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981.
Hee-Kyun Lim Pham Tuan Linh Cheong-Hee Hong Kyeong-Ho Kim Jong-Seong Kang 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,755(1-2)
The enantiomeric separation of metoprolol and its metabolites in human urine was undertaken using capillary electrophoresis (CE). Resolution of the enantiomers was achieved using carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral selector. A 100-mM acetate buffer (pH 4.0) containing 5% 2-propanol and 10 mM CM-β-CD resulted in the optimum separation of the metoprolol enantiomers and its acidic metabolite in human urine. Following a single metoprolol oral administration of 100 mg racemic metoprolol tartrate, stereoselective pharmacokinetic analysis showed that urinary acidic metabolite 3 of metoprolol accounted for 62.3% of the dose with an R/S ratio of 1.23 and urinary unchanged metoprolol 1 accounted for 6.3% of the dose with an R/S ratio of 0.72. 相似文献
982.
983.
J W Kim E Y Kim H H Park J E Jung H D Kim H J Shin W K Lim 《Biochemical and biophysical research communications》2001,289(2):568-572
Tryptophan synthase alpha-subunit from Escherichia coli functionally exists as a heterotetramer of alpha(2)beta(2) with beta-subunit. While wild-type and mutant (F139W, T24M/F139W, and T24L/F139W) alpha-subunits were expressed as a monomer from recombinant plasmids in Escherichia coli, T24A/F139W, T24S/F139W, and T24K/F139W mutant alpha-subunits were abnormally expressed as soluble homodimers in addition to monomers. Monomers of dimer-forming mutant alpha-subunits retain high affinity to beta-subunit, high activity in stimulating catalytic activities of beta-subunit, and nearly intact content of secondary structure, indicating that the global structures of these monomers are identical to that of F139W alpha-subunit. However, fluorescence spectra of Trp139 and ANS binding indicate that significant perturbations occur in the mutant proteins. Interestingly, these defective properties of monomers caused by residue replacement were partially repaired by the dimer formation. As a result, it is suggested that dimers may be formed by domain or loop swapping, and that residue 24 may play important role in maintaining on-pathway of alpha-subunit folding. 相似文献
984.
Steady Flow Visualization in a Rigid Model of the Aortic Bifurcation: Application to Atherosclerosis
Hemodynamics have long been implicated in atherogenesis. The studiesreported here seek to explain the mechanisms for the formation ofatherosclerotic plaque in an aortic bifurcation. Flow studies were made ina model constructed from plexiglass to represent an aortic bifurcation. Under steady flow conditions at inflow Reynolds numbers of 80–1250,the streamline flow patterns and the boundary layer separation zones wereinvestigated in relation to the location of atherosclerotic plaques clinicallyfound at regions in the human aortic bifurcation. The streamline flowswere visualized by a slow injection of dye over the cross section of the tubeentrance and along the tube walls. The studies revealed a complex flowfield where secondary flows, induced by the centrifugal and viscous forces,cause the fluid to move towards the inner walls of the aortic bifurcation. The effect was more clearly seen with increasing Reynolds number. Boundary layer separation zones were observed to occur at the outercorners of the branching. The nature of the separation zone formed wasfound to be dependent on Reynolds number. The residence time of fluidparticles within such a separation zone was estimated by measuring thewashout time of a bolus of dye injected at strategic locations along the tubewalls. The residence time was found to decrease exponentially withincreasing Reynolds number. These observations provide strong support forthe role of flow separation in the accumulation of LDL and plateletaggregation within the aortic bifurcation. 相似文献
985.
Jeung S. Woo Byung H. Ha Tae G. Kim Yoong H. Lim Kyung H. Kim 《Biotechnology letters》2001,23(7):507-511
Horseradish peroxidase conjugation with fetuin, which expresses sialic acid-dependent binding specificity to Helicobacter pylori, was used to develop an enzyme-linked glycosorbent method. This method yielded results that were consistent with those from a hemagglutination assay using a microscope and allowed the quantitative analysis of inhibitors of sialic acid-dependent Helicobacter pylori adhesion to host cells. The results of inhibitor screening with carbohydrates, including commercially available polysaccharides and extracted from various sources, displayed not only the relative inhibition potencies among carbohydrates, but also their respective concentration-dependencies. 相似文献
986.
