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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An animal leukemia model was developed to investigate in vivo induction of differentiation of myeloid leukemia cells. An aneuploid cell line (C15) was isolated from mouse myelomonocytic leukemia WEHI-3B D+ cells. The C15 cells contained twice as much DNA as the parental cells but retained the morphology of myelomonocytic cells and the ability to differentiate into macrophage-like cells in response to all-trans retinoic acid (ATRA) in vitro. When the C15 cells were inoculated into the peritoneal cavity of syngeneic Balb/c mice (10(6) cells/mouse), the mice died of leukemia within 19 days. The DNA content and differentiation antigen (Mac-1) of the cells in the peritoneal cavity were determined by dual-parameter flow cytometry. On day 12 after inoculation, the C15 cells were distinguishable from normal host cells in the peritoneal cavity by their different DNA content. The administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) (10 micrograms/day) to mice bearing C15 cells induced the leukemia cells to express Mac-1 antigen and to change morphologically into mature granulocytic cells. Because the C15 cells were not responsive to G-CSF in suspension culture in vitro, this result suggests that the cytokine's actions on the cells in vivo and in vitro are different. This experimental model for analyzing in vivo differentiation of leukemia cells will be useful for studying the therapeutic effects of potential differentiation-inducing agents.
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PMID:Flow-cytometric analysis of in vivo induction of differentiation of WEHI-3B myelomonocytic leukemia cells by recombinant granulocyte colony-stimulating factor. 751 48

Mice infected with the Duplan strain of murine leukaemia virus (Dup MuLV), a retrovirus, develop a syndrome sharing several features with AIDS, including lymphadenopathy and profound immunodeficiency. We measured the changes in peripheral blood lymphocyte populations and evaluated their predictive value for the outcome of disease in C57Bl/6 mice. Animals were inoculated with Dup MuLV (SC1/Dup MuLV confluent fibroblast supernatant or spleen extract from an infected mouse). Peripheral blood lymphocyte subsets were sequentially monitored for 73 days using flow cytometric analysis and MoAbs directly conjugated to fluorochromes. A striking fall in the Thy1.2+ cell count occurred in diseased animals, mostly affecting the CD8+ cell compartment. At the same time, the percentage of Ly5+ cells was increased. Mice were killed at day 73 and spleen and lymph node lymphocytes were analysed. Phenotypic lymphocyte modifications in peripheral blood were closely related to those in the spleen or lymph nodes. Analysis of Ly6c antigen expression on CD4+ and CD8+ cells showed a selective expansion of the CD8+Ly6c+ subset, which may reflect a state of immune activation. Our results suggest that phenotypic alterations of peripheral blood lymphocytes are a good marker of disease progression in this model and could be a useful criterion to evaluate antiretroviral therapy.
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PMID:Prognostic value of phenotypic alterations in blood lymphocyte subsets in a murine retrovirus-induced immunodeficiency syndrome (MAIDS). 809 94

We have used a biological test on the microplates of cellular cultures in order to investigate the toxicity and the antiviral properties against different viruses: defective Moloney Murine Leukemia virus (MoMLV) derived from the SVX shuttle and expressing resistance to the G418 antimitotic, and Human Immunodeficiency Virus (HIV) of a hydroalcoholic extract from Haemanthus albiflos (Amaryllidacae). The toxicity was assessed through coloric test evaluation of fixed cells stained with crystal violet. In a population of NIH 3T3 cells (Fibroblasts mouse), the toxicity found with 2, 7, 14 and 28 microliters/ml of lyophilisat extract corresponding at: 0.23, 0.81, 1.62 and 3.24 mg of plant dry, was 32, 50, 63 and 70% respectively. With regards to the antiviral properties, the plant extracts showed an inhibition of 88% on the formation of G418 resistant 3T3 clones. The assay on HIV infected lymphotic cells (P4) showed an IC50 of 4 microliters/ml for this extract plant. Therefore, the toxic effect was similar to the antiviral response.
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PMID:[Antiviral activity of hydroalcoholic extract from Haemanthus albiflos on the Moloney murine leukemia virus and the human immunodeficiency virus]. 929 69

