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H Sakurai

Publications and source records attributed to H Sakurai.

At least 379 records · Page 21Linked to original sources
PubMed1994

Expression of transforming growth factor-beta 1 and its relation to endomysial fibrosis in progressive muscular dystrophy.

Progressive muscular dystrophy is characterized by muscle fiber necrosis, regeneration, and endomysial fibrosis. Although absence of dystrophin has been known as the cause of muscle fiber degeneration, pathogenesis of interstitial fibrosis is still unknown. Transforming growth factor-beta 1 (TGF-beta 1) induces accumulation of extracellular matrix in various diseases, such as liver cirrhosis and interstitial pneumonitis. To investigate its function on the pathogenesis of progressive muscular dystrophy, it was necessary to determine the degree of TGF-beta 1 expression and the site of TGF-beta 1 immunoreactivity. In Duchenne muscular dystrophy and most of Becker muscular dystrophy, high TGF-beta 1 immunoreactivity expressed on muscle fibers and extracellular space. In other myopathies with endomysial fibrosis, however, TGF-beta 1 was seldom observed. We also examined the immunoreactivity of the latent TGF-beta binding protein, which is bound to the TGF-beta precursors. In all Duchenne muscular dystrophy and half of Becker muscular dystrophy cases, high latent TGF-beta 1 binding protein immunoreactivity was seen, but in other myopathies its immunoreactivity was seldom seen on muscle fibers or extracellular space. Therefore TGF-beta 1 may play an important role in synthesis and accumulation of extracellular matrix in progressive muscular dystrophy.

Animals↗
PubMed1993

Superoxide dismutase mimetic activities of metal complexes of L-2(2-pyridyl)-1-pyrroline-5-carboxylic acid (pyrimine).

We previously isolated the strain Z-54 (Serratia marcescens O5:H1) which produces a reddish-violet pigment. The structure of this pigment was confirmed to be that of a peptide complex containing Fe2+ and L-2(2-pyridyl)-1-pyrroline-5-carboxylic acid (pyrimine), as a chromophore. We measured the superoxide dismutase mimetic activities for the pyrimine-metal complexes by xanthine oxidase/nitroblue tetrazolium and cytochrome c methods and found that the pyrimine-Cu2+ (2:1) complex shows the highest activity yet reported (IC50 = 0.11 microM) among the complexes tested. Pyrimine-Cu+, -Fe2+ and -Mn2+ complexes also gave relatively high SOD mimetic activities. ESR spectra observed for pyrimine-Cu2+ (4:1) showed the structure of the Cu(2+)-complex to be tetrahedral and coordinated with four nitrogen atoms. These results support the idea that the pyrimine-metal complexes might be potent SOD mimics.

Animals↗
PubMed1993

Yeast GAL11 protein is a distinctive type transcription factor that enhances basal transcription in vitro.

The yeast auxiliary transcription factor GAL11, a candidate for the coactivator, was partially purified from yeast cells, and its function was characterized in a cell-free transcription system. The partially purified GAL11 protein stimulated basal transcription from the CYC1 core promoter by a factor of 4-5 at the step of preinitiation complex formation. GAL11 protein also enhanced transcription activated by general regulatory factor 1, GAL4-AH, or GAL4-VP16 to the same extent as the basal transcription. Therefore, the apparent potentiation of the activators by GAL11 was attributable to the stimulation of basal transcription. The wild-type GAL11 protein (but not a mutant-type protein) produced in bacteria stimulated transcription as effectively as GAL11 from yeast. These results suggest that GAL11 functions as a positive cofactor of basal and activator-induced transcription in a cell-free transcription system.

Cell Nucleus↗
PubMed1993

Copper-metallothionein distribution in the liver of Long-Evans cinnamon rats: studies on immunohistochemical staining, metal determination, gel filtration and electron spin resonance spectroscopy.

