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1.
Abstract The stability of clathrate hydrates encaging highly polar guests has been investigated in order to explain the experimental observation that some amines form clathrate hydrates but alcohols act as inhibitor to hydrate formation. We choose methylamine and methanol as guest species and examine the stable structure, at which the total potential energy has a minimum value. At the local minima of those two hydrates, the potential energies of water-water and guest-water, and their hydrogen bonded networks are compared. It is found that methanol does not retain the host lattice structure, while the host-network structure is kept in the presence of methylamine. It is shown that the difference in the magnitude of the partial charge on the hydrogen atom between the hydroxyl and amino groups plays a much more significant role on the stability of both clathrate hydrates than the difference in molecular geometry. This is supported from the result of a methylamine-like model that has the same partial charges on the atoms in the hydrophilic site as methanol. 相似文献
2.
Andoh Tomio; Itoh Hideki; Watanabe Itaru; Sasaki Toshio; Higashi Tomoko 《American journal of physiology. Cell physiology》2001,281(6):C1871
Substance P is known to modulate neuronal nicotinicacetylcholine receptors (nAChRs) in the sympathetic nervous system.There are two conflicting proposals for the mechanism of this effect, an indirect action mediated by protein kinase C (PKC) and a direct interaction with receptor subunits. We studied the mechanisms of thiseffect in PC-12 cells. Substance P enhanced the decay of thenicotine-induced whole cell current. This effect was fast in its onsetand was not antagonized by guanosine5'-O-(2-thiodiphosphate), a G protein blocker, orstaurosporine, a nonselective PKC blocker. Staurosporine failed toreverse the inhibition by 1-oleoyl-2-acetyl-sn-glycerol (OAG), a synthetic diacylglycerol analog known to activate PKC. Theinhibitory effects of the peptide and OAG were preserved in excisedpatches, but substance P applied to the extra patch membrane wasineffective in the cell-attached patch configuration. We conclude thatsubstance P modulates neuronal nAChRs most likely by direct interactions with the receptors but independently from activation ofPKC or G proteins and that PKC does not participate in modulation by OAG. 相似文献
3.
Hideki Takahashi Ko Shimamoto Yoshio Ehara 《Molecular & general genetics : MGG》1989,216(2-3):188-194
Summary In order to study possible functions of the inclusion body matrix protein (IBMP) encoded by gene VI of cauliflower mosaic virus (CaMV), the XbaI fragment containing the gene VI of a Japanese strain of CaMV (CaMV S-Japan) was transferred to tobacco plants by Ti mediated transformation. Eight out of 18 kanamycin resistant plants (40%) expressed detectable levels of IBMP. Those transgenic plants expressing IBMP produced leaves with light green color, and their growth was suppressed as compared with control plants. Symptom-like necrotic spots also appeared on the leaves and stems of the mature transgenic plants. Furthermore, in these transgenic plants, pathogenesis-related proteins 1a, 1b and 1c were highly expressed and the activity of 1,3--glucanase was increased up to eightfold. From these results, we concluded that expression of the IBMP is associated with symptom development. 相似文献
4.
Characterization of Vegetal Plate Cells Separated from Cytochalasin B-Treated Blastulae of the Sea Urchin, Clypeaster japonicus 总被引:2,自引:2,他引:0
Hideki Katow 《Development, growth & differentiation》1989,31(5):439-446
Vegetal plate forming cells (VPCs) of the vegetal plate blastulae of the sea urchin, Clypeaster japonicus , had a layer of microfilaments on the basal side. The VPCs specifically protruded from the embryos after a treatment with 1 μg/ml of cytochalasin B (CB). Based on scanning electron microscopy, unlike other epithelial cells the protruded VPCs possessed neither cilium nor microvilli on their surface. The protruded VPCs were easily separated from the embryos by stirring the embryo suspension with pipette. An in vitro immunohistochemistry using a primary mesenchyme cell (PMC) surface-specific monoclonal antibody (MAb) raised against PMCs of Strongylocentrotus purpuratus showed that the MAb also specifically bound to the PMCs in mesenchyme blastulae of C. japonicus . The MAb bound in 81% of the separated VPCs in C. japonicus vegetal plate blastulae examined. However, the MAb binding occurred only after the separated VPCs were incubated in artificial sea water (ASW) for at least 1 hr. In the VPC-deprived embryos, gastrulation occurred after they were transferred to normal ASW. However, the PMCs and the spicules were not formed in these embryos.
