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

DNA polymerase alpha is a DNA replicating enzyme expressed in all proliferating cells. This nuclear antigen in paraformaldehyde-postfixed frozen sections of normal, benign, and malignant tissues was identified by the peroxidase-antiperoxidase technique with the use of a mouse monoclonal antibody against bovine/human DNA polymerase alpha. The nuclei of normal proliferating cells were positive. Malignant tumors (n = 95) showed a higher proportion of positive nuclei than did low-grade malignant tumors (n = 7) or benign lesions (n = 67). The number of positive nuclei in squamous cell carcinomas (n = 19) was higher than in adenocarcinomas (n = 45). Eight (18%) adenocarcinomas and all five renal cell carcinomas had less than 10% positive cells, whereas in benign tissues, such as pituitary adenomas, a thymoma, reactive lymphoid lesions, and some benign mammary nodules, more than 10% of nuclei were labeled. In addition, foci of proliferating cells were clearly recognized. DNA polymerase alpha is, therefore, an excellent marker of proliferative activity that provides an approach to analyzing tumor cell heterogeneity not only in fully developed neoplasms, but also in their precursor lesions.
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PMID:DNA polymerase alpha. An immunohistochemical marker for proliferating cells in normal and neoplastic human tissues. 169 87

To compare the time course of in vitro expression of various proliferation-associated markers including Ki-67 antigen, transferrin receptors (TfR), and DNA polymerase alpha, six human tumour cell lines of different histological origin were studied under defined conditions. Proliferation markers were demonstrated by peroxidase/anti-peroxidase staining using specific monoclonal antibodies, and their expression was compared to results obtained from [3H]-thymidine incorporation assays and cell counting. Expression of all proliferation markers began to increase during the lag phase, and occurred earlier than elevations of [3H]dT incorporation and cell numbers were recorded. Maximum expression was observed before cell growth reached plateau phase. The time courses of expression of DNA polymerase and Ki-67 were almost identical. The closest correlation of [3H]dT incorporation with time course of expression of proliferation-associated markers was observed, when intranuclear staining of DNA polymerase was analysed. TfR were expressed earlier than the polymerase and Ki-67. Since TfR were also found at remarkable levels in resting cells, they seem less proliferation-specific than Ki-67 and DNA polymerase. While in rapidly growing cell lines more than 95% of the cells expressed Ki-67, TfR, and more than 75% DNA polymerase in cell nuclei, a malignant melanoma and a pleural mesothelioma line displayed fewer than 35% of cells stained for DNA polymerase in cell nuclei during log phase. Determination of growth fractions by monoclonal antibodies may thus contribute to the prediction of chemoresistance by identifying quiescent cells that are not sensitive to S-phase-specific drugs.
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PMID:Expression of the proliferation-associated Ki-67 antigen of transferrin receptors and of DNA polymerase alpha in human tumour lines: implications for in vitro chemoresistance. 173 31

Anti-idiotypic antibodies (anti-Id) against anti-HBs were found in the sera of patients with chronic hepatitis type B. Anti-idiotypic antibodies were detected by an enzyme-linked immunosorbent assay using horseradish peroxidase conjugated mouse monoclonal anti-HBs. Ten of 72 HBsAg positive sera contained anti-Id (13.9%). The prevalence of anti-Id did not appear to correlate with HBeAg/anti-HBe system. However, HB virus specific DNA polymerase activity was significantly higher in anti-Id positive sera. In the sera obtained from the patients treated with predonisolone before, anti-Id positive rate was higher than that in the patients without a history of predonisolone therapy. These results suggest that anti-Id may be related to the immunoregulatory mechanism of HB virus replication.
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PMID:Anti-idiotypic antibodies directed against anti-HBs among the patients with chronic hepatitis B. 225

An in vivo 5'-bromodeoxyuridine (BrdUrd) labeled DNA probe was used for in situ DNA-RNA hybridization. BrdUrd was incorporated into plasmid DNA by inoculating E. coli with Luria-Bertani (LB) culture medium containing 500 mg/L of BrdUrd. After purification of the plasmid DNA, specific probes of the defined DNA fragments, which contained the cloned insert and short stretches of the vector DNA, were generated by restriction endonuclease. The enzymatic digestion pattern of the BrdUrd-labeled plasmid DNA was the same as that of the non-labeled one. BrdUrd was incorporated in 15%-20% of the total DNA, that is, about 80% of the thymidine was replaced by BrdUrd. Picogram amounts of the BrdUrd-labeled DNA probe itself and the target DNA were detectable on nitrocellulose filters in dot-blot spot and hybridization experiments using a peroxidase/diaminobenzidine combination. The BrdUrd-labeled DNA probe was efficiently hybridized with both single stranded DNA on nitrocellulose filters and cellular mRNA in in situ hybridization experiments. Through the reaction with BrdUrd in single stranded tails, hybridized probes were clearly detectable with fluorescent microscopy using a FITC-conjugated monoclonal anti-BrdUrd antibody. The in vivo labeling method did not require nick translation steps or in vitro DNA polymerase reactions. Sensitive, stable and efficient DNA probes were easily obtainable with this method.
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PMID:In situ DNA-RNA hybridization using in vivo bromodeoxyuridine-labeled DNA probe. 247 24

