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101.
Atsushi Suzuki Jun Kotoyori Yutaka Oiso Osamu Kozawa 《Cell communication & adhesion》1993,1(2):113-118
Extracellular ATP dose dependently stimulated 45Ca2+ influx even in the presence of nifedipine, a Ca2+ antagonist that inhibits voltage-dependent Ca2+ channel, in osteoblast-like MC3T3-E1 cells. ATP stimulated arachidonic acid release and the synthesis of prostaglandin E2 (PGE2). However, the ATP-induced arachidonic acid release was significantly reduced by chelating extracellular Ca2+ with EGTA. On the other hand, ATP induced DNA synthesis of these cells in a dose-dependent manner in the range between 1μM and 1 mM. The pretreatment with indomethacin, a cyclooxygenase inhibitor, suppressed both ATP-induced PGE2 synthesis and DNA synthesis in these cells. The inhibitory effect by 50μM indomethacin on the DNA synthesis was reversed by adding 10μM PGE2. These results strongly suggest that extracellular ATP stimulates Ca2+ influx resulting in the release of arachidonic acid in osteoblast-like cells and that extracellular ATP-induced proliferative effect is mediated, at least in part, by ATP-stimulated PGE2 synthesis. 相似文献
102.
Haruhiko Tokuda Jun Kotoyori Atsushi Suzuki Yutaka Oiso Osamu Kozawa 《Journal of cellular biochemistry》1993,52(2):220-226
We investigated the effects of vitamin D3 on the signaling pathways by prostaglandin E2 (PGE2) in osteoblast-like MC3T3-E1 cells. The pretreatment with 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), an active form of vitamin D3, significantly inhibited cAMP accumulation induced by 10 μM PGE2 in a dose-dependent manner in the range between 1 pM and 1 nM. This effect of 1,25-(OH)2D3 was dependent on the time of pretreatment up to 8 h. 1,25-(OH)2D3 also inhibited the cAMP accumulation induced by NaF, a GTP-binding protein activator, or forskolin which directly activates adenylate cyclase. On the other hand, 1,25-(OH)2D3 significantly inhibited PGE2-induced IP3 formation in a dose-dependent manner between 10 pM and 1 nM. However, 1,25-(OH)2D3 had little effect on NaF-induced IP3 formation. The pretreatment with 24,25-dihydroxyvitamin D3, an inactive form of vitamin D3, affected neither cAMP accumulation nor IP3 formation induced by PGE2. These results strongly suggest that 1,25-(OH)2D3 modulates the signaling by PGE2 in osteoblast-like cells as follows: the inhibitory effect on the cAMP production is exerted at a point downstream from adenylate cyclase and the inhibitory effect on the phosphoinositide hydrolysis is exerted at the point between the PGE2 receptor and GTP-binding protein, probably Gi2. 相似文献
103.
104.
Ota Yoko; Ario Takeshi; Hayashi Koji; Nakagawa Tsuyoshi; Hattori Tsukaho; Maeshima Masayoshi; Asahi Tadashi 《Plant & cell physiology》1992,33(3):225-232
Catalases purified from endosperm glyoxysomes and non-specializedmicrobodies from hypocotyls of castor bean seedlings differedin their specific activity [90164 and 0.894.9kunits (mg protein)1, respectively] and in their constituentsubunits [two subunits of 54 and 56 kDa for the endosperm enzymeand only one of 56 kDa for the hypocotyl enzyme]. Immunoblotanalysis also showed that particulate fractions from the endospermsand from etiolated and green cotyledons contained two catalasesubunits of 54 and 56 kDa, whereas such fractions from the hypocotylsand roots contained only the 56-kDa subunit. Leaf peroxisomesfrom green leaves had two catalase subunits of around 55 kDaeach. Results of translation in vitro indicated that the 54-and 56-kDa subunits were translated from distinct mRNAs andlevels of both mRNAs increased in the endosperms during germination,prior to increases in levels of catalase proteins. In the hypocotyls,the 56-kDa subunit seemed to be synthesized constitutively.
1Present addresses: YO, Toyota Central Institute, 31-9 Musashizuka,Nagabuchi, Nagakute, Aichi 480-11, Japan 相似文献
105.