In conclusion, a majority of the VPCs separated from the CB-treated blastulae were presumptive PMCs. These VPCs provide an excellent source of presumptive PMCs. 相似文献
In conclusion, a majority of the VPCs separated from the CB-treated blastulae were presumptive PMCs. These VPCs provide an excellent source of presumptive PMCs. 相似文献
5.
Yoshinori Nio MD Takahiro Shiraishi Michihiko Tsubono Hideki Morimoto Chen-Chiu Tseng Kazuya Kawabata Yoshikazu Masai Manabu Fukumoto Takayoshi Tobe 《Biotherapy》1992,4(2):81-86
The present study was designed to evaluate the effects of a recombinant human G-CSF (rhG-CSF) and a mutein G-CSF(KW-2228) on leucopenia and tumor growth in mice treated with 5-fluorouracil (5-FU). In normal mice, the number of leucocytes (white blood cell, WBC) reached the peak 12 hours after a single injection of either type of G-CSF and decreased to the normal level after 24 hours. Daily administration induced a continuous increase in the WBC count, however, administrations at intervals did not. Meth-A fibrosarcoma was subcutaneously inoculated into the backs of syngeneic BALB/c mice. The mice were treated with 5-FU alone or with G-CSFs. Chemotherapy with 5-FU alone resulted in leucopenia and an insignificant inhibition of tumor growth. The conjunctive administration of G-CSFs with 5-FU resulted in a significantly augmented inhibition of tumor growth, and leukopenia was not seen. This augmenting effect was more prominent with KW-2228.These results suggest that in 5-FU chemotherapy G-CSFs may be beneficial in restoring the number of leucocytes from leucopenic state and in augmenting the tumor inhibitory effect. Furthermore, KW-2228 may be more beneficial than the natural type rhG-CSF. 相似文献
6.
Summary Long-term cultivation of anchorage-independent animal cells immobilized within porous biomass support particles (BSPs) using a gas-stirred circulating bed fermentor (CBF) was investigated. Inoculation of mouse myeloma MPC-11 (ATCC CCL 167) cells into reticulated polyvinyl formal resin BSPs (3 × 3 × 3 mm; mean pore diameter, 60 m; porosity, 0.88) and the repeated batch culture of inoculated cells were performed under gentle circulation of BSPs, induced by sparging air from the base of the fermentor. The glucose uptake rate of cells decreased in the initial period just after the start of circulation, since a relatively large number of cells leaked from the BSPs. After that period, the uptake rate gradually increased and the leakage of cells diminished. In the meantime, when inoculated cells were incubated statically by introducing air into the upper part of the fermentor for the initial several days before circulating the BSPs, glucose consumption became very rapid and cell density in the BSPs reached at least 107 cells/cm3 BSP. Thus, a long-term cultivation without significant leakage of cells and with high cell density in BSPs was successfully achieved in the CBF-BSP system.Offprint requests to: H. Yamaji 相似文献
7.
Kimitoshi Umeda Hideki Tateda 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1985,157(6):831-836
Summary The physiology and morphology of visual interneurons in the lobula complex of the fleshfly,Boettcherisca peregrina, were studied using intracellular recordings and intracellular cobalt stainings, respectively. Using responses to movements of a spot of light and on-off stimuli at single positions, we classified the interneurons into five physiological groups ON, OFF, ON-OFF, nondirectional motion sensitive (NDM) and directional motion sensitive (DM) neurons. They could be further divided into four morphological types, depending on the location and extent of their dendrites and terminal branches. 相似文献
8.
