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Biomedical subjects

T Hidaka

Publications and source records attributed to T Hidaka.

At least 109 records · Page 6Linked to original sources
PubMed1996

Polyembryony in Citrus. Accumulation of seed storage proteins in seeds and in embryos cultured in vitro.

Citrus exhibits polyembryonic seed development, an apomictic process in which many maternally derived embryos arise from the nucellus surrounding the developing zygotic embryo. Citrus seed storage proteins were used as markers to compare embryogenesis in developing seeds and somatic embryogenesis in vitro. The salt-soluble, globulin protein fraction (designated citrin) was purified from Citrus sinensis cv Valencia seeds. Citrins separated into two subunits averaging 22 and 33 kD under denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A cDNA clone was isolated representing a citrin gene expressed in seeds when the majority of embryos were at the early globular stage of embryo development. The predicted protein sequence was most related to the globulin seed storage proteins of pumpkin and cotton. Accumulation of 33-kD polypeptides was first detected in polyembryonic Valencia seeds when the majority of embryos were at the globular stage of development. Somatic Citrus embryos cultured in vivo were observed to initiate 33-kD polypeptide accumulation later in embryo development but accumulated these peptides at only 10 to 20% of the level observed in polyembryonic seeds. Therefore, factors within the seed environment must influence the higher quantitative levels of citrin accumulation in nucellar embryos developing in vivo, even though nucellar embryos, like somatic embryos, are not derived from fertilization events.

Amino Acid Sequence↗
PubMed1996

Pharmacokinetics of KRM-1648, a new benzoxazinorifamycin, in rats and dogs.

The pharmacokinetics of 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl) benzoxazinorifamycin (KRM-1648) in rats and dogs given a single oral dose of 3, 30, or 100 mg/kg of body weight were studied. In the rats, the concentrations of KRM-1648 in plasma, whole blood, and tissues peaked between 2.0 and 24.0 h, with elimination half-lives ranging from 6.2 to 19.5 h. The peak concentrations and the areas under the concentration-versus-time curves (AUC) for whole blood and tissues were 2 to 277 times higher than those for plasma. The high levels of KRM-1648 in tissues were consistent with its large volume of distribution (in excess of 10 liters/kg). A nonlinear increase in peak concentrations and AUCs for plasma, whole blood, and tissues occurred as the dose was increased and was consistent with the dose-dependent decrease in bioavailability. In the dogs, KRM-1648 levels in plasma and whole blood also exhibited a late time to the peak concentration (ranging from 4.0 to 11.2 h), a long elimination half-life (ranging from 15.2 to 24.0 h), and nonlinear kinetics. KRM-1648 exhibited high levels of plasma protein binding (more than 99%) and a high degree of affinity for lipoproteins in the plasma of both animals. After administration of KRM-1648, measurable levels of its metabolites, 25-deacetyl KRM-1648 in rats and 25-deacetyl KRM-1648 and 30-hydroxy KRM-1648 in dogs, were found in the biological samples tested. Thus, KRM-1648 is characterized by a high tissue affinity, a long elimination half-life, and nonlinear pharmacokinetics.

Animals↗
PubMed1996

Clinical features of skin metastasis from lung cancer.

Metastasis to the skin from lung cancer is less common than metastasis to other organs. We clinically reviewed 16 cases of skin metastasis. The incidence of skin metastasis was 2.8% among all 579 cases of lung cancer. Large cell carcinoma showed the greatest tendency to spread to the skin and epidermoid carcinoma showed the least tendency. The most common sites for skin lesions were the back. Almost all lesions ranged from 1 to 5 cm in diameter. Clinical manifestation of skin metastasis was nodular type in all cases. At the development of skin metastasis, all cases were accompanied by metastasis to other organs. There was only a slight response to combination chemotherapy carried out 5 cases for lung cancer, and most lesions were progressive. Median survival after skin involvement was approximately 4 months.

Adult↗
PubMed1996

Cloning and expression of cDNA for soluble form of rat heme oxygenase-1.

