Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied purified preparations of murine mammary tumor virus (MuMTV), Rous sarcoma virus (RSV; Prague strain), and feline leukemia virus (FeLV) by laser beat frequency light-scattering spectroscopy, ultra-centrifugation, and electron microscopy. The laser beat frequency light-scattering spectroscopy measurements yield the light-scattering intensity, weighted diffusion coefficients. The corresponding average hydrodynamic diameters, as calculated from the diffusion coefficients by the Stokes-Einstein equation for MuMTV, RSV, and FeLV, respectively, are: 144 +/- 6 nm, 147 +/- 7 nm, and 168 +/- 6 nm. Portions of the purified RSV and MuMTV preparations, from which light-scattering samples were obtained, and portions of the actual FeLV light-scattering samples were examined by negatively stained, catalase crystal-calibrated electron microscopy. The light-scattering intensity weighted averages of the electron micrograph size distributions were calculated by weighing each size by its theoretical relative scattering intensity, as obtained from published tables computed according to the Mie scattering theory. These averages and the experimentally observed hydrodynamic diameters agreed to within +/- 5%, which is the combined experimental error in the electron microscopic and light-scattering techniques. We conclude that the size distributions of singlet particles observed in the electron micrographs are statistically true representations of the sedimentation-purified solution size distributions. The sedimentation coefficients (S20, w) for MuMTV, RSV, and FeLV, respectively, are: 595 +/- 29S, 689 +/- 35S, and 880 +/- 44S. Virus partial specific volumes were taken as the reciprocals of the buoyant densities, determined in sucrose density gradients. The Svedberg equation was used to calculate particle weights from the measured diffusion and sedimentation coefficients. The particle weights for MuMTV, RSV, and FeLV, respectively, are: (3.17 +/- 0.32) x 10(8), (4.17 +/- 0.42) x 10(8), and (5.50 +/- 0.55) x 10(8) daltons.
 ...
PMID:Hydrodynamic diameters of murine mammary, Rous sarcoma, and feline leukemia RNA tumor viruses: studies by laser beat frequency light-scattering spectroscopy and electron microscopy. 17 31

Computerised axial tomography (CAT scan) was performed in 22 children with acute lymphoblastic leukaemia and in 13 the results were normal. In the other nine, various lesions were observed; namely intra-parenchymal lesions of density of (3 cases, one of which was calcified), intra-parenchymal lesions of decreased density (2 cases) and ventricular dilatation (7 cases). The role of the disease and of the treatment (intra-thecal methotrexate, cranial irradiation) in the development of these lesions is discussed. The CAT scan is an excellent method of monitoring the neurological problems in acute lymphoblastic leukaemia.
 ...
PMID:[Results of brain tomography in acute lymphoblastic leukemia in children]. 29 51

The catalase activities of HP50-2 and HP100-1 cells, which are H2O2-resistant cell lines derived from human leukemia HL-60 cells, were 3 and 18 times higher, respectively, than that of HL-60 cells. These catalase activities of the resistant cells were precipitated with anti-catalase serum. The glutathione peroxidase activity of HP50-2 cells was about twice that of HL-60 or HP100-1 cells. The superoxide dismutase activities of HP50-2 and HP100-1 cells were, respectively, about 4 and 2 times that of HL-60 cells. In addition, both the resistant cell lines were completely devoid of myeloperoxidase activity. Pulse-labeling experiments showed that the syntheses of catalase in HP50-2 and HP100-1 cells were, respectively, 2 and 4 times that in HL-60 cells, and that, unlike the parent cells, neither line synthesized myeloperoxidase. Thus the alteration of catalase, glutathione peroxidase, and superoxide dismutase activity could be linked to the resistance of H2O2 of human leukemia cells.
 ...
PMID:High production of catalase in hydrogen peroxide-resistant human leukemia HL-60 cell lines. 131 86

