Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Merkel cell carcinoma is an uncommon aggressive primary cutaneous neuroendocrine carcinoma. Histologically, the differential diagnosis includes the 'small round cell' tumor group, particularly metastatic small cell carcinoma and blastic hematological malignancies involving skin/soft tissues. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase, which is a sensitive and specific antibody for acute lymphoblastic lymphoma with a small proportion of acute myeloid leukemia showing positivity. This study investigates the expression of TdT in 20 cases with initial diagnosis of Merkel cell carcinoma. Archival blocks and slides were retrieved and reviewed and clinical information obtained from patient charts. Immunohistochemistry was performed and graded as: 0, no staining; 1+, less than 50% staining in the cells; 2+, 50% or more staining in the cells. After review, 15 cases were confirmed as Merkel cell carcinoma. Immunohistochemical positivity was as follows: 8/15 cases were positive for TdT with strong nuclear staining, morphologically resembling 'blasts', AE1AE3, CAM5.2 (15/15) (both membrane and paranuclear dot positivity), CD56 and BCL-2 (15/15), Synaptophysin (13/15), Chromogranin A (11/15), NSE (15/15), CK20 (14/15), CK7 (3/15), both CK7 and CK20 (3/15), CD117 (8/15), CD99 (2/15), CD10 (1/15). One case was negative for CK7/CK20. All 15 cases were negative for thyroid transcription factor-1, LCA, CD20, CD3 and CD34. Expanded immunohistochemical panel with positive staining for epithelial/neuroendocrine markers, CK20, negative staining for hematolymphoid markers and awareness of TdT expression and other markers that show overlap with blastic hematological malignancies avoids misinterpretation in the diagnosis of Merkel cell carcinoma. This aids in further diagnosis of Merkel cell carcinoma, avoiding the potential diagnostic pitfall with other small round cell tumors and hematological malignancies primary or metastatic to the skin.
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PMID:TdT expression in Merkel cell carcinoma: potential diagnostic pitfall with blastic hematological malignancies and expanded immunohistochemical analysis. 1788 74

Merkel cell carcinoma (MCC) is a high-grade neuroendocrine carcinoma of skin characterized by cells with a "blastic" appearance, scant cytoplasm, and fine, evenly distributed chromatin. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase present in thymic T cells, lymphoblastic lymphoma/leukemia, and some cases of acute myeloid leukemia. After observing TdT immunoreactivity in a case of MCC, we analyzed 26 tumors by immunohistochemical analysis to determine their spectrum of reactivity with TdT and identified TdT in 19 (73%) of 26 MCCs. Staining intensity was variable but was often moderate to strong and present in a significant percentage of cells. Because MCC has cytomorphologic features similar to those of lymphoblastic lymphoma and may manifest as metastatic disease, reactivity with TdT in MCC could represent a diagnostic pitfall in the differential diagnosis with lymphoblastic lymphoma, particularly because the latter may lack CD45 and/or CD20, yet both neoplasms may express PAX-5, a B-cell-associated marker.
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PMID:Reactivity with TdT in Merkel cell carcinoma: a potential diagnostic pitfall. 1848 5

Polyomaviruses are a growing family of small DNA viruses with a narrow tropism for both the host species and the cell type in which they productively replicate. Species host range may be constrained by requirements for precise molecular interactions between the viral T antigen, host replication proteins, including DNA polymerase, and the viral origin of replication, which are required for viral DNA replication. Cell type specificity involves, at least in part, transcription factors that are necessary for viral gene expression and restricted in their tissue distribution. In the case of the human polyomaviruses, BK virus (BKV) replication occurs in the tubular epithelial cells of the kidney, causing nephropathy in kidney allograft recipients, while JC virus (JCV) replication occurs in the glial cells of the central nervous system, where it causes progressive multifocal leukoencephalopathy. Three new human polyomaviruses have recently been discovered: MCV was found in Merkel cell carcinoma samples, while Karolinska Institute Virus and Washington University Virus were isolated from the respiratory tract. We discuss control mechanisms for gene expression in primate polyomaviruses, including simian vacuolating virus 40, BKV, and JCV. These mechanisms include not only modulation of promoter activities by transcription factor binding but also enhancer rearrangements, restriction of DNA methylation, alternate early mRNA splicing, cis-acting elements in the late mRNA leader sequence, and the production of viral microRNA.
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PMID:Regulation of gene expression in primate polyomaviruses. 1964 Sep 99

Polymerase chain reaction (PCR) is hailed as one of the monumental scientific techniques of the twentieth century, and has become a common and often indispensable technique in many areas. However, researchers still frequently find some DNA templates very hard to amplify with PCR, although many kinds of endeavors were introduced to optimize the amplification. In fact, during the past decades, the experimental procedure of PCR was always the focus of attention, while the analysis of a DNA template, the PCR experimental subject itself, was almost neglected. Up to now, nobody can certainly identify whether a fragment of DNA can be simply amplified using conventional Taq DNA polymerase-based PCR protocol. Characterizing a DNA template and then developing a reliable and efficient method to predict the success of PCR reactions is thus urgently needed. In this study, by means of the Markov maximal order model, we construct a 48-D feature vector to represent a DNA template. Support vector machine (SVM) is then employed to help evaluate PCR result. To examine the anticipated success rates of our predictor, jackknife cross-validation test is adopted. The overall accuracy of our approach arrives at 93.12%, with the sensitivity, specificity, and MCC of 94.68%, 91.58%, and 0.863%, respectively.
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PMID:Prediction of success for polymerase chain reactions using the Markov maximal order model and support vector machine. 2563 91