Hybrid (C56BL/6 x DBA) (BDF1; H-2b/H-2d) mice bearing the P815 leukemia (H-2d) were grafted with a (CBA x C57BL/6)F1 (CBF1; H-2k/H-2b) cell suspension, comprising bone marrow cells (BMC; 25 x 10(6)/mouse) and spleen cells (SC; 55 x 10(6)/mouse) on day-4, then treated with cyclophosphamide (200 mg/kg) on day-2 and finally grafted once more with CBF1 cells (25 x 10(6) BMC + 7 x 10(6) SC) on day 0. Allogeneic cell graftings performed in this way induced durable mixed hematopoietic chimerism and significantly prolonged the survival of recipients, compared with that of leukemia-bearers grafted with syngeneic cells. The results obtained raise the possibility of using allogeneic hematopoietic tissue transplantation in combination with non-lethal cytoreductive therapy to induce a long-lasting graft-vs-leukemia effect.
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PMID:Induction of mixed allogeneic chimerism for leukemia. 940

Leukemia is an acquired genetic disease caused by the accumulation of chromosomal abnormalities which modify either the biochemical property or the level of expression of proteins. Frequent genetic abnormalities identified in human leukemia are chromosomal rearrangements such as chromosomal translocations and inversions. Chromosome band 3q26 is the site of the breakpoint of recurring translocations and inversions observed in patients with myeloid leukemias. Two genes located at 3q26 have been implicated in development or progression of myeloid leukemia. They are MDS1 and EVI1. MDS1, first identified as part of a fusion transcript resulting from the t(3;21)(q26;q22), encodes a small protein of unknown function. EVI1 encodes a zinc finger protein inappropriately overexpressed by chromosomal rearrangements (in man) or by retroviral insertion (in the mouse). Both genes are rearranged by the t(3;21)(q26;q22) and by the t(3;12)(p13;q22). As a result of the translocation, they are expressed as fusion genes either with AML1 or with TEL. EVI1 and MDS1 are unusual in that they can either encode separate proteins, or they can be expressed as one protein which we named MDS1/EVI1. EVI1 and MDS1/EVI1 have opposite functions as transcription factors. In this report, we review the current information on the two genes, and on their involvement in myeloid leukemia.
Leukemia 1997 Dec
PMID:The EVI1 gene in myeloid leukemia. 944 15

Penidiamide, a new tripetide containing dehydrotryptamine, glycine and anthranilic acid linked together by two amide bonds, and oxindole were isolated from submerged cultures of Penicillium sp. 62-92. Both compounds preferentially inhibited human synovial phospholipase A2, penidiamide with an IC50 of 30 microM and oxindole of 380 microM. With the exception of U 937 cells (leukemia, human), no cytotoxic activities were detected against HL-60- (leukemia, human), HeLa S3- (epitheloid carcinoma, human), BHK 21- (kidney fibroblasts, hamster), and L1210-cells (leukemia, mouse). No antimicrobial activity was detected for oxindole, and only weak antibacterial activity for penidiamide. The structure of penidiamide was elucidated by spectroscopic methods.
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PMID:A new inhibitor of synovial phospholipase A2 from fermentations of Penicillium sp. 62-92. 952 22

An immunodetection technique has been developed to map with high resolution the methylated sites of human chromosomes. We have used this method to define the methylated areas of chromosomes from normal donors and from leukemia cell lines. The chromosomes were exposed for a short time to UV light to induce mild denaturation. The methylated sites were detected in situ by using monoclonal antibodies against 5-methylcytosine (prepared in mouse), and fluorescein-conjugated antimouse immunoglobulins. The chromosomes from normal cells exhibited a fluorescent pattern with RCT banding, although some differences from previously reported patterns could be detected. With this method we have been able to show the presence of two types of R-bands: High fluorescence R-band (HFR) and low fluorescence R-band (LFR). Chromosomes from leukemia cell lines exhibited low global staining with disrupted RCT banding of the chromosomes. The decreased level of the methylation status of the chromosomes from leukemia cells was confirmed by detection of 5-methylcytosines on total immobilized DNA. Thus, we have shown that this method can be used to determine the methylated status of chromosomes and, in turn, to map not only the structural (banding) but also the functional (methylation status) properties of the different chromosome domains in normal and pathologic human cells.
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PMID:Altered patterns of DNA methylation on chromosomes from leukemia cell lines: identification of 5-methylcytosines by indirect immunodetection. 961 7

