Biomedical subjects

E Satoh

Publications and source records attributed to E Satoh.

At least 73 records · Page 4Linked to original sources

PubMed1997

Effects of feeding conditions on sensitivity to tubocurarine of nerve-muscle preparations from the mouse.

1. The effects of feeding conditions on the sensitivity to the effect of tubocurarine (dTc) in vitro were compared among various nerve-muscle preparations from mice. The mice were fed under conditions that restricted or compelled their movement for 64 days and controls were fed conventionally. 2. The sensitivity to the effect of dTc differed considerably among preparations. It was much higher in the sciatic nerve-extensor digitorum longus muscle (EDL), moderately higher in the sciatic nerve-soleus muscle (SOL) and lower in the phrenic nerve-diaphragm (DPH) in control mice. 3. The order of the sensitivity was not altered by either type of conditioning. Constant restriction of movement or compelled movement did not modify the sensitivity of DPH to the effect of dTc in vitro. 4. Compulsion facilitated the sensitivity in both SOL and EDL. Restriction selectively increased the sensitivity of EDL. Both types of conditioning selectively and significantly reduced twitch development in EDL. 5. These results indicate that the sensitivity to dTc of neuromuscular transmission reflects constant states of motor activity.

Animals↗

PubMed1997

Effect of irradiation on transforming growth factor-beta secretion by malignant glioma cells.

Glioblastoma cells secrete transforming growth factor-beta (TGF-beta), which has a variety of immunosuppressive properties. We investigated the effect of irradiation TGF-beta secretion by malignant glioma cells. Three malignant glioma cell lines (T98G, A172, KG-1-C) were cultured and irradiated using 10 and 50 Gy Linac radiation. After further culture for 36 hours in serum-free culture medium, the supernatants were collected. The TGF-beta activity in the culture supernatants was determined using a specific bioassay. The levels of the active form and total TGF-beta in the supernatants from irradiated malignant glioma cells decreased compared to those from un-irradiated cells. However, since irradiation inhibited the growth of tumor cells, the amount of TGF-beta secretion per cell in irradiated cells tended to increase after irradiation. These results suggest that malignant glioma cells can still secrete TGF-beta and activate latent TGF-beta even after large dose irradiation, despite the inhibition of tumor growth.

Animals↗

PubMed1997

The alpha beta T cell receptor clustering upon superantigen/MHC recognition.

Antigen recognition by T cells is the key event for the antigen specific immune responses to be triggered. This recognition is initiated by the binding of the T cell receptor (TCR) to antigen peptide/major histocompatibility complex (MHC) on the surface of the antigen presenting cells. TCR on most of the T cells is a heterodimer composed of alpha and beta chains which are associated with CD3 gamma delta epsilon as well as zeta chains, the signal transmission molecules. The dynamics of this TCR complex upon antigen/MHC recognition, however, has not been well understood. In this paper the authors analyse the configuration of TCR complex on T cells from a TCR beta chain gene transgenic mouse (TGM) strain. Unlike many other TGM strains reported, a considerable proportion of T cells from this TGM expresses both transgene-encoded (V beta 3) and endogenous TCR beta chains on their surface. By immunoprecipitation and immunoblotting analysis of T cells stimulated with a superantigen, staphylococcal enterotoxin B (SEB), the authors found that V beta 3 was coprecipitated with V beta 8, demonstrating the clustering of TCR alpha beta upon superantigen/MHC recognition.

Animals↗

PubMed1997

Morphological characteristics of Epstein-Barr virus-related early gastric carcinoma: a case-control study.

