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)

The peptide guanylin, recently isolated from the intestine, and localized to cells of the gut mucosa, is involved in electrolyte/water transport in the intestinal epithelium by means of a paracrine mode of regulation. Since high amounts of this peptide are present also in the systemic circulation, we investigated the adrenal gland as a potential endocrine source of guanylin. Using a reverse transcriptase-polymerase chain reaction and hybridization with an internal oligonucleotide designed for rat guanylin, 514-bp signals were obtained in intestinal tissue and adrenal gland. Successive analyses of extracts from intestine and adrenal gland by HPLC, western blotting, and radioimmunoassay revealed the presence of the same high-molecular mass (about 12.4 kDa) guanylin that corresponds to the mass of the guanylin prohormone. About 60 fmol/ml of circulating immunoreactive guanylin was determined in plasma. Localization studies with antisera directed against different epitopes of guanylin revealed that, in the adrenal gland, guanylin immunoreactivity is restricted to the medulla, where it is mainly confined to norepinephrine chromogranin A-containing cells. On the ultrastructural level, guanylin immunoreactivity was exclusively located to secretory granules of chromaffin cells. The present data indicate that, in addition to entero-endocrine cells, the adrenal medulla represents a further source of guanylin. Thus, an endocrine mode of function of guanylin may accrue to its hitherto evidenced paracrine action in fluid transport in the intestinal epithelium. Furthermore guanylin may be considered as a neurohormonal peptide.
...
PMID:Localization, expression, and characterization of guanylin in the rat adrenal medulla. 891 64

Using both tumor specimen and cultured tumor cells, we have studied the differentiation of a pineocytoma by light and electron microscopy (EM) and immunohistochemical demonstration of glial, neuronal and neuroendocrine markers. Only interstitial cells were labeled with anti-glial fibrillary acidic protein and anti-S100 protein antibodies. Synaptophysin, neurofilaments and tau labeling was found in cells forming the pineocytomatous rosettes. Some cells also bound the anti-tryptophan hydroxylase antibody (TPOH), but no staining was seen after application of anti-chromogranin A or S-antigen antibodies. EM provided evidence for neurosensory differentiation demonstrating the presence of vesicle-crowned rodlets, cilia (9+0) and fibrous filaments. In culture, tumor cells proliferated slowly and showed positive immunolabeling for vimentin and TPOH. Expression of mRNA coding for TPOH, serotonin N-acetyltransferase, hydroxyindole-O-methyl-transferase and c-myc was found in the tumor using reverse transcriptase-polymerase chain reaction. These results demonstrate neuronal differentiation of this pineocytoma and suggest that the neoplastic pineal cells are capable of synthesizing serotonin and melatonin.
...
PMID:Immunohistochemical, ultrastructural, biochemical and in vitro studies of a pineocytoma. 960 Jun

Ewing's sarcomas (ESs), primitive neuroectodermal tumors (PNETs), and neuroblastomas (NBs) are closely related neoplasms supposedly derived from the neural crest and belonging to the family of the small blue round cell tumors of infancy and childhood. We investigated the expression of the neuroendocrine and neuroectodermal markers chromogranin A (CgA) and secretogranin II (SgII) in ESs, PNETs, and NBs, both in primitive tumors (five, nine, and four cases, respectively) and in established cell lines (three ES and two PNET cell lines). Different technical approaches, namely immunohistochemistry, Northern blot analysis, and reverse transcriptase-polymerase chain reaction (RT-PCR) were used in parallel. Chromogranin A and secretogranin II production was constantly detectable in NBs by all procedures. CgA mRNA was detectable in most ESs and PNETs only by RT-PCR, whereas SgII mRNA was detectable in some ESs and PNETs by Northern blot analysis and in all tumors by RT-PCR. CgA and SgII proteins were never detectable by immunohistochemistry in ESs and PNETs. We conclude that neuroendocrine differentiation is shared by all three tumor entities, being more overt in NBs and rudimentary in ESs and PNETs; traces of chromogranin mRNA are detectable only by a highly sensitive RT-PCR procedure.
...
PMID:Neuroendocrine differentiation in Ewing's sarcomas and primitive neuroectodermal tumors revealed by reverse transcriptase-polymerase chain reaction of chromogranin mRNA. 964 33

