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121.
Masato Hirata Takafumi Hamachi Eiichi Suematsu Toshitaka Koga 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,763(4):339-345
Effects of N-formyl chemotactic peptides on the Ca2+ influx and efflux were investigated in guinea-pig peritoneal macrophages using an isotope tracer. fMet-Leu-Phe did not enhance the influx of 45Ca2+ into macrophages, whereas it stimulated the efflux of 45Ca2+ from macrophages at concentrations ranging from 10?10 M to 10?7 M. fMet-Met-Met and fMet-Leu also stimulated the 45Ca2+ efflux, albeit at much higher concentrations, while there was no stimulation with fMet. The mitochondrial inhibitors, oligomycin and NaN3, did not modify the 45Ca2+ efflux induced by the chemoattractants, yet they did induce the release of 45Ca2+ from the mitochondria. On the other hand, higher concentrations of the calmodulin antagonists, chlorpromazine and trifluoperazine, induced the release of 45Ca2+ from the NaN3-insensitive Ca2+ store site and mimicked the enhancement of the 45Ca2+ efflux by N-formyl chemotactic peptides. Thus, N-formyl chemotactic peptides appear to increase the levels of intracellular free Ca2+ in guinea-pig peritoneal macrophages, probably by inducing the release of Ca2+ from the NaN3-insensitive Ca2+ store site. 相似文献
122.
Methodology is presented for the determination of growth yield (Y(g)) and maintenance coefficient (m) for carbon utilization of plant cells grown in suspension culture. Estimation of Y(g) and m requires measurements of specific growth rate (micro) and specific rate of substrate uptake (q) at different growth limiting substrate concentrations. Batch culture of tobacco cells did not permit evaluation of Y(g) and m because micro is constant and maximal during most of the growth cycle. In batch culture, the period of declining specific growth rate is extremely brief because of the rapid transition from logarithmic growth to stationary phase. This occurs because the K(m) for growth is relatively small compared to the initial sucrose concentration. Thus, when the substrate level reaches the K(m), the large mass of cells rapidly depletes the remaining substrate. In contrast, semicontinuous culture facilitates the determination of Y(g) and m because various steady-state growth rates can be achieved. Mathematical expressions were developed to determine the effective values of micro and q over the semicontinuous replacement interval. The validity of this approach was verified by conducting simulations using experimentally determined parameters. 相似文献
123.
N Nakamura Y Tsutsumi S Kimata M Sawada G Hasegawa Y Kitagawa K Nakano M Kondo H Nakao S Makino 《Endocrinologia japonica》1991,38(5):523-526
To determine whether environmental factors could affect the incidence of diabetes in RT6.1+ lymphocytes-depleted diabetes resistant (DR) BB rats, we tested polyinosinic-polycytidylic acid (Poly I:C), as an immune activator, in conjunction with anti-RT6.1 antibody in DR-BB rats which were bred in a specific pathogen free (SPF) condition. Diabetes was induced by the combined administration of poly I:C and anti-RT6.1 antibody. The use of poly I:C or anti-RT6.1 antibody alone did not cause diabetes. These results suggest that RT6.1+ T lymphocytes regulate autoimmune diabetes and that non-specific immune activation caused by environmental factors plays a key role in inducing diabetes in DR-BB rats. 相似文献
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D K Ann J Hasegawa J L Ko S T Chen N M Lee H H Loh 《The Journal of biological chemistry》1992,267(11):7921-7926
We have recently identified and sequenced the cDNA for an opioid-binding protein with homologies to cell adhesion molecules (OBCAM) (Schofield, P. R., McFarlard, K. C., Hayflick, J. S., Wilcox, J. N., Cho, T. M., Roy, S., Lee, N. M., Loh, H. H., and Seeburg, P. H. (1989) EMBO J. 8, 489-495). Several lines of evidence using antibodies suggest that OBCAM may play a functional role in NG108-15 neuroblastoma x glioma cells, a useful model system that contains a homogeneous population of delta-opioid receptors. A logical extension of this research is to further test this hypothesis. As part of this study, NG108-15 cells were stably transfected with either sense or antisense sequences of a portion of pROM, the rat cDNA for OBCAM. [3H] Diprenorphine binding was greatly reduced in antisense-transfected cells relative to non-transfected cells. Binding to alpha 2-adrenergic, muscarinic, and insulin receptors was unaffected. These results further support the notion that OBCAM or its analogue is part (or a subunit) of an opioid receptor. Furthermore, our observation of an apparently specific reduction in opioid binding in these transfected cells suggests that they may provide a novel genetic approach for studying regulation of the opioid receptor in this defined cell line. 相似文献
126.