Jae-Hyuk Jang Seoung-Kwon Bae Dong-Jung Lim Bong-Jo Kim Jai-Yul Kong 《Biotechnology letters》2002,24(4):297-301
A newly isolated marine bacterium, identified as Zoogloea sp., produced two different polysaccharides: one was water-soluble and the other was cell-bound. Both had non-Newtonian, pseudoplastic fluid behaviour and the solutions had low activation energies. The solutions of these polysaccharides showed rheological behaviour over a wide range of pH (2–12) and temperature (20–80 °C), and compatibility with NaCl. 相似文献
987.
A new isolate of Salmonella, strain MR4, reduced Mn(IV)O2 at 2.3 mM under aerobic conditions by about 83% over 24 h. Direct contact of cells to MnO2 was not necessary as the cell-free spent medium produced a similar amount of Mn(II). Pyruvate (1.6 mM) and oxalate (0.8 mM) were identified in the culture medium and presumed to have a role in Mn(II) production in this microorganism. 相似文献
988.
S Krugmann K E Anderson S H Ridley N Risso A McGregor J Coadwell K Davidson A Eguinoa C D Ellson P Lipp M Manifava N Ktistakis G Painter J W Thuring M A Cooper Z-Y Lim A B Holmes S K Dove R H Michell A Grewal A Nazarian H Erdjument-Bromage P Tempst L R Stephens P T Hawkins 《Molecular cell》2002,9(1):95-108
We show that matrices carrying the tethered homologs of natural phosphoinositides can be used to capture and display multiple phosphoinositide binding proteins in cell and tissue extracts. We present the mass spectrometric identification of over 20 proteins isolated by this method, mostly from leukocyte extracts: they include known and novel proteins with established phosphoinositide binding domains and also known proteins with surprising and unusual phosphoinositide binding properties. One of the novel PtdIns(3,4,5)P3 binding proteins, ARAP3, has an unusual domain structure, including five predicted PH domains. We show that it is a specific PtdIns(3,4,5)P3/PtdIns(3,4)P2-stimulated Arf6 GAP both in vitro and in vivo, and both its Arf GAP and Rho GAP domains cooperate in mediating PI3K-dependent rearrangements in the cell cytoskeleton and cell shape. 相似文献
989.
Zheng Lu Jin Joon Ki Hong Dae-Jin Yun Sang Yeoi Lee Young Ju Choi Jeong Dong Bahk Roger N. Beachy Moo Je Cho Chae Oh Lim 《Journal of Plant Biology》2002,45(2):77-82
Nicotiana benthamiana plants were transformed with the movement protein (MP) gene of tobacco mosaic virus (TMV), usingAgrobacterium-mediated transformation. Plants regenerated from the transformed cells accumulated 30-kDa MP and complemented the activity of TMV
MP when infected with chimeric TMVs containing defective MR These transgenic plants displayed stunting, pale-green leaves,
and starch accumulations, indicating that TMV MP altered the carbon partitioning for leaves involved in TMV cell-to-cell movement. 相似文献
990.
Rebecca M. Rose Michael St. J. Warne Richard P. Lim 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》2002,9(3):205-211
One of the acknowledged limitations ofconventional toxicity tests is their inabilityto evaluate the impact of toxicants onsubsequent generations. Given their relativelyshort lifespan, cladocerans in the field may beexposed to toxicants for several generations.However, it is unclear what effect such anexposure regime could have on the cladoceranfitness after removal of the toxicant. Thispaper aimed to determine the offspring fitnessof juveniles produced by adult Ceriodaphnia cf. dubia exposed toresidual levels of 3,4-dichloroaniline overfour generations. Mass cultures of Ceriodaphnia cf. dubia were maintainedfor several generations in variousconcentrations of 3,4-dichoroaniline (0, 2.5,5, 10, 15 and 20 µg/L). The mass cultureswere re-established every generation using4th brood neonates <24 h old. Eachgeneration, 4th brood neonates <24 h oldwere also transferred individually intotoxicant-free water and examined until theproduction of their 3rd brood. F1offspring of mothers exposed to 15 and20 µg/L 3,4-dichloroaniline showedsignificantly (p < 0.05) reducedreproduction compared to the controls. Nosignificant (p > 0.05) changes inreproduction due to 3,4-dichloroaniline wereobserved for the F2 and F3 offspring. However,F4 offspring of mothers exposed to all3,4-dichloroaniline concentrations showedsignificantly (p < 0.05) increasedreproduction compared to the controls. Possibleexplanations for the varying influence ofmaternal 3,4-dichloroaniline exposure on thereproductive output of the offspring arediscussed. 相似文献