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21.
David L. Musso Nariman B. Mehta Francis E. Soroko Robert M. Ferris Elizabeth B. Hollingsworth Bernard T. Kenney 《Chirality》1993,5(7):495-500
The synthesis of the enantiomers of bupropion, (rac)-2-tert-butylamino-3′-chloropropiophenone 1 (Wellbutrin®) is described. The enantiomers were compared with the racemate in both the tetrabenazine-induced sedation model and the inhibition of uptake of biogenic amine assay. No significant differences were found in their potencies to reverse tetrabenazine-induced sedation in mice or in their IC50 values as inhibitors of biogenic amine uptake into nerve endings obtained from mouse brain. © 1993 Wiley-Liss, Inc. 相似文献
22.
The dependence of PC1 and ATP1 dephosphorylation on the number of isometric twitches in the iodoacetate-nitrogen-poisoned muscle has been examined. There is no net dephosphorylation of adenosinetriphosphate. PC dephosphorylation varies linearly with the number of twitches and produces equivalent amounts of C1 and P1i.1 Iodoacetate concentrations which block the enzyme, creatine phosphokinase, render the muscle non-contractile. A value of 0.286 µmole/gm. for the amount of PC split per twitch is obtained which gives a value of -9.62 kcal./mole for the "physiological" heat of hydrolysis of PC in agreement with expectations based on thermochemical data. In a single maximal isometric twitch it is estimated that 2 to 3 PC molecules are dephosphorylated per myosin molecule, or 1 per actin molecule. The results support the view that under the conditions of these experiments PC dephosphorylation is the net energy yielding reaction. The in vivo stoichiometry of the mechano-chemistry of contraction revealed by these studies on the one hand, and the known stoichiometry of actin polymerization and its coupling to the creatine phosphokinase system on the other are strikingly similar and strongly suggest that the reversible polymerization of actin is involved in a major way in the contraction-relaxation-recovery cycle of muscle. 相似文献
23.
Shau-Ting Chiu Lori H. Anton Frank W. Ewers Raymond Hammerschmidt Kurt S. Pregitzer 《American journal of botany》1992,79(2):149-154
Fertilized stands of Pseudotsuga menziesii were found to have glaucous needles. We investigated the morphological and quantitative characteristics of the epicuticular waxes of needles of fertilized and control trees. Glaucousness was caused by ornate tubular epicuticular wax. Dipping needles in chloroform, which dissolves waxes, eliminated the glaucous appearance. Based on cryostage scanning electron microscopic observations, the epicuticular waxes in the nonstomatal region were much more ornate on the needles of the fertilized trees (experimental needles) than in unfertilized trees (control needles). The stomatal region in both experimental and control needles showed similarly ornate waxes. Quantities of waxes were similar in experimental and control needles. The glaucousness was not the result of greater quantities of wax; rather, fertilization altered wax morphology in the nonstomatal regions. 相似文献
24.
We have established a high-resolution genetic map of the region surrounding the Fused locus as a first step towards the molecular identification and analysis of this gene. The candidate region has been covered to a large extent by YAC and P1 contigs, and has been partly characterized by pulsed-field gel analysis. 相似文献
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A method is described for the estimation of adenosine 3′,5′-monophosphate (3′,5′-cyclic AMP) in rat brain by high-pressure liquid chromatography (HPLC). The nucleotide is purified initially by being passed through two columns, alumina and AG-1X2. The peak in HPLC was identified by a number of methods. Optimum parameters for HPLC were obtained by using 1 mm KH2PO4 buffer, pH 4.8, at a flow rate of 57 ml/hr at room temperature. Using this technique the concentration of 3′,5′-cyclic AMP in rat brain was found to be 2.53 ± 0.40 nmol/g (mean ± SD, n = 5). 相似文献
27.
Summary The sexual development of 14 girls with non-mosaic monocentric 46,X,iXq karyotype was studied. Seven out of eight girls were found to have immature secondary sexual characteristics and amenorrhoea, a finding greatly contrasting with that in Triplo-X girls. The relative ineffectiveness of the isochromosome Xq in maintaining fertility may be due to the absence of one short arm, which probably also carries a gonadal determinant. Alternatively, the presence of two inactivation sites on one isochromosome may render the gonadal determinants inactive at an important stage in gonadal development. 相似文献
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Chromosomal DNA replication was investigated in root meristem cells of Secale cereale L. cv. Petkus Spring using DNA fibre auto-radiography. At 23 ° the mean rate of replication, per single replicon fork, was 12.1 m/h. Replicon size was between 20–25 m. These results are compared with corresponding measurements for other angiosperm species. 相似文献
30.
Mutants were selected that are incapable of differentiating microcysts, a resting stage formed in response to high osmotic conditions. In the selection procedure amebae that failed to encyst were removed by flotation in 46% Percoll. Genetic crosses among 15 mutant strains were made by means of the macrocyst sexual cycle. Eleven of the strains mapped to three loci. Mutations at two of these loci (cysA and cysB) produced no observable alteration in the aggregation-fruiting pathway, although one set of strains altered at the cysA locus carried defects at a second unlinked site which blocked aggregation. The single strain that defined the third locus (cysC) is aggregateless. These results confirm the conclusion that there are several genes whose function is essential to microcyst development and is exclusive to this pathway. It remains uncertain whether there are other genes whose action is crucial to both encystment and to aggregation/fruiting. 相似文献