Human embryonal carcinoma is thought to be a counterpart of mouse embryonal carcinoma, which has provided useful information for studying early molecular events in murine embryogenesis. A major practical problem in the use of human embryonal carcinoma for molecular pathological studies is the lack of an efficient expression system for foreign genes. The SR alpha promoter is a fusion promoter containing the SV 40 early promoter and the R segment and part of the U5 sequence of the long terminal repeat derived from human T-cell leukemia virus type I. We analyzed the expression pattern of the SR alpha promoter in human and mouse embryonal carcinoma lines and transgenic mouse tissues. Efficient and stable expression was detected in all cell lines tested, and tissues from all mice of four independent transgenic lines carrying the SR alpha-CAT vector showed a detectable level of CAT expression. These data suggest that the SR alpha promoter is useful for studies of both human embryonal carcinoma and transgenic mouse tissue. Using this expression system, we are now able to label human embryonal carcinomas with various genes, for example beta galactosidase, and follow their fate at the single-cell level in nude mice, where xenotransplanted human embryonal carcinoma expresses differentiation capability.
 ...
PMID:Expression pattern of SR alpha promoter in human embryonal carcinoma and transgenic tissues in mice. 133 14

Merocyanine 540 (MC540) is a photosensitizing dye that has been used in several preclinical models and in a phase I clinical trial for the extracorporeal purging of tumor cells from autologous bone marrow grafts. The mechanism of the cytotoxic activity of MC540 is not yet fully understood, and the subcellular targets of MC540-mediated photodynamic damage remain to be identified. The human neutrophil provides an attractive model with which to study the effects of photoactivated MC540 on several well-defined cellular functions. As we report in this paper, simultaneous exposure of neutrophils to MC540 and light inhibited phagocytosis, random migration, chemotaxis, hydrogen peroxide production, and oxygen consumption. By contrast, the ability of neutrophils to kill engulfed bacteria and to produce superoxide radical was not compromised. Intracellular ATP levels and the activities of the cytosolic enzymes superoxide dismutase, catalase, and myeloperoxidase were only slightly reduced. Even in HL-60 leukemia cells, which bind more dye and are more readily killed by MC540-mediated photodynamic therapy than neutrophils, superoxide dismutase, catalase, and myeloperoxidase activities remained at normal or near-normal levels. These results are compatible with the view that plasma membrane components are primary targets of MC540-mediated photodynamic damage.
 ...
PMID:Photodamaging effects of merocyanine 540 on neutrophils and HL-60 cells. 133 24

NF-kappa B is a protein complex which functions in concert with the tat-I gene product to stimulate human immunodeficiency virus (HIV) transcription. To determine whether specific members of the NF-kappa B family contribute to this effect, we have examined the abilities of different NF-kappa B subunits to act with Tat-I to stimulate transcription of HIV in Jurkat T-leukemia cells. We have found that the p49(100) DNA binding subunit, together with p65, can act in concert with Tat-I to stimulate the expression of HIV-CAT plasmid. Little effect was observed with 50-kDa forms of p105 NF-kappa B or rel, in combination with p65 or full-length c-rel, which do not stimulate the HIV enhancer in these cells. These findings suggest that the combination of p49(100) and p65 NF-kappa B can act in concert with the tat-I gene product to stimulate the synthesis of HIV RNA.
 ...
PMID:Specific NF-kappa B subunits act in concert with Tat to stimulate human immunodeficiency virus type 1 transcription. 158 34

Previously we isolated revertants from a rat cell line transformed by recombinant murine retrovirus containing the v-src gene. These mutant cell lines, R78 and R107, showed low src-kinase activity, but retained wild-type transforming retrovirus, suggesting that a cellular gene involved in viral gene expression was mutated. Southern and Northern hybridization analyses showed that the expression of viral mRNAs from the integrated proviral DNA was reduced in these mutant cells. DNA transfection experiments with various transforming genes and promoters revealed that the mutant cell lines were resistant to transformation by transforming genes expressed under the long terminal repeat (LTR) of Moloney murine leukemia virus (Mo-MuLV). In contrast, these cell lines could be efficiently transformed by the same transforming genes with human metallothionein promoter, polyomavirus promoter-enhancer, and c-H-ras promoter. Transient expression assays using plasmids containing the CAT gene under the LTR of Mo-MuLV also showed that CAT activity expressed under the LTR in these mutant cells was lower than that in the parental cell line, No. 7. These results suggest that cellular mutations of R78 and R107 cells affect specific transcription from the LTR of Mo-MuLV. Studies using various constructs of the LTR CAT indicated that the region responsible for the repression was located in a fragment (-328 to -150) of the LTR containing the 72-bp repeat enhancer. Somatic cell hybridization experiments showed that the mutant phenotype of these mutant cell lines is dominant to that of the parental cell line.
 ...
PMID:Rat cellular mutants for expression of mRNA from the long terminal repeat of murine retrovirus. 160 5

