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Lipoprotein-associated paf (LA-paf) was found in washed human platelets and monocyte/macrophage-like U937 cells 总被引:2,自引:0,他引:2
Ruth Korth Klaus Zimmermann Werner Oskar Richter 《Chemistry and physics of lipids》1994,70(2):109-119
Beyond cholesterol, inflammatory ether phospholipids such as platelet-activating factor (paf) may play a role in atherogenesis. (1) We detected a paf-like compound (‘LA-paf’) associated with human serum lipoproteins, mainly in LDL but not with the lipoprotein-poor fraction. (2) LA-paf was also found in washed human platelets, from where it was partially released during platelet aggregation in response to paf (50 nM) or thrombin (1 U). In addition, resident monocyte/macrophage-like U937 cells carried huge amounts of LA-paf (41 ng per 107 cells) and metabolized added [3H]paf to a labelled compound co-eluting with the retention time of LA-paf in standard HPLC. (3) Functionally, LA-paf had a comparable potency to synthetic paf, because LA-paf aggregated washed aspirin-treated platelets in a concentration-dependent manner. The specific paf receptor antagonist WEB2086 inhibited the platelet aggregation induced by three distinct LA-paf preparations as compared with synthetic paf with similar inhibitory concentrations (IC50: 35.6 ± 12.8, 24.0 ± 4.0, 38.0 ± 15.8 nM for LA-paf, and 43.6 ± 6.5 nM for synthetic paf), indicating that LA-paf interacted with paf receptors. (4) However, LA-paf had a distinct retention time using high-pressure liquid chromatography (HPLC) as compared with synthetic paf. LA-paf eluted at 9–15 min and synthetic paf at 21–24 min. In addition, total and non-specific [3H]paf binding to intact washed human platelets was affected differently by the two unlabelled agonists: while LA-paf increased total and non-specific (but not specific) binding in a significant manner (P < 0.002 and P < 0.007) as LDL did (P < 0.006 and P < 0.03), synthetic paf decreased total binding (P < 0.03). Similarly, low-density lipoproteins (LDL) increased significantly the total [3H]paf binding. In contrast, paf did not affect specific [125I]LDL binding to human fibroblasts. Our results show the presence of LA-paf in lipoproteins, 相似文献
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Fenge Christel Klein Cornelia Heuer Carsten Siegel Ursula Fraune Elisabeth 《Cytotechnology》1993,11(3):233-244
For an optimized bioreactor design which is adapted to the cultivation of sensitive animal cells different modular bioreactor components for gentle agitation, sufficient aeration and long-term perfusion were developed and investigated with respect to their suitability from laboratory to production scale. Aeration systems have been designed for both shear sensitive cells and cells which tolerate bubbles. The systems are based on either membranes for bubble-free aeration or stainless steel sparger systems. They were characterized by determination of their oxygen transfer capacity and optimized in cultivation processes of different cell lines under process conditions such as batch and perfusion mode.Different impellers for suspension cells and cells grown on carriers were investigated for their suitability to ensure homogeneous gentle mixing. A large pitch blade impeller as well as a novel 3-blade segment impeller are appropriate for homogeneous mixing at low shear rates. Especially with the 3-blade segment impeller fluid mechanical stress can be reduced at a given stirrer speed which is advantageous for the cultivation of cells attached to microcarriers or extremely shear sensitive suspension cells. However, our results indicate that shear sensitivity of animal cells has been generally overestimated.Continuous perfusion of both suspension cell cultures and cells cultivated on microcarriers could be successfully performed over extended periods of time using stainless steel spinfilters with appropriate pore sizes and systems based on microporous hydrophilic membranes. Spinfilters are suitable cell retention systems for technical scale bioreactors allowing continuous perfusion cultures of suspension cells (pore size 10 to 20 m) as well as anchorage dependent cells grown on microcarriers (pore size 75 m) over six weeks to 3 months.Applying the developed modules for agitation, aeration and perfusion process adapted bioreactor set-ups can be realized which ensure optimum growth and product formation conditions in order to maximize cell and product yields. 相似文献
16.
Carsten Bresch und Thomas Trautner 《Molecular & general genetics : MGG》1956,87(4):590-594
Summary Three different groups of mutations in bacteriophage are discussed with special reference to the coliphage T 1. One of these groups can be detected only by application of the Zweifarb-Nährboden. This technique, its advantages, and difficulties are described. Coloured photographs are shown of the most important genetic types of T 1 and of some heterozygotes which appear in genetic crosses.
Mit 6 Textabbildungen, davon 5 farbigen Teilfiguren 相似文献
Mit 6 Textabbildungen, davon 5 farbigen Teilfiguren 相似文献
17.
Madan K. Bhattacharyya Nancy L. Paiva Richard A. Dixon Kenneth L. Korth Bruce A. Stermer 《Plant molecular biology》1995,27(1):1-15
3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) catalyzes a key step in isoprenoid metabolism leading to a range of compounds that are important for the growth, development and health of the plant. We have isolated 7 classes of genomic clones encoding HMGR from a potato genomic library. Comparison of nucleic acid sequences reveals a high degree of identity between all seven classes of clones and the potato hmg 1 gene described by Choi et al. (Plant Cell 4: 1333, 1992), indicating that all are members of the same subfamily in potato. A representative member (hmg 1.2) of the most abundant class of genomic clones was selected for further characterization. Transgenic tobacco and potato containing the -glucuronidase (GUS) reporter gene under the control of the hmg 1.2 promoter expressed GUS activity constitutively at a low level in many plant tissues. High levels of GUS activity were observed only in the pollen. GUS assays of isolated pollen, correlations of GUS activity with the HMGR activity of anthers, hmg 1.2 promoter deletion studies, and segregation analysis of the expression of hmg 1.2::GUS among the R2 pollen of R1 progeny plants demonstrated that the hmg 1.2 promoter controls pollen expression. 相似文献
18.
