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J L Vargas E O'Connor E Roche E Knecht S Grisolia 《Biochemical and biophysical research communications》1987,147(2):535-541
Many functional, morphological and biochemical differences among hepatocytes from different acinar zones have been described. Therefore, it will facilitate studies on liver metabolism rapid, non-destructive procedures to isolate hepatocytes from these zones. Flow cytometry is a new powerful tool which, however, has not been used thus far to accomplish the separation of hepatocytes from different acinar zones. We describe here various cytometric parameters which characterize hepatocyte populations, separated by isopycnic centrifugation in Percoll gradients. The intraacinar origin of the different hepatocytes was assessed by enzymatic and morphological measurements. 相似文献
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Exploring molecular mechanisms in chemically induced cancer: complementation of mammalian DNA repair defects by a prokaryotic gene 总被引:1,自引:0,他引:1
G P Margison J Brennand C H Ockey P J O'Connor 《BioEssays : news and reviews in molecular, cellular and developmental biology》1987,6(4):151-156
Exposure of man to chemical agents can occur intentionally, as in the treatment of disease, or inadvertently because the environment contains a wide range of synthetic or naturally occurring chemicals. The alkylating agents are a diverse group of compounds (Fig. 1) and comprise a good example of such xenobiotics, since much is known about their occurrence, and their biological effects include carcinogenicity, mutagenicity, toxicity and teratogenicity. Exposure to potentially carcinogenic alkylating agents such as nitrosamines may occur occupationally, from cigarette smoke, from certain foodstuffs and even endogenously through the ingestion of the appropriate precursor chemicals.1 At the other extreme, the cytotoxic effects of agents such as the chloroethylating nitrosamides or mustards have been exploited in the design of certain antitumour drugs.2 The effectiveness of antitumour agents and the other, mostly adverse, biological effects of alkylating agents have been ascribed to their ability to damage cellular macromolecules, in particular DNA. This review concentrates on investigations carried out over the past two years on the role of DNA damage in carcinogenesis, but we shall see how recent advances in this area of research have also led to a better understanding of the mechanisms of the cytotoxic effects of alkylating antitumour agents. 相似文献
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Cultured epithelial autografts for giant congenital nevi 总被引:3,自引:0,他引:3
G G Gallico N E O'Connor C C Compton J P Remensnyder O Kehinde H Green 《Plastic and reconstructive surgery》1989,84(1):1-9
Eight pediatric patients with giant congenital nevi confluent over 21 to 51 percent body surface area were treated by excision and grafting. The nevus was excised to the muscle fascia, and the open wound was grafted with cultured epithelial autografts and split-thickness skin grafts. The patients have been followed from 17 to 56 months. Seventeen operations were performed in the eight patients, excising a mean of 6.9 percent body surface area at each procedure. The mean duration of anesthesia was 3.7 hours, and the mean operative blood loss was 12.3 percent estimated blood volume. The mean "take" for the cultured epithelial autografts was 68 percent, and for the split-thickness skin grafts, 84 percent. Epithelialization of open wound areas adjacent to the grafts was somewhat slower for the cultured epithelial autografts than for the split-thickness skin grafts, but it led to a healed wound in all patients except one. Ten of the 17 areas grafted with cultured epithelial autografts resulted in small open wounds that required regrafting. Wound contraction under the cultured epithelial autografts and under split-thickness skin grafts was similar and depended more on the anatomic site grafted than on the type of graft employed. in 16 of 17 operations, the cultured epithelium remained as a permanent, durable skin coverage. The use of cultured epithelial autografts allowed a larger area of excision than would have been possible with split-thickness skin grafts alone and, therefore, a more rapid removal of nevus. Cultured epithelial autograft are an important new technique in the care of patients with giant congenital nevi. 相似文献
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OBJECTIVE--To survey sanitation facilities in schools in Bloomsbury health district. DESIGN--Postal questionnaire. SETTING--Inner London health district. PARTICIPANTS--School nurses. RESULTS--16 of 17 school nurses responded (37 of 41 schools). Fifteen schools did not have the minimum number of toilets and hand basins established in the Education (School Premises) Regulations 1981. In two schools toilets were kept locked for most of the day. In 10 schools toilet paper was not always available, and three of five secondary schools did not have disposal units for sanitary towels in the girls'' toilet areas. In 18 of the schools the toilets were not kept adequately clean. CONCLUSIONS--These conditions raise serious questions about environmental health, with the potential for the spread of infectious diseases, and undermine attempts to teach children basic hygiene. Health professionals have an important role in assessing health and safety standards in schools and ensuring that necessary improvements are made. 相似文献
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The level of nonprotein thiols was assayed in individual mammalian cells using flow cytometry. Previous determinations of glutathione (GSH, the most abundant nonprotein thiol in most cells) by flow cytometry were based on UV laser excitation of fluorochromes. Because of several shortcomings of UV excitation, an assay for GSH using visible light is of interest. Selective staining of nonprotein thiols with mercury orange (a mercurial compound that binds stoichiometrically to sulfhydryl groups) was obtained by restricting the staining time. By using various drugs that affect GSH levels and overall thiol levels in cells, it was shown that GSH is the primary thiol group being stained. Thus a quick, specific technique using mercury orange has been developed for the flow cytometric determination of nonprotein thiols and preferentially for GSH in individual mammalian cells. 相似文献
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3H]U-69593 labels a subtype of kappa opiate receptor with characteristics different from that labeled by [3H]ethylketocyclazocine 总被引:1,自引:0,他引:1
[3H]U-69593 is an opiate agonist that has been reported to bind in vitro with high affinity and selectivity to the kappa receptor subtype. The studies reported here were designed to determine the optimal conditions for labeling kappa receptors with [3H]U-69593 and to further characterize the binding site. The effects of temperature and NaCl on [3H]U-69593 binding were of particular interest because previous studies reported that [3H]ethylketocyclazocine ([3H]EKC) and [3H]bremazocine binding to kappa receptors was optimal at 4 degrees C in the presence of NaCl. Those conditions were not found to be optimal for [3H]U-69593 binding. Although the pharmacological specificity and Bmax of [3H]U-69593 binding was similar at room temperature and at 4 degrees C, the binding affinity was approximately three times lower at 4 degrees C than at room temperature. In addition, NaCl had an effect on [3H]U-69593 binding that was opposite that on [3H]EKC binding at 4 degrees C (100 nM DAGO and 100 nM DADLE were included in all [3H]EKC assays to prevent binding to mu and delta receptors), i.e. NaCl decreased, rather than increased, [3H]U-69593 binding at 4 degrees C. These differences between [3H]U-69593 and [3H]EKC binding at 4 degrees C were accentuated by a vast difference in the density of the binding sites [Bmax approximately equal to 12 fmol/mg protein for [3H]U-69593 vs approximately equal to 375 fmol/mg protein for [3H]EKC at 4 degrees C in the presence of NaCl) and suggested that [3H]U-69593 might bind selectively to a kappa receptor subtype. This concept was supported by competition experiments. In particular, the site labeled by [3H]EKC at 4 degrees C was found to be relatively insensitive (compared to [3H]U-69593 and [3H]EKC binding at room temperature) to the kappa agonist U-50488H, a close analog to U-69593. Based on these findings, we propose that [3H]U-69593 (and U-50488H) labels a kappa receptor subtype which differs from that labeled by [3H]EKC at 4 degrees C. 相似文献