Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human fetal thymuses were obtained from abortuses of HIV-1 seronegative females. Thymocytes were isolated and cultured for 2 days with PHA. Thereafter, the culture was divided and half of the cells were exposed to the HIV-1 RF isolate for 4 h. After this incubation period, the HIV-1 exposed and nonexposed control cells were cultured in RPMI 1640 supplemented with IL-2 for 30 days and subsequently maintained in RPMI without the addition of growth factors. Long term culture of both HIV-1 exposed and control thymocytes has yielded two cell lines that have been maintained for more than 3 yr without the addition of growth factors. Flow cytometry using mAb that recognize T cell differentiation markers was used to analyze cell phenotypes. The HIV-1 exposed thymocyte cell line (E88/RF) was shown to be HIV-1 infected by p24 ELISA, reverse transcriptase activity, immunocytochemistry, in situ hybridization, polymerase chain reaction, electron microscopy, and to produce infectious particles by a syncytial forming assay. The non-HIV-1-exposed thymocyte cell line (T412) has remained negative by all criteria for HIV-1 infection. Flow cytometry showed the T412 cells to be positive for the T cell markers CD45, CD38, and CD4 but negative for all other markers tested. The E88/RF cells are positive for CD45 and CD38 but negative for CD4 and other markers. These data report the isolation of two human fetal thymocyte cell lines; one uninfected and susceptible to HIV-1 infection, and the other persistently and productively infected with HIV-1 with little cytopathology. These findings suggest that HIV-1 can persistently infect early T cells and may alter T cell differentiation.
...
PMID:Persistent productive HIV-1 infection of a CD4- human fetal thymocyte line. 137 48

Cultured BALB/c epidermal Langerhans cells express high levels of the costimulatory molecule B7 on their surfaces relative to levels expressed on fresh Langerhans cells. Quantitation of relative amounts of B7 mRNA in fresh epidermal cells and cultured epidermal cells following amplification of mRNA signals via reverse transcriptase-polymerase chain reaction, hybridization of PCR products with radiolabeled internal oligonucleotide probes, resolution of hybrids in non-denaturing polyacrylamide gels, and detection by autoradiography revealed dramatically (approximately one thousandfold) higher levels of B7 mRNA in cultured epidermal cells (10-40% I-A+) as compared with fresh epidermal cells (1-4% I-A+). Levels of B7 mRNA in cultured epidermal cells were also substantially greater than those detected in a reference B lymphoma cell line (CH-1). Analysis of B7 mRNA expression in subpopulations of cultured epidermal cells demonstrated that essentially all of the B7 mRNA was present in Langerhans cells; cells bearing I-A and CD45 antigens. Cultured keratinocytes did not contain appreciable amounts of B7 mRNA. These results are consistent with previous data regarding surface expression of B7 by cLC and also demonstrate that fLC are essentially devoid of B7 mRNA and surface protein.
...
PMID:Regulation of expression of B7 by murine Langerhans cells: a direct relationship between B7 mRNA levels and the level of surface expression of B7 by Langerhans cells. 750 29

Cytokine mRNA expression was analyzed by reverse transcriptase (RT)/PCR in extensively purified normal peripheral CD4+CD45R T cell subsets. Both CD45RA+ and CD45 RO+ populations produced mRNAs for interleukin (IL)-2, IL-2 receptor (alpha chain), IL-6 receptor and tumour necrosis factor (TNF)-beta within 3-4 h of activation. Whilst IL-3 and RANTES were also expressed in both subsets, CD45RO+ cells were clearly the major producers of these cytokines. In contrast, mRNA transcripts for IL-1 alpha, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and the T cell receptor for IL-1 were almost exclusively induced in CD45RO+ T cells. A population of CD4+ T cells co-expressing intermediate levels of both CD45RA and CD45RO, namely CD45RA+/CD45RO+, appeared to be the major producers of IL-6. Addition of cycloheximide (CHx) 4 h after T cell activation resulted in substantial superinduction of IL-2 mRNA in the CD4+CD45RO+ population but had little effect on CD4+CD45RA+ cells. Taken together, these results show that normal CD4+CD45R T cell subsets exhibit distinct cytokine mRNA profiles and that these differ from the patterns displayed by Th1 and Th2 type T helper clones. Furthermore, they suggest for the first time that IL-2 mRNA turnover is differentially regulated in CD45R T cell subsets.
...
PMID:Differential expression and regulation of cytokine mRNAs in normal human CD45R T cell subsets. 751 60

