Biomedical subjects

Koji Yamada

Publications and source records attributed to Koji Yamada.

At least 19 recordsLinked to original sources

PubMed2007

Effect of royal jelly on bisphenol A-induced proliferation of human breast cancer cells.

Royal jelly is known as a functional food containing many useful minerals. In this study, we found an anti-environmental estrogen activity of royal jelly. Bisphenol A (BPA) is an environmental estrogen that stimulates proliferation of human breast cancer MCF-7 cells. Royal jelly inhibited the growth-promoting effect of BPA on MCF-7 cells, even though it did not affect the proliferation of cells in the absence of BPA. In addition, this inhibiting effect of royal jelly was heat-stable.

Benzhydryl Compounds↗

PubMed2006

The involvement of the 67 kDa laminin receptor-mediated modulation of cytoskeleton in the degranulation inhibition induced by epigallocatechin-3-O-gallate.

Recently, we have reported that (-)-epigallocatechin-3-O-gallate (EGCG) acts as an inhibitor of degranulation. However, the inhibitory mechanism for degranulation is still poorly understood. Here we show that suppression of exocytosis-related myosin II regulatory light chain phosphorylation and alteration of actin remodeling are involved in the inhibitory effect of EGCG on the calcium ionophore-induced degranulation from human basophilic KU812 cells. Surface plasmon resonance assay also revealed that EGCG binds to the cell surface, and the disruption of lipid rafts resulted in reduction of EGCG's ability. We have previously identified the raft-associated 67kDa laminin receptor (67LR) as an EGCG receptor on the cell surface. Treatment of the cells with anti-67LR antibody or RNA interference-mediated downregulation of 67LR expression abolished the effects of EGCG. These findings suggest that EGCG-induced inhibition of the degranulation includes the primary binding of EGCG to the cell surface 67LR and subsequent modulation of cytoskeleton.

Basophils↗

PubMed2006

Mode of interaction of ganglioside Langmuir monolayer originated from echinoderms: three binary systems of ganglioside/DPPC, ganglioside/DMPE, and ganglioside/cholesterol.

The surface pressure (pi)-area (A), the surface potential (DeltaV)-A, and the dipole moment (mu( perpendicular))-A isotherms were obtained for monolayers made from a ganglioside originated from echinoderms [Diadema setosum ganglioside (DSG-1)], dipalmitoylphosphatidylcholine (DPPC), dimyristoylphosphatidylethanolamine (DMPE), cholesterol (Ch), and their combinations. Monolayers spread on several different substrates were investigated at the air/water interface by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM) and atomic force microscopy (AFM). Surface potentials (DeltaV) of pure components were analyzed using the three-layer model proposed by Demchak and Fort [R.J. Demchak, T. Fort, J. Colloid Interface Sci. 46 (1974) 191-202]. The new finding was that DSG-1 was stable and showed a liquid-expanded film and that its monolayer behavior of DeltaV was sensitive for the change of the NaCl concentration in the subphase. Moreover, the miscibility of DSG-1 and three major lipids in the two-component monolayers was examined by plotting the variation of the molecular area and the surface potential as a function of the DSG-1 molar fraction (X(DSG-1)), using the additivity rule. From the A-X(DSG-1) and DeltaV(m)-X(DSG-1) plots, partial molecular surface area (PMA) and apparent partial molecular surface potential (APSP) were determined at the discrete surface pressure. The PMA and APSP with the mole fraction were extensively discussed for the miscible system. The miscibility was also investigated from the two-dimensional phase diagrams. Furthermore, a regular surface mixture, for which the Joos equation was used for the analysis of the collapse pressure of two-component monolayers, allowed calculation of the interaction parameter (xi) and the interaction energy (-Deltavarepsilon) between them. The observations using fluorescence microscopy and AFM image also provide us the miscibility in the monolayer state.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2006

Dietary apigenin suppresses IgE and inflammatory cytokines production in C57BL/6N mice.

