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Biomedical subjects

S Amano

Publications and source records attributed to S Amano.

At least 163 records · Page 9Linked to original sources
PubMed1994

Novel antibiotics SF2738A, B and C, and their analogs produced by Streptomyces sp.

Three new antibiotics SF2738A, B and C, and their analogs were isolated from the culture broth of Streptomyces sp. The antibiotics are active against Gram-positive bacteria, Gram-negative bacteria and fungi, and exhibited cytotoxic activity against P388 murine leukemia cells with IC50 values of 0.08, 0.25 and 7.5 micrograms/ml, respectively. Their structures were determined by spectral analyses and chemical conversion. Especially, the structure of SF2738A was confirmed to be (E)-((4-methoxy-5-methylthio-2-(2-pyridyl)pyridin-6-yl)methylene)azan ol by X-ray crystallographic analysis.

Animals↗
PubMed1993

Corneal endothelial changes after excimer laser photorefractive keratectomy.

We used specular microscopy to investigate corneal endothelial changes after excimer laser photorefractive keratectomy. Twenty patients (26 eyes) underwent photorefractive keratectomy for the correction of myopia. The central cornea endothelium of each eye was observed preoperatively and one month postoperatively. Sixteen of the 26 eyes were examined by specular microscopy one year after photorefractive keratectomy. The corneal endothelial cell densities preoperatively, one month, and one year postoperatively were 3,221 +/- 216/mm2, 3,233 +/- 240/mm2, and 3,177 +/- 185/mm2 (mean +/- SD), respectively. The average coefficients of variation of mean cell area preoperatively and one month and one year postoperatively were 0.24 +/- 0.09, 0.23 +/- 0.05, and 0.22 +/- 0.05, respectively. There were no significant differences in mean cell density or the coefficients of variation of mean cell area among preoperative and one-month and one-year postoperative values. These results suggest that photorefractive keratectomy does not markedly affect the corneal endothelial cell density.

Adult↗
PubMed1993

Tumor necrosis factor-alpha induces expression of monocyte chemoattractant JE via fos and jun genes in clonal osteoblastic MC3T3-E1 cells.

The mechanism by which circulating monocytes are attracted to sites of bone remodeling is unknown. We now report that tumor necrosis factor-alpha (TNF-alpha), a potent osteotrophic cytokine, was stimulatory for expression of the monocyte chemoattractant JE gene in osteoblastic MC3T3-E1 cells. TNF-alpha stimulated this JE gene expression transcriptionally. The presence of JE gene product in conditioned medium of the cytokine-treated cells was evidenced by an immunoprecipitation assay with antiserum specific for JE/MCP-1. The stimulated JE gene expression was markedly inhibited by H-7, a potent inhibitor of protein kinase C. Phorbol 12-myristate 13-acetate induced the JE gene expression, and the cytokine-induced JE gene expression was down-regulated by the phorbol ester pretreatment. TNF-alpha induced expression of both early protooncogenes, c-fos and c-jun, in the cells. Antisense oligonucleotides to these oncogenes significantly inhibited the cytokine-induced monocyte chemotactic activity. Furthermore, curcumin, a specific inhibitor of c-jun/AP-1, markedly inhibited JE gene expression and monocyte chemotactic activity induced by the cytokine. These results suggest that TNF-alpha may contribute to the regulation of remodeling and inflammation of bone tissues through the JE gene product.

3T3 Cells↗
PubMed1993

Corneal epithelial changes after excimer laser photorefractive keratectomy.

We used the specular microscope to investigate corneal epithelial changes after excimer laser photorefractive keratectomy. Thirteen patients underwent photorefractive keratectomy on one eye to correct myopia. We observed the central corneal epithelium of each eye at postoperative periods from one to 15 months after photorefractive keratectomy. The fellow eye served as a control. In 11 eyes (85%) the central cornea showed normal epithelial patterns. Two eyes had an abnormal epithelial pattern that included elongated epithelial cells. There were no difference in the mean cell area or coefficient of variation of mean cell area between the treated eyes and the control eyes. These results suggest that permanent destruction of Bowman's membrane caused by photorefractive keratectomy does not affect the morphologic characteristics of the most superficial layer of the corneal epithelium in most eyes. However, the presence of abnormal epithelial cell patterns in two patients should be considered a risk factor for this procedure.