Yoshihiro Kuroda Yoshitaka Maeda Shinichi Sawa Kiyohiro Shibata Kazuhide Miyamoto Terumichi Nakagawa 《Journal of peptide science》2003,9(4):212-220
Pathogenic prion proteins (PrP(Sc)) are thought to be produced by alpha-helical to beta-sheet conformational changes in the normal cellular prion proteins (PrP(C)) located solely in the caveolar compartments. In order to inquire into the possible conformational changes due to the influences of hydrophobic environments within caveolae, the secondary structures of prion protein peptides were studied in various kinds of detergents by CD spectra. The peptides studied were PrP(129-154) and PrP(192-213); the former is supposed to assume beta-sheets and the latter alpha-helices, in PrP(Sc). The secondary structure analyses for the CD spectra revealed that in buffer solutions, both PrP(129-154) and PrP(192-213) mainly adopted random-coils (approximately 60%), followed by beta-sheets (30%-40%). PrP(129-154) showed no changes in the secondary structures even in various kinds of detergents such as octyl-beta-D-glucopyranoside (OG), octy-beta-D-maltopyranoside (OM). sodium dodecyl sulfate (SDS), Zwittergent 3-14 (ZW) and dodecylphosphocholine (DPC). In contrast, PrP(192-213) changed its secondary structure depending on the concentration of the detergents. SDS, ZW, OG and OM increased the alpha-helical content, and decreased the beta-sheet and random-coil contents. DPC also increased the alpha-helical content, but to a lesser extent than did SDS, ZW, OG or OM. These results indicate that PrP(129-154) has a propensity to adopt predominantly beta-sheets. On the other hand, PrP(192-213) has a rather fickle propensity and varies its secondary structure depending on the environmental conditions. It is considered that the hydrophobic environments provided by these detergents may mimic those provided by gangliosides in caveolae, the head groups of which consist of oligosaccharide chains containing sialic acids. It is concluded that PrP(C) could be converted into a nascent PrP(Sc) having a transient PrP(Sc) like structureunder the hydrophobic environments produced by gangliosides. 相似文献
106.
T. Hishinuma Grace S. P. Yu M. Takabatake Y. Nakagawa K. Ito M. Nishikawa M. Ishibashi K. Suzuki M. Matsumoto T. Toyoda M. Mizugaki 《Prostaglandins, leukotrienes, and essential fatty acids》1996,54(6):445-449
We microanalyzed 2,3-dinor-6-keto-prostaglandin F1α (2,3-dinor-6-keto-PGF1α 1) and 11-dehydrothromboxane B2 (11-dehydro-TXB2, 2) in human urine. Samples containing a [2H4]-analogue as an internal standard were extracted by chromatography using Sep Pak tC18 and silica gel. The compounds were then analysed by means of the lactone ring opening reaction and dimethylisopropylsilylation. The conversion of 1 to 1-methyl ester (ME)-propylamide (PA)-9,12,15-dimethylisopropylsilyl (DMIPS) ether derivative and of 2 to 1-ME-6-methoxime (MO)-9,12,15-tris-DMIPS ether derivative was followed by gas chromatography/selected ion monitoring (GC/SIM). Interfering substances from the urine matrix were eliminated during GC/SIM analysis using a DB-5 column. We were able to detect 1 (222–1031 pg/mg creatinine) and 2 (18–155 pg/mg creatinine) in human urine. Furthermore, the thromboxane/prostacyclin (IX/PGI) ratio in the urine of diabetics was higher than that of healthy volunteers. This method can be used to determine the TX/PGI balance in human urine. 相似文献
107.
To evaluate the spawning success of male Japanese minnows,Pseudorasbora parva, and female mate choice, spawning behaviour was observed under both artificial and experimental conditions. Larger males
had larger territories and greater reproductive success. The body weight of territorial males decreased during the maintenance
of territories, while that of non-territorial males increased significantly. When the weight of non-territorial males exceeded
that of territorial males, the former began to establish new territories on the substrate, suggesting a conditional strategy
by non-territorial males to trade off immediate reproductive success with growth and hence improve future reproductive success.
Females chose males with larger body size, probably based on dominance rank rather than the quality (or size) of territory.
It was concluded that females choose males of higher dominance rank and that males compete for large territories, both of
which play an important part in male reproductive success. 相似文献
108.