Flavonoids ubiquitously exist in plants, vegetables, fruits, and teas. We evaluated the effect of dietary apigenin, one of the well-known flavonoids, on the immune system in C57BL/6N mice. Mice were fed experimental diets containing apigenin for 2 weeks. After the experimental period, there was no significant difference in body and organ weights between the control and the apigenin group. The total immunoglobulin (Ig) E levels in mice fed apigenin were significantly suppressed, whereas levels of IgG, IgM, and IgA were not affected. We also examined the effect of the apigenin diet on cytokine expression in mice sera using a cytokine array. The production of regulated upon activation normal T cell expressed and secreted (RANTES) and soluble tumor necrosis factor receptor I (sTNFRI) in mice sera was down-regulated by the apigenin diet. These results suggest that a diet containing apigenin can reduce serum IgE and inflammatory cytokines such as RANTES and sTNFRI in mice.

Animals↗

PubMed2006

Fluorescence microscopic investigation on morphological changes of giant multilamellar vesicles induced by amphiphilic additives.

Adding an artificial bolaamphiphile to a dispersion of giant multilamellar vesicles (GMVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) induced a cup-shaped deformation in GMVs accompanied by partial extrusion of the inner vesicle; thereafter, the deformed vesicles returned to their original shape. On the other hand, when the artificial bolaamphiphile together with a surfactant was added to the vesicular dispersion, these deformation and reformation dynamics were transmitted from the outer membranes in GMVs to the inner membranes until an intact inner vesicle was extruded out of the outer membrane. The microscopic aspects of these processes were investigated using amphiphiles tagged with individual fluorophores.

Journal Article↗

PubMed2006

Constituents of Holothuroidea, 18. Isolation and structure of biologically active disialo- and trisialo-gangliosides from the sea cucumber Cucumaria echinata.

Three new disialo- and trisialo-gangliosides, CEG-6 (6), CEG-8 (8), and CEG-9 (9), were obtained, together with one known ganglioside, HLG-3 (7), from the lipid fraction of the chloroform/methanol extract of the sea cucumber Cucumaria echinata. The structures of the new gangliosides were determined on the basis of chemical and spectroscopic evidence to be 1-O-[alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->4)-(N-acetyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (6) and 1-O-[(N-glycolyl-D-neuraminosyl)-(2-->11)-(N-glycolyl-D-neuraminosyl)-(2-->4)-(N-acetyl-D-neuraminosyl)-(2-->6)-D-glucopyranosyl]-ceramide (8, 9). The ceramide moieties of each compound were composed of an homogeneous sphingosine or phytosphingosine base and heterogeneous 2-hydroxy or nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor.

Animals↗

PubMed2006

Constituents of Holothuroidea, 17. Isolation and structure of biologically active monosialo-gangliosides from the sea cucumber Cucumaria echinata.

Three new monosialo-gangliosides, CEG-3 (3), CEG-4 (4), and CEG-5 (5), were obtained, together with two known gangliosides, SJG-1 (1) and CG-1 (2), from the lipid fraction of the chloroform/methanol extract of the sea cucumber Cucumaria echinata. The structures of the new gangliosides were determined on the basis of chemical and spectroscopic evidence to be 1-O-[4-O-acetyl-alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (3) and 1-O-[alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (4, 5). The ceramide moieties of each compound were composed of heterogeneous sphingosine or phytosphingosine bases, and 2-hydroxy or nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor.

Animals↗

PubMed2006

Reduced expression of perchloric acid-soluble protein after partial hepatectomy in rats.

We examined the expression of perchloric acid-soluble protein (PSP) during liver regeneration after partial hepatectomy (PH) in rats. Liver regeneration was almost complete at 7-d after PH. Expression of PSP protein and mRNA decreased and then gradually increased during liver regeneration. An immunohistochemical study showed that PSP is distributed in cytosol and nuclei in normal liver, but localization in the nuclei was not be recognized in the regenerated liver.

Animals↗

PubMed2006

Effect of estrogens on the interferon-gamma producing cell population of mouse splenocytes.