Adult↗
PubMed1993

IL-1 induces expression of monocyte chemoattractant JE in clonal mouse osteoblastic cell line MC3T3-E1.

Recent studies demonstrated that platelet-derived growth factor-inducible JE is an inflammatory cytokine that directs chemotaxis of monocytes, and is a homolog of monocyte chemoattractant protein-1, which is a human monocyte chemotactic factor. Migration and accumulation of monocyte lineage cells in bone tissue sites are very important for the recruitment of multinucleate osteoclasts, because the origin of osteoclasts is derived from monocyte lineage cells in hemopoietic cells. Because IL-1 is a potent regulator in bone remodeling, we examined whether IL-1 beta induces JE expression in a clonal mouse osteoblastic cell line, MC3T3-E1. Significant chemotactic activity for human monocytes was detected in conditioned medium of the cells at 6 h after initiation of IL-1 beta treatment, and the chemotactic activity increased in both a culture time- and dose-dependent manner. The peak of the chemotactic activity in the conditioned medium was observed in fractions corresponding to a m.w. of 26 kDa when the conditioned medium was fractionated by gel filtration. The chemotactic activity in the peak fraction was completely neutralized by antiserum specific for JE protein. And the JE gene product in the conditioned medium was detected as a microheterogeneous protein with a m.w. of 21 to 33 kDa by immunoprecipitation with the specific antiserum. IL-1 beta induced a maximal JE gene expression in the cells at 3 h after initiation of the cytokine treatment. This significant expression was observed when IL-1 beta was used at a concentration of 10 U/ml, and the expression was dose dependent. The run-on assay showed that the cytokine-induced JE gene expression increased at the transcriptional level. IL-1 beta and TNF-alpha acted synergistically to stimulate JE gene expression in the cells. Expression and product of the JE gene were also observed in an osteoblast-enriched cell population prepared from mouse calvariae. These results suggest the possibility that osteoblastic cells can participate in osteoclast recruitment via the JE gene product.

Animals↗
PubMed1993

Inherited amyloid polyneuropathy type IV (gelsolin variant) in a Japanese family.

We describe a Japanese family with familial amyloid polyneuropathy type IV. The family originates from central Japan, Nagano prefecture, and is unrelated to Finnish or other Caucasian populations. Of 42 members in three generations, 14 individuals (5 men, 9 women) are affected by corneal lattice dystrophy, cranial neuropathy, mild peripheral neuropathy, and skin changes. Polarizing microscopy and immunohistochemistry studies of skin biopsy samples demonstrated abundant amyloid deposits, which bound an antigelsolin monoclonal antibody. Direct sequence analysis of a DNA fragment spanning codon 187 of plasma gelsolin complementary DNA and restriction analysis using a modified polymerase chain reaction demonstrated a single base substitution, guanine to adenine, at nucleotide position 654, which is identical to the mutation in Finnish familial amyloid polyneuropathy type IV. This strongly suggests that the mutation causes the familial amyloid polyneuropathy type IV phenotype regardless of ethnic background.

Adult↗
PubMed1993

Hypoxic effects on glutamate uptake in cultured glial cells.

Hypoxic effects on glutamate uptake and ATP content in glial cells were investigated by using cultured C6 glioma cells. Mild regressive changes were found depending on the duration of the hypoxic insult, but necrosis or detachment of the cells from the substratum was rarely observed. Glutamate uptake was relatively well preserved after a short hypoxic insult, while a marked decrease in glutamate uptake was observed after hypoxia of long duration. The uptake of sucrose was reduced in a similar pattern to glutamate uptake. Hypoxic insult resulted in a significant reduction of the ATP content in glial cells. Therefore, the decrease in glutamate uptake by glial cells under hypoxia is likely to be due to ATP dependency, and not to the failure of a specific glutamate uptake system, but the failure of a general uptake of the glial cells owing to the energy-dependent membrane dysfunction by ATP depletion. These findings suggest that there are phased changes of astrocytic functions in a hypoxic condition, a preservative phase in the initial stages and then a dysfunctional phase in the later stages of hypoxia.