Distribution of metallothionein (MT) and copper ion (Cu) in the liver of LEC (Long-Evans Cinnamon) rats was investigated to examine the relationship between Cu-MT induction and the development of hepatitis followed by hepatocellular carcinomas. Immunohistochemical studies on MT in the liver of LEC rats indicated that MT is accumulated in nuclei and cytosols. Both MT and Cu, estimated by radioimmunoassay and flameless atomic absorption spectrometry, respectively, in subcellular fractions of the liver were found to be concentrated highest in cytosols, followed by nuclei, mitochondria and microsomal fractions. Gel-filtration (Sephadex G-75) studies demonstrated that MT is induced as the Cu-MT form. Furthermore, the Cu-MT fragment purified by the gel-filtration contains the Cu(I)-MT form, as demonstrated by ESR (electron spin resonance) measurements at 77K. These results will be important for understanding the development of hepatitis in LEC rats.

Animals↗
PubMed1993

Cytochrome P-450-butyl peroxide complex detected by ESR.

ESR measurements were performed for the reaction systems composed of t- or n-butylhydroperoxide and cytochrome P-450 (UT-2), purified from rat liver microsomes. On addition of n-butylhydroperoxide to the P-450 at pH 7.4, ESR signal due to a ferric low-spin species (g1 = 2.29, g2 = 2.24 and g3 = 1.96) was recorded. The observed g-parameters agreed well with those of a model thiolate-heme-iron(III)-peroxide complex, Fe(III)TPP(-S-TGE) (-OO-t-butyl) (g1 = 2.285, g2 = 2.198 and g3 = 1.959). In terms of the g-parameters, the new P-450 complex was concluded to be a P-450-butyl peroxide adduct, in which a butyl peroxide anion ligates at the sixth position of heme iron(III).

Animals↗
PubMed1993

Interrelationship between autoepitope, DNA-binding domain, and CRP-binding domain on a histone H1 molecule.

The interrelationship between autoepitopes, DNA-binding domains, and C-reactive protein (CRP)-binding domains on a histone H1 molecule was examined using fusion proteins of beta-galactosidase and truncated histone H1 molecules. At least two CRP-binding sites were detected on a histone H1 molecule. Site 1 was composed of approximately 25 amino acids and calcium ion was required for the binding of CRP. Site 2, composed of approximately 20 amino acids and not requiring calcium ion, was identical or located very close to a DNA-binding domain and an epitope of anti-histone H1 autoantibodies in SLE sera. These data suggest that, at physiological ionic strength, histone H1 of either free or immune-complexed form could bind to CRP via site 1. These data are discussed with respect to the possible role of CRP in the handling and clearance of immune complexes in patients with systemic lupus erythematosus.

Autoantigens↗
PubMed1993

Quality assurance of biological monitoring in view of risk management.

Since recommended occupational exposure limits both for workplace air concentration and biological monitoring results generally have very narrow margin of protection, the probability of the false decision due to measurement error should be perceived and carefully controlled. Japan Federation of Occupational Health Organization has conducted large scale quality control programs since 1987 and reported the results in detail. The meta-analysis of the report of 1992 made it clear that the qualities of the analysis of the leading laboratories as expressed by the coefficient of variation of measurement error are mostly about 5% or less. It was suggested that the warning level should be set at (biological exposure limits minus 2 SD of the measurement error). However, it will not be needed when the SD is less than 2.5% as was found for the analyses of blood lead, urinary hippuric acid, methyl hippuric acid, and mandelic acid by a few best performing laboratories.

Environmental Monitoring↗
PubMed1993

Effects of energy restriction on age-associated changes of DNA methylation in mouse liver.

DNA methylation is known to change with age in several mammalian species. Here we have examined the effect of dietary energy restriction on this age-associated change in liver DNA of C3H/SHN mice. The total 5-methyldeoxycytidine level in the genome decreased slightly soon after energy restriction started. The effect, however, diminished with time and no appreciable difference was detected at middle and old ages. The degree of methylation at the c-myc gene, on the other hand, was not affected by energy restriction at early periods, but the age-dependent alterations at later ages were repressed. This is a new finding to show that DNA methylation is one of the molecular indices of aging affected by energy restriction. It suggests an importance of DNA methylation in the aging process.

Aging↗
PubMed1993

Biological significance of DNA methylation in the ageing process.

