Biomedical subjects

M Kitada

Publications and source records attributed to M Kitada.

At least 55 records · Page 3Linked to original sources

PubMed1993

[Evaluation of subselective intraarterial infusion chemotherapy in far advanced gastric and colorectal cancer].

We investigated the usefulness of subselective intraarterial infusion chemotherapy in far advanced gastric and colorectal cancer. Among gastric and colorectal cancer cases undergoing surgery at our hospital for the past ten years, patients with and without palliative resection were studied. Forty gastric cancer patients and 29 colorectal cancer patients were treated by subselective intraarterial infusion chemotherapy. In gastric cancer cases without resection, a significantly longer survival was noted in patients undergoing this therapy with over 5 g of 5-FU than those treated with conventional chemotherapy. In gastric cancer patients with palliative resection and colorectal cancer patients, survival time was longer by intraarterial infusion with over 5 g of 5-FU, but not significant. Partial response was obtained in 5 cases of gastric cancer and 3 cases of colorectal cancer, and clinical symptoms were improved in 44% of the patients. The main complications of this therapy were myelosuppression and occlusion of the catheter, but none of them were serious. For the improved quality of life of cancer patients, subselective intraarterial infusion chemotherapy is considered a safe and useful form of treatment.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1992

Molecular cloning of monkey liver cytochrome P-450 cDNAs: similarity of the primary sequences to human cytochromes P-450.

Three cDNAs coding for monkey cytochrome P-450 (P450) 2C, 2E and 3A (MKmp13, MKj1 and MKnf2, respectively) were isolated from a lambda gt11 cDNA library of a liver from a 3-methylcholanthrene (3MC)-treated crab-eating monkey, using cDNA fragments for human P450 2C, 2E and 3A as respective probes. MKmp13 and MKnf2 were 1901 and 2032 bp long, containing entire coding regions for polypeptides of 490 and 503 residues, respectively. The deduced N-terminal amino acid sequences of MKmp13 and MKnf2 were identical with those of P450-MK1 and P450-MK2, which had been purified from liver microsomes of untreated and polychlorinated biphenyl (PCB)-treated crab-eating monkeys, respectively. MKj1 was 1508 bp long, encoding a polypeptide of 449 residues, which is presumed to lack N-terminal 45 residues as compared with the sequence for human P450 2E1. Northern blot analysis indicated that monkey P450 2C, 2E and 3A mRNAs were expressed constitutively in monkey livers. P450 2E and 3A mRNAs were induced by both 3MC and PCB, while P450 2C mRNA was induced only by PCB. The deduced amino acid sequences of four monkey cytochrome P-450 cDNAs, including P450 1A1 (MKah1) which we isolated previously, were more than 92% identical with those of corresponding human cytochrome P-450 cDNAs.

Amino Acid Sequence↗

PubMed1992

Immunochemical characterization and toxicological significance of P-450HFLb purified from human fetal livers.

Immunochemical properties of P-450HFLb purified from human fetal livers were investigated. P-450HFLb cross-reacted with antibodies to rat P-4501A1 but not with antibodies to CYP2A6, CYP2C9, CYP3A7 (P-450HFLa) and rat CYP2B1. In addition, P-450HFLb also cross-reacted with both monospecific antibodies to rat CYP1A1 and CYP1A2. However, P-450HFLb was shown to be an immunochemically distinct form of cytochrome P-450 from P-450PA (human CYP1A2). Immunoblot analysis of human fetal livers with the antibodies to P-450HFLb showed that P-450HFLb was expressed in all fetal livers studied although there appeared to be individual differences in the amounts of P-450HFLb expressed in fetal livers. The formation of mutagens from IQ (but not from AFB1) in fetal liver homogenates was inhibited by the antibodies to P-450HFLb in a dose dependent manner. These results suggest that P-450HFLb may be a form of human cytochrome P-450 classified into CYP1 gene family, and that the cytochrome P-450 is, in part, responsible for the mutagenic activation of IQ in human fetal livers as well as CYP3A7 (P-450HFLa).

Aflatoxin B1↗

PubMed1992

Evaluation of adriamycin-induced lipid peroxidation.

Lipid peroxidation is known to be a mechanism for Adriamycin-induced toxicity. In the present study, two methods which detect fluorescent substances and high molecular weight protein aggregates in peroxidized membranes were applied to Adriamycin-induced lipid peroxidation in liver microsomes. A rat liver microsomal suspension containing an NADPH-generating system was incubated with Adriamycin. Thiobarbituric acid reactive substances (TBA-RS), formed during this incubation, were transferred from the microsomes to the medium. Fluorescent substances determined by the fluorescence emitted from both the microsomes themselves and the chloroform/methanol extracts of the microsomes, were found to be formed during this incubation. High molecular weight protein aggregates determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were also formed. Fluorescent substances and high molecular weight protein aggregates were found in microsomal membranes themselves and increased time dependently. These substances retained in membranes can be of great use to delineate the site of Adriamycin-induced lipid peroxidation in vitro and in vivo and to determine how this lipid peroxidation affects the membrane.

