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81.
Poly(arylene-1,2,4-oxadiazole)s (PAOs) bearing flexible, linear side chains, 3a - c , were prepared by solution cyclodehydration of their precursors, poly(arylene acyloylamide oxime)s (PAAs), 2a - c , which were synthesized by solution polycondensation of 2,5-bis(n-alkoxymethyl)-terephthaldiamide oximes (DIS-TADO), 1a - c , with terephthaloyl dichloride (TPC). The length of the n-alkoxy group was varied from methoxy via butoxy to octyloxy. The reduction of the phase transition temperatures and the enhancement of the solubilities of 3a - c were greatly affected by the length of the side chains. PAOs with longer side chains, 3b and 3c , are nematic type liquid-crystalline polymers. 相似文献
82.
83.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
84.
85.
Involvement of pp60c-src with two major signaling pathways in human breast cancer. 总被引:14,自引:3,他引:11
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D K Luttrell A Lee T J Lansing R M Crosby K D Jung D Willard M Luther M Rodriguez J Berman T M Gilmer 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(1):83-87
The phosphotyrosine residues of receptor tyrosine kinases serve as unique binding sites for proteins involved in intracellular signaling, which contain SRC homology 2 (SH2) domains. Since overexpression or activation of the pp60c-src kinase has been reported in a number of human tumors, including primary human breast carcinomas, we examined the interactions of the SH2 and SH3 domains of human SRC with target proteins in human carcinoma cell lines. Glutathione S-transferase fusion proteins containing either the SH2, SH3, or the entire SH3/SH2 region of human SRC were used to affinity purify tyrosine-phosphorylated proteins from human breast carcinoma cell lines. We show here that in human breast carcinoma cell lines, the SRC SH2 domain binds to activated epidermal growth factor receptor (EGFR) and p185HER2/neu. SRC SH2 binding to EGFR was also observed in a nontumorigenic cell line after hormone stimulation. Endogenous pp60c-src was found to tightly associate with tyrosine-phosphorylated EGFR. Association of the SRC SH2 with the EGFR was blocked by tyrosyl phosphopeptides containing the sequences surrounding tyrosine-530, the regulatory site in the SRC C terminus, or sequences surrounding the major sites of autophosphorylation in the EGFR. These results raise the possibility that association of pp60c-src with these receptor tyrosine kinases is an integral part of the signaling events mediated by these receptors and may contribute to malignant transformation. 相似文献
86.
Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
87.
Cytogenetic analysis, confirmed by in situ hybridisation studies, showed a mosaic 45,X/46,X dic (Y) (q12) karyotype in a 14 year old boy who was initially diagnosed as having Noonan''s syndrome. He made an early response to recombinant growth hormone; this suggests that this treatment may improve final height. 相似文献
88.
Dong-Hyun Kim Eun-Ah Jung In-Suk Sohng Jung-Ah Han Tae-Hyung Kim Myung Joo Han 《Archives of pharmacal research》1998,21(1):17-23
Flavonoid glycosides were metabolized to phenolic acids via aglycones by human intestinal microflora producing α-rhamnosidase, exo-β-glucosidase, endo-β-glucosidase and/or β-glucuronidase. Rutin, hesperidin, naringin and poncirin were transformed to their aglycones by the bacteria producing α-rhamnosidase and β-glucosidase or endo-β-glucosidase, and baicalin, puerarin and daidzin were transformed to their aglycones by the bacteria producing β-glucuronidase, C-glycosidase and β-glycosidase, respectively. Anti-platelet activity and cytotoxicity of the metabolites of flavonoid glycosides by human intestinal bacteria were more effective than those of the parental compounds. 3,4-Dihydroxyphenylacetic acid and 4-hydroxyl-phenylacetic acid were more effective than rutin and quercetin on anti-platelet aggregation activity. 2,4,6-Trihydroxybenzaldehyde, quercetin and ponciretin were more effective than rutin and ponciretin on the cytotoxicity for tumor cell lines. We insist that these flavonoid glycosides should be natural prodrugs. 相似文献
89.
90.