Search results for "Pyrimidine"

Dermatofibrosarcoma protuberans: a comprehensive review and update on diagnosis and management

2013

Dermatofibrosarcoma protuberans (DFSP) is a rare superficial tumor characterized by high rates of local recurrence and low risk of metastasis. DFSP occurs most commonly on the trunk and proximal extremities, affects all races, and often develops between the second and fifth decade of life. The tumor grows slowly, typically over years. Histologically, several variants of DFSP have been described and should be well characterized to avoid misdiagnosis with other tumors. These include pigmented (Bednar tumor), myxoid, myoid, granular cell, sclerotic, atrophic DFSP, giant cell fibroblastoma, and DFSP with fibrosarcomatous areas. Of all these variants, only the DFSP with fibrosarcomatous areas is…

Leflunomide, a reversible inhibitor of pyrimidine biosynthesis?

1995

�ber die Wirkung von Apurins�ure und Apyrimidins�ure auf die enzymatische Desoxyribonukleins�ure-(DNA-) Synthese in vitro

1970

The effect of chemically modified deoxyribonucleic acid (DNA) on enzymatic DNA-synthesis in vitro has been investigated with analogues of DNA prepared without either purine bases (apurinic acid, APA) or pyrimidine bases (apyrimidinic acid, APyA). DNA-synthesis in vitro was studied with the deoxynucleotide polymerizing enzymes purified from calf thymus (replicative and terminal deoxynucleotidyltransferase respectively).

Hemmung von DNA-Synthese und Zellvermehrung durch Apurins�ure und Apyrimidins�ure

1968

Apurinic acid (APA) and apyrimidinic acid (APyA) prepared from deoxyribonucleic acid (DNA) by removing either purine or pyrimidine bases have been reported to inhibit enzymatic DNA-synthesis in vitro (Heicke, 1970). The present paper deals with in vivo effects of APA and APyA on mammalian cells in tissue culture.

Preparation and Structure of Bicycloalkane-Condensed Aryldiaziridines Accompanied by Pyrimidines

2007

Di-exo- and di-endo-2-aminonorbomane/enemethanamines 1-3, di-exo-oxanorbomene derivative 4 and cis-cyclohexane and trans-4-cyclohexene analogues 5, 6 were reacted with p-chlorobenzaldehyde in the presence of N-bromosuccinimide in dichloromethane. Via the reactions of 1-6, condensed diaziridines 7-12 accompanied by pyrimidine derivatives 13-16 were prepared after isolation with column chromatography. The mechanisms proposed for alternative transformations were supported by DFT calculations. The structures of the new compounds were proved by IR and NMR spectroscopy and, for 7, 9 and 12, also by means of X-ray crystallography.

Photochemical and photobiological studies with acridine and phenanthridine hydroperoxides in cell-free DNA.

1997

The acridine and phenanthridine hydroperoxides 3 and 7 were synthesized as photochemical hydroxyl radical sources for oxidative DNA damage studies. The generation of hydroxyl radicals upon UVA irradiation (lambda = 350 nm) was verified by trapping experiments with 5,5-dimethyl-1-pyrroline N-oxide and benzene. The enzymatic assays of the damage in cell-free DNA from bacteriophage PM2 caused by the acridine and phenanthridine hydroperoxides 3 and 7 under near-UVA irradiation revealed a wide range of DNA modifications. Particularly, extensive single-strand break formation and DNA base modifications sensitive to formamidopyrimidine DNA glycosylase (Fpg protein) were observed. In the photooxidat…

Influence of peroxisome proliferators on phosphoprotein levels in human and rat hepatic-derived cell lines.

1995

To elucidate the effect of peroxisome proliferators on the signal-transduction pathway, we have compared the effect of ciprofibrate, an hypolipaemic agent, on the overall phosphoprotein level between rat and human well differentiated hepatic derived cell lines. The phosphorylation status of several phosphoproteins in the rat Fao cell line was increased by the drug while no changes were observed in the human HepG2 cell line. In rat Fao cells, this increase, which is concentration and time dependent, can be as much as eightfold for 20-kDa and 22-kDa proteins. Wy-14,643, a non-fibrate molecule and a more potent peroxisome proliferator than ciprofibrate, increased the phosphorylation status of …

Photochemical and Photobiological Studies of a Furonaphthopyranone as a Benzo-spaced Psoralen Analog in Cell-free and Cellular DNA

1997

Photobiological activities of the benzo-spaced psoralen analog furonaphthopyranone 3 have been investigated in cell-free and cellular DNA. The molecular geometry parameters of 3 suggest that it should not form interstrand crosslinks with DNA. With cell-free DNA no evidence for crosslinking but also not for monoadduct formation was obtained; rather, the unnatural furocoumarin 3 induces oxidative DNA modifications under near-UVA irradiation. The enzymatic assay of the photosensitized damage in cell-free PM2 DNA revealed the significant formation of lesions sensitive to formamidopyrimidine DNA glycosylase (Fpg protein). In the photooxidation of calf thymus DNA by the furonaphthopyranone 3, 0.2…

Effects of carboxyamidotriazole on in vitro models of imatinib-resistant chronic myeloid leukemia.

2008

Although imatinib mesylate (IM) has revolutionized the treatment of chronic myeloid leukemia (CML), some patients develop resistance with progression of leukemia. Alternative or additional targeting of signaling pathways deregulated in bcr-abl-driven CML cells may provide a feasible option for improving clinical response and overcoming resistance. In this study, we show that carboxyamidotriazole (CAI), an orally bioavailable calcium influx and signal transduction inhibitor, is equally effective in inhibiting the proliferation and bcr-abl dependent- and independent-signaling pathways in imatinib-resistant CML cells. CAI inhibits phosphorylation of cellular proteins including STAT5 and CrkL a…

Age-related and tissue-specific accumulation of oxidative DNA base damage in 7,8-dihydro-8-oxoguanine-DNA glycosylase (Ogg1) deficient mice.

2001

Mutations that influence the repair of oxidative DNA modifications are expected to increase the steady-state (background) levels of these modifications and thus create a mutator phenotype that predisposes to malignant transformation. We have analysed the steady-state levels and repair kinetics of oxidative DNA modifications in cells of homozygous ogg1(-/-) null mice, which are deficient in Ogg1 protein, a DNA repair glycosylase that removes the miscoding base 8-hydroxyguanine (8-oxoG) from the genome. Oxidative purine modifications including 8-oxoG were quantified by means of an alkaline elution assay in combination with Fpg protein, the bacterial functional analogue of Ogg1 protein. In pri…