We examined the effect of 17beta-estradiol (E2) on the cytokine production by mouse splenocytes. The production of interferon-gamma (IFN-gamma) was enhanced by E2 stimulation. E2 increased the number of cells expressing IFN-gamma and the IFN-gamma mRNA expression level in the cells. There were low- and high-level cells expressing IFN-gamma in the population. The natural killer (NK) cells and NKT cells were the low-level cells expressing IFN-gamma, and the number of these cells was increased by E2 stimulation. In addition, it was suggested that the enhancing effect of IFN-gamma production by E2 was mediated through estrogen receptor (ER) alpha, and ERbeta agonist stimulated IFN-gamma production. ERs are expressed on plasma membrane as well as in nucleus. The ligand specific to plasma membrane-associated ER (mER) enhanced the IFN-gamma production. In conclusion, our results indicated that E2 up-regulated the IFN-gamma production by mediating ERalpha, ERbeta and mERs.

Animals↗

PubMed2006

[Successful platelet recovery after the second eradication of Helicobacter pylori with metronidazole in two patients with chronic idiopathic thrombocytopenic purpura].

There are many reports on the efficacy of Helicobacter pylori (H. pylori) eradication therapy in patients with H. pylori-positive chronic idiopathic thrombocytopenic purpura (ITP). We administrated metronidazole (MNZ), amoxicillin (AMPC), and a proton-pump inhibitor (PPI) as the second eradication therapy for two patients who failed in the first eradication therapy consisting of PPI, AMPC, and clarithromycin (CAM). Successful eradication and the rapid recovery of platelet counts within one month were achieved in both patients. Recently, H. pylori eradication is considered as the first-line therapy for H. pylori-positive chronic ITP patients. In Japan, the PPI + AMPC + CAM regimen is recognized as the standard eradication therapy for H. pylori. However, the PPI + AMPC + MNZ regimen is also useful for eradication and should be tried as the re-treatment regimen after failure of the first-line CAM-containing regimen.

Aged↗

PubMed2005

Apoptosis induction by gamma-tocotrienol in human hepatoma Hep3B cells.

We evaluated the antitumor activity of tocotrienol (T3) on human hepatoma Hep3B cells. At first, we examined the effect of T3 on the proliferation of human hepatoma Hep3B cells and found that gamma-T3 inhibited cell proliferation at lower concentrations and shorter treatment times than alpha-T3. Then, we examined the effect of gamma-T3 apoptosis induction and found that gamma-T3 induced poly (ADP-ribose) polymerase (PARP) cleavage and stimulated a rise in caspase-3 activity. In addition, gamma-T3 stimulated a rise in caspase-8 and caspase-9 activities. We also found that gamma-T3-induced apoptotic cell death was accompanied by up-regulation of Bax and a rise in the fragments of Bid and caspase-8. These data indicate that gamma-T3 induced apoptosis in Hep3B cells and that caspase-8 and caspase-9 were involved in apoptosis induction. Moreover, these results suggest that Bax and Bid regulated apoptosis induction by gamma-T3.

Apoptosis↗

PubMed2005

Isoflavone genistein and daidzein up-regulate LPS-induced inducible nitric oxide synthase activity through estrogen receptor pathway in RAW264.7 cells.

Isoflavones, such as genistein and daidzein, are found in abundance in soybeans. These plant-derived substances have estrogenic activities and can bind to the estrogen receptors (ERs). In this study, we investigated that the effects of 17beta-estradiol (E2), genistein and daidzein on nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) activity in RAW264.7 cells. We found that these isoflavones significantly increased lipopolysaccharide-induced NO production and iNOS expression as much as E2 at physiological concentrations. Moreover, E2 and isoflavone enhanced the production of tumor necrosis factor-alpha that is one of the important cytokines regarding NO production. The enhancing effects of E2 and isoflavones on NO production were markedly inhibited by not only N(G)-nitro-L-arginine methyl ester (an inhibitor of NOS), but also ICI 182780 (ERs antagonist). Two types of ERs were identified as ERalpha and ERbeta. An ERalpha agonist could increase iNOS expression in RAW264.7 cells, while an ERbeta agonist could not. In conclusion, our results suggest E2, genistein and daidzein activate iNOS, and then up-regulate NO production. This enhancing effect is aroused through ERalpha pathway in RAW264.7 cells.

