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261.
Purification and partial characterization of multiple bromoperoxidases from Streptomyces griseus 总被引:1,自引:0,他引:1
The presence of multiple bromoperoxidases in extracts of Streptomyces griseus Tü 6 was detected. The enzyme pattern varied with the age of the culture. A haem-type bromoperoxidase (BPO 2) was always present. Additionally three nonhaem-type bromoperoxidases (BPO 1a, 1b and 3) were detected and purified to homogeneity. The Mr of non-denatured BPO 1a was 70,000 +/- 10,000 and those of BPO 1b and 3 were 90,000 +/- 5000. BPO 1a and 1b were dimers with subunit Mr values of 34,000 and 43,000, respectively. BPO 3 was a trimer with a subunit Mr of 31,000. The enzymes differed in their isoelectric points, heat stability, and Km values. In immunodiffusion experiments BPO 1a and 3 showed partial identity with the nonhaem-type bromoperoxidase from Streptomyces aureofaciens. The nonhaem-type BPO 1a, 1b and 3 had neither peroxidase nor catalase activity. 相似文献
262.
J Van Damme J Van Beeumen B Decock J Van Snick M De Ley A Billiau 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(5):1534-1541
Supernatants of mitogen-stimulated human leukocytes contain two biologically related cytokines, IL-1 and hybridoma growth factor (HGF). IL-1 beta is a potent inducer of HGF in fibroblasts but has little stimulating effect on monocytes that spontaneously produce HGF. Leukocyte-derived HGF and IL-1 were separated by the use of affinity chromatography on specific antibodies and discriminating assay systems for both cytokines. They had different Mr upon gel filtration and SDS-PAGE. In contrast to IL-1 beta, HGF showed heterogeneity on a cation-exchange column. IL-1 beta and HGF were purified to homogeneity by a sequence of four and five purification steps, respectively. Leukocyte-derived HGF was characterized by analysis of its NH2-terminal amino acid sequence. This revealed complete homology with fibroblast-derived HGF, 26-kDa protein, IFN-beta 2, and B cell stimulatory factor 2, molecules which have collectively been designated as IL-6. IL-1 beta exerted an antiviral and growth-promoting effect of fibroblasts, whereas HGF/IL-6 did not. Both IL-1 and IL-6 possessed lymphocyte-activating factor activity, which could be neutralized only by an anti-serum against the corresponding cytokine. 相似文献
263.
M M Mulder H M Van der Gulden P W Postma K Van Dam 《Journal of general microbiology》1988,134(3):777-783
The steady-state bacterial dry wt of Escherichia coli, growing under K+-limited conditions in the chemostat, was inversely dependent on the growth rate. This phenomenon was more carefully investigated in medium-flow stop experiments. Growth did not stop immediately but continued for a time, initially at the same rate as before. The dry wt increased to a value corresponding to a steady-state growth rate near zero, independent of the initial specific growth rate. This was observed in both the wild-type strain and a mutant that lacked the high-affinity K+ uptake system. The wild-type strain maintained a low extracellular K+ concentration both in the chemostat under steady-state conditions and after stopping the medium flow. The mutant, on the other hand, maintained a much higher extracellular K+ concentration in the steady state, which decreased to much lower values after stopping the medium flow. From the increase in bacterial dry wt and the low external K+ concentration after stopping the medium flow it is concluded that the intracellular K+ is redistributed among the cells, including new cells. The growth yield on K+ was highest in the stationary growth phase of a batch culture and all steady-state cultures converged ultimately to this yield value after the medium flow had been stopped. It is proposed that the growth rate of E. coli under K+-limited conditions is determined by the intracellular K+ concentration. 相似文献
264.
Sensitive detection of immunogold-silver staining with darkfield and epi-polarization microscopy 总被引:3,自引:0,他引:3
M De Waele W Renmans E Segers K Jochmans B Van Camp 《The journal of histochemistry and cytochemistry》1988,36(6):679-683
We evaluated the contribution of darkfield and epi-polarization microscopy to the detection of leukocyte cell surface antigens with immunogold-silver staining (IGSS). Lymphocyte cell surface differentiation antigens were labeled with monoclonal antibodies and IGSS as described for brightfield microscopy. In darkfield and epi-polarization microscopy the labeling appeared as bright spots on a dark background. The sensitivity of detection was much higher than that of brightfield microscopy. Sixteenfold higher dilutions of the monoclonal antibody could be used to detect all cells expressing the antigen in the cell suspension. However, non-specific staining was also better visualized. The latter could be reduced to a level comparable to that of brightfield microscopy only by use of weaker labeling conditions. A 25% reduction of the silver enhancement time was necessary for this purpose. However, these weaker labeling conditions also reduced the intensity of the specific staining. Therefore, the efficiency of IGSS, as detected with darkfield and epi-polarization microscopy, was only fourfold greater than that found with brightfield microscopy or that of an immunofluorescence procedure. Especially in combination with transmitted light, to improve cell identification, epi-polarization microscopy is a reliable and sensitive method for detection of immunogold-silver-labeled cell surface antigens for diagnostic and research purposes. 相似文献
265.
