high N-demethylase activities for benz-phetamine and aminopyrine, and also showed the highest activity of testosterone 16 beta-hydroxylase among the three forms, while it did not show detectable activities of testosterone 6 beta-hydroxylase and progesterone 6 beta- and 16 alpha-hydroxylases. Anti-P-450-HM1 immunoglobulin G (IgG), but not anti-P-450-HM2 IgG, inhibited the activities of testosterone 6 beta-hydroxylase and nifedipine and nilvadipine oxidases in human liver microsomes. Anti-P-450-HM1 IgG was also inhibitory against progesterone 6 beta- and 16 alpha-hydroxylases.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1988

Purification and some properties of NADPH-cytochrome P-450 reductase from crab-eating monkey liver microsomes.

NADPH-cytochrome P-450 reductase was purified to 30.8 units/mg from monkey liver microsomes. The purified reductase showed one major protein band (78,000) and two minor ones (58,000 and 20,000) on analysis by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Monkey, rat, and guinea pig reductases were not immunochemically identical to each other judged from Ouchterlony double diffusion analysis and immunotitration with regard to NADPH-cytochrome c reductase activity.

Amino Acids↗

PubMed1988

The proteins immunochemically related to P-450 HFLa, a major form of cytochrome P-450 in human fetal livers, are present in liver microsomes from various animal species.

Proteins immunochemically reactive with anti-P-450 HFLa IgG were detectable in liver microsomes from all of the animals examined, although considerable variations of the amounts were observed among the animal species. The smallest amount was found in liver microsomes from female rats and the largest amount in monkey liver microsomes. Sex difference in the amounts was observed in rat liver microsomes but not in dog liver microsomes. No strain difference was observed among ddY, ICR and BALB/C mice. The activities of testosterone 6 beta-hydroxylases in liver microsomes from rats, dogs and monkeys were highly sensitive to inhibition by anti-P-450 HFLa IgG, but those in microsomes from guinea pigs and rabbits were less sensitive to inhibition by the antibodies.

Animals↗

PubMed1988

Polyamine lowered the hepatic lipid peroxide level in rats.

This is the first report for the hepatic lipid peroxide lowering effect of spermine in vivo. The influence of administration of polyamines on hepatic lipid peroxide level has been investigated by using normal or carbon tetrachloride (CCl4)-treated rats. Spermine was found to lower the hepatic lipid peroxide level most efficiently among polyamines used in CCl4-treated rats. In addition, the extent of liver enlargement caused by CCl4 treatment was reduced by spermine administration. Lipid peroxide lowering effect of spermine was also observed in normal rats. Hepatic spermine content was significantly increased in both normal and CCl4-treated rats after administration of spermine. Clear inverse relationship between the content of lipid peroxide and the concentration of spermine was observed. In reconstituted system containing NADPH-cytochrome P-450 reductase and extracted hepatic microsomal lipid, spermine inhibited the NADPH-dependent lipid peroxidation effectively at the concentration of 0.1 mM. From these results, we concluded that spermine exerted an inhibitory effect of lipid peroxidation in vivo as well as in vitro.

Animals↗

PubMed1988

Effects of muroctasin on the activities of drug metabolizing enzymes in liver microsomes of rats.

1. Effects of repeated administration of N2-[(N-acetylmuramoyl)-L-alanyl-D-isoglutaminyl]-N6-stearoyl-L-lysine (MDP-Lys (L18), muroctasin) to female rats on the activities of drug metabolizing enzymes in liver microsomes were examined. The in vitro effects of the compound on the activities of drug metabolizing enzymes in liver microsomes from male rats were also investigated. 2. The subcutaneous administration of MDP-Lys (L18) at a dose of 1 mg/kg (high dose) caused slight but significant decrease in the contents of cytochrome P-450 and cytochrome b5. The daily subcutaneous injection at a dose of 0.1 mg/kg (middle dose) resulted in the induction of aminopyrine N-demethylase, aniline hydroxylase and 7-ethoxycoumarin O-deethylase. Such induction of the enzymes was seen only when calculated on the basis of microsomal protein but not wet weight of livers. The changes were relatively small as compared with those caused by phenobarbital. 3. At one week after the last injection of the high dose of MDP-Lys (L18), slightly higher levels of the contents of cytochrome P-450 and cytochrome b5 and the activity of NADPH-cytochrome c reductase were noted. The cessation of the administration tended to increase the activities of drug metabolizing enzymes in rats treated with the high dose of the drug. These changes were seen only when the activities were calculated on the basis of mg of microsomal protein. 4. MDP-Lys (L18) inhibited drug metabolizing enzymes in vitro to various extents depending on the substrate used.(ABSTRACT TRUNCATED AT 250 WORDS)