Animals↗

PubMed2005

A lipid raft-associated 67kDa laminin receptor mediates suppressive effect of epigallocatechin-3-O-gallate on FcepsilonRI expression.

(-)-Epigallocatechin-3-O-gallate (EGCG), a major green tea polyphenol, has previously exhibited a suppressive effect on the expression of the high-affinity IgE receptor (FcepsilonRI). This effect has been shown to be elicited by interaction with the plasma membrane microdomain lipid rafts. Recently, we have identified the 67 kDa laminin receptor (67LR) as a cell surface EGCG receptor that mediates an anti-cancer action. Here we show that the 67LR is highly associated with lipid rafts on human basophilic KU812 cells. Experiments using 67LR-enhanced and -reduced cells revealed that the EGCG's ability to downregulate FcepsilonRI expression correlated with the amount of 67LR. Thus, these results suggest that the lipid raft-associated 67LR plays an important role in mediating the FcepsilonRI-suppressive action of EGCG.

Catechin↗

PubMed2005

Dietary effect of pomegranate seed oil on immune function and lipid metabolism in mice.

OBJECTIVES: We evaluated the effects of dietary pomegranate seed oil (PSO), which contains high levels of punicic acid (9c, 11t, 13c-octadecatrienoic acid), on immune function and lipid metabolism in C57BL/6N mice. METHODS: Mice were fed experimental diets containing 0%, 0.12%, or 1.2% PSO for 3 wk. RESULTS: No significant differences were observed between growth patterns of the experimental groups. Splenocytes isolated from mice fed 0.12% or 1.2% PSO produced larger amounts of immunoglobulins G and M but not immunoglobulin A irrespective of stimulation with or without phorbol 12-myristate 13-acetate and the calcium ionophore A23187. Dietary PSO did not affect the percentages of B cells or CD4-positive or CD8-positive T cells in splenocytes. Levels of interleukin-4, interferon-gamma, and tumor necrosis factor-alpha production from splenocytes were comparable among all dietary groups. Analysis of serum lipid parameters showed significant increases in serum triacylglycerol and phospholipid levels but not in total cholesterol in the PSO groups. Serum, liver, epididymal, and perirenal adipose punicic acid levels were high with increases in dietary PSO level. However, punicic acid was not detected in splenocytes for any dietary group. Interestingly, 9c, 11t-conjugated linoleic acid level could be detected in serum, liver, and adipose tissues in mice fed the 0.12% or 1.2% PSO diet. CONCLUSIONS: These results suggest that PSO may enhance B-cell function in vivo.

Animals↗

PubMed2005

Trans10, cis12-conjugated linoleic acid induces mitochondria-related apoptosis and lysosomal destabilization in rat hepatoma cells.

Conjugated linoleic acid (CLA) is a powerful anti-carcinogenic fatty acid. Previously, we showed that 10trans 12cis (10t, 12c) CLA induced apoptotic cell death in rat hepatoma. Here, we demonstrated significant cytotoxic effects of 1 muM 10t, 12c-CLA, but not 9c, 11t-CLA, on dRLh-84 rat hepatoma cells. 9t, 11t and 9c, 11c-CLA also showed low levels of cytotoxic activity. 10t, 12c-CLA activated caspase-3, 9 followed by cytochrome c release from mitochondria into the cytosol. Inhibitors of caspase-3, 9 blocked the cytotoxicity of 10t, 12c-CLA. 10t, 12c-CLA also induced translocation of Bax protein into the mitochondrial membrane and cleavage of Bid protein. Lysosomal destabilization induced by 10t, 12c-CLA was observed by monitoring the re-localization of Acridine Orange and the leakage of beta-hexosaminidase from lysosomes. 10t, 12c-CLA directly degraded the isolated lysosomes from the rat liver. Our observations indicate that 10t, 12c-CLA induces mitochondria-related apoptosis accompanied by lysosomal destabilization in rat hepatoma cells.

