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71.
Walker-256 tumor tissue was removed from rats on day 8 of tumor growth. An acidified methanol extract of the tumor tissue was assayed for immunoreactive (ir) dynorphin-A 1-17 (DYN-17) and ir-dynorphin-A (DYN-8). Levels of ir-DYN-17 and ir-DYN-8 were nearly 4-and 8-fold higher, respectively, in tumors versus normal muscle. However, tumor homogenates did not exhibit specific 3H-naloxone binding. These results indicate that although the Walker-256 carcinosarcoma may produce opioids, it is unlikely that these ectopic substances have direct opioid actions on the tumor itself. 相似文献
72.
Selective in vitro inhibition of human MOLT-4 T lymphoblasts by the novel purine nucleoside phosphorylase inhibitor, CI-972 总被引:1,自引:0,他引:1
R B Gilbertsen M K Dong L M Kossarek J C Sircar C R Kostlan M C Conroy 《Biochemical and biophysical research communications》1991,178(3):1351-1358
CI-972 (2,6-diamino-3,5-dihydro-7-(3-thienylmethyl)-4H-pyrrolo[3,2- d]pyrimidin-4-one monohydrochloride, monohydrate) is a competitive inhibitor of PNPase (E.C. 2.4.2.1., Ki = 0.83 microM) entering clinical trials as a T cell-selective immunosuppressive agent. Neither CI-972 (less than or equal to 50 microM) nor dGuo (less than or equal to 10 microM) inhibited [3H]Thd uptake by human MOLT-4 (T cell) or MGL-8 (B cell) lymphoblasts, but in the presence of 10 microM dGuo, the IC50 for CI-972 decreased to 3.0 microM for MOLT-4 but remained at greater than 50 microM for MGL-8. Inhibition of MOLT-4 growth was associated with an increase in dGTP that was dependent on CI-972 concentration and inhibited by 2'-deoxycytidine. Growth could not be restored by hypoxanthine or adenine. No alterations in GTP pools were noted in MOLT-4, and neither GTP nor dGTP were altered in MGL-8. 相似文献
73.
Richard Holmquist Morris Goodman Thomas Conroy John Czelusniak 《Journal of molecular evolution》1983,19(6):437-448
We have examined the extensive amino acid sequence data now available for five protein families - the alpha crystallin A chain, myoglobin, alpha and beta hemoglobin, and the cytochromes c - with the goal of estimating the true spatial distribution of base substitutions within genes that code for proteins. In every case the commonly used Poisson density failed to even approximate the experimental pattern of base substitution. For the 87 species of beta hemoglobin examined, for example, the probability that the observed results were from a Poisson process was the minuscule 10(-44). Analogous results were obtained for the other functional families. All the data were reasonably, but not perfectly, described by the negative binomial density. In particular, most of the data were described by one of the very simple limiting forms of this density, the geometric density. The implications of this for evolutionary inference are discussed. It is evident that most estimates of total base substitutions between genes are badly in need of revision. 相似文献
74.
An enzyme-linked immunosorbent assay for zein and other proteins using unconventional solvents for antigen adsorption 总被引:2,自引:0,他引:2
An enzyme-linked immunosorbent assay (ELISA) performed in polystyrene microtiter plates that can detect and quantitate the maize prolamin zein is described. The assay yields positive reactions with as little as 1 ng of antigen and uses solvents not ordinarily employed in ELISA methods. A systematic investigation of zein adsorption to polystyrene in various solvents supports the hypothesis that antigen binding occurs through nonpolar interactions. The method was also used to determine structural relationships among three zein polypeptides differing in size and charge. Additional experiments indicate that a number of soluble proteins are absorbed to polystyrene in the denaturing agent urea and retain immunological reactivity. The retention of antigen reactivity after solubilization in 6-8 M urea suggests that ELISA methods may be applicable to other proteins which are insoluble, or rendered insoluble, in aqueous buffers. 相似文献
75.
