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排序方式: 共有335条查询结果,搜索用时 46 毫秒
1.
F. Kees M. Bucher G. Mair H. Grobecker 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,753(2):50
A high-performance liquid chromatographic method is described for the determination of opipramol in human plasma. Opipramol was extracted into tert.-butylmethyl ether, separated on a cyanopropyl silica column and detected at 254 nm. Imipramine was used as internal standard. The limit of quantitation was 250 pg/ml using 1.5 ml plasma. Precision was better than 9%, inaccuracy less than 8%. The assay is more sensitive than previously published methods, and it has been applied to the analysis of plasma samples from a pharmacokinetic study. 相似文献
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Sorichter Stephan; Mair Johannes; Koller Arnold; Gebert Walter; Rama Daniel; Calzolari Charles; Artner-Dworzak Erika; Puschendorf Bernd 《Journal of applied physiology》1997,83(4):1076-1082
Sorichter, Stephan, Johannes Mair, Arnold Koller, WalterGebert, Daniel Rama, Charles Calzolari, Erika Artner-Dworzak, and BerndPuschendorf. Skeletal troponin I as a marker of exercise-inducedmuscle damage. J. Appl. Physiol.83(4): 1076-1082, 1997.The utility of skeletal troponin I (sTnI)as a plasma marker of skeletal muscle damage after exercise wascompared against creatine kinase (CK), myoglobin (Mb), and myosin heavychain (MHC) fragments. These markers were serially measured in normalphysical education teacher trainees after four different exerciseregimens: 20 min of level or downhill (16% decline) running(intensity: 70% maximal O2uptake), high-force eccentric contractions (70 repetitions), orhigh-force isokinetic concentric contractions of the quadriceps group(40 repetitions). Eccentrically biased exercise (downhill running andeccentric contractions) promoted greater increases in all parameters.The highest plasma concentration were found after downhill running{median peaks: 309 U/l CK concentration ([CK])}, 466 µg/l Mb concentration([Mb]), 1,021 µU/l MHC concentration ([MHC]),and 27.3 µg/l sTnI concentration ([sTnI]). Level running produced a moderate response (median peaks: 178 U/l [CK],98 µg/l [Mb], 501 µU/l [MHC], and 6.6 µg/l [sTnI]), whereas the concentric contraction protocoldid not elicit significant changes in any of the markers assayed. sTnIincreased and peaked in parallel to CK and stayed elevated (>2.2µg/l) for at least 1-2 days after exercise. In contrast to MHC,sTnI is an initial, specific marker of exercise-induced muscle injury,which may be partly explained by their different intracellularcompartmentation with essentially no (MHC <0.1%) or a small solublepool (sTnI: median 3.4%). 相似文献
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A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
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Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu. 相似文献
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U Quast J Engel E Steffen G Mair H Tschesche H Jering 《European journal of biochemistry》1975,52(3):505-510
Equilibrium measurements of the binding of reactive-site-cleaved (modified) bovine trypsin-kallikrein inhibitor (Kunitz) to alpha-chymotrypsin and beta-trypsin show a stoichiometric 1:1 association with high binding constants. At least in the case of chymotrypsin much evidence is presented that the reaction with modified inhibitor leads to the same complex as the reaction with virgin inhibitor does. The association rate constant of modified inhibitor with chymotrypsin at pH 7, 22.5 degrees C is 15.8 M-1 S-1. This is about 2 x 10(4) times slower than the binding of virgin inhibitor to that enzyme. In the analogous reaction of modified inhibitor with beta-trypsin, however, the association rate constant (1.2 x 10(4) M-1 s-1 at pH 6.9, 22.5 degrees C) is of about the same order of magnitude as it is in the reaction of virgin inhibitor and trypsin. These and analogous phenomena observed in the reactions of virgin and modified soybean trypsin inhibitor (Kunitz) with alpha-chymotrypsin and beta-trypsin suggest that the specificity of both inhibitors to trypsin is strongly reflected in the association rate constants of the modified forms. The dissociation rate constants of the complexes of trypsin-kallikrein inhibitor with chymotrypsin or with trypsin towards the modified inhibitor are estimated to be unmeasurably slow (half-life times of 45 or 1.5 x 10(4) years, respectively). 相似文献
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Dietary restriction (DR) extends life span in diverse organisms, including mammals, and common mechanisms may be at work. DR is often known as calorie restriction, because it has been suggested that reduction of calories, rather than of particular nutrients in the diet, mediates extension of life span in rodents. We here demonstrate that extension of life span by DR in Drosophila is not attributable to the reduction in calorie intake. Reduction of either dietary yeast or sugar can reduce mortality and extend life span, but by an amount that is unrelated to the calorie content of the food, and with yeast having a much greater effect per calorie than does sugar. Calorie intake is therefore not the key factor in the reduction of mortality rate by DR in this species. 相似文献