Heme oxygenase catalyzes the oxidation of heme to biliverdin and carbon monoxide. The gene encoding the truncated soluble rat heme oxygenase-1 (Metl-Pro267) was cloned. The enzyme protein was expressed in E. coli JM109 and purified to homogeneity. The molecular weight of the recombinant enzyme was 30 kDa as assessed by SDS-polyacrylamide gel electrophoresis. From a 3-L culture, about 90 mg of the purified enzyme was routinely obtained. The dependency of the heme oxygenase reaction catalyzed by the soluble enzyme on the NADPH-cytochrome P-450 reductase concentrations and the effect of catalase on the reaction were examined to compare with the purified membrane-bound form of heme oxygenase-1 (Yoshida and Kikuchi, 1978b). The activity of the soluble enzyme was inhibited at high concentrations of NADPH-cytochrome P-450 reductase and the inhibition was not alleviated by addition of catalase unlike the membrane-bound form. The ferric iron of the heme-heme oxygenase complex was in a typical high spin state at acidic to neutral pH (pH 6.5-7.0) but conversion to low spin state was observed at basic pH (pH 9-10). The heme bound to heme oxygenase was converted to biliverdin at a stoichiometric ratio of unity in the presence of NADPH-cytochrome P-450 reductase system. During the heme degradation of the heme-heme oxygenase complex under atmospheric oxygen, several intermediates, that is, oxygenated heme and verdoheme, were spectrally discriminated.

Animals↗
PubMed1996

Identification and antimicrobial activity of urinary metabolites of a rifamycin derivative in dog.

1. Three metabolites of the antimicrobial agent 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648) were isolated from dog urine obtained after administration of a single oral dose. These metabolites of KRM-1648 were identified by mass spectrometry and 1H and 13C-nmr spectrometry. 2. Three metabolites of KRM-1648 were identified as 25-deacetyl KRM-1648, 30-hydroxy KRM-1648 and 25-deacetyl-30-hydroxy KRM-1648. 3. The antimicrobial activities of 25-deacetyl KRM-1648 were comparable with those of the parent compound, whereas 30-hydroxy KRM-1648 was equipotent and 2-8-fold less active than the parent compound against bacteria and mycobacteria, respectively.

Administration, Oral↗
PubMed1996

In vitro metabolism of a rifamycin derivative by animal and human liver microsomes, whole blood and expressed human CYP3A isoform.

1. In vitro metabolism of a rifamycin derivative, benzoxazinorifamycin KRM-1648, was studied using mouse, rat, guinea pig, dog, monkey and human liver microsomes. 30-Hydroxy-KRM-1648 (M2) was produced in mouse, dog, monkey and human microsomes. 25-Deacetyl-KRM-1648 (M1) was produced in dog and human microsomes, but not in mouse or monkey microsomes. Neither M1 nor M2 was detected in rat or guinea pig microsomes. 2. In dog and human liver microsomes the formation of M2 was dependent on NADPH, but the formation of M1 was not. 3. In vitro metabolism of the parent compound was studied in whole blood in some species. Only M1 was detected in mouse and rat blood, and not in dog and human blood. 4. These findings demonstrated that the metabolite pattern in dog resembled that in man, and suggested that the 30-hydroxylation of KRM-1648 was mediated by cytochrome P450, but that the 25-deacetylation was not. 5. Among the ten recombinant human P450 isoforms used, only the cell lysates including CYP3A3 and CYP3A4 catalysed the M2 formation from KRM-1648.

Animals↗
PubMed1996

Induction of DNA breaks in cardiac myoblast cells by norepinephrine.

We measured DNA single strand breaks (SSB) in cardiac myoblast cells in response to norepinephrine (NE) stimulation. Rat cardiac myoblast cells (H9c2) were stimulated with concentrations of 100 microMs to 1 mM NE for 2, 3, 4, and 12 hours after prior incubation with control solution, bunazosin, propranolol, verapamil, or captopril for 30 min. The DNA damage was measured by fluorometric alkaline elution. The strand scission factor, an index of the severity of SSB, increased slightly after stimulation with 200 microMs NE for 12 hours and with 1 mM NE for 4 hours. This increase was prevented by catalase or superoxide dismutase, which prevent production or accumulation of active oxygen radicals, during the stimulation, but not by pretreatment with a alpha-receptor antagonist, a beta-adrenergic receptor antagonist, a Ca2+ antagonist, or an angiotensin converting enzyme inhibitor. Thus, DNA SSB were induced by NE in cardiac myoblast cells. Certain active oxygen species may contribute to the DNA damage induced by NE.

