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81.
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Antibody-selected variation and reversion in Sindbis virus neutralization epitopes. 总被引:12,自引:9,他引:3 下载免费PDF全文
Sindbis virus variants evidencing a complex and bidirectional tendency toward spontaneous antigenic change were isolated and characterized. Variants were selected on the basis of their escape from neutralization by individual monoclonal antibodies to either of the two envelope glycoproteins, E2 and E1. Multisite variants, including one altered in three neutralization sites, were obtained by selecting mutants consecutively in the presence of different neutralizing monoclonal antibodies. Two phenotypic revertants, each of which reacquired prototype antigenicity, were back-selected on the basis of their reactivity with a neutralizing monoclonal antibody. An incidental oligonucleotide marker distinguished these and the variant from which they arose from parental Sindbis virus and other mutants, thereby confirming that the revertants were true progeny of the antigenic variant. Prototype Sindbis virus and variants derived from it were compared on the basis of their reactivities with each of a panel of monoclonal antibodies; patterns revealed a minimum of five independently mutable Sindbis virus neutralization epitopes, segregating as three antigenic sites (two E2 and one E1). 相似文献
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Phanpimol Bunnag Karen S. Waddell M. Lee Varban Ing-Ming Chiu 《In vitro cellular & developmental biology. Animal》1991,27(1):89-96
Summary Heparin-binding growth factor 1 (HBGF-1), also known as acidic fibroblast growth factor, is a potent mitogen and angiogenic
factor found in tissues such as brain, kidney and heart. The genomic and cDNA sequences indicate that HBGF-1 does not have
a typical signal peptide sequence. HBGF-1 was shown to be localized to the extracellular matrix of cardiac myocytes, but the
mechanism of secretion is not presently known. We have cloned the HBGF-1 cDNA which allowed us to directly test the biological
activity, mechanism of secretion and transforming potential of the recombinant protein. A previous report showed that the
truncated HBGF-1 confers partial transformed phenotype to the recipient fibroblasts. However, expression of full-length HBGF-1
has not been reported. The HBGF-1 coding sequence was cloned into the retroviral expression vector, SVX, and transfected into
NIH/3T3 cells. Transfectants expressing full-length HBGF-1 protein at high levels form foci and grow to a higher cell density
than the parental NIH/3T3 cells. Western blotting analysis showed that the recombinant HBGF-1 is a unique band of approximately
20 kDa and can be detected in the cell homogenate but not in the conditioned medium. NIH/3T3 cells were conferred anchorage
independence when HBGF-1 was provided exogenously. We showed the transformed cells are capable of growing on soft agar even
in the absence of exogenously-provided HBGF-1. Transfected cells expressing HBGF-1 also induced tumor formation when injected
into nude mice. Thus, NIH/3T3 cells acquired a full spectrum of transformed phenotype when full length HBGF-1 was expressed
at high levels.
This work was supported by grants from the National Cancer Institute (RO1 CA45611), The March of Dimes Birth Defects Foundation
(No. 6-549) and The Ohio Cancer Research Associates, Inc. I.-M.C. is a recipient of The Research Career Development Award
(KO4 CA01369) from the National Institutes of Health. 相似文献
85.
A medium for the detection of Lancefield Group D cocci in skimmed milk powder by measurement of conductivity changes 总被引:1,自引:0,他引:1
A selective medium for the detection of Lancefield Group D cocci in skimmed milk powder by conductivity measurements was developed and evaluated using the Bactometer M123 and Malthus 128H systems. This medium promoted large changes in conductance and capacitance. The calibration curve of detection times vs concentration of Lancefield Group D cocci showed a linear correlation coefficient of 0.93 and the method gave comparable results in both conductivity instruments. Naturally contaminated samples containing c. 10(3) cfu/g of Lancefield Group D cocci gave detection times within 16-18 h which was sufficiently rapid for the medium to be used for the routine screening of skimmed milk powder. 相似文献
86.
The identification of T2; the phosphate/pyrophosphate transport protein of the hepatic microsomal glucose-6-phosphatase system 总被引:1,自引:0,他引:1
The phosphate/pyrophosphate translocase protein (T2) of the hepatic microsomal glucose-6-phosphatase system was identified and then purified using antibodies raised against the rat mitochondrial phosphate/hydroxyl ion antiport protein. The T2 protein was shown to be absent in the microsomes isolated from a patient previously diagnosed as having type lc glycogen storage disease. 相似文献
87.
Studies of pulse-type gymnotiform electric fishes have suggested that electric organ discharge waveforms (EODw) allow individuals to discriminate between conspecific and allospecific signals, but few have approached this experimentally. Here we implement a phase-locked playback technique for a syntopic species pair, Brachyhypopomus gauderio and Gymnotus omarorum. Both species respond to changes in stimulus waveform with a transitory reduction in the interpulse interval of their self-generated discharge, providing strong evidence of discrimination. We also document sustained rate changes in response to different EODws, which may suggest recognition of natural waveforms. 相似文献
88.
The amount of treatment received by 380 patients with backache was found to have been influenced more by their distress and illness behaviour than by the actual physical disease. Patients showing a large amount of inappropriate illness behaviour had received significantly more treatment (p less than 0.001). The symptoms and signs of illness behaviour need to be clearly distinguished from those of physical disease, and better assessment of illness behaviour is essential if everyday clinical practice is to fulfil the ideal of treating patients as well as diseases. 相似文献
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