Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043346 (xeroderma pigmentosum)
 2,924 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clonogenic survival response to 254-nm ultraviolet light was measured in 2 strains of repair-proficient normal human fibroblasts and 4 strains of xeroderma pigmentosum (XP) fibroblasts belonging to complementation groups A, C, D and variant. In all strains except XPA, cells irradiated in plateau phase and subcultured immediately were much more resistant to the lethal effect of UV than cells irradiated in the exponential phase of growth. Typically, 10-20% of plateau-phase cells were extremely resistant. When the cultures were held in plateau phase for 24 h after irradiation and before subculture, there was a further enhance of survival. By use of a UV-specific endonuclease assay, no difference was found in the number of DNA lesions induced in exponentially growing and plateau cultures by the same dose of UV light. Thus plateau-phase cells appear to be more efficient in their DNA-repair capability than cells in exponential growth. XP group A cells were uniquely found to be deficient in the processes which lead to plateau-phase resistance. Since plateau-phase repair was not lacking in XP groups C, D and variant, it may be related to a DNA-repair process different from that which is responsible for the overall UV sensitivity of these cells.
 ...
PMID:Resistance of plateau-phase human normal and xeroderma pigmentosum fibroblasts to the cytotoxic effect of ultraviolet light. 52 80

Human cells (normal and xeroderma pigmentosum variant) irradiated with ultraviolet light and pulse-labelled with [3H]thymidine underwent transient decline and recovery of molecular weights of newly synthesized DNA and rates of [3H]thymidine incorporation. The ability to synthesize normal-sized DNA recovered more rapidly in both cell types than thymidine incorporation. During recovery cells steadily increased in their ability to replicate normal-sized DNA on damaged templates. The molecular weight versus time curves fitted exponential functions with similar rate constants in normal and heterozygous xeroderma pigmentosum cells, but with a slower rate in two xeroderma pigmentosum variant cell lines. Caffeine added during the post-irradiation period eliminated the recovery of molecular weights in xeroderma pigmentosum variant but not in normal cells. The recovery of the ability to synthesize normal-sized DNA represents a combination of a number of cellular regulatory processes, some of which are constitutive, and one of which is altered in the xeroderma pigmentosum variant such that recovery becomes slow and caffeine sensitive.
 ...
PMID:Xeroderma pigmentosum variants have a slow recovery of DNA synthesis after irradiation with ultraviolet light. 53 35

AF 2 (2-(2-furyl)-3-(5-nitro-furyl)acrylamide) was toxic to Chinese hamster V 79 cells and normal human fibroblasts in aerobic media. However, the toxicity of the drug was increased many times by hypoxia. Similarly, the frequency of AF 2-induced azaguanine- and ouabain-resistant mutants of V 79 cells was much higher in hypoxia than under aerobic conditions. Both hamster V 79 cells and human fibroblasts metabolized AF 2 and other nitrofurans rapidly only under hypoxic conditions. Human fibroblasts were more sensitive to AF 2 both under aerobic conditions and in hypoxia than were V 79 cells under similar conditions. The Chinese hamster cells consistently gave survival curves with marked shoulders while human cells did not. Aerobic cultures of fibroblasts derived from xeroderma pigmentosum (XP) patients were markedly sensitive to AF 2 while fibroblasts from two ataxia telangeictasia patients had normal sensitivity. Under hypoxic conditions the sensitivity of both types of cells was increased but the XP line remained 5--10-fold more sensitive than normal or ataxia cells. These results suggest that the DNA lesions produced by AF 2 may be regarded as similar to those produced by ultraviolet light, at least in terms of their repairability in human cells.
 ...
PMID:The action of AF 2 on cultured hamster and human cells under aerobic and hypoxic conditions. 56 38

The role of DNA repair mechanisms in the induction of sister chromatid exchanges (SCE) after exposure to ultraviolet radiation was investigated in xeroderma pigmentosum cells. Cells from different excision-deficient XP strains, representing the 5 complementation groups in XP, A, B, C, D and E, and from excision-proficient XP variant strains were irradiated with low doses of UVR (0-3.5 J/m2). The number of SCE was counted after two cycles in the presence of BUdR. In cells of the complementation groups A, B, C and D the number of SCE was significantly higher than in UV-exposed control cells. The frequencies of SCE in group E cells and in XP varient cells were not different from those in control cells. Treatment with caffeine (0-200 microgram/ml) did not result in a different response of variant cells compared with normal cells. A simple correlation between SCE frequency and residual excision-repair activity was not observed. The response of the excision-repair deficient cells suggest that unrepaired damage, produced by UVR is involved in the production of SCE.
 ...
PMID:Induction of sister chromatid exchanges in xeroderma pigmentosum cells after exposure to ultraviolet light. 59 87