Adrenergic alpha-Agonists↗
PubMed1996

[In vitro activities of benzoxazinorifamycin KRM-1648 against Mycobacterium tuberculosis].

In vitro antimicrobial activities of the benzoxazinorifamycin derivative KRM-1648 (KRM) against 50 strains of Mycobacterium tuberculosis isolated from patients with mainly intractable pulmonary tuberculosis were studied. MIC90 values of KRM, rifabutin (RBT) and rifampicin (RFP) for RFP-sensitive strains (27 strains; defined as those with MICRFP values of < 1.56 micrograms/ml) were 0.013, 0.1 and 0.4 micrograms/ml, respectively, when determined by the agar dilution method using 7H11 medium. MIC90 values of KRM, RBT, and RFP for RFP-resistant strains (23 strains; defined as those having MICRFP values of > or = 1.56 micrograms/ml) were 100, 12.5 and > 100 micrograms/ml, respectively. MICs of KRM against 50 clinical isolates of M. tuberculosis distributed over a much lower range than those of RFP. KRM showed more potent antimicrobial activity than RBT against the organisms with low MIC values (< or = 1.56 micrograms/ml), while it was not so active as RBT against the organisms with high MIC values (> or = 3.13 micrograms/ml). Cross-resistance between KRM and RFP or RBT was observed for M. tuberculosis.

Antibiotics, Antitubercular↗
PubMed1995

Cloning and nucleotide sequence of fosfomycin biosynthetic genes of Streptomyces wedmorensis.

The biosynthetic pathway for production of the antibiotic fosfomycin by Streptomyces wedmorensis consists of four steps including the formation of a C-P bond and an epoxide. Fosfomycin production genes were cloned from genomic DNA using S. wedmorensis mutants blocked at different steps of the biosynthetic pathway. Four genes corresponding to each of the biosynthetic steps were found to be clustered in a DNA fragment of about 5 kb. Nucleotide sequencing of a large fragment revealed the presence of ten open reading frames, including the four biosynthetic genes and six genes with unknown functions.

Acetaldehyde↗
PubMed1995

Sequence of a P-methyltransferase-encoding gene isolated from a bialaphos-producing Streptomyces hygroscopicus.

The nucleotide sequence of the Streptomyces hygroscopicus gene encoding P-methyltransferase, catalyzing the formation of a carbon-phosphorus bond, involved in bialaphos biosynthesis, has been determined. The amino-acid sequence deduced from the nt sequence, shows homology with those of magnesium-protoporphyrin IX monomethyl ester oxidative cyclase (Mg-ProtoMe cyclase) of Rhodobacter capsulatus and the enzyme catalyzing the methylation of the aldehyde carbon of phosphonoacetaldehyde in fosfomycin biosynthesis.

Amino Acid Sequence↗
PubMed1995

The carboxyphosphonoenolpyruvate synthase-encoding gene from the bialaphos-producing organism Streptomyces hygroscopicus.

The nucleotide (nt) sequence of the Streptomyces hygroscopicus gene encoding carboxyphosphonoenolpyruvate (CPEP) synthase, that catalyzes a transesterification between phosphoenolpyruvate (PEP) and phosphonoformate (PF) in the bialaphos biosynthetic pathway, has been determined. The amino-acid sequence deduced from the nt sequence is similar to several eukaryotic 2-phospho-D-glycerate hydrolases (EC 4.2.1.11).

Amino Acid Sequence↗
PubMed1995

Therapeutic effect of KRM-1648 with various antimicrobials against Mycobacterium avium complex infection in mice.

