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Pharmacological receptors for substance P and neurokinins 总被引:31,自引:0,他引:31
The three neurokinins identified in mammals, substance P, neurokinin A and neurokinin B, as well as their C-terminal biologically active fragments, have been used to characterize the responses of a variety of isolated organs. Three preparations selective either for substance P (the dog carotid artery), or for neurokinin A (the rabbit pulmonary artery) or for neurokinin B (the rat portal vein) are described. A neurokinin receptor classification is attempted using the neurokinins and their fragments to determine the order of potency of agonists. Three receptor subtypes have been identified: the NK-P, on which substance P (SP) is more active than neurokinin A (NKA) and neurokinin B (NKB), and the neurokinins are more active than their respective fragments; the NK-A on which NKA greater than NKB greater than SP, and some NKA fragments are more discriminative than their precursor; the NK-B on which NKB greater than NKA greater than SP, and fragments of NKB are less active than their precursor. Among the peptides studied, some potent compounds have been identified that could provide selective receptor ligands. 相似文献
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Chantal J. Beauchamp Patrice Dion Joseph W. Kloepper Hani Antoun 《Plant and Soil》1991,132(2):273-279
Thirty-two strains of opine-utilizing rhizobacteria were evaluated for physiological traits which have been related to plant growth-promoting activity. Tests included antibiosis against two bacterial and eight fungal pathogens of potato (Solanum tuberosum L.), production of hydrogen cyanide and fluorescent pigment production. On average, 71 and 12% of the bacteria inhibited the growth of Erwinia carotovora subsp. carotovora and Agrobacterium tumefaciens, respectively. The growth of Botrytis sp. was inhibited by 62% of the bacteria, and half of these produced an inhibition zone of more than 7 mm in diameter. Fusarium solani, Colletotrichum coccodes, Phoma exigua, Verticillium dahliae, F. oxysporum, V. albo-atrum and F. sambucinum were antagonized by 43, 34, 31, 25, 19, 18, and 12% of the bacteria, respectively. Only four strains produce hydrogen cyanide. The inhibition of a plant pathogen was not correlated to the production of fluorescent pigment. No strain produced a hypersensitive reaction whereas only three strains induced soft-rot and two produced polygalacturonase. Some opine-utilizing rhizobacteria were strong inhibitors of all plant pathogens, while most were active against specific plant pathogens. 相似文献
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Insertion of foreign DNA into the unique HindIII site of the high copy number plasmid pAT153 reduces but does not completely abolish the resistance of Escherichia coli HB101 cells to tetracycline. Recombinant DNA-containing colonies could then be phenotypically differentiated from non-recombinant ones by their smaller size on nutrient agar plates with ampicillin and tetracycline at a final concentration of 50 and 4 micrograms/ml, respectively. A wide variety of human cytomegalovirus DNA fragments have been found in pAT153 molecules propagated by the ampicillin-resistant tetracycline-sensitive bacteria selected. 相似文献
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Surfactant-associated glycoproteins A, 38 (A3), 32 (A2) and 26 (A1) kDa, pI (4.2-4.8), were identified as related proteins present in surfactant isolated from rat lung lavage fluid. Differences in size and charge among surfactant-associated glycoproteins A were related to differences in glycosylation as determined by reduction of the larger forms (38 and 32 kDa) to 26 kDa by endoglycosidase F and by increased isoelectric points of the glycosylated forms after treatment with neuraminidase. Synthesis and secretion of surfactant-associated glycoproteins A and precursors were demonstrated in purified rat Type II epithelial cells by immunoprecipitation of [35S]methionine-labelled proteins with anti-surfactant-associated glycoprotein A antisera. In pulse-chase experiments, labelled proteins 26-34 kDa, appeared within 10 min and smaller forms co-migrated with surfactant-associated glycoprotein A from alveolar lavage. The relative abundance of the larger molecular mass forms (30-34 kDa, pI 4.8) increased