Search PubMed⌕ Search

Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 757 records · Page 42Linked to original sources
PubMed1987

Nucleotide sequence of a human liver cytochrome P-450 related to the rat male specific form.

P-450 human-2 is a human cytochrome P-450 that is immunochemically related to a constitutive male-specific cytochrome P-450 (P-450-male) and the phenobarbital-inducible P-450b/e in rat liver. By screening a human liver cDNA library in bacteriophage lambda gt11, we isolated a clone with an insert length of 1,847 bases (pHY13). The clone was sequenced and shown to code for a protein of 487 amino acids. The N-terminal 11-amino-acid sequence was in agreement with the protein sequence of P-450 human-2. The nucleotide sequence of pHY13 showed less than 50% similarity with those of human cytochrome P-450s, pHP-450(1), HLp, P-450NF, P1-450 4, and P3(450), but the nucleotide sequence of pHY13 is 80% similar to the reported sequence of rat cytochrome P-450, P-450(M-1). In addition, the coding sequence of pHY13 showed close similarity to that of MP-8, which was recently reported as the sequence corresponding to human cytochrome P-450MP, although no apparent similarity was observed in their 3' non-coding sequences except for the first 75 bases and the expected length of the complete sequences. These results, together with the immunochemical data, indicate that P-450 human-2 is closely related, but not identical, to P-450MP, and may belong to the category of developmentally regulated constitutive cytochrome P-450s.

Amino Acid Sequence↗
PubMed1987

Electronmicroscopic study on biopsied rectal mucosa in adrenoleukodystrophy.

Rectal mucosal biopsies were performed for seven members of five families with adrenoleukodystrophy (ALD). Many histiocytes contained characteristic cytoplasmic lamellar inclusions that were identical to those seen in adrenocortical cells, brain macrophages, and Schwann cells of affected patients. The ultrastructural features were seen in all patients and also in two asymptomatic younger brothers who had presymptomatic ALD according to assay of very-long-chain fatty acids.

Adrenoleukodystrophy↗
PubMed1987

Further studies on the persistence of neonatal androgen imprinting on sex-specific cytochrome P-450, testosterone and drug oxidations.

Neonatal castration completely suppressed the expression of P-450-male and expressed P-450-female; and testosterone treatment in a neonatal period partially reversed the effect of castration, i.e., neonatal imprinting (Kamataki et al., 1984; Waxman et al., 1985). In the present communication, we investigate the reversibility and persistency of neonatal imprinting on the expression of P-450-male and P-450-female. To our surprise, testosterone treatment at adulthood (8 weeks old) caused full expression of P-450-male and restored the activities of 2 alpha- and 16 alpha-testosterone hydroxylases in neonatally castrated rats. The levels of ethylmorphine N-demethylation, propoxycoumarin O-depropylation and benzo(a)pyrene hydroxylation were increased to the levels of adult male rats by adult testosterone-treatment. Moreover, treatment with testosterone of neonatally castrated rats at the age of 19 weeks did not cause a complete recovery of P-450-male content and drug-metabolizing activities. Testosterone administration into neonatal female rats did not significantly alter the contents of sex-dependent cytochrome P-450 and drug and steroid metabolizing activities in adulthood. Additional testosterone treatment in adulthood only slightly affected these parameters. All these results indicate that neonatal androgen imprinting on sex-dependent cytochrome P-450 and drug and steroid metabolizing activities in rat liver microsomes is not a permanent programming process and is modified by the presence and absence of sex-steroid hormones.

Androgens↗
PubMed1987

Erythrocyte insulin receptor in insulin autoimmune syndrome: effects of corticosteroid therapy.

