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801.
Abstract Isolated HeLa plasma membrane (PM) preparations and extracts containing either cell-surface proteins or lipids were examined for inhibition of adherence of radiolabeled Chlamydia trachomatis serovar E elementary bodies to glutaraldehydefixed HeLa monolayers. A dose-dependent adherence-inhibitory activity could be demonstrated with the PM. A urea extract as well as lipids from HeLa cells also inhibited chlamydial cytadherence. The inhibitory activity of the PM was trypsin-sensitive. It was absent when the urea extract was prepared from trypsin-treated HeLa cells. The urea extract was subjected to electrophoresis and protein blotting using a native gel system. Probing with radiolabeled chlamydial cytadhesin showed a single protein present in the urea extract that could represent a HeLa cell protein receptor for the chlamydiae. 相似文献
802.
We analysed the effects of nitrogen mustard (HN2) on the growth, cell cycle distributions, and ratios of tumour cells to host cells for MCa-11 tumours grown in vivo. Treatment of tumour-bearing BALB/c mice with 3 mg/kg of HN2 produced a significant slowing of MCa-11 tumour growth. Seventy-two hours after treatment in vivo with either 3 or 4 mg/kg of HN2, the host cells in the treated tumours showed a significantly decreased G0/G1 peak and an increased G2/M peak (P < 0.01), whereas the cancer cells in the treated tumours showed significant increases in the G0/G1 peak coupled with relatively decreased proportions of S and G2/M tumour cells (P < 0.001). The ratio of the total number of cancer cells to the total number of host cells in the tumours was significantly increased 72 h after HN2 administration (P<0.01). Thirty-two days after treatment with HN2, the cell cycle distributions of the host and tumour cells in the treatment and control tumours had returned to being identical, but the ratio of the total number of cancer cells to the total number of host cells remained increased in the treated tumours (P<0.01). These results show that the administration in vivo of HN2 can lead to entirely different cell cycle effects for the host and cancer cells in the same tumour, and that the partial growth arrest of MCa-11 tumours from HN2 treatment may be due in part to the preferential destruction of host cells rather than solely to a direct cytotoxic effect on the cancer cells. 相似文献
803.
Pseudomonas acidovorans contains putrescine, 2-hydroxyputrescine, and spermidine. 相似文献
804.
When wheat seedlings were grown in the presence of 62.5-500μM 4 chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone, an inhibitor of photosystem II electron transport, there was a marked
inhibition of in vivo photosystem II electron transport as revealed by the analysis of fast chlorophyll a fluorescence transients
in intact leaves and by the inhibition (95% at 500μM) of net photosynthesis in intact leaves Accompanying this inhibition of photosystem II electron transport, there was a decrease
in the content of photosynthetic pigments. The extent of lipid peroxidation, measured in terms of malondialdehyde content
was not increased; rather it was found decreased. An analysis of in vitro lipid peroxidation of the thylakoid membranes of
control and 4-chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone treated plants in the presence of a sensitizer dye (toluidine
blue) showed a similar rate both in the control and treated samples suggesting that the availability of unsaturated fatty
acids as a substrate for lipid peroxidation was not limiting even though it decreased in the treated plants. On the other
hand, it appears that the availability of the free radicals for lipid peroxidation was decreased byenhanced activity of the
enzyme systems involved in the metabolism of free radicals. Measurements of the activities of enzymes involved in the metabolism
of free radicals showed an increase in the activities of NADPH-glutathione reductase (6–8 fold) and catalase (15–30%) and
a decrease in the activity of superoxide dismutase (30–45%) in the treated plants. 相似文献
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