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51.
Inhibition of dihydropteridine reductase by dopamine 总被引:1,自引:1,他引:0
Dihydropteridine reductase has been purified 900-fold from rat liver. Dopamine inhibited the enzyme up to 50% at a concentration of 0.11mm. In the presence of dopamine the enzyme gave non-hyperbolic v-against-[S] plots. This enzyme may have a role in control of dopamine biosynthesis. 相似文献
52.
A unicellular chlorococcalean alga, Pseudotetraëdron polymorphum MacEntee, Bold & Archibald is renamed Chlorotetratëdron polymorphum (MacEntee, Bold & Archibald) MacEntee, Bold & Archibald became the former generic designation has been preempted by a xanthophycean alga. 相似文献
53.
Daniel V. Santi Ursula Edman Svetlana Minkin Patricia J. Greene 《Protein expression and purification》1991,2(5-6)
Gatalytically active Pneumocystis carinii thymidylate synthase is expressed to the extent of about 4% of the soluble protein in Escherichia coli χ2913 harboring plasmid pUETS-1.8 (U. Edman, J. C. Edman, B. Lundgren, and D. V. Santi, Proc. Natl. Acad. Sci. USA 86, 6503–6507, 1989). Ion-exchange, affinity, hydrophobic, and reactive dye agarose chromatography steps were explored to devise a large-scale purification protocol for P. carinii thymidylate synthase. Sequential DE52, Q-Sepharose, phenyl-Sepharose, and Cibacron Blue F3GA chromatography yielded enzyme that was homogeneous by SDS-PAGE in a yield of over 50%. The sequence of the first 10 amino acid residues of the purified protein was in accord with that predicted from the DNA sequence. Isoelectric focusing gave a pI of 6.2. Kinetic analysis of the purified enzyme revealed that the the Km values were 4.7 ± 1.3 μM for dUMP and 15.7 ± 4.3 μM for 5,10-methylenetetrahydrofolate, similar to those of many other thymidylate synthases; the κcat of the most active preparation was 0.8 s−1. The enzyme is stable for at least 2 months when stored at −80°C in the presence of 40% glycerol, Tris-HCl, and thiol. 相似文献
54.
Angele McGrady Ph.D. M.Ed. Patricia Ann Nadsady Cathleen Schumann-Brzezinski 《Applied psychophysiology and biofeedback》1991,16(4):399-411
The usefulness of biofeedback-assisted relaxation as an adjunct or substitute for pharmacotherapy in essential hypertension can be enhanced if the effects are shown to persist after formal treatment has ended. Patients with essential hypertension successfully treated with biofeedback-assisted relaxation were recalled for follow-up yearly after the termination of treatment. Twenty-six of 40 patients met the BP criterion for success. At one-, two-, and three-year follow-up, 31%, 38%, and 27% of the successful completers continued to meet the criterion for success. The pretreatment-posttreatment decreases in BP were accompanied by decreases in forehead muscle tension and urinary cortisol. Forehead muscle tension, urinary cortisol, and anxiety levels were significantly lower than pretreatment one year after the end of treatment. Self-report data were used to assess continued relaxation practice. No relationship was found between practice and any other dependent measure. It appears that some patients trained in biofeedback-assisted relaxation can maintain lowered blood pressure, muscle tension, anxiety, and cortisol levels over the long term; however, the role of relaxation practice in maintaining these lowered levels remains unclear. 相似文献
55.
56.
Patricia Maurer Corinne Royer Bernard Mauchamp Patrick Porcheron Danile Debieu Guy Riba 《Archives of insect biochemistry and physiology》1991,16(1):1-9
The major ecdysteroids in large worker pupae of the leaf-cutting ant Acromyrmex octospinosus were characterized at the peak ecdysteroid concentration by using high-performance liquid chromatography, enzyme immunoassay, and mass spectrometry. In decreasing amounts, they were determined to be makisterone A, an unidentified C28 ecdysteroid bearing a molecular weight of 494, 20-hydroxyecdysone (ratio of 1 to 6 as compared to makisterone A), and putative but negligible ecdysone. The presence of both C28 and C27 ecdysteroids is discussed in relation to the content of 4-desmethylsterols determined by gas chromatography and mass spectrometry to be ergosta-5,7,24 (28)-trien-3β-ol, ergosterol, ergosta-5,7-dien-3β-ol and ergosta-7,24(28)-dien-3β-ol for the main sterols, and with a small amount of cholesterol. 相似文献
57.
