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81.
Triphosphoinositide breakdown and dense body release as the earliest events in thrombin-induced activation of human platelets 总被引:2,自引:0,他引:2
F Rendu P Marche J Maclouf A Girard S Levy-Toledano 《Biochemical and biophysical research communications》1983,116(2):513-519
The activation by thrombin of human platelets prelabelled with 32P induced a 30-40% decrease in 32P-triphosphoinositides (TPI) in the first 10 sec; the decrease in the other 32P-labelled phosphoinositides occurred by 20-30 sec. At 10 sec., the intensity of these effects was maximum with 0.2-0.4 U/ml thrombin. Under these conditions, 53, 20 and 15% of the dense granule, alpha-granule and lysosome constituents, respectively were released and thromboxane B2 synthesis reached only 10% of its maximum. Together with experiments carried out with chlorpromazine - or PGE1 - treated platelets, our results suggest the existence of a close relationship between TPI-breakdown and dense body release which appear to be the earliest events resulting from the activation of human platelets by thrombin. 相似文献
82.
M Solti P Dévay I Kiss J Londesborough P Friedrich 《Biochemical and biophysical research communications》1983,111(2):652-658
Like adult heads and whole flies, larval brains of wild type Drosophila melanogaster contain two major soluble cyclic nucleotide phosphodiesterases, forms I and II. Larval brains of the learning-defective mutant strain, dunceM11, contain only the form I enzyme. In both wild type and dunce strains the form I enzyme is activated by Ca2+/calmodulin. A time-dependent loss of this Ca2+ activation was observed. 相似文献
83.
L Kurlansik T J Williams J E Campana B N Green L W Anderson J M Strong 《Biochemical and biophysical research communications》1983,111(2):478-483
In addition to dimerization and polymerization of samples as previously suggested, it appears that during FAB-MS, reactions in the sample matrix can occur to yield new compounds that are recombinations of molecular fragments. This type of reaction may be especially critical to the integrity of peptide sequencing using FAB, since the reactions cited in this report involve the formation and rupture of amides or peptide bonds. 相似文献
84.
Chemotactic factor causes rapid decreases in phosphatidylinositol,4,5-bisphosphate and phosphatidylinositol 4-monophosphate in rabbit neutrophils 总被引:20,自引:0,他引:20
M Volpi R Yassin P H Naccache R I Sha'afi 《Biochemical and biophysical research communications》1983,112(3):957-964
Stimulation of rabbit neutrophils prelabeled with 32P by the synthetic chemotactic peptide f-Met-Leu-Phe induces a rapid decrease in the radioactivity in both phosphatidylinositol, 4,5 bis phosphate and phosphatidylinositol 4-monophosphate. The mean +/- standard error of the mean values of the maximum decrease in phosphatidylinositol, 4,5 bis phosphate occurred at 10 seconds following stimulation and is equal to 19 +/- 3% of the control value. The corresponding value for phosphatidylinositol 4-monophosphate occurred at 60 seconds following stimulation and is equal to 37 +/- 7% of the control value. On the other hand, the radioactivity in phosphatidic acid and lysophospholipids increased continuously with time following stimulation. The relationship of these changes to calcium release and neutrophil activation is discussed. 相似文献
85.
Adenosine deaminase normalizes cyclic AMP responses of hypothyroid rat fat cells to forskolin, but not beta-adrenergic agonists 总被引:2,自引:0,他引:2
Lipolysis and cyclic AMP accumulation in response to beta-adrenergic agonists or forskolin are severely impaired in fat cells from the hypothyroid rat. Incubating hypothyroid rat fat cells with adenosine deaminase normalizes the cyclic AMP response to forskolin, but not to beta-adrenergic agonists. Increased sensitivity to adenosine action in the hypothyroid state appears to be the basis for the impaired cyclic AMP response to forskolin, but does not appear to be the underlying defect responsible for the impaired response to beta-adrenergic agonists. 相似文献
86.
