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排序方式: 共有766条查询结果,搜索用时 15 毫秒
761.
762.
U Ackermann D J Atchison L P Choo 《Canadian journal of physiology and pharmacology》1992,70(10):1403-1407
We tested the hypothesis that the atrial natriuretic peptide (ANP) mediated decrease in baroreceptor sensitivity that is seen in normal rats is more pronounced in a state of depressed cardiac performance. Holtzman rats (n = 15) were injected with Adriamycin (1 mg/kg i.p. 3 times/week for 8-10 weeks). Control rats (n = 17) were injected with 0.9% saline. Experiments were done in conscious animals that had been catheterized for i.v. infusions and for measurement of arterial blood pressure (ABP) and heart rate (HR). ANP (250 ng.kg-1.min-1) or saline vehicle was infused i.v. Graded periodic bolus injections of phenylephrine or sodium nitroprusside were given to assess baroreceptor sensitivity (beats.min-1.mmHg-1) up to 60 mmHg (1 mmHg = 133.3 Pa) above and below resting ABP. The following day the experiment was repeated with the ANP-vehicle regimen reversed. Finally, the rats were anesthetized and the rate of left ventricular pressure increase (dP/dt) was measured. Data evaluation included calculation of least squares linear regression slopes of peak delta HR vs. peak delta ABP, applying corrections for experimental errors in both the dependent and independent variables. Adriamycin rats (A) did not differ significantly from control rats (C) with respect to either initial ABP (A = 105 +/- 5; C = 100 +/- 3; mean mmHg +/- SEM) or initial HR (335 +/- 9 vs. 312 +/- 13 beats.min-1). However, their indices of cardiac performance were significantly depressed.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
763.
H H Lee J G Chang L S Lee S T Lin T M Ko K B Choo 《Proceedings of the National Science Council, Republic of China. Part B, Life sciences》1991,15(2):97-100
The polymerase chain reaction and oligonucleotide probe hybridization technique were applied to the detection of two common mutations of the beta-globin gene found in Chinese, namely the 4-base pair deletion at the 41-42 codons and the C to T substitution at nucleotide 654 of IVS-2. The accuracy of the method was established using beta-thalassemia cases with known mutations or haplotypes of the restriction fragment length polymorphism (RFLP). A further 11 cases of thalassemia intermediate and thalassemia minor were then analysed with the same approach. Our results showed that 5 of the 11 cases carried the TCTT-deletion at codons 41-42. Our method is economical both in terms of materials and time needed and in an alternative to the use of the molecular RFLP approach in the prenatal diagnosis of beta-thalassemia. 相似文献
764.
Biogenesis of mitochondria. oli2 Mutations affecting the coupling of oxidation to phosphorylation in Saccharomyces cerevisiae 总被引:3,自引:0,他引:3
M Murphy H Roberts W M Choo I Macreadie S Marzuki H B Lukins A W Linnane 《Biochimica et biophysica acta》1980,592(3):431-444
1. Two oligomycin-resistant strains of Saccharomyces cerevisiae have been isolated and shown to have mutations in the oli2 region of the mitochondrial DNA. On solid media containing a non-fermentable energy source, the mutant strains were able to grow only slowly at 28 degrees C and not at all at 18 degrees C or 36 degrees C. 2. When grown in a glucose-limited chemostat at 28 degrees C, the mutant strains were almost completely defective in oxidative metabolism. The mutant mitochondria contained significant levels of all respiratory enzymes, and an active, oligomycin-sensitive ATPase, but the ATP-32Pi exchange activity and P : O ratio were very low. 3. The mutations in these strains are genetically closely linked to mit mutations which have been shown to affect a 20 000-dalton ATPase subunit (Roberts, H., Choo, W.M., Murphy, M., Marzuki, S., Lukins, H.B. and Linnane, A.W. (1979) FEBS Lett. 108, 501-504). Since the mitochondrial ATPase in these mutant strains appears to be fully assembled, the defect in the coupling mechanism is probably a result of a small alteration in the structure of the 20 000-dalton ATPase subunit. 4. When the mutant strains were grown at 18 degrees C, the mitochondria had very low cytochrome oxidase activities, and reduced levels of cytochrome aa3. The largest subunit (Mr 40 000) of this enzyme was not synthesized. 相似文献
765.
Hyangsook Lee Maria Boile Sotirios Theofanis Sangho Choo Kang-Dae Lee 《Cluster computing》2014,17(3):835-847
The paper presents a multi-level hierarchical approach which models the oligopolistic behavior of carriers in maritime freight transportation networks. With the merger of the carriers’ industry and some dominant carriers in today’s shipping markets, carrier competition frequently exhibits an oligopolistic nature. This study considers the following three types of carriers; ocean carriers, land carriers, and port terminal operators. The oligopolistic ocean carriers, land carriers, and port terminal operators compete with each other in their pricing and routing decisions. The carriers determine service charges and delivery routes at different parts of the multi-modal freight network, creating hierarchical relationships. When using a game theoretic approach, ocean carriers become the leaders in an oligopoly shipping market. When dealing with individual carrier problems, the Nash equilibrium reveals the optimal decision where each carrier obtains the greatest profit. A three-level model is formulated to capture the interactions among different types of carriers. The validity and capability of the model gets demonstrated through an empirical example. 相似文献
766.