Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002874 (aplastic anemia)
 5,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ten post-weanling 4-month-old cats, designated "tracers", were placed in a feline leukemia cluster household to determine the efficiency of horizontal transmission of feline leukemia virus (FeLV). The tracer cats were confirmed as negative for prior exposure to FeLV. Following the placement in the leukemia cluster environment, the tracer cats were serologically monitored at intervals of 3-6 weeks for a total period of 1 year. The tests employed included the detection of FeLV using fixed-cell immunofluorescence and the detection and titration of antibody to : (1) the feline oncornavirus-associated cell membrane antigen (FOCMA), as detected by membrane immunofluorescence; (2) viable FeLV, using serum neutralization; (3) virion core protein p30, using radioimmunoprecipitation; and (4) virion glycoprotein gp70, using radioimmunoprecipitation. All of the tracers had evidence of horizontal infection by FeLV, by several criteria. Seven of the 10 had virus that could be isolated from plasma. All of these 7 developed a terminal illness within 18 months; 3 developed aplastic anemia, 3 infectious peritonitis, and 1 lymphoma. The remaining 3 were negative for FeLV by both virus isolation and fixed-cell immunofluorescence. These 3 did, however, develop high antibody titers by all four criteria and they remained healthy throughout the examination period. These results clearly indicate that unprotected pros-weanling cats brought into a leukemia exposure household environment have a high risk of becoming infected with FeLV. Furthermore, a large proportion of the cats are at risk for development of persistent viremia and FeLV-related diseases.
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PMID:Horizontal transmission of feline leukemia virus under natural conditions in a feline leukemia cluster household. 18 73

Feline leukemia viruses (FeLVs) belonging to the C subgroup induce aplastic anemia in domestic cats and have the ability, unique among FeLV strains, to proliferate in guinea pig fibroblasts in tissue culture. Previous studies have shown that the pathogenic and host range specificity of a prototype molecular clone of FeLV-C [FeLV-Sarma-C (FSC)] colocalize to a region encoding the 3' 73 amino acids of the pol gene product and the N-terminal 241 amino acids of the envelope surface glycoprotein named SU. Here, we amplified, via PCR, cloned, and sequenced the SU coding sequence from three additional anemia-inducing subgroup C FeLV isolates. Chimeric viruses were constructed by replacement of fragments of FeLV-C envelope genes into the FeLV-A prototype virus 61E. Using a modified vesicular stomatitis virus-FeLV pseudotype assay, we demonstrated that the subgroup C receptor specificity for each virus was determined by changes within the N-terminal 87-92 amino acids of SU, in which most changes occurred within the 15- to 20-amino-acid first variable region (V1). Determinants for growth in guinea pig cells colocalized to this region. Despite the consistent localization of biological determinants, the only consistent features that distinguished the deduced FeLV-A and FeLV-C proteins was one lysine-to-arginine change and a structural prediction of an alpha-helix in FeLV-A proteins versus random coil in FeLV-C proteins within V1. However, arginine in equilibrium with lysine substitutions were not sufficient to convert the subgroup A virus to the subgroup C phenotype or vice versa. Thus, certain distinct structural changes within the N-terminal region of FeLV SU can result in convergent viral phenotypes.
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PMID:Feline leukemia virus subgroup C phenotype evolves through distinct alterations near the N terminus of the envelope surface glycoprotein. 132 57

