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)

A non-radioactive 96-well microtitre plate reverse transcriptase (RT) assay, based on the use of covalently bound riboadenosine homopolymer in the wells and 5-bromodeoxyuridined 5'-triphosphate (BrdUTP) as dNTP, is described. The whole assay is performed in a single well, including the quantitative detection of incorporated BrdU, which is performed immunologically using alkaline phosphatase-conjugated anti-BrdU antibody and colorometric reading. The system also allows the use of variable amounts of primer. The kinetics and characteristics of the assay using BrdUTP is similar to the use of [3H]dTTP. The sensitivity of the assay can be varied either by altering the duration of RT assay time and/or by prolonging the alkaline phosphatase reaction. Thus the assay can detect < 0.02 pg of recombinant human-immunodeficiency-virus (HIV) type I RT, < 0.005 m unit of avian-myeloblastosis-virus RT or < 0.02 m unit of recombinant Moloney-murine-leukaemia-virus RT. The assay was found to be useful with various types of cell-culture material, and a comparative study of 16 HIV-infected lymphocyte cultures, using 10 microliters of supernatant medium for RT assay and 22.5 microliters for p24 antigen assay showed that the new RT assay was at least 25-fold more sensitive than the p24 antigen assay. The results also show a good correlation between the RT activities found and the p24-antigen level detected, with exception for HIV2 isolates, as they only became positive in the RT assay. The technical performance and the capacity of the test compared with other available RT kits is discussed, as well as its use for other applications.
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PMID:A sensitive assay for the quantification of reverse transcriptase activity based on the use of carrier-bound template and non-radioactive-product detection, with special reference to human-immunodeficiency-virus isolation. 863 77

Osteoblasts are derived from precursor cells present in low frequency in the stromal element of bone marrow. Because of the lack of a practical procedure to isolate osteoblast precursors from early cultures of plastic adherent cells from bone marrow, previous studies of marrow stromal cells have been made in confluent cultures of bone marrow when the osteoblast (OB) precursors are already differentiated. Also these studies utilized cultures containing mixed populations of cells including hematopoietic cells. Thus we have employed a negative immunoselection procedure to remove contaminating hematopoietic cells and to isolate nearly homogeneous populations of early human stromal cells derived from the plastic-adherent mononuclear marrow cells cultured in the presence of serum. By reverse transcriptase polymerase chain reaction (RT-PCR) analysis for mRNA, and by immunocytochemical study for protein, we studied the sequential expression in culture of multiple markers of the osteoblast phenotype--alkaline phosphatase, osteopontin, parathyroid hormone receptor, types I and III procollagen, and osteocalcin--as well as lipoprotein lipase (LPL), a marker of the adipocyte phenotype. At an early stage of culture (7-9 days), human OB precursors formed colonies of variable sizes that expressed low levels of mRNA and protein concentrations of OB markers, and their concentration increased on growth to a confluent monolayer (approximately 14 days). LPL mRNA was expressed at high levels in the colony stage, and its level decreased upon confluency, suggesting a loss of potential for commitment to the adipocyte lineage. Interestingly, treatment with dexamethasone at 10(-8) M increased the expression for some of the osteoblast markers and for the LPL gene and was required for the deposition of mineralized matrix and for the formation of adipocytes containing cytoplasmic lipid droplets in confluent cultures. Cloned single early colonies were able to coexpress the osteoblast and adipocyte markers (as assessed by RT-PCR). Thus these immunoselected marrow stromal cells have the characteristics of authentic human osteoblast precursor cells which also are capable of differentiating into adipocytes.
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PMID:Isolation and characterization of osteoblast precursor cells from human bone marrow. 885 42

