Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In ongoing studies, we have tested resected lung cancers from 41 men and 49 women; of those with primary lung cancer, 46 patients are free of disease and 35 have died of cancer or have persistent disease. Measurements and studies were as follows: total cellular deoxyribonucleic acid content by image analysis (n = 77); total genomic deoxyribonucleic acid methylation state and banding patterns from probed Southern blots (n = 36); radioimmunoassay for motilin, bombesin, gastrin, vasoactive intestinal peptide, and cholecystokinin (n = 18); and cytogenetic analysis (n = 39). All lung cancers were hyperploid. Adenocarcinomas and epidermoid carcinomas were generally hexaploid to nearly septaploid; comparisons by stage and histologic features suggested potential prognostic correlations. There was general hypomethylation of deoxyribonucleic acid (p less than 0.001). Deoxyribonucleic acid digests from restriction endonuclease Hpa II, when probed with deoxyribonucleic acid homologous to KPN, showed banding patterns that separated histologically indistinguishable primary adenocarcinomas and metastatic adenocarcinomas from one another. Cancers studied with radioimmunoassay were all negative for polypeptide hormones. Five cancers grew adequately in vitro to permit study of 190 detailed karyotypes (20 to 50 per tumor). Chromosome modal numbers ranged from 49 to 109. There were from 4 to 20 clearly abnormal marker chromosomes per tumor; abnormality derived from chromosome 1 was prevalent. Ten of 19 tumors xenotransplanted to nude mice were carried through two to five transplant generations without a change in histologic patterns.
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PMID:Biochemical and cytogenetic studies of human lung cancers. 319 97

The plasmid contents of seven exfoliative toxin-producing strains of phage group 2 Staphylococcus aureus were analyzed by agarose gel electrophoresis and deoxyribonucleic acid-deoxyribonucleic acid hybridization. All strains were found to contain a large plasmid with a molecular weight of 27 X 10(6) except for strain RW1005. A comparison of the restriction endonuclease cleavage products by agarose gel electrophoresis showed that the number and size distribution of the fragments of all these Tox plasmids were similar, except for pRW002, which appeared to contain two deletions. Deoxyribonucleic acid-deoxyribonucleic acid hybridization studies confirmed that these plasmids were related to a plasmid which carried the genes for exfoliative toxin B and bacteriocin R1 biosynthesis and that they shared some sequence homology with the penicillinase plasmid pI258 isolated from a phage group 3 S. aureus.
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PMID:Exfoliative toxin plasmids of bacteriophage group 2 Staphylococcus aureus: sequence homology. 625 89

Deoxyribonucleic acids (DNAs) from wild-type and mutant strains of beta-converting and gamma-nonconverting corynebacteriophages were isolated and physically characterized. The data obtained from DNA heteroduplexes, restriction enzyme banding profiles, and restriction maps reinforce the conclusion that beta and gamma phages are very closely related. The major physical differences seen in the DNA heteroduplexes are a small substitution bubble and one or two insertions which are present on the gamma phage genome. The insertions account for the differences in the genome sizes of beta and gamma phages, and with the substitution they are responsible for most of the differences in the restriction endonuclease profiles and maps of the corynebactriophage genomes, two special sites and the DNA fragments carrying them were identified. These were the cohesive (cos) sites and the specific attachment (attP) site of the vegetative phage genome. The behavior of these sites indicated that the transition of phage DNA from the vegetative to the prophage state involves the circularization of vegetative DNA through the cos sites and its integration into the bacterial chromosome via the attP site. The mechanism of corynebacteriophage integration was similar to that employed by Escherichia coli phage gamma. From the data assembled the physical and genetic maps of beta and gamma phage were oriented with respect to one another. The extensive similarity in their maps provides additional confirmation of a close evolutionary relationship.
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PMID:Physical mapping of beta-converting and gamma-nonconverting corynebacteriophage genomes. 627 59

Using the promotor-cloning vehicle described by An and Friesen (J. Bacteriol. 140:400-410, 1979), Escherichia coli chromosomal deoxyribonucleic acid fragments derived from the lambda drifd18 transducing phage were cloned in one of several unique restriction endonuclease sites adjacent to tetracycline(tet) genes that lack their own promotor. One of these plasmids has been used to isolate nine variants having mutations that lie in a putative internal promoter which is located between rplL and rpoB. Deoxyribonucleic acid sequence analysis revealed that, in all nine mutants, a single base change, C to T, in the ribonucleic acid polymerase recognition site led to a large increase in promoter activity. Analysis of a variety of plasmids in which tet is fused to various promoters yielded the following results: (i) rplK and rplA, genes for ribosomal protein L11 and L1, respectively, were cotranscribed from a common promoter located upstream from rplK; (ii) there was a strong promoter in the region between the rplKA operon and rplJ, the gene for ribosomal protein L10; (iii) an attenuator region was located between rplL, the gene for ribosomal protein L12, and rpoB, the gene for ribonucleic acid polymerase subunit beta; (iv) transcription terminated immediately after rpoC, the gene for ribonucleic acid polymerase subunit beta'; (v) a gene coding for unknown protein U, which is located between tufB and the rplKA operon, had its own promoter; (vi) the tufB gene was separated from all of the genes described above and had its own promoter.
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PMID:Characterization of promoter-cloning plasmids: analysis of operon structure in the rif region of Escherichia coli and isolation of an enhanced internal promoter mutant. 700 14