Animals↗

PubMed1992

Molecular cloning of monkey P450 1A1 cDNA and expression in yeast.

Monkey P450 1A1 cDNA (MKah1) was isolated from the lambda gt11 cDNA library of a liver from a 3-methylcholanthrene (3MC)-treated crab-eating monkey using a dog P450 1A1 cDNA fragment as a probe. MKah1 was 2453 bp long and contained an entire coding region for a polypeptide of 512 residues. The nucleotide and deduced amino acid sequences of MKah1 displayed 95% and 94% identity with those of the human P450 1A1 gene, respectively. Even in the 3' noncoding region, MKah1 showed 94% homology with human P450 1A1, whereas it showed less than 69% homology with other mammalian P450 1A1. Monkey P450 1A1 mRNA was not detectable in untreated livers, but was induced by polychlorinated biphenyl and 3MC. The expression plasmid (designated as pMKC-1) was constructed by introduction of the coding region of MKah1 into a yeast expression vector (pAM82) containing the promoter of acid phosphatase (APase). Northern blot analysis revealed that monkey P450 1A1 mRNA was expressed in yeast under the control of the APase promoter. Microsomes from yeast transformed by pMKC-1 catalyzed 7-ethoxycoumarin O-deethylation, benzo(a)pyrene hydroxylation and the mutagenic activation of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 3-amino-1-methyl-5H-pyrido(4,3-b)-indole acetate (Trp-P-2) and 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole acetate (Glu-P-1).

Amino Acid Sequence↗

PubMed1992

A new form of cytochrome P-450 responsible for mutagenic activation of 2-amino-3-methylimidazo[4,5-f]quinoline in human livers.

Antibodies to P-450IA2 strongly inhibited the mutagenic activation of 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate but not aflatoxin B1 in human liver microsomes. The anti-rat P-450IA2 antibodies were capable of recognizing two proteins which show different mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of human liver microsomes. A new form of cytochrome P-450 (designated P-450-HM4) cross-reactive with anti-rat P-450IA2 antibodies showing that the smaller molecular weight was purified from human liver microsomes by means of the fast-performance liquid chromatography system. The molecular weight of P-450-HM4 was estimated to be 49,000, which was apparently different from that of P-450PA (human P-450IA2). The antibodies to P-450-HM4 did not cross-react with P-450PA (human P-450IA2) but inhibited to various extents the mutagenic activation of IQ in microsomes from human livers. In addition, P-450-HM4 showed significant mutagen-producing activity from IQ in a reconstituted system. Together with these and other results reported previously, it is concluded that at least two forms of cytochrome P-450 [P-450-HM4 and P-450PA (human P-450IA2)] are involved in the mutagenic activation of IQ in human liver.

Antibodies↗

PubMed1992

Stable expression of cytochrome P450IIIA7 cDNA in human breast cancer cell line MCF-7 and its application to cytotoxicity testing.

A mammalian cell expression plasmid containing cytochrome P450IIIA7 complementary DNA was constructed. Breast cancer cells (MCF-7) were transfected with the plasmid and neomycin-resistant selection marker plasmid. We established three cell lines, termed M13, M21, and M27, which expressed the cytochrome P450IIIA7 as examined by RNA blot and immunoblot analyses. These cell lines showed 8- to 10-fold higher sensitivity against aflatoxin B1 compared to parental MCF-7 cells, suggesting that cytochromes P450IIIA7 expressed in the cells were responsible for the production of the cytotoxic metabolite of aflatoxin B1.

Adult↗

PubMed1992

Toxicological significance of dog liver cytochrome P-450: examination with the enzyme expressed in Saccharomyces cerevisiae using recombinant expression plasmid.