7-Alkoxycoumarin O-Dealkylase↗

PubMed1987

P-450 HFLa, a form of cytochrome P-450 purified from human fetal livers, is the 16 alpha-hydroxylase of dehydroepiandrosterone 3-sulfate.

In a reconstituted system containing NADPH, dilauroyl-L-3-phosphatidylcholine, and NADPH-cytochrome P-450 reductase purified from rat liver microsomes, cytochrome P-450 (P-450 HFLa) purified from human fetal livers catalyzed the 16 alpha-hydroxylation of dehydroepiandrosterone 3-sulfate (DHEA-sulfate). Addition of cytochrome b5 purified from rat liver microsomes to the reconstituted system resulted in a remarkable increase in the hydroxylase activity. The level of P-450 HFLa in liver homogenates from human fetuses highly correlated with the activity of DHEA-sulfate 16 alpha-hydroxylase. Antibodies to P-450 HFLa inhibited the 16 alpha-hydroxylation of DHEA-sulfate in a dose-dependent manner. The NH2-terminal amino acid sequence of P-450 HFLa was similar to that of P-450NF (Beaune, P. H., Umbenhauer, D. R., Bork, R. W., Lloyd, R. S., and Guengerich, F. P. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 8064-8068). We conclude that P-450 HFLa is a form of cytochrome P-450 involved in the 16 alpha-hydroxylation of DHEA-sulfate.

Amino Acid Sequence↗

PubMed1987

Sex difference in responsiveness to Aztreonam of monooxygenase system in liver microsomes from rats.

Effect of successive administration of Aztreonam on microsomal monooxygenase system was investigated in male and female Sprague-Dawley rats. The activities of benzphetamine N-demethylase, aminopyrine N-demethylase, p-nitroanisole O-demethylase and aniline hydroxylase in liver microsomes from male rats were decreased dose-dependently by Aztreonam. On the contrary, the activities in liver microsomes from female rats were slightly increased rather than decreased by the administration of Aztreonam. In addition, Aztreonam was found to decrease the specific content of microsomal cytochrome P-450 in male rats but not in female rats. The decreases in the activities observed in male rats were accompanied by a parallel decrease in the specific content of cytochrome P-450. Furthermore, the results of quantitation of P-450 (M-1), one of the male specific forms of cytochrome P-450, indicated that the administration of Aztreonam resulted in a dose-dependent decrease in the content of P-450 (M-1) in liver microsomes from male rats.

Aminopyrine N-Demethylase↗

PubMed1987

Significance of cytochrome P-450 (P-450 HFLa) of human fetal livers in the steroid and drug oxidations.

The purpose of this study was to clarify the pharmacological and physiological significance of P-450 HFLa. Thus, correlations between cytochrome P-450 (P-450 HFLa) level and different monooxygenase activities were investigated in liver homogenates from human fetuses. Poor correlation was seen between P-450 HFLa level and the activity of benzphetamine N-demethylation or aniline hydroxylation. In contrast, the content of P-450 HFLa was highly correlated with the activity of benzo(a)pyrene hydroxylation, 7-ethoxycoumarin O-deethylation or testosterone 6 beta-hydroxylation. In microsomes from human adult livers, a moderate relationship was also observed between testosterone 6 beta-hydroxylation and P-450 HFLa level. Furthermore, antibodies to P-450 HFLa inhibited testosterone 6 beta-hydroxylase activity in fetal and adult livers to similar extents. We conclude that P-450 HFLa is a form of cytochrome P-450 which catalyzes testosterone 6 beta-hydroxylation and limited drug oxidations in human fetal and adult livers.

7-Alkoxycoumarin O-Dealkylase↗