A new benzoxazinorifamycin, KRM-1648 (KRM), was studied for its therapeutic efficacy in combination with other antimicrobials against Mycobacterium avium complex infections in mice. When M. intracellulare-infected (intravenously) mice were given KRM, clarithromycin (CAM), sparfloxacin (SPFX), or ethambutol (EB) each alone or in combination, by gavage, once daily 6 times per week (streptomycin [SM] was given subcutaneously twice per week) from day 1, KRM + CAM exhibited combined efficacy in terms of reducing the incidence of gross lung lesions and the bacterial loads in the lungs and spleens. The addition of either EB or EB + SPFX to KRM + CAM increased the efficacy. Moreover, the multi-drug regimen of KRM + CAM + EB + SPFX or ofloxacin [OFLX]) was more efficacious than rifampicin (RMP) + CAM + EB + SPFX (or OFLX). In M. avium infection, KRM + clofazimine was the most efficacious among two-drug combinations tested followed by KRM + SM. KRM + CAM was considerably less effective against M. avium than against M. intracellulare infection. KRM + EB and KRM+OFLX failed to show such a combined effect.

Animals↗
PubMed1995

In vitro and in vivo activities of the benzoxazinorifamycin KRM-1648 against Mycobacterium tuberculosis.

The in vitro and in vivo activities of a new benzoxazinorifamycin, KRM-1648 (KRM), against Mycobacterium tuberculosis were studied. The MIC at which 50% of the isolates are inhibited (MIC50) and the MIC90 of KRM for 30 fresh isolates of M. tuberculosis measured by the BACTEC 460 TB System were 0.016 and 2 micrograms/ml, respectively. These values were much lower than those for rifampin (RMP), which were 4 and >128 micrograms/ml, respectively, and considerably lower than those for rifabutin (RBT), which were 0.125 and 8 micrograms/ml, respectively. A correlational analysis of the MICs of these drugs for the clinical isolates revealed the presence of cross-resistance of the organisms to KRM and either RMP or RBT although the MICs of KRM were distributed over a much lower range than were those of the other two drugs. KRM and RMP at concentrations of 1 to 10 micrograms/ml almost completely inhibited the bacterial growth of RMP-sensitive strains (H37Rv, Kurono, and Fujii) of M. tuberculosis phagocytosed in macrophage-derived J774.1 cells. KRM was more active than RMP in inhibiting the growth of the RMP-resistant (MIC = 8 micrograms/ml) Kurata strain but failed to show such an effect against the RMP-resistant (MIC >128 micrograms/ml) Watanabe stain. When KRM was given to M. tuberculosis-infected mice at dosages of 5 to 20 mg/kg of body weight by gavage, one daily six times per week from day 1 after infection, it was much more efficacious than RMP against infections induced in mice by the RMP-sensitive Kurono strain, as measured by a reduction of rates of mortality, a reduction of the frequency and extent of gross lung lesions, histopathological changes in lung tissues, and a decrease in the bacterial loads in the lungs and spleens of infected mice. KRM also displayed significant therapeutic efficacy against infection induced by the RMP-resistant Kurata strain, while neither KRM nor RMP was efficacious against infection by the RMP-resistant Watanabe strain. In the case of infection with the Kurono strain, the efficacy of the drugs in prolonging the time of survival was in the order KRM, RBT, RMP. KRM was much more efficacious than RMP, when given at 1- to 4-week intervals. These findings suggest that KRM may be useful for the clinical treatment of tuberculosis contracted through RMP-sensitive strains, even when it is administered at long intervals.

Animals↗
PubMed1995

Differential effects of geometrical isomers of octadecadienoic acids on ketogenesis and lipid secretion in the livers from rats fed a cholesterol-enriched diet.

The effect of cis,cis (cc)- and trans,trans (tt)-9,12-octadecadienoic (18:2) acids on ketogenesis and lipid secretion was compared in isolated perfused livers from cholesterol-fed rats. The hepatic uptake of 18:2 acids was comparable in both isomers. The livers perfused with cc-18:2 acid in comparison with those perfused without fatty acid substrate produced approximately 4-fold more ketone bodies accompanying the rise of the beta-hydroxybutyrate:acetoacetate ratio, while the tt-acid isomer further increased these parameters. The hepatic secretion rates of triglyceride and phospholipid as well as cholesterol were all elevated on perfusing the cc-18:2 acid as compared to without fatty acid. In contrast, the rates observed with the tt-18:2 acid isomer except for phospholipid were intermediate, indicating a reciprocal response in ketogenesis and lipid secretion by the trans isomer. The rate of incorporation of trans-fatty acid into perfusate triglyceride and cholesterol ester were lower than cis-acid, but vice versa into perfusate phospholipids. On the other hand, the effects of trans-fatty acid on the concentration and composition of hepatic lipids were less clear. These results emphasize the differential effect of geometrical isomers of the 18:2 acids on oxidation and esterification even in the livers containing a high level of cholesterol.

