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A recently derived in vitro chemiluminescence assay (Salles et al. [1995]
Anal. Biochem., 232, 37-42) has been used to investigate the effects of a
panel of twenty-two anticancer drugs and certain antibiotics on the
excision repair activity of cell-free extracts from the human cell line,
HeLa. This methodology, termed the 3D (Damaged DNA Detection) assay, based
on the in vitro excision repair assay previously developed (Wood et al.
[1988] Cell, 53, 97-106) has provided data indicating definite in vitro
inhibition of DNA repair by actinomycin D, aphidicolin, doxorubicin,
distamycin A and mithramycin A. This assay therefore offers the potential
for identifying agents with the ability to inhibit DNA repair.
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A Mauskop BT Altura RQ Cracco BM Altura 《Cephalalgia : an international journal of headache》1994,14(1):24-28
The entity of chronic daily headache (CDH) is well documented, but is not included in the current classification. We divided patients with CDH into groups with and without migrainous features. This division resulted in clearly distinguishable syndromes of daily migrainous headaches (DMH) and daily tension-type headaches (DTH). Family history of headaches was more common in patients with DMH. Patients in both groups had a high incidence of caffeine or drug overuse. The clinical division into DMH and DTH was supported by our finding of a higher incidence of disturbed magnesium (Mg) metabolism in patients with DMH. Of 26 patients with DMH, 8 (30.8%) had low serum ionized, but not total, Mg levels, and 16 (61.5%) had high ionized calcium/magnesium ratios. The corresponding numbers for the 22 patients with DTH were 1 (4.5%) and 8 (30.4%). These new laboratory measurements offer possible biological markers for the diagnosis of different headache syndromes. 相似文献
116.
Differential expression of CYP1A1 and CYP1B1 in human breast epithelial cells and breast tumor cells 总被引:12,自引:9,他引:12
Spink DC; Spink BC; Cao JQ; DePasquale JA; Pentecost BT; Fasco MJ; Li Y; Sutter TR 《Carcinogenesis》1998,19(2):291-298
Human cytochromes P450 1A1 (CYP1A1) and P450 1B1 (CYP1B1) catalyze the
metabolic activation of a number of procarcinogens and the hydroxylation of
17beta-estradiol (E2) at the C-2 and C-4 positions, respectively. The
aromatic hydrocarbon receptor (AhR) agonist 2,3,7,8-
tetrachlorodibenzo-p-dioxin (TCDD) has a marked effect on estrogen
metabolism in MCF-7 breast-tumor cells by induction of these two enzymes.
To investigate whether induction of CYP1A1 and CYP1B1 by AhR agonists and
the associated increase in E2 metabolism are common to all breast
epithelial cells and breast-tumor cells, we determined the effects of TCDD
on E2 metabolism, and CYP1A1 and CYP1B1 mRNA levels in a series of
non-tumor-derived breast epithelial (184A1 and MCF-10A) and breast-tumor
(MCF-7, T-47D, ZR-75-1, BT-20, MDA-MB-157, MDA-MB-231 and MDA-MB-436) cell
lines. In 184A1 cells, which did not express detectable estrogen receptor
(ER) alpha mRNA, CYP1A1 mRNA and activity were induced by TCDD, and
enhanced E2 metabolism in TCDD-treated cells was predominantly E2
2-hydroxylation. In MCF-10A, MCF-7, T-47D, ZR-75-1 and BT-20 cells, which
expressed varying levels of ER alpha mRNA, both CYP1A1 and CYP1B1 mRNA
levels and rates of both E2 2- and 4- hydroxylation were highly elevated
following exposure to TCDD. In MDA- MB-157, MDA-MB-231 and MDA-MB-436
cells, which did not express detectable ER alpha mRNA and generally
displayed fibroblastic or mesenchymal rather than epithelial morphology,
CYP1B1 induction was favored, and the rate of E2 4-hydroxylation exceeded
that of 2- hydroxylation in TCDD-treated cells. These results show that
breast epithelial cells and tumor cells vary widely with regard to AhR-
mediated CYP1A1 and CYP1B1 induction, suggesting that factors in addition
to the AhR regulate CYP1A1 and CYP1B1 gene expression. In these cell lines,
significant CYP1A1 inducibility was restricted to cultures displaying
epithelial morphology, whereas CYP1B1 inducibility was observed in cells of
both epithelial and mesenchymal morphology.
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