Adenosine Triphosphate↗
PubMed1993

Lattice corneal dystrophy type II with familial amyloid polyneuropathy type IV.

Lattice corneal dystrophy type II with familial amyloid polyneuropathy type IV (Finnish type, Meretoja's syndrome, FAP-IV) has not been reported in Japan to date. In this study we report on 7 cases in a Japanese family which we recently examined. The proband, a 64-year-old man, suffering from itching in his limbs, impaired lip movement and dysarthria, consulted the Department of Neurology, University of Tokyo. Neurological examinations revealed bilateral facial, glossopharyngeal, vagal and hypoglossal nerve palsies, and also impaired distal vibratory perception. Immunohistological and biochemical studies confirmed the diagnosis of FAP-IV. Ophthalmological examinations showed his vision was 1.2 with fine lattice corneal dystrophy in both eyes. The lattice dystrophy was randomly scattered with short glassy lines. Corneal sensation was normal and there was no evidence of recurrent corneal erosion. Six family members with similar lattice corneal dystrophies also were suspected to be affected neurologically by FAP-IV. The family pedigree suggested an autosomal dominant trait of inheritance.

Adult↗
PubMed1993

[Lattice corneal dystrophy type II with familial amyloid polyneuropathy type IV].

Lattice corneal dystrophy type II associated with familial amyloid polyneuropathy type IV (Finish type, FAP-IV) has not yet been reported in Japan. We report 7 cases in a Japanese family. The proband, a 64-year-old man, suffering from itching in his limbs, impaired lip movement, and dysarthria, consulted the Department of Neurology, University of Tokyo. Neurological examination revealed bilateral facial, glossopharyngeal, vagal, and hypoglossal nerve palsy, and impaired distal vibratory perception. His vision was 1.2 and he had fine lattice corneal dystrophy in both eyes. Short glassy lines were randomly scattered in the lattice dystrophy. Corneal sensation was normal and there was no evidence of recurrent corneal erosion. Immunohistological and biochemical studies confirmed the diagnosis of FAP-IV. Six siblings were neurologically suspected to be FAP-IV patients with similar lattice corneal dystrophy. The family pedigree suggested an autosomal dominant trait of inheritance.

Adult↗
PubMed1992

An assay system utilizing devitalized bone for assessment of differentiation of osteoclast progenitors.

The present study provides a novel assay system to examine the differentiation of osteoclast progenitors on devitalized bone slices. We used the population of bone cells liberated enzymatically from 14-day-old mouse embryonal calvariae as a source of osteoclast progenitors. The analysis of differentiation of osteoclast progenitors into preosteoclasts and mature osteoclasts was assessed in terms of the formation of TRAP-positive cells and pits or resorption lacunae, respectively, on devitalized bone slices. Osteoclasts having bone-resorbing activity appeared when the calvarial cell population was cultured in the presence of 1 alpha,25-(OH)2D3 on devitalized bone slices. The resorbing activity increased in a 1 alpha,25-(OH)2D3 dose-related manner. However, calcitonin, a potent inhibitor of differentiation and activation of osteoclast lineage cells, reduced the area of the resorption lacunae in a dose-dependent fashion. The bone-resorbing cells on the bone slices expressed an obvious ruffled border and clear zone, structures specific to mature osteoclasts. These results suggest that osteoclast progenitors in the mouse calvarial population examined differentiated into mature osteoclasts in the presence of 1 alpha,25-(OH)2D3 on devitalized bone slices. Further, using this assay system we assessed the effect of some other osteotropic factors on the differentiation of osteoclast progenitors to mature osteoclasts. IL-1, IL-6, and PTH increased the formation of TRAP-positive cells and pits and the area of resorption lacunae in a dose-dependent fashion. However, prostaglandin E2 was unable to induce the formation of resorption lacunae, although a significant appearance of TRAP-positive cells was observed at a concentration of 200 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1992

Porphyromonas gingivalis fimbriae induce expression of the neutrophil chemotactic factor KC gene of mouse peritoneal macrophages: role of protein kinase C.

