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1.
In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera9. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo10,11, which has been tentatively attributed to its unblocking activity8,9 or, possibly, to a complement-dependent cytotoxicity10. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity9,10. 相似文献
2.
On the mechanism of ATP-induced shape changes in the human erythrocyte membranes: the role of ATP
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In the preceding paper (Sheetz, M. and S.J. Singer. 1977. J Cell Biol. 73:638-646) it was shown that erythrocyte ghosts undergo pronounced shape changes in the presence of mg-ATP. The biochemical effects of the action of ATP are herein examined. The biochemical effects of the action of ATP are herein examined. Phosphorylation by ATP of spectrin component 2 of the erythrocyte membrane is known to occur. We have shown that it is only membrane protein that is significantly phosphorylated under the conditions where the shape changes are produced. The extent of this phosphorylation rises with increasing ATP concentration, reaching nearly 1 mol phosphoryle group per mole of component 2 at 8mM ATP. Most of this phosphorylation appears to occur at a single site on the protein molecule, according to cyanogen bromide peptide cleavage experiments. The degree of phosphorylation of component 2 is apparently also regulated by a membrane-bound protein phosphatase. This activity can be demonstrated in erythrocyte ghosts prepared from intact cells prelabeled with [(32)P]phosphate. In addition to the phosphorylation of component 2, some phosphorylation of lipids, mainly of phosphatidylinositol, is also known to occur. The ghost shape changes are, however, shown to be correlated with the degree of phosphorylation of component 2. In such experiment, the incorporation of exogenous phosphatases into ghosts reversed the shape changes produced by ATP, or by the membrane-intercalating drug chlorpromazine. The results obtained in this and the preceding paper are consistent with the proposal that the erythrocyte membrane possesses kinase and phosphates activities which produce phosphorylation and dephosphorylation of a specific site on spectrin component 2 molecules; the steady-state level of this phosphorylation regulates the structural state of the spectrin complex on the cytoplasmic surface of the membrane, which in turn exerts an important control on the shape of the cell. 相似文献
3.
Gold salts and phenylbutazone selectively inhibit the synthesis of PGF2α and PGE2 respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE2 and PGF2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action
and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function. 相似文献
4.
David M. Wilson James Apps Nicholas Bailey Mark J. Bamford Isabel J. Beresford Michael A. Briggs Andrew R. Calver Barry Crook Robert P. Davis Susannah Davis David K. Dean Leanne Harris Tom D. Heightman Terry Panchal Christopher A. Parr Nigel Quashie Jon G.A. Steadman Joanne Schogger Andrew D. Medhurst 《Bioorganic & medicinal chemistry letters》2013,23(24):6897-6901
This Letter describes the discovery of a novel series of H3 receptor antagonists. The initial medicinal chemistry strategy focused on deconstructing and simplifying an early screening hit which rapidly led to the discovery of a novel series of H3 receptor antagonists based on the benzazepine core. Employing an H3 driven pharmacodynamic model, the series was then further optimised through to a lead compound that showed robust in vivo functional activity and possessed overall excellent developability properties. 相似文献
5.
6.
Pasquier CM; Promponas VI; Varvayannis NJ; Hamodrakas SJ 《Bioinformatics (Oxford, England)》1998,14(8):749-750
Summary : FT is a tool written in C++, which implements the Fourier
analysis method to locate periodicities in aminoacid or DNA sequences. It
is provided for free public use on a WWW server with a Java interface.
Availability : The server address is http://o2.db. uoa.gr/FT Contact :
shamodr@atlas.uoa.gr
相似文献
7.
