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1.
2.
Summary The tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA) was examined for its ability to induce endogenous retrovirus from a high-passage clone
of Kirsten sarcoma virus-transformed Balb/c (K-Balb) mouse cells. TPA activated virus in a concentration-dependent manner
(0.0016 to 4.0 μM). Exposure to 1mM actinomycin D inhibited virus induction, suggesting that cellular RNA synthesis is required de novo by this inducer. A broad-spectrum
neutralizing antibody to murine type C virus, gp70, was shown to neutralize the infectivity of the induced virus. The activated
virus had the host range of the xenotropic Balb virus:2, and after removal of the inducer, the activated state decayed rapidly.
TPA stimulated DNA, RNA, and protein synthesis in K-Balb cells, indicating that the mechanism of inducation may be different
from that of previously identified virus inducers. The effects observed using the well-defined K-Balb system offer an opportunity
to study the modulation of retrovirus gene expression by TPA.
This work was conducted while the authors were with the Biological Carcinogenesis Program, Frederick Cancer Research Facility,
Frederick, MD 21701, and was supported under Contract NO1-CO-75380 with the National Cancer Institute, National Institutes
of Health, Bethesda, MD 20205. 相似文献
3.
Kin Sing Lam Salvatore Forenza Terrence W. Doyle Cedric J. Pearce 《Journal of industrial microbiology & biotechnology》1990,6(4):291-294
Summary Experimental evidence is presented to demonstrate that indolepyruvic acid is an intermediate in the rebeccamycin biosynthetic pathway. [3-14C]Indolepyruvic acid was prepared and efficiently incorporated (8%) into rebeccamycin bySaccharothrix aerocolonigenes. 相似文献
4.
In the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a Mr of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a Mr 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS-treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley-Liss, Inc. 相似文献
5.
Cedric Minkin Lenny Blackman Jarrett Newbrey Selma Pokress Robert Posek Marlin Walling 《Biochemical and biophysical research communications》1977,76(3):875-881
Peritoneal mononuclear phagocytes elicited by thioglycollate demonstrate responsiveness to parathyroid hormone (PTH) and calcitonin (CT) which differs from that seen in the normal resident population. PTH causes a twofold stimulation of adenylate cyclase activity in elicited cells but inhibits this activity in resident cells. CT causes a greater stimulation of adenylate cyclase in elicited than in resident cells. Both CT and PTH cause an increase in cyclic AMP accumulation in cultures of elicited mononuclear phagocytes. These results indicate that cells of the mononuclear phagocyte lineage have functional receptors for both PTH and CT. This is the first biochemical evidence to support the hypothesis that mononuclear phagocytes are precursors of the bone resorbing osteoclast. 相似文献
6.
Mice with Spontaneous Mammary Tumors Develop Type-Specific Neutralizing and Cytotoxic Antibodies Against the Mouse Mammary Tumor Virus Envelope Protein gp52
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Gerald Schochetman Larry O. Arthur Cedric W. Long Richard J. Massey 《Journal of virology》1979,32(1):131-139
Sera from C3H mammary tumor-bearing mice contain cytotoxic antibodies for mouse mammary tumor virus (MMTV)-producing cells, based on (51)Cr release in a complement-dependent serum cytotoxicity assay. The cytotoxic antibodies could be absorbed by purified C3H MMTV gp52 and C3H MMTV-infected cat cells (C3H [MMTV] CrFK) containing cell surface MMTV gp52. However, purified MMTV p27 and uninfected CrFK cat cells were negative. Absorption of the sera with GR (MMTV) CrFK cells also removed all of the cytotoxicity, whereas absorption with RIII (MMTV) CrFK cells was negative, even though all three infected cat cells contained equivalent amounts of gp52. The same C3H cytotoxic sera also neutralized the focus-forming capacity of a C3H MMTV pseudotype of Kirsten sarcoma virus containing MMTV gp52. In contrast, sera from mammary tumor-bearing GR and RIII mice did not neutralize the pseudotype. Furthermore, neutralization could be achieved only by anti-gp52 but not by anti-gp36, -p27, -p14, or -p10 C3H MMTV sera. The gp52's of C3H, GR, and RIII MMTV could also be distinguished by using a type-specific competition radioimmunoassay employing (125)I-gp52 of C3H MMTV and a hyperimmune rabbit anti-C3H MMTV serum. To demonstrate these differences directly, we studied the primary structure of gp52 on the surface of the C3H, GR, and RIII (MMTV) CrFK cells. Two-dimensional tryptic peptide maps of the cell surface lactoper-oxidase-catalyzed iodinated gp52's revealed a greater number of peptides common to the gp52's of C3H and GR MMTVs than to RIII MMTV gp52. These results demonstrate that gp52 is a major target antigen for both cytotoxic and neutralizing antibodies, that the cell surface and virion-associated gp52's of C3H, GR, and RIII MMTV contain both group- and type-specific determinants, and that C3H and GR MMTV gp52's are antigenically more related to each other than to RIII MMTV gp52. Furthermore, C3H mammary tumor-bearing mice develop type-specific antibodies capable of recognizing unique gp52 determinants and, therefore, are able to distinguish the gp52 of C3H MMTV from the gp52's of GR and RIII MMTV. 相似文献
7.
Frans A. Kuypers Peter Bütikofer Cedric H.L. Shackleton 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,562(1-2)
We report the application of high-performance liquid chromatographic (HPLC) separation with ultraviolet detection and direct, on-line, structural analyses by mass spectrometry of glycerobenzoate derivatives from complex mixtures of phospholipid molecular species. Individual phospholipids were resolved from total lipid extracts by thin-layer chromatography (TLC). Diradylglycerols were released from phospholipids by phospholipase-C treatment, converted to diradyl glycerobenzoates and subsequently separated by TLC into subclasses (alk-1-enylacyl, alkylacyl and diacyl types). The molecular species within each subclass were resolved by HPLC with an octadecyl reversed-phase column in acetonitrile—isopropanol (80:20, v/v). Individual peaks were quantitated at the picomole level by measuring absorbance at 230 nm. After post-column addition of methanol—0.2 M ammonium acetate (50:50, v/v), peaks were introduced through the thermospray interface into a VG Masslab 30–250 quadrupole mass spectrometer. Molecular species showed as base peaks the salt adducts of the molecular ion which permitted easy deduction of the overall fatty acyl composition. In addition, the diglyceride fragment of each species was found at [MH — 122]+ and two fragments formed by the loss of the fatty acyl groups (R) in the sn-1 or sn-2 position were found at [M — R1]+ and [M — R2]+, respectively. Since preferential release of either fatty acyl group was observed in positional isomers, the ratio of the intensity of these fragments gave information on the position of the fatty acyl groups in the individual HPLC peaks. We show that the use of on-line mass spectrometry, however, provides easy identification of all molecular species present in a complex phospholipid mixture, even when more than one molecular species is contained in an HPLC peak. 相似文献
8.
Properties of Bovine Oligodendroglia Isolated by a New Procedure Using Physiologic Conditions 总被引:6,自引:5,他引:1
Muhammad Farooq Wendy Cammer D. Stephen Snyder Cedric S. Raine William T. Norton 《Journal of neurochemistry》1981,36(2):431-440
A new class of procedures, previously shown to permit the isolation of pure oligodendroglia from whole rat cerebrum, has been applied with equal or greater success for the bulk isolation of this cell type from bovine white matter. Thus, the generality of this approach has been demonstrated. The bovine preparations have a purity of greater than 90% intact, phase-bright oligodendroglia and are obtained in a yield of 8 x 10(6) cells per gram of white matter. Within 1 day it is possible to obtain a preparation containing 60 mg of protein from a single cell type. These cells show a higher degree of ultrastructural preservation of all cytoplasmic constituents than previously obtained. The values for protein (33 pg/cell), DNA (5.4 pg/cell), and lipid (5-6 pg/cell) are very similar to those obtained with an earlier procedure. The cell lipids are rich in galactolipid, which comprises 20% of the total. The activity of the "myelin-specific" enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (EC 3.1.4.37), is 4.7 mumol/min/mg protein, similar to that obtained previously for isolated oligodendroglia and about 25-40% of that found in myelin. The activity of 5'-nucleotidase (EC 3.1.3.5) in the cells is about 10% of that in myelin or white matter. 相似文献
9.
