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

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

Tetraploidy or near-tetraploidy is a rare cytogenetic abnormality in acute myelocytic leukemia. We report here a case of acute promyelocytic leukemia that showed near-tetraploidy with double der(15)t(15;17) the leukemia relapsed. At diagnosis, cytogenetic analysis failed to reveal any karyotypic abnormality; however, a promyelocytic leukemia-retinoic acid receptor alpha (PML/RARA) fusion transcript of the bcr3-type was detected with reverse transcriptase-polymerase chain reaction analysis, and a single PML/RARA fusion signal was observed with fluorescence in situ hybridization analysis. At the first relapse, the majority of leukemic cells showed pseudodiploid karyotypes with der(15)t(15;17), as well as additional chromosomal abnormalities, and exhibited a single PML/RARA fusion signal. A small fraction of leukemic cells, however, showed near-tetraploid karyotypes with double der(15)t(15;17), as well as some additional chromosomal abnormalities in common with the pseudodiploid clones, and exhibited double PML/RARA fusion signals. At the second and third relapses, leukemic cells with near-tetraploidy and double PML/RARA fusion signals became predominant. The PML/RARA fusion transcript of the bcr3 type was also observed at each relapse. In addition, Southern blot analysis of the RARA gene at diagnosis and at the second relapse showed a common rearranged band. Notably, giant, bizarre, and hypogranular promyelocytes expressing CD2, CD34, and HLA-DR appeared at the first relapse and became predominant at the second and third relapses. These observations indicate that the APL cells with near-tetraploidy and double der(15)t(15;17) clonally evolved from the pseudodiploid leukemic cells and exhibited the bizarre morphology and aberrant surface immunophenotypes.
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PMID:Secondary near-tetraploidy with double der(15)t(15;17) in acute promyelocytic leukemia in relapse. 1503 89

Although information about the development of primitive and definitive hematopoiesis has been elucidated in murine embryos and embryonic stem (ES) cells, there have been few in vitro studies of these processes in primates. In this study, we investigated hematopoietic differentiation from cynomolgus monkey ES cells grown on OP9, a stromal cell line deficient in macrophage colony-stimulating factor. Primitive erythrocytes (EryP) and definitive erythrocytes (EryD) developed sequentially from ES cells in the culture system; this was confirmed by immunostaining and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of embryonic, fetal and adult globin genes. EryP were detected on day 8 without exogenous erythropoietin (EPO), whereas EryD appeared on day 16 and had an indispensable requirement for exogenous EPO. RT-PCR analysis of the cultures revealed a sequential expression of genes associated with primitive and definitive hematopoietic development that was equivalent to that seen during primate ontogeny in vivo. Vascular endothelial growth factor (VEGF) increased, in a dose-dependent manner, not only the number of floating hematopoietic cells, but also the number of adherent hematopoietic cell clusters containing CD34-positive immature progenitors. In colony assays, exogenous VEGF also had a dose-dependent stimulatory effect on the generation of primitive erythroid colonies. More efficient primitive and definitive erythropoiesis was induced by re-plating sorted CD34-positive cells. Thus, this system reproduces early hematopoietic development in vitro and can serve as a model for analyzing the mechanisms of hematopoietic development in primates.
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PMID:Development of primitive and definitive hematopoiesis from nonhuman primate embryonic stem cells in vitro. 1508 70