Feline leukemia virus is a naturally occurring, contagiously transmitted and oncogenic immunosuppressive retrovirus of cats. The effects of FeLV are paradoxical, causing cytoproliferative and cytosuppressive disease (eg, lymphoma and myeloproliferative disorders vs immunodeficiency and myelosuppressive disorders). In the first few weeks after virus exposure, interactions between FeLV and hemolymphatic system cells determine whether the virus or the cat will dominate in the host/virus relationship--persistent viremia and progressive infection or self limiting, regressive infection will develop. The outcome of these early host/virus interactions is revealed in the diagnostic assays for FeLV antigenemia and viremia. The latter, in turn, predict the outcome of FeLV infection in cats. Known host resistance factors include age and immune system functional status. Known virus virulence factors are magnitude of exposure and virus genotype. Molecular analysis of FeLV strains indicated that natural virus isolates exist as mixtures of closely related virus genotypes and that minor genetic variations among FeLV strains can impart major differences in pathogenicity. The genetic coding regions responsible for cell targeting and specific disease inducing capacity (eg, thymic lymphoma, acute immunosuppression, or aplastic anemia) have been mapped to the virus surface glycoprotein and/or long terminal repeat regions for several FeLV strains. Infection by specific FeLV strains leads to either malignant transformation or cytopathic deletion of specific lymphocyte and hemopoietic cell population, changes that prefigure the onset of clinical illness. Another notable feature of the biology of FeLV is that many cats are able to effectively contain and terminate viral replication, an important example of host immunologic control of a retrovirus infection and a process that can be selectively enhanced by vaccination. Thus, FeLV infection serves as a natural model of the multifaceted pathogenesis of retroviruses and as a paradigm for immunoprophylaxis against an immunosuppressive leukemogenic retrovirus.
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PMID:Feline leukemia virus infection and diseases. 166 70

Recombinant granulocyte colony-stimulating factor (rG-CSF) is a glycoprotein hormone which has been produced in mammalian cells and, in a nonglycosylated form, in the bacterium Escherichia coli through recombinant DNA technology. It stimulates proliferation, differentiation and activation of cells of the neutrophil-granulocyte lineage and has been investigated as therapy for patients with various neutropenic conditions, both iatrogenic and disease related. rG-CSF is well tolerated, the most frequently reported adverse effect being mild to moderate bone pain. A major use for rG-CSF therapy will be in ameliorating the neutropenia which follows cytoreductive chemotherapy. rG-CSF accelerates neutrophil recovery after chemotherapy, leading to a reduction in duration of the neutropenic phase. Consequently, infection rate is diminished, as is the associated usage of antibiotics and duration of hospitalisation. The implications are that rG-CSF may allow increased dose intensity and stricter adherence to chemotherapy schedules. The increase in neutrophils produced by rG-CSF renders it a useful treatment for conditions such as congenital, acquired and cyclic neutropenias for which current therapy is not very successful. rG-CSF may be an effective therapy in myelodysplasia, although there is concern about acceleration of the possible rate of conversion of this disease to acute myelogenous leukaemia. It is also likely that rG-CSF will be useful in accelerating the recovery of transplanted bone marrow in patients with leukaemia, lymphoma and solid tumour. Furthermore, there is great potential for expansion of the role of rG-CSF as monotherapy or in combination regimens with other cell factors in various haematological disorders such as aplastic anaemia. In summary, while many aspects of its use remain to be clarified, rG-CSF must be seen as an exciting advance in therapeutics. It should rapidly find an important place as an adjunct to cancer chemotherapy, and also appears to have substantial potential in a number of other neutropenic conditions which are currently difficult to treat.
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PMID:Recombinant granulocyte colony-stimulating factor (rG-CSF). A review of its pharmacological properties and prospective role in neutropenic conditions. 171 26

