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L Hertz J S Richardson S Mukerji 《Canadian journal of physiology and pharmacology》1980,58(12):1515-1519
Doxepin binds to intact astrocytes in primary cultures. The binding is competitively displaceable by excess cold doxepin and it is pronounced (Bmax = 27 nmol/mg protein) but the affinity is rather low (KD = 30 microM). The binding is inhibited by other antidepressants (amitriptyline, desipramine, tranylcypromine, iprindole) and propranolol but not by isoproterenol. Nevertheless, doxepin counteracts effectively the increase in the production of cyclic AMP evoked by isoproterenol. 相似文献
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Circularly polarized emission (CPE) and total emission (TE) spectra are reported for Eu3+ and Tb3+ complexes of L-aspartic acid (L-asp), L-serine (L-ser), L-threonine (L-thr) and L-histidine (L-his) in D2O solution under various pH conditions. Variations in TE and CPE intensities and in CPE splittings and sign patterns as functions of solution pH are correlated with lanthanide ion/ligand binding characteristics and with structural changes in the coordination environment of the metal ion. In the Eu3+/amino acid systems, the emission bands associated with the 5D0 leads to 7F1 and 7F2 Eu3+ transitions are monitored, and in the Tb3+/amino acid systems the 5D4 leads to 7F5 Tb3+ emission is examined. 相似文献
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The ultrastructure of human spermatozoa at various stages of the freezing and thawing process was studied. In addition to conventional fixations, a freeze-substitution method was used to examine spermatozoa before they were thawed. Dilution in a glycerol-egg yolk-citrate medium caused slight swelling of the acrosome. During slow freezing, when large ice crystals grow in the diluent, the sperm plasmalemma became tighter, the mitochondria had more angular profiles and there was a reduction in electron density of the acrosomal contents. After thawing, the apical segment of the acrosome usually became swollen and the mitochondria appeared rounded. We deduce that these ultrastructural changes occur either during or after the thawing procedure. 相似文献
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Ronald L. Gambardella Keith E. Richardson 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,499(1):156-168
The metabolic pathway by which L-[14C1]phenylalanine, L-[14C1]tyrosine, L-[14C1]tryptophan, and L-[14C1]ascorbic acid are converted to [14C]oxalate have been investigated in the male rate. Only [14C]oxalate was detected in the urine of rats injected with L-[14C1]ascorbic acid, but [14C]-labeled oxalate, glycolate, glyoxylate, glycolaldehyde, glycine, and serine were recovered from the [14C1]-labeled aromatic amino acids. DL-Phenyllactate, an inhibitor of glycolic acid oxidase and glycolic acid dehydrogenase, reduced the amount of [14C]oxalate recovered in the urine of rats given the [14C1]-labeled aromatic amino acids, but increased the amount of [14C]glycolate formed from L-[14C1]-phenylalanine and L-[14C1]tyrosine and the amount of [14C]glycolate produced from [14C1]tryptophan. Based on the [14C]labeled intermediates identified and the relative distribution of the radioactivity, it is postulated that phenylalanine and tyrosine are converted to oxalate via glycolate which is oxidized directly to oxalate by glycolic acid dehydrogenase. Tryptophan is metabolized via glyxylate which is oxidized directly to oxalate by glycolic acid oxidase. Neither glycolate, glyoxylate, glycolic acid oxidase or glycolic acid dehydrogenase are involved in the formation of oxalate from ascorbic acid. 相似文献