3-Hydroxybutyric Acid↗
PubMed1995

[Hemodynamic and neurohumoral effects of carperitide (alpha-human atrial natriuretic peptide) in dogs with low-output heart failure].

We examined the hemodynamic and neurohumoral effects of carperitide in dogs with low-output heart failure (LHF) produced by volume expansion, ligation of the left anterior descending coronary artery and methoxamine infusion. Carperitide (0.1 approximately 1 micrograms/kg/min, i.v. infusion for 30 min) decreased pulmonary arterial pressure, right atrial pressure and systemic vascular resistance and increased cardiac output. These pharmacological activities were equivalent to those of nitroglycerin (NG, 3 micrograms/kg/min). Although most of the animals did not excrete urine after induction of LHF, carperitide, unlike NG, increased urine volume. The plasma level of cyclic GMP was elevated about three times by induction of LHF and further increased after treatment with carperitide (1 microgram/kg/min). Carperitide had no effects on plasma renin activity, plasma aldosterone concentration and plasma noradrenaline. These results taken together indicate that carperitide reduces both preload and afterload in association with an increase in cyclic GMP production and improves the untoward hemodynamic alterations in LHF dogs.

Acute Disease↗
PubMed1995

Augmentation and suppression of the excitatory and inhibitory neuromuscular transmission induced by the ionophores, X-537A and A23187, in the red muscle of carp, Cyprinus carpio.

The effects of the ionophores, X-537A and A23187, on excitatory junction potentials (ejp), inhibitory junction potentials (ijp), diphasic junction potentials (diphasic jp) composed of ejp and ijp, and miniature excitatory junction potentials (mejp) were examined in the red muscles of carp, Cyprinus carpio. When 25 microM X-537A and 5 microM A23187 were applied, the amplitude of ejp and ijp increased transiently, then decreased gradually, and finally disappeared. The duration of ejp and ijp was little affected by the ionophores. The ionophores induced a transient increase in the frequency of mejp, which then decreased gradually after the maximum increase was attained, and finally fell below the control level. The ionophores had little effect on the resting membrane potential, membrane resistance of the muscle fiber, and amplitude of the compound action potential recorded from nerve bundles innervating this muscle. The ionophores caused ACh-evoked potentials to decrease gradually and finally disappear. These results suggest that the increase in the amplitude of ejp and ijp and in the frequency of mejp might be mainly due to the augmentation of ACh release from nerve terminals caused by an elevation of the intracellular Ca2+ concentration. On the other hand, the decrease and the abolition in the amplitude of ejp and ijp and in the frequency of mejp might be mainly due to the desensitization of the postsynaptic membrane.

Animals↗
PubMed1995

Inhibition of the multiplication of Mycobacterium leprae in nude mice by intermittent administration of a new rifamycin derivative, 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648) combined with sparfloxacin.

Inhibition of the multiplication of Mycobacterium leprae in the footpads of nude mice by the oral administration of sparfloxacin, a new quinolone, and 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648), selected from a series of newly synthesized benzoxazinorifamycins, was studied. When the 2 drugs were administered alternately at intervals of 3 or 4 days, (i.e., each drug was administered once weekly), or simultaneously once weekly, between 3 and 5 months after inoculation of nude mice with M. leprae, 10 mg sparfloxacin and 0.6 mg KRM-1648 per kg bodyweight were sufficient to prevent multiplication of the organisms. Only partial inhibition of multiplication was achieved by alternate administration of 5 mg sparfloxacin and 0.3 mg KRM-1648 per kg, as was the case for 20 mg sparfloxacin per kg or 1 mg KRM-1648, each drug administered alone once weekly. The addition to these 2 drugs of dapsone, administered in the diet in a concentration of 0.001 g per 100 g, enhanced their effect. The potential usefulness of multidrug regimens including these compounds is considered.

Administration, Oral↗