Changes in the erythrocyte insulin receptors were studied in a patient with insulin autoimmune syndrome before and after corticosteroid therapy. In this case, despite a quite low fasting plasma glucose value (29 mg/100 ml), a 75 g oral glucose tolerance test (OGTT) showed a diabetic curve and extremely high immunoreactive insulin (IRI) levels were observed. After 6 months duration of the disease, corticosteroid was given to the patient and hypoglycemic attacks disappeared with an improvement of the levels of plasma glucose. The number of insulin receptors decreased from 58 to 29 sites/erythrocyte and an increase in binding affinity or maximal binding ability were observed after the treatment with corticosteroid. These receptor changes, for the most part, might be derived from the steroid effects, since there were similar results when we administered steroid for a long term to a certain disease. There was a 20% reduction in the amount of insulin binding IgG purified from the serum one month after treatment with corticosteroid as compared with that purified from the serum before the treatment. The results suggest the usefulness of corticosteroid therapy in treatment of the insulin autoimmune syndrome.

Aged↗
PubMed1987

Unusual inclusions in mature polymorphonuclear neutrophils of cyclic neutropenia.

The bone marrow of an 11-year-old girl with cyclic neutropenia was examined by electron microscopy. In the nonneutropenic phase, mature polymorphonuclear neutrophils had numerous bundles of filamentous inclusions in both cytoplasms and nucleus. Primary granules were slightly increased in number. Similar filament-like inclusions also have been reported in some cases of hemopoietic dysplasia; however, our case showed no abnormality in chromosomes, no thrombocytopenia, and no leukemic change.

Actin Cytoskeleton↗
PubMed1987

[Epidemiology of neuroblastoma].

From the Childhood Cancer Registry in Japan, incidence of neuroblastoma was 1 among 100,000-150,000 children under the age of 15 years, and 25% of them were under 1 year old. But, mass-screening for this tumor in infancy showed incidence of detection of 1:5,000 babies. Even if we presume that all of the tumor cases--if not screened with the risk of developing later--were detected in infancy, this is more than the expected incidence. To explain this, we postulated 4 patterns in the natural growth of this tumor. After the start of mass-screening, the number of the patients with this tumor in much earlier stage and younger age increased and this was the main cause of improvement of the results of treatment.

Age Factors↗
PubMed1987

The effect of omega-phosphono-alpha-aminocarboxylic acids on seizures and brain amino acid levels in E1 mice.

The omega-phosphono-alpha-aminocarboxylic acids, e.g., 2-amino-5-phosphonopentanoate and 2-amino-7-phosphonoheptanoate, are known to act as potent and selective antagonists at N-methyl-D-aspartate receptors and to have a pronounced anticonvulsant action on a variety of animal models of epilepsy. In the present study, the effects of these omega-phosphono-alpha-aminocarboxylic acids on E1 mice were investigated. These mice are inbred mutant epileptic mice, which are highly susceptible to convulsive seizures upon throwing stimulation. 2-Amino-3-phosphonopropionate injected intraventricularly (at a dose of 1.04 mumol) had a marked anticonvulsant action, but at a lower dose (0.1 mumol), it induced running fits. 2-Amino-4-phosphonobutyrate induced transitory excitation just after the injection, followed by sedation. 2-Amino-5-phosphonopentanoate induced marked behavioral sedation. 2-Amino-6-phosphonohexanoate induced tonic-clonic convulsions and epileptic discharges in electroencephalograms. 2-Amino-7-phosphonoheptanoate showed a strong anticonvulsant action at a dose of 1.27 mumol, but it induced myoclonic seizures at a lower dose. Amino acid analyses of E1 mouse brain showed that 2-amino-3-phosphonopropionate increased the glutamine level, 2-amino-4-phosphonobutyrate decreased the aspartic acid level, 2-amino-5-phosphonopentanoate decreased the glutamic acid level, 2-amino-6-phosphonohexanoate decreased the glutamic acid, glutamine, gamma-aminobutyric acid, glycine and alanine levels, and 2-amino-7-phosphonoheptanoate decreased the glutamic acid label 1 hour after their injection. These findings suggest that the effects of omega-phosphono-alpha-aminocarboxylic acids on the E1 mouse brain are multiple and complicated, depending on the numbers of their carbon chain.