A complementary DNA (cDNA) coding for a form of beagle dog cytochrome P-450 (Dah1), which is the orthologue to the CYP1A1 cDNA of rat, mouse and human, was inserted between the alcohol dehydrogenase (ADH) promoter and terminator regions of the yeast expression vector pAAH5. On introduction of the resulting recombinant plasmid pDC-1, Saccharomyces cerevisiae strain AH22 cells synthesized up to 1.5 x 10(5) molecules per cell of cytochrome P-450 protein (P-450(Dah1)). The carbon monoxide-bound reduced form of P-450(Dah1) showed an absorption peak at 447 nm and specific content of P-450(Dah1) was about 0.1 nmole P-450 per mg of microsomal protein. P-450(Dah1) cross-reacted with antibodies to rat P-448-H (CYP1A2) and dog P-450-D2 (CYP1A2). P-450(Dah1) activated 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) most efficiently in the umu test and exhibited a high activity of aryl hydrocarbon hydroxylase toward benzo[a]pyrene.

Animals↗

PubMed1992

Kinetic properties of electrogenic Na+/H+ antiport in membrane vesicles from an alkalophilic Bacillus sp.

The effects of imposed proton motive force on the kinetic properties of the alkalophilic Bacillus sp. strain N-6 Na+/H+ antiport system have been studied by looking at the effect of delta psi (membrane potential, interior negative) and/or delta pH (proton gradient, interior alkaline) on Na+ efflux or H+ influx in right-side-out membrane vesicles. Imposed delta psi increased the Na+ efflux rate (V) linearly, and the slope of V versus delta psi was higher at pH 9 than at pH 8. Kinetic experiments indicated that the delta psi caused a pronounced increase in the Vmax for Na+ efflux, whereas the Km values for Na+ were unaffected by the delta psi. As the internal H+ concentration increased, the Na+ efflux reaction was inhibited. This inhibition resulted in an increase in the apparent Km of the Na+ efflux reaction. These results have also been observed in delta pH-driven Na+ efflux experiments. When Na(+)-loaded membrane vesicles were energized by means of a valinomycin-induced inside-negative K+ diffusion potential, the generated acidic-interior pH gradients could be detected by changes in 9-aminoacridine fluorescence. The results of H+ influx experiments showed a good coincidence with those of Na+ efflux. H+ influx was enhanced by an increase of delta psi or internal Na+ concentration and inhibited by high internal H+ concentration. These results are consistent with our previous contentions that the Na+/H+ antiport system of this strain operates electrogenically and plays a central role in pH homeostasis at the alkaline pH range.

Alkalies↗

PubMed1992

A case of hypothyroidism with simultaneous presence of stimulating type anti-thyrotropin (TSH) receptor antibodies and anti-thyroxine (T4) autoantibodies.

We have examined a hypothyroid patient with stimulating type anti-thyrotropin (TSH) receptor antibodies and without blocking type anti-TSH receptor antibodies. Although she had high serum TSH (240 microU/ml) and low free triiodothyronine (FT3, 0.49 pg/ml) concentrations, which agree with physical findings of hypothyroidism, she had an unusually high free thyroxine (FT4) concentration (3.56 ng/dl). Incubation of her serum with 125I-T4, followed by precipitation with 12.5% polyethylene glycol (PEG) disclosed a higher binding of 125I-T4 (34.4%) than in normal controls, being 5-7%. In addition, binding of 125I-T4 to her serum gamma-globulin was completely displaced by the addition of unlabelled T4. From these results it was concluded that her serum contained anti-T4 autoantibodies. Treatment with synthetic T4 was begun and her thyroid function was monitored by sensitive TSH radioimmunoassay (RIA) and RIA of FT4 after PEG treatment. Since both sensitive TSH RIA and FT4 RIA results after PEG treatment give results concordant with the physical findings, it was concluded that both of the RIA results are useful for the evaluation of thyroid function in patients with thyroid hormone autoantibodies.

Aged↗

PubMed1992

Human fetal liver cytochrome P-450: capacity to form genotoxic metabolites.

Unlike most experimental animals, human fetal liver possesses forms of cytochrome P-450. Thus, the purpose of this study was to clarify the toxicological significance of these forms of cytochrome P-450 to understand possible roles of these cytochromes in producing genotoxic metabolites from promutagens. In fact, human fetal livers showed considerable capacity to activate aflatoxin B1 and IQ (2-amino-3-methylimidazo [4,5-f] quinoline). Three of four forms of cytochrome P-450, P-450HFLa-d, which we could purify from human fetal livers were capable of activating promutagens to mutagens. One of these three forms, namely P-450HFLa, catalyzed the metabolic activation of aflatoxin B1 and IQ. An expression plasmid containing HFL33 cDNA encoding P-450HFLa was constructed and the protein expressed in insect (Sf9) cells and in human cancer cells, MCF-7. Aflatoxin B1 was efficiently activated to a mutagen upon addition of the lysate of Sf9 cells to the incubation mixture for the assay. Transformants of MCF-7 cells expressing P-450IIIA7 (HFLa) showed higher sensitivity to aflatoxin B1 than the parental MCF-7 cells as detected by cytotoxicity.