at later times up to 3 h. More acidic mature forms, which co-migrated with surfactant-associated glycoproteins A2 and A3 in surfactant (38 and 32 kDa), were readily detectable in the media, but were not abundant forms in lysates of labelled Type II cells after 1-3 h of incubation. Primary translation products of surfactant-associated glycoprotein A were immunoprecipitated with monospecific anti-surfactant-associated glycoprotein A antiserum after in vitro translation of poly(A)+ mRNA isolated from adult rat lung. The immunoprecipitated translation product migrated at 26 kDa, pI 4.8, and migrated slightly faster than surfactant-associated glycoprotein A1 from surfactant. Treatment of surfactant-associated glycoprotein A with bacterial collagenase resulted in proteolytic fragments 23-20 kDa, pI 4.2-4.8, which no longer underwent sulfhydryl-dependent cross-linking, suggesting that the collagen-like domain was required for the sulfhydryl-dependent oligomerization. Surfactant-associated glycoproteins A are synthesized by rat Type II epithelial cells as pre-proteins, 26-34 kDa. Larger forms result primarily from N-linked glycosylation of the 26 kDa primary translation product. Mature, more acidic forms result from further addition of sialic acid. 相似文献
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To determine whether glycopeptides could be released from glycoproteins bound to nitrocellulose, the glycoproteins of murine mammary tumor virus (MuMTV) were radiolabeled by the periodate oxidation/tritiated sodium borohydride reduction technique and separated by gel electrophoresis followed by diffusion transfer. Pronase digestion of nitrocellulose filter strips containing labeled glycoproteins (gp55 or gp34) revealed a rapid release of glycopeptides, i.e., approximately total release within 4 h. The released glycopeptides were similar in size, as determined by molecular sieving chromatography, to glycopeptides obtained by proteolytic digestion of MuMTV glycoproteins from dried gel strips (A. Zilberstein et al., 1980, Cell 21, 417-427) or in solution (M. J. Yagi et al., 1978, Virology 91, 291-304). 相似文献
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When the conditions for detecting proteins by ammoniacal silver staining (B. R. Oakley, D. R. Kirsch, and N. R. Morris (1980) Anal. Biochem. 105, 361-363.) following gel electrophoresis were varied, it was noted that glutaraldehyde pretreatment was necessary for maximal staining, which could not be explained simply as the result of "fixation." Further studies indicated that glutaraldehyde enhancement of protein staining with this silver reagent was probably due to oxidation of the aldehyde groups by silver ions, resulting in metallic silver depositions within the gel which act as nucleation sites for additional metallic silver localization in the protein bands upon the addition of formaldehyde developer. This proposed mechanism is consistent with the Tollen's reaction, as well as some aspects of the photographic process. Consistent with this notion, silver-staining intensities are directly related to mole percentage lysine of various standard proteins. 相似文献
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Influence of the route of administration on the pharmacokinetics of pirprofen enantiomers in the rat
The pharmacokinetics of the enantiomers of the non-steroidal anti-inflammatory drug pirprofen were studied in male Sprague-Dawley rats after oral and intravenous (iv) doses of the racemate. No significant differences were detected between the enantiomers after oral or iv dosing in t½, Vd, or ∑Xu. However, the R:S area under the plasma concentration (AUC) ratio after oral doses (0.92 ± 0.13) was slightly but significantly lower than after matching iv doses (1.05 ± 0.036). The absolute bioavailability of the active S-enantiomer (78.5%) after oral doses was higher than the inactive R-enantiomer (69.3%). The plasma protein binding of both enantiomers was saturable over a fivefold range of plasma concentrations. At higher plasma concentrations, the S-enantiomer was less bound than the R-enantiomer. In an in vitro experiment using everted rat jejunum, no chiral inversion was discernible. The dependency of the AUC ratio of the enantiomers on the route of administration may be due to stereoselective first-pass metabolism. © 1993 Wiley-Liss, Inc. 相似文献