To account for infiltration of the periodontal tissues by neutrophils, the present study was undertaken to examine whether Porphyromonas gingivalis fimbriae, important structures involved in attachment of the bacteria to periodontal tissues, induce gene expression of the neutrophil chemoattractant KC in macrophages. The fimbriae induced expression of the KC gene of mouse peritoneal macrophages in a dose-dependent fashion. The peak of KC gene expression was observed as early as 1 h after initiation of the treatment. However, the gene expression was short lived, with the expression decreasing gradually after 6 h. A nuclear transcriptional assay showed that the fimbriae regulated the KC gene expression at a posttranscriptional level. We observed that the fimbria-induced KC gene expression was not regulated by endogenous or exogenous prostaglandin. Furthermore, forskolin, a potent activator of adenyl cyclase, and dibutyryl cyclic AMP were incapable of inducing KC gene expression of the peritoneal macrophages. H-8 and HA 1004, inhibitors of cyclic nucleotide-dependent protein kinases, had little effect on the fimbria-induced KC gene expression. On the other hand, the fimbria-induced KC gene expression was inhibited markedly by treatment with H-7, a potent inhibitor of protein kinase C. We also observed that phorbol 12-myristate 13-acetate, a specific activator of protein kinase C, induced KC gene expression of peritoneal macrophages in a dose-dependent fashion. In addition, the fimbria-induced KC gene expression was suppressed in the peritoneal macrophages pretreated for 24 h with phorbol 12-myristate 13-acetate. These results suggest that the KC gene expression was mediated through activation of protein kinase C and not through that of cyclic nucleotide-dependent protein kinases. The present study indicates that P. gingivalis fimbriae can induce gene expression of the neutrophil chemotactic factor KC by macrophages via protein kinase C and suggests that this factor may be involved in infiltration of neutrophils into the periodontal tissues of adult periodontal patients.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

A new inhibitor of protein kinase C, RK-1409B (4'-demethylamino-4'-hydroxy-3'-epistaurosporine).

RK-1409B, a new inhibitor of protein kinase C, was isolated from the culture broth of Streptomyces platensis subsp. malvinus RK-1409. The structure was elucidated on the basis of spectroscopic analyses. RK-1409B inhibited protein kinase C in vitro and the morphological change of a human chronic leukemia cell line, K-562, induced by phorbol 12,13-dibutyrate with IC50 value of 0.4 microM.

Carbazoles↗
PubMed1992

Keratoepithelioplasty in rat: development of a model and histological study.

A model for keratoepithelioplasty (KEP) was developed using the Lewis rat, and histological studies were performed using this model. The entire corneal epithelium was removed mechanically and a 1.5-mm width of the conjunctiva including the limbus was excised. An oval corneal lamellar graft (3 x 1.5 mm) with an intact epithelium taken from another Lewis rat was transplanted on the denuded limbus. Biomicroscopic observations showed much less vascular invasion in the part of the cornea adjacent to the lenticule than in other parts of the cornea, and the cornea remained clear adjacent to the lenticule. Histologically, a few vessels were observed in the corneal stroma under the lenticule. Epithelial cells on the lenticule specimens showed histological characteristics of the corneal epithelium. These findings indicate that one of the functions of KEP is to block neovascularization in the newly developing corneal epithelium by transplanting the lenticule between the corneal epithelium and conjunctival vessels. The present study also confirmed that this model is useful in the research of the pathophysiological mechanism of KEP.

Animals↗
PubMed1992

[Histological study of a model of keratoepithelioplasty in the rat].