Amino Acids↗
PubMed1986

Evidence for cooperative interactions of myosin heads with thin filament in the force generation of vertebrate skeletal muscle fibers.

To examine the possibility of cooperative interactions between the two myosin heads in muscle contraction, Ca2+-activated force development, K+-EDTA-and Mg2+-ATPase activities, muscle fiber stiffness, and the velocity of unloaded shortening were measured on partially p-phenylenedimaleimide (p-PDM)-treated glycerinated muscle fibers, which contained a mixture of myosin molecules with zero, one, and two of their heads inactivated, and the relationships among these values (expressed relative to the control values) were studied. It was found that the magnitude of the Ca2+-activated isometric force development was proportional to the square of both K+-EDTA- and Mg2+-ATPase activities and also to the square of muscle fiber stiffness. If the two myosin heads in the glycerinated fibers are assumed to react independently with p-PDM, the above results strongly suggest that each myosin molecule in the thick filaments can generate force only when its two heads do not react with p-PDM, muscle fiber stiffness is determined by the total number of native heads, and there is no cooperative interaction between the two myosin heads in catalyzing ATP hydrolysis.

Adenosine Triphosphatases↗
PubMed1986

Hydrophilic-hydrophobic microdomain surfaces having an ability to suppress platelet aggregation and their in vitro antithrombogenicity.

Block copolymers were synthesized by a coupling reaction of hydrophilic chains of poly(2-hydroxyethyl methacrylate) (PHEMA) with hydrophobic chains of polystyrene (PSt), or poly(dimethyl siloxane) (PDMS). Microstructures of films of the block copolymers exhibited a hydrophilic-hydrophobic microphase separated structure. For evaluation of in vivo antithrombogenicity, small diameter tubes (1.5 mm I.D. and 20 cm length) coated by the copolymers on their internal surfaces were implanted in rabbits as arteriovenous shunts. Occlusion times of the tubes, measured by formation of thrombus, were three days for PHEMA, two days for PSt, and three days for PDMS. The block copolymers showed excellent antithrombogenic properties: occlusion times were 20 days for HEMA-St block copolymer and 12 days for HEMA-DMS block copolymers. In vitro examination of polymer-platelet interaction in terms of platelet adhesion and aggregation, which are important initial processes of blood coagulation, demonstrated suppressed adhesion and aggregation on microdomain surfaces constructed of hydrophilic and hydrophobic block copolymers. From both in vivo and in vitro examination, it was concluded that HEMA-St and HEMA-DMS block copolymers showed promising antithrombogenic activities by suppressing activation and aggregation of platelets.

Animals↗
PubMed1986

Suppression of platelet activity on microdomain surfaces of 2-hydroxyethyl methacrylate-polyether block copolymers.

Block copolymers constructed from chains of poly(2-hydroxyethyl methacrylate) (PHEMA) and either poly-ethyleneoxide (PEO) or poly-propyleneoxide (PPO) were synthesized. These block copolymers exhibited microdomain structure. Platelet adhesion on their surfaces was investigated by a column elution method to examine the effect of microdomain structure. The number of platelets adhered from whole blood was smaller for the block copolymer systems than for the homopolymers. Minimum points of platelet adhesion appeared at approximately 0.38 mol fraction of HEMA in the HEMA-PO system. Both block copolymer surfaces showed microdomains of alternate lamellar structure. Furthermore, the percent of platelets released from the column after incubation was investigated using PRP. In the case of homopolymers, released platelet percentages decreased with an increase of incubation time. Released platelet percentages from the block copolymers, however, were nearly constant with changing incubation time. These results show that HEMA-EO and HEMA-PO block copolymers had the ability to suppress both reversible and irreversible adhesion of platelets to their respective microdomain surfaces.

Animals↗