Successful expression of the TCR beta-chain gene is a multistep process that involves: 1) initial transcription of multiple, unrearranged gene segments, 2) rearrangement of V, D, and J gene segments to form a complete beta-chain gene, and 3) transcription of the fully rearranged beta gene. All of these events have been shown to occur in the thymus, where the majority of T cell development takes place; however, the extent to which any of these events may occur prethymically has not been established. To examine prethymic TCR-beta gene expression, RNA was isolated from a precursor T cell-enriched population (Thy 1low CD3-) of C58/J mouse bone marrow, and analyzed by reverse transcriptase-PCR. A transcript containing TCR-beta constant (C) region sequences but not variable (V) region sequences was amplified, suggesting that an unrearranged TCR-beta gene locus is transcriptionally active in this bone marrow population. The same product was detected in Thy 1+ CD3- bone marrow cells from nude mice, indicating that the thymic microenvironment is not necessary for initiation of TCR-beta gene transcription. This C beta transcript is not confined to pre-B cells, as it was identified in RNA isolated from Thy 1low CD3- B220- bone marrow cells. Germline V beta transcripts were also detected in RNA from this bone marrow population. Furthermore, Sca-1+ Lin- and Sca-1+ Lin+ bone marrow populations from both C58/J mice and nude mice also expressed the C beta transcript. DNA-PCR analyses with D beta-J beta primer sets revealed that partial rearrangement of the beta locus had occurred in all bone marrow populations analyzed. These data suggest that both transcription and partial rearrangement of the TCR-beta locus can initiate in bone marrow cells of adult mice, before exposure of these cells to the thymus.
...
PMID:Transcription of the TCR-beta locus initiates in adult murine bone marrow. 770 28

The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells.
...
PMID:TNF-alpha expression by resident microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines. 781 94

Trophoblasts have been detected in uterine venous blood, lung parenchyma and maternal blood in the first trimester. Their dilution within maternal leukocytes has been recently estimated to be 1:10(-6). The objectives of this study were to enrich peripheral maternal blood preparations for trophoblast cells, to isolate trophoblasts from the enriched preparation by highly specific markers and to assess fetal cell total number of chromosomal copies by fluorescence in-situ hybridization (FISH). Negative and positive selections for trophoblasts were performed. To assess the efficacy of the enrichment methods, a model mimicking the in-vivo conditions was established. Purified first trimester trophoblasts were prepared from first trimester placentas and were mixed with leukocytes from non-pregnant women in various concentrations. Magnetic beads coupled with antibodies to the common leukocyte antigen (CD45) or to antitrophoblast specific antigens (Trop1, Trop2 and GB25), were attached to peripheral maternal blood cells or to the prepared mixed cell populations. The expression of alpha human chorionic gonadotrophin (alpha HCG) or of human placental lactogen (HPL) by the remaining cells was examined by two means: (i) immunocytochemistry, using monoclonal antibodies against HPL and alpha HCG to stain fetal cells; (ii) reverse transcriptase polymerase chain reaction (RT-PCR), using specific primers for exons of the HPL or alpha HCG mRNAs. Results revealed that HPL- and alpha HCG-expressing cells could be identified in maternal blood only in very rare instances. On the other hand, expression of alpha HCG and HPL by only 100 purified first trimester trophoblasts artificially mixed with peripheral leukocytes at a ratio of 1:10(-5) could be identified by both immunocytochemistry and RT-PCR.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Trophoblasts circulating in maternal blood as candidates for prenatal genetic evaluation. 796 99

Suramin has long been used for the treatment of Gambian and Rhodesian trypanosomiasis and oncocerciasis. More recently, the demonstration that suramin inhibits DNA polymerases, reverse transcriptase and the lymphocyte terminal deoxynucleotidyl transferase has led to its clinical trials for the treatment of AIDS and cancer. The precise nature of suramin's anti-neoplastic action is not clear at this time. Suramin rapidly alters the tyrosine-specific phosphorylation of cellular proteins in many cancer cell lines. Here we demonstrate that suramin strongly inhibits the activity of CD45, the principal tyrosine specific protein phosphatase of T lymphocytes. Suramin-induced inactivation of CD45 is noncompetitive, irreversible and complete within 10 min. The ability of suramin to block CD45 mediated phosphatase function provides both new insight into the mechanism of action of this agent and a useful new probe for studies of T cell activation.
...
PMID:Suramin, an experimental chemotherapeutic drug, irreversibly blocks T cell CD45-protein tyrosine phosphatase in vitro. 833 52