In order to understand the possible importance of DNA methylation in ageing, characteristics of its age-associated changes were examined in mouse and man. The total methylated deoxycytidine level in the genome decreased in the senescent period in mouse liver, but not in mouse brain and human liver. The examination of DNA methylation in each individual gene revealed that only a few genes showed alteration in the senescent phase while many genes change in the maturation period. The alterations were gene- and tissue-specific. Comparison of short-living mouse and long-living man for the age-associated changes of the c-myc gene methylation revealed that the rate of change in mouse was about 20 times faster than that in man. This suggests a deep involvement of DNA methylation in ageing. Further investigations into the causes and consequences of the changes would clarify a basic mechanism of ageing.

Animals↗
PubMed1993

Gonadotrope responsiveness in orchidectomized sheep. II. Effect of gonadotropin-releasing hormone amplitude shift during continuous infusion of estradiol.

Gonadotropin secretion during continuous infusion of estradiol (E2; 5 micrograms/h, i.v.) and pulsatile delivery of GnRH was assessed in orchidectomized sheep (wethers). Wethers received 200 ng GnRH per hourly pulse during the first 12 h of E2 infusion. During the final 36 h of infusion, animals (n = 6/group) received 0, 200, 400, 800, or 1600 ng GnRH/h pulse. Amplitude shift to 1600 ng GnRH/h pulse induced preovulatory surge-like secretion of LH in animals receiving concurrent E2 infusion. In the absence of E2, the same change in GnRH amplitude did not significantly affect serum concentrations of LH. Full expression of the GnRH-induced surge of LH in wethers required prior exposure to E2, but was not dependent on pretreatment with low-amplitude GnRH stimulus. In a companion experiment, anterior pituitary tissue was collected from E2-treated wethers 0, 3, 6, 12, or 24 h after initiation of episodic GnRH delivery (1600 ng/h pulse). Treatment with E2 induced a 5-fold increase in GnRH receptor concentration. The tissue concentration of GnRH receptor was depressed (p < 0.05) within 6 h of initiation of high-amplitude GnRH stimulation and remained depressed for the duration of GnRH delivery. Tissue stores of LH were increased (P < 0.05) by E2 and reduced (p < 0.05) after 3 h of high-amplitude GnRH stimulation. In contrast, tissue stores of FSH were reduced (p < 0.05) by both E2 alone and E2 with concurrent high-amplitude GnRH stimulation. The concentration of mRNA for the FSH beta subunit, but not for the alpha or LH beta subunits, was reduced (p < 0.05) by E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Gonadotrope responsiveness in orchidectomized sheep: III. Effect of estradiol withdrawal after continuous infusion.

The magnitude of GnRH-induced (1600 ng/hourly pulse for 24 h) preovulatory surge-like secretion of LH was assessed in orchidectomized sheep (wethers) during infusion of estradiol (E2, 5 micrograms/h in 10% ethanol-saline [vehicle]) or at 0, 12, 24, or 48 h after E2 withdrawal (n = 6 wethers/group). In one group, infusion of E2 was continued for 48 h, with concurrent circhoral delivery of GnRH during the final 24 h of the E2 delivery period. In other treatment groups, infusion of E2 or vehicle was continued for 24 h. Circhoral delivery of GnRH was initiated at the conclusion of E2 delivery or 12, 24, or 48 h thereafter, or at 48 h after cessation of vehicle infusion. Total GnRH-induced LH secretion in wethers receiving concurrent E2 was significantly augmented relative to the GnRH-induced secretory response in wethers receiving vehicle alone. The magnitude of GnRH-induced LH release was significantly reduced in animals in which E2 delivery was halted at the beginning of the GnRH challenge period. Further reductions in gonadotrope responsiveness were noted 12, 24, and 48 h after cessation of E2 delivery. Responsiveness 48 h after halting the E2 infusion did not differ (p > 0.05) from the responsiveness of wethers that had not been treated with E2. In a companion study, anterior pituitary tissue was collected at the end of E2 infusion (5 micrograms/h for 24 h) or at 12, 24, or 48 h thereafter (n = 6 wethers/group). Anterior pituitary tissue of control animals (n = 6) was collected after halting the infusion of vehicle alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Establishment and characterization of a rat yolk sac tumor cell line, NMT-1, producing alpha-fetoprotein, with potential for lymphatic metastasis.

