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991.
992.
Robert E. Bowden James H. Ware David L. DeMets Harry R. Keiser 《Prostaglandins & other lipid mediators》1977,14(1):151-161
The excretion of urinary immunoreactive prostaglandin E (iPGE), sodium, potassium, creatinine and volume was studied in 4 hr collections in normal women at normal activity. iPGE exhibited a circadian rhythm with an amplitude of 29% and peak excretion at 4:55 P.M. There were also significant circadian rhythms for sodium, potassium, creatinine, and volume, all peaking in late afternoon. There were no significant changes either in the total excretion or in the circadian rhythms of iPGE, potassium, or creatinine excretion when the subjects remained in bed for an entire day while the circadian rhythms of sodium and volume were significantly modified in amplitude and phase, respectively. Urinary aldosterone excretion decreased significantly when the subjects were at bed rest. iPGE excretion increased 33% when subjects were first recumbent and then erect for consecutive 4 hr periods on the same day (but when subjects were erect 1 day for a 4 hr period, iPGE excretion was lower by 32% than for the same 4 hr period the preceding day when they were recumbent). These data indicate that: 1) the sympathetic nervous system and renin-angiotensin-aldosterone system do not affect the circadian rhythm of urinary iPGE, and 2) short-term experiments of prostaglandin E excretion must be designed to avoid misleading results due to the circadian rhythm. 相似文献
993.
994.
995.
James W. Carpenter 《Zoo biology》1983,2(3):165-178
This keynote address was presented at the Conference on the Conservation of Endangered Species in Zoological Parks and Aquariums on April 18, 1982 at the National Aquarium in Baltimore. It outlines 1) future trends in the world's environment, resources, and population; 2) factors affecting species decline; 3) reasons for preserving life forms; and 4) techniques, with emphasis on captive propagation, used to assist in species recovery. 相似文献
996.
James W. Wallace Kenneth R. Markham David E. Giannasi John T. Mickel Don L. Yopp Luis D. Gomez J. Dan Pittillo Robert Soeder 《American journal of botany》1982,69(3):356-362
A survey for 1,3,6,7-tetrahydroxy-C-glycosylxanthones of representative species within the primitive vascular plants, emphasizing the leptosporangiate ferns, has indicated a limited distribution of these compounds within three leptosporangiate families: Hymenophyllaceae, Aspleniaceae and Marsileaceae. In the Hymenophyllaceae the distribution of these compounds appears to be a useful criterion for segregating species of Mecodium from other species of Hymenophyllum (sensu lato) and suggests that the tubulate vs. the valvate indusial condition may not be an ideal character for separating all species of Hymenophyllum (s.l.) from those of Trichomanes (s.l.). These compounds appear useful for delimiting several species of Elaphoglossum section Pachyglossa and support a relationship among the Aspleniaceae, Athyriaceae, and Elaphoglossaceae. Their presence in Marsilea also raises questions as to the origin of this group of plants. 相似文献
997.
Kinetics of Formate Metabolism in Methanobacterium formicicum and Methanospirillum hungatei 总被引:7,自引:6,他引:1 下载免费PDF全文
The kinetics of formate metabolism in Methanobacterium formicicum and Methanospirillum hungatei were studied with log-phase formate-grown cultures. The progress of formate degradation was followed by the formyltetrahydrofolate synthetase assay for formate and fitted to the integrated form of the Michaelis-Menten equation. The Km and Vmax values for Methanobacterium formicicum were 0.58 mM formate and 0.037 mol of formate h−1 g−1 (dry weight), respectively. The lowest concentration of formate metabolized by Methanobacterium formicicum was 26 μM. The Km and Vmax values for Methanospirillum hungatei were 0.22 mM and 0.044 mol of formate h−1 g−1 (dry weight), respectively. The lowest concentration of formate metabolized by Methanospirillum hungatei was 15 μM. The apparent Km for formate by formate dehydrogenase in cell-free extracts of Methanospirillum hungatei was 0.11 mM. The Km for H2 uptake by cultures of Methanobacterium formicicum was 6 μM dissolved H2. Formate and H2 were equivalent electron donors for methanogenesis when both substrates were above saturation; however, H2 uptake was severely depressed when formate was above saturation and the dissolved H2 was below 6 μM. Formate-grown cultures of Methanobacterium formicicum that were substrate limited for 57 h showed an immediate increase in growth and methanogenesis when formate was added to above saturation. 相似文献
998.
Polygena T. Tuazon James T. Stull Jolinda A. Traugh 《Biochemical and biophysical research communications》1982,108(2):910-917
Protease activated kinase I from rabbit reticulocytes has been shown to phosphorylate the P-light chain of myosin light chains isolated from rabbit skeletal muscle. The enzyme is not activated by Ca2+ and calmodulin or phospholipids. Protease activated kinase I is not inhibited by trifluoperazine at concentrations up to 200 μM or by the antibody to the Ca2+, calmodulin-dependent myosin light chain kinase from rabbit skeletal muscle. Two-dimensional peptide mapping of chymotryptic digests of myosin P-light chain show the site phosphorylated by the protease activated kinase is different from that phosphorylated by the Ca2+, calmodulin-dependent myosin light chain kinase. 相似文献
999.
James R. Wilson Milton M. Weiser Boris Albini Jay R. Schenck Harry G. Rittenhouse A.A. Hirata Eric G. Berger 《Biochemical and biophysical research communications》1982,105(2):737-744
Preparations of human malignant effusion galactosyltransferase activity purified according to previously published techniques using enzyme-specific affinity chromatography consistently produced antibodies directed toward immunoglobulins with no detectable antigalactosyltransferase. Double immunodiffusion analysis of the antigen showed the presence of both IgG and IgA. Affinity chromatography with anti-human IgG-Sepharose and anti-human serum-Sepharose resulted in a 48,000-fold purification of galactosyltransferase activity with no detectable IgG by radioimmunoassay. Immunization of rabbits with this preparation produced antibodies directed against galactosyltransferase activity and minimal anti-Ig. The persistence of immunoglobulins during the purification of soluble galactosyltransferase activity through two enzyme-specific affinity chromatographic steps suggests an association of immunoglobulins with galactosyltransferase activity. 相似文献
1000.
James R. White Heather N. Yeowell 《Biochemical and biophysical research communications》1982,106(2):407-411
The lethal action of streptonigrin on strains of is greatly enhanced by citrate (10?2 M). Desferrioxamine (2×10?4 M), when added with streptonigrin and citrate, eliminates the citrate enhancement. These observations point to a role for iron in the bactericidal mechanism of streptonigrin. Extracellular citrate is known to promote the acquisition of iron by by delivering it as a ferric citrate complex to a specific transport apparatus on the cell envelope. Therefore, it may promote action of streptonigrin by increasing the intracellular concentration of available iron. Desferrioxamine, which forms a much stronger complex with ferric ion than does citrate, would be expected to suppress the ferric citrate effect, and this was observed. 相似文献