A strong association between Epstein-Barr virus (EBV) and gastric carcinoma has been demonstrated by the uniform presence of EBV in all carcinoma cells, episomal monoclonality, elevated antibodies, and a unique 'lace pattern' in the mucosa. The present study is concerned with morphological changes of intramucosal carcinoma and submucosal invasion, reactive lymphocytes, and with atrophy and intestinal metaplasia of the surrounding mucosa. Fifty-two EBV-positive early gastric carcinomas were matched by age, sex, and site of tumor with 103 EBV-negative carcinomas, all of which had previously been examined by serial cut-sections of the tumors and surrounding mucosa. Epstein-Barr virus involvement was strongly associated with lace pattern morphology as demonstrated previously, and with lymphocytic infiltration in and around the tumor nests in the mucosa. The infiltrating lymphocytes in the tumor nests were mainly composed of CD8+ T lymphocytes. Lymphoepithelioma (LE)-like carcinoma, was observed in the submucosal portions of 13 of 31 EBV-positive cases with such invasions, including 12 of 29 with lace pattern morphology in the mucosa. The majority of the surrounding gastric mucosa showed moderate to severe atrophy with marked depletion of parietal cells, complete-type intestinal metaplasia in EBV-positive cases, and Helicobacter pylori (H. pylori) infection for both EBV-positive and EBV-negative cases. It is suggested that EBV infection may occur in the atrophic gastric epithelial cells associated with intestinal metaplasia and H. pylori infection, leading to the development of carcinoma. Such cancers show lace pattern and marked lymphocytic reaction in the mucosa, with some tendency for histological change and lymphocytic reaction during the invasive process without lymph node metastasis.

Aged↗

PubMed1997

Application of the extracellular alpha-amylase gene from Streptococcus bovis 148 to construction of a secretion vector for yogurt starter strains.

Streptococcus thermophilus ATCC 19258, Lactobacillus delbrueckii subsp. bulgaricus T-11, and Lactococcus lactis subsp. lactis IL1403 were transformed with the alpha-amylase gene (amyA) from Streptococcus bovis 148 by using a wide host-range vector, and all the transformants secreted the alpha-amylase successfully. Since the promoter and the secretion signal of the amyA gene were functional in these strains, we constructed a secretion vector using the expression elements of amyA. Trials to secrete foreign enzymes in yogurt starter strains were performed using this novel secretion vector.

Genetic Vectors↗

PubMed1997

Purification, characterization, and nucleotide sequence of an intracellular maltotriose-producing alpha-amylase from Streptococcus bovis 148.

An intracellular alpha-amylase from Streptococcus bovis 148 was purified and characterized. The enzyme was induced by maltose and soluble starch and produced about 80% maltotriose from soluble starch. Maltopentaose was hydrolyzed to maltotriose and maltose and maltohexaose was hydrolyzed mainly to maltotriose by the enzyme. Maltotetraose, maltotriose, and maltose were not hydrolyzed. This intracellular enzyme was considered to be a maltotriose-producing enzyme. The enzymatic characteristics and hydrolysis product from soluble starch were different from those of the extracellular raw-starch-hydrolyzing alpha-amylase of strain 148. The deduced amino acid sequence of the intracellular alpha-amylase was similar to the sequences of the mature forms of extracellular liquefying alpha-amylases from Bacillus strains, although the intracellular alpha-amylase did not contain a signal peptide. No homology between the intracellular and extracellular alpha-amylases of S. bovis 148 was observed.

Amino Acid Sequence↗

PubMed1997

[Proliferating character of inverted papilloma of the urinary bladder].

BACKGROUND: Inverted papilloma (IP) of the urinary bladder is generally considered to be a benign lesion by histological examination. In recent years, however, there have been several cases of IP simultaneously accompanied with transitional cell carcinoma (TCC), elsewhere in the bladder or combined as a single urothelial lesion. So we investigated proliferating character of IP by DNA ploidy analysis and immunohistostaining with proliferating cell nuclear antigen (PCNA). METHODS: Six cases of IP of the urinary bladder were analyzed and 12 cases of TCC of G1 and G3 grade were included in this study as a control. As DNA ploidy analysis, all specimens were feulgen stained using CAS DNA staining kit and examined by image cytometry (CAS 200R system). For the PCNA immunohistochemistry, all specimens were stained with anti-PCNA monoclonal antibody (Novocastra Lab.: PC10) according to ABC (avidin-biotin-complex) standard method. We determined that the DNA Index of the case under 1.20 was diploid and the others was aneuploid. PCNA staining were determined by only one pathologist as follows: negative (-) and positive (+), (2+) and (3+). RESULTS: As DNA ploidy, 5 of 6 cases of TCC G3 group as a control were aneuploid. But in spite of all cases of TCC G1 group were diploid, among IP cases, only 1 out of 6 was aneuploid. As PCNA staining, 2 of 6 in TCC G1 group and 5 of 6 in G3 group were positive. And it was noted examination was positive. CONCLUSION: There have been no recurrence since transurethral resection in all IP in the study including the case recognized as aneuploid and positive for PCNA staining. But the present results suggest that among IPs, considered generally as a benign tumor, the case which has high proliferating character exists.