A new cell line producing alpha-fetoprotein, designated NMT-1, was established from rat yolk sac tumor with the potential for lymphatic metastasis in inbred Wistar rats. In this paper, we investigated the characteristics of NMT-1 cells. The cell line grew in a monolayer and had a polygonal epithelioid appearance in phase-contrast microscopy. The doubling time of NMT-1 cells during exponential growth was approximately 16 h in RPMI-1640 with 10% fetal calf serum. The D0 value for radiation sensitivity was 97 +/- 3 cGy. The extrapolation number, n, for NMT-1 was 1.08 +/- 0.15. In the log phase, the G0/G1, S and G2/M fractions were 23.2%, 62.1% and 14.3%, respectively. Tumor take was observed in all of the rats inoculated with NMT-1 cells. In the case of flank tumor, the mean survival time was 104 days after inoculation with 10(6) tumor cells. Inguinal, axillary, paraaortic, mesenteric and mediastinal lymphnode metastases were observed in all rats inoculated with NMT-1 cells. Rats which survived for a long time developed metastases in a lymphatic vessels of the liver, lung and/or kidney microscopically. The biological behavior and the histopathological features of the tumor induced by inoculation with NMT-1 cells were the same as those of the original tumor induced by fetectomy.

Animals↗
PubMed1993

Additive induction of Egr-1 (zif/268) mRNA expression in neuroblastoma x glioma hybrid NG108-15 cells via cholinergic muscarinic, alpha 2-adrenergic, and bradykinin receptors.

Administration of carbachol, noradrenaline, and bradykinin induced Egr-1 mRNA expression within 1 h in mouse neuroblastoma x rat glioma hybrid NG108-15 cells. With specific receptor antagonists, the Egr-1 inductions by carbachol and noradrenaline were shown to be mediated via cholinergic muscarinic and alpha 2-adrenergic receptors, respectively. At their saturation levels for Egr-1 induction, the two agonists had additive effects when added together, but no prolongation of the effect on Egr-1 induction was observed. Addition of carbachol or noradrenaline 6 h after primary stimulation with carbachol or noradrenaline did not result in secondary Egr-1 induction, probably because of receptor desensitization. On the other hand, bradykinin consistently had an additive effect on Egr-1 induction, irrespective of the time of its addition, suggesting that the signal pathways for Egr-1 induction by carbachol or noradrenaline and by bradykinin are different. Treatment of cells with pertussis toxin or cholera toxin strongly inhibited Egr-1 induction by carbachol or noradrenaline but only partially inhibited the induction by bradykinin. Thus, the signals transduced in NG108-15 cells by different neurotransmitter receptors appear to have different effects on Egr-1 induction, depending on the times of stimulation and the combinations of receptors stimulated.

Animals↗
PubMed1993

Comparison of depolarizing and direct current systems on iontophoretic enhancement of transport of sodium benzoate through human and hairless rat skin.

A direct current (DC) system and a pulsed depolarization (PD) system were evaluated for their iontophoretic permeation of sodium benzoate, as a model drug, through hairless rat and human skin. Approximately the same initial permeation of sodium benzoate through the hairless rat skin was obtained at 0.1 mA for the DC device and at 3.0 mA for the PD device. Study of the drug's permeation was performed using a two-chamber iontophoretic diffusion cell, over two cycles of three successive on-off experimental conditions [stage I (off) 0-4 h, II (on) 4-6 h, III (off) 6-10 h, saline washing 10-24 h, IV (off) 24-28 h, V (on) 28-30 h and VI (off) 30-34 h]. Skin permeation rate during stage IV of the iontophoresis as compared with the control group through hairless rat or human skin for the DC system was 2-4 times that in stage I, whereas in the same stage using the PD system it was almost the same as in stage I. Impedance of skin decreased during the application of either system (stage II); however, the value significantly recovered during stage III only in the case of the PD system use on human skin. Histological observation revealed no tissue alteration in the hairless rat skin after using either system. When the DC or PD system was applied to volunteers, the minimum current density producing pain was 0.016 or 2.7 mA cm-2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