T Takabatake M Hasegawa T Nagano M Hirobe 《The Journal of biological chemistry》1992,267(7):4613-4618
The O2-. production by aerobically cultured Escherichia coli in the presence of benzofurazan (1), 4,7-dimethylbenzofurazan (2), 4,7-dibromobenzofurazan (3), 4-bromo-6-cyanobenzofurazan (4), and 4,7-dicyanobenzofurazan (5) was examined by using the cytochrome c reduction method in order to elucidate the mechanism of cytotoxicity of benzofurazans. Adding compound 5 to E. coli cell suspension caused cytochrome c reduction, which was completely inhibited by superoxide dismutase. The rate of cytochrome c reduction was in the order of 1 = 2 = 3 less than 4 less than 5, which correlates well with that of the reduction potentials of these benzofurazans. Adding glucose to the E. coli cell suspension-compound 5-cytochrome c system accelerated the rate of cytochrome c reduction. The formation of 4,7-dicyanobenzofurazan anion radical in the cell suspension-compound 5-glucose system in the absence of O2 was followed by ESR spectroscopy. The ESR signal of the anion radical disappeared when O2 was added. Compound 5 was shown to have an approximately 10-fold greater increasing effect on the flux of O2-. by E. coli than paraquat (PQ) by the cytochrome c reduction method. The results were confirmed by the electrochemical method with an oxygen electrode. However, compound 5 had a bacteriostatic, but not lethal, effect, while PQ had both effects. The effect of compound 5 and PQ on lethality of E. coli showed a dramatic difference when E. coli was exposed to these two compounds and washed prior to testing the effects of that exposure. This difference probably arose because compound 5 readily leaked from the cells during dilution and plating. Also, the reduced form of compound 5 exits from the cells more readily than the reduced form of PQ and then generates O2-. in the medium by autoxidation. This suggests the importance of the intracellular production of O2-., rather than the extracellular production of O2-., for lethal effect. 相似文献
127.
K Hanada M Nishijima M Kiso A Hasegawa S Fujita T Ogawa Y Akamatsu 《The Journal of biological chemistry》1992,267(33):23527-23533
We previously isolated a temperature-sensitive Chinese hamster ovary cell mutant (strain SPB-1) with thermolabile serine palmitoyltransferase, which is involved in the first step of sphingolipid synthesis (Hanada, K., Nishijima, M., and Akamatsu, Y. (1990) J. Biol. Chem. 265, 22137-22142). In this study, sphingolipid-deficient culture medium was used to examine the effect of exogenous sphingolipids on the cell growth of SPB-1. When cultivated in the sphingolipid-deficient medium, SPB-1 cells ceased growing at non-permissive temperatures. Under these conditions, de novo sphingolipid synthesis ceased in the SPB-1 cells, resulting in a decrease in levels of sphingomyelin and ganglioside sialyl lactosylceramide (GM3), whereas the parental CHO-K1 cells grew logarithmically with normal sphingolipid synthesis. Exogenous sphingosine restored the contents of both sphingomyelin and GM3 in the SPB-1 cells near to the parental levels through metabolic utilization and allowed the mutant cells to grow even at the non-permissive temperature. Similarly, exogenous sphingomyelin restored the sphingomyelin levels and only partly the GM3 levels and also suppressed the temperature-sensitivity of the SPB-1 cell growth. In contrast, exogenous glucosylceramide, which restored the GM3 levels but not the sphingomyelin levels, failed to suppress the temperature sensitivity of the SPB-1 cell growth. Combination of exogenous sphingomyelin with ceramide, glucosylceramide, GM3, or sphingoid bases did not show any synergistic or additive effect on the SPB-1 cell growth enhancement, compared with sphingomyelin alone. The results indicated that the temperature sensitivity of the SPB-1 cell growth was due to the lack of cellular sphingolipids, possibly that of sphingomyelin. 相似文献
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