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991.
L. Mario Amzel 《Journal of bioenergetics and biomembranes》1981,13(3-4):109-121
F1-ATPases are large multimeric proteins that can be isolated from the membrane bound system that catalyzes the phosphorylation of ADP by inorganic phosphate in bacteria, plants, and mitochondria. They can be visualized in electron micrographs of the inner mitochondrial membranes where they appear as large protruding spheres 90 Å in diameter. The purified F1-ATPases have a molecular weight of 320,000 to 400,000 daltons and are composed of five non-identical subunits (, , , and ). The stoichiometry of these subunits in the complex is still unknown but compositions of the type 33 and 22222 were found to be consistent with some of the available experimental data. This review discusses the recent data and the experimental approaches utilized for the structural characterization of F1-ATPases. 相似文献
992.
Hideki Oyama Jeanne Martin Karl Sussman Gordon C. Weir Alan Permutt 《Regulatory peptides》1981,1(6):387-396
Catfish pancreatic somatostatin, which contains eight additional amino acids on the amino terminus of a tetradecapeptide with considerable homology to tetradecapeptide somatostatin (SRIF), is a naturally occurring homology of the hypothalamic peptide. The purpose of these studies was to determibe the biological activity of this somatostatin homolog. Inhibition of 125I-labelled tyr1-SRIF binding to bovine pituitart plasma membranes by catfish pancreatic somatostatin was approximately 33% that of SRIF. Pancreatic somatostatin has full biological activity measured by inhibition of growth hormone release from isolated rat pituitary cells, but 0.01–0.1% the potency of SRIF. Pancreatic somatostatin at 100 ng/ml produced a 50–60% inhibition of insulin and glucagon secretion from perfused rat pancreas, while SRIF produced comparable inhibition at 10 ng/ml. This report demonstrates that a larger molecular form and natural homolog of SRIF, isolated from fish pancreas, has the same (but reduced) biological activities in rat assay systems as somatostatin originally isolated from sheep hypothalamus. 相似文献
993.
Mario L. Rocci William J. Jusko 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1981,224(2):221-227
A high-performance liquid chromatographic technique primarily developed for use on samples from kidney perfusion studies is presented for simultaneous determination of prednisone, prednisolone and their 20β-hydroxylated metabolites. The technique employs 6β-hydroxycortisol as the internal standard. Samples are extracted with ethyl acetate, washed with sodium hydroxide and water and injected onto a silica gel column with UV detection at 254 nm. Inter- and intraday variability of the assay was determined at two concentrations of each steroid and was less than 10%. Assay steroid recovery ranged from 54.1% for prednisone to 63.2% for 20β-hydroxyprednisone. Sensitivity is 4–10 ng/ml for the steroids measured. The chromatographic conditions may be modified to permit quantitation of these steroids from plasma samples. This method may alternatively be used for quantitation of 6β-hydroxycortisol, an endogenous indicator of enzyme induction. A perfusate concentration-time profile is presented from a kidney perfusion study using prednisolone. 相似文献
994.
995.
Parasitoids of the cabbage looper,Trichoplusia ni (Hübner), the soybean looper,Pseudoplusia includens (Walker), and the tobacco budworm,Heliothis virescens (F.) were characterized in a 3.2-ha model of a north Florida (U.S.A.) cropping system (including tobacco (Nicotiana tabacum L.), soybeans (Glycine max (L.)Merr. and 18 other crops) not treated with chemical pesticides. The study was for a 2 yr-period; a minimum of three 0.0004-ha sections of row, or 0.0001-ha sections in broadcast or drilled crops were sampled weekly. In addition, sweeps with a net and some other sampling techniques were used in some crops.Litomastix truncatella (Dalman),Meteorus autographae Muesebeck, andVoria ruralis Fallen were the most important larval parasitoids recovered from cabbage loopers;Trichogramma spp. were by far the major egg parasitoid. Parasitization of eggs and larvae in crucifers (Brassica oleracea L.) ranged from 0 to 55% and 0 to 100%, respectively, and was generally highest during the spring and fall. Parasitization of cabbage looper immatures was highest in tomatoes (Lycopersicon esculentum Mill.). Parasitism by the parasitoid complex for the soybean looper larvae was high but eggs in soybeans were seldomly attacked by parasitoids. Tobacco budworm eggs were rarely parasitized in tobacco but were frequently parasitized in tomatoes and okra (Abelmoschus esculentus (L.)Medik). Parasitization of tobacco budworm larvae in tobacco was usually over 50% and was mostly byCardiochiles nigriceps Viereck; fewC. nigriceps were found from the other plants. 相似文献
996.