Animals↗

PubMed2005

Nuclear transfer of perchloric acid-soluble protein by endoplasmic reticulum stressors.

Perchloric acid-soluble protein (PSP) is highly conserved during evolution from bacteria to mammals. Although PSP has been recognized as an inhibitor of translation and proliferation in vitro, its precise biological role has not yet been elucidated. Since we previously found similar distributions for PSP and the endoplasmic reticulum (ER) and Golgi complex, the intracellular distribution of PSP was analyzed in more detail. Immunofluorescence studies indicated that PSP co-localized with the ER and Golgi complex, since the distribution pattern of PSP was well matched to both of these organelles. An immunoelectron microscopic study revealed PSP was located not only in the cytosol but also on the surface of the outer ER membrane. Since PSP was present on the ER, we speculated that it may be associated with ER function. Therefore, we analyzed whether or not the ER stress response, which is one of the ER functions, affected PSP expression. The results showed that various ER stressors (thapsigargin, A23187, tunicamycin, brefeldin A, and cisplatin) provoked a dramatic change in the localization of PSP from outside of the nucleus to inside the nucleus within 3 h. Moreover, the ER stressors induced PSP expression. These results suggest that PSP is involved in the cellular response to ER stressors, and that the change in localization of PSP from the ER to the nucleus may be associated with ER stress responses.

Active Transport, Cell Nucleus↗

PubMed2005

Epigallocatechin-3-O-gallate disrupts stress fibers and the contractile ring by reducing myosin regulatory light chain phosphorylation mediated through the target molecule 67 kDa laminin receptor.

Epigallocatechin-3-O-gallate (EGCG), a major polyphenol of green tea, has been shown to inhibit the growth of various cancer cell lines. We show here that EGCG induced the disruption of stress fibers and decreased the phosphorylation of the myosin II regulatory light chain (MRLC) at Thr18/Ser19, which is necessary for both contractile ring formation and cell division. Indirect immunofluorescence analysis revealed that EGCG inhibited the concentration of both F-actin and the phosphorylated MRLC in the cleavage furrow at the equator of dividing cells. In addition, EGCG increased the percentages of cells in the G(2)/M phase and inhibited cell growth. Recently, we have demonstrated that the anticancer activity of EGCG is mediated by the metastasis-associated 67kDa laminin receptor (67LR). To explore whether the effect of EGCG is mediated by the 67LR, we transfected cells with short hairpin RNA (shRNA) expression vector to downregulate 67LR expression. When the 67LR was silenced, the suppressive effect of EGCG on the MRLC phosphorylation was significantly attenuated. These results suggest that EGCG inhibits the cell growth by reducing the MRLC phosphorylation and this effect is mediated by the 67LR.

Actins↗

PubMed2005

Isolation and physiochemical properties of protein-rich nematode mitochondrial ribosomes.

In the present study, mitochondrial ribosomes of the nematode Ascaris suum were isolated and their physiochemical properties were compared to ribosomes of Escherichia coli. The sedimentation coefficient and buoyant density of A. suum mitochondrial ribosomes were determined. The sedimentation coefficient of the intact monosome was about 55 S. The buoyant density of formaldehyde-fixed ribosomes in cesium chloride was 1.40 g/cm(3), which suggests that the nematode mitoribosomes have a much higher protein composition than other mitoribosomes. The diffusion coefficients obtained from dynamic light scattering measurements were (1.48 +/- 0.04) x 10(-)(7) cm(2) s(-)(1) for 55 S mitoribosomes and (1.74 +/- 0.04) x 10(-)(7) cm(2) s(-)(1) for the 70 S E. coli monosome. The diameter of mitoribosomes was measured by dynamic light-scattering analysis and electron microscopy. Though the nematode mitoribosome has a larger size than the bacterial ribosome, it does not differ significantly in size from mammalian mitoribosomes.

Animals↗