排序方式: 共有39条查询结果,搜索用时 15 毫秒
1.
Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium 总被引:13,自引:9,他引:4
下载免费PDF全文
![点击此处可从《The Journal of general physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel. 相似文献
2.
We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperating multi-finger robots is derived considering the force and acceleration relationships between the fingers and the object to be handled. From the dynamic equation, maximum translational and rotational acceleration bounds of an object are calculated under given constraints of contact conditions, configurations of fingers, and bounds on the torques of joint actuators for each finger. Here, the rotational acceleration bounds can be applied as an important manipulability index when the multi-finger robot grasps an object. To verify the proposed method, we used a set of case studies with a simple multi-finger mechanism system. The achievable acceleration boundary in task space can be obtained successfully with the proposed method and the acceleration boundary depends on the configurations of fingers. 相似文献
3.
4.
5.
S Patyar R Joshi DS Prasad Byrav A Prakash B Medhi BK Das 《Journal of biomedical science》2010,17(1):21
Resistance to conventional anticancer therapies in patients with advanced solid tumors has prompted the need of alternative
cancer therapies. Moreover, the success of novel cancer therapies depends on their selectivity for cancer cells with limited
toxicity to normal tissues. Several decades after Coley's work a variety of natural and genetically modified non-pathogenic
bacterial species are being explored as potential antitumor agents, either to provide direct tumoricidal effects or to deliver
tumoricidal molecules. Live, attenuated or genetically modified non-pathogenic bacterial species are capable of multiplying
selectively in tumors and inhibiting their growth. Due to their selectivity for tumor tissues, these bacteria and their spores
also serve as ideal vectors for delivering therapeutic proteins to tumors. Bacterial toxins too have emerged as promising
cancer treatment strategy. The most potential and promising strategy is bacteria based gene-directed enzyme prodrug therapy.
Although it has shown successful results in vivo yet further investigation about the targeting mechanisms of the bacteria are required to make it a complete therapeutic approach
in cancer treatment. 相似文献
6.
BK. Binukumar Varsha Shukla Niranjana D. Amin Philip Grant M. Bhaskar Susan Skuntz Joseph Steiner Harish C. Pant 《Molecular biology of the cell》2015,26(24):4478-4491
Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by the loss of dopamine neurons in the substantia nigra, decreased striatal dopamine levels, and consequent extrapyramidal motor dysfunction. Recent evidence indicates that cyclin-dependent kinase 5 (Cdk5) is inappropriately activated in several neurodegenerative conditions, including PD. To date, strategies to specifically inhibit Cdk5 hyperactivity have not been successful without affecting normal Cdk5 activity. Previously we reported that TFP5 peptide has neuroprotective effects in animal models of Alzheimer’s disease. Here we show that TFP5/TP5 selective inhibition of Cdk5/p25 hyperactivation in vivo and in vitro rescues nigrostriatal dopaminergic neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP/MPP+) in a mouse model of PD. TP5 peptide treatment also blocked dopamine depletion in the striatum and improved gait dysfunction after MPTP administration. The neuroprotective effect of TFP5/TP5 peptide is also associated with marked reduction in neuroinflammation and apoptosis. Here we show selective inhibition of Cdk5/p25 hyperactivation by TFP5/TP5 peptide, which identifies the kinase as a potential therapeutic target to reduce neurodegeneration in Parkinson’s disease. 相似文献
7.
BK McNab 《New Zealand journal of zoology.》2016,43(2):179-190
The energy expenditure of the tūī (Prosthemadera novaeseelandiae), a meliphagid endemic to New Zealand, was measured and compared with 20 species of honeyeaters (family Meliphagidae) to determine whether its expenditure is influenced either by life in a moist, temperate climate or an island residence. Body mass in the honeyeaters accounted for 91.5% of the variation in basal rate. The combination of body mass, climate and the maximal limit to an altitudinal distribution explained 98.6% of the variation in basal rate with tropical, low-altitude species having the highest mass-independent rate. The basal rates of meliphagids in tropical highlands are similar to those in temperate lowlands, which may reflect similar food supplies. The tūī mass-independent expenditure appears to reflect an active lifestyle in a temperate climate with no evidence that an island residence influenced its rate, whereas sedentary birds on New Zealand have responded to island life with a depressed basal rate. An effective analysis of the variation in energy expenditure requires the inclusion of the ecological and behavioural characteristics that distinguish species. 相似文献
8.
9.
Callus was initiated from immature leaf and stem segments of rose (Rosa hybrida cv. Landora) and subcultured every four weeks on a basal medium of half-strength Murashige & Skoog (1962) salts plus 30 g l-1 sucrose (1/2 MS) and supplemented with 2.2 M BA, 5.4 M NAA and 2.2–9.0 M 2,4-D. Embryogenic callus and subsequently somatic embryos were obtained from 8-week-old callus culture on 1/2 MS+2.2 M BA+0.05 M NAA+0.3 M GA3+200–800 mg l-1 L-proline. Long-term cultures were established and maintained for up to 16 months by repeated subculture of embryogenic callus on L-proline deficient medium. About 12% of cotyledonary stage embryos taken from cultures cold-stored at 8±1°C for 4 days germinated on 1/2 MS+2.2 M BA+0.3 M GA3+24.7 M adenine sulphate.Abbreviations BA
benzyladenine
- NAA
-naphthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- GA3
gibberellic acid 相似文献
10.
Marine derivatives are of great pharmaceutical interest as inhibitory compound and search of bioactive compounds from Marine
organism which is relatively new to medicinal chemistry. Our main aim in the study is to screen possible inhibitors against
CCR5 which acts as co-receptor M-tropic HIV-1, through virtual screening of 122 Marine derived compounds from various
organisms known to have biological activity. Homology Model of CCR5 was constructed using MODELLER and the Model was energy
minimized and validated using PROCHECK to obtain a stable structure, which was further used for virtual screening of Marine
derived compounds through molecular Docking studies using GOLD. The Docked complexes were validated and Enumerated based on
the GOLD Scoring function to pick out the best Marine inhibitor based on GOLD score. Thus from the entire 122 Marine
compounds which were Docked, we got best 4 of them with optimal GOLD Score.
(LAMIVUDINE: 45.0218, BATZELLINE-D: 44.3852.ACYCLOVIR: 43.1362 and THIIOACETAMIDE: 42.7412) Further the Complexes were analyzed
through LIGPLOT for their interaction for the 4 best docked Marine compounds. Thus from the Complex scoring and binding ability its
deciphered that these Marine compounds could be promising inhibitors for M-tropic HIV-1 using CCR5 as Drug target yet pharmacological
studies have to confirm it. 相似文献