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71.
Release of Excitatory Amino Acids from Cultured Hippocampal Astrocytes Induced by a Hypoxic-Hypoglycemic Stimulation 总被引:2,自引:0,他引:2
Tadanori Ogata† Yoichi Nakamura Taiho Shibata† Kiyoshi Kataoka 《Journal of neurochemistry》1992,58(5):1957-1959
An excess release of excitatory amino acids (EAA) is an important factor for postischemic brain damage. In the present communication, we demonstrate that cultured hippocampal cells release EAA after hypoxic-hypoglycemic treatment. The amounts of EAA released from astrocytes were appreciably above those released from neurons. Furthermore, the amount of aspartate released from astrocytes was comparable to that of glutamate, although the endogenous content of aspartate was one-fifth that of glutamate. The endogenous content of aspartate in astrocytes increased even after hypoxic-hypoglycemic treatment. These results suggests that ischemic neuronal death is due, at least in part, to the excitotoxicity of aspartate and glutamate derived from surrounding astrocytes. 相似文献
72.
73.
Kiyoshi Ohkawa Takashi Hatano Naoko Takizawa Kazue Shinmoto Kyosuke Yamada Makoto Matsuda Koji Takada Yutaka Tsukada 《In vitro cellular & developmental biology. Animal》1992,28(6):449-454
Summary A human yolk sac tumor cell line, TG1, which was established from a testicular yolk sac tumor, was found to replicate continuously
in a chemically defined medium supplemented with Na2SeO3 (ISRPMI). TG1 produced several plasma proteins and growth factors: albumin, alpha-fetoprotein (AFP), ferritin, carcinoembryonic
antigen, beta-2-microglobulin, polyamine, neuron specific enolase, tissue polypeptide antigen, transferrin (Tf), epidermal
growth factor, and platelet derived growth factor. By analysis of lectin (LcHA)-affinity electrophoresis, to examine the microheterogeneity
of carbohydrate chains of synthetic glycoproteins, TG1 cells cultured with ISRPMI produced only LcHA reactive Tf and AFP based
on core fucose attached to asparagine-linkedN-acetylglucosamine residues instead of LcHA-nonreactive Tf and AFP produced by TG1 cells cultured with fetal bovine serum
(FBS)-containing medium.α1-6 Fucosyltransferase activity was significantly greater in the TG1 cells cultured with ISRPMI (39.9±1.5 pmol · h−1 · mg−1 protein) than cultured with FBS-containing media (18.2±1.2 pmol · h−1 · mg−1 protein). These results have indicated that the selective increase ofα1-6 fucosyltransferase occurred when the cells were cultured with the FBS-free synthetic media. 相似文献
74.
75.
Summary Deficiency of inorganic phosphate caused the hyper production of invertase and the derepression of acid phosphatase in a continuous culture ofSaccharomyces carlsbergensis. The specific invertase activity was 40,000 enzyme units per g dry cell weight at a dilution rate lower than 0.05 h–1 with a synthetic glucose medium of which the molecular ratio of KH2PO4 to glucose was less than 0.006. This activity is eight fold higher than in a batch growth and 1.5 fold as much as the highest enzyme activity observed so far in a glucose-limited continuous culture.For the hyper production of invertase, it is necessary to culture the yeast continuously by keeping the Nyholm's conservative inorganic phosphate concentration at less than 0.2 m mole per g dry weight cell. The derepression of acid phosphatase brought about by phosphate deficiency, was similar in both batch and continuous cultures.Nomenclature D
dilution rate of continuous culture (h–1)
- Ei
invertase concentration in culture (enzyme unit l–1)
- Ep
acid phosphatase concentration in culture (enzyme unit l–1)
- P
inorganic phosphate concentration in culture (mM)
- S
glucose concentration in culture (mM)
- X
cell concentration in culture (g dry weight cell l–1)
Greek Letter
specific rate of growth (h–1)
Suffix f
feed
- 0
initial value 相似文献
76.
Intravenous administration of short-chain fatty acid (SCFA), such as propionate, butyrate, valerate and caproate, caused a transient increase in transmural potential difference (p.d.) across the small intestine of rat . There was a sigmoid relationship between the change in the p.d. and the logarithm of the dose of SCFA. The median effective dose of propionate, n-butyrate, n-valerate and n-caproate, which was calculated from the each dose-response curve obtained from the terminal ileum, 1.31, 1.43, 0.83 and 0.81 μmole, respectively. Repeated administrations of the same dose of propionate evoked progressively smaller response. The dose-response curve of propionate was shifted to the left by neostigmine and to the right by atropine, suggesting that the action of SCFA may be mediated by acetylcholine, which was released from a nerve ending. 相似文献
77.
Kiyoshi Mizuuchi Martin Gellert Robert A. Weisberg Howard A. Nash 《Journal of molecular biology》1980,141(4):485-494
Catenanes (interlocked circular DNA molecules) are the exclusive products of the bacteriophage λ integrative recombination reaction in vitro when the substrate is a supercoiled DNA molecule containing both the attP and attB sites. It is proposed that the catenation results from the superhelical form of the substrate DNA. We also show that both circular DNA products of a single recombination event can be recovered as superhelical molecules with a superhelical density approximately that of the substrate DNA. The recombination reaction must therefore occur as a coupled process which does not permit free rotation around single-strand breaks at any stage. 相似文献
78.
Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach 总被引:1,自引:0,他引:1
Shimazaki Ken-ichiro; Sakaki Takeshi; Kondo Noriaki; Sugahara Kiyoshi 《Plant & cell physiology》1980,21(8):1193-1204
Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO2 under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO2.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO2 at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO2-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO2was due to superoxide radicals (O2). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO2-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D2O. These results suggest thatlipid peroxidation in SO2-fumigated leaves was due to singletoxygen 1O2 produced from O2. (Received May 15, 1980; ) 相似文献
79.
80.
Kiyoshi Mishima 《生物化学与生物物理学报:生物膜》1981,648(2):162-168
Depolarized light scattering has been used to investigate the hydrocarbon chain packing of phospholipids in vesicles below the phase transition and ordering of their chains above the phase transition. The chain packing and ordering have been demonstrated for vesicles of l-α-dipalmitoylphosphatidylethanolamine and some phosphatidylcholines of different hydrocarbon chain lenghts. Anisotropy ratios for phospholipid vesicles could be determined by measuring depolarization ratios for several vesicle sizes at low concentrations of the lipids. The following results were obtained. Hydrocarbon chains of l-α-dimyristoyl and distearoylphosphatidylcholines below their phase transitions pack at tilting angles in good agreement with X-ray diffraction data. On the other hand, hydrocarbon chains of dipalmitoylphosphatidylethanolamine pack perpendicular to the bilayer surface. Values of the averaged order parameter for dimyristoyl, dipalmitoyl and distearoylphosphatidylcholines at 2.5°C above their phase transition are all the same and the value for dipalmitoylphosphatidylcholine is in agreement with results from 2H-NMR experiments. The value of the order parameter for dipalmitoylphosphatidylethanolamine is slightly larger than that for dipalmitoylphosphatidylcholine. 相似文献