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991.
Robert V. Farese John L. Orchard Ronald E. Larson Mohammad A. Sabir John S. Davis 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1985,846(2):296-304
Rat pancreatic fragments and acinar preparations were incubated in vitro to characterize further the changes in phosphoinositide metabolism that occur during secretagogue action. Two distinct responses were discernible. The first response, most notably involving a decrease in phosphatidylinositol content, was (a) observed at lower carbachol concentrations in dose-response studies, (b) inhibited by incubation in Ca2+-free media containing 1 mM EGTA, (c) associated with increases in inositol monophosphate production, and (d) provoked by all tissue secretagogues (carbachol, cholecystokinin, secretin, insulin, dibutyryl cAMP and the ionophore A23187), regardless of whether their mechanism of action primarily involved Ca2+ mobilization or cAMP generation. This decrease in phosphatidylinositol content was at least partly due to phospholipase C (and/or D) activation, as evidenced by the increase in inositol monophosphate. The second response, most notably involving markedly increased incorporation of 32PO4 into phosphatidic acid and phosphatidylinositol, was (a) observed at higher carbachol concentrations, (b) not influenced by incubation in Ca2+-free media containing 1 mM EGTA, and (c) associated with increases in inositol triphosphate production. This 32PO4 turnover response was probably largely the result of phospholipase C-mediated hydrolysis of phosphatidylinositol 4′,5′-diphosphate, which, as shown previously, also occurs at higher carbachol concentrations and is insensitive to comparable EGTA-induced Ca2+ deficiency. This phosphatidylinositol 4′,5′-diphosphate hydrolysis response was only observed in the action of agents (carbachol and cholecystokinin) which mobilize Ca2+ via activation of cell surface receptors. The present results indicate that phosphatidylinositol and phosphatidylinositol 4′,5′-diphosphate hydrolysis are truly separable responses to secretagogues acting in the rat pancreas. Furthermore, phosphatidylinositol 4′,5′-diphosphate, rather than phosphatidylinositol hydrolysis is more likely to be associated with receptor activation and Ca2+ mobilization. 相似文献
992.
Diosbulbin d and 8-epidiosbulbin e acetate,norclerodane diterpenoids from dioscorea bulbifera tubers
Robert D.H. Murray Zacarias D. Jorge Nurul H. Khan Mohammad Shahjahan Mohammad Quaisuddin 《Phytochemistry》1984,23(3):623-625
From tubers of Dioscorea buibifera L. var sativa a new 18-norclerodane diterpenoid, 8-epidiosbulbin E acetate, has been isolated, besides the previously known norditerpenoid, diosbulbin D, and its structure established by spectroscopic means. 相似文献
993.
Rhythmic up-down movements were studied in the lateral leaflets ofDesmodium gyrans (L.F.) DC. These were recorded with a video-computer system, whereby the digital video signals from a CCD camera were processed
with special software. Under control conditions (24°C and 0.1 nM cm-2 s-1 of stable, dim light), the average period of lateral leaflet movement was 3.5 min. In the presence of light stimuli (for
2 min), those leaflets always moved toward the light, regardless of where it was applied to any axial part of the pulvinus.
The strongest effect was manifested by a reduced amplitude of movement and, thus, a shortened period, which could be up to
~43% less under moderate light intensity (5 nM cm-2 s-2). Oscillations regained their original regularity over ~10 cycles after the light stimulus was removed. In addition, these
oscillations temporarily disappeared after long exposure (~10 min) under moderate light, or when the leaflets were quickly
exposed to a higher intensity (~12 nM cm-2s-1). Therefore, we have now demonstrated that light can affect physiological parameters that are involved in the control of
oscillations. 相似文献
994.
A simple and rapid flow-injection method is described for the determination of iodide, based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. The calibration graph was linear over the range 1.0-12 x 10(-6) mol/L (r2 = 0.9955) with relative standard deviations (n = 4) in the range 1.0-3.5%. The detection limit (3sigma) was 1.0 x 10(-7) mol/L, with sample throughput of 120/h. The effect of interfering cations [Ca(II), Mg(II), Ni(II), Fe(II), Fe(III) and Pb(II)] and anions (Cl-, SO4(2-), PO4(3-), NO3-, NO2-, F- and SO3(2-)) were studied. The method was applied to iodized salt samples and the results obtained in the range 0.03 +/- 0.005 - 0.10 +/- 0.006 mg I/g were in reasonable agreement with the amount labelled. The method was statistically compared with the results obtained by titration; no significant disagreement at 95% confidence was observed. 相似文献
995.