R. Bruce Medhurst Mark S. Wipfli Chris Binckley Karl Polivka Paul F. Hessburg R. Brion Salter 《Hydrobiologia》2010,641(1):71-83
Effects of forest management on stream communities have been widely documented, but the role that climate plays in the disturbance
outcomes is not understood. In order to determine whether the effect of disturbance from forest management on headwater stream
communities varies by climate, we evaluated benthic macroinvertebrate communities in 24 headwater streams that differed in
forest management (logged-roaded vs. unlogged-unroaded, hereafter logged and unlogged) within two ecological sub-regions (wet
versus dry) within the eastern Cascade Range, Washington, USA. In both ecoregions, total macroinvertebrate density was highest
at logged sites (P = 0.001) with gathering-collectors and shredders dominating. Total taxonomic richness and diversity did not differ between
ecoregions or forest management types. Shredder densities were positively correlated with total deciduous and Sitka alder
(Alnus sinuata) riparian cover. Further, differences in shredder density between logged and unlogged sites were greater in the wet ecoregion
(logging × ecoregion interaction; P = 0.006) suggesting that differences in post-logging forest succession between ecoregions were responsible for differences
in shredder abundance. Headwater stream benthic community structure was influenced by logging and regional differences in
climate. Future development of ecoregional classification models at the subbasin scale, and use of functional metrics in addition
to structural metrics, may allow for more accurate assessments of anthropogenic disturbances in mountainous regions where
mosaics of localized differences in climate are common. 相似文献
8.
Jane Medhurst Geoff Downes Maria Ottenschlaeger Chris Harwood Rob Evans Chris Beadle 《Trees - Structure and Function》2012,26(6):1771-1780
In eucalypt plantations managed for solid-wood products, radial trends in wood density, microfibril angle (MFA) and stiffness (modulus of elasticity, MoE) are properties of potential commercial importance that can be affected by competition from neighbouring trees. In this study, wood properties at breast height (1.3?m) were studied on radial strips prepared from 12-mm pith-to-bark wood cores taken from 20 trees in a 22-year-old Eucalyptus nitens (Deane and Maiden) Maiden thinning trial in north-eastern Tasmania, Australia. Thinning treatments were applied at age 6?years. Trees were sampled from each of the 200, 400?stems ha?1 and unthinned control treatments. Intra-specific competition for each sampled tree was estimated using the basal area growth of surrounding trees. SilviScan? technology was used to produce radial profiles of wood density, MFA and MoE. Results indicate a reduction in intra-specific competition through thinning of E. nitens plantations at an early age leads to a transient increase in MFA but has no significant effect on wood density or the intra-annual cycle of wood density. The correlation between the level of intra-specific competition and initial change in MFA following thinning, and a significant relationship between tree shape and mean MFA at breast height suggests the change in MFA is a post-thinning response to increased exposure and wind sway. 相似文献
9.
This study tested the hypothesis that the relationship between leaf area (projected, or one‐sided) and sapwood area in Eucalyptus nitens (Deane and Maiden) Maiden is affected by thinning treatment. However, no difference in the relationship between leaf area and sapwood area was found 8 years after thinning. This result suggests that a single regression equation can be used to predict the leaf area of trees in thinned and unthinned stands. The relationship was non‐linear, implying a causal relationship between growth rate and the ratio of leaf area to sapwood area (Al : As). Sapwood hydraulic conductivity increased by approximately 100% from breast height to crown base, whereas sapwood area decreased by 19%. This implies that the efficiency of water transport through the sapwood increased by 60% along this length. This conclusion is supported by the Al : As relationships which showed that the sapwood area at crown base supported, on average, close to 60% more leaf area than a similar amount of sapwood area at breast height. That large trees in this study had greater hydraulic conductivity and higher Al : As lends support to the argument that resource capture, and hence growth rate, influence sapwood hydraulic conductivity. 相似文献
10.
Amiloride does not alter NaCl avoidance in Fischer-344 rats 总被引:2,自引:2,他引:0
Fischer-344 (F-344) rats differ from other common rat strains in that they
fail to show any preference for NaCl at any concentration in two- bottle
preference tests. Because 100 microM amiloride partially blocks the
NaCl-evoked chorda tympani (CT) response in electrophysiological studies,
we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without
100 microM amiloride solution as the solvent. A third group was tested with
unadulterated NaCl solutions following CT transection. Amiloride had no
significant effect on the NaCl preference-aversion function, whereas CT
transection significantly reduced NaCl avoidance. These results suggest
that the amiloride-sensitive component of the NaCl response is not
necessary for F-344 rats to display avoidance of NaCl, but the entire CT
input is.
相似文献