Some factors influencing the detection of human cytomegalovirus (HCMV) in urine were investigated employing 2 enzyme-linked immunosorbent assays (ELISAs); one utilised anti-CMV DNA polymerase while the other anti-CMV mouse monoclonals as the detecting antibodies. The use of anti-CMV DNA polymerase was found to be superior in detecting HCMV in both urine and tissue culture fluids than anti-CMV monoclonals. Furthermore, alkaline phosphatase conjugates produced much lower background than did peroxidase conjugates. In reconstruction experiments, the extremes of pH in the urine clearly had an adverse effect on the detection rate of extracellular virus. pH correction of urines to neutrality improved the detection rate considerably. On the other hand, pH correction had little effect on the detection rate of intracellular HCMV in urine, although it was improved when specimens were subjected to repeated cycles of freeze-thawing, ultrasonication, and storage at 4 degrees C. It was concluded that, in addition to the factors investigated which all appear to affect virus detection rate, there may well be additional factors that interfere with CMV detection in the urine by ELISA particularly with intracellular virus.
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PMID:Factors affecting the detection of cytomegalovirus in urine by sandwich enzyme immunoassays. 302 18

Liver biopsy specimens from 58 American patients with chronic type B hepatitis were investigated for the presence and distribution of the hepatitis B core (HBcAg) and surface (HBsAg) antigens by peroxidase-anti-peroxidase techniques. HBsAg was detected in 43 (77%) and HBcAg in 52 (90%) patients. HBcAg was present in 50 of 51 (98%) patients with hepatitis B e antigen (HBeAg) but in only two of seven (29%) of patients with antibody to HBeAg (anti-HBe). There was no correlation between severity of hepatitis or height of aminotransferase activities and the amount of HBsAg or HBcAg in hepatocytes but there was a positive correlation between amount of HBcAg and height of HBV-DNA and DNA polymerase activity in serum. Follow-up liver biopsies, taken 1 to 3 yr later, were available from 39 patients. HBcAg remained detectable in 25 of 26 patients with persistence of HBeAg but disappeared in 12 patients who had lost HBeAg. In nine patients, HBcAg was cytoplasmic as well as nuclear in distribution. Seven of these patients had an intense lobular hepatitis with marked elevations in aminotransferase activities. These findings indicate that the amount of HBcAg in liver correlates with the amount of serum hepatitis B virus as quantified by serum levels of DNA polymerase and HBV-DNA. The amount of nuclear HBcAg does not correlate with the severity of the liver disease, but the presence of cytoplasmic HBcAg usually reflects an active and severe ongoing hepatitis.
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PMID:Peroxidase-anti-peroxidase detection of hepatitis B surface and core antigen in liver biopsy specimens from patients with chronic type B hepatitis. 332 17

We have developed a simple and rapid nonradioactive method for detecting genetic variation and have applied it to the diagnosis of sickle cell anemia and beta-thalassemia. The procedure involves the selective amplification of a segment of the human beta-globin gene with oligonucleotide primers and a thermostable DNA polymerase, followed by hybridization of the amplified DNA with allele-specific oligonucleotide probes covalently labeled with horseradish peroxidase. The hybridized probes were detected with a simple colorimetric assay. We demonstrated the usefulness of this method in a retrospective analysis of two pregnancies at risk for beta-thalassemia and one at risk for sickle cell anemia, as well as in an analysis of nine DNA samples simulating three family sets.
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PMID:Diagnosis of sickle cell anemia and beta-thalassemia with enzymatically amplified DNA and nonradioactive allele-specific oligonucleotide probes. 340 66

