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1.
immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma 总被引:1,自引:0,他引:1 下载免费PDF全文
L Skriver LI Larsson V Kielberg LS Nielsen PB Andresen P Kristensen K Dano 《The Journal of cell biology》1984,99(2):753-758
The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA. 相似文献
2.
The diffusion behavior of DNA samples of molecular weights between 1 × 106 and 25 × 106 Daltons was investigated under standard conditions at mean concentrations c? between 0.0009 and 0.017 g/dl. Special techniques described previously were used and supplemented. The sensitivity required was accomplished by multiple passage through the sample cells (effective path length of 10–45 cm) and application of the Gouy interference method. The maximum DNA refraction index difference has been determined more precisely from Gouy interference fringes by applying a systematic variation procedure and a linear-plot criterion. Convection was prevented by a temperature constancy better than 0.002°C/day, vibrationless operation, and by application of a slight density gradient of heavy water, which also improved the boundary-forming procedure. The corresponding optical HDO gradient was compensated. The concentration dependence of the DNA diffusion coefficient average DA was found to be positive and very small at extremely low concentrations, that is, below c? = 0.008 g/dl, for the sample of highest molecular weight investigated. With beginning penetration of different DNA molecules, DA increases markedly. The diffusion constant averages of our polydisperse samples will be corrected for monodisperse subfractions in a following paper. The resulting molecular weights M from diffusion and sedimentation constants (D0, s0) together with data from literature are the basis of new s0–M, D0 ? M, and [η]–M relations for monodisperse DNA samples. 相似文献
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4.
Interaction of the oligopeptide antibiotics netropsin and distamycin A with nucleic acids 总被引:19,自引:0,他引:19
C Zimmer K E Reinert G Luck U W?hnert G L?ber H Thrum 《Journal of molecular biology》1971,58(1):329-348
5.
Protoplasten aus Zellkulturen vonDaucus carota 总被引:1,自引:1,他引:0
Summary Treatment of long-term tissue cultures of carrots and of adventive embryos in these cultures with Cellulase Onozuka P 1500 and with this enzyme + Macerocym resulted in high yields of protoplasts which could be cultivated over prolonged periods (up to 5 months) in a synthetic medium + 0.6 m sorbitol. During cultivation the size of the protoplasts increased considerably ( up to 10 times) and a high percentage of multinucleate (between 2 and 13 nuclei) protoplasts were formed. However no fusion and no regeneration of cell walls were observed. 相似文献
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Streptokinase mutations relieving Escherichia coli K-12 (prlA4) of detriments caused by the wild-type skc gene 总被引:2,自引:2,他引:0 下载免费PDF全文
A novel phenotype is described for Escherichia coli K-12 carrying the prlA4 allele determining a membrane component of the protein export mechanism. It is manifest as transformation deficiency for plasmids containing the cloned group C streptococcal streptokinase gene, skc. Streptokinase plasmid mutations relieving the prlA4 strain of this deficiency fell into three classes. Class 1 included skc::IS5 insertions, with IS5 integrated in a region encoding the Skc signal sequence and inactivating skc. Class 2 included IS1 insertions leaving skc intact but reducing skc expression, presumably by altering the function of the skc promoter as judged by an insertion site close to the -35 region. The most interesting class, 3, included skc deletions removing the entire signal sequence or a tetrapeptide from its hydrophobic core. The tetrapeptide deletion reduced the size, hydrophobicity, and predicted alpha-helicity of the central region of the Skc signal sequence but facilitated the export of mature Skc in both the wild type and the prlA4 mutant. These findings indicate that the incompatibility between prlA4 and skc is related to deleterious effects of the Skc signal sequence. The tetrapeptide deletion may function by altering the conformation of the signal sequence so as to render interaction with both the PrlA wild-type protein and the PrlA4 mutant protein less detrimental to the export mechanism. These findings also provide an explanation for the difficulties encountered in cloning streptokinase genes in E. coli plasmids and maintaining their structural stability. 相似文献
8.
J Hoffmann C Westendorff D Troitzsch U Ernemann S Reinert 《Biomedizinische Technik》2004,49(7-8):199-201
Laser-induced interstitial thermal therapy (LITT) is a proven minimally invasive surgical technique for the treatment of haemangiomas and vascular malformations, and various tumours. The intra-lesion application of thermal energy destroys regional tissue. The percutaneous placement of the laser fibre for photocoagulation is done without the benefit of direct visual control. Image-data-based LITT was performed in patients (five procedures) with extensive venous malformations in the maxillofacial area. The system comprised a specially developed Nd:YAG laser fibre introducer set used in conjunction with fused high-resolution computed tomography, and magnetic resonance image-data--based surgical navigation. In all cases, follow-up examination clearly showed a diminishment in tumour volume, and all patients reported significant subjective improvement. The results suggest that navigation-guided LITT can be performed safely, preserving vital structures from collateral thermal damage. 相似文献
9.
Summary Carrot cells in suspension culture were incubated during the log-phase of the culture transfer cycle for different periods with one of the following precursors of nucleic acid synthesis: [32P]-orthophosphate, [5,6-3H]-uridine, and [2-14C]-uridine. Cells were gently broken by a short period of sonication, and the total RNA of the cells was extracted by a phenoldetergent method at pH 9.0. Subsequently, crude RNA was purified from contaminating substances like carbohydrates and nucleotides, and the pure RNA preparations were characterized by MAK-chromatography and constant velocity sedimentation in isokinetic sucrose gradients.Rapidly-labelled RNA-fractions were detected in the radioactive profiles obtained with both separation methods. These RNA-fractions showed a high specific incorporation rate, but almost no detectable UV-absorbance,i.e., they are RNA species with a high turnover rate and represent only a small part of the total RNA of the cell. With increasing periods of labelling and in a series of pulse-chase experiments high molecular weight RNA-fractions released by high-salt washing of MAK-columns exhibited a shift of the incorporated radioactivity from fractions with higher to those of lower molecular weights. Furthermore, in sucrose gradients a similar shift was observed for RNA-fractions with estimated sedimentation coefficients of 50 S, 40 S, 34 S and 22 S; the radioactivity was converted from these high to the low S-values of the 26 S and 18 S rRNAs, respectively. This parallel in the behaviour of the high molecular weight RNA-fractions from both separation methods indicates their putative role as precursors of rRNA-synthesis. Moreover, there is evidence that the high molecular weight RNA-fractions from the MAK-columns which were eluted after the 26 S rRNA consist not only of the precursors of rRNAs, but also of polydisperse RNA-fractions with S-values smaller than 18 S. These probably contain fractions of HnRNA and mRNA. 相似文献
10.
This paper simulates the helix-characteristic changes of apparent DNA persistence length caused by randomly distributed helix bends as induced, e.g., by DNA-bound ligand molecules. The parameters varied are the constant angle gamma of helix bending and the size alpha of the DNA drug binding site, but also the degree of DNA-ligand binding cooperativity and the helix-unwinding angle. If the size of the binding site is comparable with the helix pitch, the influence of phasing between helix bends and helix screw upon the apparent persistence length is obvious. In the accompanying paper experimental data are analyzed in terms of this theoretical background. 相似文献