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S Amano

Publications and source records attributed to S Amano.

At least 145 records · Page 8Linked to original sources
PubMed1995

Differential cloning using in-gel competitive reassociation.

We describe the principle and actual processes of a differential cloning procedure designed for cloning of anonymous restriction DNA fragments whose molecular sizes differ between two genomic DNA preparations from higher organisms as a result of DNA rearrangement, polymorphism, etc. The procedure, which was extensively modified from the original one and still employs in-gel competitive reassociation (IGCR) as the basic principle, aims for cloning of DNA fragments which exist in one copy or less per mammalian genome. The modified procedure consists of dissociation and reassociation of biotinylated restriction digests of target DNA fragments (from which clones are to be isolated) in the presence of a large excess of reference (competitor) DNA in gel after electrophoresis, which is followed by absorption of the target DNA fragments to streptavidin-coated tubes and solid-phase polymerase chain reaction. After repeating these steps we attained substantial enrichment of altered DNA fragments which were originally present in one copy or less per complex mammalian genome.

Animals↗
PubMed1995

Long-term observation of in vivo 31P NMR spectra in carbon tetrachloride-intoxicated rabbit liver using implanted wireless surface coil.

Phosphorus-31 NMR spectra in rabbit liver were successively observed for more than 5 months in a chronic CCl4 intoxication model using implanted wireless surface coils. The quality of the obtained NMR spectra was satisfactory and there was sufficient time resolution to follow the dynamic changes that occurred during a fructose tolerance test. The implanted coil did not lead to any serious adverse effects such as infection or liver dysfunction. During an 18-week administration of CCl4, the area of the phosphodiester peak significantly decreased. The ratio of P(i)/beta-ATP was transiently elevated and gradually returned to the control level. In the fructose tolerance test, the increase in phosphomonoester and the decrease in P(i) and beta-ATP after i.v. fructose loading were apparent, but the degrees in these changes became smaller during the CCl4 intoxication. This wireless surface coil was useful for consecutive and non-invasive 31P NMR observations of the liver to follow chronically treated animal models over a period of several months.

Animals↗
PubMed1995

Platelet-derived growth factor B-chain comprises the major part of enhanced released mitogen from aortic endothelial cells of stroke-prone spontaneously hypertensive rats.

1. The present study was conducted to analyse the release and production of mitogen in cultured aortic endothelial cells of stroke-prone spontaneously hypertensive rats (SHRSP), for the further understanding of the role of arterial endothelial cells in the genesis of vascular lesions in hypertension. 2. The cultured aortic endothelial cells derived from SHRSP increased released mitogens were compared with those from control Wistar-Kyoto rats (WKY) with respect to cultured vascular medial smooth muscle cells and fibroblasts. 3. Biochemical analyses determined that the major part of mitogen released from aortic endothelial cells of both SHRSP and controls was the platelet-derived growth factor B-chain. 4. Further northern analyses revealed that the transcripts of PDGF B-chain were constitutively accumulated three- to four-fold in quiescent aortic endothelial cells from SHRSP, compared with those from WKY through passages 2 to 5. 5. However, the half-lives of the transcripts after actinomycin D treatment were 1.12 h (s.d. = 0.14, n = 4) and 1.28 h (s.d. = 0.08, n = 3), in SHRSP and in WKY, respectively, showing no significant difference. 6. These suggest that the increased accumulated transcripts of PDGF B-chain in SHRSP are due to an enhanced transcriptional rate. These enhanced release and production of PDGF-B chain in arterial endothelial cells, which may be induced under chronic hypertensive conditions, is suggested to contribute to the genesis of vascular lesion in hypertension, through the stimulation of vascular smooth muscle cell proliferation and hypertrophy.

Animals↗
PubMed1995

Pathogenesis of lacuna-like cyst formation and diffuse degeneration of the white matter in the brain of stroke-prone spontaneously hypertensive rats.

