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891.
目的观察SD大鼠麻醉后生化指标的变化。方法50只2月龄SPF级SD种大鼠,雄性28只,雌性22只,每鼠空腹16h,分别在麻醉后0、5、10和20min采血,检测血清ALT、AST、GLU、BUN、TP、ALB、AKP、CREA、CHOL、TG。结果随麻醉时间的延长,SD大鼠的生化指标有不同程度的变化。结论规范麻醉采血操作,缩短SD大鼠麻醉后等待采血的时间可减少生化指标的波动。 相似文献
892.
CIP耐药的铜绿假单胞菌两种分子耐药机制关系的研究 总被引:1,自引:0,他引:1
目的探讨环丙沙星(CIP)耐药的铜绿假单胞菌临床分离株主动外排药物与gyrA、parC基因突变的关系。方法联合碳酰氰基-对-氯苯腙(CCCP)和CIP对CIP耐药的铜绿假单胞菌株进行主动外排阳性株和阴性株的筛选,并对这些菌株的gyrA,parC基因进行聚合酶链式反应-限制性片段长度多态性分析(PCR—RFLP)。结果57%(55/97)的CIP耐药菌株最小抑菌浓度(MIC)可被逆转,gyrA单基因突变率为65%,gyrA和pa-C双基因突变率为35%,未发现parC单基因突变的菌株。主动外排阳性组与阴性组gyrA、parC基因突变情况差异无显著性。结论在本地区铜绿假单胞菌对CIP的耐药机制中,主动外排系统表达上调与抗菌药物作用靶位的改变均占有重要的地位,两者可能是并存的两种相对独立的机制。 相似文献
893.
Ambrus JI Kelso MJ Bremner JB Ball AR Casadei G Lewis K 《Bioorganic & medicinal chemistry letters》2008,18(15):4294-4297
The synthesis of 22 2-aryl-1H-indoles, including 12 new compounds, has been achieved via Pd- or Rh-mediated methodologies, or selective electrophilic substitution. All three methods were based on elaborations from simple indole precursors. SAR studies on these indoles and 2-phenyl-1H-indole in Staphylococcus aureus as NorA efflux pump inhibitors indicated 5-nitro-2-(3-methoxycarbonyl)phenyl-1H-indole was a slightly more potent inhibitor than the lead INF55. A promising new antibacterial lead compound against S. aureus (2-phenyl-1H-indol-5-yl)-methanol, was also found. 相似文献
894.
895.
Daniel V. Suzuki José M. Carter Maria Filomena A. Rodrigues Elda S. da Silva Alfredo E. Maiorano 《World journal of microbiology & biotechnology》2008,24(6):771-775
This work aimed at the study of purification of biopolymers produced by Burkholderia cepacia IPT64, through a chemical attack like an adjuvant procedure through chemical and enzymatic route. Enzymatic lysis using protease
was run on an enzyme/cell ratio of 0.02. Chemical attacks were performed as pre or post-treatment for enzymatic attacks, using
sodium dodecyl sulphate or hydrogen peroxide. The same chemicals and procedures were used alone as a control. Fenton’s reagent
was also tested as a chemical treatment. Using only one of the chemicals H2O2, Fenton’s reagent or SDS, the purity increase achieved values of 14%, 16% or 23%, respectively. When H2O2 or SDS were used as pre-treatment for the enzymatic attack, the results of purity increase achieved values of 58% for H2O2/cell ratio between 0.60 and 1.20, and 57% when SDS/cell ratio at 0.56 was used. In the case when H2O2 or SDS were used as post-treatment for the enzymatic attack, results of purity increase achieved 60% when the H2O2 was used at H2O2/cell ratio ranging between 0.30 and 0.60 and 71% when SDS was used at a ratio SDS/cell of 0.56. 相似文献
896.
Diederichs F 《Biophysical chemistry》2008,134(3):119-143
The present paper concerns with ion homeostatic reactions in view of stimulus-secretion coupling of the beta-cell, including Ca2+ fluxes of the endoplasmatic reticulum (ER). A steady state of cytosolic sodium and potassium ion concentrations ([Na+]c and [K+]c, respectively), and of the membrane potential (Delta c phi) can be attained only, if the flux through the electrogenic Na-K pump (JNaK) is balanced electrically, and if JNaK is rather high (about 25% of total ATP consumption at 10 mM glucose). Metabolically caused changes of cellular pH are unlikely, because, on the one hand, CO2 can rapidly leave the cell through cellular membranes, and because ATP cycling cannot produce nor consume protons. A slight decrease of pHc during cellular activity is caused mainly by an increased Ca-H exchange flux through the plasma membrane Ca2+ pump (J PMCA), which might be overcome, however, by H+ transport into secretory granules. The present simulations show that the conductance of ATP-sensitive K+ channels (K ATP) is highly susceptible to changes of [Mg2+]c. As a physical link between the Ca2+ filling state of the ER and the initiation of a depolarising, Ca2+ release-activated current (I CRAN), a metabolite (inositol 1,4,-diphosphate (IP2)) of the inositol 1,4,5-triphosphate (IP3) cycle is introduced. Sufficient ATP for insulin secretion is made available during glucose activation by [IP2] inhibition of a parallel [ATP]c consuming flux through protein biosynthesis (J Pbs). This leads to fast oscillations with a triphasic patterns of [Ca2+]c oscillations. Slow oscillations are initiated by including a Ca2+ leak current through highly uncoupled SERCA3 pumps. Both types of oscillations may superimpose yielding compound bursting and mixed oscillations of [Ca2+]c. 相似文献
897.