Human T cell leukemia virus type 1 is the causative agent of adult T cell leukemia. The virus encodes a 40-kDa protein, tax, that is important for the immortalization of T cells. Expression of tax activates several cellular transcription factors, including NF kappa B. We have previously identified two functional NF kappa B binding sites within the murine c-myc gene: upstream regulatory element (URE) and internal regulatory element (IRE). Using transient cotransfection analysis of Jurkat or HeLa cells, we report that tax can transactivate chimeric TK-CAT constructs containing multiple copies of wild-type URE or IRE, but not constructs with mutated versions of these elements. Furthermore, tax induced transcriptional activity of murine and human c-myc promoter-CAT hybrid genes in Jurkat and HeLa cells. A mutated tax expression vector, which fails to activate NF kappa B, was unable to induce either murine or human c-myc-CAT or URE/IRE-TK-CAT constructs. Mutant c-myc gene-CAT constructs, in which the URE and IRE were mutated either singly or in combination by site directed mutagenesis, displayed significantly reduced CAT activation upon cotransfection with a tax expression vector. These results suggest that tax can transactivate the c-myc gene through NF kappa B. The tax-induced stimulation of this oncogene may play a role in T cell immortalization.
 ...
PMID:Transactivation of the c-myc promoter by human T cell leukemia virus type 1 tax is mediated by NF kappa B. 164 14

The hydroxyl radicals produced by two adherent cell lines, a human cancer cell and a mouse fibroblast, and six suspended human leukemia cell lines at different stages of differentiation were measured by electron spin resonance (ESR) spectrometry. The concentration of hydroxyl radicals detected in these tumor cells increased in proportion to temperature and cell number. The addition of the enzymes superoxide dismutase (SOD) and catalase (which do not permeate the cell membrane), reduced the amount of hydroxyl radicals detected. SOD decreased hydroxyl radicals somewhat but catalase eliminated hydroxyl radicals almost completely. These findings suggest that hydroxyl radicals are produced extracellularly consisted primarily of H2O2 but partially from superoxide radicals. Using the human leukemia cell lines at different stages of differentiation we demonstrated that cell differentiation may correlate with hydroxyl radical production. The earlier the stage of leukemic cell differentiation the more the greater the production of hydroxyl radicals. Moreover, the ability of SOD or catalase to eliminate hydroxyl radical activity correlated inversely with leukemic cell differentiation.
 ...
PMID:Production of hydroxyl radicals by tumor cells varies with cell type as measured by electron spin resonance spectrometry. 164 69

We reported previously that composite DNA constructed from a mammalian plasmid (L factor) and foreign gene can be reestablished as a plasmid in mouse embryonal carcinoma (F9) cells after transfection and the plasmid-bearing F9 cells undergo normal in vitro differentiation in response to retinoic acid, an inducer for F9 cell differentiation. We constructed F9 cells bearing plasmidal L factor DNA in which a reporter (chloramphenicol acetyltransferase; CAT) gene was placed under the control of a differentiation-responsive viral (Moloney murine leukemia virus or simian virus 40) enhancer-promoter. When such plasmid-bearing cells were treated with retinoic acid, the CAT gene was inducibly expressed. These results indicate that mammalian gene expression can be studied with the plasmidal expression vector which is structurally dissociated from complex chromosomes.
 ...
PMID:Induction of CAT gene expression on a plasmid vector (L factor) by retinoic acid in mouse embryonal carcinoma (F9) cells. 166 27


1 2 3 4 5 6 7 8 9 10 Next >>