Interleukin-3 (IL-3) is a glycoprotein belonging to the hematopoietic growth factor family that in preclinical in vitro and in vivo studies has exhibited a multilineage activity. Phase I/II trials with recombinant human IL-3 (rhIL-3) expressed in yeast are being done in patients with advanced malignancies as well as in patients with bone marrow failure states. Subcutaneous administration of rhIL-3 at dosages between 30 and 500 micrograms/m2 for 15 consecutive days has resulted in a dose-dependent increase in platelet counts as well as in a substantial increase in the number of circulating neutrophils, eosinophils, monocytes, and lymphocytes in patients with advanced malignancies but normal hematopoiesis. Erythropoiesis is less stimulated with an increase in hemoglobin concentration only in a minority of patients. In patients with secondary hematopoietic failure due to prolonged chemo-/radiotherapy or bone marrow infiltration by tumor cells, treatment with rhIL-3 leads to a clinically significant restoration of hematopoiesis, especially of thrombopoiesis and granulopoiesis. rhIL-3 has also been shown to improve neutrophil and platelet counts in patients with myelodysplastic syndromes, while improvement of hematopoiesis is rarely observed in patients with severe aplastic anemia with the presently used treatment schedules. Adverse effects of rhIL-3 are minor at the clinically used dosages and include fever, bone pain, headache, and stiffness of the neck. Transient thrombocytopenia has been observed in a few patients with myelodysplastic syndrome or aplastic anemia treated at dosages of 250-500 micrograms/m2. rhIL-3 is a multilineage hematopoietic cytokine with promising effects on platelet and neutrophil counts and special usefulness in patients with secondary hematopoietic failure.
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PMID:Clinical effects of recombinant human interleukin-3. 204 66

The colony-stimulating factors (CSF) are a class of glycoprotein hormones that regulate the production and function of blood cells. Human sequences encoding four of the factors active on myeloid cells--granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), and interleukin-3 (IL-3)--have been molecularly cloned and the biosynthetic (recombinant) products introduced into clinical trials. Sufficient clinical data have accumulated regarding G-CSF and GM-CSF to allow insight into their potential use in clinical practice. Both molecules have shown some impact in the prevention of chemotherapy-induced neutropenia and in the treatment of cytopenias associated with myelodysplastic syndromes and aplastic anemia. G-CSF has shown promise in the treatment of congenital and idiopathic neutropenias.
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PMID:The colony-stimulating factors: biology and clinical use. 214 19

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a 23-kDa glycoprotein with remarkably diverse effects on immune and nonimmune cells. GM-CSF induces differentiation of granulocyte, macrophage, and eosinophil precursor cells. Proliferation of monocyte-macrophages, T lymphocytes, keratinocytes, and endothelial cells is also stimulated by GM-CSF. In addition, GM-CSF alters the functional properties of mature granulocytes, macrophages, eosinophils, and basophils. GM-CSF is produced by T lymphocytes, macrophages, and several cell types in extramedullary sites, where it may act in a paracrine manner to regulate the local response to antigenic challenge. Clinical trials of GM-CSF have been conducted in patients with AIDS, aplastic anemia, myelodysplastic syndromes, and sarcoma and following bone marrow transplantation and accidental radiation exposure. GM-CSF significantly increased circulating numbers of several myeloid cells and produced dose-dependent toxicity consisting primarily of myalgias, fever, fluid retention, and serosal effusions. Additional studies are needed to define the role of GM-CSF in treatment of patients with qualitative and quantitative dysfunction of immune cells.
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PMID:Granulocyte-macrophage colony-stimulating factor: pleiotropic cytokine with potential clinical usefulness. 240 68