1. In an attempt to clarify the developmental mechanisms of lacuna and diffuse degeneration of the white matter in the brain in chronic hypertension, we investigated histologically the cerebral changes and histochemically, as well as biochemically, the lysosomal enzymes in the brain of stroke-prone spontaneously hypertensive rats (SHRSP). 2. The most prominent advanced lesions observed in SHRSP were cyst formation in the cortex and subcortical white matter, and diffuse degeneration of the white matter. On the other hand, the early cerebral changes were all related to blood-brain barrier dysfunction. The localization of cystic lesions and degeneration of the white matter corresponded very well with the extent of brain oedema demonstrated by immunostaining for leaked fibrinogen. All lysosomal enzyme activities in the adult SHRSP, both in the cortex and white matter, were higher than those in the controls. Histochemical investigation showed that SHRSP had an increased number of cells, reactive astrocytes and microglial cells, with positive reaction to lysosomal enzymes in the oedematous portion. 3. These findings suggest that chronic oedema due to blood-brain barrier dysfunction causes cystic changes as well as diffuse degeneration of the white matter, and that activated lysosomal enzymes in the reactive astrocytes and microglia play an important role in the development of such hypertensive lesions.

Animals↗
PubMed1995

Porphyromonas gingivalis fimbria-stimulated bone resorption in vitro is inhibited by a tyrosine kinase inhibitor.

Our previous study (Y. Kawata, S. Hanazawa, S. Amano, Y. Murakami, T. Matsumoto, K. Nishida, and S. Kitano, Infect. Immun. 62:3012-3016, 1994) showed that Porphyromonas gingivalis fimbriae stimulate bone resorption in vitro. Since it has recently been demonstrated that tyrosine kinase encoded by the c-src gene plays an important role in osteoclastic bone resorption, in the present study we examined the effect of a tyrosine kinase inhibitor on the fimbria-stimulated bone resorption. Genistein, a potent inhibitor of tyrosine kinase, markedly inhibited bone resorption stimulated by the fimbriae. Genistein also inhibited induction of several tyrosine-phosphorylated proteins in the fimbria-treated calvarial bone cells from mouse embryos.

Animals↗
PubMed1995

Modality dependency of familiarity ratings of Japanese words.

Familiarity ratings for a large number of aurally and visually presented Japanese words wer measured for 11 subjects, in order to investigate the modality dependency of familiarity. The correlation coefficient between auditory and visual ratings was .808, which is lower than that observed for English words, suggesting that a substantial portion of the mental lexicon is modality dependent. It was shown that the modality dependency is greater for low-familiarity words than it is for medium- or high-familiarity words. This difference between the low- and the medium- or high-familiarity words has a relationship to orthography. That is, the dependency is larger in words consisting only of kanji, which may have multiple pronunciations and usually represent meaning, than it is in words consisting only of hiragana or katakana, which have a single pronunciation and usually do not represent meaning. These results indicate that the idiosyncratic characteristics of Japanese orthography contribute to the modality dependency.

Adolescent↗
PubMed1995

[Effects of blowing or aspiration on ablation rate by excimer laser].

Accurate calibration of ablation rate by excimer laser prerequisite for precise photorefractive keratectomy (PRK). When a polymethylmethacrylate (PMMA) plate is ablated by excimer laser, debris is generated, which may affect homogeneity of the laser beam and energy density, and change the ablation rate. In order to clarify the effects of the debris on the ablation rate, we studied the changes in the ablation rate when the debris was removed by blowing or aspirating over the ablation area during PRK.PMMA plates were ablated using a scanning excimer laser system (EC-5000, NIDEK, Japan) in PRK mode under the following conditions: (1) with air blowing over the ablation area, (2) with aspiration of the debris, and (3) without treatment. The ablation rates were determined by measuring the refractive power of PMMA plates with a lens meter. The ablated surface was observed by scanning electron microscope (SEM). The ablation rate with blowing was the highest among the three conditions, that with aspiration was the second, and that without treatment was the lowest. The ablation rates with blowing showed no significant change when the ablation rates were changed. However, the ablation rates with aspiration or without treatment decreased as the pulse rate increased. The surface ablated during blowing was the smoothest in SEM photographs. We concluded that calibration of the ablation rate using PMMA plates must be done with appropriate air blowing.

Calibration↗
PubMed1994

Proliferative effects of humoral factors derived from neuroblastoma cells on cultured astrocytes.

