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1.
Activation of the mitogen-activated protein (MAP) kinase pathway has been associated with both cell proliferation and differentiation. Constitutively activated forms of Mek (MAP kinase/Erk kinase) and Erk (MAP kinase) have been previously shown capable of inducing differentiation or proliferation in nonhematopoietic cells. To specifically examine the role of Erk activation in megakaryocytic growth and development, we activated the MAP kinase pathway by the transfection of constitutively activated Mek or Erk cDNA into a human megakaryoblastic cell line, CMK, by electroporation. The CMK transfectant clones that expressed constitutively activated Mek or Erk showed morphologic changes of differentiation. Transfected cells also showed expression of mature megakaryocytic cell surface markers. The MAP kinase pathway was also activated by treatment of the hematopoietic cells with a cytokine that activates Erk. The treatment of CMK cells with stem cell factor (SCF ) caused MAP kinase activation and induced differentiation by the expression of mature megakaryocytic cell surface markers. The effects of the SCF treatment were inhibited by pretreatment with a specific inhibitor of the MAP kinase pathway, PD98059. In this report, we conclude that activation of the MAP kinase pathway was both necessary and sufficient to induce differentiation in this megakaryoblastic cell line. 相似文献
2.
JF Delaloye S Leyvraz E Outcha Adjahoto J Bauer P De Grandi 《Canadian Metallurgical Quarterly》1996,19(2):204-206
We report two cases of metastatic non-functioning pancreatic endocrine tumour with very elevated plasma levels of alpha-fetoprotein. In these two cases, serial plasma levels of alpha-fetoprotein, initially normal, correlated well with hepatic tumour progression and were associated with fatal outcome. These results suggest that elevated plasma concentration of alpha-fetoprotein may be caused by metastatic pancreatic endocrine tumour and than alpha-fetoprotein serial measurement may be useful in prognostic evaluation. 相似文献
3.
Patients with ulcerative colitis are usually non- or ex-smokers in contrast to Crohn's disease where smoking is common. Abnormalities of quantity and quality of intestinal mucus have been postulated in the pathogenesis of these diseases. It is possible that smoking habit may exert its effects via changes in mucus in inflammatory bowel disease. We have therefore studied incorporation of N-acetylglucosamine into synthesized colonic mucin in explants from 85 controls with normal colonoscopic appearances and histology, including 27 smokers and 58 nonsmokers, 36 patients with ulcerative colitis and 19 with ileocolonic Crohn's disease over 24 h in tissue culture. Incorporation of N-acetylglucosamine into normal explants was 31.3 +/- (SD) 7.1 dpm/microgram biopsy protein, incorporation was increased in patients with active Crohn's disease (mean 41.2 +/- (SD) 10.4 dpm/microgram biopsy protein, p = 0.003), decreased in inactive ulcerative colitis (mean 24.1 +/- 7.8 dpm/microgram biopsy protein, p = 0.0006) but normal in active ulcerative colitis (mean 35.0 +/- 13.8 dpm/microgram biopsy protein, p = 0.44). No significant relationship was found between cigarette smoking habits and mucus synthesis in controls with normal mucosa (nonsmokers, n = 58, mean 31.0 +/- (SD) 7.52 dpm/microgram biopsy protein; smokers, n = 27, mean 31.8 +/- (SD) 6.1 dpm/microgram biopsy protein, p = 0.9). This study shows that mucus glycoprotein synthesis is reduced in inactive ulcerative colitis, rising to normal levels in active disease and that synthesis is increased in Crohn's disease. There is no effect of smoking on mucus synthesis by control biopsies suggesting that the differences seen in inflammatory bowel disease are not related to cigarette smoking. 相似文献
4.
We have designed a family of parallel data flow analysis algorithms for execution on distributed-memory MIMD machines, based on general-purpose, hybrid algorithms for data flow analysis [Marlowe and Ryder 1990]. We exploit a natural partitioning of the hybrid algorithms and explore a static mapping, dynamic scheduling strategy. Alternative mapping-scheduling choices and refinements of the flow graph condensation used are discussed. Our parallel hybrid algorithm family is illustrated on Reaching Definitions, although parallel algorithms also exist for many interprocedural (e.g., Aliasing) and intraprocedural (e.g., Available Expressions) problems [Marlowe 1989]. We have implemented the parallel hybrid algorithm for Reaching Definitions on an Intel iPSC/2. Our empirical results suggest the practicality of parallel hybrid algorithms.An earlier version of this paper was presented at Supercomputing '90.The research reported here was supported, in part, by the New Jersey Commission on Science and Technology and the CAIP Center's Industrial Members, by Siemens Research Corporation and by National Science Foundation grant CCR-8920078. 相似文献
5.