Hideki Ozawa Takao Iwaguchi Tateshi Kataoka 《Cancer immunology, immunotherapy : CII》1986,23(1):73-77
Summary Spleen cells of BALB/c mice hyperimmunized with a transplantable methylcholanthrene-induced sarcoma Meth A (Meth A-Im-SPL) inhibited the growth of Meth A tumor in vivo in a tumor neutralizing test. Meth A-Im-SPL did not neutralize another antienically distinct sarcoma, Meth 1, indicating that the antitumor activity is tumor specific. Lyt-1+2– cells of Meth A-Im-SPL (Im-Lyt-1+2–) were the effectors since in vitro treatment of Meth A-Im-SPL with anti-Thy 1.2 or anti-Lyt 1.2 antibody plus complement completely abrogated their neutralizing activity, whereas treatment with anti-Lyt 2.2 plus complement did not. To further confirm the effector activity of Im-Lyt-1+2– cells, T cell subpopulations were separated from Meth A-Im-SPL by the panning method. The purified Im-Lyt-1+2–, but not Im-Lyt-1+2+ cells neutralized the tumor in athymic nu/nu mice as efficiently as in +/+ mice, suggesting that the donor Im-Lyt-1+2– cells but not recipient T cells were primarily responsible for neutralizing the tumor. The present study, however, did not exclude the possible contribution of recipient T cells to the tumor neutralization and this is open to further investigation.Abbreviations Meth A-Im-SPL
Meth A-immune mouse spleen cells
- Meth 1-Im-SPL
Meth 1-immune mouse spleen cells
- sIg+ cells
surface immunoglobulin positive cells
- moAb
monoclonal antibody 相似文献
9.
The electrical responses of the taste cell of the rat to chemical stimuli were studied by means of microelectrode techniques. Although large positive potential changes in the taste cell were usually elicited by taste stimuli, the response was a small negative potential change with respect to surrounding tissues if the microelectrode was thrust deeply into the taste bud. Both FeCl3 and cocaine produced a positive change in the steady potential. If this new potential is larger than a certain equilibrium potential, reversal of the polarity of the potential change caused by a taste stimulus is observed. Gamma-aminobutyric acid and acetylcholine had no effect on the receptor steady potential nor on the receptor responses elicited by taste stimuli. 相似文献
10.
Hisashi Miyazaki Masatoshi Iida Yoshimasa Matsunaga Toshihiko Fujii Keiko Nambu Hideki Amejima Yoshinori Oh-e Hideo Furukawa Yukiharu Matsui Yasunobu Sohmura Masahisa Hashimoto 《Biotherapy》1989,1(1-2):47-57
The mode of antitumor action of rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation with respect to time course, dose-response relationships and selectivity of the effects. The maximal cytotoxic effect on tumor cells revealed by inhibition of DNA synthesis and maximal lesional effect on tumor vasculature revealed by change in blood pool-size in the tissue were detected at 30 min and I h after administration of rHu-TNF, respectively. The dose-response relationship between cytotoxic and tumoricidal effects of rHu-TNF was irrespective of administration route. ED50s of these antitumor effects afteri.v. administration of rHu-TNF were about 50 times as high as ED50s afteri.t. administration. ED50 ofi.t. given rHu-TNF for vascular effect was about 20 times as high as that for cytotoxicity while ED50 ofi.v. rHu-TNF for vascular effect was only 2–3 times as high as that for cytotoxicity. The whole body autoradiographies with [125I] HSA giveni.v. to see the blood influx into tumor tissue and [14C]thymidine given i.v. to see DNA synthesis in the whole body after administration of rHu-TNF revealed that the distribution of radioactivity was markedly changed in the tumor alone without any detectable change in other whole body tissues.In conclusion, thein vivo antitumor effect of rHu-TNF giveni.t. ori.v., appears to be exerted through the direct action on Meth A sarcoma rather than indirectly on tumor vasculature. Under present conditions, the effect of rHu-TNF in the whole body tissues seems rather selective on cells and vasculature of the tumor. 相似文献