A model for keratoepithelioplasty (KEP) was developed using the Lewis rat, and histological studies were performed using the model. The entire corneal epithelium was removed using a spatula and a 1.5-mm-width of the conjunctiva including the limbus was excised. An oval corneal lamellar graft (3 x 1.5 mm) with an intact epithelium taken from another Lewis rat was transplanted on the denuded limbus. Biomicroscopic observation showed significantly less vascular invasion in the part of the cornea adjacent to the lenticule than in other part of cornea, and clear cornea was maintained in the cornea adjacent to the lenticule. Histologically only few vessels were recognized in the lenticule, and the epithelial cells on the lenticule showed histological characteristics of corneal epithelium. These results indicate that surgical function of KEP can be obtained because the lenticules keep distance between corneal epithelium and conjunctival vessels. And it is also confirmed that this model is useful in research on the pathophysiological mechanism of KEP.

Animals↗
PubMed1991

Bacteroides (Porphyromonas) gingivalis fimbriae activate mouse peritoneal macrophages and induce gene expression and production of interleukin-1.

The purpose of this study was to examine whether Bacteroides (Porphyromonas) gingivalis fimbriae, an important structure involved in attachment of the bacteria to periodontal tissues, activate macrophages and subsequently induce gene expression and production of interleukin-1 (IL-1) in the cells. The fimbriae increased glucose consumption and lysozyme activity in BALB/c macrophages, both criteria of macrophage activation of peritoneal macrophages, in a dose-dependent fashion. A marked increase in the mRNA level of the c-myc gene, an oncogene, in the cells was observed after a 1-h treatment with the fimbriae, and the level decreased rapidly after 3 h. The fimbriae (4 micrograms of protein per ml) markedly induced IL-1 alpha and IL-1 beta gene expression in the cells and IL-1 production. The expression of IL-1 alpha and IL-1 beta genes measured in terms of specific mRNA increased 1 h after the start of treatment and peaked at 6 h. Such increased expression of IL-1 beta was also observed in C3H/HeJ mice, a lipopolysaccharide low-responder strain. The fimbriae stimulated transcriptional activity of IL-1 beta in the cells, but not that of IL-1 alpha. We also observed that fimbriae-induced IL-1 gene expression was not regulated by endogenous prostaglandin triggered by the fimbriae. Therefore, these observations suggest that B. gingivalis fimbriae may be involved in the pathogenesis of adult periodontal disease via triggering of IL-1 production by monocytes/macrophages in periodontal diseases.

Animals↗
PubMed1990

Hypoxia prevents seizures and neuronal damages of the hippocampus induced by kainic acid in rats.

The effects of hypoxia on the epileptic seizures and neuronal damages induced by kainic acid were studied in rats using hypoxic chamber equipment. Rats treated with kainic acid and placed in atmospheric pressure showed typical limbic seizures and regressive neuronal changes in CA3 and CA4 of the hippocampus, while those kept in a hypoxic chamber with 8.5% O2 and 91.5% N2 showed moderate hypoxia and a slight decline of mean arterial blood pressure. In these hypoxic rats, seizures were completely prevented and there was remarkably less regressive neuronal injury of the hippocampus. Thus hypoxia has a rather ameliorative effect on the occurrence of seizures and excitotoxic neuronal injuries induced by kainic acid. The contribution of oxygen radicals and endogenous adenosine to preventing excitotoxic neuronal damages by kainic acid was discussed.

Animals↗
PubMed1990

Increased 5'-nucleotidase activity induced by dibutyryl cyclic AMP treatment of cultured glial cells.

In an attempt to clarify the relationship between ecto-5'-nucleotidase (5'-N) activity and cell differentiation of glial cells, dibutyryl cyclic AMP (dBcAMP), which induces cell differentiation, was administrated to cultured rat glioma cells in logarithmic and confluent phases of cultivation. To evaluate the cellular differentiation, cell morphology and the number of glial fibrillary acidic protein (GFAP) positive cells were examined. Treatment with 1 mM dBcAMP decreased cell proliferation and induced cell differentiation in both the logarithmic and the confluent phases. The number of GFAP-positive cells increased with cellular aging and this tendency was enhanced by dBcAMP administration. Ecto-5'-N activity was higher in dBcAMP treated cells than in non-treated cells in both the logarithmic and the confluent phases. These findings suggest that ecto-5'-N activity of C6 glioma cells is increased by dBcAMP actions and is accompanied by cell differentiation.

5'-Nucleotidase↗