Effect of triethylenepentaminehexaacetic acid on the renal damage in cadmium-treated Syrian hamsters 总被引:2,自引:0,他引:2
Toshiaki Shibasaki Q. -Y. Xu Iwao Ohno Fumio Ishimoto Osamu Sakai 《Biological trace element research》1995,50(2):157-165
Cadmium (Cd)-induced nephropathy was treated by triethylene-pentaminehexaacetic acid (TTHA) in male Syrian hamsters. Hamsters
injected three times a week with 3 mg/kg body wt CdCl2 showed proteinuria, urinaryN-acetyl-β-d-inglucosaminidase (NAG), and fractional excretion of sodium (FENa) when compared to saline-injected control. Cd-treated hamsters
injected ip with TTHA 10 mg/kg body wt five times a week showed reduction of renal damage, including reductions in urinary
protein (from 6.7±2.2 to 4.3±0.5 mg/d) and NAG (0.17±0.06 to 0.04±0.02 U/d). Urinary excretion of Cd was significantly increased
(from 87±51.3 to 3052±1485 mg/L) by TTHA administration. Cd concentration in renal cortical tissue was slightly reduced (26.4±3.0
to 21.8±2.7 mg/g. protein). Excretion of malondialdehyde (MDA) was increased only in Cd-injected hamsters (to 2.1±1.6 nM/L), and elevated MDA in renal cortical tissue was not reduced by the administration of TTHA (1041±105 vs 1104±358 nM/g protein). Glutathione (GSH) concentration in the renal cortex was significantly elevated after Cd administration and further
increased after TTHA administration (5.5±2.1 to 9.8±2.0 μg/50 mg protein). There were no marked effects on creatinine clearance
(Ccr) and hematocrit. Moreover, renal morphological changes were improved significantly by treatment with TTHA.
We demonstrated the efficacy of TTHA in the treatment of Cd-induced nephropathy in hamsters. Although the precise mechanism
of the TTHA effects on Cd-induced nephropathy has not been elucidated, it might involve GSH reducing the elevated MDA concentration
in renal tissue. 相似文献
109.
N. Ohmiya Shinsuke Saga Masaharu Ohbayashi Ken-ichi Kozaki Osamu Miyaishi Miya Kobayashi Shiro Kasuya Tomiyasu Arisawa Hidemi Goto Tetsuo Hayakawa 《Histochemistry and cell biology》1997,108(1):27-34
An association between eosinophils and tissue damage has been observed in numerous disorders. However, few reports have addressed
the role of infiltrating eosinophils in gastric ulcer healing. The aim of this study was to investigate the kinetics and role
of eosinophils infiltrating experimental chronic gastric ulcers in the rat. We developed a monoclonal antibody against human
matrix metalloproteinase 1 (MMP1) purified from conditioned culture medium of human skin fibroblasts. Acetic acid-induced
gastric ulcers were resected from rats on days 1, 3, 5, 10, 20, 40, and 180 after the days of induction (day 0). Tissue specimens
were immunostained with this antibody and examined with an electron microscope. Few eosinophils were observed in the granulation
tissue until day 20. By days 40 and 180, MMP1-positive eosinophils had increased in the granulation tissue of open ulcers.
Azan staining revealed dispersed collagen fibers around infiltrating eosinophils. In contrast, scars demonstrated few eosinophils
in fibrous tissue on days 40 and 180. Eosinophils which express MMP1 infiltrate granulation tissue at the chronic stage of
gastric ulceration. The results suggest that eosinophils may play a role in tissue remodeling and deterioration of ulceration.
Accepted: 18 March 1997 相似文献
110.
Hanger Christopher C.; Presson Robert G. Jr.; Okada Osamu; Janke Steven J.; Watkins John J.; Wagner Wiltz W. Jr.; Capen Ronald L. 《Journal of applied physiology》1997,82(4):1283-1289
Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada,Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonarycapillary networks. J. Appl. Physiol.82(4): 1283-1289, 1997.Individual pulmonary capillaries are notsteadily perfused. By using in vivo microscopy, it can readily bedemonstrated that perfusion continually switches between capillarysegments and between portions of the network within a single alveolarwall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. Tocalculate the probability that perfusion patterns could occur bychance, it is necessary to know the total number of possible perfusionpatterns in a given capillary network. We developed a computer programthat can determine every possible perfusion pattern for any givencapillary network, and from that information we can calculate whetherperfusion of individual segments in the network is random. With theresults of the computer program, we have obtained statistical evidencethat some capillary segments in a network are nonrandomly perfused. 相似文献