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排序方式: 共有1422条查询结果,搜索用时 0 毫秒
1.
Xu Dai-gen He Han-zhen Zhang Guo-gao B. Gansewendt H. Peter H. M. Bolt 《华中科技大学学报(医学英德文版)》1993,13(2):100-104
Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from orgnas of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gaschro-matography/massspectrometry (GC/ MS). DNA adducts, 7-methylguanine (7-MeG) and O6-Methylguanine(08-MeG), incorporation of14C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA add,ue,ts in the studied organs was only quantitatively different. The formation of O6-MeG was further pioved by analysing the acidic hydrolysates using HPLC with non-radioactive O6MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis. 相似文献
2.
Balloon dacryocystoplasty: indications and contraindications 总被引:3,自引:0,他引:3
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4.
E. Hallier H. W. Goergens K. Hallier H. M. Bolt 《International archives of occupational and environmental health》1994,66(3):167-172
An intervention study was performed on 28 workers exposed by inhalation to styrene in the reinforced plastics industry and 20 controls not occupationally exposed to the compound. The workers involved were 14 laminators exposed to a time-weighted average of approximately 40 ppm styrene and 14 formers exposed to an average of about 10 ppm styrene. Ambient air monitoring data and the concentration of mandelic acid in the urine were used for the assessment of exposure. From each subject, peripheral blood lymphocytes were analysed for sister chromatid exchanges (SCEs). In the laminators, the mean SCE frequency was significantly higher than in the controls in both the group of smokers (9.59 ± 0.77 SCEs/cell vs 7.23 ± 1.00 SCEs/cell) and the group of non-smokers (10.25 ± 1.08 SCEs/cell vs 5.98 ± 0.60 SCEs/cell). The mean SCE frequency of the formers (7.42 ± 128 SCEs/cell in smokers) did not differ statistically from the controls (7.23 ± 1.00 SCEs/cell in smokers). No evaluation was made for non-smoking formers since all but one worker in this group were smokers. In order to comply with a lowering of the occupational exposure limit (MAK value) for occupational exposure to styrene in the Federal Republic of Germany from 100 ppm to 20 ppm, considerable technical and hygienic improvements were made at the work site of the laminators. This intervention led to a reduction of average exposure of these workers by inhalation from 40 ppm to approximately 20 ppm. One year after these improvements were made, a second investigation was performed. In all but one of the laminators, the concentration of mandelic acid in urine had dropped considerably. The SCE frequency in blood lymphocytes of the laminators had likewise dropped significantly to 7.74 ± 0.59 SCEs/cell in the non-smokers. In the smokers, it was also lower than on the first occasion (9.02 ± 1.19), yet statistical evaluation was not possible due to insufficient numbers. Overall, the results of the intervention study show that the lowering of the occupational exposure limit for styrene to 20 ppm in Germany was justified and that a reduction of occupational exposure to the chemical has led to a prevention of adverse cytogenetic effects. 相似文献
5.
H M Bolt 《Critical reviews in toxicology》1988,18(4):299-309
Cyclic DNA adducts bearing an "etheno" structure have been described to occur after interaction with metabolites of halogenated olefins. Extensive work has been published on adducts of vinyl chloride, both in vitro and in vivo. The major DNA adduct of vinyl chloride is 7-(2-oxoethyl)guanine, but an important minor adduct appears to be N2,3-ethenoguanine. Other etheno adducts, i.e., 1, N6-ethenoadenine and 3, N4-ethenocytosine, are readily formed with DNA, vinyl chloride, and a metabolizing system in vitro and with RNA in vivo, but usually are not detected as DNA adducts in vivo. Other compounds that have been studied with respect to possible formation of etheno DNA adducts are vinyl bromide (which is more or less completely analogous to vinyl chloride), acrylonitrile, vinyl acetate and vinyl carbamate. Proposals of possible structures of DNA adducts with an etheno structure have been promutagenic potential of these lesions which may lead to misincorporation of wrong DNA bases in newly synthesized DNA. 相似文献
6.
Ohne Zusammenfassung 相似文献
7.
HM Clink 《Journal of clinical pathology》1980,33(8):799-800
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9.
Semen parameters and testicular pathology in men with testicular cancer and contralateral carcinoma in situ or bilateral testicular malignancies 总被引:2,自引:2,他引:2
Kliesch S; Bergmann M; Hertle L; Nieschlag E; Behre HM 《Human reproduction (Oxford, England)》1997,12(12):2830-2835
We evaluated 14 patients with bilateral testicular tumour, one-sided tumour
and contralateral carcinoma in situ (CIS) of the testis or testis tumour in
single testis with respect to their fertility. We analysed semen
parameters, serum hormones [follicle-stimulating hormone (FSH), luteinizing
hormone (LH) and testosterone], testicular sonography, testicular volumes
and testicular histology prior to further anti-cancer treatment. Ten out of
14 patients showed normal or reduced sperm concentrations, while 4/14
patients were azoospermic. Serum FSH levels showed a significant negative
correlation with sperm concentrations in patients with testicular
malignancies (r = -0.64, P = 0.025). Testicular volumes revealed a
significant positive correlation with semen parameters in patients with
testes that were affected by CIS (r = 0.733, P = 0.038). We conclude that
even bilateral testicular cancer and/or CIS do not preclude fertility and,
therefore, patients should be offered andrological investigation and
therapy, including possibly surveillance strategy or the chance for
cryopreservation of the semen prior to further treatment in order to
preserve their chances for paternity.
相似文献
10.
Survey of CAG/CTG repeats in human cDNAs representing new genes: candidates for inherited neurological disorders 总被引:3,自引:2,他引:3
Neri C; Albanese V; Lebre AS; Holbert S; Saada C; Bougueleret L; Meier-Ewert S; Le Gall I; Millasseau P; Bui H; Giudicelli C; Massart C; Guillou S; Gervy P; Poullier E; Rigault P; Weissenbach J; Lennon G; Chumakov I; Dausset J; Lehrach H; Cohen D; Cann HM 《Human molecular genetics》1996,5(7):1001-1009