We tested the sera of 67 consecutive patients for hepatitis G virus (HGV) RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). These patients (42 males and 25 females, median age 35 years, range 13-64 years) had liver disease of unknown aetiology and were without markers of hepatitis (A-E) viruses or signs of genetically determined, autoimmune, alcoholic or drug-induced liver disease. The controls in this study were 110 patients (50 females and 60 males, median age 45 years, range 9-65 years) with chronic hepatitis B virus (HBV) infection (19 patients) or hepatitis C virus (HCV) infection (91 patients). Ten of 67 (14.9%) patients with cryptogenic disease were positive for HGV RNA by at least three separate tests; HGV RNA was also detected in one of 19 (5.3%) hepatitis B surface antigen (HBsAg) carriers and in nine of 91 (16.6%) patients with antibody to HCV. These data suggest that HGV occurs as frequently in HCV-infected patients as in those with cryptogenic disease. Elevated serum gamma glutamyl transpeptidase (gamma-GT) (higher than twice the normal value) and alkaline phosphatase levels were found in eight of 10 (80%) HGV RNA positive patients and in six of 57 (10.5%) HGV RNA negative patients (P < 0.0001). Five (50%) HGV RNA positive patients had non-specific inflammatory bile duct lesions. A statistically significant difference was observed between HGV RNA positive and negative patients with chronic HBV or HCV infections (P < 0.029). Therefore, the spectrum of liver disease associated with HGV is wide, but a characteristic lesion of the bile duct leading to elevation of cholestatic enzymes might be specific for this virus.
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PMID:Hepatitis G virus RNA in the serum of patients with elevated gamma glutamyl transpeptidase and alkaline phosphatase: a specific liver disease? [corrected]. 894 81

A microtiter well-based quantitative reverse transcriptase-PCR assay for determination of BCR-ABL mRNA, which relies on coamplification of the target with an RNA internal standard (IS), was developed. The hapten digoxigenin (Dig) is incorporated during PCR. Target RNA and IS contain identical primer recognition sites and generate same-sized amplification products distinguishable by hybridization with probes specific to the molecules' central part. The hybrids are determined with an anti-Dig-alkaline phosphatase conjugate with fluorosalicylphosphate as substrate. Fluorescent complexes of fluorosalicylate-Tb(III)-EDTA are measured by time-resolved fluorometry. The ratio of fluorescence values for target and IS is linearly related to initial target RNA in the range of 1000 to 200000 molecules. Samples containing K562 total RNA amidst 1 microgram of RNA from normal cells give fluorescence ratios that are linearly related to 30-10000 K562 cells. CVs for 30, 200, and 900 K562 cells are approximately 11%.
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PMID:Quantitative RT-PCR combined with time-resolved fluorometry for determination of BCR-ABL mRNA. 896 27

The presence of types of alkaline phosphatase (ALP) other than the tissue non-specific type enzyme in rat liver and its increase by fat feeding are known. In order to examine expression of intestinal type ALP in liver, specific oligonucleotide primers corresponding to two types of mRNAs of rat intestinal ALP (RTIN-1 and -2) were designed and amplified by means of the reverse transcriptase-polymerase chain reaction (RT-PCR). It was found that RTIN-1 mRNA was expressed only in the intestine but not in the liver, while RTIN-2 mRNA was expressed both in the intestine and in the liver. By fat feeding, expression of RTIN-1 mRNA increased in the intestine and that of RTIN-2 mRNA increased both in the intestine and in the liver. Thus, it was concluded that rat liver expressed one of the intestinal type ALP (RTIN-2) which was enhanced by fat feeding.
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PMID:Expression of mRNA encoding intestinal type alkaline phosphatase in rat liver and its increase by fat-feeding. 902 13

Adolescent female mice were inoculated intraperitoneally with coxsackievirus B3 Nancy strain, sacrificed 3 and 5 days later and the livers harvested. A protocol for direct reverse transcriptase in situ PCR (RT-ISPCR) detection of enteroviral RNA in paraffin-embedded liver tissues was developed. The optimal conditions for the assay were determined. The best results were obtained when the tissue was fixed in formalin, prior to being embedded in paraffin, then cut in 5 micron thick sections, and mounted onto silanized slides. After deparaffination the slides were incubated in 1 microgram/m1 Proteinase K for 10 min and cDNA synthesis was carried out. For successful RT-ISPCR 40-50 cycles of amplification were necessary. The optimal concentrations of dNTP, primers and Taq Polymerase for RT-ISPCR were determined by serial dilution assays. Primers were selected from highly conserved sequences in the 5' non-coding region (5'NTR). To detect the viral RNA in the liver, digoxigenin-dUTP was incorporated during amplification, subsequently bound with an antidigoxigenin antibody conjugated to alkaline phosphatase (AP), followed by colorimetric detection with nitroblue tetrazolium salt (NBT) and 5-brom-4chloro-3indolyl-phosphate (BCIP). The result was a blue precipitate in the cytoplasm of hepatocytes from infected mice. Fibroblasts, endothelial cells, lymphocytes and the nuclei of hepatocytes were negative. Thus, RT-ISPCR is a specific method for the detection of enterovirus RNA in the hepatocytes of infected mice, and can be of use for the determination of EV liver disease in man.
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PMID:Direct in situ transcriptase polymerase chain reaction for the detection of Enterovirus genome in liver tissues. 912 62