Adult↗

PubMed1996

Dependence on temperature of the effect of dinitrophenol on the release of transmitter quanta at neuromuscular junctions in the mouse diaphragm.

1. The frequencies (F, s-1) of miniature endplate potentials and the quantal content (m) of endplate potentials were measured intracellularly and simultaneously at mouse diaphragm endplates in a bathing solution that contained 0.6 mM Ca2+ ions and 5 mM Mg2+ ions. 2. Twin pulses at 4 ms intervals gave the quantal contents of the first (m1) and second (m2) responses. The ratio of m2/m1 was taken as an indicator of the temporal facilitation of the release of transmitter. 3. Dinitrophenol (DNP, 10 microM) increased the values of F and m at 36 degrees C. This effect did not depend on extracellular Ca2+ ions. 4. The potentiating effect of DNP disappeared at 24 degrees C but the value of m2/m1 remained constant. 5. These results suggest that the effect of DNP is modifiable by temperature which can affect systems that control the intracellular metabolism of Ca2+ ions.

Animals↗

PubMed1996

Modulation of transforming growth factor-beta secretion from malignant glioma cells by interleukin-1 beta.

Malignant glioma cells secrete transforming growth factor-beta (TGF-beta) which has potent immunosuppressive properties. We investigated the effect of interleukin-1 beta (IL-1 beta) on TGF-beta secretion from malignant glioma cells in vitro. T98G glioblastoma cells were treated with various doses of IL-1 beta and the TGF-beta activity in the supernatant was determined using a specific bioassay. Six other human malignant glioma cell lines were also treated with 1000 U/ml of IL-1 beta, and the TGF-beta activity in the supernatants was determined. The effect of IL-1 beta on the growth of tumor cells was also assessed by a bioassay using crystal violet which reflects the actual cell number in the plate wells. IL-1 beta treatment resulted in inhibition of TGF-beta secretion in two malignant glioma cell lines. TGF-beta secretion from T98G cells was suppressed by IL-1 beta in a dose-related manner. However, IL-1 beta treatment resulted in an obvious increase (> 20%) of TGF-beta secretion in two tumor lines, and a slight increase (< 20%) in three tumor lines. IL-1 beta did not affect the growth of four malignant glioma cell lines, and only slightly affected the growth of the other three cell lines. IL-1 beta modulates TGF-beta secretion from malignant glioma cells, but not in a consistent way.

Cell Division↗

PubMed1996

Transforming growth factor-beta inhibits interferon-gamma secretion by lymphokine-activated killer cells stimulated with tumor cells.

The effect of transforming growth factor-beta (TGF-beta) secreted by glioblastoma (T98G) cells on the secretion of interferon-gamma (IFN-gamma) by lymphokine-activated killer (LAK) cells stimulated with tumor cells was investigated in cocultures of LAK and Daudi cells supplemented with T98G culture supernatant, T98G culture supernatant preincubated with anti-TGF-beta 1 and anti-TGF-beta 2 neutralizing antibodies, anti-TGF-beta 1 and anti-TGF-beta 2 antibodies, or natural human TGF-beta 1 or recombinant human TGF-beta 2. LAK cells were incubated with anti-TGF-beta 1 and anti-TGF-beta 2 antibodies, and with T98G cells of which the supernatant contained both active and latent forms of TGF-beta 1 and TGF-beta 2, with or without neutralizing antibodies. Addition of the supernatant from T98G cells to LAK/Daudi culture caused inhibition of IFN-gamma secretion by LAK cells. The inhibition was abolished by pretreatment of the supernatants with anti-TGF-beta antibodies. Addition of TGF-beta 1 and TGF-beta 2 to the LAK/Daudi culture inhibited IFN-gamma secretion by LAK cells in a dose-dependent manner. Addition of anti-TGF-beta antibodies to the LAK culture resulted in increased IFN-gamma secretion. T98G cells failed to stimulate LAK cells to secrete more IFN-gamma. Addition of anti-TGF-beta antibodies to the LAK-T98G culture resulted in increased IFN-gamma secretion by LAK cells. These results suggest that most malignant glioma cells which secrete high levels of TGF-beta can inhibit IFN-gamma secretion by LAK cells even after tumor cell stimulation.