The lymphocyte subsets in the peripheral blood and in liver biopsies from 4 patients with chronic hepatitis B obtained about 2-7 weeks before and after treatment with adenine arabinoside (Ara-A) were studied by a peroxidase-labeled antibody method using monoclonal antibodies against Leu-1, Leu-2a, Leu-3a, Leu-7 and Leu-10 antigens. In the peripheral blood, the percentage of Leu-2a+ (cytotoxic/suppressor) cells was significantly reduced and the ratio of Leu-3a+ (helper/inducer) to Leu-2a+ cells was increased after the treatment with Ara-A. In the liver biopsies, the numbers of Leu-1+ (pan T) and Leu-2a+ cells were significantly decreased after the treatment with Ara-A. As a result, the Leu-3a+/Leu-2a+ ratio was significantly elevated in the liver after the therapy. The majority of lymphocytes distributed at sites of hepatocytic necrosis were positive for Leu-2a. The reduced numbers of Leu-1+ and Leu-2a+ cells after the treatment were mainly due to the decrease of these cells infiltrating to the sites of hepatocytic necrosis. The numbers of other subsets (Leu-3a+, Leu-7+ and Leu-10+) changed without any specific tendency both in the peripheral blood and in the liver biopsies after the treatment. With respect to viral replication, most of the patients showed a decrease of serum DNA polymerase activity or demonstrable intrahepatic HBsAg and HBcAg after the treatment. These data suggest that T cell-mediated cytotoxicity against HBV-infected hepatocytes is diminished after treatment with Ara-A.
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PMID:Effects of adenine arabinoside on cellular immune responses in patients with chronic hepatitis B. 373 54

A variety of factors were found to modify the toxicity of L-dopa in HeLa cells (D37 16 microM) and in dopa-sensitive, nonpigmented human melanoma cells (MM96) (D37 5 microM) having a similar size and doubling time. Dopa toxicity was decreased by concurrent treatment with superoxide dismutase, peroxidase or catalase, by erythrocytes, or by hypoxia. Toxicity could be increased by the enzyme inhibitors L- and D-penicillamine, sodium diethyldithiocarbamate or 3-amino-1,2,4-triazole. The two cell lines had similar levels of superoxide dismutase and peroxidase; in 6 human melanoma lines, no correlation was found between dopa killing and tyrosinase activity as determined either by formation of dopa from tyrosine or by formation of melanin from dopa. Uptake of L-dopa was similar in HeLa and MM96 cells, and the toxicity of D-dopa was the same in both lines as that of the L-isomer. Dopa decomposed within 12 hr in culture medium, the rate and products being influenced by addition of the above enzymes and by the cell density. Dopa-melanin and medium containing decomposed dopa were also selectively toxic to MM96 cells. Adenovirus 5 was used in two different ways to assess the relative importance of DNA damage and inhibition of DNA synthesis by dopa. Viral replication was found to be unaffected in cells being treated with dopa but was strongly inhibited in cells treated with the DNA polymerase inhibitor cytosine arabinoside. Secondly, the virus was itself inactivated by treatment with dopa for 24 hr (D37 1.3 mM); similar dose response curves were obtained for replication of dopa-treated virus in untreated HeLa or MM96 cells. These results show that the initial events of dopa toxicity occur outside the cell and lead to the formation of a stable, toxic product (probably melanin) which does not strongly inhibit DNA polymerase activity. Melanoma hypersensitivity was not due to differences in oxygen-metabolizing enzymes, dopa uptake, or DNA repair.
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PMID:Modification of dopa toxicity in human tumour cells. 392 49

A recently modified method using peroxidase labeled antibodies for light and electron microscopic demonstration of hepatitis B virus (HBV) was applied to the evaluation of hepatitis B surface antigen (HBsAg) on the surface of liver cells in biopsy specimens from 24HBsAg chronic carriers. Membranous distribution of HBsAg was demonstrated in diffuse or scattered hepatocytes in all 4 asymptomatic carriers and in 3 of the 20 patients with HBsAg-positive chronic active hepatitis or liver cirrhosis. In these patients with membranous expression of HBsAg, hepatitis B e antigen, Dane particles and DNA polymerase were often detected in sera, and large amounts of hepatitis B core antigen appeared in the liver. These results suggest that membrane-bound HBsAg may be expressed by the HBV genome. The ultrastructural study of liver cells showing membranous expression disclosed dense deposits of reaction product indicative of HBsAg on the cell membrane and/or on assembled particles within the extracellular space. In some hepatocytes showing both diffuse cytoplasmic and membranous expression of HBsAg, HBsAg-positive membrane of cisternae open to the intercellular space was connected with the liver cell membrane. These findings supported the conjecture that HBV associated antigens are integrated into the liver cell membrane.
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PMID:Immunoelectron microscopic observation of hepatitis B surface antigen on the surface of liver cells from patients with hepatitis B virus infection. 644 86


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