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91.
We have studied the functional effects of extracellular Cd(2+) on human ether-a-go-go-related gene (HERG) encoded K(+) channels. Low concentrations (10-200 &mgr;M) of extracellular Cd(2+) increased outward currents through HERG channels; 200 &mgr;M Cd(2+) more than doubled HERG currents and altered current kinetics. Cd(2+) concentrations up to 200 &mgr;M did not change the voltage dependence of channel activation, but shifted the voltage dependence of inactivation to more depolarized membrane potentials. Cd(2+) concentrations >/=500 &mgr;M shifted the voltage dependence of channel activation to more positive potentials. These results are consistent with a somewhat specific ability of Cd(2+) to destabilize the inactivated state. We tested the hypothesis that channel inactivation is essential for Cd(2+)-induced increases in HERG K(+) currents, using a double point mutation (G628C/S631C) that diminishes HERG inactivation (Smith, P. L., T. Baukrowitz, and G. Yellen. 1996. Nature (Lond.). 379:833-836). This inactivation-removed mutant is insensitive to low concentrations of Cd(2+). Thus, Cd(2+) had two distinct effects on HERG K(+) channels. Low concentrations of Cd(2+) caused relatively selective effects on inactivation, resulting in a reduction of the apparent rectification of the channel and thereby increasing HERG K(+) currents. Higher Cd(2+) concentrations affected activation gating as well, possibly by a surface charge screening mechanism or by association with a lower affinity site. 相似文献
92.
93.
Y Novik LM Ryan DG Haller R Asbury JP Dutcher A Schutt 《Cancer immunology, immunotherapy : CII》1999,16(4):261-266
The study was a Phase II randomized study to evaluate the efficacy of new agents for the treatment of advanced gastric carcinoma.
Patients were randomized to receive single agent chemotherapy with mitoxantrone, etoposide, aclacinomycin-A or spirogermanium.
The patients were stratified by prior use of chemotherapy, prior doxorubicin use and ECOG performance status. Patients with
a history of cardiac disease or prior doxorubicin exceeding a dose of 400 mg/m2 were restrictively randomized to sopirogermanium or etoposide only. One hundred and fourteen patients were registered for
the study. Among 98 evaluable patients there were only two partial responses (both in the etoposide arm), and one complete
response in the mitoxantrone arm. The median survival on the study was 3.3 months. One hundred and six patients were analyzable
for toxicity. There were four treatment-related deaths and four life-threatening toxicities. Because of low response rates
and relatively high toxicities the studied compounds were not deemed worth further investigation for advanced gastric cancer. 相似文献
94.
95.
96.
Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy 总被引:3,自引:0,他引:3
Transferrin, a glycoprotein involved in iron transport in body fluids, was
isolated from amniotic fluid of a hydramniospatient by sequential
anion-exchange chromatography and gel filtration. The N-glycans of human
amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F
digestion, isolated by gel filtration and fractionated by (high-pH)
anion-exchange chromatography. After alkaline borohydride treatment of
native hAFT, the released O-glycans were isolated by gel filtration and
fractionated by anion-exchange chroma-tography. Structure elucidation of 14
N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy.
Besides conventional N-glycans established earlier for human serum
transferrin (hST), new (alpha1-3)-fucosylated N- glycans were found,
representing sialyl Le(x) elements. Furthermore, as compared to hST, a
higher degree of (alpha1-6)-fucosylation and an increase in branching from
di- to triantennary compounds has been detected. The presence of O-glycans
is demonstrated for the first time in transferrin.
相似文献
97.
The robustness of two phylogenetic methods: four-taxon simulations reveal a slight superiority of maximum likelihood over neighbor joining 总被引:6,自引:3,他引:3
The robustness (sensitivity to violation of assumptions) of the maximum-
likelihood and neighbor-joining methods was examined using simulation.
Maximum likelihood and neighbor joining were implemented with Jukes-
Cantor, Kimura, and gamma models of DNA substitution. Simulations were
performed in which the assumptions of the methods were violated to varying
degrees on three model four-taxon trees. The performance of the methods was
evaluated with respect to ability to correctly estimate the unrooted
four-taxon tree. Maximum likelihood outperformed neighbor joining in 29 of
the 36 cases in which the assumptions of both methods were satisfied. In
133 of 180 of the simulations in which the assumptions of the
maximum-likelihood and neighbor-joining methods were violated, maximum
likelihood outperformed neighbor joining. These results are consistent with
a general superiority of maximum likelihood over neighbor joining under
comparable conditions. They extend and clarify an earlier study that found
an advantage for neighbor joining over maximum likelihood for
gamma-distributed mutation rates.
相似文献
98.
C Tardif H Maamar M Balfin JP Belaich 《Journal of industrial microbiology & biotechnology》2001,27(5):271-274
Electropermeabilization of Clostridium cellulolyticum was optimized using ATP leakage assays. Electrotransformation was then performed under optimized conditions (6 to 7.5 kV
cm−1 field strength applied during 5 ms to a mixture containing methylated plasmids and late exponential phase cell suspensions
(10 molecules:1 cell) in a sucrose-containing buffer). Transformants were only obtained when 7 or 7.5 kV cm−1 pulses were applied. Transformation efficiencies evaluated from the growth curves of transformed cells were between 105 and 107 transformants per microgram of plasmid DNA for five different replicon-based plasmids. Restriction nuclease digestion patterns
of pJIR418 purified from transformed Clostridia and Escherichia coli were indistinguishable, indicating that heterologous DNA was structurally stable in the Clostridium strain. Copy numbers of 130, 70 and 10 were estimated from purification yield for pCTC1, pKNT19 and pJIR418, respectively.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 271–274.
Received 12 September 2000/ Accepted in revised form 25 November 2000 相似文献
99.
Publication of the complete diploid genome sequence of the yeast Candida albicans will accelerate research into the pathogenesis of Candida infections. Comparative genomic analysis highlights genes that may contribute to C. albicans survival and its fitness as a human commensal and pathogen. 相似文献
100.
Alistair JP Brown 《Genome biology》2010,11(5):302
A report of the symposium on Signaling and Systems Biology held during the Society for General Microbiology Spring Meeting,
29-30 March 2010, Edinburgh, UK. 相似文献