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J A Cox A Y Jeng P M Blumberg A I Tauber 《Journal of immunology (Baltimore, Md. : 1950)》1987,138(6):1884-1888
The phorbol myristate acetate (PMA) stimulation of the human neutrophil NADPH-oxidase has been demonstrated through the activation of protein kinase C (PK-C), using light membrane fractions from nitrogen-cavitated cells. Both arachidonic acid (AA) and sodium dodecyl sulfate (SDS) can also generate an active oxidase in cellfree systems. That the source of O2- with AA and SDS activation is the same NADPH-oxidase as previously studied was confirmed by the similar pH optima and Km values for NADPH as those previously described for the O2- -generating activity harvested from pre-stimulated human neutrophils. In contrast to the stimulation by PMA, however, the stimulation of the NADPH-oxidase by AA and SDS does not appear to require protein kinase C activation: the action of AA and SDS is independent of the addition of PK-C cofactors to the system, and the inhibitor of PK-C activity, H-7, had no effect on the stimulation by AA or SDS. AA and SDS activation are comparable, but the level of NADPH-oxidase expression is sixfold greater with each of these agents than that obtained with a reconstituted PK-C system. The basis of this difference in oxidase expression is unclear, but these findings suggest strongly that although activated PK-C is capable of stimulating a dormant NADPH-oxidase in a cellfree system, this is not the sole pathway for oxidase activation. 相似文献
3.
Luc C. Duchesne R. S. Jeng M. Hubbes M. B. Sticklen 《Trees - Structure and Function》1990,4(4):187-190
Summary The accumulation of mansonones E and F was investigated in Ulmus americana L. seedlings 5 weeks after inoculation with three aggressive and three non-aggressive isolates of Ophiostoma ulmi (Buism.) Nannf. The three non-aggressive isolates stimulated significantly more mansonone E and F accumulation than the three aggressive isolates of O. ulmi. Mansonone induction also varied within both the aggressive and the non-aggressive groups. Aggressive and non-aggressive isolates were recovered in equal frequencies from the inoculation wounds, whereas the aggressive isolates were recovered more frequently than the non-aggressive isolates 15 cm and 25 cm up the seedlings' stem. Vascular browning in the outer xylem of the seedlings correlated with mansonone E and F accumulation. Mansonone accumulation in U. americana seedlings is therefore associated with vascular browning and a reduction in fungal spread. 相似文献
4.
Cytosolic diacylglycerol kinase was irreversibly inactivated by 5'-AMP since the enzyme remained less active after the removal of 5'-AMP by P-10 gel chromatography. The inactivation was time-dependent, suggesting the involvement of a covalent bond modification. A reconstitution experiment detected a rat brain cytosolic mediator for the effect of 5'-AMP. A protein kinase rich fraction prepared from rat liver was also capable of restoring the sensitivity of diacylglycerol kinase-II to 5'-AMP. We propose that 5'-AMP-activated protein kinase is the mediator which inactivates diacylglycerol kinase-II, possibly by phosphorylation. 相似文献
5.
To preserve the nucleophilicity of amino compounds during conjugative radioiodination, a new method for converting primary amines to phenolic secondary amines was developed. Amino acids were used as model compounds for establishing optimal conditions for the reductive amination. In the first step of the reaction, the aldehyde group of 4-hydroxybenzaldehyde (formylphenol) was reacted reversibly with an amino group to form an imine. The irreversible attachment of formylphenol to the amino group was accomplished by reduction of the imine with sodium cyanoborohydride. The pH optimum for the reaction was 5.0. Higher temperature has favorable effects on the rate and extent of the conjugation. Phenolic derivatives of amino compounds suitable for radioiodination are produced by the reactions described. 相似文献
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The growth rate of an oceanic dinoflagellate, Ceratium teres Kofoid, was investigated in the Sargasso and Caribbean Seas from September 1989 to July 1990 using the cell cycle analysis method. Estimated growth rates ranged from 0.29 to 0.58 day?1 and were 1.5–7.2 times higher than generally accepted rates for oceanic dinoflagellates. The higher rates in this report were mainly due to an improvement in techniques that determine the duration of a terminal cell cycle phase in situ. The day-to-day variation in growth rates was surprisingly small, but, from long-term measurements, a weak correlation was found among temperature, daily irradiance, and seasonal growth rate. The calculated species-specific primary production ranged from 0.5 to 1.8 mg C·m?2·day?1, about 1% of the estimated total production. Ceratium teres may be an important carbon source at the base of the grazing food chain. 相似文献
9.
K. Chandrasekhar A. Patricia Campbell Mei-Fen Jeng Arne Holmgren H. Jane Dyson 《Journal of biomolecular NMR》1994,4(3):411-432
Summary As a prelude to complete structure calculations of both the oxidized and reduced forms of Escherchia coli thioredoxin (Mr 11 700), we have analyzed the NMR data obtained for the two proteins under identical conditions. The complete aliphatic 13C assignments for both oxidized and reduced thioredoxin are reported. Correlations previously noted between 13C chemical shifts and secondary structure are confirmed in this work, and significant differences are observed in the C and C shifts between cis- and trans-proline, consistent with previous work that identifies this as a simple and unambiguous method of identifying cis-proline residues in proteins. Reduction of the disulfide bond in the active-site Cys32-Gly-Pro-Cys35 sequence causes changes in the 1H, 15N and 13C chemical shifts of residues close to the active site, some of them quite far distant in the amino acid sequence. Coupling constants, both backbone and side chain, show some differences between the two proteins, and the NOE connectivities and chemical shifts are consistent with small changes in the positions of several side chains, including the two tryptophan rings (Trp28 and Trp31). These results show that, consistent with the biochemical behavior of thioredoxin, there are minimal differences in backbone configuration between the oxidized and reduced forms of the protein. 相似文献
10.
The aim of this study was to characterize the electropharmacological effects of prostacyclin (PGI2) in human atrial fibers and cardiomyocytes. Atrial tissues obtained from the hearts of 28 patients undergoing corrective cardiac surgery were used. Transmembrane action potentials were recorded using a conventional microelectrode technique, and twitch force by a transducer. Effects of PGI2 (1 nM–10 µM) on action potential characteristics and contraction of atrial fibers were evaluated in normal [K]o (4 mM) and high [K]o (27 mM) in the absence and presence of cardiotonic agents. In addition, atrial and ventricular myocytes were isolated enzymatically from atrial tissues and hearts of 4 patients undergoing cardiac transplant. The effects of PGI2 on Na- and Ca-dependent inward currents (INa and ICa) of cardiomyocytes were tested. In 9 human atrial fibers showing fast-response action potentials (mean dV/dtmax = 101 ± 15 Vs–1) in 4 mM [K]o, PGI2 did not influence dV/dtmax of phase 0 depolarization even at 1 µM. However, at a concentration as low as 10 nM, PGI2 depressed spontaneous rhythms or slow-response action potentials in high-K-depolarized fibers. PGI2 also depressed delayed afterdepolarizations and aftercontractions induced by cardiotonic agents. In isolated cardiomyocytes, PGI2 reduced ICa but not INa. The present findings show that, in human atrial fibers and cardiomyocytes, PGI2 induces greater depressant effects on the slow-response action potential, ICa and triggered activity than on the fast-response action potential. It is suggested that PGI2 may act through a selective reduction of transmembrane Ca influx. 相似文献