Animals↗

PubMed1992

Examination for lipid peroxidation in liver microsomes of guinea pigs as a causal factor in the decrease in the content of cytochrome P-450 due to ascorbic acid deficiency.

The content of cytochrome P-450 in liver microsomes from guinea pigs was decreased by ascorbic acid-deficiency. Since ascorbic acid is an antioxidant in vivo, the possible involvement of lipid peroxidation in this phenomenon was investigated. In fact, the level of lipid peroxides in liver homogenates of guinea pigs was increased by ascorbic acid deficiency. The level was significantly decreased when the animals were given tocopherol acetate (25 mg/kg/day, s.c.) with an ascorbic acid-free diet. The activities of aminopyrine N-demethylase, aniline hydroxylase, p-nitroanisole O-demethylase and 7-ethoxycoumarin O-deethylase, and the content of cytochrome P-450 spectrally determined did not restore the control level by the administration of tocopherol acetate to the ascorbic acid-deficient animals. Western blot analysis of liver microsomes with antibodies to rat P-450IA2 (P-448-H), P-450IIB1 (P-450b) and human P-450IIIA4 (P-450NF) showed that ascorbic acid-deficiency resulted in a decrease in the amount of cytochrome P-450 immunochemically related to P-450IA2, but not the amounts of the forms of cytochrome P-450 cross-reactive with antibodies to P-450IIB1 and P-450IIIA4. The reduced amounts of cytochrome P-450 cross-reactive with antibodies to rat P-450IA2 in liver microsomes of ascorbic acid-deficient animals remained unchanged even when lipid peroxidation was inhibited by tocopherol acetate, suggesting that there is a mechanism(s) other than lipid peroxidation involved in the reduction of amounts of cytochrome P-450 by ascorbic acid deficiency.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1992

Formation of reductive metabolite, 2-sulfamoylacetylphenol, from zonisamide in rat liver microsomes.

Zonisamide (1,2-benzisoxazole-3-methanesulfonamide) was metabolized to its reductive product, 2-sulfamoylacetylphenol, in rat liver microsomes under anaerobic conditions. The rate of NADPH-dependent reaction was much more rapid than that of NADH-dependent reaction. Furthermore, synergistic effect of NADH on NADPH-dependent reaction was not observed. The optimal formation of 2-sulfamoylacetylphenol from zonisamide in the presence of NADPH was observed around pH 7.0. Cimetidine showed an inhibitory effect on the formation of 2-sulfamoylacetylphenol in a dose-dependent manner. The reductive metabolism of zonisamide was almost completely inhibited by carbon monoxide, and was increased by pretreatment of rats with phenobarbital and pregnenolone 16 alpha-carbonitrile but not by pretreatment with ethanol, 3-methylcholanthrene and imidazole. These results suggest that phenobarbital- and pregnenolone 16 alpha-carbonitrile-inducible form(s) of cytochrome P-450 is responsible for the reductive metabolism of zonisamide to 2-sulfamoylacetylphenol in rat liver microsomes.

Anaerobiosis↗

PubMed1992

[An attempt at intraoperative, ultrasound-guided microwave tissue coagulation for metastatic liver tumors].

Using a microwave tissue coagulator, we attempted intraoperative, ultrasound-guided cauterization and thermocoagulation of metastatic liver tumors. The procedure, safety and efficacy of this therapy were analyzed. During the past 2 years, this therapy was used in 10 patients with unresectable metastatic liver tumors. During surgery, monopolar electrodes were inserted with an ultrasonic guide. One round of cauterization lasted for 10 seconds at 100 W. It was repeated until the tissue around the tumor became hyperechoic. This therapy was used for 67 tumor lesions in total (2-22 lesions/patient). No complications were observed during or after this therapy, except for a case complicated by liver abscess. The anti-tumor effect of the therapy was assessed by histological examination of resected liver tissues. Tumor coagulation and necrosis were observed consistent with the cauterized area. The response to this therapy, assessed by diagnostic imaging, was CR (complete remission) in 3 cases, PR (partial remission) in 3, NC (no change) in 3 and PD (progressive disease) in 1. Thus, the efficacy (the percentage of cases showing CR or PR) was 60%. Since this therapeutic approach acts directly on tumors and is simple and safe, it seems to provide a useful means for intraoperative regional treatment of tumors.

Adult↗

PubMed1991

Physiologic and anatomic assessment of patients with rectocele.