Osteoblasts are established targets of estrogen action in bone. We screened 66 conditionally immortalized clonal human osteoblast cell lines for estrogen receptors (ERs) using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for ER alpha mRNA and transactivation of adenovirus-estrogen response element (ERE)-tk-luciferase by 17 beta-estradiol (17 beta-E2) for functional ER protein. One of these cell lines, termed HOB-03-CE6, was chosen for further characterization. The cells, which were conditionally immortalized with a temperature-sensitive SV40 large T antigen, proliferated at the permissive temperature (34 degrees C) but stopped dividing at the nonpermissive temperature (> or = 39 degrees C). Alkaline phosphatase activity and osteocalcin secretion were upregulated by 1 alpha, 25-dihydroxyvitamin D3 in a dose-dependent manner. The cells also expressed type I collagen and other bone matrix proteins, secreted a variety of growth factors and cytokines, formed mineralized nodules based on alizarin red-S and von Kossa histochemical staining, and responded to dexamethasone, all-trans retinoic acid, and transforming growth factor-beta 1. This cell line expressed 42-fold less ER message than MCF-7 human breast cancer cells, as determined by quantitative RT-PCR. However, adenovirus-ERE-tk-luciferase activity was upregulated three- to fivefold in these cells by 17 beta-E2 with an EC50 of 64 pM. Furthermore, this upregulation was suppressed by co-treatment with the anti-estrogen ICI-182, 780. Cytosolic extracts of these cells specifically bound [125I]-17 beta-E2 in a concentration-dependent manner with a Bmax of 2.7 fmoles/mg protein (approximately 1,200 ERs/cell) and a Kd of 0.2 nM. DNA gel-shift analysis using a [32P]-ERE demonstrated the presence of ERs in nuclear extracts of these cells. Moreover, binding of the extracts to this ERE was blocked by a monoclonal antibody to the human ER DNA-binding domain. We evaluated these cells for 14 of 20 reported endogenous responses to 17 beta-E2 in osteoblasts. Although most of these responses appeared to be unaffected by the steroid, 17 beta-E2 suppressed parathyroid hormone-induced cAMP production, as well as basal interleukin-6 mRNA expression; conversely, the steroid upregulated the steady-state expression of alkaline phosphatase message in these cells. In summary, we have identified a clonal, conditionally phenotypic, human osteoblast cell line that expresses functional ERs and exhibits endogenous responses to 17 beta-E2. This cell line will be a valuable in vitro model for exploring some of the molecular mechanisms of estrogen action in bone.
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PMID:Functional properties of a conditionally phenotypic, estrogen-responsive, human osteoblast cell line. 913 93

Monoclonal antibody 57B specifically detects MAGE-3 gene protein expression. MAGE-derived peptides are recognized by CD8+ T cells and applied in immunotherapy. We examined formalin-fixed, paraffin-embedded tissue of 61 melanoma (primary, n = 40; metastatic, n = 21) and 46 control cases (junctional, dermal, compound, Spitz, Reed, and balloon-cell nevi) by immunohistochemistry using the alkaline phosphatase anti-alkaline phosphatase method after antigen retrieval. Immunoreactivity was rated positive at 20 positive cells per tumor or more. Staining pattern was homogeneous, scattered, or focal. All control samples and internal controls were immunonegative. Staining with monoclonal antibody 57B showed a specificity of 100% with a sensitivity of 44%. Immunopositivity (overall, 44% of melanomas) increased along with tumor, node, and metastasis stage; pT1 showed 13%, pT2 22%, pT3a 29%, pT3b 45%, pT4 100%, pTxN1 60%, and pTxNxM1a 63% of samples positive. The staining pattern was homogeneous on pT1 to pT3a tumors, homogeneous or focal in pT3b and pT4a, and homogeneous, focal, or scattered in pTxN1 and pTxNxM1a. The frequency of immunopositivity relates well to data on mRNA expression using reverse transcriptase polymerase chain reaction in a subgroup analyzed by both methods. Monoclonal antibody 57B can be used to allow profiling of melanomas using routine archival tissue, when considering immunotherapeutic approaches involving MAGE-3-derived epitopes.
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PMID:MAGE-3 immunoreactivity in formalin-fixed, paraffin-embedded primary and metastatic melanoma: frequency and distribution. 940 5