The proliferative effects of humoral factors released from N18-RE105 neuroblastoma (NRE) cells on cultured astrocytes were assessed in separate co-culture and conditioned medium studies. In both experimental conditions, the humoral factors derived from neuroblastoma cells had growth-promoting effects on C6 glioma cells of astroglial lineage, but not on primary cultured astrocytes from new-born rat cerebral cortex. It is assumed that neuron-derived humoral factors include astroglial growth factors and that differences in responsiveness between two kinds of cells are probably related to the stages of astroglial maturation processes.

Animals↗
PubMed1994

A differential cloning procedure of complex genomic DNA fragments.

We have developed a differential cloning procedure designed for cloning of anonymous restriction DNA fragments whose molecular sizes differ between two genomic DNA preparations from higher organisms. The procedure, which was extensively revised from the original one, consists of several steps as summarized below. (i) Digestion of two DNA preparations (target and reference DNA) with the same restriction enzyme (4 base cutter). (ii) Biotinylation of target DNA and conversion of reference DNA to nonamplifiable form by terminal dephosphorylation. (iii) Electrophoresis of the two DNA preparations through a synthetic gel with a large excess of reference DNA as a competitor. (iv) In-gel alkaline dissociation of DNA, followed by reassociation (in-gel competitive reassociation). (v) Elution of DNA from the gel and PCR after adapter ligation and adsorption of DNA onto streptavidin-coated matrix. By repeating these steps, we attained substantial enrichment (approximately 10,000-fold) of DNA fragments which were originally present at one copy or less per complex mammalian genome. The details of the procedure and its unique characteristics in cloning of altered genomic DNA fragments, particularly from mammalian genome, are discussed.

Adenine Phosphoribosyltransferase↗
PubMed1994

Humoral factors derived from glial cells protect cultured neuroblastoma cells against glutamate toxicity.

The protective effects of glial cells against glutamate cytotoxicity on neuronal cells were studied using clonal neuroblastoma cells and two types of glial cells. Neuronal cells treated with glia-conditioned medium became able to tolerate glutamate toxicity. It is suggested that the preparatory processes against glutamate toxicity might be developed in neurons by the humoral factor(s) released from glial cells.

Animals↗
PubMed1994

alpha-Tocopherol protects against radical-induced injury in cultured neurons.

The effect of alpha-tocopherol on neurons in protecting against radical-induced injuries caused by cumene hydroperoxide was assessed using a culture system. Structural and biochemical deteriorations in both clonal neuroblastoma cells and primary cultured neurons were induced by cumene hydroperoxide. These deteriorative changes were prevented prevented by pretreatment of alpha-tocopherol. Since simultaneous supplementation of alpha-tocopherol and cumene hydroperoxide had limited protective effects, prophylactic administration of alpha-tocopherol for risk patients with brain diseases concerned with damages induced by free radical is recommended to hamper the progression of neuronal impairment after attacks.

Animals↗
PubMed1994

Specular microscopic evaluation of the corneal epithelium after excimer laser photorefractive keratectomy.

Nineteen eyes underwent photorefractive keratectomy to correct myopia. Using the specular microscope, we observed the central corneal epithelium of each eye preoperatively and at one, three, and six months after surgery. A normal epithelial pattern was observed in 18 eyes (94.7%) at one and three months and in 19 eyes (100%) at six months after surgery. There was no statistically significant difference in the pre- and postoperative mean cell area and corresponding coefficient of variation. These results suggest that the destruction of Bowman's layer produced by photorefractive keratectomy does not affect the morphologic characteristics of the most superficial layer of the corneal epithelium.

Adult↗
PubMed1994

Phorbol myristate acetate stimulates osteoclast formation in 1 alpha,25-dihydroxyvitamin D3-primed mouse embryonic calvarial cells by a prostaglandin-dependent mechanism.