Brain Neoplasms↗

PubMed1995

Secretion of transforming growth factor-beta 1 and -beta 2 by malignant glioma cells.

The secretion of transforming growth factor-beta (TGF-beta), a growth inhibitory factor with immunosuppressive properties, was investigated in one glioblastoma cell line and seven surgically resected malignant glioma cells. Cultured cells from surgically resected tumors were examined immunohistochemically for glial fibrillary acidic protein (GFAP) and S-100 protein. The levels of TGF-beta 1 and TGF-beta 2 in culture supernatants from malignant glioma cells were determined by a specific bioassay using anti-TGF-beta 1 and anti-TGF-beta 2 antibodies. Two glioblastoma cell lines were cultured in the presence of TGF-beta 1 or TGF-beta 2 to assess the effect of TGF-beta on the growth of glioblastoma cells. Cultured cells from surgically resected tumors were positive for both GFAP and S-100 protein. Both active and latent forms of TGF-beta 1 and TGF-beta 2 were detected in the culture supernatants from malignant gliomas, except in one patient with anaplastic astrocytoma which secreted only latent forms of TGF-beta 1 and TGF-beta 2. There was no statistical difference in the levels of TGF-beta 1 and TGF-beta 2 in glioblastomas and anaplastic astrocytomas. Neither TGF-beta 1 nor TGF-beta 2 affected the growth of glioblastoma cells. These findings suggest that most malignant glioma cells secrete both TGF-beta 1 and TGF-beta 2, can convert TGF-beta from a latent to active form, and may suppress cytokine secretion by activated lymphocytes in vivo as well as in vitro.

Astrocytoma↗

PubMed1994

Studies of the active-site lysyl residue of thermostable aspartate aminotransferase: combination of site-directed mutagenesis and chemical modification.

The gene technological substitution of the cysteinyl residue for the pyridoxal 5'-phosphate-binding lysyl residue (K239) of thermostable aspartate aminotransferase of Bacillus sp. YM-2 led to loss of the activity of the enzyme, which inherently contains no cysteinyl residues. The cysteinyl residue of the mutant enzyme was modified to lysine sulfur analog residues, S-(beta-aminoethyl)cysteine (SAEC), S-(beta-aminopropyl)cysteine (SAPC), and S-(beta-aminoethylthio)cysteine (SATC) with 2-bromoethylamine, 3-bromopropylamine, and 2-mercaptoethylamine, respectively. The modified mutant enzymes showed absorbance at 379 (K239SAEC), 400 (K239SAPC), and 365 nm (K239SATC), whereas the spectrum of the wild-type enzyme exhibited an absorption maximum at 360 nm derived from the internal Schiff base at pH 8.0. The absorption of the modified mutant enzymes at these wavelengths disappeared on reduction with NaCNBH3. This suggests that omega-amino groups of the introduced lysine sulfur analog residue form an internal Schiff base with pyridoxal 5'-phosphate. The modified mutant enzymes showed kcat values of 19.6-0.065% of that of the wild-type enzyme in the overall reaction, and were 10(6)-10(8) times more active than the K239C mutant enzyme. These results suggest that omega-amino groups of the introduced residues of the modified mutant enzyme serve as a catalytic base, and catalysis of the enzyme was affected by the length of the functional side-chain.

Aspartate Aminotransferases↗

PubMed1994

Inhibition of tumor necrosis factor-alpha and -beta secretion by lymphokine activated killer cells by transforming growth factor-beta.