Aplastic anemia serum (AAS) contains humoral factors that alter both proliferation and maturation of human megakaryocytes (MK). The ability of AAS to augment MK colony formation (colony-forming unit, CFU-MK) was neutralized by an antiserum against MK colony-stimulating factor (MK-CSF), a glycoprotein isolated from AAS. The adsorbed AAS still retained the ability to accelerate cytoplasmic maturation of recognizable MK. Similar experiments were done with thrombocytopoiesis-stimulating factor (TSF) and an anti-TSF antiserum to further define the activity in AAS responsible for accelerating cytoplasmic maturation. Bone marrow fractions enriched for recognizable human MK, but devoid of CFU-MK, were obtained by centrifugal elutriation and placed in short-term liquid cultures. MK progressed through identifiable maturation stages (1-4) more quickly in the presence of either TSF or AAS. TSF slightly enhanced the cloning efficiencies of CFU-MK, but did not alter the number of MK in individual colonies derived from non-adherent, low-density, T-cell-depleted bone marrow. In contrast, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and crude AAS substantially augmented both MK colony formation and cells per colony. TSF also doubled the percent 35S incorporation into platelets of immunothrombocythemic mice, but stimulation was completely abolished by anti-TSF. Anti-TSF antiserum was then used to analyze the promotion of MK colony formation by cytokines. Cloning efficiencies of CFU-MK were reduced to baseline values when TSF was pretreated with anti-TSF; however, the MK colony-stimulating activity (MK-CSA) of GM-CSF, IL-3, or AAS was not altered by adsorption with anti-TSF. In contrast, the cytoplasmic maturation of recognizable MK was slower, and fewer mature stage-4 cells were present at days 1-3 in AAS adsorbed with anti-TSF than MK cultured in AAS treated with normal rabbit serum or untreated AAS. Therefore, TSF appears to be a major factor in AAS that accelerates terminal maturation of human MK. TSF primarily affects megakaryocytopoiesis by promoting MK maturation rather than enhancing CFU-MK proliferation.
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PMID:Effects of thrombocytopoiesis-stimulating factor on terminal cytoplasmic maturation of human megakaryocytes. 268 80

Colony-stimulating factors (CSFs) are a family of regulatory glycoprotein hormones that promote the proliferation and differentiation of hemopoietic progenitor cells and augment the functions of mature effector cells in vitro. The recent cloning of human genes and the availability of sufficient quantities of recombinant purified growth factors have made it possible to evaluate their therapeutic potential in cytopenic states. Initial studies with GM-CSF have demonstrated its ability to increase neutrophil, monocyte, and eosinophil counts in patients with acquired immune deficiency syndrome (AIDS), myelodysplastic syndrome (MDS), and aplastic anemia. Both GM-CSF and G-CSF reduce the duration of neutropenia following chemotherapy and accelerate hematopoietic recovery in patients undergoing intensive chemotherapy and autologous bone marrow transplantation. Studies are now ongoing to determine the optimal dose, route, schedule of administration, and long-term effects. While the appropriate settings for the use of different CSFs remain to be determined, the initial results of clinical trials are of great interest and suggest that hematopoietic growth factors will play an important role in several clinical arenas.
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PMID:Clinical applications of colony-stimulating factors. 268 11

Feline leukemia virus (FeLV) C-Sarma (or FSC) is a prototype of subgroup C FeLVs, which induce fatal aplastic anemia in outbred specific-pathogen-free (SPF) cats. FeLV C isolates also possess an extended host range in vitro, including an ability, unique among FeLVs, to replicate in guinea pig cells. To identify the viral determinants responsible for the pathogenicity and host range of FSC we constructed a series of proviral DNAs by exchanging gene fragments between FSC and FeLV-61E (or F6A), the latter of which is minimally pathogenic and whose host range in vitro is restricted to feline cells. Transfer of an 886-base-pair (bp) fragment of FSC, encompassing the codons for 73 amino acids at the 3' end of pol (the integrase/endonuclease gene) and the codons for 241 amino acids of the N-terminal portion of env [the extracellular glycoprotein (gp70) gene], into the F6A genome was sufficient to confer onto chimeric viruses the ability to induce fatal aplastic anemia in SPF cats. In contrast, no chimera lacking this sequence induced disease. When assayed in vitro, all chimeric viruses containing the 886-bp fragment of FSC acquired the ability to replicate in heterologous cells, including dog and guinea pig cells. Thus, the pathogenic and the host range determinants of the feline aplastic anemia retrovirus colocalize to a 3' pol-5' env region of the FSC genome and likely reside within a region encoding 241 amino acid residues of the N terminus of the extracellular glycoprotein.
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PMID:Pathogenic and host range determinants of the feline aplastic anemia retrovirus. 283 51


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