Calphostin C acts at the regulatory domain as a highly selective inhibitor of protein kinase C (PKC), and staurosporine acts at the catalytic domain as a nonspecific PKC inhibitor. The authors investigated the capacity of calphostin C and staurosporine to promote apoptotic fragmentation of DNA in four human glioma cell lines. The exposure of glioma cell lines to 100 nM calphostin C for 2 to 8 hours induced a decrease in particulate PKC activities and exposure for 16 to 24 hours produced a concentration-dependent increase in internucleosomal DNA cleavage on agarose gel electrophoresis. In addition, the human glioma cells showed the classic morphological features of apoptosis: cell shrinkage, nuclear condensation, and the formation of apoptotic bodies. A 24-hour exposure to staurosporine failed to induce internucleosomal DNA fragmentation at concentrations generally used to achieve maximum inhibition of enzyme activity (50 nM) but promoted fragmentation at considerably higher concentration (more than 200 nM). Deoxyribonucleic acid fragments obtained from cells exposed to 100 nM calphostin C for 16 to 24 hours possessed predominantly 5'-phosphate termini, consistent with the action of a Ca++/Mg(++)-dependent endonuclease. Northern and Western blot analyses revealed that the exposure to 100 nM calphostin C for 4 hours failed to alter bcl-2 transcript and protein, but exposure for more than 8 hours decreased the amount of bcl-2 transcript and protein. Together, these observations suggest that calphostin C is capable of inducing apoptotic DNA fragmentation and cell death in a highly concentration dependent manner in human glioma cells and that the apoptosis is closely associated with the decrease in transcription and translation of bcl-2.
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PMID:Apoptosis of human glioma cells in response to calphostin C, a specific protein kinase C inhibitor. 749 Jun 14

Deoxyribonucleic acid of cells undergoing apoptosis is cleaved by a calcium-dependent endonuclease into oligonucleosomal-sized fragments. These fragments can be labeled using the enzyme terminal deoxynucleotidyl transferase so that the cells can be visualized immunohistochemically. Few investigators have evaluated this method in disease processes of the human central nervous system. The Tdt-mediated dUTP-biotin nick end labeling (TUNEL) technique has been investigated in preliminary studies of a variety of pathologic conditions of the human brain (e.g., gliomas, traumatic brain injury, Parkinson's disease, Parkinson's-Alzheimer's complex, multisystem atrophy, striatonigral degeneration). We focus, however, on Huntington's disease (HD) because of the availability of well-characterized pathological stages for study, and also because of the neurodegenerative diseases studied to date, only Huntington's disease revealed significant and consistent labeling with this method. This implies a possibly unique nature to the mechanism of cell death in Huntington's disease compared to the other neurodegenerative diseases studied. TUNEL+ neurons were found in Grade 1-4 HD neostriatum, while labeled astrocytes were found predominantly in the Grade 1 and 2 cases studied to date. TUNEL+ cells were also found in glioblastoma multiforme and traumatic brain injury. We conclude that while there appear to be several limitations associated with this technique, it may be useful for identifying both apoptosis and necrosis in certain neuropathological conditions.
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PMID:DNA end labeling (TUNEL) in Huntington's disease and other neuropathological conditions. 764 31

The virulence of the oocysts of 7 Czech Toxoplasma gondii isolates was tested. The oocysts were obtained by experimental infection of cats with the tissue cysts of T. gondii isolates from dogs, cats, and rabbits. The cats shed the oocysts in feces, with prepatent periods of 3-5 days postinfection (PI); the patent period was 7-18 days. The number of oocysts shed varied between 0.94 million and 47 million, with 0.66 million-39 million oocysts found in the daily samples of excrement. The cats ceased oocyst production at 11-22 days PI. Sporulated oocysts were used to prepare infective doses of 1 to 10(5) oocysts for oral infection of 10 mice. Deoxyribonucleic acid isolated from 4 T. gondii isolates was used in polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for amplification of the ROP1 gene and restriction of the product of amplification by restriction endonuclease DdeI. On the basis of their biological characteristics, all 7 isolates belonged to the group of "avirulent" strains. In the PCR-RFLP tests, 2 isolates, K9 and K19, showed an "avirulent" strain pattern.
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PMID:Low virulence of oocysts of Czech Toxoplasma gondii isolates on the basis of biological and genetic characteristics. 1453 90

Deoxyribonucleic acid (DNA) topoisomerases are essential for removing the supercoiling that normally builds up ahead of replication forks. The camptothecin (CPT) Top1 (topoisomerase I) inhibitors exert their anticancer activity by reversibly trapping Top1-DNA cleavage complexes (Top1cc's) and inducing replication-associated DNA double-strand breaks (DSBs). In this paper, we propose a new mechanism by which cells avoid Top1-induced replication-dependent DNA damage. We show that the structure-specific endonuclease Mus81-Eme1 is responsible for generating DSBs in response to Top1 inhibition and for allowing cell survival. We provide evidence that Mus81 cleaves replication forks rather than excises Top1cc's. DNA combing demonstrated that Mus81 also allows efficient replication fork progression after CPT treatment. We propose that Mus81 cleaves stalled replication forks, which allows dissipation of the excessive supercoiling resulting from Top1 inhibition, spontaneous reversal of Top1cc, and replication fork progression.
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PMID:Mus81-mediated DNA cleavage resolves replication forks stalled by topoisomerase I-DNA complexes. 2212 61


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