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311.
John de Majnik R. G. Joseph G. J. Tanner P. J. Larkin M. A. Djordjevic B. G. Rolfe J. J. Weinman 《Plant Molecular Biology Reporter》1997,15(2):134-140
A set of vectors has been developed that simplify shuttling expression cassettes between small plasmids of high copy number
ideal for experiments involving biolistic transient expression and a binary transformation plasmid. Three cassettes for the
expression of a cloned coding sequence behind different promoters have been modified; combinations of these cassettes can
be excised withNot I, and sequentially cloned into the transformation vector in a procedure that removes the first cloning site. The system
is demonstrated by inducing anthocyanin synthesis with paired regulatory genes of maize biolistically delivered to a maize
cell suspension, and then expressed in transformed tobacco. 相似文献
312.
Stimulation of immune suppressive CD34+ cells from normal bone marrow by Lewis lung carcinoma tumors
Mark A. Wright Kristina Wiers Kishore Vellody Dragana Djordjevic M. Rita I. Young 《Cancer immunology, immunotherapy : CII》1998,46(5):253-260
Progressive growth of metastatic Lewis lung carcinoma (LLC-LN7) tumors is associated with increased levels of bone-marrow-derived
CD34+ cells having natural suppressor (NS) activity toward T cells. The present studies determined whether tumor-derived products
are responsible for this induction of NS activity. Culturing normal bone marrow cells with LLC-LN7-conditioned medium (LLC-CM)
or with recombinant granulocyte/macrophage-colony-stimulating factor (GM-CSF) resulted in the appearance of NS activity. The
development of NS activity coincided with a prominent increase in the levels of CD34+ cells. That the CD34+ cells were responsible for the NS activity of the bone marrow cultures containing LLC-CM was shown by the loss of NS activity
when CD34+ cells were depleted. The stimulation of CD34+ NS cells by LLC-CM was attributed to tumor production of GM-CSF, since neutralization of GM-CSF within the LLC-CM reduced
its capacity to increase CD34+ cell levels. Studies also showed that the induction of CD34+ NS cells by LLC-CM and GM-CSF could be overcome by including in the cultures an inducer of myeloid differentiation, 1α,25-dihydroxyvitamin
D3 [1,25(OH)2D3]. These results demonstrate that the mechanism by which the LLC-LN7 tumors stimulate increased levels of CD34+ NS cells from normal bone marrow is by their production of GM-CSF and that this can be blocked with the myeloid differentiation
inducer 1,25(OH)2D3.
Received: 8 December 1997 / Accepted: 27 February 1998 相似文献
313.
Human clinical and psychophysical observations suggest that the taste
system is able to compensate for losses in peripheral nerve input, since
patients do not commonly report decrements in whole mouth taste following
chorda tympani nerve damage or anesthesia. Indeed, neurophysiological data
from the rat nucleus of the solitary tract (NST) suggests that a release of
inhibition (disinhibition) may occur centrally following chorda tympani
nerve anesthesia. Our purpose was to study this possibility further. We
recorded from 59 multi- and single- unit taste-responsive sites in the rat
NST before, during and after recovery from chorda tympani nerve anesthesia.
During anesthesia, average anterior tongue responses were eliminated but no
compensatory increases in palatal or posterior tongue responses were
observed. However, six individual sites displayed increased taste
responsiveness during anesthesia. The average increase was 32.9%.
Therefore, disinhibition of taste responses was observed, but infrequently
and to a small degree in the NST At a subset of sites, chorda
tympani-mediated responses decreased while greater superficial
petrosal-mediated responses remained the same during anesthesia. Since this
effect was accompanied by a decrease in spontaneous activity, we propose
that taste compensation may result in part by a change in signal-to-noise
ratio at a subset of sites.
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