Carsten Mei?ner Reinhold Deppisch Friederike Hug Matthias Schulze Eberhard Ritz Horst Ludwig Gertrud M. H?nsch 《Glycoconjugate journal》1995,12(5):632-638
Contact of mononuclear human leukocytes with cellulose dialysis membranes may result in complement-independent cell activation, i.e. enhanced synthesis of cytokines, prostaglandins and an increase in 2-microglobulin synthesis. Cellular contact activation is specifically inhibited by the monosaccharidel-fucose suggesting that dialysis membrane associatedl-fucose residues are involved in leukocyte activation. In this study we have detected and quantitatedl-fucose on commercially-available cellulose dialysis membranes using two approaches. A sensitive enzymatic fluorescence assay detectedl-fucose after acid hydrolysis of flat sheet membranes. Values ranged from 79.3±3.6 to 90.2±5.0 pmol cm–2 for Hemophan® or Cuprophan® respectively. Enzymatic cleavage of terminal -l-fucopyranoses with -l-fucosidase yielded 7.7±3.3 pmoll-fucose per cm2 for Cuprophan. Enzymatic hydrolysis of the synthetic polymer membranes AN-69 and PC-PE did not yield detectable amounts ofl-fucose. In a second approach, binding of the fucose specific lectins ofLotus tetragonolobus andUlex europaeus (UEAI) demonstrated the presence of biologically accessiblel-fucose on the surface of cellulose membranes. Specific binding was observed with Cuprophan®, and up to 2.6±0.3 pmoll-fucose per cm2 was calculated to be present from Langmuir-type adsorption isotherms. The data presented are in line with the hypothesis that surface-associatedl-fucose residues on cellulose dialysis membranes participate in leukocyte contact activation. 相似文献
19.
Expression of TRPC3 in Chinese Hamster Ovary Cells Results in Calcium-activated Cation Currents Not Related to Store Depletion 总被引:16,自引:0,他引:16 下载免费PDF全文
Christof Zitt Alexander G. Obukhov Carsten Strübing Andrea Zobel Frank Kalkbrenner Andreas Lückhoff Günter Schultz 《The Journal of cell biology》1997,138(6):1333-1341
TRPC3 (or Htrp3) is a human member of the trp family of Ca2+-permeable cation channels. Since expression of TRPC3 cDNA results in markedly enhanced Ca2+ influx in response to stimulation of membrane receptors linked to phospholipase C (Zhu, X., J. Meisheng, M. Peyton, G. Bouley, R. Hurst, E. Stefani, and L. Birnbaumer. 1996. Cell. 85:661–671), we tested whether TRPC3 might represent a Ca2+ entry pathway activated as a consequence of depletion of intracellular calcium stores. CHO cells expressing TRPC3 after intranuclear injection of cDNA coding for TRPC3 were identified by fluorescence from green fluorescent protein. Expression of TRPC3 produced cation currents with little selectivity for Ca2+ over Na+. These currents were constitutively active, not enhanced by depletion of calcium stores with inositol-1,4,5-trisphosphate or thapsigargin, and attenuated by strong intracellular Ca2+ buffering. Ionomycin led to profound increases of currents, but this effect was strictly dependent on the presence of extracellular Ca2+. Likewise, infusion of Ca2+ into cell through the patch pipette increased TRPC3 currents. Therefore, TRPC3 is stimulated by a Ca2+-dependent mechanism. Studies on TRPC3 in inside-out patches showed cation-selective channels with 60-pS conductance and short (<2 ms) mean open times. Application of ionomycin to cells increased channel activity in cell-attached patches. Increasing the Ca2+ concentration on the cytosolic side of inside-out patches (from 0 to 1 and 30 μM), however, failed to stimulate channel activity, even in the presence of calmodulin (0.2 μM). We conclude that TRPC3 codes for a Ca2+-permeable channel that supports Ca2+-induced Ca2+-entry but should not be considered store operated. 相似文献
20.
From the Namurian B of the Bergisches Land the oldest known remain of the Dictyoneuridae is described, namedSchmidtopteron adictyon n. g., n. sp. Present is a wing with the following characteristics: 1. shape long and slender; 2. subcosta relativly short; 3. radius nearly as long as the wing; 4. radius-sector branched off from the radius at 1/5 of the length of the wing (prox.), subdivided into 4 branches; 5. medialis subdivided also at 1/5 of the length of the wing; MEp with 2 branches; 6. cubitus subdivided at 1/10 of the length of the wing, CUp undivided; 7. anal veins 4 in number, separated each from the others in full length; at least A1 und A2 bifurcated; 8. A1 and CUp joined by a short connecting vein; 9. archaeodictyon not present. Schmidtopteron adictyon is the most primitive Namurian wing known. Its systematic position results from the structure of the only little branched veins. The absence of the archaeodictyon may be attributed to preservation: only the external mould of the upper surface of the wing is preserved. From all other genera of the Dictyoneuridae,Schmidtopteron is separated by the connection between A1 and CUp. This feature, and the relative large anal area, show thatSchmidtopteron is not the ancestor of younger Dictyoneuridae, but an early side branch of the evolution of this family. 相似文献