Evidence for the existence of neuroendocrine (NE) differentiation in non-small cell lung carcinomas (NSCLCs) is at present based on histochemical, ultrastructural, and immunohistochemical data. The aim of this study was to investigate the extent of NE differentiation in NSCLCs as revealed by mRNA analysis. Different techniques including immunohistochemistry (IHC), northern blot analysis (NBA), and reverse transcriptase-polymerase chain reaction (RT-PCR) were employed in parallel to reveal the panendocrine marker chromogranin A (CgA). The data were related to pathological, immunocytochemical (PGP 9.5, synaptophysin, Leu-7 and neuron-specific enolase), and prognostic indicators. Forty surgically resected cases of NSCLC (24 squamous cell carcinomas, 12 ordinary type adenocarcinomas, 3 bronchiolo-alveolar carcinomas, and 1 anaplastic large cell carcinoma), in which fresh frozen material was available for mRNA analysis, were collected. CgA immunoreactivity was present in five cases (12.5 per cent), generally confined to a minority of the neoplastic cell population. By RT-PCR, CgA mRNA was found in 20 cases (50 per cent), including the five tumours positive by IHC. A statistically significant correlation was found between the two techniques. By NBA, no CgA mRNA expression was detected. Leu-7 immunoreactivity was present in 15 per cent of cases, NSE in 52.5 per cent, synaptophysin in 10 per cent, and PGP 9.5 in 82.5 per cent. In NSCLC, no correlations were found between CgA production, as detected by IHC or RT-PCR methods, and the histological type, stage, grade and proliferative activity of tumours, or the disease-free interval. It is concluded that CgA gene expression can be revealed in NSCLC at both mRNA and protein levels and that RT-PCR is a valuable tool for identifying NE differentiated NSCLCs. Our data suggest that NE differentiation does not represent an independent prognostic factor in surgically resected NSCLCs.
...
PMID:Chromogranin A gene expression in non-small cell lung carcinomas. 992 30

We describe a rare case of a primary primitive neuroectodermal tumor (PNET) in the lung of a 17-year-old girl. Grossly, the tumor, located in the right lower lobe, was relatively well-circumscribed and whitish to yellowish in color with scattered hemorrhagic necrosis. Microscopically, the tumor was composed of ovoid to polygonal cells with a high nuclear to cytoplasmic ratio and relatively scant cytoplasm, arranged in solid sheets with intervening fine fibrovascular stroma. Immunohistochemically, the tumor was positive for the MIC2 gene product, whereas AE1/AE3, CAM5.2, and a variety of neuroendocrine markers such as chromogranin A, synaptophysin, and ProGRP, were negative. Three months after the lobectomy, recurrent tumors were noted in the mediastinum and right thoracic wall, and she died despite combined chemotherapy and radiation therapy. In this case cytogenetic analysis showed a hypertriploid karyotype with multiple numerical and structural chromosomal aberrations, but failed to disclose distinct evidence of translocation between chromosome 11 and 22. However, the reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated EWS/FLI-1 fusion transcripts, confirming the histopathologic diagnosis of PNET. This case indicates that the primary pulmonary PNET is a highly aggressive neoplasm occurring at a young age, and should prompt combined systemic chemotherapy, even though it is organ-confined.
...
PMID:Primary pulmonary primitive neuroectodermal tumor (PNET). A case report. 1126 15

Three (propositus) cases of basal cell carcinoma (BCC) showing endocrine differentiation at the immunohistochemical level were studied using reverse transcriptase-polymerase chain reaction (RT-PCR) to determine the presence of mRNA of chromogranin A. Moreover, 20 (consecutive) cases of BCC were studied with immunohistochemistry alone using chromogranin A, synaptophysin, S100 protein, cytokeratin 20, and neuron-specific enolase antibodies (NSE). The three propositus cases of BCC showed positive results when RT-PCR for mRNA of chromogranin A was performed. Eleven out of 20 consecutive cases of BCC were focally positive for chromogranin A antibody. These results confirm the presence of endocrine differentiation in BCC, demonstrated both with immunohistochemistry and with RT-PCR.
...
PMID:[Endocrine differentiation in basocellular carcinoma]. 1143 14

We report a case of a human gastric composite tumor occurring seven years after a partial gastrectomy for a low grade B cell MALT lymphoma. Histological examination of the tumor revealed two intimately intermingled components: 1. A moderately to poorly differentiated tubulo-acinar adenocarcinoma with signet-ring cells; and 2. Isolated or clustered small neuroendocrine cells without atypia expressing chromogranin A, somatostatin and/or glucagon, serotonin (5-HT) and, the 5-HT2B receptors. In addition to immunohistochemical detection, the presence of 5-HT2B receptors was shown pharmacologically through [125I]-DOI binding. Since 5-HT2B receptors have been demonstrated to have autocrine functions and, mitogenic and transforming properties, these results suggest a role of 5-HT in neuroendocrine malignant transformation. On the other hand, the expression of somatostatin and the detection by reverse transcriptase polymerase chain reaction (RT-PCR) of somatostatin receptor subtypes 2, 3, and 5, which have been shown to be involved in tumor regression, might account for the long evolution of this case (> 5 yr). This case illustrates the importance of local humoral modulation in tumor growth. Moreover, ultrastructural results favor a unique origin of the tumor cells from one amphicrine cell type.
...
PMID:Histological, immunohistochemical, ultrastructural and biochemical study of human gastric composite tumor: expression of the serotonin-2B receptor by the neuroendocrine component. 1147 72