Inositol lipids and phosphates in the regulation of the growth and differentiation of haemopoietic and other cells 总被引:1,自引:0,他引:1
R H Michell L A Conroy M Finney P J French G Brown J A Creba C M Bunce J M Lord 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1990,327(1239):193-207
Stimulation of phosphatidylinositol 4,5-bisphosphate hydrolysis is an important signalling reaction involved in the responses of cells to some, but not all, stimuli that promote cell proliferation. Active agents in this regard include antigens activating T and B lymphocytes, angiotensin (employing a receptor encoded by the mas oncogene), bombesin and platelet-derived growth factor PDGF). However, accumulating evidence suggests that inositol lipids and phosphates also have other roles in the regulation of cell growth and differentiation. Growth factor receptors that encode tyrosine kinases (such as that for PDGF) activate a kinase that synthesises phosphatidylinositol 3-phosphate, a novel lipid, and loss of this kinase-activating function abolishes growth-promoting activity. Human interleukin-4, a lymphokine that activates B lymphocytes, appears to employ phosphatidylinositol 4,5-bisphosphate hydrolysis as a brief initial signal that is followed by a sustained rise in cyclic adenosine monophosphate (cAMP): both signals are needed for the successful induction of the surface antigen CD23. Moreover, the same inositol lipid signalling pathway as is employed by antigen-stimulated mature T lymphocytes to provoke proliferation may be redeployed in immature T cells to trigger their elimination when they encounter self-antigens. Finally, studies of HL60 promyelocytic cells have shown that these cells contain high concentrations of inositol 3,4,5,6-tetrakisphosphate, 1,3,4,5,6-pentakisphosphate and hexakisphosphate, three inositol polyphosphates that are probably formed independently of inositol lipid metabolism. When these cells are induced to differentiate either towards neutrophils (in the presence of dimethylsulphoxide) or macrophages (in phorbol myristate acetate), cessation of growth and acquisition of differentiated characteristics are accompanied by large and different changes in the concentrations of these inositol phosphates that may be characteristic of these two pathways of differentiation. 相似文献
76.
M W Vannier G C Conroy 《Folia primatologica; international journal of primatology》1989,53(1-4):22-32
Surface and volumetric three-dimensional imaging methods have found application in fields as diverse as diagnostic medical imaging and paleontological research. The acquisition, modeling, classification, and computer graphics rendering of discrete image volumes will be introduced. Applications in diagnosis (craniofacial, orthopedic, cardiovascular, and others) as well as reconstruction methods for generic serial sections will be described. C language software for three-dimensional reconstruction which operates on an IBM PC/AT clone is described. 相似文献
77.
MtDNA Evidence for Repeated Pulses of Speciation Within Arvicoline and Murid Rodents 总被引:8,自引:0,他引:8
We examined temporal aspects of phylogenetic relationships among 5 murid rodent subfamilies and 11 arvicoline genera based on DNA sequences of the cytochrome b gene (n = 92) and ND4 gene (n = 17). We found monophyly for Muridae but a polytomy among murid subfamilies. Arvicolinae was monophyletic, but most genera within this subfamily arose from a polytomy. Microtus was monophyletic, but within the genus, species arose rapidly. This pattern of nested pulses (polytomies) was recovered across parsimony, distance, and likelihood methods and indicates that accumulation of taxonomic diversity in murids was sporadic, rather than gradual. Arvicolines appeared in the Late Miocene and diversified later, between 3 and 5 million years ago. A relatively high rate of sequence evolution (i.e., 2.3% in third-position transversions per million years) helps reconcile the diversification of fossils and mtDNA lineages. 相似文献
78.
H C Watson N P Walker P J Shaw T N Bryant P L Wendell L A Fothergill R E Perkins S C Conroy M J Dobson M F Tuite et al. 《The EMBO journal》1982,1(12):1635-1640
The structure of yeast phosphoglycerate kinase has been determined with data obtained from amino acid sequence, nucleotide sequence, and X-ray crystallographic studies. The substrate binding sites, as deduced from electron density maps, are compatible with known substrate specificity and the stereochemical requirements for the enzymic reaction. A carboxyl-imidazole interaction appears to be involved in controlling the transition between the open and closed forms of the enzyme. 相似文献
79.
Shvedova AA Kapralov AA Feng WH Kisin ER Murray AR Mercer RR St Croix CM Lang MA Watkins SC Konduru NV Allen BL Conroy J Kotchey GP Mohamed BM Meade AD Volkov Y Star A Fadeel B Kagan VE 《PloS one》2012,7(3):e30923
Advancement of biomedical applications of carbonaceous nanomaterials is hampered by their biopersistence and pro-inflammatory action in vivo. Here, we used myeloperoxidase knockout B6.129X1-MPO (MPO k/o) mice and showed that oxidation and clearance of single walled carbon nanotubes (SWCNT) from the lungs of these animals after pharyngeal aspiration was markedly less effective whereas the inflammatory response was more robust than in wild-type C57Bl/6 mice. Our results provide direct evidence for the participation of MPO - one of the key-orchestrators of inflammatory response - in the in vivo pulmonary oxidative biodegradation of SWCNT and suggest new ways to control the biopersistence of nanomaterials through genetic or pharmacological manipulations. 相似文献
80.