Patricia Arevalo-Durup 《BioControl》1992,37(2):239-247
Les interactions h?te-parasito?de ont été abordées dans le cas du systèmeTrichomalopsis peregrina G. (Pteromalidae) et son h?te grégaireEuproctis chrysorrhoea L. (Lymantriidae), au cours de la phase diapausante des chenilles dans les nids d'hiver tissés par ce ravageur. Un échantillon de 1 432 nids
d'hiver a été récolté dans 8 peuplements de chênes dans la région toulousaine durant l'hiver 1988. Le volume du nid a été
utilisé comme estimateur du nombre de chenillesh?tes dans les nids et la réponse du parasito?de a été comparée à celle prévue
par la théorie de la stratégie optimale de recherche. Les principaux résultats sont les suivants:
Host-parasitoid interactions are reviewed in the case ofTrichomalopsis peregrina G. (Pteromalidae) and its aggregated host,Euproctis chrysorrhoea (Lymantriidae) during the arrest of development of the caterpillars in the winter nest spun by this forest pest. A sample of 1,432 winter
nests in 8 oak groves near Toulouse, Haute-Garonne, France were collected during the winter 1988. The volume of the winter
nests has been used to estimate the number of larvae in nests. The response of the parasitoid has been compared with the optimal
searching theory for parasitoids. The main results are:
(i) Parasitoids present an aggregative response; to a higher density of host larvae corresponds a higher number of apparent
attacks; (ii) in contrast with that theory, the apparent rate of parasitism is inversely density dependent with respect to
caterpillar density in the nest; (iii) these results suggest that the access of the parasito?d to the caterpillars is limited
to the proximity of the nest surface. 相似文献
(i) | les parasito?des présentent une réponse agrégative typique, les plus fortes densités d'h?tes correspondant au plus grand nombre de parasito?des sortant des nids; |
(ii) | contrairement à la théorie, les taux de parasitisme apparent varient en sens inverse des effectifs de chenilles par nid; |
(iii) | ces résultats suggèrent l'existence d'une accessibilité limitée des chenilles, l'activité parasitaire s'exer?ant sur les chenilles proches de la surface du nid. |
58.
Johannes D. Veldhuis Patricia Klase Laurence M. Demers 《Prostaglandins & other lipid mediators》1982,23(3):319-327
Granulosa cells isolated from mature Graafian follicles of swine produced significant quantities of immunoreactive 6-keto-PGF1α under chemically defined conditions in vitro. Luteinizing hormone elicited a dose-dependent stimulation of 6-keto-PGF1α accumulation, but follicle stimulating hormone, prolactin, L-epinephrine, estradiol-17B, or PGE2 were devoid of effect. The time-dependent in vitro production of 6-keto-PGF1α by ovarian cells was susceptible to inhibition by indomethacin, U-51506, cycloheximide, and actinomycin D. These observations implicate granulosa cells in the specific and hormonally regulated production of prostacyclin. 相似文献
59.
Bile acid amides and oxazolines were synthesized by a sequence of steps involving the reaction of the free bile acid with formic acid to yield the formyloxy derivative, preparation of the formyloxy acid chloride, condensation of the acid chloride with 2-amino-2-methyl-1-propanol to give the amide and, finally, cyclization of the amide with thionyl chloride to give the oxazoline. The oxazolines were characterized by physical constants, thin layer and gas-liquid chromatography and identified by elemental analysis and gas-liquid chromatography-mass spectrometry. Some of the bile acid oxazoline derivatives alter the activity of bacterial 7-dehydroxylases , and inhibit the growth of certain anaerobic bacteria in pure culture. 相似文献
60.
John S. Hothersall Salmata Zubairu Patricia McLean A. Leslie Greenbaum 《Journal of neurochemistry》1981,37(6):1484-1496
The effect of 6-aminonicotinamide (6AN) treatment on the activities of alternative pathways of glucose metabolism in 20-day-old rat brain was evaluated by measurements of yields of 14CO2 from glucose labeled with 14C on carbons 1, 2, 3 + 4, or 6 and uniformly labeled glucose, and from the incorporation of 14C from specifically labeled glucose into lipids by brain slices from cerebral hemispheres and cerebellum. At the highest dose of 6AN used (35 mg/kg body weight) there was a significant decrease in the 14CO2 yields via the pentose phosphate pathway, the glycolytic route, tricarboxylic acid (TCA) cycle, and via the glutamate-gamma-aminobutyric acid pathway. Giving a graded series of doses (20-35 mg 6AN/kg body weight) revealed a hierarchy of responses in which the pentose phosphate pathway, lactate, glyceride-glycerol, and fatty acid formation were most sensitive, followed, in sequence, by the pyruvate dehydrogenase reaction, the glutamate-gamma-aminobutyrate route and, finally, the TCA cycle. The nature of the blocks in the various pathways was examined by the use of metabolite profiles. 相似文献