We report 3 cases of synovial sarcoma with rhabdoid features, initially diagnosed as adult rhabdoid tumors. Two women (case nos. 1 and 2, 35 years and 27 years of age, respectively) and one man (case no. 3, 26 years of age) presented to their physicians with right flank pain. On physical examination, a poorly defined, firm, palpable mass was found in the upper right quadrant of the abdomen in all cases. Sonography and computed tomography revealed solid, cystic masses in the right kidneys that ranged in size from 8.5 to 20.0 cm. Right radical nephrectomies were performed in all patients. One patient died of disease, and the other two patients were alive and disease-free after chemotherapy and radiotherapy. Microscopic examination revealed that the tumors were composed mostly of rhabdoid cells with eccentrically located nuclei, prominent nucleoli, and eosinophilic cytoplasm. We also found areas of fasciculated spindle cells, sharply separated from or irregularly admixed with areas of rhabdoid cells. There was tumor necrosis, but no epithelial areas were seen. Hemangiopericytic vasculature was at least focally observed in all cases. The tumor cells were positive for CD99 and bcl-2 in all cases and for CD56 in two cases and negative for CD34 and smooth muscle actin in all cases. The cells in case no. 1 were focally positive for cytokeratin. To verify the possibility of synovial sarcoma with rhabdoid features, reverse transcriptase polymerase chain reaction using RNA extracted from frozen tissue in case no. 1 and formalin-fixed, paraffin-embedded tissue in case nos. 2 and 3 was performed. SYT-SSX2 transcripts were detected in all 3 cases. These cases indicate that synovial sarcoma of the kidney should be considered in the differential diagnosis of mesenchymal kidney tumors with prominent rhabdoid features. A subset of adult rhabdoid tumors may be a rhabdoid variant of synovial sarcoma, and molecular studies to detect SYT-SSX fusion transcripts are recommended for an accurate diagnosis.
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PMID:Synovial sarcoma of the kidney with rhabdoid features: report of three cases. 1510 52

We studied whether the expression of the Neuropilin (NRP) gene was correlated with clinicopathological features in glioma. We examined the gene expression of vascular endothelial growth factor (VEGF)-A, Flt-1, KDR, NRP1 and NRP2 in 37 gliomas by real time reverse transcriptase PCR (real time RT-PCR) as well as immunohistochemical analysis. The vascular counts of each tumor were evaluated by anti-CD34 antibody. NRP1 mRNA overexpression was significantly higher in neoplastic tissue compared to normal brain tissue samples. The higher grade of glioma overexpressed the NRP1 gene significantly (p=0.0015). The glioma patients with NRP1 overexpression showed a poorer prognosis (p=0.0202) than those without such overexpression. NRP1 was observed in the glioma cells by immunohistochemical analyses. VEGF-A and VEGFR overexpression did not show any correlation with the clinicopathological features, including NRP expression. These results suggest that NRP1 overexpression, rather than VEGF-A or VEGFR, contributes to tumor progression and has clinical significance for glioma.
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PMID:Overexpression of the neuropilin 1 (NRP1) gene correlated with poor prognosis in human glioma. 1516 Sep 92

Human angiogenin is a 14-kDa secreted protein with angiogenic and ribonucleolytic activities. Angiogenin is associated with tumour development but is also present in normal biological fluids and tissues. To further address the physiological role of angiogenin, we studied its expression in situ and in vitro, using the human term placenta as a model of physiological angiogenesis. Angiogenin was immunodetected by light and transmission electron microscopy, and its cellular distribution was established by double immunolabelling with cell markers including von Willebrand factor, platelet/endothelial cell adhesion molecule-1 (PECAM-1), CD34, Tie-2, vascular endothelial cadherin (VE-cadherin), vascular endothelial growth factor receptor-2 (VEGF-R2), erythropoeitin receptor (Epo-R), alpha-smooth muscle actin, CD45, cytokeratin 7, and Ki-67. Angiogenin immunoreactivity was detected in villous and extravillous trophoblasts, the trophoblast basement membrane, the endothelial basal lamina, foetal blood vessels, foetal and maternal red blood cells, and amnionic cells. Its expression was confirmed by in situ hybridisation with a digoxygenin-labelled cDNA probe and reverse transcriptase-polymerase chain reaction amplification. Villous cytotrophoblasts, isolated and differentiated in vitro into a functional syncytiotrophoblast, expressed and secreted angiogenin. Given its known biological activities in vitro and its observed pattern of expression, these data suggest that, in human placenta, angiogenin has a role not only in angiogenesis but also in vascular and tissue homeostasis, maternal immune tolerance of the foetus, and host defences.
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PMID:Angiogenin distribution in human term placenta, and expression by cultured trophoblastic cells. 1516 1

