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排序方式: 共有469条查询结果,搜索用时 15 毫秒
391.
392.
393.
J. Laporte A. Hallee K. Maghni C. Robidoux P. Borgeat P. Sirois 《Prostaglandins & other lipid mediators》1991,41(3)
A method for the isolation of non-ciliated bronchiolar epithelial (Clara) cells from the guinea pig is described. Following digestion of the lung tissue with Type XXIV protease, the isolated lung cells showed a viability greater than 90 % and contained 3 % of Clara cells. Several cell populations were then separated on the basis of size using 2 centrifugal elutriations. The macrophages and endothelial cells were removed from the Clara cells enriched fractions by differential adherence on Petri dishes. The Clara cell-rich suspension was then further purified by centrifugation on Percoll non-continuous density gradients consisting of 48-52-55 % Percoll solution. The lower interface and the pellet of the non-continuous gradient consisted of approximately 80 % Clara cells. Identification of isolated Clara cells was confirmed by light microscopic observations after nitroblue tetrazolium staining and by ultrastructural characteristic features as observed by electron microscopy. The metabolism of arachidonic acid into prostaglandins and TxB2 by purified Clara cells was examined by enzyme immunoassay (EIA) and leukotriene formation was investigated by reverse phase high performance liquid chromatography (RP-HPLC). Enriched guinea pig Clara cells incubated with arachidonic acid released TxB2, PGE2 and 6-keto PGF1α, but did not produce leukotrienes. These cells could however transform exogenous leukotriene A4 into leukotriene B4. These results suggest that guinea pig Clara cells possess the enzymes of the cyclooxygenase pathway required for TxB2, PGE2 and 6-keto-PGF1α synthesis. Clara cells do not possess the 5-lipoxygenase enzyme but show some leukotriene A4 hydrolase activity since they can produce leukotriene B4 upon incubation with leukotriene A4. 相似文献
394.
Jacek Blazewicz Horst A. Eiselt Gerd Finke Gilbert Laporte Jan Weglarz 《Flexible Services and Manufacturing Journal》1991,4(1):5-16
Due to their increasing applicability in modern industry, flexible manufacturing systems (FMSs), their design, and their control have been studied extensively in the recent literature. One of the most important issues that has arisen in this context is the FMS scheduling problem. This article is concerned with a new model of an FMS system, motivated by the practical application that takes into account both machine and vehicle scheduling. For the case of a given machine schedule, a simple polynomial-time algorithm is presented that checks the feasibility of a vehicle schedule and constructs it whenever one exists. Then a dynamic programming approach to construct optimal machine and vehicle schedules is proposed. This technique results in a pseudopolynomialtime algorithm for a fixed number of machines. 相似文献
395.
T Koscielniak M Ponchant A M Laporte Y Guminski D Verge M Hamon H Gozlan 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1990,311(6):231-237
This paper describes the synthesis and the pharmacological characteristics of the first radioiodinated ligand of central 5-HT3 receptors: [125I]iodo-zacopride. Specific sites having a high affinity (Kd = 4.3 nM) for [125I]iodo-zacopride have been found in membranes from the rat entorhinal cortex. In addition, a highly significant correlation (r = 0.995) existed between the Ki of several 5-HT-related drugs for displacing both [125I]iodo-zacopride from its specific binding sites, and [3H]zacopride from 5-HT3 receptors. Finally, [125I]iodo-zacopride was successfully used for the autoradiographic mapping of 5-HT3 receptors in the rat central nervous system. 相似文献
396.
In etiolated pea and maize leaves illuminated after incubation at 38 degreesC, a new dark reaction was shown manifested in the bathochromic shift of spectral bands and accompanied by esterification of the product of protochlorophyllide photochemical reduction--Chld 684/676: Chld 684/676 --> Chl 688/680. After completion of the reaction a rapid (20-30 sec) quenching of the fluorescence of the reaction product (Chl 688/680) was observed. The reaction Chld 684/676 --> Chl 688/680 is inhibited under anaerobic conditions and in the presence of cyanide; the reaction accompanied by Chl 688/680 fluorescence quenching is not observed in pea mutants with impaired function of photosystem II reaction centers. The spectral properties of the formed Chl form with the absorption maximum at 680 nm, fluorescence quenching, and simultaneous synthesis of pheophytin suggest that the reaction is connected with the chlorophyll of photosystem II reaction center--P-680. 相似文献
397.