Clinical, physiologic, and anatomic assessments were carried out in 22 female patients with symptomatic rectocele (Group A), 15 patients with asymptomatic rectocele (Group B), and 14 subjects having no rectocele (Group C). Resting and pressure, rectal pressure, rectal compliance, anorectal inhibitory reflex, and rectal sensation did not differ among the groups. Proctography revealed that the lengths of the rectocele during attempted defecation in groups A (1.6 [1.0-3.5] cm) (median and range) and B (1.6 [1.0-3.0] cm) were significantly greater than that in Group C (0.4 [0.1-0.9] cm) (P less than 0.001 in both groups). Median pelvic floor descent at rest in Groups A (4.3 [1.6-7.5] cm) (median and range) and B (4.3 [1.3-6.9] cm) were significantly greater than that in Group C (2.5 [1.2-5.0] cm) (P less than 0.001 and P less than 0.02, respectively). These results indicate that rectocele is not associated with any physiologic change apart from a significant increase of pelvic floor descent.

Adult↗

PubMed1991

Evaluation of a newly devised three-lead Holter recording during treadmill testing in the diagnosis of ischemic ST changes.

Sixty-five patients (54 men, 11 women) with angina pectoris were studied using a technique for recording a 3-lead electrocardiogram without increasing the number of channels and electrodes in the commercial 2-channel Holter recorder. In 52 of the 65 patients, simultaneous ECGs with both the 3-lead Holter method and the conventional 12-lead system during treadmill exercise testing were performed. The results of the two systems in detecting significant ST depressions were consistent in 51 of 52 patients (98%). Twenty-seven of the 32 patients with significant coronary stenosis showed ST depressions during exercise both in the 3-lead Holter and the 12-lead ECG systems. There were cases in which ST depressions were confined only to the CM2 lead (n = 1), the CM5 lead (n = 18) or the CMf lead (n = 3). This indicates that at least three leads are needed in the Holter system for the detection of certain ST changes. The sensitivity of the Holter system during exercise in detecting significant coronary artery disease was the same as that of the 12-lead system (84%). Two of the total 65 patients had variant angina at night. No ST changes in the CM5 lead were observed in either case. Thus, the 3-lead Holter monitoring technique is as accurate as the 12-lead system for the detection of ischemic ST depressions associated with coronary stenosis and is unlikely no miss the signs of variant angina. In addition, this technique is expandable since it can continuously switch between leads using the same channel.

Adult↗

PubMed1991

The in vitro effects of lipid peroxidation on the content of individual forms of cytochrome P-450 in liver microsomes of guinea-pigs.

The effect of lipid peroxidation in vitro on the amounts of several forms of cytochrome P-450 in liver microsomes from guinea-pigs was investigated. Lipid peroxide formation in liver microsomes from ascorbic acid (VC)-deficient animals was much higher than that observed in control animals. The antibodies to rat P-450IA2 (P-448-H), P-450IIB1 (P-450b) and human P-450IIIA4 (P-450NF) recognized one or two forms of cytochrome P-450 in liver microsomes of guinea-pigs. Neither cytochrome P-450 cross-reactive with anti-P-450IIB1 antibodies nor cytochrome P-450 cross-reactive with antibodies to P-450IIIA4 was virtually affected by microsomal lipid peroxidation induced by NADPH in vitro. In contrast, the forms of cytochrome P-450 immunochemically related to P-450IA2 were decreased with the increased level of lipid peroxide formation. The form-specific degradation of cytochrome P-450 due to lipid peroxidation was in agreement with our previous observation that the amounts of cytochrome P-450 cross-reactive with antibodies to P-450IA2 but not with antibodies to P-450IIIA (P-450PB-1) were predominantly decreased in VC-deficient guinea-pigs compared to control animals in vitro.

Animals↗

PubMed1991

Purification and characterization of acidic form of glutathione S-transferase in human fetal livers: high similarity to placental form.

An acidic form of glutathione S-transferase (GST) was purified from human fetal livers by means of affinity chromatography and chromatofocusing. The major peak of the acidic form of GST was focused between pH 4.8 and 4.9. Judging by SDS-PAGE, the purified acidic GST was apparently homogeneous; the subunit molecular weight was estimated to be 23,000. The acidic GST catalyzed the conjugations of glutathione (GSH) with 1-chloro-2,4-dinitrobenzene (CDNB) and ethacrynic acid (EA). The immunochemical properties of the purified acidic GST were indistinguishable from those of human placental GST-pi. The N-terminal amino acid sequence of the acidic GST was identical with that of GST-pi from human placenta. The level of expression of the acidic form of GST was clearly different between human adult and fetal livers as examined on the levels of mRNA and protein.

Amino Acid Sequence↗