As pituitary leukemia-inhibitory factor (LIF) mediates neuroimmune signals to the hypothalamo-pituitary-adrenal axis, we tested the role of intracellular SOCS-3 in corticotroph function. SOCS-3, a cytokine-inducible protein of the suppressor of cytokine signaling (SOCS) family, is expressed in the murine pituitary in vivo. After i.p. injection of LIF (5.0 micrograms/mouse) or interleukin-1 beta (0.1 microgram/mouse) pituitary SOCS-3 mRNA was stimulated 9-fold and 6-fold, respectively. Also, in corticotroph AtT-20 cells LIF and interleukin-1 beta both potently stimulated SOCS-3 mRNA expression. In AtT-20 cells, stable overexpression of SOCS-3 inhibits basal and LIF-stimulated ACTH secretion in comparison to mock-transfected AtT-20 cells (basal: 4426 +/- 118 vs. 4973 +/- 138 pg/ml, P < 0.05; LIF-induced: 5511 +/- 172 vs. 9308 +/- 465 pg/ml, P < 0.001). Stable overexpression of SOCS-3 cDNA in AtT-20 cells also resulted in a significant 50% decrease of LIF-induced POMC mRNA levels (P < 0.05) and POMC promoter activity (P < 0.001), respectively. Western blot analysis revealed an inhibition of LIF-stimulated gp130 and STAT-3 phosphorylation in SOCS-3 overexpressing AtT-20 cells. Thus, SOCS-3 inhibits the Janus kinase (JAK) and signal transducers and activators of transcription (STAT) pathway, which is known to mediate LIF-stimulated ACTH secretion and POMC gene expression. In conclusion, SOCS-3 functions as an intracellular regulator of POMC gene expression and ACTH secretion, acting as a negative feedback mediator of the cytokine-mediated neuro-immuno-endocrine interface.
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PMID:Pituitary corticotroph SOCS-3: novel intracellular regulation of leukemia-inhibitory factor-mediated proopiomelanocortin gene expression and adrenocorticotropin secretion. 965

Human T-cell leukaemia virus type I (HTLV-I)-transformed rabbit T-cells, F647a, were intraperitoneally injected into eight 10-week-old C3H/He and C3H/HeJ mice (1 x 10(7) F647a cells/mouse), respectively. Antibody titres against HTLV-I increased to a peak at 1-3 months after injection in both C3H/He and C3H/HeJ mice. At 12 months after injection, antibody titres of two of the eight C3H/HeJ mice became undetectable, whereas those of all the C3H/He mice still ranged from 1:10 to 1:40. Sera from both seropositive C3H/He and C3H/HeJ mice reacted with HTLV-I core proteins, but not with the env protein. HTLV-I proviral sequences were detected in two of eight C3H/He mice and three of the eight C3H/HeJ mice. These results suggest that HTLV-I is able to infect an adult mouse.
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PMID:Transmission of human T-cell leukaemia virus type I into adult mice. 1107 67

Caulobacter crescentus is a gram negative, non-pathogenic bacterium, common in aquatic and soil environments. One feature of note is a protein surface layer (S-layer) composed of a single protein, organized as a self-assembled crystalline array that coats the bacterium. In the course of efforts to express cancer-associated peptides as genetic insertions into the S-layer, we noted a tumor suppressive effect of the unmodified bacterium. C. crescentus was examined for anti-tumor activity against three transplantable tumor mouse models: Lewis lung carcinoma cells transfected with the MUC1 gene in C57BL/6, murine mammary carcinoma (EMT-6) in BALB/c (both in prophylactic and therapeutic mode) and murine leukemia cells (L1210) in DBA2. Mice were immunized three times i.p. with C. crescentus (2 x 10(7) cells/mouse). In prophylactic mode, the mice were challenged with tumor cells two weeks after the last immunization. Immunization with live C. crescentus resulted in anti-tumor activity in all three transplantable tumor models, as measured by prolonged survival, reduced tumor mass or reduced number of lung nodules, compared to saline control groups. In the Lewis lung and the EMT-6 mammary carcinoma murine models the number of lung nodules as well as the tumor weight was lower in mice treated with C. crescentus, compared to the control group; for EMT-6, this was observed in prophylactic and therapeutic modes. In the murine leukemia and Lewis lung carcinoma models prolonged survival was observed in the groups of mice immunized with Caulobacters. In most cases the live C. crescentus cells were markedly more efficacious than heat killed or formalin fixed cells, despite the fact that they do not grow or persist in mice. The results suggest that C. crescentus may be a safe, bacterial immunomodulator for the treatment of tumors.
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PMID:Anti-tumor effects of the bacterium Caulobacter crescentus in murine tumor models. 1658 92


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