Couchy I; Minic Z; Laporte J; Brown S; Satiat-Jeunemaitre B 《Journal of experimental botany》1998,49(327):1647-1659
A few small GTP-binding proteins of the Ras superfamily have been
identified in plants, including members of the Rho family: the proteins
belonging to this group are known in mammalian and yeast cells to be
involved in the control of polarity, cell morphogenesis and movement by
regulating cytoskeleton organization. An investigation into where some
Rho-like proteins are located in plant cells was made. The antibodies used,
anti-Cdc42Hs and anti-Rac 1, were raised against conserved characteristic
sequences of Cdc42Hs and Rac1 mammalian proteins respectively. In fixed
cells, Cdc42Hs antibody recognized epitopes generally co-localized with
microtubules which may be implicated in the establishment of cell polarity,
whereas the proteins recognized by Rac1 antibody seemed to be associated
with organelle membranes. The same anti-bodies were used in Western blots
of proteins from tobacco BY-2 and lucerne A2 suspension cells: Cdc42Hs
antibody recognized three bands whereas Rac1 antibody revealed only one
band of 18 kDa Mr. A [35S]GTP overlay revealed
four bands of the same Mr as those recognized in
Western blots by Cdc42Hs and Rac1 antibodies.Key words: Rho G-proteins,
Cdc42, Rac1, Immunofluorescence, plant cells.
相似文献
398.
Serge Brodeur Jean-Pierre L. Savard Michel Robert Pierre Laporte Pierre Lamothe Rodger D. Titman Stéphane Marchand Scott Gilliland Guy Fitzgerald 《Journal of avian biology》2002,33(2):127-137
During May 1996 and April 1997, eight harlequin duck males were captured and fitted with satellite transmitters while migrating along the shores of Forillon National Park, Québec, Canada. Another 17 males were equipped with satellite transmitters in river systems of eastern Hudson Bay, Ungava Bay and northern Labrador in June 1997 and 1998. Our objectives were to determine relationships between breeding, moulting and wintering areas, and to determine whether distinct population segments existed among harlequin ducks in eastern North America. All birds tracked from Forillon migrated to Labrador. Moulting areas were identified for six birds. Forillon males were followed to the eastern North American major wintering site in Maine. Males captured in northern Québec and Labrador migrated to moult and winter in south-western Greenland. Our data suggest the presence of two demographically distinct population segments in eastern North America, perhaps originating from the Pleistocene glacial refuge in western Greenland and south of the Laurentide ice sheet in eastern Canada or United States. 相似文献
399.
The ratio of loculus volume to the volume of the entire anther began to increase from the microspore mother cell stage and
reached 32.3% at anthesis. The content of the loculus was examined in Lilium during pollen development and two waves could be distinguished. From the premeiotic stage until the vacuolated microspore
stage, the loculus consisted of neutral polysaccharides, pectins and proteins. These substances originated from tapetal activity
from the premeiotic stage until the young microspore stage. Dictyosomes and rough endoplasmic reticulum seemed to be involved
in tapetal secretion, although, in some mitochondria, vesicles progressively developed as early as premeiosis and increased
until the young microspore stage, which could reveal their involvement in the secretion process. At this stage, numerous cytoplasmic
vesticles containing material similar to the locular material fused with the plasma membrane of the tapetum so that vesicle
content was in contact with the loculus. It seems that tapetal and callose wall degradation at the late tetrad stage may also
have contributed to the production of material in the loculus. From pollen mitosis to anthesis, the anther loculus contained
mainly the pollenkitt which was synthesized in the tapetum between the young microspore stage and the vacuolated microspore
stage. At the young microspore stage, proplastids divided and developed into elaioplasts and smooth endoplasmic reticulum
(SER) increased dramatically. Pollenkitt had a double origin: some droplets were extruded directly from the plastid stroma
through the plastid envelopes; the others were unsaturated lipid globules, which presumably derived from the interaction between
SER saccules and plastids.
Received: 2 September 1997 / Revision accepted: 12 March 1998 相似文献
400.
A role for MAP kinase in differentiated smooth muscle contraction evoked by alpha -adrenoceptor stimulation 总被引:3,自引:0,他引:3
Dessy Chantal; Kim Inkyeom; Sougnez Carrie L.; Laporte Regent; Morgan Kathleen G. 《American journal of physiology. Cell physiology》1998,275(4):C1081
The purpose of this study was to investigate the potential roleof mitogen-activated protein (MAP) kinase in smooth muscle contractionby monitoring MAP kinase activation, caldesmon phosphorylation, andcontractile force during agonist stimulation. Isometric tension inresponse to KCl and phenylephrine (PE) was measured from strips offerret aorta. MAP kinase activation was monitored by Western blot usinga phosphospecific p44/p42 MAP kinase antibody. Caldesmon phosphorylation was assessed using specific phosphocaldesmonantibodies. We report here that treatment of smooth muscle strips withPD-098059, a specific inhibitor of MAP kinase kinase, did notdetectably modify the KCl-evoked contraction but significantlyinhibited the contraction to PE in the absence of extracellularCa2+. In this experimentalcondition, where the contraction occurs in the absence of increases in20-kDa myosin light chain phosphorylation, PD-098059 also inhibitedsignificantly MAP kinase and caldesmon phosphorylation. Collectively,these results demonstrate a direct cause-and-effect relationshipbetween MAP kinase activation and Ca2+-independent smooth musclecontraction and support the concept of caldesmon phosphorylation as themissing link between both events. 相似文献