High grade lung neuroendocrine carcinomas, like small and large cell neuroendocrine carcinomas, pose therapeutic problems. Most initially respond to chemotherapeutic agents, but early relapses are frequent and are resistant to the presently available treatments. Our study reports for the first time the development and evaluation of a test for detecting the presence of circulating tumour cells by measuring chromogranin A gene transcripts with reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting. The test is specific and sensitive (detection of 10 cancer cells/ml blood), and only minimally invasive. Positivity is statistically correlated to high grade neuroendocrine carcinomas and to a poor prognosis with a 3-fold higher lethal risk. The test now needs to be assessed for its usefulness as a tool in the initial staging procedures and follow-up by comparison with the recent immunoradiometric assay (RIA) for detection of chromogranin A in the serum.
...
PMID:Detection of circulating cells expressing chromogranin A gene transcripts in patients with lung neuroendocrine carcinoma. 1244 Dec 70

The incidence of prostate cancer is remarkably increased in the last decade. This dramatic epidemiological change can be primarily attributed to the widespread use of prostate specific antigen (PSA) as a diagnostic tool. Nowadays most of the prostate cancers are detected at an early stage and the age of the patients is decreased. This has led to a significantly increase in the number of prostate cancer patients treated by radical prostatectomy. Serum determination of PSA is the standard method to monitor the disease after radical surgery, while other tests can be required only when PSA is detectable. After radical prostatectomy the mean half-life of PSA is 1.5 days and it must become undetectable to consider a patient free of disease. A value greater than 0.4 ng/ml, with an increase in two determination, indicates a recurrence of the disease. PSA is an extremely sensitive marker. In fact, in patients who underwent radical prostatectomy, the presence of detectable serum PSA levels allows to detect tumor recurrence even before any other diagnostic investigation (radiological or scintigraphical) becomes able to document it ("serological" disease). Unfortunately, increasing serum PSA levels do not reveal whether a patient is affected by local relapse or by metastases, with obvious repercussion for the therapeutic choice. Clinical examination of the patient, together with random and echoguided biopsies of the vesico-urethral anastomosis, do not reveal all cases of local recurrence. Ongoing study are evaluating other diagnostic tools in the monitoring patients after radical prostatectomy, such as the serum chromogranin A, the reverse transcriptase-polymerase chain reaction for PSA and prostate specific membrane antigen (PSMA), the Positron Emission Tomography and the immunoscintigraphy with radiolabeled monoclonal antibody directed toward the PSMA.
...
PMID:[Clinical surveillance after surgery for prostate cancer]. 1267 77

Somatostatin is a potent antiproliferative signal in both tumoral and normal mammalian cells, and altered somatostatin receptor (sst) expression is associated with carcinogenesis in human tissues. In this study, two normal and three tumoral human pineal glands were analyzed using the reverse transcriptase-polymerase chain reaction (RT-PCR) for the presence of mRNA coding for the five different somatostatin receptors (sst1-sst5). Pineal parenchymal tumor (PPT) differentiation was confirmed by immunohistochemical detection of neuroendocrine markers (synaptophysin, neurofilaments, and chromogranin A). The presence of mRNA coding for c-myc, a proto-oncogene, and for tryptophan hydroxylase (TPOH), serotonin N-acetyltransferase (NAT), and hydroxyindole-O-methyltransferase (HIOMT), enzymes of the melatonin pathway, was also analyzed by RT-PCR. Only the tumoral tissues contained c-myc mRNA. All five tissues contained TPOH, NAT, and HIOMT mRNA, the levels of HIOMT mRNA being lower in PPT than in the normal pineal gland, suggesting that PPT retain the ability to synthesize melatonin. All tissues contained sst1, sst2, and sst3 transcripts, but not sst4, while small amounts of sst5 mRNA were only found in normal pineal glands. Real-time PCR, performed only with the most abundant subtpe sst2, evidenced an about sixfold higher level in in normal pineal glands. These results demonstrate the presence of somatostatin receptors in the human pineal gland, as described in other species, and point to a differential expression of the sst2 and sst5 subtypes associated with carcinogenesis.
...
PMID:Differential somatostatin receptor subtype expression in human normal pineal gland and pineal parenchymal tumors. 1270 86


1 2 Next >>

---