Beno?te Méry Jean-Baptiste Guy Sophie Espenel Anne-Sophie Wozny Stéphanie Simonet Alexis Vallard Gersende Alphonse Dominique Ardail Claire Rodriguez-Lafrasse Nicolas Magné 《World journal of stem cells》2016,8(1):13-21
Head and neck squamous cell cancer(HNSCC) is the sixth most common cancer in the world. Effective therapeutic modalities such as surgery, radiation, chemotherapy and combinations of each are used in the management of the disease. In most cases, treatment fails to obtain total cancer cure. In recent years, it appears that one of the key determinants of treatment failure may be the presence of cancer stem cells(CSCs) that escape currently available therapies. CSCs form a small portion of the total tumor burden but may play a disproportionately important role in determining outcomes. CSCs have stem features such as self-renewal, high migration capacity, drug resistance, high proliferation abilities. A large body of evidence points to the fact that CSCs are particularly resistant to radiotherapy and chemotherapy. In HNSCC, CSCs have been increasingly shown to have an integral role in tumor initiation, disease progression, metastasis and treatment resistance. In the light of such observations, the present review summarizes biological characteristics of CSCs in HNSCC, outlines targeted strategies for the successful eradication of CSCs in HNSCC including targeting the self-renewal controlling pathways, blocking epithelial mesenchymal transition, niche targeting, immunotherapy approaches and highlights the need to better understand CSCs biology for new treatments modalities. 相似文献
10.
G protein-dependent CCR5 signaling is not required for efficient infection of primary T lymphocytes and macrophages by R5 human immunodeficiency virus type 1 isolates
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Amara A Vidy A Boulla G Mollier K Garcia-Perez J Alcamí J Blanpain C Parmentier M Virelizier JL Charneau P Arenzana-Seisdedos F 《Journal of virology》2003,77(4):2550-2558
The requirement of human immunodeficiency virus (HIV)-induced CCR5 activation for infection by R5 HIV type 1 (HIV-1) strains remains controversial. Ectopic CCR5 expression in CD4(+)-transformed cells or pharmacological inhibition of G(alpha)i proteins coupled to CCR5 left unsolved whether CCR5-dependent cell activation is necessary for the HIV life cycle. In this study, we investigated the role played by HIV-induced CCR5-dependent cell signaling during infection of primary CD4-expressing leukocytes. Using lentiviral vectors, we restored CCR5 expression in T lymphocytes and macrophages from individuals carrying the homozygous 32-bp deletion of the CCR5 gene (ccr5 Delta32/Delta32). Expression of wild-type (wt) CCR5 in ccr5 Delta32/Delta32 cells permitted infection by R5 HIV isolates. We assessed the capacity of a CCR5 derivative carrying a mutated DRY motif (CCR5-R126N) in the second intracellular loop to work as an HIV-1 coreceptor. The R126N mutation is known to disable G protein coupling and agonist-induced signal transduction through CCR5 and other G protein-coupled receptors. Despite its inability to promote either intracellular calcium mobilization or cell chemotaxis, the inactive CCR5-R126N mutant provided full coreceptor function to several R5 HIV-1 isolates in primary cells as efficiently as wt CCR5. We conclude that in a primary, CCR5-reconstituted CD4(+) cell environment, G protein signaling is dispensable for R5 HIV-1 isolates to actively infect primary CD4(+) T lymphocytes or macrophages. 相似文献