The syndecans comprise a family of integral membrane proteoglycans that regulate cell behaviors by binding to extracellular matrix and binding growth factors. In mouse blood cells, syndecan expression is restricted to cells of the B-cell lineage where it is expressed by pre-B cells and plasma cells, but is absent from circulating B cells. In the present study, we examined the expression, structure, and function of syndecan on human myeloma cell lines and myeloma patient bone marrow cells. On myeloma cells, syndecan is a small (modal relative molecular mass [M(r)] = 120 Kd) heparan sulfate proteoglycan localized at the cell surface. Syndecan was detected by immunodot blotting on 7 of 10 human myeloma cell lines and by reverse transcriptase polymerase chain reaction on 10 of 14 patient samples. Cell binding assays show that myeloma cells expressing syndecan bind to type I collagen via heparan sulfate chains, while those cell lines not expressing syndecan do not bind to collagen. Furthermore, the cell lines expressing syndecan were negative for CD19 and CD45 staining, indicating that syndecan expression is restricted to tumors having a well-differentiated phenotype. We conclude that syndecan acts as a matrix receptor on human myeloma cells but is not expressed by all tumors, suggesting that syndecan may participate in regulating myeloma cell adhesion to the bone marrow stromal matrix.
...
PMID:Expression of syndecan regulates human myeloma plasma cell adhesion to type I collagen. 842 68

In utero transplantation of preimmune fetal sheep with human hematopoietic stem cells results in stable long-term hematopoietic chimerism. To clarify the mechanisms of support of human stem cells in chimeric sheep, we established stromas from bone marrow of 30 sheep transplanted in utero with human hematopoietic stem cells from adult bone marrow adult peripheral blood, or fetal liver. We examined the stromas for the presence or absence of human stromal elements in vitro. Human stromal elements were detected in 12 sheep as assessed by polymerase chain reaction (PCR) using human HLA-DQalpha-specific primers. The human origin of the PCR product was confirmed by Southern blotting using an HLA-DQalpha-specific probe. However, none of these stromal cells were positive for CD45 or CD14 as determined by fluorescence-activated cell sorting (FACS) analysis or by message expression using reverse transcriptase (RT)-PCR. In an attempt to further characterize these cells fibroblasts were isolated by panning, and DNA analysis confirmed the human origin of these cells in the same lambs. Of the fetuses injected with the highly enriched cells from adult human bone marrow 36% were found to harbor cells capable of forming human stromal elements in vitro in their marrow. Of those injected with human fetal liver and peripheral blood stem cells, 42 and 40%, respectively, exhibited in vitro human stromal cell-forming ability. These results indicate the long-term persistence of cells capable of giving rise to components of human marrow stroma in vitro in the human/sheep xenograft model.
...
PMID:Detection of human cells in human/sheep chimeric lambs with in vitro human stroma-forming potential. 859 79

This study compares the histologic and immunophenotypic features of 71 cases of primary CD30+ diffuse large-cell lymphomas (DLCL) and 128 cases of Hodgkin's disease (HD) and discusses the clinical features of 52 patients with CD30+ DLCL. It includes analysis of sites of involvement, staging, response to treatment, sites and treatment of recurrences, and disease-free and overall survival. Diagnostic immunophenotypic differences were found between CD30+ DLCL and HD. All cases of CD30+ DLCL were positive for one or more common or lineage-specific lymphocyte antigens or for EMA. In contrast, 96.9% of HD cases were negative for CD45, CD45-RO, CD43, and CD20. The four exceptions are discussed. All cases of HD were negative for EMA. In patients with CD30+ DLCL, a T-cell phenotype was found in 60%, a null-cell type in 22%, and a B-cell type in 18% of the cases. The median age of patients with T- and null-cell phenotype was 22 years (range, 4 to 72). Fifty-two percent of them had high-stage (III and IV) disease and 61% had extranodal involvement at presentation, including 25% with skin lesions. Lymph nodes draining the skin lesions became involved in seven of 11 patients. No patient had initial bone marrow involvement. Most patients were treated with chemotherapy, and 83% had a complete remission. Fifty-four percent remain free of disease with a median follow-up of 47 months. Thirteen patients (29%) had one or more recurrences and five of them remain free of disease after salvage therapy, with a median follow-up period of 79 months. The clinical stage did not affect survival, probably as a result of different therapy. The t(2;5) translocation was found in five of 15 patients who had cytogenetic abnormalities. Of the other 10 cases, the translocation was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in four of five cases studied. All nine cases were of T- or null-cell phenotype. The cases of B-cell CD30+ DLCL had a characteristic immunophenotype. All were negative for EMA. These patients were older and had frequent bone marrow involvement but no skin infiltration by lymphoma. All three patients who were human immunodeficiency virus-positive (HIV+) had lymphomas of B-cell lineage. Detection of the t(2;5) translocation by molecular genetics is a useful and highly specific marker in the differential diagnosis between HD and CD30+ DLCL.
...
PMID:CD30 (Ki-1)-positive malignant lymphomas: clinical, immunophenotypic, histologic, and genetic characteristics and differences with Hodgkin's disease. 863 11


1 2 3 4 5 Next >>

---