6.
Numerous investigators have suggested that cell glycoconjugates are modified by the development of cancer and the progression of this to a malignant form. Accordingly, in the present work, beta-D-galactosidase, alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities were studied in human thyroid and gastric tumours. Samples were obtained from human gastric mucosa and thyroid gland tumours together with a part of the surrounding normal tissue (control). Enzyme activity was determined spectrophotometrically based on the release of p-nitrophenol from suitable p-nitrophenyl-derivative substrates. Results showed that beta-D-galactosidase, alpha-L-fucosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities were detected in tumour and control samples from thyroid and gastric tissues. The gastric mucosa also showed alpha-L-mannosidase activity. The specific activities of these glycosidases were higher (two- or three-fold) in tumour tissues as compared with their controls. beta-D-galactosidase, beta-N-acetyl-D-glucosaminidase and beta-N-acetyl-D-galactosaminidase activities from thyroid and gastric tumours showed a significant increase in V(max) as compared with their respective controls (P < 0.05 or P < 0.001). Thyroid alpha-L-fucosidase activity showed a statistically and significantly increased affinity (lower K(m)) in tumour samples as compared to normal tissue. In conclusion both gastric and thyroid tumours showed enhanced glycosidase activity as compared with enzyme activity observed in normal tissue. These results are in agreement with the notion of a markedly raised degradation within lysosomes of tumour cells. 相似文献
7.
Interactions of metals and protons with algae 总被引:2,自引:0,他引:2
Crist RH Oberholser K Schwartz D Marzoff J Ryder D Crist DR 《Environmental science & technology》1988,22(7):755-760
8.
Synthesis and Microstructure of Highly Oriented Lead Titanate Thin Films Prepared by a Sol-Gel Method 总被引:1,自引:0,他引:1
Chiahong Chen Daniel F. Ryder Jr. William A. Spurgeon 《Journal of the American Ceramic Society》1989,72(8):1495-1498
Thin films of PbTiO3 were deposited on fused silica, resistor-grade alumina, and single-crystal (100) MgO by a sol–gel processing method. Whereas the films deposited on silica and alumina substrates were randomly oriented and polycrystalline, highly {100} oriented PbTiO3 films were grown on the MgO single crystals. The perovskite-type structure was observed with films deposited on the single-crystal MgO and annealed at temperatures as low as 470°C, whereas a pyrochlore-type strcuture was observed with films on fused silica and alumina processed in a similar manner. All films heat-treated at temperatures in excess of 570°C showed significant formation of a second PbTi3 O7 phase. The films were characterized by electron microscopy and glancing-incidence-angle X-ray diffraction. 相似文献
9.
The amount and composition of the nonvolatile residue in solvent hexane are important quality criteria. These residue characteristics
are particularly significant in the hexane extraction of foods because of the possibility of contaminating edible products.
A laboratory evaluation of the residue from a typical hexane was made to find if there was any trace of multi-ring aromatics
which might be potential carcinogens.
Samples of hexane directly from a refinery and after storage and transportation to two solvent extraction plants were analyzed.
All residues were separated by paper chromatography and analyzed by ultraviolet spectrophotometry. In no case, were they found
to contain polynuclear aromatic carcinogenic materials. The test method is sensitive to less than 0.01 ppm.
In order to verify the accuracy of the test, an analysis was made for the quantitative recovery of a known carcinogen. For
this purpose, 0.01 ppm of 3,4 benzpyrene was added to the hexane as an internal standard and the analysis conducted as before.
In these tests, the benzpyrene was recovered quantitatively. 相似文献
10.
Despite the popularity of JavaScript for client‐side web applications, there is a lack of effective software tools supporting JavaScript development and testing. The dynamic characteristics of JavaScript pose software engineering challenges such as program understanding and security. One important feature of JavaScript is that its objects support flexible mechanisms such as property changes at runtime and prototype‐based inheritance, making it difficult to reason about object behavior. We have performed an empirical study on real JavaScript applications to understand the dynamic behavior of JavaScript objects. We present metrics to measure behavior of JavaScript objects during execution (e.g., operations associated with an object, object size, and property type changes). We also investigated the behavioral patterns of observed objects to understand the coding or user interaction practices in JavaScript software. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献