Responses of mycorrhizal jack pine (<Emphasis Type="Italic">Pinus banksiana</Emphasis>) seedlings to NaCl and boron 总被引:1,自引:0,他引:1
Mónica Calvo Polanco Janusz J. Zwiazek Melanie D. Jones Michael D. MacKinnon 《Trees - Structure and Function》2008,22(6):825-834
In earlier studies, we established that mycorrhizal associations protect plants against salt stress. However, elevated boron
levels are often present in saline soils and little is known about the effects of boron on salt resistance of mycorrhizal
plants. In the present study, we inoculated jack pine (Pinus banksiana) seedlings with Hebeloma sp., Suillus tomentosus and Wilcoxina mikolae var. mikolae to study the effects of mycorrhizal associations on seedling responses to boron and salt. Seedlings were grown in the greenhouse
and subjected to 60 mM NaCl, 2 mM H3BO3 or 60 mM NaCl + 2 mM H3BO3 treatments for 4 weeks. Dry weights, shoot:root ratios and chlorophyll concentrations were higher in inoculated seedlings
for all treatments compared with the non-inoculated plants. When applied with NaCl, B aggravated needle necrosis while reducing
Cl concentrations in shoots of non-inoculated plants. Plants treated with 2 mM H3BO3 + 60 mM NaCl had similar concentrations of Na and B to those that were treated separately with 60 mM NaCl and 2 mM H3BO3. Plants inoculated with mycorrhizal fungi had lower shoot Na concentrations compared with non-inoculated seedlings, but showed
relatively little impact from elevated B concentrations. 相似文献
898.
Daniella Bonaventura Claure N. Lunardi Gerson J. Rodrigues Mrio A. Neto Lusiane M. Bendhack 《Nitric oxide》2008,18(4):287-295
Sodium nitroprusside (SNP) is an endothelium-independent relaxant agent and its effect is attributed to its direct action on the vascular smooth muscle (VSM). Endothelium modulates the vascular tone through the release of vasoactive agents, such as NO. The aim of this study was to investigate the contribution of the endothelium on SNP vasorelaxation, NO release and Ca2+ mobilization. Vascular reactivity experiments showed that endothelium potentiates the SNP-relaxation in rat aortic rings and this effect was abolished by l-NAME. SNP-relaxation in intact endothelium aorta was inhibited by NOS inhibitors for the constitutive isoforms (cNOS). Furthermore, endogenous NO is involved on the SNP-effect and this endogenous NO is released by cNOS. Moreover, Ca2+ mobilization study shows that l-NAME inhibited the reduction of Ca2+-concentration in VSM cells and reduced the increase in Ca2+-concentration in endothelial cells induced by SNP. This enhancement in Ca2+-concentration in the endothelial cells is due to a voltage-dependent Ca2+ channels activation. The present findings indicate that the relaxation and [Ca2+]i decrease induced by SNP in VSM cells is potentiated by endothelial production of NO by cNOS-activation in rat aorta. 相似文献
899.
900.
This paper investigates the impact of increased salinity on touch-induced receptor and action potentials of Chara internodal cells. We resolved underlying changes in ion transport by current/voltage analysis. In a saline medium with a low Ca(2+) ion concentration [(Ca(2+))(ext)], the cell background conductance significantly increased and proton pump currents declined to negligible levels, depolarizing the membrane potential difference (PD) to the excitation threshold [action potential (AP)(threshold)]. The onset of spontaneous repetitive action potentials further depolarized the PD, activating K(+) outward rectifying (KOR) channels. K(+) efflux was then sustained and irrevocable, and cells were desensitized to touch. However, when [Ca(2+)](ext) was high, the background conductance increased to a lesser extent and proton pump currents were stimulated, establishing a PD narrowly negative to AP(threshold). Cells did not spontaneously fire, but became hypersensitive to touch. Even slight touch stimulus induced an action potential and further repetitive firing. The duration of each excitation was extended when [Ca(2+)](ext) was low. Cell viability was prolonged in the absence of touch stimulus. Chara cells eventually depolarize and die in the saline media, but touch-stimulated and spontaneous excitation accelerates the process in a Ca(2+)-dependent manner. Our results have broad implications for understanding the interactions between mechano-perception and salinity stress in plants. 相似文献