Our previous study provided a novel assay system utilizing devitalized bone slices for study of the differentiation of osteoclast progenitors into preosteoclasts and mature osteoclasts among calvarial cells of mouse embryos. Using this assay system, we examined the effect of phorbol myristate acetate (PMA) on osteoclast formation as assessed by the appearance of tartrate-resistant acid phosphatase (TRAP)-positive cells and bone resorption lacunae. PMA alone was directly unable to induce the appearance of TRAP-positive cells and bone resorption lacunae of calvarial bone cells of mouse embryos. However, PMA markedly stimulated increases in the number of TRAP-positive cells and area of the resorption lacunae of the calvarial cells when the bone cells were primed by 1 alpha,25-(OH)2D3. This stimulatory effect of PMA was dose dependent. H-7, having relatively high affinity for protein kinase C, strongly inhibited in a dose-dependent fashion the stimulatory effect of PMA on the bone resorption of the hormone-primed calvarial cells. We also examined the involvement of prostaglandin in this stimulatory effect of PMA. Indomethacin, a cyclooxygenase inhibitor, markedly abolished the stimulatory effect of PMA on the bone resorption of the calvarial cells. PMA stimulated prostaglandin E2 (PGE2) production by the calvarial cells primed with 1 alpha,25-(OH)2D3 in a dose-dependent fashion. However, the PMA stimulation of the PGE2 production was significantly inhibited by H-7 and also by indomethacin. Furthermore, we observed that the addition of PGE2 to the calvarial cells primed with 1 alpha,25-(OH)2D3 for 1 or 3 days resulted in an increased number of TRAP-positive cells and increased bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Topographical evaluation of centration of excimer laser myopic photorefractive keratectomy.

We evaluated the centration of excimer laser myopic photorefractive keratectomy by analyzing the corneal topography in 60 eyes of 37 patients. Computer-assisted analysis of corneal topography was performed preoperatively and one week postoperatively. The distance and the direction from the center of the entrance pupil to the center of the ablation was calculated using a personal computer. Downward displacement of the ablation relative to the center of the entrance pupil was observed in 51 eyes (85%). The mean distance of the center of the ablation from the center of the entrance pupil was 0.51 +/- 0.31 mm (range 0.06 mm to 1.64 mm). To achieve more precise centration, we recommend applying an eye-movement tracking system to photorefractive keratectomy.

Adolescent↗
PubMed1994

Porphyromonas gingivalis fimbriae stimulate bone resorption in vitro.

Our previous study demonstrated that Porphyromonas gingivalis fimbriae induce the expression of interleukin-1, a potent bone-resorbing cytokine, in macrophages. This demonstration suggested to use the possibility that the fimbriae may stimulate bone resorption via the generation of an inflammatory cytokine(s). The present study was performed to test this suggestion. The bone-resorbing activity was evaluated by measuring the area of resorption lacunae on bone slices incubated with calvarial bone cells taken from 14-day-old mouse embryos. Fimbriae at 0.5 micrograms of protein per ml stimulated the bone-resorbing activity significantly, and the effect was dose and treatment time dependent. Since it is well known that interleukin-1 and granulocyte macrophage colony-stimulating factor induce differentiation of osteoclast lineage cells, we examined the involvement of these cytokines in fimbria-stimulated bone resorption. Fimbria-stimulated bone resorption was abolished significantly by antisera against both cytokines. We observed by Northern (RNA) blot assay that both cytokine genes were markedly expressed in the fimbria-treated calvarial bone cells. Our present data demonstrate that P. gingivalis fimbriae stimulate bone resorption in vitro.

Animals↗
PubMed1994

[Evaluation of physical exercise and fatigue sensation by CFSI (Cumulative Fatigue Symptoms Index)].

Cumulative Fatigue Symptoms Index (CFSI) is used for workers' subjective assessment of feeling of fatigue and of symptoms. Until now, this index has been used in the analysis of members of the same occupation. The purpose of this study is to examine fatigue symptoms in workers and to assess by CFSI the effect of regular physical exercise. Study participants were an exercise group (n = 67) and a non-exercise group (n = 115) of older workers, aged from 30 to 69 years. The CFSI questionnaire was distributed to all participants and the former group (exercise) answered two descriptive questions concerning the aim and subjective effects of physical exercise. As a result, it was found that mental fatigue symptoms decreased in the exercise group even after considering the differences in managerial position, subjective senses on health and marital status which are related to degree of feelings of fatigue. Weakened vitality was significantly less in the exercise group than the non-exercise group. Therefore, we concluded that weakened vitality would be needed to be regarded on an assessment scale for effects caused by exercise. It has also been considered that we should investigate general fatigue in assessing physical fatigue relating to one's lifestyle.

Adult↗