Adult sockeye salmon, Oncorhynchus nerka (Walbaum), treated with salmon pituitary extract in July survived for up to 47 days and developed nuptial colours in both male and female fish during this period, whereas no such characteristics appeared in untreated control fish. Furthermore, results showed that 20 of 50 adult female Philomena oncorhynchi recovered from the 15 treated fish contained fully developed tailed larvae in the uterus as compared with only one of 44 female P. oncorhynchi from 31 untreated control fish. None of 51 worms from 13 stilboestrol treated adult sockeye showed development in utero beyond an elongated embryo, nor did the host fish develop nuptial colours. P. oncorhynchi and its immature sockeye host (approx. 1 year prior to spawning) remained unaffected by any of three separate hormone treatment experiments using injection of salmon pituitary extract, injection of 17-β-estradiol, and stilboestrol mixed in the food. 相似文献
87.
Calcium-dependent activation and deactivation of rod outer segment phosphodiesterase is calmodulin-independent 总被引:2,自引:0,他引:2
ATP-dependent activation and deactivation of retinal rod outer segment phosphodiesterase is affected by calcium [Kawamura, S. and Bownds, M. D., J. Gen. Physiol. 77:571-591(1981)]. Our data demonstrate that although calmodulin has been found in rod outer segments [Liu, Y. P. and Schwartz, H., Biochim. Biophys. Acta 526:186-193(1978); Kohnken, R. E. et al, J. Biol. Chem. 256:12517-12522(1981)], this protein is not involved in calcium-dependent phosphodiesterase activation at light levels at which calcium clearly affects this enzyme's activity. Furthermore, calmodulin does not mediate the calcium-dependent deactivation of phosphodiesterase. 相似文献
88.
Disassembly of microtubules by the action of calmodulin-dependent protein kinase (Kinase II) which occurs only in the brain tissues 总被引:8,自引:0,他引:8
Microtubules assembled by the incubation of GTP at 37 °C were disassembled by the action of calmodulin-dependent protein kinase (Kinase II) which occrs only in the brain tissues. This disassembly required the presence of ATP and physiological concentrations of Ca2+ and calmodulin. 相似文献
89.
Thyroid Hormones and Derivatives Inhibit Flunitrazepam Binding 总被引:1,自引:1,他引:0
Thyroid hormones and their derivatives were found to inhibit [3H]flunitrazepam binding stereospecifically and in a monophasic manner. Among the compounds tested, D-thyroxine was the most potent inhibitor (IC50 = 0.5 microM). The naturally occurring L-thyroxine was about 40-fold less potent (IC50 = 20 microM). The structure-activity relationships seem to imply that the thyronine base has the principal role in the inhibition of benzodiazepine receptor binding. The type of inhibition was examined with the most potent inhibitor, D-thyroxine, by Scatchard analysis. The apparent dissociation constant (KD) of the [3H]flunitrazepam binding increased and the receptor density (Bmax) decreased as a function of D-thyroxine concentration; this is characteristic of mixed-type inhibition. 相似文献
90.
Abstract: Recently, it was proposed that β-carbolines interact with a subset of benzodiazepine (BZD) binding sites in mouse brain. This postulate was based upon evidence showing changes in binding properties of the BZD receptor following photoaffinity labeling of membranes with flunitrazepam (FLU). Under conditions in which 80% of specific [3H]diazepam binding was lost in photolabeled membranes, specific [3H]propyl β-carboline-3-carboxylate ([3H]PCC) binding was spared. In this study, the binding of the BZD antagonists [3H]PCC, [3H]Ro15 1788 and [3H]CGS 8216 was examined in rat brain membranes following photoaffinity labeling with FLU. No significant changes in the apparent KD and small reductions in the Bmax of 3H antagonist binding were observed. However, in the same membranes, up to 89% of specific [3H]FLU binding was lost. When [3H]PCC (0.05 nM) was used to label the receptors in control and photolabeled membranes, the ability of BZD receptor agonists to inhibit [3H]PCC binding was greatly diminished in the photolabeled membranes. In contrast, the potency of BZD antagonists remained the same in both control and treated membranes. Based upon PCC/[3H]Ro15 1788 competition experiments, the ability of PCC to discriminate between BZD receptor subtypes was unaffected by photoaffinity labeling of cortical membranes. Overall, these findings suggest that β-carbolines do not interact with a subset of BZD binding sites per se, but may be a consequence of the differential interaction of BZD agonists and antagonists with BZD binding sites that have been photoaffinity labeled with FLU. A possible mechanism underlying this phenomenon is discussed. The ability of photolabeled membranes to differentiate between BZD agonists and antagonists provides a potential screen for agonist and antagonist activity in compounds that interact with the BZD receptor. 相似文献