Norio Ogawa Tom Thompson Henry G. Friesen Joseph B. Martin Paul Brazeau 《The Biochemical journal》1977,165(2):269-277
A soluble somatostatin-binding protein was detected in the cytosol fractions of various rat, human and bovine tissues. Maximum binding occurred at pH8.0-8.5 and was Ca(2+)-dependent. The specific binding of somatostatin per 10mug of cytosol protein from 12 rat tissues ranged between 36 and 15%, and 3% for peripheral blood cells. There was also substantial binding in cytosol from human anterior pituitary and liver, and bovine anterior pituitary. The specific binding in rat and human plasma in the presence of EDTA was only 1%. Gel filtration suggested a molecular weight of approx. 80000 for the somatostatin-binding protein from several sources. Exposure of the binding protein to trypsin eliminates somatostatin-binding activity but ribonuclease and deoxyribonuclease have no effect. The binding protein is thermolabile, ethanol-precipitable, and not completely specific for somatostatin. Bound (125)I-labelled [Tyr(1)]somatostatin is not easily displaced by excess of unlabelled somatostatin. The effects of dithiothreitol and mercaptoethanol on the binding of (125)I-labelled [Tyr(1)]somatostatin to the binding protein suggests that binding involves two sequential steps, first loose binding, then disulphide linkage. Since semipurified somatostatin-binding protein causes a dose-related inhibition of the binding of (125)I-labelled [Tyr(1)]somatostatin in radioimmunoassays for somatostatin, estimates of somatostatin content of tissue extracts by radioimmunoassay in some cases may be spuriously high. It is not yet clear whether the binding protein is a true cytosol protein or an easily solubilized membrane protein. 相似文献
997.
A simple enzymic method for the synthesis of adenosine 5''-[alpha-32P]triphosphate on a preparative scale. 总被引:10,自引:9,他引:1
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A simple, rapid and inexpensive method is described for the enzymic synthesis of [alpha-32P]ATP from [32P]Pi on a preparative scale with an overall yield of 53%. The final product contained all of the detectable radioactivity (less than 99.9%) in the alpha position and has been shown to behave identically with commerically availabe [alpha-32P]ATP during the synthesis of 3':5'-cyclic AMP in the reaction catalysed by adenylate cyclase. 相似文献
998.
Summary Pi phenotypes have been determined by isoelectrofocusing in a sample of 538 healthy individuals from Southern Germany. Further subdivision of the common PiM phenotype is described. A procedure for the delineation of six common subtypes is presented. It is assumed that the six subtypes are determined by three alleles which are provisionally called PiMa, PiMb, and PiMc. Their frequencies in this sample were 0.75, 0.06, and 0.15, respectively.Supported in part by INSERM, contract No. AT-FA-58 相似文献
999.
The utility of various techniques for assessing dominance relations within captive primate groups has been repeatedly debated.
The present research compared status rankings derived from observations of spontaneous agonism with rankings based on success
in experimental competitions within two groups of captiveSaimiri. Observation of social agonism revealed stable dyadic dominance relations in both groups. Status rankings derived from the
competitive Water Dominance tests were neither temporally stable nor concordant with observational rankings. Thus the utility
of the Water Dominance test as an index of dominance among captive squirrel monkeys seems questionable. Results are discussed
in terms of ecological factors in group adaptation which lead to species-specific differences in the relationship between
social conflict and competition. 相似文献
1000.
Henry R. Black Samuel O. Thier Philip F. Felig James F. Jekel Joseph Belsky James L. Bernene Everett Cooper Vincent A. De Luca Jr. Martin H. Floch Marvin Garrell Pasquale E. Perillie Robert L. Piscatelli George F. Thornton 《The Yale journal of biology and medicine》1977,50(6):637-644
In July, 1975, the Departments of Internal Medicine at the Yale University School of Medicine and eight community hospitals in southern and western Connecticut formed the Yale Affiliated Hospital Program (YAHP) in Internal Medicine. The YAHP provides a planned and focused program of continuing education for medical staff and housestaff at the affiliated hospitals. Six formats for the over 1,000 rounds, lectures, and conferences given annually are used. The members of the YAHP also cooperate in housestaff and faculty recruiting, evaluation of quality of care and evaluation of the process of continuing medical education itself. This report summarizes the organization, goals and future plans of the YAHP. 相似文献