Christopher J Lelliott Gema Medina-Gomez Natasa Petrovic Adrienn Kis Helena M Feldmann Mikael Bjursell Nadeene Parker Keira Curtis Mark Campbell Ping Hu Dongfang Zhang Sheldon E Litwin Vlad G Zaha Kimberly T Fountain Sihem Boudina Mercedes Jimenez-Linan Margaret Blount Miguel Lopez Aline Meirhaeghe Mohammad Bohlooly-Y Leonard Storlien Maria Strmstedt Michael Snaith Matej Orei
E. Dale Abel Barbara Cannon Antonio Vidal-Puig 《PLoS biology》2006,4(11)
996.
997.
998.
Christian Hansen Nils Hüttebr?uker Wilko Wilkening Mohammad Ashfaq Helmut Ermert 《Biomedizinische Technik》2007,52(4):274-283
In clinical diagnostics, ultrasonographic contrast-agent imaging gives access to medical parameters such as perfusion and vascularization. In addition to the artifacts that are typical for ultrasonic imaging, e.g., speckle noise and depth-dependent sensitivity and resolution, contrast-agent imaging shows more pronounced depth dependence and may suffer from shadowing artifacts that arise from high attenuation of the ultrasound waves by the contrast agent at high concentrations. By imaging an object from different viewing angles in one 2D image plane and summing the images obtained (spatial compounding), image quality can be increased and artifacts can be suppressed. In the present study, we combined both techniques to overcome the limitations of contrast-agent imaging. We used a commercially available ultrasound scanner and a custom-made high-precision mechanical system to rotate the ultrasound transducer fully around the object under investigation. Using this set-up, ultrasound data were acquired in reflection mode to generate a 360 degrees compound scan of a flow-mimicking phantom supplied with contrast agent. 相似文献
999.
The Major Component of IκBα Proteolysis Occurs Independently of the Proteasome Pathway in Respiratory Syncytial Virus-Infected Pulmonary Epithelial Cells 下载免费PDF全文
1000.
Sahar Khajeh Vahid Razban Tahereh Talaei-Khozani Masoud Soleimani Reza Asadi-Golshan Farzaneh Dehghani Amin Ramezani Zohreh Mostafavi-Pour 《Biologia》2018,73(7):715-726
High incidence of articular cartilage defects resulting from age-related degeneration or trauma injuries is a major problem worldwide. Limited self-regeneration ability of cartilage often leads to inappropriate biochemistry and structure of healed tissue. Considering Impairments of traditional treatments, cell-based therapies are promising. The rapid ex vivo expansion and chondrogenic differentiation capability make dental pulp stem cells (DPSCs) a favorable cell type for therapeutic application, however strategies in order to efficient cartilage tissue-like production are imperative. In the present study the potential role of hypoxia mimicking agent, cobalt chloride (CoCl2), on chondrogenic differentiation of human DPSCs was surveyed. Cell viability assay used to obtain the optimum dose and exposure time of CoCl2. DPSCs were differentiated in pellet culture system after CoCl2 pretreatment. Chondrogenic differentiation efficiency was evaluated by histological and immunohistological analyses. The results showed that CoCl2 led to increased pellet size, integrity and matrix deposition with organizations more resembled typical cartilage lacuna structure. Furthermore, CoCl2 could improve differentiation by elevated chondrogenic markers, glycosaminoglycans (GAGs) and collagen II expression. CoCl2 pretreatment mitigated hypertrophy, as well, which was reflected in decreased collagen X expression. Alkaline phosphatase (ALP) specific activity did not change significantly by CoCl2 preconditioning. Based on current study hypoxia mimicking agent, CoCl2, could be suggested to promote DPSCs chondrogenic differentiation. 相似文献