Transforming growth factor-beta (TGF-beta) has a variety of immunosuppressive properties. We investigated the effect of TGF-beta secreted by glioblastoma (T98G) cells on the secretion of tumor necrosis factor-alpha and -beta (TNFs) by lymphokine activated killer (LAK) cells stimulated with tumor cells. The supernatant from T98G cells was preincubated with anti-TGF-beta 1 and -beta 2 neutralizing antibodies or untreated, and added to a coculture of LAK and Daudi cells. The neutralizing antibodies were added to LAK/Daudi and LAK culture, and natural human TGF-beta 1 and recombinant human TGF-beta 2 were also added to the LAK/Daudi culture. LAK cells were also cultured with T98G cells, of which the supernatant contained both active and latent forms of TGF-beta 1 and TGF-beta 2, and the neutralizing antibodies were added to the coculture. TNFs activity in the supernatants from LAK/Daudi cultures was examined by a specific bioassay. Addition of the supernatant from T98G cells to LAK/Daudi culture resulted in the inhibition of TNFs secretion by LAK cells. The inhibition was abrogated by the pretreatment of the supernatants with the anti-TGF-beta antibodies. Addition of TGF-beta 1 and TGF-beta 2 to LAK/Daudi culture inhibited TNFs secretion by LAK cells in a dose-dependent manner. Addition of anti-TGF-beta antibodies to LAK culture resulted in an increase of TNFs secretion. These results suggest that, if tumor cells have the capacity to convert TGF-beta from a latent to an active form, the active TGF-beta suppresses TNFs secretion by LAK cells stimulated with the tumor cells, and that TGF-beta secreted and activated by glioblastoma cells suppresses the propagation of immune reaction by inhibiting TNFs secretion by activated lymphocytes adjacent to tumor cells.

Glioblastoma↗

PubMed1994

Improved bioassay for the detection of transforming growth factor-beta 1 and beta 2 in malignant gliomas.

Growth inhibition assays using radioisotope or dye are used to detect transforming growth factor-beta (TGF-beta). Here, we describe a modified bioassay using crystal violet for the quantitative detection of TGF-beta 1 and TGF-beta 2. The procedure is based on staining Mv1Lu mink lung epithelial cells with crystal violet, followed by measurement of the absorbance at 570 nm in individual wells of a 96-well microtiter plate. The number of Mv1Lu cells correlated with the eluted dye intensity. The sensitivity of the bioassay to recombinant TGF-beta 1 and TGF-beta 2 increased approximately twofold by using only 500 Mv1Lu cells in microtiter wells. The bioassay was used to measure TGF-beta activity in the culture supernatant from glioblastoma cells. Culture supernatants were untreated or acid-activated to quantify the active or total TGF-beta, and neutralized with anti-TGF-beta 1 and/or anti-TGF-beta 2 antibody to measure the activity. Both TGF-beta 1 and TGF-beta 2 were detected in the untreated and acid-activated supernatants, and the amounts were calculated by extrapolating from the known recombinant TGF-beta 1 or TGF-beta 2 dilution curve. Our results show that the modified bioassay using crystal violet can measure the levels of TGF-beta 1 and TGF-beta 2 in culture supernatants from malignant glioma cells.

Biological Assay↗

PubMed1993

The effect of a reduction in temperature on the quantal release of transmitter at the mouse neuromuscular junction.

1. The effects of a reduction in temperature were examined on evoked and spontaneous release of transmitter quanta and on presynaptic negative signals, blocked by Cd2+, measured externally at neuromuscular junctions in mouse diaphragm muscles in low-Ca2+, high-Mg2+ Krebs-Ringer solutions. 2. The evoked release was enhanced with lowering of the temperature, whereas the extent of spontaneous release was reduced. Cooperativity of Ca2+ in the evoked release was slightly reduced by lowering the temperature. 3. The presynaptic negative signals increased in duration with lowering of the temperature. 4. These results support the hypothesis that the effect of a reduction in temperature reflects the improved efficacy of the calcium-mediated mechanism of transmitter release, manifested as a prolongation of the inflow of Ca2+. The process involved in the evoked release is probably attributable to an almost passive mechanism.

Animals↗

PubMed1993

Factors influencing the twin-pulse facilitation of the release of transmitter at the mouse neuromuscular junction.

