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831.
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834.
835.
Evidence for the genetic control of the sodium pump density in HeLa cells 总被引:14,自引:1,他引:13
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1. HeLa cells were grown in normal and altered growth solutions; the ion contents, volumes, K sensitive ouabain binding, the Na-K-ATPase and the Na and K transport measured.2. Cells grown in 1 x 10(-4)M ethacrynate or low-K media for 24 hr have a raised [Na](i), a decreased [K](i), and an increased ouabain binding. Those grown in low-K also have an increased Na-K-ATPase activity.3. When cells are put into low-K solutions the [Na](i) initially rises to a high value, and then starts to fall some 8 hours later as the ouabain binding increases, suggesting that these additional sites represent working Na pumps. Flux measurements on low-K cells provide some support for this view.4. Experiments in which sorbitol replaced [Na](o) showed that the increased ouabain binding and Na-K-ATPase was related to the increase in [Na](i) rather than the decrease in [K](i) and was not due to a non-specific effect of [K](o) change.5. The protein synthesis inhibitors cycloheximide and puromycin stopped the effect of ethacrynate and low-K solutions on increased ouabain binding. They also decreased the ouabain binding and K influx in normal cells over 24 hr. Cycloheximide had similar effects on Na-K-ATPase in low-K treated and normal cells. These results suggest that protein synthesis is required for the appearance of more ouabain sensitive sites in the cell membrane, both in response to ethacrynate and low-K treatment and for normal replacement during the cell's life.6. The RNA synthesis inhibitors actinomycin D (AMD) and cordycepin had complex effects on ouabain binding in fresh and ethacrynate treated cells. These inhibitors increased the ouabain binding but decreased the K influx. This discrepancy was due to the appearance of ouabain binding sites with different characteristics from normal sites. A limited investigation of this phenomenon was carried out. Probably AMD stops the normal replacement of sites in the membrane.7. These results are consistent with the hypothesis that HeLa cells have a system for controlling the number of Na pumps in their membranes. This system responds to the level of [Na](i) within the cell and involves protein synthesis. It is not clear to what extent the nucleus is normally involved in this process. 相似文献
836.
Gram staining and bacterial culturing methods were used to determine the incidence of bacterial contamination of cellular blood components at the time of transfusion reactions. Over a 5-year period, 2208 (4.3%) of 51,278 transfusions were complicated by reactions. Overall bacterial contamination occurred in 5 (0.03%) of 17,928 transfusions of single- donor apheresis platelets, 1 (0.14%) of 712 transfusions of pooled random-donor platelet concentrates, 1 (0.003%) of 31,385 transfusions of red cells, and 0 of 1253 transfusions of fresh-frozen plasma. Gram staining done at the time of positive cultures was positive in three of six cases. Although six of seven recipients of contaminated components suffered no clinical sequelae, contaminated transfusions may have been a contributing cause of death in one case. Attempts were made to avoid the transfusion of contaminated cellular blood components by performing routine bacterial cultures: 0 of 341 quality control cultures were positive. To avoid the transfusion of contaminated platelets by identifying bacteria, Gram staining was performed in all single-donor apheresis platelet units collected on open systems and daily in platelets stored > 48 hours: 8 (0.15%) of 5334 smears done on 3829 platelet units were interpreted as positive, and those units were not transfused, but only two of eight units were culture positive. These studies suggest that bacterial contamination can result in adverse clinical sequelae in transfusion recipients and that both culturing and Gram staining are poor methods of screening for contaminated units. More sensitive and specific methods of generalized screening for bacterial contamination are needed. 相似文献
837.
An evaluation of a method of trochanteric fixation using three wires in the Charnley low friction arthroplasty 总被引:1,自引:0,他引:1
The crossed wire technique of trochanteric reattachment, with ambulation from the second day after the arthroplasty, resulted in 2.3% of complete detachments, and 2.7% of fibrous union at one year (total failure rate of 5%). Of 75 trochanters which had a fibrous union at 3 months, 2 later became completely detached, 27 remained as a fibrous union and 46 progressed to complete or partial bony union by one year. The incidence of defective trochanteric union was 2.3 times more frequent in arthroplasties performed by residents in training than it was in those performed by senior staff, (10.8% and 4.6% respectively at 3 months and 5.6% and 2.4% respectively at 12 months). The incidence of defective trochanteric union in bilateral arthroplasties was double the rate in unilateral operations, (14% and 7% respectively). Eighty-six and one half per cent of the arthroplasties which developed defective union of the trochanter showed follow-up radiographic evidence of defective fixation, though 13.5% were apparently satisfactory on discharge. Roughly 79% (79.2%) of the cases which developed defective union of the trochanter developed broken wires within one year of the arthroplasty. Relief from pain by total joint arthroplasty was not significantly influenced by defective trochanteric union (mean postoperative grade for pain 5.8). 相似文献
838.
P W Docherty J D Goodman J G Hill B G Pickles J Boardman C G Taylor P V Bush L E Skinner R C Slater 《British journal of obstetrics and gynaecology》1983,90(8):759-763
In a double blind trial, the effect of prophylactic low-dose subcutaneous heparin or saline on peri-operative blood loss was studied in 100 women undergoing abdominal hysterectomy. Mean blood loss was 401 (SEM 75) ml and 246 (SEM 15) ml in the women who received heparin or saline, respectively. Coagulation studies were carried out during the pre- and post-operative phases in order to assess the contribution of any coagulation abnormalities to operative blood loss. In identifying patients at risk, platelet function tests were of some value. 相似文献
839.
840.