Human fetal cord blood contains subsets of mononuclear cells with the potential to form both hematological and endothelial cells. Vascular progenitor cells, which can produce all three elements of mature blood vessels, including smooth muscle, have been identified in animals. We hypothesized that similar multipotential progenitor cells exist in humans and used the expression of alpha-smooth muscle actin (alpha-SMA) to identify such cells in fetal cord blood. Mononuclear cell preparations were isolated from human umbilical cord blood and CD34(+) and CD133(+) cells obtained by magnetic bead separation. Isolated cells were cultured on fibronectin-coated dishes with medium containing vascular endothelial growth factor, basic fibroblast growth factor, and insulin-like growth factor. mRNA was extracted, and the expression of alpha-SMA and a number of endothelial cell markers (VEGFR-2, vWF, eNOS, VE-Cadhein, PECAM-1 and Tie-2) was determined by reverse transcriptase-PCR techniques. Human umbilical vein endothelial cells (HUVECs) were used as positive controls. Freshly isolated CD34(+) and CD133(+) cells expressed all endothelial cell markers, but did not express alpha-SMA. HUVECs expressed alpha-SMA. Following 4 weeks of culture, CD34(+) isolates produced morphologically endothelial-like cells that expressed both endothelial cell markers and alpha-SMA. CD133(+) cells failed to produce morphological endothelial-like cells but expressed a range of endothelial markers. However, they did not express alpha-SMA. Following culture in an endothelial cell-promoting environment, CD34(+), but not CD133(+), isolates produced endothelial-like cells that expressed alpha-SMA. Human fetal cord blood contains a population of cells that may differentiate toward both an endothelial and a smooth muscle phenotype in culture.
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PMID:Smooth muscle alpha-actin expression in endothelial cells derived from CD34+ human cord blood cells. 1558 9

Several reports have shown that the expression of Sca-1 (Ly-6A/E), the most widely used murine hematopoietic stem cell marker, is restricted to blood vessels in several nonhematopoietic tissues. However, there is no information about which components are expressing Sca-1, and what the role of Sca-1 could be. Because we have previously shown that murine liver endothelial cells from the hepatic sinusoid (LSEC) express some HSC markers (i. e., CD34 and c-kit), we hypothesized that these cells could also express Sca-1. In this work, we show that Sca-1 is constitutively expressed in LSEC, as well as in the liver sinusoid lumen. The expression of Sca-1 in LSEC was confirmed at the mRNA and protein level by reverse transcriptase (RT)-PCR, flow cytometry, and immunofluorescence studies. The expression of Sca-1 was enhanced on the surface of LSEC by tumor necrosis factor (TNF). We examined whether Sca-1 ligation on the surface of LSEC regulates some biological response in these cells. Our results show that ligation of Sca-1 by the anti-Ly-6A/E monoclonal antibody (mAb) D7 stimulated the growth of LSEC and the production of interleukin-6 (IL-6) by these cells. To our knowledge, this is the first report that LSEC express Sca-1, which may constitute additional support to the theory of a common progenitor for the hematopoietic and endothelial cells. Our results show a novel role of Sca-1, indicating that it induces activation of LSEC to proliferate and to produce IL-6. These results suggest that Sca-1 may participate in several clinical conditions such as angiogenesis and inflammation.
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PMID:Expression of the hematopoietic stem cell antigen Sca-1 (LY-6A/E) in liver sinusoidal endothelial cells: possible function of Sca-1 in endothelial cells. 1558 10