Although the differentiation of mature osteoblasts has been well studied, there is still a need for a convenient way to study preosteoblast differentiation. Our laboratory has recently described a method for isolating small numbers of authentic osteoblast precursor cells from human bone marrow (Rickard et al., J Bone Miner Res 11:312-324, 1996). Here we describe the conditional immortalization of these cells by retroviral transfection with the amphotrophic vector, pZipSV40tsa58, which encodes for a temperature-sensitive mutant form of the simian virus large T-antigen. At the permissive temperature of 34 degrees C, the cell lines proliferated, but differentiation was arrested, whereas at the restrictive temperature of 39.5 degrees C, proliferation was decreased and differentiation was induced. As assessed by semiquantitative reverse transcriptase PCR after 4 days of culture at 39.5 degrees C, the six cell lines expressed similar mRNA levels both constitutively and in response to dexamethasone (Dex) and 1alpha,25-dihydroxyvitamin D3 (1,25(OH2)D3) for osteoblast (alkaline phosphatase [ALP], type I collagen [Col I], osteocalcin [OC], and parathyroid hormone receptor [PTH-R] and adipocyte (lipoprotein lipase [LPL]) genes. In the presence of 10(-8) M Dex, gene expression for ALP, PTH-R, and LPL increased, but that for OC decreased. Stimulation with 10(-8) M 1,25(OH2)D3 increased gene expression for ALP, OC, and Col I. Changes in protein production for ALP, OC, and type I procollagen in response to Dex and 1,25(OH2)D3 were similar to changes in mRNA levels. When cultured at 39.5 degrees C with ascorbate and beta1-glycerolphosphate for 21 days, mineralization of matrix occurred, whereas culture with Dex plus 1,25(OH2)D3, or rabbit serum led to enhanced formation of cytoplasmic lipid droplets within 6 days. Thus, these cell lines are capable of bipotential differentiation and should serve as an excellent tool to study the molecular mechanisms that regulate and select for osteoblast and adipocyte differentiation in humans.
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PMID:Development and characterization of conditionally immortalized osteoblast precursor cell lines from human bone marrow stroma. 949 13

A protocol for the in situ polymerase chain reaction (IS-PCR) detection of viral nucleic acid in the heart tissue of four-to-five-week-old CD1 mice infected with coxsackievirus B3 (CBV3) Nancy strain is described. To compare the effects of formalin concentration on the IS-PCR process, two different concentrations (10 and 37%) were employed. Using 37% formalin, 25 PCR cycles were sufficient and a permeabilization step could be omitted. However, postfixation of tissues with 4% paraformaldehyde and 100% ethanol after the deparaffinization, reverse transcriptase and amplification steps was required in order to minimize artefacts. When the tissues were fixed in 10% formalin, postfixation with 4% paraformaldehyde was not required, but a permeabilization step had to be employed and 40 cycles of PCR amplification were needed. To detect the PCR product in the 10% formalin-fixed samples, incubation with 0.3 U/ml of an anti-digoxigenin antibody conjugated to alkaline phosphatase was performed for 90 min. When 37% formalin-fixed samples were used, the concentration of the antibody conjugate had to be increased to 3 U/ml and the exposure time was decreased to 30 min. Enterovirus (EV) nucleic acid was detected in the cytoplasm of myocytes. Thus, IS-PCR was successful in localizing EV nucleic acid in the cytoplasm of myocytes in mice infected with a cardiotropic strain of CBV3. Using this technique, 10% formalin-fixed tissues gave better results than 37% formalin-fixed tissues.
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PMID:Comparison of procedures for the detection of enteroviruses in murine heart samples by in situ polymerase chain reaction. 949 12


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