An endonuclease activity isolated from normal, Xeroderma Pigmentosum and De Sanctis-Cacchione fibroblasts by DNA-cellulose chromatography has been evaluated by means of sedimentation analysis both in alkaline and neutral sucrose gradients. The partially purified enzyme is active at pH 7.5 in presence of Mg++ and cleaves UV-irradiated and alkylated DNA. Under identical experimental conditions, the enzyme is not active on untreated, depurinated and heat-denaturated DNA. The specificity on pyrimidine dimers has been further investigated to understand the mechanism of action of the enzyme.
 ...
PMID:Cleavage of damaged DNA by an enzymatic activity from human fibroblasts. 61 1

The clastogenic effect of mitomycin C (MC) was determined in two normal fibroblast cell lines and two xeroderma pigmentosum (XP) cell lines, a variant and a group A excision-deficient line. The group A xeroderma cell line was substantially more sensitive to MC than either the XP variant or the normal human cells. On caffeine post-treatment potentiation of the MC-induced aberration frequency occurred in all the cell lines. The XP variant cell line exhibited a distinctly higher sensitivity to caffeine than the classical XP or the normal human cell line.
 ...
PMID:The influence of caffeine on the mitomycin C-induced chromosome aberration frequency in normal human and xeroderma pigmentosum cells. 62 79

Bloom's syndrome lymphocytes, which are characterized by a high incidence of sister chromatid exchanges (SCE: 80.6 per cell), were treated with mitomycin C (MMC) and the effect of the chemical on SCE frequency compared with that in normal cells. Raising the concentration of MMC from 1 X 10(-9) to 1 X 10(-7) g/ml led to about 10-fold increase (61.7 SCE per cell) in the SCE frequency over the base line in normal lymphocytes (6.4 SCE per cell), though chromosome aberrations remained at a relatively low frequency. MMC caused about a two-fold rise in SCE in cells of Bloom's syndrome (128.8 SCE at 10(-9) g/ml; 139.3 SCE at 10(-8) g/ml). The frequency of chromosome aberrations in Bloom's syndrome cells at concentrations of MMC of 1 X 10(-9) and 1 X 10(-8) g/ml was 0.350 and 0.825 per cell, respectively, and low when compared to the increased number of SCE. The increased frequency of SCE in normal and Bloom's syndrome cells is in contrast to the reported findings with cells from Fanconi's anemia and xeroderma pigmentosum. The distribution of SCE in MMC-treated normal cell correlates with that of spontaneous SCE in cells of Bloom's syndrome.
 ...
PMID:Effects of mitomycin C on sister chromatid exchange in normal and Bloom's syndrome cells. 62

At doses varying from 8 x 10(-5) to 3 x 10(-3) M sodium selenite (Na2SeO3) induced DNA fragmentation, DNA-repair synthesis, chromosome aberrations and a mitotic inhibition in cultured human fibroblasts. The response of DNA repair-deficient xeroderma pigmentosum (XP) fibroblasts to selenite is comparable to that of control cells. Incubation with mouse liver S-9 microsomal fraction increased the capacity of selenite to induce chromosome aberrations, DNA-repair synthesis and a lethal effect. XP cells behaved as control cells when treated with activated selenite. Sodium selenate (Na2SeO4) at doses ranging from 8 x 10(-5) to 3 x 10(-3) M could not be activated by incubating with a S-9 preparation. Selenate had the capacity to induce a small but significant DNA-repair synthesis.
 ...
PMID:The mutagenicity and cytotoxicity of selenite, "activated" selenite and selenate for normal and DNA repair-deficient human fibroblasts. 63 5

Several autosomal recessive diseases are associated with apparent DNA repair defects in cell culture. It seemed likely that a defect in excision repair reported for ataxia telangiectasia cells might reflect a lack of apurinic endonuclease activity. We report here normal levels of apurinic endonuclease activity in extracts of cell lines derived from patients with ataxia telangiectasia, xeroderma pigmentosum (complementation group D), Cockayne dwarfism, Fanconi anemia and Bloom syndrome.
 ...
PMID:Apurinic DNA endonuclease activities in repair-deficient human cell lines. 63 94

Xeroderma pigmentosum (XP) cells proficient in the excision repair of pyrimidine dimers (XP variants) were also found to be proficient in the excision repair of N-2-acetoxyacetylaminofluorene (AAAF)-induced lesions in their DNA, as assayed by the photolysis of 5-bromodeoxyuridine incorporated during repair. However, the time in which the small segments of newly synthesized DNA, made immediately after treatment of cells with AAAF, were joined together to form DNA of parental size by a process called postreplication repair was long in the XP variant and classical cells. Although increasing doses of AAAF increased the time for making daughter DNA of parental size for variant and classical XP cells, AAAF did not appear to affect this process in normal human cells. Treatment of variant and classical XP cells with a relatively small dose (2.5 micron) of AAAF or 2.5 J/sq m of UV radiation several hr before a 2- to 3-fold-larger dose decreased the time for the pulse-labeled DNA to appear as parental size.
 ...
PMID:Defective and enhanced postreplication repair in classical and variant xeroderma pigmentosum cells treated with N-acetoxy-2-acetylaminofluorene. 63 41


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>