Inhibitory member of the ASPP family (iASPP) is an evolutionarily conserved inhibitor of p53, and its expression is upregulated in human breast carcinomas expressing wild-type p53. To examine the role of iASPP in acute leukemia (AL), we analyzed iASPP mRNA expression in AL by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). PCR products were confirmed by restriction endonuclease BstX I digestion and sequencing analysis. The results showed that median levels of iASPP gene expression in cells of AL were significantly higher than those in cells from normal donors and AL patients in complete remission (CR) (P = 0.019, 0.021, respectively). There was no significant difference between acute lymphocytic leukemia (ALL) cells and acute myeloid leukemia (AML) cells (P = 0.593). The expression level of iASPP gene and its overexpression in M3 and M4EO were significantly lower than in other subtypes of AML. However, iASPP gene expression in AL cells was not associated with gender, age, initial white blood cell count or p53 type, but was associated with CD34 expression. The results of the present study suggest that iASPP gene overexpression may play an important role in the leukemogenesis and/or disease progression of AL.
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PMID:The expression of iASPP in acute leukemias. 1560 67

Local bone marrow (BM) renin-angiotensin system (RAS) is an autocrine-paracrine system affecting normal and neoplastic hematopoiesis. Angiotensin II type 1a (AT1a) receptors are present on the CD34(+) hematopoietic stem cells (HSC). Angiotensin II stimulates the proliferation and differentiation of the HSC populations through the activation of AT1 receptors on HSC. Umbilical cord blood (UCB) is a rich source of HSC. The existence of a complete local UCB RAS has not been previously investigated. In this study, local synthesis of the major RAS components, namely, angiotensin-converting enzyme (ACE), renin, and angiotensinogen, was identified by demonstrating their corresponding mRNAs using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) in human UCB. Local RAS could regulate cellular growth in a variety of tissues including the BM. Major RAS peptides can exert significant effects on primitive pluripotential HSC populations. Further studies should focus on the interactions between possible autocrine, paracrine, endocrine, and intracrine actions of the local UCB RAS and growth, engraftment, differentiation, and plasticity functions of HSC of UCB origin.
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PMID:Local umbilical cord blood renin-angiotensin system. 1564 31

This study was aimed to characterize the mitochondrial and extra-mitochondrial oxygen consuming reactions in human CD34+ hematopoietic stem cells. Cell samples were collected by apheresis following pre-conditioning by granulocyte colony-stimulating factor and isolated by anti-CD34 positive immunoselection. Polarographic analysis of the CN-sensitive endogenous cell respiration revealed a low mitochondrial oxygen consumption rate. Differential absorbance spectrometry on whole cell lysate and two-dimensional blue native-PAGE analysis of mitoplast proteins confirmed a low amount of mitochondrial respiratory chain complexes thus qualifying the hematopoietic stem cell as a poor oxidative phosphorylating cell type. Confocal microscopy imaging showed, however, that the intracellular content of mitochondria was not homogeneously distributed in the CD34+ hematopoietic stem cell sample displaying a clear inverse correlation of their density with the expression of the CD34 commitment marker. About half of the endogenous oxygen consumption was extra-mitochondrial and completely inhibitable by enzymatic scavengers of reactive oxygen species and by diphenylene iodinium. By spectral analysis, flow cytometry, reverse transcriptase-PCR, immunocytochemistry, and immunoprecipitation it was shown that the extra-mitochondrial oxygen consumption was contributed by the NOX2 and NOX4 isoforms of the O2-*. producer plasma membrane NAD(P)H oxidase with low constitutive activity. A model is proposed suggesting for the NAD(P)H oxidase a role of O2 sensor and/or ROS source serving as redox messengers in the activation of intracellular signaling pathways leading (or contributing) to mitochondriogenesis, cell survival, and differentiation in hematopoietic stem cells.
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PMID:Characterization of mitochondrial and extra-mitochondrial oxygen consuming reactions in human hematopoietic stem cells. Novel evidence of the occurrence of NAD(P)H oxidase activity. 1588 63


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