Aromatic L-amino acid decarboxylase (AADC) catalyzes the cellular decarboxylation of L-aromatic amino acids and is therefore involved in the synthesis of several biogenic amines. Application of the indirect immunoperoxidase method on human, rat, and mouse tissues using specific antibodies to AADC revealed all AADC-containing cells. Besides mast cells and adrenergic nerve fibers, the following cells were immunostained: neuroendocrine cells in the tracheobronchial epithelium; neuroepithelial bodies in the bronchopulmonary epithelium; Kultschitzky cells in the small intestine and appendix as well as adrenal chromaffin cells. All the latter cells belong to the so-called APUD system, the "D" in the acronym standing for the activity of the enzyme aromatic L-amino acid decarboxylase. Immunocytochemistry for AADC may become an additional tool not only to highlight APUD cells in tissue sections but also to differentiate the sites of cellular amine synthesis from those of amine storage. 相似文献
266.
Modification of the Recalde method for the isolation of human monocytes 总被引:23,自引:0,他引:23
A M Fogelman F Elahi K Sykes B J Van Lenten M C Territo J A Berliner 《Journal of lipid research》1988,29(9):1243-1247
A modification of the method for monocyte isolation reported by Recalde (1984. J. Immunol. Methods. 69: 71-77) is described. Application of the modified method to 36 consecutive healthy adult donors gave a monocyte purity of 73 +/- 8% monocytes with less than 1% polymorphonuclear leukocytes and a yield of 3.44 +/- 0.93 x 10(5) monocytes/ml blood. While the monocyte purity of the modified Recalde method was lower than that obtained by elutriation (method BB in Fogelman et al. 1981. J. Lipid Res. 22: 1131-1141) in 15 donors (71 +/- 10% vs. 83 +/- 6%) the monocyte yield and the viability of the cells before and after culture were similar in both methods. The modified Recalde method does not require the expensive or complicated equipment required for elutriation and permits the isolation of human monocytes for culture in autologous serum from multiple donors in a single day. 相似文献
267.
The ovary of Xiphinema theresiae is studied ultrastructurally. It consists of two cell types, the ovarian epithelial cells and the germ cells. The ovarian epithelial cells form a thin layer around the germ cells. Their nuclei are located in between the germ cells. At some sites, processes of the ovarian epithelial cells migrate inward and form a central cytoplasmic mass. The germ cells have a large lobated nucleus, with an eccentric nucleolus, and are considered to represent young previtellogenic oocytes. In contact with the central cytoplasmic mass, the germ cells develop two membrane derived features, the villi and the small coated bulges, which most probably play a role in transport. 相似文献
268.
A continuous noncontact method for measuring in situ vascular diameter with a video camera 总被引:1,自引:0,他引:1
Bell L. B.; Hopp F. A.; Seagard J. L.; Van Brederode H. F.; Kampine J. P. 《Journal of applied physiology》1988,64(3):1279-1284
A new, continuous, on-line, video diameter-measuring technique, utilizing a video camera mounted on the sidearm of a stereo microscope, is described. Vessel diameter is derived from changes in the video output signal of the camera or a video recorder when the vessel of interest is displayed horizontally on a monitor and well contrasted with its background. A comparator threshold is set on the filtered video output signal and generates an output pulse that is used to gate horizontal video sync pulses to a digital counter-timer. The number of pulses counted for each video field (no. of horizontal video lines) is proportional to the vessel diameter. The video-derived diameter is calibrated using known standards and correlates well with sonomicrometer-derived diameters of the carotid artery and jugular vein during increasing pressure ramps (r greater than 0.999). The diameter update rate is 60 Hz, and the resolution of the system is one horizontal video line, independent of the vessel size. With suitable magnification and contrast both arteries and veins as small as 200 micron have been measured using this system. 相似文献
269.
Independent carrot (Daucus carota) hairy root lines were established by inoculation of discs taken from the same carrot with Agrobacterium rhizogenes 8196 and A. tumefaciens C58C1(pRi8196) carrying pRi8196. Several lines were compared with respect to T-DNA length. One of them was found to have integrated sequences covering more than 50 kbp of the Ri plasmid 相似文献
270.
M Capron M Tomassini E Van der Vorst J P Kusnierz J P Papin A Capron 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1988,307(7):397-402
The existence of receptors for immunoglobulin A on human eosinophils is demonstrated by flow cytofluorometry. Between 5 and 60% of eosinophils purified from peripheral blood of hypereosinophilic patients are able to bind monomeric serum IgA. The addition of antihuman IgA antibodies to surface IgA-bearing eosinophils induces the exocytosis of peroxidase contained in the granules suggesting a cell activation due to IgA receptors. The inhibition of antiparasitic cytotoxicity by eosinophils preincubated with IgA under a polymeric form only, indicates the low affinity of IgA receptors as well as their participation in the effector function of eosinophils. 相似文献