1. The effects of several conditions and agents on the twin-pulse facilitation of the release of transmitter at the mouse neuromuscular junction in low-Ca2+ high-Mg2+ bathing solutions were examined. 2. Twin-pulses gave two endplate potential (epps) with first (m2) and second (m2) quantal contents. The ratio of m2/m1 was taken as a measure of the degree of facilitation. 3. The mean value of this ratio was > 1. Individual ratios fluctuated widely at junctions with smaller values of m1 but were focused around 1 at junctions with larger values of m1. Thus, some populations of junctions with smaller values of m1 contributed to an increment in the mean ratio. 4. The mean ratio was virtually constant irrespective of changes in the spontaneous and evoked release of transmitter at temperatures between 20 and 36 degrees C and at external concentrations of Ca2+ from 0.4 to 0.8 mM. 5. 4-Aminopyridine(4-AP) slightly but significantly increased this ratio with increases in m1 and m2 at temperatures of 24 and 36 degrees C. Ouabain slightly but significantly reduced the ratio, with increases in m1 and m2. The steadiness of the ratio was maintained in the presence of caffeine, high K+, neomycin or omega-conotoxin irrespective of changes in m1 and m2, except in the case of omega-conotoxin. 6. Spontaneous output at 36 degrees C increased in the presence of 4-aminopyridine, ouabain, caffeine, high K+ or neomycin. 7. These results indicate that maintenance of a stable value of the ratio of m2 to m1 is a dominant feature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

The affinity of betaxolol, a beta 1-adrenoceptor-selective blocking agent, for beta-adrenoceptors in the bovine trachea and heart.

1. The specificity of betaxolol, a beta-adrenoceptor antagonist, for beta 1- and beta 2-adrenoceptors was compared with that of other beta-antagonists, atenolol, ICI-118551, butoxamine and (+/-)-propranolol, in the bovine trachea and heart by competitive interaction with [3H]-CGP12177 as a radioligand. 2. The radioligand Kd values were 0.75 +/- 0.12 and 1.60 +/- 0.11 nM in the trachea and heart, respectively, and the Bmax values were 34.00 +/- 4.41 and 21.54 +/- 2.94 fmol mg-1 protein, respectively. 3. Using ICI-118551, we determined the ratio of beta 1:beta 2-adrenoceptors in the trachea and heart to be approximately 29:71 and 56:44, respectively. 4. In the trachea, a beta 2-predominant tissue, betaxolol and atenolol were more selective for beta 1-adrenoceptor binding sites than beta 2-adrenoceptor binding sites, whereas ICI-118551 and butoxamine were more selective for beta 2-adrenoceptor binding sites. 5. The beta 1-selectivity of betaxolol was 2.2 and 2.7 fold higher than that of atenolol in the bovine trachea and heart. These findings suggest that betaxolol may be useful in the treatment of hypertension, cardiac arrhythmia and angina pectoris.

Animals↗

PubMed1993

Molecular cloning and expression of two alpha-amylase genes from Streptococcus bovis 148 in Escherichia coli.

The alpha-amylase genes of Streptococcus bovis 148 were cloned in Escherichia coli MC1061, using pBR322. The recombinant plasmids were classified into two groups on the basis of their restriction maps. Southern blot analysis did not show homology between the two types of alpha-amylase genes, and the two alpha-amylase genes existed on the chromosomal DNA of S. bovis 148. The enzymatic properties and N-terminal amino acid sequences of the two purified enzymes produced by the cloned E. coli strains were quite different from each other. Particularly, one alpha-amylase (Amy I) was adsorbed on raw corn starch and hydrolyzed raw corn starch, and another (Amy II) was not adsorbed on raw corn starch and did not hydrolyze raw corn starch. Amy I was considered to be the same as the extracellular alpha-amylase of S. bovis 148 in raw starch absorbability, ability to hydrolyze raw corn starch, enzymatic characteristics, N-terminal amino acid sequence, and mode of action on soluble starch. Amy II showed a unique pattern of oligosaccharide production from soluble starch compared with the extracellular alpha-amylase of S. bovis 148. Amy II was suggested to be an intracellular alpha-amylase of S. bovis 148.

Amino Acid Sequence↗